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>
53 #include <sys/bitset.h>
55 #include <sys/counter.h>
57 #include <sys/devicestat.h>
58 #include <sys/eventhandler.h>
61 #include <sys/limits.h>
63 #include <sys/malloc.h>
64 #include <sys/mount.h>
65 #include <sys/mutex.h>
66 #include <sys/kernel.h>
67 #include <sys/kthread.h>
69 #include <sys/racct.h>
70 #include <sys/refcount.h>
71 #include <sys/resourcevar.h>
72 #include <sys/rwlock.h>
74 #include <sys/sysctl.h>
75 #include <sys/syscallsubr.h>
77 #include <sys/vmmeter.h>
78 #include <sys/vnode.h>
79 #include <sys/watchdog.h>
80 #include <geom/geom.h>
82 #include <vm/vm_param.h>
83 #include <vm/vm_kern.h>
84 #include <vm/vm_object.h>
85 #include <vm/vm_page.h>
86 #include <vm/vm_pageout.h>
87 #include <vm/vm_pager.h>
88 #include <vm/vm_extern.h>
89 #include <vm/vm_map.h>
90 #include <vm/swap_pager.h>
92 static MALLOC_DEFINE(M_BIOBUF, "biobuf", "BIO buffer");
94 struct bio_ops bioops; /* I/O operation notification */
96 struct buf_ops buf_ops_bio = {
97 .bop_name = "buf_ops_bio",
98 .bop_write = bufwrite,
99 .bop_strategy = bufstrategy,
101 .bop_bdflush = bufbdflush,
105 struct mtx_padalign bq_lock;
106 TAILQ_HEAD(, buf) bq_queue;
108 uint16_t bq_subqueue;
110 } __aligned(CACHE_LINE_SIZE);
112 #define BQ_LOCKPTR(bq) (&(bq)->bq_lock)
113 #define BQ_LOCK(bq) mtx_lock(BQ_LOCKPTR((bq)))
114 #define BQ_UNLOCK(bq) mtx_unlock(BQ_LOCKPTR((bq)))
115 #define BQ_ASSERT_LOCKED(bq) mtx_assert(BQ_LOCKPTR((bq)), MA_OWNED)
118 struct bufqueue bd_subq[MAXCPU + 1]; /* Per-cpu sub queues + global */
119 struct bufqueue bd_dirtyq;
120 struct bufqueue *bd_cleanq;
121 struct mtx_padalign bd_run_lock;
126 long bd_bufspacethresh;
127 int bd_hifreebuffers;
128 int bd_lofreebuffers;
129 int bd_hidirtybuffers;
130 int bd_lodirtybuffers;
131 int bd_dirtybufthresh;
135 int __aligned(CACHE_LINE_SIZE) bd_numdirtybuffers;
136 int __aligned(CACHE_LINE_SIZE) bd_running;
137 long __aligned(CACHE_LINE_SIZE) bd_bufspace;
138 int __aligned(CACHE_LINE_SIZE) bd_freebuffers;
139 } __aligned(CACHE_LINE_SIZE);
141 #define BD_LOCKPTR(bd) (&(bd)->bd_cleanq->bq_lock)
142 #define BD_LOCK(bd) mtx_lock(BD_LOCKPTR((bd)))
143 #define BD_UNLOCK(bd) mtx_unlock(BD_LOCKPTR((bd)))
144 #define BD_ASSERT_LOCKED(bd) mtx_assert(BD_LOCKPTR((bd)), MA_OWNED)
145 #define BD_RUN_LOCKPTR(bd) (&(bd)->bd_run_lock)
146 #define BD_RUN_LOCK(bd) mtx_lock(BD_RUN_LOCKPTR((bd)))
147 #define BD_RUN_UNLOCK(bd) mtx_unlock(BD_RUN_LOCKPTR((bd)))
148 #define BD_DOMAIN(bd) (bd - bdomain)
150 static struct buf *buf; /* buffer header pool */
151 extern struct buf *swbuf; /* Swap buffer header pool. */
152 caddr_t __read_mostly unmapped_buf;
154 /* Used below and for softdep flushing threads in ufs/ffs/ffs_softdep.c */
155 struct proc *bufdaemonproc;
157 static int inmem(struct vnode *vp, daddr_t blkno);
158 static void vm_hold_free_pages(struct buf *bp, int newbsize);
159 static void vm_hold_load_pages(struct buf *bp, vm_offset_t from,
161 static void vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, vm_page_t m);
162 static void vfs_page_set_validclean(struct buf *bp, vm_ooffset_t off,
164 static void vfs_clean_pages_dirty_buf(struct buf *bp);
165 static void vfs_setdirty_range(struct buf *bp);
166 static void vfs_vmio_invalidate(struct buf *bp);
167 static void vfs_vmio_truncate(struct buf *bp, int npages);
168 static void vfs_vmio_extend(struct buf *bp, int npages, int size);
169 static int vfs_bio_clcheck(struct vnode *vp, int size,
170 daddr_t lblkno, daddr_t blkno);
171 static void breada(struct vnode *, daddr_t *, int *, int, struct ucred *, int,
172 void (*)(struct buf *));
173 static int buf_flush(struct vnode *vp, struct bufdomain *, int);
174 static int flushbufqueues(struct vnode *, struct bufdomain *, int, int);
175 static void buf_daemon(void);
176 static __inline void bd_wakeup(void);
177 static int sysctl_runningspace(SYSCTL_HANDLER_ARGS);
178 static void bufkva_reclaim(vmem_t *, int);
179 static void bufkva_free(struct buf *);
180 static int buf_import(void *, void **, int, int, int);
181 static void buf_release(void *, void **, int);
182 static void maxbcachebuf_adjust(void);
183 static inline struct bufdomain *bufdomain(struct buf *);
184 static void bq_remove(struct bufqueue *bq, struct buf *bp);
185 static void bq_insert(struct bufqueue *bq, struct buf *bp, bool unlock);
186 static int buf_recycle(struct bufdomain *, bool kva);
187 static void bq_init(struct bufqueue *bq, int qindex, int cpu,
188 const char *lockname);
189 static void bd_init(struct bufdomain *bd);
190 static int bd_flushall(struct bufdomain *bd);
191 static int sysctl_bufdomain_long(SYSCTL_HANDLER_ARGS);
192 static int sysctl_bufdomain_int(SYSCTL_HANDLER_ARGS);
194 static int sysctl_bufspace(SYSCTL_HANDLER_ARGS);
195 int vmiodirenable = TRUE;
196 SYSCTL_INT(_vfs, OID_AUTO, vmiodirenable, CTLFLAG_RW, &vmiodirenable, 0,
197 "Use the VM system for directory writes");
198 long runningbufspace;
199 SYSCTL_LONG(_vfs, OID_AUTO, runningbufspace, CTLFLAG_RD, &runningbufspace, 0,
200 "Amount of presently outstanding async buffer io");
201 SYSCTL_PROC(_vfs, OID_AUTO, bufspace, CTLTYPE_LONG|CTLFLAG_MPSAFE|CTLFLAG_RD,
202 NULL, 0, sysctl_bufspace, "L", "Physical memory used for buffers");
203 static counter_u64_t bufkvaspace;
204 SYSCTL_COUNTER_U64(_vfs, OID_AUTO, bufkvaspace, CTLFLAG_RD, &bufkvaspace,
205 "Kernel virtual memory used for buffers");
206 static long maxbufspace;
207 SYSCTL_PROC(_vfs, OID_AUTO, maxbufspace,
208 CTLTYPE_LONG|CTLFLAG_MPSAFE|CTLFLAG_RW, &maxbufspace,
209 __offsetof(struct bufdomain, bd_maxbufspace), sysctl_bufdomain_long, "L",
210 "Maximum allowed value of bufspace (including metadata)");
211 static long bufmallocspace;
212 SYSCTL_LONG(_vfs, OID_AUTO, bufmallocspace, CTLFLAG_RD, &bufmallocspace, 0,
213 "Amount of malloced memory for buffers");
214 static long maxbufmallocspace;
215 SYSCTL_LONG(_vfs, OID_AUTO, maxmallocbufspace, CTLFLAG_RW, &maxbufmallocspace,
216 0, "Maximum amount of malloced memory for buffers");
217 static long lobufspace;
218 SYSCTL_PROC(_vfs, OID_AUTO, lobufspace,
219 CTLTYPE_LONG|CTLFLAG_MPSAFE|CTLFLAG_RW, &lobufspace,
220 __offsetof(struct bufdomain, bd_lobufspace), sysctl_bufdomain_long, "L",
221 "Minimum amount of buffers we want to have");
223 SYSCTL_PROC(_vfs, OID_AUTO, hibufspace,
224 CTLTYPE_LONG|CTLFLAG_MPSAFE|CTLFLAG_RW, &hibufspace,
225 __offsetof(struct bufdomain, bd_hibufspace), sysctl_bufdomain_long, "L",
226 "Maximum allowed value of bufspace (excluding metadata)");
228 SYSCTL_PROC(_vfs, OID_AUTO, bufspacethresh,
229 CTLTYPE_LONG|CTLFLAG_MPSAFE|CTLFLAG_RW, &bufspacethresh,
230 __offsetof(struct bufdomain, bd_bufspacethresh), sysctl_bufdomain_long, "L",
231 "Bufspace consumed before waking the daemon to free some");
232 static counter_u64_t buffreekvacnt;
233 SYSCTL_COUNTER_U64(_vfs, OID_AUTO, buffreekvacnt, CTLFLAG_RW, &buffreekvacnt,
234 "Number of times we have freed the KVA space from some buffer");
235 static counter_u64_t bufdefragcnt;
236 SYSCTL_COUNTER_U64(_vfs, OID_AUTO, bufdefragcnt, CTLFLAG_RW, &bufdefragcnt,
237 "Number of times we have had to repeat buffer allocation to defragment");
238 static long lorunningspace;
239 SYSCTL_PROC(_vfs, OID_AUTO, lorunningspace, CTLTYPE_LONG | CTLFLAG_MPSAFE |
240 CTLFLAG_RW, &lorunningspace, 0, sysctl_runningspace, "L",
241 "Minimum preferred space used for in-progress I/O");
242 static long hirunningspace;
243 SYSCTL_PROC(_vfs, OID_AUTO, hirunningspace, CTLTYPE_LONG | CTLFLAG_MPSAFE |
244 CTLFLAG_RW, &hirunningspace, 0, sysctl_runningspace, "L",
245 "Maximum amount of space to use for in-progress I/O");
246 int dirtybufferflushes;
247 SYSCTL_INT(_vfs, OID_AUTO, dirtybufferflushes, CTLFLAG_RW, &dirtybufferflushes,
248 0, "Number of bdwrite to bawrite conversions to limit dirty buffers");
250 SYSCTL_INT(_vfs, OID_AUTO, bdwriteskip, CTLFLAG_RW, &bdwriteskip,
251 0, "Number of buffers supplied to bdwrite with snapshot deadlock risk");
252 int altbufferflushes;
253 SYSCTL_INT(_vfs, OID_AUTO, altbufferflushes, CTLFLAG_RW | CTLFLAG_STATS,
254 &altbufferflushes, 0, "Number of fsync flushes to limit dirty buffers");
255 static int recursiveflushes;
256 SYSCTL_INT(_vfs, OID_AUTO, recursiveflushes, CTLFLAG_RW | CTLFLAG_STATS,
257 &recursiveflushes, 0, "Number of flushes skipped due to being recursive");
258 static int sysctl_numdirtybuffers(SYSCTL_HANDLER_ARGS);
259 SYSCTL_PROC(_vfs, OID_AUTO, numdirtybuffers,
260 CTLTYPE_INT|CTLFLAG_MPSAFE|CTLFLAG_RD, NULL, 0, sysctl_numdirtybuffers, "I",
261 "Number of buffers that are dirty (has unwritten changes) at the moment");
262 static int lodirtybuffers;
263 SYSCTL_PROC(_vfs, OID_AUTO, lodirtybuffers,
264 CTLTYPE_INT|CTLFLAG_MPSAFE|CTLFLAG_RW, &lodirtybuffers,
265 __offsetof(struct bufdomain, bd_lodirtybuffers), sysctl_bufdomain_int, "I",
266 "How many buffers we want to have free before bufdaemon can sleep");
267 static int hidirtybuffers;
268 SYSCTL_PROC(_vfs, OID_AUTO, hidirtybuffers,
269 CTLTYPE_INT|CTLFLAG_MPSAFE|CTLFLAG_RW, &hidirtybuffers,
270 __offsetof(struct bufdomain, bd_hidirtybuffers), sysctl_bufdomain_int, "I",
271 "When the number of dirty buffers is considered severe");
273 SYSCTL_PROC(_vfs, OID_AUTO, dirtybufthresh,
274 CTLTYPE_INT|CTLFLAG_MPSAFE|CTLFLAG_RW, &dirtybufthresh,
275 __offsetof(struct bufdomain, bd_dirtybufthresh), sysctl_bufdomain_int, "I",
276 "Number of bdwrite to bawrite conversions to clear dirty buffers");
277 static int numfreebuffers;
278 SYSCTL_INT(_vfs, OID_AUTO, numfreebuffers, CTLFLAG_RD, &numfreebuffers, 0,
279 "Number of free buffers");
280 static int lofreebuffers;
281 SYSCTL_PROC(_vfs, OID_AUTO, lofreebuffers,
282 CTLTYPE_INT|CTLFLAG_MPSAFE|CTLFLAG_RW, &lofreebuffers,
283 __offsetof(struct bufdomain, bd_lofreebuffers), sysctl_bufdomain_int, "I",
284 "Target number of free buffers");
285 static int hifreebuffers;
286 SYSCTL_PROC(_vfs, OID_AUTO, hifreebuffers,
287 CTLTYPE_INT|CTLFLAG_MPSAFE|CTLFLAG_RW, &hifreebuffers,
288 __offsetof(struct bufdomain, bd_hifreebuffers), sysctl_bufdomain_int, "I",
289 "Threshold for clean buffer recycling");
290 static counter_u64_t getnewbufcalls;
291 SYSCTL_COUNTER_U64(_vfs, OID_AUTO, getnewbufcalls, CTLFLAG_RD,
292 &getnewbufcalls, "Number of calls to getnewbuf");
293 static counter_u64_t getnewbufrestarts;
294 SYSCTL_COUNTER_U64(_vfs, OID_AUTO, getnewbufrestarts, CTLFLAG_RD,
296 "Number of times getnewbuf has had to restart a buffer acquisition");
297 static counter_u64_t mappingrestarts;
298 SYSCTL_COUNTER_U64(_vfs, OID_AUTO, mappingrestarts, CTLFLAG_RD,
300 "Number of times getblk has had to restart a buffer mapping for "
302 static counter_u64_t numbufallocfails;
303 SYSCTL_COUNTER_U64(_vfs, OID_AUTO, numbufallocfails, CTLFLAG_RW,
304 &numbufallocfails, "Number of times buffer allocations failed");
305 static int flushbufqtarget = 100;
306 SYSCTL_INT(_vfs, OID_AUTO, flushbufqtarget, CTLFLAG_RW, &flushbufqtarget, 0,
307 "Amount of work to do in flushbufqueues when helping bufdaemon");
308 static counter_u64_t notbufdflushes;
309 SYSCTL_COUNTER_U64(_vfs, OID_AUTO, notbufdflushes, CTLFLAG_RD, ¬bufdflushes,
310 "Number of dirty buffer flushes done by the bufdaemon helpers");
311 static long barrierwrites;
312 SYSCTL_LONG(_vfs, OID_AUTO, barrierwrites, CTLFLAG_RW | CTLFLAG_STATS,
313 &barrierwrites, 0, "Number of barrier writes");
314 SYSCTL_INT(_vfs, OID_AUTO, unmapped_buf_allowed, CTLFLAG_RD,
315 &unmapped_buf_allowed, 0,
316 "Permit the use of the unmapped i/o");
317 int maxbcachebuf = MAXBCACHEBUF;
318 SYSCTL_INT(_vfs, OID_AUTO, maxbcachebuf, CTLFLAG_RDTUN, &maxbcachebuf, 0,
319 "Maximum size of a buffer cache block");
322 * This lock synchronizes access to bd_request.
324 static struct mtx_padalign __exclusive_cache_line bdlock;
327 * This lock protects the runningbufreq and synchronizes runningbufwakeup and
328 * waitrunningbufspace().
330 static struct mtx_padalign __exclusive_cache_line rbreqlock;
333 * Lock that protects bdirtywait.
335 static struct mtx_padalign __exclusive_cache_line bdirtylock;
338 * Wakeup point for bufdaemon, as well as indicator of whether it is already
339 * active. Set to 1 when the bufdaemon is already "on" the queue, 0 when it
342 static int bd_request;
345 * Request for the buf daemon to write more buffers than is indicated by
346 * lodirtybuf. This may be necessary to push out excess dependencies or
347 * defragment the address space where a simple count of the number of dirty
348 * buffers is insufficient to characterize the demand for flushing them.
350 static int bd_speedupreq;
353 * Synchronization (sleep/wakeup) variable for active buffer space requests.
354 * Set when wait starts, cleared prior to wakeup().
355 * Used in runningbufwakeup() and waitrunningbufspace().
357 static int runningbufreq;
360 * Synchronization for bwillwrite() waiters.
362 static int bdirtywait;
365 * Definitions for the buffer free lists.
367 #define QUEUE_NONE 0 /* on no queue */
368 #define QUEUE_EMPTY 1 /* empty buffer headers */
369 #define QUEUE_DIRTY 2 /* B_DELWRI buffers */
370 #define QUEUE_CLEAN 3 /* non-B_DELWRI buffers */
371 #define QUEUE_SENTINEL 4 /* not an queue index, but mark for sentinel */
373 /* Maximum number of buffer domains. */
374 #define BUF_DOMAINS 8
376 struct bufdomainset bdlodirty; /* Domains > lodirty */
377 struct bufdomainset bdhidirty; /* Domains > hidirty */
379 /* Configured number of clean queues. */
380 static int __read_mostly buf_domains;
382 BITSET_DEFINE(bufdomainset, BUF_DOMAINS);
383 struct bufdomain __exclusive_cache_line bdomain[BUF_DOMAINS];
384 struct bufqueue __exclusive_cache_line bqempty;
387 * per-cpu empty buffer cache.
392 * Single global constant for BUF_WMESG, to avoid getting multiple references.
393 * buf_wmesg is referred from macros.
395 const char *buf_wmesg = BUF_WMESG;
398 sysctl_runningspace(SYSCTL_HANDLER_ARGS)
403 value = *(long *)arg1;
404 error = sysctl_handle_long(oidp, &value, 0, req);
405 if (error != 0 || req->newptr == NULL)
407 mtx_lock(&rbreqlock);
408 if (arg1 == &hirunningspace) {
409 if (value < lorunningspace)
412 hirunningspace = value;
414 KASSERT(arg1 == &lorunningspace,
415 ("%s: unknown arg1", __func__));
416 if (value > hirunningspace)
419 lorunningspace = value;
421 mtx_unlock(&rbreqlock);
426 sysctl_bufdomain_int(SYSCTL_HANDLER_ARGS)
432 value = *(int *)arg1;
433 error = sysctl_handle_int(oidp, &value, 0, req);
434 if (error != 0 || req->newptr == NULL)
436 *(int *)arg1 = value;
437 for (i = 0; i < buf_domains; i++)
438 *(int *)(uintptr_t)(((uintptr_t)&bdomain[i]) + arg2) =
445 sysctl_bufdomain_long(SYSCTL_HANDLER_ARGS)
451 value = *(long *)arg1;
452 error = sysctl_handle_long(oidp, &value, 0, req);
453 if (error != 0 || req->newptr == NULL)
455 *(long *)arg1 = value;
456 for (i = 0; i < buf_domains; i++)
457 *(long *)(uintptr_t)(((uintptr_t)&bdomain[i]) + arg2) =
463 #if defined(COMPAT_FREEBSD4) || defined(COMPAT_FREEBSD5) || \
464 defined(COMPAT_FREEBSD6) || defined(COMPAT_FREEBSD7)
466 sysctl_bufspace(SYSCTL_HANDLER_ARGS)
473 for (i = 0; i < buf_domains; i++)
474 lvalue += bdomain[i].bd_bufspace;
475 if (sizeof(int) == sizeof(long) || req->oldlen >= sizeof(long))
476 return (sysctl_handle_long(oidp, &lvalue, 0, req));
477 if (lvalue > INT_MAX)
478 /* On overflow, still write out a long to trigger ENOMEM. */
479 return (sysctl_handle_long(oidp, &lvalue, 0, req));
481 return (sysctl_handle_int(oidp, &ivalue, 0, req));
485 sysctl_bufspace(SYSCTL_HANDLER_ARGS)
491 for (i = 0; i < buf_domains; i++)
492 lvalue += bdomain[i].bd_bufspace;
493 return (sysctl_handle_long(oidp, &lvalue, 0, req));
498 sysctl_numdirtybuffers(SYSCTL_HANDLER_ARGS)
504 for (i = 0; i < buf_domains; i++)
505 value += bdomain[i].bd_numdirtybuffers;
506 return (sysctl_handle_int(oidp, &value, 0, req));
512 * Wakeup any bwillwrite() waiters.
