f2fs: cleanup the f2fs_bio_alloc routine

Do cleanup more for better code readability.

- Change the parameter set of f2fs_bio_alloc()
  This function should allocate a bio only since it is not something like
  f2fs_bio_init(). Instead, the caller should initialize the allocated bio.

- Introduce SECTOR_FROM_BLOCK
  This macro translates a block address to its sector address.

Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
Reviewed-by: Namjae Jeon <namjae.jeon@samsung.com>

fs/f2fs/data.c

@@ -343,11 +343,12 @@ int f2fs_readpage(struct f2fs_sb_info *sbi, struct page *page,
 	down_read(&sbi->bio_sem);
 
 	/* Allocate a new bio */
-	bio = f2fs_bio_alloc(bdev, blk_addr << (sbi->log_blocksize - 9),
-				1, GFP_NOFS | __GFP_HIGH);
+	bio = f2fs_bio_alloc(bdev, 1);
 
 	/* Initialize the bio */
+	bio->bi_sector = SECTOR_FROM_BLOCK(sbi, blk_addr);
 	bio->bi_end_io = read_end_io;
+
 	if (bio_add_page(bio, page, PAGE_CACHE_SIZE, 0) < PAGE_CACHE_SIZE) {
 		kfree(bio->bi_private);
 		bio_put(bio);

fs/f2fs/f2fs.h

@@ -924,7 +924,7 @@ void clear_prefree_segments(struct f2fs_sb_info *);
 int npages_for_summary_flush(struct f2fs_sb_info *);
 void allocate_new_segments(struct f2fs_sb_info *);
 struct page *get_sum_page(struct f2fs_sb_info *, unsigned int);
-struct bio *f2fs_bio_alloc(struct block_device *, sector_t, int, gfp_t);
+struct bio *f2fs_bio_alloc(struct block_device *, int);
 void f2fs_submit_bio(struct f2fs_sb_info *, enum page_type, bool sync);
 int write_meta_page(struct f2fs_sb_info *, struct page *,
 					struct writeback_control *);

fs/f2fs/segment.c

@@ -643,23 +643,21 @@ static void f2fs_end_io_write(struct bio *bio, int err)
 	bio_put(bio);
 }
 
-struct bio *f2fs_bio_alloc(struct block_device *bdev, sector_t first_sector,
-					int nr_vecs, gfp_t gfp_flags)
+struct bio *f2fs_bio_alloc(struct block_device *bdev, int npages)
 {
 	struct bio *bio;
-
-	/* allocate new bio */
-	bio = bio_alloc(gfp_flags, nr_vecs);
-
-	bio->bi_bdev = bdev;
-	bio->bi_sector = first_sector;
+	struct bio_private *priv;
 retry:
-	bio->bi_private = kmalloc(sizeof(struct bio_private),
-					GFP_NOFS | __GFP_HIGH);
-	if (!bio->bi_private) {
+	priv = kmalloc(sizeof(struct bio_private), GFP_NOFS);
+	if (!priv) {
 		cond_resched();
 		goto retry;
 	}
+
+	/* No failure on bio allocation */
+	bio = bio_alloc(GFP_NOIO, npages);
+	bio->bi_bdev = bdev;
+	bio->bi_private = priv;
 	return bio;
 }
 
@@ -711,10 +709,15 @@ static void submit_write_page(struct f2fs_sb_info *sbi, struct page *page,
 	if (sbi->bio[type] && sbi->last_block_in_bio[type] != blk_addr - 1)
 		do_submit_bio(sbi, type, false);
 alloc_new:
-	if (sbi->bio[type] == NULL)
-		sbi->bio[type] = f2fs_bio_alloc(bdev,
-				blk_addr << (sbi->log_blocksize - 9),
-				bio_get_nr_vecs(bdev), GFP_NOFS | __GFP_HIGH);
+	if (sbi->bio[type] == NULL) {
+		sbi->bio[type] = f2fs_bio_alloc(bdev, bio_get_nr_vecs(bdev));
+		sbi->bio[type]->bi_sector = SECTOR_FROM_BLOCK(sbi, blk_addr);
+		/*
+		 * The end_io will be assigned at the sumbission phase.
+		 * Until then, let bio_add_page() merge consecutive IOs as much
+		 * as possible.
+		 */
+	}
 
 	if (bio_add_page(sbi->bio[type], page, PAGE_CACHE_SIZE, 0) <
 							PAGE_CACHE_SIZE) {

fs/f2fs/segment.h

@@ -82,6 +82,9 @@
 	(BITS_TO_LONGS(nr) * sizeof(unsigned long))
 #define TOTAL_SEGS(sbi)	(SM_I(sbi)->main_segments)
 
+#define SECTOR_FROM_BLOCK(sbi, blk_addr)				\
+	(blk_addr << ((sbi)->log_blocksize - F2FS_LOG_SECTOR_SIZE))
+
 /* during checkpoint, bio_private is used to synchronize the last bio */
 struct bio_private {
 	struct f2fs_sb_info *sbi;