Merge tag 'scsi-misc' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi

[sfrench/cifs-2.6.git] / drivers / scsi / sd.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 *      sd.c Copyright (C) 1992 Drew Eckhardt
 *           Copyright (C) 1993, 1994, 1995, 1999 Eric Youngdale
 *
 *      Linux scsi disk driver
 *              Initial versions: Drew Eckhardt
 *              Subsequent revisions: Eric Youngdale
 *      Modification history:
 *       - Drew Eckhardt <drew@colorado.edu> original
 *       - Eric Youngdale <eric@andante.org> add scatter-gather, multiple 
 *         outstanding request, and other enhancements.
 *         Support loadable low-level scsi drivers.
 *       - Jirka Hanika <geo@ff.cuni.cz> support more scsi disks using 
 *         eight major numbers.
 *       - Richard Gooch <rgooch@atnf.csiro.au> support devfs.
 *       - Torben Mathiasen <tmm@image.dk> Resource allocation fixes in 
 *         sd_init and cleanups.
 *       - Alex Davis <letmein@erols.com> Fix problem where partition info
 *         not being read in sd_open. Fix problem where removable media 
 *         could be ejected after sd_open.
 *       - Douglas Gilbert <dgilbert@interlog.com> cleanup for lk 2.5.x
 *       - Badari Pulavarty <pbadari@us.ibm.com>, Matthew Wilcox 
 *         <willy@debian.org>, Kurt Garloff <garloff@suse.de>: 
 *         Support 32k/1M disks.
 *
 *      Logging policy (needs CONFIG_SCSI_LOGGING defined):
 *       - setting up transfer: SCSI_LOG_HLQUEUE levels 1 and 2
 *       - end of transfer (bh + scsi_lib): SCSI_LOG_HLCOMPLETE level 1
 *       - entering sd_ioctl: SCSI_LOG_IOCTL level 1
 *       - entering other commands: SCSI_LOG_HLQUEUE level 3
 *      Note: when the logging level is set by the user, it must be greater
 *      than the level indicated above to trigger output.       
 */

#include <linux/module.h>
#include <linux/fs.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/bio.h>
#include <linux/hdreg.h>
#include <linux/errno.h>
#include <linux/idr.h>
#include <linux/interrupt.h>
#include <linux/init.h>
#include <linux/blkdev.h>
#include <linux/blkpg.h>
#include <linux/blk-pm.h>
#include <linux/delay.h>
#include <linux/major.h>
#include <linux/mutex.h>
#include <linux/string_helpers.h>
#include <linux/slab.h>
#include <linux/sed-opal.h>
#include <linux/pm_runtime.h>
#include <linux/pr.h>
#include <linux/t10-pi.h>
#include <linux/uaccess.h>
#include <asm/unaligned.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 <scsi/scsi_common.h>

#include "sd.h"
#include "scsi_priv.h"
#include "scsi_logging.h"

MODULE_AUTHOR("Eric Youngdale");
MODULE_DESCRIPTION("SCSI disk (sd) driver");
MODULE_LICENSE("GPL");

MODULE_ALIAS_BLOCKDEV_MAJOR(SCSI_DISK0_MAJOR);
MODULE_ALIAS_BLOCKDEV_MAJOR(SCSI_DISK1_MAJOR);
MODULE_ALIAS_BLOCKDEV_MAJOR(SCSI_DISK2_MAJOR);
MODULE_ALIAS_BLOCKDEV_MAJOR(SCSI_DISK3_MAJOR);
MODULE_ALIAS_BLOCKDEV_MAJOR(SCSI_DISK4_MAJOR);
MODULE_ALIAS_BLOCKDEV_MAJOR(SCSI_DISK5_MAJOR);
MODULE_ALIAS_BLOCKDEV_MAJOR(SCSI_DISK6_MAJOR);
MODULE_ALIAS_BLOCKDEV_MAJOR(SCSI_DISK7_MAJOR);
MODULE_ALIAS_BLOCKDEV_MAJOR(SCSI_DISK8_MAJOR);
MODULE_ALIAS_BLOCKDEV_MAJOR(SCSI_DISK9_MAJOR);
MODULE_ALIAS_BLOCKDEV_MAJOR(SCSI_DISK10_MAJOR);
MODULE_ALIAS_BLOCKDEV_MAJOR(SCSI_DISK11_MAJOR);
MODULE_ALIAS_BLOCKDEV_MAJOR(SCSI_DISK12_MAJOR);
MODULE_ALIAS_BLOCKDEV_MAJOR(SCSI_DISK13_MAJOR);
MODULE_ALIAS_BLOCKDEV_MAJOR(SCSI_DISK14_MAJOR);
MODULE_ALIAS_BLOCKDEV_MAJOR(SCSI_DISK15_MAJOR);
MODULE_ALIAS_SCSI_DEVICE(TYPE_DISK);
MODULE_ALIAS_SCSI_DEVICE(TYPE_MOD);
MODULE_ALIAS_SCSI_DEVICE(TYPE_RBC);
MODULE_ALIAS_SCSI_DEVICE(TYPE_ZBC);

#define SD_MINORS       16

static void sd_config_discard(struct scsi_disk *, unsigned int);
static void sd_config_write_same(struct scsi_disk *);
static int  sd_revalidate_disk(struct gendisk *);
static void sd_unlock_native_capacity(struct gendisk *disk);
static void sd_shutdown(struct device *);
static void sd_read_capacity(struct scsi_disk *sdkp, unsigned char *buffer);
static void scsi_disk_release(struct device *cdev);

static DEFINE_IDA(sd_index_ida);

static mempool_t *sd_page_pool;
static struct lock_class_key sd_bio_compl_lkclass;

static const char *sd_cache_types[] = {
        "write through", "none", "write back",
        "write back, no read (daft)"
};

static void sd_set_flush_flag(struct scsi_disk *sdkp)
{
        bool wc = false, fua = false;

        if (sdkp->WCE) {
                wc = true;
                if (sdkp->DPOFUA)
                        fua = true;
        }

        blk_queue_write_cache(sdkp->disk->queue, wc, fua);
}

static ssize_t
cache_type_store(struct device *dev, struct device_attribute *attr,
                 const char *buf, size_t count)
{
        int ct, rcd, wce, sp;
        struct scsi_disk *sdkp = to_scsi_disk(dev);
        struct scsi_device *sdp = sdkp->device;
        char buffer[64];
        char *buffer_data;
        struct scsi_mode_data data;
        struct scsi_sense_hdr sshdr;
        static const char temp[] = "temporary ";
        int len;

        if (sdp->type != TYPE_DISK && sdp->type != TYPE_ZBC)
                /* no cache control on RBC devices; theoretically they
                 * can do it, but there's probably so many exceptions
                 * it's not worth the risk */
                return -EINVAL;

        if (strncmp(buf, temp, sizeof(temp) - 1) == 0) {
                buf += sizeof(temp) - 1;
                sdkp->cache_override = 1;
        } else {
                sdkp->cache_override = 0;
        }

        ct = sysfs_match_string(sd_cache_types, buf);
        if (ct < 0)
                return -EINVAL;

        rcd = ct & 0x01 ? 1 : 0;
        wce = (ct & 0x02) && !sdkp->write_prot ? 1 : 0;

        if (sdkp->cache_override) {
                sdkp->WCE = wce;
                sdkp->RCD = rcd;
                sd_set_flush_flag(sdkp);
                return count;
        }

        if (scsi_mode_sense(sdp, 0x08, 8, 0, buffer, sizeof(buffer), SD_TIMEOUT,
                            sdkp->max_retries, &data, NULL))
                return -EINVAL;
        len = min_t(size_t, sizeof(buffer), data.length - data.header_length -
                  data.block_descriptor_length);
        buffer_data = buffer + data.header_length +
                data.block_descriptor_length;
        buffer_data[2] &= ~0x05;
        buffer_data[2] |= wce << 2 | rcd;
        sp = buffer_data[0] & 0x80 ? 1 : 0;
        buffer_data[0] &= ~0x80;

        /*
         * Ensure WP, DPOFUA, and RESERVED fields are cleared in
         * received mode parameter buffer before doing MODE SELECT.
         */
        data.device_specific = 0;

        if (scsi_mode_select(sdp, 1, sp, buffer_data, len, SD_TIMEOUT,
                             sdkp->max_retries, &data, &sshdr)) {
                if (scsi_sense_valid(&sshdr))
                        sd_print_sense_hdr(sdkp, &sshdr);
                return -EINVAL;
        }
        sd_revalidate_disk(sdkp->disk);
        return count;
}

static ssize_t
manage_start_stop_show(struct device *dev, struct device_attribute *attr,
                       char *buf)
{
        struct scsi_disk *sdkp = to_scsi_disk(dev);
        struct scsi_device *sdp = sdkp->device;

        return sprintf(buf, "%u\n", sdp->manage_start_stop);
}

static ssize_t
manage_start_stop_store(struct device *dev, struct device_attribute *attr,
                        const char *buf, size_t count)
{
        struct scsi_disk *sdkp = to_scsi_disk(dev);
        struct scsi_device *sdp = sdkp->device;
        bool v;

        if (!capable(CAP_SYS_ADMIN))
                return -EACCES;

        if (kstrtobool(buf, &v))
                return -EINVAL;

        sdp->manage_start_stop = v;

        return count;
}
static DEVICE_ATTR_RW(manage_start_stop);

static ssize_t
allow_restart_show(struct device *dev, struct device_attribute *attr, char *buf)
{
        struct scsi_disk *sdkp = to_scsi_disk(dev);

        return sprintf(buf, "%u\n", sdkp->device->allow_restart);
}

static ssize_t
allow_restart_store(struct device *dev, struct device_attribute *attr,
                    const char *buf, size_t count)
{
        bool v;
        struct scsi_disk *sdkp = to_scsi_disk(dev);
        struct scsi_device *sdp = sdkp->device;

        if (!capable(CAP_SYS_ADMIN))
                return -EACCES;

        if (sdp->type != TYPE_DISK && sdp->type != TYPE_ZBC)
                return -EINVAL;

        if (kstrtobool(buf, &v))
                return -EINVAL;

        sdp->allow_restart = v;

        return count;
}
static DEVICE_ATTR_RW(allow_restart);

static ssize_t
cache_type_show(struct device *dev, struct device_attribute *attr, char *buf)
{
        struct scsi_disk *sdkp = to_scsi_disk(dev);
        int ct = sdkp->RCD + 2*sdkp->WCE;

        return sprintf(buf, "%s\n", sd_cache_types[ct]);
}
static DEVICE_ATTR_RW(cache_type);

static ssize_t
FUA_show(struct device *dev, struct device_attribute *attr, char *buf)
{
        struct scsi_disk *sdkp = to_scsi_disk(dev);

        return sprintf(buf, "%u\n", sdkp->DPOFUA);
}
static DEVICE_ATTR_RO(FUA);

static ssize_t
protection_type_show(struct device *dev, struct device_attribute *attr,
                     char *buf)
{
        struct scsi_disk *sdkp = to_scsi_disk(dev);

        return sprintf(buf, "%u\n", sdkp->protection_type);
}

static ssize_t
protection_type_store(struct device *dev, struct device_attribute *attr,
                      const char *buf, size_t count)
{
        struct scsi_disk *sdkp = to_scsi_disk(dev);
        unsigned int val;
        int err;

        if (!capable(CAP_SYS_ADMIN))
                return -EACCES;

        err = kstrtouint(buf, 10, &val);

        if (err)
                return err;

        if (val <= T10_PI_TYPE3_PROTECTION)
                sdkp->protection_type = val;

        return count;
}
static DEVICE_ATTR_RW(protection_type);

static ssize_t
protection_mode_show(struct device *dev, struct device_attribute *attr,
                     char *buf)
{
        struct scsi_disk *sdkp = to_scsi_disk(dev);
        struct scsi_device *sdp = sdkp->device;
        unsigned int dif, dix;

        dif = scsi_host_dif_capable(sdp->host, sdkp->protection_type);
        dix = scsi_host_dix_capable(sdp->host, sdkp->protection_type);

        if (!dix && scsi_host_dix_capable(sdp->host, T10_PI_TYPE0_PROTECTION)) {
                dif = 0;
                dix = 1;
        }

        if (!dif && !dix)
                return sprintf(buf, "none\n");

        return sprintf(buf, "%s%u\n", dix ? "dix" : "dif", dif);
}
static DEVICE_ATTR_RO(protection_mode);

static ssize_t
app_tag_own_show(struct device *dev, struct device_attribute *attr, char *buf)
{
        struct scsi_disk *sdkp = to_scsi_disk(dev);

        return sprintf(buf, "%u\n", sdkp->ATO);
}
static DEVICE_ATTR_RO(app_tag_own);

static ssize_t
thin_provisioning_show(struct device *dev, struct device_attribute *attr,
                       char *buf)
{
        struct scsi_disk *sdkp = to_scsi_disk(dev);

        return sprintf(buf, "%u\n", sdkp->lbpme);
}
static DEVICE_ATTR_RO(thin_provisioning);

/* sysfs_match_string() requires dense arrays */
static const char *lbp_mode[] = {
        [SD_LBP_FULL]           = "full",
        [SD_LBP_UNMAP]          = "unmap",
        [SD_LBP_WS16]           = "writesame_16",
        [SD_LBP_WS10]           = "writesame_10",
        [SD_LBP_ZERO]           = "writesame_zero",
        [SD_LBP_DISABLE]        = "disabled",
};

static ssize_t
provisioning_mode_show(struct device *dev, struct device_attribute *attr,
                       char *buf)
{
        struct scsi_disk *sdkp = to_scsi_disk(dev);

        return sprintf(buf, "%s\n", lbp_mode[sdkp->provisioning_mode]);
}

static ssize_t
provisioning_mode_store(struct device *dev, struct device_attribute *attr,
                        const char *buf, size_t count)
{
        struct scsi_disk *sdkp = to_scsi_disk(dev);
        struct scsi_device *sdp = sdkp->device;
        int mode;

        if (!capable(CAP_SYS_ADMIN))
                return -EACCES;

        if (sd_is_zoned(sdkp)) {
                sd_config_discard(sdkp, SD_LBP_DISABLE);
                return count;
        }

        if (sdp->type != TYPE_DISK)
                return -EINVAL;

        mode = sysfs_match_string(lbp_mode, buf);
        if (mode < 0)
                return -EINVAL;

        sd_config_discard(sdkp, mode);

        return count;
}
static DEVICE_ATTR_RW(provisioning_mode);

/* sysfs_match_string() requires dense arrays */
static const char *zeroing_mode[] = {
        [SD_ZERO_WRITE]         = "write",
        [SD_ZERO_WS]            = "writesame",
        [SD_ZERO_WS16_UNMAP]    = "writesame_16_unmap",
        [SD_ZERO_WS10_UNMAP]    = "writesame_10_unmap",
};

static ssize_t
zeroing_mode_show(struct device *dev, struct device_attribute *attr,
                  char *buf)
{
        struct scsi_disk *sdkp = to_scsi_disk(dev);

        return sprintf(buf, "%s\n", zeroing_mode[sdkp->zeroing_mode]);
}

static ssize_t
zeroing_mode_store(struct device *dev, struct device_attribute *attr,
                   const char *buf, size_t count)
{
        struct scsi_disk *sdkp = to_scsi_disk(dev);
        int mode;

        if (!capable(CAP_SYS_ADMIN))
                return -EACCES;

        mode = sysfs_match_string(zeroing_mode, buf);
        if (mode < 0)
                return -EINVAL;

        sdkp->zeroing_mode = mode;

        return count;
}
static DEVICE_ATTR_RW(zeroing_mode);

static ssize_t
max_medium_access_timeouts_show(struct device *dev,
                                struct device_attribute *attr, char *buf)
{
        struct scsi_disk *sdkp = to_scsi_disk(dev);

        return sprintf(buf, "%u\n", sdkp->max_medium_access_timeouts);
}

static ssize_t
max_medium_access_timeouts_store(struct device *dev,
                                 struct device_attribute *attr, const char *buf,
                                 size_t count)
{
        struct scsi_disk *sdkp = to_scsi_disk(dev);
        int err;

        if (!capable(CAP_SYS_ADMIN))
                return -EACCES;

        err = kstrtouint(buf, 10, &sdkp->max_medium_access_timeouts);

        return err ? err : count;
}
static DEVICE_ATTR_RW(max_medium_access_timeouts);

static ssize_t
max_write_same_blocks_show(struct device *dev, struct device_attribute *attr,
                           char *buf)
{
        struct scsi_disk *sdkp = to_scsi_disk(dev);

        return sprintf(buf, "%u\n", sdkp->max_ws_blocks);
}

static ssize_t
max_write_same_blocks_store(struct device *dev, struct device_attribute *attr,
                            const char *buf, size_t count)
{
        struct scsi_disk *sdkp = to_scsi_disk(dev);
        struct scsi_device *sdp = sdkp->device;
        unsigned long max;
        int err;

        if (!capable(CAP_SYS_ADMIN))
                return -EACCES;

        if (sdp->type != TYPE_DISK && sdp->type != TYPE_ZBC)
                return -EINVAL;

        err = kstrtoul(buf, 10, &max);

        if (err)
                return err;

        if (max == 0)
                sdp->no_write_same = 1;
        else if (max <= SD_MAX_WS16_BLOCKS) {
                sdp->no_write_same = 0;
                sdkp->max_ws_blocks = max;
        }

        sd_config_write_same(sdkp);

        return count;
}
static DEVICE_ATTR_RW(max_write_same_blocks);

static ssize_t
zoned_cap_show(struct device *dev, struct device_attribute *attr, char *buf)
{
        struct scsi_disk *sdkp = to_scsi_disk(dev);

        if (sdkp->device->type == TYPE_ZBC)
                return sprintf(buf, "host-managed\n");
        if (sdkp->zoned == 1)
                return sprintf(buf, "host-aware\n");
        if (sdkp->zoned == 2)
                return sprintf(buf, "drive-managed\n");
        return sprintf(buf, "none\n");
}
static DEVICE_ATTR_RO(zoned_cap);

static ssize_t
max_retries_store(struct device *dev, struct device_attribute *attr,
                  const char *buf, size_t count)
{
        struct scsi_disk *sdkp = to_scsi_disk(dev);
        struct scsi_device *sdev = sdkp->device;
        int retries, err;

        err = kstrtoint(buf, 10, &retries);
        if (err)
                return err;

        if (retries == SCSI_CMD_RETRIES_NO_LIMIT || retries <= SD_MAX_RETRIES) {
                sdkp->max_retries = retries;
                return count;
        }

        sdev_printk(KERN_ERR, sdev, "max_retries must be between -1 and %d\n",
                    SD_MAX_RETRIES);
        return -EINVAL;
}

static ssize_t
max_retries_show(struct device *dev, struct device_attribute *attr,
                 char *buf)
{
        struct scsi_disk *sdkp = to_scsi_disk(dev);

        return sprintf(buf, "%d\n", sdkp->max_retries);
}

static DEVICE_ATTR_RW(max_retries);

static struct attribute *sd_disk_attrs[] = {
        &dev_attr_cache_type.attr,
        &dev_attr_FUA.attr,
        &dev_attr_allow_restart.attr,
        &dev_attr_manage_start_stop.attr,
        &dev_attr_protection_type.attr,
        &dev_attr_protection_mode.attr,
        &dev_attr_app_tag_own.attr,
        &dev_attr_thin_provisioning.attr,
        &dev_attr_provisioning_mode.attr,
        &dev_attr_zeroing_mode.attr,
        &dev_attr_max_write_same_blocks.attr,
        &dev_attr_max_medium_access_timeouts.attr,
        &dev_attr_zoned_cap.attr,
        &dev_attr_max_retries.attr,
        NULL,
};
ATTRIBUTE_GROUPS(sd_disk);

static struct class sd_disk_class = {
        .name           = "scsi_disk",
        .dev_release    = scsi_disk_release,
        .dev_groups     = sd_disk_groups,
};

