ext4: Detect already used quota file early

When we try to use file already used as a quota file again (for the same or different quota type), strange things can happen. At the very least lockdep annotations may be wrong but also inode flags may be wrongly set / reset. When the file is used for two quota types at once we can even corrupt the file and likely crash the kernel. Catch all these cases by checking whether passed file is already used as quota file and bail early in that case. This fixes occasional generic/219 failure due to lockdep complaint. Reviewed-by: Andreas Dilger <[email protected]> Reported-by: Ritesh Harjani <[email protected]> Signed-off-by: Jan Kara <[email protected]> Link: https://lore.kernel.org/r/[email protected] Signed-off-by: Theodore Ts'o <[email protected]>
berg · Oct 18, 2020 · e0770e9 · e0770e9
1 parent fc750a3
commit e0770e9
Showing 1 changed file with 5 additions and 0 deletions.
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
@@ -6225,6 +6225,11 @@ static int ext4_quota_on(struct super_block *sb, int type, int format_id,
 	/* Quotafile not on the same filesystem? */
 	if (path->dentry->d_sb != sb)
 		return -EXDEV;
+
+	/* Quota already enabled for this file? */
+	if (IS_NOQUOTA(d_inode(path->dentry)))
+		return -EBUSY;
+
 	/* Journaling quota? */
 	if (EXT4_SB(sb)->s_qf_names[type]) {
 		/* Quotafile not in fs root? */