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Fix a bug reported by pho@ where one can induce a panic by decreasing

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vfs.ufs.dirhash_maxmem below the current amount of memory used by dirhash. When
ufsdirhash_build() is called with the memory in use greater than dirhash_maxmem,
it attempts to free up memory by calling ufsdirhash_recycle(). If successful in
freeing enough memory, ufsdirhash_recycle() leaves the dirhash list locked. But
at this point in ufsdirhash_build(), the list is not explicitly unlocked after
the call(s) to ufsdirhash_recycle(). When we next attempt to lock the dirhash
list, we will get a "panic: _mtx_lock_sleep: recursed on non-recursive mutex
dirhash list".

Tested by:	pho
Approved by:	dwmalone (mentor)
MFC after:	3 weeks
This commit is contained in:
snb 2009-06-25 20:40:13 +00:00
parent 6d5618d67c
commit 5d2850ae03
1 changed files with 4 additions and 1 deletions
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5
sys/ufs/ufs/ufs_dirhash.c
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@ -348,9 +348,12 @@ ufsdirhash_build(struct inode *ip)
int dirblocks, i, j, memreqd, nblocks, narrays, nslots, slot;
/* Take care of a decreased sysctl value. */
while (ufs_dirhashmem > ufs_dirhashmaxmem)
while (ufs_dirhashmem > ufs_dirhashmaxmem) {
if (ufsdirhash_recycle(0) != 0)
return (-1);
/* Recycled enough memory, so unlock the list. */
DIRHASHLIST_UNLOCK();
}
/* Check if we can/should use dirhash. */
if (ip->i_size < ufs_mindirhashsize || OFSFMT(ip->i_vnode) ||