/*
 * Don't request a new module, as that could deadlock in multipath
 * environment.
 */
static void sd_default_probe(dev_t devt)
{
}

/*
 * Device no to disk mapping:
 * 
 *       major         disc2     disc  p1
 *   |............|.............|....|....| <- dev_t
 *    31        20 19          8 7  4 3  0
 * 
 * Inside a major, we have 16k disks, however mapped non-
 * contiguously. The first 16 disks are for major0, the next
 * ones with major1, ... Disk 256 is for major0 again, disk 272 
 * for major1, ... 
 * As we stay compatible with our numbering scheme, we can reuse 
 * the well-know SCSI majors 8, 65--71, 136--143.
 */
static int sd_major(int major_idx)
{
        switch (major_idx) {
        case 0:
                return SCSI_DISK0_MAJOR;
        case 1 ... 7:
                return SCSI_DISK1_MAJOR + major_idx - 1;
        case 8 ... 15:
                return SCSI_DISK8_MAJOR + major_idx - 8;
        default:
                BUG();
                return 0;       /* shut up gcc */
        }
}

#ifdef CONFIG_BLK_SED_OPAL
static int sd_sec_submit(void *data, u16 spsp, u8 secp, void *buffer,
                size_t len, bool send)
{
        struct scsi_disk *sdkp = data;
        struct scsi_device *sdev = sdkp->device;
        u8 cdb[12] = { 0, };
        const struct scsi_exec_args exec_args = {
                .req_flags = BLK_MQ_REQ_PM,
        };
        int ret;

        cdb[0] = send ? SECURITY_PROTOCOL_OUT : SECURITY_PROTOCOL_IN;
        cdb[1] = secp;
        put_unaligned_be16(spsp, &cdb[2]);
        put_unaligned_be32(len, &cdb[6]);

        ret = scsi_execute_cmd(sdev, cdb, send ? REQ_OP_DRV_OUT : REQ_OP_DRV_IN,
                               buffer, len, SD_TIMEOUT, sdkp->max_retries,
                               &exec_args);
        return ret <= 0 ? ret : -EIO;
}
#endif /* CONFIG_BLK_SED_OPAL */

/*
 * Look up the DIX operation based on whether the command is read or
 * write and whether dix and dif are enabled.
 */
static unsigned int sd_prot_op(bool write, bool dix, bool dif)
{
        /* Lookup table: bit 2 (write), bit 1 (dix), bit 0 (dif) */
        static const unsigned int ops[] = {     /* wrt dix dif */
                SCSI_PROT_NORMAL,               /*  0   0   0  */
                SCSI_PROT_READ_STRIP,           /*  0   0   1  */
                SCSI_PROT_READ_INSERT,          /*  0   1   0  */
                SCSI_PROT_READ_PASS,            /*  0   1   1  */
                SCSI_PROT_NORMAL,               /*  1   0   0  */
                SCSI_PROT_WRITE_INSERT,         /*  1   0   1  */
                SCSI_PROT_WRITE_STRIP,          /*  1   1   0  */
                SCSI_PROT_WRITE_PASS,           /*  1   1   1  */
        };

        return ops[write << 2 | dix << 1 | dif];
}

/*
 * Returns a mask of the protection flags that are valid for a given DIX
 * operation.
 */
static unsigned int sd_prot_flag_mask(unsigned int prot_op)
{
        static const unsigned int flag_mask[] = {
                [SCSI_PROT_NORMAL]              = 0,

                [SCSI_PROT_READ_STRIP]          = SCSI_PROT_TRANSFER_PI |
                                                  SCSI_PROT_GUARD_CHECK |
                                                  SCSI_PROT_REF_CHECK |
                                                  SCSI_PROT_REF_INCREMENT,

                [SCSI_PROT_READ_INSERT]         = SCSI_PROT_REF_INCREMENT |
                                                  SCSI_PROT_IP_CHECKSUM,

                [SCSI_PROT_READ_PASS]           = SCSI_PROT_TRANSFER_PI |
                                                  SCSI_PROT_GUARD_CHECK |
                                                  SCSI_PROT_REF_CHECK |
                                                  SCSI_PROT_REF_INCREMENT |
                                                  SCSI_PROT_IP_CHECKSUM,

                [SCSI_PROT_WRITE_INSERT]        = SCSI_PROT_TRANSFER_PI |
                                                  SCSI_PROT_REF_INCREMENT,

                [SCSI_PROT_WRITE_STRIP]         = SCSI_PROT_GUARD_CHECK |
                                                  SCSI_PROT_REF_CHECK |
                                                  SCSI_PROT_REF_INCREMENT |
                                                  SCSI_PROT_IP_CHECKSUM,

                [SCSI_PROT_WRITE_PASS]          = SCSI_PROT_TRANSFER_PI |
                                                  SCSI_PROT_GUARD_CHECK |
                                                  SCSI_PROT_REF_CHECK |
                                                  SCSI_PROT_REF_INCREMENT |
                                                  SCSI_PROT_IP_CHECKSUM,
        };

        return flag_mask[prot_op];
}

static unsigned char sd_setup_protect_cmnd(struct scsi_cmnd *scmd,
                                           unsigned int dix, unsigned int dif)
{
        struct request *rq = scsi_cmd_to_rq(scmd);
        struct bio *bio = rq->bio;
        unsigned int prot_op = sd_prot_op(rq_data_dir(rq), dix, dif);
        unsigned int protect = 0;

        if (dix) {                              /* DIX Type 0, 1, 2, 3 */
                if (bio_integrity_flagged(bio, BIP_IP_CHECKSUM))
                        scmd->prot_flags |= SCSI_PROT_IP_CHECKSUM;

                if (bio_integrity_flagged(bio, BIP_CTRL_NOCHECK) == false)
                        scmd->prot_flags |= SCSI_PROT_GUARD_CHECK;
        }

        if (dif != T10_PI_TYPE3_PROTECTION) {   /* DIX/DIF Type 0, 1, 2 */
                scmd->prot_flags |= SCSI_PROT_REF_INCREMENT;

                if (bio_integrity_flagged(bio, BIP_CTRL_NOCHECK) == false)
                        scmd->prot_flags |= SCSI_PROT_REF_CHECK;
        }

        if (dif) {                              /* DIX/DIF Type 1, 2, 3 */
                scmd->prot_flags |= SCSI_PROT_TRANSFER_PI;

                if (bio_integrity_flagged(bio, BIP_DISK_NOCHECK))
                        protect = 3 << 5;       /* Disable target PI checking */
                else
                        protect = 1 << 5;       /* Enable target PI checking */
        }

        scsi_set_prot_op(scmd, prot_op);
        scsi_set_prot_type(scmd, dif);
        scmd->prot_flags &= sd_prot_flag_mask(prot_op);

        return protect;
}

static void sd_config_discard(struct scsi_disk *sdkp, unsigned int mode)
{
        struct request_queue *q = sdkp->disk->queue;
        unsigned int logical_block_size = sdkp->device->sector_size;
        unsigned int max_blocks = 0;

        q->limits.discard_alignment =
                sdkp->unmap_alignment * logical_block_size;
        q->limits.discard_granularity =
                max(sdkp->physical_block_size,
                    sdkp->unmap_granularity * logical_block_size);
        sdkp->provisioning_mode = mode;

        switch (mode) {

        case SD_LBP_FULL:
        case SD_LBP_DISABLE:
                blk_queue_max_discard_sectors(q, 0);
                return;

        case SD_LBP_UNMAP:
                max_blocks = min_not_zero(sdkp->max_unmap_blocks,
                                          (u32)SD_MAX_WS16_BLOCKS);
                break;

        case SD_LBP_WS16:
                if (sdkp->device->unmap_limit_for_ws)
                        max_blocks = sdkp->max_unmap_blocks;
                else
                        max_blocks = sdkp->max_ws_blocks;

                max_blocks = min_not_zero(max_blocks, (u32)SD_MAX_WS16_BLOCKS);
                break;

        case SD_LBP_WS10:
                if (sdkp->device->unmap_limit_for_ws)
                        max_blocks = sdkp->max_unmap_blocks;
                else
                        max_blocks = sdkp->max_ws_blocks;

                max_blocks = min_not_zero(max_blocks, (u32)SD_MAX_WS10_BLOCKS);
                break;

        case SD_LBP_ZERO:
                max_blocks = min_not_zero(sdkp->max_ws_blocks,
                                          (u32)SD_MAX_WS10_BLOCKS);
                break;
        }

        blk_queue_max_discard_sectors(q, max_blocks * (logical_block_size >> 9));
}

static void *sd_set_special_bvec(struct request *rq, unsigned int data_len)
{
        struct page *page;

        page = mempool_alloc(sd_page_pool, GFP_ATOMIC);
        if (!page)
                return NULL;
        clear_highpage(page);
        bvec_set_page(&rq->special_vec, page, data_len, 0);
        rq->rq_flags |= RQF_SPECIAL_PAYLOAD;
        return bvec_virt(&rq->special_vec);
}

static blk_status_t sd_setup_unmap_cmnd(struct scsi_cmnd *cmd)
{
        struct scsi_device *sdp = cmd->device;
        struct request *rq = scsi_cmd_to_rq(cmd);
        struct scsi_disk *sdkp = scsi_disk(rq->q->disk);
        u64 lba = sectors_to_logical(sdp, blk_rq_pos(rq));
        u32 nr_blocks = sectors_to_logical(sdp, blk_rq_sectors(rq));
        unsigned int data_len = 24;
        char *buf;

        buf = sd_set_special_bvec(rq, data_len);
        if (!buf)
                return BLK_STS_RESOURCE;

        cmd->cmd_len = 10;
        cmd->cmnd[0] = UNMAP;
        cmd->cmnd[8] = 24;

        put_unaligned_be16(6 + 16, &buf[0]);
        put_unaligned_be16(16, &buf[2]);
        put_unaligned_be64(lba, &buf[8]);
        put_unaligned_be32(nr_blocks, &buf[16]);

        cmd->allowed = sdkp->max_retries;
        cmd->transfersize = data_len;
        rq->timeout = SD_TIMEOUT;

        return scsi_alloc_sgtables(cmd);
}

static blk_status_t sd_setup_write_same16_cmnd(struct scsi_cmnd *cmd,
                bool unmap)
{
        struct scsi_device *sdp = cmd->device;
        struct request *rq = scsi_cmd_to_rq(cmd);
        struct scsi_disk *sdkp = scsi_disk(rq->q->disk);
        u64 lba = sectors_to_logical(sdp, blk_rq_pos(rq));
        u32 nr_blocks = sectors_to_logical(sdp, blk_rq_sectors(rq));
        u32 data_len = sdp->sector_size;

        if (!sd_set_special_bvec(rq, data_len))
                return BLK_STS_RESOURCE;

        cmd->cmd_len = 16;
        cmd->cmnd[0] = WRITE_SAME_16;
        if (unmap)
                cmd->cmnd[1] = 0x8; /* UNMAP */
        put_unaligned_be64(lba, &cmd->cmnd[2]);
        put_unaligned_be32(nr_blocks, &cmd->cmnd[10]);

        cmd->allowed = sdkp->max_retries;
        cmd->transfersize = data_len;
        rq->timeout = unmap ? SD_TIMEOUT : SD_WRITE_SAME_TIMEOUT;

        return scsi_alloc_sgtables(cmd);
}

static blk_status_t sd_setup_write_same10_cmnd(struct scsi_cmnd *cmd,
                bool unmap)
{
        struct scsi_device *sdp = cmd->device;
        struct request *rq = scsi_cmd_to_rq(cmd);
        struct scsi_disk *sdkp = scsi_disk(rq->q->disk);
        u64 lba = sectors_to_logical(sdp, blk_rq_pos(rq));
        u32 nr_blocks = sectors_to_logical(sdp, blk_rq_sectors(rq));
        u32 data_len = sdp->sector_size;

        if (!sd_set_special_bvec(rq, data_len))
                return BLK_STS_RESOURCE;

        cmd->cmd_len = 10;
        cmd->cmnd[0] = WRITE_SAME;
        if (unmap)
                cmd->cmnd[1] = 0x8; /* UNMAP */
        put_unaligned_be32(lba, &cmd->cmnd[2]);
        put_unaligned_be16(nr_blocks, &cmd->cmnd[7]);

        cmd->allowed = sdkp->max_retries;
        cmd->transfersize = data_len;
        rq->timeout = unmap ? SD_TIMEOUT : SD_WRITE_SAME_TIMEOUT;

        return scsi_alloc_sgtables(cmd);
}

static blk_status_t sd_setup_write_zeroes_cmnd(struct scsi_cmnd *cmd)
{
        struct request *rq = scsi_cmd_to_rq(cmd);
        struct scsi_device *sdp = cmd->device;
        struct scsi_disk *sdkp = scsi_disk(rq->q->disk);
        u64 lba = sectors_to_logical(sdp, blk_rq_pos(rq));
        u32 nr_blocks = sectors_to_logical(sdp, blk_rq_sectors(rq));

        if (!(rq->cmd_flags & REQ_NOUNMAP)) {
                switch (sdkp->zeroing_mode) {
                case SD_ZERO_WS16_UNMAP:
                        return sd_setup_write_same16_cmnd(cmd, true);
                case SD_ZERO_WS10_UNMAP:
                        return sd_setup_write_same10_cmnd(cmd, true);
                }
        }

        if (sdp->no_write_same) {
                rq->rq_flags |= RQF_QUIET;
                return BLK_STS_TARGET;
        }

        if (sdkp->ws16 || lba > 0xffffffff || nr_blocks > 0xffff)
                return sd_setup_write_same16_cmnd(cmd, false);

        return sd_setup_write_same10_cmnd(cmd, false);
}

static void sd_config_write_same(struct scsi_disk *sdkp)
{
        struct request_queue *q = sdkp->disk->queue;
        unsigned int logical_block_size = sdkp->device->sector_size;

        if (sdkp->device->no_write_same) {
                sdkp->max_ws_blocks = 0;
                goto out;
        }

        /* Some devices can not handle block counts above 0xffff despite
         * supporting WRITE SAME(16). Consequently we default to 64k
         * blocks per I/O unless the device explicitly advertises a
         * bigger limit.
         */
        if (sdkp->max_ws_blocks > SD_MAX_WS10_BLOCKS)
                sdkp->max_ws_blocks = min_not_zero(sdkp->max_ws_blocks,
                                                   (u32)SD_MAX_WS16_BLOCKS);
        else if (sdkp->ws16 || sdkp->ws10 || sdkp->device->no_report_opcodes)
                sdkp->max_ws_blocks = min_not_zero(sdkp->max_ws_blocks,
                                                   (u32)SD_MAX_WS10_BLOCKS);
        else {
                sdkp->device->no_write_same = 1;
                sdkp->max_ws_blocks = 0;
        }

        if (sdkp->lbprz && sdkp->lbpws)
                sdkp->zeroing_mode = SD_ZERO_WS16_UNMAP;
        else if (sdkp->lbprz && sdkp->lbpws10)
                sdkp->zeroing_mode = SD_ZERO_WS10_UNMAP;
        else if (sdkp->max_ws_blocks)
                sdkp->zeroing_mode = SD_ZERO_WS;
        else
                sdkp->zeroing_mode = SD_ZERO_WRITE;

        if (sdkp->max_ws_blocks &&
            sdkp->physical_block_size > logical_block_size) {
                /*
                 * Reporting a maximum number of blocks that is not aligned
                 * on the device physical size would cause a large write same
                 * request to be split into physically unaligned chunks by
                 * __blkdev_issue_write_zeroes() even if the caller of this
                 * functions took care to align the large request. So make sure
                 * the maximum reported is aligned to the device physical block
                 * size. This is only an optional optimization for regular
                 * disks, but this is mandatory to avoid failure of large write
                 * same requests directed at sequential write required zones of
                 * host-managed ZBC disks.
                 */
                sdkp->max_ws_blocks =
                        round_down(sdkp->max_ws_blocks,
                                   bytes_to_logical(sdkp->device,
                                                    sdkp->physical_block_size));
        }

out:
        blk_queue_max_write_zeroes_sectors(q, sdkp->max_ws_blocks *
                                         (logical_block_size >> 9));
}

static blk_status_t sd_setup_flush_cmnd(struct scsi_cmnd *cmd)
{
        struct request *rq = scsi_cmd_to_rq(cmd);
        struct scsi_disk *sdkp = scsi_disk(rq->q->disk);

