[PATCH v5 1/4] iomap: factor out iomap_dio_alignment helper

["Fengnan Chang" <changfengnan@bytedance.com>]

Extract the alignment computation from iomap_dio_bio_iter() into a
standalone helper so the upcoming simple direct I/O path can reuse it
without requiring a struct iomap_dio.

No functional change.

Signed-off-by: Fengnan Chang <changfengnan@bytedance.com>
---
 fs/iomap/direct-io.c | 13 +++++++++----
 1 file changed, 9 insertions(+), 4 deletions(-)

diff --git a/fs/iomap/direct-io.c b/fs/iomap/direct-io.c
index b485e3b191daf..487c4763f3fde 100644
--- a/fs/iomap/direct-io.c
+++ b/fs/iomap/direct-io.c
@@ -398,6 +398,14 @@ static ssize_t iomap_dio_bio_iter_one(struct iomap_iter *iter,
 	return ret;
 }
 
+static inline unsigned int iomap_dio_alignment(struct inode *inode,
+		struct block_device *bdev, unsigned int dio_flags)
+{
+	if (dio_flags & IOMAP_DIO_FSBLOCK_ALIGNED)
+		return i_blocksize(inode);
+	return bdev_logical_block_size(bdev);
+}
+
 static int iomap_dio_bio_iter(struct iomap_iter *iter, struct iomap_dio *dio)
 {
 	const struct iomap *iomap = &iter->iomap;
@@ -416,10 +424,7 @@ static int iomap_dio_bio_iter(struct iomap_iter *iter, struct iomap_dio *dio)
 	 * File systems that write out of place and always allocate new blocks
 	 * need each bio to be block aligned as that's the unit of allocation.
 	 */
-	if (dio->flags & IOMAP_DIO_FSBLOCK_ALIGNED)
-		alignment = fs_block_size;
-	else
-		alignment = bdev_logical_block_size(iomap->bdev);
+	alignment = iomap_dio_alignment(inode, iomap->bdev, dio->flags);
 
 	if ((pos | length) & (alignment - 1))
 		return -EINVAL;
-- 
2.39.5 (Apple Git-154)