-/* vfs_bio.c 4.31 82/05/31 */
-
-#include "../h/param.h"
-#include "../h/systm.h"
-#include "../h/dir.h"
-#include "../h/user.h"
-#include "../h/buf.h"
-#include "../h/conf.h"
-#include "../h/proc.h"
-#include "../h/seg.h"
-#include "../h/pte.h"
-#include "../h/vm.h"
-#include "../h/trace.h"
+/*-
+ * Copyright (c) 1986, 1989, 1993
+ * The Regents of the University of California. All rights reserved.
+ * (c) UNIX System Laboratories, Inc.
+ * All or some portions of this file are derived from material licensed
+ * to the University of California by American Telephone and Telegraph
+ * Co. or Unix System Laboratories, Inc. and are reproduced herein with
+ * the permission of UNIX System Laboratories, Inc.
+ *
+ * This code is derived from software contributed to Berkeley by
+ * Berkeley Software Design Inc.
+ *
+ * %sccs.include.redist.c%
+ *
+ * @(#)vfs_bio.c 8.7 (Berkeley) %G%
+ */
+
+#include <sys/param.h>
+#include <sys/systm.h>
+#include <sys/proc.h>
+#include <sys/buf.h>
+#include <sys/vnode.h>
+#include <sys/mount.h>
+#include <sys/trace.h>
+#include <sys/malloc.h>
+#include <sys/resourcevar.h>
+#include <ufs/ufs/quota.h>
+#include <ufs/ufs/inode.h>
/*
- * Read in (if necessary) the block and return a buffer pointer.
+ * Definitions for the buffer hash lists.
*/
-struct buf *
-bread(dev, blkno, size)
- dev_t dev;
+#define BUFHASH(dvp, lbn) \
+ (&bufhashtbl[((int)(dvp) / sizeof(*(dvp)) + (int)(lbn)) & bufhash])
+LIST_HEAD(bufhashhdr, buf) *bufhashtbl, invalhash;
+u_long bufhash;
+
+/*
+ * Insq/Remq for the buffer hash lists.
+ */
+#define binshash(bp, dp) LIST_INSERT_HEAD(dp, bp, b_hash)
+#define bremhash(bp) LIST_REMOVE(bp, b_hash)
+
+/*
+ * Definitions for the buffer free lists.
+ */
+#define BQUEUES 4 /* number of free buffer queues */
+
+#define BQ_LOCKED 0 /* super-blocks &c */
+#define BQ_LRU 1 /* lru, useful buffers */
+#define BQ_AGE 2 /* rubbish */
+#define BQ_EMPTY 3 /* buffer headers with no memory */
+
+TAILQ_HEAD(bqueues, buf) bufqueues[BQUEUES];
+int needbuffer;
+
+/*
+ * Insq/Remq for the buffer free lists.
+ */
+#define binsheadfree(bp, dp) TAILQ_INSERT_HEAD(dp, bp, b_freelist)
+#define binstailfree(bp, dp) TAILQ_INSERT_TAIL(dp, bp, b_freelist)
+
+void
+bremfree(bp)
+ struct buf *bp;
+{
+ struct bqueues *dp = NULL;
+
+ /*
+ * We only calculate the head of the freelist when removing
+ * the last element of the list as that is the only time that
+ * it is needed (e.g. to reset the tail pointer).
+ *
+ * NB: This makes an assumption about how tailq's are implemented.
+ */
+ if (bp->b_freelist.tqe_next == NULL) {
+ for (dp = bufqueues; dp < &bufqueues[BQUEUES]; dp++)
+ if (dp->tqh_last == &bp->b_freelist.tqe_next)
+ break;
+ if (dp == &bufqueues[BQUEUES])
+ panic("bremfree: lost tail");
+ }
+ TAILQ_REMOVE(dp, bp, b_freelist);
+}
+
+/*
+ * Initialize buffers and hash links for buffers.
+ */
+void
+bufinit()
+{
+ register struct buf *bp;
+ struct bqueues *dp;
+ register int i;
+ int base, residual;
+
+ for (dp = bufqueues; dp < &bufqueues[BQUEUES]; dp++)
+ TAILQ_INIT(dp);
+ bufhashtbl = hashinit(nbuf, M_CACHE, &bufhash);
+ base = bufpages / nbuf;
+ residual = bufpages % nbuf;
+ for (i = 0; i < nbuf; i++) {
+ bp = &buf[i];
+ bzero((char *)bp, sizeof *bp);
+ bp->b_dev = NODEV;
+ bp->b_rcred = NOCRED;
+ bp->b_wcred = NOCRED;
+ bp->b_vnbufs.le_next = NOLIST;
+ bp->b_data = buffers + i * MAXBSIZE;
+ if (i < residual)
+ bp->b_bufsize = (base + 1) * CLBYTES;
+ else
+ bp->b_bufsize = base * CLBYTES;
+ bp->b_flags = B_INVAL;
+ dp = bp->b_bufsize ? &bufqueues[BQ_AGE] : &bufqueues[BQ_EMPTY];
+ binsheadfree(bp, dp);
+ binshash(bp, &invalhash);
+ }
+}
+
+/*
+ * Find the block in the buffer pool.
