Commit 7503b83d authored Dec 19, 2018 by David Sterba

btrfs: move ulist allocation out of transaction in quota enable



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.

Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

parent aea6f028

fs/btrfs/qgroup.c

+6 −7

Original line number	Diff line number	Diff line
		@@ -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
		*/

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