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_pageout.h>
79 #include <vm/vm_page.h>
80 #include <vm/vm_object.h>
81 #include <vm/vm_extern.h>
82 #include <vm/vm_map.h>
83 #include <vm/swap_pager.h>
84 #include "opt_compat.h"
87 static MALLOC_DEFINE(M_BIOBUF, "biobuf", "BIO buffer");
89 struct bio_ops bioops; /* I/O operation notification */
91 struct buf_ops buf_ops_bio = {
92 .bop_name = "buf_ops_bio",
93 .bop_write = bufwrite,
94 .bop_strategy = bufstrategy,
96 .bop_bdflush = bufbdflush,
99 static struct buf *buf; /* buffer header pool */
100 extern struct buf *swbuf; /* Swap buffer header pool. */
101 caddr_t unmapped_buf;
103 /* Used below and for softdep flushing threads in ufs/ffs/ffs_softdep.c */
104 struct proc *bufdaemonproc;
105 struct proc *bufspacedaemonproc;
107 static int inmem(struct vnode *vp, daddr_t blkno);
108 static void vm_hold_free_pages(struct buf *bp, int newbsize);
109 static void vm_hold_load_pages(struct buf *bp, vm_offset_t from,
111 static void vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, vm_page_t m);
112 static void vfs_page_set_validclean(struct buf *bp, vm_ooffset_t off,
114 static void vfs_clean_pages_dirty_buf(struct buf *bp);
115 static void vfs_setdirty_locked_object(struct buf *bp);
116 static void vfs_vmio_invalidate(struct buf *bp);
117 static void vfs_vmio_truncate(struct buf *bp, int npages);
118 static void vfs_vmio_extend(struct buf *bp, int npages, int size);
119 static int vfs_bio_clcheck(struct vnode *vp, int size,
120 daddr_t lblkno, daddr_t blkno);
121 static int buf_flush(struct vnode *vp, int);
122 static int buf_recycle(bool);
123 static int buf_scan(bool);
124 static int flushbufqueues(struct vnode *, int, int);
125 static void buf_daemon(void);
126 static void bremfreel(struct buf *bp);
127 static __inline void bd_wakeup(void);
128 static int sysctl_runningspace(SYSCTL_HANDLER_ARGS);
129 static void bufkva_reclaim(vmem_t *, int);
130 static void bufkva_free(struct buf *);
131 static int buf_import(void *, void **, int, int);
132 static void buf_release(void *, void **, int);
134 #if defined(COMPAT_FREEBSD4) || defined(COMPAT_FREEBSD5) || \
135 defined(COMPAT_FREEBSD6) || defined(COMPAT_FREEBSD7)
136 static int sysctl_bufspace(SYSCTL_HANDLER_ARGS);
139 int vmiodirenable = TRUE;
140 SYSCTL_INT(_vfs, OID_AUTO, vmiodirenable, CTLFLAG_RW, &vmiodirenable, 0,
141 "Use the VM system for directory writes");
142 long runningbufspace;
143 SYSCTL_LONG(_vfs, OID_AUTO, runningbufspace, CTLFLAG_RD, &runningbufspace, 0,
144 "Amount of presently outstanding async buffer io");
145 static long bufspace;
146 #if defined(COMPAT_FREEBSD4) || defined(COMPAT_FREEBSD5) || \
147 defined(COMPAT_FREEBSD6) || defined(COMPAT_FREEBSD7)
148 SYSCTL_PROC(_vfs, OID_AUTO, bufspace, CTLTYPE_LONG|CTLFLAG_MPSAFE|CTLFLAG_RD,
149 &bufspace, 0, sysctl_bufspace, "L", "Virtual memory used for buffers");
151 SYSCTL_LONG(_vfs, OID_AUTO, bufspace, CTLFLAG_RD, &bufspace, 0,
152 "Physical memory used for buffers");
154 static long bufkvaspace;
155 SYSCTL_LONG(_vfs, OID_AUTO, bufkvaspace, CTLFLAG_RD, &bufkvaspace, 0,
156 "Kernel virtual memory used for buffers");
157 static long maxbufspace;
158 SYSCTL_LONG(_vfs, OID_AUTO, maxbufspace, CTLFLAG_RW, &maxbufspace, 0,
159 "Maximum allowed value of bufspace (including metadata)");
160 static long bufmallocspace;
161 SYSCTL_LONG(_vfs, OID_AUTO, bufmallocspace, CTLFLAG_RD, &bufmallocspace, 0,
162 "Amount of malloced memory for buffers");
163 static long maxbufmallocspace;
164 SYSCTL_LONG(_vfs, OID_AUTO, maxmallocbufspace, CTLFLAG_RW, &maxbufmallocspace,
165 0, "Maximum amount of malloced memory for buffers");
166 static long lobufspace;
167 SYSCTL_LONG(_vfs, OID_AUTO, lobufspace, CTLFLAG_RW, &lobufspace, 0,
168 "Minimum amount of buffers we want to have");
170 SYSCTL_LONG(_vfs, OID_AUTO, hibufspace, CTLFLAG_RW, &hibufspace, 0,
171 "Maximum allowed value of bufspace (excluding metadata)");
173 SYSCTL_LONG(_vfs, OID_AUTO, bufspacethresh, CTLFLAG_RW, &bufspacethresh,
174 0, "Bufspace consumed before waking the daemon to free some");
175 static int buffreekvacnt;
176 SYSCTL_INT(_vfs, OID_AUTO, buffreekvacnt, CTLFLAG_RW, &buffreekvacnt, 0,
177 "Number of times we have freed the KVA space from some buffer");
178 static int bufdefragcnt;
179 SYSCTL_INT(_vfs, OID_AUTO, bufdefragcnt, CTLFLAG_RW, &bufdefragcnt, 0,
180 "Number of times we have had to repeat buffer allocation to defragment");
181 static long lorunningspace;
182 SYSCTL_PROC(_vfs, OID_AUTO, lorunningspace, CTLTYPE_LONG | CTLFLAG_MPSAFE |
183 CTLFLAG_RW, &lorunningspace, 0, sysctl_runningspace, "L",
184 "Minimum preferred space used for in-progress I/O");
185 static long hirunningspace;
186 SYSCTL_PROC(_vfs, OID_AUTO, hirunningspace, CTLTYPE_LONG | CTLFLAG_MPSAFE |
187 CTLFLAG_RW, &hirunningspace, 0, sysctl_runningspace, "L",
188 "Maximum amount of space to use for in-progress I/O");
189 int dirtybufferflushes;
190 SYSCTL_INT(_vfs, OID_AUTO, dirtybufferflushes, CTLFLAG_RW, &dirtybufferflushes,
191 0, "Number of bdwrite to bawrite conversions to limit dirty buffers");
193 SYSCTL_INT(_vfs, OID_AUTO, bdwriteskip, CTLFLAG_RW, &bdwriteskip,
194 0, "Number of buffers supplied to bdwrite with snapshot deadlock risk");
195 int altbufferflushes;
196 SYSCTL_INT(_vfs, OID_AUTO, altbufferflushes, CTLFLAG_RW, &altbufferflushes,
197 0, "Number of fsync flushes to limit dirty buffers");
198 static int recursiveflushes;
199 SYSCTL_INT(_vfs, OID_AUTO, recursiveflushes, CTLFLAG_RW, &recursiveflushes,
200 0, "Number of flushes skipped due to being recursive");
201 static int numdirtybuffers;
202 SYSCTL_INT(_vfs, OID_AUTO, numdirtybuffers, CTLFLAG_RD, &numdirtybuffers, 0,
203 "Number of buffers that are dirty (has unwritten changes) at the moment");
204 static int lodirtybuffers;
205 SYSCTL_INT(_vfs, OID_AUTO, lodirtybuffers, CTLFLAG_RW, &lodirtybuffers, 0,
206 "How many buffers we want to have free before bufdaemon can sleep");
207 static int hidirtybuffers;
208 SYSCTL_INT(_vfs, OID_AUTO, hidirtybuffers, CTLFLAG_RW, &hidirtybuffers, 0,
209 "When the number of dirty buffers is considered severe");
211 SYSCTL_INT(_vfs, OID_AUTO, dirtybufthresh, CTLFLAG_RW, &dirtybufthresh,
212 0, "Number of bdwrite to bawrite conversions to clear dirty buffers");
213 static int numfreebuffers;
214 SYSCTL_INT(_vfs, OID_AUTO, numfreebuffers, CTLFLAG_RD, &numfreebuffers, 0,
215 "Number of free buffers");
216 static int lofreebuffers;
217 SYSCTL_INT(_vfs, OID_AUTO, lofreebuffers, CTLFLAG_RW, &lofreebuffers, 0,
218 "Target number of free buffers");
219 static int hifreebuffers;
220 SYSCTL_INT(_vfs, OID_AUTO, hifreebuffers, CTLFLAG_RW, &hifreebuffers, 0,
221 "Threshold for clean buffer recycling");
222 static int getnewbufcalls;
223 SYSCTL_INT(_vfs, OID_AUTO, getnewbufcalls, CTLFLAG_RW, &getnewbufcalls, 0,
224 "Number of calls to getnewbuf");
225 static int getnewbufrestarts;
226 SYSCTL_INT(_vfs, OID_AUTO, getnewbufrestarts, CTLFLAG_RW, &getnewbufrestarts, 0,
227 "Number of times getnewbuf has had to restart a buffer acquisition");
228 static int mappingrestarts;
229 SYSCTL_INT(_vfs, OID_AUTO, mappingrestarts, CTLFLAG_RW, &mappingrestarts, 0,
230 "Number of times getblk has had to restart a buffer mapping for "
232 static int numbufallocfails;
233 SYSCTL_INT(_vfs, OID_AUTO, numbufallocfails, CTLFLAG_RW, &numbufallocfails, 0,
234 "Number of times buffer allocations failed");
235 static int flushbufqtarget = 100;
236 SYSCTL_INT(_vfs, OID_AUTO, flushbufqtarget, CTLFLAG_RW, &flushbufqtarget, 0,
237 "Amount of work to do in flushbufqueues when helping bufdaemon");
238 static long notbufdflushes;
239 SYSCTL_LONG(_vfs, OID_AUTO, notbufdflushes, CTLFLAG_RD, ¬bufdflushes, 0,
240 "Number of dirty buffer flushes done by the bufdaemon helpers");
241 static long barrierwrites;
242 SYSCTL_LONG(_vfs, OID_AUTO, barrierwrites, CTLFLAG_RW, &barrierwrites, 0,
243 "Number of barrier writes");
244 SYSCTL_INT(_vfs, OID_AUTO, unmapped_buf_allowed, CTLFLAG_RD,
245 &unmapped_buf_allowed, 0,
246 "Permit the use of the unmapped i/o");
249 * This lock synchronizes access to bd_request.
251 static struct mtx_padalign bdlock;
254 * This lock protects the runningbufreq and synchronizes runningbufwakeup and
255 * waitrunningbufspace().
257 static struct mtx_padalign rbreqlock;
260 * Lock that protects needsbuffer and the sleeps/wakeups surrounding it.
262 static struct rwlock_padalign nblock;
265 * Lock that protects bdirtywait.
267 static struct mtx_padalign bdirtylock;
270 * Wakeup point for bufdaemon, as well as indicator of whether it is already
271 * active. Set to 1 when the bufdaemon is already "on" the queue, 0 when it
274 static int bd_request;
277 * Request/wakeup point for the bufspace daemon.
279 static int bufspace_request;
282 * Request for the buf daemon to write more buffers than is indicated by
283 * lodirtybuf. This may be necessary to push out excess dependencies or
284 * defragment the address space where a simple count of the number of dirty
285 * buffers is insufficient to characterize the demand for flushing them.
287 static int bd_speedupreq;
290 * bogus page -- for I/O to/from partially complete buffers
291 * this is a temporary solution to the problem, but it is not
292 * really that bad. it would be better to split the buffer
293 * for input in the case of buffers partially already in memory,
294 * but the code is intricate enough already.
296 vm_page_t bogus_page;
299 * Synchronization (sleep/wakeup) variable for active buffer space requests.
300 * Set when wait starts, cleared prior to wakeup().
301 * Used in runningbufwakeup() and waitrunningbufspace().
303 static int runningbufreq;
306 * Synchronization (sleep/wakeup) variable for buffer requests.
307 * Can contain the VFS_BIO_NEED flags defined below; setting/clearing is done
309 * Used in numdirtywakeup(), bufspace_wakeup(), bwillwrite(),
310 * getnewbuf(), and getblk().
312 static volatile int needsbuffer;
315 * Synchronization for bwillwrite() waiters.
317 static int bdirtywait;
320 * Definitions for the buffer free lists.
322 #define QUEUE_NONE 0 /* on no queue */
323 #define QUEUE_EMPTY 1 /* empty buffer headers */
324 #define QUEUE_DIRTY 2 /* B_DELWRI buffers */
325 #define QUEUE_CLEAN 3 /* non-B_DELWRI buffers */
326 #define QUEUE_SENTINEL 1024 /* not an queue index, but mark for sentinel */
328 /* Maximum number of clean buffer queues. */
329 #define CLEAN_QUEUES 16
331 /* Configured number of clean queues. */
332 static int clean_queues;
334 /* Maximum number of buffer queues. */
335 #define BUFFER_QUEUES (QUEUE_CLEAN + CLEAN_QUEUES)
337 /* Queues for free buffers with various properties */
338 static TAILQ_HEAD(bqueues, buf) bufqueues[BUFFER_QUEUES] = { { 0 } };
340 static int bq_len[BUFFER_QUEUES];
344 * Lock for each bufqueue
346 static struct mtx_padalign bqlocks[BUFFER_QUEUES];
349 * per-cpu empty buffer cache.
354 * Single global constant for BUF_WMESG, to avoid getting multiple references.
355 * buf_wmesg is referred from macros.
357 const char *buf_wmesg = BUF_WMESG;
360 sysctl_runningspace(SYSCTL_HANDLER_ARGS)
365 value = *(long *)arg1;
366 error = sysctl_handle_long(oidp, &value, 0, req);
367 if (error != 0 || req->newptr == NULL)
369 mtx_lock(&rbreqlock);
370 if (arg1 == &hirunningspace) {
371 if (value < lorunningspace)
374 hirunningspace = value;
376 KASSERT(arg1 == &lorunningspace,
377 ("%s: unknown arg1", __func__));
378 if (value > hirunningspace)
381 lorunningspace = value;
383 mtx_unlock(&rbreqlock);
387 #if defined(COMPAT_FREEBSD4) || defined(COMPAT_FREEBSD5) || \
388 defined(COMPAT_FREEBSD6) || defined(COMPAT_FREEBSD7)
390 sysctl_bufspace(SYSCTL_HANDLER_ARGS)
395 if (sizeof(int) == sizeof(long) || req->oldlen >= sizeof(long))
396 return (sysctl_handle_long(oidp, arg1, arg2, req));
397 lvalue = *(long *)arg1;
398 if (lvalue > INT_MAX)
399 /* On overflow, still write out a long to trigger ENOMEM. */
400 return (sysctl_handle_long(oidp, &lvalue, 0, req));
402 return (sysctl_handle_int(oidp, &ivalue, 0, req));
411 return ((atomic_fetchadd_int(&nextq, 1) % clean_queues) + QUEUE_CLEAN);
415 bqisclean(int qindex)
418 return (qindex >= QUEUE_CLEAN && qindex < QUEUE_CLEAN + CLEAN_QUEUES);
424 * Return the appropriate queue lock based on the index.
426 static inline struct mtx *
430 return (struct mtx *)&bqlocks[qindex];
436 * Wakeup any bwillwrite() waiters.
441 mtx_lock(&bdirtylock);
446 mtx_unlock(&bdirtylock);
452 * Decrement the numdirtybuffers count by one and wakeup any
453 * threads blocked in bwillwrite().
459 if (atomic_fetchadd_int(&numdirtybuffers, -1) ==
460 (lodirtybuffers + hidirtybuffers) / 2)
467 * Increment the numdirtybuffers count by one and wakeup the buf
475 * Only do the wakeup once as we cross the boundary. The
476 * buf daemon will keep running until the condition clears.
478 if (atomic_fetchadd_int(&numdirtybuffers, 1) ==
479 (lodirtybuffers + hidirtybuffers) / 2)
486 * Called when buffer space is potentially available for recovery.
487 * getnewbuf() will block on this flag when it is unable to free
488 * sufficient buffer space. Buffer space becomes recoverable when
489 * bp's get placed back in the queues.
492 bufspace_wakeup(void)
496 * If someone is waiting for bufspace, wake them up.
498 * Since needsbuffer is set prior to doing an additional queue
499 * scan it is safe to check for the flag prior to acquiring the
500 * lock. The thread that is preparing to scan again before
501 * blocking would discover the buf we released.
505 if (atomic_cmpset_int(&needsbuffer, 1, 0) == 1)
506 wakeup(__DEVOLATILE(void *, &needsbuffer));
512 * bufspace_daemonwakeup:
514 * Wakeup the daemon responsible for freeing clean bufs.
517 bufspace_daemonwakeup(void)
520 if (bufspace_request == 0) {
521 bufspace_request = 1;
522 wakeup(&bufspace_request);
530 * Adjust the reported bufspace for a KVA managed buffer, possibly
531 * waking any waiters.
