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authorJeff Mahoney <jeffm@suse.com>2012-08-02 21:36:04 -0400
committerJan Kara <jack@suse.cz>2012-08-15 00:22:57 +0200
commit48d1788493f874e5d32dccb2911a7bc91c248b4b (patch)
treec03aa75bc4143380e177555fb32acff6126ff782 /fs/reiserfs
parent6ea2eea1fa930b9308a06f77fce65c38931eeb13 (diff)
downloadop-kernel-dev-48d1788493f874e5d32dccb2911a7bc91c248b4b.zip
op-kernel-dev-48d1788493f874e5d32dccb2911a7bc91c248b4b.tar.gz
reiserfs: fix deadlocks with quotas
The BKL push-down for reiserfs made lock recursion a special case that needs to be handled explicitly. One of the cases that was unhandled is dropping the quota during inode eviction. Both reiserfs_evict_inode and reiserfs_write_dquot take the write lock, but when the journal lock is taken it only drops one the references. The locking rules are that the journal lock be acquired before the write lock so leaving the reference open leads to a ABBA deadlock. This patch pushes the unlock up before clear_inode and avoids the recursive locking. Another ABBA situation can occur when the write lock is dropped while reading the bitmap buffer while in the quota code. When the lock is reacquired, it will deadlock against dquot->dq_lock and dqopt->dqio_mutex in the dquot_acquire path. It's safe to retain the lock across the read and should be cached under write load. Signed-off-by: Jeff Mahoney <jeffm@suse.com> Signed-off-by: Jan Kara <jack@suse.cz>
Diffstat (limited to 'fs/reiserfs')
-rw-r--r--fs/reiserfs/bitmap.c2
-rw-r--r--fs/reiserfs/inode.c2
2 files changed, 1 insertions, 3 deletions
diff --git a/fs/reiserfs/bitmap.c b/fs/reiserfs/bitmap.c
index 4c0c7d1..a98b774 100644
--- a/fs/reiserfs/bitmap.c
+++ b/fs/reiserfs/bitmap.c
@@ -1334,9 +1334,7 @@ struct buffer_head *reiserfs_read_bitmap_block(struct super_block *sb,
else if (bitmap == 0)
block = (REISERFS_DISK_OFFSET_IN_BYTES >> sb->s_blocksize_bits) + 1;
- reiserfs_write_unlock(sb);
bh = sb_bread(sb, block);
- reiserfs_write_lock(sb);
if (bh == NULL)
reiserfs_warning(sb, "sh-2029: %s: bitmap block (#%u) "
"reading failed", __func__, block);
diff --git a/fs/reiserfs/inode.c b/fs/reiserfs/inode.c
index a6d4268..855da58 100644
--- a/fs/reiserfs/inode.c
+++ b/fs/reiserfs/inode.c
@@ -76,10 +76,10 @@ void reiserfs_evict_inode(struct inode *inode)
;
}
out:
+ reiserfs_write_unlock_once(inode->i_sb, depth);
clear_inode(inode); /* note this must go after the journal_end to prevent deadlock */
dquot_drop(inode);
inode->i_blocks = 0;
- reiserfs_write_unlock_once(inode->i_sb, depth);
return;
no_delete:
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