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>
60 #include <sys/limits.h>
62 #include <sys/malloc.h>
63 #include <sys/mount.h>
64 #include <sys/mutex.h>
65 #include <sys/kernel.h>
66 #include <sys/kthread.h>
68 #include <sys/racct.h>
69 #include <sys/resourcevar.h>
70 #include <sys/rwlock.h>
72 #include <sys/sysctl.h>
73 #include <sys/sysproto.h>
75 #include <sys/vmmeter.h>
76 #include <sys/vnode.h>
77 #include <sys/watchdog.h>
78 #include <geom/geom.h>
80 #include <vm/vm_param.h>
81 #include <vm/vm_kern.h>
82 #include <vm/vm_object.h>
83 #include <vm/vm_page.h>
84 #include <vm/vm_pageout.h>
85 #include <vm/vm_pager.h>
86 #include <vm/vm_extern.h>
87 #include <vm/vm_map.h>
88 #include <vm/swap_pager.h>
89 #include "opt_compat.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 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_locked_object(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, &altbufferflushes,
254 0, "Number of fsync flushes to limit dirty buffers");
255 static int recursiveflushes;
256 SYSCTL_INT(_vfs, OID_AUTO, recursiveflushes, CTLFLAG_RW, &recursiveflushes,
257 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_LONG|CTLFLAG_MPSAFE|CTLFLAG_RW, &lodirtybuffers,
265 __offsetof(struct bufdomain, bd_lodirtybuffers), sysctl_bufdomain_int, "L",
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_LONG|CTLFLAG_MPSAFE|CTLFLAG_RW, &hidirtybuffers,
270 __offsetof(struct bufdomain, bd_hidirtybuffers), sysctl_bufdomain_int, "L",
271 "When the number of dirty buffers is considered severe");
273 SYSCTL_PROC(_vfs, OID_AUTO, dirtybufthresh,
274 CTLTYPE_LONG|CTLFLAG_MPSAFE|CTLFLAG_RW, &dirtybufthresh,
275 __offsetof(struct bufdomain, bd_dirtybufthresh), sysctl_bufdomain_int, "L",
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_LONG|CTLFLAG_MPSAFE|CTLFLAG_RW, &lofreebuffers,
283 __offsetof(struct bufdomain, bd_lofreebuffers), sysctl_bufdomain_int, "L",
284 "Target number of free buffers");
285 static int hifreebuffers;
286 SYSCTL_PROC(_vfs, OID_AUTO, hifreebuffers,
287 CTLTYPE_LONG|CTLFLAG_MPSAFE|CTLFLAG_RW, &hifreebuffers,
288 __offsetof(struct bufdomain, bd_hifreebuffers), sysctl_bufdomain_int, "L",
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, &barrierwrites, 0,
313 "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)&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)&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;
797 kproc_suspend_check(curproc);
800 * Free buffers from the clean queue until we meet our
803 * Theory of operation: The buffer cache is most efficient
804 * when some free buffer headers and space are always
805 * available to getnewbuf(). This daemon attempts to prevent
806 * the excessive blocking and synchronization associated
807 * with shortfall. It goes through three phases according
810 * 1) The daemon wakes up voluntarily once per-second
811 * during idle periods when the counters are below
812 * the wakeup thresholds (bufspacethresh, lofreebuffers).
814 * 2) The daemon wakes up as we cross the thresholds
815 * ahead of any potential blocking. This may bounce
816 * slightly according to the rate of consumption and
819 * 3) The daemon and consumers are starved for working
820 * clean buffers. This is the 'bufspace' sleep below
821 * which will inefficiently trade bufs with bqrelse
822 * until we return to condition 2.
825 if (buf_recycle(bd, false) != 0) {
829 * Speedup dirty if we've run out of clean
830 * buffers. This is possible in particular
831 * because softdep may held many bufs locked
832 * pending writes to other bufs which are
833 * marked for delayed write, exhausting
834 * clean space until they are written.
839 msleep(&bd->bd_wanted, BD_LOCKPTR(bd),
840 PRIBIO|PDROP, "bufspace", hz/10);
845 } while (bd->bd_bufspace > bd->bd_lobufspace ||
846 bd->bd_freebuffers < bd->bd_hifreebuffers);
848 bufspace_daemon_wait(bd);
855 * Adjust the reported bufspace for a malloc managed buffer, possibly
856 * waking any waiters.
859 bufmallocadjust(struct buf *bp, int bufsize)
863 KASSERT((bp->b_flags & B_MALLOC) != 0,
864 ("bufmallocadjust: non-malloc buf %p", bp));
865 diff = bufsize - bp->b_bufsize;
867 atomic_subtract_long(&bufmallocspace, -diff);
869 atomic_add_long(&bufmallocspace, diff);
870 bp->b_bufsize = bufsize;
876 * Wake up processes that are waiting on asynchronous writes to fall
877 * below lorunningspace.
883 mtx_lock(&rbreqlock);
886 wakeup(&runningbufreq);
888 mtx_unlock(&rbreqlock);
894 * Decrement the outstanding write count according.
897 runningbufwakeup(struct buf *bp)
901 bspace = bp->b_runningbufspace;
904 space = atomic_fetchadd_long(&runningbufspace, -bspace);
905 KASSERT(space >= bspace, ("runningbufspace underflow %ld %ld",
907 bp->b_runningbufspace = 0;
909 * Only acquire the lock and wakeup on the transition from exceeding
910 * the threshold to falling below it.
912 if (space < lorunningspace)
914 if (space - bspace > lorunningspace)
920 * waitrunningbufspace()
922 * runningbufspace is a measure of the amount of I/O currently
923 * running. This routine is used in async-write situations to
924 * prevent creating huge backups of pending writes to a device.
925 * Only asynchronous writes are governed by this function.
927 * This does NOT turn an async write into a sync write. It waits
928 * for earlier writes to complete and generally returns before the
929 * caller's write has reached the device.
932 waitrunningbufspace(void)
935 mtx_lock(&rbreqlock);
936 while (runningbufspace > hirunningspace) {
938 msleep(&runningbufreq, &rbreqlock, PVM, "wdrain", 0);
940 mtx_unlock(&rbreqlock);
945 * vfs_buf_test_cache:
947 * Called when a buffer is extended. This function clears the B_CACHE
948 * bit if the newly extended portion of the buffer does not contain
952 vfs_buf_test_cache(struct buf *bp, vm_ooffset_t foff, vm_offset_t off,
953 vm_offset_t size, vm_page_t m)
956 VM_OBJECT_ASSERT_LOCKED(m->object);
957 if (bp->b_flags & B_CACHE) {
958 int base = (foff + off) & PAGE_MASK;
959 if (vm_page_is_valid(m, base, size) == 0)
960 bp->b_flags &= ~B_CACHE;
964 /* Wake up the buffer daemon if necessary */
970 if (bd_request == 0) {
978 * Adjust the maxbcachbuf tunable.
981 maxbcachebuf_adjust(void)
986 * maxbcachebuf must be a power of 2 >= MAXBSIZE.
989 while (i * 2 <= maxbcachebuf)
992 if (maxbcachebuf < MAXBSIZE)
993 maxbcachebuf = MAXBSIZE;
994 if (maxbcachebuf > MAXPHYS)
995 maxbcachebuf = MAXPHYS;
996 if (bootverbose != 0 && maxbcachebuf != MAXBCACHEBUF)
997 printf("maxbcachebuf=%d\n", maxbcachebuf);
1001 * bd_speedup - speedup the buffer cache flushing code
1010 if (bd_speedupreq == 0 || bd_request == 0)
1015 wakeup(&bd_request);
1016 mtx_unlock(&bdlock);
1020 #define NSWBUF_MIN 16
1024 #define TRANSIENT_DENOM 5
1026 #define TRANSIENT_DENOM 10
1030 * Calculating buffer cache scaling values and reserve space for buffer
1031 * headers. This is called during low level kernel initialization and
1032 * may be called more then once. We CANNOT write to the memory area
1033 * being reserved at this time.
1036 kern_vfs_bio_buffer_alloc(caddr_t v, long physmem_est)
1039 long maxbuf, maxbuf_sz, buf_sz, biotmap_sz;
1042 * physmem_est is in pages. Convert it to kilobytes (assumes
1043 * PAGE_SIZE is >= 1K)
1045 physmem_est = physmem_est * (PAGE_SIZE / 1024);
1047 maxbcachebuf_adjust();
1049 * The nominal buffer size (and minimum KVA allocation) is BKVASIZE.
1050 * For the first 64MB of ram nominally allocate sufficient buffers to
1051 * cover 1/4 of our ram. Beyond the first 64MB allocate additional
1052 * buffers to cover 1/10 of our ram over 64MB. When auto-sizing
1053 * the buffer cache we limit the eventual kva reservation to
1056 * factor represents the 1/4 x ram conversion.
1059 int factor = 4 * BKVASIZE / 1024;
1062 if (physmem_est > 4096)
1063 nbuf += min((physmem_est - 4096) / factor,
1065 if (physmem_est > 65536)
1066 nbuf += min((physmem_est - 65536) * 2 / (factor * 5),
1067 32 * 1024 * 1024 / (factor * 5));
1069 if (maxbcache && nbuf > maxbcache / BKVASIZE)
1070 nbuf = maxbcache / BKVASIZE;
1075 /* XXX Avoid unsigned long overflows later on with maxbufspace. */
1076 maxbuf = (LONG_MAX / 3) / BKVASIZE;
1077 if (nbuf > maxbuf) {
1079 printf("Warning: nbufs lowered from %d to %ld\n", nbuf,
1085 * Ideal allocation size for the transient bio submap is 10%
1086 * of the maximal space buffer map. This roughly corresponds
1087 * to the amount of the buffer mapped for typical UFS load.
1089 * Clip the buffer map to reserve space for the transient
1090 * BIOs, if its extent is bigger than 90% (80% on i386) of the
1091 * maximum buffer map extent on the platform.
1093 * The fall-back to the maxbuf in case of maxbcache unset,
1094 * allows to not trim the buffer KVA for the architectures
1095 * with ample KVA space.
1097 if (bio_transient_maxcnt == 0 && unmapped_buf_allowed) {
1098 maxbuf_sz = maxbcache != 0 ? maxbcache : maxbuf * BKVASIZE;
1099 buf_sz = (long)nbuf * BKVASIZE;
1100 if (buf_sz < maxbuf_sz / TRANSIENT_DENOM *
1101 (TRANSIENT_DENOM - 1)) {
1103 * There is more KVA than memory. Do not
1104 * adjust buffer map size, and assign the rest
1105 * of maxbuf to transient map.
1107 biotmap_sz = maxbuf_sz - buf_sz;
1110 * Buffer map spans all KVA we could afford on
1111 * this platform. Give 10% (20% on i386) of
1112 * the buffer map to the transient bio map.
1114 biotmap_sz = buf_sz / TRANSIENT_DENOM;
1115 buf_sz -= biotmap_sz;
1117 if (biotmap_sz / INT_MAX > MAXPHYS)
1118 bio_transient_maxcnt = INT_MAX;
1120 bio_transient_maxcnt = biotmap_sz / MAXPHYS;
1122 * Artificially limit to 1024 simultaneous in-flight I/Os
1123 * using the transient mapping.
1125 if (bio_transient_maxcnt > 1024)
1126 bio_transient_maxcnt = 1024;
1128 nbuf = buf_sz / BKVASIZE;
1132 * swbufs are used as temporary holders for I/O, such as paging I/O.
1133 * We have no less then 16 and no more then 256.
1135 nswbuf = min(nbuf / 4, 256);
1136 TUNABLE_INT_FETCH("kern.nswbuf", &nswbuf);
1137 if (nswbuf < NSWBUF_MIN)
1138 nswbuf = NSWBUF_MIN;
1141 * Reserve space for the buffer cache buffers
1144 v = (caddr_t)(swbuf + nswbuf);
1146 v = (caddr_t)(buf + nbuf);
1151 /* Initialize the buffer subsystem. Called before use of any buffers. */
1158 KASSERT(maxbcachebuf >= MAXBSIZE,
1159 ("maxbcachebuf (%d) must be >= MAXBSIZE (%d)\n", maxbcachebuf,
1161 bq_init(&bqempty, QUEUE_EMPTY, -1, "bufq empty lock");
1162 mtx_init(&rbreqlock, "runningbufspace lock", NULL, MTX_DEF);
1163 mtx_init(&bdlock, "buffer daemon lock", NULL, MTX_DEF);
1164 mtx_init(&bdirtylock, "dirty buf lock", NULL, MTX_DEF);
1166 unmapped_buf = (caddr_t)kva_alloc(MAXPHYS);
1168 /* finally, initialize each buffer header and stick on empty q */
1169 for (i = 0; i < nbuf; i++) {
1171 bzero(bp, sizeof *bp);
1172 bp->b_flags = B_INVAL;
1173 bp->b_rcred = NOCRED;
1174 bp->b_wcred = NOCRED;
1175 bp->b_qindex = QUEUE_NONE;
1177 bp->b_subqueue = mp_maxid + 1;
1179 bp->b_data = bp->b_kvabase = unmapped_buf;
1180 LIST_INIT(&bp->b_dep);
1182 bq_insert(&bqempty, bp, false);
1186 * maxbufspace is the absolute maximum amount of buffer space we are
1187 * allowed to reserve in KVM and in real terms. The absolute maximum
1188 * is nominally used by metadata. hibufspace is the nominal maximum
1189 * used by most other requests. The differential is required to
1190 * ensure that metadata deadlocks don't occur.
1192 * maxbufspace is based on BKVASIZE. Allocating buffers larger then
1193 * this may result in KVM fragmentation which is not handled optimally
1194 * by the system. XXX This is less true with vmem. We could use
1197 maxbufspace = (long)nbuf * BKVASIZE;
1198 hibufspace = lmax(3 * maxbufspace / 4, maxbufspace - maxbcachebuf * 10);
1199 lobufspace = (hibufspace / 20) * 19; /* 95% */
1200 bufspacethresh = lobufspace + (hibufspace - lobufspace) / 2;
1203 * Note: The 16 MiB upper limit for hirunningspace was chosen
1204 * arbitrarily and may need further tuning. It corresponds to
1205 * 128 outstanding write IO requests (if IO size is 128 KiB),
1206 * which fits with many RAID controllers' tagged queuing limits.
1207 * The lower 1 MiB limit is the historical upper limit for
1210 hirunningspace = lmax(lmin(roundup(hibufspace / 64, maxbcachebuf),
1211 16 * 1024 * 1024), 1024 * 1024);
1212 lorunningspace = roundup((hirunningspace * 2) / 3, maxbcachebuf);
1215 * Limit the amount of malloc memory since it is wired permanently into
1216 * the kernel space. Even though this is accounted for in the buffer
1217 * allocation, we don't want the malloced region to grow uncontrolled.
1218 * The malloc scheme improves memory utilization significantly on
1219 * average (small) directories.
1221 maxbufmallocspace = hibufspace / 20;
1224 * Reduce the chance of a deadlock occurring by limiting the number
1225 * of delayed-write dirty buffers we allow to stack up.
1227 hidirtybuffers = nbuf / 4 + 20;
1228 dirtybufthresh = hidirtybuffers * 9 / 10;
1230 * To support extreme low-memory systems, make sure hidirtybuffers
1231 * cannot eat up all available buffer space. This occurs when our
1232 * minimum cannot be met. We try to size hidirtybuffers to 3/4 our
1233 * buffer space assuming BKVASIZE'd buffers.
1235 while ((long)hidirtybuffers * BKVASIZE > 3 * hibufspace / 4) {
1236 hidirtybuffers >>= 1;
1238 lodirtybuffers = hidirtybuffers / 2;
1241 * lofreebuffers should be sufficient to avoid stalling waiting on
1242 * buf headers under heavy utilization. The bufs in per-cpu caches
1243 * are counted as free but will be unavailable to threads executing
1246 * hifreebuffers is the free target for the bufspace daemon. This
1247 * should be set appropriately to limit work per-iteration.
1249 lofreebuffers = MIN((nbuf / 25) + (20 * mp_ncpus), 128 * mp_ncpus);
1250 hifreebuffers = (3 * lofreebuffers) / 2;
1251 numfreebuffers = nbuf;
1253 /* Setup the kva and free list allocators. */
1254 vmem_set_reclaim(buffer_arena, bufkva_reclaim);
1255 buf_zone = uma_zcache_create("buf free cache", sizeof(struct buf),
1256 NULL, NULL, NULL, NULL, buf_import, buf_release, NULL, 0);
1259 * Size the clean queue according to the amount of buffer space.
1260 * One queue per-256mb up to the max. More queues gives better
1261 * concurrency but less accurate LRU.