534 bufspace_adjust(struct buf *bp, int bufsize)
539 KASSERT((bp->b_flags & B_MALLOC) == 0,
540 ("bufspace_adjust: malloc buf %p", bp));
541 diff = bufsize - bp->b_bufsize;
543 atomic_subtract_long(&bufspace, -diff);
546 space = atomic_fetchadd_long(&bufspace, diff);
547 /* Wake up the daemon on the transition. */
548 if (space < bufspacethresh && space + diff >= bufspacethresh)
549 bufspace_daemonwakeup();
551 bp->b_bufsize = bufsize;
557 * Reserve bufspace before calling allocbuf(). metadata has a
558 * different space limit than data.
561 bufspace_reserve(int size, bool metadata)
572 if (space + size > limit)
574 } while (atomic_cmpset_long(&bufspace, space, space + size) == 0);
576 /* Wake up the daemon on the transition. */
577 if (space < bufspacethresh && space + size >= bufspacethresh)
578 bufspace_daemonwakeup();
586 * Release reserved bufspace after bufspace_adjust() has consumed it.
589 bufspace_release(int size)
591 atomic_subtract_long(&bufspace, size);
598 * Wait for bufspace, acting as the buf daemon if a locked vnode is
599 * supplied. needsbuffer must be set in a safe fashion prior to
600 * polling for space. The operation must be re-tried on return.
603 bufspace_wait(struct vnode *vp, int gbflags, int slpflag, int slptimeo)
606 int error, fl, norunbuf;
608 if ((gbflags & GB_NOWAIT_BD) != 0)
613 while (needsbuffer != 0) {
614 if (vp != NULL && vp->v_type != VCHR &&
615 (td->td_pflags & TDP_BUFNEED) == 0) {
618 * getblk() is called with a vnode locked, and
619 * some majority of the dirty buffers may as
620 * well belong to the vnode. Flushing the
621 * buffers there would make a progress that
622 * cannot be achieved by the buf_daemon, that
623 * cannot lock the vnode.
625 norunbuf = ~(TDP_BUFNEED | TDP_NORUNNINGBUF) |
626 (td->td_pflags & TDP_NORUNNINGBUF);
629 * Play bufdaemon. The getnewbuf() function
630 * may be called while the thread owns lock
631 * for another dirty buffer for the same
632 * vnode, which makes it impossible to use
633 * VOP_FSYNC() there, due to the buffer lock
636 td->td_pflags |= TDP_BUFNEED | TDP_NORUNNINGBUF;
637 fl = buf_flush(vp, flushbufqtarget);
638 td->td_pflags &= norunbuf;
642 if (needsbuffer == 0)
645 error = rw_sleep(__DEVOLATILE(void *, &needsbuffer), &nblock,
646 (PRIBIO + 4) | slpflag, "newbuf", slptimeo);
657 * buffer space management daemon. Tries to maintain some marginal
658 * amount of free buffer space so that requesting processes neither
659 * block nor work to reclaim buffers.
662 bufspace_daemon(void)
665 kproc_suspend_check(bufspacedaemonproc);
668 * Free buffers from the clean queue until we meet our
671 * Theory of operation: The buffer cache is most efficient
672 * when some free buffer headers and space are always
673 * available to getnewbuf(). This daemon attempts to prevent
674 * the excessive blocking and synchronization associated
675 * with shortfall. It goes through three phases according
678 * 1) The daemon wakes up voluntarily once per-second
679 * during idle periods when the counters are below
680 * the wakeup thresholds (bufspacethresh, lofreebuffers).
682 * 2) The daemon wakes up as we cross the thresholds
683 * ahead of any potential blocking. This may bounce
684 * slightly according to the rate of consumption and
687 * 3) The daemon and consumers are starved for working
688 * clean buffers. This is the 'bufspace' sleep below
689 * which will inefficiently trade bufs with bqrelse
690 * until we return to condition 2.
692 while (bufspace > lobufspace ||
693 numfreebuffers < hifreebuffers) {
694 if (buf_recycle(false) != 0) {
695 atomic_set_int(&needsbuffer, 1);
696 if (buf_recycle(false) != 0) {
699 rw_sleep(__DEVOLATILE(void *,
700 &needsbuffer), &nblock,
701 PRIBIO|PDROP, "bufspace",
711 * Re-check our limits under the exclusive nblock.
714 if (bufspace < bufspacethresh &&
715 numfreebuffers > lofreebuffers) {
716 bufspace_request = 0;
717 rw_sleep(&bufspace_request, &nblock, PRIBIO|PDROP,
724 static struct kproc_desc bufspace_kp = {
729 SYSINIT(bufspacedaemon, SI_SUB_KTHREAD_BUF, SI_ORDER_FIRST, kproc_start,
735 * Adjust the reported bufspace for a malloc managed buffer, possibly
736 * waking any waiters.
739 bufmallocadjust(struct buf *bp, int bufsize)
743 KASSERT((bp->b_flags & B_MALLOC) != 0,
744 ("bufmallocadjust: non-malloc buf %p", bp));
745 diff = bufsize - bp->b_bufsize;
747 atomic_subtract_long(&bufmallocspace, -diff);
749 atomic_add_long(&bufmallocspace, diff);
750 bp->b_bufsize = bufsize;
756 * Wake up processes that are waiting on asynchronous writes to fall
757 * below lorunningspace.
763 mtx_lock(&rbreqlock);
766 wakeup(&runningbufreq);
768 mtx_unlock(&rbreqlock);
774 * Decrement the outstanding write count according.
777 runningbufwakeup(struct buf *bp)
781 bspace = bp->b_runningbufspace;
784 space = atomic_fetchadd_long(&runningbufspace, -bspace);
785 KASSERT(space >= bspace, ("runningbufspace underflow %ld %ld",
787 bp->b_runningbufspace = 0;
789 * Only acquire the lock and wakeup on the transition from exceeding
790 * the threshold to falling below it.
792 if (space < lorunningspace)
794 if (space - bspace > lorunningspace)
800 * waitrunningbufspace()
802 * runningbufspace is a measure of the amount of I/O currently
803 * running. This routine is used in async-write situations to
804 * prevent creating huge backups of pending writes to a device.
805 * Only asynchronous writes are governed by this function.
807 * This does NOT turn an async write into a sync write. It waits
808 * for earlier writes to complete and generally returns before the
809 * caller's write has reached the device.
812 waitrunningbufspace(void)
815 mtx_lock(&rbreqlock);
816 while (runningbufspace > hirunningspace) {
818 msleep(&runningbufreq, &rbreqlock, PVM, "wdrain", 0);
820 mtx_unlock(&rbreqlock);
825 * vfs_buf_test_cache:
827 * Called when a buffer is extended. This function clears the B_CACHE
828 * bit if the newly extended portion of the buffer does not contain
832 vfs_buf_test_cache(struct buf *bp, vm_ooffset_t foff, vm_offset_t off,
833 vm_offset_t size, vm_page_t m)
836 VM_OBJECT_ASSERT_LOCKED(m->object);
837 if (bp->b_flags & B_CACHE) {
838 int base = (foff + off) & PAGE_MASK;
839 if (vm_page_is_valid(m, base, size) == 0)
840 bp->b_flags &= ~B_CACHE;
844 /* Wake up the buffer daemon if necessary */
850 if (bd_request == 0) {
858 * bd_speedup - speedup the buffer cache flushing code
867 if (bd_speedupreq == 0 || bd_request == 0)
877 #define NSWBUF_MIN 16
881 #define TRANSIENT_DENOM 5
883 #define TRANSIENT_DENOM 10
887 * Calculating buffer cache scaling values and reserve space for buffer
888 * headers. This is called during low level kernel initialization and
889 * may be called more then once. We CANNOT write to the memory area
890 * being reserved at this time.
893 kern_vfs_bio_buffer_alloc(caddr_t v, long physmem_est)
896 long maxbuf, maxbuf_sz, buf_sz, biotmap_sz;
899 * physmem_est is in pages. Convert it to kilobytes (assumes
900 * PAGE_SIZE is >= 1K)
902 physmem_est = physmem_est * (PAGE_SIZE / 1024);
905 * The nominal buffer size (and minimum KVA allocation) is BKVASIZE.
906 * For the first 64MB of ram nominally allocate sufficient buffers to
907 * cover 1/4 of our ram. Beyond the first 64MB allocate additional
908 * buffers to cover 1/10 of our ram over 64MB. When auto-sizing
909 * the buffer cache we limit the eventual kva reservation to
912 * factor represents the 1/4 x ram conversion.
915 int factor = 4 * BKVASIZE / 1024;
918 if (physmem_est > 4096)
919 nbuf += min((physmem_est - 4096) / factor,
921 if (physmem_est > 65536)
922 nbuf += min((physmem_est - 65536) * 2 / (factor * 5),
923 32 * 1024 * 1024 / (factor * 5));
925 if (maxbcache && nbuf > maxbcache / BKVASIZE)
926 nbuf = maxbcache / BKVASIZE;
931 /* XXX Avoid unsigned long overflows later on with maxbufspace. */
932 maxbuf = (LONG_MAX / 3) / BKVASIZE;
935 printf("Warning: nbufs lowered from %d to %ld\n", nbuf,
941 * Ideal allocation size for the transient bio submap is 10%
942 * of the maximal space buffer map. This roughly corresponds
943 * to the amount of the buffer mapped for typical UFS load.
945 * Clip the buffer map to reserve space for the transient
946 * BIOs, if its extent is bigger than 90% (80% on i386) of the
947 * maximum buffer map extent on the platform.
949 * The fall-back to the maxbuf in case of maxbcache unset,
950 * allows to not trim the buffer KVA for the architectures
951 * with ample KVA space.
953 if (bio_transient_maxcnt == 0 && unmapped_buf_allowed) {
954 maxbuf_sz = maxbcache != 0 ? maxbcache : maxbuf * BKVASIZE;
955 buf_sz = (long)nbuf * BKVASIZE;
956 if (buf_sz < maxbuf_sz / TRANSIENT_DENOM *
957 (TRANSIENT_DENOM - 1)) {
959 * There is more KVA than memory. Do not
960 * adjust buffer map size, and assign the rest
961 * of maxbuf to transient map.
963 biotmap_sz = maxbuf_sz - buf_sz;
966 * Buffer map spans all KVA we could afford on
967 * this platform. Give 10% (20% on i386) of
968 * the buffer map to the transient bio map.
970 biotmap_sz = buf_sz / TRANSIENT_DENOM;
971 buf_sz -= biotmap_sz;
973 if (biotmap_sz / INT_MAX > MAXPHYS)
974 bio_transient_maxcnt = INT_MAX;
976 bio_transient_maxcnt = biotmap_sz / MAXPHYS;
978 * Artificially limit to 1024 simultaneous in-flight I/Os
979 * using the transient mapping.
981 if (bio_transient_maxcnt > 1024)
982 bio_transient_maxcnt = 1024;
984 nbuf = buf_sz / BKVASIZE;
988 * swbufs are used as temporary holders for I/O, such as paging I/O.
989 * We have no less then 16 and no more then 256.
991 nswbuf = min(nbuf / 4, 256);
992 TUNABLE_INT_FETCH("kern.nswbuf", &nswbuf);
993 if (nswbuf < NSWBUF_MIN)
997 * Reserve space for the buffer cache buffers
1000 v = (caddr_t)(swbuf + nswbuf);
1002 v = (caddr_t)(buf + nbuf);
1007 /* Initialize the buffer subsystem. Called before use of any buffers. */
1014 CTASSERT(MAXBCACHEBUF >= MAXBSIZE);
1015 mtx_init(&bqlocks[QUEUE_DIRTY], "bufq dirty lock", NULL, MTX_DEF);
1016 mtx_init(&bqlocks[QUEUE_EMPTY], "bufq empty lock", NULL, MTX_DEF);
1017 for (i = QUEUE_CLEAN; i < QUEUE_CLEAN + CLEAN_QUEUES; i++)
1018 mtx_init(&bqlocks[i], "bufq clean lock", NULL, MTX_DEF);
1019 mtx_init(&rbreqlock, "runningbufspace lock", NULL, MTX_DEF);
1020 rw_init(&nblock, "needsbuffer lock");
1021 mtx_init(&bdlock, "buffer daemon lock", NULL, MTX_DEF);
1022 mtx_init(&bdirtylock, "dirty buf lock", NULL, MTX_DEF);
1024 /* next, make a null set of free lists */
1025 for (i = 0; i < BUFFER_QUEUES; i++)
1026 TAILQ_INIT(&bufqueues[i]);
1028 unmapped_buf = (caddr_t)kva_alloc(MAXPHYS);
1030 /* finally, initialize each buffer header and stick on empty q */
1031 for (i = 0; i < nbuf; i++) {
1033 bzero(bp, sizeof *bp);
1034 bp->b_flags = B_INVAL;
1035 bp->b_rcred = NOCRED;
1036 bp->b_wcred = NOCRED;
1037 bp->b_qindex = QUEUE_EMPTY;
1039 bp->b_data = bp->b_kvabase = unmapped_buf;
1040 LIST_INIT(&bp->b_dep);
1042 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_EMPTY], bp, b_freelist);
1044 bq_len[QUEUE_EMPTY]++;
1049 * maxbufspace is the absolute maximum amount of buffer space we are
1050 * allowed to reserve in KVM and in real terms. The absolute maximum
1051 * is nominally used by metadata. hibufspace is the nominal maximum
1052 * used by most other requests. The differential is required to
1053 * ensure that metadata deadlocks don't occur.
1055 * maxbufspace is based on BKVASIZE. Allocating buffers larger then
1056 * this may result in KVM fragmentation which is not handled optimally
1057 * by the system. XXX This is less true with vmem. We could use
1060 maxbufspace = (long)nbuf * BKVASIZE;
1061 hibufspace = lmax(3 * maxbufspace / 4, maxbufspace - MAXBCACHEBUF * 10);
1062 lobufspace = (hibufspace / 20) * 19; /* 95% */
1063 bufspacethresh = lobufspace + (hibufspace - lobufspace) / 2;
1066 * Note: The 16 MiB upper limit for hirunningspace was chosen
1067 * arbitrarily and may need further tuning. It corresponds to
1068 * 128 outstanding write IO requests (if IO size is 128 KiB),
1069 * which fits with many RAID controllers' tagged queuing limits.
1070 * The lower 1 MiB limit is the historical upper limit for
1073 hirunningspace = lmax(lmin(roundup(hibufspace / 64, MAXBCACHEBUF),
1074 16 * 1024 * 1024), 1024 * 1024);
1075 lorunningspace = roundup((hirunningspace * 2) / 3, MAXBCACHEBUF);
1078 * Limit the amount of malloc memory since it is wired permanently into
1079 * the kernel space. Even though this is accounted for in the buffer
1080 * allocation, we don't want the malloced region to grow uncontrolled.
1081 * The malloc scheme improves memory utilization significantly on
1082 * average (small) directories.
1084 maxbufmallocspace = hibufspace / 20;
1087 * Reduce the chance of a deadlock occurring by limiting the number
1088 * of delayed-write dirty buffers we allow to stack up.
1090 hidirtybuffers = nbuf / 4 + 20;
1091 dirtybufthresh = hidirtybuffers * 9 / 10;
1092 numdirtybuffers = 0;
1094 * To support extreme low-memory systems, make sure hidirtybuffers
1095 * cannot eat up all available buffer space. This occurs when our
1096 * minimum cannot be met. We try to size hidirtybuffers to 3/4 our
1097 * buffer space assuming BKVASIZE'd buffers.
1099 while ((long)hidirtybuffers * BKVASIZE > 3 * hibufspace / 4) {
1100 hidirtybuffers >>= 1;
1102 lodirtybuffers = hidirtybuffers / 2;
1105 * lofreebuffers should be sufficient to avoid stalling waiting on
1106 * buf headers under heavy utilization. The bufs in per-cpu caches
1107 * are counted as free but will be unavailable to threads executing
1110 * hifreebuffers is the free target for the bufspace daemon. This
1111 * should be set appropriately to limit work per-iteration.
1113 lofreebuffers = MIN((nbuf / 25) + (20 * mp_ncpus), 128 * mp_ncpus);
1114 hifreebuffers = (3 * lofreebuffers) / 2;
1115 numfreebuffers = nbuf;
1117 bogus_page = vm_page_alloc(NULL, 0, VM_ALLOC_NOOBJ |
1118 VM_ALLOC_NORMAL | VM_ALLOC_WIRED);
1120 /* Setup the kva and free list allocators. */
1121 vmem_set_reclaim(buffer_arena, bufkva_reclaim);
1122 buf_zone = uma_zcache_create("buf free cache", sizeof(struct buf),
1123 NULL, NULL, NULL, NULL, buf_import, buf_release, NULL, 0);
1126 * Size the clean queue according to the amount of buffer space.
1127 * One queue per-256mb up to the max. More queues gives better
1128 * concurrency but less accurate LRU.
