[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>

1 files changed, 538 insertions, 0 deletions

diff --git a/drivers/scsi/sd_dif.c b/drivers/scsi/sd_dif.c
new file mode 100644
index 000000000000..4d17f3d35aac
--- /dev/null
+++ b/drivers/scsi/sd_dif.c
@@ -0,0 +1,538 @@
+/*
+ * sd_dif.c - SCSI Data Integrity Field
+ *
+ * Copyright (C) 2007, 2008 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/blkdev.h>
+#include <linux/crc-t10dif.h>
+
+#include <scsi/scsi.h>
+#include <scsi/scsi_cmnd.h>
+#include <scsi/scsi_dbg.h>
+#include <scsi/scsi_device.h>
+#include <scsi/scsi_driver.h>
+#include <scsi/scsi_eh.h>
+#include <scsi/scsi_host.h>
+#include <scsi/scsi_ioctl.h>
+#include <scsi/scsicam.h>
+
+#include <net/checksum.h>
+
+#include "sd.h"
+
+typedef __u16 (csum_fn) (void *, unsigned int);
+
+static __u16 sd_dif_crc_fn(void *data, unsigned int len)
+{
+        return cpu_to_be16(crc_t10dif(data, len));
+}
+
+static __u16 sd_dif_ip_fn(void *data, unsigned int len)
+{
+        return 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.
+ */
+static void sd_dif_type1_generate(struct blk_integrity_exchg *bix, csum_fn *fn)
+{
+        void *buf = bix->data_buf;
+        struct sd_dif_tuple *sdt = bix->prot_buf;
+        sector_t sector = bix->sector;
+        unsigned int i;
+
+        for (i = 0 ; i < bix->data_size ; i += bix->sector_size, sdt++) {
+                sdt->guard_tag = fn(buf, bix->sector_size);
+                sdt->ref_tag = cpu_to_be32(sector & 0xffffffff);
+                sdt->app_tag = 0;
+
+                buf += bix->sector_size;
+                sector++;
+        }
+}
+
+static void sd_dif_type1_generate_crc(struct blk_integrity_exchg *bix)
+{
+        sd_dif_type1_generate(bix, sd_dif_crc_fn);
+}
+
+static void sd_dif_type1_generate_ip(struct blk_integrity_exchg *bix)
+{
+        sd_dif_type1_generate(bix, sd_dif_ip_fn);
+}
+
+static int sd_dif_type1_verify(struct blk_integrity_exchg *bix, csum_fn *fn)
+{
+        void *buf = bix->data_buf;
+        struct sd_dif_tuple *sdt = bix->prot_buf;
+        sector_t sector = bix->sector;
+        unsigned int i;
+        __u16 csum;
+
+        for (i = 0 ; i < bix->data_size ; i += bix->sector_size, sdt++) {
+                /* Unwritten sectors */
+                if (sdt->app_tag == 0xffff)
+                        return 0;
+
+                /* Bad ref tag received from disk */
+                if (sdt->ref_tag == 0xffffffff) {
+                        printk(KERN_ERR
+                               "%s: bad phys ref tag on sector %lu\n",
+                               bix->disk_name, (unsigned long)sector);
+                        return -EIO;
+                }
+
+                if (be32_to_cpu(sdt->ref_tag) != (sector & 0xffffffff)) {
+                        printk(KERN_ERR
+                               "%s: ref tag error on sector %lu (rcvd %u)\n",
+                               bix->disk_name, (unsigned long)sector,
+                               be32_to_cpu(sdt->ref_tag));
+                        return -EIO;
+                }
+
+                csum = fn(buf, bix->sector_size);
+
+                if (sdt->guard_tag != csum) {
+                        printk(KERN_ERR "%s: guard tag error on sector %lu " \
