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authorLachlan McIlroy <lachlan@sgi.com>2008-08-13 15:42:10 +1000
committerLachlan McIlroy <lachlan@redback.melbourne.sgi.com>2008-08-13 15:42:10 +1000
commit3790689fa3c771bba6bafb7dee3e8389dd0b55bc (patch)
tree1445885f92de7f14034f4f5a647ea3e5ea6b43d8 /fs/xfs/linux-2.6/xfs_buf.c
parent79071eb0b2f142b9cc6531d04fa2915943938b5e (diff)
[XFS] Do not access buffers after dropping reference count
We should not access a buffer after dropping it's reference count otherwise we could race with another thread that releases the final reference count and frees the buffer causing us to access potentially unmapped memory. The bug this change fixes only occured on DEBUG XFS since the offending code was in an ASSERT. SGI-PV: 984429 SGI-Modid: xfs-linux-melb:xfs-kern:31715a Signed-off-by: Lachlan McIlroy <lachlan@sgi.com> Signed-off-by: David Chinner <david@fromorbit.com>
Diffstat (limited to 'fs/xfs/linux-2.6/xfs_buf.c')
-rw-r--r--fs/xfs/linux-2.6/xfs_buf.c6
1 files changed, 1 insertions, 5 deletions
diff --git a/fs/xfs/linux-2.6/xfs_buf.c b/fs/xfs/linux-2.6/xfs_buf.c
index 9cc8f0213095..9f45c74f1a84 100644
--- a/fs/xfs/linux-2.6/xfs_buf.c
+++ b/fs/xfs/linux-2.6/xfs_buf.c
@@ -838,6 +838,7 @@ xfs_buf_rele(
return;
}
+ ASSERT(atomic_read(&bp->b_hold) > 0);
if (atomic_dec_and_lock(&bp->b_hold, &hash->bh_lock)) {
if (bp->b_relse) {
atomic_inc(&bp->b_hold);
@@ -851,11 +852,6 @@ xfs_buf_rele(
spin_unlock(&hash->bh_lock);
xfs_buf_free(bp);
}
- } else {
- /*
- * Catch reference count leaks
- */
- ASSERT(atomic_read(&bp->b_hold) >= 0);
}
}