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;
1049 * With KASAN enabled, the kernel map is shadowed. Account for this
1050 * when sizing maps based on the amount of physical memory available.
1052 physmem_est = (physmem_est * KASAN_SHADOW_SCALE) /
1053 (KASAN_SHADOW_SCALE + 1);
1057 * physmem_est is in pages. Convert it to kilobytes (assumes
1058 * PAGE_SIZE is >= 1K)
1060 physmem_est = physmem_est * (PAGE_SIZE / 1024);
1062 maxbcachebuf_adjust();
1064 * The nominal buffer size (and minimum KVA allocation) is BKVASIZE.
1065 * For the first 64MB of ram nominally allocate sufficient buffers to
1066 * cover 1/4 of our ram. Beyond the first 64MB allocate additional
1067 * buffers to cover 1/10 of our ram over 64MB. When auto-sizing
1068 * the buffer cache we limit the eventual kva reservation to
1071 * factor represents the 1/4 x ram conversion.
1074 int factor = 4 * BKVASIZE / 1024;
1077 if (physmem_est > 4096)
1078 nbuf += min((physmem_est - 4096) / factor,
1080 if (physmem_est > 65536)
1081 nbuf += min((physmem_est - 65536) * 2 / (factor * 5),
1082 32 * 1024 * 1024 / (factor * 5));
1084 if (maxbcache && nbuf > maxbcache / BKVASIZE)
1085 nbuf = maxbcache / BKVASIZE;
1090 /* XXX Avoid unsigned long overflows later on with maxbufspace. */
1091 maxbuf = (LONG_MAX / 3) / BKVASIZE;
1092 if (nbuf > maxbuf) {
1094 printf("Warning: nbufs lowered from %d to %ld\n", nbuf,
1100 * Ideal allocation size for the transient bio submap is 10%
1101 * of the maximal space buffer map. This roughly corresponds
1102 * to the amount of the buffer mapped for typical UFS load.
1104 * Clip the buffer map to reserve space for the transient
1105 * BIOs, if its extent is bigger than 90% (80% on i386) of the
1106 * maximum buffer map extent on the platform.
1108 * The fall-back to the maxbuf in case of maxbcache unset,
1109 * allows to not trim the buffer KVA for the architectures
1110 * with ample KVA space.
1112 if (bio_transient_maxcnt == 0 && unmapped_buf_allowed) {
1113 maxbuf_sz = maxbcache != 0 ? maxbcache : maxbuf * BKVASIZE;
1114 buf_sz = (long)nbuf * BKVASIZE;
1115 if (buf_sz < maxbuf_sz / TRANSIENT_DENOM *
1116 (TRANSIENT_DENOM - 1)) {
1118 * There is more KVA than memory. Do not
1119 * adjust buffer map size, and assign the rest
1120 * of maxbuf to transient map.
1122 biotmap_sz = maxbuf_sz - buf_sz;
1125 * Buffer map spans all KVA we could afford on
1126 * this platform. Give 10% (20% on i386) of
1127 * the buffer map to the transient bio map.
1129 biotmap_sz = buf_sz / TRANSIENT_DENOM;
1130 buf_sz -= biotmap_sz;
1132 if (biotmap_sz / INT_MAX > maxphys)
1133 bio_transient_maxcnt = INT_MAX;
1135 bio_transient_maxcnt = biotmap_sz / maxphys;
1137 * Artificially limit to 1024 simultaneous in-flight I/Os
1138 * using the transient mapping.
1140 if (bio_transient_maxcnt > 1024)
1141 bio_transient_maxcnt = 1024;
1143 nbuf = buf_sz / BKVASIZE;
1147 nswbuf = min(nbuf / 4, 256);
1148 if (nswbuf < NSWBUF_MIN)
1149 nswbuf = NSWBUF_MIN;
1153 * Reserve space for the buffer cache buffers
1156 v = (caddr_t)buf + (sizeof(struct buf) + sizeof(vm_page_t) *
1157 atop(maxbcachebuf)) * nbuf;
1162 /* Initialize the buffer subsystem. Called before use of any buffers. */
1169 KASSERT(maxbcachebuf >= MAXBSIZE,
1170 ("maxbcachebuf (%d) must be >= MAXBSIZE (%d)\n", maxbcachebuf,
1172 bq_init(&bqempty, QUEUE_EMPTY, -1, "bufq empty lock");
1173 mtx_init(&rbreqlock, "runningbufspace lock", NULL, MTX_DEF);
1174 mtx_init(&bdlock, "buffer daemon lock", NULL, MTX_DEF);
1175 mtx_init(&bdirtylock, "dirty buf lock", NULL, MTX_DEF);
1177 unmapped_buf = (caddr_t)kva_alloc(maxphys);
1179 /* finally, initialize each buffer header and stick on empty q */
1180 for (i = 0; i < nbuf; i++) {
1182 bzero(bp, sizeof(*bp) + sizeof(vm_page_t) * atop(maxbcachebuf));
1183 bp->b_flags = B_INVAL;
1184 bp->b_rcred = NOCRED;
1185 bp->b_wcred = NOCRED;
1186 bp->b_qindex = QUEUE_NONE;
1188 bp->b_subqueue = mp_maxid + 1;
1190 bp->b_data = bp->b_kvabase = unmapped_buf;
1191 LIST_INIT(&bp->b_dep);
1193 bq_insert(&bqempty, bp, false);
1197 * maxbufspace is the absolute maximum amount of buffer space we are
1198 * allowed to reserve in KVM and in real terms. The absolute maximum
1199 * is nominally used by metadata. hibufspace is the nominal maximum
1200 * used by most other requests. The differential is required to
1201 * ensure that metadata deadlocks don't occur.
1203 * maxbufspace is based on BKVASIZE. Allocating buffers larger then
1204 * this may result in KVM fragmentation which is not handled optimally
1205 * by the system. XXX This is less true with vmem. We could use
1208 maxbufspace = (long)nbuf * BKVASIZE;
1209 hibufspace = lmax(3 * maxbufspace / 4, maxbufspace - maxbcachebuf * 10);
1210 lobufspace = (hibufspace / 20) * 19; /* 95% */
1211 bufspacethresh = lobufspace + (hibufspace - lobufspace) / 2;
1214 * Note: The 16 MiB upper limit for hirunningspace was chosen
1215 * arbitrarily and may need further tuning. It corresponds to
1216 * 128 outstanding write IO requests (if IO size is 128 KiB),
1217 * which fits with many RAID controllers' tagged queuing limits.
1218 * The lower 1 MiB limit is the historical upper limit for
1221 hirunningspace = lmax(lmin(roundup(hibufspace / 64, maxbcachebuf),
1222 16 * 1024 * 1024), 1024 * 1024);
1223 lorunningspace = roundup((hirunningspace * 2) / 3, maxbcachebuf);
1226 * Limit the amount of malloc memory since it is wired permanently into
1227 * the kernel space. Even though this is accounted for in the buffer
1228 * allocation, we don't want the malloced region to grow uncontrolled.
1229 * The malloc scheme improves memory utilization significantly on
1230 * average (small) directories.
1232 maxbufmallocspace = hibufspace / 20;
1235 * Reduce the chance of a deadlock occurring by limiting the number
1236 * of delayed-write dirty buffers we allow to stack up.
1238 hidirtybuffers = nbuf / 4 + 20;
1239 dirtybufthresh = hidirtybuffers * 9 / 10;
1241 * To support extreme low-memory systems, make sure hidirtybuffers
1242 * cannot eat up all available buffer space. This occurs when our
1243 * minimum cannot be met. We try to size hidirtybuffers to 3/4 our
1244 * buffer space assuming BKVASIZE'd buffers.
1246 while ((long)hidirtybuffers * BKVASIZE > 3 * hibufspace / 4) {
1247 hidirtybuffers >>= 1;
1249 lodirtybuffers = hidirtybuffers / 2;
1252 * lofreebuffers should be sufficient to avoid stalling waiting on
1253 * buf headers under heavy utilization. The bufs in per-cpu caches
1254 * are counted as free but will be unavailable to threads executing
1257 * hifreebuffers is the free target for the bufspace daemon. This
1258 * should be set appropriately to limit work per-iteration.
1260 lofreebuffers = MIN((nbuf / 25) + (20 * mp_ncpus), 128 * mp_ncpus);
1261 hifreebuffers = (3 * lofreebuffers) / 2;
1262 numfreebuffers = nbuf;
1264 /* Setup the kva and free list allocators. */
1265 vmem_set_reclaim(buffer_arena, bufkva_reclaim);
1266 buf_zone = uma_zcache_create("buf free cache",
1267 sizeof(struct buf) + sizeof(vm_page_t) * atop(maxbcachebuf),
1268 NULL, NULL, NULL, NULL, buf_import, buf_release, NULL, 0);
1271 * Size the clean queue according to the amount of buffer space.
1272 * One queue per-256mb up to the max. More queues gives better
1273 * concurrency but less accurate LRU.
1275 buf_domains = MIN(howmany(maxbufspace, 256*1024*1024), BUF_DOMAINS);
1276 for (i = 0 ; i < buf_domains; i++) {
1277 struct bufdomain *bd;
1281 bd->bd_freebuffers = nbuf / buf_domains;
1282 bd->bd_hifreebuffers = hifreebuffers / buf_domains;
1283 bd->bd_lofreebuffers = lofreebuffers / buf_domains;
1284 bd->bd_bufspace = 0;
1285 bd->bd_maxbufspace = maxbufspace / buf_domains;
1286 bd->bd_hibufspace = hibufspace / buf_domains;
1287 bd->bd_lobufspace = lobufspace / buf_domains;
1288 bd->bd_bufspacethresh = bufspacethresh / buf_domains;
1289 bd->bd_numdirtybuffers = 0;
1290 bd->bd_hidirtybuffers = hidirtybuffers / buf_domains;
1291 bd->bd_lodirtybuffers = lodirtybuffers / buf_domains;
1292 bd->bd_dirtybufthresh = dirtybufthresh / buf_domains;
1293 /* Don't allow more than 2% of bufs in the per-cpu caches. */
1294 bd->bd_lim = nbuf / buf_domains / 50 / mp_ncpus;
1296 getnewbufcalls = counter_u64_alloc(M_WAITOK);
1297 getnewbufrestarts = counter_u64_alloc(M_WAITOK);
1298 mappingrestarts = counter_u64_alloc(M_WAITOK);
1299 numbufallocfails = counter_u64_alloc(M_WAITOK);
1300 notbufdflushes = counter_u64_alloc(M_WAITOK);
1301 buffreekvacnt = counter_u64_alloc(M_WAITOK);
1302 bufdefragcnt = counter_u64_alloc(M_WAITOK);
1303 bufkvaspace = counter_u64_alloc(M_WAITOK);
1308 vfs_buf_check_mapped(struct buf *bp)
1311 KASSERT(bp->b_kvabase != unmapped_buf,
1312 ("mapped buf: b_kvabase was not updated %p", bp));
1313 KASSERT(bp->b_data != unmapped_buf,
1314 ("mapped buf: b_data was not updated %p", bp));
1315 KASSERT(bp->b_data < unmapped_buf || bp->b_data >= unmapped_buf +
1316 maxphys, ("b_data + b_offset unmapped %p", bp));
1320 vfs_buf_check_unmapped(struct buf *bp)
1323 KASSERT(bp->b_data == unmapped_buf,
1324 ("unmapped buf: corrupted b_data %p", bp));
1327 #define BUF_CHECK_MAPPED(bp) vfs_buf_check_mapped(bp)
1328 #define BUF_CHECK_UNMAPPED(bp) vfs_buf_check_unmapped(bp)
1330 #define BUF_CHECK_MAPPED(bp) do {} while (0)
1331 #define BUF_CHECK_UNMAPPED(bp) do {} while (0)
1335 isbufbusy(struct buf *bp)
1337 if (((bp->b_flags & B_INVAL) == 0 && BUF_ISLOCKED(bp)) ||
1338 ((bp->b_flags & (B_DELWRI | B_INVAL)) == B_DELWRI))
1344 * Shutdown the system cleanly to prepare for reboot, halt, or power off.
1347 bufshutdown(int show_busybufs)
1349 static int first_buf_printf = 1;
1351 int i, iter, nbusy, pbusy;
1357 * Sync filesystems for shutdown
1359 wdog_kern_pat(WD_LASTVAL);
1360 kern_sync(curthread);
1363 * With soft updates, some buffers that are
1364 * written will be remarked as dirty until other
1365 * buffers are written.
1367 for (iter = pbusy = 0; iter < 20; iter++) {
1369 for (i = nbuf - 1; i >= 0; i--) {
1375 if (first_buf_printf)
1376 printf("All buffers synced.");
1379 if (first_buf_printf) {
1380 printf("Syncing disks, buffers remaining... ");
1381 first_buf_printf = 0;
1383 printf("%d ", nbusy);
1388 wdog_kern_pat(WD_LASTVAL);
1389 kern_sync(curthread);
1393 * Spin for a while to allow interrupt threads to run.
1395 DELAY(50000 * iter);
1398 * Context switch several times to allow interrupt
1401 for (subiter = 0; subiter < 50 * iter; subiter++) {
1402 thread_lock(curthread);
1410 * Count only busy local buffers to prevent forcing
1411 * a fsck if we're just a client of a wedged NFS server
1414 for (i = nbuf - 1; i >= 0; i--) {
1416 if (isbufbusy(bp)) {
1418 /* XXX: This is bogus. We should probably have a BO_REMOTE flag instead */
1419 if (bp->b_dev == NULL) {
1420 TAILQ_REMOVE(&mountlist,
1421 bp->b_vp->v_mount, mnt_list);
1426 if (show_busybufs > 0) {
1428 "%d: buf:%p, vnode:%p, flags:%0x, blkno:%jd, lblkno:%jd, buflock:",
1429 nbusy, bp, bp->b_vp, bp->b_flags,
1430 (intmax_t)bp->b_blkno,
1431 (intmax_t)bp->b_lblkno);
1432 BUF_LOCKPRINTINFO(bp);
1433 if (show_busybufs > 1)
1441 * Failed to sync all blocks. Indicate this and don't
1442 * unmount filesystems (thus forcing an fsck on reboot).
1444 printf("Giving up on %d buffers\n", nbusy);
1445 DELAY(5000000); /* 5 seconds */
1448 if (!first_buf_printf)
1449 printf("Final sync complete\n");
1452 * Unmount filesystems. Swapoff before unmount,
1453 * because file-backed swap is non-operational after unmount
1454 * of the underlying filesystem.
1456 if (!KERNEL_PANICKED()) {
1461 DELAY(100000); /* wait for console output to finish */
1465 bpmap_qenter(struct buf *bp)
1468 BUF_CHECK_MAPPED(bp);
1471 * bp->b_data is relative to bp->b_offset, but
1472 * bp->b_offset may be offset into the first page.
1474 bp->b_data = (caddr_t)trunc_page((vm_offset_t)bp->b_data);
1475 pmap_qenter((vm_offset_t)bp->b_data, bp->b_pages, bp->b_npages);
1476 bp->b_data = (caddr_t)((vm_offset_t)bp->b_data |
1477 (vm_offset_t)(bp->b_offset & PAGE_MASK));
1480 static inline struct bufdomain *
1481 bufdomain(struct buf *bp)
1484 return (&bdomain[bp->b_domain]);
1487 static struct bufqueue *
1488 bufqueue(struct buf *bp)
1491 switch (bp->b_qindex) {
1494 case QUEUE_SENTINEL:
1499 return (&bufdomain(bp)->bd_dirtyq);
1501 return (&bufdomain(bp)->bd_subq[bp->b_subqueue]);
1505 panic("bufqueue(%p): Unhandled type %d\n", bp, bp->b_qindex);
1509 * Return the locked bufqueue that bp is a member of.
1511 static struct bufqueue *
1512 bufqueue_acquire(struct buf *bp)
1514 struct bufqueue *bq, *nbq;
1517 * bp can be pushed from a per-cpu queue to the
1518 * cleanq while we're waiting on the lock. Retry
1519 * if the queues don't match.
1537 * Insert the buffer into the appropriate free list. Requires a
1538 * locked buffer on entry and buffer is unlocked before return.
1541 binsfree(struct buf *bp, int qindex)
1543 struct bufdomain *bd;
1544 struct bufqueue *bq;
1546 KASSERT(qindex == QUEUE_CLEAN || qindex == QUEUE_DIRTY,
1547 ("binsfree: Invalid qindex %d", qindex));
1548 BUF_ASSERT_XLOCKED(bp);
1551 * Handle delayed bremfree() processing.
1553 if (bp->b_flags & B_REMFREE) {
1554 if (bp->b_qindex == qindex) {
1555 bp->b_flags |= B_REUSE;
1556 bp->b_flags &= ~B_REMFREE;
1560 bq = bufqueue_acquire(bp);
1565 if (qindex == QUEUE_CLEAN) {
1566 if (bd->bd_lim != 0)
1567 bq = &bd->bd_subq[PCPU_GET(cpuid)];
1571 bq = &bd->bd_dirtyq;
1572 bq_insert(bq, bp, true);
1578 * Free a buffer to the buf zone once it no longer has valid contents.
