From 7925409e202a41176b729671eab6e610a54153cd Mon Sep 17 00:00:00 2001 From: Jan Kara Date: Wed, 16 May 2007 22:11:19 -0700 Subject: circular locking dependency found in QUOTA OFF i_mutex on quota files is special. Unlike i_mutexes for other inodes it is acquired under dqonoff_mutex. Tell lockdep about this lock ranking. Also comment and code in quota_sync_sb() seem to be bogus (as i_mutex for quota file can be acquired under dqonoff_mutex). Move truncate_inode_pages() call under dqonoff_mutex and save some problems with races... Signed-off-by: Jan Kara Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- fs/quota.c | 23 +++++++---------------- 1 file changed, 7 insertions(+), 16 deletions(-) (limited to 'fs/quota.c') diff --git a/fs/quota.c b/fs/quota.c index e9d88fd0eca8..9f237d6182c9 100644 --- a/fs/quota.c +++ b/fs/quota.c @@ -157,7 +157,6 @@ static int check_quotactl_valid(struct super_block *sb, int type, int cmd, qid_t static void quota_sync_sb(struct super_block *sb, int type) { int cnt; - struct inode *discard[MAXQUOTAS]; sb->s_qcop->quota_sync(sb, type); /* This is not very clever (and fast) but currently I don't know about @@ -167,29 +166,21 @@ static void quota_sync_sb(struct super_block *sb, int type) sb->s_op->sync_fs(sb, 1); sync_blockdev(sb->s_bdev); - /* Now when everything is written we can discard the pagecache so - * that userspace sees the changes. We need i_mutex and so we could - * not do it inside dqonoff_mutex. Moreover we need to be carefull - * about races with quotaoff() (that is the reason why we have own - * reference to inode). */ + /* + * Now when everything is written we can discard the pagecache so + * that userspace sees the changes. + */ mutex_lock(&sb_dqopt(sb)->dqonoff_mutex); for (cnt = 0; cnt < MAXQUOTAS; cnt++) { - discard[cnt] = NULL; if (type != -1 && cnt != type) continue; if (!sb_has_quota_enabled(sb, cnt)) continue; - discard[cnt] = igrab(sb_dqopt(sb)->files[cnt]); + mutex_lock_nested(&sb_dqopt(sb)->files[cnt]->i_mutex, I_MUTEX_QUOTA); + truncate_inode_pages(&sb_dqopt(sb)->files[cnt]->i_data, 0); + mutex_unlock(&sb_dqopt(sb)->files[cnt]->i_mutex); } mutex_unlock(&sb_dqopt(sb)->dqonoff_mutex); - for (cnt = 0; cnt < MAXQUOTAS; cnt++) { - if (discard[cnt]) { - mutex_lock(&discard[cnt]->i_mutex); - truncate_inode_pages(&discard[cnt]->i_data, 0); - mutex_unlock(&discard[cnt]->i_mutex); - iput(discard[cnt]); - } - } } void sync_dquots(struct super_block *sb, int type) -- cgit v1.2.3