History log of /linux-master/drivers/scsi/sd_dif.c
Revision Date Author Comments
# 26a02d97 21-Feb-2023 Xingui Yang <yangxingui@huawei.com>

scsi: sd: Update DIX config every time sd_revalidate_disk() is called

If a controller has DIX is enabled and an attached disk is formatted using
a protection type supported by the controller, a block integrity profile is
registered to enable protected transfers.

If the disk is subsequently reformatted to disable PI, and the controller
does not support DIX Type 0, this can lead to failures such as this:

[142829.032340] hisi_sas_v3_hw 0000:b4:04.0: erroneous completion iptt=2375 task=00000000bea0970c dev id=5 direct-attached phy4 addr=51c20dbaf642a000 CQ hdr: 0x1023 0x50947 0x0 0x20000 Error info: 0x0 0x0 0x4 0x0
[142829.073883] sas: Enter sas_scsi_recover_host busy: 1 failed: 1
[142829.079783] sas: sas_scsi_find_task: aborting task 0x00000000bea0970c
[142829.102342] sas: Internal abort: task to dev 51c20dbaf642a000 response: 0x0 status 0x5
[142829.110319] sas: sas_eh_handle_sas_errors: task 0x00000000bea0970c is done
[142829.117275] sd 7:0:5:0: [sdc] tag#2375 UNKNOWN(0x2003) Result: hostbyte=0x05 driverbyte=DRIVER_OK cmd_age=0s
[142829.127171] sd 7:0:5:0: [sdc] tag#2375 CDB: opcode=0x2a 2a 00 00 00 00 00 00 00 08 00
[142829.135059] I/O error, dev sdc, sector 0 op 0x1:(WRITE) flags 0x18800 phys_seg 1 prio class 2

This is because the block layer integrity profile is currently only set up
the first time a disk is discovered.

To address this, remove the first_scan check when configuring protection
information during revalidate. Also unregister the block integrity profile
if DIX is not supported with a given protection type.

[mkp: commit description + printk dedup]

Link: https://lore.kernel.org/r/20230221081026.24736-1-yangxingui@huawei.com
Signed-off-by: Xingui Yang <yangxingui@huawei.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>


# 1e029397 01-Mar-2022 Martin K. Petersen <martin.petersen@oracle.com>

scsi: sd: Reorganize DIF/DIX code to avoid calling revalidate twice

During device discovery we ended up calling revalidate twice and thus
requested the same parameters multiple times. This was originally necessary
due to the request_queue and gendisk needing to be instantiated to
configure the block integrity profile.

Since this dependency no longer exists, reorganize the integrity probing
code so it can be run once at the end of discovery and drop the superfluous
revalidate call. Postponing the registration step involves splitting
sd_read_protection() into two functions, one to read the device protection
type and one to configure the mode of operation.

As part of this cleanup, make the printing code a bit less verbose.

Link: https://lore.kernel.org/r/20220302053559.32147-14-martin.petersen@oracle.com
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>


# fe45e630 20-Sep-2021 Christoph Hellwig <hch@lst.de>

block: move integrity handling out of <linux/blkdev.h>

Split the integrity/metadata handling definitions out into a new header.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Link: https://lore.kernel.org/r/20210920123328.1399408-17-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>


# a98c5b19 01-Jun-2019 Thomas Gleixner <tglx@linutronix.de>

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 410

Based on 1 normalized pattern(s):

this program is free software you can redistribute it and or modify
it under the terms of the gnu general public license version 2 as
published by the free software foundation this program is
distributed in the hope that it will be useful but without any
warranty without even the implied warranty of merchantability or
fitness for a particular purpose see the gnu general public license
for more details you should have received a copy of the gnu general
public license along with this program see the file copying if not
write to the free software foundation 675 mass ave cambridge ma
02139 usa

extracted by the scancode license scanner the SPDX license identifier

GPL-2.0-only

has been chosen to replace the boilerplate/reference in 3 file(s).

