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/reiserfs/super.c | 17 ++++++----------- 1 file changed, 6 insertions(+), 11 deletions(-) (limited to 'fs/reiserfs/super.c') diff --git a/fs/reiserfs/super.c b/fs/reiserfs/super.c index 2575682a9ead..0aab04f46827 100644 --- a/fs/reiserfs/super.c +++ b/fs/reiserfs/super.c @@ -632,7 +632,7 @@ static int reiserfs_acquire_dquot(struct dquot *); static int reiserfs_release_dquot(struct dquot *); static int reiserfs_mark_dquot_dirty(struct dquot *); static int reiserfs_write_info(struct super_block *, int); -static int reiserfs_quota_on(struct super_block *, int, int, char *); +static int reiserfs_quota_on(struct super_block *, int, int, struct path *); static const struct dquot_operations reiserfs_quota_operations = { .write_dquot = reiserfs_write_dquot, @@ -2048,25 +2048,21 @@ static int reiserfs_quota_on_mount(struct super_block *sb, int type) * Standard function to be called on quota_on */ static int reiserfs_quota_on(struct super_block *sb, int type, int format_id, - char *name) + struct path *path) { int err; - struct path path; struct inode *inode; struct reiserfs_transaction_handle th; if (!(REISERFS_SB(sb)->s_mount_opt & (1 << REISERFS_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) { + if (path->mnt->mnt_sb != sb) { err = -EXDEV; goto out; } - inode = path.dentry->d_inode; + inode = path->dentry->d_inode; /* We must not pack tails for quota files on reiserfs for quota IO to work */ if (!(REISERFS_I(inode)->i_flags & i_nopack_mask)) { err = reiserfs_unpack(inode, NULL); @@ -2082,7 +2078,7 @@ static int reiserfs_quota_on(struct super_block *sb, int type, int format_id, /* Journaling quota? */ if (REISERFS_SB(sb)->s_qf_names[type]) { /* Quotafile not of fs root? */ - if (path.dentry->d_parent != sb->s_root) + if (path->dentry->d_parent != sb->s_root) reiserfs_warning(sb, "super-6521", "Quota file not on filesystem root. " "Journalled quota will not work."); @@ -2101,9 +2097,8 @@ static int reiserfs_quota_on(struct super_block *sb, int type, int format_id, if (err) goto out; } - err = dquot_quota_on_path(sb, type, format_id, &path); + err = dquot_quota_on(sb, type, format_id, path); out: - path_put(&path); return err; } -- cgit v1.2.3