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>
90 static MALLOC_DEFINE(M_BIOBUF, "biobuf", "BIO buffer");
92 struct bio_ops bioops; /* I/O operation notification */
94 struct buf_ops buf_ops_bio = {
95 .bop_name = "buf_ops_bio",
96 .bop_write = bufwrite,
97 .bop_strategy = bufstrategy,
99 .bop_bdflush = bufbdflush,
103 struct mtx_padalign bq_lock;
104 TAILQ_HEAD(, buf) bq_queue;
106 uint16_t bq_subqueue;
108 } __aligned(CACHE_LINE_SIZE);
110 #define BQ_LOCKPTR(bq) (&(bq)->bq_lock)
111 #define BQ_LOCK(bq) mtx_lock(BQ_LOCKPTR((bq)))
112 #define BQ_UNLOCK(bq) mtx_unlock(BQ_LOCKPTR((bq)))
113 #define BQ_ASSERT_LOCKED(bq) mtx_assert(BQ_LOCKPTR((bq)), MA_OWNED)
116 struct bufqueue bd_subq[MAXCPU + 1]; /* Per-cpu sub queues + global */
117 struct bufqueue bd_dirtyq;
118 struct bufqueue *bd_cleanq;
119 struct mtx_padalign bd_run_lock;
124 long bd_bufspacethresh;
125 int bd_hifreebuffers;
126 int bd_lofreebuffers;
127 int bd_hidirtybuffers;
128 int bd_lodirtybuffers;
129 int bd_dirtybufthresh;
133 int __aligned(CACHE_LINE_SIZE) bd_numdirtybuffers;
134 int __aligned(CACHE_LINE_SIZE) bd_running;
135 long __aligned(CACHE_LINE_SIZE) bd_bufspace;
136 int __aligned(CACHE_LINE_SIZE) bd_freebuffers;
137 } __aligned(CACHE_LINE_SIZE);
139 #define BD_LOCKPTR(bd) (&(bd)->bd_cleanq->bq_lock)
140 #define BD_LOCK(bd) mtx_lock(BD_LOCKPTR((bd)))
141 #define BD_UNLOCK(bd) mtx_unlock(BD_LOCKPTR((bd)))
142 #define BD_ASSERT_LOCKED(bd) mtx_assert(BD_LOCKPTR((bd)), MA_OWNED)
143 #define BD_RUN_LOCKPTR(bd) (&(bd)->bd_run_lock)
144 #define BD_RUN_LOCK(bd) mtx_lock(BD_RUN_LOCKPTR((bd)))
145 #define BD_RUN_UNLOCK(bd) mtx_unlock(BD_RUN_LOCKPTR((bd)))
146 #define BD_DOMAIN(bd) (bd - bdomain)
148 static struct buf *buf; /* buffer header pool */
149 extern struct buf *swbuf; /* Swap buffer header pool. */
150 caddr_t unmapped_buf;
152 /* Used below and for softdep flushing threads in ufs/ffs/ffs_softdep.c */
153 struct proc *bufdaemonproc;
155 static int inmem(struct vnode *vp, daddr_t blkno);
156 static void vm_hold_free_pages(struct buf *bp, int newbsize);
157 static void vm_hold_load_pages(struct buf *bp, vm_offset_t from,
159 static void vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, vm_page_t m);
160 static void vfs_page_set_validclean(struct buf *bp, vm_ooffset_t off,
162 static void vfs_clean_pages_dirty_buf(struct buf *bp);
163 static void vfs_setdirty_locked_object(struct buf *bp);
164 static void vfs_vmio_invalidate(struct buf *bp);
165 static void vfs_vmio_truncate(struct buf *bp, int npages);
166 static void vfs_vmio_extend(struct buf *bp, int npages, int size);
167 static int vfs_bio_clcheck(struct vnode *vp, int size,
168 daddr_t lblkno, daddr_t blkno);
169 static void breada(struct vnode *, daddr_t *, int *, int, struct ucred *, int,
170 void (*)(struct buf *));
171 static int buf_flush(struct vnode *vp, struct bufdomain *, int);
172 static int flushbufqueues(struct vnode *, struct bufdomain *, int, int);
173 static void buf_daemon(void);
174 static __inline void bd_wakeup(void);
175 static int sysctl_runningspace(SYSCTL_HANDLER_ARGS);
176 static void bufkva_reclaim(vmem_t *, int);
177 static void bufkva_free(struct buf *);
178 static int buf_import(void *, void **, int, int, int);
179 static void buf_release(void *, void **, int);
180 static void maxbcachebuf_adjust(void);
181 static inline struct bufdomain *bufdomain(struct buf *);
182 static void bq_remove(struct bufqueue *bq, struct buf *bp);
183 static void bq_insert(struct bufqueue *bq, struct buf *bp, bool unlock);
184 static int buf_recycle(struct bufdomain *, bool kva);
185 static void bq_init(struct bufqueue *bq, int qindex, int cpu,
186 const char *lockname);
187 static void bd_init(struct bufdomain *bd);
188 static int bd_flushall(struct bufdomain *bd);
189 static int sysctl_bufdomain_long(SYSCTL_HANDLER_ARGS);
190 static int sysctl_bufdomain_int(SYSCTL_HANDLER_ARGS);
192 static int sysctl_bufspace(SYSCTL_HANDLER_ARGS);
193 int vmiodirenable = TRUE;
194 SYSCTL_INT(_vfs, OID_AUTO, vmiodirenable, CTLFLAG_RW, &vmiodirenable, 0,
195 "Use the VM system for directory writes");
196 long runningbufspace;
197 SYSCTL_LONG(_vfs, OID_AUTO, runningbufspace, CTLFLAG_RD, &runningbufspace, 0,
198 "Amount of presently outstanding async buffer io");
199 SYSCTL_PROC(_vfs, OID_AUTO, bufspace, CTLTYPE_LONG|CTLFLAG_MPSAFE|CTLFLAG_RD,
200 NULL, 0, sysctl_bufspace, "L", "Physical memory used for buffers");
201 static counter_u64_t bufkvaspace;
202 SYSCTL_COUNTER_U64(_vfs, OID_AUTO, bufkvaspace, CTLFLAG_RD, &bufkvaspace,
203 "Kernel virtual memory used for buffers");
204 static long maxbufspace;
205 SYSCTL_PROC(_vfs, OID_AUTO, maxbufspace,
206 CTLTYPE_LONG|CTLFLAG_MPSAFE|CTLFLAG_RW, &maxbufspace,
207 __offsetof(struct bufdomain, bd_maxbufspace), sysctl_bufdomain_long, "L",
208 "Maximum allowed value of bufspace (including metadata)");
209 static long bufmallocspace;
210 SYSCTL_LONG(_vfs, OID_AUTO, bufmallocspace, CTLFLAG_RD, &bufmallocspace, 0,
211 "Amount of malloced memory for buffers");
212 static long maxbufmallocspace;
213 SYSCTL_LONG(_vfs, OID_AUTO, maxmallocbufspace, CTLFLAG_RW, &maxbufmallocspace,
214 0, "Maximum amount of malloced memory for buffers");
215 static long lobufspace;
216 SYSCTL_PROC(_vfs, OID_AUTO, lobufspace,
217 CTLTYPE_LONG|CTLFLAG_MPSAFE|CTLFLAG_RW, &lobufspace,
218 __offsetof(struct bufdomain, bd_lobufspace), sysctl_bufdomain_long, "L",
219 "Minimum amount of buffers we want to have");
221 SYSCTL_PROC(_vfs, OID_AUTO, hibufspace,
222 CTLTYPE_LONG|CTLFLAG_MPSAFE|CTLFLAG_RW, &hibufspace,
223 __offsetof(struct bufdomain, bd_hibufspace), sysctl_bufdomain_long, "L",
224 "Maximum allowed value of bufspace (excluding metadata)");
226 SYSCTL_PROC(_vfs, OID_AUTO, bufspacethresh,
227 CTLTYPE_LONG|CTLFLAG_MPSAFE|CTLFLAG_RW, &bufspacethresh,
228 __offsetof(struct bufdomain, bd_bufspacethresh), sysctl_bufdomain_long, "L",
229 "Bufspace consumed before waking the daemon to free some");
230 static counter_u64_t buffreekvacnt;
231 SYSCTL_COUNTER_U64(_vfs, OID_AUTO, buffreekvacnt, CTLFLAG_RW, &buffreekvacnt,
232 "Number of times we have freed the KVA space from some buffer");
233 static counter_u64_t bufdefragcnt;
234 SYSCTL_COUNTER_U64(_vfs, OID_AUTO, bufdefragcnt, CTLFLAG_RW, &bufdefragcnt,
235 "Number of times we have had to repeat buffer allocation to defragment");
236 static long lorunningspace;
237 SYSCTL_PROC(_vfs, OID_AUTO, lorunningspace, CTLTYPE_LONG | CTLFLAG_MPSAFE |
238 CTLFLAG_RW, &lorunningspace, 0, sysctl_runningspace, "L",
239 "Minimum preferred space used for in-progress I/O");
240 static long hirunningspace;
241 SYSCTL_PROC(_vfs, OID_AUTO, hirunningspace, CTLTYPE_LONG | CTLFLAG_MPSAFE |
242 CTLFLAG_RW, &hirunningspace, 0, sysctl_runningspace, "L",
243 "Maximum amount of space to use for in-progress I/O");
244 int dirtybufferflushes;
245 SYSCTL_INT(_vfs, OID_AUTO, dirtybufferflushes, CTLFLAG_RW, &dirtybufferflushes,
246 0, "Number of bdwrite to bawrite conversions to limit dirty buffers");
248 SYSCTL_INT(_vfs, OID_AUTO, bdwriteskip, CTLFLAG_RW, &bdwriteskip,
249 0, "Number of buffers supplied to bdwrite with snapshot deadlock risk");
250 int altbufferflushes;
251 SYSCTL_INT(_vfs, OID_AUTO, altbufferflushes, CTLFLAG_RW, &altbufferflushes,
252 0, "Number of fsync flushes to limit dirty buffers");
253 static int recursiveflushes;
254 SYSCTL_INT(_vfs, OID_AUTO, recursiveflushes, CTLFLAG_RW, &recursiveflushes,
255 0, "Number of flushes skipped due to being recursive");
256 static int sysctl_numdirtybuffers(SYSCTL_HANDLER_ARGS);
257 SYSCTL_PROC(_vfs, OID_AUTO, numdirtybuffers,
258 CTLTYPE_INT|CTLFLAG_MPSAFE|CTLFLAG_RD, NULL, 0, sysctl_numdirtybuffers, "I",
259 "Number of buffers that are dirty (has unwritten changes) at the moment");
260 static int lodirtybuffers;
261 SYSCTL_PROC(_vfs, OID_AUTO, lodirtybuffers,
262 CTLTYPE_INT|CTLFLAG_MPSAFE|CTLFLAG_RW, &lodirtybuffers,
263 __offsetof(struct bufdomain, bd_lodirtybuffers), sysctl_bufdomain_int, "I",
264 "How many buffers we want to have free before bufdaemon can sleep");
265 static int hidirtybuffers;
266 SYSCTL_PROC(_vfs, OID_AUTO, hidirtybuffers,
267 CTLTYPE_INT|CTLFLAG_MPSAFE|CTLFLAG_RW, &hidirtybuffers,
268 __offsetof(struct bufdomain, bd_hidirtybuffers), sysctl_bufdomain_int, "I",
269 "When the number of dirty buffers is considered severe");
271 SYSCTL_PROC(_vfs, OID_AUTO, dirtybufthresh,
272 CTLTYPE_INT|CTLFLAG_MPSAFE|CTLFLAG_RW, &dirtybufthresh,
273 __offsetof(struct bufdomain, bd_dirtybufthresh), sysctl_bufdomain_int, "I",
274 "Number of bdwrite to bawrite conversions to clear dirty buffers");
275 static int numfreebuffers;
276 SYSCTL_INT(_vfs, OID_AUTO, numfreebuffers, CTLFLAG_RD, &numfreebuffers, 0,
277 "Number of free buffers");
278 static int lofreebuffers;
279 SYSCTL_PROC(_vfs, OID_AUTO, lofreebuffers,
280 CTLTYPE_INT|CTLFLAG_MPSAFE|CTLFLAG_RW, &lofreebuffers,
281 __offsetof(struct bufdomain, bd_lofreebuffers), sysctl_bufdomain_int, "I",
282 "Target number of free buffers");
283 static int hifreebuffers;
284 SYSCTL_PROC(_vfs, OID_AUTO, hifreebuffers,
285 CTLTYPE_INT|CTLFLAG_MPSAFE|CTLFLAG_RW, &hifreebuffers,
286 __offsetof(struct bufdomain, bd_hifreebuffers), sysctl_bufdomain_int, "I",
287 "Threshold for clean buffer recycling");
288 static counter_u64_t getnewbufcalls;
289 SYSCTL_COUNTER_U64(_vfs, OID_AUTO, getnewbufcalls, CTLFLAG_RD,
290 &getnewbufcalls, "Number of calls to getnewbuf");
291 static counter_u64_t getnewbufrestarts;
292 SYSCTL_COUNTER_U64(_vfs, OID_AUTO, getnewbufrestarts, CTLFLAG_RD,
294 "Number of times getnewbuf has had to restart a buffer acquisition");
295 static counter_u64_t mappingrestarts;
296 SYSCTL_COUNTER_U64(_vfs, OID_AUTO, mappingrestarts, CTLFLAG_RD,
298 "Number of times getblk has had to restart a buffer mapping for "
300 static counter_u64_t numbufallocfails;
301 SYSCTL_COUNTER_U64(_vfs, OID_AUTO, numbufallocfails, CTLFLAG_RW,
302 &numbufallocfails, "Number of times buffer allocations failed");
303 static int flushbufqtarget = 100;
304 SYSCTL_INT(_vfs, OID_AUTO, flushbufqtarget, CTLFLAG_RW, &flushbufqtarget, 0,
305 "Amount of work to do in flushbufqueues when helping bufdaemon");
306 static counter_u64_t notbufdflushes;
307 SYSCTL_COUNTER_U64(_vfs, OID_AUTO, notbufdflushes, CTLFLAG_RD, ¬bufdflushes,
308 "Number of dirty buffer flushes done by the bufdaemon helpers");
309 static long barrierwrites;
310 SYSCTL_LONG(_vfs, OID_AUTO, barrierwrites, CTLFLAG_RW, &barrierwrites, 0,
311 "Number of barrier writes");
312 SYSCTL_INT(_vfs, OID_AUTO, unmapped_buf_allowed, CTLFLAG_RD,
313 &unmapped_buf_allowed, 0,
314 "Permit the use of the unmapped i/o");
315 int maxbcachebuf = MAXBCACHEBUF;
316 SYSCTL_INT(_vfs, OID_AUTO, maxbcachebuf, CTLFLAG_RDTUN, &maxbcachebuf, 0,
317 "Maximum size of a buffer cache block");
320 * This lock synchronizes access to bd_request.
322 static struct mtx_padalign __exclusive_cache_line bdlock;
325 * This lock protects the runningbufreq and synchronizes runningbufwakeup and
326 * waitrunningbufspace().
328 static struct mtx_padalign __exclusive_cache_line rbreqlock;
331 * Lock that protects bdirtywait.
333 static struct mtx_padalign __exclusive_cache_line bdirtylock;
336 * Wakeup point for bufdaemon, as well as indicator of whether it is already
337 * active. Set to 1 when the bufdaemon is already "on" the queue, 0 when it
340 static int bd_request;
343 * Request for the buf daemon to write more buffers than is indicated by
344 * lodirtybuf. This may be necessary to push out excess dependencies or
345 * defragment the address space where a simple count of the number of dirty
346 * buffers is insufficient to characterize the demand for flushing them.
348 static int bd_speedupreq;
351 * Synchronization (sleep/wakeup) variable for active buffer space requests.
352 * Set when wait starts, cleared prior to wakeup().
353 * Used in runningbufwakeup() and waitrunningbufspace().
355 static int runningbufreq;
358 * Synchronization for bwillwrite() waiters.
360 static int bdirtywait;
363 * Definitions for the buffer free lists.
365 #define QUEUE_NONE 0 /* on no queue */
366 #define QUEUE_EMPTY 1 /* empty buffer headers */
367 #define QUEUE_DIRTY 2 /* B_DELWRI buffers */
368 #define QUEUE_CLEAN 3 /* non-B_DELWRI buffers */
369 #define QUEUE_SENTINEL 4 /* not an queue index, but mark for sentinel */
371 /* Maximum number of buffer domains. */
372 #define BUF_DOMAINS 8
374 struct bufdomainset bdlodirty; /* Domains > lodirty */
375 struct bufdomainset bdhidirty; /* Domains > hidirty */
377 /* Configured number of clean queues. */
378 static int __read_mostly buf_domains;
380 BITSET_DEFINE(bufdomainset, BUF_DOMAINS);
381 struct bufdomain __exclusive_cache_line bdomain[BUF_DOMAINS];
382 struct bufqueue __exclusive_cache_line bqempty;
385 * per-cpu empty buffer cache.
390 * Single global constant for BUF_WMESG, to avoid getting multiple references.
391 * buf_wmesg is referred from macros.
393 const char *buf_wmesg = BUF_WMESG;
396 sysctl_runningspace(SYSCTL_HANDLER_ARGS)
401 value = *(long *)arg1;
402 error = sysctl_handle_long(oidp, &value, 0, req);
403 if (error != 0 || req->newptr == NULL)
405 mtx_lock(&rbreqlock);
406 if (arg1 == &hirunningspace) {
407 if (value < lorunningspace)
410 hirunningspace = value;
412 KASSERT(arg1 == &lorunningspace,
413 ("%s: unknown arg1", __func__));
414 if (value > hirunningspace)
417 lorunningspace = value;
419 mtx_unlock(&rbreqlock);
424 sysctl_bufdomain_int(SYSCTL_HANDLER_ARGS)
430 value = *(int *)arg1;
431 error = sysctl_handle_int(oidp, &value, 0, req);
432 if (error != 0 || req->newptr == NULL)
434 *(int *)arg1 = value;
435 for (i = 0; i < buf_domains; i++)
436 *(int *)(uintptr_t)(((uintptr_t)&bdomain[i]) + arg2) =
443 sysctl_bufdomain_long(SYSCTL_HANDLER_ARGS)
449 value = *(long *)arg1;
450 error = sysctl_handle_long(oidp, &value, 0, req);
451 if (error != 0 || req->newptr == NULL)
453 *(long *)arg1 = value;
454 for (i = 0; i < buf_domains; i++)
455 *(long *)(uintptr_t)(((uintptr_t)&bdomain[i]) + arg2) =
461 #if defined(COMPAT_FREEBSD4) || defined(COMPAT_FREEBSD5) || \
462 defined(COMPAT_FREEBSD6) || defined(COMPAT_FREEBSD7)
464 sysctl_bufspace(SYSCTL_HANDLER_ARGS)
471 for (i = 0; i < buf_domains; i++)
472 lvalue += bdomain[i].bd_bufspace;
473 if (sizeof(int) == sizeof(long) || req->oldlen >= sizeof(long))
474 return (sysctl_handle_long(oidp, &lvalue, 0, req));
475 if (lvalue > INT_MAX)
476 /* On overflow, still write out a long to trigger ENOMEM. */
477 return (sysctl_handle_long(oidp, &lvalue, 0, req));
479 return (sysctl_handle_int(oidp, &ivalue, 0, req));
483 sysctl_bufspace(SYSCTL_HANDLER_ARGS)
489 for (i = 0; i < buf_domains; i++)
490 lvalue += bdomain[i].bd_bufspace;
491 return (sysctl_handle_long(oidp, &lvalue, 0, req));
496 sysctl_numdirtybuffers(SYSCTL_HANDLER_ARGS)
502 for (i = 0; i < buf_domains; i++)
503 value += bdomain[i].bd_numdirtybuffers;
504 return (sysctl_handle_int(oidp, &value, 0, req));
510 * Wakeup any bwillwrite() waiters.
515 mtx_lock(&bdirtylock);
520 mtx_unlock(&bdirtylock);
526 * Clear a domain from the appropriate bitsets when dirtybuffers
530 bd_clear(struct bufdomain *bd)
533 mtx_lock(&bdirtylock);
534 if (bd->bd_numdirtybuffers <= bd->bd_lodirtybuffers)
535 BIT_CLR(BUF_DOMAINS, BD_DOMAIN(bd), &bdlodirty);
536 if (bd->bd_numdirtybuffers <= bd->bd_hidirtybuffers)
537 BIT_CLR(BUF_DOMAINS, BD_DOMAIN(bd), &bdhidirty);
538 mtx_unlock(&bdirtylock);
544 * Set a domain in the appropriate bitsets when dirtybuffers
548 bd_set(struct bufdomain *bd)
551 mtx_lock(&bdirtylock);
552 if (bd->bd_numdirtybuffers > bd->bd_lodirtybuffers)
553 BIT_SET(BUF_DOMAINS, BD_DOMAIN(bd), &bdlodirty);
554 if (bd->bd_numdirtybuffers > bd->bd_hidirtybuffers)
555 BIT_SET(BUF_DOMAINS, BD_DOMAIN(bd), &bdhidirty);
556 mtx_unlock(&bdirtylock);
562 * Decrement the numdirtybuffers count by one and wakeup any
563 * threads blocked in bwillwrite().
