2 * Copyright (c) 2004 Poul-Henning Kamp
3 * Copyright (c) 1994,1997 John S. Dyson
4 * Copyright (c) 2013 The FreeBSD Foundation
7 * Portions of this software were developed by Konstantin Belousov
8 * under sponsorship from the FreeBSD Foundation.
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in the
17 * documentation and/or other materials provided with the distribution.
19 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
22 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
33 * this file contains a new buffer I/O scheme implementing a coherent
34 * VM object and buffer cache scheme. Pains have been taken to make
35 * sure that the performance degradation associated with schemes such
36 * as this is not realized.
38 * Author: John S. Dyson
39 * Significant help during the development and debugging phases
40 * had been provided by David Greenman, also of the FreeBSD core team.
42 * see man buf(9) for more info.
45 #include <sys/cdefs.h>
46 __FBSDID("$FreeBSD$");
48 #include <sys/param.h>
49 #include <sys/systm.h>
53 #include <sys/devicestat.h>
54 #include <sys/eventhandler.h>
56 #include <sys/limits.h>
58 #include <sys/malloc.h>
59 #include <sys/mount.h>
60 #include <sys/mutex.h>
61 #include <sys/kernel.h>
62 #include <sys/kthread.h>
64 #include <sys/resourcevar.h>
65 #include <sys/rwlock.h>
66 #include <sys/sysctl.h>
68 #include <sys/vmmeter.h>
69 #include <sys/vnode.h>
70 #include <geom/geom.h>
72 #include <vm/vm_param.h>
73 #include <vm/vm_kern.h>
74 #include <vm/vm_pageout.h>
75 #include <vm/vm_page.h>
76 #include <vm/vm_object.h>
77 #include <vm/vm_extern.h>
78 #include <vm/vm_map.h>
79 #include "opt_compat.h"
82 static MALLOC_DEFINE(M_BIOBUF, "biobuf", "BIO buffer");
84 struct bio_ops bioops; /* I/O operation notification */
86 struct buf_ops buf_ops_bio = {
87 .bop_name = "buf_ops_bio",
88 .bop_write = bufwrite,
89 .bop_strategy = bufstrategy,
91 .bop_bdflush = bufbdflush,
95 * XXX buf is global because kern_shutdown.c and ffs_checkoverlap has
96 * carnal knowledge of buffers. This knowledge should be moved to vfs_bio.c.
98 struct buf *buf; /* buffer header pool */
101 /* Used below and for softdep flushing threads in ufs/ffs/ffs_softdep.c */
102 struct proc *bufdaemonproc;
104 static int inmem(struct vnode *vp, daddr_t blkno);
105 static void vm_hold_free_pages(struct buf *bp, int newbsize);
106 static void vm_hold_load_pages(struct buf *bp, vm_offset_t from,
108 static void vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, vm_page_t m);
109 static void vfs_page_set_validclean(struct buf *bp, vm_ooffset_t off,
111 static void vfs_clean_pages_dirty_buf(struct buf *bp);
112 static void vfs_setdirty_locked_object(struct buf *bp);
113 static void vfs_vmio_release(struct buf *bp);
114 static int vfs_bio_clcheck(struct vnode *vp, int size,
115 daddr_t lblkno, daddr_t blkno);
116 static int buf_flush(int);
117 static int flushbufqueues(int, int);
118 static void buf_daemon(void);
119 static void bremfreel(struct buf *bp);
120 static __inline void bd_wakeup(void);
121 static int sysctl_runningspace(SYSCTL_HANDLER_ARGS);
122 #if defined(COMPAT_FREEBSD4) || defined(COMPAT_FREEBSD5) || \
123 defined(COMPAT_FREEBSD6) || defined(COMPAT_FREEBSD7)
124 static int sysctl_bufspace(SYSCTL_HANDLER_ARGS);
127 int vmiodirenable = TRUE;
128 SYSCTL_INT(_vfs, OID_AUTO, vmiodirenable, CTLFLAG_RW, &vmiodirenable, 0,
129 "Use the VM system for directory writes");
130 long runningbufspace;
131 SYSCTL_LONG(_vfs, OID_AUTO, runningbufspace, CTLFLAG_RD, &runningbufspace, 0,
132 "Amount of presently outstanding async buffer io");
133 static long bufspace;
134 #if defined(COMPAT_FREEBSD4) || defined(COMPAT_FREEBSD5) || \
135 defined(COMPAT_FREEBSD6) || defined(COMPAT_FREEBSD7)
136 SYSCTL_PROC(_vfs, OID_AUTO, bufspace, CTLTYPE_LONG|CTLFLAG_MPSAFE|CTLFLAG_RD,
137 &bufspace, 0, sysctl_bufspace, "L", "Virtual memory used for buffers");
139 SYSCTL_LONG(_vfs, OID_AUTO, bufspace, CTLFLAG_RD, &bufspace, 0,
140 "Virtual memory used for buffers");
142 static long unmapped_bufspace;
143 SYSCTL_LONG(_vfs, OID_AUTO, unmapped_bufspace, CTLFLAG_RD,
144 &unmapped_bufspace, 0,
145 "Amount of unmapped buffers, inclusive in the bufspace");
146 static long maxbufspace;
147 SYSCTL_LONG(_vfs, OID_AUTO, maxbufspace, CTLFLAG_RD, &maxbufspace, 0,
148 "Maximum allowed value of bufspace (including buf_daemon)");
149 static long bufmallocspace;
150 SYSCTL_LONG(_vfs, OID_AUTO, bufmallocspace, CTLFLAG_RD, &bufmallocspace, 0,
151 "Amount of malloced memory for buffers");
152 static long maxbufmallocspace;
153 SYSCTL_LONG(_vfs, OID_AUTO, maxmallocbufspace, CTLFLAG_RW, &maxbufmallocspace, 0,
154 "Maximum amount of malloced memory for buffers");
155 static long lobufspace;
156 SYSCTL_LONG(_vfs, OID_AUTO, lobufspace, CTLFLAG_RD, &lobufspace, 0,
157 "Minimum amount of buffers we want to have");
159 SYSCTL_LONG(_vfs, OID_AUTO, hibufspace, CTLFLAG_RD, &hibufspace, 0,
160 "Maximum allowed value of bufspace (excluding buf_daemon)");
161 static int bufreusecnt;
162 SYSCTL_INT(_vfs, OID_AUTO, bufreusecnt, CTLFLAG_RW, &bufreusecnt, 0,
163 "Number of times we have reused a buffer");
164 static int buffreekvacnt;
165 SYSCTL_INT(_vfs, OID_AUTO, buffreekvacnt, CTLFLAG_RW, &buffreekvacnt, 0,
166 "Number of times we have freed the KVA space from some buffer");
167 static int bufdefragcnt;
168 SYSCTL_INT(_vfs, OID_AUTO, bufdefragcnt, CTLFLAG_RW, &bufdefragcnt, 0,
169 "Number of times we have had to repeat buffer allocation to defragment");
170 static long lorunningspace;
171 SYSCTL_PROC(_vfs, OID_AUTO, lorunningspace, CTLTYPE_LONG | CTLFLAG_MPSAFE |
172 CTLFLAG_RW, &lorunningspace, 0, sysctl_runningspace, "L",
173 "Minimum preferred space used for in-progress I/O");
174 static long hirunningspace;
175 SYSCTL_PROC(_vfs, OID_AUTO, hirunningspace, CTLTYPE_LONG | CTLFLAG_MPSAFE |
176 CTLFLAG_RW, &hirunningspace, 0, sysctl_runningspace, "L",
177 "Maximum amount of space to use for in-progress I/O");
178 int dirtybufferflushes;
179 SYSCTL_INT(_vfs, OID_AUTO, dirtybufferflushes, CTLFLAG_RW, &dirtybufferflushes,
180 0, "Number of bdwrite to bawrite conversions to limit dirty buffers");
182 SYSCTL_INT(_vfs, OID_AUTO, bdwriteskip, CTLFLAG_RW, &bdwriteskip,
183 0, "Number of buffers supplied to bdwrite with snapshot deadlock risk");
184 int altbufferflushes;
185 SYSCTL_INT(_vfs, OID_AUTO, altbufferflushes, CTLFLAG_RW, &altbufferflushes,
186 0, "Number of fsync flushes to limit dirty buffers");
187 static int recursiveflushes;
188 SYSCTL_INT(_vfs, OID_AUTO, recursiveflushes, CTLFLAG_RW, &recursiveflushes,
189 0, "Number of flushes skipped due to being recursive");
190 static int numdirtybuffers;
191 SYSCTL_INT(_vfs, OID_AUTO, numdirtybuffers, CTLFLAG_RD, &numdirtybuffers, 0,
192 "Number of buffers that are dirty (has unwritten changes) at the moment");
193 static int lodirtybuffers;
194 SYSCTL_INT(_vfs, OID_AUTO, lodirtybuffers, CTLFLAG_RW, &lodirtybuffers, 0,
195 "How many buffers we want to have free before bufdaemon can sleep");
196 static int hidirtybuffers;
197 SYSCTL_INT(_vfs, OID_AUTO, hidirtybuffers, CTLFLAG_RW, &hidirtybuffers, 0,
198 "When the number of dirty buffers is considered severe");
200 SYSCTL_INT(_vfs, OID_AUTO, dirtybufthresh, CTLFLAG_RW, &dirtybufthresh,
201 0, "Number of bdwrite to bawrite conversions to clear dirty buffers");
202 static int numfreebuffers;
203 SYSCTL_INT(_vfs, OID_AUTO, numfreebuffers, CTLFLAG_RD, &numfreebuffers, 0,
204 "Number of free buffers");
205 static int lofreebuffers;
206 SYSCTL_INT(_vfs, OID_AUTO, lofreebuffers, CTLFLAG_RW, &lofreebuffers, 0,
208 static int hifreebuffers;
209 SYSCTL_INT(_vfs, OID_AUTO, hifreebuffers, CTLFLAG_RW, &hifreebuffers, 0,
210 "XXX Complicatedly unused");
211 static int getnewbufcalls;
212 SYSCTL_INT(_vfs, OID_AUTO, getnewbufcalls, CTLFLAG_RW, &getnewbufcalls, 0,
213 "Number of calls to getnewbuf");
214 static int getnewbufrestarts;
215 SYSCTL_INT(_vfs, OID_AUTO, getnewbufrestarts, CTLFLAG_RW, &getnewbufrestarts, 0,
216 "Number of times getnewbuf has had to restart a buffer aquisition");
217 static int mappingrestarts;
218 SYSCTL_INT(_vfs, OID_AUTO, mappingrestarts, CTLFLAG_RW, &mappingrestarts, 0,
219 "Number of times getblk has had to restart a buffer mapping for "
221 static int flushbufqtarget = 100;
222 SYSCTL_INT(_vfs, OID_AUTO, flushbufqtarget, CTLFLAG_RW, &flushbufqtarget, 0,
223 "Amount of work to do in flushbufqueues when helping bufdaemon");
224 static long notbufdflushes;
225 SYSCTL_LONG(_vfs, OID_AUTO, notbufdflushes, CTLFLAG_RD, ¬bufdflushes, 0,
226 "Number of dirty buffer flushes done by the bufdaemon helpers");
227 static long barrierwrites;
228 SYSCTL_LONG(_vfs, OID_AUTO, barrierwrites, CTLFLAG_RW, &barrierwrites, 0,
229 "Number of barrier writes");
230 SYSCTL_INT(_vfs, OID_AUTO, unmapped_buf_allowed, CTLFLAG_RD,
231 &unmapped_buf_allowed, 0,
232 "Permit the use of the unmapped i/o");
235 * Lock for the non-dirty bufqueues
237 static struct mtx_padalign bqclean;
240 * Lock for the dirty queue.
242 static struct mtx_padalign bqdirty;
245 * This lock synchronizes access to bd_request.
247 static struct mtx_padalign bdlock;
250 * This lock protects the runningbufreq and synchronizes runningbufwakeup and
251 * waitrunningbufspace().
253 static struct mtx_padalign rbreqlock;
256 * Lock that protects needsbuffer and the sleeps/wakeups surrounding it.
258 static struct rwlock_padalign nblock;
261 * Lock that protects bdirtywait.
263 static struct mtx_padalign bdirtylock;
266 * Wakeup point for bufdaemon, as well as indicator of whether it is already
267 * active. Set to 1 when the bufdaemon is already "on" the queue, 0 when it
270 static int bd_request;
273 * Request for the buf daemon to write more buffers than is indicated by
274 * lodirtybuf. This may be necessary to push out excess dependencies or
275 * defragment the address space where a simple count of the number of dirty
276 * buffers is insufficient to characterize the demand for flushing them.
278 static int bd_speedupreq;
281 * bogus page -- for I/O to/from partially complete buffers
282 * this is a temporary solution to the problem, but it is not
283 * really that bad. it would be better to split the buffer
284 * for input in the case of buffers partially already in memory,
285 * but the code is intricate enough already.
287 vm_page_t bogus_page;
290 * Synchronization (sleep/wakeup) variable for active buffer space requests.
291 * Set when wait starts, cleared prior to wakeup().
292 * Used in runningbufwakeup() and waitrunningbufspace().
294 static int runningbufreq;
297 * Synchronization (sleep/wakeup) variable for buffer requests.
298 * Can contain the VFS_BIO_NEED flags defined below; setting/clearing is done
300 * Used in numdirtywakeup(), bufspacewakeup(), bufcountadd(), bwillwrite(),
301 * getnewbuf(), and getblk().
303 static volatile int needsbuffer;
306 * Synchronization for bwillwrite() waiters.
308 static int bdirtywait;
311 * Definitions for the buffer free lists.
313 #define BUFFER_QUEUES 5 /* number of free buffer queues */
315 #define QUEUE_NONE 0 /* on no queue */
316 #define QUEUE_CLEAN 1 /* non-B_DELWRI buffers */
317 #define QUEUE_DIRTY 2 /* B_DELWRI buffers */
318 #define QUEUE_EMPTYKVA 3 /* empty buffer headers w/KVA assignment */
319 #define QUEUE_EMPTY 4 /* empty buffer headers */
320 #define QUEUE_SENTINEL 1024 /* not an queue index, but mark for sentinel */
322 /* Queues for free buffers with various properties */
323 static TAILQ_HEAD(bqueues, buf) bufqueues[BUFFER_QUEUES] = { { 0 } };
325 static int bq_len[BUFFER_QUEUES];
329 * Single global constant for BUF_WMESG, to avoid getting multiple references.
330 * buf_wmesg is referred from macros.
332 const char *buf_wmesg = BUF_WMESG;
334 #define VFS_BIO_NEED_ANY 0x01 /* any freeable buffer */
335 #define VFS_BIO_NEED_FREE 0x04 /* wait for free bufs, hi hysteresis */
336 #define VFS_BIO_NEED_BUFSPACE 0x08 /* wait for buf space, lo hysteresis */
339 sysctl_runningspace(SYSCTL_HANDLER_ARGS)
344 value = *(long *)arg1;
345 error = sysctl_handle_long(oidp, &value, 0, req);
346 if (error != 0 || req->newptr == NULL)
348 mtx_lock(&rbreqlock);
349 if (arg1 == &hirunningspace) {
350 if (value < lorunningspace)
353 hirunningspace = value;
355 KASSERT(arg1 == &lorunningspace,
356 ("%s: unknown arg1", __func__));
357 if (value > hirunningspace)
360 lorunningspace = value;
362 mtx_unlock(&rbreqlock);
366 #if defined(COMPAT_FREEBSD4) || defined(COMPAT_FREEBSD5) || \
367 defined(COMPAT_FREEBSD6) || defined(COMPAT_FREEBSD7)
369 sysctl_bufspace(SYSCTL_HANDLER_ARGS)
374 if (sizeof(int) == sizeof(long) || req->oldlen >= sizeof(long))
375 return (sysctl_handle_long(oidp, arg1, arg2, req));
376 lvalue = *(long *)arg1;
377 if (lvalue > INT_MAX)
378 /* On overflow, still write out a long to trigger ENOMEM. */
379 return (sysctl_handle_long(oidp, &lvalue, 0, req));
381 return (sysctl_handle_int(oidp, &ivalue, 0, req));
388 * Return the appropriate queue lock based on the index.
390 static inline struct mtx *
394 if (qindex == QUEUE_DIRTY)
395 return (struct mtx *)(&bqdirty);
396 return (struct mtx *)(&bqclean);
402 * Wakeup any bwillwrite() waiters.
407 mtx_lock(&bdirtylock);
412 mtx_unlock(&bdirtylock);
418 * Decrement the numdirtybuffers count by one and wakeup any
419 * threads blocked in bwillwrite().
425 if (atomic_fetchadd_int(&numdirtybuffers, -1) ==
426 (lodirtybuffers + hidirtybuffers) / 2)
433 * Increment the numdirtybuffers count by one and wakeup the buf
441 * Only do the wakeup once as we cross the boundary. The
442 * buf daemon will keep running until the condition clears.
444 if (atomic_fetchadd_int(&numdirtybuffers, 1) ==
445 (lodirtybuffers + hidirtybuffers) / 2)
452 * Called when buffer space is potentially available for recovery.
453 * getnewbuf() will block on this flag when it is unable to free
454 * sufficient buffer space. Buffer space becomes recoverable when
455 * bp's get placed back in the queues.
