On 12.09.2018 01:06, Liu Bo wrote:
> As long as @eb is marked with EXTENT_BUFFER_DIRTY, all of its pages
> are dirty, so no need to set pages dirty again.
>
> Signed-off-by: Liu Bo <bo.liu@xxxxxxxxxxxxxxxxx>
Does make it any performance difference, numbers?
Reviewed-by: Nikolay Borisov <nborisov@xxxxxxxx>
> ---
> fs/btrfs/extent_io.c | 11 +++++++----
> fs/btrfs/extent_io.h | 2 +-
> 2 files changed, 8 insertions(+), 5 deletions(-)
>
> diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
> index 628f1aef34b0..fb2bf50134a1 100644
> --- a/fs/btrfs/extent_io.c
> +++ b/fs/btrfs/extent_io.c
> @@ -5165,11 +5165,11 @@ void clear_extent_buffer_dirty(struct extent_buffer *eb)
> WARN_ON(atomic_read(&eb->refs) == 0);
> }
>
> -int set_extent_buffer_dirty(struct extent_buffer *eb)
> +bool set_extent_buffer_dirty(struct extent_buffer *eb)
> {
> int i;
> int num_pages;
> - int was_dirty = 0;
> + bool was_dirty;
>
> check_buffer_tree_ref(eb);
>
> @@ -5179,8 +5179,11 @@ int set_extent_buffer_dirty(struct extent_buffer *eb)
> WARN_ON(atomic_read(&eb->refs) == 0);
> WARN_ON(!test_bit(EXTENT_BUFFER_TREE_REF, &eb->bflags));
>
> - for (i = 0; i < num_pages; i++)
> - set_page_dirty(eb->pages[i]);
> + if (!was_dirty) {
> + for (i = 0; i < num_pages; i++)
> + set_page_dirty(eb->pages[i]);
> + }
> +
> return was_dirty;
> }
>
> diff --git a/fs/btrfs/extent_io.h b/fs/btrfs/extent_io.h
> index b4d03e677e1d..f2ab42d57f02 100644
> --- a/fs/btrfs/extent_io.h
> +++ b/fs/btrfs/extent_io.h
> @@ -479,7 +479,7 @@ void extent_buffer_bitmap_set(struct extent_buffer *eb, unsigned long start,
> void extent_buffer_bitmap_clear(struct extent_buffer *eb, unsigned long start,
> unsigned long pos, unsigned long len);
> void clear_extent_buffer_dirty(struct extent_buffer *eb);
> -int set_extent_buffer_dirty(struct extent_buffer *eb);
> +bool set_extent_buffer_dirty(struct extent_buffer *eb);
> void set_extent_buffer_uptodate(struct extent_buffer *eb);
> void clear_extent_buffer_uptodate(struct extent_buffer *eb);
> int extent_buffer_under_io(struct extent_buffer *eb);
>