+                               "(rcvd %04x, data %04x)\n", bix->disk_name,
+                               (unsigned long)sector,
+                               be16_to_cpu(sdt->guard_tag), be16_to_cpu(csum));
+                        return -EIO;
+                }
+
+                buf += bix->sector_size;
+                sector++;
+        }
+
+        return 0;
+}
+
+static int sd_dif_type1_verify_crc(struct blk_integrity_exchg *bix)
+{
+        return sd_dif_type1_verify(bix, sd_dif_crc_fn);
+}
+
+static int sd_dif_type1_verify_ip(struct blk_integrity_exchg *bix)
+{
+        return sd_dif_type1_verify(bix, sd_dif_ip_fn);
+}
+
+/*
+ * Functions for interleaving and deinterleaving application tags
+ */
+static void sd_dif_type1_set_tag(void *prot, void *tag_buf, unsigned int sectors)
+{
+        struct sd_dif_tuple *sdt = prot;
+        char *tag = tag_buf;
+        unsigned int i, j;
+
+        for (i = 0, j = 0 ; i < sectors ; i++, j += 2, sdt++) {
+                sdt->app_tag = tag[j] << 8 | tag[j+1];
+                BUG_ON(sdt->app_tag == 0xffff);
+        }
+}
+
+static void sd_dif_type1_get_tag(void *prot, void *tag_buf, unsigned int sectors)
+{
+        struct sd_dif_tuple *sdt = prot;
+        char *tag = tag_buf;
+        unsigned int i, j;
+
+        for (i = 0, j = 0 ; i < sectors ; i++, j += 2, sdt++) {
+                tag[j] = (sdt->app_tag & 0xff00) >> 8;
+                tag[j+1] = sdt->app_tag & 0xff;
+        }
+}
+
+static struct blk_integrity dif_type1_integrity_crc = {
+        .name                   = "T10-DIF-TYPE1-CRC",
+        .generate_fn            = sd_dif_type1_generate_crc,
+        .verify_fn              = sd_dif_type1_verify_crc,
+        .get_tag_fn             = sd_dif_type1_get_tag,
+        .set_tag_fn             = sd_dif_type1_set_tag,
+        .tuple_size             = sizeof(struct sd_dif_tuple),
+        .tag_size               = 0,
+};
+
+static struct blk_integrity dif_type1_integrity_ip = {
+        .name                   = "T10-DIF-TYPE1-IP",
+        .generate_fn            = sd_dif_type1_generate_ip,
+        .verify_fn              = sd_dif_type1_verify_ip,
+        .get_tag_fn             = sd_dif_type1_get_tag,
+        .set_tag_fn             = sd_dif_type1_set_tag,
+        .tuple_size             = sizeof(struct sd_dif_tuple),
+        .tag_size               = 0,
+};
+
+
+/*
+ * Type 3 protection has a 16-bit guard tag and 16 + 32 bits of opaque
+ * tag space.
+ */
+static void sd_dif_type3_generate(struct blk_integrity_exchg *bix, csum_fn *fn)
+{
+        void *buf = bix->data_buf;
+        struct sd_dif_tuple *sdt = bix->prot_buf;
+        unsigned int i;
+
+        for (i = 0 ; i < bix->data_size ; i += bix->sector_size, sdt++) {
+                sdt->guard_tag = fn(buf, bix->sector_size);
+                sdt->ref_tag = 0;
+                sdt->app_tag = 0;
+
+                buf += bix->sector_size;
+        }
+}
+
+static void sd_dif_type3_generate_crc(struct blk_integrity_exchg *bix)
+{
+        sd_dif_type3_generate(bix, sd_dif_crc_fn);
+}
+
+static void sd_dif_type3_generate_ip(struct blk_integrity_exchg *bix)
+{
+        sd_dif_type3_generate(bix, sd_dif_ip_fn);
+}
+
+static int sd_dif_type3_verify(struct blk_integrity_exchg *bix, csum_fn *fn)
+{
+        void *buf = bix->data_buf;
