2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
4 * Copyright (c) 2004 Poul-Henning Kamp
5 * Copyright (c) 1994,1997 John S. Dyson
6 * Copyright (c) 2013 The FreeBSD Foundation
9 * Portions of this software were developed by Konstantin Belousov
10 * under sponsorship from the FreeBSD Foundation.
12 * Redistribution and use in source and binary forms, with or without
13 * modification, are permitted provided that the following conditions
15 * 1. Redistributions of source code must retain the above copyright
16 * notice, this list of conditions and the following disclaimer.
17 * 2. Redistributions in binary form must reproduce the above copyright
18 * notice, this list of conditions and the following disclaimer in the
19 * documentation and/or other materials provided with the distribution.
21 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
35 * this file contains a new buffer I/O scheme implementing a coherent
36 * VM object and buffer cache scheme. Pains have been taken to make
37 * sure that the performance degradation associated with schemes such
38 * as this is not realized.
40 * Author: John S. Dyson
41 * Significant help during the development and debugging phases
42 * had been provided by David Greenman, also of the FreeBSD core team.
44 * see man buf(9) for more info.
47 #include <sys/cdefs.h>
48 __FBSDID("$FreeBSD$");
50 #include <sys/param.h>
51 #include <sys/systm.h>
54 #include <sys/bitset.h>
56 #include <sys/counter.h>
58 #include <sys/devicestat.h>
59 #include <sys/eventhandler.h>
62 #include <sys/limits.h>
64 #include <sys/malloc.h>
65 #include <sys/mount.h>
66 #include <sys/mutex.h>
67 #include <sys/kernel.h>
68 #include <sys/kthread.h>
70 #include <sys/racct.h>
71 #include <sys/refcount.h>
72 #include <sys/resourcevar.h>
73 #include <sys/rwlock.h>
75 #include <sys/sysctl.h>
76 #include <sys/syscallsubr.h>
78 #include <sys/vmmeter.h>
79 #include <sys/vnode.h>
80 #include <sys/watchdog.h>
81 #include <geom/geom.h>
83 #include <vm/vm_param.h>
84 #include <vm/vm_kern.h>
85 #include <vm/vm_object.h>
86 #include <vm/vm_page.h>
87 #include <vm/vm_pageout.h>
88 #include <vm/vm_pager.h>
89 #include <vm/vm_extern.h>
90 #include <vm/vm_map.h>
91 #include <vm/swap_pager.h>
93 static MALLOC_DEFINE(M_BIOBUF, "biobuf", "BIO buffer");
95 struct bio_ops bioops; /* I/O operation notification */
97 struct buf_ops buf_ops_bio = {
98 .bop_name = "buf_ops_bio",
99 .bop_write = bufwrite,
100 .bop_strategy = bufstrategy,
102 .bop_bdflush = bufbdflush,
106 struct mtx_padalign bq_lock;
107 TAILQ_HEAD(, buf) bq_queue;
109 uint16_t bq_subqueue;
111 } __aligned(CACHE_LINE_SIZE);
113 #define BQ_LOCKPTR(bq) (&(bq)->bq_lock)
114 #define BQ_LOCK(bq) mtx_lock(BQ_LOCKPTR((bq)))
115 #define BQ_UNLOCK(bq) mtx_unlock(BQ_LOCKPTR((bq)))
116 #define BQ_ASSERT_LOCKED(bq) mtx_assert(BQ_LOCKPTR((bq)), MA_OWNED)
119 struct bufqueue bd_subq[MAXCPU + 1]; /* Per-cpu sub queues + global */
120 struct bufqueue bd_dirtyq;
121 struct bufqueue *bd_cleanq;
122 struct mtx_padalign bd_run_lock;
127 long bd_bufspacethresh;
128 int bd_hifreebuffers;
129 int bd_lofreebuffers;
130 int bd_hidirtybuffers;
131 int bd_lodirtybuffers;
132 int bd_dirtybufthresh;
136 int __aligned(CACHE_LINE_SIZE) bd_numdirtybuffers;
137 int __aligned(CACHE_LINE_SIZE) bd_running;
138 long __aligned(CACHE_LINE_SIZE) bd_bufspace;
139 int __aligned(CACHE_LINE_SIZE) bd_freebuffers;
140 } __aligned(CACHE_LINE_SIZE);
142 #define BD_LOCKPTR(bd) (&(bd)->bd_cleanq->bq_lock)
143 #define BD_LOCK(bd) mtx_lock(BD_LOCKPTR((bd)))
144 #define BD_UNLOCK(bd) mtx_unlock(BD_LOCKPTR((bd)))
145 #define BD_ASSERT_LOCKED(bd) mtx_assert(BD_LOCKPTR((bd)), MA_OWNED)
146 #define BD_RUN_LOCKPTR(bd) (&(bd)->bd_run_lock)
147 #define BD_RUN_LOCK(bd) mtx_lock(BD_RUN_LOCKPTR((bd)))
148 #define BD_RUN_UNLOCK(bd) mtx_unlock(BD_RUN_LOCKPTR((bd)))
149 #define BD_DOMAIN(bd) (bd - bdomain)
151 static char *buf; /* buffer header pool */
155 return ((struct buf *)(buf + (sizeof(struct buf) +
156 sizeof(vm_page_t) * atop(maxbcachebuf)) * i));
159 caddr_t __read_mostly unmapped_buf;
161 /* Used below and for softdep flushing threads in ufs/ffs/ffs_softdep.c */
162 struct proc *bufdaemonproc;
164 static void vm_hold_free_pages(struct buf *bp, int newbsize);
165 static void vm_hold_load_pages(struct buf *bp, vm_offset_t from,
167 static void vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, vm_page_t m);
168 static void vfs_page_set_validclean(struct buf *bp, vm_ooffset_t off,
170 static void vfs_clean_pages_dirty_buf(struct buf *bp);
171 static void vfs_setdirty_range(struct buf *bp);
172 static void vfs_vmio_invalidate(struct buf *bp);
173 static void vfs_vmio_truncate(struct buf *bp, int npages);
174 static void vfs_vmio_extend(struct buf *bp, int npages, int size);
175 static int vfs_bio_clcheck(struct vnode *vp, int size,
176 daddr_t lblkno, daddr_t blkno);
177 static void breada(struct vnode *, daddr_t *, int *, int, struct ucred *, int,
178 void (*)(struct buf *));
179 static int buf_flush(struct vnode *vp, struct bufdomain *, int);
180 static int flushbufqueues(struct vnode *, struct bufdomain *, int, int);
181 static void buf_daemon(void);
182 static __inline void bd_wakeup(void);
183 static int sysctl_runningspace(SYSCTL_HANDLER_ARGS);
184 static void bufkva_reclaim(vmem_t *, int);
185 static void bufkva_free(struct buf *);
186 static int buf_import(void *, void **, int, int, int);
187 static void buf_release(void *, void **, int);
188 static void maxbcachebuf_adjust(void);
189 static inline struct bufdomain *bufdomain(struct buf *);
190 static void bq_remove(struct bufqueue *bq, struct buf *bp);
191 static void bq_insert(struct bufqueue *bq, struct buf *bp, bool unlock);
192 static int buf_recycle(struct bufdomain *, bool kva);
193 static void bq_init(struct bufqueue *bq, int qindex, int cpu,
194 const char *lockname);
195 static void bd_init(struct bufdomain *bd);
196 static int bd_flushall(struct bufdomain *bd);
197 static int sysctl_bufdomain_long(SYSCTL_HANDLER_ARGS);
198 static int sysctl_bufdomain_int(SYSCTL_HANDLER_ARGS);
200 static int sysctl_bufspace(SYSCTL_HANDLER_ARGS);
201 int vmiodirenable = TRUE;
202 SYSCTL_INT(_vfs, OID_AUTO, vmiodirenable, CTLFLAG_RW, &vmiodirenable, 0,
203 "Use the VM system for directory writes");
204 long runningbufspace;
205 SYSCTL_LONG(_vfs, OID_AUTO, runningbufspace, CTLFLAG_RD, &runningbufspace, 0,
206 "Amount of presently outstanding async buffer io");
207 SYSCTL_PROC(_vfs, OID_AUTO, bufspace, CTLTYPE_LONG|CTLFLAG_MPSAFE|CTLFLAG_RD,
208 NULL, 0, sysctl_bufspace, "L", "Physical memory used for buffers");
209 static counter_u64_t bufkvaspace;
210 SYSCTL_COUNTER_U64(_vfs, OID_AUTO, bufkvaspace, CTLFLAG_RD, &bufkvaspace,
211 "Kernel virtual memory used for buffers");
212 static long maxbufspace;
213 SYSCTL_PROC(_vfs, OID_AUTO, maxbufspace,
214 CTLTYPE_LONG|CTLFLAG_MPSAFE|CTLFLAG_RW, &maxbufspace,
215 __offsetof(struct bufdomain, bd_maxbufspace), sysctl_bufdomain_long, "L",
216 "Maximum allowed value of bufspace (including metadata)");
217 static long bufmallocspace;
218 SYSCTL_LONG(_vfs, OID_AUTO, bufmallocspace, CTLFLAG_RD, &bufmallocspace, 0,
219 "Amount of malloced memory for buffers");
220 static long maxbufmallocspace;
221 SYSCTL_LONG(_vfs, OID_AUTO, maxmallocbufspace, CTLFLAG_RW, &maxbufmallocspace,
222 0, "Maximum amount of malloced memory for buffers");
223 static long lobufspace;
224 SYSCTL_PROC(_vfs, OID_AUTO, lobufspace,
225 CTLTYPE_LONG|CTLFLAG_MPSAFE|CTLFLAG_RW, &lobufspace,
226 __offsetof(struct bufdomain, bd_lobufspace), sysctl_bufdomain_long, "L",
227 "Minimum amount of buffers we want to have");
229 SYSCTL_PROC(_vfs, OID_AUTO, hibufspace,
230 CTLTYPE_LONG|CTLFLAG_MPSAFE|CTLFLAG_RW, &hibufspace,
231 __offsetof(struct bufdomain, bd_hibufspace), sysctl_bufdomain_long, "L",
232 "Maximum allowed value of bufspace (excluding metadata)");
234 SYSCTL_PROC(_vfs, OID_AUTO, bufspacethresh,
235 CTLTYPE_LONG|CTLFLAG_MPSAFE|CTLFLAG_RW, &bufspacethresh,
236 __offsetof(struct bufdomain, bd_bufspacethresh), sysctl_bufdomain_long, "L",
237 "Bufspace consumed before waking the daemon to free some");
238 static counter_u64_t buffreekvacnt;
239 SYSCTL_COUNTER_U64(_vfs, OID_AUTO, buffreekvacnt, CTLFLAG_RW, &buffreekvacnt,
240 "Number of times we have freed the KVA space from some buffer");
241 static counter_u64_t bufdefragcnt;
242 SYSCTL_COUNTER_U64(_vfs, OID_AUTO, bufdefragcnt, CTLFLAG_RW, &bufdefragcnt,
243 "Number of times we have had to repeat buffer allocation to defragment");
244 static long lorunningspace;
245 SYSCTL_PROC(_vfs, OID_AUTO, lorunningspace, CTLTYPE_LONG | CTLFLAG_MPSAFE |
246 CTLFLAG_RW, &lorunningspace, 0, sysctl_runningspace, "L",
247 "Minimum preferred space used for in-progress I/O");
248 static long hirunningspace;
249 SYSCTL_PROC(_vfs, OID_AUTO, hirunningspace, CTLTYPE_LONG | CTLFLAG_MPSAFE |
250 CTLFLAG_RW, &hirunningspace, 0, sysctl_runningspace, "L",
251 "Maximum amount of space to use for in-progress I/O");
252 int dirtybufferflushes;
253 SYSCTL_INT(_vfs, OID_AUTO, dirtybufferflushes, CTLFLAG_RW, &dirtybufferflushes,
254 0, "Number of bdwrite to bawrite conversions to limit dirty buffers");
256 SYSCTL_INT(_vfs, OID_AUTO, bdwriteskip, CTLFLAG_RW, &bdwriteskip,
257 0, "Number of buffers supplied to bdwrite with snapshot deadlock risk");
258 int altbufferflushes;
259 SYSCTL_INT(_vfs, OID_AUTO, altbufferflushes, CTLFLAG_RW | CTLFLAG_STATS,
260 &altbufferflushes, 0, "Number of fsync flushes to limit dirty buffers");
261 static int recursiveflushes;
262 SYSCTL_INT(_vfs, OID_AUTO, recursiveflushes, CTLFLAG_RW | CTLFLAG_STATS,
263 &recursiveflushes, 0, "Number of flushes skipped due to being recursive");
264 static int sysctl_numdirtybuffers(SYSCTL_HANDLER_ARGS);
265 SYSCTL_PROC(_vfs, OID_AUTO, numdirtybuffers,
266 CTLTYPE_INT|CTLFLAG_MPSAFE|CTLFLAG_RD, NULL, 0, sysctl_numdirtybuffers, "I",
267 "Number of buffers that are dirty (has unwritten changes) at the moment");
268 static int lodirtybuffers;
269 SYSCTL_PROC(_vfs, OID_AUTO, lodirtybuffers,
270 CTLTYPE_INT|CTLFLAG_MPSAFE|CTLFLAG_RW, &lodirtybuffers,
271 __offsetof(struct bufdomain, bd_lodirtybuffers), sysctl_bufdomain_int, "I",
272 "How many buffers we want to have free before bufdaemon can sleep");
273 static int hidirtybuffers;
274 SYSCTL_PROC(_vfs, OID_AUTO, hidirtybuffers,
275 CTLTYPE_INT|CTLFLAG_MPSAFE|CTLFLAG_RW, &hidirtybuffers,
276 __offsetof(struct bufdomain, bd_hidirtybuffers), sysctl_bufdomain_int, "I",
277 "When the number of dirty buffers is considered severe");
279 SYSCTL_PROC(_vfs, OID_AUTO, dirtybufthresh,
280 CTLTYPE_INT|CTLFLAG_MPSAFE|CTLFLAG_RW, &dirtybufthresh,
281 __offsetof(struct bufdomain, bd_dirtybufthresh), sysctl_bufdomain_int, "I",
282 "Number of bdwrite to bawrite conversions to clear dirty buffers");
283 static int numfreebuffers;
284 SYSCTL_INT(_vfs, OID_AUTO, numfreebuffers, CTLFLAG_RD, &numfreebuffers, 0,
285 "Number of free buffers");
286 static int lofreebuffers;
287 SYSCTL_PROC(_vfs, OID_AUTO, lofreebuffers,
288 CTLTYPE_INT|CTLFLAG_MPSAFE|CTLFLAG_RW, &lofreebuffers,
289 __offsetof(struct bufdomain, bd_lofreebuffers), sysctl_bufdomain_int, "I",
290 "Target number of free buffers");
291 static int hifreebuffers;
292 SYSCTL_PROC(_vfs, OID_AUTO, hifreebuffers,
293 CTLTYPE_INT|CTLFLAG_MPSAFE|CTLFLAG_RW, &hifreebuffers,
294 __offsetof(struct bufdomain, bd_hifreebuffers), sysctl_bufdomain_int, "I",
295 "Threshold for clean buffer recycling");
296 static counter_u64_t getnewbufcalls;
297 SYSCTL_COUNTER_U64(_vfs, OID_AUTO, getnewbufcalls, CTLFLAG_RD,
298 &getnewbufcalls, "Number of calls to getnewbuf");
299 static counter_u64_t getnewbufrestarts;
300 SYSCTL_COUNTER_U64(_vfs, OID_AUTO, getnewbufrestarts, CTLFLAG_RD,
302 "Number of times getnewbuf has had to restart a buffer acquisition");
303 static counter_u64_t mappingrestarts;
304 SYSCTL_COUNTER_U64(_vfs, OID_AUTO, mappingrestarts, CTLFLAG_RD,
306 "Number of times getblk has had to restart a buffer mapping for "
308 static counter_u64_t numbufallocfails;
309 SYSCTL_COUNTER_U64(_vfs, OID_AUTO, numbufallocfails, CTLFLAG_RW,
310 &numbufallocfails, "Number of times buffer allocations failed");
311 static int flushbufqtarget = 100;
312 SYSCTL_INT(_vfs, OID_AUTO, flushbufqtarget, CTLFLAG_RW, &flushbufqtarget, 0,
313 "Amount of work to do in flushbufqueues when helping bufdaemon");
314 static counter_u64_t notbufdflushes;
315 SYSCTL_COUNTER_U64(_vfs, OID_AUTO, notbufdflushes, CTLFLAG_RD, ¬bufdflushes,
316 "Number of dirty buffer flushes done by the bufdaemon helpers");
317 static long barrierwrites;
318 SYSCTL_LONG(_vfs, OID_AUTO, barrierwrites, CTLFLAG_RW | CTLFLAG_STATS,
319 &barrierwrites, 0, "Number of barrier writes");
320 SYSCTL_INT(_vfs, OID_AUTO, unmapped_buf_allowed, CTLFLAG_RD,
321 &unmapped_buf_allowed, 0,
322 "Permit the use of the unmapped i/o");
323 int maxbcachebuf = MAXBCACHEBUF;
324 SYSCTL_INT(_vfs, OID_AUTO, maxbcachebuf, CTLFLAG_RDTUN, &maxbcachebuf, 0,
325 "Maximum size of a buffer cache block");
328 * This lock synchronizes access to bd_request.
330 static struct mtx_padalign __exclusive_cache_line bdlock;
333 * This lock protects the runningbufreq and synchronizes runningbufwakeup and
334 * waitrunningbufspace().
336 static struct mtx_padalign __exclusive_cache_line rbreqlock;
339 * Lock that protects bdirtywait.
341 static struct mtx_padalign __exclusive_cache_line bdirtylock;
344 * Wakeup point for bufdaemon, as well as indicator of whether it is already
345 * active. Set to 1 when the bufdaemon is already "on" the queue, 0 when it
348 static int bd_request;
351 * Request for the buf daemon to write more buffers than is indicated by
352 * lodirtybuf. This may be necessary to push out excess dependencies or
353 * defragment the address space where a simple count of the number of dirty
354 * buffers is insufficient to characterize the demand for flushing them.
356 static int bd_speedupreq;
359 * Synchronization (sleep/wakeup) variable for active buffer space requests.
360 * Set when wait starts, cleared prior to wakeup().
361 * Used in runningbufwakeup() and waitrunningbufspace().
363 static int runningbufreq;
366 * Synchronization for bwillwrite() waiters.
368 static int bdirtywait;
371 * Definitions for the buffer free lists.
373 #define QUEUE_NONE 0 /* on no queue */
374 #define QUEUE_EMPTY 1 /* empty buffer headers */
375 #define QUEUE_DIRTY 2 /* B_DELWRI buffers */
376 #define QUEUE_CLEAN 3 /* non-B_DELWRI buffers */
377 #define QUEUE_SENTINEL 4 /* not an queue index, but mark for sentinel */
379 /* Maximum number of buffer domains. */
380 #define BUF_DOMAINS 8
382 struct bufdomainset bdlodirty; /* Domains > lodirty */
383 struct bufdomainset bdhidirty; /* Domains > hidirty */
385 /* Configured number of clean queues. */
386 static int __read_mostly buf_domains;
388 BITSET_DEFINE(bufdomainset, BUF_DOMAINS);
389 struct bufdomain __exclusive_cache_line bdomain[BUF_DOMAINS];
390 struct bufqueue __exclusive_cache_line bqempty;
393 * per-cpu empty buffer cache.
398 * Single global constant for BUF_WMESG, to avoid getting multiple references.
399 * buf_wmesg is referred from macros.
401 const char *buf_wmesg = BUF_WMESG;
404 sysctl_runningspace(SYSCTL_HANDLER_ARGS)
409 value = *(long *)arg1;
410 error = sysctl_handle_long(oidp, &value, 0, req);
411 if (error != 0 || req->newptr == NULL)
413 mtx_lock(&rbreqlock);
414 if (arg1 == &hirunningspace) {
415 if (value < lorunningspace)
418 hirunningspace = value;
420 KASSERT(arg1 == &lorunningspace,
421 ("%s: unknown arg1", __func__));
422 if (value > hirunningspace)
425 lorunningspace = value;
427 mtx_unlock(&rbreqlock);
432 sysctl_bufdomain_int(SYSCTL_HANDLER_ARGS)
438 value = *(int *)arg1;
439 error = sysctl_handle_int(oidp, &value, 0, req);
440 if (error != 0 || req->newptr == NULL)
442 *(int *)arg1 = value;
443 for (i = 0; i < buf_domains; i++)
444 *(int *)(uintptr_t)(((uintptr_t)&bdomain[i]) + arg2) =
451 sysctl_bufdomain_long(SYSCTL_HANDLER_ARGS)
457 value = *(long *)arg1;
458 error = sysctl_handle_long(oidp, &value, 0, req);
459 if (error != 0 || req->newptr == NULL)
461 *(long *)arg1 = value;
462 for (i = 0; i < buf_domains; i++)
463 *(long *)(uintptr_t)(((uintptr_t)&bdomain[i]) + arg2) =
469 #if defined(COMPAT_FREEBSD4) || defined(COMPAT_FREEBSD5) || \
470 defined(COMPAT_FREEBSD6) || defined(COMPAT_FREEBSD7)
472 sysctl_bufspace(SYSCTL_HANDLER_ARGS)
479 for (i = 0; i < buf_domains; i++)
480 lvalue += bdomain[i].bd_bufspace;
481 if (sizeof(int) == sizeof(long) || req->oldlen >= sizeof(long))
482 return (sysctl_handle_long(oidp, &lvalue, 0, req));
483 if (lvalue > INT_MAX)
484 /* On overflow, still write out a long to trigger ENOMEM. */
485 return (sysctl_handle_long(oidp, &lvalue, 0, req));
487 return (sysctl_handle_int(oidp, &ivalue, 0, req));
491 sysctl_bufspace(SYSCTL_HANDLER_ARGS)
497 for (i = 0; i < buf_domains; i++)
498 lvalue += bdomain[i].bd_bufspace;
499 return (sysctl_handle_long(oidp, &lvalue, 0, req));
504 sysctl_numdirtybuffers(SYSCTL_HANDLER_ARGS)
510 for (i = 0; i < buf_domains; i++)
511 value += bdomain[i].bd_numdirtybuffers;
512 return (sysctl_handle_int(oidp, &value, 0, req));
518 * Wakeup any bwillwrite() waiters.