1581 buf_free(struct buf *bp)
1584 if (bp->b_flags & B_REMFREE)
1586 if (bp->b_vflags & BV_BKGRDINPROG)
1587 panic("losing buffer 1");
1588 if (bp->b_rcred != NOCRED) {
1589 crfree(bp->b_rcred);
1590 bp->b_rcred = NOCRED;
1592 if (bp->b_wcred != NOCRED) {
1593 crfree(bp->b_wcred);
1594 bp->b_wcred = NOCRED;
1596 if (!LIST_EMPTY(&bp->b_dep))
1599 atomic_add_int(&bufdomain(bp)->bd_freebuffers, 1);
1600 MPASS((bp->b_flags & B_MAXPHYS) == 0);
1602 uma_zfree(buf_zone, bp);
1608 * Import bufs into the uma cache from the buf list. The system still
1609 * expects a static array of bufs and much of the synchronization
1610 * around bufs assumes type stable storage. As a result, UMA is used
1611 * only as a per-cpu cache of bufs still maintained on a global list.
1614 buf_import(void *arg, void **store, int cnt, int domain, int flags)
1620 for (i = 0; i < cnt; i++) {
1621 bp = TAILQ_FIRST(&bqempty.bq_queue);
1624 bq_remove(&bqempty, bp);
1627 BQ_UNLOCK(&bqempty);
1635 * Release bufs from the uma cache back to the buffer queues.
1638 buf_release(void *arg, void **store, int cnt)
1640 struct bufqueue *bq;
1646 for (i = 0; i < cnt; i++) {
1648 /* Inline bq_insert() to batch locking. */
1649 TAILQ_INSERT_TAIL(&bq->bq_queue, bp, b_freelist);
1650 bp->b_flags &= ~(B_AGE | B_REUSE);
1652 bp->b_qindex = bq->bq_index;
1660 * Allocate an empty buffer header.
1663 buf_alloc(struct bufdomain *bd)
1666 int freebufs, error;
1669 * We can only run out of bufs in the buf zone if the average buf
1670 * is less than BKVASIZE. In this case the actual wait/block will
1671 * come from buf_reycle() failing to flush one of these small bufs.
1674 freebufs = atomic_fetchadd_int(&bd->bd_freebuffers, -1);
1676 bp = uma_zalloc(buf_zone, M_NOWAIT);
1678 atomic_add_int(&bd->bd_freebuffers, 1);
1679 bufspace_daemon_wakeup(bd);
1680 counter_u64_add(numbufallocfails, 1);
1684 * Wake-up the bufspace daemon on transition below threshold.
1686 if (freebufs == bd->bd_lofreebuffers)
1687 bufspace_daemon_wakeup(bd);
1689 error = BUF_LOCK(bp, LK_EXCLUSIVE, NULL);
1690 KASSERT(error == 0, ("%s: BUF_LOCK on free buf %p: %d.", __func__, bp,
1694 KASSERT(bp->b_vp == NULL,
1695 ("bp: %p still has vnode %p.", bp, bp->b_vp));
1696 KASSERT((bp->b_flags & (B_DELWRI | B_NOREUSE)) == 0,
1697 ("invalid buffer %p flags %#x", bp, bp->b_flags));
1698 KASSERT((bp->b_xflags & (BX_VNCLEAN|BX_VNDIRTY)) == 0,
1699 ("bp: %p still on a buffer list. xflags %X", bp, bp->b_xflags));
1700 KASSERT(bp->b_npages == 0,
1701 ("bp: %p still has %d vm pages\n", bp, bp->b_npages));
1702 KASSERT(bp->b_kvasize == 0, ("bp: %p still has kva\n", bp));
1703 KASSERT(bp->b_bufsize == 0, ("bp: %p still has bufspace\n", bp));
1704 MPASS((bp->b_flags & B_MAXPHYS) == 0);
1706 bp->b_domain = BD_DOMAIN(bd);
1712 bp->b_blkno = bp->b_lblkno = 0;
1713 bp->b_offset = NOOFFSET;
1719 bp->b_dirtyoff = bp->b_dirtyend = 0;
1720 bp->b_bufobj = NULL;
1721 bp->b_data = bp->b_kvabase = unmapped_buf;
1722 bp->b_fsprivate1 = NULL;
1723 bp->b_fsprivate2 = NULL;
1724 bp->b_fsprivate3 = NULL;
1725 LIST_INIT(&bp->b_dep);
1733 * Free a buffer from the given bufqueue. kva controls whether the
1734 * freed buf must own some kva resources. This is used for
1738 buf_recycle(struct bufdomain *bd, bool kva)
1740 struct bufqueue *bq;
1741 struct buf *bp, *nbp;
1744 counter_u64_add(bufdefragcnt, 1);
1748 KASSERT(BQ_LOCKPTR(bq) == BD_LOCKPTR(bd),
1749 ("buf_recycle: Locks don't match"));
1750 nbp = TAILQ_FIRST(&bq->bq_queue);
1753 * Run scan, possibly freeing data and/or kva mappings on the fly
1756 while ((bp = nbp) != NULL) {
1758 * Calculate next bp (we can only use it if we do not
1759 * release the bqlock).
1761 nbp = TAILQ_NEXT(bp, b_freelist);
1764 * If we are defragging then we need a buffer with
1765 * some kva to reclaim.
1767 if (kva && bp->b_kvasize == 0)
1770 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0)
1774 * Implement a second chance algorithm for frequently
1777 if ((bp->b_flags & B_REUSE) != 0) {
1778 TAILQ_REMOVE(&bq->bq_queue, bp, b_freelist);
1779 TAILQ_INSERT_TAIL(&bq->bq_queue, bp, b_freelist);
1780 bp->b_flags &= ~B_REUSE;
1786 * Skip buffers with background writes in progress.
1788 if ((bp->b_vflags & BV_BKGRDINPROG) != 0) {
1793 KASSERT(bp->b_qindex == QUEUE_CLEAN,
1794 ("buf_recycle: inconsistent queue %d bp %p",
1796 KASSERT(bp->b_domain == BD_DOMAIN(bd),
1797 ("getnewbuf: queue domain %d doesn't match request %d",
1798 bp->b_domain, (int)BD_DOMAIN(bd)));
1800 * NOTE: nbp is now entirely invalid. We can only restart
1801 * the scan from this point on.
1807 * Requeue the background write buffer with error and
1810 if ((bp->b_vflags & BV_BKGRDERR) != 0) {
1813 nbp = TAILQ_FIRST(&bq->bq_queue);
1816 bp->b_flags |= B_INVAL;
1829 * Mark the buffer for removal from the appropriate free list.
1833 bremfree(struct buf *bp)
1836 CTR3(KTR_BUF, "bremfree(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
1837 KASSERT((bp->b_flags & B_REMFREE) == 0,
1838 ("bremfree: buffer %p already marked for delayed removal.", bp));
1839 KASSERT(bp->b_qindex != QUEUE_NONE,
1840 ("bremfree: buffer %p not on a queue.", bp));
1841 BUF_ASSERT_XLOCKED(bp);
1843 bp->b_flags |= B_REMFREE;
1849 * Force an immediate removal from a free list. Used only in nfs when
1850 * it abuses the b_freelist pointer.
1853 bremfreef(struct buf *bp)
1855 struct bufqueue *bq;
1857 bq = bufqueue_acquire(bp);
1863 bq_init(struct bufqueue *bq, int qindex, int subqueue, const char *lockname)
1866 mtx_init(&bq->bq_lock, lockname, NULL, MTX_DEF);
1867 TAILQ_INIT(&bq->bq_queue);
1869 bq->bq_index = qindex;
1870 bq->bq_subqueue = subqueue;
1874 bd_init(struct bufdomain *bd)
1878 bd->bd_cleanq = &bd->bd_subq[mp_maxid + 1];
1879 bq_init(bd->bd_cleanq, QUEUE_CLEAN, mp_maxid + 1, "bufq clean lock");
1880 bq_init(&bd->bd_dirtyq, QUEUE_DIRTY, -1, "bufq dirty lock");
1881 for (i = 0; i <= mp_maxid; i++)
1882 bq_init(&bd->bd_subq[i], QUEUE_CLEAN, i,
1883 "bufq clean subqueue lock");
1884 mtx_init(&bd->bd_run_lock, "bufspace daemon run lock", NULL, MTX_DEF);
1890 * Removes a buffer from the free list, must be called with the
1891 * correct qlock held.
1894 bq_remove(struct bufqueue *bq, struct buf *bp)
1897 CTR3(KTR_BUF, "bq_remove(%p) vp %p flags %X",
1898 bp, bp->b_vp, bp->b_flags);
1899 KASSERT(bp->b_qindex != QUEUE_NONE,
1900 ("bq_remove: buffer %p not on a queue.", bp));
1901 KASSERT(bufqueue(bp) == bq,
1902 ("bq_remove: Remove buffer %p from wrong queue.", bp));
1904 BQ_ASSERT_LOCKED(bq);
1905 if (bp->b_qindex != QUEUE_EMPTY) {
1906 BUF_ASSERT_XLOCKED(bp);
1908 KASSERT(bq->bq_len >= 1,
1909 ("queue %d underflow", bp->b_qindex));
1910 TAILQ_REMOVE(&bq->bq_queue, bp, b_freelist);
1912 bp->b_qindex = QUEUE_NONE;
1913 bp->b_flags &= ~(B_REMFREE | B_REUSE);
1917 bd_flush(struct bufdomain *bd, struct bufqueue *bq)
1921 BQ_ASSERT_LOCKED(bq);
1922 if (bq != bd->bd_cleanq) {
1924 while ((bp = TAILQ_FIRST(&bq->bq_queue)) != NULL) {
1925 TAILQ_REMOVE(&bq->bq_queue, bp, b_freelist);
1926 TAILQ_INSERT_TAIL(&bd->bd_cleanq->bq_queue, bp,
1928 bp->b_subqueue = bd->bd_cleanq->bq_subqueue;
1930 bd->bd_cleanq->bq_len += bq->bq_len;
1933 if (bd->bd_wanted) {
1935 wakeup(&bd->bd_wanted);
1937 if (bq != bd->bd_cleanq)
1942 bd_flushall(struct bufdomain *bd)
1944 struct bufqueue *bq;
1948 if (bd->bd_lim == 0)
1951 for (i = 0; i <= mp_maxid; i++) {
1952 bq = &bd->bd_subq[i];
1953 if (bq->bq_len == 0)
1965 bq_insert(struct bufqueue *bq, struct buf *bp, bool unlock)
1967 struct bufdomain *bd;
1969 if (bp->b_qindex != QUEUE_NONE)
1970 panic("bq_insert: free buffer %p onto another queue?", bp);
1973 if (bp->b_flags & B_AGE) {
1974 /* Place this buf directly on the real queue. */
1975 if (bq->bq_index == QUEUE_CLEAN)
1978 TAILQ_INSERT_HEAD(&bq->bq_queue, bp, b_freelist);
1981 TAILQ_INSERT_TAIL(&bq->bq_queue, bp, b_freelist);
1983 bp->b_flags &= ~(B_AGE | B_REUSE);
1985 bp->b_qindex = bq->bq_index;
1986 bp->b_subqueue = bq->bq_subqueue;
1989 * Unlock before we notify so that we don't wakeup a waiter that
1990 * fails a trylock on the buf and sleeps again.
1995 if (bp->b_qindex == QUEUE_CLEAN) {
1997 * Flush the per-cpu queue and notify any waiters.
1999 if (bd->bd_wanted || (bq != bd->bd_cleanq &&
2000 bq->bq_len >= bd->bd_lim))
2009 * Free the kva allocation for a buffer.
2013 bufkva_free(struct buf *bp)
2017 if (bp->b_kvasize == 0) {
2018 KASSERT(bp->b_kvabase == unmapped_buf &&
2019 bp->b_data == unmapped_buf,
2020 ("Leaked KVA space on %p", bp));
2021 } else if (buf_mapped(bp))
2022 BUF_CHECK_MAPPED(bp);
2024 BUF_CHECK_UNMAPPED(bp);
2026 if (bp->b_kvasize == 0)
2029 vmem_free(buffer_arena, (vm_offset_t)bp->b_kvabase, bp->b_kvasize);
2030 counter_u64_add(bufkvaspace, -bp->b_kvasize);
2031 counter_u64_add(buffreekvacnt, 1);
2032 bp->b_data = bp->b_kvabase = unmapped_buf;
2039 * Allocate the buffer KVA and set b_kvasize and b_kvabase.
2042 bufkva_alloc(struct buf *bp, int maxsize, int gbflags)
2047 KASSERT((gbflags & GB_UNMAPPED) == 0 || (gbflags & GB_KVAALLOC) != 0,
2048 ("Invalid gbflags 0x%x in %s", gbflags, __func__));
2049 MPASS((bp->b_flags & B_MAXPHYS) == 0);
2050 KASSERT(maxsize <= maxbcachebuf,
2051 ("bufkva_alloc kva too large %d %u", maxsize, maxbcachebuf));
2056 error = vmem_alloc(buffer_arena, maxsize, M_BESTFIT | M_NOWAIT, &addr);
2059 * Buffer map is too fragmented. Request the caller
2060 * to defragment the map.
2064 bp->b_kvabase = (caddr_t)addr;
2065 bp->b_kvasize = maxsize;
2066 counter_u64_add(bufkvaspace, bp->b_kvasize);
2067 if ((gbflags & GB_UNMAPPED) != 0) {
2068 bp->b_data = unmapped_buf;
2069 BUF_CHECK_UNMAPPED(bp);
2071 bp->b_data = bp->b_kvabase;
2072 BUF_CHECK_MAPPED(bp);
2080 * Reclaim buffer kva by freeing buffers holding kva. This is a vmem
2081 * callback that fires to avoid returning failure.
2084 bufkva_reclaim(vmem_t *vmem, int flags)
2091 for (i = 0; i < 5; i++) {
2092 for (q = 0; q < buf_domains; q++)
2093 if (buf_recycle(&bdomain[q], true) != 0)
2102 * Attempt to initiate asynchronous I/O on read-ahead blocks. We must
2103 * clear BIO_ERROR and B_INVAL prior to initiating I/O . If B_CACHE is set,
2104 * the buffer is valid and we do not have to do anything.
2107 breada(struct vnode * vp, daddr_t * rablkno, int * rabsize, int cnt,
2108 struct ucred * cred, int flags, void (*ckhashfunc)(struct buf *))
2116 for (i = 0; i < cnt; i++, rablkno++, rabsize++) {
2117 if (inmem(vp, *rablkno))
2119 rabp = getblk(vp, *rablkno, *rabsize, 0, 0, 0);
2120 if ((rabp->b_flags & B_CACHE) != 0) {
2127 racct_add_buf(curproc, rabp, 0);
2128 PROC_UNLOCK(curproc);
2131 td->td_ru.ru_inblock++;
2132 rabp->b_flags |= B_ASYNC;
2133 rabp->b_flags &= ~B_INVAL;
2134 if ((flags & GB_CKHASH) != 0) {
2135 rabp->b_flags |= B_CKHASH;
2136 rabp->b_ckhashcalc = ckhashfunc;
2138 rabp->b_ioflags &= ~BIO_ERROR;
2139 rabp->b_iocmd = BIO_READ;
2140 if (rabp->b_rcred == NOCRED && cred != NOCRED)
2141 rabp->b_rcred = crhold(cred);
2142 vfs_busy_pages(rabp, 0);
2144 rabp->b_iooffset = dbtob(rabp->b_blkno);
2150 * Entry point for bread() and breadn() via #defines in sys/buf.h.
2152 * Get a buffer with the specified data. Look in the cache first. We
2153 * must clear BIO_ERROR and B_INVAL prior to initiating I/O. If B_CACHE
2154 * is set, the buffer is valid and we do not have to do anything, see
2155 * getblk(). Also starts asynchronous I/O on read-ahead blocks.
2157 * Always return a NULL buffer pointer (in bpp) when returning an error.
2159 * The blkno parameter is the logical block being requested. Normally
2160 * the mapping of logical block number to disk block address is done
2161 * by calling VOP_BMAP(). However, if the mapping is already known, the
2162 * disk block address can be passed using the dblkno parameter. If the
2163 * disk block address is not known, then the same value should be passed
2164 * for blkno and dblkno.
