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
14 * $FreeBSD: src/sys/kern/vfs_bio.c,v 1.242.2.20 2003/05/28 18:38:10 alc Exp $
15 * $DragonFly: src/sys/kern/vfs_bio.c,v 1.35 2005/04/15 19:08:11 dillon Exp $
19 * this file contains a new buffer I/O scheme implementing a coherent
20 * VM object and buffer cache scheme. Pains have been taken to make
21 * sure that the performance degradation associated with schemes such
22 * as this is not realized.
24 * Author: John S. Dyson
25 * Significant help during the development and debugging phases
26 * had been provided by David Greenman, also of the FreeBSD core team.
28 * see man buf(9) for more info.
31 #include <sys/param.h>
32 #include <sys/systm.h>
35 #include <sys/eventhandler.h>
37 #include <sys/malloc.h>
38 #include <sys/mount.h>
39 #include <sys/kernel.h>
40 #include <sys/kthread.h>
42 #include <sys/reboot.h>
43 #include <sys/resourcevar.h>
44 #include <sys/sysctl.h>
45 #include <sys/vmmeter.h>
46 #include <sys/vnode.h>
49 #include <vm/vm_param.h>
50 #include <vm/vm_kern.h>
51 #include <vm/vm_pageout.h>
52 #include <vm/vm_page.h>
53 #include <vm/vm_object.h>
54 #include <vm/vm_extern.h>
55 #include <vm/vm_map.h>
58 #include <sys/thread2.h>
59 #include <vm/vm_page2.h>
61 static MALLOC_DEFINE(M_BIOBUF, "BIO buffer", "BIO buffer");
63 struct bio_ops bioops; /* I/O operation notification */
65 struct buf *buf; /* buffer header pool */
66 struct swqueue bswlist;
68 static void vm_hold_free_pages(struct buf * bp, vm_offset_t from,
70 static void vm_hold_load_pages(struct buf * bp, vm_offset_t from,
72 static void vfs_page_set_valid(struct buf *bp, vm_ooffset_t off,
73 int pageno, vm_page_t m);
74 static void vfs_clean_pages(struct buf * bp);
75 static void vfs_setdirty(struct buf *bp);
76 static void vfs_vmio_release(struct buf *bp);
78 static void vfs_backgroundwritedone(struct buf *bp);
80 static int flushbufqueues(void);
82 static int bd_request;
84 static void buf_daemon (void);
86 * bogus page -- for I/O to/from partially complete buffers
87 * this is a temporary solution to the problem, but it is not
88 * really that bad. it would be better to split the buffer
89 * for input in the case of buffers partially already in memory,
90 * but the code is intricate enough already.
93 int vmiodirenable = TRUE;
95 struct lwkt_token buftimetoken; /* Interlock on setting prio and timo */
97 static vm_offset_t bogus_offset;
99 static int bufspace, maxbufspace,
100 bufmallocspace, maxbufmallocspace, lobufspace, hibufspace;
101 static int bufreusecnt, bufdefragcnt, buffreekvacnt;
102 static int needsbuffer;
103 static int lorunningspace, hirunningspace, runningbufreq;
104 static int numdirtybuffers, lodirtybuffers, hidirtybuffers;
105 static int numfreebuffers, lofreebuffers, hifreebuffers;
106 static int getnewbufcalls;
107 static int getnewbufrestarts;
109 SYSCTL_INT(_vfs, OID_AUTO, numdirtybuffers, CTLFLAG_RD,
110 &numdirtybuffers, 0, "");
111 SYSCTL_INT(_vfs, OID_AUTO, lodirtybuffers, CTLFLAG_RW,
112 &lodirtybuffers, 0, "");
113 SYSCTL_INT(_vfs, OID_AUTO, hidirtybuffers, CTLFLAG_RW,
114 &hidirtybuffers, 0, "");
115 SYSCTL_INT(_vfs, OID_AUTO, numfreebuffers, CTLFLAG_RD,
116 &numfreebuffers, 0, "");
117 SYSCTL_INT(_vfs, OID_AUTO, lofreebuffers, CTLFLAG_RW,
118 &lofreebuffers, 0, "");
119 SYSCTL_INT(_vfs, OID_AUTO, hifreebuffers, CTLFLAG_RW,
120 &hifreebuffers, 0, "");
121 SYSCTL_INT(_vfs, OID_AUTO, runningbufspace, CTLFLAG_RD,
122 &runningbufspace, 0, "");
123 SYSCTL_INT(_vfs, OID_AUTO, lorunningspace, CTLFLAG_RW,
124 &lorunningspace, 0, "");
125 SYSCTL_INT(_vfs, OID_AUTO, hirunningspace, CTLFLAG_RW,
126 &hirunningspace, 0, "");
127 SYSCTL_INT(_vfs, OID_AUTO, maxbufspace, CTLFLAG_RD,
128 &maxbufspace, 0, "");
129 SYSCTL_INT(_vfs, OID_AUTO, hibufspace, CTLFLAG_RD,
131 SYSCTL_INT(_vfs, OID_AUTO, lobufspace, CTLFLAG_RD,
133 SYSCTL_INT(_vfs, OID_AUTO, bufspace, CTLFLAG_RD,
135 SYSCTL_INT(_vfs, OID_AUTO, maxmallocbufspace, CTLFLAG_RW,
136 &maxbufmallocspace, 0, "");
137 SYSCTL_INT(_vfs, OID_AUTO, bufmallocspace, CTLFLAG_RD,
138 &bufmallocspace, 0, "");
139 SYSCTL_INT(_vfs, OID_AUTO, getnewbufcalls, CTLFLAG_RW,
140 &getnewbufcalls, 0, "");
141 SYSCTL_INT(_vfs, OID_AUTO, getnewbufrestarts, CTLFLAG_RW,
142 &getnewbufrestarts, 0, "");
143 SYSCTL_INT(_vfs, OID_AUTO, vmiodirenable, CTLFLAG_RW,
144 &vmiodirenable, 0, "");
145 SYSCTL_INT(_vfs, OID_AUTO, bufdefragcnt, CTLFLAG_RW,
146 &bufdefragcnt, 0, "");
147 SYSCTL_INT(_vfs, OID_AUTO, buffreekvacnt, CTLFLAG_RW,
148 &buffreekvacnt, 0, "");
149 SYSCTL_INT(_vfs, OID_AUTO, bufreusecnt, CTLFLAG_RW,
150 &bufreusecnt, 0, "");
154 * Disable background writes for now. There appear to be races in the
155 * flags tests and locking operations as well as races in the completion
156 * code modifying the original bp (origbp) without holding a lock, assuming
157 * splbio protection when there might not be splbio protection.
159 * XXX disable also because the RB tree can't handle multiple blocks with
162 static int dobkgrdwrite = 0;
163 SYSCTL_INT(_debug, OID_AUTO, dobkgrdwrite, CTLFLAG_RW, &dobkgrdwrite, 0,
164 "Do background writes (honoring the BV_BKGRDWRITE flag)?");
167 static int bufhashmask;
168 static int bufhashshift;
169 static LIST_HEAD(bufhashhdr, buf) *bufhashtbl, invalhash;
170 struct bqueues bufqueues[BUFFER_QUEUES] = { { 0 } };
171 char *buf_wmesg = BUF_WMESG;
173 extern int vm_swap_size;
175 #define VFS_BIO_NEED_ANY 0x01 /* any freeable buffer */
176 #define VFS_BIO_NEED_DIRTYFLUSH 0x02 /* waiting for dirty buffer flush */
177 #define VFS_BIO_NEED_FREE 0x04 /* wait for free bufs, hi hysteresis */
178 #define VFS_BIO_NEED_BUFSPACE 0x08 /* wait for buf space, lo hysteresis */
181 * Buffer hash table code. Note that the logical block scans linearly, which
182 * gives us some L1 cache locality.
187 bufhash(struct vnode *vnp, daddr_t bn)
193 * A variation on the Fibonacci hash that Knuth credits to
194 * R. W. Floyd, see Knuth's _Art of Computer Programming,
195 * Volume 3 / Sorting and Searching_
197 * We reduce the argument to 32 bits before doing the hash to
198 * avoid the need for a slow 64x64 multiply on 32 bit platforms.
200 * sizeof(struct vnode) is 168 on i386, so toss some of the lower
201 * bits of the vnode address to reduce the key range, which
202 * improves the distribution of keys across buckets.
204 * The file system cylinder group blocks are very heavily
205 * used. They are located at invervals of fbg, which is
206 * on the order of 89 to 94 * 2^10, depending on other
207 * filesystem parameters, for a 16k block size. Smaller block
208 * sizes will reduce fpg approximately proportionally. This
209 * will cause the cylinder group index to be hashed using the
210 * lower bits of the hash multiplier, which will not distribute
211 * the keys as uniformly in a classic Fibonacci hash where a
212 * relatively small number of the upper bits of the result
213 * are used. Using 2^16 as a close-enough approximation to
214 * fpg, split the hash multiplier in half, with the upper 16
215 * bits being the inverse of the golden ratio, and the lower
216 * 16 bits being a fraction between 1/3 and 3/7 (closer to
217 * 3/7 in this case), that gives good experimental results.
219 hashkey64 = ((u_int64_t)(uintptr_t)vnp >> 3) + (u_int64_t)bn;
220 hashkey = (((u_int32_t)(hashkey64 + (hashkey64 >> 32)) * 0x9E376DB1u) >>
221 bufhashshift) & bufhashmask;
222 return(&bufhashtbl[hashkey]);
228 * If someone is blocked due to there being too many dirty buffers,
229 * and numdirtybuffers is now reasonable, wake them up.
233 numdirtywakeup(int level)
235 if (numdirtybuffers <= level) {
236 if (needsbuffer & VFS_BIO_NEED_DIRTYFLUSH) {
237 needsbuffer &= ~VFS_BIO_NEED_DIRTYFLUSH;
238 wakeup(&needsbuffer);
246 * Called when buffer space is potentially available for recovery.
247 * getnewbuf() will block on this flag when it is unable to free
248 * sufficient buffer space. Buffer space becomes recoverable when
249 * bp's get placed back in the queues.
256 * If someone is waiting for BUF space, wake them up. Even
257 * though we haven't freed the kva space yet, the waiting
258 * process will be able to now.
260 if (needsbuffer & VFS_BIO_NEED_BUFSPACE) {
261 needsbuffer &= ~VFS_BIO_NEED_BUFSPACE;
262 wakeup(&needsbuffer);
267 * runningbufwakeup() - in-progress I/O accounting.
271 runningbufwakeup(struct buf *bp)
273 if (bp->b_runningbufspace) {
274 runningbufspace -= bp->b_runningbufspace;
275 bp->b_runningbufspace = 0;
276 if (runningbufreq && runningbufspace <= lorunningspace) {
278 wakeup(&runningbufreq);
286 * Called when a buffer has been added to one of the free queues to
287 * account for the buffer and to wakeup anyone waiting for free buffers.
288 * This typically occurs when large amounts of metadata are being handled
289 * by the buffer cache ( else buffer space runs out first, usually ).
297 needsbuffer &= ~VFS_BIO_NEED_ANY;
298 if (numfreebuffers >= hifreebuffers)
299 needsbuffer &= ~VFS_BIO_NEED_FREE;
300 wakeup(&needsbuffer);
305 * waitrunningbufspace()
307 * runningbufspace is a measure of the amount of I/O currently
308 * running. This routine is used in async-write situations to
309 * prevent creating huge backups of pending writes to a device.
310 * Only asynchronous writes are governed by this function.
312 * Reads will adjust runningbufspace, but will not block based on it.
313 * The read load has a side effect of reducing the allowed write load.
315 * This does NOT turn an async write into a sync write. It waits
316 * for earlier writes to complete and generally returns before the
317 * caller's write has reached the device.
320 waitrunningbufspace(void)
322 while (runningbufspace > hirunningspace) {
325 s = splbio(); /* fix race against interrupt/biodone() */
327 tsleep(&runningbufreq, 0, "wdrain", 0);
333 * vfs_buf_test_cache:
335 * Called when a buffer is extended. This function clears the B_CACHE
336 * bit if the newly extended portion of the buffer does not contain
341 vfs_buf_test_cache(struct buf *bp,
342 vm_ooffset_t foff, vm_offset_t off, vm_offset_t size,
345 if (bp->b_flags & B_CACHE) {
346 int base = (foff + off) & PAGE_MASK;
347 if (vm_page_is_valid(m, base, size) == 0)
348 bp->b_flags &= ~B_CACHE;
354 bd_wakeup(int dirtybuflevel)
356 if (bd_request == 0 && numdirtybuffers >= dirtybuflevel) {
363 * bd_speedup - speedup the buffer cache flushing code
374 * Initialize buffer headers and related structures.