        /* flush requests don't perform I/O, zero the S/G table */
        memset(&cmd->sdb, 0, sizeof(cmd->sdb));

        if (cmd->device->use_16_for_sync) {
                cmd->cmnd[0] = SYNCHRONIZE_CACHE_16;
                cmd->cmd_len = 16;
        } else {
                cmd->cmnd[0] = SYNCHRONIZE_CACHE;
                cmd->cmd_len = 10;
        }
        cmd->transfersize = 0;
        cmd->allowed = sdkp->max_retries;

        rq->timeout = rq->q->rq_timeout * SD_FLUSH_TIMEOUT_MULTIPLIER;
        return BLK_STS_OK;
}

static blk_status_t sd_setup_rw32_cmnd(struct scsi_cmnd *cmd, bool write,
                                       sector_t lba, unsigned int nr_blocks,
                                       unsigned char flags, unsigned int dld)
{
        cmd->cmd_len = SD_EXT_CDB_SIZE;
        cmd->cmnd[0]  = VARIABLE_LENGTH_CMD;
        cmd->cmnd[7]  = 0x18; /* Additional CDB len */
        cmd->cmnd[9]  = write ? WRITE_32 : READ_32;
        cmd->cmnd[10] = flags;
        cmd->cmnd[11] = dld & 0x07;
        put_unaligned_be64(lba, &cmd->cmnd[12]);
        put_unaligned_be32(lba, &cmd->cmnd[20]); /* Expected Indirect LBA */
        put_unaligned_be32(nr_blocks, &cmd->cmnd[28]);

        return BLK_STS_OK;
}

static blk_status_t sd_setup_rw16_cmnd(struct scsi_cmnd *cmd, bool write,
                                       sector_t lba, unsigned int nr_blocks,
                                       unsigned char flags, unsigned int dld)
{
        cmd->cmd_len  = 16;
        cmd->cmnd[0]  = write ? WRITE_16 : READ_16;
        cmd->cmnd[1]  = flags | ((dld >> 2) & 0x01);
        cmd->cmnd[14] = (dld & 0x03) << 6;
        cmd->cmnd[15] = 0;
        put_unaligned_be64(lba, &cmd->cmnd[2]);
        put_unaligned_be32(nr_blocks, &cmd->cmnd[10]);

        return BLK_STS_OK;
}

static blk_status_t sd_setup_rw10_cmnd(struct scsi_cmnd *cmd, bool write,
                                       sector_t lba, unsigned int nr_blocks,
                                       unsigned char flags)
{
        cmd->cmd_len = 10;
        cmd->cmnd[0] = write ? WRITE_10 : READ_10;
        cmd->cmnd[1] = flags;
        cmd->cmnd[6] = 0;
        cmd->cmnd[9] = 0;
        put_unaligned_be32(lba, &cmd->cmnd[2]);
        put_unaligned_be16(nr_blocks, &cmd->cmnd[7]);

        return BLK_STS_OK;
}

static blk_status_t sd_setup_rw6_cmnd(struct scsi_cmnd *cmd, bool write,
                                      sector_t lba, unsigned int nr_blocks,
                                      unsigned char flags)
{
        /* Avoid that 0 blocks gets translated into 256 blocks. */
        if (WARN_ON_ONCE(nr_blocks == 0))
                return BLK_STS_IOERR;

        if (unlikely(flags & 0x8)) {
                /*
                 * This happens only if this drive failed 10byte rw
                 * command with ILLEGAL_REQUEST during operation and
                 * thus turned off use_10_for_rw.
                 */
                scmd_printk(KERN_ERR, cmd, "FUA write on READ/WRITE(6) drive\n");
                return BLK_STS_IOERR;
        }

        cmd->cmd_len = 6;
        cmd->cmnd[0] = write ? WRITE_6 : READ_6;
        cmd->cmnd[1] = (lba >> 16) & 0x1f;
        cmd->cmnd[2] = (lba >> 8) & 0xff;
        cmd->cmnd[3] = lba & 0xff;
        cmd->cmnd[4] = nr_blocks;
        cmd->cmnd[5] = 0;

        return BLK_STS_OK;
}

/*
 * Check if a command has a duration limit set. If it does, and the target
 * device supports CDL and the feature is enabled, return the limit
 * descriptor index to use. Return 0 (no limit) otherwise.
 */
static int sd_cdl_dld(struct scsi_disk *sdkp, struct scsi_cmnd *scmd)
{
        struct scsi_device *sdp = sdkp->device;
        int hint;

        if (!sdp->cdl_supported || !sdp->cdl_enable)
                return 0;

        /*
         * Use "no limit" if the request ioprio does not specify a duration
         * limit hint.
         */
        hint = IOPRIO_PRIO_HINT(req_get_ioprio(scsi_cmd_to_rq(scmd)));
        if (hint < IOPRIO_HINT_DEV_DURATION_LIMIT_1 ||
            hint > IOPRIO_HINT_DEV_DURATION_LIMIT_7)
                return 0;

        return (hint - IOPRIO_HINT_DEV_DURATION_LIMIT_1) + 1;
}

static blk_status_t sd_setup_read_write_cmnd(struct scsi_cmnd *cmd)
{
        struct request *rq = scsi_cmd_to_rq(cmd);
        struct scsi_device *sdp = cmd->device;
        struct scsi_disk *sdkp = scsi_disk(rq->q->disk);
        sector_t lba = sectors_to_logical(sdp, blk_rq_pos(rq));
        sector_t threshold;
        unsigned int nr_blocks = sectors_to_logical(sdp, blk_rq_sectors(rq));
        unsigned int mask = logical_to_sectors(sdp, 1) - 1;
        bool write = rq_data_dir(rq) == WRITE;
        unsigned char protect, fua;
        unsigned int dld;
        blk_status_t ret;
        unsigned int dif;
        bool dix;

        ret = scsi_alloc_sgtables(cmd);
        if (ret != BLK_STS_OK)
                return ret;

        ret = BLK_STS_IOERR;
        if (!scsi_device_online(sdp) || sdp->changed) {
                scmd_printk(KERN_ERR, cmd, "device offline or changed\n");
                goto fail;
        }

        if (blk_rq_pos(rq) + blk_rq_sectors(rq) > get_capacity(rq->q->disk)) {
                scmd_printk(KERN_ERR, cmd, "access beyond end of device\n");
                goto fail;
        }

        if ((blk_rq_pos(rq) & mask) || (blk_rq_sectors(rq) & mask)) {
                scmd_printk(KERN_ERR, cmd, "request not aligned to the logical block size\n");
                goto fail;
        }

        /*
         * Some SD card readers can't handle accesses which touch the
         * last one or two logical blocks. Split accesses as needed.
         */
        threshold = sdkp->capacity - SD_LAST_BUGGY_SECTORS;

        if (unlikely(sdp->last_sector_bug && lba + nr_blocks > threshold)) {
                if (lba < threshold) {
                        /* Access up to the threshold but not beyond */
                        nr_blocks = threshold - lba;
                } else {
                        /* Access only a single logical block */
                        nr_blocks = 1;
                }
        }

        if (req_op(rq) == REQ_OP_ZONE_APPEND) {
                ret = sd_zbc_prepare_zone_append(cmd, &lba, nr_blocks);
                if (ret)
                        goto fail;
        }

        fua = rq->cmd_flags & REQ_FUA ? 0x8 : 0;
        dix = scsi_prot_sg_count(cmd);
        dif = scsi_host_dif_capable(cmd->device->host, sdkp->protection_type);
        dld = sd_cdl_dld(sdkp, cmd);

        if (dif || dix)
                protect = sd_setup_protect_cmnd(cmd, dix, dif);
        else
                protect = 0;

        if (protect && sdkp->protection_type == T10_PI_TYPE2_PROTECTION) {
                ret = sd_setup_rw32_cmnd(cmd, write, lba, nr_blocks,
                                         protect | fua, dld);
        } else if (sdp->use_16_for_rw || (nr_blocks > 0xffff)) {
                ret = sd_setup_rw16_cmnd(cmd, write, lba, nr_blocks,
                                         protect | fua, dld);
        } else if ((nr_blocks > 0xff) || (lba > 0x1fffff) ||
                   sdp->use_10_for_rw || protect) {
                ret = sd_setup_rw10_cmnd(cmd, write, lba, nr_blocks,
                                         protect | fua);
        } else {
                ret = sd_setup_rw6_cmnd(cmd, write, lba, nr_blocks,
                                        protect | fua);
        }

        if (unlikely(ret != BLK_STS_OK))
                goto fail;

        /*
         * We shouldn't disconnect in the middle of a sector, so with a dumb
         * host adapter, it's safe to assume that we can at least transfer
         * this many bytes between each connect / disconnect.
         */
        cmd->transfersize = sdp->sector_size;
        cmd->underflow = nr_blocks << 9;
        cmd->allowed = sdkp->max_retries;
        cmd->sdb.length = nr_blocks * sdp->sector_size;

        SCSI_LOG_HLQUEUE(1,
                         scmd_printk(KERN_INFO, cmd,
                                     "%s: block=%llu, count=%d\n", __func__,
                                     (unsigned long long)blk_rq_pos(rq),
                                     blk_rq_sectors(rq)));
        SCSI_LOG_HLQUEUE(2,
                         scmd_printk(KERN_INFO, cmd,
                                     "%s %d/%u 512 byte blocks.\n",
                                     write ? "writing" : "reading", nr_blocks,
                                     blk_rq_sectors(rq)));

        /*
         * This indicates that the command is ready from our end to be queued.
         */
        return BLK_STS_OK;
fail:
        scsi_free_sgtables(cmd);
        return ret;
}

static blk_status_t sd_init_command(struct scsi_cmnd *cmd)
{
        struct request *rq = scsi_cmd_to_rq(cmd);

        switch (req_op(rq)) {
        case REQ_OP_DISCARD:
                switch (scsi_disk(rq->q->disk)->provisioning_mode) {
                case SD_LBP_UNMAP:
                        return sd_setup_unmap_cmnd(cmd);
                case SD_LBP_WS16:
                        return sd_setup_write_same16_cmnd(cmd, true);
                case SD_LBP_WS10:
                        return sd_setup_write_same10_cmnd(cmd, true);
                case SD_LBP_ZERO:
                        return sd_setup_write_same10_cmnd(cmd, false);
                default:
                        return BLK_STS_TARGET;
                }
        case REQ_OP_WRITE_ZEROES:
                return sd_setup_write_zeroes_cmnd(cmd);
        case REQ_OP_FLUSH:
                return sd_setup_flush_cmnd(cmd);
        case REQ_OP_READ:
        case REQ_OP_WRITE:
        case REQ_OP_ZONE_APPEND:
                return sd_setup_read_write_cmnd(cmd);
        case REQ_OP_ZONE_RESET:
                return sd_zbc_setup_zone_mgmt_cmnd(cmd, ZO_RESET_WRITE_POINTER,
                                                   false);
        case REQ_OP_ZONE_RESET_ALL:
                return sd_zbc_setup_zone_mgmt_cmnd(cmd, ZO_RESET_WRITE_POINTER,
                                                   true);
        case REQ_OP_ZONE_OPEN:
                return sd_zbc_setup_zone_mgmt_cmnd(cmd, ZO_OPEN_ZONE, false);
        case REQ_OP_ZONE_CLOSE:
                return sd_zbc_setup_zone_mgmt_cmnd(cmd, ZO_CLOSE_ZONE, false);
        case REQ_OP_ZONE_FINISH:
                return sd_zbc_setup_zone_mgmt_cmnd(cmd, ZO_FINISH_ZONE, false);
        default:
                WARN_ON_ONCE(1);
                return BLK_STS_NOTSUPP;
        }
}

static void sd_uninit_command(struct scsi_cmnd *SCpnt)
{
        struct request *rq = scsi_cmd_to_rq(SCpnt);

        if (rq->rq_flags & RQF_SPECIAL_PAYLOAD)
                mempool_free(rq->special_vec.bv_page, sd_page_pool);
}

static bool sd_need_revalidate(struct gendisk *disk, struct scsi_disk *sdkp)
{
        if (sdkp->device->removable || sdkp->write_prot) {
                if (disk_check_media_change(disk))
                        return true;
        }

        /*
         * Force a full rescan after ioctl(BLKRRPART).  While the disk state has
         * nothing to do with partitions, BLKRRPART is used to force a full
         * revalidate after things like a format for historical reasons.
         */
        return test_bit(GD_NEED_PART_SCAN, &disk->state);
}

/**
 *      sd_open - open a scsi disk device
 *      @disk: disk to open
 *      @mode: open mode
 *
 *      Returns 0 if successful. Returns a negated errno value in case 
 *      of error.
 *
 *      Note: This can be called from a user context (e.g. fsck(1) )
 *      or from within the kernel (e.g. as a result of a mount(1) ).
 *      In the latter case @inode and @filp carry an abridged amount
 *      of information as noted above.
 *
 *      Locking: called with disk->open_mutex held.
 **/
static int sd_open(struct gendisk *disk, blk_mode_t mode)
{
        struct scsi_disk *sdkp = scsi_disk(disk);
        struct scsi_device *sdev = sdkp->device;
        int retval;

        if (scsi_device_get(sdev))
                return -ENXIO;

        SCSI_LOG_HLQUEUE(3, sd_printk(KERN_INFO, sdkp, "sd_open\n"));

        /*
         * If the device is in error recovery, wait until it is done.
         * If the device is offline, then disallow any access to it.
         */
        retval = -ENXIO;
        if (!scsi_block_when_processing_errors(sdev))
                goto error_out;

        if (sd_need_revalidate(disk, sdkp))
                sd_revalidate_disk(disk);

        /*
         * If the drive is empty, just let the open fail.
         */
        retval = -ENOMEDIUM;
        if (sdev->removable && !sdkp->media_present &&
            !(mode & BLK_OPEN_NDELAY))
                goto error_out;

        /*
         * If the device has the write protect tab set, have the open fail
         * if the user expects to be able to write to the thing.
         */
        retval = -EROFS;
        if (sdkp->write_prot && (mode & BLK_OPEN_WRITE))
                goto error_out;

        /*
         * It is possible that the disk changing stuff resulted in
         * the device being taken offline.  If this is the case,
         * report this to the user, and don't pretend that the
         * open actually succeeded.
         */
        retval = -ENXIO;
        if (!scsi_device_online(sdev))
                goto error_out;

        if ((atomic_inc_return(&sdkp->openers) == 1) && sdev->removable) {
                if (scsi_block_when_processing_errors(sdev))
                        scsi_set_medium_removal(sdev, SCSI_REMOVAL_PREVENT);
        }

        return 0;

error_out:
        scsi_device_put(sdev);
        return retval;  
}

/**
 *      sd_release - invoked when the (last) close(2) is called on this
 *      scsi disk.
 *      @disk: disk to release
 *
 *      Returns 0. 
 *
 *      Note: may block (uninterruptible) if error recovery is underway
 *      on this disk.
 *
 *      Locking: called with disk->open_mutex held.
 **/
static void sd_release(struct gendisk *disk)
{
        struct scsi_disk *sdkp = scsi_disk(disk);
        struct scsi_device *sdev = sdkp->device;

        SCSI_LOG_HLQUEUE(3, sd_printk(KERN_INFO, sdkp, "sd_release\n"));

        if (atomic_dec_return(&sdkp->openers) == 0 && sdev->removable) {
                if (scsi_block_when_processing_errors(sdev))
                        scsi_set_medium_removal(sdev, SCSI_REMOVAL_ALLOW);
        }

        scsi_device_put(sdev);
}

static int sd_getgeo(struct block_device *bdev, struct hd_geometry *geo)
{
        struct scsi_disk *sdkp = scsi_disk(bdev->bd_disk);
        struct scsi_device *sdp = sdkp->device;
        struct Scsi_Host *host = sdp->host;
        sector_t capacity = logical_to_sectors(sdp, sdkp->capacity);
        int diskinfo[4];

        /* default to most commonly used values */
        diskinfo[0] = 0x40;     /* 1 << 6 */
        diskinfo[1] = 0x20;     /* 1 << 5 */
        diskinfo[2] = capacity >> 11;

        /* override with calculated, extended default, or driver values */
        if (host->hostt->bios_param)
                host->hostt->bios_param(sdp, bdev, capacity, diskinfo);
        else
                scsicam_bios_param(bdev, capacity, diskinfo);

        geo->heads = diskinfo[0];
        geo->sectors = diskinfo[1];
        geo->cylinders = diskinfo[2];
        return 0;
}

