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>
51 #include <sys/limits.h>
53 #include <sys/malloc.h>
54 #include <sys/mount.h>
55 #include <sys/mutex.h>
56 #include <sys/kernel.h>
57 #include <sys/kthread.h>
59 #include <sys/resourcevar.h>
60 #include <sys/sysctl.h>
61 #include <sys/vmmeter.h>
62 #include <sys/vnode.h>
63 #include <geom/geom.h>
65 #include <vm/vm_param.h>
66 #include <vm/vm_kern.h>
67 #include <vm/vm_pageout.h>
68 #include <vm/vm_page.h>
69 #include <vm/vm_object.h>
70 #include <vm/vm_extern.h>
71 #include <vm/vm_map.h>
72 #include "opt_directio.h"
75 static MALLOC_DEFINE(M_BIOBUF, "biobuf", "BIO buffer");
77 struct bio_ops bioops; /* I/O operation notification */
79 struct buf_ops buf_ops_bio = {
80 .bop_name = "buf_ops_bio",
81 .bop_write = bufwrite,
82 .bop_strategy = bufstrategy,
84 .bop_bdflush = bufbdflush,
88 * XXX buf is global because kern_shutdown.c and ffs_checkoverlap has
89 * carnal knowledge of buffers. This knowledge should be moved to vfs_bio.c.
91 struct buf *buf; /* buffer header pool */
93 static struct proc *bufdaemonproc;
95 static int inmem(struct vnode *vp, daddr_t blkno);
96 static void vm_hold_free_pages(struct buf *bp, vm_offset_t from,
98 static void vm_hold_load_pages(struct buf *bp, vm_offset_t from,
100 static void vfs_page_set_valid(struct buf *bp, vm_ooffset_t off,
101 int pageno, vm_page_t m);
102 static void vfs_clean_pages(struct buf *bp);
103 static void vfs_setdirty(struct buf *bp);
104 static void vfs_setdirty_locked_object(struct buf *bp);
105 static void vfs_vmio_release(struct buf *bp);
106 static int vfs_bio_clcheck(struct vnode *vp, int size,
107 daddr_t lblkno, daddr_t blkno);
108 static int flushbufqueues(int, int);
109 static void buf_daemon(void);
110 static void bremfreel(struct buf *bp);
112 int vmiodirenable = TRUE;
113 SYSCTL_INT(_vfs, OID_AUTO, vmiodirenable, CTLFLAG_RW, &vmiodirenable, 0,
114 "Use the VM system for directory writes");
116 SYSCTL_INT(_vfs, OID_AUTO, runningbufspace, CTLFLAG_RD, &runningbufspace, 0,
117 "Amount of presently outstanding async buffer io");
119 SYSCTL_INT(_vfs, OID_AUTO, bufspace, CTLFLAG_RD, &bufspace, 0,
120 "Virtual memory used for buffers");
121 static int maxbufspace;
122 SYSCTL_INT(_vfs, OID_AUTO, maxbufspace, CTLFLAG_RD, &maxbufspace, 0,
123 "Maximum allowed value of bufspace (including buf_daemon)");
124 static int bufmallocspace;
125 SYSCTL_INT(_vfs, OID_AUTO, bufmallocspace, CTLFLAG_RD, &bufmallocspace, 0,
126 "Amount of malloced memory for buffers");
127 static int maxbufmallocspace;
128 SYSCTL_INT(_vfs, OID_AUTO, maxmallocbufspace, CTLFLAG_RW, &maxbufmallocspace, 0,
129 "Maximum amount of malloced memory for buffers");
130 static int lobufspace;
131 SYSCTL_INT(_vfs, OID_AUTO, lobufspace, CTLFLAG_RD, &lobufspace, 0,
132 "Minimum amount of buffers we want to have");
134 SYSCTL_INT(_vfs, OID_AUTO, hibufspace, CTLFLAG_RD, &hibufspace, 0,
135 "Maximum allowed value of bufspace (excluding buf_daemon)");
136 static int bufreusecnt;
137 SYSCTL_INT(_vfs, OID_AUTO, bufreusecnt, CTLFLAG_RW, &bufreusecnt, 0,
138 "Number of times we have reused a buffer");
139 static int buffreekvacnt;
140 SYSCTL_INT(_vfs, OID_AUTO, buffreekvacnt, CTLFLAG_RW, &buffreekvacnt, 0,
141 "Number of times we have freed the KVA space from some buffer");
142 static int bufdefragcnt;
143 SYSCTL_INT(_vfs, OID_AUTO, bufdefragcnt, CTLFLAG_RW, &bufdefragcnt, 0,
144 "Number of times we have had to repeat buffer allocation to defragment");
145 static int lorunningspace;
146 SYSCTL_INT(_vfs, OID_AUTO, lorunningspace, CTLFLAG_RW, &lorunningspace, 0,
147 "Minimum preferred space used for in-progress I/O");
148 static int hirunningspace;
149 SYSCTL_INT(_vfs, OID_AUTO, hirunningspace, CTLFLAG_RW, &hirunningspace, 0,
150 "Maximum amount of space to use for in-progress I/O");
151 int dirtybufferflushes;
152 SYSCTL_INT(_vfs, OID_AUTO, dirtybufferflushes, CTLFLAG_RW, &dirtybufferflushes,
153 0, "Number of bdwrite to bawrite conversions to limit dirty buffers");
155 SYSCTL_INT(_vfs, OID_AUTO, bdwriteskip, CTLFLAG_RW, &bdwriteskip,
156 0, "Number of buffers supplied to bdwrite with snapshot deadlock risk");
157 int altbufferflushes;
158 SYSCTL_INT(_vfs, OID_AUTO, altbufferflushes, CTLFLAG_RW, &altbufferflushes,
159 0, "Number of fsync flushes to limit dirty buffers");
160 static int recursiveflushes;
161 SYSCTL_INT(_vfs, OID_AUTO, recursiveflushes, CTLFLAG_RW, &recursiveflushes,
162 0, "Number of flushes skipped due to being recursive");
163 static int numdirtybuffers;
164 SYSCTL_INT(_vfs, OID_AUTO, numdirtybuffers, CTLFLAG_RD, &numdirtybuffers, 0,
165 "Number of buffers that are dirty (has unwritten changes) at the moment");
166 static int lodirtybuffers;
167 SYSCTL_INT(_vfs, OID_AUTO, lodirtybuffers, CTLFLAG_RW, &lodirtybuffers, 0,
168 "How many buffers we want to have free before bufdaemon can sleep");
169 static int hidirtybuffers;
170 SYSCTL_INT(_vfs, OID_AUTO, hidirtybuffers, CTLFLAG_RW, &hidirtybuffers, 0,
171 "When the number of dirty buffers is considered severe");
173 SYSCTL_INT(_vfs, OID_AUTO, dirtybufthresh, CTLFLAG_RW, &dirtybufthresh,
174 0, "Number of bdwrite to bawrite conversions to clear dirty buffers");
175 static int numfreebuffers;
176 SYSCTL_INT(_vfs, OID_AUTO, numfreebuffers, CTLFLAG_RD, &numfreebuffers, 0,
177 "Number of free buffers");
178 static int lofreebuffers;
179 SYSCTL_INT(_vfs, OID_AUTO, lofreebuffers, CTLFLAG_RW, &lofreebuffers, 0,
181 static int hifreebuffers;
182 SYSCTL_INT(_vfs, OID_AUTO, hifreebuffers, CTLFLAG_RW, &hifreebuffers, 0,
183 "XXX Complicatedly unused");
184 static int getnewbufcalls;
185 SYSCTL_INT(_vfs, OID_AUTO, getnewbufcalls, CTLFLAG_RW, &getnewbufcalls, 0,
186 "Number of calls to getnewbuf");
187 static int getnewbufrestarts;
188 SYSCTL_INT(_vfs, OID_AUTO, getnewbufrestarts, CTLFLAG_RW, &getnewbufrestarts, 0,
189 "Number of times getnewbuf has had to restart a buffer aquisition");
192 * Wakeup point for bufdaemon, as well as indicator of whether it is already
193 * active. Set to 1 when the bufdaemon is already "on" the queue, 0 when it
196 static int bd_request;
199 * This lock synchronizes access to bd_request.
201 static struct mtx bdlock;
204 * bogus page -- for I/O to/from partially complete buffers
205 * this is a temporary solution to the problem, but it is not
206 * really that bad. it would be better to split the buffer
207 * for input in the case of buffers partially already in memory,
208 * but the code is intricate enough already.
210 vm_page_t bogus_page;
213 * Synchronization (sleep/wakeup) variable for active buffer space requests.
214 * Set when wait starts, cleared prior to wakeup().
215 * Used in runningbufwakeup() and waitrunningbufspace().
217 static int runningbufreq;
220 * This lock protects the runningbufreq and synchronizes runningbufwakeup and
221 * waitrunningbufspace().
223 static struct mtx rbreqlock;
226 * Synchronization (sleep/wakeup) variable for buffer requests.
227 * Can contain the VFS_BIO_NEED flags defined below; setting/clearing is done
229 * Used in numdirtywakeup(), bufspacewakeup(), bufcountwakeup(), bwillwrite(),
230 * getnewbuf(), and getblk().
232 static int needsbuffer;
235 * Lock that protects needsbuffer and the sleeps/wakeups surrounding it.
237 static struct mtx nblock;
240 * Lock that protects against bwait()/bdone()/B_DONE races.
243 static struct mtx bdonelock;
246 * Lock that protects against bwait()/bdone()/B_DONE races.
248 static struct mtx bpinlock;
251 * Definitions for the buffer free lists.
253 #define BUFFER_QUEUES 6 /* number of free buffer queues */
255 #define QUEUE_NONE 0 /* on no queue */
256 #define QUEUE_CLEAN 1 /* non-B_DELWRI buffers */
257 #define QUEUE_DIRTY 2 /* B_DELWRI buffers */
258 #define QUEUE_DIRTY_GIANT 3 /* B_DELWRI buffers that need giant */
259 #define QUEUE_EMPTYKVA 4 /* empty buffer headers w/KVA assignment */
260 #define QUEUE_EMPTY 5 /* empty buffer headers */
262 /* Queues for free buffers with various properties */
263 static TAILQ_HEAD(bqueues, buf) bufqueues[BUFFER_QUEUES] = { { 0 } };
265 /* Lock for the bufqueues */
266 static struct mtx bqlock;
269 * Single global constant for BUF_WMESG, to avoid getting multiple references.
270 * buf_wmesg is referred from macros.
272 const char *buf_wmesg = BUF_WMESG;
274 #define VFS_BIO_NEED_ANY 0x01 /* any freeable buffer */
275 #define VFS_BIO_NEED_DIRTYFLUSH 0x02 /* waiting for dirty buffer flush */
276 #define VFS_BIO_NEED_FREE 0x04 /* wait for free bufs, hi hysteresis */
277 #define VFS_BIO_NEED_BUFSPACE 0x08 /* wait for buf space, lo hysteresis */
280 extern void ffs_rawread_setup(void);
281 #endif /* DIRECTIO */
285 * If someone is blocked due to there being too many dirty buffers,
286 * and numdirtybuffers is now reasonable, wake them up.
290 numdirtywakeup(int level)
293 if (numdirtybuffers <= level) {
295 if (needsbuffer & VFS_BIO_NEED_DIRTYFLUSH) {
296 needsbuffer &= ~VFS_BIO_NEED_DIRTYFLUSH;
297 wakeup(&needsbuffer);
306 * Called when buffer space is potentially available for recovery.
307 * getnewbuf() will block on this flag when it is unable to free
308 * sufficient buffer space. Buffer space becomes recoverable when
309 * bp's get placed back in the queues.
317 * If someone is waiting for BUF space, wake them up. Even
318 * though we haven't freed the kva space yet, the waiting
319 * process will be able to now.
322 if (needsbuffer & VFS_BIO_NEED_BUFSPACE) {
323 needsbuffer &= ~VFS_BIO_NEED_BUFSPACE;
324 wakeup(&needsbuffer);
330 * runningbufwakeup() - in-progress I/O accounting.
334 runningbufwakeup(struct buf *bp)
337 if (bp->b_runningbufspace) {
338 atomic_subtract_int(&runningbufspace, bp->b_runningbufspace);
339 bp->b_runningbufspace = 0;
340 mtx_lock(&rbreqlock);
341 if (runningbufreq && runningbufspace <= lorunningspace) {
343 wakeup(&runningbufreq);
345 mtx_unlock(&rbreqlock);
352 * Called when a buffer has been added to one of the free queues to
353 * account for the buffer and to wakeup anyone waiting for free buffers.
354 * This typically occurs when large amounts of metadata are being handled
355 * by the buffer cache ( else buffer space runs out first, usually ).
362 atomic_add_int(&numfreebuffers, 1);
365 needsbuffer &= ~VFS_BIO_NEED_ANY;
366 if (numfreebuffers >= hifreebuffers)
367 needsbuffer &= ~VFS_BIO_NEED_FREE;
368 wakeup(&needsbuffer);
374 * waitrunningbufspace()
376 * runningbufspace is a measure of the amount of I/O currently
377 * running. This routine is used in async-write situations to
378 * prevent creating huge backups of pending writes to a device.
379 * Only asynchronous writes are governed by this function.
381 * Reads will adjust runningbufspace, but will not block based on it.
382 * The read load has a side effect of reducing the allowed write load.
384 * This does NOT turn an async write into a sync write. It waits
385 * for earlier writes to complete and generally returns before the
386 * caller's write has reached the device.
389 waitrunningbufspace(void)
392 mtx_lock(&rbreqlock);
393 while (runningbufspace > hirunningspace) {
395 msleep(&runningbufreq, &rbreqlock, PVM, "wdrain", 0);
397 mtx_unlock(&rbreqlock);
402 * vfs_buf_test_cache:
404 * Called when a buffer is extended. This function clears the B_CACHE
405 * bit if the newly extended portion of the buffer does not contain
410 vfs_buf_test_cache(struct buf *bp,
411 vm_ooffset_t foff, vm_offset_t off, vm_offset_t size,
415 VM_OBJECT_LOCK_ASSERT(m->object, MA_OWNED);
416 if (bp->b_flags & B_CACHE) {
417 int base = (foff + off) & PAGE_MASK;
418 if (vm_page_is_valid(m, base, size) == 0)
419 bp->b_flags &= ~B_CACHE;
423 /* Wake up the buffer daemon if necessary */
426 bd_wakeup(int dirtybuflevel)
430 if (bd_request == 0 && numdirtybuffers >= dirtybuflevel) {
438 * bd_speedup - speedup the buffer cache flushing code
450 * Calculating buffer cache scaling values and reserve space for buffer
451 * headers. This is called during low level kernel initialization and
452 * may be called more then once. We CANNOT write to the memory area
453 * being reserved at this time.