378 bufhashinit(caddr_t vaddr)
380 /* first, make a null hash table */
382 for (bufhashmask = 8; bufhashmask < nbuf / 4; bufhashmask <<= 1)
384 bufhashtbl = (void *)vaddr;
385 vaddr = vaddr + sizeof(*bufhashtbl) * bufhashmask;
396 TAILQ_INIT(&bswlist);
397 LIST_INIT(&invalhash);
398 lwkt_token_init(&buftimetoken);
400 for (i = 0; i <= bufhashmask; i++)
401 LIST_INIT(&bufhashtbl[i]);
403 /* next, make a null set of free lists */
404 for (i = 0; i < BUFFER_QUEUES; i++)
405 TAILQ_INIT(&bufqueues[i]);
407 /* finally, initialize each buffer header and stick on empty q */
408 for (i = 0; i < nbuf; i++) {
410 bzero(bp, sizeof *bp);
411 bp->b_flags = B_INVAL; /* we're just an empty header */
413 bp->b_qindex = QUEUE_EMPTY;
415 xio_init(&bp->b_xio);
416 LIST_INIT(&bp->b_dep);
418 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_EMPTY], bp, b_freelist);
419 LIST_INSERT_HEAD(&invalhash, bp, b_hash);
423 * maxbufspace is the absolute maximum amount of buffer space we are
424 * allowed to reserve in KVM and in real terms. The absolute maximum
425 * is nominally used by buf_daemon. hibufspace is the nominal maximum
426 * used by most other processes. The differential is required to
427 * ensure that buf_daemon is able to run when other processes might
428 * be blocked waiting for buffer space.
430 * maxbufspace is based on BKVASIZE. Allocating buffers larger then
431 * this may result in KVM fragmentation which is not handled optimally
434 maxbufspace = nbuf * BKVASIZE;
435 hibufspace = imax(3 * maxbufspace / 4, maxbufspace - MAXBSIZE * 10);
436 lobufspace = hibufspace - MAXBSIZE;
438 lorunningspace = 512 * 1024;
439 hirunningspace = 1024 * 1024;
442 * Limit the amount of malloc memory since it is wired permanently into
443 * the kernel space. Even though this is accounted for in the buffer
444 * allocation, we don't want the malloced region to grow uncontrolled.
445 * The malloc scheme improves memory utilization significantly on average
446 * (small) directories.
448 maxbufmallocspace = hibufspace / 20;
451 * Reduce the chance of a deadlock occuring by limiting the number
452 * of delayed-write dirty buffers we allow to stack up.
454 hidirtybuffers = nbuf / 4 + 20;
457 * To support extreme low-memory systems, make sure hidirtybuffers cannot
458 * eat up all available buffer space. This occurs when our minimum cannot
459 * be met. We try to size hidirtybuffers to 3/4 our buffer space assuming
460 * BKVASIZE'd (8K) buffers.
462 while (hidirtybuffers * BKVASIZE > 3 * hibufspace / 4) {
463 hidirtybuffers >>= 1;
465 lodirtybuffers = hidirtybuffers / 2;
468 * Try to keep the number of free buffers in the specified range,
469 * and give special processes (e.g. like buf_daemon) access to an
472 lofreebuffers = nbuf / 18 + 5;
473 hifreebuffers = 2 * lofreebuffers;
474 numfreebuffers = nbuf;
477 * Maximum number of async ops initiated per buf_daemon loop. This is
478 * somewhat of a hack at the moment, we really need to limit ourselves
479 * based on the number of bytes of I/O in-transit that were initiated
483 bogus_offset = kmem_alloc_pageable(kernel_map, PAGE_SIZE);
484 bogus_page = vm_page_alloc(kernel_object,
485 ((bogus_offset - VM_MIN_KERNEL_ADDRESS) >> PAGE_SHIFT),
487 vmstats.v_wire_count++;
492 * bfreekva() - free the kva allocation for a buffer.
494 * Must be called at splbio() or higher as this is the only locking for
497 * Since this call frees up buffer space, we call bufspacewakeup().
500 bfreekva(struct buf * bp)
506 count = vm_map_entry_reserve(MAP_RESERVE_COUNT);
507 vm_map_lock(buffer_map);
508 bufspace -= bp->b_kvasize;
509 vm_map_delete(buffer_map,
510 (vm_offset_t) bp->b_kvabase,
511 (vm_offset_t) bp->b_kvabase + bp->b_kvasize,
514 vm_map_unlock(buffer_map);
515 vm_map_entry_release(count);
524 * Remove the buffer from the appropriate free list.
527 bremfree(struct buf * bp)
530 int old_qindex = bp->b_qindex;
532 if (bp->b_qindex != QUEUE_NONE) {
533 KASSERT(BUF_REFCNTNB(bp) == 1,
534 ("bremfree: bp %p not locked",bp));
535 TAILQ_REMOVE(&bufqueues[bp->b_qindex], bp, b_freelist);
536 bp->b_qindex = QUEUE_NONE;
538 if (BUF_REFCNTNB(bp) <= 1)
539 panic("bremfree: removing a buffer not on a queue");
543 * Fixup numfreebuffers count. If the buffer is invalid or not
544 * delayed-write, and it was on the EMPTY, LRU, or AGE queues,
545 * the buffer was free and we must decrement numfreebuffers.
547 if ((bp->b_flags & B_INVAL) || (bp->b_flags & B_DELWRI) == 0) {
564 * Get a buffer with the specified data. Look in the cache first. We
565 * must clear B_ERROR and B_INVAL prior to initiating I/O. If B_CACHE
566 * is set, the buffer is valid and we do not have to do anything ( see
570 bread(struct vnode * vp, daddr_t blkno, int size, struct buf ** bpp)
574 bp = getblk(vp, blkno, size, 0, 0);
577 /* if not found in cache, do some I/O */
578 if ((bp->b_flags & B_CACHE) == 0) {
579 KASSERT(!(bp->b_flags & B_ASYNC), ("bread: illegal async bp %p", bp));
580 bp->b_flags |= B_READ;
581 bp->b_flags &= ~(B_ERROR | B_INVAL);
582 vfs_busy_pages(bp, 0);
583 VOP_STRATEGY(vp, bp);
584 return (biowait(bp));
590 * Operates like bread, but also starts asynchronous I/O on
591 * read-ahead blocks. We must clear B_ERROR and B_INVAL prior
592 * to initiating I/O . If B_CACHE is set, the buffer is valid
593 * and we do not have to do anything.
596 breadn(struct vnode * vp, daddr_t blkno, int size, daddr_t * rablkno,
597 int *rabsize, int cnt, struct buf ** bpp)
599 struct buf *bp, *rabp;
601 int rv = 0, readwait = 0;
603 *bpp = bp = getblk(vp, blkno, size, 0, 0);
605 /* if not found in cache, do some I/O */
606 if ((bp->b_flags & B_CACHE) == 0) {
607 bp->b_flags |= B_READ;
608 bp->b_flags &= ~(B_ERROR | B_INVAL);
609 vfs_busy_pages(bp, 0);
610 VOP_STRATEGY(vp, bp);
614 for (i = 0; i < cnt; i++, rablkno++, rabsize++) {
615 if (inmem(vp, *rablkno))
617 rabp = getblk(vp, *rablkno, *rabsize, 0, 0);
619 if ((rabp->b_flags & B_CACHE) == 0) {
620 rabp->b_flags |= B_READ | B_ASYNC;
621 rabp->b_flags &= ~(B_ERROR | B_INVAL);
622 vfs_busy_pages(rabp, 0);
624 VOP_STRATEGY(vp, rabp);
637 * Write, release buffer on completion. (Done by iodone
638 * if async). Do not bother writing anything if the buffer
641 * Note that we set B_CACHE here, indicating that buffer is
642 * fully valid and thus cacheable. This is true even of NFS
643 * now so we set it generally. This could be set either here
644 * or in biodone() since the I/O is synchronous. We put it
648 bwrite(struct buf * bp)
655 if (bp->b_flags & B_INVAL) {
660 oldflags = bp->b_flags;
662 if (BUF_REFCNTNB(bp) == 0)
663 panic("bwrite: buffer is not busy???");
666 * If a background write is already in progress, delay
667 * writing this block if it is asynchronous. Otherwise
668 * wait for the background write to complete.
670 if (bp->b_xflags & BX_BKGRDINPROG) {
671 if (bp->b_flags & B_ASYNC) {
676 bp->b_xflags |= BX_BKGRDWAIT;
677 tsleep(&bp->b_xflags, 0, "biord", 0);
678 if (bp->b_xflags & BX_BKGRDINPROG)
679 panic("bwrite: still writing");
682 /* Mark the buffer clean */
687 * If this buffer is marked for background writing and we
688 * do not have to wait for it, make a copy and write the
689 * copy so as to leave this buffer ready for further use.
691 * This optimization eats a lot of memory. If we have a page
692 * or buffer shortfull we can't do it.
694 * XXX DISABLED! This had to be removed to support the RB_TREE
695 * work and, really, this isn't the best place to do this sort
696 * of thing anyway. We really need a device copy-on-write feature.
699 (bp->b_xflags & BX_BKGRDWRITE) &&
700 (bp->b_flags & B_ASYNC) &&
701 !vm_page_count_severe() &&
702 !buf_dirty_count_severe()) {
703 if (bp->b_flags & B_CALL)
704 panic("bwrite: need chained iodone");
706 /* get a new block */
707 newbp = geteblk(bp->b_bufsize);
709 /* set it to be identical to the old block */
710 memcpy(newbp->b_data, bp->b_data, bp->b_bufsize);
711 newbp->b_lblkno = bp->b_lblkno;
712 newbp->b_blkno = bp->b_blkno;
713 newbp->b_offset = bp->b_offset;
714 newbp->b_iodone = vfs_backgroundwritedone;
715 newbp->b_flags |= B_ASYNC | B_CALL;
716 newbp->b_flags &= ~B_INVAL;
717 bgetvp(bp->b_vp, newbp);
719 /* move over the dependencies */
720 if (LIST_FIRST(&bp->b_dep) != NULL && bioops.io_movedeps)
721 (*bioops.io_movedeps)(bp, newbp);
724 * Initiate write on the copy, release the original to
725 * the B_LOCKED queue so that it cannot go away until
726 * the background write completes. If not locked it could go
727 * away and then be reconstituted while it was being written.
728 * If the reconstituted buffer were written, we could end up
729 * with two background copies being written at the same time.
731 bp->b_xflags |= BX_BKGRDINPROG;
732 bp->b_flags |= B_LOCKED;
738 bp->b_flags &= ~(B_READ | B_DONE | B_ERROR);
739 bp->b_flags |= B_CACHE;
741 bp->b_vp->v_numoutput++;
742 vfs_busy_pages(bp, 1);
745 * Normal bwrites pipeline writes
747 bp->b_runningbufspace = bp->b_bufsize;
748 runningbufspace += bp->b_runningbufspace;
751 if (oldflags & B_ASYNC)
753 VOP_STRATEGY(bp->b_vp, bp);
755 if ((oldflags & B_ASYNC) == 0) {
756 int rtval = biowait(bp);
759 } else if ((oldflags & B_NOWDRAIN) == 0) {
761 * don't allow the async write to saturate the I/O
762 * system. Deadlocks can occur only if a device strategy
763 * routine (like in VN) turns around and issues another
764 * high-level write, in which case B_NOWDRAIN is expected
765 * to be set. Otherwise we will not deadlock here because
766 * we are blocking waiting for I/O that is already in-progress
769 waitrunningbufspace();
777 * Complete a background write started from bwrite.
780 vfs_backgroundwritedone(struct buf *bp)
785 * Find the original buffer that we are writing.
787 if ((origbp = gbincore(bp->b_vp, bp->b_lblkno)) == NULL)
788 panic("backgroundwritedone: lost buffer");
790 * Process dependencies then return any unfinished ones.
792 if (LIST_FIRST(&bp->b_dep) != NULL && bioops.io_complete)
793 (*bioops.io_complete)(bp);
794 if (LIST_FIRST(&bp->b_dep) != NULL && bioops.io_movedeps)
795 (*bioops.io_movedeps)(bp, origbp);
797 * Clear the BX_BKGRDINPROG flag in the original buffer
798 * and awaken it if it is waiting for the write to complete.
799 * If BX_BKGRDINPROG is not set in the original buffer it must
800 * have been released and re-instantiated - which is not legal.
802 KASSERT((origbp->b_xflags & BX_BKGRDINPROG), ("backgroundwritedone: lost buffer2"));
803 origbp->b_xflags &= ~BX_BKGRDINPROG;
804 if (origbp->b_xflags & BX_BKGRDWAIT) {
805 origbp->b_xflags &= ~BX_BKGRDWAIT;
806 wakeup(&origbp->b_xflags);
809 * Clear the B_LOCKED flag and remove it from the locked
810 * queue if it currently resides there.
812 origbp->b_flags &= ~B_LOCKED;
813 if (BUF_LOCK(origbp, LK_EXCLUSIVE | LK_NOWAIT) == 0) {
818 * This buffer is marked B_NOCACHE, so when it is released
819 * by biodone, it will be tossed. We mark it with B_READ
820 * to avoid biodone doing a second vwakeup.
822 bp->b_flags |= B_NOCACHE | B_READ;
823 bp->b_flags &= ~(B_CACHE | B_CALL | B_DONE);
830 * Delayed write. (Buffer is marked dirty). Do not bother writing
831 * anything if the buffer is marked invalid.
