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authorBaegjae Sung <baegjae@gmail.com>2018-02-28 16:06:04 +0900
committerKeith Busch <keith.busch@intel.com>2018-02-28 02:46:48 -0700
commit9bd82b1a4418d9b7db000bf557ed608f2872b7c9 (patch)
tree357d0433ac48f7970204567569d55d09cec94d5e
parentf25a2dfc20e3a3ed8fe6618c331799dd7bd01190 (diff)
nvme-multipath: fix sysfs dangerously created links
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 nvme_mpath_add_disk (for creating head namespace) is called just before the nvme_mpath_add_disk_links (for creating private namespaces). In nvme_mpath_add_disk, the first context acquires the lock of subsystem and creates a head namespace, and other contexts do nothing by checking GENHD_FL_UP of a head namespace after waiting to acquire the lock. We verified the code with or without multipathing using three vendors of dual-port NVMe SSDs. Signed-off-by: Baegjae Sung <baegjae@gmail.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Keith Busch <keith.busch@intel.com>
-rw-r--r--drivers/nvme/host/core.c12
-rw-r--r--drivers/nvme/host/multipath.c15
2 files changed, 13 insertions, 14 deletions
diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index f431c32774f3..6088ea13a6bf 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -2835,7 +2835,7 @@ out:
}
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);
@@ -2851,8 +2851,6 @@ static int nvme_init_ns_head(struct nvme_ns *ns, unsigned nsid,
ret = PTR_ERR(head);
goto out_unlock;
}
-
- *new = true;
} else {
struct nvme_ns_ids ids;
@@ -2864,8 +2862,6 @@ 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);
@@ -2936,7 +2932,6 @@ 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)
@@ -2962,7 +2957,7 @@ 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);
@@ -3028,8 +3023,7 @@ 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(ns->head);
nvme_mpath_add_disk_links(ns);
return;
out_unlink_ns:
diff --git a/drivers/nvme/host/multipath.c b/drivers/nvme/host/multipath.c
index 3b211d9e58b8..b7e5c6db4d92 100644
--- a/drivers/nvme/host/multipath.c
+++ b/drivers/nvme/host/multipath.c
@@ -198,11 +198,16 @@ void nvme_mpath_add_disk(struct nvme_ns_head *head)
{
if (!head->disk)
return;
- device_add_disk(&head->subsys->dev, head->disk);
- if (sysfs_create_group(&disk_to_dev(head->disk)->kobj,
- &nvme_ns_id_attr_group))
- pr_warn("%s: failed to create sysfs group for identification\n",
- head->disk->disk_name);
+
+ mutex_lock(&head->subsys->lock);
+ if (!(head->disk->flags & GENHD_FL_UP)) {
+ device_add_disk(&head->subsys->dev, head->disk);
+ if (sysfs_create_group(&disk_to_dev(head->disk)->kobj,
+ &nvme_ns_id_attr_group))
+ pr_warn("%s: failed to create sysfs group for identification\n",
+ head->disk->disk_name);
+ }
+ mutex_unlock(&head->subsys->lock);
}
void nvme_mpath_add_disk_links(struct nvme_ns *ns)