On 2018/10/4 下午2:57, Nikolay Borisov wrote:
>
>
> 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 <wqu@xxxxxxxx>
>> ---
>> 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.
@generation is used for more than one location (chunk generation and
cache generation), while log root transid (along with chunk generation
and cache generation) isn't used more than twice.
Thus I only assign generation to @generation.
Thanks,
Qu
>
>> + 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;
>> }
>>