833 * Note that since the buffer must be completely valid, we can safely
834 * set B_CACHE. In fact, we have to set B_CACHE here rather then in
835 * biodone() in order to prevent getblk from writing the buffer
839 bdwrite(struct buf *bp)
841 if (BUF_REFCNTNB(bp) == 0)
842 panic("bdwrite: buffer is not busy");
844 if (bp->b_flags & B_INVAL) {
851 * Set B_CACHE, indicating that the buffer is fully valid. This is
852 * true even of NFS now.
854 bp->b_flags |= B_CACHE;
857 * This bmap keeps the system from needing to do the bmap later,
858 * perhaps when the system is attempting to do a sync. Since it
859 * is likely that the indirect block -- or whatever other datastructure
860 * that the filesystem needs is still in memory now, it is a good
861 * thing to do this. Note also, that if the pageout daemon is
862 * requesting a sync -- there might not be enough memory to do
863 * the bmap then... So, this is important to do.
865 if (bp->b_lblkno == bp->b_blkno) {
866 VOP_BMAP(bp->b_vp, bp->b_lblkno, NULL, &bp->b_blkno, NULL, NULL);
870 * Set the *dirty* buffer range based upon the VM system dirty pages.
875 * We need to do this here to satisfy the vnode_pager and the
876 * pageout daemon, so that it thinks that the pages have been
877 * "cleaned". Note that since the pages are in a delayed write
878 * buffer -- the VFS layer "will" see that the pages get written
879 * out on the next sync, or perhaps the cluster will be completed.
885 * Wakeup the buffer flushing daemon if we have a lot of dirty
886 * buffers (midpoint between our recovery point and our stall
889 bd_wakeup((lodirtybuffers + hidirtybuffers) / 2);
892 * note: we cannot initiate I/O from a bdwrite even if we wanted to,
893 * due to the softdep code.
900 * Turn buffer into delayed write request. We must clear B_READ and
901 * B_RELBUF, and we must set B_DELWRI. We reassign the buffer to
902 * itself to properly update it in the dirty/clean lists. We mark it
903 * B_DONE to ensure that any asynchronization of the buffer properly
904 * clears B_DONE ( else a panic will occur later ).
906 * bdirty() is kinda like bdwrite() - we have to clear B_INVAL which
907 * might have been set pre-getblk(). Unlike bwrite/bdwrite, bdirty()
908 * should only be called if the buffer is known-good.
910 * Since the buffer is not on a queue, we do not update the numfreebuffers
913 * Must be called at splbio().
914 * The buffer must be on QUEUE_NONE.
917 bdirty(struct buf *bp)
919 KASSERT(bp->b_qindex == QUEUE_NONE, ("bdirty: buffer %p still on queue %d", bp, bp->b_qindex));
920 bp->b_flags &= ~(B_READ|B_RELBUF);
922 if ((bp->b_flags & B_DELWRI) == 0) {
923 bp->b_flags |= B_DONE | B_DELWRI;
924 reassignbuf(bp, bp->b_vp);
926 bd_wakeup((lodirtybuffers + hidirtybuffers) / 2);
933 * Clear B_DELWRI for buffer.
935 * Since the buffer is not on a queue, we do not update the numfreebuffers
938 * Must be called at splbio().
940 * The buffer is typically on QUEUE_NONE but there is one case in
941 * brelse() that calls this function after placing the buffer on
946 bundirty(struct buf *bp)
948 if (bp->b_flags & B_DELWRI) {
949 bp->b_flags &= ~B_DELWRI;
950 reassignbuf(bp, bp->b_vp);
952 numdirtywakeup(lodirtybuffers);
955 * Since it is now being written, we can clear its deferred write flag.
957 bp->b_flags &= ~B_DEFERRED;
963 * Asynchronous write. Start output on a buffer, but do not wait for
964 * it to complete. The buffer is released when the output completes.
966 * bwrite() ( or the VOP routine anyway ) is responsible for handling
967 * B_INVAL buffers. Not us.
970 bawrite(struct buf * bp)
972 bp->b_flags |= B_ASYNC;
973 (void) VOP_BWRITE(bp->b_vp, bp);
979 * Ordered write. Start output on a buffer, and flag it so that the
980 * device will write it in the order it was queued. The buffer is
981 * released when the output completes. bwrite() ( or the VOP routine
982 * anyway ) is responsible for handling B_INVAL buffers.
985 bowrite(struct buf * bp)
987 bp->b_flags |= B_ORDERED | B_ASYNC;
988 return (VOP_BWRITE(bp->b_vp, bp));
994 * Called prior to the locking of any vnodes when we are expecting to
995 * write. We do not want to starve the buffer cache with too many
996 * dirty buffers so we block here. By blocking prior to the locking
997 * of any vnodes we attempt to avoid the situation where a locked vnode
998 * prevents the various system daemons from flushing related buffers.
1004 if (numdirtybuffers >= hidirtybuffers) {
1008 while (numdirtybuffers >= hidirtybuffers) {
1010 needsbuffer |= VFS_BIO_NEED_DIRTYFLUSH;
1011 tsleep(&needsbuffer, 0, "flswai", 0);
1018 * Return true if we have too many dirty buffers.
1021 buf_dirty_count_severe(void)
1023 return(numdirtybuffers >= hidirtybuffers);
1029 * Release a busy buffer and, if requested, free its resources. The
1030 * buffer will be stashed in the appropriate bufqueue[] allowing it
1031 * to be accessed later as a cache entity or reused for other purposes.
1034 brelse(struct buf * bp)
1038 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)), ("brelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp));
1042 if (bp->b_flags & B_LOCKED)
1043 bp->b_flags &= ~B_ERROR;
1045 if ((bp->b_flags & (B_READ | B_ERROR | B_INVAL)) == B_ERROR) {
1047 * Failed write, redirty. Must clear B_ERROR to prevent
1048 * pages from being scrapped. If B_INVAL is set then
1049 * this case is not run and the next case is run to
1050 * destroy the buffer. B_INVAL can occur if the buffer
1051 * is outside the range supported by the underlying device.
1053 bp->b_flags &= ~B_ERROR;
1055 } else if ((bp->b_flags & (B_NOCACHE | B_INVAL | B_ERROR | B_FREEBUF)) ||
1056 (bp->b_bufsize <= 0)) {
1058 * Either a failed I/O or we were asked to free or not
1061 bp->b_flags |= B_INVAL;
1062 if (LIST_FIRST(&bp->b_dep) != NULL && bioops.io_deallocate)
1063 (*bioops.io_deallocate)(bp);
1064 if (bp->b_flags & B_DELWRI) {
1066 numdirtywakeup(lodirtybuffers);
1068 bp->b_flags &= ~(B_DELWRI | B_CACHE | B_FREEBUF);
1069 if ((bp->b_flags & B_VMIO) == 0) {
1078 * We must clear B_RELBUF if B_DELWRI is set. If vfs_vmio_release()
1079 * is called with B_DELWRI set, the underlying pages may wind up
1080 * getting freed causing a previous write (bdwrite()) to get 'lost'
1081 * because pages associated with a B_DELWRI bp are marked clean.
1083 * We still allow the B_INVAL case to call vfs_vmio_release(), even
1084 * if B_DELWRI is set.
1086 * If B_DELWRI is not set we may have to set B_RELBUF if we are low
1087 * on pages to return pages to the VM page queues.
1089 if (bp->b_flags & B_DELWRI)
1090 bp->b_flags &= ~B_RELBUF;
1091 else if (vm_page_count_severe() && !(bp->b_xflags & BX_BKGRDINPROG))
1092 bp->b_flags |= B_RELBUF;
1095 * VMIO buffer rundown. It is not very necessary to keep a VMIO buffer
1096 * constituted, not even NFS buffers now. Two flags effect this. If
1097 * B_INVAL, the struct buf is invalidated but the VM object is kept
1098 * around ( i.e. so it is trivial to reconstitute the buffer later ).
1100 * If B_ERROR or B_NOCACHE is set, pages in the VM object will be
1101 * invalidated. B_ERROR cannot be set for a failed write unless the
1102 * buffer is also B_INVAL because it hits the re-dirtying code above.
1104 * Normally we can do this whether a buffer is B_DELWRI or not. If
1105 * the buffer is an NFS buffer, it is tracking piecemeal writes or
1106 * the commit state and we cannot afford to lose the buffer. If the
1107 * buffer has a background write in progress, we need to keep it
1108 * around to prevent it from being reconstituted and starting a second
1111 if ((bp->b_flags & B_VMIO)
1112 && !(bp->b_vp->v_tag == VT_NFS &&
1113 !vn_isdisk(bp->b_vp, NULL) &&
1114 (bp->b_flags & B_DELWRI))
1127 * Get the base offset and length of the buffer. Note that
1128 * in the VMIO case if the buffer block size is not
1129 * page-aligned then b_data pointer may not be page-aligned.
1130 * But our b_xio.xio_pages array *IS* page aligned.
1132 * block sizes less then DEV_BSIZE (usually 512) are not
1133 * supported due to the page granularity bits (m->valid,
1134 * m->dirty, etc...).
1136 * See man buf(9) for more information
1139 resid = bp->b_bufsize;
1140 foff = bp->b_offset;
1142 for (i = 0; i < bp->b_xio.xio_npages; i++) {
1143 m = bp->b_xio.xio_pages[i];
1144 vm_page_flag_clear(m, PG_ZERO);
1146 * If we hit a bogus page, fixup *all* of them
1147 * now. Note that we left these pages wired
1148 * when we removed them so they had better exist,
1149 * and they cannot be ripped out from under us so
1150 * no splvm() protection is necessary.
1152 if (m == bogus_page) {
1153 VOP_GETVOBJECT(vp, &obj);
1154 poff = OFF_TO_IDX(bp->b_offset);
1156 for (j = i; j < bp->b_xio.xio_npages; j++) {
1159 mtmp = bp->b_xio.xio_pages[j];
1160 if (mtmp == bogus_page) {
1161 mtmp = vm_page_lookup(obj, poff + j);
1163 panic("brelse: page missing");
1165 bp->b_xio.xio_pages[j] = mtmp;
1169 if ((bp->b_flags & B_INVAL) == 0) {
1170 pmap_qenter(trunc_page((vm_offset_t)bp->b_data),
1171 bp->b_xio.xio_pages, bp->b_xio.xio_npages);
1173 m = bp->b_xio.xio_pages[i];
1177 * Invalidate the backing store if B_NOCACHE is set
1178 * (e.g. used with vinvalbuf()). If this is NFS
1179 * we impose a requirement that the block size be
1180 * a multiple of PAGE_SIZE and create a temporary
1181 * hack to basically invalidate the whole page. The
1182 * problem is that NFS uses really odd buffer sizes
1183 * especially when tracking piecemeal writes and
1184 * it also vinvalbuf()'s a lot, which would result
1185 * in only partial page validation and invalidation
1186 * here. If the file page is mmap()'d, however,
1187 * all the valid bits get set so after we invalidate
1188 * here we would end up with weird m->valid values
1189 * like 0xfc. nfs_getpages() can't handle this so
1190 * we clear all the valid bits for the NFS case
1191 * instead of just some of them.
1193 * The real bug is the VM system having to set m->valid
1194 * to VM_PAGE_BITS_ALL for faulted-in pages, which
1195 * itself is an artifact of the whole 512-byte
1196 * granular mess that exists to support odd block
1197 * sizes and UFS meta-data block sizes (e.g. 6144).
1198 * A complete rewrite is required.
