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Commit 51bce6c9 authored by Johannes Thumshirn's avatar Johannes Thumshirn Committed by David Sterba
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btrfs: Simplify btrfs_check_super_csum() and get rid of size assumptions 



Now that we have already checked for a valid checksum type before
calling btrfs_check_super_csum(), it can be simplified even further.

While at it get rid of the implicit size assumption of the resulting
checksum as well.

This is a preparation for changing all checksum functionality to use the
crypto layer later.

Reviewed-by: default avatarNikolay Borisov <nborisov@suse.com>
Signed-off-by: default avatarJohannes Thumshirn <jthumshirn@suse.de>
Reviewed-by: default avatarDavid Sterba <dsterba@suse.com>
Signed-off-by: default avatarDavid Sterba <dsterba@suse.com>
parent 8dc3f22c

fs/btrfs/disk-io.c

+16 −26
Original line number Diff line number Diff line
@@ -371,30 +371,20 @@ static int btrfs_check_super_csum(struct btrfs_fs_info *fs_info, 
{

	struct btrfs_super_block *disk_sb =

		(struct btrfs_super_block *)raw_disk_sb;

	u16 csum_type = btrfs_super_csum_type(disk_sb);



	if (!btrfs_supported_super_csum(csum_type)) {

		btrfs_err(fs_info, "unsupported checksum algorithm %u",

			  csum_type);

		return 1;

	}



	if (csum_type == BTRFS_CSUM_TYPE_CRC32) {

	u32 crc = ~(u32)0;

		char result[sizeof(crc)];

	char result[BTRFS_CSUM_SIZE];



	/*

	 * The super_block structure does not span the whole

		 * BTRFS_SUPER_INFO_SIZE range, we expect that the unused space

		 * is filled with zeros and is included in the checksum.

	 * BTRFS_SUPER_INFO_SIZE range, we expect that the unused space is

	 * filled with zeros and is included in the checksum.

	 */

	crc = btrfs_csum_data(raw_disk_sb + BTRFS_CSUM_SIZE,

			      crc, BTRFS_SUPER_INFO_SIZE - BTRFS_CSUM_SIZE);

	btrfs_csum_final(crc, result);



		if (memcmp(raw_disk_sb, result, sizeof(result)))

	if (memcmp(disk_sb->csum, result, btrfs_super_csum_size(disk_sb)))

		return 1;

	}



	return 0;

}
@@ -2611,6 +2601,7 @@ int open_ctree(struct super_block *sb, 
	u32 stripesize;

	u64 generation;

	u64 features;

	u16 csum_type;

	struct btrfs_key location;

	struct buffer_head *bh;

	struct btrfs_super_block *disk_super;
@@ -2820,11 +2811,10 @@ int open_ctree(struct super_block *sb, 
	 * Verify the type first, if that or the the checksum value are

	 * corrupted, we'll find out

	 */

	if (!btrfs_supported_super_csum(btrfs_super_csum_type(

				 (struct btrfs_super_block *) bh->b_data))) {

	csum_type = btrfs_super_csum_type((struct btrfs_super_block *)bh->b_data);

	if (!btrfs_supported_super_csum(csum_type)) {

		btrfs_err(fs_info, "unsupported checksum algorithm: %u",

			  btrfs_super_csum_type((struct btrfs_super_block *)

						bh->b_data));

			  csum_type);

		err = -EINVAL;

		brelse(bh);

		goto fail_alloc;