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 1.32 2004/11/09 17:36:41 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);
77 static void vfs_backgroundwritedone(struct buf *bp);
78 static int flushbufqueues(void);
80 static int bd_request;
82 static void buf_daemon (void);
84 * bogus page -- for I/O to/from partially complete buffers
85 * this is a temporary solution to the problem, but it is not
86 * really that bad. it would be better to split the buffer
87 * for input in the case of buffers partially already in memory,
88 * but the code is intricate enough already.
91 int vmiodirenable = TRUE;
93 struct lwkt_token buftimetoken; /* Interlock on setting prio and timo */
95 static vm_offset_t bogus_offset;
97 static int bufspace, maxbufspace,
98 bufmallocspace, maxbufmallocspace, lobufspace, hibufspace;
99 static int bufreusecnt, bufdefragcnt, buffreekvacnt;
100 static int needsbuffer;
101 static int lorunningspace, hirunningspace, runningbufreq;
102 static int numdirtybuffers, lodirtybuffers, hidirtybuffers;
103 static int numfreebuffers, lofreebuffers, hifreebuffers;
104 static int getnewbufcalls;
105 static int getnewbufrestarts;
107 SYSCTL_INT(_vfs, OID_AUTO, numdirtybuffers, CTLFLAG_RD,
108 &numdirtybuffers, 0, "");
109 SYSCTL_INT(_vfs, OID_AUTO, lodirtybuffers, CTLFLAG_RW,
110 &lodirtybuffers, 0, "");
111 SYSCTL_INT(_vfs, OID_AUTO, hidirtybuffers, CTLFLAG_RW,
112 &hidirtybuffers, 0, "");
113 SYSCTL_INT(_vfs, OID_AUTO, numfreebuffers, CTLFLAG_RD,
114 &numfreebuffers, 0, "");
115 SYSCTL_INT(_vfs, OID_AUTO, lofreebuffers, CTLFLAG_RW,
116 &lofreebuffers, 0, "");
117 SYSCTL_INT(_vfs, OID_AUTO, hifreebuffers, CTLFLAG_RW,
118 &hifreebuffers, 0, "");
119 SYSCTL_INT(_vfs, OID_AUTO, runningbufspace, CTLFLAG_RD,
120 &runningbufspace, 0, "");
121 SYSCTL_INT(_vfs, OID_AUTO, lorunningspace, CTLFLAG_RW,
122 &lorunningspace, 0, "");
123 SYSCTL_INT(_vfs, OID_AUTO, hirunningspace, CTLFLAG_RW,
124 &hirunningspace, 0, "");
125 SYSCTL_INT(_vfs, OID_AUTO, maxbufspace, CTLFLAG_RD,
126 &maxbufspace, 0, "");
127 SYSCTL_INT(_vfs, OID_AUTO, hibufspace, CTLFLAG_RD,
129 SYSCTL_INT(_vfs, OID_AUTO, lobufspace, CTLFLAG_RD,
131 SYSCTL_INT(_vfs, OID_AUTO, bufspace, CTLFLAG_RD,
133 SYSCTL_INT(_vfs, OID_AUTO, maxmallocbufspace, CTLFLAG_RW,
134 &maxbufmallocspace, 0, "");
135 SYSCTL_INT(_vfs, OID_AUTO, bufmallocspace, CTLFLAG_RD,
136 &bufmallocspace, 0, "");
137 SYSCTL_INT(_vfs, OID_AUTO, getnewbufcalls, CTLFLAG_RW,
138 &getnewbufcalls, 0, "");
139 SYSCTL_INT(_vfs, OID_AUTO, getnewbufrestarts, CTLFLAG_RW,
140 &getnewbufrestarts, 0, "");
141 SYSCTL_INT(_vfs, OID_AUTO, vmiodirenable, CTLFLAG_RW,
142 &vmiodirenable, 0, "");
143 SYSCTL_INT(_vfs, OID_AUTO, bufdefragcnt, CTLFLAG_RW,
144 &bufdefragcnt, 0, "");
145 SYSCTL_INT(_vfs, OID_AUTO, buffreekvacnt, CTLFLAG_RW,
146 &buffreekvacnt, 0, "");
147 SYSCTL_INT(_vfs, OID_AUTO, bufreusecnt, CTLFLAG_RW,
148 &bufreusecnt, 0, "");
151 * Disable background writes for now. There appear to be races in the
152 * flags tests and locking operations as well as races in the completion
153 * code modifying the original bp (origbp) without holding a lock, assuming
154 * splbio protection when there might not be splbio protection.
156 static int dobkgrdwrite = 0;
157 SYSCTL_INT(_debug, OID_AUTO, dobkgrdwrite, CTLFLAG_RW, &dobkgrdwrite, 0,
158 "Do background writes (honoring the BV_BKGRDWRITE flag)?");
160 static int bufhashmask;
161 static int bufhashshift;
162 static LIST_HEAD(bufhashhdr, buf) *bufhashtbl, invalhash;
163 struct bqueues bufqueues[BUFFER_QUEUES] = { { 0 } };
164 char *buf_wmesg = BUF_WMESG;
166 extern int vm_swap_size;
168 #define VFS_BIO_NEED_ANY 0x01 /* any freeable buffer */
169 #define VFS_BIO_NEED_DIRTYFLUSH 0x02 /* waiting for dirty buffer flush */
170 #define VFS_BIO_NEED_FREE 0x04 /* wait for free bufs, hi hysteresis */
171 #define VFS_BIO_NEED_BUFSPACE 0x08 /* wait for buf space, lo hysteresis */
174 * Buffer hash table code. Note that the logical block scans linearly, which
175 * gives us some L1 cache locality.
180 bufhash(struct vnode *vnp, daddr_t bn)
186 * A variation on the Fibonacci hash that Knuth credits to
187 * R. W. Floyd, see Knuth's _Art of Computer Programming,
188 * Volume 3 / Sorting and Searching_
190 * We reduce the argument to 32 bits before doing the hash to
191 * avoid the need for a slow 64x64 multiply on 32 bit platforms.
193 * sizeof(struct vnode) is 168 on i386, so toss some of the lower
194 * bits of the vnode address to reduce the key range, which
195 * improves the distribution of keys across buckets.
197 * The file system cylinder group blocks are very heavily
198 * used. They are located at invervals of fbg, which is
199 * on the order of 89 to 94 * 2^10, depending on other
200 * filesystem parameters, for a 16k block size. Smaller block
201 * sizes will reduce fpg approximately proportionally. This
202 * will cause the cylinder group index to be hashed using the
203 * lower bits of the hash multiplier, which will not distribute
204 * the keys as uniformly in a classic Fibonacci hash where a
205 * relatively small number of the upper bits of the result
206 * are used. Using 2^16 as a close-enough approximation to
207 * fpg, split the hash multiplier in half, with the upper 16
208 * bits being the inverse of the golden ratio, and the lower
209 * 16 bits being a fraction between 1/3 and 3/7 (closer to
210 * 3/7 in this case), that gives good experimental results.
212 hashkey64 = ((u_int64_t)(uintptr_t)vnp >> 3) + (u_int64_t)bn;
213 hashkey = (((u_int32_t)(hashkey64 + (hashkey64 >> 32)) * 0x9E376DB1u) >>
214 bufhashshift) & bufhashmask;
215 return(&bufhashtbl[hashkey]);
221 * If someone is blocked due to there being too many dirty buffers,
222 * and numdirtybuffers is now reasonable, wake them up.
226 numdirtywakeup(int level)
228 if (numdirtybuffers <= level) {
229 if (needsbuffer & VFS_BIO_NEED_DIRTYFLUSH) {
230 needsbuffer &= ~VFS_BIO_NEED_DIRTYFLUSH;
231 wakeup(&needsbuffer);
239 * Called when buffer space is potentially available for recovery.
240 * getnewbuf() will block on this flag when it is unable to free
241 * sufficient buffer space. Buffer space becomes recoverable when
242 * bp's get placed back in the queues.
249 * If someone is waiting for BUF space, wake them up. Even
250 * though we haven't freed the kva space yet, the waiting
251 * process will be able to now.
253 if (needsbuffer & VFS_BIO_NEED_BUFSPACE) {
254 needsbuffer &= ~VFS_BIO_NEED_BUFSPACE;
255 wakeup(&needsbuffer);
260 * runningbufwakeup() - in-progress I/O accounting.
264 runningbufwakeup(struct buf *bp)
266 if (bp->b_runningbufspace) {
267 runningbufspace -= bp->b_runningbufspace;
268 bp->b_runningbufspace = 0;
269 if (runningbufreq && runningbufspace <= lorunningspace) {
271 wakeup(&runningbufreq);
279 * Called when a buffer has been added to one of the free queues to
280 * account for the buffer and to wakeup anyone waiting for free buffers.
281 * This typically occurs when large amounts of metadata are being handled
282 * by the buffer cache ( else buffer space runs out first, usually ).
290 needsbuffer &= ~VFS_BIO_NEED_ANY;
291 if (numfreebuffers >= hifreebuffers)
292 needsbuffer &= ~VFS_BIO_NEED_FREE;
293 wakeup(&needsbuffer);
298 * waitrunningbufspace()
300 * runningbufspace is a measure of the amount of I/O currently
301 * running. This routine is used in async-write situations to
302 * prevent creating huge backups of pending writes to a device.
303 * Only asynchronous writes are governed by this function.
305 * Reads will adjust runningbufspace, but will not block based on it.
306 * The read load has a side effect of reducing the allowed write load.
308 * This does NOT turn an async write into a sync write. It waits
309 * for earlier writes to complete and generally returns before the
310 * caller's write has reached the device.
313 waitrunningbufspace(void)
315 while (runningbufspace > hirunningspace) {
318 s = splbio(); /* fix race against interrupt/biodone() */
320 tsleep(&runningbufreq, 0, "wdrain", 0);
326 * vfs_buf_test_cache:
328 * Called when a buffer is extended. This function clears the B_CACHE
329 * bit if the newly extended portion of the buffer does not contain
334 vfs_buf_test_cache(struct buf *bp,
335 vm_ooffset_t foff, vm_offset_t off, vm_offset_t size,
338 if (bp->b_flags & B_CACHE) {
339 int base = (foff + off) & PAGE_MASK;
340 if (vm_page_is_valid(m, base, size) == 0)
341 bp->b_flags &= ~B_CACHE;
347 bd_wakeup(int dirtybuflevel)
349 if (bd_request == 0 && numdirtybuffers >= dirtybuflevel) {
356 * bd_speedup - speedup the buffer cache flushing code
367 * Initialize buffer headers and related structures.
371 bufhashinit(caddr_t vaddr)
373 /* first, make a null hash table */
375 for (bufhashmask = 8; bufhashmask < nbuf / 4; bufhashmask <<= 1)
377 bufhashtbl = (void *)vaddr;
378 vaddr = vaddr + sizeof(*bufhashtbl) * bufhashmask;
389 TAILQ_INIT(&bswlist);
390 LIST_INIT(&invalhash);
391 lwkt_token_init(&buftimetoken);
393 for (i = 0; i <= bufhashmask; i++)
394 LIST_INIT(&bufhashtbl[i]);
396 /* next, make a null set of free lists */
397 for (i = 0; i < BUFFER_QUEUES; i++)
398 TAILQ_INIT(&bufqueues[i]);
400 /* finally, initialize each buffer header and stick on empty q */
401 for (i = 0; i < nbuf; i++) {
403 bzero(bp, sizeof *bp);
404 bp->b_flags = B_INVAL; /* we're just an empty header */
406 bp->b_qindex = QUEUE_EMPTY;
408 xio_init(&bp->b_xio);
409 LIST_INIT(&bp->b_dep);
411 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_EMPTY], bp, b_freelist);
412 LIST_INSERT_HEAD(&invalhash, bp, b_hash);
416 * maxbufspace is the absolute maximum amount of buffer space we are
417 * allowed to reserve in KVM and in real terms. The absolute maximum
418 * is nominally used by buf_daemon. hibufspace is the nominal maximum
419 * used by most other processes. The differential is required to
420 * ensure that buf_daemon is able to run when other processes might
421 * be blocked waiting for buffer space.
423 * maxbufspace is based on BKVASIZE. Allocating buffers larger then
424 * this may result in KVM fragmentation which is not handled optimally
427 maxbufspace = nbuf * BKVASIZE;
428 hibufspace = imax(3 * maxbufspace / 4, maxbufspace - MAXBSIZE * 10);
429 lobufspace = hibufspace - MAXBSIZE;
431 lorunningspace = 512 * 1024;
432 hirunningspace = 1024 * 1024;
435 * Limit the amount of malloc memory since it is wired permanently into
436 * the kernel space. Even though this is accounted for in the buffer
437 * allocation, we don't want the malloced region to grow uncontrolled.
