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"));
908 * Operates like bread, but also starts asynchronous I/O on
909 * read-ahead blocks. We must clear B_ERROR and B_INVAL prior
910 * to initiating I/O . If B_CACHE is set, the buffer is valid
911 * and we do not have to do anything.
916 breadn(struct vnode *vp, off_t loffset, int size, off_t *raoffset,
917 int *rabsize, int cnt, struct buf **bpp)
919 struct buf *bp, *rabp;
921 int rv = 0, readwait = 0;
923 *bpp = bp = getblk(vp, loffset, size, 0, 0);
925 /* if not found in cache, do some I/O */
926 if ((bp->b_flags & B_CACHE) == 0) {
927 bp->b_flags &= ~(B_ERROR | B_EINTR | B_INVAL);
928 bp->b_cmd = BUF_CMD_READ;
929 bp->b_bio1.bio_done = biodone_sync;
930 bp->b_bio1.bio_flags |= BIO_SYNC;
931 vfs_busy_pages(vp, bp);
932 vn_strategy(vp, &bp->b_bio1);
936 for (i = 0; i < cnt; i++, raoffset++, rabsize++) {
937 if (inmem(vp, *raoffset))
939 rabp = getblk(vp, *raoffset, *rabsize, 0, 0);
941 if ((rabp->b_flags & B_CACHE) == 0) {
942 rabp->b_flags &= ~(B_ERROR | B_EINTR | B_INVAL);
943 rabp->b_cmd = BUF_CMD_READ;
944 vfs_busy_pages(vp, rabp);
946 vn_strategy(vp, &rabp->b_bio1);
952 rv = biowait(&bp->b_bio1, "biord");
959 * Synchronous write, waits for completion.
961 * Write, release buffer on completion. (Done by iodone
962 * if async). Do not bother writing anything if the buffer
965 * Note that we set B_CACHE here, indicating that buffer is
966 * fully valid and thus cacheable. This is true even of NFS
967 * now so we set it generally. This could be set either here
968 * or in biodone() since the I/O is synchronous. We put it
972 bwrite(struct buf *bp)
976 if (bp->b_flags & B_INVAL) {
980 if (BUF_REFCNTNB(bp) == 0)
981 panic("bwrite: buffer is not busy???");
983 /* Mark the buffer clean */
986 bp->b_flags &= ~(B_ERROR | B_EINTR);
987 bp->b_flags |= B_CACHE;
988 bp->b_cmd = BUF_CMD_WRITE;
989 bp->b_bio1.bio_done = biodone_sync;
990 bp->b_bio1.bio_flags |= BIO_SYNC;
991 vfs_busy_pages(bp->b_vp, bp);
994 * Normal bwrites pipeline writes. NOTE: b_bufsize is only
995 * valid for vnode-backed buffers.
997 bsetrunningbufspace(bp, bp->b_bufsize);
998 vn_strategy(bp->b_vp, &bp->b_bio1);
999 error = biowait(&bp->b_bio1, "biows");
1008 * Asynchronous write. Start output on a buffer, but do not wait for
1009 * it to complete. The buffer is released when the output completes.
1011 * bwrite() ( or the VOP routine anyway ) is responsible for handling
1012 * B_INVAL buffers. Not us.
1015 bawrite(struct buf *bp)
1017 if (bp->b_flags & B_INVAL) {
1021 if (BUF_REFCNTNB(bp) == 0)
1022 panic("bwrite: buffer is not busy???");
1024 /* Mark the buffer clean */
1027 bp->b_flags &= ~(B_ERROR | B_EINTR);
1028 bp->b_flags |= B_CACHE;
1029 bp->b_cmd = BUF_CMD_WRITE;
1030 KKASSERT(bp->b_bio1.bio_done == NULL);
1031 vfs_busy_pages(bp->b_vp, bp);
1034 * Normal bwrites pipeline writes. NOTE: b_bufsize is only
1035 * valid for vnode-backed buffers.
1037 bsetrunningbufspace(bp, bp->b_bufsize);
1039 vn_strategy(bp->b_vp, &bp->b_bio1);
1045 * Ordered write. Start output on a buffer, and flag it so that the
1046 * device will write it in the order it was queued. The buffer is
1047 * released when the output completes. bwrite() ( or the VOP routine
1048 * anyway ) is responsible for handling B_INVAL buffers.
1051 bowrite(struct buf *bp)
1053 bp->b_flags |= B_ORDERED;
1061 * Delayed write. (Buffer is marked dirty). Do not bother writing
1062 * anything if the buffer is marked invalid.
1064 * Note that since the buffer must be completely valid, we can safely
1065 * set B_CACHE. In fact, we have to set B_CACHE here rather then in
1066 * biodone() in order to prevent getblk from writing the buffer
1067 * out synchronously.
1070 bdwrite(struct buf *bp)
1072 if (BUF_REFCNTNB(bp) == 0)
1073 panic("bdwrite: buffer is not busy");
1075 if (bp->b_flags & B_INVAL) {
1081 if (dsched_is_clear_buf_priv(bp))
1085 * Set B_CACHE, indicating that the buffer is fully valid. This is
1086 * true even of NFS now.
1088 bp->b_flags |= B_CACHE;
1091 * This bmap keeps the system from needing to do the bmap later,
1092 * perhaps when the system is attempting to do a sync. Since it
1093 * is likely that the indirect block -- or whatever other datastructure
1094 * that the filesystem needs is still in memory now, it is a good
1095 * thing to do this. Note also, that if the pageout daemon is
1096 * requesting a sync -- there might not be enough memory to do
1097 * the bmap then... So, this is important to do.
1099 if (bp->b_bio2.bio_offset == NOOFFSET) {
1100 VOP_BMAP(bp->b_vp, bp->b_loffset, &bp->b_bio2.bio_offset,
1101 NULL, NULL, BUF_CMD_WRITE);
1105 * Because the underlying pages may still be mapped and
1106 * writable trying to set the dirty buffer (b_dirtyoff/end)
1107 * range here will be inaccurate.
1109 * However, we must still clean the pages to satisfy the
1110 * vnode_pager and pageout daemon, so theythink the pages
1111 * have been "cleaned". What has really occured is that
1112 * they've been earmarked for later writing by the buffer
1115 * So we get the b_dirtyoff/end update but will not actually
1116 * depend on it (NFS that is) until the pages are busied for
1119 vfs_clean_pages(bp);
1123 * note: we cannot initiate I/O from a bdwrite even if we wanted to,
1124 * due to the softdep code.
1129 * Fake write - return pages to VM system as dirty, leave the buffer clean.
1130 * This is used by tmpfs.
1132 * It is important for any VFS using this routine to NOT use it for
1133 * IO_SYNC or IO_ASYNC operations which occur when the system really
1134 * wants to flush VM pages to backing store.
1137 buwrite(struct buf *bp)
1143 * Only works for VMIO buffers. If the buffer is already
1144 * marked for delayed-write we can't avoid the bdwrite().
1146 if ((bp->b_flags & B_VMIO) == 0 || (bp->b_flags & B_DELWRI)) {
1152 * Set valid & dirty.
1154 * WARNING! vfs_dirty_one_page() assumes vm_token is held for now.
1156 lwkt_gettoken(&vm_token);
1157 for (i = 0; i < bp->b_xio.xio_npages; i++) {
1158 m = bp->b_xio.xio_pages[i];
1159 vfs_dirty_one_page(bp, i, m);
1161 lwkt_reltoken(&vm_token);
1168 * Turn buffer into delayed write request by marking it B_DELWRI.
1169 * B_RELBUF and B_NOCACHE must be cleared.
1171 * We reassign the buffer to itself to properly update it in the
1172 * dirty/clean lists.
1174 * Must be called from a critical section.
1175 * The buffer must be on BQUEUE_NONE.
1178 bdirty(struct buf *bp)
1180 KASSERT(bp->b_qindex == BQUEUE_NONE, ("bdirty: buffer %p still on queue %d", bp, bp->b_qindex));
1181 if (bp->b_flags & B_NOCACHE) {
1182 kprintf("bdirty: clearing B_NOCACHE on buf %p\n", bp);
1183 bp->b_flags &= ~B_NOCACHE;
1185 if (bp->b_flags & B_INVAL) {
1186 kprintf("bdirty: warning, dirtying invalid buffer %p\n", bp);
1188 bp->b_flags &= ~B_RELBUF;
1190 if ((bp->b_flags & B_DELWRI) == 0) {
1191 lwkt_gettoken(&bp->b_vp->v_token);
1192 bp->b_flags |= B_DELWRI;
1194 lwkt_reltoken(&bp->b_vp->v_token);
1196 spin_lock(&bufcspin);
1198 dirtybufspace += bp->b_bufsize;
1199 if (bp->b_flags & B_HEAVY) {
1201 dirtybufspacehw += bp->b_bufsize;
1203 spin_unlock(&bufcspin);
1210 * Set B_HEAVY, indicating that this is a heavy-weight buffer that
1211 * needs to be flushed with a different buf_daemon thread to avoid
1212 * deadlocks. B_HEAVY also imposes restrictions in getnewbuf().
1215 bheavy(struct buf *bp)
1217 if ((bp->b_flags & B_HEAVY) == 0) {
1218 bp->b_flags |= B_HEAVY;
1219 if (bp->b_flags & B_DELWRI) {
1220 spin_lock(&bufcspin);
1222 dirtybufspacehw += bp->b_bufsize;
1223 spin_unlock(&bufcspin);
1231 * Clear B_DELWRI for buffer.
1233 * Must be called from a critical section.
1235 * The buffer is typically on BQUEUE_NONE but there is one case in
1236 * brelse() that calls this function after placing the buffer on
1237 * a different queue.
1242 bundirty(struct buf *bp)
1244 if (bp->b_flags & B_DELWRI) {
1245 lwkt_gettoken(&bp->b_vp->v_token);
1246 bp->b_flags &= ~B_DELWRI;
1248 lwkt_reltoken(&bp->b_vp->v_token);
1250 spin_lock(&bufcspin);
1252 dirtybufspace -= bp->b_bufsize;
1253 if (bp->b_flags & B_HEAVY) {
1255 dirtybufspacehw -= bp->b_bufsize;
1257 spin_unlock(&bufcspin);
1259 bd_signal(bp->b_bufsize);
1262 * Since it is now being written, we can clear its deferred write flag.
1264 bp->b_flags &= ~B_DEFERRED;
1268 * Set the b_runningbufspace field, used to track how much I/O is
1269 * in progress at any given moment.
1272 bsetrunningbufspace(struct buf *bp, int bytes)
1274 bp->b_runningbufspace = bytes;
1276 spin_lock(&bufcspin);
1277 runningbufspace += bytes;
1279 spin_unlock(&bufcspin);
1286 * Release a busy buffer and, if requested, free its resources. The
1287 * buffer will be stashed in the appropriate bufqueue[] allowing it
1288 * to be accessed later as a cache entity or reused for other purposes.
1293 brelse(struct buf *bp)
1296 int saved_flags = bp->b_flags;
1299 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)), ("brelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp));
1302 * If B_NOCACHE is set we are being asked to destroy the buffer and
1303 * its backing store. Clear B_DELWRI.
1305 * B_NOCACHE is set in two cases: (1) when the caller really wants
1306 * to destroy the buffer and backing store and (2) when the caller
1307 * wants to destroy the buffer and backing store after a write
1310 if ((bp->b_flags & (B_NOCACHE|B_DELWRI)) == (B_NOCACHE|B_DELWRI)) {
1314 if ((bp->b_flags & (B_INVAL | B_DELWRI)) == B_DELWRI) {
1316 * A re-dirtied buffer is only subject to destruction
1317 * by B_INVAL. B_ERROR and B_NOCACHE are ignored.
1319 /* leave buffer intact */
1320 } else if ((bp->b_flags & (B_NOCACHE | B_INVAL | B_ERROR)) ||
1321 (bp->b_bufsize <= 0)) {
1323 * Either a failed read or we were asked to free or not
1324 * cache the buffer. This path is reached with B_DELWRI
1325 * set only if B_INVAL is already set. B_NOCACHE governs
1326 * backing store destruction.
1328 * NOTE: HAMMER will set B_LOCKED in buf_deallocate if the
1329 * buffer cannot be immediately freed.
1331 bp->b_flags |= B_INVAL;
1332 if (LIST_FIRST(&bp->b_dep) != NULL)
1334 if (bp->b_flags & B_DELWRI) {
1335 spin_lock(&bufcspin);
1337 dirtybufspace -= bp->b_bufsize;
1338 if (bp->b_flags & B_HEAVY) {
1340 dirtybufspacehw -= bp->b_bufsize;
1342 spin_unlock(&bufcspin);
1344 bd_signal(bp->b_bufsize);
1346 bp->b_flags &= ~(B_DELWRI | B_CACHE);
1350 * We must clear B_RELBUF if B_DELWRI or B_LOCKED is set.
1351 * If vfs_vmio_release() is called with either bit set, the
1352 * underlying pages may wind up getting freed causing a previous
1353 * write (bdwrite()) to get 'lost' because pages associated with
1354 * a B_DELWRI bp are marked clean. Pages associated with a
1355 * B_LOCKED buffer may be mapped by the filesystem.
1357 * If we want to release the buffer ourselves (rather then the
1358 * originator asking us to release it), give the originator a
1359 * chance to countermand the release by setting B_LOCKED.
1361 * We still allow the B_INVAL case to call vfs_vmio_release(), even
1362 * if B_DELWRI is set.
1364 * If B_DELWRI is not set we may have to set B_RELBUF if we are low
1365 * on pages to return pages to the VM page queues.
1367 if (bp->b_flags & (B_DELWRI | B_LOCKED)) {
1368 bp->b_flags &= ~B_RELBUF;
1369 } else if (vm_page_count_severe()) {
1370 if (LIST_FIRST(&bp->b_dep) != NULL)
1371 buf_deallocate(bp); /* can set B_LOCKED */
1372 if (bp->b_flags & (B_DELWRI | B_LOCKED))
1373 bp->b_flags &= ~B_RELBUF;
1375 bp->b_flags |= B_RELBUF;
1379 * Make sure b_cmd is clear. It may have already been cleared by
1382 * At this point destroying the buffer is governed by the B_INVAL
1383 * or B_RELBUF flags.
1385 bp->b_cmd = BUF_CMD_DONE;
1386 dsched_exit_buf(bp);
1389 * VMIO buffer rundown. Make sure the VM page array is restored
1390 * after an I/O may have replaces some of the pages with bogus pages
1391 * in order to not destroy dirty pages in a fill-in read.
1393 * Note that due to the code above, if a buffer is marked B_DELWRI
1394 * then the B_RELBUF and B_NOCACHE bits will always be clear.
1395 * B_INVAL may still be set, however.
1397 * For clean buffers, B_INVAL or B_RELBUF will destroy the buffer
1398 * but not the backing store. B_NOCACHE will destroy the backing
1401 * Note that dirty NFS buffers contain byte-granular write ranges
1402 * and should not be destroyed w/ B_INVAL even if the backing store
1405 if (bp->b_flags & B_VMIO) {
1407 * Rundown for VMIO buffers which are not dirty NFS buffers.
