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 */
1447 if (!first_buf_printf)
1448 printf("Final sync complete\n");
1450 * Unmount filesystems
1452 if (!KERNEL_PANICKED())
1456 DELAY(100000); /* wait for console output to finish */
1460 bpmap_qenter(struct buf *bp)
1463 BUF_CHECK_MAPPED(bp);
1466 * bp->b_data is relative to bp->b_offset, but
1467 * bp->b_offset may be offset into the first page.
1469 bp->b_data = (caddr_t)trunc_page((vm_offset_t)bp->b_data);
1470 pmap_qenter((vm_offset_t)bp->b_data, bp->b_pages, bp->b_npages);
1471 bp->b_data = (caddr_t)((vm_offset_t)bp->b_data |
1472 (vm_offset_t)(bp->b_offset & PAGE_MASK));
1475 static inline struct bufdomain *
1476 bufdomain(struct buf *bp)
1479 return (&bdomain[bp->b_domain]);
1482 static struct bufqueue *
1483 bufqueue(struct buf *bp)
1486 switch (bp->b_qindex) {
1489 case QUEUE_SENTINEL:
1494 return (&bufdomain(bp)->bd_dirtyq);
1496 return (&bufdomain(bp)->bd_subq[bp->b_subqueue]);
1500 panic("bufqueue(%p): Unhandled type %d\n", bp, bp->b_qindex);
1504 * Return the locked bufqueue that bp is a member of.
1506 static struct bufqueue *
1507 bufqueue_acquire(struct buf *bp)
1509 struct bufqueue *bq, *nbq;
1512 * bp can be pushed from a per-cpu queue to the
1513 * cleanq while we're waiting on the lock. Retry
1514 * if the queues don't match.
1532 * Insert the buffer into the appropriate free list. Requires a
1533 * locked buffer on entry and buffer is unlocked before return.
1536 binsfree(struct buf *bp, int qindex)
1538 struct bufdomain *bd;
1539 struct bufqueue *bq;
1541 KASSERT(qindex == QUEUE_CLEAN || qindex == QUEUE_DIRTY,
1542 ("binsfree: Invalid qindex %d", qindex));
1543 BUF_ASSERT_XLOCKED(bp);
1546 * Handle delayed bremfree() processing.
1548 if (bp->b_flags & B_REMFREE) {
1549 if (bp->b_qindex == qindex) {
1550 bp->b_flags |= B_REUSE;
1551 bp->b_flags &= ~B_REMFREE;
1555 bq = bufqueue_acquire(bp);
1560 if (qindex == QUEUE_CLEAN) {
1561 if (bd->bd_lim != 0)
1562 bq = &bd->bd_subq[PCPU_GET(cpuid)];
1566 bq = &bd->bd_dirtyq;
1567 bq_insert(bq, bp, true);
1573 * Free a buffer to the buf zone once it no longer has valid contents.
1576 buf_free(struct buf *bp)
1579 if (bp->b_flags & B_REMFREE)
1581 if (bp->b_vflags & BV_BKGRDINPROG)
1582 panic("losing buffer 1");
1583 if (bp->b_rcred != NOCRED) {
1584 crfree(bp->b_rcred);
1585 bp->b_rcred = NOCRED;
1587 if (bp->b_wcred != NOCRED) {
1588 crfree(bp->b_wcred);
1589 bp->b_wcred = NOCRED;
1591 if (!LIST_EMPTY(&bp->b_dep))
1594 atomic_add_int(&bufdomain(bp)->bd_freebuffers, 1);
1595 MPASS((bp->b_flags & B_MAXPHYS) == 0);
1597 uma_zfree(buf_zone, bp);
1603 * Import bufs into the uma cache from the buf list. The system still
1604 * expects a static array of bufs and much of the synchronization
1605 * around bufs assumes type stable storage. As a result, UMA is used
1606 * only as a per-cpu cache of bufs still maintained on a global list.
1609 buf_import(void *arg, void **store, int cnt, int domain, int flags)
1615 for (i = 0; i < cnt; i++) {
1616 bp = TAILQ_FIRST(&bqempty.bq_queue);
1619 bq_remove(&bqempty, bp);
1622 BQ_UNLOCK(&bqempty);
1630 * Release bufs from the uma cache back to the buffer queues.
1633 buf_release(void *arg, void **store, int cnt)
1635 struct bufqueue *bq;
1641 for (i = 0; i < cnt; i++) {
1643 /* Inline bq_insert() to batch locking. */
1644 TAILQ_INSERT_TAIL(&bq->bq_queue, bp, b_freelist);
1645 bp->b_flags &= ~(B_AGE | B_REUSE);
1647 bp->b_qindex = bq->bq_index;
1655 * Allocate an empty buffer header.
1658 buf_alloc(struct bufdomain *bd)
1661 int freebufs, error;
1664 * We can only run out of bufs in the buf zone if the average buf
1665 * is less than BKVASIZE. In this case the actual wait/block will
1666 * come from buf_reycle() failing to flush one of these small bufs.
1669 freebufs = atomic_fetchadd_int(&bd->bd_freebuffers, -1);
1671 bp = uma_zalloc(buf_zone, M_NOWAIT);
1673 atomic_add_int(&bd->bd_freebuffers, 1);
1674 bufspace_daemon_wakeup(bd);
1675 counter_u64_add(numbufallocfails, 1);
1679 * Wake-up the bufspace daemon on transition below threshold.
1681 if (freebufs == bd->bd_lofreebuffers)
1682 bufspace_daemon_wakeup(bd);
1684 error = BUF_LOCK(bp, LK_EXCLUSIVE, NULL);
1685 KASSERT(error == 0, ("%s: BUF_LOCK on free buf %p: %d.", __func__, bp,
1689 KASSERT(bp->b_vp == NULL,
1690 ("bp: %p still has vnode %p.", bp, bp->b_vp));
1691 KASSERT((bp->b_flags & (B_DELWRI | B_NOREUSE)) == 0,
1692 ("invalid buffer %p flags %#x", bp, bp->b_flags));
1693 KASSERT((bp->b_xflags & (BX_VNCLEAN|BX_VNDIRTY)) == 0,
1694 ("bp: %p still on a buffer list. xflags %X", bp, bp->b_xflags));
1695 KASSERT(bp->b_npages == 0,
1696 ("bp: %p still has %d vm pages\n", bp, bp->b_npages));
1697 KASSERT(bp->b_kvasize == 0, ("bp: %p still has kva\n", bp));
1698 KASSERT(bp->b_bufsize == 0, ("bp: %p still has bufspace\n", bp));
1699 MPASS((bp->b_flags & B_MAXPHYS) == 0);
1701 bp->b_domain = BD_DOMAIN(bd);
1707 bp->b_blkno = bp->b_lblkno = 0;
1708 bp->b_offset = NOOFFSET;
1714 bp->b_dirtyoff = bp->b_dirtyend = 0;
1715 bp->b_bufobj = NULL;
1716 bp->b_data = bp->b_kvabase = unmapped_buf;
1717 bp->b_fsprivate1 = NULL;
1718 bp->b_fsprivate2 = NULL;
1719 bp->b_fsprivate3 = NULL;
1720 LIST_INIT(&bp->b_dep);
1728 * Free a buffer from the given bufqueue. kva controls whether the
1729 * freed buf must own some kva resources. This is used for
1733 buf_recycle(struct bufdomain *bd, bool kva)
1735 struct bufqueue *bq;
1736 struct buf *bp, *nbp;
1739 counter_u64_add(bufdefragcnt, 1);
1743 KASSERT(BQ_LOCKPTR(bq) == BD_LOCKPTR(bd),
1744 ("buf_recycle: Locks don't match"));
1745 nbp = TAILQ_FIRST(&bq->bq_queue);
1748 * Run scan, possibly freeing data and/or kva mappings on the fly
1751 while ((bp = nbp) != NULL) {
1753 * Calculate next bp (we can only use it if we do not
1754 * release the bqlock).
1756 nbp = TAILQ_NEXT(bp, b_freelist);
1759 * If we are defragging then we need a buffer with
1760 * some kva to reclaim.
1762 if (kva && bp->b_kvasize == 0)
1765 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0)
1769 * Implement a second chance algorithm for frequently
1772 if ((bp->b_flags & B_REUSE) != 0) {
1773 TAILQ_REMOVE(&bq->bq_queue, bp, b_freelist);
1774 TAILQ_INSERT_TAIL(&bq->bq_queue, bp, b_freelist);
1775 bp->b_flags &= ~B_REUSE;
1781 * Skip buffers with background writes in progress.
1783 if ((bp->b_vflags & BV_BKGRDINPROG) != 0) {
1788 KASSERT(bp->b_qindex == QUEUE_CLEAN,
1789 ("buf_recycle: inconsistent queue %d bp %p",
1791 KASSERT(bp->b_domain == BD_DOMAIN(bd),
1792 ("getnewbuf: queue domain %d doesn't match request %d",
1793 bp->b_domain, (int)BD_DOMAIN(bd)));
1795 * NOTE: nbp is now entirely invalid. We can only restart
1796 * the scan from this point on.
1802 * Requeue the background write buffer with error and
1805 if ((bp->b_vflags & BV_BKGRDERR) != 0) {
1808 nbp = TAILQ_FIRST(&bq->bq_queue);
1811 bp->b_flags |= B_INVAL;
1824 * Mark the buffer for removal from the appropriate free list.
1828 bremfree(struct buf *bp)
1831 CTR3(KTR_BUF, "bremfree(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
1832 KASSERT((bp->b_flags & B_REMFREE) == 0,
1833 ("bremfree: buffer %p already marked for delayed removal.", bp));
1834 KASSERT(bp->b_qindex != QUEUE_NONE,
1835 ("bremfree: buffer %p not on a queue.", bp));
1836 BUF_ASSERT_XLOCKED(bp);
1838 bp->b_flags |= B_REMFREE;
1844 * Force an immediate removal from a free list. Used only in nfs when
1845 * it abuses the b_freelist pointer.
1848 bremfreef(struct buf *bp)
1850 struct bufqueue *bq;
1852 bq = bufqueue_acquire(bp);
1858 bq_init(struct bufqueue *bq, int qindex, int subqueue, const char *lockname)
1861 mtx_init(&bq->bq_lock, lockname, NULL, MTX_DEF);
1862 TAILQ_INIT(&bq->bq_queue);
1864 bq->bq_index = qindex;
1865 bq->bq_subqueue = subqueue;
1869 bd_init(struct bufdomain *bd)
1873 bd->bd_cleanq = &bd->bd_subq[mp_maxid + 1];
1874 bq_init(bd->bd_cleanq, QUEUE_CLEAN, mp_maxid + 1, "bufq clean lock");
1875 bq_init(&bd->bd_dirtyq, QUEUE_DIRTY, -1, "bufq dirty lock");
1876 for (i = 0; i <= mp_maxid; i++)
1877 bq_init(&bd->bd_subq[i], QUEUE_CLEAN, i,
1878 "bufq clean subqueue lock");
1879 mtx_init(&bd->bd_run_lock, "bufspace daemon run lock", NULL, MTX_DEF);
1885 * Removes a buffer from the free list, must be called with the
1886 * correct qlock held.
1889 bq_remove(struct bufqueue *bq, struct buf *bp)
1892 CTR3(KTR_BUF, "bq_remove(%p) vp %p flags %X",
1893 bp, bp->b_vp, bp->b_flags);
1894 KASSERT(bp->b_qindex != QUEUE_NONE,
1895 ("bq_remove: buffer %p not on a queue.", bp));
1896 KASSERT(bufqueue(bp) == bq,
1897 ("bq_remove: Remove buffer %p from wrong queue.", bp));
1899 BQ_ASSERT_LOCKED(bq);
1900 if (bp->b_qindex != QUEUE_EMPTY) {
1901 BUF_ASSERT_XLOCKED(bp);
1903 KASSERT(bq->bq_len >= 1,
1904 ("queue %d underflow", bp->b_qindex));
1905 TAILQ_REMOVE(&bq->bq_queue, bp, b_freelist);
1907 bp->b_qindex = QUEUE_NONE;
1908 bp->b_flags &= ~(B_REMFREE | B_REUSE);
1912 bd_flush(struct bufdomain *bd, struct bufqueue *bq)
1916 BQ_ASSERT_LOCKED(bq);
1917 if (bq != bd->bd_cleanq) {
1919 while ((bp = TAILQ_FIRST(&bq->bq_queue)) != NULL) {
1920 TAILQ_REMOVE(&bq->bq_queue, bp, b_freelist);
1921 TAILQ_INSERT_TAIL(&bd->bd_cleanq->bq_queue, bp,
1923 bp->b_subqueue = bd->bd_cleanq->bq_subqueue;
1925 bd->bd_cleanq->bq_len += bq->bq_len;
1928 if (bd->bd_wanted) {
1930 wakeup(&bd->bd_wanted);
1932 if (bq != bd->bd_cleanq)
1937 bd_flushall(struct bufdomain *bd)
1939 struct bufqueue *bq;
1943 if (bd->bd_lim == 0)
1946 for (i = 0; i <= mp_maxid; i++) {
1947 bq = &bd->bd_subq[i];
1948 if (bq->bq_len == 0)
1960 bq_insert(struct bufqueue *bq, struct buf *bp, bool unlock)
1962 struct bufdomain *bd;
1964 if (bp->b_qindex != QUEUE_NONE)
1965 panic("bq_insert: free buffer %p onto another queue?", bp);
1968 if (bp->b_flags & B_AGE) {
1969 /* Place this buf directly on the real queue. */
1970 if (bq->bq_index == QUEUE_CLEAN)
1973 TAILQ_INSERT_HEAD(&bq->bq_queue, bp, b_freelist);
1976 TAILQ_INSERT_TAIL(&bq->bq_queue, bp, b_freelist);
1978 bp->b_flags &= ~(B_AGE | B_REUSE);
1980 bp->b_qindex = bq->bq_index;
1981 bp->b_subqueue = bq->bq_subqueue;
1984 * Unlock before we notify so that we don't wakeup a waiter that
1985 * fails a trylock on the buf and sleeps again.
1990 if (bp->b_qindex == QUEUE_CLEAN) {
1992 * Flush the per-cpu queue and notify any waiters.
1994 if (bd->bd_wanted || (bq != bd->bd_cleanq &&
1995 bq->bq_len >= bd->bd_lim))
2004 * Free the kva allocation for a buffer.
2008 bufkva_free(struct buf *bp)
2012 if (bp->b_kvasize == 0) {
2013 KASSERT(bp->b_kvabase == unmapped_buf &&
2014 bp->b_data == unmapped_buf,
2015 ("Leaked KVA space on %p", bp));
2016 } else if (buf_mapped(bp))
2017 BUF_CHECK_MAPPED(bp);
2019 BUF_CHECK_UNMAPPED(bp);
2021 if (bp->b_kvasize == 0)
2024 vmem_free(buffer_arena, (vm_offset_t)bp->b_kvabase, bp->b_kvasize);
2025 counter_u64_add(bufkvaspace, -bp->b_kvasize);
2026 counter_u64_add(buffreekvacnt, 1);
2027 bp->b_data = bp->b_kvabase = unmapped_buf;
2034 * Allocate the buffer KVA and set b_kvasize and b_kvabase.