1130 clean_queues = MIN(howmany(maxbufspace, 256*1024*1024), CLEAN_QUEUES);
1136 vfs_buf_check_mapped(struct buf *bp)
1139 KASSERT(bp->b_kvabase != unmapped_buf,
1140 ("mapped buf: b_kvabase was not updated %p", bp));
1141 KASSERT(bp->b_data != unmapped_buf,
1142 ("mapped buf: b_data was not updated %p", bp));
1143 KASSERT(bp->b_data < unmapped_buf || bp->b_data >= unmapped_buf +
1144 MAXPHYS, ("b_data + b_offset unmapped %p", bp));
1148 vfs_buf_check_unmapped(struct buf *bp)
1151 KASSERT(bp->b_data == unmapped_buf,
1152 ("unmapped buf: corrupted b_data %p", bp));
1155 #define BUF_CHECK_MAPPED(bp) vfs_buf_check_mapped(bp)
1156 #define BUF_CHECK_UNMAPPED(bp) vfs_buf_check_unmapped(bp)
1158 #define BUF_CHECK_MAPPED(bp) do {} while (0)
1159 #define BUF_CHECK_UNMAPPED(bp) do {} while (0)
1163 isbufbusy(struct buf *bp)
1165 if (((bp->b_flags & B_INVAL) == 0 && BUF_ISLOCKED(bp)) ||
1166 ((bp->b_flags & (B_DELWRI | B_INVAL)) == B_DELWRI))
1172 * Shutdown the system cleanly to prepare for reboot, halt, or power off.
1175 bufshutdown(int show_busybufs)
1177 static int first_buf_printf = 1;
1179 int iter, nbusy, pbusy;
1185 * Sync filesystems for shutdown
1187 wdog_kern_pat(WD_LASTVAL);
1188 sys_sync(curthread, NULL);
1191 * With soft updates, some buffers that are
1192 * written will be remarked as dirty until other
1193 * buffers are written.
1195 for (iter = pbusy = 0; iter < 20; iter++) {
1197 for (bp = &buf[nbuf]; --bp >= buf; )
1201 if (first_buf_printf)
1202 printf("All buffers synced.");
1205 if (first_buf_printf) {
1206 printf("Syncing disks, buffers remaining... ");
1207 first_buf_printf = 0;
1209 printf("%d ", nbusy);
1214 wdog_kern_pat(WD_LASTVAL);
1215 sys_sync(curthread, NULL);
1219 * Drop Giant and spin for a while to allow
1220 * interrupt threads to run.
1223 DELAY(50000 * iter);
1227 * Drop Giant and context switch several times to
1228 * allow interrupt threads to run.
1231 for (subiter = 0; subiter < 50 * iter; subiter++) {
1232 thread_lock(curthread);
1233 mi_switch(SW_VOL, NULL);
1234 thread_unlock(curthread);
1242 * Count only busy local buffers to prevent forcing
1243 * a fsck if we're just a client of a wedged NFS server
1246 for (bp = &buf[nbuf]; --bp >= buf; ) {
1247 if (isbufbusy(bp)) {
1249 /* XXX: This is bogus. We should probably have a BO_REMOTE flag instead */
1250 if (bp->b_dev == NULL) {
1251 TAILQ_REMOVE(&mountlist,
1252 bp->b_vp->v_mount, mnt_list);
1257 if (show_busybufs > 0) {
1259 "%d: buf:%p, vnode:%p, flags:%0x, blkno:%jd, lblkno:%jd, buflock:",
1260 nbusy, bp, bp->b_vp, bp->b_flags,
1261 (intmax_t)bp->b_blkno,
1262 (intmax_t)bp->b_lblkno);
1263 BUF_LOCKPRINTINFO(bp);
1264 if (show_busybufs > 1)
1272 * Failed to sync all blocks. Indicate this and don't
1273 * unmount filesystems (thus forcing an fsck on reboot).
1275 printf("Giving up on %d buffers\n", nbusy);
1276 DELAY(5000000); /* 5 seconds */
1278 if (!first_buf_printf)
1279 printf("Final sync complete\n");
1281 * Unmount filesystems
1283 if (panicstr == NULL)
1287 DELAY(100000); /* wait for console output to finish */
1291 bpmap_qenter(struct buf *bp)
1294 BUF_CHECK_MAPPED(bp);
1297 * bp->b_data is relative to bp->b_offset, but
1298 * bp->b_offset may be offset into the first page.
1300 bp->b_data = (caddr_t)trunc_page((vm_offset_t)bp->b_data);
1301 pmap_qenter((vm_offset_t)bp->b_data, bp->b_pages, bp->b_npages);
1302 bp->b_data = (caddr_t)((vm_offset_t)bp->b_data |
1303 (vm_offset_t)(bp->b_offset & PAGE_MASK));
1309 * Insert the buffer into the appropriate free list.
1312 binsfree(struct buf *bp, int qindex)
1314 struct mtx *olock, *nlock;
1316 if (qindex != QUEUE_EMPTY) {
1317 BUF_ASSERT_XLOCKED(bp);
1321 * Stick to the same clean queue for the lifetime of the buf to
1322 * limit locking below. Otherwise pick ont sequentially.
1324 if (qindex == QUEUE_CLEAN) {
1325 if (bqisclean(bp->b_qindex))
1326 qindex = bp->b_qindex;
1328 qindex = bqcleanq();
1332 * Handle delayed bremfree() processing.
1334 nlock = bqlock(qindex);
1335 if (bp->b_flags & B_REMFREE) {
1336 olock = bqlock(bp->b_qindex);
1339 if (olock != nlock) {
1346 if (bp->b_qindex != QUEUE_NONE)
1347 panic("binsfree: free buffer onto another queue???");
1349 bp->b_qindex = qindex;
1350 if (bp->b_flags & B_AGE)
1351 TAILQ_INSERT_HEAD(&bufqueues[bp->b_qindex], bp, b_freelist);
1353 TAILQ_INSERT_TAIL(&bufqueues[bp->b_qindex], bp, b_freelist);
1355 bq_len[bp->b_qindex]++;
1363 * Free a buffer to the buf zone once it no longer has valid contents.
1366 buf_free(struct buf *bp)
1369 if (bp->b_flags & B_REMFREE)
1371 if (bp->b_vflags & BV_BKGRDINPROG)
1372 panic("losing buffer 1");
1373 if (bp->b_rcred != NOCRED) {
1374 crfree(bp->b_rcred);
1375 bp->b_rcred = NOCRED;
1377 if (bp->b_wcred != NOCRED) {
1378 crfree(bp->b_wcred);
1379 bp->b_wcred = NOCRED;
1381 if (!LIST_EMPTY(&bp->b_dep))
1385 uma_zfree(buf_zone, bp);
1386 atomic_add_int(&numfreebuffers, 1);
1393 * Import bufs into the uma cache from the buf list. The system still
1394 * expects a static array of bufs and much of the synchronization
1395 * around bufs assumes type stable storage. As a result, UMA is used
1396 * only as a per-cpu cache of bufs still maintained on a global list.
1399 buf_import(void *arg, void **store, int cnt, int flags)
1404 mtx_lock(&bqlocks[QUEUE_EMPTY]);
1405 for (i = 0; i < cnt; i++) {
1406 bp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTY]);
1412 mtx_unlock(&bqlocks[QUEUE_EMPTY]);
1420 * Release bufs from the uma cache back to the buffer queues.
1423 buf_release(void *arg, void **store, int cnt)
1427 for (i = 0; i < cnt; i++)
1428 binsfree(store[i], QUEUE_EMPTY);
1434 * Allocate an empty buffer header.
1441 bp = uma_zalloc(buf_zone, M_NOWAIT);
1443 bufspace_daemonwakeup();
1444 atomic_add_int(&numbufallocfails, 1);
1449 * Wake-up the bufspace daemon on transition.
1451 if (atomic_fetchadd_int(&numfreebuffers, -1) == lofreebuffers)
1452 bufspace_daemonwakeup();
1454 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0)
1455 panic("getnewbuf_empty: Locked buf %p on free queue.", bp);
1457 KASSERT(bp->b_vp == NULL,
1458 ("bp: %p still has vnode %p.", bp, bp->b_vp));
1459 KASSERT((bp->b_flags & (B_DELWRI | B_NOREUSE)) == 0,
1460 ("invalid buffer %p flags %#x", bp, bp->b_flags));
1461 KASSERT((bp->b_xflags & (BX_VNCLEAN|BX_VNDIRTY)) == 0,
1462 ("bp: %p still on a buffer list. xflags %X", bp, bp->b_xflags));
1463 KASSERT(bp->b_npages == 0,
1464 ("bp: %p still has %d vm pages\n", bp, bp->b_npages));
1465 KASSERT(bp->b_kvasize == 0, ("bp: %p still has kva\n", bp));
1466 KASSERT(bp->b_bufsize == 0, ("bp: %p still has bufspace\n", bp));
1473 bp->b_blkno = bp->b_lblkno = 0;
1474 bp->b_offset = NOOFFSET;
1480 bp->b_dirtyoff = bp->b_dirtyend = 0;
1481 bp->b_bufobj = NULL;
1482 bp->b_pin_count = 0;
1483 bp->b_data = bp->b_kvabase = unmapped_buf;
1484 bp->b_fsprivate1 = NULL;
1485 bp->b_fsprivate2 = NULL;
1486 bp->b_fsprivate3 = NULL;
1487 LIST_INIT(&bp->b_dep);
1495 * Free a buffer from the given bufqueue. kva controls whether the
1496 * freed buf must own some kva resources. This is used for
1500 buf_qrecycle(int qindex, bool kva)
1502 struct buf *bp, *nbp;
1505 atomic_add_int(&bufdefragcnt, 1);
1507 mtx_lock(&bqlocks[qindex]);
1508 nbp = TAILQ_FIRST(&bufqueues[qindex]);
1511 * Run scan, possibly freeing data and/or kva mappings on the fly
1514 while ((bp = nbp) != NULL) {
1516 * Calculate next bp (we can only use it if we do not
1517 * release the bqlock).
1519 nbp = TAILQ_NEXT(bp, b_freelist);
1522 * If we are defragging then we need a buffer with
1523 * some kva to reclaim.
1525 if (kva && bp->b_kvasize == 0)
1528 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0)
1532 * Skip buffers with background writes in progress.
1534 if ((bp->b_vflags & BV_BKGRDINPROG) != 0) {
1539 KASSERT(bp->b_qindex == qindex,
1540 ("getnewbuf: inconsistent queue %d bp %p", qindex, bp));
1542 * NOTE: nbp is now entirely invalid. We can only restart
1543 * the scan from this point on.
1546 mtx_unlock(&bqlocks[qindex]);
1549 * Requeue the background write buffer with error and
1552 if ((bp->b_vflags & BV_BKGRDERR) != 0) {
1554 mtx_lock(&bqlocks[qindex]);
1555 nbp = TAILQ_FIRST(&bufqueues[qindex]);
1558 bp->b_flags |= B_INVAL;
1562 mtx_unlock(&bqlocks[qindex]);
1570 * Iterate through all clean queues until we find a buf to recycle or
1571 * exhaust the search.
1574 buf_recycle(bool kva)
1576 int qindex, first_qindex;
1578 qindex = first_qindex = bqcleanq();
1580 if (buf_qrecycle(qindex, kva) == 0)
1582 if (++qindex == QUEUE_CLEAN + clean_queues)
1583 qindex = QUEUE_CLEAN;
1584 } while (qindex != first_qindex);
1592 * Scan the clean queues looking for a buffer to recycle. needsbuffer
1593 * is set on failure so that the caller may optionally bufspace_wait()
1594 * in a race-free fashion.
1597 buf_scan(bool defrag)
1602 * To avoid heavy synchronization and wakeup races we set
1603 * needsbuffer and re-poll before failing. This ensures that
1604 * no frees can be missed between an unsuccessful poll and
1605 * going to sleep in a synchronized fashion.
1607 if ((error = buf_recycle(defrag)) != 0) {
1608 atomic_set_int(&needsbuffer, 1);
1609 bufspace_daemonwakeup();
1610 error = buf_recycle(defrag);
1613 atomic_add_int(&getnewbufrestarts, 1);
1620 * Mark the buffer for removal from the appropriate free list.
1624 bremfree(struct buf *bp)
1627 CTR3(KTR_BUF, "bremfree(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
1628 KASSERT((bp->b_flags & B_REMFREE) == 0,
1629 ("bremfree: buffer %p already marked for delayed removal.", bp));
1630 KASSERT(bp->b_qindex != QUEUE_NONE,
1631 ("bremfree: buffer %p not on a queue.", bp));
1632 BUF_ASSERT_XLOCKED(bp);
1634 bp->b_flags |= B_REMFREE;
1640 * Force an immediate removal from a free list. Used only in nfs when
1641 * it abuses the b_freelist pointer.
1644 bremfreef(struct buf *bp)
1648 qlock = bqlock(bp->b_qindex);
1657 * Removes a buffer from the free list, must be called with the
1658 * correct qlock held.
1661 bremfreel(struct buf *bp)
1664 CTR3(KTR_BUF, "bremfreel(%p) vp %p flags %X",
1665 bp, bp->b_vp, bp->b_flags);
1666 KASSERT(bp->b_qindex != QUEUE_NONE,
1667 ("bremfreel: buffer %p not on a queue.", bp));
1668 if (bp->b_qindex != QUEUE_EMPTY) {
1669 BUF_ASSERT_XLOCKED(bp);
1671 mtx_assert(bqlock(bp->b_qindex), MA_OWNED);
1673 TAILQ_REMOVE(&bufqueues[bp->b_qindex], bp, b_freelist);
1675 KASSERT(bq_len[bp->b_qindex] >= 1, ("queue %d underflow",
1677 bq_len[bp->b_qindex]--;
1679 bp->b_qindex = QUEUE_NONE;
1680 bp->b_flags &= ~B_REMFREE;
1686 * Free the kva allocation for a buffer.
1690 bufkva_free(struct buf *bp)
1694 if (bp->b_kvasize == 0) {
1695 KASSERT(bp->b_kvabase == unmapped_buf &&
1696 bp->b_data == unmapped_buf,
1697 ("Leaked KVA space on %p", bp));
1698 } else if (buf_mapped(bp))
1699 BUF_CHECK_MAPPED(bp);
1701 BUF_CHECK_UNMAPPED(bp);
1703 if (bp->b_kvasize == 0)
1706 vmem_free(buffer_arena, (vm_offset_t)bp->b_kvabase, bp->b_kvasize);
1707 atomic_subtract_long(&bufkvaspace, bp->b_kvasize);
1708 atomic_add_int(&buffreekvacnt, 1);
1709 bp->b_data = bp->b_kvabase = unmapped_buf;
1716 * Allocate the buffer KVA and set b_kvasize and b_kvabase.
1719 bufkva_alloc(struct buf *bp, int maxsize, int gbflags)
1724 KASSERT((gbflags & GB_UNMAPPED) == 0 || (gbflags & GB_KVAALLOC) != 0,
1725 ("Invalid gbflags 0x%x in %s", gbflags, __func__));
1730 error = vmem_alloc(buffer_arena, maxsize, M_BESTFIT | M_NOWAIT, &addr);
1733 * Buffer map is too fragmented. Request the caller
1734 * to defragment the map.
1738 bp->b_kvabase = (caddr_t)addr;
1739 bp->b_kvasize = maxsize;
1740 atomic_add_long(&bufkvaspace, bp->b_kvasize);
1741 if ((gbflags & GB_UNMAPPED) != 0) {
1742 bp->b_data = unmapped_buf;
1743 BUF_CHECK_UNMAPPED(bp);
1745 bp->b_data = bp->b_kvabase;
1746 BUF_CHECK_MAPPED(bp);
1754 * Reclaim buffer kva by freeing buffers holding kva. This is a vmem
1755 * callback that fires to avoid returning failure.
1758 bufkva_reclaim(vmem_t *vmem, int flags)
1762 for (i = 0; i < 5; i++)
1763 if (buf_scan(true) != 0)
1770 * Attempt to initiate asynchronous I/O on read-ahead blocks. We must
1771 * clear BIO_ERROR and B_INVAL prior to initiating I/O . If B_CACHE is set,
1772 * the buffer is valid and we do not have to do anything.
1775 breada(struct vnode * vp, daddr_t * rablkno, int * rabsize,
1776 int cnt, struct ucred * cred)
1781 for (i = 0; i < cnt; i++, rablkno++, rabsize++) {
1782 if (inmem(vp, *rablkno))
1784 rabp = getblk(vp, *rablkno, *rabsize, 0, 0, 0);
1786 if ((rabp->b_flags & B_CACHE) == 0) {
1787 if (!TD_IS_IDLETHREAD(curthread)) {
1791 racct_add_buf(curproc, rabp, 0);
1792 PROC_UNLOCK(curproc);
1795 curthread->td_ru.ru_inblock++;
1797 rabp->b_flags |= B_ASYNC;
1798 rabp->b_flags &= ~B_INVAL;
1799 rabp->b_ioflags &= ~BIO_ERROR;
1800 rabp->b_iocmd = BIO_READ;
1801 if (rabp->b_rcred == NOCRED && cred != NOCRED)
1802 rabp->b_rcred = crhold(cred);
1803 vfs_busy_pages(rabp, 0);
1805 rabp->b_iooffset = dbtob(rabp->b_blkno);
1814 * Entry point for bread() and breadn() via #defines in sys/buf.h.
1816 * Get a buffer with the specified data. Look in the cache first. We
1817 * must clear BIO_ERROR and B_INVAL prior to initiating I/O. If B_CACHE
1818 * is set, the buffer is valid and we do not have to do anything, see
1819 * getblk(). Also starts asynchronous I/O on read-ahead blocks.
