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 1.115 2008/08/13 11:02:31 swildner 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/devicestat.h>
36 #include <sys/eventhandler.h>
38 #include <sys/malloc.h>
39 #include <sys/mount.h>
40 #include <sys/kernel.h>
41 #include <sys/kthread.h>
43 #include <sys/reboot.h>
44 #include <sys/resourcevar.h>
45 #include <sys/sysctl.h>
46 #include <sys/vmmeter.h>
47 #include <sys/vnode.h>
48 #include <sys/dsched.h>
51 #include <vm/vm_param.h>
52 #include <vm/vm_kern.h>
53 #include <vm/vm_pageout.h>
54 #include <vm/vm_page.h>
55 #include <vm/vm_object.h>
56 #include <vm/vm_extern.h>
57 #include <vm/vm_map.h>
58 #include <vm/vm_pager.h>
59 #include <vm/swap_pager.h>
62 #include <sys/thread2.h>
63 #include <sys/spinlock2.h>
64 #include <sys/mplock2.h>
65 #include <vm/vm_page2.h>
76 BQUEUE_NONE, /* not on any queue */
77 BQUEUE_LOCKED, /* locked buffers */
78 BQUEUE_CLEAN, /* non-B_DELWRI buffers */
79 BQUEUE_DIRTY, /* B_DELWRI buffers */
80 BQUEUE_DIRTY_HW, /* B_DELWRI buffers - heavy weight */
81 BQUEUE_EMPTYKVA, /* empty buffer headers with KVA assignment */
82 BQUEUE_EMPTY, /* empty buffer headers */
84 BUFFER_QUEUES /* number of buffer queues */
87 typedef enum bufq_type bufq_type_t;
89 #define BD_WAKE_SIZE 16384
90 #define BD_WAKE_MASK (BD_WAKE_SIZE - 1)
92 TAILQ_HEAD(bqueues, buf) bufqueues[BUFFER_QUEUES];
93 static struct spinlock bufqspin = SPINLOCK_INITIALIZER(&bufqspin);
94 static struct spinlock bufcspin = SPINLOCK_INITIALIZER(&bufcspin);
96 static MALLOC_DEFINE(M_BIOBUF, "BIO buffer", "BIO buffer");
98 struct buf *buf; /* buffer header pool */
100 static void vfs_clean_pages(struct buf *bp);
101 static void vfs_clean_one_page(struct buf *bp, int pageno, vm_page_t m);
102 static void vfs_dirty_one_page(struct buf *bp, int pageno, vm_page_t m);
103 static void vfs_vmio_release(struct buf *bp);
104 static int flushbufqueues(bufq_type_t q);
105 static vm_page_t bio_page_alloc(vm_object_t obj, vm_pindex_t pg, int deficit);
107 static void bd_signal(int totalspace);
108 static void buf_daemon(void);
109 static void buf_daemon_hw(void);
112 * bogus page -- for I/O to/from partially complete buffers
113 * this is a temporary solution to the problem, but it is not
114 * really that bad. it would be better to split the buffer
115 * for input in the case of buffers partially already in memory,
116 * but the code is intricate enough already.
118 vm_page_t bogus_page;
121 * These are all static, but make the ones we export globals so we do
122 * not need to use compiler magic.
124 int bufspace; /* locked by buffer_map */
126 static int bufmallocspace; /* atomic ops */
127 int maxbufmallocspace, lobufspace, hibufspace;
128 static int bufreusecnt, bufdefragcnt, buffreekvacnt;
129 static int lorunningspace;
130 static int hirunningspace;
131 static int runningbufreq; /* locked by bufcspin */
132 static int dirtybufspace; /* locked by bufcspin */
133 static int dirtybufcount; /* locked by bufcspin */
134 static int dirtybufspacehw; /* locked by bufcspin */
135 static int dirtybufcounthw; /* locked by bufcspin */
136 static int runningbufspace; /* locked by bufcspin */
137 static int runningbufcount; /* locked by bufcspin */
140 static int getnewbufcalls;
141 static int getnewbufrestarts;
142 static int recoverbufcalls;
143 static int needsbuffer; /* locked by bufcspin */
144 static int bd_request; /* locked by bufcspin */
145 static int bd_request_hw; /* locked by bufcspin */
146 static u_int bd_wake_ary[BD_WAKE_SIZE];
147 static u_int bd_wake_index;
148 static u_int vm_cycle_point = 40; /* 23-36 will migrate more act->inact */
149 static int debug_commit;
151 static struct thread *bufdaemon_td;
152 static struct thread *bufdaemonhw_td;
153 static u_int lowmempgallocs;
154 static u_int lowmempgfails;
157 * Sysctls for operational control of the buffer cache.
159 SYSCTL_INT(_vfs, OID_AUTO, lodirtybufspace, CTLFLAG_RW, &lodirtybufspace, 0,
160 "Number of dirty buffers to flush before bufdaemon becomes inactive");
161 SYSCTL_INT(_vfs, OID_AUTO, hidirtybufspace, CTLFLAG_RW, &hidirtybufspace, 0,
162 "High watermark used to trigger explicit flushing of dirty buffers");
163 SYSCTL_INT(_vfs, OID_AUTO, lorunningspace, CTLFLAG_RW, &lorunningspace, 0,
164 "Minimum amount of buffer space required for active I/O");
165 SYSCTL_INT(_vfs, OID_AUTO, hirunningspace, CTLFLAG_RW, &hirunningspace, 0,
166 "Maximum amount of buffer space to usable for active I/O");
167 SYSCTL_UINT(_vfs, OID_AUTO, lowmempgallocs, CTLFLAG_RW, &lowmempgallocs, 0,
168 "Page allocations done during periods of very low free memory");
169 SYSCTL_UINT(_vfs, OID_AUTO, lowmempgfails, CTLFLAG_RW, &lowmempgfails, 0,
170 "Page allocations which failed during periods of very low free memory");
171 SYSCTL_UINT(_vfs, OID_AUTO, vm_cycle_point, CTLFLAG_RW, &vm_cycle_point, 0,
172 "Recycle pages to active or inactive queue transition pt 0-64");
174 * Sysctls determining current state of the buffer cache.
176 SYSCTL_INT(_vfs, OID_AUTO, nbuf, CTLFLAG_RD, &nbuf, 0,
177 "Total number of buffers in buffer cache");
178 SYSCTL_INT(_vfs, OID_AUTO, dirtybufspace, CTLFLAG_RD, &dirtybufspace, 0,
179 "Pending bytes of dirty buffers (all)");
180 SYSCTL_INT(_vfs, OID_AUTO, dirtybufspacehw, CTLFLAG_RD, &dirtybufspacehw, 0,
181 "Pending bytes of dirty buffers (heavy weight)");
182 SYSCTL_INT(_vfs, OID_AUTO, dirtybufcount, CTLFLAG_RD, &dirtybufcount, 0,
183 "Pending number of dirty buffers");
184 SYSCTL_INT(_vfs, OID_AUTO, dirtybufcounthw, CTLFLAG_RD, &dirtybufcounthw, 0,
185 "Pending number of dirty buffers (heavy weight)");
186 SYSCTL_INT(_vfs, OID_AUTO, runningbufspace, CTLFLAG_RD, &runningbufspace, 0,
187 "I/O bytes currently in progress due to asynchronous writes");
188 SYSCTL_INT(_vfs, OID_AUTO, runningbufcount, CTLFLAG_RD, &runningbufcount, 0,
189 "I/O buffers currently in progress due to asynchronous writes");
190 SYSCTL_INT(_vfs, OID_AUTO, maxbufspace, CTLFLAG_RD, &maxbufspace, 0,
191 "Hard limit on maximum amount of memory usable for buffer space");
192 SYSCTL_INT(_vfs, OID_AUTO, hibufspace, CTLFLAG_RD, &hibufspace, 0,
193 "Soft limit on maximum amount of memory usable for buffer space");
194 SYSCTL_INT(_vfs, OID_AUTO, lobufspace, CTLFLAG_RD, &lobufspace, 0,
195 "Minimum amount of memory to reserve for system buffer space");
196 SYSCTL_INT(_vfs, OID_AUTO, bufspace, CTLFLAG_RD, &bufspace, 0,
197 "Amount of memory available for buffers");
198 SYSCTL_INT(_vfs, OID_AUTO, maxmallocbufspace, CTLFLAG_RD, &maxbufmallocspace,
199 0, "Maximum amount of memory reserved for buffers using malloc");
200 SYSCTL_INT(_vfs, OID_AUTO, bufmallocspace, CTLFLAG_RD, &bufmallocspace, 0,
201 "Amount of memory left for buffers using malloc-scheme");
202 SYSCTL_INT(_vfs, OID_AUTO, getnewbufcalls, CTLFLAG_RD, &getnewbufcalls, 0,
203 "New buffer header acquisition requests");
204 SYSCTL_INT(_vfs, OID_AUTO, getnewbufrestarts, CTLFLAG_RD, &getnewbufrestarts,
205 0, "New buffer header acquisition restarts");
206 SYSCTL_INT(_vfs, OID_AUTO, recoverbufcalls, CTLFLAG_RD, &recoverbufcalls, 0,
207 "Recover VM space in an emergency");
208 SYSCTL_INT(_vfs, OID_AUTO, bufdefragcnt, CTLFLAG_RD, &bufdefragcnt, 0,
209 "Buffer acquisition restarts due to fragmented buffer map");
210 SYSCTL_INT(_vfs, OID_AUTO, buffreekvacnt, CTLFLAG_RD, &buffreekvacnt, 0,
211 "Amount of time KVA space was deallocated in an arbitrary buffer");
212 SYSCTL_INT(_vfs, OID_AUTO, bufreusecnt, CTLFLAG_RD, &bufreusecnt, 0,
213 "Amount of time buffer re-use operations were successful");
214 SYSCTL_INT(_vfs, OID_AUTO, debug_commit, CTLFLAG_RW, &debug_commit, 0, "");
215 SYSCTL_INT(_debug_sizeof, OID_AUTO, buf, CTLFLAG_RD, 0, sizeof(struct buf),
216 "sizeof(struct buf)");
218 char *buf_wmesg = BUF_WMESG;
220 #define VFS_BIO_NEED_ANY 0x01 /* any freeable buffer */
221 #define VFS_BIO_NEED_UNUSED02 0x02
222 #define VFS_BIO_NEED_UNUSED04 0x04
223 #define VFS_BIO_NEED_BUFSPACE 0x08 /* wait for buf space, lo hysteresis */
228 * Called when buffer space is potentially available for recovery.
229 * getnewbuf() will block on this flag when it is unable to free
230 * sufficient buffer space. Buffer space becomes recoverable when
231 * bp's get placed back in the queues.
237 * If someone is waiting for BUF space, wake them up. Even
238 * though we haven't freed the kva space yet, the waiting
239 * process will be able to now.
241 spin_lock(&bufcspin);
242 if (needsbuffer & VFS_BIO_NEED_BUFSPACE) {
243 needsbuffer &= ~VFS_BIO_NEED_BUFSPACE;
244 spin_unlock(&bufcspin);
245 wakeup(&needsbuffer);
247 spin_unlock(&bufcspin);
254 * Accounting for I/O in progress.
258 runningbufwakeup(struct buf *bp)
263 if ((totalspace = bp->b_runningbufspace) != 0) {
264 spin_lock(&bufcspin);
265 runningbufspace -= totalspace;
267 bp->b_runningbufspace = 0;
270 * see waitrunningbufspace() for limit test.
272 limit = hirunningspace * 4 / 6;
273 if (runningbufreq && runningbufspace <= limit) {
275 spin_unlock(&bufcspin);
276 wakeup(&runningbufreq);
278 spin_unlock(&bufcspin);
280 bd_signal(totalspace);
287 * Called when a buffer has been added to one of the free queues to
288 * account for the buffer and to wakeup anyone waiting for free buffers.
289 * This typically occurs when large amounts of metadata are being handled
290 * by the buffer cache ( else buffer space runs out first, usually ).
297 spin_lock(&bufcspin);
299 needsbuffer &= ~VFS_BIO_NEED_ANY;
300 spin_unlock(&bufcspin);
301 wakeup(&needsbuffer);
303 spin_unlock(&bufcspin);
308 * waitrunningbufspace()
310 * Wait for the amount of running I/O to drop to hirunningspace * 4 / 6.
311 * This is the point where write bursting stops so we don't want to wait
312 * for the running amount to drop below it (at least if we still want bioq
315 * The caller may be using this function to block in a tight loop, we
316 * must block while runningbufspace is greater then or equal to
317 * hirunningspace * 4 / 6.
319 * And even with that it may not be enough, due to the presence of
320 * B_LOCKED dirty buffers, so also wait for at least one running buffer
324 waitrunningbufspace(void)
326 int limit = hirunningspace * 4 / 6;
329 spin_lock(&bufcspin);
330 if (runningbufspace > limit) {
331 while (runningbufspace > limit) {
333 ssleep(&runningbufreq, &bufcspin, 0, "wdrn1", 0);
335 spin_unlock(&bufcspin);
336 } else if (runningbufspace > limit / 2) {
338 spin_unlock(&bufcspin);
339 tsleep(&dummy, 0, "wdrn2", 1);
341 spin_unlock(&bufcspin);
346 * buf_dirty_count_severe:
348 * Return true if we have too many dirty buffers.
351 buf_dirty_count_severe(void)
353 return (runningbufspace + dirtybufspace >= hidirtybufspace ||
354 dirtybufcount >= nbuf / 2);
358 * Return true if the amount of running I/O is severe and BIOQ should
362 buf_runningbufspace_severe(void)
364 return (runningbufspace >= hirunningspace * 4 / 6);
368 * vfs_buf_test_cache:
370 * Called when a buffer is extended. This function clears the B_CACHE
371 * bit if the newly extended portion of the buffer does not contain
374 * NOTE! Dirty VM pages are not processed into dirty (B_DELWRI) buffer
375 * cache buffers. The VM pages remain dirty, as someone had mmap()'d
376 * them while a clean buffer was present.
380 vfs_buf_test_cache(struct buf *bp,
381 vm_ooffset_t foff, vm_offset_t off, vm_offset_t size,
384 if (bp->b_flags & B_CACHE) {
385 int base = (foff + off) & PAGE_MASK;
386 if (vm_page_is_valid(m, base, size) == 0)
387 bp->b_flags &= ~B_CACHE;
394 * Spank the buf_daemon[_hw] if the total dirty buffer space exceeds the
403 if (dirtybufspace < lodirtybufspace && dirtybufcount < nbuf / 2)
406 if (bd_request == 0 &&
407 (dirtybufspace - dirtybufspacehw > lodirtybufspace / 2 ||
408 dirtybufcount - dirtybufcounthw >= nbuf / 2)) {
409 spin_lock(&bufcspin);
411 spin_unlock(&bufcspin);
414 if (bd_request_hw == 0 &&
415 (dirtybufspacehw > lodirtybufspace / 2 ||
416 dirtybufcounthw >= nbuf / 2)) {
417 spin_lock(&bufcspin);
419 spin_unlock(&bufcspin);
420 wakeup(&bd_request_hw);
427 * Get the buf_daemon heated up when the number of running and dirty
428 * buffers exceeds the mid-point.
430 * Return the total number of dirty bytes past the second mid point
431 * as a measure of how much excess dirty data there is in the system.
442 mid1 = lodirtybufspace + (hidirtybufspace - lodirtybufspace) / 2;
444 totalspace = runningbufspace + dirtybufspace;
445 if (totalspace >= mid1 || dirtybufcount >= nbuf / 2) {
447 mid2 = mid1 + (hidirtybufspace - mid1) / 2;
448 if (totalspace >= mid2)
449 return(totalspace - mid2);
457 * Wait for the buffer cache to flush (totalspace) bytes worth of
458 * buffers, then return.
460 * Regardless this function blocks while the number of dirty buffers
461 * exceeds hidirtybufspace.
466 bd_wait(int totalspace)
471 if (curthread == bufdaemonhw_td || curthread == bufdaemon_td)
474 while (totalspace > 0) {
476 if (totalspace > runningbufspace + dirtybufspace)
477 totalspace = runningbufspace + dirtybufspace;
478 count = totalspace / BKVASIZE;
479 if (count >= BD_WAKE_SIZE)
480 count = BD_WAKE_SIZE - 1;
482 spin_lock(&bufcspin);
483 i = (bd_wake_index + count) & BD_WAKE_MASK;
487 * This is not a strict interlock, so we play a bit loose
488 * with locking access to dirtybufspace*
490 tsleep_interlock(&bd_wake_ary[i], 0);
491 spin_unlock(&bufcspin);
492 tsleep(&bd_wake_ary[i], PINTERLOCKED, "flstik", hz);
494 totalspace = runningbufspace + dirtybufspace - hidirtybufspace;
501 * This function is called whenever runningbufspace or dirtybufspace
502 * is reduced. Track threads waiting for run+dirty buffer I/O
508 bd_signal(int totalspace)
512 if (totalspace > 0) {
513 if (totalspace > BKVASIZE * BD_WAKE_SIZE)
514 totalspace = BKVASIZE * BD_WAKE_SIZE;
515 spin_lock(&bufcspin);
516 while (totalspace > 0) {
519 if (bd_wake_ary[i]) {
521 spin_unlock(&bufcspin);
522 wakeup(&bd_wake_ary[i]);
523 spin_lock(&bufcspin);
525 totalspace -= BKVASIZE;
527 spin_unlock(&bufcspin);
532 * BIO tracking support routines.
534 * Release a ref on a bio_track. Wakeup requests are atomically released
535 * along with the last reference so bk_active will never wind up set to
542 bio_track_rel(struct bio_track *track)
550 active = track->bk_active;
551 if (active == 1 && atomic_cmpset_int(&track->bk_active, 1, 0))
555 * Full-on. Note that the wait flag is only atomically released on
556 * the 1->0 count transition.
558 * We check for a negative count transition using bit 30 since bit 31
559 * has a different meaning.
562 desired = (active & 0x7FFFFFFF) - 1;
564 desired |= active & 0x80000000;
565 if (atomic_cmpset_int(&track->bk_active, active, desired)) {
566 if (desired & 0x40000000)
567 panic("bio_track_rel: bad count: %p\n", track);
568 if (active & 0x80000000)
572 active = track->bk_active;
577 * Wait for the tracking count to reach 0.
579 * Use atomic ops such that the wait flag is only set atomically when
580 * bk_active is non-zero.
585 bio_track_wait(struct bio_track *track, int slp_flags, int slp_timo)
594 if (track->bk_active == 0)
598 * Full-on. Note that the wait flag may only be atomically set if
599 * the active count is non-zero.
