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	Version: linux-6.0.1 spark-3.0.0 hadoop-3.2.0-src hadoop-3.3.0-src spark-2.4.7 linux-4.15.13 hadoop-2.7.4-src Revert   Change

 // SPDX-License-Identifier: GPL-2.0-or-later
 /*
  *  History:
  *  Started: Aug 9 by Lawrence Foard (entropy@world.std.com),
  *           to allow user process control of SCSI devices.
  *  Development Sponsored by Killy Corp. NY NY
  *
  * Original driver (sg.c):
  *        Copyright (C) 1992 Lawrence Foard
  * Version 2 and 3 extensions to driver:
  *        Copyright (C) 1998 - 2014 Douglas Gilbert
  */
 
 static int sg_version_num = 30536;  /* 2 digits for each component */
 #define SG_VERSION_STR "3.5.36"
 
 /*
  *  D. P. Gilbert (dgilbert@interlog.com), notes:
  *      - scsi logging is available via SCSI_LOG_TIMEOUT macros. First
  *        the kernel/module needs to be built with CONFIG_SCSI_LOGGING
  *        (otherwise the macros compile to empty statements).
  *
  */
 #include <linux/module.h>
 
 #include <linux/fs.h>
 #include <linux/kernel.h>
 #include <linux/sched.h>
 #include <linux/string.h>
 #include <linux/mm.h>
 #include <linux/errno.h>
 #include <linux/mtio.h>
 #include <linux/ioctl.h>
 #include <linux/major.h>
 #include <linux/slab.h>
 #include <linux/fcntl.h>
 #include <linux/init.h>
 #include <linux/poll.h>
 #include <linux/moduleparam.h>
 #include <linux/cdev.h>
 #include <linux/idr.h>
 #include <linux/seq_file.h>
 #include <linux/blkdev.h>
 #include <linux/delay.h>
 #include <linux/blktrace_api.h>
 #include <linux/mutex.h>
 #include <linux/atomic.h>
 #include <linux/ratelimit.h>
 #include <linux/uio.h>
 #include <linux/cred.h> /* for sg_check_file_access() */
 
 #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/scsi_tcq.h>
 #include <scsi/sg.h>
 
 #include "scsi_logging.h"
 
 #ifdef CONFIG_SCSI_PROC_FS
 #include <linux/proc_fs.h>
 static char *sg_version_date = "20140603";
 
 static int sg_proc_init(void);
 #endif
 
 #define SG_ALLOW_DIO_DEF 0
 
 #define SG_MAX_DEVS 32768
 
 /* SG_MAX_CDB_SIZE should be 260 (spc4r37 section 3.1.30) however the type
  * of sg_io_hdr::cmd_len can only represent 255. All SCSI commands greater
  * than 16 bytes are "variable length" whose length is a multiple of 4
  */
 #define SG_MAX_CDB_SIZE 252
 
 #define SG_DEFAULT_TIMEOUT mult_frac(SG_DEFAULT_TIMEOUT_USER, HZ, USER_HZ)
 
 static int sg_big_buff = SG_DEF_RESERVED_SIZE;
 /* N.B. This variable is readable and writeable via
    /proc/scsi/sg/def_reserved_size . Each time sg_open() is called a buffer
    of this size (or less if there is not enough memory) will be reserved
    for use by this file descriptor. [Deprecated usage: this variable is also
    readable via /proc/sys/kernel/sg-big-buff if the sg driver is built into
    the kernel (i.e. it is not a module).] */
 static int def_reserved_size = -1;  /* picks up init parameter */
 static int sg_allow_dio = SG_ALLOW_DIO_DEF;
 
 static int scatter_elem_sz = SG_SCATTER_SZ;
 static int scatter_elem_sz_prev = SG_SCATTER_SZ;
 
 #define SG_SECTOR_SZ 512
 
 static int sg_add_device(struct device *, struct class_interface *);
 static void sg_remove_device(struct device *, struct class_interface *);
 
 static DEFINE_IDR(sg_index_idr);
 static DEFINE_RWLOCK(sg_index_lock);    /* Also used to lock
                                file descriptor list for device */
 
 static struct class_interface sg_interface = {
     .add_dev        = sg_add_device,
     .remove_dev     = sg_remove_device,
 };
 
 typedef struct sg_scatter_hold { /* holding area for scsi scatter gather info */
     unsigned short k_use_sg; /* Count of kernel scatter-gather pieces */
     unsigned sglist_len; /* size of malloc'd scatter-gather list ++ */
     unsigned bufflen;   /* Size of (aggregate) data buffer */
     struct page **pages;
     int page_order;
     char dio_in_use;    /* 0->indirect IO (or mmap), 1->dio */
     unsigned char cmd_opcode; /* first byte of command */
 } Sg_scatter_hold;
 
 struct sg_device;       /* forward declarations */
 struct sg_fd;
 
 typedef struct sg_request { /* SG_MAX_QUEUE requests outstanding per file */
     struct list_head entry; /* list entry */
     struct sg_fd *parentfp; /* NULL -> not in use */
     Sg_scatter_hold data;   /* hold buffer, perhaps scatter list */
     sg_io_hdr_t header; /* scsi command+info, see <scsi/sg.h> */
     unsigned char sense_b[SCSI_SENSE_BUFFERSIZE];
     char res_used;      /* 1 -> using reserve buffer, 0 -> not ... */
     char orphan;        /* 1 -> drop on sight, 0 -> normal */
     char sg_io_owned;   /* 1 -> packet belongs to SG_IO */
     /* done protected by rq_list_lock */
     char done;      /* 0->before bh, 1->before read, 2->read */
     struct request *rq;
     struct bio *bio;
     struct execute_work ew;
 } Sg_request;
 
 typedef struct sg_fd {      /* holds the state of a file descriptor */
     struct list_head sfd_siblings;  /* protected by device's sfd_lock */
     struct sg_device *parentdp; /* owning device */
     wait_queue_head_t read_wait;    /* queue read until command done */
     rwlock_t rq_list_lock;  /* protect access to list in req_arr */
     struct mutex f_mutex;   /* protect against changes in this fd */
     int timeout;        /* defaults to SG_DEFAULT_TIMEOUT      */
     int timeout_user;   /* defaults to SG_DEFAULT_TIMEOUT_USER */
     Sg_scatter_hold reserve;    /* buffer held for this file descriptor */
     struct list_head rq_list; /* head of request list */
     struct fasync_struct *async_qp; /* used by asynchronous notification */
     Sg_request req_arr[SG_MAX_QUEUE];   /* used as singly-linked list */
     char force_packid;  /* 1 -> pack_id input to read(), 0 -> ignored */
     char cmd_q;     /* 1 -> allow command queuing, 0 -> don't */
     unsigned char next_cmd_len; /* 0: automatic, >0: use on next write() */
     char keep_orphan;   /* 0 -> drop orphan (def), 1 -> keep for read() */
     char mmap_called;   /* 0 -> mmap() never called on this fd */
     char res_in_use;    /* 1 -> 'reserve' array in use */
     struct kref f_ref;
     struct execute_work ew;
 } Sg_fd;
 
