1 files changed, 45 insertions, 15 deletions

diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index eedcfb40c356..3b33e7afd8e4 100644
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -3084,6 +3084,48 @@ struct bio *btrfs_bio_clone_partial(struct bio *orig, int offset, int size)
 	return bio;
 }
 
+/**
+ * Attempt to add a page to bio
+ *
+ * @bio:	destination bio
+ * @page:	page to add to the bio
+ * @disk_bytenr:  offset of the new bio or to check whether we are adding
+ *                a contiguous page to the previous one
+ * @pg_offset:	starting offset in the page
+ * @size:	portion of page that we want to write
+ * @prev_bio_flags:  flags of previous bio to see if we can merge the current one
+ * @bio_flags:	flags of the current bio to see if we can merge them
+ * @return:	true if page was added, false otherwise
+ *
+ * Attempt to add a page to bio considering stripe alignment etc.
+ *
+ * Return true if successfully page added. Otherwise, return false.
+ */
+static bool btrfs_bio_add_page(struct bio *bio, struct page *page,
+			       u64 disk_bytenr, unsigned int size,
+			       unsigned int pg_offset,
+			       unsigned long prev_bio_flags,
+			       unsigned long bio_flags)
+{
+	const sector_t sector = disk_bytenr >> SECTOR_SHIFT;
+	bool contig;
+
+	if (prev_bio_flags != bio_flags)
+		return false;
+
+	if (prev_bio_flags & EXTENT_BIO_COMPRESSED)
+		contig = bio->bi_iter.bi_sector == sector;
+	else
+		contig = bio_end_sector(bio) == sector;
+	if (!contig)
+		return false;
+
+	if (btrfs_bio_fits_in_stripe(page, size, bio, bio_flags))
+		return false;
+
+	return bio_add_page(bio, page, size, pg_offset) == size;
+}
+
 /*
  * @opf:	bio REQ_OP_* and REQ_* flags as one value
  * @wbc:	optional writeback control for io accounting
@@ -3112,27 +3154,15 @@ static int submit_extent_page(unsigned int opf,
 	int ret = 0;
 	struct bio *bio;
 	size_t io_size = min_t(size_t, size, PAGE_SIZE);
-	sector_t sector = disk_bytenr >> 9;
 	struct extent_io_tree *tree = &BTRFS_I(page->mapping->host)->io_tree;
 
 	ASSERT(bio_ret);
 
 	if (*bio_ret) {
-		bool contig;
-		bool can_merge = true;
-
 		bio = *bio_ret;
-		if (prev_bio_flags & EXTENT_BIO_COMPRESSED)
-			contig = bio->bi_iter.bi_sector == sector;
-		else
-			contig = bio_end_sector(bio) == sector;
-
-		if (btrfs_bio_fits_in_stripe(page, io_size, bio, bio_flags))
-			can_merge = false;
-
-		if (prev_bio_flags != bio_flags || !contig || !can_merge ||
-		    force_bio_submit ||
-		    bio_add_page(bio, page, io_size, pg_offset) < io_size) {
+		if (force_bio_submit ||
+		    !btrfs_bio_add_page(bio, page, disk_bytenr, io_size,
+					pg_offset, prev_bio_flags, bio_flags)) {
 			ret = submit_one_bio(bio, mirror_num, prev_bio_flags);
 			if (ret < 0) {
 				*bio_ret = NULL;