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Commit bdfb6ff4 authored by Darrick J. Wong's avatar Darrick J. Wong Committed by Theodore Ts'o
Browse files

ext4: mark group corrupt on group descriptor checksum 



If the group descriptor fails validation, mark the whole blockgroup
corrupt so that the inode/block allocators skip this group.  The
previous approach takes the risk of writing to a damaged group
descriptor; hopefully it was never the case that the [ib]bitmap fields
pointed to another valid block and got dirtied, since the memset would
fill the page with 1s.

Signed-off-by: default avatarDarrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: default avatar"Theodore Ts'o" <tytso@mit.edu>
parent 87a39389

fs/ext4/balloc.c

+4 −5
Original line number Diff line number Diff line
@@ -184,6 +184,7 @@ void ext4_init_block_bitmap(struct super_block *sb, struct buffer_head *bh, 
	struct ext4_sb_info *sbi = EXT4_SB(sb);

	ext4_fsblk_t start, tmp;

	int flex_bg = 0;

	struct ext4_group_info *grp;



	J_ASSERT_BH(bh, buffer_locked(bh));
@@ -191,11 +192,9 @@ void ext4_init_block_bitmap(struct super_block *sb, struct buffer_head *bh, 
	 * essentially implementing a per-group read-only flag. */

	if (!ext4_group_desc_csum_verify(sb, block_group, gdp)) {

		ext4_error(sb, "Checksum bad for group %u", block_group);

		ext4_free_group_clusters_set(sb, gdp, 0);

		ext4_free_inodes_set(sb, gdp, 0);

		ext4_itable_unused_set(sb, gdp, 0);

		memset(bh->b_data, 0xff, sb->s_blocksize);

		ext4_block_bitmap_csum_set(sb, block_group, gdp, bh);

		grp = ext4_get_group_info(sb, block_group);

		set_bit(EXT4_GROUP_INFO_BBITMAP_CORRUPT_BIT, &grp->bb_state);

		set_bit(EXT4_GROUP_INFO_IBITMAP_CORRUPT_BIT, &grp->bb_state);

		return;

	}

	memset(bh->b_data, 0, sb->s_blocksize);

fs/ext4/ialloc.c

+4 −6
Original line number Diff line number Diff line
@@ -70,18 +70,16 @@ static unsigned ext4_init_inode_bitmap(struct super_block *sb, 
				       ext4_group_t block_group,

				       struct ext4_group_desc *gdp)

{

	struct ext4_group_info *grp;

	J_ASSERT_BH(bh, buffer_locked(bh));



	/* If checksum is bad mark all blocks and inodes use to prevent

	 * allocation, essentially implementing a per-group read-only flag. */

	if (!ext4_group_desc_csum_verify(sb, block_group, gdp)) {

		ext4_error(sb, "Checksum bad for group %u", block_group);

		ext4_free_group_clusters_set(sb, gdp, 0);

		ext4_free_inodes_set(sb, gdp, 0);

		ext4_itable_unused_set(sb, gdp, 0);

		memset(bh->b_data, 0xff, sb->s_blocksize);

		ext4_inode_bitmap_csum_set(sb, block_group, gdp, bh,

					   EXT4_INODES_PER_GROUP(sb) / 8);

		grp = ext4_get_group_info(sb, block_group);

		set_bit(EXT4_GROUP_INFO_BBITMAP_CORRUPT_BIT, &grp->bb_state);

		set_bit(EXT4_GROUP_INFO_IBITMAP_CORRUPT_BIT, &grp->bb_state);

		return 0;

	}