438 * The malloc scheme improves memory utilization significantly on average
439 * (small) directories.
441 maxbufmallocspace = hibufspace / 20;
444 * Reduce the chance of a deadlock occuring by limiting the number
445 * of delayed-write dirty buffers we allow to stack up.
447 hidirtybuffers = nbuf / 4 + 20;
450 * To support extreme low-memory systems, make sure hidirtybuffers cannot
451 * eat up all available buffer space. This occurs when our minimum cannot
452 * be met. We try to size hidirtybuffers to 3/4 our buffer space assuming
453 * BKVASIZE'd (8K) buffers.
455 while (hidirtybuffers * BKVASIZE > 3 * hibufspace / 4) {
456 hidirtybuffers >>= 1;
458 lodirtybuffers = hidirtybuffers / 2;
461 * Try to keep the number of free buffers in the specified range,
462 * and give special processes (e.g. like buf_daemon) access to an
465 lofreebuffers = nbuf / 18 + 5;
466 hifreebuffers = 2 * lofreebuffers;
467 numfreebuffers = nbuf;
470 * Maximum number of async ops initiated per buf_daemon loop. This is
471 * somewhat of a hack at the moment, we really need to limit ourselves
472 * based on the number of bytes of I/O in-transit that were initiated
476 bogus_offset = kmem_alloc_pageable(kernel_map, PAGE_SIZE);
477 bogus_page = vm_page_alloc(kernel_object,
478 ((bogus_offset - VM_MIN_KERNEL_ADDRESS) >> PAGE_SHIFT),
480 vmstats.v_wire_count++;
485 * bfreekva() - free the kva allocation for a buffer.
487 * Must be called at splbio() or higher as this is the only locking for
490 * Since this call frees up buffer space, we call bufspacewakeup().
493 bfreekva(struct buf * bp)
499 count = vm_map_entry_reserve(MAP_RESERVE_COUNT);
500 vm_map_lock(buffer_map);
501 bufspace -= bp->b_kvasize;
502 vm_map_delete(buffer_map,
503 (vm_offset_t) bp->b_kvabase,
504 (vm_offset_t) bp->b_kvabase + bp->b_kvasize,
507 vm_map_unlock(buffer_map);
508 vm_map_entry_release(count);
517 * Remove the buffer from the appropriate free list.
520 bremfree(struct buf * bp)
523 int old_qindex = bp->b_qindex;
525 if (bp->b_qindex != QUEUE_NONE) {
526 KASSERT(BUF_REFCNTNB(bp) == 1,
527 ("bremfree: bp %p not locked",bp));
528 TAILQ_REMOVE(&bufqueues[bp->b_qindex], bp, b_freelist);
529 bp->b_qindex = QUEUE_NONE;
531 if (BUF_REFCNTNB(bp) <= 1)
532 panic("bremfree: removing a buffer not on a queue");
536 * Fixup numfreebuffers count. If the buffer is invalid or not
537 * delayed-write, and it was on the EMPTY, LRU, or AGE queues,
538 * the buffer was free and we must decrement numfreebuffers.
540 if ((bp->b_flags & B_INVAL) || (bp->b_flags & B_DELWRI) == 0) {
557 * Get a buffer with the specified data. Look in the cache first. We
558 * must clear B_ERROR and B_INVAL prior to initiating I/O. If B_CACHE
559 * is set, the buffer is valid and we do not have to do anything ( see
563 bread(struct vnode * vp, daddr_t blkno, int size, struct buf ** bpp)
567 bp = getblk(vp, blkno, size, 0, 0);
570 /* if not found in cache, do some I/O */
571 if ((bp->b_flags & B_CACHE) == 0) {
572 KASSERT(!(bp->b_flags & B_ASYNC), ("bread: illegal async bp %p", bp));
573 bp->b_flags |= B_READ;
574 bp->b_flags &= ~(B_ERROR | B_INVAL);
575 vfs_busy_pages(bp, 0);
576 VOP_STRATEGY(vp, bp);
577 return (biowait(bp));
583 * Operates like bread, but also starts asynchronous I/O on
584 * read-ahead blocks. We must clear B_ERROR and B_INVAL prior
585 * to initiating I/O . If B_CACHE is set, the buffer is valid
586 * and we do not have to do anything.
589 breadn(struct vnode * vp, daddr_t blkno, int size, daddr_t * rablkno,
590 int *rabsize, int cnt, struct buf ** bpp)
592 struct buf *bp, *rabp;
594 int rv = 0, readwait = 0;
596 *bpp = bp = getblk(vp, blkno, size, 0, 0);
598 /* if not found in cache, do some I/O */
599 if ((bp->b_flags & B_CACHE) == 0) {
600 bp->b_flags |= B_READ;
601 bp->b_flags &= ~(B_ERROR | B_INVAL);
602 vfs_busy_pages(bp, 0);
603 VOP_STRATEGY(vp, bp);
607 for (i = 0; i < cnt; i++, rablkno++, rabsize++) {
608 if (inmem(vp, *rablkno))
610 rabp = getblk(vp, *rablkno, *rabsize, 0, 0);
612 if ((rabp->b_flags & B_CACHE) == 0) {
613 rabp->b_flags |= B_READ | B_ASYNC;
614 rabp->b_flags &= ~(B_ERROR | B_INVAL);
615 vfs_busy_pages(rabp, 0);
617 VOP_STRATEGY(vp, rabp);
630 * Write, release buffer on completion. (Done by iodone
631 * if async). Do not bother writing anything if the buffer
634 * Note that we set B_CACHE here, indicating that buffer is
635 * fully valid and thus cacheable. This is true even of NFS
636 * now so we set it generally. This could be set either here
637 * or in biodone() since the I/O is synchronous. We put it
641 bwrite(struct buf * bp)
646 if (bp->b_flags & B_INVAL) {
651 oldflags = bp->b_flags;
653 if (BUF_REFCNTNB(bp) == 0)
654 panic("bwrite: buffer is not busy???");
657 * If a background write is already in progress, delay
658 * writing this block if it is asynchronous. Otherwise
659 * wait for the background write to complete.
661 if (bp->b_xflags & BX_BKGRDINPROG) {
662 if (bp->b_flags & B_ASYNC) {
667 bp->b_xflags |= BX_BKGRDWAIT;
668 tsleep(&bp->b_xflags, 0, "biord", 0);
669 if (bp->b_xflags & BX_BKGRDINPROG)
670 panic("bwrite: still writing");
673 /* Mark the buffer clean */
677 * If this buffer is marked for background writing and we
678 * do not have to wait for it, make a copy and write the
679 * copy so as to leave this buffer ready for further use.
681 * This optimization eats a lot of memory. If we have a page
682 * or buffer shortfull we can't do it.
685 (bp->b_xflags & BX_BKGRDWRITE) &&
686 (bp->b_flags & B_ASYNC) &&
687 !vm_page_count_severe() &&
688 !buf_dirty_count_severe()) {
689 if (bp->b_flags & B_CALL)
690 panic("bwrite: need chained iodone");
692 /* get a new block */
693 newbp = geteblk(bp->b_bufsize);
695 /* set it to be identical to the old block */
696 memcpy(newbp->b_data, bp->b_data, bp->b_bufsize);
697 bgetvp(bp->b_vp, newbp);
698 newbp->b_lblkno = bp->b_lblkno;
699 newbp->b_blkno = bp->b_blkno;
700 newbp->b_offset = bp->b_offset;
701 newbp->b_iodone = vfs_backgroundwritedone;
702 newbp->b_flags |= B_ASYNC | B_CALL;
703 newbp->b_flags &= ~B_INVAL;
705 /* move over the dependencies */
706 if (LIST_FIRST(&bp->b_dep) != NULL && bioops.io_movedeps)
707 (*bioops.io_movedeps)(bp, newbp);
710 * Initiate write on the copy, release the original to
711 * the B_LOCKED queue so that it cannot go away until
712 * the background write completes. If not locked it could go
713 * away and then be reconstituted while it was being written.
714 * If the reconstituted buffer were written, we could end up
715 * with two background copies being written at the same time.
717 bp->b_xflags |= BX_BKGRDINPROG;
718 bp->b_flags |= B_LOCKED;
723 bp->b_flags &= ~(B_READ | B_DONE | B_ERROR);
724 bp->b_flags |= B_WRITEINPROG | B_CACHE;
726 bp->b_vp->v_numoutput++;
727 vfs_busy_pages(bp, 1);
730 * Normal bwrites pipeline writes
732 bp->b_runningbufspace = bp->b_bufsize;
733 runningbufspace += bp->b_runningbufspace;
736 if (oldflags & B_ASYNC)
738 VOP_STRATEGY(bp->b_vp, bp);
740 if ((oldflags & B_ASYNC) == 0) {
741 int rtval = biowait(bp);
744 } else if ((oldflags & B_NOWDRAIN) == 0) {
746 * don't allow the async write to saturate the I/O
747 * system. Deadlocks can occur only if a device strategy
748 * routine (like in VN) turns around and issues another
749 * high-level write, in which case B_NOWDRAIN is expected
750 * to be set. Otherwise we will not deadlock here because
751 * we are blocking waiting for I/O that is already in-progress
754 waitrunningbufspace();
761 * Complete a background write started from bwrite.
764 vfs_backgroundwritedone(struct buf *bp)
769 * Find the original buffer that we are writing.
771 if ((origbp = gbincore(bp->b_vp, bp->b_lblkno)) == NULL)
772 panic("backgroundwritedone: lost buffer");
774 * Process dependencies then return any unfinished ones.
776 if (LIST_FIRST(&bp->b_dep) != NULL && bioops.io_complete)
777 (*bioops.io_complete)(bp);
778 if (LIST_FIRST(&bp->b_dep) != NULL && bioops.io_movedeps)
779 (*bioops.io_movedeps)(bp, origbp);
781 * Clear the BX_BKGRDINPROG flag in the original buffer
782 * and awaken it if it is waiting for the write to complete.
783 * If BX_BKGRDINPROG is not set in the original buffer it must
784 * have been released and re-instantiated - which is not legal.
786 KASSERT((origbp->b_xflags & BX_BKGRDINPROG), ("backgroundwritedone: lost buffer2"));
787 origbp->b_xflags &= ~BX_BKGRDINPROG;
788 if (origbp->b_xflags & BX_BKGRDWAIT) {
789 origbp->b_xflags &= ~BX_BKGRDWAIT;
790 wakeup(&origbp->b_xflags);
793 * Clear the B_LOCKED flag and remove it from the locked
794 * queue if it currently resides there.
796 origbp->b_flags &= ~B_LOCKED;
797 if (BUF_LOCK(origbp, LK_EXCLUSIVE | LK_NOWAIT) == 0) {
802 * This buffer is marked B_NOCACHE, so when it is released
803 * by biodone, it will be tossed. We mark it with B_READ
804 * to avoid biodone doing a second vwakeup.
806 bp->b_flags |= B_NOCACHE | B_READ;
807 bp->b_flags &= ~(B_CACHE | B_CALL | B_DONE);
813 * Delayed write. (Buffer is marked dirty). Do not bother writing
814 * anything if the buffer is marked invalid.
816 * Note that since the buffer must be completely valid, we can safely
817 * set B_CACHE. In fact, we have to set B_CACHE here rather then in
818 * biodone() in order to prevent getblk from writing the buffer
822 bdwrite(struct buf *bp)
824 if (BUF_REFCNTNB(bp) == 0)
825 panic("bdwrite: buffer is not busy");
827 if (bp->b_flags & B_INVAL) {
834 * Set B_CACHE, indicating that the buffer is fully valid. This is
835 * true even of NFS now.
837 bp->b_flags |= B_CACHE;
840 * This bmap keeps the system from needing to do the bmap later,
841 * perhaps when the system is attempting to do a sync. Since it
842 * is likely that the indirect block -- or whatever other datastructure
843 * that the filesystem needs is still in memory now, it is a good
844 * thing to do this. Note also, that if the pageout daemon is
845 * requesting a sync -- there might not be enough memory to do
846 * the bmap then... So, this is important to do.
848 if (bp->b_lblkno == bp->b_blkno) {
849 VOP_BMAP(bp->b_vp, bp->b_lblkno, NULL, &bp->b_blkno, NULL, NULL);
853 * Set the *dirty* buffer range based upon the VM system dirty pages.
858 * We need to do this here to satisfy the vnode_pager and the
859 * pageout daemon, so that it thinks that the pages have been
860 * "cleaned". Note that since the pages are in a delayed write
861 * buffer -- the VFS layer "will" see that the pages get written
862 * out on the next sync, or perhaps the cluster will be completed.