517 mtx_lock(&bdirtylock);
522 mtx_unlock(&bdirtylock);
528 * Clear a domain from the appropriate bitsets when dirtybuffers
532 bd_clear(struct bufdomain *bd)
535 mtx_lock(&bdirtylock);
536 if (bd->bd_numdirtybuffers <= bd->bd_lodirtybuffers)
537 BIT_CLR(BUF_DOMAINS, BD_DOMAIN(bd), &bdlodirty);
538 if (bd->bd_numdirtybuffers <= bd->bd_hidirtybuffers)
539 BIT_CLR(BUF_DOMAINS, BD_DOMAIN(bd), &bdhidirty);
540 mtx_unlock(&bdirtylock);
546 * Set a domain in the appropriate bitsets when dirtybuffers
550 bd_set(struct bufdomain *bd)
553 mtx_lock(&bdirtylock);
554 if (bd->bd_numdirtybuffers > bd->bd_lodirtybuffers)
555 BIT_SET(BUF_DOMAINS, BD_DOMAIN(bd), &bdlodirty);
556 if (bd->bd_numdirtybuffers > bd->bd_hidirtybuffers)
557 BIT_SET(BUF_DOMAINS, BD_DOMAIN(bd), &bdhidirty);
558 mtx_unlock(&bdirtylock);
564 * Decrement the numdirtybuffers count by one and wakeup any
565 * threads blocked in bwillwrite().
568 bdirtysub(struct buf *bp)
570 struct bufdomain *bd;
574 num = atomic_fetchadd_int(&bd->bd_numdirtybuffers, -1);
575 if (num == (bd->bd_lodirtybuffers + bd->bd_hidirtybuffers) / 2)
577 if (num == bd->bd_lodirtybuffers || num == bd->bd_hidirtybuffers)
584 * Increment the numdirtybuffers count by one and wakeup the buf
588 bdirtyadd(struct buf *bp)
590 struct bufdomain *bd;
594 * Only do the wakeup once as we cross the boundary. The
595 * buf daemon will keep running until the condition clears.
598 num = atomic_fetchadd_int(&bd->bd_numdirtybuffers, 1);
599 if (num == (bd->bd_lodirtybuffers + bd->bd_hidirtybuffers) / 2)
601 if (num == bd->bd_lodirtybuffers || num == bd->bd_hidirtybuffers)
606 * bufspace_daemon_wakeup:
608 * Wakeup the daemons responsible for freeing clean bufs.
611 bufspace_daemon_wakeup(struct bufdomain *bd)
615 * avoid the lock if the daemon is running.
617 if (atomic_fetchadd_int(&bd->bd_running, 1) == 0) {
619 atomic_store_int(&bd->bd_running, 1);
620 wakeup(&bd->bd_running);
626 * bufspace_daemon_wait:
628 * Sleep until the domain falls below a limit or one second passes.
631 bufspace_daemon_wait(struct bufdomain *bd)
634 * Re-check our limits and sleep. bd_running must be
635 * cleared prior to checking the limits to avoid missed
636 * wakeups. The waker will adjust one of bufspace or
637 * freebuffers prior to checking bd_running.
640 atomic_store_int(&bd->bd_running, 0);
641 if (bd->bd_bufspace < bd->bd_bufspacethresh &&
642 bd->bd_freebuffers > bd->bd_lofreebuffers) {
643 msleep(&bd->bd_running, BD_RUN_LOCKPTR(bd), PRIBIO|PDROP,
646 /* Avoid spurious wakeups while running. */
647 atomic_store_int(&bd->bd_running, 1);
655 * Adjust the reported bufspace for a KVA managed buffer, possibly
656 * waking any waiters.
659 bufspace_adjust(struct buf *bp, int bufsize)
661 struct bufdomain *bd;
665 KASSERT((bp->b_flags & B_MALLOC) == 0,
666 ("bufspace_adjust: malloc buf %p", bp));
668 diff = bufsize - bp->b_bufsize;
670 atomic_subtract_long(&bd->bd_bufspace, -diff);
671 } else if (diff > 0) {
672 space = atomic_fetchadd_long(&bd->bd_bufspace, diff);
673 /* Wake up the daemon on the transition. */
674 if (space < bd->bd_bufspacethresh &&
675 space + diff >= bd->bd_bufspacethresh)
676 bufspace_daemon_wakeup(bd);
678 bp->b_bufsize = bufsize;
684 * Reserve bufspace before calling allocbuf(). metadata has a
685 * different space limit than data.
688 bufspace_reserve(struct bufdomain *bd, int size, bool metadata)
694 limit = bd->bd_maxbufspace;
696 limit = bd->bd_hibufspace;
697 space = atomic_fetchadd_long(&bd->bd_bufspace, size);
700 atomic_subtract_long(&bd->bd_bufspace, size);
704 /* Wake up the daemon on the transition. */
705 if (space < bd->bd_bufspacethresh && new >= bd->bd_bufspacethresh)
706 bufspace_daemon_wakeup(bd);
714 * Release reserved bufspace after bufspace_adjust() has consumed it.
717 bufspace_release(struct bufdomain *bd, int size)
720 atomic_subtract_long(&bd->bd_bufspace, size);
726 * Wait for bufspace, acting as the buf daemon if a locked vnode is
727 * supplied. bd_wanted must be set prior to polling for space. The
728 * operation must be re-tried on return.
731 bufspace_wait(struct bufdomain *bd, struct vnode *vp, int gbflags,
732 int slpflag, int slptimeo)
735 int error, fl, norunbuf;
737 if ((gbflags & GB_NOWAIT_BD) != 0)
742 while (bd->bd_wanted) {
743 if (vp != NULL && vp->v_type != VCHR &&
744 (td->td_pflags & TDP_BUFNEED) == 0) {
747 * getblk() is called with a vnode locked, and
748 * some majority of the dirty buffers may as
749 * well belong to the vnode. Flushing the
750 * buffers there would make a progress that
751 * cannot be achieved by the buf_daemon, that
752 * cannot lock the vnode.
754 norunbuf = ~(TDP_BUFNEED | TDP_NORUNNINGBUF) |
755 (td->td_pflags & TDP_NORUNNINGBUF);
758 * Play bufdaemon. The getnewbuf() function
759 * may be called while the thread owns lock
760 * for another dirty buffer for the same
761 * vnode, which makes it impossible to use
762 * VOP_FSYNC() there, due to the buffer lock
765 td->td_pflags |= TDP_BUFNEED | TDP_NORUNNINGBUF;
766 fl = buf_flush(vp, bd, flushbufqtarget);
767 td->td_pflags &= norunbuf;
771 if (bd->bd_wanted == 0)
774 error = msleep(&bd->bd_wanted, BD_LOCKPTR(bd),
775 (PRIBIO + 4) | slpflag, "newbuf", slptimeo);
786 * buffer space management daemon. Tries to maintain some marginal
787 * amount of free buffer space so that requesting processes neither
788 * block nor work to reclaim buffers.
791 bufspace_daemon(void *arg)
793 struct bufdomain *bd;
795 EVENTHANDLER_REGISTER(shutdown_pre_sync, kthread_shutdown, curthread,
796 SHUTDOWN_PRI_LAST + 100);
800 kthread_suspend_check();
803 * Free buffers from the clean queue until we meet our
806 * Theory of operation: The buffer cache is most efficient
807 * when some free buffer headers and space are always
808 * available to getnewbuf(). This daemon attempts to prevent
809 * the excessive blocking and synchronization associated
810 * with shortfall. It goes through three phases according
813 * 1) The daemon wakes up voluntarily once per-second
814 * during idle periods when the counters are below
815 * the wakeup thresholds (bufspacethresh, lofreebuffers).
817 * 2) The daemon wakes up as we cross the thresholds
818 * ahead of any potential blocking. This may bounce
819 * slightly according to the rate of consumption and
822 * 3) The daemon and consumers are starved for working
823 * clean buffers. This is the 'bufspace' sleep below
824 * which will inefficiently trade bufs with bqrelse
825 * until we return to condition 2.
827 while (bd->bd_bufspace > bd->bd_lobufspace ||
828 bd->bd_freebuffers < bd->bd_hifreebuffers) {
829 if (buf_recycle(bd, false) != 0) {
833 * Speedup dirty if we've run out of clean
834 * buffers. This is possible in particular
835 * because softdep may held many bufs locked
836 * pending writes to other bufs which are
837 * marked for delayed write, exhausting
838 * clean space until they are written.
843 msleep(&bd->bd_wanted, BD_LOCKPTR(bd),
844 PRIBIO|PDROP, "bufspace", hz/10);
850 bufspace_daemon_wait(bd);
857 * Adjust the reported bufspace for a malloc managed buffer, possibly
858 * waking any waiters.
861 bufmallocadjust(struct buf *bp, int bufsize)
865 KASSERT((bp->b_flags & B_MALLOC) != 0,
866 ("bufmallocadjust: non-malloc buf %p", bp));
867 diff = bufsize - bp->b_bufsize;
869 atomic_subtract_long(&bufmallocspace, -diff);
871 atomic_add_long(&bufmallocspace, diff);
872 bp->b_bufsize = bufsize;
878 * Wake up processes that are waiting on asynchronous writes to fall
879 * below lorunningspace.
885 mtx_lock(&rbreqlock);
888 wakeup(&runningbufreq);
890 mtx_unlock(&rbreqlock);
896 * Decrement the outstanding write count according.
899 runningbufwakeup(struct buf *bp)
903 bspace = bp->b_runningbufspace;
906 space = atomic_fetchadd_long(&runningbufspace, -bspace);
907 KASSERT(space >= bspace, ("runningbufspace underflow %ld %ld",
909 bp->b_runningbufspace = 0;
911 * Only acquire the lock and wakeup on the transition from exceeding
912 * the threshold to falling below it.
914 if (space < lorunningspace)
916 if (space - bspace > lorunningspace)
922 * waitrunningbufspace()
924 * runningbufspace is a measure of the amount of I/O currently
925 * running. This routine is used in async-write situations to
926 * prevent creating huge backups of pending writes to a device.
927 * Only asynchronous writes are governed by this function.
929 * This does NOT turn an async write into a sync write. It waits
930 * for earlier writes to complete and generally returns before the
931 * caller's write has reached the device.
934 waitrunningbufspace(void)
937 mtx_lock(&rbreqlock);
938 while (runningbufspace > hirunningspace) {
940 msleep(&runningbufreq, &rbreqlock, PVM, "wdrain", 0);
942 mtx_unlock(&rbreqlock);
947 * vfs_buf_test_cache:
949 * Called when a buffer is extended. This function clears the B_CACHE
950 * bit if the newly extended portion of the buffer does not contain
954 vfs_buf_test_cache(struct buf *bp, vm_ooffset_t foff, vm_offset_t off,
955 vm_offset_t size, vm_page_t m)
959 * This function and its results are protected by higher level
960 * synchronization requiring vnode and buf locks to page in and
963 if (bp->b_flags & B_CACHE) {
964 int base = (foff + off) & PAGE_MASK;
965 if (vm_page_is_valid(m, base, size) == 0)
966 bp->b_flags &= ~B_CACHE;
970 /* Wake up the buffer daemon if necessary */
976 if (bd_request == 0) {
984 * Adjust the maxbcachbuf tunable.
987 maxbcachebuf_adjust(void)
992 * maxbcachebuf must be a power of 2 >= MAXBSIZE.
995 while (i * 2 <= maxbcachebuf)
998 if (maxbcachebuf < MAXBSIZE)
999 maxbcachebuf = MAXBSIZE;
1000 if (maxbcachebuf > MAXPHYS)
1001 maxbcachebuf = MAXPHYS;
1002 if (bootverbose != 0 && maxbcachebuf != MAXBCACHEBUF)
1003 printf("maxbcachebuf=%d\n", maxbcachebuf);
1007 * bd_speedup - speedup the buffer cache flushing code
1016 if (bd_speedupreq == 0 || bd_request == 0)
1021 wakeup(&bd_request);
1022 mtx_unlock(&bdlock);
1026 #define TRANSIENT_DENOM 5
1028 #define TRANSIENT_DENOM 10
1032 * Calculating buffer cache scaling values and reserve space for buffer
1033 * headers. This is called during low level kernel initialization and
1034 * may be called more then once. We CANNOT write to the memory area
1035 * being reserved at this time.
1038 kern_vfs_bio_buffer_alloc(caddr_t v, long physmem_est)
1041 long maxbuf, maxbuf_sz, buf_sz, biotmap_sz;
1044 * physmem_est is in pages. Convert it to kilobytes (assumes
1045 * PAGE_SIZE is >= 1K)
1047 physmem_est = physmem_est * (PAGE_SIZE / 1024);
1049 maxbcachebuf_adjust();
1051 * The nominal buffer size (and minimum KVA allocation) is BKVASIZE.
1052 * For the first 64MB of ram nominally allocate sufficient buffers to
1053 * cover 1/4 of our ram. Beyond the first 64MB allocate additional
1054 * buffers to cover 1/10 of our ram over 64MB. When auto-sizing
1055 * the buffer cache we limit the eventual kva reservation to
1058 * factor represents the 1/4 x ram conversion.
1061 int factor = 4 * BKVASIZE / 1024;
1064 if (physmem_est > 4096)
1065 nbuf += min((physmem_est - 4096) / factor,
1067 if (physmem_est > 65536)
1068 nbuf += min((physmem_est - 65536) * 2 / (factor * 5),
1069 32 * 1024 * 1024 / (factor * 5));
1071 if (maxbcache && nbuf > maxbcache / BKVASIZE)
1072 nbuf = maxbcache / BKVASIZE;
1077 /* XXX Avoid unsigned long overflows later on with maxbufspace. */
1078 maxbuf = (LONG_MAX / 3) / BKVASIZE;
1079 if (nbuf > maxbuf) {
1081 printf("Warning: nbufs lowered from %d to %ld\n", nbuf,
1087 * Ideal allocation size for the transient bio submap is 10%
1088 * of the maximal space buffer map. This roughly corresponds
1089 * to the amount of the buffer mapped for typical UFS load.
1091 * Clip the buffer map to reserve space for the transient
1092 * BIOs, if its extent is bigger than 90% (80% on i386) of the
1093 * maximum buffer map extent on the platform.
1095 * The fall-back to the maxbuf in case of maxbcache unset,
1096 * allows to not trim the buffer KVA for the architectures
1097 * with ample KVA space.
1099 if (bio_transient_maxcnt == 0 && unmapped_buf_allowed) {
1100 maxbuf_sz = maxbcache != 0 ? maxbcache : maxbuf * BKVASIZE;
1101 buf_sz = (long)nbuf * BKVASIZE;
1102 if (buf_sz < maxbuf_sz / TRANSIENT_DENOM *
1103 (TRANSIENT_DENOM - 1)) {
1105 * There is more KVA than memory. Do not
1106 * adjust buffer map size, and assign the rest
1107 * of maxbuf to transient map.
1109 biotmap_sz = maxbuf_sz - buf_sz;
1112 * Buffer map spans all KVA we could afford on
1113 * this platform. Give 10% (20% on i386) of
1114 * the buffer map to the transient bio map.
1116 biotmap_sz = buf_sz / TRANSIENT_DENOM;
1117 buf_sz -= biotmap_sz;
1119 if (biotmap_sz / INT_MAX > MAXPHYS)
1120 bio_transient_maxcnt = INT_MAX;
1122 bio_transient_maxcnt = biotmap_sz / MAXPHYS;
1124 * Artificially limit to 1024 simultaneous in-flight I/Os
1125 * using the transient mapping.
1127 if (bio_transient_maxcnt > 1024)
1128 bio_transient_maxcnt = 1024;
1130 nbuf = buf_sz / BKVASIZE;
1134 nswbuf = min(nbuf / 4, 256);
1135 if (nswbuf < NSWBUF_MIN)
1136 nswbuf = NSWBUF_MIN;
1140 * Reserve space for the buffer cache buffers
1143 v = (caddr_t)(buf + nbuf);
1148 /* Initialize the buffer subsystem. Called before use of any buffers. */
1155 KASSERT(maxbcachebuf >= MAXBSIZE,
1156 ("maxbcachebuf (%d) must be >= MAXBSIZE (%d)\n", maxbcachebuf,
1158 bq_init(&bqempty, QUEUE_EMPTY, -1, "bufq empty lock");
1159 mtx_init(&rbreqlock, "runningbufspace lock", NULL, MTX_DEF);
1160 mtx_init(&bdlock, "buffer daemon lock", NULL, MTX_DEF);
1161 mtx_init(&bdirtylock, "dirty buf lock", NULL, MTX_DEF);
1163 unmapped_buf = (caddr_t)kva_alloc(MAXPHYS);
1165 /* finally, initialize each buffer header and stick on empty q */
1166 for (i = 0; i < nbuf; i++) {
1168 bzero(bp, sizeof *bp);
1169 bp->b_flags = B_INVAL;
1170 bp->b_rcred = NOCRED;
1171 bp->b_wcred = NOCRED;
1172 bp->b_qindex = QUEUE_NONE;
1174 bp->b_subqueue = mp_maxid + 1;
1176 bp->b_data = bp->b_kvabase = unmapped_buf;
1177 LIST_INIT(&bp->b_dep);
1179 bq_insert(&bqempty, bp, false);
1183 * maxbufspace is the absolute maximum amount of buffer space we are
1184 * allowed to reserve in KVM and in real terms. The absolute maximum
1185 * is nominally used by metadata. hibufspace is the nominal maximum
1186 * used by most other requests. The differential is required to
1187 * ensure that metadata deadlocks don't occur.
1189 * maxbufspace is based on BKVASIZE. Allocating buffers larger then
1190 * this may result in KVM fragmentation which is not handled optimally
1191 * by the system. XXX This is less true with vmem. We could use
1194 maxbufspace = (long)nbuf * BKVASIZE;
1195 hibufspace = lmax(3 * maxbufspace / 4, maxbufspace - maxbcachebuf * 10);
1196 lobufspace = (hibufspace / 20) * 19; /* 95% */
1197 bufspacethresh = lobufspace + (hibufspace - lobufspace) / 2;
1200 * Note: The 16 MiB upper limit for hirunningspace was chosen
1201 * arbitrarily and may need further tuning. It corresponds to
1202 * 128 outstanding write IO requests (if IO size is 128 KiB),
1203 * which fits with many RAID controllers' tagged queuing limits.
1204 * The lower 1 MiB limit is the historical upper limit for
1207 hirunningspace = lmax(lmin(roundup(hibufspace / 64, maxbcachebuf),
1208 16 * 1024 * 1024), 1024 * 1024);
1209 lorunningspace = roundup((hirunningspace * 2) / 3, maxbcachebuf);
1212 * Limit the amount of malloc memory since it is wired permanently into
1213 * the kernel space. Even though this is accounted for in the buffer
1214 * allocation, we don't want the malloced region to grow uncontrolled.
1215 * The malloc scheme improves memory utilization significantly on
1216 * average (small) directories.
1218 maxbufmallocspace = hibufspace / 20;
1221 * Reduce the chance of a deadlock occurring by limiting the number
1222 * of delayed-write dirty buffers we allow to stack up.
1224 hidirtybuffers = nbuf / 4 + 20;
1225 dirtybufthresh = hidirtybuffers * 9 / 10;
1227 * To support extreme low-memory systems, make sure hidirtybuffers
1228 * cannot eat up all available buffer space. This occurs when our
1229 * minimum cannot be met. We try to size hidirtybuffers to 3/4 our
1230 * buffer space assuming BKVASIZE'd buffers.
1232 while ((long)hidirtybuffers * BKVASIZE > 3 * hibufspace / 4) {
1233 hidirtybuffers >>= 1;
1235 lodirtybuffers = hidirtybuffers / 2;
1238 * lofreebuffers should be sufficient to avoid stalling waiting on
1239 * buf headers under heavy utilization. The bufs in per-cpu caches
1240 * are counted as free but will be unavailable to threads executing
1243 * hifreebuffers is the free target for the bufspace daemon. This
1244 * should be set appropriately to limit work per-iteration.
