2 * Copyright (c) 1994,1997 John S. Dyson
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
8 * 1. Redistributions of source code must retain the above copyright
9 * notice immediately at the beginning of the file, without modification,
10 * this list of conditions, and the following disclaimer.
11 * 2. Absolutely no warranty of function or purpose is made by the author
16 * this file contains a new buffer I/O scheme implementing a coherent
17 * VM object and buffer cache scheme. Pains have been taken to make
18 * sure that the performance degradation associated with schemes such
19 * as this is not realized.
21 * Author: John S. Dyson
22 * Significant help during the development and debugging phases
23 * had been provided by David Greenman, also of the FreeBSD core team.
25 * see man buf(9) for more info.
28 #include <sys/cdefs.h>
29 __FBSDID("$FreeBSD$");
31 #include <sys/param.h>
32 #include <sys/systm.h>
36 #include <sys/devicestat.h>
37 #include <sys/eventhandler.h>
39 #include <sys/malloc.h>
40 #include <sys/mount.h>
41 #include <sys/mutex.h>
42 #include <sys/kernel.h>
43 #include <sys/kthread.h>
45 #include <sys/resourcevar.h>
46 #include <sys/sysctl.h>
47 #include <sys/vmmeter.h>
48 #include <sys/vnode.h>
50 #include <vm/vm_param.h>
51 #include <vm/vm_kern.h>
52 #include <vm/vm_pageout.h>
53 #include <vm/vm_page.h>
54 #include <vm/vm_object.h>
55 #include <vm/vm_extern.h>
56 #include <vm/vm_map.h>
57 #include "opt_directio.h"
60 static MALLOC_DEFINE(M_BIOBUF, "BIO buffer", "BIO buffer");
62 struct bio_ops bioops; /* I/O operation notification */
64 static int ibwrite(struct buf *);
66 struct buf_ops buf_ops_bio = {
72 * XXX buf is global because kern_shutdown.c and ffs_checkoverlap has
73 * carnal knowledge of buffers. This knowledge should be moved to vfs_bio.c.
75 struct buf *buf; /* buffer header pool */
77 static struct proc *bufdaemonproc;
79 static void vm_hold_free_pages(struct buf *bp, vm_offset_t from,
81 static void vm_hold_load_pages(struct buf *bp, vm_offset_t from,
83 static void vfs_page_set_valid(struct buf *bp, vm_ooffset_t off,
84 int pageno, vm_page_t m);
85 static void vfs_clean_pages(struct buf *bp);
86 static void vfs_setdirty(struct buf *bp);
87 static void vfs_vmio_release(struct buf *bp);
88 static void vfs_backgroundwritedone(struct buf *bp);
89 static int vfs_bio_clcheck(struct vnode *vp, int size,
90 daddr_t lblkno, daddr_t blkno);
91 static int flushbufqueues(int flushdeps);
92 static void buf_daemon(void);
93 void bremfreel(struct buf *bp);
95 int vmiodirenable = TRUE;
96 SYSCTL_INT(_vfs, OID_AUTO, vmiodirenable, CTLFLAG_RW, &vmiodirenable, 0,
97 "Use the VM system for directory writes");
99 SYSCTL_INT(_vfs, OID_AUTO, runningbufspace, CTLFLAG_RD, &runningbufspace, 0,
100 "Amount of presently outstanding async buffer io");
102 SYSCTL_INT(_vfs, OID_AUTO, bufspace, CTLFLAG_RD, &bufspace, 0,
103 "KVA memory used for bufs");
104 static int maxbufspace;
105 SYSCTL_INT(_vfs, OID_AUTO, maxbufspace, CTLFLAG_RD, &maxbufspace, 0,
106 "Maximum allowed value of bufspace (including buf_daemon)");
107 static int bufmallocspace;
108 SYSCTL_INT(_vfs, OID_AUTO, bufmallocspace, CTLFLAG_RD, &bufmallocspace, 0,
109 "Amount of malloced memory for buffers");
110 static int maxbufmallocspace;
111 SYSCTL_INT(_vfs, OID_AUTO, maxmallocbufspace, CTLFLAG_RW, &maxbufmallocspace, 0,
112 "Maximum amount of malloced memory for buffers");
113 static int lobufspace;
114 SYSCTL_INT(_vfs, OID_AUTO, lobufspace, CTLFLAG_RD, &lobufspace, 0,
115 "Minimum amount of buffers we want to have");
116 static int hibufspace;
117 SYSCTL_INT(_vfs, OID_AUTO, hibufspace, CTLFLAG_RD, &hibufspace, 0,
118 "Maximum allowed value of bufspace (excluding buf_daemon)");
119 static int bufreusecnt;
120 SYSCTL_INT(_vfs, OID_AUTO, bufreusecnt, CTLFLAG_RW, &bufreusecnt, 0,
121 "Number of times we have reused a buffer");
122 static int buffreekvacnt;
123 SYSCTL_INT(_vfs, OID_AUTO, buffreekvacnt, CTLFLAG_RW, &buffreekvacnt, 0,
124 "Number of times we have freed the KVA space from some buffer");
125 static int bufdefragcnt;
126 SYSCTL_INT(_vfs, OID_AUTO, bufdefragcnt, CTLFLAG_RW, &bufdefragcnt, 0,
127 "Number of times we have had to repeat buffer allocation to defragment");
128 static int lorunningspace;
129 SYSCTL_INT(_vfs, OID_AUTO, lorunningspace, CTLFLAG_RW, &lorunningspace, 0,
130 "Minimum preferred space used for in-progress I/O");
131 static int hirunningspace;
132 SYSCTL_INT(_vfs, OID_AUTO, hirunningspace, CTLFLAG_RW, &hirunningspace, 0,
133 "Maximum amount of space to use for in-progress I/O");
134 static int dirtybufferflushes;
135 SYSCTL_INT(_vfs, OID_AUTO, dirtybufferflushes, CTLFLAG_RW, &dirtybufferflushes,
136 0, "Number of bdwrite to bawrite conversions to limit dirty buffers");
137 static int altbufferflushes;
138 SYSCTL_INT(_vfs, OID_AUTO, altbufferflushes, CTLFLAG_RW, &altbufferflushes,
139 0, "Number of fsync flushes to limit dirty buffers");
140 static int recursiveflushes;
141 SYSCTL_INT(_vfs, OID_AUTO, recursiveflushes, CTLFLAG_RW, &recursiveflushes,
142 0, "Number of flushes skipped due to being recursive");
143 static int numdirtybuffers;
144 SYSCTL_INT(_vfs, OID_AUTO, numdirtybuffers, CTLFLAG_RD, &numdirtybuffers, 0,
145 "Number of buffers that are dirty (has unwritten changes) at the moment");
146 static int lodirtybuffers;
147 SYSCTL_INT(_vfs, OID_AUTO, lodirtybuffers, CTLFLAG_RW, &lodirtybuffers, 0,
148 "How many buffers we want to have free before bufdaemon can sleep");
149 static int hidirtybuffers;
150 SYSCTL_INT(_vfs, OID_AUTO, hidirtybuffers, CTLFLAG_RW, &hidirtybuffers, 0,
151 "When the number of dirty buffers is considered severe");
152 static int dirtybufthresh;
153 SYSCTL_INT(_vfs, OID_AUTO, dirtybufthresh, CTLFLAG_RW, &dirtybufthresh,
154 0, "Number of bdwrite to bawrite conversions to clear dirty buffers");
155 static int numfreebuffers;
156 SYSCTL_INT(_vfs, OID_AUTO, numfreebuffers, CTLFLAG_RD, &numfreebuffers, 0,
157 "Number of free buffers");
158 static int lofreebuffers;
159 SYSCTL_INT(_vfs, OID_AUTO, lofreebuffers, CTLFLAG_RW, &lofreebuffers, 0,
161 static int hifreebuffers;
162 SYSCTL_INT(_vfs, OID_AUTO, hifreebuffers, CTLFLAG_RW, &hifreebuffers, 0,
163 "XXX Complicatedly unused");
164 static int getnewbufcalls;
165 SYSCTL_INT(_vfs, OID_AUTO, getnewbufcalls, CTLFLAG_RW, &getnewbufcalls, 0,
166 "Number of calls to getnewbuf");
167 static int getnewbufrestarts;
168 SYSCTL_INT(_vfs, OID_AUTO, getnewbufrestarts, CTLFLAG_RW, &getnewbufrestarts, 0,
169 "Number of times getnewbuf has had to restart a buffer aquisition");
170 static int dobkgrdwrite = 1;
171 SYSCTL_INT(_debug, OID_AUTO, dobkgrdwrite, CTLFLAG_RW, &dobkgrdwrite, 0,
172 "Do background writes (honoring the BV_BKGRDWRITE flag)?");
175 * Wakeup point for bufdaemon, as well as indicator of whether it is already
176 * active. Set to 1 when the bufdaemon is already "on" the queue, 0 when it
179 static int bd_request;
182 * This lock synchronizes access to bd_request.
184 static struct mtx bdlock;
187 * bogus page -- for I/O to/from partially complete buffers
188 * this is a temporary solution to the problem, but it is not
189 * really that bad. it would be better to split the buffer
190 * for input in the case of buffers partially already in memory,
191 * but the code is intricate enough already.
193 vm_page_t bogus_page;
196 * Synchronization (sleep/wakeup) variable for active buffer space requests.
197 * Set when wait starts, cleared prior to wakeup().
198 * Used in runningbufwakeup() and waitrunningbufspace().
200 static int runningbufreq;
203 * This lock protects the runningbufreq and synchronizes runningbufwakeup and
204 * waitrunningbufspace().
206 static struct mtx rbreqlock;
209 * Synchronization (sleep/wakeup) variable for buffer requests.
210 * Can contain the VFS_BIO_NEED flags defined below; setting/clearing is done
212 * Used in numdirtywakeup(), bufspacewakeup(), bufcountwakeup(), bwillwrite(),
213 * getnewbuf(), and getblk().
215 static int needsbuffer;
218 * Lock that protects needsbuffer and the sleeps/wakeups surrounding it.
220 static struct mtx nblock;
223 * Lock that protects against bwait()/bdone()/B_DONE races.
226 static struct mtx bdonelock;
229 * Definitions for the buffer free lists.
231 #define BUFFER_QUEUES 5 /* number of free buffer queues */
233 #define QUEUE_NONE 0 /* on no queue */
234 #define QUEUE_CLEAN 1 /* non-B_DELWRI buffers */
235 #define QUEUE_DIRTY 2 /* B_DELWRI buffers */
236 #define QUEUE_EMPTYKVA 3 /* empty buffer headers w/KVA assignment */
237 #define QUEUE_EMPTY 4 /* empty buffer headers */
239 /* Queues for free buffers with various properties */
240 static TAILQ_HEAD(bqueues, buf) bufqueues[BUFFER_QUEUES] = { { 0 } };
242 /* Lock for the bufqueues */
243 static struct mtx bqlock;
246 * Single global constant for BUF_WMESG, to avoid getting multiple references.
247 * buf_wmesg is referred from macros.
249 const char *buf_wmesg = BUF_WMESG;
251 #define VFS_BIO_NEED_ANY 0x01 /* any freeable buffer */
252 #define VFS_BIO_NEED_DIRTYFLUSH 0x02 /* waiting for dirty buffer flush */
253 #define VFS_BIO_NEED_FREE 0x04 /* wait for free bufs, hi hysteresis */
254 #define VFS_BIO_NEED_BUFSPACE 0x08 /* wait for buf space, lo hysteresis */
257 extern void ffs_rawread_setup(void);
258 #endif /* DIRECTIO */
262 * If someone is blocked due to there being too many dirty buffers,
263 * and numdirtybuffers is now reasonable, wake them up.
267 numdirtywakeup(int level)
270 if (numdirtybuffers <= level) {
272 if (needsbuffer & VFS_BIO_NEED_DIRTYFLUSH) {
273 needsbuffer &= ~VFS_BIO_NEED_DIRTYFLUSH;
274 wakeup(&needsbuffer);
283 * Called when buffer space is potentially available for recovery.
284 * getnewbuf() will block on this flag when it is unable to free
285 * sufficient buffer space. Buffer space becomes recoverable when
286 * bp's get placed back in the queues.
294 * If someone is waiting for BUF space, wake them up. Even
295 * though we haven't freed the kva space yet, the waiting
296 * process will be able to now.
299 if (needsbuffer & VFS_BIO_NEED_BUFSPACE) {
300 needsbuffer &= ~VFS_BIO_NEED_BUFSPACE;
301 wakeup(&needsbuffer);
307 * runningbufwakeup() - in-progress I/O accounting.
311 runningbufwakeup(struct buf *bp)
314 if (bp->b_runningbufspace) {
315 atomic_subtract_int(&runningbufspace, bp->b_runningbufspace);
316 bp->b_runningbufspace = 0;
317 mtx_lock(&rbreqlock);
318 if (runningbufreq && runningbufspace <= lorunningspace) {
320 wakeup(&runningbufreq);
322 mtx_unlock(&rbreqlock);
329 * Called when a buffer has been added to one of the free queues to
330 * account for the buffer and to wakeup anyone waiting for free buffers.
331 * This typically occurs when large amounts of metadata are being handled
332 * by the buffer cache ( else buffer space runs out first, usually ).
339 atomic_add_int(&numfreebuffers, 1);
342 needsbuffer &= ~VFS_BIO_NEED_ANY;
343 if (numfreebuffers >= hifreebuffers)
344 needsbuffer &= ~VFS_BIO_NEED_FREE;
345 wakeup(&needsbuffer);
351 * waitrunningbufspace()
353 * runningbufspace is a measure of the amount of I/O currently
354 * running. This routine is used in async-write situations to
355 * prevent creating huge backups of pending writes to a device.
356 * Only asynchronous writes are governed by this function.
358 * Reads will adjust runningbufspace, but will not block based on it.
359 * The read load has a side effect of reducing the allowed write load.
361 * This does NOT turn an async write into a sync write. It waits
362 * for earlier writes to complete and generally returns before the
363 * caller's write has reached the device.