+        struct sd_dif_tuple *sdt = bix->prot_buf;
+        sector_t sector = bix->sector;
+        unsigned int i;
+        __u16 csum;
+
+        for (i = 0 ; i < bix->data_size ; i += bix->sector_size, sdt++) {
+                /* Unwritten sectors */
+                if (sdt->app_tag == 0xffff && sdt->ref_tag == 0xffffffff)
+                        return 0;
+
+                csum = fn(buf, bix->sector_size);
+
+                if (sdt->guard_tag != csum) {
+                        printk(KERN_ERR "%s: guard tag error on sector %lu " \
+                               "(rcvd %04x, data %04x)\n", bix->disk_name,
+                               (unsigned long)sector,
+                               be16_to_cpu(sdt->guard_tag), be16_to_cpu(csum));
+                        return -EIO;
+                }
+
+                buf += bix->sector_size;
+                sector++;
+        }
+
+        return 0;
+}
+
+static int sd_dif_type3_verify_crc(struct blk_integrity_exchg *bix)
+{
+        return sd_dif_type3_verify(bix, sd_dif_crc_fn);
+}
+
+static int sd_dif_type3_verify_ip(struct blk_integrity_exchg *bix)
+{
+        return sd_dif_type3_verify(bix, sd_dif_ip_fn);
+}
+
+static void sd_dif_type3_set_tag(void *prot, void *tag_buf, unsigned int sectors)
+{
+        struct sd_dif_tuple *sdt = prot;
+        char *tag = tag_buf;
+        unsigned int i, j;
+
+        for (i = 0, j = 0 ; i < sectors ; i++, j += 6, sdt++) {
+                sdt->app_tag = tag[j] << 8 | tag[j+1];
+                sdt->ref_tag = tag[j+2] << 24 | tag[j+3] << 16 |
+                        tag[j+4] << 8 | tag[j+5];
+        }
+}
+
+static void sd_dif_type3_get_tag(void *prot, void *tag_buf, unsigned int sectors)
+{
+        struct sd_dif_tuple *sdt = prot;
+        char *tag = tag_buf;
+        unsigned int i, j;
+
+        for (i = 0, j = 0 ; i < sectors ; i++, j += 2, sdt++) {
+                tag[j] = (sdt->app_tag & 0xff00) >> 8;
+                tag[j+1] = sdt->app_tag & 0xff;
+                tag[j+2] = (sdt->ref_tag & 0xff000000) >> 24;
+                tag[j+3] = (sdt->ref_tag & 0xff0000) >> 16;
+                tag[j+4] = (sdt->ref_tag & 0xff00) >> 8;
+                tag[j+5] = sdt->ref_tag & 0xff;
+                BUG_ON(sdt->app_tag == 0xffff || sdt->ref_tag == 0xffffffff);
+        }
+}
+
+static struct blk_integrity dif_type3_integrity_crc = {
+        .name                   = "T10-DIF-TYPE3-CRC",
+        .generate_fn            = sd_dif_type3_generate_crc,
+        .verify_fn              = sd_dif_type3_verify_crc,
+        .get_tag_fn             = sd_dif_type3_get_tag,
+        .set_tag_fn             = sd_dif_type3_set_tag,
+        .tuple_size             = sizeof(struct sd_dif_tuple),
+        .tag_size               = 0,
+};
+
+static struct blk_integrity dif_type3_integrity_ip = {
+        .name                   = "T10-DIF-TYPE3-IP",
+        .generate_fn            = sd_dif_type3_generate_ip,
+        .verify_fn              = sd_dif_type3_verify_ip,
+        .get_tag_fn             = sd_dif_type3_get_tag,
+        .set_tag_fn             = sd_dif_type3_set_tag,
+        .tuple_size             = sizeof(struct sd_dif_tuple),
+        .tag_size               = 0,
+};
+
+/*
+ * Configure exchange of protection information between OS and HBA.
