vfs: improve writeback_inodes_wb()

Do not pin/unpin superblock for every inode in writeback_inodes_wb(), pin
it for the whole group of inodes which belong to the same superblock and
call writeback_sb_inodes() handler for them.

Signed-off-by: Edward Shishkin <edward.shishkin@gmail.com>
Cc: Jens Axboe <jens.axboe@oracle.com>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

1 files changed, 3 insertions, 0 deletions

diff --git a/include/linux/writeback.h b/include/linux/writeback.h
index 76e8903cd204..36520ded3e06 100644
--- a/include/linux/writeback.h
+++ b/include/linux/writeback.h
@@ -34,6 +34,9 @@ struct writeback_control {
         enum writeback_sync_modes sync_mode;
         unsigned long *older_than_this; /* If !NULL, only write back inodes
                                            older than this */
+        unsigned long wb_start;         /* Time writeback_inodes_wb was
+                                           called. This is needed to avoid
+                                           extra jobs and livelock */
         long nr_to_write;               /* Write this many pages, and decrement
                                            this for each page written */
         long pages_skipped;             /* Pages which were not written */