1 From: Jan Kara <jack@suse.cz>
2 Subject: ocfs2: Fix lock inversion in ocfs2_local_read_info()
5 This function is called with dqio_mutex held but it has to acquire lock
6 from global quota file which ranks above this lock. This is not deadlockable
7 lock inversion since this code path is take only during mount when noone
8 else can race with us but let's clean this up to silence lockdep.
10 We just drop the dqio_mutex in the beginning of the function and reacquire
11 it in the end since we don't need it - noone can race with us at this moment.
13 Signed-off-by: Jan Kara <jack@suse.cz>
15 fs/ocfs2/quota_local.c | 5 +++++
16 1 files changed, 5 insertions(+), 0 deletions(-)
18 diff --git a/fs/ocfs2/quota_local.c b/fs/ocfs2/quota_local.c
19 index 07deec5..71cf410 100644
20 --- a/fs/ocfs2/quota_local.c
21 +++ b/fs/ocfs2/quota_local.c
22 @@ -655,6 +655,9 @@ static int ocfs2_local_read_info(struct super_block *sb, int type)
23 struct ocfs2_quota_recovery *rec;
26 + /* We don't need the lock and we have to acquire quota file locks
27 + * which will later depend on this lock */
28 + mutex_unlock(&sb_dqopt(sb)->dqio_mutex);
29 info->dqi_maxblimit = 0x7fffffffffffffffLL;
30 info->dqi_maxilimit = 0x7fffffffffffffffLL;
31 oinfo = kmalloc(sizeof(struct ocfs2_mem_dqinfo), GFP_NOFS);
32 @@ -733,6 +736,7 @@ static int ocfs2_local_read_info(struct super_block *sb, int type)
36 + mutex_lock(&sb_dqopt(sb)->dqio_mutex);
40 @@ -746,6 +750,7 @@ out_err:
44 + mutex_lock(&sb_dqopt(sb)->dqio_mutex);