target: Make TCM_WRITE_PROTECT failure honor D_SENSE bit

This patch changes transport_lookup_cmd_lun() to obtain
se_lun->lun_ref + se_cmd->se_device rcu_dereference during
TCM_WRITE_PROTECT -> CHECK_CONDITION failure status.

Do this to ensure the active control D_SENSE mode page bit
is being honored.

Reported-by: Sagi Grimberg <sagig@mellanox.com>
Reviewed-by: Sagi Grimberg <sagig@mellanox.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>

1 files changed, 23 insertions, 17 deletions

diff --git a/drivers/target/target_core_device.c b/drivers/target/target_core_device.c
index abf20763b0b6..88ea4e4f124b 100644
--- a/drivers/target/target_core_device.c
+++ b/drivers/target/target_core_device.c
@@ -62,22 +62,13 @@ transport_lookup_cmd_lun(struct se_cmd *se_cmd, u64 unpacked_lun)
         struct se_session *se_sess = se_cmd->se_sess;
         struct se_node_acl *nacl = se_sess->se_node_acl;
         struct se_dev_entry *deve;
+        sense_reason_t ret = TCM_NO_SENSE;
 
         rcu_read_lock();
         deve = target_nacl_find_deve(nacl, unpacked_lun);
         if (deve) {
                 atomic_long_inc(&deve->total_cmds);
 
-                if ((se_cmd->data_direction == DMA_TO_DEVICE) &&
-                    (deve->lun_flags & TRANSPORT_LUNFLAGS_READ_ONLY)) {
-                        pr_err("TARGET_CORE[%s]: Detected WRITE_PROTECTED LUN"
-                                " Access for 0x%08llx\n",
-                                se_cmd->se_tfo->get_fabric_name(),
-                                unpacked_lun);
-                        rcu_read_unlock();
-                        return TCM_WRITE_PROTECTED;
-                }
-
                 if (se_cmd->data_direction == DMA_TO_DEVICE)
                         atomic_long_add(se_cmd->data_length,
                                         &deve->write_bytes);
@@ -93,6 +84,17 @@ transport_lookup_cmd_lun(struct se_cmd *se_cmd, u64 unpacked_lun)
 
                 percpu_ref_get(&se_lun->lun_ref);
                 se_cmd->lun_ref_active = true;
+
+                if ((se_cmd->data_direction == DMA_TO_DEVICE) &&
+                    (deve->lun_flags & TRANSPORT_LUNFLAGS_READ_ONLY)) {
+                        pr_err("TARGET_CORE[%s]: Detected WRITE_PROTECTED LUN"
+                                " Access for 0x%08llx\n",
+                                se_cmd->se_tfo->get_fabric_name(),
+                                unpacked_lun);
+                        rcu_read_unlock();
+                        ret = TCM_WRITE_PROTECTED;
+                        goto ref_dev;
+                }
         }
         rcu_read_unlock();
 
@@ -109,12 +111,6 @@ transport_lookup_cmd_lun(struct se_cmd *se_cmd, u64 unpacked_lun)
                                 unpacked_lun);
                         return TCM_NON_EXISTENT_LUN;
                 }
-                /*
-                 * Force WRITE PROTECT for virtual LUN 0
-                 */
-                if ((se_cmd->data_direction != DMA_FROM_DEVICE) &&
-                    (se_cmd->data_direction != DMA_NONE))
-                        return TCM_WRITE_PROTECTED;
 
                 se_lun = se_sess->se_tpg->tpg_virt_lun0;
                 se_cmd->se_lun = se_sess->se_tpg->tpg_virt_lun0;
@@ -123,6 +119,15 @@ transport_lookup_cmd_lun(struct se_cmd *se_cmd, u64 unpacked_lun)
 
                 percpu_ref_get(&se_lun->lun_ref);
                 se_cmd->lun_ref_active = true;
+
+                /*
+                 * Force WRITE PROTECT for virtual LUN 0
+                 */
+                if ((se_cmd->data_direction != DMA_FROM_DEVICE) &&
+                    (se_cmd->data_direction != DMA_NONE)) {
+                        ret = TCM_WRITE_PROTECTED;
+                        goto ref_dev;
+                }
         }
         /*
          * RCU reference protected by percpu se_lun->lun_ref taken above that
@@ -130,6 +135,7 @@ transport_lookup_cmd_lun(struct se_cmd *se_cmd, u64 unpacked_lun)
          * pointer can be kfree_rcu() by the final se_lun->lun_group put via
          * target_core_fabric_configfs.c:target_fabric_port_release
          */
+ref_dev:
         se_cmd->se_dev = rcu_dereference_raw(se_lun->lun_se_dev);
         atomic_long_inc(&se_cmd->se_dev->num_cmds);
 
@@ -140,7 +146,7 @@ transport_lookup_cmd_lun(struct se_cmd *se_cmd, u64 unpacked_lun)
                 atomic_long_add(se_cmd->data_length,
                                 &se_cmd->se_dev->read_bytes);
 
-        return 0;
+        return ret;
 }
 EXPORT_SYMBOL(transport_lookup_cmd_lun);