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>
91 static MALLOC_DEFINE(M_BIOBUF, "biobuf", "BIO buffer");
93 struct bio_ops bioops; /* I/O operation notification */
95 struct buf_ops buf_ops_bio = {
96 .bop_name = "buf_ops_bio",
97 .bop_write = bufwrite,
98 .bop_strategy = bufstrategy,
100 .bop_bdflush = bufbdflush,
104 struct mtx_padalign bq_lock;
105 TAILQ_HEAD(, buf) bq_queue;
107 uint16_t bq_subqueue;
109 } __aligned(CACHE_LINE_SIZE);
111 #define BQ_LOCKPTR(bq) (&(bq)->bq_lock)
112 #define BQ_LOCK(bq) mtx_lock(BQ_LOCKPTR((bq)))
113 #define BQ_UNLOCK(bq) mtx_unlock(BQ_LOCKPTR((bq)))
114 #define BQ_ASSERT_LOCKED(bq) mtx_assert(BQ_LOCKPTR((bq)), MA_OWNED)
117 struct bufqueue bd_subq[MAXCPU + 1]; /* Per-cpu sub queues + global */
118 struct bufqueue bd_dirtyq;
119 struct bufqueue *bd_cleanq;
120 struct mtx_padalign bd_run_lock;
125 long bd_bufspacethresh;
126 int bd_hifreebuffers;
127 int bd_lofreebuffers;
128 int bd_hidirtybuffers;
129 int bd_lodirtybuffers;
130 int bd_dirtybufthresh;
134 int __aligned(CACHE_LINE_SIZE) bd_numdirtybuffers;
135 int __aligned(CACHE_LINE_SIZE) bd_running;
136 long __aligned(CACHE_LINE_SIZE) bd_bufspace;
137 int __aligned(CACHE_LINE_SIZE) bd_freebuffers;
138 } __aligned(CACHE_LINE_SIZE);
140 #define BD_LOCKPTR(bd) (&(bd)->bd_cleanq->bq_lock)
141 #define BD_LOCK(bd) mtx_lock(BD_LOCKPTR((bd)))
142 #define BD_UNLOCK(bd) mtx_unlock(BD_LOCKPTR((bd)))
143 #define BD_ASSERT_LOCKED(bd) mtx_assert(BD_LOCKPTR((bd)), MA_OWNED)
144 #define BD_RUN_LOCKPTR(bd) (&(bd)->bd_run_lock)
145 #define BD_RUN_LOCK(bd) mtx_lock(BD_RUN_LOCKPTR((bd)))
146 #define BD_RUN_UNLOCK(bd) mtx_unlock(BD_RUN_LOCKPTR((bd)))
147 #define BD_DOMAIN(bd) (bd - bdomain)
149 static struct buf *buf; /* buffer header pool */
150 extern struct buf *swbuf; /* Swap buffer header pool. */
151 caddr_t unmapped_buf;
153 /* Used below and for softdep flushing threads in ufs/ffs/ffs_softdep.c */
154 struct proc *bufdaemonproc;
156 static int inmem(struct vnode *vp, daddr_t blkno);
157 static void vm_hold_free_pages(struct buf *bp, int newbsize);
158 static void vm_hold_load_pages(struct buf *bp, vm_offset_t from,
160 static void vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, vm_page_t m);
161 static void vfs_page_set_validclean(struct buf *bp, vm_ooffset_t off,
163 static void vfs_clean_pages_dirty_buf(struct buf *bp);
164 static void vfs_setdirty_locked_object(struct buf *bp);
165 static void vfs_vmio_invalidate(struct buf *bp);
166 static void vfs_vmio_truncate(struct buf *bp, int npages);
167 static void vfs_vmio_extend(struct buf *bp, int npages, int size);
168 static int vfs_bio_clcheck(struct vnode *vp, int size,
169 daddr_t lblkno, daddr_t blkno);
170 static void breada(struct vnode *, daddr_t *, int *, int, struct ucred *, int,
171 void (*)(struct buf *));
172 static int buf_flush(struct vnode *vp, struct bufdomain *, int);
173 static int flushbufqueues(struct vnode *, struct bufdomain *, int, int);
174 static void buf_daemon(void);
175 static __inline void bd_wakeup(void);
176 static int sysctl_runningspace(SYSCTL_HANDLER_ARGS);
177 static void bufkva_reclaim(vmem_t *, int);
178 static void bufkva_free(struct buf *);
179 static int buf_import(void *, void **, int, int, int);
180 static void buf_release(void *, void **, int);
181 static void maxbcachebuf_adjust(void);
182 static inline struct bufdomain *bufdomain(struct buf *);
183 static void bq_remove(struct bufqueue *bq, struct buf *bp);
184 static void bq_insert(struct bufqueue *bq, struct buf *bp, bool unlock);
185 static int buf_recycle(struct bufdomain *, bool kva);
186 static void bq_init(struct bufqueue *bq, int qindex, int cpu,
187 const char *lockname);
188 static void bd_init(struct bufdomain *bd);
189 static int bd_flushall(struct bufdomain *bd);
190 static int sysctl_bufdomain_long(SYSCTL_HANDLER_ARGS);
191 static int sysctl_bufdomain_int(SYSCTL_HANDLER_ARGS);
193 static int sysctl_bufspace(SYSCTL_HANDLER_ARGS);
194 int vmiodirenable = TRUE;
195 SYSCTL_INT(_vfs, OID_AUTO, vmiodirenable, CTLFLAG_RW, &vmiodirenable, 0,
196 "Use the VM system for directory writes");
197 long runningbufspace;
198 SYSCTL_LONG(_vfs, OID_AUTO, runningbufspace, CTLFLAG_RD, &runningbufspace, 0,
199 "Amount of presently outstanding async buffer io");
200 SYSCTL_PROC(_vfs, OID_AUTO, bufspace, CTLTYPE_LONG|CTLFLAG_MPSAFE|CTLFLAG_RD,
201 NULL, 0, sysctl_bufspace, "L", "Physical memory used for buffers");
202 static counter_u64_t bufkvaspace;
203 SYSCTL_COUNTER_U64(_vfs, OID_AUTO, bufkvaspace, CTLFLAG_RD, &bufkvaspace,
204 "Kernel virtual memory used for buffers");
205 static long maxbufspace;
206 SYSCTL_PROC(_vfs, OID_AUTO, maxbufspace,
207 CTLTYPE_LONG|CTLFLAG_MPSAFE|CTLFLAG_RW, &maxbufspace,
208 __offsetof(struct bufdomain, bd_maxbufspace), sysctl_bufdomain_long, "L",
209 "Maximum allowed value of bufspace (including metadata)");
210 static long bufmallocspace;
211 SYSCTL_LONG(_vfs, OID_AUTO, bufmallocspace, CTLFLAG_RD, &bufmallocspace, 0,
212 "Amount of malloced memory for buffers");
213 static long maxbufmallocspace;
214 SYSCTL_LONG(_vfs, OID_AUTO, maxmallocbufspace, CTLFLAG_RW, &maxbufmallocspace,
215 0, "Maximum amount of malloced memory for buffers");
216 static long lobufspace;
217 SYSCTL_PROC(_vfs, OID_AUTO, lobufspace,
218 CTLTYPE_LONG|CTLFLAG_MPSAFE|CTLFLAG_RW, &lobufspace,
219 __offsetof(struct bufdomain, bd_lobufspace), sysctl_bufdomain_long, "L",
220 "Minimum amount of buffers we want to have");
222 SYSCTL_PROC(_vfs, OID_AUTO, hibufspace,
223 CTLTYPE_LONG|CTLFLAG_MPSAFE|CTLFLAG_RW, &hibufspace,
224 __offsetof(struct bufdomain, bd_hibufspace), sysctl_bufdomain_long, "L",
225 "Maximum allowed value of bufspace (excluding metadata)");
227 SYSCTL_PROC(_vfs, OID_AUTO, bufspacethresh,
228 CTLTYPE_LONG|CTLFLAG_MPSAFE|CTLFLAG_RW, &bufspacethresh,
229 __offsetof(struct bufdomain, bd_bufspacethresh), sysctl_bufdomain_long, "L",
230 "Bufspace consumed before waking the daemon to free some");
231 static counter_u64_t buffreekvacnt;
232 SYSCTL_COUNTER_U64(_vfs, OID_AUTO, buffreekvacnt, CTLFLAG_RW, &buffreekvacnt,
233 "Number of times we have freed the KVA space from some buffer");
234 static counter_u64_t bufdefragcnt;
235 SYSCTL_COUNTER_U64(_vfs, OID_AUTO, bufdefragcnt, CTLFLAG_RW, &bufdefragcnt,
236 "Number of times we have had to repeat buffer allocation to defragment");
237 static long lorunningspace;
238 SYSCTL_PROC(_vfs, OID_AUTO, lorunningspace, CTLTYPE_LONG | CTLFLAG_MPSAFE |
239 CTLFLAG_RW, &lorunningspace, 0, sysctl_runningspace, "L",
240 "Minimum preferred space used for in-progress I/O");
241 static long hirunningspace;
242 SYSCTL_PROC(_vfs, OID_AUTO, hirunningspace, CTLTYPE_LONG | CTLFLAG_MPSAFE |
243 CTLFLAG_RW, &hirunningspace, 0, sysctl_runningspace, "L",
244 "Maximum amount of space to use for in-progress I/O");
245 int dirtybufferflushes;
246 SYSCTL_INT(_vfs, OID_AUTO, dirtybufferflushes, CTLFLAG_RW, &dirtybufferflushes,
247 0, "Number of bdwrite to bawrite conversions to limit dirty buffers");
249 SYSCTL_INT(_vfs, OID_AUTO, bdwriteskip, CTLFLAG_RW, &bdwriteskip,
250 0, "Number of buffers supplied to bdwrite with snapshot deadlock risk");
251 int altbufferflushes;
252 SYSCTL_INT(_vfs, OID_AUTO, altbufferflushes, CTLFLAG_RW, &altbufferflushes,
253 0, "Number of fsync flushes to limit dirty buffers");
254 static int recursiveflushes;
255 SYSCTL_INT(_vfs, OID_AUTO, recursiveflushes, CTLFLAG_RW, &recursiveflushes,
256 0, "Number of flushes skipped due to being recursive");
257 static int sysctl_numdirtybuffers(SYSCTL_HANDLER_ARGS);
258 SYSCTL_PROC(_vfs, OID_AUTO, numdirtybuffers,
259 CTLTYPE_INT|CTLFLAG_MPSAFE|CTLFLAG_RD, NULL, 0, sysctl_numdirtybuffers, "I",
260 "Number of buffers that are dirty (has unwritten changes) at the moment");
261 static int lodirtybuffers;
262 SYSCTL_PROC(_vfs, OID_AUTO, lodirtybuffers,
263 CTLTYPE_INT|CTLFLAG_MPSAFE|CTLFLAG_RW, &lodirtybuffers,
264 __offsetof(struct bufdomain, bd_lodirtybuffers), sysctl_bufdomain_int, "I",
265 "How many buffers we want to have free before bufdaemon can sleep");
266 static int hidirtybuffers;
267 SYSCTL_PROC(_vfs, OID_AUTO, hidirtybuffers,
268 CTLTYPE_INT|CTLFLAG_MPSAFE|CTLFLAG_RW, &hidirtybuffers,
269 __offsetof(struct bufdomain, bd_hidirtybuffers), sysctl_bufdomain_int, "I",
270 "When the number of dirty buffers is considered severe");
272 SYSCTL_PROC(_vfs, OID_AUTO, dirtybufthresh,
273 CTLTYPE_INT|CTLFLAG_MPSAFE|CTLFLAG_RW, &dirtybufthresh,
274 __offsetof(struct bufdomain, bd_dirtybufthresh), sysctl_bufdomain_int, "I",
275 "Number of bdwrite to bawrite conversions to clear dirty buffers");
276 static int numfreebuffers;
277 SYSCTL_INT(_vfs, OID_AUTO, numfreebuffers, CTLFLAG_RD, &numfreebuffers, 0,
278 "Number of free buffers");
279 static int lofreebuffers;
280 SYSCTL_PROC(_vfs, OID_AUTO, lofreebuffers,
281 CTLTYPE_INT|CTLFLAG_MPSAFE|CTLFLAG_RW, &lofreebuffers,
282 __offsetof(struct bufdomain, bd_lofreebuffers), sysctl_bufdomain_int, "I",
283 "Target number of free buffers");
284 static int hifreebuffers;
285 SYSCTL_PROC(_vfs, OID_AUTO, hifreebuffers,
286 CTLTYPE_INT|CTLFLAG_MPSAFE|CTLFLAG_RW, &hifreebuffers,
287 __offsetof(struct bufdomain, bd_hifreebuffers), sysctl_bufdomain_int, "I",
288 "Threshold for clean buffer recycling");
289 static counter_u64_t getnewbufcalls;
290 SYSCTL_COUNTER_U64(_vfs, OID_AUTO, getnewbufcalls, CTLFLAG_RD,
291 &getnewbufcalls, "Number of calls to getnewbuf");
292 static counter_u64_t getnewbufrestarts;
293 SYSCTL_COUNTER_U64(_vfs, OID_AUTO, getnewbufrestarts, CTLFLAG_RD,
295 "Number of times getnewbuf has had to restart a buffer acquisition");
296 static counter_u64_t mappingrestarts;
297 SYSCTL_COUNTER_U64(_vfs, OID_AUTO, mappingrestarts, CTLFLAG_RD,
299 "Number of times getblk has had to restart a buffer mapping for "
301 static counter_u64_t numbufallocfails;
302 SYSCTL_COUNTER_U64(_vfs, OID_AUTO, numbufallocfails, CTLFLAG_RW,
303 &numbufallocfails, "Number of times buffer allocations failed");
304 static int flushbufqtarget = 100;
305 SYSCTL_INT(_vfs, OID_AUTO, flushbufqtarget, CTLFLAG_RW, &flushbufqtarget, 0,
306 "Amount of work to do in flushbufqueues when helping bufdaemon");
307 static counter_u64_t notbufdflushes;
308 SYSCTL_COUNTER_U64(_vfs, OID_AUTO, notbufdflushes, CTLFLAG_RD, ¬bufdflushes,
309 "Number of dirty buffer flushes done by the bufdaemon helpers");
310 static long barrierwrites;
311 SYSCTL_LONG(_vfs, OID_AUTO, barrierwrites, CTLFLAG_RW, &barrierwrites, 0,
312 "Number of barrier writes");
313 SYSCTL_INT(_vfs, OID_AUTO, unmapped_buf_allowed, CTLFLAG_RD,
314 &unmapped_buf_allowed, 0,
315 "Permit the use of the unmapped i/o");
316 int maxbcachebuf = MAXBCACHEBUF;
317 SYSCTL_INT(_vfs, OID_AUTO, maxbcachebuf, CTLFLAG_RDTUN, &maxbcachebuf, 0,
318 "Maximum size of a buffer cache block");
321 * This lock synchronizes access to bd_request.
323 static struct mtx_padalign __exclusive_cache_line bdlock;
326 * This lock protects the runningbufreq and synchronizes runningbufwakeup and
327 * waitrunningbufspace().
329 static struct mtx_padalign __exclusive_cache_line rbreqlock;
332 * Lock that protects bdirtywait.
334 static struct mtx_padalign __exclusive_cache_line bdirtylock;
337 * Wakeup point for bufdaemon, as well as indicator of whether it is already
338 * active. Set to 1 when the bufdaemon is already "on" the queue, 0 when it
341 static int bd_request;
344 * Request for the buf daemon to write more buffers than is indicated by
345 * lodirtybuf. This may be necessary to push out excess dependencies or
346 * defragment the address space where a simple count of the number of dirty
347 * buffers is insufficient to characterize the demand for flushing them.
349 static int bd_speedupreq;
352 * Synchronization (sleep/wakeup) variable for active buffer space requests.
353 * Set when wait starts, cleared prior to wakeup().
354 * Used in runningbufwakeup() and waitrunningbufspace().
356 static int runningbufreq;
359 * Synchronization for bwillwrite() waiters.
361 static int bdirtywait;
364 * Definitions for the buffer free lists.
366 #define QUEUE_NONE 0 /* on no queue */
367 #define QUEUE_EMPTY 1 /* empty buffer headers */
368 #define QUEUE_DIRTY 2 /* B_DELWRI buffers */
369 #define QUEUE_CLEAN 3 /* non-B_DELWRI buffers */
370 #define QUEUE_SENTINEL 4 /* not an queue index, but mark for sentinel */
372 /* Maximum number of buffer domains. */
373 #define BUF_DOMAINS 8
375 struct bufdomainset bdlodirty; /* Domains > lodirty */
376 struct bufdomainset bdhidirty; /* Domains > hidirty */
378 /* Configured number of clean queues. */
379 static int __read_mostly buf_domains;
381 BITSET_DEFINE(bufdomainset, BUF_DOMAINS);
382 struct bufdomain __exclusive_cache_line bdomain[BUF_DOMAINS];
383 struct bufqueue __exclusive_cache_line bqempty;
386 * per-cpu empty buffer cache.
391 * Single global constant for BUF_WMESG, to avoid getting multiple references.
392 * buf_wmesg is referred from macros.
394 const char *buf_wmesg = BUF_WMESG;
397 sysctl_runningspace(SYSCTL_HANDLER_ARGS)
402 value = *(long *)arg1;
403 error = sysctl_handle_long(oidp, &value, 0, req);
404 if (error != 0 || req->newptr == NULL)
406 mtx_lock(&rbreqlock);
407 if (arg1 == &hirunningspace) {
408 if (value < lorunningspace)
411 hirunningspace = value;
413 KASSERT(arg1 == &lorunningspace,
414 ("%s: unknown arg1", __func__));
415 if (value > hirunningspace)
418 lorunningspace = value;
420 mtx_unlock(&rbreqlock);
425 sysctl_bufdomain_int(SYSCTL_HANDLER_ARGS)
431 value = *(int *)arg1;
432 error = sysctl_handle_int(oidp, &value, 0, req);
433 if (error != 0 || req->newptr == NULL)
435 *(int *)arg1 = value;
436 for (i = 0; i < buf_domains; i++)
437 *(int *)(uintptr_t)(((uintptr_t)&bdomain[i]) + arg2) =
444 sysctl_bufdomain_long(SYSCTL_HANDLER_ARGS)
450 value = *(long *)arg1;
451 error = sysctl_handle_long(oidp, &value, 0, req);
452 if (error != 0 || req->newptr == NULL)
454 *(long *)arg1 = value;
455 for (i = 0; i < buf_domains; i++)
456 *(long *)(uintptr_t)(((uintptr_t)&bdomain[i]) + arg2) =
462 #if defined(COMPAT_FREEBSD4) || defined(COMPAT_FREEBSD5) || \
463 defined(COMPAT_FREEBSD6) || defined(COMPAT_FREEBSD7)
465 sysctl_bufspace(SYSCTL_HANDLER_ARGS)
472 for (i = 0; i < buf_domains; i++)
473 lvalue += bdomain[i].bd_bufspace;
474 if (sizeof(int) == sizeof(long) || req->oldlen >= sizeof(long))
475 return (sysctl_handle_long(oidp, &lvalue, 0, req));
476 if (lvalue > INT_MAX)
477 /* On overflow, still write out a long to trigger ENOMEM. */
478 return (sysctl_handle_long(oidp, &lvalue, 0, req));
480 return (sysctl_handle_int(oidp, &ivalue, 0, req));
484 sysctl_bufspace(SYSCTL_HANDLER_ARGS)
490 for (i = 0; i < buf_domains; i++)
491 lvalue += bdomain[i].bd_bufspace;
492 return (sysctl_handle_long(oidp, &lvalue, 0, req));
497 sysctl_numdirtybuffers(SYSCTL_HANDLER_ARGS)
503 for (i = 0; i < buf_domains; i++)
504 value += bdomain[i].bd_numdirtybuffers;
505 return (sysctl_handle_int(oidp, &value, 0, req));
511 * Wakeup any bwillwrite() waiters.
516 mtx_lock(&bdirtylock);
521 mtx_unlock(&bdirtylock);
527 * Clear a domain from the appropriate bitsets when dirtybuffers
531 bd_clear(struct bufdomain *bd)
534 mtx_lock(&bdirtylock);
535 if (bd->bd_numdirtybuffers <= bd->bd_lodirtybuffers)
536 BIT_CLR(BUF_DOMAINS, BD_DOMAIN(bd), &bdlodirty);
537 if (bd->bd_numdirtybuffers <= bd->bd_hidirtybuffers)
538 BIT_CLR(BUF_DOMAINS, BD_DOMAIN(bd), &bdhidirty);
539 mtx_unlock(&bdirtylock);
545 * Set a domain in the appropriate bitsets when dirtybuffers
549 bd_set(struct bufdomain *bd)
552 mtx_lock(&bdirtylock);
553 if (bd->bd_numdirtybuffers > bd->bd_lodirtybuffers)
554 BIT_SET(BUF_DOMAINS, BD_DOMAIN(bd), &bdlodirty);
555 if (bd->bd_numdirtybuffers > bd->bd_hidirtybuffers)
556 BIT_SET(BUF_DOMAINS, BD_DOMAIN(bd), &bdhidirty);
557 mtx_unlock(&bdirtylock);
563 * Decrement the numdirtybuffers count by one and wakeup any
564 * threads blocked in bwillwrite().
