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dm mpath: reduce memory pressure when requeuing

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When multipath needs to requeue I/O in the block layer the per-request
context shouldn't be allocated, as it will be freed immediately
afterwards anyway.  Avoiding this memory allocation will reduce memory
pressure during requeuing.

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 2014-02-28 15:33:46 +01:00 committed by Mike Snitzer
parent 3e9f1be1b4
commit e3bde04f1e
1 changed files with 15 additions and 23 deletions
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38
drivers/md/dm-mpath.c
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@ -378,12 +378,12 @@ static int __must_push_back(struct multipath *m)
static int map_io(struct multipath *m, struct request *clone,
union map_info *map_context)
{
int r = DM_MAPIO_REMAPPED;
int r = DM_MAPIO_REQUEUE;
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;
struct dm_mpath_io *mpio;
spin_lock_irqsave(&m->lock, flags);
@ -396,27 +396,29 @@ static int map_io(struct multipath *m, struct request *clone,
if (pgpath) {
if (pg_ready(m)) {
if (set_mapinfo(m, map_context) < 0)
/* ENOMEM, requeue */
goto out_unlock;
bdev = pgpath->path.dev->bdev;
clone->q = bdev_get_queue(bdev);
clone->rq_disk = bdev->bd_disk;
clone->cmd_flags |= REQ_FAILFAST_TRANSPORT;
mpio = map_context->ptr;
mpio->pgpath = pgpath;
mpio->nr_bytes = nr_bytes;
if (pgpath->pg->ps.type->start_io)
pgpath->pg->ps.type->start_io(&pgpath->pg->ps,
&pgpath->path,
nr_bytes);
} else {
__pg_init_all_paths(m);
r = DM_MAPIO_REQUEUE;
r = DM_MAPIO_REMAPPED;
goto out_unlock;
}
} else {
/* No path */
if (__must_push_back(m))
r = DM_MAPIO_REQUEUE;
else
r = -EIO; /* Failed */
}
__pg_init_all_paths(m);
} else if (!__must_push_back(m))
r = -EIO; /* Failed */
out_unlock:
spin_unlock_irqrestore(&m->lock, flags);
return r;
@ -912,19 +914,9 @@ static void multipath_dtr(struct dm_target *ti)
static int multipath_map(struct dm_target *ti, struct request *clone,
union map_info *map_context)
{
int r;
struct multipath *m = (struct multipath *) ti->private;
if (set_mapinfo(m, map_context) < 0)
/* ENOMEM, requeue */
return DM_MAPIO_REQUEUE;
clone->cmd_flags |= REQ_FAILFAST_TRANSPORT;
r = map_io(m, clone, map_context);
if (r < 0 || r == DM_MAPIO_REQUEUE)
clear_mapinfo(m, map_context);
return r;
return map_io(m, clone, map_context);
}
/*