1246 lofreebuffers = MIN((nbuf / 25) + (20 * mp_ncpus), 128 * mp_ncpus);
1247 hifreebuffers = (3 * lofreebuffers) / 2;
1248 numfreebuffers = nbuf;
1250 /* Setup the kva and free list allocators. */
1251 vmem_set_reclaim(buffer_arena, bufkva_reclaim);
1252 buf_zone = uma_zcache_create("buf free cache", sizeof(struct buf),
1253 NULL, NULL, NULL, NULL, buf_import, buf_release, NULL, 0);
1256 * Size the clean queue according to the amount of buffer space.
1257 * One queue per-256mb up to the max. More queues gives better
1258 * concurrency but less accurate LRU.
1260 buf_domains = MIN(howmany(maxbufspace, 256*1024*1024), BUF_DOMAINS);
1261 for (i = 0 ; i < buf_domains; i++) {
1262 struct bufdomain *bd;
1266 bd->bd_freebuffers = nbuf / buf_domains;
1267 bd->bd_hifreebuffers = hifreebuffers / buf_domains;
1268 bd->bd_lofreebuffers = lofreebuffers / buf_domains;
1269 bd->bd_bufspace = 0;
1270 bd->bd_maxbufspace = maxbufspace / buf_domains;
1271 bd->bd_hibufspace = hibufspace / buf_domains;
1272 bd->bd_lobufspace = lobufspace / buf_domains;
1273 bd->bd_bufspacethresh = bufspacethresh / buf_domains;
1274 bd->bd_numdirtybuffers = 0;
1275 bd->bd_hidirtybuffers = hidirtybuffers / buf_domains;
1276 bd->bd_lodirtybuffers = lodirtybuffers / buf_domains;
1277 bd->bd_dirtybufthresh = dirtybufthresh / buf_domains;
1278 /* Don't allow more than 2% of bufs in the per-cpu caches. */
1279 bd->bd_lim = nbuf / buf_domains / 50 / mp_ncpus;
1281 getnewbufcalls = counter_u64_alloc(M_WAITOK);
1282 getnewbufrestarts = counter_u64_alloc(M_WAITOK);
1283 mappingrestarts = counter_u64_alloc(M_WAITOK);
1284 numbufallocfails = counter_u64_alloc(M_WAITOK);
1285 notbufdflushes = counter_u64_alloc(M_WAITOK);
1286 buffreekvacnt = counter_u64_alloc(M_WAITOK);
1287 bufdefragcnt = counter_u64_alloc(M_WAITOK);
1288 bufkvaspace = counter_u64_alloc(M_WAITOK);
1293 vfs_buf_check_mapped(struct buf *bp)
1296 KASSERT(bp->b_kvabase != unmapped_buf,
1297 ("mapped buf: b_kvabase was not updated %p", bp));
1298 KASSERT(bp->b_data != unmapped_buf,
1299 ("mapped buf: b_data was not updated %p", bp));
1300 KASSERT(bp->b_data < unmapped_buf || bp->b_data >= unmapped_buf +
1301 MAXPHYS, ("b_data + b_offset unmapped %p", bp));
1305 vfs_buf_check_unmapped(struct buf *bp)
1308 KASSERT(bp->b_data == unmapped_buf,
1309 ("unmapped buf: corrupted b_data %p", bp));
1312 #define BUF_CHECK_MAPPED(bp) vfs_buf_check_mapped(bp)
1313 #define BUF_CHECK_UNMAPPED(bp) vfs_buf_check_unmapped(bp)
1315 #define BUF_CHECK_MAPPED(bp) do {} while (0)
1316 #define BUF_CHECK_UNMAPPED(bp) do {} while (0)
1320 isbufbusy(struct buf *bp)
1322 if (((bp->b_flags & B_INVAL) == 0 && BUF_ISLOCKED(bp)) ||
1323 ((bp->b_flags & (B_DELWRI | B_INVAL)) == B_DELWRI))
1329 * Shutdown the system cleanly to prepare for reboot, halt, or power off.
1332 bufshutdown(int show_busybufs)
1334 static int first_buf_printf = 1;
1336 int iter, nbusy, pbusy;
1342 * Sync filesystems for shutdown
1344 wdog_kern_pat(WD_LASTVAL);
1345 kern_sync(curthread);
1348 * With soft updates, some buffers that are
1349 * written will be remarked as dirty until other
1350 * buffers are written.
1352 for (iter = pbusy = 0; iter < 20; iter++) {
1354 for (bp = &buf[nbuf]; --bp >= buf; )
1358 if (first_buf_printf)
1359 printf("All buffers synced.");
1362 if (first_buf_printf) {
1363 printf("Syncing disks, buffers remaining... ");
1364 first_buf_printf = 0;
1366 printf("%d ", nbusy);
1371 wdog_kern_pat(WD_LASTVAL);
1372 kern_sync(curthread);
1376 * Spin for a while to allow interrupt threads to run.
1378 DELAY(50000 * iter);
1381 * Context switch several times to allow interrupt
1384 for (subiter = 0; subiter < 50 * iter; subiter++) {
1385 thread_lock(curthread);
1393 * Count only busy local buffers to prevent forcing
1394 * a fsck if we're just a client of a wedged NFS server
1397 for (bp = &buf[nbuf]; --bp >= buf; ) {
1398 if (isbufbusy(bp)) {
1400 /* XXX: This is bogus. We should probably have a BO_REMOTE flag instead */
1401 if (bp->b_dev == NULL) {
1402 TAILQ_REMOVE(&mountlist,
1403 bp->b_vp->v_mount, mnt_list);
1408 if (show_busybufs > 0) {
1410 "%d: buf:%p, vnode:%p, flags:%0x, blkno:%jd, lblkno:%jd, buflock:",
1411 nbusy, bp, bp->b_vp, bp->b_flags,
1412 (intmax_t)bp->b_blkno,
1413 (intmax_t)bp->b_lblkno);
1414 BUF_LOCKPRINTINFO(bp);
1415 if (show_busybufs > 1)
1423 * Failed to sync all blocks. Indicate this and don't
1424 * unmount filesystems (thus forcing an fsck on reboot).
1426 printf("Giving up on %d buffers\n", nbusy);
1427 DELAY(5000000); /* 5 seconds */
1429 if (!first_buf_printf)
1430 printf("Final sync complete\n");
1432 * Unmount filesystems
1434 if (panicstr == NULL)
1438 DELAY(100000); /* wait for console output to finish */
1442 bpmap_qenter(struct buf *bp)
1445 BUF_CHECK_MAPPED(bp);
1448 * bp->b_data is relative to bp->b_offset, but
1449 * bp->b_offset may be offset into the first page.
1451 bp->b_data = (caddr_t)trunc_page((vm_offset_t)bp->b_data);
1452 pmap_qenter((vm_offset_t)bp->b_data, bp->b_pages, bp->b_npages);
1453 bp->b_data = (caddr_t)((vm_offset_t)bp->b_data |
1454 (vm_offset_t)(bp->b_offset & PAGE_MASK));
1457 static inline struct bufdomain *
1458 bufdomain(struct buf *bp)
1461 return (&bdomain[bp->b_domain]);
1464 static struct bufqueue *
1465 bufqueue(struct buf *bp)
1468 switch (bp->b_qindex) {
1471 case QUEUE_SENTINEL:
1476 return (&bufdomain(bp)->bd_dirtyq);
1478 return (&bufdomain(bp)->bd_subq[bp->b_subqueue]);
1482 panic("bufqueue(%p): Unhandled type %d\n", bp, bp->b_qindex);
1486 * Return the locked bufqueue that bp is a member of.
1488 static struct bufqueue *
1489 bufqueue_acquire(struct buf *bp)
1491 struct bufqueue *bq, *nbq;
1494 * bp can be pushed from a per-cpu queue to the
1495 * cleanq while we're waiting on the lock. Retry
1496 * if the queues don't match.
1514 * Insert the buffer into the appropriate free list. Requires a
1515 * locked buffer on entry and buffer is unlocked before return.
1518 binsfree(struct buf *bp, int qindex)
1520 struct bufdomain *bd;
1521 struct bufqueue *bq;
1523 KASSERT(qindex == QUEUE_CLEAN || qindex == QUEUE_DIRTY,
1524 ("binsfree: Invalid qindex %d", qindex));
1525 BUF_ASSERT_XLOCKED(bp);
1528 * Handle delayed bremfree() processing.
1530 if (bp->b_flags & B_REMFREE) {
1531 if (bp->b_qindex == qindex) {
1532 bp->b_flags |= B_REUSE;
1533 bp->b_flags &= ~B_REMFREE;
1537 bq = bufqueue_acquire(bp);
1542 if (qindex == QUEUE_CLEAN) {
1543 if (bd->bd_lim != 0)
1544 bq = &bd->bd_subq[PCPU_GET(cpuid)];
1548 bq = &bd->bd_dirtyq;
1549 bq_insert(bq, bp, true);
1555 * Free a buffer to the buf zone once it no longer has valid contents.
1558 buf_free(struct buf *bp)
1561 if (bp->b_flags & B_REMFREE)
1563 if (bp->b_vflags & BV_BKGRDINPROG)
1564 panic("losing buffer 1");
1565 if (bp->b_rcred != NOCRED) {
1566 crfree(bp->b_rcred);
1567 bp->b_rcred = NOCRED;
1569 if (bp->b_wcred != NOCRED) {
1570 crfree(bp->b_wcred);
1571 bp->b_wcred = NOCRED;
1573 if (!LIST_EMPTY(&bp->b_dep))
1576 atomic_add_int(&bufdomain(bp)->bd_freebuffers, 1);
1578 uma_zfree(buf_zone, bp);
1584 * Import bufs into the uma cache from the buf list. The system still
1585 * expects a static array of bufs and much of the synchronization
1586 * around bufs assumes type stable storage. As a result, UMA is used
1587 * only as a per-cpu cache of bufs still maintained on a global list.
1590 buf_import(void *arg, void **store, int cnt, int domain, int flags)
1596 for (i = 0; i < cnt; i++) {
1597 bp = TAILQ_FIRST(&bqempty.bq_queue);
1600 bq_remove(&bqempty, bp);
1603 BQ_UNLOCK(&bqempty);
1611 * Release bufs from the uma cache back to the buffer queues.
1614 buf_release(void *arg, void **store, int cnt)
1616 struct bufqueue *bq;
1622 for (i = 0; i < cnt; i++) {
1624 /* Inline bq_insert() to batch locking. */
1625 TAILQ_INSERT_TAIL(&bq->bq_queue, bp, b_freelist);
1626 bp->b_flags &= ~(B_AGE | B_REUSE);
1628 bp->b_qindex = bq->bq_index;
1636 * Allocate an empty buffer header.
1639 buf_alloc(struct bufdomain *bd)
1645 * We can only run out of bufs in the buf zone if the average buf
1646 * is less than BKVASIZE. In this case the actual wait/block will
1647 * come from buf_reycle() failing to flush one of these small bufs.
1650 freebufs = atomic_fetchadd_int(&bd->bd_freebuffers, -1);
1652 bp = uma_zalloc(buf_zone, M_NOWAIT);
1654 atomic_add_int(&bd->bd_freebuffers, 1);
1655 bufspace_daemon_wakeup(bd);
1656 counter_u64_add(numbufallocfails, 1);
1660 * Wake-up the bufspace daemon on transition below threshold.
1662 if (freebufs == bd->bd_lofreebuffers)
1663 bufspace_daemon_wakeup(bd);
1665 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0)
1666 panic("getnewbuf_empty: Locked buf %p on free queue.", bp);
1668 KASSERT(bp->b_vp == NULL,
1669 ("bp: %p still has vnode %p.", bp, bp->b_vp));
1670 KASSERT((bp->b_flags & (B_DELWRI | B_NOREUSE)) == 0,
1671 ("invalid buffer %p flags %#x", bp, bp->b_flags));
1672 KASSERT((bp->b_xflags & (BX_VNCLEAN|BX_VNDIRTY)) == 0,
1673 ("bp: %p still on a buffer list. xflags %X", bp, bp->b_xflags));
1674 KASSERT(bp->b_npages == 0,
1675 ("bp: %p still has %d vm pages\n", bp, bp->b_npages));
1676 KASSERT(bp->b_kvasize == 0, ("bp: %p still has kva\n", bp));
1677 KASSERT(bp->b_bufsize == 0, ("bp: %p still has bufspace\n", bp));
1679 bp->b_domain = BD_DOMAIN(bd);
1685 bp->b_blkno = bp->b_lblkno = 0;
1686 bp->b_offset = NOOFFSET;
1692 bp->b_dirtyoff = bp->b_dirtyend = 0;
1693 bp->b_bufobj = NULL;
1694 bp->b_data = bp->b_kvabase = unmapped_buf;
1695 bp->b_fsprivate1 = NULL;
1696 bp->b_fsprivate2 = NULL;
1697 bp->b_fsprivate3 = NULL;
1698 LIST_INIT(&bp->b_dep);
1706 * Free a buffer from the given bufqueue. kva controls whether the
1707 * freed buf must own some kva resources. This is used for
1711 buf_recycle(struct bufdomain *bd, bool kva)
1713 struct bufqueue *bq;
1714 struct buf *bp, *nbp;
1717 counter_u64_add(bufdefragcnt, 1);
1721 KASSERT(BQ_LOCKPTR(bq) == BD_LOCKPTR(bd),
1722 ("buf_recycle: Locks don't match"));
1723 nbp = TAILQ_FIRST(&bq->bq_queue);
1726 * Run scan, possibly freeing data and/or kva mappings on the fly
1729 while ((bp = nbp) != NULL) {
1731 * Calculate next bp (we can only use it if we do not
1732 * release the bqlock).
1734 nbp = TAILQ_NEXT(bp, b_freelist);
1737 * If we are defragging then we need a buffer with
1738 * some kva to reclaim.
1740 if (kva && bp->b_kvasize == 0)
1743 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0)
1747 * Implement a second chance algorithm for frequently
1750 if ((bp->b_flags & B_REUSE) != 0) {
1751 TAILQ_REMOVE(&bq->bq_queue, bp, b_freelist);
1752 TAILQ_INSERT_TAIL(&bq->bq_queue, bp, b_freelist);
1753 bp->b_flags &= ~B_REUSE;
1759 * Skip buffers with background writes in progress.
1761 if ((bp->b_vflags & BV_BKGRDINPROG) != 0) {
1766 KASSERT(bp->b_qindex == QUEUE_CLEAN,
1767 ("buf_recycle: inconsistent queue %d bp %p",
1769 KASSERT(bp->b_domain == BD_DOMAIN(bd),
1770 ("getnewbuf: queue domain %d doesn't match request %d",
1771 bp->b_domain, (int)BD_DOMAIN(bd)));
1773 * NOTE: nbp is now entirely invalid. We can only restart
1774 * the scan from this point on.
1780 * Requeue the background write buffer with error and
1783 if ((bp->b_vflags & BV_BKGRDERR) != 0) {
1786 nbp = TAILQ_FIRST(&bq->bq_queue);
1789 bp->b_flags |= B_INVAL;
1802 * Mark the buffer for removal from the appropriate free list.
1806 bremfree(struct buf *bp)
1809 CTR3(KTR_BUF, "bremfree(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
1810 KASSERT((bp->b_flags & B_REMFREE) == 0,
1811 ("bremfree: buffer %p already marked for delayed removal.", bp));
1812 KASSERT(bp->b_qindex != QUEUE_NONE,
1813 ("bremfree: buffer %p not on a queue.", bp));
1814 BUF_ASSERT_XLOCKED(bp);
1816 bp->b_flags |= B_REMFREE;
1822 * Force an immediate removal from a free list. Used only in nfs when
1823 * it abuses the b_freelist pointer.
1826 bremfreef(struct buf *bp)
1828 struct bufqueue *bq;
1830 bq = bufqueue_acquire(bp);
1836 bq_init(struct bufqueue *bq, int qindex, int subqueue, const char *lockname)
1839 mtx_init(&bq->bq_lock, lockname, NULL, MTX_DEF);
1840 TAILQ_INIT(&bq->bq_queue);
1842 bq->bq_index = qindex;
1843 bq->bq_subqueue = subqueue;
1847 bd_init(struct bufdomain *bd)
1851 bd->bd_cleanq = &bd->bd_subq[mp_maxid + 1];
1852 bq_init(bd->bd_cleanq, QUEUE_CLEAN, mp_maxid + 1, "bufq clean lock");
1853 bq_init(&bd->bd_dirtyq, QUEUE_DIRTY, -1, "bufq dirty lock");
1854 for (i = 0; i <= mp_maxid; i++)
1855 bq_init(&bd->bd_subq[i], QUEUE_CLEAN, i,
1856 "bufq clean subqueue lock");
1857 mtx_init(&bd->bd_run_lock, "bufspace daemon run lock", NULL, MTX_DEF);
1863 * Removes a buffer from the free list, must be called with the
1864 * correct qlock held.
1867 bq_remove(struct bufqueue *bq, struct buf *bp)
1870 CTR3(KTR_BUF, "bq_remove(%p) vp %p flags %X",
1871 bp, bp->b_vp, bp->b_flags);
1872 KASSERT(bp->b_qindex != QUEUE_NONE,
1873 ("bq_remove: buffer %p not on a queue.", bp));
1874 KASSERT(bufqueue(bp) == bq,
1875 ("bq_remove: Remove buffer %p from wrong queue.", bp));
1877 BQ_ASSERT_LOCKED(bq);
1878 if (bp->b_qindex != QUEUE_EMPTY) {
1879 BUF_ASSERT_XLOCKED(bp);
1881 KASSERT(bq->bq_len >= 1,
1882 ("queue %d underflow", bp->b_qindex));
1883 TAILQ_REMOVE(&bq->bq_queue, bp, b_freelist);
1885 bp->b_qindex = QUEUE_NONE;
1886 bp->b_flags &= ~(B_REMFREE | B_REUSE);
1890 bd_flush(struct bufdomain *bd, struct bufqueue *bq)
1894 BQ_ASSERT_LOCKED(bq);
1895 if (bq != bd->bd_cleanq) {
1897 while ((bp = TAILQ_FIRST(&bq->bq_queue)) != NULL) {
1898 TAILQ_REMOVE(&bq->bq_queue, bp, b_freelist);
1899 TAILQ_INSERT_TAIL(&bd->bd_cleanq->bq_queue, bp,
1901 bp->b_subqueue = bd->bd_cleanq->bq_subqueue;
1903 bd->bd_cleanq->bq_len += bq->bq_len;
1906 if (bd->bd_wanted) {
1908 wakeup(&bd->bd_wanted);
1910 if (bq != bd->bd_cleanq)
1915 bd_flushall(struct bufdomain *bd)
1917 struct bufqueue *bq;
1921 if (bd->bd_lim == 0)
1924 for (i = 0; i <= mp_maxid; i++) {
1925 bq = &bd->bd_subq[i];
1926 if (bq->bq_len == 0)
1938 bq_insert(struct bufqueue *bq, struct buf *bp, bool unlock)
1940 struct bufdomain *bd;
1942 if (bp->b_qindex != QUEUE_NONE)
1943 panic("bq_insert: free buffer %p onto another queue?", bp);
1946 if (bp->b_flags & B_AGE) {
1947 /* Place this buf directly on the real queue. */
1948 if (bq->bq_index == QUEUE_CLEAN)
1951 TAILQ_INSERT_HEAD(&bq->bq_queue, bp, b_freelist);
1954 TAILQ_INSERT_TAIL(&bq->bq_queue, bp, b_freelist);
1956 bp->b_flags &= ~(B_AGE | B_REUSE);
1958 bp->b_qindex = bq->bq_index;
1959 bp->b_subqueue = bq->bq_subqueue;
1962 * Unlock before we notify so that we don't wakeup a waiter that
1963 * fails a trylock on the buf and sleeps again.
1968 if (bp->b_qindex == QUEUE_CLEAN) {
1970 * Flush the per-cpu queue and notify any waiters.
1972 if (bd->bd_wanted || (bq != bd->bd_cleanq &&
1973 bq->bq_len >= bd->bd_lim))
1982 * Free the kva allocation for a buffer.
1986 bufkva_free(struct buf *bp)
1990 if (bp->b_kvasize == 0) {
1991 KASSERT(bp->b_kvabase == unmapped_buf &&
1992 bp->b_data == unmapped_buf,
1993 ("Leaked KVA space on %p", bp));
1994 } else if (buf_mapped(bp))
1995 BUF_CHECK_MAPPED(bp);
1997 BUF_CHECK_UNMAPPED(bp);
1999 if (bp->b_kvasize == 0)
2002 vmem_free(buffer_arena, (vm_offset_t)bp->b_kvabase, bp->b_kvasize);
2003 counter_u64_add(bufkvaspace, -bp->b_kvasize);
2004 counter_u64_add(buffreekvacnt, 1);
2005 bp->b_data = bp->b_kvabase = unmapped_buf;
2012 * Allocate the buffer KVA and set b_kvasize and b_kvabase.