2167 breadn_flags(struct vnode *vp, daddr_t blkno, daddr_t dblkno, int size,
2168 daddr_t *rablkno, int *rabsize, int cnt, struct ucred *cred, int flags,
2169 void (*ckhashfunc)(struct buf *), struct buf **bpp)
2173 int error, readwait, rv;
2175 CTR3(KTR_BUF, "breadn(%p, %jd, %d)", vp, blkno, size);
2178 * Can only return NULL if GB_LOCK_NOWAIT or GB_SPARSE flags
2181 error = getblkx(vp, blkno, dblkno, size, 0, 0, flags, &bp);
2186 KASSERT(blkno == bp->b_lblkno,
2187 ("getblkx returned buffer for blkno %jd instead of blkno %jd",
2188 (intmax_t)bp->b_lblkno, (intmax_t)blkno));
2189 flags &= ~GB_NOSPARSE;
2193 * If not found in cache, do some I/O
2196 if ((bp->b_flags & B_CACHE) == 0) {
2199 PROC_LOCK(td->td_proc);
2200 racct_add_buf(td->td_proc, bp, 0);
2201 PROC_UNLOCK(td->td_proc);
2204 td->td_ru.ru_inblock++;
2205 bp->b_iocmd = BIO_READ;
2206 bp->b_flags &= ~B_INVAL;
2207 if ((flags & GB_CKHASH) != 0) {
2208 bp->b_flags |= B_CKHASH;
2209 bp->b_ckhashcalc = ckhashfunc;
2211 if ((flags & GB_CVTENXIO) != 0)
2212 bp->b_xflags |= BX_CVTENXIO;
2213 bp->b_ioflags &= ~BIO_ERROR;
2214 if (bp->b_rcred == NOCRED && cred != NOCRED)
2215 bp->b_rcred = crhold(cred);
2216 vfs_busy_pages(bp, 0);
2217 bp->b_iooffset = dbtob(bp->b_blkno);
2223 * Attempt to initiate asynchronous I/O on read-ahead blocks.
2225 breada(vp, rablkno, rabsize, cnt, cred, flags, ckhashfunc);
2239 * Write, release buffer on completion. (Done by iodone
2240 * if async). Do not bother writing anything if the buffer
2243 * Note that we set B_CACHE here, indicating that buffer is
2244 * fully valid and thus cacheable. This is true even of NFS
2245 * now so we set it generally. This could be set either here
2246 * or in biodone() since the I/O is synchronous. We put it
2250 bufwrite(struct buf *bp)
2257 CTR3(KTR_BUF, "bufwrite(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
2258 if ((bp->b_bufobj->bo_flag & BO_DEAD) != 0) {
2259 bp->b_flags |= B_INVAL | B_RELBUF;
2260 bp->b_flags &= ~B_CACHE;
2264 if (bp->b_flags & B_INVAL) {
2269 if (bp->b_flags & B_BARRIER)
2270 atomic_add_long(&barrierwrites, 1);
2272 oldflags = bp->b_flags;
2274 KASSERT(!(bp->b_vflags & BV_BKGRDINPROG),
2275 ("FFS background buffer should not get here %p", bp));
2279 vp_md = vp->v_vflag & VV_MD;
2284 * Mark the buffer clean. Increment the bufobj write count
2285 * before bundirty() call, to prevent other thread from seeing
2286 * empty dirty list and zero counter for writes in progress,
2287 * falsely indicating that the bufobj is clean.
2289 bufobj_wref(bp->b_bufobj);
2292 bp->b_flags &= ~B_DONE;
2293 bp->b_ioflags &= ~BIO_ERROR;
2294 bp->b_flags |= B_CACHE;
2295 bp->b_iocmd = BIO_WRITE;
2297 vfs_busy_pages(bp, 1);
2300 * Normal bwrites pipeline writes
2302 bp->b_runningbufspace = bp->b_bufsize;
2303 space = atomic_fetchadd_long(&runningbufspace, bp->b_runningbufspace);
2308 racct_add_buf(curproc, bp, 1);
2309 PROC_UNLOCK(curproc);
2312 curthread->td_ru.ru_oublock++;
2313 if (oldflags & B_ASYNC)
2315 bp->b_iooffset = dbtob(bp->b_blkno);
2316 buf_track(bp, __func__);
2319 if ((oldflags & B_ASYNC) == 0) {
2320 int rtval = bufwait(bp);
2323 } else if (space > hirunningspace) {
2325 * don't allow the async write to saturate the I/O
2326 * system. We will not deadlock here because
2327 * we are blocking waiting for I/O that is already in-progress
2328 * to complete. We do not block here if it is the update
2329 * or syncer daemon trying to clean up as that can lead
2332 if ((curthread->td_pflags & TDP_NORUNNINGBUF) == 0 && !vp_md)
2333 waitrunningbufspace();
2340 bufbdflush(struct bufobj *bo, struct buf *bp)
2343 struct bufdomain *bd;
2345 bd = &bdomain[bo->bo_domain];
2346 if (bo->bo_dirty.bv_cnt > bd->bd_dirtybufthresh + 10) {
2347 (void) VOP_FSYNC(bp->b_vp, MNT_NOWAIT, curthread);
2349 } else if (bo->bo_dirty.bv_cnt > bd->bd_dirtybufthresh) {
2352 * Try to find a buffer to flush.
2354 TAILQ_FOREACH(nbp, &bo->bo_dirty.bv_hd, b_bobufs) {
2355 if ((nbp->b_vflags & BV_BKGRDINPROG) ||
2357 LK_EXCLUSIVE | LK_NOWAIT, NULL))
2360 panic("bdwrite: found ourselves");
2362 /* Don't countdeps with the bo lock held. */
2363 if (buf_countdeps(nbp, 0)) {
2368 if (nbp->b_flags & B_CLUSTEROK) {
2369 vfs_bio_awrite(nbp);
2374 dirtybufferflushes++;
2383 * Delayed write. (Buffer is marked dirty). Do not bother writing
2384 * anything if the buffer is marked invalid.
2386 * Note that since the buffer must be completely valid, we can safely
2387 * set B_CACHE. In fact, we have to set B_CACHE here rather then in
2388 * biodone() in order to prevent getblk from writing the buffer
2389 * out synchronously.
2392 bdwrite(struct buf *bp)
2394 struct thread *td = curthread;
2398 CTR3(KTR_BUF, "bdwrite(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
2399 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp));
2400 KASSERT((bp->b_flags & B_BARRIER) == 0,
2401 ("Barrier request in delayed write %p", bp));
2403 if (bp->b_flags & B_INVAL) {
2409 * If we have too many dirty buffers, don't create any more.
2410 * If we are wildly over our limit, then force a complete
2411 * cleanup. Otherwise, just keep the situation from getting
2412 * out of control. Note that we have to avoid a recursive
2413 * disaster and not try to clean up after our own cleanup!
2417 if ((td->td_pflags & (TDP_COWINPROGRESS|TDP_INBDFLUSH)) == 0) {
2418 td->td_pflags |= TDP_INBDFLUSH;
2420 td->td_pflags &= ~TDP_INBDFLUSH;
2426 * Set B_CACHE, indicating that the buffer is fully valid. This is
2427 * true even of NFS now.
2429 bp->b_flags |= B_CACHE;
2432 * This bmap keeps the system from needing to do the bmap later,
2433 * perhaps when the system is attempting to do a sync. Since it
2434 * is likely that the indirect block -- or whatever other datastructure
2435 * that the filesystem needs is still in memory now, it is a good
2436 * thing to do this. Note also, that if the pageout daemon is
2437 * requesting a sync -- there might not be enough memory to do
2438 * the bmap then... So, this is important to do.
2440 if (vp->v_type != VCHR && bp->b_lblkno == bp->b_blkno) {
2441 VOP_BMAP(vp, bp->b_lblkno, NULL, &bp->b_blkno, NULL, NULL);
2444 buf_track(bp, __func__);
2447 * Set the *dirty* buffer range based upon the VM system dirty
2450 * Mark the buffer pages as clean. We need to do this here to
2451 * satisfy the vnode_pager and the pageout daemon, so that it
2452 * thinks that the pages have been "cleaned". Note that since
2453 * the pages are in a delayed write buffer -- the VFS layer
2454 * "will" see that the pages get written out on the next sync,
2455 * or perhaps the cluster will be completed.
2457 vfs_clean_pages_dirty_buf(bp);
2461 * note: we cannot initiate I/O from a bdwrite even if we wanted to,
2462 * due to the softdep code.
2469 * Turn buffer into delayed write request. We must clear BIO_READ and
2470 * B_RELBUF, and we must set B_DELWRI. We reassign the buffer to
2471 * itself to properly update it in the dirty/clean lists. We mark it
2472 * B_DONE to ensure that any asynchronization of the buffer properly
2473 * clears B_DONE ( else a panic will occur later ).
2475 * bdirty() is kinda like bdwrite() - we have to clear B_INVAL which
2476 * might have been set pre-getblk(). Unlike bwrite/bdwrite, bdirty()
2477 * should only be called if the buffer is known-good.
2479 * Since the buffer is not on a queue, we do not update the numfreebuffers
2482 * The buffer must be on QUEUE_NONE.
2485 bdirty(struct buf *bp)
2488 CTR3(KTR_BUF, "bdirty(%p) vp %p flags %X",
2489 bp, bp->b_vp, bp->b_flags);
2490 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp));
2491 KASSERT(bp->b_flags & B_REMFREE || bp->b_qindex == QUEUE_NONE,
2492 ("bdirty: buffer %p still on queue %d", bp, bp->b_qindex));
2493 bp->b_flags &= ~(B_RELBUF);
2494 bp->b_iocmd = BIO_WRITE;
2496 if ((bp->b_flags & B_DELWRI) == 0) {
2497 bp->b_flags |= /* XXX B_DONE | */ B_DELWRI;
2506 * Clear B_DELWRI for buffer.
2508 * Since the buffer is not on a queue, we do not update the numfreebuffers
2511 * The buffer must be on QUEUE_NONE.
2515 bundirty(struct buf *bp)
2518 CTR3(KTR_BUF, "bundirty(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
2519 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp));
2520 KASSERT(bp->b_flags & B_REMFREE || bp->b_qindex == QUEUE_NONE,
2521 ("bundirty: buffer %p still on queue %d", bp, bp->b_qindex));
2523 if (bp->b_flags & B_DELWRI) {
2524 bp->b_flags &= ~B_DELWRI;
2529 * Since it is now being written, we can clear its deferred write flag.
2531 bp->b_flags &= ~B_DEFERRED;
2537 * Asynchronous write. Start output on a buffer, but do not wait for
2538 * it to complete. The buffer is released when the output completes.
2540 * bwrite() ( or the VOP routine anyway ) is responsible for handling
2541 * B_INVAL buffers. Not us.
2544 bawrite(struct buf *bp)
2547 bp->b_flags |= B_ASYNC;
2554 * Asynchronous barrier write. Start output on a buffer, but do not
2555 * wait for it to complete. Place a write barrier after this write so
2556 * that this buffer and all buffers written before it are committed to
2557 * the disk before any buffers written after this write are committed
2558 * to the disk. The buffer is released when the output completes.
2561 babarrierwrite(struct buf *bp)
2564 bp->b_flags |= B_ASYNC | B_BARRIER;
2571 * Synchronous barrier write. Start output on a buffer and wait for
2572 * it to complete. Place a write barrier after this write so that
2573 * this buffer and all buffers written before it are committed to
2574 * the disk before any buffers written after this write are committed
2575 * to the disk. The buffer is released when the output completes.
2578 bbarrierwrite(struct buf *bp)
2581 bp->b_flags |= B_BARRIER;
2582 return (bwrite(bp));
2588 * Called prior to the locking of any vnodes when we are expecting to
2589 * write. We do not want to starve the buffer cache with too many
2590 * dirty buffers so we block here. By blocking prior to the locking
2591 * of any vnodes we attempt to avoid the situation where a locked vnode
2592 * prevents the various system daemons from flushing related buffers.
2598 if (buf_dirty_count_severe()) {
2599 mtx_lock(&bdirtylock);
2600 while (buf_dirty_count_severe()) {
2602 msleep(&bdirtywait, &bdirtylock, (PRIBIO + 4),
2605 mtx_unlock(&bdirtylock);
2610 * Return true if we have too many dirty buffers.
2613 buf_dirty_count_severe(void)
2616 return (!BIT_EMPTY(BUF_DOMAINS, &bdhidirty));
2622 * Release a busy buffer and, if requested, free its resources. The
2623 * buffer will be stashed in the appropriate bufqueue[] allowing it
2624 * to be accessed later as a cache entity or reused for other purposes.
2627 brelse(struct buf *bp)
2629 struct mount *v_mnt;
2633 * Many functions erroneously call brelse with a NULL bp under rare
2634 * error conditions. Simply return when called with a NULL bp.
2638 CTR3(KTR_BUF, "brelse(%p) vp %p flags %X",
2639 bp, bp->b_vp, bp->b_flags);
2640 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)),
2641 ("brelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp));
2642 KASSERT((bp->b_flags & B_VMIO) != 0 || (bp->b_flags & B_NOREUSE) == 0,
2643 ("brelse: non-VMIO buffer marked NOREUSE"));
2645 if (BUF_LOCKRECURSED(bp)) {
2647 * Do not process, in particular, do not handle the
2648 * B_INVAL/B_RELBUF and do not release to free list.
2654 if (bp->b_flags & B_MANAGED) {
2659 if (LIST_EMPTY(&bp->b_dep)) {
2660 bp->b_flags &= ~B_IOSTARTED;
2662 KASSERT((bp->b_flags & B_IOSTARTED) == 0,
2663 ("brelse: SU io not finished bp %p", bp));
2666 if ((bp->b_vflags & (BV_BKGRDINPROG | BV_BKGRDERR)) == BV_BKGRDERR) {
2667 BO_LOCK(bp->b_bufobj);
2668 bp->b_vflags &= ~BV_BKGRDERR;
2669 BO_UNLOCK(bp->b_bufobj);
2673 if (bp->b_iocmd == BIO_WRITE && (bp->b_ioflags & BIO_ERROR) &&
2674 (bp->b_flags & B_INVALONERR)) {
2676 * Forced invalidation of dirty buffer contents, to be used
2677 * after a failed write in the rare case that the loss of the
2678 * contents is acceptable. The buffer is invalidated and
2681 bp->b_flags |= B_INVAL | B_RELBUF | B_NOCACHE;
2682 bp->b_flags &= ~(B_ASYNC | B_CACHE);
2685 if (bp->b_iocmd == BIO_WRITE && (bp->b_ioflags & BIO_ERROR) &&
2686 (bp->b_error != ENXIO || !LIST_EMPTY(&bp->b_dep)) &&
2687 !(bp->b_flags & B_INVAL)) {
2689 * Failed write, redirty. All errors except ENXIO (which
2690 * means the device is gone) are treated as being
2693 * XXX Treating EIO as transient is not correct; the
2694 * contract with the local storage device drivers is that
2695 * they will only return EIO once the I/O is no longer
2696 * retriable. Network I/O also respects this through the
2697 * guarantees of TCP and/or the internal retries of NFS.
2698 * ENOMEM might be transient, but we also have no way of
2699 * knowing when its ok to retry/reschedule. In general,
2700 * this entire case should be made obsolete through better
2701 * error handling/recovery and resource scheduling.
2703 * Do this also for buffers that failed with ENXIO, but have
2704 * non-empty dependencies - the soft updates code might need
2705 * to access the buffer to untangle them.
2707 * Must clear BIO_ERROR to prevent pages from being scrapped.
2709 bp->b_ioflags &= ~BIO_ERROR;
2711 } else if ((bp->b_flags & (B_NOCACHE | B_INVAL)) ||
2712 (bp->b_ioflags & BIO_ERROR) || (bp->b_bufsize <= 0)) {
2714 * Either a failed read I/O, or we were asked to free or not
2715 * cache the buffer, or we failed to write to a device that's
2716 * no longer present.
2718 bp->b_flags |= B_INVAL;
2719 if (!LIST_EMPTY(&bp->b_dep))
2721 if (bp->b_flags & B_DELWRI)
2723 bp->b_flags &= ~(B_DELWRI | B_CACHE);
2724 if ((bp->b_flags & B_VMIO) == 0) {
2732 * We must clear B_RELBUF if B_DELWRI is set. If vfs_vmio_truncate()
2733 * is called with B_DELWRI set, the underlying pages may wind up
2734 * getting freed causing a previous write (bdwrite()) to get 'lost'
2735 * because pages associated with a B_DELWRI bp are marked clean.
2737 * We still allow the B_INVAL case to call vfs_vmio_truncate(), even
2738 * if B_DELWRI is set.
2740 if (bp->b_flags & B_DELWRI)
2741 bp->b_flags &= ~B_RELBUF;
2744 * VMIO buffer rundown. It is not very necessary to keep a VMIO buffer
2745 * constituted, not even NFS buffers now. Two flags effect this. If
2746 * B_INVAL, the struct buf is invalidated but the VM object is kept
2747 * around ( i.e. so it is trivial to reconstitute the buffer later ).
2749 * If BIO_ERROR or B_NOCACHE is set, pages in the VM object will be
2750 * invalidated. BIO_ERROR cannot be set for a failed write unless the
2751 * buffer is also B_INVAL because it hits the re-dirtying code above.
