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/racct.h>
65 #include <sys/resourcevar.h>
66 #include <sys/rwlock.h>
68 #include <sys/sysctl.h>
69 #include <sys/sysproto.h>
71 #include <sys/vmmeter.h>
72 #include <sys/vnode.h>
73 #include <sys/watchdog.h>
74 #include <geom/geom.h>
76 #include <vm/vm_param.h>
77 #include <vm/vm_kern.h>
78 #include <vm/vm_object.h>
79 #include <vm/vm_page.h>
80 #include <vm/vm_pageout.h>
81 #include <vm/vm_pager.h>
82 #include <vm/vm_extern.h>
83 #include <vm/vm_map.h>
84 #include <vm/swap_pager.h>
85 #include "opt_compat.h"
88 static MALLOC_DEFINE(M_BIOBUF, "biobuf", "BIO buffer");
90 struct bio_ops bioops; /* I/O operation notification */
92 struct buf_ops buf_ops_bio = {
93 .bop_name = "buf_ops_bio",
94 .bop_write = bufwrite,
95 .bop_strategy = bufstrategy,
97 .bop_bdflush = bufbdflush,
100 static struct buf *buf; /* buffer header pool */
101 extern struct buf *swbuf; /* Swap buffer header pool. */
102 caddr_t unmapped_buf;
104 /* Used below and for softdep flushing threads in ufs/ffs/ffs_softdep.c */
105 struct proc *bufdaemonproc;
106 struct proc *bufspacedaemonproc;
108 static int inmem(struct vnode *vp, daddr_t blkno);
109 static void vm_hold_free_pages(struct buf *bp, int newbsize);
110 static void vm_hold_load_pages(struct buf *bp, vm_offset_t from,
112 static void vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, vm_page_t m);
113 static void vfs_page_set_validclean(struct buf *bp, vm_ooffset_t off,
115 static void vfs_clean_pages_dirty_buf(struct buf *bp);
116 static void vfs_setdirty_locked_object(struct buf *bp);
117 static void vfs_vmio_invalidate(struct buf *bp);
118 static void vfs_vmio_truncate(struct buf *bp, int npages);
119 static void vfs_vmio_extend(struct buf *bp, int npages, int size);
120 static int vfs_bio_clcheck(struct vnode *vp, int size,
121 daddr_t lblkno, daddr_t blkno);
122 static void breada(struct vnode *, daddr_t *, int *, int, struct ucred *, int,
123 void (*)(struct buf *));
124 static int buf_flush(struct vnode *vp, int);
125 static int buf_recycle(bool);
126 static int buf_scan(bool);
127 static int flushbufqueues(struct vnode *, int, int);
128 static void buf_daemon(void);
129 static void bremfreel(struct buf *bp);
130 static __inline void bd_wakeup(void);
131 static int sysctl_runningspace(SYSCTL_HANDLER_ARGS);
132 static void bufkva_reclaim(vmem_t *, int);
133 static void bufkva_free(struct buf *);
134 static int buf_import(void *, void **, int, int);
135 static void buf_release(void *, void **, int);
136 static void maxbcachebuf_adjust(void);
138 #if defined(COMPAT_FREEBSD4) || defined(COMPAT_FREEBSD5) || \
139 defined(COMPAT_FREEBSD6) || defined(COMPAT_FREEBSD7)
140 static int sysctl_bufspace(SYSCTL_HANDLER_ARGS);
143 int vmiodirenable = TRUE;
144 SYSCTL_INT(_vfs, OID_AUTO, vmiodirenable, CTLFLAG_RW, &vmiodirenable, 0,
145 "Use the VM system for directory writes");
146 long runningbufspace;
147 SYSCTL_LONG(_vfs, OID_AUTO, runningbufspace, CTLFLAG_RD, &runningbufspace, 0,
148 "Amount of presently outstanding async buffer io");
149 static long bufspace;
150 #if defined(COMPAT_FREEBSD4) || defined(COMPAT_FREEBSD5) || \
151 defined(COMPAT_FREEBSD6) || defined(COMPAT_FREEBSD7)
152 SYSCTL_PROC(_vfs, OID_AUTO, bufspace, CTLTYPE_LONG|CTLFLAG_MPSAFE|CTLFLAG_RD,
153 &bufspace, 0, sysctl_bufspace, "L", "Virtual memory used for buffers");
155 SYSCTL_LONG(_vfs, OID_AUTO, bufspace, CTLFLAG_RD, &bufspace, 0,
156 "Physical memory used for buffers");
158 static long bufkvaspace;
159 SYSCTL_LONG(_vfs, OID_AUTO, bufkvaspace, CTLFLAG_RD, &bufkvaspace, 0,
160 "Kernel virtual memory used for buffers");
161 static long maxbufspace;
162 SYSCTL_LONG(_vfs, OID_AUTO, maxbufspace, CTLFLAG_RW, &maxbufspace, 0,
163 "Maximum allowed value of bufspace (including metadata)");
164 static long bufmallocspace;
165 SYSCTL_LONG(_vfs, OID_AUTO, bufmallocspace, CTLFLAG_RD, &bufmallocspace, 0,
166 "Amount of malloced memory for buffers");
167 static long maxbufmallocspace;
168 SYSCTL_LONG(_vfs, OID_AUTO, maxmallocbufspace, CTLFLAG_RW, &maxbufmallocspace,
169 0, "Maximum amount of malloced memory for buffers");
170 static long lobufspace;
171 SYSCTL_LONG(_vfs, OID_AUTO, lobufspace, CTLFLAG_RW, &lobufspace, 0,
172 "Minimum amount of buffers we want to have");
174 SYSCTL_LONG(_vfs, OID_AUTO, hibufspace, CTLFLAG_RW, &hibufspace, 0,
175 "Maximum allowed value of bufspace (excluding metadata)");
177 SYSCTL_LONG(_vfs, OID_AUTO, bufspacethresh, CTLFLAG_RW, &bufspacethresh,
178 0, "Bufspace consumed before waking the daemon to free some");
179 static int buffreekvacnt;
180 SYSCTL_INT(_vfs, OID_AUTO, buffreekvacnt, CTLFLAG_RW, &buffreekvacnt, 0,
181 "Number of times we have freed the KVA space from some buffer");
182 static int bufdefragcnt;
183 SYSCTL_INT(_vfs, OID_AUTO, bufdefragcnt, CTLFLAG_RW, &bufdefragcnt, 0,
184 "Number of times we have had to repeat buffer allocation to defragment");
185 static long lorunningspace;
186 SYSCTL_PROC(_vfs, OID_AUTO, lorunningspace, CTLTYPE_LONG | CTLFLAG_MPSAFE |
187 CTLFLAG_RW, &lorunningspace, 0, sysctl_runningspace, "L",
188 "Minimum preferred space used for in-progress I/O");
189 static long hirunningspace;
190 SYSCTL_PROC(_vfs, OID_AUTO, hirunningspace, CTLTYPE_LONG | CTLFLAG_MPSAFE |
191 CTLFLAG_RW, &hirunningspace, 0, sysctl_runningspace, "L",
192 "Maximum amount of space to use for in-progress I/O");
193 int dirtybufferflushes;
194 SYSCTL_INT(_vfs, OID_AUTO, dirtybufferflushes, CTLFLAG_RW, &dirtybufferflushes,
195 0, "Number of bdwrite to bawrite conversions to limit dirty buffers");
197 SYSCTL_INT(_vfs, OID_AUTO, bdwriteskip, CTLFLAG_RW, &bdwriteskip,
198 0, "Number of buffers supplied to bdwrite with snapshot deadlock risk");
199 int altbufferflushes;
200 SYSCTL_INT(_vfs, OID_AUTO, altbufferflushes, CTLFLAG_RW, &altbufferflushes,
201 0, "Number of fsync flushes to limit dirty buffers");
202 static int recursiveflushes;
203 SYSCTL_INT(_vfs, OID_AUTO, recursiveflushes, CTLFLAG_RW, &recursiveflushes,
204 0, "Number of flushes skipped due to being recursive");
205 static int numdirtybuffers;
206 SYSCTL_INT(_vfs, OID_AUTO, numdirtybuffers, CTLFLAG_RD, &numdirtybuffers, 0,
207 "Number of buffers that are dirty (has unwritten changes) at the moment");
208 static int lodirtybuffers;
209 SYSCTL_INT(_vfs, OID_AUTO, lodirtybuffers, CTLFLAG_RW, &lodirtybuffers, 0,
210 "How many buffers we want to have free before bufdaemon can sleep");
211 static int hidirtybuffers;
212 SYSCTL_INT(_vfs, OID_AUTO, hidirtybuffers, CTLFLAG_RW, &hidirtybuffers, 0,
213 "When the number of dirty buffers is considered severe");
215 SYSCTL_INT(_vfs, OID_AUTO, dirtybufthresh, CTLFLAG_RW, &dirtybufthresh,
216 0, "Number of bdwrite to bawrite conversions to clear dirty buffers");
217 static int numfreebuffers;
218 SYSCTL_INT(_vfs, OID_AUTO, numfreebuffers, CTLFLAG_RD, &numfreebuffers, 0,
219 "Number of free buffers");
220 static int lofreebuffers;
221 SYSCTL_INT(_vfs, OID_AUTO, lofreebuffers, CTLFLAG_RW, &lofreebuffers, 0,
222 "Target number of free buffers");
223 static int hifreebuffers;
224 SYSCTL_INT(_vfs, OID_AUTO, hifreebuffers, CTLFLAG_RW, &hifreebuffers, 0,
225 "Threshold for clean buffer recycling");
226 static int getnewbufcalls;
227 SYSCTL_INT(_vfs, OID_AUTO, getnewbufcalls, CTLFLAG_RW, &getnewbufcalls, 0,
228 "Number of calls to getnewbuf");
229 static int getnewbufrestarts;
230 SYSCTL_INT(_vfs, OID_AUTO, getnewbufrestarts, CTLFLAG_RW, &getnewbufrestarts, 0,
231 "Number of times getnewbuf has had to restart a buffer acquisition");
232 static int mappingrestarts;
233 SYSCTL_INT(_vfs, OID_AUTO, mappingrestarts, CTLFLAG_RW, &mappingrestarts, 0,
234 "Number of times getblk has had to restart a buffer mapping for "
236 static int numbufallocfails;
237 SYSCTL_INT(_vfs, OID_AUTO, numbufallocfails, CTLFLAG_RW, &numbufallocfails, 0,
238 "Number of times buffer allocations failed");
239 static int flushbufqtarget = 100;
240 SYSCTL_INT(_vfs, OID_AUTO, flushbufqtarget, CTLFLAG_RW, &flushbufqtarget, 0,
241 "Amount of work to do in flushbufqueues when helping bufdaemon");
242 static long notbufdflushes;
243 SYSCTL_LONG(_vfs, OID_AUTO, notbufdflushes, CTLFLAG_RD, ¬bufdflushes, 0,
244 "Number of dirty buffer flushes done by the bufdaemon helpers");
245 static long barrierwrites;
246 SYSCTL_LONG(_vfs, OID_AUTO, barrierwrites, CTLFLAG_RW, &barrierwrites, 0,
247 "Number of barrier writes");
248 SYSCTL_INT(_vfs, OID_AUTO, unmapped_buf_allowed, CTLFLAG_RD,
249 &unmapped_buf_allowed, 0,
250 "Permit the use of the unmapped i/o");
251 int maxbcachebuf = MAXBCACHEBUF;
252 SYSCTL_INT(_vfs, OID_AUTO, maxbcachebuf, CTLFLAG_RDTUN, &maxbcachebuf, 0,
253 "Maximum size of a buffer cache block");
256 * This lock synchronizes access to bd_request.
258 static struct mtx_padalign __exclusive_cache_line bdlock;
261 * This lock protects the runningbufreq and synchronizes runningbufwakeup and
262 * waitrunningbufspace().
264 static struct mtx_padalign __exclusive_cache_line rbreqlock;
267 * Lock that protects needsbuffer and the sleeps/wakeups surrounding it.
269 static struct rwlock_padalign __exclusive_cache_line nblock;
272 * Lock that protects bdirtywait.
274 static struct mtx_padalign __exclusive_cache_line bdirtylock;
277 * Wakeup point for bufdaemon, as well as indicator of whether it is already
278 * active. Set to 1 when the bufdaemon is already "on" the queue, 0 when it
281 static int bd_request;
284 * Request/wakeup point for the bufspace daemon.
286 static int bufspace_request;
289 * Request for the buf daemon to write more buffers than is indicated by
290 * lodirtybuf. This may be necessary to push out excess dependencies or
291 * defragment the address space where a simple count of the number of dirty
292 * buffers is insufficient to characterize the demand for flushing them.
294 static int bd_speedupreq;
297 * Synchronization (sleep/wakeup) variable for active buffer space requests.
298 * Set when wait starts, cleared prior to wakeup().
299 * Used in runningbufwakeup() and waitrunningbufspace().
301 static int runningbufreq;
304 * Synchronization (sleep/wakeup) variable for buffer requests.
305 * Can contain the VFS_BIO_NEED flags defined below; setting/clearing is done
307 * Used in numdirtywakeup(), bufspace_wakeup(), bwillwrite(),
308 * getnewbuf(), and getblk().
310 static volatile int needsbuffer;
313 * Synchronization for bwillwrite() waiters.
315 static int bdirtywait;
318 * Definitions for the buffer free lists.
320 #define QUEUE_NONE 0 /* on no queue */
321 #define QUEUE_EMPTY 1 /* empty buffer headers */
322 #define QUEUE_DIRTY 2 /* B_DELWRI buffers */
323 #define QUEUE_CLEAN 3 /* non-B_DELWRI buffers */
324 #define QUEUE_SENTINEL 1024 /* not an queue index, but mark for sentinel */
326 /* Maximum number of clean buffer queues. */
327 #define CLEAN_QUEUES 16
329 /* Configured number of clean queues. */
330 static int clean_queues;
332 /* Maximum number of buffer queues. */
333 #define BUFFER_QUEUES (QUEUE_CLEAN + CLEAN_QUEUES)
335 /* Queues for free buffers with various properties */
336 static TAILQ_HEAD(bqueues, buf) bufqueues[BUFFER_QUEUES] = { { 0 } };
338 static int bq_len[BUFFER_QUEUES];
342 * Lock for each bufqueue
344 static struct mtx_padalign __exclusive_cache_line bqlocks[BUFFER_QUEUES];
347 * per-cpu empty buffer cache.
352 * Single global constant for BUF_WMESG, to avoid getting multiple references.
353 * buf_wmesg is referred from macros.
355 const char *buf_wmesg = BUF_WMESG;
358 sysctl_runningspace(SYSCTL_HANDLER_ARGS)
363 value = *(long *)arg1;
364 error = sysctl_handle_long(oidp, &value, 0, req);
365 if (error != 0 || req->newptr == NULL)
367 mtx_lock(&rbreqlock);
368 if (arg1 == &hirunningspace) {
369 if (value < lorunningspace)
372 hirunningspace = value;
374 KASSERT(arg1 == &lorunningspace,
375 ("%s: unknown arg1", __func__));
376 if (value > hirunningspace)
379 lorunningspace = value;
381 mtx_unlock(&rbreqlock);
385 #if defined(COMPAT_FREEBSD4) || defined(COMPAT_FREEBSD5) || \
386 defined(COMPAT_FREEBSD6) || defined(COMPAT_FREEBSD7)
388 sysctl_bufspace(SYSCTL_HANDLER_ARGS)
393 if (sizeof(int) == sizeof(long) || req->oldlen >= sizeof(long))
394 return (sysctl_handle_long(oidp, arg1, arg2, req));
395 lvalue = *(long *)arg1;
396 if (lvalue > INT_MAX)
397 /* On overflow, still write out a long to trigger ENOMEM. */
398 return (sysctl_handle_long(oidp, &lvalue, 0, req));
400 return (sysctl_handle_int(oidp, &ivalue, 0, req));
409 return ((atomic_fetchadd_int(&nextq, 1) % clean_queues) + QUEUE_CLEAN);
413 bqisclean(int qindex)
416 return (qindex >= QUEUE_CLEAN && qindex < QUEUE_CLEAN + CLEAN_QUEUES);
422 * Return the appropriate queue lock based on the index.
424 static inline struct mtx *
428 return (struct mtx *)&bqlocks[qindex];
434 * Wakeup any bwillwrite() waiters.
439 mtx_lock(&bdirtylock);
444 mtx_unlock(&bdirtylock);
450 * Decrement the numdirtybuffers count by one and wakeup any
451 * threads blocked in bwillwrite().
457 if (atomic_fetchadd_int(&numdirtybuffers, -1) ==
458 (lodirtybuffers + hidirtybuffers) / 2)
465 * Increment the numdirtybuffers count by one and wakeup the buf
473 * Only do the wakeup once as we cross the boundary. The
474 * buf daemon will keep running until the condition clears.
476 if (atomic_fetchadd_int(&numdirtybuffers, 1) ==
477 (lodirtybuffers + hidirtybuffers) / 2)
484 * Called when buffer space is potentially available for recovery.
485 * getnewbuf() will block on this flag when it is unable to free
486 * sufficient buffer space. Buffer space becomes recoverable when
487 * bp's get placed back in the queues.
490 bufspace_wakeup(void)
494 * If someone is waiting for bufspace, wake them up.
496 * Since needsbuffer is set prior to doing an additional queue
497 * scan it is safe to check for the flag prior to acquiring the
498 * lock. The thread that is preparing to scan again before
499 * blocking would discover the buf we released.
503 if (atomic_cmpset_int(&needsbuffer, 1, 0) == 1)
504 wakeup(__DEVOLATILE(void *, &needsbuffer));
510 * bufspace_daemonwakeup:
512 * Wakeup the daemon responsible for freeing clean bufs.
515 bufspace_daemonwakeup(void)
518 if (bufspace_request == 0) {
519 bufspace_request = 1;
520 wakeup(&bufspace_request);
528 * Adjust the reported bufspace for a KVA managed buffer, possibly
529 * waking any waiters.
532 bufspace_adjust(struct buf *bp, int bufsize)
537 KASSERT((bp->b_flags & B_MALLOC) == 0,
538 ("bufspace_adjust: malloc buf %p", bp));
539 diff = bufsize - bp->b_bufsize;
541 atomic_subtract_long(&bufspace, -diff);
544 space = atomic_fetchadd_long(&bufspace, diff);
545 /* Wake up the daemon on the transition. */
546 if (space < bufspacethresh && space + diff >= bufspacethresh)
547 bufspace_daemonwakeup();
549 bp->b_bufsize = bufsize;
555 * Reserve bufspace before calling allocbuf(). metadata has a
556 * different space limit than data.
