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);
1386 mi_switch(SW_VOL, NULL);
1387 thread_unlock(curthread);
1394 * Count only busy local buffers to prevent forcing
1395 * a fsck if we're just a client of a wedged NFS server
1398 for (bp = &buf[nbuf]; --bp >= buf; ) {
1399 if (isbufbusy(bp)) {
1401 /* XXX: This is bogus. We should probably have a BO_REMOTE flag instead */
1402 if (bp->b_dev == NULL) {
1403 TAILQ_REMOVE(&mountlist,
1404 bp->b_vp->v_mount, mnt_list);
1409 if (show_busybufs > 0) {
1411 "%d: buf:%p, vnode:%p, flags:%0x, blkno:%jd, lblkno:%jd, buflock:",
1412 nbusy, bp, bp->b_vp, bp->b_flags,
1413 (intmax_t)bp->b_blkno,
1414 (intmax_t)bp->b_lblkno);
1415 BUF_LOCKPRINTINFO(bp);
1416 if (show_busybufs > 1)
1424 * Failed to sync all blocks. Indicate this and don't
1425 * unmount filesystems (thus forcing an fsck on reboot).
1427 printf("Giving up on %d buffers\n", nbusy);
1428 DELAY(5000000); /* 5 seconds */
1430 if (!first_buf_printf)
1431 printf("Final sync complete\n");
1433 * Unmount filesystems
1435 if (panicstr == NULL)
1439 DELAY(100000); /* wait for console output to finish */
1443 bpmap_qenter(struct buf *bp)
1446 BUF_CHECK_MAPPED(bp);
1449 * bp->b_data is relative to bp->b_offset, but
1450 * bp->b_offset may be offset into the first page.
1452 bp->b_data = (caddr_t)trunc_page((vm_offset_t)bp->b_data);
1453 pmap_qenter((vm_offset_t)bp->b_data, bp->b_pages, bp->b_npages);
1454 bp->b_data = (caddr_t)((vm_offset_t)bp->b_data |
1455 (vm_offset_t)(bp->b_offset & PAGE_MASK));
1458 static inline struct bufdomain *
1459 bufdomain(struct buf *bp)
1462 return (&bdomain[bp->b_domain]);
1465 static struct bufqueue *
1466 bufqueue(struct buf *bp)
1469 switch (bp->b_qindex) {
1472 case QUEUE_SENTINEL:
1477 return (&bufdomain(bp)->bd_dirtyq);
1479 return (&bufdomain(bp)->bd_subq[bp->b_subqueue]);
1483 panic("bufqueue(%p): Unhandled type %d\n", bp, bp->b_qindex);
1487 * Return the locked bufqueue that bp is a member of.
1489 static struct bufqueue *
1490 bufqueue_acquire(struct buf *bp)
1492 struct bufqueue *bq, *nbq;
1495 * bp can be pushed from a per-cpu queue to the
1496 * cleanq while we're waiting on the lock. Retry
1497 * if the queues don't match.
1515 * Insert the buffer into the appropriate free list. Requires a
1516 * locked buffer on entry and buffer is unlocked before return.
1519 binsfree(struct buf *bp, int qindex)
1521 struct bufdomain *bd;
1522 struct bufqueue *bq;
1524 KASSERT(qindex == QUEUE_CLEAN || qindex == QUEUE_DIRTY,
1525 ("binsfree: Invalid qindex %d", qindex));
1526 BUF_ASSERT_XLOCKED(bp);
1529 * Handle delayed bremfree() processing.
1531 if (bp->b_flags & B_REMFREE) {
1532 if (bp->b_qindex == qindex) {
1533 bp->b_flags |= B_REUSE;
1534 bp->b_flags &= ~B_REMFREE;
1538 bq = bufqueue_acquire(bp);
1543 if (qindex == QUEUE_CLEAN) {
1544 if (bd->bd_lim != 0)
1545 bq = &bd->bd_subq[PCPU_GET(cpuid)];
1549 bq = &bd->bd_dirtyq;
1550 bq_insert(bq, bp, true);
1556 * Free a buffer to the buf zone once it no longer has valid contents.
1559 buf_free(struct buf *bp)
1562 if (bp->b_flags & B_REMFREE)
1564 if (bp->b_vflags & BV_BKGRDINPROG)
1565 panic("losing buffer 1");
1566 if (bp->b_rcred != NOCRED) {
1567 crfree(bp->b_rcred);
1568 bp->b_rcred = NOCRED;
1570 if (bp->b_wcred != NOCRED) {
1571 crfree(bp->b_wcred);
1572 bp->b_wcred = NOCRED;
1574 if (!LIST_EMPTY(&bp->b_dep))
1577 atomic_add_int(&bufdomain(bp)->bd_freebuffers, 1);
1579 uma_zfree(buf_zone, bp);
1585 * Import bufs into the uma cache from the buf list. The system still
1586 * expects a static array of bufs and much of the synchronization
1587 * around bufs assumes type stable storage. As a result, UMA is used
1588 * only as a per-cpu cache of bufs still maintained on a global list.
1591 buf_import(void *arg, void **store, int cnt, int domain, int flags)
1597 for (i = 0; i < cnt; i++) {
1598 bp = TAILQ_FIRST(&bqempty.bq_queue);
1601 bq_remove(&bqempty, bp);
1604 BQ_UNLOCK(&bqempty);
1612 * Release bufs from the uma cache back to the buffer queues.
1615 buf_release(void *arg, void **store, int cnt)
1617 struct bufqueue *bq;
1623 for (i = 0; i < cnt; i++) {
1625 /* Inline bq_insert() to batch locking. */
1626 TAILQ_INSERT_TAIL(&bq->bq_queue, bp, b_freelist);
1627 bp->b_flags &= ~(B_AGE | B_REUSE);
1629 bp->b_qindex = bq->bq_index;
1637 * Allocate an empty buffer header.
1640 buf_alloc(struct bufdomain *bd)
1646 * We can only run out of bufs in the buf zone if the average buf
1647 * is less than BKVASIZE. In this case the actual wait/block will
1648 * come from buf_reycle() failing to flush one of these small bufs.
1651 freebufs = atomic_fetchadd_int(&bd->bd_freebuffers, -1);
1653 bp = uma_zalloc(buf_zone, M_NOWAIT);
1655 atomic_add_int(&bd->bd_freebuffers, 1);
1656 bufspace_daemon_wakeup(bd);
1657 counter_u64_add(numbufallocfails, 1);
1661 * Wake-up the bufspace daemon on transition below threshold.
1663 if (freebufs == bd->bd_lofreebuffers)
1664 bufspace_daemon_wakeup(bd);
1666 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0)
1667 panic("getnewbuf_empty: Locked buf %p on free queue.", bp);
1669 KASSERT(bp->b_vp == NULL,
1670 ("bp: %p still has vnode %p.", bp, bp->b_vp));
1671 KASSERT((bp->b_flags & (B_DELWRI | B_NOREUSE)) == 0,
1672 ("invalid buffer %p flags %#x", bp, bp->b_flags));
1673 KASSERT((bp->b_xflags & (BX_VNCLEAN|BX_VNDIRTY)) == 0,
1674 ("bp: %p still on a buffer list. xflags %X", bp, bp->b_xflags));
1675 KASSERT(bp->b_npages == 0,
1676 ("bp: %p still has %d vm pages\n", bp, bp->b_npages));
1677 KASSERT(bp->b_kvasize == 0, ("bp: %p still has kva\n", bp));
1678 KASSERT(bp->b_bufsize == 0, ("bp: %p still has bufspace\n", bp));
1680 bp->b_domain = BD_DOMAIN(bd);
1686 bp->b_blkno = bp->b_lblkno = 0;
1687 bp->b_offset = NOOFFSET;
1693 bp->b_dirtyoff = bp->b_dirtyend = 0;
1694 bp->b_bufobj = NULL;
1695 bp->b_data = bp->b_kvabase = unmapped_buf;
1696 bp->b_fsprivate1 = NULL;
1697 bp->b_fsprivate2 = NULL;
1698 bp->b_fsprivate3 = NULL;
1699 LIST_INIT(&bp->b_dep);
1707 * Free a buffer from the given bufqueue. kva controls whether the
1708 * freed buf must own some kva resources. This is used for
1712 buf_recycle(struct bufdomain *bd, bool kva)
1714 struct bufqueue *bq;
1715 struct buf *bp, *nbp;
1718 counter_u64_add(bufdefragcnt, 1);
1722 KASSERT(BQ_LOCKPTR(bq) == BD_LOCKPTR(bd),
1723 ("buf_recycle: Locks don't match"));
1724 nbp = TAILQ_FIRST(&bq->bq_queue);
1727 * Run scan, possibly freeing data and/or kva mappings on the fly
1730 while ((bp = nbp) != NULL) {
1732 * Calculate next bp (we can only use it if we do not
1733 * release the bqlock).
1735 nbp = TAILQ_NEXT(bp, b_freelist);
1738 * If we are defragging then we need a buffer with
1739 * some kva to reclaim.
1741 if (kva && bp->b_kvasize == 0)
1744 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0)
1748 * Implement a second chance algorithm for frequently
1751 if ((bp->b_flags & B_REUSE) != 0) {
1752 TAILQ_REMOVE(&bq->bq_queue, bp, b_freelist);
1753 TAILQ_INSERT_TAIL(&bq->bq_queue, bp, b_freelist);
1754 bp->b_flags &= ~B_REUSE;
1760 * Skip buffers with background writes in progress.
1762 if ((bp->b_vflags & BV_BKGRDINPROG) != 0) {
1767 KASSERT(bp->b_qindex == QUEUE_CLEAN,
1768 ("buf_recycle: inconsistent queue %d bp %p",
1770 KASSERT(bp->b_domain == BD_DOMAIN(bd),
1771 ("getnewbuf: queue domain %d doesn't match request %d",
1772 bp->b_domain, (int)BD_DOMAIN(bd)));
1774 * NOTE: nbp is now entirely invalid. We can only restart
1775 * the scan from this point on.
1781 * Requeue the background write buffer with error and
1784 if ((bp->b_vflags & BV_BKGRDERR) != 0) {
1787 nbp = TAILQ_FIRST(&bq->bq_queue);
1790 bp->b_flags |= B_INVAL;
1803 * Mark the buffer for removal from the appropriate free list.
1807 bremfree(struct buf *bp)
1810 CTR3(KTR_BUF, "bremfree(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
1811 KASSERT((bp->b_flags & B_REMFREE) == 0,
1812 ("bremfree: buffer %p already marked for delayed removal.", bp));
1813 KASSERT(bp->b_qindex != QUEUE_NONE,
1814 ("bremfree: buffer %p not on a queue.", bp));
1815 BUF_ASSERT_XLOCKED(bp);
1817 bp->b_flags |= B_REMFREE;
1823 * Force an immediate removal from a free list. Used only in nfs when
1824 * it abuses the b_freelist pointer.
1827 bremfreef(struct buf *bp)
1829 struct bufqueue *bq;
1831 bq = bufqueue_acquire(bp);
1837 bq_init(struct bufqueue *bq, int qindex, int subqueue, const char *lockname)
1840 mtx_init(&bq->bq_lock, lockname, NULL, MTX_DEF);
1841 TAILQ_INIT(&bq->bq_queue);
1843 bq->bq_index = qindex;
1844 bq->bq_subqueue = subqueue;
1848 bd_init(struct bufdomain *bd)
1852 bd->bd_cleanq = &bd->bd_subq[mp_maxid + 1];
1853 bq_init(bd->bd_cleanq, QUEUE_CLEAN, mp_maxid + 1, "bufq clean lock");
1854 bq_init(&bd->bd_dirtyq, QUEUE_DIRTY, -1, "bufq dirty lock");
1855 for (i = 0; i <= mp_maxid; i++)
1856 bq_init(&bd->bd_subq[i], QUEUE_CLEAN, i,
1857 "bufq clean subqueue lock");
1858 mtx_init(&bd->bd_run_lock, "bufspace daemon run lock", NULL, MTX_DEF);
1864 * Removes a buffer from the free list, must be called with the
1865 * correct qlock held.
1868 bq_remove(struct bufqueue *bq, struct buf *bp)
1871 CTR3(KTR_BUF, "bq_remove(%p) vp %p flags %X",
1872 bp, bp->b_vp, bp->b_flags);
1873 KASSERT(bp->b_qindex != QUEUE_NONE,
1874 ("bq_remove: buffer %p not on a queue.", bp));
1875 KASSERT(bufqueue(bp) == bq,
1876 ("bq_remove: Remove buffer %p from wrong queue.", bp));
1878 BQ_ASSERT_LOCKED(bq);
1879 if (bp->b_qindex != QUEUE_EMPTY) {
1880 BUF_ASSERT_XLOCKED(bp);
1882 KASSERT(bq->bq_len >= 1,
1883 ("queue %d underflow", bp->b_qindex));
1884 TAILQ_REMOVE(&bq->bq_queue, bp, b_freelist);
1886 bp->b_qindex = QUEUE_NONE;
1887 bp->b_flags &= ~(B_REMFREE | B_REUSE);
1891 bd_flush(struct bufdomain *bd, struct bufqueue *bq)
1895 BQ_ASSERT_LOCKED(bq);
1896 if (bq != bd->bd_cleanq) {
1898 while ((bp = TAILQ_FIRST(&bq->bq_queue)) != NULL) {
1899 TAILQ_REMOVE(&bq->bq_queue, bp, b_freelist);
1900 TAILQ_INSERT_TAIL(&bd->bd_cleanq->bq_queue, bp,
1902 bp->b_subqueue = bd->bd_cleanq->bq_subqueue;
1904 bd->bd_cleanq->bq_len += bq->bq_len;
1907 if (bd->bd_wanted) {
1909 wakeup(&bd->bd_wanted);
1911 if (bq != bd->bd_cleanq)
1916 bd_flushall(struct bufdomain *bd)
1918 struct bufqueue *bq;
1922 if (bd->bd_lim == 0)
1925 for (i = 0; i <= mp_maxid; i++) {
1926 bq = &bd->bd_subq[i];
1927 if (bq->bq_len == 0)
1939 bq_insert(struct bufqueue *bq, struct buf *bp, bool unlock)
1941 struct bufdomain *bd;
1943 if (bp->b_qindex != QUEUE_NONE)
1944 panic("bq_insert: free buffer %p onto another queue?", bp);
1947 if (bp->b_flags & B_AGE) {
1948 /* Place this buf directly on the real queue. */
1949 if (bq->bq_index == QUEUE_CLEAN)
1952 TAILQ_INSERT_HEAD(&bq->bq_queue, bp, b_freelist);
1955 TAILQ_INSERT_TAIL(&bq->bq_queue, bp, b_freelist);
1957 bp->b_flags &= ~(B_AGE | B_REUSE);
1959 bp->b_qindex = bq->bq_index;
1960 bp->b_subqueue = bq->bq_subqueue;
1963 * Unlock before we notify so that we don't wakeup a waiter that
1964 * fails a trylock on the buf and sleeps again.
