// 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/genhd.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/mutex.h>
#include <linux/string_helpers.h>
#include <linux/async.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 "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 int  sd_probe(struct device *);
static int  sd_remove(struct device *);
static void sd_shutdown(struct device *);
static int sd_suspend_system(struct device *);
static int sd_suspend_runtime(struct device *);
static int sd_resume(struct device *);
static void sd_rescan(struct device *);
static blk_status_t sd_init_command(struct scsi_cmnd *SCpnt);
static void sd_uninit_command(struct scsi_cmnd *SCpnt);
static int sd_done(struct scsi_cmnd *);
static void sd_eh_reset(struct scsi_cmnd *);
static int sd_eh_action(struct scsi_cmnd *, int);
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);

/* This semaphore is used to mediate the 0->1 reference get in the
 * face of object destruction (i.e. we can't allow a get on an
 * object after last put) */
static DEFINE_MUTEX(sd_ref_mutex);

static struct kmem_cache *sd_cdb_cache;
static mempool_t *sd_cdb_pool;
static mempool_t *sd_page_pool;

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, 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, 8, 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",
        .owner          = THIS_MODULE,
        .dev_release    = scsi_disk_release,
        .dev_groups     = sd_disk_groups,
};

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

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,
};

/*
 * 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 */
        }
}

static struct scsi_disk *scsi_disk_get(struct gendisk *disk)
{
        struct scsi_disk *sdkp = NULL;

        mutex_lock(&sd_ref_mutex);

        if (disk->private_data) {
                sdkp = scsi_disk(disk);
                if (scsi_device_get(sdkp->device) == 0)
                        get_device(&sdkp->dev);
                else
                        sdkp = NULL;
        }
        mutex_unlock(&sd_ref_mutex);
        return sdkp;
}

static void scsi_disk_put(struct scsi_disk *sdkp)
{
        struct scsi_device *sdev = sdkp->device;

        mutex_lock(&sd_ref_mutex);
        put_device(&sdkp->dev);
        scsi_device_put(sdev);
        mutex_unlock(&sd_ref_mutex);
}

#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, };
        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(sdev, cdb, send ? DMA_TO_DEVICE : DMA_FROM_DEVICE,
                buffer, len, NULL, NULL, SD_TIMEOUT, sdkp->max_retries, 0,
                RQF_PM, NULL);
        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 bio *bio = scmd->request->bio;
        unsigned int prot_op = sd_prot_op(rq_data_dir(scmd->request), 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);
                blk_queue_flag_clear(QUEUE_FLAG_DISCARD, q);
                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));
        blk_queue_flag_set(QUEUE_FLAG_DISCARD, q);
}

static blk_status_t sd_setup_unmap_cmnd(struct scsi_cmnd *cmd)
{
        struct scsi_device *sdp = cmd->device;
        struct request *rq = cmd->request;
        struct scsi_disk *sdkp = scsi_disk(rq->rq_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;

        rq->special_vec.bv_page = mempool_alloc(sd_page_pool, GFP_ATOMIC);
        if (!rq->special_vec.bv_page)
                return BLK_STS_RESOURCE;
        clear_highpage(rq->special_vec.bv_page);
        rq->special_vec.bv_offset = 0;
        rq->special_vec.bv_len = data_len;
        rq->rq_flags |= RQF_SPECIAL_PAYLOAD;

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

        buf = page_address(rq->special_vec.bv_page);
        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 = cmd->request;
        struct scsi_disk *sdkp = scsi_disk(rq->rq_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;

        rq->special_vec.bv_page = mempool_alloc(sd_page_pool, GFP_ATOMIC);
        if (!rq->special_vec.bv_page)
                return BLK_STS_RESOURCE;
        clear_highpage(rq->special_vec.bv_page);
        rq->special_vec.bv_offset = 0;
        rq->special_vec.bv_len = data_len;
        rq->rq_flags |= RQF_SPECIAL_PAYLOAD;

        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 = cmd->request;
        struct scsi_disk *sdkp = scsi_disk(rq->rq_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;

        rq->special_vec.bv_page = mempool_alloc(sd_page_pool, GFP_ATOMIC);
        if (!rq->special_vec.bv_page)
                return BLK_STS_RESOURCE;
        clear_highpage(rq->special_vec.bv_page);
        rq->special_vec.bv_offset = 0;
        rq->special_vec.bv_len = data_len;
        rq->rq_flags |= RQF_SPECIAL_PAYLOAD;

        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 = cmd->request;
        struct scsi_device *sdp = cmd->device;
        struct scsi_disk *sdkp = scsi_disk(rq->rq_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() and __blkdev_issue_write_same()
                 * even if the caller of these 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_same_sectors(q, sdkp->max_ws_blocks *
                                         (logical_block_size >> 9));
        blk_queue_max_write_zeroes_sectors(q, sdkp->max_ws_blocks *
                                         (logical_block_size >> 9));
}

