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>

diff --git a/fs/xfs/xfs_aops.c b/fs/xfs/xfs_aops.c
index 1d195e80d62e5f69c3c8ea0f143bcfaa3ac660b7..e5e9fc23f230b4225f5d8d48221ed8ab9a56aeb0 100644 (file)
--- 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);
 }
 
 /*