1821 * Always return a NULL buffer pointer (in bpp) when returning an error.
1824 breadn_flags(struct vnode *vp, daddr_t blkno, int size, daddr_t *rablkno,
1825 int *rabsize, int cnt, struct ucred *cred, int flags, struct buf **bpp)
1828 int rv = 0, readwait = 0;
1830 CTR3(KTR_BUF, "breadn(%p, %jd, %d)", vp, blkno, size);
1832 * Can only return NULL if GB_LOCK_NOWAIT flag is specified.
1834 *bpp = bp = getblk(vp, blkno, size, 0, 0, flags);
1838 /* if not found in cache, do some I/O */
1839 if ((bp->b_flags & B_CACHE) == 0) {
1840 if (!TD_IS_IDLETHREAD(curthread)) {
1844 racct_add_buf(curproc, bp, 0);
1845 PROC_UNLOCK(curproc);
1848 curthread->td_ru.ru_inblock++;
1850 bp->b_iocmd = BIO_READ;
1851 bp->b_flags &= ~B_INVAL;
1852 bp->b_ioflags &= ~BIO_ERROR;
1853 if (bp->b_rcred == NOCRED && cred != NOCRED)
1854 bp->b_rcred = crhold(cred);
1855 vfs_busy_pages(bp, 0);
1856 bp->b_iooffset = dbtob(bp->b_blkno);
1861 breada(vp, rablkno, rabsize, cnt, cred);
1874 * Write, release buffer on completion. (Done by iodone
1875 * if async). Do not bother writing anything if the buffer
1878 * Note that we set B_CACHE here, indicating that buffer is
1879 * fully valid and thus cacheable. This is true even of NFS
1880 * now so we set it generally. This could be set either here
1881 * or in biodone() since the I/O is synchronous. We put it
1885 bufwrite(struct buf *bp)
1892 CTR3(KTR_BUF, "bufwrite(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
1893 if ((bp->b_bufobj->bo_flag & BO_DEAD) != 0) {
1894 bp->b_flags |= B_INVAL | B_RELBUF;
1895 bp->b_flags &= ~B_CACHE;
1899 if (bp->b_flags & B_INVAL) {
1904 if (bp->b_flags & B_BARRIER)
1907 oldflags = bp->b_flags;
1909 BUF_ASSERT_HELD(bp);
1911 if (bp->b_pin_count > 0)
1914 KASSERT(!(bp->b_vflags & BV_BKGRDINPROG),
1915 ("FFS background buffer should not get here %p", bp));
1919 vp_md = vp->v_vflag & VV_MD;
1924 * Mark the buffer clean. Increment the bufobj write count
1925 * before bundirty() call, to prevent other thread from seeing
1926 * empty dirty list and zero counter for writes in progress,
1927 * falsely indicating that the bufobj is clean.
1929 bufobj_wref(bp->b_bufobj);
1932 bp->b_flags &= ~B_DONE;
1933 bp->b_ioflags &= ~BIO_ERROR;
1934 bp->b_flags |= B_CACHE;
1935 bp->b_iocmd = BIO_WRITE;
1937 vfs_busy_pages(bp, 1);
1940 * Normal bwrites pipeline writes
1942 bp->b_runningbufspace = bp->b_bufsize;
1943 space = atomic_fetchadd_long(&runningbufspace, bp->b_runningbufspace);
1945 if (!TD_IS_IDLETHREAD(curthread)) {
1949 racct_add_buf(curproc, bp, 1);
1950 PROC_UNLOCK(curproc);
1953 curthread->td_ru.ru_oublock++;
1955 if (oldflags & B_ASYNC)
1957 bp->b_iooffset = dbtob(bp->b_blkno);
1960 if ((oldflags & B_ASYNC) == 0) {
1961 int rtval = bufwait(bp);
1964 } else if (space > hirunningspace) {
1966 * don't allow the async write to saturate the I/O
1967 * system. We will not deadlock here because
1968 * we are blocking waiting for I/O that is already in-progress
1969 * to complete. We do not block here if it is the update
1970 * or syncer daemon trying to clean up as that can lead
1973 if ((curthread->td_pflags & TDP_NORUNNINGBUF) == 0 && !vp_md)
1974 waitrunningbufspace();
1981 bufbdflush(struct bufobj *bo, struct buf *bp)
1985 if (bo->bo_dirty.bv_cnt > dirtybufthresh + 10) {
1986 (void) VOP_FSYNC(bp->b_vp, MNT_NOWAIT, curthread);
1988 } else if (bo->bo_dirty.bv_cnt > dirtybufthresh) {
1991 * Try to find a buffer to flush.
1993 TAILQ_FOREACH(nbp, &bo->bo_dirty.bv_hd, b_bobufs) {
1994 if ((nbp->b_vflags & BV_BKGRDINPROG) ||
1996 LK_EXCLUSIVE | LK_NOWAIT, NULL))
1999 panic("bdwrite: found ourselves");
2001 /* Don't countdeps with the bo lock held. */
2002 if (buf_countdeps(nbp, 0)) {
2007 if (nbp->b_flags & B_CLUSTEROK) {
2008 vfs_bio_awrite(nbp);
2013 dirtybufferflushes++;
2022 * Delayed write. (Buffer is marked dirty). Do not bother writing
2023 * anything if the buffer is marked invalid.
2025 * Note that since the buffer must be completely valid, we can safely
2026 * set B_CACHE. In fact, we have to set B_CACHE here rather then in
2027 * biodone() in order to prevent getblk from writing the buffer
2028 * out synchronously.
2031 bdwrite(struct buf *bp)
2033 struct thread *td = curthread;
2037 CTR3(KTR_BUF, "bdwrite(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
2038 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp));
2039 KASSERT((bp->b_flags & B_BARRIER) == 0,
2040 ("Barrier request in delayed write %p", bp));
2041 BUF_ASSERT_HELD(bp);
2043 if (bp->b_flags & B_INVAL) {
2049 * If we have too many dirty buffers, don't create any more.
2050 * If we are wildly over our limit, then force a complete
2051 * cleanup. Otherwise, just keep the situation from getting
2052 * out of control. Note that we have to avoid a recursive
2053 * disaster and not try to clean up after our own cleanup!
2057 if ((td->td_pflags & (TDP_COWINPROGRESS|TDP_INBDFLUSH)) == 0) {
2058 td->td_pflags |= TDP_INBDFLUSH;
2060 td->td_pflags &= ~TDP_INBDFLUSH;
2066 * Set B_CACHE, indicating that the buffer is fully valid. This is
2067 * true even of NFS now.
2069 bp->b_flags |= B_CACHE;
2072 * This bmap keeps the system from needing to do the bmap later,
2073 * perhaps when the system is attempting to do a sync. Since it
2074 * is likely that the indirect block -- or whatever other datastructure
2075 * that the filesystem needs is still in memory now, it is a good
2076 * thing to do this. Note also, that if the pageout daemon is
2077 * requesting a sync -- there might not be enough memory to do
2078 * the bmap then... So, this is important to do.
2080 if (vp->v_type != VCHR && bp->b_lblkno == bp->b_blkno) {
2081 VOP_BMAP(vp, bp->b_lblkno, NULL, &bp->b_blkno, NULL, NULL);
2085 * Set the *dirty* buffer range based upon the VM system dirty
2088 * Mark the buffer pages as clean. We need to do this here to
2089 * satisfy the vnode_pager and the pageout daemon, so that it
2090 * thinks that the pages have been "cleaned". Note that since
2091 * the pages are in a delayed write buffer -- the VFS layer
2092 * "will" see that the pages get written out on the next sync,
2093 * or perhaps the cluster will be completed.
2095 vfs_clean_pages_dirty_buf(bp);
2099 * note: we cannot initiate I/O from a bdwrite even if we wanted to,
2100 * due to the softdep code.
2107 * Turn buffer into delayed write request. We must clear BIO_READ and
2108 * B_RELBUF, and we must set B_DELWRI. We reassign the buffer to
2109 * itself to properly update it in the dirty/clean lists. We mark it
2110 * B_DONE to ensure that any asynchronization of the buffer properly
2111 * clears B_DONE ( else a panic will occur later ).
2113 * bdirty() is kinda like bdwrite() - we have to clear B_INVAL which
2114 * might have been set pre-getblk(). Unlike bwrite/bdwrite, bdirty()
2115 * should only be called if the buffer is known-good.
2117 * Since the buffer is not on a queue, we do not update the numfreebuffers
2120 * The buffer must be on QUEUE_NONE.
2123 bdirty(struct buf *bp)
2126 CTR3(KTR_BUF, "bdirty(%p) vp %p flags %X",
2127 bp, bp->b_vp, bp->b_flags);
2128 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp));
2129 KASSERT(bp->b_flags & B_REMFREE || bp->b_qindex == QUEUE_NONE,
2130 ("bdirty: buffer %p still on queue %d", bp, bp->b_qindex));
2131 BUF_ASSERT_HELD(bp);
2132 bp->b_flags &= ~(B_RELBUF);
2133 bp->b_iocmd = BIO_WRITE;
2135 if ((bp->b_flags & B_DELWRI) == 0) {
2136 bp->b_flags |= /* XXX B_DONE | */ B_DELWRI;
2145 * Clear B_DELWRI for buffer.
2147 * Since the buffer is not on a queue, we do not update the numfreebuffers
2150 * The buffer must be on QUEUE_NONE.
2154 bundirty(struct buf *bp)
2157 CTR3(KTR_BUF, "bundirty(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
2158 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp));
2159 KASSERT(bp->b_flags & B_REMFREE || bp->b_qindex == QUEUE_NONE,
2160 ("bundirty: buffer %p still on queue %d", bp, bp->b_qindex));
2161 BUF_ASSERT_HELD(bp);
2163 if (bp->b_flags & B_DELWRI) {
2164 bp->b_flags &= ~B_DELWRI;
2169 * Since it is now being written, we can clear its deferred write flag.
2171 bp->b_flags &= ~B_DEFERRED;
2177 * Asynchronous write. Start output on a buffer, but do not wait for
2178 * it to complete. The buffer is released when the output completes.
2180 * bwrite() ( or the VOP routine anyway ) is responsible for handling
2181 * B_INVAL buffers. Not us.
2184 bawrite(struct buf *bp)
2187 bp->b_flags |= B_ASYNC;
2194 * Asynchronous barrier write. Start output on a buffer, but do not
2195 * wait for it to complete. Place a write barrier after this write so
2196 * that this buffer and all buffers written before it are committed to
2197 * the disk before any buffers written after this write are committed
2198 * to the disk. The buffer is released when the output completes.
2201 babarrierwrite(struct buf *bp)
2204 bp->b_flags |= B_ASYNC | B_BARRIER;
2211 * Synchronous barrier write. Start output on a buffer and wait for
2212 * it to complete. Place a write barrier after this write so that
2213 * this buffer and all buffers written before it are committed to
2214 * the disk before any buffers written after this write are committed
2215 * to the disk. The buffer is released when the output completes.
2218 bbarrierwrite(struct buf *bp)
2221 bp->b_flags |= B_BARRIER;
2222 return (bwrite(bp));
2228 * Called prior to the locking of any vnodes when we are expecting to
2229 * write. We do not want to starve the buffer cache with too many
2230 * dirty buffers so we block here. By blocking prior to the locking
2231 * of any vnodes we attempt to avoid the situation where a locked vnode
2232 * prevents the various system daemons from flushing related buffers.
2238 if (numdirtybuffers >= hidirtybuffers) {
2239 mtx_lock(&bdirtylock);
2240 while (numdirtybuffers >= hidirtybuffers) {
2242 msleep(&bdirtywait, &bdirtylock, (PRIBIO + 4),
2245 mtx_unlock(&bdirtylock);
2250 * Return true if we have too many dirty buffers.
2253 buf_dirty_count_severe(void)
2256 return(numdirtybuffers >= hidirtybuffers);
2262 * Release a busy buffer and, if requested, free its resources. The
2263 * buffer will be stashed in the appropriate bufqueue[] allowing it
2264 * to be accessed later as a cache entity or reused for other purposes.
2267 brelse(struct buf *bp)
2272 * Many functions erroneously call brelse with a NULL bp under rare
2273 * error conditions. Simply return when called with a NULL bp.
2277 CTR3(KTR_BUF, "brelse(%p) vp %p flags %X",
2278 bp, bp->b_vp, bp->b_flags);
2279 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)),
2280 ("brelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp));
2281 KASSERT((bp->b_flags & B_VMIO) != 0 || (bp->b_flags & B_NOREUSE) == 0,
2282 ("brelse: non-VMIO buffer marked NOREUSE"));
2284 if (BUF_LOCKRECURSED(bp)) {
2286 * Do not process, in particular, do not handle the
2287 * B_INVAL/B_RELBUF and do not release to free list.
2293 if (bp->b_flags & B_MANAGED) {
2298 if ((bp->b_vflags & (BV_BKGRDINPROG | BV_BKGRDERR)) == BV_BKGRDERR) {
2299 BO_LOCK(bp->b_bufobj);
2300 bp->b_vflags &= ~BV_BKGRDERR;
2301 BO_UNLOCK(bp->b_bufobj);
2304 if (bp->b_iocmd == BIO_WRITE && (bp->b_ioflags & BIO_ERROR) &&
2305 !(bp->b_flags & B_INVAL)) {
2307 * Failed write, redirty. Must clear BIO_ERROR to prevent
2308 * pages from being scrapped.
2310 bp->b_ioflags &= ~BIO_ERROR;
2312 } else if ((bp->b_flags & (B_NOCACHE | B_INVAL)) ||
2313 (bp->b_ioflags & BIO_ERROR) || (bp->b_bufsize <= 0)) {
2315 * Either a failed read I/O or we were asked to free or not
2318 bp->b_flags |= B_INVAL;
2319 if (!LIST_EMPTY(&bp->b_dep))
2321 if (bp->b_flags & B_DELWRI)
2323 bp->b_flags &= ~(B_DELWRI | B_CACHE);
2324 if ((bp->b_flags & B_VMIO) == 0) {
2332 * We must clear B_RELBUF if B_DELWRI is set. If vfs_vmio_truncate()
2333 * is called with B_DELWRI set, the underlying pages may wind up
2334 * getting freed causing a previous write (bdwrite()) to get 'lost'
2335 * because pages associated with a B_DELWRI bp are marked clean.
2337 * We still allow the B_INVAL case to call vfs_vmio_truncate(), even
2338 * if B_DELWRI is set.
2340 if (bp->b_flags & B_DELWRI)
2341 bp->b_flags &= ~B_RELBUF;
2344 * VMIO buffer rundown. It is not very necessary to keep a VMIO buffer
2345 * constituted, not even NFS buffers now. Two flags effect this. If
2346 * B_INVAL, the struct buf is invalidated but the VM object is kept
2347 * around ( i.e. so it is trivial to reconstitute the buffer later ).
2349 * If BIO_ERROR or B_NOCACHE is set, pages in the VM object will be
2350 * invalidated. BIO_ERROR cannot be set for a failed write unless the
2351 * buffer is also B_INVAL because it hits the re-dirtying code above.
2353 * Normally we can do this whether a buffer is B_DELWRI or not. If
2354 * the buffer is an NFS buffer, it is tracking piecemeal writes or
2355 * the commit state and we cannot afford to lose the buffer. If the
2356 * buffer has a background write in progress, we need to keep it
2357 * around to prevent it from being reconstituted and starting a second
2360 if ((bp->b_flags & B_VMIO) && (bp->b_flags & B_NOCACHE ||
2361 (bp->b_ioflags & BIO_ERROR && bp->b_iocmd == BIO_READ)) &&
2362 !(bp->b_vp->v_mount != NULL &&
2363 (bp->b_vp->v_mount->mnt_vfc->vfc_flags & VFCF_NETWORK) != 0 &&
2364 !vn_isdisk(bp->b_vp, NULL) && (bp->b_flags & B_DELWRI))) {
2365 vfs_vmio_invalidate(bp);
2369 if ((bp->b_flags & (B_INVAL | B_RELBUF)) != 0 ||
2370 (bp->b_flags & (B_DELWRI | B_NOREUSE)) == B_NOREUSE) {
2372 bp->b_flags &= ~B_NOREUSE;
2373 if (bp->b_vp != NULL)
2378 * If the buffer has junk contents signal it and eventually
2379 * clean up B_DELWRI and diassociate the vnode so that gbincore()
2382 if (bp->b_bufsize == 0 || (bp->b_ioflags & BIO_ERROR) != 0 ||
2383 (bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF)) != 0)
2384 bp->b_flags |= B_INVAL;
2385 if (bp->b_flags & B_INVAL) {
2386 if (bp->b_flags & B_DELWRI)
2392 /* buffers with no memory */
2393 if (bp->b_bufsize == 0) {
2397 /* buffers with junk contents */
2398 if (bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF) ||
2399 (bp->b_ioflags & BIO_ERROR)) {
2400 bp->b_xflags &= ~(BX_BKGRDWRITE | BX_ALTDATA);
2401 if (bp->b_vflags & BV_BKGRDINPROG)
2402 panic("losing buffer 2");
2403 qindex = QUEUE_CLEAN;
2404 bp->b_flags |= B_AGE;
2405 /* remaining buffers */
2406 } else if (bp->b_flags & B_DELWRI)
2407 qindex = QUEUE_DIRTY;
2409 qindex = QUEUE_CLEAN;
2411 binsfree(bp, qindex);
2413 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF | B_DIRECT);
2414 if ((bp->b_flags & B_DELWRI) == 0 && (bp->b_xflags & BX_VNDIRTY))
2415 panic("brelse: not dirty");
2418 if (qindex == QUEUE_CLEAN)
2423 * Release a buffer back to the appropriate queue but do not try to free
2424 * it. The buffer is expected to be used again soon.