1969 if (bp->b_qindex == QUEUE_CLEAN) {
1971 * Flush the per-cpu queue and notify any waiters.
1973 if (bd->bd_wanted || (bq != bd->bd_cleanq &&
1974 bq->bq_len >= bd->bd_lim))
1983 * Free the kva allocation for a buffer.
1987 bufkva_free(struct buf *bp)
1991 if (bp->b_kvasize == 0) {
1992 KASSERT(bp->b_kvabase == unmapped_buf &&
1993 bp->b_data == unmapped_buf,
1994 ("Leaked KVA space on %p", bp));
1995 } else if (buf_mapped(bp))
1996 BUF_CHECK_MAPPED(bp);
1998 BUF_CHECK_UNMAPPED(bp);
2000 if (bp->b_kvasize == 0)
2003 vmem_free(buffer_arena, (vm_offset_t)bp->b_kvabase, bp->b_kvasize);
2004 counter_u64_add(bufkvaspace, -bp->b_kvasize);
2005 counter_u64_add(buffreekvacnt, 1);
2006 bp->b_data = bp->b_kvabase = unmapped_buf;
2013 * Allocate the buffer KVA and set b_kvasize and b_kvabase.
2016 bufkva_alloc(struct buf *bp, int maxsize, int gbflags)
2021 KASSERT((gbflags & GB_UNMAPPED) == 0 || (gbflags & GB_KVAALLOC) != 0,
2022 ("Invalid gbflags 0x%x in %s", gbflags, __func__));
2027 error = vmem_alloc(buffer_arena, maxsize, M_BESTFIT | M_NOWAIT, &addr);
2030 * Buffer map is too fragmented. Request the caller
2031 * to defragment the map.
2035 bp->b_kvabase = (caddr_t)addr;
2036 bp->b_kvasize = maxsize;
2037 counter_u64_add(bufkvaspace, bp->b_kvasize);
2038 if ((gbflags & GB_UNMAPPED) != 0) {
2039 bp->b_data = unmapped_buf;
2040 BUF_CHECK_UNMAPPED(bp);
2042 bp->b_data = bp->b_kvabase;
2043 BUF_CHECK_MAPPED(bp);
2051 * Reclaim buffer kva by freeing buffers holding kva. This is a vmem
2052 * callback that fires to avoid returning failure.
2055 bufkva_reclaim(vmem_t *vmem, int flags)
2062 for (i = 0; i < 5; i++) {
2063 for (q = 0; q < buf_domains; q++)
2064 if (buf_recycle(&bdomain[q], true) != 0)
2073 * Attempt to initiate asynchronous I/O on read-ahead blocks. We must
2074 * clear BIO_ERROR and B_INVAL prior to initiating I/O . If B_CACHE is set,
2075 * the buffer is valid and we do not have to do anything.
2078 breada(struct vnode * vp, daddr_t * rablkno, int * rabsize, int cnt,
2079 struct ucred * cred, int flags, void (*ckhashfunc)(struct buf *))
2087 for (i = 0; i < cnt; i++, rablkno++, rabsize++) {
2088 if (inmem(vp, *rablkno))
2090 rabp = getblk(vp, *rablkno, *rabsize, 0, 0, 0);
2091 if ((rabp->b_flags & B_CACHE) != 0) {
2098 racct_add_buf(curproc, rabp, 0);
2099 PROC_UNLOCK(curproc);
2102 td->td_ru.ru_inblock++;
2103 rabp->b_flags |= B_ASYNC;
2104 rabp->b_flags &= ~B_INVAL;
2105 if ((flags & GB_CKHASH) != 0) {
2106 rabp->b_flags |= B_CKHASH;
2107 rabp->b_ckhashcalc = ckhashfunc;
2109 rabp->b_ioflags &= ~BIO_ERROR;
2110 rabp->b_iocmd = BIO_READ;
2111 if (rabp->b_rcred == NOCRED && cred != NOCRED)
2112 rabp->b_rcred = crhold(cred);
2113 vfs_busy_pages(rabp, 0);
2115 rabp->b_iooffset = dbtob(rabp->b_blkno);
2121 * Entry point for bread() and breadn() via #defines in sys/buf.h.
2123 * Get a buffer with the specified data. Look in the cache first. We
2124 * must clear BIO_ERROR and B_INVAL prior to initiating I/O. If B_CACHE
2125 * is set, the buffer is valid and we do not have to do anything, see
2126 * getblk(). Also starts asynchronous I/O on read-ahead blocks.
2128 * Always return a NULL buffer pointer (in bpp) when returning an error.
2130 * The blkno parameter is the logical block being requested. Normally
2131 * the mapping of logical block number to disk block address is done
2132 * by calling VOP_BMAP(). However, if the mapping is already known, the
2133 * disk block address can be passed using the dblkno parameter. If the
2134 * disk block address is not known, then the same value should be passed
2135 * for blkno and dblkno.
2138 breadn_flags(struct vnode *vp, daddr_t blkno, daddr_t dblkno, int size,
2139 daddr_t *rablkno, int *rabsize, int cnt, struct ucred *cred, int flags,
2140 void (*ckhashfunc)(struct buf *), struct buf **bpp)
2144 int error, readwait, rv;
2146 CTR3(KTR_BUF, "breadn(%p, %jd, %d)", vp, blkno, size);
2149 * Can only return NULL if GB_LOCK_NOWAIT or GB_SPARSE flags
2152 error = getblkx(vp, blkno, dblkno, size, 0, 0, flags, &bp);
2157 KASSERT(blkno == bp->b_lblkno,
2158 ("getblkx returned buffer for blkno %jd instead of blkno %jd",
2159 (intmax_t)bp->b_lblkno, (intmax_t)blkno));
2160 flags &= ~GB_NOSPARSE;
2164 * If not found in cache, do some I/O
2167 if ((bp->b_flags & B_CACHE) == 0) {
2170 PROC_LOCK(td->td_proc);
2171 racct_add_buf(td->td_proc, bp, 0);
2172 PROC_UNLOCK(td->td_proc);
2175 td->td_ru.ru_inblock++;
2176 bp->b_iocmd = BIO_READ;
2177 bp->b_flags &= ~B_INVAL;
2178 if ((flags & GB_CKHASH) != 0) {
2179 bp->b_flags |= B_CKHASH;
2180 bp->b_ckhashcalc = ckhashfunc;
2182 bp->b_ioflags &= ~BIO_ERROR;
2183 if (bp->b_rcred == NOCRED && cred != NOCRED)
2184 bp->b_rcred = crhold(cred);
2185 vfs_busy_pages(bp, 0);
2186 bp->b_iooffset = dbtob(bp->b_blkno);
2192 * Attempt to initiate asynchronous I/O on read-ahead blocks.
2194 breada(vp, rablkno, rabsize, cnt, cred, flags, ckhashfunc);
2208 * Write, release buffer on completion. (Done by iodone
2209 * if async). Do not bother writing anything if the buffer
2212 * Note that we set B_CACHE here, indicating that buffer is
2213 * fully valid and thus cacheable. This is true even of NFS
2214 * now so we set it generally. This could be set either here
2215 * or in biodone() since the I/O is synchronous. We put it
2219 bufwrite(struct buf *bp)
2226 CTR3(KTR_BUF, "bufwrite(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
2227 if ((bp->b_bufobj->bo_flag & BO_DEAD) != 0) {
2228 bp->b_flags |= B_INVAL | B_RELBUF;
2229 bp->b_flags &= ~B_CACHE;
2233 if (bp->b_flags & B_INVAL) {
2238 if (bp->b_flags & B_BARRIER)
2239 atomic_add_long(&barrierwrites, 1);
2241 oldflags = bp->b_flags;
2243 KASSERT(!(bp->b_vflags & BV_BKGRDINPROG),
2244 ("FFS background buffer should not get here %p", bp));
2248 vp_md = vp->v_vflag & VV_MD;
2253 * Mark the buffer clean. Increment the bufobj write count
2254 * before bundirty() call, to prevent other thread from seeing
2255 * empty dirty list and zero counter for writes in progress,
2256 * falsely indicating that the bufobj is clean.
2258 bufobj_wref(bp->b_bufobj);
2261 bp->b_flags &= ~B_DONE;
2262 bp->b_ioflags &= ~BIO_ERROR;
2263 bp->b_flags |= B_CACHE;
2264 bp->b_iocmd = BIO_WRITE;
2266 vfs_busy_pages(bp, 1);
2269 * Normal bwrites pipeline writes
2271 bp->b_runningbufspace = bp->b_bufsize;
2272 space = atomic_fetchadd_long(&runningbufspace, bp->b_runningbufspace);
2277 racct_add_buf(curproc, bp, 1);
2278 PROC_UNLOCK(curproc);
2281 curthread->td_ru.ru_oublock++;
2282 if (oldflags & B_ASYNC)
2284 bp->b_iooffset = dbtob(bp->b_blkno);
2285 buf_track(bp, __func__);
2288 if ((oldflags & B_ASYNC) == 0) {
2289 int rtval = bufwait(bp);
2292 } else if (space > hirunningspace) {
2294 * don't allow the async write to saturate the I/O
2295 * system. We will not deadlock here because
2296 * we are blocking waiting for I/O that is already in-progress
2297 * to complete. We do not block here if it is the update
2298 * or syncer daemon trying to clean up as that can lead
2301 if ((curthread->td_pflags & TDP_NORUNNINGBUF) == 0 && !vp_md)
2302 waitrunningbufspace();
2309 bufbdflush(struct bufobj *bo, struct buf *bp)
2313 if (bo->bo_dirty.bv_cnt > dirtybufthresh + 10) {
2314 (void) VOP_FSYNC(bp->b_vp, MNT_NOWAIT, curthread);
2316 } else if (bo->bo_dirty.bv_cnt > dirtybufthresh) {
2319 * Try to find a buffer to flush.
2321 TAILQ_FOREACH(nbp, &bo->bo_dirty.bv_hd, b_bobufs) {
2322 if ((nbp->b_vflags & BV_BKGRDINPROG) ||
2324 LK_EXCLUSIVE | LK_NOWAIT, NULL))
2327 panic("bdwrite: found ourselves");
2329 /* Don't countdeps with the bo lock held. */
2330 if (buf_countdeps(nbp, 0)) {
2335 if (nbp->b_flags & B_CLUSTEROK) {
2336 vfs_bio_awrite(nbp);
2341 dirtybufferflushes++;
2350 * Delayed write. (Buffer is marked dirty). Do not bother writing
2351 * anything if the buffer is marked invalid.
2353 * Note that since the buffer must be completely valid, we can safely
2354 * set B_CACHE. In fact, we have to set B_CACHE here rather then in
2355 * biodone() in order to prevent getblk from writing the buffer
2356 * out synchronously.
2359 bdwrite(struct buf *bp)
2361 struct thread *td = curthread;
2365 CTR3(KTR_BUF, "bdwrite(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
2366 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp));
2367 KASSERT((bp->b_flags & B_BARRIER) == 0,
2368 ("Barrier request in delayed write %p", bp));
2370 if (bp->b_flags & B_INVAL) {
2376 * If we have too many dirty buffers, don't create any more.
2377 * If we are wildly over our limit, then force a complete
2378 * cleanup. Otherwise, just keep the situation from getting
2379 * out of control. Note that we have to avoid a recursive
2380 * disaster and not try to clean up after our own cleanup!
2384 if ((td->td_pflags & (TDP_COWINPROGRESS|TDP_INBDFLUSH)) == 0) {
2385 td->td_pflags |= TDP_INBDFLUSH;
2387 td->td_pflags &= ~TDP_INBDFLUSH;
2393 * Set B_CACHE, indicating that the buffer is fully valid. This is
2394 * true even of NFS now.
2396 bp->b_flags |= B_CACHE;
2399 * This bmap keeps the system from needing to do the bmap later,
2400 * perhaps when the system is attempting to do a sync. Since it
2401 * is likely that the indirect block -- or whatever other datastructure
2402 * that the filesystem needs is still in memory now, it is a good
2403 * thing to do this. Note also, that if the pageout daemon is
2404 * requesting a sync -- there might not be enough memory to do
2405 * the bmap then... So, this is important to do.
2407 if (vp->v_type != VCHR && bp->b_lblkno == bp->b_blkno) {
2408 VOP_BMAP(vp, bp->b_lblkno, NULL, &bp->b_blkno, NULL, NULL);
2411 buf_track(bp, __func__);
2414 * Set the *dirty* buffer range based upon the VM system dirty
2417 * Mark the buffer pages as clean. We need to do this here to
2418 * satisfy the vnode_pager and the pageout daemon, so that it
2419 * thinks that the pages have been "cleaned". Note that since
2420 * the pages are in a delayed write buffer -- the VFS layer
2421 * "will" see that the pages get written out on the next sync,
2422 * or perhaps the cluster will be completed.
2424 vfs_clean_pages_dirty_buf(bp);
2428 * note: we cannot initiate I/O from a bdwrite even if we wanted to,
2429 * due to the softdep code.
2436 * Turn buffer into delayed write request. We must clear BIO_READ and
2437 * B_RELBUF, and we must set B_DELWRI. We reassign the buffer to
2438 * itself to properly update it in the dirty/clean lists. We mark it
2439 * B_DONE to ensure that any asynchronization of the buffer properly
2440 * clears B_DONE ( else a panic will occur later ).
2442 * bdirty() is kinda like bdwrite() - we have to clear B_INVAL which
2443 * might have been set pre-getblk(). Unlike bwrite/bdwrite, bdirty()
2444 * should only be called if the buffer is known-good.
2446 * Since the buffer is not on a queue, we do not update the numfreebuffers
2449 * The buffer must be on QUEUE_NONE.
2452 bdirty(struct buf *bp)
2455 CTR3(KTR_BUF, "bdirty(%p) vp %p flags %X",
2456 bp, bp->b_vp, bp->b_flags);
2457 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp));
2458 KASSERT(bp->b_flags & B_REMFREE || bp->b_qindex == QUEUE_NONE,
2459 ("bdirty: buffer %p still on queue %d", bp, bp->b_qindex));
2460 bp->b_flags &= ~(B_RELBUF);
2461 bp->b_iocmd = BIO_WRITE;
2463 if ((bp->b_flags & B_DELWRI) == 0) {
2464 bp->b_flags |= /* XXX B_DONE | */ B_DELWRI;
2473 * Clear B_DELWRI for buffer.
2475 * Since the buffer is not on a queue, we do not update the numfreebuffers
2478 * The buffer must be on QUEUE_NONE.
2482 bundirty(struct buf *bp)
2485 CTR3(KTR_BUF, "bundirty(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
2486 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp));
2487 KASSERT(bp->b_flags & B_REMFREE || bp->b_qindex == QUEUE_NONE,
2488 ("bundirty: buffer %p still on queue %d", bp, bp->b_qindex));
2490 if (bp->b_flags & B_DELWRI) {
2491 bp->b_flags &= ~B_DELWRI;
2496 * Since it is now being written, we can clear its deferred write flag.