464 * If someone is waiting for BUF space, wake them up. Even
465 * though we haven't freed the kva space yet, the waiting
466 * process will be able to now.
472 if ((on & VFS_BIO_NEED_BUFSPACE) == 0)
475 if (atomic_cmpset_rel_int(&needsbuffer, on,
476 on & ~VFS_BIO_NEED_BUFSPACE))
480 wakeup(__DEVOLATILE(void *, &needsbuffer));
487 * Wake up processes that are waiting on asynchronous writes to fall
488 * below lorunningspace.
494 mtx_lock(&rbreqlock);
497 wakeup(&runningbufreq);
499 mtx_unlock(&rbreqlock);
505 * Decrement the outstanding write count according.
508 runningbufwakeup(struct buf *bp)
512 bspace = bp->b_runningbufspace;
515 space = atomic_fetchadd_long(&runningbufspace, -bspace);
516 KASSERT(space >= bspace, ("runningbufspace underflow %ld %ld",
518 bp->b_runningbufspace = 0;
520 * Only acquire the lock and wakeup on the transition from exceeding
521 * the threshold to falling below it.
523 if (space < lorunningspace)
525 if (space - bspace > lorunningspace)
533 * Called when a buffer has been added to one of the free queues to
534 * account for the buffer and to wakeup anyone waiting for free buffers.
535 * This typically occurs when large amounts of metadata are being handled
536 * by the buffer cache ( else buffer space runs out first, usually ).
539 bufcountadd(struct buf *bp)
541 int mask, need_wakeup, old, on;
543 KASSERT((bp->b_flags & B_INFREECNT) == 0,
544 ("buf %p already counted as free", bp));
545 bp->b_flags |= B_INFREECNT;
546 old = atomic_fetchadd_int(&numfreebuffers, 1);
547 KASSERT(old >= 0 && old < nbuf,
548 ("numfreebuffers climbed to %d", old + 1));
549 mask = VFS_BIO_NEED_ANY;
550 if (numfreebuffers >= hifreebuffers)
551 mask |= VFS_BIO_NEED_FREE;
559 if (atomic_cmpset_rel_int(&needsbuffer, on, on & ~mask))
563 wakeup(__DEVOLATILE(void *, &needsbuffer));
570 * Decrement the numfreebuffers count as needed.
573 bufcountsub(struct buf *bp)
578 * Fixup numfreebuffers count. If the buffer is invalid or not
579 * delayed-write, the buffer was free and we must decrement
582 if ((bp->b_flags & B_INVAL) || (bp->b_flags & B_DELWRI) == 0) {
583 KASSERT((bp->b_flags & B_INFREECNT) != 0,
584 ("buf %p not counted in numfreebuffers", bp));
585 bp->b_flags &= ~B_INFREECNT;
586 old = atomic_fetchadd_int(&numfreebuffers, -1);
587 KASSERT(old > 0, ("numfreebuffers dropped to %d", old - 1));
592 * waitrunningbufspace()
594 * runningbufspace is a measure of the amount of I/O currently
595 * running. This routine is used in async-write situations to
596 * prevent creating huge backups of pending writes to a device.
597 * Only asynchronous writes are governed by this function.
599 * This does NOT turn an async write into a sync write. It waits
600 * for earlier writes to complete and generally returns before the
601 * caller's write has reached the device.
604 waitrunningbufspace(void)
607 mtx_lock(&rbreqlock);
608 while (runningbufspace > hirunningspace) {
610 msleep(&runningbufreq, &rbreqlock, PVM, "wdrain", 0);
612 mtx_unlock(&rbreqlock);
617 * vfs_buf_test_cache:
619 * Called when a buffer is extended. This function clears the B_CACHE
620 * bit if the newly extended portion of the buffer does not contain
625 vfs_buf_test_cache(struct buf *bp,
626 vm_ooffset_t foff, vm_offset_t off, vm_offset_t size,
630 VM_OBJECT_ASSERT_LOCKED(m->object);
631 if (bp->b_flags & B_CACHE) {
632 int base = (foff + off) & PAGE_MASK;
633 if (vm_page_is_valid(m, base, size) == 0)
634 bp->b_flags &= ~B_CACHE;
638 /* Wake up the buffer daemon if necessary */
644 if (bd_request == 0) {
652 * bd_speedup - speedup the buffer cache flushing code
661 if (bd_speedupreq == 0 || bd_request == 0)
671 #define NSWBUF_MIN 16
675 #define TRANSIENT_DENOM 5
677 #define TRANSIENT_DENOM 10
681 * Calculating buffer cache scaling values and reserve space for buffer
682 * headers. This is called during low level kernel initialization and
683 * may be called more then once. We CANNOT write to the memory area
684 * being reserved at this time.
687 kern_vfs_bio_buffer_alloc(caddr_t v, long physmem_est)
690 long maxbuf, maxbuf_sz, buf_sz, biotmap_sz;
693 * physmem_est is in pages. Convert it to kilobytes (assumes
694 * PAGE_SIZE is >= 1K)
696 physmem_est = physmem_est * (PAGE_SIZE / 1024);
699 * The nominal buffer size (and minimum KVA allocation) is BKVASIZE.
700 * For the first 64MB of ram nominally allocate sufficient buffers to
701 * cover 1/4 of our ram. Beyond the first 64MB allocate additional
702 * buffers to cover 1/10 of our ram over 64MB. When auto-sizing
703 * the buffer cache we limit the eventual kva reservation to
706 * factor represents the 1/4 x ram conversion.
709 int factor = 4 * BKVASIZE / 1024;
712 if (physmem_est > 4096)
713 nbuf += min((physmem_est - 4096) / factor,
715 if (physmem_est > 65536)
716 nbuf += min((physmem_est - 65536) * 2 / (factor * 5),
717 32 * 1024 * 1024 / (factor * 5));
719 if (maxbcache && nbuf > maxbcache / BKVASIZE)
720 nbuf = maxbcache / BKVASIZE;
725 /* XXX Avoid unsigned long overflows later on with maxbufspace. */
726 maxbuf = (LONG_MAX / 3) / BKVASIZE;
729 printf("Warning: nbufs lowered from %d to %ld\n", nbuf,
735 * Ideal allocation size for the transient bio submap is 10%
736 * of the maximal space buffer map. This roughly corresponds
737 * to the amount of the buffer mapped for typical UFS load.
739 * Clip the buffer map to reserve space for the transient
740 * BIOs, if its extent is bigger than 90% (80% on i386) of the
741 * maximum buffer map extent on the platform.
743 * The fall-back to the maxbuf in case of maxbcache unset,
744 * allows to not trim the buffer KVA for the architectures
745 * with ample KVA space.
747 if (bio_transient_maxcnt == 0 && unmapped_buf_allowed) {
748 maxbuf_sz = maxbcache != 0 ? maxbcache : maxbuf * BKVASIZE;
749 buf_sz = (long)nbuf * BKVASIZE;
750 if (buf_sz < maxbuf_sz / TRANSIENT_DENOM *
751 (TRANSIENT_DENOM - 1)) {
753 * There is more KVA than memory. Do not
754 * adjust buffer map size, and assign the rest
755 * of maxbuf to transient map.
757 biotmap_sz = maxbuf_sz - buf_sz;
760 * Buffer map spans all KVA we could afford on
761 * this platform. Give 10% (20% on i386) of
762 * the buffer map to the transient bio map.
764 biotmap_sz = buf_sz / TRANSIENT_DENOM;
765 buf_sz -= biotmap_sz;
767 if (biotmap_sz / INT_MAX > MAXPHYS)
768 bio_transient_maxcnt = INT_MAX;
770 bio_transient_maxcnt = biotmap_sz / MAXPHYS;
772 * Artifically limit to 1024 simultaneous in-flight I/Os
773 * using the transient mapping.
775 if (bio_transient_maxcnt > 1024)
776 bio_transient_maxcnt = 1024;
778 nbuf = buf_sz / BKVASIZE;
782 * swbufs are used as temporary holders for I/O, such as paging I/O.
783 * We have no less then 16 and no more then 256.
785 nswbuf = min(nbuf / 4, 256);
786 TUNABLE_INT_FETCH("kern.nswbuf", &nswbuf);
787 if (nswbuf < NSWBUF_MIN)
791 * Reserve space for the buffer cache buffers
794 v = (caddr_t)(swbuf + nswbuf);
796 v = (caddr_t)(buf + nbuf);
801 /* Initialize the buffer subsystem. Called before use of any buffers. */
808 mtx_init(&bqclean, "bufq clean lock", NULL, MTX_DEF);
809 mtx_init(&bqdirty, "bufq dirty lock", NULL, MTX_DEF);
810 mtx_init(&rbreqlock, "runningbufspace lock", NULL, MTX_DEF);
811 rw_init(&nblock, "needsbuffer lock");
812 mtx_init(&bdlock, "buffer daemon lock", NULL, MTX_DEF);
813 mtx_init(&bdirtylock, "dirty buf lock", NULL, MTX_DEF);
815 /* next, make a null set of free lists */
816 for (i = 0; i < BUFFER_QUEUES; i++)
817 TAILQ_INIT(&bufqueues[i]);
819 /* finally, initialize each buffer header and stick on empty q */
820 for (i = 0; i < nbuf; i++) {
822 bzero(bp, sizeof *bp);
823 bp->b_flags = B_INVAL | B_INFREECNT;
824 bp->b_rcred = NOCRED;
825 bp->b_wcred = NOCRED;
826 bp->b_qindex = QUEUE_EMPTY;
828 LIST_INIT(&bp->b_dep);
830 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_EMPTY], bp, b_freelist);
832 bq_len[QUEUE_EMPTY]++;
837 * maxbufspace is the absolute maximum amount of buffer space we are
838 * allowed to reserve in KVM and in real terms. The absolute maximum
839 * is nominally used by buf_daemon. hibufspace is the nominal maximum
840 * used by most other processes. The differential is required to
841 * ensure that buf_daemon is able to run when other processes might
842 * be blocked waiting for buffer space.
844 * maxbufspace is based on BKVASIZE. Allocating buffers larger then
845 * this may result in KVM fragmentation which is not handled optimally
848 maxbufspace = (long)nbuf * BKVASIZE;
849 hibufspace = lmax(3 * maxbufspace / 4, maxbufspace - MAXBSIZE * 10);
850 lobufspace = hibufspace - MAXBSIZE;
853 * Note: The 16 MiB upper limit for hirunningspace was chosen
854 * arbitrarily and may need further tuning. It corresponds to
855 * 128 outstanding write IO requests (if IO size is 128 KiB),
856 * which fits with many RAID controllers' tagged queuing limits.
857 * The lower 1 MiB limit is the historical upper limit for
860 hirunningspace = lmax(lmin(roundup(hibufspace / 64, MAXBSIZE),
861 16 * 1024 * 1024), 1024 * 1024);
862 lorunningspace = roundup((hirunningspace * 2) / 3, MAXBSIZE);
865 * Limit the amount of malloc memory since it is wired permanently into
866 * the kernel space. Even though this is accounted for in the buffer
867 * allocation, we don't want the malloced region to grow uncontrolled.
868 * The malloc scheme improves memory utilization significantly on average
869 * (small) directories.
871 maxbufmallocspace = hibufspace / 20;
874 * Reduce the chance of a deadlock occuring by limiting the number
875 * of delayed-write dirty buffers we allow to stack up.
877 hidirtybuffers = nbuf / 4 + 20;
878 dirtybufthresh = hidirtybuffers * 9 / 10;
881 * To support extreme low-memory systems, make sure hidirtybuffers cannot
882 * eat up all available buffer space. This occurs when our minimum cannot
883 * be met. We try to size hidirtybuffers to 3/4 our buffer space assuming
884 * BKVASIZE'd buffers.
886 while ((long)hidirtybuffers * BKVASIZE > 3 * hibufspace / 4) {
887 hidirtybuffers >>= 1;
889 lodirtybuffers = hidirtybuffers / 2;
892 * Try to keep the number of free buffers in the specified range,
893 * and give special processes (e.g. like buf_daemon) access to an
896 lofreebuffers = nbuf / 18 + 5;
897 hifreebuffers = 2 * lofreebuffers;
898 numfreebuffers = nbuf;
900 bogus_page = vm_page_alloc(NULL, 0, VM_ALLOC_NOOBJ |
901 VM_ALLOC_NORMAL | VM_ALLOC_WIRED);
902 unmapped_buf = (caddr_t)kva_alloc(MAXPHYS);
907 vfs_buf_check_mapped(struct buf *bp)
910 KASSERT((bp->b_flags & B_UNMAPPED) == 0,
911 ("mapped buf %p %x", bp, bp->b_flags));
912 KASSERT(bp->b_kvabase != unmapped_buf,
913 ("mapped buf: b_kvabase was not updated %p", bp));
914 KASSERT(bp->b_data != unmapped_buf,
915 ("mapped buf: b_data was not updated %p", bp));
919 vfs_buf_check_unmapped(struct buf *bp)
922 KASSERT((bp->b_flags & B_UNMAPPED) == B_UNMAPPED,
923 ("unmapped buf %p %x", bp, bp->b_flags));
924 KASSERT(bp->b_kvabase == unmapped_buf,
925 ("unmapped buf: corrupted b_kvabase %p", bp));
926 KASSERT(bp->b_data == unmapped_buf,
927 ("unmapped buf: corrupted b_data %p", bp));
930 #define BUF_CHECK_MAPPED(bp) vfs_buf_check_mapped(bp)
931 #define BUF_CHECK_UNMAPPED(bp) vfs_buf_check_unmapped(bp)
933 #define BUF_CHECK_MAPPED(bp) do {} while (0)
934 #define BUF_CHECK_UNMAPPED(bp) do {} while (0)
938 bpmap_qenter(struct buf *bp)
941 BUF_CHECK_MAPPED(bp);
944 * bp->b_data is relative to bp->b_offset, but
945 * bp->b_offset may be offset into the first page.
947 bp->b_data = (caddr_t)trunc_page((vm_offset_t)bp->b_data);
948 pmap_qenter((vm_offset_t)bp->b_data, bp->b_pages, bp->b_npages);
949 bp->b_data = (caddr_t)((vm_offset_t)bp->b_data |
950 (vm_offset_t)(bp->b_offset & PAGE_MASK));
954 * bfreekva() - free the kva allocation for a buffer.
956 * Since this call frees up buffer space, we call bufspacewakeup().
959 bfreekva(struct buf *bp)
962 if (bp->b_kvasize == 0)
965 atomic_add_int(&buffreekvacnt, 1);
966 atomic_subtract_long(&bufspace, bp->b_kvasize);
967 if ((bp->b_flags & B_UNMAPPED) == 0) {
968 BUF_CHECK_MAPPED(bp);
969 vmem_free(buffer_arena, (vm_offset_t)bp->b_kvabase,
972 BUF_CHECK_UNMAPPED(bp);
973 if ((bp->b_flags & B_KVAALLOC) != 0) {
974 vmem_free(buffer_arena, (vm_offset_t)bp->b_kvaalloc,
977 atomic_subtract_long(&unmapped_bufspace, bp->b_kvasize);
978 bp->b_flags &= ~(B_UNMAPPED | B_KVAALLOC);
987 * Insert the buffer into the appropriate free list.
990 binsfree(struct buf *bp, int qindex)
992 struct mtx *olock, *nlock;
994 BUF_ASSERT_XLOCKED(bp);
996 olock = bqlock(bp->b_qindex);
997 nlock = bqlock(qindex);
999 /* Handle delayed bremfree() processing. */
1000 if (bp->b_flags & B_REMFREE)
1003 if (bp->b_qindex != QUEUE_NONE)
1004 panic("binsfree: free buffer onto another queue???");
1006 bp->b_qindex = qindex;
1007 if (olock != nlock) {
1011 if (bp->b_flags & B_AGE)
1012 TAILQ_INSERT_HEAD(&bufqueues[bp->b_qindex], bp, b_freelist);
1014 TAILQ_INSERT_TAIL(&bufqueues[bp->b_qindex], bp, b_freelist);
1016 bq_len[bp->b_qindex]++;
1021 * Something we can maybe free or reuse.
1023 if (bp->b_bufsize && !(bp->b_flags & B_DELWRI))
1026 if ((bp->b_flags & B_INVAL) || !(bp->b_flags & B_DELWRI))
1033 * Mark the buffer for removal from the appropriate free list.
1037 bremfree(struct buf *bp)
1040 CTR3(KTR_BUF, "bremfree(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
1041 KASSERT((bp->b_flags & B_REMFREE) == 0,
1042 ("bremfree: buffer %p already marked for delayed removal.", bp));
1043 KASSERT(bp->b_qindex != QUEUE_NONE,
1044 ("bremfree: buffer %p not on a queue.", bp));
1045 BUF_ASSERT_XLOCKED(bp);
1047 bp->b_flags |= B_REMFREE;
1054 * Force an immediate removal from a free list. Used only in nfs when
1055 * it abuses the b_freelist pointer.
1058 bremfreef(struct buf *bp)
1062 qlock = bqlock(bp->b_qindex);
1071 * Removes a buffer from the free list, must be called with the
1072 * correct qlock held.