868 * Wakeup the buffer flushing daemon if we have a lot of dirty
869 * buffers (midpoint between our recovery point and our stall
872 bd_wakeup((lodirtybuffers + hidirtybuffers) / 2);
875 * note: we cannot initiate I/O from a bdwrite even if we wanted to,
876 * due to the softdep code.
883 * Turn buffer into delayed write request. We must clear B_READ and
884 * B_RELBUF, and we must set B_DELWRI. We reassign the buffer to
885 * itself to properly update it in the dirty/clean lists. We mark it
886 * B_DONE to ensure that any asynchronization of the buffer properly
887 * clears B_DONE ( else a panic will occur later ).
889 * bdirty() is kinda like bdwrite() - we have to clear B_INVAL which
890 * might have been set pre-getblk(). Unlike bwrite/bdwrite, bdirty()
891 * should only be called if the buffer is known-good.
893 * Since the buffer is not on a queue, we do not update the numfreebuffers
896 * Must be called at splbio().
897 * The buffer must be on QUEUE_NONE.
900 bdirty(struct buf *bp)
902 KASSERT(bp->b_qindex == QUEUE_NONE, ("bdirty: buffer %p still on queue %d", bp, bp->b_qindex));
903 bp->b_flags &= ~(B_READ|B_RELBUF);
905 if ((bp->b_flags & B_DELWRI) == 0) {
906 bp->b_flags |= B_DONE | B_DELWRI;
907 reassignbuf(bp, bp->b_vp);
909 bd_wakeup((lodirtybuffers + hidirtybuffers) / 2);
916 * Clear B_DELWRI for buffer.
918 * Since the buffer is not on a queue, we do not update the numfreebuffers
921 * Must be called at splbio().
922 * The buffer must be on QUEUE_NONE.
926 bundirty(struct buf *bp)
928 KASSERT(bp->b_qindex == QUEUE_NONE, ("bundirty: buffer %p still on queue %d", bp, bp->b_qindex));
930 if (bp->b_flags & B_DELWRI) {
931 bp->b_flags &= ~B_DELWRI;
932 reassignbuf(bp, bp->b_vp);
934 numdirtywakeup(lodirtybuffers);
937 * Since it is now being written, we can clear its deferred write flag.
939 bp->b_flags &= ~B_DEFERRED;
945 * Asynchronous write. Start output on a buffer, but do not wait for
946 * it to complete. The buffer is released when the output completes.
948 * bwrite() ( or the VOP routine anyway ) is responsible for handling
949 * B_INVAL buffers. Not us.
952 bawrite(struct buf * bp)
954 bp->b_flags |= B_ASYNC;
955 (void) VOP_BWRITE(bp->b_vp, bp);
961 * Ordered write. Start output on a buffer, and flag it so that the
962 * device will write it in the order it was queued. The buffer is
963 * released when the output completes. bwrite() ( or the VOP routine
964 * anyway ) is responsible for handling B_INVAL buffers.
967 bowrite(struct buf * bp)
969 bp->b_flags |= B_ORDERED | B_ASYNC;
970 return (VOP_BWRITE(bp->b_vp, bp));
976 * Called prior to the locking of any vnodes when we are expecting to
977 * write. We do not want to starve the buffer cache with too many
978 * dirty buffers so we block here. By blocking prior to the locking
979 * of any vnodes we attempt to avoid the situation where a locked vnode
980 * prevents the various system daemons from flushing related buffers.
986 if (numdirtybuffers >= hidirtybuffers) {
990 while (numdirtybuffers >= hidirtybuffers) {
992 needsbuffer |= VFS_BIO_NEED_DIRTYFLUSH;
993 tsleep(&needsbuffer, 0, "flswai", 0);
1000 * Return true if we have too many dirty buffers.
1003 buf_dirty_count_severe(void)
1005 return(numdirtybuffers >= hidirtybuffers);
1011 * Release a busy buffer and, if requested, free its resources. The
1012 * buffer will be stashed in the appropriate bufqueue[] allowing it
1013 * to be accessed later as a cache entity or reused for other purposes.
1016 brelse(struct buf * bp)
1020 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)), ("brelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp));
1024 if (bp->b_flags & B_LOCKED)
1025 bp->b_flags &= ~B_ERROR;
1027 if ((bp->b_flags & (B_READ | B_ERROR | B_INVAL)) == B_ERROR) {
1029 * Failed write, redirty. Must clear B_ERROR to prevent
1030 * pages from being scrapped. If B_INVAL is set then
1031 * this case is not run and the next case is run to
1032 * destroy the buffer. B_INVAL can occur if the buffer
1033 * is outside the range supported by the underlying device.
1035 bp->b_flags &= ~B_ERROR;
1037 } else if ((bp->b_flags & (B_NOCACHE | B_INVAL | B_ERROR | B_FREEBUF)) ||
1038 (bp->b_bufsize <= 0)) {
1040 * Either a failed I/O or we were asked to free or not
1043 bp->b_flags |= B_INVAL;
1044 if (LIST_FIRST(&bp->b_dep) != NULL && bioops.io_deallocate)
1045 (*bioops.io_deallocate)(bp);
1046 if (bp->b_flags & B_DELWRI) {
1048 numdirtywakeup(lodirtybuffers);
1050 bp->b_flags &= ~(B_DELWRI | B_CACHE | B_FREEBUF);
1051 if ((bp->b_flags & B_VMIO) == 0) {
1060 * We must clear B_RELBUF if B_DELWRI is set. If vfs_vmio_release()
1061 * is called with B_DELWRI set, the underlying pages may wind up
1062 * getting freed causing a previous write (bdwrite()) to get 'lost'
1063 * because pages associated with a B_DELWRI bp are marked clean.
1065 * We still allow the B_INVAL case to call vfs_vmio_release(), even
1066 * if B_DELWRI is set.
1068 * If B_DELWRI is not set we may have to set B_RELBUF if we are low
1069 * on pages to return pages to the VM page queues.
1071 if (bp->b_flags & B_DELWRI)
1072 bp->b_flags &= ~B_RELBUF;
1073 else if (vm_page_count_severe() && !(bp->b_xflags & BX_BKGRDINPROG))
1074 bp->b_flags |= B_RELBUF;
1077 * VMIO buffer rundown. It is not very necessary to keep a VMIO buffer
1078 * constituted, not even NFS buffers now. Two flags effect this. If
1079 * B_INVAL, the struct buf is invalidated but the VM object is kept
1080 * around ( i.e. so it is trivial to reconstitute the buffer later ).
1082 * If B_ERROR or B_NOCACHE is set, pages in the VM object will be
1083 * invalidated. B_ERROR cannot be set for a failed write unless the
1084 * buffer is also B_INVAL because it hits the re-dirtying code above.
1086 * Normally we can do this whether a buffer is B_DELWRI or not. If
1087 * the buffer is an NFS buffer, it is tracking piecemeal writes or
1088 * the commit state and we cannot afford to lose the buffer. If the
1089 * buffer has a background write in progress, we need to keep it
1090 * around to prevent it from being reconstituted and starting a second
1093 if ((bp->b_flags & B_VMIO)
1094 && !(bp->b_vp->v_tag == VT_NFS &&
1095 !vn_isdisk(bp->b_vp, NULL) &&
1096 (bp->b_flags & B_DELWRI))
1109 * Get the base offset and length of the buffer. Note that
1110 * in the VMIO case if the buffer block size is not
1111 * page-aligned then b_data pointer may not be page-aligned.
1112 * But our b_xio.xio_pages array *IS* page aligned.
1114 * block sizes less then DEV_BSIZE (usually 512) are not
1115 * supported due to the page granularity bits (m->valid,
1116 * m->dirty, etc...).
1118 * See man buf(9) for more information
1121 resid = bp->b_bufsize;
1122 foff = bp->b_offset;
1124 for (i = 0; i < bp->b_xio.xio_npages; i++) {
1125 m = bp->b_xio.xio_pages[i];
1126 vm_page_flag_clear(m, PG_ZERO);
1128 * If we hit a bogus page, fixup *all* of them
1129 * now. Note that we left these pages wired
1130 * when we removed them so they had better exist,
1131 * and they cannot be ripped out from under us so
1132 * no splvm() protection is necessary.
1134 if (m == bogus_page) {
1135 VOP_GETVOBJECT(vp, &obj);
1136 poff = OFF_TO_IDX(bp->b_offset);
1138 for (j = i; j < bp->b_xio.xio_npages; j++) {
1141 mtmp = bp->b_xio.xio_pages[j];
1142 if (mtmp == bogus_page) {
1143 mtmp = vm_page_lookup(obj, poff + j);
1145 panic("brelse: page missing");
1147 bp->b_xio.xio_pages[j] = mtmp;
1151 if ((bp->b_flags & B_INVAL) == 0) {
1152 pmap_qenter(trunc_page((vm_offset_t)bp->b_data),
1153 bp->b_xio.xio_pages, bp->b_xio.xio_npages);
1155 m = bp->b_xio.xio_pages[i];
1159 * Invalidate the backing store if B_NOCACHE is set
1160 * (e.g. used with vinvalbuf()). If this is NFS
1161 * we impose a requirement that the block size be
1162 * a multiple of PAGE_SIZE and create a temporary
1163 * hack to basically invalidate the whole page. The
1164 * problem is that NFS uses really odd buffer sizes
1165 * especially when tracking piecemeal writes and
1166 * it also vinvalbuf()'s a lot, which would result
1167 * in only partial page validation and invalidation
1168 * here. If the file page is mmap()'d, however,
1169 * all the valid bits get set so after we invalidate
1170 * here we would end up with weird m->valid values
1171 * like 0xfc. nfs_getpages() can't handle this so
1172 * we clear all the valid bits for the NFS case
1173 * instead of just some of them.
1175 * The real bug is the VM system having to set m->valid
1176 * to VM_PAGE_BITS_ALL for faulted-in pages, which
1177 * itself is an artifact of the whole 512-byte
1178 * granular mess that exists to support odd block
1179 * sizes and UFS meta-data block sizes (e.g. 6144).
1180 * A complete rewrite is required.
1182 if (bp->b_flags & (B_NOCACHE|B_ERROR)) {
1183 int poffset = foff & PAGE_MASK;
1186 presid = PAGE_SIZE - poffset;
1187 if (bp->b_vp->v_tag == VT_NFS &&
1188 bp->b_vp->v_type == VREG) {
1190 } else if (presid > resid) {
1193 KASSERT(presid >= 0, ("brelse: extra page"));
1194 vm_page_set_invalid(m, poffset, presid);
1196 resid -= PAGE_SIZE - (foff & PAGE_MASK);
1197 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK;
1200 if (bp->b_flags & (B_INVAL | B_RELBUF))
1201 vfs_vmio_release(bp);
1203 } else if (bp->b_flags & B_VMIO) {
1205 if (bp->b_flags & (B_INVAL | B_RELBUF))
1206 vfs_vmio_release(bp);
1210 if (bp->b_qindex != QUEUE_NONE)
1211 panic("brelse: free buffer onto another queue???");
1212 if (BUF_REFCNTNB(bp) > 1) {
1213 /* Temporary panic to verify exclusive locking */
1214 /* This panic goes away when we allow shared refs */
1215 panic("brelse: multiple refs");
1216 /* do not release to free list */
1224 /* buffers with no memory */
1225 if (bp->b_bufsize == 0) {
1226 bp->b_flags |= B_INVAL;
1227 bp->b_xflags &= ~BX_BKGRDWRITE;
1228 if (bp->b_xflags & BX_BKGRDINPROG)
1229 panic("losing buffer 1");
1230 if (bp->b_kvasize) {
1231 bp->b_qindex = QUEUE_EMPTYKVA;
1233 bp->b_qindex = QUEUE_EMPTY;
1235 TAILQ_INSERT_HEAD(&bufqueues[bp->b_qindex], bp, b_freelist);
1236 LIST_REMOVE(bp, b_hash);
1237 LIST_INSERT_HEAD(&invalhash, bp, b_hash);
1239 /* buffers with junk contents */
1240 } else if (bp->b_flags & (B_ERROR | B_INVAL | B_NOCACHE | B_RELBUF)) {
1241 bp->b_flags |= B_INVAL;
1242 bp->b_xflags &= ~BX_BKGRDWRITE;
1243 if (bp->b_xflags & BX_BKGRDINPROG)
1244 panic("losing buffer 2");
1245 bp->b_qindex = QUEUE_CLEAN;
1246 TAILQ_INSERT_HEAD(&bufqueues[QUEUE_CLEAN], bp, b_freelist);
1247 LIST_REMOVE(bp, b_hash);
1248 LIST_INSERT_HEAD(&invalhash, bp, b_hash);
1251 /* buffers that are locked */
1252 } else if (bp->b_flags & B_LOCKED) {
1253 bp->b_qindex = QUEUE_LOCKED;
1254 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_LOCKED], bp, b_freelist);
1256 /* remaining buffers */
1258 switch(bp->b_flags & (B_DELWRI|B_AGE)) {
1259 case B_DELWRI | B_AGE:
1260 bp->b_qindex = QUEUE_DIRTY;
1261 TAILQ_INSERT_HEAD(&bufqueues[QUEUE_DIRTY], bp, b_freelist);
1264 bp->b_qindex = QUEUE_DIRTY;
1265 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_DIRTY], bp, b_freelist);
1268 bp->b_qindex = QUEUE_CLEAN;
1269 TAILQ_INSERT_HEAD(&bufqueues[QUEUE_CLEAN], bp, b_freelist);
1272 bp->b_qindex = QUEUE_CLEAN;
1273 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_CLEAN], bp, b_freelist);
1279 * If B_INVAL, clear B_DELWRI. We've already placed the buffer
1280 * on the correct queue.