523 mtx_lock(&bdirtylock);
528 mtx_unlock(&bdirtylock);
534 * Clear a domain from the appropriate bitsets when dirtybuffers
538 bd_clear(struct bufdomain *bd)
541 mtx_lock(&bdirtylock);
542 if (bd->bd_numdirtybuffers <= bd->bd_lodirtybuffers)
543 BIT_CLR(BUF_DOMAINS, BD_DOMAIN(bd), &bdlodirty);
544 if (bd->bd_numdirtybuffers <= bd->bd_hidirtybuffers)
545 BIT_CLR(BUF_DOMAINS, BD_DOMAIN(bd), &bdhidirty);
546 mtx_unlock(&bdirtylock);
552 * Set a domain in the appropriate bitsets when dirtybuffers
556 bd_set(struct bufdomain *bd)
559 mtx_lock(&bdirtylock);
560 if (bd->bd_numdirtybuffers > bd->bd_lodirtybuffers)
561 BIT_SET(BUF_DOMAINS, BD_DOMAIN(bd), &bdlodirty);
562 if (bd->bd_numdirtybuffers > bd->bd_hidirtybuffers)
563 BIT_SET(BUF_DOMAINS, BD_DOMAIN(bd), &bdhidirty);
564 mtx_unlock(&bdirtylock);
570 * Decrement the numdirtybuffers count by one and wakeup any
571 * threads blocked in bwillwrite().
574 bdirtysub(struct buf *bp)
576 struct bufdomain *bd;
580 num = atomic_fetchadd_int(&bd->bd_numdirtybuffers, -1);
581 if (num == (bd->bd_lodirtybuffers + bd->bd_hidirtybuffers) / 2)
583 if (num == bd->bd_lodirtybuffers || num == bd->bd_hidirtybuffers)
590 * Increment the numdirtybuffers count by one and wakeup the buf
594 bdirtyadd(struct buf *bp)
596 struct bufdomain *bd;
600 * Only do the wakeup once as we cross the boundary. The
601 * buf daemon will keep running until the condition clears.
604 num = atomic_fetchadd_int(&bd->bd_numdirtybuffers, 1);
605 if (num == (bd->bd_lodirtybuffers + bd->bd_hidirtybuffers) / 2)
607 if (num == bd->bd_lodirtybuffers || num == bd->bd_hidirtybuffers)
612 * bufspace_daemon_wakeup:
614 * Wakeup the daemons responsible for freeing clean bufs.
617 bufspace_daemon_wakeup(struct bufdomain *bd)
621 * avoid the lock if the daemon is running.
623 if (atomic_fetchadd_int(&bd->bd_running, 1) == 0) {
625 atomic_store_int(&bd->bd_running, 1);
626 wakeup(&bd->bd_running);
632 * bufspace_daemon_wait:
634 * Sleep until the domain falls below a limit or one second passes.
637 bufspace_daemon_wait(struct bufdomain *bd)
640 * Re-check our limits and sleep. bd_running must be
641 * cleared prior to checking the limits to avoid missed
642 * wakeups. The waker will adjust one of bufspace or
643 * freebuffers prior to checking bd_running.
646 atomic_store_int(&bd->bd_running, 0);
647 if (bd->bd_bufspace < bd->bd_bufspacethresh &&
648 bd->bd_freebuffers > bd->bd_lofreebuffers) {
649 msleep(&bd->bd_running, BD_RUN_LOCKPTR(bd), PRIBIO|PDROP,
652 /* Avoid spurious wakeups while running. */
653 atomic_store_int(&bd->bd_running, 1);
661 * Adjust the reported bufspace for a KVA managed buffer, possibly
662 * waking any waiters.
665 bufspace_adjust(struct buf *bp, int bufsize)
667 struct bufdomain *bd;
671 KASSERT((bp->b_flags & B_MALLOC) == 0,
672 ("bufspace_adjust: malloc buf %p", bp));
674 diff = bufsize - bp->b_bufsize;
676 atomic_subtract_long(&bd->bd_bufspace, -diff);
677 } else if (diff > 0) {
678 space = atomic_fetchadd_long(&bd->bd_bufspace, diff);
679 /* Wake up the daemon on the transition. */
680 if (space < bd->bd_bufspacethresh &&
681 space + diff >= bd->bd_bufspacethresh)
682 bufspace_daemon_wakeup(bd);
684 bp->b_bufsize = bufsize;
690 * Reserve bufspace before calling allocbuf(). metadata has a
691 * different space limit than data.
694 bufspace_reserve(struct bufdomain *bd, int size, bool metadata)
700 limit = bd->bd_maxbufspace;
702 limit = bd->bd_hibufspace;
703 space = atomic_fetchadd_long(&bd->bd_bufspace, size);
706 atomic_subtract_long(&bd->bd_bufspace, size);
710 /* Wake up the daemon on the transition. */
711 if (space < bd->bd_bufspacethresh && new >= bd->bd_bufspacethresh)
712 bufspace_daemon_wakeup(bd);
720 * Release reserved bufspace after bufspace_adjust() has consumed it.
723 bufspace_release(struct bufdomain *bd, int size)
726 atomic_subtract_long(&bd->bd_bufspace, size);
732 * Wait for bufspace, acting as the buf daemon if a locked vnode is
733 * supplied. bd_wanted must be set prior to polling for space. The
734 * operation must be re-tried on return.
737 bufspace_wait(struct bufdomain *bd, struct vnode *vp, int gbflags,
738 int slpflag, int slptimeo)
741 int error, fl, norunbuf;
743 if ((gbflags & GB_NOWAIT_BD) != 0)
748 while (bd->bd_wanted) {
749 if (vp != NULL && vp->v_type != VCHR &&
750 (td->td_pflags & TDP_BUFNEED) == 0) {
753 * getblk() is called with a vnode locked, and
754 * some majority of the dirty buffers may as
755 * well belong to the vnode. Flushing the
756 * buffers there would make a progress that
757 * cannot be achieved by the buf_daemon, that
758 * cannot lock the vnode.
760 norunbuf = ~(TDP_BUFNEED | TDP_NORUNNINGBUF) |
761 (td->td_pflags & TDP_NORUNNINGBUF);
764 * Play bufdaemon. The getnewbuf() function
765 * may be called while the thread owns lock
766 * for another dirty buffer for the same
767 * vnode, which makes it impossible to use
768 * VOP_FSYNC() there, due to the buffer lock
771 td->td_pflags |= TDP_BUFNEED | TDP_NORUNNINGBUF;
772 fl = buf_flush(vp, bd, flushbufqtarget);
773 td->td_pflags &= norunbuf;
777 if (bd->bd_wanted == 0)
780 error = msleep(&bd->bd_wanted, BD_LOCKPTR(bd),
781 (PRIBIO + 4) | slpflag, "newbuf", slptimeo);
791 * buffer space management daemon. Tries to maintain some marginal
792 * amount of free buffer space so that requesting processes neither
793 * block nor work to reclaim buffers.
796 bufspace_daemon(void *arg)
798 struct bufdomain *bd;
800 EVENTHANDLER_REGISTER(shutdown_pre_sync, kthread_shutdown, curthread,
801 SHUTDOWN_PRI_LAST + 100);
805 kthread_suspend_check();
808 * Free buffers from the clean queue until we meet our
811 * Theory of operation: The buffer cache is most efficient
812 * when some free buffer headers and space are always
813 * available to getnewbuf(). This daemon attempts to prevent
814 * the excessive blocking and synchronization associated
815 * with shortfall. It goes through three phases according
818 * 1) The daemon wakes up voluntarily once per-second
819 * during idle periods when the counters are below
820 * the wakeup thresholds (bufspacethresh, lofreebuffers).
822 * 2) The daemon wakes up as we cross the thresholds
823 * ahead of any potential blocking. This may bounce
824 * slightly according to the rate of consumption and
827 * 3) The daemon and consumers are starved for working
828 * clean buffers. This is the 'bufspace' sleep below
829 * which will inefficiently trade bufs with bqrelse
830 * until we return to condition 2.
832 while (bd->bd_bufspace > bd->bd_lobufspace ||
833 bd->bd_freebuffers < bd->bd_hifreebuffers) {
834 if (buf_recycle(bd, false) != 0) {
838 * Speedup dirty if we've run out of clean
839 * buffers. This is possible in particular
840 * because softdep may held many bufs locked
841 * pending writes to other bufs which are
842 * marked for delayed write, exhausting
843 * clean space until they are written.
848 msleep(&bd->bd_wanted, BD_LOCKPTR(bd),
849 PRIBIO|PDROP, "bufspace", hz/10);
855 bufspace_daemon_wait(bd);
862 * Adjust the reported bufspace for a malloc managed buffer, possibly
863 * waking any waiters.
866 bufmallocadjust(struct buf *bp, int bufsize)
870 KASSERT((bp->b_flags & B_MALLOC) != 0,
871 ("bufmallocadjust: non-malloc buf %p", bp));
872 diff = bufsize - bp->b_bufsize;
874 atomic_subtract_long(&bufmallocspace, -diff);
876 atomic_add_long(&bufmallocspace, diff);
877 bp->b_bufsize = bufsize;
883 * Wake up processes that are waiting on asynchronous writes to fall
884 * below lorunningspace.
890 mtx_lock(&rbreqlock);
893 wakeup(&runningbufreq);
895 mtx_unlock(&rbreqlock);
901 * Decrement the outstanding write count according.
904 runningbufwakeup(struct buf *bp)
908 bspace = bp->b_runningbufspace;
911 space = atomic_fetchadd_long(&runningbufspace, -bspace);
912 KASSERT(space >= bspace, ("runningbufspace underflow %ld %ld",
914 bp->b_runningbufspace = 0;
916 * Only acquire the lock and wakeup on the transition from exceeding
917 * the threshold to falling below it.
919 if (space < lorunningspace)
921 if (space - bspace > lorunningspace)
927 * waitrunningbufspace()
929 * runningbufspace is a measure of the amount of I/O currently
930 * running. This routine is used in async-write situations to
931 * prevent creating huge backups of pending writes to a device.
932 * Only asynchronous writes are governed by this function.
934 * This does NOT turn an async write into a sync write. It waits
935 * for earlier writes to complete and generally returns before the
936 * caller's write has reached the device.
939 waitrunningbufspace(void)
942 mtx_lock(&rbreqlock);
943 while (runningbufspace > hirunningspace) {
945 msleep(&runningbufreq, &rbreqlock, PVM, "wdrain", 0);
947 mtx_unlock(&rbreqlock);
951 * vfs_buf_test_cache:
953 * Called when a buffer is extended. This function clears the B_CACHE
954 * bit if the newly extended portion of the buffer does not contain
958 vfs_buf_test_cache(struct buf *bp, vm_ooffset_t foff, vm_offset_t off,
959 vm_offset_t size, vm_page_t m)
963 * This function and its results are protected by higher level
964 * synchronization requiring vnode and buf locks to page in and
967 if (bp->b_flags & B_CACHE) {
968 int base = (foff + off) & PAGE_MASK;
969 if (vm_page_is_valid(m, base, size) == 0)
970 bp->b_flags &= ~B_CACHE;
974 /* Wake up the buffer daemon if necessary */
980 if (bd_request == 0) {
988 * Adjust the maxbcachbuf tunable.
991 maxbcachebuf_adjust(void)
996 * maxbcachebuf must be a power of 2 >= MAXBSIZE.
999 while (i * 2 <= maxbcachebuf)
1002 if (maxbcachebuf < MAXBSIZE)
1003 maxbcachebuf = MAXBSIZE;
1004 if (maxbcachebuf > maxphys)
1005 maxbcachebuf = maxphys;
1006 if (bootverbose != 0 && maxbcachebuf != MAXBCACHEBUF)
1007 printf("maxbcachebuf=%d\n", maxbcachebuf);
1011 * bd_speedup - speedup the buffer cache flushing code
1020 if (bd_speedupreq == 0 || bd_request == 0)
1025 wakeup(&bd_request);
1026 mtx_unlock(&bdlock);
1030 #define TRANSIENT_DENOM 5
1032 #define TRANSIENT_DENOM 10
1036 * Calculating buffer cache scaling values and reserve space for buffer
1037 * headers. This is called during low level kernel initialization and
1038 * may be called more then once. We CANNOT write to the memory area
1039 * being reserved at this time.
1042 kern_vfs_bio_buffer_alloc(caddr_t v, long physmem_est)
1045 long maxbuf, maxbuf_sz, buf_sz, biotmap_sz;
1048 * With KASAN or KMSAN enabled, the kernel map is shadowed. Account for
1049 * this when sizing maps based on the amount of physical memory
1053 physmem_est = (physmem_est * KASAN_SHADOW_SCALE) /
1054 (KASAN_SHADOW_SCALE + 1);
1055 #elif defined(KMSAN)
1059 * KMSAN cannot reliably determine whether buffer data is initialized
1060 * unless it is updated through a KVA mapping.
1062 unmapped_buf_allowed = 0;
1066 * physmem_est is in pages. Convert it to kilobytes (assumes
1067 * PAGE_SIZE is >= 1K)
1069 physmem_est = physmem_est * (PAGE_SIZE / 1024);
1071 maxbcachebuf_adjust();
1073 * The nominal buffer size (and minimum KVA allocation) is BKVASIZE.
1074 * For the first 64MB of ram nominally allocate sufficient buffers to
1075 * cover 1/4 of our ram. Beyond the first 64MB allocate additional
1076 * buffers to cover 1/10 of our ram over 64MB. When auto-sizing
1077 * the buffer cache we limit the eventual kva reservation to
1080 * factor represents the 1/4 x ram conversion.
1083 int factor = 4 * BKVASIZE / 1024;
1086 if (physmem_est > 4096)
1087 nbuf += min((physmem_est - 4096) / factor,
1089 if (physmem_est > 65536)
1090 nbuf += min((physmem_est - 65536) * 2 / (factor * 5),
1091 32 * 1024 * 1024 / (factor * 5));
1093 if (maxbcache && nbuf > maxbcache / BKVASIZE)
1094 nbuf = maxbcache / BKVASIZE;
1099 /* XXX Avoid unsigned long overflows later on with maxbufspace. */
1100 maxbuf = (LONG_MAX / 3) / BKVASIZE;
1101 if (nbuf > maxbuf) {
1103 printf("Warning: nbufs lowered from %d to %ld\n", nbuf,
1109 * Ideal allocation size for the transient bio submap is 10%
1110 * of the maximal space buffer map. This roughly corresponds
1111 * to the amount of the buffer mapped for typical UFS load.
1113 * Clip the buffer map to reserve space for the transient
1114 * BIOs, if its extent is bigger than 90% (80% on i386) of the
1115 * maximum buffer map extent on the platform.
1117 * The fall-back to the maxbuf in case of maxbcache unset,
1118 * allows to not trim the buffer KVA for the architectures
1119 * with ample KVA space.
1121 if (bio_transient_maxcnt == 0 && unmapped_buf_allowed) {
1122 maxbuf_sz = maxbcache != 0 ? maxbcache : maxbuf * BKVASIZE;
1123 buf_sz = (long)nbuf * BKVASIZE;
1124 if (buf_sz < maxbuf_sz / TRANSIENT_DENOM *
1125 (TRANSIENT_DENOM - 1)) {
1127 * There is more KVA than memory. Do not
1128 * adjust buffer map size, and assign the rest
1129 * of maxbuf to transient map.
1131 biotmap_sz = maxbuf_sz - buf_sz;
1134 * Buffer map spans all KVA we could afford on
1135 * this platform. Give 10% (20% on i386) of
1136 * the buffer map to the transient bio map.
1138 biotmap_sz = buf_sz / TRANSIENT_DENOM;
1139 buf_sz -= biotmap_sz;
1141 if (biotmap_sz / INT_MAX > maxphys)
1142 bio_transient_maxcnt = INT_MAX;
1144 bio_transient_maxcnt = biotmap_sz / maxphys;
1146 * Artificially limit to 1024 simultaneous in-flight I/Os
1147 * using the transient mapping.
1149 if (bio_transient_maxcnt > 1024)
1150 bio_transient_maxcnt = 1024;
1152 nbuf = buf_sz / BKVASIZE;
1156 nswbuf = min(nbuf / 4, 256);
1157 if (nswbuf < NSWBUF_MIN)
1158 nswbuf = NSWBUF_MIN;
1162 * Reserve space for the buffer cache buffers
1165 v = (caddr_t)buf + (sizeof(struct buf) + sizeof(vm_page_t) *
1166 atop(maxbcachebuf)) * nbuf;
1171 /* Initialize the buffer subsystem. Called before use of any buffers. */
1178 KASSERT(maxbcachebuf >= MAXBSIZE,
1179 ("maxbcachebuf (%d) must be >= MAXBSIZE (%d)\n", maxbcachebuf,
1181 bq_init(&bqempty, QUEUE_EMPTY, -1, "bufq empty lock");
1182 mtx_init(&rbreqlock, "runningbufspace lock", NULL, MTX_DEF);
1183 mtx_init(&bdlock, "buffer daemon lock", NULL, MTX_DEF);
1184 mtx_init(&bdirtylock, "dirty buf lock", NULL, MTX_DEF);
1186 unmapped_buf = (caddr_t)kva_alloc(maxphys);
1188 /* finally, initialize each buffer header and stick on empty q */
1189 for (i = 0; i < nbuf; i++) {
1191 bzero(bp, sizeof(*bp) + sizeof(vm_page_t) * atop(maxbcachebuf));
1192 bp->b_flags = B_INVAL;
1193 bp->b_rcred = NOCRED;
1194 bp->b_wcred = NOCRED;
1195 bp->b_qindex = QUEUE_NONE;
1197 bp->b_subqueue = mp_maxid + 1;
1199 bp->b_data = bp->b_kvabase = unmapped_buf;
1200 LIST_INIT(&bp->b_dep);
1202 bq_insert(&bqempty, bp, false);
1206 * maxbufspace is the absolute maximum amount of buffer space we are
1207 * allowed to reserve in KVM and in real terms. The absolute maximum
1208 * is nominally used by metadata. hibufspace is the nominal maximum
1209 * used by most other requests. The differential is required to
1210 * ensure that metadata deadlocks don't occur.
1212 * maxbufspace is based on BKVASIZE. Allocating buffers larger then
1213 * this may result in KVM fragmentation which is not handled optimally
1214 * by the system. XXX This is less true with vmem. We could use
1217 maxbufspace = (long)nbuf * BKVASIZE;
1218 hibufspace = lmax(3 * maxbufspace / 4, maxbufspace - maxbcachebuf * 10);
1219 lobufspace = (hibufspace / 20) * 19; /* 95% */
1220 bufspacethresh = lobufspace + (hibufspace - lobufspace) / 2;
1223 * Note: The 16 MiB upper limit for hirunningspace was chosen
1224 * arbitrarily and may need further tuning. It corresponds to
1225 * 128 outstanding write IO requests (if IO size is 128 KiB),
1226 * which fits with many RAID controllers' tagged queuing limits.
1227 * The lower 1 MiB limit is the historical upper limit for
1230 hirunningspace = lmax(lmin(roundup(hibufspace / 64, maxbcachebuf),
1231 16 * 1024 * 1024), 1024 * 1024);
1232 lorunningspace = roundup((hirunningspace * 2) / 3, maxbcachebuf);
1235 * Limit the amount of malloc memory since it is wired permanently into
1236 * the kernel space. Even though this is accounted for in the buffer
1237 * allocation, we don't want the malloced region to grow uncontrolled.
1238 * The malloc scheme improves memory utilization significantly on
1239 * average (small) directories.
1241 maxbufmallocspace = hibufspace / 20;
1244 * Reduce the chance of a deadlock occurring by limiting the number
1245 * of delayed-write dirty buffers we allow to stack up.
1247 hidirtybuffers = nbuf / 4 + 20;
1248 dirtybufthresh = hidirtybuffers * 9 / 10;
1250 * To support extreme low-memory systems, make sure hidirtybuffers
1251 * cannot eat up all available buffer space. This occurs when our
1252 * minimum cannot be met. We try to size hidirtybuffers to 3/4 our
1253 * buffer space assuming BKVASIZE'd buffers.