1419 * Get the base offset and length of the buffer. Note that
1420 * in the VMIO case if the buffer block size is not
1421 * page-aligned then b_data pointer may not be page-aligned.
1422 * But our b_xio.xio_pages array *IS* page aligned.
1424 * block sizes less then DEV_BSIZE (usually 512) are not
1425 * supported due to the page granularity bits (m->valid,
1426 * m->dirty, etc...).
1428 * See man buf(9) for more information
1431 resid = bp->b_bufsize;
1432 foff = bp->b_loffset;
1434 lwkt_gettoken(&vm_token);
1435 for (i = 0; i < bp->b_xio.xio_npages; i++) {
1436 m = bp->b_xio.xio_pages[i];
1437 vm_page_flag_clear(m, PG_ZERO);
1439 * If we hit a bogus page, fixup *all* of them
1440 * now. Note that we left these pages wired
1441 * when we removed them so they had better exist,
1442 * and they cannot be ripped out from under us so
1443 * no critical section protection is necessary.
1445 if (m == bogus_page) {
1447 poff = OFF_TO_IDX(bp->b_loffset);
1449 for (j = i; j < bp->b_xio.xio_npages; j++) {
1452 mtmp = bp->b_xio.xio_pages[j];
1453 if (mtmp == bogus_page) {
1454 mtmp = vm_page_lookup(obj, poff + j);
1456 panic("brelse: page missing");
1458 bp->b_xio.xio_pages[j] = mtmp;
1461 bp->b_flags &= ~B_HASBOGUS;
1463 if ((bp->b_flags & B_INVAL) == 0) {
1464 pmap_qenter(trunc_page((vm_offset_t)bp->b_data),
1465 bp->b_xio.xio_pages, bp->b_xio.xio_npages);
1467 m = bp->b_xio.xio_pages[i];
1471 * Invalidate the backing store if B_NOCACHE is set
1472 * (e.g. used with vinvalbuf()). If this is NFS
1473 * we impose a requirement that the block size be
1474 * a multiple of PAGE_SIZE and create a temporary
1475 * hack to basically invalidate the whole page. The
1476 * problem is that NFS uses really odd buffer sizes
1477 * especially when tracking piecemeal writes and
1478 * it also vinvalbuf()'s a lot, which would result
1479 * in only partial page validation and invalidation
1480 * here. If the file page is mmap()'d, however,
1481 * all the valid bits get set so after we invalidate
1482 * here we would end up with weird m->valid values
1483 * like 0xfc. nfs_getpages() can't handle this so
1484 * we clear all the valid bits for the NFS case
1485 * instead of just some of them.
1487 * The real bug is the VM system having to set m->valid
1488 * to VM_PAGE_BITS_ALL for faulted-in pages, which
1489 * itself is an artifact of the whole 512-byte
1490 * granular mess that exists to support odd block
1491 * sizes and UFS meta-data block sizes (e.g. 6144).
1492 * A complete rewrite is required.
1496 if (bp->b_flags & (B_NOCACHE|B_ERROR)) {
1497 int poffset = foff & PAGE_MASK;
1500 presid = PAGE_SIZE - poffset;
1501 if (bp->b_vp->v_tag == VT_NFS &&
1502 bp->b_vp->v_type == VREG) {
1504 } else if (presid > resid) {
1507 KASSERT(presid >= 0, ("brelse: extra page"));
1508 vm_page_set_invalid(m, poffset, presid);
1511 * Also make sure any swap cache is removed
1512 * as it is now stale (HAMMER in particular
1513 * uses B_NOCACHE to deal with buffer
1516 swap_pager_unswapped(m);
1518 resid -= PAGE_SIZE - (foff & PAGE_MASK);
1519 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK;
1521 if (bp->b_flags & (B_INVAL | B_RELBUF))
1522 vfs_vmio_release(bp);
1523 lwkt_reltoken(&vm_token);
1526 * Rundown for non-VMIO buffers.
1528 if (bp->b_flags & (B_INVAL | B_RELBUF)) {
1531 KKASSERT (LIST_FIRST(&bp->b_dep) == NULL);
1537 if (bp->b_qindex != BQUEUE_NONE)
1538 panic("brelse: free buffer onto another queue???");
1539 if (BUF_REFCNTNB(bp) > 1) {
1540 /* Temporary panic to verify exclusive locking */
1541 /* This panic goes away when we allow shared refs */
1542 panic("brelse: multiple refs");
1548 * Figure out the correct queue to place the cleaned up buffer on.
1549 * Buffers placed in the EMPTY or EMPTYKVA had better already be
1550 * disassociated from their vnode.
1552 spin_lock(&bufqspin);
1553 if (bp->b_flags & B_LOCKED) {
1555 * Buffers that are locked are placed in the locked queue
1556 * immediately, regardless of their state.
1558 bp->b_qindex = BQUEUE_LOCKED;
1559 TAILQ_INSERT_TAIL(&bufqueues[BQUEUE_LOCKED], bp, b_freelist);
1560 } else if (bp->b_bufsize == 0) {
1562 * Buffers with no memory. Due to conditionals near the top
1563 * of brelse() such buffers should probably already be
1564 * marked B_INVAL and disassociated from their vnode.
1566 bp->b_flags |= B_INVAL;
1567 KASSERT(bp->b_vp == NULL, ("bp1 %p flags %08x/%08x vnode %p unexpectededly still associated!", bp, saved_flags, bp->b_flags, bp->b_vp));
1568 KKASSERT((bp->b_flags & B_HASHED) == 0);
1569 if (bp->b_kvasize) {
1570 bp->b_qindex = BQUEUE_EMPTYKVA;
1572 bp->b_qindex = BQUEUE_EMPTY;
1574 TAILQ_INSERT_HEAD(&bufqueues[bp->b_qindex], bp, b_freelist);
1575 } else if (bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF)) {
1577 * Buffers with junk contents. Again these buffers had better
1578 * already be disassociated from their vnode.
1580 KASSERT(bp->b_vp == NULL, ("bp2 %p flags %08x/%08x vnode %p unexpectededly still associated!", bp, saved_flags, bp->b_flags, bp->b_vp));
1581 KKASSERT((bp->b_flags & B_HASHED) == 0);
1582 bp->b_flags |= B_INVAL;
1583 bp->b_qindex = BQUEUE_CLEAN;
1584 TAILQ_INSERT_HEAD(&bufqueues[BQUEUE_CLEAN], bp, b_freelist);
1587 * Remaining buffers. These buffers are still associated with
1590 switch(bp->b_flags & (B_DELWRI|B_HEAVY)) {
1592 bp->b_qindex = BQUEUE_DIRTY;
1593 TAILQ_INSERT_TAIL(&bufqueues[BQUEUE_DIRTY], bp, b_freelist);
1595 case B_DELWRI | B_HEAVY:
1596 bp->b_qindex = BQUEUE_DIRTY_HW;
1597 TAILQ_INSERT_TAIL(&bufqueues[BQUEUE_DIRTY_HW], bp,
1602 * NOTE: Buffers are always placed at the end of the
1603 * queue. If B_AGE is not set the buffer will cycle
1604 * through the queue twice.
1606 bp->b_qindex = BQUEUE_CLEAN;
1607 TAILQ_INSERT_TAIL(&bufqueues[BQUEUE_CLEAN], bp, b_freelist);
1611 spin_unlock(&bufqspin);
1614 * If B_INVAL, clear B_DELWRI. We've already placed the buffer
1615 * on the correct queue.
1617 if ((bp->b_flags & (B_INVAL|B_DELWRI)) == (B_INVAL|B_DELWRI))
1621 * The bp is on an appropriate queue unless locked. If it is not
1622 * locked or dirty we can wakeup threads waiting for buffer space.
1624 * We've already handled the B_INVAL case ( B_DELWRI will be clear
1625 * if B_INVAL is set ).
1627 if ((bp->b_flags & (B_LOCKED|B_DELWRI)) == 0)
1631 * Something we can maybe free or reuse
1633 if (bp->b_bufsize || bp->b_kvasize)
1637 * Clean up temporary flags and unlock the buffer.
1639 bp->b_flags &= ~(B_ORDERED | B_NOCACHE | B_RELBUF | B_DIRECT);
1646 * Release a buffer back to the appropriate queue but do not try to free
1647 * it. The buffer is expected to be used again soon.
1649 * bqrelse() is used by bdwrite() to requeue a delayed write, and used by
1650 * biodone() to requeue an async I/O on completion. It is also used when
1651 * known good buffers need to be requeued but we think we may need the data
1654 * XXX we should be able to leave the B_RELBUF hint set on completion.
1659 bqrelse(struct buf *bp)
1661 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)), ("bqrelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp));
1663 if (bp->b_qindex != BQUEUE_NONE)
1664 panic("bqrelse: free buffer onto another queue???");
1665 if (BUF_REFCNTNB(bp) > 1) {
1666 /* do not release to free list */
1667 panic("bqrelse: multiple refs");
1671 buf_act_advance(bp);
1673 spin_lock(&bufqspin);
1674 if (bp->b_flags & B_LOCKED) {
1676 * Locked buffers are released to the locked queue. However,
1677 * if the buffer is dirty it will first go into the dirty
1678 * queue and later on after the I/O completes successfully it
1679 * will be released to the locked queue.
1681 bp->b_qindex = BQUEUE_LOCKED;
1682 TAILQ_INSERT_TAIL(&bufqueues[BQUEUE_LOCKED], bp, b_freelist);
1683 } else if (bp->b_flags & B_DELWRI) {
1684 bp->b_qindex = (bp->b_flags & B_HEAVY) ?
1685 BQUEUE_DIRTY_HW : BQUEUE_DIRTY;
1686 TAILQ_INSERT_TAIL(&bufqueues[bp->b_qindex], bp, b_freelist);
1687 } else if (vm_page_count_severe()) {
1689 * We are too low on memory, we have to try to free the
1690 * buffer (most importantly: the wired pages making up its
1691 * backing store) *now*.
1693 spin_unlock(&bufqspin);
1697 bp->b_qindex = BQUEUE_CLEAN;
1698 TAILQ_INSERT_TAIL(&bufqueues[BQUEUE_CLEAN], bp, b_freelist);
1700 spin_unlock(&bufqspin);
1702 if ((bp->b_flags & B_LOCKED) == 0 &&
1703 ((bp->b_flags & B_INVAL) || (bp->b_flags & B_DELWRI) == 0)) {
1708 * Something we can maybe free or reuse.
1710 if (bp->b_bufsize && !(bp->b_flags & B_DELWRI))
1714 * Final cleanup and unlock. Clear bits that are only used while a
1715 * buffer is actively locked.
1717 bp->b_flags &= ~(B_ORDERED | B_NOCACHE | B_RELBUF);
1718 dsched_exit_buf(bp);
1725 * Return backing pages held by the buffer 'bp' back to the VM system
1726 * if possible. The pages are freed if they are no longer valid or
1727 * attempt to free if it was used for direct I/O otherwise they are
1728 * sent to the page cache.
1730 * Pages that were marked busy are left alone and skipped.
1732 * The KVA mapping (b_data) for the underlying pages is removed by
1736 vfs_vmio_release(struct buf *bp)
1741 lwkt_gettoken(&vm_token);
1742 for (i = 0; i < bp->b_xio.xio_npages; i++) {
1743 m = bp->b_xio.xio_pages[i];
1744 bp->b_xio.xio_pages[i] = NULL;
1747 * The VFS is telling us this is not a meta-data buffer
1748 * even if it is backed by a block device.
1750 if (bp->b_flags & B_NOTMETA)
1751 vm_page_flag_set(m, PG_NOTMETA);
1754 * This is a very important bit of code. We try to track
1755 * VM page use whether the pages are wired into the buffer
1756 * cache or not. While wired into the buffer cache the
1757 * bp tracks the act_count.
1759 * We can choose to place unwired pages on the inactive
1760 * queue (0) or active queue (1). If we place too many
1761 * on the active queue the queue will cycle the act_count
1762 * on pages we'd like to keep, just from single-use pages
1763 * (such as when doing a tar-up or file scan).
1765 if (bp->b_act_count < vm_cycle_point)
1766 vm_page_unwire(m, 0);
1768 vm_page_unwire(m, 1);
1771 * We don't mess with busy pages, it is the responsibility
1772 * of the process that busied the pages to deal with them.
1774 * However, the caller may have marked the page invalid and
1775 * we must still make sure the page is no longer mapped.
1777 if ((m->flags & PG_BUSY) || (m->busy != 0)) {
1778 vm_page_protect(m, VM_PROT_NONE);
1782 if (m->wire_count == 0) {
1783 vm_page_flag_clear(m, PG_ZERO);
1785 * Might as well free the page if we can and it has
1786 * no valid data. We also free the page if the
1787 * buffer was used for direct I/O.
1790 if ((bp->b_flags & B_ASYNC) == 0 && !m->valid &&
1791 m->hold_count == 0) {
1793 vm_page_protect(m, VM_PROT_NONE);
1797 if (bp->b_flags & B_DIRECT) {
1798 vm_page_try_to_free(m);
1799 } else if (vm_page_count_severe()) {
1800 m->act_count = bp->b_act_count;
1801 vm_page_try_to_cache(m);
1803 m->act_count = bp->b_act_count;
1807 lwkt_reltoken(&vm_token);
1809 pmap_qremove(trunc_page((vm_offset_t) bp->b_data),
1810 bp->b_xio.xio_npages);
1811 if (bp->b_bufsize) {
1815 bp->b_xio.xio_npages = 0;
1816 bp->b_flags &= ~B_VMIO;
1817 KKASSERT (LIST_FIRST(&bp->b_dep) == NULL);
1825 * Implement clustered async writes for clearing out B_DELWRI buffers.
1826 * This is much better then the old way of writing only one buffer at
1827 * a time. Note that we may not be presented with the buffers in the
1828 * correct order, so we search for the cluster in both directions.
1830 * The buffer is locked on call.
1833 vfs_bio_awrite(struct buf *bp)
1837 off_t loffset = bp->b_loffset;
1838 struct vnode *vp = bp->b_vp;
1845 * right now we support clustered writing only to regular files. If
1846 * we find a clusterable block we could be in the middle of a cluster
1847 * rather then at the beginning.
1849 * NOTE: b_bio1 contains the logical loffset and is aliased
1850 * to b_loffset. b_bio2 contains the translated block number.