1075 bremfreel(struct buf *bp)
1078 CTR3(KTR_BUF, "bremfreel(%p) vp %p flags %X",
1079 bp, bp->b_vp, bp->b_flags);
1080 KASSERT(bp->b_qindex != QUEUE_NONE,
1081 ("bremfreel: buffer %p not on a queue.", bp));
1082 BUF_ASSERT_XLOCKED(bp);
1083 mtx_assert(bqlock(bp->b_qindex), MA_OWNED);
1085 TAILQ_REMOVE(&bufqueues[bp->b_qindex], bp, b_freelist);
1087 KASSERT(bq_len[bp->b_qindex] >= 1, ("queue %d underflow",
1089 bq_len[bp->b_qindex]--;
1091 bp->b_qindex = QUEUE_NONE;
1093 * If this was a delayed bremfree() we only need to remove the buffer
1094 * from the queue and return the stats are already done.
1096 if (bp->b_flags & B_REMFREE) {
1097 bp->b_flags &= ~B_REMFREE;
1104 * Attempt to initiate asynchronous I/O on read-ahead blocks. We must
1105 * clear BIO_ERROR and B_INVAL prior to initiating I/O . If B_CACHE is set,
1106 * the buffer is valid and we do not have to do anything.
1109 breada(struct vnode * vp, daddr_t * rablkno, int * rabsize,
1110 int cnt, struct ucred * cred)
1115 for (i = 0; i < cnt; i++, rablkno++, rabsize++) {
1116 if (inmem(vp, *rablkno))
1118 rabp = getblk(vp, *rablkno, *rabsize, 0, 0, 0);
1120 if ((rabp->b_flags & B_CACHE) == 0) {
1121 if (!TD_IS_IDLETHREAD(curthread))
1122 curthread->td_ru.ru_inblock++;
1123 rabp->b_flags |= B_ASYNC;
1124 rabp->b_flags &= ~B_INVAL;
1125 rabp->b_ioflags &= ~BIO_ERROR;
1126 rabp->b_iocmd = BIO_READ;
1127 if (rabp->b_rcred == NOCRED && cred != NOCRED)
1128 rabp->b_rcred = crhold(cred);
1129 vfs_busy_pages(rabp, 0);
1131 rabp->b_iooffset = dbtob(rabp->b_blkno);
1140 * Entry point for bread() and breadn() via #defines in sys/buf.h.
1142 * Get a buffer with the specified data. Look in the cache first. We
1143 * must clear BIO_ERROR and B_INVAL prior to initiating I/O. If B_CACHE
1144 * is set, the buffer is valid and we do not have to do anything, see
1145 * getblk(). Also starts asynchronous I/O on read-ahead blocks.
1148 breadn_flags(struct vnode *vp, daddr_t blkno, int size, daddr_t *rablkno,
1149 int *rabsize, int cnt, struct ucred *cred, int flags, struct buf **bpp)
1152 int rv = 0, readwait = 0;
1154 CTR3(KTR_BUF, "breadn(%p, %jd, %d)", vp, blkno, size);
1156 * Can only return NULL if GB_LOCK_NOWAIT flag is specified.
1158 *bpp = bp = getblk(vp, blkno, size, 0, 0, flags);
1162 /* if not found in cache, do some I/O */
1163 if ((bp->b_flags & B_CACHE) == 0) {
1164 if (!TD_IS_IDLETHREAD(curthread))
1165 curthread->td_ru.ru_inblock++;
1166 bp->b_iocmd = BIO_READ;
1167 bp->b_flags &= ~B_INVAL;
1168 bp->b_ioflags &= ~BIO_ERROR;
1169 if (bp->b_rcred == NOCRED && cred != NOCRED)
1170 bp->b_rcred = crhold(cred);
1171 vfs_busy_pages(bp, 0);
1172 bp->b_iooffset = dbtob(bp->b_blkno);
1177 breada(vp, rablkno, rabsize, cnt, cred);
1186 * Write, release buffer on completion. (Done by iodone
1187 * if async). Do not bother writing anything if the buffer
1190 * Note that we set B_CACHE here, indicating that buffer is
1191 * fully valid and thus cacheable. This is true even of NFS
1192 * now so we set it generally. This could be set either here
1193 * or in biodone() since the I/O is synchronous. We put it
1197 bufwrite(struct buf *bp)
1204 CTR3(KTR_BUF, "bufwrite(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
1205 if (bp->b_flags & B_INVAL) {
1210 if (bp->b_flags & B_BARRIER)
1213 oldflags = bp->b_flags;
1215 BUF_ASSERT_HELD(bp);
1217 if (bp->b_pin_count > 0)
1220 KASSERT(!(bp->b_vflags & BV_BKGRDINPROG),
1221 ("FFS background buffer should not get here %p", bp));
1225 vp_md = vp->v_vflag & VV_MD;
1230 * Mark the buffer clean. Increment the bufobj write count
1231 * before bundirty() call, to prevent other thread from seeing
1232 * empty dirty list and zero counter for writes in progress,
1233 * falsely indicating that the bufobj is clean.
1235 bufobj_wref(bp->b_bufobj);
1238 bp->b_flags &= ~B_DONE;
1239 bp->b_ioflags &= ~BIO_ERROR;
1240 bp->b_flags |= B_CACHE;
1241 bp->b_iocmd = BIO_WRITE;
1243 vfs_busy_pages(bp, 1);
1246 * Normal bwrites pipeline writes
1248 bp->b_runningbufspace = bp->b_bufsize;
1249 space = atomic_fetchadd_long(&runningbufspace, bp->b_runningbufspace);
1251 if (!TD_IS_IDLETHREAD(curthread))
1252 curthread->td_ru.ru_oublock++;
1253 if (oldflags & B_ASYNC)
1255 bp->b_iooffset = dbtob(bp->b_blkno);
1258 if ((oldflags & B_ASYNC) == 0) {
1259 int rtval = bufwait(bp);
1262 } else if (space > hirunningspace) {
1264 * don't allow the async write to saturate the I/O
1265 * system. We will not deadlock here because
1266 * we are blocking waiting for I/O that is already in-progress
1267 * to complete. We do not block here if it is the update
1268 * or syncer daemon trying to clean up as that can lead
1271 if ((curthread->td_pflags & TDP_NORUNNINGBUF) == 0 && !vp_md)
1272 waitrunningbufspace();
1279 bufbdflush(struct bufobj *bo, struct buf *bp)
1283 if (bo->bo_dirty.bv_cnt > dirtybufthresh + 10) {
1284 (void) VOP_FSYNC(bp->b_vp, MNT_NOWAIT, curthread);
1286 } else if (bo->bo_dirty.bv_cnt > dirtybufthresh) {
1289 * Try to find a buffer to flush.
1291 TAILQ_FOREACH(nbp, &bo->bo_dirty.bv_hd, b_bobufs) {
1292 if ((nbp->b_vflags & BV_BKGRDINPROG) ||
1294 LK_EXCLUSIVE | LK_NOWAIT, NULL))
1297 panic("bdwrite: found ourselves");
1299 /* Don't countdeps with the bo lock held. */
1300 if (buf_countdeps(nbp, 0)) {
1305 if (nbp->b_flags & B_CLUSTEROK) {
1306 vfs_bio_awrite(nbp);
1311 dirtybufferflushes++;
1320 * Delayed write. (Buffer is marked dirty). Do not bother writing
1321 * anything if the buffer is marked invalid.
1323 * Note that since the buffer must be completely valid, we can safely
1324 * set B_CACHE. In fact, we have to set B_CACHE here rather then in
1325 * biodone() in order to prevent getblk from writing the buffer
1326 * out synchronously.
1329 bdwrite(struct buf *bp)
1331 struct thread *td = curthread;
1335 CTR3(KTR_BUF, "bdwrite(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
1336 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp));
1337 KASSERT((bp->b_flags & B_BARRIER) == 0,
1338 ("Barrier request in delayed write %p", bp));
1339 BUF_ASSERT_HELD(bp);
1341 if (bp->b_flags & B_INVAL) {
1347 * If we have too many dirty buffers, don't create any more.
1348 * If we are wildly over our limit, then force a complete
1349 * cleanup. Otherwise, just keep the situation from getting
1350 * out of control. Note that we have to avoid a recursive
1351 * disaster and not try to clean up after our own cleanup!
1355 if ((td->td_pflags & (TDP_COWINPROGRESS|TDP_INBDFLUSH)) == 0) {
1356 td->td_pflags |= TDP_INBDFLUSH;
1358 td->td_pflags &= ~TDP_INBDFLUSH;
1364 * Set B_CACHE, indicating that the buffer is fully valid. This is
1365 * true even of NFS now.
1367 bp->b_flags |= B_CACHE;
1370 * This bmap keeps the system from needing to do the bmap later,
1371 * perhaps when the system is attempting to do a sync. Since it
1372 * is likely that the indirect block -- or whatever other datastructure
1373 * that the filesystem needs is still in memory now, it is a good
1374 * thing to do this. Note also, that if the pageout daemon is
1375 * requesting a sync -- there might not be enough memory to do
1376 * the bmap then... So, this is important to do.
1378 if (vp->v_type != VCHR && bp->b_lblkno == bp->b_blkno) {
1379 VOP_BMAP(vp, bp->b_lblkno, NULL, &bp->b_blkno, NULL, NULL);
1383 * Set the *dirty* buffer range based upon the VM system dirty
1386 * Mark the buffer pages as clean. We need to do this here to
1387 * satisfy the vnode_pager and the pageout daemon, so that it
1388 * thinks that the pages have been "cleaned". Note that since
1389 * the pages are in a delayed write buffer -- the VFS layer
1390 * "will" see that the pages get written out on the next sync,
1391 * or perhaps the cluster will be completed.
1393 vfs_clean_pages_dirty_buf(bp);
1397 * note: we cannot initiate I/O from a bdwrite even if we wanted to,
1398 * due to the softdep code.
1405 * Turn buffer into delayed write request. We must clear BIO_READ and
1406 * B_RELBUF, and we must set B_DELWRI. We reassign the buffer to
1407 * itself to properly update it in the dirty/clean lists. We mark it
1408 * B_DONE to ensure that any asynchronization of the buffer properly
1409 * clears B_DONE ( else a panic will occur later ).
1411 * bdirty() is kinda like bdwrite() - we have to clear B_INVAL which
1412 * might have been set pre-getblk(). Unlike bwrite/bdwrite, bdirty()
1413 * should only be called if the buffer is known-good.
1415 * Since the buffer is not on a queue, we do not update the numfreebuffers
1418 * The buffer must be on QUEUE_NONE.
1421 bdirty(struct buf *bp)
1424 CTR3(KTR_BUF, "bdirty(%p) vp %p flags %X",
1425 bp, bp->b_vp, bp->b_flags);
1426 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp));
1427 KASSERT(bp->b_flags & B_REMFREE || bp->b_qindex == QUEUE_NONE,
1428 ("bdirty: buffer %p still on queue %d", bp, bp->b_qindex));
1429 BUF_ASSERT_HELD(bp);
1430 bp->b_flags &= ~(B_RELBUF);
1431 bp->b_iocmd = BIO_WRITE;
1433 if ((bp->b_flags & B_DELWRI) == 0) {
1434 bp->b_flags |= /* XXX B_DONE | */ B_DELWRI;
1443 * Clear B_DELWRI for buffer.
1445 * Since the buffer is not on a queue, we do not update the numfreebuffers
1448 * The buffer must be on QUEUE_NONE.
1452 bundirty(struct buf *bp)
1455 CTR3(KTR_BUF, "bundirty(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
1456 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp));
1457 KASSERT(bp->b_flags & B_REMFREE || bp->b_qindex == QUEUE_NONE,
1458 ("bundirty: buffer %p still on queue %d", bp, bp->b_qindex));
1459 BUF_ASSERT_HELD(bp);
1461 if (bp->b_flags & B_DELWRI) {
1462 bp->b_flags &= ~B_DELWRI;
1467 * Since it is now being written, we can clear its deferred write flag.
1469 bp->b_flags &= ~B_DEFERRED;
1475 * Asynchronous write. Start output on a buffer, but do not wait for
1476 * it to complete. The buffer is released when the output completes.
1478 * bwrite() ( or the VOP routine anyway ) is responsible for handling
1479 * B_INVAL buffers. Not us.
1482 bawrite(struct buf *bp)
1485 bp->b_flags |= B_ASYNC;
1492 * Asynchronous barrier write. Start output on a buffer, but do not
1493 * wait for it to complete. Place a write barrier after this write so
1494 * that this buffer and all buffers written before it are committed to
1495 * the disk before any buffers written after this write are committed
1496 * to the disk. The buffer is released when the output completes.
1499 babarrierwrite(struct buf *bp)
1502 bp->b_flags |= B_ASYNC | B_BARRIER;
1509 * Synchronous barrier write. Start output on a buffer and wait for
1510 * it to complete. Place a write barrier after this write so that
1511 * this buffer and all buffers written before it are committed to
1512 * the disk before any buffers written after this write are committed
1513 * to the disk. The buffer is released when the output completes.
1516 bbarrierwrite(struct buf *bp)
1519 bp->b_flags |= B_BARRIER;
1520 return (bwrite(bp));
1526 * Called prior to the locking of any vnodes when we are expecting to
1527 * write. We do not want to starve the buffer cache with too many
1528 * dirty buffers so we block here. By blocking prior to the locking
1529 * of any vnodes we attempt to avoid the situation where a locked vnode
1530 * prevents the various system daemons from flushing related buffers.
1536 if (numdirtybuffers >= hidirtybuffers) {
1537 mtx_lock(&bdirtylock);
1538 while (numdirtybuffers >= hidirtybuffers) {
1540 msleep(&bdirtywait, &bdirtylock, (PRIBIO + 4),
1543 mtx_unlock(&bdirtylock);
1548 * Return true if we have too many dirty buffers.
1551 buf_dirty_count_severe(void)
1554 return(numdirtybuffers >= hidirtybuffers);
1557 static __noinline int
1558 buf_vm_page_count_severe(void)
1561 KFAIL_POINT_CODE(DEBUG_FP, buf_pressure, return 1);
1563 return vm_page_count_severe();
1569 * Release a busy buffer and, if requested, free its resources. The
1570 * buffer will be stashed in the appropriate bufqueue[] allowing it
1571 * to be accessed later as a cache entity or reused for other purposes.
1574 brelse(struct buf *bp)
1578 CTR3(KTR_BUF, "brelse(%p) vp %p flags %X",
1579 bp, bp->b_vp, bp->b_flags);
1580 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)),
1581 ("brelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp));
1583 if (BUF_LOCKRECURSED(bp)) {
1585 * Do not process, in particular, do not handle the
1586 * B_INVAL/B_RELBUF and do not release to free list.
1592 if (bp->b_flags & B_MANAGED) {
1597 if (bp->b_iocmd == BIO_WRITE && (bp->b_ioflags & BIO_ERROR) &&
1598 bp->b_error == EIO && !(bp->b_flags & B_INVAL)) {
1600 * Failed write, redirty. Must clear BIO_ERROR to prevent
1601 * pages from being scrapped. If the error is anything
1602 * other than an I/O error (EIO), assume that retrying
1605 bp->b_ioflags &= ~BIO_ERROR;
1607 } else if ((bp->b_flags & (B_NOCACHE | B_INVAL)) ||
1608 (bp->b_ioflags & BIO_ERROR) || (bp->b_bufsize <= 0)) {
1610 * Either a failed I/O or we were asked to free or not
1613 bp->b_flags |= B_INVAL;
1614 if (!LIST_EMPTY(&bp->b_dep))
1616 if (bp->b_flags & B_DELWRI)
1618 bp->b_flags &= ~(B_DELWRI | B_CACHE);
1619 if ((bp->b_flags & B_VMIO) == 0) {
1628 * We must clear B_RELBUF if B_DELWRI is set. If vfs_vmio_release()
1629 * is called with B_DELWRI set, the underlying pages may wind up
1630 * getting freed causing a previous write (bdwrite()) to get 'lost'
1631 * because pages associated with a B_DELWRI bp are marked clean.
1633 * We still allow the B_INVAL case to call vfs_vmio_release(), even
1634 * if B_DELWRI is set.
1636 * If B_DELWRI is not set we may have to set B_RELBUF if we are low
1637 * on pages to return pages to the VM page queues.
1639 if (bp->b_flags & B_DELWRI)
1640 bp->b_flags &= ~B_RELBUF;
1641 else if (buf_vm_page_count_severe()) {
1643 * BKGRDINPROG can only be set with the buf and bufobj
1644 * locks both held. We tolerate a race to clear it here.
1646 if (!(bp->b_vflags & BV_BKGRDINPROG))
1647 bp->b_flags |= B_RELBUF;
1651 * VMIO buffer rundown. It is not very necessary to keep a VMIO buffer
1652 * constituted, not even NFS buffers now. Two flags effect this. If
1653 * B_INVAL, the struct buf is invalidated but the VM object is kept
1654 * around ( i.e. so it is trivial to reconstitute the buffer later ).
1656 * If BIO_ERROR or B_NOCACHE is set, pages in the VM object will be
1657 * invalidated. BIO_ERROR cannot be set for a failed write unless the
1658 * buffer is also B_INVAL because it hits the re-dirtying code above.
1660 * Normally we can do this whether a buffer is B_DELWRI or not. If
1661 * the buffer is an NFS buffer, it is tracking piecemeal writes or
1662 * the commit state and we cannot afford to lose the buffer. If the
1663 * buffer has a background write in progress, we need to keep it
1664 * around to prevent it from being reconstituted and starting a second
1667 if ((bp->b_flags & B_VMIO)
1668 && !(bp->b_vp->v_mount != NULL &&
1669 (bp->b_vp->v_mount->mnt_vfc->vfc_flags & VFCF_NETWORK) != 0 &&
1670 !vn_isdisk(bp->b_vp, NULL) &&
1671 (bp->b_flags & B_DELWRI))
1680 obj = bp->b_bufobj->bo_object;
1683 * Get the base offset and length of the buffer. Note that
1684 * in the VMIO case if the buffer block size is not
1685 * page-aligned then b_data pointer may not be page-aligned.
