target: Do memory allocation for bidi commands using target_alloc_sgl

This patch updates transport_generic_new_cmd() to call target_alloc_sgl()
for SGL + page memory allocation for se_cmd->t_bidi_data_sg.

It also adds the special case for SCF_COMPARE_AND_WRITE to calculate a
different bidi_length based upon se_cmd->t_task_nolb.

Reported-by: Christoph Hellwig <hch@lst.de>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Hannes Reinecke <hare@suse.de>
Cc: Martin Petersen <martin.petersen@oracle.com>
Cc: Chris Mason <chris.mason@fusionio.com>
Cc: James Bottomley <JBottomley@Parallels.com>
Cc: Nicholas Bellinger <nab@linux-iscsi.org>
Signed-off-by: Nicholas Bellinger <nab@daterainc.com>

1 files changed, 17 insertions, 0 deletions

diff --git a/drivers/target/target_core_transport.c b/drivers/target/target_core_transport.c
index 607bc3d2bb40..c974e1373c77 100644
--- a/drivers/target/target_core_transport.c
+++ b/drivers/target/target_core_transport.c
@@ -2149,6 +2149,23 @@ transport_generic_new_cmd(struct se_cmd *cmd)
             cmd->data_length) {
                 bool zero_flag = !(cmd->se_cmd_flags & SCF_SCSI_DATA_CDB);
 
+                if ((cmd->se_cmd_flags & SCF_BIDI) ||
+                    (cmd->se_cmd_flags & SCF_COMPARE_AND_WRITE)) {
+                        u32 bidi_length;
+
+                        if (cmd->se_cmd_flags & SCF_COMPARE_AND_WRITE)
+                                bidi_length = cmd->t_task_nolb *
+                                              cmd->se_dev->dev_attrib.block_size;
+                        else
+                                bidi_length = cmd->data_length;
+
+                        ret = target_alloc_sgl(&cmd->t_bidi_data_sg,
+                                               &cmd->t_bidi_data_nents,
+                                               bidi_length, zero_flag);
+                        if (ret < 0)
+                                return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
+                }
+
                 ret = target_alloc_sgl(&cmd->t_data_sg, &cmd->t_data_nents,
                                        cmd->data_length, zero_flag);
                 if (ret < 0)