366 waitrunningbufspace(void)
369 mtx_lock(&rbreqlock);
370 while (runningbufspace > hirunningspace) {
372 msleep(&runningbufreq, &rbreqlock, PVM, "wdrain", 0);
374 mtx_unlock(&rbreqlock);
379 * vfs_buf_test_cache:
381 * Called when a buffer is extended. This function clears the B_CACHE
382 * bit if the newly extended portion of the buffer does not contain
387 vfs_buf_test_cache(struct buf *bp,
388 vm_ooffset_t foff, vm_offset_t off, vm_offset_t size,
394 VM_OBJECT_LOCK_ASSERT(m->object, MA_OWNED);
395 if (bp->b_flags & B_CACHE) {
396 int base = (foff + off) & PAGE_MASK;
397 if (vm_page_is_valid(m, base, size) == 0)
398 bp->b_flags &= ~B_CACHE;
402 /* Wake up the buffer deamon if necessary */
405 bd_wakeup(int dirtybuflevel)
409 if (bd_request == 0 && numdirtybuffers >= dirtybuflevel) {
417 * bd_speedup - speedup the buffer cache flushing code
429 * Calculating buffer cache scaling values and reserve space for buffer
430 * headers. This is called during low level kernel initialization and
431 * may be called more then once. We CANNOT write to the memory area
432 * being reserved at this time.
435 kern_vfs_bio_buffer_alloc(caddr_t v, long physmem_est)
439 * physmem_est is in pages. Convert it to kilobytes (assumes
440 * PAGE_SIZE is >= 1K)
442 physmem_est = physmem_est * (PAGE_SIZE / 1024);
445 * The nominal buffer size (and minimum KVA allocation) is BKVASIZE.
446 * For the first 64MB of ram nominally allocate sufficient buffers to
447 * cover 1/4 of our ram. Beyond the first 64MB allocate additional
448 * buffers to cover 1/20 of our ram over 64MB. When auto-sizing
449 * the buffer cache we limit the eventual kva reservation to
452 * factor represents the 1/4 x ram conversion.
455 int factor = 4 * BKVASIZE / 1024;
458 if (physmem_est > 4096)
459 nbuf += min((physmem_est - 4096) / factor,
461 if (physmem_est > 65536)
462 nbuf += (physmem_est - 65536) * 2 / (factor * 5);
464 if (maxbcache && nbuf > maxbcache / BKVASIZE)
465 nbuf = maxbcache / BKVASIZE;
470 * Do not allow the buffer_map to be more then 1/2 the size of the
473 if (nbuf > (kernel_map->max_offset - kernel_map->min_offset) /
475 nbuf = (kernel_map->max_offset - kernel_map->min_offset) /
477 printf("Warning: nbufs capped at %d\n", nbuf);
482 * swbufs are used as temporary holders for I/O, such as paging I/O.
483 * We have no less then 16 and no more then 256.
485 nswbuf = max(min(nbuf/4, 256), 16);
487 if (nswbuf < NSWBUF_MIN)
495 * Reserve space for the buffer cache buffers
498 v = (caddr_t)(swbuf + nswbuf);
500 v = (caddr_t)(buf + nbuf);
505 /* Initialize the buffer subsystem. Called before use of any buffers. */
514 mtx_init(&bqlock, "buf queue lock", NULL, MTX_DEF);
515 mtx_init(&rbreqlock, "runningbufspace lock", NULL, MTX_DEF);
516 mtx_init(&nblock, "needsbuffer lock", NULL, MTX_DEF);
517 mtx_init(&bdlock, "buffer daemon lock", NULL, MTX_DEF);
518 mtx_init(&bdonelock, "bdone lock", NULL, MTX_DEF);
520 /* next, make a null set of free lists */
521 for (i = 0; i < BUFFER_QUEUES; i++)
522 TAILQ_INIT(&bufqueues[i]);
524 /* finally, initialize each buffer header and stick on empty q */
525 for (i = 0; i < nbuf; i++) {
527 bzero(bp, sizeof *bp);
528 bp->b_flags = B_INVAL; /* we're just an empty header */
530 bp->b_rcred = NOCRED;
531 bp->b_wcred = NOCRED;
532 bp->b_qindex = QUEUE_EMPTY;
535 LIST_INIT(&bp->b_dep);
537 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_EMPTY], bp, b_freelist);
541 * maxbufspace is the absolute maximum amount of buffer space we are
542 * allowed to reserve in KVM and in real terms. The absolute maximum
543 * is nominally used by buf_daemon. hibufspace is the nominal maximum
544 * used by most other processes. The differential is required to
545 * ensure that buf_daemon is able to run when other processes might
546 * be blocked waiting for buffer space.
548 * maxbufspace is based on BKVASIZE. Allocating buffers larger then
549 * this may result in KVM fragmentation which is not handled optimally
552 maxbufspace = nbuf * BKVASIZE;
553 hibufspace = imax(3 * maxbufspace / 4, maxbufspace - MAXBSIZE * 10);
554 lobufspace = hibufspace - MAXBSIZE;
556 lorunningspace = 512 * 1024;
557 hirunningspace = 1024 * 1024;
560 * Limit the amount of malloc memory since it is wired permanently into
561 * the kernel space. Even though this is accounted for in the buffer
562 * allocation, we don't want the malloced region to grow uncontrolled.
563 * The malloc scheme improves memory utilization significantly on average
564 * (small) directories.
566 maxbufmallocspace = hibufspace / 20;
569 * Reduce the chance of a deadlock occuring by limiting the number
570 * of delayed-write dirty buffers we allow to stack up.
572 hidirtybuffers = nbuf / 4 + 20;
573 dirtybufthresh = hidirtybuffers * 9 / 10;
576 * To support extreme low-memory systems, make sure hidirtybuffers cannot
577 * eat up all available buffer space. This occurs when our minimum cannot
578 * be met. We try to size hidirtybuffers to 3/4 our buffer space assuming
579 * BKVASIZE'd (8K) buffers.
581 while (hidirtybuffers * BKVASIZE > 3 * hibufspace / 4) {
582 hidirtybuffers >>= 1;
584 lodirtybuffers = hidirtybuffers / 2;
587 * Try to keep the number of free buffers in the specified range,
588 * and give special processes (e.g. like buf_daemon) access to an
591 lofreebuffers = nbuf / 18 + 5;
592 hifreebuffers = 2 * lofreebuffers;
593 numfreebuffers = nbuf;
596 * Maximum number of async ops initiated per buf_daemon loop. This is
597 * somewhat of a hack at the moment, we really need to limit ourselves
598 * based on the number of bytes of I/O in-transit that were initiated
602 bogus_page = vm_page_alloc(NULL, 0, VM_ALLOC_NOOBJ |
603 VM_ALLOC_NORMAL | VM_ALLOC_WIRED);
607 * bfreekva() - free the kva allocation for a buffer.
609 * Must be called at splbio() or higher as this is the only locking for
612 * Since this call frees up buffer space, we call bufspacewakeup().
615 bfreekva(struct buf *bp)
621 atomic_add_int(&buffreekvacnt, 1);
622 atomic_subtract_int(&bufspace, bp->b_kvasize);
623 vm_map_delete(buffer_map,
624 (vm_offset_t) bp->b_kvabase,
625 (vm_offset_t) bp->b_kvabase + bp->b_kvasize
635 * Remove the buffer from the appropriate free list.
638 bremfree(struct buf *bp)
647 bremfreel(struct buf *bp)
650 int old_qindex = bp->b_qindex;
654 if (bp->b_qindex != QUEUE_NONE) {
655 KASSERT(BUF_REFCNT(bp) == 1, ("bremfree: bp %p not locked",bp));
656 TAILQ_REMOVE(&bufqueues[bp->b_qindex], bp, b_freelist);
657 bp->b_qindex = QUEUE_NONE;
659 if (BUF_REFCNT(bp) <= 1)
660 panic("bremfree: removing a buffer not on a queue");
664 * Fixup numfreebuffers count. If the buffer is invalid or not
665 * delayed-write, and it was on the EMPTY, LRU, or AGE queues,
666 * the buffer was free and we must decrement numfreebuffers.
668 if ((bp->b_flags & B_INVAL) || (bp->b_flags & B_DELWRI) == 0) {
674 atomic_subtract_int(&numfreebuffers, 1);
685 * Get a buffer with the specified data. Look in the cache first. We
686 * must clear BIO_ERROR and B_INVAL prior to initiating I/O. If B_CACHE
687 * is set, the buffer is valid and we do not have to do anything ( see
688 * getblk() ). This is really just a special case of breadn().
691 bread(struct vnode * vp, daddr_t blkno, int size, struct ucred * cred,
695 return (breadn(vp, blkno, size, 0, 0, 0, cred, bpp));
699 * Operates like bread, but also starts asynchronous I/O on
700 * read-ahead blocks. We must clear BIO_ERROR and B_INVAL prior
701 * to initiating I/O . If B_CACHE is set, the buffer is valid
702 * and we do not have to do anything.
705 breadn(struct vnode * vp, daddr_t blkno, int size,
706 daddr_t * rablkno, int *rabsize,
707 int cnt, struct ucred * cred, struct buf **bpp)
709 struct buf *bp, *rabp;
711 int rv = 0, readwait = 0;
713 *bpp = bp = getblk(vp, blkno, size, 0, 0, 0);
715 /* if not found in cache, do some I/O */
716 if ((bp->b_flags & B_CACHE) == 0) {
717 if (curthread != PCPU_GET(idlethread))
718 curthread->td_proc->p_stats->p_ru.ru_inblock++;
719 bp->b_iocmd = BIO_READ;
720 bp->b_flags &= ~B_INVAL;
721 bp->b_ioflags &= ~BIO_ERROR;
722 if (bp->b_rcred == NOCRED && cred != NOCRED)
723 bp->b_rcred = crhold(cred);
724 vfs_busy_pages(bp, 0);
725 bp->b_iooffset = dbtob(bp->b_blkno);
726 if (vp->v_type == VCHR)
727 VOP_SPECSTRATEGY(vp, bp);
729 VOP_STRATEGY(vp, bp);
733 for (i = 0; i < cnt; i++, rablkno++, rabsize++) {
734 if (inmem(vp, *rablkno))
736 rabp = getblk(vp, *rablkno, *rabsize, 0, 0, 0);
738 if ((rabp->b_flags & B_CACHE) == 0) {
739 if (curthread != PCPU_GET(idlethread))
740 curthread->td_proc->p_stats->p_ru.ru_inblock++;
741 rabp->b_flags |= B_ASYNC;
742 rabp->b_flags &= ~B_INVAL;
743 rabp->b_ioflags &= ~BIO_ERROR;
744 rabp->b_iocmd = BIO_READ;
745 if (rabp->b_rcred == NOCRED && cred != NOCRED)
746 rabp->b_rcred = crhold(cred);
747 vfs_busy_pages(rabp, 0);
749 rabp->b_iooffset = dbtob(rabp->b_blkno);
750 if (vp->v_type == VCHR)
751 VOP_SPECSTRATEGY(vp, rabp);
753 VOP_STRATEGY(vp, rabp);
766 * Write, release buffer on completion. (Done by iodone
767 * if async). Do not bother writing anything if the buffer
770 * Note that we set B_CACHE here, indicating that buffer is
771 * fully valid and thus cacheable. This is true even of NFS
772 * now so we set it generally. This could be set either here
773 * or in biodone() since the I/O is synchronous. We put it
777 bwrite(struct buf *bp)
780 KASSERT(bp->b_op != NULL && bp->b_op->bop_write != NULL,
781 ("Martian buffer %p in bwrite: nobody to write it.", bp));
782 return (bp->b_op->bop_write(bp));
786 ibwrite(struct buf *bp)
791 if (bp->b_flags & B_INVAL) {
796 oldflags = bp->b_flags;
798 if (BUF_REFCNT(bp) == 0)
799 panic("ibwrite: buffer is not busy???");
802 * If a background write is already in progress, delay
803 * writing this block if it is asynchronous. Otherwise
804 * wait for the background write to complete.
807 if (bp->b_vflags & BV_BKGRDINPROG) {
808 if (bp->b_flags & B_ASYNC) {
814 bp->b_vflags |= BV_BKGRDWAIT;
815 msleep(&bp->b_xflags, VI_MTX(bp->b_vp), PRIBIO, "bwrbg", 0);
816 if (bp->b_vflags & BV_BKGRDINPROG)
817 panic("ibwrite: still writing");
821 /* Mark the buffer clean */
825 * If this buffer is marked for background writing and we
826 * do not have to wait for it, make a copy and write the
827 * copy so as to leave this buffer ready for further use.
829 * This optimization eats a lot of memory. If we have a page
830 * or buffer shortfall we can't do it.
832 if (dobkgrdwrite && (bp->b_xflags & BX_BKGRDWRITE) &&
833 (bp->b_flags & B_ASYNC) &&
834 !vm_page_count_severe() &&
835 !buf_dirty_count_severe()) {
836 if (bp->b_iodone != NULL) {
837 printf("bp->b_iodone = %p\n", bp->b_iodone);
838 panic("ibwrite: need chained iodone");
841 /* get a new block */
842 newbp = geteblk(bp->b_bufsize);
845 * set it to be identical to the old block. We have to
846 * set b_lblkno and BKGRDMARKER before calling bgetvp()
847 * to avoid confusing the splay tree and gbincore().
849 memcpy(newbp->b_data, bp->b_data, bp->b_bufsize);
850 newbp->b_lblkno = bp->b_lblkno;
851 newbp->b_xflags |= BX_BKGRDMARKER;
853 bp->b_vflags |= BV_BKGRDINPROG;
854 bgetvp(bp->b_vp, newbp);
856 newbp->b_blkno = bp->b_blkno;
857 newbp->b_offset = bp->b_offset;
858 newbp->b_iodone = vfs_backgroundwritedone;
859 newbp->b_flags |= B_ASYNC;
860 newbp->b_flags &= ~B_INVAL;
862 /* move over the dependencies */
863 if (LIST_FIRST(&bp->b_dep) != NULL)
864 buf_movedeps(bp, newbp);
867 * Initiate write on the copy, release the original to
868 * the B_LOCKED queue so that it cannot go away until
869 * the background write completes. If not locked it could go
870 * away and then be reconstituted while it was being written.
