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_INT|CTLFLAG_MPSAFE|CTLFLAG_RW, &lodirtybuffers,
265 __offsetof(struct bufdomain, bd_lodirtybuffers), sysctl_bufdomain_int, "I",
266 "How many buffers we want to have free before bufdaemon can sleep");
267 static int hidirtybuffers;
268 SYSCTL_PROC(_vfs, OID_AUTO, hidirtybuffers,
269 CTLTYPE_INT|CTLFLAG_MPSAFE|CTLFLAG_RW, &hidirtybuffers,
270 __offsetof(struct bufdomain, bd_hidirtybuffers), sysctl_bufdomain_int, "I",
271 "When the number of dirty buffers is considered severe");
273 SYSCTL_PROC(_vfs, OID_AUTO, dirtybufthresh,
274 CTLTYPE_INT|CTLFLAG_MPSAFE|CTLFLAG_RW, &dirtybufthresh,
275 __offsetof(struct bufdomain, bd_dirtybufthresh), sysctl_bufdomain_int, "I",
276 "Number of bdwrite to bawrite conversions to clear dirty buffers");
277 static int numfreebuffers;
278 SYSCTL_INT(_vfs, OID_AUTO, numfreebuffers, CTLFLAG_RD, &numfreebuffers, 0,
279 "Number of free buffers");
280 static int lofreebuffers;
281 SYSCTL_PROC(_vfs, OID_AUTO, lofreebuffers,
282 CTLTYPE_INT|CTLFLAG_MPSAFE|CTLFLAG_RW, &lofreebuffers,
283 __offsetof(struct bufdomain, bd_lofreebuffers), sysctl_bufdomain_int, "I",
284 "Target number of free buffers");
285 static int hifreebuffers;
286 SYSCTL_PROC(_vfs, OID_AUTO, hifreebuffers,
287 CTLTYPE_INT|CTLFLAG_MPSAFE|CTLFLAG_RW, &hifreebuffers,
288 __offsetof(struct bufdomain, bd_hifreebuffers), sysctl_bufdomain_int, "I",
289 "Threshold for clean buffer recycling");
290 static counter_u64_t getnewbufcalls;
291 SYSCTL_COUNTER_U64(_vfs, OID_AUTO, getnewbufcalls, CTLFLAG_RD,
292 &getnewbufcalls, "Number of calls to getnewbuf");
293 static counter_u64_t getnewbufrestarts;
294 SYSCTL_COUNTER_U64(_vfs, OID_AUTO, getnewbufrestarts, CTLFLAG_RD,
296 "Number of times getnewbuf has had to restart a buffer acquisition");
297 static counter_u64_t mappingrestarts;
298 SYSCTL_COUNTER_U64(_vfs, OID_AUTO, mappingrestarts, CTLFLAG_RD,
300 "Number of times getblk has had to restart a buffer mapping for "
302 static counter_u64_t numbufallocfails;
303 SYSCTL_COUNTER_U64(_vfs, OID_AUTO, numbufallocfails, CTLFLAG_RW,
304 &numbufallocfails, "Number of times buffer allocations failed");
305 static int flushbufqtarget = 100;
306 SYSCTL_INT(_vfs, OID_AUTO, flushbufqtarget, CTLFLAG_RW, &flushbufqtarget, 0,
307 "Amount of work to do in flushbufqueues when helping bufdaemon");
308 static counter_u64_t notbufdflushes;
309 SYSCTL_COUNTER_U64(_vfs, OID_AUTO, notbufdflushes, CTLFLAG_RD, ¬bufdflushes,
310 "Number of dirty buffer flushes done by the bufdaemon helpers");
311 static long barrierwrites;
312 SYSCTL_LONG(_vfs, OID_AUTO, barrierwrites, CTLFLAG_RW, &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)(((uintptr_t)&bdomain[i]) + arg2) =
445 sysctl_bufdomain_long(SYSCTL_HANDLER_ARGS)
451 value = *(long *)arg1;
452 error = sysctl_handle_long(oidp, &value, 0, req);
453 if (error != 0 || req->newptr == NULL)
455 *(long *)arg1 = value;
456 for (i = 0; i < buf_domains; i++)
457 *(long *)(uintptr_t)(((uintptr_t)&bdomain[i]) + arg2) =
463 #if defined(COMPAT_FREEBSD4) || defined(COMPAT_FREEBSD5) || \
464 defined(COMPAT_FREEBSD6) || defined(COMPAT_FREEBSD7)
466 sysctl_bufspace(SYSCTL_HANDLER_ARGS)
473 for (i = 0; i < buf_domains; i++)
474 lvalue += bdomain[i].bd_bufspace;
475 if (sizeof(int) == sizeof(long) || req->oldlen >= sizeof(long))
476 return (sysctl_handle_long(oidp, &lvalue, 0, req));
477 if (lvalue > INT_MAX)
478 /* On overflow, still write out a long to trigger ENOMEM. */
479 return (sysctl_handle_long(oidp, &lvalue, 0, req));
481 return (sysctl_handle_int(oidp, &ivalue, 0, req));
485 sysctl_bufspace(SYSCTL_HANDLER_ARGS)
491 for (i = 0; i < buf_domains; i++)
492 lvalue += bdomain[i].bd_bufspace;
493 return (sysctl_handle_long(oidp, &lvalue, 0, req));
498 sysctl_numdirtybuffers(SYSCTL_HANDLER_ARGS)
504 for (i = 0; i < buf_domains; i++)
505 value += bdomain[i].bd_numdirtybuffers;
506 return (sysctl_handle_int(oidp, &value, 0, req));
512 * Wakeup any bwillwrite() waiters.
517 mtx_lock(&bdirtylock);
522 mtx_unlock(&bdirtylock);
528 * Clear a domain from the appropriate bitsets when dirtybuffers
532 bd_clear(struct bufdomain *bd)
535 mtx_lock(&bdirtylock);
536 if (bd->bd_numdirtybuffers <= bd->bd_lodirtybuffers)
537 BIT_CLR(BUF_DOMAINS, BD_DOMAIN(bd), &bdlodirty);
538 if (bd->bd_numdirtybuffers <= bd->bd_hidirtybuffers)
539 BIT_CLR(BUF_DOMAINS, BD_DOMAIN(bd), &bdhidirty);
540 mtx_unlock(&bdirtylock);
546 * Set a domain in the appropriate bitsets when dirtybuffers
550 bd_set(struct bufdomain *bd)
553 mtx_lock(&bdirtylock);
554 if (bd->bd_numdirtybuffers > bd->bd_lodirtybuffers)
555 BIT_SET(BUF_DOMAINS, BD_DOMAIN(bd), &bdlodirty);
556 if (bd->bd_numdirtybuffers > bd->bd_hidirtybuffers)
557 BIT_SET(BUF_DOMAINS, BD_DOMAIN(bd), &bdhidirty);
558 mtx_unlock(&bdirtylock);
564 * Decrement the numdirtybuffers count by one and wakeup any
565 * threads blocked in bwillwrite().
568 bdirtysub(struct buf *bp)
570 struct bufdomain *bd;
574 num = atomic_fetchadd_int(&bd->bd_numdirtybuffers, -1);
575 if (num == (bd->bd_lodirtybuffers + bd->bd_hidirtybuffers) / 2)
577 if (num == bd->bd_lodirtybuffers || num == bd->bd_hidirtybuffers)
584 * Increment the numdirtybuffers count by one and wakeup the buf
588 bdirtyadd(struct buf *bp)
590 struct bufdomain *bd;
594 * Only do the wakeup once as we cross the boundary. The
595 * buf daemon will keep running until the condition clears.
598 num = atomic_fetchadd_int(&bd->bd_numdirtybuffers, 1);
599 if (num == (bd->bd_lodirtybuffers + bd->bd_hidirtybuffers) / 2)
601 if (num == bd->bd_lodirtybuffers || num == bd->bd_hidirtybuffers)
606 * bufspace_daemon_wakeup:
608 * Wakeup the daemons responsible for freeing clean bufs.
611 bufspace_daemon_wakeup(struct bufdomain *bd)
615 * avoid the lock if the daemon is running.
617 if (atomic_fetchadd_int(&bd->bd_running, 1) == 0) {
619 atomic_store_int(&bd->bd_running, 1);
620 wakeup(&bd->bd_running);
626 * bufspace_daemon_wait:
628 * Sleep until the domain falls below a limit or one second passes.
631 bufspace_daemon_wait(struct bufdomain *bd)
634 * Re-check our limits and sleep. bd_running must be
635 * cleared prior to checking the limits to avoid missed
636 * wakeups. The waker will adjust one of bufspace or
637 * freebuffers prior to checking bd_running.
640 atomic_store_int(&bd->bd_running, 0);
641 if (bd->bd_bufspace < bd->bd_bufspacethresh &&
642 bd->bd_freebuffers > bd->bd_lofreebuffers) {
643 msleep(&bd->bd_running, BD_RUN_LOCKPTR(bd), PRIBIO|PDROP,
646 /* Avoid spurious wakeups while running. */
647 atomic_store_int(&bd->bd_running, 1);
655 * Adjust the reported bufspace for a KVA managed buffer, possibly
656 * waking any waiters.
659 bufspace_adjust(struct buf *bp, int bufsize)
661 struct bufdomain *bd;
665 KASSERT((bp->b_flags & B_MALLOC) == 0,
666 ("bufspace_adjust: malloc buf %p", bp));
668 diff = bufsize - bp->b_bufsize;
670 atomic_subtract_long(&bd->bd_bufspace, -diff);
671 } else if (diff > 0) {
672 space = atomic_fetchadd_long(&bd->bd_bufspace, diff);
673 /* Wake up the daemon on the transition. */
674 if (space < bd->bd_bufspacethresh &&
675 space + diff >= bd->bd_bufspacethresh)
676 bufspace_daemon_wakeup(bd);
678 bp->b_bufsize = bufsize;
684 * Reserve bufspace before calling allocbuf(). metadata has a
685 * different space limit than data.
688 bufspace_reserve(struct bufdomain *bd, int size, bool metadata)
694 limit = bd->bd_maxbufspace;
696 limit = bd->bd_hibufspace;
697 space = atomic_fetchadd_long(&bd->bd_bufspace, size);
700 atomic_subtract_long(&bd->bd_bufspace, size);
704 /* Wake up the daemon on the transition. */
705 if (space < bd->bd_bufspacethresh && new >= bd->bd_bufspacethresh)
706 bufspace_daemon_wakeup(bd);
714 * Release reserved bufspace after bufspace_adjust() has consumed it.
717 bufspace_release(struct bufdomain *bd, int size)
720 atomic_subtract_long(&bd->bd_bufspace, size);
726 * Wait for bufspace, acting as the buf daemon if a locked vnode is
727 * supplied. bd_wanted must be set prior to polling for space. The
728 * operation must be re-tried on return.
731 bufspace_wait(struct bufdomain *bd, struct vnode *vp, int gbflags,
732 int slpflag, int slptimeo)
735 int error, fl, norunbuf;
737 if ((gbflags & GB_NOWAIT_BD) != 0)
742 while (bd->bd_wanted) {
743 if (vp != NULL && vp->v_type != VCHR &&
744 (td->td_pflags & TDP_BUFNEED) == 0) {
747 * getblk() is called with a vnode locked, and
748 * some majority of the dirty buffers may as
749 * well belong to the vnode. Flushing the
750 * buffers there would make a progress that
751 * cannot be achieved by the buf_daemon, that
752 * cannot lock the vnode.
754 norunbuf = ~(TDP_BUFNEED | TDP_NORUNNINGBUF) |
755 (td->td_pflags & TDP_NORUNNINGBUF);
758 * Play bufdaemon. The getnewbuf() function
759 * may be called while the thread owns lock
760 * for another dirty buffer for the same
761 * vnode, which makes it impossible to use
762 * VOP_FSYNC() there, due to the buffer lock
765 td->td_pflags |= TDP_BUFNEED | TDP_NORUNNINGBUF;
766 fl = buf_flush(vp, bd, flushbufqtarget);
767 td->td_pflags &= norunbuf;
771 if (bd->bd_wanted == 0)
774 error = msleep(&bd->bd_wanted, BD_LOCKPTR(bd),
775 (PRIBIO + 4) | slpflag, "newbuf", slptimeo);
786 * buffer space management daemon. Tries to maintain some marginal
787 * amount of free buffer space so that requesting processes neither
788 * block nor work to reclaim buffers.
791 bufspace_daemon(void *arg)
793 struct bufdomain *bd;
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.
824 while (bd->bd_bufspace > bd->bd_lobufspace ||
825 bd->bd_freebuffers < bd->bd_hifreebuffers) {
826 if (buf_recycle(bd, false) != 0) {
830 * Speedup dirty if we've run out of clean
831 * buffers. This is possible in particular
832 * because softdep may held many bufs locked
833 * pending writes to other bufs which are
834 * marked for delayed write, exhausting
835 * clean space until they are written.
840 msleep(&bd->bd_wanted, BD_LOCKPTR(bd),
841 PRIBIO|PDROP, "bufspace", hz/10);
847 bufspace_daemon_wait(bd);
854 * Adjust the reported bufspace for a malloc managed buffer, possibly
855 * waking any waiters.
858 bufmallocadjust(struct buf *bp, int bufsize)
862 KASSERT((bp->b_flags & B_MALLOC) != 0,
863 ("bufmallocadjust: non-malloc buf %p", bp));
864 diff = bufsize - bp->b_bufsize;
866 atomic_subtract_long(&bufmallocspace, -diff);
868 atomic_add_long(&bufmallocspace, diff);
869 bp->b_bufsize = bufsize;
875 * Wake up processes that are waiting on asynchronous writes to fall
876 * below lorunningspace.
882 mtx_lock(&rbreqlock);
885 wakeup(&runningbufreq);
887 mtx_unlock(&rbreqlock);
893 * Decrement the outstanding write count according.
896 runningbufwakeup(struct buf *bp)
900 bspace = bp->b_runningbufspace;
903 space = atomic_fetchadd_long(&runningbufspace, -bspace);
904 KASSERT(space >= bspace, ("runningbufspace underflow %ld %ld",
906 bp->b_runningbufspace = 0;
908 * Only acquire the lock and wakeup on the transition from exceeding
909 * the threshold to falling below it.
911 if (space < lorunningspace)
913 if (space - bspace > lorunningspace)
919 * waitrunningbufspace()
921 * runningbufspace is a measure of the amount of I/O currently
922 * running. This routine is used in async-write situations to
923 * prevent creating huge backups of pending writes to a device.
924 * Only asynchronous writes are governed by this function.
926 * This does NOT turn an async write into a sync write. It waits
927 * for earlier writes to complete and generally returns before the
928 * caller's write has reached the device.
931 waitrunningbufspace(void)
934 mtx_lock(&rbreqlock);
935 while (runningbufspace > hirunningspace) {
937 msleep(&runningbufreq, &rbreqlock, PVM, "wdrain", 0);
939 mtx_unlock(&rbreqlock);
944 * vfs_buf_test_cache:
946 * Called when a buffer is extended. This function clears the B_CACHE
947 * bit if the newly extended portion of the buffer does not contain
951 vfs_buf_test_cache(struct buf *bp, vm_ooffset_t foff, vm_offset_t off,
952 vm_offset_t size, vm_page_t m)
955 VM_OBJECT_ASSERT_LOCKED(m->object);
956 if (bp->b_flags & B_CACHE) {
957 int base = (foff + off) & PAGE_MASK;
958 if (vm_page_is_valid(m, base, size) == 0)
959 bp->b_flags &= ~B_CACHE;
963 /* Wake up the buffer daemon if necessary */
969 if (bd_request == 0) {
977 * Adjust the maxbcachbuf tunable.
980 maxbcachebuf_adjust(void)
985 * maxbcachebuf must be a power of 2 >= MAXBSIZE.
988 while (i * 2 <= maxbcachebuf)
991 if (maxbcachebuf < MAXBSIZE)
992 maxbcachebuf = MAXBSIZE;
993 if (maxbcachebuf > MAXPHYS)
994 maxbcachebuf = MAXPHYS;
995 if (bootverbose != 0 && maxbcachebuf != MAXBCACHEBUF)
996 printf("maxbcachebuf=%d\n", maxbcachebuf);
1000 * bd_speedup - speedup the buffer cache flushing code
1009 if (bd_speedupreq == 0 || bd_request == 0)
1014 wakeup(&bd_request);
1015 mtx_unlock(&bdlock);
1019 #define NSWBUF_MIN 16
1023 #define TRANSIENT_DENOM 5
1025 #define TRANSIENT_DENOM 10
1029 * Calculating buffer cache scaling values and reserve space for buffer
1030 * headers. This is called during low level kernel initialization and
1031 * may be called more then once. We CANNOT write to the memory area
1032 * being reserved at this time.
1035 kern_vfs_bio_buffer_alloc(caddr_t v, long physmem_est)
1038 long maxbuf, maxbuf_sz, buf_sz, biotmap_sz;
1041 * physmem_est is in pages. Convert it to kilobytes (assumes
1042 * PAGE_SIZE is >= 1K)
1044 physmem_est = physmem_est * (PAGE_SIZE / 1024);
1046 maxbcachebuf_adjust();
1048 * The nominal buffer size (and minimum KVA allocation) is BKVASIZE.
1049 * For the first 64MB of ram nominally allocate sufficient buffers to
1050 * cover 1/4 of our ram. Beyond the first 64MB allocate additional
1051 * buffers to cover 1/10 of our ram over 64MB. When auto-sizing
1052 * the buffer cache we limit the eventual kva reservation to
1055 * factor represents the 1/4 x ram conversion.
1058 int factor = 4 * BKVASIZE / 1024;
1061 if (physmem_est > 4096)
1062 nbuf += min((physmem_est - 4096) / factor,
1064 if (physmem_est > 65536)
1065 nbuf += min((physmem_est - 65536) * 2 / (factor * 5),
1066 32 * 1024 * 1024 / (factor * 5));
1068 if (maxbcache && nbuf > maxbcache / BKVASIZE)
1069 nbuf = maxbcache / BKVASIZE;
1074 /* XXX Avoid unsigned long overflows later on with maxbufspace. */
1075 maxbuf = (LONG_MAX / 3) / BKVASIZE;
1076 if (nbuf > maxbuf) {
1078 printf("Warning: nbufs lowered from %d to %ld\n", nbuf,
1084 * Ideal allocation size for the transient bio submap is 10%
1085 * of the maximal space buffer map. This roughly corresponds
1086 * to the amount of the buffer mapped for typical UFS load.
1088 * Clip the buffer map to reserve space for the transient
1089 * BIOs, if its extent is bigger than 90% (80% on i386) of the
1090 * maximum buffer map extent on the platform.