 typedef struct sg_device { /* holds the state of each scsi generic device */
     struct scsi_device *device;
     wait_queue_head_t open_wait;    /* queue open() when O_EXCL present */
     struct mutex open_rel_lock;     /* held when in open() or release() */
     int sg_tablesize;   /* adapter's max scatter-gather table size */
     u32 index;      /* device index number */
     struct list_head sfds;
     rwlock_t sfd_lock;      /* protect access to sfd list */
     atomic_t detaching;     /* 0->device usable, 1->device detaching */
     bool exclude;       /* 1->open(O_EXCL) succeeded and is active */
     int open_cnt;       /* count of opens (perhaps < num(sfds) ) */
     char sgdebug;       /* 0->off, 1->sense, 9->dump dev, 10-> all devs */
     char name[DISK_NAME_LEN];
     struct cdev * cdev; /* char_dev [sysfs: /sys/cdev/major/sg<n>] */
     struct kref d_ref;
 } Sg_device;
 
 /* tasklet or soft irq callback */
 static void sg_rq_end_io(struct request *rq, blk_status_t status);
 static int sg_start_req(Sg_request *srp, unsigned char *cmd);
 static int sg_finish_rem_req(Sg_request * srp);
 static int sg_build_indirect(Sg_scatter_hold * schp, Sg_fd * sfp, int buff_size);
 static ssize_t sg_new_read(Sg_fd * sfp, char __user *buf, size_t count,
                Sg_request * srp);
 static ssize_t sg_new_write(Sg_fd *sfp, struct file *file,
             const char __user *buf, size_t count, int blocking,
             int read_only, int sg_io_owned, Sg_request **o_srp);
 static int sg_common_write(Sg_fd * sfp, Sg_request * srp,
                unsigned char *cmnd, int timeout, int blocking);
 static int sg_read_oxfer(Sg_request * srp, char __user *outp, int num_read_xfer);
 static void sg_remove_scat(Sg_fd * sfp, Sg_scatter_hold * schp);
 static void sg_build_reserve(Sg_fd * sfp, int req_size);
 static void sg_link_reserve(Sg_fd * sfp, Sg_request * srp, int size);
 static void sg_unlink_reserve(Sg_fd * sfp, Sg_request * srp);
 static Sg_fd *sg_add_sfp(Sg_device * sdp);
 static void sg_remove_sfp(struct kref *);
 static Sg_request *sg_get_rq_mark(Sg_fd * sfp, int pack_id, bool *busy);
 static Sg_request *sg_add_request(Sg_fd * sfp);
 static int sg_remove_request(Sg_fd * sfp, Sg_request * srp);
 static Sg_device *sg_get_dev(int dev);
 static void sg_device_destroy(struct kref *kref);
 
 #define SZ_SG_HEADER sizeof(struct sg_header)
 #define SZ_SG_IO_HDR sizeof(sg_io_hdr_t)
 #define SZ_SG_IOVEC sizeof(sg_iovec_t)
 #define SZ_SG_REQ_INFO sizeof(sg_req_info_t)
 
 #define sg_printk(prefix, sdp, fmt, a...) \
     sdev_prefix_printk(prefix, (sdp)->device, (sdp)->name, fmt, ##a)
 
 /*
  * The SCSI interfaces that use read() and write() as an asynchronous variant of
  * ioctl(..., SG_IO, ...) are fundamentally unsafe, since there are lots of ways
  * to trigger read() and write() calls from various contexts with elevated
  * privileges. This can lead to kernel memory corruption (e.g. if these
  * interfaces are called through splice()) and privilege escalation inside
  * userspace (e.g. if a process with access to such a device passes a file
  * descriptor to a SUID binary as stdin/stdout/stderr).
  *
  * This function provides protection for the legacy API by restricting the
  * calling context.
  */
 static int sg_check_file_access(struct file *filp, const char *caller)
 {
     if (filp->f_cred != current_real_cred()) {
         pr_err_once("%s: process %d (%s) changed security contexts after opening file descriptor, this is not allowed.\n",
             caller, task_tgid_vnr(current), current->comm);
         return -EPERM;
     }
     return 0;
 }
 
 static int sg_allow_access(struct file *filp, unsigned char *cmd)
 {
     struct sg_fd *sfp = filp->private_data;
 
     if (sfp->parentdp->device->type == TYPE_SCANNER)
         return 0;
     if (!scsi_cmd_allowed(cmd, filp->f_mode))
         return -EPERM;
     return 0;
 }
 
 static int
 open_wait(Sg_device *sdp, int flags)
 {
     int retval = 0;
 
     if (flags & O_EXCL) {
         while (sdp->open_cnt > 0) {
             mutex_unlock(&sdp->open_rel_lock);
             retval = wait_event_interruptible(sdp->open_wait,
                     (atomic_read(&sdp->detaching) ||
                      !sdp->open_cnt));
             mutex_lock(&sdp->open_rel_lock);
 
             if (retval) /* -ERESTARTSYS */
                 return retval;
             if (atomic_read(&sdp->detaching))
                 return -ENODEV;
         }
     } else {
         while (sdp->exclude) {
             mutex_unlock(&sdp->open_rel_lock);
             retval = wait_event_interruptible(sdp->open_wait,
                     (atomic_read(&sdp->detaching) ||
                      !sdp->exclude));
             mutex_lock(&sdp->open_rel_lock);
 
             if (retval) /* -ERESTARTSYS */
                 return retval;
             if (atomic_read(&sdp->detaching))
                 return -ENODEV;
         }
     }
 
     return retval;
 }
 
 /* Returns 0 on success, else a negated errno value */
 static int
 sg_open(struct inode *inode, struct file *filp)
 {
     int dev = iminor(inode);
     int flags = filp->f_flags;
     struct request_queue *q;
     Sg_device *sdp;
     Sg_fd *sfp;
     int retval;
 
     nonseekable_open(inode, filp);
     if ((flags & O_EXCL) && (O_RDONLY == (flags & O_ACCMODE)))
         return -EPERM; /* Can't lock it with read only access */
     sdp = sg_get_dev(dev);
     if (IS_ERR(sdp))
         return PTR_ERR(sdp);
 