2753 * Normally we can do this whether a buffer is B_DELWRI or not. If
2754 * the buffer is an NFS buffer, it is tracking piecemeal writes or
2755 * the commit state and we cannot afford to lose the buffer. If the
2756 * buffer has a background write in progress, we need to keep it
2757 * around to prevent it from being reconstituted and starting a second
2761 v_mnt = bp->b_vp != NULL ? bp->b_vp->v_mount : NULL;
2763 if ((bp->b_flags & B_VMIO) && (bp->b_flags & B_NOCACHE ||
2764 (bp->b_ioflags & BIO_ERROR && bp->b_iocmd == BIO_READ)) &&
2765 (v_mnt == NULL || (v_mnt->mnt_vfc->vfc_flags & VFCF_NETWORK) == 0 ||
2766 vn_isdisk(bp->b_vp) || (bp->b_flags & B_DELWRI) == 0)) {
2767 vfs_vmio_invalidate(bp);
2771 if ((bp->b_flags & (B_INVAL | B_RELBUF)) != 0 ||
2772 (bp->b_flags & (B_DELWRI | B_NOREUSE)) == B_NOREUSE) {
2774 bp->b_flags &= ~B_NOREUSE;
2775 if (bp->b_vp != NULL)
2780 * If the buffer has junk contents signal it and eventually
2781 * clean up B_DELWRI and diassociate the vnode so that gbincore()
2784 if (bp->b_bufsize == 0 || (bp->b_ioflags & BIO_ERROR) != 0 ||
2785 (bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF)) != 0)
2786 bp->b_flags |= B_INVAL;
2787 if (bp->b_flags & B_INVAL) {
2788 if (bp->b_flags & B_DELWRI)
2794 buf_track(bp, __func__);
2796 /* buffers with no memory */
2797 if (bp->b_bufsize == 0) {
2801 /* buffers with junk contents */
2802 if (bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF) ||
2803 (bp->b_ioflags & BIO_ERROR)) {
2804 bp->b_xflags &= ~(BX_BKGRDWRITE | BX_ALTDATA);
2805 if (bp->b_vflags & BV_BKGRDINPROG)
2806 panic("losing buffer 2");
2807 qindex = QUEUE_CLEAN;
2808 bp->b_flags |= B_AGE;
2809 /* remaining buffers */
2810 } else if (bp->b_flags & B_DELWRI)
2811 qindex = QUEUE_DIRTY;
2813 qindex = QUEUE_CLEAN;
2815 if ((bp->b_flags & B_DELWRI) == 0 && (bp->b_xflags & BX_VNDIRTY))
2816 panic("brelse: not dirty");
2818 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_RELBUF | B_DIRECT);
2819 bp->b_xflags &= ~(BX_CVTENXIO);
2820 /* binsfree unlocks bp. */
2821 binsfree(bp, qindex);
2825 * Release a buffer back to the appropriate queue but do not try to free
2826 * it. The buffer is expected to be used again soon.
2828 * bqrelse() is used by bdwrite() to requeue a delayed write, and used by
2829 * biodone() to requeue an async I/O on completion. It is also used when
2830 * known good buffers need to be requeued but we think we may need the data
2833 * XXX we should be able to leave the B_RELBUF hint set on completion.
2836 bqrelse(struct buf *bp)
2840 CTR3(KTR_BUF, "bqrelse(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
2841 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)),
2842 ("bqrelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp));
2844 qindex = QUEUE_NONE;
2845 if (BUF_LOCKRECURSED(bp)) {
2846 /* do not release to free list */
2850 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF);
2851 bp->b_xflags &= ~(BX_CVTENXIO);
2853 if (LIST_EMPTY(&bp->b_dep)) {
2854 bp->b_flags &= ~B_IOSTARTED;
2856 KASSERT((bp->b_flags & B_IOSTARTED) == 0,
2857 ("bqrelse: SU io not finished bp %p", bp));
2860 if (bp->b_flags & B_MANAGED) {
2861 if (bp->b_flags & B_REMFREE)
2866 /* buffers with stale but valid contents */
2867 if ((bp->b_flags & B_DELWRI) != 0 || (bp->b_vflags & (BV_BKGRDINPROG |
2868 BV_BKGRDERR)) == BV_BKGRDERR) {
2869 BO_LOCK(bp->b_bufobj);
2870 bp->b_vflags &= ~BV_BKGRDERR;
2871 BO_UNLOCK(bp->b_bufobj);
2872 qindex = QUEUE_DIRTY;
2874 if ((bp->b_flags & B_DELWRI) == 0 &&
2875 (bp->b_xflags & BX_VNDIRTY))
2876 panic("bqrelse: not dirty");
2877 if ((bp->b_flags & B_NOREUSE) != 0) {
2881 qindex = QUEUE_CLEAN;
2883 buf_track(bp, __func__);
2884 /* binsfree unlocks bp. */
2885 binsfree(bp, qindex);
2889 buf_track(bp, __func__);
2895 * Complete I/O to a VMIO backed page. Validate the pages as appropriate,
2896 * restore bogus pages.
2899 vfs_vmio_iodone(struct buf *bp)
2904 struct vnode *vp __unused;
2905 int i, iosize, resid;
2908 obj = bp->b_bufobj->bo_object;
2909 KASSERT(blockcount_read(&obj->paging_in_progress) >= bp->b_npages,
2910 ("vfs_vmio_iodone: paging in progress(%d) < b_npages(%d)",
2911 blockcount_read(&obj->paging_in_progress), bp->b_npages));
2914 VNPASS(vp->v_holdcnt > 0, vp);
2915 VNPASS(vp->v_object != NULL, vp);
2917 foff = bp->b_offset;
2918 KASSERT(bp->b_offset != NOOFFSET,
2919 ("vfs_vmio_iodone: bp %p has no buffer offset", bp));
2922 iosize = bp->b_bcount - bp->b_resid;
2923 for (i = 0; i < bp->b_npages; i++) {
2924 resid = ((foff + PAGE_SIZE) & ~(off_t)PAGE_MASK) - foff;
2929 * cleanup bogus pages, restoring the originals
2932 if (m == bogus_page) {
2934 m = vm_page_relookup(obj, OFF_TO_IDX(foff));
2936 panic("biodone: page disappeared!");
2938 } else if ((bp->b_iocmd == BIO_READ) && resid > 0) {
2940 * In the write case, the valid and clean bits are
2941 * already changed correctly ( see bdwrite() ), so we
2942 * only need to do this here in the read case.
2944 KASSERT((m->dirty & vm_page_bits(foff & PAGE_MASK,
2945 resid)) == 0, ("vfs_vmio_iodone: page %p "
2946 "has unexpected dirty bits", m));
2947 vfs_page_set_valid(bp, foff, m);
2949 KASSERT(OFF_TO_IDX(foff) == m->pindex,
2950 ("vfs_vmio_iodone: foff(%jd)/pindex(%ju) mismatch",
2951 (intmax_t)foff, (uintmax_t)m->pindex));
2954 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK;
2957 vm_object_pip_wakeupn(obj, bp->b_npages);
2958 if (bogus && buf_mapped(bp)) {
2959 BUF_CHECK_MAPPED(bp);
2960 pmap_qenter(trunc_page((vm_offset_t)bp->b_data),
2961 bp->b_pages, bp->b_npages);
2966 * Perform page invalidation when a buffer is released. The fully invalid
2967 * pages will be reclaimed later in vfs_vmio_truncate().
2970 vfs_vmio_invalidate(struct buf *bp)
2974 int flags, i, resid, poffset, presid;
2976 if (buf_mapped(bp)) {
2977 BUF_CHECK_MAPPED(bp);
2978 pmap_qremove(trunc_page((vm_offset_t)bp->b_data), bp->b_npages);
2980 BUF_CHECK_UNMAPPED(bp);
2982 * Get the base offset and length of the buffer. Note that
2983 * in the VMIO case if the buffer block size is not
2984 * page-aligned then b_data pointer may not be page-aligned.
2985 * But our b_pages[] array *IS* page aligned.
2987 * block sizes less then DEV_BSIZE (usually 512) are not
2988 * supported due to the page granularity bits (m->valid,
2989 * m->dirty, etc...).
2991 * See man buf(9) for more information
2993 flags = (bp->b_flags & B_NOREUSE) != 0 ? VPR_NOREUSE : 0;
2994 obj = bp->b_bufobj->bo_object;
2995 resid = bp->b_bufsize;
2996 poffset = bp->b_offset & PAGE_MASK;
2997 VM_OBJECT_WLOCK(obj);
2998 for (i = 0; i < bp->b_npages; i++) {
3000 if (m == bogus_page)
3001 panic("vfs_vmio_invalidate: Unexpected bogus page.");
3002 bp->b_pages[i] = NULL;
3004 presid = resid > (PAGE_SIZE - poffset) ?
3005 (PAGE_SIZE - poffset) : resid;
3006 KASSERT(presid >= 0, ("brelse: extra page"));
3007 vm_page_busy_acquire(m, VM_ALLOC_SBUSY);
3008 if (pmap_page_wired_mappings(m) == 0)
3009 vm_page_set_invalid(m, poffset, presid);
3011 vm_page_release_locked(m, flags);
3015 VM_OBJECT_WUNLOCK(obj);
3020 * Page-granular truncation of an existing VMIO buffer.
3023 vfs_vmio_truncate(struct buf *bp, int desiredpages)
3029 if (bp->b_npages == desiredpages)
3032 if (buf_mapped(bp)) {
3033 BUF_CHECK_MAPPED(bp);
3034 pmap_qremove((vm_offset_t)trunc_page((vm_offset_t)bp->b_data) +
3035 (desiredpages << PAGE_SHIFT), bp->b_npages - desiredpages);
3037 BUF_CHECK_UNMAPPED(bp);
3040 * The object lock is needed only if we will attempt to free pages.
3042 flags = (bp->b_flags & B_NOREUSE) != 0 ? VPR_NOREUSE : 0;
3043 if ((bp->b_flags & B_DIRECT) != 0) {
3044 flags |= VPR_TRYFREE;
3045 obj = bp->b_bufobj->bo_object;
3046 VM_OBJECT_WLOCK(obj);
3050 for (i = desiredpages; i < bp->b_npages; i++) {
3052 KASSERT(m != bogus_page, ("allocbuf: bogus page found"));
3053 bp->b_pages[i] = NULL;
3055 vm_page_release_locked(m, flags);
3057 vm_page_release(m, flags);
3060 VM_OBJECT_WUNLOCK(obj);
3061 bp->b_npages = desiredpages;
3065 * Byte granular extension of VMIO buffers.
3068 vfs_vmio_extend(struct buf *bp, int desiredpages, int size)
3071 * We are growing the buffer, possibly in a
3072 * byte-granular fashion.
3080 * Step 1, bring in the VM pages from the object, allocating
3081 * them if necessary. We must clear B_CACHE if these pages
3082 * are not valid for the range covered by the buffer.
3084 obj = bp->b_bufobj->bo_object;
3085 if (bp->b_npages < desiredpages) {
3086 KASSERT(desiredpages <= atop(maxbcachebuf),
3087 ("vfs_vmio_extend past maxbcachebuf %p %d %u",
3088 bp, desiredpages, maxbcachebuf));
3091 * We must allocate system pages since blocking
3092 * here could interfere with paging I/O, no
3093 * matter which process we are.
3095 * Only exclusive busy can be tested here.
3096 * Blocking on shared busy might lead to
3097 * deadlocks once allocbuf() is called after
3098 * pages are vfs_busy_pages().
3100 (void)vm_page_grab_pages_unlocked(obj,
3101 OFF_TO_IDX(bp->b_offset) + bp->b_npages,
3102 VM_ALLOC_SYSTEM | VM_ALLOC_IGN_SBUSY |
3103 VM_ALLOC_NOBUSY | VM_ALLOC_WIRED,
3104 &bp->b_pages[bp->b_npages], desiredpages - bp->b_npages);
3105 bp->b_npages = desiredpages;
3109 * Step 2. We've loaded the pages into the buffer,
3110 * we have to figure out if we can still have B_CACHE
3111 * set. Note that B_CACHE is set according to the
3112 * byte-granular range ( bcount and size ), not the
3113 * aligned range ( newbsize ).
3115 * The VM test is against m->valid, which is DEV_BSIZE
3116 * aligned. Needless to say, the validity of the data
3117 * needs to also be DEV_BSIZE aligned. Note that this
3118 * fails with NFS if the server or some other client
3119 * extends the file's EOF. If our buffer is resized,
3120 * B_CACHE may remain set! XXX
3122 toff = bp->b_bcount;
3123 tinc = PAGE_SIZE - ((bp->b_offset + toff) & PAGE_MASK);
3124 while ((bp->b_flags & B_CACHE) && toff < size) {
3127 if (tinc > (size - toff))
3129 pi = ((bp->b_offset & PAGE_MASK) + toff) >> PAGE_SHIFT;
3130 m = bp->b_pages[pi];
3131 vfs_buf_test_cache(bp, bp->b_offset, toff, tinc, m);
3137 * Step 3, fixup the KVA pmap.
3142 BUF_CHECK_UNMAPPED(bp);
3146 * Check to see if a block at a particular lbn is available for a clustered
3150 vfs_bio_clcheck(struct vnode *vp, int size, daddr_t lblkno, daddr_t blkno)
3157 /* If the buf isn't in core skip it */
3158 if ((bpa = gbincore(&vp->v_bufobj, lblkno)) == NULL)
3161 /* If the buf is busy we don't want to wait for it */
3162 if (BUF_LOCK(bpa, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0)
3165 /* Only cluster with valid clusterable delayed write buffers */
3166 if ((bpa->b_flags & (B_DELWRI | B_CLUSTEROK | B_INVAL)) !=
3167 (B_DELWRI | B_CLUSTEROK))
3170 if (bpa->b_bufsize != size)
3174 * Check to see if it is in the expected place on disk and that the
3175 * block has been mapped.
3177 if ((bpa->b_blkno != bpa->b_lblkno) && (bpa->b_blkno == blkno))
3187 * Implement clustered async writes for clearing out B_DELWRI buffers.
3188 * This is much better then the old way of writing only one buffer at
3189 * a time. Note that we may not be presented with the buffers in the
3190 * correct order, so we search for the cluster in both directions.
3193 vfs_bio_awrite(struct buf *bp)
3198 daddr_t lblkno = bp->b_lblkno;
3199 struct vnode *vp = bp->b_vp;
3207 gbflags = (bp->b_data == unmapped_buf) ? GB_UNMAPPED : 0;
3209 * right now we support clustered writing only to regular files. If
3210 * we find a clusterable block we could be in the middle of a cluster
3211 * rather then at the beginning.
3213 if ((vp->v_type == VREG) &&
3214 (vp->v_mount != 0) && /* Only on nodes that have the size info */
3215 (bp->b_flags & (B_CLUSTEROK | B_INVAL)) == B_CLUSTEROK) {
3216 size = vp->v_mount->mnt_stat.f_iosize;
3217 maxcl = maxphys / size;
3220 for (i = 1; i < maxcl; i++)
3221 if (vfs_bio_clcheck(vp, size, lblkno + i,
3222 bp->b_blkno + ((i * size) >> DEV_BSHIFT)) == 0)
3225 for (j = 1; i + j <= maxcl && j <= lblkno; j++)
3226 if (vfs_bio_clcheck(vp, size, lblkno - j,
3227 bp->b_blkno - ((j * size) >> DEV_BSHIFT)) == 0)
3233 * this is a possible cluster write
3237 nwritten = cluster_wbuild(vp, size, lblkno - j, ncl,
3243 bp->b_flags |= B_ASYNC;
3245 * default (old) behavior, writing out only one block
3247 * XXX returns b_bufsize instead of b_bcount for nwritten?
3249 nwritten = bp->b_bufsize;
3258 * Allocate KVA for an empty buf header according to gbflags.
3261 getnewbuf_kva(struct buf *bp, int gbflags, int maxsize)
3264 if ((gbflags & (GB_UNMAPPED | GB_KVAALLOC)) != GB_UNMAPPED) {
3266 * In order to keep fragmentation sane we only allocate kva
3267 * in BKVASIZE chunks. XXX with vmem we can do page size.
3269 maxsize = (maxsize + BKVAMASK) & ~BKVAMASK;
3271 if (maxsize != bp->b_kvasize &&
3272 bufkva_alloc(bp, maxsize, gbflags))
3281 * Find and initialize a new buffer header, freeing up existing buffers
3282 * in the bufqueues as necessary. The new buffer is returned locked.
3285 * We have insufficient buffer headers
3286 * We have insufficient buffer space
3287 * buffer_arena is too fragmented ( space reservation fails )
3288 * If we have to flush dirty buffers ( but we try to avoid this )
3290 * The caller is responsible for releasing the reserved bufspace after
3291 * allocbuf() is called.