456 kern_vfs_bio_buffer_alloc(caddr_t v, long physmem_est)
461 * physmem_est is in pages. Convert it to kilobytes (assumes
462 * PAGE_SIZE is >= 1K)
464 physmem_est = physmem_est * (PAGE_SIZE / 1024);
467 * The nominal buffer size (and minimum KVA allocation) is BKVASIZE.
468 * For the first 64MB of ram nominally allocate sufficient buffers to
469 * cover 1/4 of our ram. Beyond the first 64MB allocate additional
470 * buffers to cover 1/10 of our ram over 64MB. When auto-sizing
471 * the buffer cache we limit the eventual kva reservation to
474 * factor represents the 1/4 x ram conversion.
477 int factor = 4 * BKVASIZE / 1024;
480 if (physmem_est > 4096)
481 nbuf += min((physmem_est - 4096) / factor,
483 if (physmem_est > 65536)
484 nbuf += (physmem_est - 65536) * 2 / (factor * 5);
486 if (maxbcache && nbuf > maxbcache / BKVASIZE)
487 nbuf = maxbcache / BKVASIZE;
489 /* XXX Avoid integer overflows later on with maxbufspace. */
490 maxbuf = (INT_MAX / 3) / BKVASIZE;
497 * Do not allow the buffer_map to be more then 1/2 the size of the
500 if (nbuf > (kernel_map->max_offset - kernel_map->min_offset) /
502 nbuf = (kernel_map->max_offset - kernel_map->min_offset) /
504 printf("Warning: nbufs capped at %d\n", nbuf);
509 * swbufs are used as temporary holders for I/O, such as paging I/O.
510 * We have no less then 16 and no more then 256.
512 nswbuf = max(min(nbuf/4, 256), 16);
514 if (nswbuf < NSWBUF_MIN)
522 * Reserve space for the buffer cache buffers
525 v = (caddr_t)(swbuf + nswbuf);
527 v = (caddr_t)(buf + nbuf);
532 /* Initialize the buffer subsystem. Called before use of any buffers. */
539 mtx_init(&bqlock, "buf queue lock", NULL, MTX_DEF);
540 mtx_init(&rbreqlock, "runningbufspace lock", NULL, MTX_DEF);
541 mtx_init(&nblock, "needsbuffer lock", NULL, MTX_DEF);
542 mtx_init(&bdlock, "buffer daemon lock", NULL, MTX_DEF);
543 mtx_init(&bdonelock, "bdone lock", NULL, MTX_DEF);
544 mtx_init(&bpinlock, "bpin lock", NULL, MTX_DEF);
546 /* next, make a null set of free lists */
547 for (i = 0; i < BUFFER_QUEUES; i++)
548 TAILQ_INIT(&bufqueues[i]);
550 /* finally, initialize each buffer header and stick on empty q */
551 for (i = 0; i < nbuf; i++) {
553 bzero(bp, sizeof *bp);
554 bp->b_flags = B_INVAL; /* we're just an empty header */
555 bp->b_rcred = NOCRED;
556 bp->b_wcred = NOCRED;
557 bp->b_qindex = QUEUE_EMPTY;
560 LIST_INIT(&bp->b_dep);
562 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_EMPTY], bp, b_freelist);
566 * maxbufspace is the absolute maximum amount of buffer space we are
567 * allowed to reserve in KVM and in real terms. The absolute maximum
568 * is nominally used by buf_daemon. hibufspace is the nominal maximum
569 * used by most other processes. The differential is required to
570 * ensure that buf_daemon is able to run when other processes might
571 * be blocked waiting for buffer space.
573 * maxbufspace is based on BKVASIZE. Allocating buffers larger then
574 * this may result in KVM fragmentation which is not handled optimally
577 maxbufspace = nbuf * BKVASIZE;
578 hibufspace = imax(3 * maxbufspace / 4, maxbufspace - MAXBSIZE * 10);
579 lobufspace = hibufspace - MAXBSIZE;
581 lorunningspace = 512 * 1024;
582 hirunningspace = 1024 * 1024;
585 * Limit the amount of malloc memory since it is wired permanently into
586 * the kernel space. Even though this is accounted for in the buffer
587 * allocation, we don't want the malloced region to grow uncontrolled.
588 * The malloc scheme improves memory utilization significantly on average
589 * (small) directories.
591 maxbufmallocspace = hibufspace / 20;
594 * Reduce the chance of a deadlock occuring by limiting the number
595 * of delayed-write dirty buffers we allow to stack up.
597 hidirtybuffers = nbuf / 4 + 20;
598 dirtybufthresh = hidirtybuffers * 9 / 10;
601 * To support extreme low-memory systems, make sure hidirtybuffers cannot
602 * eat up all available buffer space. This occurs when our minimum cannot
603 * be met. We try to size hidirtybuffers to 3/4 our buffer space assuming
604 * BKVASIZE'd (8K) buffers.
606 while (hidirtybuffers * BKVASIZE > 3 * hibufspace / 4) {
607 hidirtybuffers >>= 1;
609 lodirtybuffers = hidirtybuffers / 2;
612 * Try to keep the number of free buffers in the specified range,
613 * and give special processes (e.g. like buf_daemon) access to an
616 lofreebuffers = nbuf / 18 + 5;
617 hifreebuffers = 2 * lofreebuffers;
618 numfreebuffers = nbuf;
621 * Maximum number of async ops initiated per buf_daemon loop. This is
622 * somewhat of a hack at the moment, we really need to limit ourselves
623 * based on the number of bytes of I/O in-transit that were initiated
627 bogus_page = vm_page_alloc(NULL, 0, VM_ALLOC_NOOBJ |
628 VM_ALLOC_NORMAL | VM_ALLOC_WIRED);
632 * bfreekva() - free the kva allocation for a buffer.
634 * Since this call frees up buffer space, we call bufspacewakeup().
637 bfreekva(struct buf *bp)
641 atomic_add_int(&buffreekvacnt, 1);
642 atomic_subtract_int(&bufspace, bp->b_kvasize);
643 vm_map_remove(buffer_map, (vm_offset_t) bp->b_kvabase,
644 (vm_offset_t) bp->b_kvabase + bp->b_kvasize);
653 * Mark the buffer for removal from the appropriate free list in brelse.
657 bremfree(struct buf *bp)
660 CTR3(KTR_BUF, "bremfree(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
661 KASSERT(BUF_REFCNT(bp), ("bremfree: buf must be locked."));
662 KASSERT((bp->b_flags & B_REMFREE) == 0,
663 ("bremfree: buffer %p already marked for delayed removal.", bp));
664 KASSERT(bp->b_qindex != QUEUE_NONE,
665 ("bremfree: buffer %p not on a queue.", bp));
667 bp->b_flags |= B_REMFREE;
668 /* Fixup numfreebuffers count. */
669 if ((bp->b_flags & B_INVAL) || (bp->b_flags & B_DELWRI) == 0)
670 atomic_subtract_int(&numfreebuffers, 1);
676 * Force an immediate removal from a free list. Used only in nfs when
677 * it abuses the b_freelist pointer.
680 bremfreef(struct buf *bp)
690 * Removes a buffer from the free list, must be called with the
694 bremfreel(struct buf *bp)
696 CTR3(KTR_BUF, "bremfreel(%p) vp %p flags %X",
697 bp, bp->b_vp, bp->b_flags);
698 KASSERT(BUF_REFCNT(bp), ("bremfreel: buffer %p not locked.", bp));
699 KASSERT(bp->b_qindex != QUEUE_NONE,
700 ("bremfreel: buffer %p not on a queue.", bp));
701 mtx_assert(&bqlock, MA_OWNED);
703 TAILQ_REMOVE(&bufqueues[bp->b_qindex], bp, b_freelist);
704 bp->b_qindex = QUEUE_NONE;
706 * If this was a delayed bremfree() we only need to remove the buffer
707 * from the queue and return the stats are already done.
709 if (bp->b_flags & B_REMFREE) {
710 bp->b_flags &= ~B_REMFREE;
714 * Fixup numfreebuffers count. If the buffer is invalid or not
715 * delayed-write, the buffer was free and we must decrement
718 if ((bp->b_flags & B_INVAL) || (bp->b_flags & B_DELWRI) == 0)
719 atomic_subtract_int(&numfreebuffers, 1);
724 * Get a buffer with the specified data. Look in the cache first. We
725 * must clear BIO_ERROR and B_INVAL prior to initiating I/O. If B_CACHE
726 * is set, the buffer is valid and we do not have to do anything ( see
727 * getblk() ). This is really just a special case of breadn().
730 bread(struct vnode * vp, daddr_t blkno, int size, struct ucred * cred,
734 return (breadn(vp, blkno, size, 0, 0, 0, cred, bpp));
738 * Attempt to initiate asynchronous I/O on read-ahead blocks. We must
739 * clear BIO_ERROR and B_INVAL prior to initiating I/O . If B_CACHE is set,
740 * the buffer is valid and we do not have to do anything.
743 breada(struct vnode * vp, daddr_t * rablkno, int * rabsize,
744 int cnt, struct ucred * cred)
749 for (i = 0; i < cnt; i++, rablkno++, rabsize++) {
750 if (inmem(vp, *rablkno))
752 rabp = getblk(vp, *rablkno, *rabsize, 0, 0, 0);
754 if ((rabp->b_flags & B_CACHE) == 0) {
755 if (!TD_IS_IDLETHREAD(curthread))
756 curthread->td_ru.ru_inblock++;
757 rabp->b_flags |= B_ASYNC;
758 rabp->b_flags &= ~B_INVAL;
759 rabp->b_ioflags &= ~BIO_ERROR;
760 rabp->b_iocmd = BIO_READ;
761 if (rabp->b_rcred == NOCRED && cred != NOCRED)
762 rabp->b_rcred = crhold(cred);
763 vfs_busy_pages(rabp, 0);
765 rabp->b_iooffset = dbtob(rabp->b_blkno);
774 * Operates like bread, but also starts asynchronous I/O on
778 breadn(struct vnode * vp, daddr_t blkno, int size,
779 daddr_t * rablkno, int *rabsize,
780 int cnt, struct ucred * cred, struct buf **bpp)
783 int rv = 0, readwait = 0;
785 CTR3(KTR_BUF, "breadn(%p, %jd, %d)", vp, blkno, size);
786 *bpp = bp = getblk(vp, blkno, size, 0, 0, 0);
788 /* if not found in cache, do some I/O */
789 if ((bp->b_flags & B_CACHE) == 0) {
790 if (!TD_IS_IDLETHREAD(curthread))
791 curthread->td_ru.ru_inblock++;
792 bp->b_iocmd = BIO_READ;
793 bp->b_flags &= ~B_INVAL;
794 bp->b_ioflags &= ~BIO_ERROR;
795 if (bp->b_rcred == NOCRED && cred != NOCRED)
796 bp->b_rcred = crhold(cred);
797 vfs_busy_pages(bp, 0);
798 bp->b_iooffset = dbtob(bp->b_blkno);
803 breada(vp, rablkno, rabsize, cnt, cred);
812 * Write, release buffer on completion. (Done by iodone
813 * if async). Do not bother writing anything if the buffer
816 * Note that we set B_CACHE here, indicating that buffer is
817 * fully valid and thus cacheable. This is true even of NFS
818 * now so we set it generally. This could be set either here
819 * or in biodone() since the I/O is synchronous. We put it
823 bufwrite(struct buf *bp)
829 CTR3(KTR_BUF, "bufwrite(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
830 if (bp->b_flags & B_INVAL) {
835 oldflags = bp->b_flags;
837 if (BUF_REFCNT(bp) == 0)
838 panic("bufwrite: buffer is not busy???");
840 if (bp->b_pin_count > 0)
843 KASSERT(!(bp->b_vflags & BV_BKGRDINPROG),
844 ("FFS background buffer should not get here %p", bp));
848 vp_md = vp->v_vflag & VV_MD;
852 /* Mark the buffer clean */
855 bp->b_flags &= ~B_DONE;
856 bp->b_ioflags &= ~BIO_ERROR;
857 bp->b_flags |= B_CACHE;
858 bp->b_iocmd = BIO_WRITE;
860 bufobj_wref(bp->b_bufobj);
861 vfs_busy_pages(bp, 1);
864 * Normal bwrites pipeline writes
866 bp->b_runningbufspace = bp->b_bufsize;
867 atomic_add_int(&runningbufspace, bp->b_runningbufspace);
869 if (!TD_IS_IDLETHREAD(curthread))
870 curthread->td_ru.ru_oublock++;
871 if (oldflags & B_ASYNC)
873 bp->b_iooffset = dbtob(bp->b_blkno);
876 if ((oldflags & B_ASYNC) == 0) {
877 int rtval = bufwait(bp);
882 * don't allow the async write to saturate the I/O
883 * system. We will not deadlock here because
884 * we are blocking waiting for I/O that is already in-progress
885 * to complete. We do not block here if it is the update
886 * or syncer daemon trying to clean up as that can lead
889 if ((curthread->td_pflags & TDP_NORUNNINGBUF) == 0 && !vp_md)
890 waitrunningbufspace();
897 bufbdflush(struct bufobj *bo, struct buf *bp)
901 if (bo->bo_dirty.bv_cnt > dirtybufthresh + 10) {
902 (void) VOP_FSYNC(bp->b_vp, MNT_NOWAIT, curthread);
904 } else if (bo->bo_dirty.bv_cnt > dirtybufthresh) {
907 * Try to find a buffer to flush.
909 TAILQ_FOREACH(nbp, &bo->bo_dirty.bv_hd, b_bobufs) {
910 if ((nbp->b_vflags & BV_BKGRDINPROG) ||
912 LK_EXCLUSIVE | LK_NOWAIT, NULL))
915 panic("bdwrite: found ourselves");
917 /* Don't countdeps with the bo lock held. */
918 if (buf_countdeps(nbp, 0)) {
923 if (nbp->b_flags & B_CLUSTEROK) {
929 dirtybufferflushes++;
938 * Delayed write. (Buffer is marked dirty). Do not bother writing
939 * anything if the buffer is marked invalid.
941 * Note that since the buffer must be completely valid, we can safely
942 * set B_CACHE. In fact, we have to set B_CACHE here rather then in
943 * biodone() in order to prevent getblk from writing the buffer
947 bdwrite(struct buf *bp)
949 struct thread *td = curthread;
953 CTR3(KTR_BUF, "bdwrite(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
954 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp));
955 KASSERT(BUF_REFCNT(bp) != 0, ("bdwrite: buffer is not busy"));
957 if (bp->b_flags & B_INVAL) {
963 * If we have too many dirty buffers, don't create any more.