/**
 *      sd_ioctl - process an ioctl
 *      @bdev: target block device
 *      @mode: open mode
 *      @cmd: ioctl command number
 *      @arg: this is third argument given to ioctl(2) system call.
 *      Often contains a pointer.
 *
 *      Returns 0 if successful (some ioctls return positive numbers on
 *      success as well). Returns a negated errno value in case of error.
 *
 *      Note: most ioctls are forward onto the block subsystem or further
 *      down in the scsi subsystem.
 **/
static int sd_ioctl(struct block_device *bdev, blk_mode_t mode,
                    unsigned int cmd, unsigned long arg)
{
        struct gendisk *disk = bdev->bd_disk;
        struct scsi_disk *sdkp = scsi_disk(disk);
        struct scsi_device *sdp = sdkp->device;
        void __user *p = (void __user *)arg;
        int error;
    
        SCSI_LOG_IOCTL(1, sd_printk(KERN_INFO, sdkp, "sd_ioctl: disk=%s, "
                                    "cmd=0x%x\n", disk->disk_name, cmd));

        if (bdev_is_partition(bdev) && !capable(CAP_SYS_RAWIO))
                return -ENOIOCTLCMD;

        /*
         * If we are in the middle of error recovery, don't let anyone
         * else try and use this device.  Also, if error recovery fails, it
         * may try and take the device offline, in which case all further
         * access to the device is prohibited.
         */
        error = scsi_ioctl_block_when_processing_errors(sdp, cmd,
                        (mode & BLK_OPEN_NDELAY));
        if (error)
                return error;

        if (is_sed_ioctl(cmd))
                return sed_ioctl(sdkp->opal_dev, cmd, p);
        return scsi_ioctl(sdp, mode & BLK_OPEN_WRITE, cmd, p);
}

static void set_media_not_present(struct scsi_disk *sdkp)
{
        if (sdkp->media_present)
                sdkp->device->changed = 1;

        if (sdkp->device->removable) {
                sdkp->media_present = 0;
                sdkp->capacity = 0;
        }
}

static int media_not_present(struct scsi_disk *sdkp,
                             struct scsi_sense_hdr *sshdr)
{
        if (!scsi_sense_valid(sshdr))
                return 0;

        /* not invoked for commands that could return deferred errors */
        switch (sshdr->sense_key) {
        case UNIT_ATTENTION:
        case NOT_READY:
                /* medium not present */
                if (sshdr->asc == 0x3A) {
                        set_media_not_present(sdkp);
                        return 1;
                }
        }
        return 0;
}

/**
 *      sd_check_events - check media events
 *      @disk: kernel device descriptor
 *      @clearing: disk events currently being cleared
 *
 *      Returns mask of DISK_EVENT_*.
 *
 *      Note: this function is invoked from the block subsystem.
 **/
static unsigned int sd_check_events(struct gendisk *disk, unsigned int clearing)
{
        struct scsi_disk *sdkp = disk->private_data;
        struct scsi_device *sdp;
        int retval;
        bool disk_changed;

        if (!sdkp)
                return 0;

        sdp = sdkp->device;
        SCSI_LOG_HLQUEUE(3, sd_printk(KERN_INFO, sdkp, "sd_check_events\n"));

        /*
         * If the device is offline, don't send any commands - just pretend as
         * if the command failed.  If the device ever comes back online, we
         * can deal with it then.  It is only because of unrecoverable errors
         * that we would ever take a device offline in the first place.
         */
        if (!scsi_device_online(sdp)) {
                set_media_not_present(sdkp);
                goto out;
        }

        /*
         * Using TEST_UNIT_READY enables differentiation between drive with
         * no cartridge loaded - NOT READY, drive with changed cartridge -
         * UNIT ATTENTION, or with same cartridge - GOOD STATUS.
         *
         * Drives that auto spin down. eg iomega jaz 1G, will be started
         * by sd_spinup_disk() from sd_revalidate_disk(), which happens whenever
         * sd_revalidate() is called.
         */
        if (scsi_block_when_processing_errors(sdp)) {
                struct scsi_sense_hdr sshdr = { 0, };

                retval = scsi_test_unit_ready(sdp, SD_TIMEOUT, sdkp->max_retries,
                                              &sshdr);

                /* failed to execute TUR, assume media not present */
                if (retval < 0 || host_byte(retval)) {
                        set_media_not_present(sdkp);
                        goto out;
                }

                if (media_not_present(sdkp, &sshdr))
                        goto out;
        }

        /*
         * For removable scsi disk we have to recognise the presence
         * of a disk in the drive.
         */
        if (!sdkp->media_present)
                sdp->changed = 1;
        sdkp->media_present = 1;
out:
        /*
         * sdp->changed is set under the following conditions:
         *
         *      Medium present state has changed in either direction.
         *      Device has indicated UNIT_ATTENTION.
         */
        disk_changed = sdp->changed;
        sdp->changed = 0;
        return disk_changed ? DISK_EVENT_MEDIA_CHANGE : 0;
}

static int sd_sync_cache(struct scsi_disk *sdkp, struct scsi_sense_hdr *sshdr)
{
        int retries, res;
        struct scsi_device *sdp = sdkp->device;
        const int timeout = sdp->request_queue->rq_timeout
                * SD_FLUSH_TIMEOUT_MULTIPLIER;
        struct scsi_sense_hdr my_sshdr;
        const struct scsi_exec_args exec_args = {
                .req_flags = BLK_MQ_REQ_PM,
                /* caller might not be interested in sense, but we need it */
                .sshdr = sshdr ? : &my_sshdr,
        };

        if (!scsi_device_online(sdp))
                return -ENODEV;

        sshdr = exec_args.sshdr;

        for (retries = 3; retries > 0; --retries) {
                unsigned char cmd[16] = { 0 };

                if (sdp->use_16_for_sync)
                        cmd[0] = SYNCHRONIZE_CACHE_16;
                else
                        cmd[0] = SYNCHRONIZE_CACHE;
                /*
                 * Leave the rest of the command zero to indicate
                 * flush everything.
                 */
                res = scsi_execute_cmd(sdp, cmd, REQ_OP_DRV_IN, NULL, 0,
                                       timeout, sdkp->max_retries, &exec_args);
                if (res == 0)
                        break;
        }

        if (res) {
                sd_print_result(sdkp, "Synchronize Cache(10) failed", res);

                if (res < 0)
                        return res;

                if (scsi_status_is_check_condition(res) &&
                    scsi_sense_valid(sshdr)) {
                        sd_print_sense_hdr(sdkp, sshdr);

                        /* we need to evaluate the error return  */
                        if (sshdr->asc == 0x3a ||       /* medium not present */
                            sshdr->asc == 0x20 ||       /* invalid command */
                            (sshdr->asc == 0x74 && sshdr->ascq == 0x71))        /* drive is password locked */
                                /* this is no error here */
                                return 0;
                }

                switch (host_byte(res)) {
                /* ignore errors due to racing a disconnection */
                case DID_BAD_TARGET:
                case DID_NO_CONNECT:
                        return 0;
                /* signal the upper layer it might try again */
                case DID_BUS_BUSY:
                case DID_IMM_RETRY:
                case DID_REQUEUE:
                case DID_SOFT_ERROR:
                        return -EBUSY;
                default:
                        return -EIO;
                }
        }
        return 0;
}

static void sd_rescan(struct device *dev)
{
        struct scsi_disk *sdkp = dev_get_drvdata(dev);

        sd_revalidate_disk(sdkp->disk);
}

static int sd_get_unique_id(struct gendisk *disk, u8 id[16],
                enum blk_unique_id type)
{
        struct scsi_device *sdev = scsi_disk(disk)->device;
        const struct scsi_vpd *vpd;
        const unsigned char *d;
        int ret = -ENXIO, len;

        rcu_read_lock();
        vpd = rcu_dereference(sdev->vpd_pg83);
        if (!vpd)
                goto out_unlock;

        ret = -EINVAL;
        for (d = vpd->data + 4; d < vpd->data + vpd->len; d += d[3] + 4) {
                /* we only care about designators with LU association */
                if (((d[1] >> 4) & 0x3) != 0x00)
                        continue;
                if ((d[1] & 0xf) != type)
                        continue;

                /*
                 * Only exit early if a 16-byte descriptor was found.  Otherwise
                 * keep looking as one with more entropy might still show up.
                 */
                len = d[3];
                if (len != 8 && len != 12 && len != 16)
                        continue;
                ret = len;
                memcpy(id, d + 4, len);
                if (len == 16)
                        break;
        }
out_unlock:
        rcu_read_unlock();
        return ret;
}

static int sd_scsi_to_pr_err(struct scsi_sense_hdr *sshdr, int result)
{
        switch (host_byte(result)) {
        case DID_TRANSPORT_MARGINAL:
        case DID_TRANSPORT_DISRUPTED:
        case DID_BUS_BUSY:
                return PR_STS_RETRY_PATH_FAILURE;
        case DID_NO_CONNECT:
                return PR_STS_PATH_FAILED;
        case DID_TRANSPORT_FAILFAST:
                return PR_STS_PATH_FAST_FAILED;
        }

        switch (status_byte(result)) {
        case SAM_STAT_RESERVATION_CONFLICT:
                return PR_STS_RESERVATION_CONFLICT;
        case SAM_STAT_CHECK_CONDITION:
                if (!scsi_sense_valid(sshdr))
                        return PR_STS_IOERR;

                if (sshdr->sense_key == ILLEGAL_REQUEST &&
                    (sshdr->asc == 0x26 || sshdr->asc == 0x24))
                        return -EINVAL;

                fallthrough;
        default:
                return PR_STS_IOERR;
        }
}

static int sd_pr_in_command(struct block_device *bdev, u8 sa,
                            unsigned char *data, int data_len)
{
        struct scsi_disk *sdkp = scsi_disk(bdev->bd_disk);
        struct scsi_device *sdev = sdkp->device;
        struct scsi_sense_hdr sshdr;
        u8 cmd[10] = { PERSISTENT_RESERVE_IN, sa };
        const struct scsi_exec_args exec_args = {
                .sshdr = &sshdr,
        };
        int result;

        put_unaligned_be16(data_len, &cmd[7]);

        result = scsi_execute_cmd(sdev, cmd, REQ_OP_DRV_IN, data, data_len,
                                  SD_TIMEOUT, sdkp->max_retries, &exec_args);
        if (scsi_status_is_check_condition(result) &&
            scsi_sense_valid(&sshdr)) {
                sdev_printk(KERN_INFO, sdev, "PR command failed: %d\n", result);
                scsi_print_sense_hdr(sdev, NULL, &sshdr);
        }

        if (result <= 0)
                return result;

        return sd_scsi_to_pr_err(&sshdr, result);
}

static int sd_pr_read_keys(struct block_device *bdev, struct pr_keys *keys_info)
{
        int result, i, data_offset, num_copy_keys;
        u32 num_keys = keys_info->num_keys;
        int data_len = num_keys * 8 + 8;
        u8 *data;

        data = kzalloc(data_len, GFP_KERNEL);
        if (!data)
                return -ENOMEM;

        result = sd_pr_in_command(bdev, READ_KEYS, data, data_len);
        if (result)
                goto free_data;

        keys_info->generation = get_unaligned_be32(&data[0]);
        keys_info->num_keys = get_unaligned_be32(&data[4]) / 8;

        data_offset = 8;
        num_copy_keys = min(num_keys, keys_info->num_keys);

        for (i = 0; i < num_copy_keys; i++) {
                keys_info->keys[i] = get_unaligned_be64(&data[data_offset]);
                data_offset += 8;
        }

free_data:
        kfree(data);
        return result;
}

static int sd_pr_read_reservation(struct block_device *bdev,
                                  struct pr_held_reservation *rsv)
{
        struct scsi_disk *sdkp = scsi_disk(bdev->bd_disk);
        struct scsi_device *sdev = sdkp->device;
        u8 data[24] = { };
        int result, len;

        result = sd_pr_in_command(bdev, READ_RESERVATION, data, sizeof(data));
        if (result)
                return result;

        len = get_unaligned_be32(&data[4]);
        if (!len)
                return 0;

        /* Make sure we have at least the key and type */
        if (len < 14) {
                sdev_printk(KERN_INFO, sdev,
                            "READ RESERVATION failed due to short return buffer of %d bytes\n",
                            len);
                return -EINVAL;
        }

        rsv->generation = get_unaligned_be32(&data[0]);
        rsv->key = get_unaligned_be64(&data[8]);
        rsv->type = scsi_pr_type_to_block(data[21] & 0x0f);
        return 0;
}

static int sd_pr_out_command(struct block_device *bdev, u8 sa, u64 key,
                             u64 sa_key, enum scsi_pr_type type, u8 flags)
{
        struct scsi_disk *sdkp = scsi_disk(bdev->bd_disk);
        struct scsi_device *sdev = sdkp->device;
        struct scsi_sense_hdr sshdr;
        const struct scsi_exec_args exec_args = {
                .sshdr = &sshdr,
        };
        int result;
        u8 cmd[16] = { 0, };
        u8 data[24] = { 0, };

        cmd[0] = PERSISTENT_RESERVE_OUT;
        cmd[1] = sa;
        cmd[2] = type;
        put_unaligned_be32(sizeof(data), &cmd[5]);

        put_unaligned_be64(key, &data[0]);
        put_unaligned_be64(sa_key, &data[8]);
        data[20] = flags;

        result = scsi_execute_cmd(sdev, cmd, REQ_OP_DRV_OUT, &data,
                                  sizeof(data), SD_TIMEOUT, sdkp->max_retries,
                                  &exec_args);

        if (scsi_status_is_check_condition(result) &&
            scsi_sense_valid(&sshdr)) {
                sdev_printk(KERN_INFO, sdev, "PR command failed: %d\n", result);
                scsi_print_sense_hdr(sdev, NULL, &sshdr);
        }

        if (result <= 0)
                return result;

        return sd_scsi_to_pr_err(&sshdr, result);
}

static int sd_pr_register(struct block_device *bdev, u64 old_key, u64 new_key,
                u32 flags)
{
        if (flags & ~PR_FL_IGNORE_KEY)
                return -EOPNOTSUPP;
        return sd_pr_out_command(bdev, (flags & PR_FL_IGNORE_KEY) ? 0x06 : 0x00,
                        old_key, new_key, 0,
                        (1 << 0) /* APTPL */);
}

static int sd_pr_reserve(struct block_device *bdev, u64 key, enum pr_type type,
                u32 flags)
{
        if (flags)
                return -EOPNOTSUPP;
        return sd_pr_out_command(bdev, 0x01, key, 0,
                                 block_pr_type_to_scsi(type), 0);
}

static int sd_pr_release(struct block_device *bdev, u64 key, enum pr_type type)
{
        return sd_pr_out_command(bdev, 0x02, key, 0,
                                 block_pr_type_to_scsi(type), 0);
}

static int sd_pr_preempt(struct block_device *bdev, u64 old_key, u64 new_key,
                enum pr_type type, bool abort)
{
        return sd_pr_out_command(bdev, abort ? 0x05 : 0x04, old_key, new_key,
                                 block_pr_type_to_scsi(type), 0);
}

static int sd_pr_clear(struct block_device *bdev, u64 key)
{
        return sd_pr_out_command(bdev, 0x03, key, 0, 0, 0);
}

static const struct pr_ops sd_pr_ops = {
        .pr_register    = sd_pr_register,
        .pr_reserve     = sd_pr_reserve,
        .pr_release     = sd_pr_release,
        .pr_preempt     = sd_pr_preempt,
        .pr_clear       = sd_pr_clear,
        .pr_read_keys   = sd_pr_read_keys,
        .pr_read_reservation = sd_pr_read_reservation,
};

static void scsi_disk_free_disk(struct gendisk *disk)
{
        struct scsi_disk *sdkp = scsi_disk(disk);

        put_device(&sdkp->disk_dev);
}

static const struct block_device_operations sd_fops = {
        .owner                  = THIS_MODULE,
        .open                   = sd_open,
        .release                = sd_release,
        .ioctl                  = sd_ioctl,
        .getgeo                 = sd_getgeo,
        .compat_ioctl           = blkdev_compat_ptr_ioctl,
        .check_events           = sd_check_events,
        .unlock_native_capacity = sd_unlock_native_capacity,
        .report_zones           = sd_zbc_report_zones,
        .get_unique_id          = sd_get_unique_id,
        .free_disk              = scsi_disk_free_disk,
        .pr_ops                 = &sd_pr_ops,
};

/**
 *      sd_eh_reset - reset error handling callback
 *      @scmd:          sd-issued command that has failed
 *
 *      This function is called by the SCSI midlayer before starting
 *      SCSI EH. When counting medium access failures we have to be
 *      careful to register it only only once per device and SCSI EH run;
 *      there might be several timed out commands which will cause the
 *      'max_medium_access_timeouts' counter to trigger after the first
 *      SCSI EH run already and set the device to offline.
 *      So this function resets the internal counter before starting SCSI EH.
 **/
static void sd_eh_reset(struct scsi_cmnd *scmd)
{
        struct scsi_disk *sdkp = scsi_disk(scsi_cmd_to_rq(scmd)->q->disk);

        /* New SCSI EH run, reset gate variable */
        sdkp->ignore_medium_access_errors = false;
}