566 bdirtysub(struct buf *bp)
568 struct bufdomain *bd;
572 num = atomic_fetchadd_int(&bd->bd_numdirtybuffers, -1);
573 if (num == (bd->bd_lodirtybuffers + bd->bd_hidirtybuffers) / 2)
575 if (num == bd->bd_lodirtybuffers || num == bd->bd_hidirtybuffers)
582 * Increment the numdirtybuffers count by one and wakeup the buf
586 bdirtyadd(struct buf *bp)
588 struct bufdomain *bd;
592 * Only do the wakeup once as we cross the boundary. The
593 * buf daemon will keep running until the condition clears.
596 num = atomic_fetchadd_int(&bd->bd_numdirtybuffers, 1);
597 if (num == (bd->bd_lodirtybuffers + bd->bd_hidirtybuffers) / 2)
599 if (num == bd->bd_lodirtybuffers || num == bd->bd_hidirtybuffers)
604 * bufspace_daemon_wakeup:
606 * Wakeup the daemons responsible for freeing clean bufs.
609 bufspace_daemon_wakeup(struct bufdomain *bd)
613 * avoid the lock if the daemon is running.
615 if (atomic_fetchadd_int(&bd->bd_running, 1) == 0) {
617 atomic_store_int(&bd->bd_running, 1);
618 wakeup(&bd->bd_running);
624 * bufspace_daemon_wait:
626 * Sleep until the domain falls below a limit or one second passes.
629 bufspace_daemon_wait(struct bufdomain *bd)
632 * Re-check our limits and sleep. bd_running must be
633 * cleared prior to checking the limits to avoid missed
634 * wakeups. The waker will adjust one of bufspace or
635 * freebuffers prior to checking bd_running.
638 atomic_store_int(&bd->bd_running, 0);
639 if (bd->bd_bufspace < bd->bd_bufspacethresh &&
640 bd->bd_freebuffers > bd->bd_lofreebuffers) {
641 msleep(&bd->bd_running, BD_RUN_LOCKPTR(bd), PRIBIO|PDROP,
644 /* Avoid spurious wakeups while running. */
645 atomic_store_int(&bd->bd_running, 1);
653 * Adjust the reported bufspace for a KVA managed buffer, possibly
654 * waking any waiters.
657 bufspace_adjust(struct buf *bp, int bufsize)
659 struct bufdomain *bd;
663 KASSERT((bp->b_flags & B_MALLOC) == 0,
664 ("bufspace_adjust: malloc buf %p", bp));
666 diff = bufsize - bp->b_bufsize;
668 atomic_subtract_long(&bd->bd_bufspace, -diff);
669 } else if (diff > 0) {
670 space = atomic_fetchadd_long(&bd->bd_bufspace, diff);
671 /* Wake up the daemon on the transition. */
672 if (space < bd->bd_bufspacethresh &&
673 space + diff >= bd->bd_bufspacethresh)
674 bufspace_daemon_wakeup(bd);
676 bp->b_bufsize = bufsize;
682 * Reserve bufspace before calling allocbuf(). metadata has a
683 * different space limit than data.
686 bufspace_reserve(struct bufdomain *bd, int size, bool metadata)
692 limit = bd->bd_maxbufspace;
694 limit = bd->bd_hibufspace;
695 space = atomic_fetchadd_long(&bd->bd_bufspace, size);
698 atomic_subtract_long(&bd->bd_bufspace, size);
702 /* Wake up the daemon on the transition. */
703 if (space < bd->bd_bufspacethresh && new >= bd->bd_bufspacethresh)
704 bufspace_daemon_wakeup(bd);
712 * Release reserved bufspace after bufspace_adjust() has consumed it.
715 bufspace_release(struct bufdomain *bd, int size)
718 atomic_subtract_long(&bd->bd_bufspace, size);
724 * Wait for bufspace, acting as the buf daemon if a locked vnode is
725 * supplied. bd_wanted must be set prior to polling for space. The
726 * operation must be re-tried on return.
729 bufspace_wait(struct bufdomain *bd, struct vnode *vp, int gbflags,
730 int slpflag, int slptimeo)
733 int error, fl, norunbuf;
735 if ((gbflags & GB_NOWAIT_BD) != 0)
740 while (bd->bd_wanted) {
741 if (vp != NULL && vp->v_type != VCHR &&
742 (td->td_pflags & TDP_BUFNEED) == 0) {
745 * getblk() is called with a vnode locked, and
746 * some majority of the dirty buffers may as
747 * well belong to the vnode. Flushing the
748 * buffers there would make a progress that
749 * cannot be achieved by the buf_daemon, that
750 * cannot lock the vnode.
752 norunbuf = ~(TDP_BUFNEED | TDP_NORUNNINGBUF) |
753 (td->td_pflags & TDP_NORUNNINGBUF);
756 * Play bufdaemon. The getnewbuf() function
757 * may be called while the thread owns lock
758 * for another dirty buffer for the same
759 * vnode, which makes it impossible to use
760 * VOP_FSYNC() there, due to the buffer lock
763 td->td_pflags |= TDP_BUFNEED | TDP_NORUNNINGBUF;
764 fl = buf_flush(vp, bd, flushbufqtarget);
765 td->td_pflags &= norunbuf;
769 if (bd->bd_wanted == 0)
772 error = msleep(&bd->bd_wanted, BD_LOCKPTR(bd),
773 (PRIBIO + 4) | slpflag, "newbuf", slptimeo);
784 * buffer space management daemon. Tries to maintain some marginal
785 * amount of free buffer space so that requesting processes neither
786 * block nor work to reclaim buffers.
789 bufspace_daemon(void *arg)
791 struct bufdomain *bd;
793 EVENTHANDLER_REGISTER(shutdown_pre_sync, kthread_shutdown, curthread,
794 SHUTDOWN_PRI_LAST + 100);
798 kthread_suspend_check();
801 * Free buffers from the clean queue until we meet our
804 * Theory of operation: The buffer cache is most efficient
805 * when some free buffer headers and space are always
806 * available to getnewbuf(). This daemon attempts to prevent
807 * the excessive blocking and synchronization associated
808 * with shortfall. It goes through three phases according
811 * 1) The daemon wakes up voluntarily once per-second
812 * during idle periods when the counters are below
813 * the wakeup thresholds (bufspacethresh, lofreebuffers).
815 * 2) The daemon wakes up as we cross the thresholds
816 * ahead of any potential blocking. This may bounce
817 * slightly according to the rate of consumption and
820 * 3) The daemon and consumers are starved for working
821 * clean buffers. This is the 'bufspace' sleep below
822 * which will inefficiently trade bufs with bqrelse
823 * until we return to condition 2.
825 while (bd->bd_bufspace > bd->bd_lobufspace ||
826 bd->bd_freebuffers < bd->bd_hifreebuffers) {
827 if (buf_recycle(bd, false) != 0) {
831 * Speedup dirty if we've run out of clean
832 * buffers. This is possible in particular
833 * because softdep may held many bufs locked
834 * pending writes to other bufs which are
835 * marked for delayed write, exhausting
836 * clean space until they are written.
841 msleep(&bd->bd_wanted, BD_LOCKPTR(bd),
842 PRIBIO|PDROP, "bufspace", hz/10);
848 bufspace_daemon_wait(bd);
855 * Adjust the reported bufspace for a malloc managed buffer, possibly
856 * waking any waiters.
859 bufmallocadjust(struct buf *bp, int bufsize)
863 KASSERT((bp->b_flags & B_MALLOC) != 0,
864 ("bufmallocadjust: non-malloc buf %p", bp));
865 diff = bufsize - bp->b_bufsize;
867 atomic_subtract_long(&bufmallocspace, -diff);
869 atomic_add_long(&bufmallocspace, diff);
870 bp->b_bufsize = bufsize;
876 * Wake up processes that are waiting on asynchronous writes to fall
877 * below lorunningspace.
883 mtx_lock(&rbreqlock);
886 wakeup(&runningbufreq);
888 mtx_unlock(&rbreqlock);
894 * Decrement the outstanding write count according.
897 runningbufwakeup(struct buf *bp)
901 bspace = bp->b_runningbufspace;
904 space = atomic_fetchadd_long(&runningbufspace, -bspace);
905 KASSERT(space >= bspace, ("runningbufspace underflow %ld %ld",
907 bp->b_runningbufspace = 0;
909 * Only acquire the lock and wakeup on the transition from exceeding
910 * the threshold to falling below it.
912 if (space < lorunningspace)
914 if (space - bspace > lorunningspace)
920 * waitrunningbufspace()
922 * runningbufspace is a measure of the amount of I/O currently
923 * running. This routine is used in async-write situations to
924 * prevent creating huge backups of pending writes to a device.
925 * Only asynchronous writes are governed by this function.
927 * This does NOT turn an async write into a sync write. It waits
928 * for earlier writes to complete and generally returns before the
929 * caller's write has reached the device.
932 waitrunningbufspace(void)
935 mtx_lock(&rbreqlock);
936 while (runningbufspace > hirunningspace) {
938 msleep(&runningbufreq, &rbreqlock, PVM, "wdrain", 0);
940 mtx_unlock(&rbreqlock);
945 * vfs_buf_test_cache:
947 * Called when a buffer is extended. This function clears the B_CACHE
948 * bit if the newly extended portion of the buffer does not contain
952 vfs_buf_test_cache(struct buf *bp, vm_ooffset_t foff, vm_offset_t off,
953 vm_offset_t size, vm_page_t m)
956 VM_OBJECT_ASSERT_LOCKED(m->object);
957 if (bp->b_flags & B_CACHE) {
958 int base = (foff + off) & PAGE_MASK;
959 if (vm_page_is_valid(m, base, size) == 0)
960 bp->b_flags &= ~B_CACHE;
964 /* Wake up the buffer daemon if necessary */
970 if (bd_request == 0) {
978 * Adjust the maxbcachbuf tunable.
981 maxbcachebuf_adjust(void)
986 * maxbcachebuf must be a power of 2 >= MAXBSIZE.
989 while (i * 2 <= maxbcachebuf)
992 if (maxbcachebuf < MAXBSIZE)
993 maxbcachebuf = MAXBSIZE;
994 if (maxbcachebuf > MAXPHYS)
995 maxbcachebuf = MAXPHYS;
996 if (bootverbose != 0 && maxbcachebuf != MAXBCACHEBUF)
997 printf("maxbcachebuf=%d\n", maxbcachebuf);
1001 * bd_speedup - speedup the buffer cache flushing code
1010 if (bd_speedupreq == 0 || bd_request == 0)
1015 wakeup(&bd_request);
1016 mtx_unlock(&bdlock);
1020 #define TRANSIENT_DENOM 5
1022 #define TRANSIENT_DENOM 10
1026 * Calculating buffer cache scaling values and reserve space for buffer
1027 * headers. This is called during low level kernel initialization and
1028 * may be called more then once. We CANNOT write to the memory area
1029 * being reserved at this time.
1032 kern_vfs_bio_buffer_alloc(caddr_t v, long physmem_est)
1035 long maxbuf, maxbuf_sz, buf_sz, biotmap_sz;
1038 * physmem_est is in pages. Convert it to kilobytes (assumes
1039 * PAGE_SIZE is >= 1K)
1041 physmem_est = physmem_est * (PAGE_SIZE / 1024);
1043 maxbcachebuf_adjust();
1045 * The nominal buffer size (and minimum KVA allocation) is BKVASIZE.
1046 * For the first 64MB of ram nominally allocate sufficient buffers to
1047 * cover 1/4 of our ram. Beyond the first 64MB allocate additional
1048 * buffers to cover 1/10 of our ram over 64MB. When auto-sizing
1049 * the buffer cache we limit the eventual kva reservation to
1052 * factor represents the 1/4 x ram conversion.
1055 int factor = 4 * BKVASIZE / 1024;
1058 if (physmem_est > 4096)
1059 nbuf += min((physmem_est - 4096) / factor,
1061 if (physmem_est > 65536)
1062 nbuf += min((physmem_est - 65536) * 2 / (factor * 5),
1063 32 * 1024 * 1024 / (factor * 5));
1065 if (maxbcache && nbuf > maxbcache / BKVASIZE)
1066 nbuf = maxbcache / BKVASIZE;
1071 /* XXX Avoid unsigned long overflows later on with maxbufspace. */
1072 maxbuf = (LONG_MAX / 3) / BKVASIZE;
1073 if (nbuf > maxbuf) {
1075 printf("Warning: nbufs lowered from %d to %ld\n", nbuf,
1081 * Ideal allocation size for the transient bio submap is 10%
1082 * of the maximal space buffer map. This roughly corresponds
1083 * to the amount of the buffer mapped for typical UFS load.
1085 * Clip the buffer map to reserve space for the transient
1086 * BIOs, if its extent is bigger than 90% (80% on i386) of the
1087 * maximum buffer map extent on the platform.
1089 * The fall-back to the maxbuf in case of maxbcache unset,
1090 * allows to not trim the buffer KVA for the architectures
1091 * with ample KVA space.
1093 if (bio_transient_maxcnt == 0 && unmapped_buf_allowed) {
1094 maxbuf_sz = maxbcache != 0 ? maxbcache : maxbuf * BKVASIZE;
1095 buf_sz = (long)nbuf * BKVASIZE;
1096 if (buf_sz < maxbuf_sz / TRANSIENT_DENOM *
1097 (TRANSIENT_DENOM - 1)) {
1099 * There is more KVA than memory. Do not
1100 * adjust buffer map size, and assign the rest
1101 * of maxbuf to transient map.
1103 biotmap_sz = maxbuf_sz - buf_sz;
1106 * Buffer map spans all KVA we could afford on
1107 * this platform. Give 10% (20% on i386) of
1108 * the buffer map to the transient bio map.
1110 biotmap_sz = buf_sz / TRANSIENT_DENOM;
1111 buf_sz -= biotmap_sz;
1113 if (biotmap_sz / INT_MAX > MAXPHYS)
1114 bio_transient_maxcnt = INT_MAX;
1116 bio_transient_maxcnt = biotmap_sz / MAXPHYS;
1118 * Artificially limit to 1024 simultaneous in-flight I/Os
1119 * using the transient mapping.
1121 if (bio_transient_maxcnt > 1024)
1122 bio_transient_maxcnt = 1024;
1124 nbuf = buf_sz / BKVASIZE;
1128 nswbuf = min(nbuf / 4, 256);
1129 if (nswbuf < NSWBUF_MIN)
1130 nswbuf = NSWBUF_MIN;
1134 * Reserve space for the buffer cache buffers
1137 v = (caddr_t)(buf + nbuf);
1142 /* Initialize the buffer subsystem. Called before use of any buffers. */
1149 KASSERT(maxbcachebuf >= MAXBSIZE,
1150 ("maxbcachebuf (%d) must be >= MAXBSIZE (%d)\n", maxbcachebuf,
1152 bq_init(&bqempty, QUEUE_EMPTY, -1, "bufq empty lock");
1153 mtx_init(&rbreqlock, "runningbufspace lock", NULL, MTX_DEF);
1154 mtx_init(&bdlock, "buffer daemon lock", NULL, MTX_DEF);
1155 mtx_init(&bdirtylock, "dirty buf lock", NULL, MTX_DEF);
1157 unmapped_buf = (caddr_t)kva_alloc(MAXPHYS);
1159 /* finally, initialize each buffer header and stick on empty q */
1160 for (i = 0; i < nbuf; i++) {
1162 bzero(bp, sizeof *bp);
1163 bp->b_flags = B_INVAL;
1164 bp->b_rcred = NOCRED;
1165 bp->b_wcred = NOCRED;
1166 bp->b_qindex = QUEUE_NONE;
1168 bp->b_subqueue = mp_maxid + 1;
1170 bp->b_data = bp->b_kvabase = unmapped_buf;
1171 LIST_INIT(&bp->b_dep);
1173 bq_insert(&bqempty, bp, false);
1177 * maxbufspace is the absolute maximum amount of buffer space we are
1178 * allowed to reserve in KVM and in real terms. The absolute maximum
1179 * is nominally used by metadata. hibufspace is the nominal maximum
1180 * used by most other requests. The differential is required to
1181 * ensure that metadata deadlocks don't occur.
1183 * maxbufspace is based on BKVASIZE. Allocating buffers larger then
1184 * this may result in KVM fragmentation which is not handled optimally
1185 * by the system. XXX This is less true with vmem. We could use
1188 maxbufspace = (long)nbuf * BKVASIZE;
1189 hibufspace = lmax(3 * maxbufspace / 4, maxbufspace - maxbcachebuf * 10);
1190 lobufspace = (hibufspace / 20) * 19; /* 95% */
1191 bufspacethresh = lobufspace + (hibufspace - lobufspace) / 2;
1194 * Note: The 16 MiB upper limit for hirunningspace was chosen
1195 * arbitrarily and may need further tuning. It corresponds to
1196 * 128 outstanding write IO requests (if IO size is 128 KiB),
1197 * which fits with many RAID controllers' tagged queuing limits.
1198 * The lower 1 MiB limit is the historical upper limit for
1201 hirunningspace = lmax(lmin(roundup(hibufspace / 64, maxbcachebuf),
1202 16 * 1024 * 1024), 1024 * 1024);
1203 lorunningspace = roundup((hirunningspace * 2) / 3, maxbcachebuf);
1206 * Limit the amount of malloc memory since it is wired permanently into
1207 * the kernel space. Even though this is accounted for in the buffer
1208 * allocation, we don't want the malloced region to grow uncontrolled.
1209 * The malloc scheme improves memory utilization significantly on
1210 * average (small) directories.
1212 maxbufmallocspace = hibufspace / 20;
1215 * Reduce the chance of a deadlock occurring by limiting the number
1216 * of delayed-write dirty buffers we allow to stack up.
1218 hidirtybuffers = nbuf / 4 + 20;
1219 dirtybufthresh = hidirtybuffers * 9 / 10;
1221 * To support extreme low-memory systems, make sure hidirtybuffers
1222 * cannot eat up all available buffer space. This occurs when our
1223 * minimum cannot be met. We try to size hidirtybuffers to 3/4 our
1224 * buffer space assuming BKVASIZE'd buffers.
1226 while ((long)hidirtybuffers * BKVASIZE > 3 * hibufspace / 4) {
1227 hidirtybuffers >>= 1;
1229 lodirtybuffers = hidirtybuffers / 2;
1232 * lofreebuffers should be sufficient to avoid stalling waiting on
1233 * buf headers under heavy utilization. The bufs in per-cpu caches
1234 * are counted as free but will be unavailable to threads executing
1237 * hifreebuffers is the free target for the bufspace daemon. This
1238 * should be set appropriately to limit work per-iteration.
1240 lofreebuffers = MIN((nbuf / 25) + (20 * mp_ncpus), 128 * mp_ncpus);
1241 hifreebuffers = (3 * lofreebuffers) / 2;
1242 numfreebuffers = nbuf;
1244 /* Setup the kva and free list allocators. */
1245 vmem_set_reclaim(buffer_arena, bufkva_reclaim);
1246 buf_zone = uma_zcache_create("buf free cache", sizeof(struct buf),
1247 NULL, NULL, NULL, NULL, buf_import, buf_release, NULL, 0);
1250 * Size the clean queue according to the amount of buffer space.
1251 * One queue per-256mb up to the max. More queues gives better
1252 * concurrency but less accurate LRU.