3294 getnewbuf(struct vnode *vp, int slpflag, int slptimeo, int maxsize, int gbflags)
3296 struct bufdomain *bd;
3298 bool metadata, reserved;
3301 KASSERT((gbflags & (GB_UNMAPPED | GB_KVAALLOC)) != GB_KVAALLOC,
3302 ("GB_KVAALLOC only makes sense with GB_UNMAPPED"));
3303 if (!unmapped_buf_allowed)
3304 gbflags &= ~(GB_UNMAPPED | GB_KVAALLOC);
3306 if (vp == NULL || (vp->v_vflag & (VV_MD | VV_SYSTEM)) != 0 ||
3314 bd = &bdomain[vp->v_bufobj.bo_domain];
3316 counter_u64_add(getnewbufcalls, 1);
3319 if (reserved == false &&
3320 bufspace_reserve(bd, maxsize, metadata) != 0) {
3321 counter_u64_add(getnewbufrestarts, 1);
3325 if ((bp = buf_alloc(bd)) == NULL) {
3326 counter_u64_add(getnewbufrestarts, 1);
3329 if (getnewbuf_kva(bp, gbflags, maxsize) == 0)
3332 } while (buf_recycle(bd, false) == 0);
3335 bufspace_release(bd, maxsize);
3337 bp->b_flags |= B_INVAL;
3340 bufspace_wait(bd, vp, gbflags, slpflag, slptimeo);
3348 * buffer flushing daemon. Buffers are normally flushed by the
3349 * update daemon but if it cannot keep up this process starts to
3350 * take the load in an attempt to prevent getnewbuf() from blocking.
3352 static struct kproc_desc buf_kp = {
3357 SYSINIT(bufdaemon, SI_SUB_KTHREAD_BUF, SI_ORDER_FIRST, kproc_start, &buf_kp);
3360 buf_flush(struct vnode *vp, struct bufdomain *bd, int target)
3364 flushed = flushbufqueues(vp, bd, target, 0);
3367 * Could not find any buffers without rollback
3368 * dependencies, so just write the first one
3369 * in the hopes of eventually making progress.
3371 if (vp != NULL && target > 2)
3373 flushbufqueues(vp, bd, target, 1);
3381 struct bufdomain *bd;
3387 * This process needs to be suspended prior to shutdown sync.
3389 EVENTHANDLER_REGISTER(shutdown_pre_sync, kthread_shutdown, curthread,
3390 SHUTDOWN_PRI_LAST + 100);
3393 * Start the buf clean daemons as children threads.
3395 for (i = 0 ; i < buf_domains; i++) {
3398 error = kthread_add((void (*)(void *))bufspace_daemon,
3399 &bdomain[i], curproc, NULL, 0, 0, "bufspacedaemon-%d", i);
3401 panic("error %d spawning bufspace daemon", error);
3405 * This process is allowed to take the buffer cache to the limit
3407 curthread->td_pflags |= TDP_NORUNNINGBUF | TDP_BUFNEED;
3411 mtx_unlock(&bdlock);
3413 kthread_suspend_check();
3416 * Save speedupreq for this pass and reset to capture new
3419 speedupreq = bd_speedupreq;
3423 * Flush each domain sequentially according to its level and
3424 * the speedup request.
3426 for (i = 0; i < buf_domains; i++) {
3429 lodirty = bd->bd_numdirtybuffers / 2;
3431 lodirty = bd->bd_lodirtybuffers;
3432 while (bd->bd_numdirtybuffers > lodirty) {
3433 if (buf_flush(NULL, bd,
3434 bd->bd_numdirtybuffers - lodirty) == 0)
3436 kern_yield(PRI_USER);
3441 * Only clear bd_request if we have reached our low water
3442 * mark. The buf_daemon normally waits 1 second and
3443 * then incrementally flushes any dirty buffers that have
3444 * built up, within reason.
3446 * If we were unable to hit our low water mark and couldn't
3447 * find any flushable buffers, we sleep for a short period
3448 * to avoid endless loops on unlockable buffers.
3451 if (!BIT_EMPTY(BUF_DOMAINS, &bdlodirty)) {
3453 * We reached our low water mark, reset the
3454 * request and sleep until we are needed again.
3455 * The sleep is just so the suspend code works.
3459 * Do an extra wakeup in case dirty threshold
3460 * changed via sysctl and the explicit transition
3461 * out of shortfall was missed.
3464 if (runningbufspace <= lorunningspace)
3466 msleep(&bd_request, &bdlock, PVM, "psleep", hz);
3469 * We couldn't find any flushable dirty buffers but
3470 * still have too many dirty buffers, we
3471 * have to sleep and try again. (rare)
3473 msleep(&bd_request, &bdlock, PVM, "qsleep", hz / 10);
3481 * Try to flush a buffer in the dirty queue. We must be careful to
3482 * free up B_INVAL buffers instead of write them, which NFS is
3483 * particularly sensitive to.
3485 static int flushwithdeps = 0;
3486 SYSCTL_INT(_vfs, OID_AUTO, flushwithdeps, CTLFLAG_RW | CTLFLAG_STATS,
3488 "Number of buffers flushed with dependencies that require rollbacks");
3491 flushbufqueues(struct vnode *lvp, struct bufdomain *bd, int target,
3494 struct bufqueue *bq;
3495 struct buf *sentinel;
3505 bq = &bd->bd_dirtyq;
3507 sentinel = malloc(sizeof(struct buf), M_TEMP, M_WAITOK | M_ZERO);
3508 sentinel->b_qindex = QUEUE_SENTINEL;
3510 TAILQ_INSERT_HEAD(&bq->bq_queue, sentinel, b_freelist);
3512 while (flushed != target) {
3515 bp = TAILQ_NEXT(sentinel, b_freelist);
3517 TAILQ_REMOVE(&bq->bq_queue, sentinel, b_freelist);
3518 TAILQ_INSERT_AFTER(&bq->bq_queue, bp, sentinel,
3525 * Skip sentinels inserted by other invocations of the
3526 * flushbufqueues(), taking care to not reorder them.
3528 * Only flush the buffers that belong to the
3529 * vnode locked by the curthread.
3531 if (bp->b_qindex == QUEUE_SENTINEL || (lvp != NULL &&
3536 error = BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL);
3542 * BKGRDINPROG can only be set with the buf and bufobj
3543 * locks both held. We tolerate a race to clear it here.
3545 if ((bp->b_vflags & BV_BKGRDINPROG) != 0 ||
3546 (bp->b_flags & B_DELWRI) == 0) {
3550 if (bp->b_flags & B_INVAL) {
3557 if (!LIST_EMPTY(&bp->b_dep) && buf_countdeps(bp, 0)) {
3558 if (flushdeps == 0) {
3566 * We must hold the lock on a vnode before writing
3567 * one of its buffers. Otherwise we may confuse, or
3568 * in the case of a snapshot vnode, deadlock the
3571 * The lock order here is the reverse of the normal
3572 * of vnode followed by buf lock. This is ok because
3573 * the NOWAIT will prevent deadlock.
3576 if (vn_start_write(vp, &mp, V_NOWAIT) != 0) {
3582 error = vn_lock(vp, LK_EXCLUSIVE | LK_NOWAIT);
3584 ASSERT_VOP_LOCKED(vp, "getbuf");
3586 error = VOP_ISLOCKED(vp) == LK_EXCLUSIVE ? 0 :
3587 vn_lock(vp, LK_TRYUPGRADE);
3590 CTR3(KTR_BUF, "flushbufqueue(%p) vp %p flags %X",
3591 bp, bp->b_vp, bp->b_flags);
3592 if (curproc == bufdaemonproc) {
3597 counter_u64_add(notbufdflushes, 1);
3599 vn_finished_write(mp);
3602 flushwithdeps += hasdeps;
3606 * Sleeping on runningbufspace while holding
3607 * vnode lock leads to deadlock.
3609 if (curproc == bufdaemonproc &&
3610 runningbufspace > hirunningspace)
3611 waitrunningbufspace();
3614 vn_finished_write(mp);
3618 TAILQ_REMOVE(&bq->bq_queue, sentinel, b_freelist);
3620 free(sentinel, M_TEMP);
3625 * Check to see if a block is currently memory resident.
3628 incore(struct bufobj *bo, daddr_t blkno)
3630 return (gbincore_unlocked(bo, blkno));
3634 * Returns true if no I/O is needed to access the
3635 * associated VM object. This is like incore except
3636 * it also hunts around in the VM system for the data.
3639 inmem(struct vnode * vp, daddr_t blkno)
3642 vm_offset_t toff, tinc, size;
3647 ASSERT_VOP_LOCKED(vp, "inmem");
3649 if (incore(&vp->v_bufobj, blkno))
3651 if (vp->v_mount == NULL)
3658 if (size > vp->v_mount->mnt_stat.f_iosize)
3659 size = vp->v_mount->mnt_stat.f_iosize;
3660 off = (vm_ooffset_t)blkno * (vm_ooffset_t)vp->v_mount->mnt_stat.f_iosize;
3662 for (toff = 0; toff < vp->v_mount->mnt_stat.f_iosize; toff += tinc) {
3663 m = vm_page_lookup_unlocked(obj, OFF_TO_IDX(off + toff));
3669 if (tinc > PAGE_SIZE - ((toff + off) & PAGE_MASK))
3670 tinc = PAGE_SIZE - ((toff + off) & PAGE_MASK);
3672 * Consider page validity only if page mapping didn't change
3675 valid = vm_page_is_valid(m,
3676 (vm_offset_t)((toff + off) & PAGE_MASK), tinc);
3677 n = vm_page_lookup_unlocked(obj, OFF_TO_IDX(off + toff));
3689 * Set the dirty range for a buffer based on the status of the dirty
3690 * bits in the pages comprising the buffer. The range is limited
3691 * to the size of the buffer.
3693 * Tell the VM system that the pages associated with this buffer
3694 * are clean. This is used for delayed writes where the data is
3695 * going to go to disk eventually without additional VM intevention.
3697 * Note that while we only really need to clean through to b_bcount, we
3698 * just go ahead and clean through to b_bufsize.
3701 vfs_clean_pages_dirty_buf(struct buf *bp)
3703 vm_ooffset_t foff, noff, eoff;
3707 if ((bp->b_flags & B_VMIO) == 0 || bp->b_bufsize == 0)
3710 foff = bp->b_offset;
3711 KASSERT(bp->b_offset != NOOFFSET,
3712 ("vfs_clean_pages_dirty_buf: no buffer offset"));
3714 vfs_busy_pages_acquire(bp);
3715 vfs_setdirty_range(bp);
3716 for (i = 0; i < bp->b_npages; i++) {
3717 noff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK;
3719 if (eoff > bp->b_offset + bp->b_bufsize)
3720 eoff = bp->b_offset + bp->b_bufsize;
3722 vfs_page_set_validclean(bp, foff, m);
3723 /* vm_page_clear_dirty(m, foff & PAGE_MASK, eoff - foff); */
3726 vfs_busy_pages_release(bp);
3730 vfs_setdirty_range(struct buf *bp)
3732 vm_offset_t boffset;
3733 vm_offset_t eoffset;
3737 * test the pages to see if they have been modified directly
3738 * by users through the VM system.
3740 for (i = 0; i < bp->b_npages; i++)
3741 vm_page_test_dirty(bp->b_pages[i]);
3744 * Calculate the encompassing dirty range, boffset and eoffset,
3745 * (eoffset - boffset) bytes.
3748 for (i = 0; i < bp->b_npages; i++) {
3749 if (bp->b_pages[i]->dirty)
3752 boffset = (i << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK);
3754 for (i = bp->b_npages - 1; i >= 0; --i) {
3755 if (bp->b_pages[i]->dirty) {
3759 eoffset = ((i + 1) << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK);
3762 * Fit it to the buffer.
3765 if (eoffset > bp->b_bcount)
3766 eoffset = bp->b_bcount;
3769 * If we have a good dirty range, merge with the existing
3773 if (boffset < eoffset) {
3774 if (bp->b_dirtyoff > boffset)
3775 bp->b_dirtyoff = boffset;
3776 if (bp->b_dirtyend < eoffset)
3777 bp->b_dirtyend = eoffset;
3782 * Allocate the KVA mapping for an existing buffer.
3783 * If an unmapped buffer is provided but a mapped buffer is requested, take
3784 * also care to properly setup mappings between pages and KVA.
3787 bp_unmapped_get_kva(struct buf *bp, daddr_t blkno, int size, int gbflags)
3789 int bsize, maxsize, need_mapping, need_kva;
3792 need_mapping = bp->b_data == unmapped_buf &&
3793 (gbflags & GB_UNMAPPED) == 0;
3794 need_kva = bp->b_kvabase == unmapped_buf &&
3795 bp->b_data == unmapped_buf &&
3796 (gbflags & GB_KVAALLOC) != 0;
3797 if (!need_mapping && !need_kva)
3800 BUF_CHECK_UNMAPPED(bp);
3802 if (need_mapping && bp->b_kvabase != unmapped_buf) {
3804 * Buffer is not mapped, but the KVA was already
3805 * reserved at the time of the instantiation. Use the
3812 * Calculate the amount of the address space we would reserve
3813 * if the buffer was mapped.
3815 bsize = vn_isdisk(bp->b_vp) ? DEV_BSIZE : bp->b_bufobj->bo_bsize;
3816 KASSERT(bsize != 0, ("bsize == 0, check bo->bo_bsize"));
3817 offset = blkno * bsize;
3818 maxsize = size + (offset & PAGE_MASK);
3819 maxsize = imax(maxsize, bsize);
3821 while (bufkva_alloc(bp, maxsize, gbflags) != 0) {
3822 if ((gbflags & GB_NOWAIT_BD) != 0) {
3824 * XXXKIB: defragmentation cannot
3825 * succeed, not sure what else to do.
3827 panic("GB_NOWAIT_BD and GB_UNMAPPED %p", bp);
3829 counter_u64_add(mappingrestarts, 1);
3830 bufspace_wait(bufdomain(bp), bp->b_vp, gbflags, 0, 0);
3834 /* b_offset is handled by bpmap_qenter. */
3835 bp->b_data = bp->b_kvabase;
3836 BUF_CHECK_MAPPED(bp);
3842 getblk(struct vnode *vp, daddr_t blkno, int size, int slpflag, int slptimeo,
3848 error = getblkx(vp, blkno, blkno, size, slpflag, slptimeo, flags, &bp);
3857 * Get a block given a specified block and offset into a file/device.
3858 * The buffers B_DONE bit will be cleared on return, making it almost
3859 * ready for an I/O initiation. B_INVAL may or may not be set on
3860 * return. The caller should clear B_INVAL prior to initiating a
3863 * For a non-VMIO buffer, B_CACHE is set to the opposite of B_INVAL for
3864 * an existing buffer.
3866 * For a VMIO buffer, B_CACHE is modified according to the backing VM.
3867 * If getblk()ing a previously 0-sized invalid buffer, B_CACHE is set
3868 * and then cleared based on the backing VM. If the previous buffer is
3869 * non-0-sized but invalid, B_CACHE will be cleared.
3871 * If getblk() must create a new buffer, the new buffer is returned with
3872 * both B_INVAL and B_CACHE clear unless it is a VMIO buffer, in which
3873 * case it is returned with B_INVAL clear and B_CACHE set based on the
3876 * getblk() also forces a bwrite() for any B_DELWRI buffer whose
3877 * B_CACHE bit is clear.
3879 * What this means, basically, is that the caller should use B_CACHE to
3880 * determine whether the buffer is fully valid or not and should clear
3881 * B_INVAL prior to issuing a read. If the caller intends to validate
3882 * the buffer by loading its data area with something, the caller needs
3883 * to clear B_INVAL. If the caller does this without issuing an I/O,
3884 * the caller should set B_CACHE ( as an optimization ), else the caller
3885 * should issue the I/O and biodone() will set B_CACHE if the I/O was
3886 * a write attempt or if it was a successful read. If the caller
3887 * intends to issue a READ, the caller must clear B_INVAL and BIO_ERROR
3888 * prior to issuing the READ. biodone() will *not* clear B_INVAL.
3890 * The blkno parameter is the logical block being requested. Normally
3891 * the mapping of logical block number to disk block address is done
3892 * by calling VOP_BMAP(). However, if the mapping is already known, the
3893 * disk block address can be passed using the dblkno parameter. If the
3894 * disk block address is not known, then the same value should be passed
3895 * for blkno and dblkno.