559 bufspace_reserve(int size, bool metadata)
570 if (space + size > limit)
572 } while (atomic_cmpset_long(&bufspace, space, space + size) == 0);
574 /* Wake up the daemon on the transition. */
575 if (space < bufspacethresh && space + size >= bufspacethresh)
576 bufspace_daemonwakeup();
584 * Release reserved bufspace after bufspace_adjust() has consumed it.
587 bufspace_release(int size)
589 atomic_subtract_long(&bufspace, size);
596 * Wait for bufspace, acting as the buf daemon if a locked vnode is
597 * supplied. needsbuffer must be set in a safe fashion prior to
598 * polling for space. The operation must be re-tried on return.
601 bufspace_wait(struct vnode *vp, int gbflags, int slpflag, int slptimeo)
604 int error, fl, norunbuf;
606 if ((gbflags & GB_NOWAIT_BD) != 0)
611 while (needsbuffer != 0) {
612 if (vp != NULL && vp->v_type != VCHR &&
613 (td->td_pflags & TDP_BUFNEED) == 0) {
616 * getblk() is called with a vnode locked, and
617 * some majority of the dirty buffers may as
618 * well belong to the vnode. Flushing the
619 * buffers there would make a progress that
620 * cannot be achieved by the buf_daemon, that
621 * cannot lock the vnode.
623 norunbuf = ~(TDP_BUFNEED | TDP_NORUNNINGBUF) |
624 (td->td_pflags & TDP_NORUNNINGBUF);
627 * Play bufdaemon. The getnewbuf() function
628 * may be called while the thread owns lock
629 * for another dirty buffer for the same
630 * vnode, which makes it impossible to use
631 * VOP_FSYNC() there, due to the buffer lock
634 td->td_pflags |= TDP_BUFNEED | TDP_NORUNNINGBUF;
635 fl = buf_flush(vp, flushbufqtarget);
636 td->td_pflags &= norunbuf;
640 if (needsbuffer == 0)
643 error = rw_sleep(__DEVOLATILE(void *, &needsbuffer), &nblock,
644 (PRIBIO + 4) | slpflag, "newbuf", slptimeo);
655 * buffer space management daemon. Tries to maintain some marginal
656 * amount of free buffer space so that requesting processes neither
657 * block nor work to reclaim buffers.
660 bufspace_daemon(void)
663 kproc_suspend_check(bufspacedaemonproc);
666 * Free buffers from the clean queue until we meet our
669 * Theory of operation: The buffer cache is most efficient
670 * when some free buffer headers and space are always
671 * available to getnewbuf(). This daemon attempts to prevent
672 * the excessive blocking and synchronization associated
673 * with shortfall. It goes through three phases according
676 * 1) The daemon wakes up voluntarily once per-second
677 * during idle periods when the counters are below
678 * the wakeup thresholds (bufspacethresh, lofreebuffers).
680 * 2) The daemon wakes up as we cross the thresholds
681 * ahead of any potential blocking. This may bounce
682 * slightly according to the rate of consumption and
685 * 3) The daemon and consumers are starved for working
686 * clean buffers. This is the 'bufspace' sleep below
687 * which will inefficiently trade bufs with bqrelse
688 * until we return to condition 2.
690 while (bufspace > lobufspace ||
691 numfreebuffers < hifreebuffers) {
692 if (buf_recycle(false) != 0) {
693 atomic_set_int(&needsbuffer, 1);
694 if (buf_recycle(false) != 0) {
697 rw_sleep(__DEVOLATILE(void *,
698 &needsbuffer), &nblock,
699 PRIBIO|PDROP, "bufspace",
709 * Re-check our limits under the exclusive nblock.
712 if (bufspace < bufspacethresh &&
713 numfreebuffers > lofreebuffers) {
714 bufspace_request = 0;
715 rw_sleep(&bufspace_request, &nblock, PRIBIO|PDROP,
722 static struct kproc_desc bufspace_kp = {
727 SYSINIT(bufspacedaemon, SI_SUB_KTHREAD_BUF, SI_ORDER_FIRST, kproc_start,
733 * Adjust the reported bufspace for a malloc managed buffer, possibly
734 * waking any waiters.
737 bufmallocadjust(struct buf *bp, int bufsize)
741 KASSERT((bp->b_flags & B_MALLOC) != 0,
742 ("bufmallocadjust: non-malloc buf %p", bp));
743 diff = bufsize - bp->b_bufsize;
745 atomic_subtract_long(&bufmallocspace, -diff);
747 atomic_add_long(&bufmallocspace, diff);
748 bp->b_bufsize = bufsize;
754 * Wake up processes that are waiting on asynchronous writes to fall
755 * below lorunningspace.
761 mtx_lock(&rbreqlock);
764 wakeup(&runningbufreq);
766 mtx_unlock(&rbreqlock);
772 * Decrement the outstanding write count according.
775 runningbufwakeup(struct buf *bp)
779 bspace = bp->b_runningbufspace;
782 space = atomic_fetchadd_long(&runningbufspace, -bspace);
783 KASSERT(space >= bspace, ("runningbufspace underflow %ld %ld",
785 bp->b_runningbufspace = 0;
787 * Only acquire the lock and wakeup on the transition from exceeding
788 * the threshold to falling below it.
790 if (space < lorunningspace)
792 if (space - bspace > lorunningspace)
798 * waitrunningbufspace()
800 * runningbufspace is a measure of the amount of I/O currently
801 * running. This routine is used in async-write situations to
802 * prevent creating huge backups of pending writes to a device.
803 * Only asynchronous writes are governed by this function.
805 * This does NOT turn an async write into a sync write. It waits
806 * for earlier writes to complete and generally returns before the
807 * caller's write has reached the device.
810 waitrunningbufspace(void)
813 mtx_lock(&rbreqlock);
814 while (runningbufspace > hirunningspace) {
816 msleep(&runningbufreq, &rbreqlock, PVM, "wdrain", 0);
818 mtx_unlock(&rbreqlock);
823 * vfs_buf_test_cache:
825 * Called when a buffer is extended. This function clears the B_CACHE
826 * bit if the newly extended portion of the buffer does not contain
830 vfs_buf_test_cache(struct buf *bp, vm_ooffset_t foff, vm_offset_t off,
831 vm_offset_t size, vm_page_t m)
834 VM_OBJECT_ASSERT_LOCKED(m->object);
835 if (bp->b_flags & B_CACHE) {
836 int base = (foff + off) & PAGE_MASK;
837 if (vm_page_is_valid(m, base, size) == 0)
838 bp->b_flags &= ~B_CACHE;
842 /* Wake up the buffer daemon if necessary */
848 if (bd_request == 0) {
856 * Adjust the maxbcachbuf tunable.
859 maxbcachebuf_adjust(void)
864 * maxbcachebuf must be a power of 2 >= MAXBSIZE.
867 while (i * 2 <= maxbcachebuf)
870 if (maxbcachebuf < MAXBSIZE)
871 maxbcachebuf = MAXBSIZE;
872 if (maxbcachebuf > MAXPHYS)
873 maxbcachebuf = MAXPHYS;
874 if (bootverbose != 0 && maxbcachebuf != MAXBCACHEBUF)
875 printf("maxbcachebuf=%d\n", maxbcachebuf);
879 * bd_speedup - speedup the buffer cache flushing code
888 if (bd_speedupreq == 0 || bd_request == 0)
898 #define NSWBUF_MIN 16
902 #define TRANSIENT_DENOM 5
904 #define TRANSIENT_DENOM 10
908 * Calculating buffer cache scaling values and reserve space for buffer
909 * headers. This is called during low level kernel initialization and
910 * may be called more then once. We CANNOT write to the memory area
911 * being reserved at this time.
914 kern_vfs_bio_buffer_alloc(caddr_t v, long physmem_est)
917 long maxbuf, maxbuf_sz, buf_sz, biotmap_sz;
920 * physmem_est is in pages. Convert it to kilobytes (assumes
921 * PAGE_SIZE is >= 1K)
923 physmem_est = physmem_est * (PAGE_SIZE / 1024);
925 maxbcachebuf_adjust();
927 * The nominal buffer size (and minimum KVA allocation) is BKVASIZE.
928 * For the first 64MB of ram nominally allocate sufficient buffers to
929 * cover 1/4 of our ram. Beyond the first 64MB allocate additional
930 * buffers to cover 1/10 of our ram over 64MB. When auto-sizing
931 * the buffer cache we limit the eventual kva reservation to
934 * factor represents the 1/4 x ram conversion.
937 int factor = 4 * BKVASIZE / 1024;
940 if (physmem_est > 4096)
941 nbuf += min((physmem_est - 4096) / factor,
943 if (physmem_est > 65536)
944 nbuf += min((physmem_est - 65536) * 2 / (factor * 5),
945 32 * 1024 * 1024 / (factor * 5));
947 if (maxbcache && nbuf > maxbcache / BKVASIZE)
948 nbuf = maxbcache / BKVASIZE;
953 /* XXX Avoid unsigned long overflows later on with maxbufspace. */
954 maxbuf = (LONG_MAX / 3) / BKVASIZE;
957 printf("Warning: nbufs lowered from %d to %ld\n", nbuf,
963 * Ideal allocation size for the transient bio submap is 10%
964 * of the maximal space buffer map. This roughly corresponds
965 * to the amount of the buffer mapped for typical UFS load.
967 * Clip the buffer map to reserve space for the transient
968 * BIOs, if its extent is bigger than 90% (80% on i386) of the
969 * maximum buffer map extent on the platform.
971 * The fall-back to the maxbuf in case of maxbcache unset,
972 * allows to not trim the buffer KVA for the architectures
973 * with ample KVA space.
975 if (bio_transient_maxcnt == 0 && unmapped_buf_allowed) {
976 maxbuf_sz = maxbcache != 0 ? maxbcache : maxbuf * BKVASIZE;
977 buf_sz = (long)nbuf * BKVASIZE;
978 if (buf_sz < maxbuf_sz / TRANSIENT_DENOM *
979 (TRANSIENT_DENOM - 1)) {
981 * There is more KVA than memory. Do not
982 * adjust buffer map size, and assign the rest
983 * of maxbuf to transient map.
985 biotmap_sz = maxbuf_sz - buf_sz;
988 * Buffer map spans all KVA we could afford on
989 * this platform. Give 10% (20% on i386) of
990 * the buffer map to the transient bio map.
992 biotmap_sz = buf_sz / TRANSIENT_DENOM;
993 buf_sz -= biotmap_sz;
995 if (biotmap_sz / INT_MAX > MAXPHYS)
996 bio_transient_maxcnt = INT_MAX;
998 bio_transient_maxcnt = biotmap_sz / MAXPHYS;
1000 * Artificially limit to 1024 simultaneous in-flight I/Os
1001 * using the transient mapping.
1003 if (bio_transient_maxcnt > 1024)
1004 bio_transient_maxcnt = 1024;
1006 nbuf = buf_sz / BKVASIZE;
1010 * swbufs are used as temporary holders for I/O, such as paging I/O.
1011 * We have no less then 16 and no more then 256.
1013 nswbuf = min(nbuf / 4, 256);
1014 TUNABLE_INT_FETCH("kern.nswbuf", &nswbuf);
1015 if (nswbuf < NSWBUF_MIN)
1016 nswbuf = NSWBUF_MIN;
1019 * Reserve space for the buffer cache buffers
1022 v = (caddr_t)(swbuf + nswbuf);
1024 v = (caddr_t)(buf + nbuf);
1029 /* Initialize the buffer subsystem. Called before use of any buffers. */
1036 KASSERT(maxbcachebuf >= MAXBSIZE,
1037 ("maxbcachebuf (%d) must be >= MAXBSIZE (%d)\n", maxbcachebuf,
1039 mtx_init(&bqlocks[QUEUE_DIRTY], "bufq dirty lock", NULL, MTX_DEF);
1040 mtx_init(&bqlocks[QUEUE_EMPTY], "bufq empty lock", NULL, MTX_DEF);
1041 for (i = QUEUE_CLEAN; i < QUEUE_CLEAN + CLEAN_QUEUES; i++)
1042 mtx_init(&bqlocks[i], "bufq clean lock", NULL, MTX_DEF);
1043 mtx_init(&rbreqlock, "runningbufspace lock", NULL, MTX_DEF);
1044 rw_init(&nblock, "needsbuffer lock");
1045 mtx_init(&bdlock, "buffer daemon lock", NULL, MTX_DEF);
1046 mtx_init(&bdirtylock, "dirty buf lock", NULL, MTX_DEF);
1048 /* next, make a null set of free lists */
1049 for (i = 0; i < BUFFER_QUEUES; i++)
1050 TAILQ_INIT(&bufqueues[i]);
1052 unmapped_buf = (caddr_t)kva_alloc(MAXPHYS);
1054 /* finally, initialize each buffer header and stick on empty q */
1055 for (i = 0; i < nbuf; i++) {
1057 bzero(bp, sizeof *bp);
1058 bp->b_flags = B_INVAL;
1059 bp->b_rcred = NOCRED;
1060 bp->b_wcred = NOCRED;
1061 bp->b_qindex = QUEUE_EMPTY;
1063 bp->b_data = bp->b_kvabase = unmapped_buf;
1064 LIST_INIT(&bp->b_dep);
1066 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_EMPTY], bp, b_freelist);
1068 bq_len[QUEUE_EMPTY]++;
1073 * maxbufspace is the absolute maximum amount of buffer space we are
1074 * allowed to reserve in KVM and in real terms. The absolute maximum
1075 * is nominally used by metadata. hibufspace is the nominal maximum
1076 * used by most other requests. The differential is required to
1077 * ensure that metadata deadlocks don't occur.
1079 * maxbufspace is based on BKVASIZE. Allocating buffers larger then
1080 * this may result in KVM fragmentation which is not handled optimally
1081 * by the system. XXX This is less true with vmem. We could use
1084 maxbufspace = (long)nbuf * BKVASIZE;
1085 hibufspace = lmax(3 * maxbufspace / 4, maxbufspace - maxbcachebuf * 10);
1086 lobufspace = (hibufspace / 20) * 19; /* 95% */
1087 bufspacethresh = lobufspace + (hibufspace - lobufspace) / 2;
1090 * Note: The 16 MiB upper limit for hirunningspace was chosen
1091 * arbitrarily and may need further tuning. It corresponds to
1092 * 128 outstanding write IO requests (if IO size is 128 KiB),
1093 * which fits with many RAID controllers' tagged queuing limits.
1094 * The lower 1 MiB limit is the historical upper limit for
1097 hirunningspace = lmax(lmin(roundup(hibufspace / 64, maxbcachebuf),
1098 16 * 1024 * 1024), 1024 * 1024);
1099 lorunningspace = roundup((hirunningspace * 2) / 3, maxbcachebuf);
1102 * Limit the amount of malloc memory since it is wired permanently into
1103 * the kernel space. Even though this is accounted for in the buffer
1104 * allocation, we don't want the malloced region to grow uncontrolled.
1105 * The malloc scheme improves memory utilization significantly on
1106 * average (small) directories.
1108 maxbufmallocspace = hibufspace / 20;
1111 * Reduce the chance of a deadlock occurring by limiting the number
1112 * of delayed-write dirty buffers we allow to stack up.
1114 hidirtybuffers = nbuf / 4 + 20;
1115 dirtybufthresh = hidirtybuffers * 9 / 10;
1116 numdirtybuffers = 0;
1118 * To support extreme low-memory systems, make sure hidirtybuffers
1119 * cannot eat up all available buffer space. This occurs when our
1120 * minimum cannot be met. We try to size hidirtybuffers to 3/4 our
1121 * buffer space assuming BKVASIZE'd buffers.
1123 while ((long)hidirtybuffers * BKVASIZE > 3 * hibufspace / 4) {
1124 hidirtybuffers >>= 1;
1126 lodirtybuffers = hidirtybuffers / 2;
1129 * lofreebuffers should be sufficient to avoid stalling waiting on
1130 * buf headers under heavy utilization. The bufs in per-cpu caches
1131 * are counted as free but will be unavailable to threads executing
1134 * hifreebuffers is the free target for the bufspace daemon. This
1135 * should be set appropriately to limit work per-iteration.
1137 lofreebuffers = MIN((nbuf / 25) + (20 * mp_ncpus), 128 * mp_ncpus);
1138 hifreebuffers = (3 * lofreebuffers) / 2;
1139 numfreebuffers = nbuf;
1141 /* Setup the kva and free list allocators. */
1142 vmem_set_reclaim(buffer_arena, bufkva_reclaim);
1143 buf_zone = uma_zcache_create("buf free cache", sizeof(struct buf),
1144 NULL, NULL, NULL, NULL, buf_import, buf_release, NULL, 0);
1147 * Size the clean queue according to the amount of buffer space.
1148 * One queue per-256mb up to the max. More queues gives better
1149 * concurrency but less accurate LRU.
1151 clean_queues = MIN(howmany(maxbufspace, 256*1024*1024), CLEAN_QUEUES);
1157 vfs_buf_check_mapped(struct buf *bp)
1160 KASSERT(bp->b_kvabase != unmapped_buf,
1161 ("mapped buf: b_kvabase was not updated %p", bp));
1162 KASSERT(bp->b_data != unmapped_buf,
1163 ("mapped buf: b_data was not updated %p", bp));
1164 KASSERT(bp->b_data < unmapped_buf || bp->b_data >= unmapped_buf +
1165 MAXPHYS, ("b_data + b_offset unmapped %p", bp));
1169 vfs_buf_check_unmapped(struct buf *bp)
1172 KASSERT(bp->b_data == unmapped_buf,
1173 ("unmapped buf: corrupted b_data %p", bp));
1176 #define BUF_CHECK_MAPPED(bp) vfs_buf_check_mapped(bp)
1177 #define BUF_CHECK_UNMAPPED(bp) vfs_buf_check_unmapped(bp)
1179 #define BUF_CHECK_MAPPED(bp) do {} while (0)
1180 #define BUF_CHECK_UNMAPPED(bp) do {} while (0)
1184 isbufbusy(struct buf *bp)
1186 if (((bp->b_flags & B_INVAL) == 0 && BUF_ISLOCKED(bp)) ||
1187 ((bp->b_flags & (B_DELWRI | B_INVAL)) == B_DELWRI))
1193 * Shutdown the system cleanly to prepare for reboot, halt, or power off.