1852 if ((vp->v_type == VREG) &&
1853 (vp->v_mount != 0) && /* Only on nodes that have the size info */
1854 (bp->b_flags & (B_CLUSTEROK | B_INVAL)) == B_CLUSTEROK) {
1856 size = vp->v_mount->mnt_stat.f_iosize;
1858 for (i = size; i < MAXPHYS; i += size) {
1859 if ((bpa = findblk(vp, loffset + i, FINDBLK_TEST)) &&
1860 BUF_REFCNT(bpa) == 0 &&
1861 ((bpa->b_flags & (B_DELWRI | B_CLUSTEROK | B_INVAL)) ==
1862 (B_DELWRI | B_CLUSTEROK)) &&
1863 (bpa->b_bufsize == size)) {
1864 if ((bpa->b_bio2.bio_offset == NOOFFSET) ||
1865 (bpa->b_bio2.bio_offset !=
1866 bp->b_bio2.bio_offset + i))
1872 for (j = size; i + j <= MAXPHYS && j <= loffset; j += size) {
1873 if ((bpa = findblk(vp, loffset - j, FINDBLK_TEST)) &&
1874 BUF_REFCNT(bpa) == 0 &&
1875 ((bpa->b_flags & (B_DELWRI | B_CLUSTEROK | B_INVAL)) ==
1876 (B_DELWRI | B_CLUSTEROK)) &&
1877 (bpa->b_bufsize == size)) {
1878 if ((bpa->b_bio2.bio_offset == NOOFFSET) ||
1879 (bpa->b_bio2.bio_offset !=
1880 bp->b_bio2.bio_offset - j))
1890 * this is a possible cluster write
1892 if (nbytes != size) {
1894 nwritten = cluster_wbuild(vp, size,
1895 loffset - j, nbytes);
1901 * default (old) behavior, writing out only one block
1903 * XXX returns b_bufsize instead of b_bcount for nwritten?
1905 nwritten = bp->b_bufsize;
1915 * Find and initialize a new buffer header, freeing up existing buffers
1916 * in the bufqueues as necessary. The new buffer is returned locked.
1918 * Important: B_INVAL is not set. If the caller wishes to throw the
1919 * buffer away, the caller must set B_INVAL prior to calling brelse().
1922 * We have insufficient buffer headers
1923 * We have insufficient buffer space
1924 * buffer_map is too fragmented ( space reservation fails )
1925 * If we have to flush dirty buffers ( but we try to avoid this )
1927 * To avoid VFS layer recursion we do not flush dirty buffers ourselves.
1928 * Instead we ask the buf daemon to do it for us. We attempt to
1929 * avoid piecemeal wakeups of the pageout daemon.
1934 getnewbuf(int blkflags, int slptimeo, int size, int maxsize)
1940 int slpflags = (blkflags & GETBLK_PCATCH) ? PCATCH : 0;
1941 static int flushingbufs;
1944 * We can't afford to block since we might be holding a vnode lock,
1945 * which may prevent system daemons from running. We deal with
1946 * low-memory situations by proactively returning memory and running
1947 * async I/O rather then sync I/O.
1951 --getnewbufrestarts;
1953 ++getnewbufrestarts;
1956 * Setup for scan. If we do not have enough free buffers,
1957 * we setup a degenerate case that immediately fails. Note
1958 * that if we are specially marked process, we are allowed to
1959 * dip into our reserves.
1961 * The scanning sequence is nominally: EMPTY->EMPTYKVA->CLEAN
1963 * We start with EMPTYKVA. If the list is empty we backup to EMPTY.
1964 * However, there are a number of cases (defragging, reusing, ...)
1965 * where we cannot backup.
1967 nqindex = BQUEUE_EMPTYKVA;
1968 spin_lock(&bufqspin);
1969 nbp = TAILQ_FIRST(&bufqueues[BQUEUE_EMPTYKVA]);
1973 * If no EMPTYKVA buffers and we are either
1974 * defragging or reusing, locate a CLEAN buffer
1975 * to free or reuse. If bufspace useage is low
1976 * skip this step so we can allocate a new buffer.
1978 if (defrag || bufspace >= lobufspace) {
1979 nqindex = BQUEUE_CLEAN;
1980 nbp = TAILQ_FIRST(&bufqueues[BQUEUE_CLEAN]);
1984 * If we could not find or were not allowed to reuse a
1985 * CLEAN buffer, check to see if it is ok to use an EMPTY
1986 * buffer. We can only use an EMPTY buffer if allocating
1987 * its KVA would not otherwise run us out of buffer space.
1989 if (nbp == NULL && defrag == 0 &&
1990 bufspace + maxsize < hibufspace) {
1991 nqindex = BQUEUE_EMPTY;
1992 nbp = TAILQ_FIRST(&bufqueues[BQUEUE_EMPTY]);
1997 * Run scan, possibly freeing data and/or kva mappings on the fly
2000 * WARNING! bufqspin is held!
2002 while ((bp = nbp) != NULL) {
2003 int qindex = nqindex;
2005 nbp = TAILQ_NEXT(bp, b_freelist);
2008 * BQUEUE_CLEAN - B_AGE special case. If not set the bp
2009 * cycles through the queue twice before being selected.
2011 if (qindex == BQUEUE_CLEAN &&
2012 (bp->b_flags & B_AGE) == 0 && nbp) {
2013 bp->b_flags |= B_AGE;
2014 TAILQ_REMOVE(&bufqueues[qindex], bp, b_freelist);
2015 TAILQ_INSERT_TAIL(&bufqueues[qindex], bp, b_freelist);
2020 * Calculate next bp ( we can only use it if we do not block
2021 * or do other fancy things ).
2026 nqindex = BQUEUE_EMPTYKVA;
2027 if ((nbp = TAILQ_FIRST(&bufqueues[BQUEUE_EMPTYKVA])))
2030 case BQUEUE_EMPTYKVA:
2031 nqindex = BQUEUE_CLEAN;
2032 if ((nbp = TAILQ_FIRST(&bufqueues[BQUEUE_CLEAN])))
2046 KASSERT(bp->b_qindex == qindex,
2047 ("getnewbuf: inconsistent queue %d bp %p", qindex, bp));
2050 * Note: we no longer distinguish between VMIO and non-VMIO
2053 KASSERT((bp->b_flags & B_DELWRI) == 0,
2054 ("delwri buffer %p found in queue %d", bp, qindex));
2057 * Do not try to reuse a buffer with a non-zero b_refs.
2058 * This is an unsynchronized test. A synchronized test
2059 * is also performed after we lock the buffer.
2065 * If we are defragging then we need a buffer with
2066 * b_kvasize != 0. XXX this situation should no longer
2067 * occur, if defrag is non-zero the buffer's b_kvasize
2068 * should also be non-zero at this point. XXX
2070 if (defrag && bp->b_kvasize == 0) {
2071 kprintf("Warning: defrag empty buffer %p\n", bp);
2076 * Start freeing the bp. This is somewhat involved. nbp
2077 * remains valid only for BQUEUE_EMPTY[KVA] bp's. Buffers
2078 * on the clean list must be disassociated from their
2079 * current vnode. Buffers on the empty[kva] lists have
2080 * already been disassociated.
2083 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT) != 0) {
2084 spin_unlock(&bufqspin);
2085 tsleep(&bd_request, 0, "gnbxxx", (hz + 99) / 100);
2088 if (bp->b_qindex != qindex) {
2089 spin_unlock(&bufqspin);
2090 kprintf("getnewbuf: warning, BUF_LOCK blocked "
2091 "unexpectedly on buf %p index %d->%d, "
2093 bp, qindex, bp->b_qindex);
2097 bremfree_locked(bp);
2098 spin_unlock(&bufqspin);
2101 * Dependancies must be handled before we disassociate the
2104 * NOTE: HAMMER will set B_LOCKED if the buffer cannot
2105 * be immediately disassociated. HAMMER then becomes
2106 * responsible for releasing the buffer.
2108 * NOTE: bufqspin is UNLOCKED now.
2110 if (LIST_FIRST(&bp->b_dep) != NULL) {
2112 if (bp->b_flags & B_LOCKED) {
2116 KKASSERT(LIST_FIRST(&bp->b_dep) == NULL);
2119 if (qindex == BQUEUE_CLEAN) {
2120 if (bp->b_flags & B_VMIO)
2121 vfs_vmio_release(bp);
2127 * NOTE: nbp is now entirely invalid. We can only restart
2128 * the scan from this point on.
2130 * Get the rest of the buffer freed up. b_kva* is still
2131 * valid after this operation.
2134 KASSERT(bp->b_vp == NULL, ("bp3 %p flags %08x vnode %p qindex %d unexpectededly still associated!", bp, bp->b_flags, bp->b_vp, qindex));
2135 KKASSERT((bp->b_flags & B_HASHED) == 0);
2138 * critical section protection is not required when
2139 * scrapping a buffer's contents because it is already
2145 bp->b_flags = B_BNOCLIP;
2146 bp->b_cmd = BUF_CMD_DONE;
2151 bp->b_xio.xio_npages = 0;
2152 bp->b_dirtyoff = bp->b_dirtyend = 0;
2153 bp->b_act_count = ACT_INIT;
2155 KKASSERT(LIST_FIRST(&bp->b_dep) == NULL);
2157 if (blkflags & GETBLK_BHEAVY)
2158 bp->b_flags |= B_HEAVY;
2161 * If we are defragging then free the buffer.
2164 bp->b_flags |= B_INVAL;
2172 * If we are overcomitted then recover the buffer and its
2173 * KVM space. This occurs in rare situations when multiple
2174 * processes are blocked in getnewbuf() or allocbuf().
2176 if (bufspace >= hibufspace)
2178 if (flushingbufs && bp->b_kvasize != 0) {
2179 bp->b_flags |= B_INVAL;
2184 if (bufspace < lobufspace)
2188 * The brelvp() above interlocked the buffer, test b_refs
2189 * to determine if the buffer can be reused. b_refs
2190 * interlocks lookup/blocking-lock operations and allowing
2191 * buffer reuse can create deadlocks depending on what
2192 * (vp,loffset) is assigned to the reused buffer (see getblk).
2195 bp->b_flags |= B_INVAL;
2202 /* NOT REACHED, bufqspin not held */
2206 * If we exhausted our list, sleep as appropriate. We may have to
2207 * wakeup various daemons and write out some dirty buffers.
2209 * Generally we are sleeping due to insufficient buffer space.
2211 * NOTE: bufqspin is held if bp is NULL, else it is not held.
2217 spin_unlock(&bufqspin);
2219 flags = VFS_BIO_NEED_BUFSPACE;
2221 } else if (bufspace >= hibufspace) {
2223 flags = VFS_BIO_NEED_BUFSPACE;
2226 flags = VFS_BIO_NEED_ANY;
2229 bd_speedup(); /* heeeelp */
2230 spin_lock(&bufcspin);
2231 needsbuffer |= flags;
2232 while (needsbuffer & flags) {
2233 if (ssleep(&needsbuffer, &bufcspin,
2234 slpflags, waitmsg, slptimeo)) {
2235 spin_unlock(&bufcspin);
2239 spin_unlock(&bufcspin);
2242 * We finally have a valid bp. We aren't quite out of the
2243 * woods, we still have to reserve kva space. In order
2244 * to keep fragmentation sane we only allocate kva in
2247 * (bufqspin is not held)
2249 maxsize = (maxsize + BKVAMASK) & ~BKVAMASK;
2251 if (maxsize != bp->b_kvasize) {
2252 vm_offset_t addr = 0;
2257 count = vm_map_entry_reserve(MAP_RESERVE_COUNT);
2258 vm_map_lock(&buffer_map);
2260 if (vm_map_findspace(&buffer_map,
2261 vm_map_min(&buffer_map), maxsize,
2262 maxsize, 0, &addr)) {
2264 * Uh oh. Buffer map is too fragmented. We
2265 * must defragment the map.
2267 vm_map_unlock(&buffer_map);
2268 vm_map_entry_release(count);
2271 bp->b_flags |= B_INVAL;
2276 vm_map_insert(&buffer_map, &count,
2278 addr, addr + maxsize,
2280 VM_PROT_ALL, VM_PROT_ALL,
2283 bp->b_kvabase = (caddr_t) addr;
2284 bp->b_kvasize = maxsize;
2285 bufspace += bp->b_kvasize;
2288 vm_map_unlock(&buffer_map);
2289 vm_map_entry_release(count);
2291 bp->b_data = bp->b_kvabase;
2297 * This routine is called in an emergency to recover VM pages from the
2298 * buffer cache by cashing in clean buffers. The idea is to recover
2299 * enough pages to be able to satisfy a stuck bio_page_alloc().
2304 recoverbufpages(void)
2311 spin_lock(&bufqspin);
2312 while (bytes < MAXBSIZE) {
2313 bp = TAILQ_FIRST(&bufqueues[BQUEUE_CLEAN]);
2318 * BQUEUE_CLEAN - B_AGE special case. If not set the bp
2319 * cycles through the queue twice before being selected.
2321 if ((bp->b_flags & B_AGE) == 0 && TAILQ_NEXT(bp, b_freelist)) {
2322 bp->b_flags |= B_AGE;
2323 TAILQ_REMOVE(&bufqueues[BQUEUE_CLEAN], bp, b_freelist);
2324 TAILQ_INSERT_TAIL(&bufqueues[BQUEUE_CLEAN],
2332 KKASSERT(bp->b_qindex == BQUEUE_CLEAN);
2333 KKASSERT((bp->b_flags & B_DELWRI) == 0);
2336 * Start freeing the bp. This is somewhat involved.
2338 * Buffers on the clean list must be disassociated from
2339 * their current vnode
2342 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT) != 0) {
2343 kprintf("recoverbufpages: warning, locked buf %p, "
2346 ssleep(&bd_request, &bufqspin, 0, "gnbxxx", hz / 100);
2349 if (bp->b_qindex != BQUEUE_CLEAN) {
2350 kprintf("recoverbufpages: warning, BUF_LOCK blocked "
2351 "unexpectedly on buf %p index %d, race "
2357 bremfree_locked(bp);
2358 spin_unlock(&bufqspin);
2361 * Dependancies must be handled before we disassociate the
2364 * NOTE: HAMMER will set B_LOCKED if the buffer cannot
2365 * be immediately disassociated. HAMMER then becomes
2366 * responsible for releasing the buffer.
2368 if (LIST_FIRST(&bp->b_dep) != NULL) {
2370 if (bp->b_flags & B_LOCKED) {
2372 spin_lock(&bufqspin);
2375 KKASSERT(LIST_FIRST(&bp->b_dep) == NULL);
2378 bytes += bp->b_bufsize;
2380 if (bp->b_flags & B_VMIO) {
2381 bp->b_flags |= B_DIRECT; /* try to free pages */
2382 vfs_vmio_release(bp);
2387 KKASSERT(bp->b_vp == NULL);
2388 KKASSERT((bp->b_flags & B_HASHED) == 0);
2391 * critical section protection is not required when
2392 * scrapping a buffer's contents because it is already
2398 bp->b_flags = B_BNOCLIP;
2399 bp->b_cmd = BUF_CMD_DONE;
2404 bp->b_xio.xio_npages = 0;
2405 bp->b_dirtyoff = bp->b_dirtyend = 0;
2407 KKASSERT(LIST_FIRST(&bp->b_dep) == NULL);
2409 bp->b_flags |= B_INVAL;
2412 spin_lock(&bufqspin);
2414 spin_unlock(&bufqspin);
2421 * Buffer flushing daemon. Buffers are normally flushed by the
2422 * update daemon but if it cannot keep up this process starts to
2423 * take the load in an attempt to prevent getnewbuf() from blocking.