1686 * But our b_pages[] array *IS* page aligned.
1688 * block sizes less then DEV_BSIZE (usually 512) are not
1689 * supported due to the page granularity bits (m->valid,
1690 * m->dirty, etc...).
1692 * See man buf(9) for more information
1694 resid = bp->b_bufsize;
1695 foff = bp->b_offset;
1696 for (i = 0; i < bp->b_npages; i++) {
1702 * If we hit a bogus page, fixup *all* the bogus pages
1705 if (m == bogus_page) {
1706 poff = OFF_TO_IDX(bp->b_offset);
1709 VM_OBJECT_RLOCK(obj);
1710 for (j = i; j < bp->b_npages; j++) {
1712 mtmp = bp->b_pages[j];
1713 if (mtmp == bogus_page) {
1714 mtmp = vm_page_lookup(obj, poff + j);
1716 panic("brelse: page missing\n");
1718 bp->b_pages[j] = mtmp;
1721 VM_OBJECT_RUNLOCK(obj);
1723 if ((bp->b_flags & (B_INVAL | B_UNMAPPED)) == 0) {
1724 BUF_CHECK_MAPPED(bp);
1726 trunc_page((vm_offset_t)bp->b_data),
1727 bp->b_pages, bp->b_npages);
1731 if ((bp->b_flags & B_NOCACHE) ||
1732 (bp->b_ioflags & BIO_ERROR &&
1733 bp->b_iocmd == BIO_READ)) {
1734 int poffset = foff & PAGE_MASK;
1735 int presid = resid > (PAGE_SIZE - poffset) ?
1736 (PAGE_SIZE - poffset) : resid;
1738 KASSERT(presid >= 0, ("brelse: extra page"));
1739 VM_OBJECT_WLOCK(obj);
1740 while (vm_page_xbusied(m)) {
1742 VM_OBJECT_WUNLOCK(obj);
1743 vm_page_busy_sleep(m, "mbncsh");
1744 VM_OBJECT_WLOCK(obj);
1746 if (pmap_page_wired_mappings(m) == 0)
1747 vm_page_set_invalid(m, poffset, presid);
1748 VM_OBJECT_WUNLOCK(obj);
1750 printf("avoided corruption bug in bogus_page/brelse code\n");
1752 resid -= PAGE_SIZE - (foff & PAGE_MASK);
1753 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK;
1755 if (bp->b_flags & (B_INVAL | B_RELBUF))
1756 vfs_vmio_release(bp);
1758 } else if (bp->b_flags & B_VMIO) {
1760 if (bp->b_flags & (B_INVAL | B_RELBUF)) {
1761 vfs_vmio_release(bp);
1764 } else if ((bp->b_flags & (B_INVAL | B_RELBUF)) != 0) {
1765 if (bp->b_bufsize != 0)
1767 if (bp->b_vp != NULL)
1772 * If the buffer has junk contents signal it and eventually
1773 * clean up B_DELWRI and diassociate the vnode so that gbincore()
1776 if (bp->b_bufsize == 0 || (bp->b_ioflags & BIO_ERROR) != 0 ||
1777 (bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF)) != 0)
1778 bp->b_flags |= B_INVAL;
1779 if (bp->b_flags & B_INVAL) {
1780 if (bp->b_flags & B_DELWRI)
1786 /* buffers with no memory */
1787 if (bp->b_bufsize == 0) {
1788 bp->b_xflags &= ~(BX_BKGRDWRITE | BX_ALTDATA);
1789 if (bp->b_vflags & BV_BKGRDINPROG)
1790 panic("losing buffer 1");
1792 qindex = QUEUE_EMPTYKVA;
1794 qindex = QUEUE_EMPTY;
1795 bp->b_flags |= B_AGE;
1796 /* buffers with junk contents */
1797 } else if (bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF) ||
1798 (bp->b_ioflags & BIO_ERROR)) {
1799 bp->b_xflags &= ~(BX_BKGRDWRITE | BX_ALTDATA);
1800 if (bp->b_vflags & BV_BKGRDINPROG)
1801 panic("losing buffer 2");
1802 qindex = QUEUE_CLEAN;
1803 bp->b_flags |= B_AGE;
1804 /* remaining buffers */
1805 } else if (bp->b_flags & B_DELWRI)
1806 qindex = QUEUE_DIRTY;
1808 qindex = QUEUE_CLEAN;
1810 binsfree(bp, qindex);
1812 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF | B_DIRECT);
1813 if ((bp->b_flags & B_DELWRI) == 0 && (bp->b_xflags & BX_VNDIRTY))
1814 panic("brelse: not dirty");
1820 * Release a buffer back to the appropriate queue but do not try to free
1821 * it. The buffer is expected to be used again soon.
1823 * bqrelse() is used by bdwrite() to requeue a delayed write, and used by
1824 * biodone() to requeue an async I/O on completion. It is also used when
1825 * known good buffers need to be requeued but we think we may need the data
1828 * XXX we should be able to leave the B_RELBUF hint set on completion.
1831 bqrelse(struct buf *bp)
1835 CTR3(KTR_BUF, "bqrelse(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
1836 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)),
1837 ("bqrelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp));
1839 if (BUF_LOCKRECURSED(bp)) {
1840 /* do not release to free list */
1844 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF);
1846 if (bp->b_flags & B_MANAGED) {
1847 if (bp->b_flags & B_REMFREE)
1852 /* buffers with stale but valid contents */
1853 if (bp->b_flags & B_DELWRI) {
1854 qindex = QUEUE_DIRTY;
1856 if ((bp->b_flags & B_DELWRI) == 0 &&
1857 (bp->b_xflags & BX_VNDIRTY))
1858 panic("bqrelse: not dirty");
1860 * BKGRDINPROG can only be set with the buf and bufobj
1861 * locks both held. We tolerate a race to clear it here.
1863 if (buf_vm_page_count_severe() &&
1864 (bp->b_vflags & BV_BKGRDINPROG) == 0) {
1866 * We are too low on memory, we have to try to free
1867 * the buffer (most importantly: the wired pages
1868 * making up its backing store) *now*.
1873 qindex = QUEUE_CLEAN;
1875 binsfree(bp, qindex);
1882 /* Give pages used by the bp back to the VM system (where possible) */
1884 vfs_vmio_release(struct buf *bp)
1890 if ((bp->b_flags & B_UNMAPPED) == 0) {
1891 BUF_CHECK_MAPPED(bp);
1892 pmap_qremove(trunc_page((vm_offset_t)bp->b_data), bp->b_npages);
1894 BUF_CHECK_UNMAPPED(bp);
1895 obj = bp->b_bufobj->bo_object;
1897 VM_OBJECT_WLOCK(obj);
1898 for (i = 0; i < bp->b_npages; i++) {
1900 bp->b_pages[i] = NULL;
1902 * In order to keep page LRU ordering consistent, put
1903 * everything on the inactive queue.
1906 vm_page_unwire(m, PQ_INACTIVE);
1909 * Might as well free the page if we can and it has
1910 * no valid data. We also free the page if the
1911 * buffer was used for direct I/O
1913 if ((bp->b_flags & B_ASYNC) == 0 && !m->valid) {
1914 if (m->wire_count == 0 && !vm_page_busied(m))
1916 } else if (bp->b_flags & B_DIRECT)
1917 vm_page_try_to_free(m);
1918 else if (buf_vm_page_count_severe())
1919 vm_page_try_to_cache(m);
1923 VM_OBJECT_WUNLOCK(obj);
1925 if (bp->b_bufsize) {
1930 bp->b_flags &= ~B_VMIO;
1936 * Check to see if a block at a particular lbn is available for a clustered
1940 vfs_bio_clcheck(struct vnode *vp, int size, daddr_t lblkno, daddr_t blkno)
1947 /* If the buf isn't in core skip it */
1948 if ((bpa = gbincore(&vp->v_bufobj, lblkno)) == NULL)
1951 /* If the buf is busy we don't want to wait for it */
1952 if (BUF_LOCK(bpa, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0)
1955 /* Only cluster with valid clusterable delayed write buffers */
1956 if ((bpa->b_flags & (B_DELWRI | B_CLUSTEROK | B_INVAL)) !=
1957 (B_DELWRI | B_CLUSTEROK))
1960 if (bpa->b_bufsize != size)
1964 * Check to see if it is in the expected place on disk and that the
1965 * block has been mapped.
1967 if ((bpa->b_blkno != bpa->b_lblkno) && (bpa->b_blkno == blkno))
1977 * Implement clustered async writes for clearing out B_DELWRI buffers.
1978 * This is much better then the old way of writing only one buffer at
1979 * a time. Note that we may not be presented with the buffers in the
1980 * correct order, so we search for the cluster in both directions.
1983 vfs_bio_awrite(struct buf *bp)
1988 daddr_t lblkno = bp->b_lblkno;
1989 struct vnode *vp = bp->b_vp;
1997 gbflags = (bp->b_flags & B_UNMAPPED) != 0 ? GB_UNMAPPED : 0;
1999 * right now we support clustered writing only to regular files. If
2000 * we find a clusterable block we could be in the middle of a cluster
2001 * rather then at the beginning.
2003 if ((vp->v_type == VREG) &&
2004 (vp->v_mount != 0) && /* Only on nodes that have the size info */
2005 (bp->b_flags & (B_CLUSTEROK | B_INVAL)) == B_CLUSTEROK) {
2007 size = vp->v_mount->mnt_stat.f_iosize;
2008 maxcl = MAXPHYS / size;
2011 for (i = 1; i < maxcl; i++)
2012 if (vfs_bio_clcheck(vp, size, lblkno + i,
2013 bp->b_blkno + ((i * size) >> DEV_BSHIFT)) == 0)
2016 for (j = 1; i + j <= maxcl && j <= lblkno; j++)
2017 if (vfs_bio_clcheck(vp, size, lblkno - j,
2018 bp->b_blkno - ((j * size) >> DEV_BSHIFT)) == 0)
2024 * this is a possible cluster write
2028 nwritten = cluster_wbuild(vp, size, lblkno - j, ncl,
2034 bp->b_flags |= B_ASYNC;
2036 * default (old) behavior, writing out only one block
2038 * XXX returns b_bufsize instead of b_bcount for nwritten?
2040 nwritten = bp->b_bufsize;
2047 setbufkva(struct buf *bp, vm_offset_t addr, int maxsize, int gbflags)
2050 KASSERT((bp->b_flags & (B_UNMAPPED | B_KVAALLOC)) == 0 &&
2051 bp->b_kvasize == 0, ("call bfreekva(%p)", bp));
2052 if ((gbflags & GB_UNMAPPED) == 0) {
2053 bp->b_kvabase = (caddr_t)addr;
2054 } else if ((gbflags & GB_KVAALLOC) != 0) {
2055 KASSERT((gbflags & GB_UNMAPPED) != 0,
2056 ("GB_KVAALLOC without GB_UNMAPPED"));
2057 bp->b_kvaalloc = (caddr_t)addr;
2058 bp->b_flags |= B_UNMAPPED | B_KVAALLOC;
2059 atomic_add_long(&unmapped_bufspace, bp->b_kvasize);
2061 bp->b_kvasize = maxsize;
2065 * Allocate the buffer KVA and set b_kvasize. Also set b_kvabase if
2069 allocbufkva(struct buf *bp, int maxsize, int gbflags)
2076 if (vmem_alloc(buffer_arena, maxsize, M_BESTFIT | M_NOWAIT, &addr)) {
2078 * Buffer map is too fragmented. Request the caller
2079 * to defragment the map.
2081 atomic_add_int(&bufdefragcnt, 1);
2084 setbufkva(bp, addr, maxsize, gbflags);
2085 atomic_add_long(&bufspace, bp->b_kvasize);
2090 * Ask the bufdaemon for help, or act as bufdaemon itself, when a
2091 * locked vnode is supplied.
2094 getnewbuf_bufd_help(struct vnode *vp, int gbflags, int slpflag, int slptimeo,
2099 int cnt, error, flags, norunbuf, wait;
2101 mtx_assert(&bqclean, MA_OWNED);
2104 flags = VFS_BIO_NEED_BUFSPACE;
2106 } else if (bufspace >= hibufspace) {
2108 flags = VFS_BIO_NEED_BUFSPACE;
2111 flags = VFS_BIO_NEED_ANY;
2113 atomic_set_int(&needsbuffer, flags);
2114 mtx_unlock(&bqclean);
2116 bd_speedup(); /* heeeelp */
2117 if ((gbflags & GB_NOWAIT_BD) != 0)
2124 while ((needsbuffer & flags) != 0) {
2125 if (vp != NULL && vp->v_type != VCHR &&
2126 (td->td_pflags & TDP_BUFNEED) == 0) {
2127 rw_wunlock(&nblock);
2129 * getblk() is called with a vnode locked, and
2130 * some majority of the dirty buffers may as
2131 * well belong to the vnode. Flushing the
2132 * buffers there would make a progress that
2133 * cannot be achieved by the buf_daemon, that
2134 * cannot lock the vnode.
2138 ASSERT_VOP_LOCKED(vp, "bufd_helper");
2139 error = VOP_ISLOCKED(vp) == LK_EXCLUSIVE ? 0 :
2140 vn_lock(vp, LK_TRYUPGRADE);
2142 /* play bufdaemon */
2143 norunbuf = curthread_pflags_set(TDP_BUFNEED |
2145 VOP_FSYNC(vp, wait, td);
2146 atomic_add_long(¬bufdflushes, 1);
2147 curthread_pflags_restore(norunbuf);
2150 if ((needsbuffer & flags) == 0)
2153 error = rw_sleep(__DEVOLATILE(void *, &needsbuffer), &nblock,
2154 (PRIBIO + 4) | slpflag, waitmsg, slptimeo);
2158 rw_wunlock(&nblock);
2162 getnewbuf_reuse_bp(struct buf *bp, int qindex)
2165 CTR6(KTR_BUF, "getnewbuf(%p) vp %p flags %X kvasize %d bufsize %d "
2166 "queue %d (recycling)", bp, bp->b_vp, bp->b_flags,
2167 bp->b_kvasize, bp->b_bufsize, qindex);
2168 mtx_assert(&bqclean, MA_NOTOWNED);
2171 * Note: we no longer distinguish between VMIO and non-VMIO
2174 KASSERT((bp->b_flags & B_DELWRI) == 0,
2175 ("delwri buffer %p found in queue %d", bp, qindex));
2177 if (qindex == QUEUE_CLEAN) {
2178 if (bp->b_flags & B_VMIO) {
2179 bp->b_flags &= ~B_ASYNC;
2180 vfs_vmio_release(bp);
2182 if (bp->b_vp != NULL)
2187 * Get the rest of the buffer freed up. b_kva* is still valid
2188 * after this operation.
2191 if (bp->b_rcred != NOCRED) {
2192 crfree(bp->b_rcred);
2193 bp->b_rcred = NOCRED;
2195 if (bp->b_wcred != NOCRED) {
2196 crfree(bp->b_wcred);
2197 bp->b_wcred = NOCRED;
2199 if (!LIST_EMPTY(&bp->b_dep))
2201 if (bp->b_vflags & BV_BKGRDINPROG)
2202 panic("losing buffer 3");
2203 KASSERT(bp->b_vp == NULL, ("bp: %p still has vnode %p. qindex: %d",
2204 bp, bp->b_vp, qindex));
2205 KASSERT((bp->b_xflags & (BX_VNCLEAN|BX_VNDIRTY)) == 0,
2206 ("bp: %p still on a buffer list. xflags %X", bp, bp->b_xflags));
2211 bp->b_flags &= B_UNMAPPED | B_KVAALLOC;
2214 KASSERT((bp->b_flags & B_INFREECNT) == 0,
2215 ("buf %p still counted as free?", bp));
2218 bp->b_blkno = bp->b_lblkno = 0;
2219 bp->b_offset = NOOFFSET;
2225 bp->b_dirtyoff = bp->b_dirtyend = 0;
2226 bp->b_bufobj = NULL;
2227 bp->b_pin_count = 0;
2228 bp->b_fsprivate1 = NULL;
2229 bp->b_fsprivate2 = NULL;
2230 bp->b_fsprivate3 = NULL;
2232 LIST_INIT(&bp->b_dep);
2235 static int flushingbufs;
2238 getnewbuf_scan(int maxsize, int defrag, int unmapped, int metadata)
2240 struct buf *bp, *nbp;
2241 int nqindex, qindex, pass;
2243 KASSERT(!unmapped || !defrag, ("both unmapped and defrag"));
2247 atomic_add_int(&getnewbufrestarts, 1);
2250 * Setup for scan. If we do not have enough free buffers,
2251 * we setup a degenerate case that immediately fails. Note
2252 * that if we are specially marked process, we are allowed to
2253 * dip into our reserves.
2255 * The scanning sequence is nominally: EMPTY->EMPTYKVA->CLEAN
2256 * for the allocation of the mapped buffer. For unmapped, the
2257 * easiest is to start with EMPTY outright.
