2 * Copyright (c) 2004 Poul-Henning Kamp
3 * Copyright (c) 1994,1997 John S. Dyson
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
9 * 1. Redistributions of source code must retain the above copyright
10 * notice, this list of conditions and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 * notice, this list of conditions and the following disclaimer in the
13 * documentation and/or other materials provided with the distribution.
15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
16 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
17 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
18 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
19 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
20 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
21 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
22 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
23 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
24 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29 * this file contains a new buffer I/O scheme implementing a coherent
30 * VM object and buffer cache scheme. Pains have been taken to make
31 * sure that the performance degradation associated with schemes such
32 * as this is not realized.
34 * Author: John S. Dyson
35 * Significant help during the development and debugging phases
36 * had been provided by David Greenman, also of the FreeBSD core team.
38 * see man buf(9) for more info.
41 #include <sys/cdefs.h>
42 __FBSDID("$FreeBSD$");
44 #include <sys/param.h>
45 #include <sys/systm.h>
49 #include <sys/devicestat.h>
50 #include <sys/eventhandler.h>
52 #include <sys/malloc.h>
53 #include <sys/mount.h>
54 #include <sys/mutex.h>
55 #include <sys/kernel.h>
56 #include <sys/kthread.h>
58 #include <sys/resourcevar.h>
59 #include <sys/sysctl.h>
60 #include <sys/vmmeter.h>
61 #include <sys/vnode.h>
62 #include <geom/geom.h>
64 #include <vm/vm_param.h>
65 #include <vm/vm_kern.h>
66 #include <vm/vm_pageout.h>
67 #include <vm/vm_page.h>
68 #include <vm/vm_object.h>
69 #include <vm/vm_extern.h>
70 #include <vm/vm_map.h>
71 #include "opt_directio.h"
74 static MALLOC_DEFINE(M_BIOBUF, "BIO buffer", "BIO buffer");
76 struct bio_ops bioops; /* I/O operation notification */
78 struct buf_ops buf_ops_bio = {
79 .bop_name = "buf_ops_bio",
80 .bop_write = bufwrite,
81 .bop_strategy = bufstrategy,
86 * XXX buf is global because kern_shutdown.c and ffs_checkoverlap has
87 * carnal knowledge of buffers. This knowledge should be moved to vfs_bio.c.
89 struct buf *buf; /* buffer header pool */
91 static struct proc *bufdaemonproc;
93 static int inmem(struct vnode *vp, daddr_t blkno);
94 static void vm_hold_free_pages(struct buf *bp, vm_offset_t from,
96 static void vm_hold_load_pages(struct buf *bp, vm_offset_t from,
98 static void vfs_page_set_valid(struct buf *bp, vm_ooffset_t off,
99 int pageno, vm_page_t m);
100 static void vfs_clean_pages(struct buf *bp);
101 static void vfs_setdirty(struct buf *bp);
102 static void vfs_vmio_release(struct buf *bp);
103 static int vfs_bio_clcheck(struct vnode *vp, int size,
104 daddr_t lblkno, daddr_t blkno);
105 static int flushbufqueues(int flushdeps);
106 static void buf_daemon(void);
107 static void bremfreel(struct buf *bp);
109 int vmiodirenable = TRUE;
110 SYSCTL_INT(_vfs, OID_AUTO, vmiodirenable, CTLFLAG_RW, &vmiodirenable, 0,
111 "Use the VM system for directory writes");
113 SYSCTL_INT(_vfs, OID_AUTO, runningbufspace, CTLFLAG_RD, &runningbufspace, 0,
114 "Amount of presently outstanding async buffer io");
116 SYSCTL_INT(_vfs, OID_AUTO, bufspace, CTLFLAG_RD, &bufspace, 0,
117 "KVA memory used for bufs");
118 static int maxbufspace;
119 SYSCTL_INT(_vfs, OID_AUTO, maxbufspace, CTLFLAG_RD, &maxbufspace, 0,
120 "Maximum allowed value of bufspace (including buf_daemon)");
121 static int bufmallocspace;
122 SYSCTL_INT(_vfs, OID_AUTO, bufmallocspace, CTLFLAG_RD, &bufmallocspace, 0,
123 "Amount of malloced memory for buffers");
124 static int maxbufmallocspace;
125 SYSCTL_INT(_vfs, OID_AUTO, maxmallocbufspace, CTLFLAG_RW, &maxbufmallocspace, 0,
126 "Maximum amount of malloced memory for buffers");
127 static int lobufspace;
128 SYSCTL_INT(_vfs, OID_AUTO, lobufspace, CTLFLAG_RD, &lobufspace, 0,
129 "Minimum amount of buffers we want to have");
131 SYSCTL_INT(_vfs, OID_AUTO, hibufspace, CTLFLAG_RD, &hibufspace, 0,
132 "Maximum allowed value of bufspace (excluding buf_daemon)");
133 static int bufreusecnt;
134 SYSCTL_INT(_vfs, OID_AUTO, bufreusecnt, CTLFLAG_RW, &bufreusecnt, 0,
135 "Number of times we have reused a buffer");
136 static int buffreekvacnt;
137 SYSCTL_INT(_vfs, OID_AUTO, buffreekvacnt, CTLFLAG_RW, &buffreekvacnt, 0,
138 "Number of times we have freed the KVA space from some buffer");
139 static int bufdefragcnt;
140 SYSCTL_INT(_vfs, OID_AUTO, bufdefragcnt, CTLFLAG_RW, &bufdefragcnt, 0,
141 "Number of times we have had to repeat buffer allocation to defragment");
142 static int lorunningspace;
143 SYSCTL_INT(_vfs, OID_AUTO, lorunningspace, CTLFLAG_RW, &lorunningspace, 0,
144 "Minimum preferred space used for in-progress I/O");
145 static int hirunningspace;
146 SYSCTL_INT(_vfs, OID_AUTO, hirunningspace, CTLFLAG_RW, &hirunningspace, 0,
147 "Maximum amount of space to use for in-progress I/O");
148 static int dirtybufferflushes;
149 SYSCTL_INT(_vfs, OID_AUTO, dirtybufferflushes, CTLFLAG_RW, &dirtybufferflushes,
150 0, "Number of bdwrite to bawrite conversions to limit dirty buffers");
151 static int altbufferflushes;
152 SYSCTL_INT(_vfs, OID_AUTO, altbufferflushes, CTLFLAG_RW, &altbufferflushes,
153 0, "Number of fsync flushes to limit dirty buffers");
154 static int recursiveflushes;
155 SYSCTL_INT(_vfs, OID_AUTO, recursiveflushes, CTLFLAG_RW, &recursiveflushes,
156 0, "Number of flushes skipped due to being recursive");
157 static int numdirtybuffers;
158 SYSCTL_INT(_vfs, OID_AUTO, numdirtybuffers, CTLFLAG_RD, &numdirtybuffers, 0,
159 "Number of buffers that are dirty (has unwritten changes) at the moment");
160 static int lodirtybuffers;
161 SYSCTL_INT(_vfs, OID_AUTO, lodirtybuffers, CTLFLAG_RW, &lodirtybuffers, 0,
162 "How many buffers we want to have free before bufdaemon can sleep");
163 static int hidirtybuffers;
164 SYSCTL_INT(_vfs, OID_AUTO, hidirtybuffers, CTLFLAG_RW, &hidirtybuffers, 0,
165 "When the number of dirty buffers is considered severe");
166 static int dirtybufthresh;
167 SYSCTL_INT(_vfs, OID_AUTO, dirtybufthresh, CTLFLAG_RW, &dirtybufthresh,
168 0, "Number of bdwrite to bawrite conversions to clear dirty buffers");
169 static int numfreebuffers;
170 SYSCTL_INT(_vfs, OID_AUTO, numfreebuffers, CTLFLAG_RD, &numfreebuffers, 0,
171 "Number of free buffers");
172 static int lofreebuffers;
173 SYSCTL_INT(_vfs, OID_AUTO, lofreebuffers, CTLFLAG_RW, &lofreebuffers, 0,
175 static int hifreebuffers;
176 SYSCTL_INT(_vfs, OID_AUTO, hifreebuffers, CTLFLAG_RW, &hifreebuffers, 0,
177 "XXX Complicatedly unused");
178 static int getnewbufcalls;
179 SYSCTL_INT(_vfs, OID_AUTO, getnewbufcalls, CTLFLAG_RW, &getnewbufcalls, 0,
180 "Number of calls to getnewbuf");
181 static int getnewbufrestarts;
182 SYSCTL_INT(_vfs, OID_AUTO, getnewbufrestarts, CTLFLAG_RW, &getnewbufrestarts, 0,
183 "Number of times getnewbuf has had to restart a buffer aquisition");
186 * Wakeup point for bufdaemon, as well as indicator of whether it is already
187 * active. Set to 1 when the bufdaemon is already "on" the queue, 0 when it
190 static int bd_request;
193 * This lock synchronizes access to bd_request.
195 static struct mtx bdlock;
198 * bogus page -- for I/O to/from partially complete buffers
199 * this is a temporary solution to the problem, but it is not
200 * really that bad. it would be better to split the buffer
201 * for input in the case of buffers partially already in memory,
202 * but the code is intricate enough already.
204 vm_page_t bogus_page;
207 * Synchronization (sleep/wakeup) variable for active buffer space requests.
208 * Set when wait starts, cleared prior to wakeup().
209 * Used in runningbufwakeup() and waitrunningbufspace().
211 static int runningbufreq;
214 * This lock protects the runningbufreq and synchronizes runningbufwakeup and
215 * waitrunningbufspace().
217 static struct mtx rbreqlock;
220 * Synchronization (sleep/wakeup) variable for buffer requests.
221 * Can contain the VFS_BIO_NEED flags defined below; setting/clearing is done
223 * Used in numdirtywakeup(), bufspacewakeup(), bufcountwakeup(), bwillwrite(),
224 * getnewbuf(), and getblk().
226 static int needsbuffer;
229 * Lock that protects needsbuffer and the sleeps/wakeups surrounding it.
231 static struct mtx nblock;
234 * Lock that protects against bwait()/bdone()/B_DONE races.
237 static struct mtx bdonelock;
240 * Definitions for the buffer free lists.
242 #define BUFFER_QUEUES 5 /* number of free buffer queues */
244 #define QUEUE_NONE 0 /* on no queue */
245 #define QUEUE_CLEAN 1 /* non-B_DELWRI buffers */
246 #define QUEUE_DIRTY 2 /* B_DELWRI buffers */
247 #define QUEUE_EMPTYKVA 3 /* empty buffer headers w/KVA assignment */
248 #define QUEUE_EMPTY 4 /* empty buffer headers */
250 /* Queues for free buffers with various properties */
251 static TAILQ_HEAD(bqueues, buf) bufqueues[BUFFER_QUEUES] = { { 0 } };
253 /* Lock for the bufqueues */
254 static struct mtx bqlock;
257 * Single global constant for BUF_WMESG, to avoid getting multiple references.
258 * buf_wmesg is referred from macros.
260 const char *buf_wmesg = BUF_WMESG;
262 #define VFS_BIO_NEED_ANY 0x01 /* any freeable buffer */
263 #define VFS_BIO_NEED_DIRTYFLUSH 0x02 /* waiting for dirty buffer flush */
264 #define VFS_BIO_NEED_FREE 0x04 /* wait for free bufs, hi hysteresis */
265 #define VFS_BIO_NEED_BUFSPACE 0x08 /* wait for buf space, lo hysteresis */
268 extern void ffs_rawread_setup(void);
269 #endif /* DIRECTIO */
273 * If someone is blocked due to there being too many dirty buffers,
274 * and numdirtybuffers is now reasonable, wake them up.
278 numdirtywakeup(int level)
281 if (numdirtybuffers <= level) {
283 if (needsbuffer & VFS_BIO_NEED_DIRTYFLUSH) {
284 needsbuffer &= ~VFS_BIO_NEED_DIRTYFLUSH;
285 wakeup(&needsbuffer);
294 * Called when buffer space is potentially available for recovery.
295 * getnewbuf() will block on this flag when it is unable to free
296 * sufficient buffer space. Buffer space becomes recoverable when
297 * bp's get placed back in the queues.
305 * If someone is waiting for BUF space, wake them up. Even
306 * though we haven't freed the kva space yet, the waiting
307 * process will be able to now.
310 if (needsbuffer & VFS_BIO_NEED_BUFSPACE) {
311 needsbuffer &= ~VFS_BIO_NEED_BUFSPACE;
312 wakeup(&needsbuffer);
318 * runningbufwakeup() - in-progress I/O accounting.
322 runningbufwakeup(struct buf *bp)
325 if (bp->b_runningbufspace) {
326 atomic_subtract_int(&runningbufspace, bp->b_runningbufspace);
327 bp->b_runningbufspace = 0;
328 mtx_lock(&rbreqlock);
329 if (runningbufreq && runningbufspace <= lorunningspace) {
331 wakeup(&runningbufreq);
333 mtx_unlock(&rbreqlock);
340 * Called when a buffer has been added to one of the free queues to
341 * account for the buffer and to wakeup anyone waiting for free buffers.
342 * This typically occurs when large amounts of metadata are being handled
343 * by the buffer cache ( else buffer space runs out first, usually ).
350 atomic_add_int(&numfreebuffers, 1);
353 needsbuffer &= ~VFS_BIO_NEED_ANY;
354 if (numfreebuffers >= hifreebuffers)
355 needsbuffer &= ~VFS_BIO_NEED_FREE;
356 wakeup(&needsbuffer);
362 * waitrunningbufspace()
364 * runningbufspace is a measure of the amount of I/O currently
365 * running. This routine is used in async-write situations to
366 * prevent creating huge backups of pending writes to a device.
367 * Only asynchronous writes are governed by this function.
369 * Reads will adjust runningbufspace, but will not block based on it.
370 * The read load has a side effect of reducing the allowed write load.
372 * This does NOT turn an async write into a sync write. It waits
373 * for earlier writes to complete and generally returns before the
374 * caller's write has reached the device.
