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>

1 files changed, 100 insertions, 97 deletions

diff --git a/drivers/target/target_core_stat.c b/drivers/target/target_core_stat.c
index 64efee2fba52..ea1287940a7c 100644
--- a/drivers/target/target_core_stat.c
+++ b/drivers/target/target_core_stat.c
@@ -1084,17 +1084,17 @@ static ssize_t target_stat_scsi_auth_intr_show_attr_inst(
         struct se_portal_group *tpg;
         ssize_t ret;
 
-        spin_lock_irq(&nacl->device_list_lock);
-        deve = nacl->device_list[lacl->mapped_lun];
-        if (!deve->se_lun || !deve->se_lun_acl) {
-                spin_unlock_irq(&nacl->device_list_lock);
+        rcu_read_lock();
+        deve = target_nacl_find_deve(nacl, lacl->mapped_lun);
+        if (!deve) {
+                rcu_read_unlock();
                 return -ENODEV;
         }
         tpg = nacl->se_tpg;
         /* scsiInstIndex */
         ret = snprintf(page, PAGE_SIZE, "%u\n",
                         tpg->se_tpg_tfo->tpg_get_inst_index(tpg));
-        spin_unlock_irq(&nacl->device_list_lock);
+        rcu_read_unlock();
         return ret;
 }
 DEV_STAT_SCSI_AUTH_INTR_ATTR_RO(inst);
@@ -1109,16 +1109,16 @@ static ssize_t target_stat_scsi_auth_intr_show_attr_dev(
         struct se_lun *lun;
         ssize_t ret;
 
-        spin_lock_irq(&nacl->device_list_lock);
-        deve = nacl->device_list[lacl->mapped_lun];
-        if (!deve->se_lun || !deve->se_lun_acl) {
-                spin_unlock_irq(&nacl->device_list_lock);
+        rcu_read_lock();
+        deve = target_nacl_find_deve(nacl, lacl->mapped_lun);
+        if (!deve) {
+                rcu_read_unlock();
                 return -ENODEV;
         }
-        lun = deve->se_lun;
+        lun = rcu_dereference(deve->se_lun);
         /* scsiDeviceIndex */
-        ret = snprintf(page, PAGE_SIZE, "%u\n", lun->lun_se_dev->dev_index);
-        spin_unlock_irq(&nacl->device_list_lock);
+        ret = snprintf(page, PAGE_SIZE, "%u\n", lun->lun_index);
+        rcu_read_unlock();
         return ret;
 }
 DEV_STAT_SCSI_AUTH_INTR_ATTR_RO(dev);
@@ -1133,16 +1133,16 @@ static ssize_t target_stat_scsi_auth_intr_show_attr_port(
         struct se_portal_group *tpg;
         ssize_t ret;
 
-        spin_lock_irq(&nacl->device_list_lock);
-        deve = nacl->device_list[lacl->mapped_lun];
-        if (!deve->se_lun || !deve->se_lun_acl) {
-                spin_unlock_irq(&nacl->device_list_lock);
+        rcu_read_lock();
+        deve = target_nacl_find_deve(nacl, lacl->mapped_lun);
+        if (!deve) {
+                rcu_read_unlock();
                 return -ENODEV;
         }
         tpg = nacl->se_tpg;
         /* scsiAuthIntrTgtPortIndex */
         ret = snprintf(page, PAGE_SIZE, "%u\n", tpg->se_tpg_tfo->tpg_get_tag(tpg));
-        spin_unlock_irq(&nacl->device_list_lock);
+        rcu_read_unlock();
         return ret;
 }
 DEV_STAT_SCSI_AUTH_INTR_ATTR_RO(port);
@@ -1156,15 +1156,15 @@ static ssize_t target_stat_scsi_auth_intr_show_attr_indx(
         struct se_dev_entry *deve;
         ssize_t ret;
 
