sector_t                iblock,
        struct buffer_head      *bh_result,
        int                     create,
-       int                     direct)
+       bool                    direct)
 {
        struct xfs_inode        *ip = XFS_I(inode);
        struct xfs_mount        *mp = ip->i_mount;
                        if (error)
                                return error;
                        new = 1;
+
                } else {
                        /*
                         * Delalloc reservations do not require a transaction,
        struct buffer_head      *bh_result,
        int                     create)
 {
-       return __xfs_get_blocks(inode, iblock, bh_result, create, 0);
+       return __xfs_get_blocks(inode, iblock, bh_result, create, false);
 }
 
-STATIC int
+int
 xfs_get_blocks_direct(
        struct inode            *inode,
        sector_t                iblock,
        struct buffer_head      *bh_result,
        int                     create)
 {
-       return __xfs_get_blocks(inode, iblock, bh_result, create, 1);
+       return __xfs_get_blocks(inode, iblock, bh_result, create, true);
 }
 
-/*
- * Complete a direct I/O write request.
- *
- * The ioend structure is passed from __xfs_get_blocks() to tell us what to do.
- * If no ioend exists (i.e. @private == NULL) then the write IO is an overwrite
- * wholly within the EOF and so there is nothing for us to do. Note that in this
- * case the completion can be called in interrupt context, whereas if we have an
- * ioend we will always be called in task context (i.e. from a workqueue).
- */
-STATIC void
-xfs_end_io_direct_write(
-       struct kiocb            *iocb,
+static void
+__xfs_end_io_direct_write(
+       struct inode            *inode,
+       struct xfs_ioend        *ioend,
        loff_t                  offset,
-       ssize_t                 size,
-       void                    *private)
+       ssize_t                 size)
 {
-       struct inode            *inode = file_inode(iocb->ki_filp);
-       struct xfs_inode        *ip = XFS_I(inode);
-       struct xfs_mount        *mp = ip->i_mount;
-       struct xfs_ioend        *ioend = private;
+       struct xfs_mount        *mp = XFS_I(inode)->i_mount;
 
-       trace_xfs_gbmap_direct_endio(ip, offset, size,
-                                    ioend ? ioend->io_type : 0, NULL);
-
-       if (!ioend) {
-               ASSERT(offset + size <= i_size_read(inode));
-               return;
-       }
-
-       if (XFS_FORCED_SHUTDOWN(mp))
+       if (XFS_FORCED_SHUTDOWN(mp) || ioend->io_error)
                goto out_end_io;
 
        /*
         * here can result in EOF moving backwards and Bad Things Happen when
         * that occurs.
         */
-       spin_lock(&ip->i_flags_lock);
+       spin_lock(&XFS_I(inode)->i_flags_lock);
        if (offset + size > i_size_read(inode))
                i_size_write(inode, offset + size);
-       spin_unlock(&ip->i_flags_lock);
+       spin_unlock(&XFS_I(inode)->i_flags_lock);
 
        /*
         * If we are doing an append IO that needs to update the EOF on disk,
        return;
 }
 
