root/kern/vfs_bio.c

DEFINITIONS

1. size2cqueue
2. bremfree
3. buf_init
4. buf_stub
5. buf_get
6. buf_put
7. bufinit
8. bio_doread
9. bread
10. breadn
11. bread_cluster_callback
12. bread_cluster
13. bwrite
14. bdwrite
15. bawrite
16. buf_dirty
17. buf_undirty
18. brelse
19. incore
20. getblk
21. geteblk
22. getnewbuf
23. buf_daemon
24. biowait
25. biodone
26. vfs_bufstats
27. vfs_bufstats

    1 /*      $OpenBSD: vfs_bio.c,v 1.99 2007/08/07 04:32:45 beck Exp $       */
    2 /*      $NetBSD: vfs_bio.c,v 1.44 1996/06/11 11:15:36 pk Exp $  */
    4 /*-
    5  * Copyright (c) 1994 Christopher G. Demetriou
    6  * Copyright (c) 1982, 1986, 1989, 1993
    7  *      The Regents of the University of California.  All rights reserved.
    8  * (c) UNIX System Laboratories, Inc.
    9  * All or some portions of this file are derived from material licensed
   10  * to the University of California by American Telephone and Telegraph
   11  * Co. or Unix System Laboratories, Inc. and are reproduced herein with
   12  * the permission of UNIX System Laboratories, Inc.
   13  *
   14  * Redistribution and use in source and binary forms, with or without
   15  * modification, are permitted provided that the following conditions
   16  * are met:
   17  * 1. Redistributions of source code must retain the above copyright
   18  *    notice, this list of conditions and the following disclaimer.
   19  * 2. Redistributions in binary form must reproduce the above copyright
   20  *    notice, this list of conditions and the following disclaimer in the
   21  *    documentation and/or other materials provided with the distribution.
   22  * 3. Neither the name of the University nor the names of its contributors
   23  *    may be used to endorse or promote products derived from this software
   24  *    without specific prior written permission.
   25  *
   26  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
   27  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   28  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   29  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
   30  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   31  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   32  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   33  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   34  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   35  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   36  * SUCH DAMAGE.
   37  *
   38  *      @(#)vfs_bio.c   8.6 (Berkeley) 1/11/94
   39  */
   41 /*
   42  * Some references:
   43  *      Bach: The Design of the UNIX Operating System (Prentice Hall, 1986)
   44  *      Leffler, et al.: The Design and Implementation of the 4.3BSD
   45  *              UNIX Operating System (Addison Welley, 1989)
   46  */
   48 #include <sys/param.h>
   49 #include <sys/systm.h>
   50 #include <sys/proc.h>
   51 #include <sys/buf.h>
   52 #include <sys/vnode.h>
   53 #include <sys/mount.h>
   54 #include <sys/malloc.h>
   55 #include <sys/pool.h>
   56 #include <sys/resourcevar.h>
   57 #include <sys/conf.h>
   58 #include <sys/kernel.h>
   60 #include <uvm/uvm_extern.h>
   62 #include <miscfs/specfs/specdev.h>
   64 /*
   65  * Definitions for the buffer hash lists.
   66  */
   67 #define BUFHASH(dvp, lbn)       \
   68         (&bufhashtbl[((long)(dvp) / sizeof(*(dvp)) + (int)(lbn)) & bufhash])
LIST_HEAD(bufhashhdr, buf) *bufhashtbl, invalhash;
u_long  bufhash;
   72 /*
   73  * Insq/Remq for the buffer hash lists.
   74  */
   75 #define binshash(bp, dp)        LIST_INSERT_HEAD(dp, bp, b_hash)
   76 #define bremhash(bp)            LIST_REMOVE(bp, b_hash)
   78 /*
   79  * Definitions for the buffer free lists.
   80  */
   81 #define BQUEUES         6               /* number of free buffer queues */
   83 #define BQ_DIRTY        0               /* LRU queue with dirty buffers */
TAILQ_HEAD(bqueues, buf) bufqueues[BQUEUES];
   87 int bqpages[BQUEUES];           /* pages allocated, per queue */
   88 int bqpagelow;
   89 int needbuffer;
   90 struct bio_ops bioops;
   92 /*
   93  * Buffer pool for I/O buffers.
   94  */
   95 struct pool bufpool;
   96 struct vm_map *buf_map;
   97 struct bufhead bufhead = LIST_HEAD_INITIALIZER(bufhead);
   98 struct buf *buf_get(size_t);
   99 struct buf *buf_stub(struct vnode *, daddr64_t);
  100 void buf_put(struct buf *);
  102 /*
  103  * Insq/Remq for the buffer free lists.
  104  */
  105 #define binsheadfree(bp, dp)    TAILQ_INSERT_HEAD(dp, bp, b_freelist)
  106 #define binstailfree(bp, dp)    TAILQ_INSERT_TAIL(dp, bp, b_freelist)
  108 struct buf *bio_doread(struct vnode *, daddr64_t, int, int);
  109 struct buf *getnewbuf(size_t, int, int, int *);
  110 void buf_init(struct buf *, int);
  111 void bread_cluster_callback(struct buf *);
  113 /*
  114  * We keep a few counters to monitor the utilization of the buffer cache
  115  *
  116  *  numbufpages   - number of pages totally allocated.
  117  *  numdirtypages - number of pages on BQ_DIRTY queue.
  118  *  lodirtypages  - low water mark for buffer cleaning daemon.
  119  *  hidirtypages  - high water mark for buffer cleaning daemon.