2426 * bqrelse() is used by bdwrite() to requeue a delayed write, and used by
2427 * biodone() to requeue an async I/O on completion. It is also used when
2428 * known good buffers need to be requeued but we think we may need the data
2431 * XXX we should be able to leave the B_RELBUF hint set on completion.
2434 bqrelse(struct buf *bp)
2438 CTR3(KTR_BUF, "bqrelse(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
2439 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)),
2440 ("bqrelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp));
2442 qindex = QUEUE_NONE;
2443 if (BUF_LOCKRECURSED(bp)) {
2444 /* do not release to free list */
2448 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF);
2450 if (bp->b_flags & B_MANAGED) {
2451 if (bp->b_flags & B_REMFREE)
2456 /* buffers with stale but valid contents */
2457 if ((bp->b_flags & B_DELWRI) != 0 || (bp->b_vflags & (BV_BKGRDINPROG |
2458 BV_BKGRDERR)) == BV_BKGRDERR) {
2459 BO_LOCK(bp->b_bufobj);
2460 bp->b_vflags &= ~BV_BKGRDERR;
2461 BO_UNLOCK(bp->b_bufobj);
2462 qindex = QUEUE_DIRTY;
2464 if ((bp->b_flags & B_DELWRI) == 0 &&
2465 (bp->b_xflags & BX_VNDIRTY))
2466 panic("bqrelse: not dirty");
2467 if ((bp->b_flags & B_NOREUSE) != 0) {
2471 qindex = QUEUE_CLEAN;
2473 binsfree(bp, qindex);
2478 if (qindex == QUEUE_CLEAN)
2483 * Complete I/O to a VMIO backed page. Validate the pages as appropriate,
2484 * restore bogus pages.
2487 vfs_vmio_iodone(struct buf *bp)
2493 int bogus, i, iosize;
2495 obj = bp->b_bufobj->bo_object;
2496 KASSERT(obj->paging_in_progress >= bp->b_npages,
2497 ("vfs_vmio_iodone: paging in progress(%d) < b_npages(%d)",
2498 obj->paging_in_progress, bp->b_npages));
2501 KASSERT(vp->v_holdcnt > 0,
2502 ("vfs_vmio_iodone: vnode %p has zero hold count", vp));
2503 KASSERT(vp->v_object != NULL,
2504 ("vfs_vmio_iodone: vnode %p has no vm_object", vp));
2506 foff = bp->b_offset;
2507 KASSERT(bp->b_offset != NOOFFSET,
2508 ("vfs_vmio_iodone: bp %p has no buffer offset", bp));
2511 iosize = bp->b_bcount - bp->b_resid;
2512 VM_OBJECT_WLOCK(obj);
2513 for (i = 0; i < bp->b_npages; i++) {
2516 resid = ((foff + PAGE_SIZE) & ~(off_t)PAGE_MASK) - foff;
2521 * cleanup bogus pages, restoring the originals
2524 if (m == bogus_page) {
2526 m = vm_page_lookup(obj, OFF_TO_IDX(foff));
2528 panic("biodone: page disappeared!");
2530 } else if ((bp->b_iocmd == BIO_READ) && resid > 0) {
2532 * In the write case, the valid and clean bits are
2533 * already changed correctly ( see bdwrite() ), so we
2534 * only need to do this here in the read case.
2536 KASSERT((m->dirty & vm_page_bits(foff & PAGE_MASK,
2537 resid)) == 0, ("vfs_vmio_iodone: page %p "
2538 "has unexpected dirty bits", m));
2539 vfs_page_set_valid(bp, foff, m);
2541 KASSERT(OFF_TO_IDX(foff) == m->pindex,
2542 ("vfs_vmio_iodone: foff(%jd)/pindex(%ju) mismatch",
2543 (intmax_t)foff, (uintmax_t)m->pindex));
2546 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK;
2549 vm_object_pip_wakeupn(obj, bp->b_npages);
2550 VM_OBJECT_WUNLOCK(obj);
2551 if (bogus && buf_mapped(bp)) {
2552 BUF_CHECK_MAPPED(bp);
2553 pmap_qenter(trunc_page((vm_offset_t)bp->b_data),
2554 bp->b_pages, bp->b_npages);
2559 * Unwire a page held by a buf and place it on the appropriate vm queue.
2562 vfs_vmio_unwire(struct buf *bp, vm_page_t m)
2567 if (vm_page_unwire(m, PQ_NONE)) {
2569 * Determine if the page should be freed before adding
2570 * it to the inactive queue.
2572 if (m->valid == 0) {
2573 freed = !vm_page_busied(m);
2576 } else if ((bp->b_flags & B_DIRECT) != 0)
2577 freed = vm_page_try_to_free(m);
2582 * If the page is unlikely to be reused, let the
2583 * VM know. Otherwise, maintain LRU page
2584 * ordering and put the page at the tail of the
2587 if ((bp->b_flags & B_NOREUSE) != 0)
2588 vm_page_deactivate_noreuse(m);
2590 vm_page_deactivate(m);
2597 * Perform page invalidation when a buffer is released. The fully invalid
2598 * pages will be reclaimed later in vfs_vmio_truncate().
2601 vfs_vmio_invalidate(struct buf *bp)
2605 int i, resid, poffset, presid;
2607 if (buf_mapped(bp)) {
2608 BUF_CHECK_MAPPED(bp);
2609 pmap_qremove(trunc_page((vm_offset_t)bp->b_data), bp->b_npages);
2611 BUF_CHECK_UNMAPPED(bp);
2613 * Get the base offset and length of the buffer. Note that
2614 * in the VMIO case if the buffer block size is not
2615 * page-aligned then b_data pointer may not be page-aligned.
2616 * But our b_pages[] array *IS* page aligned.
2618 * block sizes less then DEV_BSIZE (usually 512) are not
2619 * supported due to the page granularity bits (m->valid,
2620 * m->dirty, etc...).
2622 * See man buf(9) for more information
2624 obj = bp->b_bufobj->bo_object;
2625 resid = bp->b_bufsize;
2626 poffset = bp->b_offset & PAGE_MASK;
2627 VM_OBJECT_WLOCK(obj);
2628 for (i = 0; i < bp->b_npages; i++) {
2630 if (m == bogus_page)
2631 panic("vfs_vmio_invalidate: Unexpected bogus page.");
2632 bp->b_pages[i] = NULL;
2634 presid = resid > (PAGE_SIZE - poffset) ?
2635 (PAGE_SIZE - poffset) : resid;
2636 KASSERT(presid >= 0, ("brelse: extra page"));
2637 while (vm_page_xbusied(m)) {
2639 VM_OBJECT_WUNLOCK(obj);
2640 vm_page_busy_sleep(m, "mbncsh");
2641 VM_OBJECT_WLOCK(obj);
2643 if (pmap_page_wired_mappings(m) == 0)
2644 vm_page_set_invalid(m, poffset, presid);
2645 vfs_vmio_unwire(bp, m);
2649 VM_OBJECT_WUNLOCK(obj);
2654 * Page-granular truncation of an existing VMIO buffer.
2657 vfs_vmio_truncate(struct buf *bp, int desiredpages)
2663 if (bp->b_npages == desiredpages)
2666 if (buf_mapped(bp)) {
2667 BUF_CHECK_MAPPED(bp);
2668 pmap_qremove((vm_offset_t)trunc_page((vm_offset_t)bp->b_data) +
2669 (desiredpages << PAGE_SHIFT), bp->b_npages - desiredpages);
2671 BUF_CHECK_UNMAPPED(bp);
2672 obj = bp->b_bufobj->bo_object;
2674 VM_OBJECT_WLOCK(obj);
2675 for (i = desiredpages; i < bp->b_npages; i++) {
2677 KASSERT(m != bogus_page, ("allocbuf: bogus page found"));
2678 bp->b_pages[i] = NULL;
2679 vfs_vmio_unwire(bp, m);
2682 VM_OBJECT_WUNLOCK(obj);
2683 bp->b_npages = desiredpages;
2687 * Byte granular extension of VMIO buffers.
2690 vfs_vmio_extend(struct buf *bp, int desiredpages, int size)
2693 * We are growing the buffer, possibly in a
2694 * byte-granular fashion.
2702 * Step 1, bring in the VM pages from the object, allocating
2703 * them if necessary. We must clear B_CACHE if these pages
2704 * are not valid for the range covered by the buffer.
2706 obj = bp->b_bufobj->bo_object;
2707 VM_OBJECT_WLOCK(obj);
2708 while (bp->b_npages < desiredpages) {
2710 * We must allocate system pages since blocking
2711 * here could interfere with paging I/O, no
2712 * matter which process we are.
2714 * Only exclusive busy can be tested here.
2715 * Blocking on shared busy might lead to
2716 * deadlocks once allocbuf() is called after
2717 * pages are vfs_busy_pages().
2719 m = vm_page_grab(obj, OFF_TO_IDX(bp->b_offset) + bp->b_npages,
2720 VM_ALLOC_NOBUSY | VM_ALLOC_SYSTEM |
2721 VM_ALLOC_WIRED | VM_ALLOC_IGN_SBUSY |
2722 VM_ALLOC_COUNT(desiredpages - bp->b_npages));
2724 bp->b_flags &= ~B_CACHE;
2725 bp->b_pages[bp->b_npages] = m;
2730 * Step 2. We've loaded the pages into the buffer,
2731 * we have to figure out if we can still have B_CACHE
2732 * set. Note that B_CACHE is set according to the
2733 * byte-granular range ( bcount and size ), not the
2734 * aligned range ( newbsize ).
2736 * The VM test is against m->valid, which is DEV_BSIZE
2737 * aligned. Needless to say, the validity of the data
2738 * needs to also be DEV_BSIZE aligned. Note that this
2739 * fails with NFS if the server or some other client
2740 * extends the file's EOF. If our buffer is resized,
2741 * B_CACHE may remain set! XXX
2743 toff = bp->b_bcount;
2744 tinc = PAGE_SIZE - ((bp->b_offset + toff) & PAGE_MASK);
2745 while ((bp->b_flags & B_CACHE) && toff < size) {
2748 if (tinc > (size - toff))
2750 pi = ((bp->b_offset & PAGE_MASK) + toff) >> PAGE_SHIFT;
2751 m = bp->b_pages[pi];
2752 vfs_buf_test_cache(bp, bp->b_offset, toff, tinc, m);
2756 VM_OBJECT_WUNLOCK(obj);
2759 * Step 3, fixup the KVA pmap.
2764 BUF_CHECK_UNMAPPED(bp);
2768 * Check to see if a block at a particular lbn is available for a clustered
2772 vfs_bio_clcheck(struct vnode *vp, int size, daddr_t lblkno, daddr_t blkno)
2779 /* If the buf isn't in core skip it */
2780 if ((bpa = gbincore(&vp->v_bufobj, lblkno)) == NULL)
2783 /* If the buf is busy we don't want to wait for it */
2784 if (BUF_LOCK(bpa, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0)
2787 /* Only cluster with valid clusterable delayed write buffers */
2788 if ((bpa->b_flags & (B_DELWRI | B_CLUSTEROK | B_INVAL)) !=
2789 (B_DELWRI | B_CLUSTEROK))
2792 if (bpa->b_bufsize != size)
2796 * Check to see if it is in the expected place on disk and that the
2797 * block has been mapped.
2799 if ((bpa->b_blkno != bpa->b_lblkno) && (bpa->b_blkno == blkno))
2809 * Implement clustered async writes for clearing out B_DELWRI buffers.
2810 * This is much better then the old way of writing only one buffer at
2811 * a time. Note that we may not be presented with the buffers in the
2812 * correct order, so we search for the cluster in both directions.
2815 vfs_bio_awrite(struct buf *bp)
2820 daddr_t lblkno = bp->b_lblkno;
2821 struct vnode *vp = bp->b_vp;
2829 gbflags = (bp->b_data == unmapped_buf) ? GB_UNMAPPED : 0;
2831 * right now we support clustered writing only to regular files. If
2832 * we find a clusterable block we could be in the middle of a cluster
2833 * rather then at the beginning.
2835 if ((vp->v_type == VREG) &&
2836 (vp->v_mount != 0) && /* Only on nodes that have the size info */
2837 (bp->b_flags & (B_CLUSTEROK | B_INVAL)) == B_CLUSTEROK) {
2839 size = vp->v_mount->mnt_stat.f_iosize;
2840 maxcl = MAXPHYS / size;
2843 for (i = 1; i < maxcl; i++)
2844 if (vfs_bio_clcheck(vp, size, lblkno + i,
2845 bp->b_blkno + ((i * size) >> DEV_BSHIFT)) == 0)
2848 for (j = 1; i + j <= maxcl && j <= lblkno; j++)
2849 if (vfs_bio_clcheck(vp, size, lblkno - j,
2850 bp->b_blkno - ((j * size) >> DEV_BSHIFT)) == 0)
2856 * this is a possible cluster write
2860 nwritten = cluster_wbuild(vp, size, lblkno - j, ncl,
2866 bp->b_flags |= B_ASYNC;
2868 * default (old) behavior, writing out only one block
2870 * XXX returns b_bufsize instead of b_bcount for nwritten?
2872 nwritten = bp->b_bufsize;
2881 * Allocate KVA for an empty buf header according to gbflags.
2884 getnewbuf_kva(struct buf *bp, int gbflags, int maxsize)
2887 if ((gbflags & (GB_UNMAPPED | GB_KVAALLOC)) != GB_UNMAPPED) {
2889 * In order to keep fragmentation sane we only allocate kva
2890 * in BKVASIZE chunks. XXX with vmem we can do page size.
2892 maxsize = (maxsize + BKVAMASK) & ~BKVAMASK;
2894 if (maxsize != bp->b_kvasize &&
2895 bufkva_alloc(bp, maxsize, gbflags))
2904 * Find and initialize a new buffer header, freeing up existing buffers
2905 * in the bufqueues as necessary. The new buffer is returned locked.
2908 * We have insufficient buffer headers
2909 * We have insufficient buffer space
2910 * buffer_arena is too fragmented ( space reservation fails )
2911 * If we have to flush dirty buffers ( but we try to avoid this )
2913 * The caller is responsible for releasing the reserved bufspace after
2914 * allocbuf() is called.
2917 getnewbuf(struct vnode *vp, int slpflag, int slptimeo, int maxsize, int gbflags)
2920 bool metadata, reserved;
2923 KASSERT((gbflags & (GB_UNMAPPED | GB_KVAALLOC)) != GB_KVAALLOC,
2924 ("GB_KVAALLOC only makes sense with GB_UNMAPPED"));
2925 if (!unmapped_buf_allowed)
2926 gbflags &= ~(GB_UNMAPPED | GB_KVAALLOC);
2928 if (vp == NULL || (vp->v_vflag & (VV_MD | VV_SYSTEM)) != 0 ||
2933 atomic_add_int(&getnewbufcalls, 1);
2936 if (reserved == false &&
2937 bufspace_reserve(maxsize, metadata) != 0)
2940 if ((bp = buf_alloc()) == NULL)
2942 if (getnewbuf_kva(bp, gbflags, maxsize) == 0)
2945 } while(buf_scan(false) == 0);
2948 atomic_subtract_long(&bufspace, maxsize);
2950 bp->b_flags |= B_INVAL;
2953 bufspace_wait(vp, gbflags, slpflag, slptimeo);
2961 * buffer flushing daemon. Buffers are normally flushed by the
2962 * update daemon but if it cannot keep up this process starts to
2963 * take the load in an attempt to prevent getnewbuf() from blocking.
2965 static struct kproc_desc buf_kp = {
2970 SYSINIT(bufdaemon, SI_SUB_KTHREAD_BUF, SI_ORDER_FIRST, kproc_start, &buf_kp);
2973 buf_flush(struct vnode *vp, int target)
2977 flushed = flushbufqueues(vp, target, 0);
2980 * Could not find any buffers without rollback
2981 * dependencies, so just write the first one
2982 * in the hopes of eventually making progress.
2984 if (vp != NULL && target > 2)
2986 flushbufqueues(vp, target, 1);
2997 * This process needs to be suspended prior to shutdown sync.
2999 EVENTHANDLER_REGISTER(shutdown_pre_sync, kproc_shutdown, bufdaemonproc,
3003 * This process is allowed to take the buffer cache to the limit
3005 curthread->td_pflags |= TDP_NORUNNINGBUF | TDP_BUFNEED;
3009 mtx_unlock(&bdlock);
3011 kproc_suspend_check(bufdaemonproc);
3012 lodirty = lodirtybuffers;
3013 if (bd_speedupreq) {
3014 lodirty = numdirtybuffers / 2;
3018 * Do the flush. Limit the amount of in-transit I/O we
3019 * allow to build up, otherwise we would completely saturate
3022 while (numdirtybuffers > lodirty) {
3023 if (buf_flush(NULL, numdirtybuffers - lodirty) == 0)
3025 kern_yield(PRI_USER);
3029 * Only clear bd_request if we have reached our low water
3030 * mark. The buf_daemon normally waits 1 second and
3031 * then incrementally flushes any dirty buffers that have
3032 * built up, within reason.
