Re: [PATCH 13/18] xfs: don't look at buffer heads in xfs_add_to_ioend

Brian Foster
2018-05-31T13:49:27Z

On Wed, May 30, 2018 at 12:00:08PM +0200, Christoph Hellwig wrote:
> Calculate all information for the bio based on the passed in information
> without requiring a buffer_head structure.
>
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---

Reviewed-by: Brian Foster <bfoster@redhat.com>

> fs/xfs/xfs_aops.c | 68 ++++++++++++++++++++++-------------------------
> 1 file changed, 32 insertions(+), 36 deletions(-)
>
> diff --git a/fs/xfs/xfs_aops.c b/fs/xfs/xfs_aops.c
> index 910b410e5a90..7d02d04d5a5b 100644
> --- a/fs/xfs/xfs_aops.c
> +++ b/fs/xfs/xfs_aops.c
> @@ -44,7 +44,6 @@ struct xfs_writepage_ctx {
> struct xfs_bmbt_irec imap;
> unsigned int io_type;
> struct xfs_ioend *ioend;
> - sector_t last_block;
> };
>
> void
> @@ -535,11 +534,6 @@ xfs_start_page_writeback(
> unlock_page(page);
> }
>
> -static inline int xfs_bio_add_buffer(struct bio *bio, struct buffer_head *bh)
> -{
> - return bio_add_page(bio, bh->b_page, bh->b_size, bh_offset(bh));
> -}
> -
> /*
> * Submit the bio for an ioend. We are passed an ioend with a bio attached to
> * it, and we submit that bio. The ioend may be used for multiple bio
> @@ -594,27 +588,20 @@ xfs_submit_ioend(
> return 0;
> }
>
> -static void
> -xfs_init_bio_from_bh(
> - struct bio *bio,
> - struct buffer_head *bh)
> -{
> - bio->bi_iter.bi_sector = bh->b_blocknr * (bh->b_size >> 9);
> - bio_set_dev(bio, bh->b_bdev);
> -}
> -
> static struct xfs_ioend *
> xfs_alloc_ioend(
> struct inode *inode,
> unsigned int type,
> xfs_off_t offset,
> - struct buffer_head *bh)
> + struct block_device *bdev,
> + sector_t sector)
> {
> struct xfs_ioend *ioend;
> struct bio *bio;
>
> bio = bio_alloc_bioset(GFP_NOFS, BIO_MAX_PAGES, xfs_ioend_bioset);
> - xfs_init_bio_from_bh(bio, bh);
> + bio_set_dev(bio, bdev);
> + bio->bi_iter.bi_sector = sector;
>
> ioend = container_of(bio, struct xfs_ioend, io_inline_bio);
> INIT_LIST_HEAD(&ioend->io_list);
> @@ -639,13 +626,14 @@ static void
> xfs_chain_bio(
> struct xfs_ioend *ioend,
> struct writeback_control *wbc,
> - struct buffer_head *bh)
> + struct block_device *bdev,
> + sector_t sector)
> {
> struct bio *new;
>
> new = bio_alloc(GFP_NOFS, BIO_MAX_PAGES);
> - xfs_init_bio_from_bh(new, bh);
> -
> + bio_set_dev(new, bdev);
> + new->bi_iter.bi_sector = sector;
> bio_chain(ioend->io_bio, new);
> bio_get(ioend->io_bio); /* for xfs_destroy_ioend */
> ioend->io_bio->bi_opf = REQ_OP_WRITE | wbc_to_write_flags(wbc);
> @@ -655,39 +643,45 @@ xfs_chain_bio(
> }
>
> /*
> - * Test to see if we've been building up a completion structure for
> - * earlier buffers -- if so, we try to append to this ioend if we
> - * can, otherwise we finish off any current ioend and start another.
> - * Return the ioend we finished off so that the caller can submit it
> - * once it has finished processing the dirty page.
> + * Test to see if we have an existing ioend structure that we could append to
> + * first, otherwise finish off the current ioend and start another.
> */
> STATIC void
> xfs_add_to_ioend(
> struct inode *inode,
> - struct buffer_head *bh,
> xfs_off_t offset,
> + struct page *page,
> struct xfs_writepage_ctx *wpc,
> struct writeback_control *wbc,
> struct list_head *iolist)
> {
> + struct xfs_inode *ip = XFS_I(inode);
> + struct xfs_mount *mp = ip->i_mount;
> + struct block_device *bdev = xfs_find_bdev_for_inode(inode);
> + unsigned len = i_blocksize(inode);
> + unsigned poff = offset & (PAGE_SIZE - 1);
> + sector_t sector;
> +
> + sector = xfs_fsb_to_db(ip, wpc->imap.br_startblock) +
> + ((offset - XFS_FSB_TO_B(mp, wpc->imap.br_startoff)) >> 9);
> +
> if (!wpc->ioend || wpc->io_type != wpc->ioend->io_type ||
> - bh->b_blocknr != wpc->last_block + 1 ||
> + sector != bio_end_sector(wpc->ioend->io_bio) ||
> offset != wpc->ioend->io_offset + wpc->ioend->io_size) {
> if (wpc->ioend)
> list_add(&wpc->ioend->io_list, iolist);
> - wpc->ioend = xfs_alloc_ioend(inode, wpc->io_type, offset, bh);
> + wpc->ioend = xfs_alloc_ioend(inode, wpc->io_type, offset,
> + bdev, sector);
> }
>
> /*
> - * If the buffer doesn't fit into the bio we need to allocate a new
> - * one. This shouldn't happen more than once for a given buffer.
> + * If the block doesn't fit into the bio we need to allocate a new
> + * one. This shouldn't happen more than once for a given block.
> */
> - while (xfs_bio_add_buffer(wpc->ioend->io_bio, bh) != bh->b_size)
> - xfs_chain_bio(wpc->ioend, wbc, bh);
> + while (bio_add_page(wpc->ioend->io_bio, page, len, poff) != len)
> + xfs_chain_bio(wpc->ioend, wbc, bdev, sector);
>
> - wpc->ioend->io_size += bh->b_size;
> - wpc->last_block = bh->b_blocknr;
> - xfs_start_buffer_writeback(bh);
> + wpc->ioend->io_size += len;
> }
>
> STATIC void
> @@ -883,7 +877,9 @@ xfs_writepage_map(
>
> lock_buffer(bh);
> xfs_map_at_offset(inode, bh, &wpc->imap, file_offset);
> - xfs_add_to_ioend(inode, bh, file_offset, wpc, wbc, &submit_list);
> + xfs_add_to_ioend(inode, file_offset, page, wpc, wbc,
> + &submit_list);
> + xfs_start_buffer_writeback(bh);
> count++;