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 $
18 * this file contains a new buffer I/O scheme implementing a coherent
19 * VM object and buffer cache scheme. Pains have been taken to make
20 * sure that the performance degradation associated with schemes such
21 * as this is not realized.
23 * Author: John S. Dyson
24 * Significant help during the development and debugging phases
25 * had been provided by David Greenman, also of the FreeBSD core team.
27 * see man buf(9) for more info. Note that man buf(9) doesn't reflect
28 * the actual buf/bio implementation in DragonFly.
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>
50 #include <vm/vm_param.h>
51 #include <vm/vm_kern.h>
52 #include <vm/vm_pageout.h>
53 #include <vm/vm_page.h>
54 #include <vm/vm_object.h>
55 #include <vm/vm_extern.h>
56 #include <vm/vm_map.h>
57 #include <vm/vm_pager.h>
58 #include <vm/swap_pager.h>
61 #include <sys/thread2.h>
62 #include <sys/spinlock2.h>
63 #include <sys/mplock2.h>
64 #include <vm/vm_page2.h>
75 BQUEUE_NONE
, /* not on any queue */
76 BQUEUE_LOCKED
, /* locked buffers */
77 BQUEUE_CLEAN
, /* non-B_DELWRI buffers */
78 BQUEUE_DIRTY
, /* B_DELWRI buffers */
79 BQUEUE_DIRTY_HW
, /* B_DELWRI buffers - heavy weight */
80 BQUEUE_EMPTYKVA
, /* empty buffer headers with KVA assignment */
81 BQUEUE_EMPTY
, /* empty buffer headers */
83 BUFFER_QUEUES
/* number of buffer queues */
86 typedef enum bufq_type bufq_type_t
;
88 #define BD_WAKE_SIZE 16384
89 #define BD_WAKE_MASK (BD_WAKE_SIZE - 1)
91 TAILQ_HEAD(bqueues
, buf
);
95 struct bqueues bufqueues
[BUFFER_QUEUES
];
98 struct bufpcpu bufpcpu
[MAXCPU
];
100 static MALLOC_DEFINE(M_BIOBUF
, "BIO buffer", "BIO buffer");
102 struct buf
*buf
; /* buffer header pool */
104 static void vfs_clean_pages(struct buf
*bp
);
105 static void vfs_clean_one_page(struct buf
*bp
, int pageno
, vm_page_t m
);
107 static void vfs_dirty_one_page(struct buf
*bp
, int pageno
, vm_page_t m
);
109 static void vfs_vmio_release(struct buf
*bp
);
110 static int flushbufqueues(struct buf
*marker
, bufq_type_t q
);
111 static vm_page_t
bio_page_alloc(struct buf
*bp
, vm_object_t obj
,
112 vm_pindex_t pg
, int deficit
);
114 static void bd_signal(long totalspace
);
115 static void buf_daemon(void);
116 static void buf_daemon_hw(void);
119 * bogus page -- for I/O to/from partially complete buffers
120 * this is a temporary solution to the problem, but it is not
121 * really that bad. it would be better to split the buffer
122 * for input in the case of buffers partially already in memory,
123 * but the code is intricate enough already.
125 vm_page_t bogus_page
;
128 * These are all static, but make the ones we export globals so we do
129 * not need to use compiler magic.
131 long bufspace
; /* locked by buffer_map */
133 static long bufmallocspace
; /* atomic ops */
134 long maxbufmallocspace
, lobufspace
, hibufspace
;
135 static long bufreusecnt
, bufdefragcnt
, buffreekvacnt
;
136 static long lorunningspace
;
137 static long hirunningspace
;
138 static long dirtykvaspace
; /* atomic */
139 long dirtybufspace
; /* atomic (global for systat) */
140 static long dirtybufcount
; /* atomic */
141 static long dirtybufspacehw
; /* atomic */
142 static long dirtybufcounthw
; /* atomic */
143 static long runningbufspace
; /* atomic */
144 static long runningbufcount
; /* atomic */
145 long lodirtybufspace
;
146 long hidirtybufspace
;
147 static int getnewbufcalls
;
148 static int getnewbufrestarts
;
149 static int recoverbufcalls
;
150 static int needsbuffer
; /* atomic */
151 static int runningbufreq
; /* atomic */
152 static int bd_request
; /* atomic */
153 static int bd_request_hw
; /* atomic */
154 static u_int bd_wake_ary
[BD_WAKE_SIZE
];
155 static u_int bd_wake_index
;
156 static u_int vm_cycle_point
= 40; /* 23-36 will migrate more act->inact */
157 static int debug_commit
;
158 static int debug_bufbio
;
160 static struct thread
*bufdaemon_td
;
161 static struct thread
*bufdaemonhw_td
;
162 static u_int lowmempgallocs
;
163 static u_int lowmempgfails
;
164 static u_int flushperqueue
= 1024;
167 * Sysctls for operational control of the buffer cache.
169 SYSCTL_UINT(_vfs
, OID_AUTO
, flushperqueue
, CTLFLAG_RW
, &flushperqueue
, 0,
170 "Number of buffers to flush from each per-cpu queue");
171 SYSCTL_LONG(_vfs
, OID_AUTO
, lodirtybufspace
, CTLFLAG_RW
, &lodirtybufspace
, 0,
172 "Number of dirty buffers to flush before bufdaemon becomes inactive");
173 SYSCTL_LONG(_vfs
, OID_AUTO
, hidirtybufspace
, CTLFLAG_RW
, &hidirtybufspace
, 0,
174 "High watermark used to trigger explicit flushing of dirty buffers");
175 SYSCTL_LONG(_vfs
, OID_AUTO
, lorunningspace
, CTLFLAG_RW
, &lorunningspace
, 0,
176 "Minimum amount of buffer space required for active I/O");
177 SYSCTL_LONG(_vfs
, OID_AUTO
, hirunningspace
, CTLFLAG_RW
, &hirunningspace
, 0,
178 "Maximum amount of buffer space to usable for active I/O");
179 SYSCTL_UINT(_vfs
, OID_AUTO
, lowmempgallocs
, CTLFLAG_RW
, &lowmempgallocs
, 0,
180 "Page allocations done during periods of very low free memory");
181 SYSCTL_UINT(_vfs
, OID_AUTO
, lowmempgfails
, CTLFLAG_RW
, &lowmempgfails
, 0,
182 "Page allocations which failed during periods of very low free memory");
183 SYSCTL_UINT(_vfs
, OID_AUTO
, vm_cycle_point
, CTLFLAG_RW
, &vm_cycle_point
, 0,
184 "Recycle pages to active or inactive queue transition pt 0-64");
186 * Sysctls determining current state of the buffer cache.
188 SYSCTL_LONG(_vfs
, OID_AUTO
, nbuf
, CTLFLAG_RD
, &nbuf
, 0,
189 "Total number of buffers in buffer cache");
190 SYSCTL_LONG(_vfs
, OID_AUTO
, dirtykvaspace
, CTLFLAG_RD
, &dirtykvaspace
, 0,
191 "KVA reserved by dirty buffers (all)");
192 SYSCTL_LONG(_vfs
, OID_AUTO
, dirtybufspace
, CTLFLAG_RD
, &dirtybufspace
, 0,
193 "Pending bytes of dirty buffers (all)");
194 SYSCTL_LONG(_vfs
, OID_AUTO
, dirtybufspacehw
, CTLFLAG_RD
, &dirtybufspacehw
, 0,
195 "Pending bytes of dirty buffers (heavy weight)");
196 SYSCTL_LONG(_vfs
, OID_AUTO
, dirtybufcount
, CTLFLAG_RD
, &dirtybufcount
, 0,
197 "Pending number of dirty buffers");
198 SYSCTL_LONG(_vfs
, OID_AUTO
, dirtybufcounthw
, CTLFLAG_RD
, &dirtybufcounthw
, 0,
199 "Pending number of dirty buffers (heavy weight)");
200 SYSCTL_LONG(_vfs
, OID_AUTO
, runningbufspace
, CTLFLAG_RD
, &runningbufspace
, 0,
201 "I/O bytes currently in progress due to asynchronous writes");
202 SYSCTL_LONG(_vfs
, OID_AUTO
, runningbufcount
, CTLFLAG_RD
, &runningbufcount
, 0,
203 "I/O buffers currently in progress due to asynchronous writes");
204 SYSCTL_LONG(_vfs
, OID_AUTO
, maxbufspace
, CTLFLAG_RD
, &maxbufspace
, 0,
205 "Hard limit on maximum amount of memory usable for buffer space");
206 SYSCTL_LONG(_vfs
, OID_AUTO
, hibufspace
, CTLFLAG_RD
, &hibufspace
, 0,
207 "Soft limit on maximum amount of memory usable for buffer space");
208 SYSCTL_LONG(_vfs
, OID_AUTO
, lobufspace
, CTLFLAG_RD
, &lobufspace
, 0,
209 "Minimum amount of memory to reserve for system buffer space");
210 SYSCTL_LONG(_vfs
, OID_AUTO
, bufspace
, CTLFLAG_RD
, &bufspace
, 0,
211 "Amount of memory available for buffers");
212 SYSCTL_LONG(_vfs
, OID_AUTO
, maxmallocbufspace
, CTLFLAG_RD
, &maxbufmallocspace
,
213 0, "Maximum amount of memory reserved for buffers using malloc");
214 SYSCTL_LONG(_vfs
, OID_AUTO
, bufmallocspace
, CTLFLAG_RD
, &bufmallocspace
, 0,
215 "Amount of memory left for buffers using malloc-scheme");
216 SYSCTL_INT(_vfs
, OID_AUTO
, getnewbufcalls
, CTLFLAG_RD
, &getnewbufcalls
, 0,
217 "New buffer header acquisition requests");
218 SYSCTL_INT(_vfs
, OID_AUTO
, getnewbufrestarts
, CTLFLAG_RD
, &getnewbufrestarts
,
219 0, "New buffer header acquisition restarts");
220 SYSCTL_INT(_vfs
, OID_AUTO
, recoverbufcalls
, CTLFLAG_RD
, &recoverbufcalls
, 0,
221 "Recover VM space in an emergency");
222 SYSCTL_INT(_vfs
, OID_AUTO
, bufdefragcnt
, CTLFLAG_RD
, &bufdefragcnt
, 0,
223 "Buffer acquisition restarts due to fragmented buffer map");
224 SYSCTL_INT(_vfs
, OID_AUTO
, buffreekvacnt
, CTLFLAG_RD
, &buffreekvacnt
, 0,
225 "Amount of time KVA space was deallocated in an arbitrary buffer");
226 SYSCTL_INT(_vfs
, OID_AUTO
, bufreusecnt
, CTLFLAG_RD
, &bufreusecnt
, 0,
227 "Amount of time buffer re-use operations were successful");
228 SYSCTL_INT(_vfs
, OID_AUTO
, debug_commit
, CTLFLAG_RW
, &debug_commit
, 0, "");
229 SYSCTL_INT(_vfs
, OID_AUTO
, debug_bufbio
, CTLFLAG_RW
, &debug_bufbio
, 0, "");
230 SYSCTL_INT(_debug_sizeof
, OID_AUTO
, buf
, CTLFLAG_RD
, 0, sizeof(struct buf
),
231 "sizeof(struct buf)");
233 char *buf_wmesg
= BUF_WMESG
;
235 #define VFS_BIO_NEED_ANY 0x01 /* any freeable buffer */
236 #define VFS_BIO_NEED_UNUSED02 0x02
237 #define VFS_BIO_NEED_UNUSED04 0x04
238 #define VFS_BIO_NEED_BUFSPACE 0x08 /* wait for buf space, lo hysteresis */
243 * Called when buffer space is potentially available for recovery.
244 * getnewbuf() will block on this flag when it is unable to free
245 * sufficient buffer space. Buffer space becomes recoverable when
246 * bp's get placed back in the queues.
252 * If someone is waiting for BUF space, wake them up. Even
253 * though we haven't freed the kva space yet, the waiting
254 * process will be able to now.
257 int flags
= needsbuffer
;
259 if ((flags
& VFS_BIO_NEED_BUFSPACE
) == 0)
261 if (atomic_cmpset_int(&needsbuffer
, flags
,
262 flags
& ~VFS_BIO_NEED_BUFSPACE
)) {
263 wakeup(&needsbuffer
);
273 * Accounting for I/O in progress.
277 runningbufwakeup(struct buf
*bp
)
282 if ((totalspace
= bp
->b_runningbufspace
) != 0) {
283 atomic_add_long(&runningbufspace
, -totalspace
);
284 atomic_add_long(&runningbufcount
, -1);
285 bp
->b_runningbufspace
= 0;
288 * see waitrunningbufspace() for limit test.
291 flags
= runningbufreq
;
295 if (atomic_cmpset_int(&runningbufreq
, flags
, 0)) {
296 wakeup(&runningbufreq
);
301 bd_signal(totalspace
);
308 * Called when a buffer has been added to one of the free queues to
309 * account for the buffer and to wakeup anyone waiting for free buffers.
310 * This typically occurs when large amounts of metadata are being handled
311 * by the buffer cache ( else buffer space runs out first, usually ).
322 if (atomic_cmpset_int(&needsbuffer
, flags
,
323 (flags
& ~VFS_BIO_NEED_ANY
))) {
324 wakeup(&needsbuffer
);
332 * waitrunningbufspace()
334 * If runningbufspace exceeds 4/6 hirunningspace we block until
335 * runningbufspace drops to 3/6 hirunningspace. We also block if another
336 * thread blocked here in order to be fair, even if runningbufspace
337 * is now lower than the limit.
339 * The caller may be using this function to block in a tight loop, we
340 * must block while runningbufspace is greater than at least
341 * hirunningspace * 3 / 6.
344 waitrunningbufspace(void)
346 long limit
= hirunningspace
* 4 / 6;
349 while (runningbufspace
> limit
|| runningbufreq
) {
350 tsleep_interlock(&runningbufreq
, 0);
351 flags
= atomic_fetchadd_int(&runningbufreq
, 1);
352 if (runningbufspace
> limit
|| flags
)
353 tsleep(&runningbufreq
, PINTERLOCKED
, "wdrn1", hz
);
358 * buf_dirty_count_severe:
360 * Return true if we have too many dirty buffers.
363 buf_dirty_count_severe(void)
365 return (runningbufspace
+ dirtykvaspace
>= hidirtybufspace
||
366 dirtybufcount
>= nbuf
/ 2);
370 * Return true if the amount of running I/O is severe and BIOQ should
374 buf_runningbufspace_severe(void)
376 return (runningbufspace
>= hirunningspace
* 4 / 6);
380 * vfs_buf_test_cache:
382 * Called when a buffer is extended. This function clears the B_CACHE
383 * bit if the newly extended portion of the buffer does not contain
386 * NOTE! Dirty VM pages are not processed into dirty (B_DELWRI) buffer
387 * cache buffers. The VM pages remain dirty, as someone had mmap()'d
388 * them while a clean buffer was present.
392 vfs_buf_test_cache(struct buf
*bp
,
393 vm_ooffset_t foff
, vm_offset_t off
, vm_offset_t size
,
396 if (bp
->b_flags
& B_CACHE
) {
397 int base
= (foff
+ off
) & PAGE_MASK
;
398 if (vm_page_is_valid(m
, base
, size
) == 0)
399 bp
->b_flags
&= ~B_CACHE
;
406 * Spank the buf_daemon[_hw] if the total dirty buffer space exceeds the
413 if (dirtykvaspace
< lodirtybufspace
&& dirtybufcount
< nbuf
/ 2)
416 if (bd_request
== 0 &&
417 (dirtykvaspace
> lodirtybufspace
/ 2 ||
418 dirtybufcount
- dirtybufcounthw
>= nbuf
/ 2)) {
419 if (atomic_fetchadd_int(&bd_request
, 1) == 0)
422 if (bd_request_hw
== 0 &&
423 (dirtykvaspace
> lodirtybufspace
/ 2 ||
424 dirtybufcounthw
>= nbuf
/ 2)) {
425 if (atomic_fetchadd_int(&bd_request_hw
, 1) == 0)
426 wakeup(&bd_request_hw
);
433 * Get the buf_daemon heated up when the number of running and dirty
434 * buffers exceeds the mid-point.
436 * Return the total number of dirty bytes past the second mid point
437 * as a measure of how much excess dirty data there is in the system.
446 mid1
= lodirtybufspace
+ (hidirtybufspace
- lodirtybufspace
) / 2;
448 totalspace
= runningbufspace
+ dirtykvaspace
;
449 if (totalspace
>= mid1
|| dirtybufcount
>= nbuf
/ 2) {
451 mid2
= mid1
+ (hidirtybufspace
- mid1
) / 2;
452 if (totalspace
>= mid2
)
453 return(totalspace
- mid2
);
461 * Wait for the buffer cache to flush (totalspace) bytes worth of
462 * buffers, then return.
464 * Regardless this function blocks while the number of dirty buffers
465 * exceeds hidirtybufspace.
468 bd_wait(long totalspace
)
475 if (curthread
== bufdaemonhw_td
|| curthread
== bufdaemon_td
)
478 while (totalspace
> 0) {
482 * Order is important. Suppliers adjust bd_wake_index after
483 * updating runningbufspace/dirtykvaspace. We want to fetch
484 * bd_wake_index before accessing. Any error should thus
487 i
= atomic_fetchadd_int(&bd_wake_index
, 0);
488 if (totalspace
> runningbufspace
+ dirtykvaspace
)
489 totalspace
= runningbufspace
+ dirtykvaspace
;
490 count
= totalspace
/ BKVASIZE
;
491 if (count
>= BD_WAKE_SIZE
/ 2)
492 count
= BD_WAKE_SIZE
/ 2;
494 mi
= i
& BD_WAKE_MASK
;
497 * This is not a strict interlock, so we play a bit loose
498 * with locking access to dirtybufspace*. We have to re-check
499 * bd_wake_index to ensure that it hasn't passed us.
501 tsleep_interlock(&bd_wake_ary
[mi
], 0);
502 atomic_add_int(&bd_wake_ary
[mi
], 1);
503 j
= atomic_fetchadd_int(&bd_wake_index
, 0);
504 if ((int)(i
- j
) >= 0)
505 tsleep(&bd_wake_ary
[mi
], PINTERLOCKED
, "flstik", hz
);
507 totalspace
= runningbufspace
+ dirtykvaspace
- hidirtybufspace
;
514 * This function is called whenever runningbufspace or dirtykvaspace
515 * is reduced. Track threads waiting for run+dirty buffer I/O
519 bd_signal(long totalspace
)
523 if (totalspace
> 0) {
524 if (totalspace
> BKVASIZE
* BD_WAKE_SIZE
)
525 totalspace
= BKVASIZE
* BD_WAKE_SIZE
;
526 while (totalspace
> 0) {
527 i
= atomic_fetchadd_int(&bd_wake_index
, 1);
529 if (atomic_readandclear_int(&bd_wake_ary
[i
]))
530 wakeup(&bd_wake_ary
[i
]);
531 totalspace
-= BKVASIZE
;
537 * BIO tracking support routines.
539 * Release a ref on a bio_track. Wakeup requests are atomically released
540 * along with the last reference so bk_active will never wind up set to
545 bio_track_rel(struct bio_track
*track
)
553 active
= track
->bk_active
;
554 if (active
== 1 && atomic_cmpset_int(&track
->bk_active
, 1, 0))
558 * Full-on. Note that the wait flag is only atomically released on
559 * the 1->0 count transition.
561 * We check for a negative count transition using bit 30 since bit 31
562 * has a different meaning.
565 desired
= (active
& 0x7FFFFFFF) - 1;
567 desired
|= active
& 0x80000000;
568 if (atomic_cmpset_int(&track
->bk_active
, active
, desired
)) {
569 if (desired
& 0x40000000)
570 panic("bio_track_rel: bad count: %p", track
);
571 if (active
& 0x80000000)
575 active
= track
->bk_active
;
580 * Wait for the tracking count to reach 0.