-        spin_lock_irq(&nacl->device_list_lock);
-        deve = nacl->device_list[lacl->mapped_lun];
-        if (!deve->se_lun || !deve->se_lun_acl) {
-                spin_unlock_irq(&nacl->device_list_lock);
+        rcu_read_lock();
+        deve = target_nacl_find_deve(nacl, lacl->mapped_lun);
+        if (!deve) {
+                rcu_read_unlock();
                 return -ENODEV;
         }
         /* scsiAuthIntrIndex */
         ret = snprintf(page, PAGE_SIZE, "%u\n", nacl->acl_index);
-        spin_unlock_irq(&nacl->device_list_lock);
+        rcu_read_unlock();
         return ret;
 }
 DEV_STAT_SCSI_AUTH_INTR_ATTR_RO(indx);
@@ -1178,15 +1178,15 @@ static ssize_t target_stat_scsi_auth_intr_show_attr_dev_or_port(
         struct se_dev_entry *deve;
         ssize_t ret;
 
-        spin_lock_irq(&nacl->device_list_lock);
-        deve = nacl->device_list[lacl->mapped_lun];
-        if (!deve->se_lun || !deve->se_lun_acl) {
-                spin_unlock_irq(&nacl->device_list_lock);
+        rcu_read_lock();
+        deve = target_nacl_find_deve(nacl, lacl->mapped_lun);
+        if (!deve) {
+                rcu_read_unlock();
                 return -ENODEV;
         }
         /* scsiAuthIntrDevOrPort */
         ret = snprintf(page, PAGE_SIZE, "%u\n", 1);
-        spin_unlock_irq(&nacl->device_list_lock);
+        rcu_read_unlock();
         return ret;
 }
 DEV_STAT_SCSI_AUTH_INTR_ATTR_RO(dev_or_port);
@@ -1200,15 +1200,15 @@ static ssize_t target_stat_scsi_auth_intr_show_attr_intr_name(
         struct se_dev_entry *deve;
         ssize_t ret;
 
-        spin_lock_irq(&nacl->device_list_lock);
-        deve = nacl->device_list[lacl->mapped_lun];
-        if (!deve->se_lun || !deve->se_lun_acl) {
-                spin_unlock_irq(&nacl->device_list_lock);
+        rcu_read_lock();
+        deve = target_nacl_find_deve(nacl, lacl->mapped_lun);
+        if (!deve) {
+                rcu_read_unlock();
                 return -ENODEV;
         }
         /* scsiAuthIntrName */
         ret = snprintf(page, PAGE_SIZE, "%s\n", nacl->initiatorname);
-        spin_unlock_irq(&nacl->device_list_lock);
+        rcu_read_unlock();
         return ret;
 }
 DEV_STAT_SCSI_AUTH_INTR_ATTR_RO(intr_name);
@@ -1222,15 +1222,15 @@ static ssize_t target_stat_scsi_auth_intr_show_attr_map_indx(
         struct se_dev_entry *deve;
         ssize_t ret;
 
-        spin_lock_irq(&nacl->device_list_lock);
-        deve = nacl->device_list[lacl->mapped_lun];
-        if (!deve->se_lun || !deve->se_lun_acl) {
-                spin_unlock_irq(&nacl->device_list_lock);
+        rcu_read_lock();
+        deve = target_nacl_find_deve(nacl, lacl->mapped_lun);
+        if (!deve) {
+                rcu_read_unlock();
                 return -ENODEV;
         }
         /* FIXME: scsiAuthIntrLunMapIndex */
         ret = snprintf(page, PAGE_SIZE, "%u\n", 0);
-        spin_unlock_irq(&nacl->device_list_lock);
+        rcu_read_unlock();
         return ret;
 }
 DEV_STAT_SCSI_AUTH_INTR_ATTR_RO(map_indx);
@@ -1244,15 +1244,15 @@ static ssize_t target_stat_scsi_auth_intr_show_attr_att_count(
         struct se_dev_entry *deve;
         ssize_t ret;
 