3034 * If we were unable to hit our low water mark and couldn't
3035 * find any flushable buffers, we sleep for a short period
3036 * to avoid endless loops on unlockable buffers.
3039 if (numdirtybuffers <= lodirtybuffers) {
3041 * We reached our low water mark, reset the
3042 * request and sleep until we are needed again.
3043 * The sleep is just so the suspend code works.
3047 * Do an extra wakeup in case dirty threshold
3048 * changed via sysctl and the explicit transition
3049 * out of shortfall was missed.
3052 if (runningbufspace <= lorunningspace)
3054 msleep(&bd_request, &bdlock, PVM, "psleep", hz);
3057 * We couldn't find any flushable dirty buffers but
3058 * still have too many dirty buffers, we
3059 * have to sleep and try again. (rare)
3061 msleep(&bd_request, &bdlock, PVM, "qsleep", hz / 10);
3069 * Try to flush a buffer in the dirty queue. We must be careful to
3070 * free up B_INVAL buffers instead of write them, which NFS is
3071 * particularly sensitive to.
3073 static int flushwithdeps = 0;
3074 SYSCTL_INT(_vfs, OID_AUTO, flushwithdeps, CTLFLAG_RW, &flushwithdeps,
3075 0, "Number of buffers flushed with dependecies that require rollbacks");
3078 flushbufqueues(struct vnode *lvp, int target, int flushdeps)
3080 struct buf *sentinel;
3091 queue = QUEUE_DIRTY;
3093 sentinel = malloc(sizeof(struct buf), M_TEMP, M_WAITOK | M_ZERO);
3094 sentinel->b_qindex = QUEUE_SENTINEL;
3095 mtx_lock(&bqlocks[queue]);
3096 TAILQ_INSERT_HEAD(&bufqueues[queue], sentinel, b_freelist);
3097 mtx_unlock(&bqlocks[queue]);
3098 while (flushed != target) {
3100 mtx_lock(&bqlocks[queue]);
3101 bp = TAILQ_NEXT(sentinel, b_freelist);
3103 TAILQ_REMOVE(&bufqueues[queue], sentinel, b_freelist);
3104 TAILQ_INSERT_AFTER(&bufqueues[queue], bp, sentinel,
3107 mtx_unlock(&bqlocks[queue]);
3111 * Skip sentinels inserted by other invocations of the
3112 * flushbufqueues(), taking care to not reorder them.
3114 * Only flush the buffers that belong to the
3115 * vnode locked by the curthread.
3117 if (bp->b_qindex == QUEUE_SENTINEL || (lvp != NULL &&
3119 mtx_unlock(&bqlocks[queue]);
3122 error = BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL);
3123 mtx_unlock(&bqlocks[queue]);
3126 if (bp->b_pin_count > 0) {
3131 * BKGRDINPROG can only be set with the buf and bufobj
3132 * locks both held. We tolerate a race to clear it here.
3134 if ((bp->b_vflags & BV_BKGRDINPROG) != 0 ||
3135 (bp->b_flags & B_DELWRI) == 0) {
3139 if (bp->b_flags & B_INVAL) {
3146 if (!LIST_EMPTY(&bp->b_dep) && buf_countdeps(bp, 0)) {
3147 if (flushdeps == 0) {
3155 * We must hold the lock on a vnode before writing
3156 * one of its buffers. Otherwise we may confuse, or
3157 * in the case of a snapshot vnode, deadlock the
3160 * The lock order here is the reverse of the normal
3161 * of vnode followed by buf lock. This is ok because
3162 * the NOWAIT will prevent deadlock.
3165 if (vn_start_write(vp, &mp, V_NOWAIT) != 0) {
3171 error = vn_lock(vp, LK_EXCLUSIVE | LK_NOWAIT);
3173 ASSERT_VOP_LOCKED(vp, "getbuf");
3175 error = VOP_ISLOCKED(vp) == LK_EXCLUSIVE ? 0 :
3176 vn_lock(vp, LK_TRYUPGRADE);
3179 CTR3(KTR_BUF, "flushbufqueue(%p) vp %p flags %X",
3180 bp, bp->b_vp, bp->b_flags);
3181 if (curproc == bufdaemonproc) {
3188 vn_finished_write(mp);
3191 flushwithdeps += hasdeps;
3195 * Sleeping on runningbufspace while holding
3196 * vnode lock leads to deadlock.
3198 if (curproc == bufdaemonproc &&
3199 runningbufspace > hirunningspace)
3200 waitrunningbufspace();
3203 vn_finished_write(mp);
3206 mtx_lock(&bqlocks[queue]);
3207 TAILQ_REMOVE(&bufqueues[queue], sentinel, b_freelist);
3208 mtx_unlock(&bqlocks[queue]);
3209 free(sentinel, M_TEMP);
3214 * Check to see if a block is currently memory resident.
3217 incore(struct bufobj *bo, daddr_t blkno)
3222 bp = gbincore(bo, blkno);
3228 * Returns true if no I/O is needed to access the
3229 * associated VM object. This is like incore except
3230 * it also hunts around in the VM system for the data.
3234 inmem(struct vnode * vp, daddr_t blkno)
3237 vm_offset_t toff, tinc, size;
3241 ASSERT_VOP_LOCKED(vp, "inmem");
3243 if (incore(&vp->v_bufobj, blkno))
3245 if (vp->v_mount == NULL)
3252 if (size > vp->v_mount->mnt_stat.f_iosize)
3253 size = vp->v_mount->mnt_stat.f_iosize;
3254 off = (vm_ooffset_t)blkno * (vm_ooffset_t)vp->v_mount->mnt_stat.f_iosize;
3256 VM_OBJECT_RLOCK(obj);
3257 for (toff = 0; toff < vp->v_mount->mnt_stat.f_iosize; toff += tinc) {
3258 m = vm_page_lookup(obj, OFF_TO_IDX(off + toff));
3262 if (tinc > PAGE_SIZE - ((toff + off) & PAGE_MASK))
3263 tinc = PAGE_SIZE - ((toff + off) & PAGE_MASK);
3264 if (vm_page_is_valid(m,
3265 (vm_offset_t) ((toff + off) & PAGE_MASK), tinc) == 0)
3268 VM_OBJECT_RUNLOCK(obj);
3272 VM_OBJECT_RUNLOCK(obj);
3277 * Set the dirty range for a buffer based on the status of the dirty
3278 * bits in the pages comprising the buffer. The range is limited
3279 * to the size of the buffer.
3281 * Tell the VM system that the pages associated with this buffer
3282 * are clean. This is used for delayed writes where the data is
3283 * going to go to disk eventually without additional VM intevention.
3285 * Note that while we only really need to clean through to b_bcount, we
3286 * just go ahead and clean through to b_bufsize.
3289 vfs_clean_pages_dirty_buf(struct buf *bp)
3291 vm_ooffset_t foff, noff, eoff;
3295 if ((bp->b_flags & B_VMIO) == 0 || bp->b_bufsize == 0)
3298 foff = bp->b_offset;
3299 KASSERT(bp->b_offset != NOOFFSET,
3300 ("vfs_clean_pages_dirty_buf: no buffer offset"));
3302 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object);
3303 vfs_drain_busy_pages(bp);
3304 vfs_setdirty_locked_object(bp);
3305 for (i = 0; i < bp->b_npages; i++) {
3306 noff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK;
3308 if (eoff > bp->b_offset + bp->b_bufsize)
3309 eoff = bp->b_offset + bp->b_bufsize;
3311 vfs_page_set_validclean(bp, foff, m);
3312 /* vm_page_clear_dirty(m, foff & PAGE_MASK, eoff - foff); */
3315 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object);
3319 vfs_setdirty_locked_object(struct buf *bp)
3324 object = bp->b_bufobj->bo_object;
3325 VM_OBJECT_ASSERT_WLOCKED(object);
3328 * We qualify the scan for modified pages on whether the
3329 * object has been flushed yet.
3331 if ((object->flags & OBJ_MIGHTBEDIRTY) != 0) {
3332 vm_offset_t boffset;
3333 vm_offset_t eoffset;
3336 * test the pages to see if they have been modified directly
3337 * by users through the VM system.
3339 for (i = 0; i < bp->b_npages; i++)
3340 vm_page_test_dirty(bp->b_pages[i]);
3343 * Calculate the encompassing dirty range, boffset and eoffset,
3344 * (eoffset - boffset) bytes.
3347 for (i = 0; i < bp->b_npages; i++) {
3348 if (bp->b_pages[i]->dirty)
3351 boffset = (i << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK);
3353 for (i = bp->b_npages - 1; i >= 0; --i) {
3354 if (bp->b_pages[i]->dirty) {
3358 eoffset = ((i + 1) << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK);
3361 * Fit it to the buffer.
3364 if (eoffset > bp->b_bcount)
3365 eoffset = bp->b_bcount;
3368 * If we have a good dirty range, merge with the existing
3372 if (boffset < eoffset) {
3373 if (bp->b_dirtyoff > boffset)
3374 bp->b_dirtyoff = boffset;
3375 if (bp->b_dirtyend < eoffset)
3376 bp->b_dirtyend = eoffset;
3382 * Allocate the KVA mapping for an existing buffer.
3383 * If an unmapped buffer is provided but a mapped buffer is requested, take
3384 * also care to properly setup mappings between pages and KVA.
3387 bp_unmapped_get_kva(struct buf *bp, daddr_t blkno, int size, int gbflags)
3389 int bsize, maxsize, need_mapping, need_kva;
3392 need_mapping = bp->b_data == unmapped_buf &&
3393 (gbflags & GB_UNMAPPED) == 0;
3394 need_kva = bp->b_kvabase == unmapped_buf &&
3395 bp->b_data == unmapped_buf &&
3396 (gbflags & GB_KVAALLOC) != 0;
3397 if (!need_mapping && !need_kva)
3400 BUF_CHECK_UNMAPPED(bp);
3402 if (need_mapping && bp->b_kvabase != unmapped_buf) {
3404 * Buffer is not mapped, but the KVA was already
3405 * reserved at the time of the instantiation. Use the
3412 * Calculate the amount of the address space we would reserve
3413 * if the buffer was mapped.
3415 bsize = vn_isdisk(bp->b_vp, NULL) ? DEV_BSIZE : bp->b_bufobj->bo_bsize;
3416 KASSERT(bsize != 0, ("bsize == 0, check bo->bo_bsize"));
3417 offset = blkno * bsize;
3418 maxsize = size + (offset & PAGE_MASK);
3419 maxsize = imax(maxsize, bsize);
3421 while (bufkva_alloc(bp, maxsize, gbflags) != 0) {
3422 if ((gbflags & GB_NOWAIT_BD) != 0) {
3424 * XXXKIB: defragmentation cannot
3425 * succeed, not sure what else to do.
3427 panic("GB_NOWAIT_BD and GB_UNMAPPED %p", bp);
3429 atomic_add_int(&mappingrestarts, 1);
3430 bufspace_wait(bp->b_vp, gbflags, 0, 0);
3434 /* b_offset is handled by bpmap_qenter. */
3435 bp->b_data = bp->b_kvabase;
3436 BUF_CHECK_MAPPED(bp);
3444 * Get a block given a specified block and offset into a file/device.
3445 * The buffers B_DONE bit will be cleared on return, making it almost
3446 * ready for an I/O initiation. B_INVAL may or may not be set on
3447 * return. The caller should clear B_INVAL prior to initiating a
3450 * For a non-VMIO buffer, B_CACHE is set to the opposite of B_INVAL for
3451 * an existing buffer.
3453 * For a VMIO buffer, B_CACHE is modified according to the backing VM.
3454 * If getblk()ing a previously 0-sized invalid buffer, B_CACHE is set
3455 * and then cleared based on the backing VM. If the previous buffer is
3456 * non-0-sized but invalid, B_CACHE will be cleared.
3458 * If getblk() must create a new buffer, the new buffer is returned with
3459 * both B_INVAL and B_CACHE clear unless it is a VMIO buffer, in which
3460 * case it is returned with B_INVAL clear and B_CACHE set based on the
3463 * getblk() also forces a bwrite() for any B_DELWRI buffer whos
3464 * B_CACHE bit is clear.
3466 * What this means, basically, is that the caller should use B_CACHE to
3467 * determine whether the buffer is fully valid or not and should clear
3468 * B_INVAL prior to issuing a read. If the caller intends to validate
3469 * the buffer by loading its data area with something, the caller needs
3470 * to clear B_INVAL. If the caller does this without issuing an I/O,
3471 * the caller should set B_CACHE ( as an optimization ), else the caller
3472 * should issue the I/O and biodone() will set B_CACHE if the I/O was
3473 * a write attempt or if it was a successful read. If the caller
3474 * intends to issue a READ, the caller must clear B_INVAL and BIO_ERROR
3475 * prior to issuing the READ. biodone() will *not* clear B_INVAL.
3478 getblk(struct vnode *vp, daddr_t blkno, int size, int slpflag, int slptimeo,
3483 int bsize, error, maxsize, vmio;
3486 CTR3(KTR_BUF, "getblk(%p, %ld, %d)", vp, (long)blkno, size);
3487 KASSERT((flags & (GB_UNMAPPED | GB_KVAALLOC)) != GB_KVAALLOC,
3488 ("GB_KVAALLOC only makes sense with GB_UNMAPPED"));
3489 ASSERT_VOP_LOCKED(vp, "getblk");
3490 if (size > MAXBCACHEBUF)
3491 panic("getblk: size(%d) > MAXBCACHEBUF(%d)\n", size,
3493 if (!unmapped_buf_allowed)
3494 flags &= ~(GB_UNMAPPED | GB_KVAALLOC);
3499 bp = gbincore(bo, blkno);
3503 * Buffer is in-core. If the buffer is not busy nor managed,
3504 * it must be on a queue.
3506 lockflags = LK_EXCLUSIVE | LK_SLEEPFAIL | LK_INTERLOCK;
3508 if (flags & GB_LOCK_NOWAIT)
3509 lockflags |= LK_NOWAIT;
3511 error = BUF_TIMELOCK(bp, lockflags,
3512 BO_LOCKPTR(bo), "getblk", slpflag, slptimeo);
3515 * If we slept and got the lock we have to restart in case
3516 * the buffer changed identities.
3518 if (error == ENOLCK)
3520 /* We timed out or were interrupted. */
3523 /* If recursed, assume caller knows the rules. */
3524 else if (BUF_LOCKRECURSED(bp))
3528 * The buffer is locked. B_CACHE is cleared if the buffer is
3529 * invalid. Otherwise, for a non-VMIO buffer, B_CACHE is set
3530 * and for a VMIO buffer B_CACHE is adjusted according to the
3533 if (bp->b_flags & B_INVAL)
3534 bp->b_flags &= ~B_CACHE;
3535 else if ((bp->b_flags & (B_VMIO | B_INVAL)) == 0)
3536 bp->b_flags |= B_CACHE;
3537 if (bp->b_flags & B_MANAGED)
3538 MPASS(bp->b_qindex == QUEUE_NONE);
3543 * check for size inconsistencies for non-VMIO case.
3545 if (bp->b_bcount != size) {
3546 if ((bp->b_flags & B_VMIO) == 0 ||
3547 (size > bp->b_kvasize)) {
3548 if (bp->b_flags & B_DELWRI) {
3550 * If buffer is pinned and caller does
3551 * not want sleep waiting for it to be
3552 * unpinned, bail out
3554 if (bp->b_pin_count > 0) {
3555 if (flags & GB_LOCK_NOWAIT) {
3562 bp->b_flags |= B_NOCACHE;
3565 if (LIST_EMPTY(&bp->b_dep)) {
3566 bp->b_flags |= B_RELBUF;
3569 bp->b_flags |= B_NOCACHE;
3578 * Handle the case of unmapped buffer which should
3579 * become mapped, or the buffer for which KVA
3580 * reservation is requested.
3582 bp_unmapped_get_kva(bp, blkno, size, flags);
3585 * If the size is inconsistent in the VMIO case, we can resize
3586 * the buffer. This might lead to B_CACHE getting set or
3587 * cleared. If the size has not changed, B_CACHE remains
3588 * unchanged from its previous state.
3592 KASSERT(bp->b_offset != NOOFFSET,
3593 ("getblk: no buffer offset"));
3596 * A buffer with B_DELWRI set and B_CACHE clear must
3597 * be committed before we can return the buffer in
3598 * order to prevent the caller from issuing a read
3599 * ( due to B_CACHE not being set ) and overwriting
3602 * Most callers, including NFS and FFS, need this to
3603 * operate properly either because they assume they
3604 * can issue a read if B_CACHE is not set, or because
3605 * ( for example ) an uncached B_DELWRI might loop due
3606 * to softupdates re-dirtying the buffer. In the latter
3607 * case, B_CACHE is set after the first write completes,
3608 * preventing further loops.
3609 * NOTE! b*write() sets B_CACHE. If we cleared B_CACHE
3610 * above while extending the buffer, we cannot allow the
3611 * buffer to remain with B_CACHE set after the write
3612 * completes or it will represent a corrupt state. To
3613 * deal with this we set B_NOCACHE to scrap the buffer
3616 * We might be able to do something fancy, like setting
3617 * B_CACHE in bwrite() except if B_DELWRI is already set,
3618 * so the below call doesn't set B_CACHE, but that gets real
3619 * confusing. This is much easier.
