On 2.07.2018 10:44, Ethan Lien wrote:
> 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().
>
> Signed-off-by: Ethan Lien <ethanl...@synology.com>
Reviewed-by: Nikolay Borisov <nbori...@suse.com>
Also this needs the following tag:
Fixes: e2d845211eda ("Btrfs: use percpu counter for dirty metadata count")
And perhaps stable from 4.4 onwards. But David will take care
of that. So the patch is good.
> ---
> fs/btrfs/disk-io.c | 10 ++++++----
> 1 file changed, 6 insertions(+), 4 deletions(-)
>
> diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
> index 205092dc9390..dfed08e70ec1 100644
> --- a/fs/btrfs/disk-io.c
> +++ b/fs/btrfs/disk-io.c
> @@ -961,8 +961,9 @@ static int btree_writepages(struct address_space *mapping,
>
> 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;
> }
> @@ -4150,8 +4151,9 @@ static void __btrfs_btree_balance_dirty(struct
> btrfs_fs_info *fs_info,
> if (flush_delayed)
> btrfs_balance_delayed_items(fs_info);
>
> - 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) {
>
> balance_dirty_pages_ratelimited(fs_info->btree_inode->i_mapping);
> }
>
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