block: Add bio_max_segs

It's often inconvenient to use BIO_MAX_PAGES due to min() requiring the
sign to be the same.  Introduce bio_max_segs() and change BIO_MAX_PAGES to
be unsigned to make it easier for the users.

Reviewed-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

11 files changed, 19 insertions, 25 deletions

diff --git a/fs/block_dev.c b/fs/block_dev.c
index ec26179c8062..0f95ff343d6b 100644
--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -221,7 +221,7 @@ static void blkdev_bio_end_io_simple(struct bio *bio)
 
 static ssize_t
 __blkdev_direct_IO_simple(struct kiocb *iocb, struct iov_iter *iter,
-		int nr_pages)
+		unsigned int nr_pages)
 {
 	struct file *file = iocb->ki_filp;
 	struct block_device *bdev = I_BDEV(bdev_file_inode(file));
@@ -355,8 +355,8 @@ static void blkdev_bio_end_io(struct bio *bio)
 	}
 }
 
-static ssize_t
-__blkdev_direct_IO(struct kiocb *iocb, struct iov_iter *iter, int nr_pages)
+static ssize_t __blkdev_direct_IO(struct kiocb *iocb, struct iov_iter *iter,
+		unsigned int nr_pages)
 {
 	struct file *file = iocb->ki_filp;
 	struct inode *inode = bdev_file_inode(file);
@@ -486,7 +486,7 @@ __blkdev_direct_IO(struct kiocb *iocb, struct iov_iter *iter, int nr_pages)
 static ssize_t
 blkdev_direct_IO(struct kiocb *iocb, struct iov_iter *iter)
 {
-	int nr_pages;
+	unsigned int nr_pages;
 
 	if (!iov_iter_count(iter))
 		return 0;
@@ -495,7 +495,7 @@ blkdev_direct_IO(struct kiocb *iocb, struct iov_iter *iter)
 	if (is_sync_kiocb(iocb) && nr_pages <= BIO_MAX_PAGES)
 		return __blkdev_direct_IO_simple(iocb, iter, nr_pages);
 
-	return __blkdev_direct_IO(iocb, iter, min(nr_pages, BIO_MAX_PAGES));
+	return __blkdev_direct_IO(iocb, iter, bio_max_segs(nr_pages));
 }
 
 static __init int blkdev_init(void)
diff --git a/fs/direct-io.c b/fs/direct-io.c
index aa1083ecd623..c9639b4166c2 100644
--- a/fs/direct-io.c
+++ b/fs/direct-io.c
@@ -695,7 +695,7 @@ static inline int dio_new_bio(struct dio *dio, struct dio_submit *sdio,
 	if (ret)
 		goto out;
 	sector = start_sector << (sdio->blkbits - 9);
-	nr_pages = min(sdio->pages_in_io, BIO_MAX_PAGES);
+	nr_pages = bio_max_segs(sdio->pages_in_io);
 	BUG_ON(nr_pages <= 0);
 	dio_bio_alloc(dio, sdio, map_bh->b_bdev, sector, nr_pages);
 	sdio->boundary = 0;
diff --git a/fs/erofs/data.c b/fs/erofs/data.c
index ea4f693bee22..f88851c5c250 100644
--- a/fs/erofs/data.c
+++ b/fs/erofs/data.c
@@ -215,10 +215,8 @@ submit_bio_retry:
 		/* max # of continuous pages */
 		if (nblocks > DIV_ROUND_UP(map.m_plen, PAGE_SIZE))
 			nblocks = DIV_ROUND_UP(map.m_plen, PAGE_SIZE);
-		if (nblocks > BIO_MAX_PAGES)
-			nblocks = BIO_MAX_PAGES;
 
-		bio = bio_alloc(GFP_NOIO, nblocks);
+		bio = bio_alloc(GFP_NOIO, bio_max_segs(nblocks));
 
 		bio->bi_end_io = erofs_readendio;
 		bio_set_dev(bio, sb->s_bdev);
diff --git a/fs/ext4/readpage.c b/fs/ext4/readpage.c
index f014c5e473a9..3db923403505 100644
--- a/fs/ext4/readpage.c
+++ b/fs/ext4/readpage.c
@@ -371,8 +371,7 @@ int ext4_mpage_readpages(struct inode *inode,
 			 * bio_alloc will _always_ be able to allocate a bio if
 			 * __GFP_DIRECT_RECLAIM is set, see bio_alloc_bioset().
 			 */
-			bio = bio_alloc(GFP_KERNEL,
-				min_t(int, nr_pages, BIO_MAX_PAGES));
+			bio = bio_alloc(GFP_KERNEL, bio_max_segs(nr_pages));
 			fscrypt_set_bio_crypt_ctx(bio, inode, next_block,
 						  GFP_KERNEL);
 			ext4_set_bio_post_read_ctx(bio, inode, page->index);
diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
index b9721c8f116c..7c95818639a6 100644
--- a/fs/f2fs/data.c
+++ b/fs/f2fs/data.c
@@ -969,8 +969,7 @@ static struct bio *f2fs_grab_read_bio(struct inode *inode, block_t blkaddr,
 	unsigned int post_read_steps = 0;
 
 	bio = bio_alloc_bioset(for_write ? GFP_NOIO : GFP_KERNEL,
-			       min_t(int, nr_pages, BIO_MAX_PAGES),
-			       &f2fs_bioset);
+			       bio_max_segs(nr_pages), &f2fs_bioset);
 	if (!bio)
 		return ERR_PTR(-ENOMEM);
 
diff --git a/fs/f2fs/node.c b/fs/f2fs/node.c
index a8a0fb890e8d..4b0e2e3c2c88 100644
--- a/fs/f2fs/node.c
+++ b/fs/f2fs/node.c
@@ -2747,7 +2747,7 @@ int f2fs_restore_node_summary(struct f2fs_sb_info *sbi,
 	sum_entry = &sum->entries[0];
 
 	for (i = 0; i < last_offset; i += nrpages, addr += nrpages) {
-		nrpages = min(last_offset - i, BIO_MAX_PAGES);
+		nrpages = bio_max_segs(last_offset - i);
 