2037 bufkva_alloc(struct buf *bp, int maxsize, int gbflags)
2042 KASSERT((gbflags & GB_UNMAPPED) == 0 || (gbflags & GB_KVAALLOC) != 0,
2043 ("Invalid gbflags 0x%x in %s", gbflags, __func__));
2044 MPASS((bp->b_flags & B_MAXPHYS) == 0);
2045 KASSERT(maxsize <= maxbcachebuf,
2046 ("bufkva_alloc kva too large %d %u", maxsize, maxbcachebuf));
2051 error = vmem_alloc(buffer_arena, maxsize, M_BESTFIT | M_NOWAIT, &addr);
2054 * Buffer map is too fragmented. Request the caller
2055 * to defragment the map.
2059 bp->b_kvabase = (caddr_t)addr;
2060 bp->b_kvasize = maxsize;
2061 counter_u64_add(bufkvaspace, bp->b_kvasize);
2062 if ((gbflags & GB_UNMAPPED) != 0) {
2063 bp->b_data = unmapped_buf;
2064 BUF_CHECK_UNMAPPED(bp);
2066 bp->b_data = bp->b_kvabase;
2067 BUF_CHECK_MAPPED(bp);
2075 * Reclaim buffer kva by freeing buffers holding kva. This is a vmem
2076 * callback that fires to avoid returning failure.
2079 bufkva_reclaim(vmem_t *vmem, int flags)
2086 for (i = 0; i < 5; i++) {
2087 for (q = 0; q < buf_domains; q++)
2088 if (buf_recycle(&bdomain[q], true) != 0)
2097 * Attempt to initiate asynchronous I/O on read-ahead blocks. We must
2098 * clear BIO_ERROR and B_INVAL prior to initiating I/O . If B_CACHE is set,
2099 * the buffer is valid and we do not have to do anything.
2102 breada(struct vnode * vp, daddr_t * rablkno, int * rabsize, int cnt,
2103 struct ucred * cred, int flags, void (*ckhashfunc)(struct buf *))
2111 for (i = 0; i < cnt; i++, rablkno++, rabsize++) {
2112 if (inmem(vp, *rablkno))
2114 rabp = getblk(vp, *rablkno, *rabsize, 0, 0, 0);
2115 if ((rabp->b_flags & B_CACHE) != 0) {
2122 racct_add_buf(curproc, rabp, 0);
2123 PROC_UNLOCK(curproc);
2126 td->td_ru.ru_inblock++;
2127 rabp->b_flags |= B_ASYNC;
2128 rabp->b_flags &= ~B_INVAL;
2129 if ((flags & GB_CKHASH) != 0) {
2130 rabp->b_flags |= B_CKHASH;
2131 rabp->b_ckhashcalc = ckhashfunc;
2133 rabp->b_ioflags &= ~BIO_ERROR;
2134 rabp->b_iocmd = BIO_READ;
2135 if (rabp->b_rcred == NOCRED && cred != NOCRED)
2136 rabp->b_rcred = crhold(cred);
2137 vfs_busy_pages(rabp, 0);
2139 rabp->b_iooffset = dbtob(rabp->b_blkno);
2145 * Entry point for bread() and breadn() via #defines in sys/buf.h.
2147 * Get a buffer with the specified data. Look in the cache first. We
2148 * must clear BIO_ERROR and B_INVAL prior to initiating I/O. If B_CACHE
2149 * is set, the buffer is valid and we do not have to do anything, see
2150 * getblk(). Also starts asynchronous I/O on read-ahead blocks.
2152 * Always return a NULL buffer pointer (in bpp) when returning an error.
2154 * The blkno parameter is the logical block being requested. Normally
2155 * the mapping of logical block number to disk block address is done
2156 * by calling VOP_BMAP(). However, if the mapping is already known, the
2157 * disk block address can be passed using the dblkno parameter. If the
2158 * disk block address is not known, then the same value should be passed
2159 * for blkno and dblkno.
2162 breadn_flags(struct vnode *vp, daddr_t blkno, daddr_t dblkno, int size,
2163 daddr_t *rablkno, int *rabsize, int cnt, struct ucred *cred, int flags,
2164 void (*ckhashfunc)(struct buf *), struct buf **bpp)
2168 int error, readwait, rv;
2170 CTR3(KTR_BUF, "breadn(%p, %jd, %d)", vp, blkno, size);
2173 * Can only return NULL if GB_LOCK_NOWAIT or GB_SPARSE flags
2176 error = getblkx(vp, blkno, dblkno, size, 0, 0, flags, &bp);
2181 KASSERT(blkno == bp->b_lblkno,
2182 ("getblkx returned buffer for blkno %jd instead of blkno %jd",
2183 (intmax_t)bp->b_lblkno, (intmax_t)blkno));
2184 flags &= ~GB_NOSPARSE;
2188 * If not found in cache, do some I/O
2191 if ((bp->b_flags & B_CACHE) == 0) {
2194 PROC_LOCK(td->td_proc);
2195 racct_add_buf(td->td_proc, bp, 0);
2196 PROC_UNLOCK(td->td_proc);
2199 td->td_ru.ru_inblock++;
2200 bp->b_iocmd = BIO_READ;
2201 bp->b_flags &= ~B_INVAL;
2202 if ((flags & GB_CKHASH) != 0) {
2203 bp->b_flags |= B_CKHASH;
2204 bp->b_ckhashcalc = ckhashfunc;
2206 if ((flags & GB_CVTENXIO) != 0)
2207 bp->b_xflags |= BX_CVTENXIO;
2208 bp->b_ioflags &= ~BIO_ERROR;
2209 if (bp->b_rcred == NOCRED && cred != NOCRED)
2210 bp->b_rcred = crhold(cred);
2211 vfs_busy_pages(bp, 0);
2212 bp->b_iooffset = dbtob(bp->b_blkno);
2218 * Attempt to initiate asynchronous I/O on read-ahead blocks.
2220 breada(vp, rablkno, rabsize, cnt, cred, flags, ckhashfunc);
2234 * Write, release buffer on completion. (Done by iodone
2235 * if async). Do not bother writing anything if the buffer
2238 * Note that we set B_CACHE here, indicating that buffer is
2239 * fully valid and thus cacheable. This is true even of NFS
2240 * now so we set it generally. This could be set either here
2241 * or in biodone() since the I/O is synchronous. We put it
2245 bufwrite(struct buf *bp)
2252 CTR3(KTR_BUF, "bufwrite(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
2253 if ((bp->b_bufobj->bo_flag & BO_DEAD) != 0) {
2254 bp->b_flags |= B_INVAL | B_RELBUF;
2255 bp->b_flags &= ~B_CACHE;
2259 if (bp->b_flags & B_INVAL) {
2264 if (bp->b_flags & B_BARRIER)
2265 atomic_add_long(&barrierwrites, 1);
2267 oldflags = bp->b_flags;
2269 KASSERT(!(bp->b_vflags & BV_BKGRDINPROG),
2270 ("FFS background buffer should not get here %p", bp));
2274 vp_md = vp->v_vflag & VV_MD;
2279 * Mark the buffer clean. Increment the bufobj write count
2280 * before bundirty() call, to prevent other thread from seeing
2281 * empty dirty list and zero counter for writes in progress,
2282 * falsely indicating that the bufobj is clean.
2284 bufobj_wref(bp->b_bufobj);
2287 bp->b_flags &= ~B_DONE;
2288 bp->b_ioflags &= ~BIO_ERROR;
2289 bp->b_flags |= B_CACHE;
2290 bp->b_iocmd = BIO_WRITE;
2292 vfs_busy_pages(bp, 1);
2295 * Normal bwrites pipeline writes
2297 bp->b_runningbufspace = bp->b_bufsize;
2298 space = atomic_fetchadd_long(&runningbufspace, bp->b_runningbufspace);
2303 racct_add_buf(curproc, bp, 1);
2304 PROC_UNLOCK(curproc);
2307 curthread->td_ru.ru_oublock++;
2308 if (oldflags & B_ASYNC)
2310 bp->b_iooffset = dbtob(bp->b_blkno);
2311 buf_track(bp, __func__);
2314 if ((oldflags & B_ASYNC) == 0) {
2315 int rtval = bufwait(bp);
2318 } else if (space > hirunningspace) {
2320 * don't allow the async write to saturate the I/O
2321 * system. We will not deadlock here because
2322 * we are blocking waiting for I/O that is already in-progress
2323 * to complete. We do not block here if it is the update
2324 * or syncer daemon trying to clean up as that can lead
2327 if ((curthread->td_pflags & TDP_NORUNNINGBUF) == 0 && !vp_md)
2328 waitrunningbufspace();
2335 bufbdflush(struct bufobj *bo, struct buf *bp)
2338 struct bufdomain *bd;
2340 bd = &bdomain[bo->bo_domain];
2341 if (bo->bo_dirty.bv_cnt > bd->bd_dirtybufthresh + 10) {
2342 (void) VOP_FSYNC(bp->b_vp, MNT_NOWAIT, curthread);
2344 } else if (bo->bo_dirty.bv_cnt > bd->bd_dirtybufthresh) {
2347 * Try to find a buffer to flush.
2349 TAILQ_FOREACH(nbp, &bo->bo_dirty.bv_hd, b_bobufs) {
2350 if ((nbp->b_vflags & BV_BKGRDINPROG) ||
2352 LK_EXCLUSIVE | LK_NOWAIT, NULL))
2355 panic("bdwrite: found ourselves");
2357 /* Don't countdeps with the bo lock held. */
2358 if (buf_countdeps(nbp, 0)) {
2363 if (nbp->b_flags & B_CLUSTEROK) {
2364 vfs_bio_awrite(nbp);
2369 dirtybufferflushes++;
2378 * Delayed write. (Buffer is marked dirty). Do not bother writing
2379 * anything if the buffer is marked invalid.
2381 * Note that since the buffer must be completely valid, we can safely
2382 * set B_CACHE. In fact, we have to set B_CACHE here rather then in
2383 * biodone() in order to prevent getblk from writing the buffer
2384 * out synchronously.
2387 bdwrite(struct buf *bp)
2389 struct thread *td = curthread;
2393 CTR3(KTR_BUF, "bdwrite(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
2394 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp));
2395 KASSERT((bp->b_flags & B_BARRIER) == 0,
2396 ("Barrier request in delayed write %p", bp));
2398 if (bp->b_flags & B_INVAL) {
2404 * If we have too many dirty buffers, don't create any more.
2405 * If we are wildly over our limit, then force a complete
2406 * cleanup. Otherwise, just keep the situation from getting
2407 * out of control. Note that we have to avoid a recursive
2408 * disaster and not try to clean up after our own cleanup!
2412 if ((td->td_pflags & (TDP_COWINPROGRESS|TDP_INBDFLUSH)) == 0) {
2413 td->td_pflags |= TDP_INBDFLUSH;
2415 td->td_pflags &= ~TDP_INBDFLUSH;
2421 * Set B_CACHE, indicating that the buffer is fully valid. This is
2422 * true even of NFS now.
2424 bp->b_flags |= B_CACHE;
2427 * This bmap keeps the system from needing to do the bmap later,
2428 * perhaps when the system is attempting to do a sync. Since it
2429 * is likely that the indirect block -- or whatever other datastructure
2430 * that the filesystem needs is still in memory now, it is a good
2431 * thing to do this. Note also, that if the pageout daemon is
2432 * requesting a sync -- there might not be enough memory to do
2433 * the bmap then... So, this is important to do.
2435 if (vp->v_type != VCHR && bp->b_lblkno == bp->b_blkno) {
2436 VOP_BMAP(vp, bp->b_lblkno, NULL, &bp->b_blkno, NULL, NULL);
2439 buf_track(bp, __func__);
2442 * Set the *dirty* buffer range based upon the VM system dirty
2445 * Mark the buffer pages as clean. We need to do this here to
2446 * satisfy the vnode_pager and the pageout daemon, so that it
2447 * thinks that the pages have been "cleaned". Note that since
2448 * the pages are in a delayed write buffer -- the VFS layer
2449 * "will" see that the pages get written out on the next sync,
2450 * or perhaps the cluster will be completed.
2452 vfs_clean_pages_dirty_buf(bp);
2456 * note: we cannot initiate I/O from a bdwrite even if we wanted to,
2457 * due to the softdep code.
2464 * Turn buffer into delayed write request. We must clear BIO_READ and
2465 * B_RELBUF, and we must set B_DELWRI. We reassign the buffer to
2466 * itself to properly update it in the dirty/clean lists. We mark it
2467 * B_DONE to ensure that any asynchronization of the buffer properly
2468 * clears B_DONE ( else a panic will occur later ).
2470 * bdirty() is kinda like bdwrite() - we have to clear B_INVAL which
2471 * might have been set pre-getblk(). Unlike bwrite/bdwrite, bdirty()
2472 * should only be called if the buffer is known-good.
2474 * Since the buffer is not on a queue, we do not update the numfreebuffers
2477 * The buffer must be on QUEUE_NONE.
2480 bdirty(struct buf *bp)
2483 CTR3(KTR_BUF, "bdirty(%p) vp %p flags %X",
2484 bp, bp->b_vp, bp->b_flags);
2485 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp));
2486 KASSERT(bp->b_flags & B_REMFREE || bp->b_qindex == QUEUE_NONE,
2487 ("bdirty: buffer %p still on queue %d", bp, bp->b_qindex));
2488 bp->b_flags &= ~(B_RELBUF);
2489 bp->b_iocmd = BIO_WRITE;
2491 if ((bp->b_flags & B_DELWRI) == 0) {
2492 bp->b_flags |= /* XXX B_DONE | */ B_DELWRI;
2501 * Clear B_DELWRI for buffer.
2503 * Since the buffer is not on a queue, we do not update the numfreebuffers
2506 * The buffer must be on QUEUE_NONE.
2510 bundirty(struct buf *bp)
2513 CTR3(KTR_BUF, "bundirty(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
2514 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp));
2515 KASSERT(bp->b_flags & B_REMFREE || bp->b_qindex == QUEUE_NONE,
2516 ("bundirty: buffer %p still on queue %d", bp, bp->b_qindex));
2518 if (bp->b_flags & B_DELWRI) {
2519 bp->b_flags &= ~B_DELWRI;
2524 * Since it is now being written, we can clear its deferred write flag.
2526 bp->b_flags &= ~B_DEFERRED;
2532 * Asynchronous write. Start output on a buffer, but do not wait for
2533 * it to complete. The buffer is released when the output completes.
2535 * bwrite() ( or the VOP routine anyway ) is responsible for handling
2536 * B_INVAL buffers. Not us.
2539 bawrite(struct buf *bp)
2542 bp->b_flags |= B_ASYNC;
2549 * Asynchronous barrier write. Start output on a buffer, but do not
2550 * wait for it to complete. Place a write barrier after this write so
2551 * that this buffer and all buffers written before it are committed to
2552 * the disk before any buffers written after this write are committed
2553 * to the disk. The buffer is released when the output completes.
