[PATCH] btrfs-progs: parse-utils: allow single number qgroup id

[Qu Wenruo <wqu@suse.com>]

[BUG]
Since btrfs-progs v5.14, fstests/btrfs/099 always fail with the
following output in 099.full:

  ...
  # /usr/bin/btrfs quota enable /mnt/scratch
  # /usr/bin/btrfs qgroup limit 134217728 5 /mnt/scratch
  ERROR: invalid qgroupid or subvolume path: 5
  failed: '/usr/bin/btrfs qgroup limit 134217728 5 /mnt/scratch'

[CAUSE]
Since commit cb5a542871f9 ("btrfs-progs: factor out plain qgroupid
parsing"), btrfs qgroup parser no longer accepts single number qgroup id
like "5" used in that test case.

That commit is not a plain refactor without functional change, but
removed a simple feature.

[FIX]
Add back the handling for single number qgroupid.

Fixes: cb5a542871f9 ("btrfs-progs: factor out plain qgroupid parsing")
Signed-off-by: Qu Wenruo <wqu@suse.com>
---
 common/parse-utils.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/common/parse-utils.c b/common/parse-utils.c
index ad57b74a7b64..863ca9f25fd8 100644
--- a/common/parse-utils.c
+++ b/common/parse-utils.c
@@ -290,6 +290,12 @@ int parse_qgroupid(const char *str, u64 *qgroupid)
 	level = strtoull(str, &end, 10);
 	if (str == end)
 		return -EINVAL;
+	/* We accept single qgroupid like "5", to indicate "0/5"*/
+	if (end[0] == '\0') {
+		*qgroupid = level;
+		return 0;
+	}
+	/* Otherwise qgroupid must go like "1/256" */
 	if (end[0] != '/')
 		return -EINVAL;
 	str = end + 1;
-- 
2.33.0