[dm-devel] [PATCH 07/12] md/raid5: add simple plugging infrastructure.
NeilBrown
neilb at suse.de
Thu Apr 15 06:43:02 UTC 2010
md/raid5 uses the plugging infrastructure provided by the block layer
and 'struct request_queue'. However when we plug raid5 under dm there
is no request queue so we cannot use that.
So create a similar infrastructure that is much lighter weight and use
it for raid5.
Signed-off-by: NeilBrown <neilb at suse.de>
---
drivers/md/md.c | 45 +++++++++++++++++++++++++++++++++++++++++++++
drivers/md/md.h | 21 +++++++++++++++++++++
drivers/md/raid5.c | 39 +++++++++++++++++++++++++--------------
drivers/md/raid5.h | 3 +++
4 files changed, 94 insertions(+), 14 deletions(-)
diff --git a/drivers/md/md.c b/drivers/md/md.c
index 2042b1c..49336e7 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -383,6 +383,51 @@ void md_barrier_request(mddev_t *mddev, struct bio *bio)
}
EXPORT_SYMBOL(md_barrier_request);
+/* Support for plugging.
+ * This mirrors the plugging support in request_queue, but does not
+ * require having a whole queue
+ */
+static void plugger_work(struct work_struct *work)
+{
+ struct plug_handle *plug =
+ container_of(work, struct plug_handle, unplug_work);
+ plug->unplug_fn(plug);
+}
+static void plugger_timeout(unsigned long data)
+{
+ struct plug_handle *plug = (void*)data;
+ kblockd_schedule_work(NULL, &plug->unplug_work);
+}
+void plugger_init(struct plug_handle *plug,
+ void (*unplug_fn)(struct plug_handle *))
+{
+ plug->unplug_flag = 0;
+ plug->unplug_fn = unplug_fn;
+ init_timer(&plug->unplug_timer);
+ plug->unplug_timer.function = plugger_timeout;
+ plug->unplug_timer.data = (unsigned long)plug;
+ INIT_WORK(&plug->unplug_work, plugger_work);
+}
+EXPORT_SYMBOL_GPL(plugger_init);
+
+void plugger_set_plug(struct plug_handle *plug)
+{
+ if (!test_and_set_bit(PLUGGED_FLAG, &plug->unplug_flag))
+ mod_timer(&plug->unplug_timer, jiffies + msecs_to_jiffies(3)+1);
+}
+EXPORT_SYMBOL_GPL(plugger_set_plug);
+
+int plugger_remove_plug(struct plug_handle *plug)
+{
+ if (test_and_clear_bit(PLUGGED_FLAG, &plug->unplug_flag)) {
+ del_timer(&plug->unplug_timer);
+ return 1;
+ } else
+ return 0;
+}
+EXPORT_SYMBOL_GPL(plugger_remove_plug);
+
+
static inline mddev_t *mddev_get(mddev_t *mddev)
{
atomic_inc(&mddev->active);
diff --git a/drivers/md/md.h b/drivers/md/md.h
index 09a2881..1c14c33 100644
--- a/drivers/md/md.h
+++ b/drivers/md/md.h
@@ -29,6 +29,26 @@
typedef struct mddev_s mddev_t;
typedef struct mdk_rdev_s mdk_rdev_t;
+/* generic plugging support - like that provided with request_queue,
+ * but does not require a request_queue
+ */
+struct plug_handle {
+ void (*unplug_fn)(struct plug_handle *);
+ struct timer_list unplug_timer;
+ struct work_struct unplug_work;
+ unsigned long unplug_flag;
+};
+#define PLUGGED_FLAG 1
+void plugger_init(struct plug_handle *plug,
+ void (*unplug_fn)(struct plug_handle *));
+void plugger_set_plug(struct plug_handle *plug);
+int plugger_remove_plug(struct plug_handle *plug);
+static inline void plugger_flush(struct plug_handle *plug)
+{
+ del_timer_sync(&plug->unplug_timer);
+ cancel_work_sync(&plug->unplug_work);
+}
+
/*
* MD's 'extended' device
*/
@@ -449,6 +469,7 @@ static inline void safe_put_page(struct page *p)
if (p) put_page(p);
}
+
extern int register_md_personality(struct mdk_personality *p);
extern int unregister_md_personality(struct mdk_personality *p);
extern mdk_thread_t * md_register_thread(void (*run) (mddev_t *mddev),
diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index aaaed29..ac63012 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -200,11 +200,11 @@ static void __release_stripe(raid5_conf_t *conf, struct stripe_head *sh)
if (test_bit(STRIPE_HANDLE, &sh->state)) {
if (test_bit(STRIPE_DELAYED, &sh->state)) {
list_add_tail(&sh->lru, &conf->delayed_list);
