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Commit 8a266467 authored by Theodore Ts'o's avatar Theodore Ts'o
Browse files

ext4: Allow read/only mounts with corrupted block group checksums 



If the block group checksums are corrupted, still allow the mount to
succeed, so e2fsck can have a chance to try to fix things up.  Add
code in the remount r/w path to make sure the block group checksums
are valid before allowing the filesystem to be remounted read/write.

Signed-off-by: default avatar"Theodore Ts'o" <tytso@mit.edu>
parent d03856bd

fs/ext4/super.c

+23 −1
Original line number Diff line number Diff line
@@ -1626,6 +1626,7 @@ 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));

			if (!(sb->s_flags & MS_RDONLY))

				return 0;

		}

		if (!flexbg_flag)
@@ -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,