Re: [PATCH v2 1/2] btrfs: add support for SUPER_FLAG_CHANGING_FSID in btrfs.ko

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

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On 2018年01月08日 13:04, Anand Jain wrote:
> Userland sets SUPER_FLAG_CHANGING_FSID and resets it only when changing
> fsid is complete. Its not a good idea to mount the device anything in
> between, so this patch fails the mount if SB SUPER_FLAG_CHANGING_FSID
> is set.
> 
> Signed-off-by: Anand Jain <anand.jain@oracle.com>
>   cc: wqu@suse.com
> ---
> v1->v2: Oops. Fix cut and paste error, remove ~. My bad.
> 
>  fs/btrfs/disk-io.c              | 7 ++++++-
>  include/uapi/linux/btrfs_tree.h | 1 +
>  2 files changed, 7 insertions(+), 1 deletion(-)
> 
> diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
> index a69e5944dc08..0dd215258ff9 100644
> --- a/fs/btrfs/disk-io.c
> +++ b/fs/btrfs/disk-io.c
> @@ -61,7 +61,8 @@
>  				 BTRFS_HEADER_FLAG_RELOC |\
>  				 BTRFS_SUPER_FLAG_ERROR |\
>  				 BTRFS_SUPER_FLAG_SEEDING |\
> -				 BTRFS_SUPER_FLAG_METADUMP)
> +				 BTRFS_SUPER_FLAG_METADUMP |\
> +				 BTRFS_SUPER_FLAG_CHANGING_FSID)

Still the same problem here.

Since that super flag is excluded in btrfs_check_super_valid(), I didn't
see any meaning including it into BTRFS_SUPER_FLAG_SUPP, and it will
confuse later BTRFS_SUPER_FLAG_SUPP users.

Thanks,
Qu

>  
>  static const struct extent_io_ops btree_extent_io_ops;
>  static void end_workqueue_fn(struct btrfs_work *work);
> @@ -3906,6 +3907,10 @@ static int btrfs_check_super_valid(struct btrfs_fs_info *fs_info)
>  		btrfs_err(fs_info, "no valid FS found");
>  		ret = -EINVAL;
>  	}
> +	if (btrfs_super_flags(sb) & BTRFS_SUPER_FLAG_CHANGING_FSID) {
> +		btrfs_err(fs_info, "SUPER_FLAG_CHANGING_FSID is set");
> +		ret = -EINVAL;
> +	}
>  	if (btrfs_super_flags(sb) & ~BTRFS_SUPER_FLAG_SUPP)
>  		btrfs_warn(fs_info, "unrecognized super flag: %llu",
>  				btrfs_super_flags(sb) & ~BTRFS_SUPER_FLAG_SUPP);
> diff --git a/include/uapi/linux/btrfs_tree.h b/include/uapi/linux/btrfs_tree.h
> index 38ab0e06259a..aff1356c2bb8 100644
> --- a/include/uapi/linux/btrfs_tree.h
> +++ b/include/uapi/linux/btrfs_tree.h
> @@ -457,6 +457,7 @@ struct btrfs_free_space_header {
>  #define BTRFS_SUPER_FLAG_SEEDING	(1ULL << 32)
>  #define BTRFS_SUPER_FLAG_METADUMP	(1ULL << 33)
>  #define BTRFS_SUPER_FLAG_METADUMP_V2	(1ULL << 34)
> +#define BTRFS_SUPER_FLAG_CHANGING_FSID	(1ULL << 35)
>  
>  
>  /*
> 


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