1282 if ((bp->b_flags & (B_INVAL|B_DELWRI)) == (B_INVAL|B_DELWRI))
1286 * Fixup numfreebuffers count. The bp is on an appropriate queue
1287 * unless locked. We then bump numfreebuffers if it is not B_DELWRI.
1288 * We've already handled the B_INVAL case ( B_DELWRI will be clear
1289 * if B_INVAL is set ).
1292 if ((bp->b_flags & B_LOCKED) == 0 && !(bp->b_flags & B_DELWRI))
1296 * Something we can maybe free or reuse
1298 if (bp->b_bufsize || bp->b_kvasize)
1303 bp->b_flags &= ~(B_ORDERED | B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF |
1304 B_DIRECT | B_NOWDRAIN);
1309 * Release a buffer back to the appropriate queue but do not try to free
1310 * it. The buffer is expected to be used again soon.
1312 * bqrelse() is used by bdwrite() to requeue a delayed write, and used by
1313 * biodone() to requeue an async I/O on completion. It is also used when
1314 * known good buffers need to be requeued but we think we may need the data
1317 * XXX we should be able to leave the B_RELBUF hint set on completion.
1320 bqrelse(struct buf * bp)
1326 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)), ("bqrelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp));
1328 if (bp->b_qindex != QUEUE_NONE)
1329 panic("bqrelse: free buffer onto another queue???");
1330 if (BUF_REFCNTNB(bp) > 1) {
1331 /* do not release to free list */
1332 panic("bqrelse: multiple refs");
1337 if (bp->b_flags & B_LOCKED) {
1338 bp->b_flags &= ~B_ERROR;
1339 bp->b_qindex = QUEUE_LOCKED;
1340 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_LOCKED], bp, b_freelist);
1341 /* buffers with stale but valid contents */
1342 } else if (bp->b_flags & B_DELWRI) {
1343 bp->b_qindex = QUEUE_DIRTY;
1344 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_DIRTY], bp, b_freelist);
1345 } else if (vm_page_count_severe()) {
1347 * We are too low on memory, we have to try to free the
1348 * buffer (most importantly: the wired pages making up its
1349 * backing store) *now*.
1355 bp->b_qindex = QUEUE_CLEAN;
1356 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_CLEAN], bp, b_freelist);
1359 if ((bp->b_flags & B_LOCKED) == 0 &&
1360 ((bp->b_flags & B_INVAL) || !(bp->b_flags & B_DELWRI))) {
1365 * Something we can maybe free or reuse.
1367 if (bp->b_bufsize && !(bp->b_flags & B_DELWRI))
1372 bp->b_flags &= ~(B_ORDERED | B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF);
1377 vfs_vmio_release(struct buf *bp)
1383 for (i = 0; i < bp->b_xio.xio_npages; i++) {
1384 m = bp->b_xio.xio_pages[i];
1385 bp->b_xio.xio_pages[i] = NULL;
1387 * In order to keep page LRU ordering consistent, put
1388 * everything on the inactive queue.
1390 vm_page_unwire(m, 0);
1392 * We don't mess with busy pages, it is
1393 * the responsibility of the process that
1394 * busied the pages to deal with them.
1396 if ((m->flags & PG_BUSY) || (m->busy != 0))
1399 if (m->wire_count == 0) {
1400 vm_page_flag_clear(m, PG_ZERO);
1402 * Might as well free the page if we can and it has
1403 * no valid data. We also free the page if the
1404 * buffer was used for direct I/O.
1406 if ((bp->b_flags & B_ASYNC) == 0 && !m->valid && m->hold_count == 0) {
1408 vm_page_protect(m, VM_PROT_NONE);
1410 } else if (bp->b_flags & B_DIRECT) {
1411 vm_page_try_to_free(m);
1412 } else if (vm_page_count_severe()) {
1413 vm_page_try_to_cache(m);
1418 pmap_qremove(trunc_page((vm_offset_t) bp->b_data), bp->b_xio.xio_npages);
1419 if (bp->b_bufsize) {
1423 bp->b_xio.xio_npages = 0;
1424 bp->b_flags &= ~B_VMIO;
1430 * Check to see if a block is currently memory resident.
1433 gbincore(struct vnode * vp, daddr_t blkno)
1436 struct bufhashhdr *bh;
1438 bh = bufhash(vp, blkno);
1440 /* Search hash chain */
1441 LIST_FOREACH(bp, bh, b_hash) {
1443 if (bp->b_vp == vp && bp->b_lblkno == blkno &&
1444 (bp->b_flags & B_INVAL) == 0) {
1454 * Implement clustered async writes for clearing out B_DELWRI buffers.
1455 * This is much better then the old way of writing only one buffer at
1456 * a time. Note that we may not be presented with the buffers in the
1457 * correct order, so we search for the cluster in both directions.
1460 vfs_bio_awrite(struct buf * bp)
1464 daddr_t lblkno = bp->b_lblkno;
1465 struct vnode *vp = bp->b_vp;
1475 * right now we support clustered writing only to regular files. If
1476 * we find a clusterable block we could be in the middle of a cluster
1477 * rather then at the beginning.
1479 if ((vp->v_type == VREG) &&
1480 (vp->v_mount != 0) && /* Only on nodes that have the size info */
1481 (bp->b_flags & (B_CLUSTEROK | B_INVAL)) == B_CLUSTEROK) {
1483 size = vp->v_mount->mnt_stat.f_iosize;
1484 maxcl = MAXPHYS / size;
1486 for (i = 1; i < maxcl; i++) {
1487 if ((bpa = gbincore(vp, lblkno + i)) &&
1488 BUF_REFCNT(bpa) == 0 &&
1489 ((bpa->b_flags & (B_DELWRI | B_CLUSTEROK | B_INVAL)) ==
1490 (B_DELWRI | B_CLUSTEROK)) &&
1491 (bpa->b_bufsize == size)) {
1492 if ((bpa->b_blkno == bpa->b_lblkno) ||
1494 bp->b_blkno + ((i * size) >> DEV_BSHIFT)))
1500 for (j = 1; i + j <= maxcl && j <= lblkno; j++) {
1501 if ((bpa = gbincore(vp, lblkno - j)) &&
1502 BUF_REFCNT(bpa) == 0 &&
1503 ((bpa->b_flags & (B_DELWRI | B_CLUSTEROK | B_INVAL)) ==
1504 (B_DELWRI | B_CLUSTEROK)) &&
1505 (bpa->b_bufsize == size)) {
1506 if ((bpa->b_blkno == bpa->b_lblkno) ||
1508 bp->b_blkno - ((j * size) >> DEV_BSHIFT)))
1517 * this is a possible cluster write
1520 nwritten = cluster_wbuild(vp, size, lblkno - j, ncl);
1526 BUF_LOCK(bp, LK_EXCLUSIVE);
1528 bp->b_flags |= B_ASYNC;
1532 * default (old) behavior, writing out only one block
1534 * XXX returns b_bufsize instead of b_bcount for nwritten?
1536 nwritten = bp->b_bufsize;
1537 (void) VOP_BWRITE(bp->b_vp, bp);
1545 * Find and initialize a new buffer header, freeing up existing buffers
1546 * in the bufqueues as necessary. The new buffer is returned locked.
1548 * Important: B_INVAL is not set. If the caller wishes to throw the
1549 * buffer away, the caller must set B_INVAL prior to calling brelse().
1552 * We have insufficient buffer headers
1553 * We have insufficient buffer space
1554 * buffer_map is too fragmented ( space reservation fails )
1555 * If we have to flush dirty buffers ( but we try to avoid this )
1557 * To avoid VFS layer recursion we do not flush dirty buffers ourselves.
1558 * Instead we ask the buf daemon to do it for us. We attempt to
1559 * avoid piecemeal wakeups of the pageout daemon.
1563 getnewbuf(int slpflag, int slptimeo, int size, int maxsize)
1569 static int flushingbufs;
1572 * We can't afford to block since we might be holding a vnode lock,
1573 * which may prevent system daemons from running. We deal with
1574 * low-memory situations by proactively returning memory and running
1575 * async I/O rather then sync I/O.
1579 --getnewbufrestarts;
1581 ++getnewbufrestarts;
1584 * Setup for scan. If we do not have enough free buffers,
1585 * we setup a degenerate case that immediately fails. Note
1586 * that if we are specially marked process, we are allowed to
1587 * dip into our reserves.
1589 * The scanning sequence is nominally: EMPTY->EMPTYKVA->CLEAN
1591 * We start with EMPTYKVA. If the list is empty we backup to EMPTY.
1592 * However, there are a number of cases (defragging, reusing, ...)
1593 * where we cannot backup.
1595 nqindex = QUEUE_EMPTYKVA;
1596 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTYKVA]);
1600 * If no EMPTYKVA buffers and we are either
1601 * defragging or reusing, locate a CLEAN buffer
1602 * to free or reuse. If bufspace useage is low
1603 * skip this step so we can allocate a new buffer.
1605 if (defrag || bufspace >= lobufspace) {
1606 nqindex = QUEUE_CLEAN;
1607 nbp = TAILQ_FIRST(&bufqueues[QUEUE_CLEAN]);
1611 * If we could not find or were not allowed to reuse a
1612 * CLEAN buffer, check to see if it is ok to use an EMPTY
1613 * buffer. We can only use an EMPTY buffer if allocating
1614 * its KVA would not otherwise run us out of buffer space.
1616 if (nbp == NULL && defrag == 0 &&
1617 bufspace + maxsize < hibufspace) {
1618 nqindex = QUEUE_EMPTY;
1619 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTY]);
1624 * Run scan, possibly freeing data and/or kva mappings on the fly
1628 while ((bp = nbp) != NULL) {
1629 int qindex = nqindex;
1632 * Calculate next bp ( we can only use it if we do not block
1633 * or do other fancy things ).
1635 if ((nbp = TAILQ_NEXT(bp, b_freelist)) == NULL) {
1638 nqindex = QUEUE_EMPTYKVA;
1639 if ((nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTYKVA])))
1642 case QUEUE_EMPTYKVA:
1643 nqindex = QUEUE_CLEAN;
1644 if ((nbp = TAILQ_FIRST(&bufqueues[QUEUE_CLEAN])))
1658 KASSERT(bp->b_qindex == qindex, ("getnewbuf: inconsistant queue %d bp %p", qindex, bp));
1661 * Note: we no longer distinguish between VMIO and non-VMIO
1665 KASSERT((bp->b_flags & B_DELWRI) == 0, ("delwri buffer %p found in queue %d", bp, qindex));
1668 * If we are defragging then we need a buffer with
1669 * b_kvasize != 0. XXX this situation should no longer
1670 * occur, if defrag is non-zero the buffer's b_kvasize
1671 * should also be non-zero at this point. XXX
1673 if (defrag && bp->b_kvasize == 0) {
1674 printf("Warning: defrag empty buffer %p\n", bp);
1679 * Start freeing the bp. This is somewhat involved. nbp
1680 * remains valid only for QUEUE_EMPTY[KVA] bp's.
1683 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT) != 0)
1684 panic("getnewbuf: locked buf");
1687 if (qindex == QUEUE_CLEAN) {
1688 if (bp->b_flags & B_VMIO) {
1689 bp->b_flags &= ~B_ASYNC;
1690 vfs_vmio_release(bp);
1697 * NOTE: nbp is now entirely invalid. We can only restart
1698 * the scan from this point on.
1700 * Get the rest of the buffer freed up. b_kva* is still
1701 * valid after this operation.
1704 if (LIST_FIRST(&bp->b_dep) != NULL && bioops.io_deallocate)
1705 (*bioops.io_deallocate)(bp);
1706 if (bp->b_xflags & BX_BKGRDINPROG)
1707 panic("losing buffer 3");
1708 LIST_REMOVE(bp, b_hash);
1709 LIST_INSERT_HEAD(&invalhash, bp, b_hash);
1712 * spl protection not required when scrapping a buffer's
1713 * contents because it is already wired.
