writeback: avoid extra sync work at enqueue time
This removes writeback_control.wb_start and does more straightforward
sync livelock prevention by setting .older_than_this to prevent extra
inodes from being enqueued in the first place.
Acked-by: Jan Kara <jack@suse.cz>
Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
index 565b1fd..d0553f3 100644
--- a/fs/fs-writeback.c
+++ b/fs/fs-writeback.c
@@ -544,15 +544,6 @@
continue;
}
- /*
- * Was this inode dirtied after sync_sb_inodes was called?
- * This keeps sync from extra jobs and livelock.
- */
- if (inode_dirtied_after(inode, wbc->wb_start)) {
- spin_unlock(&inode->i_lock);
- return 1;
- }
-
__iget(inode);
pages_skipped = wbc->pages_skipped;
@@ -585,9 +576,6 @@
{
int ret = 0;
- if (!wbc->wb_start)
- wbc->wb_start = jiffies; /* livelock avoidance */
-
while (!list_empty(&wb->b_io)) {
struct inode *inode = wb_inode(wb->b_io.prev);
struct super_block *sb = inode->i_sb;
@@ -686,7 +674,9 @@
if (wbc.sync_mode == WB_SYNC_ALL || wbc.tagged_writepages)
write_chunk = LONG_MAX;
- wbc.wb_start = jiffies; /* livelock avoidance */
+ oldest_jif = jiffies;
+ wbc.older_than_this = &oldest_jif;
+
spin_lock(&wb->list_lock);
for (;;) {
/*