964 * If we are wildly over our limit, then force a complete
965 * cleanup. Otherwise, just keep the situation from getting
966 * out of control. Note that we have to avoid a recursive
967 * disaster and not try to clean up after our own cleanup!
971 if ((td->td_pflags & (TDP_COWINPROGRESS|TDP_INBDFLUSH)) == 0) {
972 td->td_pflags |= TDP_INBDFLUSH;
974 td->td_pflags &= ~TDP_INBDFLUSH;
980 * Set B_CACHE, indicating that the buffer is fully valid. This is
981 * true even of NFS now.
983 bp->b_flags |= B_CACHE;
986 * This bmap keeps the system from needing to do the bmap later,
987 * perhaps when the system is attempting to do a sync. Since it
988 * is likely that the indirect block -- or whatever other datastructure
989 * that the filesystem needs is still in memory now, it is a good
990 * thing to do this. Note also, that if the pageout daemon is
991 * requesting a sync -- there might not be enough memory to do
992 * the bmap then... So, this is important to do.
994 if (vp->v_type != VCHR && bp->b_lblkno == bp->b_blkno) {
995 VOP_BMAP(vp, bp->b_lblkno, NULL, &bp->b_blkno, NULL, NULL);
999 * Set the *dirty* buffer range based upon the VM system dirty pages.
1004 * We need to do this here to satisfy the vnode_pager and the
1005 * pageout daemon, so that it thinks that the pages have been
1006 * "cleaned". Note that since the pages are in a delayed write
1007 * buffer -- the VFS layer "will" see that the pages get written
1008 * out on the next sync, or perhaps the cluster will be completed.
1010 vfs_clean_pages(bp);
1014 * Wakeup the buffer flushing daemon if we have a lot of dirty
1015 * buffers (midpoint between our recovery point and our stall
1018 bd_wakeup((lodirtybuffers + hidirtybuffers) / 2);
1021 * note: we cannot initiate I/O from a bdwrite even if we wanted to,
1022 * due to the softdep code.
1029 * Turn buffer into delayed write request. We must clear BIO_READ and
1030 * B_RELBUF, and we must set B_DELWRI. We reassign the buffer to
1031 * itself to properly update it in the dirty/clean lists. We mark it
1032 * B_DONE to ensure that any asynchronization of the buffer properly
1033 * clears B_DONE ( else a panic will occur later ).
1035 * bdirty() is kinda like bdwrite() - we have to clear B_INVAL which
1036 * might have been set pre-getblk(). Unlike bwrite/bdwrite, bdirty()
1037 * should only be called if the buffer is known-good.
1039 * Since the buffer is not on a queue, we do not update the numfreebuffers
1042 * The buffer must be on QUEUE_NONE.
1045 bdirty(struct buf *bp)
1048 CTR3(KTR_BUF, "bdirty(%p) vp %p flags %X",
1049 bp, bp->b_vp, bp->b_flags);
1050 KASSERT(BUF_REFCNT(bp) == 1, ("bdirty: bp %p not locked",bp));
1051 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp));
1052 KASSERT(bp->b_flags & B_REMFREE || bp->b_qindex == QUEUE_NONE,
1053 ("bdirty: buffer %p still on queue %d", bp, bp->b_qindex));
1054 bp->b_flags &= ~(B_RELBUF);
1055 bp->b_iocmd = BIO_WRITE;
1057 if ((bp->b_flags & B_DELWRI) == 0) {
1058 bp->b_flags |= /* XXX B_DONE | */ B_DELWRI;
1060 atomic_add_int(&numdirtybuffers, 1);
1061 bd_wakeup((lodirtybuffers + hidirtybuffers) / 2);
1068 * Clear B_DELWRI for buffer.
1070 * Since the buffer is not on a queue, we do not update the numfreebuffers
1073 * The buffer must be on QUEUE_NONE.
1077 bundirty(struct buf *bp)
1080 CTR3(KTR_BUF, "bundirty(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
1081 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp));
1082 KASSERT(bp->b_flags & B_REMFREE || bp->b_qindex == QUEUE_NONE,
1083 ("bundirty: buffer %p still on queue %d", bp, bp->b_qindex));
1084 KASSERT(BUF_REFCNT(bp) == 1, ("bundirty: bp %p not locked",bp));
1086 if (bp->b_flags & B_DELWRI) {
1087 bp->b_flags &= ~B_DELWRI;
1089 atomic_subtract_int(&numdirtybuffers, 1);
1090 numdirtywakeup(lodirtybuffers);
1093 * Since it is now being written, we can clear its deferred write flag.
1095 bp->b_flags &= ~B_DEFERRED;
1101 * Asynchronous write. Start output on a buffer, but do not wait for
1102 * it to complete. The buffer is released when the output completes.
1104 * bwrite() ( or the VOP routine anyway ) is responsible for handling
1105 * B_INVAL buffers. Not us.
1108 bawrite(struct buf *bp)
1111 bp->b_flags |= B_ASYNC;
1118 * Called prior to the locking of any vnodes when we are expecting to
1119 * write. We do not want to starve the buffer cache with too many
1120 * dirty buffers so we block here. By blocking prior to the locking
1121 * of any vnodes we attempt to avoid the situation where a locked vnode
1122 * prevents the various system daemons from flushing related buffers.
1129 if (numdirtybuffers >= hidirtybuffers) {
1131 while (numdirtybuffers >= hidirtybuffers) {
1133 needsbuffer |= VFS_BIO_NEED_DIRTYFLUSH;
1134 msleep(&needsbuffer, &nblock,
1135 (PRIBIO + 4), "flswai", 0);
1137 mtx_unlock(&nblock);
1142 * Return true if we have too many dirty buffers.
1145 buf_dirty_count_severe(void)
1148 return(numdirtybuffers >= hidirtybuffers);
1154 * Release a busy buffer and, if requested, free its resources. The
1155 * buffer will be stashed in the appropriate bufqueue[] allowing it
1156 * to be accessed later as a cache entity or reused for other purposes.
1159 brelse(struct buf *bp)
1161 CTR3(KTR_BUF, "brelse(%p) vp %p flags %X",
1162 bp, bp->b_vp, bp->b_flags);
1163 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)),
1164 ("brelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp));
1166 if (bp->b_flags & B_MANAGED) {
1171 if (bp->b_iocmd == BIO_WRITE &&
1172 (bp->b_ioflags & BIO_ERROR) &&
1173 bp->b_error != ENXIO &&
1174 !(bp->b_flags & B_INVAL)) {
1176 * Failed write, redirty. Must clear BIO_ERROR to prevent
1177 * pages from being scrapped. If B_INVAL is set then
1178 * this case is not run and the next case is run to
1179 * destroy the buffer. B_INVAL can occur if the buffer
1180 * is outside the range supported by the underlying device.
1181 * If the error is that the device went away (ENXIO), we
1182 * shouldn't redirty the buffer either, but discard the
1185 bp->b_ioflags &= ~BIO_ERROR;
1187 } else if ((bp->b_flags & (B_NOCACHE | B_INVAL)) ||
1188 (bp->b_ioflags & BIO_ERROR) || (bp->b_bufsize <= 0)) {
1190 * Either a failed I/O or we were asked to free or not
1193 bp->b_flags |= B_INVAL;
1194 if (!LIST_EMPTY(&bp->b_dep))
1196 if (bp->b_flags & B_DELWRI) {
1197 atomic_subtract_int(&numdirtybuffers, 1);
1198 numdirtywakeup(lodirtybuffers);
1200 bp->b_flags &= ~(B_DELWRI | B_CACHE);
1201 if ((bp->b_flags & B_VMIO) == 0) {
1210 * We must clear B_RELBUF if B_DELWRI is set. If vfs_vmio_release()
1211 * is called with B_DELWRI set, the underlying pages may wind up
1212 * getting freed causing a previous write (bdwrite()) to get 'lost'
1213 * because pages associated with a B_DELWRI bp are marked clean.
1215 * We still allow the B_INVAL case to call vfs_vmio_release(), even
1216 * if B_DELWRI is set.
1218 * If B_DELWRI is not set we may have to set B_RELBUF if we are low
1219 * on pages to return pages to the VM page queues.
1221 if (bp->b_flags & B_DELWRI)
1222 bp->b_flags &= ~B_RELBUF;
1223 else if (vm_page_count_severe()) {
1225 * XXX This lock may not be necessary since BKGRDINPROG
1226 * cannot be set while we hold the buf lock, it can only be
1227 * cleared if it is already pending.
1230 BO_LOCK(bp->b_bufobj);
1231 if (!(bp->b_vflags & BV_BKGRDINPROG))
1232 bp->b_flags |= B_RELBUF;
1233 BO_UNLOCK(bp->b_bufobj);
1235 bp->b_flags |= B_RELBUF;
1239 * VMIO buffer rundown. It is not very necessary to keep a VMIO buffer
1240 * constituted, not even NFS buffers now. Two flags effect this. If
1241 * B_INVAL, the struct buf is invalidated but the VM object is kept
1242 * around ( i.e. so it is trivial to reconstitute the buffer later ).
1244 * If BIO_ERROR or B_NOCACHE is set, pages in the VM object will be
1245 * invalidated. BIO_ERROR cannot be set for a failed write unless the
1246 * buffer is also B_INVAL because it hits the re-dirtying code above.
1248 * Normally we can do this whether a buffer is B_DELWRI or not. If
1249 * the buffer is an NFS buffer, it is tracking piecemeal writes or
1250 * the commit state and we cannot afford to lose the buffer. If the
1251 * buffer has a background write in progress, we need to keep it
1252 * around to prevent it from being reconstituted and starting a second
1255 if ((bp->b_flags & B_VMIO)
1256 && !(bp->b_vp->v_mount != NULL &&
1257 (bp->b_vp->v_mount->mnt_vfc->vfc_flags & VFCF_NETWORK) != 0 &&
1258 !vn_isdisk(bp->b_vp, NULL) &&
1259 (bp->b_flags & B_DELWRI))
1268 obj = bp->b_bufobj->bo_object;
1271 * Get the base offset and length of the buffer. Note that
1272 * in the VMIO case if the buffer block size is not
1273 * page-aligned then b_data pointer may not be page-aligned.
1274 * But our b_pages[] array *IS* page aligned.
1276 * block sizes less then DEV_BSIZE (usually 512) are not
1277 * supported due to the page granularity bits (m->valid,
1278 * m->dirty, etc...).
1280 * See man buf(9) for more information
1282 resid = bp->b_bufsize;
1283 foff = bp->b_offset;
1284 VM_OBJECT_LOCK(obj);
1285 for (i = 0; i < bp->b_npages; i++) {
1291 * If we hit a bogus page, fixup *all* the bogus pages
1294 if (m == bogus_page) {
1295 poff = OFF_TO_IDX(bp->b_offset);
1298 for (j = i; j < bp->b_npages; j++) {
1300 mtmp = bp->b_pages[j];
1301 if (mtmp == bogus_page) {
1302 mtmp = vm_page_lookup(obj, poff + j);
1304 panic("brelse: page missing\n");
1306 bp->b_pages[j] = mtmp;
1310 if ((bp->b_flags & B_INVAL) == 0) {
1312 trunc_page((vm_offset_t)bp->b_data),
1313 bp->b_pages, bp->b_npages);
1317 if ((bp->b_flags & B_NOCACHE) ||
1318 (bp->b_ioflags & BIO_ERROR)) {
1319 int poffset = foff & PAGE_MASK;
1320 int presid = resid > (PAGE_SIZE - poffset) ?
1321 (PAGE_SIZE - poffset) : resid;
1323 KASSERT(presid >= 0, ("brelse: extra page"));
1324 vm_page_lock_queues();
1325 vm_page_set_invalid(m, poffset, presid);
1326 vm_page_unlock_queues();
1328 printf("avoided corruption bug in bogus_page/brelse code\n");
1330 resid -= PAGE_SIZE - (foff & PAGE_MASK);
1331 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK;
1333 VM_OBJECT_UNLOCK(obj);
1334 if (bp->b_flags & (B_INVAL | B_RELBUF))
1335 vfs_vmio_release(bp);
1337 } else if (bp->b_flags & B_VMIO) {
1339 if (bp->b_flags & (B_INVAL | B_RELBUF)) {
1340 vfs_vmio_release(bp);
1343 } else if ((bp->b_flags & (B_INVAL | B_RELBUF)) != 0) {
1344 if (bp->b_bufsize != 0)
1346 if (bp->b_vp != NULL)
1350 if (BUF_REFCNT(bp) > 1) {
1351 /* do not release to free list */
1358 /* Handle delayed bremfree() processing. */
1359 if (bp->b_flags & B_REMFREE)
1361 if (bp->b_qindex != QUEUE_NONE)
1362 panic("brelse: free buffer onto another queue???");
1364 /* buffers with no memory */
1365 if (bp->b_bufsize == 0) {
1366 bp->b_flags |= B_INVAL;
1367 bp->b_xflags &= ~(BX_BKGRDWRITE | BX_ALTDATA);
1368 if (bp->b_vflags & BV_BKGRDINPROG)
1369 panic("losing buffer 1");
1370 if (bp->b_kvasize) {
1371 bp->b_qindex = QUEUE_EMPTYKVA;
1373 bp->b_qindex = QUEUE_EMPTY;
1375 TAILQ_INSERT_HEAD(&bufqueues[bp->b_qindex], bp, b_freelist);
1376 /* buffers with junk contents */
1377 } else if (bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF) ||
1378 (bp->b_ioflags & BIO_ERROR)) {
1379 bp->b_flags |= B_INVAL;
1380 bp->b_xflags &= ~(BX_BKGRDWRITE | BX_ALTDATA);
1381 if (bp->b_vflags & BV_BKGRDINPROG)
1382 panic("losing buffer 2");
1383 bp->b_qindex = QUEUE_CLEAN;
1384 TAILQ_INSERT_HEAD(&bufqueues[QUEUE_CLEAN], bp, b_freelist);
1385 /* remaining buffers */
1387 if ((bp->b_flags & (B_DELWRI|B_NEEDSGIANT)) ==
1388 (B_DELWRI|B_NEEDSGIANT))
1389 bp->b_qindex = QUEUE_DIRTY_GIANT;
1390 else if (bp->b_flags & B_DELWRI)
1391 bp->b_qindex = QUEUE_DIRTY;
1393 bp->b_qindex = QUEUE_CLEAN;
1394 if (bp->b_flags & B_AGE)
1395 TAILQ_INSERT_HEAD(&bufqueues[bp->b_qindex], bp, b_freelist);
1397 TAILQ_INSERT_TAIL(&bufqueues[bp->b_qindex], bp, b_freelist);
1399 mtx_unlock(&bqlock);
1402 * If B_INVAL and B_DELWRI is set, clear B_DELWRI. We have already
1403 * placed the buffer on the correct queue. We must also disassociate
1404 * the device and vnode for a B_INVAL buffer so gbincore() doesn't
1407 if (bp->b_flags & B_INVAL) {
1408 if (bp->b_flags & B_DELWRI)
1415 * Fixup numfreebuffers count. The bp is on an appropriate queue
1416 * unless locked. We then bump numfreebuffers if it is not B_DELWRI.
