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If the lock passed to getdirtybuf() is the softdep lock then the background

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write completed wakeup could be missed.  Close the race by grabbing the lock
normally used for protection of bp->b_xflags.

Reviewed by:	truckman
This commit is contained in:
Tor Egge 2006-01-09 19:32:21 +00:00
parent c8c7711d66
commit 6c62b2acd0
1 changed files with 13 additions and 0 deletions
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13
sys/ufs/ffs/ffs_softdep.c
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@ -5901,6 +5901,19 @@ getdirtybuf(bp, mtx, waitfor)
return (NULL);
}
if ((bp->b_vflags & BV_BKGRDINPROG) != 0) {
if (mtx == &lk && waitfor == MNT_WAIT) {
mtx_unlock(mtx);
BO_LOCK(bp->b_bufobj);
BUF_UNLOCK(bp);
if ((bp->b_vflags & BV_BKGRDINPROG) != 0) {
bp->b_vflags |= BV_BKGRDWAIT;
msleep(&bp->b_xflags, BO_MTX(bp->b_bufobj),
PRIBIO | PDROP, "getbuf", 0);
} else
BO_UNLOCK(bp->b_bufobj);
mtx_lock(mtx);
return (NULL);
}
BUF_UNLOCK(bp);
if (waitfor != MNT_WAIT)
return (NULL);