/**
 * sd_setup_write_same_cmnd - write the same data to multiple blocks
 * @cmd: command to prepare
 *
 * Will set up either WRITE SAME(10) or WRITE SAME(16) depending on
 * the preference indicated by the target device.
 **/
static blk_status_t sd_setup_write_same_cmnd(struct scsi_cmnd *cmd)
{
        struct request *rq = cmd->request;
        struct scsi_device *sdp = cmd->device;
        struct scsi_disk *sdkp = scsi_disk(rq->rq_disk);
        struct bio *bio = rq->bio;
        u64 lba = sectors_to_logical(sdp, blk_rq_pos(rq));
        u32 nr_blocks = sectors_to_logical(sdp, blk_rq_sectors(rq));
        blk_status_t ret;

        if (sdkp->device->no_write_same)
                return BLK_STS_TARGET;

        BUG_ON(bio_offset(bio) || bio_iovec(bio).bv_len != sdp->sector_size);

        rq->timeout = SD_WRITE_SAME_TIMEOUT;

        if (sdkp->ws16 || lba > 0xffffffff || nr_blocks > 0xffff) {
                cmd->cmd_len = 16;
                cmd->cmnd[0] = WRITE_SAME_16;
                put_unaligned_be64(lba, &cmd->cmnd[2]);
                put_unaligned_be32(nr_blocks, &cmd->cmnd[10]);
        } else {
                cmd->cmd_len = 10;
                cmd->cmnd[0] = WRITE_SAME;
                put_unaligned_be32(lba, &cmd->cmnd[2]);
                put_unaligned_be16(nr_blocks, &cmd->cmnd[7]);
        }

        cmd->transfersize = sdp->sector_size;
        cmd->allowed = sdkp->max_retries;

        /*
         * For WRITE SAME the data transferred via the DATA OUT buffer is
         * different from the amount of data actually written to the target.
         *
         * We set up __data_len to the amount of data transferred via the
         * DATA OUT buffer so that blk_rq_map_sg sets up the proper S/G list
         * to transfer a single sector of data first, but then reset it to
         * the amount of data to be written right after so that the I/O path
         * knows how much to actually write.
         */
        rq->__data_len = sdp->sector_size;
        ret = scsi_alloc_sgtables(cmd);
        rq->__data_len = blk_rq_bytes(rq);

        return ret;
}

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

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

        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)
{
        cmd->cmnd = mempool_alloc(sd_cdb_pool, GFP_ATOMIC);
        if (unlikely(cmd->cmnd == NULL))
                return BLK_STS_RESOURCE;

        cmd->cmd_len = SD_EXT_CDB_SIZE;
        memset(cmd->cmnd, 0, cmd->cmd_len);

        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;
        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)
{
        cmd->cmd_len  = 16;
        cmd->cmnd[0]  = write ? WRITE_16 : READ_16;
        cmd->cmnd[1]  = flags;
        cmd->cmnd[14] = 0;
        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;
}

static blk_status_t sd_setup_read_write_cmnd(struct scsi_cmnd *cmd)
{
        struct request *rq = cmd->request;
        struct scsi_device *sdp = cmd->device;
        struct scsi_disk *sdkp = scsi_disk(rq->rq_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;
        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->rq_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);

        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);
        } else if (sdp->use_16_for_rw || (nr_blocks > 0xffff)) {
                ret = sd_setup_rw16_cmnd(cmd, write, lba, nr_blocks,
                                         protect | fua);
        } 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 = cmd->request;

        switch (req_op(rq)) {
        case REQ_OP_DISCARD:
                switch (scsi_disk(rq->rq_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_WRITE_SAME:
                return sd_setup_write_same_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 = SCpnt->request;
        u8 *cmnd;

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

        if (SCpnt->cmnd != scsi_req(rq)->cmd) {
                cmnd = SCpnt->cmnd;
                SCpnt->cmnd = NULL;
                SCpnt->cmd_len = 0;
                mempool_free(cmnd, sd_cdb_pool);
        }
}

static bool sd_need_revalidate(struct block_device *bdev,
                struct scsi_disk *sdkp)
{
        if (sdkp->device->removable || sdkp->write_prot) {
                if (bdev_check_media_change(bdev))
                        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, &bdev->bd_disk->state);
}

/**
 *      sd_open - open a scsi disk device
 *      @bdev: Block device of the scsi disk to open
 *      @mode: FMODE_* mask
 *
 *      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 bdev->bd_disk->open_mutex held.
 **/
static int sd_open(struct block_device *bdev, fmode_t mode)
{
        struct scsi_disk *sdkp = scsi_disk_get(bdev->bd_disk);
        struct scsi_device *sdev;
        int retval;

        if (!sdkp)
                return -ENXIO;