1196 bufshutdown(int show_busybufs)
1198 static int first_buf_printf = 1;
1200 int iter, nbusy, pbusy;
1206 * Sync filesystems for shutdown
1208 wdog_kern_pat(WD_LASTVAL);
1209 sys_sync(curthread, NULL);
1212 * With soft updates, some buffers that are
1213 * written will be remarked as dirty until other
1214 * buffers are written.
1216 for (iter = pbusy = 0; iter < 20; iter++) {
1218 for (bp = &buf[nbuf]; --bp >= buf; )
1222 if (first_buf_printf)
1223 printf("All buffers synced.");
1226 if (first_buf_printf) {
1227 printf("Syncing disks, buffers remaining... ");
1228 first_buf_printf = 0;
1230 printf("%d ", nbusy);
1235 wdog_kern_pat(WD_LASTVAL);
1236 sys_sync(curthread, NULL);
1240 * Drop Giant and spin for a while to allow
1241 * interrupt threads to run.
1244 DELAY(50000 * iter);
1248 * Drop Giant and context switch several times to
1249 * allow interrupt threads to run.
1252 for (subiter = 0; subiter < 50 * iter; subiter++) {
1253 thread_lock(curthread);
1254 mi_switch(SW_VOL, NULL);
1255 thread_unlock(curthread);
1263 * Count only busy local buffers to prevent forcing
1264 * a fsck if we're just a client of a wedged NFS server
1267 for (bp = &buf[nbuf]; --bp >= buf; ) {
1268 if (isbufbusy(bp)) {
1270 /* XXX: This is bogus. We should probably have a BO_REMOTE flag instead */
1271 if (bp->b_dev == NULL) {
1272 TAILQ_REMOVE(&mountlist,
1273 bp->b_vp->v_mount, mnt_list);
1278 if (show_busybufs > 0) {
1280 "%d: buf:%p, vnode:%p, flags:%0x, blkno:%jd, lblkno:%jd, buflock:",
1281 nbusy, bp, bp->b_vp, bp->b_flags,
1282 (intmax_t)bp->b_blkno,
1283 (intmax_t)bp->b_lblkno);
1284 BUF_LOCKPRINTINFO(bp);
1285 if (show_busybufs > 1)
1293 * Failed to sync all blocks. Indicate this and don't
1294 * unmount filesystems (thus forcing an fsck on reboot).
1296 printf("Giving up on %d buffers\n", nbusy);
1297 DELAY(5000000); /* 5 seconds */
1299 if (!first_buf_printf)
1300 printf("Final sync complete\n");
1302 * Unmount filesystems
1304 if (panicstr == NULL)
1308 DELAY(100000); /* wait for console output to finish */
1312 bpmap_qenter(struct buf *bp)
1315 BUF_CHECK_MAPPED(bp);
1318 * bp->b_data is relative to bp->b_offset, but
1319 * bp->b_offset may be offset into the first page.
1321 bp->b_data = (caddr_t)trunc_page((vm_offset_t)bp->b_data);
1322 pmap_qenter((vm_offset_t)bp->b_data, bp->b_pages, bp->b_npages);
1323 bp->b_data = (caddr_t)((vm_offset_t)bp->b_data |
1324 (vm_offset_t)(bp->b_offset & PAGE_MASK));
1330 * Insert the buffer into the appropriate free list.
1333 binsfree(struct buf *bp, int qindex)
1335 struct mtx *olock, *nlock;
1337 if (qindex != QUEUE_EMPTY) {
1338 BUF_ASSERT_XLOCKED(bp);
1342 * Stick to the same clean queue for the lifetime of the buf to
1343 * limit locking below. Otherwise pick ont sequentially.
1345 if (qindex == QUEUE_CLEAN) {
1346 if (bqisclean(bp->b_qindex))
1347 qindex = bp->b_qindex;
1349 qindex = bqcleanq();
1353 * Handle delayed bremfree() processing.
1355 nlock = bqlock(qindex);
1356 if (bp->b_flags & B_REMFREE) {
1357 olock = bqlock(bp->b_qindex);
1360 if (olock != nlock) {
1367 if (bp->b_qindex != QUEUE_NONE)
1368 panic("binsfree: free buffer onto another queue???");
1370 bp->b_qindex = qindex;
1371 if (bp->b_flags & B_AGE)
1372 TAILQ_INSERT_HEAD(&bufqueues[bp->b_qindex], bp, b_freelist);
1374 TAILQ_INSERT_TAIL(&bufqueues[bp->b_qindex], bp, b_freelist);
1376 bq_len[bp->b_qindex]++;
1384 * Free a buffer to the buf zone once it no longer has valid contents.
1387 buf_free(struct buf *bp)
1390 if (bp->b_flags & B_REMFREE)
1392 if (bp->b_vflags & BV_BKGRDINPROG)
1393 panic("losing buffer 1");
1394 if (bp->b_rcred != NOCRED) {
1395 crfree(bp->b_rcred);
1396 bp->b_rcred = NOCRED;
1398 if (bp->b_wcred != NOCRED) {
1399 crfree(bp->b_wcred);
1400 bp->b_wcred = NOCRED;
1402 if (!LIST_EMPTY(&bp->b_dep))
1406 uma_zfree(buf_zone, bp);
1407 atomic_add_int(&numfreebuffers, 1);
1414 * Import bufs into the uma cache from the buf list. The system still
1415 * expects a static array of bufs and much of the synchronization
1416 * around bufs assumes type stable storage. As a result, UMA is used
1417 * only as a per-cpu cache of bufs still maintained on a global list.
1420 buf_import(void *arg, void **store, int cnt, int flags)
1425 mtx_lock(&bqlocks[QUEUE_EMPTY]);
1426 for (i = 0; i < cnt; i++) {
1427 bp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTY]);
1433 mtx_unlock(&bqlocks[QUEUE_EMPTY]);
1441 * Release bufs from the uma cache back to the buffer queues.
1444 buf_release(void *arg, void **store, int cnt)
1448 for (i = 0; i < cnt; i++)
1449 binsfree(store[i], QUEUE_EMPTY);
1455 * Allocate an empty buffer header.
1462 bp = uma_zalloc(buf_zone, M_NOWAIT);
1464 bufspace_daemonwakeup();
1465 atomic_add_int(&numbufallocfails, 1);
1470 * Wake-up the bufspace daemon on transition.
1472 if (atomic_fetchadd_int(&numfreebuffers, -1) == lofreebuffers)
1473 bufspace_daemonwakeup();
1475 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0)
1476 panic("getnewbuf_empty: Locked buf %p on free queue.", bp);
1478 KASSERT(bp->b_vp == NULL,
1479 ("bp: %p still has vnode %p.", bp, bp->b_vp));
1480 KASSERT((bp->b_flags & (B_DELWRI | B_NOREUSE)) == 0,
1481 ("invalid buffer %p flags %#x", bp, bp->b_flags));
1482 KASSERT((bp->b_xflags & (BX_VNCLEAN|BX_VNDIRTY)) == 0,
1483 ("bp: %p still on a buffer list. xflags %X", bp, bp->b_xflags));
1484 KASSERT(bp->b_npages == 0,
1485 ("bp: %p still has %d vm pages\n", bp, bp->b_npages));
1486 KASSERT(bp->b_kvasize == 0, ("bp: %p still has kva\n", bp));
1487 KASSERT(bp->b_bufsize == 0, ("bp: %p still has bufspace\n", bp));
1494 bp->b_blkno = bp->b_lblkno = 0;
1495 bp->b_offset = NOOFFSET;
1501 bp->b_dirtyoff = bp->b_dirtyend = 0;
1502 bp->b_bufobj = NULL;
1503 bp->b_data = bp->b_kvabase = unmapped_buf;
1504 bp->b_fsprivate1 = NULL;
1505 bp->b_fsprivate2 = NULL;
1506 bp->b_fsprivate3 = NULL;
1507 LIST_INIT(&bp->b_dep);
1515 * Free a buffer from the given bufqueue. kva controls whether the
1516 * freed buf must own some kva resources. This is used for
1520 buf_qrecycle(int qindex, bool kva)
1522 struct buf *bp, *nbp;
1525 atomic_add_int(&bufdefragcnt, 1);
1527 mtx_lock(&bqlocks[qindex]);
1528 nbp = TAILQ_FIRST(&bufqueues[qindex]);
1531 * Run scan, possibly freeing data and/or kva mappings on the fly
1534 while ((bp = nbp) != NULL) {
1536 * Calculate next bp (we can only use it if we do not
1537 * release the bqlock).
1539 nbp = TAILQ_NEXT(bp, b_freelist);
1542 * If we are defragging then we need a buffer with
1543 * some kva to reclaim.
1545 if (kva && bp->b_kvasize == 0)
1548 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0)
1552 * Skip buffers with background writes in progress.
1554 if ((bp->b_vflags & BV_BKGRDINPROG) != 0) {
1559 KASSERT(bp->b_qindex == qindex,
1560 ("getnewbuf: inconsistent queue %d bp %p", qindex, bp));
1562 * NOTE: nbp is now entirely invalid. We can only restart
1563 * the scan from this point on.
1566 mtx_unlock(&bqlocks[qindex]);
1569 * Requeue the background write buffer with error and
1572 if ((bp->b_vflags & BV_BKGRDERR) != 0) {
1574 mtx_lock(&bqlocks[qindex]);
1575 nbp = TAILQ_FIRST(&bufqueues[qindex]);
1578 bp->b_flags |= B_INVAL;
1582 mtx_unlock(&bqlocks[qindex]);
1590 * Iterate through all clean queues until we find a buf to recycle or
1591 * exhaust the search.
1594 buf_recycle(bool kva)
1596 int qindex, first_qindex;
1598 qindex = first_qindex = bqcleanq();
1600 if (buf_qrecycle(qindex, kva) == 0)
1602 if (++qindex == QUEUE_CLEAN + clean_queues)
1603 qindex = QUEUE_CLEAN;
1604 } while (qindex != first_qindex);
1612 * Scan the clean queues looking for a buffer to recycle. needsbuffer
1613 * is set on failure so that the caller may optionally bufspace_wait()
1614 * in a race-free fashion.
1617 buf_scan(bool defrag)
1622 * To avoid heavy synchronization and wakeup races we set
1623 * needsbuffer and re-poll before failing. This ensures that
1624 * no frees can be missed between an unsuccessful poll and
1625 * going to sleep in a synchronized fashion.
1627 if ((error = buf_recycle(defrag)) != 0) {
1628 atomic_set_int(&needsbuffer, 1);
1629 bufspace_daemonwakeup();
1630 error = buf_recycle(defrag);
1633 atomic_add_int(&getnewbufrestarts, 1);
1640 * Mark the buffer for removal from the appropriate free list.
1644 bremfree(struct buf *bp)
1647 CTR3(KTR_BUF, "bremfree(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
1648 KASSERT((bp->b_flags & B_REMFREE) == 0,
1649 ("bremfree: buffer %p already marked for delayed removal.", bp));
1650 KASSERT(bp->b_qindex != QUEUE_NONE,
1651 ("bremfree: buffer %p not on a queue.", bp));
1652 BUF_ASSERT_XLOCKED(bp);
1654 bp->b_flags |= B_REMFREE;
1660 * Force an immediate removal from a free list. Used only in nfs when
1661 * it abuses the b_freelist pointer.
1664 bremfreef(struct buf *bp)
1668 qlock = bqlock(bp->b_qindex);
1677 * Removes a buffer from the free list, must be called with the
1678 * correct qlock held.
1681 bremfreel(struct buf *bp)
1684 CTR3(KTR_BUF, "bremfreel(%p) vp %p flags %X",
1685 bp, bp->b_vp, bp->b_flags);
1686 KASSERT(bp->b_qindex != QUEUE_NONE,
1687 ("bremfreel: buffer %p not on a queue.", bp));
1688 if (bp->b_qindex != QUEUE_EMPTY) {
1689 BUF_ASSERT_XLOCKED(bp);
1691 mtx_assert(bqlock(bp->b_qindex), MA_OWNED);
1693 TAILQ_REMOVE(&bufqueues[bp->b_qindex], bp, b_freelist);
1695 KASSERT(bq_len[bp->b_qindex] >= 1, ("queue %d underflow",
1697 bq_len[bp->b_qindex]--;
1699 bp->b_qindex = QUEUE_NONE;
1700 bp->b_flags &= ~B_REMFREE;
1706 * Free the kva allocation for a buffer.
1710 bufkva_free(struct buf *bp)
1714 if (bp->b_kvasize == 0) {
1715 KASSERT(bp->b_kvabase == unmapped_buf &&
1716 bp->b_data == unmapped_buf,
1717 ("Leaked KVA space on %p", bp));
1718 } else if (buf_mapped(bp))
1719 BUF_CHECK_MAPPED(bp);
1721 BUF_CHECK_UNMAPPED(bp);
1723 if (bp->b_kvasize == 0)
1726 vmem_free(buffer_arena, (vm_offset_t)bp->b_kvabase, bp->b_kvasize);
1727 atomic_subtract_long(&bufkvaspace, bp->b_kvasize);
1728 atomic_add_int(&buffreekvacnt, 1);
1729 bp->b_data = bp->b_kvabase = unmapped_buf;
1736 * Allocate the buffer KVA and set b_kvasize and b_kvabase.
1739 bufkva_alloc(struct buf *bp, int maxsize, int gbflags)
1744 KASSERT((gbflags & GB_UNMAPPED) == 0 || (gbflags & GB_KVAALLOC) != 0,
1745 ("Invalid gbflags 0x%x in %s", gbflags, __func__));
1750 error = vmem_alloc(buffer_arena, maxsize, M_BESTFIT | M_NOWAIT, &addr);
1753 * Buffer map is too fragmented. Request the caller
1754 * to defragment the map.
1758 bp->b_kvabase = (caddr_t)addr;
1759 bp->b_kvasize = maxsize;
1760 atomic_add_long(&bufkvaspace, bp->b_kvasize);
1761 if ((gbflags & GB_UNMAPPED) != 0) {
1762 bp->b_data = unmapped_buf;
1763 BUF_CHECK_UNMAPPED(bp);
1765 bp->b_data = bp->b_kvabase;
1766 BUF_CHECK_MAPPED(bp);
1774 * Reclaim buffer kva by freeing buffers holding kva. This is a vmem
1775 * callback that fires to avoid returning failure.
1778 bufkva_reclaim(vmem_t *vmem, int flags)
1782 for (i = 0; i < 5; i++)
1783 if (buf_scan(true) != 0)
1789 * Attempt to initiate asynchronous I/O on read-ahead blocks. We must
1790 * clear BIO_ERROR and B_INVAL prior to initiating I/O . If B_CACHE is set,
1791 * the buffer is valid and we do not have to do anything.
1794 breada(struct vnode * vp, daddr_t * rablkno, int * rabsize, int cnt,
1795 struct ucred * cred, int flags, void (*ckhashfunc)(struct buf *))
1800 for (i = 0; i < cnt; i++, rablkno++, rabsize++) {
1801 if (inmem(vp, *rablkno))
1803 rabp = getblk(vp, *rablkno, *rabsize, 0, 0, 0);
1804 if ((rabp->b_flags & B_CACHE) != 0) {
1808 if (!TD_IS_IDLETHREAD(curthread)) {
1812 racct_add_buf(curproc, rabp, 0);
1813 PROC_UNLOCK(curproc);
1816 curthread->td_ru.ru_inblock++;
1818 rabp->b_flags |= B_ASYNC;
1819 rabp->b_flags &= ~B_INVAL;
1820 if ((flags & GB_CKHASH) != 0) {
1821 rabp->b_flags |= B_CKHASH;
1822 rabp->b_ckhashcalc = ckhashfunc;
1824 rabp->b_ioflags &= ~BIO_ERROR;
1825 rabp->b_iocmd = BIO_READ;
1826 if (rabp->b_rcred == NOCRED && cred != NOCRED)
1827 rabp->b_rcred = crhold(cred);
1828 vfs_busy_pages(rabp, 0);
1830 rabp->b_iooffset = dbtob(rabp->b_blkno);
1836 * Entry point for bread() and breadn() via #defines in sys/buf.h.
1838 * Get a buffer with the specified data. Look in the cache first. We
1839 * must clear BIO_ERROR and B_INVAL prior to initiating I/O. If B_CACHE
1840 * is set, the buffer is valid and we do not have to do anything, see
1841 * getblk(). Also starts asynchronous I/O on read-ahead blocks.
1843 * Always return a NULL buffer pointer (in bpp) when returning an error.
1846 breadn_flags(struct vnode *vp, daddr_t blkno, int size, daddr_t *rablkno,
1847 int *rabsize, int cnt, struct ucred *cred, int flags,
1848 void (*ckhashfunc)(struct buf *), struct buf **bpp)
1853 CTR3(KTR_BUF, "breadn(%p, %jd, %d)", vp, blkno, size);
1855 * Can only return NULL if GB_LOCK_NOWAIT flag is specified.
1857 *bpp = bp = getblk(vp, blkno, size, 0, 0, flags);
1862 * If not found in cache, do some I/O
1865 if ((bp->b_flags & B_CACHE) == 0) {
1866 if (!TD_IS_IDLETHREAD(curthread)) {
1870 racct_add_buf(curproc, bp, 0);
1871 PROC_UNLOCK(curproc);
1874 curthread->td_ru.ru_inblock++;
1876 bp->b_iocmd = BIO_READ;
1877 bp->b_flags &= ~B_INVAL;
1878 if ((flags & GB_CKHASH) != 0) {
1879 bp->b_flags |= B_CKHASH;
1880 bp->b_ckhashcalc = ckhashfunc;
1882 bp->b_ioflags &= ~BIO_ERROR;
1883 if (bp->b_rcred == NOCRED && cred != NOCRED)
1884 bp->b_rcred = crhold(cred);
1885 vfs_busy_pages(bp, 0);
1886 bp->b_iooffset = dbtob(bp->b_blkno);
1892 * Attempt to initiate asynchronous I/O on read-ahead blocks.
1894 breada(vp, rablkno, rabsize, cnt, cred, flags, ckhashfunc);
1908 * Write, release buffer on completion. (Done by iodone
1909 * if async). Do not bother writing anything if the buffer
1912 * Note that we set B_CACHE here, indicating that buffer is
1913 * fully valid and thus cacheable. This is true even of NFS
1914 * now so we set it generally. This could be set either here
1915 * or in biodone() since the I/O is synchronous. We put it
1919 bufwrite(struct buf *bp)
1926 CTR3(KTR_BUF, "bufwrite(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
1927 if ((bp->b_bufobj->bo_flag & BO_DEAD) != 0) {
1928 bp->b_flags |= B_INVAL | B_RELBUF;
1929 bp->b_flags &= ~B_CACHE;
1933 if (bp->b_flags & B_INVAL) {
1938 if (bp->b_flags & B_BARRIER)
1941 oldflags = bp->b_flags;
1943 BUF_ASSERT_HELD(bp);
1945 KASSERT(!(bp->b_vflags & BV_BKGRDINPROG),
1946 ("FFS background buffer should not get here %p", bp));
1950 vp_md = vp->v_vflag & VV_MD;
1955 * Mark the buffer clean. Increment the bufobj write count
1956 * before bundirty() call, to prevent other thread from seeing
1957 * empty dirty list and zero counter for writes in progress,
1958 * falsely indicating that the bufobj is clean.