     SCSI_LOG_TIMEOUT(3, sg_printk(KERN_INFO, sdp,
                       "sg_open: flags=0x%x\n", flags));
 
     /* This driver's module count bumped by fops_get in <linux/fs.h> */
     /* Prevent the device driver from vanishing while we sleep */
     retval = scsi_device_get(sdp->device);
     if (retval)
         goto sg_put;
 
     retval = scsi_autopm_get_device(sdp->device);
     if (retval)
         goto sdp_put;
 
     /* scsi_block_when_processing_errors() may block so bypass
      * check if O_NONBLOCK. Permits SCSI commands to be issued
      * during error recovery. Tread carefully. */
     if (!((flags & O_NONBLOCK) ||
           scsi_block_when_processing_errors(sdp->device))) {
         retval = -ENXIO;
         /* we are in error recovery for this device */
         goto error_out;
     }
 
     mutex_lock(&sdp->open_rel_lock);
     if (flags & O_NONBLOCK) {
         if (flags & O_EXCL) {
             if (sdp->open_cnt > 0) {
                 retval = -EBUSY;
                 goto error_mutex_locked;
             }
         } else {
             if (sdp->exclude) {
                 retval = -EBUSY;
                 goto error_mutex_locked;
             }
         }
     } else {
         retval = open_wait(sdp, flags);
         if (retval) /* -ERESTARTSYS or -ENODEV */
             goto error_mutex_locked;
     }
 
     /* N.B. at this point we are holding the open_rel_lock */
     if (flags & O_EXCL)
         sdp->exclude = true;
 
     if (sdp->open_cnt < 1) {  /* no existing opens */
         sdp->sgdebug = 0;
         q = sdp->device->request_queue;
         sdp->sg_tablesize = queue_max_segments(q);
     }
     sfp = sg_add_sfp(sdp);
     if (IS_ERR(sfp)) {
         retval = PTR_ERR(sfp);
         goto out_undo;
     }
 
     filp->private_data = sfp;
     sdp->open_cnt++;
     mutex_unlock(&sdp->open_rel_lock);
 
     retval = 0;
 sg_put:
     kref_put(&sdp->d_ref, sg_device_destroy);
     return retval;
 
 out_undo:
     if (flags & O_EXCL) {
         sdp->exclude = false;   /* undo if error */
         wake_up_interruptible(&sdp->open_wait);
     }
 error_mutex_locked:
     mutex_unlock(&sdp->open_rel_lock);
 error_out:
     scsi_autopm_put_device(sdp->device);
 sdp_put:
     scsi_device_put(sdp->device);
     goto sg_put;
 }
 
 /* Release resources associated with a successful sg_open()
  * Returns 0 on success, else a negated errno value */
 static int
 sg_release(struct inode *inode, struct file *filp)
 {
     Sg_device *sdp;
     Sg_fd *sfp;
 
     if ((!(sfp = (Sg_fd *) filp->private_data)) || (!(sdp = sfp->parentdp)))
         return -ENXIO;
     SCSI_LOG_TIMEOUT(3, sg_printk(KERN_INFO, sdp, "sg_release\n"));
 
     mutex_lock(&sdp->open_rel_lock);
     scsi_autopm_put_device(sdp->device);
     kref_put(&sfp->f_ref, sg_remove_sfp);
     sdp->open_cnt--;
 
     /* possibly many open()s waiting on exlude clearing, start many;
      * only open(O_EXCL)s wait on 0==open_cnt so only start one */
     if (sdp->exclude) {
         sdp->exclude = false;
         wake_up_interruptible_all(&sdp->open_wait);
     } else if (0 == sdp->open_cnt) {
         wake_up_interruptible(&sdp->open_wait);
     }
     mutex_unlock(&sdp->open_rel_lock);
     return 0;
 }
 
 static int get_sg_io_pack_id(int *pack_id, void __user *buf, size_t count)
 {
     struct sg_header __user *old_hdr = buf;
     int reply_len;
 
     if (count >= SZ_SG_HEADER) {
         /* negative reply_len means v3 format, otherwise v1/v2 */
         if (get_user(reply_len, &old_hdr->reply_len))
             return -EFAULT;
 
         if (reply_len >= 0)
             return get_user(*pack_id, &old_hdr->pack_id);
 
         if (in_compat_syscall() &&
             count >= sizeof(struct compat_sg_io_hdr)) {
             struct compat_sg_io_hdr __user *hp = buf;
 
             return get_user(*pack_id, &hp->pack_id);
         }
 
         if (count >= sizeof(struct sg_io_hdr)) {
             struct sg_io_hdr __user *hp = buf;
 
             return get_user(*pack_id, &hp->pack_id);
         }
     }
 
     /* no valid header was passed, so ignore the pack_id */
     *pack_id = -1;
     return 0;
 }
 
 static ssize_t
 sg_read(struct file *filp, char __user *buf, size_t count, loff_t * ppos)
 {
     Sg_device *sdp;
     Sg_fd *sfp;
     Sg_request *srp;
     int req_pack_id = -1;
     bool busy;
     sg_io_hdr_t *hp;
     struct sg_header *old_hdr;
     int retval;
 