601 * NOTE: We cannot optimize active == desired since a wakeup could
602 * clear active prior to our tsleep_interlock().
605 while ((active = track->bk_active) != 0) {
607 desired = active | 0x80000000;
608 tsleep_interlock(track, slp_flags);
609 if (atomic_cmpset_int(&track->bk_active, active, desired)) {
610 error = tsleep(track, slp_flags | PINTERLOCKED,
622 * Load time initialisation of the buffer cache, called from machine
623 * dependant initialization code.
629 vm_offset_t bogus_offset;
632 /* next, make a null set of free lists */
633 for (i = 0; i < BUFFER_QUEUES; i++)
634 TAILQ_INIT(&bufqueues[i]);
636 /* finally, initialize each buffer header and stick on empty q */
637 for (i = 0; i < nbuf; i++) {
639 bzero(bp, sizeof *bp);
640 bp->b_flags = B_INVAL; /* we're just an empty header */
641 bp->b_cmd = BUF_CMD_DONE;
642 bp->b_qindex = BQUEUE_EMPTY;
644 xio_init(&bp->b_xio);
646 TAILQ_INSERT_TAIL(&bufqueues[BQUEUE_EMPTY], bp, b_freelist);
650 * maxbufspace is the absolute maximum amount of buffer space we are
651 * allowed to reserve in KVM and in real terms. The absolute maximum
652 * is nominally used by buf_daemon. hibufspace is the nominal maximum
653 * used by most other processes. The differential is required to
654 * ensure that buf_daemon is able to run when other processes might
655 * be blocked waiting for buffer space.
657 * maxbufspace is based on BKVASIZE. Allocating buffers larger then
658 * this may result in KVM fragmentation which is not handled optimally
661 maxbufspace = nbuf * BKVASIZE;
662 hibufspace = imax(3 * maxbufspace / 4, maxbufspace - MAXBSIZE * 10);
663 lobufspace = hibufspace - MAXBSIZE;
665 lorunningspace = 512 * 1024;
666 /* hirunningspace -- see below */
669 * Limit the amount of malloc memory since it is wired permanently
670 * into the kernel space. Even though this is accounted for in
671 * the buffer allocation, we don't want the malloced region to grow
672 * uncontrolled. The malloc scheme improves memory utilization
673 * significantly on average (small) directories.
675 maxbufmallocspace = hibufspace / 20;
678 * Reduce the chance of a deadlock occuring by limiting the number
679 * of delayed-write dirty buffers we allow to stack up.
681 * We don't want too much actually queued to the device at once
682 * (XXX this needs to be per-mount!), because the buffers will
683 * wind up locked for a very long period of time while the I/O
686 hidirtybufspace = hibufspace / 2; /* dirty + running */
687 hirunningspace = hibufspace / 16; /* locked & queued to device */
688 if (hirunningspace < 1024 * 1024)
689 hirunningspace = 1024 * 1024;
694 lodirtybufspace = hidirtybufspace / 2;
697 * Maximum number of async ops initiated per buf_daemon loop. This is
698 * somewhat of a hack at the moment, we really need to limit ourselves
699 * based on the number of bytes of I/O in-transit that were initiated
703 bogus_offset = kmem_alloc_pageable(&kernel_map, PAGE_SIZE);
704 bogus_page = vm_page_alloc(&kernel_object,
705 (bogus_offset >> PAGE_SHIFT),
707 vmstats.v_wire_count++;
712 * Initialize the embedded bio structures, typically used by
713 * deprecated code which tries to allocate its own struct bufs.
716 initbufbio(struct buf *bp)
718 bp->b_bio1.bio_buf = bp;
719 bp->b_bio1.bio_prev = NULL;
720 bp->b_bio1.bio_offset = NOOFFSET;
721 bp->b_bio1.bio_next = &bp->b_bio2;
722 bp->b_bio1.bio_done = NULL;
723 bp->b_bio1.bio_flags = 0;
725 bp->b_bio2.bio_buf = bp;
726 bp->b_bio2.bio_prev = &bp->b_bio1;
727 bp->b_bio2.bio_offset = NOOFFSET;
728 bp->b_bio2.bio_next = NULL;
729 bp->b_bio2.bio_done = NULL;
730 bp->b_bio2.bio_flags = 0;
736 * Reinitialize the embedded bio structures as well as any additional
737 * translation cache layers.
740 reinitbufbio(struct buf *bp)
744 for (bio = &bp->b_bio1; bio; bio = bio->bio_next) {
745 bio->bio_done = NULL;
746 bio->bio_offset = NOOFFSET;
751 * Undo the effects of an initbufbio().
754 uninitbufbio(struct buf *bp)
761 * Push another BIO layer onto an existing BIO and return it. The new
762 * BIO layer may already exist, holding cached translation data.
765 push_bio(struct bio *bio)
769 if ((nbio = bio->bio_next) == NULL) {
770 int index = bio - &bio->bio_buf->b_bio_array[0];
771 if (index >= NBUF_BIO - 1) {
772 panic("push_bio: too many layers bp %p\n",
775 nbio = &bio->bio_buf->b_bio_array[index + 1];
776 bio->bio_next = nbio;
777 nbio->bio_prev = bio;
778 nbio->bio_buf = bio->bio_buf;
779 nbio->bio_offset = NOOFFSET;
780 nbio->bio_done = NULL;
781 nbio->bio_next = NULL;
783 KKASSERT(nbio->bio_done == NULL);
788 * Pop a BIO translation layer, returning the previous layer. The
789 * must have been previously pushed.
792 pop_bio(struct bio *bio)
794 return(bio->bio_prev);
798 clearbiocache(struct bio *bio)
801 bio->bio_offset = NOOFFSET;
809 * Free the KVA allocation for buffer 'bp'.
811 * Must be called from a critical section as this is the only locking for
814 * Since this call frees up buffer space, we call bufspacewakeup().
819 bfreekva(struct buf *bp)
825 count = vm_map_entry_reserve(MAP_RESERVE_COUNT);
826 vm_map_lock(&buffer_map);
827 bufspace -= bp->b_kvasize;
828 vm_map_delete(&buffer_map,
829 (vm_offset_t) bp->b_kvabase,
830 (vm_offset_t) bp->b_kvabase + bp->b_kvasize,
833 vm_map_unlock(&buffer_map);
834 vm_map_entry_release(count);
836 bp->b_kvabase = NULL;
844 * Remove the buffer from the appropriate free list.
847 _bremfree(struct buf *bp)
849 if (bp->b_qindex != BQUEUE_NONE) {
850 KASSERT(BUF_REFCNTNB(bp) == 1,
851 ("bremfree: bp %p not locked",bp));
852 TAILQ_REMOVE(&bufqueues[bp->b_qindex], bp, b_freelist);
853 bp->b_qindex = BQUEUE_NONE;
855 if (BUF_REFCNTNB(bp) <= 1)
856 panic("bremfree: removing a buffer not on a queue");
861 bremfree(struct buf *bp)
863 spin_lock(&bufqspin);
865 spin_unlock(&bufqspin);
869 bremfree_locked(struct buf *bp)
877 * Get a buffer with the specified data. Look in the cache first. We
878 * must clear B_ERROR and B_INVAL prior to initiating I/O. If B_CACHE
879 * is set, the buffer is valid and we do not have to do anything ( see
885 bread(struct vnode *vp, off_t loffset, int size, struct buf **bpp)
889 bp = getblk(vp, loffset, size, 0, 0);
892 /* if not found in cache, do some I/O */
893 if ((bp->b_flags & B_CACHE) == 0) {
894 bp->b_flags &= ~(B_ERROR | B_EINTR | B_INVAL);
895 bp->b_cmd = BUF_CMD_READ;
896 bp->b_bio1.bio_done = biodone_sync;
897 bp->b_bio1.bio_flags |= BIO_SYNC;
898 vfs_busy_pages(vp, bp);
899 vn_strategy(vp, &bp->b_bio1);
900 return (biowait(&bp->b_bio1, "biord"));
906 * This version of bread issues any required I/O asyncnronously and
907 * makes a callback on completion.
909 * The callback must check whether BIO_DONE is set in the bio and issue
910 * the bpdone(bp, 0) if it isn't. The callback is responsible for clearing
911 * BIO_DONE and disposing of the I/O (bqrelse()ing it).
914 breadcb(struct vnode *vp, off_t loffset, int size,
915 void (*func)(struct bio *), void *arg)
919 bp = getblk(vp, loffset, size, 0, 0);
921 /* if not found in cache, do some I/O */
922 if ((bp->b_flags & B_CACHE) == 0) {
923 bp->b_flags &= ~(B_ERROR | B_EINTR | B_INVAL);
924 bp->b_cmd = BUF_CMD_READ;
925 bp->b_bio1.bio_done = func;
926 bp->b_bio1.bio_caller_info1.ptr = arg;
927 vfs_busy_pages(vp, bp);
929 vn_strategy(vp, &bp->b_bio1);
932 * Since we are issuing the callback synchronously it cannot
933 * race the BIO_DONE, so no need for atomic ops here.
935 /*bp->b_bio1.bio_done = func;*/
936 bp->b_bio1.bio_caller_info1.ptr = arg;
937 bp->b_bio1.bio_flags |= BIO_DONE;
947 * Operates like bread, but also starts asynchronous I/O on
948 * read-ahead blocks. We must clear B_ERROR and B_INVAL prior
949 * to initiating I/O . If B_CACHE is set, the buffer is valid
950 * and we do not have to do anything.
955 breadn(struct vnode *vp, off_t loffset, int size, off_t *raoffset,
956 int *rabsize, int cnt, struct buf **bpp)
958 struct buf *bp, *rabp;
960 int rv = 0, readwait = 0;
962 *bpp = bp = getblk(vp, loffset, size, 0, 0);
964 /* if not found in cache, do some I/O */
965 if ((bp->b_flags & B_CACHE) == 0) {
966 bp->b_flags &= ~(B_ERROR | B_EINTR | B_INVAL);
967 bp->b_cmd = BUF_CMD_READ;
968 bp->b_bio1.bio_done = biodone_sync;
969 bp->b_bio1.bio_flags |= BIO_SYNC;
970 vfs_busy_pages(vp, bp);
971 vn_strategy(vp, &bp->b_bio1);
975 for (i = 0; i < cnt; i++, raoffset++, rabsize++) {
976 if (inmem(vp, *raoffset))
978 rabp = getblk(vp, *raoffset, *rabsize, 0, 0);
980 if ((rabp->b_flags & B_CACHE) == 0) {
981 rabp->b_flags &= ~(B_ERROR | B_EINTR | B_INVAL);
982 rabp->b_cmd = BUF_CMD_READ;
983 vfs_busy_pages(vp, rabp);
985 vn_strategy(vp, &rabp->b_bio1);
991 rv = biowait(&bp->b_bio1, "biord");
998 * Synchronous write, waits for completion.
1000 * Write, release buffer on completion. (Done by iodone
1001 * if async). Do not bother writing anything if the buffer
1004 * Note that we set B_CACHE here, indicating that buffer is
1005 * fully valid and thus cacheable. This is true even of NFS
1006 * now so we set it generally. This could be set either here
1007 * or in biodone() since the I/O is synchronous. We put it
1011 bwrite(struct buf *bp)
1015 if (bp->b_flags & B_INVAL) {
1019 if (BUF_REFCNTNB(bp) == 0)
1020 panic("bwrite: buffer is not busy???");
1022 /* Mark the buffer clean */
1025 bp->b_flags &= ~(B_ERROR | B_EINTR);
1026 bp->b_flags |= B_CACHE;
1027 bp->b_cmd = BUF_CMD_WRITE;
1028 bp->b_bio1.bio_done = biodone_sync;
1029 bp->b_bio1.bio_flags |= BIO_SYNC;
1030 vfs_busy_pages(bp->b_vp, bp);
1033 * Normal bwrites pipeline writes. NOTE: b_bufsize is only
1034 * valid for vnode-backed buffers.
1036 bsetrunningbufspace(bp, bp->b_bufsize);
1037 vn_strategy(bp->b_vp, &bp->b_bio1);
1038 error = biowait(&bp->b_bio1, "biows");
1047 * Asynchronous write. Start output on a buffer, but do not wait for
1048 * it to complete. The buffer is released when the output completes.
1050 * bwrite() ( or the VOP routine anyway ) is responsible for handling
1051 * B_INVAL buffers. Not us.
1054 bawrite(struct buf *bp)
1056 if (bp->b_flags & B_INVAL) {
1060 if (BUF_REFCNTNB(bp) == 0)
1061 panic("bwrite: buffer is not busy???");
1063 /* Mark the buffer clean */
1066 bp->b_flags &= ~(B_ERROR | B_EINTR);
1067 bp->b_flags |= B_CACHE;
1068 bp->b_cmd = BUF_CMD_WRITE;
1069 KKASSERT(bp->b_bio1.bio_done == NULL);
1070 vfs_busy_pages(bp->b_vp, bp);
1073 * Normal bwrites pipeline writes. NOTE: b_bufsize is only
1074 * valid for vnode-backed buffers.
1076 bsetrunningbufspace(bp, bp->b_bufsize);
1078 vn_strategy(bp->b_vp, &bp->b_bio1);
1084 * Ordered write. Start output on a buffer, and flag it so that the
1085 * device will write it in the order it was queued. The buffer is
1086 * released when the output completes. bwrite() ( or the VOP routine
1087 * anyway ) is responsible for handling B_INVAL buffers.
1090 bowrite(struct buf *bp)
1092 bp->b_flags |= B_ORDERED;
1100 * Delayed write. (Buffer is marked dirty). Do not bother writing
1101 * anything if the buffer is marked invalid.
1103 * Note that since the buffer must be completely valid, we can safely
1104 * set B_CACHE. In fact, we have to set B_CACHE here rather then in
1105 * biodone() in order to prevent getblk from writing the buffer
1106 * out synchronously.
1109 bdwrite(struct buf *bp)
1111 if (BUF_REFCNTNB(bp) == 0)
1112 panic("bdwrite: buffer is not busy");
1114 if (bp->b_flags & B_INVAL) {
1120 if (dsched_is_clear_buf_priv(bp))
1124 * Set B_CACHE, indicating that the buffer is fully valid. This is
1125 * true even of NFS now.
1127 bp->b_flags |= B_CACHE;
1130 * This bmap keeps the system from needing to do the bmap later,
1131 * perhaps when the system is attempting to do a sync. Since it
1132 * is likely that the indirect block -- or whatever other datastructure
1133 * that the filesystem needs is still in memory now, it is a good
1134 * thing to do this. Note also, that if the pageout daemon is
1135 * requesting a sync -- there might not be enough memory to do
1136 * the bmap then... So, this is important to do.
1138 if (bp->b_bio2.bio_offset == NOOFFSET) {
1139 VOP_BMAP(bp->b_vp, bp->b_loffset, &bp->b_bio2.bio_offset,
1140 NULL, NULL, BUF_CMD_WRITE);
1144 * Because the underlying pages may still be mapped and
1145 * writable trying to set the dirty buffer (b_dirtyoff/end)
1146 * range here will be inaccurate.
1148 * However, we must still clean the pages to satisfy the
1149 * vnode_pager and pageout daemon, so theythink the pages
1150 * have been "cleaned". What has really occured is that
1151 * they've been earmarked for later writing by the buffer
1154 * So we get the b_dirtyoff/end update but will not actually
1155 * depend on it (NFS that is) until the pages are busied for
1158 vfs_clean_pages(bp);
1162 * note: we cannot initiate I/O from a bdwrite even if we wanted to,
1163 * due to the softdep code.
1168 * Fake write - return pages to VM system as dirty, leave the buffer clean.
1169 * This is used by tmpfs.
1171 * It is important for any VFS using this routine to NOT use it for
1172 * IO_SYNC or IO_ASYNC operations which occur when the system really
1173 * wants to flush VM pages to backing store.
1176 buwrite(struct buf *bp)
1182 * Only works for VMIO buffers. If the buffer is already
1183 * marked for delayed-write we can't avoid the bdwrite().
1185 if ((bp->b_flags & B_VMIO) == 0 || (bp->b_flags & B_DELWRI)) {
1191 * Set valid & dirty.
1193 * WARNING! vfs_dirty_one_page() assumes vm_token is held for now.
1195 lwkt_gettoken(&vm_token);
1196 for (i = 0; i < bp->b_xio.xio_npages; i++) {
1197 m = bp->b_xio.xio_pages[i];
1198 vfs_dirty_one_page(bp, i, m);
1200 lwkt_reltoken(&vm_token);
1207 * Turn buffer into delayed write request by marking it B_DELWRI.
1208 * B_RELBUF and B_NOCACHE must be cleared.
1210 * We reassign the buffer to itself to properly update it in the
1211 * dirty/clean lists.
1213 * Must be called from a critical section.
1214 * The buffer must be on BQUEUE_NONE.
1217 bdirty(struct buf *bp)
1219 KASSERT(bp->b_qindex == BQUEUE_NONE, ("bdirty: buffer %p still on queue %d", bp, bp->b_qindex));
1220 if (bp->b_flags & B_NOCACHE) {
1221 kprintf("bdirty: clearing B_NOCACHE on buf %p\n", bp);
1222 bp->b_flags &= ~B_NOCACHE;
1224 if (bp->b_flags & B_INVAL) {
1225 kprintf("bdirty: warning, dirtying invalid buffer %p\n", bp);
1227 bp->b_flags &= ~B_RELBUF;
1229 if ((bp->b_flags & B_DELWRI) == 0) {
1230 lwkt_gettoken(&bp->b_vp->v_token);
1231 bp->b_flags |= B_DELWRI;
1233 lwkt_reltoken(&bp->b_vp->v_token);
1235 spin_lock(&bufcspin);
1237 dirtybufspace += bp->b_bufsize;
1238 if (bp->b_flags & B_HEAVY) {
1240 dirtybufspacehw += bp->b_bufsize;
1242 spin_unlock(&bufcspin);
1249 * Set B_HEAVY, indicating that this is a heavy-weight buffer that
1250 * needs to be flushed with a different buf_daemon thread to avoid
1251 * deadlocks. B_HEAVY also imposes restrictions in getnewbuf().
1254 bheavy(struct buf *bp)
1256 if ((bp->b_flags & B_HEAVY) == 0) {
1257 bp->b_flags |= B_HEAVY;
1258 if (bp->b_flags & B_DELWRI) {
1259 spin_lock(&bufcspin);
1261 dirtybufspacehw += bp->b_bufsize;
1262 spin_unlock(&bufcspin);
1270 * Clear B_DELWRI for buffer.
1272 * Must be called from a critical section.