1200 if (bp->b_flags & (B_NOCACHE|B_ERROR)) {
1201 int poffset = foff & PAGE_MASK;
1204 presid = PAGE_SIZE - poffset;
1205 if (bp->b_vp->v_tag == VT_NFS &&
1206 bp->b_vp->v_type == VREG) {
1208 } else if (presid > resid) {
1211 KASSERT(presid >= 0, ("brelse: extra page"));
1212 vm_page_set_invalid(m, poffset, presid);
1214 resid -= PAGE_SIZE - (foff & PAGE_MASK);
1215 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK;
1218 if (bp->b_flags & (B_INVAL | B_RELBUF))
1219 vfs_vmio_release(bp);
1221 } else if (bp->b_flags & B_VMIO) {
1223 if (bp->b_flags & (B_INVAL | B_RELBUF))
1224 vfs_vmio_release(bp);
1228 if (bp->b_qindex != QUEUE_NONE)
1229 panic("brelse: free buffer onto another queue???");
1230 if (BUF_REFCNTNB(bp) > 1) {
1231 /* Temporary panic to verify exclusive locking */
1232 /* This panic goes away when we allow shared refs */
1233 panic("brelse: multiple refs");
1234 /* do not release to free list */
1242 /* buffers with no memory */
1243 if (bp->b_bufsize == 0) {
1244 bp->b_flags |= B_INVAL;
1245 bp->b_xflags &= ~BX_BKGRDWRITE;
1246 if (bp->b_xflags & BX_BKGRDINPROG)
1247 panic("losing buffer 1");
1248 if (bp->b_kvasize) {
1249 bp->b_qindex = QUEUE_EMPTYKVA;
1251 bp->b_qindex = QUEUE_EMPTY;
1253 TAILQ_INSERT_HEAD(&bufqueues[bp->b_qindex], bp, b_freelist);
1254 LIST_REMOVE(bp, b_hash);
1255 LIST_INSERT_HEAD(&invalhash, bp, b_hash);
1257 /* buffers with junk contents */
1258 } else if (bp->b_flags & (B_ERROR | B_INVAL | B_NOCACHE | B_RELBUF)) {
1259 bp->b_flags |= B_INVAL;
1260 bp->b_xflags &= ~BX_BKGRDWRITE;
1261 if (bp->b_xflags & BX_BKGRDINPROG)
1262 panic("losing buffer 2");
1263 bp->b_qindex = QUEUE_CLEAN;
1264 TAILQ_INSERT_HEAD(&bufqueues[QUEUE_CLEAN], bp, b_freelist);
1265 LIST_REMOVE(bp, b_hash);
1266 LIST_INSERT_HEAD(&invalhash, bp, b_hash);
1269 /* buffers that are locked */
1270 } else if (bp->b_flags & B_LOCKED) {
1271 bp->b_qindex = QUEUE_LOCKED;
1272 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_LOCKED], bp, b_freelist);
1274 /* remaining buffers */
1276 switch(bp->b_flags & (B_DELWRI|B_AGE)) {
1277 case B_DELWRI | B_AGE:
1278 bp->b_qindex = QUEUE_DIRTY;
1279 TAILQ_INSERT_HEAD(&bufqueues[QUEUE_DIRTY], bp, b_freelist);
1282 bp->b_qindex = QUEUE_DIRTY;
1283 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_DIRTY], bp, b_freelist);
1286 bp->b_qindex = QUEUE_CLEAN;
1287 TAILQ_INSERT_HEAD(&bufqueues[QUEUE_CLEAN], bp, b_freelist);
1290 bp->b_qindex = QUEUE_CLEAN;
1291 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_CLEAN], bp, b_freelist);
1297 * If B_INVAL, clear B_DELWRI. We've already placed the buffer
1298 * on the correct queue.
1300 if ((bp->b_flags & (B_INVAL|B_DELWRI)) == (B_INVAL|B_DELWRI))
1304 * Fixup numfreebuffers count. The bp is on an appropriate queue
1305 * unless locked. We then bump numfreebuffers if it is not B_DELWRI.
1306 * We've already handled the B_INVAL case ( B_DELWRI will be clear
1307 * if B_INVAL is set ).
1310 if ((bp->b_flags & B_LOCKED) == 0 && !(bp->b_flags & B_DELWRI))
1314 * Something we can maybe free or reuse
1316 if (bp->b_bufsize || bp->b_kvasize)
1321 bp->b_flags &= ~(B_ORDERED | B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF |
1322 B_DIRECT | B_NOWDRAIN);
1327 * Release a buffer back to the appropriate queue but do not try to free
1328 * it. The buffer is expected to be used again soon.
1330 * bqrelse() is used by bdwrite() to requeue a delayed write, and used by
1331 * biodone() to requeue an async I/O on completion. It is also used when
1332 * known good buffers need to be requeued but we think we may need the data
1335 * XXX we should be able to leave the B_RELBUF hint set on completion.
1338 bqrelse(struct buf * bp)
1344 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)), ("bqrelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp));
1346 if (bp->b_qindex != QUEUE_NONE)
1347 panic("bqrelse: free buffer onto another queue???");
1348 if (BUF_REFCNTNB(bp) > 1) {
1349 /* do not release to free list */
1350 panic("bqrelse: multiple refs");
1355 if (bp->b_flags & B_LOCKED) {
1356 bp->b_flags &= ~B_ERROR;
1357 bp->b_qindex = QUEUE_LOCKED;
1358 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_LOCKED], bp, b_freelist);
1359 /* buffers with stale but valid contents */
1360 } else if (bp->b_flags & B_DELWRI) {
1361 bp->b_qindex = QUEUE_DIRTY;
1362 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_DIRTY], bp, b_freelist);
1363 } else if (vm_page_count_severe()) {
1365 * We are too low on memory, we have to try to free the
1366 * buffer (most importantly: the wired pages making up its
1367 * backing store) *now*.
1373 bp->b_qindex = QUEUE_CLEAN;
1374 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_CLEAN], bp, b_freelist);
1377 if ((bp->b_flags & B_LOCKED) == 0 &&
1378 ((bp->b_flags & B_INVAL) || !(bp->b_flags & B_DELWRI))) {
1383 * Something we can maybe free or reuse.
1385 if (bp->b_bufsize && !(bp->b_flags & B_DELWRI))
1390 bp->b_flags &= ~(B_ORDERED | B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF);
1395 vfs_vmio_release(struct buf *bp)
1401 for (i = 0; i < bp->b_xio.xio_npages; i++) {
1402 m = bp->b_xio.xio_pages[i];
1403 bp->b_xio.xio_pages[i] = NULL;
1405 * In order to keep page LRU ordering consistent, put
1406 * everything on the inactive queue.
1408 vm_page_unwire(m, 0);
1410 * We don't mess with busy pages, it is
1411 * the responsibility of the process that
1412 * busied the pages to deal with them.
1414 if ((m->flags & PG_BUSY) || (m->busy != 0))
1417 if (m->wire_count == 0) {
1418 vm_page_flag_clear(m, PG_ZERO);
1420 * Might as well free the page if we can and it has
1421 * no valid data. We also free the page if the
1422 * buffer was used for direct I/O.
1424 if ((bp->b_flags & B_ASYNC) == 0 && !m->valid && m->hold_count == 0) {
1426 vm_page_protect(m, VM_PROT_NONE);
1428 } else if (bp->b_flags & B_DIRECT) {
1429 vm_page_try_to_free(m);
1430 } else if (vm_page_count_severe()) {
1431 vm_page_try_to_cache(m);
1436 pmap_qremove(trunc_page((vm_offset_t) bp->b_data), bp->b_xio.xio_npages);
1437 if (bp->b_bufsize) {
1441 bp->b_xio.xio_npages = 0;
1442 bp->b_flags &= ~B_VMIO;
1448 * Check to see if a block is currently memory resident.
1451 gbincore(struct vnode * vp, daddr_t blkno)
1454 struct bufhashhdr *bh;
1456 bh = bufhash(vp, blkno);
1458 /* Search hash chain */
1459 LIST_FOREACH(bp, bh, b_hash) {
1461 if (bp->b_vp == vp && bp->b_lblkno == blkno &&
1462 (bp->b_flags & B_INVAL) == 0) {
1472 * Implement clustered async writes for clearing out B_DELWRI buffers.
1473 * This is much better then the old way of writing only one buffer at
1474 * a time. Note that we may not be presented with the buffers in the
1475 * correct order, so we search for the cluster in both directions.
1478 vfs_bio_awrite(struct buf * bp)
1482 daddr_t lblkno = bp->b_lblkno;
1483 struct vnode *vp = bp->b_vp;
1493 * right now we support clustered writing only to regular files. If
1494 * we find a clusterable block we could be in the middle of a cluster
1495 * rather then at the beginning.
1497 if ((vp->v_type == VREG) &&
1498 (vp->v_mount != 0) && /* Only on nodes that have the size info */
1499 (bp->b_flags & (B_CLUSTEROK | B_INVAL)) == B_CLUSTEROK) {
1501 size = vp->v_mount->mnt_stat.f_iosize;
1502 maxcl = MAXPHYS / size;
1504 for (i = 1; i < maxcl; i++) {
1505 if ((bpa = gbincore(vp, lblkno + i)) &&
1506 BUF_REFCNT(bpa) == 0 &&
1507 ((bpa->b_flags & (B_DELWRI | B_CLUSTEROK | B_INVAL)) ==
1508 (B_DELWRI | B_CLUSTEROK)) &&
1509 (bpa->b_bufsize == size)) {
1510 if ((bpa->b_blkno == bpa->b_lblkno) ||
1512 bp->b_blkno + ((i * size) >> DEV_BSHIFT)))
1518 for (j = 1; i + j <= maxcl && j <= lblkno; j++) {
1519 if ((bpa = gbincore(vp, lblkno - j)) &&
1520 BUF_REFCNT(bpa) == 0 &&
1521 ((bpa->b_flags & (B_DELWRI | B_CLUSTEROK | B_INVAL)) ==
1522 (B_DELWRI | B_CLUSTEROK)) &&
1523 (bpa->b_bufsize == size)) {
1524 if ((bpa->b_blkno == bpa->b_lblkno) ||
1526 bp->b_blkno - ((j * size) >> DEV_BSHIFT)))
1535 * this is a possible cluster write
1538 nwritten = cluster_wbuild(vp, size, lblkno - j, ncl);
1544 BUF_LOCK(bp, LK_EXCLUSIVE);
1546 bp->b_flags |= B_ASYNC;
1550 * default (old) behavior, writing out only one block
1552 * XXX returns b_bufsize instead of b_bcount for nwritten?
1554 nwritten = bp->b_bufsize;
1555 (void) VOP_BWRITE(bp->b_vp, bp);
1563 * Find and initialize a new buffer header, freeing up existing buffers
1564 * in the bufqueues as necessary. The new buffer is returned locked.
1566 * Important: B_INVAL is not set. If the caller wishes to throw the
1567 * buffer away, the caller must set B_INVAL prior to calling brelse().
1570 * We have insufficient buffer headers
1571 * We have insufficient buffer space
1572 * buffer_map is too fragmented ( space reservation fails )
1573 * If we have to flush dirty buffers ( but we try to avoid this )
1575 * To avoid VFS layer recursion we do not flush dirty buffers ourselves.
1576 * Instead we ask the buf daemon to do it for us. We attempt to
1577 * avoid piecemeal wakeups of the pageout daemon.
1581 getnewbuf(int slpflag, int slptimeo, int size, int maxsize)
1587 static int flushingbufs;
1590 * We can't afford to block since we might be holding a vnode lock,
1591 * which may prevent system daemons from running. We deal with
1592 * low-memory situations by proactively returning memory and running
1593 * async I/O rather then sync I/O.
1597 --getnewbufrestarts;
1599 ++getnewbufrestarts;
1602 * Setup for scan. If we do not have enough free buffers,
1603 * we setup a degenerate case that immediately fails. Note
1604 * that if we are specially marked process, we are allowed to
1605 * dip into our reserves.
1607 * The scanning sequence is nominally: EMPTY->EMPTYKVA->CLEAN
1609 * We start with EMPTYKVA. If the list is empty we backup to EMPTY.
1610 * However, there are a number of cases (defragging, reusing, ...)
1611 * where we cannot backup.
1613 nqindex = QUEUE_EMPTYKVA;
1614 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTYKVA]);
1618 * If no EMPTYKVA buffers and we are either
1619 * defragging or reusing, locate a CLEAN buffer
1620 * to free or reuse. If bufspace useage is low
1621 * skip this step so we can allocate a new buffer.
1623 if (defrag || bufspace >= lobufspace) {
1624 nqindex = QUEUE_CLEAN;
1625 nbp = TAILQ_FIRST(&bufqueues[QUEUE_CLEAN]);
1629 * If we could not find or were not allowed to reuse a
1630 * CLEAN buffer, check to see if it is ok to use an EMPTY
1631 * buffer. We can only use an EMPTY buffer if allocating
1632 * its KVA would not otherwise run us out of buffer space.
1634 if (nbp == NULL && defrag == 0 &&
1635 bufspace + maxsize < hibufspace) {
1636 nqindex = QUEUE_EMPTY;
1637 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTY]);
1642 * Run scan, possibly freeing data and/or kva mappings on the fly
1646 while ((bp = nbp) != NULL) {
1647 int qindex = nqindex;
1650 * Calculate next bp ( we can only use it if we do not block
1651 * or do other fancy things ).
1653 if ((nbp = TAILQ_NEXT(bp, b_freelist)) == NULL) {
1656 nqindex = QUEUE_EMPTYKVA;
1657 if ((nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTYKVA])))
1660 case QUEUE_EMPTYKVA:
1661 nqindex = QUEUE_CLEAN;
1662 if ((nbp = TAILQ_FIRST(&bufqueues[QUEUE_CLEAN])))
1676 KASSERT(bp->b_qindex == qindex, ("getnewbuf: inconsistant queue %d bp %p", qindex, bp));
1679 * Note: we no longer distinguish between VMIO and non-VMIO
1683 KASSERT((bp->b_flags & B_DELWRI) == 0, ("delwri buffer %p found in queue %d", bp, qindex));
1686 * If we are defragging then we need a buffer with
1687 * b_kvasize != 0. XXX this situation should no longer
1688 * occur, if defrag is non-zero the buffer's b_kvasize
1689 * should also be non-zero at this point. XXX
1691 if (defrag && bp->b_kvasize == 0) {
1692 printf("Warning: defrag empty buffer %p\n", bp);
1697 * Start freeing the bp. This is somewhat involved. nbp
1698 * remains valid only for QUEUE_EMPTY[KVA] bp's.