3898 getblkx(struct vnode *vp, daddr_t blkno, daddr_t dblkno, int size, int slpflag,
3899 int slptimeo, int flags, struct buf **bpp)
3904 int bsize, error, maxsize, vmio;
3907 CTR3(KTR_BUF, "getblk(%p, %ld, %d)", vp, (long)blkno, size);
3908 KASSERT((flags & (GB_UNMAPPED | GB_KVAALLOC)) != GB_KVAALLOC,
3909 ("GB_KVAALLOC only makes sense with GB_UNMAPPED"));
3910 if (vp->v_type != VCHR)
3911 ASSERT_VOP_LOCKED(vp, "getblk");
3912 if (size > maxbcachebuf)
3913 panic("getblk: size(%d) > maxbcachebuf(%d)\n", size,
3915 if (!unmapped_buf_allowed)
3916 flags &= ~(GB_UNMAPPED | GB_KVAALLOC);
3921 /* Attempt lockless lookup first. */
3922 bp = gbincore_unlocked(bo, blkno);
3924 goto newbuf_unlocked;
3926 error = BUF_TIMELOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL, "getblku", 0,
3931 /* Verify buf identify has not changed since lookup. */
3932 if (bp->b_bufobj == bo && bp->b_lblkno == blkno)
3933 goto foundbuf_fastpath;
3935 /* It changed, fallback to locked lookup. */
3940 bp = gbincore(bo, blkno);
3945 * Buffer is in-core. If the buffer is not busy nor managed,
3946 * it must be on a queue.
3948 lockflags = LK_EXCLUSIVE | LK_INTERLOCK |
3949 ((flags & GB_LOCK_NOWAIT) ? LK_NOWAIT : LK_SLEEPFAIL);
3951 error = BUF_TIMELOCK(bp, lockflags,
3952 BO_LOCKPTR(bo), "getblk", slpflag, slptimeo);
3955 * If we slept and got the lock we have to restart in case
3956 * the buffer changed identities.
3958 if (error == ENOLCK)
3960 /* We timed out or were interrupted. */
3961 else if (error != 0)
3965 /* If recursed, assume caller knows the rules. */
3966 if (BUF_LOCKRECURSED(bp))
3970 * The buffer is locked. B_CACHE is cleared if the buffer is
3971 * invalid. Otherwise, for a non-VMIO buffer, B_CACHE is set
3972 * and for a VMIO buffer B_CACHE is adjusted according to the
3975 if (bp->b_flags & B_INVAL)
3976 bp->b_flags &= ~B_CACHE;
3977 else if ((bp->b_flags & (B_VMIO | B_INVAL)) == 0)
3978 bp->b_flags |= B_CACHE;
3979 if (bp->b_flags & B_MANAGED)
3980 MPASS(bp->b_qindex == QUEUE_NONE);
3985 * check for size inconsistencies for non-VMIO case.
3987 if (bp->b_bcount != size) {
3988 if ((bp->b_flags & B_VMIO) == 0 ||
3989 (size > bp->b_kvasize)) {
3990 if (bp->b_flags & B_DELWRI) {
3991 bp->b_flags |= B_NOCACHE;
3994 if (LIST_EMPTY(&bp->b_dep)) {
3995 bp->b_flags |= B_RELBUF;
3998 bp->b_flags |= B_NOCACHE;
4007 * Handle the case of unmapped buffer which should
4008 * become mapped, or the buffer for which KVA
4009 * reservation is requested.
4011 bp_unmapped_get_kva(bp, blkno, size, flags);
4014 * If the size is inconsistent in the VMIO case, we can resize
4015 * the buffer. This might lead to B_CACHE getting set or
4016 * cleared. If the size has not changed, B_CACHE remains
4017 * unchanged from its previous state.
4021 KASSERT(bp->b_offset != NOOFFSET,
4022 ("getblk: no buffer offset"));
4025 * A buffer with B_DELWRI set and B_CACHE clear must
4026 * be committed before we can return the buffer in
4027 * order to prevent the caller from issuing a read
4028 * ( due to B_CACHE not being set ) and overwriting
4031 * Most callers, including NFS and FFS, need this to
4032 * operate properly either because they assume they
4033 * can issue a read if B_CACHE is not set, or because
4034 * ( for example ) an uncached B_DELWRI might loop due
4035 * to softupdates re-dirtying the buffer. In the latter
4036 * case, B_CACHE is set after the first write completes,
4037 * preventing further loops.
4038 * NOTE! b*write() sets B_CACHE. If we cleared B_CACHE
4039 * above while extending the buffer, we cannot allow the
4040 * buffer to remain with B_CACHE set after the write
4041 * completes or it will represent a corrupt state. To
4042 * deal with this we set B_NOCACHE to scrap the buffer
4045 * We might be able to do something fancy, like setting
4046 * B_CACHE in bwrite() except if B_DELWRI is already set,
4047 * so the below call doesn't set B_CACHE, but that gets real
4048 * confusing. This is much easier.
4051 if ((bp->b_flags & (B_CACHE|B_DELWRI)) == B_DELWRI) {
4052 bp->b_flags |= B_NOCACHE;
4056 bp->b_flags &= ~B_DONE;
4059 * Buffer is not in-core, create new buffer. The buffer
4060 * returned by getnewbuf() is locked. Note that the returned
4061 * buffer is also considered valid (not marked B_INVAL).
4066 * If the user does not want us to create the buffer, bail out
4069 if (flags & GB_NOCREAT)
4072 bsize = vn_isdisk(vp) ? DEV_BSIZE : bo->bo_bsize;
4073 KASSERT(bsize != 0, ("bsize == 0, check bo->bo_bsize"));
4074 offset = blkno * bsize;
4075 vmio = vp->v_object != NULL;
4077 maxsize = size + (offset & PAGE_MASK);
4080 /* Do not allow non-VMIO notmapped buffers. */
4081 flags &= ~(GB_UNMAPPED | GB_KVAALLOC);
4083 maxsize = imax(maxsize, bsize);
4084 if ((flags & GB_NOSPARSE) != 0 && vmio &&
4086 error = VOP_BMAP(vp, blkno, NULL, &d_blkno, 0, 0);
4087 KASSERT(error != EOPNOTSUPP,
4088 ("GB_NOSPARSE from fs not supporting bmap, vp %p",
4093 return (EJUSTRETURN);
4096 bp = getnewbuf(vp, slpflag, slptimeo, maxsize, flags);
4098 if (slpflag || slptimeo)
4101 * XXX This is here until the sleep path is diagnosed
4102 * enough to work under very low memory conditions.
4104 * There's an issue on low memory, 4BSD+non-preempt
4105 * systems (eg MIPS routers with 32MB RAM) where buffer
4106 * exhaustion occurs without sleeping for buffer
4107 * reclaimation. This just sticks in a loop and
4108 * constantly attempts to allocate a buffer, which
4109 * hits exhaustion and tries to wakeup bufdaemon.
4110 * This never happens because we never yield.
4112 * The real solution is to identify and fix these cases
4113 * so we aren't effectively busy-waiting in a loop
4114 * until the reclaimation path has cycles to run.
4116 kern_yield(PRI_USER);
4121 * This code is used to make sure that a buffer is not
4122 * created while the getnewbuf routine is blocked.
4123 * This can be a problem whether the vnode is locked or not.
4124 * If the buffer is created out from under us, we have to
4125 * throw away the one we just created.
4127 * Note: this must occur before we associate the buffer
4128 * with the vp especially considering limitations in
4129 * the splay tree implementation when dealing with duplicate
4133 if (gbincore(bo, blkno)) {
4135 bp->b_flags |= B_INVAL;
4136 bufspace_release(bufdomain(bp), maxsize);
4142 * Insert the buffer into the hash, so that it can
4143 * be found by incore.
4145 bp->b_lblkno = blkno;
4146 bp->b_blkno = d_blkno;
4147 bp->b_offset = offset;
4152 * set B_VMIO bit. allocbuf() the buffer bigger. Since the
4153 * buffer size starts out as 0, B_CACHE will be set by
4154 * allocbuf() for the VMIO case prior to it testing the
4155 * backing store for validity.
4159 bp->b_flags |= B_VMIO;
4160 KASSERT(vp->v_object == bp->b_bufobj->bo_object,
4161 ("ARGH! different b_bufobj->bo_object %p %p %p\n",
4162 bp, vp->v_object, bp->b_bufobj->bo_object));
4164 bp->b_flags &= ~B_VMIO;
4165 KASSERT(bp->b_bufobj->bo_object == NULL,
4166 ("ARGH! has b_bufobj->bo_object %p %p\n",
4167 bp, bp->b_bufobj->bo_object));
4168 BUF_CHECK_MAPPED(bp);
4172 bufspace_release(bufdomain(bp), maxsize);
4173 bp->b_flags &= ~B_DONE;
4175 CTR4(KTR_BUF, "getblk(%p, %ld, %d) = %p", vp, (long)blkno, size, bp);
4177 buf_track(bp, __func__);
4178 KASSERT(bp->b_bufobj == bo,
4179 ("bp %p wrong b_bufobj %p should be %p", bp, bp->b_bufobj, bo));
4185 * Get an empty, disassociated buffer of given size. The buffer is initially
4189 geteblk(int size, int flags)
4194 maxsize = (size + BKVAMASK) & ~BKVAMASK;
4195 while ((bp = getnewbuf(NULL, 0, 0, maxsize, flags)) == NULL) {
4196 if ((flags & GB_NOWAIT_BD) &&
4197 (curthread->td_pflags & TDP_BUFNEED) != 0)
4201 bufspace_release(bufdomain(bp), maxsize);
4202 bp->b_flags |= B_INVAL; /* b_dep cleared by getnewbuf() */
4207 * Truncate the backing store for a non-vmio buffer.
4210 vfs_nonvmio_truncate(struct buf *bp, int newbsize)
4213 if (bp->b_flags & B_MALLOC) {
4215 * malloced buffers are not shrunk
4217 if (newbsize == 0) {
4218 bufmallocadjust(bp, 0);
4219 free(bp->b_data, M_BIOBUF);
4220 bp->b_data = bp->b_kvabase;
4221 bp->b_flags &= ~B_MALLOC;
4225 vm_hold_free_pages(bp, newbsize);
4226 bufspace_adjust(bp, newbsize);
4230 * Extend the backing for a non-VMIO buffer.
4233 vfs_nonvmio_extend(struct buf *bp, int newbsize)
4239 * We only use malloced memory on the first allocation.
4240 * and revert to page-allocated memory when the buffer
4243 * There is a potential smp race here that could lead
4244 * to bufmallocspace slightly passing the max. It
4245 * is probably extremely rare and not worth worrying
4248 if (bp->b_bufsize == 0 && newbsize <= PAGE_SIZE/2 &&
4249 bufmallocspace < maxbufmallocspace) {
4250 bp->b_data = malloc(newbsize, M_BIOBUF, M_WAITOK);
4251 bp->b_flags |= B_MALLOC;
4252 bufmallocadjust(bp, newbsize);
4257 * If the buffer is growing on its other-than-first
4258 * allocation then we revert to the page-allocation
4263 if (bp->b_flags & B_MALLOC) {
4264 origbuf = bp->b_data;
4265 origbufsize = bp->b_bufsize;
4266 bp->b_data = bp->b_kvabase;
4267 bufmallocadjust(bp, 0);
4268 bp->b_flags &= ~B_MALLOC;
4269 newbsize = round_page(newbsize);
4271 vm_hold_load_pages(bp, (vm_offset_t) bp->b_data + bp->b_bufsize,
4272 (vm_offset_t) bp->b_data + newbsize);
4273 if (origbuf != NULL) {
4274 bcopy(origbuf, bp->b_data, origbufsize);
4275 free(origbuf, M_BIOBUF);
4277 bufspace_adjust(bp, newbsize);
4281 * This code constitutes the buffer memory from either anonymous system
4282 * memory (in the case of non-VMIO operations) or from an associated
4283 * VM object (in the case of VMIO operations). This code is able to
4284 * resize a buffer up or down.
4286 * Note that this code is tricky, and has many complications to resolve
4287 * deadlock or inconsistent data situations. Tread lightly!!!
4288 * There are B_CACHE and B_DELWRI interactions that must be dealt with by
4289 * the caller. Calling this code willy nilly can result in the loss of data.
4291 * allocbuf() only adjusts B_CACHE for VMIO buffers. getblk() deals with
4292 * B_CACHE for the non-VMIO case.
4295 allocbuf(struct buf *bp, int size)
4299 if (bp->b_bcount == size)
4302 if (bp->b_kvasize != 0 && bp->b_kvasize < size)
4303 panic("allocbuf: buffer too small");
4305 newbsize = roundup2(size, DEV_BSIZE);
4306 if ((bp->b_flags & B_VMIO) == 0) {
4307 if ((bp->b_flags & B_MALLOC) == 0)
4308 newbsize = round_page(newbsize);
4310 * Just get anonymous memory from the kernel. Don't
4311 * mess with B_CACHE.
4313 if (newbsize < bp->b_bufsize)
4314 vfs_nonvmio_truncate(bp, newbsize);
4315 else if (newbsize > bp->b_bufsize)
4316 vfs_nonvmio_extend(bp, newbsize);
4320 desiredpages = (size == 0) ? 0 :
4321 num_pages((bp->b_offset & PAGE_MASK) + newbsize);
4323 if (bp->b_flags & B_MALLOC)
4324 panic("allocbuf: VMIO buffer can't be malloced");
4326 * Set B_CACHE initially if buffer is 0 length or will become
4329 if (size == 0 || bp->b_bufsize == 0)
4330 bp->b_flags |= B_CACHE;
4332 if (newbsize < bp->b_bufsize)
4333 vfs_vmio_truncate(bp, desiredpages);
4334 /* XXX This looks as if it should be newbsize > b_bufsize */
4335 else if (size > bp->b_bcount)
4336 vfs_vmio_extend(bp, desiredpages, size);
4337 bufspace_adjust(bp, newbsize);
4339 bp->b_bcount = size; /* requested buffer size. */
4343 extern int inflight_transient_maps;
4345 static struct bio_queue nondump_bios;
4348 biodone(struct bio *bp)
4351 void (*done)(struct bio *);
4352 vm_offset_t start, end;
4354 biotrack(bp, __func__);
4357 * Avoid completing I/O when dumping after a panic since that may
4358 * result in a deadlock in the filesystem or pager code. Note that
4359 * this doesn't affect dumps that were started manually since we aim
4360 * to keep the system usable after it has been resumed.
4362 if (__predict_false(dumping && SCHEDULER_STOPPED())) {
4363 TAILQ_INSERT_HEAD(&nondump_bios, bp, bio_queue);
4366 if ((bp->bio_flags & BIO_TRANSIENT_MAPPING) != 0) {
4367 bp->bio_flags &= ~BIO_TRANSIENT_MAPPING;
4368 bp->bio_flags |= BIO_UNMAPPED;
4369 start = trunc_page((vm_offset_t)bp->bio_data);
4370 end = round_page((vm_offset_t)bp->bio_data + bp->bio_length);
4371 bp->bio_data = unmapped_buf;
4372 pmap_qremove(start, atop(end - start));
4373 vmem_free(transient_arena, start, end - start);
4374 atomic_add_int(&inflight_transient_maps, -1);
4376 done = bp->bio_done;
4378 mtxp = mtx_pool_find(mtxpool_sleep, bp);
4380 bp->bio_flags |= BIO_DONE;
4388 * Wait for a BIO to finish.
4391 biowait(struct bio *bp, const char *wchan)
4395 mtxp = mtx_pool_find(mtxpool_sleep, bp);
4397 while ((bp->bio_flags & BIO_DONE) == 0)
4398 msleep(bp, mtxp, PRIBIO, wchan, 0);
4400 if (bp->bio_error != 0)
4401 return (bp->bio_error);
4402 if (!(bp->bio_flags & BIO_ERROR))
4408 biofinish(struct bio *bp, struct devstat *stat, int error)
4412 bp->bio_error = error;
4413 bp->bio_flags |= BIO_ERROR;
4416 devstat_end_transaction_bio(stat, bp);
4420 #if defined(BUF_TRACKING) || defined(FULL_BUF_TRACKING)
4422 biotrack_buf(struct bio *bp, const char *location)
4425 buf_track(bp->bio_track_bp, location);
4432 * Wait for buffer I/O completion, returning error status. The buffer
4433 * is left locked and B_DONE on return. B_EINTR is converted into an EINTR
4434 * error and cleared.
4437 bufwait(struct buf *bp)
4439 if (bp->b_iocmd == BIO_READ)
4440 bwait(bp, PRIBIO, "biord");
4442 bwait(bp, PRIBIO, "biowr");
4443 if (bp->b_flags & B_EINTR) {
4444 bp->b_flags &= ~B_EINTR;
4447 if (bp->b_ioflags & BIO_ERROR) {
4448 return (bp->b_error ? bp->b_error : EIO);
4457 * Finish I/O on a buffer, optionally calling a completion function.
4458 * This is usually called from an interrupt so process blocking is
4461 * biodone is also responsible for setting B_CACHE in a B_VMIO bp.
4462 * In a non-VMIO bp, B_CACHE will be set on the next getblk()
4463 * assuming B_INVAL is clear.
4465 * For the VMIO case, we set B_CACHE if the op was a read and no
4466 * read error occurred, or if the op was a write. B_CACHE is never
4467 * set if the buffer is invalid or otherwise uncacheable.
