[SCSI] iscsi_tcp, libiscsi: initial AHS Support
at libiscsi generic code
- currently code assumes a storage space of pdu header is allocated
at llds ctask and is pointed to by iscsi_cmd_task->hdr. Here I add
a hdr_max field pertaining to that storage, and an hdr_len that
accumulates the current use of the pdu-header.
- Add an iscsi_next_hdr() inline which returns the next free space
to write new Header at. Also iscsi_next_hdr() is used to retrieve
the address at which to write the header-digest.
- Add iscsi_add_hdr(length). What the user do is calls iscsi_next_hdr()
for address of the new header, than calls iscsi_add_hdr(length) with
the size of the new header. iscsi_add_hdr() will check if space is
available and update to the new size. length must be padded according
to standard.
- Add 2 padding inline helpers thanks to Olaf. Current patch does not
use them but Following patches will.
Also moved definition of ISCSI_PAD_LEN to iscsi_proto.h which had
PAD_WORD_LEN that was never used anywhere.
- Let iscsi_prep_scsi_cmd_pdu() signal an Error return since now it is
possible that it will fail.
- I was tired of yet again writing a "this is a digest" comment next to
sizeof(__u32) so I defined a new ISCSI_DIGEST_SIZE. Now I don't need
any comments. Changed all places that used sizeof(__u32) or "4" in
connection to a digest.
iscsi_tcp specific code
- At struct iscsi_tcp_cmd_task allocate maximum space allowed in
standard for all headers following the iscsi_cmd header. and mark
it so in iscsi_tcp_session_create()
- At iscsi_send_cmd_hdr() retrieve the correct headers size and
write header digest at iscsi_next_hdr().
Signed-off-by: Boaz Harrosh <bharrosh@panasas.com>
Signed-off-by: Olaf Kirch <olaf.kirch@oracle.com>
Signed-off-by: Mike Christie <michaelc@cs.wisc.edu>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
diff --git a/drivers/scsi/libiscsi.c b/drivers/scsi/libiscsi.c
index 0beb4c6..0d7914f 100644
--- a/drivers/scsi/libiscsi.c
+++ b/drivers/scsi/libiscsi.c
@@ -37,6 +37,9 @@
#include <scsi/scsi_transport_iscsi.h>
#include <scsi/libiscsi.h>
+static void fail_command(struct iscsi_conn *conn, struct iscsi_cmd_task *ctask,
+ int err);
+
struct iscsi_session *
class_to_transport_session(struct iscsi_cls_session *cls_session)
{
@@ -122,6 +125,20 @@
}
EXPORT_SYMBOL_GPL(iscsi_prep_unsolicit_data_pdu);
+static int iscsi_add_hdr(struct iscsi_cmd_task *ctask, unsigned len)
+{
+ unsigned exp_len = ctask->hdr_len + len;
+
+ if (exp_len > ctask->hdr_max) {
+ WARN_ON(1);
+ return -EINVAL;
+ }
+
+ WARN_ON(len & (ISCSI_PAD_LEN - 1)); /* caller must pad the AHS */
+ ctask->hdr_len = exp_len;
+ return 0;
+}
+
/**
* iscsi_prep_scsi_cmd_pdu - prep iscsi scsi cmd pdu
* @ctask: iscsi cmd task
@@ -129,13 +146,19 @@
* Prep basic iSCSI PDU fields for a scsi cmd pdu. The LLD should set
* fields like dlength or final based on how much data it sends
*/
-static void iscsi_prep_scsi_cmd_pdu(struct iscsi_cmd_task *ctask)
+static int iscsi_prep_scsi_cmd_pdu(struct iscsi_cmd_task *ctask)
{
struct iscsi_conn *conn = ctask->conn;
struct iscsi_session *session = conn->session;
struct iscsi_cmd *hdr = ctask->hdr;
struct scsi_cmnd *sc = ctask->sc;
+ unsigned hdrlength;
+ int rc;
+ ctask->hdr_len = 0;
+ rc = iscsi_add_hdr(ctask, sizeof(*hdr));
+ if (rc)
+ return rc;
hdr->opcode = ISCSI_OP_SCSI_CMD;
hdr->flags = ISCSI_ATTR_SIMPLE;
int_to_scsilun(sc->device->lun, (struct scsi_lun *)hdr->lun);
@@ -199,6 +222,15 @@
hdr->flags |= ISCSI_FLAG_CMD_READ;
}
+ /* calculate size of additional header segments (AHSs) */
+ hdrlength = ctask->hdr_len - sizeof(*hdr);
+
+ WARN_ON(hdrlength & (ISCSI_PAD_LEN-1));
+ hdrlength /= ISCSI_PAD_LEN;
+
+ WARN_ON(hdrlength >= 256);
+ hdr->hlength = hdrlength & 0xFF;
+
conn->scsicmd_pdus_cnt++;
debug_scsi("iscsi prep [%s cid %d sc %p cdb 0x%x itt 0x%x len %d "
@@ -206,6 +238,7 @@
sc->sc_data_direction == DMA_TO_DEVICE ? "write" : "read",
conn->id, sc, sc->cmnd[0], ctask->itt, scsi_bufflen(sc),
session->cmdsn, session->max_cmdsn - session->exp_cmdsn + 1);
+ return 0;
}
/**
@@ -744,7 +777,10 @@
conn->ctask = list_entry(conn->xmitqueue.next,
struct iscsi_cmd_task, running);
- iscsi_prep_scsi_cmd_pdu(conn->ctask);
+ if (iscsi_prep_scsi_cmd_pdu(conn->ctask)) {
+ fail_command(conn, conn->ctask, DID_ABORT << 16);
+ continue;
+ }
conn->session->tt->init_cmd_task(conn->ctask);
conn->ctask->state = ISCSI_TASK_RUNNING;
list_move_tail(conn->xmitqueue.next, &conn->run_list);
@@ -1534,6 +1570,7 @@
if (cmd_task_size)
ctask->dd_data = &ctask[1];
ctask->itt = cmd_i;
+ ctask->hdr_max = sizeof(struct iscsi_cmd);
INIT_LIST_HEAD(&ctask->running);
}