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| author | Jan Kara <jack@suse.cz> | 2007-05-17 07:11:19 +0200 |
|---|---|---|
| committer | Linus Torvalds <torvalds@woody.linux-foundation.org> | 2007-05-17 14:23:05 +0200 |
| commit | 7925409e202a41176b729671eab6e610a54153cd (patch) | |
| tree | 7b97858fa33169a1616cc6f1e05b66117e97c1b3 /fs/quota.c | |
| parent | i386: don't check_pgt_cache in flush_tlb_mm (diff) | |
| download | linux-7925409e202a41176b729671eab6e610a54153cd.tar.xz linux-7925409e202a41176b729671eab6e610a54153cd.zip | |
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 <jack@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to '')
| -rw-r--r-- | fs/quota.c | 23 |
1 files changed, 7 insertions, 16 deletions
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) |