  120  *  numfreepages  - number of pages on BQ_CLEAN and BQ_DIRTY queues. unused.
  121  *  numcleanpages - number of pages on BQ_CLEAN queue.
  122  *                  Used to track the need to speedup the cleaner and 
  123  *                  as a reserve for special processes like syncer.
  124  *  maxcleanpages - the highest page count on BQ_CLEAN.
  125  */
  126 long numbufpages;
  127 long numdirtypages;
  128 long lodirtypages;
  129 long hidirtypages;
  130 long numfreepages;
  131 long numcleanpages;
  132 long locleanpages;
  133 long hicleanpages;
  134 long maxcleanpages;
  136 struct proc *cleanerproc;
  137 int bd_req;                     /* Sleep point for cleaner daemon. */
  139 int size2cqueue(int *size);
  141 int
size2cqueue(int *size)
  143 {
  144         int i = 0, q;
  145         int s = *size;
s -= 1;
  147         while (s > 0) {
s = s >> 1;
i++;
  150         }
  151         if (i < PAGE_SHIFT) {
i = PAGE_SHIFT; /* < 4096 -> 4096 */
  153         }
  154         *size = 1 << i;
q = (i + 1 - PAGE_SHIFT); /* XXX 4096 is queue 1 */
  156         if (q >= BQUEUES)
panic("queue %d > BQUEUES %d", q, BQUEUES);
  158         if (q == 0)
panic("can't return dirty q");
  160         return(q);
  161 }
  163 void
bremfree(struct buf *bp)
  165 {
  166         struct bqueues *dp = NULL;
  167         int queue;
  169         /*
  170          * We only calculate the head of the freelist when removing
  171          * the last element of the list as that is the only time that
  172          * it is needed (e.g. to reset the tail pointer).
  173          *
  174          * NB: This makes an assumption about how tailq's are implemented.
  175          */
  176         if (TAILQ_NEXT(bp, b_freelist) == NULL) {
  177                 for (dp = bufqueues; dp < &bufqueues[BQUEUES]; dp++)
  178                         if (dp->tqh_last == &TAILQ_NEXT(bp, b_freelist))
  179                                 break;
  180                 if (dp == &bufqueues[BQUEUES])
panic("bremfree: lost tail");
  182         }
numfreepages -= btoc(bp->b_bufsize);
  184         if (!ISSET(bp->b_flags, B_DELWRI)) {
  185                 int qs = bp->b_bufsize;
queue = size2cqueue(&qs);
numcleanpages -= btoc(bp->b_bufsize);
bqpages[queue] -= btoc(bp->b_bufsize);
  189         } else
numdirtypages -= btoc(bp->b_bufsize);
TAILQ_REMOVE(dp, bp, b_freelist);
  192 }
  194 void
buf_init(struct buf *bp, int size)
  196 {
  197         int npages, queue;
splassert(IPL_BIO);
npages = btoc(size);
bzero((char *)bp, sizeof *bp);
bp->b_vnbufs.le_next = NOLIST;
bp->b_freelist.tqe_next = NOLIST;
bp->b_synctime = time_uptime + 300;
bp->b_dev = NODEV;
queue = size2cqueue(&size);
LIST_INIT(&bp->b_dep);
numbufpages += npages;
numfreepages += npages;
numcleanpages += npages;
bqpages[queue] += npages;
  213         if (maxcleanpages < numcleanpages)
maxcleanpages = numcleanpages;
  215 }
  217 /*
  218  * This is a non-sleeping expanded equivalent of getblk() that allocates only
  219  * the buffer structure, and not its contents.
  220  */
  221 struct buf *
buf_stub(struct vnode *vp, daddr64_t lblkno)
  223 {
  224         struct buf *bp;
  225         int s;
s = splbio();
bp = pool_get(&bufpool, PR_NOWAIT);
splx(s);
  231         if (bp == NULL)
  232                 return (NULL);
bzero((char *)bp, sizeof *bp);
bp->b_vnbufs.le_next = NOLIST;
bp->b_freelist.tqe_next = NOLIST;
bp->b_synctime = time_uptime + 300;
bp->b_dev = NODEV;
bp->b_bufsize = 0;
bp->b_data = NULL;
bp->b_flags = B_BUSY;
bp->b_dev = NODEV;
bp->b_blkno = bp->b_lblkno = lblkno;
bp->b_iodone = NULL;
bp->b_error = 0;
bp->b_resid = 0;
bp->b_bcount = 0;
bp->b_dirtyoff = bp->b_dirtyend = 0;
bp->b_validoff = bp->b_validend = 0;
LIST_INIT(&bp->b_dep);
s = splbio();
LIST_INSERT_HEAD(&bufhead, bp, b_list);
bgetvp(vp, bp);
splx(s);
  258         return (bp);
  259 }
  261 struct buf *
buf_get(size_t size)
  263 {
  264         struct bqueues *dp;
  265         struct buf *bp;
  266         int npages;
  267         int queue, qs;
  268         void *data;
splassert(IPL_BIO);
KASSERT(size > 0);
size = round_page(size);
qs = size;
queue = size2cqueue(&qs);
npages = btoc(qs);
  279         if (numbufpages + npages > bufpages)
  280                 return (NULL);
bp = pool_get(&bufpool, PR_WAITOK);
data = (void *)uvm_km_alloc(buf_map, qs);
  285         if (data == NULL) {
pool_put(&bufpool, bp);
  287                 return (NULL);
  288         }
buf_init(bp, qs);
bp->b_flags = B_INVAL;
bp->b_bufsize = qs;
bp->b_data = data;
dp = &bufqueues[queue];
binsheadfree(bp, dp);
binshash(bp, &invalhash);
LIST_INSERT_HEAD(&bufhead, bp, b_list);
  298         return (bp);
  299 }
  301 void
buf_put(struct buf *bp)
  303 {
splassert(IPL_BIO);
  305 #ifdef DIAGNOSTIC
  306         if (bp->b_data != NULL)
KASSERT(bp->b_bufsize > 0);
  308 #endif
  309 #ifdef QUEUE_MACRO_DEBUG
  310         if (bp->b_freelist.tqe_next != NOLIST &&
bp->b_freelist.tqe_next != (void *)-1)
panic("buf_put: still on the free list");
  314         if (bp->b_vnbufs.le_next != NOLIST &&
bp->b_vnbufs.le_next != (void *)-1)
panic("buf_put: still on the vnode list");
  317 #endif
  318 #ifdef DIAGNOSTIC
  319         if (!LIST_EMPTY(&bp->b_dep))
panic("buf_put: b_dep is not empty");
  321 #endif
LIST_REMOVE(bp, b_list);
  324         if (bp->b_data != NULL) {
bremhash(bp);
numbufpages -= btoc(bp->b_bufsize);
uvm_km_free(buf_map, (vaddr_t)bp->b_data, bp->b_bufsize);
  328         }
pool_put(&bufpool, bp);
  331 }
  333 /*
  334  * Initialize buffers and hash links for buffers.