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Allison Randal <allison@lohutok.net>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190531190112.675111872@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>


# b0edc7fd 30-Apr-2019 Christoph Hellwig <hch@lst.de>

scsi: sd: switch remaining files to SPDX tags

Use the the GPLv2 SPDX tag instead of verbose boilerplate text.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>


# 10c41ddd 29-Jul-2018 Max Gurtovoy <maxg@mellanox.com>

block: move dif_prepare/dif_complete functions to block layer

Currently these functions are implemented in the scsi layer, but their
actual place should be the block layer since T10-PI is a general data
integrity feature that is used in the nvme protocol as well. Also, use
the tuple size from the integrity profile since it may vary between
integrity types.

Suggested-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Max Gurtovoy <maxg@mellanox.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>


# ddd0bc75 29-Jul-2018 Max Gurtovoy <maxg@mellanox.com>

block: move ref_tag calculation func to the block layer

Currently this function is implemented in the scsi layer, but it's
actual place should be the block layer since T10-PI is a general
data integrity feature that is used in the nvme protocol as well.

Suggested-by: Christoph Hellwig <hch@lst.de>
Cc: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Max Gurtovoy <maxg@mellanox.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>


# 8475c811 11-Sep-2016 Christoph Hellwig <hch@lst.de>

scsi: sd: Move DIF protection types to t10-pi.h

These should go together with the rest of the T10 protection information
defintions.

[mkp: s/T10_DIF/T10_PI/]

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Bart Van Assche <bart.vanassche@sandisk.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>


# 0f8087ec 21-Oct-2015 Martin K. Petersen <martin.petersen@oracle.com>

block: Consolidate static integrity profile properties

We previously made a complete copy of a device's data integrity profile
even though several of the fields inside the blk_integrity struct are
pointers to fixed template entries in t10-pi.c.

Split the static and per-device portions so that we can reference the
template directly.

Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Reported-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Sagi Grimberg <sagig@mellanox.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Jens Axboe <axboe@fb.com>


# e557990e 14-Apr-2015 Martin K. Petersen <martin.petersen@oracle.com>

sd: Fix missing ATO tag check

3aec2f41a8bae introduced a merge error where we would end up check for
sdkp instead of sdkp->ATO. Fix this so we register app tag capability
correctly.

Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Cc: <stable@vger.kernel.org> # v3.17+
Reviewed-by: Sagi Grimberg <sagig@mellanox.com>
Signed-off-by: James Bottomley <JBottomley@Odin.com>


# c611529e 26-Sep-2014 Martin K. Petersen <martin.petersen@oracle.com>

sd: Honor block layer integrity handling flags

A set of flags introduced in the block layer enable better control over
how protection information is handled. These flags are useful for both
error injection and data recovery purposes. Checking can be enabled and
disabled for controller and disk, and the guard tag format is now a
per-I/O property.

Update sd_protect_op to communicate the relevant information to the
low-level device driver via a set of flags in scsi_cmnd.

Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Reviewed-by: Sagi Grimberg <sagig@mellanox.com>
Acked-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@fb.com>


# 2341c2f8 26-Sep-2014 Martin K. Petersen <martin.petersen@oracle.com>

block: Add T10 Protection Information functions

The T10 Protection Information format is also used by some devices that
do not go through the SCSI layer (virtual block devices, NVMe). Relocate
the relevant functions to a block layer library that can be used without
involving SCSI.

Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@fb.com>


# aae7df50 26-Sep-2014 Martin K. Petersen <martin.petersen@oracle.com>

block: Integrity checksum flag

Make the choice of checksum a per-I/O property by introducing a flag
that can be inspected by the SCSI layer. There are several reasons for
this:

1. It allows us to switch choice of checksum without unloading and
reloading the HBA driver.

2. During error recovery we need to be able to tell the HBA that
checksums read from disk should not be verified and converted to IP
checksums.

3. For error injection purposes we need to be able to write a bad guard
tag to storage. Since the storage device only supports T10 CRC we
need to be able to disable IP checksum conversion on the HBA.

Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Reviewed-by: Sagi Grimberg <sagig@mellanox.com>
Signed-off-by: Jens Axboe <axboe@fb.com>


# b1f013885 26-Sep-2014 Martin K. Petersen <martin.petersen@oracle.com>

block: Relocate bio integrity flags

Move flags affecting the integrity code out of the bio bi_flags and into
the block integrity payload.

Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Reviewed-by: Sagi Grimberg <sagig@mellanox.com>
Signed-off-by: Jens Axboe <axboe@fb.com>


# 3aec2f41 26-Sep-2014 Martin K. Petersen <martin.petersen@oracle.com>

block: Add a disk flag to block integrity profile

So far we have relied on the app tag size to determine whether a disk
has been formatted with T10 protection information or not. However, not
all target devices provide application tag storage.

Add a flag to the block integrity profile that indicates whether the
disk has been formatted with protection information.

Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Reviewed-by: Sagi Grimberg <sagig@dev.mellanox.co.il>
Signed-off-by: Jens Axboe <axboe@fb.com>


# 18593088 26-Sep-2014 Martin K. Petersen <martin.petersen@oracle.com>

block: Clean up the code used to generate and verify integrity metadata

Instead of the "operate" parameter we pass in a seed value and a pointer
to a function that can be used to process the integrity metadata. The
generation function is changed to have a return value to fit into this
scheme.

Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Reviewed-by: Sagi Grimberg <sagig@mellanox.com>
Signed-off-by: Jens Axboe <axboe@fb.com>


# 3be91c4a 26-Sep-2014 Martin K. Petersen <martin.petersen@oracle.com>

block: Deprecate the use of the term sector in the context of block integrity

The protection interval is not necessarily tied to the logical block
size of a block device. Stop using the terms "sector" and "sectors".

Going forward we will use the term "seed" to describe the initial
reference tag value for a given I/O. "Interval" will be used to describe
the portion of the data buffer that a given piece of protection
information is associated with.

Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Sagi Grimberg <sagig@mellanox.com>
Signed-off-by: Jens Axboe <axboe@fb.com>


# 8492b68b 26-Sep-2014 Martin K. Petersen <martin.petersen@oracle.com>

block: Remove integrity tagging functions

None of the filesystems appear interested in using the integrity tagging
feature. Potentially because very few storage devices actually permit
using the application tag space.

Remove the tagging functions.

Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Sagi Grimberg <sagig@mellanox.com>
Signed-off-by: Jens Axboe <axboe@fb.com>


# 180b2f95 26-Sep-2014 Martin K. Petersen <martin.petersen@oracle.com>

block: Replace bi_integrity with bi_special

For commands like REQ_COPY we need a way to pass extra information along
with each bio. Like integrity metadata this information must be
available at the bottom of the stack so bi_private does not suffice.

Rename the existing bi_integrity field to bi_special and make it a union
so we can have different bio extensions for each class of command.

We previously used bi_integrity != NULL as a way to identify whether a
bio had integrity metadata or not. Introduce a REQ_INTEGRITY to be the
indicator now that bi_special can contain different things.

In addition, bio_integrity(bio) will now return a pointer to the
integrity payload (when applicable).

Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Sagi Grimberg <sagig@mellanox.com>
Signed-off-by: Jens Axboe <axboe@fb.com>


# d57a5f7c 23-Nov-2013 Kent Overstreet <kmo@daterainc.com>

bio-integrity: Convert to bvec_iter

The bio integrity is also stored in a bvec array, so if we use the bvec
iter code we just added, the integrity code won't need to implement its
own iteration stuff (bio_integrity_mark_head(), bio_integrity_mark_tail())

Signed-off-by: Kent Overstreet <kmo@daterainc.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: "Martin K. Petersen" <martin.petersen@oracle.com>
Cc: "James E.J. Bottomley" <JBottomley@parallels.com>


# 025a1f50 18-Apr-2013 Jeremy Higdon <jeremy@sgi.com>

[SCSI] sd_dif: problem with verify of type 1 protection information (PI)

It appears to me that there is a problem with handling of type 1 protection
information.

It is considering a logical block reference tag of 0xffffffff to be an error,
but it is actually valid any time ((lba & 0xffffffff) == 0xffffffff) [for
example, 2TiB-1, 4TiB-1, 6TiB-1, etc.].

