[PATCH V2 1/2] f2fs: add a new function to support for merging contiguous read

[Chao Yu <chao2.yu@samsung.com>]

For better read performance, we add a new function to support for merging contiguous read as the one for write.

v1-->v2:
 o add declarations here as Gu Zheng suggested.

Signed-off-by: Chao Yu <chao2.yu@samsung.com>
Acked-by: Gu Zheng <guz.fnst@cn.fujitsu.com>
---
 fs/f2fs/data.c |   45 +++++++++++++++++++++++++++++++++++++++++++++
 fs/f2fs/f2fs.h |    4 ++++
 2 files changed, 49 insertions(+)

diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
index aa3438c..18107cb 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..bfe9d87 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 */
@@ -1111,6 +1113,8 @@ struct page *find_data_page(struct inode *, pgoff_t, bool);
 struct page *get_lock_data_page(struct inode *, pgoff_t);
 struct page *get_new_data_page(struct inode *, struct page *, pgoff_t, bool);
 int f2fs_readpage(struct f2fs_sb_info *, struct page *, block_t, int);
+void f2fs_submit_read_bio(struct f2fs_sb_info *, int);
+void submit_read_page(struct f2fs_sb_info *, struct page *, block_t, int);
 int do_write_data_page(struct page *);
 
 /*
-- 
1.7.9.5


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