     /*
      * This could cause a response to be stranded. Close the associated
      * file descriptor to free up any resources being held.
      */
     retval = sg_check_file_access(filp, __func__);
     if (retval)
         return retval;
 
     if ((!(sfp = (Sg_fd *) filp->private_data)) || (!(sdp = sfp->parentdp)))
         return -ENXIO;
     SCSI_LOG_TIMEOUT(3, sg_printk(KERN_INFO, sdp,
                       "sg_read: count=%d\n", (int) count));
 
     if (sfp->force_packid)
         retval = get_sg_io_pack_id(&req_pack_id, buf, count);
     if (retval)
         return retval;
 
     srp = sg_get_rq_mark(sfp, req_pack_id, &busy);
     if (!srp) {     /* now wait on packet to arrive */
         if (filp->f_flags & O_NONBLOCK)
             return -EAGAIN;
         retval = wait_event_interruptible(sfp->read_wait,
             ((srp = sg_get_rq_mark(sfp, req_pack_id, &busy)) ||
             (!busy && atomic_read(&sdp->detaching))));
         if (!srp)
             /* signal or detaching */
             return retval ? retval : -ENODEV;
     }
     if (srp->header.interface_id != '\0')
         return sg_new_read(sfp, buf, count, srp);
 
     hp = &srp->header;
     old_hdr = kzalloc(SZ_SG_HEADER, GFP_KERNEL);
     if (!old_hdr)
         return -ENOMEM;
 
     old_hdr->reply_len = (int) hp->timeout;
     old_hdr->pack_len = old_hdr->reply_len; /* old, strange behaviour */
     old_hdr->pack_id = hp->pack_id;
     old_hdr->twelve_byte =
         ((srp->data.cmd_opcode >= 0xc0) && (12 == hp->cmd_len)) ? 1 : 0;
     old_hdr->target_status = hp->masked_status;
     old_hdr->host_status = hp->host_status;
     old_hdr->driver_status = hp->driver_status;
     if ((CHECK_CONDITION & hp->masked_status) ||
         (srp->sense_b[0] & 0x70) == 0x70) {
         old_hdr->driver_status = DRIVER_SENSE;
         memcpy(old_hdr->sense_buffer, srp->sense_b,
                sizeof (old_hdr->sense_buffer));
     }
     switch (hp->host_status) {
     /* This setup of 'result' is for backward compatibility and is best
        ignored by the user who should use target, host + driver status */
     case DID_OK:
     case DID_PASSTHROUGH:
     case DID_SOFT_ERROR:
         old_hdr->result = 0;
         break;
     case DID_NO_CONNECT:
     case DID_BUS_BUSY:
     case DID_TIME_OUT:
         old_hdr->result = EBUSY;
         break;
     case DID_BAD_TARGET:
     case DID_ABORT:
     case DID_PARITY:
     case DID_RESET:
     case DID_BAD_INTR:
         old_hdr->result = EIO;
         break;
     case DID_ERROR:
         old_hdr->result = (srp->sense_b[0] == 0 && 
                   hp->masked_status == GOOD) ? 0 : EIO;
         break;
     default:
         old_hdr->result = EIO;
         break;
     }
 
     /* Now copy the result back to the user buffer.  */
     if (count >= SZ_SG_HEADER) {
         if (copy_to_user(buf, old_hdr, SZ_SG_HEADER)) {
             retval = -EFAULT;
             goto free_old_hdr;
         }
         buf += SZ_SG_HEADER;
         if (count > old_hdr->reply_len)
             count = old_hdr->reply_len;
         if (count > SZ_SG_HEADER) {
             if (sg_read_oxfer(srp, buf, count - SZ_SG_HEADER)) {
                 retval = -EFAULT;
                 goto free_old_hdr;
             }
         }
     } else
         count = (old_hdr->result == 0) ? 0 : -EIO;
     sg_finish_rem_req(srp);
     sg_remove_request(sfp, srp);
     retval = count;
 free_old_hdr:
     kfree(old_hdr);
     return retval;
 }
 
 static ssize_t
 sg_new_read(Sg_fd * sfp, char __user *buf, size_t count, Sg_request * srp)
 {
     sg_io_hdr_t *hp = &srp->header;
     int err = 0, err2;
     int len;
 
     if (in_compat_syscall()) {
         if (count < sizeof(struct compat_sg_io_hdr)) {
             err = -EINVAL;
             goto err_out;
         }
     } else if (count < SZ_SG_IO_HDR) {
         err = -EINVAL;
         goto err_out;
     }
     hp->sb_len_wr = 0;
     if ((hp->mx_sb_len > 0) && hp->sbp) {
         if ((CHECK_CONDITION & hp->masked_status) ||
             (srp->sense_b[0] & 0x70) == 0x70) {
             int sb_len = SCSI_SENSE_BUFFERSIZE;
             sb_len = (hp->mx_sb_len > sb_len) ? sb_len : hp->mx_sb_len;
             len = 8 + (int) srp->sense_b[7];    /* Additional sense length field */
             len = (len > sb_len) ? sb_len : len;
             if (copy_to_user(hp->sbp, srp->sense_b, len)) {
                 err = -EFAULT;
                 goto err_out;
             }
             hp->driver_status = DRIVER_SENSE;
             hp->sb_len_wr = len;
         }
     }
     if (hp->masked_status || hp->host_status || hp->driver_status)
         hp->info |= SG_INFO_CHECK;
     err = put_sg_io_hdr(hp, buf);
 err_out:
     err2 = sg_finish_rem_req(srp);
     sg_remove_request(sfp, srp);
     return err ? : err2 ? : count;
 }
 
 static ssize_t
 sg_write(struct file *filp, const char __user *buf, size_t count, loff_t * ppos)
 {
     int mxsize, cmd_size, k;
     int input_size, blocking;
     unsigned char opcode;
     Sg_device *sdp;
     Sg_fd *sfp;
     Sg_request *srp;
     struct sg_header old_hdr;
     sg_io_hdr_t *hp;
     unsigned char cmnd[SG_MAX_CDB_SIZE];
     int retval;
 
     retval = sg_check_file_access(filp, __func__);
     if (retval)
         return retval;
 
     if ((!(sfp = (Sg_fd *) filp->private_data)) || (!(sdp = sfp->parentdp)))
         return -ENXIO;
     SCSI_LOG_TIMEOUT(3, sg_printk(KERN_INFO, sdp,
                       "sg_write: count=%d\n", (int) count));
     if (atomic_read(&sdp->detaching))
         return -ENODEV;
     if (!((filp->f_flags & O_NONBLOCK) ||
           scsi_block_when_processing_errors(sdp->device)))
         return -ENXIO;
 
     if (count < SZ_SG_HEADER)
         return -EIO;
     if (copy_from_user(&old_hdr, buf, SZ_SG_HEADER))
         return -EFAULT;
     blocking = !(filp->f_flags & O_NONBLOCK);
     if (old_hdr.reply_len < 0)
         return sg_new_write(sfp, filp, buf, count,
                     blocking, 0, 0, NULL);
     if (count < (SZ_SG_HEADER + 6))
         return -EIO;    /* The minimum scsi command length is 6 bytes. */
 
     buf += SZ_SG_HEADER;
     if (get_user(opcode, buf))
         return -EFAULT;
 
