2 * Copyright (c) 2004 Poul-Henning Kamp
3 * Copyright (c) 1994,1997 John S. Dyson
4 * Copyright (c) 2013 The FreeBSD Foundation
7 * Portions of this software were developed by Konstantin Belousov
8 * under sponsorship from the FreeBSD Foundation.
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in the
17 * documentation and/or other materials provided with the distribution.
19 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
22 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
33 * this file contains a new buffer I/O scheme implementing a coherent
34 * VM object and buffer cache scheme. Pains have been taken to make
35 * sure that the performance degradation associated with schemes such
36 * as this is not realized.
38 * Author: John S. Dyson
39 * Significant help during the development and debugging phases
40 * had been provided by David Greenman, also of the FreeBSD core team.
42 * see man buf(9) for more info.
45 #include <sys/cdefs.h>
46 __FBSDID("$FreeBSD$");
48 #include <sys/param.h>
49 #include <sys/systm.h>
53 #include <sys/devicestat.h>
54 #include <sys/eventhandler.h>
56 #include <sys/limits.h>
58 #include <sys/malloc.h>
59 #include <sys/mount.h>
60 #include <sys/mutex.h>
61 #include <sys/kernel.h>
62 #include <sys/kthread.h>
64 #include <sys/resourcevar.h>
65 #include <sys/rwlock.h>
66 #include <sys/sysctl.h>
67 #include <sys/sysproto.h>
69 #include <sys/vmmeter.h>
70 #include <sys/vnode.h>
71 #include <sys/watchdog.h>
72 #include <geom/geom.h>
74 #include <vm/vm_param.h>
75 #include <vm/vm_kern.h>
76 #include <vm/vm_pageout.h>
77 #include <vm/vm_page.h>
78 #include <vm/vm_object.h>
79 #include <vm/vm_extern.h>
80 #include <vm/vm_map.h>
81 #include <vm/swap_pager.h>
82 #include "opt_compat.h"
85 static MALLOC_DEFINE(M_BIOBUF, "biobuf", "BIO buffer");
87 struct bio_ops bioops; /* I/O operation notification */
89 struct buf_ops buf_ops_bio = {
90 .bop_name = "buf_ops_bio",
91 .bop_write = bufwrite,
92 .bop_strategy = bufstrategy,
94 .bop_bdflush = bufbdflush,
97 static struct buf *buf; /* buffer header pool */
98 extern struct buf *swbuf; /* Swap buffer header pool. */
101 /* Used below and for softdep flushing threads in ufs/ffs/ffs_softdep.c */
102 struct proc *bufdaemonproc;
104 static int inmem(struct vnode *vp, daddr_t blkno);
105 static void vm_hold_free_pages(struct buf *bp, int newbsize);
106 static void vm_hold_load_pages(struct buf *bp, vm_offset_t from,
108 static void vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, vm_page_t m);
109 static void vfs_page_set_validclean(struct buf *bp, vm_ooffset_t off,
111 static void vfs_clean_pages_dirty_buf(struct buf *bp);
112 static void vfs_setdirty_locked_object(struct buf *bp);
113 static void vfs_vmio_release(struct buf *bp);
114 static int vfs_bio_clcheck(struct vnode *vp, int size,
115 daddr_t lblkno, daddr_t blkno);
116 static int buf_flush(struct vnode *vp, int);
117 static int flushbufqueues(struct vnode *, int, int);
118 static void buf_daemon(void);
119 static void bremfreel(struct buf *bp);
120 static __inline void bd_wakeup(void);
121 static int sysctl_runningspace(SYSCTL_HANDLER_ARGS);
122 #if defined(COMPAT_FREEBSD4) || defined(COMPAT_FREEBSD5) || \
123 defined(COMPAT_FREEBSD6) || defined(COMPAT_FREEBSD7)
124 static int sysctl_bufspace(SYSCTL_HANDLER_ARGS);
127 int vmiodirenable = TRUE;
128 SYSCTL_INT(_vfs, OID_AUTO, vmiodirenable, CTLFLAG_RW, &vmiodirenable, 0,
129 "Use the VM system for directory writes");
130 long runningbufspace;
131 SYSCTL_LONG(_vfs, OID_AUTO, runningbufspace, CTLFLAG_RD, &runningbufspace, 0,
132 "Amount of presently outstanding async buffer io");
133 static long bufspace;
134 #if defined(COMPAT_FREEBSD4) || defined(COMPAT_FREEBSD5) || \
135 defined(COMPAT_FREEBSD6) || defined(COMPAT_FREEBSD7)
136 SYSCTL_PROC(_vfs, OID_AUTO, bufspace, CTLTYPE_LONG|CTLFLAG_MPSAFE|CTLFLAG_RD,
137 &bufspace, 0, sysctl_bufspace, "L", "Virtual memory used for buffers");
139 SYSCTL_LONG(_vfs, OID_AUTO, bufspace, CTLFLAG_RD, &bufspace, 0,
140 "Physical memory used for buffers");
142 static long bufkvaspace;
143 SYSCTL_LONG(_vfs, OID_AUTO, bufkvaspace, CTLFLAG_RD, &bufkvaspace, 0,
144 "Kernel virtual memory used for buffers");
145 static long maxbufspace;
146 SYSCTL_LONG(_vfs, OID_AUTO, maxbufspace, CTLFLAG_RD, &maxbufspace, 0,
147 "Maximum allowed value of bufspace (including buf_daemon)");
148 static long bufmallocspace;
149 SYSCTL_LONG(_vfs, OID_AUTO, bufmallocspace, CTLFLAG_RD, &bufmallocspace, 0,
150 "Amount of malloced memory for buffers");
151 static long maxbufmallocspace;
152 SYSCTL_LONG(_vfs, OID_AUTO, maxmallocbufspace, CTLFLAG_RW, &maxbufmallocspace, 0,
153 "Maximum amount of malloced memory for buffers");
154 static long lobufspace;
155 SYSCTL_LONG(_vfs, OID_AUTO, lobufspace, CTLFLAG_RD, &lobufspace, 0,
156 "Minimum amount of buffers we want to have");
158 SYSCTL_LONG(_vfs, OID_AUTO, hibufspace, CTLFLAG_RD, &hibufspace, 0,
159 "Maximum allowed value of bufspace (excluding buf_daemon)");
160 static int bufreusecnt;
161 SYSCTL_INT(_vfs, OID_AUTO, bufreusecnt, CTLFLAG_RW, &bufreusecnt, 0,
162 "Number of times we have reused a buffer");
163 static int buffreekvacnt;
164 SYSCTL_INT(_vfs, OID_AUTO, buffreekvacnt, CTLFLAG_RW, &buffreekvacnt, 0,
165 "Number of times we have freed the KVA space from some buffer");
166 static int bufdefragcnt;
167 SYSCTL_INT(_vfs, OID_AUTO, bufdefragcnt, CTLFLAG_RW, &bufdefragcnt, 0,
168 "Number of times we have had to repeat buffer allocation to defragment");
169 static long lorunningspace;
170 SYSCTL_PROC(_vfs, OID_AUTO, lorunningspace, CTLTYPE_LONG | CTLFLAG_MPSAFE |
171 CTLFLAG_RW, &lorunningspace, 0, sysctl_runningspace, "L",
172 "Minimum preferred space used for in-progress I/O");
173 static long hirunningspace;
174 SYSCTL_PROC(_vfs, OID_AUTO, hirunningspace, CTLTYPE_LONG | CTLFLAG_MPSAFE |
175 CTLFLAG_RW, &hirunningspace, 0, sysctl_runningspace, "L",
176 "Maximum amount of space to use for in-progress I/O");
177 int dirtybufferflushes;
178 SYSCTL_INT(_vfs, OID_AUTO, dirtybufferflushes, CTLFLAG_RW, &dirtybufferflushes,
179 0, "Number of bdwrite to bawrite conversions to limit dirty buffers");
181 SYSCTL_INT(_vfs, OID_AUTO, bdwriteskip, CTLFLAG_RW, &bdwriteskip,
182 0, "Number of buffers supplied to bdwrite with snapshot deadlock risk");
183 int altbufferflushes;
184 SYSCTL_INT(_vfs, OID_AUTO, altbufferflushes, CTLFLAG_RW, &altbufferflushes,
185 0, "Number of fsync flushes to limit dirty buffers");
186 static int recursiveflushes;
187 SYSCTL_INT(_vfs, OID_AUTO, recursiveflushes, CTLFLAG_RW, &recursiveflushes,
188 0, "Number of flushes skipped due to being recursive");
189 static int numdirtybuffers;
190 SYSCTL_INT(_vfs, OID_AUTO, numdirtybuffers, CTLFLAG_RD, &numdirtybuffers, 0,
191 "Number of buffers that are dirty (has unwritten changes) at the moment");
192 static int lodirtybuffers;
193 SYSCTL_INT(_vfs, OID_AUTO, lodirtybuffers, CTLFLAG_RW, &lodirtybuffers, 0,
194 "How many buffers we want to have free before bufdaemon can sleep");
195 static int hidirtybuffers;
196 SYSCTL_INT(_vfs, OID_AUTO, hidirtybuffers, CTLFLAG_RW, &hidirtybuffers, 0,
197 "When the number of dirty buffers is considered severe");
199 SYSCTL_INT(_vfs, OID_AUTO, dirtybufthresh, CTLFLAG_RW, &dirtybufthresh,
200 0, "Number of bdwrite to bawrite conversions to clear dirty buffers");
201 static int numfreebuffers;
202 SYSCTL_INT(_vfs, OID_AUTO, numfreebuffers, CTLFLAG_RD, &numfreebuffers, 0,
203 "Number of free buffers");
204 static int lofreebuffers;
205 SYSCTL_INT(_vfs, OID_AUTO, lofreebuffers, CTLFLAG_RW, &lofreebuffers, 0,
207 static int hifreebuffers;
208 SYSCTL_INT(_vfs, OID_AUTO, hifreebuffers, CTLFLAG_RW, &hifreebuffers, 0,
209 "XXX Complicatedly unused");
210 static int getnewbufcalls;
211 SYSCTL_INT(_vfs, OID_AUTO, getnewbufcalls, CTLFLAG_RW, &getnewbufcalls, 0,
212 "Number of calls to getnewbuf");
213 static int getnewbufrestarts;
214 SYSCTL_INT(_vfs, OID_AUTO, getnewbufrestarts, CTLFLAG_RW, &getnewbufrestarts, 0,
215 "Number of times getnewbuf has had to restart a buffer aquisition");
216 static int mappingrestarts;
217 SYSCTL_INT(_vfs, OID_AUTO, mappingrestarts, CTLFLAG_RW, &mappingrestarts, 0,
218 "Number of times getblk has had to restart a buffer mapping for "
220 static int flushbufqtarget = 100;
221 SYSCTL_INT(_vfs, OID_AUTO, flushbufqtarget, CTLFLAG_RW, &flushbufqtarget, 0,
222 "Amount of work to do in flushbufqueues when helping bufdaemon");
223 static long notbufdflushes;
224 SYSCTL_LONG(_vfs, OID_AUTO, notbufdflushes, CTLFLAG_RD, ¬bufdflushes, 0,
225 "Number of dirty buffer flushes done by the bufdaemon helpers");
226 static long barrierwrites;
227 SYSCTL_LONG(_vfs, OID_AUTO, barrierwrites, CTLFLAG_RW, &barrierwrites, 0,
228 "Number of barrier writes");
229 SYSCTL_INT(_vfs, OID_AUTO, unmapped_buf_allowed, CTLFLAG_RD,
230 &unmapped_buf_allowed, 0,
231 "Permit the use of the unmapped i/o");
234 * Lock for the non-dirty bufqueues
236 static struct mtx_padalign bqclean;
239 * Lock for the dirty queue.
241 static struct mtx_padalign bqdirty;
244 * This lock synchronizes access to bd_request.
246 static struct mtx_padalign bdlock;
249 * This lock protects the runningbufreq and synchronizes runningbufwakeup and
250 * waitrunningbufspace().
252 static struct mtx_padalign rbreqlock;
255 * Lock that protects needsbuffer and the sleeps/wakeups surrounding it.
257 static struct rwlock_padalign nblock;
260 * Lock that protects bdirtywait.
262 static struct mtx_padalign bdirtylock;
265 * Wakeup point for bufdaemon, as well as indicator of whether it is already
266 * active. Set to 1 when the bufdaemon is already "on" the queue, 0 when it
269 static int bd_request;
272 * Request for the buf daemon to write more buffers than is indicated by
273 * lodirtybuf. This may be necessary to push out excess dependencies or
274 * defragment the address space where a simple count of the number of dirty
275 * buffers is insufficient to characterize the demand for flushing them.
277 static int bd_speedupreq;
280 * bogus page -- for I/O to/from partially complete buffers
281 * this is a temporary solution to the problem, but it is not
282 * really that bad. it would be better to split the buffer
283 * for input in the case of buffers partially already in memory,
284 * but the code is intricate enough already.
286 vm_page_t bogus_page;
289 * Synchronization (sleep/wakeup) variable for active buffer space requests.
290 * Set when wait starts, cleared prior to wakeup().
291 * Used in runningbufwakeup() and waitrunningbufspace().
293 static int runningbufreq;
296 * Synchronization (sleep/wakeup) variable for buffer requests.
297 * Can contain the VFS_BIO_NEED flags defined below; setting/clearing is done
299 * Used in numdirtywakeup(), bufspacewakeup(), bufcountadd(), bwillwrite(),
300 * getnewbuf(), and getblk().
302 static volatile int needsbuffer;
305 * Synchronization for bwillwrite() waiters.
307 static int bdirtywait;
310 * Definitions for the buffer free lists.
312 #define BUFFER_QUEUES 4 /* number of free buffer queues */
314 #define QUEUE_NONE 0 /* on no queue */
315 #define QUEUE_CLEAN 1 /* non-B_DELWRI buffers */
316 #define QUEUE_DIRTY 2 /* B_DELWRI buffers */
317 #define QUEUE_EMPTY 3 /* empty buffer headers */
318 #define QUEUE_SENTINEL 1024 /* not an queue index, but mark for sentinel */
320 /* Queues for free buffers with various properties */
321 static TAILQ_HEAD(bqueues, buf) bufqueues[BUFFER_QUEUES] = { { 0 } };
323 static int bq_len[BUFFER_QUEUES];
327 * Single global constant for BUF_WMESG, to avoid getting multiple references.
328 * buf_wmesg is referred from macros.
330 const char *buf_wmesg = BUF_WMESG;
332 #define VFS_BIO_NEED_ANY 0x01 /* any freeable buffer */
333 #define VFS_BIO_NEED_FREE 0x04 /* wait for free bufs, hi hysteresis */
334 #define VFS_BIO_NEED_BUFSPACE 0x08 /* wait for buf space, lo hysteresis */
337 sysctl_runningspace(SYSCTL_HANDLER_ARGS)
342 value = *(long *)arg1;
343 error = sysctl_handle_long(oidp, &value, 0, req);
344 if (error != 0 || req->newptr == NULL)
346 mtx_lock(&rbreqlock);
347 if (arg1 == &hirunningspace) {
348 if (value < lorunningspace)
351 hirunningspace = value;
353 KASSERT(arg1 == &lorunningspace,
354 ("%s: unknown arg1", __func__));
355 if (value > hirunningspace)
358 lorunningspace = value;
360 mtx_unlock(&rbreqlock);
364 #if defined(COMPAT_FREEBSD4) || defined(COMPAT_FREEBSD5) || \
365 defined(COMPAT_FREEBSD6) || defined(COMPAT_FREEBSD7)
367 sysctl_bufspace(SYSCTL_HANDLER_ARGS)
372 if (sizeof(int) == sizeof(long) || req->oldlen >= sizeof(long))
373 return (sysctl_handle_long(oidp, arg1, arg2, req));
374 lvalue = *(long *)arg1;
375 if (lvalue > INT_MAX)
376 /* On overflow, still write out a long to trigger ENOMEM. */
377 return (sysctl_handle_long(oidp, &lvalue, 0, req));
379 return (sysctl_handle_int(oidp, &ivalue, 0, req));
386 * Return the appropriate queue lock based on the index.
388 static inline struct mtx *
392 if (qindex == QUEUE_DIRTY)
393 return (struct mtx *)(&bqdirty);
394 return (struct mtx *)(&bqclean);
400 * Wakeup any bwillwrite() waiters.
405 mtx_lock(&bdirtylock);
410 mtx_unlock(&bdirtylock);
416 * Decrement the numdirtybuffers count by one and wakeup any
417 * threads blocked in bwillwrite().
423 if (atomic_fetchadd_int(&numdirtybuffers, -1) ==
424 (lodirtybuffers + hidirtybuffers) / 2)
431 * Increment the numdirtybuffers count by one and wakeup the buf
439 * Only do the wakeup once as we cross the boundary. The
440 * buf daemon will keep running until the condition clears.
442 if (atomic_fetchadd_int(&numdirtybuffers, 1) ==
443 (lodirtybuffers + hidirtybuffers) / 2)
450 * Called when buffer space is potentially available for recovery.
451 * getnewbuf() will block on this flag when it is unable to free
452 * sufficient buffer space. Buffer space becomes recoverable when
453 * bp's get placed back in the queues.
