Re: [PATCH 15/40] btrfs: don't allocate a btrfs_bio for scrub bios

[Qu Wenruo <quwenruo.btrfs@xxxxxxx>]

On 2022/3/22 23:55, Christoph Hellwig wrote:
> All the scrub bios go straight to the block device or the raid56 code,
> none of which looks at the btrfs_bio.

Exactly!

Reviewed-by: Qu Wenruo <wqu@xxxxxxxx>

Thanks,
Qu
> Signed-off-by: Christoph Hellwig <hch@xxxxxx>
> ---
>   fs/btrfs/scrub.c | 47 ++++++++++++++++++-----------------------------
>   1 file changed, 18 insertions(+), 29 deletions(-)
>
> diff --git a/fs/btrfs/scrub.c b/fs/btrfs/scrub.c
> index bb9382c02714f..250d271b02341 100644
> --- a/fs/btrfs/scrub.c
> +++ b/fs/btrfs/scrub.c
> @@ -1415,8 +1415,8 @@ static void scrub_recheck_block_on_raid56(struct btrfs_fs_info *fs_info,
>   	if (!first_page->dev->bdev)
>   		goto out;
>
> -	bio = btrfs_bio_alloc(BIO_MAX_VECS);
> -	bio_set_dev(bio, first_page->dev->bdev);
> +	bio = bio_alloc(first_page->dev->bdev, BIO_MAX_VECS, REQ_OP_READ,
> +			GFP_NOFS);
>
>   	for (page_num = 0; page_num < sblock->page_count; page_num++) {
>   		struct scrub_page *spage = sblock->pagev[page_num];
> @@ -1649,8 +1649,6 @@ static int scrub_add_page_to_wr_bio(struct scrub_ctx *sctx,
>   	}
>   	sbio = sctx->wr_curr_bio;
>   	if (sbio->page_count == 0) {
> -		struct bio *bio;
> -
>   		ret = fill_writer_pointer_gap(sctx,
>   					      spage->physical_for_dev_replace);
>   		if (ret) {
> @@ -1661,17 +1659,14 @@ static int scrub_add_page_to_wr_bio(struct scrub_ctx *sctx,
>   		sbio->physical = spage->physical_for_dev_replace;
>   		sbio->logical = spage->logical;
>   		sbio->dev = sctx->wr_tgtdev;
> -		bio = sbio->bio;
> -		if (!bio) {
> -			bio = btrfs_bio_alloc(sctx->pages_per_bio);
> -			sbio->bio = bio;
> +		if (!sbio->bio) {
> +			sbio->bio = bio_alloc(sbio->dev->bdev,
> +					      sctx->pages_per_bio,
> +					      REQ_OP_WRITE, GFP_NOFS);
>   		}
> -
> -		bio->bi_private = sbio;
> -		bio->bi_end_io = scrub_wr_bio_end_io;
> -		bio_set_dev(bio, sbio->dev->bdev);
> -		bio->bi_iter.bi_sector = sbio->physical >> 9;
> -		bio->bi_opf = REQ_OP_WRITE;
> +		sbio->bio->bi_private = sbio;
> +		sbio->bio->bi_end_io = scrub_wr_bio_end_io;
> +		sbio->bio->bi_iter.bi_sector = sbio->physical >> 9;
>   		sbio->status = 0;
>   	} else if (sbio->physical + sbio->page_count * sectorsize !=
>   		   spage->physical_for_dev_replace ||
> @@ -1712,7 +1707,6 @@ static void scrub_wr_submit(struct scrub_ctx *sctx)
>
>   	sbio = sctx->wr_curr_bio;
>   	sctx->wr_curr_bio = NULL;
> -	WARN_ON(!sbio->bio->bi_bdev);
>   	scrub_pending_bio_inc(sctx);
>   	/* process all writes in a single worker thread. Then the block layer
>   	 * orders the requests before sending them to the driver which
> @@ -2084,22 +2078,17 @@ static int scrub_add_page_to_rd_bio(struct scrub_ctx *sctx,
>   	}
>   	sbio = sctx->bios[sctx->curr];
>   	if (sbio->page_count == 0) {
> -		struct bio *bio;
> -
>   		sbio->physical = spage->physical;
>   		sbio->logical = spage->logical;
>   		sbio->dev = spage->dev;
> -		bio = sbio->bio;
> -		if (!bio) {
> -			bio = btrfs_bio_alloc(sctx->pages_per_bio);
> -			sbio->bio = bio;
> +		if (!sbio->bio) {
> +			sbio->bio = bio_alloc(sbio->dev->bdev,
> +					      sctx->pages_per_bio,
> +					      REQ_OP_READ, GFP_NOFS);
>   		}
> -
> -		bio->bi_private = sbio;
> -		bio->bi_end_io = scrub_bio_end_io;
> -		bio_set_dev(bio, sbio->dev->bdev);
> -		bio->bi_iter.bi_sector = sbio->physical >> 9;
> -		bio->bi_opf = REQ_OP_READ;
> +		sbio->bio->bi_private = sbio;
> +		sbio->bio->bi_end_io = scrub_bio_end_io;
> +		sbio->bio->bi_iter.bi_sector = sbio->physical >> 9;
>   		sbio->status = 0;
>   	} else if (sbio->physical + sbio->page_count * sectorsize !=
>   		   spage->physical ||
> @@ -2215,7 +2204,7 @@ static void scrub_missing_raid56_pages(struct scrub_block *sblock)
>   		goto bioc_out;
>   	}
>
> -	bio = btrfs_bio_alloc(BIO_MAX_VECS);
> +	bio = bio_alloc(NULL, BIO_MAX_VECS, REQ_OP_READ, GFP_NOFS);
>   	bio->bi_iter.bi_sector = logical >> 9;
>   	bio->bi_private = sblock;
>   	bio->bi_end_io = scrub_missing_raid56_end_io;
> @@ -2831,7 +2820,7 @@ static void scrub_parity_check_and_repair(struct scrub_parity *sparity)
>   	if (ret || !bioc || !bioc->raid_map)
>   		goto bioc_out;
>
> -	bio = btrfs_bio_alloc(BIO_MAX_VECS);
> +	bio = bio_alloc(NULL, BIO_MAX_VECS, REQ_OP_READ, GFP_NOFS);
>   	bio->bi_iter.bi_sector = sparity->logic_start >> 9;
>   	bio->bi_private = sparity;
>   	bio->bi_end_io = scrub_parity_bio_endio;