2556 babarrierwrite(struct buf *bp)
2559 bp->b_flags |= B_ASYNC | B_BARRIER;
2566 * Synchronous barrier write. Start output on a buffer and wait for
2567 * it to complete. Place a write barrier after this write so that
2568 * this buffer and all buffers written before it are committed to
2569 * the disk before any buffers written after this write are committed
2570 * to the disk. The buffer is released when the output completes.
2573 bbarrierwrite(struct buf *bp)
2576 bp->b_flags |= B_BARRIER;
2577 return (bwrite(bp));
2583 * Called prior to the locking of any vnodes when we are expecting to
2584 * write. We do not want to starve the buffer cache with too many
2585 * dirty buffers so we block here. By blocking prior to the locking
2586 * of any vnodes we attempt to avoid the situation where a locked vnode
2587 * prevents the various system daemons from flushing related buffers.
2593 if (buf_dirty_count_severe()) {
2594 mtx_lock(&bdirtylock);
2595 while (buf_dirty_count_severe()) {
2597 msleep(&bdirtywait, &bdirtylock, (PRIBIO + 4),
2600 mtx_unlock(&bdirtylock);
2605 * Return true if we have too many dirty buffers.
2608 buf_dirty_count_severe(void)
2611 return (!BIT_EMPTY(BUF_DOMAINS, &bdhidirty));
2617 * Release a busy buffer and, if requested, free its resources. The
2618 * buffer will be stashed in the appropriate bufqueue[] allowing it
2619 * to be accessed later as a cache entity or reused for other purposes.
2622 brelse(struct buf *bp)
2624 struct mount *v_mnt;
2628 * Many functions erroneously call brelse with a NULL bp under rare
2629 * error conditions. Simply return when called with a NULL bp.
2633 CTR3(KTR_BUF, "brelse(%p) vp %p flags %X",
2634 bp, bp->b_vp, bp->b_flags);
2635 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)),
2636 ("brelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp));
2637 KASSERT((bp->b_flags & B_VMIO) != 0 || (bp->b_flags & B_NOREUSE) == 0,
2638 ("brelse: non-VMIO buffer marked NOREUSE"));
2640 if (BUF_LOCKRECURSED(bp)) {
2642 * Do not process, in particular, do not handle the
2643 * B_INVAL/B_RELBUF and do not release to free list.
2649 if (bp->b_flags & B_MANAGED) {
2654 if (LIST_EMPTY(&bp->b_dep)) {
2655 bp->b_flags &= ~B_IOSTARTED;
2657 KASSERT((bp->b_flags & B_IOSTARTED) == 0,
2658 ("brelse: SU io not finished bp %p", bp));
2661 if ((bp->b_vflags & (BV_BKGRDINPROG | BV_BKGRDERR)) == BV_BKGRDERR) {
2662 BO_LOCK(bp->b_bufobj);
2663 bp->b_vflags &= ~BV_BKGRDERR;
2664 BO_UNLOCK(bp->b_bufobj);
2668 if (bp->b_iocmd == BIO_WRITE && (bp->b_ioflags & BIO_ERROR) &&
2669 (bp->b_flags & B_INVALONERR)) {
2671 * Forced invalidation of dirty buffer contents, to be used
2672 * after a failed write in the rare case that the loss of the
2673 * contents is acceptable. The buffer is invalidated and
2676 bp->b_flags |= B_INVAL | B_RELBUF | B_NOCACHE;
2677 bp->b_flags &= ~(B_ASYNC | B_CACHE);
2680 if (bp->b_iocmd == BIO_WRITE && (bp->b_ioflags & BIO_ERROR) &&
2681 (bp->b_error != ENXIO || !LIST_EMPTY(&bp->b_dep)) &&
2682 !(bp->b_flags & B_INVAL)) {
2684 * Failed write, redirty. All errors except ENXIO (which
2685 * means the device is gone) are treated as being
2688 * XXX Treating EIO as transient is not correct; the
2689 * contract with the local storage device drivers is that
2690 * they will only return EIO once the I/O is no longer
2691 * retriable. Network I/O also respects this through the
2692 * guarantees of TCP and/or the internal retries of NFS.
2693 * ENOMEM might be transient, but we also have no way of
2694 * knowing when its ok to retry/reschedule. In general,
2695 * this entire case should be made obsolete through better
2696 * error handling/recovery and resource scheduling.
2698 * Do this also for buffers that failed with ENXIO, but have
2699 * non-empty dependencies - the soft updates code might need
2700 * to access the buffer to untangle them.
2702 * Must clear BIO_ERROR to prevent pages from being scrapped.
2704 bp->b_ioflags &= ~BIO_ERROR;
2706 } else if ((bp->b_flags & (B_NOCACHE | B_INVAL)) ||
2707 (bp->b_ioflags & BIO_ERROR) || (bp->b_bufsize <= 0)) {
2709 * Either a failed read I/O, or we were asked to free or not
2710 * cache the buffer, or we failed to write to a device that's
2711 * no longer present.
2713 bp->b_flags |= B_INVAL;
2714 if (!LIST_EMPTY(&bp->b_dep))
2716 if (bp->b_flags & B_DELWRI)
2718 bp->b_flags &= ~(B_DELWRI | B_CACHE);
2719 if ((bp->b_flags & B_VMIO) == 0) {
2727 * We must clear B_RELBUF if B_DELWRI is set. If vfs_vmio_truncate()
2728 * is called with B_DELWRI set, the underlying pages may wind up
2729 * getting freed causing a previous write (bdwrite()) to get 'lost'
2730 * because pages associated with a B_DELWRI bp are marked clean.
2732 * We still allow the B_INVAL case to call vfs_vmio_truncate(), even
2733 * if B_DELWRI is set.
2735 if (bp->b_flags & B_DELWRI)
2736 bp->b_flags &= ~B_RELBUF;
2739 * VMIO buffer rundown. It is not very necessary to keep a VMIO buffer
2740 * constituted, not even NFS buffers now. Two flags effect this. If
2741 * B_INVAL, the struct buf is invalidated but the VM object is kept
2742 * around ( i.e. so it is trivial to reconstitute the buffer later ).
2744 * If BIO_ERROR or B_NOCACHE is set, pages in the VM object will be
2745 * invalidated. BIO_ERROR cannot be set for a failed write unless the
2746 * buffer is also B_INVAL because it hits the re-dirtying code above.
2748 * Normally we can do this whether a buffer is B_DELWRI or not. If
2749 * the buffer is an NFS buffer, it is tracking piecemeal writes or
2750 * the commit state and we cannot afford to lose the buffer. If the
2751 * buffer has a background write in progress, we need to keep it
2752 * around to prevent it from being reconstituted and starting a second
2756 v_mnt = bp->b_vp != NULL ? bp->b_vp->v_mount : NULL;
2758 if ((bp->b_flags & B_VMIO) && (bp->b_flags & B_NOCACHE ||
2759 (bp->b_ioflags & BIO_ERROR && bp->b_iocmd == BIO_READ)) &&
2760 (v_mnt == NULL || (v_mnt->mnt_vfc->vfc_flags & VFCF_NETWORK) == 0 ||
2761 vn_isdisk(bp->b_vp) || (bp->b_flags & B_DELWRI) == 0)) {
2762 vfs_vmio_invalidate(bp);
2766 if ((bp->b_flags & (B_INVAL | B_RELBUF)) != 0 ||
2767 (bp->b_flags & (B_DELWRI | B_NOREUSE)) == B_NOREUSE) {
2769 bp->b_flags &= ~B_NOREUSE;
2770 if (bp->b_vp != NULL)
2775 * If the buffer has junk contents signal it and eventually
2776 * clean up B_DELWRI and diassociate the vnode so that gbincore()
2779 if (bp->b_bufsize == 0 || (bp->b_ioflags & BIO_ERROR) != 0 ||
2780 (bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF)) != 0)
2781 bp->b_flags |= B_INVAL;
2782 if (bp->b_flags & B_INVAL) {
2783 if (bp->b_flags & B_DELWRI)
2789 buf_track(bp, __func__);
2791 /* buffers with no memory */
2792 if (bp->b_bufsize == 0) {
2796 /* buffers with junk contents */
2797 if (bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF) ||
2798 (bp->b_ioflags & BIO_ERROR)) {
2799 bp->b_xflags &= ~(BX_BKGRDWRITE | BX_ALTDATA);
2800 if (bp->b_vflags & BV_BKGRDINPROG)
2801 panic("losing buffer 2");
2802 qindex = QUEUE_CLEAN;
2803 bp->b_flags |= B_AGE;
2804 /* remaining buffers */
2805 } else if (bp->b_flags & B_DELWRI)
2806 qindex = QUEUE_DIRTY;
2808 qindex = QUEUE_CLEAN;
2810 if ((bp->b_flags & B_DELWRI) == 0 && (bp->b_xflags & BX_VNDIRTY))
2811 panic("brelse: not dirty");
2813 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_RELBUF | B_DIRECT);
2814 bp->b_xflags &= ~(BX_CVTENXIO);
2815 /* binsfree unlocks bp. */
2816 binsfree(bp, qindex);
2820 * Release a buffer back to the appropriate queue but do not try to free
2821 * it. The buffer is expected to be used again soon.
2823 * bqrelse() is used by bdwrite() to requeue a delayed write, and used by
2824 * biodone() to requeue an async I/O on completion. It is also used when
2825 * known good buffers need to be requeued but we think we may need the data
2828 * XXX we should be able to leave the B_RELBUF hint set on completion.
2831 bqrelse(struct buf *bp)
2835 CTR3(KTR_BUF, "bqrelse(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
2836 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)),
2837 ("bqrelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp));
2839 qindex = QUEUE_NONE;
2840 if (BUF_LOCKRECURSED(bp)) {
2841 /* do not release to free list */
2845 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF);
2846 bp->b_xflags &= ~(BX_CVTENXIO);
2848 if (LIST_EMPTY(&bp->b_dep)) {
2849 bp->b_flags &= ~B_IOSTARTED;
2851 KASSERT((bp->b_flags & B_IOSTARTED) == 0,
2852 ("bqrelse: SU io not finished bp %p", bp));
2855 if (bp->b_flags & B_MANAGED) {
2856 if (bp->b_flags & B_REMFREE)
2861 /* buffers with stale but valid contents */
2862 if ((bp->b_flags & B_DELWRI) != 0 || (bp->b_vflags & (BV_BKGRDINPROG |
2863 BV_BKGRDERR)) == BV_BKGRDERR) {
2864 BO_LOCK(bp->b_bufobj);
2865 bp->b_vflags &= ~BV_BKGRDERR;
2866 BO_UNLOCK(bp->b_bufobj);
2867 qindex = QUEUE_DIRTY;
2869 if ((bp->b_flags & B_DELWRI) == 0 &&
2870 (bp->b_xflags & BX_VNDIRTY))
2871 panic("bqrelse: not dirty");
2872 if ((bp->b_flags & B_NOREUSE) != 0) {
2876 qindex = QUEUE_CLEAN;
2878 buf_track(bp, __func__);
2879 /* binsfree unlocks bp. */
2880 binsfree(bp, qindex);
2884 buf_track(bp, __func__);
2890 * Complete I/O to a VMIO backed page. Validate the pages as appropriate,
2891 * restore bogus pages.
2894 vfs_vmio_iodone(struct buf *bp)
2899 struct vnode *vp __unused;
2900 int i, iosize, resid;
2903 obj = bp->b_bufobj->bo_object;
2904 KASSERT(blockcount_read(&obj->paging_in_progress) >= bp->b_npages,
2905 ("vfs_vmio_iodone: paging in progress(%d) < b_npages(%d)",
2906 blockcount_read(&obj->paging_in_progress), bp->b_npages));
2909 VNPASS(vp->v_holdcnt > 0, vp);
2910 VNPASS(vp->v_object != NULL, vp);
2912 foff = bp->b_offset;
2913 KASSERT(bp->b_offset != NOOFFSET,
2914 ("vfs_vmio_iodone: bp %p has no buffer offset", bp));
2917 iosize = bp->b_bcount - bp->b_resid;
2918 for (i = 0; i < bp->b_npages; i++) {
2919 resid = ((foff + PAGE_SIZE) & ~(off_t)PAGE_MASK) - foff;
2924 * cleanup bogus pages, restoring the originals
2927 if (m == bogus_page) {
2929 m = vm_page_relookup(obj, OFF_TO_IDX(foff));
2931 panic("biodone: page disappeared!");
2933 } else if ((bp->b_iocmd == BIO_READ) && resid > 0) {
2935 * In the write case, the valid and clean bits are
2936 * already changed correctly ( see bdwrite() ), so we
2937 * only need to do this here in the read case.
2939 KASSERT((m->dirty & vm_page_bits(foff & PAGE_MASK,
2940 resid)) == 0, ("vfs_vmio_iodone: page %p "
2941 "has unexpected dirty bits", m));
2942 vfs_page_set_valid(bp, foff, m);
2944 KASSERT(OFF_TO_IDX(foff) == m->pindex,
2945 ("vfs_vmio_iodone: foff(%jd)/pindex(%ju) mismatch",
2946 (intmax_t)foff, (uintmax_t)m->pindex));
2949 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK;
2952 vm_object_pip_wakeupn(obj, bp->b_npages);
2953 if (bogus && buf_mapped(bp)) {
2954 BUF_CHECK_MAPPED(bp);
2955 pmap_qenter(trunc_page((vm_offset_t)bp->b_data),
2956 bp->b_pages, bp->b_npages);
2961 * Perform page invalidation when a buffer is released. The fully invalid
2962 * pages will be reclaimed later in vfs_vmio_truncate().
2965 vfs_vmio_invalidate(struct buf *bp)
2969 int flags, i, resid, poffset, presid;
2971 if (buf_mapped(bp)) {
2972 BUF_CHECK_MAPPED(bp);
2973 pmap_qremove(trunc_page((vm_offset_t)bp->b_data), bp->b_npages);
2975 BUF_CHECK_UNMAPPED(bp);
2977 * Get the base offset and length of the buffer. Note that
2978 * in the VMIO case if the buffer block size is not
2979 * page-aligned then b_data pointer may not be page-aligned.
2980 * But our b_pages[] array *IS* page aligned.
2982 * block sizes less then DEV_BSIZE (usually 512) are not
2983 * supported due to the page granularity bits (m->valid,
2984 * m->dirty, etc...).
2986 * See man buf(9) for more information
2988 flags = (bp->b_flags & B_NOREUSE) != 0 ? VPR_NOREUSE : 0;
2989 obj = bp->b_bufobj->bo_object;
2990 resid = bp->b_bufsize;
2991 poffset = bp->b_offset & PAGE_MASK;
2992 VM_OBJECT_WLOCK(obj);
2993 for (i = 0; i < bp->b_npages; i++) {
2995 if (m == bogus_page)
2996 panic("vfs_vmio_invalidate: Unexpected bogus page.");
2997 bp->b_pages[i] = NULL;
2999 presid = resid > (PAGE_SIZE - poffset) ?