461 * If someone is waiting for bufspace, wake them up. Even
462 * though we may not have freed the kva space yet, the waiting
463 * process will be able to now.
469 if ((on & VFS_BIO_NEED_BUFSPACE) == 0)
472 if (atomic_cmpset_rel_int(&needsbuffer, on,
473 on & ~VFS_BIO_NEED_BUFSPACE))
477 wakeup(__DEVOLATILE(void *, &needsbuffer));
484 * Adjust the reported bufspace for a KVA managed buffer, possibly
485 * waking any waiters.
488 bufspaceadjust(struct buf *bp, int bufsize)
492 KASSERT((bp->b_flags & B_MALLOC) == 0,
493 ("bufspaceadjust: malloc buf %p", bp));
494 diff = bufsize - bp->b_bufsize;
496 atomic_subtract_long(&bufspace, -diff);
499 atomic_add_long(&bufspace, diff);
500 bp->b_bufsize = bufsize;
506 * Adjust the reported bufspace for a malloc managed buffer, possibly
507 * waking any waiters.
510 bufmallocadjust(struct buf *bp, int bufsize)
514 KASSERT((bp->b_flags & B_MALLOC) != 0,
515 ("bufmallocadjust: non-malloc buf %p", bp));
516 diff = bufsize - bp->b_bufsize;
518 atomic_subtract_long(&bufmallocspace, -diff);
521 atomic_add_long(&bufmallocspace, diff);
522 bp->b_bufsize = bufsize;
528 * Wake up processes that are waiting on asynchronous writes to fall
529 * below lorunningspace.
535 mtx_lock(&rbreqlock);
538 wakeup(&runningbufreq);
540 mtx_unlock(&rbreqlock);
546 * Decrement the outstanding write count according.
549 runningbufwakeup(struct buf *bp)
553 bspace = bp->b_runningbufspace;
556 space = atomic_fetchadd_long(&runningbufspace, -bspace);
557 KASSERT(space >= bspace, ("runningbufspace underflow %ld %ld",
559 bp->b_runningbufspace = 0;
561 * Only acquire the lock and wakeup on the transition from exceeding
562 * the threshold to falling below it.
564 if (space < lorunningspace)
566 if (space - bspace > lorunningspace)
574 * Called when a buffer has been added to one of the free queues to
575 * account for the buffer and to wakeup anyone waiting for free buffers.
576 * This typically occurs when large amounts of metadata are being handled
577 * by the buffer cache ( else buffer space runs out first, usually ).
580 bufcountadd(struct buf *bp)
582 int mask, need_wakeup, old, on;
584 KASSERT((bp->b_flags & B_INFREECNT) == 0,
585 ("buf %p already counted as free", bp));
586 bp->b_flags |= B_INFREECNT;
587 old = atomic_fetchadd_int(&numfreebuffers, 1);
588 KASSERT(old >= 0 && old < nbuf,
589 ("numfreebuffers climbed to %d", old + 1));
590 mask = VFS_BIO_NEED_ANY;
591 if (numfreebuffers >= hifreebuffers)
592 mask |= VFS_BIO_NEED_FREE;
600 if (atomic_cmpset_rel_int(&needsbuffer, on, on & ~mask))
604 wakeup(__DEVOLATILE(void *, &needsbuffer));
611 * Decrement the numfreebuffers count as needed.
614 bufcountsub(struct buf *bp)
619 * Fixup numfreebuffers count. If the buffer is invalid or not
620 * delayed-write, the buffer was free and we must decrement
623 if ((bp->b_flags & B_INVAL) || (bp->b_flags & B_DELWRI) == 0) {
624 KASSERT((bp->b_flags & B_INFREECNT) != 0,
625 ("buf %p not counted in numfreebuffers", bp));
626 bp->b_flags &= ~B_INFREECNT;
627 old = atomic_fetchadd_int(&numfreebuffers, -1);
628 KASSERT(old > 0, ("numfreebuffers dropped to %d", old - 1));
633 * waitrunningbufspace()
635 * runningbufspace is a measure of the amount of I/O currently
636 * running. This routine is used in async-write situations to
637 * prevent creating huge backups of pending writes to a device.
638 * Only asynchronous writes are governed by this function.
640 * This does NOT turn an async write into a sync write. It waits
641 * for earlier writes to complete and generally returns before the
642 * caller's write has reached the device.
645 waitrunningbufspace(void)
648 mtx_lock(&rbreqlock);
649 while (runningbufspace > hirunningspace) {
651 msleep(&runningbufreq, &rbreqlock, PVM, "wdrain", 0);
653 mtx_unlock(&rbreqlock);
658 * vfs_buf_test_cache:
660 * Called when a buffer is extended. This function clears the B_CACHE
661 * bit if the newly extended portion of the buffer does not contain
666 vfs_buf_test_cache(struct buf *bp,
667 vm_ooffset_t foff, vm_offset_t off, vm_offset_t size,
671 VM_OBJECT_ASSERT_LOCKED(m->object);
672 if (bp->b_flags & B_CACHE) {
673 int base = (foff + off) & PAGE_MASK;
674 if (vm_page_is_valid(m, base, size) == 0)
675 bp->b_flags &= ~B_CACHE;
679 /* Wake up the buffer daemon if necessary */
685 if (bd_request == 0) {
693 * bd_speedup - speedup the buffer cache flushing code
702 if (bd_speedupreq == 0 || bd_request == 0)
712 #define NSWBUF_MIN 16
716 #define TRANSIENT_DENOM 5
718 #define TRANSIENT_DENOM 10
722 * Calculating buffer cache scaling values and reserve space for buffer
723 * headers. This is called during low level kernel initialization and
724 * may be called more then once. We CANNOT write to the memory area
725 * being reserved at this time.
728 kern_vfs_bio_buffer_alloc(caddr_t v, long physmem_est)
731 long maxbuf, maxbuf_sz, buf_sz, biotmap_sz;
734 * physmem_est is in pages. Convert it to kilobytes (assumes
735 * PAGE_SIZE is >= 1K)
737 physmem_est = physmem_est * (PAGE_SIZE / 1024);
740 * The nominal buffer size (and minimum KVA allocation) is BKVASIZE.
741 * For the first 64MB of ram nominally allocate sufficient buffers to
742 * cover 1/4 of our ram. Beyond the first 64MB allocate additional
743 * buffers to cover 1/10 of our ram over 64MB. When auto-sizing
744 * the buffer cache we limit the eventual kva reservation to
747 * factor represents the 1/4 x ram conversion.
750 int factor = 4 * BKVASIZE / 1024;
753 if (physmem_est > 4096)
754 nbuf += min((physmem_est - 4096) / factor,
756 if (physmem_est > 65536)
757 nbuf += min((physmem_est - 65536) * 2 / (factor * 5),
758 32 * 1024 * 1024 / (factor * 5));
760 if (maxbcache && nbuf > maxbcache / BKVASIZE)
761 nbuf = maxbcache / BKVASIZE;
766 /* XXX Avoid unsigned long overflows later on with maxbufspace. */
767 maxbuf = (LONG_MAX / 3) / BKVASIZE;
770 printf("Warning: nbufs lowered from %d to %ld\n", nbuf,
776 * Ideal allocation size for the transient bio submap is 10%
777 * of the maximal space buffer map. This roughly corresponds
778 * to the amount of the buffer mapped for typical UFS load.
780 * Clip the buffer map to reserve space for the transient
781 * BIOs, if its extent is bigger than 90% (80% on i386) of the
782 * maximum buffer map extent on the platform.
784 * The fall-back to the maxbuf in case of maxbcache unset,
785 * allows to not trim the buffer KVA for the architectures
786 * with ample KVA space.
788 if (bio_transient_maxcnt == 0 && unmapped_buf_allowed) {
789 maxbuf_sz = maxbcache != 0 ? maxbcache : maxbuf * BKVASIZE;
790 buf_sz = (long)nbuf * BKVASIZE;
791 if (buf_sz < maxbuf_sz / TRANSIENT_DENOM *
792 (TRANSIENT_DENOM - 1)) {
794 * There is more KVA than memory. Do not
795 * adjust buffer map size, and assign the rest
796 * of maxbuf to transient map.
798 biotmap_sz = maxbuf_sz - buf_sz;
801 * Buffer map spans all KVA we could afford on
802 * this platform. Give 10% (20% on i386) of
803 * the buffer map to the transient bio map.
805 biotmap_sz = buf_sz / TRANSIENT_DENOM;
806 buf_sz -= biotmap_sz;
808 if (biotmap_sz / INT_MAX > MAXPHYS)
809 bio_transient_maxcnt = INT_MAX;
811 bio_transient_maxcnt = biotmap_sz / MAXPHYS;
813 * Artifically limit to 1024 simultaneous in-flight I/Os
814 * using the transient mapping.
816 if (bio_transient_maxcnt > 1024)
817 bio_transient_maxcnt = 1024;
819 nbuf = buf_sz / BKVASIZE;
823 * swbufs are used as temporary holders for I/O, such as paging I/O.
824 * We have no less then 16 and no more then 256.
826 nswbuf = min(nbuf / 4, 256);
827 TUNABLE_INT_FETCH("kern.nswbuf", &nswbuf);
828 if (nswbuf < NSWBUF_MIN)
832 * Reserve space for the buffer cache buffers
835 v = (caddr_t)(swbuf + nswbuf);
837 v = (caddr_t)(buf + nbuf);
842 /* Initialize the buffer subsystem. Called before use of any buffers. */
849 CTASSERT(MAXBCACHEBUF >= MAXBSIZE);
850 mtx_init(&bqclean, "bufq clean lock", NULL, MTX_DEF);
851 mtx_init(&bqdirty, "bufq dirty lock", NULL, MTX_DEF);
852 mtx_init(&rbreqlock, "runningbufspace lock", NULL, MTX_DEF);
853 rw_init(&nblock, "needsbuffer lock");
854 mtx_init(&bdlock, "buffer daemon lock", NULL, MTX_DEF);
855 mtx_init(&bdirtylock, "dirty buf lock", NULL, MTX_DEF);
857 /* next, make a null set of free lists */
858 for (i = 0; i < BUFFER_QUEUES; i++)
859 TAILQ_INIT(&bufqueues[i]);
861 unmapped_buf = (caddr_t)kva_alloc(MAXPHYS);
863 /* finally, initialize each buffer header and stick on empty q */
864 for (i = 0; i < nbuf; i++) {
866 bzero(bp, sizeof *bp);
867 bp->b_flags = B_INVAL | B_INFREECNT;
868 bp->b_rcred = NOCRED;
869 bp->b_wcred = NOCRED;
870 bp->b_qindex = QUEUE_EMPTY;
872 bp->b_data = bp->b_kvabase = unmapped_buf;
873 LIST_INIT(&bp->b_dep);
875 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_EMPTY], bp, b_freelist);
877 bq_len[QUEUE_EMPTY]++;
882 * maxbufspace is the absolute maximum amount of buffer space we are
883 * allowed to reserve in KVM and in real terms. The absolute maximum
884 * is nominally used by buf_daemon. hibufspace is the nominal maximum
885 * used by most other processes. The differential is required to
886 * ensure that buf_daemon is able to run when other processes might
887 * be blocked waiting for buffer space.
889 * maxbufspace is based on BKVASIZE. Allocating buffers larger then
890 * this may result in KVM fragmentation which is not handled optimally
893 maxbufspace = (long)nbuf * BKVASIZE;
894 hibufspace = lmax(3 * maxbufspace / 4, maxbufspace - MAXBCACHEBUF * 10);
895 lobufspace = hibufspace - MAXBCACHEBUF;
898 * Note: The 16 MiB upper limit for hirunningspace was chosen
899 * arbitrarily and may need further tuning. It corresponds to
900 * 128 outstanding write IO requests (if IO size is 128 KiB),
901 * which fits with many RAID controllers' tagged queuing limits.
902 * The lower 1 MiB limit is the historical upper limit for
905 hirunningspace = lmax(lmin(roundup(hibufspace / 64, MAXBCACHEBUF),
906 16 * 1024 * 1024), 1024 * 1024);
907 lorunningspace = roundup((hirunningspace * 2) / 3, MAXBCACHEBUF);
910 * Limit the amount of malloc memory since it is wired permanently into
911 * the kernel space. Even though this is accounted for in the buffer
912 * allocation, we don't want the malloced region to grow uncontrolled.
913 * The malloc scheme improves memory utilization significantly on average
914 * (small) directories.
916 maxbufmallocspace = hibufspace / 20;
919 * Reduce the chance of a deadlock occuring by limiting the number
920 * of delayed-write dirty buffers we allow to stack up.
922 hidirtybuffers = nbuf / 4 + 20;
923 dirtybufthresh = hidirtybuffers * 9 / 10;
926 * To support extreme low-memory systems, make sure hidirtybuffers cannot
927 * eat up all available buffer space. This occurs when our minimum cannot
928 * be met. We try to size hidirtybuffers to 3/4 our buffer space assuming
929 * BKVASIZE'd buffers.
931 while ((long)hidirtybuffers * BKVASIZE > 3 * hibufspace / 4) {
932 hidirtybuffers >>= 1;
934 lodirtybuffers = hidirtybuffers / 2;
937 * Try to keep the number of free buffers in the specified range,
938 * and give special processes (e.g. like buf_daemon) access to an
941 lofreebuffers = nbuf / 18 + 5;
942 hifreebuffers = 2 * lofreebuffers;
943 numfreebuffers = nbuf;
945 bogus_page = vm_page_alloc(NULL, 0, VM_ALLOC_NOOBJ |
946 VM_ALLOC_NORMAL | VM_ALLOC_WIRED);
951 vfs_buf_check_mapped(struct buf *bp)
954 KASSERT(bp->b_kvabase != unmapped_buf,
955 ("mapped buf: b_kvabase was not updated %p", bp));
956 KASSERT(bp->b_data != unmapped_buf,
957 ("mapped buf: b_data was not updated %p", bp));
958 KASSERT(bp->b_data < unmapped_buf || bp->b_data => unmapped_buf +
959 MAXPHYS, ("b_data + b_offset unmapped %p", bp));
963 vfs_buf_check_unmapped(struct buf *bp)
966 KASSERT(bp->b_data == unmapped_buf,
967 ("unmapped buf: corrupted b_data %p", bp));
970 #define BUF_CHECK_MAPPED(bp) vfs_buf_check_mapped(bp)
971 #define BUF_CHECK_UNMAPPED(bp) vfs_buf_check_unmapped(bp)
973 #define BUF_CHECK_MAPPED(bp) do {} while (0)
974 #define BUF_CHECK_UNMAPPED(bp) do {} while (0)
978 isbufbusy(struct buf *bp)
980 if (((bp->b_flags & (B_INVAL | B_PERSISTENT)) == 0 &&
982 ((bp->b_flags & (B_DELWRI | B_INVAL)) == B_DELWRI))
988 * Shutdown the system cleanly to prepare for reboot, halt, or power off.
991 bufshutdown(int show_busybufs)
993 static int first_buf_printf = 1;
995 int iter, nbusy, pbusy;
1001 * Sync filesystems for shutdown
1003 wdog_kern_pat(WD_LASTVAL);
1004 sys_sync(curthread, NULL);
1007 * With soft updates, some buffers that are
1008 * written will be remarked as dirty until other
1009 * buffers are written.
1011 for (iter = pbusy = 0; iter < 20; iter++) {
1013 for (bp = &buf[nbuf]; --bp >= buf; )
1017 if (first_buf_printf)
1018 printf("All buffers synced.");
1021 if (first_buf_printf) {
1022 printf("Syncing disks, buffers remaining... ");
1023 first_buf_printf = 0;
1025 printf("%d ", nbusy);
1030 wdog_kern_pat(WD_LASTVAL);
1031 sys_sync(curthread, NULL);
1035 * Drop Giant and spin for a while to allow
1036 * interrupt threads to run.
1039 DELAY(50000 * iter);
1043 * Drop Giant and context switch several times to
1044 * allow interrupt threads to run.
1047 for (subiter = 0; subiter < 50 * iter; subiter++) {
1048 thread_lock(curthread);
1049 mi_switch(SW_VOL, NULL);
1050 thread_unlock(curthread);
1058 * Count only busy local buffers to prevent forcing
1059 * a fsck if we're just a client of a wedged NFS server
1062 for (bp = &buf[nbuf]; --bp >= buf; ) {
1063 if (isbufbusy(bp)) {
1065 /* XXX: This is bogus. We should probably have a BO_REMOTE flag instead */
1066 if (bp->b_dev == NULL) {
1067 TAILQ_REMOVE(&mountlist,
1068 bp->b_vp->v_mount, mnt_list);
1073 if (show_busybufs > 0) {
1075 "%d: buf:%p, vnode:%p, flags:%0x, blkno:%jd, lblkno:%jd, buflock:",
1076 nbusy, bp, bp->b_vp, bp->b_flags,
1077 (intmax_t)bp->b_blkno,
1078 (intmax_t)bp->b_lblkno);
1079 BUF_LOCKPRINTINFO(bp);
1080 if (show_busybufs > 1)
1088 * Failed to sync all blocks. Indicate this and don't
1089 * unmount filesystems (thus forcing an fsck on reboot).
