From: Nicholas Bellinger <n...@linux-iscsi.org>

This patch adds lib/tag.c based transport_init_session_tagpool() logic
that allows fabric drivers to setup a per-cpu se_sess->sess_tag_pool
and associated se_sess->sess_cmd_map for basic tagged pre-allocation
of fabric descriptor sized memory.

Cc: Kent Overstreet <koverstr...@google.com>
Cc: Roland Dreier <rol...@kernel.org>
Cc: Christoph Hellwig <h...@lst.de>
Cc: Asias He <as...@redhat.com>
Cc: Michael S. Tsirkin <m...@redhat.com>
Cc: Or Gerlitz <ogerl...@mellanox.com>
Cc: Moussa Ba <mouss...@micron.com>
Signed-off-by: Nicholas Bellinger <n...@linux-iscsi.org>
---
 drivers/target/target_core_transport.c |   33 ++++++++++++++++++++++++++++++++
 include/target/target_core_base.h      |    5 ++++
 include/target/target_core_fabric.h    |    1 +
 3 files changed, 39 insertions(+), 0 deletions(-)

diff --git a/drivers/target/target_core_transport.c 
b/drivers/target/target_core_transport.c
index abb7e40..4715f97 100644
--- a/drivers/target/target_core_transport.c
+++ b/drivers/target/target_core_transport.c
@@ -228,6 +228,35 @@ struct se_session *transport_init_session(void)
 }
 EXPORT_SYMBOL(transport_init_session);
 
+struct se_session *transport_init_session_tagpool(unsigned int tag_num,
+                                                 unsigned int tag_size)
+{
+       struct se_session *se_sess;
+       int rc;
+
+       se_sess = transport_init_session();
+       if (IS_ERR(se_sess))
+               return se_sess;
+
+       se_sess->sess_cmd_map = kzalloc(tag_num * tag_size, GFP_KERNEL);
+       if (!se_sess->sess_cmd_map) {
+               pr_err("Unable to allocate se_sess->sess_cmd_map\n");
+               transport_free_session(se_sess);
+               return ERR_PTR(-ENOMEM);
+       }
+
+       rc = tag_pool_init(&se_sess->sess_tag_pool, tag_num);
+       if (rc < 0) {
+               pr_err("Unable to init se_sess->sess_tag_pool,"
+                       " tag_num: %u\n", tag_num);
+               transport_free_session(se_sess);
+               return ERR_PTR(-ENOMEM);
+       }
+
+       return se_sess;
+}
+EXPORT_SYMBOL(transport_init_session_tagpool);
+
 /*
  * Called with spin_lock_irqsave(&struct se_portal_group->session_lock called.
  */
@@ -363,6 +392,10 @@ EXPORT_SYMBOL(transport_deregister_session_configfs);
 
 void transport_free_session(struct se_session *se_sess)
 {
+       if (se_sess->sess_cmd_map) {
+               tag_pool_free(&se_sess->sess_tag_pool);
+               kfree(se_sess->sess_cmd_map);
+       }
        kmem_cache_free(se_sess_cache, se_sess);
 }
 EXPORT_SYMBOL(transport_free_session);
diff --git a/include/target/target_core_base.h 
b/include/target/target_core_base.h
index a5c97db..8afd995 100644
--- a/include/target/target_core_base.h
+++ b/include/target/target_core_base.h
@@ -5,6 +5,7 @@
 #include <linux/configfs.h>
 #include <linux/dma-mapping.h>
 #include <linux/blkdev.h>
+#include <linux/tags.h>
 #include <scsi/scsi_cmnd.h>
 #include <net/sock.h>
 #include <net/tcp.h>
@@ -422,6 +423,8 @@ struct se_cmd {
        enum dma_data_direction data_direction;
        /* For SAM Task Attribute */
        int                     sam_task_attr;
+       /* Used for se_sess->sess_tag_pool */
+       unsigned int            map_tag;
        /* Transport protocol dependent state, see transport_state_table */
        enum transport_state_table t_state;
        unsigned                cmd_wait_set:1;
@@ -542,6 +545,8 @@ struct se_session {
        struct list_head        sess_cmd_list;
        spinlock_t              sess_cmd_lock;
        struct kref             sess_kref;
+       void                    *sess_cmd_map;
+       struct tag_pool         sess_tag_pool;
 };
 
 struct se_device;
diff --git a/include/target/target_core_fabric.h 
b/include/target/target_core_fabric.h
index ba3471b..318520b 100644
--- a/include/target/target_core_fabric.h
+++ b/include/target/target_core_fabric.h
@@ -84,6 +84,7 @@ struct target_core_fabric_ops {
 };
 
 struct se_session *transport_init_session(void);
+struct se_session *transport_init_session_tagpool(unsigned int, unsigned int);
 void   __transport_register_session(struct se_portal_group *,
                struct se_node_acl *, struct se_session *, void *);
 void   transport_register_session(struct se_portal_group *,
-- 
1.7.2.5

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