1701 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT) != 0)
1702 panic("getnewbuf: locked buf");
1705 if (qindex == QUEUE_CLEAN) {
1706 if (bp->b_flags & B_VMIO) {
1707 bp->b_flags &= ~B_ASYNC;
1708 vfs_vmio_release(bp);
1715 * NOTE: nbp is now entirely invalid. We can only restart
1716 * the scan from this point on.
1718 * Get the rest of the buffer freed up. b_kva* is still
1719 * valid after this operation.
1722 if (LIST_FIRST(&bp->b_dep) != NULL && bioops.io_deallocate)
1723 (*bioops.io_deallocate)(bp);
1724 if (bp->b_xflags & BX_BKGRDINPROG)
1725 panic("losing buffer 3");
1726 LIST_REMOVE(bp, b_hash);
1727 LIST_INSERT_HEAD(&invalhash, bp, b_hash);
1730 * spl protection not required when scrapping a buffer's
1731 * contents because it is already wired.
1740 bp->b_blkno = bp->b_lblkno = 0;
1741 bp->b_offset = NOOFFSET;
1746 bp->b_xio.xio_npages = 0;
1747 bp->b_dirtyoff = bp->b_dirtyend = 0;
1749 LIST_INIT(&bp->b_dep);
1752 * If we are defragging then free the buffer.
1755 bp->b_flags |= B_INVAL;
1763 * If we are overcomitted then recover the buffer and its
1764 * KVM space. This occurs in rare situations when multiple
1765 * processes are blocked in getnewbuf() or allocbuf().
1767 if (bufspace >= hibufspace)
1769 if (flushingbufs && bp->b_kvasize != 0) {
1770 bp->b_flags |= B_INVAL;
1775 if (bufspace < lobufspace)
1781 * If we exhausted our list, sleep as appropriate. We may have to
1782 * wakeup various daemons and write out some dirty buffers.
1784 * Generally we are sleeping due to insufficient buffer space.
1792 flags = VFS_BIO_NEED_BUFSPACE;
1794 } else if (bufspace >= hibufspace) {
1796 flags = VFS_BIO_NEED_BUFSPACE;
1799 flags = VFS_BIO_NEED_ANY;
1802 bd_speedup(); /* heeeelp */
1804 needsbuffer |= flags;
1805 while (needsbuffer & flags) {
1806 if (tsleep(&needsbuffer, slpflag, waitmsg, slptimeo))
1811 * We finally have a valid bp. We aren't quite out of the
1812 * woods, we still have to reserve kva space. In order
1813 * to keep fragmentation sane we only allocate kva in
1816 maxsize = (maxsize + BKVAMASK) & ~BKVAMASK;
1818 if (maxsize != bp->b_kvasize) {
1819 vm_offset_t addr = 0;
1824 count = vm_map_entry_reserve(MAP_RESERVE_COUNT);
1825 vm_map_lock(buffer_map);
1827 if (vm_map_findspace(buffer_map,
1828 vm_map_min(buffer_map), maxsize,
1831 * Uh oh. Buffer map is to fragmented. We
1832 * must defragment the map.
1834 vm_map_unlock(buffer_map);
1835 vm_map_entry_release(count);
1838 bp->b_flags |= B_INVAL;
1843 vm_map_insert(buffer_map, &count,
1845 addr, addr + maxsize,
1846 VM_PROT_ALL, VM_PROT_ALL, MAP_NOFAULT);
1848 bp->b_kvabase = (caddr_t) addr;
1849 bp->b_kvasize = maxsize;
1850 bufspace += bp->b_kvasize;
1853 vm_map_unlock(buffer_map);
1854 vm_map_entry_release(count);
1856 bp->b_data = bp->b_kvabase;
1864 * buffer flushing daemon. Buffers are normally flushed by the
1865 * update daemon but if it cannot keep up this process starts to
1866 * take the load in an attempt to prevent getnewbuf() from blocking.
1869 static struct thread *bufdaemonthread;
1871 static struct kproc_desc buf_kp = {
1876 SYSINIT(bufdaemon, SI_SUB_KTHREAD_BUF, SI_ORDER_FIRST, kproc_start, &buf_kp)
1884 * This process needs to be suspended prior to shutdown sync.
1886 EVENTHANDLER_REGISTER(shutdown_pre_sync, shutdown_kproc,
1887 bufdaemonthread, SHUTDOWN_PRI_LAST);
1890 * This process is allowed to take the buffer cache to the limit
1895 kproc_suspend_loop();
1898 * Do the flush. Limit the amount of in-transit I/O we
1899 * allow to build up, otherwise we would completely saturate
1900 * the I/O system. Wakeup any waiting processes before we
1901 * normally would so they can run in parallel with our drain.
1903 while (numdirtybuffers > lodirtybuffers) {
1904 if (flushbufqueues() == 0)
1906 waitrunningbufspace();
1907 numdirtywakeup((lodirtybuffers + hidirtybuffers) / 2);
1911 * Only clear bd_request if we have reached our low water
1912 * mark. The buf_daemon normally waits 5 seconds and
1913 * then incrementally flushes any dirty buffers that have
1914 * built up, within reason.
1916 * If we were unable to hit our low water mark and couldn't
1917 * find any flushable buffers, we sleep half a second.
1918 * Otherwise we loop immediately.
1920 if (numdirtybuffers <= lodirtybuffers) {
1922 * We reached our low water mark, reset the
1923 * request and sleep until we are needed again.
1924 * The sleep is just so the suspend code works.
1927 tsleep(&bd_request, 0, "psleep", hz);
1930 * We couldn't find any flushable dirty buffers but
1931 * still have too many dirty buffers, we
1932 * have to sleep and try again. (rare)
1934 tsleep(&bd_request, 0, "qsleep", hz / 2);
1942 * Try to flush a buffer in the dirty queue. We must be careful to
1943 * free up B_INVAL buffers instead of write them, which NFS is
1944 * particularly sensitive to.
1948 flushbufqueues(void)
1953 bp = TAILQ_FIRST(&bufqueues[QUEUE_DIRTY]);
1956 KASSERT((bp->b_flags & B_DELWRI), ("unexpected clean buffer %p", bp));
1957 if ((bp->b_flags & B_DELWRI) != 0 &&
1958 (bp->b_xflags & BX_BKGRDINPROG) == 0) {
1959 if (bp->b_flags & B_INVAL) {
1960 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT) != 0)
1961 panic("flushbufqueues: locked buf");
1967 if (LIST_FIRST(&bp->b_dep) != NULL &&
1968 bioops.io_countdeps &&
1969 (bp->b_flags & B_DEFERRED) == 0 &&
1970 (*bioops.io_countdeps)(bp, 0)) {
1971 TAILQ_REMOVE(&bufqueues[QUEUE_DIRTY],
1973 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_DIRTY],
1975 bp->b_flags |= B_DEFERRED;
1976 bp = TAILQ_FIRST(&bufqueues[QUEUE_DIRTY]);
1983 bp = TAILQ_NEXT(bp, b_freelist);
1989 * Check to see if a block is currently memory resident.
1992 incore(struct vnode * vp, daddr_t blkno)
1997 bp = gbincore(vp, blkno);
2003 * Returns true if no I/O is needed to access the associated VM object.
2004 * This is like incore except it also hunts around in the VM system for
2007 * Note that we ignore vm_page_free() races from interrupts against our
2008 * lookup, since if the caller is not protected our return value will not
2009 * be any more valid then otherwise once we splx().
2012 inmem(struct vnode * vp, daddr_t blkno)
2015 vm_offset_t toff, tinc, size;
2019 if (incore(vp, blkno))
2021 if (vp->v_mount == NULL)
2023 if (VOP_GETVOBJECT(vp, &obj) != 0 || (vp->v_flag & VOBJBUF) == 0)
2027 if (size > vp->v_mount->mnt_stat.f_iosize)
2028 size = vp->v_mount->mnt_stat.f_iosize;
2029 off = (vm_ooffset_t)blkno * (vm_ooffset_t)vp->v_mount->mnt_stat.f_iosize;
2031 for (toff = 0; toff < vp->v_mount->mnt_stat.f_iosize; toff += tinc) {
2032 m = vm_page_lookup(obj, OFF_TO_IDX(off + toff));
2036 if (tinc > PAGE_SIZE - ((toff + off) & PAGE_MASK))
2037 tinc = PAGE_SIZE - ((toff + off) & PAGE_MASK);
2038 if (vm_page_is_valid(m,
2039 (vm_offset_t) ((toff + off) & PAGE_MASK), tinc) == 0)
2048 * Sets the dirty range for a buffer based on the status of the dirty
2049 * bits in the pages comprising the buffer.
2051 * The range is limited to the size of the buffer.
2053 * This routine is primarily used by NFS, but is generalized for the
2057 vfs_setdirty(struct buf *bp)
2063 * Degenerate case - empty buffer
2066 if (bp->b_bufsize == 0)
2070 * We qualify the scan for modified pages on whether the
2071 * object has been flushed yet. The OBJ_WRITEABLE flag
2072 * is not cleared simply by protecting pages off.
2075 if ((bp->b_flags & B_VMIO) == 0)
2078 object = bp->b_xio.xio_pages[0]->object;
2080 if ((object->flags & OBJ_WRITEABLE) && !(object->flags & OBJ_MIGHTBEDIRTY))
2081 printf("Warning: object %p writeable but not mightbedirty\n", object);
2082 if (!(object->flags & OBJ_WRITEABLE) && (object->flags & OBJ_MIGHTBEDIRTY))
2083 printf("Warning: object %p mightbedirty but not writeable\n", object);
2085 if (object->flags & (OBJ_MIGHTBEDIRTY|OBJ_CLEANING)) {
2086 vm_offset_t boffset;
2087 vm_offset_t eoffset;
2090 * test the pages to see if they have been modified directly
2091 * by users through the VM system.
2093 for (i = 0; i < bp->b_xio.xio_npages; i++) {
2094 vm_page_flag_clear(bp->b_xio.xio_pages[i], PG_ZERO);
2095 vm_page_test_dirty(bp->b_xio.xio_pages[i]);
2099 * Calculate the encompassing dirty range, boffset and eoffset,
2100 * (eoffset - boffset) bytes.
2103 for (i = 0; i < bp->b_xio.xio_npages; i++) {
2104 if (bp->b_xio.xio_pages[i]->dirty)
2107 boffset = (i << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK);
2109 for (i = bp->b_xio.xio_npages - 1; i >= 0; --i) {
2110 if (bp->b_xio.xio_pages[i]->dirty) {
2114 eoffset = ((i + 1) << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK);
2117 * Fit it to the buffer.
2120 if (eoffset > bp->b_bcount)
2121 eoffset = bp->b_bcount;
2124 * If we have a good dirty range, merge with the existing
2128 if (boffset < eoffset) {
2129 if (bp->b_dirtyoff > boffset)
2130 bp->b_dirtyoff = boffset;
2131 if (bp->b_dirtyend < eoffset)
2132 bp->b_dirtyend = eoffset;
2140 * Get a block given a specified block and offset into a file/device.
2141 * The buffers B_DONE bit will be cleared on return, making it almost
2142 * ready for an I/O initiation. B_INVAL may or may not be set on
2143 * return. The caller should clear B_INVAL prior to initiating a
2146 * IT IS IMPORTANT TO UNDERSTAND THAT IF YOU CALL GETBLK() AND B_CACHE
2147 * IS NOT SET, YOU MUST INITIALIZE THE RETURNED BUFFER, ISSUE A READ,
2148 * OR SET B_INVAL BEFORE RETIRING IT. If you retire a getblk'd buffer
2149 * without doing any of those things the system will likely believe
2150 * the buffer to be valid (especially if it is not B_VMIO), and the
2151 * next getblk() will return the buffer with B_CACHE set.
2153 * For a non-VMIO buffer, B_CACHE is set to the opposite of B_INVAL for
2154 * an existing buffer.
2156 * For a VMIO buffer, B_CACHE is modified according to the backing VM.
2157 * If getblk()ing a previously 0-sized invalid buffer, B_CACHE is set
2158 * and then cleared based on the backing VM. If the previous buffer is
2159 * non-0-sized but invalid, B_CACHE will be cleared.
2161 * If getblk() must create a new buffer, the new buffer is returned with
2162 * both B_INVAL and B_CACHE clear unless it is a VMIO buffer, in which
2163 * case it is returned with B_INVAL clear and B_CACHE set based on the
2166 * getblk() also forces a VOP_BWRITE() for any B_DELWRI buffer whos
2167 * B_CACHE bit is clear.
2169 * What this means, basically, is that the caller should use B_CACHE to
2170 * determine whether the buffer is fully valid or not and should clear
2171 * B_INVAL prior to issuing a read. If the caller intends to validate
2172 * the buffer by loading its data area with something, the caller needs
2173 * to clear B_INVAL. If the caller does this without issuing an I/O,
2174 * the caller should set B_CACHE ( as an optimization ), else the caller
2175 * should issue the I/O and biodone() will set B_CACHE if the I/O was
2176 * a write attempt or if it was a successfull read. If the caller
2177 * intends to issue a READ, the caller must clear B_INVAL and B_ERROR
2178 * prior to issuing the READ. biodone() will *not* clear B_INVAL.