377 waitrunningbufspace(void)
380 mtx_lock(&rbreqlock);
381 while (runningbufspace > hirunningspace) {
383 msleep(&runningbufreq, &rbreqlock, PVM, "wdrain", 0);
385 mtx_unlock(&rbreqlock);
390 * vfs_buf_test_cache:
392 * Called when a buffer is extended. This function clears the B_CACHE
393 * bit if the newly extended portion of the buffer does not contain
398 vfs_buf_test_cache(struct buf *bp,
399 vm_ooffset_t foff, vm_offset_t off, vm_offset_t size,
403 VM_OBJECT_LOCK_ASSERT(m->object, MA_OWNED);
404 if (bp->b_flags & B_CACHE) {
405 int base = (foff + off) & PAGE_MASK;
406 if (vm_page_is_valid(m, base, size) == 0)
407 bp->b_flags &= ~B_CACHE;
411 /* Wake up the buffer deamon if necessary */
414 bd_wakeup(int dirtybuflevel)
418 if (bd_request == 0 && numdirtybuffers >= dirtybuflevel) {
426 * bd_speedup - speedup the buffer cache flushing code
438 * Calculating buffer cache scaling values and reserve space for buffer
439 * headers. This is called during low level kernel initialization and
440 * may be called more then once. We CANNOT write to the memory area
441 * being reserved at this time.
444 kern_vfs_bio_buffer_alloc(caddr_t v, long physmem_est)
448 * physmem_est is in pages. Convert it to kilobytes (assumes
449 * PAGE_SIZE is >= 1K)
451 physmem_est = physmem_est * (PAGE_SIZE / 1024);
454 * The nominal buffer size (and minimum KVA allocation) is BKVASIZE.
455 * For the first 64MB of ram nominally allocate sufficient buffers to
456 * cover 1/4 of our ram. Beyond the first 64MB allocate additional
457 * buffers to cover 1/20 of our ram over 64MB. When auto-sizing
458 * the buffer cache we limit the eventual kva reservation to
461 * factor represents the 1/4 x ram conversion.
464 int factor = 4 * BKVASIZE / 1024;
467 if (physmem_est > 4096)
468 nbuf += min((physmem_est - 4096) / factor,
470 if (physmem_est > 65536)
471 nbuf += (physmem_est - 65536) * 2 / (factor * 5);
473 if (maxbcache && nbuf > maxbcache / BKVASIZE)
474 nbuf = maxbcache / BKVASIZE;
479 * Do not allow the buffer_map to be more then 1/2 the size of the
482 if (nbuf > (kernel_map->max_offset - kernel_map->min_offset) /
484 nbuf = (kernel_map->max_offset - kernel_map->min_offset) /
486 printf("Warning: nbufs capped at %d\n", nbuf);
491 * swbufs are used as temporary holders for I/O, such as paging I/O.
492 * We have no less then 16 and no more then 256.
494 nswbuf = max(min(nbuf/4, 256), 16);
496 if (nswbuf < NSWBUF_MIN)
504 * Reserve space for the buffer cache buffers
507 v = (caddr_t)(swbuf + nswbuf);
509 v = (caddr_t)(buf + nbuf);
514 /* Initialize the buffer subsystem. Called before use of any buffers. */
521 mtx_init(&bqlock, "buf queue lock", NULL, MTX_DEF);
522 mtx_init(&rbreqlock, "runningbufspace lock", NULL, MTX_DEF);
523 mtx_init(&nblock, "needsbuffer lock", NULL, MTX_DEF);
524 mtx_init(&bdlock, "buffer daemon lock", NULL, MTX_DEF);
525 mtx_init(&bdonelock, "bdone lock", NULL, MTX_DEF);
527 /* next, make a null set of free lists */
528 for (i = 0; i < BUFFER_QUEUES; i++)
529 TAILQ_INIT(&bufqueues[i]);
531 /* finally, initialize each buffer header and stick on empty q */
532 for (i = 0; i < nbuf; i++) {
534 bzero(bp, sizeof *bp);
535 bp->b_flags = B_INVAL; /* we're just an empty header */
536 bp->b_rcred = NOCRED;
537 bp->b_wcred = NOCRED;
538 bp->b_qindex = QUEUE_EMPTY;
541 LIST_INIT(&bp->b_dep);
543 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_EMPTY], bp, b_freelist);
547 * maxbufspace is the absolute maximum amount of buffer space we are
548 * allowed to reserve in KVM and in real terms. The absolute maximum
549 * is nominally used by buf_daemon. hibufspace is the nominal maximum
550 * used by most other processes. The differential is required to
551 * ensure that buf_daemon is able to run when other processes might
552 * be blocked waiting for buffer space.
554 * maxbufspace is based on BKVASIZE. Allocating buffers larger then
555 * this may result in KVM fragmentation which is not handled optimally
558 maxbufspace = nbuf * BKVASIZE;
559 hibufspace = imax(3 * maxbufspace / 4, maxbufspace - MAXBSIZE * 10);
560 lobufspace = hibufspace - MAXBSIZE;
562 lorunningspace = 512 * 1024;
563 hirunningspace = 1024 * 1024;
566 * Limit the amount of malloc memory since it is wired permanently into
567 * the kernel space. Even though this is accounted for in the buffer
568 * allocation, we don't want the malloced region to grow uncontrolled.
569 * The malloc scheme improves memory utilization significantly on average
570 * (small) directories.
572 maxbufmallocspace = hibufspace / 20;
575 * Reduce the chance of a deadlock occuring by limiting the number
576 * of delayed-write dirty buffers we allow to stack up.
578 hidirtybuffers = nbuf / 4 + 20;
579 dirtybufthresh = hidirtybuffers * 9 / 10;
582 * To support extreme low-memory systems, make sure hidirtybuffers cannot
583 * eat up all available buffer space. This occurs when our minimum cannot
584 * be met. We try to size hidirtybuffers to 3/4 our buffer space assuming
585 * BKVASIZE'd (8K) buffers.
587 while (hidirtybuffers * BKVASIZE > 3 * hibufspace / 4) {
588 hidirtybuffers >>= 1;
590 lodirtybuffers = hidirtybuffers / 2;
593 * Try to keep the number of free buffers in the specified range,
594 * and give special processes (e.g. like buf_daemon) access to an
597 lofreebuffers = nbuf / 18 + 5;
598 hifreebuffers = 2 * lofreebuffers;
599 numfreebuffers = nbuf;
602 * Maximum number of async ops initiated per buf_daemon loop. This is
603 * somewhat of a hack at the moment, we really need to limit ourselves
604 * based on the number of bytes of I/O in-transit that were initiated
608 bogus_page = vm_page_alloc(NULL, 0, VM_ALLOC_NOOBJ |
609 VM_ALLOC_NORMAL | VM_ALLOC_WIRED);
613 * bfreekva() - free the kva allocation for a buffer.
615 * Since this call frees up buffer space, we call bufspacewakeup().
618 bfreekva(struct buf *bp)
622 atomic_add_int(&buffreekvacnt, 1);
623 atomic_subtract_int(&bufspace, bp->b_kvasize);
624 vm_map_lock(buffer_map);
625 vm_map_delete(buffer_map,
626 (vm_offset_t) bp->b_kvabase,
627 (vm_offset_t) bp->b_kvabase + bp->b_kvasize
629 vm_map_unlock(buffer_map);
638 * Mark the buffer for removal from the appropriate free list in brelse.
642 bremfree(struct buf *bp)
645 CTR3(KTR_BUF, "bremfree(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
646 KASSERT(BUF_REFCNT(bp), ("bremfree: buf must be locked."));
647 KASSERT((bp->b_flags & B_REMFREE) == 0,
648 ("bremfree: buffer %p already marked for delayed removal.", bp));
649 KASSERT(bp->b_qindex != QUEUE_NONE,
650 ("bremfree: buffer %p not on a queue.", bp));
652 bp->b_flags |= B_REMFREE;
653 /* Fixup numfreebuffers count. */
654 if ((bp->b_flags & B_INVAL) || (bp->b_flags & B_DELWRI) == 0)
655 atomic_subtract_int(&numfreebuffers, 1);
661 * Force an immediate removal from a free list. Used only in nfs when
662 * it abuses the b_freelist pointer.
665 bremfreef(struct buf *bp)
675 * Removes a buffer from the free list, must be called with the
679 bremfreel(struct buf *bp)
681 CTR3(KTR_BUF, "bremfreel(%p) vp %p flags %X",
682 bp, bp->b_vp, bp->b_flags);
683 KASSERT(BUF_REFCNT(bp), ("bremfreel: buffer %p not locked.", bp));
684 KASSERT(bp->b_qindex != QUEUE_NONE,
685 ("bremfreel: buffer %p not on a queue.", bp));
686 mtx_assert(&bqlock, MA_OWNED);
688 TAILQ_REMOVE(&bufqueues[bp->b_qindex], bp, b_freelist);
689 bp->b_qindex = QUEUE_NONE;
691 * If this was a delayed bremfree() we only need to remove the buffer
692 * from the queue and return the stats are already done.
694 if (bp->b_flags & B_REMFREE) {
695 bp->b_flags &= ~B_REMFREE;
699 * Fixup numfreebuffers count. If the buffer is invalid or not
700 * delayed-write, the buffer was free and we must decrement
703 if ((bp->b_flags & B_INVAL) || (bp->b_flags & B_DELWRI) == 0)
704 atomic_subtract_int(&numfreebuffers, 1);
709 * Get a buffer with the specified data. Look in the cache first. We
710 * must clear BIO_ERROR and B_INVAL prior to initiating I/O. If B_CACHE
711 * is set, the buffer is valid and we do not have to do anything ( see
712 * getblk() ). This is really just a special case of breadn().
715 bread(struct vnode * vp, daddr_t blkno, int size, struct ucred * cred,
719 return (breadn(vp, blkno, size, 0, 0, 0, cred, bpp));
723 * Operates like bread, but also starts asynchronous I/O on
724 * read-ahead blocks. We must clear BIO_ERROR and B_INVAL prior
725 * to initiating I/O . If B_CACHE is set, the buffer is valid
726 * and we do not have to do anything.
729 breadn(struct vnode * vp, daddr_t blkno, int size,
730 daddr_t * rablkno, int *rabsize,
731 int cnt, struct ucred * cred, struct buf **bpp)
733 struct buf *bp, *rabp;
735 int rv = 0, readwait = 0;
737 CTR3(KTR_BUF, "breadn(%p, %jd, %d)", vp, blkno, size);
738 *bpp = bp = getblk(vp, blkno, size, 0, 0, 0);
740 /* if not found in cache, do some I/O */
741 if ((bp->b_flags & B_CACHE) == 0) {
742 if (curthread != PCPU_GET(idlethread))
743 curthread->td_proc->p_stats->p_ru.ru_inblock++;
744 bp->b_iocmd = BIO_READ;
745 bp->b_flags &= ~B_INVAL;
746 bp->b_ioflags &= ~BIO_ERROR;
747 if (bp->b_rcred == NOCRED && cred != NOCRED)
748 bp->b_rcred = crhold(cred);
749 vfs_busy_pages(bp, 0);
750 bp->b_iooffset = dbtob(bp->b_blkno);
755 for (i = 0; i < cnt; i++, rablkno++, rabsize++) {
756 if (inmem(vp, *rablkno))
758 rabp = getblk(vp, *rablkno, *rabsize, 0, 0, 0);
760 if ((rabp->b_flags & B_CACHE) == 0) {
761 if (curthread != PCPU_GET(idlethread))
762 curthread->td_proc->p_stats->p_ru.ru_inblock++;
763 rabp->b_flags |= B_ASYNC;
764 rabp->b_flags &= ~B_INVAL;
765 rabp->b_ioflags &= ~BIO_ERROR;
766 rabp->b_iocmd = BIO_READ;
767 if (rabp->b_rcred == NOCRED && cred != NOCRED)
768 rabp->b_rcred = crhold(cred);
769 vfs_busy_pages(rabp, 0);
771 rabp->b_iooffset = dbtob(rabp->b_blkno);
785 * Write, release buffer on completion. (Done by iodone
786 * if async). Do not bother writing anything if the buffer
789 * Note that we set B_CACHE here, indicating that buffer is
790 * fully valid and thus cacheable. This is true even of NFS
791 * now so we set it generally. This could be set either here
792 * or in biodone() since the I/O is synchronous. We put it
796 bufwrite(struct buf *bp)
800 CTR3(KTR_BUF, "bufwrite(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
801 if (bp->b_flags & B_INVAL) {
806 oldflags = bp->b_flags;
808 if (BUF_REFCNT(bp) == 0)
809 panic("bufwrite: buffer is not busy???");
810 KASSERT(!(bp->b_vflags & BV_BKGRDINPROG),
811 ("FFS background buffer should not get here %p", bp));
813 /* Mark the buffer clean */
816 bp->b_flags &= ~B_DONE;
817 bp->b_ioflags &= ~BIO_ERROR;
818 bp->b_flags |= B_CACHE;
819 bp->b_iocmd = BIO_WRITE;
821 bufobj_wref(bp->b_bufobj);
822 vfs_busy_pages(bp, 1);
825 * Normal bwrites pipeline writes
827 bp->b_runningbufspace = bp->b_bufsize;
828 atomic_add_int(&runningbufspace, bp->b_runningbufspace);
830 if (curthread != PCPU_GET(idlethread))
831 curthread->td_proc->p_stats->p_ru.ru_oublock++;
832 if (oldflags & B_ASYNC)
834 bp->b_iooffset = dbtob(bp->b_blkno);
837 if ((oldflags & B_ASYNC) == 0) {
838 int rtval = bufwait(bp);
843 * don't allow the async write to saturate the I/O
844 * system. We will not deadlock here because
845 * we are blocking waiting for I/O that is already in-progress
846 * to complete. We do not block here if it is the update
847 * or syncer daemon trying to clean up as that can lead
850 if (curthread->td_proc != bufdaemonproc &&
851 curthread->td_proc != updateproc)
852 waitrunningbufspace();
859 * Delayed write. (Buffer is marked dirty). Do not bother writing
860 * anything if the buffer is marked invalid.
862 * Note that since the buffer must be completely valid, we can safely
863 * set B_CACHE. In fact, we have to set B_CACHE here rather then in
864 * biodone() in order to prevent getblk from writing the buffer
868 bdwrite(struct buf *bp)
870 struct thread *td = curthread;
875 CTR3(KTR_BUF, "bdwrite(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
876 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp));
877 KASSERT(BUF_REFCNT(bp) != 0, ("bdwrite: buffer is not busy"));
879 if (bp->b_flags & B_INVAL) {
885 * If we have too many dirty buffers, don't create any more.