2259 * We start with EMPTYKVA. If the list is empty we backup to EMPTY.
2260 * However, there are a number of cases (defragging, reusing, ...)
2261 * where we cannot backup.
2265 if (!defrag && unmapped) {
2266 nqindex = QUEUE_EMPTY;
2267 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTY]);
2270 nqindex = QUEUE_EMPTYKVA;
2271 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTYKVA]);
2275 * If no EMPTYKVA buffers and we are either defragging or
2276 * reusing, locate a CLEAN buffer to free or reuse. If
2277 * bufspace useage is low skip this step so we can allocate a
2280 if (nbp == NULL && (defrag || bufspace >= lobufspace)) {
2281 nqindex = QUEUE_CLEAN;
2282 nbp = TAILQ_FIRST(&bufqueues[QUEUE_CLEAN]);
2286 * If we could not find or were not allowed to reuse a CLEAN
2287 * buffer, check to see if it is ok to use an EMPTY buffer.
2288 * We can only use an EMPTY buffer if allocating its KVA would
2289 * not otherwise run us out of buffer space. No KVA is needed
2290 * for the unmapped allocation.
2292 if (nbp == NULL && defrag == 0 && (bufspace + maxsize < hibufspace ||
2294 nqindex = QUEUE_EMPTY;
2295 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTY]);
2299 * All available buffers might be clean, retry ignoring the
2300 * lobufspace as the last resort.
2302 if (nbp == NULL && !TAILQ_EMPTY(&bufqueues[QUEUE_CLEAN])) {
2303 nqindex = QUEUE_CLEAN;
2304 nbp = TAILQ_FIRST(&bufqueues[QUEUE_CLEAN]);
2308 * Run scan, possibly freeing data and/or kva mappings on the fly
2311 while ((bp = nbp) != NULL) {
2315 * Calculate next bp (we can only use it if we do not
2316 * block or do other fancy things).
2318 if ((nbp = TAILQ_NEXT(bp, b_freelist)) == NULL) {
2321 nqindex = QUEUE_EMPTYKVA;
2322 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTYKVA]);
2326 case QUEUE_EMPTYKVA:
2327 nqindex = QUEUE_CLEAN;
2328 nbp = TAILQ_FIRST(&bufqueues[QUEUE_CLEAN]);
2333 if (metadata && pass == 1) {
2335 nqindex = QUEUE_EMPTY;
2337 &bufqueues[QUEUE_EMPTY]);
2346 * If we are defragging then we need a buffer with
2347 * b_kvasize != 0. XXX this situation should no longer
2348 * occur, if defrag is non-zero the buffer's b_kvasize
2349 * should also be non-zero at this point. XXX
2351 if (defrag && bp->b_kvasize == 0) {
2352 printf("Warning: defrag empty buffer %p\n", bp);
2357 * Start freeing the bp. This is somewhat involved. nbp
2358 * remains valid only for QUEUE_EMPTY[KVA] bp's.
2360 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0)
2363 * BKGRDINPROG can only be set with the buf and bufobj
2364 * locks both held. We tolerate a race to clear it here.
2366 if (bp->b_vflags & BV_BKGRDINPROG) {
2371 KASSERT(bp->b_qindex == qindex,
2372 ("getnewbuf: inconsistent queue %d bp %p", qindex, bp));
2375 mtx_unlock(&bqclean);
2377 * NOTE: nbp is now entirely invalid. We can only restart
2378 * the scan from this point on.
2381 getnewbuf_reuse_bp(bp, qindex);
2382 mtx_assert(&bqclean, MA_NOTOWNED);
2385 * If we are defragging then free the buffer.
2388 bp->b_flags |= B_INVAL;
2396 * Notify any waiters for the buffer lock about
2397 * identity change by freeing the buffer.
2399 if (qindex == QUEUE_CLEAN && BUF_LOCKWAITERS(bp)) {
2400 bp->b_flags |= B_INVAL;
2410 * If we are overcomitted then recover the buffer and its
2411 * KVM space. This occurs in rare situations when multiple
2412 * processes are blocked in getnewbuf() or allocbuf().
2414 if (bufspace >= hibufspace)
2416 if (flushingbufs && bp->b_kvasize != 0) {
2417 bp->b_flags |= B_INVAL;
2422 if (bufspace < lobufspace)
2432 * Find and initialize a new buffer header, freeing up existing buffers
2433 * in the bufqueues as necessary. The new buffer is returned locked.
2435 * Important: B_INVAL is not set. If the caller wishes to throw the
2436 * buffer away, the caller must set B_INVAL prior to calling brelse().
2439 * We have insufficient buffer headers
2440 * We have insufficient buffer space
2441 * buffer_arena is too fragmented ( space reservation fails )
2442 * If we have to flush dirty buffers ( but we try to avoid this )
2445 getnewbuf(struct vnode *vp, int slpflag, int slptimeo, int size, int maxsize,
2449 int defrag, metadata;
2451 KASSERT((gbflags & (GB_UNMAPPED | GB_KVAALLOC)) != GB_KVAALLOC,
2452 ("GB_KVAALLOC only makes sense with GB_UNMAPPED"));
2453 if (!unmapped_buf_allowed)
2454 gbflags &= ~(GB_UNMAPPED | GB_KVAALLOC);
2457 if (vp == NULL || (vp->v_vflag & (VV_MD | VV_SYSTEM)) != 0 ||
2463 * We can't afford to block since we might be holding a vnode lock,
2464 * which may prevent system daemons from running. We deal with
2465 * low-memory situations by proactively returning memory and running
2466 * async I/O rather then sync I/O.
2468 atomic_add_int(&getnewbufcalls, 1);
2469 atomic_subtract_int(&getnewbufrestarts, 1);
2471 bp = getnewbuf_scan(maxsize, defrag, (gbflags & (GB_UNMAPPED |
2472 GB_KVAALLOC)) == GB_UNMAPPED, metadata);
2477 * If we exhausted our list, sleep as appropriate. We may have to
2478 * wakeup various daemons and write out some dirty buffers.
2480 * Generally we are sleeping due to insufficient buffer space.
2483 mtx_assert(&bqclean, MA_OWNED);
2484 getnewbuf_bufd_help(vp, gbflags, slpflag, slptimeo, defrag);
2485 mtx_assert(&bqclean, MA_NOTOWNED);
2486 } else if ((gbflags & (GB_UNMAPPED | GB_KVAALLOC)) == GB_UNMAPPED) {
2487 mtx_assert(&bqclean, MA_NOTOWNED);
2490 bp->b_flags |= B_UNMAPPED;
2491 bp->b_kvabase = bp->b_data = unmapped_buf;
2492 bp->b_kvasize = maxsize;
2493 atomic_add_long(&bufspace, bp->b_kvasize);
2494 atomic_add_long(&unmapped_bufspace, bp->b_kvasize);
2495 atomic_add_int(&bufreusecnt, 1);
2497 mtx_assert(&bqclean, MA_NOTOWNED);
2500 * We finally have a valid bp. We aren't quite out of the
2501 * woods, we still have to reserve kva space. In order
2502 * to keep fragmentation sane we only allocate kva in
2505 maxsize = (maxsize + BKVAMASK) & ~BKVAMASK;
2507 if (maxsize != bp->b_kvasize || (bp->b_flags & (B_UNMAPPED |
2508 B_KVAALLOC)) == B_UNMAPPED) {
2509 if (allocbufkva(bp, maxsize, gbflags)) {
2511 bp->b_flags |= B_INVAL;
2515 atomic_add_int(&bufreusecnt, 1);
2516 } else if ((bp->b_flags & B_KVAALLOC) != 0 &&
2517 (gbflags & (GB_UNMAPPED | GB_KVAALLOC)) == 0) {
2519 * If the reused buffer has KVA allocated,
2520 * reassign b_kvaalloc to b_kvabase.
2522 bp->b_kvabase = bp->b_kvaalloc;
2523 bp->b_flags &= ~B_KVAALLOC;
2524 atomic_subtract_long(&unmapped_bufspace,
2526 atomic_add_int(&bufreusecnt, 1);
2527 } else if ((bp->b_flags & (B_UNMAPPED | B_KVAALLOC)) == 0 &&
2528 (gbflags & (GB_UNMAPPED | GB_KVAALLOC)) == (GB_UNMAPPED |
2531 * The case of reused buffer already have KVA
2532 * mapped, but the request is for unmapped
2533 * buffer with KVA allocated.
2535 bp->b_kvaalloc = bp->b_kvabase;
2536 bp->b_data = bp->b_kvabase = unmapped_buf;
2537 bp->b_flags |= B_UNMAPPED | B_KVAALLOC;
2538 atomic_add_long(&unmapped_bufspace,
2540 atomic_add_int(&bufreusecnt, 1);
2542 if ((gbflags & GB_UNMAPPED) == 0) {
2543 bp->b_saveaddr = bp->b_kvabase;
2544 bp->b_data = bp->b_saveaddr;
2545 bp->b_flags &= ~B_UNMAPPED;
2546 BUF_CHECK_MAPPED(bp);
2555 * buffer flushing daemon. Buffers are normally flushed by the
2556 * update daemon but if it cannot keep up this process starts to
2557 * take the load in an attempt to prevent getnewbuf() from blocking.
2560 static struct kproc_desc buf_kp = {
2565 SYSINIT(bufdaemon, SI_SUB_KTHREAD_BUF, SI_ORDER_FIRST, kproc_start, &buf_kp);
2568 buf_flush(int target)
2572 flushed = flushbufqueues(target, 0);
2575 * Could not find any buffers without rollback
2576 * dependencies, so just write the first one
2577 * in the hopes of eventually making progress.
2579 flushed = flushbufqueues(target, 1);
2590 * This process needs to be suspended prior to shutdown sync.
2592 EVENTHANDLER_REGISTER(shutdown_pre_sync, kproc_shutdown, bufdaemonproc,
2596 * This process is allowed to take the buffer cache to the limit
2598 curthread->td_pflags |= TDP_NORUNNINGBUF | TDP_BUFNEED;
2602 mtx_unlock(&bdlock);
2604 kproc_suspend_check(bufdaemonproc);
2605 lodirty = lodirtybuffers;
2606 if (bd_speedupreq) {
2607 lodirty = numdirtybuffers / 2;
2611 * Do the flush. Limit the amount of in-transit I/O we
2612 * allow to build up, otherwise we would completely saturate
2615 while (numdirtybuffers > lodirty) {
2616 if (buf_flush(numdirtybuffers - lodirty) == 0)
2618 kern_yield(PRI_USER);
2622 * Only clear bd_request if we have reached our low water
2623 * mark. The buf_daemon normally waits 1 second and
2624 * then incrementally flushes any dirty buffers that have
2625 * built up, within reason.
2627 * If we were unable to hit our low water mark and couldn't
2628 * find any flushable buffers, we sleep for a short period
2629 * to avoid endless loops on unlockable buffers.
2632 if (numdirtybuffers <= lodirtybuffers) {
2634 * We reached our low water mark, reset the
2635 * request and sleep until we are needed again.
2636 * The sleep is just so the suspend code works.
2640 * Do an extra wakeup in case dirty threshold
2641 * changed via sysctl and the explicit transition
2642 * out of shortfall was missed.
2645 if (runningbufspace <= lorunningspace)
2647 msleep(&bd_request, &bdlock, PVM, "psleep", hz);
2650 * We couldn't find any flushable dirty buffers but
2651 * still have too many dirty buffers, we
2652 * have to sleep and try again. (rare)
2654 msleep(&bd_request, &bdlock, PVM, "qsleep", hz / 10);
2662 * Try to flush a buffer in the dirty queue. We must be careful to
2663 * free up B_INVAL buffers instead of write them, which NFS is
2664 * particularly sensitive to.
2666 static int flushwithdeps = 0;
2667 SYSCTL_INT(_vfs, OID_AUTO, flushwithdeps, CTLFLAG_RW, &flushwithdeps,
2668 0, "Number of buffers flushed with dependecies that require rollbacks");
2671 flushbufqueues(int target, int flushdeps)
2673 struct buf *sentinel;
2683 queue = QUEUE_DIRTY;
2685 sentinel = malloc(sizeof(struct buf), M_TEMP, M_WAITOK | M_ZERO);
2686 sentinel->b_qindex = QUEUE_SENTINEL;
2688 TAILQ_INSERT_HEAD(&bufqueues[queue], sentinel, b_freelist);
2689 mtx_unlock(&bqdirty);
2690 while (flushed != target) {
2693 bp = TAILQ_NEXT(sentinel, b_freelist);
2695 TAILQ_REMOVE(&bufqueues[queue], sentinel, b_freelist);
2696 TAILQ_INSERT_AFTER(&bufqueues[queue], bp, sentinel,
2699 mtx_unlock(&bqdirty);
2702 KASSERT(bp->b_qindex != QUEUE_SENTINEL,
2703 ("parallel calls to flushbufqueues() bp %p", bp));
2704 error = BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL);
2705 mtx_unlock(&bqdirty);
2708 if (bp->b_pin_count > 0) {
2713 * BKGRDINPROG can only be set with the buf and bufobj
2714 * locks both held. We tolerate a race to clear it here.
2716 if ((bp->b_vflags & BV_BKGRDINPROG) != 0 ||
2717 (bp->b_flags & B_DELWRI) == 0) {
2721 if (bp->b_flags & B_INVAL) {
2728 if (!LIST_EMPTY(&bp->b_dep) && buf_countdeps(bp, 0)) {
2729 if (flushdeps == 0) {
2737 * We must hold the lock on a vnode before writing
2738 * one of its buffers. Otherwise we may confuse, or
2739 * in the case of a snapshot vnode, deadlock the
2742 * The lock order here is the reverse of the normal
2743 * of vnode followed by buf lock. This is ok because
2744 * the NOWAIT will prevent deadlock.
2747 if (vn_start_write(vp, &mp, V_NOWAIT) != 0) {
2751 error = vn_lock(vp, LK_EXCLUSIVE | LK_NOWAIT);
2753 CTR3(KTR_BUF, "flushbufqueue(%p) vp %p flags %X",
2754 bp, bp->b_vp, bp->b_flags);
2756 vn_finished_write(mp);
2758 flushwithdeps += hasdeps;
2760 if (runningbufspace > hirunningspace)
2761 waitrunningbufspace();
2764 vn_finished_write(mp);
2768 TAILQ_REMOVE(&bufqueues[queue], sentinel, b_freelist);
2769 mtx_unlock(&bqdirty);
2770 free(sentinel, M_TEMP);
2775 * Check to see if a block is currently memory resident.
2778 incore(struct bufobj *bo, daddr_t blkno)
2783 bp = gbincore(bo, blkno);
2789 * Returns true if no I/O is needed to access the
2790 * associated VM object. This is like incore except
2791 * it also hunts around in the VM system for the data.
2795 inmem(struct vnode * vp, daddr_t blkno)
2798 vm_offset_t toff, tinc, size;
2802 ASSERT_VOP_LOCKED(vp, "inmem");
2804 if (incore(&vp->v_bufobj, blkno))
2806 if (vp->v_mount == NULL)
2813 if (size > vp->v_mount->mnt_stat.f_iosize)
2814 size = vp->v_mount->mnt_stat.f_iosize;
2815 off = (vm_ooffset_t)blkno * (vm_ooffset_t)vp->v_mount->mnt_stat.f_iosize;
2817 VM_OBJECT_RLOCK(obj);
2818 for (toff = 0; toff < vp->v_mount->mnt_stat.f_iosize; toff += tinc) {
2819 m = vm_page_lookup(obj, OFF_TO_IDX(off + toff));
2823 if (tinc > PAGE_SIZE - ((toff + off) & PAGE_MASK))
2824 tinc = PAGE_SIZE - ((toff + off) & PAGE_MASK);
2825 if (vm_page_is_valid(m,
2826 (vm_offset_t) ((toff + off) & PAGE_MASK), tinc) == 0)
2829 VM_OBJECT_RUNLOCK(obj);
2833 VM_OBJECT_RUNLOCK(obj);
2838 * Set the dirty range for a buffer based on the status of the dirty
2839 * bits in the pages comprising the buffer. The range is limited
2840 * to the size of the buffer.
2842 * Tell the VM system that the pages associated with this buffer
2843 * are clean. This is used for delayed writes where the data is
2844 * going to go to disk eventually without additional VM intevention.
2846 * Note that while we only really need to clean through to b_bcount, we
2847 * just go ahead and clean through to b_bufsize.
2850 vfs_clean_pages_dirty_buf(struct buf *bp)
2852 vm_ooffset_t foff, noff, eoff;
2856 if ((bp->b_flags & B_VMIO) == 0 || bp->b_bufsize == 0)
2859 foff = bp->b_offset;
2860 KASSERT(bp->b_offset != NOOFFSET,
2861 ("vfs_clean_pages_dirty_buf: no buffer offset"));
2863 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object);
2864 vfs_drain_busy_pages(bp);
2865 vfs_setdirty_locked_object(bp);
2866 for (i = 0; i < bp->b_npages; i++) {
2867 noff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK;
2869 if (eoff > bp->b_offset + bp->b_bufsize)
2870 eoff = bp->b_offset + bp->b_bufsize;
2872 vfs_page_set_validclean(bp, foff, m);
2873 /* vm_page_clear_dirty(m, foff & PAGE_MASK, eoff - foff); */
2876 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object);
2880 vfs_setdirty_locked_object(struct buf *bp)
2885 object = bp->b_bufobj->bo_object;
2886 VM_OBJECT_ASSERT_WLOCKED(object);
2889 * We qualify the scan for modified pages on whether the
2890 * object has been flushed yet.
