target: Add protected fabric + unprotected device support

This patch adds a new target_core_fabric_ops callback for allowing fabric
drivers to expose a TPG attribute for signaling when a T10-PI protected
fabric wants to function with an un-protected device without T10-PI.

This specifically is to allow LIO to perform WRITE_STRIP + READ_INSERT
operations when functioning with non T10-PI enabled devices, seperate
from any available hw offloads the fabric supports.

This is done using a new se_sess->sess_prot_type that is set at fabric
session creation time based upon the TPG attribute.  It currently cannot
be changed for individual sessions after initial creation.

Also, update existing target_core_sbc.c code to honor sess_prot_type when
setting up cmd->prot_op + cmd->prot_type assignments.

(Add unlikely and !! boolean conversion in sbc_check_prot - Sagi)

Cc: Martin Petersen <martin.petersen@oracle.com>
Cc: Sagi Grimberg <sagig@mellanox.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Doug Gilbert <dgilbert@interlog.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>

diff --git a/drivers/target/target_core_sbc.c b/drivers/target/target_core_sbc.c
index 95a7a7444965610747a5f009ecb840ed8171e52d..9efd1fd985eef7b928f6af05564568df720324f2 100644 (file)
--- a/drivers/target/target_core_sbc.c
+++ b/drivers/target/target_core_sbc.c
@@ -581,12 +581,13 @@ sbc_compare_and_write(struct se_cmd *cmd)
 }
 
 static int
-sbc_set_prot_op_checks(u8 protect, enum target_prot_type prot_type,
+sbc_set_prot_op_checks(u8 protect, bool fabric_prot, enum target_prot_type prot_type,
                       bool is_write, struct se_cmd *cmd)
 {
        if (is_write) {
-               cmd->prot_op = protect ? TARGET_PROT_DOUT_PASS :
-                                        TARGET_PROT_DOUT_INSERT;
+               cmd->prot_op = fabric_prot ? TARGET_PROT_DOUT_STRIP :
+                              protect ? TARGET_PROT_DOUT_PASS :
+                              TARGET_PROT_DOUT_INSERT;
                switch (protect) {
                case 0x0:
                case 0x3:
@@ -610,8 +611,9 @@ sbc_set_prot_op_checks(u8 protect, enum target_prot_type prot_type,
                        return -EINVAL;
                }
        } else {
-               cmd->prot_op = protect ? TARGET_PROT_DIN_PASS :
-                                        TARGET_PROT_DIN_STRIP;
+               cmd->prot_op = fabric_prot ? TARGET_PROT_DIN_INSERT :
+                              protect ? TARGET_PROT_DIN_PASS :
+                              TARGET_PROT_DIN_STRIP;
                switch (protect) {
                case 0x0:
                case 0x1:
@@ -644,11 +646,15 @@ sbc_check_prot(struct se_device *dev, struct se_cmd *cmd, unsigned char *cdb,
               u32 sectors, bool is_write)
 {
        u8 protect = cdb[1] >> 5;
+       int sp_ops = cmd->se_sess->sup_prot_ops;
+       int pi_prot_type = dev->dev_attrib.pi_prot_type;
+       bool fabric_prot = false;
 
        if (!cmd->t_prot_sg || !cmd->t_prot_nents) {
-               if (protect && !dev->dev_attrib.pi_prot_type) {
-                       pr_err("CDB contains protect bit, but device does not"
-                              " advertise PROTECT=1 feature bit\n");
+               if (unlikely(protect &&
+                   !dev->dev_attrib.pi_prot_type && !cmd->se_sess->sess_prot_type)) {
+                       pr_err("CDB contains protect bit, but device + fabric does"
+                              " not advertise PROTECT=1 feature bit\n");
                        return TCM_INVALID_CDB_FIELD;
                }
                if (cmd->prot_pto)
@@ -669,15 +675,28 @@ sbc_check_prot(struct se_device *dev, struct se_cmd *cmd, unsigned char *cdb,
                cmd->reftag_seed = cmd->t_task_lba;
                break;
        case TARGET_DIF_TYPE0_PROT:
+               /*
+                * See if the fabric supports T10-PI, and the session has been
+                * configured to allow export PROTECT=1 feature bit with backend
+                * devices that don't support T10-PI.
+                */
+               fabric_prot = is_write ?
+                             !!(sp_ops & (TARGET_PROT_DOUT_PASS | TARGET_PROT_DOUT_STRIP)) :
+                             !!(sp_ops & (TARGET_PROT_DIN_PASS | TARGET_PROT_DIN_INSERT));
+
+               if (fabric_prot && cmd->se_sess->sess_prot_type) {
+                       pi_prot_type = cmd->se_sess->sess_prot_type;
+                       break;
+               }
+               /* Fallthrough */
        default:
                return TCM_NO_SENSE;
        }
 