/**
 *      sd_eh_action - error handling callback
 *      @scmd:          sd-issued command that has failed
 *      @eh_disp:       The recovery disposition suggested by the midlayer
 *
 *      This function is called by the SCSI midlayer upon completion of an
 *      error test command (currently TEST UNIT READY). The result of sending
 *      the eh command is passed in eh_disp.  We're looking for devices that
 *      fail medium access commands but are OK with non access commands like
 *      test unit ready (so wrongly see the device as having a successful
 *      recovery)
 **/
static int sd_eh_action(struct scsi_cmnd *scmd, int eh_disp)
{
        struct scsi_disk *sdkp = scsi_disk(scsi_cmd_to_rq(scmd)->q->disk);
        struct scsi_device *sdev = scmd->device;

        if (!scsi_device_online(sdev) ||
            !scsi_medium_access_command(scmd) ||
            host_byte(scmd->result) != DID_TIME_OUT ||
            eh_disp != SUCCESS)
                return eh_disp;

        /*
         * The device has timed out executing a medium access command.
         * However, the TEST UNIT READY command sent during error
         * handling completed successfully. Either the device is in the
         * process of recovering or has it suffered an internal failure
         * that prevents access to the storage medium.
         */
        if (!sdkp->ignore_medium_access_errors) {
                sdkp->medium_access_timed_out++;
                sdkp->ignore_medium_access_errors = true;
        }

        /*
         * If the device keeps failing read/write commands but TEST UNIT
         * READY always completes successfully we assume that medium
         * access is no longer possible and take the device offline.
         */
        if (sdkp->medium_access_timed_out >= sdkp->max_medium_access_timeouts) {
                scmd_printk(KERN_ERR, scmd,
                            "Medium access timeout failure. Offlining disk!\n");
                mutex_lock(&sdev->state_mutex);
                scsi_device_set_state(sdev, SDEV_OFFLINE);
                mutex_unlock(&sdev->state_mutex);

                return SUCCESS;
        }

        return eh_disp;
}

static unsigned int sd_completed_bytes(struct scsi_cmnd *scmd)
{
        struct request *req = scsi_cmd_to_rq(scmd);
        struct scsi_device *sdev = scmd->device;
        unsigned int transferred, good_bytes;
        u64 start_lba, end_lba, bad_lba;

        /*
         * Some commands have a payload smaller than the device logical
         * block size (e.g. INQUIRY on a 4K disk).
         */
        if (scsi_bufflen(scmd) <= sdev->sector_size)
                return 0;

        /* Check if we have a 'bad_lba' information */
        if (!scsi_get_sense_info_fld(scmd->sense_buffer,
                                     SCSI_SENSE_BUFFERSIZE,
                                     &bad_lba))
                return 0;

        /*
         * If the bad lba was reported incorrectly, we have no idea where
         * the error is.
         */
        start_lba = sectors_to_logical(sdev, blk_rq_pos(req));
        end_lba = start_lba + bytes_to_logical(sdev, scsi_bufflen(scmd));
        if (bad_lba < start_lba || bad_lba >= end_lba)
                return 0;

        /*
         * resid is optional but mostly filled in.  When it's unused,
         * its value is zero, so we assume the whole buffer transferred
         */
        transferred = scsi_bufflen(scmd) - scsi_get_resid(scmd);

        /* This computation should always be done in terms of the
         * resolution of the device's medium.
         */
        good_bytes = logical_to_bytes(sdev, bad_lba - start_lba);

        return min(good_bytes, transferred);
}

/**
 *      sd_done - bottom half handler: called when the lower level
 *      driver has completed (successfully or otherwise) a scsi command.
 *      @SCpnt: mid-level's per command structure.
 *
 *      Note: potentially run from within an ISR. Must not block.
 **/
static int sd_done(struct scsi_cmnd *SCpnt)
{
        int result = SCpnt->result;
        unsigned int good_bytes = result ? 0 : scsi_bufflen(SCpnt);
        unsigned int sector_size = SCpnt->device->sector_size;
        unsigned int resid;
        struct scsi_sense_hdr sshdr;
        struct request *req = scsi_cmd_to_rq(SCpnt);
        struct scsi_disk *sdkp = scsi_disk(req->q->disk);
        int sense_valid = 0;
        int sense_deferred = 0;

        switch (req_op(req)) {
        case REQ_OP_DISCARD:
        case REQ_OP_WRITE_ZEROES:
        case REQ_OP_ZONE_RESET:
        case REQ_OP_ZONE_RESET_ALL:
        case REQ_OP_ZONE_OPEN:
        case REQ_OP_ZONE_CLOSE:
        case REQ_OP_ZONE_FINISH:
                if (!result) {
                        good_bytes = blk_rq_bytes(req);
                        scsi_set_resid(SCpnt, 0);
                } else {
                        good_bytes = 0;
                        scsi_set_resid(SCpnt, blk_rq_bytes(req));
                }
                break;
        default:
                /*
                 * In case of bogus fw or device, we could end up having
                 * an unaligned partial completion. Check this here and force
                 * alignment.
                 */
                resid = scsi_get_resid(SCpnt);
                if (resid & (sector_size - 1)) {
                        sd_printk(KERN_INFO, sdkp,
                                "Unaligned partial completion (resid=%u, sector_sz=%u)\n",
                                resid, sector_size);
                        scsi_print_command(SCpnt);
                        resid = min(scsi_bufflen(SCpnt),
                                    round_up(resid, sector_size));
                        scsi_set_resid(SCpnt, resid);
                }
        }

        if (result) {
                sense_valid = scsi_command_normalize_sense(SCpnt, &sshdr);
                if (sense_valid)
                        sense_deferred = scsi_sense_is_deferred(&sshdr);
        }
        sdkp->medium_access_timed_out = 0;

        if (!scsi_status_is_check_condition(result) &&
            (!sense_valid || sense_deferred))
                goto out;

        switch (sshdr.sense_key) {
        case HARDWARE_ERROR:
        case MEDIUM_ERROR:
                good_bytes = sd_completed_bytes(SCpnt);
                break;
        case RECOVERED_ERROR:
                good_bytes = scsi_bufflen(SCpnt);
                break;
        case NO_SENSE:
                /* This indicates a false check condition, so ignore it.  An
                 * unknown amount of data was transferred so treat it as an
                 * error.
                 */
                SCpnt->result = 0;
                memset(SCpnt->sense_buffer, 0, SCSI_SENSE_BUFFERSIZE);
                break;
        case ABORTED_COMMAND:
                if (sshdr.asc == 0x10)  /* DIF: Target detected corruption */
                        good_bytes = sd_completed_bytes(SCpnt);
                break;
        case ILLEGAL_REQUEST:
                switch (sshdr.asc) {
                case 0x10:      /* DIX: Host detected corruption */
                        good_bytes = sd_completed_bytes(SCpnt);
                        break;
                case 0x20:      /* INVALID COMMAND OPCODE */
                case 0x24:      /* INVALID FIELD IN CDB */
                        switch (SCpnt->cmnd[0]) {
                        case UNMAP:
                                sd_config_discard(sdkp, SD_LBP_DISABLE);
                                break;
                        case WRITE_SAME_16:
                        case WRITE_SAME:
                                if (SCpnt->cmnd[1] & 8) { /* UNMAP */
                                        sd_config_discard(sdkp, SD_LBP_DISABLE);
                                } else {
                                        sdkp->device->no_write_same = 1;
                                        sd_config_write_same(sdkp);
                                        req->rq_flags |= RQF_QUIET;
                                }
                                break;
                        }
                }
                break;
        default:
                break;
        }

 out:
        if (sd_is_zoned(sdkp))
                good_bytes = sd_zbc_complete(SCpnt, good_bytes, &sshdr);

        SCSI_LOG_HLCOMPLETE(1, scmd_printk(KERN_INFO, SCpnt,
                                           "sd_done: completed %d of %d bytes\n",
                                           good_bytes, scsi_bufflen(SCpnt)));

        return good_bytes;
}

/*
 * spinup disk - called only in sd_revalidate_disk()
 */
static void
sd_spinup_disk(struct scsi_disk *sdkp)
{
        unsigned char cmd[10];
        unsigned long spintime_expire = 0;
        int retries, spintime;
        unsigned int the_result;
        struct scsi_sense_hdr sshdr;
        const struct scsi_exec_args exec_args = {
                .sshdr = &sshdr,
        };
        int sense_valid = 0;

        spintime = 0;

        /* Spin up drives, as required.  Only do this at boot time */
        /* Spinup needs to be done for module loads too. */
        do {
                retries = 0;

                do {
                        bool media_was_present = sdkp->media_present;

                        cmd[0] = TEST_UNIT_READY;
                        memset((void *) &cmd[1], 0, 9);

                        the_result = scsi_execute_cmd(sdkp->device, cmd,
                                                      REQ_OP_DRV_IN, NULL, 0,
                                                      SD_TIMEOUT,
                                                      sdkp->max_retries,
                                                      &exec_args);

                        /*
                         * If the drive has indicated to us that it
                         * doesn't have any media in it, don't bother
                         * with any more polling.
                         */
                        if (media_not_present(sdkp, &sshdr)) {
                                if (media_was_present)
                                        sd_printk(KERN_NOTICE, sdkp, "Media removed, stopped polling\n");
                                return;
                        }

                        if (the_result)
                                sense_valid = scsi_sense_valid(&sshdr);
                        retries++;
                } while (retries < 3 &&
                         (!scsi_status_is_good(the_result) ||
                          (scsi_status_is_check_condition(the_result) &&
                          sense_valid && sshdr.sense_key == UNIT_ATTENTION)));

                if (!scsi_status_is_check_condition(the_result)) {
                        /* no sense, TUR either succeeded or failed
                         * with a status error */
                        if(!spintime && !scsi_status_is_good(the_result)) {
                                sd_print_result(sdkp, "Test Unit Ready failed",
                                                the_result);
                        }
                        break;
                }

                /*
                 * The device does not want the automatic start to be issued.
                 */
                if (sdkp->device->no_start_on_add)
                        break;

                if (sense_valid && sshdr.sense_key == NOT_READY) {
                        if (sshdr.asc == 4 && sshdr.ascq == 3)
                                break;  /* manual intervention required */
                        if (sshdr.asc == 4 && sshdr.ascq == 0xb)
                                break;  /* standby */
                        if (sshdr.asc == 4 && sshdr.ascq == 0xc)
                                break;  /* unavailable */
                        if (sshdr.asc == 4 && sshdr.ascq == 0x1b)
                                break;  /* sanitize in progress */
                        /*
                         * Issue command to spin up drive when not ready
                         */
                        if (!spintime) {
                                sd_printk(KERN_NOTICE, sdkp, "Spinning up disk...");
                                cmd[0] = START_STOP;
                                cmd[1] = 1;     /* Return immediately */
                                memset((void *) &cmd[2], 0, 8);
                                cmd[4] = 1;     /* Start spin cycle */
                                if (sdkp->device->start_stop_pwr_cond)
                                        cmd[4] |= 1 << 4;
                                scsi_execute_cmd(sdkp->device, cmd,
                                                 REQ_OP_DRV_IN, NULL, 0,
                                                 SD_TIMEOUT, sdkp->max_retries,
                                                 &exec_args);
                                spintime_expire = jiffies + 100 * HZ;
                                spintime = 1;
                        }
                        /* Wait 1 second for next try */
                        msleep(1000);
                        printk(KERN_CONT ".");

                /*
                 * Wait for USB flash devices with slow firmware.
                 * Yes, this sense key/ASC combination shouldn't
                 * occur here.  It's characteristic of these devices.
                 */
                } else if (sense_valid &&
                                sshdr.sense_key == UNIT_ATTENTION &&
                                sshdr.asc == 0x28) {
                        if (!spintime) {
                                spintime_expire = jiffies + 5 * HZ;
                                spintime = 1;
                        }
                        /* Wait 1 second for next try */
                        msleep(1000);
                } else {
                        /* we don't understand the sense code, so it's
                         * probably pointless to loop */
                        if(!spintime) {
                                sd_printk(KERN_NOTICE, sdkp, "Unit Not Ready\n");
                                sd_print_sense_hdr(sdkp, &sshdr);
                        }
                        break;
                }
                                
        } while (spintime && time_before_eq(jiffies, spintime_expire));

        if (spintime) {
                if (scsi_status_is_good(the_result))
                        printk(KERN_CONT "ready\n");
                else
                        printk(KERN_CONT "not responding...\n");
        }
}

/*
 * Determine whether disk supports Data Integrity Field.
 */
static int sd_read_protection_type(struct scsi_disk *sdkp, unsigned char *buffer)
{
        struct scsi_device *sdp = sdkp->device;
        u8 type;

        if (scsi_device_protection(sdp) == 0 || (buffer[12] & 1) == 0) {
                sdkp->protection_type = 0;
                return 0;
        }

        type = ((buffer[12] >> 1) & 7) + 1; /* P_TYPE 0 = Type 1 */

        if (type > T10_PI_TYPE3_PROTECTION) {
                sd_printk(KERN_ERR, sdkp, "formatted with unsupported"  \
                          " protection type %u. Disabling disk!\n",
                          type);
                sdkp->protection_type = 0;
                return -ENODEV;
        }

        sdkp->protection_type = type;

        return 0;
}

static void sd_config_protection(struct scsi_disk *sdkp)
{
        struct scsi_device *sdp = sdkp->device;

        sd_dif_config_host(sdkp);

        if (!sdkp->protection_type)
                return;

        if (!scsi_host_dif_capable(sdp->host, sdkp->protection_type)) {
                sd_first_printk(KERN_NOTICE, sdkp,
                                "Disabling DIF Type %u protection\n",
                                sdkp->protection_type);
                sdkp->protection_type = 0;
        }

        sd_first_printk(KERN_NOTICE, sdkp, "Enabling DIF Type %u protection\n",
                        sdkp->protection_type);
}

static void read_capacity_error(struct scsi_disk *sdkp, struct scsi_device *sdp,
                        struct scsi_sense_hdr *sshdr, int sense_valid,
                        int the_result)
{
        if (sense_valid)
                sd_print_sense_hdr(sdkp, sshdr);
        else
                sd_printk(KERN_NOTICE, sdkp, "Sense not available.\n");

        /*
         * Set dirty bit for removable devices if not ready -
         * sometimes drives will not report this properly.
         */
        if (sdp->removable &&
            sense_valid && sshdr->sense_key == NOT_READY)
                set_media_not_present(sdkp);

        /*
         * We used to set media_present to 0 here to indicate no media
         * in the drive, but some drives fail read capacity even with
         * media present, so we can't do that.
         */
        sdkp->capacity = 0; /* unknown mapped to zero - as usual */
}

#define RC16_LEN 32
#if RC16_LEN > SD_BUF_SIZE
#error RC16_LEN must not be more than SD_BUF_SIZE
#endif

#define READ_CAPACITY_RETRIES_ON_RESET  10

static int read_capacity_16(struct scsi_disk *sdkp, struct scsi_device *sdp,
                                                unsigned char *buffer)
{
        unsigned char cmd[16];
        struct scsi_sense_hdr sshdr;
        const struct scsi_exec_args exec_args = {
                .sshdr = &sshdr,
        };
        int sense_valid = 0;
        int the_result;
        int retries = 3, reset_retries = READ_CAPACITY_RETRIES_ON_RESET;
        unsigned int alignment;
        unsigned long long lba;
        unsigned sector_size;

        if (sdp->no_read_capacity_16)
                return -EINVAL;

        do {
                memset(cmd, 0, 16);
                cmd[0] = SERVICE_ACTION_IN_16;
                cmd[1] = SAI_READ_CAPACITY_16;
                cmd[13] = RC16_LEN;
                memset(buffer, 0, RC16_LEN);

                the_result = scsi_execute_cmd(sdp, cmd, REQ_OP_DRV_IN,
                                              buffer, RC16_LEN, SD_TIMEOUT,
                                              sdkp->max_retries, &exec_args);

                if (media_not_present(sdkp, &sshdr))
                        return -ENODEV;

                if (the_result > 0) {
                        sense_valid = scsi_sense_valid(&sshdr);
                        if (sense_valid &&
                            sshdr.sense_key == ILLEGAL_REQUEST &&
                            (sshdr.asc == 0x20 || sshdr.asc == 0x24) &&
                            sshdr.ascq == 0x00)
                                /* Invalid Command Operation Code or
                                 * Invalid Field in CDB, just retry
                                 * silently with RC10 */
                                return -EINVAL;
                        if (sense_valid &&
                            sshdr.sense_key == UNIT_ATTENTION &&
                            sshdr.asc == 0x29 && sshdr.ascq == 0x00)
                                /* Device reset might occur several times,
                                 * give it one more chance */
                                if (--reset_retries > 0)
                                        continue;
                }
                retries--;

        } while (the_result && retries);

        if (the_result) {
                sd_print_result(sdkp, "Read Capacity(16) failed", the_result);
                read_capacity_error(sdkp, sdp, &sshdr, sense_valid, the_result);
                return -EINVAL;
        }

        sector_size = get_unaligned_be32(&buffer[8]);
        lba = get_unaligned_be64(&buffer[0]);

        if (sd_read_protection_type(sdkp, buffer) < 0) {
                sdkp->capacity = 0;
                return -ENODEV;
        }

        /* Logical blocks per physical block exponent */
        sdkp->physical_block_size = (1 << (buffer[13] & 0xf)) * sector_size;

        /* RC basis */
        sdkp->rc_basis = (buffer[12] >> 4) & 0x3;