1263 buf_domains = MIN(howmany(maxbufspace, 256*1024*1024), BUF_DOMAINS);
1264 for (i = 0 ; i < buf_domains; i++) {
1265 struct bufdomain *bd;
1269 bd->bd_freebuffers = nbuf / buf_domains;
1270 bd->bd_hifreebuffers = hifreebuffers / buf_domains;
1271 bd->bd_lofreebuffers = lofreebuffers / buf_domains;
1272 bd->bd_bufspace = 0;
1273 bd->bd_maxbufspace = maxbufspace / buf_domains;
1274 bd->bd_hibufspace = hibufspace / buf_domains;
1275 bd->bd_lobufspace = lobufspace / buf_domains;
1276 bd->bd_bufspacethresh = bufspacethresh / buf_domains;
1277 bd->bd_numdirtybuffers = 0;
1278 bd->bd_hidirtybuffers = hidirtybuffers / buf_domains;
1279 bd->bd_lodirtybuffers = lodirtybuffers / buf_domains;
1280 bd->bd_dirtybufthresh = dirtybufthresh / buf_domains;
1281 /* Don't allow more than 2% of bufs in the per-cpu caches. */
1282 bd->bd_lim = nbuf / buf_domains / 50 / mp_ncpus;
1284 getnewbufcalls = counter_u64_alloc(M_WAITOK);
1285 getnewbufrestarts = counter_u64_alloc(M_WAITOK);
1286 mappingrestarts = counter_u64_alloc(M_WAITOK);
1287 numbufallocfails = counter_u64_alloc(M_WAITOK);
1288 notbufdflushes = counter_u64_alloc(M_WAITOK);
1289 buffreekvacnt = counter_u64_alloc(M_WAITOK);
1290 bufdefragcnt = counter_u64_alloc(M_WAITOK);
1291 bufkvaspace = counter_u64_alloc(M_WAITOK);
1296 vfs_buf_check_mapped(struct buf *bp)
1299 KASSERT(bp->b_kvabase != unmapped_buf,
1300 ("mapped buf: b_kvabase was not updated %p", bp));
1301 KASSERT(bp->b_data != unmapped_buf,
1302 ("mapped buf: b_data was not updated %p", bp));
1303 KASSERT(bp->b_data < unmapped_buf || bp->b_data >= unmapped_buf +
1304 MAXPHYS, ("b_data + b_offset unmapped %p", bp));
1308 vfs_buf_check_unmapped(struct buf *bp)
1311 KASSERT(bp->b_data == unmapped_buf,
1312 ("unmapped buf: corrupted b_data %p", bp));
1315 #define BUF_CHECK_MAPPED(bp) vfs_buf_check_mapped(bp)
1316 #define BUF_CHECK_UNMAPPED(bp) vfs_buf_check_unmapped(bp)
1318 #define BUF_CHECK_MAPPED(bp) do {} while (0)
1319 #define BUF_CHECK_UNMAPPED(bp) do {} while (0)
1323 isbufbusy(struct buf *bp)
1325 if (((bp->b_flags & B_INVAL) == 0 && BUF_ISLOCKED(bp)) ||
1326 ((bp->b_flags & (B_DELWRI | B_INVAL)) == B_DELWRI))
1332 * Shutdown the system cleanly to prepare for reboot, halt, or power off.
1335 bufshutdown(int show_busybufs)
1337 static int first_buf_printf = 1;
1339 int iter, nbusy, pbusy;
1345 * Sync filesystems for shutdown
1347 wdog_kern_pat(WD_LASTVAL);
1348 sys_sync(curthread, NULL);
1351 * With soft updates, some buffers that are
1352 * written will be remarked as dirty until other
1353 * buffers are written.
1355 for (iter = pbusy = 0; iter < 20; iter++) {
1357 for (bp = &buf[nbuf]; --bp >= buf; )
1361 if (first_buf_printf)
1362 printf("All buffers synced.");
1365 if (first_buf_printf) {
1366 printf("Syncing disks, buffers remaining... ");
1367 first_buf_printf = 0;
1369 printf("%d ", nbusy);
1374 wdog_kern_pat(WD_LASTVAL);
1375 sys_sync(curthread, NULL);
1379 * Drop Giant and spin for a while to allow
1380 * interrupt threads to run.
1383 DELAY(50000 * iter);
1387 * Drop Giant and context switch several times to
1388 * allow interrupt threads to run.
1391 for (subiter = 0; subiter < 50 * iter; subiter++) {
1392 thread_lock(curthread);
1393 mi_switch(SW_VOL, NULL);
1394 thread_unlock(curthread);
1402 * Count only busy local buffers to prevent forcing
1403 * a fsck if we're just a client of a wedged NFS server
1406 for (bp = &buf[nbuf]; --bp >= buf; ) {
1407 if (isbufbusy(bp)) {
1409 /* XXX: This is bogus. We should probably have a BO_REMOTE flag instead */
1410 if (bp->b_dev == NULL) {
1411 TAILQ_REMOVE(&mountlist,
1412 bp->b_vp->v_mount, mnt_list);
1417 if (show_busybufs > 0) {
1419 "%d: buf:%p, vnode:%p, flags:%0x, blkno:%jd, lblkno:%jd, buflock:",
1420 nbusy, bp, bp->b_vp, bp->b_flags,
1421 (intmax_t)bp->b_blkno,
1422 (intmax_t)bp->b_lblkno);
1423 BUF_LOCKPRINTINFO(bp);
1424 if (show_busybufs > 1)
1432 * Failed to sync all blocks. Indicate this and don't
1433 * unmount filesystems (thus forcing an fsck on reboot).
1435 printf("Giving up on %d buffers\n", nbusy);
1436 DELAY(5000000); /* 5 seconds */
1438 if (!first_buf_printf)
1439 printf("Final sync complete\n");
1441 * Unmount filesystems
1443 if (panicstr == NULL)
1447 DELAY(100000); /* wait for console output to finish */
1451 bpmap_qenter(struct buf *bp)
1454 BUF_CHECK_MAPPED(bp);
1457 * bp->b_data is relative to bp->b_offset, but
1458 * bp->b_offset may be offset into the first page.
1460 bp->b_data = (caddr_t)trunc_page((vm_offset_t)bp->b_data);
1461 pmap_qenter((vm_offset_t)bp->b_data, bp->b_pages, bp->b_npages);
1462 bp->b_data = (caddr_t)((vm_offset_t)bp->b_data |
1463 (vm_offset_t)(bp->b_offset & PAGE_MASK));
1466 static inline struct bufdomain *
1467 bufdomain(struct buf *bp)
1470 return (&bdomain[bp->b_domain]);
1473 static struct bufqueue *
1474 bufqueue(struct buf *bp)
1477 switch (bp->b_qindex) {
1480 case QUEUE_SENTINEL:
1485 return (&bufdomain(bp)->bd_dirtyq);
1487 return (&bufdomain(bp)->bd_subq[bp->b_subqueue]);
1491 panic("bufqueue(%p): Unhandled type %d\n", bp, bp->b_qindex);
1495 * Return the locked bufqueue that bp is a member of.
1497 static struct bufqueue *
1498 bufqueue_acquire(struct buf *bp)
1500 struct bufqueue *bq, *nbq;
1503 * bp can be pushed from a per-cpu queue to the
1504 * cleanq while we're waiting on the lock. Retry
1505 * if the queues don't match.
1523 * Insert the buffer into the appropriate free list. Requires a
1524 * locked buffer on entry and buffer is unlocked before return.
1527 binsfree(struct buf *bp, int qindex)
1529 struct bufdomain *bd;
1530 struct bufqueue *bq;
1532 KASSERT(qindex == QUEUE_CLEAN || qindex == QUEUE_DIRTY,
1533 ("binsfree: Invalid qindex %d", qindex));
1534 BUF_ASSERT_XLOCKED(bp);
1537 * Handle delayed bremfree() processing.
1539 if (bp->b_flags & B_REMFREE) {
1540 if (bp->b_qindex == qindex) {
1541 bp->b_flags |= B_REUSE;
1542 bp->b_flags &= ~B_REMFREE;
1546 bq = bufqueue_acquire(bp);
1551 if (qindex == QUEUE_CLEAN) {
1552 if (bd->bd_lim != 0)
1553 bq = &bd->bd_subq[PCPU_GET(cpuid)];
1557 bq = &bd->bd_dirtyq;
1558 bq_insert(bq, bp, true);
1564 * Free a buffer to the buf zone once it no longer has valid contents.
1567 buf_free(struct buf *bp)
1570 if (bp->b_flags & B_REMFREE)
1572 if (bp->b_vflags & BV_BKGRDINPROG)
1573 panic("losing buffer 1");
1574 if (bp->b_rcred != NOCRED) {
1575 crfree(bp->b_rcred);
1576 bp->b_rcred = NOCRED;
1578 if (bp->b_wcred != NOCRED) {
1579 crfree(bp->b_wcred);
1580 bp->b_wcred = NOCRED;
1582 if (!LIST_EMPTY(&bp->b_dep))
1585 atomic_add_int(&bufdomain(bp)->bd_freebuffers, 1);
1587 uma_zfree(buf_zone, bp);
1593 * Import bufs into the uma cache from the buf list. The system still
1594 * expects a static array of bufs and much of the synchronization
1595 * around bufs assumes type stable storage. As a result, UMA is used
1596 * only as a per-cpu cache of bufs still maintained on a global list.
1599 buf_import(void *arg, void **store, int cnt, int domain, int flags)
1605 for (i = 0; i < cnt; i++) {
1606 bp = TAILQ_FIRST(&bqempty.bq_queue);
1609 bq_remove(&bqempty, bp);
1612 BQ_UNLOCK(&bqempty);
1620 * Release bufs from the uma cache back to the buffer queues.
1623 buf_release(void *arg, void **store, int cnt)
1625 struct bufqueue *bq;
1631 for (i = 0; i < cnt; i++) {
1633 /* Inline bq_insert() to batch locking. */
1634 TAILQ_INSERT_TAIL(&bq->bq_queue, bp, b_freelist);
1635 bp->b_flags &= ~(B_AGE | B_REUSE);
1637 bp->b_qindex = bq->bq_index;
1645 * Allocate an empty buffer header.
1648 buf_alloc(struct bufdomain *bd)
1654 * We can only run out of bufs in the buf zone if the average buf
1655 * is less than BKVASIZE. In this case the actual wait/block will
1656 * come from buf_reycle() failing to flush one of these small bufs.
1659 freebufs = atomic_fetchadd_int(&bd->bd_freebuffers, -1);
1661 bp = uma_zalloc(buf_zone, M_NOWAIT);
1663 atomic_fetchadd_int(&bd->bd_freebuffers, 1);
1664 bufspace_daemon_wakeup(bd);
1665 counter_u64_add(numbufallocfails, 1);
1669 * Wake-up the bufspace daemon on transition below threshold.
1671 if (freebufs == bd->bd_lofreebuffers)
1672 bufspace_daemon_wakeup(bd);
1674 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0)
1675 panic("getnewbuf_empty: Locked buf %p on free queue.", bp);
1677 KASSERT(bp->b_vp == NULL,
1678 ("bp: %p still has vnode %p.", bp, bp->b_vp));
1679 KASSERT((bp->b_flags & (B_DELWRI | B_NOREUSE)) == 0,
1680 ("invalid buffer %p flags %#x", bp, bp->b_flags));
1681 KASSERT((bp->b_xflags & (BX_VNCLEAN|BX_VNDIRTY)) == 0,
1682 ("bp: %p still on a buffer list. xflags %X", bp, bp->b_xflags));
1683 KASSERT(bp->b_npages == 0,
1684 ("bp: %p still has %d vm pages\n", bp, bp->b_npages));
1685 KASSERT(bp->b_kvasize == 0, ("bp: %p still has kva\n", bp));
1686 KASSERT(bp->b_bufsize == 0, ("bp: %p still has bufspace\n", bp));
1688 bp->b_domain = BD_DOMAIN(bd);
1694 bp->b_blkno = bp->b_lblkno = 0;
1695 bp->b_offset = NOOFFSET;
1701 bp->b_dirtyoff = bp->b_dirtyend = 0;
1702 bp->b_bufobj = NULL;
1703 bp->b_data = bp->b_kvabase = unmapped_buf;
1704 bp->b_fsprivate1 = NULL;
1705 bp->b_fsprivate2 = NULL;
1706 bp->b_fsprivate3 = NULL;
1707 LIST_INIT(&bp->b_dep);
1715 * Free a buffer from the given bufqueue. kva controls whether the
1716 * freed buf must own some kva resources. This is used for
1720 buf_recycle(struct bufdomain *bd, bool kva)
1722 struct bufqueue *bq;
1723 struct buf *bp, *nbp;
1726 counter_u64_add(bufdefragcnt, 1);
1730 KASSERT(BQ_LOCKPTR(bq) == BD_LOCKPTR(bd),
1731 ("buf_recycle: Locks don't match"));
1732 nbp = TAILQ_FIRST(&bq->bq_queue);
1735 * Run scan, possibly freeing data and/or kva mappings on the fly
1738 while ((bp = nbp) != NULL) {
1740 * Calculate next bp (we can only use it if we do not
1741 * release the bqlock).
1743 nbp = TAILQ_NEXT(bp, b_freelist);
1746 * If we are defragging then we need a buffer with
1747 * some kva to reclaim.
1749 if (kva && bp->b_kvasize == 0)
1752 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0)
1756 * Implement a second chance algorithm for frequently
1759 if ((bp->b_flags & B_REUSE) != 0) {
1760 TAILQ_REMOVE(&bq->bq_queue, bp, b_freelist);
1761 TAILQ_INSERT_TAIL(&bq->bq_queue, bp, b_freelist);
1762 bp->b_flags &= ~B_REUSE;
1768 * Skip buffers with background writes in progress.
1770 if ((bp->b_vflags & BV_BKGRDINPROG) != 0) {
1775 KASSERT(bp->b_qindex == QUEUE_CLEAN,
1776 ("buf_recycle: inconsistent queue %d bp %p",
1778 KASSERT(bp->b_domain == BD_DOMAIN(bd),
1779 ("getnewbuf: queue domain %d doesn't match request %d",
1780 bp->b_domain, (int)BD_DOMAIN(bd)));
1782 * NOTE: nbp is now entirely invalid. We can only restart
1783 * the scan from this point on.
1789 * Requeue the background write buffer with error and
1792 if ((bp->b_vflags & BV_BKGRDERR) != 0) {
1795 nbp = TAILQ_FIRST(&bq->bq_queue);
1798 bp->b_flags |= B_INVAL;
1811 * Mark the buffer for removal from the appropriate free list.
1815 bremfree(struct buf *bp)
1818 CTR3(KTR_BUF, "bremfree(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
1819 KASSERT((bp->b_flags & B_REMFREE) == 0,
1820 ("bremfree: buffer %p already marked for delayed removal.", bp));
1821 KASSERT(bp->b_qindex != QUEUE_NONE,
1822 ("bremfree: buffer %p not on a queue.", bp));
1823 BUF_ASSERT_XLOCKED(bp);
1825 bp->b_flags |= B_REMFREE;
1831 * Force an immediate removal from a free list. Used only in nfs when
1832 * it abuses the b_freelist pointer.
1835 bremfreef(struct buf *bp)
1837 struct bufqueue *bq;
1839 bq = bufqueue_acquire(bp);
1845 bq_init(struct bufqueue *bq, int qindex, int subqueue, const char *lockname)
1848 mtx_init(&bq->bq_lock, lockname, NULL, MTX_DEF);
1849 TAILQ_INIT(&bq->bq_queue);
1851 bq->bq_index = qindex;
1852 bq->bq_subqueue = subqueue;
1856 bd_init(struct bufdomain *bd)
1861 domain = bd - bdomain;
1862 bd->bd_cleanq = &bd->bd_subq[mp_maxid + 1];
1863 bq_init(bd->bd_cleanq, QUEUE_CLEAN, mp_maxid + 1, "bufq clean lock");
1864 bq_init(&bd->bd_dirtyq, QUEUE_DIRTY, -1, "bufq dirty lock");
1865 for (i = 0; i <= mp_maxid; i++)
1866 bq_init(&bd->bd_subq[i], QUEUE_CLEAN, i,
1867 "bufq clean subqueue lock");
1868 mtx_init(&bd->bd_run_lock, "bufspace daemon run lock", NULL, MTX_DEF);
1874 * Removes a buffer from the free list, must be called with the
1875 * correct qlock held.
1878 bq_remove(struct bufqueue *bq, struct buf *bp)
1881 CTR3(KTR_BUF, "bq_remove(%p) vp %p flags %X",
1882 bp, bp->b_vp, bp->b_flags);
1883 KASSERT(bp->b_qindex != QUEUE_NONE,
1884 ("bq_remove: buffer %p not on a queue.", bp));
1885 KASSERT(bufqueue(bp) == bq,
1886 ("bq_remove: Remove buffer %p from wrong queue.", bp));
1888 BQ_ASSERT_LOCKED(bq);
1889 if (bp->b_qindex != QUEUE_EMPTY) {
1890 BUF_ASSERT_XLOCKED(bp);
1892 KASSERT(bq->bq_len >= 1,
1893 ("queue %d underflow", bp->b_qindex));
1894 TAILQ_REMOVE(&bq->bq_queue, bp, b_freelist);
1896 bp->b_qindex = QUEUE_NONE;
1897 bp->b_flags &= ~(B_REMFREE | B_REUSE);
1901 bd_flush(struct bufdomain *bd, struct bufqueue *bq)
1905 BQ_ASSERT_LOCKED(bq);
1906 if (bq != bd->bd_cleanq) {
1908 while ((bp = TAILQ_FIRST(&bq->bq_queue)) != NULL) {
1909 TAILQ_REMOVE(&bq->bq_queue, bp, b_freelist);
1910 TAILQ_INSERT_TAIL(&bd->bd_cleanq->bq_queue, bp,
1912 bp->b_subqueue = bd->bd_cleanq->bq_subqueue;
1914 bd->bd_cleanq->bq_len += bq->bq_len;
1917 if (bd->bd_wanted) {
1919 wakeup(&bd->bd_wanted);
1921 if (bq != bd->bd_cleanq)
1926 bd_flushall(struct bufdomain *bd)
1928 struct bufqueue *bq;
1932 if (bd->bd_lim == 0)
1935 for (i = 0; i <= mp_maxid; i++) {
1936 bq = &bd->bd_subq[i];
1937 if (bq->bq_len == 0)
1949 bq_insert(struct bufqueue *bq, struct buf *bp, bool unlock)
1951 struct bufdomain *bd;
1953 if (bp->b_qindex != QUEUE_NONE)
1954 panic("bq_insert: free buffer %p onto another queue?", bp);
1957 if (bp->b_flags & B_AGE) {
1958 /* Place this buf directly on the real queue. */
1959 if (bq->bq_index == QUEUE_CLEAN)
1962 TAILQ_INSERT_HEAD(&bq->bq_queue, bp, b_freelist);
1965 TAILQ_INSERT_TAIL(&bq->bq_queue, bp, b_freelist);
1967 bp->b_flags &= ~(B_AGE | B_REUSE);
1969 bp->b_qindex = bq->bq_index;
1970 bp->b_subqueue = bq->bq_subqueue;
1973 * Unlock before we notify so that we don't wakeup a waiter that
1974 * fails a trylock on the buf and sleeps again.