2181 getblk(struct vnode * vp, daddr_t blkno, int size, int slpflag, int slptimeo)
2185 struct bufhashhdr *bh;
2187 if (size > MAXBSIZE)
2188 panic("getblk: size(%d) > MAXBSIZE(%d)", size, MAXBSIZE);
2193 * Block if we are low on buffers. Certain processes are allowed
2194 * to completely exhaust the buffer cache.
2196 * If this check ever becomes a bottleneck it may be better to
2197 * move it into the else, when gbincore() fails. At the moment
2198 * it isn't a problem.
2200 * XXX remove, we cannot afford to block anywhere if holding a vnode
2201 * lock in low-memory situation, so take it to the max.
2203 if (numfreebuffers == 0) {
2206 needsbuffer |= VFS_BIO_NEED_ANY;
2207 tsleep(&needsbuffer, slpflag, "newbuf", slptimeo);
2210 if ((bp = gbincore(vp, blkno))) {
2212 * Buffer is in-core. If the buffer is not busy, it must
2216 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT)) {
2217 if (BUF_TIMELOCK(bp, LK_EXCLUSIVE | LK_SLEEPFAIL,
2218 "getblk", slpflag, slptimeo) == ENOLCK)
2221 return (struct buf *) NULL;
2225 * The buffer is locked. B_CACHE is cleared if the buffer is
2226 * invalid. Ohterwise, for a non-VMIO buffer, B_CACHE is set
2227 * and for a VMIO buffer B_CACHE is adjusted according to the
2230 if (bp->b_flags & B_INVAL)
2231 bp->b_flags &= ~B_CACHE;
2232 else if ((bp->b_flags & (B_VMIO | B_INVAL)) == 0)
2233 bp->b_flags |= B_CACHE;
2237 * check for size inconsistancies for non-VMIO case.
2240 if (bp->b_bcount != size) {
2241 if ((bp->b_flags & B_VMIO) == 0 ||
2242 (size > bp->b_kvasize)) {
2243 if (bp->b_flags & B_DELWRI) {
2244 bp->b_flags |= B_NOCACHE;
2245 VOP_BWRITE(bp->b_vp, bp);
2247 if ((bp->b_flags & B_VMIO) &&
2248 (LIST_FIRST(&bp->b_dep) == NULL)) {
2249 bp->b_flags |= B_RELBUF;
2252 bp->b_flags |= B_NOCACHE;
2253 VOP_BWRITE(bp->b_vp, bp);
2261 * If the size is inconsistant in the VMIO case, we can resize
2262 * the buffer. This might lead to B_CACHE getting set or
2263 * cleared. If the size has not changed, B_CACHE remains
2264 * unchanged from its previous state.
2267 if (bp->b_bcount != size)
2270 KASSERT(bp->b_offset != NOOFFSET,
2271 ("getblk: no buffer offset"));
2274 * A buffer with B_DELWRI set and B_CACHE clear must
2275 * be committed before we can return the buffer in
2276 * order to prevent the caller from issuing a read
2277 * ( due to B_CACHE not being set ) and overwriting
2280 * Most callers, including NFS and FFS, need this to
2281 * operate properly either because they assume they
2282 * can issue a read if B_CACHE is not set, or because
2283 * ( for example ) an uncached B_DELWRI might loop due
2284 * to softupdates re-dirtying the buffer. In the latter
2285 * case, B_CACHE is set after the first write completes,
2286 * preventing further loops.
2288 * NOTE! b*write() sets B_CACHE. If we cleared B_CACHE
2289 * above while extending the buffer, we cannot allow the
2290 * buffer to remain with B_CACHE set after the write
2291 * completes or it will represent a corrupt state. To
2292 * deal with this we set B_NOCACHE to scrap the buffer
2295 * We might be able to do something fancy, like setting
2296 * B_CACHE in bwrite() except if B_DELWRI is already set,
2297 * so the below call doesn't set B_CACHE, but that gets real
2298 * confusing. This is much easier.
2301 if ((bp->b_flags & (B_CACHE|B_DELWRI)) == B_DELWRI) {
2302 bp->b_flags |= B_NOCACHE;
2303 VOP_BWRITE(bp->b_vp, bp);
2308 bp->b_flags &= ~B_DONE;
2311 * Buffer is not in-core, create new buffer. The buffer
2312 * returned by getnewbuf() is locked. Note that the returned
2313 * buffer is also considered valid (not marked B_INVAL).
2315 * Calculating the offset for the I/O requires figuring out
2316 * the block size. We use DEV_BSIZE for VBLK or VCHR and
2317 * the mount's f_iosize otherwise. If the vnode does not
2318 * have an associated mount we assume that the passed size is
2321 * Note that vn_isdisk() cannot be used here since it may
2322 * return a failure for numerous reasons. Note that the
2323 * buffer size may be larger then the block size (the caller
2324 * will use block numbers with the proper multiple). Beware
2325 * of using any v_* fields which are part of unions. In
2326 * particular, in DragonFly the mount point overloading
2327 * mechanism is such that the underlying directory (with a
2328 * non-NULL v_mountedhere) is not a special case.
2330 int bsize, maxsize, vmio;
2333 if (vp->v_type == VBLK || vp->v_type == VCHR)
2335 else if (vp->v_mount)
2336 bsize = vp->v_mount->mnt_stat.f_iosize;
2340 offset = (off_t)blkno * bsize;
2341 vmio = (VOP_GETVOBJECT(vp, NULL) == 0) && (vp->v_flag & VOBJBUF);
2342 maxsize = vmio ? size + (offset & PAGE_MASK) : size;
2343 maxsize = imax(maxsize, bsize);
2345 if ((bp = getnewbuf(slpflag, slptimeo, size, maxsize)) == NULL) {
2346 if (slpflag || slptimeo) {
2354 * This code is used to make sure that a buffer is not
2355 * created while the getnewbuf routine is blocked.
2356 * This can be a problem whether the vnode is locked or not.
2357 * If the buffer is created out from under us, we have to
2358 * throw away the one we just created. There is now window
2359 * race because we are safely running at splbio() from the
2360 * point of the duplicate buffer creation through to here,
2361 * and we've locked the buffer.
2363 if (gbincore(vp, blkno)) {
2364 bp->b_flags |= B_INVAL;
2370 * Insert the buffer into the hash, so that it can
2371 * be found by incore.
2373 bp->b_blkno = bp->b_lblkno = blkno;
2374 bp->b_offset = offset;
2377 LIST_REMOVE(bp, b_hash);
2378 bh = bufhash(vp, blkno);
2379 LIST_INSERT_HEAD(bh, bp, b_hash);
2382 * set B_VMIO bit. allocbuf() the buffer bigger. Since the
2383 * buffer size starts out as 0, B_CACHE will be set by
2384 * allocbuf() for the VMIO case prior to it testing the
2385 * backing store for validity.
2389 bp->b_flags |= B_VMIO;
2390 #if defined(VFS_BIO_DEBUG)
2391 if (vn_canvmio(vp) != TRUE)
2392 printf("getblk: vmioing file type %d???\n", vp->v_type);
2395 bp->b_flags &= ~B_VMIO;
2401 bp->b_flags &= ~B_DONE;
2407 * Get an empty, disassociated buffer of given size. The buffer is initially
2410 * spl protection is not required for the allocbuf() call because races are
2420 maxsize = (size + BKVAMASK) & ~BKVAMASK;
2423 while ((bp = getnewbuf(0, 0, size, maxsize)) == 0);
2426 bp->b_flags |= B_INVAL; /* b_dep cleared by getnewbuf() */
2432 * This code constitutes the buffer memory from either anonymous system
2433 * memory (in the case of non-VMIO operations) or from an associated
2434 * VM object (in the case of VMIO operations). This code is able to
2435 * resize a buffer up or down.
2437 * Note that this code is tricky, and has many complications to resolve
2438 * deadlock or inconsistant data situations. Tread lightly!!!
2439 * There are B_CACHE and B_DELWRI interactions that must be dealt with by
2440 * the caller. Calling this code willy nilly can result in the loss of data.
2442 * allocbuf() only adjusts B_CACHE for VMIO buffers. getblk() deals with
2443 * B_CACHE for the non-VMIO case.
2445 * This routine does not need to be called at splbio() but you must own the
2449 allocbuf(struct buf *bp, int size)
2451 int newbsize, mbsize;
2454 if (BUF_REFCNT(bp) == 0)
2455 panic("allocbuf: buffer not busy");
2457 if (bp->b_kvasize < size)
2458 panic("allocbuf: buffer too small");
2460 if ((bp->b_flags & B_VMIO) == 0) {
2464 * Just get anonymous memory from the kernel. Don't
2465 * mess with B_CACHE.
2467 mbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1);
2468 #if !defined(NO_B_MALLOC)
2469 if (bp->b_flags & B_MALLOC)
2473 newbsize = round_page(size);
2475 if (newbsize < bp->b_bufsize) {
2476 #if !defined(NO_B_MALLOC)
2478 * malloced buffers are not shrunk
2480 if (bp->b_flags & B_MALLOC) {
2482 bp->b_bcount = size;
2484 free(bp->b_data, M_BIOBUF);
2485 if (bp->b_bufsize) {
2486 bufmallocspace -= bp->b_bufsize;
2490 bp->b_data = bp->b_kvabase;
2492 bp->b_flags &= ~B_MALLOC;
2499 (vm_offset_t) bp->b_data + newbsize,
2500 (vm_offset_t) bp->b_data + bp->b_bufsize);
2501 } else if (newbsize > bp->b_bufsize) {
2502 #if !defined(NO_B_MALLOC)
2504 * We only use malloced memory on the first allocation.
2505 * and revert to page-allocated memory when the buffer
2508 if ( (bufmallocspace < maxbufmallocspace) &&
2509 (bp->b_bufsize == 0) &&
2510 (mbsize <= PAGE_SIZE/2)) {
2512 bp->b_data = malloc(mbsize, M_BIOBUF, M_WAITOK);
2513 bp->b_bufsize = mbsize;
2514 bp->b_bcount = size;
2515 bp->b_flags |= B_MALLOC;
2516 bufmallocspace += mbsize;
2522 #if !defined(NO_B_MALLOC)
2524 * If the buffer is growing on its other-than-first allocation,
2525 * then we revert to the page-allocation scheme.
2527 if (bp->b_flags & B_MALLOC) {
2528 origbuf = bp->b_data;
2529 origbufsize = bp->b_bufsize;
2530 bp->b_data = bp->b_kvabase;
2531 if (bp->b_bufsize) {
2532 bufmallocspace -= bp->b_bufsize;
2536 bp->b_flags &= ~B_MALLOC;
2537 newbsize = round_page(newbsize);
2542 (vm_offset_t) bp->b_data + bp->b_bufsize,
2543 (vm_offset_t) bp->b_data + newbsize);
2544 #if !defined(NO_B_MALLOC)
2546 bcopy(origbuf, bp->b_data, origbufsize);
2547 free(origbuf, M_BIOBUF);
2555 newbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1);
2556 desiredpages = (size == 0) ? 0 :
2557 num_pages((bp->b_offset & PAGE_MASK) + newbsize);
2559 #if !defined(NO_B_MALLOC)
2560 if (bp->b_flags & B_MALLOC)
2561 panic("allocbuf: VMIO buffer can't be malloced");
2564 * Set B_CACHE initially if buffer is 0 length or will become
2567 if (size == 0 || bp->b_bufsize == 0)
2568 bp->b_flags |= B_CACHE;
2570 if (newbsize < bp->b_bufsize) {
2572 * DEV_BSIZE aligned new buffer size is less then the
2573 * DEV_BSIZE aligned existing buffer size. Figure out
2574 * if we have to remove any pages.
2576 if (desiredpages < bp->b_xio.xio_npages) {
2577 for (i = desiredpages; i < bp->b_xio.xio_npages; i++) {
2579 * the page is not freed here -- it
2580 * is the responsibility of
2581 * vnode_pager_setsize
2583 m = bp->b_xio.xio_pages[i];
2584 KASSERT(m != bogus_page,
2585 ("allocbuf: bogus page found"));
2586 while (vm_page_sleep_busy(m, TRUE, "biodep"))
2589 bp->b_xio.xio_pages[i] = NULL;
2590 vm_page_unwire(m, 0);
2592 pmap_qremove((vm_offset_t) trunc_page((vm_offset_t)bp->b_data) +
2593 (desiredpages << PAGE_SHIFT), (bp->b_xio.xio_npages - desiredpages));
2594 bp->b_xio.xio_npages = desiredpages;
2596 } else if (size > bp->b_bcount) {
2598 * We are growing the buffer, possibly in a
2599 * byte-granular fashion.
2607 * Step 1, bring in the VM pages from the object,
2608 * allocating them if necessary. We must clear
2609 * B_CACHE if these pages are not valid for the
2610 * range covered by the buffer.
