drivers/scsi/sd_dif.c

   1 /*
   2  * sd_dif.c - SCSI Data Integrity Field
   3  *
   4  * Copyright (C) 2007, 2008 Oracle Corporation
   5  * Written by: Martin K. Petersen <martin.petersen@oracle.com>
   6  *
   7  * This program is free software; you can redistribute it and/or
   8  * modify it under the terms of the GNU General Public License version
   9  * 2 as published by the Free Software Foundation.
  10  *
  11  * This program is distributed in the hope that it will be useful, but
  12  * WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14  * General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * along with this program; see the file COPYING.  If not, write to
  18  * the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139,
  19  * USA.
  20  *
  21  */
  22
  23 #include <linux/blkdev.h>
  24 #include <linux/t10-pi.h>
  25
  26 #include <scsi/scsi.h>
  27 #include <scsi/scsi_cmnd.h>
  28 #include <scsi/scsi_dbg.h>
  29 #include <scsi/scsi_device.h>
  30 #include <scsi/scsi_driver.h>
  31 #include <scsi/scsi_eh.h>
  32 #include <scsi/scsi_host.h>
  33 #include <scsi/scsi_ioctl.h>
  34 #include <scsi/scsicam.h>
  35
  36 #include "sd.h"
  37
  38 /*
  39  * Configure exchange of protection information between OS and HBA.
  40  */
  41 void sd_dif_config_host(struct scsi_disk *sdkp)
  42 {
  43         struct scsi_device *sdp = sdkp->device;
  44         struct gendisk *disk = sdkp->disk;
  45         u8 type = sdkp->protection_type;
  46         struct blk_integrity bi;
  47         int dif, dix;
  48
  49         dif = scsi_host_dif_capable(sdp->host, type);
  50         dix = scsi_host_dix_capable(sdp->host, type);
  51
  52         if (!dix && scsi_host_dix_capable(sdp->host, 0)) {
  53                 dif = 0; dix = 1;
  54         }
  55
  56         if (!dix)
  57                 return;
  58
  59         memset(&bi, 0, sizeof(bi));
  60
  61         /* Enable DMA of protection information */
  62         if (scsi_host_get_guard(sdkp->device->host) & SHOST_DIX_GUARD_IP) {
  63                 if (type == T10_PI_TYPE3_PROTECTION)
  64                         bi.profile = &t10_pi_type3_ip;
  65                 else
  66                         bi.profile = &t10_pi_type1_ip;
  67
  68                 bi.flags |= BLK_INTEGRITY_IP_CHECKSUM;
  69         } else
  70                 if (type == T10_PI_TYPE3_PROTECTION)
  71                         bi.profile = &t10_pi_type3_crc;
  72                 else
  73                         bi.profile = &t10_pi_type1_crc;
  74
  75         bi.tuple_size = sizeof(struct t10_pi_tuple);
  76         sd_printk(KERN_NOTICE, sdkp,
  77                   "Enabling DIX %s protection\n", bi.profile->name);
  78
  79         if (dif && type) {
  80                 bi.flags |= BLK_INTEGRITY_DEVICE_CAPABLE;
  81
  82                 if (!sdkp->ATO)
  83                         goto out;
  84
  85                 if (type == T10_PI_TYPE3_PROTECTION)
  86                         bi.tag_size = sizeof(u16) + sizeof(u32);
  87                 else
  88                         bi.tag_size = sizeof(u16);
  89
  90                 sd_printk(KERN_NOTICE, sdkp, "DIF application tag size %u\n",
  91                           bi.tag_size);
  92         }
  93
  94 out:
  95         blk_integrity_register(disk, &bi);
  96 }
  97
  98 /*
  99  * The virtual start sector is the one that was originally submitted
 100  * by the block layer.  Due to partitioning, MD/DM cloning, etc. the
 101  * actual physical start sector is likely to be different.  Remap
 102  * protection information to match the physical LBA.
 103  *
 104  * From a protocol perspective there's a slight difference between
 105  * Type 1 and 2.  The latter uses 32-byte CDBs exclusively, and the
 106  * reference tag is seeded in the CDB.  This gives us the potential to
 107  * avoid virt->phys remapping during write.  However, at read time we
 108  * don't know whether the virt sector is the same as when we wrote it
 109  * (we could be reading from real disk as opposed to MD/DM device.  So
 110  * we always remap Type 2 making it identical to Type 1.
 111  *
 112  * Type 3 does not have a reference tag so no remapping is required.
 113  */
 114 void sd_dif_prepare(struct scsi_cmnd *scmd)
 115 {
 116         const int tuple_sz = sizeof(struct t10_pi_tuple);
 117         struct bio *bio;
 118         struct scsi_disk *sdkp;
 119         struct t10_pi_tuple *pi;
 120         u32 phys, virt;
 121
 122         sdkp = scsi_disk(scmd->request->rq_disk);
 123
 124         if (sdkp->protection_type == T10_PI_TYPE3_PROTECTION)
 125                 return;
 126
 127         phys = scsi_prot_ref_tag(scmd);
 128
 129         __rq_for_each_bio(bio, scmd->request) {
 130                 struct bio_integrity_payload *bip = bio_integrity(bio);
 131                 struct bio_vec iv;
 132                 struct bvec_iter iter;
 133                 unsigned int j;
 134
 135                 /* Already remapped? */
 136                 if (bip->bip_flags & BIP_MAPPED_INTEGRITY)
 137                         break;
 138
 139                 virt = bip_get_seed(bip) & 0xffffffff;
 140
 141                 bip_for_each_vec(iv, bip, iter) {
 142                         pi = kmap_atomic(iv.bv_page) + iv.bv_offset;
 143
 144                         for (j = 0; j < iv.bv_len; j += tuple_sz, pi++) {
 145
 146                                 if (be32_to_cpu(pi->ref_tag) == virt)
 147                                         pi->ref_tag = cpu_to_be32(phys);
 148
 149                                 virt++;
 150                                 phys++;
 151                         }
 152
 153                         kunmap_atomic(pi);
 154                 }
 155
 156                 bip->bip_flags |= BIP_MAPPED_INTEGRITY;
 157         }
 158 }
 159
 160 /*
 161  * Remap physical sector values in the reference tag to the virtual
 162  * values expected by the block layer.
 163  */
 164 void sd_dif_complete(struct scsi_cmnd *scmd, unsigned int good_bytes)
 165 {
 166         const int tuple_sz = sizeof(struct t10_pi_tuple);
 167         struct scsi_disk *sdkp;
 168         struct bio *bio;
 169         struct t10_pi_tuple *pi;
 170         unsigned int j, intervals;
 171         u32 phys, virt;
 172
 173         sdkp = scsi_disk(scmd->request->rq_disk);
 174
 175         if (sdkp->protection_type == T10_PI_TYPE3_PROTECTION || good_bytes == 0)
 176                 return;
 177
 178         intervals = good_bytes / scsi_prot_interval(scmd);
 179         phys = scsi_prot_ref_tag(scmd);
 180
 181         __rq_for_each_bio(bio, scmd->request) {
 182                 struct bio_integrity_payload *bip = bio_integrity(bio);
 183                 struct bio_vec iv;
 184                 struct bvec_iter iter;
 185
 186                 virt = bip_get_seed(bip) & 0xffffffff;
 187
 188                 bip_for_each_vec(iv, bip, iter) {
 189                         pi = kmap_atomic(iv.bv_page) + iv.bv_offset;
 190
 191                         for (j = 0; j < iv.bv_len; j += tuple_sz, pi++) {
 192
 193                                 if (intervals == 0) {
 194                                         kunmap_atomic(pi);
 195                                         return;
 196                                 }
 197
 198                                 if (be32_to_cpu(pi->ref_tag) == phys)
 199                                         pi->ref_tag = cpu_to_be32(virt);
 200
 201                                 virt++;
 202                                 phys++;
 203                                 intervals--;
 204                         }
 205
 206                         kunmap_atomic(pi);
 207                 }
 208         }
 209 }
 210