Commit 3e9f1be1 authored by Hannes Reinecke's avatar Hannes Reinecke Committed by Mike Snitzer
Browse files

dm mpath: remove process_queued_ios() 



process_queued_ios() has served 3 functions:
  1) select pg and pgpath if none is selected
  2) start pg_init if requested
  3) dispatch queued IOs when pg is ready

Basically, a call to queue_work(process_queued_ios) can be replaced by
dm_table_run_md_queue_async(), which runs request queue and ends up
calling map_io(), which does 1), 2) and 3).

Exception is when !pg_ready() (which means either pg_init is running or
requested), then multipath_busy() prevents map_io() being called from
request_fn.

If pg_init is running, it should be ok as long as pg_init_done() does
the right thing when pg_init is completed, I.e.: restart pg_init if
!pg_ready() or call dm_table_run_md_queue_async() to kick map_io().

If pg_init is requested, we have to make sure the request is detected
and pg_init will be started.  pg_init is requested in 3 places:
  a) __choose_pgpath() in map_io()
  b) __choose_pgpath() in multipath_ioctl()
  c) pg_init retry in pg_init_done()
a) is ok because map_io() calls __pg_init_all_paths(), which does 2).
b) needs a call to __pg_init_all_paths(), which does 2).
c) needs a call to __pg_init_all_paths(), which does 2).

So this patch removes process_queued_ios() and ensures that
__pg_init_all_paths() is called at the appropriate locations.

Signed-off-by: default avatarHannes Reinecke <hare@suse.de>
Signed-off-by: default avatarMike Snitzer <snitzer@redhat.com>
Reviewed-by: default avatarJun'ichi Nomura <j-nomura@ce.jp.nec.com>
parent e8099177

drivers/md/dm-mpath.c

+27 −42
Original line number Diff line number Diff line
@@ -93,8 +93,6 @@ struct multipath { 
	unsigned pg_init_count;		/* Number of times pg_init called */

	unsigned pg_init_delay_msecs;	/* Number of msecs before pg_init retry */



	struct work_struct process_queued_ios;



	struct work_struct trigger_event;



	/*
@@ -119,7 +117,6 @@ typedef int (*action_fn) (struct pgpath *pgpath); 
static struct kmem_cache *_mpio_cache;



static struct workqueue_struct *kmultipathd, *kmpath_handlerd;

static void process_queued_ios(struct work_struct *work);

static void trigger_event(struct work_struct *work);

static void activate_path(struct work_struct *work);

static int __pgpath_busy(struct pgpath *pgpath);
@@ -197,7 +194,6 @@ static struct multipath *alloc_multipath(struct dm_target *ti) 
		spin_lock_init(&m->lock);

		m->queue_io = 1;

		m->pg_init_delay_msecs = DM_PG_INIT_DELAY_DEFAULT;

		INIT_WORK(&m->process_queued_ios, process_queued_ios);

		INIT_WORK(&m->trigger_event, trigger_event);

		init_waitqueue_head(&m->pg_init_wait);

		mutex_init(&m->work_mutex);
@@ -254,16 +250,21 @@ static void clear_mapinfo(struct multipath *m, union map_info *info) 
 * Path selection

 *-----------------------------------------------*/



static void __pg_init_all_paths(struct multipath *m)

static int __pg_init_all_paths(struct multipath *m)

{

	struct pgpath *pgpath;

	unsigned long pg_init_delay = 0;



	if (m->pg_init_in_progress || m->pg_init_disabled)

		return;

		return 0;



	m->pg_init_count++;

	m->pg_init_required = 0;



	/* Check here to reset pg_init_required */

	if (!m->current_pg)

		return 0;



	if (m->pg_init_delay_retry)

		pg_init_delay = msecs_to_jiffies(m->pg_init_delay_msecs != DM_PG_INIT_DELAY_DEFAULT ?

						 m->pg_init_delay_msecs : DM_PG_INIT_DELAY_MSECS);
@@ -275,6 +276,7 @@ static void __pg_init_all_paths(struct multipath *m) 
				       pg_init_delay))

			m->pg_init_in_progress++;

	}

	return m->pg_init_in_progress;

}



static void __switch_pg(struct multipath *m, struct pgpath *pgpath)
@@ -436,40 +438,13 @@ static int queue_if_no_path(struct multipath *m, unsigned queue_if_no_path, 
		m->saved_queue_if_no_path = queue_if_no_path;

	m->queue_if_no_path = queue_if_no_path;

	if (!m->queue_if_no_path)

		queue_work(kmultipathd, &m->process_queued_ios);

		dm_table_run_md_queue_async(m->ti->table);



	spin_unlock_irqrestore(&m->lock, flags);



	return 0;

}



static void process_queued_ios(struct work_struct *work)

{

	struct multipath *m =

		container_of(work, struct multipath, process_queued_ios);

	struct pgpath *pgpath = NULL;

	unsigned must_queue = 1;

	unsigned long flags;



	spin_lock_irqsave(&m->lock, flags);



	if (!m->current_pgpath)

		__choose_pgpath(m, 0);



	pgpath = m->current_pgpath;



	if ((pgpath && !m->queue_io) ||

	    (!pgpath && !m->queue_if_no_path))

		must_queue = 0;



	if (pgpath && m->pg_init_required)

		__pg_init_all_paths(m);



	spin_unlock_irqrestore(&m->lock, flags);

	if (!must_queue)

		dm_table_run_md_queue_async(m->ti->table);

}



/*

 * An event is triggered whenever a path is taken out of use.

 * Includes path failure and PG bypass.
@@ -1016,7 +991,7 @@ static int reinstate_path(struct pgpath *pgpath) 


	if (!m->nr_valid_paths++) {

		m->current_pgpath = NULL;

		queue_work(kmultipathd, &m->process_queued_ios);

		dm_table_run_md_queue_async(m->ti->table);

	} else if (m->hw_handler_name && (m->current_pg == pgpath->pg)) {

		if (queue_work(kmpath_handlerd, &pgpath->activate_path.work))

			m->pg_init_in_progress++;
@@ -1212,11 +1187,12 @@ static void pg_init_done(void *data, int errors) 
		/* Activations of other paths are still on going */

		goto out;



	if (!m->pg_init_required)

		m->queue_io = 0;



	if (m->pg_init_required) {

		m->pg_init_delay_retry = delay_retry;

	queue_work(kmultipathd, &m->process_queued_ios);

		if (__pg_init_all_paths(m))

			goto out;

	}

	m->queue_io = 0;



	/*

	 * Wake up any thread waiting to suspend.
@@ -1592,8 +1568,17 @@ static int multipath_ioctl(struct dm_target *ti, unsigned int cmd, 
			r = err;

	}



	if (r == -ENOTCONN && !fatal_signal_pending(current))

		queue_work(kmultipathd, &m->process_queued_ios);

	if (r == -ENOTCONN && !fatal_signal_pending(current)) {

		spin_lock_irqsave(&m->lock, flags);

		if (!m->current_pg) {

			/* Path status changed, redo selection */

			__choose_pgpath(m, 0);

		}

		if (m->pg_init_required)

			__pg_init_all_paths(m);

		spin_unlock_irqrestore(&m->lock, flags);

		dm_table_run_md_queue_async(m->ti->table);

	}



	return r ? : __blkdev_driver_ioctl(bdev, mode, cmd, arg);

}

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