2892 if ((object->flags & OBJ_MIGHTBEDIRTY) != 0) {
2893 vm_offset_t boffset;
2894 vm_offset_t eoffset;
2897 * test the pages to see if they have been modified directly
2898 * by users through the VM system.
2900 for (i = 0; i < bp->b_npages; i++)
2901 vm_page_test_dirty(bp->b_pages[i]);
2904 * Calculate the encompassing dirty range, boffset and eoffset,
2905 * (eoffset - boffset) bytes.
2908 for (i = 0; i < bp->b_npages; i++) {
2909 if (bp->b_pages[i]->dirty)
2912 boffset = (i << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK);
2914 for (i = bp->b_npages - 1; i >= 0; --i) {
2915 if (bp->b_pages[i]->dirty) {
2919 eoffset = ((i + 1) << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK);
2922 * Fit it to the buffer.
2925 if (eoffset > bp->b_bcount)
2926 eoffset = bp->b_bcount;
2929 * If we have a good dirty range, merge with the existing
2933 if (boffset < eoffset) {
2934 if (bp->b_dirtyoff > boffset)
2935 bp->b_dirtyoff = boffset;
2936 if (bp->b_dirtyend < eoffset)
2937 bp->b_dirtyend = eoffset;
2943 * Allocate the KVA mapping for an existing buffer. It handles the
2944 * cases of both B_UNMAPPED buffer, and buffer with the preallocated
2945 * KVA which is not mapped (B_KVAALLOC).
2948 bp_unmapped_get_kva(struct buf *bp, daddr_t blkno, int size, int gbflags)
2950 struct buf *scratch_bp;
2951 int bsize, maxsize, need_mapping, need_kva;
2954 need_mapping = (bp->b_flags & B_UNMAPPED) != 0 &&
2955 (gbflags & GB_UNMAPPED) == 0;
2956 need_kva = (bp->b_flags & (B_KVAALLOC | B_UNMAPPED)) == B_UNMAPPED &&
2957 (gbflags & GB_KVAALLOC) != 0;
2958 if (!need_mapping && !need_kva)
2961 BUF_CHECK_UNMAPPED(bp);
2963 if (need_mapping && (bp->b_flags & B_KVAALLOC) != 0) {
2965 * Buffer is not mapped, but the KVA was already
2966 * reserved at the time of the instantiation. Use the
2969 bp->b_flags &= ~B_KVAALLOC;
2970 KASSERT(bp->b_kvaalloc != 0, ("kvaalloc == 0"));
2971 bp->b_kvabase = bp->b_kvaalloc;
2972 atomic_subtract_long(&unmapped_bufspace, bp->b_kvasize);
2977 * Calculate the amount of the address space we would reserve
2978 * if the buffer was mapped.
2980 bsize = vn_isdisk(bp->b_vp, NULL) ? DEV_BSIZE : bp->b_bufobj->bo_bsize;
2981 KASSERT(bsize != 0, ("bsize == 0, check bo->bo_bsize"));
2982 offset = blkno * bsize;
2983 maxsize = size + (offset & PAGE_MASK);
2984 maxsize = imax(maxsize, bsize);
2987 if (allocbufkva(bp, maxsize, gbflags)) {
2989 * Request defragmentation. getnewbuf() returns us the
2990 * allocated space by the scratch buffer KVA.
2992 scratch_bp = getnewbuf(bp->b_vp, 0, 0, size, maxsize, gbflags |
2993 (GB_UNMAPPED | GB_KVAALLOC));
2994 if (scratch_bp == NULL) {
2995 if ((gbflags & GB_NOWAIT_BD) != 0) {
2997 * XXXKIB: defragmentation cannot
2998 * succeed, not sure what else to do.
3000 panic("GB_NOWAIT_BD and B_UNMAPPED %p", bp);
3002 atomic_add_int(&mappingrestarts, 1);
3005 KASSERT((scratch_bp->b_flags & B_KVAALLOC) != 0,
3006 ("scratch bp !B_KVAALLOC %p", scratch_bp));
3007 setbufkva(bp, (vm_offset_t)scratch_bp->b_kvaalloc,
3008 scratch_bp->b_kvasize, gbflags);
3010 /* Get rid of the scratch buffer. */
3011 scratch_bp->b_kvasize = 0;
3012 scratch_bp->b_flags |= B_INVAL;
3013 scratch_bp->b_flags &= ~(B_UNMAPPED | B_KVAALLOC);
3020 bp->b_saveaddr = bp->b_kvabase;
3021 bp->b_data = bp->b_saveaddr; /* b_offset is handled by bpmap_qenter */
3022 bp->b_flags &= ~B_UNMAPPED;
3023 BUF_CHECK_MAPPED(bp);
3030 * Get a block given a specified block and offset into a file/device.
3031 * The buffers B_DONE bit will be cleared on return, making it almost
3032 * ready for an I/O initiation. B_INVAL may or may not be set on
3033 * return. The caller should clear B_INVAL prior to initiating a
3036 * For a non-VMIO buffer, B_CACHE is set to the opposite of B_INVAL for
3037 * an existing buffer.
3039 * For a VMIO buffer, B_CACHE is modified according to the backing VM.
3040 * If getblk()ing a previously 0-sized invalid buffer, B_CACHE is set
3041 * and then cleared based on the backing VM. If the previous buffer is
3042 * non-0-sized but invalid, B_CACHE will be cleared.
3044 * If getblk() must create a new buffer, the new buffer is returned with
3045 * both B_INVAL and B_CACHE clear unless it is a VMIO buffer, in which
3046 * case it is returned with B_INVAL clear and B_CACHE set based on the
3049 * getblk() also forces a bwrite() for any B_DELWRI buffer whos
3050 * B_CACHE bit is clear.
3052 * What this means, basically, is that the caller should use B_CACHE to
3053 * determine whether the buffer is fully valid or not and should clear
3054 * B_INVAL prior to issuing a read. If the caller intends to validate
3055 * the buffer by loading its data area with something, the caller needs
3056 * to clear B_INVAL. If the caller does this without issuing an I/O,
3057 * the caller should set B_CACHE ( as an optimization ), else the caller
3058 * should issue the I/O and biodone() will set B_CACHE if the I/O was
3059 * a write attempt or if it was a successfull read. If the caller
3060 * intends to issue a READ, the caller must clear B_INVAL and BIO_ERROR
3061 * prior to issuing the READ. biodone() will *not* clear B_INVAL.
3064 getblk(struct vnode *vp, daddr_t blkno, int size, int slpflag, int slptimeo,
3069 int bsize, error, maxsize, vmio;
3072 CTR3(KTR_BUF, "getblk(%p, %ld, %d)", vp, (long)blkno, size);
3073 KASSERT((flags & (GB_UNMAPPED | GB_KVAALLOC)) != GB_KVAALLOC,
3074 ("GB_KVAALLOC only makes sense with GB_UNMAPPED"));
3075 ASSERT_VOP_LOCKED(vp, "getblk");
3076 if (size > MAXBSIZE)
3077 panic("getblk: size(%d) > MAXBSIZE(%d)\n", size, MAXBSIZE);
3078 if (!unmapped_buf_allowed)
3079 flags &= ~(GB_UNMAPPED | GB_KVAALLOC);
3084 bp = gbincore(bo, blkno);
3088 * Buffer is in-core. If the buffer is not busy nor managed,
3089 * it must be on a queue.
3091 lockflags = LK_EXCLUSIVE | LK_SLEEPFAIL | LK_INTERLOCK;
3093 if (flags & GB_LOCK_NOWAIT)
3094 lockflags |= LK_NOWAIT;
3096 error = BUF_TIMELOCK(bp, lockflags,
3097 BO_LOCKPTR(bo), "getblk", slpflag, slptimeo);
3100 * If we slept and got the lock we have to restart in case
3101 * the buffer changed identities.
3103 if (error == ENOLCK)
3105 /* We timed out or were interrupted. */
3108 /* If recursed, assume caller knows the rules. */
3109 else if (BUF_LOCKRECURSED(bp))
3113 * The buffer is locked. B_CACHE is cleared if the buffer is
3114 * invalid. Otherwise, for a non-VMIO buffer, B_CACHE is set
3115 * and for a VMIO buffer B_CACHE is adjusted according to the
3118 if (bp->b_flags & B_INVAL)
3119 bp->b_flags &= ~B_CACHE;
3120 else if ((bp->b_flags & (B_VMIO | B_INVAL)) == 0)
3121 bp->b_flags |= B_CACHE;
3122 if (bp->b_flags & B_MANAGED)
3123 MPASS(bp->b_qindex == QUEUE_NONE);
3128 * check for size inconsistencies for non-VMIO case.
3130 if (bp->b_bcount != size) {
3131 if ((bp->b_flags & B_VMIO) == 0 ||
3132 (size > bp->b_kvasize)) {
3133 if (bp->b_flags & B_DELWRI) {
3135 * If buffer is pinned and caller does
3136 * not want sleep waiting for it to be
3137 * unpinned, bail out
3139 if (bp->b_pin_count > 0) {
3140 if (flags & GB_LOCK_NOWAIT) {
3147 bp->b_flags |= B_NOCACHE;
3150 if (LIST_EMPTY(&bp->b_dep)) {
3151 bp->b_flags |= B_RELBUF;
3154 bp->b_flags |= B_NOCACHE;
3163 * Handle the case of unmapped buffer which should
3164 * become mapped, or the buffer for which KVA
3165 * reservation is requested.
3167 bp_unmapped_get_kva(bp, blkno, size, flags);
3170 * If the size is inconsistant in the VMIO case, we can resize
3171 * the buffer. This might lead to B_CACHE getting set or
3172 * cleared. If the size has not changed, B_CACHE remains
3173 * unchanged from its previous state.
3175 if (bp->b_bcount != size)
3178 KASSERT(bp->b_offset != NOOFFSET,
3179 ("getblk: no buffer offset"));
3182 * A buffer with B_DELWRI set and B_CACHE clear must
3183 * be committed before we can return the buffer in
3184 * order to prevent the caller from issuing a read
3185 * ( due to B_CACHE not being set ) and overwriting
3188 * Most callers, including NFS and FFS, need this to
3189 * operate properly either because they assume they
3190 * can issue a read if B_CACHE is not set, or because
3191 * ( for example ) an uncached B_DELWRI might loop due
3192 * to softupdates re-dirtying the buffer. In the latter
3193 * case, B_CACHE is set after the first write completes,
3194 * preventing further loops.
3195 * NOTE! b*write() sets B_CACHE. If we cleared B_CACHE
3196 * above while extending the buffer, we cannot allow the
3197 * buffer to remain with B_CACHE set after the write
3198 * completes or it will represent a corrupt state. To
3199 * deal with this we set B_NOCACHE to scrap the buffer
3202 * We might be able to do something fancy, like setting
3203 * B_CACHE in bwrite() except if B_DELWRI is already set,
3204 * so the below call doesn't set B_CACHE, but that gets real
3205 * confusing. This is much easier.
3208 if ((bp->b_flags & (B_CACHE|B_DELWRI)) == B_DELWRI) {
3209 bp->b_flags |= B_NOCACHE;
3213 bp->b_flags &= ~B_DONE;
3216 * Buffer is not in-core, create new buffer. The buffer
3217 * returned by getnewbuf() is locked. Note that the returned
3218 * buffer is also considered valid (not marked B_INVAL).
3222 * If the user does not want us to create the buffer, bail out
3225 if (flags & GB_NOCREAT)
3227 if (numfreebuffers == 0 && TD_IS_IDLETHREAD(curthread))
3230 bsize = vn_isdisk(vp, NULL) ? DEV_BSIZE : bo->bo_bsize;
3231 KASSERT(bsize != 0, ("bsize == 0, check bo->bo_bsize"));
3232 offset = blkno * bsize;
3233 vmio = vp->v_object != NULL;
3235 maxsize = size + (offset & PAGE_MASK);
3238 /* Do not allow non-VMIO notmapped buffers. */
3239 flags &= ~GB_UNMAPPED;
3241 maxsize = imax(maxsize, bsize);
3243 bp = getnewbuf(vp, slpflag, slptimeo, size, maxsize, flags);
3245 if (slpflag || slptimeo)
3251 * This code is used to make sure that a buffer is not
3252 * created while the getnewbuf routine is blocked.
3253 * This can be a problem whether the vnode is locked or not.
3254 * If the buffer is created out from under us, we have to
3255 * throw away the one we just created.
3257 * Note: this must occur before we associate the buffer
3258 * with the vp especially considering limitations in
3259 * the splay tree implementation when dealing with duplicate
3263 if (gbincore(bo, blkno)) {
3265 bp->b_flags |= B_INVAL;
3271 * Insert the buffer into the hash, so that it can
3272 * be found by incore.
3274 bp->b_blkno = bp->b_lblkno = blkno;
3275 bp->b_offset = offset;
3280 * set B_VMIO bit. allocbuf() the buffer bigger. Since the
3281 * buffer size starts out as 0, B_CACHE will be set by
3282 * allocbuf() for the VMIO case prior to it testing the
3283 * backing store for validity.
3287 bp->b_flags |= B_VMIO;
3288 KASSERT(vp->v_object == bp->b_bufobj->bo_object,
3289 ("ARGH! different b_bufobj->bo_object %p %p %p\n",
3290 bp, vp->v_object, bp->b_bufobj->bo_object));
3292 bp->b_flags &= ~B_VMIO;
3293 KASSERT(bp->b_bufobj->bo_object == NULL,
3294 ("ARGH! has b_bufobj->bo_object %p %p\n",
3295 bp, bp->b_bufobj->bo_object));
3296 BUF_CHECK_MAPPED(bp);
3300 bp->b_flags &= ~B_DONE;
3302 CTR4(KTR_BUF, "getblk(%p, %ld, %d) = %p", vp, (long)blkno, size, bp);
3303 BUF_ASSERT_HELD(bp);
3305 KASSERT(bp->b_bufobj == bo,
3306 ("bp %p wrong b_bufobj %p should be %p", bp, bp->b_bufobj, bo));
3311 * Get an empty, disassociated buffer of given size. The buffer is initially
3315 geteblk(int size, int flags)
3320 maxsize = (size + BKVAMASK) & ~BKVAMASK;
3321 while ((bp = getnewbuf(NULL, 0, 0, size, maxsize, flags)) == NULL) {
3322 if ((flags & GB_NOWAIT_BD) &&
3323 (curthread->td_pflags & TDP_BUFNEED) != 0)
3327 bp->b_flags |= B_INVAL; /* b_dep cleared by getnewbuf() */
3328 BUF_ASSERT_HELD(bp);
3334 * This code constitutes the buffer memory from either anonymous system
3335 * memory (in the case of non-VMIO operations) or from an associated
3336 * VM object (in the case of VMIO operations). This code is able to
3337 * resize a buffer up or down.
3339 * Note that this code is tricky, and has many complications to resolve
3340 * deadlock or inconsistant data situations. Tread lightly!!!
3341 * There are B_CACHE and B_DELWRI interactions that must be dealt with by
3342 * the caller. Calling this code willy nilly can result in the loss of data.
3344 * allocbuf() only adjusts B_CACHE for VMIO buffers. getblk() deals with
3345 * B_CACHE for the non-VMIO case.
3349 allocbuf(struct buf *bp, int size)
3351 int newbsize, mbsize;
3354 BUF_ASSERT_HELD(bp);
3356 if (bp->b_kvasize < size)
3357 panic("allocbuf: buffer too small");
3359 if ((bp->b_flags & B_VMIO) == 0) {
3363 * Just get anonymous memory from the kernel. Don't
3364 * mess with B_CACHE.
3366 mbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1);
3367 if (bp->b_flags & B_MALLOC)
3370 newbsize = round_page(size);
3372 if (newbsize < bp->b_bufsize) {
3374 * malloced buffers are not shrunk
3376 if (bp->b_flags & B_MALLOC) {
3378 bp->b_bcount = size;
3380 free(bp->b_data, M_BIOBUF);
3381 if (bp->b_bufsize) {
3382 atomic_subtract_long(
3388 bp->b_saveaddr = bp->b_kvabase;
3389 bp->b_data = bp->b_saveaddr;
3391 bp->b_flags &= ~B_MALLOC;
3395 vm_hold_free_pages(bp, newbsize);
3396 } else if (newbsize > bp->b_bufsize) {
3398 * We only use malloced memory on the first allocation.
3399 * and revert to page-allocated memory when the buffer
3403 * There is a potential smp race here that could lead
3404 * to bufmallocspace slightly passing the max. It
3405 * is probably extremely rare and not worth worrying
3408 if ( (bufmallocspace < maxbufmallocspace) &&
3409 (bp->b_bufsize == 0) &&
3410 (mbsize <= PAGE_SIZE/2)) {
3412 bp->b_data = malloc(mbsize, M_BIOBUF, M_WAITOK);
3413 bp->b_bufsize = mbsize;
3414 bp->b_bcount = size;
3415 bp->b_flags |= B_MALLOC;
3416 atomic_add_long(&bufmallocspace, mbsize);
3422 * If the buffer is growing on its other-than-first allocation,
3423 * then we revert to the page-allocation scheme.
