Messages in this thread | | | Date | Mon, 26 Feb 2018 09:24:40 -0700 | From | Keith Busch <> | Subject | Re: [PATCH] nvme-multipath: fix sysfs dangerously created links |
| |
On Mon, Feb 26, 2018 at 05:51:23PM +0900, baegjae@gmail.com wrote: > From: Baegjae Sung <baegjae@gmail.com> > > If multipathing is enabled, each NVMe subsystem creates a head > namespace (e.g., nvme0n1) and multiple private namespaces > (e.g., nvme0c0n1 and nvme0c1n1) in sysfs. When creating links for > private namespaces, links of head namespace are used, so the > namespace creation order must be followed (e.g., nvme0n1 -> > nvme0c1n1). If the order is not followed, links of sysfs will be > incomplete or kernel panic will occur. > > The kernel panic was: > kernel BUG at fs/sysfs/symlink.c:27! > Call Trace: > nvme_mpath_add_disk_links+0x5d/0x80 [nvme_core] > nvme_validate_ns+0x5c2/0x850 [nvme_core] > nvme_scan_work+0x1af/0x2d0 [nvme_core] > > Correct order > Context A Context B > nvme0n1 > nvme0c0n1 nvme0c1n1 > > Incorrect order > Context A Context B > nvme0c1n1 > nvme0n1 > nvme0c0n1 > > The function of a head namespace creation is moved to maintain the > correct order. We verified the code with or without multipathing > using three vendors of dual-port NVMe SSDs. > > Signed-off-by: Baegjae Sung <baegjae@gmail.com>
Thanks, I see what you mean on the potential ordering problem here. Calling nvme_mpath_add_disk, though, before the 'head' has any namespace paths available looks like you'll get a lot of 'no path available' warnings during the bring-up. It should resolve itself shortly after, but the warnings will be a bit alarming, right?
> --- > drivers/nvme/host/core.c | 12 +++--------- > 1 file changed, 3 insertions(+), 9 deletions(-) > > diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c > index 0fe7ea35c221..28777b7352a5 100644 > --- a/drivers/nvme/host/core.c > +++ b/drivers/nvme/host/core.c > @@ -2844,7 +2844,7 @@ static struct nvme_ns_head *nvme_alloc_ns_head(struct nvme_ctrl *ctrl, > } > > static int nvme_init_ns_head(struct nvme_ns *ns, unsigned nsid, > - struct nvme_id_ns *id, bool *new) > + struct nvme_id_ns *id) > { > struct nvme_ctrl *ctrl = ns->ctrl; > bool is_shared = id->nmic & (1 << 0); > @@ -2860,8 +2860,7 @@ static int nvme_init_ns_head(struct nvme_ns *ns, unsigned nsid, > ret = PTR_ERR(head); > goto out_unlock; > } > - > - *new = true; > + nvme_mpath_add_disk(head); > } else { > struct nvme_ns_ids ids; > > @@ -2873,8 +2872,6 @@ static int nvme_init_ns_head(struct nvme_ns *ns, unsigned nsid, > ret = -EINVAL; > goto out_unlock; > } > - > - *new = false; > } > > list_add_tail(&ns->siblings, &head->list); > @@ -2945,7 +2942,6 @@ static void nvme_alloc_ns(struct nvme_ctrl *ctrl, unsigned nsid) > struct nvme_id_ns *id; > char disk_name[DISK_NAME_LEN]; > int node = dev_to_node(ctrl->dev), flags = GENHD_FL_EXT_DEVT; > - bool new = true; > > ns = kzalloc_node(sizeof(*ns), GFP_KERNEL, node); > if (!ns) > @@ -2971,7 +2967,7 @@ static void nvme_alloc_ns(struct nvme_ctrl *ctrl, unsigned nsid) > if (id->ncap == 0) > goto out_free_id; > > - if (nvme_init_ns_head(ns, nsid, id, &new)) > + if (nvme_init_ns_head(ns, nsid, id)) > goto out_free_id; > nvme_setup_streams_ns(ctrl, ns); > > @@ -3037,8 +3033,6 @@ static void nvme_alloc_ns(struct nvme_ctrl *ctrl, unsigned nsid) > pr_warn("%s: failed to register lightnvm sysfs group for identification\n", > ns->disk->disk_name); > > - if (new) > - nvme_mpath_add_disk(ns->head); > nvme_mpath_add_disk_links(ns); > return; > out_unlink_ns: > -- > 2.16.2 >
| |