On 13.03.2018 17:06, Anand Jain wrote:
> We aren't checking the SB csum when the device scanned,
> instead we do that when mounting the device, and if the
> csum fails we fail the mount. How if we check the csum
> when the device is scanned, I can't see any reason for
> why not? any idea?
So what problems does this solve? Only net "gain" I see is making a
function public (which is a minus in my book) thus expanding the public
interface.
>
> Signed-off-by: Anand Jain <anand.jain@xxxxxxxxxx>
> ---
> fs/btrfs/disk-io.c | 9 +++++----
> fs/btrfs/disk-io.h | 2 ++
> fs/btrfs/volumes.c | 4 ++++
> 3 files changed, 11 insertions(+), 4 deletions(-)
>
> diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
> index 156116655a32..28e71e2aaa92 100644
> --- a/fs/btrfs/disk-io.c
> +++ b/fs/btrfs/disk-io.c
> @@ -393,8 +393,8 @@ static int verify_parent_transid(struct extent_io_tree *io_tree,
> * Return 0 if the superblock checksum type matches the checksum value of that
> * algorithm. Pass the raw disk superblock data.
> */
> -static int btrfs_check_super_csum(struct btrfs_fs_info *fs_info,
> - char *raw_disk_sb)
> +int btrfs_check_super_csum(struct btrfs_fs_info *fs_info,
> + char *raw_disk_sb)
> {
> struct btrfs_super_block *disk_sb =
> (struct btrfs_super_block *)raw_disk_sb;
> @@ -420,8 +420,9 @@ static int btrfs_check_super_csum(struct btrfs_fs_info *fs_info,
> }
>
> if (csum_type >= ARRAY_SIZE(btrfs_csum_sizes)) {
> - btrfs_err(fs_info, "unsupported checksum algorithm %u",
> - csum_type);
> + if (fs_info)
> + btrfs_err(fs_info, "unsupported checksum algorithm %u",
> + csum_type);
> ret = 1;
> }
>
> diff --git a/fs/btrfs/disk-io.h b/fs/btrfs/disk-io.h
> index 70a88d61b547..683e4b0c4e24 100644
> --- a/fs/btrfs/disk-io.h
> +++ b/fs/btrfs/disk-io.h
> @@ -70,6 +70,8 @@ struct buffer_head *btrfs_read_dev_super(struct block_device *bdev);
> int btrfs_read_dev_one_super(struct block_device *bdev, int copy_num,
> struct buffer_head **bh_ret);
> int btrfs_commit_super(struct btrfs_fs_info *fs_info);
> +int btrfs_check_super_csum(struct btrfs_fs_info *fs_info,
> + char *raw_disk_sb);
> struct btrfs_root *btrfs_read_fs_root(struct btrfs_root *tree_root,
> struct btrfs_key *location);
> int btrfs_init_fs_root(struct btrfs_root *root);
> diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
> index 1e72357bdfa8..af34b8a611a0 100644
> --- a/fs/btrfs/volumes.c
> +++ b/fs/btrfs/volumes.c
> @@ -677,6 +677,10 @@ static int btrfs_open_one_device(struct btrfs_fs_devices *fs_devices,
> if (ret)
> return ret;
>
> + if (btrfs_check_super_csum(NULL, bh->b_data)) {
> + pr_err("BTRFS: superblock checksum mismatch");
> + goto error_brelse;
> + }
> disk_super = (struct btrfs_super_block *)bh->b_data;
> devid = btrfs_stack_device_id(&disk_super->dev_item);
> if (devid != device->devid)
>
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