-        spin_lock_irq(&nacl->device_list_lock);
-        deve = nacl->device_list[lacl->mapped_lun];
-        if (!deve->se_lun || !deve->se_lun_acl) {
-                spin_unlock_irq(&nacl->device_list_lock);
+        rcu_read_lock();
+        deve = target_nacl_find_deve(nacl, lacl->mapped_lun);
+        if (!deve) {
+                rcu_read_unlock();
                 return -ENODEV;
         }
         /* scsiAuthIntrAttachedTimes */
         ret = snprintf(page, PAGE_SIZE, "%u\n", deve->attach_count);
-        spin_unlock_irq(&nacl->device_list_lock);
+        rcu_read_unlock();
         return ret;
 }
 DEV_STAT_SCSI_AUTH_INTR_ATTR_RO(att_count);
@@ -1266,15 +1266,16 @@ static ssize_t target_stat_scsi_auth_intr_show_attr_num_cmds(
         struct se_dev_entry *deve;
         ssize_t ret;
 
-        spin_lock_irq(&nacl->device_list_lock);
-        deve = nacl->device_list[lacl->mapped_lun];
-        if (!deve->se_lun || !deve->se_lun_acl) {
-                spin_unlock_irq(&nacl->device_list_lock);
+        rcu_read_lock();
+        deve = target_nacl_find_deve(nacl, lacl->mapped_lun);
+        if (!deve) {
+                rcu_read_unlock();
                 return -ENODEV;
         }
         /* scsiAuthIntrOutCommands */
-        ret = snprintf(page, PAGE_SIZE, "%u\n", deve->total_cmds);
-        spin_unlock_irq(&nacl->device_list_lock);
+        ret = snprintf(page, PAGE_SIZE, "%lu\n",
+                       atomic_long_read(&deve->total_cmds));
+        rcu_read_unlock();
         return ret;
 }
 DEV_STAT_SCSI_AUTH_INTR_ATTR_RO(num_cmds);
@@ -1288,15 +1289,16 @@ static ssize_t target_stat_scsi_auth_intr_show_attr_read_mbytes(
         struct se_dev_entry *deve;
         ssize_t ret;
 
-        spin_lock_irq(&nacl->device_list_lock);
-        deve = nacl->device_list[lacl->mapped_lun];
-        if (!deve->se_lun || !deve->se_lun_acl) {
-                spin_unlock_irq(&nacl->device_list_lock);
+        rcu_read_lock();
+        deve = target_nacl_find_deve(nacl, lacl->mapped_lun);
+        if (!deve) {
+                rcu_read_unlock();
                 return -ENODEV;
         }
         /* scsiAuthIntrReadMegaBytes */
-        ret = snprintf(page, PAGE_SIZE, "%u\n", (u32)(deve->read_bytes >> 20));
-        spin_unlock_irq(&nacl->device_list_lock);
+        ret = snprintf(page, PAGE_SIZE, "%u\n",
+                      (u32)(atomic_long_read(&deve->read_bytes) >> 20));
+        rcu_read_unlock();
         return ret;
 }
 DEV_STAT_SCSI_AUTH_INTR_ATTR_RO(read_mbytes);
@@ -1310,15 +1312,16 @@ static ssize_t target_stat_scsi_auth_intr_show_attr_write_mbytes(
         struct se_dev_entry *deve;
         ssize_t ret;
 
-        spin_lock_irq(&nacl->device_list_lock);
-        deve = nacl->device_list[lacl->mapped_lun];
-        if (!deve->se_lun || !deve->se_lun_acl) {
-                spin_unlock_irq(&nacl->device_list_lock);
+        rcu_read_lock();
+        deve = target_nacl_find_deve(nacl, lacl->mapped_lun);
+        if (!deve) {
+                rcu_read_unlock();
                 return -ENODEV;
         }
         /* scsiAuthIntrWrittenMegaBytes */
-        ret = snprintf(page, PAGE_SIZE, "%u\n", (u32)(deve->write_bytes >> 20));
-        spin_unlock_irq(&nacl->device_list_lock);
+        ret = snprintf(page, PAGE_SIZE, "%u\n",
+                      (u32)(atomic_long_read(&deve->write_bytes) >> 20));
+        rcu_read_unlock();
         return ret;
 }
 DEV_STAT_SCSI_AUTH_INTR_ATTR_RO(write_mbytes);
@@ -1332,15 +1335,15 @@ static ssize_t target_stat_scsi_auth_intr_show_attr_hs_num_cmds(
         struct se_dev_entry *deve;
         ssize_t ret;
 