3425 if (bp->b_flags & B_MALLOC) {
3426 origbuf = bp->b_data;
3427 origbufsize = bp->b_bufsize;
3428 bp->b_data = bp->b_kvabase;
3429 if (bp->b_bufsize) {
3430 atomic_subtract_long(&bufmallocspace,
3435 bp->b_flags &= ~B_MALLOC;
3436 newbsize = round_page(newbsize);
3440 (vm_offset_t) bp->b_data + bp->b_bufsize,
3441 (vm_offset_t) bp->b_data + newbsize);
3443 bcopy(origbuf, bp->b_data, origbufsize);
3444 free(origbuf, M_BIOBUF);
3450 newbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1);
3451 desiredpages = (size == 0) ? 0 :
3452 num_pages((bp->b_offset & PAGE_MASK) + newbsize);
3454 if (bp->b_flags & B_MALLOC)
3455 panic("allocbuf: VMIO buffer can't be malloced");
3457 * Set B_CACHE initially if buffer is 0 length or will become
3460 if (size == 0 || bp->b_bufsize == 0)
3461 bp->b_flags |= B_CACHE;
3463 if (newbsize < bp->b_bufsize) {
3465 * DEV_BSIZE aligned new buffer size is less then the
3466 * DEV_BSIZE aligned existing buffer size. Figure out
3467 * if we have to remove any pages.
3469 if (desiredpages < bp->b_npages) {
3472 if ((bp->b_flags & B_UNMAPPED) == 0) {
3473 BUF_CHECK_MAPPED(bp);
3474 pmap_qremove((vm_offset_t)trunc_page(
3475 (vm_offset_t)bp->b_data) +
3476 (desiredpages << PAGE_SHIFT),
3477 (bp->b_npages - desiredpages));
3479 BUF_CHECK_UNMAPPED(bp);
3480 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object);
3481 for (i = desiredpages; i < bp->b_npages; i++) {
3483 * the page is not freed here -- it
3484 * is the responsibility of
3485 * vnode_pager_setsize
3488 KASSERT(m != bogus_page,
3489 ("allocbuf: bogus page found"));
3490 while (vm_page_sleep_if_busy(m,
3494 bp->b_pages[i] = NULL;
3496 vm_page_unwire(m, PQ_INACTIVE);
3499 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object);
3500 bp->b_npages = desiredpages;
3502 } else if (size > bp->b_bcount) {
3504 * We are growing the buffer, possibly in a
3505 * byte-granular fashion.
3512 * Step 1, bring in the VM pages from the object,
3513 * allocating them if necessary. We must clear
3514 * B_CACHE if these pages are not valid for the
3515 * range covered by the buffer.
3518 obj = bp->b_bufobj->bo_object;
3520 VM_OBJECT_WLOCK(obj);
3521 while (bp->b_npages < desiredpages) {
3525 * We must allocate system pages since blocking
3526 * here could interfere with paging I/O, no
3527 * matter which process we are.
3529 * Only exclusive busy can be tested here.
3530 * Blocking on shared busy might lead to
3531 * deadlocks once allocbuf() is called after
3532 * pages are vfs_busy_pages().
3534 m = vm_page_grab(obj, OFF_TO_IDX(bp->b_offset) +
3535 bp->b_npages, VM_ALLOC_NOBUSY |
3536 VM_ALLOC_SYSTEM | VM_ALLOC_WIRED |
3537 VM_ALLOC_IGN_SBUSY |
3538 VM_ALLOC_COUNT(desiredpages - bp->b_npages));
3540 bp->b_flags &= ~B_CACHE;
3541 bp->b_pages[bp->b_npages] = m;
3546 * Step 2. We've loaded the pages into the buffer,
3547 * we have to figure out if we can still have B_CACHE
3548 * set. Note that B_CACHE is set according to the
3549 * byte-granular range ( bcount and size ), new the
3550 * aligned range ( newbsize ).
3552 * The VM test is against m->valid, which is DEV_BSIZE
3553 * aligned. Needless to say, the validity of the data
3554 * needs to also be DEV_BSIZE aligned. Note that this
3555 * fails with NFS if the server or some other client
3556 * extends the file's EOF. If our buffer is resized,
3557 * B_CACHE may remain set! XXX
3560 toff = bp->b_bcount;
3561 tinc = PAGE_SIZE - ((bp->b_offset + toff) & PAGE_MASK);
3563 while ((bp->b_flags & B_CACHE) && toff < size) {
3566 if (tinc > (size - toff))
3569 pi = ((bp->b_offset & PAGE_MASK) + toff) >>
3582 VM_OBJECT_WUNLOCK(obj);
3585 * Step 3, fixup the KVM pmap.
3587 if ((bp->b_flags & B_UNMAPPED) == 0)
3590 BUF_CHECK_UNMAPPED(bp);
3593 if (newbsize < bp->b_bufsize)
3595 bp->b_bufsize = newbsize; /* actual buffer allocation */
3596 bp->b_bcount = size; /* requested buffer size */
3600 extern int inflight_transient_maps;
3603 biodone(struct bio *bp)
3606 void (*done)(struct bio *);
3607 vm_offset_t start, end;
3609 if ((bp->bio_flags & BIO_TRANSIENT_MAPPING) != 0) {
3610 bp->bio_flags &= ~BIO_TRANSIENT_MAPPING;
3611 bp->bio_flags |= BIO_UNMAPPED;
3612 start = trunc_page((vm_offset_t)bp->bio_data);
3613 end = round_page((vm_offset_t)bp->bio_data + bp->bio_length);
3614 pmap_qremove(start, OFF_TO_IDX(end - start));
3615 vmem_free(transient_arena, start, end - start);
3616 atomic_add_int(&inflight_transient_maps, -1);
3618 done = bp->bio_done;
3620 mtxp = mtx_pool_find(mtxpool_sleep, bp);
3622 bp->bio_flags |= BIO_DONE;
3626 bp->bio_flags |= BIO_DONE;
3632 * Wait for a BIO to finish.
3635 biowait(struct bio *bp, const char *wchan)
3639 mtxp = mtx_pool_find(mtxpool_sleep, bp);
3641 while ((bp->bio_flags & BIO_DONE) == 0)
3642 msleep(bp, mtxp, PRIBIO, wchan, 0);
3644 if (bp->bio_error != 0)
3645 return (bp->bio_error);
3646 if (!(bp->bio_flags & BIO_ERROR))
3652 biofinish(struct bio *bp, struct devstat *stat, int error)
3656 bp->bio_error = error;
3657 bp->bio_flags |= BIO_ERROR;
3660 devstat_end_transaction_bio(stat, bp);
3667 * Wait for buffer I/O completion, returning error status. The buffer
3668 * is left locked and B_DONE on return. B_EINTR is converted into an EINTR
3669 * error and cleared.
3672 bufwait(struct buf *bp)
3674 if (bp->b_iocmd == BIO_READ)
3675 bwait(bp, PRIBIO, "biord");
3677 bwait(bp, PRIBIO, "biowr");
3678 if (bp->b_flags & B_EINTR) {
3679 bp->b_flags &= ~B_EINTR;
3682 if (bp->b_ioflags & BIO_ERROR) {
3683 return (bp->b_error ? bp->b_error : EIO);
3690 * Call back function from struct bio back up to struct buf.
3693 bufdonebio(struct bio *bip)
3697 bp = bip->bio_caller2;
3698 bp->b_resid = bip->bio_resid;
3699 bp->b_ioflags = bip->bio_flags;
3700 bp->b_error = bip->bio_error;
3702 bp->b_ioflags |= BIO_ERROR;
3708 dev_strategy(struct cdev *dev, struct buf *bp)
3713 KASSERT(dev->si_refcount > 0,
3714 ("dev_strategy on un-referenced struct cdev *(%s) %p",
3715 devtoname(dev), dev));
3717 csw = dev_refthread(dev, &ref);
3718 dev_strategy_csw(dev, csw, bp);
3719 dev_relthread(dev, ref);
3723 dev_strategy_csw(struct cdev *dev, struct cdevsw *csw, struct buf *bp)
3727 KASSERT(bp->b_iocmd == BIO_READ || bp->b_iocmd == BIO_WRITE,
3729 KASSERT(((dev->si_flags & SI_ETERNAL) != 0 && csw != NULL) ||
3730 dev->si_threadcount > 0,
3731 ("dev_strategy_csw threadcount cdev *(%s) %p", devtoname(dev),
3734 bp->b_error = ENXIO;
3735 bp->b_ioflags = BIO_ERROR;
3743 /* Try again later */
3744 tsleep(&bp, PRIBIO, "dev_strat", hz/10);
3746 bip->bio_cmd = bp->b_iocmd;
3747 bip->bio_offset = bp->b_iooffset;
3748 bip->bio_length = bp->b_bcount;
3749 bip->bio_bcount = bp->b_bcount; /* XXX: remove */
3751 bip->bio_done = bufdonebio;
3752 bip->bio_caller2 = bp;
3754 (*csw->d_strategy)(bip);
3760 * Finish I/O on a buffer, optionally calling a completion function.
3761 * This is usually called from an interrupt so process blocking is
3764 * biodone is also responsible for setting B_CACHE in a B_VMIO bp.
3765 * In a non-VMIO bp, B_CACHE will be set on the next getblk()
3766 * assuming B_INVAL is clear.
3768 * For the VMIO case, we set B_CACHE if the op was a read and no
3769 * read error occured, or if the op was a write. B_CACHE is never
3770 * set if the buffer is invalid or otherwise uncacheable.
3772 * biodone does not mess with B_INVAL, allowing the I/O routine or the
3773 * initiator to leave B_INVAL set to brelse the buffer out of existance
3774 * in the biodone routine.
3777 bufdone(struct buf *bp)
3779 struct bufobj *dropobj;
3780 void (*biodone)(struct buf *);
3782 CTR3(KTR_BUF, "bufdone(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
3785 KASSERT(!(bp->b_flags & B_DONE), ("biodone: bp %p already done", bp));
3786 BUF_ASSERT_HELD(bp);
3788 runningbufwakeup(bp);
3789 if (bp->b_iocmd == BIO_WRITE)
3790 dropobj = bp->b_bufobj;
3791 /* call optional completion function if requested */
3792 if (bp->b_iodone != NULL) {
3793 biodone = bp->b_iodone;
3794 bp->b_iodone = NULL;
3797 bufobj_wdrop(dropobj);
3804 bufobj_wdrop(dropobj);
3808 bufdone_finish(struct buf *bp)
3810 BUF_ASSERT_HELD(bp);
3812 if (!LIST_EMPTY(&bp->b_dep))
3815 if (bp->b_flags & B_VMIO) {
3820 int bogus, i, iosize;
3822 obj = bp->b_bufobj->bo_object;
3823 KASSERT(obj->paging_in_progress >= bp->b_npages,
3824 ("biodone_finish: paging in progress(%d) < b_npages(%d)",
3825 obj->paging_in_progress, bp->b_npages));
3828 KASSERT(vp->v_holdcnt > 0,
3829 ("biodone_finish: vnode %p has zero hold count", vp));
3830 KASSERT(vp->v_object != NULL,
3831 ("biodone_finish: vnode %p has no vm_object", vp));
3833 foff = bp->b_offset;
3834 KASSERT(bp->b_offset != NOOFFSET,
3835 ("biodone_finish: bp %p has no buffer offset", bp));
3838 * Set B_CACHE if the op was a normal read and no error
3839 * occured. B_CACHE is set for writes in the b*write()
3842 iosize = bp->b_bcount - bp->b_resid;
3843 if (bp->b_iocmd == BIO_READ &&
3844 !(bp->b_flags & (B_INVAL|B_NOCACHE)) &&
3845 !(bp->b_ioflags & BIO_ERROR)) {
3846 bp->b_flags |= B_CACHE;
3849 VM_OBJECT_WLOCK(obj);
3850 for (i = 0; i < bp->b_npages; i++) {
3854 resid = ((foff + PAGE_SIZE) & ~(off_t)PAGE_MASK) - foff;
3859 * cleanup bogus pages, restoring the originals
3862 if (m == bogus_page) {
3863 bogus = bogusflag = 1;
3864 m = vm_page_lookup(obj, OFF_TO_IDX(foff));
3866 panic("biodone: page disappeared!");
3869 KASSERT(OFF_TO_IDX(foff) == m->pindex,
3870 ("biodone_finish: foff(%jd)/pindex(%ju) mismatch",
3871 (intmax_t)foff, (uintmax_t)m->pindex));
3874 * In the write case, the valid and clean bits are
3875 * already changed correctly ( see bdwrite() ), so we
3876 * only need to do this here in the read case.
3878 if ((bp->b_iocmd == BIO_READ) && !bogusflag && resid > 0) {
3879 KASSERT((m->dirty & vm_page_bits(foff &
3880 PAGE_MASK, resid)) == 0, ("bufdone_finish:"
3881 " page %p has unexpected dirty bits", m));
3882 vfs_page_set_valid(bp, foff, m);
3886 vm_object_pip_subtract(obj, 1);
3887 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK;
3890 vm_object_pip_wakeupn(obj, 0);
3891 VM_OBJECT_WUNLOCK(obj);
3892 if (bogus && (bp->b_flags & B_UNMAPPED) == 0) {
3893 BUF_CHECK_MAPPED(bp);
3894 pmap_qenter(trunc_page((vm_offset_t)bp->b_data),
3895 bp->b_pages, bp->b_npages);
3900 * For asynchronous completions, release the buffer now. The brelse
3901 * will do a wakeup there if necessary - so no need to do a wakeup
3902 * here in the async case. The sync case always needs to do a wakeup.
3905 if (bp->b_flags & B_ASYNC) {
3906 if ((bp->b_flags & (B_NOCACHE | B_INVAL | B_RELBUF)) || (bp->b_ioflags & BIO_ERROR))
3915 * This routine is called in lieu of iodone in the case of
3916 * incomplete I/O. This keeps the busy status for pages
3920 vfs_unbusy_pages(struct buf *bp)
3926 runningbufwakeup(bp);
3927 if (!(bp->b_flags & B_VMIO))
3930 obj = bp->b_bufobj->bo_object;
3931 VM_OBJECT_WLOCK(obj);
3932 for (i = 0; i < bp->b_npages; i++) {
3934 if (m == bogus_page) {
3935 m = vm_page_lookup(obj, OFF_TO_IDX(bp->b_offset) + i);
3937 panic("vfs_unbusy_pages: page missing\n");
3939 if ((bp->b_flags & B_UNMAPPED) == 0) {
3940 BUF_CHECK_MAPPED(bp);
3941 pmap_qenter(trunc_page((vm_offset_t)bp->b_data),
3942 bp->b_pages, bp->b_npages);
3944 BUF_CHECK_UNMAPPED(bp);
3946 vm_object_pip_subtract(obj, 1);
3949 vm_object_pip_wakeupn(obj, 0);
3950 VM_OBJECT_WUNLOCK(obj);
3954 * vfs_page_set_valid:
3956 * Set the valid bits in a page based on the supplied offset. The
3957 * range is restricted to the buffer's size.
3959 * This routine is typically called after a read completes.
3962 vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, vm_page_t m)
3967 * Compute the end offset, eoff, such that [off, eoff) does not span a
3968 * page boundary and eoff is not greater than the end of the buffer.
3969 * The end of the buffer, in this case, is our file EOF, not the
3970 * allocation size of the buffer.
3972 eoff = (off + PAGE_SIZE) & ~(vm_ooffset_t)PAGE_MASK;
3973 if (eoff > bp->b_offset + bp->b_bcount)
3974 eoff = bp->b_offset + bp->b_bcount;
3977 * Set valid range. This is typically the entire buffer and thus the
3981 vm_page_set_valid_range(m, off & PAGE_MASK, eoff - off);
3985 * vfs_page_set_validclean:
3987 * Set the valid bits and clear the dirty bits in a page based on the
3988 * supplied offset. The range is restricted to the buffer's size.
3991 vfs_page_set_validclean(struct buf *bp, vm_ooffset_t off, vm_page_t m)
3993 vm_ooffset_t soff, eoff;
3996 * Start and end offsets in buffer. eoff - soff may not cross a
3997 * page boundry or cross the end of the buffer. The end of the
3998 * buffer, in this case, is our file EOF, not the allocation size
4002 eoff = (off + PAGE_SIZE) & ~(off_t)PAGE_MASK;
4003 if (eoff > bp->b_offset + bp->b_bcount)
4004 eoff = bp->b_offset + bp->b_bcount;
4007 * Set valid range. This is typically the entire buffer and thus the
4011 vm_page_set_validclean(
4013 (vm_offset_t) (soff & PAGE_MASK),
4014 (vm_offset_t) (eoff - soff)
4020 * Ensure that all buffer pages are not exclusive busied. If any page is
4021 * exclusive busy, drain it.
4024 vfs_drain_busy_pages(struct buf *bp)
4029 VM_OBJECT_ASSERT_WLOCKED(bp->b_bufobj->bo_object);
4031 for (i = 0; i < bp->b_npages; i++) {
4033 if (vm_page_xbusied(m)) {
4034 for (; last_busied < i; last_busied++)
4035 vm_page_sbusy(bp->b_pages[last_busied]);
4036 while (vm_page_xbusied(m)) {
4038 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object);
4039 vm_page_busy_sleep(m, "vbpage");
4040 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object);
4044 for (i = 0; i < last_busied; i++)
4045 vm_page_sunbusy(bp->b_pages[i]);
4049 * This routine is called before a device strategy routine.