1960 bufobj_wref(bp->b_bufobj);
1963 bp->b_flags &= ~B_DONE;
1964 bp->b_ioflags &= ~BIO_ERROR;
1965 bp->b_flags |= B_CACHE;
1966 bp->b_iocmd = BIO_WRITE;
1968 vfs_busy_pages(bp, 1);
1971 * Normal bwrites pipeline writes
1973 bp->b_runningbufspace = bp->b_bufsize;
1974 space = atomic_fetchadd_long(&runningbufspace, bp->b_runningbufspace);
1976 if (!TD_IS_IDLETHREAD(curthread)) {
1980 racct_add_buf(curproc, bp, 1);
1981 PROC_UNLOCK(curproc);
1984 curthread->td_ru.ru_oublock++;
1986 if (oldflags & B_ASYNC)
1988 bp->b_iooffset = dbtob(bp->b_blkno);
1989 buf_track(bp, __func__);
1992 if ((oldflags & B_ASYNC) == 0) {
1993 int rtval = bufwait(bp);
1996 } else if (space > hirunningspace) {
1998 * don't allow the async write to saturate the I/O
1999 * system. We will not deadlock here because
2000 * we are blocking waiting for I/O that is already in-progress
2001 * to complete. We do not block here if it is the update
2002 * or syncer daemon trying to clean up as that can lead
2005 if ((curthread->td_pflags & TDP_NORUNNINGBUF) == 0 && !vp_md)
2006 waitrunningbufspace();
2013 bufbdflush(struct bufobj *bo, struct buf *bp)
2017 if (bo->bo_dirty.bv_cnt > dirtybufthresh + 10) {
2018 (void) VOP_FSYNC(bp->b_vp, MNT_NOWAIT, curthread);
2020 } else if (bo->bo_dirty.bv_cnt > dirtybufthresh) {
2023 * Try to find a buffer to flush.
2025 TAILQ_FOREACH(nbp, &bo->bo_dirty.bv_hd, b_bobufs) {
2026 if ((nbp->b_vflags & BV_BKGRDINPROG) ||
2028 LK_EXCLUSIVE | LK_NOWAIT, NULL))
2031 panic("bdwrite: found ourselves");
2033 /* Don't countdeps with the bo lock held. */
2034 if (buf_countdeps(nbp, 0)) {
2039 if (nbp->b_flags & B_CLUSTEROK) {
2040 vfs_bio_awrite(nbp);
2045 dirtybufferflushes++;
2054 * Delayed write. (Buffer is marked dirty). Do not bother writing
2055 * anything if the buffer is marked invalid.
2057 * Note that since the buffer must be completely valid, we can safely
2058 * set B_CACHE. In fact, we have to set B_CACHE here rather then in
2059 * biodone() in order to prevent getblk from writing the buffer
2060 * out synchronously.
2063 bdwrite(struct buf *bp)
2065 struct thread *td = curthread;
2069 CTR3(KTR_BUF, "bdwrite(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
2070 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp));
2071 KASSERT((bp->b_flags & B_BARRIER) == 0,
2072 ("Barrier request in delayed write %p", bp));
2073 BUF_ASSERT_HELD(bp);
2075 if (bp->b_flags & B_INVAL) {
2081 * If we have too many dirty buffers, don't create any more.
2082 * If we are wildly over our limit, then force a complete
2083 * cleanup. Otherwise, just keep the situation from getting
2084 * out of control. Note that we have to avoid a recursive
2085 * disaster and not try to clean up after our own cleanup!
2089 if ((td->td_pflags & (TDP_COWINPROGRESS|TDP_INBDFLUSH)) == 0) {
2090 td->td_pflags |= TDP_INBDFLUSH;
2092 td->td_pflags &= ~TDP_INBDFLUSH;
2098 * Set B_CACHE, indicating that the buffer is fully valid. This is
2099 * true even of NFS now.
2101 bp->b_flags |= B_CACHE;
2104 * This bmap keeps the system from needing to do the bmap later,
2105 * perhaps when the system is attempting to do a sync. Since it
2106 * is likely that the indirect block -- or whatever other datastructure
2107 * that the filesystem needs is still in memory now, it is a good
2108 * thing to do this. Note also, that if the pageout daemon is
2109 * requesting a sync -- there might not be enough memory to do
2110 * the bmap then... So, this is important to do.
2112 if (vp->v_type != VCHR && bp->b_lblkno == bp->b_blkno) {
2113 VOP_BMAP(vp, bp->b_lblkno, NULL, &bp->b_blkno, NULL, NULL);
2116 buf_track(bp, __func__);
2119 * Set the *dirty* buffer range based upon the VM system dirty
2122 * Mark the buffer pages as clean. We need to do this here to
2123 * satisfy the vnode_pager and the pageout daemon, so that it
2124 * thinks that the pages have been "cleaned". Note that since
2125 * the pages are in a delayed write buffer -- the VFS layer
2126 * "will" see that the pages get written out on the next sync,
2127 * or perhaps the cluster will be completed.
2129 vfs_clean_pages_dirty_buf(bp);
2133 * note: we cannot initiate I/O from a bdwrite even if we wanted to,
2134 * due to the softdep code.
2141 * Turn buffer into delayed write request. We must clear BIO_READ and
2142 * B_RELBUF, and we must set B_DELWRI. We reassign the buffer to
2143 * itself to properly update it in the dirty/clean lists. We mark it
2144 * B_DONE to ensure that any asynchronization of the buffer properly
2145 * clears B_DONE ( else a panic will occur later ).
2147 * bdirty() is kinda like bdwrite() - we have to clear B_INVAL which
2148 * might have been set pre-getblk(). Unlike bwrite/bdwrite, bdirty()
2149 * should only be called if the buffer is known-good.
2151 * Since the buffer is not on a queue, we do not update the numfreebuffers
2154 * The buffer must be on QUEUE_NONE.
2157 bdirty(struct buf *bp)
2160 CTR3(KTR_BUF, "bdirty(%p) vp %p flags %X",
2161 bp, bp->b_vp, bp->b_flags);
2162 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp));
2163 KASSERT(bp->b_flags & B_REMFREE || bp->b_qindex == QUEUE_NONE,
2164 ("bdirty: buffer %p still on queue %d", bp, bp->b_qindex));
2165 BUF_ASSERT_HELD(bp);
2166 bp->b_flags &= ~(B_RELBUF);
2167 bp->b_iocmd = BIO_WRITE;
2169 if ((bp->b_flags & B_DELWRI) == 0) {
2170 bp->b_flags |= /* XXX B_DONE | */ B_DELWRI;
2179 * Clear B_DELWRI for buffer.
2181 * Since the buffer is not on a queue, we do not update the numfreebuffers
2184 * The buffer must be on QUEUE_NONE.
2188 bundirty(struct buf *bp)
2191 CTR3(KTR_BUF, "bundirty(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
2192 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp));
2193 KASSERT(bp->b_flags & B_REMFREE || bp->b_qindex == QUEUE_NONE,
2194 ("bundirty: buffer %p still on queue %d", bp, bp->b_qindex));
2195 BUF_ASSERT_HELD(bp);
2197 if (bp->b_flags & B_DELWRI) {
2198 bp->b_flags &= ~B_DELWRI;
2203 * Since it is now being written, we can clear its deferred write flag.
2205 bp->b_flags &= ~B_DEFERRED;
2211 * Asynchronous write. Start output on a buffer, but do not wait for
2212 * it to complete. The buffer is released when the output completes.
2214 * bwrite() ( or the VOP routine anyway ) is responsible for handling
2215 * B_INVAL buffers. Not us.
2218 bawrite(struct buf *bp)
2221 bp->b_flags |= B_ASYNC;
2228 * Asynchronous barrier write. Start output on a buffer, but do not
2229 * wait for it to complete. Place a write barrier after this write so
2230 * that this buffer and all buffers written before it are committed to
2231 * the disk before any buffers written after this write are committed
2232 * to the disk. The buffer is released when the output completes.
2235 babarrierwrite(struct buf *bp)
2238 bp->b_flags |= B_ASYNC | B_BARRIER;
2245 * Synchronous barrier write. Start output on a buffer and wait for
2246 * it to complete. Place a write barrier after this write so that
2247 * this buffer and all buffers written before it are committed to
2248 * the disk before any buffers written after this write are committed
2249 * to the disk. The buffer is released when the output completes.
2252 bbarrierwrite(struct buf *bp)
2255 bp->b_flags |= B_BARRIER;
2256 return (bwrite(bp));
2262 * Called prior to the locking of any vnodes when we are expecting to
2263 * write. We do not want to starve the buffer cache with too many
2264 * dirty buffers so we block here. By blocking prior to the locking
2265 * of any vnodes we attempt to avoid the situation where a locked vnode
2266 * prevents the various system daemons from flushing related buffers.
2272 if (numdirtybuffers >= hidirtybuffers) {
2273 mtx_lock(&bdirtylock);
2274 while (numdirtybuffers >= hidirtybuffers) {
2276 msleep(&bdirtywait, &bdirtylock, (PRIBIO + 4),
2279 mtx_unlock(&bdirtylock);
2284 * Return true if we have too many dirty buffers.
2287 buf_dirty_count_severe(void)
2290 return(numdirtybuffers >= hidirtybuffers);
2296 * Release a busy buffer and, if requested, free its resources. The
2297 * buffer will be stashed in the appropriate bufqueue[] allowing it
2298 * to be accessed later as a cache entity or reused for other purposes.
2301 brelse(struct buf *bp)
2306 * Many functions erroneously call brelse with a NULL bp under rare
2307 * error conditions. Simply return when called with a NULL bp.
2311 CTR3(KTR_BUF, "brelse(%p) vp %p flags %X",
2312 bp, bp->b_vp, bp->b_flags);
2313 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)),
2314 ("brelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp));
2315 KASSERT((bp->b_flags & B_VMIO) != 0 || (bp->b_flags & B_NOREUSE) == 0,
2316 ("brelse: non-VMIO buffer marked NOREUSE"));
2318 if (BUF_LOCKRECURSED(bp)) {
2320 * Do not process, in particular, do not handle the
2321 * B_INVAL/B_RELBUF and do not release to free list.
2327 if (bp->b_flags & B_MANAGED) {
2332 if ((bp->b_vflags & (BV_BKGRDINPROG | BV_BKGRDERR)) == BV_BKGRDERR) {
2333 BO_LOCK(bp->b_bufobj);
2334 bp->b_vflags &= ~BV_BKGRDERR;
2335 BO_UNLOCK(bp->b_bufobj);
2338 if (bp->b_iocmd == BIO_WRITE && (bp->b_ioflags & BIO_ERROR) &&
2339 (bp->b_error != ENXIO || !LIST_EMPTY(&bp->b_dep)) &&
2340 !(bp->b_flags & B_INVAL)) {
2342 * Failed write, redirty. All errors except ENXIO (which
2343 * means the device is gone) are expected to be potentially
2344 * transient - underlying media might work if tried again
2345 * after EIO, and memory might be available after an ENOMEM.
2347 * Do this also for buffers that failed with ENXIO, but have
2348 * non-empty dependencies - the soft updates code might need
2349 * to access the buffer to untangle them.
2351 * Must clear BIO_ERROR to prevent pages from being scrapped.
2353 bp->b_ioflags &= ~BIO_ERROR;
2355 } else if ((bp->b_flags & (B_NOCACHE | B_INVAL)) ||
2356 (bp->b_ioflags & BIO_ERROR) || (bp->b_bufsize <= 0)) {
2358 * Either a failed read I/O, or we were asked to free or not
2359 * cache the buffer, or we failed to write to a device that's
2360 * no longer present.
2362 bp->b_flags |= B_INVAL;
2363 if (!LIST_EMPTY(&bp->b_dep))
2365 if (bp->b_flags & B_DELWRI)
2367 bp->b_flags &= ~(B_DELWRI | B_CACHE);
2368 if ((bp->b_flags & B_VMIO) == 0) {
2376 * We must clear B_RELBUF if B_DELWRI is set. If vfs_vmio_truncate()
2377 * is called with B_DELWRI set, the underlying pages may wind up
2378 * getting freed causing a previous write (bdwrite()) to get 'lost'
2379 * because pages associated with a B_DELWRI bp are marked clean.
2381 * We still allow the B_INVAL case to call vfs_vmio_truncate(), even
2382 * if B_DELWRI is set.
2384 if (bp->b_flags & B_DELWRI)
2385 bp->b_flags &= ~B_RELBUF;
2388 * VMIO buffer rundown. It is not very necessary to keep a VMIO buffer
2389 * constituted, not even NFS buffers now. Two flags effect this. If
2390 * B_INVAL, the struct buf is invalidated but the VM object is kept
2391 * around ( i.e. so it is trivial to reconstitute the buffer later ).
2393 * If BIO_ERROR or B_NOCACHE is set, pages in the VM object will be
2394 * invalidated. BIO_ERROR cannot be set for a failed write unless the
2395 * buffer is also B_INVAL because it hits the re-dirtying code above.
2397 * Normally we can do this whether a buffer is B_DELWRI or not. If
2398 * the buffer is an NFS buffer, it is tracking piecemeal writes or
2399 * the commit state and we cannot afford to lose the buffer. If the
2400 * buffer has a background write in progress, we need to keep it
2401 * around to prevent it from being reconstituted and starting a second
2404 if ((bp->b_flags & B_VMIO) && (bp->b_flags & B_NOCACHE ||
2405 (bp->b_ioflags & BIO_ERROR && bp->b_iocmd == BIO_READ)) &&
2406 !(bp->b_vp->v_mount != NULL &&
2407 (bp->b_vp->v_mount->mnt_vfc->vfc_flags & VFCF_NETWORK) != 0 &&
2408 !vn_isdisk(bp->b_vp, NULL) && (bp->b_flags & B_DELWRI))) {
2409 vfs_vmio_invalidate(bp);
2413 if ((bp->b_flags & (B_INVAL | B_RELBUF)) != 0 ||
2414 (bp->b_flags & (B_DELWRI | B_NOREUSE)) == B_NOREUSE) {
2416 bp->b_flags &= ~B_NOREUSE;
2417 if (bp->b_vp != NULL)
2422 * If the buffer has junk contents signal it and eventually
2423 * clean up B_DELWRI and diassociate the vnode so that gbincore()
2426 if (bp->b_bufsize == 0 || (bp->b_ioflags & BIO_ERROR) != 0 ||
2427 (bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF)) != 0)
2428 bp->b_flags |= B_INVAL;
2429 if (bp->b_flags & B_INVAL) {
2430 if (bp->b_flags & B_DELWRI)
2436 buf_track(bp, __func__);
2438 /* buffers with no memory */
2439 if (bp->b_bufsize == 0) {
2443 /* buffers with junk contents */
2444 if (bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF) ||
2445 (bp->b_ioflags & BIO_ERROR)) {
2446 bp->b_xflags &= ~(BX_BKGRDWRITE | BX_ALTDATA);
2447 if (bp->b_vflags & BV_BKGRDINPROG)
2448 panic("losing buffer 2");
2449 qindex = QUEUE_CLEAN;
2450 bp->b_flags |= B_AGE;
2451 /* remaining buffers */
2452 } else if (bp->b_flags & B_DELWRI)
2453 qindex = QUEUE_DIRTY;
2455 qindex = QUEUE_CLEAN;
2457 binsfree(bp, qindex);
2459 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF | B_DIRECT);
2460 if ((bp->b_flags & B_DELWRI) == 0 && (bp->b_xflags & BX_VNDIRTY))
2461 panic("brelse: not dirty");
2464 if (qindex == QUEUE_CLEAN)
2469 * Release a buffer back to the appropriate queue but do not try to free
2470 * it. The buffer is expected to be used again soon.
2472 * bqrelse() is used by bdwrite() to requeue a delayed write, and used by
2473 * biodone() to requeue an async I/O on completion. It is also used when
2474 * known good buffers need to be requeued but we think we may need the data
2477 * XXX we should be able to leave the B_RELBUF hint set on completion.
2480 bqrelse(struct buf *bp)
2484 CTR3(KTR_BUF, "bqrelse(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
2485 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)),
2486 ("bqrelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp));
2488 qindex = QUEUE_NONE;
2489 if (BUF_LOCKRECURSED(bp)) {
2490 /* do not release to free list */
2494 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF);
2496 if (bp->b_flags & B_MANAGED) {
2497 if (bp->b_flags & B_REMFREE)
2502 /* buffers with stale but valid contents */
2503 if ((bp->b_flags & B_DELWRI) != 0 || (bp->b_vflags & (BV_BKGRDINPROG |
2504 BV_BKGRDERR)) == BV_BKGRDERR) {
2505 BO_LOCK(bp->b_bufobj);
2506 bp->b_vflags &= ~BV_BKGRDERR;
2507 BO_UNLOCK(bp->b_bufobj);
2508 qindex = QUEUE_DIRTY;
2510 if ((bp->b_flags & B_DELWRI) == 0 &&
2511 (bp->b_xflags & BX_VNDIRTY))
2512 panic("bqrelse: not dirty");
2513 if ((bp->b_flags & B_NOREUSE) != 0) {
2517 qindex = QUEUE_CLEAN;
2519 binsfree(bp, qindex);
2522 buf_track(bp, __func__);
2525 if (qindex == QUEUE_CLEAN)
2530 * Complete I/O to a VMIO backed page. Validate the pages as appropriate,
2531 * restore bogus pages.