        /* Lowest aligned logical block */
        alignment = ((buffer[14] & 0x3f) << 8 | buffer[15]) * sector_size;
        blk_queue_alignment_offset(sdp->request_queue, alignment);
        if (alignment && sdkp->first_scan)
                sd_printk(KERN_NOTICE, sdkp,
                          "physical block alignment offset: %u\n", alignment);

        if (buffer[14] & 0x80) { /* LBPME */
                sdkp->lbpme = 1;

                if (buffer[14] & 0x40) /* LBPRZ */
                        sdkp->lbprz = 1;

                sd_config_discard(sdkp, SD_LBP_WS16);
        }

        sdkp->capacity = lba + 1;
        return sector_size;
}

static int read_capacity_10(struct scsi_disk *sdkp, struct scsi_device *sdp,
                                                unsigned char *buffer)
{
        unsigned char cmd[16];
        struct scsi_sense_hdr sshdr;
        const struct scsi_exec_args exec_args = {
                .sshdr = &sshdr,
        };
        int sense_valid = 0;
        int the_result;
        int retries = 3, reset_retries = READ_CAPACITY_RETRIES_ON_RESET;
        sector_t lba;
        unsigned sector_size;

        do {
                cmd[0] = READ_CAPACITY;
                memset(&cmd[1], 0, 9);
                memset(buffer, 0, 8);

                the_result = scsi_execute_cmd(sdp, cmd, REQ_OP_DRV_IN, buffer,
                                              8, SD_TIMEOUT, sdkp->max_retries,
                                              &exec_args);

                if (media_not_present(sdkp, &sshdr))
                        return -ENODEV;

                if (the_result > 0) {
                        sense_valid = scsi_sense_valid(&sshdr);
                        if (sense_valid &&
                            sshdr.sense_key == UNIT_ATTENTION &&
                            sshdr.asc == 0x29 && sshdr.ascq == 0x00)
                                /* Device reset might occur several times,
                                 * give it one more chance */
                                if (--reset_retries > 0)
                                        continue;
                }
                retries--;

        } while (the_result && retries);

        if (the_result) {
                sd_print_result(sdkp, "Read Capacity(10) failed", the_result);
                read_capacity_error(sdkp, sdp, &sshdr, sense_valid, the_result);
                return -EINVAL;
        }

        sector_size = get_unaligned_be32(&buffer[4]);
        lba = get_unaligned_be32(&buffer[0]);

        if (sdp->no_read_capacity_16 && (lba == 0xffffffff)) {
                /* Some buggy (usb cardreader) devices return an lba of
                   0xffffffff when the want to report a size of 0 (with
                   which they really mean no media is present) */
                sdkp->capacity = 0;
                sdkp->physical_block_size = sector_size;
                return sector_size;
        }

        sdkp->capacity = lba + 1;
        sdkp->physical_block_size = sector_size;
        return sector_size;
}

static int sd_try_rc16_first(struct scsi_device *sdp)
{
        if (sdp->host->max_cmd_len < 16)
                return 0;
        if (sdp->try_rc_10_first)
                return 0;
        if (sdp->scsi_level > SCSI_SPC_2)
                return 1;
        if (scsi_device_protection(sdp))
                return 1;
        return 0;
}

/*
 * read disk capacity
 */
static void
sd_read_capacity(struct scsi_disk *sdkp, unsigned char *buffer)
{
        int sector_size;
        struct scsi_device *sdp = sdkp->device;

        if (sd_try_rc16_first(sdp)) {
                sector_size = read_capacity_16(sdkp, sdp, buffer);
                if (sector_size == -EOVERFLOW)
                        goto got_data;
                if (sector_size == -ENODEV)
                        return;
                if (sector_size < 0)
                        sector_size = read_capacity_10(sdkp, sdp, buffer);
                if (sector_size < 0)
                        return;
        } else {
                sector_size = read_capacity_10(sdkp, sdp, buffer);
                if (sector_size == -EOVERFLOW)
                        goto got_data;
                if (sector_size < 0)
                        return;
                if ((sizeof(sdkp->capacity) > 4) &&
                    (sdkp->capacity > 0xffffffffULL)) {
                        int old_sector_size = sector_size;
                        sd_printk(KERN_NOTICE, sdkp, "Very big device. "
                                        "Trying to use READ CAPACITY(16).\n");
                        sector_size = read_capacity_16(sdkp, sdp, buffer);
                        if (sector_size < 0) {
                                sd_printk(KERN_NOTICE, sdkp,
                                        "Using 0xffffffff as device size\n");
                                sdkp->capacity = 1 + (sector_t) 0xffffffff;
                                sector_size = old_sector_size;
                                goto got_data;
                        }
                        /* Remember that READ CAPACITY(16) succeeded */
                        sdp->try_rc_10_first = 0;
                }
        }

        /* Some devices are known to return the total number of blocks,
         * not the highest block number.  Some devices have versions
         * which do this and others which do not.  Some devices we might
         * suspect of doing this but we don't know for certain.
         *
         * If we know the reported capacity is wrong, decrement it.  If
         * we can only guess, then assume the number of blocks is even
         * (usually true but not always) and err on the side of lowering
         * the capacity.
         */
        if (sdp->fix_capacity ||
            (sdp->guess_capacity && (sdkp->capacity & 0x01))) {
                sd_printk(KERN_INFO, sdkp, "Adjusting the sector count "
                                "from its reported value: %llu\n",
                                (unsigned long long) sdkp->capacity);
                --sdkp->capacity;
        }

got_data:
        if (sector_size == 0) {
                sector_size = 512;
                sd_printk(KERN_NOTICE, sdkp, "Sector size 0 reported, "
                          "assuming 512.\n");
        }

        if (sector_size != 512 &&
            sector_size != 1024 &&
            sector_size != 2048 &&
            sector_size != 4096) {
                sd_printk(KERN_NOTICE, sdkp, "Unsupported sector size %d.\n",
                          sector_size);
                /*
                 * The user might want to re-format the drive with
                 * a supported sectorsize.  Once this happens, it
                 * would be relatively trivial to set the thing up.
                 * For this reason, we leave the thing in the table.
                 */
                sdkp->capacity = 0;
                /*
                 * set a bogus sector size so the normal read/write
                 * logic in the block layer will eventually refuse any
                 * request on this device without tripping over power
                 * of two sector size assumptions
                 */
                sector_size = 512;
        }
        blk_queue_logical_block_size(sdp->request_queue, sector_size);
        blk_queue_physical_block_size(sdp->request_queue,
                                      sdkp->physical_block_size);
        sdkp->device->sector_size = sector_size;

        if (sdkp->capacity > 0xffffffff)
                sdp->use_16_for_rw = 1;

}

/*
 * Print disk capacity
 */
static void
sd_print_capacity(struct scsi_disk *sdkp,
                  sector_t old_capacity)
{
        int sector_size = sdkp->device->sector_size;
        char cap_str_2[10], cap_str_10[10];

        if (!sdkp->first_scan && old_capacity == sdkp->capacity)
                return;

        string_get_size(sdkp->capacity, sector_size,
                        STRING_UNITS_2, cap_str_2, sizeof(cap_str_2));
        string_get_size(sdkp->capacity, sector_size,
                        STRING_UNITS_10, cap_str_10, sizeof(cap_str_10));

        sd_printk(KERN_NOTICE, sdkp,
                  "%llu %d-byte logical blocks: (%s/%s)\n",
                  (unsigned long long)sdkp->capacity,
                  sector_size, cap_str_10, cap_str_2);

        if (sdkp->physical_block_size != sector_size)
                sd_printk(KERN_NOTICE, sdkp,
                          "%u-byte physical blocks\n",
                          sdkp->physical_block_size);
}

/* called with buffer of length 512 */
static inline int
sd_do_mode_sense(struct scsi_disk *sdkp, int dbd, int modepage,
                 unsigned char *buffer, int len, struct scsi_mode_data *data,
                 struct scsi_sense_hdr *sshdr)
{
        /*
         * If we must use MODE SENSE(10), make sure that the buffer length
         * is at least 8 bytes so that the mode sense header fits.
         */
        if (sdkp->device->use_10_for_ms && len < 8)
                len = 8;

        return scsi_mode_sense(sdkp->device, dbd, modepage, 0, buffer, len,
                               SD_TIMEOUT, sdkp->max_retries, data, sshdr);
}

/*
 * read write protect setting, if possible - called only in sd_revalidate_disk()
 * called with buffer of length SD_BUF_SIZE
 */
static void
sd_read_write_protect_flag(struct scsi_disk *sdkp, unsigned char *buffer)
{
        int res;
        struct scsi_device *sdp = sdkp->device;
        struct scsi_mode_data data;
        int old_wp = sdkp->write_prot;

        set_disk_ro(sdkp->disk, 0);
        if (sdp->skip_ms_page_3f) {
                sd_first_printk(KERN_NOTICE, sdkp, "Assuming Write Enabled\n");
                return;
        }

        if (sdp->use_192_bytes_for_3f) {
                res = sd_do_mode_sense(sdkp, 0, 0x3F, buffer, 192, &data, NULL);
        } else {
                /*
                 * First attempt: ask for all pages (0x3F), but only 4 bytes.
                 * We have to start carefully: some devices hang if we ask
                 * for more than is available.
                 */
                res = sd_do_mode_sense(sdkp, 0, 0x3F, buffer, 4, &data, NULL);

                /*
                 * Second attempt: ask for page 0 When only page 0 is
                 * implemented, a request for page 3F may return Sense Key
                 * 5: Illegal Request, Sense Code 24: Invalid field in
                 * CDB.
                 */
                if (res < 0)
                        res = sd_do_mode_sense(sdkp, 0, 0, buffer, 4, &data, NULL);

                /*
                 * Third attempt: ask 255 bytes, as we did earlier.
                 */
                if (res < 0)
                        res = sd_do_mode_sense(sdkp, 0, 0x3F, buffer, 255,
                                               &data, NULL);
        }

        if (res < 0) {
                sd_first_printk(KERN_WARNING, sdkp,
                          "Test WP failed, assume Write Enabled\n");
        } else {
                sdkp->write_prot = ((data.device_specific & 0x80) != 0);
                set_disk_ro(sdkp->disk, sdkp->write_prot);
                if (sdkp->first_scan || old_wp != sdkp->write_prot) {
                        sd_printk(KERN_NOTICE, sdkp, "Write Protect is %s\n",
                                  sdkp->write_prot ? "on" : "off");
                        sd_printk(KERN_DEBUG, sdkp, "Mode Sense: %4ph\n", buffer);
                }
        }
}

/*
 * sd_read_cache_type - called only from sd_revalidate_disk()
 * called with buffer of length SD_BUF_SIZE
 */
static void
sd_read_cache_type(struct scsi_disk *sdkp, unsigned char *buffer)
{
        int len = 0, res;
        struct scsi_device *sdp = sdkp->device;

        int dbd;
        int modepage;
        int first_len;
        struct scsi_mode_data data;
        struct scsi_sense_hdr sshdr;
        int old_wce = sdkp->WCE;
        int old_rcd = sdkp->RCD;
        int old_dpofua = sdkp->DPOFUA;


        if (sdkp->cache_override)
                return;

        first_len = 4;
        if (sdp->skip_ms_page_8) {
                if (sdp->type == TYPE_RBC)
                        goto defaults;
                else {
                        if (sdp->skip_ms_page_3f)
                                goto defaults;
                        modepage = 0x3F;
                        if (sdp->use_192_bytes_for_3f)
                                first_len = 192;
                        dbd = 0;
                }
        } else if (sdp->type == TYPE_RBC) {
                modepage = 6;
                dbd = 8;
        } else {
                modepage = 8;
                dbd = 0;
        }

        /* cautiously ask */
        res = sd_do_mode_sense(sdkp, dbd, modepage, buffer, first_len,
                        &data, &sshdr);

        if (res < 0)
                goto bad_sense;

        if (!data.header_length) {
                modepage = 6;
                first_len = 0;
                sd_first_printk(KERN_ERR, sdkp,
                                "Missing header in MODE_SENSE response\n");
        }

        /* that went OK, now ask for the proper length */
        len = data.length;

        /*
         * We're only interested in the first three bytes, actually.
         * But the data cache page is defined for the first 20.
         */
        if (len < 3)
                goto bad_sense;
        else if (len > SD_BUF_SIZE) {
                sd_first_printk(KERN_NOTICE, sdkp, "Truncating mode parameter "
                          "data from %d to %d bytes\n", len, SD_BUF_SIZE);
                len = SD_BUF_SIZE;
        }
        if (modepage == 0x3F && sdp->use_192_bytes_for_3f)
                len = 192;

        /* Get the data */
        if (len > first_len)
                res = sd_do_mode_sense(sdkp, dbd, modepage, buffer, len,
                                &data, &sshdr);

        if (!res) {
                int offset = data.header_length + data.block_descriptor_length;

                while (offset < len) {
                        u8 page_code = buffer[offset] & 0x3F;
                        u8 spf       = buffer[offset] & 0x40;

                        if (page_code == 8 || page_code == 6) {
                                /* We're interested only in the first 3 bytes.
                                 */
                                if (len - offset <= 2) {
                                        sd_first_printk(KERN_ERR, sdkp,
                                                "Incomplete mode parameter "
                                                        "data\n");
                                        goto defaults;
                                } else {
                                        modepage = page_code;
                                        goto Page_found;
                                }
                        } else {
                                /* Go to the next page */
                                if (spf && len - offset > 3)
                                        offset += 4 + (buffer[offset+2] << 8) +
                                                buffer[offset+3];
                                else if (!spf && len - offset > 1)
                                        offset += 2 + buffer[offset+1];
                                else {
                                        sd_first_printk(KERN_ERR, sdkp,
                                                        "Incomplete mode "
                                                        "parameter data\n");
                                        goto defaults;
                                }
                        }
                }

                sd_first_printk(KERN_WARNING, sdkp,
                                "No Caching mode page found\n");
                goto defaults;

        Page_found:
                if (modepage == 8) {
                        sdkp->WCE = ((buffer[offset + 2] & 0x04) != 0);
                        sdkp->RCD = ((buffer[offset + 2] & 0x01) != 0);
                } else {
                        sdkp->WCE = ((buffer[offset + 2] & 0x01) == 0);
                        sdkp->RCD = 0;
                }

                sdkp->DPOFUA = (data.device_specific & 0x10) != 0;
                if (sdp->broken_fua) {
                        sd_first_printk(KERN_NOTICE, sdkp, "Disabling FUA\n");
                        sdkp->DPOFUA = 0;
                } else if (sdkp->DPOFUA && !sdkp->device->use_10_for_rw &&
                           !sdkp->device->use_16_for_rw) {
                        sd_first_printk(KERN_NOTICE, sdkp,
                                  "Uses READ/WRITE(6), disabling FUA\n");
                        sdkp->DPOFUA = 0;
                }

                /* No cache flush allowed for write protected devices */
                if (sdkp->WCE && sdkp->write_prot)
                        sdkp->WCE = 0;

                if (sdkp->first_scan || old_wce != sdkp->WCE ||
                    old_rcd != sdkp->RCD || old_dpofua != sdkp->DPOFUA)
                        sd_printk(KERN_NOTICE, sdkp,
                                  "Write cache: %s, read cache: %s, %s\n",
                                  sdkp->WCE ? "enabled" : "disabled",
                                  sdkp->RCD ? "disabled" : "enabled",
                                  sdkp->DPOFUA ? "supports DPO and FUA"
                                  : "doesn't support DPO or FUA");

                return;
        }

bad_sense:
        if (scsi_sense_valid(&sshdr) &&
            sshdr.sense_key == ILLEGAL_REQUEST &&
            sshdr.asc == 0x24 && sshdr.ascq == 0x0)
                /* Invalid field in CDB */
                sd_first_printk(KERN_NOTICE, sdkp, "Cache data unavailable\n");
        else
                sd_first_printk(KERN_ERR, sdkp,
                                "Asking for cache data failed\n");

defaults:
        if (sdp->wce_default_on) {
                sd_first_printk(KERN_NOTICE, sdkp,
                                "Assuming drive cache: write back\n");
                sdkp->WCE = 1;
        } else {
                sd_first_printk(KERN_WARNING, sdkp,
                                "Assuming drive cache: write through\n");
                sdkp->WCE = 0;
        }
        sdkp->RCD = 0;
        sdkp->DPOFUA = 0;
}

/*
 * The ATO bit indicates whether the DIF application tag is available
 * for use by the operating system.
 */
static void sd_read_app_tag_own(struct scsi_disk *sdkp, unsigned char *buffer)
{
        int res, offset;
        struct scsi_device *sdp = sdkp->device;
        struct scsi_mode_data data;
        struct scsi_sense_hdr sshdr;

        if (sdp->type != TYPE_DISK && sdp->type != TYPE_ZBC)
                return;

        if (sdkp->protection_type == 0)
                return;

        res = scsi_mode_sense(sdp, 1, 0x0a, 0, buffer, 36, SD_TIMEOUT,
                              sdkp->max_retries, &data, &sshdr);

        if (res < 0 || !data.header_length ||
            data.length < 6) {
                sd_first_printk(KERN_WARNING, sdkp,
                          "getting Control mode page failed, assume no ATO\n");

                if (scsi_sense_valid(&sshdr))
                        sd_print_sense_hdr(sdkp, &sshdr);

                return;
        }

        offset = data.header_length + data.block_descriptor_length;

        if ((buffer[offset] & 0x3f) != 0x0a) {
                sd_first_printk(KERN_ERR, sdkp, "ATO Got wrong page\n");
                return;
        }

        if ((buffer[offset + 5] & 0x80) == 0)
                return;

        sdkp->ATO = 1;

        return;
}

/**
 * sd_read_block_limits - Query disk device for preferred I/O sizes.
 * @sdkp: disk to query
 */
static void sd_read_block_limits(struct scsi_disk *sdkp)
{
        struct scsi_vpd *vpd;

        rcu_read_lock();

        vpd = rcu_dereference(sdkp->device->vpd_pgb0);
        if (!vpd || vpd->len < 16)
                goto out;

        sdkp->min_xfer_blocks = get_unaligned_be16(&vpd->data[6]);
        sdkp->max_xfer_blocks = get_unaligned_be32(&vpd->data[8]);
        sdkp->opt_xfer_blocks = get_unaligned_be32(&vpd->data[12]);

        if (vpd->len >= 64) {
                unsigned int lba_count, desc_count;

                sdkp->max_ws_blocks = (u32)get_unaligned_be64(&vpd->data[36]);

                if (!sdkp->lbpme)
                        goto out;

                lba_count = get_unaligned_be32(&vpd->data[20]);
                desc_count = get_unaligned_be32(&vpd->data[24]);

                if (lba_count && desc_count)
                        sdkp->max_unmap_blocks = lba_count;

                sdkp->unmap_granularity = get_unaligned_be32(&vpd->data[28]);

                if (vpd->data[32] & 0x80)
                        sdkp->unmap_alignment =
                                get_unaligned_be32(&vpd->data[32]) & ~(1 << 31);

                if (!sdkp->lbpvpd) { /* LBP VPD page not provided */

                        if (sdkp->max_unmap_blocks)
                                sd_config_discard(sdkp, SD_LBP_UNMAP);
                        else
                                sd_config_discard(sdkp, SD_LBP_WS16);

