diff --git a/block/bio.c b/block/bio.c
index acefd2be1cd97ed9c00ba04eb3ddef14279f501e..a1c74f10d604a535b0740e3c4051b33b71a0435a 100644
--- a/block/bio.c
+++ b/block/bio.c
@@ -547,6 +547,16 @@ void zero_fill_bio_iter(struct bio *bio, struct bvec_iter start)
 }
 EXPORT_SYMBOL(zero_fill_bio_iter);
 
+/**
+ * bio_truncate - truncate the bio to small size of @new_size
+ * @bio:	the bio to be truncated
+ * @new_size:	new size for truncating the bio
+ *
+ * Description:
+ *   Truncate the bio to new size of @new_size. If bio_op(bio) is
+ *   REQ_OP_READ, zero the truncated part. This function should only
+ *   be used for handling corner cases, such as bio eod.
+ */
 void bio_truncate(struct bio *bio, unsigned new_size)
 {
 	struct bio_vec bv;
@@ -557,7 +567,7 @@ void bio_truncate(struct bio *bio, unsigned new_size)
 	if (new_size >= bio->bi_iter.bi_size)
 		return;
 
-	if (bio_data_dir(bio) != READ)
+	if (bio_op(bio) != REQ_OP_READ)
 		goto exit;
 
 	bio_for_each_segment(bv, bio, iter) {
diff --git a/fs/buffer.c b/fs/buffer.c
index 6be882a23758bdf26e33da31a0fa9ca65c30b28b..af88734d1d38b192e74d8c3721a6362a5042e122 100644
--- a/fs/buffer.c
+++ b/fs/buffer.c
@@ -2990,7 +2990,7 @@ static void end_bio_bh_io_sync(struct bio *bio)
  * errors, this only handles the "we need to be able to
  * do IO at the final sector" case.
  */
-void guard_bio_eod(int op, struct bio *bio)
+void guard_bio_eod(struct bio *bio)
 {
 	sector_t maxsector;
 	struct hd_struct *part;
@@ -3059,15 +3059,15 @@ static int submit_bh_wbc(int op, int op_flags, struct buffer_head *bh,
 	bio->bi_end_io = end_bio_bh_io_sync;
 	bio->bi_private = bh;
 
-	/* Take care of bh's that straddle the end of the device */
-	guard_bio_eod(op, bio);
-
 	if (buffer_meta(bh))
 		op_flags |= REQ_META;
 	if (buffer_prio(bh))
 		op_flags |= REQ_PRIO;
 	bio_set_op_attrs(bio, op, op_flags);
 
+	/* Take care of bh's that straddle the end of the device */
+	guard_bio_eod(bio);
+
 	submit_bio(bio);
 	return 0;
 }
diff --git a/fs/internal.h b/fs/internal.h
index 73e9829245f13123c7c32f383bf93021ff6a17d1..e63939e6443923e770841a3599887d585b2d685e 100644
--- a/fs/internal.h
+++ b/fs/internal.h
@@ -40,7 +40,7 @@ static inline int __sync_blockdev(struct block_device *bdev, int wait)
 /*
  * buffer.c
  */
-extern void guard_bio_eod(int rw, struct bio *bio);
+extern void guard_bio_eod(struct bio *bio);
 extern int __block_write_begin_int(struct page *page, loff_t pos, unsigned len,
 		get_block_t *get_block, struct iomap *iomap);
 void __generic_write_end(struct inode *inode, loff_t pos, unsigned copied,
diff --git a/fs/mpage.c b/fs/mpage.c
index c820dc9bebab6143a759c829ed478cb90931048a..fb2ff971c66b639b2d85a9bda4e297ae9affd6fb 100644
--- a/fs/mpage.c
+++ b/fs/mpage.c
@@ -62,7 +62,7 @@ static struct bio *mpage_bio_submit(int op, int op_flags, struct bio *bio)
 {
 	bio->bi_end_io = mpage_end_io;
 	bio_set_op_attrs(bio, op, op_flags);
-	guard_bio_eod(op, bio);
+	guard_bio_eod(bio);
 	submit_bio(bio);
 	return NULL;
 }