Gentle ping
2017-10-24 1:29 GMT+03:00 Timofey Titovets <nefelim4ag@xxxxxxxxx>:
> We need to call extent_range_clear_dirty_for_io()
> on compression range to prevent application from changing
> page content, while pages compressing.
>
> extent_range_clear_dirty_for_io() run on each loop iteration,
> "(end - start)" can be much (up to 1024 times) bigger
> then compression range (BTRFS_MAX_UNCOMPRESSED).
>
> That produce extra calls to page managment code.
>
> Fix that behaviour by call extent_range_clear_dirty_for_io()
> only once.
>
> v1 -> v2:
> - Make that more obviously and more safeprone
>
> v2 -> v3:
> - Rebased on:
> Btrfs: compress_file_range() remove dead variable num_bytes
> - Update change log
> - Add comments
>
> v3 -> v4:
> - Rebased on: kdave for-next
> - To avoid dirty bit clear/set behaviour change
> call clear_bit once, istead of per compression range
>
> Signed-off-by: Timofey Titovets <nefelim4ag@xxxxxxxxx>
> ---
> fs/btrfs/inode.c | 6 ++++--
> 1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
> index b93fe05a39c7..5816dd3cb6e6 100644
> --- a/fs/btrfs/inode.c
> +++ b/fs/btrfs/inode.c
> @@ -536,8 +536,10 @@ static noinline void compress_file_range(struct inode *inode,
> * If the compression fails for any reason, we set the pages
> * dirty again later on.
> */
> - extent_range_clear_dirty_for_io(inode, start, end);
> - redirty = 1;
> + if (!redirty) {
> + extent_range_clear_dirty_for_io(inode, start, end);
> + redirty = 1;
> + }
>
> /* Compression level is applied here and only here */
> ret = btrfs_compress_pages(
> --
> 2.14.2
--
Have a nice day,
Timofey.
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