2534 vfs_vmio_iodone(struct buf *bp)
2540 int i, iosize, resid;
2543 obj = bp->b_bufobj->bo_object;
2544 KASSERT(obj->paging_in_progress >= bp->b_npages,
2545 ("vfs_vmio_iodone: paging in progress(%d) < b_npages(%d)",
2546 obj->paging_in_progress, bp->b_npages));
2549 KASSERT(vp->v_holdcnt > 0,
2550 ("vfs_vmio_iodone: vnode %p has zero hold count", vp));
2551 KASSERT(vp->v_object != NULL,
2552 ("vfs_vmio_iodone: vnode %p has no vm_object", vp));
2554 foff = bp->b_offset;
2555 KASSERT(bp->b_offset != NOOFFSET,
2556 ("vfs_vmio_iodone: bp %p has no buffer offset", bp));
2559 iosize = bp->b_bcount - bp->b_resid;
2560 VM_OBJECT_WLOCK(obj);
2561 for (i = 0; i < bp->b_npages; i++) {
2562 resid = ((foff + PAGE_SIZE) & ~(off_t)PAGE_MASK) - foff;
2567 * cleanup bogus pages, restoring the originals
2570 if (m == bogus_page) {
2572 m = vm_page_lookup(obj, OFF_TO_IDX(foff));
2574 panic("biodone: page disappeared!");
2576 } else if ((bp->b_iocmd == BIO_READ) && resid > 0) {
2578 * In the write case, the valid and clean bits are
2579 * already changed correctly ( see bdwrite() ), so we
2580 * only need to do this here in the read case.
2582 KASSERT((m->dirty & vm_page_bits(foff & PAGE_MASK,
2583 resid)) == 0, ("vfs_vmio_iodone: page %p "
2584 "has unexpected dirty bits", m));
2585 vfs_page_set_valid(bp, foff, m);
2587 KASSERT(OFF_TO_IDX(foff) == m->pindex,
2588 ("vfs_vmio_iodone: foff(%jd)/pindex(%ju) mismatch",
2589 (intmax_t)foff, (uintmax_t)m->pindex));
2592 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK;
2595 vm_object_pip_wakeupn(obj, bp->b_npages);
2596 VM_OBJECT_WUNLOCK(obj);
2597 if (bogus && buf_mapped(bp)) {
2598 BUF_CHECK_MAPPED(bp);
2599 pmap_qenter(trunc_page((vm_offset_t)bp->b_data),
2600 bp->b_pages, bp->b_npages);
2605 * Unwire a page held by a buf and place it on the appropriate vm queue.
2608 vfs_vmio_unwire(struct buf *bp, vm_page_t m)
2613 if (vm_page_unwire(m, PQ_NONE)) {
2615 * Determine if the page should be freed before adding
2616 * it to the inactive queue.
2618 if (m->valid == 0) {
2619 freed = !vm_page_busied(m);
2622 } else if ((bp->b_flags & B_DIRECT) != 0)
2623 freed = vm_page_try_to_free(m);
2628 * If the page is unlikely to be reused, let the
2629 * VM know. Otherwise, maintain LRU page
2630 * ordering and put the page at the tail of the
2633 if ((bp->b_flags & B_NOREUSE) != 0)
2634 vm_page_deactivate_noreuse(m);
2636 vm_page_deactivate(m);
2643 * Perform page invalidation when a buffer is released. The fully invalid
2644 * pages will be reclaimed later in vfs_vmio_truncate().
2647 vfs_vmio_invalidate(struct buf *bp)
2651 int i, resid, poffset, presid;
2653 if (buf_mapped(bp)) {
2654 BUF_CHECK_MAPPED(bp);
2655 pmap_qremove(trunc_page((vm_offset_t)bp->b_data), bp->b_npages);
2657 BUF_CHECK_UNMAPPED(bp);
2659 * Get the base offset and length of the buffer. Note that
2660 * in the VMIO case if the buffer block size is not
2661 * page-aligned then b_data pointer may not be page-aligned.
2662 * But our b_pages[] array *IS* page aligned.
2664 * block sizes less then DEV_BSIZE (usually 512) are not
2665 * supported due to the page granularity bits (m->valid,
2666 * m->dirty, etc...).
2668 * See man buf(9) for more information
2670 obj = bp->b_bufobj->bo_object;
2671 resid = bp->b_bufsize;
2672 poffset = bp->b_offset & PAGE_MASK;
2673 VM_OBJECT_WLOCK(obj);
2674 for (i = 0; i < bp->b_npages; i++) {
2676 if (m == bogus_page)
2677 panic("vfs_vmio_invalidate: Unexpected bogus page.");
2678 bp->b_pages[i] = NULL;
2680 presid = resid > (PAGE_SIZE - poffset) ?
2681 (PAGE_SIZE - poffset) : resid;
2682 KASSERT(presid >= 0, ("brelse: extra page"));
2683 while (vm_page_xbusied(m)) {
2685 VM_OBJECT_WUNLOCK(obj);
2686 vm_page_busy_sleep(m, "mbncsh", true);
2687 VM_OBJECT_WLOCK(obj);
2689 if (pmap_page_wired_mappings(m) == 0)
2690 vm_page_set_invalid(m, poffset, presid);
2691 vfs_vmio_unwire(bp, m);
2695 VM_OBJECT_WUNLOCK(obj);
2700 * Page-granular truncation of an existing VMIO buffer.
2703 vfs_vmio_truncate(struct buf *bp, int desiredpages)
2709 if (bp->b_npages == desiredpages)
2712 if (buf_mapped(bp)) {
2713 BUF_CHECK_MAPPED(bp);
2714 pmap_qremove((vm_offset_t)trunc_page((vm_offset_t)bp->b_data) +
2715 (desiredpages << PAGE_SHIFT), bp->b_npages - desiredpages);
2717 BUF_CHECK_UNMAPPED(bp);
2718 obj = bp->b_bufobj->bo_object;
2720 VM_OBJECT_WLOCK(obj);
2721 for (i = desiredpages; i < bp->b_npages; i++) {
2723 KASSERT(m != bogus_page, ("allocbuf: bogus page found"));
2724 bp->b_pages[i] = NULL;
2725 vfs_vmio_unwire(bp, m);
2728 VM_OBJECT_WUNLOCK(obj);
2729 bp->b_npages = desiredpages;
2733 * Byte granular extension of VMIO buffers.
2736 vfs_vmio_extend(struct buf *bp, int desiredpages, int size)
2739 * We are growing the buffer, possibly in a
2740 * byte-granular fashion.
2748 * Step 1, bring in the VM pages from the object, allocating
2749 * them if necessary. We must clear B_CACHE if these pages
2750 * are not valid for the range covered by the buffer.
2752 obj = bp->b_bufobj->bo_object;
2753 VM_OBJECT_WLOCK(obj);
2754 if (bp->b_npages < desiredpages) {
2756 * We must allocate system pages since blocking
2757 * here could interfere with paging I/O, no
2758 * matter which process we are.
2760 * Only exclusive busy can be tested here.
2761 * Blocking on shared busy might lead to
2762 * deadlocks once allocbuf() is called after
2763 * pages are vfs_busy_pages().
2765 (void)vm_page_grab_pages(obj,
2766 OFF_TO_IDX(bp->b_offset) + bp->b_npages,
2767 VM_ALLOC_SYSTEM | VM_ALLOC_IGN_SBUSY |
2768 VM_ALLOC_NOBUSY | VM_ALLOC_WIRED,
2769 &bp->b_pages[bp->b_npages], desiredpages - bp->b_npages);
2770 bp->b_npages = desiredpages;
2774 * Step 2. We've loaded the pages into the buffer,
2775 * we have to figure out if we can still have B_CACHE
2776 * set. Note that B_CACHE is set according to the
2777 * byte-granular range ( bcount and size ), not the
2778 * aligned range ( newbsize ).
2780 * The VM test is against m->valid, which is DEV_BSIZE
2781 * aligned. Needless to say, the validity of the data
2782 * needs to also be DEV_BSIZE aligned. Note that this
2783 * fails with NFS if the server or some other client
2784 * extends the file's EOF. If our buffer is resized,
2785 * B_CACHE may remain set! XXX
2787 toff = bp->b_bcount;
2788 tinc = PAGE_SIZE - ((bp->b_offset + toff) & PAGE_MASK);
2789 while ((bp->b_flags & B_CACHE) && toff < size) {
2792 if (tinc > (size - toff))
2794 pi = ((bp->b_offset & PAGE_MASK) + toff) >> PAGE_SHIFT;
2795 m = bp->b_pages[pi];
2796 vfs_buf_test_cache(bp, bp->b_offset, toff, tinc, m);
2800 VM_OBJECT_WUNLOCK(obj);
2803 * Step 3, fixup the KVA pmap.
2808 BUF_CHECK_UNMAPPED(bp);
2812 * Check to see if a block at a particular lbn is available for a clustered
2816 vfs_bio_clcheck(struct vnode *vp, int size, daddr_t lblkno, daddr_t blkno)
2823 /* If the buf isn't in core skip it */
2824 if ((bpa = gbincore(&vp->v_bufobj, lblkno)) == NULL)
2827 /* If the buf is busy we don't want to wait for it */
2828 if (BUF_LOCK(bpa, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0)
2831 /* Only cluster with valid clusterable delayed write buffers */
2832 if ((bpa->b_flags & (B_DELWRI | B_CLUSTEROK | B_INVAL)) !=
2833 (B_DELWRI | B_CLUSTEROK))
2836 if (bpa->b_bufsize != size)
2840 * Check to see if it is in the expected place on disk and that the
2841 * block has been mapped.
2843 if ((bpa->b_blkno != bpa->b_lblkno) && (bpa->b_blkno == blkno))
2853 * Implement clustered async writes for clearing out B_DELWRI buffers.
2854 * This is much better then the old way of writing only one buffer at
2855 * a time. Note that we may not be presented with the buffers in the
2856 * correct order, so we search for the cluster in both directions.
2859 vfs_bio_awrite(struct buf *bp)
2864 daddr_t lblkno = bp->b_lblkno;
2865 struct vnode *vp = bp->b_vp;
2873 gbflags = (bp->b_data == unmapped_buf) ? GB_UNMAPPED : 0;
2875 * right now we support clustered writing only to regular files. If
2876 * we find a clusterable block we could be in the middle of a cluster
2877 * rather then at the beginning.
2879 if ((vp->v_type == VREG) &&
2880 (vp->v_mount != 0) && /* Only on nodes that have the size info */
2881 (bp->b_flags & (B_CLUSTEROK | B_INVAL)) == B_CLUSTEROK) {
2883 size = vp->v_mount->mnt_stat.f_iosize;
2884 maxcl = MAXPHYS / size;
2887 for (i = 1; i < maxcl; i++)
2888 if (vfs_bio_clcheck(vp, size, lblkno + i,
2889 bp->b_blkno + ((i * size) >> DEV_BSHIFT)) == 0)
2892 for (j = 1; i + j <= maxcl && j <= lblkno; j++)
2893 if (vfs_bio_clcheck(vp, size, lblkno - j,
2894 bp->b_blkno - ((j * size) >> DEV_BSHIFT)) == 0)
2900 * this is a possible cluster write
2904 nwritten = cluster_wbuild(vp, size, lblkno - j, ncl,
2910 bp->b_flags |= B_ASYNC;
2912 * default (old) behavior, writing out only one block
2914 * XXX returns b_bufsize instead of b_bcount for nwritten?
2916 nwritten = bp->b_bufsize;
2925 * Allocate KVA for an empty buf header according to gbflags.
2928 getnewbuf_kva(struct buf *bp, int gbflags, int maxsize)
2931 if ((gbflags & (GB_UNMAPPED | GB_KVAALLOC)) != GB_UNMAPPED) {
2933 * In order to keep fragmentation sane we only allocate kva
2934 * in BKVASIZE chunks. XXX with vmem we can do page size.
2936 maxsize = (maxsize + BKVAMASK) & ~BKVAMASK;
2938 if (maxsize != bp->b_kvasize &&
2939 bufkva_alloc(bp, maxsize, gbflags))
2948 * Find and initialize a new buffer header, freeing up existing buffers
2949 * in the bufqueues as necessary. The new buffer is returned locked.
2952 * We have insufficient buffer headers
2953 * We have insufficient buffer space
2954 * buffer_arena is too fragmented ( space reservation fails )
2955 * If we have to flush dirty buffers ( but we try to avoid this )
2957 * The caller is responsible for releasing the reserved bufspace after
2958 * allocbuf() is called.
2961 getnewbuf(struct vnode *vp, int slpflag, int slptimeo, int maxsize, int gbflags)
2964 bool metadata, reserved;
2967 KASSERT((gbflags & (GB_UNMAPPED | GB_KVAALLOC)) != GB_KVAALLOC,
2968 ("GB_KVAALLOC only makes sense with GB_UNMAPPED"));
2969 if (!unmapped_buf_allowed)
2970 gbflags &= ~(GB_UNMAPPED | GB_KVAALLOC);
2972 if (vp == NULL || (vp->v_vflag & (VV_MD | VV_SYSTEM)) != 0 ||
2977 atomic_add_int(&getnewbufcalls, 1);
2980 if (reserved == false &&
2981 bufspace_reserve(maxsize, metadata) != 0)
2984 if ((bp = buf_alloc()) == NULL)
2986 if (getnewbuf_kva(bp, gbflags, maxsize) == 0)
2989 } while(buf_scan(false) == 0);
2992 atomic_subtract_long(&bufspace, maxsize);
2994 bp->b_flags |= B_INVAL;
2997 bufspace_wait(vp, gbflags, slpflag, slptimeo);
3005 * buffer flushing daemon. Buffers are normally flushed by the
3006 * update daemon but if it cannot keep up this process starts to
3007 * take the load in an attempt to prevent getnewbuf() from blocking.
3009 static struct kproc_desc buf_kp = {
3014 SYSINIT(bufdaemon, SI_SUB_KTHREAD_BUF, SI_ORDER_FIRST, kproc_start, &buf_kp);
3017 buf_flush(struct vnode *vp, int target)
3021 flushed = flushbufqueues(vp, target, 0);
3024 * Could not find any buffers without rollback
3025 * dependencies, so just write the first one
3026 * in the hopes of eventually making progress.
3028 if (vp != NULL && target > 2)
3030 flushbufqueues(vp, target, 1);
3041 * This process needs to be suspended prior to shutdown sync.
3043 EVENTHANDLER_REGISTER(shutdown_pre_sync, kproc_shutdown, bufdaemonproc,
3047 * This process is allowed to take the buffer cache to the limit
3049 curthread->td_pflags |= TDP_NORUNNINGBUF | TDP_BUFNEED;
3053 mtx_unlock(&bdlock);
3055 kproc_suspend_check(bufdaemonproc);
3056 lodirty = lodirtybuffers;
3057 if (bd_speedupreq) {
3058 lodirty = numdirtybuffers / 2;
3062 * Do the flush. Limit the amount of in-transit I/O we
3063 * allow to build up, otherwise we would completely saturate
3066 while (numdirtybuffers > lodirty) {
3067 if (buf_flush(NULL, numdirtybuffers - lodirty) == 0)
3069 kern_yield(PRI_USER);
3073 * Only clear bd_request if we have reached our low water
3074 * mark. The buf_daemon normally waits 1 second and
3075 * then incrementally flushes any dirty buffers that have
3076 * built up, within reason.
3078 * If we were unable to hit our low water mark and couldn't
3079 * find any flushable buffers, we sleep for a short period
3080 * to avoid endless loops on unlockable buffers.
3083 if (numdirtybuffers <= lodirtybuffers) {
3085 * We reached our low water mark, reset the
3086 * request and sleep until we are needed again.
3087 * The sleep is just so the suspend code works.
3091 * Do an extra wakeup in case dirty threshold
3092 * changed via sysctl and the explicit transition
3093 * out of shortfall was missed.
3096 if (runningbufspace <= lorunningspace)
3098 msleep(&bd_request, &bdlock, PVM, "psleep", hz);
3101 * We couldn't find any flushable dirty buffers but
3102 * still have too many dirty buffers, we
3103 * have to sleep and try again. (rare)
3105 msleep(&bd_request, &bdlock, PVM, "qsleep", hz / 10);
3113 * Try to flush a buffer in the dirty queue. We must be careful to
3114 * free up B_INVAL buffers instead of write them, which NFS is
3115 * particularly sensitive to.
3117 static int flushwithdeps = 0;
3118 SYSCTL_INT(_vfs, OID_AUTO, flushwithdeps, CTLFLAG_RW, &flushwithdeps,
3119 0, "Number of buffers flushed with dependecies that require rollbacks");
3122 flushbufqueues(struct vnode *lvp, int target, int flushdeps)
3124 struct buf *sentinel;
3135 queue = QUEUE_DIRTY;
3137 sentinel = malloc(sizeof(struct buf), M_TEMP, M_WAITOK | M_ZERO);
3138 sentinel->b_qindex = QUEUE_SENTINEL;
3139 mtx_lock(&bqlocks[queue]);
3140 TAILQ_INSERT_HEAD(&bufqueues[queue], sentinel, b_freelist);
3141 mtx_unlock(&bqlocks[queue]);
3142 while (flushed != target) {
3144 mtx_lock(&bqlocks[queue]);
3145 bp = TAILQ_NEXT(sentinel, b_freelist);
3147 TAILQ_REMOVE(&bufqueues[queue], sentinel, b_freelist);
3148 TAILQ_INSERT_AFTER(&bufqueues[queue], bp, sentinel,
3151 mtx_unlock(&bqlocks[queue]);
3155 * Skip sentinels inserted by other invocations of the
3156 * flushbufqueues(), taking care to not reorder them.
3158 * Only flush the buffers that belong to the
3159 * vnode locked by the curthread.
3161 if (bp->b_qindex == QUEUE_SENTINEL || (lvp != NULL &&
3163 mtx_unlock(&bqlocks[queue]);
3166 error = BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL);
3167 mtx_unlock(&bqlocks[queue]);
3172 * BKGRDINPROG can only be set with the buf and bufobj
3173 * locks both held. We tolerate a race to clear it here.
3175 if ((bp->b_vflags & BV_BKGRDINPROG) != 0 ||
3176 (bp->b_flags & B_DELWRI) == 0) {
3180 if (bp->b_flags & B_INVAL) {
3187 if (!LIST_EMPTY(&bp->b_dep) && buf_countdeps(bp, 0)) {
3188 if (flushdeps == 0) {
3196 * We must hold the lock on a vnode before writing
3197 * one of its buffers. Otherwise we may confuse, or
3198 * in the case of a snapshot vnode, deadlock the
3201 * The lock order here is the reverse of the normal
3202 * of vnode followed by buf lock. This is ok because
3203 * the NOWAIT will prevent deadlock.