886 * If we are wildly over our limit, then force a complete
887 * cleanup. Otherwise, just keep the situation from getting
888 * out of control. Note that we have to avoid a recursive
889 * disaster and not try to clean up after our own cleanup!
893 if ((td->td_pflags & TDP_COWINPROGRESS) == 0) {
895 if (bo->bo_dirty.bv_cnt > dirtybufthresh + 10) {
897 (void) VOP_FSYNC(vp, MNT_NOWAIT, td);
899 } else if (bo->bo_dirty.bv_cnt > dirtybufthresh) {
901 * Try to find a buffer to flush.
903 TAILQ_FOREACH(nbp, &bo->bo_dirty.bv_hd, b_bobufs) {
904 if ((nbp->b_vflags & BV_BKGRDINPROG) ||
906 LK_EXCLUSIVE | LK_NOWAIT, NULL))
909 panic("bdwrite: found ourselves");
911 /* Don't countdeps with the bo lock held. */
912 if (buf_countdeps(nbp, 0)) {
917 if (nbp->b_flags & B_CLUSTEROK) {
923 dirtybufferflushes++;
935 * Set B_CACHE, indicating that the buffer is fully valid. This is
936 * true even of NFS now.
938 bp->b_flags |= B_CACHE;
941 * This bmap keeps the system from needing to do the bmap later,
942 * perhaps when the system is attempting to do a sync. Since it
943 * is likely that the indirect block -- or whatever other datastructure
944 * that the filesystem needs is still in memory now, it is a good
945 * thing to do this. Note also, that if the pageout daemon is
946 * requesting a sync -- there might not be enough memory to do
947 * the bmap then... So, this is important to do.
949 if (vp->v_type != VCHR && bp->b_lblkno == bp->b_blkno) {
950 VOP_BMAP(vp, bp->b_lblkno, NULL, &bp->b_blkno, NULL, NULL);
954 * Set the *dirty* buffer range based upon the VM system dirty pages.
959 * We need to do this here to satisfy the vnode_pager and the
960 * pageout daemon, so that it thinks that the pages have been
961 * "cleaned". Note that since the pages are in a delayed write
962 * buffer -- the VFS layer "will" see that the pages get written
963 * out on the next sync, or perhaps the cluster will be completed.
969 * Wakeup the buffer flushing daemon if we have a lot of dirty
970 * buffers (midpoint between our recovery point and our stall
973 bd_wakeup((lodirtybuffers + hidirtybuffers) / 2);
976 * note: we cannot initiate I/O from a bdwrite even if we wanted to,
977 * due to the softdep code.
984 * Turn buffer into delayed write request. We must clear BIO_READ and
985 * B_RELBUF, and we must set B_DELWRI. We reassign the buffer to
986 * itself to properly update it in the dirty/clean lists. We mark it
987 * B_DONE to ensure that any asynchronization of the buffer properly
988 * clears B_DONE ( else a panic will occur later ).
990 * bdirty() is kinda like bdwrite() - we have to clear B_INVAL which
991 * might have been set pre-getblk(). Unlike bwrite/bdwrite, bdirty()
992 * should only be called if the buffer is known-good.
994 * Since the buffer is not on a queue, we do not update the numfreebuffers
997 * The buffer must be on QUEUE_NONE.
1000 bdirty(struct buf *bp)
1003 CTR3(KTR_BUF, "bdirty(%p) vp %p flags %X",
1004 bp, bp->b_vp, bp->b_flags);
1005 KASSERT(BUF_REFCNT(bp) == 1, ("bdirty: bp %p not locked",bp));
1006 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp));
1007 KASSERT(bp->b_flags & B_REMFREE || bp->b_qindex == QUEUE_NONE,
1008 ("bdirty: buffer %p still on queue %d", bp, bp->b_qindex));
1009 bp->b_flags &= ~(B_RELBUF);
1010 bp->b_iocmd = BIO_WRITE;
1012 if ((bp->b_flags & B_DELWRI) == 0) {
1013 bp->b_flags |= /* XXX B_DONE | */ B_DELWRI;
1015 atomic_add_int(&numdirtybuffers, 1);
1016 bd_wakeup((lodirtybuffers + hidirtybuffers) / 2);
1023 * Clear B_DELWRI for buffer.
1025 * Since the buffer is not on a queue, we do not update the numfreebuffers
1028 * The buffer must be on QUEUE_NONE.
1032 bundirty(struct buf *bp)
1035 CTR3(KTR_BUF, "bundirty(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
1036 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp));
1037 KASSERT(bp->b_flags & B_REMFREE || bp->b_qindex == QUEUE_NONE,
1038 ("bundirty: buffer %p still on queue %d", bp, bp->b_qindex));
1039 KASSERT(BUF_REFCNT(bp) == 1, ("bundirty: bp %p not locked",bp));
1041 if (bp->b_flags & B_DELWRI) {
1042 bp->b_flags &= ~B_DELWRI;
1044 atomic_subtract_int(&numdirtybuffers, 1);
1045 numdirtywakeup(lodirtybuffers);
1048 * Since it is now being written, we can clear its deferred write flag.
1050 bp->b_flags &= ~B_DEFERRED;
1056 * Asynchronous write. Start output on a buffer, but do not wait for
1057 * it to complete. The buffer is released when the output completes.
1059 * bwrite() ( or the VOP routine anyway ) is responsible for handling
1060 * B_INVAL buffers. Not us.
1063 bawrite(struct buf *bp)
1066 bp->b_flags |= B_ASYNC;
1073 * Called prior to the locking of any vnodes when we are expecting to
1074 * write. We do not want to starve the buffer cache with too many
1075 * dirty buffers so we block here. By blocking prior to the locking
1076 * of any vnodes we attempt to avoid the situation where a locked vnode
1077 * prevents the various system daemons from flushing related buffers.
1084 if (numdirtybuffers >= hidirtybuffers) {
1086 while (numdirtybuffers >= hidirtybuffers) {
1088 needsbuffer |= VFS_BIO_NEED_DIRTYFLUSH;
1089 msleep(&needsbuffer, &nblock,
1090 (PRIBIO + 4), "flswai", 0);
1092 mtx_unlock(&nblock);
1097 * Return true if we have too many dirty buffers.
1100 buf_dirty_count_severe(void)
1103 return(numdirtybuffers >= hidirtybuffers);
1109 * Release a busy buffer and, if requested, free its resources. The
1110 * buffer will be stashed in the appropriate bufqueue[] allowing it
1111 * to be accessed later as a cache entity or reused for other purposes.
1114 brelse(struct buf *bp)
1116 CTR3(KTR_BUF, "brelse(%p) vp %p flags %X",
1117 bp, bp->b_vp, bp->b_flags);
1118 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)),
1119 ("brelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp));
1121 if (bp->b_iocmd == BIO_WRITE &&
1122 (bp->b_ioflags & BIO_ERROR) &&
1123 !(bp->b_flags & B_INVAL)) {
1125 * Failed write, redirty. Must clear BIO_ERROR to prevent
1126 * pages from being scrapped. If B_INVAL is set then
1127 * this case is not run and the next case is run to
1128 * destroy the buffer. B_INVAL can occur if the buffer
1129 * is outside the range supported by the underlying device.
1131 bp->b_ioflags &= ~BIO_ERROR;
1133 } else if ((bp->b_flags & (B_NOCACHE | B_INVAL)) ||
1134 (bp->b_ioflags & BIO_ERROR) || (bp->b_bufsize <= 0)) {
1136 * Either a failed I/O or we were asked to free or not
1139 bp->b_flags |= B_INVAL;
1140 if (LIST_FIRST(&bp->b_dep) != NULL)
1142 if (bp->b_flags & B_DELWRI) {
1143 atomic_subtract_int(&numdirtybuffers, 1);
1144 numdirtywakeup(lodirtybuffers);
1146 bp->b_flags &= ~(B_DELWRI | B_CACHE);
1147 if ((bp->b_flags & B_VMIO) == 0) {
1156 * We must clear B_RELBUF if B_DELWRI is set. If vfs_vmio_release()
1157 * is called with B_DELWRI set, the underlying pages may wind up
1158 * getting freed causing a previous write (bdwrite()) to get 'lost'
1159 * because pages associated with a B_DELWRI bp are marked clean.
1161 * We still allow the B_INVAL case to call vfs_vmio_release(), even
1162 * if B_DELWRI is set.
1164 * If B_DELWRI is not set we may have to set B_RELBUF if we are low
1165 * on pages to return pages to the VM page queues.
1167 if (bp->b_flags & B_DELWRI)
1168 bp->b_flags &= ~B_RELBUF;
1169 else if (vm_page_count_severe()) {
1171 * XXX This lock may not be necessary since BKGRDINPROG
1172 * cannot be set while we hold the buf lock, it can only be
1173 * cleared if it is already pending.
1176 BO_LOCK(bp->b_bufobj);
1177 if (!(bp->b_vflags & BV_BKGRDINPROG))
1178 bp->b_flags |= B_RELBUF;
1179 BO_UNLOCK(bp->b_bufobj);
1181 bp->b_flags |= B_RELBUF;
1185 * VMIO buffer rundown. It is not very necessary to keep a VMIO buffer
1186 * constituted, not even NFS buffers now. Two flags effect this. If
1187 * B_INVAL, the struct buf is invalidated but the VM object is kept
1188 * around ( i.e. so it is trivial to reconstitute the buffer later ).
1190 * If BIO_ERROR or B_NOCACHE is set, pages in the VM object will be
1191 * invalidated. BIO_ERROR cannot be set for a failed write unless the
1192 * buffer is also B_INVAL because it hits the re-dirtying code above.
1194 * Normally we can do this whether a buffer is B_DELWRI or not. If
1195 * the buffer is an NFS buffer, it is tracking piecemeal writes or
1196 * the commit state and we cannot afford to lose the buffer. If the
1197 * buffer has a background write in progress, we need to keep it
1198 * around to prevent it from being reconstituted and starting a second
1201 if ((bp->b_flags & B_VMIO)
1202 && !(bp->b_vp->v_mount != NULL &&
1203 (bp->b_vp->v_mount->mnt_vfc->vfc_flags & VFCF_NETWORK) != 0 &&
1204 !vn_isdisk(bp->b_vp, NULL) &&
1205 (bp->b_flags & B_DELWRI))
1214 obj = bp->b_bufobj->bo_object;
1217 * Get the base offset and length of the buffer. Note that
1218 * in the VMIO case if the buffer block size is not
1219 * page-aligned then b_data pointer may not be page-aligned.
1220 * But our b_pages[] array *IS* page aligned.
1222 * block sizes less then DEV_BSIZE (usually 512) are not
1223 * supported due to the page granularity bits (m->valid,
1224 * m->dirty, etc...).
1226 * See man buf(9) for more information
1228 resid = bp->b_bufsize;
1229 foff = bp->b_offset;
1230 VM_OBJECT_LOCK(obj);
1231 for (i = 0; i < bp->b_npages; i++) {
1237 * If we hit a bogus page, fixup *all* the bogus pages
1240 if (m == bogus_page) {
1241 poff = OFF_TO_IDX(bp->b_offset);
1244 for (j = i; j < bp->b_npages; j++) {
1246 mtmp = bp->b_pages[j];
1247 if (mtmp == bogus_page) {
1248 mtmp = vm_page_lookup(obj, poff + j);
1250 panic("brelse: page missing\n");
1252 bp->b_pages[j] = mtmp;
1256 if ((bp->b_flags & B_INVAL) == 0) {
1258 trunc_page((vm_offset_t)bp->b_data),
1259 bp->b_pages, bp->b_npages);
1263 if ((bp->b_flags & B_NOCACHE) ||
1264 (bp->b_ioflags & BIO_ERROR)) {
1265 int poffset = foff & PAGE_MASK;
1266 int presid = resid > (PAGE_SIZE - poffset) ?
1267 (PAGE_SIZE - poffset) : resid;
1269 KASSERT(presid >= 0, ("brelse: extra page"));
1270 vm_page_lock_queues();
1271 vm_page_set_invalid(m, poffset, presid);
1272 vm_page_unlock_queues();
1274 printf("avoided corruption bug in bogus_page/brelse code\n");
1276 resid -= PAGE_SIZE - (foff & PAGE_MASK);
1277 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK;
1279 VM_OBJECT_UNLOCK(obj);
1280 if (bp->b_flags & (B_INVAL | B_RELBUF))
1281 vfs_vmio_release(bp);
1283 } else if (bp->b_flags & B_VMIO) {
1285 if (bp->b_flags & (B_INVAL | B_RELBUF)) {
1286 vfs_vmio_release(bp);
1291 if (BUF_REFCNT(bp) > 1) {
1292 /* do not release to free list */
1299 /* Handle delayed bremfree() processing. */
1300 if (bp->b_flags & B_REMFREE)
1302 if (bp->b_qindex != QUEUE_NONE)
1303 panic("brelse: free buffer onto another queue???");
1305 /* buffers with no memory */
1306 if (bp->b_bufsize == 0) {
1307 bp->b_flags |= B_INVAL;
1308 bp->b_xflags &= ~(BX_BKGRDWRITE | BX_ALTDATA);
1309 if (bp->b_vflags & BV_BKGRDINPROG)
1310 panic("losing buffer 1");
1311 if (bp->b_kvasize) {
1312 bp->b_qindex = QUEUE_EMPTYKVA;
1314 bp->b_qindex = QUEUE_EMPTY;
1316 TAILQ_INSERT_HEAD(&bufqueues[bp->b_qindex], bp, b_freelist);
1317 /* buffers with junk contents */
1318 } else if (bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF) ||
1319 (bp->b_ioflags & BIO_ERROR)) {
1320 bp->b_flags |= B_INVAL;
1321 bp->b_xflags &= ~(BX_BKGRDWRITE | BX_ALTDATA);
1322 if (bp->b_vflags & BV_BKGRDINPROG)
1323 panic("losing buffer 2");
1324 bp->b_qindex = QUEUE_CLEAN;
1325 TAILQ_INSERT_HEAD(&bufqueues[QUEUE_CLEAN], bp, b_freelist);
1326 /* remaining buffers */
1328 if (bp->b_flags & B_DELWRI)
1329 bp->b_qindex = QUEUE_DIRTY;
1331 bp->b_qindex = QUEUE_CLEAN;
1332 if (bp->b_flags & B_AGE)
1333 TAILQ_INSERT_HEAD(&bufqueues[bp->b_qindex], bp, b_freelist);
1335 TAILQ_INSERT_TAIL(&bufqueues[bp->b_qindex], bp, b_freelist);
1337 mtx_unlock(&bqlock);
1340 * If B_INVAL and B_DELWRI is set, clear B_DELWRI. We have already
1341 * placed the buffer on the correct queue. We must also disassociate
1342 * the device and vnode for a B_INVAL buffer so gbincore() doesn't
1345 if (bp->b_flags & B_INVAL) {
1346 if (bp->b_flags & B_DELWRI)
1353 * Fixup numfreebuffers count. The bp is on an appropriate queue
1354 * unless locked. We then bump numfreebuffers if it is not B_DELWRI.