+/*
+ * Complete a direct I/O write request.
+ *
+ * The ioend structure is passed from __xfs_get_blocks() to tell us what to do.
+ * If no ioend exists (i.e. @private == NULL) then the write IO is an overwrite
+ * wholly within the EOF and so there is nothing for us to do. Note that in this
+ * case the completion can be called in interrupt context, whereas if we have an
+ * ioend we will always be called in task context (i.e. from a workqueue).
+ */
+STATIC void
+xfs_end_io_direct_write(
+       struct kiocb            *iocb,
+       loff_t                  offset,
+       ssize_t                 size,
+       void                    *private)
+{
+       struct inode            *inode = file_inode(iocb->ki_filp);
+       struct xfs_ioend        *ioend = private;
+
+       trace_xfs_gbmap_direct_endio(XFS_I(inode), offset, size,
+                                    ioend ? ioend->io_type : 0, NULL);
+
+       if (!ioend) {
+               ASSERT(offset + size <= i_size_read(inode));
+               return;
+       }
+
+       __xfs_end_io_direct_write(inode, ioend, offset, size);
+}
+
+/*
+ * For DAX we need a mapping buffer callback for unwritten extent conversion
+ * when page faults allocate blocks and then zero them. Note that in this
+ * case the mapping indicated by the ioend may extend beyond EOF. We most
+ * definitely do not want to extend EOF here, so we trim back the ioend size to
+ * EOF.
+ */
+#ifdef CONFIG_FS_DAX
+void
+xfs_end_io_dax_write(
+       struct buffer_head      *bh,
+       int                     uptodate)
+{
+       struct xfs_ioend        *ioend = bh->b_private;
+       struct inode            *inode = ioend->io_inode;
+       ssize_t                 size = ioend->io_size;
+
+       ASSERT(IS_DAX(ioend->io_inode));
+
+       /* if there was an error zeroing, then don't convert it */
+       if (!uptodate)
+               ioend->io_error = -EIO;
+
+       /*
+        * Trim update to EOF, so we don't extend EOF during unwritten extent
+        * conversion of partial EOF blocks.
+        */
+       spin_lock(&XFS_I(inode)->i_flags_lock);
+       if (ioend->io_offset + size > i_size_read(inode))
+               size = i_size_read(inode) - ioend->io_offset;
+       spin_unlock(&XFS_I(inode)->i_flags_lock);
+
+       __xfs_end_io_direct_write(inode, ioend, ioend->io_offset, size);
+
+}
+#else
+void xfs_end_io_dax_write(struct buffer_head *bh, int uptodate) { }
+#endif
+
 STATIC ssize_t
 xfs_vm_direct_IO(
        struct kiocb            *iocb,
 
        if (file->f_mode & FMODE_NOCMTIME)
                ioflags |= XFS_IO_INVIS;
 
-       if (unlikely(ioflags & XFS_IO_ISDIRECT)) {
+       if ((ioflags & XFS_IO_ISDIRECT) && !IS_DAX(inode)) {
                xfs_buftarg_t   *target =
                        XFS_IS_REALTIME_INODE(ip) ?
                                mp->m_rtdev_targp : mp->m_ddev_targp;
 
        trace_xfs_file_splice_read(ip, count, *ppos, ioflags);
 
-       ret = generic_file_splice_read(infilp, ppos, pipe, count, flags);
+       /* for dax, we need to avoid the page cache */
+       if (IS_DAX(VFS_I(ip)))
+               ret = default_file_splice_read(infilp, ppos, pipe, count, flags);
+       else
+               ret = generic_file_splice_read(infilp, ppos, pipe, count, flags);
        if (ret > 0)
                XFS_STATS_ADD(xs_read_bytes, ret);
 
                                        mp->m_rtdev_targp : mp->m_ddev_targp;
 
        /* DIO must be aligned to device logical sector size */
-       if ((pos | count) & target->bt_logical_sectormask)
+       if (!IS_DAX(inode) && ((pos | count) & target->bt_logical_sectormask))
                return -EINVAL;
 
        /* "unaligned" here means not aligned to a filesystem block */
 out:
        xfs_rw_iunlock(ip, iolock);
 
-       /* No fallback to buffered IO on errors for XFS. */
-       ASSERT(ret < 0 || ret == count);
+       /*
+        * No fallback to buffered IO on errors for XFS. DAX can result in
+        * partial writes, but direct IO will either complete fully or fail.
+        */
+       ASSERT(ret < 0 || ret == count || IS_DAX(VFS_I(ip)));
        return ret;
 }
 
        if (XFS_FORCED_SHUTDOWN(ip->i_mount))
                return -EIO;
 
-       if (unlikely(iocb->ki_flags & IOCB_DIRECT))
+       if ((iocb->ki_flags & IOCB_DIRECT) || IS_DAX(inode))
                ret = xfs_file_dio_aio_write(iocb, from);
        else
                ret = xfs_file_buffered_aio_write(iocb, from);
        return xfs_readdir(ip, ctx, bufsize);
 }
 
