block: Remove should_sort judgement when flush blk_plug

In commit 975927b942c932,it add blk_rq_pos to sort rq when flushing.
Although this commit was used for the situation which blk_plug handled
multi devices on the same time like md device.
I think there must be some situations like this but only single
device.
So remove the should_sort judgement.
Because the parameter should_sort is only for this purpose,it can delete
should_sort from blk_plug.

CC: Shaohua Li <shli@kernel.org>
Signed-off-by: Jianpeng Ma <majianpeng@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/block/blk-core.c b/block/blk-core.c
index c973249d68cda01e0c7889ae8708e4da0f9ca4d2..aca5d82ff13c2fed7efa872a9d14d0077ad4374f 100644 (file)
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -1548,13 +1548,6 @@ get_rq:
                if (list_empty(&plug->list))
                        trace_block_plug(q);
                else {
-                       if (!plug->should_sort) {
-                               struct request *__rq;
-
-                               __rq = list_entry_rq(plug->list.prev);
-                               if (__rq->q != q)
-                                       plug->should_sort = 1;
-                       }
                        if (request_count >= BLK_MAX_REQUEST_COUNT) {
                                blk_flush_plug_list(plug, false);
                                trace_block_plug(q);
@@ -2888,7 +2881,6 @@ void blk_start_plug(struct blk_plug *plug)
        plug->magic = PLUG_MAGIC;
        INIT_LIST_HEAD(&plug->list);
        INIT_LIST_HEAD(&plug->cb_list);
-       plug->should_sort = 0;
 
        /*
         * If this is a nested plug, don't actually assign it. It will be
@@ -2990,10 +2982,7 @@ void blk_flush_plug_list(struct blk_plug *plug, bool from_schedule)
 
        list_splice_init(&plug->list, &list);
 
-       if (plug->should_sort) {
-               list_sort(NULL, &list, plug_rq_cmp);
-               plug->should_sort = 0;
-       }
+       list_sort(NULL, &list, plug_rq_cmp);
 
        q = NULL;
        depth = 0;

diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index f94bc83011ed5c7a3c96f0adabefa1246f86cb47..dbe74279f3d6f920ffb226ef71aa4ffb41845cab 100644 (file)
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -974,7 +974,6 @@ struct blk_plug {
        unsigned long magic; /* detect uninitialized use-cases */
        struct list_head list; /* requests */
        struct list_head cb_list; /* md requires an unplug callback */
-       unsigned int should_sort; /* list to be sorted before flushing? */
 };
 #define BLK_MAX_REQUEST_COUNT 16