567 bdirtysub(struct buf *bp)
569 struct bufdomain *bd;
573 num = atomic_fetchadd_int(&bd->bd_numdirtybuffers, -1);
574 if (num == (bd->bd_lodirtybuffers + bd->bd_hidirtybuffers) / 2)
576 if (num == bd->bd_lodirtybuffers || num == bd->bd_hidirtybuffers)
583 * Increment the numdirtybuffers count by one and wakeup the buf
587 bdirtyadd(struct buf *bp)
589 struct bufdomain *bd;
593 * Only do the wakeup once as we cross the boundary. The
594 * buf daemon will keep running until the condition clears.
597 num = atomic_fetchadd_int(&bd->bd_numdirtybuffers, 1);
598 if (num == (bd->bd_lodirtybuffers + bd->bd_hidirtybuffers) / 2)
600 if (num == bd->bd_lodirtybuffers || num == bd->bd_hidirtybuffers)
605 * bufspace_daemon_wakeup:
607 * Wakeup the daemons responsible for freeing clean bufs.
610 bufspace_daemon_wakeup(struct bufdomain *bd)
614 * avoid the lock if the daemon is running.
616 if (atomic_fetchadd_int(&bd->bd_running, 1) == 0) {
618 atomic_store_int(&bd->bd_running, 1);
619 wakeup(&bd->bd_running);
625 * bufspace_daemon_wait:
627 * Sleep until the domain falls below a limit or one second passes.
630 bufspace_daemon_wait(struct bufdomain *bd)
633 * Re-check our limits and sleep. bd_running must be
634 * cleared prior to checking the limits to avoid missed
635 * wakeups. The waker will adjust one of bufspace or
636 * freebuffers prior to checking bd_running.
639 atomic_store_int(&bd->bd_running, 0);
640 if (bd->bd_bufspace < bd->bd_bufspacethresh &&
641 bd->bd_freebuffers > bd->bd_lofreebuffers) {
642 msleep(&bd->bd_running, BD_RUN_LOCKPTR(bd), PRIBIO|PDROP,
645 /* Avoid spurious wakeups while running. */
646 atomic_store_int(&bd->bd_running, 1);
654 * Adjust the reported bufspace for a KVA managed buffer, possibly
655 * waking any waiters.
658 bufspace_adjust(struct buf *bp, int bufsize)
660 struct bufdomain *bd;
664 KASSERT((bp->b_flags & B_MALLOC) == 0,
665 ("bufspace_adjust: malloc buf %p", bp));
667 diff = bufsize - bp->b_bufsize;
669 atomic_subtract_long(&bd->bd_bufspace, -diff);
670 } else if (diff > 0) {
671 space = atomic_fetchadd_long(&bd->bd_bufspace, diff);
672 /* Wake up the daemon on the transition. */
673 if (space < bd->bd_bufspacethresh &&
674 space + diff >= bd->bd_bufspacethresh)
675 bufspace_daemon_wakeup(bd);
677 bp->b_bufsize = bufsize;
683 * Reserve bufspace before calling allocbuf(). metadata has a
684 * different space limit than data.
687 bufspace_reserve(struct bufdomain *bd, int size, bool metadata)
693 limit = bd->bd_maxbufspace;
695 limit = bd->bd_hibufspace;
696 space = atomic_fetchadd_long(&bd->bd_bufspace, size);
699 atomic_subtract_long(&bd->bd_bufspace, size);
703 /* Wake up the daemon on the transition. */
704 if (space < bd->bd_bufspacethresh && new >= bd->bd_bufspacethresh)
705 bufspace_daemon_wakeup(bd);
713 * Release reserved bufspace after bufspace_adjust() has consumed it.
716 bufspace_release(struct bufdomain *bd, int size)
719 atomic_subtract_long(&bd->bd_bufspace, size);
725 * Wait for bufspace, acting as the buf daemon if a locked vnode is
726 * supplied. bd_wanted must be set prior to polling for space. The
727 * operation must be re-tried on return.
730 bufspace_wait(struct bufdomain *bd, struct vnode *vp, int gbflags,
731 int slpflag, int slptimeo)
734 int error, fl, norunbuf;
736 if ((gbflags & GB_NOWAIT_BD) != 0)
741 while (bd->bd_wanted) {
742 if (vp != NULL && vp->v_type != VCHR &&
743 (td->td_pflags & TDP_BUFNEED) == 0) {
746 * getblk() is called with a vnode locked, and
747 * some majority of the dirty buffers may as
748 * well belong to the vnode. Flushing the
749 * buffers there would make a progress that
750 * cannot be achieved by the buf_daemon, that
751 * cannot lock the vnode.
753 norunbuf = ~(TDP_BUFNEED | TDP_NORUNNINGBUF) |
754 (td->td_pflags & TDP_NORUNNINGBUF);
757 * Play bufdaemon. The getnewbuf() function
758 * may be called while the thread owns lock
759 * for another dirty buffer for the same
760 * vnode, which makes it impossible to use
761 * VOP_FSYNC() there, due to the buffer lock
764 td->td_pflags |= TDP_BUFNEED | TDP_NORUNNINGBUF;
765 fl = buf_flush(vp, bd, flushbufqtarget);
766 td->td_pflags &= norunbuf;
770 if (bd->bd_wanted == 0)
773 error = msleep(&bd->bd_wanted, BD_LOCKPTR(bd),
774 (PRIBIO + 4) | slpflag, "newbuf", slptimeo);
785 * buffer space management daemon. Tries to maintain some marginal
786 * amount of free buffer space so that requesting processes neither
787 * block nor work to reclaim buffers.
790 bufspace_daemon(void *arg)
792 struct bufdomain *bd;
794 EVENTHANDLER_REGISTER(shutdown_pre_sync, kthread_shutdown, curthread,
795 SHUTDOWN_PRI_LAST + 100);
799 kthread_suspend_check();
802 * Free buffers from the clean queue until we meet our
805 * Theory of operation: The buffer cache is most efficient
806 * when some free buffer headers and space are always
807 * available to getnewbuf(). This daemon attempts to prevent
808 * the excessive blocking and synchronization associated
809 * with shortfall. It goes through three phases according
812 * 1) The daemon wakes up voluntarily once per-second
813 * during idle periods when the counters are below
814 * the wakeup thresholds (bufspacethresh, lofreebuffers).
816 * 2) The daemon wakes up as we cross the thresholds
817 * ahead of any potential blocking. This may bounce
818 * slightly according to the rate of consumption and
821 * 3) The daemon and consumers are starved for working
822 * clean buffers. This is the 'bufspace' sleep below
823 * which will inefficiently trade bufs with bqrelse
824 * until we return to condition 2.
826 while (bd->bd_bufspace > bd->bd_lobufspace ||
827 bd->bd_freebuffers < bd->bd_hifreebuffers) {
828 if (buf_recycle(bd, false) != 0) {
832 * Speedup dirty if we've run out of clean
833 * buffers. This is possible in particular
834 * because softdep may held many bufs locked
835 * pending writes to other bufs which are
836 * marked for delayed write, exhausting
837 * clean space until they are written.
842 msleep(&bd->bd_wanted, BD_LOCKPTR(bd),
843 PRIBIO|PDROP, "bufspace", hz/10);
849 bufspace_daemon_wait(bd);
856 * Adjust the reported bufspace for a malloc managed buffer, possibly
857 * waking any waiters.
860 bufmallocadjust(struct buf *bp, int bufsize)
864 KASSERT((bp->b_flags & B_MALLOC) != 0,
865 ("bufmallocadjust: non-malloc buf %p", bp));
866 diff = bufsize - bp->b_bufsize;
868 atomic_subtract_long(&bufmallocspace, -diff);
870 atomic_add_long(&bufmallocspace, diff);
871 bp->b_bufsize = bufsize;
877 * Wake up processes that are waiting on asynchronous writes to fall
878 * below lorunningspace.
884 mtx_lock(&rbreqlock);
887 wakeup(&runningbufreq);
889 mtx_unlock(&rbreqlock);
895 * Decrement the outstanding write count according.
898 runningbufwakeup(struct buf *bp)
902 bspace = bp->b_runningbufspace;
905 space = atomic_fetchadd_long(&runningbufspace, -bspace);
906 KASSERT(space >= bspace, ("runningbufspace underflow %ld %ld",
908 bp->b_runningbufspace = 0;
910 * Only acquire the lock and wakeup on the transition from exceeding
911 * the threshold to falling below it.
913 if (space < lorunningspace)
915 if (space - bspace > lorunningspace)
921 * waitrunningbufspace()
923 * runningbufspace is a measure of the amount of I/O currently
924 * running. This routine is used in async-write situations to
925 * prevent creating huge backups of pending writes to a device.
926 * Only asynchronous writes are governed by this function.
928 * This does NOT turn an async write into a sync write. It waits
929 * for earlier writes to complete and generally returns before the
930 * caller's write has reached the device.
933 waitrunningbufspace(void)
936 mtx_lock(&rbreqlock);
937 while (runningbufspace > hirunningspace) {
939 msleep(&runningbufreq, &rbreqlock, PVM, "wdrain", 0);
941 mtx_unlock(&rbreqlock);
946 * vfs_buf_test_cache:
948 * Called when a buffer is extended. This function clears the B_CACHE
949 * bit if the newly extended portion of the buffer does not contain
953 vfs_buf_test_cache(struct buf *bp, vm_ooffset_t foff, vm_offset_t off,
954 vm_offset_t size, vm_page_t m)
957 VM_OBJECT_ASSERT_LOCKED(m->object);
958 if (bp->b_flags & B_CACHE) {
959 int base = (foff + off) & PAGE_MASK;
960 if (vm_page_is_valid(m, base, size) == 0)
961 bp->b_flags &= ~B_CACHE;
965 /* Wake up the buffer daemon if necessary */
971 if (bd_request == 0) {
979 * Adjust the maxbcachbuf tunable.
982 maxbcachebuf_adjust(void)
987 * maxbcachebuf must be a power of 2 >= MAXBSIZE.
990 while (i * 2 <= maxbcachebuf)
993 if (maxbcachebuf < MAXBSIZE)
994 maxbcachebuf = MAXBSIZE;
995 if (maxbcachebuf > MAXPHYS)
996 maxbcachebuf = MAXPHYS;
997 if (bootverbose != 0 && maxbcachebuf != MAXBCACHEBUF)
998 printf("maxbcachebuf=%d\n", maxbcachebuf);
1002 * bd_speedup - speedup the buffer cache flushing code
1011 if (bd_speedupreq == 0 || bd_request == 0)
1016 wakeup(&bd_request);
1017 mtx_unlock(&bdlock);
1021 #define NSWBUF_MIN 16
1025 #define TRANSIENT_DENOM 5
1027 #define TRANSIENT_DENOM 10
1031 * Calculating buffer cache scaling values and reserve space for buffer
1032 * headers. This is called during low level kernel initialization and
1033 * may be called more then once. We CANNOT write to the memory area
1034 * being reserved at this time.
1037 kern_vfs_bio_buffer_alloc(caddr_t v, long physmem_est)
1040 long maxbuf, maxbuf_sz, buf_sz, biotmap_sz;
1043 * physmem_est is in pages. Convert it to kilobytes (assumes
1044 * PAGE_SIZE is >= 1K)
1046 physmem_est = physmem_est * (PAGE_SIZE / 1024);
1048 maxbcachebuf_adjust();
1050 * The nominal buffer size (and minimum KVA allocation) is BKVASIZE.
1051 * For the first 64MB of ram nominally allocate sufficient buffers to
1052 * cover 1/4 of our ram. Beyond the first 64MB allocate additional
1053 * buffers to cover 1/10 of our ram over 64MB. When auto-sizing
1054 * the buffer cache we limit the eventual kva reservation to
1057 * factor represents the 1/4 x ram conversion.
1060 int factor = 4 * BKVASIZE / 1024;
1063 if (physmem_est > 4096)
1064 nbuf += min((physmem_est - 4096) / factor,
1066 if (physmem_est > 65536)
1067 nbuf += min((physmem_est - 65536) * 2 / (factor * 5),
1068 32 * 1024 * 1024 / (factor * 5));
1070 if (maxbcache && nbuf > maxbcache / BKVASIZE)
1071 nbuf = maxbcache / BKVASIZE;
1076 /* XXX Avoid unsigned long overflows later on with maxbufspace. */
1077 maxbuf = (LONG_MAX / 3) / BKVASIZE;
1078 if (nbuf > maxbuf) {
1080 printf("Warning: nbufs lowered from %d to %ld\n", nbuf,
1086 * Ideal allocation size for the transient bio submap is 10%
1087 * of the maximal space buffer map. This roughly corresponds
1088 * to the amount of the buffer mapped for typical UFS load.
1090 * Clip the buffer map to reserve space for the transient
1091 * BIOs, if its extent is bigger than 90% (80% on i386) of the
1092 * maximum buffer map extent on the platform.
1094 * The fall-back to the maxbuf in case of maxbcache unset,
1095 * allows to not trim the buffer KVA for the architectures
1096 * with ample KVA space.
1098 if (bio_transient_maxcnt == 0 && unmapped_buf_allowed) {
1099 maxbuf_sz = maxbcache != 0 ? maxbcache : maxbuf * BKVASIZE;
1100 buf_sz = (long)nbuf * BKVASIZE;
1101 if (buf_sz < maxbuf_sz / TRANSIENT_DENOM *
1102 (TRANSIENT_DENOM - 1)) {
1104 * There is more KVA than memory. Do not
1105 * adjust buffer map size, and assign the rest
1106 * of maxbuf to transient map.
1108 biotmap_sz = maxbuf_sz - buf_sz;
1111 * Buffer map spans all KVA we could afford on
1112 * this platform. Give 10% (20% on i386) of
1113 * the buffer map to the transient bio map.
1115 biotmap_sz = buf_sz / TRANSIENT_DENOM;
1116 buf_sz -= biotmap_sz;
1118 if (biotmap_sz / INT_MAX > MAXPHYS)
1119 bio_transient_maxcnt = INT_MAX;
1121 bio_transient_maxcnt = biotmap_sz / MAXPHYS;
1123 * Artificially limit to 1024 simultaneous in-flight I/Os
1124 * using the transient mapping.
1126 if (bio_transient_maxcnt > 1024)
1127 bio_transient_maxcnt = 1024;
1129 nbuf = buf_sz / BKVASIZE;
1133 * swbufs are used as temporary holders for I/O, such as paging I/O.
1134 * We have no less then 16 and no more then 256.
1136 nswbuf = min(nbuf / 4, 256);
1137 TUNABLE_INT_FETCH("kern.nswbuf", &nswbuf);
1138 if (nswbuf < NSWBUF_MIN)
1139 nswbuf = NSWBUF_MIN;
1142 * Reserve space for the buffer cache buffers
1145 v = (caddr_t)(swbuf + nswbuf);
1147 v = (caddr_t)(buf + nbuf);
1152 /* Initialize the buffer subsystem. Called before use of any buffers. */
1159 KASSERT(maxbcachebuf >= MAXBSIZE,
1160 ("maxbcachebuf (%d) must be >= MAXBSIZE (%d)\n", maxbcachebuf,
1162 bq_init(&bqempty, QUEUE_EMPTY, -1, "bufq empty lock");
1163 mtx_init(&rbreqlock, "runningbufspace lock", NULL, MTX_DEF);
1164 mtx_init(&bdlock, "buffer daemon lock", NULL, MTX_DEF);
1165 mtx_init(&bdirtylock, "dirty buf lock", NULL, MTX_DEF);
1167 unmapped_buf = (caddr_t)kva_alloc(MAXPHYS);
1169 /* finally, initialize each buffer header and stick on empty q */
1170 for (i = 0; i < nbuf; i++) {
1172 bzero(bp, sizeof *bp);
1173 bp->b_flags = B_INVAL;
1174 bp->b_rcred = NOCRED;
1175 bp->b_wcred = NOCRED;
1176 bp->b_qindex = QUEUE_NONE;
1178 bp->b_subqueue = mp_maxid + 1;
1180 bp->b_data = bp->b_kvabase = unmapped_buf;
1181 LIST_INIT(&bp->b_dep);
1183 bq_insert(&bqempty, bp, false);
1187 * maxbufspace is the absolute maximum amount of buffer space we are
1188 * allowed to reserve in KVM and in real terms. The absolute maximum
1189 * is nominally used by metadata. hibufspace is the nominal maximum
1190 * used by most other requests. The differential is required to
1191 * ensure that metadata deadlocks don't occur.
1193 * maxbufspace is based on BKVASIZE. Allocating buffers larger then
1194 * this may result in KVM fragmentation which is not handled optimally
1195 * by the system. XXX This is less true with vmem. We could use
1198 maxbufspace = (long)nbuf * BKVASIZE;
1199 hibufspace = lmax(3 * maxbufspace / 4, maxbufspace - maxbcachebuf * 10);
1200 lobufspace = (hibufspace / 20) * 19; /* 95% */
1201 bufspacethresh = lobufspace + (hibufspace - lobufspace) / 2;
1204 * Note: The 16 MiB upper limit for hirunningspace was chosen
1205 * arbitrarily and may need further tuning. It corresponds to
1206 * 128 outstanding write IO requests (if IO size is 128 KiB),
1207 * which fits with many RAID controllers' tagged queuing limits.
1208 * The lower 1 MiB limit is the historical upper limit for
1211 hirunningspace = lmax(lmin(roundup(hibufspace / 64, maxbcachebuf),
1212 16 * 1024 * 1024), 1024 * 1024);
1213 lorunningspace = roundup((hirunningspace * 2) / 3, maxbcachebuf);
1216 * Limit the amount of malloc memory since it is wired permanently into
1217 * the kernel space. Even though this is accounted for in the buffer
1218 * allocation, we don't want the malloced region to grow uncontrolled.
1219 * The malloc scheme improves memory utilization significantly on
1220 * average (small) directories.
1222 maxbufmallocspace = hibufspace / 20;
1225 * Reduce the chance of a deadlock occurring by limiting the number
1226 * of delayed-write dirty buffers we allow to stack up.
1228 hidirtybuffers = nbuf / 4 + 20;
1229 dirtybufthresh = hidirtybuffers * 9 / 10;
1231 * To support extreme low-memory systems, make sure hidirtybuffers
1232 * cannot eat up all available buffer space. This occurs when our
1233 * minimum cannot be met. We try to size hidirtybuffers to 3/4 our
1234 * buffer space assuming BKVASIZE'd buffers.
1236 while ((long)hidirtybuffers * BKVASIZE > 3 * hibufspace / 4) {
1237 hidirtybuffers >>= 1;
1239 lodirtybuffers = hidirtybuffers / 2;
1242 * lofreebuffers should be sufficient to avoid stalling waiting on
1243 * buf headers under heavy utilization. The bufs in per-cpu caches
1244 * are counted as free but will be unavailable to threads executing
1247 * hifreebuffers is the free target for the bufspace daemon. This
1248 * should be set appropriately to limit work per-iteration.
1250 lofreebuffers = MIN((nbuf / 25) + (20 * mp_ncpus), 128 * mp_ncpus);
1251 hifreebuffers = (3 * lofreebuffers) / 2;
1252 numfreebuffers = nbuf;
1254 /* Setup the kva and free list allocators. */
1255 vmem_set_reclaim(buffer_arena, bufkva_reclaim);
1256 buf_zone = uma_zcache_create("buf free cache", sizeof(struct buf),
1257 NULL, NULL, NULL, NULL, buf_import, buf_release, NULL, 0);
1260 * Size the clean queue according to the amount of buffer space.
1261 * One queue per-256mb up to the max. More queues gives better
1262 * concurrency but less accurate LRU.