1091 printf("Giving up on %d buffers\n", nbusy);
1092 DELAY(5000000); /* 5 seconds */
1094 if (!first_buf_printf)
1095 printf("Final sync complete\n");
1097 * Unmount filesystems
1103 DELAY(100000); /* wait for console output to finish */
1107 bpmap_qenter(struct buf *bp)
1110 BUF_CHECK_MAPPED(bp);
1113 * bp->b_data is relative to bp->b_offset, but
1114 * bp->b_offset may be offset into the first page.
1116 bp->b_data = (caddr_t)trunc_page((vm_offset_t)bp->b_data);
1117 pmap_qenter((vm_offset_t)bp->b_data, bp->b_pages, bp->b_npages);
1118 bp->b_data = (caddr_t)((vm_offset_t)bp->b_data |
1119 (vm_offset_t)(bp->b_offset & PAGE_MASK));
1125 * Insert the buffer into the appropriate free list.
1128 binsfree(struct buf *bp, int qindex)
1130 struct mtx *olock, *nlock;
1132 BUF_ASSERT_XLOCKED(bp);
1134 nlock = bqlock(qindex);
1135 /* Handle delayed bremfree() processing. */
1136 if (bp->b_flags & B_REMFREE) {
1137 olock = bqlock(bp->b_qindex);
1140 if (olock != nlock) {
1147 if (bp->b_qindex != QUEUE_NONE)
1148 panic("binsfree: free buffer onto another queue???");
1150 bp->b_qindex = qindex;
1151 if (bp->b_flags & B_AGE)
1152 TAILQ_INSERT_HEAD(&bufqueues[bp->b_qindex], bp, b_freelist);
1154 TAILQ_INSERT_TAIL(&bufqueues[bp->b_qindex], bp, b_freelist);
1156 bq_len[bp->b_qindex]++;
1161 * Something we can maybe free or reuse.
1163 if (bp->b_bufsize && !(bp->b_flags & B_DELWRI))
1166 if ((bp->b_flags & B_INVAL) || !(bp->b_flags & B_DELWRI))
1173 * Mark the buffer for removal from the appropriate free list.
1177 bremfree(struct buf *bp)
1180 CTR3(KTR_BUF, "bremfree(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
1181 KASSERT((bp->b_flags & B_REMFREE) == 0,
1182 ("bremfree: buffer %p already marked for delayed removal.", bp));
1183 KASSERT(bp->b_qindex != QUEUE_NONE,
1184 ("bremfree: buffer %p not on a queue.", bp));
1185 BUF_ASSERT_XLOCKED(bp);
1187 bp->b_flags |= B_REMFREE;
1194 * Force an immediate removal from a free list. Used only in nfs when
1195 * it abuses the b_freelist pointer.
1198 bremfreef(struct buf *bp)
1202 qlock = bqlock(bp->b_qindex);
1211 * Removes a buffer from the free list, must be called with the
1212 * correct qlock held.
1215 bremfreel(struct buf *bp)
1218 CTR3(KTR_BUF, "bremfreel(%p) vp %p flags %X",
1219 bp, bp->b_vp, bp->b_flags);
1220 KASSERT(bp->b_qindex != QUEUE_NONE,
1221 ("bremfreel: buffer %p not on a queue.", bp));
1222 BUF_ASSERT_XLOCKED(bp);
1223 mtx_assert(bqlock(bp->b_qindex), MA_OWNED);
1225 TAILQ_REMOVE(&bufqueues[bp->b_qindex], bp, b_freelist);
1227 KASSERT(bq_len[bp->b_qindex] >= 1, ("queue %d underflow",
1229 bq_len[bp->b_qindex]--;
1231 bp->b_qindex = QUEUE_NONE;
1233 * If this was a delayed bremfree() we only need to remove the buffer
1234 * from the queue and return the stats are already done.
1236 if (bp->b_flags & B_REMFREE) {
1237 bp->b_flags &= ~B_REMFREE;
1246 * Free the kva allocation for a buffer.
1250 bufkvafree(struct buf *bp)
1254 if (bp->b_kvasize == 0) {
1255 KASSERT(bp->b_kvabase == unmapped_buf &&
1256 bp->b_data == unmapped_buf,
1257 ("Leaked KVA space on %p", bp));
1258 } else if (buf_mapped(bp))
1259 BUF_CHECK_MAPPED(bp);
1261 BUF_CHECK_UNMAPPED(bp);
1263 if (bp->b_kvasize == 0)
1266 vmem_free(buffer_arena, (vm_offset_t)bp->b_kvabase, bp->b_kvasize);
1267 atomic_subtract_long(&bufkvaspace, bp->b_kvasize);
1268 atomic_add_int(&buffreekvacnt, 1);
1269 bp->b_data = bp->b_kvabase = unmapped_buf;
1276 * Allocate the buffer KVA and set b_kvasize and b_kvabase.
1279 bufkvaalloc(struct buf *bp, int maxsize, int gbflags)
1284 KASSERT((gbflags & GB_UNMAPPED) == 0 || (gbflags & GB_KVAALLOC) != 0,
1285 ("Invalid gbflags 0x%x in %s", gbflags, __func__));
1290 error = vmem_alloc(buffer_arena, maxsize, M_BESTFIT | M_NOWAIT, &addr);
1293 * Buffer map is too fragmented. Request the caller
1294 * to defragment the map.
1296 atomic_add_int(&bufdefragcnt, 1);
1299 bp->b_kvabase = (caddr_t)addr;
1300 bp->b_kvasize = maxsize;
1301 atomic_add_long(&bufkvaspace, bp->b_kvasize);
1302 if ((gbflags & GB_UNMAPPED) != 0) {
1303 bp->b_data = unmapped_buf;
1304 BUF_CHECK_UNMAPPED(bp);
1306 bp->b_data = bp->b_kvabase;
1307 BUF_CHECK_MAPPED(bp);
1313 * Attempt to initiate asynchronous I/O on read-ahead blocks. We must
1314 * clear BIO_ERROR and B_INVAL prior to initiating I/O . If B_CACHE is set,
1315 * the buffer is valid and we do not have to do anything.
1318 breada(struct vnode * vp, daddr_t * rablkno, int * rabsize,
1319 int cnt, struct ucred * cred)
1324 for (i = 0; i < cnt; i++, rablkno++, rabsize++) {
1325 if (inmem(vp, *rablkno))
1327 rabp = getblk(vp, *rablkno, *rabsize, 0, 0, 0);
1329 if ((rabp->b_flags & B_CACHE) == 0) {
1330 if (!TD_IS_IDLETHREAD(curthread))
1331 curthread->td_ru.ru_inblock++;
1332 rabp->b_flags |= B_ASYNC;
1333 rabp->b_flags &= ~B_INVAL;
1334 rabp->b_ioflags &= ~BIO_ERROR;
1335 rabp->b_iocmd = BIO_READ;
1336 if (rabp->b_rcred == NOCRED && cred != NOCRED)
1337 rabp->b_rcred = crhold(cred);
1338 vfs_busy_pages(rabp, 0);
1340 rabp->b_iooffset = dbtob(rabp->b_blkno);
1349 * Entry point for bread() and breadn() via #defines in sys/buf.h.
1351 * Get a buffer with the specified data. Look in the cache first. We
1352 * must clear BIO_ERROR and B_INVAL prior to initiating I/O. If B_CACHE
1353 * is set, the buffer is valid and we do not have to do anything, see
1354 * getblk(). Also starts asynchronous I/O on read-ahead blocks.
1357 breadn_flags(struct vnode *vp, daddr_t blkno, int size, daddr_t *rablkno,
1358 int *rabsize, int cnt, struct ucred *cred, int flags, struct buf **bpp)
1361 int rv = 0, readwait = 0;
1363 CTR3(KTR_BUF, "breadn(%p, %jd, %d)", vp, blkno, size);
1365 * Can only return NULL if GB_LOCK_NOWAIT flag is specified.
1367 *bpp = bp = getblk(vp, blkno, size, 0, 0, flags);
1371 /* if not found in cache, do some I/O */
1372 if ((bp->b_flags & B_CACHE) == 0) {
1373 if (!TD_IS_IDLETHREAD(curthread))
1374 curthread->td_ru.ru_inblock++;
1375 bp->b_iocmd = BIO_READ;
1376 bp->b_flags &= ~B_INVAL;
1377 bp->b_ioflags &= ~BIO_ERROR;
1378 if (bp->b_rcred == NOCRED && cred != NOCRED)
1379 bp->b_rcred = crhold(cred);
1380 vfs_busy_pages(bp, 0);
1381 bp->b_iooffset = dbtob(bp->b_blkno);
1386 breada(vp, rablkno, rabsize, cnt, cred);
1395 * Write, release buffer on completion. (Done by iodone
1396 * if async). Do not bother writing anything if the buffer
1399 * Note that we set B_CACHE here, indicating that buffer is
1400 * fully valid and thus cacheable. This is true even of NFS
1401 * now so we set it generally. This could be set either here
1402 * or in biodone() since the I/O is synchronous. We put it
1406 bufwrite(struct buf *bp)
1413 CTR3(KTR_BUF, "bufwrite(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
1414 if ((bp->b_bufobj->bo_flag & BO_DEAD) != 0) {
1415 bp->b_flags |= B_INVAL | B_RELBUF;
1416 bp->b_flags &= ~B_CACHE;
1420 if (bp->b_flags & B_INVAL) {
1425 if (bp->b_flags & B_BARRIER)
1428 oldflags = bp->b_flags;
1430 BUF_ASSERT_HELD(bp);
1432 if (bp->b_pin_count > 0)
1435 KASSERT(!(bp->b_vflags & BV_BKGRDINPROG),
1436 ("FFS background buffer should not get here %p", bp));
1440 vp_md = vp->v_vflag & VV_MD;
1445 * Mark the buffer clean. Increment the bufobj write count
1446 * before bundirty() call, to prevent other thread from seeing
1447 * empty dirty list and zero counter for writes in progress,
1448 * falsely indicating that the bufobj is clean.
1450 bufobj_wref(bp->b_bufobj);
1453 bp->b_flags &= ~B_DONE;
1454 bp->b_ioflags &= ~BIO_ERROR;
1455 bp->b_flags |= B_CACHE;
1456 bp->b_iocmd = BIO_WRITE;
1458 vfs_busy_pages(bp, 1);
1461 * Normal bwrites pipeline writes
1463 bp->b_runningbufspace = bp->b_bufsize;
1464 space = atomic_fetchadd_long(&runningbufspace, bp->b_runningbufspace);
1466 if (!TD_IS_IDLETHREAD(curthread))
1467 curthread->td_ru.ru_oublock++;
1468 if (oldflags & B_ASYNC)
1470 bp->b_iooffset = dbtob(bp->b_blkno);
1473 if ((oldflags & B_ASYNC) == 0) {
1474 int rtval = bufwait(bp);
1477 } else if (space > hirunningspace) {
1479 * don't allow the async write to saturate the I/O
1480 * system. We will not deadlock here because
1481 * we are blocking waiting for I/O that is already in-progress
1482 * to complete. We do not block here if it is the update
1483 * or syncer daemon trying to clean up as that can lead
1486 if ((curthread->td_pflags & TDP_NORUNNINGBUF) == 0 && !vp_md)
1487 waitrunningbufspace();
1494 bufbdflush(struct bufobj *bo, struct buf *bp)
1498 if (bo->bo_dirty.bv_cnt > dirtybufthresh + 10) {
1499 (void) VOP_FSYNC(bp->b_vp, MNT_NOWAIT, curthread);
1501 } else if (bo->bo_dirty.bv_cnt > dirtybufthresh) {
1504 * Try to find a buffer to flush.
1506 TAILQ_FOREACH(nbp, &bo->bo_dirty.bv_hd, b_bobufs) {
1507 if ((nbp->b_vflags & BV_BKGRDINPROG) ||
1509 LK_EXCLUSIVE | LK_NOWAIT, NULL))
1512 panic("bdwrite: found ourselves");
1514 /* Don't countdeps with the bo lock held. */
1515 if (buf_countdeps(nbp, 0)) {
1520 if (nbp->b_flags & B_CLUSTEROK) {
1521 vfs_bio_awrite(nbp);
1526 dirtybufferflushes++;
1535 * Delayed write. (Buffer is marked dirty). Do not bother writing
1536 * anything if the buffer is marked invalid.
1538 * Note that since the buffer must be completely valid, we can safely
1539 * set B_CACHE. In fact, we have to set B_CACHE here rather then in
1540 * biodone() in order to prevent getblk from writing the buffer
1541 * out synchronously.
1544 bdwrite(struct buf *bp)
1546 struct thread *td = curthread;
1550 CTR3(KTR_BUF, "bdwrite(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
1551 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp));
1552 KASSERT((bp->b_flags & B_BARRIER) == 0,
1553 ("Barrier request in delayed write %p", bp));
1554 BUF_ASSERT_HELD(bp);
1556 if (bp->b_flags & B_INVAL) {
1562 * If we have too many dirty buffers, don't create any more.
1563 * If we are wildly over our limit, then force a complete
1564 * cleanup. Otherwise, just keep the situation from getting
1565 * out of control. Note that we have to avoid a recursive
1566 * disaster and not try to clean up after our own cleanup!
1570 if ((td->td_pflags & (TDP_COWINPROGRESS|TDP_INBDFLUSH)) == 0) {
1571 td->td_pflags |= TDP_INBDFLUSH;
1573 td->td_pflags &= ~TDP_INBDFLUSH;
1579 * Set B_CACHE, indicating that the buffer is fully valid. This is
1580 * true even of NFS now.
1582 bp->b_flags |= B_CACHE;
1585 * This bmap keeps the system from needing to do the bmap later,
1586 * perhaps when the system is attempting to do a sync. Since it
1587 * is likely that the indirect block -- or whatever other datastructure
1588 * that the filesystem needs is still in memory now, it is a good
1589 * thing to do this. Note also, that if the pageout daemon is
1590 * requesting a sync -- there might not be enough memory to do
1591 * the bmap then... So, this is important to do.
1593 if (vp->v_type != VCHR && bp->b_lblkno == bp->b_blkno) {
1594 VOP_BMAP(vp, bp->b_lblkno, NULL, &bp->b_blkno, NULL, NULL);
1598 * Set the *dirty* buffer range based upon the VM system dirty
1601 * Mark the buffer pages as clean. We need to do this here to
1602 * satisfy the vnode_pager and the pageout daemon, so that it
1603 * thinks that the pages have been "cleaned". Note that since
1604 * the pages are in a delayed write buffer -- the VFS layer
1605 * "will" see that the pages get written out on the next sync,
1606 * or perhaps the cluster will be completed.
1608 vfs_clean_pages_dirty_buf(bp);
1612 * note: we cannot initiate I/O from a bdwrite even if we wanted to,
1613 * due to the softdep code.
1620 * Turn buffer into delayed write request. We must clear BIO_READ and
1621 * B_RELBUF, and we must set B_DELWRI. We reassign the buffer to
1622 * itself to properly update it in the dirty/clean lists. We mark it
1623 * B_DONE to ensure that any asynchronization of the buffer properly
1624 * clears B_DONE ( else a panic will occur later ).
1626 * bdirty() is kinda like bdwrite() - we have to clear B_INVAL which
1627 * might have been set pre-getblk(). Unlike bwrite/bdwrite, bdirty()
1628 * should only be called if the buffer is known-good.
1630 * Since the buffer is not on a queue, we do not update the numfreebuffers
1633 * The buffer must be on QUEUE_NONE.
1636 bdirty(struct buf *bp)
1639 CTR3(KTR_BUF, "bdirty(%p) vp %p flags %X",
1640 bp, bp->b_vp, bp->b_flags);
1641 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp));
1642 KASSERT(bp->b_flags & B_REMFREE || bp->b_qindex == QUEUE_NONE,
1643 ("bdirty: buffer %p still on queue %d", bp, bp->b_qindex));
1644 BUF_ASSERT_HELD(bp);
1645 bp->b_flags &= ~(B_RELBUF);
1646 bp->b_iocmd = BIO_WRITE;
1648 if ((bp->b_flags & B_DELWRI) == 0) {
1649 bp->b_flags |= /* XXX B_DONE | */ B_DELWRI;
1658 * Clear B_DELWRI for buffer.
1660 * Since the buffer is not on a queue, we do not update the numfreebuffers
1663 * The buffer must be on QUEUE_NONE.
1667 bundirty(struct buf *bp)
1670 CTR3(KTR_BUF, "bundirty(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
1671 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp));
1672 KASSERT(bp->b_flags & B_REMFREE || bp->b_qindex == QUEUE_NONE,
1673 ("bundirty: buffer %p still on queue %d", bp, bp->b_qindex));
1674 BUF_ASSERT_HELD(bp);
1676 if (bp->b_flags & B_DELWRI) {
1677 bp->b_flags &= ~B_DELWRI;
1682 * Since it is now being written, we can clear its deferred write flag.
1684 bp->b_flags &= ~B_DEFERRED;
1690 * Asynchronous write. Start output on a buffer, but do not wait for
1691 * it to complete. The buffer is released when the output completes.
1693 * bwrite() ( or the VOP routine anyway ) is responsible for handling
1694 * B_INVAL buffers. Not us.
1697 bawrite(struct buf *bp)
1700 bp->b_flags |= B_ASYNC;
1707 * Asynchronous barrier write. Start output on a buffer, but do not
1708 * wait for it to complete. Place a write barrier after this write so
1709 * that this buffer and all buffers written before it are committed to
1710 * the disk before any buffers written after this write are committed
1711 * to the disk. The buffer is released when the output completes.
