NTFS: Map the page instead of using page_address() before writing to it in

      fs/ntfs/aops.c::ntfs_mft_writepage().
Signed-off-by: Anton Altaparmakov <aia21@cantab.net>

fs/ntfs/ChangeLog

@@ -80,6 +80,8 @@ ToDo/Notes:
 	  the bug check from fs/ntfs/aops.c::ntfs_write_mst_block().  It is in
 	  fact required to write outside initialized size when preparing to
 	  extend the initialized size.
+	- Map the page instead of using page_address() before writing to it in
+	  fs/ntfs/aops.c::ntfs_mft_writepage().
 
 2.1.20 - Fix two stupid bugs introduced in 2.1.18 release.
 

fs/ntfs/aops.c

@@ -917,7 +917,7 @@ static int ntfs_write_mst_block(struct writeback_control *wbc,
 	if (!nr_bhs)
 		goto done;
 	/* Apply the mst protection fixups. */
-	kaddr = page_address(page);
+	kaddr = kmap(page);
 	for (i = 0; i < nr_bhs; i++) {
 		if (!(i % bhs_per_rec)) {
 			err = pre_write_mst_fixup((NTFS_RECORD*)(kaddr +
@@ -974,6 +974,7 @@ static int ntfs_write_mst_block(struct writeback_control *wbc,
 					bh_offset(bhs[i])));
 	}
 	flush_dcache_page(page);
+	kunmap(page);
 	if (unlikely(err)) {
 		/* I/O error during writing.  This is really bad! */
 		ntfs_error(vol->sb, "I/O error while writing ntfs record "
@@ -996,6 +997,7 @@ static int ntfs_write_mst_block(struct writeback_control *wbc,
 			post_write_mst_fixup((NTFS_RECORD*)(kaddr +
 					bh_offset(bhs[i])));
 	}
+	kunmap(page);
 cleanup_out:
 	/* Clean the buffers. */
 	for (i = 0; i < nr_bhs; i++)