Merge branch 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs-2.6

* 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs-2.6:
  quota: Fix deadlock during path resolution

fs/ext3/super.c

@@ -754,7 +754,7 @@ static int ext3_release_dquot(struct dquot *dquot);
 static int ext3_mark_dquot_dirty(struct dquot *dquot);
 static int ext3_write_info(struct super_block *sb, int type);
 static int ext3_quota_on(struct super_block *sb, int type, int format_id,
-				char *path);
+			 struct path *path);
 static int ext3_quota_on_mount(struct super_block *sb, int type);
 static ssize_t ext3_quota_read(struct super_block *sb, int type, char *data,
 			       size_t len, loff_t off);
@@ -2877,27 +2877,20 @@ static int ext3_quota_on_mount(struct super_block *sb, int type)
  * Standard function to be called on quota_on
  */
 static int ext3_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 (EXT3_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)
 			ext3_msg(sb, KERN_WARNING,
 				"warning: Quota file not on filesystem root. "
 				"Journaled quota will not work.");
@@ -2907,7 +2900,7 @@ static int ext3_quota_on(struct super_block *sb, int type, int format_id,
 	 * When we journal data on quota file, we have to flush journal to see
 	 * all updates to the file when we bypass pagecache...
 	 */
-	if (ext3_should_journal_data(path.dentry->d_inode)) {
+	if (ext3_should_journal_data(path->dentry->d_inode)) {
 		/*
 		 * We don't need to lock updates but journal_flush() could
 		 * otherwise be livelocked...
@@ -2915,15 +2908,11 @@ static int ext3_quota_on(struct super_block *sb, int type, int format_id,
 		journal_lock_updates(EXT3_SB(sb)->s_journal);
 		err = journal_flush(EXT3_SB(sb)->s_journal);
 		journal_unlock_updates(EXT3_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);
 }
 
 /* Read data from quotafile - avoid pagecache and such because we cannot afford

fs/ext4/super.c

@@ -1161,7 +1161,7 @@ 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,
@@ -4558,27 +4558,20 @@ 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");
@@ -4589,7 +4582,7 @@ 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...
@@ -4597,15 +4590,11 @@ 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)

fs/ocfs2/super.c

@@ -993,8 +993,7 @@ static void ocfs2_disable_quotas(struct ocfs2_super *osb)
 }
 
 /* Handle quota on quotactl */
-static int ocfs2_quota_on(struct super_block *sb, int type, int format_id,
-			  char *path)
+static int ocfs2_quota_on(struct super_block *sb, int type, int format_id)
 {
 	unsigned int feature[MAXQUOTAS] = { OCFS2_FEATURE_RO_COMPAT_USRQUOTA,
 					     OCFS2_FEATURE_RO_COMPAT_GRPQUOTA};
@@ -1013,7 +1012,7 @@ static int ocfs2_quota_off(struct super_block *sb, int type)
 }
 
 static const struct quotactl_ops ocfs2_quotactl_ops = {
-	.quota_on	= ocfs2_quota_on,
+	.quota_on_meta	= ocfs2_quota_on,
 	.quota_off	= ocfs2_quota_off,
 	.quota_sync	= dquot_quota_sync,
 	.get_info	= dquot_get_dqinfo,

fs/quota/dquot.c

@@ -2189,8 +2189,8 @@ int dquot_resume(struct super_block *sb, int type)
 }
 EXPORT_SYMBOL(dquot_resume);
 
-int dquot_quota_on_path(struct super_block *sb, int type, int format_id,
-		      struct path *path)
+int dquot_quota_on(struct super_block *sb, int type, int format_id,
+		   struct path *path)
 {
 	int error = security_quota_on(path->dentry);
 	if (error)
@@ -2204,20 +2204,6 @@ int dquot_quota_on_path(struct super_block *sb, int type, int format_id,
 					     DQUOT_LIMITS_ENABLED);
 	return error;
 }
-EXPORT_SYMBOL(dquot_quota_on_path);
-
-int dquot_quota_on(struct super_block *sb, int type, int format_id, char *name)
-{
-	struct path path;
-	int error;
-
-	error = kern_path(name, LOOKUP_FOLLOW, &path);
-	if (!error) {
-		error = dquot_quota_on_path(sb, type, format_id, &path);
-		path_put(&path);
-	}
-	return error;
-}
 EXPORT_SYMBOL(dquot_quota_on);
 
