Re: [PATCH 02/13] btrfs: Do per-chunk check for mount time check

[Hugo Mills <hugo@carfax.org.uk>]

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   What happened to these patches? (Particularly the per-chunk
degraded checks). We've just had someone on IRC who could have used
the capability...

   Hugo.

On Tue, May 10, 2016 at 10:09:21PM +0800, Anand Jain wrote:
> From: Qu Wenruo <quwenruo@cn.fujitsu.com>
> 
> Now use the btrfs_check_degraded() to do mount time degraded check.
> 
> With this patch, now we can mount with the following case:
>  # mkfs.btrfs -f -m raid1 -d single /dev/sdb /dev/sdc
>  # wipefs -a /dev/sdc
>  # mount /dev/sdb /mnt/btrfs -o degraded
>  As the single data chunk is only in sdb, so it's OK to mount as degraded,
>  as missing one device is OK for RAID1.
> 
> But still fail with the following case as expected:
>  # mkfs.btrfs -f -m raid1 -d single /dev/sdb /dev/sdc
>  # wipefs -a /dev/sdb
>  # mount /dev/sdc /mnt/btrfs -o degraded
>  As the data chunk is only in sdb, so it's not OK to mount it as degraded.
> 
> Reported-by: Zhao Lei <zhaolei@cn.fujitsu.com>
> Reported-by: Anand Jain <anand.jain@oracle.com>
> Signed-off-by: Qu Wenruo <quwenruo@cn.fujitsu.com>
> 
> [Btrfs: use btrfs_error instead of btrfs_err during mount]
> Signed-off-by: Anand Jain <anand.jain@oracle.com>
> ---
>  fs/btrfs/disk-io.c | 18 ++++++++++--------
>  1 file changed, 10 insertions(+), 8 deletions(-)
> 
> diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
> index d01f89d130e0..4f91a049fbca 100644
> --- a/fs/btrfs/disk-io.c
> +++ b/fs/btrfs/disk-io.c
> @@ -2885,6 +2885,16 @@ int open_ctree(struct super_block *sb,
>  		goto fail_tree_roots;
>  	}
>  
> +	ret = btrfs_check_degradable(fs_info, fs_info->sb->s_flags);
> +	if (ret < 0) {
> +		btrfs_err(fs_info, "degraded writable mount failed %d", ret);
> +		goto fail_tree_roots;
> +	} else if (ret > 0 && !btrfs_test_opt(chunk_root, DEGRADED)) {
> +		btrfs_warn(fs_info,
> +			"Some device missing, but still degraded mountable, please mount with -o degraded option");
> +		ret = -EACCES;
> +		goto fail_tree_roots;
> +	}
>  	/*
>  	 * keep the device that is marked to be the target device for the
>  	 * dev_replace procedure
> @@ -2988,14 +2998,6 @@ retry_root_backup:
>  	}
>  	fs_info->num_tolerated_disk_barrier_failures =
>  		btrfs_calc_num_tolerated_disk_barrier_failures(fs_info);
> -	if (fs_info->fs_devices->missing_devices >
> -	     fs_info->num_tolerated_disk_barrier_failures &&
> -	    !(sb->s_flags & MS_RDONLY)) {
> -		pr_warn("BTRFS: missing devices(%llu) exceeds the limit(%d), writeable mount is not allowed\n",
> -			fs_info->fs_devices->missing_devices,
> -			fs_info->num_tolerated_disk_barrier_failures);
> -		goto fail_sysfs;
> -	}
>  
>  	fs_info->cleaner_kthread = kthread_run(cleaner_kthread, tree_root,
>  					       "btrfs-cleaner");
> -- 
> 2.7.0
> 
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-- 
Hugo Mills             | Anyone who says their system is completely secure
hugo@... carfax.org.uk | understands neither systems nor security.
http://carfax.org.uk/  |
PGP: E2AB1DE4          |                                        Bruce Schneier

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