t10-pi.c
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/*
* t10_pi.c - Functions for generating and verifying T10 Protection
* Information.
*
* Copyright (C) 2007, 2008, 2014 Oracle Corporation
* Written by: Martin K. Petersen <martin.petersen@oracle.com>
*
* 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.
*
*/
#include <linux/t10-pi.h>
#include <linux/blkdev.h>
#include <linux/crc-t10dif.h>
#include <net/checksum.h>
typedef __be16 (csum_fn) (void *, unsigned int);
static const __be16 APP_ESCAPE = (__force __be16) 0xffff;
static const __be32 REF_ESCAPE = (__force __be32) 0xffffffff;
static __be16 t10_pi_crc_fn(void *data, unsigned int len)
{
return cpu_to_be16(crc_t10dif(data, len));
}
static __be16 t10_pi_ip_fn(void *data, unsigned int len)
{
return (__force __be16)ip_compute_csum(data, len);
}
/*
* Type 1 and Type 2 protection use the same format: 16 bit guard tag,
* 16 bit app tag, 32 bit reference tag. Type 3 does not define the ref
* tag.
*/
static int t10_pi_generate(struct blk_integrity_iter *iter, csum_fn *fn,
unsigned int type)
{
unsigned int i;
for (i = 0 ; i < iter->data_size ; i += iter->interval) {
struct t10_pi_tuple *pi = iter->prot_buf;
pi->guard_tag = fn(iter->data_buf, iter->interval);
pi->app_tag = 0;
if (type == 1)
pi->ref_tag = cpu_to_be32(lower_32_bits(iter->seed));
else
pi->ref_tag = 0;
iter->data_buf += iter->interval;
iter->prot_buf += sizeof(struct t10_pi_tuple);
iter->seed++;
}
return 0;
}
static int t10_pi_verify(struct blk_integrity_iter *iter, csum_fn *fn,
unsigned int type)
{
unsigned int i;
for (i = 0 ; i < iter->data_size ; i += iter->interval) {
struct t10_pi_tuple *pi = iter->prot_buf;
__be16 csum;
switch (type) {
case 1:
case 2:
if (pi->app_tag == APP_ESCAPE)
goto next;
if (be32_to_cpu(pi->ref_tag) !=
lower_32_bits(iter->seed)) {
pr_err("%s: ref tag error at location %llu " \
"(rcvd %u)\n", iter->disk_name,
(unsigned long long)
iter->seed, be32_to_cpu(pi->ref_tag));
return -EILSEQ;
}
break;
case 3:
if (pi->app_tag == APP_ESCAPE &&
pi->ref_tag == REF_ESCAPE)
goto next;
break;
}
csum = fn(iter->data_buf, iter->interval);
if (pi->guard_tag != csum) {
pr_err("%s: guard tag error at sector %llu " \
"(rcvd %04x, want %04x)\n", iter->disk_name,
(unsigned long long)iter->seed,
be16_to_cpu(pi->guard_tag), be16_to_cpu(csum));
return -EILSEQ;
}
next:
iter->data_buf += iter->interval;
iter->prot_buf += sizeof(struct t10_pi_tuple);
iter->seed++;
}
return 0;
}
static int t10_pi_type1_generate_crc(struct blk_integrity_iter *iter)
{
return t10_pi_generate(iter, t10_pi_crc_fn, 1);
}
static int t10_pi_type1_generate_ip(struct blk_integrity_iter *iter)
{
return t10_pi_generate(iter, t10_pi_ip_fn, 1);
}
static int t10_pi_type1_verify_crc(struct blk_integrity_iter *iter)
{
return t10_pi_verify(iter, t10_pi_crc_fn, 1);
}
static int t10_pi_type1_verify_ip(struct blk_integrity_iter *iter)
{
return t10_pi_verify(iter, t10_pi_ip_fn, 1);
}
static int t10_pi_type3_generate_crc(struct blk_integrity_iter *iter)
{
return t10_pi_generate(iter, t10_pi_crc_fn, 3);
}
static int t10_pi_type3_generate_ip(struct blk_integrity_iter *iter)
{
return t10_pi_generate(iter, t10_pi_ip_fn, 3);
}
static int t10_pi_type3_verify_crc(struct blk_integrity_iter *iter)
{
return t10_pi_verify(iter, t10_pi_crc_fn, 3);
}
static int t10_pi_type3_verify_ip(struct blk_integrity_iter *iter)
{
return t10_pi_verify(iter, t10_pi_ip_fn, 3);
}
struct blk_integrity t10_pi_type1_crc = {
.name = "T10-DIF-TYPE1-CRC",
.generate_fn = t10_pi_type1_generate_crc,
.verify_fn = t10_pi_type1_verify_crc,
.tuple_size = sizeof(struct t10_pi_tuple),
.tag_size = 0,
};
EXPORT_SYMBOL(t10_pi_type1_crc);
struct blk_integrity t10_pi_type1_ip = {
.name = "T10-DIF-TYPE1-IP",
.generate_fn = t10_pi_type1_generate_ip,
.verify_fn = t10_pi_type1_verify_ip,
.tuple_size = sizeof(struct t10_pi_tuple),
.tag_size = 0,
};
EXPORT_SYMBOL(t10_pi_type1_ip);
struct blk_integrity t10_pi_type3_crc = {
.name = "T10-DIF-TYPE3-CRC",
.generate_fn = t10_pi_type3_generate_crc,
.verify_fn = t10_pi_type3_verify_crc,
.tuple_size = sizeof(struct t10_pi_tuple),
.tag_size = 0,
};
EXPORT_SYMBOL(t10_pi_type3_crc);
struct blk_integrity t10_pi_type3_ip = {
.name = "T10-DIF-TYPE3-IP",
.generate_fn = t10_pi_type3_generate_ip,
.verify_fn = t10_pi_type3_verify_ip,
.tuple_size = sizeof(struct t10_pi_tuple),
.tag_size = 0,
};
EXPORT_SYMBOL(t10_pi_type3_ip);