After an ordered extent completes, don't blindly reset the
inode's ordered tree last accessed ordered extent pointer.
While running the xfstests I noticed that about 29% of the
time the ordered extent to which tree->last pointed was not
the same as our just completed ordered extent. After that I
ran the following sysbench test (after a prepare phase) and
noticed that about 68% of the time tree->last pointed to
a different ordered extent too.
sysbench --test=fileio --file-num=32 --file-total-size=4G \
--file-test-mode=rndwr --num-threads=512 \
--file-block-size=32768 --max-time=60 --max-requests=0 run
Therefore reset tree->last on ordered extent removal only if
it pointed to the ordered extent we're removing from the tree.
Signed-off-by: Filipe David Borba Manana <fdmanana@xxxxxxxxx>
---
fs/btrfs/ordered-data.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/fs/btrfs/ordered-data.c b/fs/btrfs/ordered-data.c
index 69582d5..b8c2ded 100644
--- a/fs/btrfs/ordered-data.c
+++ b/fs/btrfs/ordered-data.c
@@ -520,7 +520,8 @@ void btrfs_remove_ordered_extent(struct inode *inode,
spin_lock_irq(&tree->lock);
node = &entry->rb_node;
rb_erase(node, &tree->tree);
- tree->last = NULL;
+ if (tree->last == node)
+ tree->last = NULL;
set_bit(BTRFS_ORDERED_COMPLETE, &entry->flags);
spin_unlock_irq(&tree->lock);
--
1.7.9.5
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