  335  */
  336 void
bufinit(void)
  338 {
vaddr_t minaddr, maxaddr;
  340         struct bqueues *dp;
pool_init(&bufpool, sizeof(struct buf), 0, 0, 0, "bufpl", NULL);
pool_setipl(&bufpool, IPL_BIO);
  344         for (dp = bufqueues; dp < &bufqueues[BQUEUES]; dp++)
TAILQ_INIT(dp);
minaddr = vm_map_min(kernel_map);
buf_map = uvm_km_suballoc(kernel_map, &minaddr, &maxaddr,
ptoa(bufpages), 0, FALSE, NULL);
  350         /* 
  351          * XXX don't starve any one queue below 5% of the total number
  352          * of buffer cache pages.
  353          */
bqpagelow = bufpages / 20; 
bufhashtbl = hashinit(bufpages / 4, M_CACHE, M_WAITOK, &bufhash);
hidirtypages = (bufpages / 4) * 3;
lodirtypages = bufpages / 2;
  360         /*
  361          * Reserve 5% of bufpages for syncer's needs,
  362          * but not more than 25% and if possible
  363          * not less than 2 * MAXBSIZE. locleanpages
  364          * value must be not too small
  365          */
hicleanpages = bufpages / 2;
locleanpages = hicleanpages / 2;
  368         if (locleanpages < btoc(2 * MAXBSIZE))
locleanpages = btoc(2 * MAXBSIZE);
  370         if (locleanpages > bufpages / 4)
locleanpages = bufpages / 4;
maxcleanpages = locleanpages;
  374 }
  376 struct buf *
bio_doread(struct vnode *vp, daddr64_t blkno, int size, int async)
  378 {
  379         struct buf *bp;
bp = getblk(vp, blkno, size, 0, 0);
  383         /*
  384          * If buffer does not have valid data, start a read.
  385          * Note that if buffer is B_INVAL, getblk() won't return it.
  386          * Therefore, it's valid if its I/O has completed or been delayed.
  387          */
  388         if (!ISSET(bp->b_flags, (B_DONE | B_DELWRI))) {
SET(bp->b_flags, B_READ | async);
VOP_STRATEGY(bp);
  392                 /* Pay for the read. */
curproc->p_stats->p_ru.ru_inblock++;            /* XXX */
  394         } else if (async) {
brelse(bp);
  396         }
  398         return (bp);
  399 }
  401 /*
  402  * Read a disk block.
  403  * This algorithm described in Bach (p.54).
  404  */
  405 int
bread(struct vnode *vp, daddr64_t blkno, int size, struct ucred *cred,
  407     struct buf **bpp)
  408 {
  409         struct buf *bp;
  411         /* Get buffer for block. */
bp = *bpp = bio_doread(vp, blkno, size, 0);
  414         /* Wait for the read to complete, and return result. */
  415         return (biowait(bp));
  416 }
  418 /*
  419  * Read-ahead multiple disk blocks. The first is sync, the rest async.
  420  * Trivial modification to the breada algorithm presented in Bach (p.55).
  421  */
  422 int
breadn(struct vnode *vp, daddr64_t blkno, int size, daddr64_t rablks[],
  424     int rasizes[], int nrablks, struct ucred *cred, struct buf **bpp)
  425 {
  426         struct buf *bp;
  427         int i;
bp = *bpp = bio_doread(vp, blkno, size, 0);
  431         /*
  432          * For each of the read-ahead blocks, start a read, if necessary.
  433          */
  434         for (i = 0; i < nrablks; i++) {
  435                 /* If it's in the cache, just go on to next one. */
  436                 if (incore(vp, rablks[i]))
  437                         continue;
  439                 /* Get a buffer for the read-ahead block */
  440                 (void) bio_doread(vp, rablks[i], rasizes[i], B_ASYNC);
  441         }
  443         /* Otherwise, we had to start a read for it; wait until it's valid. */
  444         return (biowait(bp));
  445 }
  447 /*
  448  * Called from interrupt context.
