| Message ID | 1407956023-32372-2-git-send-email-bmarzins@redhat.com (mailing list archive) |
|---|---|
| State | Accepted, archived |
| Delegated to: | Mike Snitzer |
| Headers | show |
On Wed, Aug 13, 2014 at 2:53 PM, Benjamin Marzinski <bmarzins@redhat.com> wrote: > Commit e809917735ebf1b9a56c24e877ce0d320baee2ec changed the code in > multipath_busy that checked if a multipath device was initializing a path. > It returned busy if queue_io was set on the device. However queue_io is set > when the table is loaded, and as long as the device was busy, multipath_map > wouldn't run to clear it upon receiving requsts. multipath_ioctl and > reinstate_path were still able to clear queue_io. But if no paths were > reinstated and the multipath device received no ioctls after the table > reload, all requests to it would simply queue. > > This patch switches the multipath_busy code to check for a pending or in > progress path initialization, without using queue_io. This means incoming > requests will allow multipath_map to initialize paths and clear queue_io. This was already addressed with commit 7a7a3b45fe ("dm mpath: fix IO hang due to logic bug in multipath_busy"). > This patch also changes __choose_pgpath to make it clear queue_io if there > are no valid paths, since there are obviously no paths that can be > initialized. Can you elaborate on why this is needed? If it still is then it needs to be rebased. -- dm-devel mailing list dm-devel@redhat.com https://www.redhat.com/mailman/listinfo/dm-devel
On Wed, Aug 13, 2014 at 10:46:15PM -0400, Mike Snitzer wrote: > On Wed, Aug 13, 2014 at 2:53 PM, Benjamin Marzinski <bmarzins@redhat.com> wrote: > > Commit e809917735ebf1b9a56c24e877ce0d320baee2ec changed the code in > > multipath_busy that checked if a multipath device was initializing a path. > > It returned busy if queue_io was set on the device. However queue_io is set > > when the table is loaded, and as long as the device was busy, multipath_map > > wouldn't run to clear it upon receiving requsts. multipath_ioctl and > > reinstate_path were still able to clear queue_io. But if no paths were > > reinstated and the multipath device received no ioctls after the table > > reload, all requests to it would simply queue. > > > > This patch switches the multipath_busy code to check for a pending or in > > progress path initialization, without using queue_io. This means incoming > > requests will allow multipath_map to initialize paths and clear queue_io. > > This was already addressed with commit 7a7a3b45fe ("dm mpath: fix IO > hang due to logic bug in multipath_busy"). > > > This patch also changes __choose_pgpath to make it clear queue_io if there > > are no valid paths, since there are obviously no paths that can be > > initialized. > > Can you elaborate on why this is needed? If it still is then it needs > to be rebased. For a while now, it's been possible to create a multipath table with no devices. With this patch set, it will be even easier to reload a multipath device with no valid paths (since multipath now supports reloading failed paths). In these scenarios, we still need to disable queue_io, so that IOs to the device will not just back up. -Ben > > -- > dm-devel mailing list > dm-devel@redhat.com > https://www.redhat.com/mailman/listinfo/dm-devel -- dm-devel mailing list dm-devel@redhat.com https://www.redhat.com/mailman/listinfo/dm-devel
diff --git a/drivers/md/dm-mpath.c b/drivers/md/dm-mpath.c index 3f6fd9d..a0b83cb 100644 --- a/drivers/md/dm-mpath.c +++ b/drivers/md/dm-mpath.c @@ -317,8 +317,10 @@ static void __choose_pgpath(struct multipath *m, size_t nr_bytes) struct priority_group *pg; unsigned bypassed = 1; - if (!m->nr_valid_paths) + if (!m->nr_valid_paths) { + m->queue_io = 0; goto failed; + } /* Were we instructed to switch PG? */ if (m->next_pg) { @@ -1612,7 +1614,7 @@ static int multipath_busy(struct dm_target *ti) spin_lock_irqsave(&m->lock, flags); /* pg_init in progress, requeue until done */ - if (!pg_ready(m)) { + if (m->pg_init_required || m->pg_init_in_progress) { busy = 1; goto out; }
Commit e809917735ebf1b9a56c24e877ce0d320baee2ec changed the code in multipath_busy that checked if a multipath device was initializing a path. It returned busy if queue_io was set on the device. However queue_io is set when the table is loaded, and as long as the device was busy, multipath_map wouldn't run to clear it upon receiving requsts. multipath_ioctl and reinstate_path were still able to clear queue_io. But if no paths were reinstated and the multipath device received no ioctls after the table reload, all requests to it would simply queue. This patch switches the multipath_busy code to check for a pending or in progress path initialization, without using queue_io. This means incoming requests will allow multipath_map to initialize paths and clear queue_io. This patch also changes __choose_pgpath to make it clear queue_io if there are no valid paths, since there are obviously no paths that can be initialized. Signed-off-by: Benjamin Marzinski <bmarzins@redhat.com> --- drivers/md/dm-mpath.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-)