1264 buf_domains = MIN(howmany(maxbufspace, 256*1024*1024), BUF_DOMAINS);
1265 for (i = 0 ; i < buf_domains; i++) {
1266 struct bufdomain *bd;
1270 bd->bd_freebuffers = nbuf / buf_domains;
1271 bd->bd_hifreebuffers = hifreebuffers / buf_domains;
1272 bd->bd_lofreebuffers = lofreebuffers / buf_domains;
1273 bd->bd_bufspace = 0;
1274 bd->bd_maxbufspace = maxbufspace / buf_domains;
1275 bd->bd_hibufspace = hibufspace / buf_domains;
1276 bd->bd_lobufspace = lobufspace / buf_domains;
1277 bd->bd_bufspacethresh = bufspacethresh / buf_domains;
1278 bd->bd_numdirtybuffers = 0;
1279 bd->bd_hidirtybuffers = hidirtybuffers / buf_domains;
1280 bd->bd_lodirtybuffers = lodirtybuffers / buf_domains;
1281 bd->bd_dirtybufthresh = dirtybufthresh / buf_domains;
1282 /* Don't allow more than 2% of bufs in the per-cpu caches. */
1283 bd->bd_lim = nbuf / buf_domains / 50 / mp_ncpus;
1285 getnewbufcalls = counter_u64_alloc(M_WAITOK);
1286 getnewbufrestarts = counter_u64_alloc(M_WAITOK);
1287 mappingrestarts = counter_u64_alloc(M_WAITOK);
1288 numbufallocfails = counter_u64_alloc(M_WAITOK);
1289 notbufdflushes = counter_u64_alloc(M_WAITOK);
1290 buffreekvacnt = counter_u64_alloc(M_WAITOK);
1291 bufdefragcnt = counter_u64_alloc(M_WAITOK);
1292 bufkvaspace = counter_u64_alloc(M_WAITOK);
1297 vfs_buf_check_mapped(struct buf *bp)
1300 KASSERT(bp->b_kvabase != unmapped_buf,
1301 ("mapped buf: b_kvabase was not updated %p", bp));
1302 KASSERT(bp->b_data != unmapped_buf,
1303 ("mapped buf: b_data was not updated %p", bp));
1304 KASSERT(bp->b_data < unmapped_buf || bp->b_data >= unmapped_buf +
1305 MAXPHYS, ("b_data + b_offset unmapped %p", bp));
1309 vfs_buf_check_unmapped(struct buf *bp)
1312 KASSERT(bp->b_data == unmapped_buf,
1313 ("unmapped buf: corrupted b_data %p", bp));
1316 #define BUF_CHECK_MAPPED(bp) vfs_buf_check_mapped(bp)
1317 #define BUF_CHECK_UNMAPPED(bp) vfs_buf_check_unmapped(bp)
1319 #define BUF_CHECK_MAPPED(bp) do {} while (0)
1320 #define BUF_CHECK_UNMAPPED(bp) do {} while (0)
1324 isbufbusy(struct buf *bp)
1326 if (((bp->b_flags & B_INVAL) == 0 && BUF_ISLOCKED(bp)) ||
1327 ((bp->b_flags & (B_DELWRI | B_INVAL)) == B_DELWRI))
1333 * Shutdown the system cleanly to prepare for reboot, halt, or power off.
1336 bufshutdown(int show_busybufs)
1338 static int first_buf_printf = 1;
1340 int iter, nbusy, pbusy;
1346 * Sync filesystems for shutdown
1348 wdog_kern_pat(WD_LASTVAL);
1349 sys_sync(curthread, NULL);
1352 * With soft updates, some buffers that are
1353 * written will be remarked as dirty until other
1354 * buffers are written.
1356 for (iter = pbusy = 0; iter < 20; iter++) {
1358 for (bp = &buf[nbuf]; --bp >= buf; )
1362 if (first_buf_printf)
1363 printf("All buffers synced.");
1366 if (first_buf_printf) {
1367 printf("Syncing disks, buffers remaining... ");
1368 first_buf_printf = 0;
1370 printf("%d ", nbusy);
1375 wdog_kern_pat(WD_LASTVAL);
1376 sys_sync(curthread, NULL);
1380 * Spin for a while to allow interrupt threads to run.
1382 DELAY(50000 * iter);
1385 * Context switch several times to allow interrupt
1388 for (subiter = 0; subiter < 50 * iter; subiter++) {
1389 thread_lock(curthread);
1390 mi_switch(SW_VOL, NULL);
1391 thread_unlock(curthread);
1398 * Count only busy local buffers to prevent forcing
1399 * a fsck if we're just a client of a wedged NFS server
1402 for (bp = &buf[nbuf]; --bp >= buf; ) {
1403 if (isbufbusy(bp)) {
1405 /* XXX: This is bogus. We should probably have a BO_REMOTE flag instead */
1406 if (bp->b_dev == NULL) {
1407 TAILQ_REMOVE(&mountlist,
1408 bp->b_vp->v_mount, mnt_list);
1413 if (show_busybufs > 0) {
1415 "%d: buf:%p, vnode:%p, flags:%0x, blkno:%jd, lblkno:%jd, buflock:",
1416 nbusy, bp, bp->b_vp, bp->b_flags,
1417 (intmax_t)bp->b_blkno,
1418 (intmax_t)bp->b_lblkno);
1419 BUF_LOCKPRINTINFO(bp);
1420 if (show_busybufs > 1)
1428 * Failed to sync all blocks. Indicate this and don't
1429 * unmount filesystems (thus forcing an fsck on reboot).
1431 printf("Giving up on %d buffers\n", nbusy);
1432 DELAY(5000000); /* 5 seconds */
1434 if (!first_buf_printf)
1435 printf("Final sync complete\n");
1437 * Unmount filesystems
1439 if (panicstr == NULL)
1443 DELAY(100000); /* wait for console output to finish */
1447 bpmap_qenter(struct buf *bp)
1450 BUF_CHECK_MAPPED(bp);
1453 * bp->b_data is relative to bp->b_offset, but
1454 * bp->b_offset may be offset into the first page.
1456 bp->b_data = (caddr_t)trunc_page((vm_offset_t)bp->b_data);
1457 pmap_qenter((vm_offset_t)bp->b_data, bp->b_pages, bp->b_npages);
1458 bp->b_data = (caddr_t)((vm_offset_t)bp->b_data |
1459 (vm_offset_t)(bp->b_offset & PAGE_MASK));
1462 static inline struct bufdomain *
1463 bufdomain(struct buf *bp)
1466 return (&bdomain[bp->b_domain]);
1469 static struct bufqueue *
1470 bufqueue(struct buf *bp)
1473 switch (bp->b_qindex) {
1476 case QUEUE_SENTINEL:
1481 return (&bufdomain(bp)->bd_dirtyq);
1483 return (&bufdomain(bp)->bd_subq[bp->b_subqueue]);
1487 panic("bufqueue(%p): Unhandled type %d\n", bp, bp->b_qindex);
1491 * Return the locked bufqueue that bp is a member of.
1493 static struct bufqueue *
1494 bufqueue_acquire(struct buf *bp)
1496 struct bufqueue *bq, *nbq;
1499 * bp can be pushed from a per-cpu queue to the
1500 * cleanq while we're waiting on the lock. Retry
1501 * if the queues don't match.
1519 * Insert the buffer into the appropriate free list. Requires a
1520 * locked buffer on entry and buffer is unlocked before return.
1523 binsfree(struct buf *bp, int qindex)
1525 struct bufdomain *bd;
1526 struct bufqueue *bq;
1528 KASSERT(qindex == QUEUE_CLEAN || qindex == QUEUE_DIRTY,
1529 ("binsfree: Invalid qindex %d", qindex));
1530 BUF_ASSERT_XLOCKED(bp);
1533 * Handle delayed bremfree() processing.
1535 if (bp->b_flags & B_REMFREE) {
1536 if (bp->b_qindex == qindex) {
1537 bp->b_flags |= B_REUSE;
1538 bp->b_flags &= ~B_REMFREE;
1542 bq = bufqueue_acquire(bp);
1547 if (qindex == QUEUE_CLEAN) {
1548 if (bd->bd_lim != 0)
1549 bq = &bd->bd_subq[PCPU_GET(cpuid)];
1553 bq = &bd->bd_dirtyq;
1554 bq_insert(bq, bp, true);
1560 * Free a buffer to the buf zone once it no longer has valid contents.
1563 buf_free(struct buf *bp)
1566 if (bp->b_flags & B_REMFREE)
1568 if (bp->b_vflags & BV_BKGRDINPROG)
1569 panic("losing buffer 1");
1570 if (bp->b_rcred != NOCRED) {
1571 crfree(bp->b_rcred);
1572 bp->b_rcred = NOCRED;
1574 if (bp->b_wcred != NOCRED) {
1575 crfree(bp->b_wcred);
1576 bp->b_wcred = NOCRED;
1578 if (!LIST_EMPTY(&bp->b_dep))
1581 atomic_add_int(&bufdomain(bp)->bd_freebuffers, 1);
1583 uma_zfree(buf_zone, bp);
1589 * Import bufs into the uma cache from the buf list. The system still
1590 * expects a static array of bufs and much of the synchronization
1591 * around bufs assumes type stable storage. As a result, UMA is used
1592 * only as a per-cpu cache of bufs still maintained on a global list.
1595 buf_import(void *arg, void **store, int cnt, int domain, int flags)
1601 for (i = 0; i < cnt; i++) {
1602 bp = TAILQ_FIRST(&bqempty.bq_queue);
1605 bq_remove(&bqempty, bp);
1608 BQ_UNLOCK(&bqempty);
1616 * Release bufs from the uma cache back to the buffer queues.
1619 buf_release(void *arg, void **store, int cnt)
1621 struct bufqueue *bq;
1627 for (i = 0; i < cnt; i++) {
1629 /* Inline bq_insert() to batch locking. */
1630 TAILQ_INSERT_TAIL(&bq->bq_queue, bp, b_freelist);
1631 bp->b_flags &= ~(B_AGE | B_REUSE);
1633 bp->b_qindex = bq->bq_index;
1641 * Allocate an empty buffer header.
1644 buf_alloc(struct bufdomain *bd)
1650 * We can only run out of bufs in the buf zone if the average buf
1651 * is less than BKVASIZE. In this case the actual wait/block will
1652 * come from buf_reycle() failing to flush one of these small bufs.
1655 freebufs = atomic_fetchadd_int(&bd->bd_freebuffers, -1);
1657 bp = uma_zalloc(buf_zone, M_NOWAIT);
1659 atomic_fetchadd_int(&bd->bd_freebuffers, 1);
1660 bufspace_daemon_wakeup(bd);
1661 counter_u64_add(numbufallocfails, 1);
1665 * Wake-up the bufspace daemon on transition below threshold.
1667 if (freebufs == bd->bd_lofreebuffers)
1668 bufspace_daemon_wakeup(bd);
1670 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0)
1671 panic("getnewbuf_empty: Locked buf %p on free queue.", bp);
1673 KASSERT(bp->b_vp == NULL,
1674 ("bp: %p still has vnode %p.", bp, bp->b_vp));
1675 KASSERT((bp->b_flags & (B_DELWRI | B_NOREUSE)) == 0,
1676 ("invalid buffer %p flags %#x", bp, bp->b_flags));
1677 KASSERT((bp->b_xflags & (BX_VNCLEAN|BX_VNDIRTY)) == 0,
1678 ("bp: %p still on a buffer list. xflags %X", bp, bp->b_xflags));
1679 KASSERT(bp->b_npages == 0,
1680 ("bp: %p still has %d vm pages\n", bp, bp->b_npages));
1681 KASSERT(bp->b_kvasize == 0, ("bp: %p still has kva\n", bp));
1682 KASSERT(bp->b_bufsize == 0, ("bp: %p still has bufspace\n", bp));
1684 bp->b_domain = BD_DOMAIN(bd);
1690 bp->b_blkno = bp->b_lblkno = 0;
1691 bp->b_offset = NOOFFSET;
1697 bp->b_dirtyoff = bp->b_dirtyend = 0;
1698 bp->b_bufobj = NULL;
1699 bp->b_data = bp->b_kvabase = unmapped_buf;
1700 bp->b_fsprivate1 = NULL;
1701 bp->b_fsprivate2 = NULL;
1702 bp->b_fsprivate3 = NULL;
1703 LIST_INIT(&bp->b_dep);
1711 * Free a buffer from the given bufqueue. kva controls whether the
1712 * freed buf must own some kva resources. This is used for
1716 buf_recycle(struct bufdomain *bd, bool kva)
1718 struct bufqueue *bq;
1719 struct buf *bp, *nbp;
1722 counter_u64_add(bufdefragcnt, 1);
1726 KASSERT(BQ_LOCKPTR(bq) == BD_LOCKPTR(bd),
1727 ("buf_recycle: Locks don't match"));
1728 nbp = TAILQ_FIRST(&bq->bq_queue);
1731 * Run scan, possibly freeing data and/or kva mappings on the fly
1734 while ((bp = nbp) != NULL) {
1736 * Calculate next bp (we can only use it if we do not
1737 * release the bqlock).
1739 nbp = TAILQ_NEXT(bp, b_freelist);
1742 * If we are defragging then we need a buffer with
1743 * some kva to reclaim.
1745 if (kva && bp->b_kvasize == 0)
1748 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0)
1752 * Implement a second chance algorithm for frequently
1755 if ((bp->b_flags & B_REUSE) != 0) {
1756 TAILQ_REMOVE(&bq->bq_queue, bp, b_freelist);
1757 TAILQ_INSERT_TAIL(&bq->bq_queue, bp, b_freelist);
1758 bp->b_flags &= ~B_REUSE;
1764 * Skip buffers with background writes in progress.
1766 if ((bp->b_vflags & BV_BKGRDINPROG) != 0) {
1771 KASSERT(bp->b_qindex == QUEUE_CLEAN,
1772 ("buf_recycle: inconsistent queue %d bp %p",
1774 KASSERT(bp->b_domain == BD_DOMAIN(bd),
1775 ("getnewbuf: queue domain %d doesn't match request %d",
1776 bp->b_domain, (int)BD_DOMAIN(bd)));
1778 * NOTE: nbp is now entirely invalid. We can only restart
1779 * the scan from this point on.
1785 * Requeue the background write buffer with error and
1788 if ((bp->b_vflags & BV_BKGRDERR) != 0) {
1791 nbp = TAILQ_FIRST(&bq->bq_queue);
1794 bp->b_flags |= B_INVAL;
1807 * Mark the buffer for removal from the appropriate free list.
1811 bremfree(struct buf *bp)
1814 CTR3(KTR_BUF, "bremfree(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
1815 KASSERT((bp->b_flags & B_REMFREE) == 0,
1816 ("bremfree: buffer %p already marked for delayed removal.", bp));
1817 KASSERT(bp->b_qindex != QUEUE_NONE,
1818 ("bremfree: buffer %p not on a queue.", bp));
1819 BUF_ASSERT_XLOCKED(bp);
1821 bp->b_flags |= B_REMFREE;
1827 * Force an immediate removal from a free list. Used only in nfs when
1828 * it abuses the b_freelist pointer.
1831 bremfreef(struct buf *bp)
1833 struct bufqueue *bq;
1835 bq = bufqueue_acquire(bp);
1841 bq_init(struct bufqueue *bq, int qindex, int subqueue, const char *lockname)
1844 mtx_init(&bq->bq_lock, lockname, NULL, MTX_DEF);
1845 TAILQ_INIT(&bq->bq_queue);
1847 bq->bq_index = qindex;
1848 bq->bq_subqueue = subqueue;
1852 bd_init(struct bufdomain *bd)
1856 bd->bd_cleanq = &bd->bd_subq[mp_maxid + 1];
1857 bq_init(bd->bd_cleanq, QUEUE_CLEAN, mp_maxid + 1, "bufq clean lock");
1858 bq_init(&bd->bd_dirtyq, QUEUE_DIRTY, -1, "bufq dirty lock");
1859 for (i = 0; i <= mp_maxid; i++)
1860 bq_init(&bd->bd_subq[i], QUEUE_CLEAN, i,
1861 "bufq clean subqueue lock");
1862 mtx_init(&bd->bd_run_lock, "bufspace daemon run lock", NULL, MTX_DEF);
1868 * Removes a buffer from the free list, must be called with the
1869 * correct qlock held.
1872 bq_remove(struct bufqueue *bq, struct buf *bp)
1875 CTR3(KTR_BUF, "bq_remove(%p) vp %p flags %X",
1876 bp, bp->b_vp, bp->b_flags);
1877 KASSERT(bp->b_qindex != QUEUE_NONE,
1878 ("bq_remove: buffer %p not on a queue.", bp));
1879 KASSERT(bufqueue(bp) == bq,
1880 ("bq_remove: Remove buffer %p from wrong queue.", bp));
1882 BQ_ASSERT_LOCKED(bq);
1883 if (bp->b_qindex != QUEUE_EMPTY) {
1884 BUF_ASSERT_XLOCKED(bp);
1886 KASSERT(bq->bq_len >= 1,
1887 ("queue %d underflow", bp->b_qindex));
1888 TAILQ_REMOVE(&bq->bq_queue, bp, b_freelist);
1890 bp->b_qindex = QUEUE_NONE;
1891 bp->b_flags &= ~(B_REMFREE | B_REUSE);
1895 bd_flush(struct bufdomain *bd, struct bufqueue *bq)
1899 BQ_ASSERT_LOCKED(bq);
1900 if (bq != bd->bd_cleanq) {
1902 while ((bp = TAILQ_FIRST(&bq->bq_queue)) != NULL) {
1903 TAILQ_REMOVE(&bq->bq_queue, bp, b_freelist);
1904 TAILQ_INSERT_TAIL(&bd->bd_cleanq->bq_queue, bp,
1906 bp->b_subqueue = bd->bd_cleanq->bq_subqueue;
1908 bd->bd_cleanq->bq_len += bq->bq_len;
1911 if (bd->bd_wanted) {
1913 wakeup(&bd->bd_wanted);
1915 if (bq != bd->bd_cleanq)
1920 bd_flushall(struct bufdomain *bd)
1922 struct bufqueue *bq;
1926 if (bd->bd_lim == 0)
1929 for (i = 0; i <= mp_maxid; i++) {
1930 bq = &bd->bd_subq[i];
1931 if (bq->bq_len == 0)
1943 bq_insert(struct bufqueue *bq, struct buf *bp, bool unlock)
1945 struct bufdomain *bd;
1947 if (bp->b_qindex != QUEUE_NONE)
1948 panic("bq_insert: free buffer %p onto another queue?", bp);
1951 if (bp->b_flags & B_AGE) {
1952 /* Place this buf directly on the real queue. */
1953 if (bq->bq_index == QUEUE_CLEAN)
1956 TAILQ_INSERT_HEAD(&bq->bq_queue, bp, b_freelist);
1959 TAILQ_INSERT_TAIL(&bq->bq_queue, bp, b_freelist);
1961 bp->b_flags &= ~(B_AGE | B_REUSE);
1963 bp->b_qindex = bq->bq_index;
1964 bp->b_subqueue = bq->bq_subqueue;
1967 * Unlock before we notify so that we don't wakeup a waiter that
1968 * fails a trylock on the buf and sleeps again.
1973 if (bp->b_qindex == QUEUE_CLEAN) {
1975 * Flush the per-cpu queue and notify any waiters.
1977 if (bd->bd_wanted || (bq != bd->bd_cleanq &&
1978 bq->bq_len >= bd->bd_lim))
1987 * Free the kva allocation for a buffer.
1991 bufkva_free(struct buf *bp)
1995 if (bp->b_kvasize == 0) {
1996 KASSERT(bp->b_kvabase == unmapped_buf &&
1997 bp->b_data == unmapped_buf,
1998 ("Leaked KVA space on %p", bp));
1999 } else if (buf_mapped(bp))
2000 BUF_CHECK_MAPPED(bp);
2002 BUF_CHECK_UNMAPPED(bp);
2004 if (bp->b_kvasize == 0)
2007 vmem_free(buffer_arena, (vm_offset_t)bp->b_kvabase, bp->b_kvasize);
2008 counter_u64_add(bufkvaspace, -bp->b_kvasize);
2009 counter_u64_add(buffreekvacnt, 1);
2010 bp->b_data = bp->b_kvabase = unmapped_buf;
2017 * Allocate the buffer KVA and set b_kvasize and b_kvabase.
2020 bufkva_alloc(struct buf *bp, int maxsize, int gbflags)
2025 KASSERT((gbflags & GB_UNMAPPED) == 0 || (gbflags & GB_KVAALLOC) != 0,
2026 ("Invalid gbflags 0x%x in %s", gbflags, __func__));
2031 error = vmem_alloc(buffer_arena, maxsize, M_BESTFIT | M_NOWAIT, &addr);
2034 * Buffer map is too fragmented. Request the caller
2035 * to defragment the map.
2039 bp->b_kvabase = (caddr_t)addr;
2040 bp->b_kvasize = maxsize;
2041 counter_u64_add(bufkvaspace, bp->b_kvasize);
2042 if ((gbflags & GB_UNMAPPED) != 0) {
2043 bp->b_data = unmapped_buf;
2044 BUF_CHECK_UNMAPPED(bp);
2046 bp->b_data = bp->b_kvabase;
2047 BUF_CHECK_MAPPED(bp);
2055 * Reclaim buffer kva by freeing buffers holding kva. This is a vmem
2056 * callback that fires to avoid returning failure.
