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Date: Wed, 20 May 2015 11:10:53 -0700
From: Ming Lin <mlin@...nel.org>
To: Christoph Hellwig <hch@....de>
Cc: Ming Lin <mlin@...nel.org>, lkml <linux-kernel@...r.kernel.org>,
Jens Axboe <axboe@...nel.dk>,
Kent Overstreet <kent.overstreet@...il.com>,
Dongsu Park <dpark@...teo.net>
Subject: Re: [PATCH v3 00/11] simplify block layer based on immutable biovecs
On Wed, May 20, 2015 at 5:48 AM, Christoph Hellwig <hch@....de> wrote:
> Passes test fine for me so far. You might also want to throw in the
> following patch to make it more useful:
I'll add it to next version.
Thanks.
>
> ---
> From a30035d4ae040723a6c94143db90231941d0caf7 Mon Sep 17 00:00:00 2001
> From: Kent Overstreet <kmo@...erainc.com>
> Date: Tue, 19 May 2015 14:31:01 +0200
> Subject: block: remove bio_get_nr_vecs()
>
> We can always fill up the bio now, no need to estimate the possible
> size based on queue parameters.
>
> Signed-off-by: Kent Overstreet <kmo@...erainc.com>
> [hch: rebased and wrote a changelog]
> Signed-off-by: Christoph Hellwig <hch@....de>
> ---
> block/bio.c | 23 -----------------------
> drivers/md/dm-io.c | 2 +-
> fs/btrfs/compression.c | 5 +----
> fs/btrfs/extent_io.c | 9 ++-------
> fs/btrfs/inode.c | 3 +--
> fs/btrfs/scrub.c | 18 ++----------------
> fs/direct-io.c | 2 +-
> fs/ext4/page-io.c | 3 +--
> fs/ext4/readpage.c | 2 +-
> fs/gfs2/lops.c | 9 +--------
> fs/logfs/dev_bdev.c | 4 ++--
> fs/mpage.c | 4 ++--
> fs/nilfs2/segbuf.c | 2 +-
> fs/xfs/xfs_aops.c | 3 +--
> include/linux/bio.h | 1 -
> 15 files changed, 17 insertions(+), 73 deletions(-)
>
> diff --git a/block/bio.c b/block/bio.c
> index ae31cdb..f59b647 100644
> --- a/block/bio.c
> +++ b/block/bio.c
> @@ -677,29 +677,6 @@ integrity_clone:
> EXPORT_SYMBOL(bio_clone_bioset);
>
> /**
> - * bio_get_nr_vecs - return approx number of vecs
> - * @bdev: I/O target
> - *
> - * Return the approximate number of pages we can send to this target.
> - * There's no guarantee that you will be able to fit this number of pages
> - * into a bio, it does not account for dynamic restrictions that vary
> - * on offset.
> - */
> -int bio_get_nr_vecs(struct block_device *bdev)
> -{
> - struct request_queue *q = bdev_get_queue(bdev);
> - int nr_pages;
> -
> - nr_pages = min_t(unsigned,
> - queue_max_segments(q),
> - queue_max_sectors(q) / (PAGE_SIZE >> 9) + 1);
> -
> - return min_t(unsigned, nr_pages, BIO_MAX_PAGES);
> -
> -}
> -EXPORT_SYMBOL(bio_get_nr_vecs);
> -
> -/**
> * bio_add_pc_page - attempt to add page to bio
> * @q: the target queue
> * @bio: destination bio
> diff --git a/drivers/md/dm-io.c b/drivers/md/dm-io.c
> index 74adcd2..7d64272 100644
> --- a/drivers/md/dm-io.c
> +++ b/drivers/md/dm-io.c
> @@ -314,7 +314,7 @@ static void do_region(int rw, unsigned region, struct dm_io_region *where,
> if ((rw & REQ_DISCARD) || (rw & REQ_WRITE_SAME))
> num_bvecs = 1;
> else