+ * If the buffer is not present, allocate a new buffer and load
+ * its contents according to the filesystem fill routine.
+ */
+bread(vp, blkno, size, cred, bpp)
+ struct vnode *vp;
daddr_t blkno;
int size;
+ struct ucred *cred;
+ struct buf **bpp;
+#ifdef SECSIZE
+ long secsize;
+#endif SECSIZE
{
+ struct proc *p = curproc; /* XXX */
register struct buf *bp;
- bp = getblk(dev, blkno, size);
- if (bp->b_flags&B_DONE) {
- trace(TR_BREADHIT, dev, blkno);
- return(bp);
+ if (size == 0)
+ panic("bread: size 0");
+#ifdef SECSIZE
+ bp = getblk(dev, blkno, size, secsize);
+#else SECSIZE
+ *bpp = bp = getblk(vp, blkno, size, 0, 0);
+#endif SECSIZE
+ if (bp->b_flags & (B_DONE | B_DELWRI)) {
+ trace(TR_BREADHIT, pack(vp, size), blkno);
+ return (0);
}
bp->b_flags |= B_READ;
- (*bdevsw[major(dev)].d_strategy)(bp);
- trace(TR_BREADMISS, dev, blkno);
- u.u_vm.vm_inblk++; /* pay for read */
- biowait(bp);
- return(bp);
+ if (bp->b_bcount > bp->b_bufsize)
+ panic("bread");
+ if (bp->b_rcred == NOCRED && cred != NOCRED) {
+ crhold(cred);
+ bp->b_rcred = cred;
+ }
+ VOP_STRATEGY(bp);
+ trace(TR_BREADMISS, pack(vp, size), blkno);
+ p->p_stats->p_ru.ru_inblock++; /* pay for read */
+ return (biowait(bp));
}
/*
- * Read in the block, like bread, but also start I/O on the
- * read-ahead block (which is not allocated to the caller)
+ * Operates like bread, but also starts I/O on the N specified
+ * read-ahead blocks.
*/
-struct buf *
-breada(dev, blkno, rablkno, size)
- dev_t dev;
- daddr_t blkno, rablkno;
- int size;
+breadn(vp, blkno, size, rablkno, rabsize, num, cred, bpp)
+ struct vnode *vp;
+ daddr_t blkno; int size;
+#ifdef SECSIZE
+ long secsize;
+#endif SECSIZE
+ daddr_t rablkno[]; int rabsize[];
+ int num;
+ struct ucred *cred;
+ struct buf **bpp;
{
+ struct proc *p = curproc; /* XXX */
register struct buf *bp, *rabp;
+ register int i;
bp = NULL;
/*
- * If the block isn't in core, then allocate
- * a buffer and initiate i/o (getblk checks
- * for a cache hit).
+ * If the block is not memory resident,
+ * allocate a buffer and start I/O.
*/
- if (!incore(dev, blkno)) {
- bp = getblk(dev, blkno, size);
- if ((bp->b_flags&B_DONE) == 0) {
+ if (!incore(vp, blkno)) {
+ *bpp = bp = getblk(vp, blkno, size, 0, 0);
+#endif SECSIZE
+ if ((bp->b_flags & (B_DONE | B_DELWRI)) == 0) {
bp->b_flags |= B_READ;
- (*bdevsw[major(dev)].d_strategy)(bp);
- trace(TR_BREADMISS, dev, blkno);
- u.u_vm.vm_inblk++; /* pay for read */
- } else
- trace(TR_BREADHIT, dev, blkno);
+ if (bp->b_bcount > bp->b_bufsize)
+ panic("breadn");
+ if (bp->b_rcred == NOCRED && cred != NOCRED) {
+ crhold(cred);
+ bp->b_rcred = cred;
+ }
+ VOP_STRATEGY(bp);
+ trace(TR_BREADMISS, pack(vp, size), blkno);
+ p->p_stats->p_ru.ru_inblock++; /* pay for read */
+ } else {
+ trace(TR_BREADHIT, pack(vp, size), blkno);
+ }
}
/*
- * If there's a read-ahead block, start i/o
- * on it also (as above).
+ * If there's read-ahead block(s), start I/O
+ * on them also (as above).
*/
- if (rablkno && !incore(dev, rablkno)) {
- rabp = getblk(dev, rablkno, size);
- if (rabp->b_flags & B_DONE) {
+ for (i = 0; i < num; i++) {
+ if (incore(vp, rablkno[i]))
+ continue;
+ rabp = getblk(vp, rablkno[i], rabsize[i], 0, 0);
+#endif SECSIZE
+ if (rabp->b_flags & (B_DONE | B_DELWRI)) {
brelse(rabp);
- trace(TR_BREADHITRA, dev, blkno);
+ trace(TR_BREADHITRA, pack(vp, rabsize[i]), rablkno[i]);
} else {
- rabp->b_flags |= B_READ|B_ASYNC;
- (*bdevsw[major(dev)].d_strategy)(rabp);
- trace(TR_BREADMISSRA, dev, rablock);
- u.u_vm.vm_inblk++; /* pay in advance */
+ rabp->b_flags |= B_ASYNC | B_READ;
+ if (rabp->b_bcount > rabp->b_bufsize)
+ panic("breadrabp");
+ if (rabp->b_rcred == NOCRED && cred != NOCRED) {
+ crhold(cred);
+ rabp->b_rcred = cred;
+ }
+ VOP_STRATEGY(rabp);
+ trace(TR_BREADMISSRA, pack(vp, rabsize[i]), rablkno[i]);
+ p->p_stats->p_ru.ru_inblock++; /* pay in advance */
}
}
/*
- * If we get here with bp NULL, then the block
- * must've been in core and bread will find it for us.