1254 buf_domains = MIN(howmany(maxbufspace, 256*1024*1024), BUF_DOMAINS);
1255 for (i = 0 ; i < buf_domains; i++) {
1256 struct bufdomain *bd;
1260 bd->bd_freebuffers = nbuf / buf_domains;
1261 bd->bd_hifreebuffers = hifreebuffers / buf_domains;
1262 bd->bd_lofreebuffers = lofreebuffers / buf_domains;
1263 bd->bd_bufspace = 0;
1264 bd->bd_maxbufspace = maxbufspace / buf_domains;
1265 bd->bd_hibufspace = hibufspace / buf_domains;
1266 bd->bd_lobufspace = lobufspace / buf_domains;
1267 bd->bd_bufspacethresh = bufspacethresh / buf_domains;
1268 bd->bd_numdirtybuffers = 0;
1269 bd->bd_hidirtybuffers = hidirtybuffers / buf_domains;
1270 bd->bd_lodirtybuffers = lodirtybuffers / buf_domains;
1271 bd->bd_dirtybufthresh = dirtybufthresh / buf_domains;
1272 /* Don't allow more than 2% of bufs in the per-cpu caches. */
1273 bd->bd_lim = nbuf / buf_domains / 50 / mp_ncpus;
1275 getnewbufcalls = counter_u64_alloc(M_WAITOK);
1276 getnewbufrestarts = counter_u64_alloc(M_WAITOK);
1277 mappingrestarts = counter_u64_alloc(M_WAITOK);
1278 numbufallocfails = counter_u64_alloc(M_WAITOK);
1279 notbufdflushes = counter_u64_alloc(M_WAITOK);
1280 buffreekvacnt = counter_u64_alloc(M_WAITOK);
1281 bufdefragcnt = counter_u64_alloc(M_WAITOK);
1282 bufkvaspace = counter_u64_alloc(M_WAITOK);
1287 vfs_buf_check_mapped(struct buf *bp)
1290 KASSERT(bp->b_kvabase != unmapped_buf,
1291 ("mapped buf: b_kvabase was not updated %p", bp));
1292 KASSERT(bp->b_data != unmapped_buf,
1293 ("mapped buf: b_data was not updated %p", bp));
1294 KASSERT(bp->b_data < unmapped_buf || bp->b_data >= unmapped_buf +
1295 MAXPHYS, ("b_data + b_offset unmapped %p", bp));
1299 vfs_buf_check_unmapped(struct buf *bp)
1302 KASSERT(bp->b_data == unmapped_buf,
1303 ("unmapped buf: corrupted b_data %p", bp));
1306 #define BUF_CHECK_MAPPED(bp) vfs_buf_check_mapped(bp)
1307 #define BUF_CHECK_UNMAPPED(bp) vfs_buf_check_unmapped(bp)
1309 #define BUF_CHECK_MAPPED(bp) do {} while (0)
1310 #define BUF_CHECK_UNMAPPED(bp) do {} while (0)
1314 isbufbusy(struct buf *bp)
1316 if (((bp->b_flags & B_INVAL) == 0 && BUF_ISLOCKED(bp)) ||
1317 ((bp->b_flags & (B_DELWRI | B_INVAL)) == B_DELWRI))
1323 * Shutdown the system cleanly to prepare for reboot, halt, or power off.
1326 bufshutdown(int show_busybufs)
1328 static int first_buf_printf = 1;
1330 int iter, nbusy, pbusy;
1336 * Sync filesystems for shutdown
1338 wdog_kern_pat(WD_LASTVAL);
1339 sys_sync(curthread, NULL);
1342 * With soft updates, some buffers that are
1343 * written will be remarked as dirty until other
1344 * buffers are written.
1346 for (iter = pbusy = 0; iter < 20; iter++) {
1348 for (bp = &buf[nbuf]; --bp >= buf; )
1352 if (first_buf_printf)
1353 printf("All buffers synced.");
1356 if (first_buf_printf) {
1357 printf("Syncing disks, buffers remaining... ");
1358 first_buf_printf = 0;
1360 printf("%d ", nbusy);
1365 wdog_kern_pat(WD_LASTVAL);
1366 sys_sync(curthread, NULL);
1370 * Spin for a while to allow interrupt threads to run.
1372 DELAY(50000 * iter);
1375 * Context switch several times to allow interrupt
1378 for (subiter = 0; subiter < 50 * iter; subiter++) {
1379 thread_lock(curthread);
1380 mi_switch(SW_VOL, NULL);
1381 thread_unlock(curthread);
1388 * Count only busy local buffers to prevent forcing
1389 * a fsck if we're just a client of a wedged NFS server
1392 for (bp = &buf[nbuf]; --bp >= buf; ) {
1393 if (isbufbusy(bp)) {
1395 /* XXX: This is bogus. We should probably have a BO_REMOTE flag instead */
1396 if (bp->b_dev == NULL) {
1397 TAILQ_REMOVE(&mountlist,
1398 bp->b_vp->v_mount, mnt_list);
1403 if (show_busybufs > 0) {
1405 "%d: buf:%p, vnode:%p, flags:%0x, blkno:%jd, lblkno:%jd, buflock:",
1406 nbusy, bp, bp->b_vp, bp->b_flags,
1407 (intmax_t)bp->b_blkno,
1408 (intmax_t)bp->b_lblkno);
1409 BUF_LOCKPRINTINFO(bp);
1410 if (show_busybufs > 1)
1418 * Failed to sync all blocks. Indicate this and don't
1419 * unmount filesystems (thus forcing an fsck on reboot).
1421 printf("Giving up on %d buffers\n", nbusy);
1422 DELAY(5000000); /* 5 seconds */
1424 if (!first_buf_printf)
1425 printf("Final sync complete\n");
1427 * Unmount filesystems
1429 if (panicstr == NULL)
1433 DELAY(100000); /* wait for console output to finish */
1437 bpmap_qenter(struct buf *bp)
1440 BUF_CHECK_MAPPED(bp);
1443 * bp->b_data is relative to bp->b_offset, but
1444 * bp->b_offset may be offset into the first page.
1446 bp->b_data = (caddr_t)trunc_page((vm_offset_t)bp->b_data);
1447 pmap_qenter((vm_offset_t)bp->b_data, bp->b_pages, bp->b_npages);
1448 bp->b_data = (caddr_t)((vm_offset_t)bp->b_data |
1449 (vm_offset_t)(bp->b_offset & PAGE_MASK));
1452 static inline struct bufdomain *
1453 bufdomain(struct buf *bp)
1456 return (&bdomain[bp->b_domain]);
1459 static struct bufqueue *
1460 bufqueue(struct buf *bp)
1463 switch (bp->b_qindex) {
1466 case QUEUE_SENTINEL:
1471 return (&bufdomain(bp)->bd_dirtyq);
1473 return (&bufdomain(bp)->bd_subq[bp->b_subqueue]);
1477 panic("bufqueue(%p): Unhandled type %d\n", bp, bp->b_qindex);
1481 * Return the locked bufqueue that bp is a member of.
1483 static struct bufqueue *
1484 bufqueue_acquire(struct buf *bp)
1486 struct bufqueue *bq, *nbq;
1489 * bp can be pushed from a per-cpu queue to the
1490 * cleanq while we're waiting on the lock. Retry
1491 * if the queues don't match.
1509 * Insert the buffer into the appropriate free list. Requires a
1510 * locked buffer on entry and buffer is unlocked before return.
1513 binsfree(struct buf *bp, int qindex)
1515 struct bufdomain *bd;
1516 struct bufqueue *bq;
1518 KASSERT(qindex == QUEUE_CLEAN || qindex == QUEUE_DIRTY,
1519 ("binsfree: Invalid qindex %d", qindex));
1520 BUF_ASSERT_XLOCKED(bp);
1523 * Handle delayed bremfree() processing.
1525 if (bp->b_flags & B_REMFREE) {
1526 if (bp->b_qindex == qindex) {
1527 bp->b_flags |= B_REUSE;
1528 bp->b_flags &= ~B_REMFREE;
1532 bq = bufqueue_acquire(bp);
1537 if (qindex == QUEUE_CLEAN) {
1538 if (bd->bd_lim != 0)
1539 bq = &bd->bd_subq[PCPU_GET(cpuid)];
1543 bq = &bd->bd_dirtyq;
1544 bq_insert(bq, bp, true);
1550 * Free a buffer to the buf zone once it no longer has valid contents.
1553 buf_free(struct buf *bp)
1556 if (bp->b_flags & B_REMFREE)
1558 if (bp->b_vflags & BV_BKGRDINPROG)
1559 panic("losing buffer 1");
1560 if (bp->b_rcred != NOCRED) {
1561 crfree(bp->b_rcred);
1562 bp->b_rcred = NOCRED;
1564 if (bp->b_wcred != NOCRED) {
1565 crfree(bp->b_wcred);
1566 bp->b_wcred = NOCRED;
1568 if (!LIST_EMPTY(&bp->b_dep))
1571 atomic_add_int(&bufdomain(bp)->bd_freebuffers, 1);
1573 uma_zfree(buf_zone, bp);
1579 * Import bufs into the uma cache from the buf list. The system still
1580 * expects a static array of bufs and much of the synchronization
1581 * around bufs assumes type stable storage. As a result, UMA is used
1582 * only as a per-cpu cache of bufs still maintained on a global list.
1585 buf_import(void *arg, void **store, int cnt, int domain, int flags)
1591 for (i = 0; i < cnt; i++) {
1592 bp = TAILQ_FIRST(&bqempty.bq_queue);
1595 bq_remove(&bqempty, bp);
1598 BQ_UNLOCK(&bqempty);
1606 * Release bufs from the uma cache back to the buffer queues.
1609 buf_release(void *arg, void **store, int cnt)
1611 struct bufqueue *bq;
1617 for (i = 0; i < cnt; i++) {
1619 /* Inline bq_insert() to batch locking. */
1620 TAILQ_INSERT_TAIL(&bq->bq_queue, bp, b_freelist);
1621 bp->b_flags &= ~(B_AGE | B_REUSE);
1623 bp->b_qindex = bq->bq_index;
1631 * Allocate an empty buffer header.
1634 buf_alloc(struct bufdomain *bd)
1640 * We can only run out of bufs in the buf zone if the average buf
1641 * is less than BKVASIZE. In this case the actual wait/block will
1642 * come from buf_reycle() failing to flush one of these small bufs.
1645 freebufs = atomic_fetchadd_int(&bd->bd_freebuffers, -1);
1647 bp = uma_zalloc(buf_zone, M_NOWAIT);
1649 atomic_add_int(&bd->bd_freebuffers, 1);
1650 bufspace_daemon_wakeup(bd);
1651 counter_u64_add(numbufallocfails, 1);
1655 * Wake-up the bufspace daemon on transition below threshold.
1657 if (freebufs == bd->bd_lofreebuffers)
1658 bufspace_daemon_wakeup(bd);
1660 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0)
1661 panic("getnewbuf_empty: Locked buf %p on free queue.", bp);
1663 KASSERT(bp->b_vp == NULL,
1664 ("bp: %p still has vnode %p.", bp, bp->b_vp));
1665 KASSERT((bp->b_flags & (B_DELWRI | B_NOREUSE)) == 0,
1666 ("invalid buffer %p flags %#x", bp, bp->b_flags));
1667 KASSERT((bp->b_xflags & (BX_VNCLEAN|BX_VNDIRTY)) == 0,
1668 ("bp: %p still on a buffer list. xflags %X", bp, bp->b_xflags));
1669 KASSERT(bp->b_npages == 0,
1670 ("bp: %p still has %d vm pages\n", bp, bp->b_npages));
1671 KASSERT(bp->b_kvasize == 0, ("bp: %p still has kva\n", bp));
1672 KASSERT(bp->b_bufsize == 0, ("bp: %p still has bufspace\n", bp));
1674 bp->b_domain = BD_DOMAIN(bd);
1680 bp->b_blkno = bp->b_lblkno = 0;
1681 bp->b_offset = NOOFFSET;
1687 bp->b_dirtyoff = bp->b_dirtyend = 0;
1688 bp->b_bufobj = NULL;
1689 bp->b_data = bp->b_kvabase = unmapped_buf;
1690 bp->b_fsprivate1 = NULL;
1691 bp->b_fsprivate2 = NULL;
1692 bp->b_fsprivate3 = NULL;
1693 LIST_INIT(&bp->b_dep);
1701 * Free a buffer from the given bufqueue. kva controls whether the
1702 * freed buf must own some kva resources. This is used for
1706 buf_recycle(struct bufdomain *bd, bool kva)
1708 struct bufqueue *bq;
1709 struct buf *bp, *nbp;
1712 counter_u64_add(bufdefragcnt, 1);
1716 KASSERT(BQ_LOCKPTR(bq) == BD_LOCKPTR(bd),
1717 ("buf_recycle: Locks don't match"));
1718 nbp = TAILQ_FIRST(&bq->bq_queue);
1721 * Run scan, possibly freeing data and/or kva mappings on the fly
1724 while ((bp = nbp) != NULL) {
1726 * Calculate next bp (we can only use it if we do not
1727 * release the bqlock).
1729 nbp = TAILQ_NEXT(bp, b_freelist);
1732 * If we are defragging then we need a buffer with
1733 * some kva to reclaim.
1735 if (kva && bp->b_kvasize == 0)
1738 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0)
1742 * Implement a second chance algorithm for frequently
1745 if ((bp->b_flags & B_REUSE) != 0) {
1746 TAILQ_REMOVE(&bq->bq_queue, bp, b_freelist);
1747 TAILQ_INSERT_TAIL(&bq->bq_queue, bp, b_freelist);
1748 bp->b_flags &= ~B_REUSE;
1754 * Skip buffers with background writes in progress.
1756 if ((bp->b_vflags & BV_BKGRDINPROG) != 0) {
1761 KASSERT(bp->b_qindex == QUEUE_CLEAN,
1762 ("buf_recycle: inconsistent queue %d bp %p",
1764 KASSERT(bp->b_domain == BD_DOMAIN(bd),
1765 ("getnewbuf: queue domain %d doesn't match request %d",
1766 bp->b_domain, (int)BD_DOMAIN(bd)));
1768 * NOTE: nbp is now entirely invalid. We can only restart
1769 * the scan from this point on.
1775 * Requeue the background write buffer with error and
1778 if ((bp->b_vflags & BV_BKGRDERR) != 0) {
1781 nbp = TAILQ_FIRST(&bq->bq_queue);
1784 bp->b_flags |= B_INVAL;
1797 * Mark the buffer for removal from the appropriate free list.
1801 bremfree(struct buf *bp)
1804 CTR3(KTR_BUF, "bremfree(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
1805 KASSERT((bp->b_flags & B_REMFREE) == 0,
1806 ("bremfree: buffer %p already marked for delayed removal.", bp));
1807 KASSERT(bp->b_qindex != QUEUE_NONE,
1808 ("bremfree: buffer %p not on a queue.", bp));
1809 BUF_ASSERT_XLOCKED(bp);
1811 bp->b_flags |= B_REMFREE;
1817 * Force an immediate removal from a free list. Used only in nfs when
1818 * it abuses the b_freelist pointer.
1821 bremfreef(struct buf *bp)
1823 struct bufqueue *bq;
1825 bq = bufqueue_acquire(bp);
1831 bq_init(struct bufqueue *bq, int qindex, int subqueue, const char *lockname)
1834 mtx_init(&bq->bq_lock, lockname, NULL, MTX_DEF);
1835 TAILQ_INIT(&bq->bq_queue);
1837 bq->bq_index = qindex;
1838 bq->bq_subqueue = subqueue;
1842 bd_init(struct bufdomain *bd)
1846 bd->bd_cleanq = &bd->bd_subq[mp_maxid + 1];
1847 bq_init(bd->bd_cleanq, QUEUE_CLEAN, mp_maxid + 1, "bufq clean lock");
1848 bq_init(&bd->bd_dirtyq, QUEUE_DIRTY, -1, "bufq dirty lock");
1849 for (i = 0; i <= mp_maxid; i++)
1850 bq_init(&bd->bd_subq[i], QUEUE_CLEAN, i,
1851 "bufq clean subqueue lock");
1852 mtx_init(&bd->bd_run_lock, "bufspace daemon run lock", NULL, MTX_DEF);
1858 * Removes a buffer from the free list, must be called with the
1859 * correct qlock held.
1862 bq_remove(struct bufqueue *bq, struct buf *bp)
1865 CTR3(KTR_BUF, "bq_remove(%p) vp %p flags %X",
1866 bp, bp->b_vp, bp->b_flags);
1867 KASSERT(bp->b_qindex != QUEUE_NONE,
1868 ("bq_remove: buffer %p not on a queue.", bp));
1869 KASSERT(bufqueue(bp) == bq,
1870 ("bq_remove: Remove buffer %p from wrong queue.", bp));
1872 BQ_ASSERT_LOCKED(bq);
1873 if (bp->b_qindex != QUEUE_EMPTY) {
1874 BUF_ASSERT_XLOCKED(bp);
1876 KASSERT(bq->bq_len >= 1,
1877 ("queue %d underflow", bp->b_qindex));
1878 TAILQ_REMOVE(&bq->bq_queue, bp, b_freelist);
1880 bp->b_qindex = QUEUE_NONE;
1881 bp->b_flags &= ~(B_REMFREE | B_REUSE);
1885 bd_flush(struct bufdomain *bd, struct bufqueue *bq)
1889 BQ_ASSERT_LOCKED(bq);
1890 if (bq != bd->bd_cleanq) {
1892 while ((bp = TAILQ_FIRST(&bq->bq_queue)) != NULL) {
1893 TAILQ_REMOVE(&bq->bq_queue, bp, b_freelist);
1894 TAILQ_INSERT_TAIL(&bd->bd_cleanq->bq_queue, bp,
1896 bp->b_subqueue = bd->bd_cleanq->bq_subqueue;
1898 bd->bd_cleanq->bq_len += bq->bq_len;
1901 if (bd->bd_wanted) {
1903 wakeup(&bd->bd_wanted);
1905 if (bq != bd->bd_cleanq)
1910 bd_flushall(struct bufdomain *bd)
1912 struct bufqueue *bq;
1916 if (bd->bd_lim == 0)
1919 for (i = 0; i <= mp_maxid; i++) {
1920 bq = &bd->bd_subq[i];
1921 if (bq->bq_len == 0)
1933 bq_insert(struct bufqueue *bq, struct buf *bp, bool unlock)
1935 struct bufdomain *bd;
1937 if (bp->b_qindex != QUEUE_NONE)
1938 panic("bq_insert: free buffer %p onto another queue?", bp);
1941 if (bp->b_flags & B_AGE) {
1942 /* Place this buf directly on the real queue. */
1943 if (bq->bq_index == QUEUE_CLEAN)
1946 TAILQ_INSERT_HEAD(&bq->bq_queue, bp, b_freelist);
1949 TAILQ_INSERT_TAIL(&bq->bq_queue, bp, b_freelist);
1951 bp->b_flags &= ~(B_AGE | B_REUSE);
1953 bp->b_qindex = bq->bq_index;
1954 bp->b_subqueue = bq->bq_subqueue;
1957 * Unlock before we notify so that we don't wakeup a waiter that
1958 * fails a trylock on the buf and sleeps again.
1963 if (bp->b_qindex == QUEUE_CLEAN) {
1965 * Flush the per-cpu queue and notify any waiters.
1967 if (bd->bd_wanted || (bq != bd->bd_cleanq &&
1968 bq->bq_len >= bd->bd_lim))
1977 * Free the kva allocation for a buffer.
1981 bufkva_free(struct buf *bp)
1985 if (bp->b_kvasize == 0) {
1986 KASSERT(bp->b_kvabase == unmapped_buf &&
1987 bp->b_data == unmapped_buf,
1988 ("Leaked KVA space on %p", bp));
1989 } else if (buf_mapped(bp))
1990 BUF_CHECK_MAPPED(bp);
1992 BUF_CHECK_UNMAPPED(bp);
1994 if (bp->b_kvasize == 0)
1997 vmem_free(buffer_arena, (vm_offset_t)bp->b_kvabase, bp->b_kvasize);
1998 counter_u64_add(bufkvaspace, -bp->b_kvasize);
1999 counter_u64_add(buffreekvacnt, 1);
2000 bp->b_data = bp->b_kvabase = unmapped_buf;
2007 * Allocate the buffer KVA and set b_kvasize and b_kvabase.
2010 bufkva_alloc(struct buf *bp, int maxsize, int gbflags)
2015 KASSERT((gbflags & GB_UNMAPPED) == 0 || (gbflags & GB_KVAALLOC) != 0,
2016 ("Invalid gbflags 0x%x in %s", gbflags, __func__));
2021 error = vmem_alloc(buffer_arena, maxsize, M_BESTFIT | M_NOWAIT, &addr);
2024 * Buffer map is too fragmented. Request the caller
2025 * to defragment the map.
2029 bp->b_kvabase = (caddr_t)addr;
2030 bp->b_kvasize = maxsize;
2031 counter_u64_add(bufkvaspace, bp->b_kvasize);
2032 if ((gbflags & GB_UNMAPPED) != 0) {
2033 bp->b_data = unmapped_buf;
2034 BUF_CHECK_UNMAPPED(bp);
2036 bp->b_data = bp->b_kvabase;
2037 BUF_CHECK_MAPPED(bp);
2045 * Reclaim buffer kva by freeing buffers holding kva. This is a vmem
2046 * callback that fires to avoid returning failure.