2612 * spl protection is required to protect against
2613 * interrupts unbusying and freeing pages between
2614 * our vm_page_lookup() and our busycheck/wiring
2618 VOP_GETVOBJECT(vp, &obj);
2621 while (bp->b_xio.xio_npages < desiredpages) {
2625 pi = OFF_TO_IDX(bp->b_offset) + bp->b_xio.xio_npages;
2626 if ((m = vm_page_lookup(obj, pi)) == NULL) {
2628 * note: must allocate system pages
2629 * since blocking here could intefere
2630 * with paging I/O, no matter which
2633 m = vm_page_alloc(obj, pi, VM_ALLOC_NORMAL | VM_ALLOC_SYSTEM);
2636 vm_pageout_deficit += desiredpages -
2637 bp->b_xio.xio_npages;
2641 bp->b_flags &= ~B_CACHE;
2642 bp->b_xio.xio_pages[bp->b_xio.xio_npages] = m;
2643 ++bp->b_xio.xio_npages;
2649 * We found a page. If we have to sleep on it,
2650 * retry because it might have gotten freed out
2653 * We can only test PG_BUSY here. Blocking on
2654 * m->busy might lead to a deadlock:
2656 * vm_fault->getpages->cluster_read->allocbuf
2660 if (vm_page_sleep_busy(m, FALSE, "pgtblk"))
2664 * We have a good page. Should we wakeup the
2667 if ((curthread != pagethread) &&
2668 ((m->queue - m->pc) == PQ_CACHE) &&
2669 ((vmstats.v_free_count + vmstats.v_cache_count) <
2670 (vmstats.v_free_min + vmstats.v_cache_min))) {
2671 pagedaemon_wakeup();
2673 vm_page_flag_clear(m, PG_ZERO);
2675 bp->b_xio.xio_pages[bp->b_xio.xio_npages] = m;
2676 ++bp->b_xio.xio_npages;
2681 * Step 2. We've loaded the pages into the buffer,
2682 * we have to figure out if we can still have B_CACHE
2683 * set. Note that B_CACHE is set according to the
2684 * byte-granular range ( bcount and size ), new the
2685 * aligned range ( newbsize ).
2687 * The VM test is against m->valid, which is DEV_BSIZE
2688 * aligned. Needless to say, the validity of the data
2689 * needs to also be DEV_BSIZE aligned. Note that this
2690 * fails with NFS if the server or some other client
2691 * extends the file's EOF. If our buffer is resized,
2692 * B_CACHE may remain set! XXX
2695 toff = bp->b_bcount;
2696 tinc = PAGE_SIZE - ((bp->b_offset + toff) & PAGE_MASK);
2698 while ((bp->b_flags & B_CACHE) && toff < size) {
2701 if (tinc > (size - toff))
2704 pi = ((bp->b_offset & PAGE_MASK) + toff) >>
2712 bp->b_xio.xio_pages[pi]
2719 * Step 3, fixup the KVM pmap. Remember that
2720 * bp->b_data is relative to bp->b_offset, but
2721 * bp->b_offset may be offset into the first page.
2724 bp->b_data = (caddr_t)
2725 trunc_page((vm_offset_t)bp->b_data);
2727 (vm_offset_t)bp->b_data,
2728 bp->b_xio.xio_pages,
2729 bp->b_xio.xio_npages
2731 bp->b_data = (caddr_t)((vm_offset_t)bp->b_data |
2732 (vm_offset_t)(bp->b_offset & PAGE_MASK));
2735 if (newbsize < bp->b_bufsize)
2737 bp->b_bufsize = newbsize; /* actual buffer allocation */
2738 bp->b_bcount = size; /* requested buffer size */
2745 * Wait for buffer I/O completion, returning error status. The buffer
2746 * is left locked and B_DONE on return. B_EINTR is converted into a EINTR
2747 * error and cleared.
2750 biowait(struct buf * bp)
2755 while ((bp->b_flags & B_DONE) == 0) {
2756 #if defined(NO_SCHEDULE_MODS)
2757 tsleep(bp, 0, "biowait", 0);
2759 if (bp->b_flags & B_READ)
2760 tsleep(bp, 0, "biord", 0);
2762 tsleep(bp, 0, "biowr", 0);
2766 if (bp->b_flags & B_EINTR) {
2767 bp->b_flags &= ~B_EINTR;
2770 if (bp->b_flags & B_ERROR) {
2771 return (bp->b_error ? bp->b_error : EIO);
2780 * Finish I/O on a buffer, optionally calling a completion function.
2781 * This is usually called from an interrupt so process blocking is
2784 * biodone is also responsible for setting B_CACHE in a B_VMIO bp.
2785 * In a non-VMIO bp, B_CACHE will be set on the next getblk()
2786 * assuming B_INVAL is clear.
2788 * For the VMIO case, we set B_CACHE if the op was a read and no
2789 * read error occured, or if the op was a write. B_CACHE is never
2790 * set if the buffer is invalid or otherwise uncacheable.
2792 * biodone does not mess with B_INVAL, allowing the I/O routine or the
2793 * initiator to leave B_INVAL set to brelse the buffer out of existance
2794 * in the biodone routine.
2796 * b_dev is required to be reinitialized prior to the top level strategy
2797 * call in a device stack. To avoid improper reuse, biodone() sets
2801 biodone(struct buf *bp)
2807 KASSERT(BUF_REFCNTNB(bp) > 0, ("biodone: bp %p not busy %d", bp, BUF_REFCNTNB(bp)));
2808 KASSERT(!(bp->b_flags & B_DONE), ("biodone: bp %p already done", bp));
2810 bp->b_flags |= B_DONE;
2812 runningbufwakeup(bp);
2814 if (bp->b_flags & B_FREEBUF) {
2820 if ((bp->b_flags & B_READ) == 0) {
2824 /* call optional completion function if requested */
2825 if (bp->b_flags & B_CALL) {
2826 bp->b_flags &= ~B_CALL;
2827 (*bp->b_iodone) (bp);
2831 if (LIST_FIRST(&bp->b_dep) != NULL && bioops.io_complete)
2832 (*bioops.io_complete)(bp);
2834 if (bp->b_flags & B_VMIO) {
2840 struct vnode *vp = bp->b_vp;
2842 error = VOP_GETVOBJECT(vp, &obj);
2844 #if defined(VFS_BIO_DEBUG)
2845 if (vp->v_holdcnt == 0) {
2846 panic("biodone: zero vnode hold count");
2850 panic("biodone: missing VM object");
2853 if ((vp->v_flag & VOBJBUF) == 0) {
2854 panic("biodone: vnode is not setup for merged cache");
2858 foff = bp->b_offset;
2859 KASSERT(bp->b_offset != NOOFFSET,
2860 ("biodone: no buffer offset"));
2863 panic("biodone: no object");
2865 #if defined(VFS_BIO_DEBUG)
2866 if (obj->paging_in_progress < bp->b_xio.xio_npages) {
2867 printf("biodone: paging in progress(%d) < bp->b_xio.xio_npages(%d)\n",
2868 obj->paging_in_progress, bp->b_xio.xio_npages);
2873 * Set B_CACHE if the op was a normal read and no error
2874 * occured. B_CACHE is set for writes in the b*write()
2877 iosize = bp->b_bcount - bp->b_resid;
2878 if ((bp->b_flags & (B_READ|B_FREEBUF|B_INVAL|B_NOCACHE|B_ERROR)) == B_READ) {
2879 bp->b_flags |= B_CACHE;
2882 for (i = 0; i < bp->b_xio.xio_npages; i++) {
2886 resid = ((foff + PAGE_SIZE) & ~(off_t)PAGE_MASK) - foff;
2891 * cleanup bogus pages, restoring the originals. Since
2892 * the originals should still be wired, we don't have
2893 * to worry about interrupt/freeing races destroying
2894 * the VM object association.
2896 m = bp->b_xio.xio_pages[i];
2897 if (m == bogus_page) {
2899 m = vm_page_lookup(obj, OFF_TO_IDX(foff));
2901 panic("biodone: page disappeared");
2902 bp->b_xio.xio_pages[i] = m;
2903 pmap_qenter(trunc_page((vm_offset_t)bp->b_data),
2904 bp->b_xio.xio_pages, bp->b_xio.xio_npages);
2906 #if defined(VFS_BIO_DEBUG)
2907 if (OFF_TO_IDX(foff) != m->pindex) {
2909 "biodone: foff(%lu)/m->pindex(%d) mismatch\n",
2910 (unsigned long)foff, m->pindex);
2915 * In the write case, the valid and clean bits are
2916 * already changed correctly ( see bdwrite() ), so we
2917 * only need to do this here in the read case.
2919 if ((bp->b_flags & B_READ) && !bogusflag && resid > 0) {
2920 vfs_page_set_valid(bp, foff, i, m);
2922 vm_page_flag_clear(m, PG_ZERO);
2925 * when debugging new filesystems or buffer I/O methods, this
2926 * is the most common error that pops up. if you see this, you
2927 * have not set the page busy flag correctly!!!
2930 printf("biodone: page busy < 0, "
2931 "pindex: %d, foff: 0x(%x,%x), "
2932 "resid: %d, index: %d\n",
2933 (int) m->pindex, (int)(foff >> 32),
2934 (int) foff & 0xffffffff, resid, i);
2935 if (!vn_isdisk(vp, NULL))
2936 printf(" iosize: %ld, lblkno: %d, flags: 0x%lx, npages: %d\n",
2937 bp->b_vp->v_mount->mnt_stat.f_iosize,
2939 bp->b_flags, bp->b_xio.xio_npages);
2941 printf(" VDEV, lblkno: %d, flags: 0x%lx, npages: %d\n",
2943 bp->b_flags, bp->b_xio.xio_npages);
2944 printf(" valid: 0x%x, dirty: 0x%x, wired: %d\n",
2945 m->valid, m->dirty, m->wire_count);
2946 panic("biodone: page busy < 0");
2948 vm_page_io_finish(m);
2949 vm_object_pip_subtract(obj, 1);
2950 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK;
2954 vm_object_pip_wakeupn(obj, 0);
2958 * For asynchronous completions, release the buffer now. The brelse
2959 * will do a wakeup there if necessary - so no need to do a wakeup
2960 * here in the async case. The sync case always needs to do a wakeup.
2963 if (bp->b_flags & B_ASYNC) {
2964 if ((bp->b_flags & (B_NOCACHE | B_INVAL | B_ERROR | B_RELBUF)) != 0)
2975 * This routine is called in lieu of iodone in the case of
2976 * incomplete I/O. This keeps the busy status for pages
2980 vfs_unbusy_pages(struct buf *bp)
2984 runningbufwakeup(bp);
2985 if (bp->b_flags & B_VMIO) {
2986 struct vnode *vp = bp->b_vp;
2989 VOP_GETVOBJECT(vp, &obj);
2991 for (i = 0; i < bp->b_xio.xio_npages; i++) {
2992 vm_page_t m = bp->b_xio.xio_pages[i];
2995 * When restoring bogus changes the original pages
2996 * should still be wired, so we are in no danger of
2997 * losing the object association and do not need
2998 * spl protection particularly.
3000 if (m == bogus_page) {
3001 m = vm_page_lookup(obj, OFF_TO_IDX(bp->b_offset) + i);
3003 panic("vfs_unbusy_pages: page missing");
3005 bp->b_xio.xio_pages[i] = m;
3006 pmap_qenter(trunc_page((vm_offset_t)bp->b_data),
3007 bp->b_xio.xio_pages, bp->b_xio.xio_npages);
3009 vm_object_pip_subtract(obj, 1);
3010 vm_page_flag_clear(m, PG_ZERO);
3011 vm_page_io_finish(m);
3013 vm_object_pip_wakeupn(obj, 0);
3018 * vfs_page_set_valid:
3020 * Set the valid bits in a page based on the supplied offset. The
3021 * range is restricted to the buffer's size.
3023 * This routine is typically called after a read completes.
3026 vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, int pageno, vm_page_t m)
3028 vm_ooffset_t soff, eoff;
3031 * Start and end offsets in buffer. eoff - soff may not cross a
3032 * page boundry or cross the end of the buffer. The end of the
3033 * buffer, in this case, is our file EOF, not the allocation size
3037 eoff = (off + PAGE_SIZE) & ~(off_t)PAGE_MASK;
3038 if (eoff > bp->b_offset + bp->b_bcount)
3039 eoff = bp->b_offset + bp->b_bcount;
3042 * Set valid range. This is typically the entire buffer and thus the
3046 vm_page_set_validclean(
3048 (vm_offset_t) (soff & PAGE_MASK),
3049 (vm_offset_t) (eoff - soff)
3055 * This routine is called before a device strategy routine.
3056 * It is used to tell the VM system that paging I/O is in
3057 * progress, and treat the pages associated with the buffer
3058 * almost as being PG_BUSY. Also the object paging_in_progress
3059 * flag is handled to make sure that the object doesn't become
3062 * Since I/O has not been initiated yet, certain buffer flags
3063 * such as B_ERROR or B_INVAL may be in an inconsistant state
3064 * and should be ignored.