1979 if (bp->b_qindex == QUEUE_CLEAN) {
1981 * Flush the per-cpu queue and notify any waiters.
1983 if (bd->bd_wanted || (bq != bd->bd_cleanq &&
1984 bq->bq_len >= bd->bd_lim))
1993 * Free the kva allocation for a buffer.
1997 bufkva_free(struct buf *bp)
2001 if (bp->b_kvasize == 0) {
2002 KASSERT(bp->b_kvabase == unmapped_buf &&
2003 bp->b_data == unmapped_buf,
2004 ("Leaked KVA space on %p", bp));
2005 } else if (buf_mapped(bp))
2006 BUF_CHECK_MAPPED(bp);
2008 BUF_CHECK_UNMAPPED(bp);
2010 if (bp->b_kvasize == 0)
2013 vmem_free(buffer_arena, (vm_offset_t)bp->b_kvabase, bp->b_kvasize);
2014 counter_u64_add(bufkvaspace, -bp->b_kvasize);
2015 counter_u64_add(buffreekvacnt, 1);
2016 bp->b_data = bp->b_kvabase = unmapped_buf;
2023 * Allocate the buffer KVA and set b_kvasize and b_kvabase.
2026 bufkva_alloc(struct buf *bp, int maxsize, int gbflags)
2031 KASSERT((gbflags & GB_UNMAPPED) == 0 || (gbflags & GB_KVAALLOC) != 0,
2032 ("Invalid gbflags 0x%x in %s", gbflags, __func__));
2037 error = vmem_alloc(buffer_arena, maxsize, M_BESTFIT | M_NOWAIT, &addr);
2040 * Buffer map is too fragmented. Request the caller
2041 * to defragment the map.
2045 bp->b_kvabase = (caddr_t)addr;
2046 bp->b_kvasize = maxsize;
2047 counter_u64_add(bufkvaspace, bp->b_kvasize);
2048 if ((gbflags & GB_UNMAPPED) != 0) {
2049 bp->b_data = unmapped_buf;
2050 BUF_CHECK_UNMAPPED(bp);
2052 bp->b_data = bp->b_kvabase;
2053 BUF_CHECK_MAPPED(bp);
2061 * Reclaim buffer kva by freeing buffers holding kva. This is a vmem
2062 * callback that fires to avoid returning failure.
2065 bufkva_reclaim(vmem_t *vmem, int flags)
2072 for (i = 0; i < 5; i++) {
2073 for (q = 0; q < buf_domains; q++)
2074 if (buf_recycle(&bdomain[q], true) != 0)
2083 * Attempt to initiate asynchronous I/O on read-ahead blocks. We must
2084 * clear BIO_ERROR and B_INVAL prior to initiating I/O . If B_CACHE is set,
2085 * the buffer is valid and we do not have to do anything.
2088 breada(struct vnode * vp, daddr_t * rablkno, int * rabsize, int cnt,
2089 struct ucred * cred, int flags, void (*ckhashfunc)(struct buf *))
2094 for (i = 0; i < cnt; i++, rablkno++, rabsize++) {
2095 if (inmem(vp, *rablkno))
2097 rabp = getblk(vp, *rablkno, *rabsize, 0, 0, 0);
2098 if ((rabp->b_flags & B_CACHE) != 0) {
2102 if (!TD_IS_IDLETHREAD(curthread)) {
2106 racct_add_buf(curproc, rabp, 0);
2107 PROC_UNLOCK(curproc);
2110 curthread->td_ru.ru_inblock++;
2112 rabp->b_flags |= B_ASYNC;
2113 rabp->b_flags &= ~B_INVAL;
2114 if ((flags & GB_CKHASH) != 0) {
2115 rabp->b_flags |= B_CKHASH;
2116 rabp->b_ckhashcalc = ckhashfunc;
2118 rabp->b_ioflags &= ~BIO_ERROR;
2119 rabp->b_iocmd = BIO_READ;
2120 if (rabp->b_rcred == NOCRED && cred != NOCRED)
2121 rabp->b_rcred = crhold(cred);
2122 vfs_busy_pages(rabp, 0);
2124 rabp->b_iooffset = dbtob(rabp->b_blkno);
2130 * Entry point for bread() and breadn() via #defines in sys/buf.h.
2132 * Get a buffer with the specified data. Look in the cache first. We
2133 * must clear BIO_ERROR and B_INVAL prior to initiating I/O. If B_CACHE
2134 * is set, the buffer is valid and we do not have to do anything, see
2135 * getblk(). Also starts asynchronous I/O on read-ahead blocks.
2137 * Always return a NULL buffer pointer (in bpp) when returning an error.
2140 breadn_flags(struct vnode *vp, daddr_t blkno, int size, daddr_t *rablkno,
2141 int *rabsize, int cnt, struct ucred *cred, int flags,
2142 void (*ckhashfunc)(struct buf *), struct buf **bpp)
2147 CTR3(KTR_BUF, "breadn(%p, %jd, %d)", vp, blkno, size);
2149 * Can only return NULL if GB_LOCK_NOWAIT flag is specified.
2151 *bpp = bp = getblk(vp, blkno, size, 0, 0, flags);
2156 * If not found in cache, do some I/O
2159 if ((bp->b_flags & B_CACHE) == 0) {
2160 if (!TD_IS_IDLETHREAD(curthread)) {
2164 racct_add_buf(curproc, bp, 0);
2165 PROC_UNLOCK(curproc);
2168 curthread->td_ru.ru_inblock++;
2170 bp->b_iocmd = BIO_READ;
2171 bp->b_flags &= ~B_INVAL;
2172 if ((flags & GB_CKHASH) != 0) {
2173 bp->b_flags |= B_CKHASH;
2174 bp->b_ckhashcalc = ckhashfunc;
2176 bp->b_ioflags &= ~BIO_ERROR;
2177 if (bp->b_rcred == NOCRED && cred != NOCRED)
2178 bp->b_rcred = crhold(cred);
2179 vfs_busy_pages(bp, 0);
2180 bp->b_iooffset = dbtob(bp->b_blkno);
2186 * Attempt to initiate asynchronous I/O on read-ahead blocks.
2188 breada(vp, rablkno, rabsize, cnt, cred, flags, ckhashfunc);
2202 * Write, release buffer on completion. (Done by iodone
2203 * if async). Do not bother writing anything if the buffer
2206 * Note that we set B_CACHE here, indicating that buffer is
2207 * fully valid and thus cacheable. This is true even of NFS
2208 * now so we set it generally. This could be set either here
2209 * or in biodone() since the I/O is synchronous. We put it
2213 bufwrite(struct buf *bp)
2220 CTR3(KTR_BUF, "bufwrite(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
2221 if ((bp->b_bufobj->bo_flag & BO_DEAD) != 0) {
2222 bp->b_flags |= B_INVAL | B_RELBUF;
2223 bp->b_flags &= ~B_CACHE;
2227 if (bp->b_flags & B_INVAL) {
2232 if (bp->b_flags & B_BARRIER)
2235 oldflags = bp->b_flags;
2237 BUF_ASSERT_HELD(bp);
2239 KASSERT(!(bp->b_vflags & BV_BKGRDINPROG),
2240 ("FFS background buffer should not get here %p", bp));
2244 vp_md = vp->v_vflag & VV_MD;
2249 * Mark the buffer clean. Increment the bufobj write count
2250 * before bundirty() call, to prevent other thread from seeing
2251 * empty dirty list and zero counter for writes in progress,
2252 * falsely indicating that the bufobj is clean.
2254 bufobj_wref(bp->b_bufobj);
2257 bp->b_flags &= ~B_DONE;
2258 bp->b_ioflags &= ~BIO_ERROR;
2259 bp->b_flags |= B_CACHE;
2260 bp->b_iocmd = BIO_WRITE;
2262 vfs_busy_pages(bp, 1);
2265 * Normal bwrites pipeline writes
2267 bp->b_runningbufspace = bp->b_bufsize;
2268 space = atomic_fetchadd_long(&runningbufspace, bp->b_runningbufspace);
2270 if (!TD_IS_IDLETHREAD(curthread)) {
2274 racct_add_buf(curproc, bp, 1);
2275 PROC_UNLOCK(curproc);
2278 curthread->td_ru.ru_oublock++;
2280 if (oldflags & B_ASYNC)
2282 bp->b_iooffset = dbtob(bp->b_blkno);
2283 buf_track(bp, __func__);
2286 if ((oldflags & B_ASYNC) == 0) {
2287 int rtval = bufwait(bp);
2290 } else if (space > hirunningspace) {
2292 * don't allow the async write to saturate the I/O
2293 * system. We will not deadlock here because
2294 * we are blocking waiting for I/O that is already in-progress
2295 * to complete. We do not block here if it is the update
2296 * or syncer daemon trying to clean up as that can lead
2299 if ((curthread->td_pflags & TDP_NORUNNINGBUF) == 0 && !vp_md)
2300 waitrunningbufspace();
2307 bufbdflush(struct bufobj *bo, struct buf *bp)
2311 if (bo->bo_dirty.bv_cnt > dirtybufthresh + 10) {
2312 (void) VOP_FSYNC(bp->b_vp, MNT_NOWAIT, curthread);
2314 } else if (bo->bo_dirty.bv_cnt > dirtybufthresh) {
2317 * Try to find a buffer to flush.
2319 TAILQ_FOREACH(nbp, &bo->bo_dirty.bv_hd, b_bobufs) {
2320 if ((nbp->b_vflags & BV_BKGRDINPROG) ||
2322 LK_EXCLUSIVE | LK_NOWAIT, NULL))
2325 panic("bdwrite: found ourselves");
2327 /* Don't countdeps with the bo lock held. */
2328 if (buf_countdeps(nbp, 0)) {
2333 if (nbp->b_flags & B_CLUSTEROK) {
2334 vfs_bio_awrite(nbp);
2339 dirtybufferflushes++;
2348 * Delayed write. (Buffer is marked dirty). Do not bother writing
2349 * anything if the buffer is marked invalid.
2351 * Note that since the buffer must be completely valid, we can safely
2352 * set B_CACHE. In fact, we have to set B_CACHE here rather then in
2353 * biodone() in order to prevent getblk from writing the buffer
2354 * out synchronously.
2357 bdwrite(struct buf *bp)
2359 struct thread *td = curthread;
2363 CTR3(KTR_BUF, "bdwrite(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
2364 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp));
2365 KASSERT((bp->b_flags & B_BARRIER) == 0,
2366 ("Barrier request in delayed write %p", bp));
2367 BUF_ASSERT_HELD(bp);
2369 if (bp->b_flags & B_INVAL) {
2375 * If we have too many dirty buffers, don't create any more.
2376 * If we are wildly over our limit, then force a complete
2377 * cleanup. Otherwise, just keep the situation from getting
2378 * out of control. Note that we have to avoid a recursive
2379 * disaster and not try to clean up after our own cleanup!
2383 if ((td->td_pflags & (TDP_COWINPROGRESS|TDP_INBDFLUSH)) == 0) {
2384 td->td_pflags |= TDP_INBDFLUSH;
2386 td->td_pflags &= ~TDP_INBDFLUSH;
2392 * Set B_CACHE, indicating that the buffer is fully valid. This is
2393 * true even of NFS now.
2395 bp->b_flags |= B_CACHE;
2398 * This bmap keeps the system from needing to do the bmap later,
2399 * perhaps when the system is attempting to do a sync. Since it
2400 * is likely that the indirect block -- or whatever other datastructure
2401 * that the filesystem needs is still in memory now, it is a good
2402 * thing to do this. Note also, that if the pageout daemon is
2403 * requesting a sync -- there might not be enough memory to do
2404 * the bmap then... So, this is important to do.
2406 if (vp->v_type != VCHR && bp->b_lblkno == bp->b_blkno) {
2407 VOP_BMAP(vp, bp->b_lblkno, NULL, &bp->b_blkno, NULL, NULL);
2410 buf_track(bp, __func__);
2413 * Set the *dirty* buffer range based upon the VM system dirty
2416 * Mark the buffer pages as clean. We need to do this here to
2417 * satisfy the vnode_pager and the pageout daemon, so that it
2418 * thinks that the pages have been "cleaned". Note that since
2419 * the pages are in a delayed write buffer -- the VFS layer
2420 * "will" see that the pages get written out on the next sync,
2421 * or perhaps the cluster will be completed.
2423 vfs_clean_pages_dirty_buf(bp);
2427 * note: we cannot initiate I/O from a bdwrite even if we wanted to,
2428 * due to the softdep code.
2435 * Turn buffer into delayed write request. We must clear BIO_READ and
2436 * B_RELBUF, and we must set B_DELWRI. We reassign the buffer to
2437 * itself to properly update it in the dirty/clean lists. We mark it
2438 * B_DONE to ensure that any asynchronization of the buffer properly
2439 * clears B_DONE ( else a panic will occur later ).
2441 * bdirty() is kinda like bdwrite() - we have to clear B_INVAL which
2442 * might have been set pre-getblk(). Unlike bwrite/bdwrite, bdirty()
2443 * should only be called if the buffer is known-good.
2445 * Since the buffer is not on a queue, we do not update the numfreebuffers
2448 * The buffer must be on QUEUE_NONE.
2451 bdirty(struct buf *bp)
2454 CTR3(KTR_BUF, "bdirty(%p) vp %p flags %X",
2455 bp, bp->b_vp, bp->b_flags);
2456 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp));
2457 KASSERT(bp->b_flags & B_REMFREE || bp->b_qindex == QUEUE_NONE,
2458 ("bdirty: buffer %p still on queue %d", bp, bp->b_qindex));
2459 BUF_ASSERT_HELD(bp);
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));
2489 BUF_ASSERT_HELD(bp);
2491 if (bp->b_flags & B_DELWRI) {
2492 bp->b_flags &= ~B_DELWRI;
2497 * Since it is now being written, we can clear its deferred write flag.
2499 bp->b_flags &= ~B_DEFERRED;
2505 * Asynchronous write. Start output on a buffer, but do not wait for
2506 * it to complete. The buffer is released when the output completes.
2508 * bwrite() ( or the VOP routine anyway ) is responsible for handling
2509 * B_INVAL buffers. Not us.
2512 bawrite(struct buf *bp)
2515 bp->b_flags |= B_ASYNC;
2522 * Asynchronous barrier write. Start output on a buffer, but do not
2523 * wait for it to complete. Place a write barrier after this write so
2524 * that this buffer and all buffers written before it are committed to
2525 * the disk before any buffers written after this write are committed
2526 * to the disk. The buffer is released when the output completes.
2529 babarrierwrite(struct buf *bp)
2532 bp->b_flags |= B_ASYNC | B_BARRIER;
2539 * Synchronous barrier write. Start output on a buffer and wait for
2540 * it to complete. Place a write barrier after this write so that
2541 * this buffer and all buffers written before it are committed to
2542 * the disk before any buffers written after this write are committed
2543 * to the disk. The buffer is released when the output completes.
2546 bbarrierwrite(struct buf *bp)
2549 bp->b_flags |= B_BARRIER;
2550 return (bwrite(bp));
2556 * Called prior to the locking of any vnodes when we are expecting to
2557 * write. We do not want to starve the buffer cache with too many
2558 * dirty buffers so we block here. By blocking prior to the locking
2559 * of any vnodes we attempt to avoid the situation where a locked vnode
2560 * prevents the various system daemons from flushing related buffers.
2566 if (buf_dirty_count_severe()) {
2567 mtx_lock(&bdirtylock);
2568 while (buf_dirty_count_severe()) {
2570 msleep(&bdirtywait, &bdirtylock, (PRIBIO + 4),
2573 mtx_unlock(&bdirtylock);
2578 * Return true if we have too many dirty buffers.
2581 buf_dirty_count_severe(void)
2584 return (!BIT_EMPTY(BUF_DOMAINS, &bdhidirty));
2590 * Release a busy buffer and, if requested, free its resources. The
2591 * buffer will be stashed in the appropriate bufqueue[] allowing it
2592 * to be accessed later as a cache entity or reused for other purposes.
2595 brelse(struct buf *bp)
2597 struct mount *v_mnt;
2601 * Many functions erroneously call brelse with a NULL bp under rare
2602 * error conditions. Simply return when called with a NULL bp.
