Hi Hannes,
On 03/20/12 00:39, Hannes Reinecke wrote:
> The map_context pointer should always be set. However, we
> have reports that upon requeing it is not set correctly.
> So add a BUG_ON() statement and clear the pointer to
> track the issue properly.
>
> Cc: Alasdair Kergon <agk@redhat.com>
> Cc: Mike Snitzer <snitzer@redhat.com>
> Signed-off-by: Hannes Reinecke <hare@suse.de>
> Tested-by: Heiko Carstens <heiko.carstens@de.ibm.com>
> Acked-by: Dave Wysochanski <dwysocha@redhat.com>
> ---
> drivers/md/dm-mpath.c | 9 ++++++++-
> 1 files changed, 8 insertions(+), 1 deletions(-)
>
> diff --git a/drivers/md/dm-mpath.c b/drivers/md/dm-mpath.c
> index 801d92d..2ed316e 100644
> --- a/drivers/md/dm-mpath.c
> +++ b/drivers/md/dm-mpath.c
> @@ -441,11 +441,13 @@ static void dispatch_queued_ios(struct multipath *m)
> r = map_io(m, clone, mpio, 1);
> if (r < 0) {
> mempool_free(mpio, m->mpio_pool);
> + info->ptr = NULL;
> 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);
> + info->ptr = NULL;
> dm_requeue_unmapped_request(clone);
> }
> }
If we want to ensure info->ptr is either valid or NULL,
how about introducing a function to do it like this?
---
Jun'ichi Nomura, NEC Corporation
diff --git a/drivers/md/dm-mpath.c b/drivers/md/dm-mpath.c
index 801d92d..c6c33b0 100644
--- a/drivers/md/dm-mpath.c
+++ b/drivers/md/dm-mpath.c
@@ -226,6 +226,26 @@ 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 +361,14 @@ 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 +444,6 @@ 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 +456,15 @@ 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 +927,16 @@ 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 +1276,15 @@ 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;
}
--
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dm-mpath: Track invalid map_context