3067 vfs_busy_pages(struct buf *bp, int clear_modify)
3071 if (bp->b_flags & B_VMIO) {
3072 struct vnode *vp = bp->b_vp;
3076 VOP_GETVOBJECT(vp, &obj);
3077 foff = bp->b_offset;
3078 KASSERT(bp->b_offset != NOOFFSET,
3079 ("vfs_busy_pages: no buffer offset"));
3083 for (i = 0; i < bp->b_xio.xio_npages; i++) {
3084 vm_page_t m = bp->b_xio.xio_pages[i];
3085 if (vm_page_sleep_busy(m, FALSE, "vbpage"))
3090 for (i = 0; i < bp->b_xio.xio_npages; i++) {
3091 vm_page_t m = bp->b_xio.xio_pages[i];
3093 vm_page_flag_clear(m, PG_ZERO);
3094 if ((bp->b_flags & B_CLUSTER) == 0) {
3095 vm_object_pip_add(obj, 1);
3096 vm_page_io_start(m);
3100 * When readying a buffer for a read ( i.e
3101 * clear_modify == 0 ), it is important to do
3102 * bogus_page replacement for valid pages in
3103 * partially instantiated buffers. Partially
3104 * instantiated buffers can, in turn, occur when
3105 * reconstituting a buffer from its VM backing store
3106 * base. We only have to do this if B_CACHE is
3107 * clear ( which causes the I/O to occur in the
3108 * first place ). The replacement prevents the read
3109 * I/O from overwriting potentially dirty VM-backed
3110 * pages. XXX bogus page replacement is, uh, bogus.
3111 * It may not work properly with small-block devices.
3112 * We need to find a better way.
3115 vm_page_protect(m, VM_PROT_NONE);
3117 vfs_page_set_valid(bp, foff, i, m);
3118 else if (m->valid == VM_PAGE_BITS_ALL &&
3119 (bp->b_flags & B_CACHE) == 0) {
3120 bp->b_xio.xio_pages[i] = bogus_page;
3123 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK;
3126 pmap_qenter(trunc_page((vm_offset_t)bp->b_data),
3127 bp->b_xio.xio_pages, bp->b_xio.xio_npages);
3131 * This is the easiest place to put the process accounting for the I/O
3137 if ((p = curthread->td_proc) != NULL) {
3138 if (bp->b_flags & B_READ)
3139 p->p_stats->p_ru.ru_inblock++;
3141 p->p_stats->p_ru.ru_oublock++;
3147 * Tell the VM system that the pages associated with this buffer
3148 * are clean. This is used for delayed writes where the data is
3149 * going to go to disk eventually without additional VM intevention.
3151 * Note that while we only really need to clean through to b_bcount, we
3152 * just go ahead and clean through to b_bufsize.
3155 vfs_clean_pages(struct buf *bp)
3159 if (bp->b_flags & B_VMIO) {
3162 foff = bp->b_offset;
3163 KASSERT(bp->b_offset != NOOFFSET,
3164 ("vfs_clean_pages: no buffer offset"));
3165 for (i = 0; i < bp->b_xio.xio_npages; i++) {
3166 vm_page_t m = bp->b_xio.xio_pages[i];
3167 vm_ooffset_t noff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK;
3168 vm_ooffset_t eoff = noff;
3170 if (eoff > bp->b_offset + bp->b_bufsize)
3171 eoff = bp->b_offset + bp->b_bufsize;
3172 vfs_page_set_valid(bp, foff, i, m);
3173 /* vm_page_clear_dirty(m, foff & PAGE_MASK, eoff - foff); */
3180 * vfs_bio_set_validclean:
3182 * Set the range within the buffer to valid and clean. The range is
3183 * relative to the beginning of the buffer, b_offset. Note that b_offset
3184 * itself may be offset from the beginning of the first page.
3188 vfs_bio_set_validclean(struct buf *bp, int base, int size)
3190 if (bp->b_flags & B_VMIO) {
3195 * Fixup base to be relative to beginning of first page.
3196 * Set initial n to be the maximum number of bytes in the
3197 * first page that can be validated.
3200 base += (bp->b_offset & PAGE_MASK);
3201 n = PAGE_SIZE - (base & PAGE_MASK);
3203 for (i = base / PAGE_SIZE; size > 0 && i < bp->b_xio.xio_npages; ++i) {
3204 vm_page_t m = bp->b_xio.xio_pages[i];
3209 vm_page_set_validclean(m, base & PAGE_MASK, n);
3220 * clear a buffer. This routine essentially fakes an I/O, so we need
3221 * to clear B_ERROR and B_INVAL.
3223 * Note that while we only theoretically need to clear through b_bcount,
3224 * we go ahead and clear through b_bufsize.
3228 vfs_bio_clrbuf(struct buf *bp)
3232 if ((bp->b_flags & (B_VMIO | B_MALLOC)) == B_VMIO) {
3233 bp->b_flags &= ~(B_INVAL|B_ERROR);
3234 if ((bp->b_xio.xio_npages == 1) && (bp->b_bufsize < PAGE_SIZE) &&
3235 (bp->b_offset & PAGE_MASK) == 0) {
3236 mask = (1 << (bp->b_bufsize / DEV_BSIZE)) - 1;
3237 if ((bp->b_xio.xio_pages[0]->valid & mask) == mask) {
3241 if (((bp->b_xio.xio_pages[0]->flags & PG_ZERO) == 0) &&
3242 ((bp->b_xio.xio_pages[0]->valid & mask) == 0)) {
3243 bzero(bp->b_data, bp->b_bufsize);
3244 bp->b_xio.xio_pages[0]->valid |= mask;
3249 ea = sa = bp->b_data;
3250 for(i=0;i<bp->b_xio.xio_npages;i++,sa=ea) {
3251 int j = ((vm_offset_t)sa & PAGE_MASK) / DEV_BSIZE;
3252 ea = (caddr_t)trunc_page((vm_offset_t)sa + PAGE_SIZE);
3253 ea = (caddr_t)(vm_offset_t)ulmin(
3254 (u_long)(vm_offset_t)ea,
3255 (u_long)(vm_offset_t)bp->b_data + bp->b_bufsize);
3256 mask = ((1 << ((ea - sa) / DEV_BSIZE)) - 1) << j;
3257 if ((bp->b_xio.xio_pages[i]->valid & mask) == mask)
3259 if ((bp->b_xio.xio_pages[i]->valid & mask) == 0) {
3260 if ((bp->b_xio.xio_pages[i]->flags & PG_ZERO) == 0) {
3264 for (; sa < ea; sa += DEV_BSIZE, j++) {
3265 if (((bp->b_xio.xio_pages[i]->flags & PG_ZERO) == 0) &&
3266 (bp->b_xio.xio_pages[i]->valid & (1<<j)) == 0)
3267 bzero(sa, DEV_BSIZE);
3270 bp->b_xio.xio_pages[i]->valid |= mask;
3271 vm_page_flag_clear(bp->b_xio.xio_pages[i], PG_ZERO);
3280 * vm_hold_load_pages and vm_hold_unload pages get pages into
3281 * a buffers address space. The pages are anonymous and are
3282 * not associated with a file object.
3285 vm_hold_load_pages(struct buf *bp, vm_offset_t from, vm_offset_t to)
3291 to = round_page(to);
3292 from = round_page(from);
3293 index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT;
3295 for (pg = from; pg < to; pg += PAGE_SIZE, index++) {
3300 * note: must allocate system pages since blocking here
3301 * could intefere with paging I/O, no matter which
3304 p = vm_page_alloc(kernel_object,
3305 ((pg - VM_MIN_KERNEL_ADDRESS) >> PAGE_SHIFT),
3306 VM_ALLOC_NORMAL | VM_ALLOC_SYSTEM);
3308 vm_pageout_deficit += (to - from) >> PAGE_SHIFT;
3313 p->valid = VM_PAGE_BITS_ALL;
3314 vm_page_flag_clear(p, PG_ZERO);
3315 pmap_kenter(pg, VM_PAGE_TO_PHYS(p));
3316 bp->b_xio.xio_pages[index] = p;
3319 bp->b_xio.xio_npages = index;
3323 vm_hold_free_pages(struct buf *bp, vm_offset_t from, vm_offset_t to)
3327 int index, newnpages;
3329 from = round_page(from);
3330 to = round_page(to);
3331 newnpages = index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT;
3333 for (pg = from; pg < to; pg += PAGE_SIZE, index++) {
3334 p = bp->b_xio.xio_pages[index];
3335 if (p && (index < bp->b_xio.xio_npages)) {
3337 printf("vm_hold_free_pages: blkno: %d, lblkno: %d\n",
3338 bp->b_blkno, bp->b_lblkno);
3340 bp->b_xio.xio_pages[index] = NULL;
3343 vm_page_unwire(p, 0);
3347 bp->b_xio.xio_npages = newnpages;
3351 * Map an IO request into kernel virtual address space.
3353 * All requests are (re)mapped into kernel VA space.
3354 * Notice that we use b_bufsize for the size of the buffer
3355 * to be mapped. b_bcount might be modified by the driver.
3358 vmapbuf(struct buf *bp)
3360 caddr_t addr, v, kva;
3366 if ((bp->b_flags & B_PHYS) == 0)
3368 if (bp->b_bufsize < 0)
3370 for (v = bp->b_saveaddr,
3371 addr = (caddr_t)trunc_page((vm_offset_t)bp->b_data),
3373 addr < bp->b_data + bp->b_bufsize;
3374 addr += PAGE_SIZE, v += PAGE_SIZE, pidx++) {
3376 * Do the vm_fault if needed; do the copy-on-write thing
3377 * when reading stuff off device into memory.
3380 i = vm_fault_quick((addr >= bp->b_data) ? addr : bp->b_data,
3381 (bp->b_flags&B_READ)?(VM_PROT_READ|VM_PROT_WRITE):VM_PROT_READ);
3383 for (i = 0; i < pidx; ++i) {
3384 vm_page_unhold(bp->b_xio.xio_pages[i]);
3385 bp->b_xio.xio_pages[i] = NULL;
3391 * WARNING! If sparc support is MFCd in the future this will
3392 * have to be changed from pmap_kextract() to pmap_extract()
3396 #error "If MFCing sparc support use pmap_extract"
3398 pa = pmap_kextract((vm_offset_t)addr);
3400 printf("vmapbuf: warning, race against user address during I/O");
3403 m = PHYS_TO_VM_PAGE(pa);
3405 bp->b_xio.xio_pages[pidx] = m;
3407 if (pidx > btoc(MAXPHYS))
3408 panic("vmapbuf: mapped more than MAXPHYS");
3409 pmap_qenter((vm_offset_t)bp->b_saveaddr, bp->b_xio.xio_pages, pidx);
3411 kva = bp->b_saveaddr;
3412 bp->b_xio.xio_npages = pidx;
3413 bp->b_saveaddr = bp->b_data;
3414 bp->b_data = kva + (((vm_offset_t) bp->b_data) & PAGE_MASK);
3419 * Free the io map PTEs associated with this IO operation.
3420 * We also invalidate the TLB entries and restore the original b_addr.
3423 vunmapbuf(struct buf *bp)
3429 if ((bp->b_flags & B_PHYS) == 0)
3432 npages = bp->b_xio.xio_npages;
3433 pmap_qremove(trunc_page((vm_offset_t)bp->b_data),
3435 m = bp->b_xio.xio_pages;
3436 for (pidx = 0; pidx < npages; pidx++)
3437 vm_page_unhold(*m++);
3439 bp->b_data = bp->b_saveaddr;
3442 #include "opt_ddb.h"
3444 #include <ddb/ddb.h>
3446 DB_SHOW_COMMAND(buffer, db_show_buffer)
3449 struct buf *bp = (struct buf *)addr;
3452 db_printf("usage: show buffer <addr>\n");
3456 db_printf("b_flags = 0x%b\n", (u_int)bp->b_flags, PRINT_BUF_FLAGS);
3457 db_printf("b_error = %d, b_bufsize = %ld, b_bcount = %ld, "
3458 "b_resid = %ld\nb_dev = (%d,%d), b_data = %p, "
3459 "b_blkno = %d, b_pblkno = %d\n",
3460 bp->b_error, bp->b_bufsize, bp->b_bcount, bp->b_resid,
3461 major(bp->b_dev), minor(bp->b_dev),
3462 bp->b_data, bp->b_blkno, bp->b_pblkno);
3463 if (bp->b_xio.xio_npages) {
3465 db_printf("b_xio.xio_npages = %d, pages(OBJ, IDX, PA): ",
3466 bp->b_xio.xio_npages);
3467 for (i = 0; i < bp->b_xio.xio_npages; i++) {
3469 m = bp->b_xio.xio_pages[i];
3470 db_printf("(%p, 0x%lx, 0x%lx)", (void *)m->object,
3471 (u_long)m->pindex, (u_long)VM_PAGE_TO_PHYS(m));
3472 if ((i + 1) < bp->b_xio.xio_npages)