2059 bufkva_reclaim(vmem_t *vmem, int flags)
2066 for (i = 0; i < 5; i++) {
2067 for (q = 0; q < buf_domains; q++)
2068 if (buf_recycle(&bdomain[q], true) != 0)
2077 * Attempt to initiate asynchronous I/O on read-ahead blocks. We must
2078 * clear BIO_ERROR and B_INVAL prior to initiating I/O . If B_CACHE is set,
2079 * the buffer is valid and we do not have to do anything.
2082 breada(struct vnode * vp, daddr_t * rablkno, int * rabsize, int cnt,
2083 struct ucred * cred, int flags, void (*ckhashfunc)(struct buf *))
2088 for (i = 0; i < cnt; i++, rablkno++, rabsize++) {
2089 if (inmem(vp, *rablkno))
2091 rabp = getblk(vp, *rablkno, *rabsize, 0, 0, 0);
2092 if ((rabp->b_flags & B_CACHE) != 0) {
2096 if (!TD_IS_IDLETHREAD(curthread)) {
2100 racct_add_buf(curproc, rabp, 0);
2101 PROC_UNLOCK(curproc);
2104 curthread->td_ru.ru_inblock++;
2106 rabp->b_flags |= B_ASYNC;
2107 rabp->b_flags &= ~B_INVAL;
2108 if ((flags & GB_CKHASH) != 0) {
2109 rabp->b_flags |= B_CKHASH;
2110 rabp->b_ckhashcalc = ckhashfunc;
2112 rabp->b_ioflags &= ~BIO_ERROR;
2113 rabp->b_iocmd = BIO_READ;
2114 if (rabp->b_rcred == NOCRED && cred != NOCRED)
2115 rabp->b_rcred = crhold(cred);
2116 vfs_busy_pages(rabp, 0);
2118 rabp->b_iooffset = dbtob(rabp->b_blkno);
2124 * Entry point for bread() and breadn() via #defines in sys/buf.h.
2126 * Get a buffer with the specified data. Look in the cache first. We
2127 * must clear BIO_ERROR and B_INVAL prior to initiating I/O. If B_CACHE
2128 * is set, the buffer is valid and we do not have to do anything, see
2129 * getblk(). Also starts asynchronous I/O on read-ahead blocks.
2131 * Always return a NULL buffer pointer (in bpp) when returning an error.
2134 breadn_flags(struct vnode *vp, daddr_t blkno, int size, daddr_t *rablkno,
2135 int *rabsize, int cnt, struct ucred *cred, int flags,
2136 void (*ckhashfunc)(struct buf *), struct buf **bpp)
2140 int error, readwait, rv;
2142 CTR3(KTR_BUF, "breadn(%p, %jd, %d)", vp, blkno, size);
2145 * Can only return NULL if GB_LOCK_NOWAIT or GB_SPARSE flags
2148 error = getblkx(vp, blkno, size, 0, 0, flags, &bp);
2153 flags &= ~GB_NOSPARSE;
2157 * If not found in cache, do some I/O
2160 if ((bp->b_flags & B_CACHE) == 0) {
2161 if (!TD_IS_IDLETHREAD(td)) {
2164 PROC_LOCK(td->td_proc);
2165 racct_add_buf(td->td_proc, bp, 0);
2166 PROC_UNLOCK(td->td_proc);
2169 td->td_ru.ru_inblock++;
2171 bp->b_iocmd = BIO_READ;
2172 bp->b_flags &= ~B_INVAL;
2173 if ((flags & GB_CKHASH) != 0) {
2174 bp->b_flags |= B_CKHASH;
2175 bp->b_ckhashcalc = ckhashfunc;
2177 bp->b_ioflags &= ~BIO_ERROR;
2178 if (bp->b_rcred == NOCRED && cred != NOCRED)
2179 bp->b_rcred = crhold(cred);
2180 vfs_busy_pages(bp, 0);
2181 bp->b_iooffset = dbtob(bp->b_blkno);
2187 * Attempt to initiate asynchronous I/O on read-ahead blocks.
2189 breada(vp, rablkno, rabsize, cnt, cred, flags, ckhashfunc);
2203 * Write, release buffer on completion. (Done by iodone
2204 * if async). Do not bother writing anything if the buffer
2207 * Note that we set B_CACHE here, indicating that buffer is
2208 * fully valid and thus cacheable. This is true even of NFS
2209 * now so we set it generally. This could be set either here
2210 * or in biodone() since the I/O is synchronous. We put it
2214 bufwrite(struct buf *bp)
2221 CTR3(KTR_BUF, "bufwrite(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
2222 if ((bp->b_bufobj->bo_flag & BO_DEAD) != 0) {
2223 bp->b_flags |= B_INVAL | B_RELBUF;
2224 bp->b_flags &= ~B_CACHE;
2228 if (bp->b_flags & B_INVAL) {
2233 if (bp->b_flags & B_BARRIER)
2236 oldflags = bp->b_flags;
2238 BUF_ASSERT_HELD(bp);
2240 KASSERT(!(bp->b_vflags & BV_BKGRDINPROG),
2241 ("FFS background buffer should not get here %p", bp));
2245 vp_md = vp->v_vflag & VV_MD;
2250 * Mark the buffer clean. Increment the bufobj write count
2251 * before bundirty() call, to prevent other thread from seeing
2252 * empty dirty list and zero counter for writes in progress,
2253 * falsely indicating that the bufobj is clean.
2255 bufobj_wref(bp->b_bufobj);
2258 bp->b_flags &= ~B_DONE;
2259 bp->b_ioflags &= ~BIO_ERROR;
2260 bp->b_flags |= B_CACHE;
2261 bp->b_iocmd = BIO_WRITE;
2263 vfs_busy_pages(bp, 1);
2266 * Normal bwrites pipeline writes
2268 bp->b_runningbufspace = bp->b_bufsize;
2269 space = atomic_fetchadd_long(&runningbufspace, bp->b_runningbufspace);
2271 if (!TD_IS_IDLETHREAD(curthread)) {
2275 racct_add_buf(curproc, bp, 1);
2276 PROC_UNLOCK(curproc);
2279 curthread->td_ru.ru_oublock++;
2281 if (oldflags & B_ASYNC)
2283 bp->b_iooffset = dbtob(bp->b_blkno);
2284 buf_track(bp, __func__);
2287 if ((oldflags & B_ASYNC) == 0) {
2288 int rtval = bufwait(bp);
2291 } else if (space > hirunningspace) {
2293 * don't allow the async write to saturate the I/O
2294 * system. We will not deadlock here because
2295 * we are blocking waiting for I/O that is already in-progress
2296 * to complete. We do not block here if it is the update
2297 * or syncer daemon trying to clean up as that can lead
2300 if ((curthread->td_pflags & TDP_NORUNNINGBUF) == 0 && !vp_md)
2301 waitrunningbufspace();
2308 bufbdflush(struct bufobj *bo, struct buf *bp)
2312 if (bo->bo_dirty.bv_cnt > dirtybufthresh + 10) {
2313 (void) VOP_FSYNC(bp->b_vp, MNT_NOWAIT, curthread);
2315 } else if (bo->bo_dirty.bv_cnt > dirtybufthresh) {
2318 * Try to find a buffer to flush.
2320 TAILQ_FOREACH(nbp, &bo->bo_dirty.bv_hd, b_bobufs) {
2321 if ((nbp->b_vflags & BV_BKGRDINPROG) ||
2323 LK_EXCLUSIVE | LK_NOWAIT, NULL))
2326 panic("bdwrite: found ourselves");
2328 /* Don't countdeps with the bo lock held. */
2329 if (buf_countdeps(nbp, 0)) {
2334 if (nbp->b_flags & B_CLUSTEROK) {
2335 vfs_bio_awrite(nbp);
2340 dirtybufferflushes++;
2349 * Delayed write. (Buffer is marked dirty). Do not bother writing
2350 * anything if the buffer is marked invalid.
2352 * Note that since the buffer must be completely valid, we can safely
2353 * set B_CACHE. In fact, we have to set B_CACHE here rather then in
2354 * biodone() in order to prevent getblk from writing the buffer
2355 * out synchronously.
2358 bdwrite(struct buf *bp)
2360 struct thread *td = curthread;
2364 CTR3(KTR_BUF, "bdwrite(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
2365 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp));
2366 KASSERT((bp->b_flags & B_BARRIER) == 0,
2367 ("Barrier request in delayed write %p", bp));
2368 BUF_ASSERT_HELD(bp);
2370 if (bp->b_flags & B_INVAL) {
2376 * If we have too many dirty buffers, don't create any more.
2377 * If we are wildly over our limit, then force a complete
2378 * cleanup. Otherwise, just keep the situation from getting
2379 * out of control. Note that we have to avoid a recursive
2380 * disaster and not try to clean up after our own cleanup!
2384 if ((td->td_pflags & (TDP_COWINPROGRESS|TDP_INBDFLUSH)) == 0) {
2385 td->td_pflags |= TDP_INBDFLUSH;
2387 td->td_pflags &= ~TDP_INBDFLUSH;
2393 * Set B_CACHE, indicating that the buffer is fully valid. This is
2394 * true even of NFS now.
2396 bp->b_flags |= B_CACHE;
2399 * This bmap keeps the system from needing to do the bmap later,
2400 * perhaps when the system is attempting to do a sync. Since it
2401 * is likely that the indirect block -- or whatever other datastructure
2402 * that the filesystem needs is still in memory now, it is a good
2403 * thing to do this. Note also, that if the pageout daemon is
2404 * requesting a sync -- there might not be enough memory to do
2405 * the bmap then... So, this is important to do.
2407 if (vp->v_type != VCHR && bp->b_lblkno == bp->b_blkno) {
2408 VOP_BMAP(vp, bp->b_lblkno, NULL, &bp->b_blkno, NULL, NULL);
2411 buf_track(bp, __func__);
2414 * Set the *dirty* buffer range based upon the VM system dirty
2417 * Mark the buffer pages as clean. We need to do this here to
2418 * satisfy the vnode_pager and the pageout daemon, so that it
2419 * thinks that the pages have been "cleaned". Note that since
2420 * the pages are in a delayed write buffer -- the VFS layer
2421 * "will" see that the pages get written out on the next sync,
2422 * or perhaps the cluster will be completed.
2424 vfs_clean_pages_dirty_buf(bp);
2428 * note: we cannot initiate I/O from a bdwrite even if we wanted to,
2429 * due to the softdep code.
2436 * Turn buffer into delayed write request. We must clear BIO_READ and
2437 * B_RELBUF, and we must set B_DELWRI. We reassign the buffer to
2438 * itself to properly update it in the dirty/clean lists. We mark it
2439 * B_DONE to ensure that any asynchronization of the buffer properly
2440 * clears B_DONE ( else a panic will occur later ).
2442 * bdirty() is kinda like bdwrite() - we have to clear B_INVAL which
2443 * might have been set pre-getblk(). Unlike bwrite/bdwrite, bdirty()
2444 * should only be called if the buffer is known-good.
2446 * Since the buffer is not on a queue, we do not update the numfreebuffers
2449 * The buffer must be on QUEUE_NONE.
2452 bdirty(struct buf *bp)
2455 CTR3(KTR_BUF, "bdirty(%p) vp %p flags %X",
2456 bp, bp->b_vp, bp->b_flags);
2457 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp));
2458 KASSERT(bp->b_flags & B_REMFREE || bp->b_qindex == QUEUE_NONE,
2459 ("bdirty: buffer %p still on queue %d", bp, bp->b_qindex));
2460 BUF_ASSERT_HELD(bp);
2461 bp->b_flags &= ~(B_RELBUF);
2462 bp->b_iocmd = BIO_WRITE;
2464 if ((bp->b_flags & B_DELWRI) == 0) {
2465 bp->b_flags |= /* XXX B_DONE | */ B_DELWRI;
2474 * Clear B_DELWRI for buffer.
2476 * Since the buffer is not on a queue, we do not update the numfreebuffers
2479 * The buffer must be on QUEUE_NONE.
2483 bundirty(struct buf *bp)
2486 CTR3(KTR_BUF, "bundirty(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
2487 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp));
2488 KASSERT(bp->b_flags & B_REMFREE || bp->b_qindex == QUEUE_NONE,
2489 ("bundirty: buffer %p still on queue %d", bp, bp->b_qindex));
2490 BUF_ASSERT_HELD(bp);
2492 if (bp->b_flags & B_DELWRI) {
2493 bp->b_flags &= ~B_DELWRI;
2498 * Since it is now being written, we can clear its deferred write flag.
2500 bp->b_flags &= ~B_DEFERRED;
2506 * Asynchronous write. Start output on a buffer, but do not wait for
2507 * it to complete. The buffer is released when the output completes.
2509 * bwrite() ( or the VOP routine anyway ) is responsible for handling
2510 * B_INVAL buffers. Not us.
2513 bawrite(struct buf *bp)
2516 bp->b_flags |= B_ASYNC;
2523 * Asynchronous barrier write. Start output on a buffer, but do not
2524 * wait for it to complete. Place a write barrier after this write so
2525 * that this buffer and all buffers written before it are committed to
2526 * the disk before any buffers written after this write are committed
2527 * to the disk. The buffer is released when the output completes.
2530 babarrierwrite(struct buf *bp)
2533 bp->b_flags |= B_ASYNC | B_BARRIER;
2540 * Synchronous barrier write. Start output on a buffer and wait for
2541 * it to complete. Place a write barrier after this write so that
2542 * this buffer and all buffers written before it are committed to
2543 * the disk before any buffers written after this write are committed
2544 * to the disk. The buffer is released when the output completes.
2547 bbarrierwrite(struct buf *bp)
2550 bp->b_flags |= B_BARRIER;
2551 return (bwrite(bp));
2557 * Called prior to the locking of any vnodes when we are expecting to
2558 * write. We do not want to starve the buffer cache with too many
2559 * dirty buffers so we block here. By blocking prior to the locking
2560 * of any vnodes we attempt to avoid the situation where a locked vnode
2561 * prevents the various system daemons from flushing related buffers.
2567 if (buf_dirty_count_severe()) {
2568 mtx_lock(&bdirtylock);
2569 while (buf_dirty_count_severe()) {
2571 msleep(&bdirtywait, &bdirtylock, (PRIBIO + 4),
2574 mtx_unlock(&bdirtylock);
2579 * Return true if we have too many dirty buffers.
2582 buf_dirty_count_severe(void)
2585 return (!BIT_EMPTY(BUF_DOMAINS, &bdhidirty));
2591 * Release a busy buffer and, if requested, free its resources. The
2592 * buffer will be stashed in the appropriate bufqueue[] allowing it
2593 * to be accessed later as a cache entity or reused for other purposes.
2596 brelse(struct buf *bp)
2598 struct mount *v_mnt;
2602 * Many functions erroneously call brelse with a NULL bp under rare
2603 * error conditions. Simply return when called with a NULL bp.
2607 CTR3(KTR_BUF, "brelse(%p) vp %p flags %X",
2608 bp, bp->b_vp, bp->b_flags);
2609 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)),
2610 ("brelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp));
2611 KASSERT((bp->b_flags & B_VMIO) != 0 || (bp->b_flags & B_NOREUSE) == 0,
2612 ("brelse: non-VMIO buffer marked NOREUSE"));
2614 if (BUF_LOCKRECURSED(bp)) {
2616 * Do not process, in particular, do not handle the
2617 * B_INVAL/B_RELBUF and do not release to free list.
2623 if (bp->b_flags & B_MANAGED) {
2628 if ((bp->b_vflags & (BV_BKGRDINPROG | BV_BKGRDERR)) == BV_BKGRDERR) {
2629 BO_LOCK(bp->b_bufobj);
2630 bp->b_vflags &= ~BV_BKGRDERR;
2631 BO_UNLOCK(bp->b_bufobj);
2634 if (bp->b_iocmd == BIO_WRITE && (bp->b_ioflags & BIO_ERROR) &&
2635 (bp->b_error != ENXIO || !LIST_EMPTY(&bp->b_dep)) &&
2636 !(bp->b_flags & B_INVAL)) {
2638 * Failed write, redirty. All errors except ENXIO (which
2639 * means the device is gone) are treated as being
2642 * XXX Treating EIO as transient is not correct; the
2643 * contract with the local storage device drivers is that
2644 * they will only return EIO once the I/O is no longer
2645 * retriable. Network I/O also respects this through the
2646 * guarantees of TCP and/or the internal retries of NFS.
2647 * ENOMEM might be transient, but we also have no way of
2648 * knowing when its ok to retry/reschedule. In general,
2649 * this entire case should be made obsolete through better
2650 * error handling/recovery and resource scheduling.
2652 * Do this also for buffers that failed with ENXIO, but have
2653 * non-empty dependencies - the soft updates code might need
2654 * to access the buffer to untangle them.
2656 * Must clear BIO_ERROR to prevent pages from being scrapped.
2658 bp->b_ioflags &= ~BIO_ERROR;
2660 } else if ((bp->b_flags & (B_NOCACHE | B_INVAL)) ||
2661 (bp->b_ioflags & BIO_ERROR) || (bp->b_bufsize <= 0)) {
2663 * Either a failed read I/O, or we were asked to free or not
2664 * cache the buffer, or we failed to write to a device that's
2665 * no longer present.
2667 bp->b_flags |= B_INVAL;
2668 if (!LIST_EMPTY(&bp->b_dep))
2670 if (bp->b_flags & B_DELWRI)
2672 bp->b_flags &= ~(B_DELWRI | B_CACHE);
2673 if ((bp->b_flags & B_VMIO) == 0) {
2681 * We must clear B_RELBUF if B_DELWRI is set. If vfs_vmio_truncate()
2682 * is called with B_DELWRI set, the underlying pages may wind up
2683 * getting freed causing a previous write (bdwrite()) to get 'lost'
2684 * because pages associated with a B_DELWRI bp are marked clean.
2686 * We still allow the B_INVAL case to call vfs_vmio_truncate(), even
2687 * if B_DELWRI is set.
2689 if (bp->b_flags & B_DELWRI)
2690 bp->b_flags &= ~B_RELBUF;
2693 * VMIO buffer rundown. It is not very necessary to keep a VMIO buffer
2694 * constituted, not even NFS buffers now. Two flags effect this. If
2695 * B_INVAL, the struct buf is invalidated but the VM object is kept
2696 * around ( i.e. so it is trivial to reconstitute the buffer later ).
2698 * If BIO_ERROR or B_NOCACHE is set, pages in the VM object will be
2699 * invalidated. BIO_ERROR cannot be set for a failed write unless the
2700 * buffer is also B_INVAL because it hits the re-dirtying code above.
2702 * Normally we can do this whether a buffer is B_DELWRI or not. If
2703 * the buffer is an NFS buffer, it is tracking piecemeal writes or
2704 * the commit state and we cannot afford to lose the buffer. If the
2705 * buffer has a background write in progress, we need to keep it
2706 * around to prevent it from being reconstituted and starting a second
2710 v_mnt = bp->b_vp != NULL ? bp->b_vp->v_mount : NULL;
2712 if ((bp->b_flags & B_VMIO) && (bp->b_flags & B_NOCACHE ||
2713 (bp->b_ioflags & BIO_ERROR && bp->b_iocmd == BIO_READ)) &&
2714 (v_mnt == NULL || (v_mnt->mnt_vfc->vfc_flags & VFCF_NETWORK) == 0 ||
2715 vn_isdisk(bp->b_vp, NULL) || (bp->b_flags & B_DELWRI) == 0)) {
2716 vfs_vmio_invalidate(bp);
2720 if ((bp->b_flags & (B_INVAL | B_RELBUF)) != 0 ||
2721 (bp->b_flags & (B_DELWRI | B_NOREUSE)) == B_NOREUSE) {
2723 bp->b_flags &= ~B_NOREUSE;
2724 if (bp->b_vp != NULL)
2729 * If the buffer has junk contents signal it and eventually
2730 * clean up B_DELWRI and diassociate the vnode so that gbincore()
2733 if (bp->b_bufsize == 0 || (bp->b_ioflags & BIO_ERROR) != 0 ||
2734 (bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF)) != 0)
2735 bp->b_flags |= B_INVAL;
2736 if (bp->b_flags & B_INVAL) {
2737 if (bp->b_flags & B_DELWRI)
2743 buf_track(bp, __func__);
2745 /* buffers with no memory */
2746 if (bp->b_bufsize == 0) {
2750 /* buffers with junk contents */
2751 if (bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF) ||
2752 (bp->b_ioflags & BIO_ERROR)) {
2753 bp->b_xflags &= ~(BX_BKGRDWRITE | BX_ALTDATA);
2754 if (bp->b_vflags & BV_BKGRDINPROG)
2755 panic("losing buffer 2");
2756 qindex = QUEUE_CLEAN;
2757 bp->b_flags |= B_AGE;
2758 /* remaining buffers */
2759 } else if (bp->b_flags & B_DELWRI)
2760 qindex = QUEUE_DIRTY;
2762 qindex = QUEUE_CLEAN;
2764 if ((bp->b_flags & B_DELWRI) == 0 && (bp->b_xflags & BX_VNDIRTY))
2765 panic("brelse: not dirty");
2767 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_RELBUF | B_DIRECT);
2768 /* binsfree unlocks bp. */
2769 binsfree(bp, qindex);
2773 * Release a buffer back to the appropriate queue but do not try to free
2774 * it. The buffer is expected to be used again soon.