582 * Use atomic ops such that the wait flag is only set atomically when
583 * bk_active is non-zero.
586 bio_track_wait(struct bio_track
*track
, int slp_flags
, int slp_timo
)
595 if (track
->bk_active
== 0)
599 * Full-on. Note that the wait flag may only be atomically set if
600 * the active count is non-zero.
602 * NOTE: We cannot optimize active == desired since a wakeup could
603 * clear active prior to our tsleep_interlock().
606 while ((active
= track
->bk_active
) != 0) {
608 desired
= active
| 0x80000000;
609 tsleep_interlock(track
, slp_flags
);
610 if (atomic_cmpset_int(&track
->bk_active
, active
, desired
)) {
611 error
= tsleep(track
, slp_flags
| PINTERLOCKED
,
623 * Load time initialisation of the buffer cache, called from machine
624 * dependant initialization code.
628 bufinit(void *dummy __unused
)
630 struct bufpcpu
*pcpu
;
632 vm_offset_t bogus_offset
;
637 /* next, make a null set of free lists */
638 for (i
= 0; i
< ncpus
; ++i
) {
640 spin_init(&pcpu
->spin
, "bufinit");
641 for (j
= 0; j
< BUFFER_QUEUES
; j
++)
642 TAILQ_INIT(&pcpu
->bufqueues
[j
]);
645 /* finally, initialize each buffer header and stick on empty q */
649 for (n
= 0; n
< nbuf
; n
++) {
651 bzero(bp
, sizeof *bp
);
652 bp
->b_flags
= B_INVAL
; /* we're just an empty header */
653 bp
->b_cmd
= BUF_CMD_DONE
;
654 bp
->b_qindex
= BQUEUE_EMPTY
;
657 xio_init(&bp
->b_xio
);
659 TAILQ_INSERT_TAIL(&pcpu
->bufqueues
[bp
->b_qindex
],
667 * maxbufspace is the absolute maximum amount of buffer space we are
668 * allowed to reserve in KVM and in real terms. The absolute maximum
669 * is nominally used by buf_daemon. hibufspace is the nominal maximum
670 * used by most other processes. The differential is required to
671 * ensure that buf_daemon is able to run when other processes might
672 * be blocked waiting for buffer space.
674 * maxbufspace is based on BKVASIZE. Allocating buffers larger then
675 * this may result in KVM fragmentation which is not handled optimally
678 maxbufspace
= nbuf
* BKVASIZE
;
679 hibufspace
= lmax(3 * maxbufspace
/ 4, maxbufspace
- MAXBSIZE
* 10);
680 lobufspace
= hibufspace
- MAXBSIZE
;
682 lorunningspace
= 512 * 1024;
683 /* hirunningspace -- see below */
686 * Limit the amount of malloc memory since it is wired permanently
687 * into the kernel space. Even though this is accounted for in
688 * the buffer allocation, we don't want the malloced region to grow
689 * uncontrolled. The malloc scheme improves memory utilization
690 * significantly on average (small) directories.
692 maxbufmallocspace
= hibufspace
/ 20;
695 * Reduce the chance of a deadlock occuring by limiting the number
696 * of delayed-write dirty buffers we allow to stack up.
698 * We don't want too much actually queued to the device at once
699 * (XXX this needs to be per-mount!), because the buffers will
700 * wind up locked for a very long period of time while the I/O
703 hidirtybufspace
= hibufspace
/ 2; /* dirty + running */
704 hirunningspace
= hibufspace
/ 16; /* locked & queued to device */
705 if (hirunningspace
< 1024 * 1024)
706 hirunningspace
= 1024 * 1024;
712 lodirtybufspace
= hidirtybufspace
/ 2;
715 * Maximum number of async ops initiated per buf_daemon loop. This is
716 * somewhat of a hack at the moment, we really need to limit ourselves
717 * based on the number of bytes of I/O in-transit that were initiated
721 bogus_offset
= kmem_alloc_pageable(&kernel_map
, PAGE_SIZE
);
722 vm_object_hold(&kernel_object
);
723 bogus_page
= vm_page_alloc(&kernel_object
,
724 (bogus_offset
>> PAGE_SHIFT
),
726 vm_object_drop(&kernel_object
);
727 vmstats
.v_wire_count
++;
731 SYSINIT(do_bufinit
, SI_BOOT2_MACHDEP
, SI_ORDER_FIRST
, bufinit
, NULL
);
734 * Initialize the embedded bio structures, typically used by
735 * deprecated code which tries to allocate its own struct bufs.
738 initbufbio(struct buf
*bp
)
740 bp
->b_bio1
.bio_buf
= bp
;
741 bp
->b_bio1
.bio_prev
= NULL
;
742 bp
->b_bio1
.bio_offset
= NOOFFSET
;
743 bp
->b_bio1
.bio_next
= &bp
->b_bio2
;
744 bp
->b_bio1
.bio_done
= NULL
;
745 bp
->b_bio1
.bio_flags
= 0;
747 bp
->b_bio2
.bio_buf
= bp
;
748 bp
->b_bio2
.bio_prev
= &bp
->b_bio1
;
749 bp
->b_bio2
.bio_offset
= NOOFFSET
;
750 bp
->b_bio2
.bio_next
= NULL
;
751 bp
->b_bio2
.bio_done
= NULL
;
752 bp
->b_bio2
.bio_flags
= 0;
758 * Reinitialize the embedded bio structures as well as any additional
759 * translation cache layers.
762 reinitbufbio(struct buf
*bp
)
766 for (bio
= &bp
->b_bio1
; bio
; bio
= bio
->bio_next
) {
767 bio
->bio_done
= NULL
;
768 bio
->bio_offset
= NOOFFSET
;
773 * Undo the effects of an initbufbio().
776 uninitbufbio(struct buf
*bp
)
783 * Push another BIO layer onto an existing BIO and return it. The new
784 * BIO layer may already exist, holding cached translation data.
787 push_bio(struct bio
*bio
)
791 if ((nbio
= bio
->bio_next
) == NULL
) {
792 int index
= bio
- &bio
->bio_buf
->b_bio_array
[0];
793 if (index
>= NBUF_BIO
- 1) {
794 panic("push_bio: too many layers %d for bp %p",
795 index
, bio
->bio_buf
);
797 nbio
= &bio
->bio_buf
->b_bio_array
[index
+ 1];
798 bio
->bio_next
= nbio
;
799 nbio
->bio_prev
= bio
;
800 nbio
->bio_buf
= bio
->bio_buf
;
801 nbio
->bio_offset
= NOOFFSET
;
802 nbio
->bio_done
= NULL
;
803 nbio
->bio_next
= NULL
;
805 KKASSERT(nbio
->bio_done
== NULL
);
810 * Pop a BIO translation layer, returning the previous layer. The
811 * must have been previously pushed.
814 pop_bio(struct bio
*bio
)
816 return(bio
->bio_prev
);
820 clearbiocache(struct bio
*bio
)
823 bio
->bio_offset
= NOOFFSET
;
831 * Free the KVA allocation for buffer 'bp'.
833 * Must be called from a critical section as this is the only locking for
836 * Since this call frees up buffer space, we call bufspacewakeup().
839 bfreekva(struct buf
*bp
)
845 count
= vm_map_entry_reserve(MAP_RESERVE_COUNT
);
846 vm_map_lock(&buffer_map
);
847 bufspace
-= bp
->b_kvasize
;
848 vm_map_delete(&buffer_map
,
849 (vm_offset_t
) bp
->b_kvabase
,
850 (vm_offset_t
) bp
->b_kvabase
+ bp
->b_kvasize
,
853 vm_map_unlock(&buffer_map
);
854 vm_map_entry_release(count
);
856 bp
->b_kvabase
= NULL
;
862 * Remove the buffer from the appropriate free list.
863 * (caller must be locked)
866 _bremfree(struct buf
*bp
)
868 struct bufpcpu
*pcpu
= &bufpcpu
[bp
->b_qcpu
];
870 if (bp
->b_qindex
!= BQUEUE_NONE
) {
871 KASSERT(BUF_REFCNTNB(bp
) == 1,
872 ("bremfree: bp %p not locked",bp
));
873 TAILQ_REMOVE(&pcpu
->bufqueues
[bp
->b_qindex
], bp
, b_freelist
);
874 bp
->b_qindex
= BQUEUE_NONE
;
876 if (BUF_REFCNTNB(bp
) <= 1)
877 panic("bremfree: removing a buffer not on a queue");
882 * bremfree() - must be called with a locked buffer
885 bremfree(struct buf
*bp
)
887 struct bufpcpu
*pcpu
= &bufpcpu
[bp
->b_qcpu
];
889 spin_lock(&pcpu
->spin
);
891 spin_unlock(&pcpu
->spin
);
895 * bremfree_locked - must be called with pcpu->spin locked
898 bremfree_locked(struct buf
*bp
)
904 * This version of bread issues any required I/O asyncnronously and
905 * makes a callback on completion.
907 * The callback must check whether BIO_DONE is set in the bio and issue
908 * the bpdone(bp, 0) if it isn't. The callback is responsible for clearing
909 * BIO_DONE and disposing of the I/O (bqrelse()ing it).
912 breadcb(struct vnode
*vp
, off_t loffset
, int size
,
913 void (*func
)(struct bio
*), void *arg
)
917 bp
= getblk(vp
, loffset
, size
, 0, 0);
919 /* if not found in cache, do some I/O */
920 if ((bp
->b_flags
& B_CACHE
) == 0) {
921 bp
->b_flags
&= ~(B_ERROR
| B_EINTR
| B_INVAL
);
922 bp
->b_cmd
= BUF_CMD_READ
;
923 bp
->b_bio1
.bio_done
= func
;
924 bp
->b_bio1
.bio_caller_info1
.ptr
= arg
;
925 vfs_busy_pages(vp
, bp
);
927 vn_strategy(vp
, &bp
->b_bio1
);
930 * Since we are issuing the callback synchronously it cannot
931 * race the BIO_DONE, so no need for atomic ops here.
933 /*bp->b_bio1.bio_done = func;*/
934 bp
->b_bio1
.bio_caller_info1
.ptr
= arg
;
935 bp
->b_bio1
.bio_flags
|= BIO_DONE
;
943 * breadnx() - Terminal function for bread() and breadn().
945 * This function will start asynchronous I/O on read-ahead blocks as well
946 * as satisfy the primary request.
948 * We must clear B_ERROR and B_INVAL prior to initiating I/O. If B_CACHE is
949 * set, the buffer is valid and we do not have to do anything.
952 breadnx(struct vnode
*vp
, off_t loffset
, int size
, off_t
*raoffset
,
953 int *rabsize
, int cnt
, struct buf
**bpp
)
955 struct buf
*bp
, *rabp
;
957 int rv
= 0, readwait
= 0;
962 *bpp
= bp
= getblk(vp
, loffset
, size
, 0, 0);
964 /* if not found in cache, do some I/O */
965 if ((bp
->b_flags
& B_CACHE
) == 0) {
966 bp
->b_flags
&= ~(B_ERROR
| B_EINTR
| B_INVAL
);
967 bp
->b_cmd
= BUF_CMD_READ
;
968 bp
->b_bio1
.bio_done
= biodone_sync
;
969 bp
->b_bio1
.bio_flags
|= BIO_SYNC
;
970 vfs_busy_pages(vp
, bp
);
971 vn_strategy(vp
, &bp
->b_bio1
);
975 for (i
= 0; i
< cnt
; i
++, raoffset
++, rabsize
++) {
976 if (inmem(vp
, *raoffset
))
978 rabp
= getblk(vp
, *raoffset
, *rabsize
, 0, 0);
980 if ((rabp
->b_flags
& B_CACHE
) == 0) {
981 rabp
->b_flags
&= ~(B_ERROR
| B_EINTR
| B_INVAL
);
982 rabp
->b_cmd
= BUF_CMD_READ
;
983 vfs_busy_pages(vp
, rabp
);
985 vn_strategy(vp
, &rabp
->b_bio1
);
991 rv
= biowait(&bp
->b_bio1
, "biord");
998 * Synchronous write, waits for completion.
1000 * Write, release buffer on completion. (Done by iodone
1001 * if async). Do not bother writing anything if the buffer
1004 * Note that we set B_CACHE here, indicating that buffer is
1005 * fully valid and thus cacheable. This is true even of NFS
1006 * now so we set it generally. This could be set either here
1007 * or in biodone() since the I/O is synchronous. We put it
1011 bwrite(struct buf
*bp
)
1015 if (bp
->b_flags
& B_INVAL
) {
1019 if (BUF_REFCNTNB(bp
) == 0)
1020 panic("bwrite: buffer is not busy???");
1023 * NOTE: We no longer mark the buffer clear prior to the vn_strategy()
1024 * call because it will remove the buffer from the vnode's
1025 * dirty buffer list prematurely and possibly cause filesystem
1026 * checks to race buffer flushes. This is now handled in
1029 * bundirty(bp); REMOVED
1032 bp
->b_flags
&= ~(B_ERROR
| B_EINTR
);
1033 bp
->b_flags
|= B_CACHE
;
1034 bp
->b_cmd
= BUF_CMD_WRITE
;
1035 bp
->b_bio1
.bio_done
= biodone_sync
;
1036 bp
->b_bio1
.bio_flags
|= BIO_SYNC
;
1037 vfs_busy_pages(bp
->b_vp
, bp
);
1040 * Normal bwrites pipeline writes. NOTE: b_bufsize is only
1041 * valid for vnode-backed buffers.
1043 bsetrunningbufspace(bp
, bp
->b_bufsize
);
1044 vn_strategy(bp
->b_vp
, &bp
->b_bio1
);
1045 error
= biowait(&bp
->b_bio1
, "biows");
1054 * Asynchronous write. Start output on a buffer, but do not wait for
1055 * it to complete. The buffer is released when the output completes.
1057 * bwrite() ( or the VOP routine anyway ) is responsible for handling
1058 * B_INVAL buffers. Not us.
1061 bawrite(struct buf
*bp
)
1063 if (bp
->b_flags
& B_INVAL
) {
1067 if (BUF_REFCNTNB(bp
) == 0)
1068 panic("bawrite: buffer is not busy???");
1071 * NOTE: We no longer mark the buffer clear prior to the vn_strategy()
1072 * call because it will remove the buffer from the vnode's
1073 * dirty buffer list prematurely and possibly cause filesystem
1074 * checks to race buffer flushes. This is now handled in
1077 * bundirty(bp); REMOVED
1079 bp
->b_flags
&= ~(B_ERROR
| B_EINTR
);
1080 bp
->b_flags
|= B_CACHE
;
1081 bp
->b_cmd
= BUF_CMD_WRITE
;
1082 KKASSERT(bp
->b_bio1
.bio_done
== NULL
);
1083 vfs_busy_pages(bp
->b_vp
, bp
);
1086 * Normal bwrites pipeline writes. NOTE: b_bufsize is only
1087 * valid for vnode-backed buffers.
1089 bsetrunningbufspace(bp
, bp
->b_bufsize
);
1091 vn_strategy(bp
->b_vp
, &bp
->b_bio1
);
1097 * Ordered write. Start output on a buffer, and flag it so that the
1098 * device will write it in the order it was queued. The buffer is
1099 * released when the output completes. bwrite() ( or the VOP routine
1100 * anyway ) is responsible for handling B_INVAL buffers.
1103 bowrite(struct buf
*bp
)
1105 bp
->b_flags
|= B_ORDERED
;
1113 * Delayed write. (Buffer is marked dirty). Do not bother writing
1114 * anything if the buffer is marked invalid.
1116 * Note that since the buffer must be completely valid, we can safely
1117 * set B_CACHE. In fact, we have to set B_CACHE here rather then in
1118 * biodone() in order to prevent getblk from writing the buffer
1119 * out synchronously.
1122 bdwrite(struct buf
*bp
)
1124 if (BUF_REFCNTNB(bp
) == 0)
1125 panic("bdwrite: buffer is not busy");
1127 if (bp
->b_flags
& B_INVAL
) {
1133 dsched_buf_enter(bp
); /* might stack */
1136 * Set B_CACHE, indicating that the buffer is fully valid. This is
1137 * true even of NFS now.
1139 bp
->b_flags
|= B_CACHE
;
1142 * This bmap keeps the system from needing to do the bmap later,
1143 * perhaps when the system is attempting to do a sync. Since it
1144 * is likely that the indirect block -- or whatever other datastructure
1145 * that the filesystem needs is still in memory now, it is a good
1146 * thing to do this. Note also, that if the pageout daemon is
1147 * requesting a sync -- there might not be enough memory to do
1148 * the bmap then... So, this is important to do.
1150 if (bp
->b_bio2
.bio_offset
== NOOFFSET
) {
1151 VOP_BMAP(bp
->b_vp
, bp
->b_loffset
, &bp
->b_bio2
.bio_offset
,
1152 NULL
, NULL
, BUF_CMD_WRITE
);
1156 * Because the underlying pages may still be mapped and
1157 * writable trying to set the dirty buffer (b_dirtyoff/end)
1158 * range here will be inaccurate.
1160 * However, we must still clean the pages to satisfy the
1161 * vnode_pager and pageout daemon, so they think the pages
1162 * have been "cleaned". What has really occured is that
1163 * they've been earmarked for later writing by the buffer
1166 * So we get the b_dirtyoff/end update but will not actually
1167 * depend on it (NFS that is) until the pages are busied for
1170 vfs_clean_pages(bp
);
1174 * note: we cannot initiate I/O from a bdwrite even if we wanted to,
1175 * due to the softdep code.
1180 * Fake write - return pages to VM system as dirty, leave the buffer clean.
1181 * This is used by tmpfs.
1183 * It is important for any VFS using this routine to NOT use it for
1184 * IO_SYNC or IO_ASYNC operations which occur when the system really
1185 * wants to flush VM pages to backing store.
1188 buwrite(struct buf
*bp
)
1194 * Only works for VMIO buffers. If the buffer is already
1195 * marked for delayed-write we can't avoid the bdwrite().
1197 if ((bp
->b_flags
& B_VMIO
) == 0 || (bp
->b_flags
& B_DELWRI
)) {
1203 * Mark as needing a commit.
1205 for (i
= 0; i
< bp
->b_xio
.xio_npages
; i
++) {
1206 m
= bp
->b_xio
.xio_pages
[i
];
1207 vm_page_need_commit(m
);
1215 * Turn buffer into delayed write request by marking it B_DELWRI.
1216 * B_RELBUF and B_NOCACHE must be cleared.
1218 * We reassign the buffer to itself to properly update it in the
1219 * dirty/clean lists.
1221 * Must be called from a critical section.
1222 * The buffer must be on BQUEUE_NONE.
1225 bdirty(struct buf
*bp
)
1227 KASSERT(bp
->b_qindex
== BQUEUE_NONE
,
1228 ("bdirty: buffer %p still on queue %d", bp
, bp
->b_qindex
));
1229 if (bp
->b_flags
& B_NOCACHE
) {
1230 kprintf("bdirty: clearing B_NOCACHE on buf %p\n", bp
);
1231 bp
->b_flags
&= ~B_NOCACHE
;
1233 if (bp
->b_flags
& B_INVAL
) {
1234 kprintf("bdirty: warning, dirtying invalid buffer %p\n", bp
);
1236 bp
->b_flags
&= ~B_RELBUF
;
1238 if ((bp
->b_flags
& B_DELWRI
) == 0) {
1239 lwkt_gettoken(&bp
->b_vp
->v_token
);
1240 bp
->b_flags
|= B_DELWRI
;
1242 lwkt_reltoken(&bp
->b_vp
->v_token
);
1244 atomic_add_long(&dirtybufcount
, 1);
1245 atomic_add_long(&dirtykvaspace
, bp
->b_kvasize
);
1246 atomic_add_long(&dirtybufspace
, bp
->b_bufsize
);
1247 if (bp
->b_flags
& B_HEAVY
) {
1248 atomic_add_long(&dirtybufcounthw
, 1);
1249 atomic_add_long(&dirtybufspacehw
, bp
->b_bufsize
);
1256 * Set B_HEAVY, indicating that this is a heavy-weight buffer that
1257 * needs to be flushed with a different buf_daemon thread to avoid
1258 * deadlocks. B_HEAVY also imposes restrictions in getnewbuf().