1714 babarrierwrite(struct buf *bp)
1717 bp->b_flags |= B_ASYNC | B_BARRIER;
1724 * Synchronous barrier write. Start output on a buffer and wait for
1725 * it to complete. Place a write barrier after this write so that
1726 * this buffer and all buffers written before it are committed to
1727 * the disk before any buffers written after this write are committed
1728 * to the disk. The buffer is released when the output completes.
1731 bbarrierwrite(struct buf *bp)
1734 bp->b_flags |= B_BARRIER;
1735 return (bwrite(bp));
1741 * Called prior to the locking of any vnodes when we are expecting to
1742 * write. We do not want to starve the buffer cache with too many
1743 * dirty buffers so we block here. By blocking prior to the locking
1744 * of any vnodes we attempt to avoid the situation where a locked vnode
1745 * prevents the various system daemons from flushing related buffers.
1751 if (numdirtybuffers >= hidirtybuffers) {
1752 mtx_lock(&bdirtylock);
1753 while (numdirtybuffers >= hidirtybuffers) {
1755 msleep(&bdirtywait, &bdirtylock, (PRIBIO + 4),
1758 mtx_unlock(&bdirtylock);
1763 * Return true if we have too many dirty buffers.
1766 buf_dirty_count_severe(void)
1769 return(numdirtybuffers >= hidirtybuffers);
1775 * Release a busy buffer and, if requested, free its resources. The
1776 * buffer will be stashed in the appropriate bufqueue[] allowing it
1777 * to be accessed later as a cache entity or reused for other purposes.
1780 brelse(struct buf *bp)
1784 CTR3(KTR_BUF, "brelse(%p) vp %p flags %X",
1785 bp, bp->b_vp, bp->b_flags);
1786 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)),
1787 ("brelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp));
1789 if (BUF_LOCKRECURSED(bp)) {
1791 * Do not process, in particular, do not handle the
1792 * B_INVAL/B_RELBUF and do not release to free list.
1798 if (bp->b_flags & B_MANAGED) {
1803 if ((bp->b_vflags & (BV_BKGRDINPROG | BV_BKGRDERR)) == BV_BKGRDERR) {
1804 BO_LOCK(bp->b_bufobj);
1805 bp->b_vflags &= ~BV_BKGRDERR;
1806 BO_UNLOCK(bp->b_bufobj);
1809 if (bp->b_iocmd == BIO_WRITE && (bp->b_ioflags & BIO_ERROR) &&
1810 bp->b_error == EIO && !(bp->b_flags & B_INVAL)) {
1812 * Failed write, redirty. Must clear BIO_ERROR to prevent
1813 * pages from being scrapped. If the error is anything
1814 * other than an I/O error (EIO), assume that retrying
1817 bp->b_ioflags &= ~BIO_ERROR;
1819 } else if ((bp->b_flags & (B_NOCACHE | B_INVAL)) ||
1820 (bp->b_ioflags & BIO_ERROR) || (bp->b_bufsize <= 0)) {
1822 * Either a failed I/O or we were asked to free or not
1825 bp->b_flags |= B_INVAL;
1826 if (!LIST_EMPTY(&bp->b_dep))
1828 if (bp->b_flags & B_DELWRI)
1830 bp->b_flags &= ~(B_DELWRI | B_CACHE);
1831 if ((bp->b_flags & B_VMIO) == 0) {
1840 * We must clear B_RELBUF if B_DELWRI is set. If vfs_vmio_release()
1841 * is called with B_DELWRI set, the underlying pages may wind up
1842 * getting freed causing a previous write (bdwrite()) to get 'lost'
1843 * because pages associated with a B_DELWRI bp are marked clean.
1845 * We still allow the B_INVAL case to call vfs_vmio_release(), even
1846 * if B_DELWRI is set.
1848 if (bp->b_flags & B_DELWRI)
1849 bp->b_flags &= ~B_RELBUF;
1852 * VMIO buffer rundown. It is not very necessary to keep a VMIO buffer
1853 * constituted, not even NFS buffers now. Two flags effect this. If
1854 * B_INVAL, the struct buf is invalidated but the VM object is kept
1855 * around ( i.e. so it is trivial to reconstitute the buffer later ).
1857 * If BIO_ERROR or B_NOCACHE is set, pages in the VM object will be
1858 * invalidated. BIO_ERROR cannot be set for a failed write unless the
1859 * buffer is also B_INVAL because it hits the re-dirtying code above.
1861 * Normally we can do this whether a buffer is B_DELWRI or not. If
1862 * the buffer is an NFS buffer, it is tracking piecemeal writes or
1863 * the commit state and we cannot afford to lose the buffer. If the
1864 * buffer has a background write in progress, we need to keep it
1865 * around to prevent it from being reconstituted and starting a second
1868 if ((bp->b_flags & B_VMIO)
1869 && !(bp->b_vp->v_mount != NULL &&
1870 (bp->b_vp->v_mount->mnt_vfc->vfc_flags & VFCF_NETWORK) != 0 &&
1871 !vn_isdisk(bp->b_vp, NULL) &&
1872 (bp->b_flags & B_DELWRI))
1881 obj = bp->b_bufobj->bo_object;
1884 * Get the base offset and length of the buffer. Note that
1885 * in the VMIO case if the buffer block size is not
1886 * page-aligned then b_data pointer may not be page-aligned.
1887 * But our b_pages[] array *IS* page aligned.
1889 * block sizes less then DEV_BSIZE (usually 512) are not
1890 * supported due to the page granularity bits (m->valid,
1891 * m->dirty, etc...).
1893 * See man buf(9) for more information
1895 resid = bp->b_bufsize;
1896 foff = bp->b_offset;
1897 for (i = 0; i < bp->b_npages; i++) {
1903 * If we hit a bogus page, fixup *all* the bogus pages
1906 if (m == bogus_page) {
1907 poff = OFF_TO_IDX(bp->b_offset);
1910 VM_OBJECT_RLOCK(obj);
1911 for (j = i; j < bp->b_npages; j++) {
1913 mtmp = bp->b_pages[j];
1914 if (mtmp == bogus_page) {
1915 mtmp = vm_page_lookup(obj, poff + j);
1917 panic("brelse: page missing\n");
1919 bp->b_pages[j] = mtmp;
1922 VM_OBJECT_RUNLOCK(obj);
1924 if ((bp->b_flags & B_INVAL) == 0 &&
1926 BUF_CHECK_MAPPED(bp);
1928 trunc_page((vm_offset_t)bp->b_data),
1929 bp->b_pages, bp->b_npages);
1933 if ((bp->b_flags & B_NOCACHE) ||
1934 (bp->b_ioflags & BIO_ERROR &&
1935 bp->b_iocmd == BIO_READ)) {
1936 int poffset = foff & PAGE_MASK;
1937 int presid = resid > (PAGE_SIZE - poffset) ?
1938 (PAGE_SIZE - poffset) : resid;
1940 KASSERT(presid >= 0, ("brelse: extra page"));
1941 VM_OBJECT_WLOCK(obj);
1942 while (vm_page_xbusied(m)) {
1944 VM_OBJECT_WUNLOCK(obj);
1945 vm_page_busy_sleep(m, "mbncsh");
1946 VM_OBJECT_WLOCK(obj);
1948 if (pmap_page_wired_mappings(m) == 0)
1949 vm_page_set_invalid(m, poffset, presid);
1950 VM_OBJECT_WUNLOCK(obj);
1952 printf("avoided corruption bug in bogus_page/brelse code\n");
1954 resid -= PAGE_SIZE - (foff & PAGE_MASK);
1955 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK;
1957 if (bp->b_flags & (B_INVAL | B_RELBUF))
1958 vfs_vmio_release(bp);
1960 } else if (bp->b_flags & B_VMIO) {
1962 if (bp->b_flags & (B_INVAL | B_RELBUF)) {
1963 vfs_vmio_release(bp);
1966 } else if ((bp->b_flags & (B_INVAL | B_RELBUF)) != 0) {
1967 if (bp->b_bufsize != 0)
1969 if (bp->b_vp != NULL)
1974 * If the buffer has junk contents signal it and eventually
1975 * clean up B_DELWRI and diassociate the vnode so that gbincore()
1978 if (bp->b_bufsize == 0 || (bp->b_ioflags & BIO_ERROR) != 0 ||
1979 (bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF)) != 0)
1980 bp->b_flags |= B_INVAL;
1981 if (bp->b_flags & B_INVAL) {
1982 if (bp->b_flags & B_DELWRI)
1988 /* buffers with no memory */
1989 if (bp->b_bufsize == 0) {
1990 bp->b_xflags &= ~(BX_BKGRDWRITE | BX_ALTDATA);
1991 if (bp->b_vflags & BV_BKGRDINPROG)
1992 panic("losing buffer 1");
1994 qindex = QUEUE_EMPTY;
1995 bp->b_flags |= B_AGE;
1996 /* buffers with junk contents */
1997 } else if (bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF) ||
1998 (bp->b_ioflags & BIO_ERROR)) {
1999 bp->b_xflags &= ~(BX_BKGRDWRITE | BX_ALTDATA);
2000 if (bp->b_vflags & BV_BKGRDINPROG)
2001 panic("losing buffer 2");
2002 qindex = QUEUE_CLEAN;
2003 bp->b_flags |= B_AGE;
2004 /* remaining buffers */
2005 } else if (bp->b_flags & B_DELWRI)
2006 qindex = QUEUE_DIRTY;
2008 qindex = QUEUE_CLEAN;
2010 binsfree(bp, qindex);
2012 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF | B_DIRECT);
2013 if ((bp->b_flags & B_DELWRI) == 0 && (bp->b_xflags & BX_VNDIRTY))
2014 panic("brelse: not dirty");
2020 * Release a buffer back to the appropriate queue but do not try to free
2021 * it. The buffer is expected to be used again soon.
2023 * bqrelse() is used by bdwrite() to requeue a delayed write, and used by
2024 * biodone() to requeue an async I/O on completion. It is also used when
2025 * known good buffers need to be requeued but we think we may need the data
2028 * XXX we should be able to leave the B_RELBUF hint set on completion.
2031 bqrelse(struct buf *bp)
2035 CTR3(KTR_BUF, "bqrelse(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
2036 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)),
2037 ("bqrelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp));
2039 if (BUF_LOCKRECURSED(bp)) {
2040 /* do not release to free list */
2044 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF);
2046 if (bp->b_flags & B_MANAGED) {
2047 if (bp->b_flags & B_REMFREE)
2052 /* buffers with stale but valid contents */
2053 if ((bp->b_flags & B_DELWRI) != 0 || (bp->b_vflags & (BV_BKGRDINPROG |
2054 BV_BKGRDERR)) == BV_BKGRDERR) {
2055 BO_LOCK(bp->b_bufobj);
2056 bp->b_vflags &= ~BV_BKGRDERR;
2057 BO_UNLOCK(bp->b_bufobj);
2058 qindex = QUEUE_DIRTY;
2060 if ((bp->b_flags & B_DELWRI) == 0 &&
2061 (bp->b_xflags & BX_VNDIRTY))
2062 panic("bqrelse: not dirty");
2063 qindex = QUEUE_CLEAN;
2065 binsfree(bp, qindex);
2072 /* Give pages used by the bp back to the VM system (where possible) */
2074 vfs_vmio_release(struct buf *bp)
2080 if (buf_mapped(bp)) {
2081 BUF_CHECK_MAPPED(bp);
2082 pmap_qremove(trunc_page((vm_offset_t)bp->b_data), bp->b_npages);
2084 BUF_CHECK_UNMAPPED(bp);
2085 obj = bp->b_bufobj->bo_object;
2087 VM_OBJECT_WLOCK(obj);
2088 for (i = 0; i < bp->b_npages; i++) {
2090 bp->b_pages[i] = NULL;
2092 * In order to keep page LRU ordering consistent, put
2093 * everything on the inactive queue.
2096 vm_page_unwire(m, PQ_INACTIVE);
2099 * Might as well free the page if we can and it has
2100 * no valid data. We also free the page if the
2101 * buffer was used for direct I/O
2103 if ((bp->b_flags & B_ASYNC) == 0 && !m->valid) {
2104 if (m->wire_count == 0 && !vm_page_busied(m))
2106 } else if (bp->b_flags & B_DIRECT)
2107 vm_page_try_to_free(m);
2111 VM_OBJECT_WUNLOCK(obj);
2114 bufspaceadjust(bp, 0);
2116 bp->b_flags &= ~B_VMIO;
2122 * Check to see if a block at a particular lbn is available for a clustered
2126 vfs_bio_clcheck(struct vnode *vp, int size, daddr_t lblkno, daddr_t blkno)
2133 /* If the buf isn't in core skip it */
2134 if ((bpa = gbincore(&vp->v_bufobj, lblkno)) == NULL)
2137 /* If the buf is busy we don't want to wait for it */
2138 if (BUF_LOCK(bpa, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0)
2141 /* Only cluster with valid clusterable delayed write buffers */
2142 if ((bpa->b_flags & (B_DELWRI | B_CLUSTEROK | B_INVAL)) !=
2143 (B_DELWRI | B_CLUSTEROK))
2146 if (bpa->b_bufsize != size)
2150 * Check to see if it is in the expected place on disk and that the
2151 * block has been mapped.
2153 if ((bpa->b_blkno != bpa->b_lblkno) && (bpa->b_blkno == blkno))
2163 * Implement clustered async writes for clearing out B_DELWRI buffers.
2164 * This is much better then the old way of writing only one buffer at
2165 * a time. Note that we may not be presented with the buffers in the
2166 * correct order, so we search for the cluster in both directions.
2169 vfs_bio_awrite(struct buf *bp)
2174 daddr_t lblkno = bp->b_lblkno;
2175 struct vnode *vp = bp->b_vp;
2183 gbflags = (bp->b_data == unmapped_buf) ? GB_UNMAPPED : 0;
2185 * right now we support clustered writing only to regular files. If
2186 * we find a clusterable block we could be in the middle of a cluster
2187 * rather then at the beginning.
2189 if ((vp->v_type == VREG) &&
2190 (vp->v_mount != 0) && /* Only on nodes that have the size info */
2191 (bp->b_flags & (B_CLUSTEROK | B_INVAL)) == B_CLUSTEROK) {
2193 size = vp->v_mount->mnt_stat.f_iosize;
2194 maxcl = MAXPHYS / size;
2197 for (i = 1; i < maxcl; i++)
2198 if (vfs_bio_clcheck(vp, size, lblkno + i,
2199 bp->b_blkno + ((i * size) >> DEV_BSHIFT)) == 0)
2202 for (j = 1; i + j <= maxcl && j <= lblkno; j++)
2203 if (vfs_bio_clcheck(vp, size, lblkno - j,
2204 bp->b_blkno - ((j * size) >> DEV_BSHIFT)) == 0)
2210 * this is a possible cluster write
2214 nwritten = cluster_wbuild(vp, size, lblkno - j, ncl,
2220 bp->b_flags |= B_ASYNC;
2222 * default (old) behavior, writing out only one block
2224 * XXX returns b_bufsize instead of b_bcount for nwritten?
2226 nwritten = bp->b_bufsize;
2233 * Ask the bufdaemon for help, or act as bufdaemon itself, when a
2234 * locked vnode is supplied.
2237 getnewbuf_bufd_help(struct vnode *vp, int gbflags, int slpflag, int slptimeo,
2242 int error, fl, flags, norunbuf;
2244 mtx_assert(&bqclean, MA_OWNED);
2247 flags = VFS_BIO_NEED_BUFSPACE;
2249 } else if (bufspace >= hibufspace) {
2251 flags = VFS_BIO_NEED_BUFSPACE;
2254 flags = VFS_BIO_NEED_ANY;
2256 atomic_set_int(&needsbuffer, flags);
2257 mtx_unlock(&bqclean);
2259 bd_speedup(); /* heeeelp */
2260 if ((gbflags & GB_NOWAIT_BD) != 0)
2265 while ((needsbuffer & flags) != 0) {
2266 if (vp != NULL && vp->v_type != VCHR &&
2267 (td->td_pflags & TDP_BUFNEED) == 0) {
2268 rw_wunlock(&nblock);
2270 * getblk() is called with a vnode locked, and
2271 * some majority of the dirty buffers may as
2272 * well belong to the vnode. Flushing the
2273 * buffers there would make a progress that
2274 * cannot be achieved by the buf_daemon, that
2275 * cannot lock the vnode.