2606 CTR3(KTR_BUF, "brelse(%p) vp %p flags %X",
2607 bp, bp->b_vp, bp->b_flags);
2608 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)),
2609 ("brelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp));
2610 KASSERT((bp->b_flags & B_VMIO) != 0 || (bp->b_flags & B_NOREUSE) == 0,
2611 ("brelse: non-VMIO buffer marked NOREUSE"));
2613 if (BUF_LOCKRECURSED(bp)) {
2615 * Do not process, in particular, do not handle the
2616 * B_INVAL/B_RELBUF and do not release to free list.
2622 if (bp->b_flags & B_MANAGED) {
2627 if ((bp->b_vflags & (BV_BKGRDINPROG | BV_BKGRDERR)) == BV_BKGRDERR) {
2628 BO_LOCK(bp->b_bufobj);
2629 bp->b_vflags &= ~BV_BKGRDERR;
2630 BO_UNLOCK(bp->b_bufobj);
2633 if (bp->b_iocmd == BIO_WRITE && (bp->b_ioflags & BIO_ERROR) &&
2634 (bp->b_error != ENXIO || !LIST_EMPTY(&bp->b_dep)) &&
2635 !(bp->b_flags & B_INVAL)) {
2637 * Failed write, redirty. All errors except ENXIO (which
2638 * means the device is gone) are treated as being
2641 * XXX Treating EIO as transient is not correct; the
2642 * contract with the local storage device drivers is that
2643 * they will only return EIO once the I/O is no longer
2644 * retriable. Network I/O also respects this through the
2645 * guarantees of TCP and/or the internal retries of NFS.
2646 * ENOMEM might be transient, but we also have no way of
2647 * knowing when its ok to retry/reschedule. In general,
2648 * this entire case should be made obsolete through better
2649 * error handling/recovery and resource scheduling.
2651 * Do this also for buffers that failed with ENXIO, but have
2652 * non-empty dependencies - the soft updates code might need
2653 * to access the buffer to untangle them.
2655 * Must clear BIO_ERROR to prevent pages from being scrapped.
2657 bp->b_ioflags &= ~BIO_ERROR;
2659 } else if ((bp->b_flags & (B_NOCACHE | B_INVAL)) ||
2660 (bp->b_ioflags & BIO_ERROR) || (bp->b_bufsize <= 0)) {
2662 * Either a failed read I/O, or we were asked to free or not
2663 * cache the buffer, or we failed to write to a device that's
2664 * no longer present.
2666 bp->b_flags |= B_INVAL;
2667 if (!LIST_EMPTY(&bp->b_dep))
2669 if (bp->b_flags & B_DELWRI)
2671 bp->b_flags &= ~(B_DELWRI | B_CACHE);
2672 if ((bp->b_flags & B_VMIO) == 0) {
2680 * We must clear B_RELBUF if B_DELWRI is set. If vfs_vmio_truncate()
2681 * is called with B_DELWRI set, the underlying pages may wind up
2682 * getting freed causing a previous write (bdwrite()) to get 'lost'
2683 * because pages associated with a B_DELWRI bp are marked clean.
2685 * We still allow the B_INVAL case to call vfs_vmio_truncate(), even
2686 * if B_DELWRI is set.
2688 if (bp->b_flags & B_DELWRI)
2689 bp->b_flags &= ~B_RELBUF;
2692 * VMIO buffer rundown. It is not very necessary to keep a VMIO buffer
2693 * constituted, not even NFS buffers now. Two flags effect this. If
2694 * B_INVAL, the struct buf is invalidated but the VM object is kept
2695 * around ( i.e. so it is trivial to reconstitute the buffer later ).
2697 * If BIO_ERROR or B_NOCACHE is set, pages in the VM object will be
2698 * invalidated. BIO_ERROR cannot be set for a failed write unless the
2699 * buffer is also B_INVAL because it hits the re-dirtying code above.
2701 * Normally we can do this whether a buffer is B_DELWRI or not. If
2702 * the buffer is an NFS buffer, it is tracking piecemeal writes or
2703 * the commit state and we cannot afford to lose the buffer. If the
2704 * buffer has a background write in progress, we need to keep it
2705 * around to prevent it from being reconstituted and starting a second
2709 v_mnt = bp->b_vp != NULL ? bp->b_vp->v_mount : NULL;
2711 if ((bp->b_flags & B_VMIO) && (bp->b_flags & B_NOCACHE ||
2712 (bp->b_ioflags & BIO_ERROR && bp->b_iocmd == BIO_READ)) &&
2713 (v_mnt == NULL || (v_mnt->mnt_vfc->vfc_flags & VFCF_NETWORK) == 0 ||
2714 vn_isdisk(bp->b_vp, NULL) || (bp->b_flags & B_DELWRI) == 0)) {
2715 vfs_vmio_invalidate(bp);
2719 if ((bp->b_flags & (B_INVAL | B_RELBUF)) != 0 ||
2720 (bp->b_flags & (B_DELWRI | B_NOREUSE)) == B_NOREUSE) {
2722 bp->b_flags &= ~B_NOREUSE;
2723 if (bp->b_vp != NULL)
2728 * If the buffer has junk contents signal it and eventually
2729 * clean up B_DELWRI and diassociate the vnode so that gbincore()
2732 if (bp->b_bufsize == 0 || (bp->b_ioflags & BIO_ERROR) != 0 ||
2733 (bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF)) != 0)
2734 bp->b_flags |= B_INVAL;
2735 if (bp->b_flags & B_INVAL) {
2736 if (bp->b_flags & B_DELWRI)
2742 buf_track(bp, __func__);
2744 /* buffers with no memory */
2745 if (bp->b_bufsize == 0) {
2749 /* buffers with junk contents */
2750 if (bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF) ||
2751 (bp->b_ioflags & BIO_ERROR)) {
2752 bp->b_xflags &= ~(BX_BKGRDWRITE | BX_ALTDATA);
2753 if (bp->b_vflags & BV_BKGRDINPROG)
2754 panic("losing buffer 2");
2755 qindex = QUEUE_CLEAN;
2756 bp->b_flags |= B_AGE;
2757 /* remaining buffers */
2758 } else if (bp->b_flags & B_DELWRI)
2759 qindex = QUEUE_DIRTY;
2761 qindex = QUEUE_CLEAN;
2763 if ((bp->b_flags & B_DELWRI) == 0 && (bp->b_xflags & BX_VNDIRTY))
2764 panic("brelse: not dirty");
2766 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_RELBUF | B_DIRECT);
2767 /* binsfree unlocks bp. */
2768 binsfree(bp, qindex);
2772 * Release a buffer back to the appropriate queue but do not try to free
2773 * it. The buffer is expected to be used again soon.
2775 * bqrelse() is used by bdwrite() to requeue a delayed write, and used by
2776 * biodone() to requeue an async I/O on completion. It is also used when
2777 * known good buffers need to be requeued but we think we may need the data
2780 * XXX we should be able to leave the B_RELBUF hint set on completion.
2783 bqrelse(struct buf *bp)
2787 CTR3(KTR_BUF, "bqrelse(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
2788 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)),
2789 ("bqrelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp));
2791 qindex = QUEUE_NONE;
2792 if (BUF_LOCKRECURSED(bp)) {
2793 /* do not release to free list */
2797 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF);
2799 if (bp->b_flags & B_MANAGED) {
2800 if (bp->b_flags & B_REMFREE)
2805 /* buffers with stale but valid contents */
2806 if ((bp->b_flags & B_DELWRI) != 0 || (bp->b_vflags & (BV_BKGRDINPROG |
2807 BV_BKGRDERR)) == BV_BKGRDERR) {
2808 BO_LOCK(bp->b_bufobj);
2809 bp->b_vflags &= ~BV_BKGRDERR;
2810 BO_UNLOCK(bp->b_bufobj);
2811 qindex = QUEUE_DIRTY;
2813 if ((bp->b_flags & B_DELWRI) == 0 &&
2814 (bp->b_xflags & BX_VNDIRTY))
2815 panic("bqrelse: not dirty");
2816 if ((bp->b_flags & B_NOREUSE) != 0) {
2820 qindex = QUEUE_CLEAN;
2822 buf_track(bp, __func__);
2823 /* binsfree unlocks bp. */
2824 binsfree(bp, qindex);
2828 buf_track(bp, __func__);
2834 * Complete I/O to a VMIO backed page. Validate the pages as appropriate,
2835 * restore bogus pages.
2838 vfs_vmio_iodone(struct buf *bp)
2844 int i, iosize, resid;
2847 obj = bp->b_bufobj->bo_object;
2848 KASSERT(obj->paging_in_progress >= bp->b_npages,
2849 ("vfs_vmio_iodone: paging in progress(%d) < b_npages(%d)",
2850 obj->paging_in_progress, bp->b_npages));
2853 KASSERT(vp->v_holdcnt > 0,
2854 ("vfs_vmio_iodone: vnode %p has zero hold count", vp));
2855 KASSERT(vp->v_object != NULL,
2856 ("vfs_vmio_iodone: vnode %p has no vm_object", vp));
2858 foff = bp->b_offset;
2859 KASSERT(bp->b_offset != NOOFFSET,
2860 ("vfs_vmio_iodone: bp %p has no buffer offset", bp));
2863 iosize = bp->b_bcount - bp->b_resid;
2864 VM_OBJECT_WLOCK(obj);
2865 for (i = 0; i < bp->b_npages; i++) {
2866 resid = ((foff + PAGE_SIZE) & ~(off_t)PAGE_MASK) - foff;
2871 * cleanup bogus pages, restoring the originals
2874 if (m == bogus_page) {
2876 m = vm_page_lookup(obj, OFF_TO_IDX(foff));
2878 panic("biodone: page disappeared!");
2880 } else if ((bp->b_iocmd == BIO_READ) && resid > 0) {
2882 * In the write case, the valid and clean bits are
2883 * already changed correctly ( see bdwrite() ), so we
2884 * only need to do this here in the read case.
2886 KASSERT((m->dirty & vm_page_bits(foff & PAGE_MASK,
2887 resid)) == 0, ("vfs_vmio_iodone: page %p "
2888 "has unexpected dirty bits", m));
2889 vfs_page_set_valid(bp, foff, m);
2891 KASSERT(OFF_TO_IDX(foff) == m->pindex,
2892 ("vfs_vmio_iodone: foff(%jd)/pindex(%ju) mismatch",
2893 (intmax_t)foff, (uintmax_t)m->pindex));
2896 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK;
2899 vm_object_pip_wakeupn(obj, bp->b_npages);
2900 VM_OBJECT_WUNLOCK(obj);
2901 if (bogus && buf_mapped(bp)) {
2902 BUF_CHECK_MAPPED(bp);
2903 pmap_qenter(trunc_page((vm_offset_t)bp->b_data),
2904 bp->b_pages, bp->b_npages);
2909 * Unwire a page held by a buf and place it on the appropriate vm queue.
2912 vfs_vmio_unwire(struct buf *bp, vm_page_t m)
2917 if (vm_page_unwire_noq(m)) {
2919 * Determine if the page should be freed before adding
2920 * it to the inactive queue.
2922 if (m->valid == 0) {
2923 freed = !vm_page_busied(m);
2926 } else if ((bp->b_flags & B_DIRECT) != 0)
2927 freed = vm_page_try_to_free(m);
2932 * If the page is unlikely to be reused, let the
2933 * VM know. Otherwise, maintain LRU.
2935 if ((bp->b_flags & B_NOREUSE) != 0)
2936 vm_page_deactivate_noreuse(m);
2937 else if (m->queue == PQ_ACTIVE)
2938 vm_page_reference(m);
2940 vm_page_deactivate(m);
2947 * Perform page invalidation when a buffer is released. The fully invalid
2948 * pages will be reclaimed later in vfs_vmio_truncate().
2951 vfs_vmio_invalidate(struct buf *bp)
2955 int i, resid, poffset, presid;
2957 if (buf_mapped(bp)) {
2958 BUF_CHECK_MAPPED(bp);
2959 pmap_qremove(trunc_page((vm_offset_t)bp->b_data), bp->b_npages);
2961 BUF_CHECK_UNMAPPED(bp);
2963 * Get the base offset and length of the buffer. Note that
2964 * in the VMIO case if the buffer block size is not
2965 * page-aligned then b_data pointer may not be page-aligned.
2966 * But our b_pages[] array *IS* page aligned.
2968 * block sizes less then DEV_BSIZE (usually 512) are not
2969 * supported due to the page granularity bits (m->valid,
2970 * m->dirty, etc...).
2972 * See man buf(9) for more information
2974 obj = bp->b_bufobj->bo_object;
2975 resid = bp->b_bufsize;
2976 poffset = bp->b_offset & PAGE_MASK;
2977 VM_OBJECT_WLOCK(obj);
2978 for (i = 0; i < bp->b_npages; i++) {
2980 if (m == bogus_page)
2981 panic("vfs_vmio_invalidate: Unexpected bogus page.");
2982 bp->b_pages[i] = NULL;
2984 presid = resid > (PAGE_SIZE - poffset) ?
2985 (PAGE_SIZE - poffset) : resid;
2986 KASSERT(presid >= 0, ("brelse: extra page"));
2987 while (vm_page_xbusied(m)) {
2989 VM_OBJECT_WUNLOCK(obj);
2990 vm_page_busy_sleep(m, "mbncsh", true);
2991 VM_OBJECT_WLOCK(obj);
2993 if (pmap_page_wired_mappings(m) == 0)
2994 vm_page_set_invalid(m, poffset, presid);
2995 vfs_vmio_unwire(bp, m);
2999 VM_OBJECT_WUNLOCK(obj);
3004 * Page-granular truncation of an existing VMIO buffer.
3007 vfs_vmio_truncate(struct buf *bp, int desiredpages)
3013 if (bp->b_npages == desiredpages)
3016 if (buf_mapped(bp)) {
3017 BUF_CHECK_MAPPED(bp);
3018 pmap_qremove((vm_offset_t)trunc_page((vm_offset_t)bp->b_data) +
3019 (desiredpages << PAGE_SHIFT), bp->b_npages - desiredpages);
3021 BUF_CHECK_UNMAPPED(bp);
3022 obj = bp->b_bufobj->bo_object;
3024 VM_OBJECT_WLOCK(obj);
3025 for (i = desiredpages; i < bp->b_npages; i++) {
3027 KASSERT(m != bogus_page, ("allocbuf: bogus page found"));
3028 bp->b_pages[i] = NULL;
3029 vfs_vmio_unwire(bp, m);
3032 VM_OBJECT_WUNLOCK(obj);
3033 bp->b_npages = desiredpages;
3037 * Byte granular extension of VMIO buffers.
3040 vfs_vmio_extend(struct buf *bp, int desiredpages, int size)
3043 * We are growing the buffer, possibly in a
3044 * byte-granular fashion.
3052 * Step 1, bring in the VM pages from the object, allocating
3053 * them if necessary. We must clear B_CACHE if these pages
3054 * are not valid for the range covered by the buffer.
3056 obj = bp->b_bufobj->bo_object;
3057 VM_OBJECT_WLOCK(obj);
3058 if (bp->b_npages < desiredpages) {
3060 * We must allocate system pages since blocking
3061 * here could interfere with paging I/O, no
3062 * matter which process we are.
3064 * Only exclusive busy can be tested here.
3065 * Blocking on shared busy might lead to
3066 * deadlocks once allocbuf() is called after
3067 * pages are vfs_busy_pages().
3069 (void)vm_page_grab_pages(obj,
3070 OFF_TO_IDX(bp->b_offset) + bp->b_npages,
3071 VM_ALLOC_SYSTEM | VM_ALLOC_IGN_SBUSY |
3072 VM_ALLOC_NOBUSY | VM_ALLOC_WIRED,
3073 &bp->b_pages[bp->b_npages], desiredpages - bp->b_npages);
3074 bp->b_npages = desiredpages;
3078 * Step 2. We've loaded the pages into the buffer,
3079 * we have to figure out if we can still have B_CACHE
3080 * set. Note that B_CACHE is set according to the
3081 * byte-granular range ( bcount and size ), not the
3082 * aligned range ( newbsize ).
3084 * The VM test is against m->valid, which is DEV_BSIZE
3085 * aligned. Needless to say, the validity of the data
3086 * needs to also be DEV_BSIZE aligned. Note that this
3087 * fails with NFS if the server or some other client
3088 * extends the file's EOF. If our buffer is resized,
3089 * B_CACHE may remain set! XXX
3091 toff = bp->b_bcount;
3092 tinc = PAGE_SIZE - ((bp->b_offset + toff) & PAGE_MASK);
3093 while ((bp->b_flags & B_CACHE) && toff < size) {
3096 if (tinc > (size - toff))
3098 pi = ((bp->b_offset & PAGE_MASK) + toff) >> PAGE_SHIFT;
3099 m = bp->b_pages[pi];
3100 vfs_buf_test_cache(bp, bp->b_offset, toff, tinc, m);
3104 VM_OBJECT_WUNLOCK(obj);
3107 * Step 3, fixup the KVA pmap.
3112 BUF_CHECK_UNMAPPED(bp);
3116 * Check to see if a block at a particular lbn is available for a clustered
3120 vfs_bio_clcheck(struct vnode *vp, int size, daddr_t lblkno, daddr_t blkno)
3127 /* If the buf isn't in core skip it */
3128 if ((bpa = gbincore(&vp->v_bufobj, lblkno)) == NULL)
3131 /* If the buf is busy we don't want to wait for it */
3132 if (BUF_LOCK(bpa, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0)
3135 /* Only cluster with valid clusterable delayed write buffers */
3136 if ((bpa->b_flags & (B_DELWRI | B_CLUSTEROK | B_INVAL)) !=
3137 (B_DELWRI | B_CLUSTEROK))
3140 if (bpa->b_bufsize != size)
3144 * Check to see if it is in the expected place on disk and that the
3145 * block has been mapped.