2498 bp->b_flags &= ~B_DEFERRED;
2504 * Asynchronous write. Start output on a buffer, but do not wait for
2505 * it to complete. The buffer is released when the output completes.
2507 * bwrite() ( or the VOP routine anyway ) is responsible for handling
2508 * B_INVAL buffers. Not us.
2511 bawrite(struct buf *bp)
2514 bp->b_flags |= B_ASYNC;
2521 * Asynchronous barrier write. Start output on a buffer, but do not
2522 * wait for it to complete. Place a write barrier after this write so
2523 * that this buffer and all buffers written before it are committed to
2524 * the disk before any buffers written after this write are committed
2525 * to the disk. The buffer is released when the output completes.
2528 babarrierwrite(struct buf *bp)
2531 bp->b_flags |= B_ASYNC | B_BARRIER;
2538 * Synchronous barrier write. Start output on a buffer and wait for
2539 * it to complete. Place a write barrier after this write so that
2540 * this buffer and all buffers written before it are committed to
2541 * the disk before any buffers written after this write are committed
2542 * to the disk. The buffer is released when the output completes.
2545 bbarrierwrite(struct buf *bp)
2548 bp->b_flags |= B_BARRIER;
2549 return (bwrite(bp));
2555 * Called prior to the locking of any vnodes when we are expecting to
2556 * write. We do not want to starve the buffer cache with too many
2557 * dirty buffers so we block here. By blocking prior to the locking
2558 * of any vnodes we attempt to avoid the situation where a locked vnode
2559 * prevents the various system daemons from flushing related buffers.
2565 if (buf_dirty_count_severe()) {
2566 mtx_lock(&bdirtylock);
2567 while (buf_dirty_count_severe()) {
2569 msleep(&bdirtywait, &bdirtylock, (PRIBIO + 4),
2572 mtx_unlock(&bdirtylock);
2577 * Return true if we have too many dirty buffers.
2580 buf_dirty_count_severe(void)
2583 return (!BIT_EMPTY(BUF_DOMAINS, &bdhidirty));
2589 * Release a busy buffer and, if requested, free its resources. The
2590 * buffer will be stashed in the appropriate bufqueue[] allowing it
2591 * to be accessed later as a cache entity or reused for other purposes.
2594 brelse(struct buf *bp)
2596 struct mount *v_mnt;
2600 * Many functions erroneously call brelse with a NULL bp under rare
2601 * error conditions. Simply return when called with a NULL bp.
2605 CTR3(KTR_BUF, "brelse(%p) vp %p flags %X",
2606 bp, bp->b_vp, bp->b_flags);
2607 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)),
2608 ("brelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp));
2609 KASSERT((bp->b_flags & B_VMIO) != 0 || (bp->b_flags & B_NOREUSE) == 0,
2610 ("brelse: non-VMIO buffer marked NOREUSE"));
2612 if (BUF_LOCKRECURSED(bp)) {
2614 * Do not process, in particular, do not handle the
2615 * B_INVAL/B_RELBUF and do not release to free list.
2621 if (bp->b_flags & B_MANAGED) {
2626 if ((bp->b_vflags & (BV_BKGRDINPROG | BV_BKGRDERR)) == BV_BKGRDERR) {
2627 BO_LOCK(bp->b_bufobj);
2628 bp->b_vflags &= ~BV_BKGRDERR;
2629 BO_UNLOCK(bp->b_bufobj);
2633 if (bp->b_iocmd == BIO_WRITE && (bp->b_ioflags & BIO_ERROR) &&
2634 (bp->b_flags & B_INVALONERR)) {
2636 * Forced invalidation of dirty buffer contents, to be used
2637 * after a failed write in the rare case that the loss of the
2638 * contents is acceptable. The buffer is invalidated and
2641 bp->b_flags |= B_INVAL | B_RELBUF | B_NOCACHE;
2642 bp->b_flags &= ~(B_ASYNC | B_CACHE);
2645 if (bp->b_iocmd == BIO_WRITE && (bp->b_ioflags & BIO_ERROR) &&
2646 (bp->b_error != ENXIO || !LIST_EMPTY(&bp->b_dep)) &&
2647 !(bp->b_flags & B_INVAL)) {
2649 * Failed write, redirty. All errors except ENXIO (which
2650 * means the device is gone) are treated as being
2653 * XXX Treating EIO as transient is not correct; the
2654 * contract with the local storage device drivers is that
2655 * they will only return EIO once the I/O is no longer
2656 * retriable. Network I/O also respects this through the
2657 * guarantees of TCP and/or the internal retries of NFS.
2658 * ENOMEM might be transient, but we also have no way of
2659 * knowing when its ok to retry/reschedule. In general,
2660 * this entire case should be made obsolete through better
2661 * error handling/recovery and resource scheduling.
2663 * Do this also for buffers that failed with ENXIO, but have
2664 * non-empty dependencies - the soft updates code might need
2665 * to access the buffer to untangle them.
2667 * Must clear BIO_ERROR to prevent pages from being scrapped.
2669 bp->b_ioflags &= ~BIO_ERROR;
2671 } else if ((bp->b_flags & (B_NOCACHE | B_INVAL)) ||
2672 (bp->b_ioflags & BIO_ERROR) || (bp->b_bufsize <= 0)) {
2674 * Either a failed read I/O, or we were asked to free or not
2675 * cache the buffer, or we failed to write to a device that's
2676 * no longer present.
2678 bp->b_flags |= B_INVAL;
2679 if (!LIST_EMPTY(&bp->b_dep))
2681 if (bp->b_flags & B_DELWRI)
2683 bp->b_flags &= ~(B_DELWRI | B_CACHE);
2684 if ((bp->b_flags & B_VMIO) == 0) {
2692 * We must clear B_RELBUF if B_DELWRI is set. If vfs_vmio_truncate()
2693 * is called with B_DELWRI set, the underlying pages may wind up
2694 * getting freed causing a previous write (bdwrite()) to get 'lost'
2695 * because pages associated with a B_DELWRI bp are marked clean.
2697 * We still allow the B_INVAL case to call vfs_vmio_truncate(), even
2698 * if B_DELWRI is set.
2700 if (bp->b_flags & B_DELWRI)
2701 bp->b_flags &= ~B_RELBUF;
2704 * VMIO buffer rundown. It is not very necessary to keep a VMIO buffer
2705 * constituted, not even NFS buffers now. Two flags effect this. If
2706 * B_INVAL, the struct buf is invalidated but the VM object is kept
2707 * around ( i.e. so it is trivial to reconstitute the buffer later ).
2709 * If BIO_ERROR or B_NOCACHE is set, pages in the VM object will be
2710 * invalidated. BIO_ERROR cannot be set for a failed write unless the
2711 * buffer is also B_INVAL because it hits the re-dirtying code above.
2713 * Normally we can do this whether a buffer is B_DELWRI or not. If
2714 * the buffer is an NFS buffer, it is tracking piecemeal writes or
2715 * the commit state and we cannot afford to lose the buffer. If the
2716 * buffer has a background write in progress, we need to keep it
2717 * around to prevent it from being reconstituted and starting a second
2721 v_mnt = bp->b_vp != NULL ? bp->b_vp->v_mount : NULL;
2723 if ((bp->b_flags & B_VMIO) && (bp->b_flags & B_NOCACHE ||
2724 (bp->b_ioflags & BIO_ERROR && bp->b_iocmd == BIO_READ)) &&
2725 (v_mnt == NULL || (v_mnt->mnt_vfc->vfc_flags & VFCF_NETWORK) == 0 ||
2726 vn_isdisk(bp->b_vp, NULL) || (bp->b_flags & B_DELWRI) == 0)) {
2727 vfs_vmio_invalidate(bp);
2731 if ((bp->b_flags & (B_INVAL | B_RELBUF)) != 0 ||
2732 (bp->b_flags & (B_DELWRI | B_NOREUSE)) == B_NOREUSE) {
2734 bp->b_flags &= ~B_NOREUSE;
2735 if (bp->b_vp != NULL)
2740 * If the buffer has junk contents signal it and eventually
2741 * clean up B_DELWRI and diassociate the vnode so that gbincore()
2744 if (bp->b_bufsize == 0 || (bp->b_ioflags & BIO_ERROR) != 0 ||
2745 (bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF)) != 0)
2746 bp->b_flags |= B_INVAL;
2747 if (bp->b_flags & B_INVAL) {
2748 if (bp->b_flags & B_DELWRI)
2754 buf_track(bp, __func__);
2756 /* buffers with no memory */
2757 if (bp->b_bufsize == 0) {
2761 /* buffers with junk contents */
2762 if (bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF) ||
2763 (bp->b_ioflags & BIO_ERROR)) {
2764 bp->b_xflags &= ~(BX_BKGRDWRITE | BX_ALTDATA);
2765 if (bp->b_vflags & BV_BKGRDINPROG)
2766 panic("losing buffer 2");
2767 qindex = QUEUE_CLEAN;
2768 bp->b_flags |= B_AGE;
2769 /* remaining buffers */
2770 } else if (bp->b_flags & B_DELWRI)
2771 qindex = QUEUE_DIRTY;
2773 qindex = QUEUE_CLEAN;
2775 if ((bp->b_flags & B_DELWRI) == 0 && (bp->b_xflags & BX_VNDIRTY))
2776 panic("brelse: not dirty");
2778 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_RELBUF | B_DIRECT);
2779 /* binsfree unlocks bp. */
2780 binsfree(bp, qindex);
2784 * Release a buffer back to the appropriate queue but do not try to free
2785 * it. The buffer is expected to be used again soon.
2787 * bqrelse() is used by bdwrite() to requeue a delayed write, and used by
2788 * biodone() to requeue an async I/O on completion. It is also used when
2789 * known good buffers need to be requeued but we think we may need the data
2792 * XXX we should be able to leave the B_RELBUF hint set on completion.
2795 bqrelse(struct buf *bp)
2799 CTR3(KTR_BUF, "bqrelse(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
2800 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)),
2801 ("bqrelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp));
2803 qindex = QUEUE_NONE;
2804 if (BUF_LOCKRECURSED(bp)) {
2805 /* do not release to free list */
2809 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF);
2811 if (bp->b_flags & B_MANAGED) {
2812 if (bp->b_flags & B_REMFREE)
2817 /* buffers with stale but valid contents */
2818 if ((bp->b_flags & B_DELWRI) != 0 || (bp->b_vflags & (BV_BKGRDINPROG |
2819 BV_BKGRDERR)) == BV_BKGRDERR) {
2820 BO_LOCK(bp->b_bufobj);
2821 bp->b_vflags &= ~BV_BKGRDERR;
2822 BO_UNLOCK(bp->b_bufobj);
2823 qindex = QUEUE_DIRTY;
2825 if ((bp->b_flags & B_DELWRI) == 0 &&
2826 (bp->b_xflags & BX_VNDIRTY))
2827 panic("bqrelse: not dirty");
2828 if ((bp->b_flags & B_NOREUSE) != 0) {
2832 qindex = QUEUE_CLEAN;
2834 buf_track(bp, __func__);
2835 /* binsfree unlocks bp. */
2836 binsfree(bp, qindex);
2840 buf_track(bp, __func__);
2846 * Complete I/O to a VMIO backed page. Validate the pages as appropriate,
2847 * restore bogus pages.
2850 vfs_vmio_iodone(struct buf *bp)
2855 struct vnode *vp __unused;
2856 int i, iosize, resid;
2859 obj = bp->b_bufobj->bo_object;
2860 KASSERT(REFCOUNT_COUNT(obj->paging_in_progress) >= bp->b_npages,
2861 ("vfs_vmio_iodone: paging in progress(%d) < b_npages(%d)",
2862 REFCOUNT_COUNT(obj->paging_in_progress), bp->b_npages));
2865 KASSERT(vp->v_holdcnt > 0,
2866 ("vfs_vmio_iodone: vnode %p has zero hold count", vp));
2867 KASSERT(vp->v_object != NULL,
2868 ("vfs_vmio_iodone: vnode %p has no vm_object", vp));
2870 foff = bp->b_offset;
2871 KASSERT(bp->b_offset != NOOFFSET,
2872 ("vfs_vmio_iodone: bp %p has no buffer offset", bp));
2875 iosize = bp->b_bcount - bp->b_resid;
2876 for (i = 0; i < bp->b_npages; i++) {
2877 resid = ((foff + PAGE_SIZE) & ~(off_t)PAGE_MASK) - foff;
2882 * cleanup bogus pages, restoring the originals
2885 if (m == bogus_page) {
2886 if (bogus == false) {
2888 VM_OBJECT_RLOCK(obj);
2890 m = vm_page_lookup(obj, OFF_TO_IDX(foff));
2892 panic("biodone: page disappeared!");
2894 } else if ((bp->b_iocmd == BIO_READ) && resid > 0) {
2896 * In the write case, the valid and clean bits are
2897 * already changed correctly ( see bdwrite() ), so we
2898 * only need to do this here in the read case.
2900 KASSERT((m->dirty & vm_page_bits(foff & PAGE_MASK,
2901 resid)) == 0, ("vfs_vmio_iodone: page %p "
2902 "has unexpected dirty bits", m));
2903 vfs_page_set_valid(bp, foff, m);
2905 KASSERT(OFF_TO_IDX(foff) == m->pindex,
2906 ("vfs_vmio_iodone: foff(%jd)/pindex(%ju) mismatch",
2907 (intmax_t)foff, (uintmax_t)m->pindex));
2910 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK;
2914 VM_OBJECT_RUNLOCK(obj);
2915 vm_object_pip_wakeupn(obj, bp->b_npages);
2916 if (bogus && buf_mapped(bp)) {
2917 BUF_CHECK_MAPPED(bp);
2918 pmap_qenter(trunc_page((vm_offset_t)bp->b_data),
2919 bp->b_pages, bp->b_npages);
2924 * Perform page invalidation when a buffer is released. The fully invalid
2925 * pages will be reclaimed later in vfs_vmio_truncate().
2928 vfs_vmio_invalidate(struct buf *bp)
2932 int flags, i, resid, poffset, presid;
2934 if (buf_mapped(bp)) {
2935 BUF_CHECK_MAPPED(bp);
2936 pmap_qremove(trunc_page((vm_offset_t)bp->b_data), bp->b_npages);
2938 BUF_CHECK_UNMAPPED(bp);
2940 * Get the base offset and length of the buffer. Note that
2941 * in the VMIO case if the buffer block size is not
2942 * page-aligned then b_data pointer may not be page-aligned.
2943 * But our b_pages[] array *IS* page aligned.
2945 * block sizes less then DEV_BSIZE (usually 512) are not
2946 * supported due to the page granularity bits (m->valid,
2947 * m->dirty, etc...).
2949 * See man buf(9) for more information
2951 flags = (bp->b_flags & B_NOREUSE) != 0 ? VPR_NOREUSE : 0;
2952 obj = bp->b_bufobj->bo_object;
2953 resid = bp->b_bufsize;
2954 poffset = bp->b_offset & PAGE_MASK;
2955 VM_OBJECT_WLOCK(obj);
2956 for (i = 0; i < bp->b_npages; i++) {
2958 if (m == bogus_page)
2959 panic("vfs_vmio_invalidate: Unexpected bogus page.");
2960 bp->b_pages[i] = NULL;
2962 presid = resid > (PAGE_SIZE - poffset) ?
