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The buffers b_vflags field is not always properly protected by

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bufobj lock. If b_bufobj is not NULL, then bufobj lock should be
held when manipulating the flags. Not doing this sometimes leaves
BV_BKGRDINPROG to be erronously set, causing softdep' getdirtybuf() to
stuck indefinitely in "getbuf" sleep, waiting for background write to
finish which is not actually performed.

Add BO_LOCK() in the cases where it was missed.

In collaboration with:	pho
Tested by:	bz
Reviewed by:	jeff
MFC after:	1 month
This commit is contained in:
Konstantin Belousov 2010-08-12 08:36:23 +00:00
parent 691401eef8
commit 3beb1b723f
2 changed files with 59 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

53
sys/kern/vfs_bio.c
View File

@ -398,6 +398,8 @@ bufcountwakeup(struct buf *bp)
KASSERT((bp->b_vflags & BV_INFREECNT) == 0,
("buf %p already counted as free", bp));
if (bp->b_bufobj != NULL)
mtx_assert(BO_MTX(bp->b_bufobj), MA_OWNED);
bp->b_vflags |= BV_INFREECNT;
old = atomic_fetchadd_int(&numfreebuffers, 1);
KASSERT(old >= 0 && old < nbuf,
@ -714,6 +716,8 @@ bremfree(struct buf *bp)
if ((bp->b_flags & B_INVAL) || (bp->b_flags & B_DELWRI) == 0) {
KASSERT((bp->b_vflags & BV_INFREECNT) != 0,
("buf %p not counted in numfreebuffers", bp));
if (bp->b_bufobj != NULL)
mtx_assert(BO_MTX(bp->b_bufobj), MA_OWNED);
bp->b_vflags &= ~BV_INFREECNT;
old = atomic_fetchadd_int(&numfreebuffers, -1);
KASSERT(old > 0, ("numfreebuffers dropped to %d", old - 1));
@ -770,6 +774,8 @@ bremfreel(struct buf *bp)
if ((bp->b_flags & B_INVAL) || (bp->b_flags & B_DELWRI) == 0) {
KASSERT((bp->b_vflags & BV_INFREECNT) != 0,
("buf %p not counted in numfreebuffers", bp));
if (bp->b_bufobj != NULL)
mtx_assert(BO_MTX(bp->b_bufobj), MA_OWNED);
bp->b_vflags &= ~BV_INFREECNT;
old = atomic_fetchadd_int(&numfreebuffers, -1);
KASSERT(old > 0, ("numfreebuffers dropped to %d", old - 1));
@ -1412,8 +1418,16 @@ brelse(struct buf *bp)
/* enqueue */
mtx_lock(&bqlock);
/* Handle delayed bremfree() processing. */
if (bp->b_flags & B_REMFREE)
if (bp->b_flags & B_REMFREE) {
struct bufobj *bo;
bo = bp->b_bufobj;
if (bo != NULL)
BO_LOCK(bo);
bremfreel(bp);
if (bo != NULL)
BO_UNLOCK(bo);
}
if (bp->b_qindex != QUEUE_NONE)
panic("brelse: free buffer onto another queue???");
@ -1474,8 +1488,16 @@ brelse(struct buf *bp)
* if B_INVAL is set ).
*/
if (!(bp->b_flags & B_DELWRI))
if (!(bp->b_flags & B_DELWRI)) {
struct bufobj *bo;
bo = bp->b_bufobj;
if (bo != NULL)
BO_LOCK(bo);
bufcountwakeup(bp);
if (bo != NULL)
BO_UNLOCK(bo);
}
/*
* Something we can maybe free or reuse
@ -1504,6 +1526,8 @@ brelse(struct buf *bp)
void
bqrelse(struct buf *bp)
{
struct bufobj *bo;
CTR3(KTR_BUF, "bqrelse(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)),
("bqrelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp));
@ -1514,10 +1538,15 @@ bqrelse(struct buf *bp)
return;
}
bo = bp->b_bufobj;
if (bp->b_flags & B_MANAGED) {
if (bp->b_flags & B_REMFREE) {
mtx_lock(&bqlock);
if (bo != NULL)
BO_LOCK(bo);
bremfreel(bp);
if (bo != NULL)
BO_UNLOCK(bo);
mtx_unlock(&bqlock);
}
bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF);
@ -1527,8 +1556,13 @@ bqrelse(struct buf *bp)
mtx_lock(&bqlock);
/* Handle delayed bremfree() processing. */
if (bp->b_flags & B_REMFREE)
if (bp->b_flags & B_REMFREE) {
if (bo != NULL)
BO_LOCK(bo);
bremfreel(bp);
if (bo != NULL)
BO_UNLOCK(bo);
}
if (bp->b_qindex != QUEUE_NONE)
panic("bqrelse: free buffer onto another queue???");
/* buffers with stale but valid contents */
@ -1563,8 +1597,13 @@ bqrelse(struct buf *bp)
}
mtx_unlock(&bqlock);
if ((bp->b_flags & B_INVAL) || !(bp->b_flags & B_DELWRI))
if ((bp->b_flags & B_INVAL) || !(bp->b_flags & B_DELWRI)) {
if (bo != NULL)
BO_LOCK(bo);
bufcountwakeup(bp);
if (bo != NULL)
BO_UNLOCK(bo);
}
/*
* Something we can maybe free or reuse.
@ -1898,7 +1937,11 @@ getnewbuf(struct vnode *vp, int slpflag, int slptimeo, int size, int maxsize,
KASSERT((bp->b_flags & B_DELWRI) == 0, ("delwri buffer %p found in queue %d", bp, qindex));
if (bp->b_bufobj != NULL)
BO_LOCK(bp->b_bufobj);
bremfreel(bp);
if (bp->b_bufobj != NULL)
BO_UNLOCK(bp->b_bufobj);
mtx_unlock(&bqlock);
if (qindex == QUEUE_CLEAN) {
@ -2635,7 +2678,9 @@ getblk(struct vnode * vp, daddr_t blkno, int size, int slpflag, int slptimeo,
bp->b_flags &= ~B_CACHE;
else if ((bp->b_flags & (B_VMIO | B_INVAL)) == 0)
bp->b_flags |= B_CACHE;
BO_LOCK(bo);
bremfree(bp);
BO_UNLOCK(bo);
/*
* check for size inconsistancies for non-VMIO case.

