1 files changed, 22 insertions, 4 deletions

diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
index f81f9e71871e..eed480639902 100644
--- a/fs/fs-writeback.c
+++ b/fs/fs-writeback.c
@@ -196,7 +196,7 @@ static void redirty_tail(struct inode *inode)
                 struct inode *tail_inode;
 
                 tail_inode = list_entry(sb->s_dirty.next, struct inode, i_list);
-                if (!time_after_eq(inode->dirtied_when,
+                if (time_before(inode->dirtied_when,
                                 tail_inode->dirtied_when))
                         inode->dirtied_when = jiffies;
         }
@@ -220,6 +220,21 @@ static void inode_sync_complete(struct inode *inode)
         wake_up_bit(&inode->i_state, __I_SYNC);
 }
 
+static bool inode_dirtied_after(struct inode *inode, unsigned long t)
+{
+        bool ret = time_after(inode->dirtied_when, t);
+#ifndef CONFIG_64BIT
+        /*
+         * For inodes being constantly redirtied, dirtied_when can get stuck.
+         * It _appears_ to be in the future, but is actually in distant past.
+         * This test is necessary to prevent such wrapped-around relative times
+         * from permanently stopping the whole pdflush writeback.
+         */
+        ret = ret && time_before_eq(inode->dirtied_when, jiffies);
+#endif
+        return ret;
+}
+
 /*
  * Move expired dirty inodes from @delaying_queue to @dispatch_queue.
  */
@@ -231,7 +246,7 @@ static void move_expired_inodes(struct list_head *delaying_queue,
                 struct inode *inode = list_entry(delaying_queue->prev,
                                                 struct inode, i_list);
                 if (older_than_this &&
-                        time_after(inode->dirtied_when, *older_than_this))
+                    inode_dirtied_after(inode, *older_than_this))
                         break;
                 list_move(&inode->i_list, dispatch_queue);
         }
@@ -492,8 +507,11 @@ void generic_sync_sb_inodes(struct super_block *sb,
                         continue;               /* blockdev has wrong queue */
                 }
 
-                /* Was this inode dirtied after sync_sb_inodes was called? */
-                if (time_after(inode->dirtied_when, start))
+                /*
+                 * Was this inode dirtied after sync_sb_inodes was called?
+                 * This keeps sync from extra jobs and livelock.
+                 */
+                if (inode_dirtied_after(inode, start))
                         break;
 
                 /* Is another pdflush already flushing this queue? */