3147 if ((bpa->b_blkno != bpa->b_lblkno) && (bpa->b_blkno == blkno))
3157 * Implement clustered async writes for clearing out B_DELWRI buffers.
3158 * This is much better then the old way of writing only one buffer at
3159 * a time. Note that we may not be presented with the buffers in the
3160 * correct order, so we search for the cluster in both directions.
3163 vfs_bio_awrite(struct buf *bp)
3168 daddr_t lblkno = bp->b_lblkno;
3169 struct vnode *vp = bp->b_vp;
3177 gbflags = (bp->b_data == unmapped_buf) ? GB_UNMAPPED : 0;
3179 * right now we support clustered writing only to regular files. If
3180 * we find a clusterable block we could be in the middle of a cluster
3181 * rather then at the beginning.
3183 if ((vp->v_type == VREG) &&
3184 (vp->v_mount != 0) && /* Only on nodes that have the size info */
3185 (bp->b_flags & (B_CLUSTEROK | B_INVAL)) == B_CLUSTEROK) {
3187 size = vp->v_mount->mnt_stat.f_iosize;
3188 maxcl = MAXPHYS / size;
3191 for (i = 1; i < maxcl; i++)
3192 if (vfs_bio_clcheck(vp, size, lblkno + i,
3193 bp->b_blkno + ((i * size) >> DEV_BSHIFT)) == 0)
3196 for (j = 1; i + j <= maxcl && j <= lblkno; j++)
3197 if (vfs_bio_clcheck(vp, size, lblkno - j,
3198 bp->b_blkno - ((j * size) >> DEV_BSHIFT)) == 0)
3204 * this is a possible cluster write
3208 nwritten = cluster_wbuild(vp, size, lblkno - j, ncl,
3214 bp->b_flags |= B_ASYNC;
3216 * default (old) behavior, writing out only one block
3218 * XXX returns b_bufsize instead of b_bcount for nwritten?
3220 nwritten = bp->b_bufsize;
3229 * Allocate KVA for an empty buf header according to gbflags.
3232 getnewbuf_kva(struct buf *bp, int gbflags, int maxsize)
3235 if ((gbflags & (GB_UNMAPPED | GB_KVAALLOC)) != GB_UNMAPPED) {
3237 * In order to keep fragmentation sane we only allocate kva
3238 * in BKVASIZE chunks. XXX with vmem we can do page size.
3240 maxsize = (maxsize + BKVAMASK) & ~BKVAMASK;
3242 if (maxsize != bp->b_kvasize &&
3243 bufkva_alloc(bp, maxsize, gbflags))
3252 * Find and initialize a new buffer header, freeing up existing buffers
3253 * in the bufqueues as necessary. The new buffer is returned locked.
3256 * We have insufficient buffer headers
3257 * We have insufficient buffer space
3258 * buffer_arena is too fragmented ( space reservation fails )
3259 * If we have to flush dirty buffers ( but we try to avoid this )
3261 * The caller is responsible for releasing the reserved bufspace after
3262 * allocbuf() is called.
3265 getnewbuf(struct vnode *vp, int slpflag, int slptimeo, int maxsize, int gbflags)
3267 struct bufdomain *bd;
3269 bool metadata, reserved;
3272 KASSERT((gbflags & (GB_UNMAPPED | GB_KVAALLOC)) != GB_KVAALLOC,
3273 ("GB_KVAALLOC only makes sense with GB_UNMAPPED"));
3274 if (!unmapped_buf_allowed)
3275 gbflags &= ~(GB_UNMAPPED | GB_KVAALLOC);
3277 if (vp == NULL || (vp->v_vflag & (VV_MD | VV_SYSTEM)) != 0 ||
3285 bd = &bdomain[vp->v_bufobj.bo_domain];
3287 counter_u64_add(getnewbufcalls, 1);
3290 if (reserved == false &&
3291 bufspace_reserve(bd, maxsize, metadata) != 0) {
3292 counter_u64_add(getnewbufrestarts, 1);
3296 if ((bp = buf_alloc(bd)) == NULL) {
3297 counter_u64_add(getnewbufrestarts, 1);
3300 if (getnewbuf_kva(bp, gbflags, maxsize) == 0)
3303 } while (buf_recycle(bd, false) == 0);
3306 bufspace_release(bd, maxsize);
3308 bp->b_flags |= B_INVAL;
3311 bufspace_wait(bd, vp, gbflags, slpflag, slptimeo);
3319 * buffer flushing daemon. Buffers are normally flushed by the
3320 * update daemon but if it cannot keep up this process starts to
3321 * take the load in an attempt to prevent getnewbuf() from blocking.
3323 static struct kproc_desc buf_kp = {
3328 SYSINIT(bufdaemon, SI_SUB_KTHREAD_BUF, SI_ORDER_FIRST, kproc_start, &buf_kp);
3331 buf_flush(struct vnode *vp, struct bufdomain *bd, int target)
3335 flushed = flushbufqueues(vp, bd, target, 0);
3338 * Could not find any buffers without rollback
3339 * dependencies, so just write the first one
3340 * in the hopes of eventually making progress.
3342 if (vp != NULL && target > 2)
3344 flushbufqueues(vp, bd, target, 1);
3352 struct bufdomain *bd;
3358 * This process needs to be suspended prior to shutdown sync.
3360 EVENTHANDLER_REGISTER(shutdown_pre_sync, kproc_shutdown, bufdaemonproc,
3364 * Start the buf clean daemons as children threads.
3366 for (i = 0 ; i < buf_domains; i++) {
3369 error = kthread_add((void (*)(void *))bufspace_daemon,
3370 &bdomain[i], curproc, NULL, 0, 0, "bufspacedaemon-%d", i);
3372 panic("error %d spawning bufspace daemon", error);
3376 * This process is allowed to take the buffer cache to the limit
3378 curthread->td_pflags |= TDP_NORUNNINGBUF | TDP_BUFNEED;
3382 mtx_unlock(&bdlock);
3384 kproc_suspend_check(bufdaemonproc);
3387 * Save speedupreq for this pass and reset to capture new
3390 speedupreq = bd_speedupreq;
3394 * Flush each domain sequentially according to its level and
3395 * the speedup request.
3397 for (i = 0; i < buf_domains; i++) {
3400 lodirty = bd->bd_numdirtybuffers / 2;
3402 lodirty = bd->bd_lodirtybuffers;
3403 while (bd->bd_numdirtybuffers > lodirty) {
3404 if (buf_flush(NULL, bd,
3405 bd->bd_numdirtybuffers - lodirty) == 0)
3407 kern_yield(PRI_USER);
3412 * Only clear bd_request if we have reached our low water
3413 * mark. The buf_daemon normally waits 1 second and
3414 * then incrementally flushes any dirty buffers that have
3415 * built up, within reason.
3417 * If we were unable to hit our low water mark and couldn't
3418 * find any flushable buffers, we sleep for a short period
3419 * to avoid endless loops on unlockable buffers.
3422 if (!BIT_EMPTY(BUF_DOMAINS, &bdlodirty)) {
3424 * We reached our low water mark, reset the
3425 * request and sleep until we are needed again.
3426 * The sleep is just so the suspend code works.
3430 * Do an extra wakeup in case dirty threshold
3431 * changed via sysctl and the explicit transition
3432 * out of shortfall was missed.
3435 if (runningbufspace <= lorunningspace)
3437 msleep(&bd_request, &bdlock, PVM, "psleep", hz);
3440 * We couldn't find any flushable dirty buffers but
3441 * still have too many dirty buffers, we
3442 * have to sleep and try again. (rare)
3444 msleep(&bd_request, &bdlock, PVM, "qsleep", hz / 10);
3452 * Try to flush a buffer in the dirty queue. We must be careful to
3453 * free up B_INVAL buffers instead of write them, which NFS is
3454 * particularly sensitive to.
3456 static int flushwithdeps = 0;
3457 SYSCTL_INT(_vfs, OID_AUTO, flushwithdeps, CTLFLAG_RW, &flushwithdeps,
3458 0, "Number of buffers flushed with dependecies that require rollbacks");
3461 flushbufqueues(struct vnode *lvp, struct bufdomain *bd, int target,
3464 struct bufqueue *bq;
3465 struct buf *sentinel;
3475 bq = &bd->bd_dirtyq;
3477 sentinel = malloc(sizeof(struct buf), M_TEMP, M_WAITOK | M_ZERO);
3478 sentinel->b_qindex = QUEUE_SENTINEL;
3480 TAILQ_INSERT_HEAD(&bq->bq_queue, sentinel, b_freelist);
3482 while (flushed != target) {
3485 bp = TAILQ_NEXT(sentinel, b_freelist);
3487 TAILQ_REMOVE(&bq->bq_queue, sentinel, b_freelist);
3488 TAILQ_INSERT_AFTER(&bq->bq_queue, bp, sentinel,
3495 * Skip sentinels inserted by other invocations of the
3496 * flushbufqueues(), taking care to not reorder them.
3498 * Only flush the buffers that belong to the
3499 * vnode locked by the curthread.
3501 if (bp->b_qindex == QUEUE_SENTINEL || (lvp != NULL &&
3506 error = BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL);
3512 * BKGRDINPROG can only be set with the buf and bufobj
3513 * locks both held. We tolerate a race to clear it here.
3515 if ((bp->b_vflags & BV_BKGRDINPROG) != 0 ||
3516 (bp->b_flags & B_DELWRI) == 0) {
3520 if (bp->b_flags & B_INVAL) {
3527 if (!LIST_EMPTY(&bp->b_dep) && buf_countdeps(bp, 0)) {
3528 if (flushdeps == 0) {
3536 * We must hold the lock on a vnode before writing
3537 * one of its buffers. Otherwise we may confuse, or
3538 * in the case of a snapshot vnode, deadlock the
3541 * The lock order here is the reverse of the normal
3542 * of vnode followed by buf lock. This is ok because
3543 * the NOWAIT will prevent deadlock.
3546 if (vn_start_write(vp, &mp, V_NOWAIT) != 0) {
3552 error = vn_lock(vp, LK_EXCLUSIVE | LK_NOWAIT);
3554 ASSERT_VOP_LOCKED(vp, "getbuf");
3556 error = VOP_ISLOCKED(vp) == LK_EXCLUSIVE ? 0 :
3557 vn_lock(vp, LK_TRYUPGRADE);
3560 CTR3(KTR_BUF, "flushbufqueue(%p) vp %p flags %X",
3561 bp, bp->b_vp, bp->b_flags);
3562 if (curproc == bufdaemonproc) {
3567 counter_u64_add(notbufdflushes, 1);
3569 vn_finished_write(mp);
3572 flushwithdeps += hasdeps;
3576 * Sleeping on runningbufspace while holding
3577 * vnode lock leads to deadlock.
3579 if (curproc == bufdaemonproc &&
3580 runningbufspace > hirunningspace)
3581 waitrunningbufspace();
3584 vn_finished_write(mp);
3588 TAILQ_REMOVE(&bq->bq_queue, sentinel, b_freelist);
3590 free(sentinel, M_TEMP);
3595 * Check to see if a block is currently memory resident.
3598 incore(struct bufobj *bo, daddr_t blkno)
3603 bp = gbincore(bo, blkno);
3609 * Returns true if no I/O is needed to access the
3610 * associated VM object. This is like incore except
3611 * it also hunts around in the VM system for the data.
3615 inmem(struct vnode * vp, daddr_t blkno)
3618 vm_offset_t toff, tinc, size;
3622 ASSERT_VOP_LOCKED(vp, "inmem");
3624 if (incore(&vp->v_bufobj, blkno))
3626 if (vp->v_mount == NULL)
3633 if (size > vp->v_mount->mnt_stat.f_iosize)
3634 size = vp->v_mount->mnt_stat.f_iosize;
3635 off = (vm_ooffset_t)blkno * (vm_ooffset_t)vp->v_mount->mnt_stat.f_iosize;
3637 VM_OBJECT_RLOCK(obj);
3638 for (toff = 0; toff < vp->v_mount->mnt_stat.f_iosize; toff += tinc) {
3639 m = vm_page_lookup(obj, OFF_TO_IDX(off + toff));
3643 if (tinc > PAGE_SIZE - ((toff + off) & PAGE_MASK))
3644 tinc = PAGE_SIZE - ((toff + off) & PAGE_MASK);
3645 if (vm_page_is_valid(m,
3646 (vm_offset_t) ((toff + off) & PAGE_MASK), tinc) == 0)
3649 VM_OBJECT_RUNLOCK(obj);
3653 VM_OBJECT_RUNLOCK(obj);
3658 * Set the dirty range for a buffer based on the status of the dirty
3659 * bits in the pages comprising the buffer. The range is limited
3660 * to the size of the buffer.
3662 * Tell the VM system that the pages associated with this buffer
3663 * are clean. This is used for delayed writes where the data is
3664 * going to go to disk eventually without additional VM intevention.
3666 * Note that while we only really need to clean through to b_bcount, we
3667 * just go ahead and clean through to b_bufsize.
3670 vfs_clean_pages_dirty_buf(struct buf *bp)
3672 vm_ooffset_t foff, noff, eoff;
3676 if ((bp->b_flags & B_VMIO) == 0 || bp->b_bufsize == 0)
3679 foff = bp->b_offset;
3680 KASSERT(bp->b_offset != NOOFFSET,
3681 ("vfs_clean_pages_dirty_buf: no buffer offset"));
3683 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object);
3684 vfs_drain_busy_pages(bp);
3685 vfs_setdirty_locked_object(bp);
3686 for (i = 0; i < bp->b_npages; i++) {
3687 noff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK;
3689 if (eoff > bp->b_offset + bp->b_bufsize)
3690 eoff = bp->b_offset + bp->b_bufsize;
3692 vfs_page_set_validclean(bp, foff, m);
3693 /* vm_page_clear_dirty(m, foff & PAGE_MASK, eoff - foff); */
3696 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object);
3700 vfs_setdirty_locked_object(struct buf *bp)
3705 object = bp->b_bufobj->bo_object;
3706 VM_OBJECT_ASSERT_WLOCKED(object);
3709 * We qualify the scan for modified pages on whether the
3710 * object has been flushed yet.
3712 if ((object->flags & OBJ_MIGHTBEDIRTY) != 0) {
3713 vm_offset_t boffset;
3714 vm_offset_t eoffset;
3717 * test the pages to see if they have been modified directly
3718 * by users through the VM system.
3720 for (i = 0; i < bp->b_npages; i++)
3721 vm_page_test_dirty(bp->b_pages[i]);
3724 * Calculate the encompassing dirty range, boffset and eoffset,
3725 * (eoffset - boffset) bytes.
3728 for (i = 0; i < bp->b_npages; i++) {
3729 if (bp->b_pages[i]->dirty)
3732 boffset = (i << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK);
3734 for (i = bp->b_npages - 1; i >= 0; --i) {
3735 if (bp->b_pages[i]->dirty) {
3739 eoffset = ((i + 1) << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK);
3742 * Fit it to the buffer.
3745 if (eoffset > bp->b_bcount)
3746 eoffset = bp->b_bcount;
3749 * If we have a good dirty range, merge with the existing
3753 if (boffset < eoffset) {
3754 if (bp->b_dirtyoff > boffset)
3755 bp->b_dirtyoff = boffset;
3756 if (bp->b_dirtyend < eoffset)
3757 bp->b_dirtyend = eoffset;
3763 * Allocate the KVA mapping for an existing buffer.
3764 * If an unmapped buffer is provided but a mapped buffer is requested, take
3765 * also care to properly setup mappings between pages and KVA.
3768 bp_unmapped_get_kva(struct buf *bp, daddr_t blkno, int size, int gbflags)
3770 int bsize, maxsize, need_mapping, need_kva;
3773 need_mapping = bp->b_data == unmapped_buf &&
3774 (gbflags & GB_UNMAPPED) == 0;
3775 need_kva = bp->b_kvabase == unmapped_buf &&
3776 bp->b_data == unmapped_buf &&
3777 (gbflags & GB_KVAALLOC) != 0;
3778 if (!need_mapping && !need_kva)
3781 BUF_CHECK_UNMAPPED(bp);
3783 if (need_mapping && bp->b_kvabase != unmapped_buf) {
3785 * Buffer is not mapped, but the KVA was already
3786 * reserved at the time of the instantiation. Use the
3793 * Calculate the amount of the address space we would reserve
3794 * if the buffer was mapped.
3796 bsize = vn_isdisk(bp->b_vp, NULL) ? DEV_BSIZE : bp->b_bufobj->bo_bsize;
3797 KASSERT(bsize != 0, ("bsize == 0, check bo->bo_bsize"));
3798 offset = blkno * bsize;
3799 maxsize = size + (offset & PAGE_MASK);
3800 maxsize = imax(maxsize, bsize);
3802 while (bufkva_alloc(bp, maxsize, gbflags) != 0) {
3803 if ((gbflags & GB_NOWAIT_BD) != 0) {
3805 * XXXKIB: defragmentation cannot
3806 * succeed, not sure what else to do.