1261 bheavy(struct buf
*bp
)
1263 if ((bp
->b_flags
& B_HEAVY
) == 0) {
1264 bp
->b_flags
|= B_HEAVY
;
1265 if (bp
->b_flags
& B_DELWRI
) {
1266 atomic_add_long(&dirtybufcounthw
, 1);
1267 atomic_add_long(&dirtybufspacehw
, bp
->b_bufsize
);
1275 * Clear B_DELWRI for buffer.
1277 * Must be called from a critical section.
1279 * The buffer is typically on BQUEUE_NONE but there is one case in
1280 * brelse() that calls this function after placing the buffer on
1281 * a different queue.
1284 bundirty(struct buf
*bp
)
1286 if (bp
->b_flags
& B_DELWRI
) {
1287 lwkt_gettoken(&bp
->b_vp
->v_token
);
1288 bp
->b_flags
&= ~B_DELWRI
;
1290 lwkt_reltoken(&bp
->b_vp
->v_token
);
1292 atomic_add_long(&dirtybufcount
, -1);
1293 atomic_add_long(&dirtykvaspace
, -bp
->b_kvasize
);
1294 atomic_add_long(&dirtybufspace
, -bp
->b_bufsize
);
1295 if (bp
->b_flags
& B_HEAVY
) {
1296 atomic_add_long(&dirtybufcounthw
, -1);
1297 atomic_add_long(&dirtybufspacehw
, -bp
->b_bufsize
);
1299 bd_signal(bp
->b_bufsize
);
1302 * Since it is now being written, we can clear its deferred write flag.
1304 bp
->b_flags
&= ~B_DEFERRED
;
1308 * Set the b_runningbufspace field, used to track how much I/O is
1309 * in progress at any given moment.
1312 bsetrunningbufspace(struct buf
*bp
, int bytes
)
1314 bp
->b_runningbufspace
= bytes
;
1316 atomic_add_long(&runningbufspace
, bytes
);
1317 atomic_add_long(&runningbufcount
, 1);
1324 * Release a busy buffer and, if requested, free its resources. The
1325 * buffer will be stashed in the appropriate bufqueue[] allowing it
1326 * to be accessed later as a cache entity or reused for other purposes.
1329 brelse(struct buf
*bp
)
1331 struct bufpcpu
*pcpu
;
1333 int saved_flags
= bp
->b_flags
;
1336 KASSERT(!(bp
->b_flags
& (B_CLUSTER
|B_PAGING
)),
1337 ("brelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp
));
1340 * If B_NOCACHE is set we are being asked to destroy the buffer and
1341 * its backing store. Clear B_DELWRI.
1343 * B_NOCACHE is set in two cases: (1) when the caller really wants
1344 * to destroy the buffer and backing store and (2) when the caller
1345 * wants to destroy the buffer and backing store after a write
1348 if ((bp
->b_flags
& (B_NOCACHE
|B_DELWRI
)) == (B_NOCACHE
|B_DELWRI
)) {
1352 if ((bp
->b_flags
& (B_INVAL
| B_DELWRI
)) == B_DELWRI
) {
1354 * A re-dirtied buffer is only subject to destruction
1355 * by B_INVAL. B_ERROR and B_NOCACHE are ignored.
1357 /* leave buffer intact */
1358 } else if ((bp
->b_flags
& (B_NOCACHE
| B_INVAL
| B_ERROR
)) ||
1359 (bp
->b_bufsize
<= 0)) {
1361 * Either a failed read or we were asked to free or not
1362 * cache the buffer. This path is reached with B_DELWRI
1363 * set only if B_INVAL is already set. B_NOCACHE governs
1364 * backing store destruction.
1366 * NOTE: HAMMER will set B_LOCKED in buf_deallocate if the
1367 * buffer cannot be immediately freed.
1369 bp
->b_flags
|= B_INVAL
;
1370 if (LIST_FIRST(&bp
->b_dep
) != NULL
)
1372 if (bp
->b_flags
& B_DELWRI
) {
1373 atomic_add_long(&dirtybufcount
, -1);
1374 atomic_add_long(&dirtykvaspace
, -bp
->b_kvasize
);
1375 atomic_add_long(&dirtybufspace
, -bp
->b_bufsize
);
1376 if (bp
->b_flags
& B_HEAVY
) {
1377 atomic_add_long(&dirtybufcounthw
, -1);
1378 atomic_add_long(&dirtybufspacehw
,
1381 bd_signal(bp
->b_bufsize
);
1383 bp
->b_flags
&= ~(B_DELWRI
| B_CACHE
);
1387 * We must clear B_RELBUF if B_DELWRI or B_LOCKED is set,
1388 * or if b_refs is non-zero.
1390 * If vfs_vmio_release() is called with either bit set, the
1391 * underlying pages may wind up getting freed causing a previous
1392 * write (bdwrite()) to get 'lost' because pages associated with
1393 * a B_DELWRI bp are marked clean. Pages associated with a
1394 * B_LOCKED buffer may be mapped by the filesystem.
1396 * If we want to release the buffer ourselves (rather then the
1397 * originator asking us to release it), give the originator a
1398 * chance to countermand the release by setting B_LOCKED.
1400 * We still allow the B_INVAL case to call vfs_vmio_release(), even
1401 * if B_DELWRI is set.
1403 * If B_DELWRI is not set we may have to set B_RELBUF if we are low
1404 * on pages to return pages to the VM page queues.
1406 if ((bp
->b_flags
& (B_DELWRI
| B_LOCKED
)) || bp
->b_refs
) {
1407 bp
->b_flags
&= ~B_RELBUF
;
1408 } else if (vm_page_count_min(0)) {
1409 if (LIST_FIRST(&bp
->b_dep
) != NULL
)
1410 buf_deallocate(bp
); /* can set B_LOCKED */
1411 if (bp
->b_flags
& (B_DELWRI
| B_LOCKED
))
1412 bp
->b_flags
&= ~B_RELBUF
;
1414 bp
->b_flags
|= B_RELBUF
;
1418 * Make sure b_cmd is clear. It may have already been cleared by
1421 * At this point destroying the buffer is governed by the B_INVAL
1422 * or B_RELBUF flags.
1424 bp
->b_cmd
= BUF_CMD_DONE
;
1425 dsched_buf_exit(bp
);
1428 * VMIO buffer rundown. Make sure the VM page array is restored
1429 * after an I/O may have replaces some of the pages with bogus pages
1430 * in order to not destroy dirty pages in a fill-in read.
1432 * Note that due to the code above, if a buffer is marked B_DELWRI
1433 * then the B_RELBUF and B_NOCACHE bits will always be clear.
1434 * B_INVAL may still be set, however.
1436 * For clean buffers, B_INVAL or B_RELBUF will destroy the buffer
1437 * but not the backing store. B_NOCACHE will destroy the backing
1440 * Note that dirty NFS buffers contain byte-granular write ranges
1441 * and should not be destroyed w/ B_INVAL even if the backing store
1444 if (bp
->b_flags
& B_VMIO
) {
1446 * Rundown for VMIO buffers which are not dirty NFS buffers.
1458 * Get the base offset and length of the buffer. Note that
1459 * in the VMIO case if the buffer block size is not
1460 * page-aligned then b_data pointer may not be page-aligned.
1461 * But our b_xio.xio_pages array *IS* page aligned.
1463 * block sizes less then DEV_BSIZE (usually 512) are not
1464 * supported due to the page granularity bits (m->valid,
1465 * m->dirty, etc...).
1467 * See man buf(9) for more information
1470 resid
= bp
->b_bufsize
;
1471 foff
= bp
->b_loffset
;
1473 for (i
= 0; i
< bp
->b_xio
.xio_npages
; i
++) {
1474 m
= bp
->b_xio
.xio_pages
[i
];
1475 vm_page_flag_clear(m
, PG_ZERO
);
1477 * If we hit a bogus page, fixup *all* of them
1478 * now. Note that we left these pages wired
1479 * when we removed them so they had better exist,
1480 * and they cannot be ripped out from under us so
1481 * no critical section protection is necessary.
1483 if (m
== bogus_page
) {
1485 poff
= OFF_TO_IDX(bp
->b_loffset
);
1487 vm_object_hold(obj
);
1488 for (j
= i
; j
< bp
->b_xio
.xio_npages
; j
++) {
1491 mtmp
= bp
->b_xio
.xio_pages
[j
];
1492 if (mtmp
== bogus_page
) {
1493 mtmp
= vm_page_lookup(obj
, poff
+ j
);
1495 panic("brelse: page missing");
1497 bp
->b_xio
.xio_pages
[j
] = mtmp
;
1500 bp
->b_flags
&= ~B_HASBOGUS
;
1501 vm_object_drop(obj
);
1503 if ((bp
->b_flags
& B_INVAL
) == 0) {
1504 pmap_qenter(trunc_page((vm_offset_t
)bp
->b_data
),
1505 bp
->b_xio
.xio_pages
, bp
->b_xio
.xio_npages
);
1507 m
= bp
->b_xio
.xio_pages
[i
];
1511 * Invalidate the backing store if B_NOCACHE is set
1512 * (e.g. used with vinvalbuf()). If this is NFS
1513 * we impose a requirement that the block size be
1514 * a multiple of PAGE_SIZE and create a temporary
1515 * hack to basically invalidate the whole page. The
1516 * problem is that NFS uses really odd buffer sizes
1517 * especially when tracking piecemeal writes and
1518 * it also vinvalbuf()'s a lot, which would result
1519 * in only partial page validation and invalidation
1520 * here. If the file page is mmap()'d, however,
1521 * all the valid bits get set so after we invalidate
1522 * here we would end up with weird m->valid values
1523 * like 0xfc. nfs_getpages() can't handle this so
1524 * we clear all the valid bits for the NFS case
1525 * instead of just some of them.
1527 * The real bug is the VM system having to set m->valid
1528 * to VM_PAGE_BITS_ALL for faulted-in pages, which
1529 * itself is an artifact of the whole 512-byte
1530 * granular mess that exists to support odd block
1531 * sizes and UFS meta-data block sizes (e.g. 6144).
1532 * A complete rewrite is required.
1536 if (bp
->b_flags
& (B_NOCACHE
|B_ERROR
)) {
1537 int poffset
= foff
& PAGE_MASK
;
1540 presid
= PAGE_SIZE
- poffset
;
1541 if (bp
->b_vp
->v_tag
== VT_NFS
&&
1542 bp
->b_vp
->v_type
== VREG
) {
1544 } else if (presid
> resid
) {
1547 KASSERT(presid
>= 0, ("brelse: extra page"));
1548 vm_page_set_invalid(m
, poffset
, presid
);
1551 * Also make sure any swap cache is removed
1552 * as it is now stale (HAMMER in particular
1553 * uses B_NOCACHE to deal with buffer
1556 swap_pager_unswapped(m
);
1558 resid
-= PAGE_SIZE
- (foff
& PAGE_MASK
);
1559 foff
= (foff
+ PAGE_SIZE
) & ~(off_t
)PAGE_MASK
;
1561 if (bp
->b_flags
& (B_INVAL
| B_RELBUF
))
1562 vfs_vmio_release(bp
);
1565 * Rundown for non-VMIO buffers.
1567 if (bp
->b_flags
& (B_INVAL
| B_RELBUF
)) {
1570 KKASSERT (LIST_FIRST(&bp
->b_dep
) == NULL
);
1576 if (bp
->b_qindex
!= BQUEUE_NONE
)
1577 panic("brelse: free buffer onto another queue???");
1578 if (BUF_REFCNTNB(bp
) > 1) {
1579 /* Temporary panic to verify exclusive locking */
1580 /* This panic goes away when we allow shared refs */
1581 panic("brelse: multiple refs");
1587 * Figure out the correct queue to place the cleaned up buffer on.
1588 * Buffers placed in the EMPTY or EMPTYKVA had better already be
1589 * disassociated from their vnode.
1591 * Return the buffer to its original pcpu area
1593 pcpu
= &bufpcpu
[bp
->b_qcpu
];
1594 spin_lock(&pcpu
->spin
);
1596 if (bp
->b_flags
& B_LOCKED
) {
1598 * Buffers that are locked are placed in the locked queue
1599 * immediately, regardless of their state.
1601 bp
->b_qindex
= BQUEUE_LOCKED
;
1602 TAILQ_INSERT_TAIL(&pcpu
->bufqueues
[bp
->b_qindex
],
1604 } else if (bp
->b_bufsize
== 0) {
1606 * Buffers with no memory. Due to conditionals near the top
1607 * of brelse() such buffers should probably already be
1608 * marked B_INVAL and disassociated from their vnode.
1610 bp
->b_flags
|= B_INVAL
;
1611 KASSERT(bp
->b_vp
== NULL
,
1612 ("bp1 %p flags %08x/%08x vnode %p "
1613 "unexpectededly still associated!",
1614 bp
, saved_flags
, bp
->b_flags
, bp
->b_vp
));
1615 KKASSERT((bp
->b_flags
& B_HASHED
) == 0);
1616 if (bp
->b_kvasize
) {
1617 bp
->b_qindex
= BQUEUE_EMPTYKVA
;
1619 bp
->b_qindex
= BQUEUE_EMPTY
;
1621 TAILQ_INSERT_HEAD(&pcpu
->bufqueues
[bp
->b_qindex
],
1623 } else if (bp
->b_flags
& (B_INVAL
| B_NOCACHE
| B_RELBUF
)) {
1625 * Buffers with junk contents. Again these buffers had better
1626 * already be disassociated from their vnode.
1628 KASSERT(bp
->b_vp
== NULL
,
1629 ("bp2 %p flags %08x/%08x vnode %p unexpectededly "
1630 "still associated!",
1631 bp
, saved_flags
, bp
->b_flags
, bp
->b_vp
));
1632 KKASSERT((bp
->b_flags
& B_HASHED
) == 0);
1633 bp
->b_flags
|= B_INVAL
;
1634 bp
->b_qindex
= BQUEUE_CLEAN
;
1635 TAILQ_INSERT_HEAD(&pcpu
->bufqueues
[bp
->b_qindex
],
1639 * Remaining buffers. These buffers are still associated with
1642 switch(bp
->b_flags
& (B_DELWRI
|B_HEAVY
)) {
1644 bp
->b_qindex
= BQUEUE_DIRTY
;
1645 TAILQ_INSERT_TAIL(&pcpu
->bufqueues
[bp
->b_qindex
],
1648 case B_DELWRI
| B_HEAVY
:
1649 bp
->b_qindex
= BQUEUE_DIRTY_HW
;
1650 TAILQ_INSERT_TAIL(&pcpu
->bufqueues
[bp
->b_qindex
],
1655 * NOTE: Buffers are always placed at the end of the
1656 * queue. If B_AGE is not set the buffer will cycle
1657 * through the queue twice.
1659 bp
->b_qindex
= BQUEUE_CLEAN
;
1660 TAILQ_INSERT_TAIL(&pcpu
->bufqueues
[bp
->b_qindex
],
1665 spin_unlock(&pcpu
->spin
);
1668 * If B_INVAL, clear B_DELWRI. We've already placed the buffer
1669 * on the correct queue but we have not yet unlocked it.
1671 if ((bp
->b_flags
& (B_INVAL
|B_DELWRI
)) == (B_INVAL
|B_DELWRI
))
1675 * The bp is on an appropriate queue unless locked. If it is not
1676 * locked or dirty we can wakeup threads waiting for buffer space.
1678 * We've already handled the B_INVAL case ( B_DELWRI will be clear
1679 * if B_INVAL is set ).
1681 if ((bp
->b_flags
& (B_LOCKED
|B_DELWRI
)) == 0)
1685 * Something we can maybe free or reuse
1687 if (bp
->b_bufsize
|| bp
->b_kvasize
)
1691 * Clean up temporary flags and unlock the buffer.
1693 bp
->b_flags
&= ~(B_ORDERED
| B_NOCACHE
| B_RELBUF
| B_DIRECT
);
1700 * Release a buffer back to the appropriate queue but do not try to free
1701 * it. The buffer is expected to be used again soon.
1703 * bqrelse() is used by bdwrite() to requeue a delayed write, and used by
1704 * biodone() to requeue an async I/O on completion. It is also used when
1705 * known good buffers need to be requeued but we think we may need the data
1708 * XXX we should be able to leave the B_RELBUF hint set on completion.
1711 bqrelse(struct buf
*bp
)
1713 struct bufpcpu
*pcpu
;
1715 KASSERT(!(bp
->b_flags
& (B_CLUSTER
|B_PAGING
)),
1716 ("bqrelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp
));
1718 if (bp
->b_qindex
!= BQUEUE_NONE
)
1719 panic("bqrelse: free buffer onto another queue???");
1720 if (BUF_REFCNTNB(bp
) > 1) {
1721 /* do not release to free list */
1722 panic("bqrelse: multiple refs");
1726 buf_act_advance(bp
);
1728 pcpu
= &bufpcpu
[bp
->b_qcpu
];
1729 spin_lock(&pcpu
->spin
);
1731 if (bp
->b_flags
& B_LOCKED
) {
1733 * Locked buffers are released to the locked queue. However,
1734 * if the buffer is dirty it will first go into the dirty
1735 * queue and later on after the I/O completes successfully it
1736 * will be released to the locked queue.
1738 bp
->b_qindex
= BQUEUE_LOCKED
;
1739 TAILQ_INSERT_TAIL(&pcpu
->bufqueues
[bp
->b_qindex
],
1741 } else if (bp
->b_flags
& B_DELWRI
) {
1742 bp
->b_qindex
= (bp
->b_flags
& B_HEAVY
) ?
1743 BQUEUE_DIRTY_HW
: BQUEUE_DIRTY
;
1744 TAILQ_INSERT_TAIL(&pcpu
->bufqueues
[bp
->b_qindex
],
1746 } else if (vm_page_count_min(0)) {
1748 * We are too low on memory, we have to try to free the
1749 * buffer (most importantly: the wired pages making up its
1750 * backing store) *now*.
1752 spin_unlock(&pcpu
->spin
);
1756 bp
->b_qindex
= BQUEUE_CLEAN
;
1757 TAILQ_INSERT_TAIL(&pcpu
->bufqueues
[bp
->b_qindex
],
1760 spin_unlock(&pcpu
->spin
);
1763 * We have now placed the buffer on the proper queue, but have yet
1766 if ((bp
->b_flags
& B_LOCKED
) == 0 &&
1767 ((bp
->b_flags
& B_INVAL
) || (bp
->b_flags
& B_DELWRI
) == 0)) {
1772 * Something we can maybe free or reuse.
1774 if (bp
->b_bufsize
&& !(bp
->b_flags
& B_DELWRI
))
1778 * Final cleanup and unlock. Clear bits that are only used while a
1779 * buffer is actively locked.
1781 bp
->b_flags
&= ~(B_ORDERED
| B_NOCACHE
| B_RELBUF
);
1782 dsched_buf_exit(bp
);
1787 * Hold a buffer, preventing it from being reused. This will prevent
1788 * normal B_RELBUF operations on the buffer but will not prevent B_INVAL
1789 * operations. If a B_INVAL operation occurs the buffer will remain held
1790 * but the underlying pages may get ripped out.
1792 * These functions are typically used in VOP_READ/VOP_WRITE functions
1793 * to hold a buffer during a copyin or copyout, preventing deadlocks
1794 * or recursive lock panics when read()/write() is used over mmap()'d
1797 * NOTE: bqhold() requires that the buffer be locked at the time of the
1798 * hold. bqdrop() has no requirements other than the buffer having
1799 * previously been held.