> - num_bvecs = min_t(int, bio_get_nr_vecs(where->bdev),
> + num_bvecs = min_t(int, BIO_MAX_PAGES,
> dm_sector_div_up(remaining, (PAGE_SIZE >> SECTOR_SHIFT)));
>
> bio = bio_alloc_bioset(GFP_NOIO, num_bvecs, io->client->bios);
> diff --git a/fs/btrfs/compression.c b/fs/btrfs/compression.c
> index ce62324..449c752 100644
> --- a/fs/btrfs/compression.c
> +++ b/fs/btrfs/compression.c
> @@ -97,10 +97,7 @@ static inline int compressed_bio_size(struct btrfs_root *root,
> static struct bio *compressed_bio_alloc(struct block_device *bdev,
> u64 first_byte, gfp_t gfp_flags)
> {
> - int nr_vecs;
> -
> - nr_vecs = bio_get_nr_vecs(bdev);
> - return btrfs_bio_alloc(bdev, first_byte >> 9, nr_vecs, gfp_flags);
> + return btrfs_bio_alloc(bdev, first_byte >> 9, BIO_MAX_PAGES, gfp_flags);
> }
>
> static int check_compressed_csum(struct inode *inode,
> diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
> index 43af5a6..a37af69 100644
> --- a/fs/btrfs/extent_io.c
> +++ b/fs/btrfs/extent_io.c
> @@ -2799,9 +2799,7 @@ static int submit_extent_page(int rw, struct extent_io_tree *tree,
> {
> int ret = 0;
> struct bio *bio;
> - int nr;
> int contig = 0;
> - int this_compressed = bio_flags & EXTENT_BIO_COMPRESSED;
> int old_compressed = prev_bio_flags & EXTENT_BIO_COMPRESSED;
> size_t page_size = min_t(size_t, size, PAGE_CACHE_SIZE);
>
> @@ -2826,12 +2824,9 @@ static int submit_extent_page(int rw, struct extent_io_tree *tree,
> return 0;
> }
> }
> - if (this_compressed)
> - nr = BIO_MAX_PAGES;
> - else
> - nr = bio_get_nr_vecs(bdev);
>
> - bio = btrfs_bio_alloc(bdev, sector, nr, GFP_NOFS | __GFP_HIGH);
> + bio = btrfs_bio_alloc(bdev, sector, BIO_MAX_PAGES,
> + GFP_NOFS | __GFP_HIGH);
> if (!bio)
> return -ENOMEM;
>
> diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
> index 8bb0136..eff9129 100644
> --- a/fs/btrfs/inode.c
> +++ b/fs/btrfs/inode.c
> @@ -7943,8 +7943,7 @@ out:
> static struct bio *btrfs_dio_bio_alloc(struct block_device *bdev,
> u64 first_sector, gfp_t gfp_flags)
> {
> - int nr_vecs = bio_get_nr_vecs(bdev);
> - return btrfs_bio_alloc(bdev, first_sector, nr_vecs, gfp_flags);
> + return btrfs_bio_alloc(bdev, first_sector, BIO_MAX_PAGES, gfp_flags);
> }
>
> static inline int btrfs_lookup_and_bind_dio_csum(struct btrfs_root *root,
> diff --git a/fs/btrfs/scrub.c b/fs/btrfs/scrub.c
> index ab58115..00b828a 100644
> --- a/fs/btrfs/scrub.c
> +++ b/fs/btrfs/scrub.c
> @@ -454,27 +454,14 @@ struct scrub_ctx *scrub_setup_ctx(struct btrfs_device *dev, int is_dev_replace)
> struct scrub_ctx *sctx;
> int i;
> struct btrfs_fs_info *fs_info = dev->dev_root->fs_info;
> - int pages_per_rd_bio;
> int ret;
>
> - /*
> - * the setting of pages_per_rd_bio is correct for scrub but might
> - * be wrong for the dev_replace code where we might read from
> - * different devices in the initial huge bios. However, that
> - * code is able to correctly handle the case when adding a page
> - * to a bio fails.