2277 norunbuf = ~(TDP_BUFNEED | TDP_NORUNNINGBUF) |
2278 (td->td_pflags & TDP_NORUNNINGBUF);
2281 * Play bufdaemon. The getnewbuf() function
2282 * may be called while the thread owns lock
2283 * for another dirty buffer for the same
2284 * vnode, which makes it impossible to use
2285 * VOP_FSYNC() there, due to the buffer lock
2288 td->td_pflags |= TDP_BUFNEED | TDP_NORUNNINGBUF;
2289 fl = buf_flush(vp, flushbufqtarget);
2290 td->td_pflags &= norunbuf;
2294 if ((needsbuffer & flags) == 0)
2297 error = rw_sleep(__DEVOLATILE(void *, &needsbuffer), &nblock,
2298 (PRIBIO + 4) | slpflag, waitmsg, slptimeo);
2302 rw_wunlock(&nblock);
2306 getnewbuf_reuse_bp(struct buf *bp, int qindex)
2309 CTR6(KTR_BUF, "getnewbuf(%p) vp %p flags %X kvasize %d bufsize %d "
2310 "queue %d (recycling)", bp, bp->b_vp, bp->b_flags,
2311 bp->b_kvasize, bp->b_bufsize, qindex);
2312 mtx_assert(&bqclean, MA_NOTOWNED);
2315 * Note: we no longer distinguish between VMIO and non-VMIO
2318 KASSERT((bp->b_flags & B_DELWRI) == 0,
2319 ("delwri buffer %p found in queue %d", bp, qindex));
2321 if (qindex == QUEUE_CLEAN) {
2322 if (bp->b_flags & B_VMIO) {
2323 bp->b_flags &= ~B_ASYNC;
2324 vfs_vmio_release(bp);
2326 if (bp->b_vp != NULL)
2331 * Get the rest of the buffer freed up. b_kva* is still valid
2332 * after this operation.
2335 if (bp->b_rcred != NOCRED) {
2336 crfree(bp->b_rcred);
2337 bp->b_rcred = NOCRED;
2339 if (bp->b_wcred != NOCRED) {
2340 crfree(bp->b_wcred);
2341 bp->b_wcred = NOCRED;
2343 if (!LIST_EMPTY(&bp->b_dep))
2345 if (bp->b_vflags & BV_BKGRDINPROG)
2346 panic("losing buffer 3");
2347 KASSERT(bp->b_vp == NULL, ("bp: %p still has vnode %p. qindex: %d",
2348 bp, bp->b_vp, qindex));
2349 KASSERT((bp->b_xflags & (BX_VNCLEAN|BX_VNDIRTY)) == 0,
2350 ("bp: %p still on a buffer list. xflags %X", bp, bp->b_xflags));
2358 KASSERT((bp->b_flags & B_INFREECNT) == 0,
2359 ("buf %p still counted as free?", bp));
2362 bp->b_blkno = bp->b_lblkno = 0;
2363 bp->b_offset = NOOFFSET;
2369 bp->b_dirtyoff = bp->b_dirtyend = 0;
2370 bp->b_bufobj = NULL;
2371 bp->b_pin_count = 0;
2372 bp->b_data = bp->b_kvabase;
2373 bp->b_fsprivate1 = NULL;
2374 bp->b_fsprivate2 = NULL;
2375 bp->b_fsprivate3 = NULL;
2377 LIST_INIT(&bp->b_dep);
2381 getnewbuf_scan(int maxsize, int defrag, int unmapped, int metadata)
2383 struct buf *bp, *nbp;
2384 int nqindex, qindex, pass;
2386 KASSERT(!unmapped || !defrag, ("both unmapped and defrag"));
2391 atomic_add_int(&getnewbufrestarts, 1);
2396 * If we're not defragging or low on bufspace attempt to make a new
2397 * buf from a header.
2399 if (defrag == 0 && bufspace + maxsize < hibufspace) {
2400 nqindex = QUEUE_EMPTY;
2401 nbp = TAILQ_FIRST(&bufqueues[nqindex]);
2404 * All available buffers might be clean or we need to start recycling.
2407 nqindex = QUEUE_CLEAN;
2408 nbp = TAILQ_FIRST(&bufqueues[QUEUE_CLEAN]);
2412 * Run scan, possibly freeing data and/or kva mappings on the fly
2415 while ((bp = nbp) != NULL) {
2419 * Calculate next bp (we can only use it if we do not
2420 * release the bqlock)
2422 if ((nbp = TAILQ_NEXT(bp, b_freelist)) == NULL) {
2425 nqindex = QUEUE_CLEAN;
2426 nbp = TAILQ_FIRST(&bufqueues[nqindex]);
2431 if (metadata && pass == 0) {
2433 nqindex = QUEUE_EMPTY;
2434 nbp = TAILQ_FIRST(&bufqueues[nqindex]);
2443 * If we are defragging then we need a buffer with
2444 * b_kvasize != 0. This situation occurs when we
2445 * have many unmapped bufs.
2447 if (defrag && bp->b_kvasize == 0)
2451 * Start freeing the bp. This is somewhat involved. nbp
2452 * remains valid only for QUEUE_EMPTY[KVA] bp's.
2454 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0)
2457 * BKGRDINPROG can only be set with the buf and bufobj
2458 * locks both held. We tolerate a race to clear it here.
2460 if (bp->b_vflags & BV_BKGRDINPROG) {
2466 * Requeue the background write buffer with error.
2468 if ((bp->b_vflags & BV_BKGRDERR) != 0) {
2470 mtx_unlock(&bqclean);
2475 KASSERT(bp->b_qindex == qindex,
2476 ("getnewbuf: inconsistent queue %d bp %p", qindex, bp));
2479 mtx_unlock(&bqclean);
2482 * NOTE: nbp is now entirely invalid. We can only restart
2483 * the scan from this point on.
2485 getnewbuf_reuse_bp(bp, qindex);
2486 mtx_assert(&bqclean, MA_NOTOWNED);
2489 * If we are defragging then free the buffer.
2492 bp->b_flags |= B_INVAL;
2499 * Notify any waiters for the buffer lock about
2500 * identity change by freeing the buffer.
2502 if (qindex == QUEUE_CLEAN && BUF_LOCKWAITERS(bp)) {
2503 bp->b_flags |= B_INVAL;
2512 * If we are overcomitted then recover the buffer and its
2513 * KVM space. This occurs in rare situations when multiple
2514 * processes are blocked in getnewbuf() or allocbuf().
2516 if (bufspace >= hibufspace && bp->b_kvasize != 0) {
2517 bp->b_flags |= B_INVAL;
2529 * Find and initialize a new buffer header, freeing up existing buffers
2530 * in the bufqueues as necessary. The new buffer is returned locked.
2532 * Important: B_INVAL is not set. If the caller wishes to throw the
2533 * buffer away, the caller must set B_INVAL prior to calling brelse().
2536 * We have insufficient buffer headers
2537 * We have insufficient buffer space
2538 * buffer_arena is too fragmented ( space reservation fails )
2539 * If we have to flush dirty buffers ( but we try to avoid this )
2542 getnewbuf(struct vnode *vp, int slpflag, int slptimeo, int size, int maxsize,
2546 int defrag, metadata;
2548 KASSERT((gbflags & (GB_UNMAPPED | GB_KVAALLOC)) != GB_KVAALLOC,
2549 ("GB_KVAALLOC only makes sense with GB_UNMAPPED"));
2550 if (!unmapped_buf_allowed)
2551 gbflags &= ~(GB_UNMAPPED | GB_KVAALLOC);
2554 if (vp == NULL || (vp->v_vflag & (VV_MD | VV_SYSTEM)) != 0 ||
2560 * We can't afford to block since we might be holding a vnode lock,
2561 * which may prevent system daemons from running. We deal with
2562 * low-memory situations by proactively returning memory and running
2563 * async I/O rather then sync I/O.
2565 atomic_add_int(&getnewbufcalls, 1);
2567 bp = getnewbuf_scan(maxsize, defrag, (gbflags & (GB_UNMAPPED |
2568 GB_KVAALLOC)) == GB_UNMAPPED, metadata);
2573 * If we exhausted our list, sleep as appropriate. We may have to
2574 * wakeup various daemons and write out some dirty buffers.
2576 * Generally we are sleeping due to insufficient buffer space.
2579 mtx_assert(&bqclean, MA_OWNED);
2580 getnewbuf_bufd_help(vp, gbflags, slpflag, slptimeo, defrag);
2581 mtx_assert(&bqclean, MA_NOTOWNED);
2582 } else if ((gbflags & (GB_UNMAPPED | GB_KVAALLOC)) == GB_UNMAPPED) {
2583 mtx_assert(&bqclean, MA_NOTOWNED);
2586 atomic_add_int(&bufreusecnt, 1);
2588 mtx_assert(&bqclean, MA_NOTOWNED);
2591 * We finally have a valid bp. We aren't quite out of the
2592 * woods, we still have to reserve kva space. In order to
2593 * keep fragmentation sane we only allocate kva in BKVASIZE
2596 maxsize = (maxsize + BKVAMASK) & ~BKVAMASK;
2598 if (maxsize != bp->b_kvasize &&
2599 bufkvaalloc(bp, maxsize, gbflags)) {
2601 bp->b_flags |= B_INVAL;
2604 } else if ((gbflags & (GB_UNMAPPED | GB_KVAALLOC)) ==
2605 (GB_UNMAPPED | GB_KVAALLOC)) {
2606 bp->b_data = unmapped_buf;
2607 BUF_CHECK_UNMAPPED(bp);
2609 atomic_add_int(&bufreusecnt, 1);
2617 * buffer flushing daemon. Buffers are normally flushed by the
2618 * update daemon but if it cannot keep up this process starts to
2619 * take the load in an attempt to prevent getnewbuf() from blocking.
2622 static struct kproc_desc buf_kp = {
2627 SYSINIT(bufdaemon, SI_SUB_KTHREAD_BUF, SI_ORDER_FIRST, kproc_start, &buf_kp);
2630 buf_flush(struct vnode *vp, int target)
2634 flushed = flushbufqueues(vp, target, 0);
2637 * Could not find any buffers without rollback
2638 * dependencies, so just write the first one
2639 * in the hopes of eventually making progress.
2641 if (vp != NULL && target > 2)
2643 flushbufqueues(vp, target, 1);
2654 * This process needs to be suspended prior to shutdown sync.
2656 EVENTHANDLER_REGISTER(shutdown_pre_sync, kproc_shutdown, bufdaemonproc,
2660 * This process is allowed to take the buffer cache to the limit
2662 curthread->td_pflags |= TDP_NORUNNINGBUF | TDP_BUFNEED;
2666 mtx_unlock(&bdlock);
2668 kproc_suspend_check(bufdaemonproc);
2669 lodirty = lodirtybuffers;
2670 if (bd_speedupreq) {
2671 lodirty = numdirtybuffers / 2;
2675 * Do the flush. Limit the amount of in-transit I/O we
2676 * allow to build up, otherwise we would completely saturate
2679 while (numdirtybuffers > lodirty) {
2680 if (buf_flush(NULL, numdirtybuffers - lodirty) == 0)
2682 kern_yield(PRI_USER);
2686 * Only clear bd_request if we have reached our low water
2687 * mark. The buf_daemon normally waits 1 second and
2688 * then incrementally flushes any dirty buffers that have
2689 * built up, within reason.
2691 * If we were unable to hit our low water mark and couldn't
2692 * find any flushable buffers, we sleep for a short period
2693 * to avoid endless loops on unlockable buffers.
2696 if (numdirtybuffers <= lodirtybuffers) {
2698 * We reached our low water mark, reset the
2699 * request and sleep until we are needed again.
2700 * The sleep is just so the suspend code works.
2704 * Do an extra wakeup in case dirty threshold
2705 * changed via sysctl and the explicit transition
2706 * out of shortfall was missed.
2709 if (runningbufspace <= lorunningspace)
2711 msleep(&bd_request, &bdlock, PVM, "psleep", hz);
2714 * We couldn't find any flushable dirty buffers but
2715 * still have too many dirty buffers, we
2716 * have to sleep and try again. (rare)
2718 msleep(&bd_request, &bdlock, PVM, "qsleep", hz / 10);
2726 * Try to flush a buffer in the dirty queue. We must be careful to
2727 * free up B_INVAL buffers instead of write them, which NFS is
2728 * particularly sensitive to.
2730 static int flushwithdeps = 0;
2731 SYSCTL_INT(_vfs, OID_AUTO, flushwithdeps, CTLFLAG_RW, &flushwithdeps,
2732 0, "Number of buffers flushed with dependecies that require rollbacks");
2735 flushbufqueues(struct vnode *lvp, int target, int flushdeps)
2737 struct buf *sentinel;
2748 queue = QUEUE_DIRTY;
2750 sentinel = malloc(sizeof(struct buf), M_TEMP, M_WAITOK | M_ZERO);
2751 sentinel->b_qindex = QUEUE_SENTINEL;
2753 TAILQ_INSERT_HEAD(&bufqueues[queue], sentinel, b_freelist);
2754 mtx_unlock(&bqdirty);
2755 while (flushed != target) {
2758 bp = TAILQ_NEXT(sentinel, b_freelist);
2760 TAILQ_REMOVE(&bufqueues[queue], sentinel, b_freelist);
2761 TAILQ_INSERT_AFTER(&bufqueues[queue], bp, sentinel,
2764 mtx_unlock(&bqdirty);
2768 * Skip sentinels inserted by other invocations of the
2769 * flushbufqueues(), taking care to not reorder them.
2771 * Only flush the buffers that belong to the
2772 * vnode locked by the curthread.
2774 if (bp->b_qindex == QUEUE_SENTINEL || (lvp != NULL &&
2776 mtx_unlock(&bqdirty);
2779 error = BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL);
2780 mtx_unlock(&bqdirty);
2783 if (bp->b_pin_count > 0) {
2788 * BKGRDINPROG can only be set with the buf and bufobj
2789 * locks both held. We tolerate a race to clear it here.
2791 if ((bp->b_vflags & BV_BKGRDINPROG) != 0 ||
2792 (bp->b_flags & B_DELWRI) == 0) {
2796 if (bp->b_flags & B_INVAL) {
2803 if (!LIST_EMPTY(&bp->b_dep) && buf_countdeps(bp, 0)) {
2804 if (flushdeps == 0) {
2812 * We must hold the lock on a vnode before writing
2813 * one of its buffers. Otherwise we may confuse, or
2814 * in the case of a snapshot vnode, deadlock the
2817 * The lock order here is the reverse of the normal
2818 * of vnode followed by buf lock. This is ok because
2819 * the NOWAIT will prevent deadlock.
2822 if (vn_start_write(vp, &mp, V_NOWAIT) != 0) {
2828 error = vn_lock(vp, LK_EXCLUSIVE | LK_NOWAIT);
2830 ASSERT_VOP_LOCKED(vp, "getbuf");
2832 error = VOP_ISLOCKED(vp) == LK_EXCLUSIVE ? 0 :
2833 vn_lock(vp, LK_TRYUPGRADE);
2836 CTR3(KTR_BUF, "flushbufqueue(%p) vp %p flags %X",
2837 bp, bp->b_vp, bp->b_flags);
2838 if (curproc == bufdaemonproc) {
2845 vn_finished_write(mp);
2848 flushwithdeps += hasdeps;
2852 * Sleeping on runningbufspace while holding
2853 * vnode lock leads to deadlock.
2855 if (curproc == bufdaemonproc &&
2856 runningbufspace > hirunningspace)
2857 waitrunningbufspace();
2860 vn_finished_write(mp);
2864 TAILQ_REMOVE(&bufqueues[queue], sentinel, b_freelist);
2865 mtx_unlock(&bqdirty);
2866 free(sentinel, M_TEMP);
2871 * Check to see if a block is currently memory resident.
2874 incore(struct bufobj *bo, daddr_t blkno)
2879 bp = gbincore(bo, blkno);
2885 * Returns true if no I/O is needed to access the
2886 * associated VM object. This is like incore except
2887 * it also hunts around in the VM system for the data.
2891 inmem(struct vnode * vp, daddr_t blkno)
2894 vm_offset_t toff, tinc, size;
2898 ASSERT_VOP_LOCKED(vp, "inmem");
2900 if (incore(&vp->v_bufobj, blkno))
2902 if (vp->v_mount == NULL)
2909 if (size > vp->v_mount->mnt_stat.f_iosize)
2910 size = vp->v_mount->mnt_stat.f_iosize;
2911 off = (vm_ooffset_t)blkno * (vm_ooffset_t)vp->v_mount->mnt_stat.f_iosize;
2913 VM_OBJECT_RLOCK(obj);
2914 for (toff = 0; toff < vp->v_mount->mnt_stat.f_iosize; toff += tinc) {
2915 m = vm_page_lookup(obj, OFF_TO_IDX(off + toff));
2919 if (tinc > PAGE_SIZE - ((toff + off) & PAGE_MASK))
2920 tinc = PAGE_SIZE - ((toff + off) & PAGE_MASK);
2921 if (vm_page_is_valid(m,
2922 (vm_offset_t) ((toff + off) & PAGE_MASK), tinc) == 0)
2925 VM_OBJECT_RUNLOCK(obj);
2929 VM_OBJECT_RUNLOCK(obj);
2934 * Set the dirty range for a buffer based on the status of the dirty
2935 * bits in the pages comprising the buffer. The range is limited
2936 * to the size of the buffer.
2938 * Tell the VM system that the pages associated with this buffer
2939 * are clean. This is used for delayed writes where the data is
2940 * going to go to disk eventually without additional VM intevention.
2942 * Note that while we only really need to clean through to b_bcount, we
2943 * just go ahead and clean through to b_bufsize.