2049 bufkva_reclaim(vmem_t *vmem, int flags)
2056 for (i = 0; i < 5; i++) {
2057 for (q = 0; q < buf_domains; q++)
2058 if (buf_recycle(&bdomain[q], true) != 0)
2067 * Attempt to initiate asynchronous I/O on read-ahead blocks. We must
2068 * clear BIO_ERROR and B_INVAL prior to initiating I/O . If B_CACHE is set,
2069 * the buffer is valid and we do not have to do anything.
2072 breada(struct vnode * vp, daddr_t * rablkno, int * rabsize, int cnt,
2073 struct ucred * cred, int flags, void (*ckhashfunc)(struct buf *))
2078 for (i = 0; i < cnt; i++, rablkno++, rabsize++) {
2079 if (inmem(vp, *rablkno))
2081 rabp = getblk(vp, *rablkno, *rabsize, 0, 0, 0);
2082 if ((rabp->b_flags & B_CACHE) != 0) {
2086 if (!TD_IS_IDLETHREAD(curthread)) {
2090 racct_add_buf(curproc, rabp, 0);
2091 PROC_UNLOCK(curproc);
2094 curthread->td_ru.ru_inblock++;
2096 rabp->b_flags |= B_ASYNC;
2097 rabp->b_flags &= ~B_INVAL;
2098 if ((flags & GB_CKHASH) != 0) {
2099 rabp->b_flags |= B_CKHASH;
2100 rabp->b_ckhashcalc = ckhashfunc;
2102 rabp->b_ioflags &= ~BIO_ERROR;
2103 rabp->b_iocmd = BIO_READ;
2104 if (rabp->b_rcred == NOCRED && cred != NOCRED)
2105 rabp->b_rcred = crhold(cred);
2106 vfs_busy_pages(rabp, 0);
2108 rabp->b_iooffset = dbtob(rabp->b_blkno);
2114 * Entry point for bread() and breadn() via #defines in sys/buf.h.
2116 * Get a buffer with the specified data. Look in the cache first. We
2117 * must clear BIO_ERROR and B_INVAL prior to initiating I/O. If B_CACHE
2118 * is set, the buffer is valid and we do not have to do anything, see
2119 * getblk(). Also starts asynchronous I/O on read-ahead blocks.
2121 * Always return a NULL buffer pointer (in bpp) when returning an error.
2124 breadn_flags(struct vnode *vp, daddr_t blkno, int size, daddr_t *rablkno,
2125 int *rabsize, int cnt, struct ucred *cred, int flags,
2126 void (*ckhashfunc)(struct buf *), struct buf **bpp)
2130 int error, readwait, rv;
2132 CTR3(KTR_BUF, "breadn(%p, %jd, %d)", vp, blkno, size);
2135 * Can only return NULL if GB_LOCK_NOWAIT or GB_SPARSE flags
2138 error = getblkx(vp, blkno, size, 0, 0, flags, &bp);
2143 flags &= ~GB_NOSPARSE;
2147 * If not found in cache, do some I/O
2150 if ((bp->b_flags & B_CACHE) == 0) {
2151 if (!TD_IS_IDLETHREAD(td)) {
2154 PROC_LOCK(td->td_proc);
2155 racct_add_buf(td->td_proc, bp, 0);
2156 PROC_UNLOCK(td->td_proc);
2159 td->td_ru.ru_inblock++;
2161 bp->b_iocmd = BIO_READ;
2162 bp->b_flags &= ~B_INVAL;
2163 if ((flags & GB_CKHASH) != 0) {
2164 bp->b_flags |= B_CKHASH;
2165 bp->b_ckhashcalc = ckhashfunc;
2167 bp->b_ioflags &= ~BIO_ERROR;
2168 if (bp->b_rcred == NOCRED && cred != NOCRED)
2169 bp->b_rcred = crhold(cred);
2170 vfs_busy_pages(bp, 0);
2171 bp->b_iooffset = dbtob(bp->b_blkno);
2177 * Attempt to initiate asynchronous I/O on read-ahead blocks.
2179 breada(vp, rablkno, rabsize, cnt, cred, flags, ckhashfunc);
2193 * Write, release buffer on completion. (Done by iodone
2194 * if async). Do not bother writing anything if the buffer
2197 * Note that we set B_CACHE here, indicating that buffer is
2198 * fully valid and thus cacheable. This is true even of NFS
2199 * now so we set it generally. This could be set either here
2200 * or in biodone() since the I/O is synchronous. We put it
2204 bufwrite(struct buf *bp)
2211 CTR3(KTR_BUF, "bufwrite(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
2212 if ((bp->b_bufobj->bo_flag & BO_DEAD) != 0) {
2213 bp->b_flags |= B_INVAL | B_RELBUF;
2214 bp->b_flags &= ~B_CACHE;
2218 if (bp->b_flags & B_INVAL) {
2223 if (bp->b_flags & B_BARRIER)
2224 atomic_add_long(&barrierwrites, 1);
2226 oldflags = bp->b_flags;
2228 BUF_ASSERT_HELD(bp);
2230 KASSERT(!(bp->b_vflags & BV_BKGRDINPROG),
2231 ("FFS background buffer should not get here %p", bp));
2235 vp_md = vp->v_vflag & VV_MD;
2240 * Mark the buffer clean. Increment the bufobj write count
2241 * before bundirty() call, to prevent other thread from seeing
2242 * empty dirty list and zero counter for writes in progress,
2243 * falsely indicating that the bufobj is clean.
2245 bufobj_wref(bp->b_bufobj);
2248 bp->b_flags &= ~B_DONE;
2249 bp->b_ioflags &= ~BIO_ERROR;
2250 bp->b_flags |= B_CACHE;
2251 bp->b_iocmd = BIO_WRITE;
2253 vfs_busy_pages(bp, 1);
2256 * Normal bwrites pipeline writes
2258 bp->b_runningbufspace = bp->b_bufsize;
2259 space = atomic_fetchadd_long(&runningbufspace, bp->b_runningbufspace);
2261 if (!TD_IS_IDLETHREAD(curthread)) {
2265 racct_add_buf(curproc, bp, 1);
2266 PROC_UNLOCK(curproc);
2269 curthread->td_ru.ru_oublock++;
2271 if (oldflags & B_ASYNC)
2273 bp->b_iooffset = dbtob(bp->b_blkno);
2274 buf_track(bp, __func__);
2277 if ((oldflags & B_ASYNC) == 0) {
2278 int rtval = bufwait(bp);
2281 } else if (space > hirunningspace) {
2283 * don't allow the async write to saturate the I/O
2284 * system. We will not deadlock here because
2285 * we are blocking waiting for I/O that is already in-progress
2286 * to complete. We do not block here if it is the update
2287 * or syncer daemon trying to clean up as that can lead
2290 if ((curthread->td_pflags & TDP_NORUNNINGBUF) == 0 && !vp_md)
2291 waitrunningbufspace();
2298 bufbdflush(struct bufobj *bo, struct buf *bp)
2302 if (bo->bo_dirty.bv_cnt > dirtybufthresh + 10) {
2303 (void) VOP_FSYNC(bp->b_vp, MNT_NOWAIT, curthread);
2305 } else if (bo->bo_dirty.bv_cnt > dirtybufthresh) {
2308 * Try to find a buffer to flush.
2310 TAILQ_FOREACH(nbp, &bo->bo_dirty.bv_hd, b_bobufs) {
2311 if ((nbp->b_vflags & BV_BKGRDINPROG) ||
2313 LK_EXCLUSIVE | LK_NOWAIT, NULL))
2316 panic("bdwrite: found ourselves");
2318 /* Don't countdeps with the bo lock held. */
2319 if (buf_countdeps(nbp, 0)) {
2324 if (nbp->b_flags & B_CLUSTEROK) {
2325 vfs_bio_awrite(nbp);
2330 dirtybufferflushes++;
2339 * Delayed write. (Buffer is marked dirty). Do not bother writing
2340 * anything if the buffer is marked invalid.
2342 * Note that since the buffer must be completely valid, we can safely
2343 * set B_CACHE. In fact, we have to set B_CACHE here rather then in
2344 * biodone() in order to prevent getblk from writing the buffer
2345 * out synchronously.
2348 bdwrite(struct buf *bp)
2350 struct thread *td = curthread;
2354 CTR3(KTR_BUF, "bdwrite(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
2355 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp));
2356 KASSERT((bp->b_flags & B_BARRIER) == 0,
2357 ("Barrier request in delayed write %p", bp));
2358 BUF_ASSERT_HELD(bp);
2360 if (bp->b_flags & B_INVAL) {
2366 * If we have too many dirty buffers, don't create any more.
2367 * If we are wildly over our limit, then force a complete
2368 * cleanup. Otherwise, just keep the situation from getting
2369 * out of control. Note that we have to avoid a recursive
2370 * disaster and not try to clean up after our own cleanup!
2374 if ((td->td_pflags & (TDP_COWINPROGRESS|TDP_INBDFLUSH)) == 0) {
2375 td->td_pflags |= TDP_INBDFLUSH;
2377 td->td_pflags &= ~TDP_INBDFLUSH;
2383 * Set B_CACHE, indicating that the buffer is fully valid. This is
2384 * true even of NFS now.
2386 bp->b_flags |= B_CACHE;
2389 * This bmap keeps the system from needing to do the bmap later,
2390 * perhaps when the system is attempting to do a sync. Since it
2391 * is likely that the indirect block -- or whatever other datastructure
2392 * that the filesystem needs is still in memory now, it is a good
2393 * thing to do this. Note also, that if the pageout daemon is
2394 * requesting a sync -- there might not be enough memory to do
2395 * the bmap then... So, this is important to do.
2397 if (vp->v_type != VCHR && bp->b_lblkno == bp->b_blkno) {
2398 VOP_BMAP(vp, bp->b_lblkno, NULL, &bp->b_blkno, NULL, NULL);
2401 buf_track(bp, __func__);
2404 * Set the *dirty* buffer range based upon the VM system dirty
2407 * Mark the buffer pages as clean. We need to do this here to
2408 * satisfy the vnode_pager and the pageout daemon, so that it
2409 * thinks that the pages have been "cleaned". Note that since
2410 * the pages are in a delayed write buffer -- the VFS layer
2411 * "will" see that the pages get written out on the next sync,
2412 * or perhaps the cluster will be completed.
2414 vfs_clean_pages_dirty_buf(bp);
2418 * note: we cannot initiate I/O from a bdwrite even if we wanted to,
2419 * due to the softdep code.
2426 * Turn buffer into delayed write request. We must clear BIO_READ and
2427 * B_RELBUF, and we must set B_DELWRI. We reassign the buffer to
2428 * itself to properly update it in the dirty/clean lists. We mark it
2429 * B_DONE to ensure that any asynchronization of the buffer properly
2430 * clears B_DONE ( else a panic will occur later ).
2432 * bdirty() is kinda like bdwrite() - we have to clear B_INVAL which
2433 * might have been set pre-getblk(). Unlike bwrite/bdwrite, bdirty()
2434 * should only be called if the buffer is known-good.
2436 * Since the buffer is not on a queue, we do not update the numfreebuffers
2439 * The buffer must be on QUEUE_NONE.
2442 bdirty(struct buf *bp)
2445 CTR3(KTR_BUF, "bdirty(%p) vp %p flags %X",
2446 bp, bp->b_vp, bp->b_flags);
2447 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp));
2448 KASSERT(bp->b_flags & B_REMFREE || bp->b_qindex == QUEUE_NONE,
2449 ("bdirty: buffer %p still on queue %d", bp, bp->b_qindex));
2450 BUF_ASSERT_HELD(bp);
2451 bp->b_flags &= ~(B_RELBUF);
2452 bp->b_iocmd = BIO_WRITE;
2454 if ((bp->b_flags & B_DELWRI) == 0) {
2455 bp->b_flags |= /* XXX B_DONE | */ B_DELWRI;
2464 * Clear B_DELWRI for buffer.
2466 * Since the buffer is not on a queue, we do not update the numfreebuffers
2469 * The buffer must be on QUEUE_NONE.
2473 bundirty(struct buf *bp)
2476 CTR3(KTR_BUF, "bundirty(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
2477 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp));
2478 KASSERT(bp->b_flags & B_REMFREE || bp->b_qindex == QUEUE_NONE,
2479 ("bundirty: buffer %p still on queue %d", bp, bp->b_qindex));
2480 BUF_ASSERT_HELD(bp);
2482 if (bp->b_flags & B_DELWRI) {
2483 bp->b_flags &= ~B_DELWRI;
2488 * Since it is now being written, we can clear its deferred write flag.
2490 bp->b_flags &= ~B_DEFERRED;
2496 * Asynchronous write. Start output on a buffer, but do not wait for
2497 * it to complete. The buffer is released when the output completes.
2499 * bwrite() ( or the VOP routine anyway ) is responsible for handling
2500 * B_INVAL buffers. Not us.
2503 bawrite(struct buf *bp)
2506 bp->b_flags |= B_ASYNC;
2513 * Asynchronous barrier write. Start output on a buffer, but do not
2514 * wait for it to complete. Place a write barrier after this write so
2515 * that this buffer and all buffers written before it are committed to
2516 * the disk before any buffers written after this write are committed
2517 * to the disk. The buffer is released when the output completes.
2520 babarrierwrite(struct buf *bp)
2523 bp->b_flags |= B_ASYNC | B_BARRIER;
2530 * Synchronous barrier write. Start output on a buffer and wait for
2531 * it to complete. Place a write barrier after this write so that
2532 * this buffer and all buffers written before it are committed to
2533 * the disk before any buffers written after this write are committed
2534 * to the disk. The buffer is released when the output completes.
2537 bbarrierwrite(struct buf *bp)
2540 bp->b_flags |= B_BARRIER;
2541 return (bwrite(bp));
2547 * Called prior to the locking of any vnodes when we are expecting to
2548 * write. We do not want to starve the buffer cache with too many
2549 * dirty buffers so we block here. By blocking prior to the locking
2550 * of any vnodes we attempt to avoid the situation where a locked vnode
2551 * prevents the various system daemons from flushing related buffers.
2557 if (buf_dirty_count_severe()) {
2558 mtx_lock(&bdirtylock);
2559 while (buf_dirty_count_severe()) {
2561 msleep(&bdirtywait, &bdirtylock, (PRIBIO + 4),
2564 mtx_unlock(&bdirtylock);
2569 * Return true if we have too many dirty buffers.
2572 buf_dirty_count_severe(void)
2575 return (!BIT_EMPTY(BUF_DOMAINS, &bdhidirty));
2581 * Release a busy buffer and, if requested, free its resources. The
2582 * buffer will be stashed in the appropriate bufqueue[] allowing it
2583 * to be accessed later as a cache entity or reused for other purposes.
2586 brelse(struct buf *bp)
2588 struct mount *v_mnt;
2592 * Many functions erroneously call brelse with a NULL bp under rare
2593 * error conditions. Simply return when called with a NULL bp.
2597 CTR3(KTR_BUF, "brelse(%p) vp %p flags %X",
2598 bp, bp->b_vp, bp->b_flags);
2599 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)),
2600 ("brelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp));
2601 KASSERT((bp->b_flags & B_VMIO) != 0 || (bp->b_flags & B_NOREUSE) == 0,
2602 ("brelse: non-VMIO buffer marked NOREUSE"));
2604 if (BUF_LOCKRECURSED(bp)) {
2606 * Do not process, in particular, do not handle the
2607 * B_INVAL/B_RELBUF and do not release to free list.
2613 if (bp->b_flags & B_MANAGED) {
2618 if ((bp->b_vflags & (BV_BKGRDINPROG | BV_BKGRDERR)) == BV_BKGRDERR) {
2619 BO_LOCK(bp->b_bufobj);
2620 bp->b_vflags &= ~BV_BKGRDERR;
2621 BO_UNLOCK(bp->b_bufobj);
2624 if (bp->b_iocmd == BIO_WRITE && (bp->b_ioflags & BIO_ERROR) &&
2625 (bp->b_error != ENXIO || !LIST_EMPTY(&bp->b_dep)) &&
2626 !(bp->b_flags & B_INVAL)) {
2628 * Failed write, redirty. All errors except ENXIO (which
2629 * means the device is gone) are treated as being
2632 * XXX Treating EIO as transient is not correct; the
2633 * contract with the local storage device drivers is that
2634 * they will only return EIO once the I/O is no longer
2635 * retriable. Network I/O also respects this through the
2636 * guarantees of TCP and/or the internal retries of NFS.
2637 * ENOMEM might be transient, but we also have no way of
2638 * knowing when its ok to retry/reschedule. In general,
2639 * this entire case should be made obsolete through better
2640 * error handling/recovery and resource scheduling.
2642 * Do this also for buffers that failed with ENXIO, but have
2643 * non-empty dependencies - the soft updates code might need
2644 * to access the buffer to untangle them.
2646 * Must clear BIO_ERROR to prevent pages from being scrapped.
2648 bp->b_ioflags &= ~BIO_ERROR;
2650 } else if ((bp->b_flags & (B_NOCACHE | B_INVAL)) ||
2651 (bp->b_ioflags & BIO_ERROR) || (bp->b_bufsize <= 0)) {
2653 * Either a failed read I/O, or we were asked to free or not
2654 * cache the buffer, or we failed to write to a device that's
2655 * no longer present.
2657 bp->b_flags |= B_INVAL;
2658 if (!LIST_EMPTY(&bp->b_dep))
2660 if (bp->b_flags & B_DELWRI)
2662 bp->b_flags &= ~(B_DELWRI | B_CACHE);
2663 if ((bp->b_flags & B_VMIO) == 0) {
2671 * We must clear B_RELBUF if B_DELWRI is set. If vfs_vmio_truncate()
2672 * is called with B_DELWRI set, the underlying pages may wind up
2673 * getting freed causing a previous write (bdwrite()) to get 'lost'
2674 * because pages associated with a B_DELWRI bp are marked clean.
2676 * We still allow the B_INVAL case to call vfs_vmio_truncate(), even
2677 * if B_DELWRI is set.
2679 if (bp->b_flags & B_DELWRI)
2680 bp->b_flags &= ~B_RELBUF;
2683 * VMIO buffer rundown. It is not very necessary to keep a VMIO buffer
2684 * constituted, not even NFS buffers now. Two flags effect this. If
2685 * B_INVAL, the struct buf is invalidated but the VM object is kept
2686 * around ( i.e. so it is trivial to reconstitute the buffer later ).
2688 * If BIO_ERROR or B_NOCACHE is set, pages in the VM object will be
2689 * invalidated. BIO_ERROR cannot be set for a failed write unless the
2690 * buffer is also B_INVAL because it hits the re-dirtying code above.
2692 * Normally we can do this whether a buffer is B_DELWRI or not. If
2693 * the buffer is an NFS buffer, it is tracking piecemeal writes or
2694 * the commit state and we cannot afford to lose the buffer. If the
2695 * buffer has a background write in progress, we need to keep it
2696 * around to prevent it from being reconstituted and starting a second
2700 v_mnt = bp->b_vp != NULL ? bp->b_vp->v_mount : NULL;
2702 if ((bp->b_flags & B_VMIO) && (bp->b_flags & B_NOCACHE ||
2703 (bp->b_ioflags & BIO_ERROR && bp->b_iocmd == BIO_READ)) &&
2704 (v_mnt == NULL || (v_mnt->mnt_vfc->vfc_flags & VFCF_NETWORK) == 0 ||
2705 vn_isdisk(bp->b_vp, NULL) || (bp->b_flags & B_DELWRI) == 0)) {
2706 vfs_vmio_invalidate(bp);
2710 if ((bp->b_flags & (B_INVAL | B_RELBUF)) != 0 ||
2711 (bp->b_flags & (B_DELWRI | B_NOREUSE)) == B_NOREUSE) {
2713 bp->b_flags &= ~B_NOREUSE;
2714 if (bp->b_vp != NULL)
2719 * If the buffer has junk contents signal it and eventually
2720 * clean up B_DELWRI and diassociate the vnode so that gbincore()
2723 if (bp->b_bufsize == 0 || (bp->b_ioflags & BIO_ERROR) != 0 ||
2724 (bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF)) != 0)
2725 bp->b_flags |= B_INVAL;
2726 if (bp->b_flags & B_INVAL) {
2727 if (bp->b_flags & B_DELWRI)
2733 buf_track(bp, __func__);
2735 /* buffers with no memory */
2736 if (bp->b_bufsize == 0) {
2740 /* buffers with junk contents */
2741 if (bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF) ||
2742 (bp->b_ioflags & BIO_ERROR)) {
2743 bp->b_xflags &= ~(BX_BKGRDWRITE | BX_ALTDATA);
2744 if (bp->b_vflags & BV_BKGRDINPROG)
2745 panic("losing buffer 2");
2746 qindex = QUEUE_CLEAN;
2747 bp->b_flags |= B_AGE;
2748 /* remaining buffers */
2749 } else if (bp->b_flags & B_DELWRI)
2750 qindex = QUEUE_DIRTY;
2752 qindex = QUEUE_CLEAN;
2754 if ((bp->b_flags & B_DELWRI) == 0 && (bp->b_xflags & BX_VNDIRTY))
2755 panic("brelse: not dirty");
2757 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_RELBUF | B_DIRECT);
2758 /* binsfree unlocks bp. */
2759 binsfree(bp, qindex);
2763 * Release a buffer back to the appropriate queue but do not try to free
2764 * it. The buffer is expected to be used again soon.