+ */
+void sd_dif_config_host(struct scsi_disk *sdkp)
+{
+        struct scsi_device *sdp = sdkp->device;
+        struct gendisk *disk = sdkp->disk;
+        u8 type = sdkp->protection_type;
+
+        /* If this HBA doesn't support DIX, resort to normal I/O or DIF */
+        if (scsi_host_dix_capable(sdp->host, type) == 0) {
+
+                if (type == SD_DIF_TYPE0_PROTECTION)
+                        return;
+
+                if (scsi_host_dif_capable(sdp->host, type) == 0) {
+                        sd_printk(KERN_INFO, sdkp, "Type %d protection " \
+                                  "unsupported by HBA. Disabling DIF.\n", type);
+                        sdkp->protection_type = 0;
+                        return;
+                }
+
+                sd_printk(KERN_INFO, sdkp, "Enabling DIF Type %d protection\n",
+                          type);
+
+                return;
+        }
+
+        /* Enable DMA of protection information */
+        if (scsi_host_get_guard(sdkp->device->host) & SHOST_DIX_GUARD_IP)
+                if (type == SD_DIF_TYPE3_PROTECTION)
+                        blk_integrity_register(disk, &dif_type3_integrity_ip);
+                else
+                        blk_integrity_register(disk, &dif_type1_integrity_ip);
+        else
+                if (type == SD_DIF_TYPE3_PROTECTION)
+                        blk_integrity_register(disk, &dif_type3_integrity_crc);
+                else
+                        blk_integrity_register(disk, &dif_type1_integrity_crc);
+
+        sd_printk(KERN_INFO, sdkp,
+                  "Enabling %s integrity protection\n", disk->integrity->name);
+
+        /* Signal to block layer that we support sector tagging */
+        if (type && sdkp->ATO) {
+                if (type == SD_DIF_TYPE3_PROTECTION)
+                        disk->integrity->tag_size = sizeof(u16) + sizeof(u32);
+                else
+                        disk->integrity->tag_size = sizeof(u16);
+
+                sd_printk(KERN_INFO, sdkp, "DIF application tag size %u\n",
+                          disk->integrity->tag_size);
+        }
+}
+
+/*
+ * DIF DMA operation magic decoder ring.
+ */
+void sd_dif_op(struct scsi_cmnd *scmd, unsigned int dif, unsigned int dix)
+{
+        int csum_convert, prot_op;
+
+        prot_op = 0;
+
+        /* Convert checksum? */
+        if (scsi_host_get_guard(scmd->device->host) != SHOST_DIX_GUARD_CRC)
+                csum_convert = 1;
+        else
+                csum_convert = 0;
+
+        switch (scmd->cmnd[0]) {
+        case READ_10:
+        case READ_12:
+        case READ_16:
+                if (dif && dix)
+                        if (csum_convert)
+                                prot_op = SCSI_PROT_READ_CONVERT;
+                        else
+                                prot_op = SCSI_PROT_READ_PASS;
+                else if (dif && !dix)
+                        prot_op = SCSI_PROT_READ_STRIP;
+                else if (!dif && dix)
+                        prot_op = SCSI_PROT_READ_INSERT;
+
+                break;
+
+        case WRITE_10:
+        case WRITE_12:
+        case WRITE_16:
+                if (dif && dix)
+                        if (csum_convert)
+                                prot_op = SCSI_PROT_WRITE_CONVERT;
+                        else
+                                prot_op = SCSI_PROT_WRITE_PASS;
+                else if (dif && !dix)
+                        prot_op = SCSI_PROT_WRITE_INSERT;
+                else if (!dif && dix)
+                        prot_op = SCSI_PROT_WRITE_STRIP;
+
+                break;
+        }
+
+        scsi_set_prot_op(scmd, prot_op);
+        scsi_set_prot_type(scmd, dif);
+}
+
+/*
+ * The virtual start sector is the one that was originally submitted
+ * by the block layer.  Due to partitioning, MD/DM cloning, etc. the
+ * actual physical start sector is likely to be different.  Remap
+ * protection information to match the physical LBA.
+ *
+ * From a protocol perspective there's a slight difference between
+ * Type 1 and 2.  The latter uses 32-byte CDBs exclusively, and the
+ * reference tag is seeded in the CDB.  This gives us the potential to
+ * avoid virt->phys remapping during write.  However, at read time we
+ * don't know whether the virt sector is the same as when we wrote it
+ * (we could be reading from real disk as opposed to MD/DM device.  So
+ * we always remap Type 2 making it identical to Type 1.