3000 (PAGE_SIZE - poffset) : resid;
3001 KASSERT(presid >= 0, ("brelse: extra page"));
3002 vm_page_busy_acquire(m, VM_ALLOC_SBUSY);
3003 if (pmap_page_wired_mappings(m) == 0)
3004 vm_page_set_invalid(m, poffset, presid);
3006 vm_page_release_locked(m, flags);
3010 VM_OBJECT_WUNLOCK(obj);
3015 * Page-granular truncation of an existing VMIO buffer.
3018 vfs_vmio_truncate(struct buf *bp, int desiredpages)
3024 if (bp->b_npages == desiredpages)
3027 if (buf_mapped(bp)) {
3028 BUF_CHECK_MAPPED(bp);
3029 pmap_qremove((vm_offset_t)trunc_page((vm_offset_t)bp->b_data) +
3030 (desiredpages << PAGE_SHIFT), bp->b_npages - desiredpages);
3032 BUF_CHECK_UNMAPPED(bp);
3035 * The object lock is needed only if we will attempt to free pages.
3037 flags = (bp->b_flags & B_NOREUSE) != 0 ? VPR_NOREUSE : 0;
3038 if ((bp->b_flags & B_DIRECT) != 0) {
3039 flags |= VPR_TRYFREE;
3040 obj = bp->b_bufobj->bo_object;
3041 VM_OBJECT_WLOCK(obj);
3045 for (i = desiredpages; i < bp->b_npages; i++) {
3047 KASSERT(m != bogus_page, ("allocbuf: bogus page found"));
3048 bp->b_pages[i] = NULL;
3050 vm_page_release_locked(m, flags);
3052 vm_page_release(m, flags);
3055 VM_OBJECT_WUNLOCK(obj);
3056 bp->b_npages = desiredpages;
3060 * Byte granular extension of VMIO buffers.
3063 vfs_vmio_extend(struct buf *bp, int desiredpages, int size)
3066 * We are growing the buffer, possibly in a
3067 * byte-granular fashion.
3075 * Step 1, bring in the VM pages from the object, allocating
3076 * them if necessary. We must clear B_CACHE if these pages
3077 * are not valid for the range covered by the buffer.
3079 obj = bp->b_bufobj->bo_object;
3080 if (bp->b_npages < desiredpages) {
3081 KASSERT(desiredpages <= atop(maxbcachebuf),
3082 ("vfs_vmio_extend past maxbcachebuf %p %d %u",
3083 bp, desiredpages, maxbcachebuf));
3086 * We must allocate system pages since blocking
3087 * here could interfere with paging I/O, no
3088 * matter which process we are.
3090 * Only exclusive busy can be tested here.
3091 * Blocking on shared busy might lead to
3092 * deadlocks once allocbuf() is called after
3093 * pages are vfs_busy_pages().
3095 (void)vm_page_grab_pages_unlocked(obj,
3096 OFF_TO_IDX(bp->b_offset) + bp->b_npages,
3097 VM_ALLOC_SYSTEM | VM_ALLOC_IGN_SBUSY |
3098 VM_ALLOC_NOBUSY | VM_ALLOC_WIRED,
3099 &bp->b_pages[bp->b_npages], desiredpages - bp->b_npages);
3100 bp->b_npages = desiredpages;
3104 * Step 2. We've loaded the pages into the buffer,
3105 * we have to figure out if we can still have B_CACHE
3106 * set. Note that B_CACHE is set according to the
3107 * byte-granular range ( bcount and size ), not the
3108 * aligned range ( newbsize ).
3110 * The VM test is against m->valid, which is DEV_BSIZE
3111 * aligned. Needless to say, the validity of the data
3112 * needs to also be DEV_BSIZE aligned. Note that this
3113 * fails with NFS if the server or some other client
3114 * extends the file's EOF. If our buffer is resized,
3115 * B_CACHE may remain set! XXX
3117 toff = bp->b_bcount;
3118 tinc = PAGE_SIZE - ((bp->b_offset + toff) & PAGE_MASK);
3119 while ((bp->b_flags & B_CACHE) && toff < size) {
3122 if (tinc > (size - toff))
3124 pi = ((bp->b_offset & PAGE_MASK) + toff) >> PAGE_SHIFT;
3125 m = bp->b_pages[pi];
3126 vfs_buf_test_cache(bp, bp->b_offset, toff, tinc, m);
3132 * Step 3, fixup the KVA pmap.
3137 BUF_CHECK_UNMAPPED(bp);
3141 * Check to see if a block at a particular lbn is available for a clustered
3145 vfs_bio_clcheck(struct vnode *vp, int size, daddr_t lblkno, daddr_t blkno)
3152 /* If the buf isn't in core skip it */
3153 if ((bpa = gbincore(&vp->v_bufobj, lblkno)) == NULL)
3156 /* If the buf is busy we don't want to wait for it */
3157 if (BUF_LOCK(bpa, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0)
3160 /* Only cluster with valid clusterable delayed write buffers */
3161 if ((bpa->b_flags & (B_DELWRI | B_CLUSTEROK | B_INVAL)) !=
3162 (B_DELWRI | B_CLUSTEROK))
3165 if (bpa->b_bufsize != size)
3169 * Check to see if it is in the expected place on disk and that the
3170 * block has been mapped.
3172 if ((bpa->b_blkno != bpa->b_lblkno) && (bpa->b_blkno == blkno))
3182 * Implement clustered async writes for clearing out B_DELWRI buffers.
3183 * This is much better then the old way of writing only one buffer at
3184 * a time. Note that we may not be presented with the buffers in the
3185 * correct order, so we search for the cluster in both directions.
3188 vfs_bio_awrite(struct buf *bp)
3193 daddr_t lblkno = bp->b_lblkno;
3194 struct vnode *vp = bp->b_vp;
3202 gbflags = (bp->b_data == unmapped_buf) ? GB_UNMAPPED : 0;
3204 * right now we support clustered writing only to regular files. If
3205 * we find a clusterable block we could be in the middle of a cluster
3206 * rather then at the beginning.
3208 if ((vp->v_type == VREG) &&
3209 (vp->v_mount != 0) && /* Only on nodes that have the size info */
3210 (bp->b_flags & (B_CLUSTEROK | B_INVAL)) == B_CLUSTEROK) {
3211 size = vp->v_mount->mnt_stat.f_iosize;
3212 maxcl = maxphys / size;
3215 for (i = 1; i < maxcl; i++)
3216 if (vfs_bio_clcheck(vp, size, lblkno + i,
3217 bp->b_blkno + ((i * size) >> DEV_BSHIFT)) == 0)
3220 for (j = 1; i + j <= maxcl && j <= lblkno; j++)
3221 if (vfs_bio_clcheck(vp, size, lblkno - j,
3222 bp->b_blkno - ((j * size) >> DEV_BSHIFT)) == 0)
3228 * this is a possible cluster write
3232 nwritten = cluster_wbuild(vp, size, lblkno - j, ncl,
3238 bp->b_flags |= B_ASYNC;
3240 * default (old) behavior, writing out only one block
3242 * XXX returns b_bufsize instead of b_bcount for nwritten?
3244 nwritten = bp->b_bufsize;
3253 * Allocate KVA for an empty buf header according to gbflags.
3256 getnewbuf_kva(struct buf *bp, int gbflags, int maxsize)
3259 if ((gbflags & (GB_UNMAPPED | GB_KVAALLOC)) != GB_UNMAPPED) {
3261 * In order to keep fragmentation sane we only allocate kva
3262 * in BKVASIZE chunks. XXX with vmem we can do page size.
3264 maxsize = (maxsize + BKVAMASK) & ~BKVAMASK;
3266 if (maxsize != bp->b_kvasize &&
3267 bufkva_alloc(bp, maxsize, gbflags))
3276 * Find and initialize a new buffer header, freeing up existing buffers
3277 * in the bufqueues as necessary. The new buffer is returned locked.
3280 * We have insufficient buffer headers
3281 * We have insufficient buffer space
3282 * buffer_arena is too fragmented ( space reservation fails )
3283 * If we have to flush dirty buffers ( but we try to avoid this )
3285 * The caller is responsible for releasing the reserved bufspace after
3286 * allocbuf() is called.
3289 getnewbuf(struct vnode *vp, int slpflag, int slptimeo, int maxsize, int gbflags)
3291 struct bufdomain *bd;
3293 bool metadata, reserved;
3296 KASSERT((gbflags & (GB_UNMAPPED | GB_KVAALLOC)) != GB_KVAALLOC,
3297 ("GB_KVAALLOC only makes sense with GB_UNMAPPED"));
3298 if (!unmapped_buf_allowed)
3299 gbflags &= ~(GB_UNMAPPED | GB_KVAALLOC);
3301 if (vp == NULL || (vp->v_vflag & (VV_MD | VV_SYSTEM)) != 0 ||
3309 bd = &bdomain[vp->v_bufobj.bo_domain];
3311 counter_u64_add(getnewbufcalls, 1);
3314 if (reserved == false &&
3315 bufspace_reserve(bd, maxsize, metadata) != 0) {
3316 counter_u64_add(getnewbufrestarts, 1);
3320 if ((bp = buf_alloc(bd)) == NULL) {
3321 counter_u64_add(getnewbufrestarts, 1);
3324 if (getnewbuf_kva(bp, gbflags, maxsize) == 0)
3327 } while (buf_recycle(bd, false) == 0);
3330 bufspace_release(bd, maxsize);
3332 bp->b_flags |= B_INVAL;
3335 bufspace_wait(bd, vp, gbflags, slpflag, slptimeo);
3343 * buffer flushing daemon. Buffers are normally flushed by the
3344 * update daemon but if it cannot keep up this process starts to
3345 * take the load in an attempt to prevent getnewbuf() from blocking.
3347 static struct kproc_desc buf_kp = {
3352 SYSINIT(bufdaemon, SI_SUB_KTHREAD_BUF, SI_ORDER_FIRST, kproc_start, &buf_kp);
3355 buf_flush(struct vnode *vp, struct bufdomain *bd, int target)
3359 flushed = flushbufqueues(vp, bd, target, 0);
3362 * Could not find any buffers without rollback
3363 * dependencies, so just write the first one
3364 * in the hopes of eventually making progress.
3366 if (vp != NULL && target > 2)
3368 flushbufqueues(vp, bd, target, 1);
3376 struct bufdomain *bd;
3382 * This process needs to be suspended prior to shutdown sync.
3384 EVENTHANDLER_REGISTER(shutdown_pre_sync, kthread_shutdown, curthread,
3385 SHUTDOWN_PRI_LAST + 100);
3388 * Start the buf clean daemons as children threads.
3390 for (i = 0 ; i < buf_domains; i++) {
3393 error = kthread_add((void (*)(void *))bufspace_daemon,
3394 &bdomain[i], curproc, NULL, 0, 0, "bufspacedaemon-%d", i);
3396 panic("error %d spawning bufspace daemon", error);
3400 * This process is allowed to take the buffer cache to the limit
3402 curthread->td_pflags |= TDP_NORUNNINGBUF | TDP_BUFNEED;
3406 mtx_unlock(&bdlock);
3408 kthread_suspend_check();
3411 * Save speedupreq for this pass and reset to capture new
3414 speedupreq = bd_speedupreq;
3418 * Flush each domain sequentially according to its level and
3419 * the speedup request.
3421 for (i = 0; i < buf_domains; i++) {
3424 lodirty = bd->bd_numdirtybuffers / 2;
3426 lodirty = bd->bd_lodirtybuffers;
3427 while (bd->bd_numdirtybuffers > lodirty) {
3428 if (buf_flush(NULL, bd,
3429 bd->bd_numdirtybuffers - lodirty) == 0)
3431 kern_yield(PRI_USER);
3436 * Only clear bd_request if we have reached our low water
3437 * mark. The buf_daemon normally waits 1 second and
3438 * then incrementally flushes any dirty buffers that have
3439 * built up, within reason.
3441 * If we were unable to hit our low water mark and couldn't
3442 * find any flushable buffers, we sleep for a short period
3443 * to avoid endless loops on unlockable buffers.
3446 if (!BIT_EMPTY(BUF_DOMAINS, &bdlodirty)) {
3448 * We reached our low water mark, reset the
3449 * request and sleep until we are needed again.
3450 * The sleep is just so the suspend code works.
3454 * Do an extra wakeup in case dirty threshold
3455 * changed via sysctl and the explicit transition
3456 * out of shortfall was missed.
3459 if (runningbufspace <= lorunningspace)
3461 msleep(&bd_request, &bdlock, PVM, "psleep", hz);
3464 * We couldn't find any flushable dirty buffers but
3465 * still have too many dirty buffers, we
3466 * have to sleep and try again. (rare)
3468 msleep(&bd_request, &bdlock, PVM, "qsleep", hz / 10);
3476 * Try to flush a buffer in the dirty queue. We must be careful to
3477 * free up B_INVAL buffers instead of write them, which NFS is
3478 * particularly sensitive to.
3480 static int flushwithdeps = 0;
3481 SYSCTL_INT(_vfs, OID_AUTO, flushwithdeps, CTLFLAG_RW | CTLFLAG_STATS,
3483 "Number of buffers flushed with dependecies that require rollbacks");
3486 flushbufqueues(struct vnode *lvp, struct bufdomain *bd, int target,
3489 struct bufqueue *bq;
3490 struct buf *sentinel;
3500 bq = &bd->bd_dirtyq;
3502 sentinel = malloc(sizeof(struct buf), M_TEMP, M_WAITOK | M_ZERO);
3503 sentinel->b_qindex = QUEUE_SENTINEL;
3505 TAILQ_INSERT_HEAD(&bq->bq_queue, sentinel, b_freelist);
3507 while (flushed != target) {
3510 bp = TAILQ_NEXT(sentinel, b_freelist);
3512 TAILQ_REMOVE(&bq->bq_queue, sentinel, b_freelist);
3513 TAILQ_INSERT_AFTER(&bq->bq_queue, bp, sentinel,
3520 * Skip sentinels inserted by other invocations of the
3521 * flushbufqueues(), taking care to not reorder them.
3523 * Only flush the buffers that belong to the
3524 * vnode locked by the curthread.
3526 if (bp->b_qindex == QUEUE_SENTINEL || (lvp != NULL &&
3531 error = BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL);
3537 * BKGRDINPROG can only be set with the buf and bufobj
3538 * locks both held. We tolerate a race to clear it here.
3540 if ((bp->b_vflags & BV_BKGRDINPROG) != 0 ||
3541 (bp->b_flags & B_DELWRI) == 0) {
3545 if (bp->b_flags & B_INVAL) {
3552 if (!LIST_EMPTY(&bp->b_dep) && buf_countdeps(bp, 0)) {
3553 if (flushdeps == 0) {
3561 * We must hold the lock on a vnode before writing
3562 * one of its buffers. Otherwise we may confuse, or
3563 * in the case of a snapshot vnode, deadlock the
3566 * The lock order here is the reverse of the normal
3567 * of vnode followed by buf lock. This is ok because
3568 * the NOWAIT will prevent deadlock.