+ * If block was memory resident, let bread get it.
+ * If block was not memory resident, the read was
+ * started above, so just wait for the read to complete.
*/
- if(bp == NULL)
- return(bread(dev, blkno, size));
- biowait(bp);
- return(bp);
+ if (bp == NULL)
+#ifdef SECSIZE
+ return (bread(dev, blkno, size, secsize));
+#else SECSIZE
+ return (bread(vp, blkno, size, cred, bpp));
+ return (biowait(bp));
}
/*
- * Write the buffer, waiting for completion.
- * Then release the buffer.
+ * Synchronous write.
+ * Release buffer on completion.
*/
bwrite(bp)
register struct buf *bp;
{
- register flag;
+ struct proc *p = curproc; /* XXX */
+ register int flag;
+ int s, error = 0;
+ if (bp->b_vp && (bp->b_vp->v_mount->mnt_flag & MNT_ASYNC))
+ bp->b_flags |= B_ASYNC;
flag = bp->b_flags;
- bp->b_flags &= ~(B_READ | B_DONE | B_ERROR | B_DELWRI | B_AGE);
- if ((flag&B_DELWRI) == 0)
- u.u_vm.vm_oublk++; /* noone paid yet */
- trace(TR_BWRITE, bp->b_dev, bp->b_blkno);
- (*bdevsw[major(bp->b_dev)].d_strategy)(bp);
+ bp->b_flags &= ~(B_READ | B_DONE | B_ERROR | B_DELWRI);
+ if (flag & B_ASYNC) {
+ if ((flag & B_DELWRI) == 0)
+ p->p_stats->p_ru.ru_oublock++; /* no one paid yet */
+ else
+ reassignbuf(bp, bp->b_vp);
+ }
+ trace(TR_BWRITE, pack(bp->b_vp, bp->b_bcount), bp->b_lblkno);
+ if (bp->b_bcount > bp->b_bufsize)
+ panic("bwrite");
+ s = splbio();
+ bp->b_vp->v_numoutput++;
+ bp->b_flags |= B_WRITEINPROG;
+ splx(s);
+ VOP_STRATEGY(bp);
/*
- * If the write was synchronous, then await i/o completion.
+ * If the write was synchronous, then await I/O completion.
* If the write was "delayed", then we put the buffer on
- * the q of blocks awaiting i/o completion status.
- * Otherwise, the i/o must be finished and we check for
- * an error.
+ * the queue of blocks awaiting I/O completion status.
*/
- if ((flag&B_ASYNC) == 0) {
- biowait(bp);
+ if ((flag & B_ASYNC) == 0) {
+ error = biowait(bp);
+ if ((flag&B_DELWRI) == 0)
+ p->p_stats->p_ru.ru_oublock++; /* no one paid yet */
+ else
+ reassignbuf(bp, bp->b_vp);
+ if (bp->b_flags & B_EINTR) {
+ bp->b_flags &= ~B_EINTR;
+ error = EINTR;
+ }
brelse(bp);
- } else if (flag & B_DELWRI)
+ } else if (flag & B_DELWRI) {
+ s = splbio();
bp->b_flags |= B_AGE;
- else
- geterror(bp);
+ splx(s);
+ }
+ return (error);
+}
+
+int
+vn_bwrite(ap)
+ struct vop_bwrite_args *ap;
+{
+
+ return (bwrite(ap->a_bp));
}
+
/*
- * Release the buffer, marking it so that if it is grabbed
- * for another purpose it will be written out before being
- * given up (e.g. when writing a partial block where it is
- * assumed that another write for the same block will soon follow).
- * This can't be done for magtape, since writes must be done
- * in the same order as requested.
+ * Delayed write.
+ *
+ * The buffer is marked dirty, but is not queued for I/O.
+ * This routine should be used when the buffer is expected
+ * to be modified again soon, typically a small write that
+ * partially fills a buffer.
+ *
+ * NB: magnetic tapes cannot be delayed; they must be
+ * written in the order that the writes are requested.
*/
bdwrite(bp)
register struct buf *bp;
{
- register int flags;
+ struct proc *p = curproc; /* XXX */
- if ((bp->b_flags&B_DELWRI) == 0)
- u.u_vm.vm_oublk++; /* noone paid yet */
- flags = bdevsw[major(bp->b_dev)].d_flags;
- if(flags & B_TAPE)
+ if ((bp->b_flags & B_DELWRI) == 0) {
+ bp->b_flags |= B_DELWRI;
+ reassignbuf(bp, bp->b_vp);
+ p->p_stats->p_ru.ru_oublock++; /* no one paid yet */
+ }
+ /*
+ * If this is a tape drive, the write must be initiated.