3808 panic("GB_NOWAIT_BD and GB_UNMAPPED %p", bp);
3810 counter_u64_add(mappingrestarts, 1);
3811 bufspace_wait(bufdomain(bp), bp->b_vp, gbflags, 0, 0);
3815 /* b_offset is handled by bpmap_qenter. */
3816 bp->b_data = bp->b_kvabase;
3817 BUF_CHECK_MAPPED(bp);
3825 * Get a block given a specified block and offset into a file/device.
3826 * The buffers B_DONE bit will be cleared on return, making it almost
3827 * ready for an I/O initiation. B_INVAL may or may not be set on
3828 * return. The caller should clear B_INVAL prior to initiating a
3831 * For a non-VMIO buffer, B_CACHE is set to the opposite of B_INVAL for
3832 * an existing buffer.
3834 * For a VMIO buffer, B_CACHE is modified according to the backing VM.
3835 * If getblk()ing a previously 0-sized invalid buffer, B_CACHE is set
3836 * and then cleared based on the backing VM. If the previous buffer is
3837 * non-0-sized but invalid, B_CACHE will be cleared.
3839 * If getblk() must create a new buffer, the new buffer is returned with
3840 * both B_INVAL and B_CACHE clear unless it is a VMIO buffer, in which
3841 * case it is returned with B_INVAL clear and B_CACHE set based on the
3844 * getblk() also forces a bwrite() for any B_DELWRI buffer whos
3845 * B_CACHE bit is clear.
3847 * What this means, basically, is that the caller should use B_CACHE to
3848 * determine whether the buffer is fully valid or not and should clear
3849 * B_INVAL prior to issuing a read. If the caller intends to validate
3850 * the buffer by loading its data area with something, the caller needs
3851 * to clear B_INVAL. If the caller does this without issuing an I/O,
3852 * the caller should set B_CACHE ( as an optimization ), else the caller
3853 * should issue the I/O and biodone() will set B_CACHE if the I/O was
3854 * a write attempt or if it was a successful read. If the caller
3855 * intends to issue a READ, the caller must clear B_INVAL and BIO_ERROR
3856 * prior to issuing the READ. biodone() will *not* clear B_INVAL.
3859 getblk(struct vnode *vp, daddr_t blkno, int size, int slpflag, int slptimeo,
3864 int bsize, error, maxsize, vmio;
3867 CTR3(KTR_BUF, "getblk(%p, %ld, %d)", vp, (long)blkno, size);
3868 KASSERT((flags & (GB_UNMAPPED | GB_KVAALLOC)) != GB_KVAALLOC,
3869 ("GB_KVAALLOC only makes sense with GB_UNMAPPED"));
3870 ASSERT_VOP_LOCKED(vp, "getblk");
3871 if (size > maxbcachebuf)
3872 panic("getblk: size(%d) > maxbcachebuf(%d)\n", size,
3874 if (!unmapped_buf_allowed)
3875 flags &= ~(GB_UNMAPPED | GB_KVAALLOC);
3880 bp = gbincore(bo, blkno);
3884 * Buffer is in-core. If the buffer is not busy nor managed,
3885 * it must be on a queue.
3887 lockflags = LK_EXCLUSIVE | LK_SLEEPFAIL | LK_INTERLOCK;
3889 if (flags & GB_LOCK_NOWAIT)
3890 lockflags |= LK_NOWAIT;
3892 error = BUF_TIMELOCK(bp, lockflags,
3893 BO_LOCKPTR(bo), "getblk", slpflag, slptimeo);
3896 * If we slept and got the lock we have to restart in case
3897 * the buffer changed identities.
3899 if (error == ENOLCK)
3901 /* We timed out or were interrupted. */
3904 /* If recursed, assume caller knows the rules. */
3905 else if (BUF_LOCKRECURSED(bp))
3909 * The buffer is locked. B_CACHE is cleared if the buffer is
3910 * invalid. Otherwise, for a non-VMIO buffer, B_CACHE is set
3911 * and for a VMIO buffer B_CACHE is adjusted according to the
3914 if (bp->b_flags & B_INVAL)
3915 bp->b_flags &= ~B_CACHE;
3916 else if ((bp->b_flags & (B_VMIO | B_INVAL)) == 0)
3917 bp->b_flags |= B_CACHE;
3918 if (bp->b_flags & B_MANAGED)
3919 MPASS(bp->b_qindex == QUEUE_NONE);
3924 * check for size inconsistencies for non-VMIO case.
3926 if (bp->b_bcount != size) {
3927 if ((bp->b_flags & B_VMIO) == 0 ||
3928 (size > bp->b_kvasize)) {
3929 if (bp->b_flags & B_DELWRI) {
3930 bp->b_flags |= B_NOCACHE;
3933 if (LIST_EMPTY(&bp->b_dep)) {
3934 bp->b_flags |= B_RELBUF;
3937 bp->b_flags |= B_NOCACHE;
3946 * Handle the case of unmapped buffer which should
3947 * become mapped, or the buffer for which KVA
3948 * reservation is requested.
3950 bp_unmapped_get_kva(bp, blkno, size, flags);
3953 * If the size is inconsistent in the VMIO case, we can resize
3954 * the buffer. This might lead to B_CACHE getting set or
3955 * cleared. If the size has not changed, B_CACHE remains
3956 * unchanged from its previous state.
3960 KASSERT(bp->b_offset != NOOFFSET,
3961 ("getblk: no buffer offset"));
3964 * A buffer with B_DELWRI set and B_CACHE clear must
3965 * be committed before we can return the buffer in
3966 * order to prevent the caller from issuing a read
3967 * ( due to B_CACHE not being set ) and overwriting
3970 * Most callers, including NFS and FFS, need this to
3971 * operate properly either because they assume they
3972 * can issue a read if B_CACHE is not set, or because
3973 * ( for example ) an uncached B_DELWRI might loop due
3974 * to softupdates re-dirtying the buffer. In the latter
3975 * case, B_CACHE is set after the first write completes,
3976 * preventing further loops.
3977 * NOTE! b*write() sets B_CACHE. If we cleared B_CACHE
3978 * above while extending the buffer, we cannot allow the
3979 * buffer to remain with B_CACHE set after the write
3980 * completes or it will represent a corrupt state. To
3981 * deal with this we set B_NOCACHE to scrap the buffer
3984 * We might be able to do something fancy, like setting
3985 * B_CACHE in bwrite() except if B_DELWRI is already set,
3986 * so the below call doesn't set B_CACHE, but that gets real
3987 * confusing. This is much easier.
3990 if ((bp->b_flags & (B_CACHE|B_DELWRI)) == B_DELWRI) {
3991 bp->b_flags |= B_NOCACHE;
3995 bp->b_flags &= ~B_DONE;
3998 * Buffer is not in-core, create new buffer. The buffer
3999 * returned by getnewbuf() is locked. Note that the returned
4000 * buffer is also considered valid (not marked B_INVAL).
4004 * If the user does not want us to create the buffer, bail out
4007 if (flags & GB_NOCREAT)
4009 if (bdomain[bo->bo_domain].bd_freebuffers == 0 &&
4010 TD_IS_IDLETHREAD(curthread))
4013 bsize = vn_isdisk(vp, NULL) ? DEV_BSIZE : bo->bo_bsize;
4014 KASSERT(bsize != 0, ("bsize == 0, check bo->bo_bsize"));
4015 offset = blkno * bsize;
4016 vmio = vp->v_object != NULL;
4018 maxsize = size + (offset & PAGE_MASK);
4021 /* Do not allow non-VMIO notmapped buffers. */
4022 flags &= ~(GB_UNMAPPED | GB_KVAALLOC);
4024 maxsize = imax(maxsize, bsize);
4026 bp = getnewbuf(vp, slpflag, slptimeo, maxsize, flags);
4028 if (slpflag || slptimeo)
4031 * XXX This is here until the sleep path is diagnosed
4032 * enough to work under very low memory conditions.
4034 * There's an issue on low memory, 4BSD+non-preempt
4035 * systems (eg MIPS routers with 32MB RAM) where buffer
4036 * exhaustion occurs without sleeping for buffer
4037 * reclaimation. This just sticks in a loop and
4038 * constantly attempts to allocate a buffer, which
4039 * hits exhaustion and tries to wakeup bufdaemon.
4040 * This never happens because we never yield.
4042 * The real solution is to identify and fix these cases
4043 * so we aren't effectively busy-waiting in a loop
4044 * until the reclaimation path has cycles to run.
4046 kern_yield(PRI_USER);
4051 * This code is used to make sure that a buffer is not
4052 * created while the getnewbuf routine is blocked.
4053 * This can be a problem whether the vnode is locked or not.
4054 * If the buffer is created out from under us, we have to
4055 * throw away the one we just created.
4057 * Note: this must occur before we associate the buffer
4058 * with the vp especially considering limitations in
4059 * the splay tree implementation when dealing with duplicate
4063 if (gbincore(bo, blkno)) {
4065 bp->b_flags |= B_INVAL;
4066 bufspace_release(bufdomain(bp), maxsize);
4072 * Insert the buffer into the hash, so that it can
4073 * be found by incore.
4075 bp->b_blkno = bp->b_lblkno = blkno;
4076 bp->b_offset = offset;
4081 * set B_VMIO bit. allocbuf() the buffer bigger. Since the
4082 * buffer size starts out as 0, B_CACHE will be set by
4083 * allocbuf() for the VMIO case prior to it testing the
4084 * backing store for validity.
4088 bp->b_flags |= B_VMIO;
4089 KASSERT(vp->v_object == bp->b_bufobj->bo_object,
4090 ("ARGH! different b_bufobj->bo_object %p %p %p\n",
4091 bp, vp->v_object, bp->b_bufobj->bo_object));
4093 bp->b_flags &= ~B_VMIO;
4094 KASSERT(bp->b_bufobj->bo_object == NULL,
4095 ("ARGH! has b_bufobj->bo_object %p %p\n",
4096 bp, bp->b_bufobj->bo_object));
4097 BUF_CHECK_MAPPED(bp);
4101 bufspace_release(bufdomain(bp), maxsize);
4102 bp->b_flags &= ~B_DONE;
4104 CTR4(KTR_BUF, "getblk(%p, %ld, %d) = %p", vp, (long)blkno, size, bp);
4105 BUF_ASSERT_HELD(bp);
4107 buf_track(bp, __func__);
4108 KASSERT(bp->b_bufobj == bo,
4109 ("bp %p wrong b_bufobj %p should be %p", bp, bp->b_bufobj, bo));
4114 * Get an empty, disassociated buffer of given size. The buffer is initially
4118 geteblk(int size, int flags)
4123 maxsize = (size + BKVAMASK) & ~BKVAMASK;
4124 while ((bp = getnewbuf(NULL, 0, 0, maxsize, flags)) == NULL) {
4125 if ((flags & GB_NOWAIT_BD) &&
4126 (curthread->td_pflags & TDP_BUFNEED) != 0)
4130 bufspace_release(bufdomain(bp), maxsize);
4131 bp->b_flags |= B_INVAL; /* b_dep cleared by getnewbuf() */
4132 BUF_ASSERT_HELD(bp);
4137 * Truncate the backing store for a non-vmio buffer.
4140 vfs_nonvmio_truncate(struct buf *bp, int newbsize)
4143 if (bp->b_flags & B_MALLOC) {
4145 * malloced buffers are not shrunk
4147 if (newbsize == 0) {
4148 bufmallocadjust(bp, 0);
4149 free(bp->b_data, M_BIOBUF);
4150 bp->b_data = bp->b_kvabase;
4151 bp->b_flags &= ~B_MALLOC;
4155 vm_hold_free_pages(bp, newbsize);
4156 bufspace_adjust(bp, newbsize);
4160 * Extend the backing for a non-VMIO buffer.
4163 vfs_nonvmio_extend(struct buf *bp, int newbsize)
4169 * We only use malloced memory on the first allocation.
4170 * and revert to page-allocated memory when the buffer
4173 * There is a potential smp race here that could lead
4174 * to bufmallocspace slightly passing the max. It
4175 * is probably extremely rare and not worth worrying
4178 if (bp->b_bufsize == 0 && newbsize <= PAGE_SIZE/2 &&
4179 bufmallocspace < maxbufmallocspace) {
4180 bp->b_data = malloc(newbsize, M_BIOBUF, M_WAITOK);
4181 bp->b_flags |= B_MALLOC;
4182 bufmallocadjust(bp, newbsize);
4187 * If the buffer is growing on its other-than-first
4188 * allocation then we revert to the page-allocation
4193 if (bp->b_flags & B_MALLOC) {
4194 origbuf = bp->b_data;
4195 origbufsize = bp->b_bufsize;
4196 bp->b_data = bp->b_kvabase;
4197 bufmallocadjust(bp, 0);
4198 bp->b_flags &= ~B_MALLOC;
4199 newbsize = round_page(newbsize);
4201 vm_hold_load_pages(bp, (vm_offset_t) bp->b_data + bp->b_bufsize,
4202 (vm_offset_t) bp->b_data + newbsize);
4203 if (origbuf != NULL) {
4204 bcopy(origbuf, bp->b_data, origbufsize);
4205 free(origbuf, M_BIOBUF);
4207 bufspace_adjust(bp, newbsize);
4211 * This code constitutes the buffer memory from either anonymous system
4212 * memory (in the case of non-VMIO operations) or from an associated
4213 * VM object (in the case of VMIO operations). This code is able to
4214 * resize a buffer up or down.
4216 * Note that this code is tricky, and has many complications to resolve
4217 * deadlock or inconsistent data situations. Tread lightly!!!
4218 * There are B_CACHE and B_DELWRI interactions that must be dealt with by
4219 * the caller. Calling this code willy nilly can result in the loss of data.
4221 * allocbuf() only adjusts B_CACHE for VMIO buffers. getblk() deals with
4222 * B_CACHE for the non-VMIO case.
4225 allocbuf(struct buf *bp, int size)
4229 BUF_ASSERT_HELD(bp);
4231 if (bp->b_bcount == size)
4234 if (bp->b_kvasize != 0 && bp->b_kvasize < size)
4235 panic("allocbuf: buffer too small");
4237 newbsize = roundup2(size, DEV_BSIZE);
4238 if ((bp->b_flags & B_VMIO) == 0) {
4239 if ((bp->b_flags & B_MALLOC) == 0)
4240 newbsize = round_page(newbsize);
4242 * Just get anonymous memory from the kernel. Don't
4243 * mess with B_CACHE.
4245 if (newbsize < bp->b_bufsize)
4246 vfs_nonvmio_truncate(bp, newbsize);
4247 else if (newbsize > bp->b_bufsize)
4248 vfs_nonvmio_extend(bp, newbsize);
4252 desiredpages = (size == 0) ? 0 :
4253 num_pages((bp->b_offset & PAGE_MASK) + newbsize);
4255 if (bp->b_flags & B_MALLOC)
4256 panic("allocbuf: VMIO buffer can't be malloced");
4258 * Set B_CACHE initially if buffer is 0 length or will become
4261 if (size == 0 || bp->b_bufsize == 0)
4262 bp->b_flags |= B_CACHE;
4264 if (newbsize < bp->b_bufsize)
4265 vfs_vmio_truncate(bp, desiredpages);
4266 /* XXX This looks as if it should be newbsize > b_bufsize */
4267 else if (size > bp->b_bcount)
4268 vfs_vmio_extend(bp, desiredpages, size);
4269 bufspace_adjust(bp, newbsize);
4271 bp->b_bcount = size; /* requested buffer size. */
4275 extern int inflight_transient_maps;
4278 biodone(struct bio *bp)
4281 void (*done)(struct bio *);
4282 vm_offset_t start, end;
4284 biotrack(bp, __func__);
4285 if ((bp->bio_flags & BIO_TRANSIENT_MAPPING) != 0) {
4286 bp->bio_flags &= ~BIO_TRANSIENT_MAPPING;
4287 bp->bio_flags |= BIO_UNMAPPED;
4288 start = trunc_page((vm_offset_t)bp->bio_data);
4289 end = round_page((vm_offset_t)bp->bio_data + bp->bio_length);
4290 bp->bio_data = unmapped_buf;
4291 pmap_qremove(start, atop(end - start));
4292 vmem_free(transient_arena, start, end - start);
4293 atomic_add_int(&inflight_transient_maps, -1);
4295 done = bp->bio_done;
4297 mtxp = mtx_pool_find(mtxpool_sleep, bp);
4299 bp->bio_flags |= BIO_DONE;
4307 * Wait for a BIO to finish.
4310 biowait(struct bio *bp, const char *wchan)
4314 mtxp = mtx_pool_find(mtxpool_sleep, bp);
4316 while ((bp->bio_flags & BIO_DONE) == 0)
4317 msleep(bp, mtxp, PRIBIO, wchan, 0);
4319 if (bp->bio_error != 0)
4320 return (bp->bio_error);
4321 if (!(bp->bio_flags & BIO_ERROR))
4327 biofinish(struct bio *bp, struct devstat *stat, int error)
4331 bp->bio_error = error;
4332 bp->bio_flags |= BIO_ERROR;
4335 devstat_end_transaction_bio(stat, bp);
4339 #if defined(BUF_TRACKING) || defined(FULL_BUF_TRACKING)
4341 biotrack_buf(struct bio *bp, const char *location)
4344 buf_track(bp->bio_track_bp, location);
4351 * Wait for buffer I/O completion, returning error status. The buffer
4352 * is left locked and B_DONE on return. B_EINTR is converted into an EINTR
4353 * error and cleared.