1092 * The fall-back to the maxbuf in case of maxbcache unset,
1093 * allows to not trim the buffer KVA for the architectures
1094 * with ample KVA space.
1096 if (bio_transient_maxcnt == 0 && unmapped_buf_allowed) {
1097 maxbuf_sz = maxbcache != 0 ? maxbcache : maxbuf * BKVASIZE;
1098 buf_sz = (long)nbuf * BKVASIZE;
1099 if (buf_sz < maxbuf_sz / TRANSIENT_DENOM *
1100 (TRANSIENT_DENOM - 1)) {
1102 * There is more KVA than memory. Do not
1103 * adjust buffer map size, and assign the rest
1104 * of maxbuf to transient map.
1106 biotmap_sz = maxbuf_sz - buf_sz;
1109 * Buffer map spans all KVA we could afford on
1110 * this platform. Give 10% (20% on i386) of
1111 * the buffer map to the transient bio map.
1113 biotmap_sz = buf_sz / TRANSIENT_DENOM;
1114 buf_sz -= biotmap_sz;
1116 if (biotmap_sz / INT_MAX > MAXPHYS)
1117 bio_transient_maxcnt = INT_MAX;
1119 bio_transient_maxcnt = biotmap_sz / MAXPHYS;
1121 * Artificially limit to 1024 simultaneous in-flight I/Os
1122 * using the transient mapping.
1124 if (bio_transient_maxcnt > 1024)
1125 bio_transient_maxcnt = 1024;
1127 nbuf = buf_sz / BKVASIZE;
1131 * swbufs are used as temporary holders for I/O, such as paging I/O.
1132 * We have no less then 16 and no more then 256.
1134 nswbuf = min(nbuf / 4, 256);
1135 TUNABLE_INT_FETCH("kern.nswbuf", &nswbuf);
1136 if (nswbuf < NSWBUF_MIN)
1137 nswbuf = NSWBUF_MIN;
1140 * Reserve space for the buffer cache buffers
1143 v = (caddr_t)(swbuf + nswbuf);
1145 v = (caddr_t)(buf + nbuf);
1150 /* Initialize the buffer subsystem. Called before use of any buffers. */
1157 KASSERT(maxbcachebuf >= MAXBSIZE,
1158 ("maxbcachebuf (%d) must be >= MAXBSIZE (%d)\n", maxbcachebuf,
1160 bq_init(&bqempty, QUEUE_EMPTY, -1, "bufq empty lock");
1161 mtx_init(&rbreqlock, "runningbufspace lock", NULL, MTX_DEF);
1162 mtx_init(&bdlock, "buffer daemon lock", NULL, MTX_DEF);
1163 mtx_init(&bdirtylock, "dirty buf lock", NULL, MTX_DEF);
1165 unmapped_buf = (caddr_t)kva_alloc(MAXPHYS);
1167 /* finally, initialize each buffer header and stick on empty q */
1168 for (i = 0; i < nbuf; i++) {
1170 bzero(bp, sizeof *bp);
1171 bp->b_flags = B_INVAL;
1172 bp->b_rcred = NOCRED;
1173 bp->b_wcred = NOCRED;
1174 bp->b_qindex = QUEUE_NONE;
1176 bp->b_subqueue = mp_maxid + 1;
1178 bp->b_data = bp->b_kvabase = unmapped_buf;
1179 LIST_INIT(&bp->b_dep);
1181 bq_insert(&bqempty, bp, false);
1185 * maxbufspace is the absolute maximum amount of buffer space we are
1186 * allowed to reserve in KVM and in real terms. The absolute maximum
1187 * is nominally used by metadata. hibufspace is the nominal maximum
1188 * used by most other requests. The differential is required to
1189 * ensure that metadata deadlocks don't occur.
1191 * maxbufspace is based on BKVASIZE. Allocating buffers larger then
1192 * this may result in KVM fragmentation which is not handled optimally
1193 * by the system. XXX This is less true with vmem. We could use
1196 maxbufspace = (long)nbuf * BKVASIZE;
1197 hibufspace = lmax(3 * maxbufspace / 4, maxbufspace - maxbcachebuf * 10);
1198 lobufspace = (hibufspace / 20) * 19; /* 95% */
1199 bufspacethresh = lobufspace + (hibufspace - lobufspace) / 2;
1202 * Note: The 16 MiB upper limit for hirunningspace was chosen
1203 * arbitrarily and may need further tuning. It corresponds to
1204 * 128 outstanding write IO requests (if IO size is 128 KiB),
1205 * which fits with many RAID controllers' tagged queuing limits.
1206 * The lower 1 MiB limit is the historical upper limit for
1209 hirunningspace = lmax(lmin(roundup(hibufspace / 64, maxbcachebuf),
1210 16 * 1024 * 1024), 1024 * 1024);
1211 lorunningspace = roundup((hirunningspace * 2) / 3, maxbcachebuf);
1214 * Limit the amount of malloc memory since it is wired permanently into
1215 * the kernel space. Even though this is accounted for in the buffer
1216 * allocation, we don't want the malloced region to grow uncontrolled.
1217 * The malloc scheme improves memory utilization significantly on
1218 * average (small) directories.
1220 maxbufmallocspace = hibufspace / 20;
1223 * Reduce the chance of a deadlock occurring by limiting the number
1224 * of delayed-write dirty buffers we allow to stack up.
1226 hidirtybuffers = nbuf / 4 + 20;
1227 dirtybufthresh = hidirtybuffers * 9 / 10;
1229 * To support extreme low-memory systems, make sure hidirtybuffers
1230 * cannot eat up all available buffer space. This occurs when our
1231 * minimum cannot be met. We try to size hidirtybuffers to 3/4 our
1232 * buffer space assuming BKVASIZE'd buffers.
1234 while ((long)hidirtybuffers * BKVASIZE > 3 * hibufspace / 4) {
1235 hidirtybuffers >>= 1;
1237 lodirtybuffers = hidirtybuffers / 2;
1240 * lofreebuffers should be sufficient to avoid stalling waiting on
1241 * buf headers under heavy utilization. The bufs in per-cpu caches
1242 * are counted as free but will be unavailable to threads executing
1245 * hifreebuffers is the free target for the bufspace daemon. This
1246 * should be set appropriately to limit work per-iteration.
1248 lofreebuffers = MIN((nbuf / 25) + (20 * mp_ncpus), 128 * mp_ncpus);
1249 hifreebuffers = (3 * lofreebuffers) / 2;
1250 numfreebuffers = nbuf;
1252 /* Setup the kva and free list allocators. */
1253 vmem_set_reclaim(buffer_arena, bufkva_reclaim);
1254 buf_zone = uma_zcache_create("buf free cache", sizeof(struct buf),
1255 NULL, NULL, NULL, NULL, buf_import, buf_release, NULL, 0);
1258 * Size the clean queue according to the amount of buffer space.
1259 * One queue per-256mb up to the max. More queues gives better
1260 * concurrency but less accurate LRU.
1262 buf_domains = MIN(howmany(maxbufspace, 256*1024*1024), BUF_DOMAINS);
1263 for (i = 0 ; i < buf_domains; i++) {
1264 struct bufdomain *bd;
1268 bd->bd_freebuffers = nbuf / buf_domains;
1269 bd->bd_hifreebuffers = hifreebuffers / buf_domains;
1270 bd->bd_lofreebuffers = lofreebuffers / buf_domains;
1271 bd->bd_bufspace = 0;
1272 bd->bd_maxbufspace = maxbufspace / buf_domains;
1273 bd->bd_hibufspace = hibufspace / buf_domains;
1274 bd->bd_lobufspace = lobufspace / buf_domains;
1275 bd->bd_bufspacethresh = bufspacethresh / buf_domains;
1276 bd->bd_numdirtybuffers = 0;
1277 bd->bd_hidirtybuffers = hidirtybuffers / buf_domains;
1278 bd->bd_lodirtybuffers = lodirtybuffers / buf_domains;
1279 bd->bd_dirtybufthresh = dirtybufthresh / buf_domains;
1280 /* Don't allow more than 2% of bufs in the per-cpu caches. */
1281 bd->bd_lim = nbuf / buf_domains / 50 / mp_ncpus;
1283 getnewbufcalls = counter_u64_alloc(M_WAITOK);
1284 getnewbufrestarts = counter_u64_alloc(M_WAITOK);
1285 mappingrestarts = counter_u64_alloc(M_WAITOK);
1286 numbufallocfails = counter_u64_alloc(M_WAITOK);
1287 notbufdflushes = counter_u64_alloc(M_WAITOK);
1288 buffreekvacnt = counter_u64_alloc(M_WAITOK);
1289 bufdefragcnt = counter_u64_alloc(M_WAITOK);
1290 bufkvaspace = counter_u64_alloc(M_WAITOK);
1295 vfs_buf_check_mapped(struct buf *bp)
1298 KASSERT(bp->b_kvabase != unmapped_buf,
1299 ("mapped buf: b_kvabase was not updated %p", bp));
1300 KASSERT(bp->b_data != unmapped_buf,
1301 ("mapped buf: b_data was not updated %p", bp));
1302 KASSERT(bp->b_data < unmapped_buf || bp->b_data >= unmapped_buf +
1303 MAXPHYS, ("b_data + b_offset unmapped %p", bp));
1307 vfs_buf_check_unmapped(struct buf *bp)
1310 KASSERT(bp->b_data == unmapped_buf,
1311 ("unmapped buf: corrupted b_data %p", bp));
1314 #define BUF_CHECK_MAPPED(bp) vfs_buf_check_mapped(bp)
1315 #define BUF_CHECK_UNMAPPED(bp) vfs_buf_check_unmapped(bp)
1317 #define BUF_CHECK_MAPPED(bp) do {} while (0)
1318 #define BUF_CHECK_UNMAPPED(bp) do {} while (0)
1322 isbufbusy(struct buf *bp)
1324 if (((bp->b_flags & B_INVAL) == 0 && BUF_ISLOCKED(bp)) ||
1325 ((bp->b_flags & (B_DELWRI | B_INVAL)) == B_DELWRI))
1331 * Shutdown the system cleanly to prepare for reboot, halt, or power off.
1334 bufshutdown(int show_busybufs)
1336 static int first_buf_printf = 1;
1338 int iter, nbusy, pbusy;
1344 * Sync filesystems for shutdown
1346 wdog_kern_pat(WD_LASTVAL);
1347 sys_sync(curthread, NULL);
1350 * With soft updates, some buffers that are
1351 * written will be remarked as dirty until other
1352 * buffers are written.
1354 for (iter = pbusy = 0; iter < 20; iter++) {
1356 for (bp = &buf[nbuf]; --bp >= buf; )
1360 if (first_buf_printf)
1361 printf("All buffers synced.");
1364 if (first_buf_printf) {
1365 printf("Syncing disks, buffers remaining... ");
1366 first_buf_printf = 0;
1368 printf("%d ", nbusy);
1373 wdog_kern_pat(WD_LASTVAL);
1374 sys_sync(curthread, NULL);
1378 * Spin for a while to allow interrupt threads to run.
1380 DELAY(50000 * iter);
1383 * Context switch several times to allow interrupt
1386 for (subiter = 0; subiter < 50 * iter; subiter++) {
1387 thread_lock(curthread);
1388 mi_switch(SW_VOL, NULL);
1389 thread_unlock(curthread);
1396 * Count only busy local buffers to prevent forcing
1397 * a fsck if we're just a client of a wedged NFS server
1400 for (bp = &buf[nbuf]; --bp >= buf; ) {
1401 if (isbufbusy(bp)) {
1403 /* XXX: This is bogus. We should probably have a BO_REMOTE flag instead */
1404 if (bp->b_dev == NULL) {
1405 TAILQ_REMOVE(&mountlist,
1406 bp->b_vp->v_mount, mnt_list);
1411 if (show_busybufs > 0) {
1413 "%d: buf:%p, vnode:%p, flags:%0x, blkno:%jd, lblkno:%jd, buflock:",
1414 nbusy, bp, bp->b_vp, bp->b_flags,
1415 (intmax_t)bp->b_blkno,
1416 (intmax_t)bp->b_lblkno);
1417 BUF_LOCKPRINTINFO(bp);
1418 if (show_busybufs > 1)
1426 * Failed to sync all blocks. Indicate this and don't
1427 * unmount filesystems (thus forcing an fsck on reboot).
1429 printf("Giving up on %d buffers\n", nbusy);
1430 DELAY(5000000); /* 5 seconds */
1432 if (!first_buf_printf)
1433 printf("Final sync complete\n");
1435 * Unmount filesystems
1437 if (panicstr == NULL)
1441 DELAY(100000); /* wait for console output to finish */
1445 bpmap_qenter(struct buf *bp)
1448 BUF_CHECK_MAPPED(bp);
1451 * bp->b_data is relative to bp->b_offset, but
1452 * bp->b_offset may be offset into the first page.
1454 bp->b_data = (caddr_t)trunc_page((vm_offset_t)bp->b_data);
1455 pmap_qenter((vm_offset_t)bp->b_data, bp->b_pages, bp->b_npages);
1456 bp->b_data = (caddr_t)((vm_offset_t)bp->b_data |
1457 (vm_offset_t)(bp->b_offset & PAGE_MASK));
1460 static inline struct bufdomain *
1461 bufdomain(struct buf *bp)
1464 return (&bdomain[bp->b_domain]);
1467 static struct bufqueue *
1468 bufqueue(struct buf *bp)
1471 switch (bp->b_qindex) {
1474 case QUEUE_SENTINEL:
1479 return (&bufdomain(bp)->bd_dirtyq);
1481 return (&bufdomain(bp)->bd_subq[bp->b_subqueue]);
1485 panic("bufqueue(%p): Unhandled type %d\n", bp, bp->b_qindex);
1489 * Return the locked bufqueue that bp is a member of.
1491 static struct bufqueue *
1492 bufqueue_acquire(struct buf *bp)
1494 struct bufqueue *bq, *nbq;
1497 * bp can be pushed from a per-cpu queue to the
1498 * cleanq while we're waiting on the lock. Retry
1499 * if the queues don't match.
1517 * Insert the buffer into the appropriate free list. Requires a
1518 * locked buffer on entry and buffer is unlocked before return.
1521 binsfree(struct buf *bp, int qindex)
1523 struct bufdomain *bd;
1524 struct bufqueue *bq;
1526 KASSERT(qindex == QUEUE_CLEAN || qindex == QUEUE_DIRTY,
1527 ("binsfree: Invalid qindex %d", qindex));
1528 BUF_ASSERT_XLOCKED(bp);
1531 * Handle delayed bremfree() processing.
1533 if (bp->b_flags & B_REMFREE) {
1534 if (bp->b_qindex == qindex) {
1535 bp->b_flags |= B_REUSE;
1536 bp->b_flags &= ~B_REMFREE;
1540 bq = bufqueue_acquire(bp);
1545 if (qindex == QUEUE_CLEAN) {
1546 if (bd->bd_lim != 0)
1547 bq = &bd->bd_subq[PCPU_GET(cpuid)];
1551 bq = &bd->bd_dirtyq;
1552 bq_insert(bq, bp, true);
1558 * Free a buffer to the buf zone once it no longer has valid contents.
1561 buf_free(struct buf *bp)
1564 if (bp->b_flags & B_REMFREE)
1566 if (bp->b_vflags & BV_BKGRDINPROG)
1567 panic("losing buffer 1");
1568 if (bp->b_rcred != NOCRED) {
1569 crfree(bp->b_rcred);
1570 bp->b_rcred = NOCRED;
1572 if (bp->b_wcred != NOCRED) {
1573 crfree(bp->b_wcred);
1574 bp->b_wcred = NOCRED;
1576 if (!LIST_EMPTY(&bp->b_dep))
1579 atomic_add_int(&bufdomain(bp)->bd_freebuffers, 1);
1581 uma_zfree(buf_zone, bp);
1587 * Import bufs into the uma cache from the buf list. The system still
1588 * expects a static array of bufs and much of the synchronization
1589 * around bufs assumes type stable storage. As a result, UMA is used
1590 * only as a per-cpu cache of bufs still maintained on a global list.
1593 buf_import(void *arg, void **store, int cnt, int domain, int flags)
1599 for (i = 0; i < cnt; i++) {
1600 bp = TAILQ_FIRST(&bqempty.bq_queue);
1603 bq_remove(&bqempty, bp);
1606 BQ_UNLOCK(&bqempty);
1614 * Release bufs from the uma cache back to the buffer queues.
1617 buf_release(void *arg, void **store, int cnt)
1619 struct bufqueue *bq;
1625 for (i = 0; i < cnt; i++) {
1627 /* Inline bq_insert() to batch locking. */
1628 TAILQ_INSERT_TAIL(&bq->bq_queue, bp, b_freelist);
1629 bp->b_flags &= ~(B_AGE | B_REUSE);
1631 bp->b_qindex = bq->bq_index;
1639 * Allocate an empty buffer header.
1642 buf_alloc(struct bufdomain *bd)
1648 * We can only run out of bufs in the buf zone if the average buf
1649 * is less than BKVASIZE. In this case the actual wait/block will
1650 * come from buf_reycle() failing to flush one of these small bufs.
1653 freebufs = atomic_fetchadd_int(&bd->bd_freebuffers, -1);
1655 bp = uma_zalloc(buf_zone, M_NOWAIT);
1657 atomic_fetchadd_int(&bd->bd_freebuffers, 1);
1658 bufspace_daemon_wakeup(bd);
1659 counter_u64_add(numbufallocfails, 1);
1663 * Wake-up the bufspace daemon on transition below threshold.