1722 bp->b_blkno = bp->b_lblkno = 0;
1723 bp->b_offset = NOOFFSET;
1728 bp->b_xio.xio_npages = 0;
1729 bp->b_dirtyoff = bp->b_dirtyend = 0;
1731 LIST_INIT(&bp->b_dep);
1734 * If we are defragging then free the buffer.
1737 bp->b_flags |= B_INVAL;
1745 * If we are overcomitted then recover the buffer and its
1746 * KVM space. This occurs in rare situations when multiple
1747 * processes are blocked in getnewbuf() or allocbuf().
1749 if (bufspace >= hibufspace)
1751 if (flushingbufs && bp->b_kvasize != 0) {
1752 bp->b_flags |= B_INVAL;
1757 if (bufspace < lobufspace)
1763 * If we exhausted our list, sleep as appropriate. We may have to
1764 * wakeup various daemons and write out some dirty buffers.
1766 * Generally we are sleeping due to insufficient buffer space.
1774 flags = VFS_BIO_NEED_BUFSPACE;
1776 } else if (bufspace >= hibufspace) {
1778 flags = VFS_BIO_NEED_BUFSPACE;
1781 flags = VFS_BIO_NEED_ANY;
1784 bd_speedup(); /* heeeelp */
1786 needsbuffer |= flags;
1787 while (needsbuffer & flags) {
1788 if (tsleep(&needsbuffer, slpflag, waitmsg, slptimeo))
1793 * We finally have a valid bp. We aren't quite out of the
1794 * woods, we still have to reserve kva space. In order
1795 * to keep fragmentation sane we only allocate kva in
1798 maxsize = (maxsize + BKVAMASK) & ~BKVAMASK;
1800 if (maxsize != bp->b_kvasize) {
1801 vm_offset_t addr = 0;
1806 count = vm_map_entry_reserve(MAP_RESERVE_COUNT);
1807 vm_map_lock(buffer_map);
1809 if (vm_map_findspace(buffer_map,
1810 vm_map_min(buffer_map), maxsize,
1813 * Uh oh. Buffer map is to fragmented. We
1814 * must defragment the map.
1816 vm_map_unlock(buffer_map);
1817 vm_map_entry_release(count);
1820 bp->b_flags |= B_INVAL;
1825 vm_map_insert(buffer_map, &count,
1827 addr, addr + maxsize,
1828 VM_PROT_ALL, VM_PROT_ALL, MAP_NOFAULT);
1830 bp->b_kvabase = (caddr_t) addr;
1831 bp->b_kvasize = maxsize;
1832 bufspace += bp->b_kvasize;
1835 vm_map_unlock(buffer_map);
1836 vm_map_entry_release(count);
1838 bp->b_data = bp->b_kvabase;
1846 * buffer flushing daemon. Buffers are normally flushed by the
1847 * update daemon but if it cannot keep up this process starts to
1848 * take the load in an attempt to prevent getnewbuf() from blocking.
1851 static struct thread *bufdaemonthread;
1853 static struct kproc_desc buf_kp = {
1858 SYSINIT(bufdaemon, SI_SUB_KTHREAD_BUF, SI_ORDER_FIRST, kproc_start, &buf_kp)
1866 * This process needs to be suspended prior to shutdown sync.
1868 EVENTHANDLER_REGISTER(shutdown_pre_sync, shutdown_kproc,
1869 bufdaemonthread, SHUTDOWN_PRI_LAST);
1872 * This process is allowed to take the buffer cache to the limit
1877 kproc_suspend_loop();
1880 * Do the flush. Limit the amount of in-transit I/O we
1881 * allow to build up, otherwise we would completely saturate
1882 * the I/O system. Wakeup any waiting processes before we
1883 * normally would so they can run in parallel with our drain.
1885 while (numdirtybuffers > lodirtybuffers) {
1886 if (flushbufqueues() == 0)
1888 waitrunningbufspace();
1889 numdirtywakeup((lodirtybuffers + hidirtybuffers) / 2);
1893 * Only clear bd_request if we have reached our low water
1894 * mark. The buf_daemon normally waits 5 seconds and
1895 * then incrementally flushes any dirty buffers that have
1896 * built up, within reason.
1898 * If we were unable to hit our low water mark and couldn't
1899 * find any flushable buffers, we sleep half a second.
1900 * Otherwise we loop immediately.
1902 if (numdirtybuffers <= lodirtybuffers) {
1904 * We reached our low water mark, reset the
1905 * request and sleep until we are needed again.
1906 * The sleep is just so the suspend code works.
1909 tsleep(&bd_request, 0, "psleep", hz);
1912 * We couldn't find any flushable dirty buffers but
1913 * still have too many dirty buffers, we
1914 * have to sleep and try again. (rare)
1916 tsleep(&bd_request, 0, "qsleep", hz / 2);
1924 * Try to flush a buffer in the dirty queue. We must be careful to
1925 * free up B_INVAL buffers instead of write them, which NFS is
1926 * particularly sensitive to.
1930 flushbufqueues(void)
1935 bp = TAILQ_FIRST(&bufqueues[QUEUE_DIRTY]);
1938 KASSERT((bp->b_flags & B_DELWRI), ("unexpected clean buffer %p", bp));
1939 if ((bp->b_flags & B_DELWRI) != 0 &&
1940 (bp->b_xflags & BX_BKGRDINPROG) == 0) {
1941 if (bp->b_flags & B_INVAL) {
1942 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT) != 0)
1943 panic("flushbufqueues: locked buf");
1949 if (LIST_FIRST(&bp->b_dep) != NULL &&
1950 bioops.io_countdeps &&
1951 (bp->b_flags & B_DEFERRED) == 0 &&
1952 (*bioops.io_countdeps)(bp, 0)) {
1953 TAILQ_REMOVE(&bufqueues[QUEUE_DIRTY],
1955 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_DIRTY],
1957 bp->b_flags |= B_DEFERRED;
1958 bp = TAILQ_FIRST(&bufqueues[QUEUE_DIRTY]);
1965 bp = TAILQ_NEXT(bp, b_freelist);
1971 * Check to see if a block is currently memory resident.
1974 incore(struct vnode * vp, daddr_t blkno)
1979 bp = gbincore(vp, blkno);
1985 * Returns true if no I/O is needed to access the associated VM object.
1986 * This is like incore except it also hunts around in the VM system for
1989 * Note that we ignore vm_page_free() races from interrupts against our
1990 * lookup, since if the caller is not protected our return value will not
1991 * be any more valid then otherwise once we splx().
1994 inmem(struct vnode * vp, daddr_t blkno)
1997 vm_offset_t toff, tinc, size;
2001 if (incore(vp, blkno))
2003 if (vp->v_mount == NULL)
2005 if (VOP_GETVOBJECT(vp, &obj) != 0 || (vp->v_flag & VOBJBUF) == 0)
2009 if (size > vp->v_mount->mnt_stat.f_iosize)
2010 size = vp->v_mount->mnt_stat.f_iosize;
2011 off = (vm_ooffset_t)blkno * (vm_ooffset_t)vp->v_mount->mnt_stat.f_iosize;
2013 for (toff = 0; toff < vp->v_mount->mnt_stat.f_iosize; toff += tinc) {
2014 m = vm_page_lookup(obj, OFF_TO_IDX(off + toff));
2018 if (tinc > PAGE_SIZE - ((toff + off) & PAGE_MASK))
2019 tinc = PAGE_SIZE - ((toff + off) & PAGE_MASK);
2020 if (vm_page_is_valid(m,
2021 (vm_offset_t) ((toff + off) & PAGE_MASK), tinc) == 0)
2030 * Sets the dirty range for a buffer based on the status of the dirty
2031 * bits in the pages comprising the buffer.
2033 * The range is limited to the size of the buffer.
2035 * This routine is primarily used by NFS, but is generalized for the
2039 vfs_setdirty(struct buf *bp)
2045 * Degenerate case - empty buffer
2048 if (bp->b_bufsize == 0)
2052 * We qualify the scan for modified pages on whether the
2053 * object has been flushed yet. The OBJ_WRITEABLE flag
2054 * is not cleared simply by protecting pages off.
2057 if ((bp->b_flags & B_VMIO) == 0)
2060 object = bp->b_xio.xio_pages[0]->object;
2062 if ((object->flags & OBJ_WRITEABLE) && !(object->flags & OBJ_MIGHTBEDIRTY))
2063 printf("Warning: object %p writeable but not mightbedirty\n", object);
2064 if (!(object->flags & OBJ_WRITEABLE) && (object->flags & OBJ_MIGHTBEDIRTY))
2065 printf("Warning: object %p mightbedirty but not writeable\n", object);
2067 if (object->flags & (OBJ_MIGHTBEDIRTY|OBJ_CLEANING)) {
2068 vm_offset_t boffset;
2069 vm_offset_t eoffset;
2072 * test the pages to see if they have been modified directly
2073 * by users through the VM system.
2075 for (i = 0; i < bp->b_xio.xio_npages; i++) {
2076 vm_page_flag_clear(bp->b_xio.xio_pages[i], PG_ZERO);
2077 vm_page_test_dirty(bp->b_xio.xio_pages[i]);
2081 * Calculate the encompassing dirty range, boffset and eoffset,
2082 * (eoffset - boffset) bytes.
2085 for (i = 0; i < bp->b_xio.xio_npages; i++) {
2086 if (bp->b_xio.xio_pages[i]->dirty)
2089 boffset = (i << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK);
2091 for (i = bp->b_xio.xio_npages - 1; i >= 0; --i) {
2092 if (bp->b_xio.xio_pages[i]->dirty) {
2096 eoffset = ((i + 1) << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK);
2099 * Fit it to the buffer.
2102 if (eoffset > bp->b_bcount)
2103 eoffset = bp->b_bcount;
2106 * If we have a good dirty range, merge with the existing
2110 if (boffset < eoffset) {
2111 if (bp->b_dirtyoff > boffset)
2112 bp->b_dirtyoff = boffset;
2113 if (bp->b_dirtyend < eoffset)
2114 bp->b_dirtyend = eoffset;
2122 * Get a block given a specified block and offset into a file/device.
2123 * The buffers B_DONE bit will be cleared on return, making it almost
2124 * ready for an I/O initiation. B_INVAL may or may not be set on
2125 * return. The caller should clear B_INVAL prior to initiating a
2128 * IT IS IMPORTANT TO UNDERSTAND THAT IF YOU CALL GETBLK() AND B_CACHE
2129 * IS NOT SET, YOU MUST INITIALIZE THE RETURNED BUFFER, ISSUE A READ,
2130 * OR SET B_INVAL BEFORE RETIRING IT. If you retire a getblk'd buffer
2131 * without doing any of those things the system will likely believe
2132 * the buffer to be valid (especially if it is not B_VMIO), and the
2133 * next getblk() will return the buffer with B_CACHE set.
2135 * For a non-VMIO buffer, B_CACHE is set to the opposite of B_INVAL for
2136 * an existing buffer.
2138 * For a VMIO buffer, B_CACHE is modified according to the backing VM.
2139 * If getblk()ing a previously 0-sized invalid buffer, B_CACHE is set
2140 * and then cleared based on the backing VM. If the previous buffer is
2141 * non-0-sized but invalid, B_CACHE will be cleared.
2143 * If getblk() must create a new buffer, the new buffer is returned with
2144 * both B_INVAL and B_CACHE clear unless it is a VMIO buffer, in which
2145 * case it is returned with B_INVAL clear and B_CACHE set based on the
2148 * getblk() also forces a VOP_BWRITE() for any B_DELWRI buffer whos
2149 * B_CACHE bit is clear.
2151 * What this means, basically, is that the caller should use B_CACHE to
2152 * determine whether the buffer is fully valid or not and should clear
2153 * B_INVAL prior to issuing a read. If the caller intends to validate
2154 * the buffer by loading its data area with something, the caller needs
2155 * to clear B_INVAL. If the caller does this without issuing an I/O,
2156 * the caller should set B_CACHE ( as an optimization ), else the caller
2157 * should issue the I/O and biodone() will set B_CACHE if the I/O was
2158 * a write attempt or if it was a successfull read. If the caller
2159 * intends to issue a READ, the caller must clear B_INVAL and B_ERROR
2160 * prior to issuing the READ. biodone() will *not* clear B_INVAL.
2163 getblk(struct vnode * vp, daddr_t blkno, int size, int slpflag, int slptimeo)
2167 struct bufhashhdr *bh;
2169 if (size > MAXBSIZE)
2170 panic("getblk: size(%d) > MAXBSIZE(%d)", size, MAXBSIZE);
2175 * Block if we are low on buffers. Certain processes are allowed
2176 * to completely exhaust the buffer cache.
