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authorShaohua Li <shli@fb.com>2015-05-08 10:51:28 -0700
committerJens Axboe <axboe@fb.com>2015-05-08 14:17:14 -0600
commitdd6cf3e18decb4895503db1752bb5500c4dd588d (patch)
tree14caffdac252bbebf68678b808e22ca13f7a3302 /block
parent9dc6c806b3c4812619e305685b3c86835bf784ab (diff)
blk: clean up plug
Current code looks like inner plug gets flushed with a blk_finish_plug(). Actually it's a nop. All requests/callbacks are added to current->plug, while only outmost plug is assigned to current->plug. So inner plug always has empty request/callback list, which makes blk_flush_plug_list() a nop. This tries to make the code more clear. Signed-off-by: Shaohua Li <shli@fb.com> Reviewed-by: Jeff Moyer <jmoyer@redhat.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@fb.com>
Diffstat (limited to 'block')
-rw-r--r--block/blk-core.c24
1 files changed, 12 insertions, 12 deletions
diff --git a/block/blk-core.c b/block/blk-core.c
index 2e5020f37d55..9dcfb8ec554b 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -3032,21 +3032,20 @@ void blk_start_plug(struct blk_plug *plug)
{
struct task_struct *tsk = current;
+ /*
+ * If this is a nested plug, don't actually assign it.
+ */
+ if (tsk->plug)
+ return;
+
INIT_LIST_HEAD(&plug->list);
INIT_LIST_HEAD(&plug->mq_list);
INIT_LIST_HEAD(&plug->cb_list);
-
/*
- * If this is a nested plug, don't actually assign it. It will be
- * flushed on its own.
+ * Store ordering should not be needed here, since a potential
+ * preempt will imply a full memory barrier
*/
- if (!tsk->plug) {
- /*
- * Store ordering should not be needed here, since a potential
- * preempt will imply a full memory barrier
- */
- tsk->plug = plug;
- }
+ tsk->plug = plug;
}
EXPORT_SYMBOL(blk_start_plug);
@@ -3193,10 +3192,11 @@ void blk_flush_plug_list(struct blk_plug *plug, bool from_schedule)
void blk_finish_plug(struct blk_plug *plug)
{
+ if (plug != current->plug)
+ return;
blk_flush_plug_list(plug, false);
- if (plug == current->plug)
- current->plug = NULL;
+ current->plug = NULL;
}
EXPORT_SYMBOL(blk_finish_plug);