2425 * Once a flush is initiated it does not stop until the number
2426 * of buffers falls below lodirtybuffers, but we will wake up anyone
2427 * waiting at the mid-point.
2430 static struct kproc_desc buf_kp = {
2435 SYSINIT(bufdaemon, SI_SUB_KTHREAD_BUF, SI_ORDER_FIRST,
2436 kproc_start, &buf_kp)
2438 static struct kproc_desc bufhw_kp = {
2443 SYSINIT(bufdaemon_hw, SI_SUB_KTHREAD_BUF, SI_ORDER_FIRST,
2444 kproc_start, &bufhw_kp)
2455 * This process needs to be suspended prior to shutdown sync.
2457 EVENTHANDLER_REGISTER(shutdown_pre_sync, shutdown_kproc,
2458 bufdaemon_td, SHUTDOWN_PRI_LAST);
2459 curthread->td_flags |= TDF_SYSTHREAD;
2462 * This process is allowed to take the buffer cache to the limit
2465 kproc_suspend_loop();
2468 * Do the flush as long as the number of dirty buffers
2469 * (including those running) exceeds lodirtybufspace.
2471 * When flushing limit running I/O to hirunningspace
2472 * Do the flush. Limit the amount of in-transit I/O we
2473 * allow to build up, otherwise we would completely saturate
2474 * the I/O system. Wakeup any waiting processes before we
2475 * normally would so they can run in parallel with our drain.
2477 * Our aggregate normal+HW lo water mark is lodirtybufspace,
2478 * but because we split the operation into two threads we
2479 * have to cut it in half for each thread.
2481 waitrunningbufspace();
2482 limit = lodirtybufspace / 2;
2483 while (runningbufspace + dirtybufspace > limit ||
2484 dirtybufcount - dirtybufcounthw >= nbuf / 2) {
2485 if (flushbufqueues(BQUEUE_DIRTY) == 0)
2487 if (runningbufspace < hirunningspace)
2489 waitrunningbufspace();
2493 * We reached our low water mark, reset the
2494 * request and sleep until we are needed again.
2495 * The sleep is just so the suspend code works.
2497 spin_lock(&bufcspin);
2498 if (bd_request == 0)
2499 ssleep(&bd_request, &bufcspin, 0, "psleep", hz);
2501 spin_unlock(&bufcspin);
2514 * This process needs to be suspended prior to shutdown sync.
2516 EVENTHANDLER_REGISTER(shutdown_pre_sync, shutdown_kproc,
2517 bufdaemonhw_td, SHUTDOWN_PRI_LAST);
2518 curthread->td_flags |= TDF_SYSTHREAD;
2521 * This process is allowed to take the buffer cache to the limit
2524 kproc_suspend_loop();
2527 * Do the flush. Limit the amount of in-transit I/O we
2528 * allow to build up, otherwise we would completely saturate
2529 * the I/O system. Wakeup any waiting processes before we
2530 * normally would so they can run in parallel with our drain.
2532 * Once we decide to flush push the queued I/O up to
2533 * hirunningspace in order to trigger bursting by the bioq
2536 * Our aggregate normal+HW lo water mark is lodirtybufspace,
2537 * but because we split the operation into two threads we
2538 * have to cut it in half for each thread.
2540 waitrunningbufspace();
2541 limit = lodirtybufspace / 2;
2542 while (runningbufspace + dirtybufspacehw > limit ||
2543 dirtybufcounthw >= nbuf / 2) {
2544 if (flushbufqueues(BQUEUE_DIRTY_HW) == 0)
2546 if (runningbufspace < hirunningspace)
2548 waitrunningbufspace();
2552 * We reached our low water mark, reset the
2553 * request and sleep until we are needed again.
2554 * The sleep is just so the suspend code works.
2556 spin_lock(&bufcspin);
2557 if (bd_request_hw == 0)
2558 ssleep(&bd_request_hw, &bufcspin, 0, "psleep", hz);
2560 spin_unlock(&bufcspin);
2567 * Try to flush a buffer in the dirty queue. We must be careful to
2568 * free up B_INVAL buffers instead of write them, which NFS is
2569 * particularly sensitive to.
2571 * B_RELBUF may only be set by VFSs. We do set B_AGE to indicate
2572 * that we really want to try to get the buffer out and reuse it
2573 * due to the write load on the machine.
2575 * We must lock the buffer in order to check its validity before we
2576 * can mess with its contents. bufqspin isn't enough.
2579 flushbufqueues(bufq_type_t q)
2585 spin_lock(&bufqspin);
2588 bp = TAILQ_FIRST(&bufqueues[q]);
2590 if ((bp->b_flags & B_DELWRI) == 0) {
2591 kprintf("Unexpected clean buffer %p\n", bp);
2592 bp = TAILQ_NEXT(bp, b_freelist);
2595 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT)) {
2596 bp = TAILQ_NEXT(bp, b_freelist);
2599 KKASSERT(bp->b_qindex == q);
2602 * Must recheck B_DELWRI after successfully locking
2605 if ((bp->b_flags & B_DELWRI) == 0) {
2607 bp = TAILQ_NEXT(bp, b_freelist);
2611 if (bp->b_flags & B_INVAL) {
2613 spin_unlock(&bufqspin);
2620 spin_unlock(&bufqspin);
2623 if (LIST_FIRST(&bp->b_dep) != NULL &&
2624 (bp->b_flags & B_DEFERRED) == 0 &&
2625 buf_countdeps(bp, 0)) {
2626 spin_lock(&bufqspin);
2628 TAILQ_REMOVE(&bufqueues[q], bp, b_freelist);
2629 TAILQ_INSERT_TAIL(&bufqueues[q], bp, b_freelist);
2630 bp->b_flags |= B_DEFERRED;
2632 bp = TAILQ_FIRST(&bufqueues[q]);
2637 * If the buffer has a dependancy, buf_checkwrite() must
2638 * also return 0 for us to be able to initate the write.
2640 * If the buffer is flagged B_ERROR it may be requeued
2641 * over and over again, we try to avoid a live lock.
2643 * NOTE: buf_checkwrite is MPSAFE.
2645 if (LIST_FIRST(&bp->b_dep) != NULL && buf_checkwrite(bp)) {
2648 } else if (bp->b_flags & B_ERROR) {
2649 tsleep(bp, 0, "bioer", 1);
2650 bp->b_flags &= ~B_AGE;
2653 bp->b_flags |= B_AGE;
2660 spin_unlock(&bufqspin);
2667 * Returns true if no I/O is needed to access the associated VM object.
2668 * This is like findblk except it also hunts around in the VM system for
2671 * Note that we ignore vm_page_free() races from interrupts against our
2672 * lookup, since if the caller is not protected our return value will not
2673 * be any more valid then otherwise once we exit the critical section.
2676 inmem(struct vnode *vp, off_t loffset)
2679 vm_offset_t toff, tinc, size;
2682 if (findblk(vp, loffset, FINDBLK_TEST))
2684 if (vp->v_mount == NULL)
2686 if ((obj = vp->v_object) == NULL)
2690 if (size > vp->v_mount->mnt_stat.f_iosize)
2691 size = vp->v_mount->mnt_stat.f_iosize;
2693 for (toff = 0; toff < vp->v_mount->mnt_stat.f_iosize; toff += tinc) {
2694 lwkt_gettoken(&vm_token);
2695 m = vm_page_lookup(obj, OFF_TO_IDX(loffset + toff));
2696 lwkt_reltoken(&vm_token);
2700 if (tinc > PAGE_SIZE - ((toff + loffset) & PAGE_MASK))
2701 tinc = PAGE_SIZE - ((toff + loffset) & PAGE_MASK);
2702 if (vm_page_is_valid(m,
2703 (vm_offset_t) ((toff + loffset) & PAGE_MASK), tinc) == 0)
2712 * Locate and return the specified buffer. Unless flagged otherwise,
2713 * a locked buffer will be returned if it exists or NULL if it does not.
2715 * findblk()'d buffers are still on the bufqueues and if you intend
2716 * to use your (locked NON-TEST) buffer you need to bremfree(bp)
2717 * and possibly do other stuff to it.
2719 * FINDBLK_TEST - Do not lock the buffer. The caller is responsible
2720 * for locking the buffer and ensuring that it remains
2721 * the desired buffer after locking.
2723 * FINDBLK_NBLOCK - Lock the buffer non-blocking. If we are unable
2724 * to acquire the lock we return NULL, even if the
2727 * FINDBLK_REF - Returns the buffer ref'd, which prevents reuse
2728 * by getnewbuf() but does not prevent disassociation
2729 * while we are locked. Used to avoid deadlocks
2730 * against random (vp,loffset)s due to reassignment.
2732 * (0) - Lock the buffer blocking.
2737 findblk(struct vnode *vp, off_t loffset, int flags)
2742 lkflags = LK_EXCLUSIVE;
2743 if (flags & FINDBLK_NBLOCK)
2744 lkflags |= LK_NOWAIT;
2748 * Lookup. Ref the buf while holding v_token to prevent
2749 * reuse (but does not prevent diassociation).
2751 lwkt_gettoken(&vp->v_token);
2752 bp = buf_rb_hash_RB_LOOKUP(&vp->v_rbhash_tree, loffset);
2754 lwkt_reltoken(&vp->v_token);
2757 atomic_add_int(&bp->b_refs, 1);
2758 lwkt_reltoken(&vp->v_token);
2761 * If testing only break and return bp, do not lock.
2763 if (flags & FINDBLK_TEST)
2767 * Lock the buffer, return an error if the lock fails.
2768 * (only FINDBLK_NBLOCK can cause the lock to fail).
2770 if (BUF_LOCK(bp, lkflags)) {
2771 atomic_subtract_int(&bp->b_refs, 1);
2772 /* bp = NULL; not needed */
2777 * Revalidate the locked buf before allowing it to be
2780 if (bp->b_vp == vp && bp->b_loffset == loffset)
2782 atomic_subtract_int(&bp->b_refs, 1);
2789 if ((flags & FINDBLK_REF) == 0)
2790 atomic_subtract_int(&bp->b_refs, 1);
2795 unrefblk(struct buf *bp)
2797 atomic_subtract_int(&bp->b_refs, 1);
2803 * Similar to getblk() except only returns the buffer if it is
2804 * B_CACHE and requires no other manipulation. Otherwise NULL
2807 * If B_RAM is set the buffer might be just fine, but we return
2808 * NULL anyway because we want the code to fall through to the
2809 * cluster read. Otherwise read-ahead breaks.
2811 * If blksize is 0 the buffer cache buffer must already be fully
2814 * If blksize is non-zero getblk() will be used, allowing a buffer
2815 * to be reinstantiated from its VM backing store. The buffer must
2816 * still be fully cached after reinstantiation to be returned.
2819 getcacheblk(struct vnode *vp, off_t loffset, int blksize)
2824 bp = getblk(vp, loffset, blksize, 0, 0);
2826 if ((bp->b_flags & (B_INVAL | B_CACHE | B_RAM)) ==
2828 bp->b_flags &= ~B_AGE;
2835 bp = findblk(vp, loffset, 0);
2837 if ((bp->b_flags & (B_INVAL | B_CACHE | B_RAM)) ==
2839 bp->b_flags &= ~B_AGE;
2853 * Get a block given a specified block and offset into a file/device.
2854 * B_INVAL may or may not be set on return. The caller should clear
2855 * B_INVAL prior to initiating a READ.
2857 * IT IS IMPORTANT TO UNDERSTAND THAT IF YOU CALL GETBLK() AND B_CACHE
2858 * IS NOT SET, YOU MUST INITIALIZE THE RETURNED BUFFER, ISSUE A READ,
2859 * OR SET B_INVAL BEFORE RETIRING IT. If you retire a getblk'd buffer
2860 * without doing any of those things the system will likely believe
2861 * the buffer to be valid (especially if it is not B_VMIO), and the
2862 * next getblk() will return the buffer with B_CACHE set.
2864 * For a non-VMIO buffer, B_CACHE is set to the opposite of B_INVAL for
2865 * an existing buffer.
2867 * For a VMIO buffer, B_CACHE is modified according to the backing VM.
2868 * If getblk()ing a previously 0-sized invalid buffer, B_CACHE is set
2869 * and then cleared based on the backing VM. If the previous buffer is
2870 * non-0-sized but invalid, B_CACHE will be cleared.
2872 * If getblk() must create a new buffer, the new buffer is returned with
2873 * both B_INVAL and B_CACHE clear unless it is a VMIO buffer, in which
2874 * case it is returned with B_INVAL clear and B_CACHE set based on the
2877 * getblk() also forces a bwrite() for any B_DELWRI buffer whos
2878 * B_CACHE bit is clear.
2880 * What this means, basically, is that the caller should use B_CACHE to
2881 * determine whether the buffer is fully valid or not and should clear
2882 * B_INVAL prior to issuing a read. If the caller intends to validate
2883 * the buffer by loading its data area with something, the caller needs
2884 * to clear B_INVAL. If the caller does this without issuing an I/O,
2885 * the caller should set B_CACHE ( as an optimization ), else the caller
2886 * should issue the I/O and biodone() will set B_CACHE if the I/O was
2887 * a write attempt or if it was a successfull read. If the caller
2888 * intends to issue a READ, the caller must clear B_INVAL and B_ERROR
2889 * prior to issuing the READ. biodone() will *not* clear B_INVAL.
2893 * GETBLK_PCATCH - catch signal if blocked, can cause NULL return
2894 * GETBLK_BHEAVY - heavy-weight buffer cache buffer
2899 getblk(struct vnode *vp, off_t loffset, int size, int blkflags, int slptimeo)
2902 int slpflags = (blkflags & GETBLK_PCATCH) ? PCATCH : 0;
2906 if (size > MAXBSIZE)
2907 panic("getblk: size(%d) > MAXBSIZE(%d)", size, MAXBSIZE);
2908 if (vp->v_object == NULL)
2909 panic("getblk: vnode %p has no object!", vp);
2912 if ((bp = findblk(vp, loffset, FINDBLK_REF | FINDBLK_TEST)) != NULL) {
2914 * The buffer was found in the cache, but we need to lock it.
2915 * We must acquire a ref on the bp to prevent reuse, but
2916 * this will not prevent disassociation (brelvp()) so we
2917 * must recheck (vp,loffset) after acquiring the lock.
2919 * Without the ref the buffer could potentially be reused
2920 * before we acquire the lock and create a deadlock
2921 * situation between the thread trying to reuse the buffer
2922 * and us due to the fact that we would wind up blocking
2923 * on a random (vp,loffset).