2178 * If this check ever becomes a bottleneck it may be better to
2179 * move it into the else, when gbincore() fails. At the moment
2180 * it isn't a problem.
2182 * XXX remove, we cannot afford to block anywhere if holding a vnode
2183 * lock in low-memory situation, so take it to the max.
2185 if (numfreebuffers == 0) {
2188 needsbuffer |= VFS_BIO_NEED_ANY;
2189 tsleep(&needsbuffer, slpflag, "newbuf", slptimeo);
2192 if ((bp = gbincore(vp, blkno))) {
2194 * Buffer is in-core. If the buffer is not busy, it must
2198 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT)) {
2199 if (BUF_TIMELOCK(bp, LK_EXCLUSIVE | LK_SLEEPFAIL,
2200 "getblk", slpflag, slptimeo) == ENOLCK)
2203 return (struct buf *) NULL;
2207 * The buffer is locked. B_CACHE is cleared if the buffer is
2208 * invalid. Ohterwise, for a non-VMIO buffer, B_CACHE is set
2209 * and for a VMIO buffer B_CACHE is adjusted according to the
2212 if (bp->b_flags & B_INVAL)
2213 bp->b_flags &= ~B_CACHE;
2214 else if ((bp->b_flags & (B_VMIO | B_INVAL)) == 0)
2215 bp->b_flags |= B_CACHE;
2219 * check for size inconsistancies for non-VMIO case.
2222 if (bp->b_bcount != size) {
2223 if ((bp->b_flags & B_VMIO) == 0 ||
2224 (size > bp->b_kvasize)) {
2225 if (bp->b_flags & B_DELWRI) {
2226 bp->b_flags |= B_NOCACHE;
2227 VOP_BWRITE(bp->b_vp, bp);
2229 if ((bp->b_flags & B_VMIO) &&
2230 (LIST_FIRST(&bp->b_dep) == NULL)) {
2231 bp->b_flags |= B_RELBUF;
2234 bp->b_flags |= B_NOCACHE;
2235 VOP_BWRITE(bp->b_vp, bp);
2243 * If the size is inconsistant in the VMIO case, we can resize
2244 * the buffer. This might lead to B_CACHE getting set or
2245 * cleared. If the size has not changed, B_CACHE remains
2246 * unchanged from its previous state.
2249 if (bp->b_bcount != size)
2252 KASSERT(bp->b_offset != NOOFFSET,
2253 ("getblk: no buffer offset"));
2256 * A buffer with B_DELWRI set and B_CACHE clear must
2257 * be committed before we can return the buffer in
2258 * order to prevent the caller from issuing a read
2259 * ( due to B_CACHE not being set ) and overwriting
2262 * Most callers, including NFS and FFS, need this to
2263 * operate properly either because they assume they
2264 * can issue a read if B_CACHE is not set, or because
2265 * ( for example ) an uncached B_DELWRI might loop due
2266 * to softupdates re-dirtying the buffer. In the latter
2267 * case, B_CACHE is set after the first write completes,
2268 * preventing further loops.
2270 * NOTE! b*write() sets B_CACHE. If we cleared B_CACHE
2271 * above while extending the buffer, we cannot allow the
2272 * buffer to remain with B_CACHE set after the write
2273 * completes or it will represent a corrupt state. To
2274 * deal with this we set B_NOCACHE to scrap the buffer
2277 * We might be able to do something fancy, like setting
2278 * B_CACHE in bwrite() except if B_DELWRI is already set,
2279 * so the below call doesn't set B_CACHE, but that gets real
2280 * confusing. This is much easier.
2283 if ((bp->b_flags & (B_CACHE|B_DELWRI)) == B_DELWRI) {
2284 bp->b_flags |= B_NOCACHE;
2285 VOP_BWRITE(bp->b_vp, bp);
2290 bp->b_flags &= ~B_DONE;
2293 * Buffer is not in-core, create new buffer. The buffer
2294 * returned by getnewbuf() is locked. Note that the returned
2295 * buffer is also considered valid (not marked B_INVAL).
2297 int bsize, maxsize, vmio;
2300 if (vn_isdisk(vp, NULL))
2302 else if (vp->v_mountedhere)
2303 bsize = vp->v_mountedhere->mnt_stat.f_iosize;
2304 else if (vp->v_mount)
2305 bsize = vp->v_mount->mnt_stat.f_iosize;
2309 offset = (off_t)blkno * bsize;
2310 vmio = (VOP_GETVOBJECT(vp, NULL) == 0) && (vp->v_flag & VOBJBUF);
2311 maxsize = vmio ? size + (offset & PAGE_MASK) : size;
2312 maxsize = imax(maxsize, bsize);
2314 if ((bp = getnewbuf(slpflag, slptimeo, size, maxsize)) == NULL) {
2315 if (slpflag || slptimeo) {
2323 * This code is used to make sure that a buffer is not
2324 * created while the getnewbuf routine is blocked.
2325 * This can be a problem whether the vnode is locked or not.
2326 * If the buffer is created out from under us, we have to
2327 * throw away the one we just created. There is now window
2328 * race because we are safely running at splbio() from the
2329 * point of the duplicate buffer creation through to here,
2330 * and we've locked the buffer.
2332 if (gbincore(vp, blkno)) {
2333 bp->b_flags |= B_INVAL;
2339 * Insert the buffer into the hash, so that it can
2340 * be found by incore.
2342 bp->b_blkno = bp->b_lblkno = blkno;
2343 bp->b_offset = offset;
2346 LIST_REMOVE(bp, b_hash);
2347 bh = bufhash(vp, blkno);
2348 LIST_INSERT_HEAD(bh, bp, b_hash);
2351 * set B_VMIO bit. allocbuf() the buffer bigger. Since the
2352 * buffer size starts out as 0, B_CACHE will be set by
2353 * allocbuf() for the VMIO case prior to it testing the
2354 * backing store for validity.
2358 bp->b_flags |= B_VMIO;
2359 #if defined(VFS_BIO_DEBUG)
2360 if (vn_canvmio(vp) != TRUE)
2361 printf("getblk: vmioing file type %d???\n", vp->v_type);
2364 bp->b_flags &= ~B_VMIO;
2370 bp->b_flags &= ~B_DONE;
2376 * Get an empty, disassociated buffer of given size. The buffer is initially
2379 * spl protection is not required for the allocbuf() call because races are
2389 maxsize = (size + BKVAMASK) & ~BKVAMASK;
2392 while ((bp = getnewbuf(0, 0, size, maxsize)) == 0);
2395 bp->b_flags |= B_INVAL; /* b_dep cleared by getnewbuf() */
2401 * This code constitutes the buffer memory from either anonymous system
2402 * memory (in the case of non-VMIO operations) or from an associated
2403 * VM object (in the case of VMIO operations). This code is able to
2404 * resize a buffer up or down.
2406 * Note that this code is tricky, and has many complications to resolve
2407 * deadlock or inconsistant data situations. Tread lightly!!!
2408 * There are B_CACHE and B_DELWRI interactions that must be dealt with by
2409 * the caller. Calling this code willy nilly can result in the loss of data.
2411 * allocbuf() only adjusts B_CACHE for VMIO buffers. getblk() deals with
2412 * B_CACHE for the non-VMIO case.
2414 * This routine does not need to be called at splbio() but you must own the
2418 allocbuf(struct buf *bp, int size)
2420 int newbsize, mbsize;
2423 if (BUF_REFCNT(bp) == 0)
2424 panic("allocbuf: buffer not busy");
2426 if (bp->b_kvasize < size)
2427 panic("allocbuf: buffer too small");
2429 if ((bp->b_flags & B_VMIO) == 0) {
2433 * Just get anonymous memory from the kernel. Don't
2434 * mess with B_CACHE.
2436 mbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1);
2437 #if !defined(NO_B_MALLOC)
2438 if (bp->b_flags & B_MALLOC)
2442 newbsize = round_page(size);
2444 if (newbsize < bp->b_bufsize) {
2445 #if !defined(NO_B_MALLOC)
2447 * malloced buffers are not shrunk
2449 if (bp->b_flags & B_MALLOC) {
2451 bp->b_bcount = size;
2453 free(bp->b_data, M_BIOBUF);
2454 if (bp->b_bufsize) {
2455 bufmallocspace -= bp->b_bufsize;
2459 bp->b_data = bp->b_kvabase;
2461 bp->b_flags &= ~B_MALLOC;
2468 (vm_offset_t) bp->b_data + newbsize,
2469 (vm_offset_t) bp->b_data + bp->b_bufsize);
2470 } else if (newbsize > bp->b_bufsize) {
2471 #if !defined(NO_B_MALLOC)
2473 * We only use malloced memory on the first allocation.
2474 * and revert to page-allocated memory when the buffer
2477 if ( (bufmallocspace < maxbufmallocspace) &&
2478 (bp->b_bufsize == 0) &&
2479 (mbsize <= PAGE_SIZE/2)) {
2481 bp->b_data = malloc(mbsize, M_BIOBUF, M_WAITOK);
2482 bp->b_bufsize = mbsize;
2483 bp->b_bcount = size;
2484 bp->b_flags |= B_MALLOC;
2485 bufmallocspace += mbsize;
2491 #if !defined(NO_B_MALLOC)
2493 * If the buffer is growing on its other-than-first allocation,
2494 * then we revert to the page-allocation scheme.
2496 if (bp->b_flags & B_MALLOC) {
2497 origbuf = bp->b_data;
2498 origbufsize = bp->b_bufsize;
2499 bp->b_data = bp->b_kvabase;
2500 if (bp->b_bufsize) {
2501 bufmallocspace -= bp->b_bufsize;
2505 bp->b_flags &= ~B_MALLOC;
2506 newbsize = round_page(newbsize);
2511 (vm_offset_t) bp->b_data + bp->b_bufsize,
2512 (vm_offset_t) bp->b_data + newbsize);
2513 #if !defined(NO_B_MALLOC)
2515 bcopy(origbuf, bp->b_data, origbufsize);
2516 free(origbuf, M_BIOBUF);
2524 newbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1);
2525 desiredpages = (size == 0) ? 0 :
2526 num_pages((bp->b_offset & PAGE_MASK) + newbsize);
2528 #if !defined(NO_B_MALLOC)
2529 if (bp->b_flags & B_MALLOC)
2530 panic("allocbuf: VMIO buffer can't be malloced");
2533 * Set B_CACHE initially if buffer is 0 length or will become
2536 if (size == 0 || bp->b_bufsize == 0)
2537 bp->b_flags |= B_CACHE;
2539 if (newbsize < bp->b_bufsize) {
2541 * DEV_BSIZE aligned new buffer size is less then the
2542 * DEV_BSIZE aligned existing buffer size. Figure out
2543 * if we have to remove any pages.
2545 if (desiredpages < bp->b_xio.xio_npages) {
2546 for (i = desiredpages; i < bp->b_xio.xio_npages; i++) {
2548 * the page is not freed here -- it
2549 * is the responsibility of
2550 * vnode_pager_setsize
2552 m = bp->b_xio.xio_pages[i];
2553 KASSERT(m != bogus_page,
2554 ("allocbuf: bogus page found"));
2555 while (vm_page_sleep_busy(m, TRUE, "biodep"))
2558 bp->b_xio.xio_pages[i] = NULL;
2559 vm_page_unwire(m, 0);
2561 pmap_qremove((vm_offset_t) trunc_page((vm_offset_t)bp->b_data) +
2562 (desiredpages << PAGE_SHIFT), (bp->b_xio.xio_npages - desiredpages));
2563 bp->b_xio.xio_npages = desiredpages;
2565 } else if (size > bp->b_bcount) {
2567 * We are growing the buffer, possibly in a
2568 * byte-granular fashion.
2576 * Step 1, bring in the VM pages from the object,
2577 * allocating them if necessary. We must clear
2578 * B_CACHE if these pages are not valid for the
2579 * range covered by the buffer.