-       if (sbc_set_prot_op_checks(protect, dev->dev_attrib.pi_prot_type,
-                                  is_write, cmd))
+       if (sbc_set_prot_op_checks(protect, fabric_prot, pi_prot_type, is_write, cmd))
                return TCM_INVALID_CDB_FIELD;
 
-       cmd->prot_type = dev->dev_attrib.pi_prot_type;
+       cmd->prot_type = pi_prot_type;
        cmd->prot_length = dev->prot_length * sectors;
 
        /**
@@ -1231,6 +1250,9 @@ sbc_dif_copy_prot(struct se_cmd *cmd, unsigned int sectors, bool read,
        unsigned int i, len, left;
        unsigned int offset = sg_off;
 
+       if (!sg)
+               return;
+
        left = sectors * dev->prot_length;
 
        for_each_sg(cmd->t_prot_sg, psg, cmd->t_prot_nents, i) {

diff --git a/drivers/target/target_core_transport.c b/drivers/target/target_core_transport.c
index 4a00ed5c1880c776354504a90b95c47924f97721..aef989e165ed0adc8ea16087ba952a92e60df157 100644 (file)
--- a/drivers/target/target_core_transport.c
+++ b/drivers/target/target_core_transport.c
@@ -322,10 +322,18 @@ void __transport_register_session(
        struct se_session *se_sess,
        void *fabric_sess_ptr)
 {
+       struct target_core_fabric_ops *tfo = se_tpg->se_tpg_tfo;
        unsigned char buf[PR_REG_ISID_LEN];
 
        se_sess->se_tpg = se_tpg;
        se_sess->fabric_sess_ptr = fabric_sess_ptr;
+       /*
+        * Determine if fabric allows for T10-PI feature bits to be exposed
+        * to initiators for device backends with !dev->dev_attrib.pi_prot_type
+        */
+       if (tfo->tpg_check_prot_fabric_only)
+               se_sess->sess_prot_type = tfo->tpg_check_prot_fabric_only(se_tpg);
+
        /*
         * Used by struct se_node_acl's under ConfigFS to locate active se_session-t
         *

diff --git a/include/target/target_core_base.h b/include/target/target_core_base.h
index 672150b6aaf52bc24c640d16f1f7c841e0be655d..fe25a78fff467d05eda4836580f41310bf416c20 100644 (file)
--- a/include/target/target_core_base.h
+++ b/include/target/target_core_base.h
@@ -616,6 +616,7 @@ struct se_session {
        unsigned                sess_tearing_down:1;
        u64                     sess_bin_isid;
        enum target_prot_op     sup_prot_ops;
+       enum target_prot_type   sess_prot_type;
        struct se_node_acl      *se_node_acl;
        struct se_portal_group *se_tpg;
        void                    *fabric_sess_ptr;

diff --git a/include/target/target_core_fabric.h b/include/target/target_core_fabric.h
index 2f4a2505db4c6ff1ed5f867360191b80c1e7fe0a..c93cfdf0d8e51f54fbf104046d7ef3fb203bb390 100644 (file)
--- a/include/target/target_core_fabric.h
+++ b/include/target/target_core_fabric.h
@@ -27,6 +27,14 @@ struct target_core_fabric_ops {
         * inquiry response
         */
        int (*tpg_check_demo_mode_login_only)(struct se_portal_group *);
+       /*
+        * Optionally used as a configfs tunable to determine when
+        * target-core should signal the PROTECT=1 feature bit for
+        * backends that don't support T10-PI, so that either fabric
+        * HW offload or target-core emulation performs the associated
+        * WRITE_STRIP and READ_INSERT operations.
+        */
+       int (*tpg_check_prot_fabric_only)(struct se_portal_group *);
        struct se_node_acl *(*tpg_alloc_fabric_acl)(
                                        struct se_portal_group *);
        void (*tpg_release_fabric_acl)(struct se_portal_group *,