1355 * We've already handled the B_INVAL case ( B_DELWRI will be clear
1356 * if B_INVAL is set ).
1359 if (!(bp->b_flags & B_DELWRI))
1363 * Something we can maybe free or reuse
1365 if (bp->b_bufsize || bp->b_kvasize)
1368 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF | B_DIRECT);
1369 if ((bp->b_flags & B_DELWRI) == 0 && (bp->b_xflags & BX_VNDIRTY))
1370 panic("brelse: not dirty");
1376 * Release a buffer back to the appropriate queue but do not try to free
1377 * it. The buffer is expected to be used again soon.
1379 * bqrelse() is used by bdwrite() to requeue a delayed write, and used by
1380 * biodone() to requeue an async I/O on completion. It is also used when
1381 * known good buffers need to be requeued but we think we may need the data
1384 * XXX we should be able to leave the B_RELBUF hint set on completion.
1387 bqrelse(struct buf *bp)
1389 CTR3(KTR_BUF, "bqrelse(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
1390 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)),
1391 ("bqrelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp));
1393 if (BUF_REFCNT(bp) > 1) {
1394 /* do not release to free list */
1399 /* Handle delayed bremfree() processing. */
1400 if (bp->b_flags & B_REMFREE)
1402 if (bp->b_qindex != QUEUE_NONE)
1403 panic("bqrelse: free buffer onto another queue???");
1404 /* buffers with stale but valid contents */
1405 if (bp->b_flags & B_DELWRI) {
1406 bp->b_qindex = QUEUE_DIRTY;
1407 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_DIRTY], bp, b_freelist);
1410 * XXX This lock may not be necessary since BKGRDINPROG
1411 * cannot be set while we hold the buf lock, it can only be
1412 * cleared if it is already pending.
1414 BO_LOCK(bp->b_bufobj);
1415 if (!vm_page_count_severe() || bp->b_vflags & BV_BKGRDINPROG) {
1416 BO_UNLOCK(bp->b_bufobj);
1417 bp->b_qindex = QUEUE_CLEAN;
1418 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_CLEAN], bp,
1422 * We are too low on memory, we have to try to free
1423 * the buffer (most importantly: the wired pages
1424 * making up its backing store) *now*.
1426 BO_UNLOCK(bp->b_bufobj);
1427 mtx_unlock(&bqlock);
1432 mtx_unlock(&bqlock);
1434 if ((bp->b_flags & B_INVAL) || !(bp->b_flags & B_DELWRI))
1438 * Something we can maybe free or reuse.
1440 if (bp->b_bufsize && !(bp->b_flags & B_DELWRI))
1443 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF);
1444 if ((bp->b_flags & B_DELWRI) == 0 && (bp->b_xflags & BX_VNDIRTY))
1445 panic("bqrelse: not dirty");
1450 /* Give pages used by the bp back to the VM system (where possible) */
1452 vfs_vmio_release(struct buf *bp)
1457 VM_OBJECT_LOCK(bp->b_bufobj->bo_object);
1458 vm_page_lock_queues();
1459 for (i = 0; i < bp->b_npages; i++) {
1461 bp->b_pages[i] = NULL;
1463 * In order to keep page LRU ordering consistent, put
1464 * everything on the inactive queue.
1466 vm_page_unwire(m, 0);
1468 * We don't mess with busy pages, it is
1469 * the responsibility of the process that
1470 * busied the pages to deal with them.
1472 if ((m->flags & PG_BUSY) || (m->busy != 0))
1475 if (m->wire_count == 0) {
1477 * Might as well free the page if we can and it has
1478 * no valid data. We also free the page if the
1479 * buffer was used for direct I/O
1481 if ((bp->b_flags & B_ASYNC) == 0 && !m->valid &&
1482 m->hold_count == 0) {
1485 } else if (bp->b_flags & B_DIRECT) {
1486 vm_page_try_to_free(m);
1487 } else if (vm_page_count_severe()) {
1488 vm_page_try_to_cache(m);
1492 vm_page_unlock_queues();
1493 VM_OBJECT_UNLOCK(bp->b_bufobj->bo_object);
1494 pmap_qremove(trunc_page((vm_offset_t) bp->b_data), bp->b_npages);
1496 if (bp->b_bufsize) {
1501 bp->b_flags &= ~B_VMIO;
1507 * Check to see if a block at a particular lbn is available for a clustered
1511 vfs_bio_clcheck(struct vnode *vp, int size, daddr_t lblkno, daddr_t blkno)
1518 /* If the buf isn't in core skip it */
1519 if ((bpa = gbincore(&vp->v_bufobj, lblkno)) == NULL)
1522 /* If the buf is busy we don't want to wait for it */
1523 if (BUF_LOCK(bpa, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0)
1526 /* Only cluster with valid clusterable delayed write buffers */
1527 if ((bpa->b_flags & (B_DELWRI | B_CLUSTEROK | B_INVAL)) !=
1528 (B_DELWRI | B_CLUSTEROK))
1531 if (bpa->b_bufsize != size)
1535 * Check to see if it is in the expected place on disk and that the
1536 * block has been mapped.
1538 if ((bpa->b_blkno != bpa->b_lblkno) && (bpa->b_blkno == blkno))
1548 * Implement clustered async writes for clearing out B_DELWRI buffers.
1549 * This is much better then the old way of writing only one buffer at
1550 * a time. Note that we may not be presented with the buffers in the
1551 * correct order, so we search for the cluster in both directions.
1554 vfs_bio_awrite(struct buf *bp)
1558 daddr_t lblkno = bp->b_lblkno;
1559 struct vnode *vp = bp->b_vp;
1566 * right now we support clustered writing only to regular files. If
1567 * we find a clusterable block we could be in the middle of a cluster
1568 * rather then at the beginning.
1570 if ((vp->v_type == VREG) &&
1571 (vp->v_mount != 0) && /* Only on nodes that have the size info */
1572 (bp->b_flags & (B_CLUSTEROK | B_INVAL)) == B_CLUSTEROK) {
1574 size = vp->v_mount->mnt_stat.f_iosize;
1575 maxcl = MAXPHYS / size;
1578 for (i = 1; i < maxcl; i++)
1579 if (vfs_bio_clcheck(vp, size, lblkno + i,
1580 bp->b_blkno + ((i * size) >> DEV_BSHIFT)) == 0)
1583 for (j = 1; i + j <= maxcl && j <= lblkno; j++)
1584 if (vfs_bio_clcheck(vp, size, lblkno - j,
1585 bp->b_blkno - ((j * size) >> DEV_BSHIFT)) == 0)
1592 * this is a possible cluster write
1596 nwritten = cluster_wbuild(vp, size, lblkno - j, ncl);
1601 bp->b_flags |= B_ASYNC;
1603 * default (old) behavior, writing out only one block
1605 * XXX returns b_bufsize instead of b_bcount for nwritten?
1607 nwritten = bp->b_bufsize;
1616 * Find and initialize a new buffer header, freeing up existing buffers
1617 * in the bufqueues as necessary. The new buffer is returned locked.
1619 * Important: B_INVAL is not set. If the caller wishes to throw the
1620 * buffer away, the caller must set B_INVAL prior to calling brelse().
1623 * We have insufficient buffer headers
1624 * We have insufficient buffer space
1625 * buffer_map is too fragmented ( space reservation fails )
1626 * If we have to flush dirty buffers ( but we try to avoid this )
1628 * To avoid VFS layer recursion we do not flush dirty buffers ourselves.
1629 * Instead we ask the buf daemon to do it for us. We attempt to
1630 * avoid piecemeal wakeups of the pageout daemon.
1634 getnewbuf(int slpflag, int slptimeo, int size, int maxsize)
1640 static int flushingbufs;
1643 * We can't afford to block since we might be holding a vnode lock,
1644 * which may prevent system daemons from running. We deal with
1645 * low-memory situations by proactively returning memory and running
1646 * async I/O rather then sync I/O.
1649 atomic_add_int(&getnewbufcalls, 1);
1650 atomic_subtract_int(&getnewbufrestarts, 1);
1652 atomic_add_int(&getnewbufrestarts, 1);
1655 * Setup for scan. If we do not have enough free buffers,
1656 * we setup a degenerate case that immediately fails. Note
1657 * that if we are specially marked process, we are allowed to
1658 * dip into our reserves.
1660 * The scanning sequence is nominally: EMPTY->EMPTYKVA->CLEAN
1662 * We start with EMPTYKVA. If the list is empty we backup to EMPTY.
1663 * However, there are a number of cases (defragging, reusing, ...)
1664 * where we cannot backup.
1667 nqindex = QUEUE_EMPTYKVA;
1668 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTYKVA]);
1672 * If no EMPTYKVA buffers and we are either
1673 * defragging or reusing, locate a CLEAN buffer
1674 * to free or reuse. If bufspace useage is low
1675 * skip this step so we can allocate a new buffer.
1677 if (defrag || bufspace >= lobufspace) {
1678 nqindex = QUEUE_CLEAN;
1679 nbp = TAILQ_FIRST(&bufqueues[QUEUE_CLEAN]);
1683 * If we could not find or were not allowed to reuse a
1684 * CLEAN buffer, check to see if it is ok to use an EMPTY
1685 * buffer. We can only use an EMPTY buffer if allocating
1686 * its KVA would not otherwise run us out of buffer space.
1688 if (nbp == NULL && defrag == 0 &&
1689 bufspace + maxsize < hibufspace) {
1690 nqindex = QUEUE_EMPTY;
1691 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTY]);
1696 * Run scan, possibly freeing data and/or kva mappings on the fly
1700 while ((bp = nbp) != NULL) {
1701 int qindex = nqindex;
1704 * Calculate next bp ( we can only use it if we do not block
1705 * or do other fancy things ).
1707 if ((nbp = TAILQ_NEXT(bp, b_freelist)) == NULL) {
1710 nqindex = QUEUE_EMPTYKVA;
1711 if ((nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTYKVA])))
1714 case QUEUE_EMPTYKVA:
1715 nqindex = QUEUE_CLEAN;
1716 if ((nbp = TAILQ_FIRST(&bufqueues[QUEUE_CLEAN])))
1727 * If we are defragging then we need a buffer with
1728 * b_kvasize != 0. XXX this situation should no longer
1729 * occur, if defrag is non-zero the buffer's b_kvasize
1730 * should also be non-zero at this point. XXX
1732 if (defrag && bp->b_kvasize == 0) {
1733 printf("Warning: defrag empty buffer %p\n", bp);
1738 * Start freeing the bp. This is somewhat involved. nbp
1739 * remains valid only for QUEUE_EMPTY[KVA] bp's.
1741 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0)
1744 BO_LOCK(bp->b_bufobj);
1745 if (bp->b_vflags & BV_BKGRDINPROG) {
1746 BO_UNLOCK(bp->b_bufobj);
1750 BO_UNLOCK(bp->b_bufobj);
1753 "getnewbuf(%p) vp %p flags %X kvasize %d bufsize %d "
1754 "queue %d (recycling)", bp, bp->b_vp, bp->b_flags,
1755 bp->b_kvasize, bp->b_bufsize, qindex);
1760 KASSERT(bp->b_qindex == qindex, ("getnewbuf: inconsistant queue %d bp %p", qindex, bp));
1763 * Note: we no longer distinguish between VMIO and non-VMIO
1767 KASSERT((bp->b_flags & B_DELWRI) == 0, ("delwri buffer %p found in queue %d", bp, qindex));
1770 mtx_unlock(&bqlock);
1772 if (qindex == QUEUE_CLEAN) {
1773 if (bp->b_flags & B_VMIO) {
1774 bp->b_flags &= ~B_ASYNC;
1775 vfs_vmio_release(bp);
1782 * NOTE: nbp is now entirely invalid. We can only restart
1783 * the scan from this point on.
1785 * Get the rest of the buffer freed up. b_kva* is still
1786 * valid after this operation.
1789 if (bp->b_rcred != NOCRED) {
1790 crfree(bp->b_rcred);
1791 bp->b_rcred = NOCRED;
1793 if (bp->b_wcred != NOCRED) {
1794 crfree(bp->b_wcred);
1795 bp->b_wcred = NOCRED;
1797 if (LIST_FIRST(&bp->b_dep) != NULL)
1799 if (bp->b_vflags & BV_BKGRDINPROG)
1800 panic("losing buffer 3");
1801 KASSERT(bp->b_vp == NULL,
1802 ("bp: %p still has vnode %p. qindex: %d",
1803 bp, bp->b_vp, qindex));
1804 KASSERT((bp->b_xflags & (BX_VNCLEAN|BX_VNDIRTY)) == 0,
1805 ("bp: %p still on a buffer list. xflags %X",
1816 bp->b_blkno = bp->b_lblkno = 0;
1817 bp->b_offset = NOOFFSET;
1823 bp->b_dirtyoff = bp->b_dirtyend = 0;
1824 bp->b_bufobj = NULL;
1826 LIST_INIT(&bp->b_dep);
1829 * If we are defragging then free the buffer.
1832 bp->b_flags |= B_INVAL;
1840 * If we are overcomitted then recover the buffer and its
1841 * KVM space. This occurs in rare situations when multiple
1842 * processes are blocked in getnewbuf() or allocbuf().
