dm mpath: push back requests instead of queueing
There is no reason why multipath needs to queue requests internally for queue_if_no_path or pg_init; we should rather push them back onto the request queue. And while we're at it we can simplify the conditional statement in map_io() to make it easier to read. Since mpath no longer does internal queuing of I/O the table info no longer emits the internal queue_size. Instead it displays 1 if queuing is being used or 0 if it is not. Signed-off-by: Hannes Reinecke <hare@suse.de> Signed-off-by: Mike Snitzer <snitzer@redhat.com> Reviewed-by: Jun'ichi Nomura <j-nomura@ce.jp.nec.com>
This commit is contained in:
Hannes Reinecke
Mike Snitzer
parent
9974fa2c6a
commit
e809917735
@ -93,9 +93,7 @@ struct multipath {
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unsigned pg_init_count; /* Number of times pg_init called */
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unsigned pg_init_delay_msecs; /* Number of msecs before pg_init retry */
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unsigned queue_size;
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struct work_struct process_queued_ios;
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struct list_head queued_ios;
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struct work_struct trigger_event;
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@ -124,6 +122,7 @@ static struct workqueue_struct *kmultipathd, *kmpath_handlerd;
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static void process_queued_ios(struct work_struct *work);
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static void trigger_event(struct work_struct *work);
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static void activate_path(struct work_struct *work);
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static int __pgpath_busy(struct pgpath *pgpath);
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/*-----------------------------------------------
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@ -195,7 +194,6 @@ static struct multipath *alloc_multipath(struct dm_target *ti)
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m = kzalloc(sizeof(*m), GFP_KERNEL);
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if (m) {
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INIT_LIST_HEAD(&m->priority_groups);
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INIT_LIST_HEAD(&m->queued_ios);
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spin_lock_init(&m->lock);
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m->queue_io = 1;
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m->pg_init_delay_msecs = DM_PG_INIT_DELAY_DEFAULT;
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@ -368,12 +366,15 @@ failed:
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*/
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static int __must_push_back(struct multipath *m)
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{
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return (m->queue_if_no_path != m->saved_queue_if_no_path &&
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dm_noflush_suspending(m->ti));
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return (m->queue_if_no_path ||
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(m->queue_if_no_path != m->saved_queue_if_no_path &&
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dm_noflush_suspending(m->ti)));
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}
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#define pg_ready(m) (!(m)->queue_io && !(m)->pg_init_required)
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static int map_io(struct multipath *m, struct request *clone,
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union map_info *map_context, unsigned was_queued)
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union map_info *map_context)
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{
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int r = DM_MAPIO_REMAPPED;
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size_t nr_bytes = blk_rq_bytes(clone);
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@ -391,37 +392,28 @@ static int map_io(struct multipath *m, struct request *clone,
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pgpath = m->current_pgpath;
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if (was_queued)
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m->queue_size--;
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if (m->pg_init_required) {
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if (!m->pg_init_in_progress)
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queue_work(kmultipathd, &m->process_queued_ios);
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r = DM_MAPIO_REQUEUE;
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} else if ((pgpath && m->queue_io) ||
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(!pgpath && m->queue_if_no_path)) {
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/* Queue for the daemon to resubmit */
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list_add_tail(&clone->queuelist, &m->queued_ios);
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m->queue_size++;
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if (!m->queue_io)
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queue_work(kmultipathd, &m->process_queued_ios);
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pgpath = NULL;
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r = DM_MAPIO_SUBMITTED;
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} else if (pgpath) {
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bdev = pgpath->path.dev->bdev;
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clone->q = bdev_get_queue(bdev);
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clone->rq_disk = bdev->bd_disk;
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} else if (__must_push_back(m))
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r = DM_MAPIO_REQUEUE;
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else
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r = -EIO; /* Failed */
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mpio->pgpath = pgpath;
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mpio->nr_bytes = nr_bytes;
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if (r == DM_MAPIO_REMAPPED && pgpath->pg->ps.type->start_io)
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pgpath->pg->ps.type->start_io(&pgpath->pg->ps, &pgpath->path,
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nr_bytes);
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if (pgpath) {
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if (pg_ready(m)) {
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bdev = pgpath->path.dev->bdev;
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clone->q = bdev_get_queue(bdev);
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clone->rq_disk = bdev->bd_disk;
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mpio->pgpath = pgpath;
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mpio->nr_bytes = nr_bytes;
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if (pgpath->pg->ps.type->start_io)
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pgpath->pg->ps.type->start_io(&pgpath->pg->ps,
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&pgpath->path,
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nr_bytes);
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} else {
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__pg_init_all_paths(m);
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r = DM_MAPIO_REQUEUE;
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}
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} else {
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/* No path */
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if (__must_push_back(m))
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r = DM_MAPIO_REQUEUE;
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else
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r = -EIO; /* Failed */
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}
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spin_unlock_irqrestore(&m->lock, flags);
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@ -443,7 +435,7 @@ static int queue_if_no_path(struct multipath *m, unsigned queue_if_no_path,
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else
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m->saved_queue_if_no_path = queue_if_no_path;
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m->queue_if_no_path = queue_if_no_path;
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if (!m->queue_if_no_path && m->queue_size)
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if (!m->queue_if_no_path)
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queue_work(kmultipathd, &m->process_queued_ios);
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spin_unlock_irqrestore(&m->lock, flags);
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@ -451,40 +443,6 @@ static int queue_if_no_path(struct multipath *m, unsigned queue_if_no_path,
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return 0;
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}
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/*-----------------------------------------------------------------
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* The multipath daemon is responsible for resubmitting queued ios.
