[PATCH 10/13] iomap: use a function pointer for dio submits

[Goldwyn Rodrigues <rgoldwyn@xxxxxxx>]

From: Goldwyn Rodrigues <rgoldwyn@xxxxxxxx>

This helps filesystems to perform tasks on the bio while
submitting for I/O. Since btrfs requires the position
we are working on, pass pos to iomap_dio_submit_bio()

The correct place for submit_io() is not page_ops. Would it
better to rename the structure to something like iomap_io_ops
or put it directly under struct iomap?

Signed-off-by: Goldwyn Rodrigues <rgoldwyn@xxxxxxxx>
---
 fs/iomap/direct-io.c  | 16 +++++++++++-----
 include/linux/iomap.h |  1 +
 2 files changed, 12 insertions(+), 5 deletions(-)

diff --git a/fs/iomap/direct-io.c b/fs/iomap/direct-io.c
index 5279029c7a3c..a802e66bf11f 100644
--- a/fs/iomap/direct-io.c
+++ b/fs/iomap/direct-io.c
@@ -59,7 +59,7 @@ int iomap_dio_iopoll(struct kiocb *kiocb, bool spin)
 EXPORT_SYMBOL_GPL(iomap_dio_iopoll);
 
 static void iomap_dio_submit_bio(struct iomap_dio *dio, struct iomap *iomap,
-		struct bio *bio)
+		struct bio *bio, loff_t pos)
 {
 	atomic_inc(&dio->ref);
 
@@ -67,7 +67,13 @@ static void iomap_dio_submit_bio(struct iomap_dio *dio, struct iomap *iomap,
 		bio_set_polled(bio, dio->iocb);
 
 	dio->submit.last_queue = bdev_get_queue(iomap->bdev);
-	dio->submit.cookie = submit_bio(bio);
+	if (iomap->page_ops && iomap->page_ops->submit_io) {
+		iomap->page_ops->submit_io(bio, file_inode(dio->iocb->ki_filp),
+				pos);
+		dio->submit.cookie = BLK_QC_T_NONE;
+	} else {
+		dio->submit.cookie = submit_bio(bio);
+	}
 }
 
 static ssize_t iomap_dio_complete(struct iomap_dio *dio)
@@ -195,7 +201,7 @@ iomap_dio_zero(struct iomap_dio *dio, struct iomap *iomap, loff_t pos,
 	get_page(page);
 	__bio_add_page(bio, page, len, 0);
 	bio_set_op_attrs(bio, REQ_OP_WRITE, flags);
-	iomap_dio_submit_bio(dio, iomap, bio);
+	iomap_dio_submit_bio(dio, iomap, bio, pos);
 }
 
 static loff_t
@@ -301,11 +307,11 @@ iomap_dio_bio_actor(struct inode *inode, loff_t pos, loff_t length,
 		iov_iter_advance(dio->submit.iter, n);
 
 		dio->size += n;
-		pos += n;
 		copied += n;
 
 		nr_pages = iov_iter_npages(&iter, BIO_MAX_PAGES);
-		iomap_dio_submit_bio(dio, iomap, bio);
+		iomap_dio_submit_bio(dio, iomap, bio, pos);
+		pos += n;
 	} while (nr_pages);
 
 	/*
diff --git a/include/linux/iomap.h b/include/linux/iomap.h
index 5b2055e8ca8a..6617e4b6fb6d 100644
--- a/include/linux/iomap.h
+++ b/include/linux/iomap.h
@@ -92,6 +92,7 @@ struct iomap_page_ops {
 			struct iomap *iomap);
 	void (*page_done)(struct inode *inode, loff_t pos, unsigned copied,
 			struct page *page, struct iomap *iomap);
+	dio_submit_t 		*submit_io;
 };
 
 /*
-- 
2.16.4