[PATCH 11/15] iomap: use a function pointer for dio submits

[Goldwyn Rodrigues]

From: Goldwyn Rodrigues <rgold...@suse.com>

This helps filesystems to perform tasks on the bio while
submitting for I/O. This could be post-write operations
such as data CRC or data replication for fs-handled RAID.

Signed-off-by: Goldwyn Rodrigues <rgold...@suse.com>
---
 fs/iomap/direct-io.c  | 16 +++++++++++-----
 include/linux/iomap.h |  2 ++
 2 files changed, 13 insertions(+), 5 deletions(-)

diff --git a/fs/iomap/direct-io.c b/fs/iomap/direct-io.c
index e3ccbf7daaae..2923b02c1d57 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 (dio->dops && dio->dops->submit_io) {
+               dio->dops->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)
@@ -191,7 +197,7 @@ 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
@@ -297,11 +303,11 @@ 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 7fdb09925740..1bcb2f14bd9a 100644
--- a/include/linux/iomap.h
+++ b/include/linux/iomap.h
@@ -196,6 +196,8 @@ sector_t iomap_bmap(struct address_space *mapping, sector_t 
bno,
 struct iomap_dio_ops {
        int (*end_io)(struct kiocb *iocb, ssize_t size, int error,
                      unsigned flags);
+       void (*submit_io)(struct bio *bio, struct inode *inode,
+                         loff_t file_offset);
 };
 
 ssize_t iomap_dio_rw(struct kiocb *iocb, struct iov_iter *iter,
-- 
2.16.4