diff options
author | mckusick <mckusick@FreeBSD.org> | 1999-06-26 02:47:16 +0000 |
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committer | mckusick <mckusick@FreeBSD.org> | 1999-06-26 02:47:16 +0000 |
commit | 5b58f2f951911f1075788268f99efccf1dba60eb (patch) | |
tree | 3f01ed42f71231eaa6a8cfa08b267634f1923fb1 /sys/kern/vfs_bio.c | |
parent | 3213b13650cb2206bbd62b5b1764d148750f63a0 (diff) | |
download | FreeBSD-src-5b58f2f951911f1075788268f99efccf1dba60eb.zip FreeBSD-src-5b58f2f951911f1075788268f99efccf1dba60eb.tar.gz |
Convert buffer locking from using the B_BUSY and B_WANTED flags to using
lockmgr locks. This commit should be functionally equivalent to the old
semantics. That is, all buffer locking is done with LK_EXCLUSIVE
requests. Changes to take advantage of LK_SHARED and LK_RECURSIVE will
be done in future commits.
Diffstat (limited to 'sys/kern/vfs_bio.c')
-rw-r--r-- | sys/kern/vfs_bio.c | 109 |
1 files changed, 59 insertions, 50 deletions
diff --git a/sys/kern/vfs_bio.c b/sys/kern/vfs_bio.c index 4a7c2e4..48f2c38 100644 --- a/sys/kern/vfs_bio.c +++ b/sys/kern/vfs_bio.c @@ -11,7 +11,7 @@ * 2. Absolutely no warranty of function or purpose is made by the author * John S. Dyson. * - * $Id: vfs_bio.c,v 1.214 1999/06/16 23:27:31 mckusick Exp $ + * $Id: vfs_bio.c,v 1.215 1999/06/22 01:39:53 mckusick Exp $ */ /* @@ -139,6 +139,7 @@ SYSCTL_INT(_vfs, OID_AUTO, kvafreespace, CTLFLAG_RD, static LIST_HEAD(bufhashhdr, buf) bufhashtbl[BUFHSZ], invalhash; struct bqueues bufqueues[BUFFER_QUEUES] = { { 0 } }; +char *buf_wmesg = BUF_WMESG; extern int vm_swap_size; @@ -250,6 +251,7 @@ bufinit() TAILQ_INIT(&bswlist); LIST_INIT(&invalhash); + simple_lock_init(&buftimelock); /* first, make a null hash table */ for (i = 0; i < BUFHSZ; i++) @@ -270,6 +272,7 @@ bufinit() bp->b_qindex = QUEUE_EMPTY; bp->b_xflags = 0; LIST_INIT(&bp->b_dep); + BUF_LOCKINIT(bp); TAILQ_INSERT_TAIL(&bufqueues[QUEUE_EMPTY], bp, b_freelist); LIST_INSERT_HEAD(&invalhash, bp, b_hash); } @@ -359,7 +362,14 @@ bremfree(struct buf * bp) if (bp->b_qindex == QUEUE_EMPTY) { kvafreespace -= bp->b_kvasize; } - TAILQ_REMOVE(&bufqueues[bp->b_qindex], bp, b_freelist); + if (BUF_REFCNT(bp) == 1) + TAILQ_REMOVE(&bufqueues[bp->b_qindex], bp, b_freelist); + else if (BUF_REFCNT(bp) == 0) + panic("bremfree: not locked"); + else + /* Temporary panic to verify exclusive locking */ + /* This panic goes away when we allow shared refs */ + panic("bremfree: multiple refs"); bp->b_qindex = QUEUE_NONE; runningbufspace += bp->b_bufsize; } else { @@ -471,6 +481,7 @@ breadn(struct vnode * vp, daddr_t blkno, int size, rabp->b_rcred = cred; } vfs_busy_pages(rabp, 0); + BUF_KERNPROC(bp); VOP_STRATEGY(vp, rabp); } else { brelse(rabp); @@ -509,7 +520,7 @@ bwrite(struct buf * bp) oldflags = bp->b_flags; #if !defined(MAX_PERF) - if ((bp->b_flags & B_BUSY) == 0) + if (BUF_REFCNT(bp) == 0) panic("bwrite: buffer is not busy???"); #endif s = splbio(); @@ -523,6 +534,7 @@ bwrite(struct buf * bp) if (curproc != NULL) curproc->p_stats->p_ru.ru_oublock++; splx(s); + BUF_KERNPROC(bp); VOP_STRATEGY(bp->b_vp, bp); /* @@ -567,9 +579,8 @@ bdwrite(struct buf * bp) struct vnode *vp; #if !defined(MAX_PERF) - if ((bp->b_flags & B_BUSY) == 0) { + if (BUF_REFCNT(bp) == 0) panic("bdwrite: buffer is not busy"); - } #endif if (bp->b_flags & B_INVAL) { @@ -883,6 +894,16 @@ brelse(struct buf * bp) if (bp->b_qindex != QUEUE_NONE) panic("brelse: free buffer onto another queue???"); #endif + if (BUF_REFCNT(bp) > 1) { + /* Temporary panic to verify exclusive locking */ + /* This panic goes away when we allow shared refs */ + panic("brelse: multiple refs"); + /* do not release to free list */ + BUF_UNLOCK(bp); + splx(s); + return; + } + /* enqueue */ /* buffers with no memory */ @@ -948,14 +969,9 @@ brelse(struct buf * bp) if (bp->b_bufsize) bufspacewakeup(); - if (bp->b_flags & B_WANTED) { - bp->b_flags &= ~(B_WANTED | B_AGE); - wakeup(bp); - } - /* unlock */ - bp->b_flags &= ~(B_ORDERED | B_WANTED | B_BUSY | - B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF); + BUF_UNLOCK(bp); + bp->b_flags &= ~(B_ORDERED | B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF); splx(s); } @@ -981,6 +997,13 @@ bqrelse(struct buf * bp) if (bp->b_qindex != QUEUE_NONE) panic("bqrelse: free buffer onto another queue???"); #endif + if (BUF_REFCNT(bp) > 1) { + /* do not release to free list */ + panic("bqrelse: multiple refs"); + BUF_UNLOCK(bp); + splx(s); + return; + } if (bp->b_flags & B_LOCKED) { bp->b_flags &= ~B_ERROR; bp->b_qindex = QUEUE_LOCKED; @@ -1005,15 +1028,9 @@ bqrelse(struct buf * bp) if (bp->b_bufsize) bufspacewakeup(); - /* anyone need this block? */ - if (bp->b_flags & B_WANTED) { - bp->b_flags &= ~(B_WANTED | B_AGE); - wakeup(bp); - } - /* unlock */ - bp->b_flags &= ~(B_ORDERED | B_WANTED | B_BUSY | - B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF); + BUF_UNLOCK(bp); + bp->b_flags &= ~(B_ORDERED | B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF); splx(s); } @@ -1124,7 +1141,8 @@ vfs_bio_awrite(struct buf * bp) for (i = 1; i < maxcl; i++) { if ((bpa = gbincore(vp, lblkno + i)) && - ((bpa->b_flags & (B_BUSY | B_DELWRI | B_CLUSTEROK | B_INVAL)) == + BUF_REFCNT(bpa) == 0 && + ((bpa->b_flags & (B_DELWRI | B_CLUSTEROK | B_INVAL)) == (B_DELWRI | B_CLUSTEROK)) && (bpa->b_bufsize == size)) { if ((bpa->b_blkno == bpa->b_lblkno) || @@ -1145,8 +1163,9 @@ vfs_bio_awrite(struct buf * bp) } } + BUF_LOCK(bp, LK_EXCLUSIVE); bremfree(bp); - bp->b_flags |= B_BUSY | B_ASYNC; + bp->b_flags |= B_ASYNC; splx(s); /* @@ -1281,7 +1300,7 @@ restart: /* * Sanity Checks */ - KASSERT(!(bp->b_flags & B_BUSY), ("getnewbuf: busy buffer %p on free list", bp)); + KASSERT(BUF_REFCNT(bp) == 0, ("getnewbuf: busy buffer %p on free list", bp)); KASSERT(bp->b_qindex == qindex, ("getnewbuf: inconsistant queue %d bp %p", qindex, bp)); /* @@ -1374,8 +1393,9 @@ restart: * remains valid only for QUEUE_EMPTY bp's. */ + if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT) != 0) + panic("getnewbuf: locked buf"); bremfree(bp); - bp->b_flags |= B_BUSY; if (qindex == QUEUE_LRU || qindex == QUEUE_AGE) { if (bp->b_flags & B_VMIO) { @@ -1386,11 +1406,6 @@ restart: brelvp(bp); } - if (bp->b_flags & B_WANTED) { - bp->b_flags &= ~B_WANTED; - wakeup(bp); - } - /* * NOTE: nbp is now entirely invalid. We can only restart * the scan from this point