Re: [PATCH] btrfs: tree-checker: Don't check max block group size as current max chunk size limit is unreliable

[Qu Wenruo <quwenruo.btrfs@gmx.com>]

[-- Attachment #1.1: Type: text/plain, Size: 2519 bytes --]

Gentle ping.

Please put this patch into current release as the new block group size
limit check introduced in v4.19 is causing at least 2 reports in mail list.

Thanks,
Qu

On 2018/11/23 上午9:06, Qu Wenruo wrote:
> [BUG]
> A completely valid btrfs will refuse to mount, with error message like:
>   BTRFS critical (device sdb2): corrupt leaf: root=2 block=239681536 slot=172 \
>     bg_start=12018974720 bg_len=10888413184, invalid block group size, \
>     have 10888413184 expect (0, 10737418240]
> 
> Btrfs check returns no error, and all kernels used on this fs is later
> than 2011, which should all have the 10G size limit commit.
> 
> [CAUSE]
> For a 12 devices btrfs, we could allocate a chunk larger than 10G due to
> stripe stripe bump up.
> 
> __btrfs_alloc_chunk()
> |- max_stripe_size = 1G
> |- max_chunk_size = 10G
> |- data_stripe = 11
> |- if (1G * 11 > 10G) {
>        stripe_size = 976128930;
>        stripe_size = round_up(976128930, SZ_16M) = 989855744
> 
> However the final stripe_size (989855744) * 11 = 10888413184, which is
> still larger than 10G.
> 
> [FIX]
> For the comprehensive check, we need to do the full check at chunk
> read time, and rely on bg <-> chunk mapping to do the check.
> 
> We could just skip the length check for now.
> 
> Fixes: fce466eab7ac ("btrfs: tree-checker: Verify block_group_item")
> Cc: stable@vger.kernel.org # v4.19+
> Reported-by: Wang Yugui <wangyugui@e16-tech.com>
> Signed-off-by: Qu Wenruo <wqu@suse.com>
> ---
>  fs/btrfs/tree-checker.c | 8 +++-----
>  1 file changed, 3 insertions(+), 5 deletions(-)
> 
> diff --git a/fs/btrfs/tree-checker.c b/fs/btrfs/tree-checker.c
> index cab0b1f1f741..d8bd5340fbbc 100644
> --- a/fs/btrfs/tree-checker.c
> +++ b/fs/btrfs/tree-checker.c
> @@ -389,13 +389,11 @@ static int check_block_group_item(struct btrfs_fs_info *fs_info,
>  
>  	/*
>  	 * Here we don't really care about alignment since extent allocator can
> -	 * handle it.  We care more about the size, as if one block group is
> -	 * larger than maximum size, it's must be some obvious corruption.
> +	 * handle it.  We care more about the size.
>  	 */
> -	if (key->offset > BTRFS_MAX_DATA_CHUNK_SIZE || key->offset == 0) {
> +	if (key->offset == 0) {
>  		block_group_err(fs_info, leaf, slot,
> -			"invalid block group size, have %llu expect (0, %llu]",
> -				key->offset, BTRFS_MAX_DATA_CHUNK_SIZE);
> +				"invalid block group size 0");
>  		return -EUCLEAN;
>  	}
>  
> 


[-- Attachment #2: OpenPGP digital signature --]
[-- Type: application/pgp-signature, Size: 488 bytes --]