[SCSI] scsi_lib: fix scsi_io_completion's SG_IO error propagation

The following v3.4-rc1 commit unmasked an existing bug in scsi_io_completion's
SG_IO error handling: 47ac56d [SCSI] scsi_error: classify some ILLEGAL_REQUEST
sense as a permanent TARGET_ERROR

Given that certain ILLEGAL_REQUEST are now properly categorized as
TARGET_ERROR the host_byte is being set (before host_byte wasn't ever
set for these ILLEGAL_REQUEST).

In scsi_io_completion, initialize req->errors with cmd->result _after_
the SG_IO block that calls __scsi_error_from_host_byte (which may
modify the host_byte).

Before this fix:

    cdb to send: 12 01 01 00 00 00
ioctl(3, SG_IO, {'S', SG_DXFER_NONE, cmd[6]=[12, 01, 01, 00, 00, 00],
    mx_sb_len=32, iovec_count=0, dxfer_len=0, timeout=20000, flags=0,
    status=02, masked_status=01, sb[19]=[70, 00, 05, 00, 00, 00, 00, 0b,
    00, 00, 00, 00, 24, 00, 00, 00, 00, 00, 00], host_status=0x10,
    driver_status=0x8, resid=0, duration=0, info=0x1}) = 0
SCSI Status: Check Condition

Sense Information:
sense buffer empty

After:

    cdb to send: 12 01 01 00 00 00
ioctl(3, SG_IO, {'S', SG_DXFER_NONE, cmd[6]=[12, 01, 01, 00, 00, 00],
    mx_sb_len=32, iovec_count=0, dxfer_len=0, timeout=20000, flags=0,
    status=02, masked_status=01, sb[19]=[70, 00, 05, 00, 00, 00, 00, 0b,
    00, 00, 00, 00, 24, 00, 00, 00, 00, 00, 00], host_status=0,
    driver_status=0x8, resid=0, duration=0, info=0x1}) = 0
SCSI Status: Check Condition

Sense Information:
 Fixed format, current;  Sense key: Illegal Request
 Additional sense: Invalid field in cdb
 Raw sense data (in hex):
        70 00 05 00 00 00 00 0b  00 00 00 00 24 00 00 00
        00 00 00

Reported-by: Paolo Bonzini <pbonzini@redhat.com>
Tested-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Reviewed-by: Babu Moger <babu.moger@netapp.com>
Cc: stable@vger.kernel.org # 3.4
Signed-off-by: James Bottomley <JBottomley@Parallels.com>

1 files changed, 4 insertions, 1 deletions

diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index ffd77739ae3e..faa790fba134 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -776,7 +776,6 @@ void scsi_io_completion(struct scsi_cmnd *cmd, unsigned int good_bytes)
         }
 
         if (req->cmd_type == REQ_TYPE_BLOCK_PC) { /* SG_IO ioctl from block level */
-                req->errors = result;
                 if (result) {
                         if (sense_valid && req->sense) {
                                 /*
@@ -792,6 +791,10 @@ void scsi_io_completion(struct scsi_cmnd *cmd, unsigned int good_bytes)
                         if (!sense_deferred)
                                 error = __scsi_error_from_host_byte(cmd, result);
                 }
+                /*
+                 * __scsi_error_from_host_byte may have reset the host_byte
+                 */
+                req->errors = cmd->result;
 
                 req->resid_len = scsi_get_resid(cmd);