1802 bqhold(struct buf
*bp
)
1804 atomic_add_int(&bp
->b_refs
, 1);
1808 bqdrop(struct buf
*bp
)
1810 KKASSERT(bp
->b_refs
> 0);
1811 atomic_add_int(&bp
->b_refs
, -1);
1815 * Return backing pages held by the buffer 'bp' back to the VM system.
1816 * This routine is called when the bp is invalidated, released, or
1819 * The KVA mapping (b_data) for the underlying pages is removed by
1822 * WARNING! This routine is integral to the low memory critical path
1823 * when a buffer is B_RELBUF'd. If the system has a severe page
1824 * deficit we need to get the page(s) onto the PQ_FREE or PQ_CACHE
1825 * queues so they can be reused in the current pageout daemon
1829 vfs_vmio_release(struct buf
*bp
)
1834 for (i
= 0; i
< bp
->b_xio
.xio_npages
; i
++) {
1835 m
= bp
->b_xio
.xio_pages
[i
];
1836 bp
->b_xio
.xio_pages
[i
] = NULL
;
1839 * We need to own the page in order to safely unwire it.
1841 vm_page_busy_wait(m
, FALSE
, "vmiopg");
1844 * The VFS is telling us this is not a meta-data buffer
1845 * even if it is backed by a block device.
1847 if (bp
->b_flags
& B_NOTMETA
)
1848 vm_page_flag_set(m
, PG_NOTMETA
);
1851 * This is a very important bit of code. We try to track
1852 * VM page use whether the pages are wired into the buffer
1853 * cache or not. While wired into the buffer cache the
1854 * bp tracks the act_count.
1856 * We can choose to place unwired pages on the inactive
1857 * queue (0) or active queue (1). If we place too many
1858 * on the active queue the queue will cycle the act_count
1859 * on pages we'd like to keep, just from single-use pages
1860 * (such as when doing a tar-up or file scan).
1862 if (bp
->b_act_count
< vm_cycle_point
)
1863 vm_page_unwire(m
, 0);
1865 vm_page_unwire(m
, 1);
1868 * If the wire_count has dropped to 0 we may need to take
1869 * further action before unbusying the page.
1871 * WARNING: vm_page_try_*() also checks PG_NEED_COMMIT for us.
1873 if (m
->wire_count
== 0) {
1874 vm_page_flag_clear(m
, PG_ZERO
);
1876 if (bp
->b_flags
& B_DIRECT
) {
1878 * Attempt to free the page if B_DIRECT is
1879 * set, the caller does not desire the page
1883 vm_page_try_to_free(m
);
1884 } else if ((bp
->b_flags
& B_NOTMETA
) ||
1885 vm_page_count_min(0)) {
1887 * Attempt to move the page to PQ_CACHE
1888 * if B_NOTMETA is set. This flag is set
1889 * by HAMMER to remove one of the two pages
1890 * present when double buffering is enabled.
1892 * Attempt to move the page to PQ_CACHE
1893 * If we have a severe page deficit. This
1894 * will cause buffer cache operations related
1895 * to pageouts to recycle the related pages
1896 * in order to avoid a low memory deadlock.
1898 m
->act_count
= bp
->b_act_count
;
1900 vm_page_try_to_cache(m
);
1903 * Nominal case, leave the page on the
1904 * queue the original unwiring placed it on
1905 * (active or inactive).
1907 m
->act_count
= bp
->b_act_count
;
1915 pmap_qremove(trunc_page((vm_offset_t
) bp
->b_data
),
1916 bp
->b_xio
.xio_npages
);
1917 if (bp
->b_bufsize
) {
1921 bp
->b_xio
.xio_npages
= 0;
1922 bp
->b_flags
&= ~B_VMIO
;
1923 KKASSERT (LIST_FIRST(&bp
->b_dep
) == NULL
);
1929 * Find and initialize a new buffer header, freeing up existing buffers
1930 * in the bufqueues as necessary. The new buffer is returned locked.
1932 * Important: B_INVAL is not set. If the caller wishes to throw the
1933 * buffer away, the caller must set B_INVAL prior to calling brelse().
1936 * We have insufficient buffer headers
1937 * We have insufficient buffer space
1938 * buffer_map is too fragmented ( space reservation fails )
1939 * If we have to flush dirty buffers ( but we try to avoid this )
1941 * To avoid VFS layer recursion we do not flush dirty buffers ourselves.
1942 * Instead we ask the buf daemon to do it for us. We attempt to
1943 * avoid piecemeal wakeups of the pageout daemon.
1946 getnewbuf(int blkflags
, int slptimeo
, int size
, int maxsize
)
1948 struct bufpcpu
*pcpu
;
1954 int slpflags
= (blkflags
& GETBLK_PCATCH
) ? PCATCH
: 0;
1955 int maxloops
= 200000;
1956 int restart_reason
= 0;
1957 struct buf
*restart_bp
= NULL
;
1958 static int flushingbufs
;
1961 * We can't afford to block since we might be holding a vnode lock,
1962 * which may prevent system daemons from running. We deal with
1963 * low-memory situations by proactively returning memory and running
1964 * async I/O rather then sync I/O.
1968 --getnewbufrestarts
;
1969 nqcpu
= mycpu
->gd_cpuid
;
1971 ++getnewbufrestarts
;
1973 if (debug_bufbio
&& --maxloops
== 0)
1974 panic("getnewbuf, excessive loops on cpu %d restart %d (%p)",
1975 mycpu
->gd_cpuid
, restart_reason
, restart_bp
);
1978 * Setup for scan. If we do not have enough free buffers,
1979 * we setup a degenerate case that immediately fails. Note
1980 * that if we are specially marked process, we are allowed to
1981 * dip into our reserves.
1983 * The scanning sequence is nominally: EMPTY->EMPTYKVA->CLEAN
1985 * We start with EMPTYKVA. If the list is empty we backup to EMPTY.
1986 * However, there are a number of cases (defragging, reusing, ...)
1987 * where we cannot backup.
1989 pcpu
= &bufpcpu
[nqcpu
];
1990 nqindex
= BQUEUE_EMPTYKVA
;
1991 spin_lock(&pcpu
->spin
);
1993 nbp
= TAILQ_FIRST(&pcpu
->bufqueues
[BQUEUE_EMPTYKVA
]);
1997 * If no EMPTYKVA buffers and we are either
1998 * defragging or reusing, locate a CLEAN buffer
1999 * to free or reuse. If bufspace useage is low
2000 * skip this step so we can allocate a new buffer.
2002 if (defrag
|| bufspace
>= lobufspace
) {
2003 nqindex
= BQUEUE_CLEAN
;
2004 nbp
= TAILQ_FIRST(&pcpu
->bufqueues
[BQUEUE_CLEAN
]);
2008 * If we could not find or were not allowed to reuse a
2009 * CLEAN buffer, check to see if it is ok to use an EMPTY
2010 * buffer. We can only use an EMPTY buffer if allocating
2011 * its KVA would not otherwise run us out of buffer space.
2013 if (nbp
== NULL
&& defrag
== 0 &&
2014 bufspace
+ maxsize
< hibufspace
) {
2015 nqindex
= BQUEUE_EMPTY
;
2016 nbp
= TAILQ_FIRST(&pcpu
->bufqueues
[BQUEUE_EMPTY
]);
2021 * Run scan, possibly freeing data and/or kva mappings on the fly
2024 * WARNING! spin is held!
2026 while ((bp
= nbp
) != NULL
) {
2027 int qindex
= nqindex
;
2029 nbp
= TAILQ_NEXT(bp
, b_freelist
);
2032 * BQUEUE_CLEAN - B_AGE special case. If not set the bp
2033 * cycles through the queue twice before being selected.
2035 if (qindex
== BQUEUE_CLEAN
&&
2036 (bp
->b_flags
& B_AGE
) == 0 && nbp
) {
2037 bp
->b_flags
|= B_AGE
;
2038 TAILQ_REMOVE(&pcpu
->bufqueues
[qindex
],
2040 TAILQ_INSERT_TAIL(&pcpu
->bufqueues
[qindex
],
2046 * Calculate next bp ( we can only use it if we do not block
2047 * or do other fancy things ).
2052 nqindex
= BQUEUE_EMPTYKVA
;
2053 if ((nbp
= TAILQ_FIRST(&pcpu
->bufqueues
[BQUEUE_EMPTYKVA
])))
2056 case BQUEUE_EMPTYKVA
:
2057 nqindex
= BQUEUE_CLEAN
;
2058 if ((nbp
= TAILQ_FIRST(&pcpu
->bufqueues
[BQUEUE_CLEAN
])))
2072 KASSERT(bp
->b_qindex
== qindex
,
2073 ("getnewbuf: inconsistent queue %d bp %p", qindex
, bp
));
2076 * Note: we no longer distinguish between VMIO and non-VMIO
2079 KASSERT((bp
->b_flags
& B_DELWRI
) == 0,
2080 ("delwri buffer %p found in queue %d", bp
, qindex
));
2083 * Do not try to reuse a buffer with a non-zero b_refs.
2084 * This is an unsynchronized test. A synchronized test
2085 * is also performed after we lock the buffer.
2091 * If we are defragging then we need a buffer with
2092 * b_kvasize != 0. XXX this situation should no longer
2093 * occur, if defrag is non-zero the buffer's b_kvasize
2094 * should also be non-zero at this point. XXX
2096 if (defrag
&& bp
->b_kvasize
== 0) {
2097 kprintf("Warning: defrag empty buffer %p\n", bp
);
2102 * Start freeing the bp. This is somewhat involved. nbp
2103 * remains valid only for BQUEUE_EMPTY[KVA] bp's. Buffers
2104 * on the clean list must be disassociated from their
2105 * current vnode. Buffers on the empty[kva] lists have
2106 * already been disassociated.
2108 * b_refs is checked after locking along with queue changes.
2109 * We must check here to deal with zero->nonzero transitions
2110 * made by the owner of the buffer lock, which is used by
2111 * VFS's to hold the buffer while issuing an unlocked
2112 * uiomove()s. We cannot invalidate the buffer's pages
2113 * for this case. Once we successfully lock a buffer the
2114 * only 0->1 transitions of b_refs will occur via findblk().
2116 * We must also check for queue changes after successful
2117 * locking as the current lock holder may dispose of the
2118 * buffer and change its queue.
2120 if (BUF_LOCK(bp
, LK_EXCLUSIVE
| LK_NOWAIT
) != 0) {
2121 spin_unlock(&pcpu
->spin
);
2122 tsleep(&bd_request
, 0, "gnbxxx", (hz
+ 99) / 100);
2127 if (bp
->b_qindex
!= qindex
|| bp
->b_refs
) {
2128 spin_unlock(&pcpu
->spin
);
2134 bremfree_locked(bp
);
2135 spin_unlock(&pcpu
->spin
);
2138 * Dependancies must be handled before we disassociate the
2141 * NOTE: HAMMER will set B_LOCKED if the buffer cannot
2142 * be immediately disassociated. HAMMER then becomes
2143 * responsible for releasing the buffer.
2145 * NOTE: spin is UNLOCKED now.
2147 if (LIST_FIRST(&bp
->b_dep
) != NULL
) {
2149 if (bp
->b_flags
& B_LOCKED
) {
2155 KKASSERT(LIST_FIRST(&bp
->b_dep
) == NULL
);
2158 if (qindex
== BQUEUE_CLEAN
) {
2159 if (bp
->b_flags
& B_VMIO
)
2160 vfs_vmio_release(bp
);
2166 * NOTE: nbp is now entirely invalid. We can only restart
2167 * the scan from this point on.
2169 * Get the rest of the buffer freed up. b_kva* is still
2170 * valid after this operation.
2172 KASSERT(bp
->b_vp
== NULL
,
2173 ("bp3 %p flags %08x vnode %p qindex %d "
2174 "unexpectededly still associated!",
2175 bp
, bp
->b_flags
, bp
->b_vp
, qindex
));
2176 KKASSERT((bp
->b_flags
& B_HASHED
) == 0);
2179 * critical section protection is not required when
2180 * scrapping a buffer's contents because it is already
2186 if (bp
->b_flags
& (B_VNDIRTY
| B_VNCLEAN
| B_HASHED
)) {
2187 kprintf("getnewbuf: caught bug vp queue "
2188 "%p/%08x qidx %d\n",
2189 bp
, bp
->b_flags
, qindex
);
2192 bp
->b_flags
= B_BNOCLIP
;
2193 bp
->b_cmd
= BUF_CMD_DONE
;
2198 bp
->b_xio
.xio_npages
= 0;
2199 bp
->b_dirtyoff
= bp
->b_dirtyend
= 0;
2200 bp
->b_act_count
= ACT_INIT
;
2202 KKASSERT(LIST_FIRST(&bp
->b_dep
) == NULL
);
2204 if (blkflags
& GETBLK_BHEAVY
)
2205 bp
->b_flags
|= B_HEAVY
;
2208 * If we are defragging then free the buffer.
2211 bp
->b_flags
|= B_INVAL
;
2221 * If we are overcomitted then recover the buffer and its
2222 * KVM space. This occurs in rare situations when multiple
2223 * processes are blocked in getnewbuf() or allocbuf().
2225 * On 64-bit systems BKVASIZE == MAXBSIZE and overcommit
2226 * should not be possible.
2228 if (bufspace
>= hibufspace
)
2230 if (BKVASIZE
!= MAXBSIZE
) {
2231 if (flushingbufs
&& bp
->b_kvasize
!= 0) {
2232 bp
->b_flags
|= B_INVAL
;
2240 if (bufspace
< lobufspace
)
2244 * b_refs can transition to a non-zero value while we hold
2245 * the buffer locked due to a findblk(). Our brelvp() above
2246 * interlocked any future possible transitions due to
2249 * If we find b_refs to be non-zero we can destroy the
2250 * buffer's contents but we cannot yet reuse the buffer.
2253 bp
->b_flags
|= B_INVAL
;
2254 if (BKVASIZE
!= MAXBSIZE
)
2262 /* NOT REACHED, spin not held */
2266 * If we exhausted our list, iterate other cpus. If that fails,
2267 * sleep as appropriate. We may have to wakeup various daemons
2268 * and write out some dirty buffers.
2270 * Generally we are sleeping due to insufficient buffer space.
2272 * NOTE: spin is held if bp is NULL, else it is not held.
2278 spin_unlock(&pcpu
->spin
);
2280 nqcpu
= (nqcpu
+ 1) % ncpus
;
2281 if (nqcpu
!= mycpu
->gd_cpuid
) {
2288 flags
= VFS_BIO_NEED_BUFSPACE
;
2290 } else if (bufspace
>= hibufspace
) {
2292 flags
= VFS_BIO_NEED_BUFSPACE
;
2295 flags
= VFS_BIO_NEED_ANY
;
2298 bd_speedup(); /* heeeelp */
2299 atomic_set_int(&needsbuffer
, flags
);
2300 while (needsbuffer
& flags
) {
2303 tsleep_interlock(&needsbuffer
, 0);
2304 value
= atomic_fetchadd_int(&needsbuffer
, 0);
2305 if (value
& flags
) {
2306 if (tsleep(&needsbuffer
, PINTERLOCKED
|slpflags
,
2307 waitmsg
, slptimeo
)) {
2314 * We finally have a valid bp. We aren't quite out of the
2315 * woods, we still have to reserve kva space. In order
2316 * to keep fragmentation sane we only allocate kva in
2319 * (spin is not held)
2321 maxsize
= (maxsize
+ BKVAMASK
) & ~BKVAMASK
;
2323 if (maxsize
!= bp
->b_kvasize
) {
2324 vm_offset_t addr
= 0;
2329 count
= vm_map_entry_reserve(MAP_RESERVE_COUNT
);
2330 vm_map_lock(&buffer_map
);
2332 if (vm_map_findspace(&buffer_map
,
2333 vm_map_min(&buffer_map
), maxsize
,
2334 maxsize
, 0, &addr
)) {
2336 * Uh oh. Buffer map is too fragmented. We
2337 * must defragment the map.
2339 vm_map_unlock(&buffer_map
);
2340 vm_map_entry_release(count
);
2343 bp
->b_flags
|= B_INVAL
;
2350 vm_map_insert(&buffer_map
, &count
,
2352 0, addr
, addr
+ maxsize
,
2354 VM_PROT_ALL
, VM_PROT_ALL
,
2357 bp
->b_kvabase
= (caddr_t
) addr
;
2358 bp
->b_kvasize
= maxsize
;
2359 bufspace
+= bp
->b_kvasize
;
2362 vm_map_unlock(&buffer_map
);
2363 vm_map_entry_release(count
);
2365 bp
->b_data
= bp
->b_kvabase
;
2373 * Buffer flushing daemon. Buffers are normally flushed by the
2374 * update daemon but if it cannot keep up this process starts to
2375 * take the load in an attempt to prevent getnewbuf() from blocking.
2377 * Once a flush is initiated it does not stop until the number
2378 * of buffers falls below lodirtybuffers, but we will wake up anyone
2379 * waiting at the mid-point.
2381 static struct kproc_desc buf_kp
= {
2386 SYSINIT(bufdaemon
, SI_SUB_KTHREAD_BUF
, SI_ORDER_FIRST
,
2387 kproc_start
, &buf_kp
);
2389 static struct kproc_desc bufhw_kp
= {
2394 SYSINIT(bufdaemon_hw
, SI_SUB_KTHREAD_BUF
, SI_ORDER_FIRST
,
2395 kproc_start
, &bufhw_kp
);
2398 buf_daemon1(struct thread
*td
, int queue
, int (*buf_limit_fn
)(long),
2404 marker
= kmalloc(sizeof(*marker
), M_BIOBUF
, M_WAITOK
| M_ZERO
);
2405 marker
->b_flags
|= B_MARKER
;
2406 marker
->b_qindex
= BQUEUE_NONE
;
2410 * This process needs to be suspended prior to shutdown sync.
2412 EVENTHANDLER_REGISTER(shutdown_pre_sync
, shutdown_kproc
,
2413 td
, SHUTDOWN_PRI_LAST
);
2414 curthread
->td_flags
|= TDF_SYSTHREAD
;
2417 * This process is allowed to take the buffer cache to the limit
2420 kproc_suspend_loop();
2423 * Do the flush as long as the number of dirty buffers
2424 * (including those running) exceeds lodirtybufspace.
2426 * When flushing limit running I/O to hirunningspace
2427 * Do the flush. Limit the amount of in-transit I/O we
2428 * allow to build up, otherwise we would completely saturate
2429 * the I/O system. Wakeup any waiting processes before we
2430 * normally would so they can run in parallel with our drain.
2432 * Our aggregate normal+HW lo water mark is lodirtybufspace,
2433 * but because we split the operation into two threads we
2434 * have to cut it in half for each thread.
2436 waitrunningbufspace();
2437 limit
= lodirtybufspace
/ 2;
2438 while (buf_limit_fn(limit
)) {
2439 if (flushbufqueues(marker
, queue
) == 0)
2441 if (runningbufspace
< hirunningspace
)
2443 waitrunningbufspace();
2447 * We reached our low water mark, reset the
2448 * request and sleep until we are needed again.
2449 * The sleep is just so the suspend code works.
2451 tsleep_interlock(bd_req
, 0);
2452 if (atomic_swap_int(bd_req
, 0) == 0)
2453 tsleep(bd_req
, PINTERLOCKED
, "psleep", hz
);
2456 /*kfree(marker, M_BIOBUF);*/
2460 buf_daemon_limit(long limit
)
2462 return (runningbufspace
+ dirtykvaspace
> limit
||
2463 dirtybufcount
- dirtybufcounthw
>= nbuf
/ 2);
2467 buf_daemon_hw_limit(long limit
)
2469 return (runningbufspace
+ dirtykvaspace
> limit
||
2470 dirtybufcounthw
>= nbuf
/ 2);
2476 buf_daemon1(bufdaemon_td
, BQUEUE_DIRTY
, buf_daemon_limit
,
2483 buf_daemon1(bufdaemonhw_td
, BQUEUE_DIRTY_HW
, buf_daemon_hw_limit
,
2488 * Flush up to (flushperqueue) buffers in the dirty queue. Each cpu has a
2489 * localized version of the queue. Each call made to this function iterates
2490 * to another cpu. It is desireable to flush several buffers from the same
2491 * cpu's queue at once, as these are likely going to be linear.