1255 while ((long)hidirtybuffers * BKVASIZE > 3 * hibufspace / 4) {
1256 hidirtybuffers >>= 1;
1258 lodirtybuffers = hidirtybuffers / 2;
1261 * lofreebuffers should be sufficient to avoid stalling waiting on
1262 * buf headers under heavy utilization. The bufs in per-cpu caches
1263 * are counted as free but will be unavailable to threads executing
1266 * hifreebuffers is the free target for the bufspace daemon. This
1267 * should be set appropriately to limit work per-iteration.
1269 lofreebuffers = MIN((nbuf / 25) + (20 * mp_ncpus), 128 * mp_ncpus);
1270 hifreebuffers = (3 * lofreebuffers) / 2;
1271 numfreebuffers = nbuf;
1273 /* Setup the kva and free list allocators. */
1274 vmem_set_reclaim(buffer_arena, bufkva_reclaim);
1275 buf_zone = uma_zcache_create("buf free cache",
1276 sizeof(struct buf) + sizeof(vm_page_t) * atop(maxbcachebuf),
1277 NULL, NULL, NULL, NULL, buf_import, buf_release, NULL, 0);
1280 * Size the clean queue according to the amount of buffer space.
1281 * One queue per-256mb up to the max. More queues gives better
1282 * concurrency but less accurate LRU.
1284 buf_domains = MIN(howmany(maxbufspace, 256*1024*1024), BUF_DOMAINS);
1285 for (i = 0 ; i < buf_domains; i++) {
1286 struct bufdomain *bd;
1290 bd->bd_freebuffers = nbuf / buf_domains;
1291 bd->bd_hifreebuffers = hifreebuffers / buf_domains;
1292 bd->bd_lofreebuffers = lofreebuffers / buf_domains;
1293 bd->bd_bufspace = 0;
1294 bd->bd_maxbufspace = maxbufspace / buf_domains;
1295 bd->bd_hibufspace = hibufspace / buf_domains;
1296 bd->bd_lobufspace = lobufspace / buf_domains;
1297 bd->bd_bufspacethresh = bufspacethresh / buf_domains;
1298 bd->bd_numdirtybuffers = 0;
1299 bd->bd_hidirtybuffers = hidirtybuffers / buf_domains;
1300 bd->bd_lodirtybuffers = lodirtybuffers / buf_domains;
1301 bd->bd_dirtybufthresh = dirtybufthresh / buf_domains;
1302 /* Don't allow more than 2% of bufs in the per-cpu caches. */
1303 bd->bd_lim = nbuf / buf_domains / 50 / mp_ncpus;
1305 getnewbufcalls = counter_u64_alloc(M_WAITOK);
1306 getnewbufrestarts = counter_u64_alloc(M_WAITOK);
1307 mappingrestarts = counter_u64_alloc(M_WAITOK);
1308 numbufallocfails = counter_u64_alloc(M_WAITOK);
1309 notbufdflushes = counter_u64_alloc(M_WAITOK);
1310 buffreekvacnt = counter_u64_alloc(M_WAITOK);
1311 bufdefragcnt = counter_u64_alloc(M_WAITOK);
1312 bufkvaspace = counter_u64_alloc(M_WAITOK);
1317 vfs_buf_check_mapped(struct buf *bp)
1320 KASSERT(bp->b_kvabase != unmapped_buf,
1321 ("mapped buf: b_kvabase was not updated %p", bp));
1322 KASSERT(bp->b_data != unmapped_buf,
1323 ("mapped buf: b_data was not updated %p", bp));
1324 KASSERT(bp->b_data < unmapped_buf || bp->b_data >= unmapped_buf +
1325 maxphys, ("b_data + b_offset unmapped %p", bp));
1329 vfs_buf_check_unmapped(struct buf *bp)
1332 KASSERT(bp->b_data == unmapped_buf,
1333 ("unmapped buf: corrupted b_data %p", bp));
1336 #define BUF_CHECK_MAPPED(bp) vfs_buf_check_mapped(bp)
1337 #define BUF_CHECK_UNMAPPED(bp) vfs_buf_check_unmapped(bp)
1339 #define BUF_CHECK_MAPPED(bp) do {} while (0)
1340 #define BUF_CHECK_UNMAPPED(bp) do {} while (0)
1344 isbufbusy(struct buf *bp)
1346 if (((bp->b_flags & B_INVAL) == 0 && BUF_ISLOCKED(bp)) ||
1347 ((bp->b_flags & (B_DELWRI | B_INVAL)) == B_DELWRI))
1353 * Shutdown the system cleanly to prepare for reboot, halt, or power off.
1356 bufshutdown(int show_busybufs)
1358 static int first_buf_printf = 1;
1360 int i, iter, nbusy, pbusy;
1366 * Sync filesystems for shutdown
1368 wdog_kern_pat(WD_LASTVAL);
1369 kern_sync(curthread);
1372 * With soft updates, some buffers that are
1373 * written will be remarked as dirty until other
1374 * buffers are written.
1376 for (iter = pbusy = 0; iter < 20; iter++) {
1378 for (i = nbuf - 1; i >= 0; i--) {
1384 if (first_buf_printf)
1385 printf("All buffers synced.");
1388 if (first_buf_printf) {
1389 printf("Syncing disks, buffers remaining... ");
1390 first_buf_printf = 0;
1392 printf("%d ", nbusy);
1397 wdog_kern_pat(WD_LASTVAL);
1398 kern_sync(curthread);
1402 * Spin for a while to allow interrupt threads to run.
1404 DELAY(50000 * iter);
1407 * Context switch several times to allow interrupt
1410 for (subiter = 0; subiter < 50 * iter; subiter++) {
1411 thread_lock(curthread);
1419 * Count only busy local buffers to prevent forcing
1420 * a fsck if we're just a client of a wedged NFS server
1423 for (i = nbuf - 1; i >= 0; i--) {
1425 if (isbufbusy(bp)) {
1427 /* XXX: This is bogus. We should probably have a BO_REMOTE flag instead */
1428 if (bp->b_dev == NULL) {
1429 TAILQ_REMOVE(&mountlist,
1430 bp->b_vp->v_mount, mnt_list);
1435 if (show_busybufs > 0) {
1437 "%d: buf:%p, vnode:%p, flags:%0x, blkno:%jd, lblkno:%jd, buflock:",
1438 nbusy, bp, bp->b_vp, bp->b_flags,
1439 (intmax_t)bp->b_blkno,
1440 (intmax_t)bp->b_lblkno);
1441 BUF_LOCKPRINTINFO(bp);
1442 if (show_busybufs > 1)
1450 * Failed to sync all blocks. Indicate this and don't
1451 * unmount filesystems (thus forcing an fsck on reboot).
1453 printf("Giving up on %d buffers\n", nbusy);
1454 DELAY(5000000); /* 5 seconds */
1457 if (!first_buf_printf)
1458 printf("Final sync complete\n");
1461 * Unmount filesystems and perform swapoff, to quiesce
1462 * the system as much as possible. In particular, no
1463 * I/O should be initiated from top levels since it
1464 * might be abruptly terminated by reset, or otherwise
1465 * erronously handled because other parts of the
1466 * system are disabled.
1468 * Swapoff before unmount, because file-backed swap is
1469 * non-operational after unmount of the underlying
1472 if (!KERNEL_PANICKED()) {
1477 DELAY(100000); /* wait for console output to finish */
1481 bpmap_qenter(struct buf *bp)
1484 BUF_CHECK_MAPPED(bp);
1487 * bp->b_data is relative to bp->b_offset, but
1488 * bp->b_offset may be offset into the first page.
1490 bp->b_data = (caddr_t)trunc_page((vm_offset_t)bp->b_data);
1491 pmap_qenter((vm_offset_t)bp->b_data, bp->b_pages, bp->b_npages);
1492 bp->b_data = (caddr_t)((vm_offset_t)bp->b_data |
1493 (vm_offset_t)(bp->b_offset & PAGE_MASK));
1496 static inline struct bufdomain *
1497 bufdomain(struct buf *bp)
1500 return (&bdomain[bp->b_domain]);
1503 static struct bufqueue *
1504 bufqueue(struct buf *bp)
1507 switch (bp->b_qindex) {
1510 case QUEUE_SENTINEL:
1515 return (&bufdomain(bp)->bd_dirtyq);
1517 return (&bufdomain(bp)->bd_subq[bp->b_subqueue]);
1521 panic("bufqueue(%p): Unhandled type %d\n", bp, bp->b_qindex);
1525 * Return the locked bufqueue that bp is a member of.
1527 static struct bufqueue *
1528 bufqueue_acquire(struct buf *bp)
1530 struct bufqueue *bq, *nbq;
1533 * bp can be pushed from a per-cpu queue to the
1534 * cleanq while we're waiting on the lock. Retry
1535 * if the queues don't match.
1553 * Insert the buffer into the appropriate free list. Requires a
1554 * locked buffer on entry and buffer is unlocked before return.
1557 binsfree(struct buf *bp, int qindex)
1559 struct bufdomain *bd;
1560 struct bufqueue *bq;
1562 KASSERT(qindex == QUEUE_CLEAN || qindex == QUEUE_DIRTY,
1563 ("binsfree: Invalid qindex %d", qindex));
1564 BUF_ASSERT_XLOCKED(bp);
1567 * Handle delayed bremfree() processing.
1569 if (bp->b_flags & B_REMFREE) {
1570 if (bp->b_qindex == qindex) {
1571 bp->b_flags |= B_REUSE;
1572 bp->b_flags &= ~B_REMFREE;
1576 bq = bufqueue_acquire(bp);
1581 if (qindex == QUEUE_CLEAN) {
1582 if (bd->bd_lim != 0)
1583 bq = &bd->bd_subq[PCPU_GET(cpuid)];
1587 bq = &bd->bd_dirtyq;
1588 bq_insert(bq, bp, true);
1594 * Free a buffer to the buf zone once it no longer has valid contents.
1597 buf_free(struct buf *bp)
1600 if (bp->b_flags & B_REMFREE)
1602 if (bp->b_vflags & BV_BKGRDINPROG)
1603 panic("losing buffer 1");
1604 if (bp->b_rcred != NOCRED) {
1605 crfree(bp->b_rcred);
1606 bp->b_rcred = NOCRED;
1608 if (bp->b_wcred != NOCRED) {
1609 crfree(bp->b_wcred);
1610 bp->b_wcred = NOCRED;
1612 if (!LIST_EMPTY(&bp->b_dep))
1615 atomic_add_int(&bufdomain(bp)->bd_freebuffers, 1);
1616 MPASS((bp->b_flags & B_MAXPHYS) == 0);
1618 uma_zfree(buf_zone, bp);
1624 * Import bufs into the uma cache from the buf list. The system still
1625 * expects a static array of bufs and much of the synchronization
1626 * around bufs assumes type stable storage. As a result, UMA is used
1627 * only as a per-cpu cache of bufs still maintained on a global list.
1630 buf_import(void *arg, void **store, int cnt, int domain, int flags)
1636 for (i = 0; i < cnt; i++) {
1637 bp = TAILQ_FIRST(&bqempty.bq_queue);
1640 bq_remove(&bqempty, bp);
1643 BQ_UNLOCK(&bqempty);
1651 * Release bufs from the uma cache back to the buffer queues.
1654 buf_release(void *arg, void **store, int cnt)
1656 struct bufqueue *bq;
1662 for (i = 0; i < cnt; i++) {
1664 /* Inline bq_insert() to batch locking. */
1665 TAILQ_INSERT_TAIL(&bq->bq_queue, bp, b_freelist);
1666 bp->b_flags &= ~(B_AGE | B_REUSE);
1668 bp->b_qindex = bq->bq_index;
1676 * Allocate an empty buffer header.
1679 buf_alloc(struct bufdomain *bd)
1682 int freebufs, error;
1685 * We can only run out of bufs in the buf zone if the average buf
1686 * is less than BKVASIZE. In this case the actual wait/block will
1687 * come from buf_reycle() failing to flush one of these small bufs.
1690 freebufs = atomic_fetchadd_int(&bd->bd_freebuffers, -1);
1692 bp = uma_zalloc(buf_zone, M_NOWAIT);
1694 atomic_add_int(&bd->bd_freebuffers, 1);
1695 bufspace_daemon_wakeup(bd);
1696 counter_u64_add(numbufallocfails, 1);
1700 * Wake-up the bufspace daemon on transition below threshold.
1702 if (freebufs == bd->bd_lofreebuffers)
1703 bufspace_daemon_wakeup(bd);
1705 error = BUF_LOCK(bp, LK_EXCLUSIVE, NULL);
1706 KASSERT(error == 0, ("%s: BUF_LOCK on free buf %p: %d.", __func__, bp,
1710 KASSERT(bp->b_vp == NULL,
1711 ("bp: %p still has vnode %p.", bp, bp->b_vp));
1712 KASSERT((bp->b_flags & (B_DELWRI | B_NOREUSE)) == 0,
1713 ("invalid buffer %p flags %#x", bp, bp->b_flags));
1714 KASSERT((bp->b_xflags & (BX_VNCLEAN|BX_VNDIRTY)) == 0,
1715 ("bp: %p still on a buffer list. xflags %X", bp, bp->b_xflags));
1716 KASSERT(bp->b_npages == 0,
1717 ("bp: %p still has %d vm pages\n", bp, bp->b_npages));
1718 KASSERT(bp->b_kvasize == 0, ("bp: %p still has kva\n", bp));
1719 KASSERT(bp->b_bufsize == 0, ("bp: %p still has bufspace\n", bp));
1720 MPASS((bp->b_flags & B_MAXPHYS) == 0);
1722 bp->b_domain = BD_DOMAIN(bd);
1728 bp->b_blkno = bp->b_lblkno = 0;
1729 bp->b_offset = NOOFFSET;
1735 bp->b_dirtyoff = bp->b_dirtyend = 0;
1736 bp->b_bufobj = NULL;
1737 bp->b_data = bp->b_kvabase = unmapped_buf;
1738 bp->b_fsprivate1 = NULL;
1739 bp->b_fsprivate2 = NULL;
1740 bp->b_fsprivate3 = NULL;
1741 LIST_INIT(&bp->b_dep);
1749 * Free a buffer from the given bufqueue. kva controls whether the
1750 * freed buf must own some kva resources. This is used for
1754 buf_recycle(struct bufdomain *bd, bool kva)
1756 struct bufqueue *bq;
1757 struct buf *bp, *nbp;
1760 counter_u64_add(bufdefragcnt, 1);
1764 KASSERT(BQ_LOCKPTR(bq) == BD_LOCKPTR(bd),
1765 ("buf_recycle: Locks don't match"));
1766 nbp = TAILQ_FIRST(&bq->bq_queue);
1769 * Run scan, possibly freeing data and/or kva mappings on the fly
1772 while ((bp = nbp) != NULL) {
1774 * Calculate next bp (we can only use it if we do not
1775 * release the bqlock).
1777 nbp = TAILQ_NEXT(bp, b_freelist);
1780 * If we are defragging then we need a buffer with
1781 * some kva to reclaim.
1783 if (kva && bp->b_kvasize == 0)
1786 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0)
1790 * Implement a second chance algorithm for frequently
1793 if ((bp->b_flags & B_REUSE) != 0) {
1794 TAILQ_REMOVE(&bq->bq_queue, bp, b_freelist);
1795 TAILQ_INSERT_TAIL(&bq->bq_queue, bp, b_freelist);
1796 bp->b_flags &= ~B_REUSE;
1802 * Skip buffers with background writes in progress.
1804 if ((bp->b_vflags & BV_BKGRDINPROG) != 0) {
1809 KASSERT(bp->b_qindex == QUEUE_CLEAN,
1810 ("buf_recycle: inconsistent queue %d bp %p",
1812 KASSERT(bp->b_domain == BD_DOMAIN(bd),
1813 ("getnewbuf: queue domain %d doesn't match request %d",
1814 bp->b_domain, (int)BD_DOMAIN(bd)));
1816 * NOTE: nbp is now entirely invalid. We can only restart
1817 * the scan from this point on.
1823 * Requeue the background write buffer with error and
1826 if ((bp->b_vflags & BV_BKGRDERR) != 0) {
1829 nbp = TAILQ_FIRST(&bq->bq_queue);
1832 bp->b_flags |= B_INVAL;
1845 * Mark the buffer for removal from the appropriate free list.
1849 bremfree(struct buf *bp)
1852 CTR3(KTR_BUF, "bremfree(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
1853 KASSERT((bp->b_flags & B_REMFREE) == 0,
1854 ("bremfree: buffer %p already marked for delayed removal.", bp));
1855 KASSERT(bp->b_qindex != QUEUE_NONE,
1856 ("bremfree: buffer %p not on a queue.", bp));
1857 BUF_ASSERT_XLOCKED(bp);
1859 bp->b_flags |= B_REMFREE;
1865 * Force an immediate removal from a free list. Used only in nfs when
1866 * it abuses the b_freelist pointer.
1869 bremfreef(struct buf *bp)
1871 struct bufqueue *bq;
1873 bq = bufqueue_acquire(bp);
1879 bq_init(struct bufqueue *bq, int qindex, int subqueue, const char *lockname)
1882 mtx_init(&bq->bq_lock, lockname, NULL, MTX_DEF);
1883 TAILQ_INIT(&bq->bq_queue);
1885 bq->bq_index = qindex;
1886 bq->bq_subqueue = subqueue;
1890 bd_init(struct bufdomain *bd)
1894 bd->bd_cleanq = &bd->bd_subq[mp_maxid + 1];
1895 bq_init(bd->bd_cleanq, QUEUE_CLEAN, mp_maxid + 1, "bufq clean lock");
1896 bq_init(&bd->bd_dirtyq, QUEUE_DIRTY, -1, "bufq dirty lock");
1897 for (i = 0; i <= mp_maxid; i++)
1898 bq_init(&bd->bd_subq[i], QUEUE_CLEAN, i,
1899 "bufq clean subqueue lock");
1900 mtx_init(&bd->bd_run_lock, "bufspace daemon run lock", NULL, MTX_DEF);
1906 * Removes a buffer from the free list, must be called with the
1907 * correct qlock held.
1910 bq_remove(struct bufqueue *bq, struct buf *bp)
1913 CTR3(KTR_BUF, "bq_remove(%p) vp %p flags %X",
1914 bp, bp->b_vp, bp->b_flags);
1915 KASSERT(bp->b_qindex != QUEUE_NONE,
1916 ("bq_remove: buffer %p not on a queue.", bp));
1917 KASSERT(bufqueue(bp) == bq,
1918 ("bq_remove: Remove buffer %p from wrong queue.", bp));
1920 BQ_ASSERT_LOCKED(bq);
1921 if (bp->b_qindex != QUEUE_EMPTY) {
1922 BUF_ASSERT_XLOCKED(bp);
1924 KASSERT(bq->bq_len >= 1,
1925 ("queue %d underflow", bp->b_qindex));
1926 TAILQ_REMOVE(&bq->bq_queue, bp, b_freelist);
1928 bp->b_qindex = QUEUE_NONE;
1929 bp->b_flags &= ~(B_REMFREE | B_REUSE);
1933 bd_flush(struct bufdomain *bd, struct bufqueue *bq)
1937 BQ_ASSERT_LOCKED(bq);
1938 if (bq != bd->bd_cleanq) {
1940 while ((bp = TAILQ_FIRST(&bq->bq_queue)) != NULL) {
1941 TAILQ_REMOVE(&bq->bq_queue, bp, b_freelist);
1942 TAILQ_INSERT_TAIL(&bd->bd_cleanq->bq_queue, bp,
1944 bp->b_subqueue = bd->bd_cleanq->bq_subqueue;
1946 bd->bd_cleanq->bq_len += bq->bq_len;
1949 if (bd->bd_wanted) {
1951 wakeup(&bd->bd_wanted);
1953 if (bq != bd->bd_cleanq)
1958 bd_flushall(struct bufdomain *bd)
1960 struct bufqueue *bq;
1964 if (bd->bd_lim == 0)
1967 for (i = 0; i <= mp_maxid; i++) {
1968 bq = &bd->bd_subq[i];
1969 if (bq->bq_len == 0)
1981 bq_insert(struct bufqueue *bq, struct buf *bp, bool unlock)
1983 struct bufdomain *bd;
1985 if (bp->b_qindex != QUEUE_NONE)
1986 panic("bq_insert: free buffer %p onto another queue?", bp);
1989 if (bp->b_flags & B_AGE) {
1990 /* Place this buf directly on the real queue. */
1991 if (bq->bq_index == QUEUE_CLEAN)
1994 TAILQ_INSERT_HEAD(&bq->bq_queue, bp, b_freelist);
1997 TAILQ_INSERT_TAIL(&bq->bq_queue, bp, b_freelist);
1999 bp->b_flags &= ~(B_AGE | B_REUSE);
2001 bp->b_qindex = bq->bq_index;
2002 bp->b_subqueue = bq->bq_subqueue;
2005 * Unlock before we notify so that we don't wakeup a waiter that
2006 * fails a trylock on the buf and sleeps again.
2011 if (bp->b_qindex == QUEUE_CLEAN) {
2013 * Flush the per-cpu queue and notify any waiters.
2015 if (bd->bd_wanted || (bq != bd->bd_cleanq &&
2016 bq->bq_len >= bd->bd_lim))
2025 * Free the kva allocation for a buffer.