  449  */
  450 void
bread_cluster_callback(struct buf *bp)
  452 {
  453         int i;
  454         struct buf **xbpp;
xbpp = (struct buf **)bp->b_saveaddr;
  458         for (i = 0; xbpp[i] != 0; i++) {
  459                 if (ISSET(bp->b_flags, B_ERROR))
SET(xbpp[i]->b_flags, B_INVAL | B_ERROR);
biodone(xbpp[i]);
  462         }
free(xbpp, M_TEMP);
bp->b_data = NULL;
buf_put(bp);
  467 }
  469 int
bread_cluster(struct vnode *vp, daddr64_t blkno, int size, struct buf **rbpp)
  471 {
  472         struct buf *bp, **xbpp;
  473         int howmany, i, maxra, inc;
daddr64_t sblkno;
size_t spill;
  477         *rbpp = bio_doread(vp, blkno, size, 0);
  479         if (size != round_page(size))
  480                 return (biowait(*rbpp));
  482         if (VOP_BMAP(vp, blkno + 1, NULL, &sblkno, &maxra))
  483                 return (biowait(*rbpp));
maxra++; 
  486         if (sblkno == -1 || maxra < 2)
  487                 return (biowait(*rbpp));
howmany = MAXPHYS / size;
  490         if (howmany > maxra)
howmany = maxra;
xbpp = malloc((howmany + 1) * sizeof(struct buf *), M_TEMP, M_NOWAIT);
  494         if (xbpp == NULL)
  495                 return (biowait(*rbpp));
  497         for (i = 0; i < howmany; i++) {
  498                 if (incore(vp, blkno + i + 1)) {
  499                         for (--i; i >= 0; i--) {
SET(xbpp[i]->b_flags, B_INVAL);
brelse(xbpp[i]);
  502                         }
free(xbpp, M_TEMP);
  504                         return (biowait(*rbpp));
  505                 }
xbpp[i] = buf_stub(vp, blkno + i + 1);
  507                 if (xbpp[i] == NULL) {
  508                         for (--i; i >= 0; i--) {
SET(xbpp[i]->b_flags, B_INVAL);
brelse(xbpp[i]);
  511                         }
free(xbpp, M_TEMP);
  513                         return (biowait(*rbpp));
  514                 }
  515         }
xbpp[howmany] = 0;
bp = getnewbuf(howmany * size, 0, 0, NULL);
  520         if (bp == NULL) {
  521                 for (i = 0; i < howmany; i++) {
SET(xbpp[i]->b_flags, B_INVAL);
brelse(xbpp[i]);
  524                 }
free(xbpp, M_TEMP);
  526                 return (biowait(*rbpp));
  527         }
inc = btodb(size);
  531         for (i = 0; i < howmany; i++) {
SET(xbpp[i]->b_flags, B_READ | B_ASYNC);
binshash(xbpp[i], BUFHASH(vp, xbpp[i]->b_lblkno));
xbpp[i]->b_blkno = sblkno + (i * inc);
xbpp[i]->b_bufsize = xbpp[i]->b_bcount = size;
xbpp[i]->b_data = bp->b_data + (i * size);
  537         }
bp->b_blkno = sblkno;
bp->b_lblkno = blkno + 1;
SET(bp->b_flags, B_READ | B_ASYNC | B_CALL);
bp->b_saveaddr = (void *)xbpp;
bp->b_iodone = bread_cluster_callback;
bp->b_vp = vp;
spill = bp->b_bufsize - bp->b_bcount;
  546         if (spill) {
uvm_km_free(buf_map, (vaddr_t) bp->b_data + bp->b_bcount,
spill);
numbufpages -= atop(spill);
  550         }
VOP_STRATEGY(bp);
curproc->p_stats->p_ru.ru_inblock++;
  554         return (biowait(*rbpp));
  555 }
  557 /*
  558  * Block write.  Described in Bach (p.56)
  559  */
  560 int
bwrite(struct buf *bp)
  562 {
  563         int rv, async, wasdelayed, s;
  564         struct vnode *vp;
  565         struct mount *mp;
vp = bp->b_vp;
  568         if (vp != NULL)
mp = vp->v_type == VBLK? vp->v_specmountpoint : vp->v_mount;
  570         else
mp = NULL;
  573         /*
  574          * Remember buffer type, to switch on it later.  If the write was
  575          * synchronous, but the file system was mounted with MNT_ASYNC,
  576          * convert it to a delayed write.
  577          * XXX note that this relies on delayed tape writes being converted
  578          * to async, not sync writes (which is safe, but ugly).
  579          */
async = ISSET(bp->b_flags, B_ASYNC);
  581         if (!async && mp && ISSET(mp->mnt_flag, MNT_ASYNC)) {
bdwrite(bp);
  583                 return (0);
  584         }
  586         /*
  587          * Collect statistics on synchronous and asynchronous writes.
  588          * Writes to block devices are charged to their associated
  589          * filesystem (if any).
  590          */
  591         if (mp != NULL) {
  592                 if (async)
mp->mnt_stat.f_asyncwrites++;
  594                 else
mp->mnt_stat.f_syncwrites++;
  596         }
wasdelayed = ISSET(bp->b_flags, B_DELWRI);
CLR(bp->b_flags, (B_READ | B_DONE | B_ERROR | B_DELWRI));
s = splbio();
  603         /*
  604          * If not synchronous, pay for the I/O operation and make
  605          * sure the buf is on the correct vnode queue.  We have
  606          * to do this now, because if we don't, the vnode may not
  607          * be properly notified that its I/O has completed.