2015 bufkva_alloc(struct buf *bp, int maxsize, int gbflags)
2020 KASSERT((gbflags & GB_UNMAPPED) == 0 || (gbflags & GB_KVAALLOC) != 0,
2021 ("Invalid gbflags 0x%x in %s", gbflags, __func__));
2026 error = vmem_alloc(buffer_arena, maxsize, M_BESTFIT | M_NOWAIT, &addr);
2029 * Buffer map is too fragmented. Request the caller
2030 * to defragment the map.
2034 bp->b_kvabase = (caddr_t)addr;
2035 bp->b_kvasize = maxsize;
2036 counter_u64_add(bufkvaspace, bp->b_kvasize);
2037 if ((gbflags & GB_UNMAPPED) != 0) {
2038 bp->b_data = unmapped_buf;
2039 BUF_CHECK_UNMAPPED(bp);
2041 bp->b_data = bp->b_kvabase;
2042 BUF_CHECK_MAPPED(bp);
2050 * Reclaim buffer kva by freeing buffers holding kva. This is a vmem
2051 * callback that fires to avoid returning failure.
2054 bufkva_reclaim(vmem_t *vmem, int flags)
2061 for (i = 0; i < 5; i++) {
2062 for (q = 0; q < buf_domains; q++)
2063 if (buf_recycle(&bdomain[q], true) != 0)
2072 * Attempt to initiate asynchronous I/O on read-ahead blocks. We must
2073 * clear BIO_ERROR and B_INVAL prior to initiating I/O . If B_CACHE is set,
2074 * the buffer is valid and we do not have to do anything.
2077 breada(struct vnode * vp, daddr_t * rablkno, int * rabsize, int cnt,
2078 struct ucred * cred, int flags, void (*ckhashfunc)(struct buf *))
2086 for (i = 0; i < cnt; i++, rablkno++, rabsize++) {
2087 if (inmem(vp, *rablkno))
2089 rabp = getblk(vp, *rablkno, *rabsize, 0, 0, 0);
2090 if ((rabp->b_flags & B_CACHE) != 0) {
2097 racct_add_buf(curproc, rabp, 0);
2098 PROC_UNLOCK(curproc);
2101 td->td_ru.ru_inblock++;
2102 rabp->b_flags |= B_ASYNC;
2103 rabp->b_flags &= ~B_INVAL;
2104 if ((flags & GB_CKHASH) != 0) {
2105 rabp->b_flags |= B_CKHASH;
2106 rabp->b_ckhashcalc = ckhashfunc;
2108 rabp->b_ioflags &= ~BIO_ERROR;
2109 rabp->b_iocmd = BIO_READ;
2110 if (rabp->b_rcred == NOCRED && cred != NOCRED)
2111 rabp->b_rcred = crhold(cred);
2112 vfs_busy_pages(rabp, 0);
2114 rabp->b_iooffset = dbtob(rabp->b_blkno);
2120 * Entry point for bread() and breadn() via #defines in sys/buf.h.
2122 * Get a buffer with the specified data. Look in the cache first. We
2123 * must clear BIO_ERROR and B_INVAL prior to initiating I/O. If B_CACHE
2124 * is set, the buffer is valid and we do not have to do anything, see
2125 * getblk(). Also starts asynchronous I/O on read-ahead blocks.
2127 * Always return a NULL buffer pointer (in bpp) when returning an error.
2129 * The blkno parameter is the logical block being requested. Normally
2130 * the mapping of logical block number to disk block address is done
2131 * by calling VOP_BMAP(). However, if the mapping is already known, the
2132 * disk block address can be passed using the dblkno parameter. If the
2133 * disk block address is not known, then the same value should be passed
2134 * for blkno and dblkno.
2137 breadn_flags(struct vnode *vp, daddr_t blkno, daddr_t dblkno, int size,
2138 daddr_t *rablkno, int *rabsize, int cnt, struct ucred *cred, int flags,
2139 void (*ckhashfunc)(struct buf *), struct buf **bpp)
2143 int error, readwait, rv;
2145 CTR3(KTR_BUF, "breadn(%p, %jd, %d)", vp, blkno, size);
2148 * Can only return NULL if GB_LOCK_NOWAIT or GB_SPARSE flags
2151 error = getblkx(vp, blkno, dblkno, size, 0, 0, flags, &bp);
2156 KASSERT(blkno == bp->b_lblkno,
2157 ("getblkx returned buffer for blkno %jd instead of blkno %jd",
2158 (intmax_t)bp->b_lblkno, (intmax_t)blkno));
2159 flags &= ~GB_NOSPARSE;
2163 * If not found in cache, do some I/O
2166 if ((bp->b_flags & B_CACHE) == 0) {
2169 PROC_LOCK(td->td_proc);
2170 racct_add_buf(td->td_proc, bp, 0);
2171 PROC_UNLOCK(td->td_proc);
2174 td->td_ru.ru_inblock++;
2175 bp->b_iocmd = BIO_READ;
2176 bp->b_flags &= ~B_INVAL;
2177 if ((flags & GB_CKHASH) != 0) {
2178 bp->b_flags |= B_CKHASH;
2179 bp->b_ckhashcalc = ckhashfunc;
2181 bp->b_ioflags &= ~BIO_ERROR;
2182 if (bp->b_rcred == NOCRED && cred != NOCRED)
2183 bp->b_rcred = crhold(cred);
2184 vfs_busy_pages(bp, 0);
2185 bp->b_iooffset = dbtob(bp->b_blkno);
2191 * Attempt to initiate asynchronous I/O on read-ahead blocks.
2193 breada(vp, rablkno, rabsize, cnt, cred, flags, ckhashfunc);
2207 * Write, release buffer on completion. (Done by iodone
2208 * if async). Do not bother writing anything if the buffer
2211 * Note that we set B_CACHE here, indicating that buffer is
2212 * fully valid and thus cacheable. This is true even of NFS
2213 * now so we set it generally. This could be set either here
2214 * or in biodone() since the I/O is synchronous. We put it
2218 bufwrite(struct buf *bp)
2225 CTR3(KTR_BUF, "bufwrite(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
2226 if ((bp->b_bufobj->bo_flag & BO_DEAD) != 0) {
2227 bp->b_flags |= B_INVAL | B_RELBUF;
2228 bp->b_flags &= ~B_CACHE;
2232 if (bp->b_flags & B_INVAL) {
2237 if (bp->b_flags & B_BARRIER)
2238 atomic_add_long(&barrierwrites, 1);
2240 oldflags = bp->b_flags;
2242 KASSERT(!(bp->b_vflags & BV_BKGRDINPROG),
2243 ("FFS background buffer should not get here %p", bp));
2247 vp_md = vp->v_vflag & VV_MD;
2252 * Mark the buffer clean. Increment the bufobj write count
2253 * before bundirty() call, to prevent other thread from seeing
2254 * empty dirty list and zero counter for writes in progress,
2255 * falsely indicating that the bufobj is clean.
2257 bufobj_wref(bp->b_bufobj);
2260 bp->b_flags &= ~B_DONE;
2261 bp->b_ioflags &= ~BIO_ERROR;
2262 bp->b_flags |= B_CACHE;
2263 bp->b_iocmd = BIO_WRITE;
2265 vfs_busy_pages(bp, 1);
2268 * Normal bwrites pipeline writes
2270 bp->b_runningbufspace = bp->b_bufsize;
2271 space = atomic_fetchadd_long(&runningbufspace, bp->b_runningbufspace);
2276 racct_add_buf(curproc, bp, 1);
2277 PROC_UNLOCK(curproc);
2280 curthread->td_ru.ru_oublock++;
2281 if (oldflags & B_ASYNC)
2283 bp->b_iooffset = dbtob(bp->b_blkno);
2284 buf_track(bp, __func__);
2287 if ((oldflags & B_ASYNC) == 0) {
2288 int rtval = bufwait(bp);
2291 } else if (space > hirunningspace) {
2293 * don't allow the async write to saturate the I/O
2294 * system. We will not deadlock here because
2295 * we are blocking waiting for I/O that is already in-progress
2296 * to complete. We do not block here if it is the update
2297 * or syncer daemon trying to clean up as that can lead
2300 if ((curthread->td_pflags & TDP_NORUNNINGBUF) == 0 && !vp_md)
2301 waitrunningbufspace();
2308 bufbdflush(struct bufobj *bo, struct buf *bp)
2312 if (bo->bo_dirty.bv_cnt > dirtybufthresh + 10) {
2313 (void) VOP_FSYNC(bp->b_vp, MNT_NOWAIT, curthread);
2315 } else if (bo->bo_dirty.bv_cnt > dirtybufthresh) {
2318 * Try to find a buffer to flush.
2320 TAILQ_FOREACH(nbp, &bo->bo_dirty.bv_hd, b_bobufs) {
2321 if ((nbp->b_vflags & BV_BKGRDINPROG) ||
2323 LK_EXCLUSIVE | LK_NOWAIT, NULL))
2326 panic("bdwrite: found ourselves");
2328 /* Don't countdeps with the bo lock held. */
2329 if (buf_countdeps(nbp, 0)) {
2334 if (nbp->b_flags & B_CLUSTEROK) {
2335 vfs_bio_awrite(nbp);
2340 dirtybufferflushes++;
2349 * Delayed write. (Buffer is marked dirty). Do not bother writing
2350 * anything if the buffer is marked invalid.
2352 * Note that since the buffer must be completely valid, we can safely
2353 * set B_CACHE. In fact, we have to set B_CACHE here rather then in
2354 * biodone() in order to prevent getblk from writing the buffer
2355 * out synchronously.
2358 bdwrite(struct buf *bp)
2360 struct thread *td = curthread;
2364 CTR3(KTR_BUF, "bdwrite(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
2365 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp));
2366 KASSERT((bp->b_flags & B_BARRIER) == 0,
2367 ("Barrier request in delayed write %p", bp));
2369 if (bp->b_flags & B_INVAL) {
2375 * If we have too many dirty buffers, don't create any more.
2376 * If we are wildly over our limit, then force a complete
2377 * cleanup. Otherwise, just keep the situation from getting
2378 * out of control. Note that we have to avoid a recursive
2379 * disaster and not try to clean up after our own cleanup!
2383 if ((td->td_pflags & (TDP_COWINPROGRESS|TDP_INBDFLUSH)) == 0) {
2384 td->td_pflags |= TDP_INBDFLUSH;
2386 td->td_pflags &= ~TDP_INBDFLUSH;
2392 * Set B_CACHE, indicating that the buffer is fully valid. This is
2393 * true even of NFS now.
2395 bp->b_flags |= B_CACHE;
2398 * This bmap keeps the system from needing to do the bmap later,
2399 * perhaps when the system is attempting to do a sync. Since it
2400 * is likely that the indirect block -- or whatever other datastructure
2401 * that the filesystem needs is still in memory now, it is a good
2402 * thing to do this. Note also, that if the pageout daemon is
2403 * requesting a sync -- there might not be enough memory to do
2404 * the bmap then... So, this is important to do.
2406 if (vp->v_type != VCHR && bp->b_lblkno == bp->b_blkno) {
2407 VOP_BMAP(vp, bp->b_lblkno, NULL, &bp->b_blkno, NULL, NULL);
2410 buf_track(bp, __func__);
2413 * Set the *dirty* buffer range based upon the VM system dirty
2416 * Mark the buffer pages as clean. We need to do this here to
2417 * satisfy the vnode_pager and the pageout daemon, so that it
2418 * thinks that the pages have been "cleaned". Note that since
2419 * the pages are in a delayed write buffer -- the VFS layer
2420 * "will" see that the pages get written out on the next sync,
2421 * or perhaps the cluster will be completed.
2423 vfs_clean_pages_dirty_buf(bp);
2427 * note: we cannot initiate I/O from a bdwrite even if we wanted to,
2428 * due to the softdep code.
2435 * Turn buffer into delayed write request. We must clear BIO_READ and
2436 * B_RELBUF, and we must set B_DELWRI. We reassign the buffer to
2437 * itself to properly update it in the dirty/clean lists. We mark it
2438 * B_DONE to ensure that any asynchronization of the buffer properly
2439 * clears B_DONE ( else a panic will occur later ).
2441 * bdirty() is kinda like bdwrite() - we have to clear B_INVAL which
2442 * might have been set pre-getblk(). Unlike bwrite/bdwrite, bdirty()
2443 * should only be called if the buffer is known-good.
2445 * Since the buffer is not on a queue, we do not update the numfreebuffers
2448 * The buffer must be on QUEUE_NONE.
2451 bdirty(struct buf *bp)
2454 CTR3(KTR_BUF, "bdirty(%p) vp %p flags %X",
2455 bp, bp->b_vp, bp->b_flags);
2456 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp));
2457 KASSERT(bp->b_flags & B_REMFREE || bp->b_qindex == QUEUE_NONE,
2458 ("bdirty: buffer %p still on queue %d", bp, bp->b_qindex));
2459 bp->b_flags &= ~(B_RELBUF);
2460 bp->b_iocmd = BIO_WRITE;
2462 if ((bp->b_flags & B_DELWRI) == 0) {
2463 bp->b_flags |= /* XXX B_DONE | */ B_DELWRI;
2472 * Clear B_DELWRI for buffer.
2474 * Since the buffer is not on a queue, we do not update the numfreebuffers
2477 * The buffer must be on QUEUE_NONE.
2481 bundirty(struct buf *bp)
2484 CTR3(KTR_BUF, "bundirty(%p) vp %p flags %X", 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 ("bundirty: buffer %p still on queue %d", bp, bp->b_qindex));
2489 if (bp->b_flags & B_DELWRI) {
2490 bp->b_flags &= ~B_DELWRI;
2495 * Since it is now being written, we can clear its deferred write flag.
2497 bp->b_flags &= ~B_DEFERRED;
2503 * Asynchronous write. Start output on a buffer, but do not wait for
2504 * it to complete. The buffer is released when the output completes.
2506 * bwrite() ( or the VOP routine anyway ) is responsible for handling
2507 * B_INVAL buffers. Not us.
2510 bawrite(struct buf *bp)
2513 bp->b_flags |= B_ASYNC;
2520 * Asynchronous barrier write. Start output on a buffer, but do not
2521 * wait for it to complete. Place a write barrier after this write so
2522 * that this buffer and all buffers written before it are committed to
2523 * the disk before any buffers written after this write are committed
2524 * to the disk. The buffer is released when the output completes.
2527 babarrierwrite(struct buf *bp)
2530 bp->b_flags |= B_ASYNC | B_BARRIER;
2537 * Synchronous barrier write. Start output on a buffer and wait for
2538 * it to complete. Place a write barrier after this write so that
2539 * this buffer and all buffers written before it are committed to
2540 * the disk before any buffers written after this write are committed
2541 * to the disk. The buffer is released when the output completes.
2544 bbarrierwrite(struct buf *bp)
2547 bp->b_flags |= B_BARRIER;
2548 return (bwrite(bp));
2554 * Called prior to the locking of any vnodes when we are expecting to
2555 * write. We do not want to starve the buffer cache with too many
2556 * dirty buffers so we block here. By blocking prior to the locking
2557 * of any vnodes we attempt to avoid the situation where a locked vnode
2558 * prevents the various system daemons from flushing related buffers.
2564 if (buf_dirty_count_severe()) {
2565 mtx_lock(&bdirtylock);
2566 while (buf_dirty_count_severe()) {
2568 msleep(&bdirtywait, &bdirtylock, (PRIBIO + 4),
2571 mtx_unlock(&bdirtylock);
2576 * Return true if we have too many dirty buffers.
2579 buf_dirty_count_severe(void)
2582 return (!BIT_EMPTY(BUF_DOMAINS, &bdhidirty));
2588 * Release a busy buffer and, if requested, free its resources. The
2589 * buffer will be stashed in the appropriate bufqueue[] allowing it
2590 * to be accessed later as a cache entity or reused for other purposes.
2593 brelse(struct buf *bp)
2595 struct mount *v_mnt;
2599 * Many functions erroneously call brelse with a NULL bp under rare
2600 * error conditions. Simply return when called with a NULL bp.
2604 CTR3(KTR_BUF, "brelse(%p) vp %p flags %X",
2605 bp, bp->b_vp, bp->b_flags);
2606 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)),
2607 ("brelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp));
2608 KASSERT((bp->b_flags & B_VMIO) != 0 || (bp->b_flags & B_NOREUSE) == 0,
2609 ("brelse: non-VMIO buffer marked NOREUSE"));
2611 if (BUF_LOCKRECURSED(bp)) {
2613 * Do not process, in particular, do not handle the
2614 * B_INVAL/B_RELBUF and do not release to free list.
2620 if (bp->b_flags & B_MANAGED) {
2625 if ((bp->b_vflags & (BV_BKGRDINPROG | BV_BKGRDERR)) == BV_BKGRDERR) {
2626 BO_LOCK(bp->b_bufobj);
2627 bp->b_vflags &= ~BV_BKGRDERR;
2628 BO_UNLOCK(bp->b_bufobj);
2632 if (bp->b_iocmd == BIO_WRITE && (bp->b_ioflags & BIO_ERROR) &&
2633 (bp->b_flags & B_INVALONERR)) {
2635 * Forced invalidation of dirty buffer contents, to be used
2636 * after a failed write in the rare case that the loss of the
2637 * contents is acceptable. The buffer is invalidated and
2640 bp->b_flags |= B_INVAL | B_RELBUF | B_NOCACHE;
2641 bp->b_flags &= ~(B_ASYNC | B_CACHE);
2644 if (bp->b_iocmd == BIO_WRITE && (bp->b_ioflags & BIO_ERROR) &&
2645 (bp->b_error != ENXIO || !LIST_EMPTY(&bp->b_dep)) &&
2646 !(bp->b_flags & B_INVAL)) {
2648 * Failed write, redirty. All errors except ENXIO (which
2649 * means the device is gone) are treated as being
2652 * XXX Treating EIO as transient is not correct; the
2653 * contract with the local storage device drivers is that
2654 * they will only return EIO once the I/O is no longer
2655 * retriable. Network I/O also respects this through the
2656 * guarantees of TCP and/or the internal retries of NFS.
2657 * ENOMEM might be transient, but we also have no way of
2658 * knowing when its ok to retry/reschedule. In general,
2659 * this entire case should be made obsolete through better
2660 * error handling/recovery and resource scheduling.
2662 * Do this also for buffers that failed with ENXIO, but have
2663 * non-empty dependencies - the soft updates code might need
2664 * to access the buffer to untangle them.
2666 * Must clear BIO_ERROR to prevent pages from being scrapped.
2668 bp->b_ioflags &= ~BIO_ERROR;
2670 } else if ((bp->b_flags & (B_NOCACHE | B_INVAL)) ||
2671 (bp->b_ioflags & BIO_ERROR) || (bp->b_bufsize <= 0)) {
2673 * Either a failed read I/O, or we were asked to free or not
2674 * cache the buffer, or we failed to write to a device that's
2675 * no longer present.
2677 bp->b_flags |= B_INVAL;
2678 if (!LIST_EMPTY(&bp->b_dep))
2680 if (bp->b_flags & B_DELWRI)
2682 bp->b_flags &= ~(B_DELWRI | B_CACHE);
2683 if ((bp->b_flags & B_VMIO) == 0) {
2691 * We must clear B_RELBUF if B_DELWRI is set. If vfs_vmio_truncate()
2692 * is called with B_DELWRI set, the underlying pages may wind up
2693 * getting freed causing a previous write (bdwrite()) to get 'lost'
2694 * because pages associated with a B_DELWRI bp are marked clean.
2696 * We still allow the B_INVAL case to call vfs_vmio_truncate(), even
2697 * if B_DELWRI is set.
2699 if (bp->b_flags & B_DELWRI)
2700 bp->b_flags &= ~B_RELBUF;
2703 * VMIO buffer rundown. It is not very necessary to keep a VMIO buffer
2704 * constituted, not even NFS buffers now. Two flags effect this. If
2705 * B_INVAL, the struct buf is invalidated but the VM object is kept
2706 * around ( i.e. so it is trivial to reconstitute the buffer later ).
2708 * If BIO_ERROR or B_NOCACHE is set, pages in the VM object will be
2709 * invalidated. BIO_ERROR cannot be set for a failed write unless the
2710 * buffer is also B_INVAL because it hits the re-dirtying code above.