2946 vfs_clean_pages_dirty_buf(struct buf *bp)
2948 vm_ooffset_t foff, noff, eoff;
2952 if ((bp->b_flags & B_VMIO) == 0 || bp->b_bufsize == 0)
2955 foff = bp->b_offset;
2956 KASSERT(bp->b_offset != NOOFFSET,
2957 ("vfs_clean_pages_dirty_buf: no buffer offset"));
2959 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object);
2960 vfs_drain_busy_pages(bp);
2961 vfs_setdirty_locked_object(bp);
2962 for (i = 0; i < bp->b_npages; i++) {
2963 noff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK;
2965 if (eoff > bp->b_offset + bp->b_bufsize)
2966 eoff = bp->b_offset + bp->b_bufsize;
2968 vfs_page_set_validclean(bp, foff, m);
2969 /* vm_page_clear_dirty(m, foff & PAGE_MASK, eoff - foff); */
2972 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object);
2976 vfs_setdirty_locked_object(struct buf *bp)
2981 object = bp->b_bufobj->bo_object;
2982 VM_OBJECT_ASSERT_WLOCKED(object);
2985 * We qualify the scan for modified pages on whether the
2986 * object has been flushed yet.
2988 if ((object->flags & OBJ_MIGHTBEDIRTY) != 0) {
2989 vm_offset_t boffset;
2990 vm_offset_t eoffset;
2993 * test the pages to see if they have been modified directly
2994 * by users through the VM system.
2996 for (i = 0; i < bp->b_npages; i++)
2997 vm_page_test_dirty(bp->b_pages[i]);
3000 * Calculate the encompassing dirty range, boffset and eoffset,
3001 * (eoffset - boffset) bytes.
3004 for (i = 0; i < bp->b_npages; i++) {
3005 if (bp->b_pages[i]->dirty)
3008 boffset = (i << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK);
3010 for (i = bp->b_npages - 1; i >= 0; --i) {
3011 if (bp->b_pages[i]->dirty) {
3015 eoffset = ((i + 1) << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK);
3018 * Fit it to the buffer.
3021 if (eoffset > bp->b_bcount)
3022 eoffset = bp->b_bcount;
3025 * If we have a good dirty range, merge with the existing
3029 if (boffset < eoffset) {
3030 if (bp->b_dirtyoff > boffset)
3031 bp->b_dirtyoff = boffset;
3032 if (bp->b_dirtyend < eoffset)
3033 bp->b_dirtyend = eoffset;
3039 * Allocate the KVA mapping for an existing buffer.
3040 * If an unmapped buffer is provided but a mapped buffer is requested, take
3041 * also care to properly setup mappings between pages and KVA.
3044 bp_unmapped_get_kva(struct buf *bp, daddr_t blkno, int size, int gbflags)
3046 struct buf *scratch_bp;
3047 int bsize, maxsize, need_mapping, need_kva;
3050 need_mapping = bp->b_data == unmapped_buf &&
3051 (gbflags & GB_UNMAPPED) == 0;
3052 need_kva = bp->b_kvabase == unmapped_buf &&
3053 bp->b_data == unmapped_buf &&
3054 (gbflags & GB_KVAALLOC) != 0;
3055 if (!need_mapping && !need_kva)
3058 BUF_CHECK_UNMAPPED(bp);
3060 if (need_mapping && bp->b_kvabase != unmapped_buf) {
3062 * Buffer is not mapped, but the KVA was already
3063 * reserved at the time of the instantiation. Use the
3070 * Calculate the amount of the address space we would reserve
3071 * if the buffer was mapped.
3073 bsize = vn_isdisk(bp->b_vp, NULL) ? DEV_BSIZE : bp->b_bufobj->bo_bsize;
3074 KASSERT(bsize != 0, ("bsize == 0, check bo->bo_bsize"));
3075 offset = blkno * bsize;
3076 maxsize = size + (offset & PAGE_MASK);
3077 maxsize = imax(maxsize, bsize);
3080 if (bufkvaalloc(bp, maxsize, gbflags)) {
3082 * Request defragmentation. getnewbuf() returns us the
3083 * allocated space by the scratch buffer KVA.
3085 scratch_bp = getnewbuf(bp->b_vp, 0, 0, size, maxsize, gbflags |
3086 (GB_UNMAPPED | GB_KVAALLOC));
3087 if (scratch_bp == NULL) {
3088 if ((gbflags & GB_NOWAIT_BD) != 0) {
3090 * XXXKIB: defragmentation cannot
3091 * succeed, not sure what else to do.
3093 panic("GB_NOWAIT_BD and GB_UNMAPPED %p", bp);
3095 atomic_add_int(&mappingrestarts, 1);
3098 KASSERT(scratch_bp->b_kvabase != unmapped_buf,
3099 ("scratch bp has no KVA %p", scratch_bp));
3100 /* Grab pointers. */
3101 bp->b_kvabase = scratch_bp->b_kvabase;
3102 bp->b_kvasize = scratch_bp->b_kvasize;
3103 bp->b_data = scratch_bp->b_data;
3105 /* Get rid of the scratch buffer. */
3106 scratch_bp->b_kvasize = 0;
3107 scratch_bp->b_flags |= B_INVAL;
3108 scratch_bp->b_data = scratch_bp->b_kvabase = unmapped_buf;
3113 /* b_offset is handled by bpmap_qenter. */
3114 bp->b_data = bp->b_kvabase;
3115 BUF_CHECK_MAPPED(bp);
3123 * Get a block given a specified block and offset into a file/device.
3124 * The buffers B_DONE bit will be cleared on return, making it almost
3125 * ready for an I/O initiation. B_INVAL may or may not be set on
3126 * return. The caller should clear B_INVAL prior to initiating a
3129 * For a non-VMIO buffer, B_CACHE is set to the opposite of B_INVAL for
3130 * an existing buffer.
3132 * For a VMIO buffer, B_CACHE is modified according to the backing VM.
3133 * If getblk()ing a previously 0-sized invalid buffer, B_CACHE is set
3134 * and then cleared based on the backing VM. If the previous buffer is
3135 * non-0-sized but invalid, B_CACHE will be cleared.
3137 * If getblk() must create a new buffer, the new buffer is returned with
3138 * both B_INVAL and B_CACHE clear unless it is a VMIO buffer, in which
3139 * case it is returned with B_INVAL clear and B_CACHE set based on the
3142 * getblk() also forces a bwrite() for any B_DELWRI buffer whos
3143 * B_CACHE bit is clear.
3145 * What this means, basically, is that the caller should use B_CACHE to
3146 * determine whether the buffer is fully valid or not and should clear
3147 * B_INVAL prior to issuing a read. If the caller intends to validate
3148 * the buffer by loading its data area with something, the caller needs
3149 * to clear B_INVAL. If the caller does this without issuing an I/O,
3150 * the caller should set B_CACHE ( as an optimization ), else the caller
3151 * should issue the I/O and biodone() will set B_CACHE if the I/O was
3152 * a write attempt or if it was a successfull read. If the caller
3153 * intends to issue a READ, the caller must clear B_INVAL and BIO_ERROR
3154 * prior to issuing the READ. biodone() will *not* clear B_INVAL.
3157 getblk(struct vnode *vp, daddr_t blkno, int size, int slpflag, int slptimeo,
3162 int bsize, error, maxsize, vmio;
3165 CTR3(KTR_BUF, "getblk(%p, %ld, %d)", vp, (long)blkno, size);
3166 KASSERT((flags & (GB_UNMAPPED | GB_KVAALLOC)) != GB_KVAALLOC,
3167 ("GB_KVAALLOC only makes sense with GB_UNMAPPED"));
3168 ASSERT_VOP_LOCKED(vp, "getblk");
3169 if (size > MAXBCACHEBUF)
3170 panic("getblk: size(%d) > MAXBCACHEBUF(%d)\n", size,
3172 if (!unmapped_buf_allowed)
3173 flags &= ~(GB_UNMAPPED | GB_KVAALLOC);
3178 bp = gbincore(bo, blkno);
3182 * Buffer is in-core. If the buffer is not busy nor managed,
3183 * it must be on a queue.
3185 lockflags = LK_EXCLUSIVE | LK_SLEEPFAIL | LK_INTERLOCK;
3187 if (flags & GB_LOCK_NOWAIT)
3188 lockflags |= LK_NOWAIT;
3190 error = BUF_TIMELOCK(bp, lockflags,
3191 BO_LOCKPTR(bo), "getblk", slpflag, slptimeo);
3194 * If we slept and got the lock we have to restart in case
3195 * the buffer changed identities.
3197 if (error == ENOLCK)
3199 /* We timed out or were interrupted. */
3202 /* If recursed, assume caller knows the rules. */
3203 else if (BUF_LOCKRECURSED(bp))
3207 * The buffer is locked. B_CACHE is cleared if the buffer is
3208 * invalid. Otherwise, for a non-VMIO buffer, B_CACHE is set
3209 * and for a VMIO buffer B_CACHE is adjusted according to the
3212 if (bp->b_flags & B_INVAL)
3213 bp->b_flags &= ~B_CACHE;
3214 else if ((bp->b_flags & (B_VMIO | B_INVAL)) == 0)
3215 bp->b_flags |= B_CACHE;
3216 if (bp->b_flags & B_MANAGED)
3217 MPASS(bp->b_qindex == QUEUE_NONE);
3222 * check for size inconsistencies for non-VMIO case.
3224 if (bp->b_bcount != size) {
3225 if ((bp->b_flags & B_VMIO) == 0 ||
3226 (size > bp->b_kvasize)) {
3227 if (bp->b_flags & B_DELWRI) {
3229 * If buffer is pinned and caller does
3230 * not want sleep waiting for it to be
3231 * unpinned, bail out
3233 if (bp->b_pin_count > 0) {
3234 if (flags & GB_LOCK_NOWAIT) {
3241 bp->b_flags |= B_NOCACHE;
3244 if (LIST_EMPTY(&bp->b_dep)) {
3245 bp->b_flags |= B_RELBUF;
3248 bp->b_flags |= B_NOCACHE;
3257 * Handle the case of unmapped buffer which should
3258 * become mapped, or the buffer for which KVA
3259 * reservation is requested.
3261 bp_unmapped_get_kva(bp, blkno, size, flags);
3264 * If the size is inconsistant in the VMIO case, we can resize
3265 * the buffer. This might lead to B_CACHE getting set or
3266 * cleared. If the size has not changed, B_CACHE remains
3267 * unchanged from its previous state.
3269 if (bp->b_bcount != size)
3272 KASSERT(bp->b_offset != NOOFFSET,
3273 ("getblk: no buffer offset"));
3276 * A buffer with B_DELWRI set and B_CACHE clear must
3277 * be committed before we can return the buffer in
3278 * order to prevent the caller from issuing a read
3279 * ( due to B_CACHE not being set ) and overwriting
3282 * Most callers, including NFS and FFS, need this to
3283 * operate properly either because they assume they
3284 * can issue a read if B_CACHE is not set, or because
3285 * ( for example ) an uncached B_DELWRI might loop due
3286 * to softupdates re-dirtying the buffer. In the latter
3287 * case, B_CACHE is set after the first write completes,
3288 * preventing further loops.
3289 * NOTE! b*write() sets B_CACHE. If we cleared B_CACHE
3290 * above while extending the buffer, we cannot allow the
3291 * buffer to remain with B_CACHE set after the write
3292 * completes or it will represent a corrupt state. To
3293 * deal with this we set B_NOCACHE to scrap the buffer
3296 * We might be able to do something fancy, like setting
3297 * B_CACHE in bwrite() except if B_DELWRI is already set,
3298 * so the below call doesn't set B_CACHE, but that gets real
3299 * confusing. This is much easier.
3302 if ((bp->b_flags & (B_CACHE|B_DELWRI)) == B_DELWRI) {
3303 bp->b_flags |= B_NOCACHE;
3307 bp->b_flags &= ~B_DONE;
3310 * Buffer is not in-core, create new buffer. The buffer
3311 * returned by getnewbuf() is locked. Note that the returned
3312 * buffer is also considered valid (not marked B_INVAL).
3316 * If the user does not want us to create the buffer, bail out
3319 if (flags & GB_NOCREAT)
3321 if (numfreebuffers == 0 && TD_IS_IDLETHREAD(curthread))
3324 bsize = vn_isdisk(vp, NULL) ? DEV_BSIZE : bo->bo_bsize;
3325 KASSERT(bsize != 0, ("bsize == 0, check bo->bo_bsize"));
3326 offset = blkno * bsize;
3327 vmio = vp->v_object != NULL;
3329 maxsize = size + (offset & PAGE_MASK);
3332 /* Do not allow non-VMIO notmapped buffers. */
3333 flags &= ~(GB_UNMAPPED | GB_KVAALLOC);
3335 maxsize = imax(maxsize, bsize);
3337 bp = getnewbuf(vp, slpflag, slptimeo, size, maxsize, flags);
3339 if (slpflag || slptimeo)
3345 * This code is used to make sure that a buffer is not
3346 * created while the getnewbuf routine is blocked.
3347 * This can be a problem whether the vnode is locked or not.
3348 * If the buffer is created out from under us, we have to
3349 * throw away the one we just created.
3351 * Note: this must occur before we associate the buffer
3352 * with the vp especially considering limitations in
3353 * the splay tree implementation when dealing with duplicate
3357 if (gbincore(bo, blkno)) {
3359 bp->b_flags |= B_INVAL;
3365 * Insert the buffer into the hash, so that it can
3366 * be found by incore.
3368 bp->b_blkno = bp->b_lblkno = blkno;
3369 bp->b_offset = offset;
3374 * set B_VMIO bit. allocbuf() the buffer bigger. Since the
3375 * buffer size starts out as 0, B_CACHE will be set by
3376 * allocbuf() for the VMIO case prior to it testing the
3377 * backing store for validity.
3381 bp->b_flags |= B_VMIO;
3382 KASSERT(vp->v_object == bp->b_bufobj->bo_object,
3383 ("ARGH! different b_bufobj->bo_object %p %p %p\n",
3384 bp, vp->v_object, bp->b_bufobj->bo_object));
3386 bp->b_flags &= ~B_VMIO;
3387 KASSERT(bp->b_bufobj->bo_object == NULL,
3388 ("ARGH! has b_bufobj->bo_object %p %p\n",
3389 bp, bp->b_bufobj->bo_object));
3390 BUF_CHECK_MAPPED(bp);
3394 bp->b_flags &= ~B_DONE;
3396 CTR4(KTR_BUF, "getblk(%p, %ld, %d) = %p", vp, (long)blkno, size, bp);
3397 BUF_ASSERT_HELD(bp);
3399 KASSERT(bp->b_bufobj == bo,
3400 ("bp %p wrong b_bufobj %p should be %p", bp, bp->b_bufobj, bo));
3405 * Get an empty, disassociated buffer of given size. The buffer is initially
3409 geteblk(int size, int flags)
3414 maxsize = (size + BKVAMASK) & ~BKVAMASK;
3415 while ((bp = getnewbuf(NULL, 0, 0, size, maxsize, flags)) == NULL) {
3416 if ((flags & GB_NOWAIT_BD) &&
3417 (curthread->td_pflags & TDP_BUFNEED) != 0)
3421 bp->b_flags |= B_INVAL; /* b_dep cleared by getnewbuf() */
3422 BUF_ASSERT_HELD(bp);
3427 * This code constitutes the buffer memory from either anonymous system
3428 * memory (in the case of non-VMIO operations) or from an associated
3429 * VM object (in the case of VMIO operations). This code is able to
3430 * resize a buffer up or down.
3432 * Note that this code is tricky, and has many complications to resolve
3433 * deadlock or inconsistant data situations. Tread lightly!!!
3434 * There are B_CACHE and B_DELWRI interactions that must be dealt with by
3435 * the caller. Calling this code willy nilly can result in the loss of data.
3437 * allocbuf() only adjusts B_CACHE for VMIO buffers. getblk() deals with
3438 * B_CACHE for the non-VMIO case.
3442 allocbuf(struct buf *bp, int size)
3444 int newbsize, mbsize;
3447 BUF_ASSERT_HELD(bp);
3449 if (bp->b_kvasize != 0 && bp->b_kvasize < size)
3450 panic("allocbuf: buffer too small");
3452 if ((bp->b_flags & B_VMIO) == 0) {
3456 * Just get anonymous memory from the kernel. Don't
3457 * mess with B_CACHE.
3459 mbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1);
3460 if (bp->b_flags & B_MALLOC)
3463 newbsize = round_page(size);
3465 if (newbsize < bp->b_bufsize) {
3467 * malloced buffers are not shrunk
3469 if (bp->b_flags & B_MALLOC) {
3471 bp->b_bcount = size;
3473 free(bp->b_data, M_BIOBUF);
3474 bufmallocadjust(bp, 0);
3475 bp->b_data = bp->b_kvabase;
3477 bp->b_flags &= ~B_MALLOC;
3481 vm_hold_free_pages(bp, newbsize);
3482 } else if (newbsize > bp->b_bufsize) {
3484 * We only use malloced memory on the first allocation.