-STATIC int
-xfs_file_mmap(
-       struct file     *filp,
-       struct vm_area_struct *vma)
-{
-       vma->vm_ops = &xfs_file_vm_ops;
-
-       file_accessed(filp);
-       return 0;
-}
-
 /*
  * This type is designed to indicate the type of offset we would like
  * to search from page cache for xfs_seek_hole_data().
  * ordering of:
  *
  * mmap_sem (MM)
- *   i_mmap_lock (XFS - truncate serialisation)
- *     page_lock (MM)
- *       i_lock (XFS - extent map serialisation)
+ *   sb_start_pagefault(vfs, freeze)
+ *     i_mmap_lock (XFS - truncate serialisation)
+ *       page_lock (MM)
+ *         i_lock (XFS - extent map serialisation)
  */
-STATIC int
-xfs_filemap_fault(
-       struct vm_area_struct   *vma,
-       struct vm_fault         *vmf)
-{
-       struct xfs_inode        *ip = XFS_I(vma->vm_file->f_mapping->host);
-       int                     error;
-
-       trace_xfs_filemap_fault(ip);
-
-       xfs_ilock(ip, XFS_MMAPLOCK_SHARED);
-       error = filemap_fault(vma, vmf);
-       xfs_iunlock(ip, XFS_MMAPLOCK_SHARED);
-
-       return error;
-}
 
 /*
  * mmap()d file has taken write protection fault and is being made writable. We
        struct vm_area_struct   *vma,
        struct vm_fault         *vmf)
 {
-       struct xfs_inode        *ip = XFS_I(vma->vm_file->f_mapping->host);
+       struct inode            *inode = file_inode(vma->vm_file);
        int                     ret;
 
-       trace_xfs_filemap_page_mkwrite(ip);
+       trace_xfs_filemap_page_mkwrite(XFS_I(inode));
 
-       sb_start_pagefault(VFS_I(ip)->i_sb);
+       sb_start_pagefault(inode->i_sb);
        file_update_time(vma->vm_file);
-       xfs_ilock(ip, XFS_MMAPLOCK_SHARED);
+       xfs_ilock(XFS_I(inode), XFS_MMAPLOCK_SHARED);
+
+       if (IS_DAX(inode)) {
+               ret = __dax_mkwrite(vma, vmf, xfs_get_blocks_direct,
+                                   xfs_end_io_dax_write);
+       } else {
+               ret = __block_page_mkwrite(vma, vmf, xfs_get_blocks);
+               ret = block_page_mkwrite_return(ret);
+       }
+
+       xfs_iunlock(XFS_I(inode), XFS_MMAPLOCK_SHARED);
+       sb_end_pagefault(inode->i_sb);
+
+       return ret;
+}
+
+STATIC int
+xfs_filemap_fault(
+       struct vm_area_struct   *vma,
+       struct vm_fault         *vmf)
+{
+       struct xfs_inode        *ip = XFS_I(file_inode(vma->vm_file));
+       int                     ret;
 
-       ret = __block_page_mkwrite(vma, vmf, xfs_get_blocks);
+       trace_xfs_filemap_fault(ip);
+
+       /* DAX can shortcut the normal fault path on write faults! */
+       if ((vmf->flags & FAULT_FLAG_WRITE) && IS_DAX(VFS_I(ip)))
+               return xfs_filemap_page_mkwrite(vma, vmf);
 
+       xfs_ilock(ip, XFS_MMAPLOCK_SHARED);
+       ret = filemap_fault(vma, vmf);
        xfs_iunlock(ip, XFS_MMAPLOCK_SHARED);
-       sb_end_pagefault(VFS_I(ip)->i_sb);
 
-       return block_page_mkwrite_return(ret);
+       return ret;
+}
+
+static const struct vm_operations_struct xfs_file_vm_ops = {
+       .fault          = xfs_filemap_fault,
+       .map_pages      = filemap_map_pages,
+       .page_mkwrite   = xfs_filemap_page_mkwrite,
+};
+
+STATIC int
+xfs_file_mmap(
+       struct file     *filp,
+       struct vm_area_struct *vma)
+{
+       file_accessed(filp);
+       vma->vm_ops = &xfs_file_vm_ops;
+       if (IS_DAX(file_inode(filp)))
+               vma->vm_flags |= VM_MIXEDMAP;
+       return 0;
 }
 
 const struct file_operations xfs_file_operations = {
 #endif
        .fsync          = xfs_dir_fsync,
 };
-
-static const struct vm_operations_struct xfs_file_vm_ops = {
-       .fault          = xfs_filemap_fault,
-       .map_pages      = filemap_map_pages,
-       .page_mkwrite   = xfs_filemap_page_mkwrite,
-};