1 files changed, 17 insertions, 5 deletions

diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index b493db7841dc..3c84128596ba 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -209,7 +209,7 @@ int dirty_bytes_handler(struct ctl_table *table, int write,
                 struct file *filp, void __user *buffer, size_t *lenp,
                 loff_t *ppos)
 {
-        int old_bytes = vm_dirty_bytes;
+        unsigned long old_bytes = vm_dirty_bytes;
         int ret;
 
         ret = proc_doulongvec_minmax(table, write, filp, buffer, lenp, ppos);
@@ -1051,13 +1051,25 @@ continue_unlock:
                                 }
                         }
 
-                        if (wbc->sync_mode == WB_SYNC_NONE) {
-                                wbc->nr_to_write--;
-                                if (wbc->nr_to_write <= 0) {
+                        if (nr_to_write > 0) {
+                                nr_to_write--;
+                                if (nr_to_write == 0 &&
+                                    wbc->sync_mode == WB_SYNC_NONE) {
+                                        /*
+                                         * We stop writing back only if we are
+                                         * not doing integrity sync. In case of
+                                         * integrity sync we have to keep going
+                                         * because someone may be concurrently
+                                         * dirtying pages, and we might have
+                                         * synced a lot of newly appeared dirty
+                                         * pages, but have not synced all of the
+                                         * old dirty pages.
+                                         */
                                         done = 1;
                                         break;
                                 }
                         }
+
                         if (wbc->nonblocking && bdi_write_congested(bdi)) {
                                 wbc->encountered_congestion = 1;
                                 done = 1;
@@ -1067,7 +1079,7 @@ continue_unlock:
                 pagevec_release(&pvec);
                 cond_resched();
         }
-        if (!cycled) {
+        if (!cycled && !done) {
                 /*
                  * range_cyclic:
                  * We hit the last page and there is more work to be done: wrap