     if (!(srp = sg_add_request(sfp))) {
         SCSI_LOG_TIMEOUT(1, sg_printk(KERN_INFO, sdp,
                           "sg_write: queue full\n"));
         return -EDOM;
     }
     mutex_lock(&sfp->f_mutex);
     if (sfp->next_cmd_len > 0) {
         cmd_size = sfp->next_cmd_len;
         sfp->next_cmd_len = 0;  /* reset so only this write() effected */
     } else {
         cmd_size = COMMAND_SIZE(opcode);    /* based on SCSI command group */
         if ((opcode >= 0xc0) && old_hdr.twelve_byte)
             cmd_size = 12;
     }
     mutex_unlock(&sfp->f_mutex);
     SCSI_LOG_TIMEOUT(4, sg_printk(KERN_INFO, sdp,
         "sg_write:   scsi opcode=0x%02x, cmd_size=%d\n", (int) opcode, cmd_size));
 /* Determine buffer size.  */
     input_size = count - cmd_size;
     mxsize = (input_size > old_hdr.reply_len) ? input_size : old_hdr.reply_len;
     mxsize -= SZ_SG_HEADER;
     input_size -= SZ_SG_HEADER;
     if (input_size < 0) {
         sg_remove_request(sfp, srp);
         return -EIO;    /* User did not pass enough bytes for this command. */
     }
     hp = &srp->header;
     hp->interface_id = '\0';    /* indicator of old interface tunnelled */
     hp->cmd_len = (unsigned char) cmd_size;
     hp->iovec_count = 0;
     hp->mx_sb_len = 0;
     if (input_size > 0)
         hp->dxfer_direction = (old_hdr.reply_len > SZ_SG_HEADER) ?
             SG_DXFER_TO_FROM_DEV : SG_DXFER_TO_DEV;
     else
         hp->dxfer_direction = (mxsize > 0) ? SG_DXFER_FROM_DEV : SG_DXFER_NONE;
     hp->dxfer_len = mxsize;
     if ((hp->dxfer_direction == SG_DXFER_TO_DEV) ||
         (hp->dxfer_direction == SG_DXFER_TO_FROM_DEV))
         hp->dxferp = (char __user *)buf + cmd_size;
     else
         hp->dxferp = NULL;
     hp->sbp = NULL;
     hp->timeout = old_hdr.reply_len;    /* structure abuse ... */
     hp->flags = input_size; /* structure abuse ... */
     hp->pack_id = old_hdr.pack_id;
     hp->usr_ptr = NULL;
     if (copy_from_user(cmnd, buf, cmd_size)) {
         sg_remove_request(sfp, srp);
         return -EFAULT;
     }
     /*
      * SG_DXFER_TO_FROM_DEV is functionally equivalent to SG_DXFER_FROM_DEV,
      * but is is possible that the app intended SG_DXFER_TO_DEV, because there
      * is a non-zero input_size, so emit a warning.
      */
     if (hp->dxfer_direction == SG_DXFER_TO_FROM_DEV) {
         printk_ratelimited(KERN_WARNING
                    "sg_write: data in/out %d/%d bytes "
                    "for SCSI command 0x%x-- guessing "
                    "data in;\n   program %s not setting "
                    "count and/or reply_len properly\n",
                    old_hdr.reply_len - (int)SZ_SG_HEADER,
                    input_size, (unsigned int) cmnd[0],
                    current->comm);
     }
     k = sg_common_write(sfp, srp, cmnd, sfp->timeout, blocking);
     return (k < 0) ? k : count;
 }
 
 static ssize_t
 sg_new_write(Sg_fd *sfp, struct file *file, const char __user *buf,
          size_t count, int blocking, int read_only, int sg_io_owned,
          Sg_request **o_srp)
 {
     int k;
     Sg_request *srp;
     sg_io_hdr_t *hp;
     unsigned char cmnd[SG_MAX_CDB_SIZE];
     int timeout;
     unsigned long ul_timeout;
 
     if (count < SZ_SG_IO_HDR)
         return -EINVAL;
 
     sfp->cmd_q = 1; /* when sg_io_hdr seen, set command queuing on */
     if (!(srp = sg_add_request(sfp))) {
         SCSI_LOG_TIMEOUT(1, sg_printk(KERN_INFO, sfp->parentdp,
                           "sg_new_write: queue full\n"));
         return -EDOM;
     }
     srp->sg_io_owned = sg_io_owned;
     hp = &srp->header;
     if (get_sg_io_hdr(hp, buf)) {
         sg_remove_request(sfp, srp);
         return -EFAULT;
     }
     if (hp->interface_id != 'S') {
         sg_remove_request(sfp, srp);
         return -ENOSYS;
     }
     if (hp->flags & SG_FLAG_MMAP_IO) {
         if (hp->dxfer_len > sfp->reserve.bufflen) {
             sg_remove_request(sfp, srp);
             return -ENOMEM; /* MMAP_IO size must fit in reserve buffer */
         }
         if (hp->flags & SG_FLAG_DIRECT_IO) {
             sg_remove_request(sfp, srp);
             return -EINVAL; /* either MMAP_IO or DIRECT_IO (not both) */
         }
         if (sfp->res_in_use) {
             sg_remove_request(sfp, srp);
             return -EBUSY;  /* reserve buffer already being used */
         }
     }
     ul_timeout = msecs_to_jiffies(srp->header.timeout);
     timeout = (ul_timeout < INT_MAX) ? ul_timeout : INT_MAX;
     if ((!hp->cmdp) || (hp->cmd_len < 6) || (hp->cmd_len > sizeof (cmnd))) {
         sg_remove_request(sfp, srp);
         return -EMSGSIZE;
     }
     if (copy_from_user(cmnd, hp->cmdp, hp->cmd_len)) {
         sg_remove_request(sfp, srp);
         return -EFAULT;
     }
     if (read_only && sg_allow_access(file, cmnd)) {
         sg_remove_request(sfp, srp);
         return -EPERM;
     }
     k = sg_common_write(sfp, srp, cmnd, timeout, blocking);
     if (k < 0)
         return k;
     if (o_srp)
         *o_srp = srp;
     return count;
 }
 
 static int
 sg_common_write(Sg_fd * sfp, Sg_request * srp,
         unsigned char *cmnd, int timeout, int blocking)
 {
     int k, at_head;
     Sg_device *sdp = sfp->parentdp;
     sg_io_hdr_t *hp = &srp->header;
 
