btrfs: fix one bug that process may endlessly wait for ticket in wait_reserve_ticket() (e0af2484) · Commits · 戴 / test

If can_overcommit() in btrfs_calc_reclaim_metadata_size() returns true, btrfs_async_reclaim_metadata_space() will not reclaim metadata space, just return directly and also forget to wake up process which are waiting for their tickets, so these processes will wait endlessly. Fstests case generic/172 with mount option "-o compress=lzo" have revealed this bug in my test machine. Here if we have tickets to handle, we must handle them first. Signed-off-by:

Wang Xiaoguang <wangxg.fnst@cn.fujitsu.com> Reviewed-by:

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

David Sterba <dsterba@suse.com>

fs/btrfs/extent-tree.c

+5 −5

Original line number	Diff line number	Diff line
		@@ -4901,11 +4901,6 @@ btrfs_calc_reclaim_metadata_size(struct btrfs_root *root,
		u64 expected;
		u64 to_reclaim = 0;

		to_reclaim = min_t(u64, num_online_cpus() * SZ_1M, SZ_16M);
		if (can_overcommit(root, space_info, to_reclaim,
		BTRFS_RESERVE_FLUSH_ALL))
		return 0;

		list_for_each_entry(ticket, &space_info->tickets, list)
		to_reclaim += ticket->bytes;
		list_for_each_entry(ticket, &space_info->priority_tickets, list)
		@@ -4913,6 +4908,11 @@ btrfs_calc_reclaim_metadata_size(struct btrfs_root *root,
		if (to_reclaim)
		return to_reclaim;

		to_reclaim = min_t(u64, num_online_cpus() * SZ_1M, SZ_16M);
		if (can_overcommit(root, space_info, to_reclaim,
		BTRFS_RESERVE_FLUSH_ALL))
		return 0;

		used = space_info->bytes_used + space_info->bytes_reserved +
		space_info->bytes_pinned + space_info->bytes_readonly +
		space_info->bytes_may_use;

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