2925 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT)) {
2926 if (blkflags & GETBLK_NOWAIT) {
2930 lkflags = LK_EXCLUSIVE | LK_SLEEPFAIL;
2931 if (blkflags & GETBLK_PCATCH)
2932 lkflags |= LK_PCATCH;
2933 error = BUF_TIMELOCK(bp, lkflags, "getblk", slptimeo);
2936 if (error == ENOLCK)
2940 /* buffer may have changed on us */
2945 * Once the buffer has been locked, make sure we didn't race
2946 * a buffer recyclement. Buffers that are no longer hashed
2947 * will have b_vp == NULL, so this takes care of that check
2950 if (bp->b_vp != vp || bp->b_loffset != loffset) {
2951 kprintf("Warning buffer %p (vp %p loffset %lld) "
2953 bp, vp, (long long)loffset);
2959 * If SZMATCH any pre-existing buffer must be of the requested
2960 * size or NULL is returned. The caller absolutely does not
2961 * want getblk() to bwrite() the buffer on a size mismatch.
2963 if ((blkflags & GETBLK_SZMATCH) && size != bp->b_bcount) {
2969 * All vnode-based buffers must be backed by a VM object.
2971 KKASSERT(bp->b_flags & B_VMIO);
2972 KKASSERT(bp->b_cmd == BUF_CMD_DONE);
2973 bp->b_flags &= ~B_AGE;
2976 * Make sure that B_INVAL buffers do not have a cached
2977 * block number translation.
2979 if ((bp->b_flags & B_INVAL) && (bp->b_bio2.bio_offset != NOOFFSET)) {
2980 kprintf("Warning invalid buffer %p (vp %p loffset %lld)"
2981 " did not have cleared bio_offset cache\n",
2982 bp, vp, (long long)loffset);
2983 clearbiocache(&bp->b_bio2);
2987 * The buffer is locked. B_CACHE is cleared if the buffer is
2990 if (bp->b_flags & B_INVAL)
2991 bp->b_flags &= ~B_CACHE;
2995 * Any size inconsistancy with a dirty buffer or a buffer
2996 * with a softupdates dependancy must be resolved. Resizing
2997 * the buffer in such circumstances can lead to problems.
2999 * Dirty or dependant buffers are written synchronously.
3000 * Other types of buffers are simply released and
3001 * reconstituted as they may be backed by valid, dirty VM
3002 * pages (but not marked B_DELWRI).
3004 * NFS NOTE: NFS buffers which straddle EOF are oddly-sized
3005 * and may be left over from a prior truncation (and thus
3006 * no longer represent the actual EOF point), so we
3007 * definitely do not want to B_NOCACHE the backing store.
3009 if (size != bp->b_bcount) {
3010 if (bp->b_flags & B_DELWRI) {
3011 bp->b_flags |= B_RELBUF;
3013 } else if (LIST_FIRST(&bp->b_dep)) {
3014 bp->b_flags |= B_RELBUF;
3017 bp->b_flags |= B_RELBUF;
3022 KKASSERT(size <= bp->b_kvasize);
3023 KASSERT(bp->b_loffset != NOOFFSET,
3024 ("getblk: no buffer offset"));
3027 * A buffer with B_DELWRI set and B_CACHE clear must
3028 * be committed before we can return the buffer in
3029 * order to prevent the caller from issuing a read
3030 * ( due to B_CACHE not being set ) and overwriting
3033 * Most callers, including NFS and FFS, need this to
3034 * operate properly either because they assume they
3035 * can issue a read if B_CACHE is not set, or because
3036 * ( for example ) an uncached B_DELWRI might loop due
3037 * to softupdates re-dirtying the buffer. In the latter
3038 * case, B_CACHE is set after the first write completes,
3039 * preventing further loops.
3041 * NOTE! b*write() sets B_CACHE. If we cleared B_CACHE
3042 * above while extending the buffer, we cannot allow the
3043 * buffer to remain with B_CACHE set after the write
3044 * completes or it will represent a corrupt state. To
3045 * deal with this we set B_NOCACHE to scrap the buffer
3048 * XXX Should this be B_RELBUF instead of B_NOCACHE?
3049 * I'm not even sure this state is still possible
3050 * now that getblk() writes out any dirty buffers
3053 * We might be able to do something fancy, like setting
3054 * B_CACHE in bwrite() except if B_DELWRI is already set,
3055 * so the below call doesn't set B_CACHE, but that gets real
3056 * confusing. This is much easier.
3059 if ((bp->b_flags & (B_CACHE|B_DELWRI)) == B_DELWRI) {
3060 kprintf("getblk: Warning, bp %p loff=%jx DELWRI set "
3061 "and CACHE clear, b_flags %08x\n",
3062 bp, (intmax_t)bp->b_loffset, bp->b_flags);
3063 bp->b_flags |= B_NOCACHE;
3069 * Buffer is not in-core, create new buffer. The buffer
3070 * returned by getnewbuf() is locked. Note that the returned
3071 * buffer is also considered valid (not marked B_INVAL).
3073 * Calculating the offset for the I/O requires figuring out
3074 * the block size. We use DEV_BSIZE for VBLK or VCHR and
3075 * the mount's f_iosize otherwise. If the vnode does not
3076 * have an associated mount we assume that the passed size is
3079 * Note that vn_isdisk() cannot be used here since it may
3080 * return a failure for numerous reasons. Note that the
3081 * buffer size may be larger then the block size (the caller
3082 * will use block numbers with the proper multiple). Beware
3083 * of using any v_* fields which are part of unions. In
3084 * particular, in DragonFly the mount point overloading
3085 * mechanism uses the namecache only and the underlying
3086 * directory vnode is not a special case.
3090 if (vp->v_type == VBLK || vp->v_type == VCHR)
3092 else if (vp->v_mount)
3093 bsize = vp->v_mount->mnt_stat.f_iosize;
3097 maxsize = size + (loffset & PAGE_MASK);
3098 maxsize = imax(maxsize, bsize);
3100 bp = getnewbuf(blkflags, slptimeo, size, maxsize);
3102 if (slpflags || slptimeo)
3108 * Atomically insert the buffer into the hash, so that it can
3109 * be found by findblk().
3111 * If bgetvp() returns non-zero a collision occured, and the
3112 * bp will not be associated with the vnode.
3114 * Make sure the translation layer has been cleared.
3116 bp->b_loffset = loffset;
3117 bp->b_bio2.bio_offset = NOOFFSET;
3118 /* bp->b_bio2.bio_next = NULL; */
3120 if (bgetvp(vp, bp, size)) {
3121 bp->b_flags |= B_INVAL;
3127 * All vnode-based buffers must be backed by a VM object.
3129 KKASSERT(vp->v_object != NULL);
3130 bp->b_flags |= B_VMIO;
3131 KKASSERT(bp->b_cmd == BUF_CMD_DONE);
3135 KKASSERT(dsched_is_clear_buf_priv(bp));
3142 * Reacquire a buffer that was previously released to the locked queue,
3143 * or reacquire a buffer which is interlocked by having bioops->io_deallocate
3144 * set B_LOCKED (which handles the acquisition race).
3146 * To this end, either B_LOCKED must be set or the dependancy list must be
3152 regetblk(struct buf *bp)
3154 KKASSERT((bp->b_flags & B_LOCKED) || LIST_FIRST(&bp->b_dep) != NULL);
3155 BUF_LOCK(bp, LK_EXCLUSIVE | LK_RETRY);
3162 * Get an empty, disassociated buffer of given size. The buffer is
3163 * initially set to B_INVAL.
3165 * critical section protection is not required for the allocbuf()
3166 * call because races are impossible here.
3176 maxsize = (size + BKVAMASK) & ~BKVAMASK;
3178 while ((bp = getnewbuf(0, 0, size, maxsize)) == 0)
3181 bp->b_flags |= B_INVAL; /* b_dep cleared by getnewbuf() */
3182 KKASSERT(dsched_is_clear_buf_priv(bp));
3190 * This code constitutes the buffer memory from either anonymous system
3191 * memory (in the case of non-VMIO operations) or from an associated
3192 * VM object (in the case of VMIO operations). This code is able to
3193 * resize a buffer up or down.
3195 * Note that this code is tricky, and has many complications to resolve
3196 * deadlock or inconsistant data situations. Tread lightly!!!
3197 * There are B_CACHE and B_DELWRI interactions that must be dealt with by
3198 * the caller. Calling this code willy nilly can result in the loss of
3201 * allocbuf() only adjusts B_CACHE for VMIO buffers. getblk() deals with
3202 * B_CACHE for the non-VMIO case.
3204 * This routine does not need to be called from a critical section but you
3205 * must own the buffer.
3210 allocbuf(struct buf *bp, int size)
3212 int newbsize, mbsize;
3215 if (BUF_REFCNT(bp) == 0)
3216 panic("allocbuf: buffer not busy");
3218 if (bp->b_kvasize < size)
3219 panic("allocbuf: buffer too small");
3221 if ((bp->b_flags & B_VMIO) == 0) {
3225 * Just get anonymous memory from the kernel. Don't
3226 * mess with B_CACHE.
3228 mbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1);
3229 if (bp->b_flags & B_MALLOC)
3232 newbsize = round_page(size);
3234 if (newbsize < bp->b_bufsize) {
3236 * Malloced buffers are not shrunk
3238 if (bp->b_flags & B_MALLOC) {
3240 bp->b_bcount = size;
3242 kfree(bp->b_data, M_BIOBUF);
3243 if (bp->b_bufsize) {
3244 atomic_subtract_int(&bufmallocspace, bp->b_bufsize);
3248 bp->b_data = bp->b_kvabase;
3250 bp->b_flags &= ~B_MALLOC;
3256 (vm_offset_t) bp->b_data + newbsize,
3257 (vm_offset_t) bp->b_data + bp->b_bufsize);
3258 } else if (newbsize > bp->b_bufsize) {
3260 * We only use malloced memory on the first allocation.
3261 * and revert to page-allocated memory when the buffer
3264 if ((bufmallocspace < maxbufmallocspace) &&
3265 (bp->b_bufsize == 0) &&
3266 (mbsize <= PAGE_SIZE/2)) {
3268 bp->b_data = kmalloc(mbsize, M_BIOBUF, M_WAITOK);
3269 bp->b_bufsize = mbsize;
3270 bp->b_bcount = size;
3271 bp->b_flags |= B_MALLOC;
3272 atomic_add_int(&bufmallocspace, mbsize);
3278 * If the buffer is growing on its other-than-first
3279 * allocation, then we revert to the page-allocation
3282 if (bp->b_flags & B_MALLOC) {
3283 origbuf = bp->b_data;
3284 origbufsize = bp->b_bufsize;
3285 bp->b_data = bp->b_kvabase;
3286 if (bp->b_bufsize) {
3287 atomic_subtract_int(&bufmallocspace,
3292 bp->b_flags &= ~B_MALLOC;
3293 newbsize = round_page(newbsize);
3297 (vm_offset_t) bp->b_data + bp->b_bufsize,
3298 (vm_offset_t) bp->b_data + newbsize);
3300 bcopy(origbuf, bp->b_data, origbufsize);
3301 kfree(origbuf, M_BIOBUF);
3308 newbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1);
3309 desiredpages = ((int)(bp->b_loffset & PAGE_MASK) +
3310 newbsize + PAGE_MASK) >> PAGE_SHIFT;
3311 KKASSERT(desiredpages <= XIO_INTERNAL_PAGES);
3313 if (bp->b_flags & B_MALLOC)
3314 panic("allocbuf: VMIO buffer can't be malloced");
3316 * Set B_CACHE initially if buffer is 0 length or will become
3319 if (size == 0 || bp->b_bufsize == 0)
3320 bp->b_flags |= B_CACHE;
3322 if (newbsize < bp->b_bufsize) {
3324 * DEV_BSIZE aligned new buffer size is less then the
3325 * DEV_BSIZE aligned existing buffer size. Figure out
3326 * if we have to remove any pages.
3328 if (desiredpages < bp->b_xio.xio_npages) {
3329 for (i = desiredpages; i < bp->b_xio.xio_npages; i++) {
3331 * the page is not freed here -- it
3332 * is the responsibility of
3333 * vnode_pager_setsize
3335 m = bp->b_xio.xio_pages[i];
3336 KASSERT(m != bogus_page,
3337 ("allocbuf: bogus page found"));
3338 while (vm_page_sleep_busy(m, TRUE, "biodep"))
3341 bp->b_xio.xio_pages[i] = NULL;
3342 vm_page_unwire(m, 0);
3344 pmap_qremove((vm_offset_t) trunc_page((vm_offset_t)bp->b_data) +
3345 (desiredpages << PAGE_SHIFT), (bp->b_xio.xio_npages - desiredpages));
3346 bp->b_xio.xio_npages = desiredpages;
3348 } else if (size > bp->b_bcount) {
3350 * We are growing the buffer, possibly in a
3351 * byte-granular fashion.
3359 * Step 1, bring in the VM pages from the object,
3360 * allocating them if necessary. We must clear
3361 * B_CACHE if these pages are not valid for the
3362 * range covered by the buffer.
3364 * critical section protection is required to protect
3365 * against interrupts unbusying and freeing pages
3366 * between our vm_page_lookup() and our
3367 * busycheck/wiring call.
3372 lwkt_gettoken(&vm_token);
3373 while (bp->b_xio.xio_npages < desiredpages) {
3377 pi = OFF_TO_IDX(bp->b_loffset) + bp->b_xio.xio_npages;
3378 if ((m = vm_page_lookup(obj, pi)) == NULL) {
3380 * note: must allocate system pages
3381 * since blocking here could intefere
3382 * with paging I/O, no matter which
3385 m = bio_page_alloc(obj, pi, desiredpages - bp->b_xio.xio_npages);
3388 vm_page_flag_clear(m, PG_ZERO);
3390 bp->b_flags &= ~B_CACHE;
3391 bp->b_xio.xio_pages[bp->b_xio.xio_npages] = m;
3392 ++bp->b_xio.xio_npages;
3398 * We found a page. If we have to sleep on it,
3399 * retry because it might have gotten freed out
3402 * We can only test PG_BUSY here. Blocking on
3403 * m->busy might lead to a deadlock:
3405 * vm_fault->getpages->cluster_read->allocbuf
3409 if (vm_page_sleep_busy(m, FALSE, "pgtblk"))
3411 vm_page_flag_clear(m, PG_ZERO);
3413 bp->b_xio.xio_pages[bp->b_xio.xio_npages] = m;
3414 ++bp->b_xio.xio_npages;
3415 if (bp->b_act_count < m->act_count)
3416 bp->b_act_count = m->act_count;
3418 lwkt_reltoken(&vm_token);
3421 * Step 2. We've loaded the pages into the buffer,
3422 * we have to figure out if we can still have B_CACHE
3423 * set. Note that B_CACHE is set according to the
3424 * byte-granular range ( bcount and size ), not the
3425 * aligned range ( newbsize ).