+ */
+ if (bdevsw[major(bp->b_dev)].d_flags & B_TAPE)
bawrite(bp);
- else {
- bp->b_flags |= B_DELWRI | B_DONE;
+ } else {
+ bp->b_flags |= (B_DONE | B_DELWRI);
brelse(bp);
}
}
/*
- * Release the buffer, start I/O on it, but don't wait for completion.
+ * Asynchronous write.
+ * Start I/O on a buffer, but do not wait for it to complete.
+ * The buffer is released when the I/O completes.
*/
bawrite(bp)
register struct buf *bp;
{
+ /*
+ * Setting the ASYNC flag causes bwrite to return
+ * after starting the I/O.
+ */
bp->b_flags |= B_ASYNC;
- bwrite(bp);
+ (void) VOP_BWRITE(bp);
}
/*
- * Release the buffer, with no I/O implied.
+ * Release a buffer.
+ * Even if the buffer is dirty, no I/O is started.
*/
brelse(bp)
register struct buf *bp;
{
- register struct buf *flist;
- register s;
+ register struct bqueues *flist;
+ int s;
+ trace(TR_BRELSE, pack(bp->b_vp, bp->b_bufsize), bp->b_lblkno);
/*
- * If someone's waiting for the buffer, or
- * is waiting for a buffer wake 'em up.
+ * If a process is waiting for the buffer, or
+ * is waiting for a free buffer, awaken it.
*/
- if (bp->b_flags&B_WANTED)
+ if (bp->b_flags & B_WANTED)
wakeup((caddr_t)bp);
- if (bfreelist[0].b_flags&B_WANTED) {
- bfreelist[0].b_flags &= ~B_WANTED;
- wakeup((caddr_t)bfreelist);
+ if (needbuffer) {
+ needbuffer = 0;
+ wakeup((caddr_t)&needbuffer);
+ }
+ /*
+ * Retry I/O for locked buffers rather than invalidating them.
+ */
+ s = splbio();
+ if ((bp->b_flags & B_ERROR) && (bp->b_flags & B_LOCKED))
+ bp->b_flags &= ~B_ERROR;
+ /*
+ * Disassociate buffers that are no longer valid.
+ */
+ if (bp->b_flags & (B_NOCACHE | B_ERROR))
+ bp->b_flags |= B_INVAL;
+ if ((bp->b_bufsize <= 0) || (bp->b_flags & (B_ERROR | B_INVAL))) {
+ if (bp->b_vp)
+ brelvp(bp);
+ bp->b_flags &= ~B_DELWRI;
}
- if (bp->b_flags&B_ERROR)
- if (bp->b_flags & B_LOCKED)
- bp->b_flags &= ~B_ERROR; /* try again later */
- else
- bp->b_dev = NODEV; /* no assoc */
-
/*
* Stick the buffer back on a free list.
*/
- s = spl6();
- if (bp->b_flags & (B_ERROR|B_INVAL)) {
+ if (bp->b_bufsize <= 0) {
+ /* block has no buffer ... put at front of unused buffer list */
+ flist = &bufqueues[BQ_EMPTY];
+ binsheadfree(bp, flist);
+ } else if (bp->b_flags & (B_ERROR | B_INVAL)) {
/* block has no info ... put at front of most free list */
- flist = &bfreelist[BQUEUES-1];
+ flist = &bufqueues[BQ_AGE];
binsheadfree(bp, flist);
} else {
if (bp->b_flags & B_LOCKED)
- flist = &bfreelist[BQ_LOCKED];
+ flist = &bufqueues[BQ_LOCKED];
else if (bp->b_flags & B_AGE)
- flist = &bfreelist[BQ_AGE];
+ flist = &bufqueues[BQ_AGE];
else
- flist = &bfreelist[BQ_LRU];
+ flist = &bufqueues[BQ_LRU];
binstailfree(bp, flist);
}
- bp->b_flags &= ~(B_WANTED|B_BUSY|B_ASYNC|B_AGE);
+ bp->b_flags &= ~(B_WANTED | B_BUSY | B_ASYNC | B_AGE | B_NOCACHE);
splx(s);
}
/*
- * See if the block is associated with some buffer
- * (mainly to avoid getting hung up on a wait in breada)
+ * Check to see if a block is currently memory resident.