871 * If the reconstituted buffer were written, we could end up
872 * with two background copies being written at the same time.
878 bp->b_flags &= ~B_DONE;
879 bp->b_ioflags &= ~BIO_ERROR;
880 bp->b_flags |= B_CACHE;
881 bp->b_iocmd = BIO_WRITE;
883 bufobj_wref(&bp->b_vp->v_bufobj);
884 vfs_busy_pages(bp, 1);
887 * Normal bwrites pipeline writes
889 bp->b_runningbufspace = bp->b_bufsize;
890 atomic_add_int(&runningbufspace, bp->b_runningbufspace);
892 if (curthread != PCPU_GET(idlethread))
893 curthread->td_proc->p_stats->p_ru.ru_oublock++;
895 if (oldflags & B_ASYNC)
897 bp->b_iooffset = dbtob(bp->b_blkno);
898 if (bp->b_vp->v_type == VCHR) {
899 if (!buf_prewrite(bp->b_vp, bp))
900 VOP_SPECSTRATEGY(bp->b_vp, bp);
902 VOP_STRATEGY(bp->b_vp, bp);
905 if ((oldflags & B_ASYNC) == 0) {
906 int rtval = bufwait(bp);
911 * don't allow the async write to saturate the I/O
912 * system. We will not deadlock here because
913 * we are blocking waiting for I/O that is already in-progress
914 * to complete. We do not block here if it is the update
915 * or syncer daemon trying to clean up as that can lead
918 if (curthread->td_proc != bufdaemonproc &&
919 curthread->td_proc != updateproc)
920 waitrunningbufspace();
927 * Complete a background write started from bwrite.
930 vfs_backgroundwritedone(struct buf *bp)
935 * Find the original buffer that we are writing.
938 if ((origbp = gbincore(bp->b_vp, bp->b_lblkno)) == NULL)
939 panic("backgroundwritedone: lost buffer");
942 * Clear the BV_BKGRDINPROG flag in the original buffer
943 * and awaken it if it is waiting for the write to complete.
944 * If BV_BKGRDINPROG is not set in the original buffer it must
945 * have been released and re-instantiated - which is not legal.
947 KASSERT((origbp->b_vflags & BV_BKGRDINPROG),
948 ("backgroundwritedone: lost buffer2"));
949 origbp->b_vflags &= ~BV_BKGRDINPROG;
950 if (origbp->b_vflags & BV_BKGRDWAIT) {
951 origbp->b_vflags &= ~BV_BKGRDWAIT;
952 wakeup(&origbp->b_xflags);
956 * Process dependencies then return any unfinished ones.
958 if (LIST_FIRST(&bp->b_dep) != NULL)
960 if (LIST_FIRST(&bp->b_dep) != NULL)
961 buf_movedeps(bp, origbp);
964 * This buffer is marked B_NOCACHE, so when it is released
965 * by biodone, it will be tossed. We mark it with BIO_READ
966 * to avoid biodone doing a second bufobj_wakeup.
968 bp->b_flags |= B_NOCACHE;
969 bp->b_iocmd = BIO_READ;
970 bp->b_flags &= ~(B_CACHE | B_DONE);
976 * Delayed write. (Buffer is marked dirty). Do not bother writing
977 * anything if the buffer is marked invalid.
979 * Note that since the buffer must be completely valid, we can safely
980 * set B_CACHE. In fact, we have to set B_CACHE here rather then in
981 * biodone() in order to prevent getblk from writing the buffer
985 bdwrite(struct buf *bp)
987 struct thread *td = curthread;
993 if (BUF_REFCNT(bp) == 0)
994 panic("bdwrite: buffer is not busy");
996 if (bp->b_flags & B_INVAL) {
1002 * If we have too many dirty buffers, don't create any more.
1003 * If we are wildly over our limit, then force a complete
1004 * cleanup. Otherwise, just keep the situation from getting
1005 * out of control. Note that we have to avoid a recursive
1006 * disaster and not try to clean up after our own cleanup!
1010 if (td->td_pflags & TDP_COWINPROGRESS) {
1012 } else if (vp != NULL && vp->v_dirtybufcnt > dirtybufthresh + 10) {
1014 (void) VOP_FSYNC(vp, td->td_ucred, MNT_NOWAIT, td);
1017 } else if (vp != NULL && vp->v_dirtybufcnt > dirtybufthresh) {
1019 * Try to find a buffer to flush.
1021 TAILQ_FOREACH(nbp, &vp->v_dirtyblkhd, b_bobufs) {
1022 if ((nbp->b_vflags & BV_BKGRDINPROG) ||
1023 buf_countdeps(nbp, 0) ||
1024 BUF_LOCK(nbp, LK_EXCLUSIVE | LK_NOWAIT, NULL))
1027 panic("bdwrite: found ourselves");
1029 if (nbp->b_flags & B_CLUSTEROK) {
1030 vfs_bio_awrite(nbp);
1036 dirtybufferflushes++;
1044 * Set B_CACHE, indicating that the buffer is fully valid. This is
1045 * true even of NFS now.
1047 bp->b_flags |= B_CACHE;
1050 * This bmap keeps the system from needing to do the bmap later,
1051 * perhaps when the system is attempting to do a sync. Since it
1052 * is likely that the indirect block -- or whatever other datastructure
1053 * that the filesystem needs is still in memory now, it is a good
1054 * thing to do this. Note also, that if the pageout daemon is
1055 * requesting a sync -- there might not be enough memory to do
1056 * the bmap then... So, this is important to do.
1058 if (vp->v_type != VCHR && bp->b_lblkno == bp->b_blkno) {
1059 VOP_BMAP(vp, bp->b_lblkno, NULL, &bp->b_blkno, NULL, NULL);
1063 * Set the *dirty* buffer range based upon the VM system dirty pages.
1068 * We need to do this here to satisfy the vnode_pager and the
1069 * pageout daemon, so that it thinks that the pages have been
1070 * "cleaned". Note that since the pages are in a delayed write
1071 * buffer -- the VFS layer "will" see that the pages get written
1072 * out on the next sync, or perhaps the cluster will be completed.
1074 vfs_clean_pages(bp);
1078 * Wakeup the buffer flushing daemon if we have a lot of dirty
1079 * buffers (midpoint between our recovery point and our stall
1082 bd_wakeup((lodirtybuffers + hidirtybuffers) / 2);
1085 * note: we cannot initiate I/O from a bdwrite even if we wanted to,
1086 * due to the softdep code.
1093 * Turn buffer into delayed write request. We must clear BIO_READ and
1094 * B_RELBUF, and we must set B_DELWRI. We reassign the buffer to
1095 * itself to properly update it in the dirty/clean lists. We mark it
1096 * B_DONE to ensure that any asynchronization of the buffer properly
1097 * clears B_DONE ( else a panic will occur later ).
1099 * bdirty() is kinda like bdwrite() - we have to clear B_INVAL which
1100 * might have been set pre-getblk(). Unlike bwrite/bdwrite, bdirty()
1101 * should only be called if the buffer is known-good.
1103 * Since the buffer is not on a queue, we do not update the numfreebuffers
1106 * Must be called at splbio().
1107 * The buffer must be on QUEUE_NONE.
1110 bdirty(struct buf *bp)
1113 KASSERT(bp->b_qindex == QUEUE_NONE,
1114 ("bdirty: buffer %p still on queue %d", bp, bp->b_qindex));
1115 bp->b_flags &= ~(B_RELBUF);
1116 bp->b_iocmd = BIO_WRITE;
1118 if ((bp->b_flags & B_DELWRI) == 0) {
1119 bp->b_flags |= B_DONE | B_DELWRI;
1121 atomic_add_int(&numdirtybuffers, 1);
1122 bd_wakeup((lodirtybuffers + hidirtybuffers) / 2);
1129 * Clear B_DELWRI for buffer.
1131 * Since the buffer is not on a queue, we do not update the numfreebuffers
1134 * Must be called at splbio().
1135 * The buffer must be on QUEUE_NONE.
1139 bundirty(struct buf *bp)
1142 KASSERT(bp->b_qindex == QUEUE_NONE,
1143 ("bundirty: buffer %p still on queue %d", bp, bp->b_qindex));
1145 if (bp->b_flags & B_DELWRI) {
1146 bp->b_flags &= ~B_DELWRI;
1148 atomic_subtract_int(&numdirtybuffers, 1);
1149 numdirtywakeup(lodirtybuffers);
1152 * Since it is now being written, we can clear its deferred write flag.
1154 bp->b_flags &= ~B_DEFERRED;
1160 * Asynchronous write. Start output on a buffer, but do not wait for
1161 * it to complete. The buffer is released when the output completes.
1163 * bwrite() ( or the VOP routine anyway ) is responsible for handling
1164 * B_INVAL buffers. Not us.
1167 bawrite(struct buf *bp)
1170 bp->b_flags |= B_ASYNC;
1177 * Called prior to the locking of any vnodes when we are expecting to
1178 * write. We do not want to starve the buffer cache with too many
1179 * dirty buffers so we block here. By blocking prior to the locking
1180 * of any vnodes we attempt to avoid the situation where a locked vnode
1181 * prevents the various system daemons from flushing related buffers.
1188 if (numdirtybuffers >= hidirtybuffers) {
1194 while (numdirtybuffers >= hidirtybuffers) {
1196 needsbuffer |= VFS_BIO_NEED_DIRTYFLUSH;
1197 msleep(&needsbuffer, &nblock,
1198 (PRIBIO + 4), "flswai", 0);
1201 mtx_unlock(&nblock);
1207 * Return true if we have too many dirty buffers.
1210 buf_dirty_count_severe(void)
1213 return(numdirtybuffers >= hidirtybuffers);
1219 * Release a busy buffer and, if requested, free its resources. The
1220 * buffer will be stashed in the appropriate bufqueue[] allowing it
1221 * to be accessed later as a cache entity or reused for other purposes.
1224 brelse(struct buf *bp)
1230 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)),
1231 ("brelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp));
1235 if (bp->b_iocmd == BIO_WRITE &&
1236 (bp->b_ioflags & BIO_ERROR) &&
1237 !(bp->b_flags & B_INVAL)) {
1239 * Failed write, redirty. Must clear BIO_ERROR to prevent
1240 * pages from being scrapped. If B_INVAL is set then
1241 * this case is not run and the next case is run to
1242 * destroy the buffer. B_INVAL can occur if the buffer
1243 * is outside the range supported by the underlying device.
1245 bp->b_ioflags &= ~BIO_ERROR;
1247 } else if ((bp->b_flags & (B_NOCACHE | B_INVAL)) ||
1248 (bp->b_ioflags & BIO_ERROR) || (bp->b_bufsize <= 0)) {
1250 * Either a failed I/O or we were asked to free or not
1253 bp->b_flags |= B_INVAL;
1254 if (LIST_FIRST(&bp->b_dep) != NULL)
1256 if (bp->b_flags & B_DELWRI) {
1257 atomic_subtract_int(&numdirtybuffers, 1);
1258 numdirtywakeup(lodirtybuffers);
1260 bp->b_flags &= ~(B_DELWRI | B_CACHE);
1261 if ((bp->b_flags & B_VMIO) == 0) {
1270 * We must clear B_RELBUF if B_DELWRI is set. If vfs_vmio_release()
1271 * is called with B_DELWRI set, the underlying pages may wind up
1272 * getting freed causing a previous write (bdwrite()) to get 'lost'
1273 * because pages associated with a B_DELWRI bp are marked clean.
1275 * We still allow the B_INVAL case to call vfs_vmio_release(), even
1276 * if B_DELWRI is set.
1278 * If B_DELWRI is not set we may have to set B_RELBUF if we are low
1279 * on pages to return pages to the VM page queues.
1281 if (bp->b_flags & B_DELWRI)
1282 bp->b_flags &= ~B_RELBUF;
1283 else if (vm_page_count_severe()) {
1285 * XXX This lock may not be necessary since BKGRDINPROG
1286 * cannot be set while we hold the buf lock, it can only be
1287 * cleared if it is already pending.
1291 if (!(bp->b_vflags & BV_BKGRDINPROG))
1292 bp->b_flags |= B_RELBUF;
1293 VI_UNLOCK(bp->b_vp);
1295 bp->b_flags |= B_RELBUF;
1299 * VMIO buffer rundown. It is not very necessary to keep a VMIO buffer
1300 * constituted, not even NFS buffers now. Two flags effect this. If
1301 * B_INVAL, the struct buf is invalidated but the VM object is kept
1302 * around ( i.e. so it is trivial to reconstitute the buffer later ).
1304 * If BIO_ERROR or B_NOCACHE is set, pages in the VM object will be
1305 * invalidated. BIO_ERROR cannot be set for a failed write unless the
1306 * buffer is also B_INVAL because it hits the re-dirtying code above.
1308 * Normally we can do this whether a buffer is B_DELWRI or not. If
1309 * the buffer is an NFS buffer, it is tracking piecemeal writes or
1310 * the commit state and we cannot afford to lose the buffer. If the
1311 * buffer has a background write in progress, we need to keep it
1312 * around to prevent it from being reconstituted and starting a second
1315 if ((bp->b_flags & B_VMIO)
1316 && !(bp->b_vp->v_mount != NULL &&
1317 (bp->b_vp->v_mount->mnt_vfc->vfc_flags & VFCF_NETWORK) != 0 &&
1318 !vn_isdisk(bp->b_vp, NULL) &&
1319 (bp->b_flags & B_DELWRI))
1331 * Get the base offset and length of the buffer. Note that
1332 * in the VMIO case if the buffer block size is not
1333 * page-aligned then b_data pointer may not be page-aligned.
1334 * But our b_pages[] array *IS* page aligned.
1336 * block sizes less then DEV_BSIZE (usually 512) are not
1337 * supported due to the page granularity bits (m->valid,
1338 * m->dirty, etc...).