> - */
> - if (dev->bdev)
> - pages_per_rd_bio = min_t(int, SCRUB_PAGES_PER_RD_BIO,
> - bio_get_nr_vecs(dev->bdev));
> - else
> - pages_per_rd_bio = SCRUB_PAGES_PER_RD_BIO;
> sctx = kzalloc(sizeof(*sctx), GFP_NOFS);
> if (!sctx)
> goto nomem;
> atomic_set(&sctx->refs, 1);
> sctx->is_dev_replace = is_dev_replace;
> - sctx->pages_per_rd_bio = pages_per_rd_bio;
> + sctx->pages_per_rd_bio = SCRUB_PAGES_PER_RD_BIO;
> sctx->curr = -1;
> sctx->dev_root = dev->dev_root;
> for (i = 0; i < SCRUB_BIOS_PER_SCTX; ++i) {
> @@ -3875,8 +3862,7 @@ static int scrub_setup_wr_ctx(struct scrub_ctx *sctx,
> return 0;
>
> WARN_ON(!dev->bdev);
> - wr_ctx->pages_per_wr_bio = min_t(int, SCRUB_PAGES_PER_WR_BIO,
> - bio_get_nr_vecs(dev->bdev));
> + wr_ctx->pages_per_wr_bio = SCRUB_PAGES_PER_WR_BIO;
> wr_ctx->tgtdev = dev;
> atomic_set(&wr_ctx->flush_all_writes, 0);
> return 0;
> diff --git a/fs/direct-io.c b/fs/direct-io.c
> index 745d234..89baebe 100644
> --- a/fs/direct-io.c
> +++ b/fs/direct-io.c
> @@ -653,7 +653,7 @@ static inline int dio_new_bio(struct dio *dio, struct dio_submit *sdio,
> if (ret)
> goto out;
> sector = start_sector << (sdio->blkbits - 9);
> - nr_pages = min(sdio->pages_in_io, bio_get_nr_vecs(map_bh->b_bdev));
> + nr_pages = min(sdio->pages_in_io, BIO_MAX_PAGES);
> BUG_ON(nr_pages <= 0);
> dio_bio_alloc(dio, sdio, map_bh->b_bdev, sector, nr_pages);
> sdio->boundary = 0;
> diff --git a/fs/ext4/page-io.c b/fs/ext4/page-io.c
> index 5765f88..000682e 100644
> --- a/fs/ext4/page-io.c
> +++ b/fs/ext4/page-io.c
> @@ -376,10 +376,9 @@ void ext4_io_submit_init(struct ext4_io_submit *io,
> static int io_submit_init_bio(struct ext4_io_submit *io,
> struct buffer_head *bh)
> {
> - int nvecs = bio_get_nr_vecs(bh->b_bdev);
> struct bio *bio;
>
> - bio = bio_alloc(GFP_NOIO, min(nvecs, BIO_MAX_PAGES));
> + bio = bio_alloc(GFP_NOIO, BIO_MAX_PAGES);
> if (!bio)
> return -ENOMEM;
> bio->bi_iter.bi_sector = bh->b_blocknr * (bh->b_size >> 9);
> diff --git a/fs/ext4/readpage.c b/fs/ext4/readpage.c
> index 171b9ac..de1f96a 100644
> --- a/fs/ext4/readpage.c
> +++ b/fs/ext4/readpage.c
> @@ -284,7 +284,7 @@ int ext4_mpage_readpages(struct address_space *mapping,
> goto set_error_page;
> }
> bio = bio_alloc(GFP_KERNEL,
> - min_t(int, nr_pages, bio_get_nr_vecs(bdev)));
> + min_t(int, nr_pages, BIO_MAX_PAGES));
> if (!bio) {
> if (ctx)
> ext4_release_crypto_ctx(ctx);
> diff --git a/fs/gfs2/lops.c b/fs/gfs2/lops.c
> index 2c1ae86..64d3116 100644
> --- a/fs/gfs2/lops.c
> +++ b/fs/gfs2/lops.c
> @@ -261,18 +261,11 @@ void gfs2_log_flush_bio(struct gfs2_sbd *sdp, int rw)
> static struct bio *gfs2_log_alloc_bio(struct gfs2_sbd *sdp, u64 blkno)
> {
> struct super_block *sb = sdp->sd_vfs;
> - unsigned nrvecs = bio_get_nr_vecs(sb->s_bdev);
> struct bio *bio;
>
> BUG_ON(sdp->sd_log_bio);
>
> - while (1) {
> - bio = bio_alloc(GFP_NOIO, nrvecs);
> - if (likely(bio))
> - break;
> - nrvecs = max(nrvecs/2, 1U);
> - }
> -
> + bio = bio_alloc(GFP_NOIO, BIO_MAX_PAGES);
> bio->bi_iter.bi_sector = blkno * (sb->s_blocksize >> 9);