3206 if (vn_start_write(vp, &mp, V_NOWAIT) != 0) {
3212 error = vn_lock(vp, LK_EXCLUSIVE | LK_NOWAIT);
3214 ASSERT_VOP_LOCKED(vp, "getbuf");
3216 error = VOP_ISLOCKED(vp) == LK_EXCLUSIVE ? 0 :
3217 vn_lock(vp, LK_TRYUPGRADE);
3220 CTR3(KTR_BUF, "flushbufqueue(%p) vp %p flags %X",
3221 bp, bp->b_vp, bp->b_flags);
3222 if (curproc == bufdaemonproc) {
3229 vn_finished_write(mp);
3232 flushwithdeps += hasdeps;
3236 * Sleeping on runningbufspace while holding
3237 * vnode lock leads to deadlock.
3239 if (curproc == bufdaemonproc &&
3240 runningbufspace > hirunningspace)
3241 waitrunningbufspace();
3244 vn_finished_write(mp);
3247 mtx_lock(&bqlocks[queue]);
3248 TAILQ_REMOVE(&bufqueues[queue], sentinel, b_freelist);
3249 mtx_unlock(&bqlocks[queue]);
3250 free(sentinel, M_TEMP);
3255 * Check to see if a block is currently memory resident.
3258 incore(struct bufobj *bo, daddr_t blkno)
3263 bp = gbincore(bo, blkno);
3269 * Returns true if no I/O is needed to access the
3270 * associated VM object. This is like incore except
3271 * it also hunts around in the VM system for the data.
3275 inmem(struct vnode * vp, daddr_t blkno)
3278 vm_offset_t toff, tinc, size;
3282 ASSERT_VOP_LOCKED(vp, "inmem");
3284 if (incore(&vp->v_bufobj, blkno))
3286 if (vp->v_mount == NULL)
3293 if (size > vp->v_mount->mnt_stat.f_iosize)
3294 size = vp->v_mount->mnt_stat.f_iosize;
3295 off = (vm_ooffset_t)blkno * (vm_ooffset_t)vp->v_mount->mnt_stat.f_iosize;
3297 VM_OBJECT_RLOCK(obj);
3298 for (toff = 0; toff < vp->v_mount->mnt_stat.f_iosize; toff += tinc) {
3299 m = vm_page_lookup(obj, OFF_TO_IDX(off + toff));
3303 if (tinc > PAGE_SIZE - ((toff + off) & PAGE_MASK))
3304 tinc = PAGE_SIZE - ((toff + off) & PAGE_MASK);
3305 if (vm_page_is_valid(m,
3306 (vm_offset_t) ((toff + off) & PAGE_MASK), tinc) == 0)
3309 VM_OBJECT_RUNLOCK(obj);
3313 VM_OBJECT_RUNLOCK(obj);
3318 * Set the dirty range for a buffer based on the status of the dirty
3319 * bits in the pages comprising the buffer. The range is limited
3320 * to the size of the buffer.
3322 * Tell the VM system that the pages associated with this buffer
3323 * are clean. This is used for delayed writes where the data is
3324 * going to go to disk eventually without additional VM intevention.
3326 * Note that while we only really need to clean through to b_bcount, we
3327 * just go ahead and clean through to b_bufsize.
3330 vfs_clean_pages_dirty_buf(struct buf *bp)
3332 vm_ooffset_t foff, noff, eoff;
3336 if ((bp->b_flags & B_VMIO) == 0 || bp->b_bufsize == 0)
3339 foff = bp->b_offset;
3340 KASSERT(bp->b_offset != NOOFFSET,
3341 ("vfs_clean_pages_dirty_buf: no buffer offset"));
3343 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object);
3344 vfs_drain_busy_pages(bp);
3345 vfs_setdirty_locked_object(bp);
3346 for (i = 0; i < bp->b_npages; i++) {
3347 noff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK;
3349 if (eoff > bp->b_offset + bp->b_bufsize)
3350 eoff = bp->b_offset + bp->b_bufsize;
3352 vfs_page_set_validclean(bp, foff, m);
3353 /* vm_page_clear_dirty(m, foff & PAGE_MASK, eoff - foff); */
3356 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object);
3360 vfs_setdirty_locked_object(struct buf *bp)
3365 object = bp->b_bufobj->bo_object;
3366 VM_OBJECT_ASSERT_WLOCKED(object);
3369 * We qualify the scan for modified pages on whether the
3370 * object has been flushed yet.
3372 if ((object->flags & OBJ_MIGHTBEDIRTY) != 0) {
3373 vm_offset_t boffset;
3374 vm_offset_t eoffset;
3377 * test the pages to see if they have been modified directly
3378 * by users through the VM system.
3380 for (i = 0; i < bp->b_npages; i++)
3381 vm_page_test_dirty(bp->b_pages[i]);
3384 * Calculate the encompassing dirty range, boffset and eoffset,
3385 * (eoffset - boffset) bytes.
3388 for (i = 0; i < bp->b_npages; i++) {
3389 if (bp->b_pages[i]->dirty)
3392 boffset = (i << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK);
3394 for (i = bp->b_npages - 1; i >= 0; --i) {
3395 if (bp->b_pages[i]->dirty) {
3399 eoffset = ((i + 1) << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK);
3402 * Fit it to the buffer.
3405 if (eoffset > bp->b_bcount)
3406 eoffset = bp->b_bcount;
3409 * If we have a good dirty range, merge with the existing
3413 if (boffset < eoffset) {
3414 if (bp->b_dirtyoff > boffset)
3415 bp->b_dirtyoff = boffset;
3416 if (bp->b_dirtyend < eoffset)
3417 bp->b_dirtyend = eoffset;
3423 * Allocate the KVA mapping for an existing buffer.
3424 * If an unmapped buffer is provided but a mapped buffer is requested, take
3425 * also care to properly setup mappings between pages and KVA.
3428 bp_unmapped_get_kva(struct buf *bp, daddr_t blkno, int size, int gbflags)
3430 int bsize, maxsize, need_mapping, need_kva;
3433 need_mapping = bp->b_data == unmapped_buf &&
3434 (gbflags & GB_UNMAPPED) == 0;
3435 need_kva = bp->b_kvabase == unmapped_buf &&
3436 bp->b_data == unmapped_buf &&
3437 (gbflags & GB_KVAALLOC) != 0;
3438 if (!need_mapping && !need_kva)
3441 BUF_CHECK_UNMAPPED(bp);
3443 if (need_mapping && bp->b_kvabase != unmapped_buf) {
3445 * Buffer is not mapped, but the KVA was already
3446 * reserved at the time of the instantiation. Use the
3453 * Calculate the amount of the address space we would reserve
3454 * if the buffer was mapped.
3456 bsize = vn_isdisk(bp->b_vp, NULL) ? DEV_BSIZE : bp->b_bufobj->bo_bsize;
3457 KASSERT(bsize != 0, ("bsize == 0, check bo->bo_bsize"));
3458 offset = blkno * bsize;
3459 maxsize = size + (offset & PAGE_MASK);
3460 maxsize = imax(maxsize, bsize);
3462 while (bufkva_alloc(bp, maxsize, gbflags) != 0) {
3463 if ((gbflags & GB_NOWAIT_BD) != 0) {
3465 * XXXKIB: defragmentation cannot
3466 * succeed, not sure what else to do.
3468 panic("GB_NOWAIT_BD and GB_UNMAPPED %p", bp);
3470 atomic_add_int(&mappingrestarts, 1);
3471 bufspace_wait(bp->b_vp, gbflags, 0, 0);
3475 /* b_offset is handled by bpmap_qenter. */
3476 bp->b_data = bp->b_kvabase;
3477 BUF_CHECK_MAPPED(bp);
3485 * Get a block given a specified block and offset into a file/device.
3486 * The buffers B_DONE bit will be cleared on return, making it almost
3487 * ready for an I/O initiation. B_INVAL may or may not be set on
3488 * return. The caller should clear B_INVAL prior to initiating a
3491 * For a non-VMIO buffer, B_CACHE is set to the opposite of B_INVAL for
3492 * an existing buffer.
3494 * For a VMIO buffer, B_CACHE is modified according to the backing VM.
3495 * If getblk()ing a previously 0-sized invalid buffer, B_CACHE is set
3496 * and then cleared based on the backing VM. If the previous buffer is
3497 * non-0-sized but invalid, B_CACHE will be cleared.
3499 * If getblk() must create a new buffer, the new buffer is returned with
3500 * both B_INVAL and B_CACHE clear unless it is a VMIO buffer, in which
3501 * case it is returned with B_INVAL clear and B_CACHE set based on the
3504 * getblk() also forces a bwrite() for any B_DELWRI buffer whos
3505 * B_CACHE bit is clear.
3507 * What this means, basically, is that the caller should use B_CACHE to
3508 * determine whether the buffer is fully valid or not and should clear
3509 * B_INVAL prior to issuing a read. If the caller intends to validate
3510 * the buffer by loading its data area with something, the caller needs
3511 * to clear B_INVAL. If the caller does this without issuing an I/O,
3512 * the caller should set B_CACHE ( as an optimization ), else the caller
3513 * should issue the I/O and biodone() will set B_CACHE if the I/O was
3514 * a write attempt or if it was a successful read. If the caller
3515 * intends to issue a READ, the caller must clear B_INVAL and BIO_ERROR
3516 * prior to issuing the READ. biodone() will *not* clear B_INVAL.
3519 getblk(struct vnode *vp, daddr_t blkno, int size, int slpflag, int slptimeo,
3524 int bsize, error, maxsize, vmio;
3527 CTR3(KTR_BUF, "getblk(%p, %ld, %d)", vp, (long)blkno, size);
3528 KASSERT((flags & (GB_UNMAPPED | GB_KVAALLOC)) != GB_KVAALLOC,
3529 ("GB_KVAALLOC only makes sense with GB_UNMAPPED"));
3530 ASSERT_VOP_LOCKED(vp, "getblk");
3531 if (size > maxbcachebuf)
3532 panic("getblk: size(%d) > maxbcachebuf(%d)\n", size,
3534 if (!unmapped_buf_allowed)
3535 flags &= ~(GB_UNMAPPED | GB_KVAALLOC);
3540 bp = gbincore(bo, blkno);
3544 * Buffer is in-core. If the buffer is not busy nor managed,
3545 * it must be on a queue.
3547 lockflags = LK_EXCLUSIVE | LK_SLEEPFAIL | LK_INTERLOCK;
3549 if (flags & GB_LOCK_NOWAIT)
3550 lockflags |= LK_NOWAIT;
3552 error = BUF_TIMELOCK(bp, lockflags,
3553 BO_LOCKPTR(bo), "getblk", slpflag, slptimeo);
3556 * If we slept and got the lock we have to restart in case
3557 * the buffer changed identities.
3559 if (error == ENOLCK)
3561 /* We timed out or were interrupted. */
3564 /* If recursed, assume caller knows the rules. */
3565 else if (BUF_LOCKRECURSED(bp))
3569 * The buffer is locked. B_CACHE is cleared if the buffer is
3570 * invalid. Otherwise, for a non-VMIO buffer, B_CACHE is set
3571 * and for a VMIO buffer B_CACHE is adjusted according to the
3574 if (bp->b_flags & B_INVAL)
3575 bp->b_flags &= ~B_CACHE;
3576 else if ((bp->b_flags & (B_VMIO | B_INVAL)) == 0)
3577 bp->b_flags |= B_CACHE;
3578 if (bp->b_flags & B_MANAGED)
3579 MPASS(bp->b_qindex == QUEUE_NONE);
3584 * check for size inconsistencies for non-VMIO case.
3586 if (bp->b_bcount != size) {
3587 if ((bp->b_flags & B_VMIO) == 0 ||
3588 (size > bp->b_kvasize)) {
3589 if (bp->b_flags & B_DELWRI) {
3590 bp->b_flags |= B_NOCACHE;
3593 if (LIST_EMPTY(&bp->b_dep)) {
3594 bp->b_flags |= B_RELBUF;
3597 bp->b_flags |= B_NOCACHE;
3606 * Handle the case of unmapped buffer which should
3607 * become mapped, or the buffer for which KVA
3608 * reservation is requested.
3610 bp_unmapped_get_kva(bp, blkno, size, flags);
3613 * If the size is inconsistent in the VMIO case, we can resize
3614 * the buffer. This might lead to B_CACHE getting set or
3615 * cleared. If the size has not changed, B_CACHE remains
3616 * unchanged from its previous state.
3620 KASSERT(bp->b_offset != NOOFFSET,
3621 ("getblk: no buffer offset"));
3624 * A buffer with B_DELWRI set and B_CACHE clear must
3625 * be committed before we can return the buffer in
3626 * order to prevent the caller from issuing a read
3627 * ( due to B_CACHE not being set ) and overwriting
3630 * Most callers, including NFS and FFS, need this to
3631 * operate properly either because they assume they
3632 * can issue a read if B_CACHE is not set, or because
3633 * ( for example ) an uncached B_DELWRI might loop due
3634 * to softupdates re-dirtying the buffer. In the latter
3635 * case, B_CACHE is set after the first write completes,
3636 * preventing further loops.
3637 * NOTE! b*write() sets B_CACHE. If we cleared B_CACHE
3638 * above while extending the buffer, we cannot allow the
3639 * buffer to remain with B_CACHE set after the write
3640 * completes or it will represent a corrupt state. To
3641 * deal with this we set B_NOCACHE to scrap the buffer
3644 * We might be able to do something fancy, like setting
3645 * B_CACHE in bwrite() except if B_DELWRI is already set,
3646 * so the below call doesn't set B_CACHE, but that gets real
3647 * confusing. This is much easier.
3650 if ((bp->b_flags & (B_CACHE|B_DELWRI)) == B_DELWRI) {
3651 bp->b_flags |= B_NOCACHE;
3655 bp->b_flags &= ~B_DONE;
3658 * Buffer is not in-core, create new buffer. The buffer
3659 * returned by getnewbuf() is locked. Note that the returned
3660 * buffer is also considered valid (not marked B_INVAL).
3664 * If the user does not want us to create the buffer, bail out
3667 if (flags & GB_NOCREAT)
3669 if (numfreebuffers == 0 && TD_IS_IDLETHREAD(curthread))
3672 bsize = vn_isdisk(vp, NULL) ? DEV_BSIZE : bo->bo_bsize;
3673 KASSERT(bsize != 0, ("bsize == 0, check bo->bo_bsize"));
3674 offset = blkno * bsize;
3675 vmio = vp->v_object != NULL;
3677 maxsize = size + (offset & PAGE_MASK);
3680 /* Do not allow non-VMIO notmapped buffers. */
3681 flags &= ~(GB_UNMAPPED | GB_KVAALLOC);
3683 maxsize = imax(maxsize, bsize);
3685 bp = getnewbuf(vp, slpflag, slptimeo, maxsize, flags);
3687 if (slpflag || slptimeo)
3690 * XXX This is here until the sleep path is diagnosed
3691 * enough to work under very low memory conditions.
3693 * There's an issue on low memory, 4BSD+non-preempt
3694 * systems (eg MIPS routers with 32MB RAM) where buffer
3695 * exhaustion occurs without sleeping for buffer
3696 * reclaimation. This just sticks in a loop and
3697 * constantly attempts to allocate a buffer, which
3698 * hits exhaustion and tries to wakeup bufdaemon.
3699 * This never happens because we never yield.
3701 * The real solution is to identify and fix these cases
3702 * so we aren't effectively busy-waiting in a loop
3703 * until the reclaimation path has cycles to run.
3705 kern_yield(PRI_USER);
3710 * This code is used to make sure that a buffer is not
3711 * created while the getnewbuf routine is blocked.
3712 * This can be a problem whether the vnode is locked or not.
3713 * If the buffer is created out from under us, we have to
3714 * throw away the one we just created.
3716 * Note: this must occur before we associate the buffer
3717 * with the vp especially considering limitations in
3718 * the splay tree implementation when dealing with duplicate
3722 if (gbincore(bo, blkno)) {
3724 bp->b_flags |= B_INVAL;
3726 bufspace_release(maxsize);
3731 * Insert the buffer into the hash, so that it can
3732 * be found by incore.
3734 bp->b_blkno = bp->b_lblkno = blkno;
3735 bp->b_offset = offset;
3740 * set B_VMIO bit. allocbuf() the buffer bigger. Since the
3741 * buffer size starts out as 0, B_CACHE will be set by
3742 * allocbuf() for the VMIO case prior to it testing the
3743 * backing store for validity.
3747 bp->b_flags |= B_VMIO;
3748 KASSERT(vp->v_object == bp->b_bufobj->bo_object,
3749 ("ARGH! different b_bufobj->bo_object %p %p %p\n",
3750 bp, vp->v_object, bp->b_bufobj->bo_object));
3752 bp->b_flags &= ~B_VMIO;
3753 KASSERT(bp->b_bufobj->bo_object == NULL,
3754 ("ARGH! has b_bufobj->bo_object %p %p\n",
3755 bp, bp->b_bufobj->bo_object));
3756 BUF_CHECK_MAPPED(bp);
3760 bufspace_release(maxsize);
3761 bp->b_flags &= ~B_DONE;
3763 CTR4(KTR_BUF, "getblk(%p, %ld, %d) = %p", vp, (long)blkno, size, bp);
3764 BUF_ASSERT_HELD(bp);
3766 buf_track(bp, __func__);
3767 KASSERT(bp->b_bufobj == bo,
3768 ("bp %p wrong b_bufobj %p should be %p", bp, bp->b_bufobj, bo));
3773 * Get an empty, disassociated buffer of given size. The buffer is initially
3777 geteblk(int size, int flags)
3782 maxsize = (size + BKVAMASK) & ~BKVAMASK;
3783 while ((bp = getnewbuf(NULL, 0, 0, maxsize, flags)) == NULL) {
3784 if ((flags & GB_NOWAIT_BD) &&
3785 (curthread->td_pflags & TDP_BUFNEED) != 0)
3789 bufspace_release(maxsize);
3790 bp->b_flags |= B_INVAL; /* b_dep cleared by getnewbuf() */
3791 BUF_ASSERT_HELD(bp);
3796 * Truncate the backing store for a non-vmio buffer.
3799 vfs_nonvmio_truncate(struct buf *bp, int newbsize)
3802 if (bp->b_flags & B_MALLOC) {
3804 * malloced buffers are not shrunk
3806 if (newbsize == 0) {
3807 bufmallocadjust(bp, 0);
3808 free(bp->b_data, M_BIOBUF);
3809 bp->b_data = bp->b_kvabase;
3810 bp->b_flags &= ~B_MALLOC;
3814 vm_hold_free_pages(bp, newbsize);
3815 bufspace_adjust(bp, newbsize);
3819 * Extend the backing for a non-VMIO buffer.
3822 vfs_nonvmio_extend(struct buf *bp, int newbsize)
3828 * We only use malloced memory on the first allocation.