- blk_plug_device(conf->mddev->queue);
+ plugger_set_plug(&conf->plug);
} else if (test_bit(STRIPE_BIT_DELAY, &sh->state) &&
sh->bm_seq - conf->seq_write > 0) {
list_add_tail(&sh->lru, &conf->bitmap_list);
- blk_plug_device(conf->mddev->queue);
+ plugger_set_plug(&conf->plug);
} else {
clear_bit(STRIPE_BIT_DELAY, &sh->state);
list_add_tail(&sh->lru, &conf->handle_list);
@@ -364,7 +364,7 @@ static struct stripe_head *__find_stripe(raid5_conf_t *conf, sector_t sector,
}
static void unplug_slaves(mddev_t *mddev);
-static void raid5_unplug_device(struct request_queue *q);
+static void raid5_unplug_device(raid5_conf_t *conf);
static struct stripe_head *
get_active_stripe(raid5_conf_t *conf, sector_t sector,
@@ -394,7 +394,7 @@ get_active_stripe(raid5_conf_t *conf, sector_t sector,
< (conf->max_nr_stripes *3/4)
|| !conf->inactive_blocked),
conf->device_lock,
- raid5_unplug_device(conf->mddev->queue)
+ raid5_unplug_device(conf)
);
conf->inactive_blocked = 0;
} else
@@ -3535,7 +3535,7 @@ static void raid5_activate_delayed(raid5_conf_t *conf)
list_add_tail(&sh->lru, &conf->hold_list);
}
} else
- blk_plug_device(conf->mddev->queue);
+ plugger_set_plug(&conf->plug);
}
static void activate_bit_delay(raid5_conf_t *conf)
@@ -3576,23 +3576,33 @@ static void unplug_slaves(mddev_t *mddev)
rcu_read_unlock();
}
-static void raid5_unplug_device(struct request_queue *q)
+static void raid5_unplug_device(raid5_conf_t *conf)
{
- mddev_t *mddev = q->queuedata;
- raid5_conf_t *conf = mddev->private;
unsigned long flags;
spin_lock_irqsave(&conf->device_lock, flags);
- if (blk_remove_plug(q)) {
+ if (plugger_remove_plug(&conf->plug)) {
conf->seq_flush++;
raid5_activate_delayed(conf);
}
- md_wakeup_thread(mddev->thread);
+ md_wakeup_thread(conf->mddev->thread);
spin_unlock_irqrestore(&conf->device_lock, flags);
- unplug_slaves(mddev);
+ unplug_slaves(conf->mddev);
+}
+
+static void raid5_unplug(struct plug_handle *plug)
+{
+ raid5_conf_t *conf = container_of(plug, raid5_conf_t, plug);
+ raid5_unplug_device(conf);
+}
+
+static void raid5_unplug_queue(struct request_queue *q)
+{
+ mddev_t *mddev = q->queuedata;
+ raid5_unplug_device(mddev->private);
}
int md_raid5_congested(mddev_t *mddev, int bits)
@@ -4002,7 +4012,7 @@ static int make_request(mddev_t *mddev, struct bio * bi)
* add failed due to overlap. Flush everything
* and wait a while
*/
- raid5_unplug_device(mddev->queue);
+ raid5_unplug_device(conf);
release_stripe(sh);
schedule();
goto retry;
@@ -5100,6 +5110,7 @@ static int run(mddev_t *mddev)
mdname(mddev));
md_set_array_sectors(mddev, raid5_size(mddev, 0, 0));
+ plugger_init(&conf->plug, raid5_unplug);
if (mddev->queue) {
/* read-ahead size must cover two whole stripes, which
* is 2 * (datadisks) * chunksize where 'n' is the
@@ -5119,7 +5130,7 @@ static int run(mddev_t *mddev)
mddev->queue->queue_lock = &conf->device_lock;
- mddev->queue->unplug_fn = raid5_unplug_device;
+ mddev->queue->unplug_fn = raid5_unplug_queue;
chunk_size = mddev->chunk_sectors << 9;
blk_queue_io_min(mddev->queue, chunk_size);
@@ -5153,7 +5164,7 @@ static int stop(mddev_t *mddev)
mddev->thread = NULL;
if (mddev->queue)
mddev->queue->backing_dev_info.congested_fn = NULL;
- blk_sync_queue(mddev->queue); /* the unplug fn references 'conf'*/
+ plugger_flush(&conf->plug); /* the unplug fn references 'conf'*/
free_conf(conf);
mddev->private = NULL;
mddev->to_remove = &raid5_attrs_group;
diff --git a/drivers/md/raid5.h b/drivers/md/raid5.h
index 6641789..4dc58bf 100644
--- a/drivers/md/raid5.h
+++ b/drivers/md/raid5.h
@@ -398,6 +398,9 @@ struct raid5_private_data {
* (fresh device added).
* Cleared when a sync completes.
*/
+
+ struct plug_handle plug;
+
/* per cpu variables */
struct raid5_percpu {
struct page *spare_page; /* Used when checking P/Q in raid6 */
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