2963 (PAGE_SIZE - poffset) : resid;
2964 KASSERT(presid >= 0, ("brelse: extra page"));
2965 vm_page_busy_acquire(m, VM_ALLOC_SBUSY);
2966 if (pmap_page_wired_mappings(m) == 0)
2967 vm_page_set_invalid(m, poffset, presid);
2969 vm_page_release_locked(m, flags);
2973 VM_OBJECT_WUNLOCK(obj);
2978 * Page-granular truncation of an existing VMIO buffer.
2981 vfs_vmio_truncate(struct buf *bp, int desiredpages)
2987 if (bp->b_npages == desiredpages)
2990 if (buf_mapped(bp)) {
2991 BUF_CHECK_MAPPED(bp);
2992 pmap_qremove((vm_offset_t)trunc_page((vm_offset_t)bp->b_data) +
2993 (desiredpages << PAGE_SHIFT), bp->b_npages - desiredpages);
2995 BUF_CHECK_UNMAPPED(bp);
2998 * The object lock is needed only if we will attempt to free pages.
3000 flags = (bp->b_flags & B_NOREUSE) != 0 ? VPR_NOREUSE : 0;
3001 if ((bp->b_flags & B_DIRECT) != 0) {
3002 flags |= VPR_TRYFREE;
3003 obj = bp->b_bufobj->bo_object;
3004 VM_OBJECT_WLOCK(obj);
3008 for (i = desiredpages; i < bp->b_npages; i++) {
3010 KASSERT(m != bogus_page, ("allocbuf: bogus page found"));
3011 bp->b_pages[i] = NULL;
3013 vm_page_release_locked(m, flags);
3015 vm_page_release(m, flags);
3018 VM_OBJECT_WUNLOCK(obj);
3019 bp->b_npages = desiredpages;
3023 * Byte granular extension of VMIO buffers.
3026 vfs_vmio_extend(struct buf *bp, int desiredpages, int size)
3029 * We are growing the buffer, possibly in a
3030 * byte-granular fashion.
3038 * Step 1, bring in the VM pages from the object, allocating
3039 * them if necessary. We must clear B_CACHE if these pages
3040 * are not valid for the range covered by the buffer.
3042 obj = bp->b_bufobj->bo_object;
3043 if (bp->b_npages < desiredpages) {
3045 * We must allocate system pages since blocking
3046 * here could interfere with paging I/O, no
3047 * matter which process we are.
3049 * Only exclusive busy can be tested here.
3050 * Blocking on shared busy might lead to
3051 * deadlocks once allocbuf() is called after
3052 * pages are vfs_busy_pages().
3054 VM_OBJECT_WLOCK(obj);
3055 (void)vm_page_grab_pages(obj,
3056 OFF_TO_IDX(bp->b_offset) + bp->b_npages,
3057 VM_ALLOC_SYSTEM | VM_ALLOC_IGN_SBUSY |
3058 VM_ALLOC_NOBUSY | VM_ALLOC_WIRED,
3059 &bp->b_pages[bp->b_npages], desiredpages - bp->b_npages);
3060 VM_OBJECT_WUNLOCK(obj);
3061 bp->b_npages = desiredpages;
3065 * Step 2. We've loaded the pages into the buffer,
3066 * we have to figure out if we can still have B_CACHE
3067 * set. Note that B_CACHE is set according to the
3068 * byte-granular range ( bcount and size ), not the
3069 * aligned range ( newbsize ).
3071 * The VM test is against m->valid, which is DEV_BSIZE
3072 * aligned. Needless to say, the validity of the data
3073 * needs to also be DEV_BSIZE aligned. Note that this
3074 * fails with NFS if the server or some other client
3075 * extends the file's EOF. If our buffer is resized,
3076 * B_CACHE may remain set! XXX
3078 toff = bp->b_bcount;
3079 tinc = PAGE_SIZE - ((bp->b_offset + toff) & PAGE_MASK);
3080 while ((bp->b_flags & B_CACHE) && toff < size) {
3083 if (tinc > (size - toff))
3085 pi = ((bp->b_offset & PAGE_MASK) + toff) >> PAGE_SHIFT;
3086 m = bp->b_pages[pi];
3087 vfs_buf_test_cache(bp, bp->b_offset, toff, tinc, m);
3093 * Step 3, fixup the KVA pmap.
3098 BUF_CHECK_UNMAPPED(bp);
3102 * Check to see if a block at a particular lbn is available for a clustered
3106 vfs_bio_clcheck(struct vnode *vp, int size, daddr_t lblkno, daddr_t blkno)
3113 /* If the buf isn't in core skip it */
3114 if ((bpa = gbincore(&vp->v_bufobj, lblkno)) == NULL)
3117 /* If the buf is busy we don't want to wait for it */
3118 if (BUF_LOCK(bpa, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0)
3121 /* Only cluster with valid clusterable delayed write buffers */
3122 if ((bpa->b_flags & (B_DELWRI | B_CLUSTEROK | B_INVAL)) !=
3123 (B_DELWRI | B_CLUSTEROK))
3126 if (bpa->b_bufsize != size)
3130 * Check to see if it is in the expected place on disk and that the
3131 * block has been mapped.
3133 if ((bpa->b_blkno != bpa->b_lblkno) && (bpa->b_blkno == blkno))
3143 * Implement clustered async writes for clearing out B_DELWRI buffers.
3144 * This is much better then the old way of writing only one buffer at
3145 * a time. Note that we may not be presented with the buffers in the
3146 * correct order, so we search for the cluster in both directions.
3149 vfs_bio_awrite(struct buf *bp)
3154 daddr_t lblkno = bp->b_lblkno;
3155 struct vnode *vp = bp->b_vp;
3163 gbflags = (bp->b_data == unmapped_buf) ? GB_UNMAPPED : 0;
3165 * right now we support clustered writing only to regular files. If
3166 * we find a clusterable block we could be in the middle of a cluster
3167 * rather then at the beginning.
3169 if ((vp->v_type == VREG) &&
3170 (vp->v_mount != 0) && /* Only on nodes that have the size info */
3171 (bp->b_flags & (B_CLUSTEROK | B_INVAL)) == B_CLUSTEROK) {
3173 size = vp->v_mount->mnt_stat.f_iosize;
3174 maxcl = MAXPHYS / size;
3177 for (i = 1; i < maxcl; i++)
3178 if (vfs_bio_clcheck(vp, size, lblkno + i,
3179 bp->b_blkno + ((i * size) >> DEV_BSHIFT)) == 0)
3182 for (j = 1; i + j <= maxcl && j <= lblkno; j++)
3183 if (vfs_bio_clcheck(vp, size, lblkno - j,
3184 bp->b_blkno - ((j * size) >> DEV_BSHIFT)) == 0)
3190 * this is a possible cluster write
3194 nwritten = cluster_wbuild(vp, size, lblkno - j, ncl,
3200 bp->b_flags |= B_ASYNC;
3202 * default (old) behavior, writing out only one block
3204 * XXX returns b_bufsize instead of b_bcount for nwritten?
3206 nwritten = bp->b_bufsize;
3215 * Allocate KVA for an empty buf header according to gbflags.
3218 getnewbuf_kva(struct buf *bp, int gbflags, int maxsize)
3221 if ((gbflags & (GB_UNMAPPED | GB_KVAALLOC)) != GB_UNMAPPED) {
3223 * In order to keep fragmentation sane we only allocate kva
3224 * in BKVASIZE chunks. XXX with vmem we can do page size.
3226 maxsize = (maxsize + BKVAMASK) & ~BKVAMASK;
3228 if (maxsize != bp->b_kvasize &&
3229 bufkva_alloc(bp, maxsize, gbflags))
3238 * Find and initialize a new buffer header, freeing up existing buffers
3239 * in the bufqueues as necessary. The new buffer is returned locked.
3242 * We have insufficient buffer headers
3243 * We have insufficient buffer space
3244 * buffer_arena is too fragmented ( space reservation fails )
3245 * If we have to flush dirty buffers ( but we try to avoid this )
3247 * The caller is responsible for releasing the reserved bufspace after
3248 * allocbuf() is called.
3251 getnewbuf(struct vnode *vp, int slpflag, int slptimeo, int maxsize, int gbflags)
3253 struct bufdomain *bd;
3255 bool metadata, reserved;
3258 KASSERT((gbflags & (GB_UNMAPPED | GB_KVAALLOC)) != GB_KVAALLOC,
3259 ("GB_KVAALLOC only makes sense with GB_UNMAPPED"));
3260 if (!unmapped_buf_allowed)
3261 gbflags &= ~(GB_UNMAPPED | GB_KVAALLOC);
3263 if (vp == NULL || (vp->v_vflag & (VV_MD | VV_SYSTEM)) != 0 ||
3271 bd = &bdomain[vp->v_bufobj.bo_domain];
3273 counter_u64_add(getnewbufcalls, 1);
3276 if (reserved == false &&
3277 bufspace_reserve(bd, maxsize, metadata) != 0) {
3278 counter_u64_add(getnewbufrestarts, 1);
3282 if ((bp = buf_alloc(bd)) == NULL) {
3283 counter_u64_add(getnewbufrestarts, 1);
3286 if (getnewbuf_kva(bp, gbflags, maxsize) == 0)
3289 } while (buf_recycle(bd, false) == 0);
3292 bufspace_release(bd, maxsize);
3294 bp->b_flags |= B_INVAL;
3297 bufspace_wait(bd, vp, gbflags, slpflag, slptimeo);
3305 * buffer flushing daemon. Buffers are normally flushed by the
3306 * update daemon but if it cannot keep up this process starts to
3307 * take the load in an attempt to prevent getnewbuf() from blocking.
3309 static struct kproc_desc buf_kp = {
3314 SYSINIT(bufdaemon, SI_SUB_KTHREAD_BUF, SI_ORDER_FIRST, kproc_start, &buf_kp);
3317 buf_flush(struct vnode *vp, struct bufdomain *bd, int target)
3321 flushed = flushbufqueues(vp, bd, target, 0);
3324 * Could not find any buffers without rollback
3325 * dependencies, so just write the first one
3326 * in the hopes of eventually making progress.
3328 if (vp != NULL && target > 2)
3330 flushbufqueues(vp, bd, target, 1);
3338 struct bufdomain *bd;
3344 * This process needs to be suspended prior to shutdown sync.
3346 EVENTHANDLER_REGISTER(shutdown_pre_sync, kthread_shutdown, curthread,
3347 SHUTDOWN_PRI_LAST + 100);
3350 * Start the buf clean daemons as children threads.
3352 for (i = 0 ; i < buf_domains; i++) {
3355 error = kthread_add((void (*)(void *))bufspace_daemon,
3356 &bdomain[i], curproc, NULL, 0, 0, "bufspacedaemon-%d", i);
3358 panic("error %d spawning bufspace daemon", error);
3362 * This process is allowed to take the buffer cache to the limit
3364 curthread->td_pflags |= TDP_NORUNNINGBUF | TDP_BUFNEED;
3368 mtx_unlock(&bdlock);
3370 kthread_suspend_check();
3373 * Save speedupreq for this pass and reset to capture new
3376 speedupreq = bd_speedupreq;
3380 * Flush each domain sequentially according to its level and
3381 * the speedup request.
3383 for (i = 0; i < buf_domains; i++) {
3386 lodirty = bd->bd_numdirtybuffers / 2;
3388 lodirty = bd->bd_lodirtybuffers;
3389 while (bd->bd_numdirtybuffers > lodirty) {
3390 if (buf_flush(NULL, bd,
3391 bd->bd_numdirtybuffers - lodirty) == 0)
3393 kern_yield(PRI_USER);
3398 * Only clear bd_request if we have reached our low water
3399 * mark. The buf_daemon normally waits 1 second and
3400 * then incrementally flushes any dirty buffers that have
3401 * built up, within reason.
3403 * If we were unable to hit our low water mark and couldn't
3404 * find any flushable buffers, we sleep for a short period
3405 * to avoid endless loops on unlockable buffers.
3408 if (!BIT_EMPTY(BUF_DOMAINS, &bdlodirty)) {
3410 * We reached our low water mark, reset the
3411 * request and sleep until we are needed again.
3412 * The sleep is just so the suspend code works.
3416 * Do an extra wakeup in case dirty threshold
3417 * changed via sysctl and the explicit transition
3418 * out of shortfall was missed.
3421 if (runningbufspace <= lorunningspace)
3423 msleep(&bd_request, &bdlock, PVM, "psleep", hz);
3426 * We couldn't find any flushable dirty buffers but
3427 * still have too many dirty buffers, we
3428 * have to sleep and try again. (rare)
3430 msleep(&bd_request, &bdlock, PVM, "qsleep", hz / 10);
3438 * Try to flush a buffer in the dirty queue. We must be careful to
3439 * free up B_INVAL buffers instead of write them, which NFS is
3440 * particularly sensitive to.
3442 static int flushwithdeps = 0;
3443 SYSCTL_INT(_vfs, OID_AUTO, flushwithdeps, CTLFLAG_RW | CTLFLAG_STATS,
3445 "Number of buffers flushed with dependecies that require rollbacks");
3448 flushbufqueues(struct vnode *lvp, struct bufdomain *bd, int target,
3451 struct bufqueue *bq;
3452 struct buf *sentinel;
3462 bq = &bd->bd_dirtyq;
3464 sentinel = malloc(sizeof(struct buf), M_TEMP, M_WAITOK | M_ZERO);
3465 sentinel->b_qindex = QUEUE_SENTINEL;
3467 TAILQ_INSERT_HEAD(&bq->bq_queue, sentinel, b_freelist);
3469 while (flushed != target) {
3472 bp = TAILQ_NEXT(sentinel, b_freelist);
3474 TAILQ_REMOVE(&bq->bq_queue, sentinel, b_freelist);
3475 TAILQ_INSERT_AFTER(&bq->bq_queue, bp, sentinel,
3482 * Skip sentinels inserted by other invocations of the
3483 * flushbufqueues(), taking care to not reorder them.
3485 * Only flush the buffers that belong to the
3486 * vnode locked by the curthread.
3488 if (bp->b_qindex == QUEUE_SENTINEL || (lvp != NULL &&
3493 error = BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL);
3499 * BKGRDINPROG can only be set with the buf and bufobj
3500 * locks both held. We tolerate a race to clear it here.
3502 if ((bp->b_vflags & BV_BKGRDINPROG) != 0 ||
3503 (bp->b_flags & B_DELWRI) == 0) {
3507 if (bp->b_flags & B_INVAL) {
3514 if (!LIST_EMPTY(&bp->b_dep) && buf_countdeps(bp, 0)) {
3515 if (flushdeps == 0) {
3523 * We must hold the lock on a vnode before writing
3524 * one of its buffers. Otherwise we may confuse, or
3525 * in the case of a snapshot vnode, deadlock the
3528 * The lock order here is the reverse of the normal
3529 * of vnode followed by buf lock. This is ok because
3530 * the NOWAIT will prevent deadlock.
