On Mon 22-04-13 18:42:23, Jeff Moyer wrote:
> Jan, if I were to come up with a way of promoting a particular async
> queue to the front of the line, where would I put such a call in the
> ext4/jbd2 code to be effective?
As Ted wrote the simplies might be to put his directly in
__lock_buffer(). Something like:
diff --git a/fs/buffer.c b/fs/buffer.c
index b4dcb34..e026a3e 100644
--- a/fs/buffer.c
+++ b/fs/buffer.c
@@ -69,6 +69,12 @@ static int sleep_on_buffer(void *word)
void __lock_buffer(struct buffer_head *bh)
{
+ /*
+ * Likely under async writeback? Tell io scheduler we are
+ * now waiting for the IO...
+ */
+ if (PageWriteback(bh->b_page))
+ io_now_sync(bh->b_bdev, bh->b_blocknr);
wait_on_bit_lock(&bh->b_state, BH_Lock, sleep_on_buffer,
TASK_UNINTERRUPTIBLE);
}
Honza
--
Jan Kara <jack@xxxxxxx>
SUSE Labs, CR
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