2776 * bqrelse() is used by bdwrite() to requeue a delayed write, and used by
2777 * biodone() to requeue an async I/O on completion. It is also used when
2778 * known good buffers need to be requeued but we think we may need the data
2781 * XXX we should be able to leave the B_RELBUF hint set on completion.
2784 bqrelse(struct buf *bp)
2788 CTR3(KTR_BUF, "bqrelse(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
2789 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)),
2790 ("bqrelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp));
2792 qindex = QUEUE_NONE;
2793 if (BUF_LOCKRECURSED(bp)) {
2794 /* do not release to free list */
2798 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF);
2800 if (bp->b_flags & B_MANAGED) {
2801 if (bp->b_flags & B_REMFREE)
2806 /* buffers with stale but valid contents */
2807 if ((bp->b_flags & B_DELWRI) != 0 || (bp->b_vflags & (BV_BKGRDINPROG |
2808 BV_BKGRDERR)) == BV_BKGRDERR) {
2809 BO_LOCK(bp->b_bufobj);
2810 bp->b_vflags &= ~BV_BKGRDERR;
2811 BO_UNLOCK(bp->b_bufobj);
2812 qindex = QUEUE_DIRTY;
2814 if ((bp->b_flags & B_DELWRI) == 0 &&
2815 (bp->b_xflags & BX_VNDIRTY))
2816 panic("bqrelse: not dirty");
2817 if ((bp->b_flags & B_NOREUSE) != 0) {
2821 qindex = QUEUE_CLEAN;
2823 buf_track(bp, __func__);
2824 /* binsfree unlocks bp. */
2825 binsfree(bp, qindex);
2829 buf_track(bp, __func__);
2835 * Complete I/O to a VMIO backed page. Validate the pages as appropriate,
2836 * restore bogus pages.
2839 vfs_vmio_iodone(struct buf *bp)
2844 struct vnode *vp __unused;
2845 int i, iosize, resid;
2848 obj = bp->b_bufobj->bo_object;
2849 KASSERT(obj->paging_in_progress >= bp->b_npages,
2850 ("vfs_vmio_iodone: paging in progress(%d) < b_npages(%d)",
2851 obj->paging_in_progress, bp->b_npages));
2854 KASSERT(vp->v_holdcnt > 0,
2855 ("vfs_vmio_iodone: vnode %p has zero hold count", vp));
2856 KASSERT(vp->v_object != NULL,
2857 ("vfs_vmio_iodone: vnode %p has no vm_object", vp));
2859 foff = bp->b_offset;
2860 KASSERT(bp->b_offset != NOOFFSET,
2861 ("vfs_vmio_iodone: bp %p has no buffer offset", bp));
2864 iosize = bp->b_bcount - bp->b_resid;
2865 VM_OBJECT_WLOCK(obj);
2866 for (i = 0; i < bp->b_npages; i++) {
2867 resid = ((foff + PAGE_SIZE) & ~(off_t)PAGE_MASK) - foff;
2872 * cleanup bogus pages, restoring the originals
2875 if (m == bogus_page) {
2877 m = vm_page_lookup(obj, OFF_TO_IDX(foff));
2879 panic("biodone: page disappeared!");
2881 } else if ((bp->b_iocmd == BIO_READ) && resid > 0) {
2883 * In the write case, the valid and clean bits are
2884 * already changed correctly ( see bdwrite() ), so we
2885 * only need to do this here in the read case.
2887 KASSERT((m->dirty & vm_page_bits(foff & PAGE_MASK,
2888 resid)) == 0, ("vfs_vmio_iodone: page %p "
2889 "has unexpected dirty bits", m));
2890 vfs_page_set_valid(bp, foff, m);
2892 KASSERT(OFF_TO_IDX(foff) == m->pindex,
2893 ("vfs_vmio_iodone: foff(%jd)/pindex(%ju) mismatch",
2894 (intmax_t)foff, (uintmax_t)m->pindex));
2897 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK;
2900 vm_object_pip_wakeupn(obj, bp->b_npages);
2901 VM_OBJECT_WUNLOCK(obj);
2902 if (bogus && buf_mapped(bp)) {
2903 BUF_CHECK_MAPPED(bp);
2904 pmap_qenter(trunc_page((vm_offset_t)bp->b_data),
2905 bp->b_pages, bp->b_npages);
2910 * Unwire a page held by a buf and either free it or update the page queues to
2911 * reflect its recent use.
2914 vfs_vmio_unwire(struct buf *bp, vm_page_t m)
2919 if (vm_page_unwire_noq(m)) {
2920 if ((bp->b_flags & B_DIRECT) != 0)
2921 freed = vm_page_try_to_free(m);
2926 * Use a racy check of the valid bits to determine
2927 * whether we can accelerate reclamation of the page.
2928 * The valid bits will be stable unless the page is
2929 * being mapped or is referenced by multiple buffers,
2930 * and in those cases we expect races to be rare. At
2931 * worst we will either accelerate reclamation of a
2932 * valid page and violate LRU, or unnecessarily defer
2933 * reclamation of an invalid page.
2935 * The B_NOREUSE flag marks data that is not expected to
2936 * be reused, so accelerate reclamation in that case
2937 * too. Otherwise, maintain LRU.
2939 if (m->valid == 0 || (bp->b_flags & B_NOREUSE) != 0)
2940 vm_page_deactivate_noreuse(m);
2941 else if (vm_page_active(m))
2942 vm_page_reference(m);
2944 vm_page_deactivate(m);
2951 * Perform page invalidation when a buffer is released. The fully invalid
2952 * pages will be reclaimed later in vfs_vmio_truncate().
2955 vfs_vmio_invalidate(struct buf *bp)
2959 int i, resid, poffset, presid;
2961 if (buf_mapped(bp)) {
2962 BUF_CHECK_MAPPED(bp);
2963 pmap_qremove(trunc_page((vm_offset_t)bp->b_data), bp->b_npages);
2965 BUF_CHECK_UNMAPPED(bp);
2967 * Get the base offset and length of the buffer. Note that
2968 * in the VMIO case if the buffer block size is not
2969 * page-aligned then b_data pointer may not be page-aligned.
2970 * But our b_pages[] array *IS* page aligned.
2972 * block sizes less then DEV_BSIZE (usually 512) are not
2973 * supported due to the page granularity bits (m->valid,
2974 * m->dirty, etc...).
2976 * See man buf(9) for more information
2978 obj = bp->b_bufobj->bo_object;
2979 resid = bp->b_bufsize;
2980 poffset = bp->b_offset & PAGE_MASK;
2981 VM_OBJECT_WLOCK(obj);
2982 for (i = 0; i < bp->b_npages; i++) {
2984 if (m == bogus_page)
2985 panic("vfs_vmio_invalidate: Unexpected bogus page.");
2986 bp->b_pages[i] = NULL;
2988 presid = resid > (PAGE_SIZE - poffset) ?
2989 (PAGE_SIZE - poffset) : resid;
2990 KASSERT(presid >= 0, ("brelse: extra page"));
2991 while (vm_page_xbusied(m)) {
2993 VM_OBJECT_WUNLOCK(obj);
2994 vm_page_busy_sleep(m, "mbncsh", true);
2995 VM_OBJECT_WLOCK(obj);
2997 if (pmap_page_wired_mappings(m) == 0)
2998 vm_page_set_invalid(m, poffset, presid);
2999 vfs_vmio_unwire(bp, m);
3003 VM_OBJECT_WUNLOCK(obj);
3008 * Page-granular truncation of an existing VMIO buffer.
3011 vfs_vmio_truncate(struct buf *bp, int desiredpages)
3017 if (bp->b_npages == desiredpages)
3020 if (buf_mapped(bp)) {
3021 BUF_CHECK_MAPPED(bp);
3022 pmap_qremove((vm_offset_t)trunc_page((vm_offset_t)bp->b_data) +
3023 (desiredpages << PAGE_SHIFT), bp->b_npages - desiredpages);
3025 BUF_CHECK_UNMAPPED(bp);
3028 * The object lock is needed only if we will attempt to free pages.
3030 obj = (bp->b_flags & B_DIRECT) != 0 ? bp->b_bufobj->bo_object : NULL;
3032 VM_OBJECT_WLOCK(obj);
3033 for (i = desiredpages; i < bp->b_npages; i++) {
3035 KASSERT(m != bogus_page, ("allocbuf: bogus page found"));
3036 bp->b_pages[i] = NULL;
3037 vfs_vmio_unwire(bp, m);
3040 VM_OBJECT_WUNLOCK(obj);
3041 bp->b_npages = desiredpages;
3045 * Byte granular extension of VMIO buffers.
3048 vfs_vmio_extend(struct buf *bp, int desiredpages, int size)
3051 * We are growing the buffer, possibly in a
3052 * byte-granular fashion.
3060 * Step 1, bring in the VM pages from the object, allocating
3061 * them if necessary. We must clear B_CACHE if these pages
3062 * are not valid for the range covered by the buffer.
3064 obj = bp->b_bufobj->bo_object;
3065 VM_OBJECT_WLOCK(obj);
3066 if (bp->b_npages < desiredpages) {
3068 * We must allocate system pages since blocking
3069 * here could interfere with paging I/O, no
3070 * matter which process we are.
3072 * Only exclusive busy can be tested here.
3073 * Blocking on shared busy might lead to
3074 * deadlocks once allocbuf() is called after
3075 * pages are vfs_busy_pages().
3077 (void)vm_page_grab_pages(obj,
3078 OFF_TO_IDX(bp->b_offset) + bp->b_npages,
3079 VM_ALLOC_SYSTEM | VM_ALLOC_IGN_SBUSY |
3080 VM_ALLOC_NOBUSY | VM_ALLOC_WIRED,
3081 &bp->b_pages[bp->b_npages], desiredpages - bp->b_npages);
3082 bp->b_npages = desiredpages;
3086 * Step 2. We've loaded the pages into the buffer,
3087 * we have to figure out if we can still have B_CACHE
3088 * set. Note that B_CACHE is set according to the
3089 * byte-granular range ( bcount and size ), not the
3090 * aligned range ( newbsize ).
3092 * The VM test is against m->valid, which is DEV_BSIZE
3093 * aligned. Needless to say, the validity of the data
3094 * needs to also be DEV_BSIZE aligned. Note that this
3095 * fails with NFS if the server or some other client
3096 * extends the file's EOF. If our buffer is resized,
3097 * B_CACHE may remain set! XXX
3099 toff = bp->b_bcount;
3100 tinc = PAGE_SIZE - ((bp->b_offset + toff) & PAGE_MASK);
3101 while ((bp->b_flags & B_CACHE) && toff < size) {
3104 if (tinc > (size - toff))
3106 pi = ((bp->b_offset & PAGE_MASK) + toff) >> PAGE_SHIFT;
3107 m = bp->b_pages[pi];
3108 vfs_buf_test_cache(bp, bp->b_offset, toff, tinc, m);
3112 VM_OBJECT_WUNLOCK(obj);
3115 * Step 3, fixup the KVA pmap.
3120 BUF_CHECK_UNMAPPED(bp);
3124 * Check to see if a block at a particular lbn is available for a clustered
3128 vfs_bio_clcheck(struct vnode *vp, int size, daddr_t lblkno, daddr_t blkno)
3135 /* If the buf isn't in core skip it */
3136 if ((bpa = gbincore(&vp->v_bufobj, lblkno)) == NULL)
3139 /* If the buf is busy we don't want to wait for it */
3140 if (BUF_LOCK(bpa, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0)
3143 /* Only cluster with valid clusterable delayed write buffers */
3144 if ((bpa->b_flags & (B_DELWRI | B_CLUSTEROK | B_INVAL)) !=
3145 (B_DELWRI | B_CLUSTEROK))
3148 if (bpa->b_bufsize != size)
3152 * Check to see if it is in the expected place on disk and that the
3153 * block has been mapped.
3155 if ((bpa->b_blkno != bpa->b_lblkno) && (bpa->b_blkno == blkno))
3165 * Implement clustered async writes for clearing out B_DELWRI buffers.
3166 * This is much better then the old way of writing only one buffer at
3167 * a time. Note that we may not be presented with the buffers in the
3168 * correct order, so we search for the cluster in both directions.
3171 vfs_bio_awrite(struct buf *bp)
3176 daddr_t lblkno = bp->b_lblkno;
3177 struct vnode *vp = bp->b_vp;
3185 gbflags = (bp->b_data == unmapped_buf) ? GB_UNMAPPED : 0;
3187 * right now we support clustered writing only to regular files. If
3188 * we find a clusterable block we could be in the middle of a cluster
3189 * rather then at the beginning.
3191 if ((vp->v_type == VREG) &&
3192 (vp->v_mount != 0) && /* Only on nodes that have the size info */
3193 (bp->b_flags & (B_CLUSTEROK | B_INVAL)) == B_CLUSTEROK) {
3195 size = vp->v_mount->mnt_stat.f_iosize;
3196 maxcl = MAXPHYS / size;
3199 for (i = 1; i < maxcl; i++)
3200 if (vfs_bio_clcheck(vp, size, lblkno + i,
3201 bp->b_blkno + ((i * size) >> DEV_BSHIFT)) == 0)
3204 for (j = 1; i + j <= maxcl && j <= lblkno; j++)
3205 if (vfs_bio_clcheck(vp, size, lblkno - j,
3206 bp->b_blkno - ((j * size) >> DEV_BSHIFT)) == 0)
3212 * this is a possible cluster write
3216 nwritten = cluster_wbuild(vp, size, lblkno - j, ncl,
3222 bp->b_flags |= B_ASYNC;
3224 * default (old) behavior, writing out only one block
3226 * XXX returns b_bufsize instead of b_bcount for nwritten?
3228 nwritten = bp->b_bufsize;
3237 * Allocate KVA for an empty buf header according to gbflags.
3240 getnewbuf_kva(struct buf *bp, int gbflags, int maxsize)
3243 if ((gbflags & (GB_UNMAPPED | GB_KVAALLOC)) != GB_UNMAPPED) {
3245 * In order to keep fragmentation sane we only allocate kva
3246 * in BKVASIZE chunks. XXX with vmem we can do page size.
3248 maxsize = (maxsize + BKVAMASK) & ~BKVAMASK;
3250 if (maxsize != bp->b_kvasize &&
3251 bufkva_alloc(bp, maxsize, gbflags))
3260 * Find and initialize a new buffer header, freeing up existing buffers
3261 * in the bufqueues as necessary. The new buffer is returned locked.
3264 * We have insufficient buffer headers
3265 * We have insufficient buffer space
3266 * buffer_arena is too fragmented ( space reservation fails )
3267 * If we have to flush dirty buffers ( but we try to avoid this )
3269 * The caller is responsible for releasing the reserved bufspace after
3270 * allocbuf() is called.
3273 getnewbuf(struct vnode *vp, int slpflag, int slptimeo, int maxsize, int gbflags)
3275 struct bufdomain *bd;
3277 bool metadata, reserved;
3280 KASSERT((gbflags & (GB_UNMAPPED | GB_KVAALLOC)) != GB_KVAALLOC,
3281 ("GB_KVAALLOC only makes sense with GB_UNMAPPED"));
3282 if (!unmapped_buf_allowed)
3283 gbflags &= ~(GB_UNMAPPED | GB_KVAALLOC);
3285 if (vp == NULL || (vp->v_vflag & (VV_MD | VV_SYSTEM)) != 0 ||
3293 bd = &bdomain[vp->v_bufobj.bo_domain];
3295 counter_u64_add(getnewbufcalls, 1);
3298 if (reserved == false &&
3299 bufspace_reserve(bd, maxsize, metadata) != 0) {
3300 counter_u64_add(getnewbufrestarts, 1);
3304 if ((bp = buf_alloc(bd)) == NULL) {
3305 counter_u64_add(getnewbufrestarts, 1);
3308 if (getnewbuf_kva(bp, gbflags, maxsize) == 0)
3311 } while (buf_recycle(bd, false) == 0);
3314 bufspace_release(bd, maxsize);
3316 bp->b_flags |= B_INVAL;
3319 bufspace_wait(bd, vp, gbflags, slpflag, slptimeo);
3327 * buffer flushing daemon. Buffers are normally flushed by the
3328 * update daemon but if it cannot keep up this process starts to
3329 * take the load in an attempt to prevent getnewbuf() from blocking.
3331 static struct kproc_desc buf_kp = {
3336 SYSINIT(bufdaemon, SI_SUB_KTHREAD_BUF, SI_ORDER_FIRST, kproc_start, &buf_kp);
3339 buf_flush(struct vnode *vp, struct bufdomain *bd, int target)
3343 flushed = flushbufqueues(vp, bd, target, 0);
3346 * Could not find any buffers without rollback
3347 * dependencies, so just write the first one
3348 * in the hopes of eventually making progress.
3350 if (vp != NULL && target > 2)
3352 flushbufqueues(vp, bd, target, 1);
3360 struct bufdomain *bd;
3366 * This process needs to be suspended prior to shutdown sync.
3368 EVENTHANDLER_REGISTER(shutdown_pre_sync, kthread_shutdown, curthread,
3369 SHUTDOWN_PRI_LAST + 100);
3372 * Start the buf clean daemons as children threads.
3374 for (i = 0 ; i < buf_domains; i++) {
3377 error = kthread_add((void (*)(void *))bufspace_daemon,
3378 &bdomain[i], curproc, NULL, 0, 0, "bufspacedaemon-%d", i);
3380 panic("error %d spawning bufspace daemon", error);
3384 * This process is allowed to take the buffer cache to the limit
3386 curthread->td_pflags |= TDP_NORUNNINGBUF | TDP_BUFNEED;
3390 mtx_unlock(&bdlock);
3392 kthread_suspend_check();
3395 * Save speedupreq for this pass and reset to capture new
3398 speedupreq = bd_speedupreq;
3402 * Flush each domain sequentially according to its level and
3403 * the speedup request.
3405 for (i = 0; i < buf_domains; i++) {
3408 lodirty = bd->bd_numdirtybuffers / 2;
3410 lodirty = bd->bd_lodirtybuffers;
3411 while (bd->bd_numdirtybuffers > lodirty) {
3412 if (buf_flush(NULL, bd,
3413 bd->bd_numdirtybuffers - lodirty) == 0)
3415 kern_yield(PRI_USER);
3420 * Only clear bd_request if we have reached our low water
3421 * mark. The buf_daemon normally waits 1 second and
3422 * then incrementally flushes any dirty buffers that have
3423 * built up, within reason.
3425 * If we were unable to hit our low water mark and couldn't
3426 * find any flushable buffers, we sleep for a short period
3427 * to avoid endless loops on unlockable buffers.
3430 if (!BIT_EMPTY(BUF_DOMAINS, &bdlodirty)) {
3432 * We reached our low water mark, reset the
3433 * request and sleep until we are needed again.
3434 * The sleep is just so the suspend code works.
3438 * Do an extra wakeup in case dirty threshold
3439 * changed via sysctl and the explicit transition
3440 * out of shortfall was missed.
3443 if (runningbufspace <= lorunningspace)
3445 msleep(&bd_request, &bdlock, PVM, "psleep", hz);
3448 * We couldn't find any flushable dirty buffers but
3449 * still have too many dirty buffers, we
3450 * have to sleep and try again. (rare)
3452 msleep(&bd_request, &bdlock, PVM, "qsleep", hz / 10);
3460 * Try to flush a buffer in the dirty queue. We must be careful to
3461 * free up B_INVAL buffers instead of write them, which NFS is
3462 * particularly sensitive to.