1274 * The buffer is typically on BQUEUE_NONE but there is one case in
1275 * brelse() that calls this function after placing the buffer on
1276 * a different queue.
1281 bundirty(struct buf *bp)
1283 if (bp->b_flags & B_DELWRI) {
1284 lwkt_gettoken(&bp->b_vp->v_token);
1285 bp->b_flags &= ~B_DELWRI;
1287 lwkt_reltoken(&bp->b_vp->v_token);
1289 spin_lock(&bufcspin);
1291 dirtybufspace -= bp->b_bufsize;
1292 if (bp->b_flags & B_HEAVY) {
1294 dirtybufspacehw -= bp->b_bufsize;
1296 spin_unlock(&bufcspin);
1298 bd_signal(bp->b_bufsize);
1301 * Since it is now being written, we can clear its deferred write flag.
1303 bp->b_flags &= ~B_DEFERRED;
1307 * Set the b_runningbufspace field, used to track how much I/O is
1308 * in progress at any given moment.
1311 bsetrunningbufspace(struct buf *bp, int bytes)
1313 bp->b_runningbufspace = bytes;
1315 spin_lock(&bufcspin);
1316 runningbufspace += bytes;
1318 spin_unlock(&bufcspin);
1325 * Release a busy buffer and, if requested, free its resources. The
1326 * buffer will be stashed in the appropriate bufqueue[] allowing it
1327 * to be accessed later as a cache entity or reused for other purposes.
1332 brelse(struct buf *bp)
1335 int saved_flags = bp->b_flags;
1338 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)), ("brelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp));
1341 * If B_NOCACHE is set we are being asked to destroy the buffer and
1342 * its backing store. Clear B_DELWRI.
1344 * B_NOCACHE is set in two cases: (1) when the caller really wants
1345 * to destroy the buffer and backing store and (2) when the caller
1346 * wants to destroy the buffer and backing store after a write
1349 if ((bp->b_flags & (B_NOCACHE|B_DELWRI)) == (B_NOCACHE|B_DELWRI)) {
1353 if ((bp->b_flags & (B_INVAL | B_DELWRI)) == B_DELWRI) {
1355 * A re-dirtied buffer is only subject to destruction
1356 * by B_INVAL. B_ERROR and B_NOCACHE are ignored.
1358 /* leave buffer intact */
1359 } else if ((bp->b_flags & (B_NOCACHE | B_INVAL | B_ERROR)) ||
1360 (bp->b_bufsize <= 0)) {
1362 * Either a failed read or we were asked to free or not
1363 * cache the buffer. This path is reached with B_DELWRI
1364 * set only if B_INVAL is already set. B_NOCACHE governs
1365 * backing store destruction.
1367 * NOTE: HAMMER will set B_LOCKED in buf_deallocate if the
1368 * buffer cannot be immediately freed.
1370 bp->b_flags |= B_INVAL;
1371 if (LIST_FIRST(&bp->b_dep) != NULL)
1373 if (bp->b_flags & B_DELWRI) {
1374 spin_lock(&bufcspin);
1376 dirtybufspace -= bp->b_bufsize;
1377 if (bp->b_flags & B_HEAVY) {
1379 dirtybufspacehw -= bp->b_bufsize;
1381 spin_unlock(&bufcspin);
1383 bd_signal(bp->b_bufsize);
1385 bp->b_flags &= ~(B_DELWRI | B_CACHE);
1389 * We must clear B_RELBUF if B_DELWRI or B_LOCKED is set,
1390 * or if b_refs is non-zero.
1392 * If vfs_vmio_release() is called with either bit set, the
1393 * underlying pages may wind up getting freed causing a previous
1394 * write (bdwrite()) to get 'lost' because pages associated with
1395 * a B_DELWRI bp are marked clean. Pages associated with a
1396 * B_LOCKED buffer may be mapped by the filesystem.
1398 * If we want to release the buffer ourselves (rather then the
1399 * originator asking us to release it), give the originator a
1400 * chance to countermand the release by setting B_LOCKED.
1402 * We still allow the B_INVAL case to call vfs_vmio_release(), even
1403 * if B_DELWRI is set.
1405 * If B_DELWRI is not set we may have to set B_RELBUF if we are low
1406 * on pages to return pages to the VM page queues.
1408 if ((bp->b_flags & (B_DELWRI | B_LOCKED)) || bp->b_refs) {
1409 bp->b_flags &= ~B_RELBUF;
1410 } else if (vm_page_count_severe()) {
1411 if (LIST_FIRST(&bp->b_dep) != NULL)
1412 buf_deallocate(bp); /* can set B_LOCKED */
1413 if (bp->b_flags & (B_DELWRI | B_LOCKED))
1414 bp->b_flags &= ~B_RELBUF;
1416 bp->b_flags |= B_RELBUF;
1420 * Make sure b_cmd is clear. It may have already been cleared by
1423 * At this point destroying the buffer is governed by the B_INVAL
1424 * or B_RELBUF flags.
1426 bp->b_cmd = BUF_CMD_DONE;
1427 dsched_exit_buf(bp);
1430 * VMIO buffer rundown. Make sure the VM page array is restored
1431 * after an I/O may have replaces some of the pages with bogus pages
1432 * in order to not destroy dirty pages in a fill-in read.
1434 * Note that due to the code above, if a buffer is marked B_DELWRI
1435 * then the B_RELBUF and B_NOCACHE bits will always be clear.
1436 * B_INVAL may still be set, however.
1438 * For clean buffers, B_INVAL or B_RELBUF will destroy the buffer
1439 * but not the backing store. B_NOCACHE will destroy the backing
1442 * Note that dirty NFS buffers contain byte-granular write ranges
1443 * and should not be destroyed w/ B_INVAL even if the backing store
1446 if (bp->b_flags & B_VMIO) {
1448 * Rundown for VMIO buffers which are not dirty NFS buffers.
1460 * Get the base offset and length of the buffer. Note that
1461 * in the VMIO case if the buffer block size is not
1462 * page-aligned then b_data pointer may not be page-aligned.
1463 * But our b_xio.xio_pages array *IS* page aligned.
1465 * block sizes less then DEV_BSIZE (usually 512) are not
1466 * supported due to the page granularity bits (m->valid,
1467 * m->dirty, etc...).
1469 * See man buf(9) for more information
1472 resid = bp->b_bufsize;
1473 foff = bp->b_loffset;
1475 lwkt_gettoken(&vm_token);
1476 for (i = 0; i < bp->b_xio.xio_npages; i++) {
1477 m = bp->b_xio.xio_pages[i];
1478 vm_page_flag_clear(m, PG_ZERO);
1480 * If we hit a bogus page, fixup *all* of them
1481 * now. Note that we left these pages wired
1482 * when we removed them so they had better exist,
1483 * and they cannot be ripped out from under us so
1484 * no critical section protection is necessary.
1486 if (m == bogus_page) {
1488 poff = OFF_TO_IDX(bp->b_loffset);
1490 for (j = i; j < bp->b_xio.xio_npages; j++) {
1493 mtmp = bp->b_xio.xio_pages[j];
1494 if (mtmp == bogus_page) {
1495 mtmp = vm_page_lookup(obj, poff + j);
1497 panic("brelse: page missing");
1499 bp->b_xio.xio_pages[j] = mtmp;
1502 bp->b_flags &= ~B_HASBOGUS;
1504 if ((bp->b_flags & B_INVAL) == 0) {
1505 pmap_qenter(trunc_page((vm_offset_t)bp->b_data),
1506 bp->b_xio.xio_pages, bp->b_xio.xio_npages);
1508 m = bp->b_xio.xio_pages[i];
1512 * Invalidate the backing store if B_NOCACHE is set
1513 * (e.g. used with vinvalbuf()). If this is NFS
1514 * we impose a requirement that the block size be
1515 * a multiple of PAGE_SIZE and create a temporary
1516 * hack to basically invalidate the whole page. The
1517 * problem is that NFS uses really odd buffer sizes
1518 * especially when tracking piecemeal writes and
1519 * it also vinvalbuf()'s a lot, which would result
1520 * in only partial page validation and invalidation
1521 * here. If the file page is mmap()'d, however,
1522 * all the valid bits get set so after we invalidate
1523 * here we would end up with weird m->valid values
1524 * like 0xfc. nfs_getpages() can't handle this so
1525 * we clear all the valid bits for the NFS case
1526 * instead of just some of them.
1528 * The real bug is the VM system having to set m->valid
1529 * to VM_PAGE_BITS_ALL for faulted-in pages, which
1530 * itself is an artifact of the whole 512-byte
1531 * granular mess that exists to support odd block
1532 * sizes and UFS meta-data block sizes (e.g. 6144).
1533 * A complete rewrite is required.
1537 if (bp->b_flags & (B_NOCACHE|B_ERROR)) {
1538 int poffset = foff & PAGE_MASK;
1541 presid = PAGE_SIZE - poffset;
1542 if (bp->b_vp->v_tag == VT_NFS &&
1543 bp->b_vp->v_type == VREG) {
1545 } else if (presid > resid) {
1548 KASSERT(presid >= 0, ("brelse: extra page"));
1549 vm_page_set_invalid(m, poffset, presid);
1552 * Also make sure any swap cache is removed
1553 * as it is now stale (HAMMER in particular
1554 * uses B_NOCACHE to deal with buffer
1557 swap_pager_unswapped(m);
1559 resid -= PAGE_SIZE - (foff & PAGE_MASK);
1560 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK;
1562 if (bp->b_flags & (B_INVAL | B_RELBUF))
1563 vfs_vmio_release(bp);
1564 lwkt_reltoken(&vm_token);
1567 * Rundown for non-VMIO buffers.
1569 if (bp->b_flags & (B_INVAL | B_RELBUF)) {
1572 KKASSERT (LIST_FIRST(&bp->b_dep) == NULL);
1578 if (bp->b_qindex != BQUEUE_NONE)
1579 panic("brelse: free buffer onto another queue???");
1580 if (BUF_REFCNTNB(bp) > 1) {
1581 /* Temporary panic to verify exclusive locking */
1582 /* This panic goes away when we allow shared refs */
1583 panic("brelse: multiple refs");
1589 * Figure out the correct queue to place the cleaned up buffer on.
1590 * Buffers placed in the EMPTY or EMPTYKVA had better already be
1591 * disassociated from their vnode.
1593 spin_lock(&bufqspin);
1594 if (bp->b_flags & B_LOCKED) {
1596 * Buffers that are locked are placed in the locked queue
1597 * immediately, regardless of their state.
1599 bp->b_qindex = BQUEUE_LOCKED;
1600 TAILQ_INSERT_TAIL(&bufqueues[BQUEUE_LOCKED], bp, b_freelist);
1601 } else if (bp->b_bufsize == 0) {
1603 * Buffers with no memory. Due to conditionals near the top
1604 * of brelse() such buffers should probably already be
1605 * marked B_INVAL and disassociated from their vnode.
1607 bp->b_flags |= B_INVAL;
1608 KASSERT(bp->b_vp == NULL, ("bp1 %p flags %08x/%08x vnode %p unexpectededly still associated!", bp, saved_flags, bp->b_flags, bp->b_vp));
1609 KKASSERT((bp->b_flags & B_HASHED) == 0);
1610 if (bp->b_kvasize) {
1611 bp->b_qindex = BQUEUE_EMPTYKVA;
1613 bp->b_qindex = BQUEUE_EMPTY;
1615 TAILQ_INSERT_HEAD(&bufqueues[bp->b_qindex], bp, b_freelist);
1616 } else if (bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF)) {
1618 * Buffers with junk contents. Again these buffers had better
1619 * already be disassociated from their vnode.
1621 KASSERT(bp->b_vp == NULL, ("bp2 %p flags %08x/%08x vnode %p unexpectededly still associated!", bp, saved_flags, bp->b_flags, bp->b_vp));
1622 KKASSERT((bp->b_flags & B_HASHED) == 0);
1623 bp->b_flags |= B_INVAL;
1624 bp->b_qindex = BQUEUE_CLEAN;
1625 TAILQ_INSERT_HEAD(&bufqueues[BQUEUE_CLEAN], bp, b_freelist);
1628 * Remaining buffers. These buffers are still associated with
1631 switch(bp->b_flags & (B_DELWRI|B_HEAVY)) {
1633 bp->b_qindex = BQUEUE_DIRTY;
1634 TAILQ_INSERT_TAIL(&bufqueues[BQUEUE_DIRTY], bp, b_freelist);
1636 case B_DELWRI | B_HEAVY:
1637 bp->b_qindex = BQUEUE_DIRTY_HW;
1638 TAILQ_INSERT_TAIL(&bufqueues[BQUEUE_DIRTY_HW], bp,
1643 * NOTE: Buffers are always placed at the end of the
1644 * queue. If B_AGE is not set the buffer will cycle
1645 * through the queue twice.
1647 bp->b_qindex = BQUEUE_CLEAN;
1648 TAILQ_INSERT_TAIL(&bufqueues[BQUEUE_CLEAN], bp, b_freelist);
1652 spin_unlock(&bufqspin);
1655 * If B_INVAL, clear B_DELWRI. We've already placed the buffer
1656 * on the correct queue.
1658 if ((bp->b_flags & (B_INVAL|B_DELWRI)) == (B_INVAL|B_DELWRI))
1662 * The bp is on an appropriate queue unless locked. If it is not
1663 * locked or dirty we can wakeup threads waiting for buffer space.
1665 * We've already handled the B_INVAL case ( B_DELWRI will be clear
1666 * if B_INVAL is set ).
1668 if ((bp->b_flags & (B_LOCKED|B_DELWRI)) == 0)
1672 * Something we can maybe free or reuse
1674 if (bp->b_bufsize || bp->b_kvasize)
1678 * Clean up temporary flags and unlock the buffer.
1680 bp->b_flags &= ~(B_ORDERED | B_NOCACHE | B_RELBUF | B_DIRECT);
1687 * Release a buffer back to the appropriate queue but do not try to free
1688 * it. The buffer is expected to be used again soon.
1690 * bqrelse() is used by bdwrite() to requeue a delayed write, and used by
1691 * biodone() to requeue an async I/O on completion. It is also used when
1692 * known good buffers need to be requeued but we think we may need the data
1695 * XXX we should be able to leave the B_RELBUF hint set on completion.
1700 bqrelse(struct buf *bp)
1702 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)), ("bqrelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp));
1704 if (bp->b_qindex != BQUEUE_NONE)
1705 panic("bqrelse: free buffer onto another queue???");
1706 if (BUF_REFCNTNB(bp) > 1) {
1707 /* do not release to free list */
1708 panic("bqrelse: multiple refs");
1712 buf_act_advance(bp);
1714 spin_lock(&bufqspin);
1715 if (bp->b_flags & B_LOCKED) {
1717 * Locked buffers are released to the locked queue. However,
1718 * if the buffer is dirty it will first go into the dirty
1719 * queue and later on after the I/O completes successfully it
1720 * will be released to the locked queue.
1722 bp->b_qindex = BQUEUE_LOCKED;
1723 TAILQ_INSERT_TAIL(&bufqueues[BQUEUE_LOCKED], bp, b_freelist);
1724 } else if (bp->b_flags & B_DELWRI) {
1725 bp->b_qindex = (bp->b_flags & B_HEAVY) ?
1726 BQUEUE_DIRTY_HW : BQUEUE_DIRTY;
1727 TAILQ_INSERT_TAIL(&bufqueues[bp->b_qindex], bp, b_freelist);
1728 } else if (vm_page_count_severe()) {
1730 * We are too low on memory, we have to try to free the
1731 * buffer (most importantly: the wired pages making up its
1732 * backing store) *now*.
1734 spin_unlock(&bufqspin);
1738 bp->b_qindex = BQUEUE_CLEAN;
1739 TAILQ_INSERT_TAIL(&bufqueues[BQUEUE_CLEAN], bp, b_freelist);
1741 spin_unlock(&bufqspin);
1743 if ((bp->b_flags & B_LOCKED) == 0 &&
1744 ((bp->b_flags & B_INVAL) || (bp->b_flags & B_DELWRI) == 0)) {
1749 * Something we can maybe free or reuse.
1751 if (bp->b_bufsize && !(bp->b_flags & B_DELWRI))
1755 * Final cleanup and unlock. Clear bits that are only used while a
1756 * buffer is actively locked.
1758 bp->b_flags &= ~(B_ORDERED | B_NOCACHE | B_RELBUF);
1759 dsched_exit_buf(bp);
1764 * Hold a buffer, preventing it from being reused. This will prevent
1765 * normal B_RELBUF operations on the buffer but will not prevent B_INVAL
1766 * operations. If a B_INVAL operation occurs the buffer will remain held
1767 * but the underlying pages may get ripped out.
1769 * These functions are typically used in VOP_READ/VOP_WRITE functions
1770 * to hold a buffer during a copyin or copyout, preventing deadlocks
1771 * or recursive lock panics when read()/write() is used over mmap()'d
1774 * NOTE: bqhold() requires that the buffer be locked at the time of the
1775 * hold. bqdrop() has no requirements other than the buffer having
1776 * previously been held.
1779 bqhold(struct buf *bp)
1781 atomic_add_int(&bp->b_refs, 1);
1785 bqdrop(struct buf *bp)
1787 KKASSERT(bp->b_refs > 0);
1788 atomic_add_int(&bp->b_refs, -1);
1794 * Return backing pages held by the buffer 'bp' back to the VM system
1795 * if possible. The pages are freed if they are no longer valid or
1796 * attempt to free if it was used for direct I/O otherwise they are
1797 * sent to the page cache.
1799 * Pages that were marked busy are left alone and skipped.
1801 * The KVA mapping (b_data) for the underlying pages is removed by
1805 vfs_vmio_release(struct buf *bp)
1810 lwkt_gettoken(&vm_token);
1811 for (i = 0; i < bp->b_xio.xio_npages; i++) {
1812 m = bp->b_xio.xio_pages[i];
1813 bp->b_xio.xio_pages[i] = NULL;
1816 * The VFS is telling us this is not a meta-data buffer
1817 * even if it is backed by a block device.
1819 if (bp->b_flags & B_NOTMETA)
1820 vm_page_flag_set(m, PG_NOTMETA);
1823 * This is a very important bit of code. We try to track
1824 * VM page use whether the pages are wired into the buffer
1825 * cache or not. While wired into the buffer cache the
1826 * bp tracks the act_count.
1828 * We can choose to place unwired pages on the inactive
1829 * queue (0) or active queue (1). If we place too many
1830 * on the active queue the queue will cycle the act_count
1831 * on pages we'd like to keep, just from single-use pages
1832 * (such as when doing a tar-up or file scan).
