f2fs: avoid allocating failure in bio_alloc

This patch add macro MAX_BIO_BLOCKS to limit value of npages in
f2fs_bio_alloc, it can avoid allocating failure in bio_alloc caused by
npages is larger than BIO_MAX_PAGES.
Signed-off-by: Yu Chao <chao2.yu@samsung.com>
Reviewed-by: Gu Zheng <guz.fnst@cn.fujitsu.com>
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>

fs/f2fs/segment.c

@@ -657,6 +657,7 @@ static void submit_write_page(struct f2fs_sb_info *sbi, struct page *page,
 				block_t blk_addr, enum page_type type)
 {
 	struct block_device *bdev = sbi->sb->s_bdev;
+	int bio_blocks;
 
 	verify_block_addr(sbi, blk_addr);
 
@@ -676,7 +677,8 @@ static void submit_write_page(struct f2fs_sb_info *sbi, struct page *page,
 			goto retry;
 		}
 
-		sbi->bio[type] = f2fs_bio_alloc(bdev, max_hw_blocks(sbi));
+		bio_blocks = MAX_BIO_BLOCKS(max_hw_blocks(sbi));
+		sbi->bio[type] = f2fs_bio_alloc(bdev, bio_blocks);
 		sbi->bio[type]->bi_sector = SECTOR_FROM_BLOCK(sbi, blk_addr);
 		sbi->bio[type]->bi_private = priv;
 		/*

fs/f2fs/segment.h

@@ -90,6 +90,8 @@
 	(blk_addr << ((sbi)->log_blocksize - F2FS_LOG_SECTOR_SIZE))
 #define SECTOR_TO_BLOCK(sbi, sectors)					\
 	(sectors >> ((sbi)->log_blocksize - F2FS_LOG_SECTOR_SIZE))
+#define MAX_BIO_BLOCKS(max_hw_blocks)					\
+	(min((int)max_hw_blocks, BIO_MAX_PAGES))
 
 /* during checkpoint, bio_private is used to synchronize the last bio */
 struct bio_private {