target: Make all control CDBs scatter-gather
Previously, some control CDBs did not allocate memory in pages for their
data buffer, but just did a kmalloc. This patch makes all cdbs allocate
pages.
This has the benefit of streamlining some paths that had to behave
differently when we used two allocation methods. The downside is that
all accesses to the data buffer need to kmap it before use, and need to
handle data in page-sized chunks if more than a page is needed for a given
command's data buffer.
Finally, note that cdbs with no data buffers are handled a little
differently. Before, SCSI_NON_DATA_CDBs would not call get_mem at all
(they'd be in the final else in transport_allocate_resources) but now
these will make it into generic_get_mem, but just not allocate any
buffers.
Signed-off-by: Andy Grover <agrover@redhat.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
diff --git a/drivers/target/target_core_device.c b/drivers/target/target_core_device.c
index 440e6b6..1185c3b 100644
--- a/drivers/target/target_core_device.c
+++ b/drivers/target/target_core_device.c
@@ -657,7 +657,7 @@
struct se_lun *se_lun;
struct se_session *se_sess = se_cmd->se_sess;
struct se_task *se_task;
- unsigned char *buf = se_cmd->t_task_buf;
+ unsigned char *buf;
u32 cdb_offset = 0, lun_count = 0, offset = 8, i;
list_for_each_entry(se_task, &se_cmd->t_task_list, t_list)
@@ -668,6 +668,8 @@
return PYX_TRANSPORT_LU_COMM_FAILURE;
}
+ buf = transport_kmap_first_data_page(se_cmd);
+
/*
* If no struct se_session pointer is present, this struct se_cmd is
* coming via a target_core_mod PASSTHROUGH op, and not through
@@ -704,6 +706,7 @@
* See SPC3 r07, page 159.
*/
done:
+ transport_kunmap_first_data_page(se_cmd);
lun_count *= 8;
buf[0] = ((lun_count >> 24) & 0xff);
buf[1] = ((lun_count >> 16) & 0xff);