[PATCH 5/6] xfs: add DAX IO path support

[Dave Chinner <david@fromorbit.com>]

From: Dave Chinner <dchinner@redhat.com>

DAX does not do buffered IO (can't buffer direct access!) and hence
all read/write IO is vectored through the direct IO path.  Hence we
need to add the DAX IO path callouts to the direct IO
infrastructure.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
---
 fs/xfs/xfs_aops.c | 35 +++++++++++++++++++++++++++--------
 1 file changed, 27 insertions(+), 8 deletions(-)

diff --git a/fs/xfs/xfs_aops.c b/fs/xfs/xfs_aops.c
index 22cb03a..28b79c5 100644
--- a/fs/xfs/xfs_aops.c
+++ b/fs/xfs/xfs_aops.c
@@ -1558,6 +1558,30 @@ xfs_end_io_direct_write(
 	}
 }
 
+static inline ssize_t
+xfs_vm_do_dio(
+	struct inode		*inode,
+	int			rw,
+	struct kiocb		*iocb,
+	struct iov_iter		*iter,
+	loff_t			offset,
+	void			(*endio)(struct kiocb	*iocb,
+					 loff_t		offset,
+					 ssize_t	size,
+					 void		*private),
+	int			flags)
+{
+	struct block_device	*bdev;
+
+	if (IS_DAX(inode))
+		return dax_do_io(rw, iocb, inode, iter, offset,
+				 xfs_get_blocks_direct, endio, 0);
+
+	bdev = xfs_find_bdev_for_inode(inode);
+	return  __blockdev_direct_IO(rw, iocb, inode, bdev, iter, offset,
+				     xfs_get_blocks_direct, endio, NULL, flags);
+}
+
 STATIC ssize_t
 xfs_vm_direct_IO(
 	int			rw,
@@ -1566,17 +1590,12 @@ xfs_vm_direct_IO(
 	loff_t			offset)
 {
 	struct inode		*inode = iocb->ki_filp->f_mapping->host;
-	struct block_device	*bdev = xfs_find_bdev_for_inode(inode);
 
 	if (rw & WRITE) {
-		return __blockdev_direct_IO(rw, iocb, inode, bdev, iter,
-					    offset, xfs_get_blocks_direct,
-					    xfs_end_io_direct_write, NULL,
-					    DIO_ASYNC_EXTEND);
+		return xfs_vm_do_dio(inode, rw, iocb, iter, offset,
+				     xfs_end_io_direct_write, DIO_ASYNC_EXTEND);
 	}
-	return __blockdev_direct_IO(rw, iocb, inode, bdev, iter,
-				    offset, xfs_get_blocks_direct,
-				    NULL, NULL, 0);
+	return xfs_vm_do_dio(inode, rw, iocb, iter, offset, NULL, 0);
 }
 
 /*
-- 
2.0.0