Btrfs: fix deadlock with freeze and sync V2 (bd7de2c9) · Commits · 戴 / test

We can deadlock with freeze right now because we unconditionally start a transaction in our ->sync_fs() call. To fix this just check and see if we have a running transaction to commit. This saves us from the deadlock because at this point we'll have the umount sem for the sb so we're safe from freezes coming in after we've done our check. With this patch the freeze xfstests no longer deadlocks. Thanks, Signed-off-by:

Josef Bacik <jbacik@fusionio.com> Signed-off-by:

Chris Mason <chris.mason@oracle.com>

fs/btrfs/super.c

+9 −4

Original line number	Diff line number	Diff line
		@@ -813,7 +813,6 @@ int btrfs_sync_fs(struct super_block *sb, int wait)
		struct btrfs_trans_handle *trans;
		struct btrfs_fs_info *fs_info = btrfs_sb(sb);
		struct btrfs_root *root = fs_info->tree_root;
		int ret;

		trace_btrfs_sync_fs(wait);

		@@ -824,11 +823,17 @@ int btrfs_sync_fs(struct super_block *sb, int wait)

		btrfs_wait_ordered_extents(root, 0, 0);

		trans = btrfs_start_transaction(root, 0);
		spin_lock(&fs_info->trans_lock);
		if (!fs_info->running_transaction) {
		spin_unlock(&fs_info->trans_lock);
		return 0;
		}
		spin_unlock(&fs_info->trans_lock);

		trans = btrfs_join_transaction(root);
		if (IS_ERR(trans))
		return PTR_ERR(trans);
		ret = btrfs_commit_transaction(trans, root);
		return ret;
		return btrfs_commit_transaction(trans, root);
		}

		static int btrfs_show_options(struct seq_file seq, struct dentry dentry)

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