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xen/blkback: remove per-queue plugging 

commit 7eaceaccab ("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>
This commit is contained in:
Konrad Rzeszutek Wilk 2011-04-14 17:58:19 -04:00
parent 2e9977c21f
commit 0faa8cca88
2 changed files with 9 additions and 36 deletions
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44
drivers/xen/blkback/blkback.c
View File

@ -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;
}

1
drivers/xen/blkback/common.h
View File

@ -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;