3571 if (vn_start_write(vp, &mp, V_NOWAIT) != 0) {
3577 error = vn_lock(vp, LK_EXCLUSIVE | LK_NOWAIT);
3579 ASSERT_VOP_LOCKED(vp, "getbuf");
3581 error = VOP_ISLOCKED(vp) == LK_EXCLUSIVE ? 0 :
3582 vn_lock(vp, LK_TRYUPGRADE);
3585 CTR3(KTR_BUF, "flushbufqueue(%p) vp %p flags %X",
3586 bp, bp->b_vp, bp->b_flags);
3587 if (curproc == bufdaemonproc) {
3592 counter_u64_add(notbufdflushes, 1);
3594 vn_finished_write(mp);
3597 flushwithdeps += hasdeps;
3601 * Sleeping on runningbufspace while holding
3602 * vnode lock leads to deadlock.
3604 if (curproc == bufdaemonproc &&
3605 runningbufspace > hirunningspace)
3606 waitrunningbufspace();
3609 vn_finished_write(mp);
3613 TAILQ_REMOVE(&bq->bq_queue, sentinel, b_freelist);
3615 free(sentinel, M_TEMP);
3620 * Check to see if a block is currently memory resident.
3623 incore(struct bufobj *bo, daddr_t blkno)
3625 return (gbincore_unlocked(bo, blkno));
3629 * Returns true if no I/O is needed to access the
3630 * associated VM object. This is like incore except
3631 * it also hunts around in the VM system for the data.
3634 inmem(struct vnode * vp, daddr_t blkno)
3637 vm_offset_t toff, tinc, size;
3642 ASSERT_VOP_LOCKED(vp, "inmem");
3644 if (incore(&vp->v_bufobj, blkno))
3646 if (vp->v_mount == NULL)
3653 if (size > vp->v_mount->mnt_stat.f_iosize)
3654 size = vp->v_mount->mnt_stat.f_iosize;
3655 off = (vm_ooffset_t)blkno * (vm_ooffset_t)vp->v_mount->mnt_stat.f_iosize;
3657 for (toff = 0; toff < vp->v_mount->mnt_stat.f_iosize; toff += tinc) {
3658 m = vm_page_lookup_unlocked(obj, OFF_TO_IDX(off + toff));
3664 if (tinc > PAGE_SIZE - ((toff + off) & PAGE_MASK))
3665 tinc = PAGE_SIZE - ((toff + off) & PAGE_MASK);
3667 * Consider page validity only if page mapping didn't change
3670 valid = vm_page_is_valid(m,
3671 (vm_offset_t)((toff + off) & PAGE_MASK), tinc);
3672 n = vm_page_lookup_unlocked(obj, OFF_TO_IDX(off + toff));
3684 * Set the dirty range for a buffer based on the status of the dirty
3685 * bits in the pages comprising the buffer. The range is limited
3686 * to the size of the buffer.
3688 * Tell the VM system that the pages associated with this buffer
3689 * are clean. This is used for delayed writes where the data is
3690 * going to go to disk eventually without additional VM intevention.
3692 * Note that while we only really need to clean through to b_bcount, we
3693 * just go ahead and clean through to b_bufsize.
3696 vfs_clean_pages_dirty_buf(struct buf *bp)
3698 vm_ooffset_t foff, noff, eoff;
3702 if ((bp->b_flags & B_VMIO) == 0 || bp->b_bufsize == 0)
3705 foff = bp->b_offset;
3706 KASSERT(bp->b_offset != NOOFFSET,
3707 ("vfs_clean_pages_dirty_buf: no buffer offset"));
3709 vfs_busy_pages_acquire(bp);
3710 vfs_setdirty_range(bp);
3711 for (i = 0; i < bp->b_npages; i++) {
3712 noff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK;
3714 if (eoff > bp->b_offset + bp->b_bufsize)
3715 eoff = bp->b_offset + bp->b_bufsize;
3717 vfs_page_set_validclean(bp, foff, m);
3718 /* vm_page_clear_dirty(m, foff & PAGE_MASK, eoff - foff); */
3721 vfs_busy_pages_release(bp);
3725 vfs_setdirty_range(struct buf *bp)
3727 vm_offset_t boffset;
3728 vm_offset_t eoffset;
3732 * test the pages to see if they have been modified directly
3733 * by users through the VM system.
3735 for (i = 0; i < bp->b_npages; i++)
3736 vm_page_test_dirty(bp->b_pages[i]);
3739 * Calculate the encompassing dirty range, boffset and eoffset,
3740 * (eoffset - boffset) bytes.
3743 for (i = 0; i < bp->b_npages; i++) {
3744 if (bp->b_pages[i]->dirty)
3747 boffset = (i << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK);
3749 for (i = bp->b_npages - 1; i >= 0; --i) {
3750 if (bp->b_pages[i]->dirty) {
3754 eoffset = ((i + 1) << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK);
3757 * Fit it to the buffer.
3760 if (eoffset > bp->b_bcount)
3761 eoffset = bp->b_bcount;
3764 * If we have a good dirty range, merge with the existing
3768 if (boffset < eoffset) {
3769 if (bp->b_dirtyoff > boffset)
3770 bp->b_dirtyoff = boffset;
3771 if (bp->b_dirtyend < eoffset)
3772 bp->b_dirtyend = eoffset;
3777 * Allocate the KVA mapping for an existing buffer.
3778 * If an unmapped buffer is provided but a mapped buffer is requested, take
3779 * also care to properly setup mappings between pages and KVA.
3782 bp_unmapped_get_kva(struct buf *bp, daddr_t blkno, int size, int gbflags)
3784 int bsize, maxsize, need_mapping, need_kva;
3787 need_mapping = bp->b_data == unmapped_buf &&
3788 (gbflags & GB_UNMAPPED) == 0;
3789 need_kva = bp->b_kvabase == unmapped_buf &&
3790 bp->b_data == unmapped_buf &&
3791 (gbflags & GB_KVAALLOC) != 0;
3792 if (!need_mapping && !need_kva)
3795 BUF_CHECK_UNMAPPED(bp);
3797 if (need_mapping && bp->b_kvabase != unmapped_buf) {
3799 * Buffer is not mapped, but the KVA was already
3800 * reserved at the time of the instantiation. Use the
3807 * Calculate the amount of the address space we would reserve
3808 * if the buffer was mapped.
3810 bsize = vn_isdisk(bp->b_vp) ? DEV_BSIZE : bp->b_bufobj->bo_bsize;
3811 KASSERT(bsize != 0, ("bsize == 0, check bo->bo_bsize"));
3812 offset = blkno * bsize;
3813 maxsize = size + (offset & PAGE_MASK);
3814 maxsize = imax(maxsize, bsize);
3816 while (bufkva_alloc(bp, maxsize, gbflags) != 0) {
3817 if ((gbflags & GB_NOWAIT_BD) != 0) {
3819 * XXXKIB: defragmentation cannot
3820 * succeed, not sure what else to do.
3822 panic("GB_NOWAIT_BD and GB_UNMAPPED %p", bp);
3824 counter_u64_add(mappingrestarts, 1);
3825 bufspace_wait(bufdomain(bp), bp->b_vp, gbflags, 0, 0);
3829 /* b_offset is handled by bpmap_qenter. */
3830 bp->b_data = bp->b_kvabase;
3831 BUF_CHECK_MAPPED(bp);
3837 getblk(struct vnode *vp, daddr_t blkno, int size, int slpflag, int slptimeo,
3843 error = getblkx(vp, blkno, blkno, size, slpflag, slptimeo, flags, &bp);
3852 * Get a block given a specified block and offset into a file/device.
3853 * The buffers B_DONE bit will be cleared on return, making it almost
3854 * ready for an I/O initiation. B_INVAL may or may not be set on
3855 * return. The caller should clear B_INVAL prior to initiating a
3858 * For a non-VMIO buffer, B_CACHE is set to the opposite of B_INVAL for
3859 * an existing buffer.
3861 * For a VMIO buffer, B_CACHE is modified according to the backing VM.
3862 * If getblk()ing a previously 0-sized invalid buffer, B_CACHE is set
3863 * and then cleared based on the backing VM. If the previous buffer is
3864 * non-0-sized but invalid, B_CACHE will be cleared.
3866 * If getblk() must create a new buffer, the new buffer is returned with
3867 * both B_INVAL and B_CACHE clear unless it is a VMIO buffer, in which
3868 * case it is returned with B_INVAL clear and B_CACHE set based on the
3871 * getblk() also forces a bwrite() for any B_DELWRI buffer whose
3872 * B_CACHE bit is clear.
3874 * What this means, basically, is that the caller should use B_CACHE to
3875 * determine whether the buffer is fully valid or not and should clear
3876 * B_INVAL prior to issuing a read. If the caller intends to validate
3877 * the buffer by loading its data area with something, the caller needs
3878 * to clear B_INVAL. If the caller does this without issuing an I/O,
3879 * the caller should set B_CACHE ( as an optimization ), else the caller
3880 * should issue the I/O and biodone() will set B_CACHE if the I/O was
3881 * a write attempt or if it was a successful read. If the caller
3882 * intends to issue a READ, the caller must clear B_INVAL and BIO_ERROR
3883 * prior to issuing the READ. biodone() will *not* clear B_INVAL.
3885 * The blkno parameter is the logical block being requested. Normally
3886 * the mapping of logical block number to disk block address is done
3887 * by calling VOP_BMAP(). However, if the mapping is already known, the
3888 * disk block address can be passed using the dblkno parameter. If the
3889 * disk block address is not known, then the same value should be passed
3890 * for blkno and dblkno.
3893 getblkx(struct vnode *vp, daddr_t blkno, daddr_t dblkno, int size, int slpflag,
3894 int slptimeo, int flags, struct buf **bpp)
3899 int bsize, error, maxsize, vmio;
3902 CTR3(KTR_BUF, "getblk(%p, %ld, %d)", vp, (long)blkno, size);
3903 KASSERT((flags & (GB_UNMAPPED | GB_KVAALLOC)) != GB_KVAALLOC,
3904 ("GB_KVAALLOC only makes sense with GB_UNMAPPED"));
3905 ASSERT_VOP_LOCKED(vp, "getblk");
3906 if (size > maxbcachebuf)
3907 panic("getblk: size(%d) > maxbcachebuf(%d)\n", size,
3909 if (!unmapped_buf_allowed)
3910 flags &= ~(GB_UNMAPPED | GB_KVAALLOC);
3915 /* Attempt lockless lookup first. */
3916 bp = gbincore_unlocked(bo, blkno);
3918 goto newbuf_unlocked;
3920 error = BUF_TIMELOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL, "getblku", 0,
3925 /* Verify buf identify has not changed since lookup. */
3926 if (bp->b_bufobj == bo && bp->b_lblkno == blkno)
3927 goto foundbuf_fastpath;
3929 /* It changed, fallback to locked lookup. */
3934 bp = gbincore(bo, blkno);
3939 * Buffer is in-core. If the buffer is not busy nor managed,
3940 * it must be on a queue.
3942 lockflags = LK_EXCLUSIVE | LK_INTERLOCK |
3943 ((flags & GB_LOCK_NOWAIT) ? LK_NOWAIT : LK_SLEEPFAIL);
3945 error = BUF_TIMELOCK(bp, lockflags,
3946 BO_LOCKPTR(bo), "getblk", slpflag, slptimeo);
3949 * If we slept and got the lock we have to restart in case
3950 * the buffer changed identities.
3952 if (error == ENOLCK)
3954 /* We timed out or were interrupted. */
3955 else if (error != 0)
3959 /* If recursed, assume caller knows the rules. */
3960 if (BUF_LOCKRECURSED(bp))
3964 * The buffer is locked. B_CACHE is cleared if the buffer is
3965 * invalid. Otherwise, for a non-VMIO buffer, B_CACHE is set
3966 * and for a VMIO buffer B_CACHE is adjusted according to the
3969 if (bp->b_flags & B_INVAL)
3970 bp->b_flags &= ~B_CACHE;
3971 else if ((bp->b_flags & (B_VMIO | B_INVAL)) == 0)
3972 bp->b_flags |= B_CACHE;
3973 if (bp->b_flags & B_MANAGED)
3974 MPASS(bp->b_qindex == QUEUE_NONE);
3979 * check for size inconsistencies for non-VMIO case.
3981 if (bp->b_bcount != size) {
3982 if ((bp->b_flags & B_VMIO) == 0 ||
3983 (size > bp->b_kvasize)) {
3984 if (bp->b_flags & B_DELWRI) {
3985 bp->b_flags |= B_NOCACHE;
3988 if (LIST_EMPTY(&bp->b_dep)) {
3989 bp->b_flags |= B_RELBUF;
3992 bp->b_flags |= B_NOCACHE;
4001 * Handle the case of unmapped buffer which should
4002 * become mapped, or the buffer for which KVA
4003 * reservation is requested.
4005 bp_unmapped_get_kva(bp, blkno, size, flags);
4008 * If the size is inconsistent in the VMIO case, we can resize
4009 * the buffer. This might lead to B_CACHE getting set or
4010 * cleared. If the size has not changed, B_CACHE remains
4011 * unchanged from its previous state.
4015 KASSERT(bp->b_offset != NOOFFSET,
4016 ("getblk: no buffer offset"));
4019 * A buffer with B_DELWRI set and B_CACHE clear must
4020 * be committed before we can return the buffer in
4021 * order to prevent the caller from issuing a read
4022 * ( due to B_CACHE not being set ) and overwriting
4025 * Most callers, including NFS and FFS, need this to
4026 * operate properly either because they assume they
4027 * can issue a read if B_CACHE is not set, or because
4028 * ( for example ) an uncached B_DELWRI might loop due
4029 * to softupdates re-dirtying the buffer. In the latter
4030 * case, B_CACHE is set after the first write completes,
4031 * preventing further loops.
4032 * NOTE! b*write() sets B_CACHE. If we cleared B_CACHE
4033 * above while extending the buffer, we cannot allow the
4034 * buffer to remain with B_CACHE set after the write
4035 * completes or it will represent a corrupt state. To
4036 * deal with this we set B_NOCACHE to scrap the buffer
4039 * We might be able to do something fancy, like setting
4040 * B_CACHE in bwrite() except if B_DELWRI is already set,
4041 * so the below call doesn't set B_CACHE, but that gets real
4042 * confusing. This is much easier.
4045 if ((bp->b_flags & (B_CACHE|B_DELWRI)) == B_DELWRI) {
4046 bp->b_flags |= B_NOCACHE;
4050 bp->b_flags &= ~B_DONE;
4053 * Buffer is not in-core, create new buffer. The buffer
4054 * returned by getnewbuf() is locked. Note that the returned
4055 * buffer is also considered valid (not marked B_INVAL).
4060 * If the user does not want us to create the buffer, bail out
4063 if (flags & GB_NOCREAT)
4066 bsize = vn_isdisk(vp) ? DEV_BSIZE : bo->bo_bsize;
4067 KASSERT(bsize != 0, ("bsize == 0, check bo->bo_bsize"));
4068 offset = blkno * bsize;
4069 vmio = vp->v_object != NULL;
4071 maxsize = size + (offset & PAGE_MASK);
4074 /* Do not allow non-VMIO notmapped buffers. */
4075 flags &= ~(GB_UNMAPPED | GB_KVAALLOC);
4077 maxsize = imax(maxsize, bsize);
4078 if ((flags & GB_NOSPARSE) != 0 && vmio &&
4080 error = VOP_BMAP(vp, blkno, NULL, &d_blkno, 0, 0);
4081 KASSERT(error != EOPNOTSUPP,
4082 ("GB_NOSPARSE from fs not supporting bmap, vp %p",
4087 return (EJUSTRETURN);
4090 bp = getnewbuf(vp, slpflag, slptimeo, maxsize, flags);
4092 if (slpflag || slptimeo)
4095 * XXX This is here until the sleep path is diagnosed
4096 * enough to work under very low memory conditions.