                } else {        /* LBP VPD page tells us what to use */
                        if (sdkp->lbpu && sdkp->max_unmap_blocks)
                                sd_config_discard(sdkp, SD_LBP_UNMAP);
                        else if (sdkp->lbpws)
                                sd_config_discard(sdkp, SD_LBP_WS16);
                        else if (sdkp->lbpws10)
                                sd_config_discard(sdkp, SD_LBP_WS10);
                        else
                                sd_config_discard(sdkp, SD_LBP_DISABLE);
                }
        }

 out:
        rcu_read_unlock();
}

/**
 * sd_read_block_characteristics - Query block dev. characteristics
 * @sdkp: disk to query
 */
static void sd_read_block_characteristics(struct scsi_disk *sdkp)
{
        struct request_queue *q = sdkp->disk->queue;
        struct scsi_vpd *vpd;
        u16 rot;
        u8 zoned;

        rcu_read_lock();
        vpd = rcu_dereference(sdkp->device->vpd_pgb1);

        if (!vpd || vpd->len < 8) {
                rcu_read_unlock();
                return;
        }

        rot = get_unaligned_be16(&vpd->data[4]);
        zoned = (vpd->data[8] >> 4) & 3;
        rcu_read_unlock();

        if (rot == 1) {
                blk_queue_flag_set(QUEUE_FLAG_NONROT, q);
                blk_queue_flag_clear(QUEUE_FLAG_ADD_RANDOM, q);
        }

        if (sdkp->device->type == TYPE_ZBC) {
                /*
                 * Host-managed: Per ZBC and ZAC specifications, writes in
                 * sequential write required zones of host-managed devices must
                 * be aligned to the device physical block size.
                 */
                disk_set_zoned(sdkp->disk, BLK_ZONED_HM);
                blk_queue_zone_write_granularity(q, sdkp->physical_block_size);
        } else {
                sdkp->zoned = zoned;
                if (sdkp->zoned == 1) {
                        /* Host-aware */
                        disk_set_zoned(sdkp->disk, BLK_ZONED_HA);
                } else {
                        /* Regular disk or drive managed disk */
                        disk_set_zoned(sdkp->disk, BLK_ZONED_NONE);
                }
        }

        if (!sdkp->first_scan)
                return;

        if (blk_queue_is_zoned(q)) {
                sd_printk(KERN_NOTICE, sdkp, "Host-%s zoned block device\n",
                      q->limits.zoned == BLK_ZONED_HM ? "managed" : "aware");
        } else {
                if (sdkp->zoned == 1)
                        sd_printk(KERN_NOTICE, sdkp,
                                  "Host-aware SMR disk used as regular disk\n");
                else if (sdkp->zoned == 2)
                        sd_printk(KERN_NOTICE, sdkp,
                                  "Drive-managed SMR disk\n");
        }
}

/**
 * sd_read_block_provisioning - Query provisioning VPD page
 * @sdkp: disk to query
 */
static void sd_read_block_provisioning(struct scsi_disk *sdkp)
{
        struct scsi_vpd *vpd;

        if (sdkp->lbpme == 0)
                return;

        rcu_read_lock();
        vpd = rcu_dereference(sdkp->device->vpd_pgb2);

        if (!vpd || vpd->len < 8) {
                rcu_read_unlock();
                return;
        }

        sdkp->lbpvpd    = 1;
        sdkp->lbpu      = (vpd->data[5] >> 7) & 1; /* UNMAP */
        sdkp->lbpws     = (vpd->data[5] >> 6) & 1; /* WRITE SAME(16) w/ UNMAP */
        sdkp->lbpws10   = (vpd->data[5] >> 5) & 1; /* WRITE SAME(10) w/ UNMAP */
        rcu_read_unlock();
}

static void sd_read_write_same(struct scsi_disk *sdkp, unsigned char *buffer)
{
        struct scsi_device *sdev = sdkp->device;

        if (sdev->host->no_write_same) {
                sdev->no_write_same = 1;

                return;
        }

        if (scsi_report_opcode(sdev, buffer, SD_BUF_SIZE, INQUIRY, 0) < 0) {
                struct scsi_vpd *vpd;

                sdev->no_report_opcodes = 1;

                /* Disable WRITE SAME if REPORT SUPPORTED OPERATION
                 * CODES is unsupported and the device has an ATA
                 * Information VPD page (SAT).
                 */
                rcu_read_lock();
                vpd = rcu_dereference(sdev->vpd_pg89);
                if (vpd)
                        sdev->no_write_same = 1;
                rcu_read_unlock();
        }

        if (scsi_report_opcode(sdev, buffer, SD_BUF_SIZE, WRITE_SAME_16, 0) == 1)
                sdkp->ws16 = 1;

        if (scsi_report_opcode(sdev, buffer, SD_BUF_SIZE, WRITE_SAME, 0) == 1)
                sdkp->ws10 = 1;
}

static void sd_read_security(struct scsi_disk *sdkp, unsigned char *buffer)
{
        struct scsi_device *sdev = sdkp->device;

        if (!sdev->security_supported)
                return;

        if (scsi_report_opcode(sdev, buffer, SD_BUF_SIZE,
                        SECURITY_PROTOCOL_IN, 0) == 1 &&
            scsi_report_opcode(sdev, buffer, SD_BUF_SIZE,
                        SECURITY_PROTOCOL_OUT, 0) == 1)
                sdkp->security = 1;
}

static inline sector_t sd64_to_sectors(struct scsi_disk *sdkp, u8 *buf)
{
        return logical_to_sectors(sdkp->device, get_unaligned_be64(buf));
}

/**
 * sd_read_cpr - Query concurrent positioning ranges
 * @sdkp:       disk to query
 */
static void sd_read_cpr(struct scsi_disk *sdkp)
{
        struct blk_independent_access_ranges *iars = NULL;
        unsigned char *buffer = NULL;
        unsigned int nr_cpr = 0;
        int i, vpd_len, buf_len = SD_BUF_SIZE;
        u8 *desc;

        /*
         * We need to have the capacity set first for the block layer to be
         * able to check the ranges.
         */
        if (sdkp->first_scan)
                return;

        if (!sdkp->capacity)
                goto out;

        /*
         * Concurrent Positioning Ranges VPD: there can be at most 256 ranges,
         * leading to a maximum page size of 64 + 256*32 bytes.
         */
        buf_len = 64 + 256*32;
        buffer = kmalloc(buf_len, GFP_KERNEL);
        if (!buffer || scsi_get_vpd_page(sdkp->device, 0xb9, buffer, buf_len))
                goto out;

        /* We must have at least a 64B header and one 32B range descriptor */
        vpd_len = get_unaligned_be16(&buffer[2]) + 4;
        if (vpd_len > buf_len || vpd_len < 64 + 32 || (vpd_len & 31)) {
                sd_printk(KERN_ERR, sdkp,
                          "Invalid Concurrent Positioning Ranges VPD page\n");
                goto out;
        }

        nr_cpr = (vpd_len - 64) / 32;
        if (nr_cpr == 1) {
                nr_cpr = 0;
                goto out;
        }

        iars = disk_alloc_independent_access_ranges(sdkp->disk, nr_cpr);
        if (!iars) {
                nr_cpr = 0;
                goto out;
        }

        desc = &buffer[64];
        for (i = 0; i < nr_cpr; i++, desc += 32) {
                if (desc[0] != i) {
                        sd_printk(KERN_ERR, sdkp,
                                "Invalid Concurrent Positioning Range number\n");
                        nr_cpr = 0;
                        break;
                }

                iars->ia_range[i].sector = sd64_to_sectors(sdkp, desc + 8);
                iars->ia_range[i].nr_sectors = sd64_to_sectors(sdkp, desc + 16);
        }

out:
        disk_set_independent_access_ranges(sdkp->disk, iars);
        if (nr_cpr && sdkp->nr_actuators != nr_cpr) {
                sd_printk(KERN_NOTICE, sdkp,
                          "%u concurrent positioning ranges\n", nr_cpr);
                sdkp->nr_actuators = nr_cpr;
        }

        kfree(buffer);
}

static bool sd_validate_min_xfer_size(struct scsi_disk *sdkp)
{
        struct scsi_device *sdp = sdkp->device;
        unsigned int min_xfer_bytes =
                logical_to_bytes(sdp, sdkp->min_xfer_blocks);

        if (sdkp->min_xfer_blocks == 0)
                return false;

        if (min_xfer_bytes & (sdkp->physical_block_size - 1)) {
                sd_first_printk(KERN_WARNING, sdkp,
                                "Preferred minimum I/O size %u bytes not a " \
                                "multiple of physical block size (%u bytes)\n",
                                min_xfer_bytes, sdkp->physical_block_size);
                sdkp->min_xfer_blocks = 0;
                return false;
        }

        sd_first_printk(KERN_INFO, sdkp, "Preferred minimum I/O size %u bytes\n",
                        min_xfer_bytes);
        return true;
}

/*
 * Determine the device's preferred I/O size for reads and writes
 * unless the reported value is unreasonably small, large, not a
 * multiple of the physical block size, or simply garbage.
 */
static bool sd_validate_opt_xfer_size(struct scsi_disk *sdkp,
                                      unsigned int dev_max)
{
        struct scsi_device *sdp = sdkp->device;
        unsigned int opt_xfer_bytes =
                logical_to_bytes(sdp, sdkp->opt_xfer_blocks);
        unsigned int min_xfer_bytes =
                logical_to_bytes(sdp, sdkp->min_xfer_blocks);

        if (sdkp->opt_xfer_blocks == 0)
                return false;

        if (sdkp->opt_xfer_blocks > dev_max) {
                sd_first_printk(KERN_WARNING, sdkp,
                                "Optimal transfer size %u logical blocks " \
                                "> dev_max (%u logical blocks)\n",
                                sdkp->opt_xfer_blocks, dev_max);
                return false;
        }

        if (sdkp->opt_xfer_blocks > SD_DEF_XFER_BLOCKS) {
                sd_first_printk(KERN_WARNING, sdkp,
                                "Optimal transfer size %u logical blocks " \
                                "> sd driver limit (%u logical blocks)\n",
                                sdkp->opt_xfer_blocks, SD_DEF_XFER_BLOCKS);
                return false;
        }

        if (opt_xfer_bytes < PAGE_SIZE) {
                sd_first_printk(KERN_WARNING, sdkp,
                                "Optimal transfer size %u bytes < " \
                                "PAGE_SIZE (%u bytes)\n",
                                opt_xfer_bytes, (unsigned int)PAGE_SIZE);
                return false;
        }

        if (min_xfer_bytes && opt_xfer_bytes % min_xfer_bytes) {
                sd_first_printk(KERN_WARNING, sdkp,
                                "Optimal transfer size %u bytes not a " \
                                "multiple of preferred minimum block " \
                                "size (%u bytes)\n",
                                opt_xfer_bytes, min_xfer_bytes);
                return false;
        }

        if (opt_xfer_bytes & (sdkp->physical_block_size - 1)) {
                sd_first_printk(KERN_WARNING, sdkp,
                                "Optimal transfer size %u bytes not a " \
                                "multiple of physical block size (%u bytes)\n",
                                opt_xfer_bytes, sdkp->physical_block_size);
                return false;
        }

        sd_first_printk(KERN_INFO, sdkp, "Optimal transfer size %u bytes\n",
                        opt_xfer_bytes);
        return true;
}

/**
 *      sd_revalidate_disk - called the first time a new disk is seen,
 *      performs disk spin up, read_capacity, etc.
 *      @disk: struct gendisk we care about
 **/
static int sd_revalidate_disk(struct gendisk *disk)
{
        struct scsi_disk *sdkp = scsi_disk(disk);
        struct scsi_device *sdp = sdkp->device;
        struct request_queue *q = sdkp->disk->queue;
        sector_t old_capacity = sdkp->capacity;
        unsigned char *buffer;
        unsigned int dev_max, rw_max;

        SCSI_LOG_HLQUEUE(3, sd_printk(KERN_INFO, sdkp,
                                      "sd_revalidate_disk\n"));

        /*
         * If the device is offline, don't try and read capacity or any
         * of the other niceties.
         */
        if (!scsi_device_online(sdp))
                goto out;

        buffer = kmalloc(SD_BUF_SIZE, GFP_KERNEL);
        if (!buffer) {
                sd_printk(KERN_WARNING, sdkp, "sd_revalidate_disk: Memory "
                          "allocation failure.\n");
                goto out;
        }

        sd_spinup_disk(sdkp);

        /*
         * Without media there is no reason to ask; moreover, some devices
         * react badly if we do.
         */
        if (sdkp->media_present) {
                sd_read_capacity(sdkp, buffer);

                /*
                 * set the default to rotational.  All non-rotational devices
                 * support the block characteristics VPD page, which will
                 * cause this to be updated correctly and any device which
                 * doesn't support it should be treated as rotational.
                 */
                blk_queue_flag_clear(QUEUE_FLAG_NONROT, q);
                blk_queue_flag_set(QUEUE_FLAG_ADD_RANDOM, q);

                if (scsi_device_supports_vpd(sdp)) {
                        sd_read_block_provisioning(sdkp);
                        sd_read_block_limits(sdkp);
                        sd_read_block_characteristics(sdkp);
                        sd_zbc_read_zones(sdkp, buffer);
                        sd_read_cpr(sdkp);
                }

                sd_print_capacity(sdkp, old_capacity);

                sd_read_write_protect_flag(sdkp, buffer);
                sd_read_cache_type(sdkp, buffer);
                sd_read_app_tag_own(sdkp, buffer);
                sd_read_write_same(sdkp, buffer);
                sd_read_security(sdkp, buffer);
                sd_config_protection(sdkp);
        }

        /*
         * We now have all cache related info, determine how we deal
         * with flush requests.
         */
        sd_set_flush_flag(sdkp);

        /* Initial block count limit based on CDB TRANSFER LENGTH field size. */
        dev_max = sdp->use_16_for_rw ? SD_MAX_XFER_BLOCKS : SD_DEF_XFER_BLOCKS;

        /* Some devices report a maximum block count for READ/WRITE requests. */
        dev_max = min_not_zero(dev_max, sdkp->max_xfer_blocks);
        q->limits.max_dev_sectors = logical_to_sectors(sdp, dev_max);

        if (sd_validate_min_xfer_size(sdkp))
                blk_queue_io_min(sdkp->disk->queue,
                                 logical_to_bytes(sdp, sdkp->min_xfer_blocks));
        else
                blk_queue_io_min(sdkp->disk->queue, 0);

        if (sd_validate_opt_xfer_size(sdkp, dev_max)) {
                q->limits.io_opt = logical_to_bytes(sdp, sdkp->opt_xfer_blocks);
                rw_max = logical_to_sectors(sdp, sdkp->opt_xfer_blocks);
        } else {
                q->limits.io_opt = 0;
                rw_max = min_not_zero(logical_to_sectors(sdp, dev_max),
                                      (sector_t)BLK_DEF_MAX_SECTORS);
        }

        /*
         * Limit default to SCSI host optimal sector limit if set. There may be
         * an impact on performance for when the size of a request exceeds this
         * host limit.
         */
        rw_max = min_not_zero(rw_max, sdp->host->opt_sectors);

        /* Do not exceed controller limit */
        rw_max = min(rw_max, queue_max_hw_sectors(q));

        /*
         * Only update max_sectors if previously unset or if the current value
         * exceeds the capabilities of the hardware.
         */
        if (sdkp->first_scan ||
            q->limits.max_sectors > q->limits.max_dev_sectors ||
            q->limits.max_sectors > q->limits.max_hw_sectors)
                q->limits.max_sectors = rw_max;

        sdkp->first_scan = 0;

        set_capacity_and_notify(disk, logical_to_sectors(sdp, sdkp->capacity));
        sd_config_write_same(sdkp);
        kfree(buffer);