on. @@ -1416,7 +1431,7 @@ restart: if (bp->b_bufsize) allocbuf(bp, 0); - bp->b_flags = B_BUSY; + bp->b_flags = 0; bp->b_dev = NODEV; bp->b_vp = NULL; bp->b_blkno = bp->b_lblkno = 0; @@ -1644,8 +1659,9 @@ flushbufqueues(void) */ if ((bp->b_flags & B_DELWRI) != 0) { if (bp->b_flags & B_INVAL) { + if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT) != 0) + panic("flushbufqueues: locked buf"); bremfree(bp); - bp->b_flags |= B_BUSY; brelse(bp); } else { vfs_bio_awrite(bp); @@ -1872,30 +1888,25 @@ loop: * Buffer is in-core */ - if (bp->b_flags & B_BUSY) { - bp->b_flags |= B_WANTED; + if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT)) { if (bp->b_usecount < BUF_MAXUSE) ++bp->b_usecount; - - if (!tsleep(bp, - (PRIBIO + 4) | slpflag, "getblk", slptimeo)) { + if (BUF_TIMELOCK(bp, LK_EXCLUSIVE | LK_SLEEPFAIL, + "getblk", slpflag, slptimeo) == ENOLCK) goto loop; - } - splx(s); return (struct buf *) NULL; } /* - * Busy the buffer. B_CACHE is cleared if the buffer is + * The buffer is locked. B_CACHE is cleared if the buffer is * invalid. Ohterwise, for a non-VMIO buffer, B_CACHE is set * and for a VMIO buffer B_CACHE is adjusted according to the * backing VM cache. */ - bp->b_flags |= B_BUSY; if (bp->b_flags & B_INVAL) bp->b_flags &= ~B_CACHE; - else if ((bp->b_flags & (B_VMIO|B_INVAL)) == 0) + else if ((bp->b_flags & (B_VMIO | B_INVAL)) == 0) bp->b_flags |= B_CACHE; bremfree(bp); @@ -1965,9 +1976,8 @@ loop: } else { /* * Buffer is not in-core, create new buffer. The buffer - * returned by getnewbuf() is marked B_BUSY. Note that the - * returned buffer is also considered valid ( not marked - * B_INVAL ). + * returned by getnewbuf() is locked. Note that the returned + * buffer is also considered valid (not marked B_INVAL). */ int bsize, maxsize, vmio; off_t offset; @@ -2088,7 +2098,7 @@ allocbuf(struct buf *bp, int size) int i; #if !defined(MAX_PERF) - if (!(bp->b_flags & B_BUSY)) + if (BUF_REFCNT(bp) == 0) panic("allocbuf: buffer not busy"); if (bp->b_kvasize < size) @@ -2376,7 +2386,7 @@ allocbuf(struct buf *bp, int size) * biowait: * * Wait for buffer I/O completion, returning error status. The buffer - * is left B_BUSY|B_DONE on return. B_EINTR is converted into a EINTR + * is left locked and B_DONE on return. B_EINTR is converted into a EINTR * error and cleared. */ int @@ -2432,7 +2442,7 @@ biodone(register struct buf * bp) s = splbio(); - KASSERT((bp->b_flags & B_BUSY), ("biodone: bp %p not busy", bp)); + KASSERT(BUF_REFCNT(bp) > 0, ("biodone: bp %p not busy", bp)); KASSERT(!(bp->b_flags & B_DONE), ("biodone: bp %p already done", bp)); bp->b_flags |= B_DONE; @@ -2583,8 +2593,8 @@ biodone(register struct buf * bp) } /* * For asynchronous completions, release the buffer now. The brelse - * checks for B_WANTED and will do the wakeup there if necessary - so - * no need to do a wakeup here in the async case. + * will do a wakeup there if necessary - so no need to do a wakeup + * here in the async case. The sync case always needs to do a wakeup. */ if (bp->b_flags & B_ASYNC) { @@ -2593,7 +2603,6 @@ biodone(register struct buf * bp) else bqrelse(bp); } else { - bp->b_flags &= ~B_WANTED; wakeup(bp); } splx(s); |