4098 * There's an issue on low memory, 4BSD+non-preempt
4099 * systems (eg MIPS routers with 32MB RAM) where buffer
4100 * exhaustion occurs without sleeping for buffer
4101 * reclaimation. This just sticks in a loop and
4102 * constantly attempts to allocate a buffer, which
4103 * hits exhaustion and tries to wakeup bufdaemon.
4104 * This never happens because we never yield.
4106 * The real solution is to identify and fix these cases
4107 * so we aren't effectively busy-waiting in a loop
4108 * until the reclaimation path has cycles to run.
4110 kern_yield(PRI_USER);
4115 * This code is used to make sure that a buffer is not
4116 * created while the getnewbuf routine is blocked.
4117 * This can be a problem whether the vnode is locked or not.
4118 * If the buffer is created out from under us, we have to
4119 * throw away the one we just created.
4121 * Note: this must occur before we associate the buffer
4122 * with the vp especially considering limitations in
4123 * the splay tree implementation when dealing with duplicate
4127 if (gbincore(bo, blkno)) {
4129 bp->b_flags |= B_INVAL;
4130 bufspace_release(bufdomain(bp), maxsize);
4136 * Insert the buffer into the hash, so that it can
4137 * be found by incore.
4139 bp->b_lblkno = blkno;
4140 bp->b_blkno = d_blkno;
4141 bp->b_offset = offset;
4146 * set B_VMIO bit. allocbuf() the buffer bigger. Since the
4147 * buffer size starts out as 0, B_CACHE will be set by
4148 * allocbuf() for the VMIO case prior to it testing the
4149 * backing store for validity.
4153 bp->b_flags |= B_VMIO;
4154 KASSERT(vp->v_object == bp->b_bufobj->bo_object,
4155 ("ARGH! different b_bufobj->bo_object %p %p %p\n",
4156 bp, vp->v_object, bp->b_bufobj->bo_object));
4158 bp->b_flags &= ~B_VMIO;
4159 KASSERT(bp->b_bufobj->bo_object == NULL,
4160 ("ARGH! has b_bufobj->bo_object %p %p\n",
4161 bp, bp->b_bufobj->bo_object));
4162 BUF_CHECK_MAPPED(bp);
4166 bufspace_release(bufdomain(bp), maxsize);
4167 bp->b_flags &= ~B_DONE;
4169 CTR4(KTR_BUF, "getblk(%p, %ld, %d) = %p", vp, (long)blkno, size, bp);
4171 buf_track(bp, __func__);
4172 KASSERT(bp->b_bufobj == bo,
4173 ("bp %p wrong b_bufobj %p should be %p", bp, bp->b_bufobj, bo));
4179 * Get an empty, disassociated buffer of given size. The buffer is initially
4183 geteblk(int size, int flags)
4188 maxsize = (size + BKVAMASK) & ~BKVAMASK;
4189 while ((bp = getnewbuf(NULL, 0, 0, maxsize, flags)) == NULL) {
4190 if ((flags & GB_NOWAIT_BD) &&
4191 (curthread->td_pflags & TDP_BUFNEED) != 0)
4195 bufspace_release(bufdomain(bp), maxsize);
4196 bp->b_flags |= B_INVAL; /* b_dep cleared by getnewbuf() */
4201 * Truncate the backing store for a non-vmio buffer.
4204 vfs_nonvmio_truncate(struct buf *bp, int newbsize)
4207 if (bp->b_flags & B_MALLOC) {
4209 * malloced buffers are not shrunk
4211 if (newbsize == 0) {
4212 bufmallocadjust(bp, 0);
4213 free(bp->b_data, M_BIOBUF);
4214 bp->b_data = bp->b_kvabase;
4215 bp->b_flags &= ~B_MALLOC;
4219 vm_hold_free_pages(bp, newbsize);
4220 bufspace_adjust(bp, newbsize);
4224 * Extend the backing for a non-VMIO buffer.
4227 vfs_nonvmio_extend(struct buf *bp, int newbsize)
4233 * We only use malloced memory on the first allocation.
4234 * and revert to page-allocated memory when the buffer
4237 * There is a potential smp race here that could lead
4238 * to bufmallocspace slightly passing the max. It
4239 * is probably extremely rare and not worth worrying
4242 if (bp->b_bufsize == 0 && newbsize <= PAGE_SIZE/2 &&
4243 bufmallocspace < maxbufmallocspace) {
4244 bp->b_data = malloc(newbsize, M_BIOBUF, M_WAITOK);
4245 bp->b_flags |= B_MALLOC;
4246 bufmallocadjust(bp, newbsize);
4251 * If the buffer is growing on its other-than-first
4252 * allocation then we revert to the page-allocation
4257 if (bp->b_flags & B_MALLOC) {
4258 origbuf = bp->b_data;
4259 origbufsize = bp->b_bufsize;
4260 bp->b_data = bp->b_kvabase;
4261 bufmallocadjust(bp, 0);
4262 bp->b_flags &= ~B_MALLOC;
4263 newbsize = round_page(newbsize);
4265 vm_hold_load_pages(bp, (vm_offset_t) bp->b_data + bp->b_bufsize,
4266 (vm_offset_t) bp->b_data + newbsize);
4267 if (origbuf != NULL) {
4268 bcopy(origbuf, bp->b_data, origbufsize);
4269 free(origbuf, M_BIOBUF);
4271 bufspace_adjust(bp, newbsize);
4275 * This code constitutes the buffer memory from either anonymous system
4276 * memory (in the case of non-VMIO operations) or from an associated
4277 * VM object (in the case of VMIO operations). This code is able to
4278 * resize a buffer up or down.
4280 * Note that this code is tricky, and has many complications to resolve
4281 * deadlock or inconsistent data situations. Tread lightly!!!
4282 * There are B_CACHE and B_DELWRI interactions that must be dealt with by
4283 * the caller. Calling this code willy nilly can result in the loss of data.
4285 * allocbuf() only adjusts B_CACHE for VMIO buffers. getblk() deals with
4286 * B_CACHE for the non-VMIO case.
4289 allocbuf(struct buf *bp, int size)
4293 if (bp->b_bcount == size)
4296 if (bp->b_kvasize != 0 && bp->b_kvasize < size)
4297 panic("allocbuf: buffer too small");
4299 newbsize = roundup2(size, DEV_BSIZE);
4300 if ((bp->b_flags & B_VMIO) == 0) {
4301 if ((bp->b_flags & B_MALLOC) == 0)
4302 newbsize = round_page(newbsize);
4304 * Just get anonymous memory from the kernel. Don't
4305 * mess with B_CACHE.
4307 if (newbsize < bp->b_bufsize)
4308 vfs_nonvmio_truncate(bp, newbsize);
4309 else if (newbsize > bp->b_bufsize)
4310 vfs_nonvmio_extend(bp, newbsize);
4314 desiredpages = (size == 0) ? 0 :
4315 num_pages((bp->b_offset & PAGE_MASK) + newbsize);
4317 if (bp->b_flags & B_MALLOC)
4318 panic("allocbuf: VMIO buffer can't be malloced");
4320 * Set B_CACHE initially if buffer is 0 length or will become
4323 if (size == 0 || bp->b_bufsize == 0)
4324 bp->b_flags |= B_CACHE;
4326 if (newbsize < bp->b_bufsize)
4327 vfs_vmio_truncate(bp, desiredpages);
4328 /* XXX This looks as if it should be newbsize > b_bufsize */
4329 else if (size > bp->b_bcount)
4330 vfs_vmio_extend(bp, desiredpages, size);
4331 bufspace_adjust(bp, newbsize);
4333 bp->b_bcount = size; /* requested buffer size. */
4337 extern int inflight_transient_maps;
4339 static struct bio_queue nondump_bios;
4342 biodone(struct bio *bp)
4345 void (*done)(struct bio *);
4346 vm_offset_t start, end;
4348 biotrack(bp, __func__);
4351 * Avoid completing I/O when dumping after a panic since that may
4352 * result in a deadlock in the filesystem or pager code. Note that
4353 * this doesn't affect dumps that were started manually since we aim
4354 * to keep the system usable after it has been resumed.
4356 if (__predict_false(dumping && SCHEDULER_STOPPED())) {
4357 TAILQ_INSERT_HEAD(&nondump_bios, bp, bio_queue);
4360 if ((bp->bio_flags & BIO_TRANSIENT_MAPPING) != 0) {
4361 bp->bio_flags &= ~BIO_TRANSIENT_MAPPING;
4362 bp->bio_flags |= BIO_UNMAPPED;
4363 start = trunc_page((vm_offset_t)bp->bio_data);
4364 end = round_page((vm_offset_t)bp->bio_data + bp->bio_length);
4365 bp->bio_data = unmapped_buf;
4366 pmap_qremove(start, atop(end - start));
4367 vmem_free(transient_arena, start, end - start);
4368 atomic_add_int(&inflight_transient_maps, -1);
4370 done = bp->bio_done;
4372 mtxp = mtx_pool_find(mtxpool_sleep, bp);
4374 bp->bio_flags |= BIO_DONE;
4382 * Wait for a BIO to finish.
4385 biowait(struct bio *bp, const char *wchan)
4389 mtxp = mtx_pool_find(mtxpool_sleep, bp);
4391 while ((bp->bio_flags & BIO_DONE) == 0)
4392 msleep(bp, mtxp, PRIBIO, wchan, 0);
4394 if (bp->bio_error != 0)
4395 return (bp->bio_error);
4396 if (!(bp->bio_flags & BIO_ERROR))
4402 biofinish(struct bio *bp, struct devstat *stat, int error)
4406 bp->bio_error = error;
4407 bp->bio_flags |= BIO_ERROR;
4410 devstat_end_transaction_bio(stat, bp);
4414 #if defined(BUF_TRACKING) || defined(FULL_BUF_TRACKING)
4416 biotrack_buf(struct bio *bp, const char *location)
4419 buf_track(bp->bio_track_bp, location);
4426 * Wait for buffer I/O completion, returning error status. The buffer
4427 * is left locked and B_DONE on return. B_EINTR is converted into an EINTR
4428 * error and cleared.
4431 bufwait(struct buf *bp)
4433 if (bp->b_iocmd == BIO_READ)
4434 bwait(bp, PRIBIO, "biord");
4436 bwait(bp, PRIBIO, "biowr");
4437 if (bp->b_flags & B_EINTR) {
4438 bp->b_flags &= ~B_EINTR;
4441 if (bp->b_ioflags & BIO_ERROR) {
4442 return (bp->b_error ? bp->b_error : EIO);
4451 * Finish I/O on a buffer, optionally calling a completion function.
4452 * This is usually called from an interrupt so process blocking is
4455 * biodone is also responsible for setting B_CACHE in a B_VMIO bp.
4456 * In a non-VMIO bp, B_CACHE will be set on the next getblk()
4457 * assuming B_INVAL is clear.
4459 * For the VMIO case, we set B_CACHE if the op was a read and no
4460 * read error occurred, or if the op was a write. B_CACHE is never
4461 * set if the buffer is invalid or otherwise uncacheable.
4463 * bufdone does not mess with B_INVAL, allowing the I/O routine or the
4464 * initiator to leave B_INVAL set to brelse the buffer out of existence
4465 * in the biodone routine.
4468 bufdone(struct buf *bp)
4470 struct bufobj *dropobj;
4471 void (*biodone)(struct buf *);
4473 buf_track(bp, __func__);
4474 CTR3(KTR_BUF, "bufdone(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
4477 KASSERT(!(bp->b_flags & B_DONE), ("biodone: bp %p already done", bp));
4479 runningbufwakeup(bp);
4480 if (bp->b_iocmd == BIO_WRITE)
4481 dropobj = bp->b_bufobj;
4482 /* call optional completion function if requested */
4483 if (bp->b_iodone != NULL) {
4484 biodone = bp->b_iodone;
4485 bp->b_iodone = NULL;
4488 bufobj_wdrop(dropobj);
4491 if (bp->b_flags & B_VMIO) {
4493 * Set B_CACHE if the op was a normal read and no error
4494 * occurred. B_CACHE is set for writes in the b*write()
4497 if (bp->b_iocmd == BIO_READ &&
4498 !(bp->b_flags & (B_INVAL|B_NOCACHE)) &&
4499 !(bp->b_ioflags & BIO_ERROR))
4500 bp->b_flags |= B_CACHE;
4501 vfs_vmio_iodone(bp);
4503 if (!LIST_EMPTY(&bp->b_dep))
4505 if ((bp->b_flags & B_CKHASH) != 0) {
4506 KASSERT(bp->b_iocmd == BIO_READ,
4507 ("bufdone: b_iocmd %d not BIO_READ", bp->b_iocmd));
4508 KASSERT(buf_mapped(bp), ("bufdone: bp %p not mapped", bp));
4509 (*bp->b_ckhashcalc)(bp);
4512 * For asynchronous completions, release the buffer now. The brelse
4513 * will do a wakeup there if necessary - so no need to do a wakeup
4514 * here in the async case. The sync case always needs to do a wakeup.
4516 if (bp->b_flags & B_ASYNC) {
4517 if ((bp->b_flags & (B_NOCACHE | B_INVAL | B_RELBUF)) ||
4518 (bp->b_ioflags & BIO_ERROR))
4525 bufobj_wdrop(dropobj);
4529 * This routine is called in lieu of iodone in the case of
4530 * incomplete I/O. This keeps the busy status for pages
4534 vfs_unbusy_pages(struct buf *bp)
4540 runningbufwakeup(bp);
4541 if (!(bp->b_flags & B_VMIO))
4544 obj = bp->b_bufobj->bo_object;
4545 for (i = 0; i < bp->b_npages; i++) {
4547 if (m == bogus_page) {
4548 m = vm_page_relookup(obj, OFF_TO_IDX(bp->b_offset) + i);
4550 panic("vfs_unbusy_pages: page missing\n");
4552 if (buf_mapped(bp)) {
4553 BUF_CHECK_MAPPED(bp);
4554 pmap_qenter(trunc_page((vm_offset_t)bp->b_data),
4555 bp->b_pages, bp->b_npages);
4557 BUF_CHECK_UNMAPPED(bp);
4561 vm_object_pip_wakeupn(obj, bp->b_npages);
4565 * vfs_page_set_valid:
4567 * Set the valid bits in a page based on the supplied offset. The
4568 * range is restricted to the buffer's size.
4570 * This routine is typically called after a read completes.
4573 vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, vm_page_t m)
4578 * Compute the end offset, eoff, such that [off, eoff) does not span a
4579 * page boundary and eoff is not greater than the end of the buffer.
