writeback: introduce writeback_control.inodes_written
The flusher works on dirty inodes in batches, and may quit prematurely
if the batch of inodes happen to be metadata-only dirtied: in this case
wbc->nr_to_write won't be decreased at all, which stands for "no pages
written" but also mis-interpreted as "no progress".
So introduce writeback_control.inodes_written to count the inodes get
cleaned from VFS POV. A non-zero value means there are some progress on
writeback, in which case more writeback can be tried.
Acked-by: Jan Kara <jack@suse.cz>
Acked-by: Mel Gorman <mel@csn.ul.ie>
Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
index fe190a8..e450429 100644
--- a/fs/fs-writeback.c
+++ b/fs/fs-writeback.c
@@ -464,6 +464,7 @@
* No need to add it back to the LRU.
*/
list_del_init(&inode->i_wb_list);
+ wbc->inodes_written++;
}
}
inode_sync_complete(inode);
@@ -725,6 +726,7 @@
wbc.more_io = 0;
wbc.nr_to_write = write_chunk;
wbc.pages_skipped = 0;
+ wbc.inodes_written = 0;
trace_wbc_writeback_start(&wbc, wb->bdi);
if (work->sb)
@@ -741,6 +743,8 @@
*/
if (wbc.nr_to_write <= 0)
continue;
+ if (wbc.inodes_written)
+ continue;
/*
* Didn't write everything and we don't have more IO, bail
*/