1340 * See man buf(9) for more information
1342 resid = bp->b_bufsize;
1343 foff = bp->b_offset;
1344 VM_OBJECT_LOCK(obj);
1345 for (i = 0; i < bp->b_npages; i++) {
1351 * If we hit a bogus page, fixup *all* the bogus pages
1354 if (m == bogus_page) {
1355 poff = OFF_TO_IDX(bp->b_offset);
1358 for (j = i; j < bp->b_npages; j++) {
1360 mtmp = bp->b_pages[j];
1361 if (mtmp == bogus_page) {
1362 mtmp = vm_page_lookup(obj, poff + j);
1364 panic("brelse: page missing\n");
1366 bp->b_pages[j] = mtmp;
1370 if ((bp->b_flags & B_INVAL) == 0) {
1372 trunc_page((vm_offset_t)bp->b_data), bp->b_pages, bp->b_npages);
1376 if ((bp->b_flags & B_NOCACHE) ||
1377 (bp->b_ioflags & BIO_ERROR)) {
1378 int poffset = foff & PAGE_MASK;
1379 int presid = resid > (PAGE_SIZE - poffset) ?
1380 (PAGE_SIZE - poffset) : resid;
1382 KASSERT(presid >= 0, ("brelse: extra page"));
1383 vm_page_lock_queues();
1384 vm_page_set_invalid(m, poffset, presid);
1385 vm_page_unlock_queues();
1387 printf("avoided corruption bug in bogus_page/brelse code\n");
1389 resid -= PAGE_SIZE - (foff & PAGE_MASK);
1390 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK;
1392 VM_OBJECT_UNLOCK(obj);
1393 if (bp->b_flags & (B_INVAL | B_RELBUF))
1394 vfs_vmio_release(bp);
1396 } else if (bp->b_flags & B_VMIO) {
1398 if (bp->b_flags & (B_INVAL | B_RELBUF)) {
1399 vfs_vmio_release(bp);
1404 if (bp->b_qindex != QUEUE_NONE)
1405 panic("brelse: free buffer onto another queue???");
1406 if (BUF_REFCNT(bp) > 1) {
1407 /* do not release to free list */
1416 /* buffers with no memory */
1417 if (bp->b_bufsize == 0) {
1418 bp->b_flags |= B_INVAL;
1419 bp->b_xflags &= ~(BX_BKGRDWRITE | BX_ALTDATA);
1420 if (bp->b_vflags & BV_BKGRDINPROG)
1421 panic("losing buffer 1");
1422 if (bp->b_kvasize) {
1423 bp->b_qindex = QUEUE_EMPTYKVA;
1425 bp->b_qindex = QUEUE_EMPTY;
1427 TAILQ_INSERT_HEAD(&bufqueues[bp->b_qindex], bp, b_freelist);
1429 /* buffers with junk contents */
1430 } else if (bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF) ||
1431 (bp->b_ioflags & BIO_ERROR)) {
1432 bp->b_flags |= B_INVAL;
1433 bp->b_xflags &= ~(BX_BKGRDWRITE | BX_ALTDATA);
1434 if (bp->b_vflags & BV_BKGRDINPROG)
1435 panic("losing buffer 2");
1436 bp->b_qindex = QUEUE_CLEAN;
1437 TAILQ_INSERT_HEAD(&bufqueues[QUEUE_CLEAN], bp, b_freelist);
1439 /* remaining buffers */
1441 if (bp->b_flags & B_DELWRI)
1442 bp->b_qindex = QUEUE_DIRTY;
1444 bp->b_qindex = QUEUE_CLEAN;
1445 if (bp->b_flags & B_AGE)
1446 TAILQ_INSERT_HEAD(&bufqueues[bp->b_qindex], bp, b_freelist);
1448 TAILQ_INSERT_TAIL(&bufqueues[bp->b_qindex], bp, b_freelist);
1450 mtx_unlock(&bqlock);
1453 * If B_INVAL and B_DELWRI is set, clear B_DELWRI. We have already
1454 * placed the buffer on the correct queue. We must also disassociate
1455 * the device and vnode for a B_INVAL buffer so gbincore() doesn't
1458 if (bp->b_flags & B_INVAL) {
1459 if (bp->b_flags & B_DELWRI)
1466 * Fixup numfreebuffers count. The bp is on an appropriate queue
1467 * unless locked. We then bump numfreebuffers if it is not B_DELWRI.
1468 * We've already handled the B_INVAL case ( B_DELWRI will be clear
1469 * if B_INVAL is set ).
1472 if (!(bp->b_flags & B_DELWRI))
1476 * Something we can maybe free or reuse
1478 if (bp->b_bufsize || bp->b_kvasize)
1481 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF | B_DIRECT);
1482 if ((bp->b_flags & B_DELWRI) == 0 && (bp->b_xflags & BX_VNDIRTY))
1483 panic("brelse: not dirty");
1490 * Release a buffer back to the appropriate queue but do not try to free
1491 * it. The buffer is expected to be used again soon.
1493 * bqrelse() is used by bdwrite() to requeue a delayed write, and used by
1494 * biodone() to requeue an async I/O on completion. It is also used when
1495 * known good buffers need to be requeued but we think we may need the data
1498 * XXX we should be able to leave the B_RELBUF hint set on completion.
1501 bqrelse(struct buf *bp)
1507 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)),
1508 ("bqrelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp));
1510 if (bp->b_qindex != QUEUE_NONE)
1511 panic("bqrelse: free buffer onto another queue???");
1512 if (BUF_REFCNT(bp) > 1) {
1513 /* do not release to free list */
1519 /* buffers with stale but valid contents */
1520 if (bp->b_flags & B_DELWRI) {
1521 bp->b_qindex = QUEUE_DIRTY;
1522 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_DIRTY], bp, b_freelist);
1525 * XXX This lock may not be necessary since BKGRDINPROG
1526 * cannot be set while we hold the buf lock, it can only be
1527 * cleared if it is already pending.
1530 if (!vm_page_count_severe() || bp->b_vflags & BV_BKGRDINPROG) {
1531 VI_UNLOCK(bp->b_vp);
1532 bp->b_qindex = QUEUE_CLEAN;
1533 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_CLEAN], bp,
1537 * We are too low on memory, we have to try to free
1538 * the buffer (most importantly: the wired pages
1539 * making up its backing store) *now*.
1541 VI_UNLOCK(bp->b_vp);
1542 mtx_unlock(&bqlock);
1548 mtx_unlock(&bqlock);
1550 if ((bp->b_flags & B_INVAL) || !(bp->b_flags & B_DELWRI))
1554 * Something we can maybe free or reuse.
1556 if (bp->b_bufsize && !(bp->b_flags & B_DELWRI))
1559 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF);
1560 if ((bp->b_flags & B_DELWRI) == 0 && (bp->b_xflags & BX_VNDIRTY))
1561 panic("bqrelse: not dirty");
1567 /* Give pages used by the bp back to the VM system (where possible) */
1569 vfs_vmio_release(struct buf *bp)
1575 VM_OBJECT_LOCK(bp->b_object);
1576 vm_page_lock_queues();
1577 for (i = 0; i < bp->b_npages; i++) {
1579 bp->b_pages[i] = NULL;
1581 * In order to keep page LRU ordering consistent, put
1582 * everything on the inactive queue.
1584 vm_page_unwire(m, 0);
1586 * We don't mess with busy pages, it is
1587 * the responsibility of the process that
1588 * busied the pages to deal with them.
1590 if ((m->flags & PG_BUSY) || (m->busy != 0))
1593 if (m->wire_count == 0) {
1595 * Might as well free the page if we can and it has
1596 * no valid data. We also free the page if the
1597 * buffer was used for direct I/O
1599 if ((bp->b_flags & B_ASYNC) == 0 && !m->valid &&
1600 m->hold_count == 0) {
1604 } else if (bp->b_flags & B_DIRECT) {
1605 vm_page_try_to_free(m);
1606 } else if (vm_page_count_severe()) {
1607 vm_page_try_to_cache(m);
1611 vm_page_unlock_queues();
1612 VM_OBJECT_UNLOCK(bp->b_object);
1613 pmap_qremove(trunc_page((vm_offset_t) bp->b_data), bp->b_npages);
1615 if (bp->b_bufsize) {
1620 bp->b_flags &= ~B_VMIO;
1626 * Check to see if a block at a particular lbn is available for a clustered
1630 vfs_bio_clcheck(struct vnode *vp, int size, daddr_t lblkno, daddr_t blkno)
1637 /* If the buf isn't in core skip it */
1638 if ((bpa = gbincore(vp, lblkno)) == NULL)
1641 /* If the buf is busy we don't want to wait for it */
1642 if (BUF_LOCK(bpa, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0)
1645 /* Only cluster with valid clusterable delayed write buffers */
1646 if ((bpa->b_flags & (B_DELWRI | B_CLUSTEROK | B_INVAL)) !=
1647 (B_DELWRI | B_CLUSTEROK))
1650 if (bpa->b_bufsize != size)
1654 * Check to see if it is in the expected place on disk and that the
1655 * block has been mapped.
1657 if ((bpa->b_blkno != bpa->b_lblkno) && (bpa->b_blkno == blkno))
1667 * Implement clustered async writes for clearing out B_DELWRI buffers.
1668 * This is much better then the old way of writing only one buffer at
1669 * a time. Note that we may not be presented with the buffers in the
1670 * correct order, so we search for the cluster in both directions.
1673 vfs_bio_awrite(struct buf *bp)
1677 daddr_t lblkno = bp->b_lblkno;
1678 struct vnode *vp = bp->b_vp;
1687 * right now we support clustered writing only to regular files. If
1688 * we find a clusterable block we could be in the middle of a cluster
1689 * rather then at the beginning.
1691 if ((vp->v_type == VREG) &&
1692 (vp->v_mount != 0) && /* Only on nodes that have the size info */
1693 (bp->b_flags & (B_CLUSTEROK | B_INVAL)) == B_CLUSTEROK) {
1695 size = vp->v_mount->mnt_stat.f_iosize;
1696 maxcl = MAXPHYS / size;
1699 for (i = 1; i < maxcl; i++)
1700 if (vfs_bio_clcheck(vp, size, lblkno + i,
1701 bp->b_blkno + ((i * size) >> DEV_BSHIFT)) == 0)
1704 for (j = 1; i + j <= maxcl && j <= lblkno; j++)
1705 if (vfs_bio_clcheck(vp, size, lblkno - j,
1706 bp->b_blkno - ((j * size) >> DEV_BSHIFT)) == 0)
1713 * this is a possible cluster write
1717 nwritten = cluster_wbuild(vp, size, lblkno - j, ncl);
1724 bp->b_flags |= B_ASYNC;
1728 * default (old) behavior, writing out only one block
1730 * XXX returns b_bufsize instead of b_bcount for nwritten?
1732 nwritten = bp->b_bufsize;
1741 * Find and initialize a new buffer header, freeing up existing buffers
1742 * in the bufqueues as necessary. The new buffer is returned locked.
1744 * Important: B_INVAL is not set. If the caller wishes to throw the
1745 * buffer away, the caller must set B_INVAL prior to calling brelse().
1748 * We have insufficient buffer headers
1749 * We have insufficient buffer space
1750 * buffer_map is too fragmented ( space reservation fails )
1751 * If we have to flush dirty buffers ( but we try to avoid this )
1753 * To avoid VFS layer recursion we do not flush dirty buffers ourselves.
1754 * Instead we ask the buf daemon to do it for us. We attempt to
1755 * avoid piecemeal wakeups of the pageout daemon.
1759 getnewbuf(int slpflag, int slptimeo, int size, int maxsize)
1765 static int flushingbufs;
1770 * We can't afford to block since we might be holding a vnode lock,
1771 * which may prevent system daemons from running. We deal with
1772 * low-memory situations by proactively returning memory and running
1773 * async I/O rather then sync I/O.
1776 atomic_add_int(&getnewbufcalls, 1);
1777 atomic_subtract_int(&getnewbufrestarts, 1);
1779 atomic_add_int(&getnewbufrestarts, 1);
1782 * Setup for scan. If we do not have enough free buffers,
1783 * we setup a degenerate case that immediately fails. Note
1784 * that if we are specially marked process, we are allowed to
1785 * dip into our reserves.
1787 * The scanning sequence is nominally: EMPTY->EMPTYKVA->CLEAN
1789 * We start with EMPTYKVA. If the list is empty we backup to EMPTY.
1790 * However, there are a number of cases (defragging, reusing, ...)
1791 * where we cannot backup.
1794 nqindex = QUEUE_EMPTYKVA;
1795 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTYKVA]);
1799 * If no EMPTYKVA buffers and we are either
1800 * defragging or reusing, locate a CLEAN buffer
1801 * to free or reuse. If bufspace useage is low
1802 * skip this step so we can allocate a new buffer.
1804 if (defrag || bufspace >= lobufspace) {
1805 nqindex = QUEUE_CLEAN;
1806 nbp = TAILQ_FIRST(&bufqueues[QUEUE_CLEAN]);
1810 * If we could not find or were not allowed to reuse a
1811 * CLEAN buffer, check to see if it is ok to use an EMPTY
1812 * buffer. We can only use an EMPTY buffer if allocating
1813 * its KVA would not otherwise run us out of buffer space.
1815 if (nbp == NULL && defrag == 0 &&
1816 bufspace + maxsize < hibufspace) {
1817 nqindex = QUEUE_EMPTY;
1818 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTY]);
1823 * Run scan, possibly freeing data and/or kva mappings on the fly
1827 while ((bp = nbp) != NULL) {
1828 int qindex = nqindex;
1831 * Calculate next bp ( we can only use it if we do not block
1832 * or do other fancy things ).
1834 if ((nbp = TAILQ_NEXT(bp, b_freelist)) == NULL) {
1837 nqindex = QUEUE_EMPTYKVA;
1838 if ((nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTYKVA])))
1841 case QUEUE_EMPTYKVA:
1842 nqindex = QUEUE_CLEAN;
1843 if ((nbp = TAILQ_FIRST(&bufqueues[QUEUE_CLEAN])))
1855 if (bp->b_vflags & BV_BKGRDINPROG) {
1856 VI_UNLOCK(bp->b_vp);
1859 VI_UNLOCK(bp->b_vp);
1865 KASSERT(bp->b_qindex == qindex, ("getnewbuf: inconsistant queue %d bp %p", qindex, bp));
1868 * Note: we no longer distinguish between VMIO and non-VMIO
1872 KASSERT((bp->b_flags & B_DELWRI) == 0, ("delwri buffer %p found in queue %d", bp, qindex));
1875 * If we are defragging then we need a buffer with
1876 * b_kvasize != 0. XXX this situation should no longer
1877 * occur, if defrag is non-zero the buffer's b_kvasize
1878 * should also be non-zero at this point. XXX
1880 if (defrag && bp->b_kvasize == 0) {
1881 printf("Warning: defrag empty buffer %p\n", bp);
1886 * Start freeing the bp. This is somewhat involved. nbp
1887 * remains valid only for QUEUE_EMPTY[KVA] bp's.
