target: Convert se_node_acl->device_list[] to RCU hlist
This patch converts se_node_acl->device_list[] table for mappedluns
to modern RCU hlist_head usage in order to support an arbitrary number
of node_acl lun mappings.
It converts transport_lookup_*_lun() fast-path code to use RCU read path
primitives when looking up se_dev_entry. It adds a new hlist_head at
se_node_acl->lun_entry_hlist for this purpose.
For transport_lookup_cmd_lun() code, it works with existing per-cpu
se_lun->lun_ref when associating se_cmd with se_lun + se_device.
Also, go ahead and update core_create_device_list_for_node() +
core_free_device_list_for_node() to use ->lun_entry_hlist.
It also converts se_dev_entry->pr_ref_count access to use modern
struct kref counting, and updates core_disable_device_list_for_node()
to kref_put() and block on se_deve->pr_comp waiting for outstanding PR
special-case PR references to drop, then invoke kfree_rcu() to wait
for the RCU grace period to complete before releasing memory.
So now that se_node_acl->lun_entry_hlist fast path access uses RCU
protected pointers, go ahead and convert remaining non-fast path
RCU updater code using ->lun_entry_lock to struct mutex to allow
callers to block while walking se_node_acl->lun_entry_hlist.
Finally drop the left-over core_clear_initiator_node_from_tpg() that
originally cleared lun_access during se_node_acl shutdown, as post
RCU conversion it now becomes duplicated logic.
Reviewed-by: Hannes Reinecke <hare@suse.de>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Sagi Grimberg <sagig@mellanox.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
diff --git a/drivers/target/target_core_ua.c b/drivers/target/target_core_ua.c
index a0bf0d1..6c9616d 100644
--- a/drivers/target/target_core_ua.c
+++ b/drivers/target/target_core_ua.c
@@ -50,9 +50,17 @@
if (!nacl)
return 0;
- deve = nacl->device_list[cmd->orig_fe_lun];
- if (!atomic_read(&deve->ua_count))
+ rcu_read_lock();
+ deve = target_nacl_find_deve(nacl, cmd->orig_fe_lun);
+ if (!deve) {
+ rcu_read_unlock();
return 0;
+ }
+ if (!atomic_read(&deve->ua_count)) {
+ rcu_read_unlock();
+ return 0;
+ }
+ rcu_read_unlock();
/*
* From sam4r14, section 5.14 Unit attention condition:
*
@@ -103,9 +111,12 @@
ua->ua_asc = asc;
ua->ua_ascq = ascq;
- spin_lock_irq(&nacl->device_list_lock);
- deve = nacl->device_list[unpacked_lun];
-
+ rcu_read_lock();
+ deve = target_nacl_find_deve(nacl, unpacked_lun);
+ if (!deve) {
+ rcu_read_unlock();
+ return -EINVAL;
+ }
spin_lock(&deve->ua_lock);
list_for_each_entry_safe(ua_p, ua_tmp, &deve->ua_list, ua_nacl_list) {
/*
@@ -113,7 +124,7 @@
*/
if ((ua_p->ua_asc == asc) && (ua_p->ua_ascq == ascq)) {
spin_unlock(&deve->ua_lock);
- spin_unlock_irq(&nacl->device_list_lock);
+ rcu_read_unlock();
kmem_cache_free(se_ua_cache, ua);
return 0;
}
@@ -158,14 +169,13 @@
list_add_tail(&ua->ua_nacl_list,
&deve->ua_list);
spin_unlock(&deve->ua_lock);
- spin_unlock_irq(&nacl->device_list_lock);
atomic_inc_mb(&deve->ua_count);
+ rcu_read_unlock();
return 0;
}
list_add_tail(&ua->ua_nacl_list, &deve->ua_list);
spin_unlock(&deve->ua_lock);
- spin_unlock_irq(&nacl->device_list_lock);
pr_debug("[%s]: Allocated UNIT ATTENTION, mapped LUN: %u, ASC:"
" 0x%02x, ASCQ: 0x%02x\n",
@@ -173,6 +183,7 @@
asc, ascq);
atomic_inc_mb(&deve->ua_count);
+ rcu_read_unlock();
return 0;
}
@@ -210,10 +221,14 @@
if (!nacl)
return;
- spin_lock_irq(&nacl->device_list_lock);
- deve = nacl->device_list[cmd->orig_fe_lun];
+ rcu_read_lock();
+ deve = target_nacl_find_deve(nacl, cmd->orig_fe_lun);
+ if (!deve) {
+ rcu_read_unlock();
+ return;
+ }
if (!atomic_read(&deve->ua_count)) {
- spin_unlock_irq(&nacl->device_list_lock);
+ rcu_read_unlock();
return;
}
/*
@@ -249,7 +264,7 @@
atomic_dec_mb(&deve->ua_count);
}
spin_unlock(&deve->ua_lock);
- spin_unlock_irq(&nacl->device_list_lock);
+ rcu_read_unlock();
pr_debug("[%s]: %s UNIT ATTENTION condition with"
" INTLCK_CTRL: %d, mapped LUN: %u, got CDB: 0x%02x"
@@ -278,10 +293,14 @@
if (!nacl)
return -EINVAL;
- spin_lock_irq(&nacl->device_list_lock);
- deve = nacl->device_list[cmd->orig_fe_lun];
+ rcu_read_lock();
+ deve = target_nacl_find_deve(nacl, cmd->orig_fe_lun);
+ if (!deve) {
+ rcu_read_unlock();
+ return -EINVAL;
+ }
if (!atomic_read(&deve->ua_count)) {
- spin_unlock_irq(&nacl->device_list_lock);
+ rcu_read_unlock();
return -EPERM;
}
/*
@@ -307,7 +326,7 @@
atomic_dec_mb(&deve->ua_count);
}
spin_unlock(&deve->ua_lock);
- spin_unlock_irq(&nacl->device_list_lock);
+ rcu_read_unlock();
pr_debug("[%s]: Released UNIT ATTENTION condition, mapped"
" LUN: %u, got REQUEST_SENSE reported ASC: 0x%02x,"
