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| author | Liu Bo <bo.li.liu@oracle.com> | 2014-07-02 12:58:01 +0400 |
|---|---|---|
| committer | Chris Mason <clm@fb.com> | 2014-07-03 18:04:15 +0400 |
| commit | d288db5dc0110c8e0732d099aaf7a05e2ea0e0c8 (patch) | |
| tree | 8f25c749e2d6199d47888278c3a22b5dc066249a /fs | |
| parent | 130d5b415a091e493ac1508b9d27bbb85ba7b8c0 (diff) | |
| download | linux-d288db5dc0110c8e0732d099aaf7a05e2ea0e0c8.tar.xz | |
Btrfs: fix race of using total_bytes_pinned
This percpu counter @total_bytes_pinned is introduced to skip unnecessary
operations of 'commit transaction', it accounts for those space we may free
but are stuck in delayed refs.
And we zero out @space_info->total_bytes_pinned every transaction period so
we have a better idea of how much space we'll actually free up by committing
this transaction. However, we do the 'zero out' part a little earlier, before
we actually unpin space, so we end up returning ENOSPC when we actually have
free space that's just unpinned from committing transaction.
xfstests/generic/074 complained then.
This fixes it by actually accounting the percpu pinned number when 'unpin',
and since it's protected by space_info->lock, the race is gone now.
Signed-off-by: Liu Bo <bo.li.liu@oracle.com>
Reviewed-by: Miao Xie <miaox@cn.fujitsu.com>
Signed-off-by: Chris Mason <clm@fb.com>
Diffstat (limited to 'fs')
| -rw-r--r-- | fs/btrfs/extent-tree.c | 5 |
1 files changed, 1 insertions, 4 deletions
diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c index 99c253918208..813537f362f9 100644 --- a/fs/btrfs/extent-tree.c +++ b/fs/btrfs/extent-tree.c @@ -5678,7 +5678,6 @@ void btrfs_prepare_extent_commit(struct btrfs_trans_handle *trans, struct btrfs_caching_control *next; struct btrfs_caching_control *caching_ctl; struct btrfs_block_group_cache *cache; - struct btrfs_space_info *space_info; down_write(&fs_info->commit_root_sem); @@ -5701,9 +5700,6 @@ void btrfs_prepare_extent_commit(struct btrfs_trans_handle *trans, up_write(&fs_info->commit_root_sem); - list_for_each_entry_rcu(space_info, &fs_info->space_info, list) - percpu_counter_set(&space_info->total_bytes_pinned, 0); - update_global_block_rsv(fs_info); } @@ -5741,6 +5737,7 @@ static int unpin_extent_range(struct btrfs_root *root, u64 start, u64 end) spin_lock(&cache->lock); cache->pinned -= len; space_info->bytes_pinned -= len; + percpu_counter_add(&space_info->total_bytes_pinned, -len); if (cache->ro) { space_info->bytes_readonly += len; readonly = true; |