On 20.03.2018 11:53, Anand Jain wrote:
> %csum_type is being checked to check the number of csum types we support,
> which is 1 as of now. Instead just check if the type matches with the
> only type we support, that is BTRFS_CSUM_TYPE_CRC32. And further adds
> cleanup.
>
> Signed-off-by: Anand Jain <anand.jain@xxxxxxxxxx>
> ---
> fs/btrfs/disk-io.c | 41 +++++++++++++++++++----------------------
> 1 file changed, 19 insertions(+), 22 deletions(-)
>
> diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
> index 1657d6aa4fa6..582ed6af3c50 100644
> --- a/fs/btrfs/disk-io.c
> +++ b/fs/btrfs/disk-io.c
> @@ -399,32 +399,29 @@ 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);
> - int ret = 0;
> -
> - if (csum_type == BTRFS_CSUM_TYPE_CRC32) {
> - u32 crc = ~(u32)0;
> - char result[sizeof(crc)];
> -
> - /*
> - * 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.
> - */
> - 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)))
> - ret = 1;
> - }
> + u32 crc = ~(u32)0;
> + char result[sizeof(crc)];
>
> - if (csum_type >= ARRAY_SIZE(btrfs_csum_sizes)) {
> + /* We support csum type crc32 only as of now */
> + if (csum_type != BTRFS_CSUM_TYPE_CRC32) {
> btrfs_err(fs_info, "unsupported checksum algorithm %u",
> - csum_type);
> - ret = 1;
> + csum_type);
> + return 1;
I think it would make sense to return EINVAL here. Then the sole caller
of this function (open_ctree) can use the code a bit more idiomatically:
ret = btrfs_check_super_csum()
if (ret < 0) {
handle failure
}
Right now we return 1 on both when the function fails due to invalid CRC
algorithm and if the checksum doesn't match. And we are going to print 2
things: unsupported checksum algorithm and the
btrfs_err(fs_info, "superblock checksum mismatch"); from open_ctree.
Let's implemented proper error returning strategy for this function.
> }
>
> - return ret;
> + /*
> + * 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.
> + */
> + 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)))
> + return 1;
Perhaps return EUCLEAN i.e something is corrupted hence the checksum
didn't pan out as we expected.
> +
> + return 0;
> }
>
> /*
>
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