1665 if (freebufs == bd->bd_lofreebuffers)
1666 bufspace_daemon_wakeup(bd);
1668 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0)
1669 panic("getnewbuf_empty: Locked buf %p on free queue.", bp);
1671 KASSERT(bp->b_vp == NULL,
1672 ("bp: %p still has vnode %p.", bp, bp->b_vp));
1673 KASSERT((bp->b_flags & (B_DELWRI | B_NOREUSE)) == 0,
1674 ("invalid buffer %p flags %#x", bp, bp->b_flags));
1675 KASSERT((bp->b_xflags & (BX_VNCLEAN|BX_VNDIRTY)) == 0,
1676 ("bp: %p still on a buffer list. xflags %X", bp, bp->b_xflags));
1677 KASSERT(bp->b_npages == 0,
1678 ("bp: %p still has %d vm pages\n", bp, bp->b_npages));
1679 KASSERT(bp->b_kvasize == 0, ("bp: %p still has kva\n", bp));
1680 KASSERT(bp->b_bufsize == 0, ("bp: %p still has bufspace\n", bp));
1682 bp->b_domain = BD_DOMAIN(bd);
1688 bp->b_blkno = bp->b_lblkno = 0;
1689 bp->b_offset = NOOFFSET;
1695 bp->b_dirtyoff = bp->b_dirtyend = 0;
1696 bp->b_bufobj = NULL;
1697 bp->b_data = bp->b_kvabase = unmapped_buf;
1698 bp->b_fsprivate1 = NULL;
1699 bp->b_fsprivate2 = NULL;
1700 bp->b_fsprivate3 = NULL;
1701 LIST_INIT(&bp->b_dep);
1709 * Free a buffer from the given bufqueue. kva controls whether the
1710 * freed buf must own some kva resources. This is used for
1714 buf_recycle(struct bufdomain *bd, bool kva)
1716 struct bufqueue *bq;
1717 struct buf *bp, *nbp;
1720 counter_u64_add(bufdefragcnt, 1);
1724 KASSERT(BQ_LOCKPTR(bq) == BD_LOCKPTR(bd),
1725 ("buf_recycle: Locks don't match"));
1726 nbp = TAILQ_FIRST(&bq->bq_queue);
1729 * Run scan, possibly freeing data and/or kva mappings on the fly
1732 while ((bp = nbp) != NULL) {
1734 * Calculate next bp (we can only use it if we do not
1735 * release the bqlock).
1737 nbp = TAILQ_NEXT(bp, b_freelist);
1740 * If we are defragging then we need a buffer with
1741 * some kva to reclaim.
1743 if (kva && bp->b_kvasize == 0)
1746 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0)
1750 * Implement a second chance algorithm for frequently
1753 if ((bp->b_flags & B_REUSE) != 0) {
1754 TAILQ_REMOVE(&bq->bq_queue, bp, b_freelist);
1755 TAILQ_INSERT_TAIL(&bq->bq_queue, bp, b_freelist);
1756 bp->b_flags &= ~B_REUSE;
1762 * Skip buffers with background writes in progress.
1764 if ((bp->b_vflags & BV_BKGRDINPROG) != 0) {
1769 KASSERT(bp->b_qindex == QUEUE_CLEAN,
1770 ("buf_recycle: inconsistent queue %d bp %p",
1772 KASSERT(bp->b_domain == BD_DOMAIN(bd),
1773 ("getnewbuf: queue domain %d doesn't match request %d",
1774 bp->b_domain, (int)BD_DOMAIN(bd)));
1776 * NOTE: nbp is now entirely invalid. We can only restart
1777 * the scan from this point on.
1783 * Requeue the background write buffer with error and
1786 if ((bp->b_vflags & BV_BKGRDERR) != 0) {
1789 nbp = TAILQ_FIRST(&bq->bq_queue);
1792 bp->b_flags |= B_INVAL;
1805 * Mark the buffer for removal from the appropriate free list.
1809 bremfree(struct buf *bp)
1812 CTR3(KTR_BUF, "bremfree(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
1813 KASSERT((bp->b_flags & B_REMFREE) == 0,
1814 ("bremfree: buffer %p already marked for delayed removal.", bp));
1815 KASSERT(bp->b_qindex != QUEUE_NONE,
1816 ("bremfree: buffer %p not on a queue.", bp));
1817 BUF_ASSERT_XLOCKED(bp);
1819 bp->b_flags |= B_REMFREE;
1825 * Force an immediate removal from a free list. Used only in nfs when
1826 * it abuses the b_freelist pointer.
1829 bremfreef(struct buf *bp)
1831 struct bufqueue *bq;
1833 bq = bufqueue_acquire(bp);
1839 bq_init(struct bufqueue *bq, int qindex, int subqueue, const char *lockname)
1842 mtx_init(&bq->bq_lock, lockname, NULL, MTX_DEF);
1843 TAILQ_INIT(&bq->bq_queue);
1845 bq->bq_index = qindex;
1846 bq->bq_subqueue = subqueue;
1850 bd_init(struct bufdomain *bd)
1855 domain = bd - bdomain;
1856 bd->bd_cleanq = &bd->bd_subq[mp_maxid + 1];
1857 bq_init(bd->bd_cleanq, QUEUE_CLEAN, mp_maxid + 1, "bufq clean lock");
1858 bq_init(&bd->bd_dirtyq, QUEUE_DIRTY, -1, "bufq dirty lock");
1859 for (i = 0; i <= mp_maxid; i++)
1860 bq_init(&bd->bd_subq[i], QUEUE_CLEAN, i,
1861 "bufq clean subqueue lock");
1862 mtx_init(&bd->bd_run_lock, "bufspace daemon run lock", NULL, MTX_DEF);
1868 * Removes a buffer from the free list, must be called with the
1869 * correct qlock held.
1872 bq_remove(struct bufqueue *bq, struct buf *bp)
1875 CTR3(KTR_BUF, "bq_remove(%p) vp %p flags %X",
1876 bp, bp->b_vp, bp->b_flags);
1877 KASSERT(bp->b_qindex != QUEUE_NONE,
1878 ("bq_remove: buffer %p not on a queue.", bp));
1879 KASSERT(bufqueue(bp) == bq,
1880 ("bq_remove: Remove buffer %p from wrong queue.", bp));
1882 BQ_ASSERT_LOCKED(bq);
1883 if (bp->b_qindex != QUEUE_EMPTY) {
1884 BUF_ASSERT_XLOCKED(bp);
1886 KASSERT(bq->bq_len >= 1,
1887 ("queue %d underflow", bp->b_qindex));
1888 TAILQ_REMOVE(&bq->bq_queue, bp, b_freelist);
1890 bp->b_qindex = QUEUE_NONE;
1891 bp->b_flags &= ~(B_REMFREE | B_REUSE);
1895 bd_flush(struct bufdomain *bd, struct bufqueue *bq)
1899 BQ_ASSERT_LOCKED(bq);
1900 if (bq != bd->bd_cleanq) {
1902 while ((bp = TAILQ_FIRST(&bq->bq_queue)) != NULL) {
1903 TAILQ_REMOVE(&bq->bq_queue, bp, b_freelist);
1904 TAILQ_INSERT_TAIL(&bd->bd_cleanq->bq_queue, bp,
1906 bp->b_subqueue = bd->bd_cleanq->bq_subqueue;
1908 bd->bd_cleanq->bq_len += bq->bq_len;
1911 if (bd->bd_wanted) {
1913 wakeup(&bd->bd_wanted);
1915 if (bq != bd->bd_cleanq)
1920 bd_flushall(struct bufdomain *bd)
1922 struct bufqueue *bq;
1926 if (bd->bd_lim == 0)
1929 for (i = 0; i <= mp_maxid; i++) {
1930 bq = &bd->bd_subq[i];
1931 if (bq->bq_len == 0)
1943 bq_insert(struct bufqueue *bq, struct buf *bp, bool unlock)
1945 struct bufdomain *bd;
1947 if (bp->b_qindex != QUEUE_NONE)
1948 panic("bq_insert: free buffer %p onto another queue?", bp);
1951 if (bp->b_flags & B_AGE) {
1952 /* Place this buf directly on the real queue. */
1953 if (bq->bq_index == QUEUE_CLEAN)
1956 TAILQ_INSERT_HEAD(&bq->bq_queue, bp, b_freelist);
1959 TAILQ_INSERT_TAIL(&bq->bq_queue, bp, b_freelist);
1961 bp->b_flags &= ~(B_AGE | B_REUSE);
1963 bp->b_qindex = bq->bq_index;
1964 bp->b_subqueue = bq->bq_subqueue;
1967 * Unlock before we notify so that we don't wakeup a waiter that
1968 * fails a trylock on the buf and sleeps again.
1973 if (bp->b_qindex == QUEUE_CLEAN) {
1975 * Flush the per-cpu queue and notify any waiters.
1977 if (bd->bd_wanted || (bq != bd->bd_cleanq &&
1978 bq->bq_len >= bd->bd_lim))
1987 * Free the kva allocation for a buffer.
1991 bufkva_free(struct buf *bp)
1995 if (bp->b_kvasize == 0) {
1996 KASSERT(bp->b_kvabase == unmapped_buf &&
1997 bp->b_data == unmapped_buf,
1998 ("Leaked KVA space on %p", bp));
1999 } else if (buf_mapped(bp))
2000 BUF_CHECK_MAPPED(bp);
2002 BUF_CHECK_UNMAPPED(bp);
2004 if (bp->b_kvasize == 0)
2007 vmem_free(buffer_arena, (vm_offset_t)bp->b_kvabase, bp->b_kvasize);
2008 counter_u64_add(bufkvaspace, -bp->b_kvasize);
2009 counter_u64_add(buffreekvacnt, 1);
2010 bp->b_data = bp->b_kvabase = unmapped_buf;
2017 * Allocate the buffer KVA and set b_kvasize and b_kvabase.
2020 bufkva_alloc(struct buf *bp, int maxsize, int gbflags)
2025 KASSERT((gbflags & GB_UNMAPPED) == 0 || (gbflags & GB_KVAALLOC) != 0,
2026 ("Invalid gbflags 0x%x in %s", gbflags, __func__));
2031 error = vmem_alloc(buffer_arena, maxsize, M_BESTFIT | M_NOWAIT, &addr);
2034 * Buffer map is too fragmented. Request the caller
2035 * to defragment the map.
2039 bp->b_kvabase = (caddr_t)addr;
2040 bp->b_kvasize = maxsize;
2041 counter_u64_add(bufkvaspace, bp->b_kvasize);
2042 if ((gbflags & GB_UNMAPPED) != 0) {
2043 bp->b_data = unmapped_buf;
2044 BUF_CHECK_UNMAPPED(bp);
2046 bp->b_data = bp->b_kvabase;
2047 BUF_CHECK_MAPPED(bp);
2055 * Reclaim buffer kva by freeing buffers holding kva. This is a vmem
2056 * callback that fires to avoid returning failure.
2059 bufkva_reclaim(vmem_t *vmem, int flags)
2066 for (i = 0; i < 5; i++) {
2067 for (q = 0; q < buf_domains; q++)
2068 if (buf_recycle(&bdomain[q], true) != 0)
2077 * Attempt to initiate asynchronous I/O on read-ahead blocks. We must
2078 * clear BIO_ERROR and B_INVAL prior to initiating I/O . If B_CACHE is set,
2079 * the buffer is valid and we do not have to do anything.
2082 breada(struct vnode * vp, daddr_t * rablkno, int * rabsize, int cnt,
2083 struct ucred * cred, int flags, void (*ckhashfunc)(struct buf *))
2088 for (i = 0; i < cnt; i++, rablkno++, rabsize++) {
2089 if (inmem(vp, *rablkno))
2091 rabp = getblk(vp, *rablkno, *rabsize, 0, 0, 0);
2092 if ((rabp->b_flags & B_CACHE) != 0) {
2096 if (!TD_IS_IDLETHREAD(curthread)) {
2100 racct_add_buf(curproc, rabp, 0);
2101 PROC_UNLOCK(curproc);
2104 curthread->td_ru.ru_inblock++;
2106 rabp->b_flags |= B_ASYNC;
2107 rabp->b_flags &= ~B_INVAL;
2108 if ((flags & GB_CKHASH) != 0) {
2109 rabp->b_flags |= B_CKHASH;
2110 rabp->b_ckhashcalc = ckhashfunc;
2112 rabp->b_ioflags &= ~BIO_ERROR;
2113 rabp->b_iocmd = BIO_READ;
2114 if (rabp->b_rcred == NOCRED && cred != NOCRED)
2115 rabp->b_rcred = crhold(cred);
2116 vfs_busy_pages(rabp, 0);
2118 rabp->b_iooffset = dbtob(rabp->b_blkno);
2124 * Entry point for bread() and breadn() via #defines in sys/buf.h.
2126 * Get a buffer with the specified data. Look in the cache first. We
2127 * must clear BIO_ERROR and B_INVAL prior to initiating I/O. If B_CACHE
2128 * is set, the buffer is valid and we do not have to do anything, see
2129 * getblk(). Also starts asynchronous I/O on read-ahead blocks.
2131 * Always return a NULL buffer pointer (in bpp) when returning an error.
2134 breadn_flags(struct vnode *vp, daddr_t blkno, int size, daddr_t *rablkno,
2135 int *rabsize, int cnt, struct ucred *cred, int flags,
2136 void (*ckhashfunc)(struct buf *), struct buf **bpp)
2141 CTR3(KTR_BUF, "breadn(%p, %jd, %d)", vp, blkno, size);
2143 * Can only return NULL if GB_LOCK_NOWAIT flag is specified.
2145 *bpp = bp = getblk(vp, blkno, size, 0, 0, flags);
2150 * If not found in cache, do some I/O
2153 if ((bp->b_flags & B_CACHE) == 0) {
2154 if (!TD_IS_IDLETHREAD(curthread)) {
2158 racct_add_buf(curproc, bp, 0);
2159 PROC_UNLOCK(curproc);
2162 curthread->td_ru.ru_inblock++;
2164 bp->b_iocmd = BIO_READ;
2165 bp->b_flags &= ~B_INVAL;
2166 if ((flags & GB_CKHASH) != 0) {
2167 bp->b_flags |= B_CKHASH;
2168 bp->b_ckhashcalc = ckhashfunc;
2170 bp->b_ioflags &= ~BIO_ERROR;
2171 if (bp->b_rcred == NOCRED && cred != NOCRED)
2172 bp->b_rcred = crhold(cred);
2173 vfs_busy_pages(bp, 0);
2174 bp->b_iooffset = dbtob(bp->b_blkno);
2180 * Attempt to initiate asynchronous I/O on read-ahead blocks.
2182 breada(vp, rablkno, rabsize, cnt, cred, flags, ckhashfunc);
2196 * Write, release buffer on completion. (Done by iodone
2197 * if async). Do not bother writing anything if the buffer
2200 * Note that we set B_CACHE here, indicating that buffer is
2201 * fully valid and thus cacheable. This is true even of NFS
2202 * now so we set it generally. This could be set either here
2203 * or in biodone() since the I/O is synchronous. We put it
2207 bufwrite(struct buf *bp)
2214 CTR3(KTR_BUF, "bufwrite(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
2215 if ((bp->b_bufobj->bo_flag & BO_DEAD) != 0) {
2216 bp->b_flags |= B_INVAL | B_RELBUF;
2217 bp->b_flags &= ~B_CACHE;
2221 if (bp->b_flags & B_INVAL) {
2226 if (bp->b_flags & B_BARRIER)
2229 oldflags = bp->b_flags;
2231 BUF_ASSERT_HELD(bp);
2233 KASSERT(!(bp->b_vflags & BV_BKGRDINPROG),
2234 ("FFS background buffer should not get here %p", bp));
2238 vp_md = vp->v_vflag & VV_MD;
2243 * Mark the buffer clean. Increment the bufobj write count
2244 * before bundirty() call, to prevent other thread from seeing
2245 * empty dirty list and zero counter for writes in progress,
2246 * falsely indicating that the bufobj is clean.
2248 bufobj_wref(bp->b_bufobj);
2251 bp->b_flags &= ~B_DONE;
2252 bp->b_ioflags &= ~BIO_ERROR;
2253 bp->b_flags |= B_CACHE;
2254 bp->b_iocmd = BIO_WRITE;
2256 vfs_busy_pages(bp, 1);
2259 * Normal bwrites pipeline writes
2261 bp->b_runningbufspace = bp->b_bufsize;
2262 space = atomic_fetchadd_long(&runningbufspace, bp->b_runningbufspace);
2264 if (!TD_IS_IDLETHREAD(curthread)) {
2268 racct_add_buf(curproc, bp, 1);
2269 PROC_UNLOCK(curproc);
2272 curthread->td_ru.ru_oublock++;
2274 if (oldflags & B_ASYNC)
2276 bp->b_iooffset = dbtob(bp->b_blkno);
2277 buf_track(bp, __func__);
2280 if ((oldflags & B_ASYNC) == 0) {
2281 int rtval = bufwait(bp);
2284 } else if (space > hirunningspace) {
2286 * don't allow the async write to saturate the I/O
2287 * system. We will not deadlock here because
2288 * we are blocking waiting for I/O that is already in-progress
2289 * to complete. We do not block here if it is the update
2290 * or syncer daemon trying to clean up as that can lead
2293 if ((curthread->td_pflags & TDP_NORUNNINGBUF) == 0 && !vp_md)
2294 waitrunningbufspace();
2301 bufbdflush(struct bufobj *bo, struct buf *bp)
2305 if (bo->bo_dirty.bv_cnt > dirtybufthresh + 10) {
2306 (void) VOP_FSYNC(bp->b_vp, MNT_NOWAIT, curthread);
2308 } else if (bo->bo_dirty.bv_cnt > dirtybufthresh) {
2311 * Try to find a buffer to flush.
2313 TAILQ_FOREACH(nbp, &bo->bo_dirty.bv_hd, b_bobufs) {
2314 if ((nbp->b_vflags & BV_BKGRDINPROG) ||
2316 LK_EXCLUSIVE | LK_NOWAIT, NULL))
2319 panic("bdwrite: found ourselves");
2321 /* Don't countdeps with the bo lock held. */
2322 if (buf_countdeps(nbp, 0)) {
2327 if (nbp->b_flags & B_CLUSTEROK) {
2328 vfs_bio_awrite(nbp);
2333 dirtybufferflushes++;
2342 * Delayed write. (Buffer is marked dirty). Do not bother writing
2343 * anything if the buffer is marked invalid.
2345 * Note that since the buffer must be completely valid, we can safely
2346 * set B_CACHE. In fact, we have to set B_CACHE here rather then in
2347 * biodone() in order to prevent getblk from writing the buffer
2348 * out synchronously.
2351 bdwrite(struct buf *bp)
2353 struct thread *td = curthread;
2357 CTR3(KTR_BUF, "bdwrite(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
2358 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp));
2359 KASSERT((bp->b_flags & B_BARRIER) == 0,
2360 ("Barrier request in delayed write %p", bp));
2361 BUF_ASSERT_HELD(bp);
2363 if (bp->b_flags & B_INVAL) {
2369 * If we have too many dirty buffers, don't create any more.
2370 * If we are wildly over our limit, then force a complete
2371 * cleanup. Otherwise, just keep the situation from getting
2372 * out of control. Note that we have to avoid a recursive
2373 * disaster and not try to clean up after our own cleanup!
2377 if ((td->td_pflags & (TDP_COWINPROGRESS|TDP_INBDFLUSH)) == 0) {
2378 td->td_pflags |= TDP_INBDFLUSH;
2380 td->td_pflags &= ~TDP_INBDFLUSH;
2386 * Set B_CACHE, indicating that the buffer is fully valid. This is
2387 * true even of NFS now.
