[PATCH 3.16 109/328] btrfs: use correct compare function of dirty_metadata_bytes

Ben Hutchings
2018-12-09T22:06:28Z

From: Ethan Lien <ethanlien@synology.com>

commit d814a49198eafa6163698bdd93961302f3a877a4 upstream.

We use customized, nodesize batch value to update dirty_metadata_bytes.
We should also use batch version of compare function or we will easily
goto fast path and get false result from percpu_counter_compare().

Fixes: e2d845211eda ("Btrfs: use percpu counter for dirty metadata count")
Signed-off-by: Ethan Lien <ethanlien@synology.com>
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
[bwh: Backported to 3.16: In __btrfs_btree_balance_dirty(), use
root->fs_info instead of fs_info]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
fs/btrfs/disk-io.c | 10 ++++++----
1 file changed, 6 insertions(+), 4 deletions(-)

--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -991,8 +991,9 @@ static int btree_writepages(struct addre

fs_info = BTRFS_I(mapping->host)->root->fs_info;
/* this is a bit racy, but that's ok */
- ret = percpu_counter_compare(&fs_info->dirty_metadata_bytes,
- BTRFS_DIRTY_METADATA_THRESH);
+ ret = __percpu_counter_compare(&fs_info->dirty_metadata_bytes,
+ BTRFS_DIRTY_METADATA_THRESH,
+ fs_info->dirty_metadata_batch);
if (ret < 0)
return 0;
}
@@ -3793,8 +3794,9 @@ static void __btrfs_btree_balance_dirty(
if (flush_delayed)
btrfs_balance_delayed_items(root);

- ret = percpu_counter_compare(&root->fs_info->dirty_metadata_bytes,
- BTRFS_DIRTY_METADATA_THRESH);
+ ret = __percpu_counter_compare(&root->fs_info->dirty_metadata_bytes,
+ BTRFS_DIRTY_METADATA_THRESH,
+ root->fs_info->dirty_metadata_batch);
if (ret > 0) {
balance_dirty_pages_ratelimited(
root->fs_info->btree_inode->i_mapping);