  608          */
  609         if (wasdelayed) {
reassignbuf(bp);
  611         } else
curproc->p_stats->p_ru.ru_oublock++;
  615         /* Initiate disk write.  Make sure the appropriate party is charged. */
bp->b_vp->v_numoutput++;
splx(s);
SET(bp->b_flags, B_WRITEINPROG);
VOP_STRATEGY(bp);
  621         if (async)
  622                 return (0);
  624         /*
  625          * If I/O was synchronous, wait for it to complete.
  626          */
rv = biowait(bp);
  629         /* Release the buffer. */
brelse(bp);
  632         return (rv);
  633 }
  636 /*
  637  * Delayed write.
  638  *
  639  * The buffer is marked dirty, but is not queued for I/O.
  640  * This routine should be used when the buffer is expected
  641  * to be modified again soon, typically a small write that
  642  * partially fills a buffer.
  643  *
  644  * NB: magnetic tapes cannot be delayed; they must be
  645  * written in the order that the writes are requested.
  646  *
  647  * Described in Leffler, et al. (pp. 208-213).
  648  */
  649 void
bdwrite(struct buf *bp)
  651 {
  652         int s;
  654         /*
  655          * If the block hasn't been seen before:
  656          *      (1) Mark it as having been seen,
  657          *      (2) Charge for the write.
  658          *      (3) Make sure it's on its vnode's correct block list,
  659          *      (4) If a buffer is rewritten, move it to end of dirty list
  660          */
  661         if (!ISSET(bp->b_flags, B_DELWRI)) {
SET(bp->b_flags, B_DELWRI);
bp->b_synctime = time_uptime + 35;
s = splbio();
reassignbuf(bp);
splx(s);
curproc->p_stats->p_ru.ru_oublock++;    /* XXX */
  668         } else {
  669                 /*
  670                  * see if this buffer has slacked through the syncer
  671                  * and enforce an async write upon it.
  672                  */
  673                 if (bp->b_synctime < time_uptime) {
bawrite(bp);
  675                         return;
  676                 }
  677         }
  679         /* If this is a tape block, write the block now. */
  680         if (major(bp->b_dev) < nblkdev &&
bdevsw[major(bp->b_dev)].d_type == D_TAPE) {
bawrite(bp);
  683                 return;
  684         }
  686         /* Otherwise, the "write" is done, so mark and release the buffer. */
CLR(bp->b_flags, B_NEEDCOMMIT);
SET(bp->b_flags, B_DONE);
brelse(bp);
  690 }
  692 /*
  693  * Asynchronous block write; just an asynchronous bwrite().
  694  */
  695 void
bawrite(struct buf *bp)
  697 {
SET(bp->b_flags, B_ASYNC);
VOP_BWRITE(bp);
  701 }
  703 /*
  704  * Must be called at splbio()
  705  */
  706 void
buf_dirty(struct buf *bp)
  708 {
splassert(IPL_BIO);
  711         if (ISSET(bp->b_flags, B_DELWRI) == 0) {
SET(bp->b_flags, B_DELWRI);
bp->b_synctime = time_uptime + 35;
reassignbuf(bp);
  715         }
  716 }
  718 /*
  719  * Must be called at splbio()
  720  */
  721 void
buf_undirty(struct buf *bp)
  723 {
splassert(IPL_BIO);
  726         if (ISSET(bp->b_flags, B_DELWRI)) {
CLR(bp->b_flags, B_DELWRI);
reassignbuf(bp);
  729         }
  730 }
  732 /*
  733  * Release a buffer on to the free lists.
  734  * Described in Bach (p. 46).
  735  */
  736 void
brelse(struct buf *bp)
  738 {
  739         struct bqueues *bufq;
  740         int s;
  742         /* Block disk interrupts. */
s = splbio();
  745         if (bp->b_data != NULL)
KASSERT(bp->b_bufsize > 0);
  748         /*
  749          * Determine which queue the buffer should be on, then put it there.
  750          */
  752         /* If it's not cacheable, or an error, mark it invalid. */
  753         if (ISSET(bp->b_flags, (B_NOCACHE|B_ERROR)))
SET(bp->b_flags, B_INVAL);
  756         if (ISSET(bp->b_flags, B_INVAL)) {
  757                 int queue, qs;
  759                 /*
  760                  * If the buffer is invalid, place it in the clean queue, so it
  761                  * can be reused.
  762                  */
  763                 if (LIST_FIRST(&bp->b_dep) != NULL)
buf_deallocate(bp);
  766                 if (ISSET(bp->b_flags, B_DELWRI)) {
CLR(bp->b_flags, B_DELWRI);
  768                 }
  770                 if (bp->b_vp)
brelvp(bp);
  773                 /*
  774                  * If the buffer has no associated data, place it back in the
  775                  * pool.
  776                  */
  777                 if (bp->b_data == NULL) {
buf_put(bp);
splx(s);
  780                         return;
  781                 }
qs = bp->b_bufsize;
queue = size2cqueue(&qs);
numcleanpages += btoc(bp->b_bufsize);
bqpages[queue] += btoc(bp->b_bufsize);
  787                 if (maxcleanpages < numcleanpages)
maxcleanpages = numcleanpages;
binsheadfree(bp, &bufqueues[queue]);
  790         } else {
  791                 /*
  792                  * It has valid data.  Put it on the end of the appropriate
  793                  * queue, so that it'll stick around for as long as possible.
