xfs: huge page fault support

Use DAX to provide support for huge pages.
Signed-off-by: Matthew Wilcox <willy@linux.intel.com>
Cc: Hillf Danton <dhillf@gmail.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: Jan Kara <jack@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fs/xfs/xfs_file.c

@@ -1546,8 +1546,36 @@ xfs_filemap_fault(
 	return ret;
 }
 
+STATIC int
+xfs_filemap_pmd_fault(
+	struct vm_area_struct	*vma,
+	unsigned long		addr,
+	pmd_t			*pmd,
+	unsigned int		flags)
+{
+	struct inode		*inode = file_inode(vma->vm_file);
+	struct xfs_inode	*ip = XFS_I(inode);
+	int			ret;
+
+	if (!IS_DAX(inode))
+		return VM_FAULT_FALLBACK;
+
+	trace_xfs_filemap_pmd_fault(ip);
+
+	sb_start_pagefault(inode->i_sb);
+	file_update_time(vma->vm_file);
+	xfs_ilock(XFS_I(inode), XFS_MMAPLOCK_SHARED);
+	ret = __dax_pmd_fault(vma, addr, pmd, flags, xfs_get_blocks_direct,
+				    xfs_end_io_dax_write);
+	xfs_iunlock(XFS_I(inode), XFS_MMAPLOCK_SHARED);
+	sb_end_pagefault(inode->i_sb);
+
+	return ret;
+}
+
 static const struct vm_operations_struct xfs_file_vm_ops = {
 	.fault		= xfs_filemap_fault,
+	.pmd_fault	= xfs_filemap_pmd_fault,
 	.map_pages	= filemap_map_pages,
 	.page_mkwrite	= xfs_filemap_page_mkwrite,
 };
@@ -1560,7 +1588,7 @@ xfs_file_mmap(
 	file_accessed(filp);
 	vma->vm_ops = &xfs_file_vm_ops;
 	if (IS_DAX(file_inode(filp)))
-		vma->vm_flags |= VM_MIXEDMAP;
+		vma->vm_flags |= VM_MIXEDMAP | VM_HUGEPAGE;
 	return 0;
 }
 

fs/xfs/xfs_trace.h

@@ -687,6 +687,7 @@ DEFINE_INODE_EVENT(xfs_inode_clear_eofblocks_tag);
 DEFINE_INODE_EVENT(xfs_inode_free_eofblocks_invalid);
 
 DEFINE_INODE_EVENT(xfs_filemap_fault);
+DEFINE_INODE_EVENT(xfs_filemap_pmd_fault);
 DEFINE_INODE_EVENT(xfs_filemap_page_mkwrite);
 
 DECLARE_EVENT_CLASS(xfs_iref_class,