1834 if (bp->b_act_count < vm_cycle_point)
1835 vm_page_unwire(m, 0);
1837 vm_page_unwire(m, 1);
1840 * We don't mess with busy pages, it is the responsibility
1841 * of the process that busied the pages to deal with them.
1843 * However, the caller may have marked the page invalid and
1844 * we must still make sure the page is no longer mapped.
1846 if ((m->flags & PG_BUSY) || (m->busy != 0)) {
1847 vm_page_protect(m, VM_PROT_NONE);
1851 if (m->wire_count == 0) {
1852 vm_page_flag_clear(m, PG_ZERO);
1854 * Might as well free the page if we can and it has
1855 * no valid data. We also free the page if the
1856 * buffer was used for direct I/O.
1859 if ((bp->b_flags & B_ASYNC) == 0 && !m->valid &&
1860 m->hold_count == 0) {
1862 vm_page_protect(m, VM_PROT_NONE);
1867 * Cache the page if we are really low on free
1870 * Also bypass the active and inactive queues
1871 * if B_NOTMETA is set. This flag is set by HAMMER
1872 * on a regular file buffer when double buffering
1873 * is enabled or on a block device buffer representing
1874 * file data when double buffering is not enabled.
1875 * The flag prevents two copies of the same data from
1876 * being cached for long periods of time.
1878 if (bp->b_flags & B_DIRECT) {
1879 vm_page_try_to_free(m);
1880 } else if ((bp->b_flags & B_NOTMETA) ||
1881 vm_page_count_severe()) {
1882 m->act_count = bp->b_act_count;
1883 vm_page_try_to_cache(m);
1885 m->act_count = bp->b_act_count;
1889 lwkt_reltoken(&vm_token);
1891 pmap_qremove(trunc_page((vm_offset_t) bp->b_data),
1892 bp->b_xio.xio_npages);
1893 if (bp->b_bufsize) {
1897 bp->b_xio.xio_npages = 0;
1898 bp->b_flags &= ~B_VMIO;
1899 KKASSERT (LIST_FIRST(&bp->b_dep) == NULL);
1907 * Implement clustered async writes for clearing out B_DELWRI buffers.
1908 * This is much better then the old way of writing only one buffer at
1909 * a time. Note that we may not be presented with the buffers in the
1910 * correct order, so we search for the cluster in both directions.
1912 * The buffer is locked on call.
1915 vfs_bio_awrite(struct buf *bp)
1919 off_t loffset = bp->b_loffset;
1920 struct vnode *vp = bp->b_vp;
1927 * right now we support clustered writing only to regular files. If
1928 * we find a clusterable block we could be in the middle of a cluster
1929 * rather then at the beginning.
1931 * NOTE: b_bio1 contains the logical loffset and is aliased
1932 * to b_loffset. b_bio2 contains the translated block number.
1934 if ((vp->v_type == VREG) &&
1935 (vp->v_mount != 0) && /* Only on nodes that have the size info */
1936 (bp->b_flags & (B_CLUSTEROK | B_INVAL)) == B_CLUSTEROK) {
1938 size = vp->v_mount->mnt_stat.f_iosize;
1940 for (i = size; i < MAXPHYS; i += size) {
1941 if ((bpa = findblk(vp, loffset + i, FINDBLK_TEST)) &&
1942 BUF_REFCNT(bpa) == 0 &&
1943 ((bpa->b_flags & (B_DELWRI | B_CLUSTEROK | B_INVAL)) ==
1944 (B_DELWRI | B_CLUSTEROK)) &&
1945 (bpa->b_bufsize == size)) {
1946 if ((bpa->b_bio2.bio_offset == NOOFFSET) ||
1947 (bpa->b_bio2.bio_offset !=
1948 bp->b_bio2.bio_offset + i))
1954 for (j = size; i + j <= MAXPHYS && j <= loffset; j += size) {
1955 if ((bpa = findblk(vp, loffset - j, FINDBLK_TEST)) &&
1956 BUF_REFCNT(bpa) == 0 &&
1957 ((bpa->b_flags & (B_DELWRI | B_CLUSTEROK | B_INVAL)) ==
1958 (B_DELWRI | B_CLUSTEROK)) &&
1959 (bpa->b_bufsize == size)) {
1960 if ((bpa->b_bio2.bio_offset == NOOFFSET) ||
1961 (bpa->b_bio2.bio_offset !=
1962 bp->b_bio2.bio_offset - j))
1972 * this is a possible cluster write
1974 if (nbytes != size) {
1976 nwritten = cluster_wbuild(vp, size,
1977 loffset - j, nbytes);
1983 * default (old) behavior, writing out only one block
1985 * XXX returns b_bufsize instead of b_bcount for nwritten?
1987 nwritten = bp->b_bufsize;
1997 * Find and initialize a new buffer header, freeing up existing buffers
1998 * in the bufqueues as necessary. The new buffer is returned locked.
2000 * Important: B_INVAL is not set. If the caller wishes to throw the
2001 * buffer away, the caller must set B_INVAL prior to calling brelse().
2004 * We have insufficient buffer headers
2005 * We have insufficient buffer space
2006 * buffer_map is too fragmented ( space reservation fails )
2007 * If we have to flush dirty buffers ( but we try to avoid this )
2009 * To avoid VFS layer recursion we do not flush dirty buffers ourselves.
2010 * Instead we ask the buf daemon to do it for us. We attempt to
2011 * avoid piecemeal wakeups of the pageout daemon.
2016 getnewbuf(int blkflags, int slptimeo, int size, int maxsize)
2022 int slpflags = (blkflags & GETBLK_PCATCH) ? PCATCH : 0;
2023 static int flushingbufs;
2026 * We can't afford to block since we might be holding a vnode lock,
2027 * which may prevent system daemons from running. We deal with
2028 * low-memory situations by proactively returning memory and running
2029 * async I/O rather then sync I/O.
2033 --getnewbufrestarts;
2035 ++getnewbufrestarts;
2038 * Setup for scan. If we do not have enough free buffers,
2039 * we setup a degenerate case that immediately fails. Note
2040 * that if we are specially marked process, we are allowed to
2041 * dip into our reserves.
2043 * The scanning sequence is nominally: EMPTY->EMPTYKVA->CLEAN
2045 * We start with EMPTYKVA. If the list is empty we backup to EMPTY.
2046 * However, there are a number of cases (defragging, reusing, ...)
2047 * where we cannot backup.
2049 nqindex = BQUEUE_EMPTYKVA;
2050 spin_lock(&bufqspin);
2051 nbp = TAILQ_FIRST(&bufqueues[BQUEUE_EMPTYKVA]);
2055 * If no EMPTYKVA buffers and we are either
2056 * defragging or reusing, locate a CLEAN buffer
2057 * to free or reuse. If bufspace useage is low
2058 * skip this step so we can allocate a new buffer.
2060 if (defrag || bufspace >= lobufspace) {
2061 nqindex = BQUEUE_CLEAN;
2062 nbp = TAILQ_FIRST(&bufqueues[BQUEUE_CLEAN]);
2066 * If we could not find or were not allowed to reuse a
2067 * CLEAN buffer, check to see if it is ok to use an EMPTY
2068 * buffer. We can only use an EMPTY buffer if allocating
2069 * its KVA would not otherwise run us out of buffer space.
2071 if (nbp == NULL && defrag == 0 &&
2072 bufspace + maxsize < hibufspace) {
2073 nqindex = BQUEUE_EMPTY;
2074 nbp = TAILQ_FIRST(&bufqueues[BQUEUE_EMPTY]);
2079 * Run scan, possibly freeing data and/or kva mappings on the fly
2082 * WARNING! bufqspin is held!
2084 while ((bp = nbp) != NULL) {
2085 int qindex = nqindex;
2087 nbp = TAILQ_NEXT(bp, b_freelist);
2090 * BQUEUE_CLEAN - B_AGE special case. If not set the bp
2091 * cycles through the queue twice before being selected.
2093 if (qindex == BQUEUE_CLEAN &&
2094 (bp->b_flags & B_AGE) == 0 && nbp) {
2095 bp->b_flags |= B_AGE;
2096 TAILQ_REMOVE(&bufqueues[qindex], bp, b_freelist);
2097 TAILQ_INSERT_TAIL(&bufqueues[qindex], bp, b_freelist);
2102 * Calculate next bp ( we can only use it if we do not block
2103 * or do other fancy things ).
2108 nqindex = BQUEUE_EMPTYKVA;
2109 if ((nbp = TAILQ_FIRST(&bufqueues[BQUEUE_EMPTYKVA])))
2112 case BQUEUE_EMPTYKVA:
2113 nqindex = BQUEUE_CLEAN;
2114 if ((nbp = TAILQ_FIRST(&bufqueues[BQUEUE_CLEAN])))
2128 KASSERT(bp->b_qindex == qindex,
2129 ("getnewbuf: inconsistent queue %d bp %p", qindex, bp));
2132 * Note: we no longer distinguish between VMIO and non-VMIO
2135 KASSERT((bp->b_flags & B_DELWRI) == 0,
2136 ("delwri buffer %p found in queue %d", bp, qindex));
2139 * Do not try to reuse a buffer with a non-zero b_refs.
2140 * This is an unsynchronized test. A synchronized test
2141 * is also performed after we lock the buffer.
2147 * If we are defragging then we need a buffer with
2148 * b_kvasize != 0. XXX this situation should no longer
2149 * occur, if defrag is non-zero the buffer's b_kvasize
2150 * should also be non-zero at this point. XXX
2152 if (defrag && bp->b_kvasize == 0) {
2153 kprintf("Warning: defrag empty buffer %p\n", bp);
2158 * Start freeing the bp. This is somewhat involved. nbp
2159 * remains valid only for BQUEUE_EMPTY[KVA] bp's. Buffers
2160 * on the clean list must be disassociated from their
2161 * current vnode. Buffers on the empty[kva] lists have
2162 * already been disassociated.
2164 * b_refs is checked after locking along with queue changes.
2165 * We must check here to deal with zero->nonzero transitions
2166 * made by the owner of the buffer lock, which is used by
2167 * VFS's to hold the buffer while issuing an unlocked
2168 * uiomove()s. We cannot invalidate the buffer's pages
2169 * for this case. Once we successfully lock a buffer the
2170 * only 0->1 transitions of b_refs will occur via findblk().
2172 * We must also check for queue changes after successful
2173 * locking as the current lock holder may dispose of the
2174 * buffer and change its queue.
2176 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT) != 0) {
2177 spin_unlock(&bufqspin);
2178 tsleep(&bd_request, 0, "gnbxxx", (hz + 99) / 100);
2181 if (bp->b_qindex != qindex || bp->b_refs) {
2182 spin_unlock(&bufqspin);
2186 bremfree_locked(bp);
2187 spin_unlock(&bufqspin);
2190 * Dependancies must be handled before we disassociate the
2193 * NOTE: HAMMER will set B_LOCKED if the buffer cannot
2194 * be immediately disassociated. HAMMER then becomes
2195 * responsible for releasing the buffer.
2197 * NOTE: bufqspin is UNLOCKED now.
2199 if (LIST_FIRST(&bp->b_dep) != NULL) {
2201 if (bp->b_flags & B_LOCKED) {
2205 KKASSERT(LIST_FIRST(&bp->b_dep) == NULL);
2208 if (qindex == BQUEUE_CLEAN) {
2209 if (bp->b_flags & B_VMIO)
2210 vfs_vmio_release(bp);
2216 * NOTE: nbp is now entirely invalid. We can only restart
2217 * the scan from this point on.
2219 * Get the rest of the buffer freed up. b_kva* is still
2220 * valid after this operation.
2222 KASSERT(bp->b_vp == NULL,
2223 ("bp3 %p flags %08x vnode %p qindex %d "
2224 "unexpectededly still associated!",
2225 bp, bp->b_flags, bp->b_vp, qindex));
2226 KKASSERT((bp->b_flags & B_HASHED) == 0);
2229 * critical section protection is not required when
2230 * scrapping a buffer's contents because it is already
2236 bp->b_flags = B_BNOCLIP;
2237 bp->b_cmd = BUF_CMD_DONE;
2242 bp->b_xio.xio_npages = 0;
2243 bp->b_dirtyoff = bp->b_dirtyend = 0;
2244 bp->b_act_count = ACT_INIT;
2246 KKASSERT(LIST_FIRST(&bp->b_dep) == NULL);
2248 if (blkflags & GETBLK_BHEAVY)
2249 bp->b_flags |= B_HEAVY;
2252 * If we are defragging then free the buffer.
2255 bp->b_flags |= B_INVAL;
2263 * If we are overcomitted then recover the buffer and its
2264 * KVM space. This occurs in rare situations when multiple
2265 * processes are blocked in getnewbuf() or allocbuf().
2267 if (bufspace >= hibufspace)
2269 if (flushingbufs && bp->b_kvasize != 0) {
2270 bp->b_flags |= B_INVAL;
2275 if (bufspace < lobufspace)
2279 * b_refs can transition to a non-zero value while we hold
2280 * the buffer locked due to a findblk(). Our brelvp() above
2281 * interlocked any future possible transitions due to
2284 * If we find b_refs to be non-zero we can destroy the
2285 * buffer's contents but we cannot yet reuse the buffer.
2288 bp->b_flags |= B_INVAL;
2294 /* NOT REACHED, bufqspin not held */
2298 * If we exhausted our list, sleep as appropriate. We may have to
2299 * wakeup various daemons and write out some dirty buffers.
2301 * Generally we are sleeping due to insufficient buffer space.
2303 * NOTE: bufqspin is held if bp is NULL, else it is not held.
2309 spin_unlock(&bufqspin);
2311 flags = VFS_BIO_NEED_BUFSPACE;
2313 } else if (bufspace >= hibufspace) {
2315 flags = VFS_BIO_NEED_BUFSPACE;
2318 flags = VFS_BIO_NEED_ANY;
2321 bd_speedup(); /* heeeelp */
2322 spin_lock(&bufcspin);
2323 needsbuffer |= flags;
2324 while (needsbuffer & flags) {
2325 if (ssleep(&needsbuffer, &bufcspin,
2326 slpflags, waitmsg, slptimeo)) {
2327 spin_unlock(&bufcspin);
2331 spin_unlock(&bufcspin);
2334 * We finally have a valid bp. We aren't quite out of the
2335 * woods, we still have to reserve kva space. In order
2336 * to keep fragmentation sane we only allocate kva in
2339 * (bufqspin is not held)
2341 maxsize = (maxsize + BKVAMASK) & ~BKVAMASK;
2343 if (maxsize != bp->b_kvasize) {
2344 vm_offset_t addr = 0;
2349 count = vm_map_entry_reserve(MAP_RESERVE_COUNT);
2350 vm_map_lock(&buffer_map);
2352 if (vm_map_findspace(&buffer_map,
2353 vm_map_min(&buffer_map), maxsize,
2354 maxsize, 0, &addr)) {
2356 * Uh oh. Buffer map is too fragmented. We
2357 * must defragment the map.
2359 vm_map_unlock(&buffer_map);
2360 vm_map_entry_release(count);
2363 bp->b_flags |= B_INVAL;
2368 vm_map_insert(&buffer_map, &count,
2370 addr, addr + maxsize,
2372 VM_PROT_ALL, VM_PROT_ALL,
2375 bp->b_kvabase = (caddr_t) addr;
2376 bp->b_kvasize = maxsize;
2377 bufspace += bp->b_kvasize;
2380 vm_map_unlock(&buffer_map);
2381 vm_map_entry_release(count);
2383 bp->b_data = bp->b_kvabase;
2389 * This routine is called in an emergency to recover VM pages from the
2390 * buffer cache by cashing in clean buffers. The idea is to recover
2391 * enough pages to be able to satisfy a stuck bio_page_alloc().
2396 recoverbufpages(void)
2403 spin_lock(&bufqspin);
2404 while (bytes < MAXBSIZE) {
2405 bp = TAILQ_FIRST(&bufqueues[BQUEUE_CLEAN]);
2410 * BQUEUE_CLEAN - B_AGE special case. If not set the bp
2411 * cycles through the queue twice before being selected.
2413 if ((bp->b_flags & B_AGE) == 0 && TAILQ_NEXT(bp, b_freelist)) {
2414 bp->b_flags |= B_AGE;
2415 TAILQ_REMOVE(&bufqueues[BQUEUE_CLEAN], bp, b_freelist);
2416 TAILQ_INSERT_TAIL(&bufqueues[BQUEUE_CLEAN],
2424 KKASSERT(bp->b_qindex == BQUEUE_CLEAN);
2425 KKASSERT((bp->b_flags & B_DELWRI) == 0);
2428 * Start freeing the bp. This is somewhat involved.
2430 * Buffers on the clean list must be disassociated from
2431 * their current vnode
2434 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT) != 0) {
2435 kprintf("recoverbufpages: warning, locked buf %p, "
2438 ssleep(&bd_request, &bufqspin, 0, "gnbxxx", hz / 100);
2441 if (bp->b_qindex != BQUEUE_CLEAN) {
2442 kprintf("recoverbufpages: warning, BUF_LOCK blocked "
2443 "unexpectedly on buf %p index %d, race "
2449 bremfree_locked(bp);
2450 spin_unlock(&bufqspin);
2453 * Dependancies must be handled before we disassociate the
2456 * NOTE: HAMMER will set B_LOCKED if the buffer cannot
2457 * be immediately disassociated. HAMMER then becomes
2458 * responsible for releasing the buffer.
2460 if (LIST_FIRST(&bp->b_dep) != NULL) {
2462 if (bp->b_flags & B_LOCKED) {
2464 spin_lock(&bufqspin);
2467 KKASSERT(LIST_FIRST(&bp->b_dep) == NULL);
2470 bytes += bp->b_bufsize;
2472 if (bp->b_flags & B_VMIO) {
2473 bp->b_flags |= B_DIRECT; /* try to free pages */
2474 vfs_vmio_release(bp);
2479 KKASSERT(bp->b_vp == NULL);
2480 KKASSERT((bp->b_flags & B_HASHED) == 0);
2483 * critical section protection is not required when
2484 * scrapping a buffer's contents because it is already
2490 bp->b_flags = B_BNOCLIP;
2491 bp->b_cmd = BUF_CMD_DONE;
2496 bp->b_xio.xio_npages = 0;
2497 bp->b_dirtyoff = bp->b_dirtyend = 0;
2499 KKASSERT(LIST_FIRST(&bp->b_dep) == NULL);
2501 bp->b_flags |= B_INVAL;
2504 spin_lock(&bufqspin);
2506 spin_unlock(&bufqspin);
2513 * Buffer flushing daemon. Buffers are normally flushed by the
2514 * update daemon but if it cannot keep up this process starts to
2515 * take the load in an attempt to prevent getnewbuf() from blocking.