2389 bp->b_flags |= B_CACHE;
2392 * This bmap keeps the system from needing to do the bmap later,
2393 * perhaps when the system is attempting to do a sync. Since it
2394 * is likely that the indirect block -- or whatever other datastructure
2395 * that the filesystem needs is still in memory now, it is a good
2396 * thing to do this. Note also, that if the pageout daemon is
2397 * requesting a sync -- there might not be enough memory to do
2398 * the bmap then... So, this is important to do.
2400 if (vp->v_type != VCHR && bp->b_lblkno == bp->b_blkno) {
2401 VOP_BMAP(vp, bp->b_lblkno, NULL, &bp->b_blkno, NULL, NULL);
2404 buf_track(bp, __func__);
2407 * Set the *dirty* buffer range based upon the VM system dirty
2410 * Mark the buffer pages as clean. We need to do this here to
2411 * satisfy the vnode_pager and the pageout daemon, so that it
2412 * thinks that the pages have been "cleaned". Note that since
2413 * the pages are in a delayed write buffer -- the VFS layer
2414 * "will" see that the pages get written out on the next sync,
2415 * or perhaps the cluster will be completed.
2417 vfs_clean_pages_dirty_buf(bp);
2421 * note: we cannot initiate I/O from a bdwrite even if we wanted to,
2422 * due to the softdep code.
2429 * Turn buffer into delayed write request. We must clear BIO_READ and
2430 * B_RELBUF, and we must set B_DELWRI. We reassign the buffer to
2431 * itself to properly update it in the dirty/clean lists. We mark it
2432 * B_DONE to ensure that any asynchronization of the buffer properly
2433 * clears B_DONE ( else a panic will occur later ).
2435 * bdirty() is kinda like bdwrite() - we have to clear B_INVAL which
2436 * might have been set pre-getblk(). Unlike bwrite/bdwrite, bdirty()
2437 * should only be called if the buffer is known-good.
2439 * Since the buffer is not on a queue, we do not update the numfreebuffers
2442 * The buffer must be on QUEUE_NONE.
2445 bdirty(struct buf *bp)
2448 CTR3(KTR_BUF, "bdirty(%p) vp %p flags %X",
2449 bp, bp->b_vp, bp->b_flags);
2450 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp));
2451 KASSERT(bp->b_flags & B_REMFREE || bp->b_qindex == QUEUE_NONE,
2452 ("bdirty: buffer %p still on queue %d", bp, bp->b_qindex));
2453 BUF_ASSERT_HELD(bp);
2454 bp->b_flags &= ~(B_RELBUF);
2455 bp->b_iocmd = BIO_WRITE;
2457 if ((bp->b_flags & B_DELWRI) == 0) {
2458 bp->b_flags |= /* XXX B_DONE | */ B_DELWRI;
2467 * Clear B_DELWRI for buffer.
2469 * Since the buffer is not on a queue, we do not update the numfreebuffers
2472 * The buffer must be on QUEUE_NONE.
2476 bundirty(struct buf *bp)
2479 CTR3(KTR_BUF, "bundirty(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
2480 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp));
2481 KASSERT(bp->b_flags & B_REMFREE || bp->b_qindex == QUEUE_NONE,
2482 ("bundirty: buffer %p still on queue %d", bp, bp->b_qindex));
2483 BUF_ASSERT_HELD(bp);
2485 if (bp->b_flags & B_DELWRI) {
2486 bp->b_flags &= ~B_DELWRI;
2491 * Since it is now being written, we can clear its deferred write flag.
2493 bp->b_flags &= ~B_DEFERRED;
2499 * Asynchronous write. Start output on a buffer, but do not wait for
2500 * it to complete. The buffer is released when the output completes.
2502 * bwrite() ( or the VOP routine anyway ) is responsible for handling
2503 * B_INVAL buffers. Not us.
2506 bawrite(struct buf *bp)
2509 bp->b_flags |= B_ASYNC;
2516 * Asynchronous barrier write. Start output on a buffer, but do not
2517 * wait for it to complete. Place a write barrier after this write so
2518 * that this buffer and all buffers written before it are committed to
2519 * the disk before any buffers written after this write are committed
2520 * to the disk. The buffer is released when the output completes.
2523 babarrierwrite(struct buf *bp)
2526 bp->b_flags |= B_ASYNC | B_BARRIER;
2533 * Synchronous barrier write. Start output on a buffer and wait for
2534 * it to complete. Place a write barrier after this write so that
2535 * this buffer and all buffers written before it are committed to
2536 * the disk before any buffers written after this write are committed
2537 * to the disk. The buffer is released when the output completes.
2540 bbarrierwrite(struct buf *bp)
2543 bp->b_flags |= B_BARRIER;
2544 return (bwrite(bp));
2550 * Called prior to the locking of any vnodes when we are expecting to
2551 * write. We do not want to starve the buffer cache with too many
2552 * dirty buffers so we block here. By blocking prior to the locking
2553 * of any vnodes we attempt to avoid the situation where a locked vnode
2554 * prevents the various system daemons from flushing related buffers.
2560 if (buf_dirty_count_severe()) {
2561 mtx_lock(&bdirtylock);
2562 while (buf_dirty_count_severe()) {
2564 msleep(&bdirtywait, &bdirtylock, (PRIBIO + 4),
2567 mtx_unlock(&bdirtylock);
2572 * Return true if we have too many dirty buffers.
2575 buf_dirty_count_severe(void)
2578 return (!BIT_EMPTY(BUF_DOMAINS, &bdhidirty));
2584 * Release a busy buffer and, if requested, free its resources. The
2585 * buffer will be stashed in the appropriate bufqueue[] allowing it
2586 * to be accessed later as a cache entity or reused for other purposes.
2589 brelse(struct buf *bp)
2591 struct mount *v_mnt;
2595 * Many functions erroneously call brelse with a NULL bp under rare
2596 * error conditions. Simply return when called with a NULL bp.
2600 CTR3(KTR_BUF, "brelse(%p) vp %p flags %X",
2601 bp, bp->b_vp, bp->b_flags);
2602 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)),
2603 ("brelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp));
2604 KASSERT((bp->b_flags & B_VMIO) != 0 || (bp->b_flags & B_NOREUSE) == 0,
2605 ("brelse: non-VMIO buffer marked NOREUSE"));
2607 if (BUF_LOCKRECURSED(bp)) {
2609 * Do not process, in particular, do not handle the
2610 * B_INVAL/B_RELBUF and do not release to free list.
2616 if (bp->b_flags & B_MANAGED) {
2621 if ((bp->b_vflags & (BV_BKGRDINPROG | BV_BKGRDERR)) == BV_BKGRDERR) {
2622 BO_LOCK(bp->b_bufobj);
2623 bp->b_vflags &= ~BV_BKGRDERR;
2624 BO_UNLOCK(bp->b_bufobj);
2627 if (bp->b_iocmd == BIO_WRITE && (bp->b_ioflags & BIO_ERROR) &&
2628 (bp->b_error != ENXIO || !LIST_EMPTY(&bp->b_dep)) &&
2629 !(bp->b_flags & B_INVAL)) {
2631 * Failed write, redirty. All errors except ENXIO (which
2632 * means the device is gone) are treated as being
2635 * XXX Treating EIO as transient is not correct; the
2636 * contract with the local storage device drivers is that
2637 * they will only return EIO once the I/O is no longer
2638 * retriable. Network I/O also respects this through the
2639 * guarantees of TCP and/or the internal retries of NFS.
2640 * ENOMEM might be transient, but we also have no way of
2641 * knowing when its ok to retry/reschedule. In general,
2642 * this entire case should be made obsolete through better
2643 * error handling/recovery and resource scheduling.
2645 * Do this also for buffers that failed with ENXIO, but have
2646 * non-empty dependencies - the soft updates code might need
2647 * to access the buffer to untangle them.
2649 * Must clear BIO_ERROR to prevent pages from being scrapped.
2651 bp->b_ioflags &= ~BIO_ERROR;
2653 } else if ((bp->b_flags & (B_NOCACHE | B_INVAL)) ||
2654 (bp->b_ioflags & BIO_ERROR) || (bp->b_bufsize <= 0)) {
2656 * Either a failed read I/O, or we were asked to free or not
2657 * cache the buffer, or we failed to write to a device that's
2658 * no longer present.
2660 bp->b_flags |= B_INVAL;
2661 if (!LIST_EMPTY(&bp->b_dep))
2663 if (bp->b_flags & B_DELWRI)
2665 bp->b_flags &= ~(B_DELWRI | B_CACHE);
2666 if ((bp->b_flags & B_VMIO) == 0) {
2674 * We must clear B_RELBUF if B_DELWRI is set. If vfs_vmio_truncate()
2675 * is called with B_DELWRI set, the underlying pages may wind up
2676 * getting freed causing a previous write (bdwrite()) to get 'lost'
2677 * because pages associated with a B_DELWRI bp are marked clean.
2679 * We still allow the B_INVAL case to call vfs_vmio_truncate(), even
2680 * if B_DELWRI is set.
2682 if (bp->b_flags & B_DELWRI)
2683 bp->b_flags &= ~B_RELBUF;
2686 * VMIO buffer rundown. It is not very necessary to keep a VMIO buffer
2687 * constituted, not even NFS buffers now. Two flags effect this. If
2688 * B_INVAL, the struct buf is invalidated but the VM object is kept
2689 * around ( i.e. so it is trivial to reconstitute the buffer later ).
2691 * If BIO_ERROR or B_NOCACHE is set, pages in the VM object will be
2692 * invalidated. BIO_ERROR cannot be set for a failed write unless the
2693 * buffer is also B_INVAL because it hits the re-dirtying code above.
2695 * Normally we can do this whether a buffer is B_DELWRI or not. If
2696 * the buffer is an NFS buffer, it is tracking piecemeal writes or
2697 * the commit state and we cannot afford to lose the buffer. If the
2698 * buffer has a background write in progress, we need to keep it
2699 * around to prevent it from being reconstituted and starting a second
2703 v_mnt = bp->b_vp != NULL ? bp->b_vp->v_mount : NULL;
2705 if ((bp->b_flags & B_VMIO) && (bp->b_flags & B_NOCACHE ||
2706 (bp->b_ioflags & BIO_ERROR && bp->b_iocmd == BIO_READ)) &&
2707 (v_mnt == NULL || (v_mnt->mnt_vfc->vfc_flags & VFCF_NETWORK) == 0 ||
2708 vn_isdisk(bp->b_vp, NULL) || (bp->b_flags & B_DELWRI) == 0)) {
2709 vfs_vmio_invalidate(bp);
2713 if ((bp->b_flags & (B_INVAL | B_RELBUF)) != 0 ||
2714 (bp->b_flags & (B_DELWRI | B_NOREUSE)) == B_NOREUSE) {
2716 bp->b_flags &= ~B_NOREUSE;
2717 if (bp->b_vp != NULL)
2722 * If the buffer has junk contents signal it and eventually
2723 * clean up B_DELWRI and diassociate the vnode so that gbincore()
2726 if (bp->b_bufsize == 0 || (bp->b_ioflags & BIO_ERROR) != 0 ||
2727 (bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF)) != 0)
2728 bp->b_flags |= B_INVAL;
2729 if (bp->b_flags & B_INVAL) {
2730 if (bp->b_flags & B_DELWRI)
2736 buf_track(bp, __func__);
2738 /* buffers with no memory */
2739 if (bp->b_bufsize == 0) {
2743 /* buffers with junk contents */
2744 if (bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF) ||
2745 (bp->b_ioflags & BIO_ERROR)) {
2746 bp->b_xflags &= ~(BX_BKGRDWRITE | BX_ALTDATA);
2747 if (bp->b_vflags & BV_BKGRDINPROG)
2748 panic("losing buffer 2");
2749 qindex = QUEUE_CLEAN;
2750 bp->b_flags |= B_AGE;
2751 /* remaining buffers */
2752 } else if (bp->b_flags & B_DELWRI)
2753 qindex = QUEUE_DIRTY;
2755 qindex = QUEUE_CLEAN;
2757 if ((bp->b_flags & B_DELWRI) == 0 && (bp->b_xflags & BX_VNDIRTY))
2758 panic("brelse: not dirty");
2760 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_RELBUF | B_DIRECT);
2761 /* binsfree unlocks bp. */
2762 binsfree(bp, qindex);
2766 * Release a buffer back to the appropriate queue but do not try to free
2767 * it. The buffer is expected to be used again soon.
2769 * bqrelse() is used by bdwrite() to requeue a delayed write, and used by
2770 * biodone() to requeue an async I/O on completion. It is also used when
2771 * known good buffers need to be requeued but we think we may need the data
2774 * XXX we should be able to leave the B_RELBUF hint set on completion.
2777 bqrelse(struct buf *bp)
2781 CTR3(KTR_BUF, "bqrelse(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
2782 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)),
2783 ("bqrelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp));
2785 qindex = QUEUE_NONE;
2786 if (BUF_LOCKRECURSED(bp)) {
2787 /* do not release to free list */
2791 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF);
2793 if (bp->b_flags & B_MANAGED) {
2794 if (bp->b_flags & B_REMFREE)
2799 /* buffers with stale but valid contents */
2800 if ((bp->b_flags & B_DELWRI) != 0 || (bp->b_vflags & (BV_BKGRDINPROG |
2801 BV_BKGRDERR)) == BV_BKGRDERR) {
2802 BO_LOCK(bp->b_bufobj);
2803 bp->b_vflags &= ~BV_BKGRDERR;
2804 BO_UNLOCK(bp->b_bufobj);
2805 qindex = QUEUE_DIRTY;
2807 if ((bp->b_flags & B_DELWRI) == 0 &&
2808 (bp->b_xflags & BX_VNDIRTY))
2809 panic("bqrelse: not dirty");
2810 if ((bp->b_flags & B_NOREUSE) != 0) {
2814 qindex = QUEUE_CLEAN;
2816 buf_track(bp, __func__);
2817 /* binsfree unlocks bp. */
2818 binsfree(bp, qindex);
2822 buf_track(bp, __func__);
2828 * Complete I/O to a VMIO backed page. Validate the pages as appropriate,
2829 * restore bogus pages.
2832 vfs_vmio_iodone(struct buf *bp)
2838 int i, iosize, resid;
2841 obj = bp->b_bufobj->bo_object;
2842 KASSERT(obj->paging_in_progress >= bp->b_npages,
2843 ("vfs_vmio_iodone: paging in progress(%d) < b_npages(%d)",
2844 obj->paging_in_progress, bp->b_npages));
2847 KASSERT(vp->v_holdcnt > 0,
2848 ("vfs_vmio_iodone: vnode %p has zero hold count", vp));
2849 KASSERT(vp->v_object != NULL,
2850 ("vfs_vmio_iodone: vnode %p has no vm_object", vp));
2852 foff = bp->b_offset;
2853 KASSERT(bp->b_offset != NOOFFSET,
2854 ("vfs_vmio_iodone: bp %p has no buffer offset", bp));
2857 iosize = bp->b_bcount - bp->b_resid;
2858 VM_OBJECT_WLOCK(obj);
2859 for (i = 0; i < bp->b_npages; i++) {
2860 resid = ((foff + PAGE_SIZE) & ~(off_t)PAGE_MASK) - foff;
2865 * cleanup bogus pages, restoring the originals
2868 if (m == bogus_page) {
2870 m = vm_page_lookup(obj, OFF_TO_IDX(foff));
2872 panic("biodone: page disappeared!");
2874 } else if ((bp->b_iocmd == BIO_READ) && resid > 0) {
2876 * In the write case, the valid and clean bits are
2877 * already changed correctly ( see bdwrite() ), so we
2878 * only need to do this here in the read case.
2880 KASSERT((m->dirty & vm_page_bits(foff & PAGE_MASK,
2881 resid)) == 0, ("vfs_vmio_iodone: page %p "
2882 "has unexpected dirty bits", m));
2883 vfs_page_set_valid(bp, foff, m);
2885 KASSERT(OFF_TO_IDX(foff) == m->pindex,
2886 ("vfs_vmio_iodone: foff(%jd)/pindex(%ju) mismatch",
2887 (intmax_t)foff, (uintmax_t)m->pindex));
2890 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK;
2893 vm_object_pip_wakeupn(obj, bp->b_npages);
2894 VM_OBJECT_WUNLOCK(obj);
2895 if (bogus && buf_mapped(bp)) {
2896 BUF_CHECK_MAPPED(bp);
2897 pmap_qenter(trunc_page((vm_offset_t)bp->b_data),
2898 bp->b_pages, bp->b_npages);
2903 * Unwire a page held by a buf and either free it or update the page queues to
2904 * reflect its recent use.
2907 vfs_vmio_unwire(struct buf *bp, vm_page_t m)
2912 if (vm_page_unwire_noq(m)) {
2913 if ((bp->b_flags & B_DIRECT) != 0)
2914 freed = vm_page_try_to_free(m);
2919 * Use a racy check of the valid bits to determine
2920 * whether we can accelerate reclamation of the page.
2921 * The valid bits will be stable unless the page is
2922 * being mapped or is referenced by multiple buffers,
2923 * and in those cases we expect races to be rare. At
2924 * worst we will either accelerate reclamation of a
2925 * valid page and violate LRU, or unnecessarily defer
2926 * reclamation of an invalid page.
2928 * The B_NOREUSE flag marks data that is not expected to
2929 * be reused, so accelerate reclamation in that case
2930 * too. Otherwise, maintain LRU.
2932 if (m->valid == 0 || (bp->b_flags & B_NOREUSE) != 0)
2933 vm_page_deactivate_noreuse(m);
2934 else if (m->queue == PQ_ACTIVE)
2935 vm_page_reference(m);
2937 vm_page_deactivate(m);
2944 * Perform page invalidation when a buffer is released. The fully invalid
2945 * pages will be reclaimed later in vfs_vmio_truncate().
2948 vfs_vmio_invalidate(struct buf *bp)
2952 int i, resid, poffset, presid;
2954 if (buf_mapped(bp)) {
2955 BUF_CHECK_MAPPED(bp);
2956 pmap_qremove(trunc_page((vm_offset_t)bp->b_data), bp->b_npages);
2958 BUF_CHECK_UNMAPPED(bp);
2960 * Get the base offset and length of the buffer. Note that
2961 * in the VMIO case if the buffer block size is not
2962 * page-aligned then b_data pointer may not be page-aligned.
2963 * But our b_pages[] array *IS* page aligned.
2965 * block sizes less then DEV_BSIZE (usually 512) are not
2966 * supported due to the page granularity bits (m->valid,
2967 * m->dirty, etc...).
2969 * See man buf(9) for more information
2971 obj = bp->b_bufobj->bo_object;
2972 resid = bp->b_bufsize;
2973 poffset = bp->b_offset & PAGE_MASK;
2974 VM_OBJECT_WLOCK(obj);
2975 for (i = 0; i < bp->b_npages; i++) {
2977 if (m == bogus_page)
2978 panic("vfs_vmio_invalidate: Unexpected bogus page.");
2979 bp->b_pages[i] = NULL;
2981 presid = resid > (PAGE_SIZE - poffset) ?
2982 (PAGE_SIZE - poffset) : resid;
2983 KASSERT(presid >= 0, ("brelse: extra page"));
2984 while (vm_page_xbusied(m)) {
2986 VM_OBJECT_WUNLOCK(obj);
2987 vm_page_busy_sleep(m, "mbncsh", true);
2988 VM_OBJECT_WLOCK(obj);
2990 if (pmap_page_wired_mappings(m) == 0)
2991 vm_page_set_invalid(m, poffset, presid);
2992 vfs_vmio_unwire(bp, m);
2996 VM_OBJECT_WUNLOCK(obj);
3001 * Page-granular truncation of an existing VMIO buffer.
3004 vfs_vmio_truncate(struct buf *bp, int desiredpages)
3010 if (bp->b_npages == desiredpages)
3013 if (buf_mapped(bp)) {
3014 BUF_CHECK_MAPPED(bp);
3015 pmap_qremove((vm_offset_t)trunc_page((vm_offset_t)bp->b_data) +
3016 (desiredpages << PAGE_SHIFT), bp->b_npages - desiredpages);
3018 BUF_CHECK_UNMAPPED(bp);
3021 * The object lock is needed only if we will attempt to free pages.
3023 obj = (bp->b_flags & B_DIRECT) != 0 ? bp->b_bufobj->bo_object : NULL;
3025 VM_OBJECT_WLOCK(obj);
3026 for (i = desiredpages; i < bp->b_npages; i++) {
3028 KASSERT(m != bogus_page, ("allocbuf: bogus page found"));
3029 bp->b_pages[i] = NULL;
3030 vfs_vmio_unwire(bp, m);
3033 VM_OBJECT_WUNLOCK(obj);
3034 bp->b_npages = desiredpages;
3038 * Byte granular extension of VMIO buffers.
3041 vfs_vmio_extend(struct buf *bp, int desiredpages, int size)
3044 * We are growing the buffer, possibly in a
3045 * byte-granular fashion.
3053 * Step 1, bring in the VM pages from the object, allocating
3054 * them if necessary. We must clear B_CACHE if these pages
3055 * are not valid for the range covered by the buffer.
3057 obj = bp->b_bufobj->bo_object;
3058 VM_OBJECT_WLOCK(obj);
3059 if (bp->b_npages < desiredpages) {
3061 * We must allocate system pages since blocking
3062 * here could interfere with paging I/O, no
3063 * matter which process we are.
3065 * Only exclusive busy can be tested here.
3066 * Blocking on shared busy might lead to
3067 * deadlocks once allocbuf() is called after
3068 * pages are vfs_busy_pages().
3070 (void)vm_page_grab_pages(obj,
3071 OFF_TO_IDX(bp->b_offset) + bp->b_npages,
3072 VM_ALLOC_SYSTEM | VM_ALLOC_IGN_SBUSY |
3073 VM_ALLOC_NOBUSY | VM_ALLOC_WIRED,
3074 &bp->b_pages[bp->b_npages], desiredpages - bp->b_npages);
3075 bp->b_npages = desiredpages;
3079 * Step 2. We've loaded the pages into the buffer,
3080 * we have to figure out if we can still have B_CACHE
3081 * set. Note that B_CACHE is set according to the
3082 * byte-granular range ( bcount and size ), not the
3083 * aligned range ( newbsize ).
3085 * The VM test is against m->valid, which is DEV_BSIZE
3086 * aligned. Needless to say, the validity of the data
3087 * needs to also be DEV_BSIZE aligned. Note that this
3088 * fails with NFS if the server or some other client
3089 * extends the file's EOF. If our buffer is resized,
3090 * B_CACHE may remain set! XXX
3092 toff = bp->b_bcount;
3093 tinc = PAGE_SIZE - ((bp->b_offset + toff) & PAGE_MASK);
3094 while ((bp->b_flags & B_CACHE) && toff < size) {
3097 if (tinc > (size - toff))
3099 pi = ((bp->b_offset & PAGE_MASK) + toff) >> PAGE_SHIFT;
3100 m = bp->b_pages[pi];
3101 vfs_buf_test_cache(bp, bp->b_offset, toff, tinc, m);
3105 VM_OBJECT_WUNLOCK(obj);
3108 * Step 3, fixup the KVA pmap.
3113 BUF_CHECK_UNMAPPED(bp);
3117 * Check to see if a block at a particular lbn is available for a clustered
3121 vfs_bio_clcheck(struct vnode *vp, int size, daddr_t lblkno, daddr_t blkno)
3128 /* If the buf isn't in core skip it */
3129 if ((bpa = gbincore(&vp->v_bufobj, lblkno)) == NULL)
3132 /* If the buf is busy we don't want to wait for it */
3133 if (BUF_LOCK(bpa, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0)
3136 /* Only cluster with valid clusterable delayed write buffers */
3137 if ((bpa->b_flags & (B_DELWRI | B_CLUSTEROK | B_INVAL)) !=
3138 (B_DELWRI | B_CLUSTEROK))
3141 if (bpa->b_bufsize != size)
3145 * Check to see if it is in the expected place on disk and that the
3146 * block has been mapped.
3148 if ((bpa->b_blkno != bpa->b_lblkno) && (bpa->b_blkno == blkno))
3158 * Implement clustered async writes for clearing out B_DELWRI buffers.
3159 * This is much better then the old way of writing only one buffer at
3160 * a time. Note that we may not be presented with the buffers in the
3161 * correct order, so we search for the cluster in both directions.
3164 vfs_bio_awrite(struct buf *bp)
3169 daddr_t lblkno = bp->b_lblkno;
3170 struct vnode *vp = bp->b_vp;
3178 gbflags = (bp->b_data == unmapped_buf) ? GB_UNMAPPED : 0;
3180 * right now we support clustered writing only to regular files. If
3181 * we find a clusterable block we could be in the middle of a cluster
3182 * rather then at the beginning.
3184 if ((vp->v_type == VREG) &&
3185 (vp->v_mount != 0) && /* Only on nodes that have the size info */
3186 (bp->b_flags & (B_CLUSTEROK | B_INVAL)) == B_CLUSTEROK) {
3188 size = vp->v_mount->mnt_stat.f_iosize;
3189 maxcl = MAXPHYS / size;
3192 for (i = 1; i < maxcl; i++)
3193 if (vfs_bio_clcheck(vp, size, lblkno + i,
3194 bp->b_blkno + ((i * size) >> DEV_BSHIFT)) == 0)
3197 for (j = 1; i + j <= maxcl && j <= lblkno; j++)
3198 if (vfs_bio_clcheck(vp, size, lblkno - j,
3199 bp->b_blkno - ((j * size) >> DEV_BSHIFT)) == 0)
3205 * this is a possible cluster write
3209 nwritten = cluster_wbuild(vp, size, lblkno - j, ncl,
3215 bp->b_flags |= B_ASYNC;
3217 * default (old) behavior, writing out only one block
3219 * XXX returns b_bufsize instead of b_bcount for nwritten?
3221 nwritten = bp->b_bufsize;
3230 * Allocate KVA for an empty buf header according to gbflags.
3233 getnewbuf_kva(struct buf *bp, int gbflags, int maxsize)
3236 if ((gbflags & (GB_UNMAPPED | GB_KVAALLOC)) != GB_UNMAPPED) {
3238 * In order to keep fragmentation sane we only allocate kva
3239 * in BKVASIZE chunks. XXX with vmem we can do page size.
3241 maxsize = (maxsize + BKVAMASK) & ~BKVAMASK;
3243 if (maxsize != bp->b_kvasize &&
3244 bufkva_alloc(bp, maxsize, gbflags))
3253 * Find and initialize a new buffer header, freeing up existing buffers
3254 * in the bufqueues as necessary. The new buffer is returned locked.
3257 * We have insufficient buffer headers
3258 * We have insufficient buffer space
3259 * buffer_arena is too fragmented ( space reservation fails )
3260 * If we have to flush dirty buffers ( but we try to avoid this )
3262 * The caller is responsible for releasing the reserved bufspace after
3263 * allocbuf() is called.
3266 getnewbuf(struct vnode *vp, int slpflag, int slptimeo, int maxsize, int gbflags)
3268 struct bufdomain *bd;
3270 bool metadata, reserved;
3273 KASSERT((gbflags & (GB_UNMAPPED | GB_KVAALLOC)) != GB_KVAALLOC,
3274 ("GB_KVAALLOC only makes sense with GB_UNMAPPED"));
3275 if (!unmapped_buf_allowed)
3276 gbflags &= ~(GB_UNMAPPED | GB_KVAALLOC);
3278 if (vp == NULL || (vp->v_vflag & (VV_MD | VV_SYSTEM)) != 0 ||
3286 bd = &bdomain[vp->v_bufobj.bo_domain];
3288 counter_u64_add(getnewbufcalls, 1);
3291 if (reserved == false &&
3292 bufspace_reserve(bd, maxsize, metadata) != 0) {
3293 counter_u64_add(getnewbufrestarts, 1);
3297 if ((bp = buf_alloc(bd)) == NULL) {
3298 counter_u64_add(getnewbufrestarts, 1);
3301 if (getnewbuf_kva(bp, gbflags, maxsize) == 0)
3304 } while (buf_recycle(bd, false) == 0);
3307 bufspace_release(bd, maxsize);
3309 bp->b_flags |= B_INVAL;
3312 bufspace_wait(bd, vp, gbflags, slpflag, slptimeo);
3320 * buffer flushing daemon. Buffers are normally flushed by the
3321 * update daemon but if it cannot keep up this process starts to
3322 * take the load in an attempt to prevent getnewbuf() from blocking.
3324 static struct kproc_desc buf_kp = {
3329 SYSINIT(bufdaemon, SI_SUB_KTHREAD_BUF, SI_ORDER_FIRST, kproc_start, &buf_kp);
3332 buf_flush(struct vnode *vp, struct bufdomain *bd, int target)
3336 flushed = flushbufqueues(vp, bd, target, 0);
3339 * Could not find any buffers without rollback
3340 * dependencies, so just write the first one
3341 * in the hopes of eventually making progress.
3343 if (vp != NULL && target > 2)
3345 flushbufqueues(vp, bd, target, 1);
3353 struct bufdomain *bd;
3359 * This process needs to be suspended prior to shutdown sync.
3361 EVENTHANDLER_REGISTER(shutdown_pre_sync, kproc_shutdown, bufdaemonproc,
3365 * Start the buf clean daemons as children threads.
3367 for (i = 0 ; i < buf_domains; i++) {
3370 error = kthread_add((void (*)(void *))bufspace_daemon,
3371 &bdomain[i], curproc, NULL, 0, 0, "bufspacedaemon-%d", i);
3373 panic("error %d spawning bufspace daemon", error);
3377 * This process is allowed to take the buffer cache to the limit
3379 curthread->td_pflags |= TDP_NORUNNINGBUF | TDP_BUFNEED;
3383 mtx_unlock(&bdlock);
3385 kproc_suspend_check(bufdaemonproc);
3388 * Save speedupreq for this pass and reset to capture new
3391 speedupreq = bd_speedupreq;
3395 * Flush each domain sequentially according to its level and
3396 * the speedup request.
3398 for (i = 0; i < buf_domains; i++) {
3401 lodirty = bd->bd_numdirtybuffers / 2;
3403 lodirty = bd->bd_lodirtybuffers;
3404 while (bd->bd_numdirtybuffers > lodirty) {
3405 if (buf_flush(NULL, bd,
3406 bd->bd_numdirtybuffers - lodirty) == 0)
3408 kern_yield(PRI_USER);
3413 * Only clear bd_request if we have reached our low water
3414 * mark. The buf_daemon normally waits 1 second and
3415 * then incrementally flushes any dirty buffers that have
3416 * built up, within reason.
3418 * If we were unable to hit our low water mark and couldn't
3419 * find any flushable buffers, we sleep for a short period
3420 * to avoid endless loops on unlockable buffers.
3423 if (!BIT_EMPTY(BUF_DOMAINS, &bdlodirty)) {
3425 * We reached our low water mark, reset the
3426 * request and sleep until we are needed again.
3427 * The sleep is just so the suspend code works.
3431 * Do an extra wakeup in case dirty threshold
3432 * changed via sysctl and the explicit transition
3433 * out of shortfall was missed.
3436 if (runningbufspace <= lorunningspace)
3438 msleep(&bd_request, &bdlock, PVM, "psleep", hz);
3441 * We couldn't find any flushable dirty buffers but
3442 * still have too many dirty buffers, we
3443 * have to sleep and try again. (rare)
3445 msleep(&bd_request, &bdlock, PVM, "qsleep", hz / 10);
3453 * Try to flush a buffer in the dirty queue. We must be careful to
3454 * free up B_INVAL buffers instead of write them, which NFS is
3455 * particularly sensitive to.
3457 static int flushwithdeps = 0;
3458 SYSCTL_INT(_vfs, OID_AUTO, flushwithdeps, CTLFLAG_RW, &flushwithdeps,
3459 0, "Number of buffers flushed with dependecies that require rollbacks");
3462 flushbufqueues(struct vnode *lvp, struct bufdomain *bd, int target,
3465 struct bufqueue *bq;
3466 struct buf *sentinel;
3476 bq = &bd->bd_dirtyq;
3478 sentinel = malloc(sizeof(struct buf), M_TEMP, M_WAITOK | M_ZERO);
3479 sentinel->b_qindex = QUEUE_SENTINEL;
3481 TAILQ_INSERT_HEAD(&bq->bq_queue, sentinel, b_freelist);
3483 while (flushed != target) {
3486 bp = TAILQ_NEXT(sentinel, b_freelist);
3488 TAILQ_REMOVE(&bq->bq_queue, sentinel, b_freelist);
3489 TAILQ_INSERT_AFTER(&bq->bq_queue, bp, sentinel,
3496 * Skip sentinels inserted by other invocations of the
3497 * flushbufqueues(), taking care to not reorder them.
3499 * Only flush the buffers that belong to the
3500 * vnode locked by the curthread.
3502 if (bp->b_qindex == QUEUE_SENTINEL || (lvp != NULL &&
3507 error = BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL);
3513 * BKGRDINPROG can only be set with the buf and bufobj
3514 * locks both held. We tolerate a race to clear it here.
3516 if ((bp->b_vflags & BV_BKGRDINPROG) != 0 ||
3517 (bp->b_flags & B_DELWRI) == 0) {
3521 if (bp->b_flags & B_INVAL) {
3528 if (!LIST_EMPTY(&bp->b_dep) && buf_countdeps(bp, 0)) {
3529 if (flushdeps == 0) {
3537 * We must hold the lock on a vnode before writing
3538 * one of its buffers. Otherwise we may confuse, or
3539 * in the case of a snapshot vnode, deadlock the
3542 * The lock order here is the reverse of the normal
3543 * of vnode followed by buf lock. This is ok because
3544 * the NOWAIT will prevent deadlock.
3547 if (vn_start_write(vp, &mp, V_NOWAIT) != 0) {
3553 error = vn_lock(vp, LK_EXCLUSIVE | LK_NOWAIT);
3555 ASSERT_VOP_LOCKED(vp, "getbuf");
3557 error = VOP_ISLOCKED(vp) == LK_EXCLUSIVE ? 0 :
3558 vn_lock(vp, LK_TRYUPGRADE);
3561 CTR3(KTR_BUF, "flushbufqueue(%p) vp %p flags %X",
3562 bp, bp->b_vp, bp->b_flags);
3563 if (curproc == bufdaemonproc) {
3568 counter_u64_add(notbufdflushes, 1);
3570 vn_finished_write(mp);
3573 flushwithdeps += hasdeps;
3577 * Sleeping on runningbufspace while holding
3578 * vnode lock leads to deadlock.
3580 if (curproc == bufdaemonproc &&
3581 runningbufspace > hirunningspace)
3582 waitrunningbufspace();
3585 vn_finished_write(mp);
3589 TAILQ_REMOVE(&bq->bq_queue, sentinel, b_freelist);
3591 free(sentinel, M_TEMP);
3596 * Check to see if a block is currently memory resident.
3599 incore(struct bufobj *bo, daddr_t blkno)
3604 bp = gbincore(bo, blkno);
3610 * Returns true if no I/O is needed to access the
3611 * associated VM object. This is like incore except
3612 * it also hunts around in the VM system for the data.
3616 inmem(struct vnode * vp, daddr_t blkno)
3619 vm_offset_t toff, tinc, size;
3623 ASSERT_VOP_LOCKED(vp, "inmem");
3625 if (incore(&vp->v_bufobj, blkno))
3627 if (vp->v_mount == NULL)
3634 if (size > vp->v_mount->mnt_stat.f_iosize)
3635 size = vp->v_mount->mnt_stat.f_iosize;
3636 off = (vm_ooffset_t)blkno * (vm_ooffset_t)vp->v_mount->mnt_stat.f_iosize;
3638 VM_OBJECT_RLOCK(obj);
3639 for (toff = 0; toff < vp->v_mount->mnt_stat.f_iosize; toff += tinc) {
3640 m = vm_page_lookup(obj, OFF_TO_IDX(off + toff));
3644 if (tinc > PAGE_SIZE - ((toff + off) & PAGE_MASK))
3645 tinc = PAGE_SIZE - ((toff + off) & PAGE_MASK);
3646 if (vm_page_is_valid(m,
3647 (vm_offset_t) ((toff + off) & PAGE_MASK), tinc) == 0)
3650 VM_OBJECT_RUNLOCK(obj);
3654 VM_OBJECT_RUNLOCK(obj);
3659 * Set the dirty range for a buffer based on the status of the dirty
3660 * bits in the pages comprising the buffer. The range is limited
3661 * to the size of the buffer.
3663 * Tell the VM system that the pages associated with this buffer
3664 * are clean. This is used for delayed writes where the data is
3665 * going to go to disk eventually without additional VM intevention.
3667 * Note that while we only really need to clean through to b_bcount, we
3668 * just go ahead and clean through to b_bufsize.