1417 * We've already handled the B_INVAL case ( B_DELWRI will be clear
1418 * if B_INVAL is set ).
1421 if (!(bp->b_flags & B_DELWRI))
1425 * Something we can maybe free or reuse
1427 if (bp->b_bufsize || bp->b_kvasize)
1430 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF | B_DIRECT);
1431 if ((bp->b_flags & B_DELWRI) == 0 && (bp->b_xflags & BX_VNDIRTY))
1432 panic("brelse: not dirty");
1438 * Release a buffer back to the appropriate queue but do not try to free
1439 * it. The buffer is expected to be used again soon.
1441 * bqrelse() is used by bdwrite() to requeue a delayed write, and used by
1442 * biodone() to requeue an async I/O on completion. It is also used when
1443 * known good buffers need to be requeued but we think we may need the data
1446 * XXX we should be able to leave the B_RELBUF hint set on completion.
1449 bqrelse(struct buf *bp)
1451 CTR3(KTR_BUF, "bqrelse(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
1452 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)),
1453 ("bqrelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp));
1455 if (BUF_REFCNT(bp) > 1) {
1456 /* do not release to free list */
1461 if (bp->b_flags & B_MANAGED) {
1462 if (bp->b_flags & B_REMFREE) {
1465 mtx_unlock(&bqlock);
1467 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF);
1473 /* Handle delayed bremfree() processing. */
1474 if (bp->b_flags & B_REMFREE)
1476 if (bp->b_qindex != QUEUE_NONE)
1477 panic("bqrelse: free buffer onto another queue???");
1478 /* buffers with stale but valid contents */
1479 if (bp->b_flags & B_DELWRI) {
1480 if (bp->b_flags & B_NEEDSGIANT)
1481 bp->b_qindex = QUEUE_DIRTY_GIANT;
1483 bp->b_qindex = QUEUE_DIRTY;
1484 TAILQ_INSERT_TAIL(&bufqueues[bp->b_qindex], bp, b_freelist);
1487 * XXX This lock may not be necessary since BKGRDINPROG
1488 * cannot be set while we hold the buf lock, it can only be
1489 * cleared if it is already pending.
1491 BO_LOCK(bp->b_bufobj);
1492 if (!vm_page_count_severe() || bp->b_vflags & BV_BKGRDINPROG) {
1493 BO_UNLOCK(bp->b_bufobj);
1494 bp->b_qindex = QUEUE_CLEAN;
1495 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_CLEAN], bp,
1499 * We are too low on memory, we have to try to free
1500 * the buffer (most importantly: the wired pages
1501 * making up its backing store) *now*.
1503 BO_UNLOCK(bp->b_bufobj);
1504 mtx_unlock(&bqlock);
1509 mtx_unlock(&bqlock);
1511 if ((bp->b_flags & B_INVAL) || !(bp->b_flags & B_DELWRI))
1515 * Something we can maybe free or reuse.
1517 if (bp->b_bufsize && !(bp->b_flags & B_DELWRI))
1520 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF);
1521 if ((bp->b_flags & B_DELWRI) == 0 && (bp->b_xflags & BX_VNDIRTY))
1522 panic("bqrelse: not dirty");
1527 /* Give pages used by the bp back to the VM system (where possible) */
1529 vfs_vmio_release(struct buf *bp)
1534 VM_OBJECT_LOCK(bp->b_bufobj->bo_object);
1535 vm_page_lock_queues();
1536 for (i = 0; i < bp->b_npages; i++) {
1538 bp->b_pages[i] = NULL;
1540 * In order to keep page LRU ordering consistent, put
1541 * everything on the inactive queue.
1543 vm_page_unwire(m, 0);
1545 * We don't mess with busy pages, it is
1546 * the responsibility of the process that
1547 * busied the pages to deal with them.
1549 if ((m->oflags & VPO_BUSY) || (m->busy != 0))
1552 if (m->wire_count == 0) {
1554 * Might as well free the page if we can and it has
1555 * no valid data. We also free the page if the
1556 * buffer was used for direct I/O
1558 if ((bp->b_flags & B_ASYNC) == 0 && !m->valid &&
1559 m->hold_count == 0) {
1561 } else if (bp->b_flags & B_DIRECT) {
1562 vm_page_try_to_free(m);
1563 } else if (vm_page_count_severe()) {
1564 vm_page_try_to_cache(m);
1568 vm_page_unlock_queues();
1569 VM_OBJECT_UNLOCK(bp->b_bufobj->bo_object);
1570 pmap_qremove(trunc_page((vm_offset_t) bp->b_data), bp->b_npages);
1572 if (bp->b_bufsize) {
1577 bp->b_flags &= ~B_VMIO;
1583 * Check to see if a block at a particular lbn is available for a clustered
1587 vfs_bio_clcheck(struct vnode *vp, int size, daddr_t lblkno, daddr_t blkno)
1594 /* If the buf isn't in core skip it */
1595 if ((bpa = gbincore(&vp->v_bufobj, lblkno)) == NULL)
1598 /* If the buf is busy we don't want to wait for it */
1599 if (BUF_LOCK(bpa, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0)
1602 /* Only cluster with valid clusterable delayed write buffers */
1603 if ((bpa->b_flags & (B_DELWRI | B_CLUSTEROK | B_INVAL)) !=
1604 (B_DELWRI | B_CLUSTEROK))
1607 if (bpa->b_bufsize != size)
1611 * Check to see if it is in the expected place on disk and that the
1612 * block has been mapped.
1614 if ((bpa->b_blkno != bpa->b_lblkno) && (bpa->b_blkno == blkno))
1624 * Implement clustered async writes for clearing out B_DELWRI buffers.
1625 * This is much better then the old way of writing only one buffer at
1626 * a time. Note that we may not be presented with the buffers in the
1627 * correct order, so we search for the cluster in both directions.
1630 vfs_bio_awrite(struct buf *bp)
1634 daddr_t lblkno = bp->b_lblkno;
1635 struct vnode *vp = bp->b_vp;
1642 * right now we support clustered writing only to regular files. If
1643 * we find a clusterable block we could be in the middle of a cluster
1644 * rather then at the beginning.
1646 if ((vp->v_type == VREG) &&
1647 (vp->v_mount != 0) && /* Only on nodes that have the size info */
1648 (bp->b_flags & (B_CLUSTEROK | B_INVAL)) == B_CLUSTEROK) {
1650 size = vp->v_mount->mnt_stat.f_iosize;
1651 maxcl = MAXPHYS / size;
1654 for (i = 1; i < maxcl; i++)
1655 if (vfs_bio_clcheck(vp, size, lblkno + i,
1656 bp->b_blkno + ((i * size) >> DEV_BSHIFT)) == 0)
1659 for (j = 1; i + j <= maxcl && j <= lblkno; j++)
1660 if (vfs_bio_clcheck(vp, size, lblkno - j,
1661 bp->b_blkno - ((j * size) >> DEV_BSHIFT)) == 0)
1668 * this is a possible cluster write
1672 nwritten = cluster_wbuild(vp, size, lblkno - j, ncl);
1677 bp->b_flags |= B_ASYNC;
1679 * default (old) behavior, writing out only one block
1681 * XXX returns b_bufsize instead of b_bcount for nwritten?
1683 nwritten = bp->b_bufsize;
1692 * Find and initialize a new buffer header, freeing up existing buffers
1693 * in the bufqueues as necessary. The new buffer is returned locked.
1695 * Important: B_INVAL is not set. If the caller wishes to throw the
1696 * buffer away, the caller must set B_INVAL prior to calling brelse().
1699 * We have insufficient buffer headers
1700 * We have insufficient buffer space
1701 * buffer_map is too fragmented ( space reservation fails )
1702 * If we have to flush dirty buffers ( but we try to avoid this )
1704 * To avoid VFS layer recursion we do not flush dirty buffers ourselves.
1705 * Instead we ask the buf daemon to do it for us. We attempt to
1706 * avoid piecemeal wakeups of the pageout daemon.
1710 getnewbuf(int slpflag, int slptimeo, int size, int maxsize)
1716 static int flushingbufs;
1719 * We can't afford to block since we might be holding a vnode lock,
1720 * which may prevent system daemons from running. We deal with
1721 * low-memory situations by proactively returning memory and running
1722 * async I/O rather then sync I/O.
1725 atomic_add_int(&getnewbufcalls, 1);
1726 atomic_subtract_int(&getnewbufrestarts, 1);
1728 atomic_add_int(&getnewbufrestarts, 1);
1731 * Setup for scan. If we do not have enough free buffers,
1732 * we setup a degenerate case that immediately fails. Note
1733 * that if we are specially marked process, we are allowed to
1734 * dip into our reserves.
1736 * The scanning sequence is nominally: EMPTY->EMPTYKVA->CLEAN
1738 * We start with EMPTYKVA. If the list is empty we backup to EMPTY.
1739 * However, there are a number of cases (defragging, reusing, ...)
1740 * where we cannot backup.
1743 nqindex = QUEUE_EMPTYKVA;
1744 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTYKVA]);
1748 * If no EMPTYKVA buffers and we are either
1749 * defragging or reusing, locate a CLEAN buffer
1750 * to free or reuse. If bufspace useage is low
1751 * skip this step so we can allocate a new buffer.
1753 if (defrag || bufspace >= lobufspace) {
1754 nqindex = QUEUE_CLEAN;
1755 nbp = TAILQ_FIRST(&bufqueues[QUEUE_CLEAN]);
1759 * If we could not find or were not allowed to reuse a
1760 * CLEAN buffer, check to see if it is ok to use an EMPTY
1761 * buffer. We can only use an EMPTY buffer if allocating
1762 * its KVA would not otherwise run us out of buffer space.
1764 if (nbp == NULL && defrag == 0 &&
1765 bufspace + maxsize < hibufspace) {
1766 nqindex = QUEUE_EMPTY;
1767 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTY]);
1772 * Run scan, possibly freeing data and/or kva mappings on the fly
1776 while ((bp = nbp) != NULL) {
1777 int qindex = nqindex;
1780 * Calculate next bp ( we can only use it if we do not block
1781 * or do other fancy things ).
1783 if ((nbp = TAILQ_NEXT(bp, b_freelist)) == NULL) {
1786 nqindex = QUEUE_EMPTYKVA;
1787 if ((nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTYKVA])))
1790 case QUEUE_EMPTYKVA:
1791 nqindex = QUEUE_CLEAN;
1792 if ((nbp = TAILQ_FIRST(&bufqueues[QUEUE_CLEAN])))
1803 * If we are defragging then we need a buffer with
1804 * b_kvasize != 0. XXX this situation should no longer
1805 * occur, if defrag is non-zero the buffer's b_kvasize
1806 * should also be non-zero at this point. XXX
1808 if (defrag && bp->b_kvasize == 0) {
1809 printf("Warning: defrag empty buffer %p\n", bp);
1814 * Start freeing the bp. This is somewhat involved. nbp
1815 * remains valid only for QUEUE_EMPTY[KVA] bp's.
1817 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0)
1820 BO_LOCK(bp->b_bufobj);
1821 if (bp->b_vflags & BV_BKGRDINPROG) {
1822 BO_UNLOCK(bp->b_bufobj);
1826 BO_UNLOCK(bp->b_bufobj);
1829 "getnewbuf(%p) vp %p flags %X kvasize %d bufsize %d "
1830 "queue %d (recycling)", bp, bp->b_vp, bp->b_flags,
1831 bp->b_kvasize, bp->b_bufsize, qindex);
1836 KASSERT(bp->b_qindex == qindex, ("getnewbuf: inconsistant queue %d bp %p", qindex, bp));
1839 * Note: we no longer distinguish between VMIO and non-VMIO
1843 KASSERT((bp->b_flags & B_DELWRI) == 0, ("delwri buffer %p found in queue %d", bp, qindex));
1846 mtx_unlock(&bqlock);
1848 if (qindex == QUEUE_CLEAN) {
1849 if (bp->b_flags & B_VMIO) {
1850 bp->b_flags &= ~B_ASYNC;
1851 vfs_vmio_release(bp);
1858 * NOTE: nbp is now entirely invalid. We can only restart
1859 * the scan from this point on.
1861 * Get the rest of the buffer freed up. b_kva* is still
1862 * valid after this operation.
1865 if (bp->b_rcred != NOCRED) {
1866 crfree(bp->b_rcred);
1867 bp->b_rcred = NOCRED;
1869 if (bp->b_wcred != NOCRED) {
1870 crfree(bp->b_wcred);
1871 bp->b_wcred = NOCRED;
1873 if (!LIST_EMPTY(&bp->b_dep))
1875 if (bp->b_vflags & BV_BKGRDINPROG)
1876 panic("losing buffer 3");
1877 KASSERT(bp->b_vp == NULL,
1878 ("bp: %p still has vnode %p. qindex: %d",
1879 bp, bp->b_vp, qindex));
1880 KASSERT((bp->b_xflags & (BX_VNCLEAN|BX_VNDIRTY)) == 0,
1881 ("bp: %p still on a buffer list. xflags %X",
1892 bp->b_blkno = bp->b_lblkno = 0;
1893 bp->b_offset = NOOFFSET;
1899 bp->b_dirtyoff = bp->b_dirtyend = 0;
1900 bp->b_bufobj = NULL;
1901 bp->b_pin_count = 0;
1902 bp->b_fsprivate1 = NULL;
1903 bp->b_fsprivate2 = NULL;
1904 bp->b_fsprivate3 = NULL;
1906 LIST_INIT(&bp->b_dep);
1909 * If we are defragging then free the buffer.
1912 bp->b_flags |= B_INVAL;
1920 * Notify any waiters for the buffer lock about
1921 * identity change by freeing the buffer.
1923 if (qindex == QUEUE_CLEAN && BUF_LOCKWAITERS(bp) > 0) {
1924 bp->b_flags |= B_INVAL;
1931 * If we are overcomitted then recover the buffer and its
1932 * KVM space. This occurs in rare situations when multiple
1933 * processes are blocked in getnewbuf() or allocbuf().