2493 * We must be careful to free up B_INVAL buffers instead of write them, which
2494 * NFS is particularly sensitive to.
2496 * B_RELBUF may only be set by VFSs. We do set B_AGE to indicate that we
2497 * really want to try to get the buffer out and reuse it due to the write
2498 * load on the machine.
2500 * We must lock the buffer in order to check its validity before we can mess
2501 * with its contents. spin isn't enough.
2504 flushbufqueues(struct buf
*marker
, bufq_type_t q
)
2506 struct bufpcpu
*pcpu
;
2509 u_int loops
= flushperqueue
;
2510 int lcpu
= marker
->b_qcpu
;
2512 KKASSERT(marker
->b_qindex
== BQUEUE_NONE
);
2513 KKASSERT(marker
->b_flags
& B_MARKER
);
2517 * Spinlock needed to perform operations on the queue and may be
2518 * held through a non-blocking BUF_LOCK(), but cannot be held when
2519 * BUF_UNLOCK()ing or through any other major operation.
2521 pcpu
= &bufpcpu
[marker
->b_qcpu
];
2522 spin_lock(&pcpu
->spin
);
2523 marker
->b_qindex
= q
;
2524 TAILQ_INSERT_HEAD(&pcpu
->bufqueues
[q
], marker
, b_freelist
);
2527 while ((bp
= TAILQ_NEXT(bp
, b_freelist
)) != NULL
) {
2529 * NOTE: spinlock is always held at the top of the loop
2531 if (bp
->b_flags
& B_MARKER
)
2533 if ((bp
->b_flags
& B_DELWRI
) == 0) {
2534 kprintf("Unexpected clean buffer %p\n", bp
);
2537 if (BUF_LOCK(bp
, LK_EXCLUSIVE
| LK_NOWAIT
))
2539 KKASSERT(bp
->b_qcpu
== marker
->b_qcpu
&& bp
->b_qindex
== q
);
2542 * Once the buffer is locked we will have no choice but to
2543 * unlock the spinlock around a later BUF_UNLOCK and re-set
2544 * bp = marker when looping. Move the marker now to make
2547 TAILQ_REMOVE(&pcpu
->bufqueues
[q
], marker
, b_freelist
);
2548 TAILQ_INSERT_AFTER(&pcpu
->bufqueues
[q
], bp
, marker
, b_freelist
);
2551 * Must recheck B_DELWRI after successfully locking
2554 if ((bp
->b_flags
& B_DELWRI
) == 0) {
2555 spin_unlock(&pcpu
->spin
);
2557 spin_lock(&pcpu
->spin
);
2563 * Remove the buffer from its queue. We still own the
2569 * Disposing of an invalid buffer counts as a flush op
2571 if (bp
->b_flags
& B_INVAL
) {
2572 spin_unlock(&pcpu
->spin
);
2578 * Release the spinlock for the more complex ops we
2579 * are now going to do.
2581 spin_unlock(&pcpu
->spin
);
2585 * This is a bit messy
2587 if (LIST_FIRST(&bp
->b_dep
) != NULL
&&
2588 (bp
->b_flags
& B_DEFERRED
) == 0 &&
2589 buf_countdeps(bp
, 0)) {
2590 spin_lock(&pcpu
->spin
);
2591 TAILQ_INSERT_TAIL(&pcpu
->bufqueues
[q
], bp
, b_freelist
);
2593 bp
->b_flags
|= B_DEFERRED
;
2594 spin_unlock(&pcpu
->spin
);
2596 spin_lock(&pcpu
->spin
);
2602 * spinlock not held here.
2604 * If the buffer has a dependancy, buf_checkwrite() must
2605 * also return 0 for us to be able to initate the write.
2607 * If the buffer is flagged B_ERROR it may be requeued
2608 * over and over again, we try to avoid a live lock.
2610 if (LIST_FIRST(&bp
->b_dep
) != NULL
&& buf_checkwrite(bp
)) {
2612 } else if (bp
->b_flags
& B_ERROR
) {
2613 tsleep(bp
, 0, "bioer", 1);
2614 bp
->b_flags
&= ~B_AGE
;
2617 bp
->b_flags
|= B_AGE
;
2620 /* bp invalid but needs to be NULL-tested if we break out */
2622 spin_lock(&pcpu
->spin
);
2628 /* bp is invalid here but can be NULL-tested to advance */
2630 TAILQ_REMOVE(&pcpu
->bufqueues
[q
], marker
, b_freelist
);
2631 marker
->b_qindex
= BQUEUE_NONE
;
2632 spin_unlock(&pcpu
->spin
);
2635 * Advance the marker to be fair.
2637 marker
->b_qcpu
= (marker
->b_qcpu
+ 1) % ncpus
;
2639 if (marker
->b_qcpu
!= lcpu
)
2649 * Returns true if no I/O is needed to access the associated VM object.
2650 * This is like findblk except it also hunts around in the VM system for
2653 * Note that we ignore vm_page_free() races from interrupts against our
2654 * lookup, since if the caller is not protected our return value will not
2655 * be any more valid then otherwise once we exit the critical section.
2658 inmem(struct vnode
*vp
, off_t loffset
)
2661 vm_offset_t toff
, tinc
, size
;
2665 if (findblk(vp
, loffset
, FINDBLK_TEST
))
2667 if (vp
->v_mount
== NULL
)
2669 if ((obj
= vp
->v_object
) == NULL
)
2673 if (size
> vp
->v_mount
->mnt_stat
.f_iosize
)
2674 size
= vp
->v_mount
->mnt_stat
.f_iosize
;
2676 vm_object_hold(obj
);
2677 for (toff
= 0; toff
< vp
->v_mount
->mnt_stat
.f_iosize
; toff
+= tinc
) {
2678 m
= vm_page_lookup(obj
, OFF_TO_IDX(loffset
+ toff
));
2684 if (tinc
> PAGE_SIZE
- ((toff
+ loffset
) & PAGE_MASK
))
2685 tinc
= PAGE_SIZE
- ((toff
+ loffset
) & PAGE_MASK
);
2686 if (vm_page_is_valid(m
,
2687 (vm_offset_t
) ((toff
+ loffset
) & PAGE_MASK
), tinc
) == 0) {
2692 vm_object_drop(obj
);
2699 * Locate and return the specified buffer. Unless flagged otherwise,
2700 * a locked buffer will be returned if it exists or NULL if it does not.
2702 * findblk()'d buffers are still on the bufqueues and if you intend
2703 * to use your (locked NON-TEST) buffer you need to bremfree(bp)
2704 * and possibly do other stuff to it.
2706 * FINDBLK_TEST - Do not lock the buffer. The caller is responsible
2707 * for locking the buffer and ensuring that it remains
2708 * the desired buffer after locking.
2710 * FINDBLK_NBLOCK - Lock the buffer non-blocking. If we are unable
2711 * to acquire the lock we return NULL, even if the
2714 * FINDBLK_REF - Returns the buffer ref'd, which prevents normal
2715 * reuse by getnewbuf() but does not prevent
2716 * disassociation (B_INVAL). Used to avoid deadlocks
2717 * against random (vp,loffset)s due to reassignment.
2719 * (0) - Lock the buffer blocking.
2722 findblk(struct vnode
*vp
, off_t loffset
, int flags
)
2727 lkflags
= LK_EXCLUSIVE
;
2728 if (flags
& FINDBLK_NBLOCK
)
2729 lkflags
|= LK_NOWAIT
;
2733 * Lookup. Ref the buf while holding v_token to prevent
2734 * reuse (but does not prevent diassociation).
2736 lwkt_gettoken_shared(&vp
->v_token
);
2737 bp
= buf_rb_hash_RB_LOOKUP(&vp
->v_rbhash_tree
, loffset
);
2739 lwkt_reltoken(&vp
->v_token
);
2743 lwkt_reltoken(&vp
->v_token
);
2746 * If testing only break and return bp, do not lock.
2748 if (flags
& FINDBLK_TEST
)
2752 * Lock the buffer, return an error if the lock fails.
2753 * (only FINDBLK_NBLOCK can cause the lock to fail).
2755 if (BUF_LOCK(bp
, lkflags
)) {
2756 atomic_subtract_int(&bp
->b_refs
, 1);
2757 /* bp = NULL; not needed */
2762 * Revalidate the locked buf before allowing it to be
2765 if (bp
->b_vp
== vp
&& bp
->b_loffset
== loffset
)
2767 atomic_subtract_int(&bp
->b_refs
, 1);
2774 if ((flags
& FINDBLK_REF
) == 0)
2775 atomic_subtract_int(&bp
->b_refs
, 1);
2782 * Similar to getblk() except only returns the buffer if it is
2783 * B_CACHE and requires no other manipulation. Otherwise NULL
2784 * is returned. NULL is also returned if GETBLK_NOWAIT is set
2785 * and the getblk() would block.
2787 * If B_RAM is set the buffer might be just fine, but we return
2788 * NULL anyway because we want the code to fall through to the
2789 * cluster read to issue more read-aheads. Otherwise read-ahead breaks.
2791 * If blksize is 0 the buffer cache buffer must already be fully
2794 * If blksize is non-zero getblk() will be used, allowing a buffer
2795 * to be reinstantiated from its VM backing store. The buffer must
2796 * still be fully cached after reinstantiation to be returned.
2799 getcacheblk(struct vnode
*vp
, off_t loffset
, int blksize
, int blkflags
)
2802 int fndflags
= (blkflags
& GETBLK_NOWAIT
) ? FINDBLK_NBLOCK
: 0;
2805 bp
= getblk(vp
, loffset
, blksize
, blkflags
, 0);
2807 if ((bp
->b_flags
& (B_INVAL
| B_CACHE
)) == B_CACHE
) {
2808 bp
->b_flags
&= ~B_AGE
;
2809 if (bp
->b_flags
& B_RAM
) {
2819 bp
= findblk(vp
, loffset
, fndflags
);
2821 if ((bp
->b_flags
& (B_INVAL
| B_CACHE
| B_RAM
)) ==
2823 bp
->b_flags
&= ~B_AGE
;
2837 * Get a block given a specified block and offset into a file/device.
2838 * B_INVAL may or may not be set on return. The caller should clear
2839 * B_INVAL prior to initiating a READ.
2841 * IT IS IMPORTANT TO UNDERSTAND THAT IF YOU CALL GETBLK() AND B_CACHE
2842 * IS NOT SET, YOU MUST INITIALIZE THE RETURNED BUFFER, ISSUE A READ,
2843 * OR SET B_INVAL BEFORE RETIRING IT. If you retire a getblk'd buffer
2844 * without doing any of those things the system will likely believe
2845 * the buffer to be valid (especially if it is not B_VMIO), and the
2846 * next getblk() will return the buffer with B_CACHE set.
2848 * For a non-VMIO buffer, B_CACHE is set to the opposite of B_INVAL for
2849 * an existing buffer.
2851 * For a VMIO buffer, B_CACHE is modified according to the backing VM.
2852 * If getblk()ing a previously 0-sized invalid buffer, B_CACHE is set
2853 * and then cleared based on the backing VM. If the previous buffer is
2854 * non-0-sized but invalid, B_CACHE will be cleared.
2856 * If getblk() must create a new buffer, the new buffer is returned with
2857 * both B_INVAL and B_CACHE clear unless it is a VMIO buffer, in which
2858 * case it is returned with B_INVAL clear and B_CACHE set based on the
2861 * getblk() also forces a bwrite() for any B_DELWRI buffer whos
2862 * B_CACHE bit is clear.
2864 * What this means, basically, is that the caller should use B_CACHE to
2865 * determine whether the buffer is fully valid or not and should clear
2866 * B_INVAL prior to issuing a read. If the caller intends to validate
2867 * the buffer by loading its data area with something, the caller needs
2868 * to clear B_INVAL. If the caller does this without issuing an I/O,
2869 * the caller should set B_CACHE ( as an optimization ), else the caller
2870 * should issue the I/O and biodone() will set B_CACHE if the I/O was
2871 * a write attempt or if it was a successfull read. If the caller
2872 * intends to issue a READ, the caller must clear B_INVAL and B_ERROR
2873 * prior to issuing the READ. biodone() will *not* clear B_INVAL.
2877 * GETBLK_PCATCH - catch signal if blocked, can cause NULL return
2878 * GETBLK_BHEAVY - heavy-weight buffer cache buffer
2881 getblk(struct vnode
*vp
, off_t loffset
, int size
, int blkflags
, int slptimeo
)
2884 int slpflags
= (blkflags
& GETBLK_PCATCH
) ? PCATCH
: 0;
2888 if (size
> MAXBSIZE
)
2889 panic("getblk: size(%d) > MAXBSIZE(%d)", size
, MAXBSIZE
);
2890 if (vp
->v_object
== NULL
)
2891 panic("getblk: vnode %p has no object!", vp
);
2894 if ((bp
= findblk(vp
, loffset
, FINDBLK_REF
| FINDBLK_TEST
)) != NULL
) {
2896 * The buffer was found in the cache, but we need to lock it.
2897 * We must acquire a ref on the bp to prevent reuse, but
2898 * this will not prevent disassociation (brelvp()) so we
2899 * must recheck (vp,loffset) after acquiring the lock.
2901 * Without the ref the buffer could potentially be reused
2902 * before we acquire the lock and create a deadlock
2903 * situation between the thread trying to reuse the buffer
2904 * and us due to the fact that we would wind up blocking
2905 * on a random (vp,loffset).
2907 if (BUF_LOCK(bp
, LK_EXCLUSIVE
| LK_NOWAIT
)) {
2908 if (blkflags
& GETBLK_NOWAIT
) {
2912 lkflags
= LK_EXCLUSIVE
| LK_SLEEPFAIL
;
2913 if (blkflags
& GETBLK_PCATCH
)
2914 lkflags
|= LK_PCATCH
;
2915 error
= BUF_TIMELOCK(bp
, lkflags
, "getblk", slptimeo
);
2918 if (error
== ENOLCK
)
2922 /* buffer may have changed on us */
2927 * Once the buffer has been locked, make sure we didn't race
2928 * a buffer recyclement. Buffers that are no longer hashed
2929 * will have b_vp == NULL, so this takes care of that check
2932 if (bp
->b_vp
!= vp
|| bp
->b_loffset
!= loffset
) {
2934 kprintf("Warning buffer %p (vp %p loffset %lld) "
2936 bp
, vp
, (long long)loffset
);
2943 * If SZMATCH any pre-existing buffer must be of the requested
2944 * size or NULL is returned. The caller absolutely does not
2945 * want getblk() to bwrite() the buffer on a size mismatch.
2947 if ((blkflags
& GETBLK_SZMATCH
) && size
!= bp
->b_bcount
) {
2953 * All vnode-based buffers must be backed by a VM object.
2955 KKASSERT(bp
->b_flags
& B_VMIO
);
2956 KKASSERT(bp
->b_cmd
== BUF_CMD_DONE
);
2957 bp
->b_flags
&= ~B_AGE
;
2960 * Make sure that B_INVAL buffers do not have a cached
2961 * block number translation.
2963 if ((bp
->b_flags
& B_INVAL
) && (bp
->b_bio2
.bio_offset
!= NOOFFSET
)) {
2964 kprintf("Warning invalid buffer %p (vp %p loffset %lld)"
2965 " did not have cleared bio_offset cache\n",
2966 bp
, vp
, (long long)loffset
);
2967 clearbiocache(&bp
->b_bio2
);
2971 * The buffer is locked. B_CACHE is cleared if the buffer is
2974 if (bp
->b_flags
& B_INVAL
)
2975 bp
->b_flags
&= ~B_CACHE
;
2979 * Any size inconsistancy with a dirty buffer or a buffer
2980 * with a softupdates dependancy must be resolved. Resizing
2981 * the buffer in such circumstances can lead to problems.
2983 * Dirty or dependant buffers are written synchronously.
2984 * Other types of buffers are simply released and
2985 * reconstituted as they may be backed by valid, dirty VM
2986 * pages (but not marked B_DELWRI).
2988 * NFS NOTE: NFS buffers which straddle EOF are oddly-sized
2989 * and may be left over from a prior truncation (and thus
2990 * no longer represent the actual EOF point), so we
2991 * definitely do not want to B_NOCACHE the backing store.
2993 if (size
!= bp
->b_bcount
) {
2994 if (bp
->b_flags
& B_DELWRI
) {
2995 bp
->b_flags
|= B_RELBUF
;
2997 } else if (LIST_FIRST(&bp
->b_dep
)) {
2998 bp
->b_flags
|= B_RELBUF
;
3001 bp
->b_flags
|= B_RELBUF
;
3006 KKASSERT(size
<= bp
->b_kvasize
);
3007 KASSERT(bp
->b_loffset
!= NOOFFSET
,
3008 ("getblk: no buffer offset"));
3011 * A buffer with B_DELWRI set and B_CACHE clear must
3012 * be committed before we can return the buffer in
3013 * order to prevent the caller from issuing a read
3014 * ( due to B_CACHE not being set ) and overwriting
3017 * Most callers, including NFS and FFS, need this to
3018 * operate properly either because they assume they
3019 * can issue a read if B_CACHE is not set, or because
3020 * ( for example ) an uncached B_DELWRI might loop due
3021 * to softupdates re-dirtying the buffer. In the latter
3022 * case, B_CACHE is set after the first write completes,
3023 * preventing further loops.
3025 * NOTE! b*write() sets B_CACHE. If we cleared B_CACHE
3026 * above while extending the buffer, we cannot allow the
3027 * buffer to remain with B_CACHE set after the write
3028 * completes or it will represent a corrupt state. To
3029 * deal with this we set B_NOCACHE to scrap the buffer
3032 * XXX Should this be B_RELBUF instead of B_NOCACHE?
3033 * I'm not even sure this state is still possible
3034 * now that getblk() writes out any dirty buffers
3037 * We might be able to do something fancy, like setting
3038 * B_CACHE in bwrite() except if B_DELWRI is already set,
3039 * so the below call doesn't set B_CACHE, but that gets real
3040 * confusing. This is much easier.
3043 if ((bp
->b_flags
& (B_CACHE
|B_DELWRI
)) == B_DELWRI
) {
3044 kprintf("getblk: Warning, bp %p loff=%jx DELWRI set "
3045 "and CACHE clear, b_flags %08x\n",
3046 bp
, (uintmax_t)bp
->b_loffset
, bp
->b_flags
);
3047 bp
->b_flags
|= B_NOCACHE
;
3053 * Buffer is not in-core, create new buffer. The buffer
3054 * returned by getnewbuf() is locked. Note that the returned
3055 * buffer is also considered valid (not marked B_INVAL).
3057 * Calculating the offset for the I/O requires figuring out
3058 * the block size. We use DEV_BSIZE for VBLK or VCHR and
3059 * the mount's f_iosize otherwise. If the vnode does not
3060 * have an associated mount we assume that the passed size is
3063 * Note that vn_isdisk() cannot be used here since it may
3064 * return a failure for numerous reasons. Note that the
3065 * buffer size may be larger then the block size (the caller
3066 * will use block numbers with the proper multiple). Beware
3067 * of using any v_* fields which are part of unions. In
3068 * particular, in DragonFly the mount point overloading
3069 * mechanism uses the namecache only and the underlying
3070 * directory vnode is not a special case.