2712 * Normally we can do this whether a buffer is B_DELWRI or not. If
2713 * the buffer is an NFS buffer, it is tracking piecemeal writes or
2714 * the commit state and we cannot afford to lose the buffer. If the
2715 * buffer has a background write in progress, we need to keep it
2716 * around to prevent it from being reconstituted and starting a second
2720 v_mnt = bp->b_vp != NULL ? bp->b_vp->v_mount : NULL;
2722 if ((bp->b_flags & B_VMIO) && (bp->b_flags & B_NOCACHE ||
2723 (bp->b_ioflags & BIO_ERROR && bp->b_iocmd == BIO_READ)) &&
2724 (v_mnt == NULL || (v_mnt->mnt_vfc->vfc_flags & VFCF_NETWORK) == 0 ||
2725 vn_isdisk(bp->b_vp, NULL) || (bp->b_flags & B_DELWRI) == 0)) {
2726 vfs_vmio_invalidate(bp);
2730 if ((bp->b_flags & (B_INVAL | B_RELBUF)) != 0 ||
2731 (bp->b_flags & (B_DELWRI | B_NOREUSE)) == B_NOREUSE) {
2733 bp->b_flags &= ~B_NOREUSE;
2734 if (bp->b_vp != NULL)
2739 * If the buffer has junk contents signal it and eventually
2740 * clean up B_DELWRI and diassociate the vnode so that gbincore()
2743 if (bp->b_bufsize == 0 || (bp->b_ioflags & BIO_ERROR) != 0 ||
2744 (bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF)) != 0)
2745 bp->b_flags |= B_INVAL;
2746 if (bp->b_flags & B_INVAL) {
2747 if (bp->b_flags & B_DELWRI)
2753 buf_track(bp, __func__);
2755 /* buffers with no memory */
2756 if (bp->b_bufsize == 0) {
2760 /* buffers with junk contents */
2761 if (bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF) ||
2762 (bp->b_ioflags & BIO_ERROR)) {
2763 bp->b_xflags &= ~(BX_BKGRDWRITE | BX_ALTDATA);
2764 if (bp->b_vflags & BV_BKGRDINPROG)
2765 panic("losing buffer 2");
2766 qindex = QUEUE_CLEAN;
2767 bp->b_flags |= B_AGE;
2768 /* remaining buffers */
2769 } else if (bp->b_flags & B_DELWRI)
2770 qindex = QUEUE_DIRTY;
2772 qindex = QUEUE_CLEAN;
2774 if ((bp->b_flags & B_DELWRI) == 0 && (bp->b_xflags & BX_VNDIRTY))
2775 panic("brelse: not dirty");
2777 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_RELBUF | B_DIRECT);
2778 /* binsfree unlocks bp. */
2779 binsfree(bp, qindex);
2783 * Release a buffer back to the appropriate queue but do not try to free
2784 * it. The buffer is expected to be used again soon.
2786 * bqrelse() is used by bdwrite() to requeue a delayed write, and used by
2787 * biodone() to requeue an async I/O on completion. It is also used when
2788 * known good buffers need to be requeued but we think we may need the data
2791 * XXX we should be able to leave the B_RELBUF hint set on completion.
2794 bqrelse(struct buf *bp)
2798 CTR3(KTR_BUF, "bqrelse(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
2799 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)),
2800 ("bqrelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp));
2802 qindex = QUEUE_NONE;
2803 if (BUF_LOCKRECURSED(bp)) {
2804 /* do not release to free list */
2808 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF);
2810 if (bp->b_flags & B_MANAGED) {
2811 if (bp->b_flags & B_REMFREE)
2816 /* buffers with stale but valid contents */
2817 if ((bp->b_flags & B_DELWRI) != 0 || (bp->b_vflags & (BV_BKGRDINPROG |
2818 BV_BKGRDERR)) == BV_BKGRDERR) {
2819 BO_LOCK(bp->b_bufobj);
2820 bp->b_vflags &= ~BV_BKGRDERR;
2821 BO_UNLOCK(bp->b_bufobj);
2822 qindex = QUEUE_DIRTY;
2824 if ((bp->b_flags & B_DELWRI) == 0 &&
2825 (bp->b_xflags & BX_VNDIRTY))
2826 panic("bqrelse: not dirty");
2827 if ((bp->b_flags & B_NOREUSE) != 0) {
2831 qindex = QUEUE_CLEAN;
2833 buf_track(bp, __func__);
2834 /* binsfree unlocks bp. */
2835 binsfree(bp, qindex);
2839 buf_track(bp, __func__);
2845 * Complete I/O to a VMIO backed page. Validate the pages as appropriate,
2846 * restore bogus pages.
2849 vfs_vmio_iodone(struct buf *bp)
2854 struct vnode *vp __unused;
2855 int i, iosize, resid;
2858 obj = bp->b_bufobj->bo_object;
2859 KASSERT(REFCOUNT_COUNT(obj->paging_in_progress) >= bp->b_npages,
2860 ("vfs_vmio_iodone: paging in progress(%d) < b_npages(%d)",
2861 REFCOUNT_COUNT(obj->paging_in_progress), bp->b_npages));
2864 KASSERT(vp->v_holdcnt > 0,
2865 ("vfs_vmio_iodone: vnode %p has zero hold count", vp));
2866 KASSERT(vp->v_object != NULL,
2867 ("vfs_vmio_iodone: vnode %p has no vm_object", vp));
2869 foff = bp->b_offset;
2870 KASSERT(bp->b_offset != NOOFFSET,
2871 ("vfs_vmio_iodone: bp %p has no buffer offset", bp));
2874 iosize = bp->b_bcount - bp->b_resid;
2875 for (i = 0; i < bp->b_npages; i++) {
2876 resid = ((foff + PAGE_SIZE) & ~(off_t)PAGE_MASK) - foff;
2881 * cleanup bogus pages, restoring the originals
2884 if (m == bogus_page) {
2885 if (bogus == false) {
2887 VM_OBJECT_RLOCK(obj);
2889 m = vm_page_lookup(obj, OFF_TO_IDX(foff));
2891 panic("biodone: page disappeared!");
2893 } else if ((bp->b_iocmd == BIO_READ) && resid > 0) {
2895 * In the write case, the valid and clean bits are
2896 * already changed correctly ( see bdwrite() ), so we
2897 * only need to do this here in the read case.
2899 KASSERT((m->dirty & vm_page_bits(foff & PAGE_MASK,
2900 resid)) == 0, ("vfs_vmio_iodone: page %p "
2901 "has unexpected dirty bits", m));
2902 vfs_page_set_valid(bp, foff, m);
2904 KASSERT(OFF_TO_IDX(foff) == m->pindex,
2905 ("vfs_vmio_iodone: foff(%jd)/pindex(%ju) mismatch",
2906 (intmax_t)foff, (uintmax_t)m->pindex));
2909 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK;
2913 VM_OBJECT_RUNLOCK(obj);
2914 vm_object_pip_wakeupn(obj, bp->b_npages);
2915 if (bogus && buf_mapped(bp)) {
2916 BUF_CHECK_MAPPED(bp);
2917 pmap_qenter(trunc_page((vm_offset_t)bp->b_data),
2918 bp->b_pages, bp->b_npages);
2923 * Perform page invalidation when a buffer is released. The fully invalid
2924 * pages will be reclaimed later in vfs_vmio_truncate().
2927 vfs_vmio_invalidate(struct buf *bp)
2931 int flags, i, resid, poffset, presid;
2933 if (buf_mapped(bp)) {
2934 BUF_CHECK_MAPPED(bp);
2935 pmap_qremove(trunc_page((vm_offset_t)bp->b_data), bp->b_npages);
2937 BUF_CHECK_UNMAPPED(bp);
2939 * Get the base offset and length of the buffer. Note that
2940 * in the VMIO case if the buffer block size is not
2941 * page-aligned then b_data pointer may not be page-aligned.
2942 * But our b_pages[] array *IS* page aligned.
2944 * block sizes less then DEV_BSIZE (usually 512) are not
2945 * supported due to the page granularity bits (m->valid,
2946 * m->dirty, etc...).
2948 * See man buf(9) for more information
2950 flags = (bp->b_flags & B_NOREUSE) != 0 ? VPR_NOREUSE : 0;
2951 obj = bp->b_bufobj->bo_object;
2952 resid = bp->b_bufsize;
2953 poffset = bp->b_offset & PAGE_MASK;
2954 VM_OBJECT_WLOCK(obj);
2955 for (i = 0; i < bp->b_npages; i++) {
2957 if (m == bogus_page)
2958 panic("vfs_vmio_invalidate: Unexpected bogus page.");
2959 bp->b_pages[i] = NULL;
2961 presid = resid > (PAGE_SIZE - poffset) ?
2962 (PAGE_SIZE - poffset) : resid;
2963 KASSERT(presid >= 0, ("brelse: extra page"));
2964 vm_page_busy_acquire(m, VM_ALLOC_SBUSY);
2965 if (pmap_page_wired_mappings(m) == 0)
2966 vm_page_set_invalid(m, poffset, presid);
2968 vm_page_release_locked(m, flags);
2972 VM_OBJECT_WUNLOCK(obj);
2977 * Page-granular truncation of an existing VMIO buffer.
2980 vfs_vmio_truncate(struct buf *bp, int desiredpages)
2986 if (bp->b_npages == desiredpages)
2989 if (buf_mapped(bp)) {
2990 BUF_CHECK_MAPPED(bp);
2991 pmap_qremove((vm_offset_t)trunc_page((vm_offset_t)bp->b_data) +
2992 (desiredpages << PAGE_SHIFT), bp->b_npages - desiredpages);
2994 BUF_CHECK_UNMAPPED(bp);
2997 * The object lock is needed only if we will attempt to free pages.
2999 flags = (bp->b_flags & B_NOREUSE) != 0 ? VPR_NOREUSE : 0;
3000 if ((bp->b_flags & B_DIRECT) != 0) {
3001 flags |= VPR_TRYFREE;
3002 obj = bp->b_bufobj->bo_object;
3003 VM_OBJECT_WLOCK(obj);
3007 for (i = desiredpages; i < bp->b_npages; i++) {
3009 KASSERT(m != bogus_page, ("allocbuf: bogus page found"));
3010 bp->b_pages[i] = NULL;
3012 vm_page_release_locked(m, flags);
3014 vm_page_release(m, flags);
3017 VM_OBJECT_WUNLOCK(obj);
3018 bp->b_npages = desiredpages;
3022 * Byte granular extension of VMIO buffers.
3025 vfs_vmio_extend(struct buf *bp, int desiredpages, int size)
3028 * We are growing the buffer, possibly in a
3029 * byte-granular fashion.
3037 * Step 1, bring in the VM pages from the object, allocating
3038 * them if necessary. We must clear B_CACHE if these pages
3039 * are not valid for the range covered by the buffer.
3041 obj = bp->b_bufobj->bo_object;
3042 if (bp->b_npages < desiredpages) {
3044 * We must allocate system pages since blocking
3045 * here could interfere with paging I/O, no
3046 * matter which process we are.
3048 * Only exclusive busy can be tested here.
3049 * Blocking on shared busy might lead to
3050 * deadlocks once allocbuf() is called after
3051 * pages are vfs_busy_pages().
3053 VM_OBJECT_WLOCK(obj);
3054 (void)vm_page_grab_pages(obj,
3055 OFF_TO_IDX(bp->b_offset) + bp->b_npages,
3056 VM_ALLOC_SYSTEM | VM_ALLOC_IGN_SBUSY |
3057 VM_ALLOC_NOBUSY | VM_ALLOC_WIRED,
3058 &bp->b_pages[bp->b_npages], desiredpages - bp->b_npages);
3059 VM_OBJECT_WUNLOCK(obj);
3060 bp->b_npages = desiredpages;
3064 * Step 2. We've loaded the pages into the buffer,
3065 * we have to figure out if we can still have B_CACHE
3066 * set. Note that B_CACHE is set according to the
3067 * byte-granular range ( bcount and size ), not the
3068 * aligned range ( newbsize ).
3070 * The VM test is against m->valid, which is DEV_BSIZE
3071 * aligned. Needless to say, the validity of the data
3072 * needs to also be DEV_BSIZE aligned. Note that this
3073 * fails with NFS if the server or some other client
3074 * extends the file's EOF. If our buffer is resized,
3075 * B_CACHE may remain set! XXX
3077 toff = bp->b_bcount;
3078 tinc = PAGE_SIZE - ((bp->b_offset + toff) & PAGE_MASK);
3079 while ((bp->b_flags & B_CACHE) && toff < size) {
3082 if (tinc > (size - toff))
3084 pi = ((bp->b_offset & PAGE_MASK) + toff) >> PAGE_SHIFT;
3085 m = bp->b_pages[pi];
3086 vfs_buf_test_cache(bp, bp->b_offset, toff, tinc, m);
3092 * Step 3, fixup the KVA pmap.
3097 BUF_CHECK_UNMAPPED(bp);
3101 * Check to see if a block at a particular lbn is available for a clustered
3105 vfs_bio_clcheck(struct vnode *vp, int size, daddr_t lblkno, daddr_t blkno)
3112 /* If the buf isn't in core skip it */
3113 if ((bpa = gbincore(&vp->v_bufobj, lblkno)) == NULL)
3116 /* If the buf is busy we don't want to wait for it */
3117 if (BUF_LOCK(bpa, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0)
3120 /* Only cluster with valid clusterable delayed write buffers */
3121 if ((bpa->b_flags & (B_DELWRI | B_CLUSTEROK | B_INVAL)) !=
3122 (B_DELWRI | B_CLUSTEROK))
3125 if (bpa->b_bufsize != size)
3129 * Check to see if it is in the expected place on disk and that the
3130 * block has been mapped.
3132 if ((bpa->b_blkno != bpa->b_lblkno) && (bpa->b_blkno == blkno))
3142 * Implement clustered async writes for clearing out B_DELWRI buffers.
3143 * This is much better then the old way of writing only one buffer at
3144 * a time. Note that we may not be presented with the buffers in the
3145 * correct order, so we search for the cluster in both directions.
3148 vfs_bio_awrite(struct buf *bp)
3153 daddr_t lblkno = bp->b_lblkno;
3154 struct vnode *vp = bp->b_vp;
3162 gbflags = (bp->b_data == unmapped_buf) ? GB_UNMAPPED : 0;
3164 * right now we support clustered writing only to regular files. If
3165 * we find a clusterable block we could be in the middle of a cluster
3166 * rather then at the beginning.
3168 if ((vp->v_type == VREG) &&
3169 (vp->v_mount != 0) && /* Only on nodes that have the size info */
3170 (bp->b_flags & (B_CLUSTEROK | B_INVAL)) == B_CLUSTEROK) {
3172 size = vp->v_mount->mnt_stat.f_iosize;
3173 maxcl = MAXPHYS / size;
3176 for (i = 1; i < maxcl; i++)
3177 if (vfs_bio_clcheck(vp, size, lblkno + i,
3178 bp->b_blkno + ((i * size) >> DEV_BSHIFT)) == 0)
3181 for (j = 1; i + j <= maxcl && j <= lblkno; j++)
3182 if (vfs_bio_clcheck(vp, size, lblkno - j,
3183 bp->b_blkno - ((j * size) >> DEV_BSHIFT)) == 0)
3189 * this is a possible cluster write
3193 nwritten = cluster_wbuild(vp, size, lblkno - j, ncl,
3199 bp->b_flags |= B_ASYNC;
3201 * default (old) behavior, writing out only one block
3203 * XXX returns b_bufsize instead of b_bcount for nwritten?
3205 nwritten = bp->b_bufsize;
3214 * Allocate KVA for an empty buf header according to gbflags.
3217 getnewbuf_kva(struct buf *bp, int gbflags, int maxsize)
3220 if ((gbflags & (GB_UNMAPPED | GB_KVAALLOC)) != GB_UNMAPPED) {
3222 * In order to keep fragmentation sane we only allocate kva
3223 * in BKVASIZE chunks. XXX with vmem we can do page size.
3225 maxsize = (maxsize + BKVAMASK) & ~BKVAMASK;
3227 if (maxsize != bp->b_kvasize &&
3228 bufkva_alloc(bp, maxsize, gbflags))
3237 * Find and initialize a new buffer header, freeing up existing buffers
3238 * in the bufqueues as necessary. The new buffer is returned locked.
3241 * We have insufficient buffer headers
3242 * We have insufficient buffer space
3243 * buffer_arena is too fragmented ( space reservation fails )
3244 * If we have to flush dirty buffers ( but we try to avoid this )
3246 * The caller is responsible for releasing the reserved bufspace after
3247 * allocbuf() is called.
3250 getnewbuf(struct vnode *vp, int slpflag, int slptimeo, int maxsize, int gbflags)
3252 struct bufdomain *bd;
3254 bool metadata, reserved;
3257 KASSERT((gbflags & (GB_UNMAPPED | GB_KVAALLOC)) != GB_KVAALLOC,
3258 ("GB_KVAALLOC only makes sense with GB_UNMAPPED"));
3259 if (!unmapped_buf_allowed)
3260 gbflags &= ~(GB_UNMAPPED | GB_KVAALLOC);
3262 if (vp == NULL || (vp->v_vflag & (VV_MD | VV_SYSTEM)) != 0 ||
3270 bd = &bdomain[vp->v_bufobj.bo_domain];
3272 counter_u64_add(getnewbufcalls, 1);
3275 if (reserved == false &&
3276 bufspace_reserve(bd, maxsize, metadata) != 0) {
3277 counter_u64_add(getnewbufrestarts, 1);
3281 if ((bp = buf_alloc(bd)) == NULL) {
3282 counter_u64_add(getnewbufrestarts, 1);
3285 if (getnewbuf_kva(bp, gbflags, maxsize) == 0)
3288 } while (buf_recycle(bd, false) == 0);
3291 bufspace_release(bd, maxsize);
3293 bp->b_flags |= B_INVAL;
3296 bufspace_wait(bd, vp, gbflags, slpflag, slptimeo);
3304 * buffer flushing daemon. Buffers are normally flushed by the
3305 * update daemon but if it cannot keep up this process starts to
3306 * take the load in an attempt to prevent getnewbuf() from blocking.
3308 static struct kproc_desc buf_kp = {
3313 SYSINIT(bufdaemon, SI_SUB_KTHREAD_BUF, SI_ORDER_FIRST, kproc_start, &buf_kp);
3316 buf_flush(struct vnode *vp, struct bufdomain *bd, int target)
3320 flushed = flushbufqueues(vp, bd, target, 0);
3323 * Could not find any buffers without rollback
3324 * dependencies, so just write the first one
3325 * in the hopes of eventually making progress.
3327 if (vp != NULL && target > 2)
3329 flushbufqueues(vp, bd, target, 1);
3337 struct bufdomain *bd;
3343 * This process needs to be suspended prior to shutdown sync.
3345 EVENTHANDLER_REGISTER(shutdown_pre_sync, kthread_shutdown, curthread,
3346 SHUTDOWN_PRI_LAST + 100);
3349 * Start the buf clean daemons as children threads.
3351 for (i = 0 ; i < buf_domains; i++) {
3354 error = kthread_add((void (*)(void *))bufspace_daemon,
3355 &bdomain[i], curproc, NULL, 0, 0, "bufspacedaemon-%d", i);
3357 panic("error %d spawning bufspace daemon", error);
3361 * This process is allowed to take the buffer cache to the limit
3363 curthread->td_pflags |= TDP_NORUNNINGBUF | TDP_BUFNEED;
3367 mtx_unlock(&bdlock);
3369 kthread_suspend_check();
3372 * Save speedupreq for this pass and reset to capture new
3375 speedupreq = bd_speedupreq;
3379 * Flush each domain sequentially according to its level and
3380 * the speedup request.
3382 for (i = 0; i < buf_domains; i++) {
3385 lodirty = bd->bd_numdirtybuffers / 2;
3387 lodirty = bd->bd_lodirtybuffers;
3388 while (bd->bd_numdirtybuffers > lodirty) {
3389 if (buf_flush(NULL, bd,
3390 bd->bd_numdirtybuffers - lodirty) == 0)
3392 kern_yield(PRI_USER);
3397 * Only clear bd_request if we have reached our low water
3398 * mark. The buf_daemon normally waits 1 second and
3399 * then incrementally flushes any dirty buffers that have
3400 * built up, within reason.
3402 * If we were unable to hit our low water mark and couldn't
3403 * find any flushable buffers, we sleep for a short period
3404 * to avoid endless loops on unlockable buffers.
3407 if (!BIT_EMPTY(BUF_DOMAINS, &bdlodirty)) {
3409 * We reached our low water mark, reset the
3410 * request and sleep until we are needed again.
3411 * The sleep is just so the suspend code works.
3415 * Do an extra wakeup in case dirty threshold
3416 * changed via sysctl and the explicit transition
3417 * out of shortfall was missed.
