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| author | Filipe Manana <fdmanana@suse.com> | 2025-07-01 15:44:16 +0100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2025-08-20 18:36:31 +0200 |
| commit | 452b9a1e8a2a8681d865afda9d75e944405e482b (patch) | |
| tree | 4e2aeef8ac29ae516a4d538c5783fce5f37a0eed | |
| parent | 2556c76192d9e094accfc8187f437bc065c52bef (diff) | |
| download | linux-452b9a1e8a2a8681d865afda9d75e944405e482b.tar.gz linux-452b9a1e8a2a8681d865afda9d75e944405e482b.zip | |
btrfs: qgroup: fix qgroup create ioctl returning success after quotas disabled
commit 08530d6e638427e7e1344bd67bacc03882ba95b9 upstream.
When quotas are disabled qgroup ioctls are supposed to return -ENOTCONN,
but the qgroup create ioctl stopped doing that when it races with a quota
disable operation, returning 0 instead. This change of behaviour happened
in commit 6ed05643ddb1 ("btrfs: create qgroup earlier in snapshot
creation").
The issue happens as follows:
1) Task A enters btrfs_ioctl_qgroup_create(), qgroups are enabled and so
qgroup_enabled() returns true since fs_info->quota_root is not NULL;
2) Task B enters btrfs_ioctl_quota_ctl() -> btrfs_quota_disable() and
disables qgroups, so now fs_info->quota_root is NULL;
3) Task A enters btrfs_create_qgroup() and calls btrfs_qgroup_mode(),
which returns BTRFS_QGROUP_MODE_DISABLED since quotas are disabled,
and then btrfs_create_qgroup() returns 0 to the caller, which makes
the ioctl return 0 instead of -ENOTCONN.
The check for fs_info->quota_root and returning -ENOTCONN if it's NULL
is made only after the call btrfs_qgroup_mode().
Fix this by moving the check for disabled quotas with btrfs_qgroup_mode()
into transaction.c:create_pending_snapshot(), so that we don't abort the
transaction if btrfs_create_qgroup() returns -ENOTCONN and quotas are
disabled.
Fixes: 6ed05643ddb1 ("btrfs: create qgroup earlier in snapshot creation")
CC: stable@vger.kernel.org # 6.12+
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | fs/btrfs/qgroup.c | 3 | ||||
| -rw-r--r-- | fs/btrfs/transaction.c | 6 |
2 files changed, 4 insertions, 5 deletions
diff --git a/fs/btrfs/qgroup.c b/fs/btrfs/qgroup.c index a062c21af5c4..1ccabbd59b12 100644 --- a/fs/btrfs/qgroup.c +++ b/fs/btrfs/qgroup.c @@ -1690,9 +1690,6 @@ int btrfs_create_qgroup(struct btrfs_trans_handle *trans, u64 qgroupid) struct btrfs_qgroup *prealloc = NULL; int ret = 0; - if (btrfs_qgroup_mode(fs_info) == BTRFS_QGROUP_MODE_DISABLED) - return 0; - mutex_lock(&fs_info->qgroup_ioctl_lock); if (!fs_info->quota_root) { ret = -ENOTCONN; diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c index f26a394a9ec5..2a14cc56956c 100644 --- a/fs/btrfs/transaction.c +++ b/fs/btrfs/transaction.c @@ -1736,8 +1736,10 @@ static noinline int create_pending_snapshot(struct btrfs_trans_handle *trans, ret = btrfs_create_qgroup(trans, objectid); if (ret && ret != -EEXIST) { - btrfs_abort_transaction(trans, ret); - goto fail; + if (ret != -ENOTCONN || btrfs_qgroup_enabled(fs_info)) { + btrfs_abort_transaction(trans, ret); + goto fail; + } } /* |