*/
-incore(dev, blkno)
- dev_t dev;
+struct buf *
+incore(vp, blkno)
+ struct vnode *vp;
daddr_t blkno;
{
register struct buf *bp;
- register struct buf *dp;
- dp = BUFHASH(dev, blkno);
- for (bp = dp->b_forw; bp != dp; bp = bp->b_forw)
- if (bp->b_blkno == blkno && bp->b_dev == dev &&
+ for (bp = BUFHASH(vp, blkno)->lh_first; bp; bp = bp->b_hash.le_next)
+ if (bp->b_lblkno == blkno && bp->b_vp == vp &&
(bp->b_flags & B_INVAL) == 0)
- return (1);
- return (0);
-}
-
-struct buf *
-baddr(dev, blkno, size)
- dev_t dev;
- daddr_t blkno;
- int size;
-{
-
- if (incore(dev, blkno))
- return (bread(dev, blkno, size));
- return (0);
+ return (bp);
+ return (NULL);
}
/*
- * Assign a buffer for the given block. If the appropriate
- * block is already associated, return it; otherwise search
- * for the oldest non-busy buffer and reassign it.
- *
- * We use splx here because this routine may be called
- * on the interrupt stack during a dump, and we don't
- * want to lower the ipl back to 0.
+ * Check to see if a block is currently memory resident.
+ * If it is resident, return it. If it is not resident,
+ * allocate a new buffer and assign it to the block.
*/
struct buf *
-getblk(dev, blkno, size)
- dev_t dev;
+#ifdef SECSIZE
+getblk(dev, blkno, size, secsize)
+#else SECSIZE
+getblk(vp, blkno, size, slpflag, slptimeo)
+ register struct vnode *vp;
daddr_t blkno;
- int size;
+ int size, slpflag, slptimeo;
+#ifdef SECSIZE
+ long secsize;
+#endif SECSIZE
{
- register struct buf *bp, *dp, *ep;
- int s;
+ register struct buf *bp;
+ struct bufhashhdr *dp;
+ int s, error;
- if ((unsigned)blkno >= 1 << (sizeof(int)*NBBY-PGSHIFT))
- blkno = 1 << ((sizeof(int)*NBBY-PGSHIFT) + 1);
+ if (size > MAXBSIZE)
+ panic("getblk: size too big");
/*
- * Search the cache for the block. If we hit, but
- * the buffer is in use for i/o, then we wait until
- * the i/o has completed.
+ * Search the cache for the block. If the buffer is found,
+ * but it is currently locked, the we must wait for it to
+ * become available.
*/
- dp = BUFHASH(dev, blkno);
+ dp = BUFHASH(vp, blkno);
loop:
- for (bp = dp->b_forw; bp != dp; bp = bp->b_forw) {
- if (bp->b_blkno != blkno || bp->b_dev != dev ||
- bp->b_flags&B_INVAL)
+ for (bp = dp->lh_first; bp; bp = bp->b_hash.le_next) {
+ if (bp->b_lblkno != blkno || bp->b_vp != vp)
continue;
- s = spl6();
- if (bp->b_flags&B_BUSY) {
+ s = splbio();
+ if (bp->b_flags & B_BUSY) {
bp->b_flags |= B_WANTED;
- sleep((caddr_t)bp, PRIBIO+1);
+ error = tsleep((caddr_t)bp, slpflag | (PRIBIO + 1),
+ "getblk", slptimeo);
splx(s);
+ if (error)
+ return (NULL);
goto loop;
}
+ /*
+ * The test for B_INVAL is moved down here, since there
+ * are cases where B_INVAL is set before VOP_BWRITE() is
+ * called and for NFS, the process cannot be allowed to
+ * allocate a new buffer for the same block until the write
+ * back to the server has been completed. (ie. B_BUSY clears)
+ */
+ if (bp->b_flags & B_INVAL) {
+ splx(s);
+ continue;
+ }
+ bremfree(bp);
+ bp->b_flags |= B_BUSY;
splx(s);
- notavail(bp);
- brealloc(bp, size);
+ if (bp->b_bcount != size) {
+ printf("getblk: stray size");
+ bp->b_flags |= B_INVAL;
+ VOP_BWRITE(bp);
+ goto loop;
+ }
bp->b_flags |= B_CACHE;
- return(bp);
+ return (bp);
}
- if (major(dev) >= nblkdev)
- panic("blkdev");
/*
- * Not found in the cache, select something from
- * a free list. Preference is to LRU list, then AGE list.
+ * The loop back to the top when getnewbuf() fails is because
+ * stateless filesystems like NFS have no node locks. Thus,
+ * there is a slight chance that more than one process will
+ * try and getnewbuf() for the same block concurrently when
+ * the first sleeps in getnewbuf(). So after a sleep, go back
+ * up to the top to check the hash lists again.
*/
- s = spl6();
- for (ep = &bfreelist[BQUEUES-1]; ep > bfreelist; ep--)
- if (ep->av_forw != ep)
- break;
- if (ep == bfreelist) { /* no free blocks at all */
- ep->b_flags |= B_WANTED;
- sleep((caddr_t)ep, PRIBIO+1);
- splx(s);
- goto loop;
- }
- splx(s);
- bp = ep->av_forw;
- notavail(bp);
- if (bp->b_flags & B_DELWRI) {
- bp->b_flags |= B_ASYNC;
- bwrite(bp);
+ if ((bp = getnewbuf(slpflag, slptimeo)) == 0)
goto loop;
- }
- trace(TR_BRELSE, bp->b_dev, bp->b_blkno);
- bp->b_flags = B_BUSY;
- bfree(bp);
bremhash(bp);
- binshash(bp, dp);
- bp->b_dev = dev;
+ bgetvp(vp, bp);
+ bp->b_bcount = 0;
+ bp->b_lblkno = blkno;
+#ifdef SECSIZE
+ bp->b_blksize = secsize;
+#endif SECSIZE
bp->b_blkno = blkno;
- brealloc(bp, size);
- return(bp);
+ bp->b_error = 0;
+ bp->b_resid = 0;
+ binshash(bp, dp);
+ allocbuf(bp, size);
+ return (bp);
}
/*
- * get an empty block,
- * not assigned to any particular device
+ * Allocate a buffer.
