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Commit 466891f9 authored by Jun'ichi Nomura's avatar Jun'ichi Nomura Committed by Alasdair G Kergon
Browse files

dm mpath: detect invalid map_context 



The map_context pointer should always be set. However, we have reports
that upon requeuing it is not set correctly.  So add set and clear
functions with a BUG_ON() to track the issue properly.

Signed-off-by: default avatarJun'ichi Nomura <j-nomura@ce.jp.nec.com>
Cc: Mike Snitzer <snitzer@redhat.com>
Acked-by: default avatarHannes Reinecke <hare@suse.de>
Tested-by: default avatarHeiko Carstens <heiko.carstens@de.ibm.com>
Acked-by: default avatarDave Wysochanski <dwysocha@redhat.com>
Signed-off-by: default avatarAlasdair G Kergon <agk@redhat.com>
parent 4d7b38b7

drivers/md/dm-mpath.c

+32 −14
Original line number Diff line number Diff line
@@ -226,6 +226,27 @@ static void free_multipath(struct multipath *m) 
	kfree(m);

}



static int set_mapinfo(struct multipath *m, union map_info *info)

{

	struct dm_mpath_io *mpio;



	mpio = mempool_alloc(m->mpio_pool, GFP_ATOMIC);

	if (!mpio)

		return -ENOMEM;



	memset(mpio, 0, sizeof(*mpio));

	info->ptr = mpio;



	return 0;

}



static void clear_mapinfo(struct multipath *m, union map_info *info)

{

	struct dm_mpath_io *mpio = info->ptr;



	info->ptr = NULL;

	mempool_free(mpio, m->mpio_pool);

}



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

 * Path selection
@@ -341,13 +362,14 @@ static int __must_push_back(struct multipath *m) 
}



static int map_io(struct multipath *m, struct request *clone,

		  struct dm_mpath_io *mpio, unsigned was_queued)

		  union map_info *map_context, unsigned was_queued)

{

	int r = DM_MAPIO_REMAPPED;

	size_t nr_bytes = blk_rq_bytes(clone);

	unsigned long flags;

	struct pgpath *pgpath;

	struct block_device *bdev;

	struct dm_mpath_io *mpio = map_context->ptr;



	spin_lock_irqsave(&m->lock, flags);
@@ -423,7 +445,6 @@ static void dispatch_queued_ios(struct multipath *m) 
{

	int r;

	unsigned long flags;

	struct dm_mpath_io *mpio;

	union map_info *info;

	struct request *clone, *n;

	LIST_HEAD(cl);
@@ -436,16 +457,15 @@ static void dispatch_queued_ios(struct multipath *m) 
		list_del_init(&clone->queuelist);



		info = dm_get_rq_mapinfo(clone);

		mpio = info->ptr;



		r = map_io(m, clone, mpio, 1);

		r = map_io(m, clone, info, 1);

		if (r < 0) {

			mempool_free(mpio, m->mpio_pool);

			clear_mapinfo(m, info);

			dm_kill_unmapped_request(clone, r);

		} else if (r == DM_MAPIO_REMAPPED)

			dm_dispatch_request(clone);

		else if (r == DM_MAPIO_REQUEUE) {

			mempool_free(mpio, m->mpio_pool);

			clear_mapinfo(m, info);

			dm_requeue_unmapped_request(clone);

		}

	}
@@ -908,20 +928,16 @@ static int multipath_map(struct dm_target *ti, struct request *clone, 
			 union map_info *map_context)

{

	int r;

	struct dm_mpath_io *mpio;

	struct multipath *m = (struct multipath *) ti->private;



	mpio = mempool_alloc(m->mpio_pool, GFP_ATOMIC);

	if (!mpio)

	if (set_mapinfo(m, map_context) < 0)

		/* ENOMEM, requeue */

		return DM_MAPIO_REQUEUE;

	memset(mpio, 0, sizeof(*mpio));



	map_context->ptr = mpio;

	clone->cmd_flags |= REQ_FAILFAST_TRANSPORT;

	r = map_io(m, clone, mpio, 0);

	r = map_io(m, clone, map_context, 0);

	if (r < 0 || r == DM_MAPIO_REQUEUE)

		mempool_free(mpio, m->mpio_pool);

		clear_mapinfo(m, map_context);



	return r;

}
@@ -1261,13 +1277,15 @@ static int multipath_end_io(struct dm_target *ti, struct request *clone, 
	struct path_selector *ps;

	int r;



	BUG_ON(!mpio);



	r  = do_end_io(m, clone, error, mpio);

	if (pgpath) {

		ps = &pgpath->pg->ps;

		if (ps->type->end_io)

			ps->type->end_io(ps, &pgpath->path, mpio->nr_bytes);

	}

	mempool_free(mpio, m->mpio_pool);

	clear_mapinfo(m, map_context);



	return r;

}