From f00c9e44ad1a9660fe8cd3ca15b6cd9497172eab Mon Sep 17 00:00:00 2001 From: Jan Kara Date: Wed, 15 Sep 2010 17:38:58 +0200 Subject: quota: Fix deadlock during path resolution As Al Viro pointed out path resolution during Q_QUOTAON calls to quotactl is prone to deadlocks. We hold s_umount semaphore for reading during the path resolution and resolution itself may need to acquire the semaphore for writing when e. g. autofs mountpoint is passed. Solve the problem by performing the resolution before we get hold of the superblock (and thus s_umount semaphore). The whole thing is complicated by the fact that some filesystems (OCFS2) ignore the path argument. So to distinguish between filesystem which want the path and which do not we introduce new .quota_on_meta callback which does not get the path. OCFS2 then uses this callback instead of old .quota_on. CC: Al Viro CC: Christoph Hellwig CC: Ted Ts'o CC: Joel Becker Signed-off-by: Jan Kara --- fs/ext4/super.c | 25 +++++++------------------ 1 file changed, 7 insertions(+), 18 deletions(-) (limited to 'fs/ext4') diff --git a/fs/ext4/super.c b/fs/ext4/super.c index 29c80f6d8b27..0f10ccd6bfc0 100644 --- a/fs/ext4/super.c +++ b/fs/ext4/super.c @@ -1162,7 +1162,7 @@ static int ext4_release_dquot(struct dquot *dquot); static int ext4_mark_dquot_dirty(struct dquot *dquot); static int ext4_write_info(struct super_block *sb, int type); static int ext4_quota_on(struct super_block *sb, int type, int format_id, - char *path); + struct path *path); static int ext4_quota_off(struct super_block *sb, int type); static int ext4_quota_on_mount(struct super_block *sb, int type); static ssize_t ext4_quota_read(struct super_block *sb, int type, char *data, @@ -4566,27 +4566,20 @@ static int ext4_quota_on_mount(struct super_block *sb, int type) * Standard function to be called on quota_on */ static int ext4_quota_on(struct super_block *sb, int type, int format_id, - char *name) + struct path *path) { int err; - struct path path; if (!test_opt(sb, QUOTA)) return -EINVAL; - err = kern_path(name, LOOKUP_FOLLOW, &path); - if (err) - return err; - /* Quotafile not on the same filesystem? */ - if (path.mnt->mnt_sb != sb) { - path_put(&path); + if (path->mnt->mnt_sb != sb) return -EXDEV; - } /* Journaling quota? */ if (EXT4_SB(sb)->s_qf_names[type]) { /* Quotafile not in fs root? */ - if (path.dentry->d_parent != sb->s_root) + if (path->dentry->d_parent != sb->s_root) ext4_msg(sb, KERN_WARNING, "Quota file not on filesystem root. " "Journaled quota will not work"); @@ -4597,7 +4590,7 @@ static int ext4_quota_on(struct super_block *sb, int type, int format_id, * all updates to the file when we bypass pagecache... */ if (EXT4_SB(sb)->s_journal && - ext4_should_journal_data(path.dentry->d_inode)) { + ext4_should_journal_data(path->dentry->d_inode)) { /* * We don't need to lock updates but journal_flush() could * otherwise be livelocked... @@ -4605,15 +4598,11 @@ static int ext4_quota_on(struct super_block *sb, int type, int format_id, jbd2_journal_lock_updates(EXT4_SB(sb)->s_journal); err = jbd2_journal_flush(EXT4_SB(sb)->s_journal); jbd2_journal_unlock_updates(EXT4_SB(sb)->s_journal); - if (err) { - path_put(&path); + if (err) return err; - } } - err = dquot_quota_on_path(sb, type, format_id, &path); - path_put(&path); - return err; + return dquot_quota_on(sb, type, format_id, path); } static int ext4_quota_off(struct super_block *sb, int type) -- cgit v1.2.3