     srp->data.cmd_opcode = cmnd[0]; /* hold opcode of command */
     hp->status = 0;
     hp->masked_status = 0;
     hp->msg_status = 0;
     hp->info = 0;
     hp->host_status = 0;
     hp->driver_status = 0;
     hp->resid = 0;
     SCSI_LOG_TIMEOUT(4, sg_printk(KERN_INFO, sfp->parentdp,
             "sg_common_write:  scsi opcode=0x%02x, cmd_size=%d\n",
             (int) cmnd[0], (int) hp->cmd_len));
 
     if (hp->dxfer_len >= SZ_256M) {
         sg_remove_request(sfp, srp);
         return -EINVAL;
     }
 
     k = sg_start_req(srp, cmnd);
     if (k) {
         SCSI_LOG_TIMEOUT(1, sg_printk(KERN_INFO, sfp->parentdp,
             "sg_common_write: start_req err=%d\n", k));
         sg_finish_rem_req(srp);
         sg_remove_request(sfp, srp);
         return k;   /* probably out of space --> ENOMEM */
     }
     if (atomic_read(&sdp->detaching)) {
         if (srp->bio) {
             blk_mq_free_request(srp->rq);
             srp->rq = NULL;
         }
 
         sg_finish_rem_req(srp);
         sg_remove_request(sfp, srp);
         return -ENODEV;
     }
 
     hp->duration = jiffies_to_msecs(jiffies);
     if (hp->interface_id != '\0' && /* v3 (or later) interface */
         (SG_FLAG_Q_AT_TAIL & hp->flags))
         at_head = 0;
     else
         at_head = 1;
 
     srp->rq->timeout = timeout;
     kref_get(&sfp->f_ref); /* sg_rq_end_io() does kref_put(). */
     srp->rq->end_io = sg_rq_end_io;
     blk_execute_rq_nowait(srp->rq, at_head);
     return 0;
 }
 
 static int srp_done(Sg_fd *sfp, Sg_request *srp)
 {
     unsigned long flags;
     int ret;
 
     read_lock_irqsave(&sfp->rq_list_lock, flags);
     ret = srp->done;
     read_unlock_irqrestore(&sfp->rq_list_lock, flags);
     return ret;
 }
 
 static int max_sectors_bytes(struct request_queue *q)
 {
     unsigned int max_sectors = queue_max_sectors(q);
 
     max_sectors = min_t(unsigned int, max_sectors, INT_MAX >> 9);
 
     return max_sectors << 9;
 }
 
 static void
 sg_fill_request_table(Sg_fd *sfp, sg_req_info_t *rinfo)
 {
     Sg_request *srp;
     int val;
     unsigned int ms;
 
     val = 0;
     list_for_each_entry(srp, &sfp->rq_list, entry) {
         if (val >= SG_MAX_QUEUE)
             break;
         rinfo[val].req_state = srp->done + 1;
         rinfo[val].problem =
             srp->header.masked_status &
             srp->header.host_status &
             srp->header.driver_status;
         if (srp->done)
             rinfo[val].duration =
                 srp->header.duration;
         else {
             ms = jiffies_to_msecs(jiffies);
             rinfo[val].duration =
                 (ms > srp->header.duration) ?
                 (ms - srp->header.duration) : 0;
         }
         rinfo[val].orphan = srp->orphan;
         rinfo[val].sg_io_owned = srp->sg_io_owned;
         rinfo[val].pack_id = srp->header.pack_id;
         rinfo[val].usr_ptr = srp->header.usr_ptr;
         val++;
     }
 }
 
 #ifdef CONFIG_COMPAT
 struct compat_sg_req_info { /* used by SG_GET_REQUEST_TABLE ioctl() */
     char req_state;
     char orphan;
     char sg_io_owned;
     char problem;
     int pack_id;
     compat_uptr_t usr_ptr;
     unsigned int duration;
     int unused;
 };
 
 static int put_compat_request_table(struct compat_sg_req_info __user *o,
                     struct sg_req_info *rinfo)
 {
     int i;
     for (i = 0; i < SG_MAX_QUEUE; i++) {
         if (copy_to_user(o + i, rinfo + i, offsetof(sg_req_info_t, usr_ptr)) ||
             put_user((uintptr_t)rinfo[i].usr_ptr, &o[i].usr_ptr) ||
             put_user(rinfo[i].duration, &o[i].duration) ||
             put_user(rinfo[i].unused, &o[i].unused))
             return -EFAULT;
     }
     return 0;
 }
 #endif
 
 static long
 sg_ioctl_common(struct file *filp, Sg_device *sdp, Sg_fd *sfp,
         unsigned int cmd_in, void __user *p)
 {
     int __user *ip = p;
     int result, val, read_only;
     Sg_request *srp;
     unsigned long iflags;
 
     SCSI_LOG_TIMEOUT(3, sg_printk(KERN_INFO, sdp,
                    "sg_ioctl: cmd=0x%x\n", (int) cmd_in));
     read_only = (O_RDWR != (filp->f_flags & O_ACCMODE));
 
     switch (cmd_in) {
     case SG_IO:
         if (atomic_read(&sdp->detaching))
             return -ENODEV;
         if (!scsi_block_when_processing_errors(sdp->device))
             return -ENXIO;
         result = sg_new_write(sfp, filp, p, SZ_SG_IO_HDR,
                  1, read_only, 1, &srp);
         if (result < 0)
             return result;
         result = wait_event_interruptible(sfp->read_wait,
             srp_done(sfp, srp));
         write_lock_irq(&sfp->rq_list_lock);
         if (srp->done) {
             srp->done = 2;
             write_unlock_irq(&sfp->rq_list_lock);
             result = sg_new_read(sfp, p, SZ_SG_IO_HDR, srp);
             return (result < 0) ? result : 0;
         }
         srp->orphan = 1;
         write_unlock_irq(&sfp->rq_list_lock);
         return result;  /* -ERESTARTSYS because signal hit process */
     case SG_SET_TIMEOUT:
         result = get_user(val, ip);
         if (result)
             return result;
         if (val < 0)
             return -EIO;
         if (val >= mult_frac((s64)INT_MAX, USER_HZ, HZ))
             val = min_t(s64, mult_frac((s64)INT_MAX, USER_HZ, HZ),
                     INT_MAX);
         sfp->timeout_user = val;
         sfp->timeout = mult_frac(val, HZ, USER_HZ);
 