1935 if (bufspace >= hibufspace)
1937 if (flushingbufs && bp->b_kvasize != 0) {
1938 bp->b_flags |= B_INVAL;
1943 if (bufspace < lobufspace)
1949 * If we exhausted our list, sleep as appropriate. We may have to
1950 * wakeup various daemons and write out some dirty buffers.
1952 * Generally we are sleeping due to insufficient buffer space.
1960 flags = VFS_BIO_NEED_BUFSPACE;
1962 } else if (bufspace >= hibufspace) {
1964 flags = VFS_BIO_NEED_BUFSPACE;
1967 flags = VFS_BIO_NEED_ANY;
1970 needsbuffer |= flags;
1971 mtx_unlock(&nblock);
1972 mtx_unlock(&bqlock);
1974 bd_speedup(); /* heeeelp */
1977 while (needsbuffer & flags) {
1978 if (msleep(&needsbuffer, &nblock,
1979 (PRIBIO + 4) | slpflag, waitmsg, slptimeo)) {
1980 mtx_unlock(&nblock);
1984 mtx_unlock(&nblock);
1987 * We finally have a valid bp. We aren't quite out of the
1988 * woods, we still have to reserve kva space. In order
1989 * to keep fragmentation sane we only allocate kva in
1992 maxsize = (maxsize + BKVAMASK) & ~BKVAMASK;
1994 if (maxsize != bp->b_kvasize) {
1995 vm_offset_t addr = 0;
1999 vm_map_lock(buffer_map);
2000 if (vm_map_findspace(buffer_map,
2001 vm_map_min(buffer_map), maxsize, &addr)) {
2003 * Uh oh. Buffer map is to fragmented. We
2004 * must defragment the map.
2006 atomic_add_int(&bufdefragcnt, 1);
2007 vm_map_unlock(buffer_map);
2009 bp->b_flags |= B_INVAL;
2014 vm_map_insert(buffer_map, NULL, 0,
2015 addr, addr + maxsize,
2016 VM_PROT_ALL, VM_PROT_ALL, MAP_NOFAULT);
2018 bp->b_kvabase = (caddr_t) addr;
2019 bp->b_kvasize = maxsize;
2020 atomic_add_int(&bufspace, bp->b_kvasize);
2021 atomic_add_int(&bufreusecnt, 1);
2023 vm_map_unlock(buffer_map);
2025 bp->b_saveaddr = bp->b_kvabase;
2026 bp->b_data = bp->b_saveaddr;
2034 * buffer flushing daemon. Buffers are normally flushed by the
2035 * update daemon but if it cannot keep up this process starts to
2036 * take the load in an attempt to prevent getnewbuf() from blocking.
2039 static struct kproc_desc buf_kp = {
2044 SYSINIT(bufdaemon, SI_SUB_KTHREAD_BUF, SI_ORDER_FIRST, kproc_start, &buf_kp);
2051 * This process needs to be suspended prior to shutdown sync.
2053 EVENTHANDLER_REGISTER(shutdown_pre_sync, kproc_shutdown, bufdaemonproc,
2057 * This process is allowed to take the buffer cache to the limit
2059 curthread->td_pflags |= TDP_NORUNNINGBUF;
2063 mtx_unlock(&bdlock);
2065 kthread_suspend_check(bufdaemonproc);
2068 * Do the flush. Limit the amount of in-transit I/O we
2069 * allow to build up, otherwise we would completely saturate
2070 * the I/O system. Wakeup any waiting processes before we
2071 * normally would so they can run in parallel with our drain.
2073 while (numdirtybuffers > lodirtybuffers) {
2076 flushed = flushbufqueues(QUEUE_DIRTY, 0);
2077 /* The list empty check here is slightly racy */
2078 if (!TAILQ_EMPTY(&bufqueues[QUEUE_DIRTY_GIANT])) {
2080 flushed += flushbufqueues(QUEUE_DIRTY_GIANT, 0);
2085 * Could not find any buffers without rollback
2086 * dependencies, so just write the first one
2087 * in the hopes of eventually making progress.
2089 flushbufqueues(QUEUE_DIRTY, 1);
2091 &bufqueues[QUEUE_DIRTY_GIANT])) {
2093 flushbufqueues(QUEUE_DIRTY_GIANT, 1);
2102 * Only clear bd_request if we have reached our low water
2103 * mark. The buf_daemon normally waits 1 second and
2104 * then incrementally flushes any dirty buffers that have
2105 * built up, within reason.
2107 * If we were unable to hit our low water mark and couldn't
2108 * find any flushable buffers, we sleep half a second.
2109 * Otherwise we loop immediately.
2112 if (numdirtybuffers <= lodirtybuffers) {
2114 * We reached our low water mark, reset the
2115 * request and sleep until we are needed again.
2116 * The sleep is just so the suspend code works.
2119 msleep(&bd_request, &bdlock, PVM, "psleep", hz);
2122 * We couldn't find any flushable dirty buffers but
2123 * still have too many dirty buffers, we
2124 * have to sleep and try again. (rare)
2126 msleep(&bd_request, &bdlock, PVM, "qsleep", hz / 10);
2134 * Try to flush a buffer in the dirty queue. We must be careful to
2135 * free up B_INVAL buffers instead of write them, which NFS is
2136 * particularly sensitive to.
2138 static int flushwithdeps = 0;
2139 SYSCTL_INT(_vfs, OID_AUTO, flushwithdeps, CTLFLAG_RW, &flushwithdeps,
2140 0, "Number of buffers flushed with dependecies that require rollbacks");
2143 flushbufqueues(int queue, int flushdeps)
2145 struct thread *td = curthread;
2146 struct buf sentinel;
2154 target = numdirtybuffers - lodirtybuffers;
2155 if (flushdeps && target > 2)
2160 TAILQ_INSERT_TAIL(&bufqueues[queue], &sentinel, b_freelist);
2161 while (flushed != target) {
2162 bp = TAILQ_FIRST(&bufqueues[queue]);
2163 if (bp == &sentinel)
2165 TAILQ_REMOVE(&bufqueues[queue], bp, b_freelist);
2166 TAILQ_INSERT_TAIL(&bufqueues[queue], bp, b_freelist);
2168 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0)
2170 if (bp->b_pin_count > 0) {
2174 BO_LOCK(bp->b_bufobj);
2175 if ((bp->b_vflags & BV_BKGRDINPROG) != 0 ||
2176 (bp->b_flags & B_DELWRI) == 0) {
2177 BO_UNLOCK(bp->b_bufobj);
2181 BO_UNLOCK(bp->b_bufobj);
2182 if (bp->b_flags & B_INVAL) {
2184 mtx_unlock(&bqlock);
2187 numdirtywakeup((lodirtybuffers + hidirtybuffers) / 2);
2192 if (!LIST_EMPTY(&bp->b_dep) && buf_countdeps(bp, 0)) {
2193 if (flushdeps == 0) {
2201 * We must hold the lock on a vnode before writing
2202 * one of its buffers. Otherwise we may confuse, or
2203 * in the case of a snapshot vnode, deadlock the
2206 * The lock order here is the reverse of the normal
2207 * of vnode followed by buf lock. This is ok because
2208 * the NOWAIT will prevent deadlock.
2211 if (vn_start_write(vp, &mp, V_NOWAIT) != 0) {
2215 if (vn_lock(vp, LK_EXCLUSIVE | LK_NOWAIT, td) == 0) {
2216 mtx_unlock(&bqlock);
2217 CTR3(KTR_BUF, "flushbufqueue(%p) vp %p flags %X",
2218 bp, bp->b_vp, bp->b_flags);
2220 vn_finished_write(mp);
2221 VOP_UNLOCK(vp, 0, td);
2222 flushwithdeps += hasdeps;
2224 waitrunningbufspace();
2225 numdirtywakeup((lodirtybuffers + hidirtybuffers) / 2);
2229 vn_finished_write(mp);
2232 TAILQ_REMOVE(&bufqueues[queue], &sentinel, b_freelist);
2233 mtx_unlock(&bqlock);
2238 * Check to see if a block is currently memory resident.
2241 incore(struct bufobj *bo, daddr_t blkno)
2246 bp = gbincore(bo, blkno);
2252 * Returns true if no I/O is needed to access the
2253 * associated VM object. This is like incore except
2254 * it also hunts around in the VM system for the data.
2258 inmem(struct vnode * vp, daddr_t blkno)
2261 vm_offset_t toff, tinc, size;
2265 ASSERT_VOP_LOCKED(vp, "inmem");
2267 if (incore(&vp->v_bufobj, blkno))
2269 if (vp->v_mount == NULL)
2276 if (size > vp->v_mount->mnt_stat.f_iosize)
2277 size = vp->v_mount->mnt_stat.f_iosize;
2278 off = (vm_ooffset_t)blkno * (vm_ooffset_t)vp->v_mount->mnt_stat.f_iosize;
2280 VM_OBJECT_LOCK(obj);
2281 for (toff = 0; toff < vp->v_mount->mnt_stat.f_iosize; toff += tinc) {
2282 m = vm_page_lookup(obj, OFF_TO_IDX(off + toff));
2286 if (tinc > PAGE_SIZE - ((toff + off) & PAGE_MASK))
2287 tinc = PAGE_SIZE - ((toff + off) & PAGE_MASK);
2288 if (vm_page_is_valid(m,
2289 (vm_offset_t) ((toff + off) & PAGE_MASK), tinc) == 0)
2292 VM_OBJECT_UNLOCK(obj);
2296 VM_OBJECT_UNLOCK(obj);
2303 * Sets the dirty range for a buffer based on the status of the dirty
2304 * bits in the pages comprising the buffer.
2306 * The range is limited to the size of the buffer.
2308 * This routine is primarily used by NFS, but is generalized for the
2312 vfs_setdirty(struct buf *bp)
2316 * Degenerate case - empty buffer
2319 if (bp->b_bufsize == 0)
2323 * We qualify the scan for modified pages on whether the
2324 * object has been flushed yet.
2327 if ((bp->b_flags & B_VMIO) == 0)
2330 VM_OBJECT_LOCK(bp->b_bufobj->bo_object);
2331 vfs_setdirty_locked_object(bp);
2332 VM_OBJECT_UNLOCK(bp->b_bufobj->bo_object);
2336 vfs_setdirty_locked_object(struct buf *bp)
2341 object = bp->b_bufobj->bo_object;
2342 VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
2343 if (object->flags & (OBJ_MIGHTBEDIRTY|OBJ_CLEANING)) {
2344 vm_offset_t boffset;
2345 vm_offset_t eoffset;
2347 vm_page_lock_queues();
2349 * test the pages to see if they have been modified directly
2350 * by users through the VM system.
2352 for (i = 0; i < bp->b_npages; i++)
2353 vm_page_test_dirty(bp->b_pages[i]);
2356 * Calculate the encompassing dirty range, boffset and eoffset,
2357 * (eoffset - boffset) bytes.
2360 for (i = 0; i < bp->b_npages; i++) {
2361 if (bp->b_pages[i]->dirty)
2364 boffset = (i << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK);
2366 for (i = bp->b_npages - 1; i >= 0; --i) {
2367 if (bp->b_pages[i]->dirty) {
2371 eoffset = ((i + 1) << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK);
2373 vm_page_unlock_queues();
2375 * Fit it to the buffer.
2378 if (eoffset > bp->b_bcount)
2379 eoffset = bp->b_bcount;
2382 * If we have a good dirty range, merge with the existing
2386 if (boffset < eoffset) {
2387 if (bp->b_dirtyoff > boffset)
2388 bp->b_dirtyoff = boffset;
2389 if (bp->b_dirtyend < eoffset)
2390 bp->b_dirtyend = eoffset;
2398 * Get a block given a specified block and offset into a file/device.
2399 * The buffers B_DONE bit will be cleared on return, making it almost
2400 * ready for an I/O initiation. B_INVAL may or may not be set on
2401 * return. The caller should clear B_INVAL prior to initiating a
2404 * For a non-VMIO buffer, B_CACHE is set to the opposite of B_INVAL for
2405 * an existing buffer.
2407 * For a VMIO buffer, B_CACHE is modified according to the backing VM.
2408 * If getblk()ing a previously 0-sized invalid buffer, B_CACHE is set
2409 * and then cleared based on the backing VM. If the previous buffer is
2410 * non-0-sized but invalid, B_CACHE will be cleared.
2412 * If getblk() must create a new buffer, the new buffer is returned with
2413 * both B_INVAL and B_CACHE clear unless it is a VMIO buffer, in which
2414 * case it is returned with B_INVAL clear and B_CACHE set based on the
2417 * getblk() also forces a bwrite() for any B_DELWRI buffer whos
2418 * B_CACHE bit is clear.
2420 * What this means, basically, is that the caller should use B_CACHE to
2421 * determine whether the buffer is fully valid or not and should clear
2422 * B_INVAL prior to issuing a read. If the caller intends to validate
2423 * the buffer by loading its data area with something, the caller needs
2424 * to clear B_INVAL. If the caller does this without issuing an I/O,
2425 * the caller should set B_CACHE ( as an optimization ), else the caller
2426 * should issue the I/O and biodone() will set B_CACHE if the I/O was
2427 * a write attempt or if it was a successfull read. If the caller
2428 * intends to issue a READ, the caller must clear B_INVAL and BIO_ERROR
2429 * prior to issuing the READ. biodone() will *not* clear B_INVAL.
2432 getblk(struct vnode * vp, daddr_t blkno, int size, int slpflag, int slptimeo,
2439 CTR3(KTR_BUF, "getblk(%p, %ld, %d)", vp, (long)blkno, size);
2440 ASSERT_VOP_LOCKED(vp, "getblk");
2441 if (size > MAXBSIZE)
2442 panic("getblk: size(%d) > MAXBSIZE(%d)\n", size, MAXBSIZE);
2447 * Block if we are low on buffers. Certain processes are allowed
2448 * to completely exhaust the buffer cache.
2450 * If this check ever becomes a bottleneck it may be better to
2451 * move it into the else, when gbincore() fails. At the moment
2452 * it isn't a problem.
2454 * XXX remove if 0 sections (clean this up after its proven)
2456 if (numfreebuffers == 0) {
2457 if (TD_IS_IDLETHREAD(curthread))
2460 needsbuffer |= VFS_BIO_NEED_ANY;
2461 mtx_unlock(&nblock);
2465 bp = gbincore(bo, blkno);
2469 * Buffer is in-core. If the buffer is not busy, it must
2472 lockflags = LK_EXCLUSIVE | LK_SLEEPFAIL | LK_INTERLOCK;
2474 if (flags & GB_LOCK_NOWAIT)
2475 lockflags |= LK_NOWAIT;
2477 error = BUF_TIMELOCK(bp, lockflags,
2478 VI_MTX(vp), "getblk", slpflag, slptimeo);
2481 * If we slept and got the lock we have to restart in case
2482 * the buffer changed identities.