3533 if (vn_start_write(vp, &mp, V_NOWAIT) != 0) {
3539 error = vn_lock(vp, LK_EXCLUSIVE | LK_NOWAIT);
3541 ASSERT_VOP_LOCKED(vp, "getbuf");
3543 error = VOP_ISLOCKED(vp) == LK_EXCLUSIVE ? 0 :
3544 vn_lock(vp, LK_TRYUPGRADE);
3547 CTR3(KTR_BUF, "flushbufqueue(%p) vp %p flags %X",
3548 bp, bp->b_vp, bp->b_flags);
3549 if (curproc == bufdaemonproc) {
3554 counter_u64_add(notbufdflushes, 1);
3556 vn_finished_write(mp);
3559 flushwithdeps += hasdeps;
3563 * Sleeping on runningbufspace while holding
3564 * vnode lock leads to deadlock.
3566 if (curproc == bufdaemonproc &&
3567 runningbufspace > hirunningspace)
3568 waitrunningbufspace();
3571 vn_finished_write(mp);
3575 TAILQ_REMOVE(&bq->bq_queue, sentinel, b_freelist);
3577 free(sentinel, M_TEMP);
3582 * Check to see if a block is currently memory resident.
3585 incore(struct bufobj *bo, daddr_t blkno)
3590 bp = gbincore(bo, blkno);
3596 * Returns true if no I/O is needed to access the
3597 * associated VM object. This is like incore except
3598 * it also hunts around in the VM system for the data.
3602 inmem(struct vnode * vp, daddr_t blkno)
3605 vm_offset_t toff, tinc, size;
3609 ASSERT_VOP_LOCKED(vp, "inmem");
3611 if (incore(&vp->v_bufobj, blkno))
3613 if (vp->v_mount == NULL)
3620 if (size > vp->v_mount->mnt_stat.f_iosize)
3621 size = vp->v_mount->mnt_stat.f_iosize;
3622 off = (vm_ooffset_t)blkno * (vm_ooffset_t)vp->v_mount->mnt_stat.f_iosize;
3624 VM_OBJECT_RLOCK(obj);
3625 for (toff = 0; toff < vp->v_mount->mnt_stat.f_iosize; toff += tinc) {
3626 m = vm_page_lookup(obj, OFF_TO_IDX(off + toff));
3630 if (tinc > PAGE_SIZE - ((toff + off) & PAGE_MASK))
3631 tinc = PAGE_SIZE - ((toff + off) & PAGE_MASK);
3632 if (vm_page_is_valid(m,
3633 (vm_offset_t) ((toff + off) & PAGE_MASK), tinc) == 0)
3636 VM_OBJECT_RUNLOCK(obj);
3640 VM_OBJECT_RUNLOCK(obj);
3645 * Set the dirty range for a buffer based on the status of the dirty
3646 * bits in the pages comprising the buffer. The range is limited
3647 * to the size of the buffer.
3649 * Tell the VM system that the pages associated with this buffer
3650 * are clean. This is used for delayed writes where the data is
3651 * going to go to disk eventually without additional VM intevention.
3653 * Note that while we only really need to clean through to b_bcount, we
3654 * just go ahead and clean through to b_bufsize.
3657 vfs_clean_pages_dirty_buf(struct buf *bp)
3659 vm_ooffset_t foff, noff, eoff;
3663 if ((bp->b_flags & B_VMIO) == 0 || bp->b_bufsize == 0)
3666 foff = bp->b_offset;
3667 KASSERT(bp->b_offset != NOOFFSET,
3668 ("vfs_clean_pages_dirty_buf: no buffer offset"));
3670 vfs_busy_pages_acquire(bp);
3671 vfs_setdirty_range(bp);
3672 for (i = 0; i < bp->b_npages; i++) {
3673 noff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK;
3675 if (eoff > bp->b_offset + bp->b_bufsize)
3676 eoff = bp->b_offset + bp->b_bufsize;
3678 vfs_page_set_validclean(bp, foff, m);
3679 /* vm_page_clear_dirty(m, foff & PAGE_MASK, eoff - foff); */
3682 vfs_busy_pages_release(bp);
3686 vfs_setdirty_range(struct buf *bp)
3688 vm_offset_t boffset;
3689 vm_offset_t eoffset;
3693 * test the pages to see if they have been modified directly
3694 * by users through the VM system.
3696 for (i = 0; i < bp->b_npages; i++)
3697 vm_page_test_dirty(bp->b_pages[i]);
3700 * Calculate the encompassing dirty range, boffset and eoffset,
3701 * (eoffset - boffset) bytes.
3704 for (i = 0; i < bp->b_npages; i++) {
3705 if (bp->b_pages[i]->dirty)
3708 boffset = (i << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK);
3710 for (i = bp->b_npages - 1; i >= 0; --i) {
3711 if (bp->b_pages[i]->dirty) {
3715 eoffset = ((i + 1) << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK);
3718 * Fit it to the buffer.
3721 if (eoffset > bp->b_bcount)
3722 eoffset = bp->b_bcount;
3725 * If we have a good dirty range, merge with the existing
3729 if (boffset < eoffset) {
3730 if (bp->b_dirtyoff > boffset)
3731 bp->b_dirtyoff = boffset;
3732 if (bp->b_dirtyend < eoffset)
3733 bp->b_dirtyend = eoffset;
3738 * Allocate the KVA mapping for an existing buffer.
3739 * If an unmapped buffer is provided but a mapped buffer is requested, take
3740 * also care to properly setup mappings between pages and KVA.
3743 bp_unmapped_get_kva(struct buf *bp, daddr_t blkno, int size, int gbflags)
3745 int bsize, maxsize, need_mapping, need_kva;
3748 need_mapping = bp->b_data == unmapped_buf &&
3749 (gbflags & GB_UNMAPPED) == 0;
3750 need_kva = bp->b_kvabase == unmapped_buf &&
3751 bp->b_data == unmapped_buf &&
3752 (gbflags & GB_KVAALLOC) != 0;
3753 if (!need_mapping && !need_kva)
3756 BUF_CHECK_UNMAPPED(bp);
3758 if (need_mapping && bp->b_kvabase != unmapped_buf) {
3760 * Buffer is not mapped, but the KVA was already
3761 * reserved at the time of the instantiation. Use the
3768 * Calculate the amount of the address space we would reserve
3769 * if the buffer was mapped.
3771 bsize = vn_isdisk(bp->b_vp, NULL) ? DEV_BSIZE : bp->b_bufobj->bo_bsize;
3772 KASSERT(bsize != 0, ("bsize == 0, check bo->bo_bsize"));
3773 offset = blkno * bsize;
3774 maxsize = size + (offset & PAGE_MASK);
3775 maxsize = imax(maxsize, bsize);
3777 while (bufkva_alloc(bp, maxsize, gbflags) != 0) {
3778 if ((gbflags & GB_NOWAIT_BD) != 0) {
3780 * XXXKIB: defragmentation cannot
3781 * succeed, not sure what else to do.
3783 panic("GB_NOWAIT_BD and GB_UNMAPPED %p", bp);
3785 counter_u64_add(mappingrestarts, 1);
3786 bufspace_wait(bufdomain(bp), bp->b_vp, gbflags, 0, 0);
3790 /* b_offset is handled by bpmap_qenter. */
3791 bp->b_data = bp->b_kvabase;
3792 BUF_CHECK_MAPPED(bp);
3798 getblk(struct vnode *vp, daddr_t blkno, int size, int slpflag, int slptimeo,
3804 error = getblkx(vp, blkno, blkno, size, slpflag, slptimeo, flags, &bp);
3813 * Get a block given a specified block and offset into a file/device.
3814 * The buffers B_DONE bit will be cleared on return, making it almost
3815 * ready for an I/O initiation. B_INVAL may or may not be set on
3816 * return. The caller should clear B_INVAL prior to initiating a
3819 * For a non-VMIO buffer, B_CACHE is set to the opposite of B_INVAL for
3820 * an existing buffer.
3822 * For a VMIO buffer, B_CACHE is modified according to the backing VM.
3823 * If getblk()ing a previously 0-sized invalid buffer, B_CACHE is set
3824 * and then cleared based on the backing VM. If the previous buffer is
3825 * non-0-sized but invalid, B_CACHE will be cleared.
3827 * If getblk() must create a new buffer, the new buffer is returned with
3828 * both B_INVAL and B_CACHE clear unless it is a VMIO buffer, in which
3829 * case it is returned with B_INVAL clear and B_CACHE set based on the
3832 * getblk() also forces a bwrite() for any B_DELWRI buffer whose
3833 * B_CACHE bit is clear.
3835 * What this means, basically, is that the caller should use B_CACHE to
3836 * determine whether the buffer is fully valid or not and should clear
3837 * B_INVAL prior to issuing a read. If the caller intends to validate
3838 * the buffer by loading its data area with something, the caller needs
3839 * to clear B_INVAL. If the caller does this without issuing an I/O,
3840 * the caller should set B_CACHE ( as an optimization ), else the caller
3841 * should issue the I/O and biodone() will set B_CACHE if the I/O was
3842 * a write attempt or if it was a successful read. If the caller
3843 * intends to issue a READ, the caller must clear B_INVAL and BIO_ERROR
3844 * prior to issuing the READ. biodone() will *not* clear B_INVAL.
3846 * The blkno parameter is the logical block being requested. Normally
3847 * the mapping of logical block number to disk block address is done
3848 * by calling VOP_BMAP(). However, if the mapping is already known, the
3849 * disk block address can be passed using the dblkno parameter. If the
3850 * disk block address is not known, then the same value should be passed
3851 * for blkno and dblkno.
3854 getblkx(struct vnode *vp, daddr_t blkno, daddr_t dblkno, int size, int slpflag,
3855 int slptimeo, int flags, struct buf **bpp)
3860 int bsize, error, maxsize, vmio;
3863 CTR3(KTR_BUF, "getblk(%p, %ld, %d)", vp, (long)blkno, size);
3864 KASSERT((flags & (GB_UNMAPPED | GB_KVAALLOC)) != GB_KVAALLOC,
3865 ("GB_KVAALLOC only makes sense with GB_UNMAPPED"));
3866 ASSERT_VOP_LOCKED(vp, "getblk");
3867 if (size > maxbcachebuf)
3868 panic("getblk: size(%d) > maxbcachebuf(%d)\n", size,
3870 if (!unmapped_buf_allowed)
3871 flags &= ~(GB_UNMAPPED | GB_KVAALLOC);
3877 bp = gbincore(bo, blkno);
3881 * Buffer is in-core. If the buffer is not busy nor managed,
3882 * it must be on a queue.
3884 lockflags = LK_EXCLUSIVE | LK_SLEEPFAIL | LK_INTERLOCK;
3886 if ((flags & GB_LOCK_NOWAIT) != 0)
3887 lockflags |= LK_NOWAIT;
3889 error = BUF_TIMELOCK(bp, lockflags,
3890 BO_LOCKPTR(bo), "getblk", slpflag, slptimeo);
3893 * If we slept and got the lock we have to restart in case
3894 * the buffer changed identities.
3896 if (error == ENOLCK)
3898 /* We timed out or were interrupted. */
3899 else if (error != 0)
3901 /* If recursed, assume caller knows the rules. */
3902 else if (BUF_LOCKRECURSED(bp))
3906 * The buffer is locked. B_CACHE is cleared if the buffer is
3907 * invalid. Otherwise, for a non-VMIO buffer, B_CACHE is set
3908 * and for a VMIO buffer B_CACHE is adjusted according to the
3911 if (bp->b_flags & B_INVAL)
3912 bp->b_flags &= ~B_CACHE;
3913 else if ((bp->b_flags & (B_VMIO | B_INVAL)) == 0)
3914 bp->b_flags |= B_CACHE;
3915 if (bp->b_flags & B_MANAGED)
3916 MPASS(bp->b_qindex == QUEUE_NONE);
3921 * check for size inconsistencies for non-VMIO case.
3923 if (bp->b_bcount != size) {
3924 if ((bp->b_flags & B_VMIO) == 0 ||
3925 (size > bp->b_kvasize)) {
3926 if (bp->b_flags & B_DELWRI) {
3927 bp->b_flags |= B_NOCACHE;
3930 if (LIST_EMPTY(&bp->b_dep)) {
3931 bp->b_flags |= B_RELBUF;
3934 bp->b_flags |= B_NOCACHE;
3943 * Handle the case of unmapped buffer which should
3944 * become mapped, or the buffer for which KVA
3945 * reservation is requested.
3947 bp_unmapped_get_kva(bp, blkno, size, flags);
3950 * If the size is inconsistent in the VMIO case, we can resize
3951 * the buffer. This might lead to B_CACHE getting set or
3952 * cleared. If the size has not changed, B_CACHE remains
3953 * unchanged from its previous state.
3957 KASSERT(bp->b_offset != NOOFFSET,
3958 ("getblk: no buffer offset"));
3961 * A buffer with B_DELWRI set and B_CACHE clear must
3962 * be committed before we can return the buffer in
3963 * order to prevent the caller from issuing a read
3964 * ( due to B_CACHE not being set ) and overwriting
3967 * Most callers, including NFS and FFS, need this to
3968 * operate properly either because they assume they
3969 * can issue a read if B_CACHE is not set, or because
3970 * ( for example ) an uncached B_DELWRI might loop due
3971 * to softupdates re-dirtying the buffer. In the latter
3972 * case, B_CACHE is set after the first write completes,
3973 * preventing further loops.
3974 * NOTE! b*write() sets B_CACHE. If we cleared B_CACHE
3975 * above while extending the buffer, we cannot allow the
3976 * buffer to remain with B_CACHE set after the write
3977 * completes or it will represent a corrupt state. To
3978 * deal with this we set B_NOCACHE to scrap the buffer
3981 * We might be able to do something fancy, like setting
3982 * B_CACHE in bwrite() except if B_DELWRI is already set,
3983 * so the below call doesn't set B_CACHE, but that gets real
3984 * confusing. This is much easier.
3987 if ((bp->b_flags & (B_CACHE|B_DELWRI)) == B_DELWRI) {
3988 bp->b_flags |= B_NOCACHE;
3992 bp->b_flags &= ~B_DONE;
3995 * Buffer is not in-core, create new buffer. The buffer
3996 * returned by getnewbuf() is locked. Note that the returned
3997 * buffer is also considered valid (not marked B_INVAL).