2581 * spl protection is required to protect against
2582 * interrupts unbusying and freeing pages between
2583 * our vm_page_lookup() and our busycheck/wiring
2587 VOP_GETVOBJECT(vp, &obj);
2590 while (bp->b_xio.xio_npages < desiredpages) {
2594 pi = OFF_TO_IDX(bp->b_offset) + bp->b_xio.xio_npages;
2595 if ((m = vm_page_lookup(obj, pi)) == NULL) {
2597 * note: must allocate system pages
2598 * since blocking here could intefere
2599 * with paging I/O, no matter which
2602 m = vm_page_alloc(obj, pi, VM_ALLOC_NORMAL | VM_ALLOC_SYSTEM);
2605 vm_pageout_deficit += desiredpages -
2606 bp->b_xio.xio_npages;
2610 bp->b_flags &= ~B_CACHE;
2611 bp->b_xio.xio_pages[bp->b_xio.xio_npages] = m;
2612 ++bp->b_xio.xio_npages;
2618 * We found a page. If we have to sleep on it,
2619 * retry because it might have gotten freed out
2622 * We can only test PG_BUSY here. Blocking on
2623 * m->busy might lead to a deadlock:
2625 * vm_fault->getpages->cluster_read->allocbuf
2629 if (vm_page_sleep_busy(m, FALSE, "pgtblk"))
2633 * We have a good page. Should we wakeup the
2636 if ((curthread != pagethread) &&
2637 ((m->queue - m->pc) == PQ_CACHE) &&
2638 ((vmstats.v_free_count + vmstats.v_cache_count) <
2639 (vmstats.v_free_min + vmstats.v_cache_min))) {
2640 pagedaemon_wakeup();
2642 vm_page_flag_clear(m, PG_ZERO);
2644 bp->b_xio.xio_pages[bp->b_xio.xio_npages] = m;
2645 ++bp->b_xio.xio_npages;
2650 * Step 2. We've loaded the pages into the buffer,
2651 * we have to figure out if we can still have B_CACHE
2652 * set. Note that B_CACHE is set according to the
2653 * byte-granular range ( bcount and size ), new the
2654 * aligned range ( newbsize ).
2656 * The VM test is against m->valid, which is DEV_BSIZE
2657 * aligned. Needless to say, the validity of the data
2658 * needs to also be DEV_BSIZE aligned. Note that this
2659 * fails with NFS if the server or some other client
2660 * extends the file's EOF. If our buffer is resized,
2661 * B_CACHE may remain set! XXX
2664 toff = bp->b_bcount;
2665 tinc = PAGE_SIZE - ((bp->b_offset + toff) & PAGE_MASK);
2667 while ((bp->b_flags & B_CACHE) && toff < size) {
2670 if (tinc > (size - toff))
2673 pi = ((bp->b_offset & PAGE_MASK) + toff) >>
2681 bp->b_xio.xio_pages[pi]
2688 * Step 3, fixup the KVM pmap. Remember that
2689 * bp->b_data is relative to bp->b_offset, but
2690 * bp->b_offset may be offset into the first page.
2693 bp->b_data = (caddr_t)
2694 trunc_page((vm_offset_t)bp->b_data);
2696 (vm_offset_t)bp->b_data,
2697 bp->b_xio.xio_pages,
2698 bp->b_xio.xio_npages
2700 bp->b_data = (caddr_t)((vm_offset_t)bp->b_data |
2701 (vm_offset_t)(bp->b_offset & PAGE_MASK));
2704 if (newbsize < bp->b_bufsize)
2706 bp->b_bufsize = newbsize; /* actual buffer allocation */
2707 bp->b_bcount = size; /* requested buffer size */
2714 * Wait for buffer I/O completion, returning error status. The buffer
2715 * is left locked and B_DONE on return. B_EINTR is converted into a EINTR
2716 * error and cleared.
2719 biowait(struct buf * bp)
2724 while ((bp->b_flags & B_DONE) == 0) {
2725 #if defined(NO_SCHEDULE_MODS)
2726 tsleep(bp, 0, "biowait", 0);
2728 if (bp->b_flags & B_READ)
2729 tsleep(bp, 0, "biord", 0);
2731 tsleep(bp, 0, "biowr", 0);
2735 if (bp->b_flags & B_EINTR) {
2736 bp->b_flags &= ~B_EINTR;
2739 if (bp->b_flags & B_ERROR) {
2740 return (bp->b_error ? bp->b_error : EIO);
2749 * Finish I/O on a buffer, optionally calling a completion function.
2750 * This is usually called from an interrupt so process blocking is
2753 * biodone is also responsible for setting B_CACHE in a B_VMIO bp.
2754 * In a non-VMIO bp, B_CACHE will be set on the next getblk()
2755 * assuming B_INVAL is clear.
2757 * For the VMIO case, we set B_CACHE if the op was a read and no
2758 * read error occured, or if the op was a write. B_CACHE is never
2759 * set if the buffer is invalid or otherwise uncacheable.
2761 * biodone does not mess with B_INVAL, allowing the I/O routine or the
2762 * initiator to leave B_INVAL set to brelse the buffer out of existance
2763 * in the biodone routine.
2765 * b_dev is required to be reinitialized prior to the top level strategy
2766 * call in a device stack. To avoid improper reuse, biodone() sets
2770 biodone(struct buf *bp)
2776 KASSERT(BUF_REFCNTNB(bp) > 0, ("biodone: bp %p not busy %d", bp, BUF_REFCNTNB(bp)));
2777 KASSERT(!(bp->b_flags & B_DONE), ("biodone: bp %p already done", bp));
2779 bp->b_flags |= B_DONE;
2781 runningbufwakeup(bp);
2783 if (bp->b_flags & B_FREEBUF) {
2789 if ((bp->b_flags & B_READ) == 0) {
2793 /* call optional completion function if requested */
2794 if (bp->b_flags & B_CALL) {
2795 bp->b_flags &= ~B_CALL;
2796 (*bp->b_iodone) (bp);
2800 if (LIST_FIRST(&bp->b_dep) != NULL && bioops.io_complete)
2801 (*bioops.io_complete)(bp);
2803 if (bp->b_flags & B_VMIO) {
2809 struct vnode *vp = bp->b_vp;
2811 error = VOP_GETVOBJECT(vp, &obj);
2813 #if defined(VFS_BIO_DEBUG)
2814 if (vp->v_holdcnt == 0) {
2815 panic("biodone: zero vnode hold count");
2819 panic("biodone: missing VM object");
2822 if ((vp->v_flag & VOBJBUF) == 0) {
2823 panic("biodone: vnode is not setup for merged cache");
2827 foff = bp->b_offset;
2828 KASSERT(bp->b_offset != NOOFFSET,
2829 ("biodone: no buffer offset"));
2832 panic("biodone: no object");
2834 #if defined(VFS_BIO_DEBUG)
2835 if (obj->paging_in_progress < bp->b_xio.xio_npages) {
2836 printf("biodone: paging in progress(%d) < bp->b_xio.xio_npages(%d)\n",
2837 obj->paging_in_progress, bp->b_xio.xio_npages);
2842 * Set B_CACHE if the op was a normal read and no error
2843 * occured. B_CACHE is set for writes in the b*write()
2846 iosize = bp->b_bcount - bp->b_resid;
2847 if ((bp->b_flags & (B_READ|B_FREEBUF|B_INVAL|B_NOCACHE|B_ERROR)) == B_READ) {
2848 bp->b_flags |= B_CACHE;
2851 for (i = 0; i < bp->b_xio.xio_npages; i++) {
2855 resid = ((foff + PAGE_SIZE) & ~(off_t)PAGE_MASK) - foff;
2860 * cleanup bogus pages, restoring the originals. Since
2861 * the originals should still be wired, we don't have
2862 * to worry about interrupt/freeing races destroying
2863 * the VM object association.
2865 m = bp->b_xio.xio_pages[i];
2866 if (m == bogus_page) {
2868 m = vm_page_lookup(obj, OFF_TO_IDX(foff));
2870 panic("biodone: page disappeared");
2871 bp->b_xio.xio_pages[i] = m;
2872 pmap_qenter(trunc_page((vm_offset_t)bp->b_data),
2873 bp->b_xio.xio_pages, bp->b_xio.xio_npages);
2875 #if defined(VFS_BIO_DEBUG)
2876 if (OFF_TO_IDX(foff) != m->pindex) {
2878 "biodone: foff(%lu)/m->pindex(%d) mismatch\n",
2879 (unsigned long)foff, m->pindex);
2884 * In the write case, the valid and clean bits are
2885 * already changed correctly ( see bdwrite() ), so we
2886 * only need to do this here in the read case.
2888 if ((bp->b_flags & B_READ) && !bogusflag && resid > 0) {
2889 vfs_page_set_valid(bp, foff, i, m);
2891 vm_page_flag_clear(m, PG_ZERO);
2894 * when debugging new filesystems or buffer I/O methods, this
2895 * is the most common error that pops up. if you see this, you
2896 * have not set the page busy flag correctly!!!
2899 printf("biodone: page busy < 0, "
2900 "pindex: %d, foff: 0x(%x,%x), "
2901 "resid: %d, index: %d\n",
2902 (int) m->pindex, (int)(foff >> 32),
2903 (int) foff & 0xffffffff, resid, i);
2904 if (!vn_isdisk(vp, NULL))
2905 printf(" iosize: %ld, lblkno: %d, flags: 0x%lx, npages: %d\n",
2906 bp->b_vp->v_mount->mnt_stat.f_iosize,
2908 bp->b_flags, bp->b_xio.xio_npages);
2910 printf(" VDEV, lblkno: %d, flags: 0x%lx, npages: %d\n",
2912 bp->b_flags, bp->b_xio.xio_npages);
2913 printf(" valid: 0x%x, dirty: 0x%x, wired: %d\n",
2914 m->valid, m->dirty, m->wire_count);
2915 panic("biodone: page busy < 0");
2917 vm_page_io_finish(m);
2918 vm_object_pip_subtract(obj, 1);
2919 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK;
2923 vm_object_pip_wakeupn(obj, 0);
2927 * For asynchronous completions, release the buffer now. The brelse
2928 * will do a wakeup there if necessary - so no need to do a wakeup
2929 * here in the async case. The sync case always needs to do a wakeup.
2932 if (bp->b_flags & B_ASYNC) {
2933 if ((bp->b_flags & (B_NOCACHE | B_INVAL | B_ERROR | B_RELBUF)) != 0)
2944 * This routine is called in lieu of iodone in the case of
2945 * incomplete I/O. This keeps the busy status for pages
2949 vfs_unbusy_pages(struct buf *bp)
2953 runningbufwakeup(bp);
2954 if (bp->b_flags & B_VMIO) {
2955 struct vnode *vp = bp->b_vp;
2958 VOP_GETVOBJECT(vp, &obj);
2960 for (i = 0; i < bp->b_xio.xio_npages; i++) {
2961 vm_page_t m = bp->b_xio.xio_pages[i];
2964 * When restoring bogus changes the original pages
2965 * should still be wired, so we are in no danger of
2966 * losing the object association and do not need
2967 * spl protection particularly.
2969 if (m == bogus_page) {
2970 m = vm_page_lookup(obj, OFF_TO_IDX(bp->b_offset) + i);
2972 panic("vfs_unbusy_pages: page missing");
2974 bp->b_xio.xio_pages[i] = m;
2975 pmap_qenter(trunc_page((vm_offset_t)bp->b_data),
2976 bp->b_xio.xio_pages, bp->b_xio.xio_npages);
2978 vm_object_pip_subtract(obj, 1);
2979 vm_page_flag_clear(m, PG_ZERO);
2980 vm_page_io_finish(m);
2982 vm_object_pip_wakeupn(obj, 0);
2987 * vfs_page_set_valid:
2989 * Set the valid bits in a page based on the supplied offset. The
2990 * range is restricted to the buffer's size.
2992 * This routine is typically called after a read completes.
2995 vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, int pageno, vm_page_t m)
2997 vm_ooffset_t soff, eoff;
3000 * Start and end offsets in buffer. eoff - soff may not cross a
3001 * page boundry or cross the end of the buffer. The end of the
3002 * buffer, in this case, is our file EOF, not the allocation size
3006 eoff = (off + PAGE_SIZE) & ~(off_t)PAGE_MASK;
3007 if (eoff > bp->b_offset + bp->b_bcount)
3008 eoff = bp->b_offset + bp->b_bcount;
3011 * Set valid range. This is typically the entire buffer and thus the
3015 vm_page_set_validclean(
3017 (vm_offset_t) (soff & PAGE_MASK),
3018 (vm_offset_t) (eoff - soff)
3024 * This routine is called before a device strategy routine.
3025 * It is used to tell the VM system that paging I/O is in
3026 * progress, and treat the pages associated with the buffer
3027 * almost as being PG_BUSY. Also the object paging_in_progress
3028 * flag is handled to make sure that the object doesn't become
3031 * Since I/O has not been initiated yet, certain buffer flags
3032 * such as B_ERROR or B_INVAL may be in an inconsistant state
3033 * and should be ignored.