3427 * The VM test is against m->valid, which is DEV_BSIZE
3428 * aligned. Needless to say, the validity of the data
3429 * needs to also be DEV_BSIZE aligned. Note that this
3430 * fails with NFS if the server or some other client
3431 * extends the file's EOF. If our buffer is resized,
3432 * B_CACHE may remain set! XXX
3435 toff = bp->b_bcount;
3436 tinc = PAGE_SIZE - ((bp->b_loffset + toff) & PAGE_MASK);
3438 while ((bp->b_flags & B_CACHE) && toff < size) {
3441 if (tinc > (size - toff))
3444 pi = ((bp->b_loffset & PAGE_MASK) + toff) >>
3452 bp->b_xio.xio_pages[pi]
3459 * Step 3, fixup the KVM pmap. Remember that
3460 * bp->b_data is relative to bp->b_loffset, but
3461 * bp->b_loffset may be offset into the first page.
3464 bp->b_data = (caddr_t)
3465 trunc_page((vm_offset_t)bp->b_data);
3467 (vm_offset_t)bp->b_data,
3468 bp->b_xio.xio_pages,
3469 bp->b_xio.xio_npages
3471 bp->b_data = (caddr_t)((vm_offset_t)bp->b_data |
3472 (vm_offset_t)(bp->b_loffset & PAGE_MASK));
3476 /* adjust space use on already-dirty buffer */
3477 if (bp->b_flags & B_DELWRI) {
3478 spin_lock(&bufcspin);
3479 dirtybufspace += newbsize - bp->b_bufsize;
3480 if (bp->b_flags & B_HEAVY)
3481 dirtybufspacehw += newbsize - bp->b_bufsize;
3482 spin_unlock(&bufcspin);
3484 if (newbsize < bp->b_bufsize)
3486 bp->b_bufsize = newbsize; /* actual buffer allocation */
3487 bp->b_bcount = size; /* requested buffer size */
3494 * Wait for buffer I/O completion, returning error status. B_EINTR
3495 * is converted into an EINTR error but not cleared (since a chain
3496 * of biowait() calls may occur).
3498 * On return bpdone() will have been called but the buffer will remain
3499 * locked and will not have been brelse()'d.
3501 * NOTE! If a timeout is specified and ETIMEDOUT occurs the I/O is
3502 * likely still in progress on return.
3504 * NOTE! This operation is on a BIO, not a BUF.
3506 * NOTE! BIO_DONE is cleared by vn_strategy()
3511 _biowait(struct bio *bio, const char *wmesg, int to)
3513 struct buf *bp = bio->bio_buf;
3518 KKASSERT(bio == &bp->b_bio1);
3520 flags = bio->bio_flags;
3521 if (flags & BIO_DONE)
3523 tsleep_interlock(bio, 0);
3524 nflags = flags | BIO_WANT;
3525 tsleep_interlock(bio, 0);
3526 if (atomic_cmpset_int(&bio->bio_flags, flags, nflags)) {
3528 error = tsleep(bio, PINTERLOCKED, wmesg, to);
3529 else if (bp->b_cmd == BUF_CMD_READ)
3530 error = tsleep(bio, PINTERLOCKED, "biord", to);
3532 error = tsleep(bio, PINTERLOCKED, "biowr", to);
3534 kprintf("tsleep error biowait %d\n", error);
3543 KKASSERT(bp->b_cmd == BUF_CMD_DONE);
3544 bio->bio_flags &= ~(BIO_DONE | BIO_SYNC);
3545 if (bp->b_flags & B_EINTR)
3547 if (bp->b_flags & B_ERROR)
3548 return (bp->b_error ? bp->b_error : EIO);
3553 biowait(struct bio *bio, const char *wmesg)
3555 return(_biowait(bio, wmesg, 0));
3559 biowait_timeout(struct bio *bio, const char *wmesg, int to)
3561 return(_biowait(bio, wmesg, to));
3565 * This associates a tracking count with an I/O. vn_strategy() and
3566 * dev_dstrategy() do this automatically but there are a few cases
3567 * where a vnode or device layer is bypassed when a block translation
3568 * is cached. In such cases bio_start_transaction() may be called on
3569 * the bypassed layers so the system gets an I/O in progress indication
3570 * for those higher layers.
3573 bio_start_transaction(struct bio *bio, struct bio_track *track)
3575 bio->bio_track = track;
3576 if (dsched_is_clear_buf_priv(bio->bio_buf))
3577 dsched_new_buf(bio->bio_buf);
3578 bio_track_ref(track);
3582 * Initiate I/O on a vnode.
3584 * SWAPCACHE OPERATION:
3586 * Real buffer cache buffers have a non-NULL bp->b_vp. Unfortunately
3587 * devfs also uses b_vp for fake buffers so we also have to check
3588 * that B_PAGING is 0. In this case the passed 'vp' is probably the
3589 * underlying block device. The swap assignments are related to the
3590 * buffer cache buffer's b_vp, not the passed vp.
3592 * The passed vp == bp->b_vp only in the case where the strategy call
3593 * is made on the vp itself for its own buffers (a regular file or
3594 * block device vp). The filesystem usually then re-calls vn_strategy()
3595 * after translating the request to an underlying device.
3597 * Cluster buffers set B_CLUSTER and the passed vp is the vp of the
3598 * underlying buffer cache buffers.
3600 * We can only deal with page-aligned buffers at the moment, because
3601 * we can't tell what the real dirty state for pages straddling a buffer
3604 * In order to call swap_pager_strategy() we must provide the VM object
3605 * and base offset for the underlying buffer cache pages so it can find
3609 vn_strategy(struct vnode *vp, struct bio *bio)
3611 struct bio_track *track;
3612 struct buf *bp = bio->bio_buf;
3614 KKASSERT(bp->b_cmd != BUF_CMD_DONE);
3617 * Set when an I/O is issued on the bp. Cleared by consumers
3618 * (aka HAMMER), allowing the consumer to determine if I/O had
3619 * actually occurred.
3621 bp->b_flags |= B_IODEBUG;
3624 * Handle the swap cache intercept.
3626 if (vn_cache_strategy(vp, bio))
3630 * Otherwise do the operation through the filesystem
3632 if (bp->b_cmd == BUF_CMD_READ)
3633 track = &vp->v_track_read;
3635 track = &vp->v_track_write;
3636 KKASSERT((bio->bio_flags & BIO_DONE) == 0);
3637 bio->bio_track = track;
3638 if (dsched_is_clear_buf_priv(bio->bio_buf))
3639 dsched_new_buf(bio->bio_buf);
3640 bio_track_ref(track);
3641 vop_strategy(*vp->v_ops, vp, bio);
3644 static void vn_cache_strategy_callback(struct bio *bio);
3647 vn_cache_strategy(struct vnode *vp, struct bio *bio)
3649 struct buf *bp = bio->bio_buf;
3656 * Is this buffer cache buffer suitable for reading from
3659 if (vm_swapcache_read_enable == 0 ||
3660 bp->b_cmd != BUF_CMD_READ ||
3661 ((bp->b_flags & B_CLUSTER) == 0 &&
3662 (bp->b_vp == NULL || (bp->b_flags & B_PAGING))) ||
3663 ((int)bp->b_loffset & PAGE_MASK) != 0 ||
3664 (bp->b_bcount & PAGE_MASK) != 0) {
3669 * Figure out the original VM object (it will match the underlying
3670 * VM pages). Note that swap cached data uses page indices relative
3671 * to that object, not relative to bio->bio_offset.
3673 if (bp->b_flags & B_CLUSTER)
3674 object = vp->v_object;
3676 object = bp->b_vp->v_object;
3679 * In order to be able to use the swap cache all underlying VM
3680 * pages must be marked as such, and we can't have any bogus pages.
3682 for (i = 0; i < bp->b_xio.xio_npages; ++i) {
3683 m = bp->b_xio.xio_pages[i];
3684 if ((m->flags & PG_SWAPPED) == 0)
3686 if (m == bogus_page)
3691 * If we are good then issue the I/O using swap_pager_strategy().
3693 if (i == bp->b_xio.xio_npages) {
3694 m = bp->b_xio.xio_pages[0];
3695 nbio = push_bio(bio);
3696 nbio->bio_done = vn_cache_strategy_callback;
3697 nbio->bio_offset = ptoa(m->pindex);
3698 KKASSERT(m->object == object);
3699 swap_pager_strategy(object, nbio);
3706 * This is a bit of a hack but since the vn_cache_strategy() function can
3707 * override a VFS's strategy function we must make sure that the bio, which
3708 * is probably bio2, doesn't leak an unexpected offset value back to the
3709 * filesystem. The filesystem (e.g. UFS) might otherwise assume that the
3710 * bio went through its own file strategy function and the the bio2 offset
3711 * is a cached disk offset when, in fact, it isn't.
3714 vn_cache_strategy_callback(struct bio *bio)
3716 bio->bio_offset = NOOFFSET;
3717 biodone(pop_bio(bio));
3723 * Finish I/O on a buffer after all BIOs have been processed.
3724 * Called when the bio chain is exhausted or by biowait. If called
3725 * by biowait, elseit is typically 0.
3727 * bpdone is also responsible for setting B_CACHE in a B_VMIO bp.
3728 * In a non-VMIO bp, B_CACHE will be set on the next getblk()
3729 * assuming B_INVAL is clear.
3731 * For the VMIO case, we set B_CACHE if the op was a read and no
3732 * read error occured, or if the op was a write. B_CACHE is never
3733 * set if the buffer is invalid or otherwise uncacheable.
3735 * bpdone does not mess with B_INVAL, allowing the I/O routine or the
3736 * initiator to leave B_INVAL set to brelse the buffer out of existance
3737 * in the biodone routine.
3740 bpdone(struct buf *bp, int elseit)
3744 KASSERT(BUF_REFCNTNB(bp) > 0,
3745 ("biodone: bp %p not busy %d", bp, BUF_REFCNTNB(bp)));
3746 KASSERT(bp->b_cmd != BUF_CMD_DONE,
3747 ("biodone: bp %p already done!", bp));
3750 * No more BIOs are left. All completion functions have been dealt
3751 * with, now we clean up the buffer.
3754 bp->b_cmd = BUF_CMD_DONE;
3757 * Only reads and writes are processed past this point.
3759 if (cmd != BUF_CMD_READ && cmd != BUF_CMD_WRITE) {
3760 if (cmd == BUF_CMD_FREEBLKS)
3761 bp->b_flags |= B_NOCACHE;
3768 * Warning: softupdates may re-dirty the buffer, and HAMMER can do
3769 * a lot worse. XXX - move this above the clearing of b_cmd
3771 if (LIST_FIRST(&bp->b_dep) != NULL)
3772 buf_complete(bp); /* MPSAFE */
3775 * A failed write must re-dirty the buffer unless B_INVAL
3776 * was set. Only applicable to normal buffers (with VPs).
3777 * vinum buffers may not have a vp.
3779 if (cmd == BUF_CMD_WRITE &&
3780 (bp->b_flags & (B_ERROR | B_INVAL)) == B_ERROR) {
3781 bp->b_flags &= ~B_NOCACHE;
3786 if (bp->b_flags & B_VMIO) {
3792 struct vnode *vp = bp->b_vp;
3796 #if defined(VFS_BIO_DEBUG)
3797 if (vp->v_auxrefs == 0)
3798 panic("biodone: zero vnode hold count");
3799 if ((vp->v_flag & VOBJBUF) == 0)
3800 panic("biodone: vnode is not setup for merged cache");
3803 foff = bp->b_loffset;
3804 KASSERT(foff != NOOFFSET, ("biodone: no buffer offset"));
3805 KASSERT(obj != NULL, ("biodone: missing VM object"));
3807 #if defined(VFS_BIO_DEBUG)
3808 if (obj->paging_in_progress < bp->b_xio.xio_npages) {
3809 kprintf("biodone: paging in progress(%d) < bp->b_xio.xio_npages(%d)\n",
3810 obj->paging_in_progress, bp->b_xio.xio_npages);
3815 * Set B_CACHE if the op was a normal read and no error
3816 * occured. B_CACHE is set for writes in the b*write()
3819 iosize = bp->b_bcount - bp->b_resid;
3820 if (cmd == BUF_CMD_READ &&
3821 (bp->b_flags & (B_INVAL|B_NOCACHE|B_ERROR)) == 0) {
3822 bp->b_flags |= B_CACHE;
3825 lwkt_gettoken(&vm_token);
3826 for (i = 0; i < bp->b_xio.xio_npages; i++) {
3830 resid = ((foff + PAGE_SIZE) & ~(off_t)PAGE_MASK) - foff;
3835 * cleanup bogus pages, restoring the originals. Since
3836 * the originals should still be wired, we don't have
3837 * to worry about interrupt/freeing races destroying
3838 * the VM object association.
3840 m = bp->b_xio.xio_pages[i];
3841 if (m == bogus_page) {
3843 m = vm_page_lookup(obj, OFF_TO_IDX(foff));
3845 panic("biodone: page disappeared");
3846 bp->b_xio.xio_pages[i] = m;
3847 pmap_qenter(trunc_page((vm_offset_t)bp->b_data),
3848 bp->b_xio.xio_pages, bp->b_xio.xio_npages);
3850 #if defined(VFS_BIO_DEBUG)
3851 if (OFF_TO_IDX(foff) != m->pindex) {
3852 kprintf("biodone: foff(%lu)/m->pindex(%ld) "
3854 (unsigned long)foff, (long)m->pindex);
3859 * In the write case, the valid and clean bits are
3860 * already changed correctly (see bdwrite()), so we
3861 * only need to do this here in the read case.
3863 if (cmd == BUF_CMD_READ && !bogusflag && resid > 0) {
3864 vfs_clean_one_page(bp, i, m);
3866 vm_page_flag_clear(m, PG_ZERO);
3869 * when debugging new filesystems or buffer I/O
3870 * methods, this is the most common error that pops
3871 * up. if you see this, you have not set the page
3872 * busy flag correctly!!!
3875 kprintf("biodone: page busy < 0, "
3876 "pindex: %d, foff: 0x(%x,%x), "
3877 "resid: %d, index: %d\n",
3878 (int) m->pindex, (int)(foff >> 32),
3879 (int) foff & 0xffffffff, resid, i);
3880 if (!vn_isdisk(vp, NULL))
3881 kprintf(" iosize: %ld, loffset: %lld, "
3882 "flags: 0x%08x, npages: %d\n",
3883 bp->b_vp->v_mount->mnt_stat.f_iosize,
3884 (long long)bp->b_loffset,
3885 bp->b_flags, bp->b_xio.xio_npages);
3887 kprintf(" VDEV, loffset: %lld, flags: 0x%08x, npages: %d\n",
3888 (long long)bp->b_loffset,
3889 bp->b_flags, bp->b_xio.xio_npages);
3890 kprintf(" valid: 0x%x, dirty: 0x%x, wired: %d\n",
3891 m->valid, m->dirty, m->wire_count);
3892 panic("biodone: page busy < 0");
3894 vm_page_io_finish(m);
3895 vm_object_pip_subtract(obj, 1);
3896 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK;
3899 bp->b_flags &= ~B_HASBOGUS;
3901 vm_object_pip_wakeupn(obj, 0);
3902 lwkt_reltoken(&vm_token);
3906 * Finish up by releasing the buffer. There are no more synchronous
3907 * or asynchronous completions, those were handled by bio_done
3911 if (bp->b_flags & (B_NOCACHE|B_INVAL|B_ERROR|B_RELBUF))
3922 biodone(struct bio *bio)
3924 struct buf *bp = bio->bio_buf;
3926 runningbufwakeup(bp);
3929 * Run up the chain of BIO's. Leave b_cmd intact for the duration.
