On 4.10.2018 08:49, Qu Wenruo wrote:
> So we can detect log root related problem early and report the error
> more meaningfully other than hitting it log root read time.
>
> Signed-off-by: Qu Wenruo <w...@suse.com>
> ---
> fs/btrfs/disk-io.c | 28 ++++++++++++++++++++++------
> 1 file changed, 22 insertions(+), 6 deletions(-)
>
> diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
> index 5124c15705ce..34c68401c6bc 100644
> --- a/fs/btrfs/disk-io.c
> +++ b/fs/btrfs/disk-io.c
> @@ -2408,6 +2408,7 @@ static int validate_super(struct btrfs_fs_info *fs_info,
> {
> u64 nodesize = btrfs_super_nodesize(sb);
> u64 sectorsize = btrfs_super_sectorsize(sb);
> + u64 generation;
> int ret = 0;
>
> if (btrfs_super_magic(sb) != BTRFS_MAGIC) {
> @@ -2534,21 +2535,36 @@ static int validate_super(struct btrfs_fs_info
> *fs_info,
> ret = -EINVAL;
> }
>
> + generation = btrfs_super_generation(sb);
> /*
> * The generation is a global counter, we'll trust it more than the
> others
> * but it's still possible that it's the one that's wrong.
> */
> - if (btrfs_super_generation(sb) < btrfs_super_chunk_root_generation(sb))
> + if (generation < btrfs_super_chunk_root_generation(sb))
> btrfs_warn(fs_info,
> "suspicious: generation < chunk_root_generation: %llu <
> %llu",
> - btrfs_super_generation(sb),
> - btrfs_super_chunk_root_generation(sb));
> - if (btrfs_super_generation(sb) < btrfs_super_cache_generation(sb)
> + generation, btrfs_super_chunk_root_generation(sb));
> + if (generation < btrfs_super_cache_generation(sb)
> && btrfs_super_cache_generation(sb) != (u64)-1)
> btrfs_warn(fs_info,
> "suspicious: generation < cache_generation: %llu <
> %llu",
> - btrfs_super_generation(sb),
> - btrfs_super_cache_generation(sb));
> + generation, btrfs_super_cache_generation(sb));
> +
> + /*
> + * Check log root transid against super block generation.
> + *
> + * Older kernel doesn't populate log_root_transid, only need to check
> + * it when it's not zero.
> + * Since replaying suspicious log tree can cause serious problem, refuse
> + * to mount if it doesn't match.
> + */
> + if (btrfs_super_log_root_transid(sb) &&
> + btrfs_super_log_root_transid(sb) != generation + 1) {
nit: in the same vein as you do for btrfs_super_generation just assign
super_log_root_Transid to a local var and use that. IMO it's more
consistent with what's happening in this function.
> + btrfs_err(fs_info,
> + "bad log tree, log_root_transid != generation + 1: %llu != %llu + 1",
> + btrfs_super_log_root_transid(sb), generation);
> + ret = -EINVAL;
> + }
>
> return ret;
> }
>