         return 0;
     case SG_GET_TIMEOUT:    /* N.B. User receives timeout as return value */
                 /* strange ..., for backward compatibility */
         return sfp->timeout_user;
     case SG_SET_FORCE_LOW_DMA:
         /*
          * N.B. This ioctl never worked properly, but failed to
          * return an error value. So returning '0' to keep compability
          * with legacy applications.
          */
         return 0;
     case SG_GET_LOW_DMA:
         return put_user(0, ip);
     case SG_GET_SCSI_ID:
         {
             sg_scsi_id_t v;
 
             if (atomic_read(&sdp->detaching))
                 return -ENODEV;
             memset(&v, 0, sizeof(v));
             v.host_no = sdp->device->host->host_no;
             v.channel = sdp->device->channel;
             v.scsi_id = sdp->device->id;
             v.lun = sdp->device->lun;
             v.scsi_type = sdp->device->type;
             v.h_cmd_per_lun = sdp->device->host->cmd_per_lun;
             v.d_queue_depth = sdp->device->queue_depth;
             if (copy_to_user(p, &v, sizeof(sg_scsi_id_t)))
                 return -EFAULT;
             return 0;
         }
     case SG_SET_FORCE_PACK_ID:
         result = get_user(val, ip);
         if (result)
             return result;
         sfp->force_packid = val ? 1 : 0;
         return 0;
     case SG_GET_PACK_ID:
         read_lock_irqsave(&sfp->rq_list_lock, iflags);
         list_for_each_entry(srp, &sfp->rq_list, entry) {
             if ((1 == srp->done) && (!srp->sg_io_owned)) {
                 read_unlock_irqrestore(&sfp->rq_list_lock,
                                iflags);
                 return put_user(srp->header.pack_id, ip);
             }
         }
         read_unlock_irqrestore(&sfp->rq_list_lock, iflags);
         return put_user(-1, ip);
     case SG_GET_NUM_WAITING:
         read_lock_irqsave(&sfp->rq_list_lock, iflags);
         val = 0;
         list_for_each_entry(srp, &sfp->rq_list, entry) {
             if ((1 == srp->done) && (!srp->sg_io_owned))
                 ++val;
         }
         read_unlock_irqrestore(&sfp->rq_list_lock, iflags);
         return put_user(val, ip);
     case SG_GET_SG_TABLESIZE:
         return put_user(sdp->sg_tablesize, ip);
     case SG_SET_RESERVED_SIZE:
         result = get_user(val, ip);
         if (result)
             return result;
                 if (val < 0)
                         return -EINVAL;
         val = min_t(int, val,
                 max_sectors_bytes(sdp->device->request_queue));
         mutex_lock(&sfp->f_mutex);
         if (val != sfp->reserve.bufflen) {
             if (sfp->mmap_called ||
                 sfp->res_in_use) {
                 mutex_unlock(&sfp->f_mutex);
                 return -EBUSY;
             }
 
             sg_remove_scat(sfp, &sfp->reserve);
             sg_build_reserve(sfp, val);
         }
         mutex_unlock(&sfp->f_mutex);
         return 0;
     case SG_GET_RESERVED_SIZE:
         val = min_t(int, sfp->reserve.bufflen,
                 max_sectors_bytes(sdp->device->request_queue));
         return put_user(val, ip);
     case SG_SET_COMMAND_Q:
         result = get_user(val, ip);
         if (result)
             return result;
         sfp->cmd_q = val ? 1 : 0;
         return 0;
     case SG_GET_COMMAND_Q:
         return put_user((int) sfp->cmd_q, ip);
     case SG_SET_KEEP_ORPHAN:
         result = get_user(val, ip);
         if (result)
             return result;
         sfp->keep_orphan = val;
         return 0;
     case SG_GET_KEEP_ORPHAN:
         return put_user((int) sfp->keep_orphan, ip);
     case SG_NEXT_CMD_LEN:
         result = get_user(val, ip);
         if (result)
             return result;
         if (val > SG_MAX_CDB_SIZE)
             return -ENOMEM;
         sfp->next_cmd_len = (val > 0) ? val : 0;
         return 0;
     case SG_GET_VERSION_NUM:
         return put_user(sg_version_num, ip);
     case SG_GET_ACCESS_COUNT:
         /* faked - we don't have a real access count anymore */
         val = (sdp->device ? 1 : 0);
         return put_user(val, ip);
     case SG_GET_REQUEST_TABLE:
         {
             sg_req_info_t *rinfo;
 
             rinfo = kcalloc(SG_MAX_QUEUE, SZ_SG_REQ_INFO,
                     GFP_KERNEL);
             if (!rinfo)
                 return -ENOMEM;
             read_lock_irqsave(&sfp->rq_list_lock, iflags);
             sg_fill_request_table(sfp, rinfo);
             read_unlock_irqrestore(&sfp->rq_list_lock, iflags);
     #ifdef CONFIG_COMPAT
             if (in_compat_syscall())
                 result = put_compat_request_table(p, rinfo);
             else
     #endif
                 result = copy_to_user(p, rinfo,
                               SZ_SG_REQ_INFO * SG_MAX_QUEUE);
             result = result ? -EFAULT : 0;
             kfree(rinfo);
             return result;
         }
     case SG_EMULATED_HOST:
         if (atomic_read(&sdp->detaching))
             return -ENODEV;
         return put_user(sdp->device->host->hostt->emulated, ip);
     case SCSI_IOCTL_SEND_COMMAND:
         if (atomic_read(&sdp->detaching))
             return -ENODEV;
         return scsi_ioctl(sdp->device, filp->f_mode, cmd_in, p);
     case SG_SET_DEBUG:
         result = get_user(val, ip);
         if (result)
             return result;
         sdp->sgdebug = (char) val;
         return 0;
     case BLKSECTGET:
         return put_user(max_sectors_bytes(sdp->device->request_queue),
                 ip);
     case BLKTRACESETUP:
         return blk_trace_setup(sdp->device->request_queue, sdp->name,
                        MKDEV(SCSI_GENERIC_MAJOR, sdp->index),
                        NULL, p);
     case BLKTRACESTART:
         return blk_trace_startstop(sdp->device->request_queue, 1);
     case BLKTRACESTOP:
         return blk_trace_startstop(sdp->device->request_queue, 0);
     case BLKTRACETEARDOWN:
         return blk_trace_remove(sdp->device->request_queue);
     case SCSI_IOCTL_GET_IDLUN:
     case SCSI_IOCTL_GET_BUS_NUMBER:
     case SCSI_IOCTL_PROBE_HOST:
     case SG_GET_TRANSFORM:
     case SG_SCSI_RESET:
         if (atomic_read(&sdp->detaching))
             return -ENODEV;
         break;
     default:
         if (read_only)
             return -EPERM;  /* don't know so take safe approach */
         break;
     }
 