4580 * The end of the buffer, in this case, is our file EOF, not the
4581 * allocation size of the buffer.
4583 eoff = (off + PAGE_SIZE) & ~(vm_ooffset_t)PAGE_MASK;
4584 if (eoff > bp->b_offset + bp->b_bcount)
4585 eoff = bp->b_offset + bp->b_bcount;
4588 * Set valid range. This is typically the entire buffer and thus the
4592 vm_page_set_valid_range(m, off & PAGE_MASK, eoff - off);
4596 * vfs_page_set_validclean:
4598 * Set the valid bits and clear the dirty bits in a page based on the
4599 * supplied offset. The range is restricted to the buffer's size.
4602 vfs_page_set_validclean(struct buf *bp, vm_ooffset_t off, vm_page_t m)
4604 vm_ooffset_t soff, eoff;
4607 * Start and end offsets in buffer. eoff - soff may not cross a
4608 * page boundary or cross the end of the buffer. The end of the
4609 * buffer, in this case, is our file EOF, not the allocation size
4613 eoff = (off + PAGE_SIZE) & ~(off_t)PAGE_MASK;
4614 if (eoff > bp->b_offset + bp->b_bcount)
4615 eoff = bp->b_offset + bp->b_bcount;
4618 * Set valid range. This is typically the entire buffer and thus the
4622 vm_page_set_validclean(
4624 (vm_offset_t) (soff & PAGE_MASK),
4625 (vm_offset_t) (eoff - soff)
4631 * Acquire a shared busy on all pages in the buf.
4634 vfs_busy_pages_acquire(struct buf *bp)
4638 for (i = 0; i < bp->b_npages; i++)
4639 vm_page_busy_acquire(bp->b_pages[i], VM_ALLOC_SBUSY);
4643 vfs_busy_pages_release(struct buf *bp)
4647 for (i = 0; i < bp->b_npages; i++)
4648 vm_page_sunbusy(bp->b_pages[i]);
4652 * This routine is called before a device strategy routine.
4653 * It is used to tell the VM system that paging I/O is in
4654 * progress, and treat the pages associated with the buffer
4655 * almost as being exclusive busy. Also the object paging_in_progress
4656 * flag is handled to make sure that the object doesn't become
4659 * Since I/O has not been initiated yet, certain buffer flags
4660 * such as BIO_ERROR or B_INVAL may be in an inconsistent state
4661 * and should be ignored.
4664 vfs_busy_pages(struct buf *bp, int clear_modify)
4672 if (!(bp->b_flags & B_VMIO))
4675 obj = bp->b_bufobj->bo_object;
4676 foff = bp->b_offset;
4677 KASSERT(bp->b_offset != NOOFFSET,
4678 ("vfs_busy_pages: no buffer offset"));
4679 if ((bp->b_flags & B_CLUSTER) == 0) {
4680 vm_object_pip_add(obj, bp->b_npages);
4681 vfs_busy_pages_acquire(bp);
4683 if (bp->b_bufsize != 0)
4684 vfs_setdirty_range(bp);
4686 for (i = 0; i < bp->b_npages; i++) {
4688 vm_page_assert_sbusied(m);
4691 * When readying a buffer for a read ( i.e
4692 * clear_modify == 0 ), it is important to do
4693 * bogus_page replacement for valid pages in
4694 * partially instantiated buffers. Partially
4695 * instantiated buffers can, in turn, occur when
4696 * reconstituting a buffer from its VM backing store
4697 * base. We only have to do this if B_CACHE is
4698 * clear ( which causes the I/O to occur in the
4699 * first place ). The replacement prevents the read
4700 * I/O from overwriting potentially dirty VM-backed
4701 * pages. XXX bogus page replacement is, uh, bogus.
4702 * It may not work properly with small-block devices.
4703 * We need to find a better way.
4706 pmap_remove_write(m);
4707 vfs_page_set_validclean(bp, foff, m);
4708 } else if (vm_page_all_valid(m) &&
4709 (bp->b_flags & B_CACHE) == 0) {
4710 bp->b_pages[i] = bogus_page;
4713 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK;
4715 if (bogus && buf_mapped(bp)) {
4716 BUF_CHECK_MAPPED(bp);
4717 pmap_qenter(trunc_page((vm_offset_t)bp->b_data),
4718 bp->b_pages, bp->b_npages);
4723 * vfs_bio_set_valid:
4725 * Set the range within the buffer to valid. The range is
4726 * relative to the beginning of the buffer, b_offset. Note that
4727 * b_offset itself may be offset from the beginning of the first
4731 vfs_bio_set_valid(struct buf *bp, int base, int size)
4736 if (!(bp->b_flags & B_VMIO))
4740 * Fixup base to be relative to beginning of first page.
4741 * Set initial n to be the maximum number of bytes in the
4742 * first page that can be validated.
4744 base += (bp->b_offset & PAGE_MASK);
4745 n = PAGE_SIZE - (base & PAGE_MASK);
4748 * Busy may not be strictly necessary here because the pages are
4749 * unlikely to be fully valid and the vnode lock will synchronize
4750 * their access via getpages. It is grabbed for consistency with
4751 * other page validation.
4753 vfs_busy_pages_acquire(bp);
4754 for (i = base / PAGE_SIZE; size > 0 && i < bp->b_npages; ++i) {
4758 vm_page_set_valid_range(m, base & PAGE_MASK, n);
4763 vfs_busy_pages_release(bp);
4769 * If the specified buffer is a non-VMIO buffer, clear the entire
4770 * buffer. If the specified buffer is a VMIO buffer, clear and
4771 * validate only the previously invalid portions of the buffer.
4772 * This routine essentially fakes an I/O, so we need to clear
4773 * BIO_ERROR and B_INVAL.
4775 * Note that while we only theoretically need to clear through b_bcount,
4776 * we go ahead and clear through b_bufsize.
4779 vfs_bio_clrbuf(struct buf *bp)
4781 int i, j, mask, sa, ea, slide;
4783 if ((bp->b_flags & (B_VMIO | B_MALLOC)) != B_VMIO) {
4787 bp->b_flags &= ~B_INVAL;
4788 bp->b_ioflags &= ~BIO_ERROR;
4789 vfs_busy_pages_acquire(bp);
4790 sa = bp->b_offset & PAGE_MASK;
4792 for (i = 0; i < bp->b_npages; i++, sa = 0) {
4793 slide = imin(slide + PAGE_SIZE, bp->b_offset + bp->b_bufsize);
4794 ea = slide & PAGE_MASK;
4797 if (bp->b_pages[i] == bogus_page)
4800 mask = ((1 << ((ea - sa) / DEV_BSIZE)) - 1) << j;
4801 if ((bp->b_pages[i]->valid & mask) == mask)
4803 if ((bp->b_pages[i]->valid & mask) == 0)
4804 pmap_zero_page_area(bp->b_pages[i], sa, ea - sa);
4806 for (; sa < ea; sa += DEV_BSIZE, j++) {
4807 if ((bp->b_pages[i]->valid & (1 << j)) == 0) {
4808 pmap_zero_page_area(bp->b_pages[i],
4813 vm_page_set_valid_range(bp->b_pages[i], j * DEV_BSIZE,
4814 roundup2(ea - sa, DEV_BSIZE));
4816 vfs_busy_pages_release(bp);
4821 vfs_bio_bzero_buf(struct buf *bp, int base, int size)
4826 if (buf_mapped(bp)) {
4827 BUF_CHECK_MAPPED(bp);
4828 bzero(bp->b_data + base, size);
4830 BUF_CHECK_UNMAPPED(bp);
4831 n = PAGE_SIZE - (base & PAGE_MASK);
4832 for (i = base / PAGE_SIZE; size > 0 && i < bp->b_npages; ++i) {
4836 pmap_zero_page_area(m, base & PAGE_MASK, n);
4845 * Update buffer flags based on I/O request parameters, optionally releasing the
4846 * buffer. If it's VMIO or direct I/O, the buffer pages are released to the VM,
4847 * where they may be placed on a page queue (VMIO) or freed immediately (direct
4848 * I/O). Otherwise the buffer is released to the cache.
4851 b_io_dismiss(struct buf *bp, int ioflag, bool release)
4854 KASSERT((ioflag & IO_NOREUSE) == 0 || (ioflag & IO_VMIO) != 0,
4855 ("buf %p non-VMIO noreuse", bp));
4857 if ((ioflag & IO_DIRECT) != 0)
4858 bp->b_flags |= B_DIRECT;
4859 if ((ioflag & IO_EXT) != 0)
4860 bp->b_xflags |= BX_ALTDATA;
4861 if ((ioflag & (IO_VMIO | IO_DIRECT)) != 0 && LIST_EMPTY(&bp->b_dep)) {
4862 bp->b_flags |= B_RELBUF;
4863 if ((ioflag & IO_NOREUSE) != 0)
4864 bp->b_flags |= B_NOREUSE;
4872 vfs_bio_brelse(struct buf *bp, int ioflag)
4875 b_io_dismiss(bp, ioflag, true);
4879 vfs_bio_set_flags(struct buf *bp, int ioflag)
4882 b_io_dismiss(bp, ioflag, false);
4886 * vm_hold_load_pages and vm_hold_free_pages get pages into
4887 * a buffers address space. The pages are anonymous and are
4888 * not associated with a file object.
4891 vm_hold_load_pages(struct buf *bp, vm_offset_t from, vm_offset_t to)
4897 BUF_CHECK_MAPPED(bp);
4899 to = round_page(to);
4900 from = round_page(from);
4901 index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT;
4902 MPASS((bp->b_flags & B_MAXPHYS) == 0);
4903 KASSERT(to - from <= maxbcachebuf,
4904 ("vm_hold_load_pages too large %p %#jx %#jx %u",
4905 bp, (uintmax_t)from, (uintmax_t)to, maxbcachebuf));
4907 for (pg = from; pg < to; pg += PAGE_SIZE, index++) {
4909 * note: must allocate system pages since blocking here
4910 * could interfere with paging I/O, no matter which
4913 p = vm_page_alloc_noobj(VM_ALLOC_SYSTEM | VM_ALLOC_WIRED |
4914 VM_ALLOC_COUNT((to - pg) >> PAGE_SHIFT) | VM_ALLOC_WAITOK);
4915 pmap_qenter(pg, &p, 1);
4916 bp->b_pages[index] = p;
4918 bp->b_npages = index;
4921 /* Return pages associated with this buf to the vm system */
4923 vm_hold_free_pages(struct buf *bp, int newbsize)
4927 int index, newnpages;
4929 BUF_CHECK_MAPPED(bp);
4931 from = round_page((vm_offset_t)bp->b_data + newbsize);
4932 newnpages = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT;
4933 if (bp->b_npages > newnpages)
4934 pmap_qremove(from, bp->b_npages - newnpages);
4935 for (index = newnpages; index < bp->b_npages; index++) {
4936 p = bp->b_pages[index];
4937 bp->b_pages[index] = NULL;
4938 vm_page_unwire_noq(p);
4941 bp->b_npages = newnpages;
4945 * Map an IO request into kernel virtual address space.
4947 * All requests are (re)mapped into kernel VA space.
4948 * Notice that we use b_bufsize for the size of the buffer
4949 * to be mapped. b_bcount might be modified by the driver.
4951 * Note that even if the caller determines that the address space should
4952 * be valid, a race or a smaller-file mapped into a larger space may
4953 * actually cause vmapbuf() to fail, so all callers of vmapbuf() MUST
4954 * check the return value.
4956 * This function only works with pager buffers.
4959 vmapbuf(struct buf *bp, void *uaddr, size_t len, int mapbuf)
4964 MPASS((bp->b_flags & B_MAXPHYS) != 0);
4965 prot = VM_PROT_READ;
4966 if (bp->b_iocmd == BIO_READ)
4967 prot |= VM_PROT_WRITE; /* Less backwards than it looks */
4968 pidx = vm_fault_quick_hold_pages(&curproc->p_vmspace->vm_map,
4969 (vm_offset_t)uaddr, len, prot, bp->b_pages, PBUF_PAGES);
4972 bp->b_bufsize = len;
4973 bp->b_npages = pidx;
4974 bp->b_offset = ((vm_offset_t)uaddr) & PAGE_MASK;
4975 if (mapbuf || !unmapped_buf_allowed) {
4976 pmap_qenter((vm_offset_t)bp->b_kvabase, bp->b_pages, pidx);
4977 bp->b_data = bp->b_kvabase + bp->b_offset;
4979 bp->b_data = unmapped_buf;
4984 * Free the io map PTEs associated with this IO operation.
4985 * We also invalidate the TLB entries and restore the original b_addr.
4987 * This function only works with pager buffers.
4990 vunmapbuf(struct buf *bp)
4994 npages = bp->b_npages;
4996 pmap_qremove(trunc_page((vm_offset_t)bp->b_data), npages);
4997 vm_page_unhold_pages(bp->b_pages, npages);
4999 bp->b_data = unmapped_buf;
5003 bdone(struct buf *bp)
5007 mtxp = mtx_pool_find(mtxpool_sleep, bp);
5009 bp->b_flags |= B_DONE;
5015 bwait(struct buf *bp, u_char pri, const char *wchan)
5019 mtxp = mtx_pool_find(mtxpool_sleep, bp);
5021 while ((bp->b_flags & B_DONE) == 0)
5022 msleep(bp, mtxp, pri, wchan, 0);
5027 bufsync(struct bufobj *bo, int waitfor)
5030 return (VOP_FSYNC(bo2vnode(bo), waitfor, curthread));
5034 bufstrategy(struct bufobj *bo, struct buf *bp)
5040 KASSERT(vp == bo->bo_private, ("Inconsistent vnode bufstrategy"));
5041 KASSERT(vp->v_type != VCHR && vp->v_type != VBLK,
5042 ("Wrong vnode in bufstrategy(bp=%p, vp=%p)", bp, vp));
5043 i = VOP_STRATEGY(vp, bp);
5044 KASSERT(i == 0, ("VOP_STRATEGY failed bp=%p vp=%p", bp, bp->b_vp));
5048 * Initialize a struct bufobj before use. Memory is assumed zero filled.
5051 bufobj_init(struct bufobj *bo, void *private)
5053 static volatile int bufobj_cleanq;
5056 atomic_fetchadd_int(&bufobj_cleanq, 1) % buf_domains;
5057 rw_init(BO_LOCKPTR(bo), "bufobj interlock");
5058 bo->bo_private = private;
5059 TAILQ_INIT(&bo->bo_clean.bv_hd);
5060 TAILQ_INIT(&bo->bo_dirty.bv_hd);
5064 bufobj_wrefl(struct bufobj *bo)
5067 KASSERT(bo != NULL, ("NULL bo in bufobj_wref"));
5068 ASSERT_BO_WLOCKED(bo);
5073 bufobj_wref(struct bufobj *bo)
5076 KASSERT(bo != NULL, ("NULL bo in bufobj_wref"));
5083 bufobj_wdrop(struct bufobj *bo)
5086 KASSERT(bo != NULL, ("NULL bo in bufobj_wdrop"));
5088 KASSERT(bo->bo_numoutput > 0, ("bufobj_wdrop non-positive count"));
5089 if ((--bo->bo_numoutput == 0) && (bo->bo_flag & BO_WWAIT)) {
5090 bo->bo_flag &= ~BO_WWAIT;
5091 wakeup(&bo->bo_numoutput);
5097 bufobj_wwait(struct bufobj *bo, int slpflag, int timeo)
5101 KASSERT(bo != NULL, ("NULL bo in bufobj_wwait"));
5102 ASSERT_BO_WLOCKED(bo);
5104 while (bo->bo_numoutput) {
5105 bo->bo_flag |= BO_WWAIT;
5106 error = msleep(&bo->bo_numoutput, BO_LOCKPTR(bo),
5107 slpflag | (PRIBIO + 1), "bo_wwait", timeo);
5115 * Set bio_data or bio_ma for struct bio from the struct buf.