2029 bufkva_free(struct buf *bp)
2033 if (bp->b_kvasize == 0) {
2034 KASSERT(bp->b_kvabase == unmapped_buf &&
2035 bp->b_data == unmapped_buf,
2036 ("Leaked KVA space on %p", bp));
2037 } else if (buf_mapped(bp))
2038 BUF_CHECK_MAPPED(bp);
2040 BUF_CHECK_UNMAPPED(bp);
2042 if (bp->b_kvasize == 0)
2045 vmem_free(buffer_arena, (vm_offset_t)bp->b_kvabase, bp->b_kvasize);
2046 counter_u64_add(bufkvaspace, -bp->b_kvasize);
2047 counter_u64_add(buffreekvacnt, 1);
2048 bp->b_data = bp->b_kvabase = unmapped_buf;
2055 * Allocate the buffer KVA and set b_kvasize and b_kvabase.
2058 bufkva_alloc(struct buf *bp, int maxsize, int gbflags)
2063 KASSERT((gbflags & GB_UNMAPPED) == 0 || (gbflags & GB_KVAALLOC) != 0,
2064 ("Invalid gbflags 0x%x in %s", gbflags, __func__));
2065 MPASS((bp->b_flags & B_MAXPHYS) == 0);
2066 KASSERT(maxsize <= maxbcachebuf,
2067 ("bufkva_alloc kva too large %d %u", maxsize, maxbcachebuf));
2072 error = vmem_alloc(buffer_arena, maxsize, M_BESTFIT | M_NOWAIT, &addr);
2075 * Buffer map is too fragmented. Request the caller
2076 * to defragment the map.
2080 bp->b_kvabase = (caddr_t)addr;
2081 bp->b_kvasize = maxsize;
2082 counter_u64_add(bufkvaspace, bp->b_kvasize);
2083 if ((gbflags & GB_UNMAPPED) != 0) {
2084 bp->b_data = unmapped_buf;
2085 BUF_CHECK_UNMAPPED(bp);
2087 bp->b_data = bp->b_kvabase;
2088 BUF_CHECK_MAPPED(bp);
2096 * Reclaim buffer kva by freeing buffers holding kva. This is a vmem
2097 * callback that fires to avoid returning failure.
2100 bufkva_reclaim(vmem_t *vmem, int flags)
2107 for (i = 0; i < 5; i++) {
2108 for (q = 0; q < buf_domains; q++)
2109 if (buf_recycle(&bdomain[q], true) != 0)
2118 * Attempt to initiate asynchronous I/O on read-ahead blocks. We must
2119 * clear BIO_ERROR and B_INVAL prior to initiating I/O . If B_CACHE is set,
2120 * the buffer is valid and we do not have to do anything.
2123 breada(struct vnode * vp, daddr_t * rablkno, int * rabsize, int cnt,
2124 struct ucred * cred, int flags, void (*ckhashfunc)(struct buf *))
2132 for (i = 0; i < cnt; i++, rablkno++, rabsize++) {
2133 if (inmem(vp, *rablkno))
2135 rabp = getblk(vp, *rablkno, *rabsize, 0, 0, 0);
2136 if ((rabp->b_flags & B_CACHE) != 0) {
2143 racct_add_buf(curproc, rabp, 0);
2144 PROC_UNLOCK(curproc);
2147 td->td_ru.ru_inblock++;
2148 rabp->b_flags |= B_ASYNC;
2149 rabp->b_flags &= ~B_INVAL;
2150 if ((flags & GB_CKHASH) != 0) {
2151 rabp->b_flags |= B_CKHASH;
2152 rabp->b_ckhashcalc = ckhashfunc;
2154 rabp->b_ioflags &= ~BIO_ERROR;
2155 rabp->b_iocmd = BIO_READ;
2156 if (rabp->b_rcred == NOCRED && cred != NOCRED)
2157 rabp->b_rcred = crhold(cred);
2158 vfs_busy_pages(rabp, 0);
2160 rabp->b_iooffset = dbtob(rabp->b_blkno);
2166 * Entry point for bread() and breadn() via #defines in sys/buf.h.
2168 * Get a buffer with the specified data. Look in the cache first. We
2169 * must clear BIO_ERROR and B_INVAL prior to initiating I/O. If B_CACHE
2170 * is set, the buffer is valid and we do not have to do anything, see
2171 * getblk(). Also starts asynchronous I/O on read-ahead blocks.
2173 * Always return a NULL buffer pointer (in bpp) when returning an error.
2175 * The blkno parameter is the logical block being requested. Normally
2176 * the mapping of logical block number to disk block address is done
2177 * by calling VOP_BMAP(). However, if the mapping is already known, the
2178 * disk block address can be passed using the dblkno parameter. If the
2179 * disk block address is not known, then the same value should be passed
2180 * for blkno and dblkno.
2183 breadn_flags(struct vnode *vp, daddr_t blkno, daddr_t dblkno, int size,
2184 daddr_t *rablkno, int *rabsize, int cnt, struct ucred *cred, int flags,
2185 void (*ckhashfunc)(struct buf *), struct buf **bpp)
2189 int error, readwait, rv;
2191 CTR3(KTR_BUF, "breadn(%p, %jd, %d)", vp, blkno, size);
2194 * Can only return NULL if GB_LOCK_NOWAIT or GB_SPARSE flags
2197 error = getblkx(vp, blkno, dblkno, size, 0, 0, flags, &bp);
2202 KASSERT(blkno == bp->b_lblkno,
2203 ("getblkx returned buffer for blkno %jd instead of blkno %jd",
2204 (intmax_t)bp->b_lblkno, (intmax_t)blkno));
2205 flags &= ~GB_NOSPARSE;
2209 * If not found in cache, do some I/O
2212 if ((bp->b_flags & B_CACHE) == 0) {
2215 PROC_LOCK(td->td_proc);
2216 racct_add_buf(td->td_proc, bp, 0);
2217 PROC_UNLOCK(td->td_proc);
2220 td->td_ru.ru_inblock++;
2221 bp->b_iocmd = BIO_READ;
2222 bp->b_flags &= ~B_INVAL;
2223 if ((flags & GB_CKHASH) != 0) {
2224 bp->b_flags |= B_CKHASH;
2225 bp->b_ckhashcalc = ckhashfunc;
2227 if ((flags & GB_CVTENXIO) != 0)
2228 bp->b_xflags |= BX_CVTENXIO;
2229 bp->b_ioflags &= ~BIO_ERROR;
2230 if (bp->b_rcred == NOCRED && cred != NOCRED)
2231 bp->b_rcred = crhold(cred);
2232 vfs_busy_pages(bp, 0);
2233 bp->b_iooffset = dbtob(bp->b_blkno);
2239 * Attempt to initiate asynchronous I/O on read-ahead blocks.
2241 breada(vp, rablkno, rabsize, cnt, cred, flags, ckhashfunc);
2255 * Write, release buffer on completion. (Done by iodone
2256 * if async). Do not bother writing anything if the buffer
2259 * Note that we set B_CACHE here, indicating that buffer is
2260 * fully valid and thus cacheable. This is true even of NFS
2261 * now so we set it generally. This could be set either here
2262 * or in biodone() since the I/O is synchronous. We put it
2266 bufwrite(struct buf *bp)
2273 CTR3(KTR_BUF, "bufwrite(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
2274 if ((bp->b_bufobj->bo_flag & BO_DEAD) != 0) {
2275 bp->b_flags |= B_INVAL | B_RELBUF;
2276 bp->b_flags &= ~B_CACHE;
2280 if (bp->b_flags & B_INVAL) {
2285 if (bp->b_flags & B_BARRIER)
2286 atomic_add_long(&barrierwrites, 1);
2288 oldflags = bp->b_flags;
2290 KASSERT(!(bp->b_vflags & BV_BKGRDINPROG),
2291 ("FFS background buffer should not get here %p", bp));
2295 vp_md = vp->v_vflag & VV_MD;
2300 * Mark the buffer clean. Increment the bufobj write count
2301 * before bundirty() call, to prevent other thread from seeing
2302 * empty dirty list and zero counter for writes in progress,
2303 * falsely indicating that the bufobj is clean.
2305 bufobj_wref(bp->b_bufobj);
2308 bp->b_flags &= ~B_DONE;
2309 bp->b_ioflags &= ~BIO_ERROR;
2310 bp->b_flags |= B_CACHE;
2311 bp->b_iocmd = BIO_WRITE;
2313 vfs_busy_pages(bp, 1);
2316 * Normal bwrites pipeline writes
2318 bp->b_runningbufspace = bp->b_bufsize;
2319 space = atomic_fetchadd_long(&runningbufspace, bp->b_runningbufspace);
2324 racct_add_buf(curproc, bp, 1);
2325 PROC_UNLOCK(curproc);
2328 curthread->td_ru.ru_oublock++;
2329 if (oldflags & B_ASYNC)
2331 bp->b_iooffset = dbtob(bp->b_blkno);
2332 buf_track(bp, __func__);
2335 if ((oldflags & B_ASYNC) == 0) {
2336 int rtval = bufwait(bp);
2339 } else if (space > hirunningspace) {
2341 * don't allow the async write to saturate the I/O
2342 * system. We will not deadlock here because
2343 * we are blocking waiting for I/O that is already in-progress
2344 * to complete. We do not block here if it is the update
2345 * or syncer daemon trying to clean up as that can lead
2348 if ((curthread->td_pflags & TDP_NORUNNINGBUF) == 0 && !vp_md)
2349 waitrunningbufspace();
2356 bufbdflush(struct bufobj *bo, struct buf *bp)
2359 struct bufdomain *bd;
2361 bd = &bdomain[bo->bo_domain];
2362 if (bo->bo_dirty.bv_cnt > bd->bd_dirtybufthresh + 10) {
2363 (void) VOP_FSYNC(bp->b_vp, MNT_NOWAIT, curthread);
2365 } else if (bo->bo_dirty.bv_cnt > bd->bd_dirtybufthresh) {
2368 * Try to find a buffer to flush.
2370 TAILQ_FOREACH(nbp, &bo->bo_dirty.bv_hd, b_bobufs) {
2371 if ((nbp->b_vflags & BV_BKGRDINPROG) ||
2373 LK_EXCLUSIVE | LK_NOWAIT, NULL))
2376 panic("bdwrite: found ourselves");
2378 /* Don't countdeps with the bo lock held. */
2379 if (buf_countdeps(nbp, 0)) {
2384 if (nbp->b_flags & B_CLUSTEROK) {
2385 vfs_bio_awrite(nbp);
2390 dirtybufferflushes++;
2399 * Delayed write. (Buffer is marked dirty). Do not bother writing
2400 * anything if the buffer is marked invalid.
2402 * Note that since the buffer must be completely valid, we can safely
2403 * set B_CACHE. In fact, we have to set B_CACHE here rather then in
2404 * biodone() in order to prevent getblk from writing the buffer
2405 * out synchronously.
2408 bdwrite(struct buf *bp)
2410 struct thread *td = curthread;
2414 CTR3(KTR_BUF, "bdwrite(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
2415 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp));
2416 KASSERT((bp->b_flags & B_BARRIER) == 0,
2417 ("Barrier request in delayed write %p", bp));
2419 if (bp->b_flags & B_INVAL) {
2425 * If we have too many dirty buffers, don't create any more.
2426 * If we are wildly over our limit, then force a complete
2427 * cleanup. Otherwise, just keep the situation from getting
2428 * out of control. Note that we have to avoid a recursive
2429 * disaster and not try to clean up after our own cleanup!
2433 if ((td->td_pflags & (TDP_COWINPROGRESS|TDP_INBDFLUSH)) == 0) {
2434 td->td_pflags |= TDP_INBDFLUSH;
2436 td->td_pflags &= ~TDP_INBDFLUSH;
2442 * Set B_CACHE, indicating that the buffer is fully valid. This is
2443 * true even of NFS now.
2445 bp->b_flags |= B_CACHE;
2448 * This bmap keeps the system from needing to do the bmap later,
2449 * perhaps when the system is attempting to do a sync. Since it
2450 * is likely that the indirect block -- or whatever other datastructure
2451 * that the filesystem needs is still in memory now, it is a good
2452 * thing to do this. Note also, that if the pageout daemon is
2453 * requesting a sync -- there might not be enough memory to do
2454 * the bmap then... So, this is important to do.
2456 if (vp->v_type != VCHR && bp->b_lblkno == bp->b_blkno) {
2457 VOP_BMAP(vp, bp->b_lblkno, NULL, &bp->b_blkno, NULL, NULL);
2460 buf_track(bp, __func__);
2463 * Set the *dirty* buffer range based upon the VM system dirty
2466 * Mark the buffer pages as clean. We need to do this here to
2467 * satisfy the vnode_pager and the pageout daemon, so that it
2468 * thinks that the pages have been "cleaned". Note that since
2469 * the pages are in a delayed write buffer -- the VFS layer
2470 * "will" see that the pages get written out on the next sync,
2471 * or perhaps the cluster will be completed.
2473 vfs_clean_pages_dirty_buf(bp);
2477 * note: we cannot initiate I/O from a bdwrite even if we wanted to,
2478 * due to the softdep code.
2485 * Turn buffer into delayed write request. We must clear BIO_READ and
2486 * B_RELBUF, and we must set B_DELWRI. We reassign the buffer to
2487 * itself to properly update it in the dirty/clean lists. We mark it
2488 * B_DONE to ensure that any asynchronization of the buffer properly
2489 * clears B_DONE ( else a panic will occur later ).
2491 * bdirty() is kinda like bdwrite() - we have to clear B_INVAL which
2492 * might have been set pre-getblk(). Unlike bwrite/bdwrite, bdirty()
2493 * should only be called if the buffer is known-good.
2495 * Since the buffer is not on a queue, we do not update the numfreebuffers
2498 * The buffer must be on QUEUE_NONE.
2501 bdirty(struct buf *bp)
2504 CTR3(KTR_BUF, "bdirty(%p) vp %p flags %X",
2505 bp, bp->b_vp, bp->b_flags);
2506 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp));
2507 KASSERT(bp->b_flags & B_REMFREE || bp->b_qindex == QUEUE_NONE,
2508 ("bdirty: buffer %p still on queue %d", bp, bp->b_qindex));
2509 bp->b_flags &= ~(B_RELBUF);
2510 bp->b_iocmd = BIO_WRITE;
2512 if ((bp->b_flags & B_DELWRI) == 0) {
2513 bp->b_flags |= /* XXX B_DONE | */ B_DELWRI;
2522 * Clear B_DELWRI for buffer.
2524 * Since the buffer is not on a queue, we do not update the numfreebuffers
2527 * The buffer must be on QUEUE_NONE.
2531 bundirty(struct buf *bp)
2534 CTR3(KTR_BUF, "bundirty(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
2535 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp));
2536 KASSERT(bp->b_flags & B_REMFREE || bp->b_qindex == QUEUE_NONE,
2537 ("bundirty: buffer %p still on queue %d", bp, bp->b_qindex));
2539 if (bp->b_flags & B_DELWRI) {
2540 bp->b_flags &= ~B_DELWRI;
2545 * Since it is now being written, we can clear its deferred write flag.
2547 bp->b_flags &= ~B_DEFERRED;
2553 * Asynchronous write. Start output on a buffer, but do not wait for
2554 * it to complete. The buffer is released when the output completes.
2556 * bwrite() ( or the VOP routine anyway ) is responsible for handling
2557 * B_INVAL buffers. Not us.
2560 bawrite(struct buf *bp)
2563 bp->b_flags |= B_ASYNC;
2570 * Asynchronous barrier write. Start output on a buffer, but do not
2571 * wait for it to complete. Place a write barrier after this write so
2572 * that this buffer and all buffers written before it are committed to
2573 * the disk before any buffers written after this write are committed
2574 * to the disk. The buffer is released when the output completes.
2577 babarrierwrite(struct buf *bp)
2580 bp->b_flags |= B_ASYNC | B_BARRIER;
2587 * Synchronous barrier write. Start output on a buffer and wait for
2588 * it to complete. Place a write barrier after this write so that
2589 * this buffer and all buffers written before it are committed to
2590 * the disk before any buffers written after this write are committed
2591 * to the disk. The buffer is released when the output completes.
2594 bbarrierwrite(struct buf *bp)
2597 bp->b_flags |= B_BARRIER;
2598 return (bwrite(bp));
2604 * Called prior to the locking of any vnodes when we are expecting to
2605 * write. We do not want to starve the buffer cache with too many
2606 * dirty buffers so we block here. By blocking prior to the locking
2607 * of any vnodes we attempt to avoid the situation where a locked vnode
2608 * prevents the various system daemons from flushing related buffers.
2614 if (buf_dirty_count_severe()) {
2615 mtx_lock(&bdirtylock);
2616 while (buf_dirty_count_severe()) {
2618 msleep(&bdirtywait, &bdirtylock, (PRIBIO + 4),
2621 mtx_unlock(&bdirtylock);
2626 * Return true if we have too many dirty buffers.
2629 buf_dirty_count_severe(void)
2632 return (!BIT_EMPTY(BUF_DOMAINS, &bdhidirty));
2638 * Release a busy buffer and, if requested, free its resources. The
2639 * buffer will be stashed in the appropriate bufqueue[] allowing it
2640 * to be accessed later as a cache entity or reused for other purposes.
2643 brelse(struct buf *bp)
2645 struct mount *v_mnt;
2649 * Many functions erroneously call brelse with a NULL bp under rare
2650 * error conditions. Simply return when called with a NULL bp.
2654 CTR3(KTR_BUF, "brelse(%p) vp %p flags %X",
2655 bp, bp->b_vp, bp->b_flags);
2656 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)),
2657 ("brelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp));
2658 KASSERT((bp->b_flags & B_VMIO) != 0 || (bp->b_flags & B_NOREUSE) == 0,
2659 ("brelse: non-VMIO buffer marked NOREUSE"));
2661 if (BUF_LOCKRECURSED(bp)) {
2663 * Do not process, in particular, do not handle the
2664 * B_INVAL/B_RELBUF and do not release to free list.
2670 if (bp->b_flags & B_MANAGED) {
2675 if (LIST_EMPTY(&bp->b_dep)) {
2676 bp->b_flags &= ~B_IOSTARTED;
2678 KASSERT((bp->b_flags & B_IOSTARTED) == 0,
2679 ("brelse: SU io not finished bp %p", bp));
2682 if ((bp->b_vflags & (BV_BKGRDINPROG | BV_BKGRDERR)) == BV_BKGRDERR) {
2683 BO_LOCK(bp->b_bufobj);
2684 bp->b_vflags &= ~BV_BKGRDERR;
2685 BO_UNLOCK(bp->b_bufobj);
2689 if (bp->b_iocmd == BIO_WRITE && (bp->b_ioflags & BIO_ERROR) &&
2690 (bp->b_flags & B_INVALONERR)) {
2692 * Forced invalidation of dirty buffer contents, to be used
2693 * after a failed write in the rare case that the loss of the
2694 * contents is acceptable. The buffer is invalidated and
2697 bp->b_flags |= B_INVAL | B_RELBUF | B_NOCACHE;
2698 bp->b_flags &= ~(B_ASYNC | B_CACHE);
2701 if (bp->b_iocmd == BIO_WRITE && (bp->b_ioflags & BIO_ERROR) &&
2702 (bp->b_error != ENXIO || !LIST_EMPTY(&bp->b_dep)) &&
2703 !(bp->b_flags & B_INVAL)) {
2705 * Failed write, redirty. All errors except ENXIO (which
2706 * means the device is gone) are treated as being
2709 * XXX Treating EIO as transient is not correct; the
2710 * contract with the local storage device drivers is that
2711 * they will only return EIO once the I/O is no longer
2712 * retriable. Network I/O also respects this through the
2713 * guarantees of TCP and/or the internal retries of NFS.
2714 * ENOMEM might be transient, but we also have no way of
2715 * knowing when its ok to retry/reschedule. In general,
2716 * this entire case should be made obsolete through better
2717 * error handling/recovery and resource scheduling.
2719 * Do this also for buffers that failed with ENXIO, but have
2720 * non-empty dependencies - the soft updates code might need
2721 * to access the buffer to untangle them.
2723 * Must clear BIO_ERROR to prevent pages from being scrapped.
2725 bp->b_ioflags &= ~BIO_ERROR;
2727 } else if ((bp->b_flags & (B_NOCACHE | B_INVAL)) ||
2728 (bp->b_ioflags & BIO_ERROR) || (bp->b_bufsize <= 0)) {
2730 * Either a failed read I/O, or we were asked to free or not
2731 * cache the buffer, or we failed to write to a device that's
2732 * no longer present.
2734 bp->b_flags |= B_INVAL;
2735 if (!LIST_EMPTY(&bp->b_dep))
2737 if (bp->b_flags & B_DELWRI)
2739 bp->b_flags &= ~(B_DELWRI | B_CACHE);
2740 if ((bp->b_flags & B_VMIO) == 0) {
2748 * We must clear B_RELBUF if B_DELWRI is set. If vfs_vmio_truncate()
2749 * is called with B_DELWRI set, the underlying pages may wind up
2750 * getting freed causing a previous write (bdwrite()) to get 'lost'
2751 * because pages associated with a B_DELWRI bp are marked clean.
2753 * We still allow the B_INVAL case to call vfs_vmio_truncate(), even
2754 * if B_DELWRI is set.