4356 bufwait(struct buf *bp)
4358 if (bp->b_iocmd == BIO_READ)
4359 bwait(bp, PRIBIO, "biord");
4361 bwait(bp, PRIBIO, "biowr");
4362 if (bp->b_flags & B_EINTR) {
4363 bp->b_flags &= ~B_EINTR;
4366 if (bp->b_ioflags & BIO_ERROR) {
4367 return (bp->b_error ? bp->b_error : EIO);
4376 * Finish I/O on a buffer, optionally calling a completion function.
4377 * This is usually called from an interrupt so process blocking is
4380 * biodone is also responsible for setting B_CACHE in a B_VMIO bp.
4381 * In a non-VMIO bp, B_CACHE will be set on the next getblk()
4382 * assuming B_INVAL is clear.
4384 * For the VMIO case, we set B_CACHE if the op was a read and no
4385 * read error occurred, or if the op was a write. B_CACHE is never
4386 * set if the buffer is invalid or otherwise uncacheable.
4388 * biodone does not mess with B_INVAL, allowing the I/O routine or the
4389 * initiator to leave B_INVAL set to brelse the buffer out of existence
4390 * in the biodone routine.
4393 bufdone(struct buf *bp)
4395 struct bufobj *dropobj;
4396 void (*biodone)(struct buf *);
4398 buf_track(bp, __func__);
4399 CTR3(KTR_BUF, "bufdone(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
4402 KASSERT(!(bp->b_flags & B_DONE), ("biodone: bp %p already done", bp));
4403 BUF_ASSERT_HELD(bp);
4405 runningbufwakeup(bp);
4406 if (bp->b_iocmd == BIO_WRITE)
4407 dropobj = bp->b_bufobj;
4408 /* call optional completion function if requested */
4409 if (bp->b_iodone != NULL) {
4410 biodone = bp->b_iodone;
4411 bp->b_iodone = NULL;
4414 bufobj_wdrop(dropobj);
4417 if (bp->b_flags & B_VMIO) {
4419 * Set B_CACHE if the op was a normal read and no error
4420 * occurred. B_CACHE is set for writes in the b*write()
4423 if (bp->b_iocmd == BIO_READ &&
4424 !(bp->b_flags & (B_INVAL|B_NOCACHE)) &&
4425 !(bp->b_ioflags & BIO_ERROR))
4426 bp->b_flags |= B_CACHE;
4427 vfs_vmio_iodone(bp);
4429 if (!LIST_EMPTY(&bp->b_dep))
4431 if ((bp->b_flags & B_CKHASH) != 0) {
4432 KASSERT(bp->b_iocmd == BIO_READ,
4433 ("bufdone: b_iocmd %d not BIO_READ", bp->b_iocmd));
4434 KASSERT(buf_mapped(bp), ("bufdone: bp %p not mapped", bp));
4435 (*bp->b_ckhashcalc)(bp);
4438 * For asynchronous completions, release the buffer now. The brelse
4439 * will do a wakeup there if necessary - so no need to do a wakeup
4440 * here in the async case. The sync case always needs to do a wakeup.
4442 if (bp->b_flags & B_ASYNC) {
4443 if ((bp->b_flags & (B_NOCACHE | B_INVAL | B_RELBUF)) ||
4444 (bp->b_ioflags & BIO_ERROR))
4451 bufobj_wdrop(dropobj);
4455 * This routine is called in lieu of iodone in the case of
4456 * incomplete I/O. This keeps the busy status for pages
4460 vfs_unbusy_pages(struct buf *bp)
4466 runningbufwakeup(bp);
4467 if (!(bp->b_flags & B_VMIO))
4470 obj = bp->b_bufobj->bo_object;
4471 VM_OBJECT_WLOCK(obj);
4472 for (i = 0; i < bp->b_npages; i++) {
4474 if (m == bogus_page) {
4475 m = vm_page_lookup(obj, OFF_TO_IDX(bp->b_offset) + i);
4477 panic("vfs_unbusy_pages: page missing\n");
4479 if (buf_mapped(bp)) {
4480 BUF_CHECK_MAPPED(bp);
4481 pmap_qenter(trunc_page((vm_offset_t)bp->b_data),
4482 bp->b_pages, bp->b_npages);
4484 BUF_CHECK_UNMAPPED(bp);
4488 vm_object_pip_wakeupn(obj, bp->b_npages);
4489 VM_OBJECT_WUNLOCK(obj);
4493 * vfs_page_set_valid:
4495 * Set the valid bits in a page based on the supplied offset. The
4496 * range is restricted to the buffer's size.
4498 * This routine is typically called after a read completes.
4501 vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, vm_page_t m)
4506 * Compute the end offset, eoff, such that [off, eoff) does not span a
4507 * page boundary and eoff is not greater than the end of the buffer.
4508 * The end of the buffer, in this case, is our file EOF, not the
4509 * allocation size of the buffer.
4511 eoff = (off + PAGE_SIZE) & ~(vm_ooffset_t)PAGE_MASK;
4512 if (eoff > bp->b_offset + bp->b_bcount)
4513 eoff = bp->b_offset + bp->b_bcount;
4516 * Set valid range. This is typically the entire buffer and thus the
4520 vm_page_set_valid_range(m, off & PAGE_MASK, eoff - off);
4524 * vfs_page_set_validclean:
4526 * Set the valid bits and clear the dirty bits in a page based on the
4527 * supplied offset. The range is restricted to the buffer's size.
4530 vfs_page_set_validclean(struct buf *bp, vm_ooffset_t off, vm_page_t m)
4532 vm_ooffset_t soff, eoff;
4535 * Start and end offsets in buffer. eoff - soff may not cross a
4536 * page boundary or cross the end of the buffer. The end of the
4537 * buffer, in this case, is our file EOF, not the allocation size
4541 eoff = (off + PAGE_SIZE) & ~(off_t)PAGE_MASK;
4542 if (eoff > bp->b_offset + bp->b_bcount)
4543 eoff = bp->b_offset + bp->b_bcount;
4546 * Set valid range. This is typically the entire buffer and thus the
4550 vm_page_set_validclean(
4552 (vm_offset_t) (soff & PAGE_MASK),
4553 (vm_offset_t) (eoff - soff)
4559 * Ensure that all buffer pages are not exclusive busied. If any page is
4560 * exclusive busy, drain it.
4563 vfs_drain_busy_pages(struct buf *bp)
4568 VM_OBJECT_ASSERT_WLOCKED(bp->b_bufobj->bo_object);
4570 for (i = 0; i < bp->b_npages; i++) {
4572 if (vm_page_xbusied(m)) {
4573 for (; last_busied < i; last_busied++)
4574 vm_page_sbusy(bp->b_pages[last_busied]);
4575 while (vm_page_xbusied(m)) {
4577 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object);
4578 vm_page_busy_sleep(m, "vbpage", true);
4579 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object);
4583 for (i = 0; i < last_busied; i++)
4584 vm_page_sunbusy(bp->b_pages[i]);
4588 * This routine is called before a device strategy routine.
4589 * It is used to tell the VM system that paging I/O is in
4590 * progress, and treat the pages associated with the buffer
4591 * almost as being exclusive busy. Also the object paging_in_progress
4592 * flag is handled to make sure that the object doesn't become
4595 * Since I/O has not been initiated yet, certain buffer flags
4596 * such as BIO_ERROR or B_INVAL may be in an inconsistent state
4597 * and should be ignored.
4600 vfs_busy_pages(struct buf *bp, int clear_modify)
4608 if (!(bp->b_flags & B_VMIO))
4611 obj = bp->b_bufobj->bo_object;
4612 foff = bp->b_offset;
4613 KASSERT(bp->b_offset != NOOFFSET,
4614 ("vfs_busy_pages: no buffer offset"));
4615 VM_OBJECT_WLOCK(obj);
4616 vfs_drain_busy_pages(bp);
4617 if (bp->b_bufsize != 0)
4618 vfs_setdirty_locked_object(bp);
4620 for (i = 0; i < bp->b_npages; i++) {
4623 if ((bp->b_flags & B_CLUSTER) == 0) {
4624 vm_object_pip_add(obj, 1);
4628 * When readying a buffer for a read ( i.e
4629 * clear_modify == 0 ), it is important to do
4630 * bogus_page replacement for valid pages in
4631 * partially instantiated buffers. Partially
4632 * instantiated buffers can, in turn, occur when
4633 * reconstituting a buffer from its VM backing store
4634 * base. We only have to do this if B_CACHE is
4635 * clear ( which causes the I/O to occur in the
4636 * first place ). The replacement prevents the read
4637 * I/O from overwriting potentially dirty VM-backed
4638 * pages. XXX bogus page replacement is, uh, bogus.
4639 * It may not work properly with small-block devices.
4640 * We need to find a better way.
4643 pmap_remove_write(m);
4644 vfs_page_set_validclean(bp, foff, m);
4645 } else if (m->valid == VM_PAGE_BITS_ALL &&
4646 (bp->b_flags & B_CACHE) == 0) {
4647 bp->b_pages[i] = bogus_page;
4650 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK;
4652 VM_OBJECT_WUNLOCK(obj);
4653 if (bogus && buf_mapped(bp)) {
4654 BUF_CHECK_MAPPED(bp);
4655 pmap_qenter(trunc_page((vm_offset_t)bp->b_data),
4656 bp->b_pages, bp->b_npages);
4661 * vfs_bio_set_valid:
4663 * Set the range within the buffer to valid. The range is
4664 * relative to the beginning of the buffer, b_offset. Note that
4665 * b_offset itself may be offset from the beginning of the first
4669 vfs_bio_set_valid(struct buf *bp, int base, int size)
4674 if (!(bp->b_flags & B_VMIO))
4678 * Fixup base to be relative to beginning of first page.
4679 * Set initial n to be the maximum number of bytes in the
4680 * first page that can be validated.
4682 base += (bp->b_offset & PAGE_MASK);
4683 n = PAGE_SIZE - (base & PAGE_MASK);
4685 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object);
4686 for (i = base / PAGE_SIZE; size > 0 && i < bp->b_npages; ++i) {
4690 vm_page_set_valid_range(m, base & PAGE_MASK, n);
4695 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object);
4701 * If the specified buffer is a non-VMIO buffer, clear the entire
4702 * buffer. If the specified buffer is a VMIO buffer, clear and
4703 * validate only the previously invalid portions of the buffer.
4704 * This routine essentially fakes an I/O, so we need to clear
4705 * BIO_ERROR and B_INVAL.
4707 * Note that while we only theoretically need to clear through b_bcount,
4708 * we go ahead and clear through b_bufsize.
4711 vfs_bio_clrbuf(struct buf *bp)
4713 int i, j, mask, sa, ea, slide;
4715 if ((bp->b_flags & (B_VMIO | B_MALLOC)) != B_VMIO) {
4719 bp->b_flags &= ~B_INVAL;
4720 bp->b_ioflags &= ~BIO_ERROR;
4721 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object);
4722 if ((bp->b_npages == 1) && (bp->b_bufsize < PAGE_SIZE) &&
4723 (bp->b_offset & PAGE_MASK) == 0) {
4724 if (bp->b_pages[0] == bogus_page)
4726 mask = (1 << (bp->b_bufsize / DEV_BSIZE)) - 1;
4727 VM_OBJECT_ASSERT_WLOCKED(bp->b_pages[0]->object);
4728 if ((bp->b_pages[0]->valid & mask) == mask)
4730 if ((bp->b_pages[0]->valid & mask) == 0) {
4731 pmap_zero_page_area(bp->b_pages[0], 0, bp->b_bufsize);
4732 bp->b_pages[0]->valid |= mask;
4736 sa = bp->b_offset & PAGE_MASK;
4738 for (i = 0; i < bp->b_npages; i++, sa = 0) {
4739 slide = imin(slide + PAGE_SIZE, bp->b_offset + bp->b_bufsize);
4740 ea = slide & PAGE_MASK;
4743 if (bp->b_pages[i] == bogus_page)
4746 mask = ((1 << ((ea - sa) / DEV_BSIZE)) - 1) << j;
4747 VM_OBJECT_ASSERT_WLOCKED(bp->b_pages[i]->object);
4748 if ((bp->b_pages[i]->valid & mask) == mask)
4750 if ((bp->b_pages[i]->valid & mask) == 0)
4751 pmap_zero_page_area(bp->b_pages[i], sa, ea - sa);
4753 for (; sa < ea; sa += DEV_BSIZE, j++) {
4754 if ((bp->b_pages[i]->valid & (1 << j)) == 0) {
4755 pmap_zero_page_area(bp->b_pages[i],
4760 bp->b_pages[i]->valid |= mask;
4763 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object);
4768 vfs_bio_bzero_buf(struct buf *bp, int base, int size)
4773 if (buf_mapped(bp)) {
4774 BUF_CHECK_MAPPED(bp);
4775 bzero(bp->b_data + base, size);
4777 BUF_CHECK_UNMAPPED(bp);
4778 n = PAGE_SIZE - (base & PAGE_MASK);
4779 for (i = base / PAGE_SIZE; size > 0 && i < bp->b_npages; ++i) {
4783 pmap_zero_page_area(m, base & PAGE_MASK, n);
4792 * Update buffer flags based on I/O request parameters, optionally releasing the
4793 * buffer. If it's VMIO or direct I/O, the buffer pages are released to the VM,
4794 * where they may be placed on a page queue (VMIO) or freed immediately (direct
4795 * I/O). Otherwise the buffer is released to the cache.
4798 b_io_dismiss(struct buf *bp, int ioflag, bool release)
4801 KASSERT((ioflag & IO_NOREUSE) == 0 || (ioflag & IO_VMIO) != 0,
4802 ("buf %p non-VMIO noreuse", bp));
4804 if ((ioflag & IO_DIRECT) != 0)
4805 bp->b_flags |= B_DIRECT;
4806 if ((ioflag & (IO_VMIO | IO_DIRECT)) != 0 && LIST_EMPTY(&bp->b_dep)) {
4807 bp->b_flags |= B_RELBUF;
4808 if ((ioflag & IO_NOREUSE) != 0)
4809 bp->b_flags |= B_NOREUSE;
4817 vfs_bio_brelse(struct buf *bp, int ioflag)
4820 b_io_dismiss(bp, ioflag, true);
4824 vfs_bio_set_flags(struct buf *bp, int ioflag)
4827 b_io_dismiss(bp, ioflag, false);
4831 * vm_hold_load_pages and vm_hold_free_pages get pages into
4832 * a buffers address space. The pages are anonymous and are
4833 * not associated with a file object.
4836 vm_hold_load_pages(struct buf *bp, vm_offset_t from, vm_offset_t to)
4842 BUF_CHECK_MAPPED(bp);
4844 to = round_page(to);
4845 from = round_page(from);
4846 index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT;
4848 for (pg = from; pg < to; pg += PAGE_SIZE, index++) {
4850 * note: must allocate system pages since blocking here
4851 * could interfere with paging I/O, no matter which
4854 p = vm_page_alloc(NULL, 0, VM_ALLOC_SYSTEM | VM_ALLOC_NOOBJ |
4855 VM_ALLOC_WIRED | VM_ALLOC_COUNT((to - pg) >> PAGE_SHIFT) |
4857 pmap_qenter(pg, &p, 1);
4858 bp->b_pages[index] = p;
4860 bp->b_npages = index;
4863 /* Return pages associated with this buf to the vm system */
4865 vm_hold_free_pages(struct buf *bp, int newbsize)
4869 int index, newnpages;
4871 BUF_CHECK_MAPPED(bp);
4873 from = round_page((vm_offset_t)bp->b_data + newbsize);
4874 newnpages = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT;
4875 if (bp->b_npages > newnpages)
4876 pmap_qremove(from, bp->b_npages - newnpages);
4877 for (index = newnpages; index < bp->b_npages; index++) {
4878 p = bp->b_pages[index];
4879 bp->b_pages[index] = NULL;
4883 vm_wire_sub(bp->b_npages - newnpages);
4884 bp->b_npages = newnpages;
4888 * Map an IO request into kernel virtual address space.
4890 * All requests are (re)mapped into kernel VA space.
4891 * Notice that we use b_bufsize for the size of the buffer
4892 * to be mapped. b_bcount might be modified by the driver.
4894 * Note that even if the caller determines that the address space should
4895 * be valid, a race or a smaller-file mapped into a larger space may
4896 * actually cause vmapbuf() to fail, so all callers of vmapbuf() MUST
4897 * check the return value.
4899 * This function only works with pager buffers.
4902 vmapbuf(struct buf *bp, int mapbuf)
4907 if (bp->b_bufsize < 0)
4909 prot = VM_PROT_READ;
4910 if (bp->b_iocmd == BIO_READ)
4911 prot |= VM_PROT_WRITE; /* Less backwards than it looks */
4912 if ((pidx = vm_fault_quick_hold_pages(&curproc->p_vmspace->vm_map,
4913 (vm_offset_t)bp->b_data, bp->b_bufsize, prot, bp->b_pages,
4914 btoc(MAXPHYS))) < 0)
4916 bp->b_npages = pidx;
4917 bp->b_offset = ((vm_offset_t)bp->b_data) & PAGE_MASK;
4918 if (mapbuf || !unmapped_buf_allowed) {
4919 pmap_qenter((vm_offset_t)bp->b_kvabase, bp->b_pages, pidx);
4920 bp->b_data = bp->b_kvabase + bp->b_offset;
4922 bp->b_data = unmapped_buf;
4927 * Free the io map PTEs associated with this IO operation.
4928 * We also invalidate the TLB entries and restore the original b_addr.
4930 * This function only works with pager buffers.