3932 biodone_t *done_func;
3933 struct bio_track *track;
3936 * BIO tracking. Most but not all BIOs are tracked.
3938 if ((track = bio->bio_track) != NULL) {
3939 bio_track_rel(track);
3940 bio->bio_track = NULL;
3944 * A bio_done function terminates the loop. The function
3945 * will be responsible for any further chaining and/or
3946 * buffer management.
3948 * WARNING! The done function can deallocate the buffer!
3950 if ((done_func = bio->bio_done) != NULL) {
3951 bio->bio_done = NULL;
3955 bio = bio->bio_prev;
3959 * If we've run out of bio's do normal [a]synchronous completion.
3965 * Synchronous biodone - this terminates a synchronous BIO.
3967 * bpdone() is called with elseit=FALSE, leaving the buffer completed
3968 * but still locked. The caller must brelse() the buffer after waiting
3972 biodone_sync(struct bio *bio)
3974 struct buf *bp = bio->bio_buf;
3978 KKASSERT(bio == &bp->b_bio1);
3982 flags = bio->bio_flags;
3983 nflags = (flags | BIO_DONE) & ~BIO_WANT;
3985 if (atomic_cmpset_int(&bio->bio_flags, flags, nflags)) {
3986 if (flags & BIO_WANT)
3996 * This routine is called in lieu of iodone in the case of
3997 * incomplete I/O. This keeps the busy status for pages
4001 vfs_unbusy_pages(struct buf *bp)
4005 runningbufwakeup(bp);
4007 lwkt_gettoken(&vm_token);
4008 if (bp->b_flags & B_VMIO) {
4009 struct vnode *vp = bp->b_vp;
4014 for (i = 0; i < bp->b_xio.xio_npages; i++) {
4015 vm_page_t m = bp->b_xio.xio_pages[i];
4018 * When restoring bogus changes the original pages
4019 * should still be wired, so we are in no danger of
4020 * losing the object association and do not need
4021 * critical section protection particularly.
4023 if (m == bogus_page) {
4024 m = vm_page_lookup(obj, OFF_TO_IDX(bp->b_loffset) + i);
4026 panic("vfs_unbusy_pages: page missing");
4028 bp->b_xio.xio_pages[i] = m;
4029 pmap_qenter(trunc_page((vm_offset_t)bp->b_data),
4030 bp->b_xio.xio_pages, bp->b_xio.xio_npages);
4032 vm_object_pip_subtract(obj, 1);
4033 vm_page_flag_clear(m, PG_ZERO);
4034 vm_page_io_finish(m);
4036 bp->b_flags &= ~B_HASBOGUS;
4037 vm_object_pip_wakeupn(obj, 0);
4039 lwkt_reltoken(&vm_token);
4045 * This routine is called before a device strategy routine.
4046 * It is used to tell the VM system that paging I/O is in
4047 * progress, and treat the pages associated with the buffer
4048 * almost as being PG_BUSY. Also the object 'paging_in_progress'
4049 * flag is handled to make sure that the object doesn't become
4052 * Since I/O has not been initiated yet, certain buffer flags
4053 * such as B_ERROR or B_INVAL may be in an inconsistant state
4054 * and should be ignored.
4059 vfs_busy_pages(struct vnode *vp, struct buf *bp)
4062 struct lwp *lp = curthread->td_lwp;
4065 * The buffer's I/O command must already be set. If reading,
4066 * B_CACHE must be 0 (double check against callers only doing
4067 * I/O when B_CACHE is 0).
4069 KKASSERT(bp->b_cmd != BUF_CMD_DONE);
4070 KKASSERT(bp->b_cmd == BUF_CMD_WRITE || (bp->b_flags & B_CACHE) == 0);
4072 if (bp->b_flags & B_VMIO) {
4075 lwkt_gettoken(&vm_token);
4078 KASSERT(bp->b_loffset != NOOFFSET,
4079 ("vfs_busy_pages: no buffer offset"));
4082 * Loop until none of the pages are busy.
4085 for (i = 0; i < bp->b_xio.xio_npages; i++) {
4086 vm_page_t m = bp->b_xio.xio_pages[i];
4088 if (vm_page_sleep_busy(m, FALSE, "vbpage"))
4093 * Setup for I/O, soft-busy the page right now because
4094 * the next loop may block.
4096 for (i = 0; i < bp->b_xio.xio_npages; i++) {
4097 vm_page_t m = bp->b_xio.xio_pages[i];
4099 vm_page_flag_clear(m, PG_ZERO);
4100 if ((bp->b_flags & B_CLUSTER) == 0) {
4101 vm_object_pip_add(obj, 1);
4102 vm_page_io_start(m);
4107 * Adjust protections for I/O and do bogus-page mapping.
4108 * Assume that vm_page_protect() can block (it can block
4109 * if VM_PROT_NONE, don't take any chances regardless).
4111 * In particular note that for writes we must incorporate
4112 * page dirtyness from the VM system into the buffer's
4115 * For reads we theoretically must incorporate page dirtyness
4116 * from the VM system to determine if the page needs bogus
4117 * replacement, but we shortcut the test by simply checking
4118 * that all m->valid bits are set, indicating that the page
4119 * is fully valid and does not need to be re-read. For any
4120 * VM system dirtyness the page will also be fully valid
4121 * since it was mapped at one point.
4124 for (i = 0; i < bp->b_xio.xio_npages; i++) {
4125 vm_page_t m = bp->b_xio.xio_pages[i];
4127 vm_page_flag_clear(m, PG_ZERO); /* XXX */
4128 if (bp->b_cmd == BUF_CMD_WRITE) {
4130 * When readying a vnode-backed buffer for
4131 * a write we must zero-fill any invalid
4132 * portions of the backing VM pages, mark
4133 * it valid and clear related dirty bits.
4135 * vfs_clean_one_page() incorporates any
4136 * VM dirtyness and updates the b_dirtyoff
4137 * range (after we've made the page RO).
4139 * It is also expected that the pmap modified
4140 * bit has already been cleared by the
4141 * vm_page_protect(). We may not be able
4142 * to clear all dirty bits for a page if it
4143 * was also memory mapped (NFS).
4145 * Finally be sure to unassign any swap-cache
4146 * backing store as it is now stale.
4148 vm_page_protect(m, VM_PROT_READ);
4149 vfs_clean_one_page(bp, i, m);
4150 swap_pager_unswapped(m);
4151 } else if (m->valid == VM_PAGE_BITS_ALL) {
4153 * When readying a vnode-backed buffer for
4154 * read we must replace any dirty pages with
4155 * a bogus page so dirty data is not destroyed
4156 * when filling gaps.
4158 * To avoid testing whether the page is
4159 * dirty we instead test that the page was
4160 * at some point mapped (m->valid fully
4161 * valid) with the understanding that
4162 * this also covers the dirty case.
4164 bp->b_xio.xio_pages[i] = bogus_page;
4165 bp->b_flags |= B_HASBOGUS;
4167 } else if (m->valid & m->dirty) {
4169 * This case should not occur as partial
4170 * dirtyment can only happen if the buffer
4171 * is B_CACHE, and this code is not entered
4172 * if the buffer is B_CACHE.
4174 kprintf("Warning: vfs_busy_pages - page not "
4175 "fully valid! loff=%jx bpf=%08x "
4176 "idx=%d val=%02x dir=%02x\n",
4177 (intmax_t)bp->b_loffset, bp->b_flags,
4178 i, m->valid, m->dirty);
4179 vm_page_protect(m, VM_PROT_NONE);
4182 * The page is not valid and can be made
4185 vm_page_protect(m, VM_PROT_NONE);
4189 pmap_qenter(trunc_page((vm_offset_t)bp->b_data),
4190 bp->b_xio.xio_pages, bp->b_xio.xio_npages);
4192 lwkt_reltoken(&vm_token);
4196 * This is the easiest place to put the process accounting for the I/O
4200 if (bp->b_cmd == BUF_CMD_READ)
4201 lp->lwp_ru.ru_inblock++;
4203 lp->lwp_ru.ru_oublock++;
4208 * Tell the VM system that the pages associated with this buffer
4209 * are clean. This is used for delayed writes where the data is
4210 * going to go to disk eventually without additional VM intevention.
4212 * NOTE: While we only really need to clean through to b_bcount, we
4213 * just go ahead and clean through to b_bufsize.
4216 vfs_clean_pages(struct buf *bp)
4221 if ((bp->b_flags & B_VMIO) == 0)
4224 KASSERT(bp->b_loffset != NOOFFSET,
4225 ("vfs_clean_pages: no buffer offset"));
4228 * vm_token must be held for vfs_clean_one_page() calls.
4230 lwkt_gettoken(&vm_token);
4231 for (i = 0; i < bp->b_xio.xio_npages; i++) {
4232 m = bp->b_xio.xio_pages[i];
4233 vfs_clean_one_page(bp, i, m);
4235 lwkt_reltoken(&vm_token);
4239 * vfs_clean_one_page:
4241 * Set the valid bits and clear the dirty bits in a page within a
4242 * buffer. The range is restricted to the buffer's size and the
4243 * buffer's logical offset might index into the first page.
4245 * The caller has busied or soft-busied the page and it is not mapped,
4246 * test and incorporate the dirty bits into b_dirtyoff/end before
4247 * clearing them. Note that we need to clear the pmap modified bits
4248 * after determining the the page was dirty, vm_page_set_validclean()
4249 * does not do it for us.
4251 * This routine is typically called after a read completes (dirty should
4252 * be zero in that case as we are not called on bogus-replace pages),
4253 * or before a write is initiated.
4255 * NOTE: vm_token must be held by the caller, and vm_page_set_validclean()
4256 * currently assumes the vm_token is held.
4259 vfs_clean_one_page(struct buf *bp, int pageno, vm_page_t m)
4267 * Calculate offset range within the page but relative to buffer's
4268 * loffset. loffset might be offset into the first page.
4270 xoff = (int)bp->b_loffset & PAGE_MASK; /* loffset offset into pg 0 */
4271 bcount = bp->b_bcount + xoff; /* offset adjusted */
4277 soff = (pageno << PAGE_SHIFT);
4278 eoff = soff + PAGE_SIZE;
4286 * Test dirty bits and adjust b_dirtyoff/end.
4288 * If dirty pages are incorporated into the bp any prior
4289 * B_NEEDCOMMIT state (NFS) must be cleared because the
4290 * caller has not taken into account the new dirty data.
4292 * If the page was memory mapped the dirty bits might go beyond the
4293 * end of the buffer, but we can't really make the assumption that
4294 * a file EOF straddles the buffer (even though this is the case for
4295 * NFS if B_NEEDCOMMIT is also set). So for the purposes of clearing
4296 * B_NEEDCOMMIT we only test the dirty bits covered by the buffer.
4297 * This also saves some console spam.
4299 * When clearing B_NEEDCOMMIT we must also clear B_CLUSTEROK,
4300 * NFS can handle huge commits but not huge writes.
4302 vm_page_test_dirty(m);
4304 if ((bp->b_flags & B_NEEDCOMMIT) &&
4305 (m->dirty & vm_page_bits(soff & PAGE_MASK, eoff - soff))) {
4307 kprintf("Warning: vfs_clean_one_page: bp %p "
4308 "loff=%jx,%d flgs=%08x clr B_NEEDCOMMIT"
4309 " cmd %d vd %02x/%02x x/s/e %d %d %d "
4311 bp, (intmax_t)bp->b_loffset, bp->b_bcount,
4312 bp->b_flags, bp->b_cmd,
4313 m->valid, m->dirty, xoff, soff, eoff,
4314 bp->b_dirtyoff, bp->b_dirtyend);
4315 bp->b_flags &= ~(B_NEEDCOMMIT | B_CLUSTEROK);
4317 print_backtrace(-1);
4320 * Only clear the pmap modified bits if ALL the dirty bits
4321 * are set, otherwise the system might mis-clear portions
4324 if (m->dirty == VM_PAGE_BITS_ALL &&
4325 (bp->b_flags & B_NEEDCOMMIT) == 0) {
4326 pmap_clear_modify(m);
4328 if (bp->b_dirtyoff > soff - xoff)
4329 bp->b_dirtyoff = soff - xoff;
4330 if (bp->b_dirtyend < eoff - xoff)
4331 bp->b_dirtyend = eoff - xoff;
4335 * Set related valid bits, clear related dirty bits.
4336 * Does not mess with the pmap modified bit.
4338 * WARNING! We cannot just clear all of m->dirty here as the
4339 * buffer cache buffers may use a DEV_BSIZE'd aligned
4340 * block size, or have an odd size (e.g. NFS at file EOF).
4341 * The putpages code can clear m->dirty to 0.
4343 * If a VOP_WRITE generates a buffer cache buffer which
4344 * covers the same space as mapped writable pages the
4345 * buffer flush might not be able to clear all the dirty
4346 * bits and still require a putpages from the VM system
4349 * WARNING! vm_page_set_validclean() currently assumes vm_token
4350 * is held. The page might not be busied (bdwrite() case).
4352 vm_page_set_validclean(m, soff & PAGE_MASK, eoff - soff);
4356 * Similar to vfs_clean_one_page() but sets the bits to valid and dirty.
4357 * The page data is assumed to be valid (there is no zeroing here).
4360 vfs_dirty_one_page(struct buf *bp, int pageno, vm_page_t m)
4368 * Calculate offset range within the page but relative to buffer's
4369 * loffset. loffset might be offset into the first page.
4371 xoff = (int)bp->b_loffset & PAGE_MASK; /* loffset offset into pg 0 */
4372 bcount = bp->b_bcount + xoff; /* offset adjusted */
4378 soff = (pageno << PAGE_SHIFT);
4379 eoff = soff + PAGE_SIZE;
4385 vm_page_set_validdirty(m, soff & PAGE_MASK, eoff - soff);
4391 * Clear a buffer. This routine essentially fakes an I/O, so we need
4392 * to clear B_ERROR and B_INVAL.
4394 * Note that while we only theoretically need to clear through b_bcount,
4395 * we go ahead and clear through b_bufsize.