2756 if (bp->b_flags & B_DELWRI)
2757 bp->b_flags &= ~B_RELBUF;
2760 * VMIO buffer rundown. It is not very necessary to keep a VMIO buffer
2761 * constituted, not even NFS buffers now. Two flags effect this. If
2762 * B_INVAL, the struct buf is invalidated but the VM object is kept
2763 * around ( i.e. so it is trivial to reconstitute the buffer later ).
2765 * If BIO_ERROR or B_NOCACHE is set, pages in the VM object will be
2766 * invalidated. BIO_ERROR cannot be set for a failed write unless the
2767 * buffer is also B_INVAL because it hits the re-dirtying code above.
2769 * Normally we can do this whether a buffer is B_DELWRI or not. If
2770 * the buffer is an NFS buffer, it is tracking piecemeal writes or
2771 * the commit state and we cannot afford to lose the buffer. If the
2772 * buffer has a background write in progress, we need to keep it
2773 * around to prevent it from being reconstituted and starting a second
2777 v_mnt = bp->b_vp != NULL ? bp->b_vp->v_mount : NULL;
2779 if ((bp->b_flags & B_VMIO) && (bp->b_flags & B_NOCACHE ||
2780 (bp->b_ioflags & BIO_ERROR && bp->b_iocmd == BIO_READ)) &&
2781 (v_mnt == NULL || (v_mnt->mnt_vfc->vfc_flags & VFCF_NETWORK) == 0 ||
2782 vn_isdisk(bp->b_vp) || (bp->b_flags & B_DELWRI) == 0)) {
2783 vfs_vmio_invalidate(bp);
2787 if ((bp->b_flags & (B_INVAL | B_RELBUF)) != 0 ||
2788 (bp->b_flags & (B_DELWRI | B_NOREUSE)) == B_NOREUSE) {
2790 bp->b_flags &= ~B_NOREUSE;
2791 if (bp->b_vp != NULL)
2796 * If the buffer has junk contents signal it and eventually
2797 * clean up B_DELWRI and diassociate the vnode so that gbincore()
2800 if (bp->b_bufsize == 0 || (bp->b_ioflags & BIO_ERROR) != 0 ||
2801 (bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF)) != 0)
2802 bp->b_flags |= B_INVAL;
2803 if (bp->b_flags & B_INVAL) {
2804 if (bp->b_flags & B_DELWRI)
2810 buf_track(bp, __func__);
2812 /* buffers with no memory */
2813 if (bp->b_bufsize == 0) {
2817 /* buffers with junk contents */
2818 if (bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF) ||
2819 (bp->b_ioflags & BIO_ERROR)) {
2820 bp->b_xflags &= ~(BX_BKGRDWRITE | BX_ALTDATA);
2821 if (bp->b_vflags & BV_BKGRDINPROG)
2822 panic("losing buffer 2");
2823 qindex = QUEUE_CLEAN;
2824 bp->b_flags |= B_AGE;
2825 /* remaining buffers */
2826 } else if (bp->b_flags & B_DELWRI)
2827 qindex = QUEUE_DIRTY;
2829 qindex = QUEUE_CLEAN;
2831 if ((bp->b_flags & B_DELWRI) == 0 && (bp->b_xflags & BX_VNDIRTY))
2832 panic("brelse: not dirty");
2834 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_RELBUF | B_DIRECT);
2835 bp->b_xflags &= ~(BX_CVTENXIO);
2836 /* binsfree unlocks bp. */
2837 binsfree(bp, qindex);
2841 * Release a buffer back to the appropriate queue but do not try to free
2842 * it. The buffer is expected to be used again soon.
2844 * bqrelse() is used by bdwrite() to requeue a delayed write, and used by
2845 * biodone() to requeue an async I/O on completion. It is also used when
2846 * known good buffers need to be requeued but we think we may need the data
2849 * XXX we should be able to leave the B_RELBUF hint set on completion.
2852 bqrelse(struct buf *bp)
2856 CTR3(KTR_BUF, "bqrelse(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
2857 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)),
2858 ("bqrelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp));
2860 qindex = QUEUE_NONE;
2861 if (BUF_LOCKRECURSED(bp)) {
2862 /* do not release to free list */
2866 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF);
2867 bp->b_xflags &= ~(BX_CVTENXIO);
2869 if (LIST_EMPTY(&bp->b_dep)) {
2870 bp->b_flags &= ~B_IOSTARTED;
2872 KASSERT((bp->b_flags & B_IOSTARTED) == 0,
2873 ("bqrelse: SU io not finished bp %p", bp));
2876 if (bp->b_flags & B_MANAGED) {
2877 if (bp->b_flags & B_REMFREE)
2882 /* buffers with stale but valid contents */
2883 if ((bp->b_flags & B_DELWRI) != 0 || (bp->b_vflags & (BV_BKGRDINPROG |
2884 BV_BKGRDERR)) == BV_BKGRDERR) {
2885 BO_LOCK(bp->b_bufobj);
2886 bp->b_vflags &= ~BV_BKGRDERR;
2887 BO_UNLOCK(bp->b_bufobj);
2888 qindex = QUEUE_DIRTY;
2890 if ((bp->b_flags & B_DELWRI) == 0 &&
2891 (bp->b_xflags & BX_VNDIRTY))
2892 panic("bqrelse: not dirty");
2893 if ((bp->b_flags & B_NOREUSE) != 0) {
2897 qindex = QUEUE_CLEAN;
2899 buf_track(bp, __func__);
2900 /* binsfree unlocks bp. */
2901 binsfree(bp, qindex);
2905 buf_track(bp, __func__);
2911 * Complete I/O to a VMIO backed page. Validate the pages as appropriate,
2912 * restore bogus pages.
2915 vfs_vmio_iodone(struct buf *bp)
2920 struct vnode *vp __unused;
2921 int i, iosize, resid;
2924 obj = bp->b_bufobj->bo_object;
2925 KASSERT(blockcount_read(&obj->paging_in_progress) >= bp->b_npages,
2926 ("vfs_vmio_iodone: paging in progress(%d) < b_npages(%d)",
2927 blockcount_read(&obj->paging_in_progress), bp->b_npages));
2930 VNPASS(vp->v_holdcnt > 0, vp);
2931 VNPASS(vp->v_object != NULL, vp);
2933 foff = bp->b_offset;
2934 KASSERT(bp->b_offset != NOOFFSET,
2935 ("vfs_vmio_iodone: bp %p has no buffer offset", bp));
2938 iosize = bp->b_bcount - bp->b_resid;
2939 for (i = 0; i < bp->b_npages; i++) {
2940 resid = ((foff + PAGE_SIZE) & ~(off_t)PAGE_MASK) - foff;
2945 * cleanup bogus pages, restoring the originals
2948 if (m == bogus_page) {
2950 m = vm_page_relookup(obj, OFF_TO_IDX(foff));
2952 panic("biodone: page disappeared!");
2954 } else if ((bp->b_iocmd == BIO_READ) && resid > 0) {
2956 * In the write case, the valid and clean bits are
2957 * already changed correctly ( see bdwrite() ), so we
2958 * only need to do this here in the read case.
2960 KASSERT((m->dirty & vm_page_bits(foff & PAGE_MASK,
2961 resid)) == 0, ("vfs_vmio_iodone: page %p "
2962 "has unexpected dirty bits", m));
2963 vfs_page_set_valid(bp, foff, m);
2965 KASSERT(OFF_TO_IDX(foff) == m->pindex,
2966 ("vfs_vmio_iodone: foff(%jd)/pindex(%ju) mismatch",
2967 (intmax_t)foff, (uintmax_t)m->pindex));
2970 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK;
2973 vm_object_pip_wakeupn(obj, bp->b_npages);
2974 if (bogus && buf_mapped(bp)) {
2975 BUF_CHECK_MAPPED(bp);
2976 pmap_qenter(trunc_page((vm_offset_t)bp->b_data),
2977 bp->b_pages, bp->b_npages);
2982 * Perform page invalidation when a buffer is released. The fully invalid
2983 * pages will be reclaimed later in vfs_vmio_truncate().
2986 vfs_vmio_invalidate(struct buf *bp)
2990 int flags, i, resid, poffset, presid;
2992 if (buf_mapped(bp)) {
2993 BUF_CHECK_MAPPED(bp);
2994 pmap_qremove(trunc_page((vm_offset_t)bp->b_data), bp->b_npages);
2996 BUF_CHECK_UNMAPPED(bp);
2998 * Get the base offset and length of the buffer. Note that
2999 * in the VMIO case if the buffer block size is not
3000 * page-aligned then b_data pointer may not be page-aligned.
3001 * But our b_pages[] array *IS* page aligned.
3003 * block sizes less then DEV_BSIZE (usually 512) are not
3004 * supported due to the page granularity bits (m->valid,
3005 * m->dirty, etc...).
3007 * See man buf(9) for more information
3009 flags = (bp->b_flags & B_NOREUSE) != 0 ? VPR_NOREUSE : 0;
3010 obj = bp->b_bufobj->bo_object;
3011 resid = bp->b_bufsize;
3012 poffset = bp->b_offset & PAGE_MASK;
3013 VM_OBJECT_WLOCK(obj);
3014 for (i = 0; i < bp->b_npages; i++) {
3016 if (m == bogus_page)
3017 panic("vfs_vmio_invalidate: Unexpected bogus page.");
3018 bp->b_pages[i] = NULL;
3020 presid = resid > (PAGE_SIZE - poffset) ?
3021 (PAGE_SIZE - poffset) : resid;
3022 KASSERT(presid >= 0, ("brelse: extra page"));
3023 vm_page_busy_acquire(m, VM_ALLOC_SBUSY);
3024 if (pmap_page_wired_mappings(m) == 0)
3025 vm_page_set_invalid(m, poffset, presid);
3027 vm_page_release_locked(m, flags);
3031 VM_OBJECT_WUNLOCK(obj);
3036 * Page-granular truncation of an existing VMIO buffer.
3039 vfs_vmio_truncate(struct buf *bp, int desiredpages)
3045 if (bp->b_npages == desiredpages)
3048 if (buf_mapped(bp)) {
3049 BUF_CHECK_MAPPED(bp);
3050 pmap_qremove((vm_offset_t)trunc_page((vm_offset_t)bp->b_data) +
3051 (desiredpages << PAGE_SHIFT), bp->b_npages - desiredpages);
3053 BUF_CHECK_UNMAPPED(bp);
3056 * The object lock is needed only if we will attempt to free pages.
3058 flags = (bp->b_flags & B_NOREUSE) != 0 ? VPR_NOREUSE : 0;
3059 if ((bp->b_flags & B_DIRECT) != 0) {
3060 flags |= VPR_TRYFREE;
3061 obj = bp->b_bufobj->bo_object;
3062 VM_OBJECT_WLOCK(obj);
3066 for (i = desiredpages; i < bp->b_npages; i++) {
3068 KASSERT(m != bogus_page, ("allocbuf: bogus page found"));
3069 bp->b_pages[i] = NULL;
3071 vm_page_release_locked(m, flags);
3073 vm_page_release(m, flags);
3076 VM_OBJECT_WUNLOCK(obj);
3077 bp->b_npages = desiredpages;
3081 * Byte granular extension of VMIO buffers.
3084 vfs_vmio_extend(struct buf *bp, int desiredpages, int size)
3087 * We are growing the buffer, possibly in a
3088 * byte-granular fashion.
3096 * Step 1, bring in the VM pages from the object, allocating
3097 * them if necessary. We must clear B_CACHE if these pages
3098 * are not valid for the range covered by the buffer.
3100 obj = bp->b_bufobj->bo_object;
3101 if (bp->b_npages < desiredpages) {
3102 KASSERT(desiredpages <= atop(maxbcachebuf),
3103 ("vfs_vmio_extend past maxbcachebuf %p %d %u",
3104 bp, desiredpages, maxbcachebuf));
3107 * We must allocate system pages since blocking
3108 * here could interfere with paging I/O, no
3109 * matter which process we are.
3111 * Only exclusive busy can be tested here.
3112 * Blocking on shared busy might lead to
3113 * deadlocks once allocbuf() is called after
3114 * pages are vfs_busy_pages().
3116 (void)vm_page_grab_pages_unlocked(obj,
3117 OFF_TO_IDX(bp->b_offset) + bp->b_npages,
3118 VM_ALLOC_SYSTEM | VM_ALLOC_IGN_SBUSY |
3119 VM_ALLOC_NOBUSY | VM_ALLOC_WIRED,
3120 &bp->b_pages[bp->b_npages], desiredpages - bp->b_npages);
3121 bp->b_npages = desiredpages;
3125 * Step 2. We've loaded the pages into the buffer,
3126 * we have to figure out if we can still have B_CACHE
3127 * set. Note that B_CACHE is set according to the
3128 * byte-granular range ( bcount and size ), not the
3129 * aligned range ( newbsize ).
3131 * The VM test is against m->valid, which is DEV_BSIZE
3132 * aligned. Needless to say, the validity of the data
3133 * needs to also be DEV_BSIZE aligned. Note that this
3134 * fails with NFS if the server or some other client
3135 * extends the file's EOF. If our buffer is resized,
3136 * B_CACHE may remain set! XXX
3138 toff = bp->b_bcount;
3139 tinc = PAGE_SIZE - ((bp->b_offset + toff) & PAGE_MASK);
3140 while ((bp->b_flags & B_CACHE) && toff < size) {
3143 if (tinc > (size - toff))
3145 pi = ((bp->b_offset & PAGE_MASK) + toff) >> PAGE_SHIFT;
3146 m = bp->b_pages[pi];
3147 vfs_buf_test_cache(bp, bp->b_offset, toff, tinc, m);
3153 * Step 3, fixup the KVA pmap.
3158 BUF_CHECK_UNMAPPED(bp);
3162 * Check to see if a block at a particular lbn is available for a clustered
3166 vfs_bio_clcheck(struct vnode *vp, int size, daddr_t lblkno, daddr_t blkno)
3173 /* If the buf isn't in core skip it */
3174 if ((bpa = gbincore(&vp->v_bufobj, lblkno)) == NULL)
3177 /* If the buf is busy we don't want to wait for it */
3178 if (BUF_LOCK(bpa, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0)
3181 /* Only cluster with valid clusterable delayed write buffers */
3182 if ((bpa->b_flags & (B_DELWRI | B_CLUSTEROK | B_INVAL)) !=
3183 (B_DELWRI | B_CLUSTEROK))
3186 if (bpa->b_bufsize != size)
3190 * Check to see if it is in the expected place on disk and that the
3191 * block has been mapped.
3193 if ((bpa->b_blkno != bpa->b_lblkno) && (bpa->b_blkno == blkno))
3203 * Implement clustered async writes for clearing out B_DELWRI buffers.
3204 * This is much better then the old way of writing only one buffer at
3205 * a time. Note that we may not be presented with the buffers in the
3206 * correct order, so we search for the cluster in both directions.
3209 vfs_bio_awrite(struct buf *bp)
3214 daddr_t lblkno = bp->b_lblkno;
3215 struct vnode *vp = bp->b_vp;
3223 gbflags = (bp->b_data == unmapped_buf) ? GB_UNMAPPED : 0;
3225 * right now we support clustered writing only to regular files. If
3226 * we find a clusterable block we could be in the middle of a cluster
3227 * rather then at the beginning.
3229 if ((vp->v_type == VREG) &&
3230 (vp->v_mount != 0) && /* Only on nodes that have the size info */
3231 (bp->b_flags & (B_CLUSTEROK | B_INVAL)) == B_CLUSTEROK) {
3232 size = vp->v_mount->mnt_stat.f_iosize;
3233 maxcl = maxphys / size;
3236 for (i = 1; i < maxcl; i++)
3237 if (vfs_bio_clcheck(vp, size, lblkno + i,
3238 bp->b_blkno + ((i * size) >> DEV_BSHIFT)) == 0)
3241 for (j = 1; i + j <= maxcl && j <= lblkno; j++)
3242 if (vfs_bio_clcheck(vp, size, lblkno - j,
3243 bp->b_blkno - ((j * size) >> DEV_BSHIFT)) == 0)
3249 * this is a possible cluster write
3253 nwritten = cluster_wbuild(vp, size, lblkno - j, ncl,
3259 bp->b_flags |= B_ASYNC;
3261 * default (old) behavior, writing out only one block
3263 * XXX returns b_bufsize instead of b_bcount for nwritten?
3265 nwritten = bp->b_bufsize;
3274 * Allocate KVA for an empty buf header according to gbflags.
3277 getnewbuf_kva(struct buf *bp, int gbflags, int maxsize)
3280 if ((gbflags & (GB_UNMAPPED | GB_KVAALLOC)) != GB_UNMAPPED) {
3282 * In order to keep fragmentation sane we only allocate kva
3283 * in BKVASIZE chunks. XXX with vmem we can do page size.
3285 maxsize = (maxsize + BKVAMASK) & ~BKVAMASK;
3287 if (maxsize != bp->b_kvasize &&
3288 bufkva_alloc(bp, maxsize, gbflags))
3297 * Find and initialize a new buffer header, freeing up existing buffers
3298 * in the bufqueues as necessary. The new buffer is returned locked.
3301 * We have insufficient buffer headers
3302 * We have insufficient buffer space
3303 * buffer_arena is too fragmented ( space reservation fails )
3304 * If we have to flush dirty buffers ( but we try to avoid this )
3306 * The caller is responsible for releasing the reserved bufspace after
3307 * allocbuf() is called.
3310 getnewbuf(struct vnode *vp, int slpflag, int slptimeo, int maxsize, int gbflags)
3312 struct bufdomain *bd;
3314 bool metadata, reserved;
3317 KASSERT((gbflags & (GB_UNMAPPED | GB_KVAALLOC)) != GB_KVAALLOC,
3318 ("GB_KVAALLOC only makes sense with GB_UNMAPPED"));
3319 if (!unmapped_buf_allowed)
3320 gbflags &= ~(GB_UNMAPPED | GB_KVAALLOC);
3322 if (vp == NULL || (vp->v_vflag & (VV_MD | VV_SYSTEM)) != 0 ||
3330 bd = &bdomain[vp->v_bufobj.bo_domain];
3332 counter_u64_add(getnewbufcalls, 1);
3335 if (reserved == false &&
3336 bufspace_reserve(bd, maxsize, metadata) != 0) {
3337 counter_u64_add(getnewbufrestarts, 1);
3341 if ((bp = buf_alloc(bd)) == NULL) {
3342 counter_u64_add(getnewbufrestarts, 1);
3345 if (getnewbuf_kva(bp, gbflags, maxsize) == 0)
3348 } while (buf_recycle(bd, false) == 0);
3351 bufspace_release(bd, maxsize);
3353 bp->b_flags |= B_INVAL;
3356 bufspace_wait(bd, vp, gbflags, slpflag, slptimeo);
3364 * buffer flushing daemon. Buffers are normally flushed by the
3365 * update daemon but if it cannot keep up this process starts to
3366 * take the load in an attempt to prevent getnewbuf() from blocking.
3368 static struct kproc_desc buf_kp = {
3373 SYSINIT(bufdaemon, SI_SUB_KTHREAD_BUF, SI_ORDER_FIRST, kproc_start, &buf_kp);
3376 buf_flush(struct vnode *vp, struct bufdomain *bd, int target)
3380 flushed = flushbufqueues(vp, bd, target, 0);
3383 * Could not find any buffers without rollback
3384 * dependencies, so just write the first one
3385 * in the hopes of eventually making progress.
3387 if (vp != NULL && target > 2)
3389 flushbufqueues(vp, bd, target, 1);
3397 struct bufdomain *bd;
3403 * This process needs to be suspended prior to shutdown sync.
3405 EVENTHANDLER_REGISTER(shutdown_pre_sync, kthread_shutdown, curthread,
3406 SHUTDOWN_PRI_LAST + 100);
3409 * Start the buf clean daemons as children threads.
3411 for (i = 0 ; i < buf_domains; i++) {
3414 error = kthread_add((void (*)(void *))bufspace_daemon,
3415 &bdomain[i], curproc, NULL, 0, 0, "bufspacedaemon-%d", i);
3417 panic("error %d spawning bufspace daemon", error);
3421 * This process is allowed to take the buffer cache to the limit
3423 curthread->td_pflags |= TDP_NORUNNINGBUF | TDP_BUFNEED;
3427 mtx_unlock(&bdlock);
3429 kthread_suspend_check();
3432 * Save speedupreq for this pass and reset to capture new
3435 speedupreq = bd_speedupreq;
3439 * Flush each domain sequentially according to its level and
3440 * the speedup request.
3442 for (i = 0; i < buf_domains; i++) {
3445 lodirty = bd->bd_numdirtybuffers / 2;
3447 lodirty = bd->bd_lodirtybuffers;
3448 while (bd->bd_numdirtybuffers > lodirty) {
3449 if (buf_flush(NULL, bd,
3450 bd->bd_numdirtybuffers - lodirty) == 0)
3452 kern_yield(PRI_USER);
3457 * Only clear bd_request if we have reached our low water
3458 * mark. The buf_daemon normally waits 1 second and
3459 * then incrementally flushes any dirty buffers that have
3460 * built up, within reason.
3462 * If we were unable to hit our low water mark and couldn't
3463 * find any flushable buffers, we sleep for a short period
3464 * to avoid endless loops on unlockable buffers.