4933 vunmapbuf(struct buf *bp)
4937 npages = bp->b_npages;
4939 pmap_qremove(trunc_page((vm_offset_t)bp->b_data), npages);
4940 vm_page_unhold_pages(bp->b_pages, npages);
4942 bp->b_data = unmapped_buf;
4946 bdone(struct buf *bp)
4950 mtxp = mtx_pool_find(mtxpool_sleep, bp);
4952 bp->b_flags |= B_DONE;
4958 bwait(struct buf *bp, u_char pri, const char *wchan)
4962 mtxp = mtx_pool_find(mtxpool_sleep, bp);
4964 while ((bp->b_flags & B_DONE) == 0)
4965 msleep(bp, mtxp, pri, wchan, 0);
4970 bufsync(struct bufobj *bo, int waitfor)
4973 return (VOP_FSYNC(bo2vnode(bo), waitfor, curthread));
4977 bufstrategy(struct bufobj *bo, struct buf *bp)
4983 KASSERT(vp == bo->bo_private, ("Inconsistent vnode bufstrategy"));
4984 KASSERT(vp->v_type != VCHR && vp->v_type != VBLK,
4985 ("Wrong vnode in bufstrategy(bp=%p, vp=%p)", bp, vp));
4986 i = VOP_STRATEGY(vp, bp);
4987 KASSERT(i == 0, ("VOP_STRATEGY failed bp=%p vp=%p", bp, bp->b_vp));
4991 * Initialize a struct bufobj before use. Memory is assumed zero filled.
4994 bufobj_init(struct bufobj *bo, void *private)
4996 static volatile int bufobj_cleanq;
4999 atomic_fetchadd_int(&bufobj_cleanq, 1) % buf_domains;
5000 rw_init(BO_LOCKPTR(bo), "bufobj interlock");
5001 bo->bo_private = private;
5002 TAILQ_INIT(&bo->bo_clean.bv_hd);
5003 TAILQ_INIT(&bo->bo_dirty.bv_hd);
5007 bufobj_wrefl(struct bufobj *bo)
5010 KASSERT(bo != NULL, ("NULL bo in bufobj_wref"));
5011 ASSERT_BO_WLOCKED(bo);
5016 bufobj_wref(struct bufobj *bo)
5019 KASSERT(bo != NULL, ("NULL bo in bufobj_wref"));
5026 bufobj_wdrop(struct bufobj *bo)
5029 KASSERT(bo != NULL, ("NULL bo in bufobj_wdrop"));
5031 KASSERT(bo->bo_numoutput > 0, ("bufobj_wdrop non-positive count"));
5032 if ((--bo->bo_numoutput == 0) && (bo->bo_flag & BO_WWAIT)) {
5033 bo->bo_flag &= ~BO_WWAIT;
5034 wakeup(&bo->bo_numoutput);
5040 bufobj_wwait(struct bufobj *bo, int slpflag, int timeo)
5044 KASSERT(bo != NULL, ("NULL bo in bufobj_wwait"));
5045 ASSERT_BO_WLOCKED(bo);
5047 while (bo->bo_numoutput) {
5048 bo->bo_flag |= BO_WWAIT;
5049 error = msleep(&bo->bo_numoutput, BO_LOCKPTR(bo),
5050 slpflag | (PRIBIO + 1), "bo_wwait", timeo);
5058 * Set bio_data or bio_ma for struct bio from the struct buf.
5061 bdata2bio(struct buf *bp, struct bio *bip)
5064 if (!buf_mapped(bp)) {
5065 KASSERT(unmapped_buf_allowed, ("unmapped"));
5066 bip->bio_ma = bp->b_pages;
5067 bip->bio_ma_n = bp->b_npages;
5068 bip->bio_data = unmapped_buf;
5069 bip->bio_ma_offset = (vm_offset_t)bp->b_offset & PAGE_MASK;
5070 bip->bio_flags |= BIO_UNMAPPED;
5071 KASSERT(round_page(bip->bio_ma_offset + bip->bio_length) /
5072 PAGE_SIZE == bp->b_npages,
5073 ("Buffer %p too short: %d %lld %d", bp, bip->bio_ma_offset,
5074 (long long)bip->bio_length, bip->bio_ma_n));
5076 bip->bio_data = bp->b_data;
5082 * The MIPS pmap code currently doesn't handle aliased pages.
5083 * The VIPT caches may not handle page aliasing themselves, leading
5084 * to data corruption.
5086 * As such, this code makes a system extremely unhappy if said
5087 * system doesn't support unaliasing the above situation in hardware.
5088 * Some "recent" systems (eg some mips24k/mips74k cores) don't enable
5089 * this feature at build time, so it has to be handled in software.
5091 * Once the MIPS pmap/cache code grows to support this function on
5092 * earlier chips, it should be flipped back off.
5095 static int buf_pager_relbuf = 1;
5097 static int buf_pager_relbuf = 0;
5099 SYSCTL_INT(_vfs, OID_AUTO, buf_pager_relbuf, CTLFLAG_RWTUN,
5100 &buf_pager_relbuf, 0,
5101 "Make buffer pager release buffers after reading");
5104 * The buffer pager. It uses buffer reads to validate pages.
5106 * In contrast to the generic local pager from vm/vnode_pager.c, this
5107 * pager correctly and easily handles volumes where the underlying
5108 * device block size is greater than the machine page size. The
5109 * buffer cache transparently extends the requested page run to be
5110 * aligned at the block boundary, and does the necessary bogus page
5111 * replacements in the addends to avoid obliterating already valid
5114 * The only non-trivial issue is that the exclusive busy state for
5115 * pages, which is assumed by the vm_pager_getpages() interface, is
5116 * incompatible with the VMIO buffer cache's desire to share-busy the
5117 * pages. This function performs a trivial downgrade of the pages'
5118 * state before reading buffers, and a less trivial upgrade from the
5119 * shared-busy to excl-busy state after the read.
5122 vfs_bio_getpages(struct vnode *vp, vm_page_t *ma, int count,
5123 int *rbehind, int *rahead, vbg_get_lblkno_t get_lblkno,
5124 vbg_get_blksize_t get_blksize)
5131 vm_ooffset_t la, lb, poff, poffe;
5133 int bo_bs, br_flags, error, i, pgsin, pgsin_a, pgsin_b;
5136 object = vp->v_object;
5139 la = IDX_TO_OFF(ma[count - 1]->pindex);
5140 if (la >= object->un_pager.vnp.vnp_size)
5141 return (VM_PAGER_BAD);
5144 * Change the meaning of la from where the last requested page starts
5145 * to where it ends, because that's the end of the requested region
5146 * and the start of the potential read-ahead region.
5149 lpart = la > object->un_pager.vnp.vnp_size;
5150 bo_bs = get_blksize(vp, get_lblkno(vp, IDX_TO_OFF(ma[0]->pindex)));
5153 * Calculate read-ahead, behind and total pages.
5156 lb = IDX_TO_OFF(ma[0]->pindex);
5157 pgsin_b = OFF_TO_IDX(lb - rounddown2(lb, bo_bs));
5159 if (rbehind != NULL)
5161 pgsin_a = OFF_TO_IDX(roundup2(la, bo_bs) - la);
5162 if (la + IDX_TO_OFF(pgsin_a) >= object->un_pager.vnp.vnp_size)
5163 pgsin_a = OFF_TO_IDX(roundup2(object->un_pager.vnp.vnp_size,
5168 VM_CNT_INC(v_vnodein);
5169 VM_CNT_ADD(v_vnodepgsin, pgsin);
5171 br_flags = (mp != NULL && (mp->mnt_kern_flag & MNTK_UNMAPPED_BUFS)
5172 != 0) ? GB_UNMAPPED : 0;
5173 VM_OBJECT_WLOCK(object);
5175 for (i = 0; i < count; i++)
5176 vm_page_busy_downgrade(ma[i]);
5177 VM_OBJECT_WUNLOCK(object);
5180 for (i = 0; i < count; i++) {
5184 * Pages are shared busy and the object lock is not
5185 * owned, which together allow for the pages'
5186 * invalidation. The racy test for validity avoids
5187 * useless creation of the buffer for the most typical
5188 * case when invalidation is not used in redo or for
5189 * parallel read. The shared->excl upgrade loop at
5190 * the end of the function catches the race in a
5191 * reliable way (protected by the object lock).
5193 if (m->valid == VM_PAGE_BITS_ALL)
5196 poff = IDX_TO_OFF(m->pindex);
5197 poffe = MIN(poff + PAGE_SIZE, object->un_pager.vnp.vnp_size);
5198 for (; poff < poffe; poff += bsize) {
5199 lbn = get_lblkno(vp, poff);
5204 bsize = get_blksize(vp, lbn);
5205 error = bread_gb(vp, lbn, bsize, curthread->td_ucred,
5209 if (LIST_EMPTY(&bp->b_dep)) {
5211 * Invalidation clears m->valid, but
5212 * may leave B_CACHE flag if the
5213 * buffer existed at the invalidation
5214 * time. In this case, recycle the
5215 * buffer to do real read on next
5216 * bread() after redo.
5218 * Otherwise B_RELBUF is not strictly
5219 * necessary, enable to reduce buf
5222 if (buf_pager_relbuf ||
5223 m->valid != VM_PAGE_BITS_ALL)
5224 bp->b_flags |= B_RELBUF;
5226 bp->b_flags &= ~B_NOCACHE;
5232 KASSERT(1 /* racy, enable for debugging */ ||
5233 m->valid == VM_PAGE_BITS_ALL || i == count - 1,
5234 ("buf %d %p invalid", i, m));
5235 if (i == count - 1 && lpart) {
5236 VM_OBJECT_WLOCK(object);
5237 if (m->valid != 0 &&
5238 m->valid != VM_PAGE_BITS_ALL)
5239 vm_page_zero_invalid(m, TRUE);
5240 VM_OBJECT_WUNLOCK(object);
5246 VM_OBJECT_WLOCK(object);
5248 for (i = 0; i < count; i++) {
5249 vm_page_sunbusy(ma[i]);
5250 ma[i] = vm_page_grab(object, ma[i]->pindex, VM_ALLOC_NORMAL);
5253 * Since the pages were only sbusy while neither the
5254 * buffer nor the object lock was held by us, or
5255 * reallocated while vm_page_grab() slept for busy
5256 * relinguish, they could have been invalidated.
5257 * Recheck the valid bits and re-read as needed.
5259 * Note that the last page is made fully valid in the
5260 * read loop, and partial validity for the page at
5261 * index count - 1 could mean that the page was
5262 * invalidated or removed, so we must restart for
5265 if (ma[i]->valid != VM_PAGE_BITS_ALL)
5268 if (redo && error == 0)
5270 VM_OBJECT_WUNLOCK(object);
5271 return (error != 0 ? VM_PAGER_ERROR : VM_PAGER_OK);
5274 #include "opt_ddb.h"
5276 #include <ddb/ddb.h>
5278 /* DDB command to show buffer data */
5279 DB_SHOW_COMMAND(buffer, db_show_buffer)
5282 struct buf *bp = (struct buf *)addr;
5283 #ifdef FULL_BUF_TRACKING
5288 db_printf("usage: show buffer <addr>\n");
5292 db_printf("buf at %p\n", bp);
5293 db_printf("b_flags = 0x%b, b_xflags=0x%b, b_vflags=0x%b\n",
5294 (u_int)bp->b_flags, PRINT_BUF_FLAGS, (u_int)bp->b_xflags,
5295 PRINT_BUF_XFLAGS, (u_int)bp->b_vflags, PRINT_BUF_VFLAGS);
5297 "b_error = %d, b_bufsize = %ld, b_bcount = %ld, b_resid = %ld\n"
5298 "b_bufobj = (%p), b_data = %p, b_blkno = %jd, b_lblkno = %jd, "
5300 bp->b_error, bp->b_bufsize, bp->b_bcount, bp->b_resid,
5301 bp->b_bufobj, bp->b_data, (intmax_t)bp->b_blkno,
5302 (intmax_t)bp->b_lblkno, bp->b_dep.lh_first);
5303 db_printf("b_kvabase = %p, b_kvasize = %d\n",
5304 bp->b_kvabase, bp->b_kvasize);
5307 db_printf("b_npages = %d, pages(OBJ, IDX, PA): ", bp->b_npages);
5308 for (i = 0; i < bp->b_npages; i++) {
5312 db_printf("(%p, 0x%lx, 0x%lx)", m->object,
5314 (u_long)VM_PAGE_TO_PHYS(m));
5316 db_printf("( ??? )");
5317 if ((i + 1) < bp->b_npages)
5322 BUF_LOCKPRINTINFO(bp);
5323 #if defined(FULL_BUF_TRACKING)
5324 db_printf("b_io_tracking: b_io_tcnt = %u\n", bp->b_io_tcnt);
5326 i = bp->b_io_tcnt % BUF_TRACKING_SIZE;
5327 for (j = 1; j <= BUF_TRACKING_SIZE; j++) {
5328 if (bp->b_io_tracking[BUF_TRACKING_ENTRY(i - j)] == NULL)
5330 db_printf(" %2u: %s\n", j,
5331 bp->b_io_tracking[BUF_TRACKING_ENTRY(i - j)]);
5333 #elif defined(BUF_TRACKING)
5334 db_printf("b_io_tracking: %s\n", bp->b_io_tracking);
5339 DB_SHOW_COMMAND(bufqueues, bufqueues)
5341 struct bufdomain *bd;
5346 db_printf("bqempty: %d\n", bqempty.bq_len);
5348 for (i = 0; i < buf_domains; i++) {
5350 db_printf("Buf domain %d\n", i);
5351 db_printf("\tfreebufs\t%d\n", bd->bd_freebuffers);
5352 db_printf("\tlofreebufs\t%d\n", bd->bd_lofreebuffers);
5353 db_printf("\thifreebufs\t%d\n", bd->bd_hifreebuffers);
5355 db_printf("\tbufspace\t%ld\n", bd->bd_bufspace);
5356 db_printf("\tmaxbufspace\t%ld\n", bd->bd_maxbufspace);
5357 db_printf("\thibufspace\t%ld\n", bd->bd_hibufspace);
5358 db_printf("\tlobufspace\t%ld\n", bd->bd_lobufspace);
5359 db_printf("\tbufspacethresh\t%ld\n", bd->bd_bufspacethresh);
5361 db_printf("\tnumdirtybuffers\t%d\n", bd->bd_numdirtybuffers);
5362 db_printf("\tlodirtybuffers\t%d\n", bd->bd_lodirtybuffers);
5363 db_printf("\thidirtybuffers\t%d\n", bd->bd_hidirtybuffers);
5364 db_printf("\tdirtybufthresh\t%d\n", bd->bd_dirtybufthresh);
5367 TAILQ_FOREACH(bp, &bd->bd_cleanq->bq_queue, b_freelist)
5368 total += bp->b_bufsize;
5369 db_printf("\tcleanq count\t%d (%ld)\n",
5370 bd->bd_cleanq->bq_len, total);
5372 TAILQ_FOREACH(bp, &bd->bd_dirtyq.bq_queue, b_freelist)
5373 total += bp->b_bufsize;
5374 db_printf("\tdirtyq count\t%d (%ld)\n",
5375 bd->bd_dirtyq.bq_len, total);
5376 db_printf("\twakeup\t\t%d\n", bd->bd_wanted);
5377 db_printf("\tlim\t\t%d\n", bd->bd_lim);
5378 db_printf("\tCPU ");
5379 for (j = 0; j <= mp_maxid; j++)
5380 db_printf("%d, ", bd->bd_subq[j].bq_len);
5384 for (j = 0; j < nbuf; j++)
5385 if (buf[j].b_domain == i && BUF_ISLOCKED(&buf[j])) {
5387 total += buf[j].b_bufsize;
5389 db_printf("\tLocked buffers: %d space %ld\n", cnt, total);
5392 for (j = 0; j < nbuf; j++)
5393 if (buf[j].b_domain == i) {
5395 total += buf[j].b_bufsize;
5397 db_printf("\tTotal buffers: %d space %ld\n", cnt, total);
5401 DB_SHOW_COMMAND(lockedbufs, lockedbufs)
5406 for (i = 0; i < nbuf; i++) {
5408 if (BUF_ISLOCKED(bp)) {
5409 db_show_buffer((uintptr_t)bp, 1, 0, NULL);
5417 DB_SHOW_COMMAND(vnodebufs, db_show_vnodebufs)
5423 db_printf("usage: show vnodebufs <addr>\n");
5426 vp = (struct vnode *)addr;
5427 db_printf("Clean buffers:\n");
5428 TAILQ_FOREACH(bp, &vp->v_bufobj.bo_clean.bv_hd, b_bobufs) {
5429 db_show_buffer((uintptr_t)bp, 1, 0, NULL);
5432 db_printf("Dirty buffers:\n");
5433 TAILQ_FOREACH(bp, &vp->v_bufobj.bo_dirty.bv_hd, b_bobufs) {
5434 db_show_buffer((uintptr_t)bp, 1, 0, NULL);
5439 DB_COMMAND(countfreebufs, db_coundfreebufs)
5442 int i, used = 0, nfree = 0;
5445 db_printf("usage: countfreebufs\n");
5449 for (i = 0; i < nbuf; i++) {
5451 if (bp->b_qindex == QUEUE_EMPTY)
5457 db_printf("Counted %d free, %d used (%d tot)\n", nfree, used,
5459 db_printf("numfreebuffers is %d\n", numfreebuffers);