1890 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0)
1891 panic("getnewbuf: locked buf");
1893 mtx_unlock(&bqlock);
1895 if (qindex == QUEUE_CLEAN) {
1896 if (bp->b_flags & B_VMIO) {
1897 bp->b_flags &= ~B_ASYNC;
1898 vfs_vmio_release(bp);
1905 * NOTE: nbp is now entirely invalid. We can only restart
1906 * the scan from this point on.
1908 * Get the rest of the buffer freed up. b_kva* is still
1909 * valid after this operation.
1912 if (bp->b_rcred != NOCRED) {
1913 crfree(bp->b_rcred);
1914 bp->b_rcred = NOCRED;
1916 if (bp->b_wcred != NOCRED) {
1917 crfree(bp->b_wcred);
1918 bp->b_wcred = NOCRED;
1920 if (LIST_FIRST(&bp->b_dep) != NULL)
1922 if (bp->b_vflags & BV_BKGRDINPROG)
1923 panic("losing buffer 3");
1934 bp->b_blkno = bp->b_lblkno = 0;
1935 bp->b_offset = NOOFFSET;
1941 bp->b_dirtyoff = bp->b_dirtyend = 0;
1942 bp->b_magic = B_MAGIC_BIO;
1943 bp->b_op = &buf_ops_bio;
1944 bp->b_object = NULL;
1946 LIST_INIT(&bp->b_dep);
1949 * If we are defragging then free the buffer.
1952 bp->b_flags |= B_INVAL;
1960 * If we are overcomitted then recover the buffer and its
1961 * KVM space. This occurs in rare situations when multiple
1962 * processes are blocked in getnewbuf() or allocbuf().
1964 if (bufspace >= hibufspace)
1966 if (flushingbufs && bp->b_kvasize != 0) {
1967 bp->b_flags |= B_INVAL;
1972 if (bufspace < lobufspace)
1978 * If we exhausted our list, sleep as appropriate. We may have to
1979 * wakeup various daemons and write out some dirty buffers.
1981 * Generally we are sleeping due to insufficient buffer space.
1988 mtx_unlock(&bqlock);
1990 flags = VFS_BIO_NEED_BUFSPACE;
1992 } else if (bufspace >= hibufspace) {
1994 flags = VFS_BIO_NEED_BUFSPACE;
1997 flags = VFS_BIO_NEED_ANY;
2000 bd_speedup(); /* heeeelp */
2003 needsbuffer |= flags;
2004 while (needsbuffer & flags) {
2005 if (msleep(&needsbuffer, &nblock,
2006 (PRIBIO + 4) | slpflag, waitmsg, slptimeo)) {
2007 mtx_unlock(&nblock);
2011 mtx_unlock(&nblock);
2014 * We finally have a valid bp. We aren't quite out of the
2015 * woods, we still have to reserve kva space. In order
2016 * to keep fragmentation sane we only allocate kva in
2019 maxsize = (maxsize + BKVAMASK) & ~BKVAMASK;
2021 if (maxsize != bp->b_kvasize) {
2022 vm_offset_t addr = 0;
2026 if (vm_map_findspace(buffer_map,
2027 vm_map_min(buffer_map), maxsize, &addr)) {
2029 * Uh oh. Buffer map is to fragmented. We
2030 * must defragment the map.
2032 atomic_add_int(&bufdefragcnt, 1);
2034 bp->b_flags |= B_INVAL;
2039 vm_map_insert(buffer_map, NULL, 0,
2040 addr, addr + maxsize,
2041 VM_PROT_ALL, VM_PROT_ALL, MAP_NOFAULT);
2043 bp->b_kvabase = (caddr_t) addr;
2044 bp->b_kvasize = maxsize;
2045 atomic_add_int(&bufspace, bp->b_kvasize);
2046 atomic_add_int(&bufreusecnt, 1);
2049 bp->b_saveaddr = bp->b_kvabase;
2050 bp->b_data = bp->b_saveaddr;
2058 * buffer flushing daemon. Buffers are normally flushed by the
2059 * update daemon but if it cannot keep up this process starts to
2060 * take the load in an attempt to prevent getnewbuf() from blocking.
2063 static struct kproc_desc buf_kp = {
2068 SYSINIT(bufdaemon, SI_SUB_KTHREAD_BUF, SI_ORDER_FIRST, kproc_start, &buf_kp)
2078 * This process needs to be suspended prior to shutdown sync.
2080 EVENTHANDLER_REGISTER(shutdown_pre_sync, kproc_shutdown, bufdaemonproc,
2084 * This process is allowed to take the buffer cache to the limit
2091 mtx_unlock(&bdlock);
2093 kthread_suspend_check(bufdaemonproc);
2096 * Do the flush. Limit the amount of in-transit I/O we
2097 * allow to build up, otherwise we would completely saturate
2098 * the I/O system. Wakeup any waiting processes before we
2099 * normally would so they can run in parallel with our drain.
2101 while (numdirtybuffers > lodirtybuffers) {
2102 if (flushbufqueues(0) == 0) {
2104 * Could not find any buffers without rollback
2105 * dependencies, so just write the first one
2106 * in the hopes of eventually making progress.
2111 waitrunningbufspace();
2112 numdirtywakeup((lodirtybuffers + hidirtybuffers) / 2);
2116 * Only clear bd_request if we have reached our low water
2117 * mark. The buf_daemon normally waits 1 second and
2118 * then incrementally flushes any dirty buffers that have
2119 * built up, within reason.
2121 * If we were unable to hit our low water mark and couldn't
2122 * find any flushable buffers, we sleep half a second.
2123 * Otherwise we loop immediately.
2126 if (numdirtybuffers <= lodirtybuffers) {
2128 * We reached our low water mark, reset the
2129 * request and sleep until we are needed again.
2130 * The sleep is just so the suspend code works.
2133 msleep(&bd_request, &bdlock, PVM, "psleep", hz);
2136 * We couldn't find any flushable dirty buffers but
2137 * still have too many dirty buffers, we
2138 * have to sleep and try again. (rare)
2140 msleep(&bd_request, &bdlock, PVM, "qsleep", hz / 10);
2148 * Try to flush a buffer in the dirty queue. We must be careful to
2149 * free up B_INVAL buffers instead of write them, which NFS is
2150 * particularly sensitive to.
2152 int flushwithdeps = 0;
2153 SYSCTL_INT(_vfs, OID_AUTO, flushwithdeps, CTLFLAG_RW, &flushwithdeps,
2154 0, "Number of buffers flushed with dependecies that require rollbacks");
2157 flushbufqueues(int flushdeps)
2159 struct thread *td = curthread;
2166 TAILQ_FOREACH(bp, &bufqueues[QUEUE_DIRTY], b_freelist) {
2167 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0)
2169 KASSERT((bp->b_flags & B_DELWRI),
2170 ("unexpected clean buffer %p", bp));
2172 if ((bp->b_vflags & BV_BKGRDINPROG) != 0) {
2173 VI_UNLOCK(bp->b_vp);
2177 VI_UNLOCK(bp->b_vp);
2178 if (bp->b_flags & B_INVAL) {
2180 mtx_unlock(&bqlock);
2185 if (LIST_FIRST(&bp->b_dep) != NULL && buf_countdeps(bp, 0)) {
2186 if (flushdeps == 0) {
2194 * We must hold the lock on a vnode before writing
2195 * one of its buffers. Otherwise we may confuse, or
2196 * in the case of a snapshot vnode, deadlock the
2199 * The lock order here is the reverse of the normal
2200 * of vnode followed by buf lock. This is ok because
2201 * the NOWAIT will prevent deadlock.
2204 if (vn_start_write(vp, &mp, V_NOWAIT) != 0) {
2208 if (vn_lock(vp, LK_EXCLUSIVE | LK_NOWAIT, td) == 0) {
2209 mtx_unlock(&bqlock);
2211 vn_finished_write(mp);
2212 VOP_UNLOCK(vp, 0, td);
2213 flushwithdeps += hasdeps;
2216 vn_finished_write(mp);
2219 mtx_unlock(&bqlock);
2224 * Check to see if a block is currently memory resident.
2227 incore(struct vnode * vp, daddr_t blkno)
2233 bp = gbincore(vp, blkno);
2240 * Returns true if no I/O is needed to access the
2241 * associated VM object. This is like incore except
2242 * it also hunts around in the VM system for the data.
2246 inmem(struct vnode * vp, daddr_t blkno)
2249 vm_offset_t toff, tinc, size;
2254 ASSERT_VOP_LOCKED(vp, "inmem");
2256 if (incore(vp, blkno))
2258 if (vp->v_mount == NULL)
2260 if (VOP_GETVOBJECT(vp, &obj) != 0 || (vp->v_vflag & VV_OBJBUF) == 0)
2264 if (size > vp->v_mount->mnt_stat.f_iosize)
2265 size = vp->v_mount->mnt_stat.f_iosize;
2266 off = (vm_ooffset_t)blkno * (vm_ooffset_t)vp->v_mount->mnt_stat.f_iosize;
2268 VM_OBJECT_LOCK(obj);
2269 for (toff = 0; toff < vp->v_mount->mnt_stat.f_iosize; toff += tinc) {
2270 m = vm_page_lookup(obj, OFF_TO_IDX(off + toff));
2274 if (tinc > PAGE_SIZE - ((toff + off) & PAGE_MASK))
2275 tinc = PAGE_SIZE - ((toff + off) & PAGE_MASK);
2276 if (vm_page_is_valid(m,
2277 (vm_offset_t) ((toff + off) & PAGE_MASK), tinc) == 0)
2280 VM_OBJECT_UNLOCK(obj);
2284 VM_OBJECT_UNLOCK(obj);
2291 * Sets the dirty range for a buffer based on the status of the dirty
2292 * bits in the pages comprising the buffer.
2294 * The range is limited to the size of the buffer.
2296 * This routine is primarily used by NFS, but is generalized for the
2300 vfs_setdirty(struct buf *bp)
2307 * Degenerate case - empty buffer
2310 if (bp->b_bufsize == 0)
2314 * We qualify the scan for modified pages on whether the
2315 * object has been flushed yet. The OBJ_WRITEABLE flag
2316 * is not cleared simply by protecting pages off.
2319 if ((bp->b_flags & B_VMIO) == 0)
2322 object = bp->b_pages[0]->object;
2323 VM_OBJECT_LOCK(object);
2324 if ((object->flags & OBJ_WRITEABLE) && !(object->flags & OBJ_MIGHTBEDIRTY))
2325 printf("Warning: object %p writeable but not mightbedirty\n", object);
2326 if (!(object->flags & OBJ_WRITEABLE) && (object->flags & OBJ_MIGHTBEDIRTY))
2327 printf("Warning: object %p mightbedirty but not writeable\n", object);
2329 if (object->flags & (OBJ_MIGHTBEDIRTY|OBJ_CLEANING)) {
2330 vm_offset_t boffset;
2331 vm_offset_t eoffset;
2333 vm_page_lock_queues();
2335 * test the pages to see if they have been modified directly
2336 * by users through the VM system.
2338 for (i = 0; i < bp->b_npages; i++)
2339 vm_page_test_dirty(bp->b_pages[i]);
2342 * Calculate the encompassing dirty range, boffset and eoffset,
2343 * (eoffset - boffset) bytes.
2346 for (i = 0; i < bp->b_npages; i++) {
2347 if (bp->b_pages[i]->dirty)
2350 boffset = (i << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK);
2352 for (i = bp->b_npages - 1; i >= 0; --i) {
2353 if (bp->b_pages[i]->dirty) {
2357 eoffset = ((i + 1) << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK);
2359 vm_page_unlock_queues();
2361 * Fit it to the buffer.
2364 if (eoffset > bp->b_bcount)
2365 eoffset = bp->b_bcount;
2368 * If we have a good dirty range, merge with the existing
2372 if (boffset < eoffset) {
2373 if (bp->b_dirtyoff > boffset)
2374 bp->b_dirtyoff = boffset;
2375 if (bp->b_dirtyend < eoffset)
2376 bp->b_dirtyend = eoffset;
2379 VM_OBJECT_UNLOCK(object);
2385 * Get a block given a specified block and offset into a file/device.
2386 * The buffers B_DONE bit will be cleared on return, making it almost
2387 * ready for an I/O initiation. B_INVAL may or may not be set on
2388 * return. The caller should clear B_INVAL prior to initiating a
2391 * For a non-VMIO buffer, B_CACHE is set to the opposite of B_INVAL for
2392 * an existing buffer.
2394 * For a VMIO buffer, B_CACHE is modified according to the backing VM.
2395 * If getblk()ing a previously 0-sized invalid buffer, B_CACHE is set
2396 * and then cleared based on the backing VM. If the previous buffer is
2397 * non-0-sized but invalid, B_CACHE will be cleared.
2399 * If getblk() must create a new buffer, the new buffer is returned with
2400 * both B_INVAL and B_CACHE clear unless it is a VMIO buffer, in which
2401 * case it is returned with B_INVAL clear and B_CACHE set based on the
2404 * getblk() also forces a bwrite() for any B_DELWRI buffer whos
2405 * B_CACHE bit is clear.
2407 * What this means, basically, is that the caller should use B_CACHE to
2408 * determine whether the buffer is fully valid or not and should clear
2409 * B_INVAL prior to issuing a read. If the caller intends to validate
2410 * the buffer by loading its data area with something, the caller needs
2411 * to clear B_INVAL. If the caller does this without issuing an I/O,
2412 * the caller should set B_CACHE ( as an optimization ), else the caller
2413 * should issue the I/O and biodone() will set B_CACHE if the I/O was
2414 * a write attempt or if it was a successfull read. If the caller
2415 * intends to issue a READ, the caller must clear B_INVAL and BIO_ERROR
2416 * prior to issuing the READ. biodone() will *not* clear B_INVAL.
