From: Hannes Reinecke <hare@xxxxxxx>
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@xxxxxxx>
Cc: Jun'ichi Nomura <j-nomura@xxxxxxxxxxxxx>
Signed-off-by: Mike Snitzer <snitzer@xxxxxxxxxx>
---
drivers/md/dm-mpath.c | 43 ++++++++++++++++++-------------------------
1 file changed, 18 insertions(+), 25 deletions(-)
diff --git a/drivers/md/dm-mpath.c b/drivers/md/dm-mpath.c
index b99cff0..07a00a2 100644
--- a/drivers/md/dm-mpath.c
+++ b/drivers/md/dm-mpath.c
@@ -372,12 +372,12 @@ 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);
@@ -390,29 +390,32 @@ static int map_io(struct multipath *m, struct request *clone,
if (pgpath) {
if (__pgpath_busy(pgpath))
- r = DM_MAPIO_REQUEUE;
- else if (pg_ready(m)) {
+ goto out_unlock;
+
+ 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, 0);
- 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, 0);
+ } else if (!__must_push_back(m))
+ r = -EIO; /* Failed */
+out_unlock:
spin_unlock_irqrestore(&m->lock, flags);
return r;
@@ -908,19 +911,9 @@ 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);
}
/*
--
1.8.1.4
--
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