3464 static int flushwithdeps = 0;
3465 SYSCTL_INT(_vfs, OID_AUTO, flushwithdeps, CTLFLAG_RW, &flushwithdeps,
3466 0, "Number of buffers flushed with dependecies that require rollbacks");
3469 flushbufqueues(struct vnode *lvp, struct bufdomain *bd, int target,
3472 struct bufqueue *bq;
3473 struct buf *sentinel;
3483 bq = &bd->bd_dirtyq;
3485 sentinel = malloc(sizeof(struct buf), M_TEMP, M_WAITOK | M_ZERO);
3486 sentinel->b_qindex = QUEUE_SENTINEL;
3488 TAILQ_INSERT_HEAD(&bq->bq_queue, sentinel, b_freelist);
3490 while (flushed != target) {
3493 bp = TAILQ_NEXT(sentinel, b_freelist);
3495 TAILQ_REMOVE(&bq->bq_queue, sentinel, b_freelist);
3496 TAILQ_INSERT_AFTER(&bq->bq_queue, bp, sentinel,
3503 * Skip sentinels inserted by other invocations of the
3504 * flushbufqueues(), taking care to not reorder them.
3506 * Only flush the buffers that belong to the
3507 * vnode locked by the curthread.
3509 if (bp->b_qindex == QUEUE_SENTINEL || (lvp != NULL &&
3514 error = BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL);
3520 * BKGRDINPROG can only be set with the buf and bufobj
3521 * locks both held. We tolerate a race to clear it here.
3523 if ((bp->b_vflags & BV_BKGRDINPROG) != 0 ||
3524 (bp->b_flags & B_DELWRI) == 0) {
3528 if (bp->b_flags & B_INVAL) {
3535 if (!LIST_EMPTY(&bp->b_dep) && buf_countdeps(bp, 0)) {
3536 if (flushdeps == 0) {
3544 * We must hold the lock on a vnode before writing
3545 * one of its buffers. Otherwise we may confuse, or
3546 * in the case of a snapshot vnode, deadlock the
3549 * The lock order here is the reverse of the normal
3550 * of vnode followed by buf lock. This is ok because
3551 * the NOWAIT will prevent deadlock.
3554 if (vn_start_write(vp, &mp, V_NOWAIT) != 0) {
3560 error = vn_lock(vp, LK_EXCLUSIVE | LK_NOWAIT);
3562 ASSERT_VOP_LOCKED(vp, "getbuf");
3564 error = VOP_ISLOCKED(vp) == LK_EXCLUSIVE ? 0 :
3565 vn_lock(vp, LK_TRYUPGRADE);
3568 CTR3(KTR_BUF, "flushbufqueue(%p) vp %p flags %X",
3569 bp, bp->b_vp, bp->b_flags);
3570 if (curproc == bufdaemonproc) {
3575 counter_u64_add(notbufdflushes, 1);
3577 vn_finished_write(mp);
3580 flushwithdeps += hasdeps;
3584 * Sleeping on runningbufspace while holding
3585 * vnode lock leads to deadlock.
3587 if (curproc == bufdaemonproc &&
3588 runningbufspace > hirunningspace)
3589 waitrunningbufspace();
3592 vn_finished_write(mp);
3596 TAILQ_REMOVE(&bq->bq_queue, sentinel, b_freelist);
3598 free(sentinel, M_TEMP);
3603 * Check to see if a block is currently memory resident.
3606 incore(struct bufobj *bo, daddr_t blkno)
3611 bp = gbincore(bo, blkno);
3617 * Returns true if no I/O is needed to access the
3618 * associated VM object. This is like incore except
3619 * it also hunts around in the VM system for the data.
3623 inmem(struct vnode * vp, daddr_t blkno)
3626 vm_offset_t toff, tinc, size;
3630 ASSERT_VOP_LOCKED(vp, "inmem");
3632 if (incore(&vp->v_bufobj, blkno))
3634 if (vp->v_mount == NULL)
3641 if (size > vp->v_mount->mnt_stat.f_iosize)
3642 size = vp->v_mount->mnt_stat.f_iosize;
3643 off = (vm_ooffset_t)blkno * (vm_ooffset_t)vp->v_mount->mnt_stat.f_iosize;
3645 VM_OBJECT_RLOCK(obj);
3646 for (toff = 0; toff < vp->v_mount->mnt_stat.f_iosize; toff += tinc) {
3647 m = vm_page_lookup(obj, OFF_TO_IDX(off + toff));
3651 if (tinc > PAGE_SIZE - ((toff + off) & PAGE_MASK))
3652 tinc = PAGE_SIZE - ((toff + off) & PAGE_MASK);
3653 if (vm_page_is_valid(m,
3654 (vm_offset_t) ((toff + off) & PAGE_MASK), tinc) == 0)
3657 VM_OBJECT_RUNLOCK(obj);
3661 VM_OBJECT_RUNLOCK(obj);
3666 * Set the dirty range for a buffer based on the status of the dirty
3667 * bits in the pages comprising the buffer. The range is limited
3668 * to the size of the buffer.
3670 * Tell the VM system that the pages associated with this buffer
3671 * are clean. This is used for delayed writes where the data is
3672 * going to go to disk eventually without additional VM intevention.
3674 * Note that while we only really need to clean through to b_bcount, we
3675 * just go ahead and clean through to b_bufsize.
3678 vfs_clean_pages_dirty_buf(struct buf *bp)
3680 vm_ooffset_t foff, noff, eoff;
3684 if ((bp->b_flags & B_VMIO) == 0 || bp->b_bufsize == 0)
3687 foff = bp->b_offset;
3688 KASSERT(bp->b_offset != NOOFFSET,
3689 ("vfs_clean_pages_dirty_buf: no buffer offset"));
3691 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object);
3692 vfs_drain_busy_pages(bp);
3693 vfs_setdirty_locked_object(bp);
3694 for (i = 0; i < bp->b_npages; i++) {
3695 noff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK;
3697 if (eoff > bp->b_offset + bp->b_bufsize)
3698 eoff = bp->b_offset + bp->b_bufsize;
3700 vfs_page_set_validclean(bp, foff, m);
3701 /* vm_page_clear_dirty(m, foff & PAGE_MASK, eoff - foff); */
3704 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object);
3708 vfs_setdirty_locked_object(struct buf *bp)
3713 object = bp->b_bufobj->bo_object;
3714 VM_OBJECT_ASSERT_WLOCKED(object);
3717 * We qualify the scan for modified pages on whether the
3718 * object has been flushed yet.
3720 if ((object->flags & OBJ_MIGHTBEDIRTY) != 0) {
3721 vm_offset_t boffset;
3722 vm_offset_t eoffset;
3725 * test the pages to see if they have been modified directly
3726 * by users through the VM system.
3728 for (i = 0; i < bp->b_npages; i++)
3729 vm_page_test_dirty(bp->b_pages[i]);
3732 * Calculate the encompassing dirty range, boffset and eoffset,
3733 * (eoffset - boffset) bytes.
3736 for (i = 0; i < bp->b_npages; i++) {
3737 if (bp->b_pages[i]->dirty)
3740 boffset = (i << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK);
3742 for (i = bp->b_npages - 1; i >= 0; --i) {
3743 if (bp->b_pages[i]->dirty) {
3747 eoffset = ((i + 1) << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK);
3750 * Fit it to the buffer.
3753 if (eoffset > bp->b_bcount)
3754 eoffset = bp->b_bcount;
3757 * If we have a good dirty range, merge with the existing
3761 if (boffset < eoffset) {
3762 if (bp->b_dirtyoff > boffset)
3763 bp->b_dirtyoff = boffset;
3764 if (bp->b_dirtyend < eoffset)
3765 bp->b_dirtyend = eoffset;
3771 * Allocate the KVA mapping for an existing buffer.
3772 * If an unmapped buffer is provided but a mapped buffer is requested, take
3773 * also care to properly setup mappings between pages and KVA.
3776 bp_unmapped_get_kva(struct buf *bp, daddr_t blkno, int size, int gbflags)
3778 int bsize, maxsize, need_mapping, need_kva;
3781 need_mapping = bp->b_data == unmapped_buf &&
3782 (gbflags & GB_UNMAPPED) == 0;
3783 need_kva = bp->b_kvabase == unmapped_buf &&
3784 bp->b_data == unmapped_buf &&
3785 (gbflags & GB_KVAALLOC) != 0;
3786 if (!need_mapping && !need_kva)
3789 BUF_CHECK_UNMAPPED(bp);
3791 if (need_mapping && bp->b_kvabase != unmapped_buf) {
3793 * Buffer is not mapped, but the KVA was already
3794 * reserved at the time of the instantiation. Use the
3801 * Calculate the amount of the address space we would reserve
3802 * if the buffer was mapped.
3804 bsize = vn_isdisk(bp->b_vp, NULL) ? DEV_BSIZE : bp->b_bufobj->bo_bsize;
3805 KASSERT(bsize != 0, ("bsize == 0, check bo->bo_bsize"));
3806 offset = blkno * bsize;
3807 maxsize = size + (offset & PAGE_MASK);
3808 maxsize = imax(maxsize, bsize);
3810 while (bufkva_alloc(bp, maxsize, gbflags) != 0) {
3811 if ((gbflags & GB_NOWAIT_BD) != 0) {
3813 * XXXKIB: defragmentation cannot
3814 * succeed, not sure what else to do.
3816 panic("GB_NOWAIT_BD and GB_UNMAPPED %p", bp);
3818 counter_u64_add(mappingrestarts, 1);
3819 bufspace_wait(bufdomain(bp), bp->b_vp, gbflags, 0, 0);
3823 /* b_offset is handled by bpmap_qenter. */
3824 bp->b_data = bp->b_kvabase;
3825 BUF_CHECK_MAPPED(bp);
3831 getblk(struct vnode *vp, daddr_t blkno, int size, int slpflag, int slptimeo,
3837 error = getblkx(vp, blkno, size, slpflag, slptimeo, flags, &bp);
3846 * Get a block given a specified block and offset into a file/device.
3847 * The buffers B_DONE bit will be cleared on return, making it almost
3848 * ready for an I/O initiation. B_INVAL may or may not be set on
3849 * return. The caller should clear B_INVAL prior to initiating a
3852 * For a non-VMIO buffer, B_CACHE is set to the opposite of B_INVAL for
3853 * an existing buffer.
3855 * For a VMIO buffer, B_CACHE is modified according to the backing VM.
3856 * If getblk()ing a previously 0-sized invalid buffer, B_CACHE is set
3857 * and then cleared based on the backing VM. If the previous buffer is
3858 * non-0-sized but invalid, B_CACHE will be cleared.
3860 * If getblk() must create a new buffer, the new buffer is returned with
3861 * both B_INVAL and B_CACHE clear unless it is a VMIO buffer, in which
3862 * case it is returned with B_INVAL clear and B_CACHE set based on the
3865 * getblk() also forces a bwrite() for any B_DELWRI buffer whos
3866 * B_CACHE bit is clear.
3868 * What this means, basically, is that the caller should use B_CACHE to
3869 * determine whether the buffer is fully valid or not and should clear
3870 * B_INVAL prior to issuing a read. If the caller intends to validate
3871 * the buffer by loading its data area with something, the caller needs
3872 * to clear B_INVAL. If the caller does this without issuing an I/O,
3873 * the caller should set B_CACHE ( as an optimization ), else the caller
3874 * should issue the I/O and biodone() will set B_CACHE if the I/O was
3875 * a write attempt or if it was a successful read. If the caller
3876 * intends to issue a READ, the caller must clear B_INVAL and BIO_ERROR
3877 * prior to issuing the READ. biodone() will *not* clear B_INVAL.
3880 getblkx(struct vnode *vp, daddr_t blkno, int size, int slpflag, int slptimeo,
3881 int flags, struct buf **bpp)
3886 int bsize, error, maxsize, vmio;
3889 CTR3(KTR_BUF, "getblk(%p, %ld, %d)", vp, (long)blkno, size);
3890 KASSERT((flags & (GB_UNMAPPED | GB_KVAALLOC)) != GB_KVAALLOC,
3891 ("GB_KVAALLOC only makes sense with GB_UNMAPPED"));
3892 ASSERT_VOP_LOCKED(vp, "getblk");
3893 if (size > maxbcachebuf)
3894 panic("getblk: size(%d) > maxbcachebuf(%d)\n", size,
3896 if (!unmapped_buf_allowed)
3897 flags &= ~(GB_UNMAPPED | GB_KVAALLOC);
3903 bp = gbincore(bo, blkno);
3907 * Buffer is in-core. If the buffer is not busy nor managed,
3908 * it must be on a queue.
3910 lockflags = LK_EXCLUSIVE | LK_SLEEPFAIL | LK_INTERLOCK;
3912 if ((flags & GB_LOCK_NOWAIT) != 0)
3913 lockflags |= LK_NOWAIT;
3915 error = BUF_TIMELOCK(bp, lockflags,
3916 BO_LOCKPTR(bo), "getblk", slpflag, slptimeo);
3919 * If we slept and got the lock we have to restart in case
3920 * the buffer changed identities.
3922 if (error == ENOLCK)
3924 /* We timed out or were interrupted. */
3925 else if (error != 0)
3927 /* If recursed, assume caller knows the rules. */
3928 else if (BUF_LOCKRECURSED(bp))
3932 * The buffer is locked. B_CACHE is cleared if the buffer is
3933 * invalid. Otherwise, for a non-VMIO buffer, B_CACHE is set
3934 * and for a VMIO buffer B_CACHE is adjusted according to the
3937 if (bp->b_flags & B_INVAL)
3938 bp->b_flags &= ~B_CACHE;
3939 else if ((bp->b_flags & (B_VMIO | B_INVAL)) == 0)
3940 bp->b_flags |= B_CACHE;
3941 if (bp->b_flags & B_MANAGED)
3942 MPASS(bp->b_qindex == QUEUE_NONE);
3947 * check for size inconsistencies for non-VMIO case.
3949 if (bp->b_bcount != size) {
3950 if ((bp->b_flags & B_VMIO) == 0 ||
3951 (size > bp->b_kvasize)) {
3952 if (bp->b_flags & B_DELWRI) {
3953 bp->b_flags |= B_NOCACHE;
3956 if (LIST_EMPTY(&bp->b_dep)) {
3957 bp->b_flags |= B_RELBUF;
3960 bp->b_flags |= B_NOCACHE;
3969 * Handle the case of unmapped buffer which should
3970 * become mapped, or the buffer for which KVA
3971 * reservation is requested.
3973 bp_unmapped_get_kva(bp, blkno, size, flags);
3976 * If the size is inconsistent in the VMIO case, we can resize
3977 * the buffer. This might lead to B_CACHE getting set or
3978 * cleared. If the size has not changed, B_CACHE remains
3979 * unchanged from its previous state.
3983 KASSERT(bp->b_offset != NOOFFSET,
3984 ("getblk: no buffer offset"));
3987 * A buffer with B_DELWRI set and B_CACHE clear must
3988 * be committed before we can return the buffer in
3989 * order to prevent the caller from issuing a read
3990 * ( due to B_CACHE not being set ) and overwriting
3993 * Most callers, including NFS and FFS, need this to
3994 * operate properly either because they assume they
3995 * can issue a read if B_CACHE is not set, or because
3996 * ( for example ) an uncached B_DELWRI might loop due
3997 * to softupdates re-dirtying the buffer. In the latter
3998 * case, B_CACHE is set after the first write completes,
3999 * preventing further loops.
4000 * NOTE! b*write() sets B_CACHE. If we cleared B_CACHE
4001 * above while extending the buffer, we cannot allow the
4002 * buffer to remain with B_CACHE set after the write
4003 * completes or it will represent a corrupt state. To
4004 * deal with this we set B_NOCACHE to scrap the buffer
4007 * We might be able to do something fancy, like setting
4008 * B_CACHE in bwrite() except if B_DELWRI is already set,
4009 * so the below call doesn't set B_CACHE, but that gets real
4010 * confusing. This is much easier.
4013 if ((bp->b_flags & (B_CACHE|B_DELWRI)) == B_DELWRI) {
4014 bp->b_flags |= B_NOCACHE;
4018 bp->b_flags &= ~B_DONE;
4021 * Buffer is not in-core, create new buffer. The buffer
4022 * returned by getnewbuf() is locked. Note that the returned
4023 * buffer is also considered valid (not marked B_INVAL).
4027 * If the user does not want us to create the buffer, bail out
4030 if (flags & GB_NOCREAT)
4032 if (bdomain[bo->bo_domain].bd_freebuffers == 0 &&
4033 TD_IS_IDLETHREAD(curthread))
4036 bsize = vn_isdisk(vp, NULL) ? DEV_BSIZE : bo->bo_bsize;
4037 KASSERT(bsize != 0, ("bsize == 0, check bo->bo_bsize"));
4038 offset = blkno * bsize;
4039 vmio = vp->v_object != NULL;
4041 maxsize = size + (offset & PAGE_MASK);
4044 /* Do not allow non-VMIO notmapped buffers. */
4045 flags &= ~(GB_UNMAPPED | GB_KVAALLOC);
4047 maxsize = imax(maxsize, bsize);
4048 if ((flags & GB_NOSPARSE) != 0 && vmio &&
4049 !vn_isdisk(vp, NULL)) {
4050 error = VOP_BMAP(vp, blkno, NULL, &d_blkno, 0, 0);
4051 KASSERT(error != EOPNOTSUPP,
4052 ("GB_NOSPARSE from fs not supporting bmap, vp %p",
4057 return (EJUSTRETURN);
4060 bp = getnewbuf(vp, slpflag, slptimeo, maxsize, flags);
4062 if (slpflag || slptimeo)
4065 * XXX This is here until the sleep path is diagnosed
4066 * enough to work under very low memory conditions.
4068 * There's an issue on low memory, 4BSD+non-preempt
4069 * systems (eg MIPS routers with 32MB RAM) where buffer
4070 * exhaustion occurs without sleeping for buffer
4071 * reclaimation. This just sticks in a loop and
4072 * constantly attempts to allocate a buffer, which
4073 * hits exhaustion and tries to wakeup bufdaemon.
4074 * This never happens because we never yield.
4076 * The real solution is to identify and fix these cases
4077 * so we aren't effectively busy-waiting in a loop
4078 * until the reclaimation path has cycles to run.
4080 kern_yield(PRI_USER);
4085 * This code is used to make sure that a buffer is not
4086 * created while the getnewbuf routine is blocked.
4087 * This can be a problem whether the vnode is locked or not.
4088 * If the buffer is created out from under us, we have to
4089 * throw away the one we just created.
4091 * Note: this must occur before we associate the buffer
4092 * with the vp especially considering limitations in
4093 * the splay tree implementation when dealing with duplicate
4097 if (gbincore(bo, blkno)) {
4099 bp->b_flags |= B_INVAL;
4100 bufspace_release(bufdomain(bp), maxsize);
4106 * Insert the buffer into the hash, so that it can
4107 * be found by incore.
4109 bp->b_lblkno = blkno;
4110 bp->b_blkno = d_blkno;
4111 bp->b_offset = offset;
4116 * set B_VMIO bit. allocbuf() the buffer bigger. Since the
4117 * buffer size starts out as 0, B_CACHE will be set by
4118 * allocbuf() for the VMIO case prior to it testing the
4119 * backing store for validity.
4123 bp->b_flags |= B_VMIO;
4124 KASSERT(vp->v_object == bp->b_bufobj->bo_object,
4125 ("ARGH! different b_bufobj->bo_object %p %p %p\n",
4126 bp, vp->v_object, bp->b_bufobj->bo_object));
4128 bp->b_flags &= ~B_VMIO;
4129 KASSERT(bp->b_bufobj->bo_object == NULL,
4130 ("ARGH! has b_bufobj->bo_object %p %p\n",
4131 bp, bp->b_bufobj->bo_object));
4132 BUF_CHECK_MAPPED(bp);
4136 bufspace_release(bufdomain(bp), maxsize);
4137 bp->b_flags &= ~B_DONE;
4139 CTR4(KTR_BUF, "getblk(%p, %ld, %d) = %p", vp, (long)blkno, size, bp);
4140 BUF_ASSERT_HELD(bp);
4142 buf_track(bp, __func__);
4143 KASSERT(bp->b_bufobj == bo,
4144 ("bp %p wrong b_bufobj %p should be %p", bp, bp->b_bufobj, bo));
4150 * Get an empty, disassociated buffer of given size. The buffer is initially
4154 geteblk(int size, int flags)
4159 maxsize = (size + BKVAMASK) & ~BKVAMASK;
4160 while ((bp = getnewbuf(NULL, 0, 0, maxsize, flags)) == NULL) {
4161 if ((flags & GB_NOWAIT_BD) &&
4162 (curthread->td_pflags & TDP_BUFNEED) != 0)
4166 bufspace_release(bufdomain(bp), maxsize);
4167 bp->b_flags |= B_INVAL; /* b_dep cleared by getnewbuf() */
4168 BUF_ASSERT_HELD(bp);
4173 * Truncate the backing store for a non-vmio buffer.