1844 if (bufspace >= hibufspace)
1846 if (flushingbufs && bp->b_kvasize != 0) {
1847 bp->b_flags |= B_INVAL;
1852 if (bufspace < lobufspace)
1858 * If we exhausted our list, sleep as appropriate. We may have to
1859 * wakeup various daemons and write out some dirty buffers.
1861 * Generally we are sleeping due to insufficient buffer space.
1868 mtx_unlock(&bqlock);
1870 flags = VFS_BIO_NEED_BUFSPACE;
1872 } else if (bufspace >= hibufspace) {
1874 flags = VFS_BIO_NEED_BUFSPACE;
1877 flags = VFS_BIO_NEED_ANY;
1880 bd_speedup(); /* heeeelp */
1883 needsbuffer |= flags;
1884 while (needsbuffer & flags) {
1885 if (msleep(&needsbuffer, &nblock,
1886 (PRIBIO + 4) | slpflag, waitmsg, slptimeo)) {
1887 mtx_unlock(&nblock);
1891 mtx_unlock(&nblock);
1894 * We finally have a valid bp. We aren't quite out of the
1895 * woods, we still have to reserve kva space. In order
1896 * to keep fragmentation sane we only allocate kva in
1899 maxsize = (maxsize + BKVAMASK) & ~BKVAMASK;
1901 if (maxsize != bp->b_kvasize) {
1902 vm_offset_t addr = 0;
1906 vm_map_lock(buffer_map);
1907 if (vm_map_findspace(buffer_map,
1908 vm_map_min(buffer_map), maxsize, &addr)) {
1910 * Uh oh. Buffer map is to fragmented. We
1911 * must defragment the map.
1913 atomic_add_int(&bufdefragcnt, 1);
1914 vm_map_unlock(buffer_map);
1916 bp->b_flags |= B_INVAL;
1921 vm_map_insert(buffer_map, NULL, 0,
1922 addr, addr + maxsize,
1923 VM_PROT_ALL, VM_PROT_ALL, MAP_NOFAULT);
1925 bp->b_kvabase = (caddr_t) addr;
1926 bp->b_kvasize = maxsize;
1927 atomic_add_int(&bufspace, bp->b_kvasize);
1928 atomic_add_int(&bufreusecnt, 1);
1930 vm_map_unlock(buffer_map);
1932 bp->b_saveaddr = bp->b_kvabase;
1933 bp->b_data = bp->b_saveaddr;
1941 * buffer flushing daemon. Buffers are normally flushed by the
1942 * update daemon but if it cannot keep up this process starts to
1943 * take the load in an attempt to prevent getnewbuf() from blocking.
1946 static struct kproc_desc buf_kp = {
1951 SYSINIT(bufdaemon, SI_SUB_KTHREAD_BUF, SI_ORDER_FIRST, kproc_start, &buf_kp)
1959 * This process needs to be suspended prior to shutdown sync.
1961 EVENTHANDLER_REGISTER(shutdown_pre_sync, kproc_shutdown, bufdaemonproc,
1965 * This process is allowed to take the buffer cache to the limit
1970 mtx_unlock(&bdlock);
1972 kthread_suspend_check(bufdaemonproc);
1975 * Do the flush. Limit the amount of in-transit I/O we
1976 * allow to build up, otherwise we would completely saturate
1977 * the I/O system. Wakeup any waiting processes before we
1978 * normally would so they can run in parallel with our drain.
1980 while (numdirtybuffers > lodirtybuffers) {
1981 if (flushbufqueues(0) == 0) {
1983 * Could not find any buffers without rollback
1984 * dependencies, so just write the first one
1985 * in the hopes of eventually making progress.
1994 * Only clear bd_request if we have reached our low water
1995 * mark. The buf_daemon normally waits 1 second and
1996 * then incrementally flushes any dirty buffers that have
1997 * built up, within reason.
1999 * If we were unable to hit our low water mark and couldn't
2000 * find any flushable buffers, we sleep half a second.
2001 * Otherwise we loop immediately.
2004 if (numdirtybuffers <= lodirtybuffers) {
2006 * We reached our low water mark, reset the
2007 * request and sleep until we are needed again.
2008 * The sleep is just so the suspend code works.
2011 msleep(&bd_request, &bdlock, PVM, "psleep", hz);
2014 * We couldn't find any flushable dirty buffers but
2015 * still have too many dirty buffers, we
2016 * have to sleep and try again. (rare)
2018 msleep(&bd_request, &bdlock, PVM, "qsleep", hz / 10);
2026 * Try to flush a buffer in the dirty queue. We must be careful to
2027 * free up B_INVAL buffers instead of write them, which NFS is
2028 * particularly sensitive to.
2030 static int flushwithdeps = 0;
2031 SYSCTL_INT(_vfs, OID_AUTO, flushwithdeps, CTLFLAG_RW, &flushwithdeps,
2032 0, "Number of buffers flushed with dependecies that require rollbacks");
2035 flushbufqueues(int flushdeps)
2037 struct thread *td = curthread;
2038 struct buf sentinel;
2046 target = numdirtybuffers - lodirtybuffers;
2047 if (flushdeps && target > 2)
2052 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_DIRTY], &sentinel, b_freelist);
2053 while (flushed != target) {
2054 bp = TAILQ_FIRST(&bufqueues[QUEUE_DIRTY]);
2055 if (bp == &sentinel)
2057 TAILQ_REMOVE(&bufqueues[QUEUE_DIRTY], bp, b_freelist);
2058 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_DIRTY], bp, b_freelist);
2060 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0)
2062 BO_LOCK(bp->b_bufobj);
2063 if ((bp->b_vflags & BV_BKGRDINPROG) != 0 ||
2064 (bp->b_flags & B_DELWRI) == 0) {
2065 BO_UNLOCK(bp->b_bufobj);
2069 BO_UNLOCK(bp->b_bufobj);
2070 if (bp->b_flags & B_INVAL) {
2072 mtx_unlock(&bqlock);
2075 numdirtywakeup((lodirtybuffers + hidirtybuffers) / 2);
2080 if (LIST_FIRST(&bp->b_dep) != NULL && buf_countdeps(bp, 0)) {
2081 if (flushdeps == 0) {
2089 * We must hold the lock on a vnode before writing
2090 * one of its buffers. Otherwise we may confuse, or
2091 * in the case of a snapshot vnode, deadlock the
2094 * The lock order here is the reverse of the normal
2095 * of vnode followed by buf lock. This is ok because
2096 * the NOWAIT will prevent deadlock.
2099 if (vn_start_write(vp, &mp, V_NOWAIT) != 0) {
2103 if (vn_lock(vp, LK_EXCLUSIVE | LK_NOWAIT, td) == 0) {
2104 mtx_unlock(&bqlock);
2105 CTR3(KTR_BUF, "flushbufqueue(%p) vp %p flags %X",
2106 bp, bp->b_vp, bp->b_flags);
2108 vn_finished_write(mp);
2109 VOP_UNLOCK(vp, 0, td);
2110 flushwithdeps += hasdeps;
2112 waitrunningbufspace();
2113 numdirtywakeup((lodirtybuffers + hidirtybuffers) / 2);
2117 vn_finished_write(mp);
2120 TAILQ_REMOVE(&bufqueues[QUEUE_DIRTY], &sentinel, b_freelist);
2121 mtx_unlock(&bqlock);
2126 * Check to see if a block is currently memory resident.
2129 incore(struct bufobj *bo, daddr_t blkno)
2134 bp = gbincore(bo, blkno);
2140 * Returns true if no I/O is needed to access the
2141 * associated VM object. This is like incore except
2142 * it also hunts around in the VM system for the data.
2146 inmem(struct vnode * vp, daddr_t blkno)
2149 vm_offset_t toff, tinc, size;
2153 ASSERT_VOP_LOCKED(vp, "inmem");
2155 if (incore(&vp->v_bufobj, blkno))
2157 if (vp->v_mount == NULL)
2164 if (size > vp->v_mount->mnt_stat.f_iosize)
2165 size = vp->v_mount->mnt_stat.f_iosize;
2166 off = (vm_ooffset_t)blkno * (vm_ooffset_t)vp->v_mount->mnt_stat.f_iosize;
2168 VM_OBJECT_LOCK(obj);
2169 for (toff = 0; toff < vp->v_mount->mnt_stat.f_iosize; toff += tinc) {
2170 m = vm_page_lookup(obj, OFF_TO_IDX(off + toff));
2174 if (tinc > PAGE_SIZE - ((toff + off) & PAGE_MASK))
2175 tinc = PAGE_SIZE - ((toff + off) & PAGE_MASK);
2176 if (vm_page_is_valid(m,
2177 (vm_offset_t) ((toff + off) & PAGE_MASK), tinc) == 0)
2180 VM_OBJECT_UNLOCK(obj);
2184 VM_OBJECT_UNLOCK(obj);
2191 * Sets the dirty range for a buffer based on the status of the dirty
2192 * bits in the pages comprising the buffer.
2194 * The range is limited to the size of the buffer.
2196 * This routine is primarily used by NFS, but is generalized for the
2200 vfs_setdirty(struct buf *bp)
2206 * Degenerate case - empty buffer
2209 if (bp->b_bufsize == 0)
2213 * We qualify the scan for modified pages on whether the
2214 * object has been flushed yet. The OBJ_WRITEABLE flag
2215 * is not cleared simply by protecting pages off.
2218 if ((bp->b_flags & B_VMIO) == 0)
2221 object = bp->b_pages[0]->object;
2222 VM_OBJECT_LOCK(object);
2223 if ((object->flags & OBJ_WRITEABLE) && !(object->flags & OBJ_MIGHTBEDIRTY))
2224 printf("Warning: object %p writeable but not mightbedirty\n", object);
2225 if (!(object->flags & OBJ_WRITEABLE) && (object->flags & OBJ_MIGHTBEDIRTY))
2226 printf("Warning: object %p mightbedirty but not writeable\n", object);
2228 if (object->flags & (OBJ_MIGHTBEDIRTY|OBJ_CLEANING)) {
2229 vm_offset_t boffset;
2230 vm_offset_t eoffset;
2232 vm_page_lock_queues();
2234 * test the pages to see if they have been modified directly
2235 * by users through the VM system.
2237 for (i = 0; i < bp->b_npages; i++)
2238 vm_page_test_dirty(bp->b_pages[i]);
2241 * Calculate the encompassing dirty range, boffset and eoffset,
2242 * (eoffset - boffset) bytes.
2245 for (i = 0; i < bp->b_npages; i++) {
2246 if (bp->b_pages[i]->dirty)
2249 boffset = (i << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK);
2251 for (i = bp->b_npages - 1; i >= 0; --i) {
2252 if (bp->b_pages[i]->dirty) {
2256 eoffset = ((i + 1) << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK);
2258 vm_page_unlock_queues();
2260 * Fit it to the buffer.
2263 if (eoffset > bp->b_bcount)
2264 eoffset = bp->b_bcount;
2267 * If we have a good dirty range, merge with the existing
2271 if (boffset < eoffset) {
2272 if (bp->b_dirtyoff > boffset)
2273 bp->b_dirtyoff = boffset;
2274 if (bp->b_dirtyend < eoffset)
2275 bp->b_dirtyend = eoffset;
2278 VM_OBJECT_UNLOCK(object);
2284 * Get a block given a specified block and offset into a file/device.
2285 * The buffers B_DONE bit will be cleared on return, making it almost
2286 * ready for an I/O initiation. B_INVAL may or may not be set on
2287 * return. The caller should clear B_INVAL prior to initiating a
2290 * For a non-VMIO buffer, B_CACHE is set to the opposite of B_INVAL for
2291 * an existing buffer.
2293 * For a VMIO buffer, B_CACHE is modified according to the backing VM.
2294 * If getblk()ing a previously 0-sized invalid buffer, B_CACHE is set
2295 * and then cleared based on the backing VM. If the previous buffer is
2296 * non-0-sized but invalid, B_CACHE will be cleared.
2298 * If getblk() must create a new buffer, the new buffer is returned with
2299 * both B_INVAL and B_CACHE clear unless it is a VMIO buffer, in which
2300 * case it is returned with B_INVAL clear and B_CACHE set based on the
2303 * getblk() also forces a bwrite() for any B_DELWRI buffer whos
2304 * B_CACHE bit is clear.
2306 * What this means, basically, is that the caller should use B_CACHE to
2307 * determine whether the buffer is fully valid or not and should clear
2308 * B_INVAL prior to issuing a read. If the caller intends to validate
2309 * the buffer by loading its data area with something, the caller needs
2310 * to clear B_INVAL. If the caller does this without issuing an I/O,
2311 * the caller should set B_CACHE ( as an optimization ), else the caller
2312 * should issue the I/O and biodone() will set B_CACHE if the I/O was
2313 * a write attempt or if it was a successfull read. If the caller
2314 * intends to issue a READ, the caller must clear B_INVAL and BIO_ERROR
2315 * prior to issuing the READ. biodone() will *not* clear B_INVAL.
2318 getblk(struct vnode * vp, daddr_t blkno, int size, int slpflag, int slptimeo,
2325 CTR3(KTR_BUF, "getblk(%p, %ld, %d)", vp, (long)blkno, size);
2326 ASSERT_VOP_LOCKED(vp, "getblk");
2327 if (size > MAXBSIZE)
2328 panic("getblk: size(%d) > MAXBSIZE(%d)\n", size, MAXBSIZE);
2333 * Block if we are low on buffers. Certain processes are allowed
2334 * to completely exhaust the buffer cache.
2336 * If this check ever becomes a bottleneck it may be better to
2337 * move it into the else, when gbincore() fails. At the moment
2338 * it isn't a problem.
2340 * XXX remove if 0 sections (clean this up after its proven)
2342 if (numfreebuffers == 0) {
2343 if (curthread == PCPU_GET(idlethread))
2346 needsbuffer |= VFS_BIO_NEED_ANY;
2347 mtx_unlock(&nblock);
2351 bp = gbincore(bo, blkno);
2355 * Buffer is in-core. If the buffer is not busy, it must
2358 lockflags = LK_EXCLUSIVE | LK_SLEEPFAIL | LK_INTERLOCK;
2360 if (flags & GB_LOCK_NOWAIT)
2361 lockflags |= LK_NOWAIT;
2363 error = BUF_TIMELOCK(bp, lockflags,
2364 VI_MTX(vp), "getblk", slpflag, slptimeo);
2367 * If we slept and got the lock we have to restart in case
2368 * the buffer changed identities.