4469 * bufdone does not mess with B_INVAL, allowing the I/O routine or the
4470 * initiator to leave B_INVAL set to brelse the buffer out of existence
4471 * in the biodone routine.
4474 bufdone(struct buf *bp)
4476 struct bufobj *dropobj;
4477 void (*biodone)(struct buf *);
4479 buf_track(bp, __func__);
4480 CTR3(KTR_BUF, "bufdone(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
4483 KASSERT(!(bp->b_flags & B_DONE), ("biodone: bp %p already done", bp));
4485 runningbufwakeup(bp);
4486 if (bp->b_iocmd == BIO_WRITE)
4487 dropobj = bp->b_bufobj;
4488 /* call optional completion function if requested */
4489 if (bp->b_iodone != NULL) {
4490 biodone = bp->b_iodone;
4491 bp->b_iodone = NULL;
4494 bufobj_wdrop(dropobj);
4497 if (bp->b_flags & B_VMIO) {
4499 * Set B_CACHE if the op was a normal read and no error
4500 * occurred. B_CACHE is set for writes in the b*write()
4503 if (bp->b_iocmd == BIO_READ &&
4504 !(bp->b_flags & (B_INVAL|B_NOCACHE)) &&
4505 !(bp->b_ioflags & BIO_ERROR))
4506 bp->b_flags |= B_CACHE;
4507 vfs_vmio_iodone(bp);
4509 if (!LIST_EMPTY(&bp->b_dep))
4511 if ((bp->b_flags & B_CKHASH) != 0) {
4512 KASSERT(bp->b_iocmd == BIO_READ,
4513 ("bufdone: b_iocmd %d not BIO_READ", bp->b_iocmd));
4514 KASSERT(buf_mapped(bp), ("bufdone: bp %p not mapped", bp));
4515 (*bp->b_ckhashcalc)(bp);
4518 * For asynchronous completions, release the buffer now. The brelse
4519 * will do a wakeup there if necessary - so no need to do a wakeup
4520 * here in the async case. The sync case always needs to do a wakeup.
4522 if (bp->b_flags & B_ASYNC) {
4523 if ((bp->b_flags & (B_NOCACHE | B_INVAL | B_RELBUF)) ||
4524 (bp->b_ioflags & BIO_ERROR))
4531 bufobj_wdrop(dropobj);
4535 * This routine is called in lieu of iodone in the case of
4536 * incomplete I/O. This keeps the busy status for pages
4540 vfs_unbusy_pages(struct buf *bp)
4546 runningbufwakeup(bp);
4547 if (!(bp->b_flags & B_VMIO))
4550 obj = bp->b_bufobj->bo_object;
4551 for (i = 0; i < bp->b_npages; i++) {
4553 if (m == bogus_page) {
4554 m = vm_page_relookup(obj, OFF_TO_IDX(bp->b_offset) + i);
4556 panic("vfs_unbusy_pages: page missing\n");
4558 if (buf_mapped(bp)) {
4559 BUF_CHECK_MAPPED(bp);
4560 pmap_qenter(trunc_page((vm_offset_t)bp->b_data),
4561 bp->b_pages, bp->b_npages);
4563 BUF_CHECK_UNMAPPED(bp);
4567 vm_object_pip_wakeupn(obj, bp->b_npages);
4571 * vfs_page_set_valid:
4573 * Set the valid bits in a page based on the supplied offset. The
4574 * range is restricted to the buffer's size.
4576 * This routine is typically called after a read completes.
4579 vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, vm_page_t m)
4584 * Compute the end offset, eoff, such that [off, eoff) does not span a
4585 * page boundary and eoff is not greater than the end of the buffer.
4586 * The end of the buffer, in this case, is our file EOF, not the
4587 * allocation size of the buffer.
4589 eoff = (off + PAGE_SIZE) & ~(vm_ooffset_t)PAGE_MASK;
4590 if (eoff > bp->b_offset + bp->b_bcount)
4591 eoff = bp->b_offset + bp->b_bcount;
4594 * Set valid range. This is typically the entire buffer and thus the
4598 vm_page_set_valid_range(m, off & PAGE_MASK, eoff - off);
4602 * vfs_page_set_validclean:
4604 * Set the valid bits and clear the dirty bits in a page based on the
4605 * supplied offset. The range is restricted to the buffer's size.
4608 vfs_page_set_validclean(struct buf *bp, vm_ooffset_t off, vm_page_t m)
4610 vm_ooffset_t soff, eoff;
4613 * Start and end offsets in buffer. eoff - soff may not cross a
4614 * page boundary or cross the end of the buffer. The end of the
4615 * buffer, in this case, is our file EOF, not the allocation size
4619 eoff = (off + PAGE_SIZE) & ~(off_t)PAGE_MASK;
4620 if (eoff > bp->b_offset + bp->b_bcount)
4621 eoff = bp->b_offset + bp->b_bcount;
4624 * Set valid range. This is typically the entire buffer and thus the
4628 vm_page_set_validclean(
4630 (vm_offset_t) (soff & PAGE_MASK),
4631 (vm_offset_t) (eoff - soff)
4637 * Acquire a shared busy on all pages in the buf.
4640 vfs_busy_pages_acquire(struct buf *bp)
4644 for (i = 0; i < bp->b_npages; i++)
4645 vm_page_busy_acquire(bp->b_pages[i], VM_ALLOC_SBUSY);
4649 vfs_busy_pages_release(struct buf *bp)
4653 for (i = 0; i < bp->b_npages; i++)
4654 vm_page_sunbusy(bp->b_pages[i]);
4658 * This routine is called before a device strategy routine.
4659 * It is used to tell the VM system that paging I/O is in
4660 * progress, and treat the pages associated with the buffer
4661 * almost as being exclusive busy. Also the object paging_in_progress
4662 * flag is handled to make sure that the object doesn't become
4665 * Since I/O has not been initiated yet, certain buffer flags
4666 * such as BIO_ERROR or B_INVAL may be in an inconsistent state
4667 * and should be ignored.
4670 vfs_busy_pages(struct buf *bp, int clear_modify)
4678 if (!(bp->b_flags & B_VMIO))
4681 obj = bp->b_bufobj->bo_object;
4682 foff = bp->b_offset;
4683 KASSERT(bp->b_offset != NOOFFSET,
4684 ("vfs_busy_pages: no buffer offset"));
4685 if ((bp->b_flags & B_CLUSTER) == 0) {
4686 vm_object_pip_add(obj, bp->b_npages);
4687 vfs_busy_pages_acquire(bp);
4689 if (bp->b_bufsize != 0)
4690 vfs_setdirty_range(bp);
4692 for (i = 0; i < bp->b_npages; i++) {
4694 vm_page_assert_sbusied(m);
4697 * When readying a buffer for a read ( i.e
4698 * clear_modify == 0 ), it is important to do
4699 * bogus_page replacement for valid pages in
4700 * partially instantiated buffers. Partially
4701 * instantiated buffers can, in turn, occur when
4702 * reconstituting a buffer from its VM backing store
4703 * base. We only have to do this if B_CACHE is
4704 * clear ( which causes the I/O to occur in the
4705 * first place ). The replacement prevents the read
4706 * I/O from overwriting potentially dirty VM-backed
4707 * pages. XXX bogus page replacement is, uh, bogus.
4708 * It may not work properly with small-block devices.
4709 * We need to find a better way.
4712 pmap_remove_write(m);
4713 vfs_page_set_validclean(bp, foff, m);
4714 } else if (vm_page_all_valid(m) &&
4715 (bp->b_flags & B_CACHE) == 0) {
4716 bp->b_pages[i] = bogus_page;
4719 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK;
4721 if (bogus && buf_mapped(bp)) {
4722 BUF_CHECK_MAPPED(bp);
4723 pmap_qenter(trunc_page((vm_offset_t)bp->b_data),
4724 bp->b_pages, bp->b_npages);
4729 * vfs_bio_set_valid:
4731 * Set the range within the buffer to valid. The range is
4732 * relative to the beginning of the buffer, b_offset. Note that
4733 * b_offset itself may be offset from the beginning of the first
4737 vfs_bio_set_valid(struct buf *bp, int base, int size)
4742 if (!(bp->b_flags & B_VMIO))
4746 * Fixup base to be relative to beginning of first page.
4747 * Set initial n to be the maximum number of bytes in the
4748 * first page that can be validated.
4750 base += (bp->b_offset & PAGE_MASK);
4751 n = PAGE_SIZE - (base & PAGE_MASK);
4754 * Busy may not be strictly necessary here because the pages are
4755 * unlikely to be fully valid and the vnode lock will synchronize
4756 * their access via getpages. It is grabbed for consistency with
4757 * other page validation.
4759 vfs_busy_pages_acquire(bp);
4760 for (i = base / PAGE_SIZE; size > 0 && i < bp->b_npages; ++i) {
4764 vm_page_set_valid_range(m, base & PAGE_MASK, n);
4769 vfs_busy_pages_release(bp);
4775 * If the specified buffer is a non-VMIO buffer, clear the entire
4776 * buffer. If the specified buffer is a VMIO buffer, clear and
4777 * validate only the previously invalid portions of the buffer.
4778 * This routine essentially fakes an I/O, so we need to clear
4779 * BIO_ERROR and B_INVAL.
4781 * Note that while we only theoretically need to clear through b_bcount,
4782 * we go ahead and clear through b_bufsize.
4785 vfs_bio_clrbuf(struct buf *bp)
4787 int i, j, mask, sa, ea, slide;
4789 if ((bp->b_flags & (B_VMIO | B_MALLOC)) != B_VMIO) {
4793 bp->b_flags &= ~B_INVAL;
4794 bp->b_ioflags &= ~BIO_ERROR;
4795 vfs_busy_pages_acquire(bp);
4796 sa = bp->b_offset & PAGE_MASK;
4798 for (i = 0; i < bp->b_npages; i++, sa = 0) {
4799 slide = imin(slide + PAGE_SIZE, bp->b_offset + bp->b_bufsize);
4800 ea = slide & PAGE_MASK;
4803 if (bp->b_pages[i] == bogus_page)
4806 mask = ((1 << ((ea - sa) / DEV_BSIZE)) - 1) << j;
4807 if ((bp->b_pages[i]->valid & mask) == mask)
4809 if ((bp->b_pages[i]->valid & mask) == 0)
4810 pmap_zero_page_area(bp->b_pages[i], sa, ea - sa);
4812 for (; sa < ea; sa += DEV_BSIZE, j++) {
4813 if ((bp->b_pages[i]->valid & (1 << j)) == 0) {
4814 pmap_zero_page_area(bp->b_pages[i],
4819 vm_page_set_valid_range(bp->b_pages[i], j * DEV_BSIZE,
4820 roundup2(ea - sa, DEV_BSIZE));
4822 vfs_busy_pages_release(bp);
4827 vfs_bio_bzero_buf(struct buf *bp, int base, int size)
4832 if (buf_mapped(bp)) {
4833 BUF_CHECK_MAPPED(bp);
4834 bzero(bp->b_data + base, size);
4836 BUF_CHECK_UNMAPPED(bp);
4837 n = PAGE_SIZE - (base & PAGE_MASK);
4838 for (i = base / PAGE_SIZE; size > 0 && i < bp->b_npages; ++i) {
4842 pmap_zero_page_area(m, base & PAGE_MASK, n);
4851 * Update buffer flags based on I/O request parameters, optionally releasing the
4852 * buffer. If it's VMIO or direct I/O, the buffer pages are released to the VM,
4853 * where they may be placed on a page queue (VMIO) or freed immediately (direct
4854 * I/O). Otherwise the buffer is released to the cache.
4857 b_io_dismiss(struct buf *bp, int ioflag, bool release)
4860 KASSERT((ioflag & IO_NOREUSE) == 0 || (ioflag & IO_VMIO) != 0,
4861 ("buf %p non-VMIO noreuse", bp));
4863 if ((ioflag & IO_DIRECT) != 0)
4864 bp->b_flags |= B_DIRECT;
4865 if ((ioflag & IO_EXT) != 0)
4866 bp->b_xflags |= BX_ALTDATA;
4867 if ((ioflag & (IO_VMIO | IO_DIRECT)) != 0 && LIST_EMPTY(&bp->b_dep)) {
4868 bp->b_flags |= B_RELBUF;
4869 if ((ioflag & IO_NOREUSE) != 0)
4870 bp->b_flags |= B_NOREUSE;
4878 vfs_bio_brelse(struct buf *bp, int ioflag)
4881 b_io_dismiss(bp, ioflag, true);
4885 vfs_bio_set_flags(struct buf *bp, int ioflag)
4888 b_io_dismiss(bp, ioflag, false);
4892 * vm_hold_load_pages and vm_hold_free_pages get pages into
4893 * a buffers address space. The pages are anonymous and are
4894 * not associated with a file object.
4897 vm_hold_load_pages(struct buf *bp, vm_offset_t from, vm_offset_t to)
4903 BUF_CHECK_MAPPED(bp);
4905 to = round_page(to);
4906 from = round_page(from);
4907 index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT;
4908 MPASS((bp->b_flags & B_MAXPHYS) == 0);
4909 KASSERT(to - from <= maxbcachebuf,
4910 ("vm_hold_load_pages too large %p %#jx %#jx %u",
4911 bp, (uintmax_t)from, (uintmax_t)to, maxbcachebuf));
4913 for (pg = from; pg < to; pg += PAGE_SIZE, index++) {
4915 * note: must allocate system pages since blocking here
4916 * could interfere with paging I/O, no matter which
4919 p = vm_page_alloc_noobj(VM_ALLOC_SYSTEM | VM_ALLOC_WIRED |
4920 VM_ALLOC_COUNT((to - pg) >> PAGE_SHIFT) | VM_ALLOC_WAITOK);
4921 pmap_qenter(pg, &p, 1);
4922 bp->b_pages[index] = p;
4924 bp->b_npages = index;
4927 /* Return pages associated with this buf to the vm system */
4929 vm_hold_free_pages(struct buf *bp, int newbsize)
4933 int index, newnpages;
4935 BUF_CHECK_MAPPED(bp);
4937 from = round_page((vm_offset_t)bp->b_data + newbsize);
4938 newnpages = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT;
4939 if (bp->b_npages > newnpages)
4940 pmap_qremove(from, bp->b_npages - newnpages);
4941 for (index = newnpages; index < bp->b_npages; index++) {
4942 p = bp->b_pages[index];
4943 bp->b_pages[index] = NULL;
4944 vm_page_unwire_noq(p);
4947 bp->b_npages = newnpages;
4951 * Map an IO request into kernel virtual address space.
4953 * All requests are (re)mapped into kernel VA space.
4954 * Notice that we use b_bufsize for the size of the buffer
4955 * to be mapped. b_bcount might be modified by the driver.
4957 * Note that even if the caller determines that the address space should
4958 * be valid, a race or a smaller-file mapped into a larger space may
4959 * actually cause vmapbuf() to fail, so all callers of vmapbuf() MUST
4960 * check the return value.
4962 * This function only works with pager buffers.
4965 vmapbuf(struct buf *bp, void *uaddr, size_t len, int mapbuf)
4970 MPASS((bp->b_flags & B_MAXPHYS) != 0);
4971 prot = VM_PROT_READ;
4972 if (bp->b_iocmd == BIO_READ)
4973 prot |= VM_PROT_WRITE; /* Less backwards than it looks */
4974 pidx = vm_fault_quick_hold_pages(&curproc->p_vmspace->vm_map,
4975 (vm_offset_t)uaddr, len, prot, bp->b_pages, PBUF_PAGES);
4978 bp->b_bufsize = len;
4979 bp->b_npages = pidx;
4980 bp->b_offset = ((vm_offset_t)uaddr) & PAGE_MASK;
4981 if (mapbuf || !unmapped_buf_allowed) {
4982 pmap_qenter((vm_offset_t)bp->b_kvabase, bp->b_pages, pidx);
4983 bp->b_data = bp->b_kvabase + bp->b_offset;
4985 bp->b_data = unmapped_buf;
4990 * Free the io map PTEs associated with this IO operation.
4991 * We also invalidate the TLB entries and restore the original b_addr.
4993 * This function only works with pager buffers.