2419 getblk(struct vnode * vp, daddr_t blkno, int size, int slpflag, int slptimeo,
2425 ASSERT_VOP_LOCKED(vp, "getblk");
2427 if (size > MAXBSIZE)
2428 panic("getblk: size(%d) > MAXBSIZE(%d)\n", size, MAXBSIZE);
2433 * Block if we are low on buffers. Certain processes are allowed
2434 * to completely exhaust the buffer cache.
2436 * If this check ever becomes a bottleneck it may be better to
2437 * move it into the else, when gbincore() fails. At the moment
2438 * it isn't a problem.
2440 * XXX remove if 0 sections (clean this up after its proven)
2442 if (numfreebuffers == 0) {
2443 if (curthread == PCPU_GET(idlethread))
2446 needsbuffer |= VFS_BIO_NEED_ANY;
2447 mtx_unlock(&nblock);
2451 if ((bp = gbincore(vp, blkno))) {
2454 * Buffer is in-core. If the buffer is not busy, it must
2457 lockflags = LK_EXCLUSIVE | LK_SLEEPFAIL | LK_INTERLOCK;
2459 if (flags & GB_LOCK_NOWAIT)
2460 lockflags |= LK_NOWAIT;
2462 error = BUF_TIMELOCK(bp, lockflags,
2463 VI_MTX(vp), "getblk", slpflag, slptimeo);
2466 * If we slept and got the lock we have to restart in case
2467 * the buffer changed identities.
2469 if (error == ENOLCK)
2471 /* We timed out or were interrupted. */
2476 * The buffer is locked. B_CACHE is cleared if the buffer is
2477 * invalid. Otherwise, for a non-VMIO buffer, B_CACHE is set
2478 * and for a VMIO buffer B_CACHE is adjusted according to the
2481 if (bp->b_flags & B_INVAL)
2482 bp->b_flags &= ~B_CACHE;
2483 else if ((bp->b_flags & (B_VMIO | B_INVAL)) == 0)
2484 bp->b_flags |= B_CACHE;
2488 * check for size inconsistancies for non-VMIO case.
2491 if (bp->b_bcount != size) {
2492 if ((bp->b_flags & B_VMIO) == 0 ||
2493 (size > bp->b_kvasize)) {
2494 if (bp->b_flags & B_DELWRI) {
2495 bp->b_flags |= B_NOCACHE;
2498 if ((bp->b_flags & B_VMIO) &&
2499 (LIST_FIRST(&bp->b_dep) == NULL)) {
2500 bp->b_flags |= B_RELBUF;
2503 bp->b_flags |= B_NOCACHE;
2512 * If the size is inconsistant in the VMIO case, we can resize
2513 * the buffer. This might lead to B_CACHE getting set or
2514 * cleared. If the size has not changed, B_CACHE remains
2515 * unchanged from its previous state.
2518 if (bp->b_bcount != size)
2521 KASSERT(bp->b_offset != NOOFFSET,
2522 ("getblk: no buffer offset"));
2525 * A buffer with B_DELWRI set and B_CACHE clear must
2526 * be committed before we can return the buffer in
2527 * order to prevent the caller from issuing a read
2528 * ( due to B_CACHE not being set ) and overwriting
2531 * Most callers, including NFS and FFS, need this to
2532 * operate properly either because they assume they
2533 * can issue a read if B_CACHE is not set, or because
2534 * ( for example ) an uncached B_DELWRI might loop due
2535 * to softupdates re-dirtying the buffer. In the latter
2536 * case, B_CACHE is set after the first write completes,
2537 * preventing further loops.
2538 * NOTE! b*write() sets B_CACHE. If we cleared B_CACHE
2539 * above while extending the buffer, we cannot allow the
2540 * buffer to remain with B_CACHE set after the write
2541 * completes or it will represent a corrupt state. To
2542 * deal with this we set B_NOCACHE to scrap the buffer
2545 * We might be able to do something fancy, like setting
2546 * B_CACHE in bwrite() except if B_DELWRI is already set,
2547 * so the below call doesn't set B_CACHE, but that gets real
2548 * confusing. This is much easier.
2551 if ((bp->b_flags & (B_CACHE|B_DELWRI)) == B_DELWRI) {
2552 bp->b_flags |= B_NOCACHE;
2558 bp->b_flags &= ~B_DONE;
2560 int bsize, maxsize, vmio;
2564 * Buffer is not in-core, create new buffer. The buffer
2565 * returned by getnewbuf() is locked. Note that the returned
2566 * buffer is also considered valid (not marked B_INVAL).
2570 * If the user does not want us to create the buffer, bail out
2573 if (flags & GB_NOCREAT) {
2577 if (vn_isdisk(vp, NULL))
2579 else if (vp->v_mountedhere)
2580 bsize = vp->v_mountedhere->mnt_stat.f_iosize;
2581 else if (vp->v_mount)
2582 bsize = vp->v_mount->mnt_stat.f_iosize;
2586 if (vp->v_bsize != bsize) {
2588 printf("WARNING: Wrong block size on vnode: %d should be %d\n", vp->v_bsize, bsize);
2590 vp->v_bsize = bsize;
2593 offset = blkno * bsize;
2594 vmio = (VOP_GETVOBJECT(vp, NULL) == 0) &&
2595 (vp->v_vflag & VV_OBJBUF);
2596 maxsize = vmio ? size + (offset & PAGE_MASK) : size;
2597 maxsize = imax(maxsize, bsize);
2599 if ((bp = getnewbuf(slpflag, slptimeo, size, maxsize)) == NULL) {
2600 if (slpflag || slptimeo) {
2608 * This code is used to make sure that a buffer is not
2609 * created while the getnewbuf routine is blocked.
2610 * This can be a problem whether the vnode is locked or not.
2611 * If the buffer is created out from under us, we have to
2612 * throw away the one we just created. There is now window
2613 * race because we are safely running at splbio() from the
2614 * point of the duplicate buffer creation through to here,
2615 * and we've locked the buffer.
2617 * Note: this must occur before we associate the buffer
2618 * with the vp especially considering limitations in
2619 * the splay tree implementation when dealing with duplicate
2623 if (gbincore(vp, blkno)) {
2625 bp->b_flags |= B_INVAL;
2631 * Insert the buffer into the hash, so that it can
2632 * be found by incore.
2634 bp->b_blkno = bp->b_lblkno = blkno;
2635 bp->b_offset = offset;
2641 * set B_VMIO bit. allocbuf() the buffer bigger. Since the
2642 * buffer size starts out as 0, B_CACHE will be set by
2643 * allocbuf() for the VMIO case prior to it testing the
2644 * backing store for validity.
2648 bp->b_flags |= B_VMIO;
2649 #if defined(VFS_BIO_DEBUG)
2650 if (vn_canvmio(vp) != TRUE)
2651 printf("getblk: VMIO on vnode type %d\n",
2654 VOP_GETVOBJECT(vp, &bp->b_object);
2656 bp->b_flags &= ~B_VMIO;
2657 bp->b_object = NULL;
2663 bp->b_flags &= ~B_DONE;
2665 KASSERT(BUF_REFCNT(bp) == 1, ("getblk: bp %p not locked",bp));
2670 * Get an empty, disassociated buffer of given size. The buffer is initially
2680 maxsize = (size + BKVAMASK) & ~BKVAMASK;
2683 while ((bp = getnewbuf(0, 0, size, maxsize)) == 0)
2687 bp->b_flags |= B_INVAL; /* b_dep cleared by getnewbuf() */
2688 KASSERT(BUF_REFCNT(bp) == 1, ("geteblk: bp %p not locked",bp));
2694 * This code constitutes the buffer memory from either anonymous system
2695 * memory (in the case of non-VMIO operations) or from an associated
2696 * VM object (in the case of VMIO operations). This code is able to
2697 * resize a buffer up or down.
2699 * Note that this code is tricky, and has many complications to resolve
2700 * deadlock or inconsistant data situations. Tread lightly!!!
2701 * There are B_CACHE and B_DELWRI interactions that must be dealt with by
2702 * the caller. Calling this code willy nilly can result in the loss of data.
2704 * allocbuf() only adjusts B_CACHE for VMIO buffers. getblk() deals with
2705 * B_CACHE for the non-VMIO case.
2709 allocbuf(struct buf *bp, int size)
2711 int newbsize, mbsize;
2716 if (BUF_REFCNT(bp) == 0)
2717 panic("allocbuf: buffer not busy");
2719 if (bp->b_kvasize < size)
2720 panic("allocbuf: buffer too small");
2722 if ((bp->b_flags & B_VMIO) == 0) {
2726 * Just get anonymous memory from the kernel. Don't
2727 * mess with B_CACHE.
2729 mbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1);
2730 if (bp->b_flags & B_MALLOC)
2733 newbsize = round_page(size);
2735 if (newbsize < bp->b_bufsize) {
2737 * malloced buffers are not shrunk
2739 if (bp->b_flags & B_MALLOC) {
2741 bp->b_bcount = size;
2743 free(bp->b_data, M_BIOBUF);
2744 if (bp->b_bufsize) {
2745 atomic_subtract_int(
2751 bp->b_saveaddr = bp->b_kvabase;
2752 bp->b_data = bp->b_saveaddr;
2754 bp->b_flags &= ~B_MALLOC;
2760 (vm_offset_t) bp->b_data + newbsize,
2761 (vm_offset_t) bp->b_data + bp->b_bufsize);
2762 } else if (newbsize > bp->b_bufsize) {
2764 * We only use malloced memory on the first allocation.
2765 * and revert to page-allocated memory when the buffer
2769 * There is a potential smp race here that could lead
2770 * to bufmallocspace slightly passing the max. It
2771 * is probably extremely rare and not worth worrying
2774 if ( (bufmallocspace < maxbufmallocspace) &&
2775 (bp->b_bufsize == 0) &&
2776 (mbsize <= PAGE_SIZE/2)) {
2778 bp->b_data = malloc(mbsize, M_BIOBUF, M_WAITOK);
2779 bp->b_bufsize = mbsize;
2780 bp->b_bcount = size;
2781 bp->b_flags |= B_MALLOC;
2782 atomic_add_int(&bufmallocspace, mbsize);
2788 * If the buffer is growing on its other-than-first allocation,
2789 * then we revert to the page-allocation scheme.
2791 if (bp->b_flags & B_MALLOC) {
2792 origbuf = bp->b_data;
2793 origbufsize = bp->b_bufsize;
2794 bp->b_data = bp->b_kvabase;
2795 if (bp->b_bufsize) {
2796 atomic_subtract_int(&bufmallocspace,
2801 bp->b_flags &= ~B_MALLOC;
2802 newbsize = round_page(newbsize);
2806 (vm_offset_t) bp->b_data + bp->b_bufsize,
2807 (vm_offset_t) bp->b_data + newbsize);
2809 bcopy(origbuf, bp->b_data, origbufsize);
2810 free(origbuf, M_BIOBUF);
2816 newbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1);
2817 desiredpages = (size == 0) ? 0 :
2818 num_pages((bp->b_offset & PAGE_MASK) + newbsize);
2820 if (bp->b_flags & B_MALLOC)
2821 panic("allocbuf: VMIO buffer can't be malloced");
2823 * Set B_CACHE initially if buffer is 0 length or will become
2826 if (size == 0 || bp->b_bufsize == 0)
2827 bp->b_flags |= B_CACHE;
2829 if (newbsize < bp->b_bufsize) {
2831 * DEV_BSIZE aligned new buffer size is less then the
2832 * DEV_BSIZE aligned existing buffer size. Figure out
2833 * if we have to remove any pages.
2835 if (desiredpages < bp->b_npages) {
2838 vm_page_lock_queues();
2839 for (i = desiredpages; i < bp->b_npages; i++) {
2841 * the page is not freed here -- it
2842 * is the responsibility of
2843 * vnode_pager_setsize
2846 KASSERT(m != bogus_page,
2847 ("allocbuf: bogus page found"));
2848 while (vm_page_sleep_if_busy(m, TRUE, "biodep"))
2849 vm_page_lock_queues();
2851 bp->b_pages[i] = NULL;
2852 vm_page_unwire(m, 0);
2854 vm_page_unlock_queues();
2855 pmap_qremove((vm_offset_t) trunc_page((vm_offset_t)bp->b_data) +
2856 (desiredpages << PAGE_SHIFT), (bp->b_npages - desiredpages));
2857 bp->b_npages = desiredpages;
2859 } else if (size > bp->b_bcount) {
2861 * We are growing the buffer, possibly in a
2862 * byte-granular fashion.
2870 * Step 1, bring in the VM pages from the object,
2871 * allocating them if necessary. We must clear
2872 * B_CACHE if these pages are not valid for the
2873 * range covered by the buffer.
2879 VM_OBJECT_LOCK(obj);
2880 while (bp->b_npages < desiredpages) {
2884 pi = OFF_TO_IDX(bp->b_offset) + bp->b_npages;
2885 if ((m = vm_page_lookup(obj, pi)) == NULL) {
2887 * note: must allocate system pages
2888 * since blocking here could intefere
2889 * with paging I/O, no matter which
2892 m = vm_page_alloc(obj, pi,
2893 VM_ALLOC_SYSTEM | VM_ALLOC_WIRED);
2895 atomic_add_int(&vm_pageout_deficit,
2896 desiredpages - bp->b_npages);
2897 VM_OBJECT_UNLOCK(obj);
2899 VM_OBJECT_LOCK(obj);
2901 vm_page_lock_queues();
2903 vm_page_unlock_queues();
2904 bp->b_flags &= ~B_CACHE;
2905 bp->b_pages[bp->b_npages] = m;
2912 * We found a page. If we have to sleep on it,
2913 * retry because it might have gotten freed out
2916 * We can only test PG_BUSY here. Blocking on
2917 * m->busy might lead to a deadlock:
2919 * vm_fault->getpages->cluster_read->allocbuf
2922 vm_page_lock_queues();
2923 if (vm_page_sleep_if_busy(m, FALSE, "pgtblk"))
2927 * We have a good page. Should we wakeup the
2930 if ((curproc != pageproc) &&
2931 ((m->queue - m->pc) == PQ_CACHE) &&
2932 ((cnt.v_free_count + cnt.v_cache_count) <
2933 (cnt.v_free_min + cnt.v_cache_min))) {
2934 pagedaemon_wakeup();
2937 vm_page_unlock_queues();
2938 bp->b_pages[bp->b_npages] = m;
2943 * Step 2. We've loaded the pages into the buffer,
2944 * we have to figure out if we can still have B_CACHE
2945 * set. Note that B_CACHE is set according to the
2946 * byte-granular range ( bcount and size ), new the
2947 * aligned range ( newbsize ).