2766 * bqrelse() is used by bdwrite() to requeue a delayed write, and used by
2767 * biodone() to requeue an async I/O on completion. It is also used when
2768 * known good buffers need to be requeued but we think we may need the data
2771 * XXX we should be able to leave the B_RELBUF hint set on completion.
2774 bqrelse(struct buf *bp)
2778 CTR3(KTR_BUF, "bqrelse(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
2779 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)),
2780 ("bqrelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp));
2782 qindex = QUEUE_NONE;
2783 if (BUF_LOCKRECURSED(bp)) {
2784 /* do not release to free list */
2788 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF);
2790 if (bp->b_flags & B_MANAGED) {
2791 if (bp->b_flags & B_REMFREE)
2796 /* buffers with stale but valid contents */
2797 if ((bp->b_flags & B_DELWRI) != 0 || (bp->b_vflags & (BV_BKGRDINPROG |
2798 BV_BKGRDERR)) == BV_BKGRDERR) {
2799 BO_LOCK(bp->b_bufobj);
2800 bp->b_vflags &= ~BV_BKGRDERR;
2801 BO_UNLOCK(bp->b_bufobj);
2802 qindex = QUEUE_DIRTY;
2804 if ((bp->b_flags & B_DELWRI) == 0 &&
2805 (bp->b_xflags & BX_VNDIRTY))
2806 panic("bqrelse: not dirty");
2807 if ((bp->b_flags & B_NOREUSE) != 0) {
2811 qindex = QUEUE_CLEAN;
2813 buf_track(bp, __func__);
2814 /* binsfree unlocks bp. */
2815 binsfree(bp, qindex);
2819 buf_track(bp, __func__);
2825 * Complete I/O to a VMIO backed page. Validate the pages as appropriate,
2826 * restore bogus pages.
2829 vfs_vmio_iodone(struct buf *bp)
2834 struct vnode *vp __unused;
2835 int i, iosize, resid;
2838 obj = bp->b_bufobj->bo_object;
2839 KASSERT(obj->paging_in_progress >= bp->b_npages,
2840 ("vfs_vmio_iodone: paging in progress(%d) < b_npages(%d)",
2841 obj->paging_in_progress, bp->b_npages));
2844 KASSERT(vp->v_holdcnt > 0,
2845 ("vfs_vmio_iodone: vnode %p has zero hold count", vp));
2846 KASSERT(vp->v_object != NULL,
2847 ("vfs_vmio_iodone: vnode %p has no vm_object", vp));
2849 foff = bp->b_offset;
2850 KASSERT(bp->b_offset != NOOFFSET,
2851 ("vfs_vmio_iodone: bp %p has no buffer offset", bp));
2854 iosize = bp->b_bcount - bp->b_resid;
2855 VM_OBJECT_WLOCK(obj);
2856 for (i = 0; i < bp->b_npages; i++) {
2857 resid = ((foff + PAGE_SIZE) & ~(off_t)PAGE_MASK) - foff;
2862 * cleanup bogus pages, restoring the originals
2865 if (m == bogus_page) {
2867 m = vm_page_lookup(obj, OFF_TO_IDX(foff));
2869 panic("biodone: page disappeared!");
2871 } else if ((bp->b_iocmd == BIO_READ) && resid > 0) {
2873 * In the write case, the valid and clean bits are
2874 * already changed correctly ( see bdwrite() ), so we
2875 * only need to do this here in the read case.
2877 KASSERT((m->dirty & vm_page_bits(foff & PAGE_MASK,
2878 resid)) == 0, ("vfs_vmio_iodone: page %p "
2879 "has unexpected dirty bits", m));
2880 vfs_page_set_valid(bp, foff, m);
2882 KASSERT(OFF_TO_IDX(foff) == m->pindex,
2883 ("vfs_vmio_iodone: foff(%jd)/pindex(%ju) mismatch",
2884 (intmax_t)foff, (uintmax_t)m->pindex));
2887 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK;
2890 vm_object_pip_wakeupn(obj, bp->b_npages);
2891 VM_OBJECT_WUNLOCK(obj);
2892 if (bogus && buf_mapped(bp)) {
2893 BUF_CHECK_MAPPED(bp);
2894 pmap_qenter(trunc_page((vm_offset_t)bp->b_data),
2895 bp->b_pages, bp->b_npages);
2900 * Unwire a page held by a buf and either free it or update the page queues to
2901 * reflect its recent use.
2904 vfs_vmio_unwire(struct buf *bp, vm_page_t m)
2909 if (vm_page_unwire_noq(m)) {
2910 if ((bp->b_flags & B_DIRECT) != 0)
2911 freed = vm_page_try_to_free(m);
2916 * Use a racy check of the valid bits to determine
2917 * whether we can accelerate reclamation of the page.
2918 * The valid bits will be stable unless the page is
2919 * being mapped or is referenced by multiple buffers,
2920 * and in those cases we expect races to be rare. At
2921 * worst we will either accelerate reclamation of a
2922 * valid page and violate LRU, or unnecessarily defer
2923 * reclamation of an invalid page.
2925 * The B_NOREUSE flag marks data that is not expected to
2926 * be reused, so accelerate reclamation in that case
2927 * too. Otherwise, maintain LRU.
2929 if (m->valid == 0 || (bp->b_flags & B_NOREUSE) != 0)
2930 vm_page_deactivate_noreuse(m);
2931 else if (vm_page_active(m))
2932 vm_page_reference(m);
2934 vm_page_deactivate(m);
2941 * Perform page invalidation when a buffer is released. The fully invalid
2942 * pages will be reclaimed later in vfs_vmio_truncate().
2945 vfs_vmio_invalidate(struct buf *bp)
2949 int i, resid, poffset, presid;
2951 if (buf_mapped(bp)) {
2952 BUF_CHECK_MAPPED(bp);
2953 pmap_qremove(trunc_page((vm_offset_t)bp->b_data), bp->b_npages);
2955 BUF_CHECK_UNMAPPED(bp);
2957 * Get the base offset and length of the buffer. Note that
2958 * in the VMIO case if the buffer block size is not
2959 * page-aligned then b_data pointer may not be page-aligned.
2960 * But our b_pages[] array *IS* page aligned.
2962 * block sizes less then DEV_BSIZE (usually 512) are not
2963 * supported due to the page granularity bits (m->valid,
2964 * m->dirty, etc...).
2966 * See man buf(9) for more information
2968 obj = bp->b_bufobj->bo_object;
2969 resid = bp->b_bufsize;
2970 poffset = bp->b_offset & PAGE_MASK;
2971 VM_OBJECT_WLOCK(obj);
2972 for (i = 0; i < bp->b_npages; i++) {
2974 if (m == bogus_page)
2975 panic("vfs_vmio_invalidate: Unexpected bogus page.");
2976 bp->b_pages[i] = NULL;
2978 presid = resid > (PAGE_SIZE - poffset) ?
2979 (PAGE_SIZE - poffset) : resid;
2980 KASSERT(presid >= 0, ("brelse: extra page"));
2981 while (vm_page_xbusied(m)) {
2983 VM_OBJECT_WUNLOCK(obj);
2984 vm_page_busy_sleep(m, "mbncsh", true);
2985 VM_OBJECT_WLOCK(obj);
2987 if (pmap_page_wired_mappings(m) == 0)
2988 vm_page_set_invalid(m, poffset, presid);
2989 vfs_vmio_unwire(bp, m);
2993 VM_OBJECT_WUNLOCK(obj);
2998 * Page-granular truncation of an existing VMIO buffer.
3001 vfs_vmio_truncate(struct buf *bp, int desiredpages)
3007 if (bp->b_npages == desiredpages)
3010 if (buf_mapped(bp)) {
3011 BUF_CHECK_MAPPED(bp);
3012 pmap_qremove((vm_offset_t)trunc_page((vm_offset_t)bp->b_data) +
3013 (desiredpages << PAGE_SHIFT), bp->b_npages - desiredpages);
3015 BUF_CHECK_UNMAPPED(bp);
3018 * The object lock is needed only if we will attempt to free pages.
3020 obj = (bp->b_flags & B_DIRECT) != 0 ? bp->b_bufobj->bo_object : NULL;
3022 VM_OBJECT_WLOCK(obj);
3023 for (i = desiredpages; i < bp->b_npages; i++) {
3025 KASSERT(m != bogus_page, ("allocbuf: bogus page found"));
3026 bp->b_pages[i] = NULL;
3027 vfs_vmio_unwire(bp, m);
3030 VM_OBJECT_WUNLOCK(obj);
3031 bp->b_npages = desiredpages;
3035 * Byte granular extension of VMIO buffers.
3038 vfs_vmio_extend(struct buf *bp, int desiredpages, int size)
3041 * We are growing the buffer, possibly in a
3042 * byte-granular fashion.
3050 * Step 1, bring in the VM pages from the object, allocating
3051 * them if necessary. We must clear B_CACHE if these pages
3052 * are not valid for the range covered by the buffer.
3054 obj = bp->b_bufobj->bo_object;
3055 VM_OBJECT_WLOCK(obj);
3056 if (bp->b_npages < desiredpages) {
3058 * We must allocate system pages since blocking
3059 * here could interfere with paging I/O, no
3060 * matter which process we are.
3062 * Only exclusive busy can be tested here.
3063 * Blocking on shared busy might lead to
3064 * deadlocks once allocbuf() is called after
3065 * pages are vfs_busy_pages().
3067 (void)vm_page_grab_pages(obj,
3068 OFF_TO_IDX(bp->b_offset) + bp->b_npages,
3069 VM_ALLOC_SYSTEM | VM_ALLOC_IGN_SBUSY |
3070 VM_ALLOC_NOBUSY | VM_ALLOC_WIRED,
3071 &bp->b_pages[bp->b_npages], desiredpages - bp->b_npages);
3072 bp->b_npages = desiredpages;
3076 * Step 2. We've loaded the pages into the buffer,
3077 * we have to figure out if we can still have B_CACHE
3078 * set. Note that B_CACHE is set according to the
3079 * byte-granular range ( bcount and size ), not the
3080 * aligned range ( newbsize ).
3082 * The VM test is against m->valid, which is DEV_BSIZE
3083 * aligned. Needless to say, the validity of the data
3084 * needs to also be DEV_BSIZE aligned. Note that this
3085 * fails with NFS if the server or some other client
3086 * extends the file's EOF. If our buffer is resized,
3087 * B_CACHE may remain set! XXX
3089 toff = bp->b_bcount;
3090 tinc = PAGE_SIZE - ((bp->b_offset + toff) & PAGE_MASK);
3091 while ((bp->b_flags & B_CACHE) && toff < size) {
3094 if (tinc > (size - toff))
3096 pi = ((bp->b_offset & PAGE_MASK) + toff) >> PAGE_SHIFT;
3097 m = bp->b_pages[pi];
3098 vfs_buf_test_cache(bp, bp->b_offset, toff, tinc, m);
3102 VM_OBJECT_WUNLOCK(obj);
3105 * Step 3, fixup the KVA pmap.
3110 BUF_CHECK_UNMAPPED(bp);
3114 * Check to see if a block at a particular lbn is available for a clustered
3118 vfs_bio_clcheck(struct vnode *vp, int size, daddr_t lblkno, daddr_t blkno)
3125 /* If the buf isn't in core skip it */
3126 if ((bpa = gbincore(&vp->v_bufobj, lblkno)) == NULL)
3129 /* If the buf is busy we don't want to wait for it */
3130 if (BUF_LOCK(bpa, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0)
3133 /* Only cluster with valid clusterable delayed write buffers */
3134 if ((bpa->b_flags & (B_DELWRI | B_CLUSTEROK | B_INVAL)) !=
3135 (B_DELWRI | B_CLUSTEROK))
3138 if (bpa->b_bufsize != size)
3142 * Check to see if it is in the expected place on disk and that the
3143 * block has been mapped.
3145 if ((bpa->b_blkno != bpa->b_lblkno) && (bpa->b_blkno == blkno))
3155 * Implement clustered async writes for clearing out B_DELWRI buffers.
3156 * This is much better then the old way of writing only one buffer at
3157 * a time. Note that we may not be presented with the buffers in the
3158 * correct order, so we search for the cluster in both directions.
3161 vfs_bio_awrite(struct buf *bp)
3166 daddr_t lblkno = bp->b_lblkno;
3167 struct vnode *vp = bp->b_vp;
3175 gbflags = (bp->b_data == unmapped_buf) ? GB_UNMAPPED : 0;
3177 * right now we support clustered writing only to regular files. If
3178 * we find a clusterable block we could be in the middle of a cluster
3179 * rather then at the beginning.
3181 if ((vp->v_type == VREG) &&
3182 (vp->v_mount != 0) && /* Only on nodes that have the size info */
3183 (bp->b_flags & (B_CLUSTEROK | B_INVAL)) == B_CLUSTEROK) {
3185 size = vp->v_mount->mnt_stat.f_iosize;
3186 maxcl = MAXPHYS / size;
3189 for (i = 1; i < maxcl; i++)
3190 if (vfs_bio_clcheck(vp, size, lblkno + i,
3191 bp->b_blkno + ((i * size) >> DEV_BSHIFT)) == 0)
3194 for (j = 1; i + j <= maxcl && j <= lblkno; j++)
3195 if (vfs_bio_clcheck(vp, size, lblkno - j,
3196 bp->b_blkno - ((j * size) >> DEV_BSHIFT)) == 0)
3202 * this is a possible cluster write
3206 nwritten = cluster_wbuild(vp, size, lblkno - j, ncl,
3212 bp->b_flags |= B_ASYNC;
3214 * default (old) behavior, writing out only one block
3216 * XXX returns b_bufsize instead of b_bcount for nwritten?
3218 nwritten = bp->b_bufsize;
3227 * Allocate KVA for an empty buf header according to gbflags.
3230 getnewbuf_kva(struct buf *bp, int gbflags, int maxsize)
3233 if ((gbflags & (GB_UNMAPPED | GB_KVAALLOC)) != GB_UNMAPPED) {
3235 * In order to keep fragmentation sane we only allocate kva
3236 * in BKVASIZE chunks. XXX with vmem we can do page size.
3238 maxsize = (maxsize + BKVAMASK) & ~BKVAMASK;
3240 if (maxsize != bp->b_kvasize &&
3241 bufkva_alloc(bp, maxsize, gbflags))
3250 * Find and initialize a new buffer header, freeing up existing buffers
3251 * in the bufqueues as necessary. The new buffer is returned locked.
3254 * We have insufficient buffer headers
3255 * We have insufficient buffer space
3256 * buffer_arena is too fragmented ( space reservation fails )
3257 * If we have to flush dirty buffers ( but we try to avoid this )
3259 * The caller is responsible for releasing the reserved bufspace after
3260 * allocbuf() is called.
3263 getnewbuf(struct vnode *vp, int slpflag, int slptimeo, int maxsize, int gbflags)
3265 struct bufdomain *bd;
3267 bool metadata, reserved;
3270 KASSERT((gbflags & (GB_UNMAPPED | GB_KVAALLOC)) != GB_KVAALLOC,
3271 ("GB_KVAALLOC only makes sense with GB_UNMAPPED"));
3272 if (!unmapped_buf_allowed)
3273 gbflags &= ~(GB_UNMAPPED | GB_KVAALLOC);
3275 if (vp == NULL || (vp->v_vflag & (VV_MD | VV_SYSTEM)) != 0 ||
3283 bd = &bdomain[vp->v_bufobj.bo_domain];
3285 counter_u64_add(getnewbufcalls, 1);
3288 if (reserved == false &&
3289 bufspace_reserve(bd, maxsize, metadata) != 0) {
3290 counter_u64_add(getnewbufrestarts, 1);
3294 if ((bp = buf_alloc(bd)) == NULL) {
3295 counter_u64_add(getnewbufrestarts, 1);
3298 if (getnewbuf_kva(bp, gbflags, maxsize) == 0)
3301 } while (buf_recycle(bd, false) == 0);
3304 bufspace_release(bd, maxsize);
3306 bp->b_flags |= B_INVAL;
3309 bufspace_wait(bd, vp, gbflags, slpflag, slptimeo);
3317 * buffer flushing daemon. Buffers are normally flushed by the
3318 * update daemon but if it cannot keep up this process starts to
3319 * take the load in an attempt to prevent getnewbuf() from blocking.
3321 static struct kproc_desc buf_kp = {
3326 SYSINIT(bufdaemon, SI_SUB_KTHREAD_BUF, SI_ORDER_FIRST, kproc_start, &buf_kp);
3329 buf_flush(struct vnode *vp, struct bufdomain *bd, int target)
3333 flushed = flushbufqueues(vp, bd, target, 0);
3336 * Could not find any buffers without rollback
3337 * dependencies, so just write the first one
3338 * in the hopes of eventually making progress.
3340 if (vp != NULL && target > 2)
3342 flushbufqueues(vp, bd, target, 1);
3350 struct bufdomain *bd;
3356 * This process needs to be suspended prior to shutdown sync.
3358 EVENTHANDLER_REGISTER(shutdown_pre_sync, kthread_shutdown, curthread,
3359 SHUTDOWN_PRI_LAST + 100);
3362 * Start the buf clean daemons as children threads.
3364 for (i = 0 ; i < buf_domains; i++) {
3367 error = kthread_add((void (*)(void *))bufspace_daemon,
3368 &bdomain[i], curproc, NULL, 0, 0, "bufspacedaemon-%d", i);
3370 panic("error %d spawning bufspace daemon", error);
3374 * This process is allowed to take the buffer cache to the limit
3376 curthread->td_pflags |= TDP_NORUNNINGBUF | TDP_BUFNEED;
3380 mtx_unlock(&bdlock);
3382 kthread_suspend_check();
3385 * Save speedupreq for this pass and reset to capture new
3388 speedupreq = bd_speedupreq;
3392 * Flush each domain sequentially according to its level and
3393 * the speedup request.
3395 for (i = 0; i < buf_domains; i++) {
3398 lodirty = bd->bd_numdirtybuffers / 2;
3400 lodirty = bd->bd_lodirtybuffers;
3401 while (bd->bd_numdirtybuffers > lodirty) {
3402 if (buf_flush(NULL, bd,
3403 bd->bd_numdirtybuffers - lodirty) == 0)
3405 kern_yield(PRI_USER);
3410 * Only clear bd_request if we have reached our low water
3411 * mark. The buf_daemon normally waits 1 second and
3412 * then incrementally flushes any dirty buffers that have
3413 * built up, within reason.
3415 * If we were unable to hit our low water mark and couldn't
3416 * find any flushable buffers, we sleep for a short period
3417 * to avoid endless loops on unlockable buffers.
3420 if (!BIT_EMPTY(BUF_DOMAINS, &bdlodirty)) {
3422 * We reached our low water mark, reset the
3423 * request and sleep until we are needed again.
3424 * The sleep is just so the suspend code works.
3428 * Do an extra wakeup in case dirty threshold
3429 * changed via sysctl and the explicit transition
3430 * out of shortfall was missed.
3433 if (runningbufspace <= lorunningspace)
3435 msleep(&bd_request, &bdlock, PVM, "psleep", hz);
3438 * We couldn't find any flushable dirty buffers but
3439 * still have too many dirty buffers, we
3440 * have to sleep and try again. (rare)
3442 msleep(&bd_request, &bdlock, PVM, "qsleep", hz / 10);
3450 * Try to flush a buffer in the dirty queue. We must be careful to
3451 * free up B_INVAL buffers instead of write them, which NFS is
3452 * particularly sensitive to.
3454 static int flushwithdeps = 0;
3455 SYSCTL_INT(_vfs, OID_AUTO, flushwithdeps, CTLFLAG_RW, &flushwithdeps,
3456 0, "Number of buffers flushed with dependecies that require rollbacks");
3459 flushbufqueues(struct vnode *lvp, struct bufdomain *bd, int target,
3462 struct bufqueue *bq;
3463 struct buf *sentinel;
3473 bq = &bd->bd_dirtyq;
3475 sentinel = malloc(sizeof(struct buf), M_TEMP, M_WAITOK | M_ZERO);
3476 sentinel->b_qindex = QUEUE_SENTINEL;
3478 TAILQ_INSERT_HEAD(&bq->bq_queue, sentinel, b_freelist);
3480 while (flushed != target) {
3483 bp = TAILQ_NEXT(sentinel, b_freelist);
3485 TAILQ_REMOVE(&bq->bq_queue, sentinel, b_freelist);
3486 TAILQ_INSERT_AFTER(&bq->bq_queue, bp, sentinel,
3493 * Skip sentinels inserted by other invocations of the
3494 * flushbufqueues(), taking care to not reorder them.
