block: kill off REQ_UNPLUG

With the plugging now being explicitly controlled by the
submitter, callers need not pass down unplugging hints
to the block layer. If they want to unplug, it's because they
manually plugged on their own - in which case, they should just
unplug at will.

Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
diff --git a/fs/jbd2/commit.c b/fs/jbd2/commit.c
index f3ad159..3da1cc4 100644
--- a/fs/jbd2/commit.c
+++ b/fs/jbd2/commit.c
@@ -137,9 +137,9 @@
 	if (journal->j_flags & JBD2_BARRIER &&
 	    !JBD2_HAS_INCOMPAT_FEATURE(journal,
 				       JBD2_FEATURE_INCOMPAT_ASYNC_COMMIT))
-		ret = submit_bh(WRITE_SYNC_PLUG | WRITE_FLUSH_FUA, bh);
+		ret = submit_bh(WRITE_SYNC | WRITE_FLUSH_FUA, bh);
 	else
-		ret = submit_bh(WRITE_SYNC_PLUG, bh);
+		ret = submit_bh(WRITE_SYNC, bh);
 
 	*cbh = bh;
 	return ret;
@@ -369,7 +369,7 @@
 	 * instead we rely on sync_buffer() doing the unplug for us.
 	 */
 	if (commit_transaction->t_synchronous_commit)
-		write_op = WRITE_SYNC_PLUG;
+		write_op = WRITE_SYNC;
 	trace_jbd2_commit_locking(journal, commit_transaction);
 	stats.run.rs_wait = commit_transaction->t_max_wait;
 	stats.run.rs_locked = jiffies;