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From: David Sterba <dsterba@suse.cz>
To: Qu Wenruo <wqu@suse.com>
Cc: linux-btrfs@vger.kernel.org
Subject: Re: [PATCH v3 10/26] btrfs: introduce submit_compressed_bio() for compression
Date: Mon, 4 Oct 2021 21:42:31 +0200	[thread overview]
Message-ID: <20211004194231.GC9286@twin.jikos.cz> (raw)
In-Reply-To: <20210927072208.21634-11-wqu@suse.com>

On Mon, Sep 27, 2021 at 03:21:52PM +0800, Qu Wenruo wrote:
> The new helper, submit_compressed_bio(), will aggregate the following
> work:
> 
> - Increase compressed_bio::pending_bios
> - Remap the endio function
> - Map and submit the bio
> 
> Signed-off-by: Qu Wenruo <wqu@suse.com>
> ---
>  fs/btrfs/compression.c | 45 ++++++++++++++++++------------------------
>  1 file changed, 19 insertions(+), 26 deletions(-)
> 
> diff --git a/fs/btrfs/compression.c b/fs/btrfs/compression.c
> index b6ed5933caf5..3f0be97d17f3 100644
> --- a/fs/btrfs/compression.c
> +++ b/fs/btrfs/compression.c
> @@ -422,6 +422,21 @@ static void end_compressed_bio_write(struct bio *bio)
>  	bio_put(bio);
>  }
>  
> +static blk_status_t submit_compressed_bio(struct btrfs_fs_info *fs_info,
> +					  struct compressed_bio *cb,
> +					  struct bio *bio, int mirror_num)
> +{
> +	blk_status_t ret;
> +
> +	ASSERT(bio->bi_iter.bi_size);
> +	atomic_inc(&cb->pending_bios);
> +	ret = btrfs_bio_wq_end_io(fs_info, bio, BTRFS_WQ_ENDIO_DATA);
> +	if (ret)
> +		return ret;
> +	ret = btrfs_map_bio(fs_info, bio, mirror_num);
> +	return ret;
> +}
> +
>  /*
>   * worker function to build and submit bios for previously compressed pages.
>   * The corresponding pages in the inode should be marked for writeback
> @@ -518,19 +533,13 @@ blk_status_t btrfs_submit_compressed_write(struct btrfs_inode *inode, u64 start,
>  
>  		page->mapping = NULL;
>  		if (submit || len < PAGE_SIZE) {
> -			atomic_inc(&cb->pending_bios);
> -			ret = btrfs_bio_wq_end_io(fs_info, bio,
> -						  BTRFS_WQ_ENDIO_DATA);
> -			if (ret)
> -				goto finish_cb;
> -
>  			if (!skip_sum) {
>  				ret = btrfs_csum_one_bio(inode, bio, start, 1);
>  				if (ret)
>  					goto finish_cb;
>  			}
>  
> -			ret = btrfs_map_bio(fs_info, bio, 0);
> +			ret = submit_compressed_bio(fs_info, cb, bio, 0);

Can you please send me an explanation why it's still OK to aggregate the
calls as it changes the order. Originally there's

	atomic_inc
	btrfs_bio_wq_end_io
	btrfs_csum_one_bio
	btrfs_map_bio

While in the new code:

	btrfs_csum_one_bio
	from submit_compressed_bio:
		atomic_inc
		btrfs_bio_wq_end_io
		btrfs_map_bio

So in particular the order of

atomic_inc+btrfs_bio_wq_end_io is in reverse order with
btrfs_csum_one_bio

> @@ -889,7 +887,7 @@ blk_status_t btrfs_submit_compressed_read(struct inode *inode, struct bio *bio,
>  						  fs_info->sectorsize);
>  			sums += fs_info->csum_size * nr_sectors;
>  
> -			ret = btrfs_map_bio(fs_info, comp_bio, mirror_num);
> +			ret = submit_compressed_bio(fs_info, cb, comp_bio, mirror_num);
>  			if (ret)
>  				goto finish_cb;
>  
> @@ -904,16 +902,11 @@ blk_status_t btrfs_submit_compressed_read(struct inode *inode, struct bio *bio,
>  		cur_disk_byte += pg_len;
>  	}
>  
> -	atomic_inc(&cb->pending_bios);
> -	ret = btrfs_bio_wq_end_io(fs_info, comp_bio, BTRFS_WQ_ENDIO_DATA);
> -	if (ret)
> -		goto last_bio;
> -
>  	ret = btrfs_lookup_bio_sums(inode, comp_bio, sums);
>  	if (ret)
>  		goto last_bio;
>  
> -	ret = btrfs_map_bio(fs_info, comp_bio, mirror_num);
> +	ret = submit_compressed_bio(fs_info, cb, comp_bio, mirror_num);