3467 if (!BIT_EMPTY(BUF_DOMAINS, &bdlodirty)) {
3469 * We reached our low water mark, reset the
3470 * request and sleep until we are needed again.
3471 * The sleep is just so the suspend code works.
3475 * Do an extra wakeup in case dirty threshold
3476 * changed via sysctl and the explicit transition
3477 * out of shortfall was missed.
3480 if (runningbufspace <= lorunningspace)
3482 msleep(&bd_request, &bdlock, PVM, "psleep", hz);
3485 * We couldn't find any flushable dirty buffers but
3486 * still have too many dirty buffers, we
3487 * have to sleep and try again. (rare)
3489 msleep(&bd_request, &bdlock, PVM, "qsleep", hz / 10);
3497 * Try to flush a buffer in the dirty queue. We must be careful to
3498 * free up B_INVAL buffers instead of write them, which NFS is
3499 * particularly sensitive to.
3501 static int flushwithdeps = 0;
3502 SYSCTL_INT(_vfs, OID_AUTO, flushwithdeps, CTLFLAG_RW | CTLFLAG_STATS,
3504 "Number of buffers flushed with dependencies that require rollbacks");
3507 flushbufqueues(struct vnode *lvp, struct bufdomain *bd, int target,
3510 struct bufqueue *bq;
3511 struct buf *sentinel;
3521 bq = &bd->bd_dirtyq;
3523 sentinel = malloc(sizeof(struct buf), M_TEMP, M_WAITOK | M_ZERO);
3524 sentinel->b_qindex = QUEUE_SENTINEL;
3526 TAILQ_INSERT_HEAD(&bq->bq_queue, sentinel, b_freelist);
3528 while (flushed != target) {
3531 bp = TAILQ_NEXT(sentinel, b_freelist);
3533 TAILQ_REMOVE(&bq->bq_queue, sentinel, b_freelist);
3534 TAILQ_INSERT_AFTER(&bq->bq_queue, bp, sentinel,
3541 * Skip sentinels inserted by other invocations of the
3542 * flushbufqueues(), taking care to not reorder them.
3544 * Only flush the buffers that belong to the
3545 * vnode locked by the curthread.
3547 if (bp->b_qindex == QUEUE_SENTINEL || (lvp != NULL &&
3552 error = BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL);
3558 * BKGRDINPROG can only be set with the buf and bufobj
3559 * locks both held. We tolerate a race to clear it here.
3561 if ((bp->b_vflags & BV_BKGRDINPROG) != 0 ||
3562 (bp->b_flags & B_DELWRI) == 0) {
3566 if (bp->b_flags & B_INVAL) {
3573 if (!LIST_EMPTY(&bp->b_dep) && buf_countdeps(bp, 0)) {
3574 if (flushdeps == 0) {
3582 * We must hold the lock on a vnode before writing
3583 * one of its buffers. Otherwise we may confuse, or
3584 * in the case of a snapshot vnode, deadlock the
3587 * The lock order here is the reverse of the normal
3588 * of vnode followed by buf lock. This is ok because
3589 * the NOWAIT will prevent deadlock.
3592 if (vn_start_write(vp, &mp, V_NOWAIT) != 0) {
3598 error = vn_lock(vp, LK_EXCLUSIVE | LK_NOWAIT);
3600 ASSERT_VOP_LOCKED(vp, "getbuf");
3602 error = VOP_ISLOCKED(vp) == LK_EXCLUSIVE ? 0 :
3603 vn_lock(vp, LK_TRYUPGRADE);
3606 CTR3(KTR_BUF, "flushbufqueue(%p) vp %p flags %X",
3607 bp, bp->b_vp, bp->b_flags);
3608 if (curproc == bufdaemonproc) {
3613 counter_u64_add(notbufdflushes, 1);
3615 vn_finished_write(mp);
3618 flushwithdeps += hasdeps;
3622 * Sleeping on runningbufspace while holding
3623 * vnode lock leads to deadlock.
3625 if (curproc == bufdaemonproc &&
3626 runningbufspace > hirunningspace)
3627 waitrunningbufspace();
3630 vn_finished_write(mp);
3634 TAILQ_REMOVE(&bq->bq_queue, sentinel, b_freelist);
3636 free(sentinel, M_TEMP);
3641 * Check to see if a block is currently memory resident.
3644 incore(struct bufobj *bo, daddr_t blkno)
3646 return (gbincore_unlocked(bo, blkno));
3650 * Returns true if no I/O is needed to access the
3651 * associated VM object. This is like incore except
3652 * it also hunts around in the VM system for the data.
3655 inmem(struct vnode * vp, daddr_t blkno)
3658 vm_offset_t toff, tinc, size;
3663 ASSERT_VOP_LOCKED(vp, "inmem");
3665 if (incore(&vp->v_bufobj, blkno))
3667 if (vp->v_mount == NULL)
3674 if (size > vp->v_mount->mnt_stat.f_iosize)
3675 size = vp->v_mount->mnt_stat.f_iosize;
3676 off = (vm_ooffset_t)blkno * (vm_ooffset_t)vp->v_mount->mnt_stat.f_iosize;
3678 for (toff = 0; toff < vp->v_mount->mnt_stat.f_iosize; toff += tinc) {
3679 m = vm_page_lookup_unlocked(obj, OFF_TO_IDX(off + toff));
3685 if (tinc > PAGE_SIZE - ((toff + off) & PAGE_MASK))
3686 tinc = PAGE_SIZE - ((toff + off) & PAGE_MASK);
3688 * Consider page validity only if page mapping didn't change
3691 valid = vm_page_is_valid(m,
3692 (vm_offset_t)((toff + off) & PAGE_MASK), tinc);
3693 n = vm_page_lookup_unlocked(obj, OFF_TO_IDX(off + toff));
3705 * Set the dirty range for a buffer based on the status of the dirty
3706 * bits in the pages comprising the buffer. The range is limited
3707 * to the size of the buffer.
3709 * Tell the VM system that the pages associated with this buffer
3710 * are clean. This is used for delayed writes where the data is
3711 * going to go to disk eventually without additional VM intevention.
3713 * Note that while we only really need to clean through to b_bcount, we
3714 * just go ahead and clean through to b_bufsize.
3717 vfs_clean_pages_dirty_buf(struct buf *bp)
3719 vm_ooffset_t foff, noff, eoff;
3723 if ((bp->b_flags & B_VMIO) == 0 || bp->b_bufsize == 0)
3726 foff = bp->b_offset;
3727 KASSERT(bp->b_offset != NOOFFSET,
3728 ("vfs_clean_pages_dirty_buf: no buffer offset"));
3730 vfs_busy_pages_acquire(bp);
3731 vfs_setdirty_range(bp);
3732 for (i = 0; i < bp->b_npages; i++) {
3733 noff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK;
3735 if (eoff > bp->b_offset + bp->b_bufsize)
3736 eoff = bp->b_offset + bp->b_bufsize;
3738 vfs_page_set_validclean(bp, foff, m);
3739 /* vm_page_clear_dirty(m, foff & PAGE_MASK, eoff - foff); */
3742 vfs_busy_pages_release(bp);
3746 vfs_setdirty_range(struct buf *bp)
3748 vm_offset_t boffset;
3749 vm_offset_t eoffset;
3753 * test the pages to see if they have been modified directly
3754 * by users through the VM system.
3756 for (i = 0; i < bp->b_npages; i++)
3757 vm_page_test_dirty(bp->b_pages[i]);
3760 * Calculate the encompassing dirty range, boffset and eoffset,
3761 * (eoffset - boffset) bytes.
3764 for (i = 0; i < bp->b_npages; i++) {
3765 if (bp->b_pages[i]->dirty)
3768 boffset = (i << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK);
3770 for (i = bp->b_npages - 1; i >= 0; --i) {
3771 if (bp->b_pages[i]->dirty) {
3775 eoffset = ((i + 1) << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK);
3778 * Fit it to the buffer.
3781 if (eoffset > bp->b_bcount)
3782 eoffset = bp->b_bcount;
3785 * If we have a good dirty range, merge with the existing
3789 if (boffset < eoffset) {
3790 if (bp->b_dirtyoff > boffset)
3791 bp->b_dirtyoff = boffset;
3792 if (bp->b_dirtyend < eoffset)
3793 bp->b_dirtyend = eoffset;
3798 * Allocate the KVA mapping for an existing buffer.
3799 * If an unmapped buffer is provided but a mapped buffer is requested, take
3800 * also care to properly setup mappings between pages and KVA.
3803 bp_unmapped_get_kva(struct buf *bp, daddr_t blkno, int size, int gbflags)
3805 int bsize, maxsize, need_mapping, need_kva;
3808 need_mapping = bp->b_data == unmapped_buf &&
3809 (gbflags & GB_UNMAPPED) == 0;
3810 need_kva = bp->b_kvabase == unmapped_buf &&
3811 bp->b_data == unmapped_buf &&
3812 (gbflags & GB_KVAALLOC) != 0;
3813 if (!need_mapping && !need_kva)
3816 BUF_CHECK_UNMAPPED(bp);
3818 if (need_mapping && bp->b_kvabase != unmapped_buf) {
3820 * Buffer is not mapped, but the KVA was already
3821 * reserved at the time of the instantiation. Use the
3828 * Calculate the amount of the address space we would reserve
3829 * if the buffer was mapped.
3831 bsize = vn_isdisk(bp->b_vp) ? DEV_BSIZE : bp->b_bufobj->bo_bsize;
3832 KASSERT(bsize != 0, ("bsize == 0, check bo->bo_bsize"));
3833 offset = blkno * bsize;
3834 maxsize = size + (offset & PAGE_MASK);
3835 maxsize = imax(maxsize, bsize);
3837 while (bufkva_alloc(bp, maxsize, gbflags) != 0) {
3838 if ((gbflags & GB_NOWAIT_BD) != 0) {
3840 * XXXKIB: defragmentation cannot
3841 * succeed, not sure what else to do.
3843 panic("GB_NOWAIT_BD and GB_UNMAPPED %p", bp);
3845 counter_u64_add(mappingrestarts, 1);
3846 bufspace_wait(bufdomain(bp), bp->b_vp, gbflags, 0, 0);
3850 /* b_offset is handled by bpmap_qenter. */
3851 bp->b_data = bp->b_kvabase;
3852 BUF_CHECK_MAPPED(bp);
3858 getblk(struct vnode *vp, daddr_t blkno, int size, int slpflag, int slptimeo,
3864 error = getblkx(vp, blkno, blkno, size, slpflag, slptimeo, flags, &bp);
3873 * Get a block given a specified block and offset into a file/device.
3874 * The buffers B_DONE bit will be cleared on return, making it almost
3875 * ready for an I/O initiation. B_INVAL may or may not be set on
3876 * return. The caller should clear B_INVAL prior to initiating a
3879 * For a non-VMIO buffer, B_CACHE is set to the opposite of B_INVAL for
3880 * an existing buffer.
3882 * For a VMIO buffer, B_CACHE is modified according to the backing VM.
3883 * If getblk()ing a previously 0-sized invalid buffer, B_CACHE is set
3884 * and then cleared based on the backing VM. If the previous buffer is
3885 * non-0-sized but invalid, B_CACHE will be cleared.
3887 * If getblk() must create a new buffer, the new buffer is returned with
3888 * both B_INVAL and B_CACHE clear unless it is a VMIO buffer, in which
3889 * case it is returned with B_INVAL clear and B_CACHE set based on the
3892 * getblk() also forces a bwrite() for any B_DELWRI buffer whose
3893 * B_CACHE bit is clear.
3895 * What this means, basically, is that the caller should use B_CACHE to
3896 * determine whether the buffer is fully valid or not and should clear
3897 * B_INVAL prior to issuing a read. If the caller intends to validate
3898 * the buffer by loading its data area with something, the caller needs
3899 * to clear B_INVAL. If the caller does this without issuing an I/O,
3900 * the caller should set B_CACHE ( as an optimization ), else the caller
3901 * should issue the I/O and biodone() will set B_CACHE if the I/O was
3902 * a write attempt or if it was a successful read. If the caller
3903 * intends to issue a READ, the caller must clear B_INVAL and BIO_ERROR
3904 * prior to issuing the READ. biodone() will *not* clear B_INVAL.
3906 * The blkno parameter is the logical block being requested. Normally
3907 * the mapping of logical block number to disk block address is done
3908 * by calling VOP_BMAP(). However, if the mapping is already known, the
3909 * disk block address can be passed using the dblkno parameter. If the
3910 * disk block address is not known, then the same value should be passed
3911 * for blkno and dblkno.
3914 getblkx(struct vnode *vp, daddr_t blkno, daddr_t dblkno, int size, int slpflag,
3915 int slptimeo, int flags, struct buf **bpp)
3920 int bsize, error, maxsize, vmio;
3923 CTR3(KTR_BUF, "getblk(%p, %ld, %d)", vp, (long)blkno, size);
3924 KASSERT((flags & (GB_UNMAPPED | GB_KVAALLOC)) != GB_KVAALLOC,
3925 ("GB_KVAALLOC only makes sense with GB_UNMAPPED"));
3926 if (vp->v_type != VCHR)
3927 ASSERT_VOP_LOCKED(vp, "getblk");
3928 if (size > maxbcachebuf)
3929 panic("getblk: size(%d) > maxbcachebuf(%d)\n", size,
3931 if (!unmapped_buf_allowed)
3932 flags &= ~(GB_UNMAPPED | GB_KVAALLOC);
3937 /* Attempt lockless lookup first. */
3938 bp = gbincore_unlocked(bo, blkno);
3941 * With GB_NOCREAT we must be sure about not finding the buffer
3942 * as it may have been reassigned during unlocked lookup.
3944 if ((flags & GB_NOCREAT) != 0)
3946 goto newbuf_unlocked;
3949 error = BUF_TIMELOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL, "getblku", 0,
3954 /* Verify buf identify has not changed since lookup. */
3955 if (bp->b_bufobj == bo && bp->b_lblkno == blkno)
3956 goto foundbuf_fastpath;
3958 /* It changed, fallback to locked lookup. */
3963 bp = gbincore(bo, blkno);
3968 * Buffer is in-core. If the buffer is not busy nor managed,
3969 * it must be on a queue.
3971 lockflags = LK_EXCLUSIVE | LK_INTERLOCK |
3972 ((flags & GB_LOCK_NOWAIT) ? LK_NOWAIT : LK_SLEEPFAIL);
3974 error = BUF_TIMELOCK(bp, lockflags,
3975 BO_LOCKPTR(bo), "getblk", slpflag, slptimeo);
3978 * If we slept and got the lock we have to restart in case
3979 * the buffer changed identities.
3981 if (error == ENOLCK)
3983 /* We timed out or were interrupted. */
3984 else if (error != 0)
3988 /* If recursed, assume caller knows the rules. */
3989 if (BUF_LOCKRECURSED(bp))
3993 * The buffer is locked. B_CACHE is cleared if the buffer is
3994 * invalid. Otherwise, for a non-VMIO buffer, B_CACHE is set
3995 * and for a VMIO buffer B_CACHE is adjusted according to the
3998 if (bp->b_flags & B_INVAL)
3999 bp->b_flags &= ~B_CACHE;
4000 else if ((bp->b_flags & (B_VMIO | B_INVAL)) == 0)
4001 bp->b_flags |= B_CACHE;
4002 if (bp->b_flags & B_MANAGED)
4003 MPASS(bp->b_qindex == QUEUE_NONE);
4008 * check for size inconsistencies for non-VMIO case.
4010 if (bp->b_bcount != size) {
4011 if ((bp->b_flags & B_VMIO) == 0 ||
4012 (size > bp->b_kvasize)) {
4013 if (bp->b_flags & B_DELWRI) {
4014 bp->b_flags |= B_NOCACHE;
4017 if (LIST_EMPTY(&bp->b_dep)) {
4018 bp->b_flags |= B_RELBUF;
4021 bp->b_flags |= B_NOCACHE;
4030 * Handle the case of unmapped buffer which should
4031 * become mapped, or the buffer for which KVA
4032 * reservation is requested.
4034 bp_unmapped_get_kva(bp, blkno, size, flags);
4037 * If the size is inconsistent in the VMIO case, we can resize
4038 * the buffer. This might lead to B_CACHE getting set or
4039 * cleared. If the size has not changed, B_CACHE remains
4040 * unchanged from its previous state.
4044 KASSERT(bp->b_offset != NOOFFSET,
4045 ("getblk: no buffer offset"));
4048 * A buffer with B_DELWRI set and B_CACHE clear must
4049 * be committed before we can return the buffer in
4050 * order to prevent the caller from issuing a read
4051 * ( due to B_CACHE not being set ) and overwriting
4054 * Most callers, including NFS and FFS, need this to
4055 * operate properly either because they assume they
4056 * can issue a read if B_CACHE is not set, or because
4057 * ( for example ) an uncached B_DELWRI might loop due
4058 * to softupdates re-dirtying the buffer. In the latter
4059 * case, B_CACHE is set after the first write completes,
4060 * preventing further loops.
4061 * NOTE! b*write() sets B_CACHE. If we cleared B_CACHE
4062 * above while extending the buffer, we cannot allow the
4063 * buffer to remain with B_CACHE set after the write
4064 * completes or it will represent a corrupt state. To
4065 * deal with this we set B_NOCACHE to scrap the buffer
4068 * We might be able to do something fancy, like setting
4069 * B_CACHE in bwrite() except if B_DELWRI is already set,
4070 * so the below call doesn't set B_CACHE, but that gets real
4071 * confusing. This is much easier.
4074 if ((bp->b_flags & (B_CACHE|B_DELWRI)) == B_DELWRI) {
4075 bp->b_flags |= B_NOCACHE;
4079 bp->b_flags &= ~B_DONE;
4082 * Buffer is not in-core, create new buffer. The buffer
4083 * returned by getnewbuf() is locked. Note that the returned
4084 * buffer is also considered valid (not marked B_INVAL).
4089 * If the user does not want us to create the buffer, bail out
4092 if (flags & GB_NOCREAT)
4095 bsize = vn_isdisk(vp) ? DEV_BSIZE : bo->bo_bsize;
4096 KASSERT(bsize != 0, ("bsize == 0, check bo->bo_bsize"));
4097 offset = blkno * bsize;
4098 vmio = vp->v_object != NULL;
4100 maxsize = size + (offset & PAGE_MASK);
4103 /* Do not allow non-VMIO notmapped buffers. */
4104 flags &= ~(GB_UNMAPPED | GB_KVAALLOC);
4106 maxsize = imax(maxsize, bsize);
4107 if ((flags & GB_NOSPARSE) != 0 && vmio &&
4109 error = VOP_BMAP(vp, blkno, NULL, &d_blkno, 0, 0);
4110 KASSERT(error != EOPNOTSUPP,
4111 ("GB_NOSPARSE from fs not supporting bmap, vp %p",
4116 return (EJUSTRETURN);
4119 bp = getnewbuf(vp, slpflag, slptimeo, maxsize, flags);
4121 if (slpflag || slptimeo)
4124 * XXX This is here until the sleep path is diagnosed
4125 * enough to work under very low memory conditions.
4127 * There's an issue on low memory, 4BSD+non-preempt
4128 * systems (eg MIPS routers with 32MB RAM) where buffer
4129 * exhaustion occurs without sleeping for buffer
4130 * reclaimation. This just sticks in a loop and
4131 * constantly attempts to allocate a buffer, which
4132 * hits exhaustion and tries to wakeup bufdaemon.
4133 * This never happens because we never yield.
4135 * The real solution is to identify and fix these cases
4136 * so we aren't effectively busy-waiting in a loop
4137 * until the reclaimation path has cycles to run.
4139 kern_yield(PRI_USER);
4144 * This code is used to make sure that a buffer is not
4145 * created while the getnewbuf routine is blocked.
4146 * This can be a problem whether the vnode is locked or not.
4147 * If the buffer is created out from under us, we have to
4148 * throw away the one we just created.
4150 * Note: this must occur before we associate the buffer
4151 * with the vp especially considering limitations in
4152 * the splay tree implementation when dealing with duplicate
4156 if (gbincore(bo, blkno)) {
4158 bp->b_flags |= B_INVAL;
4159 bufspace_release(bufdomain(bp), maxsize);
4165 * Insert the buffer into the hash, so that it can
4166 * be found by incore.
4168 bp->b_lblkno = blkno;
4169 bp->b_blkno = d_blkno;
4170 bp->b_offset = offset;
4175 * set B_VMIO bit. allocbuf() the buffer bigger. Since the
4176 * buffer size starts out as 0, B_CACHE will be set by
4177 * allocbuf() for the VMIO case prior to it testing the
4178 * backing store for validity.