I'm going by what's written in 4.18.3 of SBC3, where there doesn't appear
to be any invalid value for the reference tag.

Signed-off-by: Jeremy Higdon <jeremy@sgi.com>
Acked-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>


# 8c579ab6 28-Aug-2012 Martin K. Petersen <martin.petersen@oracle.com>

[SCSI] sd: Avoid remapping bad reference tags

It does not make sense to translate ref tags with unexpected values.
Instead we simply ignore them and let the upper layers catch the
problem. Ref tags that contain the expected value are still remapped.

Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>


# 77dfce07 25-Nov-2011 Cong Wang <amwang@redhat.com>

scsi: remove the second argument of k[un]map_atomic()

Signed-off-by: Cong Wang <amwang@redhat.com>


# 9354f1b8 05-Mar-2012 Muthu Kumar <muthu.lkml@gmail.com>

floppy/scsi: fix setting of BIO flags

Fix setting bio flags in drivers (sd_dif/floppy).

Signed-off-by: Muthukumar R <muthur@gmail.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: James Bottomley <James.Bottomley@HansenPartnership.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>


# 12ebffd1 02-Mar-2012 Muthukumar R <muthur@gmail.com>

block: Fix setting bio flags in drivers (sd_dif/floppy)

Fix setting bio flags in drivers (sd_dif/floppy).

Signed-off-by: Muthukumar R <muthur@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>


# 495d2b38 15-Oct-2010 Martin K. Petersen <martin.petersen@oracle.com>

block: Make the integrity mapped property a bio flag

Previously we tracked whether the integrity metadata had been remapped
using a request flag. This was fine for low-level retries. However, if
an I/O was redriven by upper layers we would end up remapping again,
causing the retry to fail.

Deprecate the REQ_INTEGRITY flag and introduce BIO_MAPPED_INTEGRITY
which enables filesystems to notify lower layers that the bio in
question has already been remapped.

Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>


# 3bf3583b 09-Nov-2009 Martin K. Petersen <martin.petersen@oracle.com>

[SCSI] sd: Return correct error code for DIF

sd_dif.c was not updated to return -EILSEQ, leading to error handling
failures in applications which provide their own integrity metadata (as
opposed to being protected by the block layer functions).

Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: James Bottomley <James.Bottomley@suse.de>


# 35e1a5d9 18-Sep-2009 Martin K. Petersen <martin.petersen@oracle.com>

[SCSI] sd: Detach DIF from block integrity infrastructure

So far we have only issued DIF commands if CONFIG_BLK_DEV_INTEGRITY is
enabled. However, communication between initiator and target should be
independent of protection information DMA. There are DIF-only host
adapters coming out that will be able to take advantage of this.

Move the relevant DIF bits to sd.c.

Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: James Bottomley <James.Bottomley@suse.de>


# c6af4042 18-Sep-2009 Martin K. Petersen <martin.petersen@oracle.com>

[SCSI] Deprecate SCSI_PROT_*_CONVERT operations

The checksum format is orthogonal to whether the protection information
is being passed on beyond the HBA or not. It is perfectly valid to use
a non-T10 CRC with WRITE_STRIP and READ_INSERT.

Consequently it no longer makes sense to explicitly refer to the
conversion in the protection operation. Update sd_dif and lpfc
accordingly.

Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Acked-by: Ihab Hamadi <Ihab.Hamadi@Emulex.Com>
Signed-off-by: James Bottomley <James.Bottomley@suse.de>


# 83096ebf 07-May-2009 Tejun Heo <tj@kernel.org>

block: convert to pos and nr_sectors accessors

With recent cleanups, there is no place where low level driver
directly manipulates request fields. This means that the 'hard'
request fields always equal the !hard fields. Convert all
rq->sectors, nr_sectors and current_nr_sectors references to
accessors.

While at it, drop superflous blk_rq_pos() < 0 test in swim.c.