4996 vunmapbuf(struct buf *bp)
5000 npages = bp->b_npages;
5002 pmap_qremove(trunc_page((vm_offset_t)bp->b_data), npages);
5003 vm_page_unhold_pages(bp->b_pages, npages);
5005 bp->b_data = unmapped_buf;
5009 bdone(struct buf *bp)
5013 mtxp = mtx_pool_find(mtxpool_sleep, bp);
5015 bp->b_flags |= B_DONE;
5021 bwait(struct buf *bp, u_char pri, const char *wchan)
5025 mtxp = mtx_pool_find(mtxpool_sleep, bp);
5027 while ((bp->b_flags & B_DONE) == 0)
5028 msleep(bp, mtxp, pri, wchan, 0);
5033 bufsync(struct bufobj *bo, int waitfor)
5036 return (VOP_FSYNC(bo2vnode(bo), waitfor, curthread));
5040 bufstrategy(struct bufobj *bo, struct buf *bp)
5046 KASSERT(vp == bo->bo_private, ("Inconsistent vnode bufstrategy"));
5047 KASSERT(vp->v_type != VCHR && vp->v_type != VBLK,
5048 ("Wrong vnode in bufstrategy(bp=%p, vp=%p)", bp, vp));
5049 i = VOP_STRATEGY(vp, bp);
5050 KASSERT(i == 0, ("VOP_STRATEGY failed bp=%p vp=%p", bp, bp->b_vp));
5054 * Initialize a struct bufobj before use. Memory is assumed zero filled.
5057 bufobj_init(struct bufobj *bo, void *private)
5059 static volatile int bufobj_cleanq;
5062 atomic_fetchadd_int(&bufobj_cleanq, 1) % buf_domains;
5063 rw_init(BO_LOCKPTR(bo), "bufobj interlock");
5064 bo->bo_private = private;
5065 TAILQ_INIT(&bo->bo_clean.bv_hd);
5066 TAILQ_INIT(&bo->bo_dirty.bv_hd);
5070 bufobj_wrefl(struct bufobj *bo)
5073 KASSERT(bo != NULL, ("NULL bo in bufobj_wref"));
5074 ASSERT_BO_WLOCKED(bo);
5079 bufobj_wref(struct bufobj *bo)
5082 KASSERT(bo != NULL, ("NULL bo in bufobj_wref"));
5089 bufobj_wdrop(struct bufobj *bo)
5092 KASSERT(bo != NULL, ("NULL bo in bufobj_wdrop"));
5094 KASSERT(bo->bo_numoutput > 0, ("bufobj_wdrop non-positive count"));
5095 if ((--bo->bo_numoutput == 0) && (bo->bo_flag & BO_WWAIT)) {
5096 bo->bo_flag &= ~BO_WWAIT;
5097 wakeup(&bo->bo_numoutput);
5103 bufobj_wwait(struct bufobj *bo, int slpflag, int timeo)
5107 KASSERT(bo != NULL, ("NULL bo in bufobj_wwait"));
5108 ASSERT_BO_WLOCKED(bo);
5110 while (bo->bo_numoutput) {
5111 bo->bo_flag |= BO_WWAIT;
5112 error = msleep(&bo->bo_numoutput, BO_LOCKPTR(bo),
5113 slpflag | (PRIBIO + 1), "bo_wwait", timeo);
5121 * Set bio_data or bio_ma for struct bio from the struct buf.
5124 bdata2bio(struct buf *bp, struct bio *bip)
5127 if (!buf_mapped(bp)) {
5128 KASSERT(unmapped_buf_allowed, ("unmapped"));
5129 bip->bio_ma = bp->b_pages;
5130 bip->bio_ma_n = bp->b_npages;
5131 bip->bio_data = unmapped_buf;
5132 bip->bio_ma_offset = (vm_offset_t)bp->b_offset & PAGE_MASK;
5133 bip->bio_flags |= BIO_UNMAPPED;
5134 KASSERT(round_page(bip->bio_ma_offset + bip->bio_length) /
5135 PAGE_SIZE == bp->b_npages,
5136 ("Buffer %p too short: %d %lld %d", bp, bip->bio_ma_offset,
5137 (long long)bip->bio_length, bip->bio_ma_n));
5139 bip->bio_data = bp->b_data;
5145 * The MIPS pmap code currently doesn't handle aliased pages.
5146 * The VIPT caches may not handle page aliasing themselves, leading
5147 * to data corruption.
5149 * As such, this code makes a system extremely unhappy if said
5150 * system doesn't support unaliasing the above situation in hardware.
5151 * Some "recent" systems (eg some mips24k/mips74k cores) don't enable
5152 * this feature at build time, so it has to be handled in software.
5154 * Once the MIPS pmap/cache code grows to support this function on
5155 * earlier chips, it should be flipped back off.
5158 static int buf_pager_relbuf = 1;
5160 static int buf_pager_relbuf = 0;
5162 SYSCTL_INT(_vfs, OID_AUTO, buf_pager_relbuf, CTLFLAG_RWTUN,
5163 &buf_pager_relbuf, 0,
5164 "Make buffer pager release buffers after reading");
5167 * The buffer pager. It uses buffer reads to validate pages.
5169 * In contrast to the generic local pager from vm/vnode_pager.c, this
5170 * pager correctly and easily handles volumes where the underlying
5171 * device block size is greater than the machine page size. The
5172 * buffer cache transparently extends the requested page run to be
5173 * aligned at the block boundary, and does the necessary bogus page
5174 * replacements in the addends to avoid obliterating already valid
5177 * The only non-trivial issue is that the exclusive busy state for
5178 * pages, which is assumed by the vm_pager_getpages() interface, is
5179 * incompatible with the VMIO buffer cache's desire to share-busy the
5180 * pages. This function performs a trivial downgrade of the pages'
5181 * state before reading buffers, and a less trivial upgrade from the
5182 * shared-busy to excl-busy state after the read.
5185 vfs_bio_getpages(struct vnode *vp, vm_page_t *ma, int count,
5186 int *rbehind, int *rahead, vbg_get_lblkno_t get_lblkno,
5187 vbg_get_blksize_t get_blksize)
5194 vm_ooffset_t la, lb, poff, poffe;
5196 int br_flags, error, i, pgsin, pgsin_a, pgsin_b;
5199 object = vp->v_object;
5202 la = IDX_TO_OFF(ma[count - 1]->pindex);
5203 if (la >= object->un_pager.vnp.vnp_size)
5204 return (VM_PAGER_BAD);
5207 * Change the meaning of la from where the last requested page starts
5208 * to where it ends, because that's the end of the requested region
5209 * and the start of the potential read-ahead region.
5212 lpart = la > object->un_pager.vnp.vnp_size;
5213 error = get_blksize(vp, get_lblkno(vp, IDX_TO_OFF(ma[0]->pindex)),
5216 return (VM_PAGER_ERROR);
5219 * Calculate read-ahead, behind and total pages.
5222 lb = IDX_TO_OFF(ma[0]->pindex);
5223 pgsin_b = OFF_TO_IDX(lb - rounddown2(lb, bo_bs));
5225 if (rbehind != NULL)
5227 pgsin_a = OFF_TO_IDX(roundup2(la, bo_bs) - la);
5228 if (la + IDX_TO_OFF(pgsin_a) >= object->un_pager.vnp.vnp_size)
5229 pgsin_a = OFF_TO_IDX(roundup2(object->un_pager.vnp.vnp_size,
5234 VM_CNT_INC(v_vnodein);
5235 VM_CNT_ADD(v_vnodepgsin, pgsin);
5237 br_flags = (mp != NULL && (mp->mnt_kern_flag & MNTK_UNMAPPED_BUFS)
5238 != 0) ? GB_UNMAPPED : 0;
5240 for (i = 0; i < count; i++) {
5241 if (ma[i] != bogus_page)
5242 vm_page_busy_downgrade(ma[i]);
5246 for (i = 0; i < count; i++) {
5248 if (m == bogus_page)
5252 * Pages are shared busy and the object lock is not
5253 * owned, which together allow for the pages'
5254 * invalidation. The racy test for validity avoids
5255 * useless creation of the buffer for the most typical
5256 * case when invalidation is not used in redo or for
5257 * parallel read. The shared->excl upgrade loop at
5258 * the end of the function catches the race in a
5259 * reliable way (protected by the object lock).
5261 if (vm_page_all_valid(m))
5264 poff = IDX_TO_OFF(m->pindex);
5265 poffe = MIN(poff + PAGE_SIZE, object->un_pager.vnp.vnp_size);
5266 for (; poff < poffe; poff += bsize) {
5267 lbn = get_lblkno(vp, poff);
5272 error = get_blksize(vp, lbn, &bsize);
5274 error = bread_gb(vp, lbn, bsize,
5275 curthread->td_ucred, br_flags, &bp);
5278 if (bp->b_rcred == curthread->td_ucred) {
5279 crfree(bp->b_rcred);
5280 bp->b_rcred = NOCRED;
5282 if (LIST_EMPTY(&bp->b_dep)) {
5284 * Invalidation clears m->valid, but
5285 * may leave B_CACHE flag if the
5286 * buffer existed at the invalidation
5287 * time. In this case, recycle the
5288 * buffer to do real read on next
5289 * bread() after redo.
5291 * Otherwise B_RELBUF is not strictly
5292 * necessary, enable to reduce buf
5295 if (buf_pager_relbuf ||
5296 !vm_page_all_valid(m))
5297 bp->b_flags |= B_RELBUF;
5299 bp->b_flags &= ~B_NOCACHE;
5305 KASSERT(1 /* racy, enable for debugging */ ||
5306 vm_page_all_valid(m) || i == count - 1,
5307 ("buf %d %p invalid", i, m));
5308 if (i == count - 1 && lpart) {
5309 if (!vm_page_none_valid(m) &&
5310 !vm_page_all_valid(m))
5311 vm_page_zero_invalid(m, TRUE);
5318 for (i = 0; i < count; i++) {
5319 if (ma[i] == bogus_page)
5321 if (vm_page_busy_tryupgrade(ma[i]) == 0) {
5322 vm_page_sunbusy(ma[i]);
5323 ma[i] = vm_page_grab_unlocked(object, ma[i]->pindex,
5328 * Since the pages were only sbusy while neither the
5329 * buffer nor the object lock was held by us, or
5330 * reallocated while vm_page_grab() slept for busy
5331 * relinguish, they could have been invalidated.
5332 * Recheck the valid bits and re-read as needed.
5334 * Note that the last page is made fully valid in the
5335 * read loop, and partial validity for the page at
5336 * index count - 1 could mean that the page was
5337 * invalidated or removed, so we must restart for
5340 if (!vm_page_all_valid(ma[i]))
5343 if (redo && error == 0)
5345 return (error != 0 ? VM_PAGER_ERROR : VM_PAGER_OK);
5348 #include "opt_ddb.h"
5350 #include <ddb/ddb.h>
5352 /* DDB command to show buffer data */
5353 DB_SHOW_COMMAND(buffer, db_show_buffer)
5356 struct buf *bp = (struct buf *)addr;
5357 #ifdef FULL_BUF_TRACKING
5362 db_printf("usage: show buffer <addr>\n");
5366 db_printf("buf at %p\n", bp);
5367 db_printf("b_flags = 0x%b, b_xflags=0x%b\n",
5368 (u_int)bp->b_flags, PRINT_BUF_FLAGS,
5369 (u_int)bp->b_xflags, PRINT_BUF_XFLAGS);
5370 db_printf("b_vflags=0x%b b_ioflags0x%b\n",
5371 (u_int)bp->b_vflags, PRINT_BUF_VFLAGS,
5372 (u_int)bp->b_ioflags, PRINT_BIO_FLAGS);
5374 "b_error = %d, b_bufsize = %ld, b_bcount = %ld, b_resid = %ld\n"
5375 "b_bufobj = (%p), b_data = %p\n, b_blkno = %jd, b_lblkno = %jd, "
5376 "b_vp = %p, b_dep = %p\n",
5377 bp->b_error, bp->b_bufsize, bp->b_bcount, bp->b_resid,
5378 bp->b_bufobj, bp->b_data, (intmax_t)bp->b_blkno,
5379 (intmax_t)bp->b_lblkno, bp->b_vp, bp->b_dep.lh_first);
5380 db_printf("b_kvabase = %p, b_kvasize = %d\n",
5381 bp->b_kvabase, bp->b_kvasize);
5384 db_printf("b_npages = %d, pages(OBJ, IDX, PA): ", bp->b_npages);
5385 for (i = 0; i < bp->b_npages; i++) {
5389 db_printf("(%p, 0x%lx, 0x%lx)", m->object,
5391 (u_long)VM_PAGE_TO_PHYS(m));
5393 db_printf("( ??? )");
5394 if ((i + 1) < bp->b_npages)
5399 BUF_LOCKPRINTINFO(bp);
5400 #if defined(FULL_BUF_TRACKING)
5401 db_printf("b_io_tracking: b_io_tcnt = %u\n", bp->b_io_tcnt);
5403 i = bp->b_io_tcnt % BUF_TRACKING_SIZE;
5404 for (j = 1; j <= BUF_TRACKING_SIZE; j++) {
5405 if (bp->b_io_tracking[BUF_TRACKING_ENTRY(i - j)] == NULL)
5407 db_printf(" %2u: %s\n", j,
5408 bp->b_io_tracking[BUF_TRACKING_ENTRY(i - j)]);
5410 #elif defined(BUF_TRACKING)
5411 db_printf("b_io_tracking: %s\n", bp->b_io_tracking);
5416 DB_SHOW_COMMAND(bufqueues, bufqueues)
5418 struct bufdomain *bd;
5423 db_printf("bqempty: %d\n", bqempty.bq_len);
5425 for (i = 0; i < buf_domains; i++) {
5427 db_printf("Buf domain %d\n", i);
5428 db_printf("\tfreebufs\t%d\n", bd->bd_freebuffers);
5429 db_printf("\tlofreebufs\t%d\n", bd->bd_lofreebuffers);
5430 db_printf("\thifreebufs\t%d\n", bd->bd_hifreebuffers);
5432 db_printf("\tbufspace\t%ld\n", bd->bd_bufspace);
5433 db_printf("\tmaxbufspace\t%ld\n", bd->bd_maxbufspace);
5434 db_printf("\thibufspace\t%ld\n", bd->bd_hibufspace);
5435 db_printf("\tlobufspace\t%ld\n", bd->bd_lobufspace);
5436 db_printf("\tbufspacethresh\t%ld\n", bd->bd_bufspacethresh);
5438 db_printf("\tnumdirtybuffers\t%d\n", bd->bd_numdirtybuffers);
5439 db_printf("\tlodirtybuffers\t%d\n", bd->bd_lodirtybuffers);
5440 db_printf("\thidirtybuffers\t%d\n", bd->bd_hidirtybuffers);
5441 db_printf("\tdirtybufthresh\t%d\n", bd->bd_dirtybufthresh);
5444 TAILQ_FOREACH(bp, &bd->bd_cleanq->bq_queue, b_freelist)
5445 total += bp->b_bufsize;
5446 db_printf("\tcleanq count\t%d (%ld)\n",
5447 bd->bd_cleanq->bq_len, total);
5449 TAILQ_FOREACH(bp, &bd->bd_dirtyq.bq_queue, b_freelist)
5450 total += bp->b_bufsize;
5451 db_printf("\tdirtyq count\t%d (%ld)\n",
5452 bd->bd_dirtyq.bq_len, total);
5453 db_printf("\twakeup\t\t%d\n", bd->bd_wanted);
5454 db_printf("\tlim\t\t%d\n", bd->bd_lim);
5455 db_printf("\tCPU ");
5456 for (j = 0; j <= mp_maxid; j++)
5457 db_printf("%d, ", bd->bd_subq[j].bq_len);
5461 for (j = 0; j < nbuf; j++) {
5463 if (bp->b_domain == i && BUF_ISLOCKED(bp)) {
5465 total += bp->b_bufsize;
5468 db_printf("\tLocked buffers: %d space %ld\n", cnt, total);
5471 for (j = 0; j < nbuf; j++) {
5473 if (bp->b_domain == i) {
5475 total += bp->b_bufsize;
5478 db_printf("\tTotal buffers: %d space %ld\n", cnt, total);
5482 DB_SHOW_COMMAND(lockedbufs, lockedbufs)
5487 for (i = 0; i < nbuf; i++) {
5489 if (BUF_ISLOCKED(bp)) {
5490 db_show_buffer((uintptr_t)bp, 1, 0, NULL);
5498 DB_SHOW_COMMAND(vnodebufs, db_show_vnodebufs)
5504 db_printf("usage: show vnodebufs <addr>\n");
5507 vp = (struct vnode *)addr;
5508 db_printf("Clean buffers:\n");
5509 TAILQ_FOREACH(bp, &vp->v_bufobj.bo_clean.bv_hd, b_bobufs) {
5510 db_show_buffer((uintptr_t)bp, 1, 0, NULL);
5513 db_printf("Dirty buffers:\n");
5514 TAILQ_FOREACH(bp, &vp->v_bufobj.bo_dirty.bv_hd, b_bobufs) {
5515 db_show_buffer((uintptr_t)bp, 1, 0, NULL);
5520 DB_COMMAND(countfreebufs, db_coundfreebufs)
5523 int i, used = 0, nfree = 0;
5526 db_printf("usage: countfreebufs\n");
5530 for (i = 0; i < nbuf; i++) {
5532 if (bp->b_qindex == QUEUE_EMPTY)
5538 db_printf("Counted %d free, %d used (%d tot)\n", nfree, used,
5540 db_printf("numfreebuffers is %d\n", numfreebuffers);