writeback: improve readability of the wb_writeback() continue/break logic

And throw some comments in there, too.

Reviewed-by: Wu Fengguang <fengguang.wu@intel.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

1 files changed, 23 insertions, 20 deletions

diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
index 916e83489caa..15e375bf93e6 100644
--- a/fs/fs-writeback.c
+++ b/fs/fs-writeback.c
@@ -750,29 +750,32 @@ static long wb_writeback(struct bdi_writeback *wb,
                 wrote += MAX_WRITEBACK_PAGES - wbc.nr_to_write;
 
                 /*
-                 * If we ran out of stuff to write, bail unless more_io got set
+                 * If we consumed everything, see if we have more
                  */
-                if (wbc.nr_to_write > 0) {
-                        if (wbc.more_io) {
-                                if (wbc.nr_to_write < MAX_WRITEBACK_PAGES)
-                                        continue;
-                                /*
-                                 * Nothing written. Wait for some inode to
-                                 * become available for writeback. Otherwise
-                                 * we'll just busyloop.
-                                 */
-                                spin_lock(&inode_lock);
-                                if (!list_empty(&wb->b_more_io))  {
-                                        inode = list_entry(
-                                                        wb->b_more_io.prev,
-                                                        struct inode, i_list);
-                                        inode_wait_for_writeback(inode);
-                                }
-                                spin_unlock(&inode_lock);
-                                continue;
-                        }
+                if (wbc.nr_to_write <= 0)
+                        continue;
+                /*
+                 * Didn't write everything and we don't have more IO, bail
+                 */
+                if (!wbc.more_io)
                         break;
+                /*
+                 * Did we write something? Try for more
+                 */
+                if (wbc.nr_to_write < MAX_WRITEBACK_PAGES)
+                        continue;
+                /*
+                 * Nothing written. Wait for some inode to
+                 * become available for writeback. Otherwise
+                 * we'll just busyloop.
+                 */
+                spin_lock(&inode_lock);
+                if (!list_empty(&wb->b_more_io))  {
+                        inode = list_entry(wb->b_more_io.prev,
+                                                struct inode, i_list);
+                        inode_wait_for_writeback(inode);
                 }
+                spin_unlock(&inode_lock);
         }
 
         return wrote;