5118 bdata2bio(struct buf *bp, struct bio *bip)
5121 if (!buf_mapped(bp)) {
5122 KASSERT(unmapped_buf_allowed, ("unmapped"));
5123 bip->bio_ma = bp->b_pages;
5124 bip->bio_ma_n = bp->b_npages;
5125 bip->bio_data = unmapped_buf;
5126 bip->bio_ma_offset = (vm_offset_t)bp->b_offset & PAGE_MASK;
5127 bip->bio_flags |= BIO_UNMAPPED;
5128 KASSERT(round_page(bip->bio_ma_offset + bip->bio_length) /
5129 PAGE_SIZE == bp->b_npages,
5130 ("Buffer %p too short: %d %lld %d", bp, bip->bio_ma_offset,
5131 (long long)bip->bio_length, bip->bio_ma_n));
5133 bip->bio_data = bp->b_data;
5139 * The MIPS pmap code currently doesn't handle aliased pages.
5140 * The VIPT caches may not handle page aliasing themselves, leading
5141 * to data corruption.
5143 * As such, this code makes a system extremely unhappy if said
5144 * system doesn't support unaliasing the above situation in hardware.
5145 * Some "recent" systems (eg some mips24k/mips74k cores) don't enable
5146 * this feature at build time, so it has to be handled in software.
5148 * Once the MIPS pmap/cache code grows to support this function on
5149 * earlier chips, it should be flipped back off.
5152 static int buf_pager_relbuf = 1;
5154 static int buf_pager_relbuf = 0;
5156 SYSCTL_INT(_vfs, OID_AUTO, buf_pager_relbuf, CTLFLAG_RWTUN,
5157 &buf_pager_relbuf, 0,
5158 "Make buffer pager release buffers after reading");
5161 * The buffer pager. It uses buffer reads to validate pages.
5163 * In contrast to the generic local pager from vm/vnode_pager.c, this
5164 * pager correctly and easily handles volumes where the underlying
5165 * device block size is greater than the machine page size. The
5166 * buffer cache transparently extends the requested page run to be
5167 * aligned at the block boundary, and does the necessary bogus page
5168 * replacements in the addends to avoid obliterating already valid
5171 * The only non-trivial issue is that the exclusive busy state for
5172 * pages, which is assumed by the vm_pager_getpages() interface, is
5173 * incompatible with the VMIO buffer cache's desire to share-busy the
5174 * pages. This function performs a trivial downgrade of the pages'
5175 * state before reading buffers, and a less trivial upgrade from the
5176 * shared-busy to excl-busy state after the read.
5179 vfs_bio_getpages(struct vnode *vp, vm_page_t *ma, int count,
5180 int *rbehind, int *rahead, vbg_get_lblkno_t get_lblkno,
5181 vbg_get_blksize_t get_blksize)
5188 vm_ooffset_t la, lb, poff, poffe;
5190 int br_flags, error, i, pgsin, pgsin_a, pgsin_b;
5193 object = vp->v_object;
5196 la = IDX_TO_OFF(ma[count - 1]->pindex);
5197 if (la >= object->un_pager.vnp.vnp_size)
5198 return (VM_PAGER_BAD);
5201 * Change the meaning of la from where the last requested page starts
5202 * to where it ends, because that's the end of the requested region
5203 * and the start of the potential read-ahead region.
5206 lpart = la > object->un_pager.vnp.vnp_size;
5207 error = get_blksize(vp, get_lblkno(vp, IDX_TO_OFF(ma[0]->pindex)),
5210 return (VM_PAGER_ERROR);
5213 * Calculate read-ahead, behind and total pages.
5216 lb = IDX_TO_OFF(ma[0]->pindex);
5217 pgsin_b = OFF_TO_IDX(lb - rounddown2(lb, bo_bs));
5219 if (rbehind != NULL)
5221 pgsin_a = OFF_TO_IDX(roundup2(la, bo_bs) - la);
5222 if (la + IDX_TO_OFF(pgsin_a) >= object->un_pager.vnp.vnp_size)
5223 pgsin_a = OFF_TO_IDX(roundup2(object->un_pager.vnp.vnp_size,
5228 VM_CNT_INC(v_vnodein);
5229 VM_CNT_ADD(v_vnodepgsin, pgsin);
5231 br_flags = (mp != NULL && (mp->mnt_kern_flag & MNTK_UNMAPPED_BUFS)
5232 != 0) ? GB_UNMAPPED : 0;
5234 for (i = 0; i < count; i++) {
5235 if (ma[i] != bogus_page)
5236 vm_page_busy_downgrade(ma[i]);
5240 for (i = 0; i < count; i++) {
5242 if (m == bogus_page)
5246 * Pages are shared busy and the object lock is not
5247 * owned, which together allow for the pages'
5248 * invalidation. The racy test for validity avoids
5249 * useless creation of the buffer for the most typical
5250 * case when invalidation is not used in redo or for
5251 * parallel read. The shared->excl upgrade loop at
5252 * the end of the function catches the race in a
5253 * reliable way (protected by the object lock).
5255 if (vm_page_all_valid(m))
5258 poff = IDX_TO_OFF(m->pindex);
5259 poffe = MIN(poff + PAGE_SIZE, object->un_pager.vnp.vnp_size);
5260 for (; poff < poffe; poff += bsize) {
5261 lbn = get_lblkno(vp, poff);
5266 error = get_blksize(vp, lbn, &bsize);
5268 error = bread_gb(vp, lbn, bsize,
5269 curthread->td_ucred, br_flags, &bp);
5272 if (bp->b_rcred == curthread->td_ucred) {
5273 crfree(bp->b_rcred);
5274 bp->b_rcred = NOCRED;
5276 if (LIST_EMPTY(&bp->b_dep)) {
5278 * Invalidation clears m->valid, but
5279 * may leave B_CACHE flag if the
5280 * buffer existed at the invalidation
5281 * time. In this case, recycle the
5282 * buffer to do real read on next
5283 * bread() after redo.
5285 * Otherwise B_RELBUF is not strictly
5286 * necessary, enable to reduce buf
5289 if (buf_pager_relbuf ||
5290 !vm_page_all_valid(m))
5291 bp->b_flags |= B_RELBUF;
5293 bp->b_flags &= ~B_NOCACHE;
5299 KASSERT(1 /* racy, enable for debugging */ ||
5300 vm_page_all_valid(m) || i == count - 1,
5301 ("buf %d %p invalid", i, m));
5302 if (i == count - 1 && lpart) {
5303 if (!vm_page_none_valid(m) &&
5304 !vm_page_all_valid(m))
5305 vm_page_zero_invalid(m, TRUE);
5312 for (i = 0; i < count; i++) {
5313 if (ma[i] == bogus_page)
5315 if (vm_page_busy_tryupgrade(ma[i]) == 0) {
5316 vm_page_sunbusy(ma[i]);
5317 ma[i] = vm_page_grab_unlocked(object, ma[i]->pindex,
5322 * Since the pages were only sbusy while neither the
5323 * buffer nor the object lock was held by us, or
5324 * reallocated while vm_page_grab() slept for busy
5325 * relinguish, they could have been invalidated.
5326 * Recheck the valid bits and re-read as needed.
5328 * Note that the last page is made fully valid in the
5329 * read loop, and partial validity for the page at
5330 * index count - 1 could mean that the page was
5331 * invalidated or removed, so we must restart for
5334 if (!vm_page_all_valid(ma[i]))
5337 if (redo && error == 0)
5339 return (error != 0 ? VM_PAGER_ERROR : VM_PAGER_OK);
5342 #include "opt_ddb.h"
5344 #include <ddb/ddb.h>
5346 /* DDB command to show buffer data */
5347 DB_SHOW_COMMAND(buffer, db_show_buffer)
5350 struct buf *bp = (struct buf *)addr;
5351 #ifdef FULL_BUF_TRACKING
5356 db_printf("usage: show buffer <addr>\n");
5360 db_printf("buf at %p\n", bp);
5361 db_printf("b_flags = 0x%b, b_xflags=0x%b\n",
5362 (u_int)bp->b_flags, PRINT_BUF_FLAGS,
5363 (u_int)bp->b_xflags, PRINT_BUF_XFLAGS);
5364 db_printf("b_vflags=0x%b b_ioflags0x%b\n",
5365 (u_int)bp->b_vflags, PRINT_BUF_VFLAGS,
5366 (u_int)bp->b_ioflags, PRINT_BIO_FLAGS);
5368 "b_error = %d, b_bufsize = %ld, b_bcount = %ld, b_resid = %ld\n"
5369 "b_bufobj = (%p), b_data = %p\n, b_blkno = %jd, b_lblkno = %jd, "
5370 "b_vp = %p, b_dep = %p\n",
5371 bp->b_error, bp->b_bufsize, bp->b_bcount, bp->b_resid,
5372 bp->b_bufobj, bp->b_data, (intmax_t)bp->b_blkno,
5373 (intmax_t)bp->b_lblkno, bp->b_vp, bp->b_dep.lh_first);
5374 db_printf("b_kvabase = %p, b_kvasize = %d\n",
5375 bp->b_kvabase, bp->b_kvasize);
5378 db_printf("b_npages = %d, pages(OBJ, IDX, PA): ", bp->b_npages);
5379 for (i = 0; i < bp->b_npages; i++) {
5383 db_printf("(%p, 0x%lx, 0x%lx)", m->object,
5385 (u_long)VM_PAGE_TO_PHYS(m));
5387 db_printf("( ??? )");
5388 if ((i + 1) < bp->b_npages)
5393 BUF_LOCKPRINTINFO(bp);
5394 #if defined(FULL_BUF_TRACKING)
5395 db_printf("b_io_tracking: b_io_tcnt = %u\n", bp->b_io_tcnt);
5397 i = bp->b_io_tcnt % BUF_TRACKING_SIZE;
5398 for (j = 1; j <= BUF_TRACKING_SIZE; j++) {
5399 if (bp->b_io_tracking[BUF_TRACKING_ENTRY(i - j)] == NULL)
5401 db_printf(" %2u: %s\n", j,
5402 bp->b_io_tracking[BUF_TRACKING_ENTRY(i - j)]);
5404 #elif defined(BUF_TRACKING)
5405 db_printf("b_io_tracking: %s\n", bp->b_io_tracking);
5410 DB_SHOW_COMMAND(bufqueues, bufqueues)
5412 struct bufdomain *bd;
5417 db_printf("bqempty: %d\n", bqempty.bq_len);
5419 for (i = 0; i < buf_domains; i++) {
5421 db_printf("Buf domain %d\n", i);
5422 db_printf("\tfreebufs\t%d\n", bd->bd_freebuffers);
5423 db_printf("\tlofreebufs\t%d\n", bd->bd_lofreebuffers);
5424 db_printf("\thifreebufs\t%d\n", bd->bd_hifreebuffers);
5426 db_printf("\tbufspace\t%ld\n", bd->bd_bufspace);
5427 db_printf("\tmaxbufspace\t%ld\n", bd->bd_maxbufspace);
5428 db_printf("\thibufspace\t%ld\n", bd->bd_hibufspace);
5429 db_printf("\tlobufspace\t%ld\n", bd->bd_lobufspace);
5430 db_printf("\tbufspacethresh\t%ld\n", bd->bd_bufspacethresh);
5432 db_printf("\tnumdirtybuffers\t%d\n", bd->bd_numdirtybuffers);
5433 db_printf("\tlodirtybuffers\t%d\n", bd->bd_lodirtybuffers);
5434 db_printf("\thidirtybuffers\t%d\n", bd->bd_hidirtybuffers);
5435 db_printf("\tdirtybufthresh\t%d\n", bd->bd_dirtybufthresh);
5438 TAILQ_FOREACH(bp, &bd->bd_cleanq->bq_queue, b_freelist)
5439 total += bp->b_bufsize;
5440 db_printf("\tcleanq count\t%d (%ld)\n",
5441 bd->bd_cleanq->bq_len, total);
5443 TAILQ_FOREACH(bp, &bd->bd_dirtyq.bq_queue, b_freelist)
5444 total += bp->b_bufsize;
5445 db_printf("\tdirtyq count\t%d (%ld)\n",
5446 bd->bd_dirtyq.bq_len, total);
5447 db_printf("\twakeup\t\t%d\n", bd->bd_wanted);
5448 db_printf("\tlim\t\t%d\n", bd->bd_lim);
5449 db_printf("\tCPU ");
5450 for (j = 0; j <= mp_maxid; j++)
5451 db_printf("%d, ", bd->bd_subq[j].bq_len);
5455 for (j = 0; j < nbuf; j++) {
5457 if (bp->b_domain == i && BUF_ISLOCKED(bp)) {
5459 total += bp->b_bufsize;
5462 db_printf("\tLocked buffers: %d space %ld\n", cnt, total);
5465 for (j = 0; j < nbuf; j++) {
5467 if (bp->b_domain == i) {
5469 total += bp->b_bufsize;
5472 db_printf("\tTotal buffers: %d space %ld\n", cnt, total);
5476 DB_SHOW_COMMAND(lockedbufs, lockedbufs)
5481 for (i = 0; i < nbuf; i++) {
5483 if (BUF_ISLOCKED(bp)) {
5484 db_show_buffer((uintptr_t)bp, 1, 0, NULL);
5492 DB_SHOW_COMMAND(vnodebufs, db_show_vnodebufs)
5498 db_printf("usage: show vnodebufs <addr>\n");
5501 vp = (struct vnode *)addr;
5502 db_printf("Clean buffers:\n");
5503 TAILQ_FOREACH(bp, &vp->v_bufobj.bo_clean.bv_hd, b_bobufs) {
5504 db_show_buffer((uintptr_t)bp, 1, 0, NULL);
5507 db_printf("Dirty buffers:\n");
5508 TAILQ_FOREACH(bp, &vp->v_bufobj.bo_dirty.bv_hd, b_bobufs) {
5509 db_show_buffer((uintptr_t)bp, 1, 0, NULL);
5514 DB_COMMAND(countfreebufs, db_coundfreebufs)
5517 int i, used = 0, nfree = 0;
5520 db_printf("usage: countfreebufs\n");
5524 for (i = 0; i < nbuf; i++) {
5526 if (bp->b_qindex == QUEUE_EMPTY)
5532 db_printf("Counted %d free, %d used (%d tot)\n", nfree, used,
5534 db_printf("numfreebuffers is %d\n", numfreebuffers);