3496 * Only flush the buffers that belong to the
3497 * vnode locked by the curthread.
3499 if (bp->b_qindex == QUEUE_SENTINEL || (lvp != NULL &&
3504 error = BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL);
3510 * BKGRDINPROG can only be set with the buf and bufobj
3511 * locks both held. We tolerate a race to clear it here.
3513 if ((bp->b_vflags & BV_BKGRDINPROG) != 0 ||
3514 (bp->b_flags & B_DELWRI) == 0) {
3518 if (bp->b_flags & B_INVAL) {
3525 if (!LIST_EMPTY(&bp->b_dep) && buf_countdeps(bp, 0)) {
3526 if (flushdeps == 0) {
3534 * We must hold the lock on a vnode before writing
3535 * one of its buffers. Otherwise we may confuse, or
3536 * in the case of a snapshot vnode, deadlock the
3539 * The lock order here is the reverse of the normal
3540 * of vnode followed by buf lock. This is ok because
3541 * the NOWAIT will prevent deadlock.
3544 if (vn_start_write(vp, &mp, V_NOWAIT) != 0) {
3550 error = vn_lock(vp, LK_EXCLUSIVE | LK_NOWAIT);
3552 ASSERT_VOP_LOCKED(vp, "getbuf");
3554 error = VOP_ISLOCKED(vp) == LK_EXCLUSIVE ? 0 :
3555 vn_lock(vp, LK_TRYUPGRADE);
3558 CTR3(KTR_BUF, "flushbufqueue(%p) vp %p flags %X",
3559 bp, bp->b_vp, bp->b_flags);
3560 if (curproc == bufdaemonproc) {
3565 counter_u64_add(notbufdflushes, 1);
3567 vn_finished_write(mp);
3570 flushwithdeps += hasdeps;
3574 * Sleeping on runningbufspace while holding
3575 * vnode lock leads to deadlock.
3577 if (curproc == bufdaemonproc &&
3578 runningbufspace > hirunningspace)
3579 waitrunningbufspace();
3582 vn_finished_write(mp);
3586 TAILQ_REMOVE(&bq->bq_queue, sentinel, b_freelist);
3588 free(sentinel, M_TEMP);
3593 * Check to see if a block is currently memory resident.
3596 incore(struct bufobj *bo, daddr_t blkno)
3601 bp = gbincore(bo, blkno);
3607 * Returns true if no I/O is needed to access the
3608 * associated VM object. This is like incore except
3609 * it also hunts around in the VM system for the data.
3613 inmem(struct vnode * vp, daddr_t blkno)
3616 vm_offset_t toff, tinc, size;
3620 ASSERT_VOP_LOCKED(vp, "inmem");
3622 if (incore(&vp->v_bufobj, blkno))
3624 if (vp->v_mount == NULL)
3631 if (size > vp->v_mount->mnt_stat.f_iosize)
3632 size = vp->v_mount->mnt_stat.f_iosize;
3633 off = (vm_ooffset_t)blkno * (vm_ooffset_t)vp->v_mount->mnt_stat.f_iosize;
3635 VM_OBJECT_RLOCK(obj);
3636 for (toff = 0; toff < vp->v_mount->mnt_stat.f_iosize; toff += tinc) {
3637 m = vm_page_lookup(obj, OFF_TO_IDX(off + toff));
3641 if (tinc > PAGE_SIZE - ((toff + off) & PAGE_MASK))
3642 tinc = PAGE_SIZE - ((toff + off) & PAGE_MASK);
3643 if (vm_page_is_valid(m,
3644 (vm_offset_t) ((toff + off) & PAGE_MASK), tinc) == 0)
3647 VM_OBJECT_RUNLOCK(obj);
3651 VM_OBJECT_RUNLOCK(obj);
3656 * Set the dirty range for a buffer based on the status of the dirty
3657 * bits in the pages comprising the buffer. The range is limited
3658 * to the size of the buffer.
3660 * Tell the VM system that the pages associated with this buffer
3661 * are clean. This is used for delayed writes where the data is
3662 * going to go to disk eventually without additional VM intevention.
3664 * Note that while we only really need to clean through to b_bcount, we
3665 * just go ahead and clean through to b_bufsize.
3668 vfs_clean_pages_dirty_buf(struct buf *bp)
3670 vm_ooffset_t foff, noff, eoff;
3674 if ((bp->b_flags & B_VMIO) == 0 || bp->b_bufsize == 0)
3677 foff = bp->b_offset;
3678 KASSERT(bp->b_offset != NOOFFSET,
3679 ("vfs_clean_pages_dirty_buf: no buffer offset"));
3681 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object);
3682 vfs_drain_busy_pages(bp);
3683 vfs_setdirty_locked_object(bp);
3684 for (i = 0; i < bp->b_npages; i++) {
3685 noff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK;
3687 if (eoff > bp->b_offset + bp->b_bufsize)
3688 eoff = bp->b_offset + bp->b_bufsize;
3690 vfs_page_set_validclean(bp, foff, m);
3691 /* vm_page_clear_dirty(m, foff & PAGE_MASK, eoff - foff); */
3694 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object);
3698 vfs_setdirty_locked_object(struct buf *bp)
3703 object = bp->b_bufobj->bo_object;
3704 VM_OBJECT_ASSERT_WLOCKED(object);
3707 * We qualify the scan for modified pages on whether the
3708 * object has been flushed yet.
3710 if ((object->flags & OBJ_MIGHTBEDIRTY) != 0) {
3711 vm_offset_t boffset;
3712 vm_offset_t eoffset;
3715 * test the pages to see if they have been modified directly
3716 * by users through the VM system.
3718 for (i = 0; i < bp->b_npages; i++)
3719 vm_page_test_dirty(bp->b_pages[i]);
3722 * Calculate the encompassing dirty range, boffset and eoffset,
3723 * (eoffset - boffset) bytes.
3726 for (i = 0; i < bp->b_npages; i++) {
3727 if (bp->b_pages[i]->dirty)
3730 boffset = (i << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK);
3732 for (i = bp->b_npages - 1; i >= 0; --i) {
3733 if (bp->b_pages[i]->dirty) {
3737 eoffset = ((i + 1) << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK);
3740 * Fit it to the buffer.
3743 if (eoffset > bp->b_bcount)
3744 eoffset = bp->b_bcount;
3747 * If we have a good dirty range, merge with the existing
3751 if (boffset < eoffset) {
3752 if (bp->b_dirtyoff > boffset)
3753 bp->b_dirtyoff = boffset;
3754 if (bp->b_dirtyend < eoffset)
3755 bp->b_dirtyend = eoffset;
3761 * Allocate the KVA mapping for an existing buffer.
3762 * If an unmapped buffer is provided but a mapped buffer is requested, take
3763 * also care to properly setup mappings between pages and KVA.
3766 bp_unmapped_get_kva(struct buf *bp, daddr_t blkno, int size, int gbflags)
3768 int bsize, maxsize, need_mapping, need_kva;
3771 need_mapping = bp->b_data == unmapped_buf &&
3772 (gbflags & GB_UNMAPPED) == 0;
3773 need_kva = bp->b_kvabase == unmapped_buf &&
3774 bp->b_data == unmapped_buf &&
3775 (gbflags & GB_KVAALLOC) != 0;
3776 if (!need_mapping && !need_kva)
3779 BUF_CHECK_UNMAPPED(bp);
3781 if (need_mapping && bp->b_kvabase != unmapped_buf) {
3783 * Buffer is not mapped, but the KVA was already
3784 * reserved at the time of the instantiation. Use the
3791 * Calculate the amount of the address space we would reserve
3792 * if the buffer was mapped.
3794 bsize = vn_isdisk(bp->b_vp, NULL) ? DEV_BSIZE : bp->b_bufobj->bo_bsize;
3795 KASSERT(bsize != 0, ("bsize == 0, check bo->bo_bsize"));
3796 offset = blkno * bsize;
3797 maxsize = size + (offset & PAGE_MASK);
3798 maxsize = imax(maxsize, bsize);
3800 while (bufkva_alloc(bp, maxsize, gbflags) != 0) {
3801 if ((gbflags & GB_NOWAIT_BD) != 0) {
3803 * XXXKIB: defragmentation cannot
3804 * succeed, not sure what else to do.
3806 panic("GB_NOWAIT_BD and GB_UNMAPPED %p", bp);
3808 counter_u64_add(mappingrestarts, 1);
3809 bufspace_wait(bufdomain(bp), bp->b_vp, gbflags, 0, 0);
3813 /* b_offset is handled by bpmap_qenter. */
3814 bp->b_data = bp->b_kvabase;
3815 BUF_CHECK_MAPPED(bp);
3821 getblk(struct vnode *vp, daddr_t blkno, int size, int slpflag, int slptimeo,
3827 error = getblkx(vp, blkno, size, slpflag, slptimeo, flags, &bp);
3836 * Get a block given a specified block and offset into a file/device.
3837 * The buffers B_DONE bit will be cleared on return, making it almost
3838 * ready for an I/O initiation. B_INVAL may or may not be set on
3839 * return. The caller should clear B_INVAL prior to initiating a
3842 * For a non-VMIO buffer, B_CACHE is set to the opposite of B_INVAL for
3843 * an existing buffer.
3845 * For a VMIO buffer, B_CACHE is modified according to the backing VM.
3846 * If getblk()ing a previously 0-sized invalid buffer, B_CACHE is set
3847 * and then cleared based on the backing VM. If the previous buffer is
3848 * non-0-sized but invalid, B_CACHE will be cleared.
3850 * If getblk() must create a new buffer, the new buffer is returned with
3851 * both B_INVAL and B_CACHE clear unless it is a VMIO buffer, in which
3852 * case it is returned with B_INVAL clear and B_CACHE set based on the
3855 * getblk() also forces a bwrite() for any B_DELWRI buffer whos
3856 * B_CACHE bit is clear.
3858 * What this means, basically, is that the caller should use B_CACHE to
3859 * determine whether the buffer is fully valid or not and should clear
3860 * B_INVAL prior to issuing a read. If the caller intends to validate
3861 * the buffer by loading its data area with something, the caller needs
3862 * to clear B_INVAL. If the caller does this without issuing an I/O,
3863 * the caller should set B_CACHE ( as an optimization ), else the caller
3864 * should issue the I/O and biodone() will set B_CACHE if the I/O was
3865 * a write attempt or if it was a successful read. If the caller
3866 * intends to issue a READ, the caller must clear B_INVAL and BIO_ERROR
3867 * prior to issuing the READ. biodone() will *not* clear B_INVAL.
3870 getblkx(struct vnode *vp, daddr_t blkno, int size, int slpflag, int slptimeo,
3871 int flags, struct buf **bpp)
3876 int bsize, error, maxsize, vmio;
3879 CTR3(KTR_BUF, "getblk(%p, %ld, %d)", vp, (long)blkno, size);
3880 KASSERT((flags & (GB_UNMAPPED | GB_KVAALLOC)) != GB_KVAALLOC,
3881 ("GB_KVAALLOC only makes sense with GB_UNMAPPED"));
3882 ASSERT_VOP_LOCKED(vp, "getblk");
3883 if (size > maxbcachebuf)
3884 panic("getblk: size(%d) > maxbcachebuf(%d)\n", size,
3886 if (!unmapped_buf_allowed)
3887 flags &= ~(GB_UNMAPPED | GB_KVAALLOC);
3893 bp = gbincore(bo, blkno);
3897 * Buffer is in-core. If the buffer is not busy nor managed,
3898 * it must be on a queue.
3900 lockflags = LK_EXCLUSIVE | LK_SLEEPFAIL | LK_INTERLOCK;
3902 if ((flags & GB_LOCK_NOWAIT) != 0)
3903 lockflags |= LK_NOWAIT;
3905 error = BUF_TIMELOCK(bp, lockflags,
3906 BO_LOCKPTR(bo), "getblk", slpflag, slptimeo);
3909 * If we slept and got the lock we have to restart in case
3910 * the buffer changed identities.
3912 if (error == ENOLCK)
3914 /* We timed out or were interrupted. */
3915 else if (error != 0)
3917 /* If recursed, assume caller knows the rules. */
3918 else if (BUF_LOCKRECURSED(bp))
3922 * The buffer is locked. B_CACHE is cleared if the buffer is
3923 * invalid. Otherwise, for a non-VMIO buffer, B_CACHE is set
3924 * and for a VMIO buffer B_CACHE is adjusted according to the
3927 if (bp->b_flags & B_INVAL)
3928 bp->b_flags &= ~B_CACHE;
3929 else if ((bp->b_flags & (B_VMIO | B_INVAL)) == 0)
3930 bp->b_flags |= B_CACHE;
3931 if (bp->b_flags & B_MANAGED)
3932 MPASS(bp->b_qindex == QUEUE_NONE);
3937 * check for size inconsistencies for non-VMIO case.
3939 if (bp->b_bcount != size) {
3940 if ((bp->b_flags & B_VMIO) == 0 ||
3941 (size > bp->b_kvasize)) {
3942 if (bp->b_flags & B_DELWRI) {
3943 bp->b_flags |= B_NOCACHE;
3946 if (LIST_EMPTY(&bp->b_dep)) {
3947 bp->b_flags |= B_RELBUF;
3950 bp->b_flags |= B_NOCACHE;
3959 * Handle the case of unmapped buffer which should
3960 * become mapped, or the buffer for which KVA
3961 * reservation is requested.
3963 bp_unmapped_get_kva(bp, blkno, size, flags);
3966 * If the size is inconsistent in the VMIO case, we can resize
3967 * the buffer. This might lead to B_CACHE getting set or
3968 * cleared. If the size has not changed, B_CACHE remains
3969 * unchanged from its previous state.
3973 KASSERT(bp->b_offset != NOOFFSET,
3974 ("getblk: no buffer offset"));
3977 * A buffer with B_DELWRI set and B_CACHE clear must
3978 * be committed before we can return the buffer in
3979 * order to prevent the caller from issuing a read
3980 * ( due to B_CACHE not being set ) and overwriting
3983 * Most callers, including NFS and FFS, need this to
3984 * operate properly either because they assume they
3985 * can issue a read if B_CACHE is not set, or because
3986 * ( for example ) an uncached B_DELWRI might loop due
3987 * to softupdates re-dirtying the buffer. In the latter
3988 * case, B_CACHE is set after the first write completes,
3989 * preventing further loops.
3990 * NOTE! b*write() sets B_CACHE. If we cleared B_CACHE
3991 * above while extending the buffer, we cannot allow the
3992 * buffer to remain with B_CACHE set after the write
3993 * completes or it will represent a corrupt state. To
3994 * deal with this we set B_NOCACHE to scrap the buffer
3997 * We might be able to do something fancy, like setting
3998 * B_CACHE in bwrite() except if B_DELWRI is already set,
3999 * so the below call doesn't set B_CACHE, but that gets real
4000 * confusing. This is much easier.
4003 if ((bp->b_flags & (B_CACHE|B_DELWRI)) == B_DELWRI) {
4004 bp->b_flags |= B_NOCACHE;
4008 bp->b_flags &= ~B_DONE;
4011 * Buffer is not in-core, create new buffer. The buffer
4012 * returned by getnewbuf() is locked. Note that the returned
4013 * buffer is also considered valid (not marked B_INVAL).
4017 * If the user does not want us to create the buffer, bail out
4020 if (flags & GB_NOCREAT)
4022 if (bdomain[bo->bo_domain].bd_freebuffers == 0 &&
4023 TD_IS_IDLETHREAD(curthread))
4026 bsize = vn_isdisk(vp, NULL) ? DEV_BSIZE : bo->bo_bsize;
4027 KASSERT(bsize != 0, ("bsize == 0, check bo->bo_bsize"));
4028 offset = blkno * bsize;
4029 vmio = vp->v_object != NULL;
4031 maxsize = size + (offset & PAGE_MASK);
4034 /* Do not allow non-VMIO notmapped buffers. */
4035 flags &= ~(GB_UNMAPPED | GB_KVAALLOC);
4037 maxsize = imax(maxsize, bsize);
4038 if ((flags & GB_NOSPARSE) != 0 && vmio &&
4039 !vn_isdisk(vp, NULL)) {
4040 error = VOP_BMAP(vp, blkno, NULL, &d_blkno, 0, 0);
4041 KASSERT(error != EOPNOTSUPP,
4042 ("GB_NOSPARSE from fs not supporting bmap, vp %p",
4047 return (EJUSTRETURN);
4050 bp = getnewbuf(vp, slpflag, slptimeo, maxsize, flags);
4052 if (slpflag || slptimeo)
4055 * XXX This is here until the sleep path is diagnosed
4056 * enough to work under very low memory conditions.
4058 * There's an issue on low memory, 4BSD+non-preempt
4059 * systems (eg MIPS routers with 32MB RAM) where buffer
4060 * exhaustion occurs without sleeping for buffer
4061 * reclaimation. This just sticks in a loop and
4062 * constantly attempts to allocate a buffer, which
4063 * hits exhaustion and tries to wakeup bufdaemon.
4064 * This never happens because we never yield.
4066 * The real solution is to identify and fix these cases
4067 * so we aren't effectively busy-waiting in a loop
4068 * until the reclaimation path has cycles to run.
4070 kern_yield(PRI_USER);
4075 * This code is used to make sure that a buffer is not
4076 * created while the getnewbuf routine is blocked.
4077 * This can be a problem whether the vnode is locked or not.
4078 * If the buffer is created out from under us, we have to
4079 * throw away the one we just created.
4081 * Note: this must occur before we associate the buffer
4082 * with the vp especially considering limitations in
4083 * the splay tree implementation when dealing with duplicate
4087 if (gbincore(bo, blkno)) {
4089 bp->b_flags |= B_INVAL;
4090 bufspace_release(bufdomain(bp), maxsize);
4096 * Insert the buffer into the hash, so that it can
4097 * be found by incore.
4099 bp->b_lblkno = blkno;
4100 bp->b_blkno = d_blkno;
4101 bp->b_offset = offset;
4106 * set B_VMIO bit. allocbuf() the buffer bigger. Since the
4107 * buffer size starts out as 0, B_CACHE will be set by
4108 * allocbuf() for the VMIO case prior to it testing the
4109 * backing store for validity.
4113 bp->b_flags |= B_VMIO;
4114 KASSERT(vp->v_object == bp->b_bufobj->bo_object,
4115 ("ARGH! different b_bufobj->bo_object %p %p %p\n",
4116 bp, vp->v_object, bp->b_bufobj->bo_object));
4118 bp->b_flags &= ~B_VMIO;
4119 KASSERT(bp->b_bufobj->bo_object == NULL,
4120 ("ARGH! has b_bufobj->bo_object %p %p\n",
4121 bp, bp->b_bufobj->bo_object));
4122 BUF_CHECK_MAPPED(bp);
4126 bufspace_release(bufdomain(bp), maxsize);
4127 bp->b_flags &= ~B_DONE;
4129 CTR4(KTR_BUF, "getblk(%p, %ld, %d) = %p", vp, (long)blkno, size, bp);
4130 BUF_ASSERT_HELD(bp);
4132 buf_track(bp, __func__);
4133 KASSERT(bp->b_bufobj == bo,
4134 ("bp %p wrong b_bufobj %p should be %p", bp, bp->b_bufobj, bo));
4140 * Get an empty, disassociated buffer of given size. The buffer is initially
4144 geteblk(int size, int flags)
4149 maxsize = (size + BKVAMASK) & ~BKVAMASK;
4150 while ((bp = getnewbuf(NULL, 0, 0, maxsize, flags)) == NULL) {
4151 if ((flags & GB_NOWAIT_BD) &&
4152 (curthread->td_pflags & TDP_BUFNEED) != 0)
4156 bufspace_release(bufdomain(bp), maxsize);
4157 bp->b_flags |= B_INVAL; /* b_dep cleared by getnewbuf() */
4158 BUF_ASSERT_HELD(bp);
4163 * Truncate the backing store for a non-vmio buffer.
4166 vfs_nonvmio_truncate(struct buf *bp, int newbsize)
4169 if (bp->b_flags & B_MALLOC) {
4171 * malloced buffers are not shrunk
4173 if (newbsize == 0) {
4174 bufmallocadjust(bp, 0);
4175 free(bp->b_data, M_BIOBUF);
4176 bp->b_data = bp->b_kvabase;
4177 bp->b_flags &= ~B_MALLOC;
4181 vm_hold_free_pages(bp, newbsize);
4182 bufspace_adjust(bp, newbsize);
4186 * Extend the backing for a non-VMIO buffer.