 /*

fs/quota/quota.c

@@ -64,18 +64,15 @@ static int quota_sync_all(int type)
 }
 
 static int quota_quotaon(struct super_block *sb, int type, int cmd, qid_t id,
-		         void __user *addr)
+		         struct path *path)
 {
-	char *pathname;
-	int ret = -ENOSYS;
-
-	pathname = getname(addr);
-	if (IS_ERR(pathname))
-		return PTR_ERR(pathname);
-	if (sb->s_qcop->quota_on)
-		ret = sb->s_qcop->quota_on(sb, type, id, pathname);
-	putname(pathname);
-	return ret;
+	if (!sb->s_qcop->quota_on && !sb->s_qcop->quota_on_meta)
+		return -ENOSYS;
+	if (sb->s_qcop->quota_on_meta)
+		return sb->s_qcop->quota_on_meta(sb, type, id);
+	if (IS_ERR(path))
+		return PTR_ERR(path);
+	return sb->s_qcop->quota_on(sb, type, id, path);
 }
 
 static int quota_getfmt(struct super_block *sb, int type, void __user *addr)
@@ -241,7 +238,7 @@ static int quota_getxquota(struct super_block *sb, int type, qid_t id,
 
 /* Copy parameters and call proper function */
 static int do_quotactl(struct super_block *sb, int type, int cmd, qid_t id,
-		       void __user *addr)
+		       void __user *addr, struct path *path)
 {
 	int ret;
 
@@ -256,7 +253,7 @@ static int do_quotactl(struct super_block *sb, int type, int cmd, qid_t id,
 
 	switch (cmd) {
 	case Q_QUOTAON:
-		return quota_quotaon(sb, type, cmd, id, addr);
+		return quota_quotaon(sb, type, cmd, id, path);
 	case Q_QUOTAOFF:
 		if (!sb->s_qcop->quota_off)
 			return -ENOSYS;
@@ -335,6 +332,7 @@ SYSCALL_DEFINE4(quotactl, unsigned int, cmd, const char __user *, special,
 {
 	uint cmds, type;
 	struct super_block *sb = NULL;
+	struct path path, *pathp = NULL;
 	int ret;
 
 	cmds = cmd >> SUBCMDSHIFT;
@@ -351,12 +349,27 @@ SYSCALL_DEFINE4(quotactl, unsigned int, cmd, const char __user *, special,
 		return -ENODEV;
 	}
 
+	/*
+	 * Path for quotaon has to be resolved before grabbing superblock
+	 * because that gets s_umount sem which is also possibly needed by path
+	 * resolution (think about autofs) and thus deadlocks could arise.
+	 */
+	if (cmds == Q_QUOTAON) {
+		ret = user_path_at(AT_FDCWD, addr, LOOKUP_FOLLOW, &path);
+		if (ret)
+			pathp = ERR_PTR(ret);
+		else
+			pathp = &path;
+	}
+
 	sb = quotactl_block(special);
 	if (IS_ERR(sb))
 		return PTR_ERR(sb);
 
-	ret = do_quotactl(sb, type, cmds, id, addr);
+	ret = do_quotactl(sb, type, cmds, id, addr, pathp);
 
 	drop_super(sb);
+	if (pathp && !IS_ERR(pathp))
+		path_put(pathp);
 	return ret;
 }

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;
 }
 

include/linux/quota.h

@@ -322,9 +322,12 @@ struct dquot_operations {
 	qsize_t *(*get_reserved_space) (struct inode *);
 };
 
+struct path;
+
 /* Operations handling requests from userspace */
 struct quotactl_ops {
-	int (*quota_on)(struct super_block *, int, int, char *);
+	int (*quota_on)(struct super_block *, int, int, struct path *);
+	int (*quota_on_meta)(struct super_block *, int, int);
 	int (*quota_off)(struct super_block *, int);
 	int (*quota_sync)(struct super_block *, int, int);
 	int (*get_info)(struct super_block *, int, struct if_dqinfo *);

include/linux/quotaops.h

@@ -76,11 +76,9 @@ int dquot_mark_dquot_dirty(struct dquot *dquot);
 
 int dquot_file_open(struct inode *inode, struct file *file);
 
-int dquot_quota_on(struct super_block *sb, int type, int format_id,
-	char *path);
 int dquot_enable(struct inode *inode, int type, int format_id,
 	unsigned int flags);
-int dquot_quota_on_path(struct super_block *sb, int type, int format_id,
+int dquot_quota_on(struct super_block *sb, int type, int format_id,
  	struct path *path);
 int dquot_quota_on_mount(struct super_block *sb, char *qf_name,
  	int format_id, int type);