3074 if (vp
->v_type
== VBLK
|| vp
->v_type
== VCHR
)
3076 else if (vp
->v_mount
)
3077 bsize
= vp
->v_mount
->mnt_stat
.f_iosize
;
3081 maxsize
= size
+ (loffset
& PAGE_MASK
);
3082 maxsize
= imax(maxsize
, bsize
);
3084 bp
= getnewbuf(blkflags
, slptimeo
, size
, maxsize
);
3086 if (slpflags
|| slptimeo
)
3092 * Atomically insert the buffer into the hash, so that it can
3093 * be found by findblk().
3095 * If bgetvp() returns non-zero a collision occured, and the
3096 * bp will not be associated with the vnode.
3098 * Make sure the translation layer has been cleared.
3100 bp
->b_loffset
= loffset
;
3101 bp
->b_bio2
.bio_offset
= NOOFFSET
;
3102 /* bp->b_bio2.bio_next = NULL; */
3104 if (bgetvp(vp
, bp
, size
)) {
3105 bp
->b_flags
|= B_INVAL
;
3111 * All vnode-based buffers must be backed by a VM object.
3113 KKASSERT(vp
->v_object
!= NULL
);
3114 bp
->b_flags
|= B_VMIO
;
3115 KKASSERT(bp
->b_cmd
== BUF_CMD_DONE
);
3125 * Reacquire a buffer that was previously released to the locked queue,
3126 * or reacquire a buffer which is interlocked by having bioops->io_deallocate
3127 * set B_LOCKED (which handles the acquisition race).
3129 * To this end, either B_LOCKED must be set or the dependancy list must be
3133 regetblk(struct buf
*bp
)
3135 KKASSERT((bp
->b_flags
& B_LOCKED
) || LIST_FIRST(&bp
->b_dep
) != NULL
);
3136 BUF_LOCK(bp
, LK_EXCLUSIVE
| LK_RETRY
);
3143 * Get an empty, disassociated buffer of given size. The buffer is
3144 * initially set to B_INVAL.
3146 * critical section protection is not required for the allocbuf()
3147 * call because races are impossible here.
3155 maxsize
= (size
+ BKVAMASK
) & ~BKVAMASK
;
3157 while ((bp
= getnewbuf(0, 0, size
, maxsize
)) == NULL
)
3160 bp
->b_flags
|= B_INVAL
; /* b_dep cleared by getnewbuf() */
3168 * This code constitutes the buffer memory from either anonymous system
3169 * memory (in the case of non-VMIO operations) or from an associated
3170 * VM object (in the case of VMIO operations). This code is able to
3171 * resize a buffer up or down.
3173 * Note that this code is tricky, and has many complications to resolve
3174 * deadlock or inconsistant data situations. Tread lightly!!!
3175 * There are B_CACHE and B_DELWRI interactions that must be dealt with by
3176 * the caller. Calling this code willy nilly can result in the loss of
3179 * allocbuf() only adjusts B_CACHE for VMIO buffers. getblk() deals with
3180 * B_CACHE for the non-VMIO case.
3182 * This routine does not need to be called from a critical section but you
3183 * must own the buffer.
3186 allocbuf(struct buf
*bp
, int size
)
3188 int newbsize
, mbsize
;
3191 if (BUF_REFCNT(bp
) == 0)
3192 panic("allocbuf: buffer not busy");
3194 if (bp
->b_kvasize
< size
)
3195 panic("allocbuf: buffer too small");
3197 if ((bp
->b_flags
& B_VMIO
) == 0) {
3201 * Just get anonymous memory from the kernel. Don't
3202 * mess with B_CACHE.
3204 mbsize
= roundup2(size
, DEV_BSIZE
);
3205 if (bp
->b_flags
& B_MALLOC
)
3208 newbsize
= round_page(size
);
3210 if (newbsize
< bp
->b_bufsize
) {
3212 * Malloced buffers are not shrunk
3214 if (bp
->b_flags
& B_MALLOC
) {
3216 bp
->b_bcount
= size
;
3218 kfree(bp
->b_data
, M_BIOBUF
);
3219 if (bp
->b_bufsize
) {
3220 atomic_subtract_long(&bufmallocspace
, bp
->b_bufsize
);
3224 bp
->b_data
= bp
->b_kvabase
;
3226 bp
->b_flags
&= ~B_MALLOC
;
3232 (vm_offset_t
) bp
->b_data
+ newbsize
,
3233 (vm_offset_t
) bp
->b_data
+ bp
->b_bufsize
);
3234 } else if (newbsize
> bp
->b_bufsize
) {
3236 * We only use malloced memory on the first allocation.
3237 * and revert to page-allocated memory when the buffer
3240 if ((bufmallocspace
< maxbufmallocspace
) &&
3241 (bp
->b_bufsize
== 0) &&
3242 (mbsize
<= PAGE_SIZE
/2)) {
3244 bp
->b_data
= kmalloc(mbsize
, M_BIOBUF
, M_WAITOK
);
3245 bp
->b_bufsize
= mbsize
;
3246 bp
->b_bcount
= size
;
3247 bp
->b_flags
|= B_MALLOC
;
3248 atomic_add_long(&bufmallocspace
, mbsize
);
3254 * If the buffer is growing on its other-than-first
3255 * allocation, then we revert to the page-allocation
3258 if (bp
->b_flags
& B_MALLOC
) {
3259 origbuf
= bp
->b_data
;
3260 origbufsize
= bp
->b_bufsize
;
3261 bp
->b_data
= bp
->b_kvabase
;
3262 if (bp
->b_bufsize
) {
3263 atomic_subtract_long(&bufmallocspace
,
3268 bp
->b_flags
&= ~B_MALLOC
;
3269 newbsize
= round_page(newbsize
);
3273 (vm_offset_t
) bp
->b_data
+ bp
->b_bufsize
,
3274 (vm_offset_t
) bp
->b_data
+ newbsize
);
3276 bcopy(origbuf
, bp
->b_data
, origbufsize
);
3277 kfree(origbuf
, M_BIOBUF
);
3284 newbsize
= roundup2(size
, DEV_BSIZE
);
3285 desiredpages
= ((int)(bp
->b_loffset
& PAGE_MASK
) +
3286 newbsize
+ PAGE_MASK
) >> PAGE_SHIFT
;
3287 KKASSERT(desiredpages
<= XIO_INTERNAL_PAGES
);
3289 if (bp
->b_flags
& B_MALLOC
)
3290 panic("allocbuf: VMIO buffer can't be malloced");
3292 * Set B_CACHE initially if buffer is 0 length or will become
3295 if (size
== 0 || bp
->b_bufsize
== 0)
3296 bp
->b_flags
|= B_CACHE
;
3298 if (newbsize
< bp
->b_bufsize
) {
3300 * DEV_BSIZE aligned new buffer size is less then the
3301 * DEV_BSIZE aligned existing buffer size. Figure out
3302 * if we have to remove any pages.
3304 if (desiredpages
< bp
->b_xio
.xio_npages
) {
3305 for (i
= desiredpages
; i
< bp
->b_xio
.xio_npages
; i
++) {
3307 * the page is not freed here -- it
3308 * is the responsibility of
3309 * vnode_pager_setsize
3311 m
= bp
->b_xio
.xio_pages
[i
];
3312 KASSERT(m
!= bogus_page
,
3313 ("allocbuf: bogus page found"));
3314 vm_page_busy_wait(m
, TRUE
, "biodep");
3315 bp
->b_xio
.xio_pages
[i
] = NULL
;
3316 vm_page_unwire(m
, 0);
3319 pmap_qremove((vm_offset_t
) trunc_page((vm_offset_t
)bp
->b_data
) +
3320 (desiredpages
<< PAGE_SHIFT
), (bp
->b_xio
.xio_npages
- desiredpages
));
3321 bp
->b_xio
.xio_npages
= desiredpages
;
3323 } else if (size
> bp
->b_bcount
) {
3325 * We are growing the buffer, possibly in a
3326 * byte-granular fashion.
3334 * Step 1, bring in the VM pages from the object,
3335 * allocating them if necessary. We must clear
3336 * B_CACHE if these pages are not valid for the
3337 * range covered by the buffer.
3339 * critical section protection is required to protect
3340 * against interrupts unbusying and freeing pages
3341 * between our vm_page_lookup() and our
3342 * busycheck/wiring call.
3347 vm_object_hold(obj
);
3348 while (bp
->b_xio
.xio_npages
< desiredpages
) {
3353 pi
= OFF_TO_IDX(bp
->b_loffset
) +
3354 bp
->b_xio
.xio_npages
;
3357 * Blocking on m->busy might lead to a
3360 * vm_fault->getpages->cluster_read->allocbuf
3362 m
= vm_page_lookup_busy_try(obj
, pi
, FALSE
,
3365 vm_page_sleep_busy(m
, FALSE
, "pgtblk");
3370 * note: must allocate system pages
3371 * since blocking here could intefere
3372 * with paging I/O, no matter which
3375 m
= bio_page_alloc(bp
, obj
, pi
, desiredpages
- bp
->b_xio
.xio_npages
);
3378 vm_page_flag_clear(m
, PG_ZERO
);
3380 bp
->b_flags
&= ~B_CACHE
;
3381 bp
->b_xio
.xio_pages
[bp
->b_xio
.xio_npages
] = m
;
3382 ++bp
->b_xio
.xio_npages
;
3388 * We found a page and were able to busy it.
3390 vm_page_flag_clear(m
, PG_ZERO
);
3393 bp
->b_xio
.xio_pages
[bp
->b_xio
.xio_npages
] = m
;
3394 ++bp
->b_xio
.xio_npages
;
3395 if (bp
->b_act_count
< m
->act_count
)
3396 bp
->b_act_count
= m
->act_count
;
3398 vm_object_drop(obj
);
3401 * Step 2. We've loaded the pages into the buffer,
3402 * we have to figure out if we can still have B_CACHE
3403 * set. Note that B_CACHE is set according to the
3404 * byte-granular range ( bcount and size ), not the
3405 * aligned range ( newbsize ).
3407 * The VM test is against m->valid, which is DEV_BSIZE
3408 * aligned. Needless to say, the validity of the data
3409 * needs to also be DEV_BSIZE aligned. Note that this
3410 * fails with NFS if the server or some other client
3411 * extends the file's EOF. If our buffer is resized,
3412 * B_CACHE may remain set! XXX
3415 toff
= bp
->b_bcount
;
3416 tinc
= PAGE_SIZE
- ((bp
->b_loffset
+ toff
) & PAGE_MASK
);
3418 while ((bp
->b_flags
& B_CACHE
) && toff
< size
) {
3421 if (tinc
> (size
- toff
))
3424 pi
= ((bp
->b_loffset
& PAGE_MASK
) + toff
) >>
3432 bp
->b_xio
.xio_pages
[pi
]
3439 * Step 3, fixup the KVM pmap. Remember that
3440 * bp->b_data is relative to bp->b_loffset, but
3441 * bp->b_loffset may be offset into the first page.
3444 bp
->b_data
= (caddr_t
)
3445 trunc_page((vm_offset_t
)bp
->b_data
);
3447 (vm_offset_t
)bp
->b_data
,
3448 bp
->b_xio
.xio_pages
,
3449 bp
->b_xio
.xio_npages
3451 bp
->b_data
= (caddr_t
)((vm_offset_t
)bp
->b_data
|
3452 (vm_offset_t
)(bp
->b_loffset
& PAGE_MASK
));
3456 /* adjust space use on already-dirty buffer */
3457 if (bp
->b_flags
& B_DELWRI
) {
3458 /* dirtykvaspace unchanged */
3459 atomic_add_long(&dirtybufspace
, newbsize
- bp
->b_bufsize
);
3460 if (bp
->b_flags
& B_HEAVY
) {
3461 atomic_add_long(&dirtybufspacehw
,
3462 newbsize
- bp
->b_bufsize
);
3465 if (newbsize
< bp
->b_bufsize
)
3467 bp
->b_bufsize
= newbsize
; /* actual buffer allocation */
3468 bp
->b_bcount
= size
; /* requested buffer size */
3475 * Wait for buffer I/O completion, returning error status. B_EINTR
3476 * is converted into an EINTR error but not cleared (since a chain
3477 * of biowait() calls may occur).
3479 * On return bpdone() will have been called but the buffer will remain
3480 * locked and will not have been brelse()'d.
3482 * NOTE! If a timeout is specified and ETIMEDOUT occurs the I/O is
3483 * likely still in progress on return.
3485 * NOTE! This operation is on a BIO, not a BUF.
3487 * NOTE! BIO_DONE is cleared by vn_strategy()
3490 _biowait(struct bio
*bio
, const char *wmesg
, int to
)
3492 struct buf
*bp
= bio
->bio_buf
;
3497 KKASSERT(bio
== &bp
->b_bio1
);
3499 flags
= bio
->bio_flags
;
3500 if (flags
& BIO_DONE
)
3502 nflags
= flags
| BIO_WANT
;
3503 tsleep_interlock(bio
, 0);
3504 if (atomic_cmpset_int(&bio
->bio_flags
, flags
, nflags
)) {
3506 error
= tsleep(bio
, PINTERLOCKED
, wmesg
, to
);
3507 else if (bp
->b_cmd
== BUF_CMD_READ
)
3508 error
= tsleep(bio
, PINTERLOCKED
, "biord", to
);
3510 error
= tsleep(bio
, PINTERLOCKED
, "biowr", to
);
3512 kprintf("tsleep error biowait %d\n", error
);
3521 KKASSERT(bp
->b_cmd
== BUF_CMD_DONE
);
3522 bio
->bio_flags
&= ~(BIO_DONE
| BIO_SYNC
);
3523 if (bp
->b_flags
& B_EINTR
)
3525 if (bp
->b_flags
& B_ERROR
)
3526 return (bp
->b_error
? bp
->b_error
: EIO
);
3531 biowait(struct bio
*bio
, const char *wmesg
)
3533 return(_biowait(bio
, wmesg
, 0));
3537 biowait_timeout(struct bio
*bio
, const char *wmesg
, int to
)
3539 return(_biowait(bio
, wmesg
, to
));
3543 * This associates a tracking count with an I/O. vn_strategy() and
3544 * dev_dstrategy() do this automatically but there are a few cases
3545 * where a vnode or device layer is bypassed when a block translation
3546 * is cached. In such cases bio_start_transaction() may be called on
3547 * the bypassed layers so the system gets an I/O in progress indication
3548 * for those higher layers.
3551 bio_start_transaction(struct bio
*bio
, struct bio_track
*track
)
3553 bio
->bio_track
= track
;
3554 bio_track_ref(track
);
3555 dsched_buf_enter(bio
->bio_buf
); /* might stack */
3559 * Initiate I/O on a vnode.
3561 * SWAPCACHE OPERATION:
3563 * Real buffer cache buffers have a non-NULL bp->b_vp. Unfortunately
3564 * devfs also uses b_vp for fake buffers so we also have to check
3565 * that B_PAGING is 0. In this case the passed 'vp' is probably the
3566 * underlying block device. The swap assignments are related to the
3567 * buffer cache buffer's b_vp, not the passed vp.
3569 * The passed vp == bp->b_vp only in the case where the strategy call
3570 * is made on the vp itself for its own buffers (a regular file or
3571 * block device vp). The filesystem usually then re-calls vn_strategy()
3572 * after translating the request to an underlying device.
3574 * Cluster buffers set B_CLUSTER and the passed vp is the vp of the
3575 * underlying buffer cache buffers.
3577 * We can only deal with page-aligned buffers at the moment, because
3578 * we can't tell what the real dirty state for pages straddling a buffer
3581 * In order to call swap_pager_strategy() we must provide the VM object
3582 * and base offset for the underlying buffer cache pages so it can find
3586 vn_strategy(struct vnode
*vp
, struct bio
*bio
)
3588 struct bio_track
*track
;
3589 struct buf
*bp
= bio
->bio_buf
;
3591 KKASSERT(bp
->b_cmd
!= BUF_CMD_DONE
);
3594 * Set when an I/O is issued on the bp. Cleared by consumers
3595 * (aka HAMMER), allowing the consumer to determine if I/O had
3596 * actually occurred.
3598 bp
->b_flags
|= B_IOISSUED
;
3601 * Handle the swap cache intercept.
3603 if (vn_cache_strategy(vp
, bio
))
3607 * Otherwise do the operation through the filesystem
3609 if (bp
->b_cmd
== BUF_CMD_READ
)
3610 track
= &vp
->v_track_read
;
3612 track
= &vp
->v_track_write
;
3613 KKASSERT((bio
->bio_flags
& BIO_DONE
) == 0);
3614 bio
->bio_track
= track
;
3615 bio_track_ref(track
);
3616 dsched_buf_enter(bp
); /* might stack */
3617 vop_strategy(*vp
->v_ops
, vp
, bio
);
3620 static void vn_cache_strategy_callback(struct bio
*bio
);
3623 vn_cache_strategy(struct vnode
*vp
, struct bio
*bio
)
3625 struct buf
*bp
= bio
->bio_buf
;
3632 * Stop using swapcache if paniced, dumping, or dumped
3634 if (panicstr
|| dumping
)
3638 * Is this buffer cache buffer suitable for reading from
3641 if (vm_swapcache_read_enable
== 0 ||
3642 bp
->b_cmd
!= BUF_CMD_READ
||
3643 ((bp
->b_flags
& B_CLUSTER
) == 0 &&
3644 (bp
->b_vp
== NULL
|| (bp
->b_flags
& B_PAGING
))) ||
3645 ((int)bp
->b_loffset
& PAGE_MASK
) != 0 ||
3646 (bp
->b_bcount
& PAGE_MASK
) != 0) {
3651 * Figure out the original VM object (it will match the underlying
3652 * VM pages). Note that swap cached data uses page indices relative
3653 * to that object, not relative to bio->bio_offset.
3655 if (bp
->b_flags
& B_CLUSTER
)
3656 object
= vp
->v_object
;
3658 object
= bp
->b_vp
->v_object
;
3661 * In order to be able to use the swap cache all underlying VM
3662 * pages must be marked as such, and we can't have any bogus pages.
3664 for (i
= 0; i
< bp
->b_xio
.xio_npages
; ++i
) {
3665 m
= bp
->b_xio
.xio_pages
[i
];
3666 if ((m
->flags
& PG_SWAPPED
) == 0)
3668 if (m
== bogus_page
)
3673 * If we are good then issue the I/O using swap_pager_strategy().
3675 * We can only do this if the buffer actually supports object-backed
3676 * I/O. If it doesn't npages will be 0.
3678 if (i
&& i
== bp
->b_xio
.xio_npages
) {
3679 m
= bp
->b_xio
.xio_pages
[0];
3680 nbio
= push_bio(bio
);
3681 nbio
->bio_done
= vn_cache_strategy_callback
;
3682 nbio
->bio_offset
= ptoa(m
->pindex
);
3683 KKASSERT(m
->object
== object
);
3684 swap_pager_strategy(object
, nbio
);
3691 * This is a bit of a hack but since the vn_cache_strategy() function can
3692 * override a VFS's strategy function we must make sure that the bio, which
3693 * is probably bio2, doesn't leak an unexpected offset value back to the
3694 * filesystem. The filesystem (e.g. UFS) might otherwise assume that the
3695 * bio went through its own file strategy function and the the bio2 offset
3696 * is a cached disk offset when, in fact, it isn't.
3699 vn_cache_strategy_callback(struct bio
*bio
)
3701 bio
->bio_offset
= NOOFFSET
;
3702 biodone(pop_bio(bio
));
3708 * Finish I/O on a buffer after all BIOs have been processed.
3709 * Called when the bio chain is exhausted or by biowait. If called
3710 * by biowait, elseit is typically 0.
3712 * bpdone is also responsible for setting B_CACHE in a B_VMIO bp.
3713 * In a non-VMIO bp, B_CACHE will be set on the next getblk()
3714 * assuming B_INVAL is clear.
3716 * For the VMIO case, we set B_CACHE if the op was a read and no
3717 * read error occured, or if the op was a write. B_CACHE is never
3718 * set if the buffer is invalid or otherwise uncacheable.
