Move ifs read_bytes_pending increment logic into a separate helper,
iomap_start_folio_read(), which will be needed later on by
caller-provided read callbacks (added in a later commit) for
read/readahead. This is the counterpart to the currently existing
iomap_finish_folio_read().

Make iomap_start_folio_read() and iomap_finish_folio_read() publicly
accessible. These need to be accessible in order for caller-provided
read callbacks to use.

Signed-off-by: Joanne Koong <joannelkoong@gmail.com>
Reviewed-by: "Darrick J. Wong" <djwong@kernel.org>
---
 fs/iomap/buffered-io.c | 26 +++++++++++++++++---------
 include/linux/iomap.h  |  3 +++
 2 files changed, 20 insertions(+), 9 deletions(-)

diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c
index 008042108c68..50de09426c96 100644
--- a/fs/iomap/buffered-io.c
+++ b/fs/iomap/buffered-io.c
@@ -317,9 +317,20 @@ static int iomap_read_inline_data(const struct iomap_iter *iter,
 	return 0;
 }
 
-#ifdef CONFIG_BLOCK
-static void iomap_finish_folio_read(struct folio *folio, size_t off,
-		size_t len, int error)
+void iomap_start_folio_read(struct folio *folio, size_t len)
+{
+	struct iomap_folio_state *ifs = folio->private;
+
+	if (ifs) {
+		spin_lock_irq(&ifs->state_lock);
+		ifs->read_bytes_pending += len;
+		spin_unlock_irq(&ifs->state_lock);
+	}
+}
+EXPORT_SYMBOL_GPL(iomap_start_folio_read);
+
+void iomap_finish_folio_read(struct folio *folio, size_t off, size_t len,
+		int error)
 {
 	struct iomap_folio_state *ifs = folio->private;
 	bool uptodate = !error;
@@ -339,7 +350,9 @@ static void iomap_finish_folio_read(struct folio *folio, size_t off,
 	if (finished)
 		folio_end_read(folio, uptodate);
 }
+EXPORT_SYMBOL_GPL(iomap_finish_folio_read);
 
+#ifdef CONFIG_BLOCK
 static void iomap_read_end_io(struct bio *bio)
 {
 	int error = blk_status_to_errno(bio->bi_status);
@@ -381,18 +394,13 @@ static void iomap_read_folio_range_bio_async(const struct iomap_iter *iter,
 {
 	struct folio *folio = ctx->cur_folio;
 	const struct iomap *iomap = &iter->iomap;
-	struct iomap_folio_state *ifs = folio->private;
 	size_t poff = offset_in_folio(folio, pos);
 	loff_t length = iomap_length(iter);
 	sector_t sector;
 	struct bio *bio = ctx->private;
 
 	ctx->folio_owned = true;
-	if (ifs) {
-		spin_lock_irq(&ifs->state_lock);
-		ifs->read_bytes_pending += plen;
-		spin_unlock_irq(&ifs->state_lock);
-	}
+	iomap_start_folio_read(folio, plen);
 
 	sector = iomap_sector(iomap, pos);
 	if (!bio || bio_end_sector(bio) != sector ||
diff --git a/include/linux/iomap.h b/include/linux/iomap.h
index 73dceabc21c8..0938c4a57f4c 100644
--- a/include/linux/iomap.h
+++ b/include/linux/iomap.h
@@ -467,6 +467,9 @@ ssize_t iomap_add_to_ioend(struct iomap_writepage_ctx *wpc, struct folio *folio,
 		loff_t pos, loff_t end_pos, unsigned int dirty_len);
 int iomap_ioend_writeback_submit(struct iomap_writepage_ctx *wpc, int error);
 
+void iomap_start_folio_read(struct folio *folio, size_t len);
+void iomap_finish_folio_read(struct folio *folio, size_t off, size_t len,
+		int error);
 void iomap_start_folio_write(struct inode *inode, struct folio *folio,
 		size_t len);
 void iomap_finish_folio_write(struct inode *inode, struct folio *folio,
-- 
2.47.3