xfs: don't allow highmem pages in xfile mappings

XFS is generally used on 64-bit, non-highmem platforms and xfile
mappings are accessed all the time.  Reduce our pain by not allowing
any highmem mappings in the xfile page cache and remove all the kmap
calls for it.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: "Darrick J. Wong" <djwong@kernel.org>
Signed-off-by: Chandan Babu R <chandanbabu@kernel.org>

fs/xfs/scrub/xfarray.c

@@ -580,7 +580,7 @@ xfarray_sort_get_page(
 	 * xfile pages must never be mapped into userspace, so we skip the
 	 * dcache flush when mapping the page.
 	 */
-	si->page_kaddr = kmap_local_page(si->xfpage.page);
+	si->page_kaddr = page_address(si->xfpage.page);
 	return 0;
 }
 
@@ -592,7 +592,6 @@ xfarray_sort_put_page(
 	if (!si->page_kaddr)
 		return 0;
 
-	kunmap_local(si->page_kaddr);
 	si->page_kaddr = NULL;
 
 	return xfile_put_page(si->array->xfile, &si->xfpage);

fs/xfs/scrub/xfile.c

@@ -77,6 +77,12 @@ xfile_create(
 	inode = file_inode(xf->file);
 	lockdep_set_class(&inode->i_rwsem, &xfile_i_mutex_key);
 
+	/*
+	 * We don't want to bother with kmapping data during repair, so don't
+	 * allow highmem pages to back this mapping.
+	 */
+	mapping_set_gfp_mask(inode->i_mapping, GFP_KERNEL);
+
 	trace_xfile_create(xf);
 
 	*xfilep = xf;
@@ -126,7 +132,6 @@ xfile_load(
 
 	pflags = memalloc_nofs_save();
 	while (count > 0) {
-		void		*p, *kaddr;
 		unsigned int	len;
 
 		len = min_t(ssize_t, count, PAGE_SIZE - offset_in_page(pos));
@@ -153,10 +158,7 @@ xfile_load(
 		 * xfile pages must never be mapped into userspace, so
 		 * we skip the dcache flush.
 		 */
-		kaddr = kmap_local_page(page);
-		p = kaddr + offset_in_page(pos);
-		memcpy(buf, p, len);
-		kunmap_local(kaddr);
+		memcpy(buf, page_address(page) + offset_in_page(pos), len);
 		put_page(page);
 
 advance:
@@ -221,14 +223,13 @@ xfile_store(
 		 * the dcache flush.  If the page is not uptodate, zero it
 		 * before writing data.
 		 */
-		kaddr = kmap_local_page(page);
+		kaddr = page_address(page);
 		if (!PageUptodate(page)) {
 			memset(kaddr, 0, PAGE_SIZE);
 			SetPageUptodate(page);
 		}
 		p = kaddr + offset_in_page(pos);
 		memcpy(p, buf, len);
-		kunmap_local(kaddr);
 
 		ret = aops->write_end(NULL, mapping, pos, len, len, page,
 				fsdata);
@@ -314,11 +315,7 @@ xfile_get_page(
 	 * to the caller and make sure the backing store will hold on to them.
 	 */
 	if (!PageUptodate(page)) {
-		void	*kaddr;
-
-		kaddr = kmap_local_page(page);
-		memset(kaddr, 0, PAGE_SIZE);
-		kunmap_local(kaddr);
+		memset(page_address(page), 0, PAGE_SIZE);
 		SetPageUptodate(page);
 	}