3671 vfs_clean_pages_dirty_buf(struct buf *bp)
3673 vm_ooffset_t foff, noff, eoff;
3677 if ((bp->b_flags & B_VMIO) == 0 || bp->b_bufsize == 0)
3680 foff = bp->b_offset;
3681 KASSERT(bp->b_offset != NOOFFSET,
3682 ("vfs_clean_pages_dirty_buf: no buffer offset"));
3684 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object);
3685 vfs_drain_busy_pages(bp);
3686 vfs_setdirty_locked_object(bp);
3687 for (i = 0; i < bp->b_npages; i++) {
3688 noff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK;
3690 if (eoff > bp->b_offset + bp->b_bufsize)
3691 eoff = bp->b_offset + bp->b_bufsize;
3693 vfs_page_set_validclean(bp, foff, m);
3694 /* vm_page_clear_dirty(m, foff & PAGE_MASK, eoff - foff); */
3697 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object);
3701 vfs_setdirty_locked_object(struct buf *bp)
3706 object = bp->b_bufobj->bo_object;
3707 VM_OBJECT_ASSERT_WLOCKED(object);
3710 * We qualify the scan for modified pages on whether the
3711 * object has been flushed yet.
3713 if ((object->flags & OBJ_MIGHTBEDIRTY) != 0) {
3714 vm_offset_t boffset;
3715 vm_offset_t eoffset;
3718 * test the pages to see if they have been modified directly
3719 * by users through the VM system.
3721 for (i = 0; i < bp->b_npages; i++)
3722 vm_page_test_dirty(bp->b_pages[i]);
3725 * Calculate the encompassing dirty range, boffset and eoffset,
3726 * (eoffset - boffset) bytes.
3729 for (i = 0; i < bp->b_npages; i++) {
3730 if (bp->b_pages[i]->dirty)
3733 boffset = (i << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK);
3735 for (i = bp->b_npages - 1; i >= 0; --i) {
3736 if (bp->b_pages[i]->dirty) {
3740 eoffset = ((i + 1) << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK);
3743 * Fit it to the buffer.
3746 if (eoffset > bp->b_bcount)
3747 eoffset = bp->b_bcount;
3750 * If we have a good dirty range, merge with the existing
3754 if (boffset < eoffset) {
3755 if (bp->b_dirtyoff > boffset)
3756 bp->b_dirtyoff = boffset;
3757 if (bp->b_dirtyend < eoffset)
3758 bp->b_dirtyend = eoffset;
3764 * Allocate the KVA mapping for an existing buffer.
3765 * If an unmapped buffer is provided but a mapped buffer is requested, take
3766 * also care to properly setup mappings between pages and KVA.
3769 bp_unmapped_get_kva(struct buf *bp, daddr_t blkno, int size, int gbflags)
3771 int bsize, maxsize, need_mapping, need_kva;
3774 need_mapping = bp->b_data == unmapped_buf &&
3775 (gbflags & GB_UNMAPPED) == 0;
3776 need_kva = bp->b_kvabase == unmapped_buf &&
3777 bp->b_data == unmapped_buf &&
3778 (gbflags & GB_KVAALLOC) != 0;
3779 if (!need_mapping && !need_kva)
3782 BUF_CHECK_UNMAPPED(bp);
3784 if (need_mapping && bp->b_kvabase != unmapped_buf) {
3786 * Buffer is not mapped, but the KVA was already
3787 * reserved at the time of the instantiation. Use the
3794 * Calculate the amount of the address space we would reserve
3795 * if the buffer was mapped.
3797 bsize = vn_isdisk(bp->b_vp, NULL) ? DEV_BSIZE : bp->b_bufobj->bo_bsize;
3798 KASSERT(bsize != 0, ("bsize == 0, check bo->bo_bsize"));
3799 offset = blkno * bsize;
3800 maxsize = size + (offset & PAGE_MASK);
3801 maxsize = imax(maxsize, bsize);
3803 while (bufkva_alloc(bp, maxsize, gbflags) != 0) {
3804 if ((gbflags & GB_NOWAIT_BD) != 0) {
3806 * XXXKIB: defragmentation cannot
3807 * succeed, not sure what else to do.
3809 panic("GB_NOWAIT_BD and GB_UNMAPPED %p", bp);
3811 counter_u64_add(mappingrestarts, 1);
3812 bufspace_wait(bufdomain(bp), bp->b_vp, gbflags, 0, 0);
3816 /* b_offset is handled by bpmap_qenter. */
3817 bp->b_data = bp->b_kvabase;
3818 BUF_CHECK_MAPPED(bp);
3826 * Get a block given a specified block and offset into a file/device.
3827 * The buffers B_DONE bit will be cleared on return, making it almost
3828 * ready for an I/O initiation. B_INVAL may or may not be set on
3829 * return. The caller should clear B_INVAL prior to initiating a
3832 * For a non-VMIO buffer, B_CACHE is set to the opposite of B_INVAL for
3833 * an existing buffer.
3835 * For a VMIO buffer, B_CACHE is modified according to the backing VM.
3836 * If getblk()ing a previously 0-sized invalid buffer, B_CACHE is set
3837 * and then cleared based on the backing VM. If the previous buffer is
3838 * non-0-sized but invalid, B_CACHE will be cleared.
3840 * If getblk() must create a new buffer, the new buffer is returned with
3841 * both B_INVAL and B_CACHE clear unless it is a VMIO buffer, in which
3842 * case it is returned with B_INVAL clear and B_CACHE set based on the
3845 * getblk() also forces a bwrite() for any B_DELWRI buffer whos
3846 * B_CACHE bit is clear.
3848 * What this means, basically, is that the caller should use B_CACHE to
3849 * determine whether the buffer is fully valid or not and should clear
3850 * B_INVAL prior to issuing a read. If the caller intends to validate
3851 * the buffer by loading its data area with something, the caller needs
3852 * to clear B_INVAL. If the caller does this without issuing an I/O,
3853 * the caller should set B_CACHE ( as an optimization ), else the caller
3854 * should issue the I/O and biodone() will set B_CACHE if the I/O was
3855 * a write attempt or if it was a successful read. If the caller
3856 * intends to issue a READ, the caller must clear B_INVAL and BIO_ERROR
3857 * prior to issuing the READ. biodone() will *not* clear B_INVAL.
3860 getblk(struct vnode *vp, daddr_t blkno, int size, int slpflag, int slptimeo,
3865 int bsize, error, maxsize, vmio;
3868 CTR3(KTR_BUF, "getblk(%p, %ld, %d)", vp, (long)blkno, size);
3869 KASSERT((flags & (GB_UNMAPPED | GB_KVAALLOC)) != GB_KVAALLOC,
3870 ("GB_KVAALLOC only makes sense with GB_UNMAPPED"));
3871 ASSERT_VOP_LOCKED(vp, "getblk");
3872 if (size > maxbcachebuf)
3873 panic("getblk: size(%d) > maxbcachebuf(%d)\n", size,
3875 if (!unmapped_buf_allowed)
3876 flags &= ~(GB_UNMAPPED | GB_KVAALLOC);
3881 bp = gbincore(bo, blkno);
3885 * Buffer is in-core. If the buffer is not busy nor managed,
3886 * it must be on a queue.
3888 lockflags = LK_EXCLUSIVE | LK_SLEEPFAIL | LK_INTERLOCK;
3890 if (flags & GB_LOCK_NOWAIT)
3891 lockflags |= LK_NOWAIT;
3893 error = BUF_TIMELOCK(bp, lockflags,
3894 BO_LOCKPTR(bo), "getblk", slpflag, slptimeo);
3897 * If we slept and got the lock we have to restart in case
3898 * the buffer changed identities.
3900 if (error == ENOLCK)
3902 /* We timed out or were interrupted. */
3905 /* If recursed, assume caller knows the rules. */
3906 else if (BUF_LOCKRECURSED(bp))
3910 * The buffer is locked. B_CACHE is cleared if the buffer is
3911 * invalid. Otherwise, for a non-VMIO buffer, B_CACHE is set
3912 * and for a VMIO buffer B_CACHE is adjusted according to the
3915 if (bp->b_flags & B_INVAL)
3916 bp->b_flags &= ~B_CACHE;
3917 else if ((bp->b_flags & (B_VMIO | B_INVAL)) == 0)
3918 bp->b_flags |= B_CACHE;
3919 if (bp->b_flags & B_MANAGED)
3920 MPASS(bp->b_qindex == QUEUE_NONE);
3925 * check for size inconsistencies for non-VMIO case.
3927 if (bp->b_bcount != size) {
3928 if ((bp->b_flags & B_VMIO) == 0 ||
3929 (size > bp->b_kvasize)) {
3930 if (bp->b_flags & B_DELWRI) {
3931 bp->b_flags |= B_NOCACHE;
3934 if (LIST_EMPTY(&bp->b_dep)) {
3935 bp->b_flags |= B_RELBUF;
3938 bp->b_flags |= B_NOCACHE;
3947 * Handle the case of unmapped buffer which should
3948 * become mapped, or the buffer for which KVA
3949 * reservation is requested.
3951 bp_unmapped_get_kva(bp, blkno, size, flags);
3954 * If the size is inconsistent in the VMIO case, we can resize
3955 * the buffer. This might lead to B_CACHE getting set or
3956 * cleared. If the size has not changed, B_CACHE remains
3957 * unchanged from its previous state.
3961 KASSERT(bp->b_offset != NOOFFSET,
3962 ("getblk: no buffer offset"));
3965 * A buffer with B_DELWRI set and B_CACHE clear must
3966 * be committed before we can return the buffer in
3967 * order to prevent the caller from issuing a read
3968 * ( due to B_CACHE not being set ) and overwriting
3971 * Most callers, including NFS and FFS, need this to
3972 * operate properly either because they assume they
3973 * can issue a read if B_CACHE is not set, or because
3974 * ( for example ) an uncached B_DELWRI might loop due
3975 * to softupdates re-dirtying the buffer. In the latter
3976 * case, B_CACHE is set after the first write completes,
3977 * preventing further loops.
3978 * NOTE! b*write() sets B_CACHE. If we cleared B_CACHE
3979 * above while extending the buffer, we cannot allow the
3980 * buffer to remain with B_CACHE set after the write
3981 * completes or it will represent a corrupt state. To
3982 * deal with this we set B_NOCACHE to scrap the buffer
3985 * We might be able to do something fancy, like setting
3986 * B_CACHE in bwrite() except if B_DELWRI is already set,
3987 * so the below call doesn't set B_CACHE, but that gets real
3988 * confusing. This is much easier.
3991 if ((bp->b_flags & (B_CACHE|B_DELWRI)) == B_DELWRI) {
3992 bp->b_flags |= B_NOCACHE;
3996 bp->b_flags &= ~B_DONE;
3999 * Buffer is not in-core, create new buffer. The buffer
4000 * returned by getnewbuf() is locked. Note that the returned
4001 * buffer is also considered valid (not marked B_INVAL).
4005 * If the user does not want us to create the buffer, bail out
4008 if (flags & GB_NOCREAT)
4010 if (bdomain[bo->bo_domain].bd_freebuffers == 0 &&
4011 TD_IS_IDLETHREAD(curthread))
4014 bsize = vn_isdisk(vp, NULL) ? DEV_BSIZE : bo->bo_bsize;
4015 KASSERT(bsize != 0, ("bsize == 0, check bo->bo_bsize"));
4016 offset = blkno * bsize;
4017 vmio = vp->v_object != NULL;
4019 maxsize = size + (offset & PAGE_MASK);
4022 /* Do not allow non-VMIO notmapped buffers. */
4023 flags &= ~(GB_UNMAPPED | GB_KVAALLOC);
4025 maxsize = imax(maxsize, bsize);
4027 bp = getnewbuf(vp, slpflag, slptimeo, maxsize, flags);
4029 if (slpflag || slptimeo)
4032 * XXX This is here until the sleep path is diagnosed
4033 * enough to work under very low memory conditions.
4035 * There's an issue on low memory, 4BSD+non-preempt
4036 * systems (eg MIPS routers with 32MB RAM) where buffer
4037 * exhaustion occurs without sleeping for buffer
4038 * reclaimation. This just sticks in a loop and
4039 * constantly attempts to allocate a buffer, which
4040 * hits exhaustion and tries to wakeup bufdaemon.
4041 * This never happens because we never yield.
4043 * The real solution is to identify and fix these cases
4044 * so we aren't effectively busy-waiting in a loop
4045 * until the reclaimation path has cycles to run.
4047 kern_yield(PRI_USER);
4052 * This code is used to make sure that a buffer is not
4053 * created while the getnewbuf routine is blocked.
4054 * This can be a problem whether the vnode is locked or not.
4055 * If the buffer is created out from under us, we have to
4056 * throw away the one we just created.
4058 * Note: this must occur before we associate the buffer
4059 * with the vp especially considering limitations in
4060 * the splay tree implementation when dealing with duplicate
4064 if (gbincore(bo, blkno)) {
4066 bp->b_flags |= B_INVAL;
4067 bufspace_release(bufdomain(bp), maxsize);
4073 * Insert the buffer into the hash, so that it can
4074 * be found by incore.
4076 bp->b_blkno = bp->b_lblkno = blkno;
4077 bp->b_offset = offset;
4082 * set B_VMIO bit. allocbuf() the buffer bigger. Since the
4083 * buffer size starts out as 0, B_CACHE will be set by
4084 * allocbuf() for the VMIO case prior to it testing the
4085 * backing store for validity.
4089 bp->b_flags |= B_VMIO;
4090 KASSERT(vp->v_object == bp->b_bufobj->bo_object,
4091 ("ARGH! different b_bufobj->bo_object %p %p %p\n",
4092 bp, vp->v_object, bp->b_bufobj->bo_object));
4094 bp->b_flags &= ~B_VMIO;
4095 KASSERT(bp->b_bufobj->bo_object == NULL,
4096 ("ARGH! has b_bufobj->bo_object %p %p\n",
4097 bp, bp->b_bufobj->bo_object));
4098 BUF_CHECK_MAPPED(bp);
4102 bufspace_release(bufdomain(bp), maxsize);
4103 bp->b_flags &= ~B_DONE;
4105 CTR4(KTR_BUF, "getblk(%p, %ld, %d) = %p", vp, (long)blkno, size, bp);
4106 BUF_ASSERT_HELD(bp);
4108 buf_track(bp, __func__);
4109 KASSERT(bp->b_bufobj == bo,
4110 ("bp %p wrong b_bufobj %p should be %p", bp, bp->b_bufobj, bo));
4115 * Get an empty, disassociated buffer of given size. The buffer is initially
4119 geteblk(int size, int flags)
4124 maxsize = (size + BKVAMASK) & ~BKVAMASK;
4125 while ((bp = getnewbuf(NULL, 0, 0, maxsize, flags)) == NULL) {
4126 if ((flags & GB_NOWAIT_BD) &&
4127 (curthread->td_pflags & TDP_BUFNEED) != 0)
4131 bufspace_release(bufdomain(bp), maxsize);
4132 bp->b_flags |= B_INVAL; /* b_dep cleared by getnewbuf() */
4133 BUF_ASSERT_HELD(bp);
4138 * Truncate the backing store for a non-vmio buffer.
4141 vfs_nonvmio_truncate(struct buf *bp, int newbsize)
4144 if (bp->b_flags & B_MALLOC) {
4146 * malloced buffers are not shrunk
4148 if (newbsize == 0) {
4149 bufmallocadjust(bp, 0);
4150 free(bp->b_data, M_BIOBUF);
4151 bp->b_data = bp->b_kvabase;
4152 bp->b_flags &= ~B_MALLOC;
4156 vm_hold_free_pages(bp, newbsize);
4157 bufspace_adjust(bp, newbsize);
4161 * Extend the backing for a non-VMIO buffer.
4164 vfs_nonvmio_extend(struct buf *bp, int newbsize)
4170 * We only use malloced memory on the first allocation.
4171 * and revert to page-allocated memory when the buffer
4174 * There is a potential smp race here that could lead
4175 * to bufmallocspace slightly passing the max. It
4176 * is probably extremely rare and not worth worrying
4179 if (bp->b_bufsize == 0 && newbsize <= PAGE_SIZE/2 &&
4180 bufmallocspace < maxbufmallocspace) {
4181 bp->b_data = malloc(newbsize, M_BIOBUF, M_WAITOK);
4182 bp->b_flags |= B_MALLOC;
4183 bufmallocadjust(bp, newbsize);
4188 * If the buffer is growing on its other-than-first
4189 * allocation then we revert to the page-allocation
4194 if (bp->b_flags & B_MALLOC) {
4195 origbuf = bp->b_data;
4196 origbufsize = bp->b_bufsize;
4197 bp->b_data = bp->b_kvabase;
4198 bufmallocadjust(bp, 0);
4199 bp->b_flags &= ~B_MALLOC;
4200 newbsize = round_page(newbsize);
4202 vm_hold_load_pages(bp, (vm_offset_t) bp->b_data + bp->b_bufsize,
4203 (vm_offset_t) bp->b_data + newbsize);
4204 if (origbuf != NULL) {
4205 bcopy(origbuf, bp->b_data, origbufsize);
4206 free(origbuf, M_BIOBUF);
4208 bufspace_adjust(bp, newbsize);
4212 * This code constitutes the buffer memory from either anonymous system
4213 * memory (in the case of non-VMIO operations) or from an associated
4214 * VM object (in the case of VMIO operations). This code is able to
4215 * resize a buffer up or down.
4217 * Note that this code is tricky, and has many complications to resolve
4218 * deadlock or inconsistent data situations. Tread lightly!!!
4219 * There are B_CACHE and B_DELWRI interactions that must be dealt with by
4220 * the caller. Calling this code willy nilly can result in the loss of data.
4222 * allocbuf() only adjusts B_CACHE for VMIO buffers. getblk() deals with
4223 * B_CACHE for the non-VMIO case.
4226 allocbuf(struct buf *bp, int size)
4230 BUF_ASSERT_HELD(bp);
4232 if (bp->b_bcount == size)
4235 if (bp->b_kvasize != 0 && bp->b_kvasize < size)
4236 panic("allocbuf: buffer too small");
4238 newbsize = roundup2(size, DEV_BSIZE);
4239 if ((bp->b_flags & B_VMIO) == 0) {
4240 if ((bp->b_flags & B_MALLOC) == 0)
4241 newbsize = round_page(newbsize);
4243 * Just get anonymous memory from the kernel. Don't
4244 * mess with B_CACHE.
