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mm: Wait for writeback when grabbing pages to begin a write

When grabbing a page for a buffered IO write, the mm should wait for writeback
on the page to complete so that the page does not become writable during the IO
operation.  This change is needed to provide page stability during writes for
all filesystems.

Signed-off-by: Darrick J. Wong <djwong@us.ibm.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Darrick J. Wong преди 14 години
родител
ревизия
3d08bcc887
променени са 1 файла, в които са добавени 3 реда и са изтрити 1 реда
  1. 3 1
      mm/filemap.c

+ 3 - 1
mm/filemap.c

@@ -2327,7 +2327,7 @@ struct page *grab_cache_page_write_begin(struct address_space *mapping,
 repeat:
 	page = find_lock_page(mapping, index);
 	if (page)
-		return page;
+		goto found;
 
 	page = __page_cache_alloc(mapping_gfp_mask(mapping) & ~gfp_notmask);
 	if (!page)
@@ -2340,6 +2340,8 @@ repeat:
 			goto repeat;
 		return NULL;
 	}
+found:
+	wait_on_page_writeback(page);
 	return page;
 }
 EXPORT_SYMBOL(grab_cache_page_write_begin);