3485 * and revert to page-allocated memory when the buffer
3489 * There is a potential smp race here that could lead
3490 * to bufmallocspace slightly passing the max. It
3491 * is probably extremely rare and not worth worrying
3494 if ((bufmallocspace < maxbufmallocspace) &&
3495 (bp->b_bufsize == 0) &&
3496 (mbsize <= PAGE_SIZE/2)) {
3498 bp->b_data = malloc(mbsize, M_BIOBUF, M_WAITOK);
3499 bp->b_bcount = size;
3500 bp->b_flags |= B_MALLOC;
3501 bufmallocadjust(bp, mbsize);
3507 * If the buffer is growing on its other-than-first
3508 * allocation then we revert to the page-allocation
3511 if (bp->b_flags & B_MALLOC) {
3512 origbuf = bp->b_data;
3513 origbufsize = bp->b_bufsize;
3514 bp->b_data = bp->b_kvabase;
3515 bufmallocadjust(bp, 0);
3516 bp->b_flags &= ~B_MALLOC;
3517 newbsize = round_page(newbsize);
3521 (vm_offset_t) bp->b_data + bp->b_bufsize,
3522 (vm_offset_t) bp->b_data + newbsize);
3524 bcopy(origbuf, bp->b_data, origbufsize);
3525 free(origbuf, M_BIOBUF);
3531 newbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1);
3532 desiredpages = (size == 0) ? 0 :
3533 num_pages((bp->b_offset & PAGE_MASK) + newbsize);
3535 if (bp->b_flags & B_MALLOC)
3536 panic("allocbuf: VMIO buffer can't be malloced");
3538 * Set B_CACHE initially if buffer is 0 length or will become
3541 if (size == 0 || bp->b_bufsize == 0)
3542 bp->b_flags |= B_CACHE;
3544 if (newbsize < bp->b_bufsize) {
3546 * DEV_BSIZE aligned new buffer size is less then the
3547 * DEV_BSIZE aligned existing buffer size. Figure out
3548 * if we have to remove any pages.
3550 if (desiredpages < bp->b_npages) {
3553 if (buf_mapped(bp)) {
3554 BUF_CHECK_MAPPED(bp);
3555 pmap_qremove((vm_offset_t)trunc_page(
3556 (vm_offset_t)bp->b_data) +
3557 (desiredpages << PAGE_SHIFT),
3558 (bp->b_npages - desiredpages));
3560 BUF_CHECK_UNMAPPED(bp);
3561 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object);
3562 for (i = desiredpages; i < bp->b_npages; i++) {
3564 * the page is not freed here -- it
3565 * is the responsibility of
3566 * vnode_pager_setsize
3569 KASSERT(m != bogus_page,
3570 ("allocbuf: bogus page found"));
3571 while (vm_page_sleep_if_busy(m,
3575 bp->b_pages[i] = NULL;
3577 vm_page_unwire(m, PQ_INACTIVE);
3580 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object);
3581 bp->b_npages = desiredpages;
3583 } else if (size > bp->b_bcount) {
3585 * We are growing the buffer, possibly in a
3586 * byte-granular fashion.
3593 * Step 1, bring in the VM pages from the object,
3594 * allocating them if necessary. We must clear
3595 * B_CACHE if these pages are not valid for the
3596 * range covered by the buffer.
3599 obj = bp->b_bufobj->bo_object;
3601 VM_OBJECT_WLOCK(obj);
3602 while (bp->b_npages < desiredpages) {
3606 * We must allocate system pages since blocking
3607 * here could interfere with paging I/O, no
3608 * matter which process we are.
3610 * Only exclusive busy can be tested here.
3611 * Blocking on shared busy might lead to
3612 * deadlocks once allocbuf() is called after
3613 * pages are vfs_busy_pages().
3615 m = vm_page_grab(obj, OFF_TO_IDX(bp->b_offset) +
3616 bp->b_npages, VM_ALLOC_NOBUSY |
3617 VM_ALLOC_SYSTEM | VM_ALLOC_WIRED |
3618 VM_ALLOC_IGN_SBUSY |
3619 VM_ALLOC_COUNT(desiredpages - bp->b_npages));
3621 bp->b_flags &= ~B_CACHE;
3622 bp->b_pages[bp->b_npages] = m;
3627 * Step 2. We've loaded the pages into the buffer,
3628 * we have to figure out if we can still have B_CACHE
3629 * set. Note that B_CACHE is set according to the
3630 * byte-granular range ( bcount and size ), new the
3631 * aligned range ( newbsize ).
3633 * The VM test is against m->valid, which is DEV_BSIZE
3634 * aligned. Needless to say, the validity of the data
3635 * needs to also be DEV_BSIZE aligned. Note that this
3636 * fails with NFS if the server or some other client
3637 * extends the file's EOF. If our buffer is resized,
3638 * B_CACHE may remain set! XXX
3641 toff = bp->b_bcount;
3642 tinc = PAGE_SIZE - ((bp->b_offset + toff) & PAGE_MASK);
3644 while ((bp->b_flags & B_CACHE) && toff < size) {
3647 if (tinc > (size - toff))
3650 pi = ((bp->b_offset & PAGE_MASK) + toff) >>
3663 VM_OBJECT_WUNLOCK(obj);
3666 * Step 3, fixup the KVA pmap.
3671 BUF_CHECK_UNMAPPED(bp);
3674 /* Record changes in allocation size. */
3675 if (bp->b_bufsize != newbsize)
3676 bufspaceadjust(bp, newbsize);
3677 bp->b_bcount = size; /* requested buffer size. */
3681 extern int inflight_transient_maps;
3684 biodone(struct bio *bp)
3687 void (*done)(struct bio *);
3688 vm_offset_t start, end;
3690 if ((bp->bio_flags & BIO_TRANSIENT_MAPPING) != 0) {
3691 bp->bio_flags &= ~BIO_TRANSIENT_MAPPING;
3692 bp->bio_flags |= BIO_UNMAPPED;
3693 start = trunc_page((vm_offset_t)bp->bio_data);
3694 end = round_page((vm_offset_t)bp->bio_data + bp->bio_length);
3695 bp->bio_data = unmapped_buf;
3696 pmap_qremove(start, OFF_TO_IDX(end - start));
3697 vmem_free(transient_arena, start, end - start);
3698 atomic_add_int(&inflight_transient_maps, -1);
3700 done = bp->bio_done;
3702 mtxp = mtx_pool_find(mtxpool_sleep, bp);
3704 bp->bio_flags |= BIO_DONE;
3708 bp->bio_flags |= BIO_DONE;
3714 * Wait for a BIO to finish.
3717 biowait(struct bio *bp, const char *wchan)
3721 mtxp = mtx_pool_find(mtxpool_sleep, bp);
3723 while ((bp->bio_flags & BIO_DONE) == 0)
3724 msleep(bp, mtxp, PRIBIO, wchan, 0);
3726 if (bp->bio_error != 0)
3727 return (bp->bio_error);
3728 if (!(bp->bio_flags & BIO_ERROR))
3734 biofinish(struct bio *bp, struct devstat *stat, int error)
3738 bp->bio_error = error;
3739 bp->bio_flags |= BIO_ERROR;
3742 devstat_end_transaction_bio(stat, bp);
3749 * Wait for buffer I/O completion, returning error status. The buffer
3750 * is left locked and B_DONE on return. B_EINTR is converted into an EINTR
3751 * error and cleared.
3754 bufwait(struct buf *bp)
3756 if (bp->b_iocmd == BIO_READ)
3757 bwait(bp, PRIBIO, "biord");
3759 bwait(bp, PRIBIO, "biowr");
3760 if (bp->b_flags & B_EINTR) {
3761 bp->b_flags &= ~B_EINTR;
3764 if (bp->b_ioflags & BIO_ERROR) {
3765 return (bp->b_error ? bp->b_error : EIO);
3772 * Call back function from struct bio back up to struct buf.
3775 bufdonebio(struct bio *bip)
3779 bp = bip->bio_caller2;
3780 bp->b_resid = bip->bio_resid;
3781 bp->b_ioflags = bip->bio_flags;
3782 bp->b_error = bip->bio_error;
3784 bp->b_ioflags |= BIO_ERROR;
3790 dev_strategy(struct cdev *dev, struct buf *bp)
3795 KASSERT(dev->si_refcount > 0,
3796 ("dev_strategy on un-referenced struct cdev *(%s) %p",
3797 devtoname(dev), dev));
3799 csw = dev_refthread(dev, &ref);
3800 dev_strategy_csw(dev, csw, bp);
3801 dev_relthread(dev, ref);
3805 dev_strategy_csw(struct cdev *dev, struct cdevsw *csw, struct buf *bp)
3809 KASSERT(bp->b_iocmd == BIO_READ || bp->b_iocmd == BIO_WRITE,
3811 KASSERT(((dev->si_flags & SI_ETERNAL) != 0 && csw != NULL) ||
3812 dev->si_threadcount > 0,
3813 ("dev_strategy_csw threadcount cdev *(%s) %p", devtoname(dev),
3816 bp->b_error = ENXIO;
3817 bp->b_ioflags = BIO_ERROR;
3825 /* Try again later */
3826 tsleep(&bp, PRIBIO, "dev_strat", hz/10);
3828 bip->bio_cmd = bp->b_iocmd;
3829 bip->bio_offset = bp->b_iooffset;
3830 bip->bio_length = bp->b_bcount;
3831 bip->bio_bcount = bp->b_bcount; /* XXX: remove */
3833 bip->bio_done = bufdonebio;
3834 bip->bio_caller2 = bp;
3836 (*csw->d_strategy)(bip);
3842 * Finish I/O on a buffer, optionally calling a completion function.
3843 * This is usually called from an interrupt so process blocking is
3846 * biodone is also responsible for setting B_CACHE in a B_VMIO bp.
3847 * In a non-VMIO bp, B_CACHE will be set on the next getblk()
3848 * assuming B_INVAL is clear.
3850 * For the VMIO case, we set B_CACHE if the op was a read and no
3851 * read error occured, or if the op was a write. B_CACHE is never
3852 * set if the buffer is invalid or otherwise uncacheable.
3854 * biodone does not mess with B_INVAL, allowing the I/O routine or the
3855 * initiator to leave B_INVAL set to brelse the buffer out of existance
3856 * in the biodone routine.
3859 bufdone(struct buf *bp)
3861 struct bufobj *dropobj;
3862 void (*biodone)(struct buf *);
3864 CTR3(KTR_BUF, "bufdone(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
3867 KASSERT(!(bp->b_flags & B_DONE), ("biodone: bp %p already done", bp));
3868 BUF_ASSERT_HELD(bp);
3870 runningbufwakeup(bp);
3871 if (bp->b_iocmd == BIO_WRITE)
3872 dropobj = bp->b_bufobj;
3873 /* call optional completion function if requested */
3874 if (bp->b_iodone != NULL) {
3875 biodone = bp->b_iodone;
3876 bp->b_iodone = NULL;
3879 bufobj_wdrop(dropobj);
3886 bufobj_wdrop(dropobj);
3890 bufdone_finish(struct buf *bp)
3892 BUF_ASSERT_HELD(bp);
3894 if (!LIST_EMPTY(&bp->b_dep))
3897 if (bp->b_flags & B_VMIO) {
3902 int bogus, i, iosize;
3904 obj = bp->b_bufobj->bo_object;
3905 KASSERT(obj->paging_in_progress >= bp->b_npages,
3906 ("biodone_finish: paging in progress(%d) < b_npages(%d)",
3907 obj->paging_in_progress, bp->b_npages));
3910 KASSERT(vp->v_holdcnt > 0,
3911 ("biodone_finish: vnode %p has zero hold count", vp));
3912 KASSERT(vp->v_object != NULL,
3913 ("biodone_finish: vnode %p has no vm_object", vp));
3915 foff = bp->b_offset;
3916 KASSERT(bp->b_offset != NOOFFSET,
3917 ("biodone_finish: bp %p has no buffer offset", bp));
3920 * Set B_CACHE if the op was a normal read and no error
3921 * occured. B_CACHE is set for writes in the b*write()
3924 iosize = bp->b_bcount - bp->b_resid;
3925 if (bp->b_iocmd == BIO_READ &&
3926 !(bp->b_flags & (B_INVAL|B_NOCACHE)) &&
3927 !(bp->b_ioflags & BIO_ERROR)) {
3928 bp->b_flags |= B_CACHE;
3931 VM_OBJECT_WLOCK(obj);
3932 for (i = 0; i < bp->b_npages; i++) {
3936 resid = ((foff + PAGE_SIZE) & ~(off_t)PAGE_MASK) - foff;
3941 * cleanup bogus pages, restoring the originals
3944 if (m == bogus_page) {
3945 bogus = bogusflag = 1;
3946 m = vm_page_lookup(obj, OFF_TO_IDX(foff));
3948 panic("biodone: page disappeared!");
3951 KASSERT(OFF_TO_IDX(foff) == m->pindex,
3952 ("biodone_finish: foff(%jd)/pindex(%ju) mismatch",
3953 (intmax_t)foff, (uintmax_t)m->pindex));
3956 * In the write case, the valid and clean bits are
3957 * already changed correctly ( see bdwrite() ), so we
3958 * only need to do this here in the read case.
3960 if ((bp->b_iocmd == BIO_READ) && !bogusflag && resid > 0) {
3961 KASSERT((m->dirty & vm_page_bits(foff &
3962 PAGE_MASK, resid)) == 0, ("bufdone_finish:"
3963 " page %p has unexpected dirty bits", m));
3964 vfs_page_set_valid(bp, foff, m);
3968 vm_object_pip_subtract(obj, 1);
3969 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK;
3972 vm_object_pip_wakeupn(obj, 0);
3973 VM_OBJECT_WUNLOCK(obj);
3974 if (bogus && buf_mapped(bp)) {
3975 BUF_CHECK_MAPPED(bp);
3976 pmap_qenter(trunc_page((vm_offset_t)bp->b_data),
3977 bp->b_pages, bp->b_npages);
3982 * For asynchronous completions, release the buffer now. The brelse
3983 * will do a wakeup there if necessary - so no need to do a wakeup
3984 * here in the async case. The sync case always needs to do a wakeup.
3987 if (bp->b_flags & B_ASYNC) {
3988 if ((bp->b_flags & (B_NOCACHE | B_INVAL | B_RELBUF)) || (bp->b_ioflags & BIO_ERROR))
3997 * This routine is called in lieu of iodone in the case of
3998 * incomplete I/O. This keeps the busy status for pages
4002 vfs_unbusy_pages(struct buf *bp)
4008 runningbufwakeup(bp);
4009 if (!(bp->b_flags & B_VMIO))
4012 obj = bp->b_bufobj->bo_object;
4013 VM_OBJECT_WLOCK(obj);
4014 for (i = 0; i < bp->b_npages; i++) {
4016 if (m == bogus_page) {
4017 m = vm_page_lookup(obj, OFF_TO_IDX(bp->b_offset) + i);
4019 panic("vfs_unbusy_pages: page missing\n");
4021 if (buf_mapped(bp)) {
4022 BUF_CHECK_MAPPED(bp);
4023 pmap_qenter(trunc_page((vm_offset_t)bp->b_data),
4024 bp->b_pages, bp->b_npages);
4026 BUF_CHECK_UNMAPPED(bp);
4028 vm_object_pip_subtract(obj, 1);
4031 vm_object_pip_wakeupn(obj, 0);
4032 VM_OBJECT_WUNLOCK(obj);
4036 * vfs_page_set_valid:
4038 * Set the valid bits in a page based on the supplied offset. The
4039 * range is restricted to the buffer's size.
4041 * This routine is typically called after a read completes.
4044 vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, vm_page_t m)
4049 * Compute the end offset, eoff, such that [off, eoff) does not span a
4050 * page boundary and eoff is not greater than the end of the buffer.
4051 * The end of the buffer, in this case, is our file EOF, not the
4052 * allocation size of the buffer.
4054 eoff = (off + PAGE_SIZE) & ~(vm_ooffset_t)PAGE_MASK;
4055 if (eoff > bp->b_offset + bp->b_bcount)
4056 eoff = bp->b_offset + bp->b_bcount;
4059 * Set valid range. This is typically the entire buffer and thus the
4063 vm_page_set_valid_range(m, off & PAGE_MASK, eoff - off);
4067 * vfs_page_set_validclean:
4069 * Set the valid bits and clear the dirty bits in a page based on the
4070 * supplied offset. The range is restricted to the buffer's size.
4073 vfs_page_set_validclean(struct buf *bp, vm_ooffset_t off, vm_page_t m)
4075 vm_ooffset_t soff, eoff;
4078 * Start and end offsets in buffer. eoff - soff may not cross a
4079 * page boundry or cross the end of the buffer. The end of the
4080 * buffer, in this case, is our file EOF, not the allocation size
4084 eoff = (off + PAGE_SIZE) & ~(off_t)PAGE_MASK;
4085 if (eoff > bp->b_offset + bp->b_bcount)
4086 eoff = bp->b_offset + bp->b_bcount;
4089 * Set valid range. This is typically the entire buffer and thus the
4093 vm_page_set_validclean(
4095 (vm_offset_t) (soff & PAGE_MASK),
4096 (vm_offset_t) (eoff - soff)
4102 * Ensure that all buffer pages are not exclusive busied. If any page is
4103 * exclusive busy, drain it.
4106 vfs_drain_busy_pages(struct buf *bp)
4111 VM_OBJECT_ASSERT_WLOCKED(bp->b_bufobj->bo_object);
4113 for (i = 0; i < bp->b_npages; i++) {
4115 if (vm_page_xbusied(m)) {
4116 for (; last_busied < i; last_busied++)
4117 vm_page_sbusy(bp->b_pages[last_busied]);
4118 while (vm_page_xbusied(m)) {
4120 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object);
4121 vm_page_busy_sleep(m, "vbpage");
4122 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object);
4126 for (i = 0; i < last_busied; i++)
4127 vm_page_sunbusy(bp->b_pages[i]);
4131 * This routine is called before a device strategy routine.