3420 if (runningbufspace <= lorunningspace)
3422 msleep(&bd_request, &bdlock, PVM, "psleep", hz);
3425 * We couldn't find any flushable dirty buffers but
3426 * still have too many dirty buffers, we
3427 * have to sleep and try again. (rare)
3429 msleep(&bd_request, &bdlock, PVM, "qsleep", hz / 10);
3437 * Try to flush a buffer in the dirty queue. We must be careful to
3438 * free up B_INVAL buffers instead of write them, which NFS is
3439 * particularly sensitive to.
3441 static int flushwithdeps = 0;
3442 SYSCTL_INT(_vfs, OID_AUTO, flushwithdeps, CTLFLAG_RW | CTLFLAG_STATS,
3444 "Number of buffers flushed with dependecies that require rollbacks");
3447 flushbufqueues(struct vnode *lvp, struct bufdomain *bd, int target,
3450 struct bufqueue *bq;
3451 struct buf *sentinel;
3461 bq = &bd->bd_dirtyq;
3463 sentinel = malloc(sizeof(struct buf), M_TEMP, M_WAITOK | M_ZERO);
3464 sentinel->b_qindex = QUEUE_SENTINEL;
3466 TAILQ_INSERT_HEAD(&bq->bq_queue, sentinel, b_freelist);
3468 while (flushed != target) {
3471 bp = TAILQ_NEXT(sentinel, b_freelist);
3473 TAILQ_REMOVE(&bq->bq_queue, sentinel, b_freelist);
3474 TAILQ_INSERT_AFTER(&bq->bq_queue, bp, sentinel,
3481 * Skip sentinels inserted by other invocations of the
3482 * flushbufqueues(), taking care to not reorder them.
3484 * Only flush the buffers that belong to the
3485 * vnode locked by the curthread.
3487 if (bp->b_qindex == QUEUE_SENTINEL || (lvp != NULL &&
3492 error = BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL);
3498 * BKGRDINPROG can only be set with the buf and bufobj
3499 * locks both held. We tolerate a race to clear it here.
3501 if ((bp->b_vflags & BV_BKGRDINPROG) != 0 ||
3502 (bp->b_flags & B_DELWRI) == 0) {
3506 if (bp->b_flags & B_INVAL) {
3513 if (!LIST_EMPTY(&bp->b_dep) && buf_countdeps(bp, 0)) {
3514 if (flushdeps == 0) {
3522 * We must hold the lock on a vnode before writing
3523 * one of its buffers. Otherwise we may confuse, or
3524 * in the case of a snapshot vnode, deadlock the
3527 * The lock order here is the reverse of the normal
3528 * of vnode followed by buf lock. This is ok because
3529 * the NOWAIT will prevent deadlock.
3532 if (vn_start_write(vp, &mp, V_NOWAIT) != 0) {
3538 error = vn_lock(vp, LK_EXCLUSIVE | LK_NOWAIT);
3540 ASSERT_VOP_LOCKED(vp, "getbuf");
3542 error = VOP_ISLOCKED(vp) == LK_EXCLUSIVE ? 0 :
3543 vn_lock(vp, LK_TRYUPGRADE);
3546 CTR3(KTR_BUF, "flushbufqueue(%p) vp %p flags %X",
3547 bp, bp->b_vp, bp->b_flags);
3548 if (curproc == bufdaemonproc) {
3553 counter_u64_add(notbufdflushes, 1);
3555 vn_finished_write(mp);
3558 flushwithdeps += hasdeps;
3562 * Sleeping on runningbufspace while holding
3563 * vnode lock leads to deadlock.
3565 if (curproc == bufdaemonproc &&
3566 runningbufspace > hirunningspace)
3567 waitrunningbufspace();
3570 vn_finished_write(mp);
3574 TAILQ_REMOVE(&bq->bq_queue, sentinel, b_freelist);
3576 free(sentinel, M_TEMP);
3581 * Check to see if a block is currently memory resident.
3584 incore(struct bufobj *bo, daddr_t blkno)
3589 bp = gbincore(bo, blkno);
3595 * Returns true if no I/O is needed to access the
3596 * associated VM object. This is like incore except
3597 * it also hunts around in the VM system for the data.
3601 inmem(struct vnode * vp, daddr_t blkno)
3604 vm_offset_t toff, tinc, size;
3608 ASSERT_VOP_LOCKED(vp, "inmem");
3610 if (incore(&vp->v_bufobj, blkno))
3612 if (vp->v_mount == NULL)
3619 if (size > vp->v_mount->mnt_stat.f_iosize)
3620 size = vp->v_mount->mnt_stat.f_iosize;
3621 off = (vm_ooffset_t)blkno * (vm_ooffset_t)vp->v_mount->mnt_stat.f_iosize;
3623 VM_OBJECT_RLOCK(obj);
3624 for (toff = 0; toff < vp->v_mount->mnt_stat.f_iosize; toff += tinc) {
3625 m = vm_page_lookup(obj, OFF_TO_IDX(off + toff));
3629 if (tinc > PAGE_SIZE - ((toff + off) & PAGE_MASK))
3630 tinc = PAGE_SIZE - ((toff + off) & PAGE_MASK);
3631 if (vm_page_is_valid(m,
3632 (vm_offset_t) ((toff + off) & PAGE_MASK), tinc) == 0)
3635 VM_OBJECT_RUNLOCK(obj);
3639 VM_OBJECT_RUNLOCK(obj);
3644 * Set the dirty range for a buffer based on the status of the dirty
3645 * bits in the pages comprising the buffer. The range is limited
3646 * to the size of the buffer.
3648 * Tell the VM system that the pages associated with this buffer
3649 * are clean. This is used for delayed writes where the data is
3650 * going to go to disk eventually without additional VM intevention.
3652 * Note that while we only really need to clean through to b_bcount, we
3653 * just go ahead and clean through to b_bufsize.
3656 vfs_clean_pages_dirty_buf(struct buf *bp)
3658 vm_ooffset_t foff, noff, eoff;
3662 if ((bp->b_flags & B_VMIO) == 0 || bp->b_bufsize == 0)
3665 foff = bp->b_offset;
3666 KASSERT(bp->b_offset != NOOFFSET,
3667 ("vfs_clean_pages_dirty_buf: no buffer offset"));
3669 vfs_busy_pages_acquire(bp);
3670 vfs_setdirty_range(bp);
3671 for (i = 0; i < bp->b_npages; i++) {
3672 noff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK;
3674 if (eoff > bp->b_offset + bp->b_bufsize)
3675 eoff = bp->b_offset + bp->b_bufsize;
3677 vfs_page_set_validclean(bp, foff, m);
3678 /* vm_page_clear_dirty(m, foff & PAGE_MASK, eoff - foff); */
3681 vfs_busy_pages_release(bp);
3685 vfs_setdirty_range(struct buf *bp)
3687 vm_offset_t boffset;
3688 vm_offset_t eoffset;
3692 * test the pages to see if they have been modified directly
3693 * by users through the VM system.
3695 for (i = 0; i < bp->b_npages; i++)
3696 vm_page_test_dirty(bp->b_pages[i]);
3699 * Calculate the encompassing dirty range, boffset and eoffset,
3700 * (eoffset - boffset) bytes.
3703 for (i = 0; i < bp->b_npages; i++) {
3704 if (bp->b_pages[i]->dirty)
3707 boffset = (i << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK);
3709 for (i = bp->b_npages - 1; i >= 0; --i) {
3710 if (bp->b_pages[i]->dirty) {
3714 eoffset = ((i + 1) << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK);
3717 * Fit it to the buffer.
3720 if (eoffset > bp->b_bcount)
3721 eoffset = bp->b_bcount;
3724 * If we have a good dirty range, merge with the existing
3728 if (boffset < eoffset) {
3729 if (bp->b_dirtyoff > boffset)
3730 bp->b_dirtyoff = boffset;
3731 if (bp->b_dirtyend < eoffset)
3732 bp->b_dirtyend = eoffset;
3737 * Allocate the KVA mapping for an existing buffer.
3738 * If an unmapped buffer is provided but a mapped buffer is requested, take
3739 * also care to properly setup mappings between pages and KVA.
3742 bp_unmapped_get_kva(struct buf *bp, daddr_t blkno, int size, int gbflags)
3744 int bsize, maxsize, need_mapping, need_kva;
3747 need_mapping = bp->b_data == unmapped_buf &&
3748 (gbflags & GB_UNMAPPED) == 0;
3749 need_kva = bp->b_kvabase == unmapped_buf &&
3750 bp->b_data == unmapped_buf &&
3751 (gbflags & GB_KVAALLOC) != 0;
3752 if (!need_mapping && !need_kva)
3755 BUF_CHECK_UNMAPPED(bp);
3757 if (need_mapping && bp->b_kvabase != unmapped_buf) {
3759 * Buffer is not mapped, but the KVA was already
3760 * reserved at the time of the instantiation. Use the
3767 * Calculate the amount of the address space we would reserve
3768 * if the buffer was mapped.
3770 bsize = vn_isdisk(bp->b_vp, NULL) ? DEV_BSIZE : bp->b_bufobj->bo_bsize;
3771 KASSERT(bsize != 0, ("bsize == 0, check bo->bo_bsize"));
3772 offset = blkno * bsize;
3773 maxsize = size + (offset & PAGE_MASK);
3774 maxsize = imax(maxsize, bsize);
3776 while (bufkva_alloc(bp, maxsize, gbflags) != 0) {
3777 if ((gbflags & GB_NOWAIT_BD) != 0) {
3779 * XXXKIB: defragmentation cannot
3780 * succeed, not sure what else to do.
3782 panic("GB_NOWAIT_BD and GB_UNMAPPED %p", bp);
3784 counter_u64_add(mappingrestarts, 1);
3785 bufspace_wait(bufdomain(bp), bp->b_vp, gbflags, 0, 0);
3789 /* b_offset is handled by bpmap_qenter. */
3790 bp->b_data = bp->b_kvabase;
3791 BUF_CHECK_MAPPED(bp);
3797 getblk(struct vnode *vp, daddr_t blkno, int size, int slpflag, int slptimeo,
3803 error = getblkx(vp, blkno, blkno, size, slpflag, slptimeo, flags, &bp);
3812 * Get a block given a specified block and offset into a file/device.
3813 * The buffers B_DONE bit will be cleared on return, making it almost
3814 * ready for an I/O initiation. B_INVAL may or may not be set on
3815 * return. The caller should clear B_INVAL prior to initiating a
3818 * For a non-VMIO buffer, B_CACHE is set to the opposite of B_INVAL for
3819 * an existing buffer.
3821 * For a VMIO buffer, B_CACHE is modified according to the backing VM.
3822 * If getblk()ing a previously 0-sized invalid buffer, B_CACHE is set
3823 * and then cleared based on the backing VM. If the previous buffer is
3824 * non-0-sized but invalid, B_CACHE will be cleared.
3826 * If getblk() must create a new buffer, the new buffer is returned with
3827 * both B_INVAL and B_CACHE clear unless it is a VMIO buffer, in which
3828 * case it is returned with B_INVAL clear and B_CACHE set based on the
3831 * getblk() also forces a bwrite() for any B_DELWRI buffer whose
3832 * B_CACHE bit is clear.
3834 * What this means, basically, is that the caller should use B_CACHE to
3835 * determine whether the buffer is fully valid or not and should clear
3836 * B_INVAL prior to issuing a read. If the caller intends to validate
3837 * the buffer by loading its data area with something, the caller needs
3838 * to clear B_INVAL. If the caller does this without issuing an I/O,
3839 * the caller should set B_CACHE ( as an optimization ), else the caller
3840 * should issue the I/O and biodone() will set B_CACHE if the I/O was
3841 * a write attempt or if it was a successful read. If the caller
3842 * intends to issue a READ, the caller must clear B_INVAL and BIO_ERROR
3843 * prior to issuing the READ. biodone() will *not* clear B_INVAL.
3845 * The blkno parameter is the logical block being requested. Normally
3846 * the mapping of logical block number to disk block address is done
3847 * by calling VOP_BMAP(). However, if the mapping is already known, the
3848 * disk block address can be passed using the dblkno parameter. If the
3849 * disk block address is not known, then the same value should be passed
3850 * for blkno and dblkno.
3853 getblkx(struct vnode *vp, daddr_t blkno, daddr_t dblkno, int size, int slpflag,
3854 int slptimeo, int flags, struct buf **bpp)
3859 int bsize, error, maxsize, vmio;
3862 CTR3(KTR_BUF, "getblk(%p, %ld, %d)", vp, (long)blkno, size);
3863 KASSERT((flags & (GB_UNMAPPED | GB_KVAALLOC)) != GB_KVAALLOC,
3864 ("GB_KVAALLOC only makes sense with GB_UNMAPPED"));
3865 ASSERT_VOP_LOCKED(vp, "getblk");
3866 if (size > maxbcachebuf)
3867 panic("getblk: size(%d) > maxbcachebuf(%d)\n", size,
3869 if (!unmapped_buf_allowed)
3870 flags &= ~(GB_UNMAPPED | GB_KVAALLOC);
3876 bp = gbincore(bo, blkno);
3880 * Buffer is in-core. If the buffer is not busy nor managed,
3881 * it must be on a queue.
3883 lockflags = LK_EXCLUSIVE | LK_SLEEPFAIL | LK_INTERLOCK;
3885 if ((flags & GB_LOCK_NOWAIT) != 0)
3886 lockflags |= LK_NOWAIT;
3888 error = BUF_TIMELOCK(bp, lockflags,
3889 BO_LOCKPTR(bo), "getblk", slpflag, slptimeo);
3892 * If we slept and got the lock we have to restart in case
3893 * the buffer changed identities.
3895 if (error == ENOLCK)
3897 /* We timed out or were interrupted. */
3898 else if (error != 0)
3900 /* If recursed, assume caller knows the rules. */
3901 else if (BUF_LOCKRECURSED(bp))
3905 * The buffer is locked. B_CACHE is cleared if the buffer is
3906 * invalid. Otherwise, for a non-VMIO buffer, B_CACHE is set
3907 * and for a VMIO buffer B_CACHE is adjusted according to the
3910 if (bp->b_flags & B_INVAL)
3911 bp->b_flags &= ~B_CACHE;
3912 else if ((bp->b_flags & (B_VMIO | B_INVAL)) == 0)
3913 bp->b_flags |= B_CACHE;
3914 if (bp->b_flags & B_MANAGED)
3915 MPASS(bp->b_qindex == QUEUE_NONE);
3920 * check for size inconsistencies for non-VMIO case.
3922 if (bp->b_bcount != size) {
3923 if ((bp->b_flags & B_VMIO) == 0 ||
3924 (size > bp->b_kvasize)) {
3925 if (bp->b_flags & B_DELWRI) {
3926 bp->b_flags |= B_NOCACHE;
3929 if (LIST_EMPTY(&bp->b_dep)) {
3930 bp->b_flags |= B_RELBUF;
3933 bp->b_flags |= B_NOCACHE;
3942 * Handle the case of unmapped buffer which should
3943 * become mapped, or the buffer for which KVA
3944 * reservation is requested.
3946 bp_unmapped_get_kva(bp, blkno, size, flags);
3949 * If the size is inconsistent in the VMIO case, we can resize
3950 * the buffer. This might lead to B_CACHE getting set or
3951 * cleared. If the size has not changed, B_CACHE remains
3952 * unchanged from its previous state.
3956 KASSERT(bp->b_offset != NOOFFSET,
3957 ("getblk: no buffer offset"));
3960 * A buffer with B_DELWRI set and B_CACHE clear must
3961 * be committed before we can return the buffer in
3962 * order to prevent the caller from issuing a read
3963 * ( due to B_CACHE not being set ) and overwriting
3966 * Most callers, including NFS and FFS, need this to
3967 * operate properly either because they assume they
3968 * can issue a read if B_CACHE is not set, or because
3969 * ( for example ) an uncached B_DELWRI might loop due
3970 * to softupdates re-dirtying the buffer. In the latter
3971 * case, B_CACHE is set after the first write completes,
3972 * preventing further loops.
3973 * NOTE! b*write() sets B_CACHE. If we cleared B_CACHE
3974 * above while extending the buffer, we cannot allow the
3975 * buffer to remain with B_CACHE set after the write
3976 * completes or it will represent a corrupt state. To
3977 * deal with this we set B_NOCACHE to scrap the buffer
3980 * We might be able to do something fancy, like setting
3981 * B_CACHE in bwrite() except if B_DELWRI is already set,
3982 * so the below call doesn't set B_CACHE, but that gets real
3983 * confusing. This is much easier.
3986 if ((bp->b_flags & (B_CACHE|B_DELWRI)) == B_DELWRI) {
3987 bp->b_flags |= B_NOCACHE;
3991 bp->b_flags &= ~B_DONE;
3994 * Buffer is not in-core, create new buffer. The buffer
3995 * returned by getnewbuf() is locked. Note that the returned
3996 * buffer is also considered valid (not marked B_INVAL).
4000 * If the user does not want us to create the buffer, bail out
4003 if (flags & GB_NOCREAT)
4006 bsize = vn_isdisk(vp, NULL) ? DEV_BSIZE : bo->bo_bsize;
4007 KASSERT(bsize != 0, ("bsize == 0, check bo->bo_bsize"));
4008 offset = blkno * bsize;
4009 vmio = vp->v_object != NULL;
4011 maxsize = size + (offset & PAGE_MASK);
4014 /* Do not allow non-VMIO notmapped buffers. */
4015 flags &= ~(GB_UNMAPPED | GB_KVAALLOC);
4017 maxsize = imax(maxsize, bsize);
4018 if ((flags & GB_NOSPARSE) != 0 && vmio &&
4019 !vn_isdisk(vp, NULL)) {
4020 error = VOP_BMAP(vp, blkno, NULL, &d_blkno, 0, 0);
4021 KASSERT(error != EOPNOTSUPP,
4022 ("GB_NOSPARSE from fs not supporting bmap, vp %p",
4027 return (EJUSTRETURN);
4030 bp = getnewbuf(vp, slpflag, slptimeo, maxsize, flags);
4032 if (slpflag || slptimeo)
4035 * XXX This is here until the sleep path is diagnosed
4036 * enough to work under very low memory conditions.
4038 * There's an issue on low memory, 4BSD+non-preempt
4039 * systems (eg MIPS routers with 32MB RAM) where buffer
4040 * exhaustion occurs without sleeping for buffer
4041 * reclaimation. This just sticks in a loop and
4042 * constantly attempts to allocate a buffer, which
4043 * hits exhaustion and tries to wakeup bufdaemon.
4044 * This never happens because we never yield.
4046 * The real solution is to identify and fix these cases
4047 * so we aren't effectively busy-waiting in a loop
4048 * until the reclaimation path has cycles to run.
4050 kern_yield(PRI_USER);
4055 * This code is used to make sure that a buffer is not
4056 * created while the getnewbuf routine is blocked.
4057 * This can be a problem whether the vnode is locked or not.
4058 * If the buffer is created out from under us, we have to
4059 * throw away the one we just created.
4061 * Note: this must occur before we associate the buffer
4062 * with the vp especially considering limitations in
4063 * the splay tree implementation when dealing with duplicate
4067 if (gbincore(bo, blkno)) {
4069 bp->b_flags |= B_INVAL;
4070 bufspace_release(bufdomain(bp), maxsize);
4076 * Insert the buffer into the hash, so that it can
4077 * be found by incore.
4079 bp->b_lblkno = blkno;
4080 bp->b_blkno = d_blkno;
4081 bp->b_offset = offset;
4086 * set B_VMIO bit. allocbuf() the buffer bigger. Since the
4087 * buffer size starts out as 0, B_CACHE will be set by
4088 * allocbuf() for the VMIO case prior to it testing the
4089 * backing store for validity.
4093 bp->b_flags |= B_VMIO;
4094 KASSERT(vp->v_object == bp->b_bufobj->bo_object,
4095 ("ARGH! different b_bufobj->bo_object %p %p %p\n",
4096 bp, vp->v_object, bp->b_bufobj->bo_object));
4098 bp->b_flags &= ~B_VMIO;
4099 KASSERT(bp->b_bufobj->bo_object == NULL,
4100 ("ARGH! has b_bufobj->bo_object %p %p\n",
4101 bp, bp->b_bufobj->bo_object));
4102 BUF_CHECK_MAPPED(bp);
4106 bufspace_release(bufdomain(bp), maxsize);
4107 bp->b_flags &= ~B_DONE;
4109 CTR4(KTR_BUF, "getblk(%p, %ld, %d) = %p", vp, (long)blkno, size, bp);
4111 buf_track(bp, __func__);
4112 KASSERT(bp->b_bufobj == bo,
4113 ("bp %p wrong b_bufobj %p should be %p", bp, bp->b_bufobj, bo));
4119 * Get an empty, disassociated buffer of given size. The buffer is initially
4123 geteblk(int size, int flags)
4128 maxsize = (size + BKVAMASK) & ~BKVAMASK;
4129 while ((bp = getnewbuf(NULL, 0, 0, maxsize, flags)) == NULL) {
4130 if ((flags & GB_NOWAIT_BD) &&
4131 (curthread->td_pflags & TDP_BUFNEED) != 0)
4135 bufspace_release(bufdomain(bp), maxsize);
4136 bp->b_flags |= B_INVAL; /* b_dep cleared by getnewbuf() */
4141 * Truncate the backing store for a non-vmio buffer.