3829 * and revert to page-allocated memory when the buffer
3832 * There is a potential smp race here that could lead
3833 * to bufmallocspace slightly passing the max. It
3834 * is probably extremely rare and not worth worrying
3837 if (bp->b_bufsize == 0 && newbsize <= PAGE_SIZE/2 &&
3838 bufmallocspace < maxbufmallocspace) {
3839 bp->b_data = malloc(newbsize, M_BIOBUF, M_WAITOK);
3840 bp->b_flags |= B_MALLOC;
3841 bufmallocadjust(bp, newbsize);
3846 * If the buffer is growing on its other-than-first
3847 * allocation then we revert to the page-allocation
3852 if (bp->b_flags & B_MALLOC) {
3853 origbuf = bp->b_data;
3854 origbufsize = bp->b_bufsize;
3855 bp->b_data = bp->b_kvabase;
3856 bufmallocadjust(bp, 0);
3857 bp->b_flags &= ~B_MALLOC;
3858 newbsize = round_page(newbsize);
3860 vm_hold_load_pages(bp, (vm_offset_t) bp->b_data + bp->b_bufsize,
3861 (vm_offset_t) bp->b_data + newbsize);
3862 if (origbuf != NULL) {
3863 bcopy(origbuf, bp->b_data, origbufsize);
3864 free(origbuf, M_BIOBUF);
3866 bufspace_adjust(bp, newbsize);
3870 * This code constitutes the buffer memory from either anonymous system
3871 * memory (in the case of non-VMIO operations) or from an associated
3872 * VM object (in the case of VMIO operations). This code is able to
3873 * resize a buffer up or down.
3875 * Note that this code is tricky, and has many complications to resolve
3876 * deadlock or inconsistent data situations. Tread lightly!!!
3877 * There are B_CACHE and B_DELWRI interactions that must be dealt with by
3878 * the caller. Calling this code willy nilly can result in the loss of data.
3880 * allocbuf() only adjusts B_CACHE for VMIO buffers. getblk() deals with
3881 * B_CACHE for the non-VMIO case.
3884 allocbuf(struct buf *bp, int size)
3888 BUF_ASSERT_HELD(bp);
3890 if (bp->b_bcount == size)
3893 if (bp->b_kvasize != 0 && bp->b_kvasize < size)
3894 panic("allocbuf: buffer too small");
3896 newbsize = roundup2(size, DEV_BSIZE);
3897 if ((bp->b_flags & B_VMIO) == 0) {
3898 if ((bp->b_flags & B_MALLOC) == 0)
3899 newbsize = round_page(newbsize);
3901 * Just get anonymous memory from the kernel. Don't
3902 * mess with B_CACHE.
3904 if (newbsize < bp->b_bufsize)
3905 vfs_nonvmio_truncate(bp, newbsize);
3906 else if (newbsize > bp->b_bufsize)
3907 vfs_nonvmio_extend(bp, newbsize);
3911 desiredpages = (size == 0) ? 0 :
3912 num_pages((bp->b_offset & PAGE_MASK) + newbsize);
3914 if (bp->b_flags & B_MALLOC)
3915 panic("allocbuf: VMIO buffer can't be malloced");
3917 * Set B_CACHE initially if buffer is 0 length or will become
3920 if (size == 0 || bp->b_bufsize == 0)
3921 bp->b_flags |= B_CACHE;
3923 if (newbsize < bp->b_bufsize)
3924 vfs_vmio_truncate(bp, desiredpages);
3925 /* XXX This looks as if it should be newbsize > b_bufsize */
3926 else if (size > bp->b_bcount)
3927 vfs_vmio_extend(bp, desiredpages, size);
3928 bufspace_adjust(bp, newbsize);
3930 bp->b_bcount = size; /* requested buffer size. */
3934 extern int inflight_transient_maps;
3937 biodone(struct bio *bp)
3940 void (*done)(struct bio *);
3941 vm_offset_t start, end;
3943 biotrack(bp, __func__);
3944 if ((bp->bio_flags & BIO_TRANSIENT_MAPPING) != 0) {
3945 bp->bio_flags &= ~BIO_TRANSIENT_MAPPING;
3946 bp->bio_flags |= BIO_UNMAPPED;
3947 start = trunc_page((vm_offset_t)bp->bio_data);
3948 end = round_page((vm_offset_t)bp->bio_data + bp->bio_length);
3949 bp->bio_data = unmapped_buf;
3950 pmap_qremove(start, atop(end - start));
3951 vmem_free(transient_arena, start, end - start);
3952 atomic_add_int(&inflight_transient_maps, -1);
3954 done = bp->bio_done;
3956 mtxp = mtx_pool_find(mtxpool_sleep, bp);
3958 bp->bio_flags |= BIO_DONE;
3966 * Wait for a BIO to finish.
3969 biowait(struct bio *bp, const char *wchan)
3973 mtxp = mtx_pool_find(mtxpool_sleep, bp);
3975 while ((bp->bio_flags & BIO_DONE) == 0)
3976 msleep(bp, mtxp, PRIBIO, wchan, 0);
3978 if (bp->bio_error != 0)
3979 return (bp->bio_error);
3980 if (!(bp->bio_flags & BIO_ERROR))
3986 biofinish(struct bio *bp, struct devstat *stat, int error)
3990 bp->bio_error = error;
3991 bp->bio_flags |= BIO_ERROR;
3994 devstat_end_transaction_bio(stat, bp);
3998 #if defined(BUF_TRACKING) || defined(FULL_BUF_TRACKING)
4000 biotrack_buf(struct bio *bp, const char *location)
4003 buf_track(bp->bio_track_bp, location);
4010 * Wait for buffer I/O completion, returning error status. The buffer
4011 * is left locked and B_DONE on return. B_EINTR is converted into an EINTR
4012 * error and cleared.
4015 bufwait(struct buf *bp)
4017 if (bp->b_iocmd == BIO_READ)
4018 bwait(bp, PRIBIO, "biord");
4020 bwait(bp, PRIBIO, "biowr");
4021 if (bp->b_flags & B_EINTR) {
4022 bp->b_flags &= ~B_EINTR;
4025 if (bp->b_ioflags & BIO_ERROR) {
4026 return (bp->b_error ? bp->b_error : EIO);
4035 * Finish I/O on a buffer, optionally calling a completion function.
4036 * This is usually called from an interrupt so process blocking is
4039 * biodone is also responsible for setting B_CACHE in a B_VMIO bp.
4040 * In a non-VMIO bp, B_CACHE will be set on the next getblk()
4041 * assuming B_INVAL is clear.
4043 * For the VMIO case, we set B_CACHE if the op was a read and no
4044 * read error occurred, or if the op was a write. B_CACHE is never
4045 * set if the buffer is invalid or otherwise uncacheable.
4047 * biodone does not mess with B_INVAL, allowing the I/O routine or the
4048 * initiator to leave B_INVAL set to brelse the buffer out of existence
4049 * in the biodone routine.
4052 bufdone(struct buf *bp)
4054 struct bufobj *dropobj;
4055 void (*biodone)(struct buf *);
4057 buf_track(bp, __func__);
4058 CTR3(KTR_BUF, "bufdone(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
4061 KASSERT(!(bp->b_flags & B_DONE), ("biodone: bp %p already done", bp));
4062 BUF_ASSERT_HELD(bp);
4064 runningbufwakeup(bp);
4065 if (bp->b_iocmd == BIO_WRITE)
4066 dropobj = bp->b_bufobj;
4067 else if ((bp->b_flags & B_CKHASH) != 0) {
4068 KASSERT(buf_mapped(bp), ("biodone: bp %p not mapped", bp));
4069 (*bp->b_ckhashcalc)(bp);
4071 /* call optional completion function if requested */
4072 if (bp->b_iodone != NULL) {
4073 biodone = bp->b_iodone;
4074 bp->b_iodone = NULL;
4077 bufobj_wdrop(dropobj);
4084 bufobj_wdrop(dropobj);
4088 bufdone_finish(struct buf *bp)
4090 BUF_ASSERT_HELD(bp);
4092 if (!LIST_EMPTY(&bp->b_dep))
4095 if (bp->b_flags & B_VMIO) {
4097 * Set B_CACHE if the op was a normal read and no error
4098 * occurred. B_CACHE is set for writes in the b*write()
4101 if (bp->b_iocmd == BIO_READ &&
4102 !(bp->b_flags & (B_INVAL|B_NOCACHE)) &&
4103 !(bp->b_ioflags & BIO_ERROR))
4104 bp->b_flags |= B_CACHE;
4105 vfs_vmio_iodone(bp);
4109 * For asynchronous completions, release the buffer now. The brelse
4110 * will do a wakeup there if necessary - so no need to do a wakeup
4111 * here in the async case. The sync case always needs to do a wakeup.
4113 if (bp->b_flags & B_ASYNC) {
4114 if ((bp->b_flags & (B_NOCACHE | B_INVAL | B_RELBUF)) ||
4115 (bp->b_ioflags & BIO_ERROR))
4124 * This routine is called in lieu of iodone in the case of
4125 * incomplete I/O. This keeps the busy status for pages
4129 vfs_unbusy_pages(struct buf *bp)
4135 runningbufwakeup(bp);
4136 if (!(bp->b_flags & B_VMIO))
4139 obj = bp->b_bufobj->bo_object;
4140 VM_OBJECT_WLOCK(obj);
4141 for (i = 0; i < bp->b_npages; i++) {
4143 if (m == bogus_page) {
4144 m = vm_page_lookup(obj, OFF_TO_IDX(bp->b_offset) + i);
4146 panic("vfs_unbusy_pages: page missing\n");
4148 if (buf_mapped(bp)) {
4149 BUF_CHECK_MAPPED(bp);
4150 pmap_qenter(trunc_page((vm_offset_t)bp->b_data),
4151 bp->b_pages, bp->b_npages);
4153 BUF_CHECK_UNMAPPED(bp);
4157 vm_object_pip_wakeupn(obj, bp->b_npages);
4158 VM_OBJECT_WUNLOCK(obj);
4162 * vfs_page_set_valid:
4164 * Set the valid bits in a page based on the supplied offset. The
4165 * range is restricted to the buffer's size.
4167 * This routine is typically called after a read completes.
4170 vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, vm_page_t m)
4175 * Compute the end offset, eoff, such that [off, eoff) does not span a
4176 * page boundary and eoff is not greater than the end of the buffer.
4177 * The end of the buffer, in this case, is our file EOF, not the
4178 * allocation size of the buffer.
4180 eoff = (off + PAGE_SIZE) & ~(vm_ooffset_t)PAGE_MASK;
4181 if (eoff > bp->b_offset + bp->b_bcount)
4182 eoff = bp->b_offset + bp->b_bcount;
4185 * Set valid range. This is typically the entire buffer and thus the
4189 vm_page_set_valid_range(m, off & PAGE_MASK, eoff - off);
4193 * vfs_page_set_validclean:
4195 * Set the valid bits and clear the dirty bits in a page based on the
4196 * supplied offset. The range is restricted to the buffer's size.
4199 vfs_page_set_validclean(struct buf *bp, vm_ooffset_t off, vm_page_t m)
4201 vm_ooffset_t soff, eoff;
4204 * Start and end offsets in buffer. eoff - soff may not cross a
4205 * page boundary or cross the end of the buffer. The end of the
4206 * buffer, in this case, is our file EOF, not the allocation size
4210 eoff = (off + PAGE_SIZE) & ~(off_t)PAGE_MASK;
4211 if (eoff > bp->b_offset + bp->b_bcount)
4212 eoff = bp->b_offset + bp->b_bcount;
4215 * Set valid range. This is typically the entire buffer and thus the
4219 vm_page_set_validclean(
4221 (vm_offset_t) (soff & PAGE_MASK),
4222 (vm_offset_t) (eoff - soff)
4228 * Ensure that all buffer pages are not exclusive busied. If any page is
4229 * exclusive busy, drain it.
4232 vfs_drain_busy_pages(struct buf *bp)
4237 VM_OBJECT_ASSERT_WLOCKED(bp->b_bufobj->bo_object);
4239 for (i = 0; i < bp->b_npages; i++) {
4241 if (vm_page_xbusied(m)) {
4242 for (; last_busied < i; last_busied++)
4243 vm_page_sbusy(bp->b_pages[last_busied]);
4244 while (vm_page_xbusied(m)) {
4246 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object);
4247 vm_page_busy_sleep(m, "vbpage", true);
4248 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object);
4252 for (i = 0; i < last_busied; i++)
4253 vm_page_sunbusy(bp->b_pages[i]);
4257 * This routine is called before a device strategy routine.
4258 * It is used to tell the VM system that paging I/O is in
4259 * progress, and treat the pages associated with the buffer
4260 * almost as being exclusive busy. Also the object paging_in_progress
4261 * flag is handled to make sure that the object doesn't become
4264 * Since I/O has not been initiated yet, certain buffer flags
4265 * such as BIO_ERROR or B_INVAL may be in an inconsistent state
4266 * and should be ignored.
4269 vfs_busy_pages(struct buf *bp, int clear_modify)
4277 if (!(bp->b_flags & B_VMIO))
4280 obj = bp->b_bufobj->bo_object;
4281 foff = bp->b_offset;
4282 KASSERT(bp->b_offset != NOOFFSET,
4283 ("vfs_busy_pages: no buffer offset"));
4284 VM_OBJECT_WLOCK(obj);
4285 vfs_drain_busy_pages(bp);
4286 if (bp->b_bufsize != 0)
4287 vfs_setdirty_locked_object(bp);
4289 for (i = 0; i < bp->b_npages; i++) {
4292 if ((bp->b_flags & B_CLUSTER) == 0) {
4293 vm_object_pip_add(obj, 1);
4297 * When readying a buffer for a read ( i.e
4298 * clear_modify == 0 ), it is important to do
4299 * bogus_page replacement for valid pages in
4300 * partially instantiated buffers. Partially
4301 * instantiated buffers can, in turn, occur when
4302 * reconstituting a buffer from its VM backing store
4303 * base. We only have to do this if B_CACHE is
4304 * clear ( which causes the I/O to occur in the
4305 * first place ). The replacement prevents the read
4306 * I/O from overwriting potentially dirty VM-backed
4307 * pages. XXX bogus page replacement is, uh, bogus.
4308 * It may not work properly with small-block devices.
4309 * We need to find a better way.
4312 pmap_remove_write(m);
4313 vfs_page_set_validclean(bp, foff, m);
4314 } else if (m->valid == VM_PAGE_BITS_ALL &&
4315 (bp->b_flags & B_CACHE) == 0) {
4316 bp->b_pages[i] = bogus_page;
4319 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK;
4321 VM_OBJECT_WUNLOCK(obj);
4322 if (bogus && buf_mapped(bp)) {
4323 BUF_CHECK_MAPPED(bp);
4324 pmap_qenter(trunc_page((vm_offset_t)bp->b_data),
4325 bp->b_pages, bp->b_npages);
4330 * vfs_bio_set_valid:
4332 * Set the range within the buffer to valid. The range is
4333 * relative to the beginning of the buffer, b_offset. Note that
4334 * b_offset itself may be offset from the beginning of the first
4338 vfs_bio_set_valid(struct buf *bp, int base, int size)
4343 if (!(bp->b_flags & B_VMIO))
4347 * Fixup base to be relative to beginning of first page.
4348 * Set initial n to be the maximum number of bytes in the
4349 * first page that can be validated.
4351 base += (bp->b_offset & PAGE_MASK);
4352 n = PAGE_SIZE - (base & PAGE_MASK);
4354 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object);
4355 for (i = base / PAGE_SIZE; size > 0 && i < bp->b_npages; ++i) {
4359 vm_page_set_valid_range(m, base & PAGE_MASK, n);
4364 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object);
4370 * If the specified buffer is a non-VMIO buffer, clear the entire
4371 * buffer. If the specified buffer is a VMIO buffer, clear and
4372 * validate only the previously invalid portions of the buffer.
4373 * This routine essentially fakes an I/O, so we need to clear
4374 * BIO_ERROR and B_INVAL.
4376 * Note that while we only theoretically need to clear through b_bcount,
4377 * we go ahead and clear through b_bufsize.
4380 vfs_bio_clrbuf(struct buf *bp)
4382 int i, j, mask, sa, ea, slide;
4384 if ((bp->b_flags & (B_VMIO | B_MALLOC)) != B_VMIO) {
4388 bp->b_flags &= ~B_INVAL;
4389 bp->b_ioflags &= ~BIO_ERROR;
4390 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object);
4391 if ((bp->b_npages == 1) && (bp->b_bufsize < PAGE_SIZE) &&
4392 (bp->b_offset & PAGE_MASK) == 0) {
4393 if (bp->b_pages[0] == bogus_page)
4395 mask = (1 << (bp->b_bufsize / DEV_BSIZE)) - 1;
4396 VM_OBJECT_ASSERT_WLOCKED(bp->b_pages[0]->object);
4397 if ((bp->b_pages[0]->valid & mask) == mask)
4399 if ((bp->b_pages[0]->valid & mask) == 0) {
4400 pmap_zero_page_area(bp->b_pages[0], 0, bp->b_bufsize);
4401 bp->b_pages[0]->valid |= mask;
4405 sa = bp->b_offset & PAGE_MASK;
4407 for (i = 0; i < bp->b_npages; i++, sa = 0) {
4408 slide = imin(slide + PAGE_SIZE, bp->b_offset + bp->b_bufsize);
4409 ea = slide & PAGE_MASK;
4412 if (bp->b_pages[i] == bogus_page)
4415 mask = ((1 << ((ea - sa) / DEV_BSIZE)) - 1) << j;
4416 VM_OBJECT_ASSERT_WLOCKED(bp->b_pages[i]->object);
4417 if ((bp->b_pages[i]->valid & mask) == mask)
4419 if ((bp->b_pages[i]->valid & mask) == 0)
4420 pmap_zero_page_area(bp->b_pages[i], sa, ea - sa);
4422 for (; sa < ea; sa += DEV_BSIZE, j++) {
4423 if ((bp->b_pages[i]->valid & (1 << j)) == 0) {
4424 pmap_zero_page_area(bp->b_pages[i],
4429 bp->b_pages[i]->valid |= mask;
4432 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object);
4437 vfs_bio_bzero_buf(struct buf *bp, int base, int size)
4442 if (buf_mapped(bp)) {
4443 BUF_CHECK_MAPPED(bp);
4444 bzero(bp->b_data + base, size);
4446 BUF_CHECK_UNMAPPED(bp);
4447 n = PAGE_SIZE - (base & PAGE_MASK);
4448 for (i = base / PAGE_SIZE; size > 0 && i < bp->b_npages; ++i) {
4452 pmap_zero_page_area(m, base & PAGE_MASK, n);
4461 * Update buffer flags based on I/O request parameters, optionally releasing the
4462 * buffer. If it's VMIO or direct I/O, the buffer pages are released to the VM,
4463 * where they may be placed on a page queue (VMIO) or freed immediately (direct
4464 * I/O). Otherwise the buffer is released to the cache.