4132 * It is used to tell the VM system that paging I/O is in
4133 * progress, and treat the pages associated with the buffer
4134 * almost as being exclusive busy. Also the object paging_in_progress
4135 * flag is handled to make sure that the object doesn't become
4138 * Since I/O has not been initiated yet, certain buffer flags
4139 * such as BIO_ERROR or B_INVAL may be in an inconsistant state
4140 * and should be ignored.
4143 vfs_busy_pages(struct buf *bp, int clear_modify)
4150 if (!(bp->b_flags & B_VMIO))
4153 obj = bp->b_bufobj->bo_object;
4154 foff = bp->b_offset;
4155 KASSERT(bp->b_offset != NOOFFSET,
4156 ("vfs_busy_pages: no buffer offset"));
4157 VM_OBJECT_WLOCK(obj);
4158 vfs_drain_busy_pages(bp);
4159 if (bp->b_bufsize != 0)
4160 vfs_setdirty_locked_object(bp);
4162 for (i = 0; i < bp->b_npages; i++) {
4165 if ((bp->b_flags & B_CLUSTER) == 0) {
4166 vm_object_pip_add(obj, 1);
4170 * When readying a buffer for a read ( i.e
4171 * clear_modify == 0 ), it is important to do
4172 * bogus_page replacement for valid pages in
4173 * partially instantiated buffers. Partially
4174 * instantiated buffers can, in turn, occur when
4175 * reconstituting a buffer from its VM backing store
4176 * base. We only have to do this if B_CACHE is
4177 * clear ( which causes the I/O to occur in the
4178 * first place ). The replacement prevents the read
4179 * I/O from overwriting potentially dirty VM-backed
4180 * pages. XXX bogus page replacement is, uh, bogus.
4181 * It may not work properly with small-block devices.
4182 * We need to find a better way.
4185 pmap_remove_write(m);
4186 vfs_page_set_validclean(bp, foff, m);
4187 } else if (m->valid == VM_PAGE_BITS_ALL &&
4188 (bp->b_flags & B_CACHE) == 0) {
4189 bp->b_pages[i] = bogus_page;
4192 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK;
4194 VM_OBJECT_WUNLOCK(obj);
4195 if (bogus && buf_mapped(bp)) {
4196 BUF_CHECK_MAPPED(bp);
4197 pmap_qenter(trunc_page((vm_offset_t)bp->b_data),
4198 bp->b_pages, bp->b_npages);
4203 * vfs_bio_set_valid:
4205 * Set the range within the buffer to valid. The range is
4206 * relative to the beginning of the buffer, b_offset. Note that
4207 * b_offset itself may be offset from the beginning of the first
4211 vfs_bio_set_valid(struct buf *bp, int base, int size)
4216 if (!(bp->b_flags & B_VMIO))
4220 * Fixup base to be relative to beginning of first page.
4221 * Set initial n to be the maximum number of bytes in the
4222 * first page that can be validated.
4224 base += (bp->b_offset & PAGE_MASK);
4225 n = PAGE_SIZE - (base & PAGE_MASK);
4227 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object);
4228 for (i = base / PAGE_SIZE; size > 0 && i < bp->b_npages; ++i) {
4232 vm_page_set_valid_range(m, base & PAGE_MASK, n);
4237 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object);
4243 * If the specified buffer is a non-VMIO buffer, clear the entire
4244 * buffer. If the specified buffer is a VMIO buffer, clear and
4245 * validate only the previously invalid portions of the buffer.
4246 * This routine essentially fakes an I/O, so we need to clear
4247 * BIO_ERROR and B_INVAL.
4249 * Note that while we only theoretically need to clear through b_bcount,
4250 * we go ahead and clear through b_bufsize.
4253 vfs_bio_clrbuf(struct buf *bp)
4255 int i, j, mask, sa, ea, slide;
4257 if ((bp->b_flags & (B_VMIO | B_MALLOC)) != B_VMIO) {
4261 bp->b_flags &= ~B_INVAL;
4262 bp->b_ioflags &= ~BIO_ERROR;
4263 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object);
4264 if ((bp->b_npages == 1) && (bp->b_bufsize < PAGE_SIZE) &&
4265 (bp->b_offset & PAGE_MASK) == 0) {
4266 if (bp->b_pages[0] == bogus_page)
4268 mask = (1 << (bp->b_bufsize / DEV_BSIZE)) - 1;
4269 VM_OBJECT_ASSERT_WLOCKED(bp->b_pages[0]->object);
4270 if ((bp->b_pages[0]->valid & mask) == mask)
4272 if ((bp->b_pages[0]->valid & mask) == 0) {
4273 pmap_zero_page_area(bp->b_pages[0], 0, bp->b_bufsize);
4274 bp->b_pages[0]->valid |= mask;
4278 sa = bp->b_offset & PAGE_MASK;
4280 for (i = 0; i < bp->b_npages; i++, sa = 0) {
4281 slide = imin(slide + PAGE_SIZE, bp->b_offset + bp->b_bufsize);
4282 ea = slide & PAGE_MASK;
4285 if (bp->b_pages[i] == bogus_page)
4288 mask = ((1 << ((ea - sa) / DEV_BSIZE)) - 1) << j;
4289 VM_OBJECT_ASSERT_WLOCKED(bp->b_pages[i]->object);
4290 if ((bp->b_pages[i]->valid & mask) == mask)
4292 if ((bp->b_pages[i]->valid & mask) == 0)
4293 pmap_zero_page_area(bp->b_pages[i], sa, ea - sa);
4295 for (; sa < ea; sa += DEV_BSIZE, j++) {
4296 if ((bp->b_pages[i]->valid & (1 << j)) == 0) {
4297 pmap_zero_page_area(bp->b_pages[i],
4302 bp->b_pages[i]->valid |= mask;
4305 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object);
4310 vfs_bio_bzero_buf(struct buf *bp, int base, int size)
4315 if (buf_mapped(bp)) {
4316 BUF_CHECK_MAPPED(bp);
4317 bzero(bp->b_data + base, size);
4319 BUF_CHECK_UNMAPPED(bp);
4320 n = PAGE_SIZE - (base & PAGE_MASK);
4321 for (i = base / PAGE_SIZE; size > 0 && i < bp->b_npages; ++i) {
4325 pmap_zero_page_area(m, base & PAGE_MASK, n);
4334 * vm_hold_load_pages and vm_hold_free_pages get pages into
4335 * a buffers address space. The pages are anonymous and are
4336 * not associated with a file object.
4339 vm_hold_load_pages(struct buf *bp, vm_offset_t from, vm_offset_t to)
4345 BUF_CHECK_MAPPED(bp);
4347 to = round_page(to);
4348 from = round_page(from);
4349 index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT;
4351 for (pg = from; pg < to; pg += PAGE_SIZE, index++) {
4354 * note: must allocate system pages since blocking here
4355 * could interfere with paging I/O, no matter which
4358 p = vm_page_alloc(NULL, 0, VM_ALLOC_SYSTEM | VM_ALLOC_NOOBJ |
4359 VM_ALLOC_WIRED | VM_ALLOC_COUNT((to - pg) >> PAGE_SHIFT));
4364 pmap_qenter(pg, &p, 1);
4365 bp->b_pages[index] = p;
4367 bp->b_npages = index;
4370 /* Return pages associated with this buf to the vm system */
4372 vm_hold_free_pages(struct buf *bp, int newbsize)
4376 int index, newnpages;
4378 BUF_CHECK_MAPPED(bp);
4380 from = round_page((vm_offset_t)bp->b_data + newbsize);
4381 newnpages = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT;
4382 if (bp->b_npages > newnpages)
4383 pmap_qremove(from, bp->b_npages - newnpages);
4384 for (index = newnpages; index < bp->b_npages; index++) {
4385 p = bp->b_pages[index];
4386 bp->b_pages[index] = NULL;
4387 if (vm_page_sbusied(p))
4388 printf("vm_hold_free_pages: blkno: %jd, lblkno: %jd\n",
4389 (intmax_t)bp->b_blkno, (intmax_t)bp->b_lblkno);
4392 atomic_subtract_int(&vm_cnt.v_wire_count, 1);
4394 bp->b_npages = newnpages;
4398 * Map an IO request into kernel virtual address space.
4400 * All requests are (re)mapped into kernel VA space.
4401 * Notice that we use b_bufsize for the size of the buffer
4402 * to be mapped. b_bcount might be modified by the driver.
4404 * Note that even if the caller determines that the address space should
4405 * be valid, a race or a smaller-file mapped into a larger space may
4406 * actually cause vmapbuf() to fail, so all callers of vmapbuf() MUST
4407 * check the return value.
4409 * This function only works with pager buffers.
4412 vmapbuf(struct buf *bp, int mapbuf)
4417 if (bp->b_bufsize < 0)
4419 prot = VM_PROT_READ;
4420 if (bp->b_iocmd == BIO_READ)
4421 prot |= VM_PROT_WRITE; /* Less backwards than it looks */
4422 if ((pidx = vm_fault_quick_hold_pages(&curproc->p_vmspace->vm_map,
4423 (vm_offset_t)bp->b_data, bp->b_bufsize, prot, bp->b_pages,
4424 btoc(MAXPHYS))) < 0)
4426 bp->b_npages = pidx;
4427 bp->b_offset = ((vm_offset_t)bp->b_data) & PAGE_MASK;
4428 if (mapbuf || !unmapped_buf_allowed) {
4429 pmap_qenter((vm_offset_t)bp->b_kvabase, bp->b_pages, pidx);
4430 bp->b_data = bp->b_kvabase + bp->b_offset;
4432 bp->b_data = unmapped_buf;
4437 * Free the io map PTEs associated with this IO operation.
4438 * We also invalidate the TLB entries and restore the original b_addr.
4440 * This function only works with pager buffers.
4443 vunmapbuf(struct buf *bp)
4447 npages = bp->b_npages;
4449 pmap_qremove(trunc_page((vm_offset_t)bp->b_data), npages);
4450 vm_page_unhold_pages(bp->b_pages, npages);
4452 bp->b_data = unmapped_buf;
4456 bdone(struct buf *bp)
4460 mtxp = mtx_pool_find(mtxpool_sleep, bp);
4462 bp->b_flags |= B_DONE;
4468 bwait(struct buf *bp, u_char pri, const char *wchan)
4472 mtxp = mtx_pool_find(mtxpool_sleep, bp);
4474 while ((bp->b_flags & B_DONE) == 0)
4475 msleep(bp, mtxp, pri, wchan, 0);
4480 bufsync(struct bufobj *bo, int waitfor)
4483 return (VOP_FSYNC(bo->__bo_vnode, waitfor, curthread));
4487 bufstrategy(struct bufobj *bo, struct buf *bp)
4493 KASSERT(vp == bo->bo_private, ("Inconsistent vnode bufstrategy"));
4494 KASSERT(vp->v_type != VCHR && vp->v_type != VBLK,
4495 ("Wrong vnode in bufstrategy(bp=%p, vp=%p)", bp, vp));
4496 i = VOP_STRATEGY(vp, bp);
4497 KASSERT(i == 0, ("VOP_STRATEGY failed bp=%p vp=%p", bp, bp->b_vp));
4501 bufobj_wrefl(struct bufobj *bo)
4504 KASSERT(bo != NULL, ("NULL bo in bufobj_wref"));
4505 ASSERT_BO_WLOCKED(bo);
4510 bufobj_wref(struct bufobj *bo)
4513 KASSERT(bo != NULL, ("NULL bo in bufobj_wref"));
4520 bufobj_wdrop(struct bufobj *bo)
4523 KASSERT(bo != NULL, ("NULL bo in bufobj_wdrop"));
4525 KASSERT(bo->bo_numoutput > 0, ("bufobj_wdrop non-positive count"));
4526 if ((--bo->bo_numoutput == 0) && (bo->bo_flag & BO_WWAIT)) {
4527 bo->bo_flag &= ~BO_WWAIT;
4528 wakeup(&bo->bo_numoutput);
4534 bufobj_wwait(struct bufobj *bo, int slpflag, int timeo)
4538 KASSERT(bo != NULL, ("NULL bo in bufobj_wwait"));
4539 ASSERT_BO_WLOCKED(bo);
4541 while (bo->bo_numoutput) {
4542 bo->bo_flag |= BO_WWAIT;
4543 error = msleep(&bo->bo_numoutput, BO_LOCKPTR(bo),
4544 slpflag | (PRIBIO + 1), "bo_wwait", timeo);
4552 bpin(struct buf *bp)
4556 mtxp = mtx_pool_find(mtxpool_sleep, bp);
4563 bunpin(struct buf *bp)
4567 mtxp = mtx_pool_find(mtxpool_sleep, bp);
4569 if (--bp->b_pin_count == 0)
4575 bunpin_wait(struct buf *bp)
4579 mtxp = mtx_pool_find(mtxpool_sleep, bp);
4581 while (bp->b_pin_count > 0)
4582 msleep(bp, mtxp, PRIBIO, "bwunpin", 0);
4587 * Set bio_data or bio_ma for struct bio from the struct buf.
4590 bdata2bio(struct buf *bp, struct bio *bip)
4593 if (!buf_mapped(bp)) {
4594 KASSERT(unmapped_buf_allowed, ("unmapped"));
4595 bip->bio_ma = bp->b_pages;
4596 bip->bio_ma_n = bp->b_npages;
4597 bip->bio_data = unmapped_buf;
4598 bip->bio_ma_offset = (vm_offset_t)bp->b_offset & PAGE_MASK;
4599 bip->bio_flags |= BIO_UNMAPPED;
4600 KASSERT(round_page(bip->bio_ma_offset + bip->bio_length) /
4601 PAGE_SIZE == bp->b_npages,
4602 ("Buffer %p too short: %d %lld %d", bp, bip->bio_ma_offset,
4603 (long long)bip->bio_length, bip->bio_ma_n));
4605 bip->bio_data = bp->b_data;
4610 #include "opt_ddb.h"
4612 #include <ddb/ddb.h>
4614 /* DDB command to show buffer data */
4615 DB_SHOW_COMMAND(buffer, db_show_buffer)
4618 struct buf *bp = (struct buf *)addr;
4621 db_printf("usage: show buffer <addr>\n");
4625 db_printf("buf at %p\n", bp);
4626 db_printf("b_flags = 0x%b, b_xflags=0x%b, b_vflags=0x%b\n",
4627 (u_int)bp->b_flags, PRINT_BUF_FLAGS, (u_int)bp->b_xflags,
4628 PRINT_BUF_XFLAGS, (u_int)bp->b_vflags, PRINT_BUF_VFLAGS);
4630 "b_error = %d, b_bufsize = %ld, b_bcount = %ld, b_resid = %ld\n"
4631 "b_bufobj = (%p), b_data = %p, b_blkno = %jd, b_lblkno = %jd, "
4633 bp->b_error, bp->b_bufsize, bp->b_bcount, bp->b_resid,
4634 bp->b_bufobj, bp->b_data, (intmax_t)bp->b_blkno,
4635 (intmax_t)bp->b_lblkno, bp->b_dep.lh_first);
4636 db_printf("b_kvabase = %p, b_kvasize = %d\n",
4637 bp->b_kvabase, bp->b_kvasize);
4640 db_printf("b_npages = %d, pages(OBJ, IDX, PA): ", bp->b_npages);
4641 for (i = 0; i < bp->b_npages; i++) {
4644 db_printf("(%p, 0x%lx, 0x%lx)", (void *)m->object,
4645 (u_long)m->pindex, (u_long)VM_PAGE_TO_PHYS(m));
4646 if ((i + 1) < bp->b_npages)
4652 BUF_LOCKPRINTINFO(bp);
4655 DB_SHOW_COMMAND(lockedbufs, lockedbufs)
4660 for (i = 0; i < nbuf; i++) {
4662 if (BUF_ISLOCKED(bp)) {
4663 db_show_buffer((uintptr_t)bp, 1, 0, NULL);
4669 DB_SHOW_COMMAND(vnodebufs, db_show_vnodebufs)
4675 db_printf("usage: show vnodebufs <addr>\n");
4678 vp = (struct vnode *)addr;
4679 db_printf("Clean buffers:\n");
4680 TAILQ_FOREACH(bp, &vp->v_bufobj.bo_clean.bv_hd, b_bobufs) {
4681 db_show_buffer((uintptr_t)bp, 1, 0, NULL);
4684 db_printf("Dirty buffers:\n");
4685 TAILQ_FOREACH(bp, &vp->v_bufobj.bo_dirty.bv_hd, b_bobufs) {
4686 db_show_buffer((uintptr_t)bp, 1, 0, NULL);
4691 DB_COMMAND(countfreebufs, db_coundfreebufs)
4694 int i, used = 0, nfree = 0;
4697 db_printf("usage: countfreebufs\n");
4701 for (i = 0; i < nbuf; i++) {
4703 if ((bp->b_flags & B_INFREECNT) != 0)
4709 db_printf("Counted %d free, %d used (%d tot)\n", nfree, used,
4711 db_printf("numfreebuffers is %d\n", numfreebuffers);