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Message-ID: <20100513043108.GB25523@redhat.com>
Date: Thu, 13 May 2010 00:31:09 -0400
From: Mike Snitzer <snitzer@...hat.com>
To: dm-devel@...hat.com
Cc: "Jun'ichi Nomura" <j-nomura@...jp.nec.com>,
Kiyoshi Ueda <k-ueda@...jp.nec.com>,
linux-kernel@...r.kernel.org, Vivek Goyal <vgoyal@...hat.com>,
Jens Axboe <jens.axboe@...cle.com>,
Nikanth Karthikesan <knikanth@...e.de>
Subject: [PATCH 2/2 v2] dm: only initialize full request_queue for
request-based device
Revert back to only allocating a minimalist request_queue structure
initially (needed for both bio and request-based DM). Initialization of
a full request_queue (request_fn, elevator, etc) is deferred until it is
known that the DM device is request-based.
dm_init_request_based_queue is now called at the end of a request-based
DM device's table load.
Otherwise bio-based DM devices will have an elevator, request_fn, etc.
As a result bio-based DM devices had an 'iosched/' tree as well as a
'scheduler' other than "none" in sysfs.
Signed-off-by: Mike Snitzer <snitzer@...hat.com>
---
drivers/md/dm-table.c | 5 ++++
drivers/md/dm.c | 64 +++++++++++++++++++++++++++++++++++-------------
drivers/md/dm.h | 2 +
3 files changed, 53 insertions(+), 18 deletions(-)
diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c
index 9924ea2..64a8578 100644
--- a/drivers/md/dm-table.c
+++ b/drivers/md/dm-table.c
@@ -829,6 +829,11 @@ int dm_table_set_type(struct dm_table *t)
return -EINVAL;
}
+ if (!dm_init_request_based_queue(t->md)) {
+ DMWARN("Cannot initialize queue for Request-based dm");
+ return -EINVAL;
+ }
+
t->type = DM_TYPE_REQUEST_BASED;
return 0;
diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index d21e128..b2171be 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -1886,22 +1886,10 @@ static struct mapped_device *alloc_dev(int minor)
INIT_LIST_HEAD(&md->uevent_list);
spin_lock_init(&md->uevent_lock);
- md->queue = blk_init_queue(dm_request_fn, NULL);
+ md->queue = blk_alloc_queue(GFP_KERNEL);
if (!md->queue)
goto bad_queue;
- /*
- * Request-based dm devices cannot be stacked on top of bio-based dm
- * devices. The type of this dm device has not been decided yet,
- * although we initialized the queue using blk_init_queue().
- * The type is decided at the first table loading time.
- * To prevent problematic device stacking, clear the queue flag
- * for request stacking support until then.
- *
- * This queue is new, so no concurrency on the queue_flags.
- */
- queue_flag_clear_unlocked(QUEUE_FLAG_STACKABLE, md->queue);
- md->saved_make_request_fn = md->queue->make_request_fn;
md->queue->queuedata = md;
md->queue->backing_dev_info.congested_fn = dm_any_congested;
md->queue->backing_dev_info.congested_data = md;
@@ -1909,11 +1897,6 @@ static struct mapped_device *alloc_dev(int minor)
blk_queue_bounce_limit(md->queue, BLK_BOUNCE_ANY);
md->queue->unplug_fn = dm_unplug_all;
blk_queue_merge_bvec(md->queue, dm_merge_bvec);
- blk_queue_softirq_done(md->queue, dm_softirq_done);
- blk_queue_prep_rq(md->queue, dm_prep_fn);
- blk_queue_lld_busy(md->queue, dm_lld_busy);
- blk_queue_ordered(md->queue, QUEUE_ORDERED_DRAIN_FLUSH,
- dm_rq_prepare_flush);
md->disk = alloc_disk(1);
if (!md->disk)
@@ -1968,6 +1951,51 @@ bad_module_get:
return NULL;
}
+/*
+ * Fully initialize the request_queue (elevator, ->request_fn, etc).
+ */
+int dm_init_request_based_queue(struct mapped_device *md)
+{
+ struct request_queue *q = NULL;
+
+ if (!md->queue)
+ return 0;
+
+ /*
+ * Avoid re-initializing the queue (and leaking the existing
+ * elevator) if dm_init_request_based_queue() was already used.
+ */
+ if (!md->queue->elevator) {
+ /* Fully initialize the queue */
+ q = blk_init_allocated_queue(md->queue, dm_request_fn, NULL);
+ if (!q)
+ return 0;
+ md->queue = q;
+ md->saved_make_request_fn = md->queue->make_request_fn;
+ blk_queue_make_request(md->queue, dm_request);
+ elv_register_queue(md->queue);
+ }
+
+ /*
+ * Request-based dm devices cannot be stacked on top of bio-based dm
+ * devices. The type of this dm device has not been decided yet.
+ * The type is decided at the first table loading time.
+ * To prevent problematic device stacking, clear the queue flag
+ * for request stacking support until then.
+ *
+ * This queue is new, so no concurrency on the queue_flags.
+ */
+ queue_flag_clear_unlocked(QUEUE_FLAG_STACKABLE, md->queue);
+
+ blk_queue_softirq_done(md->queue, dm_softirq_done);
+ blk_queue_prep_rq(md->queue, dm_prep_fn);
+ blk_queue_lld_busy(md->queue, dm_lld_busy);
+ blk_queue_ordered(md->queue, QUEUE_ORDERED_DRAIN_FLUSH,
+ dm_rq_prepare_flush);
+
+ return 1;
+}
+
static void unlock_fs(struct mapped_device *md);
static void free_dev(struct mapped_device *md)
diff --git a/drivers/md/dm.h b/drivers/md/dm.h
index bad1724..489feba 100644
--- a/drivers/md/dm.h
+++ b/drivers/md/dm.h
@@ -113,6 +113,8 @@ void dm_sysfs_exit(struct mapped_device *md);
struct kobject *dm_kobject(struct mapped_device *md);
struct mapped_device *dm_get_from_kobject(struct kobject *kobj);
+int dm_init_request_based_queue(struct mapped_device *md);
+
/*
* Targets for linear and striped mappings
*/
--
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