2517 * Once a flush is initiated it does not stop until the number
2518 * of buffers falls below lodirtybuffers, but we will wake up anyone
2519 * waiting at the mid-point.
2522 static struct kproc_desc buf_kp = {
2527 SYSINIT(bufdaemon, SI_SUB_KTHREAD_BUF, SI_ORDER_FIRST,
2528 kproc_start, &buf_kp)
2530 static struct kproc_desc bufhw_kp = {
2535 SYSINIT(bufdaemon_hw, SI_SUB_KTHREAD_BUF, SI_ORDER_FIRST,
2536 kproc_start, &bufhw_kp)
2547 * This process needs to be suspended prior to shutdown sync.
2549 EVENTHANDLER_REGISTER(shutdown_pre_sync, shutdown_kproc,
2550 bufdaemon_td, SHUTDOWN_PRI_LAST);
2551 curthread->td_flags |= TDF_SYSTHREAD;
2554 * This process is allowed to take the buffer cache to the limit
2557 kproc_suspend_loop();
2560 * Do the flush as long as the number of dirty buffers
2561 * (including those running) exceeds lodirtybufspace.
2563 * When flushing limit running I/O to hirunningspace
2564 * Do the flush. Limit the amount of in-transit I/O we
2565 * allow to build up, otherwise we would completely saturate
2566 * the I/O system. Wakeup any waiting processes before we
2567 * normally would so they can run in parallel with our drain.
2569 * Our aggregate normal+HW lo water mark is lodirtybufspace,
2570 * but because we split the operation into two threads we
2571 * have to cut it in half for each thread.
2573 waitrunningbufspace();
2574 limit = lodirtybufspace / 2;
2575 while (runningbufspace + dirtybufspace > limit ||
2576 dirtybufcount - dirtybufcounthw >= nbuf / 2) {
2577 if (flushbufqueues(BQUEUE_DIRTY) == 0)
2579 if (runningbufspace < hirunningspace)
2581 waitrunningbufspace();
2585 * We reached our low water mark, reset the
2586 * request and sleep until we are needed again.
2587 * The sleep is just so the suspend code works.
2589 spin_lock(&bufcspin);
2590 if (bd_request == 0)
2591 ssleep(&bd_request, &bufcspin, 0, "psleep", hz);
2593 spin_unlock(&bufcspin);
2606 * This process needs to be suspended prior to shutdown sync.
2608 EVENTHANDLER_REGISTER(shutdown_pre_sync, shutdown_kproc,
2609 bufdaemonhw_td, SHUTDOWN_PRI_LAST);
2610 curthread->td_flags |= TDF_SYSTHREAD;
2613 * This process is allowed to take the buffer cache to the limit
2616 kproc_suspend_loop();
2619 * Do the flush. Limit the amount of in-transit I/O we
2620 * allow to build up, otherwise we would completely saturate
2621 * the I/O system. Wakeup any waiting processes before we
2622 * normally would so they can run in parallel with our drain.
2624 * Once we decide to flush push the queued I/O up to
2625 * hirunningspace in order to trigger bursting by the bioq
2628 * Our aggregate normal+HW lo water mark is lodirtybufspace,
2629 * but because we split the operation into two threads we
2630 * have to cut it in half for each thread.
2632 waitrunningbufspace();
2633 limit = lodirtybufspace / 2;
2634 while (runningbufspace + dirtybufspacehw > limit ||
2635 dirtybufcounthw >= nbuf / 2) {
2636 if (flushbufqueues(BQUEUE_DIRTY_HW) == 0)
2638 if (runningbufspace < hirunningspace)
2640 waitrunningbufspace();
2644 * We reached our low water mark, reset the
2645 * request and sleep until we are needed again.
2646 * The sleep is just so the suspend code works.
2648 spin_lock(&bufcspin);
2649 if (bd_request_hw == 0)
2650 ssleep(&bd_request_hw, &bufcspin, 0, "psleep", hz);
2652 spin_unlock(&bufcspin);
2659 * Try to flush a buffer in the dirty queue. We must be careful to
2660 * free up B_INVAL buffers instead of write them, which NFS is
2661 * particularly sensitive to.
2663 * B_RELBUF may only be set by VFSs. We do set B_AGE to indicate
2664 * that we really want to try to get the buffer out and reuse it
2665 * due to the write load on the machine.
2667 * We must lock the buffer in order to check its validity before we
2668 * can mess with its contents. bufqspin isn't enough.
2671 flushbufqueues(bufq_type_t q)
2677 spin_lock(&bufqspin);
2680 bp = TAILQ_FIRST(&bufqueues[q]);
2682 if ((bp->b_flags & B_DELWRI) == 0) {
2683 kprintf("Unexpected clean buffer %p\n", bp);
2684 bp = TAILQ_NEXT(bp, b_freelist);
2687 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT)) {
2688 bp = TAILQ_NEXT(bp, b_freelist);
2691 KKASSERT(bp->b_qindex == q);
2694 * Must recheck B_DELWRI after successfully locking
2697 if ((bp->b_flags & B_DELWRI) == 0) {
2699 bp = TAILQ_NEXT(bp, b_freelist);
2703 if (bp->b_flags & B_INVAL) {
2705 spin_unlock(&bufqspin);
2712 spin_unlock(&bufqspin);
2715 if (LIST_FIRST(&bp->b_dep) != NULL &&
2716 (bp->b_flags & B_DEFERRED) == 0 &&
2717 buf_countdeps(bp, 0)) {
2718 spin_lock(&bufqspin);
2720 TAILQ_REMOVE(&bufqueues[q], bp, b_freelist);
2721 TAILQ_INSERT_TAIL(&bufqueues[q], bp, b_freelist);
2722 bp->b_flags |= B_DEFERRED;
2724 bp = TAILQ_FIRST(&bufqueues[q]);
2729 * If the buffer has a dependancy, buf_checkwrite() must
2730 * also return 0 for us to be able to initate the write.
2732 * If the buffer is flagged B_ERROR it may be requeued
2733 * over and over again, we try to avoid a live lock.
2735 * NOTE: buf_checkwrite is MPSAFE.
2737 if (LIST_FIRST(&bp->b_dep) != NULL && buf_checkwrite(bp)) {
2740 } else if (bp->b_flags & B_ERROR) {
2741 tsleep(bp, 0, "bioer", 1);
2742 bp->b_flags &= ~B_AGE;
2745 bp->b_flags |= B_AGE;
2752 spin_unlock(&bufqspin);
2759 * Returns true if no I/O is needed to access the associated VM object.
2760 * This is like findblk except it also hunts around in the VM system for
2763 * Note that we ignore vm_page_free() races from interrupts against our
2764 * lookup, since if the caller is not protected our return value will not
2765 * be any more valid then otherwise once we exit the critical section.
2768 inmem(struct vnode *vp, off_t loffset)
2771 vm_offset_t toff, tinc, size;
2774 if (findblk(vp, loffset, FINDBLK_TEST))
2776 if (vp->v_mount == NULL)
2778 if ((obj = vp->v_object) == NULL)
2782 if (size > vp->v_mount->mnt_stat.f_iosize)
2783 size = vp->v_mount->mnt_stat.f_iosize;
2785 for (toff = 0; toff < vp->v_mount->mnt_stat.f_iosize; toff += tinc) {
2786 lwkt_gettoken(&vm_token);
2787 m = vm_page_lookup(obj, OFF_TO_IDX(loffset + toff));
2788 lwkt_reltoken(&vm_token);
2792 if (tinc > PAGE_SIZE - ((toff + loffset) & PAGE_MASK))
2793 tinc = PAGE_SIZE - ((toff + loffset) & PAGE_MASK);
2794 if (vm_page_is_valid(m,
2795 (vm_offset_t) ((toff + loffset) & PAGE_MASK), tinc) == 0)
2804 * Locate and return the specified buffer. Unless flagged otherwise,
2805 * a locked buffer will be returned if it exists or NULL if it does not.
2807 * findblk()'d buffers are still on the bufqueues and if you intend
2808 * to use your (locked NON-TEST) buffer you need to bremfree(bp)
2809 * and possibly do other stuff to it.
2811 * FINDBLK_TEST - Do not lock the buffer. The caller is responsible
2812 * for locking the buffer and ensuring that it remains
2813 * the desired buffer after locking.
2815 * FINDBLK_NBLOCK - Lock the buffer non-blocking. If we are unable
2816 * to acquire the lock we return NULL, even if the
2819 * FINDBLK_REF - Returns the buffer ref'd, which prevents normal
2820 * reuse by getnewbuf() but does not prevent
2821 * disassociation (B_INVAL). Used to avoid deadlocks
2822 * against random (vp,loffset)s due to reassignment.
2824 * (0) - Lock the buffer blocking.
2829 findblk(struct vnode *vp, off_t loffset, int flags)
2834 lkflags = LK_EXCLUSIVE;
2835 if (flags & FINDBLK_NBLOCK)
2836 lkflags |= LK_NOWAIT;
2840 * Lookup. Ref the buf while holding v_token to prevent
2841 * reuse (but does not prevent diassociation).
2843 lwkt_gettoken(&vp->v_token);
2844 bp = buf_rb_hash_RB_LOOKUP(&vp->v_rbhash_tree, loffset);
2846 lwkt_reltoken(&vp->v_token);
2850 lwkt_reltoken(&vp->v_token);
2853 * If testing only break and return bp, do not lock.
2855 if (flags & FINDBLK_TEST)
2859 * Lock the buffer, return an error if the lock fails.
2860 * (only FINDBLK_NBLOCK can cause the lock to fail).
2862 if (BUF_LOCK(bp, lkflags)) {
2863 atomic_subtract_int(&bp->b_refs, 1);
2864 /* bp = NULL; not needed */
2869 * Revalidate the locked buf before allowing it to be
2872 if (bp->b_vp == vp && bp->b_loffset == loffset)
2874 atomic_subtract_int(&bp->b_refs, 1);
2881 if ((flags & FINDBLK_REF) == 0)
2882 atomic_subtract_int(&bp->b_refs, 1);
2889 * Similar to getblk() except only returns the buffer if it is
2890 * B_CACHE and requires no other manipulation. Otherwise NULL
2893 * If B_RAM is set the buffer might be just fine, but we return
2894 * NULL anyway because we want the code to fall through to the
2895 * cluster read. Otherwise read-ahead breaks.
2897 * If blksize is 0 the buffer cache buffer must already be fully
2900 * If blksize is non-zero getblk() will be used, allowing a buffer
2901 * to be reinstantiated from its VM backing store. The buffer must
2902 * still be fully cached after reinstantiation to be returned.
2905 getcacheblk(struct vnode *vp, off_t loffset, int blksize)
2910 bp = getblk(vp, loffset, blksize, 0, 0);
2912 if ((bp->b_flags & (B_INVAL | B_CACHE | B_RAM)) ==
2914 bp->b_flags &= ~B_AGE;
2921 bp = findblk(vp, loffset, 0);
2923 if ((bp->b_flags & (B_INVAL | B_CACHE | B_RAM)) ==
2925 bp->b_flags &= ~B_AGE;
2939 * Get a block given a specified block and offset into a file/device.
2940 * B_INVAL may or may not be set on return. The caller should clear
2941 * B_INVAL prior to initiating a READ.
2943 * IT IS IMPORTANT TO UNDERSTAND THAT IF YOU CALL GETBLK() AND B_CACHE
2944 * IS NOT SET, YOU MUST INITIALIZE THE RETURNED BUFFER, ISSUE A READ,
2945 * OR SET B_INVAL BEFORE RETIRING IT. If you retire a getblk'd buffer
2946 * without doing any of those things the system will likely believe
2947 * the buffer to be valid (especially if it is not B_VMIO), and the
2948 * next getblk() will return the buffer with B_CACHE set.
2950 * For a non-VMIO buffer, B_CACHE is set to the opposite of B_INVAL for
2951 * an existing buffer.
2953 * For a VMIO buffer, B_CACHE is modified according to the backing VM.
2954 * If getblk()ing a previously 0-sized invalid buffer, B_CACHE is set
2955 * and then cleared based on the backing VM. If the previous buffer is
2956 * non-0-sized but invalid, B_CACHE will be cleared.
2958 * If getblk() must create a new buffer, the new buffer is returned with
2959 * both B_INVAL and B_CACHE clear unless it is a VMIO buffer, in which
2960 * case it is returned with B_INVAL clear and B_CACHE set based on the
2963 * getblk() also forces a bwrite() for any B_DELWRI buffer whos
2964 * B_CACHE bit is clear.
2966 * What this means, basically, is that the caller should use B_CACHE to
2967 * determine whether the buffer is fully valid or not and should clear
2968 * B_INVAL prior to issuing a read. If the caller intends to validate
2969 * the buffer by loading its data area with something, the caller needs
2970 * to clear B_INVAL. If the caller does this without issuing an I/O,
2971 * the caller should set B_CACHE ( as an optimization ), else the caller
2972 * should issue the I/O and biodone() will set B_CACHE if the I/O was
2973 * a write attempt or if it was a successfull read. If the caller
2974 * intends to issue a READ, the caller must clear B_INVAL and B_ERROR
2975 * prior to issuing the READ. biodone() will *not* clear B_INVAL.
2979 * GETBLK_PCATCH - catch signal if blocked, can cause NULL return
2980 * GETBLK_BHEAVY - heavy-weight buffer cache buffer
2985 getblk(struct vnode *vp, off_t loffset, int size, int blkflags, int slptimeo)
2988 int slpflags = (blkflags & GETBLK_PCATCH) ? PCATCH : 0;
2992 if (size > MAXBSIZE)
2993 panic("getblk: size(%d) > MAXBSIZE(%d)", size, MAXBSIZE);
2994 if (vp->v_object == NULL)
2995 panic("getblk: vnode %p has no object!", vp);
2998 if ((bp = findblk(vp, loffset, FINDBLK_REF | FINDBLK_TEST)) != NULL) {
3000 * The buffer was found in the cache, but we need to lock it.
3001 * We must acquire a ref on the bp to prevent reuse, but
3002 * this will not prevent disassociation (brelvp()) so we
3003 * must recheck (vp,loffset) after acquiring the lock.
3005 * Without the ref the buffer could potentially be reused
3006 * before we acquire the lock and create a deadlock
3007 * situation between the thread trying to reuse the buffer
3008 * and us due to the fact that we would wind up blocking
3009 * on a random (vp,loffset).
3011 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT)) {
3012 if (blkflags & GETBLK_NOWAIT) {
3016 lkflags = LK_EXCLUSIVE | LK_SLEEPFAIL;
3017 if (blkflags & GETBLK_PCATCH)
3018 lkflags |= LK_PCATCH;
3019 error = BUF_TIMELOCK(bp, lkflags, "getblk", slptimeo);
3022 if (error == ENOLCK)
3026 /* buffer may have changed on us */
3031 * Once the buffer has been locked, make sure we didn't race
3032 * a buffer recyclement. Buffers that are no longer hashed
3033 * will have b_vp == NULL, so this takes care of that check
3036 if (bp->b_vp != vp || bp->b_loffset != loffset) {
3037 kprintf("Warning buffer %p (vp %p loffset %lld) "
3039 bp, vp, (long long)loffset);
3045 * If SZMATCH any pre-existing buffer must be of the requested
3046 * size or NULL is returned. The caller absolutely does not
3047 * want getblk() to bwrite() the buffer on a size mismatch.
3049 if ((blkflags & GETBLK_SZMATCH) && size != bp->b_bcount) {
3055 * All vnode-based buffers must be backed by a VM object.
3057 KKASSERT(bp->b_flags & B_VMIO);
3058 KKASSERT(bp->b_cmd == BUF_CMD_DONE);
3059 bp->b_flags &= ~B_AGE;
3062 * Make sure that B_INVAL buffers do not have a cached
3063 * block number translation.
3065 if ((bp->b_flags & B_INVAL) && (bp->b_bio2.bio_offset != NOOFFSET)) {
3066 kprintf("Warning invalid buffer %p (vp %p loffset %lld)"
3067 " did not have cleared bio_offset cache\n",
3068 bp, vp, (long long)loffset);
3069 clearbiocache(&bp->b_bio2);
3073 * The buffer is locked. B_CACHE is cleared if the buffer is
3076 if (bp->b_flags & B_INVAL)
3077 bp->b_flags &= ~B_CACHE;
3081 * Any size inconsistancy with a dirty buffer or a buffer
3082 * with a softupdates dependancy must be resolved. Resizing
3083 * the buffer in such circumstances can lead to problems.
3085 * Dirty or dependant buffers are written synchronously.
3086 * Other types of buffers are simply released and
3087 * reconstituted as they may be backed by valid, dirty VM
3088 * pages (but not marked B_DELWRI).
3090 * NFS NOTE: NFS buffers which straddle EOF are oddly-sized
3091 * and may be left over from a prior truncation (and thus
3092 * no longer represent the actual EOF point), so we
3093 * definitely do not want to B_NOCACHE the backing store.
3095 if (size != bp->b_bcount) {
3096 if (bp->b_flags & B_DELWRI) {
3097 bp->b_flags |= B_RELBUF;
3099 } else if (LIST_FIRST(&bp->b_dep)) {
3100 bp->b_flags |= B_RELBUF;
3103 bp->b_flags |= B_RELBUF;
3108 KKASSERT(size <= bp->b_kvasize);
3109 KASSERT(bp->b_loffset != NOOFFSET,
3110 ("getblk: no buffer offset"));
3113 * A buffer with B_DELWRI set and B_CACHE clear must
3114 * be committed before we can return the buffer in
3115 * order to prevent the caller from issuing a read
3116 * ( due to B_CACHE not being set ) and overwriting
3119 * Most callers, including NFS and FFS, need this to
3120 * operate properly either because they assume they
3121 * can issue a read if B_CACHE is not set, or because
3122 * ( for example ) an uncached B_DELWRI might loop due
3123 * to softupdates re-dirtying the buffer. In the latter
3124 * case, B_CACHE is set after the first write completes,
3125 * preventing further loops.
3127 * NOTE! b*write() sets B_CACHE. If we cleared B_CACHE
3128 * above while extending the buffer, we cannot allow the
3129 * buffer to remain with B_CACHE set after the write
3130 * completes or it will represent a corrupt state. To
3131 * deal with this we set B_NOCACHE to scrap the buffer
3134 * XXX Should this be B_RELBUF instead of B_NOCACHE?