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*---------------------------------------------------------------*/
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static void dispatch_queued_ios(struct multipath *m)
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{
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int r;
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unsigned long flags;
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union map_info *info;
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struct request *clone, *n;
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LIST_HEAD(cl);
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spin_lock_irqsave(&m->lock, flags);
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list_splice_init(&m->queued_ios, &cl);
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spin_unlock_irqrestore(&m->lock, flags);
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list_for_each_entry_safe(clone, n, &cl, queuelist) {
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list_del_init(&clone->queuelist);
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info = dm_get_rq_mapinfo(clone);
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r = map_io(m, clone, info, 1);
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if (r < 0) {
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clear_mapinfo(m, info);
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dm_kill_unmapped_request(clone, r);
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} else if (r == DM_MAPIO_REMAPPED)
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dm_dispatch_request(clone);
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else if (r == DM_MAPIO_REQUEUE) {
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clear_mapinfo(m, info);
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dm_requeue_unmapped_request(clone);
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}
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}
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}
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static void process_queued_ios(struct work_struct *work)
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{
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struct multipath *m =
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@ -509,7 +467,7 @@ static void process_queued_ios(struct work_struct *work)
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spin_unlock_irqrestore(&m->lock, flags);
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if (!must_queue)
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dispatch_queued_ios(m);
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dm_table_run_md_queue_async(m->ti->table);
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}
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/*
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@ -987,7 +945,7 @@ static int multipath_map(struct dm_target *ti, struct request *clone,
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return DM_MAPIO_REQUEUE;
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clone->cmd_flags |= REQ_FAILFAST_TRANSPORT;
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r = map_io(m, clone, map_context, 0);
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r = map_io(m, clone, map_context);
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if (r < 0 || r == DM_MAPIO_REQUEUE)
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clear_mapinfo(m, map_context);
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@ -1056,7 +1014,7 @@ static int reinstate_path(struct pgpath *pgpath)
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pgpath->is_active = 1;
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if (!m->nr_valid_paths++ && m->queue_size) {
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if (!m->nr_valid_paths++) {
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m->current_pgpath = NULL;
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queue_work(kmultipathd, &m->process_queued_ios);
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} else if (m->hw_handler_name && (m->current_pg == pgpath->pg)) {
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@ -1435,7 +1393,7 @@ static void multipath_status(struct dm_target *ti, status_type_t type,
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/* Features */
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if (type == STATUSTYPE_INFO)
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DMEMIT("2 %u %u ", m->queue_size, m->pg_init_count);
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DMEMIT("2 %u %u ", m->queue_io, m->pg_init_count);
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else {
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DMEMIT("%u ", m->queue_if_no_path +
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(m->pg_init_retries > 0) * 2 +
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@ -1686,7 +1644,7 @@ static int multipath_busy(struct dm_target *ti)
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spin_lock_irqsave(&m->lock, flags);
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/* pg_init in progress, requeue until done */
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if (m->pg_init_in_progress) {
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if (!pg_ready(m)) {
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busy = 1;
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goto out;
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}
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@ -1739,7 +1697,7 @@ out:
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*---------------------------------------------------------------*/
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static struct target_type multipath_target = {
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.name = "multipath",
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.version = {1, 6, 0},
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.version = {1, 7, 0},
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.module = THIS_MODULE,
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.ctr = multipath_ctr,
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.dtr = multipath_dtr,
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