xfs: add DAX IO path support

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>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>

1 files changed, 27 insertions, 9 deletions

diff --git a/fs/xfs/xfs_aops.c b/fs/xfs/xfs_aops.c
index 1d195e80d62e..e5e9fc23f230 100644
--- a/fs/xfs/xfs_aops.c
+++ b/fs/xfs/xfs_aops.c
@@ -1657,6 +1657,29 @@ xfs_end_io_dax_write(
 void xfs_end_io_dax_write(struct buffer_head *bh, int uptodate) { }
 #endif
 
+static inline ssize_t
+xfs_vm_do_dio(
+        struct inode            *inode,
+        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(iocb, inode, iter, offset,
+                                 xfs_get_blocks_direct, endio, 0);
+
+        bdev = xfs_find_bdev_for_inode(inode);
+        return  __blockdev_direct_IO(iocb, inode, bdev, iter, offset,
+                                     xfs_get_blocks_direct, endio, NULL, flags);
+}
+
 STATIC ssize_t
 xfs_vm_direct_IO(
         struct kiocb            *iocb,
@@ -1664,16 +1687,11 @@ 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 (iov_iter_rw(iter) == WRITE) {
-                return __blockdev_direct_IO(iocb, inode, bdev, iter, offset,
-                                            xfs_get_blocks_direct,
-                                            xfs_end_io_direct_write, NULL,
-                                            DIO_ASYNC_EXTEND);
-        }
-        return __blockdev_direct_IO(iocb, inode, bdev, iter, offset,
-                                    xfs_get_blocks_direct, NULL, NULL, 0);
+        if (iov_iter_rw(iter) == WRITE)
+                return xfs_vm_do_dio(inode, iocb, iter, offset,
+                                     xfs_end_io_direct_write, DIO_ASYNC_EXTEND);
+        return xfs_vm_do_dio(inode, iocb, iter, offset, NULL, 0);
 }
 
 /*