+ * The caller will assign it to a block.
*/
struct buf *
geteblk(size)
int size;
{
- register struct buf *bp, *dp;
- int s;
+ register struct buf *bp;
-loop:
- s = spl6();
- for (dp = &bfreelist[BQUEUES-1]; dp > bfreelist; dp--)
- if (dp->av_forw != dp)
- break;
- if (dp == bfreelist) { /* no free blocks */
- dp->b_flags |= B_WANTED;
- sleep((caddr_t)dp, PRIBIO+1);
- goto loop;
- }
- splx(s);
- bp = dp->av_forw;
- notavail(bp);
- if (bp->b_flags & B_DELWRI) {
- bp->b_flags |= B_ASYNC;
- bwrite(bp);
- goto loop;
- }
- trace(TR_BRELSE, bp->b_dev, bp->b_blkno);
- bp->b_flags = B_BUSY|B_INVAL;
- bfree(bp);
+ if (size > MAXBSIZE)
+ panic("geteblk: size too big");
+ while ((bp = getnewbuf(0, 0)) == NULL)
+ /* void */;
+ bp->b_flags |= B_INVAL;
bremhash(bp);
- binshash(bp, dp);
- bp->b_dev = (dev_t)NODEV;
- bp->b_bcount = size;
- return(bp);
+ binshash(bp, &invalhash);
+ bp->b_bcount = 0;
+#ifdef SECSIZE
+ bp->b_blksize = DEV_BSIZE;
+#endif SECSIZE
+ bp->b_error = 0;
+ bp->b_resid = 0;
+ allocbuf(bp, size);
+ return (bp);
}
/*
- * Allocate space associated with a buffer.
+ * Expand or contract the actual memory allocated to a buffer.
+ * If no memory is available, release buffer and take error exit.
*/
-brealloc(bp, size)
- register struct buf *bp;
+allocbuf(tp, size)
+ register struct buf *tp;
int size;
{
- daddr_t start, last;
- register struct buf *ep;
- struct buf *dp;
- int s;
+ register struct buf *bp, *ep;
+ int sizealloc, take, s;
+ sizealloc = roundup(size, CLBYTES);
/*
- * First need to make sure that all overlaping previous I/O
- * is dispatched with.
+ * Buffer size does not change
*/
- if (size == bp->b_bcount)
- return;
- if (size < bp->b_bcount) {
- bp->b_bcount = size;
- return;
- }
- start = bp->b_blkno + (bp->b_bcount / DEV_BSIZE);
- last = bp->b_blkno + (size / DEV_BSIZE) - 1;
- if (bp->b_bcount == 0) {
- start++;
- if (start == last)
- goto allocit;
- }
- dp = BUFHASH(bp->b_dev, bp->b_blkno);
-loop:
- for (ep = dp->b_forw; ep != dp; ep = ep->b_forw) {
- if (ep->b_blkno < start || ep->b_blkno > last ||
- ep->b_dev != bp->b_dev || ep->b_flags&B_INVAL)
- continue;
- s = spl6();
- if (ep->b_flags&B_BUSY) {
- ep->b_flags |= B_WANTED;
- sleep((caddr_t)ep, PRIBIO+1);
- (void) splx(s);
- goto loop;
- }
- (void) splx(s);
- /*
- * What we would really like to do is kill this
- * I/O since it is now useless. We cannot do that
- * so we force it to complete, so that it cannot
- * over-write our useful data later.
- */
- if (ep->b_flags & B_DELWRI) {
- notavail(ep);
- ep->b_flags |= B_ASYNC;
- bwrite(ep);
- goto loop;
- }
+ if (sizealloc == tp->b_bufsize)
+ goto out;
+ /*
+ * Buffer size is shrinking.
+ * Place excess space in a buffer header taken from the
+ * BQ_EMPTY buffer list and placed on the "most free" list.
+ * If no extra buffer headers are available, leave the
+ * extra space in the present buffer.
+ */
+ if (sizealloc < tp->b_bufsize) {
+ if ((ep = bufqueues[BQ_EMPTY].tqh_first) == NULL)
+ goto out;
+ s = splbio();
+ bremfree(ep);
+ ep->b_flags |= B_BUSY;
+ splx(s);
+ pagemove((char *)tp->b_data + sizealloc, ep->b_data,
+ (int)tp->b_bufsize - sizealloc);
+ ep->b_bufsize = tp->b_bufsize - sizealloc;
+ tp->b_bufsize = sizealloc;
+ ep->b_flags |= B_INVAL;
+ ep->b_bcount = 0;
+ brelse(ep);
+ goto out;
}
-allocit:
/*
- * Here the buffer is already available, so all we
- * need to do is set the size. Someday a better memory
- * management scheme will be implemented.
