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btrfs: fix one bug that process may endlessly wait for ticket in wait_reserve_ticket()

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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>
This commit is contained in:
Wang Xiaoguang 2016-08-31 19:46:16 +08:00 committed by David Sterba
parent a9b1fc851d
commit e0af24849e
1 changed files with 5 additions and 5 deletions
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10
fs/btrfs/extent-tree.c
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@ -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;