4246 if (newbsize < bp->b_bufsize)
4247 vfs_nonvmio_truncate(bp, newbsize);
4248 else if (newbsize > bp->b_bufsize)
4249 vfs_nonvmio_extend(bp, newbsize);
4253 desiredpages = (size == 0) ? 0 :
4254 num_pages((bp->b_offset & PAGE_MASK) + newbsize);
4256 if (bp->b_flags & B_MALLOC)
4257 panic("allocbuf: VMIO buffer can't be malloced");
4259 * Set B_CACHE initially if buffer is 0 length or will become
4262 if (size == 0 || bp->b_bufsize == 0)
4263 bp->b_flags |= B_CACHE;
4265 if (newbsize < bp->b_bufsize)
4266 vfs_vmio_truncate(bp, desiredpages);
4267 /* XXX This looks as if it should be newbsize > b_bufsize */
4268 else if (size > bp->b_bcount)
4269 vfs_vmio_extend(bp, desiredpages, size);
4270 bufspace_adjust(bp, newbsize);
4272 bp->b_bcount = size; /* requested buffer size. */
4276 extern int inflight_transient_maps;
4279 biodone(struct bio *bp)
4282 void (*done)(struct bio *);
4283 vm_offset_t start, end;
4285 biotrack(bp, __func__);
4286 if ((bp->bio_flags & BIO_TRANSIENT_MAPPING) != 0) {
4287 bp->bio_flags &= ~BIO_TRANSIENT_MAPPING;
4288 bp->bio_flags |= BIO_UNMAPPED;
4289 start = trunc_page((vm_offset_t)bp->bio_data);
4290 end = round_page((vm_offset_t)bp->bio_data + bp->bio_length);
4291 bp->bio_data = unmapped_buf;
4292 pmap_qremove(start, atop(end - start));
4293 vmem_free(transient_arena, start, end - start);
4294 atomic_add_int(&inflight_transient_maps, -1);
4296 done = bp->bio_done;
4298 mtxp = mtx_pool_find(mtxpool_sleep, bp);
4300 bp->bio_flags |= BIO_DONE;
4308 * Wait for a BIO to finish.
4311 biowait(struct bio *bp, const char *wchan)
4315 mtxp = mtx_pool_find(mtxpool_sleep, bp);
4317 while ((bp->bio_flags & BIO_DONE) == 0)
4318 msleep(bp, mtxp, PRIBIO, wchan, 0);
4320 if (bp->bio_error != 0)
4321 return (bp->bio_error);
4322 if (!(bp->bio_flags & BIO_ERROR))
4328 biofinish(struct bio *bp, struct devstat *stat, int error)
4332 bp->bio_error = error;
4333 bp->bio_flags |= BIO_ERROR;
4336 devstat_end_transaction_bio(stat, bp);
4340 #if defined(BUF_TRACKING) || defined(FULL_BUF_TRACKING)
4342 biotrack_buf(struct bio *bp, const char *location)
4345 buf_track(bp->bio_track_bp, location);
4352 * Wait for buffer I/O completion, returning error status. The buffer
4353 * is left locked and B_DONE on return. B_EINTR is converted into an EINTR
4354 * error and cleared.
4357 bufwait(struct buf *bp)
4359 if (bp->b_iocmd == BIO_READ)
4360 bwait(bp, PRIBIO, "biord");
4362 bwait(bp, PRIBIO, "biowr");
4363 if (bp->b_flags & B_EINTR) {
4364 bp->b_flags &= ~B_EINTR;
4367 if (bp->b_ioflags & BIO_ERROR) {
4368 return (bp->b_error ? bp->b_error : EIO);
4377 * Finish I/O on a buffer, optionally calling a completion function.
4378 * This is usually called from an interrupt so process blocking is
4381 * biodone is also responsible for setting B_CACHE in a B_VMIO bp.
4382 * In a non-VMIO bp, B_CACHE will be set on the next getblk()
4383 * assuming B_INVAL is clear.
4385 * For the VMIO case, we set B_CACHE if the op was a read and no
4386 * read error occurred, or if the op was a write. B_CACHE is never
4387 * set if the buffer is invalid or otherwise uncacheable.
4389 * biodone does not mess with B_INVAL, allowing the I/O routine or the
4390 * initiator to leave B_INVAL set to brelse the buffer out of existence
4391 * in the biodone routine.
4394 bufdone(struct buf *bp)
4396 struct bufobj *dropobj;
4397 void (*biodone)(struct buf *);
4399 buf_track(bp, __func__);
4400 CTR3(KTR_BUF, "bufdone(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
4403 KASSERT(!(bp->b_flags & B_DONE), ("biodone: bp %p already done", bp));
4404 BUF_ASSERT_HELD(bp);
4406 runningbufwakeup(bp);
4407 if (bp->b_iocmd == BIO_WRITE)
4408 dropobj = bp->b_bufobj;
4409 /* call optional completion function if requested */
4410 if (bp->b_iodone != NULL) {
4411 biodone = bp->b_iodone;
4412 bp->b_iodone = NULL;
4415 bufobj_wdrop(dropobj);
4418 if (bp->b_flags & B_VMIO) {
4420 * Set B_CACHE if the op was a normal read and no error
4421 * occurred. B_CACHE is set for writes in the b*write()
4424 if (bp->b_iocmd == BIO_READ &&
4425 !(bp->b_flags & (B_INVAL|B_NOCACHE)) &&
4426 !(bp->b_ioflags & BIO_ERROR))
4427 bp->b_flags |= B_CACHE;
4428 vfs_vmio_iodone(bp);
4430 if (!LIST_EMPTY(&bp->b_dep))
4432 if ((bp->b_flags & B_CKHASH) != 0) {
4433 KASSERT(bp->b_iocmd == BIO_READ,
4434 ("bufdone: b_iocmd %d not BIO_READ", bp->b_iocmd));
4435 KASSERT(buf_mapped(bp), ("bufdone: bp %p not mapped", bp));
4436 (*bp->b_ckhashcalc)(bp);
4439 * For asynchronous completions, release the buffer now. The brelse
4440 * will do a wakeup there if necessary - so no need to do a wakeup
4441 * here in the async case. The sync case always needs to do a wakeup.
4443 if (bp->b_flags & B_ASYNC) {
4444 if ((bp->b_flags & (B_NOCACHE | B_INVAL | B_RELBUF)) ||
4445 (bp->b_ioflags & BIO_ERROR))
4452 bufobj_wdrop(dropobj);
4456 * This routine is called in lieu of iodone in the case of
4457 * incomplete I/O. This keeps the busy status for pages
4461 vfs_unbusy_pages(struct buf *bp)
4467 runningbufwakeup(bp);
4468 if (!(bp->b_flags & B_VMIO))
4471 obj = bp->b_bufobj->bo_object;
4472 VM_OBJECT_WLOCK(obj);
4473 for (i = 0; i < bp->b_npages; i++) {
4475 if (m == bogus_page) {
4476 m = vm_page_lookup(obj, OFF_TO_IDX(bp->b_offset) + i);
4478 panic("vfs_unbusy_pages: page missing\n");
4480 if (buf_mapped(bp)) {
4481 BUF_CHECK_MAPPED(bp);
4482 pmap_qenter(trunc_page((vm_offset_t)bp->b_data),
4483 bp->b_pages, bp->b_npages);
4485 BUF_CHECK_UNMAPPED(bp);
4489 vm_object_pip_wakeupn(obj, bp->b_npages);
4490 VM_OBJECT_WUNLOCK(obj);
4494 * vfs_page_set_valid:
4496 * Set the valid bits in a page based on the supplied offset. The
4497 * range is restricted to the buffer's size.
4499 * This routine is typically called after a read completes.
4502 vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, vm_page_t m)
4507 * Compute the end offset, eoff, such that [off, eoff) does not span a
4508 * page boundary and eoff is not greater than the end of the buffer.
4509 * The end of the buffer, in this case, is our file EOF, not the
4510 * allocation size of the buffer.
4512 eoff = (off + PAGE_SIZE) & ~(vm_ooffset_t)PAGE_MASK;
4513 if (eoff > bp->b_offset + bp->b_bcount)
4514 eoff = bp->b_offset + bp->b_bcount;
4517 * Set valid range. This is typically the entire buffer and thus the
4521 vm_page_set_valid_range(m, off & PAGE_MASK, eoff - off);
4525 * vfs_page_set_validclean:
4527 * Set the valid bits and clear the dirty bits in a page based on the
4528 * supplied offset. The range is restricted to the buffer's size.
4531 vfs_page_set_validclean(struct buf *bp, vm_ooffset_t off, vm_page_t m)
4533 vm_ooffset_t soff, eoff;
4536 * Start and end offsets in buffer. eoff - soff may not cross a
4537 * page boundary or cross the end of the buffer. The end of the
4538 * buffer, in this case, is our file EOF, not the allocation size
4542 eoff = (off + PAGE_SIZE) & ~(off_t)PAGE_MASK;
4543 if (eoff > bp->b_offset + bp->b_bcount)
4544 eoff = bp->b_offset + bp->b_bcount;
4547 * Set valid range. This is typically the entire buffer and thus the
4551 vm_page_set_validclean(
4553 (vm_offset_t) (soff & PAGE_MASK),
4554 (vm_offset_t) (eoff - soff)
4560 * Ensure that all buffer pages are not exclusive busied. If any page is
4561 * exclusive busy, drain it.
4564 vfs_drain_busy_pages(struct buf *bp)
4569 VM_OBJECT_ASSERT_WLOCKED(bp->b_bufobj->bo_object);
4571 for (i = 0; i < bp->b_npages; i++) {
4573 if (vm_page_xbusied(m)) {
4574 for (; last_busied < i; last_busied++)
4575 vm_page_sbusy(bp->b_pages[last_busied]);
4576 while (vm_page_xbusied(m)) {
4578 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object);
4579 vm_page_busy_sleep(m, "vbpage", true);
4580 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object);
4584 for (i = 0; i < last_busied; i++)
4585 vm_page_sunbusy(bp->b_pages[i]);
4589 * This routine is called before a device strategy routine.
4590 * It is used to tell the VM system that paging I/O is in
4591 * progress, and treat the pages associated with the buffer
4592 * almost as being exclusive busy. Also the object paging_in_progress
4593 * flag is handled to make sure that the object doesn't become
4596 * Since I/O has not been initiated yet, certain buffer flags
4597 * such as BIO_ERROR or B_INVAL may be in an inconsistent state
4598 * and should be ignored.
4601 vfs_busy_pages(struct buf *bp, int clear_modify)
4609 if (!(bp->b_flags & B_VMIO))
4612 obj = bp->b_bufobj->bo_object;
4613 foff = bp->b_offset;
4614 KASSERT(bp->b_offset != NOOFFSET,
4615 ("vfs_busy_pages: no buffer offset"));
4616 VM_OBJECT_WLOCK(obj);
4617 vfs_drain_busy_pages(bp);
4618 if (bp->b_bufsize != 0)
4619 vfs_setdirty_locked_object(bp);
4621 for (i = 0; i < bp->b_npages; i++) {
4624 if ((bp->b_flags & B_CLUSTER) == 0) {
4625 vm_object_pip_add(obj, 1);
4629 * When readying a buffer for a read ( i.e
4630 * clear_modify == 0 ), it is important to do
4631 * bogus_page replacement for valid pages in
4632 * partially instantiated buffers. Partially
4633 * instantiated buffers can, in turn, occur when
4634 * reconstituting a buffer from its VM backing store
4635 * base. We only have to do this if B_CACHE is
4636 * clear ( which causes the I/O to occur in the
4637 * first place ). The replacement prevents the read
4638 * I/O from overwriting potentially dirty VM-backed
4639 * pages. XXX bogus page replacement is, uh, bogus.
4640 * It may not work properly with small-block devices.
4641 * We need to find a better way.
4644 pmap_remove_write(m);
4645 vfs_page_set_validclean(bp, foff, m);
4646 } else if (m->valid == VM_PAGE_BITS_ALL &&
4647 (bp->b_flags & B_CACHE) == 0) {
4648 bp->b_pages[i] = bogus_page;
4651 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK;
4653 VM_OBJECT_WUNLOCK(obj);
4654 if (bogus && buf_mapped(bp)) {
4655 BUF_CHECK_MAPPED(bp);
4656 pmap_qenter(trunc_page((vm_offset_t)bp->b_data),
4657 bp->b_pages, bp->b_npages);
4662 * vfs_bio_set_valid:
4664 * Set the range within the buffer to valid. The range is
4665 * relative to the beginning of the buffer, b_offset. Note that
4666 * b_offset itself may be offset from the beginning of the first
4670 vfs_bio_set_valid(struct buf *bp, int base, int size)
4675 if (!(bp->b_flags & B_VMIO))
4679 * Fixup base to be relative to beginning of first page.
4680 * Set initial n to be the maximum number of bytes in the
4681 * first page that can be validated.
4683 base += (bp->b_offset & PAGE_MASK);
4684 n = PAGE_SIZE - (base & PAGE_MASK);
4686 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object);
4687 for (i = base / PAGE_SIZE; size > 0 && i < bp->b_npages; ++i) {
4691 vm_page_set_valid_range(m, base & PAGE_MASK, n);
4696 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object);
4702 * If the specified buffer is a non-VMIO buffer, clear the entire
4703 * buffer. If the specified buffer is a VMIO buffer, clear and
4704 * validate only the previously invalid portions of the buffer.
4705 * This routine essentially fakes an I/O, so we need to clear
4706 * BIO_ERROR and B_INVAL.
4708 * Note that while we only theoretically need to clear through b_bcount,
4709 * we go ahead and clear through b_bufsize.
4712 vfs_bio_clrbuf(struct buf *bp)
4714 int i, j, mask, sa, ea, slide;
4716 if ((bp->b_flags & (B_VMIO | B_MALLOC)) != B_VMIO) {
4720 bp->b_flags &= ~B_INVAL;
4721 bp->b_ioflags &= ~BIO_ERROR;
4722 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object);
4723 if ((bp->b_npages == 1) && (bp->b_bufsize < PAGE_SIZE) &&
4724 (bp->b_offset & PAGE_MASK) == 0) {
4725 if (bp->b_pages[0] == bogus_page)
4727 mask = (1 << (bp->b_bufsize / DEV_BSIZE)) - 1;
4728 VM_OBJECT_ASSERT_WLOCKED(bp->b_pages[0]->object);
4729 if ((bp->b_pages[0]->valid & mask) == mask)
4731 if ((bp->b_pages[0]->valid & mask) == 0) {
4732 pmap_zero_page_area(bp->b_pages[0], 0, bp->b_bufsize);
4733 bp->b_pages[0]->valid |= mask;
4737 sa = bp->b_offset & PAGE_MASK;
4739 for (i = 0; i < bp->b_npages; i++, sa = 0) {
4740 slide = imin(slide + PAGE_SIZE, bp->b_offset + bp->b_bufsize);
4741 ea = slide & PAGE_MASK;
4744 if (bp->b_pages[i] == bogus_page)
4747 mask = ((1 << ((ea - sa) / DEV_BSIZE)) - 1) << j;
4748 VM_OBJECT_ASSERT_WLOCKED(bp->b_pages[i]->object);
4749 if ((bp->b_pages[i]->valid & mask) == mask)
4751 if ((bp->b_pages[i]->valid & mask) == 0)
4752 pmap_zero_page_area(bp->b_pages[i], sa, ea - sa);
4754 for (; sa < ea; sa += DEV_BSIZE, j++) {
4755 if ((bp->b_pages[i]->valid & (1 << j)) == 0) {
4756 pmap_zero_page_area(bp->b_pages[i],
4761 bp->b_pages[i]->valid |= mask;
4764 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object);
4769 vfs_bio_bzero_buf(struct buf *bp, int base, int size)
4774 if (buf_mapped(bp)) {
4775 BUF_CHECK_MAPPED(bp);
4776 bzero(bp->b_data + base, size);
4778 BUF_CHECK_UNMAPPED(bp);
4779 n = PAGE_SIZE - (base & PAGE_MASK);
4780 for (i = base / PAGE_SIZE; size > 0 && i < bp->b_npages; ++i) {
4784 pmap_zero_page_area(m, base & PAGE_MASK, n);
4793 * Update buffer flags based on I/O request parameters, optionally releasing the
4794 * buffer. If it's VMIO or direct I/O, the buffer pages are released to the VM,
4795 * where they may be placed on a page queue (VMIO) or freed immediately (direct
4796 * I/O). Otherwise the buffer is released to the cache.
4799 b_io_dismiss(struct buf *bp, int ioflag, bool release)
4802 KASSERT((ioflag & IO_NOREUSE) == 0 || (ioflag & IO_VMIO) != 0,
4803 ("buf %p non-VMIO noreuse", bp));
4805 if ((ioflag & IO_DIRECT) != 0)
4806 bp->b_flags |= B_DIRECT;
4807 if ((ioflag & (IO_VMIO | IO_DIRECT)) != 0 && LIST_EMPTY(&bp->b_dep)) {
4808 bp->b_flags |= B_RELBUF;
4809 if ((ioflag & IO_NOREUSE) != 0)
4810 bp->b_flags |= B_NOREUSE;
4818 vfs_bio_brelse(struct buf *bp, int ioflag)
4821 b_io_dismiss(bp, ioflag, true);
4825 vfs_bio_set_flags(struct buf *bp, int ioflag)
4828 b_io_dismiss(bp, ioflag, false);
4832 * vm_hold_load_pages and vm_hold_free_pages get pages into
4833 * a buffers address space. The pages are anonymous and are
4834 * not associated with a file object.
4837 vm_hold_load_pages(struct buf *bp, vm_offset_t from, vm_offset_t to)
4843 BUF_CHECK_MAPPED(bp);
4845 to = round_page(to);
4846 from = round_page(from);
4847 index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT;
4849 for (pg = from; pg < to; pg += PAGE_SIZE, index++) {
4851 * note: must allocate system pages since blocking here
4852 * could interfere with paging I/O, no matter which
4855 p = vm_page_alloc(NULL, 0, VM_ALLOC_SYSTEM | VM_ALLOC_NOOBJ |
4856 VM_ALLOC_WIRED | VM_ALLOC_COUNT((to - pg) >> PAGE_SHIFT) |
4858 pmap_qenter(pg, &p, 1);
4859 bp->b_pages[index] = p;
4861 bp->b_npages = index;
4864 /* Return pages associated with this buf to the vm system */
4866 vm_hold_free_pages(struct buf *bp, int newbsize)
4870 int index, newnpages;
4872 BUF_CHECK_MAPPED(bp);
4874 from = round_page((vm_offset_t)bp->b_data + newbsize);
4875 newnpages = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT;
4876 if (bp->b_npages > newnpages)
4877 pmap_qremove(from, bp->b_npages - newnpages);
4878 for (index = newnpages; index < bp->b_npages; index++) {
4879 p = bp->b_pages[index];
4880 bp->b_pages[index] = NULL;
4884 vm_wire_sub(bp->b_npages - newnpages);
4885 bp->b_npages = newnpages;
4889 * Map an IO request into kernel virtual address space.
4891 * All requests are (re)mapped into kernel VA space.
4892 * Notice that we use b_bufsize for the size of the buffer
4893 * to be mapped. b_bcount might be modified by the driver.
4895 * Note that even if the caller determines that the address space should
4896 * be valid, a race or a smaller-file mapped into a larger space may
4897 * actually cause vmapbuf() to fail, so all callers of vmapbuf() MUST
4898 * check the return value.