3135 * I'm not even sure this state is still possible
3136 * now that getblk() writes out any dirty buffers
3139 * We might be able to do something fancy, like setting
3140 * B_CACHE in bwrite() except if B_DELWRI is already set,
3141 * so the below call doesn't set B_CACHE, but that gets real
3142 * confusing. This is much easier.
3145 if ((bp->b_flags & (B_CACHE|B_DELWRI)) == B_DELWRI) {
3146 kprintf("getblk: Warning, bp %p loff=%jx DELWRI set "
3147 "and CACHE clear, b_flags %08x\n",
3148 bp, (intmax_t)bp->b_loffset, bp->b_flags);
3149 bp->b_flags |= B_NOCACHE;
3155 * Buffer is not in-core, create new buffer. The buffer
3156 * returned by getnewbuf() is locked. Note that the returned
3157 * buffer is also considered valid (not marked B_INVAL).
3159 * Calculating the offset for the I/O requires figuring out
3160 * the block size. We use DEV_BSIZE for VBLK or VCHR and
3161 * the mount's f_iosize otherwise. If the vnode does not
3162 * have an associated mount we assume that the passed size is
3165 * Note that vn_isdisk() cannot be used here since it may
3166 * return a failure for numerous reasons. Note that the
3167 * buffer size may be larger then the block size (the caller
3168 * will use block numbers with the proper multiple). Beware
3169 * of using any v_* fields which are part of unions. In
3170 * particular, in DragonFly the mount point overloading
3171 * mechanism uses the namecache only and the underlying
3172 * directory vnode is not a special case.
3176 if (vp->v_type == VBLK || vp->v_type == VCHR)
3178 else if (vp->v_mount)
3179 bsize = vp->v_mount->mnt_stat.f_iosize;
3183 maxsize = size + (loffset & PAGE_MASK);
3184 maxsize = imax(maxsize, bsize);
3186 bp = getnewbuf(blkflags, slptimeo, size, maxsize);
3188 if (slpflags || slptimeo)
3194 * Atomically insert the buffer into the hash, so that it can
3195 * be found by findblk().
3197 * If bgetvp() returns non-zero a collision occured, and the
3198 * bp will not be associated with the vnode.
3200 * Make sure the translation layer has been cleared.
3202 bp->b_loffset = loffset;
3203 bp->b_bio2.bio_offset = NOOFFSET;
3204 /* bp->b_bio2.bio_next = NULL; */
3206 if (bgetvp(vp, bp, size)) {
3207 bp->b_flags |= B_INVAL;
3213 * All vnode-based buffers must be backed by a VM object.
3215 KKASSERT(vp->v_object != NULL);
3216 bp->b_flags |= B_VMIO;
3217 KKASSERT(bp->b_cmd == BUF_CMD_DONE);
3221 KKASSERT(dsched_is_clear_buf_priv(bp));
3228 * Reacquire a buffer that was previously released to the locked queue,
3229 * or reacquire a buffer which is interlocked by having bioops->io_deallocate
3230 * set B_LOCKED (which handles the acquisition race).
3232 * To this end, either B_LOCKED must be set or the dependancy list must be
3238 regetblk(struct buf *bp)
3240 KKASSERT((bp->b_flags & B_LOCKED) || LIST_FIRST(&bp->b_dep) != NULL);
3241 BUF_LOCK(bp, LK_EXCLUSIVE | LK_RETRY);
3248 * Get an empty, disassociated buffer of given size. The buffer is
3249 * initially set to B_INVAL.
3251 * critical section protection is not required for the allocbuf()
3252 * call because races are impossible here.
3262 maxsize = (size + BKVAMASK) & ~BKVAMASK;
3264 while ((bp = getnewbuf(0, 0, size, maxsize)) == 0)
3267 bp->b_flags |= B_INVAL; /* b_dep cleared by getnewbuf() */
3268 KKASSERT(dsched_is_clear_buf_priv(bp));
3276 * This code constitutes the buffer memory from either anonymous system
3277 * memory (in the case of non-VMIO operations) or from an associated
3278 * VM object (in the case of VMIO operations). This code is able to
3279 * resize a buffer up or down.
3281 * Note that this code is tricky, and has many complications to resolve
3282 * deadlock or inconsistant data situations. Tread lightly!!!
3283 * There are B_CACHE and B_DELWRI interactions that must be dealt with by
3284 * the caller. Calling this code willy nilly can result in the loss of
3287 * allocbuf() only adjusts B_CACHE for VMIO buffers. getblk() deals with
3288 * B_CACHE for the non-VMIO case.
3290 * This routine does not need to be called from a critical section but you
3291 * must own the buffer.
3296 allocbuf(struct buf *bp, int size)
3298 int newbsize, mbsize;
3301 if (BUF_REFCNT(bp) == 0)
3302 panic("allocbuf: buffer not busy");
3304 if (bp->b_kvasize < size)
3305 panic("allocbuf: buffer too small");
3307 if ((bp->b_flags & B_VMIO) == 0) {
3311 * Just get anonymous memory from the kernel. Don't
3312 * mess with B_CACHE.
3314 mbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1);
3315 if (bp->b_flags & B_MALLOC)
3318 newbsize = round_page(size);
3320 if (newbsize < bp->b_bufsize) {
3322 * Malloced buffers are not shrunk
3324 if (bp->b_flags & B_MALLOC) {
3326 bp->b_bcount = size;
3328 kfree(bp->b_data, M_BIOBUF);
3329 if (bp->b_bufsize) {
3330 atomic_subtract_int(&bufmallocspace, bp->b_bufsize);
3334 bp->b_data = bp->b_kvabase;
3336 bp->b_flags &= ~B_MALLOC;
3342 (vm_offset_t) bp->b_data + newbsize,
3343 (vm_offset_t) bp->b_data + bp->b_bufsize);
3344 } else if (newbsize > bp->b_bufsize) {
3346 * We only use malloced memory on the first allocation.
3347 * and revert to page-allocated memory when the buffer
3350 if ((bufmallocspace < maxbufmallocspace) &&
3351 (bp->b_bufsize == 0) &&
3352 (mbsize <= PAGE_SIZE/2)) {
3354 bp->b_data = kmalloc(mbsize, M_BIOBUF, M_WAITOK);
3355 bp->b_bufsize = mbsize;
3356 bp->b_bcount = size;
3357 bp->b_flags |= B_MALLOC;
3358 atomic_add_int(&bufmallocspace, mbsize);
3364 * If the buffer is growing on its other-than-first
3365 * allocation, then we revert to the page-allocation
3368 if (bp->b_flags & B_MALLOC) {
3369 origbuf = bp->b_data;
3370 origbufsize = bp->b_bufsize;
3371 bp->b_data = bp->b_kvabase;
3372 if (bp->b_bufsize) {
3373 atomic_subtract_int(&bufmallocspace,
3378 bp->b_flags &= ~B_MALLOC;
3379 newbsize = round_page(newbsize);
3383 (vm_offset_t) bp->b_data + bp->b_bufsize,
3384 (vm_offset_t) bp->b_data + newbsize);
3386 bcopy(origbuf, bp->b_data, origbufsize);
3387 kfree(origbuf, M_BIOBUF);
3394 newbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1);
3395 desiredpages = ((int)(bp->b_loffset & PAGE_MASK) +
3396 newbsize + PAGE_MASK) >> PAGE_SHIFT;
3397 KKASSERT(desiredpages <= XIO_INTERNAL_PAGES);
3399 if (bp->b_flags & B_MALLOC)
3400 panic("allocbuf: VMIO buffer can't be malloced");
3402 * Set B_CACHE initially if buffer is 0 length or will become
3405 if (size == 0 || bp->b_bufsize == 0)
3406 bp->b_flags |= B_CACHE;
3408 if (newbsize < bp->b_bufsize) {
3410 * DEV_BSIZE aligned new buffer size is less then the
3411 * DEV_BSIZE aligned existing buffer size. Figure out
3412 * if we have to remove any pages.
3414 if (desiredpages < bp->b_xio.xio_npages) {
3415 for (i = desiredpages; i < bp->b_xio.xio_npages; i++) {
3417 * the page is not freed here -- it
3418 * is the responsibility of
3419 * vnode_pager_setsize
3421 m = bp->b_xio.xio_pages[i];
3422 KASSERT(m != bogus_page,
3423 ("allocbuf: bogus page found"));
3424 while (vm_page_sleep_busy(m, TRUE, "biodep"))
3427 bp->b_xio.xio_pages[i] = NULL;
3428 vm_page_unwire(m, 0);
3430 pmap_qremove((vm_offset_t) trunc_page((vm_offset_t)bp->b_data) +
3431 (desiredpages << PAGE_SHIFT), (bp->b_xio.xio_npages - desiredpages));
3432 bp->b_xio.xio_npages = desiredpages;
3434 } else if (size > bp->b_bcount) {
3436 * We are growing the buffer, possibly in a
3437 * byte-granular fashion.
3445 * Step 1, bring in the VM pages from the object,
3446 * allocating them if necessary. We must clear
3447 * B_CACHE if these pages are not valid for the
3448 * range covered by the buffer.
3450 * critical section protection is required to protect
3451 * against interrupts unbusying and freeing pages
3452 * between our vm_page_lookup() and our
3453 * busycheck/wiring call.
3458 lwkt_gettoken(&vm_token);
3459 while (bp->b_xio.xio_npages < desiredpages) {
3463 pi = OFF_TO_IDX(bp->b_loffset) + bp->b_xio.xio_npages;
3464 if ((m = vm_page_lookup(obj, pi)) == NULL) {
3466 * note: must allocate system pages
3467 * since blocking here could intefere
3468 * with paging I/O, no matter which
3471 m = bio_page_alloc(obj, pi, desiredpages - bp->b_xio.xio_npages);
3474 vm_page_flag_clear(m, PG_ZERO);
3476 bp->b_flags &= ~B_CACHE;
3477 bp->b_xio.xio_pages[bp->b_xio.xio_npages] = m;
3478 ++bp->b_xio.xio_npages;
3484 * We found a page. If we have to sleep on it,
3485 * retry because it might have gotten freed out
3488 * We can only test PG_BUSY here. Blocking on
3489 * m->busy might lead to a deadlock:
3491 * vm_fault->getpages->cluster_read->allocbuf
3495 if (vm_page_sleep_busy(m, FALSE, "pgtblk"))
3497 vm_page_flag_clear(m, PG_ZERO);
3499 bp->b_xio.xio_pages[bp->b_xio.xio_npages] = m;
3500 ++bp->b_xio.xio_npages;
3501 if (bp->b_act_count < m->act_count)
3502 bp->b_act_count = m->act_count;
3504 lwkt_reltoken(&vm_token);
3507 * Step 2. We've loaded the pages into the buffer,
3508 * we have to figure out if we can still have B_CACHE
3509 * set. Note that B_CACHE is set according to the
3510 * byte-granular range ( bcount and size ), not the
3511 * aligned range ( newbsize ).
3513 * The VM test is against m->valid, which is DEV_BSIZE
3514 * aligned. Needless to say, the validity of the data
3515 * needs to also be DEV_BSIZE aligned. Note that this
3516 * fails with NFS if the server or some other client
3517 * extends the file's EOF. If our buffer is resized,
3518 * B_CACHE may remain set! XXX
3521 toff = bp->b_bcount;
3522 tinc = PAGE_SIZE - ((bp->b_loffset + toff) & PAGE_MASK);
3524 while ((bp->b_flags & B_CACHE) && toff < size) {
3527 if (tinc > (size - toff))
3530 pi = ((bp->b_loffset & PAGE_MASK) + toff) >>
3538 bp->b_xio.xio_pages[pi]
3545 * Step 3, fixup the KVM pmap. Remember that
3546 * bp->b_data is relative to bp->b_loffset, but
3547 * bp->b_loffset may be offset into the first page.
3550 bp->b_data = (caddr_t)
3551 trunc_page((vm_offset_t)bp->b_data);
3553 (vm_offset_t)bp->b_data,
3554 bp->b_xio.xio_pages,
3555 bp->b_xio.xio_npages
3557 bp->b_data = (caddr_t)((vm_offset_t)bp->b_data |
3558 (vm_offset_t)(bp->b_loffset & PAGE_MASK));
3562 /* adjust space use on already-dirty buffer */
3563 if (bp->b_flags & B_DELWRI) {
3564 spin_lock(&bufcspin);
3565 dirtybufspace += newbsize - bp->b_bufsize;
3566 if (bp->b_flags & B_HEAVY)
3567 dirtybufspacehw += newbsize - bp->b_bufsize;
3568 spin_unlock(&bufcspin);
3570 if (newbsize < bp->b_bufsize)
3572 bp->b_bufsize = newbsize; /* actual buffer allocation */
3573 bp->b_bcount = size; /* requested buffer size */
3580 * Wait for buffer I/O completion, returning error status. B_EINTR
3581 * is converted into an EINTR error but not cleared (since a chain
3582 * of biowait() calls may occur).
3584 * On return bpdone() will have been called but the buffer will remain
3585 * locked and will not have been brelse()'d.
3587 * NOTE! If a timeout is specified and ETIMEDOUT occurs the I/O is
3588 * likely still in progress on return.
3590 * NOTE! This operation is on a BIO, not a BUF.
3592 * NOTE! BIO_DONE is cleared by vn_strategy()
3597 _biowait(struct bio *bio, const char *wmesg, int to)
3599 struct buf *bp = bio->bio_buf;
3604 KKASSERT(bio == &bp->b_bio1);
3606 flags = bio->bio_flags;
3607 if (flags & BIO_DONE)
3609 nflags = flags | BIO_WANT;
3610 tsleep_interlock(bio, 0);
3611 if (atomic_cmpset_int(&bio->bio_flags, flags, nflags)) {
3613 error = tsleep(bio, PINTERLOCKED, wmesg, to);
3614 else if (bp->b_cmd == BUF_CMD_READ)
3615 error = tsleep(bio, PINTERLOCKED, "biord", to);
3617 error = tsleep(bio, PINTERLOCKED, "biowr", to);
3619 kprintf("tsleep error biowait %d\n", error);
3628 KKASSERT(bp->b_cmd == BUF_CMD_DONE);
3629 bio->bio_flags &= ~(BIO_DONE | BIO_SYNC);
3630 if (bp->b_flags & B_EINTR)
3632 if (bp->b_flags & B_ERROR)
3633 return (bp->b_error ? bp->b_error : EIO);
3638 biowait(struct bio *bio, const char *wmesg)
3640 return(_biowait(bio, wmesg, 0));
3644 biowait_timeout(struct bio *bio, const char *wmesg, int to)
3646 return(_biowait(bio, wmesg, to));
3650 * This associates a tracking count with an I/O. vn_strategy() and
3651 * dev_dstrategy() do this automatically but there are a few cases
3652 * where a vnode or device layer is bypassed when a block translation
3653 * is cached. In such cases bio_start_transaction() may be called on
3654 * the bypassed layers so the system gets an I/O in progress indication
3655 * for those higher layers.
3658 bio_start_transaction(struct bio *bio, struct bio_track *track)
3660 bio->bio_track = track;
3661 if (dsched_is_clear_buf_priv(bio->bio_buf))
3662 dsched_new_buf(bio->bio_buf);
3663 bio_track_ref(track);
3667 * Initiate I/O on a vnode.
3669 * SWAPCACHE OPERATION:
3671 * Real buffer cache buffers have a non-NULL bp->b_vp. Unfortunately
3672 * devfs also uses b_vp for fake buffers so we also have to check
3673 * that B_PAGING is 0. In this case the passed 'vp' is probably the
3674 * underlying block device. The swap assignments are related to the
3675 * buffer cache buffer's b_vp, not the passed vp.
3677 * The passed vp == bp->b_vp only in the case where the strategy call
3678 * is made on the vp itself for its own buffers (a regular file or
3679 * block device vp). The filesystem usually then re-calls vn_strategy()
3680 * after translating the request to an underlying device.
3682 * Cluster buffers set B_CLUSTER and the passed vp is the vp of the
3683 * underlying buffer cache buffers.
3685 * We can only deal with page-aligned buffers at the moment, because
3686 * we can't tell what the real dirty state for pages straddling a buffer
3689 * In order to call swap_pager_strategy() we must provide the VM object
3690 * and base offset for the underlying buffer cache pages so it can find
3694 vn_strategy(struct vnode *vp, struct bio *bio)
3696 struct bio_track *track;
3697 struct buf *bp = bio->bio_buf;
3699 KKASSERT(bp->b_cmd != BUF_CMD_DONE);
3702 * Set when an I/O is issued on the bp. Cleared by consumers
3703 * (aka HAMMER), allowing the consumer to determine if I/O had
3704 * actually occurred.
3706 bp->b_flags |= B_IODEBUG;
3709 * Handle the swap cache intercept.
3711 if (vn_cache_strategy(vp, bio))
3715 * Otherwise do the operation through the filesystem
3717 if (bp->b_cmd == BUF_CMD_READ)
3718 track = &vp->v_track_read;
3720 track = &vp->v_track_write;
3721 KKASSERT((bio->bio_flags & BIO_DONE) == 0);
3722 bio->bio_track = track;
3723 if (dsched_is_clear_buf_priv(bio->bio_buf))
3724 dsched_new_buf(bio->bio_buf);
3725 bio_track_ref(track);
3726 vop_strategy(*vp->v_ops, vp, bio);
3729 static void vn_cache_strategy_callback(struct bio *bio);
3732 vn_cache_strategy(struct vnode *vp, struct bio *bio)
3734 struct buf *bp = bio->bio_buf;
3741 * Is this buffer cache buffer suitable for reading from
3744 if (vm_swapcache_read_enable == 0 ||
3745 bp->b_cmd != BUF_CMD_READ ||
3746 ((bp->b_flags & B_CLUSTER) == 0 &&
3747 (bp->b_vp == NULL || (bp->b_flags & B_PAGING))) ||
3748 ((int)bp->b_loffset & PAGE_MASK) != 0 ||
3749 (bp->b_bcount & PAGE_MASK) != 0) {
3754 * Figure out the original VM object (it will match the underlying
3755 * VM pages). Note that swap cached data uses page indices relative
3756 * to that object, not relative to bio->bio_offset.
3758 if (bp->b_flags & B_CLUSTER)
3759 object = vp->v_object;
3761 object = bp->b_vp->v_object;
3764 * In order to be able to use the swap cache all underlying VM
3765 * pages must be marked as such, and we can't have any bogus pages.
3767 for (i = 0; i < bp->b_xio.xio_npages; ++i) {
3768 m = bp->b_xio.xio_pages[i];
3769 if ((m->flags & PG_SWAPPED) == 0)
3771 if (m == bogus_page)
3776 * If we are good then issue the I/O using swap_pager_strategy().
