Merge branch 'master' into for-linus

1 files changed, 20 insertions, 10 deletions

diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index 5fa63bdf52e4..bbd396ac9546 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -835,7 +835,6 @@ int write_cache_pages(struct address_space *mapping,
         pgoff_t done_index;
         int cycled;
         int range_whole = 0;
-        long nr_to_write = wbc->nr_to_write;
 
         pagevec_init(&pvec, 0);
         if (wbc->range_cyclic) {
@@ -852,7 +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)) {
@@ -935,11 +949,10 @@ continue_unlock:
                                         done = 1;
                                         break;
                                 }
-                        }
+                        }
 
-                        if (nr_to_write > 0) {
-                                nr_to_write--;
-                                if (nr_to_write == 0 &&
+                        if (wbc->nr_to_write > 0) {
+                                if (--wbc->nr_to_write == 0 &&
                                     wbc->sync_mode == WB_SYNC_NONE) {
                                         /*
                                          * We stop writing back only if we are
@@ -970,11 +983,8 @@ continue_unlock:
                 end = writeback_index - 1;
                 goto retry;
         }
-        if (!wbc->no_nrwrite_index_update) {
-                if (wbc->range_cyclic || (range_whole && nr_to_write > 0))
-                        mapping->writeback_index = done_index;
-                wbc->nr_to_write = nr_to_write;
-        }
+        if (wbc->range_cyclic || (range_whole && wbc->nr_to_write > 0))
+                mapping->writeback_index = done_index;
 
         return ret;
 }