4001 * If the user does not want us to create the buffer, bail out
4004 if (flags & GB_NOCREAT)
4007 bsize = vn_isdisk(vp, NULL) ? DEV_BSIZE : bo->bo_bsize;
4008 KASSERT(bsize != 0, ("bsize == 0, check bo->bo_bsize"));
4009 offset = blkno * bsize;
4010 vmio = vp->v_object != NULL;
4012 maxsize = size + (offset & PAGE_MASK);
4015 /* Do not allow non-VMIO notmapped buffers. */
4016 flags &= ~(GB_UNMAPPED | GB_KVAALLOC);
4018 maxsize = imax(maxsize, bsize);
4019 if ((flags & GB_NOSPARSE) != 0 && vmio &&
4020 !vn_isdisk(vp, NULL)) {
4021 error = VOP_BMAP(vp, blkno, NULL, &d_blkno, 0, 0);
4022 KASSERT(error != EOPNOTSUPP,
4023 ("GB_NOSPARSE from fs not supporting bmap, vp %p",
4028 return (EJUSTRETURN);
4031 bp = getnewbuf(vp, slpflag, slptimeo, maxsize, flags);
4033 if (slpflag || slptimeo)
4036 * XXX This is here until the sleep path is diagnosed
4037 * enough to work under very low memory conditions.
4039 * There's an issue on low memory, 4BSD+non-preempt
4040 * systems (eg MIPS routers with 32MB RAM) where buffer
4041 * exhaustion occurs without sleeping for buffer
4042 * reclaimation. This just sticks in a loop and
4043 * constantly attempts to allocate a buffer, which
4044 * hits exhaustion and tries to wakeup bufdaemon.
4045 * This never happens because we never yield.
4047 * The real solution is to identify and fix these cases
4048 * so we aren't effectively busy-waiting in a loop
4049 * until the reclaimation path has cycles to run.
4051 kern_yield(PRI_USER);
4056 * This code is used to make sure that a buffer is not
4057 * created while the getnewbuf routine is blocked.
4058 * This can be a problem whether the vnode is locked or not.
4059 * If the buffer is created out from under us, we have to
4060 * throw away the one we just created.
4062 * Note: this must occur before we associate the buffer
4063 * with the vp especially considering limitations in
4064 * the splay tree implementation when dealing with duplicate
4068 if (gbincore(bo, blkno)) {
4070 bp->b_flags |= B_INVAL;
4071 bufspace_release(bufdomain(bp), maxsize);
4077 * Insert the buffer into the hash, so that it can
4078 * be found by incore.
4080 bp->b_lblkno = blkno;
4081 bp->b_blkno = d_blkno;
4082 bp->b_offset = offset;
4087 * set B_VMIO bit. allocbuf() the buffer bigger. Since the
4088 * buffer size starts out as 0, B_CACHE will be set by
4089 * allocbuf() for the VMIO case prior to it testing the
4090 * backing store for validity.
4094 bp->b_flags |= B_VMIO;
4095 KASSERT(vp->v_object == bp->b_bufobj->bo_object,
4096 ("ARGH! different b_bufobj->bo_object %p %p %p\n",
4097 bp, vp->v_object, bp->b_bufobj->bo_object));
4099 bp->b_flags &= ~B_VMIO;
4100 KASSERT(bp->b_bufobj->bo_object == NULL,
4101 ("ARGH! has b_bufobj->bo_object %p %p\n",
4102 bp, bp->b_bufobj->bo_object));
4103 BUF_CHECK_MAPPED(bp);
4107 bufspace_release(bufdomain(bp), maxsize);
4108 bp->b_flags &= ~B_DONE;
4110 CTR4(KTR_BUF, "getblk(%p, %ld, %d) = %p", vp, (long)blkno, size, bp);
4112 buf_track(bp, __func__);
4113 KASSERT(bp->b_bufobj == bo,
4114 ("bp %p wrong b_bufobj %p should be %p", bp, bp->b_bufobj, bo));
4120 * Get an empty, disassociated buffer of given size. The buffer is initially
4124 geteblk(int size, int flags)
4129 maxsize = (size + BKVAMASK) & ~BKVAMASK;
4130 while ((bp = getnewbuf(NULL, 0, 0, maxsize, flags)) == NULL) {
4131 if ((flags & GB_NOWAIT_BD) &&
4132 (curthread->td_pflags & TDP_BUFNEED) != 0)
4136 bufspace_release(bufdomain(bp), maxsize);
4137 bp->b_flags |= B_INVAL; /* b_dep cleared by getnewbuf() */
4142 * Truncate the backing store for a non-vmio buffer.
4145 vfs_nonvmio_truncate(struct buf *bp, int newbsize)
4148 if (bp->b_flags & B_MALLOC) {
4150 * malloced buffers are not shrunk
4152 if (newbsize == 0) {
4153 bufmallocadjust(bp, 0);
4154 free(bp->b_data, M_BIOBUF);
4155 bp->b_data = bp->b_kvabase;
4156 bp->b_flags &= ~B_MALLOC;
4160 vm_hold_free_pages(bp, newbsize);
4161 bufspace_adjust(bp, newbsize);
4165 * Extend the backing for a non-VMIO buffer.
4168 vfs_nonvmio_extend(struct buf *bp, int newbsize)
4174 * We only use malloced memory on the first allocation.
4175 * and revert to page-allocated memory when the buffer
4178 * There is a potential smp race here that could lead
4179 * to bufmallocspace slightly passing the max. It
4180 * is probably extremely rare and not worth worrying
4183 if (bp->b_bufsize == 0 && newbsize <= PAGE_SIZE/2 &&
4184 bufmallocspace < maxbufmallocspace) {
4185 bp->b_data = malloc(newbsize, M_BIOBUF, M_WAITOK);
4186 bp->b_flags |= B_MALLOC;
4187 bufmallocadjust(bp, newbsize);
4192 * If the buffer is growing on its other-than-first
4193 * allocation then we revert to the page-allocation
4198 if (bp->b_flags & B_MALLOC) {
4199 origbuf = bp->b_data;
4200 origbufsize = bp->b_bufsize;
4201 bp->b_data = bp->b_kvabase;
4202 bufmallocadjust(bp, 0);
4203 bp->b_flags &= ~B_MALLOC;
4204 newbsize = round_page(newbsize);
4206 vm_hold_load_pages(bp, (vm_offset_t) bp->b_data + bp->b_bufsize,
4207 (vm_offset_t) bp->b_data + newbsize);
4208 if (origbuf != NULL) {
4209 bcopy(origbuf, bp->b_data, origbufsize);
4210 free(origbuf, M_BIOBUF);
4212 bufspace_adjust(bp, newbsize);
4216 * This code constitutes the buffer memory from either anonymous system
4217 * memory (in the case of non-VMIO operations) or from an associated
4218 * VM object (in the case of VMIO operations). This code is able to
4219 * resize a buffer up or down.
4221 * Note that this code is tricky, and has many complications to resolve
4222 * deadlock or inconsistent data situations. Tread lightly!!!
4223 * There are B_CACHE and B_DELWRI interactions that must be dealt with by
4224 * the caller. Calling this code willy nilly can result in the loss of data.
4226 * allocbuf() only adjusts B_CACHE for VMIO buffers. getblk() deals with
4227 * B_CACHE for the non-VMIO case.
4230 allocbuf(struct buf *bp, int size)
4234 if (bp->b_bcount == size)
4237 if (bp->b_kvasize != 0 && bp->b_kvasize < size)
4238 panic("allocbuf: buffer too small");
4240 newbsize = roundup2(size, DEV_BSIZE);
4241 if ((bp->b_flags & B_VMIO) == 0) {
4242 if ((bp->b_flags & B_MALLOC) == 0)
4243 newbsize = round_page(newbsize);
4245 * Just get anonymous memory from the kernel. Don't
4246 * mess with B_CACHE.
4248 if (newbsize < bp->b_bufsize)
4249 vfs_nonvmio_truncate(bp, newbsize);
4250 else if (newbsize > bp->b_bufsize)
4251 vfs_nonvmio_extend(bp, newbsize);
4255 desiredpages = (size == 0) ? 0 :
4256 num_pages((bp->b_offset & PAGE_MASK) + newbsize);
4258 if (bp->b_flags & B_MALLOC)
4259 panic("allocbuf: VMIO buffer can't be malloced");
4261 * Set B_CACHE initially if buffer is 0 length or will become
4264 if (size == 0 || bp->b_bufsize == 0)
4265 bp->b_flags |= B_CACHE;
4267 if (newbsize < bp->b_bufsize)
4268 vfs_vmio_truncate(bp, desiredpages);
4269 /* XXX This looks as if it should be newbsize > b_bufsize */
4270 else if (size > bp->b_bcount)
4271 vfs_vmio_extend(bp, desiredpages, size);
4272 bufspace_adjust(bp, newbsize);
4274 bp->b_bcount = size; /* requested buffer size. */
4278 extern int inflight_transient_maps;
4280 static struct bio_queue nondump_bios;
4283 biodone(struct bio *bp)
4286 void (*done)(struct bio *);
4287 vm_offset_t start, end;
4289 biotrack(bp, __func__);
4292 * Avoid completing I/O when dumping after a panic since that may
4293 * result in a deadlock in the filesystem or pager code. Note that
4294 * this doesn't affect dumps that were started manually since we aim
4295 * to keep the system usable after it has been resumed.
4297 if (__predict_false(dumping && SCHEDULER_STOPPED())) {
4298 TAILQ_INSERT_HEAD(&nondump_bios, bp, bio_queue);
4301 if ((bp->bio_flags & BIO_TRANSIENT_MAPPING) != 0) {
4302 bp->bio_flags &= ~BIO_TRANSIENT_MAPPING;
4303 bp->bio_flags |= BIO_UNMAPPED;
4304 start = trunc_page((vm_offset_t)bp->bio_data);
4305 end = round_page((vm_offset_t)bp->bio_data + bp->bio_length);
4306 bp->bio_data = unmapped_buf;
4307 pmap_qremove(start, atop(end - start));
4308 vmem_free(transient_arena, start, end - start);
4309 atomic_add_int(&inflight_transient_maps, -1);
4311 done = bp->bio_done;
4313 mtxp = mtx_pool_find(mtxpool_sleep, bp);
4315 bp->bio_flags |= BIO_DONE;
4323 * Wait for a BIO to finish.
4326 biowait(struct bio *bp, const char *wchan)
4330 mtxp = mtx_pool_find(mtxpool_sleep, bp);
4332 while ((bp->bio_flags & BIO_DONE) == 0)
4333 msleep(bp, mtxp, PRIBIO, wchan, 0);
4335 if (bp->bio_error != 0)
4336 return (bp->bio_error);
4337 if (!(bp->bio_flags & BIO_ERROR))
4343 biofinish(struct bio *bp, struct devstat *stat, int error)
4347 bp->bio_error = error;
4348 bp->bio_flags |= BIO_ERROR;
4351 devstat_end_transaction_bio(stat, bp);
4355 #if defined(BUF_TRACKING) || defined(FULL_BUF_TRACKING)
4357 biotrack_buf(struct bio *bp, const char *location)
4360 buf_track(bp->bio_track_bp, location);
4367 * Wait for buffer I/O completion, returning error status. The buffer
4368 * is left locked and B_DONE on return. B_EINTR is converted into an EINTR
4369 * error and cleared.
4372 bufwait(struct buf *bp)
4374 if (bp->b_iocmd == BIO_READ)
4375 bwait(bp, PRIBIO, "biord");
4377 bwait(bp, PRIBIO, "biowr");
4378 if (bp->b_flags & B_EINTR) {
4379 bp->b_flags &= ~B_EINTR;
4382 if (bp->b_ioflags & BIO_ERROR) {
4383 return (bp->b_error ? bp->b_error : EIO);
4392 * Finish I/O on a buffer, optionally calling a completion function.
4393 * This is usually called from an interrupt so process blocking is
4396 * biodone is also responsible for setting B_CACHE in a B_VMIO bp.
4397 * In a non-VMIO bp, B_CACHE will be set on the next getblk()
4398 * assuming B_INVAL is clear.
4400 * For the VMIO case, we set B_CACHE if the op was a read and no
4401 * read error occurred, or if the op was a write. B_CACHE is never
4402 * set if the buffer is invalid or otherwise uncacheable.
4404 * bufdone does not mess with B_INVAL, allowing the I/O routine or the
4405 * initiator to leave B_INVAL set to brelse the buffer out of existence
4406 * in the biodone routine.
4409 bufdone(struct buf *bp)
4411 struct bufobj *dropobj;
4412 void (*biodone)(struct buf *);
4414 buf_track(bp, __func__);
4415 CTR3(KTR_BUF, "bufdone(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
4418 KASSERT(!(bp->b_flags & B_DONE), ("biodone: bp %p already done", bp));
4420 runningbufwakeup(bp);
4421 if (bp->b_iocmd == BIO_WRITE)
4422 dropobj = bp->b_bufobj;
4423 /* call optional completion function if requested */
4424 if (bp->b_iodone != NULL) {
4425 biodone = bp->b_iodone;
4426 bp->b_iodone = NULL;
4429 bufobj_wdrop(dropobj);
4432 if (bp->b_flags & B_VMIO) {
4434 * Set B_CACHE if the op was a normal read and no error
4435 * occurred. B_CACHE is set for writes in the b*write()
4438 if (bp->b_iocmd == BIO_READ &&
4439 !(bp->b_flags & (B_INVAL|B_NOCACHE)) &&
4440 !(bp->b_ioflags & BIO_ERROR))
4441 bp->b_flags |= B_CACHE;
4442 vfs_vmio_iodone(bp);
4444 if (!LIST_EMPTY(&bp->b_dep))
4446 if ((bp->b_flags & B_CKHASH) != 0) {
4447 KASSERT(bp->b_iocmd == BIO_READ,
4448 ("bufdone: b_iocmd %d not BIO_READ", bp->b_iocmd));
4449 KASSERT(buf_mapped(bp), ("bufdone: bp %p not mapped", bp));
4450 (*bp->b_ckhashcalc)(bp);
4453 * For asynchronous completions, release the buffer now. The brelse
4454 * will do a wakeup there if necessary - so no need to do a wakeup
4455 * here in the async case. The sync case always needs to do a wakeup.
4457 if (bp->b_flags & B_ASYNC) {
4458 if ((bp->b_flags & (B_NOCACHE | B_INVAL | B_RELBUF)) ||
4459 (bp->b_ioflags & BIO_ERROR))
4466 bufobj_wdrop(dropobj);
4470 * This routine is called in lieu of iodone in the case of
4471 * incomplete I/O. This keeps the busy status for pages
4475 vfs_unbusy_pages(struct buf *bp)
4482 runningbufwakeup(bp);
4483 if (!(bp->b_flags & B_VMIO))
4486 obj = bp->b_bufobj->bo_object;
4488 for (i = 0; i < bp->b_npages; i++) {
4490 if (m == bogus_page) {
4491 if (bogus == false) {
4493 VM_OBJECT_RLOCK(obj);
4495 m = vm_page_lookup(obj, OFF_TO_IDX(bp->b_offset) + i);
4497 panic("vfs_unbusy_pages: page missing\n");
4499 if (buf_mapped(bp)) {
4500 BUF_CHECK_MAPPED(bp);
4501 pmap_qenter(trunc_page((vm_offset_t)bp->b_data),
4502 bp->b_pages, bp->b_npages);
4504 BUF_CHECK_UNMAPPED(bp);
4509 VM_OBJECT_RUNLOCK(obj);
4510 vm_object_pip_wakeupn(obj, bp->b_npages);
4514 * vfs_page_set_valid:
4516 * Set the valid bits in a page based on the supplied offset. The
4517 * range is restricted to the buffer's size.