3720 * bpdone does not mess with B_INVAL, allowing the I/O routine or the
3721 * initiator to leave B_INVAL set to brelse the buffer out of existance
3722 * in the biodone routine.
3724 * bpdone is responsible for calling bundirty() on the buffer after a
3725 * successful write. We previously did this prior to initiating the
3726 * write under the assumption that the buffer might be dirtied again
3727 * while the write was in progress, however doing it before-hand creates
3728 * a race condition prior to the call to vn_strategy() where the
3729 * filesystem may not be aware that a dirty buffer is present.
3730 * It should not be possible for the buffer or its underlying pages to
3731 * be redirtied prior to bpdone()'s unbusying of the underlying VM
3735 bpdone(struct buf
*bp
, int elseit
)
3739 KASSERT(BUF_REFCNTNB(bp
) > 0,
3740 ("bpdone: bp %p not busy %d", bp
, BUF_REFCNTNB(bp
)));
3741 KASSERT(bp
->b_cmd
!= BUF_CMD_DONE
,
3742 ("bpdone: bp %p already done!", bp
));
3745 * No more BIOs are left. All completion functions have been dealt
3746 * with, now we clean up the buffer.
3749 bp
->b_cmd
= BUF_CMD_DONE
;
3752 * Only reads and writes are processed past this point.
3754 if (cmd
!= BUF_CMD_READ
&& cmd
!= BUF_CMD_WRITE
) {
3755 if (cmd
== BUF_CMD_FREEBLKS
)
3756 bp
->b_flags
|= B_NOCACHE
;
3763 * A failed write must re-dirty the buffer unless B_INVAL
3766 * A successful write must clear the dirty flag. This is done after
3767 * the write to ensure that the buffer remains on the vnode's dirty
3768 * list for filesystem interlocks / checks until the write is actually
3769 * complete. HAMMER2 is sensitive to this issue.
3771 * Only applicable to normal buffers (with VPs). vinum buffers may
3774 * Must be done prior to calling buf_complete() as the callback might
3775 * re-dirty the buffer.
3777 if (cmd
== BUF_CMD_WRITE
) {
3778 if ((bp
->b_flags
& (B_ERROR
| B_INVAL
)) == B_ERROR
) {
3779 bp
->b_flags
&= ~B_NOCACHE
;
3789 * Warning: softupdates may re-dirty the buffer, and HAMMER can do
3790 * a lot worse. XXX - move this above the clearing of b_cmd
3792 if (LIST_FIRST(&bp
->b_dep
) != NULL
)
3795 if (bp
->b_flags
& B_VMIO
) {
3801 struct vnode
*vp
= bp
->b_vp
;
3805 #if defined(VFS_BIO_DEBUG)
3806 if (vp
->v_auxrefs
== 0)
3807 panic("bpdone: zero vnode hold count");
3808 if ((vp
->v_flag
& VOBJBUF
) == 0)
3809 panic("bpdone: vnode is not setup for merged cache");
3812 foff
= bp
->b_loffset
;
3813 KASSERT(foff
!= NOOFFSET
, ("bpdone: no buffer offset"));
3814 KASSERT(obj
!= NULL
, ("bpdone: missing VM object"));
3816 #if defined(VFS_BIO_DEBUG)
3817 if (obj
->paging_in_progress
< bp
->b_xio
.xio_npages
) {
3818 kprintf("bpdone: paging in progress(%d) < "
3819 "bp->b_xio.xio_npages(%d)\n",
3820 obj
->paging_in_progress
,
3821 bp
->b_xio
.xio_npages
);
3826 * Set B_CACHE if the op was a normal read and no error
3827 * occured. B_CACHE is set for writes in the b*write()
3830 iosize
= bp
->b_bcount
- bp
->b_resid
;
3831 if (cmd
== BUF_CMD_READ
&&
3832 (bp
->b_flags
& (B_INVAL
|B_NOCACHE
|B_ERROR
)) == 0) {
3833 bp
->b_flags
|= B_CACHE
;
3836 vm_object_hold(obj
);
3837 for (i
= 0; i
< bp
->b_xio
.xio_npages
; i
++) {
3841 resid
= ((foff
+ PAGE_SIZE
) & ~(off_t
)PAGE_MASK
) - foff
;
3846 * cleanup bogus pages, restoring the originals. Since
3847 * the originals should still be wired, we don't have
3848 * to worry about interrupt/freeing races destroying
3849 * the VM object association.
3851 m
= bp
->b_xio
.xio_pages
[i
];
3852 if (m
== bogus_page
) {
3854 m
= vm_page_lookup(obj
, OFF_TO_IDX(foff
));
3856 panic("bpdone: page disappeared");
3857 bp
->b_xio
.xio_pages
[i
] = m
;
3858 pmap_qenter(trunc_page((vm_offset_t
)bp
->b_data
),
3859 bp
->b_xio
.xio_pages
, bp
->b_xio
.xio_npages
);
3861 #if defined(VFS_BIO_DEBUG)
3862 if (OFF_TO_IDX(foff
) != m
->pindex
) {
3863 kprintf("bpdone: foff(%lu)/m->pindex(%ld) "
3865 (unsigned long)foff
, (long)m
->pindex
);
3870 * In the write case, the valid and clean bits are
3871 * already changed correctly (see bdwrite()), so we
3872 * only need to do this here in the read case.
3874 vm_page_busy_wait(m
, FALSE
, "bpdpgw");
3875 if (cmd
== BUF_CMD_READ
&& !bogusflag
&& resid
> 0) {
3876 vfs_clean_one_page(bp
, i
, m
);
3878 vm_page_flag_clear(m
, PG_ZERO
);
3881 * when debugging new filesystems or buffer I/O
3882 * methods, this is the most common error that pops
3883 * up. if you see this, you have not set the page
3884 * busy flag correctly!!!
3887 kprintf("bpdone: page busy < 0, "
3888 "pindex: %d, foff: 0x(%x,%x), "
3889 "resid: %d, index: %d\n",
3890 (int) m
->pindex
, (int)(foff
>> 32),
3891 (int) foff
& 0xffffffff, resid
, i
);
3892 if (!vn_isdisk(vp
, NULL
))
3893 kprintf(" iosize: %ld, loffset: %lld, "
3894 "flags: 0x%08x, npages: %d\n",
3895 bp
->b_vp
->v_mount
->mnt_stat
.f_iosize
,
3896 (long long)bp
->b_loffset
,
3897 bp
->b_flags
, bp
->b_xio
.xio_npages
);
3899 kprintf(" VDEV, loffset: %lld, flags: 0x%08x, npages: %d\n",
3900 (long long)bp
->b_loffset
,
3901 bp
->b_flags
, bp
->b_xio
.xio_npages
);
3902 kprintf(" valid: 0x%x, dirty: 0x%x, "
3906 panic("bpdone: page busy < 0");
3908 vm_page_io_finish(m
);
3910 vm_object_pip_wakeup(obj
);
3911 foff
= (foff
+ PAGE_SIZE
) & ~(off_t
)PAGE_MASK
;
3914 bp
->b_flags
&= ~B_HASBOGUS
;
3915 vm_object_drop(obj
);
3919 * Finish up by releasing the buffer. There are no more synchronous
3920 * or asynchronous completions, those were handled by bio_done
3924 if (bp
->b_flags
& (B_NOCACHE
|B_INVAL
|B_ERROR
|B_RELBUF
))
3935 biodone(struct bio
*bio
)
3937 struct buf
*bp
= bio
->bio_buf
;
3939 runningbufwakeup(bp
);
3942 * Run up the chain of BIO's. Leave b_cmd intact for the duration.
3945 biodone_t
*done_func
;
3946 struct bio_track
*track
;
3949 * BIO tracking. Most but not all BIOs are tracked.
3951 if ((track
= bio
->bio_track
) != NULL
) {
3952 bio_track_rel(track
);
3953 bio
->bio_track
= NULL
;
3957 * A bio_done function terminates the loop. The function
3958 * will be responsible for any further chaining and/or
3959 * buffer management.
3961 * WARNING! The done function can deallocate the buffer!
3963 if ((done_func
= bio
->bio_done
) != NULL
) {
3964 bio
->bio_done
= NULL
;
3968 bio
= bio
->bio_prev
;
3972 * If we've run out of bio's do normal [a]synchronous completion.
3978 * Synchronous biodone - this terminates a synchronous BIO.
3980 * bpdone() is called with elseit=FALSE, leaving the buffer completed
3981 * but still locked. The caller must brelse() the buffer after waiting
3985 biodone_sync(struct bio
*bio
)
3987 struct buf
*bp
= bio
->bio_buf
;
3991 KKASSERT(bio
== &bp
->b_bio1
);
3995 flags
= bio
->bio_flags
;
3996 nflags
= (flags
| BIO_DONE
) & ~BIO_WANT
;
3998 if (atomic_cmpset_int(&bio
->bio_flags
, flags
, nflags
)) {
3999 if (flags
& BIO_WANT
)
4009 * This routine is called in lieu of iodone in the case of
4010 * incomplete I/O. This keeps the busy status for pages
4014 vfs_unbusy_pages(struct buf
*bp
)
4018 runningbufwakeup(bp
);
4020 if (bp
->b_flags
& B_VMIO
) {
4021 struct vnode
*vp
= bp
->b_vp
;
4025 vm_object_hold(obj
);
4027 for (i
= 0; i
< bp
->b_xio
.xio_npages
; i
++) {
4028 vm_page_t m
= bp
->b_xio
.xio_pages
[i
];
4031 * When restoring bogus changes the original pages
4032 * should still be wired, so we are in no danger of
4033 * losing the object association and do not need
4034 * critical section protection particularly.
4036 if (m
== bogus_page
) {
4037 m
= vm_page_lookup(obj
, OFF_TO_IDX(bp
->b_loffset
) + i
);
4039 panic("vfs_unbusy_pages: page missing");
4041 bp
->b_xio
.xio_pages
[i
] = m
;
4042 pmap_qenter(trunc_page((vm_offset_t
)bp
->b_data
),
4043 bp
->b_xio
.xio_pages
, bp
->b_xio
.xio_npages
);
4045 vm_page_busy_wait(m
, FALSE
, "bpdpgw");
4046 vm_page_flag_clear(m
, PG_ZERO
);
4047 vm_page_io_finish(m
);
4049 vm_object_pip_wakeup(obj
);
4051 bp
->b_flags
&= ~B_HASBOGUS
;
4052 vm_object_drop(obj
);
4059 * This routine is called before a device strategy routine.
4060 * It is used to tell the VM system that paging I/O is in
4061 * progress, and treat the pages associated with the buffer
4062 * almost as being PG_BUSY. Also the object 'paging_in_progress'
4063 * flag is handled to make sure that the object doesn't become
4066 * Since I/O has not been initiated yet, certain buffer flags
4067 * such as B_ERROR or B_INVAL may be in an inconsistant state
4068 * and should be ignored.
4071 vfs_busy_pages(struct vnode
*vp
, struct buf
*bp
)
4074 struct lwp
*lp
= curthread
->td_lwp
;
4077 * The buffer's I/O command must already be set. If reading,
4078 * B_CACHE must be 0 (double check against callers only doing
4079 * I/O when B_CACHE is 0).
4081 KKASSERT(bp
->b_cmd
!= BUF_CMD_DONE
);
4082 KKASSERT(bp
->b_cmd
== BUF_CMD_WRITE
|| (bp
->b_flags
& B_CACHE
) == 0);
4084 if (bp
->b_flags
& B_VMIO
) {
4088 KASSERT(bp
->b_loffset
!= NOOFFSET
,
4089 ("vfs_busy_pages: no buffer offset"));
4092 * Busy all the pages. We have to busy them all at once
4093 * to avoid deadlocks.
4096 for (i
= 0; i
< bp
->b_xio
.xio_npages
; i
++) {
4097 vm_page_t m
= bp
->b_xio
.xio_pages
[i
];
4099 if (vm_page_busy_try(m
, FALSE
)) {
4100 vm_page_sleep_busy(m
, FALSE
, "vbpage");
4102 vm_page_wakeup(bp
->b_xio
.xio_pages
[i
]);
4108 * Setup for I/O, soft-busy the page right now because
4109 * the next loop may block.
4111 for (i
= 0; i
< bp
->b_xio
.xio_npages
; i
++) {
4112 vm_page_t m
= bp
->b_xio
.xio_pages
[i
];
4114 vm_page_flag_clear(m
, PG_ZERO
);
4115 if ((bp
->b_flags
& B_CLUSTER
) == 0) {
4116 vm_object_pip_add(obj
, 1);
4117 vm_page_io_start(m
);
4122 * Adjust protections for I/O and do bogus-page mapping.
4123 * Assume that vm_page_protect() can block (it can block
4124 * if VM_PROT_NONE, don't take any chances regardless).
4126 * In particular note that for writes we must incorporate
4127 * page dirtyness from the VM system into the buffer's
4130 * For reads we theoretically must incorporate page dirtyness
4131 * from the VM system to determine if the page needs bogus
4132 * replacement, but we shortcut the test by simply checking
4133 * that all m->valid bits are set, indicating that the page
4134 * is fully valid and does not need to be re-read. For any
4135 * VM system dirtyness the page will also be fully valid
4136 * since it was mapped at one point.
4139 for (i
= 0; i
< bp
->b_xio
.xio_npages
; i
++) {
4140 vm_page_t m
= bp
->b_xio
.xio_pages
[i
];
4142 vm_page_flag_clear(m
, PG_ZERO
); /* XXX */
4143 if (bp
->b_cmd
== BUF_CMD_WRITE
) {
4145 * When readying a vnode-backed buffer for
4146 * a write we must zero-fill any invalid
4147 * portions of the backing VM pages, mark
4148 * it valid and clear related dirty bits.
4150 * vfs_clean_one_page() incorporates any
4151 * VM dirtyness and updates the b_dirtyoff
4152 * range (after we've made the page RO).
4154 * It is also expected that the pmap modified
4155 * bit has already been cleared by the
4156 * vm_page_protect(). We may not be able
4157 * to clear all dirty bits for a page if it
4158 * was also memory mapped (NFS).
4160 * Finally be sure to unassign any swap-cache
4161 * backing store as it is now stale.
4163 vm_page_protect(m
, VM_PROT_READ
);
4164 vfs_clean_one_page(bp
, i
, m
);
4165 swap_pager_unswapped(m
);
4166 } else if (m
->valid
== VM_PAGE_BITS_ALL
) {
4168 * When readying a vnode-backed buffer for
4169 * read we must replace any dirty pages with
4170 * a bogus page so dirty data is not destroyed
4171 * when filling gaps.
4173 * To avoid testing whether the page is
4174 * dirty we instead test that the page was
4175 * at some point mapped (m->valid fully
4176 * valid) with the understanding that
4177 * this also covers the dirty case.
4179 bp
->b_xio
.xio_pages
[i
] = bogus_page
;
4180 bp
->b_flags
|= B_HASBOGUS
;
4182 } else if (m
->valid
& m
->dirty
) {
4184 * This case should not occur as partial
4185 * dirtyment can only happen if the buffer
4186 * is B_CACHE, and this code is not entered
4187 * if the buffer is B_CACHE.
4189 kprintf("Warning: vfs_busy_pages - page not "
4190 "fully valid! loff=%jx bpf=%08x "
4191 "idx=%d val=%02x dir=%02x\n",
4192 (uintmax_t)bp
->b_loffset
, bp
->b_flags
,
4193 i
, m
->valid
, m
->dirty
);
4194 vm_page_protect(m
, VM_PROT_NONE
);
4197 * The page is not valid and can be made
4200 vm_page_protect(m
, VM_PROT_NONE
);
4205 pmap_qenter(trunc_page((vm_offset_t
)bp
->b_data
),
4206 bp
->b_xio
.xio_pages
, bp
->b_xio
.xio_npages
);
4211 * This is the easiest place to put the process accounting for the I/O
4215 if (bp
->b_cmd
== BUF_CMD_READ
)
4216 lp
->lwp_ru
.ru_inblock
++;
4218 lp
->lwp_ru
.ru_oublock
++;
4223 * Tell the VM system that the pages associated with this buffer
4224 * are clean. This is used for delayed writes where the data is
4225 * going to go to disk eventually without additional VM intevention.
4227 * NOTE: While we only really need to clean through to b_bcount, we
4228 * just go ahead and clean through to b_bufsize.
4231 vfs_clean_pages(struct buf
*bp
)
4236 if ((bp
->b_flags
& B_VMIO
) == 0)
4239 KASSERT(bp
->b_loffset
!= NOOFFSET
,
4240 ("vfs_clean_pages: no buffer offset"));
4242 for (i
= 0; i
< bp
->b_xio
.xio_npages
; i
++) {
4243 m
= bp
->b_xio
.xio_pages
[i
];
4244 vfs_clean_one_page(bp
, i
, m
);
4249 * vfs_clean_one_page:
4251 * Set the valid bits and clear the dirty bits in a page within a
4252 * buffer. The range is restricted to the buffer's size and the
4253 * buffer's logical offset might index into the first page.
4255 * The caller has busied or soft-busied the page and it is not mapped,
4256 * test and incorporate the dirty bits into b_dirtyoff/end before
4257 * clearing them. Note that we need to clear the pmap modified bits
4258 * after determining the the page was dirty, vm_page_set_validclean()
4259 * does not do it for us.
4261 * This routine is typically called after a read completes (dirty should
4262 * be zero in that case as we are not called on bogus-replace pages),
4263 * or before a write is initiated.
4266 vfs_clean_one_page(struct buf
*bp
, int pageno
, vm_page_t m
)
4274 * Calculate offset range within the page but relative to buffer's
4275 * loffset. loffset might be offset into the first page.
4277 xoff
= (int)bp
->b_loffset
& PAGE_MASK
; /* loffset offset into pg 0 */
4278 bcount
= bp
->b_bcount
+ xoff
; /* offset adjusted */
4284 soff
= (pageno
<< PAGE_SHIFT
);
4285 eoff
= soff
+ PAGE_SIZE
;
4293 * Test dirty bits and adjust b_dirtyoff/end.
4295 * If dirty pages are incorporated into the bp any prior
4296 * B_NEEDCOMMIT state (NFS) must be cleared because the
4297 * caller has not taken into account the new dirty data.
4299 * If the page was memory mapped the dirty bits might go beyond the
4300 * end of the buffer, but we can't really make the assumption that
4301 * a file EOF straddles the buffer (even though this is the case for
4302 * NFS if B_NEEDCOMMIT is also set). So for the purposes of clearing
4303 * B_NEEDCOMMIT we only test the dirty bits covered by the buffer.
4304 * This also saves some console spam.
4306 * When clearing B_NEEDCOMMIT we must also clear B_CLUSTEROK,
4307 * NFS can handle huge commits but not huge writes.
4309 vm_page_test_dirty(m
);
4311 if ((bp
->b_flags
& B_NEEDCOMMIT
) &&
4312 (m
->dirty
& vm_page_bits(soff
& PAGE_MASK
, eoff
- soff
))) {
4314 kprintf("Warning: vfs_clean_one_page: bp %p "
4315 "loff=%jx,%d flgs=%08x clr B_NEEDCOMMIT"
4316 " cmd %d vd %02x/%02x x/s/e %d %d %d "
4318 bp
, (uintmax_t)bp
->b_loffset
, bp
->b_bcount
,
4319 bp
->b_flags
, bp
->b_cmd
,
4320 m
->valid
, m
->dirty
, xoff
, soff
, eoff
,
4321 bp
->b_dirtyoff
, bp
->b_dirtyend
);
4322 bp
->b_flags
&= ~(B_NEEDCOMMIT
| B_CLUSTEROK
);
4324 print_backtrace(-1);
4327 * Only clear the pmap modified bits if ALL the dirty bits
4328 * are set, otherwise the system might mis-clear portions
4331 if (m
->dirty
== VM_PAGE_BITS_ALL
&&
4332 (bp
->b_flags
& B_NEEDCOMMIT
) == 0) {
4333 pmap_clear_modify(m
);
4335 if (bp
->b_dirtyoff
> soff
- xoff
)
4336 bp
->b_dirtyoff
= soff
- xoff
;
4337 if (bp
->b_dirtyend
< eoff
- xoff
)
4338 bp
->b_dirtyend
= eoff
- xoff
;
4342 * Set related valid bits, clear related dirty bits.