4900 * This function only works with pager buffers.
4903 vmapbuf(struct buf *bp, int mapbuf)
4908 if (bp->b_bufsize < 0)
4910 prot = VM_PROT_READ;
4911 if (bp->b_iocmd == BIO_READ)
4912 prot |= VM_PROT_WRITE; /* Less backwards than it looks */
4913 if ((pidx = vm_fault_quick_hold_pages(&curproc->p_vmspace->vm_map,
4914 (vm_offset_t)bp->b_data, bp->b_bufsize, prot, bp->b_pages,
4915 btoc(MAXPHYS))) < 0)
4917 bp->b_npages = pidx;
4918 bp->b_offset = ((vm_offset_t)bp->b_data) & PAGE_MASK;
4919 if (mapbuf || !unmapped_buf_allowed) {
4920 pmap_qenter((vm_offset_t)bp->b_kvabase, bp->b_pages, pidx);
4921 bp->b_data = bp->b_kvabase + bp->b_offset;
4923 bp->b_data = unmapped_buf;
4928 * Free the io map PTEs associated with this IO operation.
4929 * We also invalidate the TLB entries and restore the original b_addr.
4931 * This function only works with pager buffers.
4934 vunmapbuf(struct buf *bp)
4938 npages = bp->b_npages;
4940 pmap_qremove(trunc_page((vm_offset_t)bp->b_data), npages);
4941 vm_page_unhold_pages(bp->b_pages, npages);
4943 bp->b_data = unmapped_buf;
4947 bdone(struct buf *bp)
4951 mtxp = mtx_pool_find(mtxpool_sleep, bp);
4953 bp->b_flags |= B_DONE;
4959 bwait(struct buf *bp, u_char pri, const char *wchan)
4963 mtxp = mtx_pool_find(mtxpool_sleep, bp);
4965 while ((bp->b_flags & B_DONE) == 0)
4966 msleep(bp, mtxp, pri, wchan, 0);
4971 bufsync(struct bufobj *bo, int waitfor)
4974 return (VOP_FSYNC(bo2vnode(bo), waitfor, curthread));
4978 bufstrategy(struct bufobj *bo, struct buf *bp)
4984 KASSERT(vp == bo->bo_private, ("Inconsistent vnode bufstrategy"));
4985 KASSERT(vp->v_type != VCHR && vp->v_type != VBLK,
4986 ("Wrong vnode in bufstrategy(bp=%p, vp=%p)", bp, vp));
4987 i = VOP_STRATEGY(vp, bp);
4988 KASSERT(i == 0, ("VOP_STRATEGY failed bp=%p vp=%p", bp, bp->b_vp));
4992 * Initialize a struct bufobj before use. Memory is assumed zero filled.
4995 bufobj_init(struct bufobj *bo, void *private)
4997 static volatile int bufobj_cleanq;
5000 atomic_fetchadd_int(&bufobj_cleanq, 1) % buf_domains;
5001 rw_init(BO_LOCKPTR(bo), "bufobj interlock");
5002 bo->bo_private = private;
5003 TAILQ_INIT(&bo->bo_clean.bv_hd);
5004 TAILQ_INIT(&bo->bo_dirty.bv_hd);
5008 bufobj_wrefl(struct bufobj *bo)
5011 KASSERT(bo != NULL, ("NULL bo in bufobj_wref"));
5012 ASSERT_BO_WLOCKED(bo);
5017 bufobj_wref(struct bufobj *bo)
5020 KASSERT(bo != NULL, ("NULL bo in bufobj_wref"));
5027 bufobj_wdrop(struct bufobj *bo)
5030 KASSERT(bo != NULL, ("NULL bo in bufobj_wdrop"));
5032 KASSERT(bo->bo_numoutput > 0, ("bufobj_wdrop non-positive count"));
5033 if ((--bo->bo_numoutput == 0) && (bo->bo_flag & BO_WWAIT)) {
5034 bo->bo_flag &= ~BO_WWAIT;
5035 wakeup(&bo->bo_numoutput);
5041 bufobj_wwait(struct bufobj *bo, int slpflag, int timeo)
5045 KASSERT(bo != NULL, ("NULL bo in bufobj_wwait"));
5046 ASSERT_BO_WLOCKED(bo);
5048 while (bo->bo_numoutput) {
5049 bo->bo_flag |= BO_WWAIT;
5050 error = msleep(&bo->bo_numoutput, BO_LOCKPTR(bo),
5051 slpflag | (PRIBIO + 1), "bo_wwait", timeo);
5059 * Set bio_data or bio_ma for struct bio from the struct buf.
5062 bdata2bio(struct buf *bp, struct bio *bip)
5065 if (!buf_mapped(bp)) {
5066 KASSERT(unmapped_buf_allowed, ("unmapped"));
5067 bip->bio_ma = bp->b_pages;
5068 bip->bio_ma_n = bp->b_npages;
5069 bip->bio_data = unmapped_buf;
5070 bip->bio_ma_offset = (vm_offset_t)bp->b_offset & PAGE_MASK;
5071 bip->bio_flags |= BIO_UNMAPPED;
5072 KASSERT(round_page(bip->bio_ma_offset + bip->bio_length) /
5073 PAGE_SIZE == bp->b_npages,
5074 ("Buffer %p too short: %d %lld %d", bp, bip->bio_ma_offset,
5075 (long long)bip->bio_length, bip->bio_ma_n));
5077 bip->bio_data = bp->b_data;
5083 * The MIPS pmap code currently doesn't handle aliased pages.
5084 * The VIPT caches may not handle page aliasing themselves, leading
5085 * to data corruption.
5087 * As such, this code makes a system extremely unhappy if said
5088 * system doesn't support unaliasing the above situation in hardware.
5089 * Some "recent" systems (eg some mips24k/mips74k cores) don't enable
5090 * this feature at build time, so it has to be handled in software.
5092 * Once the MIPS pmap/cache code grows to support this function on
5093 * earlier chips, it should be flipped back off.
5096 static int buf_pager_relbuf = 1;
5098 static int buf_pager_relbuf = 0;
5100 SYSCTL_INT(_vfs, OID_AUTO, buf_pager_relbuf, CTLFLAG_RWTUN,
5101 &buf_pager_relbuf, 0,
5102 "Make buffer pager release buffers after reading");
5105 * The buffer pager. It uses buffer reads to validate pages.
5107 * In contrast to the generic local pager from vm/vnode_pager.c, this
5108 * pager correctly and easily handles volumes where the underlying
5109 * device block size is greater than the machine page size. The
5110 * buffer cache transparently extends the requested page run to be
5111 * aligned at the block boundary, and does the necessary bogus page
5112 * replacements in the addends to avoid obliterating already valid
5115 * The only non-trivial issue is that the exclusive busy state for
5116 * pages, which is assumed by the vm_pager_getpages() interface, is
5117 * incompatible with the VMIO buffer cache's desire to share-busy the
5118 * pages. This function performs a trivial downgrade of the pages'
5119 * state before reading buffers, and a less trivial upgrade from the
5120 * shared-busy to excl-busy state after the read.
5123 vfs_bio_getpages(struct vnode *vp, vm_page_t *ma, int count,
5124 int *rbehind, int *rahead, vbg_get_lblkno_t get_lblkno,
5125 vbg_get_blksize_t get_blksize)
5132 vm_ooffset_t la, lb, poff, poffe;
5134 int bo_bs, br_flags, error, i, pgsin, pgsin_a, pgsin_b;
5137 object = vp->v_object;
5140 la = IDX_TO_OFF(ma[count - 1]->pindex);
5141 if (la >= object->un_pager.vnp.vnp_size)
5142 return (VM_PAGER_BAD);
5145 * Change the meaning of la from where the last requested page starts
5146 * to where it ends, because that's the end of the requested region
5147 * and the start of the potential read-ahead region.
5150 lpart = la > object->un_pager.vnp.vnp_size;
5151 bo_bs = get_blksize(vp, get_lblkno(vp, IDX_TO_OFF(ma[0]->pindex)));
5154 * Calculate read-ahead, behind and total pages.
5157 lb = IDX_TO_OFF(ma[0]->pindex);
5158 pgsin_b = OFF_TO_IDX(lb - rounddown2(lb, bo_bs));
5160 if (rbehind != NULL)
5162 pgsin_a = OFF_TO_IDX(roundup2(la, bo_bs) - la);
5163 if (la + IDX_TO_OFF(pgsin_a) >= object->un_pager.vnp.vnp_size)
5164 pgsin_a = OFF_TO_IDX(roundup2(object->un_pager.vnp.vnp_size,
5169 VM_CNT_INC(v_vnodein);
5170 VM_CNT_ADD(v_vnodepgsin, pgsin);
5172 br_flags = (mp != NULL && (mp->mnt_kern_flag & MNTK_UNMAPPED_BUFS)
5173 != 0) ? GB_UNMAPPED : 0;
5174 VM_OBJECT_WLOCK(object);
5176 for (i = 0; i < count; i++)
5177 vm_page_busy_downgrade(ma[i]);
5178 VM_OBJECT_WUNLOCK(object);
5181 for (i = 0; i < count; i++) {
5185 * Pages are shared busy and the object lock is not
5186 * owned, which together allow for the pages'
5187 * invalidation. The racy test for validity avoids
5188 * useless creation of the buffer for the most typical
5189 * case when invalidation is not used in redo or for
5190 * parallel read. The shared->excl upgrade loop at
5191 * the end of the function catches the race in a
5192 * reliable way (protected by the object lock).
5194 if (m->valid == VM_PAGE_BITS_ALL)
5197 poff = IDX_TO_OFF(m->pindex);
5198 poffe = MIN(poff + PAGE_SIZE, object->un_pager.vnp.vnp_size);
5199 for (; poff < poffe; poff += bsize) {
5200 lbn = get_lblkno(vp, poff);
5205 bsize = get_blksize(vp, lbn);
5206 error = bread_gb(vp, lbn, bsize, curthread->td_ucred,
5210 if (LIST_EMPTY(&bp->b_dep)) {
5212 * Invalidation clears m->valid, but
5213 * may leave B_CACHE flag if the
5214 * buffer existed at the invalidation
5215 * time. In this case, recycle the
5216 * buffer to do real read on next
5217 * bread() after redo.
5219 * Otherwise B_RELBUF is not strictly
5220 * necessary, enable to reduce buf
5223 if (buf_pager_relbuf ||
5224 m->valid != VM_PAGE_BITS_ALL)
5225 bp->b_flags |= B_RELBUF;
5227 bp->b_flags &= ~B_NOCACHE;
5233 KASSERT(1 /* racy, enable for debugging */ ||
5234 m->valid == VM_PAGE_BITS_ALL || i == count - 1,
5235 ("buf %d %p invalid", i, m));
5236 if (i == count - 1 && lpart) {
5237 VM_OBJECT_WLOCK(object);
5238 if (m->valid != 0 &&
5239 m->valid != VM_PAGE_BITS_ALL)
5240 vm_page_zero_invalid(m, TRUE);
5241 VM_OBJECT_WUNLOCK(object);
5247 VM_OBJECT_WLOCK(object);
5249 for (i = 0; i < count; i++) {
5250 vm_page_sunbusy(ma[i]);
5251 ma[i] = vm_page_grab(object, ma[i]->pindex, VM_ALLOC_NORMAL);
5254 * Since the pages were only sbusy while neither the
5255 * buffer nor the object lock was held by us, or
5256 * reallocated while vm_page_grab() slept for busy
5257 * relinguish, they could have been invalidated.
5258 * Recheck the valid bits and re-read as needed.
5260 * Note that the last page is made fully valid in the
5261 * read loop, and partial validity for the page at
5262 * index count - 1 could mean that the page was
5263 * invalidated or removed, so we must restart for
5266 if (ma[i]->valid != VM_PAGE_BITS_ALL)
5269 if (redo && error == 0)
5271 VM_OBJECT_WUNLOCK(object);
5272 return (error != 0 ? VM_PAGER_ERROR : VM_PAGER_OK);
5275 #include "opt_ddb.h"
5277 #include <ddb/ddb.h>
5279 /* DDB command to show buffer data */
5280 DB_SHOW_COMMAND(buffer, db_show_buffer)
5283 struct buf *bp = (struct buf *)addr;
5284 #ifdef FULL_BUF_TRACKING
5289 db_printf("usage: show buffer <addr>\n");
5293 db_printf("buf at %p\n", bp);
5294 db_printf("b_flags = 0x%b, b_xflags=0x%b, b_vflags=0x%b\n",
5295 (u_int)bp->b_flags, PRINT_BUF_FLAGS, (u_int)bp->b_xflags,
5296 PRINT_BUF_XFLAGS, (u_int)bp->b_vflags, PRINT_BUF_VFLAGS);
5298 "b_error = %d, b_bufsize = %ld, b_bcount = %ld, b_resid = %ld\n"
5299 "b_bufobj = (%p), b_data = %p, b_blkno = %jd, b_lblkno = %jd, "
5301 bp->b_error, bp->b_bufsize, bp->b_bcount, bp->b_resid,
5302 bp->b_bufobj, bp->b_data, (intmax_t)bp->b_blkno,
5303 (intmax_t)bp->b_lblkno, bp->b_dep.lh_first);
5304 db_printf("b_kvabase = %p, b_kvasize = %d\n",
5305 bp->b_kvabase, bp->b_kvasize);
5308 db_printf("b_npages = %d, pages(OBJ, IDX, PA): ", bp->b_npages);
5309 for (i = 0; i < bp->b_npages; i++) {
5313 db_printf("(%p, 0x%lx, 0x%lx)", m->object,
5315 (u_long)VM_PAGE_TO_PHYS(m));
5317 db_printf("( ??? )");
5318 if ((i + 1) < bp->b_npages)
5323 BUF_LOCKPRINTINFO(bp);
5324 #if defined(FULL_BUF_TRACKING)
5325 db_printf("b_io_tracking: b_io_tcnt = %u\n", bp->b_io_tcnt);
5327 i = bp->b_io_tcnt % BUF_TRACKING_SIZE;
5328 for (j = 1; j <= BUF_TRACKING_SIZE; j++) {
5329 if (bp->b_io_tracking[BUF_TRACKING_ENTRY(i - j)] == NULL)
5331 db_printf(" %2u: %s\n", j,
5332 bp->b_io_tracking[BUF_TRACKING_ENTRY(i - j)]);
5334 #elif defined(BUF_TRACKING)
5335 db_printf("b_io_tracking: %s\n", bp->b_io_tracking);
5340 DB_SHOW_COMMAND(bufqueues, bufqueues)
5342 struct bufdomain *bd;
5347 db_printf("bqempty: %d\n", bqempty.bq_len);
5349 for (i = 0; i < buf_domains; i++) {
5351 db_printf("Buf domain %d\n", i);
5352 db_printf("\tfreebufs\t%d\n", bd->bd_freebuffers);
5353 db_printf("\tlofreebufs\t%d\n", bd->bd_lofreebuffers);
5354 db_printf("\thifreebufs\t%d\n", bd->bd_hifreebuffers);
5356 db_printf("\tbufspace\t%ld\n", bd->bd_bufspace);
5357 db_printf("\tmaxbufspace\t%ld\n", bd->bd_maxbufspace);
5358 db_printf("\thibufspace\t%ld\n", bd->bd_hibufspace);
5359 db_printf("\tlobufspace\t%ld\n", bd->bd_lobufspace);
5360 db_printf("\tbufspacethresh\t%ld\n", bd->bd_bufspacethresh);
5362 db_printf("\tnumdirtybuffers\t%d\n", bd->bd_numdirtybuffers);
5363 db_printf("\tlodirtybuffers\t%d\n", bd->bd_lodirtybuffers);
5364 db_printf("\thidirtybuffers\t%d\n", bd->bd_hidirtybuffers);
5365 db_printf("\tdirtybufthresh\t%d\n", bd->bd_dirtybufthresh);
5368 TAILQ_FOREACH(bp, &bd->bd_cleanq->bq_queue, b_freelist)
5369 total += bp->b_bufsize;
5370 db_printf("\tcleanq count\t%d (%ld)\n",
5371 bd->bd_cleanq->bq_len, total);
5373 TAILQ_FOREACH(bp, &bd->bd_dirtyq.bq_queue, b_freelist)
5374 total += bp->b_bufsize;
5375 db_printf("\tdirtyq count\t%d (%ld)\n",
5376 bd->bd_dirtyq.bq_len, total);
5377 db_printf("\twakeup\t\t%d\n", bd->bd_wanted);
5378 db_printf("\tlim\t\t%d\n", bd->bd_lim);
5379 db_printf("\tCPU ");
5380 for (j = 0; j <= mp_maxid; j++)
5381 db_printf("%d, ", bd->bd_subq[j].bq_len);
5385 for (j = 0; j < nbuf; j++)
5386 if (buf[j].b_domain == i && BUF_ISLOCKED(&buf[j])) {
5388 total += buf[j].b_bufsize;
5390 db_printf("\tLocked buffers: %d space %ld\n", cnt, total);
5393 for (j = 0; j < nbuf; j++)
5394 if (buf[j].b_domain == i) {
5396 total += buf[j].b_bufsize;
5398 db_printf("\tTotal buffers: %d space %ld\n", cnt, total);
5402 DB_SHOW_COMMAND(lockedbufs, lockedbufs)
5407 for (i = 0; i < nbuf; i++) {
5409 if (BUF_ISLOCKED(bp)) {
5410 db_show_buffer((uintptr_t)bp, 1, 0, NULL);
5418 DB_SHOW_COMMAND(vnodebufs, db_show_vnodebufs)
5424 db_printf("usage: show vnodebufs <addr>\n");
5427 vp = (struct vnode *)addr;
5428 db_printf("Clean buffers:\n");
5429 TAILQ_FOREACH(bp, &vp->v_bufobj.bo_clean.bv_hd, b_bobufs) {
5430 db_show_buffer((uintptr_t)bp, 1, 0, NULL);
5433 db_printf("Dirty buffers:\n");
5434 TAILQ_FOREACH(bp, &vp->v_bufobj.bo_dirty.bv_hd, b_bobufs) {
5435 db_show_buffer((uintptr_t)bp, 1, 0, NULL);
5440 DB_COMMAND(countfreebufs, db_coundfreebufs)
5443 int i, used = 0, nfree = 0;
5446 db_printf("usage: countfreebufs\n");
5450 for (i = 0; i < nbuf; i++) {
5452 if (bp->b_qindex == QUEUE_EMPTY)
5458 db_printf("Counted %d free, %d used (%d tot)\n", nfree, used,
5460 db_printf("numfreebuffers is %d\n", numfreebuffers);