  794                  */
  795                 int queue, qs;
numfreepages += btoc(bp->b_bufsize);
qs = bp->b_bufsize;
queue = size2cqueue(&qs);
  800                 if (!ISSET(bp->b_flags, B_DELWRI)) {
numcleanpages += btoc(bp->b_bufsize);
bqpages[queue] += btoc(bp->b_bufsize);
  803                         if (maxcleanpages < numcleanpages)
maxcleanpages = numcleanpages;
bufq = &bufqueues[queue];
  806                 } else {
numdirtypages += btoc(bp->b_bufsize);
bufq = &bufqueues[BQ_DIRTY];
  809                 }
  810                 if (ISSET(bp->b_flags, B_AGE)) {
binsheadfree(bp, bufq);
bp->b_synctime = time_uptime + 30;
  813                 } else {
binstailfree(bp, bufq);
bp->b_synctime = time_uptime + 300;
  816                 }
  817         }
  819         /* Unlock the buffer. */
CLR(bp->b_flags, (B_AGE | B_ASYNC | B_BUSY | B_NOCACHE | B_DEFERRED));
  822         /* Wake up any processes waiting for any buffer to become free. */
  823         if (needbuffer) {
needbuffer--;
wakeup_one(&needbuffer);
  826         }
  828         /* Wake up any processes waiting for _this_ buffer to become free. */
  829         if (ISSET(bp->b_flags, B_WANTED)) {
CLR(bp->b_flags, B_WANTED);
wakeup(bp);
  832         }
splx(s);
  835 }
  837 /*
  838  * Determine if a block is in the cache. Just look on what would be its hash
  839  * chain. If it's there, return a pointer to it, unless it's marked invalid.
  840  */
  841 struct buf *
incore(struct vnode *vp, daddr64_t blkno)
  843 {
  844         struct buf *bp;
  846         /* Search hash chain */
LIST_FOREACH(bp, BUFHASH(vp, blkno), b_hash) {
  848                 if (bp->b_lblkno == blkno && bp->b_vp == vp &&
  849                     !ISSET(bp->b_flags, B_INVAL))
  850                         return (bp);
  851         }
  853         return (NULL);
  854 }
  856 /*
  857  * Get a block of requested size that is associated with
  858  * a given vnode and block offset. If it is found in the
  859  * block cache, mark it as having been found, make it busy
  860  * and return it. Otherwise, return an empty block of the
  861  * correct size. It is up to the caller to ensure that the
  862  * cached blocks be of the correct size.
  863  */
  864 struct buf *
getblk(struct vnode *vp, daddr64_t blkno, int size, int slpflag, int slptimeo)
  866 {
  867         struct bufhashhdr *bh;
  868         struct buf *bp, *nb = NULL;
  869         int s, error;
  871         /*
  872          * XXX
  873          * The following is an inlined version of 'incore()', but with
  874          * the 'invalid' test moved to after the 'busy' test.  It's
  875          * necessary because there are some cases in which the NFS
  876          * code sets B_INVAL prior to writing data to the server, but
  877          * in which the buffers actually contain valid data.  In this
  878          * case, we can't allow the system to allocate a new buffer for
  879          * the block until the write is finished.
  880          */
bh = BUFHASH(vp, blkno);
start:
LIST_FOREACH(bp, BUFHASH(vp, blkno), b_hash) {
  884                 if (bp->b_lblkno != blkno || bp->b_vp != vp)
  885                         continue;
s = splbio();
  888                 if (ISSET(bp->b_flags, B_BUSY)) {
  889                         if (nb != NULL) {
SET(nb->b_flags, B_INVAL);
binshash(nb, &invalhash);
brelse(nb);
nb = NULL;
  894                         }
SET(bp->b_flags, B_WANTED);
error = tsleep(bp, slpflag | (PRIBIO + 1), "getblk",
slptimeo);
splx(s);
  899                         if (error)
  900                                 return (NULL);
  901                         goto start;
  902                 }
  904                 if (!ISSET(bp->b_flags, B_INVAL)) {
SET(bp->b_flags, (B_BUSY | B_CACHE));
bremfree(bp);
splx(s);
  908                         break;
  909                 }
splx(s);
  911         }
  912         if (nb && bp) {
SET(nb->b_flags, B_INVAL);
binshash(nb, &invalhash);
brelse(nb);
nb = NULL;
  917         }
  918         if (bp == NULL && nb == NULL) {
nb = getnewbuf(size, slpflag, slptimeo, &error);
  920                 if (nb == NULL) {
  921                         if (error == ERESTART || error == EINTR)
  922                                 return (NULL);
  923                 }
  924                 goto start;
  925         }
  926         if (nb) {
bp = nb;
binshash(bp, bh);
bp->b_blkno = bp->b_lblkno = blkno;
s = splbio();
bgetvp(vp, bp);
splx(s);
  933         }
  934         return (bp);
  935 }
  937 /*
  938  * Get an empty, disassociated buffer of given size.
  939  */
  940 struct buf *
geteblk(int size)
  942 {
  943         struct buf *bp;
  945         while ((bp = getnewbuf(size, 0, 0, NULL)) == NULL)
  946                 ;
SET(bp->b_flags, B_INVAL);
binshash(bp, &invalhash);
  950         return (bp);
  951 }
  953 /*
  954  * Find a buffer which is available for use.
  955  */
  956 struct buf *
getnewbuf(size_t size, int slpflag, int slptimeo, int *ep)
  958 {
  959         struct buf *bp;
  960         int s, error, queue, qs;
  962 #if 0           /* we would really like this but sblock update kills it */
KASSERT(curproc != syncerproc && curproc != cleanerproc);
  964 #endif
s = splbio();
  967         /*
  968          * Wake up cleaner if we're getting low on pages.