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

        sdev = sdkp->device;

        /*
         * 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(bdev, sdkp))
                sd_revalidate_disk(bdev->bd_disk);

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

/**
 *      sd_release - invoked when the (last) close(2) is called on this
 *      scsi disk.
 *      @disk: disk to release
 *      @mode: FMODE_* mask
 *
 *      Returns 0. 
 *
 *      Note: may block (uninterruptible) if error recovery is underway
 *      on this disk.
 *
 *      Locking: called with bdev->bd_disk->open_mutex held.
 **/
static void sd_release(struct gendisk *disk, fmode_t mode)
{
        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_disk_put(sdkp);
}

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_common - process an ioctl
 *      @bdev: target block device
 *      @mode: FMODE_* mask
 *      @cmd: ioctl command number
 *      @p: 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_common(struct block_device *bdev, fmode_t mode,
                           unsigned int cmd, void __user *p)
{
        struct gendisk *disk = bdev->bd_disk;
        struct scsi_disk *sdkp = scsi_disk(disk);
        struct scsi_device *sdp = sdkp->device;
        int error;
    
        SCSI_LOG_IOCTL(1, sd_printk(KERN_INFO, sdkp, "sd_ioctl: disk=%s, "
                                    "cmd=0x%x\n", disk->disk_name, cmd));

        error = scsi_verify_blk_ioctl(bdev, cmd);
        if (error < 0)
                return error;

        /*
         * 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 & FMODE_NDELAY) != 0);
        if (error)
                goto out;

        if (is_sed_ioctl(cmd))
                return sed_ioctl(sdkp->opal_dev, cmd, p);

        /*
         * Send SCSI addressing ioctls directly to mid level, send other
         * ioctls to block level and then onto mid level if they can't be
         * resolved.
         */
        switch (cmd) {
                case SCSI_IOCTL_GET_IDLUN:
                case SCSI_IOCTL_GET_BUS_NUMBER:
                        error = scsi_ioctl(sdp, cmd, p);
                        break;
                default:
                        error = scsi_cmd_blk_ioctl(bdev, mode, cmd, p);
                        break;
        }
out:
        return error;
}

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 = scsi_disk_get(disk);
        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;
        scsi_disk_put(sdkp);
        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;

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

        /* caller might not be interested in sense, but we need it */
        if (!sshdr)
                sshdr = &my_sshdr;

        for (retries = 3; retries > 0; --retries) {
                unsigned char cmd[10] = { 0 };

                cmd[0] = SYNCHRONIZE_CACHE;
                /*
                 * Leave the rest of the command zero to indicate
                 * flush everything.
                 */
                res = scsi_execute(sdp, cmd, DMA_NONE, NULL, 0, NULL, sshdr,
                                timeout, sdkp->max_retries, 0, RQF_PM, NULL);
                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_ioctl(struct block_device *bdev, fmode_t mode,
                    unsigned int cmd, unsigned long arg)
{
        void __user *p = (void __user *)arg;
        int ret;

        ret = sd_ioctl_common(bdev, mode, cmd, p);
        if (ret != -ENOTTY)
                return ret;

        return scsi_ioctl(scsi_disk(bdev->bd_disk)->device, cmd, p);
}

#ifdef CONFIG_COMPAT
static int sd_compat_ioctl(struct block_device *bdev, fmode_t mode,
                           unsigned int cmd, unsigned long arg)
{
        void __user *p = compat_ptr(arg);
        int ret;

        ret = sd_ioctl_common(bdev, mode, cmd, p);
        if (ret != -ENOTTY)
                return ret;

        return scsi_compat_ioctl(scsi_disk(bdev->bd_disk)->device, cmd, p);
}
#endif

static char sd_pr_type(enum pr_type type)
{
        switch (type) {
        case PR_WRITE_EXCLUSIVE:
                return 0x01;
        case PR_EXCLUSIVE_ACCESS:
                return 0x03;
        case PR_WRITE_EXCLUSIVE_REG_ONLY:
                return 0x05;
        case PR_EXCLUSIVE_ACCESS_REG_ONLY:
                return 0x06;
        case PR_WRITE_EXCLUSIVE_ALL_REGS:
                return 0x07;
        case PR_EXCLUSIVE_ACCESS_ALL_REGS:
                return 0x08;
        default:
                return 0;
        }
};

static int sd_pr_command(struct block_device *bdev, u8 sa,
                u64 key, u64 sa_key, u8 type, u8 flags)
{
        struct scsi_disk *sdkp = scsi_disk(bdev->bd_disk);
        struct scsi_device *sdev = sdkp->device;
        struct scsi_sense_hdr 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_req(sdev, cmd, DMA_TO_DEVICE, &data, sizeof(data),
                        &sshdr, SD_TIMEOUT, sdkp->max_retries, NULL);

