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 qgroup_ulist is not used during transaction start as the quotas are not yet enabled but to provide the same semantics, use a temporary variable and assign fs_info::qgroup_ulist as before. Signed-off-by: David Sterba <[email protected]> --- fs/btrfs/qgroup.c | 14 ++++++++------ 1 file changed, 8 insertions(+), 6 deletions(-) diff --git a/fs/btrfs/qgroup.c b/fs/btrfs/qgroup.c index c1cd5558a646..9e49d5e132b8 100644 --- a/fs/btrfs/qgroup.c +++ b/fs/btrfs/qgroup.c @@ -887,6 +887,7 @@ int btrfs_quota_enable(struct btrfs_fs_info *fs_info) struct btrfs_key found_key; struct btrfs_qgroup *qgroup = NULL; struct btrfs_trans_handle *trans = NULL; + struct ulist *tmp_ulist; int ret = 0; int slot; @@ -894,6 +895,12 @@ int btrfs_quota_enable(struct btrfs_fs_info *fs_info) if (fs_info->quota_root) goto out; + tmp_ulist = ulist_alloc(GFP_KERNEL); + if (!tmp_ulist) { + ret = -ENOMEM; + goto out; + } + /* * 1 for quota root item * 1 for BTRFS_QGROUP_STATUS item @@ -909,12 +916,7 @@ 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; - } + fs_info->qgroup_ulist = tmp_ulist; /* * initially create the quota tree -- 2.20.1
