NFS: Don't use page_file_mapping after removing the page

bcodding-rh · amschuma-ntap · commit d2ceb7e57086 · 2019-02-12T15:56:28.000-05:00
If nfs_page_async_flush() removes the page from the mapping, then we can't use page_file_mapping() on it as nfs_updatepate() is wont to do when receiving an error. Instead, push the mapping to the stack before the page is possibly truncated. Fixes: 8fc75be ("NFS: Fix up return value on fatal errors in nfs_page_async_flush()") Signed-off-by: Benjamin Coddington <bcodding@redhat.com> Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
diff --git a/fs/nfs/write.c b/fs/nfs/write.c
@@ -238,9 +238,9 @@ static void nfs_grow_file(struct page *page, unsigned int offset, unsigned int c
 }
 
 /* A writeback failed: mark the page as bad, and invalidate the page cache */
-static void nfs_set_pageerror(struct page *page)
+static void nfs_set_pageerror(struct address_space *mapping)
 {
-	nfs_zap_mapping(page_file_mapping(page)->host, page_file_mapping(page));
+	nfs_zap_mapping(mapping->host, mapping);
 }
 
 /*
@@ -994,7 +994,7 @@ static void nfs_write_completion(struct nfs_pgio_header *hdr)
 		nfs_list_remove_request(req);
 		if (test_bit(NFS_IOHDR_ERROR, &hdr->flags) &&
 		    (hdr->good_bytes < bytes)) {
-			nfs_set_pageerror(req->wb_page);
+			nfs_set_pageerror(page_file_mapping(req->wb_page));
 			nfs_context_set_write_error(req->wb_context, hdr->error);
 			goto remove_req;
 		}
@@ -1348,7 +1348,8 @@ int nfs_updatepage(struct file *file, struct page *page,
 		unsigned int offset, unsigned int count)
 {
 	struct nfs_open_context *ctx = nfs_file_open_context(file);
-	struct inode	*inode = page_file_mapping(page)->host;
+	struct address_space *mapping = page_file_mapping(page);
+	struct inode	*inode = mapping->host;
 	int		status = 0;
 
 	nfs_inc_stats(inode, NFSIOS_VFSUPDATEPAGE);
@@ -1366,7 +1367,7 @@ int nfs_updatepage(struct file *file, struct page *page,
 
 	status = nfs_writepage_setup(ctx, page, offset, count);
 	if (status < 0)
-		nfs_set_pageerror(page);
+		nfs_set_pageerror(mapping);
 	else
 		__set_page_dirty_nobuffers(page);
 out:
