[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>

1 files changed, 8 insertions, 8 deletions

diff --git a/drivers/scsi/iscsi_tcp.c b/drivers/scsi/iscsi_tcp.c
index fd88777df28b..491845f18710 100644
--- a/drivers/scsi/iscsi_tcp.c
+++ b/drivers/scsi/iscsi_tcp.c
@@ -113,7 +113,7 @@ iscsi_hdr_digest(struct iscsi_conn *conn, struct iscsi_buf *buf,
         struct iscsi_tcp_conn *tcp_conn = conn->dd_data;
 
         crypto_hash_digest(&tcp_conn->tx_hash, &buf->sg, buf->sg.length, crc);
-        buf->sg.length += sizeof(u32);
+        buf->sg.length += ISCSI_DIGEST_SIZE;
 }
 
 /*
@@ -220,6 +220,7 @@ static inline int
 iscsi_tcp_chunk_done(struct iscsi_chunk *chunk)
 {
         static unsigned char padbuf[ISCSI_PAD_LEN];
+        unsigned int pad;
 
         if (chunk->copied < chunk->size) {
                 iscsi_tcp_chunk_map(chunk);
@@ -243,10 +244,8 @@ iscsi_tcp_chunk_done(struct iscsi_chunk *chunk)
         }
 
         /* Do we need to handle padding? */
-        if (chunk->total_copied & (ISCSI_PAD_LEN-1)) {
-                unsigned int pad;
-
-                pad = ISCSI_PAD_LEN - (chunk->total_copied & (ISCSI_PAD_LEN-1));
+        pad = iscsi_padding(chunk->total_copied);
+        if (pad != 0) {
                 debug_tcp("consume %d pad bytes\n", pad);
                 chunk->total_size += pad;
                 chunk->size = pad;
@@ -1385,11 +1384,11 @@ iscsi_send_cmd_hdr(struct iscsi_conn *conn, struct iscsi_cmd_task *ctask)
                 }
 
                 iscsi_buf_init_iov(&tcp_ctask->headbuf, (char*)ctask->hdr,
-                                  sizeof(struct iscsi_hdr));
+                                  ctask->hdr_len);
 
                 if (conn->hdrdgst_en)
                         iscsi_hdr_digest(conn, &tcp_ctask->headbuf,
-                                         (u8*)tcp_ctask->hdrext);
+                                         iscsi_next_hdr(ctask));
                 tcp_ctask->xmstate &= ~XMSTATE_CMD_HDR_INIT;
                 tcp_ctask->xmstate |= XMSTATE_CMD_HDR_XMIT;
         }
@@ -2176,7 +2175,8 @@ iscsi_tcp_session_create(struct iscsi_transport *iscsit,
                 struct iscsi_cmd_task *ctask = session->cmds[cmd_i];
                 struct iscsi_tcp_cmd_task *tcp_ctask = ctask->dd_data;
 
-                ctask->hdr = &tcp_ctask->hdr;
+                ctask->hdr = &tcp_ctask->hdr.cmd_hdr;
+                ctask->hdr_max = sizeof(tcp_ctask->hdr) - ISCSI_DIGEST_SIZE;
         }
 
         for (cmd_i = 0; cmd_i < session->mgmtpool_max; cmd_i++) {