lkml.org 
[lkml]   [2009]   [Aug]   [8]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
SubjectRe: [PATCH 1/2] Allow delaying initialization of queue after allocation
On Sat, Aug 08 2009 at 11:42am -0400,
Mike Snitzer <snitzer@redhat.com> wrote:

> On Sat, Aug 08 2009 at 12:55am -0400,
> Nikanth Karthikesan <knikanth@suse.de> wrote:
>
> > Export a way to delay initializing a request_queue after allocating it. This
> > is needed by device-mapper devices, as they create the queue on device
> > creation time, but they decide whether it would use the elevator and requests
> > only after first successful table load. Only request-based dm-devices use the
> > elevator and requests. Without this either one needs to initialize and free
> > the mempool and elevator, if it was a bio-based dm-device or leave it
> > allocated, as it is currently done.
> >
> > Signed-off-by: Nikanth Karthikesan <knikanth@suse.de>
>
> This patch needed to be refreshed to account for the changes from this
> recent commit: a4e7d46407d73f35d217013b363b79a8f8eafcaa
>
> I've attached a refreshed patch.

Err, I dropped a hunk in the process... here is the refreshed patch
inlined. Figured I'd save you the busy-work for when you get V2
together.

> Though I still have questions/feedback below.

Hopefully V2 will address my questions/feedback.

Regards,
Mike

---

Export a way to delay initializing a request_queue after allocating it. This
is needed by device-mapper devices, as they create the queue on device
creation time, but they decide whether it would use the elevator and requests
only after first successful table load. Only request-based dm-devices use the
elevator and requests. Without this either one needs to initialize and free
the mempool and elevator, if it was a bio-based dm-device or leave it
allocated, as it is currently done.

Signed-off-by: Nikanth Karthikesan <knikanth@suse.de>

---

Index: linux-2.6/block/blk-core.c
===================================================================
--- linux-2.6.orig/block/blk-core.c
+++ linux-2.6/block/blk-core.c
@@ -495,6 +495,8 @@ struct request_queue *blk_alloc_queue_no
if (!q)
return NULL;

+ q->node = node_id;
+
q->backing_dev_info.unplug_io_fn = blk_backing_dev_unplug;
q->backing_dev_info.unplug_io_data = q;
q->backing_dev_info.ra_pages =
@@ -569,12 +571,25 @@ blk_init_queue_node(request_fn_proc *rfn
if (!q)
return NULL;

- q->node = node_id;
- if (blk_init_free_list(q)) {
+ if (blk_init_allocated_queue(q, rfn, lock)) {
+ blk_put_queue(q);
kmem_cache_free(blk_requestq_cachep, q);
return NULL;
}

+ return q;
+}
+EXPORT_SYMBOL(blk_init_queue_node);
+
+int blk_init_allocated_queue(struct request_queue *q, request_fn_proc *rfn,
+ spinlock_t *lock)
+{
+ int err = 0;
+
+ err = blk_init_free_list(q);
+ if (err)
+ goto out;
+
q->request_fn = rfn;
q->prep_rq_fn = NULL;
q->unplug_fn = generic_unplug_device;
@@ -591,15 +606,20 @@ blk_init_queue_node(request_fn_proc *rfn
/*
* all done
*/
- if (!elevator_init(q, NULL)) {
- blk_queue_congestion_threshold(q);
- return q;
- }
+ err = elevator_init(q, NULL);
+ if (err)
+ goto free_and_out;

- blk_put_queue(q);
- return NULL;
+ blk_queue_congestion_threshold(q);
+
+ return 0;
+
+free_and_out:
+ mempool_destroy(q->rq.rq_pool);
+out:
+ return err;
}
-EXPORT_SYMBOL(blk_init_queue_node);
+EXPORT_SYMBOL(blk_init_allocated_queue);

int blk_get_queue(struct request_queue *q)
{
Index: linux-2.6/include/linux/blkdev.h
===================================================================
--- linux-2.6.orig/include/linux/blkdev.h
+++ linux-2.6/include/linux/blkdev.h
@@ -901,6 +901,8 @@ extern void blk_abort_queue(struct reque
extern struct request_queue *blk_init_queue_node(request_fn_proc *rfn,
spinlock_t *lock, int node_id);
extern struct request_queue *blk_init_queue(request_fn_proc *, spinlock_t *);
+extern int blk_init_allocated_queue(struct request_queue *q,
+ request_fn_proc *rfn, spinlock_t *lock);
extern void blk_cleanup_queue(struct request_queue *);
extern void blk_queue_make_request(struct request_queue *, make_request_fn *);
extern void blk_queue_bounce_limit(struct request_queue *, u64);

\
 
 \ /
  Last update: 2009-08-08 18:45    [W:0.596 / U:0.204 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site