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author | Arjan van de Ven <arjan@linux.intel.com> | 2006-07-03 00:25:20 -0700 |
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committer | Linus Torvalds <torvalds@g5.osdl.org> | 2006-07-03 15:27:08 -0700 |
commit | 5c81a4197de38411fe3e27f8593fff73a5d6b868 (patch) | |
tree | 0a7867025e08353bf9946759864beeaf0ff01ad2 /fs/reiserfs/super.c | |
parent | 59345374742ee6673c2d04b0fa8c888e881b7209 (diff) | |
download | linux-5c81a4197de38411fe3e27f8593fff73a5d6b868.tar.bz2 |
[PATCH] lockdep: annotate the quota code
The quota code plays interesting games with the lock ordering; to quote Jan:
| i_mutex of inode containing quota file is acquired after all other
| quota locks. i_mutex of all other inodes is acquired before quota
| locks. Quota code makes sure (by resetting inode operations and
| setting special flag on inode) that noone tries to enter quota code
| while holding i_mutex on a quota file...
The good news is that all of this special case i_mutex grabbing happens in the
(per filesystem) low level quota write function. For this special case we
need a new I_MUTEX_* nesting level, since this just entirely outside any of
the regular VFS locking rules for i_mutex. I trust Jan on his blue eyes that
this is not ever going to deadlock; and based on that the patch below is what
it takes to inform lockdep of these very interesting new locking rules.
The new locking rule for the I_MUTEX_QUOTA nesting level is that this is the
deepest possible level of nesting for i_mutex, and that this only should be
used in quota write (and possibly read) function of filesystems. This makes
the lock ordering of the I_MUTEX_* levels:
I_MUTEX_PARENT -> I_MUTEX_CHILD -> I_MUTEX_NORMAL -> I_MUTEX_QUOTA
Has no effect on non-lockdep kernels.
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Acked-by: Ingo Molnar <mingo@elte.hu>
Cc: Jan Kara <jack@ucw.cz>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'fs/reiserfs/super.c')
-rw-r--r-- | fs/reiserfs/super.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/fs/reiserfs/super.c b/fs/reiserfs/super.c index 28eb3c886034..5567328f1041 100644 --- a/fs/reiserfs/super.c +++ b/fs/reiserfs/super.c @@ -2203,7 +2203,7 @@ static ssize_t reiserfs_quota_write(struct super_block *sb, int type, size_t towrite = len; struct buffer_head tmp_bh, *bh; - mutex_lock(&inode->i_mutex); + mutex_lock_nested(&inode->i_mutex, I_MUTEX_QUOTA); while (towrite > 0) { tocopy = sb->s_blocksize - offset < towrite ? sb->s_blocksize - offset : towrite; |