2484 if (error == ENOLCK)
2486 /* We timed out or were interrupted. */
2491 * The buffer is locked. B_CACHE is cleared if the buffer is
2492 * invalid. Otherwise, for a non-VMIO buffer, B_CACHE is set
2493 * and for a VMIO buffer B_CACHE is adjusted according to the
2496 if (bp->b_flags & B_INVAL)
2497 bp->b_flags &= ~B_CACHE;
2498 else if ((bp->b_flags & (B_VMIO | B_INVAL)) == 0)
2499 bp->b_flags |= B_CACHE;
2503 * check for size inconsistancies for non-VMIO case.
2506 if (bp->b_bcount != size) {
2507 if ((bp->b_flags & B_VMIO) == 0 ||
2508 (size > bp->b_kvasize)) {
2509 if (bp->b_flags & B_DELWRI) {
2511 * If buffer is pinned and caller does
2512 * not want sleep waiting for it to be
2513 * unpinned, bail out
2515 if (bp->b_pin_count > 0) {
2516 if (flags & GB_LOCK_NOWAIT) {
2523 bp->b_flags |= B_NOCACHE;
2526 if (LIST_EMPTY(&bp->b_dep)) {
2527 bp->b_flags |= B_RELBUF;
2530 bp->b_flags |= B_NOCACHE;
2539 * If the size is inconsistant in the VMIO case, we can resize
2540 * the buffer. This might lead to B_CACHE getting set or
2541 * cleared. If the size has not changed, B_CACHE remains
2542 * unchanged from its previous state.
2545 if (bp->b_bcount != size)
2548 KASSERT(bp->b_offset != NOOFFSET,
2549 ("getblk: no buffer offset"));
2552 * A buffer with B_DELWRI set and B_CACHE clear must
2553 * be committed before we can return the buffer in
2554 * order to prevent the caller from issuing a read
2555 * ( due to B_CACHE not being set ) and overwriting
2558 * Most callers, including NFS and FFS, need this to
2559 * operate properly either because they assume they
2560 * can issue a read if B_CACHE is not set, or because
2561 * ( for example ) an uncached B_DELWRI might loop due
2562 * to softupdates re-dirtying the buffer. In the latter
2563 * case, B_CACHE is set after the first write completes,
2564 * preventing further loops.
2565 * NOTE! b*write() sets B_CACHE. If we cleared B_CACHE
2566 * above while extending the buffer, we cannot allow the
2567 * buffer to remain with B_CACHE set after the write
2568 * completes or it will represent a corrupt state. To
2569 * deal with this we set B_NOCACHE to scrap the buffer
2572 * We might be able to do something fancy, like setting
2573 * B_CACHE in bwrite() except if B_DELWRI is already set,
2574 * so the below call doesn't set B_CACHE, but that gets real
2575 * confusing. This is much easier.
2578 if ((bp->b_flags & (B_CACHE|B_DELWRI)) == B_DELWRI) {
2579 bp->b_flags |= B_NOCACHE;
2583 bp->b_flags &= ~B_DONE;
2585 int bsize, maxsize, vmio;
2589 * Buffer is not in-core, create new buffer. The buffer
2590 * returned by getnewbuf() is locked. Note that the returned
2591 * buffer is also considered valid (not marked B_INVAL).
2595 * If the user does not want us to create the buffer, bail out
2598 if (flags & GB_NOCREAT)
2600 bsize = bo->bo_bsize;
2601 offset = blkno * bsize;
2602 vmio = vp->v_object != NULL;
2603 maxsize = vmio ? size + (offset & PAGE_MASK) : size;
2604 maxsize = imax(maxsize, bsize);
2606 bp = getnewbuf(slpflag, slptimeo, size, maxsize);
2608 if (slpflag || slptimeo)
2614 * This code is used to make sure that a buffer is not
2615 * created while the getnewbuf routine is blocked.
2616 * This can be a problem whether the vnode is locked or not.
2617 * If the buffer is created out from under us, we have to
2618 * throw away the one we just created.
2620 * Note: this must occur before we associate the buffer
2621 * with the vp especially considering limitations in
2622 * the splay tree implementation when dealing with duplicate
2626 if (gbincore(bo, blkno)) {
2628 bp->b_flags |= B_INVAL;
2634 * Insert the buffer into the hash, so that it can
2635 * be found by incore.
2637 bp->b_blkno = bp->b_lblkno = blkno;
2638 bp->b_offset = offset;
2643 * set B_VMIO bit. allocbuf() the buffer bigger. Since the
2644 * buffer size starts out as 0, B_CACHE will be set by
2645 * allocbuf() for the VMIO case prior to it testing the
2646 * backing store for validity.
2650 bp->b_flags |= B_VMIO;
2651 #if defined(VFS_BIO_DEBUG)
2652 if (vn_canvmio(vp) != TRUE)
2653 printf("getblk: VMIO on vnode type %d\n",
2656 KASSERT(vp->v_object == bp->b_bufobj->bo_object,
2657 ("ARGH! different b_bufobj->bo_object %p %p %p\n",
2658 bp, vp->v_object, bp->b_bufobj->bo_object));
2660 bp->b_flags &= ~B_VMIO;
2661 KASSERT(bp->b_bufobj->bo_object == NULL,
2662 ("ARGH! has b_bufobj->bo_object %p %p\n",
2663 bp, bp->b_bufobj->bo_object));
2667 bp->b_flags &= ~B_DONE;
2669 CTR4(KTR_BUF, "getblk(%p, %ld, %d) = %p", vp, (long)blkno, size, bp);
2670 KASSERT(BUF_REFCNT(bp) == 1, ("getblk: bp %p not locked",bp));
2671 KASSERT(bp->b_bufobj == bo,
2672 ("bp %p wrong b_bufobj %p should be %p", bp, bp->b_bufobj, bo));
2677 * Get an empty, disassociated buffer of given size. The buffer is initially
2686 maxsize = (size + BKVAMASK) & ~BKVAMASK;
2687 while ((bp = getnewbuf(0, 0, size, maxsize)) == 0)
2690 bp->b_flags |= B_INVAL; /* b_dep cleared by getnewbuf() */
2691 KASSERT(BUF_REFCNT(bp) == 1, ("geteblk: bp %p not locked",bp));
2697 * This code constitutes the buffer memory from either anonymous system
2698 * memory (in the case of non-VMIO operations) or from an associated
2699 * VM object (in the case of VMIO operations). This code is able to
2700 * resize a buffer up or down.
2702 * Note that this code is tricky, and has many complications to resolve
2703 * deadlock or inconsistant data situations. Tread lightly!!!
2704 * There are B_CACHE and B_DELWRI interactions that must be dealt with by
2705 * the caller. Calling this code willy nilly can result in the loss of data.
2707 * allocbuf() only adjusts B_CACHE for VMIO buffers. getblk() deals with
2708 * B_CACHE for the non-VMIO case.
2712 allocbuf(struct buf *bp, int size)
2714 int newbsize, mbsize;
2717 if (BUF_REFCNT(bp) == 0)
2718 panic("allocbuf: buffer not busy");
2720 if (bp->b_kvasize < size)
2721 panic("allocbuf: buffer too small");
2723 if ((bp->b_flags & B_VMIO) == 0) {
2727 * Just get anonymous memory from the kernel. Don't
2728 * mess with B_CACHE.
2730 mbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1);
2731 if (bp->b_flags & B_MALLOC)
2734 newbsize = round_page(size);
2736 if (newbsize < bp->b_bufsize) {
2738 * malloced buffers are not shrunk
2740 if (bp->b_flags & B_MALLOC) {
2742 bp->b_bcount = size;
2744 free(bp->b_data, M_BIOBUF);
2745 if (bp->b_bufsize) {
2746 atomic_subtract_int(
2752 bp->b_saveaddr = bp->b_kvabase;
2753 bp->b_data = bp->b_saveaddr;
2755 bp->b_flags &= ~B_MALLOC;
2761 (vm_offset_t) bp->b_data + newbsize,
2762 (vm_offset_t) bp->b_data + bp->b_bufsize);
2763 } else if (newbsize > bp->b_bufsize) {
2765 * We only use malloced memory on the first allocation.
2766 * and revert to page-allocated memory when the buffer
2770 * There is a potential smp race here that could lead
2771 * to bufmallocspace slightly passing the max. It
2772 * is probably extremely rare and not worth worrying
2775 if ( (bufmallocspace < maxbufmallocspace) &&
2776 (bp->b_bufsize == 0) &&
2777 (mbsize <= PAGE_SIZE/2)) {
2779 bp->b_data = malloc(mbsize, M_BIOBUF, M_WAITOK);
2780 bp->b_bufsize = mbsize;
2781 bp->b_bcount = size;
2782 bp->b_flags |= B_MALLOC;
2783 atomic_add_int(&bufmallocspace, mbsize);
2789 * If the buffer is growing on its other-than-first allocation,
2790 * then we revert to the page-allocation scheme.
2792 if (bp->b_flags & B_MALLOC) {
2793 origbuf = bp->b_data;
2794 origbufsize = bp->b_bufsize;
2795 bp->b_data = bp->b_kvabase;
2796 if (bp->b_bufsize) {
2797 atomic_subtract_int(&bufmallocspace,
2802 bp->b_flags &= ~B_MALLOC;
2803 newbsize = round_page(newbsize);
2807 (vm_offset_t) bp->b_data + bp->b_bufsize,
2808 (vm_offset_t) bp->b_data + newbsize);
2810 bcopy(origbuf, bp->b_data, origbufsize);
2811 free(origbuf, M_BIOBUF);
2817 newbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1);
2818 desiredpages = (size == 0) ? 0 :
2819 num_pages((bp->b_offset & PAGE_MASK) + newbsize);
2821 if (bp->b_flags & B_MALLOC)
2822 panic("allocbuf: VMIO buffer can't be malloced");
2824 * Set B_CACHE initially if buffer is 0 length or will become
2827 if (size == 0 || bp->b_bufsize == 0)
2828 bp->b_flags |= B_CACHE;
2830 if (newbsize < bp->b_bufsize) {
2832 * DEV_BSIZE aligned new buffer size is less then the
2833 * DEV_BSIZE aligned existing buffer size. Figure out
2834 * if we have to remove any pages.
2836 if (desiredpages < bp->b_npages) {
2839 VM_OBJECT_LOCK(bp->b_bufobj->bo_object);
2840 vm_page_lock_queues();
2841 for (i = desiredpages; i < bp->b_npages; i++) {
2843 * the page is not freed here -- it
2844 * is the responsibility of
2845 * vnode_pager_setsize
2848 KASSERT(m != bogus_page,
2849 ("allocbuf: bogus page found"));
2850 while (vm_page_sleep_if_busy(m, TRUE, "biodep"))
2851 vm_page_lock_queues();
2853 bp->b_pages[i] = NULL;
2854 vm_page_unwire(m, 0);
2856 vm_page_unlock_queues();
2857 VM_OBJECT_UNLOCK(bp->b_bufobj->bo_object);
2858 pmap_qremove((vm_offset_t) trunc_page((vm_offset_t)bp->b_data) +
2859 (desiredpages << PAGE_SHIFT), (bp->b_npages - desiredpages));
2860 bp->b_npages = desiredpages;
2862 } else if (size > bp->b_bcount) {
2864 * We are growing the buffer, possibly in a
2865 * byte-granular fashion.
2873 * Step 1, bring in the VM pages from the object,
2874 * allocating them if necessary. We must clear
2875 * B_CACHE if these pages are not valid for the
2876 * range covered by the buffer.
2880 obj = bp->b_bufobj->bo_object;
2882 VM_OBJECT_LOCK(obj);
2883 while (bp->b_npages < desiredpages) {
2887 pi = OFF_TO_IDX(bp->b_offset) + bp->b_npages;
2888 if ((m = vm_page_lookup(obj, pi)) == NULL) {
2890 * note: must allocate system pages
2891 * since blocking here could intefere
2892 * with paging I/O, no matter which
2895 m = vm_page_alloc(obj, pi,
2896 VM_ALLOC_NOBUSY | VM_ALLOC_SYSTEM |
2899 atomic_add_int(&vm_pageout_deficit,
2900 desiredpages - bp->b_npages);
2901 VM_OBJECT_UNLOCK(obj);
2903 VM_OBJECT_LOCK(obj);
2906 bp->b_flags &= ~B_CACHE;
2907 bp->b_pages[bp->b_npages] = m;
2914 * We found a page. If we have to sleep on it,
2915 * retry because it might have gotten freed out
2918 * We can only test VPO_BUSY here. Blocking on
2919 * m->busy might lead to a deadlock:
2921 * vm_fault->getpages->cluster_read->allocbuf
2924 if (vm_page_sleep_if_busy(m, FALSE, "pgtblk"))
2928 * We have a good page.
2930 vm_page_lock_queues();
2932 vm_page_unlock_queues();
2933 bp->b_pages[bp->b_npages] = m;
2938 * Step 2. We've loaded the pages into the buffer,
2939 * we have to figure out if we can still have B_CACHE
2940 * set. Note that B_CACHE is set according to the
2941 * byte-granular range ( bcount and size ), new the
2942 * aligned range ( newbsize ).
2944 * The VM test is against m->valid, which is DEV_BSIZE
2945 * aligned. Needless to say, the validity of the data
2946 * needs to also be DEV_BSIZE aligned. Note that this
2947 * fails with NFS if the server or some other client
2948 * extends the file's EOF. If our buffer is resized,
2949 * B_CACHE may remain set! XXX
2952 toff = bp->b_bcount;
2953 tinc = PAGE_SIZE - ((bp->b_offset + toff) & PAGE_MASK);
2955 while ((bp->b_flags & B_CACHE) && toff < size) {
2958 if (tinc > (size - toff))
2961 pi = ((bp->b_offset & PAGE_MASK) + toff) >>
2974 VM_OBJECT_UNLOCK(obj);
2977 * Step 3, fixup the KVM pmap. Remember that
2978 * bp->b_data is relative to bp->b_offset, but
2979 * bp->b_offset may be offset into the first page.
2982 bp->b_data = (caddr_t)
2983 trunc_page((vm_offset_t)bp->b_data);
2985 (vm_offset_t)bp->b_data,
2990 bp->b_data = (caddr_t)((vm_offset_t)bp->b_data |
2991 (vm_offset_t)(bp->b_offset & PAGE_MASK));
2994 if (newbsize < bp->b_bufsize)
2996 bp->b_bufsize = newbsize; /* actual buffer allocation */
2997 bp->b_bcount = size; /* requested buffer size */
3002 biodone(struct bio *bp)
3004 void (*done)(struct bio *);
3006 mtx_lock(&bdonelock);
3007 bp->bio_flags |= BIO_DONE;
3008 done = bp->bio_done;
3011 mtx_unlock(&bdonelock);
3017 * Wait for a BIO to finish.