Same for btrfs_lookup_bio_sums instead of btrfs_csum_one_bio.

  reply	other threads:[~2021-10-04 19:42 UTC|newest]

Thread overview: 37+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-27  7:21 [PATCH v3 00/26] Qu Wenruo
2021-09-27  7:21 ` [PATCH v3 01/26] btrfs: remove unused parameter @nr_pages in add_ra_bio_pages() Qu Wenruo
2021-09-27  7:21 ` [PATCH v3 02/26] btrfs: remove unnecessary parameter @delalloc_start for writepage_delalloc() Qu Wenruo
2021-09-27  7:21 ` [PATCH v3 03/26] btrfs: use async_chunk::async_cow to replace the confusing pending pointer Qu Wenruo
2021-09-27  7:21 ` [PATCH v3 04/26] btrfs: don't pass compressed pages to btrfs_writepage_endio_finish_ordered() Qu Wenruo
2021-09-27  7:21 ` [PATCH v3 05/26] btrfs: make add_ra_bio_pages() to be subpage compatible Qu Wenruo
2021-10-04 17:45   ` David Sterba
2021-10-04 22:39     ` Qu Wenruo
2021-09-27  7:21 ` [PATCH v3 06/26] btrfs: introduce compressed_bio::pending_sectors to trace compressed bio more elegantly Qu Wenruo
2021-09-27  7:21 ` [PATCH v3 07/26] btrfs: add subpage checked bitmap to make PageChecked flag to be subpage compatible Qu Wenruo
2021-09-27  7:21 ` [PATCH v3 08/26] btrfs: handle errors properly inside btrfs_submit_compressed_read() Qu Wenruo
2021-09-27  7:21 ` [PATCH v3 09/26] btrfs: handle errors properly inside btrfs_submit_compressed_write() Qu Wenruo
2021-09-27  7:21 ` [PATCH v3 10/26] btrfs: introduce submit_compressed_bio() for compression Qu Wenruo
2021-10-04 19:42   ` David Sterba [this message]
2021-10-04 22:41     ` Qu Wenruo
2021-09-27  7:21 ` [PATCH v3 11/26] btrfs: introduce alloc_compressed_bio() " Qu Wenruo
2021-09-27  7:21 ` [PATCH v3 12/26] btrfs: make btrfs_submit_compressed_read() to determine stripe boundary at bio allocation time Qu Wenruo
2021-10-04 20:10   ` David Sterba
2021-10-05  6:24     ` Qu Wenruo
2021-09-27  7:21 ` [PATCH v3 13/26] btrfs: make btrfs_submit_compressed_write() " Qu Wenruo
2021-09-27  7:21 ` [PATCH v3 14/26] btrfs: remove unused function btrfs_bio_fits_in_stripe() Qu Wenruo
2021-09-27  7:21 ` [PATCH v3 15/26] btrfs: refactor submit_compressed_extents() Qu Wenruo
2021-10-05 16:33   ` David Sterba
2021-09-27  7:21 ` [PATCH v3 16/26] btrfs: cleanup for extent_write_locked_range() Qu Wenruo
2021-09-27  7:21 ` [PATCH v3 17/26] btrfs: make compress_file_range() to be subpage compatible Qu Wenruo
2021-09-27  7:22 ` [PATCH v3 18/26] btrfs: make btrfs_submit_compressed_write() " Qu Wenruo
2021-09-27  7:22 ` [PATCH v3 19/26] btrfs: make end_compressed_bio_writeback() to be subpage compatble Qu Wenruo
2021-09-27  7:22 ` [PATCH v3 20/26] btrfs: make extent_write_locked_range() to be subpage compatible Qu Wenruo
2021-10-13 14:50   ` Josef Bacik
2021-10-14  0:08     ` Qu Wenruo
2021-09-27  7:22 ` [PATCH v3 21/26] btrfs: extract uncompressed async extent submission code into a new helper Qu Wenruo
2021-09-27  7:22 ` [PATCH v3 22/26] btrfs: rework lzo_compress_pages() to make it subpage compatible Qu Wenruo
2021-09-27  7:22 ` [PATCH v3 23/26] btrfs: teach __extent_writepage() to handle locked page differently Qu Wenruo
2021-09-27  7:22 ` [PATCH v3 24/26] btrfs: allow page to be unlocked by btrfs_page_end_writer_lock() even if it's locked by plain page_lock() Qu Wenruo
2021-09-27  7:22 ` [PATCH v3 25/26] btrfs: don't run delalloc range which is beyond the locked_page to prevent deadlock for subpage compression Qu Wenruo
2021-09-27  7:22 ` [PATCH v3 26/26] btrfs: only allow subpage compression if the range is fully page aligned Qu Wenruo
2021-10-05 17:21 ` [PATCH v3 00/26] David Sterba

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