        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);
        }

        return 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_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_command(bdev, 0x01, key, 0, sd_pr_type(type), 0);
}

static int sd_pr_release(struct block_device *bdev, u64 key, enum pr_type type)
{
        return sd_pr_command(bdev, 0x02, key, 0, sd_pr_type(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_command(bdev, abort ? 0x05 : 0x04, old_key, new_key,
                             sd_pr_type(type), 0);
}

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

static const struct block_device_operations sd_fops = {
        .owner                  = THIS_MODULE,
        .open                   = sd_open,
        .release                = sd_release,
        .ioctl                  = sd_ioctl,
        .getgeo                 = sd_getgeo,
#ifdef CONFIG_COMPAT
        .compat_ioctl           = sd_compat_ioctl,
#endif
        .check_events           = sd_check_events,
        .unlock_native_capacity = sd_unlock_native_capacity,
        .report_zones           = sd_zbc_report_zones,
        .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(scmd->request->rq_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(scmd->request->rq_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 = scmd->request;
        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 scsi_disk *sdkp = scsi_disk(SCpnt->request->rq_disk);
        struct request *req = SCpnt->request;
        int sense_valid = 0;
        int sense_deferred = 0;

        switch (req_op(req)) {
        case REQ_OP_DISCARD:
        case REQ_OP_WRITE_ZEROES:
        case REQ_OP_WRITE_SAME:
        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;
        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 {
                        cmd[0] = TEST_UNIT_READY;
                        memset((void *) &cmd[1], 0, 9);

                        the_result = scsi_execute_req(sdkp->device, cmd,
                                                      DMA_NONE, NULL, 0,
                                                      &sshdr, SD_TIMEOUT,
                                                      sdkp->max_retries, NULL);

                        /*
                         * 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))
                                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_req(sdkp->device, cmd, DMA_NONE,
                                                 NULL, 0, &sshdr,
                                                 SD_TIMEOUT, sdkp->max_retries,
                                                 NULL);
                                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;
        int ret = 0;

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

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

        if (type > T10_PI_TYPE3_PROTECTION)
                ret = -ENODEV;
        else if (scsi_host_dif_capable(sdp->host, type))
                ret = 1;

        if (sdkp->first_scan || type != sdkp->protection_type)
                switch (ret) {
                case -ENODEV:
                        sd_printk(KERN_ERR, sdkp, "formatted with unsupported" \
                                  " protection type %u. Disabling disk!\n",
                                  type);
                        break;
                case 1:
                        sd_printk(KERN_NOTICE, sdkp,
                                  "Enabling DIF Type %u protection\n", type);
                        break;
                case 0:
                        sd_printk(KERN_NOTICE, sdkp,
                                  "Disabling DIF Type %u protection\n", type);
                        break;
                }

        sdkp->protection_type = type;

        return ret;
}

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;
        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_req(sdp, cmd, DMA_FROM_DEVICE,
                                        buffer, RC16_LEN, &sshdr,
                                        SD_TIMEOUT, sdkp->max_retries, NULL);

                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;
        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_req(sdp, cmd, DMA_FROM_DEVICE,
                                        buffer, 8, &sshdr,
                                        SD_TIMEOUT, sdkp->max_retries, NULL);

                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)
{
        return scsi_mode_sense(sdkp->device, dbd, modepage, 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_ERR, 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_ERR, 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, 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)
{
        unsigned int sector_sz = sdkp->device->sector_size;
        const int vpd_len = 64;
        unsigned char *buffer = kmalloc(vpd_len, GFP_KERNEL);

        if (!buffer ||
            /* Block Limits VPD */
            scsi_get_vpd_page(sdkp->device, 0xb0, buffer, vpd_len))
                goto out;

        blk_queue_io_min(sdkp->disk->queue,
                         get_unaligned_be16(&buffer[6]) * sector_sz);

        sdkp->max_xfer_blocks = get_unaligned_be32(&buffer[8]);
        sdkp->opt_xfer_blocks = get_unaligned_be32(&buffer[12]);

        if (buffer[3] == 0x3c) {
                unsigned int lba_count, desc_count;

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

                if (!sdkp->lbpme)
                        goto out;

                lba_count = get_unaligned_be32(&buffer[20]);
                desc_count = get_unaligned_be32(&buffer[24]);

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

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

                if (buffer[32] & 0x80)
                        sdkp->unmap_alignment =
                                get_unaligned_be32(&buffer[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:
        kfree(buffer);
}

/**
 * sd_read_block_characteristics - Query block dev. characteristics