2370 if (error == ENOLCK)
2372 /* We timed out or were interrupted. */
2377 * The buffer is locked. B_CACHE is cleared if the buffer is
2378 * invalid. Otherwise, for a non-VMIO buffer, B_CACHE is set
2379 * and for a VMIO buffer B_CACHE is adjusted according to the
2382 if (bp->b_flags & B_INVAL)
2383 bp->b_flags &= ~B_CACHE;
2384 else if ((bp->b_flags & (B_VMIO | B_INVAL)) == 0)
2385 bp->b_flags |= B_CACHE;
2389 * check for size inconsistancies for non-VMIO case.
2392 if (bp->b_bcount != size) {
2393 if ((bp->b_flags & B_VMIO) == 0 ||
2394 (size > bp->b_kvasize)) {
2395 if (bp->b_flags & B_DELWRI) {
2396 bp->b_flags |= B_NOCACHE;
2399 if ((bp->b_flags & B_VMIO) &&
2400 (LIST_FIRST(&bp->b_dep) == NULL)) {
2401 bp->b_flags |= B_RELBUF;
2404 bp->b_flags |= B_NOCACHE;
2413 * If the size is inconsistant in the VMIO case, we can resize
2414 * the buffer. This might lead to B_CACHE getting set or
2415 * cleared. If the size has not changed, B_CACHE remains
2416 * unchanged from its previous state.
2419 if (bp->b_bcount != size)
2422 KASSERT(bp->b_offset != NOOFFSET,
2423 ("getblk: no buffer offset"));
2426 * A buffer with B_DELWRI set and B_CACHE clear must
2427 * be committed before we can return the buffer in
2428 * order to prevent the caller from issuing a read
2429 * ( due to B_CACHE not being set ) and overwriting
2432 * Most callers, including NFS and FFS, need this to
2433 * operate properly either because they assume they
2434 * can issue a read if B_CACHE is not set, or because
2435 * ( for example ) an uncached B_DELWRI might loop due
2436 * to softupdates re-dirtying the buffer. In the latter
2437 * case, B_CACHE is set after the first write completes,
2438 * preventing further loops.
2439 * NOTE! b*write() sets B_CACHE. If we cleared B_CACHE
2440 * above while extending the buffer, we cannot allow the
2441 * buffer to remain with B_CACHE set after the write
2442 * completes or it will represent a corrupt state. To
2443 * deal with this we set B_NOCACHE to scrap the buffer
2446 * We might be able to do something fancy, like setting
2447 * B_CACHE in bwrite() except if B_DELWRI is already set,
2448 * so the below call doesn't set B_CACHE, but that gets real
2449 * confusing. This is much easier.
2452 if ((bp->b_flags & (B_CACHE|B_DELWRI)) == B_DELWRI) {
2453 bp->b_flags |= B_NOCACHE;
2457 bp->b_flags &= ~B_DONE;
2459 int bsize, maxsize, vmio;
2463 * Buffer is not in-core, create new buffer. The buffer
2464 * returned by getnewbuf() is locked. Note that the returned
2465 * buffer is also considered valid (not marked B_INVAL).
2469 * If the user does not want us to create the buffer, bail out
2472 if (flags & GB_NOCREAT)
2474 bsize = bo->bo_bsize;
2475 offset = blkno * bsize;
2476 vmio = vp->v_object != NULL;
2477 maxsize = vmio ? size + (offset & PAGE_MASK) : size;
2478 maxsize = imax(maxsize, bsize);
2480 bp = getnewbuf(slpflag, slptimeo, size, maxsize);
2482 if (slpflag || slptimeo)
2488 * This code is used to make sure that a buffer is not
2489 * created while the getnewbuf routine is blocked.
2490 * This can be a problem whether the vnode is locked or not.
2491 * If the buffer is created out from under us, we have to
2492 * throw away the one we just created.
2494 * Note: this must occur before we associate the buffer
2495 * with the vp especially considering limitations in
2496 * the splay tree implementation when dealing with duplicate
2500 if (gbincore(bo, blkno)) {
2502 bp->b_flags |= B_INVAL;
2508 * Insert the buffer into the hash, so that it can
2509 * be found by incore.
2511 bp->b_blkno = bp->b_lblkno = blkno;
2512 bp->b_offset = offset;
2518 * set B_VMIO bit. allocbuf() the buffer bigger. Since the
2519 * buffer size starts out as 0, B_CACHE will be set by
2520 * allocbuf() for the VMIO case prior to it testing the
2521 * backing store for validity.
2525 bp->b_flags |= B_VMIO;
2526 #if defined(VFS_BIO_DEBUG)
2527 if (vn_canvmio(vp) != TRUE)
2528 printf("getblk: VMIO on vnode type %d\n",
2531 KASSERT(vp->v_object == bp->b_bufobj->bo_object,
2532 ("ARGH! different b_bufobj->bo_object %p %p %p\n",
2533 bp, vp->v_object, bp->b_bufobj->bo_object));
2535 bp->b_flags &= ~B_VMIO;
2536 KASSERT(bp->b_bufobj->bo_object == NULL,
2537 ("ARGH! has b_bufobj->bo_object %p %p\n",
2538 bp, bp->b_bufobj->bo_object));
2542 bp->b_flags &= ~B_DONE;
2544 CTR4(KTR_BUF, "getblk(%p, %ld, %d) = %p", vp, (long)blkno, size, bp);
2545 KASSERT(BUF_REFCNT(bp) == 1, ("getblk: bp %p not locked",bp));
2546 KASSERT(bp->b_bufobj == bo,
2547 ("bp %p wrong b_bufobj %p should be %p", bp, bp->b_bufobj, bo));
2552 * Get an empty, disassociated buffer of given size. The buffer is initially
2561 maxsize = (size + BKVAMASK) & ~BKVAMASK;
2562 while ((bp = getnewbuf(0, 0, size, maxsize)) == 0)
2565 bp->b_flags |= B_INVAL; /* b_dep cleared by getnewbuf() */
2566 KASSERT(BUF_REFCNT(bp) == 1, ("geteblk: bp %p not locked",bp));
2572 * This code constitutes the buffer memory from either anonymous system
2573 * memory (in the case of non-VMIO operations) or from an associated
2574 * VM object (in the case of VMIO operations). This code is able to
2575 * resize a buffer up or down.
2577 * Note that this code is tricky, and has many complications to resolve
2578 * deadlock or inconsistant data situations. Tread lightly!!!
2579 * There are B_CACHE and B_DELWRI interactions that must be dealt with by
2580 * the caller. Calling this code willy nilly can result in the loss of data.
2582 * allocbuf() only adjusts B_CACHE for VMIO buffers. getblk() deals with
2583 * B_CACHE for the non-VMIO case.
2587 allocbuf(struct buf *bp, int size)
2589 int newbsize, mbsize;
2592 if (BUF_REFCNT(bp) == 0)
2593 panic("allocbuf: buffer not busy");
2595 if (bp->b_kvasize < size)
2596 panic("allocbuf: buffer too small");
2598 if ((bp->b_flags & B_VMIO) == 0) {
2602 * Just get anonymous memory from the kernel. Don't
2603 * mess with B_CACHE.
2605 mbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1);
2606 if (bp->b_flags & B_MALLOC)
2609 newbsize = round_page(size);
2611 if (newbsize < bp->b_bufsize) {
2613 * malloced buffers are not shrunk
2615 if (bp->b_flags & B_MALLOC) {
2617 bp->b_bcount = size;
2619 free(bp->b_data, M_BIOBUF);
2620 if (bp->b_bufsize) {
2621 atomic_subtract_int(
2627 bp->b_saveaddr = bp->b_kvabase;
2628 bp->b_data = bp->b_saveaddr;
2630 bp->b_flags &= ~B_MALLOC;
2636 (vm_offset_t) bp->b_data + newbsize,
2637 (vm_offset_t) bp->b_data + bp->b_bufsize);
2638 } else if (newbsize > bp->b_bufsize) {
2640 * We only use malloced memory on the first allocation.
2641 * and revert to page-allocated memory when the buffer
2645 * There is a potential smp race here that could lead
2646 * to bufmallocspace slightly passing the max. It
2647 * is probably extremely rare and not worth worrying
2650 if ( (bufmallocspace < maxbufmallocspace) &&
2651 (bp->b_bufsize == 0) &&
2652 (mbsize <= PAGE_SIZE/2)) {
2654 bp->b_data = malloc(mbsize, M_BIOBUF, M_WAITOK);
2655 bp->b_bufsize = mbsize;
2656 bp->b_bcount = size;
2657 bp->b_flags |= B_MALLOC;
2658 atomic_add_int(&bufmallocspace, mbsize);
2664 * If the buffer is growing on its other-than-first allocation,
2665 * then we revert to the page-allocation scheme.
2667 if (bp->b_flags & B_MALLOC) {
2668 origbuf = bp->b_data;
2669 origbufsize = bp->b_bufsize;
2670 bp->b_data = bp->b_kvabase;
2671 if (bp->b_bufsize) {
2672 atomic_subtract_int(&bufmallocspace,
2677 bp->b_flags &= ~B_MALLOC;
2678 newbsize = round_page(newbsize);
2682 (vm_offset_t) bp->b_data + bp->b_bufsize,
2683 (vm_offset_t) bp->b_data + newbsize);
2685 bcopy(origbuf, bp->b_data, origbufsize);
2686 free(origbuf, M_BIOBUF);
2692 newbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1);
2693 desiredpages = (size == 0) ? 0 :
2694 num_pages((bp->b_offset & PAGE_MASK) + newbsize);
2696 if (bp->b_flags & B_MALLOC)
2697 panic("allocbuf: VMIO buffer can't be malloced");
2699 * Set B_CACHE initially if buffer is 0 length or will become
2702 if (size == 0 || bp->b_bufsize == 0)
2703 bp->b_flags |= B_CACHE;
2705 if (newbsize < bp->b_bufsize) {
2707 * DEV_BSIZE aligned new buffer size is less then the
2708 * DEV_BSIZE aligned existing buffer size. Figure out
2709 * if we have to remove any pages.
2711 if (desiredpages < bp->b_npages) {
2714 VM_OBJECT_LOCK(bp->b_bufobj->bo_object);
2715 vm_page_lock_queues();
2716 for (i = desiredpages; i < bp->b_npages; i++) {
2718 * the page is not freed here -- it
2719 * is the responsibility of
2720 * vnode_pager_setsize
2723 KASSERT(m != bogus_page,
2724 ("allocbuf: bogus page found"));
2725 while (vm_page_sleep_if_busy(m, TRUE, "biodep"))
2726 vm_page_lock_queues();
2728 bp->b_pages[i] = NULL;
2729 vm_page_unwire(m, 0);
2731 vm_page_unlock_queues();
2732 VM_OBJECT_UNLOCK(bp->b_bufobj->bo_object);
2733 pmap_qremove((vm_offset_t) trunc_page((vm_offset_t)bp->b_data) +
2734 (desiredpages << PAGE_SHIFT), (bp->b_npages - desiredpages));
2735 bp->b_npages = desiredpages;
2737 } else if (size > bp->b_bcount) {
2739 * We are growing the buffer, possibly in a
2740 * byte-granular fashion.
2748 * Step 1, bring in the VM pages from the object,
2749 * allocating them if necessary. We must clear
2750 * B_CACHE if these pages are not valid for the
2751 * range covered by the buffer.
2755 obj = bp->b_bufobj->bo_object;
2757 VM_OBJECT_LOCK(obj);
2758 while (bp->b_npages < desiredpages) {
2762 pi = OFF_TO_IDX(bp->b_offset) + bp->b_npages;
2763 if ((m = vm_page_lookup(obj, pi)) == NULL) {
2765 * note: must allocate system pages
2766 * since blocking here could intefere
2767 * with paging I/O, no matter which
2770 m = vm_page_alloc(obj, pi,
2771 VM_ALLOC_NOBUSY | VM_ALLOC_SYSTEM |
2774 atomic_add_int(&vm_pageout_deficit,
2775 desiredpages - bp->b_npages);
2776 VM_OBJECT_UNLOCK(obj);
2778 VM_OBJECT_LOCK(obj);
2780 bp->b_flags &= ~B_CACHE;
2781 bp->b_pages[bp->b_npages] = m;
2788 * We found a page. If we have to sleep on it,
2789 * retry because it might have gotten freed out
2792 * We can only test PG_BUSY here. Blocking on
2793 * m->busy might lead to a deadlock:
2795 * vm_fault->getpages->cluster_read->allocbuf
2798 vm_page_lock_queues();
2799 if (vm_page_sleep_if_busy(m, FALSE, "pgtblk"))
2803 * We have a good page. Should we wakeup the
2806 if ((curproc != pageproc) &&
2807 ((m->queue - m->pc) == PQ_CACHE) &&
2808 ((cnt.v_free_count + cnt.v_cache_count) <
2809 (cnt.v_free_min + cnt.v_cache_min))) {
2810 pagedaemon_wakeup();
2813 vm_page_unlock_queues();
2814 bp->b_pages[bp->b_npages] = m;
2819 * Step 2. We've loaded the pages into the buffer,
2820 * we have to figure out if we can still have B_CACHE
2821 * set. Note that B_CACHE is set according to the
2822 * byte-granular range ( bcount and size ), new the
2823 * aligned range ( newbsize ).
2825 * The VM test is against m->valid, which is DEV_BSIZE
2826 * aligned. Needless to say, the validity of the data
2827 * needs to also be DEV_BSIZE aligned. Note that this
2828 * fails with NFS if the server or some other client
2829 * extends the file's EOF. If our buffer is resized,
2830 * B_CACHE may remain set! XXX
2833 toff = bp->b_bcount;
2834 tinc = PAGE_SIZE - ((bp->b_offset + toff) & PAGE_MASK);
2836 while ((bp->b_flags & B_CACHE) && toff < size) {
2839 if (tinc > (size - toff))
2842 pi = ((bp->b_offset & PAGE_MASK) + toff) >>
2855 VM_OBJECT_UNLOCK(obj);
2858 * Step 3, fixup the KVM pmap. Remember that
2859 * bp->b_data is relative to bp->b_offset, but
2860 * bp->b_offset may be offset into the first page.