3019 * XXX: resort to a timeout for now. The optimal locking (if any) for this
3020 * case is not yet clear.
3023 biowait(struct bio *bp, const char *wchan)
3026 mtx_lock(&bdonelock);
3027 while ((bp->bio_flags & BIO_DONE) == 0)
3028 msleep(bp, &bdonelock, PRIBIO, wchan, hz / 10);
3029 mtx_unlock(&bdonelock);
3030 if (bp->bio_error != 0)
3031 return (bp->bio_error);
3032 if (!(bp->bio_flags & BIO_ERROR))
3038 biofinish(struct bio *bp, struct devstat *stat, int error)
3042 bp->bio_error = error;
3043 bp->bio_flags |= BIO_ERROR;
3046 devstat_end_transaction_bio(stat, bp);
3053 * Wait for buffer I/O completion, returning error status. The buffer
3054 * is left locked and B_DONE on return. B_EINTR is converted into an EINTR
3055 * error and cleared.
3058 bufwait(struct buf *bp)
3060 if (bp->b_iocmd == BIO_READ)
3061 bwait(bp, PRIBIO, "biord");
3063 bwait(bp, PRIBIO, "biowr");
3064 if (bp->b_flags & B_EINTR) {
3065 bp->b_flags &= ~B_EINTR;
3068 if (bp->b_ioflags & BIO_ERROR) {
3069 return (bp->b_error ? bp->b_error : EIO);
3076 * Call back function from struct bio back up to struct buf.
3079 bufdonebio(struct bio *bip)
3083 bp = bip->bio_caller2;
3084 bp->b_resid = bp->b_bcount - bip->bio_completed;
3085 bp->b_resid = bip->bio_resid; /* XXX: remove */
3086 bp->b_ioflags = bip->bio_flags;
3087 bp->b_error = bip->bio_error;
3089 bp->b_ioflags |= BIO_ERROR;
3095 dev_strategy(struct cdev *dev, struct buf *bp)
3100 if ((!bp->b_iocmd) || (bp->b_iocmd & (bp->b_iocmd - 1)))
3101 panic("b_iocmd botch");
3106 /* Try again later */
3107 tsleep(&bp, PRIBIO, "dev_strat", hz/10);
3109 bip->bio_cmd = bp->b_iocmd;
3110 bip->bio_offset = bp->b_iooffset;
3111 bip->bio_length = bp->b_bcount;
3112 bip->bio_bcount = bp->b_bcount; /* XXX: remove */
3113 bip->bio_data = bp->b_data;
3114 bip->bio_done = bufdonebio;
3115 bip->bio_caller2 = bp;
3117 KASSERT(dev->si_refcount > 0,
3118 ("dev_strategy on un-referenced struct cdev *(%s)",
3120 csw = dev_refthread(dev);
3123 bp->b_error = ENXIO;
3124 bp->b_ioflags = BIO_ERROR;
3128 (*csw->d_strategy)(bip);
3135 * Finish I/O on a buffer, optionally calling a completion function.
3136 * This is usually called from an interrupt so process blocking is
3139 * biodone is also responsible for setting B_CACHE in a B_VMIO bp.
3140 * In a non-VMIO bp, B_CACHE will be set on the next getblk()
3141 * assuming B_INVAL is clear.
3143 * For the VMIO case, we set B_CACHE if the op was a read and no
3144 * read error occured, or if the op was a write. B_CACHE is never
3145 * set if the buffer is invalid or otherwise uncacheable.
3147 * biodone does not mess with B_INVAL, allowing the I/O routine or the
3148 * initiator to leave B_INVAL set to brelse the buffer out of existance
3149 * in the biodone routine.
3152 bufdone(struct buf *bp)
3154 struct bufobj *dropobj;
3155 void (*biodone)(struct buf *);
3157 CTR3(KTR_BUF, "bufdone(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
3160 KASSERT(BUF_REFCNT(bp) > 0, ("biodone: bp %p not busy %d", bp,
3162 KASSERT(!(bp->b_flags & B_DONE), ("biodone: bp %p already done", bp));
3164 runningbufwakeup(bp);
3165 if (bp->b_iocmd == BIO_WRITE)
3166 dropobj = bp->b_bufobj;
3167 /* call optional completion function if requested */
3168 if (bp->b_iodone != NULL) {
3169 biodone = bp->b_iodone;
3170 bp->b_iodone = NULL;
3173 bufobj_wdrop(dropobj);
3180 bufobj_wdrop(dropobj);
3184 bufdone_finish(struct buf *bp)
3186 KASSERT(BUF_REFCNT(bp) > 0, ("biodone: bp %p not busy %d", bp,
3189 if (!LIST_EMPTY(&bp->b_dep))
3192 if (bp->b_flags & B_VMIO) {
3198 struct vnode *vp = bp->b_vp;
3199 boolean_t are_queues_locked;
3201 obj = bp->b_bufobj->bo_object;
3203 #if defined(VFS_BIO_DEBUG)
3204 mp_fixme("usecount and vflag accessed without locks.");
3205 if (vp->v_usecount == 0) {
3206 panic("biodone: zero vnode ref count");
3209 KASSERT(vp->v_object != NULL,
3210 ("biodone: vnode %p has no vm_object", vp));
3213 foff = bp->b_offset;
3214 KASSERT(bp->b_offset != NOOFFSET,
3215 ("biodone: no buffer offset"));
3217 VM_OBJECT_LOCK(obj);
3218 #if defined(VFS_BIO_DEBUG)
3219 if (obj->paging_in_progress < bp->b_npages) {
3220 printf("biodone: paging in progress(%d) < bp->b_npages(%d)\n",
3221 obj->paging_in_progress, bp->b_npages);
3226 * Set B_CACHE if the op was a normal read and no error
3227 * occured. B_CACHE is set for writes in the b*write()
3230 iosize = bp->b_bcount - bp->b_resid;
3231 if (bp->b_iocmd == BIO_READ &&
3232 !(bp->b_flags & (B_INVAL|B_NOCACHE)) &&
3233 !(bp->b_ioflags & BIO_ERROR)) {
3234 bp->b_flags |= B_CACHE;
3236 if (bp->b_iocmd == BIO_READ) {
3237 vm_page_lock_queues();
3238 are_queues_locked = TRUE;
3240 are_queues_locked = FALSE;
3241 for (i = 0; i < bp->b_npages; i++) {
3245 resid = ((foff + PAGE_SIZE) & ~(off_t)PAGE_MASK) - foff;
3250 * cleanup bogus pages, restoring the originals
3253 if (m == bogus_page) {
3255 m = vm_page_lookup(obj, OFF_TO_IDX(foff));
3257 panic("biodone: page disappeared!");
3259 pmap_qenter(trunc_page((vm_offset_t)bp->b_data),
3260 bp->b_pages, bp->b_npages);
3262 #if defined(VFS_BIO_DEBUG)
3263 if (OFF_TO_IDX(foff) != m->pindex) {
3265 "biodone: foff(%jd)/m->pindex(%ju) mismatch\n",
3266 (intmax_t)foff, (uintmax_t)m->pindex);
3271 * In the write case, the valid and clean bits are
3272 * already changed correctly ( see bdwrite() ), so we
3273 * only need to do this here in the read case.
3275 if ((bp->b_iocmd == BIO_READ) && !bogusflag && resid > 0) {
3276 vfs_page_set_valid(bp, foff, i, m);
3280 * when debugging new filesystems or buffer I/O methods, this
3281 * is the most common error that pops up. if you see this, you
3282 * have not set the page busy flag correctly!!!
3285 printf("biodone: page busy < 0, "
3286 "pindex: %d, foff: 0x(%x,%x), "
3287 "resid: %d, index: %d\n",
3288 (int) m->pindex, (int)(foff >> 32),
3289 (int) foff & 0xffffffff, resid, i);
3290 if (!vn_isdisk(vp, NULL))
3291 printf(" iosize: %jd, lblkno: %jd, flags: 0x%x, npages: %d\n",
3292 (intmax_t)bp->b_vp->v_mount->mnt_stat.f_iosize,
3293 (intmax_t) bp->b_lblkno,
3294 bp->b_flags, bp->b_npages);
3296 printf(" VDEV, lblkno: %jd, flags: 0x%x, npages: %d\n",
3297 (intmax_t) bp->b_lblkno,
3298 bp->b_flags, bp->b_npages);
3299 printf(" valid: 0x%lx, dirty: 0x%lx, wired: %d\n",
3300 (u_long)m->valid, (u_long)m->dirty,
3302 panic("biodone: page busy < 0\n");
3304 vm_page_io_finish(m);
3305 vm_object_pip_subtract(obj, 1);
3306 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK;
3309 if (are_queues_locked)
3310 vm_page_unlock_queues();
3311 vm_object_pip_wakeupn(obj, 0);
3312 VM_OBJECT_UNLOCK(obj);
3316 * For asynchronous completions, release the buffer now. The brelse
3317 * will do a wakeup there if necessary - so no need to do a wakeup
3318 * here in the async case. The sync case always needs to do a wakeup.
3321 if (bp->b_flags & B_ASYNC) {
3322 if ((bp->b_flags & (B_NOCACHE | B_INVAL | B_RELBUF)) || (bp->b_ioflags & BIO_ERROR))
3331 * This routine is called in lieu of iodone in the case of
3332 * incomplete I/O. This keeps the busy status for pages
3336 vfs_unbusy_pages(struct buf *bp)
3342 runningbufwakeup(bp);
3343 if (!(bp->b_flags & B_VMIO))
3346 obj = bp->b_bufobj->bo_object;
3347 VM_OBJECT_LOCK(obj);
3348 for (i = 0; i < bp->b_npages; i++) {
3350 if (m == bogus_page) {
3351 m = vm_page_lookup(obj, OFF_TO_IDX(bp->b_offset) + i);
3353 panic("vfs_unbusy_pages: page missing\n");
3355 pmap_qenter(trunc_page((vm_offset_t)bp->b_data),
3356 bp->b_pages, bp->b_npages);
3358 vm_object_pip_subtract(obj, 1);
3359 vm_page_io_finish(m);
3361 vm_object_pip_wakeupn(obj, 0);
3362 VM_OBJECT_UNLOCK(obj);
3366 * vfs_page_set_valid:
3368 * Set the valid bits in a page based on the supplied offset. The
3369 * range is restricted to the buffer's size.
3371 * This routine is typically called after a read completes.
3374 vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, int pageno, vm_page_t m)
3376 vm_ooffset_t soff, eoff;
3378 mtx_assert(&vm_page_queue_mtx, MA_OWNED);
3380 * Start and end offsets in buffer. eoff - soff may not cross a
3381 * page boundry or cross the end of the buffer. The end of the
3382 * buffer, in this case, is our file EOF, not the allocation size
3386 eoff = (off + PAGE_SIZE) & ~(off_t)PAGE_MASK;
3387 if (eoff > bp->b_offset + bp->b_bcount)
3388 eoff = bp->b_offset + bp->b_bcount;
3391 * Set valid range. This is typically the entire buffer and thus the
3395 vm_page_set_validclean(
3397 (vm_offset_t) (soff & PAGE_MASK),
3398 (vm_offset_t) (eoff - soff)
3404 * This routine is called before a device strategy routine.
3405 * It is used to tell the VM system that paging I/O is in
3406 * progress, and treat the pages associated with the buffer
3407 * almost as being VPO_BUSY. Also the object paging_in_progress
3408 * flag is handled to make sure that the object doesn't become
3411 * Since I/O has not been initiated yet, certain buffer flags
3412 * such as BIO_ERROR or B_INVAL may be in an inconsistant state
3413 * and should be ignored.
3416 vfs_busy_pages(struct buf *bp, int clear_modify)
3423 if (!(bp->b_flags & B_VMIO))
3426 obj = bp->b_bufobj->bo_object;
3427 foff = bp->b_offset;
3428 KASSERT(bp->b_offset != NOOFFSET,
3429 ("vfs_busy_pages: no buffer offset"));
3430 VM_OBJECT_LOCK(obj);
3431 if (bp->b_bufsize != 0)
3432 vfs_setdirty_locked_object(bp);
3434 for (i = 0; i < bp->b_npages; i++) {
3437 if (vm_page_sleep_if_busy(m, FALSE, "vbpage"))
3441 vm_page_lock_queues();
3442 for (i = 0; i < bp->b_npages; i++) {
3445 if ((bp->b_flags & B_CLUSTER) == 0) {
3446 vm_object_pip_add(obj, 1);
3447 vm_page_io_start(m);
3450 * When readying a buffer for a read ( i.e
3451 * clear_modify == 0 ), it is important to do
3452 * bogus_page replacement for valid pages in
3453 * partially instantiated buffers. Partially
3454 * instantiated buffers can, in turn, occur when
3455 * reconstituting a buffer from its VM backing store
3456 * base. We only have to do this if B_CACHE is
3457 * clear ( which causes the I/O to occur in the
3458 * first place ). The replacement prevents the read
3459 * I/O from overwriting potentially dirty VM-backed
3460 * pages. XXX bogus page replacement is, uh, bogus.
3461 * It may not work properly with small-block devices.
3462 * We need to find a better way.
3466 vfs_page_set_valid(bp, foff, i, m);
3467 else if (m->valid == VM_PAGE_BITS_ALL &&
3468 (bp->b_flags & B_CACHE) == 0) {
3469 bp->b_pages[i] = bogus_page;
3472 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK;
3474 vm_page_unlock_queues();
3475 VM_OBJECT_UNLOCK(obj);
3477 pmap_qenter(trunc_page((vm_offset_t)bp->b_data),
3478 bp->b_pages, bp->b_npages);
3482 * Tell the VM system that the pages associated with this buffer
3483 * are clean. This is used for delayed writes where the data is
3484 * going to go to disk eventually without additional VM intevention.
3486 * Note that while we only really need to clean through to b_bcount, we
3487 * just go ahead and clean through to b_bufsize.
3490 vfs_clean_pages(struct buf *bp)
3493 vm_ooffset_t foff, noff, eoff;
3496 if (!(bp->b_flags & B_VMIO))
3499 foff = bp->b_offset;
3500 KASSERT(bp->b_offset != NOOFFSET,
3501 ("vfs_clean_pages: no buffer offset"));
3502 VM_OBJECT_LOCK(bp->b_bufobj->bo_object);
3503 vm_page_lock_queues();
3504 for (i = 0; i < bp->b_npages; i++) {
3506 noff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK;
3509 if (eoff > bp->b_offset + bp->b_bufsize)
3510 eoff = bp->b_offset + bp->b_bufsize;
3511 vfs_page_set_valid(bp, foff, i, m);
3512 /* vm_page_clear_dirty(m, foff & PAGE_MASK, eoff - foff); */
3515 vm_page_unlock_queues();
3516 VM_OBJECT_UNLOCK(bp->b_bufobj->bo_object);
3520 * vfs_bio_set_validclean:
3522 * Set the range within the buffer to valid and clean. The range is
3523 * relative to the beginning of the buffer, b_offset. Note that b_offset
3524 * itself may be offset from the beginning of the first page.