3622 if ((bp->b_flags & (B_CACHE|B_DELWRI)) == B_DELWRI) {
3623 bp->b_flags |= B_NOCACHE;
3627 bp->b_flags &= ~B_DONE;
3630 * Buffer is not in-core, create new buffer. The buffer
3631 * returned by getnewbuf() is locked. Note that the returned
3632 * buffer is also considered valid (not marked B_INVAL).
3636 * If the user does not want us to create the buffer, bail out
3639 if (flags & GB_NOCREAT)
3641 if (numfreebuffers == 0 && TD_IS_IDLETHREAD(curthread))
3644 bsize = vn_isdisk(vp, NULL) ? DEV_BSIZE : bo->bo_bsize;
3645 KASSERT(bsize != 0, ("bsize == 0, check bo->bo_bsize"));
3646 offset = blkno * bsize;
3647 vmio = vp->v_object != NULL;
3649 maxsize = size + (offset & PAGE_MASK);
3652 /* Do not allow non-VMIO notmapped buffers. */
3653 flags &= ~(GB_UNMAPPED | GB_KVAALLOC);
3655 maxsize = imax(maxsize, bsize);
3657 bp = getnewbuf(vp, slpflag, slptimeo, maxsize, flags);
3659 if (slpflag || slptimeo)
3662 * XXX This is here until the sleep path is diagnosed
3663 * enough to work under very low memory conditions.
3665 * There's an issue on low memory, 4BSD+non-preempt
3666 * systems (eg MIPS routers with 32MB RAM) where buffer
3667 * exhaustion occurs without sleeping for buffer
3668 * reclaimation. This just sticks in a loop and
3669 * constantly attempts to allocate a buffer, which
3670 * hits exhaustion and tries to wakeup bufdaemon.
3671 * This never happens because we never yield.
3673 * The real solution is to identify and fix these cases
3674 * so we aren't effectively busy-waiting in a loop
3675 * until the reclaimation path has cycles to run.
3677 kern_yield(PRI_USER);
3682 * This code is used to make sure that a buffer is not
3683 * created while the getnewbuf routine is blocked.
3684 * This can be a problem whether the vnode is locked or not.
3685 * If the buffer is created out from under us, we have to
3686 * throw away the one we just created.
3688 * Note: this must occur before we associate the buffer
3689 * with the vp especially considering limitations in
3690 * the splay tree implementation when dealing with duplicate
3694 if (gbincore(bo, blkno)) {
3696 bp->b_flags |= B_INVAL;
3698 bufspace_release(maxsize);
3703 * Insert the buffer into the hash, so that it can
3704 * be found by incore.
3706 bp->b_blkno = bp->b_lblkno = blkno;
3707 bp->b_offset = offset;
3712 * set B_VMIO bit. allocbuf() the buffer bigger. Since the
3713 * buffer size starts out as 0, B_CACHE will be set by
3714 * allocbuf() for the VMIO case prior to it testing the
3715 * backing store for validity.
3719 bp->b_flags |= B_VMIO;
3720 KASSERT(vp->v_object == bp->b_bufobj->bo_object,
3721 ("ARGH! different b_bufobj->bo_object %p %p %p\n",
3722 bp, vp->v_object, bp->b_bufobj->bo_object));
3724 bp->b_flags &= ~B_VMIO;
3725 KASSERT(bp->b_bufobj->bo_object == NULL,
3726 ("ARGH! has b_bufobj->bo_object %p %p\n",
3727 bp, bp->b_bufobj->bo_object));
3728 BUF_CHECK_MAPPED(bp);
3732 bufspace_release(maxsize);
3733 bp->b_flags &= ~B_DONE;
3735 CTR4(KTR_BUF, "getblk(%p, %ld, %d) = %p", vp, (long)blkno, size, bp);
3736 BUF_ASSERT_HELD(bp);
3738 KASSERT(bp->b_bufobj == bo,
3739 ("bp %p wrong b_bufobj %p should be %p", bp, bp->b_bufobj, bo));
3744 * Get an empty, disassociated buffer of given size. The buffer is initially
3748 geteblk(int size, int flags)
3753 maxsize = (size + BKVAMASK) & ~BKVAMASK;
3754 while ((bp = getnewbuf(NULL, 0, 0, maxsize, flags)) == NULL) {
3755 if ((flags & GB_NOWAIT_BD) &&
3756 (curthread->td_pflags & TDP_BUFNEED) != 0)
3760 bufspace_release(maxsize);
3761 bp->b_flags |= B_INVAL; /* b_dep cleared by getnewbuf() */
3762 BUF_ASSERT_HELD(bp);
3767 * Truncate the backing store for a non-vmio buffer.
3770 vfs_nonvmio_truncate(struct buf *bp, int newbsize)
3773 if (bp->b_flags & B_MALLOC) {
3775 * malloced buffers are not shrunk
3777 if (newbsize == 0) {
3778 bufmallocadjust(bp, 0);
3779 free(bp->b_data, M_BIOBUF);
3780 bp->b_data = bp->b_kvabase;
3781 bp->b_flags &= ~B_MALLOC;
3785 vm_hold_free_pages(bp, newbsize);
3786 bufspace_adjust(bp, newbsize);
3790 * Extend the backing for a non-VMIO buffer.
3793 vfs_nonvmio_extend(struct buf *bp, int newbsize)
3799 * We only use malloced memory on the first allocation.
3800 * and revert to page-allocated memory when the buffer
3803 * There is a potential smp race here that could lead
3804 * to bufmallocspace slightly passing the max. It
3805 * is probably extremely rare and not worth worrying
3808 if (bp->b_bufsize == 0 && newbsize <= PAGE_SIZE/2 &&
3809 bufmallocspace < maxbufmallocspace) {
3810 bp->b_data = malloc(newbsize, M_BIOBUF, M_WAITOK);
3811 bp->b_flags |= B_MALLOC;
3812 bufmallocadjust(bp, newbsize);
3817 * If the buffer is growing on its other-than-first
3818 * allocation then we revert to the page-allocation
3823 if (bp->b_flags & B_MALLOC) {
3824 origbuf = bp->b_data;
3825 origbufsize = bp->b_bufsize;
3826 bp->b_data = bp->b_kvabase;
3827 bufmallocadjust(bp, 0);
3828 bp->b_flags &= ~B_MALLOC;
3829 newbsize = round_page(newbsize);
3831 vm_hold_load_pages(bp, (vm_offset_t) bp->b_data + bp->b_bufsize,
3832 (vm_offset_t) bp->b_data + newbsize);
3833 if (origbuf != NULL) {
3834 bcopy(origbuf, bp->b_data, origbufsize);
3835 free(origbuf, M_BIOBUF);
3837 bufspace_adjust(bp, newbsize);
3841 * This code constitutes the buffer memory from either anonymous system
3842 * memory (in the case of non-VMIO operations) or from an associated
3843 * VM object (in the case of VMIO operations). This code is able to
3844 * resize a buffer up or down.
3846 * Note that this code is tricky, and has many complications to resolve
3847 * deadlock or inconsistent data situations. Tread lightly!!!
3848 * There are B_CACHE and B_DELWRI interactions that must be dealt with by
3849 * the caller. Calling this code willy nilly can result in the loss of data.
3851 * allocbuf() only adjusts B_CACHE for VMIO buffers. getblk() deals with
3852 * B_CACHE for the non-VMIO case.
3855 allocbuf(struct buf *bp, int size)
3859 BUF_ASSERT_HELD(bp);
3861 if (bp->b_bcount == size)
3864 if (bp->b_kvasize != 0 && bp->b_kvasize < size)
3865 panic("allocbuf: buffer too small");
3867 newbsize = roundup2(size, DEV_BSIZE);
3868 if ((bp->b_flags & B_VMIO) == 0) {
3869 if ((bp->b_flags & B_MALLOC) == 0)
3870 newbsize = round_page(newbsize);
3872 * Just get anonymous memory from the kernel. Don't
3873 * mess with B_CACHE.
3875 if (newbsize < bp->b_bufsize)
3876 vfs_nonvmio_truncate(bp, newbsize);
3877 else if (newbsize > bp->b_bufsize)
3878 vfs_nonvmio_extend(bp, newbsize);
3882 desiredpages = (size == 0) ? 0 :
3883 num_pages((bp->b_offset & PAGE_MASK) + newbsize);
3885 if (bp->b_flags & B_MALLOC)
3886 panic("allocbuf: VMIO buffer can't be malloced");
3888 * Set B_CACHE initially if buffer is 0 length or will become
3891 if (size == 0 || bp->b_bufsize == 0)
3892 bp->b_flags |= B_CACHE;
3894 if (newbsize < bp->b_bufsize)
3895 vfs_vmio_truncate(bp, desiredpages);
3896 /* XXX This looks as if it should be newbsize > b_bufsize */
3897 else if (size > bp->b_bcount)
3898 vfs_vmio_extend(bp, desiredpages, size);
3899 bufspace_adjust(bp, newbsize);
3901 bp->b_bcount = size; /* requested buffer size. */
3905 extern int inflight_transient_maps;
3908 biodone(struct bio *bp)
3911 void (*done)(struct bio *);
3912 vm_offset_t start, end;
3914 if ((bp->bio_flags & BIO_TRANSIENT_MAPPING) != 0) {
3915 bp->bio_flags &= ~BIO_TRANSIENT_MAPPING;
3916 bp->bio_flags |= BIO_UNMAPPED;
3917 start = trunc_page((vm_offset_t)bp->bio_data);
3918 end = round_page((vm_offset_t)bp->bio_data + bp->bio_length);
3919 bp->bio_data = unmapped_buf;
3920 pmap_qremove(start, OFF_TO_IDX(end - start));
3921 vmem_free(transient_arena, start, end - start);
3922 atomic_add_int(&inflight_transient_maps, -1);
3924 done = bp->bio_done;
3926 mtxp = mtx_pool_find(mtxpool_sleep, bp);
3928 bp->bio_flags |= BIO_DONE;
3932 bp->bio_flags |= BIO_DONE;
3938 * Wait for a BIO to finish.
3941 biowait(struct bio *bp, const char *wchan)
3945 mtxp = mtx_pool_find(mtxpool_sleep, bp);
3947 while ((bp->bio_flags & BIO_DONE) == 0)
3948 msleep(bp, mtxp, PRIBIO, wchan, 0);
3950 if (bp->bio_error != 0)
3951 return (bp->bio_error);
3952 if (!(bp->bio_flags & BIO_ERROR))
3958 biofinish(struct bio *bp, struct devstat *stat, int error)
3962 bp->bio_error = error;
3963 bp->bio_flags |= BIO_ERROR;
3966 devstat_end_transaction_bio(stat, bp);
3973 * Wait for buffer I/O completion, returning error status. The buffer
3974 * is left locked and B_DONE on return. B_EINTR is converted into an EINTR
3975 * error and cleared.
3978 bufwait(struct buf *bp)
3980 if (bp->b_iocmd == BIO_READ)
3981 bwait(bp, PRIBIO, "biord");
3983 bwait(bp, PRIBIO, "biowr");
3984 if (bp->b_flags & B_EINTR) {
3985 bp->b_flags &= ~B_EINTR;
3988 if (bp->b_ioflags & BIO_ERROR) {
3989 return (bp->b_error ? bp->b_error : EIO);
3998 * Finish I/O on a buffer, optionally calling a completion function.
3999 * This is usually called from an interrupt so process blocking is
4002 * biodone is also responsible for setting B_CACHE in a B_VMIO bp.
4003 * In a non-VMIO bp, B_CACHE will be set on the next getblk()
4004 * assuming B_INVAL is clear.
4006 * For the VMIO case, we set B_CACHE if the op was a read and no
4007 * read error occurred, or if the op was a write. B_CACHE is never
4008 * set if the buffer is invalid or otherwise uncacheable.
4010 * biodone does not mess with B_INVAL, allowing the I/O routine or the
4011 * initiator to leave B_INVAL set to brelse the buffer out of existence
4012 * in the biodone routine.
4015 bufdone(struct buf *bp)
4017 struct bufobj *dropobj;
4018 void (*biodone)(struct buf *);
4020 CTR3(KTR_BUF, "bufdone(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
4023 KASSERT(!(bp->b_flags & B_DONE), ("biodone: bp %p already done", bp));
4024 BUF_ASSERT_HELD(bp);
4026 runningbufwakeup(bp);
4027 if (bp->b_iocmd == BIO_WRITE)
4028 dropobj = bp->b_bufobj;
4029 /* call optional completion function if requested */
4030 if (bp->b_iodone != NULL) {
4031 biodone = bp->b_iodone;
4032 bp->b_iodone = NULL;
4035 bufobj_wdrop(dropobj);
4042 bufobj_wdrop(dropobj);
4046 bufdone_finish(struct buf *bp)
4048 BUF_ASSERT_HELD(bp);
4050 if (!LIST_EMPTY(&bp->b_dep))
4053 if (bp->b_flags & B_VMIO) {
4055 * Set B_CACHE if the op was a normal read and no error
4056 * occurred. B_CACHE is set for writes in the b*write()
4059 if (bp->b_iocmd == BIO_READ &&
4060 !(bp->b_flags & (B_INVAL|B_NOCACHE)) &&
4061 !(bp->b_ioflags & BIO_ERROR))
4062 bp->b_flags |= B_CACHE;
4063 vfs_vmio_iodone(bp);
4067 * For asynchronous completions, release the buffer now. The brelse
4068 * will do a wakeup there if necessary - so no need to do a wakeup
4069 * here in the async case. The sync case always needs to do a wakeup.
4071 if (bp->b_flags & B_ASYNC) {
4072 if ((bp->b_flags & (B_NOCACHE | B_INVAL | B_RELBUF)) ||
4073 (bp->b_ioflags & BIO_ERROR))
4082 * This routine is called in lieu of iodone in the case of
4083 * incomplete I/O. This keeps the busy status for pages
4087 vfs_unbusy_pages(struct buf *bp)
4093 runningbufwakeup(bp);
4094 if (!(bp->b_flags & B_VMIO))
4097 obj = bp->b_bufobj->bo_object;
4098 VM_OBJECT_WLOCK(obj);
4099 for (i = 0; i < bp->b_npages; i++) {
4101 if (m == bogus_page) {
4102 m = vm_page_lookup(obj, OFF_TO_IDX(bp->b_offset) + i);
4104 panic("vfs_unbusy_pages: page missing\n");
4106 if (buf_mapped(bp)) {
4107 BUF_CHECK_MAPPED(bp);
4108 pmap_qenter(trunc_page((vm_offset_t)bp->b_data),
4109 bp->b_pages, bp->b_npages);
4111 BUF_CHECK_UNMAPPED(bp);
4115 vm_object_pip_wakeupn(obj, bp->b_npages);
4116 VM_OBJECT_WUNLOCK(obj);
4120 * vfs_page_set_valid:
4122 * Set the valid bits in a page based on the supplied offset. The
4123 * range is restricted to the buffer's size.
4125 * This routine is typically called after a read completes.
4128 vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, vm_page_t m)
4133 * Compute the end offset, eoff, such that [off, eoff) does not span a
4134 * page boundary and eoff is not greater than the end of the buffer.
4135 * The end of the buffer, in this case, is our file EOF, not the
4136 * allocation size of the buffer.
4138 eoff = (off + PAGE_SIZE) & ~(vm_ooffset_t)PAGE_MASK;
4139 if (eoff > bp->b_offset + bp->b_bcount)
4140 eoff = bp->b_offset + bp->b_bcount;
4143 * Set valid range. This is typically the entire buffer and thus the
4147 vm_page_set_valid_range(m, off & PAGE_MASK, eoff - off);
4151 * vfs_page_set_validclean:
4153 * Set the valid bits and clear the dirty bits in a page based on the
4154 * supplied offset. The range is restricted to the buffer's size.
4157 vfs_page_set_validclean(struct buf *bp, vm_ooffset_t off, vm_page_t m)
4159 vm_ooffset_t soff, eoff;
4162 * Start and end offsets in buffer. eoff - soff may not cross a
4163 * page boundary or cross the end of the buffer. The end of the
4164 * buffer, in this case, is our file EOF, not the allocation size
4168 eoff = (off + PAGE_SIZE) & ~(off_t)PAGE_MASK;
4169 if (eoff > bp->b_offset + bp->b_bcount)
4170 eoff = bp->b_offset + bp->b_bcount;
4173 * Set valid range. This is typically the entire buffer and thus the
4177 vm_page_set_validclean(
4179 (vm_offset_t) (soff & PAGE_MASK),
4180 (vm_offset_t) (eoff - soff)
4186 * Ensure that all buffer pages are not exclusive busied. If any page is
4187 * exclusive busy, drain it.
4190 vfs_drain_busy_pages(struct buf *bp)
4195 VM_OBJECT_ASSERT_WLOCKED(bp->b_bufobj->bo_object);
4197 for (i = 0; i < bp->b_npages; i++) {
4199 if (vm_page_xbusied(m)) {
4200 for (; last_busied < i; last_busied++)
4201 vm_page_sbusy(bp->b_pages[last_busied]);
4202 while (vm_page_xbusied(m)) {
4204 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object);
4205 vm_page_busy_sleep(m, "vbpage");
4206 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object);
4210 for (i = 0; i < last_busied; i++)
4211 vm_page_sunbusy(bp->b_pages[i]);
4215 * This routine is called before a device strategy routine.
