During the scan context, we aren't verifying the superblock- checksum when read. This patch fixes it by adding the checksum verification function btrfs_check_super_csum() in the function btrfs_read_disk_super(). And makes device scan to error fail if the primary superblock csum is wrong, whereas if the copy-superblock csum is wrong it will just just report mismatch and continue mount/scan as usual. When the mount is successful We anyway overwrite all superblocks upon unmount.
The context in which this will be called is - device scan, device ready, and mount -o device option. Test script: Corrupt primary superblock and check if device scan and mount fails: mkfs.btrfs -fq /dev/sdc dd if=/dev/urandom of=/dev/sdc ibs=1 obs=1 count=1 seek=64K btrfs dev scan /dev/sdc mount /dev/sdc /btrfs Corrupt secondary superblock and check if device scan and mount is succcessful, check for the dmesg for errors. mkfs.btrfs -fq /dev/sdc dd if=/dev/urandom of=/dev/sdc ibs=1 obs=1 count=1 seek=67108864 btrfs dev scan /dev/sdc mount /dev/sdc /btrfs Signed-off-by: Anand Jain <anand.j...@oracle.com> Reviewed-by: Nikolay Borisov <nbori...@suse.com> --- v3->v4: Update changelog v2->v3: squash 4/8 in here. 4/8: btrfs: make btrfs_check_super_csum() non-static v1->v2: changed title. use explicit (< 0) check for %errr. Un-split pr_err() string. Fix typo in the git commit log. Move the csum check after bytenr and btrfs magic verified. fs/btrfs/disk-io.c | 2 +- fs/btrfs/disk-io.h | 1 + fs/btrfs/volumes.c | 13 +++++++++++++ 3 files changed, 15 insertions(+), 1 deletion(-) diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c index c3a9407fc3a5..37b0cf489fdd 100644 --- a/fs/btrfs/disk-io.c +++ b/fs/btrfs/disk-io.c @@ -395,7 +395,7 @@ static int verify_parent_transid(struct extent_io_tree *io_tree, * Otherwise: -EINVAL if csum type is not found * -EUCLEAN if csum does not match */ -static int btrfs_check_super_csum(char *raw_disk_sb) +int btrfs_check_super_csum(char *raw_disk_sb) { struct btrfs_super_block *disk_sb = (struct btrfs_super_block *)raw_disk_sb; diff --git a/fs/btrfs/disk-io.h b/fs/btrfs/disk-io.h index 70a88d61b547..c400cc68f913 100644 --- a/fs/btrfs/disk-io.h +++ b/fs/btrfs/disk-io.h @@ -69,6 +69,7 @@ int write_all_supers(struct btrfs_fs_info *fs_info, int max_mirrors); 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_check_super_csum(char *raw_disk_sb); int btrfs_commit_super(struct btrfs_fs_info *fs_info); struct btrfs_root *btrfs_read_fs_root(struct btrfs_root *tree_root, struct btrfs_key *location); diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c index 035affa447fa..760c6650e11b 100644 --- a/fs/btrfs/volumes.c +++ b/fs/btrfs/volumes.c @@ -1149,6 +1149,7 @@ static int btrfs_read_disk_super(struct block_device *bdev, u64 bytenr, struct page **page, struct btrfs_super_block **disk_super) { + int err; void *p; pgoff_t index; @@ -1183,6 +1184,18 @@ static int btrfs_read_disk_super(struct block_device *bdev, u64 bytenr, return -EINVAL; } + err = btrfs_check_super_csum((char *) *disk_super); + if (err < 0) { + if (err == -EINVAL) + pr_err("BTRFS error (device %pg): unsupported checksum type, bytenr=%llu", + bdev, bytenr); + else if (err == -EUCLEAN) + pr_err("BTRFS error (device %pg): superblock checksum failed, bytenr=%llu", + bdev, bytenr); + btrfs_release_disk_super(*page); + return err; + } + if ((*disk_super)->label[0] && (*disk_super)->label[BTRFS_LABEL_SIZE - 1]) (*disk_super)->label[BTRFS_LABEL_SIZE - 1] = '\0'; -- 2.7.0 -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html