3529 vfs_bio_set_validclean(struct buf *bp, int base, int size)
3534 if (!(bp->b_flags & B_VMIO))
3537 * Fixup base to be relative to beginning of first page.
3538 * Set initial n to be the maximum number of bytes in the
3539 * first page that can be validated.
3542 base += (bp->b_offset & PAGE_MASK);
3543 n = PAGE_SIZE - (base & PAGE_MASK);
3545 VM_OBJECT_LOCK(bp->b_bufobj->bo_object);
3546 vm_page_lock_queues();
3547 for (i = base / PAGE_SIZE; size > 0 && i < bp->b_npages; ++i) {
3551 vm_page_set_validclean(m, base & PAGE_MASK, n);
3556 vm_page_unlock_queues();
3557 VM_OBJECT_UNLOCK(bp->b_bufobj->bo_object);
3563 * clear a buffer. This routine essentially fakes an I/O, so we need
3564 * to clear BIO_ERROR and B_INVAL.
3566 * Note that while we only theoretically need to clear through b_bcount,
3567 * we go ahead and clear through b_bufsize.
3571 vfs_bio_clrbuf(struct buf *bp)
3576 if ((bp->b_flags & (B_VMIO | B_MALLOC)) != B_VMIO) {
3581 bp->b_flags &= ~B_INVAL;
3582 bp->b_ioflags &= ~BIO_ERROR;
3583 VM_OBJECT_LOCK(bp->b_bufobj->bo_object);
3584 if ((bp->b_npages == 1) && (bp->b_bufsize < PAGE_SIZE) &&
3585 (bp->b_offset & PAGE_MASK) == 0) {
3586 if (bp->b_pages[0] == bogus_page)
3588 mask = (1 << (bp->b_bufsize / DEV_BSIZE)) - 1;
3589 VM_OBJECT_LOCK_ASSERT(bp->b_pages[0]->object, MA_OWNED);
3590 if ((bp->b_pages[0]->valid & mask) == mask)
3592 if (((bp->b_pages[0]->flags & PG_ZERO) == 0) &&
3593 ((bp->b_pages[0]->valid & mask) == 0)) {
3594 bzero(bp->b_data, bp->b_bufsize);
3595 bp->b_pages[0]->valid |= mask;
3599 ea = sa = bp->b_data;
3600 for(i = 0; i < bp->b_npages; i++, sa = ea) {
3601 ea = (caddr_t)trunc_page((vm_offset_t)sa + PAGE_SIZE);
3602 ea = (caddr_t)(vm_offset_t)ulmin(
3603 (u_long)(vm_offset_t)ea,
3604 (u_long)(vm_offset_t)bp->b_data + bp->b_bufsize);
3605 if (bp->b_pages[i] == bogus_page)
3607 j = ((vm_offset_t)sa & PAGE_MASK) / DEV_BSIZE;
3608 mask = ((1 << ((ea - sa) / DEV_BSIZE)) - 1) << j;
3609 VM_OBJECT_LOCK_ASSERT(bp->b_pages[i]->object, MA_OWNED);
3610 if ((bp->b_pages[i]->valid & mask) == mask)
3612 if ((bp->b_pages[i]->valid & mask) == 0) {
3613 if ((bp->b_pages[i]->flags & PG_ZERO) == 0)
3616 for (; sa < ea; sa += DEV_BSIZE, j++) {
3617 if (((bp->b_pages[i]->flags & PG_ZERO) == 0) &&
3618 (bp->b_pages[i]->valid & (1 << j)) == 0)
3619 bzero(sa, DEV_BSIZE);
3622 bp->b_pages[i]->valid |= mask;
3625 VM_OBJECT_UNLOCK(bp->b_bufobj->bo_object);
3630 * vm_hold_load_pages and vm_hold_free_pages get pages into
3631 * a buffers address space. The pages are anonymous and are
3632 * not associated with a file object.
3635 vm_hold_load_pages(struct buf *bp, vm_offset_t from, vm_offset_t to)
3641 to = round_page(to);
3642 from = round_page(from);
3643 index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT;
3645 VM_OBJECT_LOCK(kernel_object);
3646 for (pg = from; pg < to; pg += PAGE_SIZE, index++) {
3649 * note: must allocate system pages since blocking here
3650 * could intefere with paging I/O, no matter which
3653 p = vm_page_alloc(kernel_object,
3654 ((pg - VM_MIN_KERNEL_ADDRESS) >> PAGE_SHIFT),
3655 VM_ALLOC_NOBUSY | VM_ALLOC_SYSTEM | VM_ALLOC_WIRED);
3657 atomic_add_int(&vm_pageout_deficit,
3658 (to - pg) >> PAGE_SHIFT);
3659 VM_OBJECT_UNLOCK(kernel_object);
3661 VM_OBJECT_LOCK(kernel_object);
3664 p->valid = VM_PAGE_BITS_ALL;
3665 pmap_qenter(pg, &p, 1);
3666 bp->b_pages[index] = p;
3668 VM_OBJECT_UNLOCK(kernel_object);
3669 bp->b_npages = index;
3672 /* Return pages associated with this buf to the vm system */
3674 vm_hold_free_pages(struct buf *bp, vm_offset_t from, vm_offset_t to)
3678 int index, newnpages;
3680 from = round_page(from);
3681 to = round_page(to);
3682 newnpages = index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT;
3684 VM_OBJECT_LOCK(kernel_object);
3685 for (pg = from; pg < to; pg += PAGE_SIZE, index++) {
3686 p = bp->b_pages[index];
3687 if (p && (index < bp->b_npages)) {
3690 "vm_hold_free_pages: blkno: %jd, lblkno: %jd\n",
3691 (intmax_t)bp->b_blkno,
3692 (intmax_t)bp->b_lblkno);
3694 bp->b_pages[index] = NULL;
3695 pmap_qremove(pg, 1);
3696 vm_page_lock_queues();
3697 vm_page_unwire(p, 0);
3699 vm_page_unlock_queues();
3702 VM_OBJECT_UNLOCK(kernel_object);
3703 bp->b_npages = newnpages;
3707 * Map an IO request into kernel virtual address space.
3709 * All requests are (re)mapped into kernel VA space.
3710 * Notice that we use b_bufsize for the size of the buffer
3711 * to be mapped. b_bcount might be modified by the driver.
3713 * Note that even if the caller determines that the address space should
3714 * be valid, a race or a smaller-file mapped into a larger space may
3715 * actually cause vmapbuf() to fail, so all callers of vmapbuf() MUST
3716 * check the return value.
3719 vmapbuf(struct buf *bp)
3725 struct pmap *pmap = &curproc->p_vmspace->vm_pmap;
3727 if (bp->b_bufsize < 0)
3729 prot = VM_PROT_READ;
3730 if (bp->b_iocmd == BIO_READ)
3731 prot |= VM_PROT_WRITE; /* Less backwards than it looks */
3732 for (addr = (caddr_t)trunc_page((vm_offset_t)bp->b_data), pidx = 0;
3733 addr < bp->b_data + bp->b_bufsize;
3734 addr += PAGE_SIZE, pidx++) {
3736 * Do the vm_fault if needed; do the copy-on-write thing
3737 * when reading stuff off device into memory.
3739 * NOTE! Must use pmap_extract() because addr may be in
3740 * the userland address space, and kextract is only guarenteed
3741 * to work for the kernland address space (see: sparc64 port).
3744 if (vm_fault_quick(addr >= bp->b_data ? addr : bp->b_data,
3746 vm_page_lock_queues();
3747 for (i = 0; i < pidx; ++i) {
3748 vm_page_unhold(bp->b_pages[i]);
3749 bp->b_pages[i] = NULL;
3751 vm_page_unlock_queues();
3754 m = pmap_extract_and_hold(pmap, (vm_offset_t)addr, prot);
3757 bp->b_pages[pidx] = m;
3759 if (pidx > btoc(MAXPHYS))
3760 panic("vmapbuf: mapped more than MAXPHYS");
3761 pmap_qenter((vm_offset_t)bp->b_saveaddr, bp->b_pages, pidx);
3763 kva = bp->b_saveaddr;
3764 bp->b_npages = pidx;
3765 bp->b_saveaddr = bp->b_data;
3766 bp->b_data = kva + (((vm_offset_t) bp->b_data) & PAGE_MASK);
3771 * Free the io map PTEs associated with this IO operation.
3772 * We also invalidate the TLB entries and restore the original b_addr.
3775 vunmapbuf(struct buf *bp)
3780 npages = bp->b_npages;
3781 pmap_qremove(trunc_page((vm_offset_t)bp->b_data), npages);
3782 vm_page_lock_queues();
3783 for (pidx = 0; pidx < npages; pidx++)
3784 vm_page_unhold(bp->b_pages[pidx]);
3785 vm_page_unlock_queues();
3787 bp->b_data = bp->b_saveaddr;
3791 bdone(struct buf *bp)
3794 mtx_lock(&bdonelock);
3795 bp->b_flags |= B_DONE;
3797 mtx_unlock(&bdonelock);
3801 bwait(struct buf *bp, u_char pri, const char *wchan)
3804 mtx_lock(&bdonelock);
3805 while ((bp->b_flags & B_DONE) == 0)
3806 msleep(bp, &bdonelock, pri, wchan, 0);
3807 mtx_unlock(&bdonelock);
3811 bufsync(struct bufobj *bo, int waitfor, struct thread *td)
3814 return (VOP_FSYNC(bo->__bo_vnode, waitfor, td));
3818 bufstrategy(struct bufobj *bo, struct buf *bp)
3824 KASSERT(vp == bo->bo_private, ("Inconsistent vnode bufstrategy"));
3825 KASSERT(vp->v_type != VCHR && vp->v_type != VBLK,
3826 ("Wrong vnode in bufstrategy(bp=%p, vp=%p)", bp, vp));
3827 i = VOP_STRATEGY(vp, bp);
3828 KASSERT(i == 0, ("VOP_STRATEGY failed bp=%p vp=%p", bp, bp->b_vp));
3832 bufobj_wrefl(struct bufobj *bo)
3835 KASSERT(bo != NULL, ("NULL bo in bufobj_wref"));
3836 ASSERT_BO_LOCKED(bo);
3841 bufobj_wref(struct bufobj *bo)
3844 KASSERT(bo != NULL, ("NULL bo in bufobj_wref"));
3851 bufobj_wdrop(struct bufobj *bo)
3854 KASSERT(bo != NULL, ("NULL bo in bufobj_wdrop"));
3856 KASSERT(bo->bo_numoutput > 0, ("bufobj_wdrop non-positive count"));
3857 if ((--bo->bo_numoutput == 0) && (bo->bo_flag & BO_WWAIT)) {
3858 bo->bo_flag &= ~BO_WWAIT;
3859 wakeup(&bo->bo_numoutput);
3865 bufobj_wwait(struct bufobj *bo, int slpflag, int timeo)
3869 KASSERT(bo != NULL, ("NULL bo in bufobj_wwait"));
3870 ASSERT_BO_LOCKED(bo);
3872 while (bo->bo_numoutput) {
3873 bo->bo_flag |= BO_WWAIT;
3874 error = msleep(&bo->bo_numoutput, BO_MTX(bo),
3875 slpflag | (PRIBIO + 1), "bo_wwait", timeo);
3883 bpin(struct buf *bp)
3885 mtx_lock(&bpinlock);
3887 mtx_unlock(&bpinlock);
3891 bunpin(struct buf *bp)
3893 mtx_lock(&bpinlock);
3894 if (--bp->b_pin_count == 0)
3896 mtx_unlock(&bpinlock);
3900 bunpin_wait(struct buf *bp)
3902 mtx_lock(&bpinlock);
3903 while (bp->b_pin_count > 0)
3904 msleep(bp, &bpinlock, PRIBIO, "bwunpin", 0);
3905 mtx_unlock(&bpinlock);
3908 #include "opt_ddb.h"
3910 #include <ddb/ddb.h>
3912 /* DDB command to show buffer data */
3913 DB_SHOW_COMMAND(buffer, db_show_buffer)
3916 struct buf *bp = (struct buf *)addr;
3919 db_printf("usage: show buffer <addr>\n");
3923 db_printf("buf at %p\n", bp);
3924 db_printf("b_flags = 0x%b\n", (u_int)bp->b_flags, PRINT_BUF_FLAGS);
3926 "b_error = %d, b_bufsize = %ld, b_bcount = %ld, b_resid = %ld\n"
3927 "b_bufobj = (%p), b_data = %p, b_blkno = %jd, b_dep = %p\n",
3928 bp->b_error, bp->b_bufsize, bp->b_bcount, bp->b_resid,
3929 bp->b_bufobj, bp->b_data, (intmax_t)bp->b_blkno,
3930 bp->b_dep.lh_first);
3933 db_printf("b_npages = %d, pages(OBJ, IDX, PA): ", bp->b_npages);
3934 for (i = 0; i < bp->b_npages; i++) {
3937 db_printf("(%p, 0x%lx, 0x%lx)", (void *)m->object,
3938 (u_long)m->pindex, (u_long)VM_PAGE_TO_PHYS(m));
3939 if ((i + 1) < bp->b_npages)
3944 lockmgr_printinfo(&bp->b_lock);
3947 DB_SHOW_COMMAND(lockedbufs, lockedbufs)
3952 for (i = 0; i < nbuf; i++) {
3954 if (lockcount(&bp->b_lock)) {
3955 db_show_buffer((uintptr_t)bp, 1, 0, NULL);
3961 DB_SHOW_COMMAND(vnodebufs, db_show_vnodebufs)
3967 db_printf("usage: show vnodebufs <addr>\n");
3970 vp = (struct vnode *)addr;
3971 db_printf("Clean buffers:\n");
3972 TAILQ_FOREACH(bp, &vp->v_bufobj.bo_clean.bv_hd, b_bobufs) {
3973 db_show_buffer((uintptr_t)bp, 1, 0, NULL);
3976 db_printf("Dirty buffers:\n");
3977 TAILQ_FOREACH(bp, &vp->v_bufobj.bo_dirty.bv_hd, b_bobufs) {
3978 db_show_buffer((uintptr_t)bp, 1, 0, NULL);