New function reset_tree_block_csum() will do the black magic to reset csum for a tree block in-place.
This provides the basis to the whole tree csum resetting function. Signed-off-by: Qu Wenruo <[email protected]> --- cmds-check.c | 56 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 56 insertions(+) diff --git a/cmds-check.c b/cmds-check.c index 5817ecf..e4b4f4a 100644 --- a/cmds-check.c +++ b/cmds-check.c @@ -9137,6 +9137,62 @@ static u16 report_root_corrupted(struct btrfs_fs_info *fs_info, return ret; } +/* + * Black magics to reset the csum of a tree block. + * The evil part is to modify block without transaction/cow. + * + * Return 0 if the csum is OK or reset the csum + * Return <0 if error happened + */ +static int reset_tree_block_csum(struct btrfs_fs_info *fs_info, + u64 bytenr, u32 len) +{ + /* + * read_tree_block just use root as ladder to reach fs_info, + * so use chunk_root since it must be OK. + */ + struct btrfs_root *root = fs_info->chunk_root; + struct extent_buffer *eb; + char *buf = NULL; + u32 crc; + int ret = 0; + + eb = read_tree_block(root, bytenr, len, 0); + /* No need to do anything since its csum is OK */ + if (extent_buffer_uptodate(eb)) + goto out; + + buf = malloc(len); + if (!buf) { + ret = -ENOMEM; + goto out; + } + ret = read_data_from_disk(fs_info, buf, bytenr, len, 0); + if (ret < 0) + goto out; + crc = ~(u32)0; + crc = btrfs_csum_data(NULL, buf + BTRFS_CSUM_SIZE, crc, + len - BTRFS_CSUM_SIZE); + btrfs_csum_final(crc, buf); + ret = write_data_to_disk(fs_info, buf, bytenr, len, 0); + if (ret < 0) + goto out; + + /* Make sure now we can read the tree block */ + eb = read_tree_block(root, bytenr, len, 0); + if (!extent_buffer_uptodate(eb)) { + if (IS_ERR(eb)) + ret = PTR_ERR(eb); + else + ret = -EINVAL; + goto out; + } +out: + free(buf); + free_extent_buffer(eb); + return ret; +} + const char * const cmd_check_usage[] = { "btrfs check [options] <device>", "Check an unmounted btrfs filesystem.", -- 2.2.2 -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