-        spin_lock_irq(&nacl->device_list_lock);
-        deve = nacl->device_list[lacl->mapped_lun];
-        if (!deve->se_lun || !deve->se_lun_acl) {
-                spin_unlock_irq(&nacl->device_list_lock);
+        rcu_read_lock();
+        deve = target_nacl_find_deve(nacl, lacl->mapped_lun);
+        if (!deve) {
+                rcu_read_unlock();
                 return -ENODEV;
         }
         /* FIXME: scsiAuthIntrHSOutCommands */
         ret = snprintf(page, PAGE_SIZE, "%u\n", 0);
-        spin_unlock_irq(&nacl->device_list_lock);
+        rcu_read_unlock();
         return ret;
 }
 DEV_STAT_SCSI_AUTH_INTR_ATTR_RO(hs_num_cmds);
@@ -1354,16 +1357,16 @@ static ssize_t target_stat_scsi_auth_intr_show_attr_creation_time(
         struct se_dev_entry *deve;
         ssize_t ret;
 
-        spin_lock_irq(&nacl->device_list_lock);
-        deve = nacl->device_list[lacl->mapped_lun];
-        if (!deve->se_lun || !deve->se_lun_acl) {
-                spin_unlock_irq(&nacl->device_list_lock);
+        rcu_read_lock();
+        deve = target_nacl_find_deve(nacl, lacl->mapped_lun);
+        if (!deve) {
+                rcu_read_unlock();
                 return -ENODEV;
         }
         /* scsiAuthIntrLastCreation */
         ret = snprintf(page, PAGE_SIZE, "%u\n", (u32)(((u32)deve->creation_time -
                                 INITIAL_JIFFIES) * 100 / HZ));
-        spin_unlock_irq(&nacl->device_list_lock);
+        rcu_read_unlock();
         return ret;
 }
 DEV_STAT_SCSI_AUTH_INTR_ATTR_RO(creation_time);
@@ -1377,15 +1380,15 @@ static ssize_t target_stat_scsi_auth_intr_show_attr_row_status(
         struct se_dev_entry *deve;
         ssize_t ret;
 
-        spin_lock_irq(&nacl->device_list_lock);
-        deve = nacl->device_list[lacl->mapped_lun];
-        if (!deve->se_lun || !deve->se_lun_acl) {
-                spin_unlock_irq(&nacl->device_list_lock);
+        rcu_read_lock();
+        deve = target_nacl_find_deve(nacl, lacl->mapped_lun);
+        if (!deve) {
+                rcu_read_unlock();
                 return -ENODEV;
         }
         /* FIXME: scsiAuthIntrRowStatus */
         ret = snprintf(page, PAGE_SIZE, "Ready\n");
-        spin_unlock_irq(&nacl->device_list_lock);
+        rcu_read_unlock();
         return ret;
 }
 DEV_STAT_SCSI_AUTH_INTR_ATTR_RO(row_status);
@@ -1450,17 +1453,17 @@ static ssize_t target_stat_scsi_att_intr_port_show_attr_inst(
         struct se_portal_group *tpg;
         ssize_t ret;
 