4176 vfs_nonvmio_truncate(struct buf *bp, int newbsize)
4179 if (bp->b_flags & B_MALLOC) {
4181 * malloced buffers are not shrunk
4183 if (newbsize == 0) {
4184 bufmallocadjust(bp, 0);
4185 free(bp->b_data, M_BIOBUF);
4186 bp->b_data = bp->b_kvabase;
4187 bp->b_flags &= ~B_MALLOC;
4191 vm_hold_free_pages(bp, newbsize);
4192 bufspace_adjust(bp, newbsize);
4196 * Extend the backing for a non-VMIO buffer.
4199 vfs_nonvmio_extend(struct buf *bp, int newbsize)
4205 * We only use malloced memory on the first allocation.
4206 * and revert to page-allocated memory when the buffer
4209 * There is a potential smp race here that could lead
4210 * to bufmallocspace slightly passing the max. It
4211 * is probably extremely rare and not worth worrying
4214 if (bp->b_bufsize == 0 && newbsize <= PAGE_SIZE/2 &&
4215 bufmallocspace < maxbufmallocspace) {
4216 bp->b_data = malloc(newbsize, M_BIOBUF, M_WAITOK);
4217 bp->b_flags |= B_MALLOC;
4218 bufmallocadjust(bp, newbsize);
4223 * If the buffer is growing on its other-than-first
4224 * allocation then we revert to the page-allocation
4229 if (bp->b_flags & B_MALLOC) {
4230 origbuf = bp->b_data;
4231 origbufsize = bp->b_bufsize;
4232 bp->b_data = bp->b_kvabase;
4233 bufmallocadjust(bp, 0);
4234 bp->b_flags &= ~B_MALLOC;
4235 newbsize = round_page(newbsize);
4237 vm_hold_load_pages(bp, (vm_offset_t) bp->b_data + bp->b_bufsize,
4238 (vm_offset_t) bp->b_data + newbsize);
4239 if (origbuf != NULL) {
4240 bcopy(origbuf, bp->b_data, origbufsize);
4241 free(origbuf, M_BIOBUF);
4243 bufspace_adjust(bp, newbsize);
4247 * This code constitutes the buffer memory from either anonymous system
4248 * memory (in the case of non-VMIO operations) or from an associated
4249 * VM object (in the case of VMIO operations). This code is able to
4250 * resize a buffer up or down.
4252 * Note that this code is tricky, and has many complications to resolve
4253 * deadlock or inconsistent data situations. Tread lightly!!!
4254 * There are B_CACHE and B_DELWRI interactions that must be dealt with by
4255 * the caller. Calling this code willy nilly can result in the loss of data.
4257 * allocbuf() only adjusts B_CACHE for VMIO buffers. getblk() deals with
4258 * B_CACHE for the non-VMIO case.
4261 allocbuf(struct buf *bp, int size)
4265 BUF_ASSERT_HELD(bp);
4267 if (bp->b_bcount == size)
4270 if (bp->b_kvasize != 0 && bp->b_kvasize < size)
4271 panic("allocbuf: buffer too small");
4273 newbsize = roundup2(size, DEV_BSIZE);
4274 if ((bp->b_flags & B_VMIO) == 0) {
4275 if ((bp->b_flags & B_MALLOC) == 0)
4276 newbsize = round_page(newbsize);
4278 * Just get anonymous memory from the kernel. Don't
4279 * mess with B_CACHE.
4281 if (newbsize < bp->b_bufsize)
4282 vfs_nonvmio_truncate(bp, newbsize);
4283 else if (newbsize > bp->b_bufsize)
4284 vfs_nonvmio_extend(bp, newbsize);
4288 desiredpages = (size == 0) ? 0 :
4289 num_pages((bp->b_offset & PAGE_MASK) + newbsize);
4291 if (bp->b_flags & B_MALLOC)
4292 panic("allocbuf: VMIO buffer can't be malloced");
4294 * Set B_CACHE initially if buffer is 0 length or will become
4297 if (size == 0 || bp->b_bufsize == 0)
4298 bp->b_flags |= B_CACHE;
4300 if (newbsize < bp->b_bufsize)
4301 vfs_vmio_truncate(bp, desiredpages);
4302 /* XXX This looks as if it should be newbsize > b_bufsize */
4303 else if (size > bp->b_bcount)
4304 vfs_vmio_extend(bp, desiredpages, size);
4305 bufspace_adjust(bp, newbsize);
4307 bp->b_bcount = size; /* requested buffer size. */
4311 extern int inflight_transient_maps;
4313 static struct bio_queue nondump_bios;
4316 biodone(struct bio *bp)
4319 void (*done)(struct bio *);
4320 vm_offset_t start, end;
4322 biotrack(bp, __func__);
4325 * Avoid completing I/O when dumping after a panic since that may
4326 * result in a deadlock in the filesystem or pager code. Note that
4327 * this doesn't affect dumps that were started manually since we aim
4328 * to keep the system usable after it has been resumed.
4330 if (__predict_false(dumping && SCHEDULER_STOPPED())) {
4331 TAILQ_INSERT_HEAD(&nondump_bios, bp, bio_queue);
4334 if ((bp->bio_flags & BIO_TRANSIENT_MAPPING) != 0) {
4335 bp->bio_flags &= ~BIO_TRANSIENT_MAPPING;
4336 bp->bio_flags |= BIO_UNMAPPED;
4337 start = trunc_page((vm_offset_t)bp->bio_data);
4338 end = round_page((vm_offset_t)bp->bio_data + bp->bio_length);
4339 bp->bio_data = unmapped_buf;
4340 pmap_qremove(start, atop(end - start));
4341 vmem_free(transient_arena, start, end - start);
4342 atomic_add_int(&inflight_transient_maps, -1);
4344 done = bp->bio_done;
4346 mtxp = mtx_pool_find(mtxpool_sleep, bp);
4348 bp->bio_flags |= BIO_DONE;
4356 * Wait for a BIO to finish.
4359 biowait(struct bio *bp, const char *wchan)
4363 mtxp = mtx_pool_find(mtxpool_sleep, bp);
4365 while ((bp->bio_flags & BIO_DONE) == 0)
4366 msleep(bp, mtxp, PRIBIO, wchan, 0);
4368 if (bp->bio_error != 0)
4369 return (bp->bio_error);
4370 if (!(bp->bio_flags & BIO_ERROR))
4376 biofinish(struct bio *bp, struct devstat *stat, int error)
4380 bp->bio_error = error;
4381 bp->bio_flags |= BIO_ERROR;
4384 devstat_end_transaction_bio(stat, bp);
4388 #if defined(BUF_TRACKING) || defined(FULL_BUF_TRACKING)
4390 biotrack_buf(struct bio *bp, const char *location)
4393 buf_track(bp->bio_track_bp, location);
4400 * Wait for buffer I/O completion, returning error status. The buffer
4401 * is left locked and B_DONE on return. B_EINTR is converted into an EINTR
4402 * error and cleared.
4405 bufwait(struct buf *bp)
4407 if (bp->b_iocmd == BIO_READ)
4408 bwait(bp, PRIBIO, "biord");
4410 bwait(bp, PRIBIO, "biowr");
4411 if (bp->b_flags & B_EINTR) {
4412 bp->b_flags &= ~B_EINTR;
4415 if (bp->b_ioflags & BIO_ERROR) {
4416 return (bp->b_error ? bp->b_error : EIO);
4425 * Finish I/O on a buffer, optionally calling a completion function.
4426 * This is usually called from an interrupt so process blocking is
4429 * biodone is also responsible for setting B_CACHE in a B_VMIO bp.
4430 * In a non-VMIO bp, B_CACHE will be set on the next getblk()
4431 * assuming B_INVAL is clear.
4433 * For the VMIO case, we set B_CACHE if the op was a read and no
4434 * read error occurred, or if the op was a write. B_CACHE is never
4435 * set if the buffer is invalid or otherwise uncacheable.
4437 * biodone does not mess with B_INVAL, allowing the I/O routine or the
4438 * initiator to leave B_INVAL set to brelse the buffer out of existence
4439 * in the biodone routine.
4442 bufdone(struct buf *bp)
4444 struct bufobj *dropobj;
4445 void (*biodone)(struct buf *);
4447 buf_track(bp, __func__);
4448 CTR3(KTR_BUF, "bufdone(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
4451 KASSERT(!(bp->b_flags & B_DONE), ("biodone: bp %p already done", bp));
4452 BUF_ASSERT_HELD(bp);
4454 runningbufwakeup(bp);
4455 if (bp->b_iocmd == BIO_WRITE)
4456 dropobj = bp->b_bufobj;
4457 /* call optional completion function if requested */
4458 if (bp->b_iodone != NULL) {
4459 biodone = bp->b_iodone;
4460 bp->b_iodone = NULL;
4463 bufobj_wdrop(dropobj);
4466 if (bp->b_flags & B_VMIO) {
4468 * Set B_CACHE if the op was a normal read and no error
4469 * occurred. B_CACHE is set for writes in the b*write()
4472 if (bp->b_iocmd == BIO_READ &&
4473 !(bp->b_flags & (B_INVAL|B_NOCACHE)) &&
4474 !(bp->b_ioflags & BIO_ERROR))
4475 bp->b_flags |= B_CACHE;
4476 vfs_vmio_iodone(bp);
4478 if (!LIST_EMPTY(&bp->b_dep))
4480 if ((bp->b_flags & B_CKHASH) != 0) {
4481 KASSERT(bp->b_iocmd == BIO_READ,
4482 ("bufdone: b_iocmd %d not BIO_READ", bp->b_iocmd));
4483 KASSERT(buf_mapped(bp), ("bufdone: bp %p not mapped", bp));
4484 (*bp->b_ckhashcalc)(bp);
4487 * For asynchronous completions, release the buffer now. The brelse
4488 * will do a wakeup there if necessary - so no need to do a wakeup
4489 * here in the async case. The sync case always needs to do a wakeup.
4491 if (bp->b_flags & B_ASYNC) {
4492 if ((bp->b_flags & (B_NOCACHE | B_INVAL | B_RELBUF)) ||
4493 (bp->b_ioflags & BIO_ERROR))
4500 bufobj_wdrop(dropobj);
4504 * This routine is called in lieu of iodone in the case of
4505 * incomplete I/O. This keeps the busy status for pages
4509 vfs_unbusy_pages(struct buf *bp)
4515 runningbufwakeup(bp);
4516 if (!(bp->b_flags & B_VMIO))
4519 obj = bp->b_bufobj->bo_object;
4520 VM_OBJECT_WLOCK(obj);
4521 for (i = 0; i < bp->b_npages; i++) {
4523 if (m == bogus_page) {
4524 m = vm_page_lookup(obj, OFF_TO_IDX(bp->b_offset) + i);
4526 panic("vfs_unbusy_pages: page missing\n");
4528 if (buf_mapped(bp)) {
4529 BUF_CHECK_MAPPED(bp);
4530 pmap_qenter(trunc_page((vm_offset_t)bp->b_data),
4531 bp->b_pages, bp->b_npages);
4533 BUF_CHECK_UNMAPPED(bp);
4537 vm_object_pip_wakeupn(obj, bp->b_npages);
4538 VM_OBJECT_WUNLOCK(obj);
4542 * vfs_page_set_valid:
4544 * Set the valid bits in a page based on the supplied offset. The
4545 * range is restricted to the buffer's size.
4547 * This routine is typically called after a read completes.
4550 vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, vm_page_t m)
4555 * Compute the end offset, eoff, such that [off, eoff) does not span a
4556 * page boundary and eoff is not greater than the end of the buffer.
4557 * The end of the buffer, in this case, is our file EOF, not the
4558 * allocation size of the buffer.
4560 eoff = (off + PAGE_SIZE) & ~(vm_ooffset_t)PAGE_MASK;
4561 if (eoff > bp->b_offset + bp->b_bcount)
4562 eoff = bp->b_offset + bp->b_bcount;
4565 * Set valid range. This is typically the entire buffer and thus the
4569 vm_page_set_valid_range(m, off & PAGE_MASK, eoff - off);
4573 * vfs_page_set_validclean:
4575 * Set the valid bits and clear the dirty bits in a page based on the
4576 * supplied offset. The range is restricted to the buffer's size.
4579 vfs_page_set_validclean(struct buf *bp, vm_ooffset_t off, vm_page_t m)
4581 vm_ooffset_t soff, eoff;
4584 * Start and end offsets in buffer. eoff - soff may not cross a
4585 * page boundary or cross the end of the buffer. The end of the
4586 * buffer, in this case, is our file EOF, not the allocation size
4590 eoff = (off + PAGE_SIZE) & ~(off_t)PAGE_MASK;
4591 if (eoff > bp->b_offset + bp->b_bcount)
4592 eoff = bp->b_offset + bp->b_bcount;
4595 * Set valid range. This is typically the entire buffer and thus the
4599 vm_page_set_validclean(
4601 (vm_offset_t) (soff & PAGE_MASK),
4602 (vm_offset_t) (eoff - soff)
4608 * Ensure that all buffer pages are not exclusive busied. If any page is
4609 * exclusive busy, drain it.
4612 vfs_drain_busy_pages(struct buf *bp)
4617 VM_OBJECT_ASSERT_WLOCKED(bp->b_bufobj->bo_object);
4619 for (i = 0; i < bp->b_npages; i++) {
4621 if (vm_page_xbusied(m)) {
4622 for (; last_busied < i; last_busied++)
4623 vm_page_sbusy(bp->b_pages[last_busied]);
4624 while (vm_page_xbusied(m)) {
4626 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object);
4627 vm_page_busy_sleep(m, "vbpage", true);
4628 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object);
4632 for (i = 0; i < last_busied; i++)
4633 vm_page_sunbusy(bp->b_pages[i]);
4637 * This routine is called before a device strategy routine.
4638 * It is used to tell the VM system that paging I/O is in
4639 * progress, and treat the pages associated with the buffer
4640 * almost as being exclusive busy. Also the object paging_in_progress
4641 * flag is handled to make sure that the object doesn't become
4644 * Since I/O has not been initiated yet, certain buffer flags
4645 * such as BIO_ERROR or B_INVAL may be in an inconsistent state
4646 * and should be ignored.
4649 vfs_busy_pages(struct buf *bp, int clear_modify)
4657 if (!(bp->b_flags & B_VMIO))
4660 obj = bp->b_bufobj->bo_object;
4661 foff = bp->b_offset;
4662 KASSERT(bp->b_offset != NOOFFSET,
4663 ("vfs_busy_pages: no buffer offset"));
4664 VM_OBJECT_WLOCK(obj);
4665 vfs_drain_busy_pages(bp);
4666 if (bp->b_bufsize != 0)
4667 vfs_setdirty_locked_object(bp);
4669 for (i = 0; i < bp->b_npages; i++) {
4672 if ((bp->b_flags & B_CLUSTER) == 0) {
4673 vm_object_pip_add(obj, 1);
4677 * When readying a buffer for a read ( i.e
4678 * clear_modify == 0 ), it is important to do
4679 * bogus_page replacement for valid pages in
4680 * partially instantiated buffers. Partially
4681 * instantiated buffers can, in turn, occur when
4682 * reconstituting a buffer from its VM backing store
4683 * base. We only have to do this if B_CACHE is
4684 * clear ( which causes the I/O to occur in the
4685 * first place ). The replacement prevents the read
4686 * I/O from overwriting potentially dirty VM-backed
4687 * pages. XXX bogus page replacement is, uh, bogus.
4688 * It may not work properly with small-block devices.
4689 * We need to find a better way.
4692 pmap_remove_write(m);
4693 vfs_page_set_validclean(bp, foff, m);
4694 } else if (m->valid == VM_PAGE_BITS_ALL &&
4695 (bp->b_flags & B_CACHE) == 0) {
4696 bp->b_pages[i] = bogus_page;
4699 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK;
4701 VM_OBJECT_WUNLOCK(obj);
4702 if (bogus && buf_mapped(bp)) {
4703 BUF_CHECK_MAPPED(bp);
4704 pmap_qenter(trunc_page((vm_offset_t)bp->b_data),
4705 bp->b_pages, bp->b_npages);
4710 * vfs_bio_set_valid:
4712 * Set the range within the buffer to valid. The range is
4713 * relative to the beginning of the buffer, b_offset. Note that
4714 * b_offset itself may be offset from the beginning of the first
4718 vfs_bio_set_valid(struct buf *bp, int base, int size)
4723 if (!(bp->b_flags & B_VMIO))
4727 * Fixup base to be relative to beginning of first page.
4728 * Set initial n to be the maximum number of bytes in the
4729 * first page that can be validated.
4731 base += (bp->b_offset & PAGE_MASK);
4732 n = PAGE_SIZE - (base & PAGE_MASK);
4734 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object);
4735 for (i = base / PAGE_SIZE; size > 0 && i < bp->b_npages; ++i) {
4739 vm_page_set_valid_range(m, base & PAGE_MASK, n);
4744 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object);
4750 * If the specified buffer is a non-VMIO buffer, clear the entire
4751 * buffer. If the specified buffer is a VMIO buffer, clear and
4752 * validate only the previously invalid portions of the buffer.
4753 * This routine essentially fakes an I/O, so we need to clear
4754 * BIO_ERROR and B_INVAL.
4756 * Note that while we only theoretically need to clear through b_bcount,
4757 * we go ahead and clear through b_bufsize.
4760 vfs_bio_clrbuf(struct buf *bp)
4762 int i, j, mask, sa, ea, slide;
4764 if ((bp->b_flags & (B_VMIO | B_MALLOC)) != B_VMIO) {
4768 bp->b_flags &= ~B_INVAL;
4769 bp->b_ioflags &= ~BIO_ERROR;
4770 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object);
4771 if ((bp->b_npages == 1) && (bp->b_bufsize < PAGE_SIZE) &&
4772 (bp->b_offset & PAGE_MASK) == 0) {
4773 if (bp->b_pages[0] == bogus_page)
4775 mask = (1 << (bp->b_bufsize / DEV_BSIZE)) - 1;
4776 VM_OBJECT_ASSERT_WLOCKED(bp->b_pages[0]->object);
4777 if ((bp->b_pages[0]->valid & mask) == mask)
4779 if ((bp->b_pages[0]->valid & mask) == 0) {
4780 pmap_zero_page_area(bp->b_pages[0], 0, bp->b_bufsize);
4781 bp->b_pages[0]->valid |= mask;
4785 sa = bp->b_offset & PAGE_MASK;
4787 for (i = 0; i < bp->b_npages; i++, sa = 0) {
4788 slide = imin(slide + PAGE_SIZE, bp->b_offset + bp->b_bufsize);
4789 ea = slide & PAGE_MASK;
4792 if (bp->b_pages[i] == bogus_page)
4795 mask = ((1 << ((ea - sa) / DEV_BSIZE)) - 1) << j;
4796 VM_OBJECT_ASSERT_WLOCKED(bp->b_pages[i]->object);
4797 if ((bp->b_pages[i]->valid & mask) == mask)
4799 if ((bp->b_pages[i]->valid & mask) == 0)
4800 pmap_zero_page_area(bp->b_pages[i], sa, ea - sa);
4802 for (; sa < ea; sa += DEV_BSIZE, j++) {
4803 if ((bp->b_pages[i]->valid & (1 << j)) == 0) {
4804 pmap_zero_page_area(bp->b_pages[i],
4809 bp->b_pages[i]->valid |= mask;
4812 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object);
4817 vfs_bio_bzero_buf(struct buf *bp, int base, int size)
4822 if (buf_mapped(bp)) {
4823 BUF_CHECK_MAPPED(bp);
4824 bzero(bp->b_data + base, size);
4826 BUF_CHECK_UNMAPPED(bp);
4827 n = PAGE_SIZE - (base & PAGE_MASK);
4828 for (i = base / PAGE_SIZE; size > 0 && i < bp->b_npages; ++i) {
4832 pmap_zero_page_area(m, base & PAGE_MASK, n);
4841 * Update buffer flags based on I/O request parameters, optionally releasing the
4842 * buffer. If it's VMIO or direct I/O, the buffer pages are released to the VM,
4843 * where they may be placed on a page queue (VMIO) or freed immediately (direct
4844 * I/O). Otherwise the buffer is released to the cache.
4847 b_io_dismiss(struct buf *bp, int ioflag, bool release)
4850 KASSERT((ioflag & IO_NOREUSE) == 0 || (ioflag & IO_VMIO) != 0,
4851 ("buf %p non-VMIO noreuse", bp));
4853 if ((ioflag & IO_DIRECT) != 0)
4854 bp->b_flags |= B_DIRECT;
4855 if ((ioflag & (IO_VMIO | IO_DIRECT)) != 0 && LIST_EMPTY(&bp->b_dep)) {
4856 bp->b_flags |= B_RELBUF;
4857 if ((ioflag & IO_NOREUSE) != 0)
4858 bp->b_flags |= B_NOREUSE;
4866 vfs_bio_brelse(struct buf *bp, int ioflag)
4869 b_io_dismiss(bp, ioflag, true);
4873 vfs_bio_set_flags(struct buf *bp, int ioflag)
4876 b_io_dismiss(bp, ioflag, false);
4880 * vm_hold_load_pages and vm_hold_free_pages get pages into
4881 * a buffers address space. The pages are anonymous and are
4882 * not associated with a file object.