4343 * Does not mess with the pmap modified bit.
4345 * WARNING! We cannot just clear all of m->dirty here as the
4346 * buffer cache buffers may use a DEV_BSIZE'd aligned
4347 * block size, or have an odd size (e.g. NFS at file EOF).
4348 * The putpages code can clear m->dirty to 0.
4350 * If a VOP_WRITE generates a buffer cache buffer which
4351 * covers the same space as mapped writable pages the
4352 * buffer flush might not be able to clear all the dirty
4353 * bits and still require a putpages from the VM system
4356 * WARNING! vm_page_set_validclean() currently assumes vm_token
4357 * is held. The page might not be busied (bdwrite() case).
4358 * XXX remove this comment once we've validated that this
4359 * is no longer an issue.
4361 vm_page_set_validclean(m
, soff
& PAGE_MASK
, eoff
- soff
);
4366 * Similar to vfs_clean_one_page() but sets the bits to valid and dirty.
4367 * The page data is assumed to be valid (there is no zeroing here).
4370 vfs_dirty_one_page(struct buf
*bp
, int pageno
, vm_page_t m
)
4378 * Calculate offset range within the page but relative to buffer's
4379 * loffset. loffset might be offset into the first page.
4381 xoff
= (int)bp
->b_loffset
& PAGE_MASK
; /* loffset offset into pg 0 */
4382 bcount
= bp
->b_bcount
+ xoff
; /* offset adjusted */
4388 soff
= (pageno
<< PAGE_SHIFT
);
4389 eoff
= soff
+ PAGE_SIZE
;
4395 vm_page_set_validdirty(m
, soff
& PAGE_MASK
, eoff
- soff
);
4402 * Clear a buffer. This routine essentially fakes an I/O, so we need
4403 * to clear B_ERROR and B_INVAL.
4405 * Note that while we only theoretically need to clear through b_bcount,
4406 * we go ahead and clear through b_bufsize.
4410 vfs_bio_clrbuf(struct buf
*bp
)
4414 if ((bp
->b_flags
& (B_VMIO
| B_MALLOC
)) == B_VMIO
) {
4415 bp
->b_flags
&= ~(B_INVAL
| B_EINTR
| B_ERROR
);
4416 if ((bp
->b_xio
.xio_npages
== 1) && (bp
->b_bufsize
< PAGE_SIZE
) &&
4417 (bp
->b_loffset
& PAGE_MASK
) == 0) {
4418 mask
= (1 << (bp
->b_bufsize
/ DEV_BSIZE
)) - 1;
4419 if ((bp
->b_xio
.xio_pages
[0]->valid
& mask
) == mask
) {
4423 if (((bp
->b_xio
.xio_pages
[0]->flags
& PG_ZERO
) == 0) &&
4424 ((bp
->b_xio
.xio_pages
[0]->valid
& mask
) == 0)) {
4425 bzero(bp
->b_data
, bp
->b_bufsize
);
4426 bp
->b_xio
.xio_pages
[0]->valid
|= mask
;
4432 for(i
=0;i
<bp
->b_xio
.xio_npages
;i
++,sa
=ea
) {
4433 int j
= ((vm_offset_t
)sa
& PAGE_MASK
) / DEV_BSIZE
;
4434 ea
= (caddr_t
)trunc_page((vm_offset_t
)sa
+ PAGE_SIZE
);
4435 ea
= (caddr_t
)(vm_offset_t
)ulmin(
4436 (u_long
)(vm_offset_t
)ea
,
4437 (u_long
)(vm_offset_t
)bp
->b_data
+ bp
->b_bufsize
);
4438 mask
= ((1 << ((ea
- sa
) / DEV_BSIZE
)) - 1) << j
;
4439 if ((bp
->b_xio
.xio_pages
[i
]->valid
& mask
) == mask
)
4441 if ((bp
->b_xio
.xio_pages
[i
]->valid
& mask
) == 0) {
4442 if ((bp
->b_xio
.xio_pages
[i
]->flags
& PG_ZERO
) == 0) {
4446 for (; sa
< ea
; sa
+= DEV_BSIZE
, j
++) {
4447 if (((bp
->b_xio
.xio_pages
[i
]->flags
& PG_ZERO
) == 0) &&
4448 (bp
->b_xio
.xio_pages
[i
]->valid
& (1<<j
)) == 0)
4449 bzero(sa
, DEV_BSIZE
);
4452 bp
->b_xio
.xio_pages
[i
]->valid
|= mask
;
4453 vm_page_flag_clear(bp
->b_xio
.xio_pages
[i
], PG_ZERO
);
4462 * vm_hold_load_pages:
4464 * Load pages into the buffer's address space. The pages are
4465 * allocated from the kernel object in order to reduce interference
4466 * with the any VM paging I/O activity. The range of loaded
4467 * pages will be wired.
4469 * If a page cannot be allocated, the 'pagedaemon' is woken up to
4470 * retrieve the full range (to - from) of pages.
4473 vm_hold_load_pages(struct buf
*bp
, vm_offset_t from
, vm_offset_t to
)
4479 to
= round_page(to
);
4480 from
= round_page(from
);
4481 index
= (from
- trunc_page((vm_offset_t
)bp
->b_data
)) >> PAGE_SHIFT
;
4486 * Note: must allocate system pages since blocking here
4487 * could intefere with paging I/O, no matter which
4490 vm_object_hold(&kernel_object
);
4491 p
= bio_page_alloc(bp
, &kernel_object
, pg
>> PAGE_SHIFT
,
4492 (vm_pindex_t
)((to
- pg
) >> PAGE_SHIFT
));
4493 vm_object_drop(&kernel_object
);
4496 p
->valid
= VM_PAGE_BITS_ALL
;
4497 vm_page_flag_clear(p
, PG_ZERO
);
4498 pmap_kenter_noinval(pg
, VM_PAGE_TO_PHYS(p
));
4499 bp
->b_xio
.xio_pages
[index
] = p
;
4506 pmap_invalidate_range(&kernel_pmap
, from
, to
);
4507 bp
->b_xio
.xio_npages
= index
;
4511 * Allocate a page for a buffer cache buffer.
4513 * If NULL is returned the caller is expected to retry (typically check if
4514 * the page already exists on retry before trying to allocate one).
4516 * NOTE! Low-memory handling is dealt with in b[q]relse(), not here. This
4517 * function will use the system reserve with the hope that the page
4518 * allocations can be returned to PQ_CACHE/PQ_FREE when the caller
4519 * is done with the buffer.
4521 * NOTE! However, TMPFS is a special case because flushing a dirty buffer
4522 * to TMPFS doesn't clean the page. For TMPFS, only the pagedaemon
4523 * is capable of retiring pages (to swap). For TMPFS we don't dig
4524 * into the system reserve because doing so could stall out pretty
4525 * much every process running on the system.
4529 bio_page_alloc(struct buf
*bp
, vm_object_t obj
, vm_pindex_t pg
, int deficit
)
4531 int vmflags
= VM_ALLOC_NORMAL
| VM_ALLOC_NULL_OK
;
4534 ASSERT_LWKT_TOKEN_HELD(vm_object_token(obj
));
4537 * Try a normal allocation first.
4539 p
= vm_page_alloc(obj
, pg
, vmflags
);
4542 if (vm_page_lookup(obj
, pg
))
4544 vm_pageout_deficit
+= deficit
;
4547 * Try again, digging into the system reserve.
4549 * Trying to recover pages from the buffer cache here can deadlock
4550 * against other threads trying to busy underlying pages so we
4551 * depend on the code in brelse() and bqrelse() to free/cache the
4552 * underlying buffer cache pages when memory is low.
4554 if (curthread
->td_flags
& TDF_SYSTHREAD
)
4555 vmflags
|= VM_ALLOC_SYSTEM
| VM_ALLOC_INTERRUPT
;
4556 else if (bp
->b_vp
&& bp
->b_vp
->v_tag
== VT_TMPFS
)
4559 vmflags
|= VM_ALLOC_SYSTEM
;
4561 /*recoverbufpages();*/
4562 p
= vm_page_alloc(obj
, pg
, vmflags
);
4565 if (vm_page_lookup(obj
, pg
))
4569 * Wait for memory to free up and try again
4571 if (vm_page_count_severe())
4573 vm_wait(hz
/ 20 + 1);
4575 p
= vm_page_alloc(obj
, pg
, vmflags
);
4578 if (vm_page_lookup(obj
, pg
))
4582 * Ok, now we are really in trouble.
4585 static struct krate biokrate
= { .freq
= 1 };
4586 krateprintf(&biokrate
,
4587 "Warning: bio_page_alloc: memory exhausted "
4588 "during buffer cache page allocation from %s\n",
4589 curthread
->td_comm
);
4591 if (curthread
->td_flags
& TDF_SYSTHREAD
)
4592 vm_wait(hz
/ 20 + 1);
4594 vm_wait(hz
/ 2 + 1);
4599 * vm_hold_free_pages:
4601 * Return pages associated with the buffer back to the VM system.
4603 * The range of pages underlying the buffer's address space will
4604 * be unmapped and un-wired.
4607 vm_hold_free_pages(struct buf
*bp
, vm_offset_t from
, vm_offset_t to
)
4611 int index
, newnpages
;
4613 from
= round_page(from
);
4614 to
= round_page(to
);
4615 index
= (from
- trunc_page((vm_offset_t
)bp
->b_data
)) >> PAGE_SHIFT
;
4618 for (pg
= from
; pg
< to
; pg
+= PAGE_SIZE
, index
++) {
4619 p
= bp
->b_xio
.xio_pages
[index
];
4620 if (p
&& (index
< bp
->b_xio
.xio_npages
)) {
4622 kprintf("vm_hold_free_pages: doffset: %lld, "
4624 (long long)bp
->b_bio2
.bio_offset
,
4625 (long long)bp
->b_loffset
);
4627 bp
->b_xio
.xio_pages
[index
] = NULL
;
4628 pmap_kremove_noinval(pg
);
4629 vm_page_busy_wait(p
, FALSE
, "vmhldpg");
4630 vm_page_unwire(p
, 0);
4634 pmap_invalidate_range(&kernel_pmap
, from
, to
);
4635 bp
->b_xio
.xio_npages
= newnpages
;
4641 * Map a user buffer into KVM via a pbuf. On return the buffer's
4642 * b_data, b_bufsize, and b_bcount will be set, and its XIO page array
4646 vmapbuf(struct buf
*bp
, caddr_t udata
, int bytes
)
4657 * bp had better have a command and it better be a pbuf.
4659 KKASSERT(bp
->b_cmd
!= BUF_CMD_DONE
);
4660 KKASSERT(bp
->b_flags
& B_PAGING
);
4661 KKASSERT(bp
->b_kvabase
);
4667 * Map the user data into KVM. Mappings have to be page-aligned.
4669 addr
= (caddr_t
)trunc_page((vm_offset_t
)udata
);
4672 vmprot
= VM_PROT_READ
;
4673 if (bp
->b_cmd
== BUF_CMD_READ
)
4674 vmprot
|= VM_PROT_WRITE
;
4676 while (addr
< udata
+ bytes
) {
4678 * Do the vm_fault if needed; do the copy-on-write thing
4679 * when reading stuff off device into memory.
4681 * vm_fault_page*() returns a held VM page.
4683 va
= (addr
>= udata
) ? (vm_offset_t
)addr
: (vm_offset_t
)udata
;
4684 va
= trunc_page(va
);
4686 m
= vm_fault_page_quick(va
, vmprot
, &error
);
4688 for (i
= 0; i
< pidx
; ++i
) {
4689 vm_page_unhold(bp
->b_xio
.xio_pages
[i
]);
4690 bp
->b_xio
.xio_pages
[i
] = NULL
;
4694 bp
->b_xio
.xio_pages
[pidx
] = m
;
4700 * Map the page array and set the buffer fields to point to
4701 * the mapped data buffer.
4703 if (pidx
> btoc(MAXPHYS
))
4704 panic("vmapbuf: mapped more than MAXPHYS");
4705 pmap_qenter((vm_offset_t
)bp
->b_kvabase
, bp
->b_xio
.xio_pages
, pidx
);
4707 bp
->b_xio
.xio_npages
= pidx
;
4708 bp
->b_data
= bp
->b_kvabase
+ ((int)(intptr_t)udata
& PAGE_MASK
);
4709 bp
->b_bcount
= bytes
;
4710 bp
->b_bufsize
= bytes
;
4717 * Free the io map PTEs associated with this IO operation.
4718 * We also invalidate the TLB entries and restore the original b_addr.
4721 vunmapbuf(struct buf
*bp
)
4726 KKASSERT(bp
->b_flags
& B_PAGING
);
4728 npages
= bp
->b_xio
.xio_npages
;
4729 pmap_qremove(trunc_page((vm_offset_t
)bp
->b_data
), npages
);
4730 for (pidx
= 0; pidx
< npages
; ++pidx
) {
4731 vm_page_unhold(bp
->b_xio
.xio_pages
[pidx
]);
4732 bp
->b_xio
.xio_pages
[pidx
] = NULL
;
4734 bp
->b_xio
.xio_npages
= 0;
4735 bp
->b_data
= bp
->b_kvabase
;
4739 * Scan all buffers in the system and issue the callback.
4742 scan_all_buffers(int (*callback
)(struct buf
*, void *), void *info
)
4748 for (n
= 0; n
< nbuf
; ++n
) {
4749 if ((error
= callback(&buf
[n
], info
)) < 0) {
4759 * nestiobuf_iodone: biodone callback for nested buffers and propagate
4760 * completion to the master buffer.
4763 nestiobuf_iodone(struct bio
*bio
)
4766 struct buf
*mbp
, *bp
;
4767 struct devstat
*stats
;
4772 mbio
= bio
->bio_caller_info1
.ptr
;
4773 stats
= bio
->bio_caller_info2
.ptr
;
4774 mbp
= mbio
->bio_buf
;
4776 KKASSERT(bp
->b_bcount
<= bp
->b_bufsize
);
4777 KKASSERT(mbp
!= bp
);
4779 error
= bp
->b_error
;
4780 if (bp
->b_error
== 0 &&
4781 (bp
->b_bcount
< bp
->b_bufsize
|| bp
->b_resid
> 0)) {
4783 * Not all got transfered, raise an error. We have no way to
4784 * propagate these conditions to mbp.
4789 donebytes
= bp
->b_bufsize
;
4793 nestiobuf_done(mbio
, donebytes
, error
, stats
);
4797 nestiobuf_done(struct bio
*mbio
, int donebytes
, int error
, struct devstat
*stats
)
4801 mbp
= mbio
->bio_buf
;
4803 KKASSERT((int)(intptr_t)mbio
->bio_driver_info
> 0);
4806 * If an error occured, propagate it to the master buffer.
4808 * Several biodone()s may wind up running concurrently so
4809 * use an atomic op to adjust b_flags.
4812 mbp
->b_error
= error
;
4813 atomic_set_int(&mbp
->b_flags
, B_ERROR
);
4817 * Decrement the operations in progress counter and terminate the
4818 * I/O if this was the last bit.
4820 if (atomic_fetchadd_int((int *)&mbio
->bio_driver_info
, -1) == 1) {
4823 devstat_end_transaction_buf(stats
, mbp
);
4829 * Initialize a nestiobuf for use. Set an initial count of 1 to prevent
4830 * the mbio from being biodone()'d while we are still adding sub-bios to
4834 nestiobuf_init(struct bio
*bio
)
4836 bio
->bio_driver_info
= (void *)1;
4840 * The BIOs added to the nestedio have already been started, remove the
4841 * count that placeheld our mbio and biodone() it if the count would
4845 nestiobuf_start(struct bio
*mbio
)
4847 struct buf
*mbp
= mbio
->bio_buf
;
4850 * Decrement the operations in progress counter and terminate the
4851 * I/O if this was the last bit.
4853 if (atomic_fetchadd_int((int *)&mbio
->bio_driver_info
, -1) == 1) {
4854 if (mbp
->b_flags
& B_ERROR
)
4855 mbp
->b_resid
= mbp
->b_bcount
;
4863 * Set an intermediate error prior to calling nestiobuf_start()
4866 nestiobuf_error(struct bio
*mbio
, int error
)
4868 struct buf
*mbp
= mbio
->bio_buf
;
4871 mbp
->b_error
= error
;
4872 atomic_set_int(&mbp
->b_flags
, B_ERROR
);
4877 * nestiobuf_add: setup a "nested" buffer.
4879 * => 'mbp' is a "master" buffer which is being divided into sub pieces.
4880 * => 'bp' should be a buffer allocated by getiobuf.
4881 * => 'offset' is a byte offset in the master buffer.
4882 * => 'size' is a size in bytes of this nested buffer.
4885 nestiobuf_add(struct bio
*mbio
, struct buf
*bp
, int offset
, size_t size
, struct devstat
*stats
)
4887 struct buf
*mbp
= mbio
->bio_buf
;
4888 struct vnode
*vp
= mbp
->b_vp
;
4890 KKASSERT(mbp
->b_bcount
>= offset
+ size
);
4892 atomic_add_int((int *)&mbio
->bio_driver_info
, 1);
4894 /* kernel needs to own the lock for it to be released in biodone */
4897 bp
->b_cmd
= mbp
->b_cmd
;
4898 bp
->b_bio1
.bio_done
= nestiobuf_iodone
;
4899 bp
->b_data
= (char *)mbp
->b_data
+ offset
;
4900 bp
->b_resid
= bp
->b_bcount
= size
;
4901 bp
->b_bufsize
= bp
->b_bcount
;
4903 bp
->b_bio1
.bio_track
= NULL
;
4904 bp
->b_bio1
.bio_caller_info1
.ptr
= mbio
;
4905 bp
->b_bio1
.bio_caller_info2
.ptr
= stats
;
4910 DB_SHOW_COMMAND(buffer
, db_show_buffer
)
4913 struct buf
*bp
= (struct buf
*)addr
;
4916 db_printf("usage: show buffer <addr>\n");
4920 db_printf("b_flags = 0x%b\n", (u_int
)bp
->b_flags
, PRINT_BUF_FLAGS
);
4921 db_printf("b_cmd = %d\n", bp
->b_cmd
);
4922 db_printf("b_error = %d, b_bufsize = %d, b_bcount = %d, "
4923 "b_resid = %d\n, b_data = %p, "
4924 "bio_offset(disk) = %lld, bio_offset(phys) = %lld\n",
4925 bp
->b_error
, bp
->b_bufsize
, bp
->b_bcount
, bp
->b_resid
,
4927 (long long)bp
->b_bio2
.bio_offset
,
4928 (long long)(bp
->b_bio2
.bio_next
?
4929 bp
->b_bio2
.bio_next
->bio_offset
: (off_t
)-1));
4930 if (bp
->b_xio
.xio_npages
) {
4932 db_printf("b_xio.xio_npages = %d, pages(OBJ, IDX, PA): ",
4933 bp
->b_xio
.xio_npages
);
4934 for (i
= 0; i
< bp
->b_xio
.xio_npages
; i
++) {
4936 m
= bp
->b_xio
.xio_pages
[i
];
4937 db_printf("(%p, 0x%lx, 0x%lx)", (void *)m
->object
,
4938 (u_long
)m
->pindex
, (u_long
)VM_PAGE_TO_PHYS(m
));
4939 if ((i
+ 1) < bp
->b_xio
.xio_npages
)