4182 bp->b_flags |= B_VMIO;
4183 KASSERT(vp->v_object == bp->b_bufobj->bo_object,
4184 ("ARGH! different b_bufobj->bo_object %p %p %p\n",
4185 bp, vp->v_object, bp->b_bufobj->bo_object));
4187 bp->b_flags &= ~B_VMIO;
4188 KASSERT(bp->b_bufobj->bo_object == NULL,
4189 ("ARGH! has b_bufobj->bo_object %p %p\n",
4190 bp, bp->b_bufobj->bo_object));
4191 BUF_CHECK_MAPPED(bp);
4195 bufspace_release(bufdomain(bp), maxsize);
4196 bp->b_flags &= ~B_DONE;
4198 CTR4(KTR_BUF, "getblk(%p, %ld, %d) = %p", vp, (long)blkno, size, bp);
4200 buf_track(bp, __func__);
4201 KASSERT(bp->b_bufobj == bo,
4202 ("bp %p wrong b_bufobj %p should be %p", bp, bp->b_bufobj, bo));
4208 * Get an empty, disassociated buffer of given size. The buffer is initially
4212 geteblk(int size, int flags)
4217 maxsize = (size + BKVAMASK) & ~BKVAMASK;
4218 while ((bp = getnewbuf(NULL, 0, 0, maxsize, flags)) == NULL) {
4219 if ((flags & GB_NOWAIT_BD) &&
4220 (curthread->td_pflags & TDP_BUFNEED) != 0)
4224 bufspace_release(bufdomain(bp), maxsize);
4225 bp->b_flags |= B_INVAL; /* b_dep cleared by getnewbuf() */
4230 * Truncate the backing store for a non-vmio buffer.
4233 vfs_nonvmio_truncate(struct buf *bp, int newbsize)
4236 if (bp->b_flags & B_MALLOC) {
4238 * malloced buffers are not shrunk
4240 if (newbsize == 0) {
4241 bufmallocadjust(bp, 0);
4242 free(bp->b_data, M_BIOBUF);
4243 bp->b_data = bp->b_kvabase;
4244 bp->b_flags &= ~B_MALLOC;
4248 vm_hold_free_pages(bp, newbsize);
4249 bufspace_adjust(bp, newbsize);
4253 * Extend the backing for a non-VMIO buffer.
4256 vfs_nonvmio_extend(struct buf *bp, int newbsize)
4262 * We only use malloced memory on the first allocation.
4263 * and revert to page-allocated memory when the buffer
4266 * There is a potential smp race here that could lead
4267 * to bufmallocspace slightly passing the max. It
4268 * is probably extremely rare and not worth worrying
4271 if (bp->b_bufsize == 0 && newbsize <= PAGE_SIZE/2 &&
4272 bufmallocspace < maxbufmallocspace) {
4273 bp->b_data = malloc(newbsize, M_BIOBUF, M_WAITOK);
4274 bp->b_flags |= B_MALLOC;
4275 bufmallocadjust(bp, newbsize);
4280 * If the buffer is growing on its other-than-first
4281 * allocation then we revert to the page-allocation
4286 if (bp->b_flags & B_MALLOC) {
4287 origbuf = bp->b_data;
4288 origbufsize = bp->b_bufsize;
4289 bp->b_data = bp->b_kvabase;
4290 bufmallocadjust(bp, 0);
4291 bp->b_flags &= ~B_MALLOC;
4292 newbsize = round_page(newbsize);
4294 vm_hold_load_pages(bp, (vm_offset_t) bp->b_data + bp->b_bufsize,
4295 (vm_offset_t) bp->b_data + newbsize);
4296 if (origbuf != NULL) {
4297 bcopy(origbuf, bp->b_data, origbufsize);
4298 free(origbuf, M_BIOBUF);
4300 bufspace_adjust(bp, newbsize);
4304 * This code constitutes the buffer memory from either anonymous system
4305 * memory (in the case of non-VMIO operations) or from an associated
4306 * VM object (in the case of VMIO operations). This code is able to
4307 * resize a buffer up or down.
4309 * Note that this code is tricky, and has many complications to resolve
4310 * deadlock or inconsistent data situations. Tread lightly!!!
4311 * There are B_CACHE and B_DELWRI interactions that must be dealt with by
4312 * the caller. Calling this code willy nilly can result in the loss of data.
4314 * allocbuf() only adjusts B_CACHE for VMIO buffers. getblk() deals with
4315 * B_CACHE for the non-VMIO case.
4318 allocbuf(struct buf *bp, int size)
4322 if (bp->b_bcount == size)
4325 if (bp->b_kvasize != 0 && bp->b_kvasize < size)
4326 panic("allocbuf: buffer too small");
4328 newbsize = roundup2(size, DEV_BSIZE);
4329 if ((bp->b_flags & B_VMIO) == 0) {
4330 if ((bp->b_flags & B_MALLOC) == 0)
4331 newbsize = round_page(newbsize);
4333 * Just get anonymous memory from the kernel. Don't
4334 * mess with B_CACHE.
4336 if (newbsize < bp->b_bufsize)
4337 vfs_nonvmio_truncate(bp, newbsize);
4338 else if (newbsize > bp->b_bufsize)
4339 vfs_nonvmio_extend(bp, newbsize);
4343 desiredpages = (size == 0) ? 0 :
4344 num_pages((bp->b_offset & PAGE_MASK) + newbsize);
4346 if (bp->b_flags & B_MALLOC)
4347 panic("allocbuf: VMIO buffer can't be malloced");
4349 * Set B_CACHE initially if buffer is 0 length or will become
4352 if (size == 0 || bp->b_bufsize == 0)
4353 bp->b_flags |= B_CACHE;
4355 if (newbsize < bp->b_bufsize)
4356 vfs_vmio_truncate(bp, desiredpages);
4357 /* XXX This looks as if it should be newbsize > b_bufsize */
4358 else if (size > bp->b_bcount)
4359 vfs_vmio_extend(bp, desiredpages, size);
4360 bufspace_adjust(bp, newbsize);
4362 bp->b_bcount = size; /* requested buffer size. */
4366 extern int inflight_transient_maps;
4368 static struct bio_queue nondump_bios;
4371 biodone(struct bio *bp)
4374 void (*done)(struct bio *);
4375 vm_offset_t start, end;
4377 biotrack(bp, __func__);
4380 * Avoid completing I/O when dumping after a panic since that may
4381 * result in a deadlock in the filesystem or pager code. Note that
4382 * this doesn't affect dumps that were started manually since we aim
4383 * to keep the system usable after it has been resumed.
4385 if (__predict_false(dumping && SCHEDULER_STOPPED())) {
4386 TAILQ_INSERT_HEAD(&nondump_bios, bp, bio_queue);
4389 if ((bp->bio_flags & BIO_TRANSIENT_MAPPING) != 0) {
4390 bp->bio_flags &= ~BIO_TRANSIENT_MAPPING;
4391 bp->bio_flags |= BIO_UNMAPPED;
4392 start = trunc_page((vm_offset_t)bp->bio_data);
4393 end = round_page((vm_offset_t)bp->bio_data + bp->bio_length);
4394 bp->bio_data = unmapped_buf;
4395 pmap_qremove(start, atop(end - start));
4396 vmem_free(transient_arena, start, end - start);
4397 atomic_add_int(&inflight_transient_maps, -1);
4399 done = bp->bio_done;
4401 * The check for done == biodone is to allow biodone to be
4402 * used as a bio_done routine.
4404 if (done == NULL || done == biodone) {
4405 mtxp = mtx_pool_find(mtxpool_sleep, bp);
4407 bp->bio_flags |= BIO_DONE;
4415 * Wait for a BIO to finish.
4418 biowait(struct bio *bp, const char *wmesg)
4422 mtxp = mtx_pool_find(mtxpool_sleep, bp);
4424 while ((bp->bio_flags & BIO_DONE) == 0)
4425 msleep(bp, mtxp, PRIBIO, wmesg, 0);
4427 if (bp->bio_error != 0)
4428 return (bp->bio_error);
4429 if (!(bp->bio_flags & BIO_ERROR))
4435 biofinish(struct bio *bp, struct devstat *stat, int error)
4439 bp->bio_error = error;
4440 bp->bio_flags |= BIO_ERROR;
4443 devstat_end_transaction_bio(stat, bp);
4447 #if defined(BUF_TRACKING) || defined(FULL_BUF_TRACKING)
4449 biotrack_buf(struct bio *bp, const char *location)
4452 buf_track(bp->bio_track_bp, location);
4459 * Wait for buffer I/O completion, returning error status. The buffer
4460 * is left locked and B_DONE on return. B_EINTR is converted into an EINTR
4461 * error and cleared.
4464 bufwait(struct buf *bp)
4466 if (bp->b_iocmd == BIO_READ)
4467 bwait(bp, PRIBIO, "biord");
4469 bwait(bp, PRIBIO, "biowr");
4470 if (bp->b_flags & B_EINTR) {
4471 bp->b_flags &= ~B_EINTR;
4474 if (bp->b_ioflags & BIO_ERROR) {
4475 return (bp->b_error ? bp->b_error : EIO);
4484 * Finish I/O on a buffer, optionally calling a completion function.
4485 * This is usually called from an interrupt so process blocking is
4488 * biodone is also responsible for setting B_CACHE in a B_VMIO bp.
4489 * In a non-VMIO bp, B_CACHE will be set on the next getblk()
4490 * assuming B_INVAL is clear.
4492 * For the VMIO case, we set B_CACHE if the op was a read and no
4493 * read error occurred, or if the op was a write. B_CACHE is never
4494 * set if the buffer is invalid or otherwise uncacheable.
4496 * bufdone does not mess with B_INVAL, allowing the I/O routine or the
4497 * initiator to leave B_INVAL set to brelse the buffer out of existence
4498 * in the biodone routine.
4501 bufdone(struct buf *bp)
4503 struct bufobj *dropobj;
4504 void (*biodone)(struct buf *);
4506 buf_track(bp, __func__);
4507 CTR3(KTR_BUF, "bufdone(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
4510 KASSERT(!(bp->b_flags & B_DONE), ("biodone: bp %p already done", bp));
4512 runningbufwakeup(bp);
4513 if (bp->b_iocmd == BIO_WRITE)
4514 dropobj = bp->b_bufobj;
4515 /* call optional completion function if requested */
4516 if (bp->b_iodone != NULL) {
4517 biodone = bp->b_iodone;
4518 bp->b_iodone = NULL;
4521 bufobj_wdrop(dropobj);
4524 if (bp->b_flags & B_VMIO) {
4526 * Set B_CACHE if the op was a normal read and no error
4527 * occurred. B_CACHE is set for writes in the b*write()
4530 if (bp->b_iocmd == BIO_READ &&
4531 !(bp->b_flags & (B_INVAL|B_NOCACHE)) &&
4532 !(bp->b_ioflags & BIO_ERROR))
4533 bp->b_flags |= B_CACHE;
4534 vfs_vmio_iodone(bp);
4536 if (!LIST_EMPTY(&bp->b_dep))
4538 if ((bp->b_flags & B_CKHASH) != 0) {
4539 KASSERT(bp->b_iocmd == BIO_READ,
4540 ("bufdone: b_iocmd %d not BIO_READ", bp->b_iocmd));
4541 KASSERT(buf_mapped(bp), ("bufdone: bp %p not mapped", bp));
4542 (*bp->b_ckhashcalc)(bp);
4545 * For asynchronous completions, release the buffer now. The brelse
4546 * will do a wakeup there if necessary - so no need to do a wakeup
4547 * here in the async case. The sync case always needs to do a wakeup.
4549 if (bp->b_flags & B_ASYNC) {
4550 if ((bp->b_flags & (B_NOCACHE | B_INVAL | B_RELBUF)) ||
4551 (bp->b_ioflags & BIO_ERROR))
4558 bufobj_wdrop(dropobj);
4562 * This routine is called in lieu of iodone in the case of
4563 * incomplete I/O. This keeps the busy status for pages
4567 vfs_unbusy_pages(struct buf *bp)
4573 runningbufwakeup(bp);
4574 if (!(bp->b_flags & B_VMIO))
4577 obj = bp->b_bufobj->bo_object;
4578 for (i = 0; i < bp->b_npages; i++) {
4580 if (m == bogus_page) {
4581 m = vm_page_relookup(obj, OFF_TO_IDX(bp->b_offset) + i);
4583 panic("vfs_unbusy_pages: page missing\n");
4585 if (buf_mapped(bp)) {
4586 BUF_CHECK_MAPPED(bp);
4587 pmap_qenter(trunc_page((vm_offset_t)bp->b_data),
4588 bp->b_pages, bp->b_npages);
4590 BUF_CHECK_UNMAPPED(bp);
4594 vm_object_pip_wakeupn(obj, bp->b_npages);
4598 * vfs_page_set_valid:
4600 * Set the valid bits in a page based on the supplied offset. The
4601 * range is restricted to the buffer's size.
4603 * This routine is typically called after a read completes.
4606 vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, vm_page_t m)
4611 * Compute the end offset, eoff, such that [off, eoff) does not span a
4612 * page boundary and eoff is not greater than the end of the buffer.
4613 * The end of the buffer, in this case, is our file EOF, not the
4614 * allocation size of the buffer.
4616 eoff = (off + PAGE_SIZE) & ~(vm_ooffset_t)PAGE_MASK;
4617 if (eoff > bp->b_offset + bp->b_bcount)
4618 eoff = bp->b_offset + bp->b_bcount;
4621 * Set valid range. This is typically the entire buffer and thus the
4625 vm_page_set_valid_range(m, off & PAGE_MASK, eoff - off);
4629 * vfs_page_set_validclean:
4631 * Set the valid bits and clear the dirty bits in a page based on the
4632 * supplied offset. The range is restricted to the buffer's size.
4635 vfs_page_set_validclean(struct buf *bp, vm_ooffset_t off, vm_page_t m)
4637 vm_ooffset_t soff, eoff;
4640 * Start and end offsets in buffer. eoff - soff may not cross a
4641 * page boundary or cross the end of the buffer. The end of the
4642 * buffer, in this case, is our file EOF, not the allocation size
4646 eoff = (off + PAGE_SIZE) & ~(off_t)PAGE_MASK;
4647 if (eoff > bp->b_offset + bp->b_bcount)
4648 eoff = bp->b_offset + bp->b_bcount;
4651 * Set valid range. This is typically the entire buffer and thus the
4655 vm_page_set_validclean(
4657 (vm_offset_t) (soff & PAGE_MASK),
4658 (vm_offset_t) (eoff - soff)
4664 * Acquire a shared busy on all pages in the buf.
4667 vfs_busy_pages_acquire(struct buf *bp)
4671 for (i = 0; i < bp->b_npages; i++)
4672 vm_page_busy_acquire(bp->b_pages[i], VM_ALLOC_SBUSY);
4676 vfs_busy_pages_release(struct buf *bp)
4680 for (i = 0; i < bp->b_npages; i++)
4681 vm_page_sunbusy(bp->b_pages[i]);
4685 * This routine is called before a device strategy routine.
4686 * It is used to tell the VM system that paging I/O is in
4687 * progress, and treat the pages associated with the buffer
4688 * almost as being exclusive busy. Also the object paging_in_progress
4689 * flag is handled to make sure that the object doesn't become
4692 * Since I/O has not been initiated yet, certain buffer flags
4693 * such as BIO_ERROR or B_INVAL may be in an inconsistent state
4694 * and should be ignored.
4697 vfs_busy_pages(struct buf *bp, int clear_modify)
4705 if (!(bp->b_flags & B_VMIO))
4708 obj = bp->b_bufobj->bo_object;
4709 foff = bp->b_offset;
4710 KASSERT(bp->b_offset != NOOFFSET,
4711 ("vfs_busy_pages: no buffer offset"));
4712 if ((bp->b_flags & B_CLUSTER) == 0) {
4713 vm_object_pip_add(obj, bp->b_npages);
4714 vfs_busy_pages_acquire(bp);
4716 if (bp->b_bufsize != 0)
4717 vfs_setdirty_range(bp);
4719 for (i = 0; i < bp->b_npages; i++) {
4721 vm_page_assert_sbusied(m);
4724 * When readying a buffer for a read ( i.e
4725 * clear_modify == 0 ), it is important to do
4726 * bogus_page replacement for valid pages in
4727 * partially instantiated buffers. Partially
4728 * instantiated buffers can, in turn, occur when
4729 * reconstituting a buffer from its VM backing store
4730 * base. We only have to do this if B_CACHE is
4731 * clear ( which causes the I/O to occur in the
4732 * first place ). The replacement prevents the read
4733 * I/O from overwriting potentially dirty VM-backed
4734 * pages. XXX bogus page replacement is, uh, bogus.
4735 * It may not work properly with small-block devices.
4736 * We need to find a better way.
4739 pmap_remove_write(m);
4740 vfs_page_set_validclean(bp, foff, m);
4741 } else if (vm_page_all_valid(m) &&
4742 (bp->b_flags & B_CACHE) == 0) {
4743 bp->b_pages[i] = bogus_page;
4746 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK;
4748 if (bogus && buf_mapped(bp)) {
4749 BUF_CHECK_MAPPED(bp);
4750 pmap_qenter(trunc_page((vm_offset_t)bp->b_data),
4751 bp->b_pages, bp->b_npages);
4756 * vfs_bio_set_valid:
4758 * Set the range within the buffer to valid. The range is
4759 * relative to the beginning of the buffer, b_offset. Note that
4760 * b_offset itself may be offset from the beginning of the first
4764 vfs_bio_set_valid(struct buf *bp, int base, int size)
4769 if (!(bp->b_flags & B_VMIO))
4773 * Fixup base to be relative to beginning of first page.
4774 * Set initial n to be the maximum number of bytes in the
4775 * first page that can be validated.
4777 base += (bp->b_offset & PAGE_MASK);
4778 n = PAGE_SIZE - (base & PAGE_MASK);
4781 * Busy may not be strictly necessary here because the pages are
4782 * unlikely to be fully valid and the vnode lock will synchronize
4783 * their access via getpages. It is grabbed for consistency with
4784 * other page validation.
4786 vfs_busy_pages_acquire(bp);
4787 for (i = base / PAGE_SIZE; size > 0 && i < bp->b_npages; ++i) {
4791 vm_page_set_valid_range(m, base & PAGE_MASK, n);
4796 vfs_busy_pages_release(bp);
4802 * If the specified buffer is a non-VMIO buffer, clear the entire
4803 * buffer. If the specified buffer is a VMIO buffer, clear and
4804 * validate only the previously invalid portions of the buffer.
4805 * This routine essentially fakes an I/O, so we need to clear
4806 * BIO_ERROR and B_INVAL.
4808 * Note that while we only theoretically need to clear through b_bcount,
4809 * we go ahead and clear through b_bufsize.
4812 vfs_bio_clrbuf(struct buf *bp)
4814 int i, j, mask, sa, ea, slide;
4816 if ((bp->b_flags & (B_VMIO | B_MALLOC)) != B_VMIO) {
4820 bp->b_flags &= ~B_INVAL;
4821 bp->b_ioflags &= ~BIO_ERROR;
4822 vfs_busy_pages_acquire(bp);
4823 sa = bp->b_offset & PAGE_MASK;
4825 for (i = 0; i < bp->b_npages; i++, sa = 0) {
4826 slide = imin(slide + PAGE_SIZE, bp->b_offset + bp->b_bufsize);
4827 ea = slide & PAGE_MASK;
4830 if (bp->b_pages[i] == bogus_page)
4833 mask = ((1 << ((ea - sa) / DEV_BSIZE)) - 1) << j;
4834 if ((bp->b_pages[i]->valid & mask) == mask)
4836 if ((bp->b_pages[i]->valid & mask) == 0)
4837 pmap_zero_page_area(bp->b_pages[i], sa, ea - sa);
4839 for (; sa < ea; sa += DEV_BSIZE, j++) {
4840 if ((bp->b_pages[i]->valid & (1 << j)) == 0) {
4841 pmap_zero_page_area(bp->b_pages[i],
4846 vm_page_set_valid_range(bp->b_pages[i], j * DEV_BSIZE,
4847 roundup2(ea - sa, DEV_BSIZE));
4849 vfs_busy_pages_release(bp);
4854 vfs_bio_bzero_buf(struct buf *bp, int base, int size)
4859 if (buf_mapped(bp)) {
4860 BUF_CHECK_MAPPED(bp);
4861 bzero(bp->b_data + base, size);
4863 BUF_CHECK_UNMAPPED(bp);
4864 n = PAGE_SIZE - (base & PAGE_MASK);
4865 for (i = base / PAGE_SIZE; size > 0 && i < bp->b_npages; ++i) {
4869 pmap_zero_page_area(m, base & PAGE_MASK, n);
4878 * Update buffer flags based on I/O request parameters, optionally releasing the
4879 * buffer. If it's VMIO or direct I/O, the buffer pages are released to the VM,
4880 * where they may be placed on a page queue (VMIO) or freed immediately (direct
4881 * I/O). Otherwise the buffer is released to the cache.
4884 b_io_dismiss(struct buf *bp, int ioflag, bool release)
4887 KASSERT((ioflag & IO_NOREUSE) == 0 || (ioflag & IO_VMIO) != 0,
4888 ("buf %p non-VMIO noreuse", bp));
4890 if ((ioflag & IO_DIRECT) != 0)
4891 bp->b_flags |= B_DIRECT;
4892 if ((ioflag & IO_EXT) != 0)
4893 bp->b_xflags |= BX_ALTDATA;
4894 if ((ioflag & (IO_VMIO | IO_DIRECT)) != 0 && LIST_EMPTY(&bp->b_dep)) {
4895 bp->b_flags |= B_RELBUF;
4896 if ((ioflag & IO_NOREUSE) != 0)
4897 bp->b_flags |= B_NOREUSE;
4905 vfs_bio_brelse(struct buf *bp, int ioflag)
4908 b_io_dismiss(bp, ioflag, true);
4912 vfs_bio_set_flags(struct buf *bp, int ioflag)
4915 b_io_dismiss(bp, ioflag, false);
4919 * vm_hold_load_pages and vm_hold_free_pages get pages into
4920 * a buffers address space. The pages are anonymous and are
4921 * not associated with a file object.