4399 vfs_bio_clrbuf(struct buf *bp)
4403 if ((bp->b_flags & (B_VMIO | B_MALLOC)) == B_VMIO) {
4404 bp->b_flags &= ~(B_INVAL | B_EINTR | B_ERROR);
4405 if ((bp->b_xio.xio_npages == 1) && (bp->b_bufsize < PAGE_SIZE) &&
4406 (bp->b_loffset & PAGE_MASK) == 0) {
4407 mask = (1 << (bp->b_bufsize / DEV_BSIZE)) - 1;
4408 if ((bp->b_xio.xio_pages[0]->valid & mask) == mask) {
4412 if (((bp->b_xio.xio_pages[0]->flags & PG_ZERO) == 0) &&
4413 ((bp->b_xio.xio_pages[0]->valid & mask) == 0)) {
4414 bzero(bp->b_data, bp->b_bufsize);
4415 bp->b_xio.xio_pages[0]->valid |= mask;
4421 for(i=0;i<bp->b_xio.xio_npages;i++,sa=ea) {
4422 int j = ((vm_offset_t)sa & PAGE_MASK) / DEV_BSIZE;
4423 ea = (caddr_t)trunc_page((vm_offset_t)sa + PAGE_SIZE);
4424 ea = (caddr_t)(vm_offset_t)ulmin(
4425 (u_long)(vm_offset_t)ea,
4426 (u_long)(vm_offset_t)bp->b_data + bp->b_bufsize);
4427 mask = ((1 << ((ea - sa) / DEV_BSIZE)) - 1) << j;
4428 if ((bp->b_xio.xio_pages[i]->valid & mask) == mask)
4430 if ((bp->b_xio.xio_pages[i]->valid & mask) == 0) {
4431 if ((bp->b_xio.xio_pages[i]->flags & PG_ZERO) == 0) {
4435 for (; sa < ea; sa += DEV_BSIZE, j++) {
4436 if (((bp->b_xio.xio_pages[i]->flags & PG_ZERO) == 0) &&
4437 (bp->b_xio.xio_pages[i]->valid & (1<<j)) == 0)
4438 bzero(sa, DEV_BSIZE);
4441 bp->b_xio.xio_pages[i]->valid |= mask;
4442 vm_page_flag_clear(bp->b_xio.xio_pages[i], PG_ZERO);
4451 * vm_hold_load_pages:
4453 * Load pages into the buffer's address space. The pages are
4454 * allocated from the kernel object in order to reduce interference
4455 * with the any VM paging I/O activity. The range of loaded
4456 * pages will be wired.
4458 * If a page cannot be allocated, the 'pagedaemon' is woken up to
4459 * retrieve the full range (to - from) of pages.
4464 vm_hold_load_pages(struct buf *bp, vm_offset_t from, vm_offset_t to)
4470 to = round_page(to);
4471 from = round_page(from);
4472 index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT;
4477 * Note: must allocate system pages since blocking here
4478 * could intefere with paging I/O, no matter which
4481 p = bio_page_alloc(&kernel_object, pg >> PAGE_SHIFT,
4482 (vm_pindex_t)((to - pg) >> PAGE_SHIFT));
4485 p->valid = VM_PAGE_BITS_ALL;
4486 vm_page_flag_clear(p, PG_ZERO);
4487 pmap_kenter(pg, VM_PAGE_TO_PHYS(p));
4488 bp->b_xio.xio_pages[index] = p;
4495 bp->b_xio.xio_npages = index;
4499 * Allocate pages for a buffer cache buffer.
4501 * Under extremely severe memory conditions even allocating out of the
4502 * system reserve can fail. If this occurs we must allocate out of the
4503 * interrupt reserve to avoid a deadlock with the pageout daemon.
4505 * The pageout daemon can run (putpages -> VOP_WRITE -> getblk -> allocbuf).
4506 * If the buffer cache's vm_page_alloc() fails a vm_wait() can deadlock
4507 * against the pageout daemon if pages are not freed from other sources.
4513 bio_page_alloc(vm_object_t obj, vm_pindex_t pg, int deficit)
4518 * Try a normal allocation, allow use of system reserve.
4520 lwkt_gettoken(&vm_token);
4521 p = vm_page_alloc(obj, pg, VM_ALLOC_NORMAL | VM_ALLOC_SYSTEM);
4523 lwkt_reltoken(&vm_token);
4528 * The normal allocation failed and we clearly have a page
4529 * deficit. Try to reclaim some clean VM pages directly
4530 * from the buffer cache.
4532 vm_pageout_deficit += deficit;
4536 * We may have blocked, the caller will know what to do if the
4539 if (vm_page_lookup(obj, pg)) {
4540 lwkt_reltoken(&vm_token);
4545 * Allocate and allow use of the interrupt reserve.
4547 * If after all that we still can't allocate a VM page we are
4548 * in real trouble, but we slog on anyway hoping that the system
4551 p = vm_page_alloc(obj, pg, VM_ALLOC_NORMAL | VM_ALLOC_SYSTEM |
4552 VM_ALLOC_INTERRUPT);
4554 if (vm_page_count_severe()) {
4556 vm_wait(hz / 20 + 1);
4559 kprintf("bio_page_alloc: Memory exhausted during bufcache "
4560 "page allocation\n");
4564 lwkt_reltoken(&vm_token);
4569 * vm_hold_free_pages:
4571 * Return pages associated with the buffer back to the VM system.
4573 * The range of pages underlying the buffer's address space will
4574 * be unmapped and un-wired.
4579 vm_hold_free_pages(struct buf *bp, vm_offset_t from, vm_offset_t to)
4583 int index, newnpages;
4585 from = round_page(from);
4586 to = round_page(to);
4587 index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT;
4590 lwkt_gettoken(&vm_token);
4591 for (pg = from; pg < to; pg += PAGE_SIZE, index++) {
4592 p = bp->b_xio.xio_pages[index];
4593 if (p && (index < bp->b_xio.xio_npages)) {
4595 kprintf("vm_hold_free_pages: doffset: %lld, "
4597 (long long)bp->b_bio2.bio_offset,
4598 (long long)bp->b_loffset);
4600 bp->b_xio.xio_pages[index] = NULL;
4603 vm_page_unwire(p, 0);
4607 bp->b_xio.xio_npages = newnpages;
4608 lwkt_reltoken(&vm_token);
4614 * Map a user buffer into KVM via a pbuf. On return the buffer's
4615 * b_data, b_bufsize, and b_bcount will be set, and its XIO page array
4619 vmapbuf(struct buf *bp, caddr_t udata, int bytes)
4630 * bp had better have a command and it better be a pbuf.
4632 KKASSERT(bp->b_cmd != BUF_CMD_DONE);
4633 KKASSERT(bp->b_flags & B_PAGING);
4634 KKASSERT(bp->b_kvabase);
4640 * Map the user data into KVM. Mappings have to be page-aligned.
4642 addr = (caddr_t)trunc_page((vm_offset_t)udata);
4645 vmprot = VM_PROT_READ;
4646 if (bp->b_cmd == BUF_CMD_READ)
4647 vmprot |= VM_PROT_WRITE;
4649 while (addr < udata + bytes) {
4651 * Do the vm_fault if needed; do the copy-on-write thing
4652 * when reading stuff off device into memory.
4654 * vm_fault_page*() returns a held VM page.
4656 va = (addr >= udata) ? (vm_offset_t)addr : (vm_offset_t)udata;
4657 va = trunc_page(va);
4659 m = vm_fault_page_quick(va, vmprot, &error);
4661 for (i = 0; i < pidx; ++i) {
4662 vm_page_unhold(bp->b_xio.xio_pages[i]);
4663 bp->b_xio.xio_pages[i] = NULL;
4667 bp->b_xio.xio_pages[pidx] = m;
4673 * Map the page array and set the buffer fields to point to
4674 * the mapped data buffer.
4676 if (pidx > btoc(MAXPHYS))
4677 panic("vmapbuf: mapped more than MAXPHYS");
4678 pmap_qenter((vm_offset_t)bp->b_kvabase, bp->b_xio.xio_pages, pidx);
4680 bp->b_xio.xio_npages = pidx;
4681 bp->b_data = bp->b_kvabase + ((int)(intptr_t)udata & PAGE_MASK);
4682 bp->b_bcount = bytes;
4683 bp->b_bufsize = bytes;
4690 * Free the io map PTEs associated with this IO operation.
4691 * We also invalidate the TLB entries and restore the original b_addr.
4694 vunmapbuf(struct buf *bp)
4699 KKASSERT(bp->b_flags & B_PAGING);
4701 npages = bp->b_xio.xio_npages;
4702 pmap_qremove(trunc_page((vm_offset_t)bp->b_data), npages);
4703 for (pidx = 0; pidx < npages; ++pidx) {
4704 vm_page_unhold(bp->b_xio.xio_pages[pidx]);
4705 bp->b_xio.xio_pages[pidx] = NULL;
4707 bp->b_xio.xio_npages = 0;
4708 bp->b_data = bp->b_kvabase;
4712 * Scan all buffers in the system and issue the callback.
4715 scan_all_buffers(int (*callback)(struct buf *, void *), void *info)
4721 for (n = 0; n < nbuf; ++n) {
4722 if ((error = callback(&buf[n], info)) < 0) {
4732 * nestiobuf_iodone: biodone callback for nested buffers and propagate
4733 * completion to the master buffer.
4736 nestiobuf_iodone(struct bio *bio)
4739 struct buf *mbp, *bp;
4740 struct devstat *stats;
4745 mbio = bio->bio_caller_info1.ptr;
4746 stats = bio->bio_caller_info2.ptr;
4747 mbp = mbio->bio_buf;
4749 KKASSERT(bp->b_bcount <= bp->b_bufsize);
4750 KKASSERT(mbp != bp);
4752 error = bp->b_error;
4753 if (bp->b_error == 0 &&
4754 (bp->b_bcount < bp->b_bufsize || bp->b_resid > 0)) {
4756 * Not all got transfered, raise an error. We have no way to
4757 * propagate these conditions to mbp.
4762 donebytes = bp->b_bufsize;
4766 nestiobuf_done(mbio, donebytes, error, stats);
4770 nestiobuf_done(struct bio *mbio, int donebytes, int error, struct devstat *stats)
4774 mbp = mbio->bio_buf;
4776 KKASSERT((int)(intptr_t)mbio->bio_driver_info > 0);
4779 * If an error occured, propagate it to the master buffer.
4781 * Several biodone()s may wind up running concurrently so
4782 * use an atomic op to adjust b_flags.
4785 mbp->b_error = error;
4786 atomic_set_int(&mbp->b_flags, B_ERROR);
4790 * Decrement the operations in progress counter and terminate the
4791 * I/O if this was the last bit.
4793 if (atomic_fetchadd_int((int *)&mbio->bio_driver_info, -1) == 1) {
4796 devstat_end_transaction_buf(stats, mbp);
4802 * Initialize a nestiobuf for use. Set an initial count of 1 to prevent
4803 * the mbio from being biodone()'d while we are still adding sub-bios to
4807 nestiobuf_init(struct bio *bio)
4809 bio->bio_driver_info = (void *)1;
4813 * The BIOs added to the nestedio have already been started, remove the
4814 * count that placeheld our mbio and biodone() it if the count would
4818 nestiobuf_start(struct bio *mbio)
4820 struct buf *mbp = mbio->bio_buf;
4823 * Decrement the operations in progress counter and terminate the
4824 * I/O if this was the last bit.
4826 if (atomic_fetchadd_int((int *)&mbio->bio_driver_info, -1) == 1) {
4827 if (mbp->b_flags & B_ERROR)
4828 mbp->b_resid = mbp->b_bcount;
4836 * Set an intermediate error prior to calling nestiobuf_start()
4839 nestiobuf_error(struct bio *mbio, int error)
4841 struct buf *mbp = mbio->bio_buf;
4844 mbp->b_error = error;
4845 atomic_set_int(&mbp->b_flags, B_ERROR);
4850 * nestiobuf_add: setup a "nested" buffer.
4852 * => 'mbp' is a "master" buffer which is being divided into sub pieces.
4853 * => 'bp' should be a buffer allocated by getiobuf.
4854 * => 'offset' is a byte offset in the master buffer.
4855 * => 'size' is a size in bytes of this nested buffer.
4858 nestiobuf_add(struct bio *mbio, struct buf *bp, int offset, size_t size, struct devstat *stats)
4860 struct buf *mbp = mbio->bio_buf;
4861 struct vnode *vp = mbp->b_vp;
4863 KKASSERT(mbp->b_bcount >= offset + size);
4865 atomic_add_int((int *)&mbio->bio_driver_info, 1);
4867 /* kernel needs to own the lock for it to be released in biodone */
4870 bp->b_cmd = mbp->b_cmd;
4871 bp->b_bio1.bio_done = nestiobuf_iodone;
4872 bp->b_data = (char *)mbp->b_data + offset;
4873 bp->b_resid = bp->b_bcount = size;
4874 bp->b_bufsize = bp->b_bcount;
4876 bp->b_bio1.bio_track = NULL;
4877 bp->b_bio1.bio_caller_info1.ptr = mbio;
4878 bp->b_bio1.bio_caller_info2.ptr = stats;
4882 * print out statistics from the current status of the buffer pool
4883 * this can be toggeled by the system control option debug.syncprt
4892 int counts[(MAXBSIZE / PAGE_SIZE) + 1];
4893 static char *bname[3] = { "LOCKED", "LRU", "AGE" };
4895 for (dp = bufqueues, i = 0; dp < &bufqueues[3]; dp++, i++) {
4897 for (j = 0; j <= MAXBSIZE/PAGE_SIZE; j++)
4900 spin_lock(&bufqspin);
4901 TAILQ_FOREACH(bp, dp, b_freelist) {
4902 counts[bp->b_bufsize/PAGE_SIZE]++;
4905 spin_unlock(&bufqspin);
4907 kprintf("%s: total-%d", bname[i], count);
4908 for (j = 0; j <= MAXBSIZE/PAGE_SIZE; j++)
4910 kprintf(", %d-%d", j * PAGE_SIZE, counts[j]);
4918 DB_SHOW_COMMAND(buffer, db_show_buffer)
4921 struct buf *bp = (struct buf *)addr;
4924 db_printf("usage: show buffer <addr>\n");
4928 db_printf("b_flags = 0x%b\n", (u_int)bp->b_flags, PRINT_BUF_FLAGS);
4929 db_printf("b_cmd = %d\n", bp->b_cmd);
4930 db_printf("b_error = %d, b_bufsize = %d, b_bcount = %d, "
4931 "b_resid = %d\n, b_data = %p, "
4932 "bio_offset(disk) = %lld, bio_offset(phys) = %lld\n",
4933 bp->b_error, bp->b_bufsize, bp->b_bcount, bp->b_resid,
4935 (long long)bp->b_bio2.bio_offset,
4936 (long long)(bp->b_bio2.bio_next ?
4937 bp->b_bio2.bio_next->bio_offset : (off_t)-1));
4938 if (bp->b_xio.xio_npages) {
4940 db_printf("b_xio.xio_npages = %d, pages(OBJ, IDX, PA): ",
4941 bp->b_xio.xio_npages);
4942 for (i = 0; i < bp->b_xio.xio_npages; i++) {
4944 m = bp->b_xio.xio_pages[i];
4945 db_printf("(%p, 0x%lx, 0x%lx)", (void *)m->object,
4946 (u_long)m->pindex, (u_long)VM_PAGE_TO_PHYS(m));
4947 if ((i + 1) < bp->b_xio.xio_npages)