3 files changed, 41 insertions, 27 deletions

diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index b289310e2c89..bbd396ac9546 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -597,7 +597,7 @@ static void balance_dirty_pages(struct address_space *mapping,
             (!laptop_mode && ((global_page_state(NR_FILE_DIRTY)
                                + global_page_state(NR_UNSTABLE_NFS))
                                           > background_thresh)))
-                bdi_start_writeback(bdi, NULL, 0, 0);
+                bdi_start_writeback(bdi, NULL, 0);
 }
 
 void set_page_dirty_balance(struct page *page, int page_mkwrite)
@@ -707,7 +707,7 @@ void laptop_mode_timer_fn(unsigned long data)
          */
 
         if (bdi_has_dirty_io(&q->backing_dev_info))
-                bdi_start_writeback(&q->backing_dev_info, NULL, nr_pages, 0);
+                bdi_start_writeback(&q->backing_dev_info, NULL, nr_pages);
 }
 
 /*
@@ -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;
 }
diff --git a/mm/shmem.c b/mm/shmem.c
index 7e5030ae18ff..f65f84062db5 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -764,10 +764,11 @@ done2:
 static int shmem_notify_change(struct dentry *dentry, struct iattr *attr)
 {
         struct inode *inode = dentry->d_inode;
+        loff_t newsize = attr->ia_size;
         int error;
 
-        if (S_ISREG(inode->i_mode) && (attr->ia_valid & ATTR_SIZE)) {
-                loff_t newsize = attr->ia_size;
+        if (S_ISREG(inode->i_mode) && (attr->ia_valid & ATTR_SIZE)
+                                        && newsize != inode->i_size) {
                 struct page *page = NULL;
 
                 if (newsize < inode->i_size) {
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 915dceb487c1..9c7e57cc63a3 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -1724,13 +1724,13 @@ static void shrink_zone(int priority, struct zone *zone,
  * If a zone is deemed to be full of pinned pages then just give it a light
  * scan then give up on it.
  */
-static int shrink_zones(int priority, struct zonelist *zonelist,
+static bool shrink_zones(int priority, struct zonelist *zonelist,
                                         struct scan_control *sc)
 {
         enum zone_type high_zoneidx = gfp_zone(sc->gfp_mask);
         struct zoneref *z;
         struct zone *zone;
-        int progress = 0;
+        bool all_unreclaimable = true;
 
         for_each_zone_zonelist_nodemask(zone, z, zonelist, high_zoneidx,
                                         sc->nodemask) {
@@ -1757,9 +1757,9 @@ static int shrink_zones(int priority, struct zonelist *zonelist,
                 }
 
                 shrink_zone(priority, zone, sc);
-                progress = 1;
+                all_unreclaimable = false;
         }
-        return progress;
+        return all_unreclaimable;
 }
 
 /*
@@ -1782,7 +1782,7 @@ static unsigned long do_try_to_free_pages(struct zonelist *zonelist,
                                         struct scan_control *sc)
 {
         int priority;
-        unsigned long ret = 0;
+        bool all_unreclaimable;
         unsigned long total_scanned = 0;
         struct reclaim_state *reclaim_state = current->reclaim_state;
         unsigned long lru_pages = 0;
@@ -1813,7 +1813,7 @@ static unsigned long do_try_to_free_pages(struct zonelist *zonelist,
                 sc->nr_scanned = 0;
                 if (!priority)
                         disable_swap_token();
-                ret = shrink_zones(priority, zonelist, sc);
+                all_unreclaimable = shrink_zones(priority, zonelist, sc);
                 /*
                  * Don't shrink slabs when reclaiming memory from
                  * over limit cgroups
@@ -1826,10 +1826,8 @@ static unsigned long do_try_to_free_pages(struct zonelist *zonelist,
                         }
                 }
                 total_scanned += sc->nr_scanned;
-                if (sc->nr_reclaimed >= sc->nr_to_reclaim) {
-                        ret = sc->nr_reclaimed;
+                if (sc->nr_reclaimed >= sc->nr_to_reclaim)
                         goto out;
-                }
 
                 /*
                  * Try to write back as many pages as we just scanned.  This
@@ -1849,9 +1847,7 @@ static unsigned long do_try_to_free_pages(struct zonelist *zonelist,
                     priority < DEF_PRIORITY - 2)
                         congestion_wait(BLK_RW_ASYNC, HZ/10);
         }
-        /* top priority shrink_zones still had more to do? don't OOM, then */
-        if (ret && scanning_global_lru(sc))
-                ret = sc->nr_reclaimed;
+
 out:
         /*
          * Now that we've scanned all the zones at this priority level, note
@@ -1877,7 +1873,14 @@ out:
         delayacct_freepages_end();
         put_mems_allowed();
 
-        return ret;
+        if (sc->nr_reclaimed)
+                return sc->nr_reclaimed;
+
+        /* top priority shrink_zones still had more to do? don't OOM, then */
+        if (scanning_global_lru(sc) && !all_unreclaimable)
+                return 1;
+
+        return 0;
 }
 
 unsigned long try_to_free_pages(struct zonelist *zonelist, int order,