Gentle ping.

Although this is just a dirty fix, it would be much better to avoid seed
device users yelling at me.

Thanks,
Qu

On 2019/1/8 下午2:08, Qu Wenruo wrote:
> [BUG]
> Linux v5.0-rc1 will fail fstests/btrfs/163 with the following kernel
> message:
> 
>   BTRFS error (device dm-6): dev extent devid 1 physical offset 13631488 len 
> 8388608 is beyond device boundary 0
>   BTRFS error (device dm-6): failed to verify dev extents against chunks: -117
>   BTRFS error (device dm-6): open_ctree failed
> 
> [CAUSE]
> Commit cf90d884b347 ("btrfs: Introduce mount time chunk <-> dev extent
> mapping check") introduced strict check on dev extents.
> 
> We use btrfs_find_device() with dev uuid and fs uuid set to NULL, and
> only dependent on @devid to find the real device.
> 
> For seed devices, we call clone_fs_devices() in open_seed_devices() to
> allow us search seed devices directly.
> 
> However clone_fs_devices() just populates devices with devid and dev
> uuid, without populating other essential members, like disk_total_bytes.
> 
> This makes any device returned by btrfs_find_device(fs_info, devid,
> NULL, NULL) is just a dummy, with 0 disk_total_bytes, and any dev
> extents on the seed device will not pass the device boundary check.
> 
> [FIX]
> This patch will try to verify the device returned by btrfs_find_device()
> and if it's a dummy then re-search in seed devices.
> 
> Reported-by: Filipe Manana <[email protected]>
> Fixes: cf90d884b347 ("btrfs: Introduce mount time chunk <-> dev extent 
> mapping check")
> Signed-off-by: Qu Wenruo <[email protected]>
> ---
>  fs/btrfs/volumes.c | 12 ++++++++++++
>  1 file changed, 12 insertions(+)
> 
> diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
> index 2576b1a379c9..3e4f8f88353e 100644
> --- a/fs/btrfs/volumes.c
> +++ b/fs/btrfs/volumes.c
> @@ -7825,6 +7825,18 @@ static int verify_one_dev_extent(struct btrfs_fs_info 
> *fs_info,
>               ret = -EUCLEAN;
>               goto out;
>       }
> +
> +     /* It's possible this device is a dummy for seed device */
> +     if (dev->disk_total_bytes == 0) {
> +             dev = find_device(fs_info->fs_devices->seed, devid, NULL);
> +             if (!dev) {
> +                     btrfs_err(fs_info, "failed to find seed devid %llu",
> +                               devid);
> +                     ret = -EUCLEAN;
> +                     goto out;
> +             }
> +     }
> +
>       if (physical_offset + physical_len > dev->disk_total_bytes) {
>               btrfs_err(fs_info,
>  "dev extent devid %llu physical offset %llu len %llu is beyond device 
> boundary %llu",
> 

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