From 4e67694c0da41170dc50357c76034500c8c8f50a Mon Sep 17 00:00:00 2001
From: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Date: Thu, 14 Apr 2011 17:58:19 -0400
Subject: [PATCH] xen/blkback: remove per-queue plugging
commit c69163c6522d2017cc7e3fe5d23f64bc78f2870c ("block: remove per-queue plugging")
added two new interfaces to plug and unplug: blk_start_plug
and blk_finish_plug. Lets use those.
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
---
drivers/xen/blkback/blkback.c | 44 +++++++----------------------------
drivers/xen/blkback/common.h | 1 -
2 files changed, 9 insertions(+), 36 deletions(-)
diff --git a/drivers/xen/blkback/blkback.c b/drivers/xen/blkback/blkback.c
index 2d413930f235d..464f2e0b5a61a 100644
--- a/drivers/xen/blkback/blkback.c
+++ b/drivers/xen/blkback/blkback.c
@@ -166,38 +166,6 @@ static void free_req(struct pending_req *req)
wake_up(&blkbk->pending_free_wq);
}
-/*
- * Give back a reference count on the underlaying storage.
- * It is OK to make multiple calls in this function as it
- * resets the plug to NULL when it is done on the first call.
- */
-static void unplug_queue(struct blkif_st *blkif)
-{
- if (blkif->plug == NULL)
- return;
- if (blkif->plug->unplug_fn)
- blkif->plug->unplug_fn(blkif->plug);
- blk_put_queue(blkif->plug);
- blkif->plug = NULL;
-}
-
-/*
- * Take a reference count on the underlaying storage.
- * It is OK to call this multiple times as we check to make sure
- * not to double reference. We also give back a reference count
- * if it corresponds to another queue.
- */
-static void plug_queue(struct blkif_st *blkif, struct block_device *bdev)
-{
- struct request_queue *q = bdev_get_queue(bdev);
-
- if (q == blkif->plug)
- return;
- unplug_queue(blkif);
- blk_get_queue(q);
- blkif->plug = q;
-}
-
/*
* Unmap the grant references, and also remove the M2P over-rides
* used in the 'pending_req'.
@@ -280,7 +248,6 @@ int blkif_schedule(void *arg)
if (do_block_io_op(blkif))
blkif->waiting_reqs = 1;
- unplug_queue(blkif);
if (log_stats && time_after(jiffies, blkif->st_print))
print_stats(blkif);
@@ -456,6 +423,8 @@ static void dispatch_rw_block_io(struct blkif_st *blkif,
struct bio *bio = NULL;
int ret, i;
int operation;
+ struct blk_plug plug;
+ struct request_queue *q;
switch (req->operation) {
case BLKIF_OP_READ:
@@ -561,7 +530,8 @@ static void dispatch_rw_block_io(struct blkif_st *blkif,
}
/* Get a reference count for the disk queue and start sending I/O */
- plug_queue(blkif, preq.bdev);
+ blk_get_queue(q);
+ blk_start_plug(&plug);
/* We set it one so that the last submit_bio does not have to call
* atomic_inc.
@@ -620,11 +590,14 @@ static void dispatch_rw_block_io(struct blkif_st *blkif,
else if (operation == WRITE || operation == WRITE_BARRIER)
blkif->st_wr_sect += preq.nr_sects;
+ blk_finish_plug(&plug);
+ blk_put_queue(q);
return;
fail_flush:
fast_flush_area(pending_req);
fail_response:
+ /* Haven't submitted any bio's yet. */
make_response(blkif, req->id, req->operation, BLKIF_RSP_ERROR);
free_req(pending_req);
msleep(1); /* back off a bit */
@@ -634,7 +607,8 @@ static void dispatch_rw_block_io(struct blkif_st *blkif,
__end_block_io_op(pending_req, -EINVAL);
if (bio)
bio_put(bio);
- unplug_queue(blkif);
+ blk_finish_plug(&plug);
+ blk_put_queue(q);
msleep(1); /* back off a bit */
return;
}
diff --git a/drivers/xen/blkback/common.h b/drivers/xen/blkback/common.h
index be3fc93d8a31f..6257c11065915 100644
--- a/drivers/xen/blkback/common.h
+++ b/drivers/xen/blkback/common.h
@@ -79,7 +79,6 @@ struct blkif_st {
/* One thread per one blkif. */
struct task_struct *xenblkd;
unsigned int waiting_reqs;
- struct request_queue *plug;
/* statistics */
unsigned long st_print;
--
2.39.5