writeback: limit write_cache_pages integrity scanning to current EOF

[safe/jmp/linux-2.6] / mm / page-writeback.c

diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index b3dbb80..bbd396a 100644 (file)
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -851,7 +851,22 @@ int write_cache_pages(struct address_space *mapping,
                if (wbc->range_start == 0 && wbc->range_end == LLONG_MAX)
                        range_whole = 1;
                cycled = 1; /* ignore range_cyclic tests */
+
+               /*
+                * If this is a data integrity sync, cap the writeback to the
+                * current end of file. Any extension to the file that occurs
+                * after this is a new write and we don't need to write those
+                * pages out to fulfil our data integrity requirements. If we
+                * try to write them out, we can get stuck in this scan until
+                * the concurrent writer stops adding dirty pages and extending
+                * EOF.
+                */
+               if (wbc->sync_mode == WB_SYNC_ALL &&
+                   wbc->range_end == LLONG_MAX) {
+                       end = i_size_read(mapping->host) >> PAGE_CACHE_SHIFT;
+               }
        }
+
 retry:
        done_index = index;
        while (!done && (index <= end)) {