TCMU: Fix possible overwrite of t_data_sg's last iov[] and wrongly calculating base_command_size

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---Problem Description---
If there has BIDI data, its first iov[] will overwrite the last
iov[] for se_cmd->t_data_sg.

---uname output---
Latest Yakkety master branch

Machine Type = P8

---Steps to Reproduce---
 Just have a system do workload using tcmu.

Stack trace output:
 I have seen this in my environment:
(gdb) print *((tcmulib_cmd->iovec)+0)
$7 = {iov_base = 0x3fff7c3d0000, iov_len = 8192}
(gdb) print *((tcmulib_cmd->iovec)+1)
$3 = {iov_base = 0x3fff7c3da000, iov_len = 4096}
(gdb) print *((tcmulib_cmd->iovec)+2)
$4 = {iov_base = 0x3fff7c3dc000, iov_len = 16384}
(gdb) print *((tcmulib_cmd->iovec)+3)
$5 = {iov_base = 0x3fff7c3f7000, iov_len = 12288}
(gdb) print *((tcmulib_cmd->iovec)+4)
$6 = {iov_base = 0x1306e853c0028, iov_len = 128} <--- bad pointer and length

cmu: Fix wrongly calculating of the base_command_size
https://patchwork.kernel.org/patch/9687657/

tcmu: Fix possible overwrite of t_data_sg's last iov[]
https://patchwork.kernel.org/patch/9687565/

tcmu: Skip Data-Out blocks before gathering Data-In buffer for BIDI case

https://patchwork.kernel.org/patch/9655423/

This patch should also be a part of these fixes. WITH BIDI op fixes.

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Default Comment by Bridge

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Default Comment by Bridge

[Joseph Salisbury (jsalisbury)]

Yakkety is EOL on July 20th. Does this bug affect any other releases?

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------- Comment From <email address hidden> 2017-08-03 13:56 EDT-------
No this bug does not affect any other releases. Zesty already has the fix in it.