2863 bp->b_data = (caddr_t)
2864 trunc_page((vm_offset_t)bp->b_data);
2866 (vm_offset_t)bp->b_data,
2871 bp->b_data = (caddr_t)((vm_offset_t)bp->b_data |
2872 (vm_offset_t)(bp->b_offset & PAGE_MASK));
2875 if (newbsize < bp->b_bufsize)
2877 bp->b_bufsize = newbsize; /* actual buffer allocation */
2878 bp->b_bcount = size; /* requested buffer size */
2883 biodone(struct bio *bp)
2886 mtx_lock(&bdonelock);
2887 bp->bio_flags |= BIO_DONE;
2888 if (bp->bio_done == NULL)
2890 mtx_unlock(&bdonelock);
2891 if (bp->bio_done != NULL)
2896 * Wait for a BIO to finish.
2898 * XXX: resort to a timeout for now. The optimal locking (if any) for this
2899 * case is not yet clear.
2902 biowait(struct bio *bp, const char *wchan)
2905 mtx_lock(&bdonelock);
2906 while ((bp->bio_flags & BIO_DONE) == 0)
2907 msleep(bp, &bdonelock, PRIBIO, wchan, hz / 10);
2908 mtx_unlock(&bdonelock);
2909 if (bp->bio_error != 0)
2910 return (bp->bio_error);
2911 if (!(bp->bio_flags & BIO_ERROR))
2917 biofinish(struct bio *bp, struct devstat *stat, int error)
2921 bp->bio_error = error;
2922 bp->bio_flags |= BIO_ERROR;
2925 devstat_end_transaction_bio(stat, bp);
2932 * Wait for buffer I/O completion, returning error status. The buffer
2933 * is left locked and B_DONE on return. B_EINTR is converted into an EINTR
2934 * error and cleared.
2937 bufwait(struct buf *bp)
2939 if (bp->b_iocmd == BIO_READ)
2940 bwait(bp, PRIBIO, "biord");
2942 bwait(bp, PRIBIO, "biowr");
2943 if (bp->b_flags & B_EINTR) {
2944 bp->b_flags &= ~B_EINTR;
2947 if (bp->b_ioflags & BIO_ERROR) {
2948 return (bp->b_error ? bp->b_error : EIO);
2955 * Call back function from struct bio back up to struct buf.
2958 bufdonebio(struct bio *bip)
2962 bp = bip->bio_caller2;
2963 bp->b_resid = bp->b_bcount - bip->bio_completed;
2964 bp->b_resid = bip->bio_resid; /* XXX: remove */
2965 bp->b_ioflags = bip->bio_flags;
2966 bp->b_error = bip->bio_error;
2968 bp->b_ioflags |= BIO_ERROR;
2974 dev_strategy(struct cdev *dev, struct buf *bp)
2979 if ((!bp->b_iocmd) || (bp->b_iocmd & (bp->b_iocmd - 1)))
2980 panic("b_iocmd botch");
2985 /* Try again later */
2986 tsleep(&bp, PRIBIO, "dev_strat", hz/10);
2988 bip->bio_cmd = bp->b_iocmd;
2989 bip->bio_offset = bp->b_iooffset;
2990 bip->bio_length = bp->b_bcount;
2991 bip->bio_bcount = bp->b_bcount; /* XXX: remove */
2992 bip->bio_data = bp->b_data;
2993 bip->bio_done = bufdonebio;
2994 bip->bio_caller2 = bp;
2996 KASSERT(dev->si_refcount > 0,
2997 ("dev_strategy on un-referenced struct cdev *(%s)",
2999 csw = dev_refthread(dev);
3001 bp->b_error = ENXIO;
3002 bp->b_ioflags = BIO_ERROR;
3006 (*csw->d_strategy)(bip);
3013 * Finish I/O on a buffer, optionally calling a completion function.
3014 * This is usually called from an interrupt so process blocking is
3017 * biodone is also responsible for setting B_CACHE in a B_VMIO bp.
3018 * In a non-VMIO bp, B_CACHE will be set on the next getblk()
3019 * assuming B_INVAL is clear.
3021 * For the VMIO case, we set B_CACHE if the op was a read and no
3022 * read error occured, or if the op was a write. B_CACHE is never
3023 * set if the buffer is invalid or otherwise uncacheable.
3025 * biodone does not mess with B_INVAL, allowing the I/O routine or the
3026 * initiator to leave B_INVAL set to brelse the buffer out of existance
3027 * in the biodone routine.
3030 bufdone(struct buf *bp)
3032 struct bufobj *dropobj;
3033 void (*biodone)(struct buf *);
3036 CTR3(KTR_BUF, "bufdone(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
3039 KASSERT(BUF_REFCNT(bp) > 0, ("biodone: bp %p not busy %d", bp, BUF_REFCNT(bp)));
3040 KASSERT(!(bp->b_flags & B_DONE), ("biodone: bp %p already done", bp));
3042 runningbufwakeup(bp);
3043 if (bp->b_iocmd == BIO_WRITE)
3044 dropobj = bp->b_bufobj;
3045 /* call optional completion function if requested */
3046 if (bp->b_iodone != NULL) {
3047 biodone = bp->b_iodone;
3048 bp->b_iodone = NULL;
3051 bufobj_wdrop(dropobj);
3054 if (LIST_FIRST(&bp->b_dep) != NULL)
3057 if (bp->b_flags & B_VMIO) {
3063 struct vnode *vp = bp->b_vp;
3065 obj = bp->b_bufobj->bo_object;
3067 #if defined(VFS_BIO_DEBUG)
3068 mp_fixme("usecount and vflag accessed without locks.");
3069 if (vp->v_usecount == 0) {
3070 panic("biodone: zero vnode ref count");
3073 KASSERT(vp->v_object != NULL,
3074 ("biodone: vnode %p has no vm_object", vp));
3077 foff = bp->b_offset;
3078 KASSERT(bp->b_offset != NOOFFSET,
3079 ("biodone: no buffer offset"));
3081 VM_OBJECT_LOCK(obj);
3082 #if defined(VFS_BIO_DEBUG)
3083 if (obj->paging_in_progress < bp->b_npages) {
3084 printf("biodone: paging in progress(%d) < bp->b_npages(%d)\n",
3085 obj->paging_in_progress, bp->b_npages);
3090 * Set B_CACHE if the op was a normal read and no error
3091 * occured. B_CACHE is set for writes in the b*write()
3094 iosize = bp->b_bcount - bp->b_resid;
3095 if (bp->b_iocmd == BIO_READ &&
3096 !(bp->b_flags & (B_INVAL|B_NOCACHE)) &&
3097 !(bp->b_ioflags & BIO_ERROR)) {
3098 bp->b_flags |= B_CACHE;
3100 vm_page_lock_queues();
3101 for (i = 0; i < bp->b_npages; i++) {
3105 resid = ((foff + PAGE_SIZE) & ~(off_t)PAGE_MASK) - foff;
3110 * cleanup bogus pages, restoring the originals
3113 if (m == bogus_page) {
3115 m = vm_page_lookup(obj, OFF_TO_IDX(foff));
3117 panic("biodone: page disappeared!");
3119 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), bp->b_pages, bp->b_npages);
3121 #if defined(VFS_BIO_DEBUG)
3122 if (OFF_TO_IDX(foff) != m->pindex) {
3124 "biodone: foff(%jd)/m->pindex(%ju) mismatch\n",
3125 (intmax_t)foff, (uintmax_t)m->pindex);
3130 * In the write case, the valid and clean bits are
3131 * already changed correctly ( see bdwrite() ), so we
3132 * only need to do this here in the read case.
3134 if ((bp->b_iocmd == BIO_READ) && !bogusflag && resid > 0) {
3135 vfs_page_set_valid(bp, foff, i, m);
3139 * when debugging new filesystems or buffer I/O methods, this
3140 * is the most common error that pops up. if you see this, you
3141 * have not set the page busy flag correctly!!!
3144 printf("biodone: page busy < 0, "
3145 "pindex: %d, foff: 0x(%x,%x), "
3146 "resid: %d, index: %d\n",
3147 (int) m->pindex, (int)(foff >> 32),
3148 (int) foff & 0xffffffff, resid, i);
3149 if (!vn_isdisk(vp, NULL))
3150 printf(" iosize: %jd, lblkno: %jd, flags: 0x%x, npages: %d\n",
3151 (intmax_t)bp->b_vp->v_mount->mnt_stat.f_iosize,
3152 (intmax_t) bp->b_lblkno,
3153 bp->b_flags, bp->b_npages);
3155 printf(" VDEV, lblkno: %jd, flags: 0x%x, npages: %d\n",
3156 (intmax_t) bp->b_lblkno,
3157 bp->b_flags, bp->b_npages);
3158 printf(" valid: 0x%lx, dirty: 0x%lx, wired: %d\n",
3159 (u_long)m->valid, (u_long)m->dirty,
3161 panic("biodone: page busy < 0\n");
3163 vm_page_io_finish(m);
3164 vm_object_pip_subtract(obj, 1);
3165 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK;
3168 vm_page_unlock_queues();
3169 vm_object_pip_wakeupn(obj, 0);
3170 VM_OBJECT_UNLOCK(obj);
3174 * For asynchronous completions, release the buffer now. The brelse
3175 * will do a wakeup there if necessary - so no need to do a wakeup
3176 * here in the async case. The sync case always needs to do a wakeup.
3179 if (bp->b_flags & B_ASYNC) {
3180 if ((bp->b_flags & (B_NOCACHE | B_INVAL | B_RELBUF)) || (bp->b_ioflags & BIO_ERROR))
3187 bufobj_wdrop(dropobj);
3191 * This routine is called in lieu of iodone in the case of
3192 * incomplete I/O. This keeps the busy status for pages
3196 vfs_unbusy_pages(struct buf *bp)
3202 runningbufwakeup(bp);
3203 if (!(bp->b_flags & B_VMIO))
3206 obj = bp->b_bufobj->bo_object;
3207 VM_OBJECT_LOCK(obj);
3208 vm_page_lock_queues();
3209 for (i = 0; i < bp->b_npages; i++) {
3211 if (m == bogus_page) {
3212 m = vm_page_lookup(obj, OFF_TO_IDX(bp->b_offset) + i);
3214 panic("vfs_unbusy_pages: page missing\n");
3216 pmap_qenter(trunc_page((vm_offset_t)bp->b_data),
3217 bp->b_pages, bp->b_npages);
3219 vm_object_pip_subtract(obj, 1);
3220 vm_page_io_finish(m);
3222 vm_page_unlock_queues();
3223 vm_object_pip_wakeupn(obj, 0);
3224 VM_OBJECT_UNLOCK(obj);
3228 * vfs_page_set_valid:
3230 * Set the valid bits in a page based on the supplied offset. The
3231 * range is restricted to the buffer's size.
3233 * This routine is typically called after a read completes.
3236 vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, int pageno, vm_page_t m)
3238 vm_ooffset_t soff, eoff;
3240 mtx_assert(&vm_page_queue_mtx, MA_OWNED);
3242 * Start and end offsets in buffer. eoff - soff may not cross a
3243 * page boundry or cross the end of the buffer. The end of the
3244 * buffer, in this case, is our file EOF, not the allocation size
3248 eoff = (off + PAGE_SIZE) & ~(off_t)PAGE_MASK;
3249 if (eoff > bp->b_offset + bp->b_bcount)
3250 eoff = bp->b_offset + bp->b_bcount;
3253 * Set valid range. This is typically the entire buffer and thus the
3257 vm_page_set_validclean(
3259 (vm_offset_t) (soff & PAGE_MASK),
3260 (vm_offset_t) (eoff - soff)
3266 * This routine is called before a device strategy routine.
3267 * It is used to tell the VM system that paging I/O is in
3268 * progress, and treat the pages associated with the buffer
3269 * almost as being PG_BUSY. Also the object paging_in_progress
3270 * flag is handled to make sure that the object doesn't become
3273 * Since I/O has not been initiated yet, certain buffer flags
3274 * such as BIO_ERROR or B_INVAL may be in an inconsistant state
3275 * and should be ignored.
3278 vfs_busy_pages(struct buf *bp, int clear_modify)
3285 if (!(bp->b_flags & B_VMIO))
3288 obj = bp->b_bufobj->bo_object;
3289 foff = bp->b_offset;
3290 KASSERT(bp->b_offset != NOOFFSET,
3291 ("vfs_busy_pages: no buffer offset"));
3293 VM_OBJECT_LOCK(obj);
3295 vm_page_lock_queues();
3296 for (i = 0; i < bp->b_npages; i++) {
3299 if (vm_page_sleep_if_busy(m, FALSE, "vbpage"))
3303 for (i = 0; i < bp->b_npages; i++) {
3306 if ((bp->b_flags & B_CLUSTER) == 0) {
3307 vm_object_pip_add(obj, 1);
3308 vm_page_io_start(m);
3311 * When readying a buffer for a read ( i.e
3312 * clear_modify == 0 ), it is important to do
3313 * bogus_page replacement for valid pages in
3314 * partially instantiated buffers. Partially
3315 * instantiated buffers can, in turn, occur when
3316 * reconstituting a buffer from its VM backing store
3317 * base. We only have to do this if B_CACHE is
3318 * clear ( which causes the I/O to occur in the
3319 * first place ). The replacement prevents the read
3320 * I/O from overwriting potentially dirty VM-backed
3321 * pages. XXX bogus page replacement is, uh, bogus.
3322 * It may not work properly with small-block devices.
3323 * We need to find a better way.
3327 vfs_page_set_valid(bp, foff, i, m);
3328 else if (m->valid == VM_PAGE_BITS_ALL &&
3329 (bp->b_flags & B_CACHE) == 0) {
3330 bp->b_pages[i] = bogus_page;
3333 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK;
3335 vm_page_unlock_queues();
3336 VM_OBJECT_UNLOCK(obj);
3338 pmap_qenter(trunc_page((vm_offset_t)bp->b_data),
3339 bp->b_pages, bp->b_npages);
3343 * Tell the VM system that the pages associated with this buffer
3344 * are clean. This is used for delayed writes where the data is
3345 * going to go to disk eventually without additional VM intevention.
