On Tue, Feb 13, 2018 at 05:50:43PM +0800, Anand Jain wrote:
> As -o subvolid mount option is an u64 manage it as %u for
> token verifications, instead of %s.
> 
> Signed-off-by: Anand Jain <anand.j...@oracle.com>
> ---
>  fs/btrfs/super.c | 23 ++++++++++-------------
>  1 file changed, 10 insertions(+), 13 deletions(-)
> 
> diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
> index 8112619cac95..bf629c8a6a47 100644
> --- a/fs/btrfs/super.c
> +++ b/fs/btrfs/super.c
> @@ -336,7 +336,7 @@ enum {
>  static const match_table_t tokens = {
>       {Opt_degraded, "degraded"},
>       {Opt_subvol, "subvol=%s"},
> -     {Opt_subvolid, "subvolid=%s"},
> +     {Opt_subvolid, "subvolid=%u"},

This gets implemented as simple_strtoul, deep in the perser it uses an
unsigned long long and then casts to usigned long. Long and long-long
are same only on subset of architectures, so we'd need to either extend
teh parser capabilities to really do u64 or we'd have to use the %s and
match_u64.

Though a subvolid larger than full 32bit number is unlikely, for sake of
correctness I think we should stick to the constraints of the subvolid
that allows u64.

>       {Opt_device, "device=%s"},
>       {Opt_nodatasum, "nodatasum"},
>       {Opt_datasum, "datasum"},
> @@ -964,8 +964,8 @@ static int btrfs_parse_subvol_options(const char 
> *options, fmode_t flags,
>  {
>       substring_t args[MAX_OPT_ARGS];
>       char *opts, *orig, *p;
> -     char *num = NULL;
>       int error = 0;
> +     u64 subvolid;
>  
>       if (!options)
>               return 0;
> @@ -995,18 +995,15 @@ static int btrfs_parse_subvol_options(const char 
> *options, fmode_t flags,
>                       }
>                       break;
>               case Opt_subvolid:
> -                     num = match_strdup(&args[0]);
> -                     if (num) {
> -                             *subvol_objectid = memparse(num, NULL);
> -                             kfree(num);
> -                             /* we want the original fs_tree */
> -                             if (!*subvol_objectid)
> -                                     *subvol_objectid =
> -                                             BTRFS_FS_TREE_OBJECTID;
> -                     } else {
> -                             error = -EINVAL;
> +                     error = match_u64(&args[0], &subvolid);

So this is the right way (with the %s), as memparse accepts the size
suffixes (K/M/G/...), that we don't want for a subvolume id.

> +                     if (error)
>                               goto out;
> -                     }
> +
> +                     /* we want the original fs_tree */
> +                     if (subvolid == 0)
> +                             subvolid = BTRFS_FS_TREE_OBJECTID;
> +
> +                     *subvol_objectid = subvolid;
>                       break;
>               case Opt_subvolrootid:
>                       pr_warn("BTRFS: 'subvolrootid' mount option is 
> deprecated and has no effect\n");
> -- 
> 2.7.0
> 
> --
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