4144 vfs_nonvmio_truncate(struct buf *bp, int newbsize)
4147 if (bp->b_flags & B_MALLOC) {
4149 * malloced buffers are not shrunk
4151 if (newbsize == 0) {
4152 bufmallocadjust(bp, 0);
4153 free(bp->b_data, M_BIOBUF);
4154 bp->b_data = bp->b_kvabase;
4155 bp->b_flags &= ~B_MALLOC;
4159 vm_hold_free_pages(bp, newbsize);
4160 bufspace_adjust(bp, newbsize);
4164 * Extend the backing for a non-VMIO buffer.
4167 vfs_nonvmio_extend(struct buf *bp, int newbsize)
4173 * We only use malloced memory on the first allocation.
4174 * and revert to page-allocated memory when the buffer
4177 * There is a potential smp race here that could lead
4178 * to bufmallocspace slightly passing the max. It
4179 * is probably extremely rare and not worth worrying
4182 if (bp->b_bufsize == 0 && newbsize <= PAGE_SIZE/2 &&
4183 bufmallocspace < maxbufmallocspace) {
4184 bp->b_data = malloc(newbsize, M_BIOBUF, M_WAITOK);
4185 bp->b_flags |= B_MALLOC;
4186 bufmallocadjust(bp, newbsize);
4191 * If the buffer is growing on its other-than-first
4192 * allocation then we revert to the page-allocation
4197 if (bp->b_flags & B_MALLOC) {
4198 origbuf = bp->b_data;
4199 origbufsize = bp->b_bufsize;
4200 bp->b_data = bp->b_kvabase;
4201 bufmallocadjust(bp, 0);
4202 bp->b_flags &= ~B_MALLOC;
4203 newbsize = round_page(newbsize);
4205 vm_hold_load_pages(bp, (vm_offset_t) bp->b_data + bp->b_bufsize,
4206 (vm_offset_t) bp->b_data + newbsize);
4207 if (origbuf != NULL) {
4208 bcopy(origbuf, bp->b_data, origbufsize);
4209 free(origbuf, M_BIOBUF);
4211 bufspace_adjust(bp, newbsize);
4215 * This code constitutes the buffer memory from either anonymous system
4216 * memory (in the case of non-VMIO operations) or from an associated
4217 * VM object (in the case of VMIO operations). This code is able to
4218 * resize a buffer up or down.
4220 * Note that this code is tricky, and has many complications to resolve
4221 * deadlock or inconsistent data situations. Tread lightly!!!
4222 * There are B_CACHE and B_DELWRI interactions that must be dealt with by
4223 * the caller. Calling this code willy nilly can result in the loss of data.
4225 * allocbuf() only adjusts B_CACHE for VMIO buffers. getblk() deals with
4226 * B_CACHE for the non-VMIO case.
4229 allocbuf(struct buf *bp, int size)
4233 if (bp->b_bcount == size)
4236 if (bp->b_kvasize != 0 && bp->b_kvasize < size)
4237 panic("allocbuf: buffer too small");
4239 newbsize = roundup2(size, DEV_BSIZE);
4240 if ((bp->b_flags & B_VMIO) == 0) {
4241 if ((bp->b_flags & B_MALLOC) == 0)
4242 newbsize = round_page(newbsize);
4244 * Just get anonymous memory from the kernel. Don't
4245 * mess with B_CACHE.
4247 if (newbsize < bp->b_bufsize)
4248 vfs_nonvmio_truncate(bp, newbsize);
4249 else if (newbsize > bp->b_bufsize)
4250 vfs_nonvmio_extend(bp, newbsize);
4254 desiredpages = (size == 0) ? 0 :
4255 num_pages((bp->b_offset & PAGE_MASK) + newbsize);
4257 if (bp->b_flags & B_MALLOC)
4258 panic("allocbuf: VMIO buffer can't be malloced");
4260 * Set B_CACHE initially if buffer is 0 length or will become
4263 if (size == 0 || bp->b_bufsize == 0)
4264 bp->b_flags |= B_CACHE;
4266 if (newbsize < bp->b_bufsize)
4267 vfs_vmio_truncate(bp, desiredpages);
4268 /* XXX This looks as if it should be newbsize > b_bufsize */
4269 else if (size > bp->b_bcount)
4270 vfs_vmio_extend(bp, desiredpages, size);
4271 bufspace_adjust(bp, newbsize);
4273 bp->b_bcount = size; /* requested buffer size. */
4277 extern int inflight_transient_maps;
4279 static struct bio_queue nondump_bios;
4282 biodone(struct bio *bp)
4285 void (*done)(struct bio *);
4286 vm_offset_t start, end;
4288 biotrack(bp, __func__);
4291 * Avoid completing I/O when dumping after a panic since that may
4292 * result in a deadlock in the filesystem or pager code. Note that
4293 * this doesn't affect dumps that were started manually since we aim
4294 * to keep the system usable after it has been resumed.
4296 if (__predict_false(dumping && SCHEDULER_STOPPED())) {
4297 TAILQ_INSERT_HEAD(&nondump_bios, bp, bio_queue);
4300 if ((bp->bio_flags & BIO_TRANSIENT_MAPPING) != 0) {
4301 bp->bio_flags &= ~BIO_TRANSIENT_MAPPING;
4302 bp->bio_flags |= BIO_UNMAPPED;
4303 start = trunc_page((vm_offset_t)bp->bio_data);
4304 end = round_page((vm_offset_t)bp->bio_data + bp->bio_length);
4305 bp->bio_data = unmapped_buf;
4306 pmap_qremove(start, atop(end - start));
4307 vmem_free(transient_arena, start, end - start);
4308 atomic_add_int(&inflight_transient_maps, -1);
4310 done = bp->bio_done;
4312 mtxp = mtx_pool_find(mtxpool_sleep, bp);
4314 bp->bio_flags |= BIO_DONE;
4322 * Wait for a BIO to finish.
4325 biowait(struct bio *bp, const char *wchan)
4329 mtxp = mtx_pool_find(mtxpool_sleep, bp);
4331 while ((bp->bio_flags & BIO_DONE) == 0)
4332 msleep(bp, mtxp, PRIBIO, wchan, 0);
4334 if (bp->bio_error != 0)
4335 return (bp->bio_error);
4336 if (!(bp->bio_flags & BIO_ERROR))
4342 biofinish(struct bio *bp, struct devstat *stat, int error)
4346 bp->bio_error = error;
4347 bp->bio_flags |= BIO_ERROR;
4350 devstat_end_transaction_bio(stat, bp);
4354 #if defined(BUF_TRACKING) || defined(FULL_BUF_TRACKING)
4356 biotrack_buf(struct bio *bp, const char *location)
4359 buf_track(bp->bio_track_bp, location);
4366 * Wait for buffer I/O completion, returning error status. The buffer
4367 * is left locked and B_DONE on return. B_EINTR is converted into an EINTR
4368 * error and cleared.
4371 bufwait(struct buf *bp)
4373 if (bp->b_iocmd == BIO_READ)
4374 bwait(bp, PRIBIO, "biord");
4376 bwait(bp, PRIBIO, "biowr");
4377 if (bp->b_flags & B_EINTR) {
4378 bp->b_flags &= ~B_EINTR;
4381 if (bp->b_ioflags & BIO_ERROR) {
4382 return (bp->b_error ? bp->b_error : EIO);
4391 * Finish I/O on a buffer, optionally calling a completion function.
4392 * This is usually called from an interrupt so process blocking is
4395 * biodone is also responsible for setting B_CACHE in a B_VMIO bp.
4396 * In a non-VMIO bp, B_CACHE will be set on the next getblk()
4397 * assuming B_INVAL is clear.
4399 * For the VMIO case, we set B_CACHE if the op was a read and no
4400 * read error occurred, or if the op was a write. B_CACHE is never
4401 * set if the buffer is invalid or otherwise uncacheable.
4403 * bufdone does not mess with B_INVAL, allowing the I/O routine or the
4404 * initiator to leave B_INVAL set to brelse the buffer out of existence
4405 * in the biodone routine.
4408 bufdone(struct buf *bp)
4410 struct bufobj *dropobj;
4411 void (*biodone)(struct buf *);
4413 buf_track(bp, __func__);
4414 CTR3(KTR_BUF, "bufdone(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
4417 KASSERT(!(bp->b_flags & B_DONE), ("biodone: bp %p already done", bp));
4419 runningbufwakeup(bp);
4420 if (bp->b_iocmd == BIO_WRITE)
4421 dropobj = bp->b_bufobj;
4422 /* call optional completion function if requested */
4423 if (bp->b_iodone != NULL) {
4424 biodone = bp->b_iodone;
4425 bp->b_iodone = NULL;
4428 bufobj_wdrop(dropobj);
4431 if (bp->b_flags & B_VMIO) {
4433 * Set B_CACHE if the op was a normal read and no error
4434 * occurred. B_CACHE is set for writes in the b*write()
4437 if (bp->b_iocmd == BIO_READ &&
4438 !(bp->b_flags & (B_INVAL|B_NOCACHE)) &&
4439 !(bp->b_ioflags & BIO_ERROR))
4440 bp->b_flags |= B_CACHE;
4441 vfs_vmio_iodone(bp);
4443 if (!LIST_EMPTY(&bp->b_dep))
4445 if ((bp->b_flags & B_CKHASH) != 0) {
4446 KASSERT(bp->b_iocmd == BIO_READ,
4447 ("bufdone: b_iocmd %d not BIO_READ", bp->b_iocmd));
4448 KASSERT(buf_mapped(bp), ("bufdone: bp %p not mapped", bp));
4449 (*bp->b_ckhashcalc)(bp);
4452 * For asynchronous completions, release the buffer now. The brelse
4453 * will do a wakeup there if necessary - so no need to do a wakeup
4454 * here in the async case. The sync case always needs to do a wakeup.
4456 if (bp->b_flags & B_ASYNC) {
4457 if ((bp->b_flags & (B_NOCACHE | B_INVAL | B_RELBUF)) ||
4458 (bp->b_ioflags & BIO_ERROR))
4465 bufobj_wdrop(dropobj);
4469 * This routine is called in lieu of iodone in the case of
4470 * incomplete I/O. This keeps the busy status for pages
4474 vfs_unbusy_pages(struct buf *bp)
4481 runningbufwakeup(bp);
4482 if (!(bp->b_flags & B_VMIO))
4485 obj = bp->b_bufobj->bo_object;
4487 for (i = 0; i < bp->b_npages; i++) {
4489 if (m == bogus_page) {
4490 if (bogus == false) {
4492 VM_OBJECT_RLOCK(obj);
4494 m = vm_page_lookup(obj, OFF_TO_IDX(bp->b_offset) + i);
4496 panic("vfs_unbusy_pages: page missing\n");
4498 if (buf_mapped(bp)) {
4499 BUF_CHECK_MAPPED(bp);
4500 pmap_qenter(trunc_page((vm_offset_t)bp->b_data),
4501 bp->b_pages, bp->b_npages);
4503 BUF_CHECK_UNMAPPED(bp);
4508 VM_OBJECT_RUNLOCK(obj);
4509 vm_object_pip_wakeupn(obj, bp->b_npages);
4513 * vfs_page_set_valid:
4515 * Set the valid bits in a page based on the supplied offset. The
4516 * range is restricted to the buffer's size.
4518 * This routine is typically called after a read completes.
4521 vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, vm_page_t m)
4526 * Compute the end offset, eoff, such that [off, eoff) does not span a
4527 * page boundary and eoff is not greater than the end of the buffer.
4528 * The end of the buffer, in this case, is our file EOF, not the
4529 * allocation size of the buffer.
4531 eoff = (off + PAGE_SIZE) & ~(vm_ooffset_t)PAGE_MASK;
4532 if (eoff > bp->b_offset + bp->b_bcount)
4533 eoff = bp->b_offset + bp->b_bcount;
4536 * Set valid range. This is typically the entire buffer and thus the
4540 vm_page_set_valid_range(m, off & PAGE_MASK, eoff - off);
4544 * vfs_page_set_validclean:
4546 * Set the valid bits and clear the dirty bits in a page based on the
4547 * supplied offset. The range is restricted to the buffer's size.
4550 vfs_page_set_validclean(struct buf *bp, vm_ooffset_t off, vm_page_t m)
4552 vm_ooffset_t soff, eoff;
4555 * Start and end offsets in buffer. eoff - soff may not cross a
4556 * page boundary or cross the end of the buffer. The end of the
4557 * buffer, in this case, is our file EOF, not the allocation size
4561 eoff = (off + PAGE_SIZE) & ~(off_t)PAGE_MASK;
4562 if (eoff > bp->b_offset + bp->b_bcount)
4563 eoff = bp->b_offset + bp->b_bcount;
4566 * Set valid range. This is typically the entire buffer and thus the
4570 vm_page_set_validclean(
4572 (vm_offset_t) (soff & PAGE_MASK),
4573 (vm_offset_t) (eoff - soff)
4579 * Acquire a shared busy on all pages in the buf.
4582 vfs_busy_pages_acquire(struct buf *bp)
4586 for (i = 0; i < bp->b_npages; i++)
4587 vm_page_busy_acquire(bp->b_pages[i], VM_ALLOC_SBUSY);
4591 vfs_busy_pages_release(struct buf *bp)
4595 for (i = 0; i < bp->b_npages; i++)
4596 vm_page_sunbusy(bp->b_pages[i]);
4600 * This routine is called before a device strategy routine.
4601 * It is used to tell the VM system that paging I/O is in
4602 * progress, and treat the pages associated with the buffer
4603 * almost as being exclusive busy. Also the object paging_in_progress
4604 * flag is handled to make sure that the object doesn't become
4607 * Since I/O has not been initiated yet, certain buffer flags
4608 * such as BIO_ERROR or B_INVAL may be in an inconsistent state
4609 * and should be ignored.
4612 vfs_busy_pages(struct buf *bp, int clear_modify)
4620 if (!(bp->b_flags & B_VMIO))
4623 obj = bp->b_bufobj->bo_object;
4624 foff = bp->b_offset;
4625 KASSERT(bp->b_offset != NOOFFSET,
4626 ("vfs_busy_pages: no buffer offset"));
4627 if ((bp->b_flags & B_CLUSTER) == 0) {
4628 vm_object_pip_add(obj, bp->b_npages);
4629 vfs_busy_pages_acquire(bp);
4631 if (bp->b_bufsize != 0)
4632 vfs_setdirty_range(bp);
4634 for (i = 0; i < bp->b_npages; i++) {
4636 vm_page_assert_sbusied(m);
4639 * When readying a buffer for a read ( i.e
4640 * clear_modify == 0 ), it is important to do
4641 * bogus_page replacement for valid pages in
4642 * partially instantiated buffers. Partially
4643 * instantiated buffers can, in turn, occur when
4644 * reconstituting a buffer from its VM backing store
4645 * base. We only have to do this if B_CACHE is
4646 * clear ( which causes the I/O to occur in the
4647 * first place ). The replacement prevents the read
4648 * I/O from overwriting potentially dirty VM-backed
4649 * pages. XXX bogus page replacement is, uh, bogus.
4650 * It may not work properly with small-block devices.
4651 * We need to find a better way.
4654 pmap_remove_write(m);
4655 vfs_page_set_validclean(bp, foff, m);
4656 } else if (vm_page_all_valid(m) &&
4657 (bp->b_flags & B_CACHE) == 0) {
4658 bp->b_pages[i] = bogus_page;
4661 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK;
4663 if (bogus && buf_mapped(bp)) {
4664 BUF_CHECK_MAPPED(bp);
4665 pmap_qenter(trunc_page((vm_offset_t)bp->b_data),
4666 bp->b_pages, bp->b_npages);
4671 * vfs_bio_set_valid:
4673 * Set the range within the buffer to valid. The range is
4674 * relative to the beginning of the buffer, b_offset. Note that
4675 * b_offset itself may be offset from the beginning of the first
4679 vfs_bio_set_valid(struct buf *bp, int base, int size)
4684 if (!(bp->b_flags & B_VMIO))
4688 * Fixup base to be relative to beginning of first page.
4689 * Set initial n to be the maximum number of bytes in the
4690 * first page that can be validated.
4692 base += (bp->b_offset & PAGE_MASK);
4693 n = PAGE_SIZE - (base & PAGE_MASK);
4696 * Busy may not be strictly necessary here because the pages are
4697 * unlikely to be fully valid and the vnode lock will synchronize
4698 * their access via getpages. It is grabbed for consistency with
4699 * other page validation.
4701 vfs_busy_pages_acquire(bp);
4702 for (i = base / PAGE_SIZE; size > 0 && i < bp->b_npages; ++i) {
4706 vm_page_set_valid_range(m, base & PAGE_MASK, n);
4711 vfs_busy_pages_release(bp);
4717 * If the specified buffer is a non-VMIO buffer, clear the entire
4718 * buffer. If the specified buffer is a VMIO buffer, clear and
4719 * validate only the previously invalid portions of the buffer.
4720 * This routine essentially fakes an I/O, so we need to clear
4721 * BIO_ERROR and B_INVAL.
4723 * Note that while we only theoretically need to clear through b_bcount,
4724 * we go ahead and clear through b_bufsize.
4727 vfs_bio_clrbuf(struct buf *bp)
4729 int i, j, mask, sa, ea, slide;
4731 if ((bp->b_flags & (B_VMIO | B_MALLOC)) != B_VMIO) {
4735 bp->b_flags &= ~B_INVAL;
4736 bp->b_ioflags &= ~BIO_ERROR;
4737 vfs_busy_pages_acquire(bp);
4738 sa = bp->b_offset & PAGE_MASK;
4740 for (i = 0; i < bp->b_npages; i++, sa = 0) {
4741 slide = imin(slide + PAGE_SIZE, bp->b_offset + bp->b_bufsize);
4742 ea = slide & PAGE_MASK;
4745 if (bp->b_pages[i] == bogus_page)
4748 mask = ((1 << ((ea - sa) / DEV_BSIZE)) - 1) << j;
4749 if ((bp->b_pages[i]->valid & mask) == mask)
4751 if ((bp->b_pages[i]->valid & mask) == 0)
4752 pmap_zero_page_area(bp->b_pages[i], sa, ea - sa);
4754 for (; sa < ea; sa += DEV_BSIZE, j++) {
4755 if ((bp->b_pages[i]->valid & (1 << j)) == 0) {
4756 pmap_zero_page_area(bp->b_pages[i],
4761 vm_page_set_valid_range(bp->b_pages[i], j * DEV_BSIZE,
4762 roundup2(ea - sa, DEV_BSIZE));
4764 vfs_busy_pages_release(bp);
4769 vfs_bio_bzero_buf(struct buf *bp, int base, int size)
4774 if (buf_mapped(bp)) {
4775 BUF_CHECK_MAPPED(bp);
4776 bzero(bp->b_data + base, size);
4778 BUF_CHECK_UNMAPPED(bp);
4779 n = PAGE_SIZE - (base & PAGE_MASK);
4780 for (i = base / PAGE_SIZE; size > 0 && i < bp->b_npages; ++i) {
4784 pmap_zero_page_area(m, base & PAGE_MASK, n);
4793 * Update buffer flags based on I/O request parameters, optionally releasing the
4794 * buffer. If it's VMIO or direct I/O, the buffer pages are released to the VM,
4795 * where they may be placed on a page queue (VMIO) or freed immediately (direct
4796 * I/O). Otherwise the buffer is released to the cache.
4799 b_io_dismiss(struct buf *bp, int ioflag, bool release)
4802 KASSERT((ioflag & IO_NOREUSE) == 0 || (ioflag & IO_VMIO) != 0,
4803 ("buf %p non-VMIO noreuse", bp));
4805 if ((ioflag & IO_DIRECT) != 0)
4806 bp->b_flags |= B_DIRECT;
4807 if ((ioflag & IO_EXT) != 0)
4808 bp->b_xflags |= BX_ALTDATA;
4809 if ((ioflag & (IO_VMIO | IO_DIRECT)) != 0 && LIST_EMPTY(&bp->b_dep)) {
4810 bp->b_flags |= B_RELBUF;
4811 if ((ioflag & IO_NOREUSE) != 0)
4812 bp->b_flags |= B_NOREUSE;
4820 vfs_bio_brelse(struct buf *bp, int ioflag)
4823 b_io_dismiss(bp, ioflag, true);
4827 vfs_bio_set_flags(struct buf *bp, int ioflag)
4830 b_io_dismiss(bp, ioflag, false);
4834 * vm_hold_load_pages and vm_hold_free_pages get pages into
4835 * a buffers address space. The pages are anonymous and are
4836 * not associated with a file object.