3347 * Note that while we only really need to clean through to b_bcount, we
3348 * just go ahead and clean through to b_bufsize.
3351 vfs_clean_pages(struct buf *bp)
3354 vm_ooffset_t foff, noff, eoff;
3357 if (!(bp->b_flags & B_VMIO))
3360 foff = bp->b_offset;
3361 KASSERT(bp->b_offset != NOOFFSET,
3362 ("vfs_clean_pages: no buffer offset"));
3363 VM_OBJECT_LOCK(bp->b_bufobj->bo_object);
3364 vm_page_lock_queues();
3365 for (i = 0; i < bp->b_npages; i++) {
3367 noff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK;
3370 if (eoff > bp->b_offset + bp->b_bufsize)
3371 eoff = bp->b_offset + bp->b_bufsize;
3372 vfs_page_set_valid(bp, foff, i, m);
3373 /* vm_page_clear_dirty(m, foff & PAGE_MASK, eoff - foff); */
3376 vm_page_unlock_queues();
3377 VM_OBJECT_UNLOCK(bp->b_bufobj->bo_object);
3381 * vfs_bio_set_validclean:
3383 * Set the range within the buffer to valid and clean. The range is
3384 * relative to the beginning of the buffer, b_offset. Note that b_offset
3385 * itself may be offset from the beginning of the first page.
3390 vfs_bio_set_validclean(struct buf *bp, int base, int size)
3395 if (!(bp->b_flags & B_VMIO))
3398 * Fixup base to be relative to beginning of first page.
3399 * Set initial n to be the maximum number of bytes in the
3400 * first page that can be validated.
3403 base += (bp->b_offset & PAGE_MASK);
3404 n = PAGE_SIZE - (base & PAGE_MASK);
3406 VM_OBJECT_LOCK(bp->b_bufobj->bo_object);
3407 vm_page_lock_queues();
3408 for (i = base / PAGE_SIZE; size > 0 && i < bp->b_npages; ++i) {
3412 vm_page_set_validclean(m, base & PAGE_MASK, n);
3417 vm_page_unlock_queues();
3418 VM_OBJECT_UNLOCK(bp->b_bufobj->bo_object);
3424 * clear a buffer. This routine essentially fakes an I/O, so we need
3425 * to clear BIO_ERROR and B_INVAL.
3427 * Note that while we only theoretically need to clear through b_bcount,
3428 * we go ahead and clear through b_bufsize.
3432 vfs_bio_clrbuf(struct buf *bp)
3437 if ((bp->b_flags & (B_VMIO | B_MALLOC)) != B_VMIO) {
3442 bp->b_flags &= ~B_INVAL;
3443 bp->b_ioflags &= ~BIO_ERROR;
3444 VM_OBJECT_LOCK(bp->b_bufobj->bo_object);
3445 if ((bp->b_npages == 1) && (bp->b_bufsize < PAGE_SIZE) &&
3446 (bp->b_offset & PAGE_MASK) == 0) {
3447 if (bp->b_pages[0] == bogus_page)
3449 mask = (1 << (bp->b_bufsize / DEV_BSIZE)) - 1;
3450 VM_OBJECT_LOCK_ASSERT(bp->b_pages[0]->object, MA_OWNED);
3451 if ((bp->b_pages[0]->valid & mask) == mask)
3453 if (((bp->b_pages[0]->flags & PG_ZERO) == 0) &&
3454 ((bp->b_pages[0]->valid & mask) == 0)) {
3455 bzero(bp->b_data, bp->b_bufsize);
3456 bp->b_pages[0]->valid |= mask;
3460 ea = sa = bp->b_data;
3461 for(i = 0; i < bp->b_npages; i++, sa = ea) {
3462 ea = (caddr_t)trunc_page((vm_offset_t)sa + PAGE_SIZE);
3463 ea = (caddr_t)(vm_offset_t)ulmin(
3464 (u_long)(vm_offset_t)ea,
3465 (u_long)(vm_offset_t)bp->b_data + bp->b_bufsize);
3466 if (bp->b_pages[i] == bogus_page)
3468 j = ((vm_offset_t)sa & PAGE_MASK) / DEV_BSIZE;
3469 mask = ((1 << ((ea - sa) / DEV_BSIZE)) - 1) << j;
3470 VM_OBJECT_LOCK_ASSERT(bp->b_pages[i]->object, MA_OWNED);
3471 if ((bp->b_pages[i]->valid & mask) == mask)
3473 if ((bp->b_pages[i]->valid & mask) == 0) {
3474 if ((bp->b_pages[i]->flags & PG_ZERO) == 0)
3477 for (; sa < ea; sa += DEV_BSIZE, j++) {
3478 if (((bp->b_pages[i]->flags & PG_ZERO) == 0) &&
3479 (bp->b_pages[i]->valid & (1 << j)) == 0)
3480 bzero(sa, DEV_BSIZE);
3483 bp->b_pages[i]->valid |= mask;
3486 VM_OBJECT_UNLOCK(bp->b_bufobj->bo_object);
3491 * vm_hold_load_pages and vm_hold_free_pages get pages into
3492 * a buffers address space. The pages are anonymous and are
3493 * not associated with a file object.
3496 vm_hold_load_pages(struct buf *bp, vm_offset_t from, vm_offset_t to)
3502 to = round_page(to);
3503 from = round_page(from);
3504 index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT;
3506 VM_OBJECT_LOCK(kernel_object);
3507 for (pg = from; pg < to; pg += PAGE_SIZE, index++) {
3510 * note: must allocate system pages since blocking here
3511 * could intefere with paging I/O, no matter which
3514 p = vm_page_alloc(kernel_object,
3515 ((pg - VM_MIN_KERNEL_ADDRESS) >> PAGE_SHIFT),
3516 VM_ALLOC_NOBUSY | VM_ALLOC_SYSTEM | VM_ALLOC_WIRED);
3518 atomic_add_int(&vm_pageout_deficit,
3519 (to - pg) >> PAGE_SHIFT);
3520 VM_OBJECT_UNLOCK(kernel_object);
3522 VM_OBJECT_LOCK(kernel_object);
3525 p->valid = VM_PAGE_BITS_ALL;
3526 pmap_qenter(pg, &p, 1);
3527 bp->b_pages[index] = p;
3529 VM_OBJECT_UNLOCK(kernel_object);
3530 bp->b_npages = index;
3533 /* Return pages associated with this buf to the vm system */
3535 vm_hold_free_pages(struct buf *bp, vm_offset_t from, vm_offset_t to)
3539 int index, newnpages;
3541 from = round_page(from);
3542 to = round_page(to);
3543 newnpages = index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT;
3545 VM_OBJECT_LOCK(kernel_object);
3546 for (pg = from; pg < to; pg += PAGE_SIZE, index++) {
3547 p = bp->b_pages[index];
3548 if (p && (index < bp->b_npages)) {
3551 "vm_hold_free_pages: blkno: %jd, lblkno: %jd\n",
3552 (intmax_t)bp->b_blkno,
3553 (intmax_t)bp->b_lblkno);
3555 bp->b_pages[index] = NULL;
3556 pmap_qremove(pg, 1);
3557 vm_page_lock_queues();
3558 vm_page_unwire(p, 0);
3560 vm_page_unlock_queues();
3563 VM_OBJECT_UNLOCK(kernel_object);
3564 bp->b_npages = newnpages;
3568 * Map an IO request into kernel virtual address space.
3570 * All requests are (re)mapped into kernel VA space.
3571 * Notice that we use b_bufsize for the size of the buffer
3572 * to be mapped. b_bcount might be modified by the driver.
3574 * Note that even if the caller determines that the address space should
3575 * be valid, a race or a smaller-file mapped into a larger space may
3576 * actually cause vmapbuf() to fail, so all callers of vmapbuf() MUST
3577 * check the return value.
3580 vmapbuf(struct buf *bp)
3586 struct pmap *pmap = &curproc->p_vmspace->vm_pmap;
3588 if (bp->b_bufsize < 0)
3590 prot = VM_PROT_READ;
3591 if (bp->b_iocmd == BIO_READ)
3592 prot |= VM_PROT_WRITE; /* Less backwards than it looks */
3593 for (addr = (caddr_t)trunc_page((vm_offset_t)bp->b_data), pidx = 0;
3594 addr < bp->b_data + bp->b_bufsize;
3595 addr += PAGE_SIZE, pidx++) {
3597 * Do the vm_fault if needed; do the copy-on-write thing
3598 * when reading stuff off device into memory.
3600 * NOTE! Must use pmap_extract() because addr may be in
3601 * the userland address space, and kextract is only guarenteed
3602 * to work for the kernland address space (see: sparc64 port).
3605 if (vm_fault_quick(addr >= bp->b_data ? addr : bp->b_data,
3607 vm_page_lock_queues();
3608 for (i = 0; i < pidx; ++i) {
3609 vm_page_unhold(bp->b_pages[i]);
3610 bp->b_pages[i] = NULL;
3612 vm_page_unlock_queues();
3615 m = pmap_extract_and_hold(pmap, (vm_offset_t)addr, prot);
3618 bp->b_pages[pidx] = m;
3620 if (pidx > btoc(MAXPHYS))
3621 panic("vmapbuf: mapped more than MAXPHYS");
3622 pmap_qenter((vm_offset_t)bp->b_saveaddr, bp->b_pages, pidx);
3624 kva = bp->b_saveaddr;
3625 bp->b_npages = pidx;
3626 bp->b_saveaddr = bp->b_data;
3627 bp->b_data = kva + (((vm_offset_t) bp->b_data) & PAGE_MASK);
3632 * Free the io map PTEs associated with this IO operation.
3633 * We also invalidate the TLB entries and restore the original b_addr.
3636 vunmapbuf(struct buf *bp)
3641 npages = bp->b_npages;
3642 pmap_qremove(trunc_page((vm_offset_t)bp->b_data), npages);
3643 vm_page_lock_queues();
3644 for (pidx = 0; pidx < npages; pidx++)
3645 vm_page_unhold(bp->b_pages[pidx]);
3646 vm_page_unlock_queues();
3648 bp->b_data = bp->b_saveaddr;
3652 bdone(struct buf *bp)
3655 mtx_lock(&bdonelock);
3656 bp->b_flags |= B_DONE;
3658 mtx_unlock(&bdonelock);
3662 bwait(struct buf *bp, u_char pri, const char *wchan)
3665 mtx_lock(&bdonelock);
3666 while ((bp->b_flags & B_DONE) == 0)
3667 msleep(bp, &bdonelock, pri, wchan, 0);
3668 mtx_unlock(&bdonelock);
3672 bufsync(struct bufobj *bo, int waitfor, struct thread *td)
3675 return (VOP_FSYNC(bo->__bo_vnode, waitfor, td));
3679 bufstrategy(struct bufobj *bo, struct buf *bp)
3685 KASSERT(vp == bo->bo_private, ("Inconsistent vnode bufstrategy"));
3686 KASSERT(vp->v_type != VCHR && vp->v_type != VBLK,
3687 ("Wrong vnode in bufstrategy(bp=%p, vp=%p)", bp, vp));
3688 i = VOP_STRATEGY(vp, bp);
3689 KASSERT(i == 0, ("VOP_STRATEGY failed bp=%p vp=%p", bp, bp->b_vp));
3693 bufobj_wrefl(struct bufobj *bo)
3696 KASSERT(bo != NULL, ("NULL bo in bufobj_wref"));
3697 ASSERT_BO_LOCKED(bo);
3702 bufobj_wref(struct bufobj *bo)
3705 KASSERT(bo != NULL, ("NULL bo in bufobj_wref"));
3712 bufobj_wdrop(struct bufobj *bo)
3715 KASSERT(bo != NULL, ("NULL bo in bufobj_wdrop"));
3717 KASSERT(bo->bo_numoutput > 0, ("bufobj_wdrop non-positive count"));
3718 if ((--bo->bo_numoutput == 0) && (bo->bo_flag & BO_WWAIT)) {
3719 bo->bo_flag &= ~BO_WWAIT;
3720 wakeup(&bo->bo_numoutput);
3726 bufobj_wwait(struct bufobj *bo, int slpflag, int timeo)
3730 KASSERT(bo != NULL, ("NULL bo in bufobj_wwait"));
3731 ASSERT_BO_LOCKED(bo);
3733 while (bo->bo_numoutput) {
3734 bo->bo_flag |= BO_WWAIT;
3735 error = msleep(&bo->bo_numoutput, BO_MTX(bo),
3736 slpflag | (PRIBIO + 1), "bo_wwait", timeo);
3743 #include "opt_ddb.h"
3745 #include <ddb/ddb.h>
3747 /* DDB command to show buffer data */
3748 DB_SHOW_COMMAND(buffer, db_show_buffer)
3751 struct buf *bp = (struct buf *)addr;
3754 db_printf("usage: show buffer <addr>\n");
3758 db_printf("buf at %p\n", bp);
3759 db_printf("b_flags = 0x%b\n", (u_int)bp->b_flags, PRINT_BUF_FLAGS);
3761 "b_error = %d, b_bufsize = %ld, b_bcount = %ld, b_resid = %ld\n"
3762 "b_bufobj = (%p), b_data = %p, b_blkno = %jd\n",
3763 bp->b_error, bp->b_bufsize, bp->b_bcount, bp->b_resid,
3764 bp->b_bufobj, bp->b_data, (intmax_t)bp->b_blkno);
3767 db_printf("b_npages = %d, pages(OBJ, IDX, PA): ", bp->b_npages);
3768 for (i = 0; i < bp->b_npages; i++) {
3771 db_printf("(%p, 0x%lx, 0x%lx)", (void *)m->object,
3772 (u_long)m->pindex, (u_long)VM_PAGE_TO_PHYS(m));
3773 if ((i + 1) < bp->b_npages)
3778 lockmgr_printinfo(&bp->b_lock);
3781 DB_SHOW_COMMAND(lockedbufs, lockedbufs)
3786 for (i = 0; i < nbuf; i++) {
3788 if (lockcount(&bp->b_lock)) {
3789 db_show_buffer((uintptr_t)bp, 1, 0, NULL);