4189 vfs_nonvmio_extend(struct buf *bp, int newbsize)
4195 * We only use malloced memory on the first allocation.
4196 * and revert to page-allocated memory when the buffer
4199 * There is a potential smp race here that could lead
4200 * to bufmallocspace slightly passing the max. It
4201 * is probably extremely rare and not worth worrying
4204 if (bp->b_bufsize == 0 && newbsize <= PAGE_SIZE/2 &&
4205 bufmallocspace < maxbufmallocspace) {
4206 bp->b_data = malloc(newbsize, M_BIOBUF, M_WAITOK);
4207 bp->b_flags |= B_MALLOC;
4208 bufmallocadjust(bp, newbsize);
4213 * If the buffer is growing on its other-than-first
4214 * allocation then we revert to the page-allocation
4219 if (bp->b_flags & B_MALLOC) {
4220 origbuf = bp->b_data;
4221 origbufsize = bp->b_bufsize;
4222 bp->b_data = bp->b_kvabase;
4223 bufmallocadjust(bp, 0);
4224 bp->b_flags &= ~B_MALLOC;
4225 newbsize = round_page(newbsize);
4227 vm_hold_load_pages(bp, (vm_offset_t) bp->b_data + bp->b_bufsize,
4228 (vm_offset_t) bp->b_data + newbsize);
4229 if (origbuf != NULL) {
4230 bcopy(origbuf, bp->b_data, origbufsize);
4231 free(origbuf, M_BIOBUF);
4233 bufspace_adjust(bp, newbsize);
4237 * This code constitutes the buffer memory from either anonymous system
4238 * memory (in the case of non-VMIO operations) or from an associated
4239 * VM object (in the case of VMIO operations). This code is able to
4240 * resize a buffer up or down.
4242 * Note that this code is tricky, and has many complications to resolve
4243 * deadlock or inconsistent data situations. Tread lightly!!!
4244 * There are B_CACHE and B_DELWRI interactions that must be dealt with by
4245 * the caller. Calling this code willy nilly can result in the loss of data.
4247 * allocbuf() only adjusts B_CACHE for VMIO buffers. getblk() deals with
4248 * B_CACHE for the non-VMIO case.
4251 allocbuf(struct buf *bp, int size)
4255 BUF_ASSERT_HELD(bp);
4257 if (bp->b_bcount == size)
4260 if (bp->b_kvasize != 0 && bp->b_kvasize < size)
4261 panic("allocbuf: buffer too small");
4263 newbsize = roundup2(size, DEV_BSIZE);
4264 if ((bp->b_flags & B_VMIO) == 0) {
4265 if ((bp->b_flags & B_MALLOC) == 0)
4266 newbsize = round_page(newbsize);
4268 * Just get anonymous memory from the kernel. Don't
4269 * mess with B_CACHE.
4271 if (newbsize < bp->b_bufsize)
4272 vfs_nonvmio_truncate(bp, newbsize);
4273 else if (newbsize > bp->b_bufsize)
4274 vfs_nonvmio_extend(bp, newbsize);
4278 desiredpages = (size == 0) ? 0 :
4279 num_pages((bp->b_offset & PAGE_MASK) + newbsize);
4281 if (bp->b_flags & B_MALLOC)
4282 panic("allocbuf: VMIO buffer can't be malloced");
4284 * Set B_CACHE initially if buffer is 0 length or will become
4287 if (size == 0 || bp->b_bufsize == 0)
4288 bp->b_flags |= B_CACHE;
4290 if (newbsize < bp->b_bufsize)
4291 vfs_vmio_truncate(bp, desiredpages);
4292 /* XXX This looks as if it should be newbsize > b_bufsize */
4293 else if (size > bp->b_bcount)
4294 vfs_vmio_extend(bp, desiredpages, size);
4295 bufspace_adjust(bp, newbsize);
4297 bp->b_bcount = size; /* requested buffer size. */
4301 extern int inflight_transient_maps;
4303 static struct bio_queue nondump_bios;
4306 biodone(struct bio *bp)
4309 void (*done)(struct bio *);
4310 vm_offset_t start, end;
4312 biotrack(bp, __func__);
4315 * Avoid completing I/O when dumping after a panic since that may
4316 * result in a deadlock in the filesystem or pager code. Note that
4317 * this doesn't affect dumps that were started manually since we aim
4318 * to keep the system usable after it has been resumed.
4320 if (__predict_false(dumping && SCHEDULER_STOPPED())) {
4321 TAILQ_INSERT_HEAD(&nondump_bios, bp, bio_queue);
4324 if ((bp->bio_flags & BIO_TRANSIENT_MAPPING) != 0) {
4325 bp->bio_flags &= ~BIO_TRANSIENT_MAPPING;
4326 bp->bio_flags |= BIO_UNMAPPED;
4327 start = trunc_page((vm_offset_t)bp->bio_data);
4328 end = round_page((vm_offset_t)bp->bio_data + bp->bio_length);
4329 bp->bio_data = unmapped_buf;
4330 pmap_qremove(start, atop(end - start));
4331 vmem_free(transient_arena, start, end - start);
4332 atomic_add_int(&inflight_transient_maps, -1);
4334 done = bp->bio_done;
4336 mtxp = mtx_pool_find(mtxpool_sleep, bp);
4338 bp->bio_flags |= BIO_DONE;
4346 * Wait for a BIO to finish.
4349 biowait(struct bio *bp, const char *wchan)
4353 mtxp = mtx_pool_find(mtxpool_sleep, bp);
4355 while ((bp->bio_flags & BIO_DONE) == 0)
4356 msleep(bp, mtxp, PRIBIO, wchan, 0);
4358 if (bp->bio_error != 0)
4359 return (bp->bio_error);
4360 if (!(bp->bio_flags & BIO_ERROR))
4366 biofinish(struct bio *bp, struct devstat *stat, int error)
4370 bp->bio_error = error;
4371 bp->bio_flags |= BIO_ERROR;
4374 devstat_end_transaction_bio(stat, bp);
4378 #if defined(BUF_TRACKING) || defined(FULL_BUF_TRACKING)
4380 biotrack_buf(struct bio *bp, const char *location)
4383 buf_track(bp->bio_track_bp, location);
4390 * Wait for buffer I/O completion, returning error status. The buffer
4391 * is left locked and B_DONE on return. B_EINTR is converted into an EINTR
4392 * error and cleared.
4395 bufwait(struct buf *bp)
4397 if (bp->b_iocmd == BIO_READ)
4398 bwait(bp, PRIBIO, "biord");
4400 bwait(bp, PRIBIO, "biowr");
4401 if (bp->b_flags & B_EINTR) {
4402 bp->b_flags &= ~B_EINTR;
4405 if (bp->b_ioflags & BIO_ERROR) {
4406 return (bp->b_error ? bp->b_error : EIO);
4415 * Finish I/O on a buffer, optionally calling a completion function.
4416 * This is usually called from an interrupt so process blocking is
4419 * biodone is also responsible for setting B_CACHE in a B_VMIO bp.
4420 * In a non-VMIO bp, B_CACHE will be set on the next getblk()
4421 * assuming B_INVAL is clear.
4423 * For the VMIO case, we set B_CACHE if the op was a read and no
4424 * read error occurred, or if the op was a write. B_CACHE is never
4425 * set if the buffer is invalid or otherwise uncacheable.
4427 * biodone does not mess with B_INVAL, allowing the I/O routine or the
4428 * initiator to leave B_INVAL set to brelse the buffer out of existence
4429 * in the biodone routine.
4432 bufdone(struct buf *bp)
4434 struct bufobj *dropobj;
4435 void (*biodone)(struct buf *);
4437 buf_track(bp, __func__);
4438 CTR3(KTR_BUF, "bufdone(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
4441 KASSERT(!(bp->b_flags & B_DONE), ("biodone: bp %p already done", bp));
4442 BUF_ASSERT_HELD(bp);
4444 runningbufwakeup(bp);
4445 if (bp->b_iocmd == BIO_WRITE)
4446 dropobj = bp->b_bufobj;
4447 /* call optional completion function if requested */
4448 if (bp->b_iodone != NULL) {
4449 biodone = bp->b_iodone;
4450 bp->b_iodone = NULL;
4453 bufobj_wdrop(dropobj);
4456 if (bp->b_flags & B_VMIO) {
4458 * Set B_CACHE if the op was a normal read and no error
4459 * occurred. B_CACHE is set for writes in the b*write()
4462 if (bp->b_iocmd == BIO_READ &&
4463 !(bp->b_flags & (B_INVAL|B_NOCACHE)) &&
4464 !(bp->b_ioflags & BIO_ERROR))
4465 bp->b_flags |= B_CACHE;
4466 vfs_vmio_iodone(bp);
4468 if (!LIST_EMPTY(&bp->b_dep))
4470 if ((bp->b_flags & B_CKHASH) != 0) {
4471 KASSERT(bp->b_iocmd == BIO_READ,
4472 ("bufdone: b_iocmd %d not BIO_READ", bp->b_iocmd));
4473 KASSERT(buf_mapped(bp), ("bufdone: bp %p not mapped", bp));
4474 (*bp->b_ckhashcalc)(bp);
4477 * For asynchronous completions, release the buffer now. The brelse
4478 * will do a wakeup there if necessary - so no need to do a wakeup
4479 * here in the async case. The sync case always needs to do a wakeup.
4481 if (bp->b_flags & B_ASYNC) {
4482 if ((bp->b_flags & (B_NOCACHE | B_INVAL | B_RELBUF)) ||
4483 (bp->b_ioflags & BIO_ERROR))
4490 bufobj_wdrop(dropobj);
4494 * This routine is called in lieu of iodone in the case of
4495 * incomplete I/O. This keeps the busy status for pages
4499 vfs_unbusy_pages(struct buf *bp)
4505 runningbufwakeup(bp);
4506 if (!(bp->b_flags & B_VMIO))
4509 obj = bp->b_bufobj->bo_object;
4510 VM_OBJECT_WLOCK(obj);
4511 for (i = 0; i < bp->b_npages; i++) {
4513 if (m == bogus_page) {
4514 m = vm_page_lookup(obj, OFF_TO_IDX(bp->b_offset) + i);
4516 panic("vfs_unbusy_pages: page missing\n");
4518 if (buf_mapped(bp)) {
4519 BUF_CHECK_MAPPED(bp);
4520 pmap_qenter(trunc_page((vm_offset_t)bp->b_data),
4521 bp->b_pages, bp->b_npages);
4523 BUF_CHECK_UNMAPPED(bp);
4527 vm_object_pip_wakeupn(obj, bp->b_npages);
4528 VM_OBJECT_WUNLOCK(obj);
4532 * vfs_page_set_valid:
4534 * Set the valid bits in a page based on the supplied offset. The
4535 * range is restricted to the buffer's size.
4537 * This routine is typically called after a read completes.
4540 vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, vm_page_t m)
4545 * Compute the end offset, eoff, such that [off, eoff) does not span a
4546 * page boundary and eoff is not greater than the end of the buffer.
4547 * The end of the buffer, in this case, is our file EOF, not the
4548 * allocation size of the buffer.
4550 eoff = (off + PAGE_SIZE) & ~(vm_ooffset_t)PAGE_MASK;
4551 if (eoff > bp->b_offset + bp->b_bcount)
4552 eoff = bp->b_offset + bp->b_bcount;
4555 * Set valid range. This is typically the entire buffer and thus the
4559 vm_page_set_valid_range(m, off & PAGE_MASK, eoff - off);
4563 * vfs_page_set_validclean:
4565 * Set the valid bits and clear the dirty bits in a page based on the
4566 * supplied offset. The range is restricted to the buffer's size.
4569 vfs_page_set_validclean(struct buf *bp, vm_ooffset_t off, vm_page_t m)
4571 vm_ooffset_t soff, eoff;
4574 * Start and end offsets in buffer. eoff - soff may not cross a
4575 * page boundary or cross the end of the buffer. The end of the
4576 * buffer, in this case, is our file EOF, not the allocation size
4580 eoff = (off + PAGE_SIZE) & ~(off_t)PAGE_MASK;
4581 if (eoff > bp->b_offset + bp->b_bcount)
4582 eoff = bp->b_offset + bp->b_bcount;
4585 * Set valid range. This is typically the entire buffer and thus the
4589 vm_page_set_validclean(
4591 (vm_offset_t) (soff & PAGE_MASK),
4592 (vm_offset_t) (eoff - soff)
4598 * Ensure that all buffer pages are not exclusive busied. If any page is
4599 * exclusive busy, drain it.
4602 vfs_drain_busy_pages(struct buf *bp)
4607 VM_OBJECT_ASSERT_WLOCKED(bp->b_bufobj->bo_object);
4609 for (i = 0; i < bp->b_npages; i++) {
4611 if (vm_page_xbusied(m)) {
4612 for (; last_busied < i; last_busied++)
4613 vm_page_sbusy(bp->b_pages[last_busied]);
4614 while (vm_page_xbusied(m)) {
4616 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object);
4617 vm_page_busy_sleep(m, "vbpage", true);
4618 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object);
4622 for (i = 0; i < last_busied; i++)
4623 vm_page_sunbusy(bp->b_pages[i]);
4627 * This routine is called before a device strategy routine.
4628 * It is used to tell the VM system that paging I/O is in
4629 * progress, and treat the pages associated with the buffer
4630 * almost as being exclusive busy. Also the object paging_in_progress
4631 * flag is handled to make sure that the object doesn't become
4634 * Since I/O has not been initiated yet, certain buffer flags
4635 * such as BIO_ERROR or B_INVAL may be in an inconsistent state
4636 * and should be ignored.
4639 vfs_busy_pages(struct buf *bp, int clear_modify)
4647 if (!(bp->b_flags & B_VMIO))
4650 obj = bp->b_bufobj->bo_object;
4651 foff = bp->b_offset;
4652 KASSERT(bp->b_offset != NOOFFSET,
4653 ("vfs_busy_pages: no buffer offset"));
4654 VM_OBJECT_WLOCK(obj);
4655 vfs_drain_busy_pages(bp);
4656 if (bp->b_bufsize != 0)
4657 vfs_setdirty_locked_object(bp);
4659 for (i = 0; i < bp->b_npages; i++) {
4662 if ((bp->b_flags & B_CLUSTER) == 0) {
4663 vm_object_pip_add(obj, 1);
4667 * When readying a buffer for a read ( i.e
4668 * clear_modify == 0 ), it is important to do
4669 * bogus_page replacement for valid pages in
4670 * partially instantiated buffers. Partially
4671 * instantiated buffers can, in turn, occur when
4672 * reconstituting a buffer from its VM backing store
4673 * base. We only have to do this if B_CACHE is
4674 * clear ( which causes the I/O to occur in the
4675 * first place ). The replacement prevents the read
4676 * I/O from overwriting potentially dirty VM-backed
4677 * pages. XXX bogus page replacement is, uh, bogus.
4678 * It may not work properly with small-block devices.
4679 * We need to find a better way.
4682 pmap_remove_write(m);
4683 vfs_page_set_validclean(bp, foff, m);
4684 } else if (m->valid == VM_PAGE_BITS_ALL &&
4685 (bp->b_flags & B_CACHE) == 0) {
4686 bp->b_pages[i] = bogus_page;
4689 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK;
4691 VM_OBJECT_WUNLOCK(obj);
4692 if (bogus && buf_mapped(bp)) {
4693 BUF_CHECK_MAPPED(bp);
4694 pmap_qenter(trunc_page((vm_offset_t)bp->b_data),
4695 bp->b_pages, bp->b_npages);
4700 * vfs_bio_set_valid:
4702 * Set the range within the buffer to valid. The range is
4703 * relative to the beginning of the buffer, b_offset. Note that
4704 * b_offset itself may be offset from the beginning of the first
4708 vfs_bio_set_valid(struct buf *bp, int base, int size)
4713 if (!(bp->b_flags & B_VMIO))
4717 * Fixup base to be relative to beginning of first page.
4718 * Set initial n to be the maximum number of bytes in the
4719 * first page that can be validated.
4721 base += (bp->b_offset & PAGE_MASK);
4722 n = PAGE_SIZE - (base & PAGE_MASK);
4724 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object);
4725 for (i = base / PAGE_SIZE; size > 0 && i < bp->b_npages; ++i) {
4729 vm_page_set_valid_range(m, base & PAGE_MASK, n);
4734 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object);
4740 * If the specified buffer is a non-VMIO buffer, clear the entire
4741 * buffer. If the specified buffer is a VMIO buffer, clear and
4742 * validate only the previously invalid portions of the buffer.
4743 * This routine essentially fakes an I/O, so we need to clear
4744 * BIO_ERROR and B_INVAL.
4746 * Note that while we only theoretically need to clear through b_bcount,
4747 * we go ahead and clear through b_bufsize.
4750 vfs_bio_clrbuf(struct buf *bp)
4752 int i, j, mask, sa, ea, slide;
4754 if ((bp->b_flags & (B_VMIO | B_MALLOC)) != B_VMIO) {
4758 bp->b_flags &= ~B_INVAL;
4759 bp->b_ioflags &= ~BIO_ERROR;
4760 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object);
4761 if ((bp->b_npages == 1) && (bp->b_bufsize < PAGE_SIZE) &&
4762 (bp->b_offset & PAGE_MASK) == 0) {
4763 if (bp->b_pages[0] == bogus_page)
4765 mask = (1 << (bp->b_bufsize / DEV_BSIZE)) - 1;
4766 VM_OBJECT_ASSERT_WLOCKED(bp->b_pages[0]->object);
4767 if ((bp->b_pages[0]->valid & mask) == mask)
4769 if ((bp->b_pages[0]->valid & mask) == 0) {
4770 pmap_zero_page_area(bp->b_pages[0], 0, bp->b_bufsize);
4771 bp->b_pages[0]->valid |= mask;
4775 sa = bp->b_offset & PAGE_MASK;
4777 for (i = 0; i < bp->b_npages; i++, sa = 0) {
4778 slide = imin(slide + PAGE_SIZE, bp->b_offset + bp->b_bufsize);
4779 ea = slide & PAGE_MASK;
4782 if (bp->b_pages[i] == bogus_page)
4785 mask = ((1 << ((ea - sa) / DEV_BSIZE)) - 1) << j;
4786 VM_OBJECT_ASSERT_WLOCKED(bp->b_pages[i]->object);
4787 if ((bp->b_pages[i]->valid & mask) == mask)
4789 if ((bp->b_pages[i]->valid & mask) == 0)
4790 pmap_zero_page_area(bp->b_pages[i], sa, ea - sa);
4792 for (; sa < ea; sa += DEV_BSIZE, j++) {
4793 if ((bp->b_pages[i]->valid & (1 << j)) == 0) {
4794 pmap_zero_page_area(bp->b_pages[i],
4799 bp->b_pages[i]->valid |= mask;
4802 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object);
4807 vfs_bio_bzero_buf(struct buf *bp, int base, int size)
4812 if (buf_mapped(bp)) {
4813 BUF_CHECK_MAPPED(bp);
4814 bzero(bp->b_data + base, size);
4816 BUF_CHECK_UNMAPPED(bp);
4817 n = PAGE_SIZE - (base & PAGE_MASK);
4818 for (i = base / PAGE_SIZE; size > 0 && i < bp->b_npages; ++i) {
4822 pmap_zero_page_area(m, base & PAGE_MASK, n);
4831 * Update buffer flags based on I/O request parameters, optionally releasing the
4832 * buffer. If it's VMIO or direct I/O, the buffer pages are released to the VM,
4833 * where they may be placed on a page queue (VMIO) or freed immediately (direct
4834 * I/O). Otherwise the buffer is released to the cache.
4837 b_io_dismiss(struct buf *bp, int ioflag, bool release)
4840 KASSERT((ioflag & IO_NOREUSE) == 0 || (ioflag & IO_VMIO) != 0,
4841 ("buf %p non-VMIO noreuse", bp));
4843 if ((ioflag & IO_DIRECT) != 0)
4844 bp->b_flags |= B_DIRECT;
4845 if ((ioflag & IO_EXT) != 0)
4846 bp->b_xflags |= BX_ALTDATA;
4847 if ((ioflag & (IO_VMIO | IO_DIRECT)) != 0 && LIST_EMPTY(&bp->b_dep)) {
4848 bp->b_flags |= B_RELBUF;
4849 if ((ioflag & IO_NOREUSE) != 0)
4850 bp->b_flags |= B_NOREUSE;
4858 vfs_bio_brelse(struct buf *bp, int ioflag)
4861 b_io_dismiss(bp, ioflag, true);
4865 vfs_bio_set_flags(struct buf *bp, int ioflag)
4868 b_io_dismiss(bp, ioflag, false);
4872 * vm_hold_load_pages and vm_hold_free_pages get pages into
4873 * a buffers address space. The pages are anonymous and are
4874 * not associated with a file object.
