---

yaml
---
r: 107529
b: refs/heads/master
c: 8a26646
h: refs/heads/master
i:
  107527: 04b3b9a
v: v3

[refs]

@@ -1,2 +1,2 @@
 ---
-refs/heads/master: d03856bd5e5abac717da137dc60fe4a691769bd0
+refs/heads/master: 8a266467b8c4841ca994d0fe59f39e584650e3df

trunk/fs/ext4/super.c

@@ -1626,7 +1626,8 @@ static int ext4_check_descriptors(struct super_block *sb)
 			       "Checksum for group %lu failed (%u!=%u)\n",
 			       i, le16_to_cpu(ext4_group_desc_csum(sbi, i,
 			       gdp)), le16_to_cpu(gdp->bg_checksum));
-			return 0;
+			if (!(sb->s_flags & MS_RDONLY))
+				return 0;
 		}
 		if (!flexbg_flag)
 			first_block += EXT4_BLOCKS_PER_GROUP(sb);
@@ -2961,6 +2962,7 @@ static int ext4_remount (struct super_block * sb, int * flags, char * data)
 	ext4_fsblk_t n_blocks_count = 0;
 	unsigned long old_sb_flags;
 	struct ext4_mount_options old_opts;
+	ext4_group_t g;
 	int err;
 #ifdef CONFIG_QUOTA
 	int i;
@@ -3038,6 +3040,26 @@ static int ext4_remount (struct super_block * sb, int * flags, char * data)
 				goto restore_opts;
 			}
 
+			/*
+			 * Make sure the group descriptor checksums
+			 * are sane.  If they aren't, refuse to
+			 * remount r/w.
+			 */
+			for (g = 0; g < sbi->s_groups_count; g++) {
+				struct ext4_group_desc *gdp =
+					ext4_get_group_desc(sb, g, NULL);
+
+				if (!ext4_group_desc_csum_verify(sbi, g, gdp)) {
+					printk(KERN_ERR
+	       "EXT4-fs: ext4_remount: "
+		"Checksum for group %lu failed (%u!=%u)\n",
+		g, le16_to_cpu(ext4_group_desc_csum(sbi, g, gdp)),
+					       le16_to_cpu(gdp->bg_checksum));
+					err = -EINVAL;
+					goto restore_opts;
+				}
+			}
+
 			/*
 			 * If we have an unprocessed orphan list hanging
 			 * around from a previously readonly bdev mount,