target: Report correct response length for some commands

When an initiator sends an allocation length bigger than what its
command consumes, the target should only return the actual response data
and set the residual length to the unused part of the allocation length.

Add a helper function that command handlers (INQUIRY, READ CAPACITY,
etc) can use to do this correctly, and use this code to get the correct
residual for commands that don't use the full initiator allocation in the
handlers for READ CAPACITY, READ CAPACITY(16), INQUIRY, MODE SENSE and
REPORT LUNS.

This addresses a handful of failures as reported by Christophe with
the Windows Certification Kit:

  http://permalink.gmane.org/gmane.linux.scsi.target.devel/6515

Signed-off-by: Roland Dreier <roland@purestorage.com>
Tested-by: Christophe Vu-Brugier <cvubrugier@yahoo.fr>
Cc: stable@vger.kernel.org # 3.10+
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 97a33603795d1577e06376792d17f6cb017af4e9..1d3a626bf24fc71a8c175d7a4164c3dbac7e5528 100644 (file)
--- a/drivers/target/target_core_sbc.c
+++ b/drivers/target/target_core_sbc.c
@@ -81,7 +81,7 @@ sbc_emulate_readcapacity(struct se_cmd *cmd)
                transport_kunmap_data_sg(cmd);
        }
 
-       target_complete_cmd(cmd, GOOD);
+       target_complete_cmd_with_length(cmd, GOOD, 8);
        return 0;
 }
 
@@ -137,7 +137,7 @@ sbc_emulate_readcapacity_16(struct se_cmd *cmd)
                transport_kunmap_data_sg(cmd);
        }
 
-       target_complete_cmd(cmd, GOOD);
+       target_complete_cmd_with_length(cmd, GOOD, 32);
        return 0;
 }
 

diff --git a/drivers/target/target_core_spc.c b/drivers/target/target_core_spc.c
index 17b5b7e099fa2d80083e9c3f2261cae0cf2bc8aa..6cd7222738fc4697f8c1be7c337ef7418fd09075 100644 (file)
--- a/drivers/target/target_core_spc.c
+++ b/drivers/target/target_core_spc.c
@@ -716,6 +716,7 @@ spc_emulate_inquiry(struct se_cmd *cmd)
        unsigned char *buf;
        sense_reason_t ret;
        int p;
+       int len = 0;
 
        buf = kzalloc(SE_INQUIRY_BUF, GFP_KERNEL);
        if (!buf) {
@@ -737,6 +738,7 @@ spc_emulate_inquiry(struct se_cmd *cmd)
                }
 
                ret = spc_emulate_inquiry_std(cmd, buf);
+               len = buf[4] + 5;
                goto out;
        }
 
@@ -744,6 +746,7 @@ spc_emulate_inquiry(struct se_cmd *cmd)
                if (cdb[2] == evpd_handlers[p].page) {
                        buf[1] = cdb[2];
                        ret = evpd_handlers[p].emulate(cmd, buf);
+                       len = get_unaligned_be16(&buf[2]) + 4;
                        goto out;
                }
        }
@@ -760,7 +763,7 @@ out:
        kfree(buf);
 
        if (!ret)
-               target_complete_cmd(cmd, GOOD);
+               target_complete_cmd_with_length(cmd, GOOD, len);
        return ret;
 }
 
@@ -1098,7 +1101,7 @@ set_length:
                transport_kunmap_data_sg(cmd);
        }
 
-       target_complete_cmd(cmd, GOOD);
+       target_complete_cmd_with_length(cmd, GOOD, length);
        return 0;
 }
 
@@ -1274,7 +1277,7 @@ done:
        buf[3] = (lun_count & 0xff);
        transport_kunmap_data_sg(cmd);
 
-       target_complete_cmd(cmd, GOOD);
+       target_complete_cmd_with_length(cmd, GOOD, 8 + lun_count * 8);
        return 0;
 }
 EXPORT_SYMBOL(spc_emulate_report_luns);

diff --git a/drivers/target/target_core_transport.c b/drivers/target/target_core_transport.c
index 15dbf6e972895e3f32f0b586450036103b7bb11b..c9e8b35a954f3a72d9c35793526e7bceb02fd090 100644 (file)
--- a/drivers/target/target_core_transport.c
+++ b/drivers/target/target_core_transport.c
@@ -703,6 +703,23 @@ void target_complete_cmd(struct se_cmd *cmd, u8 scsi_status)
 }
 EXPORT_SYMBOL(target_complete_cmd);
 
+void target_complete_cmd_with_length(struct se_cmd *cmd, u8 scsi_status, int length)
+{
+       if (scsi_status == SAM_STAT_GOOD && length < cmd->data_length) {
+               if (cmd->se_cmd_flags & SCF_UNDERFLOW_BIT) {
+                       cmd->residual_count += cmd->data_length - length;
+               } else {
+                       cmd->se_cmd_flags |= SCF_UNDERFLOW_BIT;
+                       cmd->residual_count = cmd->data_length - length;
+               }
+
+               cmd->data_length = length;
+       }
+
+       target_complete_cmd(cmd, scsi_status);
+}
+EXPORT_SYMBOL(target_complete_cmd_with_length);
+
 static void target_add_to_state_list(struct se_cmd *cmd)
 {
        struct se_device *dev = cmd->se_dev;

diff --git a/include/target/target_core_backend.h b/include/target/target_core_backend.h
index 3a1c1eea1fffcaee767d4bef1a8ea2700f1884e2..9adc1bca1178ba36482f63bf8cef1444045f7709 100644 (file)
--- a/include/target/target_core_backend.h
+++ b/include/target/target_core_backend.h
@@ -59,6 +59,7 @@ int   transport_subsystem_register(struct se_subsystem_api *);
 void   transport_subsystem_release(struct se_subsystem_api *);
 
 void   target_complete_cmd(struct se_cmd *, u8);
+void   target_complete_cmd_with_length(struct se_cmd *, u8, int);
 
 sense_reason_t spc_parse_cdb(struct se_cmd *cmd, unsigned int *size);
 sense_reason_t spc_emulate_report_luns(struct se_cmd *cmd);