-        spin_lock_irq(&nacl->device_list_lock);
-        deve = nacl->device_list[lacl->mapped_lun];
-        if (!deve->se_lun || !deve->se_lun_acl) {
-                spin_unlock_irq(&nacl->device_list_lock);
+        rcu_read_lock();
+        deve = target_nacl_find_deve(nacl, lacl->mapped_lun);
+        if (!deve) {
+                rcu_read_unlock();
                 return -ENODEV;
         }
         tpg = nacl->se_tpg;
         /* scsiInstIndex */
         ret = snprintf(page, PAGE_SIZE, "%u\n",
                         tpg->se_tpg_tfo->tpg_get_inst_index(tpg));
-        spin_unlock_irq(&nacl->device_list_lock);
+        rcu_read_unlock();
         return ret;
 }
 DEV_STAT_SCSI_ATTR_INTR_PORT_ATTR_RO(inst);
@@ -1475,16 +1478,16 @@ static ssize_t target_stat_scsi_att_intr_port_show_attr_dev(
         struct se_lun *lun;
         ssize_t ret;
 
-        spin_lock_irq(&nacl->device_list_lock);
-        deve = nacl->device_list[lacl->mapped_lun];
-        if (!deve->se_lun || !deve->se_lun_acl) {
-                spin_unlock_irq(&nacl->device_list_lock);
+        rcu_read_lock();
+        deve = target_nacl_find_deve(nacl, lacl->mapped_lun);
+        if (!deve) {
+                rcu_read_unlock();
                 return -ENODEV;
         }
-        lun = deve->se_lun;
+        lun = rcu_dereference(deve->se_lun);
         /* scsiDeviceIndex */
-        ret = snprintf(page, PAGE_SIZE, "%u\n", lun->lun_se_dev->dev_index);
-        spin_unlock_irq(&nacl->device_list_lock);
+        ret = snprintf(page, PAGE_SIZE, "%u\n", lun->lun_index);
+        rcu_read_unlock();
         return ret;
 }
 DEV_STAT_SCSI_ATTR_INTR_PORT_ATTR_RO(dev);
@@ -1499,16 +1502,16 @@ static ssize_t target_stat_scsi_att_intr_port_show_attr_port(
         struct se_portal_group *tpg;
         ssize_t ret;
 
-        spin_lock_irq(&nacl->device_list_lock);
-        deve = nacl->device_list[lacl->mapped_lun];
-        if (!deve->se_lun || !deve->se_lun_acl) {
-                spin_unlock_irq(&nacl->device_list_lock);
+        rcu_read_lock();
+        deve = target_nacl_find_deve(nacl, lacl->mapped_lun);
+        if (!deve) {
+                rcu_read_unlock();
                 return -ENODEV;
         }
         tpg = nacl->se_tpg;
         /* scsiPortIndex */
         ret = snprintf(page, PAGE_SIZE, "%u\n", tpg->se_tpg_tfo->tpg_get_tag(tpg));
-        spin_unlock_irq(&nacl->device_list_lock);
+        rcu_read_unlock();
         return ret;
 }
 DEV_STAT_SCSI_ATTR_INTR_PORT_ATTR_RO(port);
@@ -1548,15 +1551,15 @@ static ssize_t target_stat_scsi_att_intr_port_show_attr_port_auth_indx(
         struct se_dev_entry *deve;
         ssize_t ret;
 
-        spin_lock_irq(&nacl->device_list_lock);
-        deve = nacl->device_list[lacl->mapped_lun];
-        if (!deve->se_lun || !deve->se_lun_acl) {
-                spin_unlock_irq(&nacl->device_list_lock);
+        rcu_read_lock();
+        deve = target_nacl_find_deve(nacl, lacl->mapped_lun);
+        if (!deve) {
+                rcu_read_unlock();
                 return -ENODEV;
         }
         /* scsiAttIntrPortAuthIntrIdx */
         ret = snprintf(page, PAGE_SIZE, "%u\n", nacl->acl_index);
-        spin_unlock_irq(&nacl->device_list_lock);
+        rcu_read_unlock();
         return ret;
 }
 DEV_STAT_SCSI_ATTR_INTR_PORT_ATTR_RO(port_auth_indx);