+ *
+ * Type 3 does not have a reference tag so no remapping is required.
+ */
+int sd_dif_prepare(struct request *rq, sector_t hw_sector, unsigned int sector_sz)
+{
+        const int tuple_sz = sizeof(struct sd_dif_tuple);
+        struct bio *bio;
+        struct scsi_disk *sdkp;
+        struct sd_dif_tuple *sdt;
+        unsigned int i, j;
+        u32 phys, virt;
+
+        /* Already remapped? */
+        if (rq->cmd_flags & REQ_INTEGRITY)
+                return 0;
+
+        sdkp = rq->bio->bi_bdev->bd_disk->private_data;
+
+        if (sdkp->protection_type == SD_DIF_TYPE3_PROTECTION)
+                return 0;
+
+        rq->cmd_flags |= REQ_INTEGRITY;
+        phys = hw_sector & 0xffffffff;
+
+        __rq_for_each_bio(bio, rq) {
+                struct bio_vec *iv;
+
+                virt = bio->bi_integrity->bip_sector & 0xffffffff;
+
+                bip_for_each_vec(iv, bio->bi_integrity, i) {
+                        sdt = kmap_atomic(iv->bv_page, KM_USER0)
+                                + iv->bv_offset;
+
+                        for (j = 0 ; j < iv->bv_len ; j += tuple_sz, sdt++) {
+
+                                if (be32_to_cpu(sdt->ref_tag) != virt)
+                                        goto error;
+
+                                sdt->ref_tag = cpu_to_be32(phys);
+                                virt++;
+                                phys++;
+                        }
+
+                        kunmap_atomic(sdt, KM_USER0);
+                }
+        }
+
+        return 0;
+
+error:
+        kunmap_atomic(sdt, KM_USER0);
+        sd_printk(KERN_ERR, sdkp, "%s: virt %u, phys %u, ref %u\n",
+                  __func__, virt, phys, be32_to_cpu(sdt->ref_tag));
+
+        return -EIO;
+}
+
+/*
+ * Remap physical sector values in the reference tag to the virtual
+ * values expected by the block layer.
+ */
+void sd_dif_complete(struct scsi_cmnd *scmd, unsigned int good_bytes)
+{
+        const int tuple_sz = sizeof(struct sd_dif_tuple);
+        struct scsi_disk *sdkp;
+        struct bio *bio;
+        struct sd_dif_tuple *sdt;
+        unsigned int i, j, sectors, sector_sz;
+        u32 phys, virt;
+
+        sdkp = scsi_disk(scmd->request->rq_disk);
+
+        if (sdkp->protection_type == SD_DIF_TYPE3_PROTECTION || good_bytes == 0)
+                return;
+
+        sector_sz = scmd->device->sector_size;
+        sectors = good_bytes / sector_sz;
+
+        phys = scmd->request->sector & 0xffffffff;
+        if (sector_sz == 4096)
+                phys >>= 3;
+
+        __rq_for_each_bio(bio, scmd->request) {
+                struct bio_vec *iv;
+
+                virt = bio->bi_integrity->bip_sector & 0xffffffff;
+
+                bip_for_each_vec(iv, bio->bi_integrity, i) {
+                        sdt = kmap_atomic(iv->bv_page, KM_USER0)
+                                + iv->bv_offset;
+
+                        for (j = 0 ; j < iv->bv_len ; j += tuple_sz, sdt++) {
+
+                                if (sectors == 0) {
+                                        kunmap_atomic(sdt, KM_USER0);
+                                        return;
+                                }
+
+                                if (be32_to_cpu(sdt->ref_tag) != phys &&
+                                    sdt->app_tag != 0xffff)
+                                        sdt->ref_tag = 0xffffffff; /* Bad ref */
+                                else
+                                        sdt->ref_tag = cpu_to_be32(virt);
+
+                                virt++;
+                                phys++;
+                                sectors--;
+                        }
+
+                        kunmap_atomic(sdt, KM_USER0);
+                }
+        }
+}
+