10
sys/kern/vfs_subr.c
View File

@ -1260,13 +1260,17 @@ flushbuflist( struct bufv *bufv, int flags, struct bufobj *bo, int slpflag,
*/
if (((bp->b_flags & (B_DELWRI | B_INVAL)) == B_DELWRI) &&
(flags & V_SAVE)) {
BO_LOCK(bo);
bremfree(bp);
BO_UNLOCK(bo);
bp->b_flags |= B_ASYNC;
bwrite(bp);
BO_LOCK(bo);
return (EAGAIN); /* XXX: why not loop ? */
}
BO_LOCK(bo);
bremfree(bp);
BO_UNLOCK(bo);
bp->b_flags |= (B_INVAL | B_RELBUF);
bp->b_flags &= ~B_ASYNC;
brelse(bp);
@ -1318,7 +1322,9 @@ vtruncbuf(struct vnode *vp, struct ucred *cred, struct thread *td,
BO_MTX(bo)) == ENOLCK)
goto restart;
BO_LOCK(bo);
bremfree(bp);
BO_UNLOCK(bo);
bp->b_flags |= (B_INVAL | B_RELBUF);
bp->b_flags &= ~B_ASYNC;
brelse(bp);
@ -1340,7 +1346,9 @@ vtruncbuf(struct vnode *vp, struct ucred *cred, struct thread *td,
LK_EXCLUSIVE | LK_SLEEPFAIL | LK_INTERLOCK,
BO_MTX(bo)) == ENOLCK)
goto restart;
BO_LOCK(bo);
bremfree(bp);
BO_UNLOCK(bo);
bp->b_flags |= (B_INVAL | B_RELBUF);
bp->b_flags &= ~B_ASYNC;
brelse(bp);
@ -1372,7 +1380,9 @@ vtruncbuf(struct vnode *vp, struct ucred *cred, struct thread *td,
VNASSERT((bp->b_flags & B_DELWRI), vp,
("buf(%p) on dirty queue without DELWRI", bp));
BO_LOCK(bo);
bremfree(bp);
BO_UNLOCK(bo);
bawrite(bp);
BO_LOCK(bo);
goto restartsync;