From 725130bac5857ac035cf9f47d2973ee4e734db54 Mon Sep 17 00:00:00 2001 From: Liu Bo Date: Tue, 16 May 2017 09:51:39 -0700 Subject: [PATCH] Btrfs: use bio_clone_bioset_partial to simplify DIO submit Currently when mapping bio to limit bio to a single stripe length, we split bio by adding page to bio one by one, but later we don't modify the vector of bio at all, thus we can use bio_clone_fast to use the original bio vector directly. Signed-off-by: Liu Bo Reviewed-by: David Sterba Signed-off-by: David Sterba --- fs/btrfs/inode.c | 119 +++++++++++++++++++++---------------------------------- 1 file changed, 45 insertions(+), 74 deletions(-) diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c index c61881d..c2e9c51 100644 --- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -8380,16 +8380,6 @@ out: bio_put(bio); } -static struct bio *btrfs_dio_bio_alloc(struct block_device *bdev, - u64 first_sector, gfp_t gfp_flags) -{ - struct bio *bio; - bio = btrfs_bio_alloc(bdev, first_sector, BIO_MAX_PAGES, gfp_flags); - if (bio) - bio_associate_current(bio); - return bio; -} - static inline int btrfs_lookup_and_bind_dio_csum(struct inode *inode, struct btrfs_dio_private *dip, struct bio *bio, @@ -8479,24 +8469,23 @@ static int btrfs_submit_direct_hook(struct btrfs_dio_private *dip, struct btrfs_root *root = BTRFS_I(inode)->root; struct bio *bio; struct bio *orig_bio = dip->orig_bio; - struct bio_vec *bvec; u64 start_sector = orig_bio->bi_iter.bi_sector; u64 file_offset = dip->logical_offset; - u64 submit_len = 0; u64 map_length; - u32 blocksize = fs_info->sectorsize; int async_submit = 0; - int nr_sectors; + u64 submit_len; + int clone_offset = 0; + int clone_len; int ret; - int i, j; map_length = orig_bio->bi_iter.bi_size; + submit_len = map_length; ret = btrfs_map_block(fs_info, btrfs_op(orig_bio), start_sector << 9, &map_length, NULL, 0); if (ret) return -EIO; - if (map_length >= orig_bio->bi_iter.bi_size) { + if (map_length >= submit_len) { bio = orig_bio; dip->flags |= BTRFS_DIO_ORIG_BIO_SUBMITTED; goto submit; @@ -8508,70 +8497,52 @@ static int btrfs_submit_direct_hook(struct btrfs_dio_private *dip, else async_submit = 1; - bio = btrfs_dio_bio_alloc(orig_bio->bi_bdev, start_sector, GFP_NOFS); - if (!bio) - return -ENOMEM; - - bio->bi_opf = orig_bio->bi_opf; - bio->bi_private = dip; - bio->bi_end_io = btrfs_end_dio_bio; - btrfs_io_bio(bio)->logical = file_offset; + /* bio split */ + ASSERT(map_length <= INT_MAX); atomic_inc(&dip->pending_bios); + while (submit_len > 0) { + clone_len = min_t(int, submit_len, map_length); - bio_for_each_segment_all(bvec, orig_bio, j) { - nr_sectors = BTRFS_BYTES_TO_BLKS(fs_info, bvec->bv_len); - i = 0; -next_block: - if (unlikely(map_length < submit_len + blocksize || - bio_add_page(bio, bvec->bv_page, blocksize, - bvec->bv_offset + (i * blocksize)) < blocksize)) { - /* - * inc the count before we submit the bio so - * we know the end IO handler won't happen before - * we inc the count. Otherwise, the dip might get freed - * before we're done setting it up - */ - atomic_inc(&dip->pending_bios); - ret = __btrfs_submit_dio_bio(bio, inode, - file_offset, skip_sum, - async_submit); - if (ret) { - bio_put(bio); - atomic_dec(&dip->pending_bios); - goto out_err; - } - - start_sector += submit_len >> 9; - file_offset += submit_len; + /* + * This will never fail as it's passing GPF_NOFS and + * the allocation is backed by btrfs_bioset. + */ + bio = btrfs_bio_clone_partial(orig_bio, GFP_NOFS, clone_offset, + clone_len); + bio->bi_private = dip; + bio->bi_end_io = btrfs_end_dio_bio; + btrfs_io_bio(bio)->logical = file_offset; + + ASSERT(submit_len >= clone_len); + submit_len -= clone_len; + if (submit_len == 0) + break; - submit_len = 0; + /* + * Increase the count before we submit the bio so we know + * the end IO handler won't happen before we increase the + * count. Otherwise, the dip might get freed before we're + * done setting it up. + */ + atomic_inc(&dip->pending_bios); - bio = btrfs_dio_bio_alloc(orig_bio->bi_bdev, - start_sector, GFP_NOFS); - if (!bio) - goto out_err; - bio->bi_opf = orig_bio->bi_opf; - bio->bi_private = dip; - bio->bi_end_io = btrfs_end_dio_bio; - btrfs_io_bio(bio)->logical = file_offset; + ret = __btrfs_submit_dio_bio(bio, inode, file_offset, skip_sum, + async_submit); + if (ret) { + bio_put(bio); + atomic_dec(&dip->pending_bios); + goto out_err; + } - map_length = orig_bio->bi_iter.bi_size; - ret = btrfs_map_block(fs_info, btrfs_op(orig_bio), - start_sector << 9, - &map_length, NULL, 0); - if (ret) { - bio_put(bio); - goto out_err; - } + clone_offset += clone_len; + start_sector += clone_len >> 9; + file_offset += clone_len; - goto next_block; - } else { - submit_len += blocksize; - if (--nr_sectors) { - i++; - goto next_block; - } - } + map_length = submit_len; + ret = btrfs_map_block(fs_info, btrfs_op(orig_bio), + start_sector << 9, &map_length, NULL, 0); + if (ret) + goto out_err; } submit: -- 2.7.4