3778 if (i == bp->b_xio.xio_npages) {
3779 m = bp->b_xio.xio_pages[0];
3780 nbio = push_bio(bio);
3781 nbio->bio_done = vn_cache_strategy_callback;
3782 nbio->bio_offset = ptoa(m->pindex);
3783 KKASSERT(m->object == object);
3784 swap_pager_strategy(object, nbio);
3791 * This is a bit of a hack but since the vn_cache_strategy() function can
3792 * override a VFS's strategy function we must make sure that the bio, which
3793 * is probably bio2, doesn't leak an unexpected offset value back to the
3794 * filesystem. The filesystem (e.g. UFS) might otherwise assume that the
3795 * bio went through its own file strategy function and the the bio2 offset
3796 * is a cached disk offset when, in fact, it isn't.
3799 vn_cache_strategy_callback(struct bio *bio)
3801 bio->bio_offset = NOOFFSET;
3802 biodone(pop_bio(bio));
3808 * Finish I/O on a buffer after all BIOs have been processed.
3809 * Called when the bio chain is exhausted or by biowait. If called
3810 * by biowait, elseit is typically 0.
3812 * bpdone is also responsible for setting B_CACHE in a B_VMIO bp.
3813 * In a non-VMIO bp, B_CACHE will be set on the next getblk()
3814 * assuming B_INVAL is clear.
3816 * For the VMIO case, we set B_CACHE if the op was a read and no
3817 * read error occured, or if the op was a write. B_CACHE is never
3818 * set if the buffer is invalid or otherwise uncacheable.
3820 * bpdone does not mess with B_INVAL, allowing the I/O routine or the
3821 * initiator to leave B_INVAL set to brelse the buffer out of existance
3822 * in the biodone routine.
3825 bpdone(struct buf *bp, int elseit)
3829 KASSERT(BUF_REFCNTNB(bp) > 0,
3830 ("biodone: bp %p not busy %d", bp, BUF_REFCNTNB(bp)));
3831 KASSERT(bp->b_cmd != BUF_CMD_DONE,
3832 ("biodone: bp %p already done!", bp));
3835 * No more BIOs are left. All completion functions have been dealt
3836 * with, now we clean up the buffer.
3839 bp->b_cmd = BUF_CMD_DONE;
3842 * Only reads and writes are processed past this point.
3844 if (cmd != BUF_CMD_READ && cmd != BUF_CMD_WRITE) {
3845 if (cmd == BUF_CMD_FREEBLKS)
3846 bp->b_flags |= B_NOCACHE;
3853 * Warning: softupdates may re-dirty the buffer, and HAMMER can do
3854 * a lot worse. XXX - move this above the clearing of b_cmd
3856 if (LIST_FIRST(&bp->b_dep) != NULL)
3857 buf_complete(bp); /* MPSAFE */
3860 * A failed write must re-dirty the buffer unless B_INVAL
3861 * was set. Only applicable to normal buffers (with VPs).
3862 * vinum buffers may not have a vp.
3864 if (cmd == BUF_CMD_WRITE &&
3865 (bp->b_flags & (B_ERROR | B_INVAL)) == B_ERROR) {
3866 bp->b_flags &= ~B_NOCACHE;
3871 if (bp->b_flags & B_VMIO) {
3877 struct vnode *vp = bp->b_vp;
3881 #if defined(VFS_BIO_DEBUG)
3882 if (vp->v_auxrefs == 0)
3883 panic("biodone: zero vnode hold count");
3884 if ((vp->v_flag & VOBJBUF) == 0)
3885 panic("biodone: vnode is not setup for merged cache");
3888 foff = bp->b_loffset;
3889 KASSERT(foff != NOOFFSET, ("biodone: no buffer offset"));
3890 KASSERT(obj != NULL, ("biodone: missing VM object"));
3892 #if defined(VFS_BIO_DEBUG)
3893 if (obj->paging_in_progress < bp->b_xio.xio_npages) {
3894 kprintf("biodone: paging in progress(%d) < bp->b_xio.xio_npages(%d)\n",
3895 obj->paging_in_progress, bp->b_xio.xio_npages);
3900 * Set B_CACHE if the op was a normal read and no error
3901 * occured. B_CACHE is set for writes in the b*write()
3904 iosize = bp->b_bcount - bp->b_resid;
3905 if (cmd == BUF_CMD_READ &&
3906 (bp->b_flags & (B_INVAL|B_NOCACHE|B_ERROR)) == 0) {
3907 bp->b_flags |= B_CACHE;
3910 lwkt_gettoken(&vm_token);
3911 for (i = 0; i < bp->b_xio.xio_npages; i++) {
3915 resid = ((foff + PAGE_SIZE) & ~(off_t)PAGE_MASK) - foff;
3920 * cleanup bogus pages, restoring the originals. Since
3921 * the originals should still be wired, we don't have
3922 * to worry about interrupt/freeing races destroying
3923 * the VM object association.
3925 m = bp->b_xio.xio_pages[i];
3926 if (m == bogus_page) {
3928 m = vm_page_lookup(obj, OFF_TO_IDX(foff));
3930 panic("biodone: page disappeared");
3931 bp->b_xio.xio_pages[i] = m;
3932 pmap_qenter(trunc_page((vm_offset_t)bp->b_data),
3933 bp->b_xio.xio_pages, bp->b_xio.xio_npages);
3935 #if defined(VFS_BIO_DEBUG)
3936 if (OFF_TO_IDX(foff) != m->pindex) {
3937 kprintf("biodone: foff(%lu)/m->pindex(%ld) "
3939 (unsigned long)foff, (long)m->pindex);
3944 * In the write case, the valid and clean bits are
3945 * already changed correctly (see bdwrite()), so we
3946 * only need to do this here in the read case.
3948 if (cmd == BUF_CMD_READ && !bogusflag && resid > 0) {
3949 vfs_clean_one_page(bp, i, m);
3951 vm_page_flag_clear(m, PG_ZERO);
3954 * when debugging new filesystems or buffer I/O
3955 * methods, this is the most common error that pops
3956 * up. if you see this, you have not set the page
3957 * busy flag correctly!!!
3960 kprintf("biodone: page busy < 0, "
3961 "pindex: %d, foff: 0x(%x,%x), "
3962 "resid: %d, index: %d\n",
3963 (int) m->pindex, (int)(foff >> 32),
3964 (int) foff & 0xffffffff, resid, i);
3965 if (!vn_isdisk(vp, NULL))
3966 kprintf(" iosize: %ld, loffset: %lld, "
3967 "flags: 0x%08x, npages: %d\n",
3968 bp->b_vp->v_mount->mnt_stat.f_iosize,
3969 (long long)bp->b_loffset,
3970 bp->b_flags, bp->b_xio.xio_npages);
3972 kprintf(" VDEV, loffset: %lld, flags: 0x%08x, npages: %d\n",
3973 (long long)bp->b_loffset,
3974 bp->b_flags, bp->b_xio.xio_npages);
3975 kprintf(" valid: 0x%x, dirty: 0x%x, wired: %d\n",
3976 m->valid, m->dirty, m->wire_count);
3977 panic("biodone: page busy < 0");
3979 vm_page_io_finish(m);
3980 vm_object_pip_subtract(obj, 1);
3981 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK;
3984 bp->b_flags &= ~B_HASBOGUS;
3986 vm_object_pip_wakeupn(obj, 0);
3987 lwkt_reltoken(&vm_token);
3991 * Finish up by releasing the buffer. There are no more synchronous
3992 * or asynchronous completions, those were handled by bio_done
3996 if (bp->b_flags & (B_NOCACHE|B_INVAL|B_ERROR|B_RELBUF))
4007 biodone(struct bio *bio)
4009 struct buf *bp = bio->bio_buf;
4011 runningbufwakeup(bp);
4014 * Run up the chain of BIO's. Leave b_cmd intact for the duration.
4017 biodone_t *done_func;
4018 struct bio_track *track;
4021 * BIO tracking. Most but not all BIOs are tracked.
4023 if ((track = bio->bio_track) != NULL) {
4024 bio_track_rel(track);
4025 bio->bio_track = NULL;
4029 * A bio_done function terminates the loop. The function
4030 * will be responsible for any further chaining and/or
4031 * buffer management.
4033 * WARNING! The done function can deallocate the buffer!
4035 if ((done_func = bio->bio_done) != NULL) {
4036 bio->bio_done = NULL;
4040 bio = bio->bio_prev;
4044 * If we've run out of bio's do normal [a]synchronous completion.
4050 * Synchronous biodone - this terminates a synchronous BIO.
4052 * bpdone() is called with elseit=FALSE, leaving the buffer completed
4053 * but still locked. The caller must brelse() the buffer after waiting
4057 biodone_sync(struct bio *bio)
4059 struct buf *bp = bio->bio_buf;
4063 KKASSERT(bio == &bp->b_bio1);
4067 flags = bio->bio_flags;
4068 nflags = (flags | BIO_DONE) & ~BIO_WANT;
4070 if (atomic_cmpset_int(&bio->bio_flags, flags, nflags)) {
4071 if (flags & BIO_WANT)
4081 * This routine is called in lieu of iodone in the case of
4082 * incomplete I/O. This keeps the busy status for pages
4086 vfs_unbusy_pages(struct buf *bp)
4090 runningbufwakeup(bp);
4092 lwkt_gettoken(&vm_token);
4093 if (bp->b_flags & B_VMIO) {
4094 struct vnode *vp = bp->b_vp;
4099 for (i = 0; i < bp->b_xio.xio_npages; i++) {
4100 vm_page_t m = bp->b_xio.xio_pages[i];
4103 * When restoring bogus changes the original pages
4104 * should still be wired, so we are in no danger of
4105 * losing the object association and do not need
4106 * critical section protection particularly.
4108 if (m == bogus_page) {
4109 m = vm_page_lookup(obj, OFF_TO_IDX(bp->b_loffset) + i);
4111 panic("vfs_unbusy_pages: page missing");
4113 bp->b_xio.xio_pages[i] = m;
4114 pmap_qenter(trunc_page((vm_offset_t)bp->b_data),
4115 bp->b_xio.xio_pages, bp->b_xio.xio_npages);
4117 vm_object_pip_subtract(obj, 1);
4118 vm_page_flag_clear(m, PG_ZERO);
4119 vm_page_io_finish(m);
4121 bp->b_flags &= ~B_HASBOGUS;
4122 vm_object_pip_wakeupn(obj, 0);
4124 lwkt_reltoken(&vm_token);
4130 * This routine is called before a device strategy routine.
4131 * It is used to tell the VM system that paging I/O is in
4132 * progress, and treat the pages associated with the buffer
4133 * almost as being PG_BUSY. Also the object 'paging_in_progress'
4134 * flag is handled to make sure that the object doesn't become
4137 * Since I/O has not been initiated yet, certain buffer flags
4138 * such as B_ERROR or B_INVAL may be in an inconsistant state
4139 * and should be ignored.
4144 vfs_busy_pages(struct vnode *vp, struct buf *bp)
4147 struct lwp *lp = curthread->td_lwp;
4150 * The buffer's I/O command must already be set. If reading,
4151 * B_CACHE must be 0 (double check against callers only doing
4152 * I/O when B_CACHE is 0).
4154 KKASSERT(bp->b_cmd != BUF_CMD_DONE);
4155 KKASSERT(bp->b_cmd == BUF_CMD_WRITE || (bp->b_flags & B_CACHE) == 0);
4157 if (bp->b_flags & B_VMIO) {
4160 lwkt_gettoken(&vm_token);
4163 KASSERT(bp->b_loffset != NOOFFSET,
4164 ("vfs_busy_pages: no buffer offset"));
4167 * Loop until none of the pages are busy.
4170 for (i = 0; i < bp->b_xio.xio_npages; i++) {
4171 vm_page_t m = bp->b_xio.xio_pages[i];
4173 if (vm_page_sleep_busy(m, FALSE, "vbpage"))
4178 * Setup for I/O, soft-busy the page right now because
4179 * the next loop may block.
4181 for (i = 0; i < bp->b_xio.xio_npages; i++) {
4182 vm_page_t m = bp->b_xio.xio_pages[i];
4184 vm_page_flag_clear(m, PG_ZERO);
4185 if ((bp->b_flags & B_CLUSTER) == 0) {
4186 vm_object_pip_add(obj, 1);
4187 vm_page_io_start(m);
4192 * Adjust protections for I/O and do bogus-page mapping.
4193 * Assume that vm_page_protect() can block (it can block
4194 * if VM_PROT_NONE, don't take any chances regardless).
4196 * In particular note that for writes we must incorporate
4197 * page dirtyness from the VM system into the buffer's
4200 * For reads we theoretically must incorporate page dirtyness
4201 * from the VM system to determine if the page needs bogus
4202 * replacement, but we shortcut the test by simply checking
4203 * that all m->valid bits are set, indicating that the page
4204 * is fully valid and does not need to be re-read. For any
4205 * VM system dirtyness the page will also be fully valid
4206 * since it was mapped at one point.
4209 for (i = 0; i < bp->b_xio.xio_npages; i++) {
4210 vm_page_t m = bp->b_xio.xio_pages[i];
4212 vm_page_flag_clear(m, PG_ZERO); /* XXX */
4213 if (bp->b_cmd == BUF_CMD_WRITE) {
4215 * When readying a vnode-backed buffer for
4216 * a write we must zero-fill any invalid
4217 * portions of the backing VM pages, mark
4218 * it valid and clear related dirty bits.
4220 * vfs_clean_one_page() incorporates any
4221 * VM dirtyness and updates the b_dirtyoff
4222 * range (after we've made the page RO).
4224 * It is also expected that the pmap modified
4225 * bit has already been cleared by the
4226 * vm_page_protect(). We may not be able
4227 * to clear all dirty bits for a page if it
4228 * was also memory mapped (NFS).
4230 * Finally be sure to unassign any swap-cache
4231 * backing store as it is now stale.
4233 vm_page_protect(m, VM_PROT_READ);
4234 vfs_clean_one_page(bp, i, m);
4235 swap_pager_unswapped(m);
4236 } else if (m->valid == VM_PAGE_BITS_ALL) {
4238 * When readying a vnode-backed buffer for
4239 * read we must replace any dirty pages with
4240 * a bogus page so dirty data is not destroyed
4241 * when filling gaps.
4243 * To avoid testing whether the page is
4244 * dirty we instead test that the page was
4245 * at some point mapped (m->valid fully
4246 * valid) with the understanding that
4247 * this also covers the dirty case.
4249 bp->b_xio.xio_pages[i] = bogus_page;
4250 bp->b_flags |= B_HASBOGUS;
4252 } else if (m->valid & m->dirty) {
4254 * This case should not occur as partial
4255 * dirtyment can only happen if the buffer
4256 * is B_CACHE, and this code is not entered
4257 * if the buffer is B_CACHE.
4259 kprintf("Warning: vfs_busy_pages - page not "
4260 "fully valid! loff=%jx bpf=%08x "
4261 "idx=%d val=%02x dir=%02x\n",
4262 (intmax_t)bp->b_loffset, bp->b_flags,
4263 i, m->valid, m->dirty);
4264 vm_page_protect(m, VM_PROT_NONE);
4267 * The page is not valid and can be made
4270 vm_page_protect(m, VM_PROT_NONE);
4274 pmap_qenter(trunc_page((vm_offset_t)bp->b_data),
4275 bp->b_xio.xio_pages, bp->b_xio.xio_npages);
4277 lwkt_reltoken(&vm_token);
4281 * This is the easiest place to put the process accounting for the I/O
4285 if (bp->b_cmd == BUF_CMD_READ)
4286 lp->lwp_ru.ru_inblock++;
4288 lp->lwp_ru.ru_oublock++;
4293 * Tell the VM system that the pages associated with this buffer
4294 * are clean. This is used for delayed writes where the data is
4295 * going to go to disk eventually without additional VM intevention.
4297 * NOTE: While we only really need to clean through to b_bcount, we
4298 * just go ahead and clean through to b_bufsize.
4301 vfs_clean_pages(struct buf *bp)
4306 if ((bp->b_flags & B_VMIO) == 0)
4309 KASSERT(bp->b_loffset != NOOFFSET,
4310 ("vfs_clean_pages: no buffer offset"));
4313 * vm_token must be held for vfs_clean_one_page() calls.
4315 lwkt_gettoken(&vm_token);
4316 for (i = 0; i < bp->b_xio.xio_npages; i++) {
4317 m = bp->b_xio.xio_pages[i];
4318 vfs_clean_one_page(bp, i, m);
4320 lwkt_reltoken(&vm_token);
4324 * vfs_clean_one_page:
4326 * Set the valid bits and clear the dirty bits in a page within a
4327 * buffer. The range is restricted to the buffer's size and the
4328 * buffer's logical offset might index into the first page.
4330 * The caller has busied or soft-busied the page and it is not mapped,
4331 * test and incorporate the dirty bits into b_dirtyoff/end before
4332 * clearing them. Note that we need to clear the pmap modified bits
4333 * after determining the the page was dirty, vm_page_set_validclean()
4334 * does not do it for us.
4336 * This routine is typically called after a read completes (dirty should
4337 * be zero in that case as we are not called on bogus-replace pages),
4338 * or before a write is initiated.
4340 * NOTE: vm_token must be held by the caller, and vm_page_set_validclean()
4341 * currently assumes the vm_token is held.
4344 vfs_clean_one_page(struct buf *bp, int pageno, vm_page_t m)
4352 * Calculate offset range within the page but relative to buffer's
4353 * loffset. loffset might be offset into the first page.
4355 xoff = (int)bp->b_loffset & PAGE_MASK; /* loffset offset into pg 0 */
4356 bcount = bp->b_bcount + xoff; /* offset adjusted */
4362 soff = (pageno << PAGE_SHIFT);
4363 eoff = soff + PAGE_SIZE;
4371 * Test dirty bits and adjust b_dirtyoff/end.
4373 * If dirty pages are incorporated into the bp any prior
4374 * B_NEEDCOMMIT state (NFS) must be cleared because the
4375 * caller has not taken into account the new dirty data.
4377 * If the page was memory mapped the dirty bits might go beyond the
4378 * end of the buffer, but we can't really make the assumption that
4379 * a file EOF straddles the buffer (even though this is the case for
4380 * NFS if B_NEEDCOMMIT is also set). So for the purposes of clearing
4381 * B_NEEDCOMMIT we only test the dirty bits covered by the buffer.
4382 * This also saves some console spam.
4384 * When clearing B_NEEDCOMMIT we must also clear B_CLUSTEROK,
4385 * NFS can handle huge commits but not huge writes.