4924 vm_hold_load_pages(struct buf *bp, vm_offset_t from, vm_offset_t to)
4930 BUF_CHECK_MAPPED(bp);
4932 to = round_page(to);
4933 from = round_page(from);
4934 index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT;
4935 MPASS((bp->b_flags & B_MAXPHYS) == 0);
4936 KASSERT(to - from <= maxbcachebuf,
4937 ("vm_hold_load_pages too large %p %#jx %#jx %u",
4938 bp, (uintmax_t)from, (uintmax_t)to, maxbcachebuf));
4940 for (pg = from; pg < to; pg += PAGE_SIZE, index++) {
4942 * note: must allocate system pages since blocking here
4943 * could interfere with paging I/O, no matter which
4946 p = vm_page_alloc_noobj(VM_ALLOC_SYSTEM | VM_ALLOC_WIRED |
4947 VM_ALLOC_COUNT((to - pg) >> PAGE_SHIFT) | VM_ALLOC_WAITOK);
4948 pmap_qenter(pg, &p, 1);
4949 bp->b_pages[index] = p;
4951 bp->b_npages = index;
4954 /* Return pages associated with this buf to the vm system */
4956 vm_hold_free_pages(struct buf *bp, int newbsize)
4960 int index, newnpages;
4962 BUF_CHECK_MAPPED(bp);
4964 from = round_page((vm_offset_t)bp->b_data + newbsize);
4965 newnpages = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT;
4966 if (bp->b_npages > newnpages)
4967 pmap_qremove(from, bp->b_npages - newnpages);
4968 for (index = newnpages; index < bp->b_npages; index++) {
4969 p = bp->b_pages[index];
4970 bp->b_pages[index] = NULL;
4971 vm_page_unwire_noq(p);
4974 bp->b_npages = newnpages;
4978 * Map an IO request into kernel virtual address space.
4980 * All requests are (re)mapped into kernel VA space.
4981 * Notice that we use b_bufsize for the size of the buffer
4982 * to be mapped. b_bcount might be modified by the driver.
4984 * Note that even if the caller determines that the address space should
4985 * be valid, a race or a smaller-file mapped into a larger space may
4986 * actually cause vmapbuf() to fail, so all callers of vmapbuf() MUST
4987 * check the return value.
4989 * This function only works with pager buffers.
4992 vmapbuf(struct buf *bp, void *uaddr, size_t len, int mapbuf)
4997 MPASS((bp->b_flags & B_MAXPHYS) != 0);
4998 prot = VM_PROT_READ;
4999 if (bp->b_iocmd == BIO_READ)
5000 prot |= VM_PROT_WRITE; /* Less backwards than it looks */
5001 pidx = vm_fault_quick_hold_pages(&curproc->p_vmspace->vm_map,
5002 (vm_offset_t)uaddr, len, prot, bp->b_pages, PBUF_PAGES);
5005 bp->b_bufsize = len;
5006 bp->b_npages = pidx;
5007 bp->b_offset = ((vm_offset_t)uaddr) & PAGE_MASK;
5008 if (mapbuf || !unmapped_buf_allowed) {
5009 pmap_qenter((vm_offset_t)bp->b_kvabase, bp->b_pages, pidx);
5010 bp->b_data = bp->b_kvabase + bp->b_offset;
5012 bp->b_data = unmapped_buf;
5017 * Free the io map PTEs associated with this IO operation.
5018 * We also invalidate the TLB entries and restore the original b_addr.
5020 * This function only works with pager buffers.
5023 vunmapbuf(struct buf *bp)
5027 npages = bp->b_npages;
5029 pmap_qremove(trunc_page((vm_offset_t)bp->b_data), npages);
5030 vm_page_unhold_pages(bp->b_pages, npages);
5032 bp->b_data = unmapped_buf;
5036 bdone(struct buf *bp)
5040 mtxp = mtx_pool_find(mtxpool_sleep, bp);
5042 bp->b_flags |= B_DONE;
5048 bwait(struct buf *bp, u_char pri, const char *wchan)
5052 mtxp = mtx_pool_find(mtxpool_sleep, bp);
5054 while ((bp->b_flags & B_DONE) == 0)
5055 msleep(bp, mtxp, pri, wchan, 0);
5060 bufsync(struct bufobj *bo, int waitfor)
5063 return (VOP_FSYNC(bo2vnode(bo), waitfor, curthread));
5067 bufstrategy(struct bufobj *bo, struct buf *bp)
5073 KASSERT(vp == bo->bo_private, ("Inconsistent vnode bufstrategy"));
5074 KASSERT(vp->v_type != VCHR && vp->v_type != VBLK,
5075 ("Wrong vnode in bufstrategy(bp=%p, vp=%p)", bp, vp));
5076 i = VOP_STRATEGY(vp, bp);
5077 KASSERT(i == 0, ("VOP_STRATEGY failed bp=%p vp=%p", bp, bp->b_vp));
5081 * Initialize a struct bufobj before use. Memory is assumed zero filled.
5084 bufobj_init(struct bufobj *bo, void *private)
5086 static volatile int bufobj_cleanq;
5089 atomic_fetchadd_int(&bufobj_cleanq, 1) % buf_domains;
5090 rw_init(BO_LOCKPTR(bo), "bufobj interlock");
5091 bo->bo_private = private;
5092 TAILQ_INIT(&bo->bo_clean.bv_hd);
5093 TAILQ_INIT(&bo->bo_dirty.bv_hd);
5097 bufobj_wrefl(struct bufobj *bo)
5100 KASSERT(bo != NULL, ("NULL bo in bufobj_wref"));
5101 ASSERT_BO_WLOCKED(bo);
5106 bufobj_wref(struct bufobj *bo)
5109 KASSERT(bo != NULL, ("NULL bo in bufobj_wref"));
5116 bufobj_wdrop(struct bufobj *bo)
5119 KASSERT(bo != NULL, ("NULL bo in bufobj_wdrop"));
5121 KASSERT(bo->bo_numoutput > 0, ("bufobj_wdrop non-positive count"));
5122 if ((--bo->bo_numoutput == 0) && (bo->bo_flag & BO_WWAIT)) {
5123 bo->bo_flag &= ~BO_WWAIT;
5124 wakeup(&bo->bo_numoutput);
5130 bufobj_wwait(struct bufobj *bo, int slpflag, int timeo)
5134 KASSERT(bo != NULL, ("NULL bo in bufobj_wwait"));
5135 ASSERT_BO_WLOCKED(bo);
5137 while (bo->bo_numoutput) {
5138 bo->bo_flag |= BO_WWAIT;
5139 error = msleep(&bo->bo_numoutput, BO_LOCKPTR(bo),
5140 slpflag | (PRIBIO + 1), "bo_wwait", timeo);
5148 * Set bio_data or bio_ma for struct bio from the struct buf.
5151 bdata2bio(struct buf *bp, struct bio *bip)
5154 if (!buf_mapped(bp)) {
5155 KASSERT(unmapped_buf_allowed, ("unmapped"));
5156 bip->bio_ma = bp->b_pages;
5157 bip->bio_ma_n = bp->b_npages;
5158 bip->bio_data = unmapped_buf;
5159 bip->bio_ma_offset = (vm_offset_t)bp->b_offset & PAGE_MASK;
5160 bip->bio_flags |= BIO_UNMAPPED;
5161 KASSERT(round_page(bip->bio_ma_offset + bip->bio_length) /
5162 PAGE_SIZE == bp->b_npages,
5163 ("Buffer %p too short: %d %lld %d", bp, bip->bio_ma_offset,
5164 (long long)bip->bio_length, bip->bio_ma_n));
5166 bip->bio_data = bp->b_data;
5172 * The MIPS pmap code currently doesn't handle aliased pages.
5173 * The VIPT caches may not handle page aliasing themselves, leading
5174 * to data corruption.
5176 * As such, this code makes a system extremely unhappy if said
5177 * system doesn't support unaliasing the above situation in hardware.
5178 * Some "recent" systems (eg some mips24k/mips74k cores) don't enable
5179 * this feature at build time, so it has to be handled in software.
5181 * Once the MIPS pmap/cache code grows to support this function on
5182 * earlier chips, it should be flipped back off.
5185 static int buf_pager_relbuf = 1;
5187 static int buf_pager_relbuf = 0;
5189 SYSCTL_INT(_vfs, OID_AUTO, buf_pager_relbuf, CTLFLAG_RWTUN,
5190 &buf_pager_relbuf, 0,
5191 "Make buffer pager release buffers after reading");
5194 * The buffer pager. It uses buffer reads to validate pages.
5196 * In contrast to the generic local pager from vm/vnode_pager.c, this
5197 * pager correctly and easily handles volumes where the underlying
5198 * device block size is greater than the machine page size. The
5199 * buffer cache transparently extends the requested page run to be
5200 * aligned at the block boundary, and does the necessary bogus page
5201 * replacements in the addends to avoid obliterating already valid
5204 * The only non-trivial issue is that the exclusive busy state for
5205 * pages, which is assumed by the vm_pager_getpages() interface, is
5206 * incompatible with the VMIO buffer cache's desire to share-busy the
5207 * pages. This function performs a trivial downgrade of the pages'
5208 * state before reading buffers, and a less trivial upgrade from the
5209 * shared-busy to excl-busy state after the read.
5212 vfs_bio_getpages(struct vnode *vp, vm_page_t *ma, int count,
5213 int *rbehind, int *rahead, vbg_get_lblkno_t get_lblkno,
5214 vbg_get_blksize_t get_blksize)
5221 vm_ooffset_t la, lb, poff, poffe;
5223 int br_flags, error, i, pgsin, pgsin_a, pgsin_b;
5226 object = vp->v_object;
5229 la = IDX_TO_OFF(ma[count - 1]->pindex);
5230 if (la >= object->un_pager.vnp.vnp_size)
5231 return (VM_PAGER_BAD);
5234 * Change the meaning of la from where the last requested page starts
5235 * to where it ends, because that's the end of the requested region
5236 * and the start of the potential read-ahead region.
5239 lpart = la > object->un_pager.vnp.vnp_size;
5240 error = get_blksize(vp, get_lblkno(vp, IDX_TO_OFF(ma[0]->pindex)),
5243 return (VM_PAGER_ERROR);
5246 * Calculate read-ahead, behind and total pages.
5249 lb = IDX_TO_OFF(ma[0]->pindex);
5250 pgsin_b = OFF_TO_IDX(lb - rounddown2(lb, bo_bs));
5252 if (rbehind != NULL)
5254 pgsin_a = OFF_TO_IDX(roundup2(la, bo_bs) - la);
5255 if (la + IDX_TO_OFF(pgsin_a) >= object->un_pager.vnp.vnp_size)
5256 pgsin_a = OFF_TO_IDX(roundup2(object->un_pager.vnp.vnp_size,
5261 VM_CNT_INC(v_vnodein);
5262 VM_CNT_ADD(v_vnodepgsin, pgsin);
5264 br_flags = (mp != NULL && (mp->mnt_kern_flag & MNTK_UNMAPPED_BUFS)
5265 != 0) ? GB_UNMAPPED : 0;
5267 for (i = 0; i < count; i++) {
5268 if (ma[i] != bogus_page)
5269 vm_page_busy_downgrade(ma[i]);
5273 for (i = 0; i < count; i++) {
5275 if (m == bogus_page)
5279 * Pages are shared busy and the object lock is not
5280 * owned, which together allow for the pages'
5281 * invalidation. The racy test for validity avoids
5282 * useless creation of the buffer for the most typical
5283 * case when invalidation is not used in redo or for
5284 * parallel read. The shared->excl upgrade loop at
5285 * the end of the function catches the race in a
5286 * reliable way (protected by the object lock).
5288 if (vm_page_all_valid(m))
5291 poff = IDX_TO_OFF(m->pindex);
5292 poffe = MIN(poff + PAGE_SIZE, object->un_pager.vnp.vnp_size);
5293 for (; poff < poffe; poff += bsize) {
5294 lbn = get_lblkno(vp, poff);
5299 error = get_blksize(vp, lbn, &bsize);
5301 error = bread_gb(vp, lbn, bsize,
5302 curthread->td_ucred, br_flags, &bp);
5305 if (bp->b_rcred == curthread->td_ucred) {
5306 crfree(bp->b_rcred);
5307 bp->b_rcred = NOCRED;
5309 if (LIST_EMPTY(&bp->b_dep)) {
5311 * Invalidation clears m->valid, but
5312 * may leave B_CACHE flag if the
5313 * buffer existed at the invalidation
5314 * time. In this case, recycle the
5315 * buffer to do real read on next
5316 * bread() after redo.
5318 * Otherwise B_RELBUF is not strictly
5319 * necessary, enable to reduce buf
5322 if (buf_pager_relbuf ||
5323 !vm_page_all_valid(m))
5324 bp->b_flags |= B_RELBUF;
5326 bp->b_flags &= ~B_NOCACHE;
5332 KASSERT(1 /* racy, enable for debugging */ ||
5333 vm_page_all_valid(m) || i == count - 1,
5334 ("buf %d %p invalid", i, m));
5335 if (i == count - 1 && lpart) {
5336 if (!vm_page_none_valid(m) &&
5337 !vm_page_all_valid(m))
5338 vm_page_zero_invalid(m, TRUE);
5345 for (i = 0; i < count; i++) {
5346 if (ma[i] == bogus_page)
5348 if (vm_page_busy_tryupgrade(ma[i]) == 0) {
5349 vm_page_sunbusy(ma[i]);
5350 ma[i] = vm_page_grab_unlocked(object, ma[i]->pindex,
5355 * Since the pages were only sbusy while neither the
5356 * buffer nor the object lock was held by us, or
5357 * reallocated while vm_page_grab() slept for busy
5358 * relinguish, they could have been invalidated.
5359 * Recheck the valid bits and re-read as needed.
5361 * Note that the last page is made fully valid in the
5362 * read loop, and partial validity for the page at
5363 * index count - 1 could mean that the page was
5364 * invalidated or removed, so we must restart for
5367 if (!vm_page_all_valid(ma[i]))
5370 if (redo && error == 0)
5372 return (error != 0 ? VM_PAGER_ERROR : VM_PAGER_OK);
5375 #include "opt_ddb.h"
5377 #include <ddb/ddb.h>
5379 /* DDB command to show buffer data */
5380 DB_SHOW_COMMAND(buffer, db_show_buffer)
5383 struct buf *bp = (struct buf *)addr;
5384 #ifdef FULL_BUF_TRACKING
5389 db_printf("usage: show buffer <addr>\n");
5393 db_printf("buf at %p\n", bp);
5394 db_printf("b_flags = 0x%b, b_xflags=0x%b\n",
5395 (u_int)bp->b_flags, PRINT_BUF_FLAGS,
5396 (u_int)bp->b_xflags, PRINT_BUF_XFLAGS);
5397 db_printf("b_vflags=0x%b b_ioflags0x%b\n",
5398 (u_int)bp->b_vflags, PRINT_BUF_VFLAGS,
5399 (u_int)bp->b_ioflags, PRINT_BIO_FLAGS);
5401 "b_error = %d, b_bufsize = %ld, b_bcount = %ld, b_resid = %ld\n"
5402 "b_bufobj = (%p), b_data = %p\n, b_blkno = %jd, b_lblkno = %jd, "
5403 "b_vp = %p, b_dep = %p\n",
5404 bp->b_error, bp->b_bufsize, bp->b_bcount, bp->b_resid,
5405 bp->b_bufobj, bp->b_data, (intmax_t)bp->b_blkno,
5406 (intmax_t)bp->b_lblkno, bp->b_vp, bp->b_dep.lh_first);
5407 db_printf("b_kvabase = %p, b_kvasize = %d\n",
5408 bp->b_kvabase, bp->b_kvasize);
5411 db_printf("b_npages = %d, pages(OBJ, IDX, PA): ", bp->b_npages);
5412 for (i = 0; i < bp->b_npages; i++) {
5416 db_printf("(%p, 0x%lx, 0x%lx)", m->object,
5418 (u_long)VM_PAGE_TO_PHYS(m));
5420 db_printf("( ??? )");
5421 if ((i + 1) < bp->b_npages)
5426 BUF_LOCKPRINTINFO(bp);
5427 #if defined(FULL_BUF_TRACKING)
5428 db_printf("b_io_tracking: b_io_tcnt = %u\n", bp->b_io_tcnt);
5430 i = bp->b_io_tcnt % BUF_TRACKING_SIZE;
5431 for (j = 1; j <= BUF_TRACKING_SIZE; j++) {
5432 if (bp->b_io_tracking[BUF_TRACKING_ENTRY(i - j)] == NULL)
5434 db_printf(" %2u: %s\n", j,
5435 bp->b_io_tracking[BUF_TRACKING_ENTRY(i - j)]);
5437 #elif defined(BUF_TRACKING)
5438 db_printf("b_io_tracking: %s\n", bp->b_io_tracking);
5443 DB_SHOW_COMMAND(bufqueues, bufqueues)
5445 struct bufdomain *bd;
5450 db_printf("bqempty: %d\n", bqempty.bq_len);
5452 for (i = 0; i < buf_domains; i++) {
5454 db_printf("Buf domain %d\n", i);
5455 db_printf("\tfreebufs\t%d\n", bd->bd_freebuffers);
5456 db_printf("\tlofreebufs\t%d\n", bd->bd_lofreebuffers);
5457 db_printf("\thifreebufs\t%d\n", bd->bd_hifreebuffers);
5459 db_printf("\tbufspace\t%ld\n", bd->bd_bufspace);
5460 db_printf("\tmaxbufspace\t%ld\n", bd->bd_maxbufspace);
5461 db_printf("\thibufspace\t%ld\n", bd->bd_hibufspace);
5462 db_printf("\tlobufspace\t%ld\n", bd->bd_lobufspace);
5463 db_printf("\tbufspacethresh\t%ld\n", bd->bd_bufspacethresh);
5465 db_printf("\tnumdirtybuffers\t%d\n", bd->bd_numdirtybuffers);
5466 db_printf("\tlodirtybuffers\t%d\n", bd->bd_lodirtybuffers);
5467 db_printf("\thidirtybuffers\t%d\n", bd->bd_hidirtybuffers);
5468 db_printf("\tdirtybufthresh\t%d\n", bd->bd_dirtybufthresh);
5471 TAILQ_FOREACH(bp, &bd->bd_cleanq->bq_queue, b_freelist)
5472 total += bp->b_bufsize;
5473 db_printf("\tcleanq count\t%d (%ld)\n",
5474 bd->bd_cleanq->bq_len, total);
5476 TAILQ_FOREACH(bp, &bd->bd_dirtyq.bq_queue, b_freelist)
5477 total += bp->b_bufsize;
5478 db_printf("\tdirtyq count\t%d (%ld)\n",
5479 bd->bd_dirtyq.bq_len, total);
5480 db_printf("\twakeup\t\t%d\n", bd->bd_wanted);
5481 db_printf("\tlim\t\t%d\n", bd->bd_lim);
5482 db_printf("\tCPU ");
5483 for (j = 0; j <= mp_maxid; j++)
5484 db_printf("%d, ", bd->bd_subq[j].bq_len);
5488 for (j = 0; j < nbuf; j++) {
5490 if (bp->b_domain == i && BUF_ISLOCKED(bp)) {
5492 total += bp->b_bufsize;
5495 db_printf("\tLocked buffers: %d space %ld\n", cnt, total);
5498 for (j = 0; j < nbuf; j++) {
5500 if (bp->b_domain == i) {
5502 total += bp->b_bufsize;
5505 db_printf("\tTotal buffers: %d space %ld\n", cnt, total);
5509 DB_SHOW_COMMAND(lockedbufs, lockedbufs)
5514 for (i = 0; i < nbuf; i++) {
5516 if (BUF_ISLOCKED(bp)) {
5517 db_show_buffer((uintptr_t)bp, 1, 0, NULL);
5525 DB_SHOW_COMMAND(vnodebufs, db_show_vnodebufs)
5531 db_printf("usage: show vnodebufs <addr>\n");
5534 vp = (struct vnode *)addr;
5535 db_printf("Clean buffers:\n");
5536 TAILQ_FOREACH(bp, &vp->v_bufobj.bo_clean.bv_hd, b_bobufs) {
5537 db_show_buffer((uintptr_t)bp, 1, 0, NULL);
5540 db_printf("Dirty buffers:\n");
5541 TAILQ_FOREACH(bp, &vp->v_bufobj.bo_dirty.bv_hd, b_bobufs) {
5542 db_show_buffer((uintptr_t)bp, 1, 0, NULL);
5547 DB_COMMAND(countfreebufs, db_coundfreebufs)
5550 int i, used = 0, nfree = 0;
5553 db_printf("usage: countfreebufs\n");
5557 for (i = 0; i < nbuf; i++) {
5559 if (bp->b_qindex == QUEUE_EMPTY)
5565 db_printf("Counted %d free, %d used (%d tot)\n", nfree, used,
5567 db_printf("numfreebuffers is %d\n", numfreebuffers);