4216 * It is used to tell the VM system that paging I/O is in
4217 * progress, and treat the pages associated with the buffer
4218 * almost as being exclusive busy. Also the object paging_in_progress
4219 * flag is handled to make sure that the object doesn't become
4222 * Since I/O has not been initiated yet, certain buffer flags
4223 * such as BIO_ERROR or B_INVAL may be in an inconsistent state
4224 * and should be ignored.
4227 vfs_busy_pages(struct buf *bp, int clear_modify)
4234 if (!(bp->b_flags & B_VMIO))
4237 obj = bp->b_bufobj->bo_object;
4238 foff = bp->b_offset;
4239 KASSERT(bp->b_offset != NOOFFSET,
4240 ("vfs_busy_pages: no buffer offset"));
4241 VM_OBJECT_WLOCK(obj);
4242 vfs_drain_busy_pages(bp);
4243 if (bp->b_bufsize != 0)
4244 vfs_setdirty_locked_object(bp);
4246 for (i = 0; i < bp->b_npages; i++) {
4249 if ((bp->b_flags & B_CLUSTER) == 0) {
4250 vm_object_pip_add(obj, 1);
4254 * When readying a buffer for a read ( i.e
4255 * clear_modify == 0 ), it is important to do
4256 * bogus_page replacement for valid pages in
4257 * partially instantiated buffers. Partially
4258 * instantiated buffers can, in turn, occur when
4259 * reconstituting a buffer from its VM backing store
4260 * base. We only have to do this if B_CACHE is
4261 * clear ( which causes the I/O to occur in the
4262 * first place ). The replacement prevents the read
4263 * I/O from overwriting potentially dirty VM-backed
4264 * pages. XXX bogus page replacement is, uh, bogus.
4265 * It may not work properly with small-block devices.
4266 * We need to find a better way.
4269 pmap_remove_write(m);
4270 vfs_page_set_validclean(bp, foff, m);
4271 } else if (m->valid == VM_PAGE_BITS_ALL &&
4272 (bp->b_flags & B_CACHE) == 0) {
4273 bp->b_pages[i] = bogus_page;
4276 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK;
4278 VM_OBJECT_WUNLOCK(obj);
4279 if (bogus && buf_mapped(bp)) {
4280 BUF_CHECK_MAPPED(bp);
4281 pmap_qenter(trunc_page((vm_offset_t)bp->b_data),
4282 bp->b_pages, bp->b_npages);
4287 * vfs_bio_set_valid:
4289 * Set the range within the buffer to valid. The range is
4290 * relative to the beginning of the buffer, b_offset. Note that
4291 * b_offset itself may be offset from the beginning of the first
4295 vfs_bio_set_valid(struct buf *bp, int base, int size)
4300 if (!(bp->b_flags & B_VMIO))
4304 * Fixup base to be relative to beginning of first page.
4305 * Set initial n to be the maximum number of bytes in the
4306 * first page that can be validated.
4308 base += (bp->b_offset & PAGE_MASK);
4309 n = PAGE_SIZE - (base & PAGE_MASK);
4311 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object);
4312 for (i = base / PAGE_SIZE; size > 0 && i < bp->b_npages; ++i) {
4316 vm_page_set_valid_range(m, base & PAGE_MASK, n);
4321 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object);
4327 * If the specified buffer is a non-VMIO buffer, clear the entire
4328 * buffer. If the specified buffer is a VMIO buffer, clear and
4329 * validate only the previously invalid portions of the buffer.
4330 * This routine essentially fakes an I/O, so we need to clear
4331 * BIO_ERROR and B_INVAL.
4333 * Note that while we only theoretically need to clear through b_bcount,
4334 * we go ahead and clear through b_bufsize.
4337 vfs_bio_clrbuf(struct buf *bp)
4339 int i, j, mask, sa, ea, slide;
4341 if ((bp->b_flags & (B_VMIO | B_MALLOC)) != B_VMIO) {
4345 bp->b_flags &= ~B_INVAL;
4346 bp->b_ioflags &= ~BIO_ERROR;
4347 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object);
4348 if ((bp->b_npages == 1) && (bp->b_bufsize < PAGE_SIZE) &&
4349 (bp->b_offset & PAGE_MASK) == 0) {
4350 if (bp->b_pages[0] == bogus_page)
4352 mask = (1 << (bp->b_bufsize / DEV_BSIZE)) - 1;
4353 VM_OBJECT_ASSERT_WLOCKED(bp->b_pages[0]->object);
4354 if ((bp->b_pages[0]->valid & mask) == mask)
4356 if ((bp->b_pages[0]->valid & mask) == 0) {
4357 pmap_zero_page_area(bp->b_pages[0], 0, bp->b_bufsize);
4358 bp->b_pages[0]->valid |= mask;
4362 sa = bp->b_offset & PAGE_MASK;
4364 for (i = 0; i < bp->b_npages; i++, sa = 0) {
4365 slide = imin(slide + PAGE_SIZE, bp->b_offset + bp->b_bufsize);
4366 ea = slide & PAGE_MASK;
4369 if (bp->b_pages[i] == bogus_page)
4372 mask = ((1 << ((ea - sa) / DEV_BSIZE)) - 1) << j;
4373 VM_OBJECT_ASSERT_WLOCKED(bp->b_pages[i]->object);
4374 if ((bp->b_pages[i]->valid & mask) == mask)
4376 if ((bp->b_pages[i]->valid & mask) == 0)
4377 pmap_zero_page_area(bp->b_pages[i], sa, ea - sa);
4379 for (; sa < ea; sa += DEV_BSIZE, j++) {
4380 if ((bp->b_pages[i]->valid & (1 << j)) == 0) {
4381 pmap_zero_page_area(bp->b_pages[i],
4386 bp->b_pages[i]->valid |= mask;
4389 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object);
4394 vfs_bio_bzero_buf(struct buf *bp, int base, int size)
4399 if (buf_mapped(bp)) {
4400 BUF_CHECK_MAPPED(bp);
4401 bzero(bp->b_data + base, size);
4403 BUF_CHECK_UNMAPPED(bp);
4404 n = PAGE_SIZE - (base & PAGE_MASK);
4405 for (i = base / PAGE_SIZE; size > 0 && i < bp->b_npages; ++i) {
4409 pmap_zero_page_area(m, base & PAGE_MASK, n);
4418 * vm_hold_load_pages and vm_hold_free_pages get pages into
4419 * a buffers address space. The pages are anonymous and are
4420 * not associated with a file object.
4423 vm_hold_load_pages(struct buf *bp, vm_offset_t from, vm_offset_t to)
4429 BUF_CHECK_MAPPED(bp);
4431 to = round_page(to);
4432 from = round_page(from);
4433 index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT;
4435 for (pg = from; pg < to; pg += PAGE_SIZE, index++) {
4438 * note: must allocate system pages since blocking here
4439 * could interfere with paging I/O, no matter which
4442 p = vm_page_alloc(NULL, 0, VM_ALLOC_SYSTEM | VM_ALLOC_NOOBJ |
4443 VM_ALLOC_WIRED | VM_ALLOC_COUNT((to - pg) >> PAGE_SHIFT));
4448 pmap_qenter(pg, &p, 1);
4449 bp->b_pages[index] = p;
4451 bp->b_npages = index;
4454 /* Return pages associated with this buf to the vm system */
4456 vm_hold_free_pages(struct buf *bp, int newbsize)
4460 int index, newnpages;
4462 BUF_CHECK_MAPPED(bp);
4464 from = round_page((vm_offset_t)bp->b_data + newbsize);
4465 newnpages = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT;
4466 if (bp->b_npages > newnpages)
4467 pmap_qremove(from, bp->b_npages - newnpages);
4468 for (index = newnpages; index < bp->b_npages; index++) {
4469 p = bp->b_pages[index];
4470 bp->b_pages[index] = NULL;
4471 if (vm_page_sbusied(p))
4472 printf("vm_hold_free_pages: blkno: %jd, lblkno: %jd\n",
4473 (intmax_t)bp->b_blkno, (intmax_t)bp->b_lblkno);
4476 atomic_subtract_int(&vm_cnt.v_wire_count, 1);
4478 bp->b_npages = newnpages;
4482 * Map an IO request into kernel virtual address space.
4484 * All requests are (re)mapped into kernel VA space.
4485 * Notice that we use b_bufsize for the size of the buffer
4486 * to be mapped. b_bcount might be modified by the driver.
4488 * Note that even if the caller determines that the address space should
4489 * be valid, a race or a smaller-file mapped into a larger space may
4490 * actually cause vmapbuf() to fail, so all callers of vmapbuf() MUST
4491 * check the return value.
4493 * This function only works with pager buffers.
4496 vmapbuf(struct buf *bp, int mapbuf)
4501 if (bp->b_bufsize < 0)
4503 prot = VM_PROT_READ;
4504 if (bp->b_iocmd == BIO_READ)
4505 prot |= VM_PROT_WRITE; /* Less backwards than it looks */
4506 if ((pidx = vm_fault_quick_hold_pages(&curproc->p_vmspace->vm_map,
4507 (vm_offset_t)bp->b_data, bp->b_bufsize, prot, bp->b_pages,
4508 btoc(MAXPHYS))) < 0)
4510 bp->b_npages = pidx;
4511 bp->b_offset = ((vm_offset_t)bp->b_data) & PAGE_MASK;
4512 if (mapbuf || !unmapped_buf_allowed) {
4513 pmap_qenter((vm_offset_t)bp->b_kvabase, bp->b_pages, pidx);
4514 bp->b_data = bp->b_kvabase + bp->b_offset;
4516 bp->b_data = unmapped_buf;
4521 * Free the io map PTEs associated with this IO operation.
4522 * We also invalidate the TLB entries and restore the original b_addr.
4524 * This function only works with pager buffers.
4527 vunmapbuf(struct buf *bp)
4531 npages = bp->b_npages;
4533 pmap_qremove(trunc_page((vm_offset_t)bp->b_data), npages);
4534 vm_page_unhold_pages(bp->b_pages, npages);
4536 bp->b_data = unmapped_buf;
4540 bdone(struct buf *bp)
4544 mtxp = mtx_pool_find(mtxpool_sleep, bp);
4546 bp->b_flags |= B_DONE;
4552 bwait(struct buf *bp, u_char pri, const char *wchan)
4556 mtxp = mtx_pool_find(mtxpool_sleep, bp);
4558 while ((bp->b_flags & B_DONE) == 0)
4559 msleep(bp, mtxp, pri, wchan, 0);
4564 bufsync(struct bufobj *bo, int waitfor)
4567 return (VOP_FSYNC(bo->__bo_vnode, waitfor, curthread));
4571 bufstrategy(struct bufobj *bo, struct buf *bp)
4577 KASSERT(vp == bo->bo_private, ("Inconsistent vnode bufstrategy"));
4578 KASSERT(vp->v_type != VCHR && vp->v_type != VBLK,
4579 ("Wrong vnode in bufstrategy(bp=%p, vp=%p)", bp, vp));
4580 i = VOP_STRATEGY(vp, bp);
4581 KASSERT(i == 0, ("VOP_STRATEGY failed bp=%p vp=%p", bp, bp->b_vp));
4585 bufobj_wrefl(struct bufobj *bo)
4588 KASSERT(bo != NULL, ("NULL bo in bufobj_wref"));
4589 ASSERT_BO_WLOCKED(bo);
4594 bufobj_wref(struct bufobj *bo)
4597 KASSERT(bo != NULL, ("NULL bo in bufobj_wref"));
4604 bufobj_wdrop(struct bufobj *bo)
4607 KASSERT(bo != NULL, ("NULL bo in bufobj_wdrop"));
4609 KASSERT(bo->bo_numoutput > 0, ("bufobj_wdrop non-positive count"));
4610 if ((--bo->bo_numoutput == 0) && (bo->bo_flag & BO_WWAIT)) {
4611 bo->bo_flag &= ~BO_WWAIT;
4612 wakeup(&bo->bo_numoutput);
4618 bufobj_wwait(struct bufobj *bo, int slpflag, int timeo)
4622 KASSERT(bo != NULL, ("NULL bo in bufobj_wwait"));
4623 ASSERT_BO_WLOCKED(bo);
4625 while (bo->bo_numoutput) {
4626 bo->bo_flag |= BO_WWAIT;
4627 error = msleep(&bo->bo_numoutput, BO_LOCKPTR(bo),
4628 slpflag | (PRIBIO + 1), "bo_wwait", timeo);
4636 bpin(struct buf *bp)
4640 mtxp = mtx_pool_find(mtxpool_sleep, bp);
4647 bunpin(struct buf *bp)
4651 mtxp = mtx_pool_find(mtxpool_sleep, bp);
4653 if (--bp->b_pin_count == 0)
4659 bunpin_wait(struct buf *bp)
4663 mtxp = mtx_pool_find(mtxpool_sleep, bp);
4665 while (bp->b_pin_count > 0)
4666 msleep(bp, mtxp, PRIBIO, "bwunpin", 0);
4671 * Set bio_data or bio_ma for struct bio from the struct buf.
4674 bdata2bio(struct buf *bp, struct bio *bip)
4677 if (!buf_mapped(bp)) {
4678 KASSERT(unmapped_buf_allowed, ("unmapped"));
4679 bip->bio_ma = bp->b_pages;
4680 bip->bio_ma_n = bp->b_npages;
4681 bip->bio_data = unmapped_buf;
4682 bip->bio_ma_offset = (vm_offset_t)bp->b_offset & PAGE_MASK;
4683 bip->bio_flags |= BIO_UNMAPPED;
4684 KASSERT(round_page(bip->bio_ma_offset + bip->bio_length) /
4685 PAGE_SIZE == bp->b_npages,
4686 ("Buffer %p too short: %d %lld %d", bp, bip->bio_ma_offset,
4687 (long long)bip->bio_length, bip->bio_ma_n));
4689 bip->bio_data = bp->b_data;
4694 #include "opt_ddb.h"
4696 #include <ddb/ddb.h>
4698 /* DDB command to show buffer data */
4699 DB_SHOW_COMMAND(buffer, db_show_buffer)
4702 struct buf *bp = (struct buf *)addr;
4705 db_printf("usage: show buffer <addr>\n");
4709 db_printf("buf at %p\n", bp);
4710 db_printf("b_flags = 0x%b, b_xflags=0x%b, b_vflags=0x%b\n",
4711 (u_int)bp->b_flags, PRINT_BUF_FLAGS, (u_int)bp->b_xflags,
4712 PRINT_BUF_XFLAGS, (u_int)bp->b_vflags, PRINT_BUF_VFLAGS);
4714 "b_error = %d, b_bufsize = %ld, b_bcount = %ld, b_resid = %ld\n"
4715 "b_bufobj = (%p), b_data = %p, b_blkno = %jd, b_lblkno = %jd, "
4717 bp->b_error, bp->b_bufsize, bp->b_bcount, bp->b_resid,
4718 bp->b_bufobj, bp->b_data, (intmax_t)bp->b_blkno,
4719 (intmax_t)bp->b_lblkno, bp->b_dep.lh_first);
4720 db_printf("b_kvabase = %p, b_kvasize = %d\n",
4721 bp->b_kvabase, bp->b_kvasize);
4724 db_printf("b_npages = %d, pages(OBJ, IDX, PA): ", bp->b_npages);
4725 for (i = 0; i < bp->b_npages; i++) {
4728 db_printf("(%p, 0x%lx, 0x%lx)", (void *)m->object,
4729 (u_long)m->pindex, (u_long)VM_PAGE_TO_PHYS(m));
4730 if ((i + 1) < bp->b_npages)
4736 BUF_LOCKPRINTINFO(bp);
4739 DB_SHOW_COMMAND(lockedbufs, lockedbufs)
4744 for (i = 0; i < nbuf; i++) {
4746 if (BUF_ISLOCKED(bp)) {
4747 db_show_buffer((uintptr_t)bp, 1, 0, NULL);
4753 DB_SHOW_COMMAND(vnodebufs, db_show_vnodebufs)
4759 db_printf("usage: show vnodebufs <addr>\n");
4762 vp = (struct vnode *)addr;
4763 db_printf("Clean buffers:\n");
4764 TAILQ_FOREACH(bp, &vp->v_bufobj.bo_clean.bv_hd, b_bobufs) {
4765 db_show_buffer((uintptr_t)bp, 1, 0, NULL);
4768 db_printf("Dirty buffers:\n");
4769 TAILQ_FOREACH(bp, &vp->v_bufobj.bo_dirty.bv_hd, b_bobufs) {
4770 db_show_buffer((uintptr_t)bp, 1, 0, NULL);
4775 DB_COMMAND(countfreebufs, db_coundfreebufs)
4778 int i, used = 0, nfree = 0;
4781 db_printf("usage: countfreebufs\n");
4785 for (i = 0; i < nbuf; i++) {
4787 if (bp->b_qindex == QUEUE_EMPTY)
4793 db_printf("Counted %d free, %d used (%d tot)\n", nfree, used,
4795 db_printf("numfreebuffers is %d\n", numfreebuffers);