[SCSI] iscsi_tcp: fix padding, data digests, and IO at weird offsets

iscsi_tcp calculates padding by using the expected transfer length. This
has the problem where if we have immediate data = no and initial R2T =
yes, and the transfer length ended up needing padding then we send:

1. header
2. padding which should have gone after data
3. data

Besides this bug, we also assume the target will always ask for nice
transfer lengths and the first burst length will always be a nice value.
As far as I can tell form the RFC this is not a requirement. It would be
silly to do this, but if someone did it we will end doing bad things.

Finally the last bug in that bit of code is in our handling of the
recalculation of data digests when we do not send a whole iscsi_buf in
one try. The bug here is that we call crypto_digest_final on a
iscsi_sendpage error, then when we send the rest of the iscsi_buf, we
doiscsi_data_digest_init and this causes the previous data digest to be
lost.

And to make matters worse, some of these bugs are replicated over and
over and over again for immediate data, solicited data and unsolicited
data. So the attached patch made over the iscsi git tree (see
kernel.org/git for details) which I updated today to include the patches
I said I merged, consolidates the sending of data, padding and digests
and calculation of data digests and fixes the above bugs.

Signed-off-by: Mike Christie <michaelc@cs.wisc.edu>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>

1 files changed, 14 insertions, 19 deletions

diff --git a/drivers/scsi/iscsi_tcp.h b/drivers/scsi/iscsi_tcp.h
index aace8f70dfd7..7e40e94d9fdc 100644
--- a/drivers/scsi/iscsi_tcp.h
+++ b/drivers/scsi/iscsi_tcp.h
@@ -31,23 +31,21 @@
 #define IN_PROGRESS_DDIGEST_RECV        0x3
 
 /* xmit state machine */
-#define XMSTATE_IDLE                    0x0
-#define XMSTATE_R_HDR                   0x1
-#define XMSTATE_W_HDR                   0x2
-#define XMSTATE_IMM_HDR                 0x4
-#define XMSTATE_IMM_DATA                0x8
-#define XMSTATE_UNS_INIT                0x10
-#define XMSTATE_UNS_HDR                 0x20
-#define XMSTATE_UNS_DATA                0x40
-#define XMSTATE_SOL_HDR                 0x80
-#define XMSTATE_SOL_DATA                0x100
-#define XMSTATE_W_PAD                   0x200
-#define XMSTATE_DATA_DIGEST             0x400
-
-#define ISCSI_CONN_RCVBUF_MIN           262144
-#define ISCSI_CONN_SNDBUF_MIN           262144
+#define XMSTATE_IDLE                    0x0
+#define XMSTATE_R_HDR                   0x1
+#define XMSTATE_W_HDR                   0x2
+#define XMSTATE_IMM_HDR                 0x4
+#define XMSTATE_IMM_DATA                0x8
+#define XMSTATE_UNS_INIT                0x10
+#define XMSTATE_UNS_HDR                 0x20
+#define XMSTATE_UNS_DATA                0x40
+#define XMSTATE_SOL_HDR                 0x80
+#define XMSTATE_SOL_DATA                0x100
+#define XMSTATE_W_PAD                   0x200
+#define XMSTATE_W_RESEND_PAD            0x400
+#define XMSTATE_W_RESEND_DATA_DIGEST    0x800
+
 #define ISCSI_PAD_LEN                   4
-#define ISCSI_R2T_MAX                   16
 #define ISCSI_SG_TABLESIZE              SG_ALL
 #define ISCSI_TCP_MAX_CMD_LEN           16
 
@@ -162,13 +160,10 @@ struct iscsi_tcp_cmd_task {
         struct iscsi_queue      r2tpool;
         struct kfifo            *r2tqueue;
         struct iscsi_r2t_info   **r2ts;
-        uint32_t                datadigest;             /* for recover digest */
         int                     digest_count;
         uint32_t                immdigest;              /* for imm data */
         struct iscsi_buf        immbuf;                 /* for imm data digest */
-        struct iscsi_data_task  *dtask;         /* data task in progress*/
         struct iscsi_data_task  unsol_dtask;    /* unsol data task */
-        int                     digest_offset;  /* for partial buff digest */
 };
 
 #endif /* ISCSI_H */