[PATCH] btrfs: check/qgroup: fix two error messages used in qgroup verification

[PATCH] btrfs: check/qgroup: fix two error messages used in qgroup verification

[Qu Wenruo]

[BUG]
There is a weird error message when running btrfs check on a specific
immage:

 [7/7] checking quota groups
 ERROR: out of memory
 ERROR: Loading qgroups from disk: -2
 ERROR: failed to check quota groups

[CAUSE]
The "Out of memory" one is in load_quota_info(), which is output in two
cases:

- No memory can be allocated for btrfs_qgroup_list
  AKA, real -ENOMEM.

- No qgroup can be found for either the child or the parent qgroup
  This returnes -ENOENT.

Obvious the image has hit -ENOENT case, but the error message is fixed
to ENOMEM case.

[FIX]
Fix it by using %m to output the real reason of failure.

Reported-by: Andrei Borzenkov <arvidjaar@gmail.com>
Link: https://forums.opensuse.org/showthread.php/567851-btrfs-fails-to-load-qgroups-from-disk-with-error-2-(out-of-memory)
Signed-off-by: Qu Wenruo <wqu@suse.com>
---
 check/qgroup-verify.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/check/qgroup-verify.c b/check/qgroup-verify.c
index 0813b8412057..d1478a40fde3 100644
--- a/check/qgroup-verify.c
+++ b/check/qgroup-verify.c
@@ -977,7 +977,11 @@ loop:
 					ret = add_qgroup_relation(key.objectid,
 								  key.offset);
 					if (ret) {
-						error("out of memory");
+						errno = -ret;
+						error(
+		"failed to add qgroup relation, member=%llu parent=%llu: %m",
+						      key.objectid,
+						      key.offset);
 						goto out;
 					}
 				}
-- 
2.35.1

Re: [PATCH] btrfs: check/qgroup: fix two error messages used in qgroup verification

[David Sterba]

On Thu, Mar 17, 2022 at 02:12:50PM +0800, Qu Wenruo wrote:
> [BUG]
> There is a weird error message when running btrfs check on a specific
> immage:
> 
>  [7/7] checking quota groups
>  ERROR: out of memory
>  ERROR: Loading qgroups from disk: -2
>  ERROR: failed to check quota groups
> 
> [CAUSE]
> The "Out of memory" one is in load_quota_info(), which is output in two
> cases:
> 
> - No memory can be allocated for btrfs_qgroup_list
>   AKA, real -ENOMEM.
> 
> - No qgroup can be found for either the child or the parent qgroup
>   This returnes -ENOENT.
> 
> Obvious the image has hit -ENOENT case, but the error message is fixed
> to ENOMEM case.
> 
> [FIX]
> Fix it by using %m to output the real reason of failure.
> 
> Reported-by: Andrei Borzenkov <arvidjaar@gmail.com>
> Link: https://forums.opensuse.org/showthread.php/567851-btrfs-fails-to-load-qgroups-from-disk-with-error-2-(out-of-memory)
> Signed-off-by: Qu Wenruo <wqu@suse.com>

Added to devel, thanks.