4839 vm_hold_load_pages(struct buf *bp, vm_offset_t from, vm_offset_t to)
4845 BUF_CHECK_MAPPED(bp);
4847 to = round_page(to);
4848 from = round_page(from);
4849 index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT;
4851 for (pg = from; pg < to; pg += PAGE_SIZE, index++) {
4853 * note: must allocate system pages since blocking here
4854 * could interfere with paging I/O, no matter which
4857 p = vm_page_alloc(NULL, 0, VM_ALLOC_SYSTEM | VM_ALLOC_NOOBJ |
4858 VM_ALLOC_WIRED | VM_ALLOC_COUNT((to - pg) >> PAGE_SHIFT) |
4860 pmap_qenter(pg, &p, 1);
4861 bp->b_pages[index] = p;
4863 bp->b_npages = index;
4866 /* Return pages associated with this buf to the vm system */
4868 vm_hold_free_pages(struct buf *bp, int newbsize)
4872 int index, newnpages;
4874 BUF_CHECK_MAPPED(bp);
4876 from = round_page((vm_offset_t)bp->b_data + newbsize);
4877 newnpages = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT;
4878 if (bp->b_npages > newnpages)
4879 pmap_qremove(from, bp->b_npages - newnpages);
4880 for (index = newnpages; index < bp->b_npages; index++) {
4881 p = bp->b_pages[index];
4882 bp->b_pages[index] = NULL;
4883 vm_page_unwire_noq(p);
4886 bp->b_npages = newnpages;
4890 * Map an IO request into kernel virtual address space.
4892 * All requests are (re)mapped into kernel VA space.
4893 * Notice that we use b_bufsize for the size of the buffer
4894 * to be mapped. b_bcount might be modified by the driver.
4896 * Note that even if the caller determines that the address space should
4897 * be valid, a race or a smaller-file mapped into a larger space may
4898 * actually cause vmapbuf() to fail, so all callers of vmapbuf() MUST
4899 * check the return value.
4901 * This function only works with pager buffers.
4904 vmapbuf(struct buf *bp, int mapbuf)
4909 if (bp->b_bufsize < 0)
4911 prot = VM_PROT_READ;
4912 if (bp->b_iocmd == BIO_READ)
4913 prot |= VM_PROT_WRITE; /* Less backwards than it looks */
4914 if ((pidx = vm_fault_quick_hold_pages(&curproc->p_vmspace->vm_map,
4915 (vm_offset_t)bp->b_data, bp->b_bufsize, prot, bp->b_pages,
4916 btoc(MAXPHYS))) < 0)
4918 bp->b_npages = pidx;
4919 bp->b_offset = ((vm_offset_t)bp->b_data) & PAGE_MASK;
4920 if (mapbuf || !unmapped_buf_allowed) {
4921 pmap_qenter((vm_offset_t)bp->b_kvabase, bp->b_pages, pidx);
4922 bp->b_data = bp->b_kvabase + bp->b_offset;
4924 bp->b_data = unmapped_buf;
4929 * Free the io map PTEs associated with this IO operation.
4930 * We also invalidate the TLB entries and restore the original b_addr.
4932 * This function only works with pager buffers.
4935 vunmapbuf(struct buf *bp)
4939 npages = bp->b_npages;
4941 pmap_qremove(trunc_page((vm_offset_t)bp->b_data), npages);
4942 vm_page_unhold_pages(bp->b_pages, npages);
4944 bp->b_data = unmapped_buf;
4948 bdone(struct buf *bp)
4952 mtxp = mtx_pool_find(mtxpool_sleep, bp);
4954 bp->b_flags |= B_DONE;
4960 bwait(struct buf *bp, u_char pri, const char *wchan)
4964 mtxp = mtx_pool_find(mtxpool_sleep, bp);
4966 while ((bp->b_flags & B_DONE) == 0)
4967 msleep(bp, mtxp, pri, wchan, 0);
4972 bufsync(struct bufobj *bo, int waitfor)
4975 return (VOP_FSYNC(bo2vnode(bo), waitfor, curthread));
4979 bufstrategy(struct bufobj *bo, struct buf *bp)
4985 KASSERT(vp == bo->bo_private, ("Inconsistent vnode bufstrategy"));
4986 KASSERT(vp->v_type != VCHR && vp->v_type != VBLK,
4987 ("Wrong vnode in bufstrategy(bp=%p, vp=%p)", bp, vp));
4988 i = VOP_STRATEGY(vp, bp);
4989 KASSERT(i == 0, ("VOP_STRATEGY failed bp=%p vp=%p", bp, bp->b_vp));
4993 * Initialize a struct bufobj before use. Memory is assumed zero filled.
4996 bufobj_init(struct bufobj *bo, void *private)
4998 static volatile int bufobj_cleanq;
5001 atomic_fetchadd_int(&bufobj_cleanq, 1) % buf_domains;
5002 rw_init(BO_LOCKPTR(bo), "bufobj interlock");
5003 bo->bo_private = private;
5004 TAILQ_INIT(&bo->bo_clean.bv_hd);
5005 TAILQ_INIT(&bo->bo_dirty.bv_hd);
5009 bufobj_wrefl(struct bufobj *bo)
5012 KASSERT(bo != NULL, ("NULL bo in bufobj_wref"));
5013 ASSERT_BO_WLOCKED(bo);
5018 bufobj_wref(struct bufobj *bo)
5021 KASSERT(bo != NULL, ("NULL bo in bufobj_wref"));
5028 bufobj_wdrop(struct bufobj *bo)
5031 KASSERT(bo != NULL, ("NULL bo in bufobj_wdrop"));
5033 KASSERT(bo->bo_numoutput > 0, ("bufobj_wdrop non-positive count"));
5034 if ((--bo->bo_numoutput == 0) && (bo->bo_flag & BO_WWAIT)) {
5035 bo->bo_flag &= ~BO_WWAIT;
5036 wakeup(&bo->bo_numoutput);
5042 bufobj_wwait(struct bufobj *bo, int slpflag, int timeo)
5046 KASSERT(bo != NULL, ("NULL bo in bufobj_wwait"));
5047 ASSERT_BO_WLOCKED(bo);
5049 while (bo->bo_numoutput) {
5050 bo->bo_flag |= BO_WWAIT;
5051 error = msleep(&bo->bo_numoutput, BO_LOCKPTR(bo),
5052 slpflag | (PRIBIO + 1), "bo_wwait", timeo);
5060 * Set bio_data or bio_ma for struct bio from the struct buf.
5063 bdata2bio(struct buf *bp, struct bio *bip)
5066 if (!buf_mapped(bp)) {
5067 KASSERT(unmapped_buf_allowed, ("unmapped"));
5068 bip->bio_ma = bp->b_pages;
5069 bip->bio_ma_n = bp->b_npages;
5070 bip->bio_data = unmapped_buf;
5071 bip->bio_ma_offset = (vm_offset_t)bp->b_offset & PAGE_MASK;
5072 bip->bio_flags |= BIO_UNMAPPED;
5073 KASSERT(round_page(bip->bio_ma_offset + bip->bio_length) /
5074 PAGE_SIZE == bp->b_npages,
5075 ("Buffer %p too short: %d %lld %d", bp, bip->bio_ma_offset,
5076 (long long)bip->bio_length, bip->bio_ma_n));
5078 bip->bio_data = bp->b_data;
5084 * The MIPS pmap code currently doesn't handle aliased pages.
5085 * The VIPT caches may not handle page aliasing themselves, leading
5086 * to data corruption.
5088 * As such, this code makes a system extremely unhappy if said
5089 * system doesn't support unaliasing the above situation in hardware.
5090 * Some "recent" systems (eg some mips24k/mips74k cores) don't enable
5091 * this feature at build time, so it has to be handled in software.
5093 * Once the MIPS pmap/cache code grows to support this function on
5094 * earlier chips, it should be flipped back off.
5097 static int buf_pager_relbuf = 1;
5099 static int buf_pager_relbuf = 0;
5101 SYSCTL_INT(_vfs, OID_AUTO, buf_pager_relbuf, CTLFLAG_RWTUN,
5102 &buf_pager_relbuf, 0,
5103 "Make buffer pager release buffers after reading");
5106 * The buffer pager. It uses buffer reads to validate pages.
5108 * In contrast to the generic local pager from vm/vnode_pager.c, this
5109 * pager correctly and easily handles volumes where the underlying
5110 * device block size is greater than the machine page size. The
5111 * buffer cache transparently extends the requested page run to be
5112 * aligned at the block boundary, and does the necessary bogus page
5113 * replacements in the addends to avoid obliterating already valid
5116 * The only non-trivial issue is that the exclusive busy state for
5117 * pages, which is assumed by the vm_pager_getpages() interface, is
5118 * incompatible with the VMIO buffer cache's desire to share-busy the
5119 * pages. This function performs a trivial downgrade of the pages'
5120 * state before reading buffers, and a less trivial upgrade from the
5121 * shared-busy to excl-busy state after the read.
5124 vfs_bio_getpages(struct vnode *vp, vm_page_t *ma, int count,
5125 int *rbehind, int *rahead, vbg_get_lblkno_t get_lblkno,
5126 vbg_get_blksize_t get_blksize)
5133 vm_ooffset_t la, lb, poff, poffe;
5135 int bo_bs, br_flags, error, i, pgsin, pgsin_a, pgsin_b;
5138 object = vp->v_object;
5141 la = IDX_TO_OFF(ma[count - 1]->pindex);
5142 if (la >= object->un_pager.vnp.vnp_size)
5143 return (VM_PAGER_BAD);
5146 * Change the meaning of la from where the last requested page starts
5147 * to where it ends, because that's the end of the requested region
5148 * and the start of the potential read-ahead region.
5151 lpart = la > object->un_pager.vnp.vnp_size;
5152 bo_bs = get_blksize(vp, get_lblkno(vp, IDX_TO_OFF(ma[0]->pindex)));
5155 * Calculate read-ahead, behind and total pages.
5158 lb = IDX_TO_OFF(ma[0]->pindex);
5159 pgsin_b = OFF_TO_IDX(lb - rounddown2(lb, bo_bs));
5161 if (rbehind != NULL)
5163 pgsin_a = OFF_TO_IDX(roundup2(la, bo_bs) - la);
5164 if (la + IDX_TO_OFF(pgsin_a) >= object->un_pager.vnp.vnp_size)
5165 pgsin_a = OFF_TO_IDX(roundup2(object->un_pager.vnp.vnp_size,
5170 VM_CNT_INC(v_vnodein);
5171 VM_CNT_ADD(v_vnodepgsin, pgsin);
5173 br_flags = (mp != NULL && (mp->mnt_kern_flag & MNTK_UNMAPPED_BUFS)
5174 != 0) ? GB_UNMAPPED : 0;
5176 for (i = 0; i < count; i++)
5177 vm_page_busy_downgrade(ma[i]);
5180 for (i = 0; i < count; i++) {
5184 * Pages are shared busy and the object lock is not
5185 * owned, which together allow for the pages'
5186 * invalidation. The racy test for validity avoids
5187 * useless creation of the buffer for the most typical
5188 * case when invalidation is not used in redo or for
5189 * parallel read. The shared->excl upgrade loop at
5190 * the end of the function catches the race in a
5191 * reliable way (protected by the object lock).
5193 if (vm_page_all_valid(m))
5196 poff = IDX_TO_OFF(m->pindex);
5197 poffe = MIN(poff + PAGE_SIZE, object->un_pager.vnp.vnp_size);
5198 for (; poff < poffe; poff += bsize) {
5199 lbn = get_lblkno(vp, poff);
5204 bsize = get_blksize(vp, lbn);
5205 error = bread_gb(vp, lbn, bsize, curthread->td_ucred,
5209 if (LIST_EMPTY(&bp->b_dep)) {
5211 * Invalidation clears m->valid, but
5212 * may leave B_CACHE flag if the
5213 * buffer existed at the invalidation
5214 * time. In this case, recycle the
5215 * buffer to do real read on next
5216 * bread() after redo.
5218 * Otherwise B_RELBUF is not strictly
5219 * necessary, enable to reduce buf
5222 if (buf_pager_relbuf ||
5223 !vm_page_all_valid(m))
5224 bp->b_flags |= B_RELBUF;
5226 bp->b_flags &= ~B_NOCACHE;
5232 KASSERT(1 /* racy, enable for debugging */ ||
5233 vm_page_all_valid(m) || i == count - 1,
5234 ("buf %d %p invalid", i, m));
5235 if (i == count - 1 && lpart) {
5236 if (!vm_page_none_valid(m) &&
5237 !vm_page_all_valid(m))
5238 vm_page_zero_invalid(m, TRUE);
5244 VM_OBJECT_WLOCK(object);
5246 for (i = 0; i < count; i++) {
5247 vm_page_sunbusy(ma[i]);
5248 ma[i] = vm_page_grab(object, ma[i]->pindex, VM_ALLOC_NORMAL);
5251 * Since the pages were only sbusy while neither the
5252 * buffer nor the object lock was held by us, or
5253 * reallocated while vm_page_grab() slept for busy
5254 * relinguish, they could have been invalidated.
5255 * Recheck the valid bits and re-read as needed.
5257 * Note that the last page is made fully valid in the
5258 * read loop, and partial validity for the page at
5259 * index count - 1 could mean that the page was
5260 * invalidated or removed, so we must restart for
5263 if (!vm_page_all_valid(ma[i]))
5266 VM_OBJECT_WUNLOCK(object);
5267 if (redo && error == 0)
5269 return (error != 0 ? VM_PAGER_ERROR : VM_PAGER_OK);
5272 #include "opt_ddb.h"
5274 #include <ddb/ddb.h>
5276 /* DDB command to show buffer data */
5277 DB_SHOW_COMMAND(buffer, db_show_buffer)
5280 struct buf *bp = (struct buf *)addr;
5281 #ifdef FULL_BUF_TRACKING
5286 db_printf("usage: show buffer <addr>\n");
5290 db_printf("buf at %p\n", bp);
5291 db_printf("b_flags = 0x%b, b_xflags=0x%b\n",
5292 (u_int)bp->b_flags, PRINT_BUF_FLAGS,
5293 (u_int)bp->b_xflags, PRINT_BUF_XFLAGS);
5294 db_printf("b_vflags=0x%b b_ioflags0x%b\n",
5295 (u_int)bp->b_vflags, PRINT_BUF_VFLAGS,
5296 (u_int)bp->b_ioflags, PRINT_BIO_FLAGS);
5298 "b_error = %d, b_bufsize = %ld, b_bcount = %ld, b_resid = %ld\n"
5299 "b_bufobj = (%p), b_data = %p\n, b_blkno = %jd, b_lblkno = %jd, "
5300 "b_vp = %p, b_dep = %p\n",
5301 bp->b_error, bp->b_bufsize, bp->b_bcount, bp->b_resid,
5302 bp->b_bufobj, bp->b_data, (intmax_t)bp->b_blkno,
5303 (intmax_t)bp->b_lblkno, bp->b_vp, bp->b_dep.lh_first);
5304 db_printf("b_kvabase = %p, b_kvasize = %d\n",
5305 bp->b_kvabase, bp->b_kvasize);
5308 db_printf("b_npages = %d, pages(OBJ, IDX, PA): ", bp->b_npages);
5309 for (i = 0; i < bp->b_npages; i++) {
5313 db_printf("(%p, 0x%lx, 0x%lx)", m->object,
5315 (u_long)VM_PAGE_TO_PHYS(m));
5317 db_printf("( ??? )");
5318 if ((i + 1) < bp->b_npages)
5323 BUF_LOCKPRINTINFO(bp);
5324 #if defined(FULL_BUF_TRACKING)
5325 db_printf("b_io_tracking: b_io_tcnt = %u\n", bp->b_io_tcnt);
5327 i = bp->b_io_tcnt % BUF_TRACKING_SIZE;
5328 for (j = 1; j <= BUF_TRACKING_SIZE; j++) {
5329 if (bp->b_io_tracking[BUF_TRACKING_ENTRY(i - j)] == NULL)
5331 db_printf(" %2u: %s\n", j,
5332 bp->b_io_tracking[BUF_TRACKING_ENTRY(i - j)]);
5334 #elif defined(BUF_TRACKING)
5335 db_printf("b_io_tracking: %s\n", bp->b_io_tracking);
5340 DB_SHOW_COMMAND(bufqueues, bufqueues)
5342 struct bufdomain *bd;
5347 db_printf("bqempty: %d\n", bqempty.bq_len);
5349 for (i = 0; i < buf_domains; i++) {
5351 db_printf("Buf domain %d\n", i);
5352 db_printf("\tfreebufs\t%d\n", bd->bd_freebuffers);
5353 db_printf("\tlofreebufs\t%d\n", bd->bd_lofreebuffers);
5354 db_printf("\thifreebufs\t%d\n", bd->bd_hifreebuffers);
5356 db_printf("\tbufspace\t%ld\n", bd->bd_bufspace);
5357 db_printf("\tmaxbufspace\t%ld\n", bd->bd_maxbufspace);
5358 db_printf("\thibufspace\t%ld\n", bd->bd_hibufspace);
5359 db_printf("\tlobufspace\t%ld\n", bd->bd_lobufspace);
5360 db_printf("\tbufspacethresh\t%ld\n", bd->bd_bufspacethresh);
5362 db_printf("\tnumdirtybuffers\t%d\n", bd->bd_numdirtybuffers);
5363 db_printf("\tlodirtybuffers\t%d\n", bd->bd_lodirtybuffers);
5364 db_printf("\thidirtybuffers\t%d\n", bd->bd_hidirtybuffers);
5365 db_printf("\tdirtybufthresh\t%d\n", bd->bd_dirtybufthresh);
5368 TAILQ_FOREACH(bp, &bd->bd_cleanq->bq_queue, b_freelist)
5369 total += bp->b_bufsize;
5370 db_printf("\tcleanq count\t%d (%ld)\n",
5371 bd->bd_cleanq->bq_len, total);
5373 TAILQ_FOREACH(bp, &bd->bd_dirtyq.bq_queue, b_freelist)
5374 total += bp->b_bufsize;
5375 db_printf("\tdirtyq count\t%d (%ld)\n",
5376 bd->bd_dirtyq.bq_len, total);
5377 db_printf("\twakeup\t\t%d\n", bd->bd_wanted);
5378 db_printf("\tlim\t\t%d\n", bd->bd_lim);
5379 db_printf("\tCPU ");
5380 for (j = 0; j <= mp_maxid; j++)
5381 db_printf("%d, ", bd->bd_subq[j].bq_len);
5385 for (j = 0; j < nbuf; j++)
5386 if (buf[j].b_domain == i && BUF_ISLOCKED(&buf[j])) {
5388 total += buf[j].b_bufsize;
5390 db_printf("\tLocked buffers: %d space %ld\n", cnt, total);
5393 for (j = 0; j < nbuf; j++)
5394 if (buf[j].b_domain == i) {
5396 total += buf[j].b_bufsize;
5398 db_printf("\tTotal buffers: %d space %ld\n", cnt, total);
5402 DB_SHOW_COMMAND(lockedbufs, lockedbufs)
5407 for (i = 0; i < nbuf; i++) {
5409 if (BUF_ISLOCKED(bp)) {
5410 db_show_buffer((uintptr_t)bp, 1, 0, NULL);
5418 DB_SHOW_COMMAND(vnodebufs, db_show_vnodebufs)
5424 db_printf("usage: show vnodebufs <addr>\n");
5427 vp = (struct vnode *)addr;
5428 db_printf("Clean buffers:\n");
5429 TAILQ_FOREACH(bp, &vp->v_bufobj.bo_clean.bv_hd, b_bobufs) {
5430 db_show_buffer((uintptr_t)bp, 1, 0, NULL);
5433 db_printf("Dirty buffers:\n");
5434 TAILQ_FOREACH(bp, &vp->v_bufobj.bo_dirty.bv_hd, b_bobufs) {
5435 db_show_buffer((uintptr_t)bp, 1, 0, NULL);
5440 DB_COMMAND(countfreebufs, db_coundfreebufs)
5443 int i, used = 0, nfree = 0;
5446 db_printf("usage: countfreebufs\n");
5450 for (i = 0; i < nbuf; i++) {
5452 if (bp->b_qindex == QUEUE_EMPTY)
5458 db_printf("Counted %d free, %d used (%d tot)\n", nfree, used,
5460 db_printf("numfreebuffers is %d\n", numfreebuffers);