2949 * The VM test is against m->valid, which is DEV_BSIZE
2950 * aligned. Needless to say, the validity of the data
2951 * needs to also be DEV_BSIZE aligned. Note that this
2952 * fails with NFS if the server or some other client
2953 * extends the file's EOF. If our buffer is resized,
2954 * B_CACHE may remain set! XXX
2957 toff = bp->b_bcount;
2958 tinc = PAGE_SIZE - ((bp->b_offset + toff) & PAGE_MASK);
2960 while ((bp->b_flags & B_CACHE) && toff < size) {
2963 if (tinc > (size - toff))
2966 pi = ((bp->b_offset & PAGE_MASK) + toff) >>
2979 VM_OBJECT_UNLOCK(obj);
2982 * Step 3, fixup the KVM pmap. Remember that
2983 * bp->b_data is relative to bp->b_offset, but
2984 * bp->b_offset may be offset into the first page.
2987 bp->b_data = (caddr_t)
2988 trunc_page((vm_offset_t)bp->b_data);
2990 (vm_offset_t)bp->b_data,
2995 bp->b_data = (caddr_t)((vm_offset_t)bp->b_data |
2996 (vm_offset_t)(bp->b_offset & PAGE_MASK));
2999 if (newbsize < bp->b_bufsize)
3001 bp->b_bufsize = newbsize; /* actual buffer allocation */
3002 bp->b_bcount = size; /* requested buffer size */
3007 biodone(struct bio *bp)
3010 mtx_lock(&bdonelock);
3011 bp->bio_flags |= BIO_DONE;
3012 if (bp->bio_done == NULL)
3014 mtx_unlock(&bdonelock);
3015 if (bp->bio_done != NULL)
3020 * Wait for a BIO to finish.
3022 * XXX: resort to a timeout for now. The optimal locking (if any) for this
3023 * case is not yet clear.
3026 biowait(struct bio *bp, const char *wchan)
3029 mtx_lock(&bdonelock);
3030 while ((bp->bio_flags & BIO_DONE) == 0)
3031 msleep(bp, &bdonelock, PRIBIO, wchan, hz / 10);
3032 mtx_unlock(&bdonelock);
3033 if (bp->bio_error != 0)
3034 return (bp->bio_error);
3035 if (!(bp->bio_flags & BIO_ERROR))
3041 biofinish(struct bio *bp, struct devstat *stat, int error)
3045 bp->bio_error = error;
3046 bp->bio_flags |= BIO_ERROR;
3049 devstat_end_transaction_bio(stat, bp);
3056 * Wait for buffer I/O completion, returning error status. The buffer
3057 * is left locked and B_DONE on return. B_EINTR is converted into an EINTR
3058 * error and cleared.
3061 bufwait(struct buf *bp)
3066 if (bp->b_iocmd == BIO_READ)
3067 bwait(bp, PRIBIO, "biord");
3069 bwait(bp, PRIBIO, "biowr");
3071 if (bp->b_flags & B_EINTR) {
3072 bp->b_flags &= ~B_EINTR;
3075 if (bp->b_ioflags & BIO_ERROR) {
3076 return (bp->b_error ? bp->b_error : EIO);
3083 * Call back function from struct bio back up to struct buf.
3086 bufdonebio(struct bio *bp)
3089 /* Device drivers may or may not hold giant, hold it here. */
3091 bufdone(bp->bio_caller2);
3096 dev_strategy(struct buf *bp)
3101 if ((!bp->b_iocmd) || (bp->b_iocmd & (bp->b_iocmd - 1)))
3102 panic("b_iocmd botch");
3103 bp->b_io.bio_done = bufdonebio;
3104 bp->b_io.bio_caller2 = bp;
3105 dev = bp->b_io.bio_dev;
3106 KASSERT(dev->si_refcount > 0,
3107 ("dev_strategy on un-referenced struct cdev *(%s)",
3109 csw = dev_refthread(dev);
3111 bp->b_error = ENXIO;
3112 bp->b_ioflags = BIO_ERROR;
3113 mtx_lock(&Giant); /* XXX: too defensive ? */
3115 mtx_unlock(&Giant); /* XXX: too defensive ? */
3118 (*csw->d_strategy)(&bp->b_io);
3125 * Finish I/O on a buffer, optionally calling a completion function.
3126 * This is usually called from an interrupt so process blocking is
3129 * biodone is also responsible for setting B_CACHE in a B_VMIO bp.
3130 * In a non-VMIO bp, B_CACHE will be set on the next getblk()
3131 * assuming B_INVAL is clear.
3133 * For the VMIO case, we set B_CACHE if the op was a read and no
3134 * read error occured, or if the op was a write. B_CACHE is never
3135 * set if the buffer is invalid or otherwise uncacheable.
3137 * biodone does not mess with B_INVAL, allowing the I/O routine or the
3138 * initiator to leave B_INVAL set to brelse the buffer out of existance
3139 * in the biodone routine.
3142 bufdone(struct buf *bp)
3145 void (*biodone)(struct buf *);
3150 KASSERT(BUF_REFCNT(bp) > 0, ("biodone: bp %p not busy %d", bp, BUF_REFCNT(bp)));
3151 KASSERT(!(bp->b_flags & B_DONE), ("biodone: bp %p already done", bp));
3153 bp->b_flags |= B_DONE;
3154 runningbufwakeup(bp);
3156 if (bp->b_iocmd == BIO_WRITE && bp->b_vp != NULL)
3157 bufobj_wdrop(&bp->b_vp->v_bufobj);
3159 /* call optional completion function if requested */
3160 if (bp->b_iodone != NULL) {
3161 biodone = bp->b_iodone;
3162 bp->b_iodone = NULL;
3167 if (LIST_FIRST(&bp->b_dep) != NULL)
3170 if (bp->b_flags & B_VMIO) {
3176 struct vnode *vp = bp->b_vp;
3180 #if defined(VFS_BIO_DEBUG)
3181 mp_fixme("usecount and vflag accessed without locks.");
3182 if (vp->v_usecount == 0) {
3183 panic("biodone: zero vnode ref count");
3186 if ((vp->v_vflag & VV_OBJBUF) == 0) {
3187 panic("biodone: vnode is not setup for merged cache");
3191 foff = bp->b_offset;
3192 KASSERT(bp->b_offset != NOOFFSET,
3193 ("biodone: no buffer offset"));
3195 VM_OBJECT_LOCK(obj);
3196 #if defined(VFS_BIO_DEBUG)
3197 if (obj->paging_in_progress < bp->b_npages) {
3198 printf("biodone: paging in progress(%d) < bp->b_npages(%d)\n",
3199 obj->paging_in_progress, bp->b_npages);
3204 * Set B_CACHE if the op was a normal read and no error
3205 * occured. B_CACHE is set for writes in the b*write()
3208 iosize = bp->b_bcount - bp->b_resid;
3209 if (bp->b_iocmd == BIO_READ &&
3210 !(bp->b_flags & (B_INVAL|B_NOCACHE)) &&
3211 !(bp->b_ioflags & BIO_ERROR)) {
3212 bp->b_flags |= B_CACHE;
3214 vm_page_lock_queues();
3215 for (i = 0; i < bp->b_npages; i++) {
3219 resid = ((foff + PAGE_SIZE) & ~(off_t)PAGE_MASK) - foff;
3224 * cleanup bogus pages, restoring the originals
3227 if (m == bogus_page) {
3229 m = vm_page_lookup(obj, OFF_TO_IDX(foff));
3231 panic("biodone: page disappeared!");
3233 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), bp->b_pages, bp->b_npages);
3235 #if defined(VFS_BIO_DEBUG)
3236 if (OFF_TO_IDX(foff) != m->pindex) {
3238 "biodone: foff(%jd)/m->pindex(%ju) mismatch\n",
3239 (intmax_t)foff, (uintmax_t)m->pindex);
3244 * In the write case, the valid and clean bits are
3245 * already changed correctly ( see bdwrite() ), so we
3246 * only need to do this here in the read case.
3248 if ((bp->b_iocmd == BIO_READ) && !bogusflag && resid > 0) {
3249 vfs_page_set_valid(bp, foff, i, m);
3253 * when debugging new filesystems or buffer I/O methods, this
3254 * is the most common error that pops up. if you see this, you
3255 * have not set the page busy flag correctly!!!
3258 printf("biodone: page busy < 0, "
3259 "pindex: %d, foff: 0x(%x,%x), "
3260 "resid: %d, index: %d\n",
3261 (int) m->pindex, (int)(foff >> 32),
3262 (int) foff & 0xffffffff, resid, i);
3263 if (!vn_isdisk(vp, NULL))
3264 printf(" iosize: %jd, lblkno: %jd, flags: 0x%x, npages: %d\n",
3265 (intmax_t)bp->b_vp->v_mount->mnt_stat.f_iosize,
3266 (intmax_t) bp->b_lblkno,
3267 bp->b_flags, bp->b_npages);
3269 printf(" VDEV, lblkno: %jd, flags: 0x%x, npages: %d\n",
3270 (intmax_t) bp->b_lblkno,
3271 bp->b_flags, bp->b_npages);
3272 printf(" valid: 0x%lx, dirty: 0x%lx, wired: %d\n",
3273 (u_long)m->valid, (u_long)m->dirty,
3275 panic("biodone: page busy < 0\n");
3277 vm_page_io_finish(m);
3278 vm_object_pip_subtract(obj, 1);
3279 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK;
3282 vm_page_unlock_queues();
3283 vm_object_pip_wakeupn(obj, 0);
3284 VM_OBJECT_UNLOCK(obj);
3288 * For asynchronous completions, release the buffer now. The brelse
3289 * will do a wakeup there if necessary - so no need to do a wakeup
3290 * here in the async case. The sync case always needs to do a wakeup.
3293 if (bp->b_flags & B_ASYNC) {
3294 if ((bp->b_flags & (B_NOCACHE | B_INVAL | B_RELBUF)) || (bp->b_ioflags & BIO_ERROR))
3305 * This routine is called in lieu of iodone in the case of
3306 * incomplete I/O. This keeps the busy status for pages
3310 vfs_unbusy_pages(struct buf *bp)
3316 runningbufwakeup(bp);
3317 if (!(bp->b_flags & B_VMIO))
3321 VM_OBJECT_LOCK(obj);
3322 vm_page_lock_queues();
3323 for (i = 0; i < bp->b_npages; i++) {
3325 if (m == bogus_page) {
3326 m = vm_page_lookup(obj, OFF_TO_IDX(bp->b_offset) + i);
3328 panic("vfs_unbusy_pages: page missing\n");
3331 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), bp->b_pages, bp->b_npages);
3333 vm_object_pip_subtract(obj, 1);
3334 vm_page_io_finish(m);
3336 vm_page_unlock_queues();
3337 vm_object_pip_wakeupn(obj, 0);
3338 VM_OBJECT_UNLOCK(obj);
3342 * vfs_page_set_valid:
3344 * Set the valid bits in a page based on the supplied offset. The
3345 * range is restricted to the buffer's size.
3347 * This routine is typically called after a read completes.
3350 vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, int pageno, vm_page_t m)
3352 vm_ooffset_t soff, eoff;
3354 mtx_assert(&vm_page_queue_mtx, MA_OWNED);
3356 * Start and end offsets in buffer. eoff - soff may not cross a
3357 * page boundry or cross the end of the buffer. The end of the
3358 * buffer, in this case, is our file EOF, not the allocation size
3362 eoff = (off + PAGE_SIZE) & ~(off_t)PAGE_MASK;
3363 if (eoff > bp->b_offset + bp->b_bcount)
3364 eoff = bp->b_offset + bp->b_bcount;
3367 * Set valid range. This is typically the entire buffer and thus the
3371 vm_page_set_validclean(
3373 (vm_offset_t) (soff & PAGE_MASK),
3374 (vm_offset_t) (eoff - soff)
3380 * This routine is called before a device strategy routine.
3381 * It is used to tell the VM system that paging I/O is in
3382 * progress, and treat the pages associated with the buffer
3383 * almost as being PG_BUSY. Also the object paging_in_progress
3384 * flag is handled to make sure that the object doesn't become
3387 * Since I/O has not been initiated yet, certain buffer flags
3388 * such as BIO_ERROR or B_INVAL may be in an inconsistant state
3389 * and should be ignored.
3392 vfs_busy_pages(struct buf *bp, int clear_modify)
3399 if (!(bp->b_flags & B_VMIO))
3403 foff = bp->b_offset;
3404 KASSERT(bp->b_offset != NOOFFSET,
3405 ("vfs_busy_pages: no buffer offset"));
3407 VM_OBJECT_LOCK(obj);
3409 vm_page_lock_queues();
3410 for (i = 0; i < bp->b_npages; i++) {
3413 if (vm_page_sleep_if_busy(m, FALSE, "vbpage"))
3417 for (i = 0; i < bp->b_npages; i++) {
3420 if ((bp->b_flags & B_CLUSTER) == 0) {
3421 vm_object_pip_add(obj, 1);
3422 vm_page_io_start(m);
3425 * When readying a buffer for a read ( i.e
3426 * clear_modify == 0 ), it is important to do
3427 * bogus_page replacement for valid pages in
3428 * partially instantiated buffers. Partially
3429 * instantiated buffers can, in turn, occur when
3430 * reconstituting a buffer from its VM backing store
3431 * base. We only have to do this if B_CACHE is
3432 * clear ( which causes the I/O to occur in the
3433 * first place ). The replacement prevents the read
3434 * I/O from overwriting potentially dirty VM-backed
3435 * pages. XXX bogus page replacement is, uh, bogus.