> bio->bi_bdev = sb->s_bdev;
> bio->bi_end_io = gfs2_end_log_write;
> diff --git a/fs/logfs/dev_bdev.c b/fs/logfs/dev_bdev.c
> index 76279e1..fbb5f95 100644
> --- a/fs/logfs/dev_bdev.c
> +++ b/fs/logfs/dev_bdev.c
> @@ -83,7 +83,7 @@ static int __bdev_writeseg(struct super_block *sb, u64 ofs, pgoff_t index,
> unsigned int max_pages;
> int i;
>
> - max_pages = min(nr_pages, (size_t) bio_get_nr_vecs(super->s_bdev));
> + max_pages = min(nr_pages, BIO_MAX_PAGES);
>
> bio = bio_alloc(GFP_NOFS, max_pages);
> BUG_ON(!bio);
> @@ -175,7 +175,7 @@ static int do_erase(struct super_block *sb, u64 ofs, pgoff_t index,
> unsigned int max_pages;
> int i;
>
> - max_pages = min(nr_pages, (size_t) bio_get_nr_vecs(super->s_bdev));
> + max_pages = min(nr_pages, BIO_MAX_PAGES);
>
> bio = bio_alloc(GFP_NOFS, max_pages);
> BUG_ON(!bio);
> diff --git a/fs/mpage.c b/fs/mpage.c
> index 3e79220..29bc6b7 100644
> --- a/fs/mpage.c
> +++ b/fs/mpage.c
> @@ -277,7 +277,7 @@ alloc_new:
> goto out;
> }
> bio = mpage_alloc(bdev, blocks[0] << (blkbits - 9),
> - min_t(int, nr_pages, bio_get_nr_vecs(bdev)),
> + min_t(int, nr_pages, BIO_MAX_PAGES),
> GFP_KERNEL);
> if (bio == NULL)
> goto confused;
> @@ -602,7 +602,7 @@ alloc_new:
> }
> }
> bio = mpage_alloc(bdev, blocks[0] << (blkbits - 9),
> - bio_get_nr_vecs(bdev), GFP_NOFS|__GFP_HIGH);
> + BIO_MAX_PAGES, GFP_NOFS|__GFP_HIGH);
> if (bio == NULL)
> goto confused;
> }
> diff --git a/fs/nilfs2/segbuf.c b/fs/nilfs2/segbuf.c
> index dc3a9efd..9be5a79 100644
> --- a/fs/nilfs2/segbuf.c
> +++ b/fs/nilfs2/segbuf.c
> @@ -427,7 +427,7 @@ static void nilfs_segbuf_prepare_write(struct nilfs_segment_buffer *segbuf,
> {
> wi->bio = NULL;
> wi->rest_blocks = segbuf->sb_sum.nblocks;
> - wi->max_pages = bio_get_nr_vecs(wi->nilfs->ns_bdev);
> + wi->max_pages = BIO_MAX_PAGES;
> wi->nr_vecs = min(wi->max_pages, wi->rest_blocks);
> wi->start = wi->end = 0;
> wi->blocknr = segbuf->sb_pseg_start;
> diff --git a/fs/xfs/xfs_aops.c b/fs/xfs/xfs_aops.c
> index a56960d..6339fe7 100644
> --- a/fs/xfs/xfs_aops.c
> +++ b/fs/xfs/xfs_aops.c
> @@ -383,8 +383,7 @@ STATIC struct bio *
> xfs_alloc_ioend_bio(
> struct buffer_head *bh)
> {
> - int nvecs = bio_get_nr_vecs(bh->b_bdev);
> - struct bio *bio = bio_alloc(GFP_NOIO, nvecs);
> + struct bio *bio = bio_alloc(GFP_NOIO, BIO_MAX_PAGES);
>
> ASSERT(bio->bi_private == NULL);
> bio->bi_iter.bi_sector = bh->b_blocknr * (bh->b_size >> 9);
> diff --git a/include/linux/bio.h b/include/linux/bio.h
> index da3a127..015422a 100644
> --- a/include/linux/bio.h
> +++ b/include/linux/bio.h
> @@ -427,7 +427,6 @@ void bio_chain(struct bio *, struct bio *);
> extern int bio_add_page(struct bio *, struct page *, unsigned int,unsigned int);
> extern int bio_add_pc_page(struct request_queue *, struct bio *, struct page *,
> unsigned int, unsigned int);
> -extern int bio_get_nr_vecs(struct block_device *);
> struct rq_map_data;
> extern struct bio *bio_map_user_iov(struct request_queue *,
> const struct iov_iter *, gfp_t);
> --
> 1.9.1
>
--
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