The allocation happens with GFP_KERNEL after a transaction has been
started, this can potentially cause deadlock if reclaim tries to get the
memory by flushing filesystem data.
The fs_info::qgroup_ulist is not used during transaction start when
quotas are not enabled. The status bit BTRFS_FS_QUOTA_ENABLED is set
later in btrfs_quota_enable so it's safe to move it before the
transaction start.
Signed-off-by: David Sterba <dsterba@xxxxxxxx>
v2:
- use qgroup_ulist directly, drop the temporary variable
- update changelog
---
fs/btrfs/qgroup.c | 13 ++++++-------
1 file changed, 6 insertions(+), 7 deletions(-)
diff --git a/fs/btrfs/qgroup.c b/fs/btrfs/qgroup.c
index c1cd5558a646..eb680b715dd6 100644
--- a/fs/btrfs/qgroup.c
+++ b/fs/btrfs/qgroup.c
@@ -894,6 +894,12 @@ int btrfs_quota_enable(struct btrfs_fs_info *fs_info)
if (fs_info->quota_root)
goto out;
+ fs_info->qgroup_ulist = ulist_alloc(GFP_KERNEL);
+ if (!fs_info->qgroup_ulist) {
+ ret = -ENOMEM;
+ goto out;
+ }
+
/*
* 1 for quota root item
* 1 for BTRFS_QGROUP_STATUS item
@@ -909,13 +915,6 @@ int btrfs_quota_enable(struct btrfs_fs_info *fs_info)
goto out;
}
- fs_info->qgroup_ulist = ulist_alloc(GFP_KERNEL);
- if (!fs_info->qgroup_ulist) {
- ret = -ENOMEM;
- btrfs_abort_transaction(trans, ret);
- goto out;
- }
-
/*
* initially create the quota tree
*/
--
2.20.1