4519 * This routine is typically called after a read completes.
4522 vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, vm_page_t m)
4527 * Compute the end offset, eoff, such that [off, eoff) does not span a
4528 * page boundary and eoff is not greater than the end of the buffer.
4529 * The end of the buffer, in this case, is our file EOF, not the
4530 * allocation size of the buffer.
4532 eoff = (off + PAGE_SIZE) & ~(vm_ooffset_t)PAGE_MASK;
4533 if (eoff > bp->b_offset + bp->b_bcount)
4534 eoff = bp->b_offset + bp->b_bcount;
4537 * Set valid range. This is typically the entire buffer and thus the
4541 vm_page_set_valid_range(m, off & PAGE_MASK, eoff - off);
4545 * vfs_page_set_validclean:
4547 * Set the valid bits and clear the dirty bits in a page based on the
4548 * supplied offset. The range is restricted to the buffer's size.
4551 vfs_page_set_validclean(struct buf *bp, vm_ooffset_t off, vm_page_t m)
4553 vm_ooffset_t soff, eoff;
4556 * Start and end offsets in buffer. eoff - soff may not cross a
4557 * page boundary or cross the end of the buffer. The end of the
4558 * buffer, in this case, is our file EOF, not the allocation size
4562 eoff = (off + PAGE_SIZE) & ~(off_t)PAGE_MASK;
4563 if (eoff > bp->b_offset + bp->b_bcount)
4564 eoff = bp->b_offset + bp->b_bcount;
4567 * Set valid range. This is typically the entire buffer and thus the
4571 vm_page_set_validclean(
4573 (vm_offset_t) (soff & PAGE_MASK),
4574 (vm_offset_t) (eoff - soff)
4580 * Acquire a shared busy on all pages in the buf.
4583 vfs_busy_pages_acquire(struct buf *bp)
4587 for (i = 0; i < bp->b_npages; i++)
4588 vm_page_busy_acquire(bp->b_pages[i], VM_ALLOC_SBUSY);
4592 vfs_busy_pages_release(struct buf *bp)
4596 for (i = 0; i < bp->b_npages; i++)
4597 vm_page_sunbusy(bp->b_pages[i]);
4601 * This routine is called before a device strategy routine.
4602 * It is used to tell the VM system that paging I/O is in
4603 * progress, and treat the pages associated with the buffer
4604 * almost as being exclusive busy. Also the object paging_in_progress
4605 * flag is handled to make sure that the object doesn't become
4608 * Since I/O has not been initiated yet, certain buffer flags
4609 * such as BIO_ERROR or B_INVAL may be in an inconsistent state
4610 * and should be ignored.
4613 vfs_busy_pages(struct buf *bp, int clear_modify)
4621 if (!(bp->b_flags & B_VMIO))
4624 obj = bp->b_bufobj->bo_object;
4625 foff = bp->b_offset;
4626 KASSERT(bp->b_offset != NOOFFSET,
4627 ("vfs_busy_pages: no buffer offset"));
4628 if ((bp->b_flags & B_CLUSTER) == 0) {
4629 vm_object_pip_add(obj, bp->b_npages);
4630 vfs_busy_pages_acquire(bp);
4632 if (bp->b_bufsize != 0)
4633 vfs_setdirty_range(bp);
4635 for (i = 0; i < bp->b_npages; i++) {
4637 vm_page_assert_sbusied(m);
4640 * When readying a buffer for a read ( i.e
4641 * clear_modify == 0 ), it is important to do
4642 * bogus_page replacement for valid pages in
4643 * partially instantiated buffers. Partially
4644 * instantiated buffers can, in turn, occur when
4645 * reconstituting a buffer from its VM backing store
4646 * base. We only have to do this if B_CACHE is
4647 * clear ( which causes the I/O to occur in the
4648 * first place ). The replacement prevents the read
4649 * I/O from overwriting potentially dirty VM-backed
4650 * pages. XXX bogus page replacement is, uh, bogus.
4651 * It may not work properly with small-block devices.
4652 * We need to find a better way.
4655 pmap_remove_write(m);
4656 vfs_page_set_validclean(bp, foff, m);
4657 } else if (vm_page_all_valid(m) &&
4658 (bp->b_flags & B_CACHE) == 0) {
4659 bp->b_pages[i] = bogus_page;
4662 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK;
4664 if (bogus && buf_mapped(bp)) {
4665 BUF_CHECK_MAPPED(bp);
4666 pmap_qenter(trunc_page((vm_offset_t)bp->b_data),
4667 bp->b_pages, bp->b_npages);
4672 * vfs_bio_set_valid:
4674 * Set the range within the buffer to valid. The range is
4675 * relative to the beginning of the buffer, b_offset. Note that
4676 * b_offset itself may be offset from the beginning of the first
4680 vfs_bio_set_valid(struct buf *bp, int base, int size)
4685 if (!(bp->b_flags & B_VMIO))
4689 * Fixup base to be relative to beginning of first page.
4690 * Set initial n to be the maximum number of bytes in the
4691 * first page that can be validated.
4693 base += (bp->b_offset & PAGE_MASK);
4694 n = PAGE_SIZE - (base & PAGE_MASK);
4697 * Busy may not be strictly necessary here because the pages are
4698 * unlikely to be fully valid and the vnode lock will synchronize
4699 * their access via getpages. It is grabbed for consistency with
4700 * other page validation.
4702 vfs_busy_pages_acquire(bp);
4703 for (i = base / PAGE_SIZE; size > 0 && i < bp->b_npages; ++i) {
4707 vm_page_set_valid_range(m, base & PAGE_MASK, n);
4712 vfs_busy_pages_release(bp);
4718 * If the specified buffer is a non-VMIO buffer, clear the entire
4719 * buffer. If the specified buffer is a VMIO buffer, clear and
4720 * validate only the previously invalid portions of the buffer.
4721 * This routine essentially fakes an I/O, so we need to clear
4722 * BIO_ERROR and B_INVAL.
4724 * Note that while we only theoretically need to clear through b_bcount,
4725 * we go ahead and clear through b_bufsize.
4728 vfs_bio_clrbuf(struct buf *bp)
4730 int i, j, mask, sa, ea, slide;
4732 if ((bp->b_flags & (B_VMIO | B_MALLOC)) != B_VMIO) {
4736 bp->b_flags &= ~B_INVAL;
4737 bp->b_ioflags &= ~BIO_ERROR;
4738 vfs_busy_pages_acquire(bp);
4739 sa = bp->b_offset & PAGE_MASK;
4741 for (i = 0; i < bp->b_npages; i++, sa = 0) {
4742 slide = imin(slide + PAGE_SIZE, bp->b_offset + bp->b_bufsize);
4743 ea = slide & PAGE_MASK;
4746 if (bp->b_pages[i] == bogus_page)
4749 mask = ((1 << ((ea - sa) / DEV_BSIZE)) - 1) << j;
4750 if ((bp->b_pages[i]->valid & mask) == mask)
4752 if ((bp->b_pages[i]->valid & mask) == 0)
4753 pmap_zero_page_area(bp->b_pages[i], sa, ea - sa);
4755 for (; sa < ea; sa += DEV_BSIZE, j++) {
4756 if ((bp->b_pages[i]->valid & (1 << j)) == 0) {
4757 pmap_zero_page_area(bp->b_pages[i],
4762 vm_page_set_valid_range(bp->b_pages[i], j * DEV_BSIZE,
4763 roundup2(ea - sa, DEV_BSIZE));
4765 vfs_busy_pages_release(bp);
4770 vfs_bio_bzero_buf(struct buf *bp, int base, int size)
4775 if (buf_mapped(bp)) {
4776 BUF_CHECK_MAPPED(bp);
4777 bzero(bp->b_data + base, size);
4779 BUF_CHECK_UNMAPPED(bp);
4780 n = PAGE_SIZE - (base & PAGE_MASK);
4781 for (i = base / PAGE_SIZE; size > 0 && i < bp->b_npages; ++i) {
4785 pmap_zero_page_area(m, base & PAGE_MASK, n);
4794 * Update buffer flags based on I/O request parameters, optionally releasing the
4795 * buffer. If it's VMIO or direct I/O, the buffer pages are released to the VM,
4796 * where they may be placed on a page queue (VMIO) or freed immediately (direct
4797 * I/O). Otherwise the buffer is released to the cache.
4800 b_io_dismiss(struct buf *bp, int ioflag, bool release)
4803 KASSERT((ioflag & IO_NOREUSE) == 0 || (ioflag & IO_VMIO) != 0,
4804 ("buf %p non-VMIO noreuse", bp));
4806 if ((ioflag & IO_DIRECT) != 0)
4807 bp->b_flags |= B_DIRECT;
4808 if ((ioflag & IO_EXT) != 0)
4809 bp->b_xflags |= BX_ALTDATA;
4810 if ((ioflag & (IO_VMIO | IO_DIRECT)) != 0 && LIST_EMPTY(&bp->b_dep)) {
4811 bp->b_flags |= B_RELBUF;
4812 if ((ioflag & IO_NOREUSE) != 0)
4813 bp->b_flags |= B_NOREUSE;
4821 vfs_bio_brelse(struct buf *bp, int ioflag)
4824 b_io_dismiss(bp, ioflag, true);
4828 vfs_bio_set_flags(struct buf *bp, int ioflag)
4831 b_io_dismiss(bp, ioflag, false);
4835 * vm_hold_load_pages and vm_hold_free_pages get pages into
4836 * a buffers address space. The pages are anonymous and are
4837 * not associated with a file object.
4840 vm_hold_load_pages(struct buf *bp, vm_offset_t from, vm_offset_t to)
4846 BUF_CHECK_MAPPED(bp);
4848 to = round_page(to);
4849 from = round_page(from);
4850 index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT;
4852 for (pg = from; pg < to; pg += PAGE_SIZE, index++) {
4854 * note: must allocate system pages since blocking here
4855 * could interfere with paging I/O, no matter which
4858 p = vm_page_alloc(NULL, 0, VM_ALLOC_SYSTEM | VM_ALLOC_NOOBJ |
4859 VM_ALLOC_WIRED | VM_ALLOC_COUNT((to - pg) >> PAGE_SHIFT) |
4861 pmap_qenter(pg, &p, 1);
4862 bp->b_pages[index] = p;
4864 bp->b_npages = index;
4867 /* Return pages associated with this buf to the vm system */
4869 vm_hold_free_pages(struct buf *bp, int newbsize)
4873 int index, newnpages;
4875 BUF_CHECK_MAPPED(bp);
4877 from = round_page((vm_offset_t)bp->b_data + newbsize);
4878 newnpages = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT;
4879 if (bp->b_npages > newnpages)
4880 pmap_qremove(from, bp->b_npages - newnpages);
4881 for (index = newnpages; index < bp->b_npages; index++) {
4882 p = bp->b_pages[index];
4883 bp->b_pages[index] = NULL;
4884 vm_page_unwire_noq(p);
4887 bp->b_npages = newnpages;
4891 * Map an IO request into kernel virtual address space.
4893 * All requests are (re)mapped into kernel VA space.
4894 * Notice that we use b_bufsize for the size of the buffer
4895 * to be mapped. b_bcount might be modified by the driver.
4897 * Note that even if the caller determines that the address space should
4898 * be valid, a race or a smaller-file mapped into a larger space may
4899 * actually cause vmapbuf() to fail, so all callers of vmapbuf() MUST
4900 * check the return value.
4902 * This function only works with pager buffers.
4905 vmapbuf(struct buf *bp, int mapbuf)
4910 if (bp->b_bufsize < 0)
4912 prot = VM_PROT_READ;
4913 if (bp->b_iocmd == BIO_READ)
4914 prot |= VM_PROT_WRITE; /* Less backwards than it looks */
4915 if ((pidx = vm_fault_quick_hold_pages(&curproc->p_vmspace->vm_map,
4916 (vm_offset_t)bp->b_data, bp->b_bufsize, prot, bp->b_pages,
4917 btoc(MAXPHYS))) < 0)
4919 bp->b_npages = pidx;
4920 bp->b_offset = ((vm_offset_t)bp->b_data) & PAGE_MASK;
4921 if (mapbuf || !unmapped_buf_allowed) {
4922 pmap_qenter((vm_offset_t)bp->b_kvabase, bp->b_pages, pidx);
4923 bp->b_data = bp->b_kvabase + bp->b_offset;
4925 bp->b_data = unmapped_buf;
4930 * Free the io map PTEs associated with this IO operation.
4931 * We also invalidate the TLB entries and restore the original b_addr.
4933 * This function only works with pager buffers.
4936 vunmapbuf(struct buf *bp)
4940 npages = bp->b_npages;
4942 pmap_qremove(trunc_page((vm_offset_t)bp->b_data), npages);
4943 vm_page_unhold_pages(bp->b_pages, npages);
4945 bp->b_data = unmapped_buf;
4949 bdone(struct buf *bp)
4953 mtxp = mtx_pool_find(mtxpool_sleep, bp);
4955 bp->b_flags |= B_DONE;
4961 bwait(struct buf *bp, u_char pri, const char *wchan)
4965 mtxp = mtx_pool_find(mtxpool_sleep, bp);
4967 while ((bp->b_flags & B_DONE) == 0)
4968 msleep(bp, mtxp, pri, wchan, 0);
4973 bufsync(struct bufobj *bo, int waitfor)
4976 return (VOP_FSYNC(bo2vnode(bo), waitfor, curthread));
4980 bufstrategy(struct bufobj *bo, struct buf *bp)
4986 KASSERT(vp == bo->bo_private, ("Inconsistent vnode bufstrategy"));
4987 KASSERT(vp->v_type != VCHR && vp->v_type != VBLK,
4988 ("Wrong vnode in bufstrategy(bp=%p, vp=%p)", bp, vp));
4989 i = VOP_STRATEGY(vp, bp);
4990 KASSERT(i == 0, ("VOP_STRATEGY failed bp=%p vp=%p", bp, bp->b_vp));
4994 * Initialize a struct bufobj before use. Memory is assumed zero filled.