[ Impact: use pos and nr_sectors accessors ]

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Geert Uytterhoeven <Geert.Uytterhoeven@sonycom.com>
Tested-by: Grant Likely <grant.likely@secretlab.ca>
Acked-by: Grant Likely <grant.likely@secretlab.ca>
Tested-by: Adrian McMenamin <adrian@mcmen.demon.co.uk>
Acked-by: Adrian McMenamin <adrian@mcmen.demon.co.uk>
Acked-by: Mike Miller <mike.miller@hp.com>
Cc: James Bottomley <James.Bottomley@HansenPartnership.com>
Cc: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
Cc: Borislav Petkov <petkovbb@googlemail.com>
Cc: Sergei Shtylyov <sshtylyov@ru.mvista.com>
Cc: Eric Moore <Eric.Moore@lsi.com>
Cc: Alan Stern <stern@rowland.harvard.edu>
Cc: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Cc: Pete Zaitcev <zaitcev@redhat.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Paul Clements <paul.clements@steeleye.com>
Cc: Tim Waugh <tim@cyberelk.net>
Cc: Jeff Garzik <jgarzik@pobox.com>
Cc: Jeremy Fitzhardinge <jeremy@xensource.com>
Cc: Alex Dubov <oakad@yahoo.com>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Dario Ballabio <ballabio_dario@emc.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: unsik Kim <donari75@gmail.com>
Cc: Laurent Vivier <Laurent@lvivier.info>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>


# 5db524bd 04-Jan-2009 Martin K. Petersen <martin.petersen@oracle.com>

[SCSI] sd: Correctly handle 6-byte commands with DIX

DIF does not work with 6-byte commands so we previously ignored those
commands when preparing a request. However, DIX does not need
RDPROTECT/WRPROTECT to be set and 6-byte commands are consequently
perfectly valid in host-only mode.

This patch fixes a problem where we would set the wrong DIX operation
when issuing commands to a legacy disk.

Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Reviewed-by: Matthew Wilcox <willy@linux.intel.com>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>


# becce74b 04-Jan-2009 Martin K. Petersen <martin.petersen@oracle.com>

[SCSI] sd: DIF: Fix tagging on platforms with signed char

Switch tag arrays to u8 to prevent problems on platforms with signed
char.

Reported-by: Tim LaBerge <tim.laberge@Quantum.Com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>


# 10da5181 04-Jan-2009 Martin K. Petersen <martin.petersen@oracle.com>

[SCSI] sd: DIF: Show app tag on error

Add application tag to the output displayed on error.

Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>


# cbdc1445 30-Sep-2008 Martin K. Petersen <martin.petersen@oracle.com>

[SCSI] sd: Switch kernel printing level for DIF messages

For some reason these messages ended up being printed with KERN_INFO
rendering them invisible to pretty much everyone. Switch to
KERN_NOTICE.

Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>


# 9e06688e 19-Sep-2008 Martin K. Petersen <martin.petersen@oracle.com>

[SCSI] sd: Correctly handle all combinations of DIF and DIX

The old detection code couldn't handle all possible combinations of
DIX and DIF. This version does, giving priority to DIX if the
controller is capable.

Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>


# be922f47 19-Sep-2008 Martin K. Petersen <martin.petersen@oracle.com>

[SCSI] sd: Always print actual protection_type

Now that we no longer use protection_type as trigger for preparing
protected CDBs we can remove the places that set it to zero. This
allows userland to see which protection type the device is formatted
with regardless of whether the HBA supports DIF or not.

Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>


# af55ff67 17-Jul-2008 Martin K. Petersen <martin.petersen@oracle.com>

[SCSI] sd: Support for SCSI disk (SBC) Data Integrity Field

Support for controllers and disks that implement DIF protection
information:

- During command preparation the RDPROTECT/WRPROTECT must be set
correctly if the target has DIF enabled.

- READ(6) and WRITE(6) are not supported when DIF is on.

- The controller must be told how to handle the I/O via the
protection operation field in scsi_cmnd.

- Refactor the I/O completion code that extracts failed LBA from the
returned sense data and handle DIF failures correctly.

- sd_dif.c implements the functions required to prepare and complete
requests with protection information attached.

Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>