4467 b_io_dismiss(struct buf *bp, int ioflag, bool release)
4470 KASSERT((ioflag & IO_NOREUSE) == 0 || (ioflag & IO_VMIO) != 0,
4471 ("buf %p non-VMIO noreuse", bp));
4473 if ((ioflag & IO_DIRECT) != 0)
4474 bp->b_flags |= B_DIRECT;
4475 if ((ioflag & (IO_VMIO | IO_DIRECT)) != 0 && LIST_EMPTY(&bp->b_dep)) {
4476 bp->b_flags |= B_RELBUF;
4477 if ((ioflag & IO_NOREUSE) != 0)
4478 bp->b_flags |= B_NOREUSE;
4486 vfs_bio_brelse(struct buf *bp, int ioflag)
4489 b_io_dismiss(bp, ioflag, true);
4493 vfs_bio_set_flags(struct buf *bp, int ioflag)
4496 b_io_dismiss(bp, ioflag, false);
4500 * vm_hold_load_pages and vm_hold_free_pages get pages into
4501 * a buffers address space. The pages are anonymous and are
4502 * not associated with a file object.
4505 vm_hold_load_pages(struct buf *bp, vm_offset_t from, vm_offset_t to)
4511 BUF_CHECK_MAPPED(bp);
4513 to = round_page(to);
4514 from = round_page(from);
4515 index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT;
4517 for (pg = from; pg < to; pg += PAGE_SIZE, index++) {
4519 * note: must allocate system pages since blocking here
4520 * could interfere with paging I/O, no matter which
4523 p = vm_page_alloc(NULL, 0, VM_ALLOC_SYSTEM | VM_ALLOC_NOOBJ |
4524 VM_ALLOC_WIRED | VM_ALLOC_COUNT((to - pg) >> PAGE_SHIFT) |
4526 pmap_qenter(pg, &p, 1);
4527 bp->b_pages[index] = p;
4529 bp->b_npages = index;
4532 /* Return pages associated with this buf to the vm system */
4534 vm_hold_free_pages(struct buf *bp, int newbsize)
4538 int index, newnpages;
4540 BUF_CHECK_MAPPED(bp);
4542 from = round_page((vm_offset_t)bp->b_data + newbsize);
4543 newnpages = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT;
4544 if (bp->b_npages > newnpages)
4545 pmap_qremove(from, bp->b_npages - newnpages);
4546 for (index = newnpages; index < bp->b_npages; index++) {
4547 p = bp->b_pages[index];
4548 bp->b_pages[index] = NULL;
4552 atomic_subtract_int(&vm_cnt.v_wire_count, bp->b_npages - newnpages);
4553 bp->b_npages = newnpages;
4557 * Map an IO request into kernel virtual address space.
4559 * All requests are (re)mapped into kernel VA space.
4560 * Notice that we use b_bufsize for the size of the buffer
4561 * to be mapped. b_bcount might be modified by the driver.
4563 * Note that even if the caller determines that the address space should
4564 * be valid, a race or a smaller-file mapped into a larger space may
4565 * actually cause vmapbuf() to fail, so all callers of vmapbuf() MUST
4566 * check the return value.
4568 * This function only works with pager buffers.
4571 vmapbuf(struct buf *bp, int mapbuf)
4576 if (bp->b_bufsize < 0)
4578 prot = VM_PROT_READ;
4579 if (bp->b_iocmd == BIO_READ)
4580 prot |= VM_PROT_WRITE; /* Less backwards than it looks */
4581 if ((pidx = vm_fault_quick_hold_pages(&curproc->p_vmspace->vm_map,
4582 (vm_offset_t)bp->b_data, bp->b_bufsize, prot, bp->b_pages,
4583 btoc(MAXPHYS))) < 0)
4585 bp->b_npages = pidx;
4586 bp->b_offset = ((vm_offset_t)bp->b_data) & PAGE_MASK;
4587 if (mapbuf || !unmapped_buf_allowed) {
4588 pmap_qenter((vm_offset_t)bp->b_kvabase, bp->b_pages, pidx);
4589 bp->b_data = bp->b_kvabase + bp->b_offset;
4591 bp->b_data = unmapped_buf;
4596 * Free the io map PTEs associated with this IO operation.
4597 * We also invalidate the TLB entries and restore the original b_addr.
4599 * This function only works with pager buffers.
4602 vunmapbuf(struct buf *bp)
4606 npages = bp->b_npages;
4608 pmap_qremove(trunc_page((vm_offset_t)bp->b_data), npages);
4609 vm_page_unhold_pages(bp->b_pages, npages);
4611 bp->b_data = unmapped_buf;
4615 bdone(struct buf *bp)
4619 mtxp = mtx_pool_find(mtxpool_sleep, bp);
4621 bp->b_flags |= B_DONE;
4627 bwait(struct buf *bp, u_char pri, const char *wchan)
4631 mtxp = mtx_pool_find(mtxpool_sleep, bp);
4633 while ((bp->b_flags & B_DONE) == 0)
4634 msleep(bp, mtxp, pri, wchan, 0);
4639 bufsync(struct bufobj *bo, int waitfor)
4642 return (VOP_FSYNC(bo2vnode(bo), waitfor, curthread));
4646 bufstrategy(struct bufobj *bo, struct buf *bp)
4652 KASSERT(vp == bo->bo_private, ("Inconsistent vnode bufstrategy"));
4653 KASSERT(vp->v_type != VCHR && vp->v_type != VBLK,
4654 ("Wrong vnode in bufstrategy(bp=%p, vp=%p)", bp, vp));
4655 i = VOP_STRATEGY(vp, bp);
4656 KASSERT(i == 0, ("VOP_STRATEGY failed bp=%p vp=%p", bp, bp->b_vp));
4660 bufobj_wrefl(struct bufobj *bo)
4663 KASSERT(bo != NULL, ("NULL bo in bufobj_wref"));
4664 ASSERT_BO_WLOCKED(bo);
4669 bufobj_wref(struct bufobj *bo)
4672 KASSERT(bo != NULL, ("NULL bo in bufobj_wref"));
4679 bufobj_wdrop(struct bufobj *bo)
4682 KASSERT(bo != NULL, ("NULL bo in bufobj_wdrop"));
4684 KASSERT(bo->bo_numoutput > 0, ("bufobj_wdrop non-positive count"));
4685 if ((--bo->bo_numoutput == 0) && (bo->bo_flag & BO_WWAIT)) {
4686 bo->bo_flag &= ~BO_WWAIT;
4687 wakeup(&bo->bo_numoutput);
4693 bufobj_wwait(struct bufobj *bo, int slpflag, int timeo)
4697 KASSERT(bo != NULL, ("NULL bo in bufobj_wwait"));
4698 ASSERT_BO_WLOCKED(bo);
4700 while (bo->bo_numoutput) {
4701 bo->bo_flag |= BO_WWAIT;
4702 error = msleep(&bo->bo_numoutput, BO_LOCKPTR(bo),
4703 slpflag | (PRIBIO + 1), "bo_wwait", timeo);
4711 * Set bio_data or bio_ma for struct bio from the struct buf.
4714 bdata2bio(struct buf *bp, struct bio *bip)
4717 if (!buf_mapped(bp)) {
4718 KASSERT(unmapped_buf_allowed, ("unmapped"));
4719 bip->bio_ma = bp->b_pages;
4720 bip->bio_ma_n = bp->b_npages;
4721 bip->bio_data = unmapped_buf;
4722 bip->bio_ma_offset = (vm_offset_t)bp->b_offset & PAGE_MASK;
4723 bip->bio_flags |= BIO_UNMAPPED;
4724 KASSERT(round_page(bip->bio_ma_offset + bip->bio_length) /
4725 PAGE_SIZE == bp->b_npages,
4726 ("Buffer %p too short: %d %lld %d", bp, bip->bio_ma_offset,
4727 (long long)bip->bio_length, bip->bio_ma_n));
4729 bip->bio_data = bp->b_data;
4735 * The MIPS pmap code currently doesn't handle aliased pages.
4736 * The VIPT caches may not handle page aliasing themselves, leading
4737 * to data corruption.
4739 * As such, this code makes a system extremely unhappy if said
4740 * system doesn't support unaliasing the above situation in hardware.
4741 * Some "recent" systems (eg some mips24k/mips74k cores) don't enable
4742 * this feature at build time, so it has to be handled in software.
4744 * Once the MIPS pmap/cache code grows to support this function on
4745 * earlier chips, it should be flipped back off.
4748 static int buf_pager_relbuf = 1;
4750 static int buf_pager_relbuf = 0;
4752 SYSCTL_INT(_vfs, OID_AUTO, buf_pager_relbuf, CTLFLAG_RWTUN,
4753 &buf_pager_relbuf, 0,
4754 "Make buffer pager release buffers after reading");
4757 * The buffer pager. It uses buffer reads to validate pages.
4759 * In contrast to the generic local pager from vm/vnode_pager.c, this
4760 * pager correctly and easily handles volumes where the underlying
4761 * device block size is greater than the machine page size. The
4762 * buffer cache transparently extends the requested page run to be
4763 * aligned at the block boundary, and does the necessary bogus page
4764 * replacements in the addends to avoid obliterating already valid
4767 * The only non-trivial issue is that the exclusive busy state for
4768 * pages, which is assumed by the vm_pager_getpages() interface, is
4769 * incompatible with the VMIO buffer cache's desire to share-busy the
4770 * pages. This function performs a trivial downgrade of the pages'
4771 * state before reading buffers, and a less trivial upgrade from the
4772 * shared-busy to excl-busy state after the read.
4775 vfs_bio_getpages(struct vnode *vp, vm_page_t *ma, int count,
4776 int *rbehind, int *rahead, vbg_get_lblkno_t get_lblkno,
4777 vbg_get_blksize_t get_blksize)
4784 vm_ooffset_t la, lb, poff, poffe;
4786 int bo_bs, br_flags, error, i, pgsin, pgsin_a, pgsin_b;
4789 object = vp->v_object;
4791 la = IDX_TO_OFF(ma[count - 1]->pindex);
4792 if (la >= object->un_pager.vnp.vnp_size)
4793 return (VM_PAGER_BAD);
4794 lpart = la + PAGE_SIZE > object->un_pager.vnp.vnp_size;
4795 bo_bs = get_blksize(vp, get_lblkno(vp, IDX_TO_OFF(ma[0]->pindex)));
4798 * Calculate read-ahead, behind and total pages.
4801 lb = IDX_TO_OFF(ma[0]->pindex);
4802 pgsin_b = OFF_TO_IDX(lb - rounddown2(lb, bo_bs));
4804 if (rbehind != NULL)
4806 pgsin_a = OFF_TO_IDX(roundup2(la, bo_bs) - la);
4807 if (la + IDX_TO_OFF(pgsin_a) >= object->un_pager.vnp.vnp_size)
4808 pgsin_a = OFF_TO_IDX(roundup2(object->un_pager.vnp.vnp_size,
4813 VM_CNT_INC(v_vnodein);
4814 VM_CNT_ADD(v_vnodepgsin, pgsin);
4816 br_flags = (mp != NULL && (mp->mnt_kern_flag & MNTK_UNMAPPED_BUFS)
4817 != 0) ? GB_UNMAPPED : 0;
4818 VM_OBJECT_WLOCK(object);
4820 for (i = 0; i < count; i++)
4821 vm_page_busy_downgrade(ma[i]);
4822 VM_OBJECT_WUNLOCK(object);
4825 for (i = 0; i < count; i++) {
4829 * Pages are shared busy and the object lock is not
4830 * owned, which together allow for the pages'
4831 * invalidation. The racy test for validity avoids
4832 * useless creation of the buffer for the most typical
4833 * case when invalidation is not used in redo or for
4834 * parallel read. The shared->excl upgrade loop at
4835 * the end of the function catches the race in a
4836 * reliable way (protected by the object lock).
4838 if (m->valid == VM_PAGE_BITS_ALL)
4841 poff = IDX_TO_OFF(m->pindex);
4842 poffe = MIN(poff + PAGE_SIZE, object->un_pager.vnp.vnp_size);
4843 for (; poff < poffe; poff += bsize) {
4844 lbn = get_lblkno(vp, poff);
4849 bsize = get_blksize(vp, lbn);
4850 error = bread_gb(vp, lbn, bsize, curthread->td_ucred,
4854 if (LIST_EMPTY(&bp->b_dep)) {
4856 * Invalidation clears m->valid, but
4857 * may leave B_CACHE flag if the
4858 * buffer existed at the invalidation
4859 * time. In this case, recycle the
4860 * buffer to do real read on next
4861 * bread() after redo.
4863 * Otherwise B_RELBUF is not strictly
4864 * necessary, enable to reduce buf
4867 if (buf_pager_relbuf ||
4868 m->valid != VM_PAGE_BITS_ALL)
4869 bp->b_flags |= B_RELBUF;
4871 bp->b_flags &= ~B_NOCACHE;
4877 KASSERT(1 /* racy, enable for debugging */ ||
4878 m->valid == VM_PAGE_BITS_ALL || i == count - 1,
4879 ("buf %d %p invalid", i, m));
4880 if (i == count - 1 && lpart) {
4881 VM_OBJECT_WLOCK(object);
4882 if (m->valid != 0 &&
4883 m->valid != VM_PAGE_BITS_ALL)
4884 vm_page_zero_invalid(m, TRUE);
4885 VM_OBJECT_WUNLOCK(object);
4891 VM_OBJECT_WLOCK(object);
4893 for (i = 0; i < count; i++) {
4894 vm_page_sunbusy(ma[i]);
4895 ma[i] = vm_page_grab(object, ma[i]->pindex, VM_ALLOC_NORMAL);
4898 * Since the pages were only sbusy while neither the
4899 * buffer nor the object lock was held by us, or
4900 * reallocated while vm_page_grab() slept for busy
4901 * relinguish, they could have been invalidated.
4902 * Recheck the valid bits and re-read as needed.
4904 * Note that the last page is made fully valid in the
4905 * read loop, and partial validity for the page at
4906 * index count - 1 could mean that the page was
4907 * invalidated or removed, so we must restart for
4910 if (ma[i]->valid != VM_PAGE_BITS_ALL)
4913 if (redo && error == 0)
4915 VM_OBJECT_WUNLOCK(object);
4916 return (error != 0 ? VM_PAGER_ERROR : VM_PAGER_OK);
4919 #include "opt_ddb.h"
4921 #include <ddb/ddb.h>
4923 /* DDB command to show buffer data */
4924 DB_SHOW_COMMAND(buffer, db_show_buffer)
4927 struct buf *bp = (struct buf *)addr;
4928 #ifdef FULL_BUF_TRACKING
4933 db_printf("usage: show buffer <addr>\n");
4937 db_printf("buf at %p\n", bp);
4938 db_printf("b_flags = 0x%b, b_xflags=0x%b, b_vflags=0x%b\n",
4939 (u_int)bp->b_flags, PRINT_BUF_FLAGS, (u_int)bp->b_xflags,
4940 PRINT_BUF_XFLAGS, (u_int)bp->b_vflags, PRINT_BUF_VFLAGS);
4942 "b_error = %d, b_bufsize = %ld, b_bcount = %ld, b_resid = %ld\n"
4943 "b_bufobj = (%p), b_data = %p, b_blkno = %jd, b_lblkno = %jd, "
4945 bp->b_error, bp->b_bufsize, bp->b_bcount, bp->b_resid,
4946 bp->b_bufobj, bp->b_data, (intmax_t)bp->b_blkno,
4947 (intmax_t)bp->b_lblkno, bp->b_dep.lh_first);
4948 db_printf("b_kvabase = %p, b_kvasize = %d\n",
4949 bp->b_kvabase, bp->b_kvasize);
4952 db_printf("b_npages = %d, pages(OBJ, IDX, PA): ", bp->b_npages);
4953 for (i = 0; i < bp->b_npages; i++) {
4957 db_printf("(%p, 0x%lx, 0x%lx)", m->object,
4959 (u_long)VM_PAGE_TO_PHYS(m));
4961 db_printf("( ??? )");
4962 if ((i + 1) < bp->b_npages)
4967 #if defined(FULL_BUF_TRACKING)
4968 db_printf("b_io_tracking: b_io_tcnt = %u\n", bp->b_io_tcnt);
4970 i = bp->b_io_tcnt % BUF_TRACKING_SIZE;
4971 for (j = 1; j <= BUF_TRACKING_SIZE; j++) {
4972 if (bp->b_io_tracking[BUF_TRACKING_ENTRY(i - j)] == NULL)
4974 db_printf(" %2u: %s\n", j,
4975 bp->b_io_tracking[BUF_TRACKING_ENTRY(i - j)]);
4977 #elif defined(BUF_TRACKING)
4978 db_printf("b_io_tracking: %s\n", bp->b_io_tracking);
4981 BUF_LOCKPRINTINFO(bp);
4984 DB_SHOW_COMMAND(lockedbufs, lockedbufs)
4989 for (i = 0; i < nbuf; i++) {
4991 if (BUF_ISLOCKED(bp)) {
4992 db_show_buffer((uintptr_t)bp, 1, 0, NULL);
5000 DB_SHOW_COMMAND(vnodebufs, db_show_vnodebufs)
5006 db_printf("usage: show vnodebufs <addr>\n");
5009 vp = (struct vnode *)addr;
5010 db_printf("Clean buffers:\n");
5011 TAILQ_FOREACH(bp, &vp->v_bufobj.bo_clean.bv_hd, b_bobufs) {
5012 db_show_buffer((uintptr_t)bp, 1, 0, NULL);
5015 db_printf("Dirty buffers:\n");
5016 TAILQ_FOREACH(bp, &vp->v_bufobj.bo_dirty.bv_hd, b_bobufs) {
5017 db_show_buffer((uintptr_t)bp, 1, 0, NULL);
5022 DB_COMMAND(countfreebufs, db_coundfreebufs)
5025 int i, used = 0, nfree = 0;
5028 db_printf("usage: countfreebufs\n");
5032 for (i = 0; i < nbuf; i++) {
5034 if (bp->b_qindex == QUEUE_EMPTY)
5040 db_printf("Counted %d free, %d used (%d tot)\n", nfree, used,
5042 db_printf("numfreebuffers is %d\n", numfreebuffers);