+ * More buffer space is needed. Get it out of buffers on
+ * the "most free" list, placing the empty headers on the
+ * BQ_EMPTY buffer header list.
*/
- bp->b_bcount = size;
+ while (tp->b_bufsize < sizealloc) {
+ take = sizealloc - tp->b_bufsize;
+ while ((bp = getnewbuf(0, 0)) == NULL)
+ /* void */;
+ if (take >= bp->b_bufsize)
+ take = bp->b_bufsize;
+ pagemove(&((char *)bp->b_data)[bp->b_bufsize - take],
+ &((char *)tp->b_data)[tp->b_bufsize], take);
+ tp->b_bufsize += take;
+ bp->b_bufsize = bp->b_bufsize - take;
+ if (bp->b_bcount > bp->b_bufsize)
+ bp->b_bcount = bp->b_bufsize;
+ if (bp->b_bufsize <= 0) {
+ bremhash(bp);
+ binshash(bp, &invalhash);
+ bp->b_dev = NODEV;
+ bp->b_error = 0;
+ bp->b_flags |= B_INVAL;
+ }
+ brelse(bp);
+ }
+out:
+ tp->b_bcount = size;
+ return (1);
}
/*
- * Release space associated with a buffer.
+ * Find a buffer which is available for use.
+ * Select something from a free list.
+ * Preference is to AGE list, then LRU list.
*/
-bfree(bp)
- struct buf *bp;
+struct buf *
+getnewbuf(slpflag, slptimeo)
+ int slpflag, slptimeo;
{
- /*
- * Here the buffer does not change, so all we
- * need to do is set the size. Someday a better memory
- * management scheme will be implemented.
- */
- bp->b_bcount = 0;
+ register struct buf *bp;
+ register struct bqueues *dp;
+ register struct ucred *cred;
+ int s;
+ struct buf *abp;
+ static int losecnt = 0;
+
+loop:
+ s = splbio();
+ abp = NULL;
+ for (dp = &bufqueues[BQ_AGE]; dp > bufqueues; dp--) {
+ for (bp = dp->qe_next; bp; bp = bp->b_freelist.qe_next) {
+ if (abp == NULL)
+ abp = bp;
+ if ((bp->b_flags & B_DELWRI) &&
+ bp->b_vp && VOP_ISLOCKED(bp->b_vp))
+ continue;
+ goto found;
+ }
+ }
+ if (dp == bufqueues) { /* no free blocks */
+ if (abp) {
+ bp = abp;
+ bp->b_flags |= B_XXX;
+ if (losecnt++ < 20) {
+ vprint("skipping blkno check", bp->b_vp);
+ printf("\tlblkno %d, blkno %d\n",
+ bp->b_lblkno, bp->b_blkno);
+ }
+ goto found;
+ }
+ needbuffer = 1;
+ (void) tsleep((caddr_t)&needbuffer, slpflag | (PRIBIO + 1),
+ "getnewbuf", slptimeo);
+ splx(s);
+ return (NULL);
+ }
+found:
+ bremfree(bp);
+ bp->b_flags |= B_BUSY;
+ splx(s);
+ if (bp->b_flags & B_DELWRI) {
+ (void) bawrite(bp);
+ goto loop;
+ }
+ trace(TR_BRELSE, pack(bp->b_vp, bp->b_bufsize), bp->b_lblkno);
+ if (bp->b_vp)
+ brelvp(bp);
+ if (bp->b_rcred != NOCRED) {
+ cred = bp->b_rcred;
+ bp->b_rcred = NOCRED;
+ crfree(cred);
+ }
+ if (bp->b_wcred != NOCRED) {
+ cred = bp->b_wcred;
+ bp->b_wcred = NOCRED;
+ crfree(cred);
+ }
+ bp->b_flags = B_BUSY;
+ bp->b_dirtyoff = bp->b_dirtyend = 0;
+ bp->b_validoff = bp->b_validend = 0;
+ return (bp);
}
/*
- * Wait for I/O completion on the buffer; return errors
- * to the user.
+ * Wait for I/O to complete.
+ *
+ * Extract and return any errors associated with the I/O.
+ * If the error flag is set, but no specific error is
+ * given, return EIO.
*/
biowait(bp)
register struct buf *bp;
{
int s;
- s = spl6();
- while ((bp->b_flags&B_DONE)==0)
+ s = splbio();
+ while ((bp->b_flags & B_DONE) == 0)
sleep((caddr_t)bp, PRIBIO);
splx(s);
- geterror(bp);
+ if ((bp->b_flags & B_ERROR) == 0)
+ return (0);
+ if (bp->b_error)
+ return (bp->b_error);
+ return (EIO);
}
/*
- * Mark I/O complete on a buffer. If the header
- * indicates a dirty page push completion, the
- * header is inserted into the ``cleaned'' list
- * to be processed by the pageout daemon. Otherwise
- * release it if I/O is asynchronous, and wake
- * up anyone waiting for it.
