On 11/12/2013 01:15 PM, Chao Yu wrote:
> For better read performance, we add a new function to support for merging contiguous read as the one for write.
Nice shot!
>
> Signed-off-by: Chao Yu <chao2.yu@xxxxxxxxxxx>
Acked-by: Gu Zheng <guz.fnst@xxxxxxxxxxxxxx>
> ---
> fs/f2fs/data.c | 45 +++++++++++++++++++++++++++++++++++++++++++++
> fs/f2fs/f2fs.h | 2 ++
> 2 files changed, 47 insertions(+)
>
> diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
> index aa3438c..f30060b 100644
> --- a/fs/f2fs/data.c
> +++ b/fs/f2fs/data.c
> @@ -404,6 +404,51 @@ int f2fs_readpage(struct f2fs_sb_info *sbi, struct page *page,
> return 0;
> }
>
> +void f2fs_submit_read_bio(struct f2fs_sb_info *sbi, int rw)
> +{
> + down_read(&sbi->bio_sem);
> + if (sbi->read_bio) {
> + submit_bio(rw, sbi->read_bio);
> + sbi->read_bio = NULL;
> + }
> + up_read(&sbi->bio_sem);
> +}
> +
> +void submit_read_page(struct f2fs_sb_info *sbi, struct page *page,
> + block_t blk_addr, int rw)
> +{
> + struct block_device *bdev = sbi->sb->s_bdev;
> + int bio_blocks;
> +
> + verify_block_addr(sbi, blk_addr);
> +
> + down_read(&sbi->bio_sem);
> +
> + if (sbi->read_bio && sbi->last_read_block != blk_addr - 1) {
> + submit_bio(rw, sbi->read_bio);
> + sbi->read_bio = NULL;
> + }
> +
> +alloc_new:
> + if (sbi->read_bio == NULL) {
> + bio_blocks = MAX_BIO_BLOCKS(max_hw_blocks(sbi));
> + sbi->read_bio = f2fs_bio_alloc(bdev, bio_blocks);
> + sbi->read_bio->bi_sector = SECTOR_FROM_BLOCK(sbi, blk_addr);
> + sbi->read_bio->bi_end_io = read_end_io;
> + }
> +
> + if (bio_add_page(sbi->read_bio, page, PAGE_CACHE_SIZE, 0) <
> + PAGE_CACHE_SIZE) {
> + submit_bio(rw, sbi->read_bio);
> + sbi->read_bio = NULL;
> + goto alloc_new;
> + }
> +
> + sbi->last_read_block = blk_addr;
> +
> + up_read(&sbi->bio_sem);
> +}
> +
> /*
> * This function should be used by the data read flow only where it
> * does not check the "create" flag that indicates block allocation.
> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
> index 89dc750..0afdcec 100644
> --- a/fs/f2fs/f2fs.h
> +++ b/fs/f2fs/f2fs.h
> @@ -359,6 +359,8 @@ struct f2fs_sb_info {
>
> /* for segment-related operations */
> struct f2fs_sm_info *sm_info; /* segment manager */
> + struct bio *read_bio; /* read bios to merge */
> + sector_t last_read_block; /* last read block number */
> struct bio *bio[NR_PAGE_TYPE]; /* bios to merge */
> sector_t last_block_in_bio[NR_PAGE_TYPE]; /* last block number */
> struct rw_semaphore bio_sem; /* IO semaphore */
--
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