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dm mpath: detect invalid map_context

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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: Jun'ichi Nomura <j-nomura@ce.jp.nec.com>
Cc: Mike Snitzer <snitzer@redhat.com>
Acked-by: Hannes Reinecke <hare@suse.de>
Tested-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Acked-by: Dave Wysochanski <dwysocha@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
This commit is contained in:
Jun'ichi Nomura 2012-03-28 18:41:25 +01:00 committed by Alasdair G Kergon
parent 4d7b38b7d9
commit 466891f995
1 changed files with 32 additions and 14 deletions
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46
drivers/md/dm-mpath.c
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@ -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;
}