4885 vm_hold_load_pages(struct buf *bp, vm_offset_t from, vm_offset_t to)
4891 BUF_CHECK_MAPPED(bp);
4893 to = round_page(to);
4894 from = round_page(from);
4895 index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT;
4897 for (pg = from; pg < to; pg += PAGE_SIZE, index++) {
4899 * note: must allocate system pages since blocking here
4900 * could interfere with paging I/O, no matter which
4903 p = vm_page_alloc(NULL, 0, VM_ALLOC_SYSTEM | VM_ALLOC_NOOBJ |
4904 VM_ALLOC_WIRED | VM_ALLOC_COUNT((to - pg) >> PAGE_SHIFT) |
4906 pmap_qenter(pg, &p, 1);
4907 bp->b_pages[index] = p;
4909 bp->b_npages = index;
4912 /* Return pages associated with this buf to the vm system */
4914 vm_hold_free_pages(struct buf *bp, int newbsize)
4918 int index, newnpages;
4920 BUF_CHECK_MAPPED(bp);
4922 from = round_page((vm_offset_t)bp->b_data + newbsize);
4923 newnpages = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT;
4924 if (bp->b_npages > newnpages)
4925 pmap_qremove(from, bp->b_npages - newnpages);
4926 for (index = newnpages; index < bp->b_npages; index++) {
4927 p = bp->b_pages[index];
4928 bp->b_pages[index] = NULL;
4932 vm_wire_sub(bp->b_npages - newnpages);
4933 bp->b_npages = newnpages;
4937 * Map an IO request into kernel virtual address space.
4939 * All requests are (re)mapped into kernel VA space.
4940 * Notice that we use b_bufsize for the size of the buffer
4941 * to be mapped. b_bcount might be modified by the driver.
4943 * Note that even if the caller determines that the address space should
4944 * be valid, a race or a smaller-file mapped into a larger space may
4945 * actually cause vmapbuf() to fail, so all callers of vmapbuf() MUST
4946 * check the return value.
4948 * This function only works with pager buffers.
4951 vmapbuf(struct buf *bp, int mapbuf)
4956 if (bp->b_bufsize < 0)
4958 prot = VM_PROT_READ;
4959 if (bp->b_iocmd == BIO_READ)
4960 prot |= VM_PROT_WRITE; /* Less backwards than it looks */
4961 if ((pidx = vm_fault_quick_hold_pages(&curproc->p_vmspace->vm_map,
4962 (vm_offset_t)bp->b_data, bp->b_bufsize, prot, bp->b_pages,
4963 btoc(MAXPHYS))) < 0)
4965 bp->b_npages = pidx;
4966 bp->b_offset = ((vm_offset_t)bp->b_data) & PAGE_MASK;
4967 if (mapbuf || !unmapped_buf_allowed) {
4968 pmap_qenter((vm_offset_t)bp->b_kvabase, bp->b_pages, pidx);
4969 bp->b_data = bp->b_kvabase + bp->b_offset;
4971 bp->b_data = unmapped_buf;
4976 * Free the io map PTEs associated with this IO operation.
4977 * We also invalidate the TLB entries and restore the original b_addr.
4979 * This function only works with pager buffers.
4982 vunmapbuf(struct buf *bp)
4986 npages = bp->b_npages;
4988 pmap_qremove(trunc_page((vm_offset_t)bp->b_data), npages);
4989 vm_page_unhold_pages(bp->b_pages, npages);
4991 bp->b_data = unmapped_buf;
4995 bdone(struct buf *bp)
4999 mtxp = mtx_pool_find(mtxpool_sleep, bp);
5001 bp->b_flags |= B_DONE;
5007 bwait(struct buf *bp, u_char pri, const char *wchan)
5011 mtxp = mtx_pool_find(mtxpool_sleep, bp);
5013 while ((bp->b_flags & B_DONE) == 0)
5014 msleep(bp, mtxp, pri, wchan, 0);
5019 bufsync(struct bufobj *bo, int waitfor)
5022 return (VOP_FSYNC(bo2vnode(bo), waitfor, curthread));
5026 bufstrategy(struct bufobj *bo, struct buf *bp)
5032 KASSERT(vp == bo->bo_private, ("Inconsistent vnode bufstrategy"));
5033 KASSERT(vp->v_type != VCHR && vp->v_type != VBLK,
5034 ("Wrong vnode in bufstrategy(bp=%p, vp=%p)", bp, vp));
5035 i = VOP_STRATEGY(vp, bp);
5036 KASSERT(i == 0, ("VOP_STRATEGY failed bp=%p vp=%p", bp, bp->b_vp));
5040 * Initialize a struct bufobj before use. Memory is assumed zero filled.
5043 bufobj_init(struct bufobj *bo, void *private)
5045 static volatile int bufobj_cleanq;
5048 atomic_fetchadd_int(&bufobj_cleanq, 1) % buf_domains;
5049 rw_init(BO_LOCKPTR(bo), "bufobj interlock");
5050 bo->bo_private = private;
5051 TAILQ_INIT(&bo->bo_clean.bv_hd);
5052 TAILQ_INIT(&bo->bo_dirty.bv_hd);
5056 bufobj_wrefl(struct bufobj *bo)
5059 KASSERT(bo != NULL, ("NULL bo in bufobj_wref"));
5060 ASSERT_BO_WLOCKED(bo);
5065 bufobj_wref(struct bufobj *bo)
5068 KASSERT(bo != NULL, ("NULL bo in bufobj_wref"));
5075 bufobj_wdrop(struct bufobj *bo)
5078 KASSERT(bo != NULL, ("NULL bo in bufobj_wdrop"));
5080 KASSERT(bo->bo_numoutput > 0, ("bufobj_wdrop non-positive count"));
5081 if ((--bo->bo_numoutput == 0) && (bo->bo_flag & BO_WWAIT)) {
5082 bo->bo_flag &= ~BO_WWAIT;
5083 wakeup(&bo->bo_numoutput);
5089 bufobj_wwait(struct bufobj *bo, int slpflag, int timeo)
5093 KASSERT(bo != NULL, ("NULL bo in bufobj_wwait"));
5094 ASSERT_BO_WLOCKED(bo);
5096 while (bo->bo_numoutput) {
5097 bo->bo_flag |= BO_WWAIT;
5098 error = msleep(&bo->bo_numoutput, BO_LOCKPTR(bo),
5099 slpflag | (PRIBIO + 1), "bo_wwait", timeo);
5107 * Set bio_data or bio_ma for struct bio from the struct buf.
5110 bdata2bio(struct buf *bp, struct bio *bip)
5113 if (!buf_mapped(bp)) {
5114 KASSERT(unmapped_buf_allowed, ("unmapped"));
5115 bip->bio_ma = bp->b_pages;
5116 bip->bio_ma_n = bp->b_npages;
5117 bip->bio_data = unmapped_buf;
5118 bip->bio_ma_offset = (vm_offset_t)bp->b_offset & PAGE_MASK;
5119 bip->bio_flags |= BIO_UNMAPPED;
5120 KASSERT(round_page(bip->bio_ma_offset + bip->bio_length) /
5121 PAGE_SIZE == bp->b_npages,
5122 ("Buffer %p too short: %d %lld %d", bp, bip->bio_ma_offset,
5123 (long long)bip->bio_length, bip->bio_ma_n));
5125 bip->bio_data = bp->b_data;
5131 * The MIPS pmap code currently doesn't handle aliased pages.
5132 * The VIPT caches may not handle page aliasing themselves, leading
5133 * to data corruption.
5135 * As such, this code makes a system extremely unhappy if said
5136 * system doesn't support unaliasing the above situation in hardware.
5137 * Some "recent" systems (eg some mips24k/mips74k cores) don't enable
5138 * this feature at build time, so it has to be handled in software.
5140 * Once the MIPS pmap/cache code grows to support this function on
5141 * earlier chips, it should be flipped back off.
5144 static int buf_pager_relbuf = 1;
5146 static int buf_pager_relbuf = 0;
5148 SYSCTL_INT(_vfs, OID_AUTO, buf_pager_relbuf, CTLFLAG_RWTUN,
5149 &buf_pager_relbuf, 0,
5150 "Make buffer pager release buffers after reading");
5153 * The buffer pager. It uses buffer reads to validate pages.
5155 * In contrast to the generic local pager from vm/vnode_pager.c, this
5156 * pager correctly and easily handles volumes where the underlying
5157 * device block size is greater than the machine page size. The
5158 * buffer cache transparently extends the requested page run to be
5159 * aligned at the block boundary, and does the necessary bogus page
5160 * replacements in the addends to avoid obliterating already valid
5163 * The only non-trivial issue is that the exclusive busy state for
5164 * pages, which is assumed by the vm_pager_getpages() interface, is
5165 * incompatible with the VMIO buffer cache's desire to share-busy the
5166 * pages. This function performs a trivial downgrade of the pages'
5167 * state before reading buffers, and a less trivial upgrade from the
5168 * shared-busy to excl-busy state after the read.
5171 vfs_bio_getpages(struct vnode *vp, vm_page_t *ma, int count,
5172 int *rbehind, int *rahead, vbg_get_lblkno_t get_lblkno,
5173 vbg_get_blksize_t get_blksize)
5180 vm_ooffset_t la, lb, poff, poffe;
5182 int bo_bs, br_flags, error, i, pgsin, pgsin_a, pgsin_b;
5185 object = vp->v_object;
5188 la = IDX_TO_OFF(ma[count - 1]->pindex);
5189 if (la >= object->un_pager.vnp.vnp_size)
5190 return (VM_PAGER_BAD);
5193 * Change the meaning of la from where the last requested page starts
5194 * to where it ends, because that's the end of the requested region
5195 * and the start of the potential read-ahead region.
5198 lpart = la > object->un_pager.vnp.vnp_size;
5199 bo_bs = get_blksize(vp, get_lblkno(vp, IDX_TO_OFF(ma[0]->pindex)));
5202 * Calculate read-ahead, behind and total pages.
5205 lb = IDX_TO_OFF(ma[0]->pindex);
5206 pgsin_b = OFF_TO_IDX(lb - rounddown2(lb, bo_bs));
5208 if (rbehind != NULL)
5210 pgsin_a = OFF_TO_IDX(roundup2(la, bo_bs) - la);
5211 if (la + IDX_TO_OFF(pgsin_a) >= object->un_pager.vnp.vnp_size)
5212 pgsin_a = OFF_TO_IDX(roundup2(object->un_pager.vnp.vnp_size,
5217 VM_CNT_INC(v_vnodein);
5218 VM_CNT_ADD(v_vnodepgsin, pgsin);
5220 br_flags = (mp != NULL && (mp->mnt_kern_flag & MNTK_UNMAPPED_BUFS)
5221 != 0) ? GB_UNMAPPED : 0;
5222 VM_OBJECT_WLOCK(object);
5224 for (i = 0; i < count; i++)
5225 vm_page_busy_downgrade(ma[i]);
5226 VM_OBJECT_WUNLOCK(object);
5229 for (i = 0; i < count; i++) {
5233 * Pages are shared busy and the object lock is not
5234 * owned, which together allow for the pages'
5235 * invalidation. The racy test for validity avoids
5236 * useless creation of the buffer for the most typical
5237 * case when invalidation is not used in redo or for
5238 * parallel read. The shared->excl upgrade loop at
5239 * the end of the function catches the race in a
5240 * reliable way (protected by the object lock).
5242 if (m->valid == VM_PAGE_BITS_ALL)
5245 poff = IDX_TO_OFF(m->pindex);
5246 poffe = MIN(poff + PAGE_SIZE, object->un_pager.vnp.vnp_size);
5247 for (; poff < poffe; poff += bsize) {
5248 lbn = get_lblkno(vp, poff);
5253 bsize = get_blksize(vp, lbn);
5254 error = bread_gb(vp, lbn, bsize, curthread->td_ucred,
5258 if (LIST_EMPTY(&bp->b_dep)) {
5260 * Invalidation clears m->valid, but
5261 * may leave B_CACHE flag if the
5262 * buffer existed at the invalidation
5263 * time. In this case, recycle the
5264 * buffer to do real read on next
5265 * bread() after redo.
5267 * Otherwise B_RELBUF is not strictly
5268 * necessary, enable to reduce buf
5271 if (buf_pager_relbuf ||
5272 m->valid != VM_PAGE_BITS_ALL)
5273 bp->b_flags |= B_RELBUF;
5275 bp->b_flags &= ~B_NOCACHE;
5281 KASSERT(1 /* racy, enable for debugging */ ||
5282 m->valid == VM_PAGE_BITS_ALL || i == count - 1,
5283 ("buf %d %p invalid", i, m));
5284 if (i == count - 1 && lpart) {
5285 VM_OBJECT_WLOCK(object);
5286 if (m->valid != 0 &&
5287 m->valid != VM_PAGE_BITS_ALL)
5288 vm_page_zero_invalid(m, TRUE);
5289 VM_OBJECT_WUNLOCK(object);
5295 VM_OBJECT_WLOCK(object);
5297 for (i = 0; i < count; i++) {
5298 vm_page_sunbusy(ma[i]);
5299 ma[i] = vm_page_grab(object, ma[i]->pindex, VM_ALLOC_NORMAL);
5302 * Since the pages were only sbusy while neither the
5303 * buffer nor the object lock was held by us, or
5304 * reallocated while vm_page_grab() slept for busy
5305 * relinguish, they could have been invalidated.
5306 * Recheck the valid bits and re-read as needed.
5308 * Note that the last page is made fully valid in the
5309 * read loop, and partial validity for the page at
5310 * index count - 1 could mean that the page was
5311 * invalidated or removed, so we must restart for
5314 if (ma[i]->valid != VM_PAGE_BITS_ALL)
5317 if (redo && error == 0)
5319 VM_OBJECT_WUNLOCK(object);
5320 return (error != 0 ? VM_PAGER_ERROR : VM_PAGER_OK);
5323 #include "opt_ddb.h"
5325 #include <ddb/ddb.h>
5327 /* DDB command to show buffer data */
5328 DB_SHOW_COMMAND(buffer, db_show_buffer)
5331 struct buf *bp = (struct buf *)addr;
5332 #ifdef FULL_BUF_TRACKING
5337 db_printf("usage: show buffer <addr>\n");
5341 db_printf("buf at %p\n", bp);
5342 db_printf("b_flags = 0x%b, b_xflags=0x%b, b_vflags=0x%b\n",
5343 (u_int)bp->b_flags, PRINT_BUF_FLAGS, (u_int)bp->b_xflags,
5344 PRINT_BUF_XFLAGS, (u_int)bp->b_vflags, PRINT_BUF_VFLAGS);
5346 "b_error = %d, b_bufsize = %ld, b_bcount = %ld, b_resid = %ld\n"
5347 "b_bufobj = (%p), b_data = %p, b_blkno = %jd, b_lblkno = %jd, "
5349 bp->b_error, bp->b_bufsize, bp->b_bcount, bp->b_resid,
5350 bp->b_bufobj, bp->b_data, (intmax_t)bp->b_blkno,
5351 (intmax_t)bp->b_lblkno, bp->b_dep.lh_first);
5352 db_printf("b_kvabase = %p, b_kvasize = %d\n",
5353 bp->b_kvabase, bp->b_kvasize);
5356 db_printf("b_npages = %d, pages(OBJ, IDX, PA): ", bp->b_npages);
5357 for (i = 0; i < bp->b_npages; i++) {
5361 db_printf("(%p, 0x%lx, 0x%lx)", m->object,
5363 (u_long)VM_PAGE_TO_PHYS(m));
5365 db_printf("( ??? )");
5366 if ((i + 1) < bp->b_npages)
5371 BUF_LOCKPRINTINFO(bp);
5372 #if defined(FULL_BUF_TRACKING)
5373 db_printf("b_io_tracking: b_io_tcnt = %u\n", bp->b_io_tcnt);
5375 i = bp->b_io_tcnt % BUF_TRACKING_SIZE;
5376 for (j = 1; j <= BUF_TRACKING_SIZE; j++) {
5377 if (bp->b_io_tracking[BUF_TRACKING_ENTRY(i - j)] == NULL)
5379 db_printf(" %2u: %s\n", j,
5380 bp->b_io_tracking[BUF_TRACKING_ENTRY(i - j)]);
5382 #elif defined(BUF_TRACKING)
5383 db_printf("b_io_tracking: %s\n", bp->b_io_tracking);
5388 DB_SHOW_COMMAND(bufqueues, bufqueues)
5390 struct bufdomain *bd;
5395 db_printf("bqempty: %d\n", bqempty.bq_len);
5397 for (i = 0; i < buf_domains; i++) {
5399 db_printf("Buf domain %d\n", i);
5400 db_printf("\tfreebufs\t%d\n", bd->bd_freebuffers);
5401 db_printf("\tlofreebufs\t%d\n", bd->bd_lofreebuffers);
5402 db_printf("\thifreebufs\t%d\n", bd->bd_hifreebuffers);
5404 db_printf("\tbufspace\t%ld\n", bd->bd_bufspace);
5405 db_printf("\tmaxbufspace\t%ld\n", bd->bd_maxbufspace);
5406 db_printf("\thibufspace\t%ld\n", bd->bd_hibufspace);
5407 db_printf("\tlobufspace\t%ld\n", bd->bd_lobufspace);
5408 db_printf("\tbufspacethresh\t%ld\n", bd->bd_bufspacethresh);
5410 db_printf("\tnumdirtybuffers\t%d\n", bd->bd_numdirtybuffers);
5411 db_printf("\tlodirtybuffers\t%d\n", bd->bd_lodirtybuffers);
5412 db_printf("\thidirtybuffers\t%d\n", bd->bd_hidirtybuffers);
5413 db_printf("\tdirtybufthresh\t%d\n", bd->bd_dirtybufthresh);
5416 TAILQ_FOREACH(bp, &bd->bd_cleanq->bq_queue, b_freelist)
5417 total += bp->b_bufsize;
5418 db_printf("\tcleanq count\t%d (%ld)\n",
5419 bd->bd_cleanq->bq_len, total);
5421 TAILQ_FOREACH(bp, &bd->bd_dirtyq.bq_queue, b_freelist)
5422 total += bp->b_bufsize;
5423 db_printf("\tdirtyq count\t%d (%ld)\n",
5424 bd->bd_dirtyq.bq_len, total);
5425 db_printf("\twakeup\t\t%d\n", bd->bd_wanted);
5426 db_printf("\tlim\t\t%d\n", bd->bd_lim);
5427 db_printf("\tCPU ");
5428 for (j = 0; j <= mp_maxid; j++)
5429 db_printf("%d, ", bd->bd_subq[j].bq_len);
5433 for (j = 0; j < nbuf; j++)
5434 if (buf[j].b_domain == i && BUF_ISLOCKED(&buf[j])) {
5436 total += buf[j].b_bufsize;
5438 db_printf("\tLocked buffers: %d space %ld\n", cnt, total);
5441 for (j = 0; j < nbuf; j++)
5442 if (buf[j].b_domain == i) {
5444 total += buf[j].b_bufsize;
5446 db_printf("\tTotal buffers: %d space %ld\n", cnt, total);
5450 DB_SHOW_COMMAND(lockedbufs, lockedbufs)
5455 for (i = 0; i < nbuf; i++) {
5457 if (BUF_ISLOCKED(bp)) {
5458 db_show_buffer((uintptr_t)bp, 1, 0, NULL);
5466 DB_SHOW_COMMAND(vnodebufs, db_show_vnodebufs)
5472 db_printf("usage: show vnodebufs <addr>\n");
5475 vp = (struct vnode *)addr;
5476 db_printf("Clean buffers:\n");
5477 TAILQ_FOREACH(bp, &vp->v_bufobj.bo_clean.bv_hd, b_bobufs) {
5478 db_show_buffer((uintptr_t)bp, 1, 0, NULL);
5481 db_printf("Dirty buffers:\n");
5482 TAILQ_FOREACH(bp, &vp->v_bufobj.bo_dirty.bv_hd, b_bobufs) {
5483 db_show_buffer((uintptr_t)bp, 1, 0, NULL);
5488 DB_COMMAND(countfreebufs, db_coundfreebufs)
5491 int i, used = 0, nfree = 0;
5494 db_printf("usage: countfreebufs\n");
5498 for (i = 0; i < nbuf; i++) {
5500 if (bp->b_qindex == QUEUE_EMPTY)
5506 db_printf("Counted %d free, %d used (%d tot)\n", nfree, used,
5508 db_printf("numfreebuffers is %d\n", numfreebuffers);