target: Add transport_cmd_check_stop write_pending bit

This patch adds a new transport_cmd_check_stop() parameter for signaling
when TRANSPORT_WRITE_PENDING needs to be set.

This allows transport_generic_new_cmd() to avoid the extra lock acquire/release
of ->t_state_lock in the fast path for DMA_TO_DEVICE operations ahead of
transport_cmd_check_stop() + se_tfo->write_pending().

Cc: Christoph Hellwig <hch@lst.de>
Cc: Roland Dreier <roland@kernel.org>
Cc: Kent Overstreet <koverstreet@google.com>
Cc: Or Gerlitz <ogerlitz@mellanox.com>
Cc: Moussa Ba <moussaba@micron.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>

diff --git a/drivers/target/target_core_transport.c b/drivers/target/target_core_transport.c
index 21e3158..39319ef 100644 (file)
--- a/drivers/target/target_core_transport.c
+++ b/drivers/target/target_core_transport.c
@@ -446,11 +446,15 @@ static void target_remove_from_state_list(struct se_cmd *cmd)
        spin_unlock_irqrestore(&dev->execute_task_lock, flags);
 }
 
-static int transport_cmd_check_stop(struct se_cmd *cmd, bool remove_from_lists)
+static int transport_cmd_check_stop(struct se_cmd *cmd, bool remove_from_lists,
+                                   bool write_pending)
 {
        unsigned long flags;
 
        spin_lock_irqsave(&cmd->t_state_lock, flags);
+       if (write_pending)
+               cmd->t_state = TRANSPORT_WRITE_PENDING;
+
        /*
         * Determine if IOCTL context caller in requesting the stopping of this
         * command for LUN shutdown purposes.
@@ -515,7 +519,7 @@ static int transport_cmd_check_stop(struct se_cmd *cmd, bool remove_from_lists)
 
 static int transport_cmd_check_stop_to_fabric(struct se_cmd *cmd)
 {
-       return transport_cmd_check_stop(cmd, true);
+       return transport_cmd_check_stop(cmd, true, false);
 }
 
 static void transport_lun_remove_cmd(struct se_cmd *cmd)
@@ -2116,12 +2120,7 @@ transport_generic_new_cmd(struct se_cmd *cmd)
                target_execute_cmd(cmd);
                return 0;
        }
-
-       spin_lock_irq(&cmd->t_state_lock);
-       cmd->t_state = TRANSPORT_WRITE_PENDING;
-       spin_unlock_irq(&cmd->t_state_lock);
-
-       transport_cmd_check_stop(cmd, false);
+       transport_cmd_check_stop(cmd, false, true);
 
        ret = cmd->se_tfo->write_pending(cmd);
        if (ret == -EAGAIN || ret == -ENOMEM)
@@ -2319,7 +2318,7 @@ static int transport_lun_wait_for_tasks(struct se_cmd *cmd, struct se_lun *lun)
                pr_debug("ConfigFS ITT[0x%08x] - CMD_T_STOP, skipping\n",
                         cmd->se_tfo->get_task_tag(cmd));
                spin_unlock_irqrestore(&cmd->t_state_lock, flags);
-               transport_cmd_check_stop(cmd, false);
+               transport_cmd_check_stop(cmd, false, false);
                return -EPERM;
        }
        cmd->transport_state |= CMD_T_LUN_FE_STOP;
@@ -2427,7 +2426,7 @@ check_cond:
 
                        spin_unlock_irqrestore(&cmd->t_state_lock,
                                        cmd_flags);
-                       transport_cmd_check_stop(cmd, false);
+                       transport_cmd_check_stop(cmd, false, false);
                        complete(&cmd->transport_lun_fe_stop_comp);
                        spin_lock_irqsave(&lun->lun_cmd_lock, lun_flags);
                        continue;