4997 bufobj_init(struct bufobj *bo, void *private)
4999 static volatile int bufobj_cleanq;
5002 atomic_fetchadd_int(&bufobj_cleanq, 1) % buf_domains;
5003 rw_init(BO_LOCKPTR(bo), "bufobj interlock");
5004 bo->bo_private = private;
5005 TAILQ_INIT(&bo->bo_clean.bv_hd);
5006 TAILQ_INIT(&bo->bo_dirty.bv_hd);
5010 bufobj_wrefl(struct bufobj *bo)
5013 KASSERT(bo != NULL, ("NULL bo in bufobj_wref"));
5014 ASSERT_BO_WLOCKED(bo);
5019 bufobj_wref(struct bufobj *bo)
5022 KASSERT(bo != NULL, ("NULL bo in bufobj_wref"));
5029 bufobj_wdrop(struct bufobj *bo)
5032 KASSERT(bo != NULL, ("NULL bo in bufobj_wdrop"));
5034 KASSERT(bo->bo_numoutput > 0, ("bufobj_wdrop non-positive count"));
5035 if ((--bo->bo_numoutput == 0) && (bo->bo_flag & BO_WWAIT)) {
5036 bo->bo_flag &= ~BO_WWAIT;
5037 wakeup(&bo->bo_numoutput);
5043 bufobj_wwait(struct bufobj *bo, int slpflag, int timeo)
5047 KASSERT(bo != NULL, ("NULL bo in bufobj_wwait"));
5048 ASSERT_BO_WLOCKED(bo);
5050 while (bo->bo_numoutput) {
5051 bo->bo_flag |= BO_WWAIT;
5052 error = msleep(&bo->bo_numoutput, BO_LOCKPTR(bo),
5053 slpflag | (PRIBIO + 1), "bo_wwait", timeo);
5061 * Set bio_data or bio_ma for struct bio from the struct buf.
5064 bdata2bio(struct buf *bp, struct bio *bip)
5067 if (!buf_mapped(bp)) {
5068 KASSERT(unmapped_buf_allowed, ("unmapped"));
5069 bip->bio_ma = bp->b_pages;
5070 bip->bio_ma_n = bp->b_npages;
5071 bip->bio_data = unmapped_buf;
5072 bip->bio_ma_offset = (vm_offset_t)bp->b_offset & PAGE_MASK;
5073 bip->bio_flags |= BIO_UNMAPPED;
5074 KASSERT(round_page(bip->bio_ma_offset + bip->bio_length) /
5075 PAGE_SIZE == bp->b_npages,
5076 ("Buffer %p too short: %d %lld %d", bp, bip->bio_ma_offset,
5077 (long long)bip->bio_length, bip->bio_ma_n));
5079 bip->bio_data = bp->b_data;
5085 * The MIPS pmap code currently doesn't handle aliased pages.
5086 * The VIPT caches may not handle page aliasing themselves, leading
5087 * to data corruption.
5089 * As such, this code makes a system extremely unhappy if said
5090 * system doesn't support unaliasing the above situation in hardware.
5091 * Some "recent" systems (eg some mips24k/mips74k cores) don't enable
5092 * this feature at build time, so it has to be handled in software.
5094 * Once the MIPS pmap/cache code grows to support this function on
5095 * earlier chips, it should be flipped back off.
5098 static int buf_pager_relbuf = 1;
5100 static int buf_pager_relbuf = 0;
5102 SYSCTL_INT(_vfs, OID_AUTO, buf_pager_relbuf, CTLFLAG_RWTUN,
5103 &buf_pager_relbuf, 0,
5104 "Make buffer pager release buffers after reading");
5107 * The buffer pager. It uses buffer reads to validate pages.
5109 * In contrast to the generic local pager from vm/vnode_pager.c, this
5110 * pager correctly and easily handles volumes where the underlying
5111 * device block size is greater than the machine page size. The
5112 * buffer cache transparently extends the requested page run to be
5113 * aligned at the block boundary, and does the necessary bogus page
5114 * replacements in the addends to avoid obliterating already valid
5117 * The only non-trivial issue is that the exclusive busy state for
5118 * pages, which is assumed by the vm_pager_getpages() interface, is
5119 * incompatible with the VMIO buffer cache's desire to share-busy the
5120 * pages. This function performs a trivial downgrade of the pages'
5121 * state before reading buffers, and a less trivial upgrade from the
5122 * shared-busy to excl-busy state after the read.
5125 vfs_bio_getpages(struct vnode *vp, vm_page_t *ma, int count,
5126 int *rbehind, int *rahead, vbg_get_lblkno_t get_lblkno,
5127 vbg_get_blksize_t get_blksize)
5134 vm_ooffset_t la, lb, poff, poffe;
5136 int bo_bs, br_flags, error, i, pgsin, pgsin_a, pgsin_b;
5139 object = vp->v_object;
5142 la = IDX_TO_OFF(ma[count - 1]->pindex);
5143 if (la >= object->un_pager.vnp.vnp_size)
5144 return (VM_PAGER_BAD);
5147 * Change the meaning of la from where the last requested page starts
5148 * to where it ends, because that's the end of the requested region
5149 * and the start of the potential read-ahead region.
5152 lpart = la > object->un_pager.vnp.vnp_size;
5153 bo_bs = get_blksize(vp, get_lblkno(vp, IDX_TO_OFF(ma[0]->pindex)));
5156 * Calculate read-ahead, behind and total pages.
5159 lb = IDX_TO_OFF(ma[0]->pindex);
5160 pgsin_b = OFF_TO_IDX(lb - rounddown2(lb, bo_bs));
5162 if (rbehind != NULL)
5164 pgsin_a = OFF_TO_IDX(roundup2(la, bo_bs) - la);
5165 if (la + IDX_TO_OFF(pgsin_a) >= object->un_pager.vnp.vnp_size)
5166 pgsin_a = OFF_TO_IDX(roundup2(object->un_pager.vnp.vnp_size,
5171 VM_CNT_INC(v_vnodein);
5172 VM_CNT_ADD(v_vnodepgsin, pgsin);
5174 br_flags = (mp != NULL && (mp->mnt_kern_flag & MNTK_UNMAPPED_BUFS)
5175 != 0) ? GB_UNMAPPED : 0;
5177 for (i = 0; i < count; i++)
5178 vm_page_busy_downgrade(ma[i]);
5181 for (i = 0; i < count; i++) {
5185 * Pages are shared busy and the object lock is not
5186 * owned, which together allow for the pages'
5187 * invalidation. The racy test for validity avoids
5188 * useless creation of the buffer for the most typical
5189 * case when invalidation is not used in redo or for
5190 * parallel read. The shared->excl upgrade loop at
5191 * the end of the function catches the race in a
5192 * reliable way (protected by the object lock).
5194 if (vm_page_all_valid(m))
5197 poff = IDX_TO_OFF(m->pindex);
5198 poffe = MIN(poff + PAGE_SIZE, object->un_pager.vnp.vnp_size);
5199 for (; poff < poffe; poff += bsize) {
5200 lbn = get_lblkno(vp, poff);
5205 bsize = get_blksize(vp, lbn);
5206 error = bread_gb(vp, lbn, bsize, curthread->td_ucred,
5210 if (LIST_EMPTY(&bp->b_dep)) {
5212 * Invalidation clears m->valid, but
5213 * may leave B_CACHE flag if the
5214 * buffer existed at the invalidation
5215 * time. In this case, recycle the
5216 * buffer to do real read on next
5217 * bread() after redo.
5219 * Otherwise B_RELBUF is not strictly
5220 * necessary, enable to reduce buf
5223 if (buf_pager_relbuf ||
5224 !vm_page_all_valid(m))
5225 bp->b_flags |= B_RELBUF;
5227 bp->b_flags &= ~B_NOCACHE;
5233 KASSERT(1 /* racy, enable for debugging */ ||
5234 vm_page_all_valid(m) || i == count - 1,
5235 ("buf %d %p invalid", i, m));
5236 if (i == count - 1 && lpart) {
5237 if (!vm_page_none_valid(m) &&
5238 !vm_page_all_valid(m))
5239 vm_page_zero_invalid(m, TRUE);
5245 VM_OBJECT_WLOCK(object);
5247 for (i = 0; i < count; i++) {
5248 vm_page_sunbusy(ma[i]);
5249 ma[i] = vm_page_grab(object, ma[i]->pindex, VM_ALLOC_NORMAL);
5252 * Since the pages were only sbusy while neither the
5253 * buffer nor the object lock was held by us, or
5254 * reallocated while vm_page_grab() slept for busy
5255 * relinguish, they could have been invalidated.
5256 * Recheck the valid bits and re-read as needed.
5258 * Note that the last page is made fully valid in the
5259 * read loop, and partial validity for the page at
5260 * index count - 1 could mean that the page was
5261 * invalidated or removed, so we must restart for
5264 if (!vm_page_all_valid(ma[i]))
5267 VM_OBJECT_WUNLOCK(object);
5268 if (redo && error == 0)
5270 return (error != 0 ? VM_PAGER_ERROR : VM_PAGER_OK);
5273 #include "opt_ddb.h"
5275 #include <ddb/ddb.h>
5277 /* DDB command to show buffer data */
5278 DB_SHOW_COMMAND(buffer, db_show_buffer)
5281 struct buf *bp = (struct buf *)addr;
5282 #ifdef FULL_BUF_TRACKING
5287 db_printf("usage: show buffer <addr>\n");
5291 db_printf("buf at %p\n", bp);
5292 db_printf("b_flags = 0x%b, b_xflags=0x%b\n",
5293 (u_int)bp->b_flags, PRINT_BUF_FLAGS,
5294 (u_int)bp->b_xflags, PRINT_BUF_XFLAGS);
5295 db_printf("b_vflags=0x%b b_ioflags0x%b\n",
5296 (u_int)bp->b_vflags, PRINT_BUF_VFLAGS,
5297 (u_int)bp->b_ioflags, PRINT_BIO_FLAGS);
5299 "b_error = %d, b_bufsize = %ld, b_bcount = %ld, b_resid = %ld\n"
5300 "b_bufobj = (%p), b_data = %p\n, b_blkno = %jd, b_lblkno = %jd, "
5301 "b_vp = %p, b_dep = %p\n",
5302 bp->b_error, bp->b_bufsize, bp->b_bcount, bp->b_resid,
5303 bp->b_bufobj, bp->b_data, (intmax_t)bp->b_blkno,
5304 (intmax_t)bp->b_lblkno, bp->b_vp, bp->b_dep.lh_first);
5305 db_printf("b_kvabase = %p, b_kvasize = %d\n",
5306 bp->b_kvabase, bp->b_kvasize);
5309 db_printf("b_npages = %d, pages(OBJ, IDX, PA): ", bp->b_npages);
5310 for (i = 0; i < bp->b_npages; i++) {
5314 db_printf("(%p, 0x%lx, 0x%lx)", m->object,
5316 (u_long)VM_PAGE_TO_PHYS(m));
5318 db_printf("( ??? )");
5319 if ((i + 1) < bp->b_npages)
5324 BUF_LOCKPRINTINFO(bp);
5325 #if defined(FULL_BUF_TRACKING)
5326 db_printf("b_io_tracking: b_io_tcnt = %u\n", bp->b_io_tcnt);
5328 i = bp->b_io_tcnt % BUF_TRACKING_SIZE;
5329 for (j = 1; j <= BUF_TRACKING_SIZE; j++) {
5330 if (bp->b_io_tracking[BUF_TRACKING_ENTRY(i - j)] == NULL)
5332 db_printf(" %2u: %s\n", j,
5333 bp->b_io_tracking[BUF_TRACKING_ENTRY(i - j)]);
5335 #elif defined(BUF_TRACKING)
5336 db_printf("b_io_tracking: %s\n", bp->b_io_tracking);
5341 DB_SHOW_COMMAND(bufqueues, bufqueues)
5343 struct bufdomain *bd;
5348 db_printf("bqempty: %d\n", bqempty.bq_len);
5350 for (i = 0; i < buf_domains; i++) {
5352 db_printf("Buf domain %d\n", i);
5353 db_printf("\tfreebufs\t%d\n", bd->bd_freebuffers);
5354 db_printf("\tlofreebufs\t%d\n", bd->bd_lofreebuffers);
5355 db_printf("\thifreebufs\t%d\n", bd->bd_hifreebuffers);
5357 db_printf("\tbufspace\t%ld\n", bd->bd_bufspace);
5358 db_printf("\tmaxbufspace\t%ld\n", bd->bd_maxbufspace);
5359 db_printf("\thibufspace\t%ld\n", bd->bd_hibufspace);
5360 db_printf("\tlobufspace\t%ld\n", bd->bd_lobufspace);
5361 db_printf("\tbufspacethresh\t%ld\n", bd->bd_bufspacethresh);
5363 db_printf("\tnumdirtybuffers\t%d\n", bd->bd_numdirtybuffers);
5364 db_printf("\tlodirtybuffers\t%d\n", bd->bd_lodirtybuffers);
5365 db_printf("\thidirtybuffers\t%d\n", bd->bd_hidirtybuffers);
5366 db_printf("\tdirtybufthresh\t%d\n", bd->bd_dirtybufthresh);
5369 TAILQ_FOREACH(bp, &bd->bd_cleanq->bq_queue, b_freelist)
5370 total += bp->b_bufsize;
5371 db_printf("\tcleanq count\t%d (%ld)\n",
5372 bd->bd_cleanq->bq_len, total);
5374 TAILQ_FOREACH(bp, &bd->bd_dirtyq.bq_queue, b_freelist)
5375 total += bp->b_bufsize;
5376 db_printf("\tdirtyq count\t%d (%ld)\n",
5377 bd->bd_dirtyq.bq_len, total);
5378 db_printf("\twakeup\t\t%d\n", bd->bd_wanted);
5379 db_printf("\tlim\t\t%d\n", bd->bd_lim);
5380 db_printf("\tCPU ");
5381 for (j = 0; j <= mp_maxid; j++)
5382 db_printf("%d, ", bd->bd_subq[j].bq_len);
5386 for (j = 0; j < nbuf; j++)
5387 if (buf[j].b_domain == i && BUF_ISLOCKED(&buf[j])) {
5389 total += buf[j].b_bufsize;
5391 db_printf("\tLocked buffers: %d space %ld\n", cnt, total);
5394 for (j = 0; j < nbuf; j++)
5395 if (buf[j].b_domain == i) {
5397 total += buf[j].b_bufsize;
5399 db_printf("\tTotal buffers: %d space %ld\n", cnt, total);
5403 DB_SHOW_COMMAND(lockedbufs, lockedbufs)
5408 for (i = 0; i < nbuf; i++) {
5410 if (BUF_ISLOCKED(bp)) {
5411 db_show_buffer((uintptr_t)bp, 1, 0, NULL);
5419 DB_SHOW_COMMAND(vnodebufs, db_show_vnodebufs)
5425 db_printf("usage: show vnodebufs <addr>\n");
5428 vp = (struct vnode *)addr;
5429 db_printf("Clean buffers:\n");
5430 TAILQ_FOREACH(bp, &vp->v_bufobj.bo_clean.bv_hd, b_bobufs) {
5431 db_show_buffer((uintptr_t)bp, 1, 0, NULL);
5434 db_printf("Dirty buffers:\n");
5435 TAILQ_FOREACH(bp, &vp->v_bufobj.bo_dirty.bv_hd, b_bobufs) {
5436 db_show_buffer((uintptr_t)bp, 1, 0, NULL);
5441 DB_COMMAND(countfreebufs, db_coundfreebufs)
5444 int i, used = 0, nfree = 0;
5447 db_printf("usage: countfreebufs\n");
5451 for (i = 0; i < nbuf; i++) {
5453 if (bp->b_qindex == QUEUE_EMPTY)
5459 db_printf("Counted %d free, %d used (%d tot)\n", nfree, used,
5461 db_printf("numfreebuffers is %d\n", numfreebuffers);