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    SubjectRe: [PATCH V12 16/20] block: enable multipage bvecs
    On Mon, Nov 26, 2018 at 10:17:16AM +0800, Ming Lei wrote:
    > This patch pulls the trigger for multi-page bvecs.

    Reviewed-by: Omar Sandoval <osandov@fb.com>

    > Signed-off-by: Ming Lei <ming.lei@redhat.com>
    > ---
    > block/bio.c | 22 +++++++++++++++-------
    > fs/iomap.c | 4 ++--
    > fs/xfs/xfs_aops.c | 4 ++--
    > include/linux/bio.h | 2 +-
    > 4 files changed, 20 insertions(+), 12 deletions(-)
    >
    > diff --git a/block/bio.c b/block/bio.c
    > index 75fde30af51f..8bf9338d4783 100644
    > --- a/block/bio.c
    > +++ b/block/bio.c
    > @@ -753,6 +753,8 @@ EXPORT_SYMBOL(bio_add_pc_page);
    > * @page: page to add
    > * @len: length of the data to add
    > * @off: offset of the data in @page
    > + * @same_page: if %true only merge if the new data is in the same physical
    > + * page as the last segment of the bio.
    > *
    > * Try to add the data at @page + @off to the last bvec of @bio. This is a
    > * a useful optimisation for file systems with a block size smaller than the
    > @@ -761,19 +763,25 @@ EXPORT_SYMBOL(bio_add_pc_page);
    > * Return %true on success or %false on failure.
    > */
    > bool __bio_try_merge_page(struct bio *bio, struct page *page,
    > - unsigned int len, unsigned int off)
    > + unsigned int len, unsigned int off, bool same_page)
    > {
    > if (WARN_ON_ONCE(bio_flagged(bio, BIO_CLONED)))
    > return false;
    >
    > if (bio->bi_vcnt > 0) {
    > struct bio_vec *bv = &bio->bi_io_vec[bio->bi_vcnt - 1];
    > + phys_addr_t vec_end_addr = page_to_phys(bv->bv_page) +
    > + bv->bv_offset + bv->bv_len;
    > + phys_addr_t page_addr = page_to_phys(page);
    >
    > - if (page == bv->bv_page && off == bv->bv_offset + bv->bv_len) {
    > - bv->bv_len += len;
    > - bio->bi_iter.bi_size += len;
    > - return true;
    > - }
    > + if (vec_end_addr != page_addr + off)
    > + return false;
    > + if (same_page && ((vec_end_addr - 1) & PAGE_MASK) != page_addr)
    > + return false;
    > +
    > + bv->bv_len += len;
    > + bio->bi_iter.bi_size += len;
    > + return true;
    > }
    > return false;
    > }
    > @@ -819,7 +827,7 @@ EXPORT_SYMBOL_GPL(__bio_add_page);
    > int bio_add_page(struct bio *bio, struct page *page,
    > unsigned int len, unsigned int offset)
    > {
    > - if (!__bio_try_merge_page(bio, page, len, offset)) {
    > + if (!__bio_try_merge_page(bio, page, len, offset, false)) {
    > if (bio_full(bio))
    > return 0;
    > __bio_add_page(bio, page, len, offset);
    > diff --git a/fs/iomap.c b/fs/iomap.c
    > index 1f648d098a3b..ec5527b0fba4 100644
    > --- a/fs/iomap.c
    > +++ b/fs/iomap.c
    > @@ -313,7 +313,7 @@ iomap_readpage_actor(struct inode *inode, loff_t pos, loff_t length, void *data,
    > */
    > sector = iomap_sector(iomap, pos);
    > if (ctx->bio && bio_end_sector(ctx->bio) == sector) {
    > - if (__bio_try_merge_page(ctx->bio, page, plen, poff))
    > + if (__bio_try_merge_page(ctx->bio, page, plen, poff, true))
    > goto done;
    > is_contig = true;
    > }
    > @@ -344,7 +344,7 @@ iomap_readpage_actor(struct inode *inode, loff_t pos, loff_t length, void *data,
    > ctx->bio->bi_end_io = iomap_read_end_io;
    > }
    >
    > - __bio_add_page(ctx->bio, page, plen, poff);
    > + bio_add_page(ctx->bio, page, plen, poff);
    > done:
    > /*
    > * Move the caller beyond our range so that it keeps making progress.
    > diff --git a/fs/xfs/xfs_aops.c b/fs/xfs/xfs_aops.c
    > index 1f1829e506e8..b9fd44168f61 100644
    > --- a/fs/xfs/xfs_aops.c
    > +++ b/fs/xfs/xfs_aops.c
    > @@ -616,12 +616,12 @@ xfs_add_to_ioend(
    > bdev, sector);
    > }
    >
    > - if (!__bio_try_merge_page(wpc->ioend->io_bio, page, len, poff)) {
    > + if (!__bio_try_merge_page(wpc->ioend->io_bio, page, len, poff, true)) {
    > if (iop)
    > atomic_inc(&iop->write_count);
    > if (bio_full(wpc->ioend->io_bio))
    > xfs_chain_bio(wpc->ioend, wbc, bdev, sector);
    > - __bio_add_page(wpc->ioend->io_bio, page, len, poff);
    > + bio_add_page(wpc->ioend->io_bio, page, len, poff);
    > }
    >
    > wpc->ioend->io_size += len;
    > diff --git a/include/linux/bio.h b/include/linux/bio.h
    > index c35997dd02c2..5505f74aef8b 100644
    > --- a/include/linux/bio.h
    > +++ b/include/linux/bio.h
    > @@ -441,7 +441,7 @@ 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);
    > bool __bio_try_merge_page(struct bio *bio, struct page *page,
    > - unsigned int len, unsigned int off);
    > + unsigned int len, unsigned int off, bool same_page);
    > void __bio_add_page(struct bio *bio, struct page *page,
    > unsigned int len, unsigned int off);
    > int bio_iov_iter_get_pages(struct bio *bio, struct iov_iter *iter);
    > --
    > 2.9.5
    >

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