        /*
         * For a zoned drive, revalidating the zones can be done only once
         * the gendisk capacity is set. So if this fails, set back the gendisk
         * capacity to 0.
         */
        if (sd_zbc_revalidate_zones(sdkp))
                set_capacity_and_notify(disk, 0);

 out:
        return 0;
}

/**
 *      sd_unlock_native_capacity - unlock native capacity
 *      @disk: struct gendisk to set capacity for
 *
 *      Block layer calls this function if it detects that partitions
 *      on @disk reach beyond the end of the device.  If the SCSI host
 *      implements ->unlock_native_capacity() method, it's invoked to
 *      give it a chance to adjust the device capacity.
 *
 *      CONTEXT:
 *      Defined by block layer.  Might sleep.
 */
static void sd_unlock_native_capacity(struct gendisk *disk)
{
        struct scsi_device *sdev = scsi_disk(disk)->device;

        if (sdev->host->hostt->unlock_native_capacity)
                sdev->host->hostt->unlock_native_capacity(sdev);
}

/**
 *      sd_format_disk_name - format disk name
 *      @prefix: name prefix - ie. "sd" for SCSI disks
 *      @index: index of the disk to format name for
 *      @buf: output buffer
 *      @buflen: length of the output buffer
 *
 *      SCSI disk names starts at sda.  The 26th device is sdz and the
 *      27th is sdaa.  The last one for two lettered suffix is sdzz
 *      which is followed by sdaaa.
 *
 *      This is basically 26 base counting with one extra 'nil' entry
 *      at the beginning from the second digit on and can be
 *      determined using similar method as 26 base conversion with the
 *      index shifted -1 after each digit is computed.
 *
 *      CONTEXT:
 *      Don't care.
 *
 *      RETURNS:
 *      0 on success, -errno on failure.
 */
static int sd_format_disk_name(char *prefix, int index, char *buf, int buflen)
{
        const int base = 'z' - 'a' + 1;
        char *begin = buf + strlen(prefix);
        char *end = buf + buflen;
        char *p;
        int unit;

        p = end - 1;
        *p = '\0';
        unit = base;
        do {
                if (p == begin)
                        return -EINVAL;
                *--p = 'a' + (index % unit);
                index = (index / unit) - 1;
        } while (index >= 0);

        memmove(begin, p, end - p);
        memcpy(buf, prefix, strlen(prefix));

        return 0;
}

/**
 *      sd_probe - called during driver initialization and whenever a
 *      new scsi device is attached to the system. It is called once
 *      for each scsi device (not just disks) present.
 *      @dev: pointer to device object
 *
 *      Returns 0 if successful (or not interested in this scsi device 
 *      (e.g. scanner)); 1 when there is an error.
 *
 *      Note: this function is invoked from the scsi mid-level.
 *      This function sets up the mapping between a given 
 *      <host,channel,id,lun> (found in sdp) and new device name 
 *      (e.g. /dev/sda). More precisely it is the block device major 
 *      and minor number that is chosen here.
 *
 *      Assume sd_probe is not re-entrant (for time being)
 *      Also think about sd_probe() and sd_remove() running coincidentally.
 **/
static int sd_probe(struct device *dev)
{
        struct scsi_device *sdp = to_scsi_device(dev);
        struct scsi_disk *sdkp;
        struct gendisk *gd;
        int index;
        int error;

        scsi_autopm_get_device(sdp);
        error = -ENODEV;
        if (sdp->type != TYPE_DISK &&
            sdp->type != TYPE_ZBC &&
            sdp->type != TYPE_MOD &&
            sdp->type != TYPE_RBC)
                goto out;

        if (!IS_ENABLED(CONFIG_BLK_DEV_ZONED) && sdp->type == TYPE_ZBC) {
                sdev_printk(KERN_WARNING, sdp,
                            "Unsupported ZBC host-managed device.\n");
                goto out;
        }

        SCSI_LOG_HLQUEUE(3, sdev_printk(KERN_INFO, sdp,
                                        "sd_probe\n"));

        error = -ENOMEM;
        sdkp = kzalloc(sizeof(*sdkp), GFP_KERNEL);
        if (!sdkp)
                goto out;

        gd = blk_mq_alloc_disk_for_queue(sdp->request_queue,
                                         &sd_bio_compl_lkclass);
        if (!gd)
                goto out_free;

        index = ida_alloc(&sd_index_ida, GFP_KERNEL);
        if (index < 0) {
                sdev_printk(KERN_WARNING, sdp, "sd_probe: memory exhausted.\n");
                goto out_put;
        }

        error = sd_format_disk_name("sd", index, gd->disk_name, DISK_NAME_LEN);
        if (error) {
                sdev_printk(KERN_WARNING, sdp, "SCSI disk (sd) name length exceeded.\n");
                goto out_free_index;
        }

        sdkp->device = sdp;
        sdkp->disk = gd;
        sdkp->index = index;
        sdkp->max_retries = SD_MAX_RETRIES;
        atomic_set(&sdkp->openers, 0);
        atomic_set(&sdkp->device->ioerr_cnt, 0);

        if (!sdp->request_queue->rq_timeout) {
                if (sdp->type != TYPE_MOD)
                        blk_queue_rq_timeout(sdp->request_queue, SD_TIMEOUT);
                else
                        blk_queue_rq_timeout(sdp->request_queue,
                                             SD_MOD_TIMEOUT);
        }

        device_initialize(&sdkp->disk_dev);
        sdkp->disk_dev.parent = get_device(dev);
        sdkp->disk_dev.class = &sd_disk_class;
        dev_set_name(&sdkp->disk_dev, "%s", dev_name(dev));

        error = device_add(&sdkp->disk_dev);
        if (error) {
                put_device(&sdkp->disk_dev);
                goto out;
        }

        dev_set_drvdata(dev, sdkp);

        gd->major = sd_major((index & 0xf0) >> 4);
        gd->first_minor = ((index & 0xf) << 4) | (index & 0xfff00);
        gd->minors = SD_MINORS;

        gd->fops = &sd_fops;
        gd->private_data = sdkp;

        /* defaults, until the device tells us otherwise */
        sdp->sector_size = 512;
        sdkp->capacity = 0;
        sdkp->media_present = 1;
        sdkp->write_prot = 0;
        sdkp->cache_override = 0;
        sdkp->WCE = 0;
        sdkp->RCD = 0;
        sdkp->ATO = 0;
        sdkp->first_scan = 1;
        sdkp->max_medium_access_timeouts = SD_MAX_MEDIUM_TIMEOUTS;

        sd_revalidate_disk(gd);

        if (sdp->removable) {
                gd->flags |= GENHD_FL_REMOVABLE;
                gd->events |= DISK_EVENT_MEDIA_CHANGE;
                gd->event_flags = DISK_EVENT_FLAG_POLL | DISK_EVENT_FLAG_UEVENT;
        }

        blk_pm_runtime_init(sdp->request_queue, dev);
        if (sdp->rpm_autosuspend) {
                pm_runtime_set_autosuspend_delay(dev,
                        sdp->host->hostt->rpm_autosuspend_delay);
        }

        error = device_add_disk(dev, gd, NULL);
        if (error) {
                put_device(&sdkp->disk_dev);
                put_disk(gd);
                goto out;
        }

        if (sdkp->security) {
                sdkp->opal_dev = init_opal_dev(sdkp, &sd_sec_submit);
                if (sdkp->opal_dev)
                        sd_printk(KERN_NOTICE, sdkp, "supports TCG Opal\n");
        }

        sd_printk(KERN_NOTICE, sdkp, "Attached SCSI %sdisk\n",
                  sdp->removable ? "removable " : "");
        scsi_autopm_put_device(sdp);

        return 0;

 out_free_index:
        ida_free(&sd_index_ida, index);
 out_put:
        put_disk(gd);
 out_free:
        kfree(sdkp);
 out:
        scsi_autopm_put_device(sdp);
        return error;
}

/**
 *      sd_remove - called whenever a scsi disk (previously recognized by
 *      sd_probe) is detached from the system. It is called (potentially
 *      multiple times) during sd module unload.
 *      @dev: pointer to device object
 *
 *      Note: this function is invoked from the scsi mid-level.
 *      This function potentially frees up a device name (e.g. /dev/sdc)
 *      that could be re-used by a subsequent sd_probe().
 *      This function is not called when the built-in sd driver is "exit-ed".
 **/
static int sd_remove(struct device *dev)
{
        struct scsi_disk *sdkp = dev_get_drvdata(dev);

        scsi_autopm_get_device(sdkp->device);

        device_del(&sdkp->disk_dev);
        del_gendisk(sdkp->disk);
        sd_shutdown(dev);

        put_disk(sdkp->disk);
        return 0;
}

static void scsi_disk_release(struct device *dev)
{
        struct scsi_disk *sdkp = to_scsi_disk(dev);

        ida_free(&sd_index_ida, sdkp->index);
        sd_zbc_free_zone_info(sdkp);
        put_device(&sdkp->device->sdev_gendev);
        free_opal_dev(sdkp->opal_dev);

        kfree(sdkp);
}

static int sd_start_stop_device(struct scsi_disk *sdkp, int start)
{
        unsigned char cmd[6] = { START_STOP };  /* START_VALID */
        struct scsi_sense_hdr sshdr;
        const struct scsi_exec_args exec_args = {
                .sshdr = &sshdr,
                .req_flags = BLK_MQ_REQ_PM,
        };
        struct scsi_device *sdp = sdkp->device;
        int res;

        if (start)
                cmd[4] |= 1;    /* START */

        if (sdp->start_stop_pwr_cond)
                cmd[4] |= start ? 1 << 4 : 3 << 4;      /* Active or Standby */

        if (!scsi_device_online(sdp))
                return -ENODEV;

        res = scsi_execute_cmd(sdp, cmd, REQ_OP_DRV_IN, NULL, 0, SD_TIMEOUT,
                               sdkp->max_retries, &exec_args);
        if (res) {
                sd_print_result(sdkp, "Start/Stop Unit failed", res);
                if (res > 0 && scsi_sense_valid(&sshdr)) {
                        sd_print_sense_hdr(sdkp, &sshdr);
                        /* 0x3a is medium not present */
                        if (sshdr.asc == 0x3a)
                                res = 0;
                }
        }

        /* SCSI error codes must not go to the generic layer */
        if (res)
                return -EIO;

        return 0;
}

/*
 * Send a SYNCHRONIZE CACHE instruction down to the device through
 * the normal SCSI command structure.  Wait for the command to
 * complete.
 */
static void sd_shutdown(struct device *dev)
{
        struct scsi_disk *sdkp = dev_get_drvdata(dev);

        if (!sdkp)
                return;         /* this can happen */

        if (pm_runtime_suspended(dev))
                return;

        if (sdkp->WCE && sdkp->media_present) {
                sd_printk(KERN_NOTICE, sdkp, "Synchronizing SCSI cache\n");
                sd_sync_cache(sdkp, NULL);
        }

        if (system_state != SYSTEM_RESTART && sdkp->device->manage_start_stop) {
                sd_printk(KERN_NOTICE, sdkp, "Stopping disk\n");
                sd_start_stop_device(sdkp, 0);
        }
}

static int sd_suspend_common(struct device *dev, bool ignore_stop_errors)
{
        struct scsi_disk *sdkp = dev_get_drvdata(dev);
        struct scsi_sense_hdr sshdr;
        int ret = 0;

        if (!sdkp)      /* E.g.: runtime suspend following sd_remove() */
                return 0;

        if (sdkp->WCE && sdkp->media_present) {
                if (!sdkp->device->silence_suspend)
                        sd_printk(KERN_NOTICE, sdkp, "Synchronizing SCSI cache\n");
                ret = sd_sync_cache(sdkp, &sshdr);

                if (ret) {
                        /* ignore OFFLINE device */
                        if (ret == -ENODEV)
                                return 0;

                        if (!scsi_sense_valid(&sshdr) ||
                            sshdr.sense_key != ILLEGAL_REQUEST)
                                return ret;

                        /*
                         * sshdr.sense_key == ILLEGAL_REQUEST means this drive
                         * doesn't support sync. There's not much to do and
                         * suspend shouldn't fail.
                         */
                        ret = 0;
                }
        }

        if (sdkp->device->manage_start_stop) {
                if (!sdkp->device->silence_suspend)
                        sd_printk(KERN_NOTICE, sdkp, "Stopping disk\n");
                /* an error is not worth aborting a system sleep */
                ret = sd_start_stop_device(sdkp, 0);
                if (ignore_stop_errors)
                        ret = 0;
        }

        return ret;
}

static int sd_suspend_system(struct device *dev)
{
        if (pm_runtime_suspended(dev))
                return 0;

        return sd_suspend_common(dev, true);
}

static int sd_suspend_runtime(struct device *dev)
{
        return sd_suspend_common(dev, false);
}

static int sd_resume(struct device *dev)
{
        struct scsi_disk *sdkp = dev_get_drvdata(dev);
        int ret = 0;

        if (!sdkp)      /* E.g.: runtime resume at the start of sd_probe() */
                return 0;

        if (!sdkp->device->manage_start_stop)
                return 0;

        if (!sdkp->device->no_start_on_resume) {
                sd_printk(KERN_NOTICE, sdkp, "Starting disk\n");
                ret = sd_start_stop_device(sdkp, 1);
        }

        if (!ret)
                opal_unlock_from_suspend(sdkp->opal_dev);
        return ret;
}

static int sd_resume_system(struct device *dev)
{
        if (pm_runtime_suspended(dev))
                return 0;

        return sd_resume(dev);
}

static int sd_resume_runtime(struct device *dev)
{
        struct scsi_disk *sdkp = dev_get_drvdata(dev);
        struct scsi_device *sdp;

        if (!sdkp)      /* E.g.: runtime resume at the start of sd_probe() */
                return 0;

        sdp = sdkp->device;

        if (sdp->ignore_media_change) {
                /* clear the device's sense data */
                static const u8 cmd[10] = { REQUEST_SENSE };
                const struct scsi_exec_args exec_args = {
                        .req_flags = BLK_MQ_REQ_PM,
                };

                if (scsi_execute_cmd(sdp, cmd, REQ_OP_DRV_IN, NULL, 0,
                                     sdp->request_queue->rq_timeout, 1,
                                     &exec_args))
                        sd_printk(KERN_NOTICE, sdkp,
                                  "Failed to clear sense data\n");
        }

        return sd_resume(dev);
}

static const struct dev_pm_ops sd_pm_ops = {
        .suspend                = sd_suspend_system,
        .resume                 = sd_resume_system,
        .poweroff               = sd_suspend_system,
        .restore                = sd_resume_system,
        .runtime_suspend        = sd_suspend_runtime,
        .runtime_resume         = sd_resume_runtime,
};

static struct scsi_driver sd_template = {
        .gendrv = {
                .name           = "sd",
                .owner          = THIS_MODULE,
                .probe          = sd_probe,
                .probe_type     = PROBE_PREFER_ASYNCHRONOUS,
                .remove         = sd_remove,
                .shutdown       = sd_shutdown,
                .pm             = &sd_pm_ops,
        },
        .rescan                 = sd_rescan,
        .init_command           = sd_init_command,
        .uninit_command         = sd_uninit_command,
        .done                   = sd_done,
        .eh_action              = sd_eh_action,
        .eh_reset               = sd_eh_reset,
};

/**
 *      init_sd - entry point for this driver (both when built in or when
 *      a module).
 *
 *      Note: this function registers this driver with the scsi mid-level.
 **/
static int __init init_sd(void)
{
        int majors = 0, i, err;

        SCSI_LOG_HLQUEUE(3, printk("init_sd: sd driver entry point\n"));

        for (i = 0; i < SD_MAJORS; i++) {
                if (__register_blkdev(sd_major(i), "sd", sd_default_probe))
                        continue;
                majors++;
        }

        if (!majors)
                return -ENODEV;

        err = class_register(&sd_disk_class);
        if (err)
                goto err_out;

        sd_page_pool = mempool_create_page_pool(SD_MEMPOOL_SIZE, 0);
        if (!sd_page_pool) {
                printk(KERN_ERR "sd: can't init discard page pool\n");
                err = -ENOMEM;
                goto err_out_class;
        }

        err = scsi_register_driver(&sd_template.gendrv);
        if (err)
                goto err_out_driver;

        return 0;

err_out_driver:
        mempool_destroy(sd_page_pool);
err_out_class:
        class_unregister(&sd_disk_class);
err_out:
        for (i = 0; i < SD_MAJORS; i++)
                unregister_blkdev(sd_major(i), "sd");
        return err;
}

/**
 *      exit_sd - exit point for this driver (when it is a module).
 *
 *      Note: this function unregisters this driver from the scsi mid-level.
 **/
static void __exit exit_sd(void)
{
        int i;

        SCSI_LOG_HLQUEUE(3, printk("exit_sd: exiting sd driver\n"));

        scsi_unregister_driver(&sd_template.gendrv);
        mempool_destroy(sd_page_pool);

        class_unregister(&sd_disk_class);

        for (i = 0; i < SD_MAJORS; i++)
                unregister_blkdev(sd_major(i), "sd");
}

module_init(init_sd);
module_exit(exit_sd);

void sd_print_sense_hdr(struct scsi_disk *sdkp, struct scsi_sense_hdr *sshdr)
{
        scsi_print_sense_hdr(sdkp->device,
                             sdkp->disk ? sdkp->disk->disk_name : NULL, sshdr);
}

void sd_print_result(const struct scsi_disk *sdkp, const char *msg, int result)
{
        const char *hb_string = scsi_hostbyte_string(result);

        if (hb_string)
                sd_printk(KERN_INFO, sdkp,
                          "%s: Result: hostbyte=%s driverbyte=%s\n", msg,
                          hb_string ? hb_string : "invalid",
                          "DRIVER_OK");
        else
                sd_printk(KERN_INFO, sdkp,
                          "%s: Result: hostbyte=0x%02x driverbyte=%s\n",
                          msg, host_byte(result), "DRIVER_OK");
}