 		/* readahead node pages */
 		f2fs_ra_meta_pages(sbi, addr, nrpages, META_POR, true);
diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c
index 16a1e82e3aeb..0d9d1a6a947e 100644
--- a/fs/iomap/buffered-io.c
+++ b/fs/iomap/buffered-io.c
@@ -278,14 +278,14 @@ iomap_readpage_actor(struct inode *inode, loff_t pos, loff_t length, void *data,
 	if (!is_contig || bio_full(ctx->bio, plen)) {
 		gfp_t gfp = mapping_gfp_constraint(page->mapping, GFP_KERNEL);
 		gfp_t orig_gfp = gfp;
-		int nr_vecs = (length + PAGE_SIZE - 1) >> PAGE_SHIFT;
+		unsigned int nr_vecs = DIV_ROUND_UP(length, PAGE_SIZE);
 
 		if (ctx->bio)
 			submit_bio(ctx->bio);
 
 		if (ctx->rac) /* same as readahead_gfp_mask */
 			gfp |= __GFP_NORETRY | __GFP_NOWARN;
-		ctx->bio = bio_alloc(gfp, min(BIO_MAX_PAGES, nr_vecs));
+		ctx->bio = bio_alloc(gfp, bio_max_segs(nr_vecs));
 		/*
 		 * If the bio_alloc fails, try it again for a single page to
 		 * avoid having to deal with partial page reads.  This emulates
diff --git a/fs/mpage.c b/fs/mpage.c
index 830e6cc2a9e7..961234d68779 100644
--- a/fs/mpage.c
+++ b/fs/mpage.c
@@ -304,9 +304,7 @@ alloc_new:
 				goto out;
 		}
 		args->bio = mpage_alloc(bdev, blocks[0] << (blkbits - 9),
-					min_t(int, args->nr_pages,
-					      BIO_MAX_PAGES),
-					gfp);
+					bio_max_segs(args->nr_pages), gfp);
 		if (args->bio == NULL)
 			goto confused;
 	}
diff --git a/fs/nfs/blocklayout/blocklayout.c b/fs/nfs/blocklayout/blocklayout.c
index 1a96ce28efb0..fe860c538747 100644
--- a/fs/nfs/blocklayout/blocklayout.c
+++ b/fs/nfs/blocklayout/blocklayout.c
@@ -115,13 +115,13 @@ bl_submit_bio(struct bio *bio)
 	return NULL;
 }
 
-static struct bio *
-bl_alloc_init_bio(int npg, struct block_device *bdev, sector_t disk_sector,
+static struct bio *bl_alloc_init_bio(unsigned int npg,
+		struct block_device *bdev, sector_t disk_sector,
 		bio_end_io_t end_io, struct parallel_io *par)
 {
 	struct bio *bio;
 
-	npg = min(npg, BIO_MAX_PAGES);
+	npg = bio_max_segs(npg);
 	bio = bio_alloc(GFP_NOIO, npg);
 	if (bio) {
 		bio->bi_iter.bi_sector = disk_sector;
diff --git a/fs/xfs/xfs_bio_io.c b/fs/xfs/xfs_bio_io.c
index e2148f2d5d6b..17f36db2f792 100644
--- a/fs/xfs/xfs_bio_io.c
+++ b/fs/xfs/xfs_bio_io.c
@@ -6,7 +6,7 @@
 
 static inline unsigned int bio_max_vecs(unsigned int count)
 {
-	return min_t(unsigned, howmany(count, PAGE_SIZE), BIO_MAX_PAGES);
+	return bio_max_segs(howmany(count, PAGE_SIZE));
 }
 
 int
diff --git a/fs/xfs/xfs_buf.c b/fs/xfs/xfs_buf.c
index f6e5235df7c9..37a1d12762d8 100644
--- a/fs/xfs/xfs_buf.c
+++ b/fs/xfs/xfs_buf.c
@@ -1480,7 +1480,7 @@ xfs_buf_ioapply_map(
 	int		op)
 {
 	int		page_index;
-	int		total_nr_pages = bp->b_page_count;
+	unsigned int	total_nr_pages = bp->b_page_count;
 	int		nr_pages;
 	struct bio	*bio;
 	sector_t	sector =  bp->b_maps[map].bm_bn;
@@ -1505,7 +1505,7 @@ xfs_buf_ioapply_map(
 
 next_chunk:
 	atomic_inc(&bp->b_io_remaining);
-	nr_pages = min(total_nr_pages, BIO_MAX_PAGES);
+	nr_pages = bio_max_segs(total_nr_pages);
 
 	bio = bio_alloc(GFP_NOIO, nr_pages);
 	bio_set_dev(bio, bp->b_target->bt_bdev);