3036 vfs_busy_pages(struct buf *bp, int clear_modify)
3040 if (bp->b_flags & B_VMIO) {
3041 struct vnode *vp = bp->b_vp;
3045 VOP_GETVOBJECT(vp, &obj);
3046 foff = bp->b_offset;
3047 KASSERT(bp->b_offset != NOOFFSET,
3048 ("vfs_busy_pages: no buffer offset"));
3052 for (i = 0; i < bp->b_xio.xio_npages; i++) {
3053 vm_page_t m = bp->b_xio.xio_pages[i];
3054 if (vm_page_sleep_busy(m, FALSE, "vbpage"))
3059 for (i = 0; i < bp->b_xio.xio_npages; i++) {
3060 vm_page_t m = bp->b_xio.xio_pages[i];
3062 vm_page_flag_clear(m, PG_ZERO);
3063 if ((bp->b_flags & B_CLUSTER) == 0) {
3064 vm_object_pip_add(obj, 1);
3065 vm_page_io_start(m);
3069 * When readying a buffer for a read ( i.e
3070 * clear_modify == 0 ), it is important to do
3071 * bogus_page replacement for valid pages in
3072 * partially instantiated buffers. Partially
3073 * instantiated buffers can, in turn, occur when
3074 * reconstituting a buffer from its VM backing store
3075 * base. We only have to do this if B_CACHE is
3076 * clear ( which causes the I/O to occur in the
3077 * first place ). The replacement prevents the read
3078 * I/O from overwriting potentially dirty VM-backed
3079 * pages. XXX bogus page replacement is, uh, bogus.
3080 * It may not work properly with small-block devices.
3081 * We need to find a better way.
3084 vm_page_protect(m, VM_PROT_NONE);
3086 vfs_page_set_valid(bp, foff, i, m);
3087 else if (m->valid == VM_PAGE_BITS_ALL &&
3088 (bp->b_flags & B_CACHE) == 0) {
3089 bp->b_xio.xio_pages[i] = bogus_page;
3092 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK;
3095 pmap_qenter(trunc_page((vm_offset_t)bp->b_data),
3096 bp->b_xio.xio_pages, bp->b_xio.xio_npages);
3100 * This is the easiest place to put the process accounting for the I/O
3106 if ((p = curthread->td_proc) != NULL) {
3107 if (bp->b_flags & B_READ)
3108 p->p_stats->p_ru.ru_inblock++;
3110 p->p_stats->p_ru.ru_oublock++;
3116 * Tell the VM system that the pages associated with this buffer
3117 * are clean. This is used for delayed writes where the data is
3118 * going to go to disk eventually without additional VM intevention.
3120 * Note that while we only really need to clean through to b_bcount, we
3121 * just go ahead and clean through to b_bufsize.
3124 vfs_clean_pages(struct buf *bp)
3128 if (bp->b_flags & B_VMIO) {
3131 foff = bp->b_offset;
3132 KASSERT(bp->b_offset != NOOFFSET,
3133 ("vfs_clean_pages: no buffer offset"));
3134 for (i = 0; i < bp->b_xio.xio_npages; i++) {
3135 vm_page_t m = bp->b_xio.xio_pages[i];
3136 vm_ooffset_t noff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK;
3137 vm_ooffset_t eoff = noff;
3139 if (eoff > bp->b_offset + bp->b_bufsize)
3140 eoff = bp->b_offset + bp->b_bufsize;
3141 vfs_page_set_valid(bp, foff, i, m);
3142 /* vm_page_clear_dirty(m, foff & PAGE_MASK, eoff - foff); */
3149 * vfs_bio_set_validclean:
3151 * Set the range within the buffer to valid and clean. The range is
3152 * relative to the beginning of the buffer, b_offset. Note that b_offset
3153 * itself may be offset from the beginning of the first page.
3157 vfs_bio_set_validclean(struct buf *bp, int base, int size)
3159 if (bp->b_flags & B_VMIO) {
3164 * Fixup base to be relative to beginning of first page.
3165 * Set initial n to be the maximum number of bytes in the
3166 * first page that can be validated.
3169 base += (bp->b_offset & PAGE_MASK);
3170 n = PAGE_SIZE - (base & PAGE_MASK);
3172 for (i = base / PAGE_SIZE; size > 0 && i < bp->b_xio.xio_npages; ++i) {
3173 vm_page_t m = bp->b_xio.xio_pages[i];
3178 vm_page_set_validclean(m, base & PAGE_MASK, n);
3189 * clear a buffer. This routine essentially fakes an I/O, so we need
3190 * to clear B_ERROR and B_INVAL.
3192 * Note that while we only theoretically need to clear through b_bcount,
3193 * we go ahead and clear through b_bufsize.
3197 vfs_bio_clrbuf(struct buf *bp)
3201 if ((bp->b_flags & (B_VMIO | B_MALLOC)) == B_VMIO) {
3202 bp->b_flags &= ~(B_INVAL|B_ERROR);
3203 if ((bp->b_xio.xio_npages == 1) && (bp->b_bufsize < PAGE_SIZE) &&
3204 (bp->b_offset & PAGE_MASK) == 0) {
3205 mask = (1 << (bp->b_bufsize / DEV_BSIZE)) - 1;
3206 if ((bp->b_xio.xio_pages[0]->valid & mask) == mask) {
3210 if (((bp->b_xio.xio_pages[0]->flags & PG_ZERO) == 0) &&
3211 ((bp->b_xio.xio_pages[0]->valid & mask) == 0)) {
3212 bzero(bp->b_data, bp->b_bufsize);
3213 bp->b_xio.xio_pages[0]->valid |= mask;
3218 ea = sa = bp->b_data;
3219 for(i=0;i<bp->b_xio.xio_npages;i++,sa=ea) {
3220 int j = ((vm_offset_t)sa & PAGE_MASK) / DEV_BSIZE;
3221 ea = (caddr_t)trunc_page((vm_offset_t)sa + PAGE_SIZE);
3222 ea = (caddr_t)(vm_offset_t)ulmin(
3223 (u_long)(vm_offset_t)ea,
3224 (u_long)(vm_offset_t)bp->b_data + bp->b_bufsize);
3225 mask = ((1 << ((ea - sa) / DEV_BSIZE)) - 1) << j;
3226 if ((bp->b_xio.xio_pages[i]->valid & mask) == mask)
3228 if ((bp->b_xio.xio_pages[i]->valid & mask) == 0) {
3229 if ((bp->b_xio.xio_pages[i]->flags & PG_ZERO) == 0) {
3233 for (; sa < ea; sa += DEV_BSIZE, j++) {
3234 if (((bp->b_xio.xio_pages[i]->flags & PG_ZERO) == 0) &&
3235 (bp->b_xio.xio_pages[i]->valid & (1<<j)) == 0)
3236 bzero(sa, DEV_BSIZE);
3239 bp->b_xio.xio_pages[i]->valid |= mask;
3240 vm_page_flag_clear(bp->b_xio.xio_pages[i], PG_ZERO);
3249 * vm_hold_load_pages and vm_hold_unload pages get pages into
3250 * a buffers address space. The pages are anonymous and are
3251 * not associated with a file object.
3254 vm_hold_load_pages(struct buf *bp, vm_offset_t from, vm_offset_t to)
3260 to = round_page(to);
3261 from = round_page(from);
3262 index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT;
3264 for (pg = from; pg < to; pg += PAGE_SIZE, index++) {
3269 * note: must allocate system pages since blocking here
3270 * could intefere with paging I/O, no matter which
3273 p = vm_page_alloc(kernel_object,
3274 ((pg - VM_MIN_KERNEL_ADDRESS) >> PAGE_SHIFT),
3275 VM_ALLOC_NORMAL | VM_ALLOC_SYSTEM);
3277 vm_pageout_deficit += (to - from) >> PAGE_SHIFT;
3282 p->valid = VM_PAGE_BITS_ALL;
3283 vm_page_flag_clear(p, PG_ZERO);
3284 pmap_kenter(pg, VM_PAGE_TO_PHYS(p));
3285 bp->b_xio.xio_pages[index] = p;
3288 bp->b_xio.xio_npages = index;
3292 vm_hold_free_pages(struct buf *bp, vm_offset_t from, vm_offset_t to)
3296 int index, newnpages;
3298 from = round_page(from);
3299 to = round_page(to);
3300 newnpages = index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT;
3302 for (pg = from; pg < to; pg += PAGE_SIZE, index++) {
3303 p = bp->b_xio.xio_pages[index];
3304 if (p && (index < bp->b_xio.xio_npages)) {
3306 printf("vm_hold_free_pages: blkno: %d, lblkno: %d\n",
3307 bp->b_blkno, bp->b_lblkno);
3309 bp->b_xio.xio_pages[index] = NULL;
3312 vm_page_unwire(p, 0);
3316 bp->b_xio.xio_npages = newnpages;
3320 * Map an IO request into kernel virtual address space.
3322 * All requests are (re)mapped into kernel VA space.
3323 * Notice that we use b_bufsize for the size of the buffer
3324 * to be mapped. b_bcount might be modified by the driver.
3327 vmapbuf(struct buf *bp)
3329 caddr_t addr, v, kva;
3335 if ((bp->b_flags & B_PHYS) == 0)
3337 if (bp->b_bufsize < 0)
3339 for (v = bp->b_saveaddr,
3340 addr = (caddr_t)trunc_page((vm_offset_t)bp->b_data),
3342 addr < bp->b_data + bp->b_bufsize;
3343 addr += PAGE_SIZE, v += PAGE_SIZE, pidx++) {
3345 * Do the vm_fault if needed; do the copy-on-write thing
3346 * when reading stuff off device into memory.
3349 i = vm_fault_quick((addr >= bp->b_data) ? addr : bp->b_data,
3350 (bp->b_flags&B_READ)?(VM_PROT_READ|VM_PROT_WRITE):VM_PROT_READ);
3352 for (i = 0; i < pidx; ++i) {
3353 vm_page_unhold(bp->b_xio.xio_pages[i]);
3354 bp->b_xio.xio_pages[i] = NULL;
3360 * WARNING! If sparc support is MFCd in the future this will
3361 * have to be changed from pmap_kextract() to pmap_extract()
3365 #error "If MFCing sparc support use pmap_extract"
3367 pa = pmap_kextract((vm_offset_t)addr);
3369 printf("vmapbuf: warning, race against user address during I/O");
3372 m = PHYS_TO_VM_PAGE(pa);
3374 bp->b_xio.xio_pages[pidx] = m;
3376 if (pidx > btoc(MAXPHYS))
3377 panic("vmapbuf: mapped more than MAXPHYS");
3378 pmap_qenter((vm_offset_t)bp->b_saveaddr, bp->b_xio.xio_pages, pidx);
3380 kva = bp->b_saveaddr;
3381 bp->b_xio.xio_npages = pidx;
3382 bp->b_saveaddr = bp->b_data;
3383 bp->b_data = kva + (((vm_offset_t) bp->b_data) & PAGE_MASK);
3388 * Free the io map PTEs associated with this IO operation.
3389 * We also invalidate the TLB entries and restore the original b_addr.
3392 vunmapbuf(struct buf *bp)
3398 if ((bp->b_flags & B_PHYS) == 0)
3401 npages = bp->b_xio.xio_npages;
3402 pmap_qremove(trunc_page((vm_offset_t)bp->b_data),
3404 m = bp->b_xio.xio_pages;
3405 for (pidx = 0; pidx < npages; pidx++)
3406 vm_page_unhold(*m++);
3408 bp->b_data = bp->b_saveaddr;
3411 #include "opt_ddb.h"
3413 #include <ddb/ddb.h>
3415 DB_SHOW_COMMAND(buffer, db_show_buffer)
3418 struct buf *bp = (struct buf *)addr;
3421 db_printf("usage: show buffer <addr>\n");
3425 db_printf("b_flags = 0x%b\n", (u_int)bp->b_flags, PRINT_BUF_FLAGS);
3426 db_printf("b_error = %d, b_bufsize = %ld, b_bcount = %ld, "
3427 "b_resid = %ld\nb_dev = (%d,%d), b_data = %p, "
3428 "b_blkno = %d, b_pblkno = %d\n",
3429 bp->b_error, bp->b_bufsize, bp->b_bcount, bp->b_resid,
3430 major(bp->b_dev), minor(bp->b_dev),
3431 bp->b_data, bp->b_blkno, bp->b_pblkno);
3432 if (bp->b_xio.xio_npages) {
3434 db_printf("b_xio.xio_npages = %d, pages(OBJ, IDX, PA): ",
3435 bp->b_xio.xio_npages);
3436 for (i = 0; i < bp->b_xio.xio_npages; i++) {
3438 m = bp->b_xio.xio_pages[i];
3439 db_printf("(%p, 0x%lx, 0x%lx)", (void *)m->object,
3440 (u_long)m->pindex, (u_long)VM_PAGE_TO_PHYS(m));
3441 if ((i + 1) < bp->b_xio.xio_npages)