  969          */
  970         if (numdirtypages >= hidirtypages || numcleanpages <= locleanpages)
wakeup(&bd_req);
  973         /* we just ask. it can say no.. */
getsome:
qs = size;
queue = size2cqueue(&qs);
bp = buf_get(qs); /* XXX use qs instead and no need in buf_get? */
  978         if (bp == NULL) {
  979                 /*
  980                  * No free ones, try to reuse a clean one of the same or
  981                  * larger size.
  982                  */
  983                 do {
bp = TAILQ_FIRST(&bufqueues[queue]);
queue++;
  986                 } while (bp == NULL && queue < BQUEUES);
  987         }
  988         if (bp == NULL) {
  989                 /* we couldn't reuse a free one, nothing of the right size */
  990                 /* XXX free 20 buffers per q - ugly hack  should really
  991                  * reuse big ones without truncating. fix later 
  992                  */
  993                 int q, gotsome = 0;
  994                 int freemax = 20; 
  995                 for (q = 1; q < BQUEUES; q++) {
  996                         int i = freemax;
  997                         while (bqpages[q] > bqpagelow
  998                             && (bp = TAILQ_FIRST(&bufqueues[q]))
  999                             && i--) {
gotsome++;
bremfree(bp);
 1002                                 if (LIST_FIRST(&bp->b_dep) != NULL)
buf_deallocate(bp);
 1005                                 if (ISSET(bp->b_flags, B_DELWRI)) {
CLR(bp->b_flags, B_DELWRI);
 1007                                 }
 1009                                 if (bp->b_vp)
brelvp(bp);
buf_put(bp);
 1013                         }
 1014                 }
 1015                 if (gotsome)
 1016                         goto getsome;
 1017         }
 1018         if (bp == NULL) {
 1019                 /* wait for a free buffer of any kind */
needbuffer++;
error = tsleep(&needbuffer, slpflag | (PRIBIO + 1),
 1022                     "getnewbuf", slptimeo);
 1023                 if (ep != NULL) {
 1024                         *ep = error;
 1025                         if (error) {
splx(s);
 1027                                 return (NULL);
 1028                         }
 1029                 }
 1030                 goto getsome;
 1031         }
bremfree(bp);
 1034         /* Buffer is no longer on free lists. */
SET(bp->b_flags, B_BUSY);
 1037 #ifdef DIAGNOSTIC
 1038         if (ISSET(bp->b_flags, B_DELWRI))
panic("Dirty buffer on BQ_CLEAN");
 1040 #endif
 1042         /* disassociate us from our vnode, if we had one... */
 1043         if (bp->b_vp)
brelvp(bp);
splx(s);
 1048 #ifdef DIAGNOSTIC
 1049         /* CLEAN buffers must have no dependencies */ 
 1050         if (LIST_FIRST(&bp->b_dep) != NULL)
panic("BQ_CLEAN has buffer with dependencies");
 1052 #endif
 1054         /* clear out various other fields */
bp->b_flags = B_BUSY;
bp->b_dev = NODEV;
bp->b_blkno = bp->b_lblkno = 0;
bp->b_iodone = NULL;
bp->b_error = 0;
bp->b_resid = 0;
bp->b_bcount = size;
bp->b_dirtyoff = bp->b_dirtyend = 0;
bp->b_validoff = bp->b_validend = 0;
bremhash(bp);
 1066         return (bp);
 1067 }
 1069 /*
 1070  * Buffer cleaning daemon.
 1071  */
 1072 void
buf_daemon(struct proc *p)
 1074 {
 1075         struct timeval starttime, timediff;
 1076         struct buf *bp;
 1077         int s;
cleanerproc = curproc;
s = splbio();
 1082         for (;;) {
 1083                 if (!numdirtypages ||
 1084                     (numdirtypages < hidirtypages && !needbuffer))
tsleep(&bd_req, PRIBIO - 7, "cleaner", 0);
getmicrouptime(&starttime);
 1089                 while ((bp = TAILQ_FIRST(&bufqueues[BQ_DIRTY]))) {
 1090                         struct timeval tv;
 1092                         if (numdirtypages < lodirtypages && !needbuffer)
 1093                                 break;
bremfree(bp);
SET(bp->b_flags, B_BUSY);
splx(s);
 1099                         if (ISSET(bp->b_flags, B_INVAL)) {
brelse(bp);
s = splbio();
 1102                                 continue;
 1103                         }
 1104 #ifdef DIAGNOSTIC
 1105                         if (!ISSET(bp->b_flags, B_DELWRI))
panic("Clean buffer on BQ_DIRTY");
 1107 #endif
 1108                         if (LIST_FIRST(&bp->b_dep) != NULL &&
 1109                             !ISSET(bp->b_flags, B_DEFERRED) &&
buf_countdeps(bp, 0, 0)) {
SET(bp->b_flags, B_DEFERRED);
s = splbio();
numfreepages += btoc(bp->b_bufsize);
numdirtypages += btoc(bp->b_bufsize);
binstailfree(bp, &bufqueues[BQ_DIRTY]);
CLR(bp->b_flags, B_BUSY);
 1117                                 continue;
 1118                         }
bawrite(bp);
 1122                         /* Never allow processing to run for more than 1 sec */
getmicrouptime(&tv);
timersub(&tv, &starttime, &timediff);
 1125                         if (timediff.tv_sec)
 1126                                 break;
s = splbio();
 1129                 }
 1130         }
 1131 }
 1133 /*
 1134  * Wait for operations on the buffer to complete.