+ * Mark I/O complete on a buffer.
+ *
+ * If a callback has been requested, e.g. the pageout
+ * daemon, do so. Otherwise, awaken waiting processes.
*/
+void
biodone(bp)
register struct buf *bp;
{
- register int s;
if (bp->b_flags & B_DONE)
panic("dup biodone");
bp->b_flags |= B_DONE;
- if (bp->b_flags & B_DIRTY) {
- if (bp->b_flags & B_ERROR)
- panic("IO err in push");
- s = spl6();
- bp->av_forw = bclnlist;
- bp->b_bcount = swsize[bp - swbuf];
- bp->b_pfcent = swpf[bp - swbuf];
- cnt.v_pgout++;
- cnt.v_pgpgout += bp->b_bcount / NBPG;
- bclnlist = bp;
- if (bswlist.b_flags & B_WANTED)
- wakeup((caddr_t)&proc[2]);
- splx(s);
+ if ((bp->b_flags & B_READ) == 0)
+ vwakeup(bp);
+ if (bp->b_flags & B_CALL) {
+ bp->b_flags &= ~B_CALL;
+ (*bp->b_iodone)(bp);
return;
}
- if (bp->b_flags&B_ASYNC)
+ if (bp->b_flags & B_ASYNC)
brelse(bp);
else {
bp->b_flags &= ~B_WANTED;
}
}
-/*
- * make sure all write-behind blocks
- * on dev (or NODEV for all)
- * are flushed out.
- * (from umount and update)
- * (and temporarily pagein)
- */
-bflush(dev)
- dev_t dev;
+int
+count_lock_queue()
{
register struct buf *bp;
- register struct buf *flist;
- int s;
-
-loop:
- s = spl6();
- for (flist = bfreelist; flist < &bfreelist[BQUEUES]; flist++)
- for (bp = flist->av_forw; bp != flist; bp = bp->av_forw) {
- if ((bp->b_flags & B_DELWRI) == 0)
- continue;
- if (dev == NODEV || dev == bp->b_dev) {
- bp->b_flags |= B_ASYNC;
- notavail(bp);
- bwrite(bp);
- goto loop;
- }
- }
- splx(s);
-}
-
-/*
- * Pick up the device's error number and pass it to the user;
- * if there is an error but the number is 0 set a generalized
- * code. Actually the latter is always true because devices
- * don't yet return specific errors.
- */
-geterror(bp)
- register struct buf *bp;
-{
+ register int ret;
- if (bp->b_flags&B_ERROR)
- if ((u.u_error = bp->b_error)==0)
- u.u_error = EIO;
+ for (ret = 0, bp = (struct buf *)bufqueues[BQ_LOCKED].tqh_first;
+ bp; bp = (struct buf *)bp->b_freelist.tqe_next)
+ ++ret;
+ return(ret);
}
+#ifdef DIAGNOSTIC
/*
- * Invalidate in core blocks belonging to closed or umounted filesystem
- *
- * This is not nicely done at all - the buffer ought to be removed from the
- * hash chains & have its dev/blkno fields clobbered, but unfortunately we
- * can't do that here, as it is quite possible that the block is still
- * being used for i/o. Eventually, all disc drivers should be forced to
- * have a close routine, which ought ensure that the queue is empty, then
- * properly flush the queues. Until that happy day, this suffices for
- * correctness. ... kre
+ * Print out statistics on the current allocation of the buffer pool.
+ * Can be enabled to print out on every ``sync'' by setting "syncprt"
+ * in vfs_syscalls.c using sysctl.
*/
-binval(dev)
- dev_t dev;
+void
+vfs_bufstats()
{
+ int s, i, j, count;
register struct buf *bp;
- register struct bufhd *hp;
-#define dp ((struct buf *)hp)
-
- for (hp = bufhash; hp < &bufhash[BUFHSZ]; hp++)
- for (bp = dp->b_forw; bp != dp; bp = bp->b_forw)
- if (bp->b_dev == dev)
- bp->b_flags |= B_INVAL;
+ register struct bqueues *dp;
+ int counts[MAXBSIZE/CLBYTES+1];
+ static char *bname[BQUEUES] = { "LOCKED", "LRU", "AGE", "EMPTY" };
+
+ for (dp = bufqueues, i = 0; dp < &bufqueues[BQUEUES]; dp++, i++) {
+ count = 0;
+ for (j = 0; j <= MAXBSIZE/CLBYTES; j++)
+ counts[j] = 0;
+ s = splbio();
+ for (bp = dp->tqh_first; bp; bp = bp->b_freelist.tqe_next) {
+ counts[bp->b_bufsize/CLBYTES]++;
+ count++;
+ }
+ splx(s);
+ printf("%s: total-%d", bname[i], count);
+ for (j = 0; j <= MAXBSIZE/CLBYTES; j++)
+ if (counts[j] != 0)
+ printf(", %d-%d", j * CLBYTES, counts[j]);
+ printf("\n");
+ }
}
+#endif /* DIAGNOSTIC */