4877 vm_hold_load_pages(struct buf *bp, vm_offset_t from, vm_offset_t to)
4883 BUF_CHECK_MAPPED(bp);
4885 to = round_page(to);
4886 from = round_page(from);
4887 index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT;
4889 for (pg = from; pg < to; pg += PAGE_SIZE, index++) {
4891 * note: must allocate system pages since blocking here
4892 * could interfere with paging I/O, no matter which
4895 p = vm_page_alloc(NULL, 0, VM_ALLOC_SYSTEM | VM_ALLOC_NOOBJ |
4896 VM_ALLOC_WIRED | VM_ALLOC_COUNT((to - pg) >> PAGE_SHIFT) |
4898 pmap_qenter(pg, &p, 1);
4899 bp->b_pages[index] = p;
4901 bp->b_npages = index;
4904 /* Return pages associated with this buf to the vm system */
4906 vm_hold_free_pages(struct buf *bp, int newbsize)
4910 int index, newnpages;
4912 BUF_CHECK_MAPPED(bp);
4914 from = round_page((vm_offset_t)bp->b_data + newbsize);
4915 newnpages = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT;
4916 if (bp->b_npages > newnpages)
4917 pmap_qremove(from, bp->b_npages - newnpages);
4918 for (index = newnpages; index < bp->b_npages; index++) {
4919 p = bp->b_pages[index];
4920 bp->b_pages[index] = NULL;
4924 vm_wire_sub(bp->b_npages - newnpages);
4925 bp->b_npages = newnpages;
4929 * Map an IO request into kernel virtual address space.
4931 * All requests are (re)mapped into kernel VA space.
4932 * Notice that we use b_bufsize for the size of the buffer
4933 * to be mapped. b_bcount might be modified by the driver.
4935 * Note that even if the caller determines that the address space should
4936 * be valid, a race or a smaller-file mapped into a larger space may
4937 * actually cause vmapbuf() to fail, so all callers of vmapbuf() MUST
4938 * check the return value.
4940 * This function only works with pager buffers.
4943 vmapbuf(struct buf *bp, int mapbuf)
4948 if (bp->b_bufsize < 0)
4950 prot = VM_PROT_READ;
4951 if (bp->b_iocmd == BIO_READ)
4952 prot |= VM_PROT_WRITE; /* Less backwards than it looks */
4953 if ((pidx = vm_fault_quick_hold_pages(&curproc->p_vmspace->vm_map,
4954 (vm_offset_t)bp->b_data, bp->b_bufsize, prot, bp->b_pages,
4955 btoc(MAXPHYS))) < 0)
4957 bp->b_npages = pidx;
4958 bp->b_offset = ((vm_offset_t)bp->b_data) & PAGE_MASK;
4959 if (mapbuf || !unmapped_buf_allowed) {
4960 pmap_qenter((vm_offset_t)bp->b_kvabase, bp->b_pages, pidx);
4961 bp->b_data = bp->b_kvabase + bp->b_offset;
4963 bp->b_data = unmapped_buf;
4968 * Free the io map PTEs associated with this IO operation.
4969 * We also invalidate the TLB entries and restore the original b_addr.
4971 * This function only works with pager buffers.
4974 vunmapbuf(struct buf *bp)
4978 npages = bp->b_npages;
4980 pmap_qremove(trunc_page((vm_offset_t)bp->b_data), npages);
4981 vm_page_unhold_pages(bp->b_pages, npages);
4983 bp->b_data = unmapped_buf;
4987 bdone(struct buf *bp)
4991 mtxp = mtx_pool_find(mtxpool_sleep, bp);
4993 bp->b_flags |= B_DONE;
4999 bwait(struct buf *bp, u_char pri, const char *wchan)
5003 mtxp = mtx_pool_find(mtxpool_sleep, bp);
5005 while ((bp->b_flags & B_DONE) == 0)
5006 msleep(bp, mtxp, pri, wchan, 0);
5011 bufsync(struct bufobj *bo, int waitfor)
5014 return (VOP_FSYNC(bo2vnode(bo), waitfor, curthread));
5018 bufstrategy(struct bufobj *bo, struct buf *bp)
5024 KASSERT(vp == bo->bo_private, ("Inconsistent vnode bufstrategy"));
5025 KASSERT(vp->v_type != VCHR && vp->v_type != VBLK,
5026 ("Wrong vnode in bufstrategy(bp=%p, vp=%p)", bp, vp));
5027 i = VOP_STRATEGY(vp, bp);
5028 KASSERT(i == 0, ("VOP_STRATEGY failed bp=%p vp=%p", bp, bp->b_vp));
5032 * Initialize a struct bufobj before use. Memory is assumed zero filled.
5035 bufobj_init(struct bufobj *bo, void *private)
5037 static volatile int bufobj_cleanq;
5040 atomic_fetchadd_int(&bufobj_cleanq, 1) % buf_domains;
5041 rw_init(BO_LOCKPTR(bo), "bufobj interlock");
5042 bo->bo_private = private;
5043 TAILQ_INIT(&bo->bo_clean.bv_hd);
5044 TAILQ_INIT(&bo->bo_dirty.bv_hd);
5048 bufobj_wrefl(struct bufobj *bo)
5051 KASSERT(bo != NULL, ("NULL bo in bufobj_wref"));
5052 ASSERT_BO_WLOCKED(bo);
5057 bufobj_wref(struct bufobj *bo)
5060 KASSERT(bo != NULL, ("NULL bo in bufobj_wref"));
5067 bufobj_wdrop(struct bufobj *bo)
5070 KASSERT(bo != NULL, ("NULL bo in bufobj_wdrop"));
5072 KASSERT(bo->bo_numoutput > 0, ("bufobj_wdrop non-positive count"));
5073 if ((--bo->bo_numoutput == 0) && (bo->bo_flag & BO_WWAIT)) {
5074 bo->bo_flag &= ~BO_WWAIT;
5075 wakeup(&bo->bo_numoutput);
5081 bufobj_wwait(struct bufobj *bo, int slpflag, int timeo)
5085 KASSERT(bo != NULL, ("NULL bo in bufobj_wwait"));
5086 ASSERT_BO_WLOCKED(bo);
5088 while (bo->bo_numoutput) {
5089 bo->bo_flag |= BO_WWAIT;
5090 error = msleep(&bo->bo_numoutput, BO_LOCKPTR(bo),
5091 slpflag | (PRIBIO + 1), "bo_wwait", timeo);
5099 * Set bio_data or bio_ma for struct bio from the struct buf.
5102 bdata2bio(struct buf *bp, struct bio *bip)
5105 if (!buf_mapped(bp)) {
5106 KASSERT(unmapped_buf_allowed, ("unmapped"));
5107 bip->bio_ma = bp->b_pages;
5108 bip->bio_ma_n = bp->b_npages;
5109 bip->bio_data = unmapped_buf;
5110 bip->bio_ma_offset = (vm_offset_t)bp->b_offset & PAGE_MASK;
5111 bip->bio_flags |= BIO_UNMAPPED;
5112 KASSERT(round_page(bip->bio_ma_offset + bip->bio_length) /
5113 PAGE_SIZE == bp->b_npages,
5114 ("Buffer %p too short: %d %lld %d", bp, bip->bio_ma_offset,
5115 (long long)bip->bio_length, bip->bio_ma_n));
5117 bip->bio_data = bp->b_data;
5123 * The MIPS pmap code currently doesn't handle aliased pages.
5124 * The VIPT caches may not handle page aliasing themselves, leading
5125 * to data corruption.
5127 * As such, this code makes a system extremely unhappy if said
5128 * system doesn't support unaliasing the above situation in hardware.
5129 * Some "recent" systems (eg some mips24k/mips74k cores) don't enable
5130 * this feature at build time, so it has to be handled in software.
5132 * Once the MIPS pmap/cache code grows to support this function on
5133 * earlier chips, it should be flipped back off.
5136 static int buf_pager_relbuf = 1;
5138 static int buf_pager_relbuf = 0;
5140 SYSCTL_INT(_vfs, OID_AUTO, buf_pager_relbuf, CTLFLAG_RWTUN,
5141 &buf_pager_relbuf, 0,
5142 "Make buffer pager release buffers after reading");
5145 * The buffer pager. It uses buffer reads to validate pages.
5147 * In contrast to the generic local pager from vm/vnode_pager.c, this
5148 * pager correctly and easily handles volumes where the underlying
5149 * device block size is greater than the machine page size. The
5150 * buffer cache transparently extends the requested page run to be
5151 * aligned at the block boundary, and does the necessary bogus page
5152 * replacements in the addends to avoid obliterating already valid
5155 * The only non-trivial issue is that the exclusive busy state for
5156 * pages, which is assumed by the vm_pager_getpages() interface, is
5157 * incompatible with the VMIO buffer cache's desire to share-busy the
5158 * pages. This function performs a trivial downgrade of the pages'
5159 * state before reading buffers, and a less trivial upgrade from the
5160 * shared-busy to excl-busy state after the read.
5163 vfs_bio_getpages(struct vnode *vp, vm_page_t *ma, int count,
5164 int *rbehind, int *rahead, vbg_get_lblkno_t get_lblkno,
5165 vbg_get_blksize_t get_blksize)
5172 vm_ooffset_t la, lb, poff, poffe;
5174 int bo_bs, br_flags, error, i, pgsin, pgsin_a, pgsin_b;
5177 object = vp->v_object;
5180 la = IDX_TO_OFF(ma[count - 1]->pindex);
5181 if (la >= object->un_pager.vnp.vnp_size)
5182 return (VM_PAGER_BAD);
5185 * Change the meaning of la from where the last requested page starts
5186 * to where it ends, because that's the end of the requested region
5187 * and the start of the potential read-ahead region.
5190 lpart = la > object->un_pager.vnp.vnp_size;
5191 bo_bs = get_blksize(vp, get_lblkno(vp, IDX_TO_OFF(ma[0]->pindex)));
5194 * Calculate read-ahead, behind and total pages.
5197 lb = IDX_TO_OFF(ma[0]->pindex);
5198 pgsin_b = OFF_TO_IDX(lb - rounddown2(lb, bo_bs));
5200 if (rbehind != NULL)
5202 pgsin_a = OFF_TO_IDX(roundup2(la, bo_bs) - la);
5203 if (la + IDX_TO_OFF(pgsin_a) >= object->un_pager.vnp.vnp_size)
5204 pgsin_a = OFF_TO_IDX(roundup2(object->un_pager.vnp.vnp_size,
5209 VM_CNT_INC(v_vnodein);
5210 VM_CNT_ADD(v_vnodepgsin, pgsin);
5212 br_flags = (mp != NULL && (mp->mnt_kern_flag & MNTK_UNMAPPED_BUFS)
5213 != 0) ? GB_UNMAPPED : 0;
5214 VM_OBJECT_WLOCK(object);
5216 for (i = 0; i < count; i++)
5217 vm_page_busy_downgrade(ma[i]);
5218 VM_OBJECT_WUNLOCK(object);
5221 for (i = 0; i < count; i++) {
5225 * Pages are shared busy and the object lock is not
5226 * owned, which together allow for the pages'
5227 * invalidation. The racy test for validity avoids
5228 * useless creation of the buffer for the most typical
5229 * case when invalidation is not used in redo or for
5230 * parallel read. The shared->excl upgrade loop at
5231 * the end of the function catches the race in a
5232 * reliable way (protected by the object lock).
5234 if (m->valid == VM_PAGE_BITS_ALL)
5237 poff = IDX_TO_OFF(m->pindex);
5238 poffe = MIN(poff + PAGE_SIZE, object->un_pager.vnp.vnp_size);
5239 for (; poff < poffe; poff += bsize) {
5240 lbn = get_lblkno(vp, poff);
5245 bsize = get_blksize(vp, lbn);
5246 error = bread_gb(vp, lbn, bsize, curthread->td_ucred,
5250 if (LIST_EMPTY(&bp->b_dep)) {
5252 * Invalidation clears m->valid, but
5253 * may leave B_CACHE flag if the
5254 * buffer existed at the invalidation
5255 * time. In this case, recycle the
5256 * buffer to do real read on next
5257 * bread() after redo.
5259 * Otherwise B_RELBUF is not strictly
5260 * necessary, enable to reduce buf
5263 if (buf_pager_relbuf ||
5264 m->valid != VM_PAGE_BITS_ALL)
5265 bp->b_flags |= B_RELBUF;
5267 bp->b_flags &= ~B_NOCACHE;
5273 KASSERT(1 /* racy, enable for debugging */ ||
5274 m->valid == VM_PAGE_BITS_ALL || i == count - 1,
5275 ("buf %d %p invalid", i, m));
5276 if (i == count - 1 && lpart) {
5277 VM_OBJECT_WLOCK(object);
5278 if (m->valid != 0 &&
5279 m->valid != VM_PAGE_BITS_ALL)
5280 vm_page_zero_invalid(m, TRUE);
5281 VM_OBJECT_WUNLOCK(object);
5287 VM_OBJECT_WLOCK(object);
5289 for (i = 0; i < count; i++) {
5290 vm_page_sunbusy(ma[i]);
5291 ma[i] = vm_page_grab(object, ma[i]->pindex, VM_ALLOC_NORMAL);
5294 * Since the pages were only sbusy while neither the
5295 * buffer nor the object lock was held by us, or
5296 * reallocated while vm_page_grab() slept for busy
5297 * relinguish, they could have been invalidated.
5298 * Recheck the valid bits and re-read as needed.
5300 * Note that the last page is made fully valid in the
5301 * read loop, and partial validity for the page at
5302 * index count - 1 could mean that the page was
5303 * invalidated or removed, so we must restart for
5306 if (ma[i]->valid != VM_PAGE_BITS_ALL)
5309 if (redo && error == 0)
5311 VM_OBJECT_WUNLOCK(object);
5312 return (error != 0 ? VM_PAGER_ERROR : VM_PAGER_OK);
5315 #include "opt_ddb.h"
5317 #include <ddb/ddb.h>
5319 /* DDB command to show buffer data */
5320 DB_SHOW_COMMAND(buffer, db_show_buffer)
5323 struct buf *bp = (struct buf *)addr;
5324 #ifdef FULL_BUF_TRACKING
5329 db_printf("usage: show buffer <addr>\n");
5333 db_printf("buf at %p\n", bp);
5334 db_printf("b_flags = 0x%b, b_xflags=0x%b\n",
5335 (u_int)bp->b_flags, PRINT_BUF_FLAGS,
5336 (u_int)bp->b_xflags, PRINT_BUF_XFLAGS);
5337 db_printf("b_vflags=0x%b b_ioflags0x%b\n",
5338 (u_int)bp->b_vflags, PRINT_BUF_VFLAGS,
5339 (u_int)bp->b_ioflags, PRINT_BIO_FLAGS);
5341 "b_error = %d, b_bufsize = %ld, b_bcount = %ld, b_resid = %ld\n"
5342 "b_bufobj = (%p), b_data = %p\n, b_blkno = %jd, b_lblkno = %jd, "
5343 "b_vp = %p, b_dep = %p\n",
5344 bp->b_error, bp->b_bufsize, bp->b_bcount, bp->b_resid,
5345 bp->b_bufobj, bp->b_data, (intmax_t)bp->b_blkno,
5346 (intmax_t)bp->b_lblkno, bp->b_vp, bp->b_dep.lh_first);
5347 db_printf("b_kvabase = %p, b_kvasize = %d\n",
5348 bp->b_kvabase, bp->b_kvasize);
5351 db_printf("b_npages = %d, pages(OBJ, IDX, PA): ", bp->b_npages);
5352 for (i = 0; i < bp->b_npages; i++) {
5356 db_printf("(%p, 0x%lx, 0x%lx)", m->object,
5358 (u_long)VM_PAGE_TO_PHYS(m));
5360 db_printf("( ??? )");
5361 if ((i + 1) < bp->b_npages)
5366 BUF_LOCKPRINTINFO(bp);
5367 #if defined(FULL_BUF_TRACKING)
5368 db_printf("b_io_tracking: b_io_tcnt = %u\n", bp->b_io_tcnt);
5370 i = bp->b_io_tcnt % BUF_TRACKING_SIZE;
5371 for (j = 1; j <= BUF_TRACKING_SIZE; j++) {
5372 if (bp->b_io_tracking[BUF_TRACKING_ENTRY(i - j)] == NULL)
5374 db_printf(" %2u: %s\n", j,
5375 bp->b_io_tracking[BUF_TRACKING_ENTRY(i - j)]);
5377 #elif defined(BUF_TRACKING)
5378 db_printf("b_io_tracking: %s\n", bp->b_io_tracking);
5383 DB_SHOW_COMMAND(bufqueues, bufqueues)
5385 struct bufdomain *bd;
5390 db_printf("bqempty: %d\n", bqempty.bq_len);
5392 for (i = 0; i < buf_domains; i++) {
5394 db_printf("Buf domain %d\n", i);
5395 db_printf("\tfreebufs\t%d\n", bd->bd_freebuffers);
5396 db_printf("\tlofreebufs\t%d\n", bd->bd_lofreebuffers);
5397 db_printf("\thifreebufs\t%d\n", bd->bd_hifreebuffers);
5399 db_printf("\tbufspace\t%ld\n", bd->bd_bufspace);
5400 db_printf("\tmaxbufspace\t%ld\n", bd->bd_maxbufspace);
5401 db_printf("\thibufspace\t%ld\n", bd->bd_hibufspace);
5402 db_printf("\tlobufspace\t%ld\n", bd->bd_lobufspace);
5403 db_printf("\tbufspacethresh\t%ld\n", bd->bd_bufspacethresh);
5405 db_printf("\tnumdirtybuffers\t%d\n", bd->bd_numdirtybuffers);
5406 db_printf("\tlodirtybuffers\t%d\n", bd->bd_lodirtybuffers);
5407 db_printf("\thidirtybuffers\t%d\n", bd->bd_hidirtybuffers);
5408 db_printf("\tdirtybufthresh\t%d\n", bd->bd_dirtybufthresh);
5411 TAILQ_FOREACH(bp, &bd->bd_cleanq->bq_queue, b_freelist)
5412 total += bp->b_bufsize;
5413 db_printf("\tcleanq count\t%d (%ld)\n",
5414 bd->bd_cleanq->bq_len, total);
5416 TAILQ_FOREACH(bp, &bd->bd_dirtyq.bq_queue, b_freelist)
5417 total += bp->b_bufsize;
5418 db_printf("\tdirtyq count\t%d (%ld)\n",
5419 bd->bd_dirtyq.bq_len, total);
5420 db_printf("\twakeup\t\t%d\n", bd->bd_wanted);
5421 db_printf("\tlim\t\t%d\n", bd->bd_lim);
5422 db_printf("\tCPU ");
5423 for (j = 0; j <= mp_maxid; j++)
5424 db_printf("%d, ", bd->bd_subq[j].bq_len);
5428 for (j = 0; j < nbuf; j++)
5429 if (buf[j].b_domain == i && BUF_ISLOCKED(&buf[j])) {
5431 total += buf[j].b_bufsize;
5433 db_printf("\tLocked buffers: %d space %ld\n", cnt, total);
5436 for (j = 0; j < nbuf; j++)
5437 if (buf[j].b_domain == i) {
5439 total += buf[j].b_bufsize;
5441 db_printf("\tTotal buffers: %d space %ld\n", cnt, total);
5445 DB_SHOW_COMMAND(lockedbufs, lockedbufs)
5450 for (i = 0; i < nbuf; i++) {
5452 if (BUF_ISLOCKED(bp)) {
5453 db_show_buffer((uintptr_t)bp, 1, 0, NULL);
5461 DB_SHOW_COMMAND(vnodebufs, db_show_vnodebufs)
5467 db_printf("usage: show vnodebufs <addr>\n");
5470 vp = (struct vnode *)addr;
5471 db_printf("Clean buffers:\n");
5472 TAILQ_FOREACH(bp, &vp->v_bufobj.bo_clean.bv_hd, b_bobufs) {
5473 db_show_buffer((uintptr_t)bp, 1, 0, NULL);
5476 db_printf("Dirty buffers:\n");
5477 TAILQ_FOREACH(bp, &vp->v_bufobj.bo_dirty.bv_hd, b_bobufs) {
5478 db_show_buffer((uintptr_t)bp, 1, 0, NULL);
5483 DB_COMMAND(countfreebufs, db_coundfreebufs)
5486 int i, used = 0, nfree = 0;
5489 db_printf("usage: countfreebufs\n");
5493 for (i = 0; i < nbuf; i++) {
5495 if (bp->b_qindex == QUEUE_EMPTY)
5501 db_printf("Counted %d free, %d used (%d tot)\n", nfree, used,
5503 db_printf("numfreebuffers is %d\n", numfreebuffers);