 1135  * When they do, extract and return the I/O's error value.
 1136  */
 1137 int
biowait(struct buf *bp)
 1139 {
 1140         int s;
s = splbio();
 1143         while (!ISSET(bp->b_flags, B_DONE))
tsleep(bp, PRIBIO + 1, "biowait", 0);
splx(s);
 1147         /* check for interruption of I/O (e.g. via NFS), then errors. */
 1148         if (ISSET(bp->b_flags, B_EINTR)) {
CLR(bp->b_flags, B_EINTR);
 1150                 return (EINTR);
 1151         }
 1153         if (ISSET(bp->b_flags, B_ERROR))
 1154                 return (bp->b_error ? bp->b_error : EIO);
 1155         else
 1156                 return (0);
 1157 }
 1159 /*
 1160  * Mark I/O complete on a buffer.
 1161  *
 1162  * If a callback has been requested, e.g. the pageout
 1163  * daemon, do so. Otherwise, awaken waiting processes.
 1164  *
 1165  * [ Leffler, et al., says on p.247:
 1166  *      "This routine wakes up the blocked process, frees the buffer
 1167  *      for an asynchronous write, or, for a request by the pagedaemon
 1168  *      process, invokes a procedure specified in the buffer structure" ]
 1169  *
 1170  * In real life, the pagedaemon (or other system processes) wants
 1171  * to do async stuff to, and doesn't want the buffer brelse()'d.
 1172  * (for swap pager, that puts swap buffers on the free lists (!!!),
 1173  * for the vn device, that puts malloc'd buffers on the free lists!)
 1174  *
 1175  * Must be called at splbio().
 1176  */
 1177 void
biodone(struct buf *bp)
 1179 {
splassert(IPL_BIO);
 1182         if (ISSET(bp->b_flags, B_DONE))
panic("biodone already");
SET(bp->b_flags, B_DONE);               /* note that it's done */
 1186         if (LIST_FIRST(&bp->b_dep) != NULL)
buf_complete(bp);
 1189         if (!ISSET(bp->b_flags, B_READ)) {
CLR(bp->b_flags, B_WRITEINPROG);
vwakeup(bp->b_vp);
 1192         }
 1194         if (ISSET(bp->b_flags, B_CALL)) {       /* if necessary, call out */
CLR(bp->b_flags, B_CALL);       /* but note callout done */
 1196                 (*bp->b_iodone)(bp);
 1197         } else {
 1198                 if (ISSET(bp->b_flags, B_ASYNC)) {/* if async, release it */
brelse(bp);
 1200                 } else {                        /* or just wakeup the buffer */
CLR(bp->b_flags, B_WANTED);
wakeup(bp);
 1203                 }
 1204         }
 1205 }
 1207 #if 1
 1208 void
vfs_bufstats(void) {
 1210         return;
 1211 }
 1212 /* #ifdef DDB */
 1213 #else
 1214 /*
 1215  * Print out statistics on the current allocation of the buffer pool.
 1216  * Can be enabled to print out on every ``sync'' by setting "syncprt"
 1217  * in vfs_syscalls.c using sysctl.
 1218  */
 1219 void
vfs_bufstats(void)
 1221 {
 1222         int s, i, j, count;
 1223         struct buf *bp;
 1224         struct bqueues *dp;
 1225         int counts[MAXBSIZE/PAGE_SIZE+1];
 1226         int totals[BQUEUES];
 1227         long ptotals[BQUEUES];
 1228         long pages;
 1229         static char *bname[BQUEUES] = { "CLEAN", "DIRTY", "EMPTY" };
s = splbio();
 1232         for (dp = bufqueues, i = 0; dp < &bufqueues[BQUEUES]; dp++, i++) {
count = 0;
pages = 0;
 1235                 for (j = 0; j <= MAXBSIZE/PAGE_SIZE; j++)
counts[j] = 0;
TAILQ_FOREACH(bp, dp, b_freelist) {
counts[bp->b_bufsize/PAGE_SIZE]++;
count++;
pages += btoc(bp->b_bufsize);
 1241                 }
totals[i] = count;
ptotals[i] = pages;
printf("%s: total-%d(%d pages)", bname[i], count, pages);
 1245                 for (j = 0; j <= MAXBSIZE/PAGE_SIZE; j++)
 1246                         if (counts[j] != 0)
printf(", %d-%d", j * PAGE_SIZE, counts[j]);
printf("\n");
 1249         }
 1250         if ((ptotals[BQ_CLEAN] + ptotals[BQ_DIRTY]) != numfreepages)
printf("numfreepages counter wrong: %ld != %ld\n",
numfreepages, ptotals[BQ_CLEAN] + ptotals[BQ_DIRTY]);
 1253         if (ptotals[BQ_CLEAN] != numcleanpages)
printf("numcleanpages counter wrong: %ld != %ld\n",
numcleanpages, ptotals[<BQ_CLEAN]);
 1256         else
printf("numcleanpages: %ld\n", numcleanpages);
 1258         if (numdirtypages != ptotals[BQ_DIRTY])
printf("numdirtypages counter wrong: %ld != %ld\n",
numdirtypages, ptotals[BQ_DIRTY]);
 1261         else
printf("numdirtypages: %ld\n", numdirtypages);
printf("syncer eating up to %ld pages from %ld reserved\n",
maxcleanpages - hicleanpages, locleanpages);
splx(s);
 1267 }
 1268 #endif /* DEBUG */