4050 * It is used to tell the VM system that paging I/O is in
4051 * progress, and treat the pages associated with the buffer
4052 * almost as being exclusive busy. Also the object paging_in_progress
4053 * flag is handled to make sure that the object doesn't become
4056 * Since I/O has not been initiated yet, certain buffer flags
4057 * such as BIO_ERROR or B_INVAL may be in an inconsistant state
4058 * and should be ignored.
4061 vfs_busy_pages(struct buf *bp, int clear_modify)
4068 if (!(bp->b_flags & B_VMIO))
4071 obj = bp->b_bufobj->bo_object;
4072 foff = bp->b_offset;
4073 KASSERT(bp->b_offset != NOOFFSET,
4074 ("vfs_busy_pages: no buffer offset"));
4075 VM_OBJECT_WLOCK(obj);
4076 vfs_drain_busy_pages(bp);
4077 if (bp->b_bufsize != 0)
4078 vfs_setdirty_locked_object(bp);
4080 for (i = 0; i < bp->b_npages; i++) {
4083 if ((bp->b_flags & B_CLUSTER) == 0) {
4084 vm_object_pip_add(obj, 1);
4088 * When readying a buffer for a read ( i.e
4089 * clear_modify == 0 ), it is important to do
4090 * bogus_page replacement for valid pages in
4091 * partially instantiated buffers. Partially
4092 * instantiated buffers can, in turn, occur when
4093 * reconstituting a buffer from its VM backing store
4094 * base. We only have to do this if B_CACHE is
4095 * clear ( which causes the I/O to occur in the
4096 * first place ). The replacement prevents the read
4097 * I/O from overwriting potentially dirty VM-backed
4098 * pages. XXX bogus page replacement is, uh, bogus.
4099 * It may not work properly with small-block devices.
4100 * We need to find a better way.
4103 pmap_remove_write(m);
4104 vfs_page_set_validclean(bp, foff, m);
4105 } else if (m->valid == VM_PAGE_BITS_ALL &&
4106 (bp->b_flags & B_CACHE) == 0) {
4107 bp->b_pages[i] = bogus_page;
4110 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK;
4112 VM_OBJECT_WUNLOCK(obj);
4113 if (bogus && (bp->b_flags & B_UNMAPPED) == 0) {
4114 BUF_CHECK_MAPPED(bp);
4115 pmap_qenter(trunc_page((vm_offset_t)bp->b_data),
4116 bp->b_pages, bp->b_npages);
4121 * vfs_bio_set_valid:
4123 * Set the range within the buffer to valid. The range is
4124 * relative to the beginning of the buffer, b_offset. Note that
4125 * b_offset itself may be offset from the beginning of the first
4129 vfs_bio_set_valid(struct buf *bp, int base, int size)
4134 if (!(bp->b_flags & B_VMIO))
4138 * Fixup base to be relative to beginning of first page.
4139 * Set initial n to be the maximum number of bytes in the
4140 * first page that can be validated.
4142 base += (bp->b_offset & PAGE_MASK);
4143 n = PAGE_SIZE - (base & PAGE_MASK);
4145 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object);
4146 for (i = base / PAGE_SIZE; size > 0 && i < bp->b_npages; ++i) {
4150 vm_page_set_valid_range(m, base & PAGE_MASK, n);
4155 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object);
4161 * If the specified buffer is a non-VMIO buffer, clear the entire
4162 * buffer. If the specified buffer is a VMIO buffer, clear and
4163 * validate only the previously invalid portions of the buffer.
4164 * This routine essentially fakes an I/O, so we need to clear
4165 * BIO_ERROR and B_INVAL.
4167 * Note that while we only theoretically need to clear through b_bcount,
4168 * we go ahead and clear through b_bufsize.
4171 vfs_bio_clrbuf(struct buf *bp)
4173 int i, j, mask, sa, ea, slide;
4175 if ((bp->b_flags & (B_VMIO | B_MALLOC)) != B_VMIO) {
4179 bp->b_flags &= ~B_INVAL;
4180 bp->b_ioflags &= ~BIO_ERROR;
4181 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object);
4182 if ((bp->b_npages == 1) && (bp->b_bufsize < PAGE_SIZE) &&
4183 (bp->b_offset & PAGE_MASK) == 0) {
4184 if (bp->b_pages[0] == bogus_page)
4186 mask = (1 << (bp->b_bufsize / DEV_BSIZE)) - 1;
4187 VM_OBJECT_ASSERT_WLOCKED(bp->b_pages[0]->object);
4188 if ((bp->b_pages[0]->valid & mask) == mask)
4190 if ((bp->b_pages[0]->valid & mask) == 0) {
4191 pmap_zero_page_area(bp->b_pages[0], 0, bp->b_bufsize);
4192 bp->b_pages[0]->valid |= mask;
4196 sa = bp->b_offset & PAGE_MASK;
4198 for (i = 0; i < bp->b_npages; i++, sa = 0) {
4199 slide = imin(slide + PAGE_SIZE, bp->b_offset + bp->b_bufsize);
4200 ea = slide & PAGE_MASK;
4203 if (bp->b_pages[i] == bogus_page)
4206 mask = ((1 << ((ea - sa) / DEV_BSIZE)) - 1) << j;
4207 VM_OBJECT_ASSERT_WLOCKED(bp->b_pages[i]->object);
4208 if ((bp->b_pages[i]->valid & mask) == mask)
4210 if ((bp->b_pages[i]->valid & mask) == 0)
4211 pmap_zero_page_area(bp->b_pages[i], sa, ea - sa);
4213 for (; sa < ea; sa += DEV_BSIZE, j++) {
4214 if ((bp->b_pages[i]->valid & (1 << j)) == 0) {
4215 pmap_zero_page_area(bp->b_pages[i],
4220 bp->b_pages[i]->valid |= mask;
4223 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object);
4228 vfs_bio_bzero_buf(struct buf *bp, int base, int size)
4233 if ((bp->b_flags & B_UNMAPPED) == 0) {
4234 BUF_CHECK_MAPPED(bp);
4235 bzero(bp->b_data + base, size);
4237 BUF_CHECK_UNMAPPED(bp);
4238 n = PAGE_SIZE - (base & PAGE_MASK);
4239 for (i = base / PAGE_SIZE; size > 0 && i < bp->b_npages; ++i) {
4243 pmap_zero_page_area(m, base & PAGE_MASK, n);
4252 * vm_hold_load_pages and vm_hold_free_pages get pages into
4253 * a buffers address space. The pages are anonymous and are
4254 * not associated with a file object.
4257 vm_hold_load_pages(struct buf *bp, vm_offset_t from, vm_offset_t to)
4263 BUF_CHECK_MAPPED(bp);
4265 to = round_page(to);
4266 from = round_page(from);
4267 index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT;
4269 for (pg = from; pg < to; pg += PAGE_SIZE, index++) {
4272 * note: must allocate system pages since blocking here
4273 * could interfere with paging I/O, no matter which
4276 p = vm_page_alloc(NULL, 0, VM_ALLOC_SYSTEM | VM_ALLOC_NOOBJ |
4277 VM_ALLOC_WIRED | VM_ALLOC_COUNT((to - pg) >> PAGE_SHIFT));
4282 pmap_qenter(pg, &p, 1);
4283 bp->b_pages[index] = p;
4285 bp->b_npages = index;
4288 /* Return pages associated with this buf to the vm system */
4290 vm_hold_free_pages(struct buf *bp, int newbsize)
4294 int index, newnpages;
4296 BUF_CHECK_MAPPED(bp);
4298 from = round_page((vm_offset_t)bp->b_data + newbsize);
4299 newnpages = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT;
4300 if (bp->b_npages > newnpages)
4301 pmap_qremove(from, bp->b_npages - newnpages);
4302 for (index = newnpages; index < bp->b_npages; index++) {
4303 p = bp->b_pages[index];
4304 bp->b_pages[index] = NULL;
4305 if (vm_page_sbusied(p))
4306 printf("vm_hold_free_pages: blkno: %jd, lblkno: %jd\n",
4307 (intmax_t)bp->b_blkno, (intmax_t)bp->b_lblkno);
4310 atomic_subtract_int(&vm_cnt.v_wire_count, 1);
4312 bp->b_npages = newnpages;
4316 * Map an IO request into kernel virtual address space.
4318 * All requests are (re)mapped into kernel VA space.
4319 * Notice that we use b_bufsize for the size of the buffer
4320 * to be mapped. b_bcount might be modified by the driver.
4322 * Note that even if the caller determines that the address space should
4323 * be valid, a race or a smaller-file mapped into a larger space may
4324 * actually cause vmapbuf() to fail, so all callers of vmapbuf() MUST
4325 * check the return value.
4328 vmapbuf(struct buf *bp, int mapbuf)
4334 if (bp->b_bufsize < 0)
4336 prot = VM_PROT_READ;
4337 if (bp->b_iocmd == BIO_READ)
4338 prot |= VM_PROT_WRITE; /* Less backwards than it looks */
4339 if ((pidx = vm_fault_quick_hold_pages(&curproc->p_vmspace->vm_map,
4340 (vm_offset_t)bp->b_data, bp->b_bufsize, prot, bp->b_pages,
4341 btoc(MAXPHYS))) < 0)
4343 bp->b_npages = pidx;
4344 if (mapbuf || !unmapped_buf_allowed) {
4345 pmap_qenter((vm_offset_t)bp->b_saveaddr, bp->b_pages, pidx);
4346 kva = bp->b_saveaddr;
4347 bp->b_saveaddr = bp->b_data;
4348 bp->b_data = kva + (((vm_offset_t)bp->b_data) & PAGE_MASK);
4349 bp->b_flags &= ~B_UNMAPPED;
4351 bp->b_flags |= B_UNMAPPED;
4352 bp->b_offset = ((vm_offset_t)bp->b_data) & PAGE_MASK;
4353 bp->b_saveaddr = bp->b_data;
4354 bp->b_data = unmapped_buf;
4360 * Free the io map PTEs associated with this IO operation.
4361 * We also invalidate the TLB entries and restore the original b_addr.
4364 vunmapbuf(struct buf *bp)
4368 npages = bp->b_npages;
4369 if (bp->b_flags & B_UNMAPPED)
4370 bp->b_flags &= ~B_UNMAPPED;
4372 pmap_qremove(trunc_page((vm_offset_t)bp->b_data), npages);
4373 vm_page_unhold_pages(bp->b_pages, npages);
4375 bp->b_data = bp->b_saveaddr;
4379 bdone(struct buf *bp)
4383 mtxp = mtx_pool_find(mtxpool_sleep, bp);
4385 bp->b_flags |= B_DONE;
4391 bwait(struct buf *bp, u_char pri, const char *wchan)
4395 mtxp = mtx_pool_find(mtxpool_sleep, bp);
4397 while ((bp->b_flags & B_DONE) == 0)
4398 msleep(bp, mtxp, pri, wchan, 0);
4403 bufsync(struct bufobj *bo, int waitfor)
4406 return (VOP_FSYNC(bo->__bo_vnode, waitfor, curthread));
4410 bufstrategy(struct bufobj *bo, struct buf *bp)
4416 KASSERT(vp == bo->bo_private, ("Inconsistent vnode bufstrategy"));
4417 KASSERT(vp->v_type != VCHR && vp->v_type != VBLK,
4418 ("Wrong vnode in bufstrategy(bp=%p, vp=%p)", bp, vp));
4419 i = VOP_STRATEGY(vp, bp);
4420 KASSERT(i == 0, ("VOP_STRATEGY failed bp=%p vp=%p", bp, bp->b_vp));
4424 bufobj_wrefl(struct bufobj *bo)
4427 KASSERT(bo != NULL, ("NULL bo in bufobj_wref"));
4428 ASSERT_BO_WLOCKED(bo);
4433 bufobj_wref(struct bufobj *bo)
4436 KASSERT(bo != NULL, ("NULL bo in bufobj_wref"));
4443 bufobj_wdrop(struct bufobj *bo)
4446 KASSERT(bo != NULL, ("NULL bo in bufobj_wdrop"));
4448 KASSERT(bo->bo_numoutput > 0, ("bufobj_wdrop non-positive count"));
4449 if ((--bo->bo_numoutput == 0) && (bo->bo_flag & BO_WWAIT)) {
4450 bo->bo_flag &= ~BO_WWAIT;
4451 wakeup(&bo->bo_numoutput);
4457 bufobj_wwait(struct bufobj *bo, int slpflag, int timeo)
4461 KASSERT(bo != NULL, ("NULL bo in bufobj_wwait"));
4462 ASSERT_BO_WLOCKED(bo);
4464 while (bo->bo_numoutput) {
4465 bo->bo_flag |= BO_WWAIT;
4466 error = msleep(&bo->bo_numoutput, BO_LOCKPTR(bo),
4467 slpflag | (PRIBIO + 1), "bo_wwait", timeo);
4475 bpin(struct buf *bp)
4479 mtxp = mtx_pool_find(mtxpool_sleep, bp);
4486 bunpin(struct buf *bp)
4490 mtxp = mtx_pool_find(mtxpool_sleep, bp);
4492 if (--bp->b_pin_count == 0)
4498 bunpin_wait(struct buf *bp)
4502 mtxp = mtx_pool_find(mtxpool_sleep, bp);
4504 while (bp->b_pin_count > 0)
4505 msleep(bp, mtxp, PRIBIO, "bwunpin", 0);
4510 * Set bio_data or bio_ma for struct bio from the struct buf.
4513 bdata2bio(struct buf *bp, struct bio *bip)
4516 if ((bp->b_flags & B_UNMAPPED) != 0) {
4517 KASSERT(unmapped_buf_allowed, ("unmapped"));
4518 bip->bio_ma = bp->b_pages;
4519 bip->bio_ma_n = bp->b_npages;
4520 bip->bio_data = unmapped_buf;
4521 bip->bio_ma_offset = (vm_offset_t)bp->b_offset & PAGE_MASK;
4522 bip->bio_flags |= BIO_UNMAPPED;
4523 KASSERT(round_page(bip->bio_ma_offset + bip->bio_length) /
4524 PAGE_SIZE == bp->b_npages,
4525 ("Buffer %p too short: %d %lld %d", bp, bip->bio_ma_offset,
4526 (long long)bip->bio_length, bip->bio_ma_n));
4528 bip->bio_data = bp->b_data;
4533 #include "opt_ddb.h"
4535 #include <ddb/ddb.h>
4537 /* DDB command to show buffer data */
4538 DB_SHOW_COMMAND(buffer, db_show_buffer)
4541 struct buf *bp = (struct buf *)addr;
4544 db_printf("usage: show buffer <addr>\n");
4548 db_printf("buf at %p\n", bp);
4549 db_printf("b_flags = 0x%b, b_xflags=0x%b, b_vflags=0x%b\n",
4550 (u_int)bp->b_flags, PRINT_BUF_FLAGS, (u_int)bp->b_xflags,
4551 PRINT_BUF_XFLAGS, (u_int)bp->b_vflags, PRINT_BUF_VFLAGS);
4553 "b_error = %d, b_bufsize = %ld, b_bcount = %ld, b_resid = %ld\n"
4554 "b_bufobj = (%p), b_data = %p, b_blkno = %jd, b_lblkno = %jd, "
4556 bp->b_error, bp->b_bufsize, bp->b_bcount, bp->b_resid,
4557 bp->b_bufobj, bp->b_data, (intmax_t)bp->b_blkno,
4558 (intmax_t)bp->b_lblkno, bp->b_dep.lh_first);
4561 db_printf("b_npages = %d, pages(OBJ, IDX, PA): ", bp->b_npages);
4562 for (i = 0; i < bp->b_npages; i++) {
4565 db_printf("(%p, 0x%lx, 0x%lx)", (void *)m->object,
4566 (u_long)m->pindex, (u_long)VM_PAGE_TO_PHYS(m));
4567 if ((i + 1) < bp->b_npages)
4573 BUF_LOCKPRINTINFO(bp);
4576 DB_SHOW_COMMAND(lockedbufs, lockedbufs)
4581 for (i = 0; i < nbuf; i++) {
4583 if (BUF_ISLOCKED(bp)) {
4584 db_show_buffer((uintptr_t)bp, 1, 0, NULL);
4590 DB_SHOW_COMMAND(vnodebufs, db_show_vnodebufs)
4596 db_printf("usage: show vnodebufs <addr>\n");
4599 vp = (struct vnode *)addr;
4600 db_printf("Clean buffers:\n");
4601 TAILQ_FOREACH(bp, &vp->v_bufobj.bo_clean.bv_hd, b_bobufs) {
4602 db_show_buffer((uintptr_t)bp, 1, 0, NULL);
4605 db_printf("Dirty buffers:\n");
4606 TAILQ_FOREACH(bp, &vp->v_bufobj.bo_dirty.bv_hd, b_bobufs) {
4607 db_show_buffer((uintptr_t)bp, 1, 0, NULL);
4612 DB_COMMAND(countfreebufs, db_coundfreebufs)
4615 int i, used = 0, nfree = 0;
4618 db_printf("usage: countfreebufs\n");
4622 for (i = 0; i < nbuf; i++) {
4624 if ((bp->b_flags & B_INFREECNT) != 0)
4630 db_printf("Counted %d free, %d used (%d tot)\n", nfree, used,
4632 db_printf("numfreebuffers is %d\n", numfreebuffers);