4387 vm_page_test_dirty(m);
4389 if ((bp->b_flags & B_NEEDCOMMIT) &&
4390 (m->dirty & vm_page_bits(soff & PAGE_MASK, eoff - soff))) {
4392 kprintf("Warning: vfs_clean_one_page: bp %p "
4393 "loff=%jx,%d flgs=%08x clr B_NEEDCOMMIT"
4394 " cmd %d vd %02x/%02x x/s/e %d %d %d "
4396 bp, (intmax_t)bp->b_loffset, bp->b_bcount,
4397 bp->b_flags, bp->b_cmd,
4398 m->valid, m->dirty, xoff, soff, eoff,
4399 bp->b_dirtyoff, bp->b_dirtyend);
4400 bp->b_flags &= ~(B_NEEDCOMMIT | B_CLUSTEROK);
4402 print_backtrace(-1);
4405 * Only clear the pmap modified bits if ALL the dirty bits
4406 * are set, otherwise the system might mis-clear portions
4409 if (m->dirty == VM_PAGE_BITS_ALL &&
4410 (bp->b_flags & B_NEEDCOMMIT) == 0) {
4411 pmap_clear_modify(m);
4413 if (bp->b_dirtyoff > soff - xoff)
4414 bp->b_dirtyoff = soff - xoff;
4415 if (bp->b_dirtyend < eoff - xoff)
4416 bp->b_dirtyend = eoff - xoff;
4420 * Set related valid bits, clear related dirty bits.
4421 * Does not mess with the pmap modified bit.
4423 * WARNING! We cannot just clear all of m->dirty here as the
4424 * buffer cache buffers may use a DEV_BSIZE'd aligned
4425 * block size, or have an odd size (e.g. NFS at file EOF).
4426 * The putpages code can clear m->dirty to 0.
4428 * If a VOP_WRITE generates a buffer cache buffer which
4429 * covers the same space as mapped writable pages the
4430 * buffer flush might not be able to clear all the dirty
4431 * bits and still require a putpages from the VM system
4434 * WARNING! vm_page_set_validclean() currently assumes vm_token
4435 * is held. The page might not be busied (bdwrite() case).
4437 vm_page_set_validclean(m, soff & PAGE_MASK, eoff - soff);
4441 * Similar to vfs_clean_one_page() but sets the bits to valid and dirty.
4442 * The page data is assumed to be valid (there is no zeroing here).
4445 vfs_dirty_one_page(struct buf *bp, int pageno, vm_page_t m)
4453 * Calculate offset range within the page but relative to buffer's
4454 * loffset. loffset might be offset into the first page.
4456 xoff = (int)bp->b_loffset & PAGE_MASK; /* loffset offset into pg 0 */
4457 bcount = bp->b_bcount + xoff; /* offset adjusted */
4463 soff = (pageno << PAGE_SHIFT);
4464 eoff = soff + PAGE_SIZE;
4470 vm_page_set_validdirty(m, soff & PAGE_MASK, eoff - soff);
4476 * Clear a buffer. This routine essentially fakes an I/O, so we need
4477 * to clear B_ERROR and B_INVAL.
4479 * Note that while we only theoretically need to clear through b_bcount,
4480 * we go ahead and clear through b_bufsize.
4484 vfs_bio_clrbuf(struct buf *bp)
4488 if ((bp->b_flags & (B_VMIO | B_MALLOC)) == B_VMIO) {
4489 bp->b_flags &= ~(B_INVAL | B_EINTR | B_ERROR);
4490 if ((bp->b_xio.xio_npages == 1) && (bp->b_bufsize < PAGE_SIZE) &&
4491 (bp->b_loffset & PAGE_MASK) == 0) {
4492 mask = (1 << (bp->b_bufsize / DEV_BSIZE)) - 1;
4493 if ((bp->b_xio.xio_pages[0]->valid & mask) == mask) {
4497 if (((bp->b_xio.xio_pages[0]->flags & PG_ZERO) == 0) &&
4498 ((bp->b_xio.xio_pages[0]->valid & mask) == 0)) {
4499 bzero(bp->b_data, bp->b_bufsize);
4500 bp->b_xio.xio_pages[0]->valid |= mask;
4506 for(i=0;i<bp->b_xio.xio_npages;i++,sa=ea) {
4507 int j = ((vm_offset_t)sa & PAGE_MASK) / DEV_BSIZE;
4508 ea = (caddr_t)trunc_page((vm_offset_t)sa + PAGE_SIZE);
4509 ea = (caddr_t)(vm_offset_t)ulmin(
4510 (u_long)(vm_offset_t)ea,
4511 (u_long)(vm_offset_t)bp->b_data + bp->b_bufsize);
4512 mask = ((1 << ((ea - sa) / DEV_BSIZE)) - 1) << j;
4513 if ((bp->b_xio.xio_pages[i]->valid & mask) == mask)
4515 if ((bp->b_xio.xio_pages[i]->valid & mask) == 0) {
4516 if ((bp->b_xio.xio_pages[i]->flags & PG_ZERO) == 0) {
4520 for (; sa < ea; sa += DEV_BSIZE, j++) {
4521 if (((bp->b_xio.xio_pages[i]->flags & PG_ZERO) == 0) &&
4522 (bp->b_xio.xio_pages[i]->valid & (1<<j)) == 0)
4523 bzero(sa, DEV_BSIZE);
4526 bp->b_xio.xio_pages[i]->valid |= mask;
4527 vm_page_flag_clear(bp->b_xio.xio_pages[i], PG_ZERO);
4536 * vm_hold_load_pages:
4538 * Load pages into the buffer's address space. The pages are
4539 * allocated from the kernel object in order to reduce interference
4540 * with the any VM paging I/O activity. The range of loaded
4541 * pages will be wired.
4543 * If a page cannot be allocated, the 'pagedaemon' is woken up to
4544 * retrieve the full range (to - from) of pages.
4549 vm_hold_load_pages(struct buf *bp, vm_offset_t from, vm_offset_t to)
4555 to = round_page(to);
4556 from = round_page(from);
4557 index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT;
4562 * Note: must allocate system pages since blocking here
4563 * could intefere with paging I/O, no matter which
4566 p = bio_page_alloc(&kernel_object, pg >> PAGE_SHIFT,
4567 (vm_pindex_t)((to - pg) >> PAGE_SHIFT));
4570 p->valid = VM_PAGE_BITS_ALL;
4571 vm_page_flag_clear(p, PG_ZERO);
4572 pmap_kenter(pg, VM_PAGE_TO_PHYS(p));
4573 bp->b_xio.xio_pages[index] = p;
4580 bp->b_xio.xio_npages = index;
4584 * Allocate pages for a buffer cache buffer.
4586 * Under extremely severe memory conditions even allocating out of the
4587 * system reserve can fail. If this occurs we must allocate out of the
4588 * interrupt reserve to avoid a deadlock with the pageout daemon.
4590 * The pageout daemon can run (putpages -> VOP_WRITE -> getblk -> allocbuf).
4591 * If the buffer cache's vm_page_alloc() fails a vm_wait() can deadlock
4592 * against the pageout daemon if pages are not freed from other sources.
4598 bio_page_alloc(vm_object_t obj, vm_pindex_t pg, int deficit)
4603 * Try a normal allocation, allow use of system reserve.
4605 lwkt_gettoken(&vm_token);
4606 p = vm_page_alloc(obj, pg, VM_ALLOC_NORMAL | VM_ALLOC_SYSTEM);
4608 lwkt_reltoken(&vm_token);
4613 * The normal allocation failed and we clearly have a page
4614 * deficit. Try to reclaim some clean VM pages directly
4615 * from the buffer cache.
4617 vm_pageout_deficit += deficit;
4621 * We may have blocked, the caller will know what to do if the
4624 if (vm_page_lookup(obj, pg)) {
4625 lwkt_reltoken(&vm_token);
4630 * Allocate and allow use of the interrupt reserve.
4632 * If after all that we still can't allocate a VM page we are
4633 * in real trouble, but we slog on anyway hoping that the system
4636 p = vm_page_alloc(obj, pg, VM_ALLOC_NORMAL | VM_ALLOC_SYSTEM |
4637 VM_ALLOC_INTERRUPT);
4639 if (vm_page_count_severe()) {
4641 vm_wait(hz / 20 + 1);
4644 kprintf("bio_page_alloc: Memory exhausted during bufcache "
4645 "page allocation\n");
4649 lwkt_reltoken(&vm_token);
4654 * vm_hold_free_pages:
4656 * Return pages associated with the buffer back to the VM system.
4658 * The range of pages underlying the buffer's address space will
4659 * be unmapped and un-wired.
4664 vm_hold_free_pages(struct buf *bp, vm_offset_t from, vm_offset_t to)
4668 int index, newnpages;
4670 from = round_page(from);
4671 to = round_page(to);
4672 index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT;
4675 lwkt_gettoken(&vm_token);
4676 for (pg = from; pg < to; pg += PAGE_SIZE, index++) {
4677 p = bp->b_xio.xio_pages[index];
4678 if (p && (index < bp->b_xio.xio_npages)) {
4680 kprintf("vm_hold_free_pages: doffset: %lld, "
4682 (long long)bp->b_bio2.bio_offset,
4683 (long long)bp->b_loffset);
4685 bp->b_xio.xio_pages[index] = NULL;
4688 vm_page_unwire(p, 0);
4692 bp->b_xio.xio_npages = newnpages;
4693 lwkt_reltoken(&vm_token);
4699 * Map a user buffer into KVM via a pbuf. On return the buffer's
4700 * b_data, b_bufsize, and b_bcount will be set, and its XIO page array
4704 vmapbuf(struct buf *bp, caddr_t udata, int bytes)
4715 * bp had better have a command and it better be a pbuf.
4717 KKASSERT(bp->b_cmd != BUF_CMD_DONE);
4718 KKASSERT(bp->b_flags & B_PAGING);
4719 KKASSERT(bp->b_kvabase);
4725 * Map the user data into KVM. Mappings have to be page-aligned.
4727 addr = (caddr_t)trunc_page((vm_offset_t)udata);
4730 vmprot = VM_PROT_READ;
4731 if (bp->b_cmd == BUF_CMD_READ)
4732 vmprot |= VM_PROT_WRITE;
4734 while (addr < udata + bytes) {
4736 * Do the vm_fault if needed; do the copy-on-write thing
4737 * when reading stuff off device into memory.
4739 * vm_fault_page*() returns a held VM page.
4741 va = (addr >= udata) ? (vm_offset_t)addr : (vm_offset_t)udata;
4742 va = trunc_page(va);
4744 m = vm_fault_page_quick(va, vmprot, &error);
4746 for (i = 0; i < pidx; ++i) {
4747 vm_page_unhold(bp->b_xio.xio_pages[i]);
4748 bp->b_xio.xio_pages[i] = NULL;
4752 bp->b_xio.xio_pages[pidx] = m;
4758 * Map the page array and set the buffer fields to point to
4759 * the mapped data buffer.
4761 if (pidx > btoc(MAXPHYS))
4762 panic("vmapbuf: mapped more than MAXPHYS");
4763 pmap_qenter((vm_offset_t)bp->b_kvabase, bp->b_xio.xio_pages, pidx);
4765 bp->b_xio.xio_npages = pidx;
4766 bp->b_data = bp->b_kvabase + ((int)(intptr_t)udata & PAGE_MASK);
4767 bp->b_bcount = bytes;
4768 bp->b_bufsize = bytes;
4775 * Free the io map PTEs associated with this IO operation.
4776 * We also invalidate the TLB entries and restore the original b_addr.
4779 vunmapbuf(struct buf *bp)
4784 KKASSERT(bp->b_flags & B_PAGING);
4786 npages = bp->b_xio.xio_npages;
4787 pmap_qremove(trunc_page((vm_offset_t)bp->b_data), npages);
4788 for (pidx = 0; pidx < npages; ++pidx) {
4789 vm_page_unhold(bp->b_xio.xio_pages[pidx]);
4790 bp->b_xio.xio_pages[pidx] = NULL;
4792 bp->b_xio.xio_npages = 0;
4793 bp->b_data = bp->b_kvabase;
4797 * Scan all buffers in the system and issue the callback.
4800 scan_all_buffers(int (*callback)(struct buf *, void *), void *info)
4806 for (n = 0; n < nbuf; ++n) {
4807 if ((error = callback(&buf[n], info)) < 0) {
4817 * nestiobuf_iodone: biodone callback for nested buffers and propagate
4818 * completion to the master buffer.
4821 nestiobuf_iodone(struct bio *bio)
4824 struct buf *mbp, *bp;
4825 struct devstat *stats;
4830 mbio = bio->bio_caller_info1.ptr;
4831 stats = bio->bio_caller_info2.ptr;
4832 mbp = mbio->bio_buf;
4834 KKASSERT(bp->b_bcount <= bp->b_bufsize);
4835 KKASSERT(mbp != bp);
4837 error = bp->b_error;
4838 if (bp->b_error == 0 &&
4839 (bp->b_bcount < bp->b_bufsize || bp->b_resid > 0)) {
4841 * Not all got transfered, raise an error. We have no way to
4842 * propagate these conditions to mbp.
4847 donebytes = bp->b_bufsize;
4851 nestiobuf_done(mbio, donebytes, error, stats);
4855 nestiobuf_done(struct bio *mbio, int donebytes, int error, struct devstat *stats)
4859 mbp = mbio->bio_buf;
4861 KKASSERT((int)(intptr_t)mbio->bio_driver_info > 0);
4864 * If an error occured, propagate it to the master buffer.
4866 * Several biodone()s may wind up running concurrently so
4867 * use an atomic op to adjust b_flags.
4870 mbp->b_error = error;
4871 atomic_set_int(&mbp->b_flags, B_ERROR);
4875 * Decrement the operations in progress counter and terminate the
4876 * I/O if this was the last bit.
4878 if (atomic_fetchadd_int((int *)&mbio->bio_driver_info, -1) == 1) {
4881 devstat_end_transaction_buf(stats, mbp);
4887 * Initialize a nestiobuf for use. Set an initial count of 1 to prevent
4888 * the mbio from being biodone()'d while we are still adding sub-bios to
4892 nestiobuf_init(struct bio *bio)
4894 bio->bio_driver_info = (void *)1;
4898 * The BIOs added to the nestedio have already been started, remove the
4899 * count that placeheld our mbio and biodone() it if the count would
4903 nestiobuf_start(struct bio *mbio)
4905 struct buf *mbp = mbio->bio_buf;
4908 * Decrement the operations in progress counter and terminate the
4909 * I/O if this was the last bit.
4911 if (atomic_fetchadd_int((int *)&mbio->bio_driver_info, -1) == 1) {
4912 if (mbp->b_flags & B_ERROR)
4913 mbp->b_resid = mbp->b_bcount;
4921 * Set an intermediate error prior to calling nestiobuf_start()
4924 nestiobuf_error(struct bio *mbio, int error)
4926 struct buf *mbp = mbio->bio_buf;
4929 mbp->b_error = error;
4930 atomic_set_int(&mbp->b_flags, B_ERROR);
4935 * nestiobuf_add: setup a "nested" buffer.
4937 * => 'mbp' is a "master" buffer which is being divided into sub pieces.
4938 * => 'bp' should be a buffer allocated by getiobuf.
4939 * => 'offset' is a byte offset in the master buffer.
4940 * => 'size' is a size in bytes of this nested buffer.
4943 nestiobuf_add(struct bio *mbio, struct buf *bp, int offset, size_t size, struct devstat *stats)
4945 struct buf *mbp = mbio->bio_buf;
4946 struct vnode *vp = mbp->b_vp;
4948 KKASSERT(mbp->b_bcount >= offset + size);
4950 atomic_add_int((int *)&mbio->bio_driver_info, 1);
4952 /* kernel needs to own the lock for it to be released in biodone */
4955 bp->b_cmd = mbp->b_cmd;
4956 bp->b_bio1.bio_done = nestiobuf_iodone;
4957 bp->b_data = (char *)mbp->b_data + offset;
4958 bp->b_resid = bp->b_bcount = size;
4959 bp->b_bufsize = bp->b_bcount;
4961 bp->b_bio1.bio_track = NULL;
4962 bp->b_bio1.bio_caller_info1.ptr = mbio;
4963 bp->b_bio1.bio_caller_info2.ptr = stats;
4967 * print out statistics from the current status of the buffer pool
4968 * this can be toggeled by the system control option debug.syncprt
4977 int counts[(MAXBSIZE / PAGE_SIZE) + 1];
4978 static char *bname[3] = { "LOCKED", "LRU", "AGE" };
4980 for (dp = bufqueues, i = 0; dp < &bufqueues[3]; dp++, i++) {
4982 for (j = 0; j <= MAXBSIZE/PAGE_SIZE; j++)
4985 spin_lock(&bufqspin);
4986 TAILQ_FOREACH(bp, dp, b_freelist) {
4987 counts[bp->b_bufsize/PAGE_SIZE]++;
4990 spin_unlock(&bufqspin);
4992 kprintf("%s: total-%d", bname[i], count);
4993 for (j = 0; j <= MAXBSIZE/PAGE_SIZE; j++)
4995 kprintf(", %d-%d", j * PAGE_SIZE, counts[j]);
5003 DB_SHOW_COMMAND(buffer, db_show_buffer)
5006 struct buf *bp = (struct buf *)addr;
5009 db_printf("usage: show buffer <addr>\n");
5013 db_printf("b_flags = 0x%b\n", (u_int)bp->b_flags, PRINT_BUF_FLAGS);
5014 db_printf("b_cmd = %d\n", bp->b_cmd);
5015 db_printf("b_error = %d, b_bufsize = %d, b_bcount = %d, "
5016 "b_resid = %d\n, b_data = %p, "
5017 "bio_offset(disk) = %lld, bio_offset(phys) = %lld\n",
5018 bp->b_error, bp->b_bufsize, bp->b_bcount, bp->b_resid,
5020 (long long)bp->b_bio2.bio_offset,
5021 (long long)(bp->b_bio2.bio_next ?
5022 bp->b_bio2.bio_next->bio_offset : (off_t)-1));
5023 if (bp->b_xio.xio_npages) {
5025 db_printf("b_xio.xio_npages = %d, pages(OBJ, IDX, PA): ",
5026 bp->b_xio.xio_npages);
5027 for (i = 0; i < bp->b_xio.xio_npages; i++) {
5029 m = bp->b_xio.xio_pages[i];
5030 db_printf("(%p, 0x%lx, 0x%lx)", (void *)m->object,
5031 (u_long)m->pindex, (u_long)VM_PAGE_TO_PHYS(m));
5032 if ((i + 1) < bp->b_xio.xio_npages)