3436 * It may not work properly with small-block devices.
3437 * We need to find a better way.
3441 vfs_page_set_valid(bp, foff, i, m);
3442 else if (m->valid == VM_PAGE_BITS_ALL &&
3443 (bp->b_flags & B_CACHE) == 0) {
3444 bp->b_pages[i] = bogus_page;
3447 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK;
3449 vm_page_unlock_queues();
3450 VM_OBJECT_UNLOCK(obj);
3452 pmap_qenter(trunc_page((vm_offset_t)bp->b_data),
3453 bp->b_pages, bp->b_npages);
3457 * Tell the VM system that the pages associated with this buffer
3458 * are clean. This is used for delayed writes where the data is
3459 * going to go to disk eventually without additional VM intevention.
3461 * Note that while we only really need to clean through to b_bcount, we
3462 * just go ahead and clean through to b_bufsize.
3465 vfs_clean_pages(struct buf *bp)
3468 vm_ooffset_t foff, noff, eoff;
3471 if (!(bp->b_flags & B_VMIO))
3474 foff = bp->b_offset;
3475 KASSERT(bp->b_offset != NOOFFSET,
3476 ("vfs_clean_pages: no buffer offset"));
3477 VM_OBJECT_LOCK(bp->b_object);
3478 vm_page_lock_queues();
3479 for (i = 0; i < bp->b_npages; i++) {
3481 noff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK;
3484 if (eoff > bp->b_offset + bp->b_bufsize)
3485 eoff = bp->b_offset + bp->b_bufsize;
3486 vfs_page_set_valid(bp, foff, i, m);
3487 /* vm_page_clear_dirty(m, foff & PAGE_MASK, eoff - foff); */
3490 vm_page_unlock_queues();
3491 VM_OBJECT_UNLOCK(bp->b_object);
3495 * vfs_bio_set_validclean:
3497 * Set the range within the buffer to valid and clean. The range is
3498 * relative to the beginning of the buffer, b_offset. Note that b_offset
3499 * itself may be offset from the beginning of the first page.
3504 vfs_bio_set_validclean(struct buf *bp, int base, int size)
3509 if (!(bp->b_flags & B_VMIO))
3513 * Fixup base to be relative to beginning of first page.
3514 * Set initial n to be the maximum number of bytes in the
3515 * first page that can be validated.
3518 base += (bp->b_offset & PAGE_MASK);
3519 n = PAGE_SIZE - (base & PAGE_MASK);
3521 VM_OBJECT_LOCK(bp->b_object);
3522 vm_page_lock_queues();
3523 for (i = base / PAGE_SIZE; size > 0 && i < bp->b_npages; ++i) {
3529 vm_page_set_validclean(m, base & PAGE_MASK, n);
3534 vm_page_unlock_queues();
3535 VM_OBJECT_UNLOCK(bp->b_object);
3541 * clear a buffer. This routine essentially fakes an I/O, so we need
3542 * to clear BIO_ERROR and B_INVAL.
3544 * Note that while we only theoretically need to clear through b_bcount,
3545 * we go ahead and clear through b_bufsize.
3549 vfs_bio_clrbuf(struct buf *bp)
3556 if ((bp->b_flags & (B_VMIO | B_MALLOC)) != B_VMIO) {
3560 bp->b_flags &= ~B_INVAL;
3561 bp->b_ioflags &= ~BIO_ERROR;
3562 VM_OBJECT_LOCK(bp->b_object);
3563 if( (bp->b_npages == 1) && (bp->b_bufsize < PAGE_SIZE) &&
3564 (bp->b_offset & PAGE_MASK) == 0) {
3565 if (bp->b_pages[0] == bogus_page)
3567 mask = (1 << (bp->b_bufsize / DEV_BSIZE)) - 1;
3568 VM_OBJECT_LOCK_ASSERT(bp->b_pages[0]->object, MA_OWNED);
3569 if ((bp->b_pages[0]->valid & mask) == mask)
3571 if (((bp->b_pages[0]->flags & PG_ZERO) == 0) &&
3572 ((bp->b_pages[0]->valid & mask) == 0)) {
3573 bzero(bp->b_data, bp->b_bufsize);
3574 bp->b_pages[0]->valid |= mask;
3578 ea = sa = bp->b_data;
3579 for(i = 0; i < bp->b_npages; i++, sa = ea) {
3580 ea = (caddr_t)trunc_page((vm_offset_t)sa + PAGE_SIZE);
3581 ea = (caddr_t)(vm_offset_t)ulmin(
3582 (u_long)(vm_offset_t)ea,
3583 (u_long)(vm_offset_t)bp->b_data + bp->b_bufsize);
3584 if (bp->b_pages[i] == bogus_page)
3586 j = ((vm_offset_t)sa & PAGE_MASK) / DEV_BSIZE;
3587 mask = ((1 << ((ea - sa) / DEV_BSIZE)) - 1) << j;
3588 VM_OBJECT_LOCK_ASSERT(bp->b_pages[i]->object, MA_OWNED);
3589 if ((bp->b_pages[i]->valid & mask) == mask)
3591 if ((bp->b_pages[i]->valid & mask) == 0) {
3592 if ((bp->b_pages[i]->flags & PG_ZERO) == 0)
3595 for (; sa < ea; sa += DEV_BSIZE, j++) {
3596 if (((bp->b_pages[i]->flags & PG_ZERO) == 0) &&
3597 (bp->b_pages[i]->valid & (1<<j)) == 0)
3598 bzero(sa, DEV_BSIZE);
3601 bp->b_pages[i]->valid |= mask;
3604 VM_OBJECT_UNLOCK(bp->b_object);
3609 * vm_hold_load_pages and vm_hold_free_pages get pages into
3610 * a buffers address space. The pages are anonymous and are
3611 * not associated with a file object.
3614 vm_hold_load_pages(struct buf *bp, vm_offset_t from, vm_offset_t to)
3620 to = round_page(to);
3621 from = round_page(from);
3622 index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT;
3624 VM_OBJECT_LOCK(kernel_object);
3625 for (pg = from; pg < to; pg += PAGE_SIZE, index++) {
3628 * note: must allocate system pages since blocking here
3629 * could intefere with paging I/O, no matter which
3632 p = vm_page_alloc(kernel_object,
3633 ((pg - VM_MIN_KERNEL_ADDRESS) >> PAGE_SHIFT),
3634 VM_ALLOC_SYSTEM | VM_ALLOC_WIRED);
3636 atomic_add_int(&vm_pageout_deficit,
3637 (to - pg) >> PAGE_SHIFT);
3638 VM_OBJECT_UNLOCK(kernel_object);
3640 VM_OBJECT_LOCK(kernel_object);
3643 p->valid = VM_PAGE_BITS_ALL;
3644 pmap_qenter(pg, &p, 1);
3645 bp->b_pages[index] = p;
3646 vm_page_lock_queues();
3648 vm_page_unlock_queues();
3650 VM_OBJECT_UNLOCK(kernel_object);
3651 bp->b_npages = index;
3654 /* Return pages associated with this buf to the vm system */
3656 vm_hold_free_pages(struct buf *bp, vm_offset_t from, vm_offset_t to)
3660 int index, newnpages;
3664 from = round_page(from);
3665 to = round_page(to);
3666 newnpages = index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT;
3668 VM_OBJECT_LOCK(kernel_object);
3669 for (pg = from; pg < to; pg += PAGE_SIZE, index++) {
3670 p = bp->b_pages[index];
3671 if (p && (index < bp->b_npages)) {
3674 "vm_hold_free_pages: blkno: %jd, lblkno: %jd\n",
3675 (intmax_t)bp->b_blkno,
3676 (intmax_t)bp->b_lblkno);
3678 bp->b_pages[index] = NULL;
3679 pmap_qremove(pg, 1);
3680 vm_page_lock_queues();
3682 vm_page_unwire(p, 0);
3684 vm_page_unlock_queues();
3687 VM_OBJECT_UNLOCK(kernel_object);
3688 bp->b_npages = newnpages;
3692 * Map an IO request into kernel virtual address space.
3694 * All requests are (re)mapped into kernel VA space.
3695 * Notice that we use b_bufsize for the size of the buffer
3696 * to be mapped. b_bcount might be modified by the driver.
3698 * Note that even if the caller determines that the address space should
3699 * be valid, a race or a smaller-file mapped into a larger space may
3700 * actually cause vmapbuf() to fail, so all callers of vmapbuf() MUST
3701 * check the return value.
3704 vmapbuf(struct buf *bp)
3710 struct pmap *pmap = &curproc->p_vmspace->vm_pmap;
3712 if (bp->b_bufsize < 0)
3714 prot = VM_PROT_READ;
3715 if (bp->b_iocmd == BIO_READ)
3716 prot |= VM_PROT_WRITE; /* Less backwards than it looks */
3717 for (addr = (caddr_t)trunc_page((vm_offset_t)bp->b_data), pidx = 0;
3718 addr < bp->b_data + bp->b_bufsize;
3719 addr += PAGE_SIZE, pidx++) {
3721 * Do the vm_fault if needed; do the copy-on-write thing
3722 * when reading stuff off device into memory.
3724 * NOTE! Must use pmap_extract() because addr may be in
3725 * the userland address space, and kextract is only guarenteed
3726 * to work for the kernland address space (see: sparc64 port).
3729 if (vm_fault_quick(addr >= bp->b_data ? addr : bp->b_data,
3731 vm_page_lock_queues();
3732 for (i = 0; i < pidx; ++i) {
3733 vm_page_unhold(bp->b_pages[i]);
3734 bp->b_pages[i] = NULL;
3736 vm_page_unlock_queues();
3739 m = pmap_extract_and_hold(pmap, (vm_offset_t)addr, prot);
3742 bp->b_pages[pidx] = m;
3744 if (pidx > btoc(MAXPHYS))
3745 panic("vmapbuf: mapped more than MAXPHYS");
3746 pmap_qenter((vm_offset_t)bp->b_saveaddr, bp->b_pages, pidx);
3748 kva = bp->b_saveaddr;
3749 bp->b_npages = pidx;
3750 bp->b_saveaddr = bp->b_data;
3751 bp->b_data = kva + (((vm_offset_t) bp->b_data) & PAGE_MASK);
3756 * Free the io map PTEs associated with this IO operation.
3757 * We also invalidate the TLB entries and restore the original b_addr.
3760 vunmapbuf(struct buf *bp)
3765 npages = bp->b_npages;
3766 pmap_qremove(trunc_page((vm_offset_t)bp->b_data), npages);
3767 vm_page_lock_queues();
3768 for (pidx = 0; pidx < npages; pidx++)
3769 vm_page_unhold(bp->b_pages[pidx]);
3770 vm_page_unlock_queues();
3772 bp->b_data = bp->b_saveaddr;
3776 bdone(struct buf *bp)
3779 mtx_lock(&bdonelock);
3780 bp->b_flags |= B_DONE;
3782 mtx_unlock(&bdonelock);
3786 bwait(struct buf *bp, u_char pri, const char *wchan)
3789 mtx_lock(&bdonelock);
3790 while ((bp->b_flags & B_DONE) == 0)
3791 msleep(bp, &bdonelock, pri, wchan, 0);
3792 mtx_unlock(&bdonelock);
3795 #if 0 /* this is here to unconfuse p4 diff */
3798 bufstrategy(struct bufobj *bo, struct buf *bp)
3804 KASSERT(vp == bo->bo_vnode, ("Inconsistent vnode bufstrategy"));
3805 KASSERT(vp->v_type != VCHR && vp->v_type != VBLK,
3806 ("Wrong vnode in bufstrategy(bp=%p, vp=%p)", bp, vp));
3807 i = VOP_STRATEGY(vp, bp);
3808 KASSERT(i == 0, ("VOP_STRATEGY failed bp=%p vp=%p", bp, bp->b_vp));
3814 bufobj_wref(struct bufobj *bo)
3817 KASSERT(bo != NULL, ("NULL bo in bufobj_wref"));
3824 bufobj_wdrop(struct bufobj *bo)
3827 KASSERT(bo != NULL, ("NULL bo in bufobj_wdrop"));
3829 KASSERT(bo->bo_numoutput > 0, ("bufobj_wdrop non-positive count"));
3830 if ((--bo->bo_numoutput == 0) && (bo->bo_flag & BO_WWAIT)) {
3831 bo->bo_flag &= ~BO_WWAIT;
3832 wakeup(&bo->bo_numoutput);
3838 bufobj_wwait(struct bufobj *bo, int slpflag, int timeo)
3842 KASSERT(bo != NULL, ("NULL bo in bufobj_wwait"));
3843 ASSERT_BO_LOCKED(bo);
3845 while (bo->bo_numoutput) {
3846 bo->bo_flag |= BO_WWAIT;
3847 error = msleep(&bo->bo_numoutput, BO_MTX(bo),
3848 slpflag | (PRIBIO + 1), "bo_wwait", timeo);
3856 #include "opt_ddb.h"
3858 #include <ddb/ddb.h>
3860 /* DDB command to show buffer data */
3861 DB_SHOW_COMMAND(buffer, db_show_buffer)
3864 struct buf *bp = (struct buf *)addr;
3867 db_printf("usage: show buffer <addr>\n");
3871 db_printf("b_flags = 0x%b\n", (u_int)bp->b_flags, PRINT_BUF_FLAGS);
3873 "b_error = %d, b_bufsize = %ld, b_bcount = %ld, b_resid = %ld\n"
3874 "b_dev = (%d,%d), b_data = %p, b_blkno = %jd\n",
3875 bp->b_error, bp->b_bufsize, bp->b_bcount, bp->b_resid,
3876 major(bp->b_dev), minor(bp->b_dev), bp->b_data,
3877 (intmax_t)bp->b_blkno);
3880 db_printf("b_npages = %d, pages(OBJ, IDX, PA): ", bp->b_npages);
3881 for (i = 0; i < bp->b_npages; i++) {
3884 db_printf("(%p, 0x%lx, 0x%lx)", (void *)m->object,
3885 (u_long)m->pindex, (u_long)VM_PAGE_TO_PHYS(m));
3886 if ((i + 1) < bp->b_npages)