     result = scsi_ioctl_block_when_processing_errors(sdp->device,
             cmd_in, filp->f_flags & O_NDELAY);
     if (result)
         return result;
 
     return -ENOIOCTLCMD;
 }
 
 static long
 sg_ioctl(struct file *filp, unsigned int cmd_in, unsigned long arg)
 {
     void __user *p = (void __user *)arg;
     Sg_device *sdp;
     Sg_fd *sfp;
     int ret;
 
     if ((!(sfp = (Sg_fd *) filp->private_data)) || (!(sdp = sfp->parentdp)))
         return -ENXIO;
 
     ret = sg_ioctl_common(filp, sdp, sfp, cmd_in, p);
     if (ret != -ENOIOCTLCMD)
         return ret;
     return scsi_ioctl(sdp->device, filp->f_mode, cmd_in, p);
 }
 
 static __poll_t
 sg_poll(struct file *filp, poll_table * wait)
 {
     __poll_t res = 0;
     Sg_device *sdp;
     Sg_fd *sfp;
     Sg_request *srp;
     int count = 0;
     unsigned long iflags;
 
     sfp = filp->private_data;
     if (!sfp)
         return EPOLLERR;
     sdp = sfp->parentdp;
     if (!sdp)
         return EPOLLERR;
     poll_wait(filp, &sfp->read_wait, wait);
     read_lock_irqsave(&sfp->rq_list_lock, iflags);
     list_for_each_entry(srp, &sfp->rq_list, entry) {
         /* if any read waiting, flag it */
         if ((0 == res) && (1 == srp->done) && (!srp->sg_io_owned))
             res = EPOLLIN | EPOLLRDNORM;
         ++count;
     }
     read_unlock_irqrestore(&sfp->rq_list_lock, iflags);
 
     if (atomic_read(&sdp->detaching))
         res |= EPOLLHUP;
     else if (!sfp->cmd_q) {
         if (0 == count)
             res |= EPOLLOUT | EPOLLWRNORM;
     } else if (count < SG_MAX_QUEUE)
         res |= EPOLLOUT | EPOLLWRNORM;
     SCSI_LOG_TIMEOUT(3, sg_printk(KERN_INFO, sdp,
                       "sg_poll: res=0x%x\n", (__force u32) res));
     return res;
 }
 
 static int
 sg_fasync(int fd, struct file *filp, int mode)
 {
     Sg_device *sdp;
     Sg_fd *sfp;
 
     if ((!(sfp = (Sg_fd *) filp->private_data)) || (!(sdp = sfp->parentdp)))
         return -ENXIO;
     SCSI_LOG_TIMEOUT(3, sg_printk(KERN_INFO, sdp,
                       "sg_fasync: mode=%d\n", mode));
 
     return fasync_helper(fd, filp, mode, &sfp->async_qp);
 }
 
 static vm_fault_t
 sg_vma_fault(struct vm_fault *vmf)
 {
     struct vm_area_struct *vma = vmf->vma;
     Sg_fd *sfp;
     unsigned long offset, len, sa;
     Sg_scatter_hold *rsv_schp;
     int k, length;
 
     if ((NULL == vma) || (!(sfp = (Sg_fd *) vma->vm_private_data)))
         return VM_FAULT_SIGBUS;
     rsv_schp = &sfp->reserve;
     offset = vmf->pgoff << PAGE_SHIFT;
     if (offset >= rsv_schp->bufflen)
         return VM_FAULT_SIGBUS;
     SCSI_LOG_TIMEOUT(3, sg_printk(KERN_INFO, sfp->parentdp,
                       "sg_vma_fault: offset=%lu, scatg=%d\n",
                       offset, rsv_schp->k_use_sg));
     sa = vma->vm_start;
     length = 1 << (PAGE_SHIFT + rsv_schp->page_order);
     for (k = 0; k < rsv_schp->k_use_sg && sa < vma->vm_end; k++) {
         len = vma->vm_end - sa;
         len = (len < length) ? len : length;
         if (offset < len) {
             struct page *page = nth_page(rsv_schp->pages[k],
                              offset >> PAGE_SHIFT);
             get_page(page); /* increment page count */
             vmf->page = page;
             return 0; /* success */
         }
         sa += len;
         offset -= len;
     }
 
     return VM_FAULT_SIGBUS;
 }
 
 static const struct vm_operations_struct sg_mmap_vm_ops = {
     .fault = sg_vma_fault,
 };
 
 static int
 sg_mmap(struct file *filp, struct vm_area_struct *vma)
 {
     Sg_fd *sfp;
     unsigned long req_sz, len, sa;
     Sg_scatter_hold *rsv_schp;
     int k, length;
     int ret = 0;
 
     if ((!filp) || (!vma) || (!(sfp = (Sg_fd *) filp->private_data)))
         return -ENXIO;
     req_sz = vma->vm_end - vma->vm_start;
     SCSI_LOG_TIMEOUT(3, sg_printk(KERN_INFO, sfp->parentdp,
                       "sg_mmap starting, vm_start=%p, len=%d\n",
                       (void *) vma->vm_start, (int) req_sz));
     if (vma->vm_pgoff)
         return -EINVAL; /* want no offset */
     rsv_schp = &sfp->reserve;
     mutex_lock(&sfp->f_mutex);
     if (req_sz > rsv_schp->bufflen) {
         ret = -ENOMEM;  /* cannot map more than reserved buffer */
         goto out;
     }
 
     sa = vma->vm_start;
     length = 1 << (PAGE_SHIFT + rsv_schp->page_order);
     for (k = 0; k < rsv_schp->k_use_sg && sa < vma->vm_end; k++) {
         len = vma->vm_end - sa;
         len = (len < length) ? len : length;
         sa += len;
     }
 
     sfp->mmap_called = 1;
     vma->vm_flags |= VM_IO | VM_DONTEXPAND | VM_DONTDUMP;
     vma->vm_private_data = sfp;
     vma->vm_ops = &sg_mmap_vm_ops;
 out:
     mutex_unlock(&sfp->f_mutex);
     return ret;
 }
 
 static void
 sg_rq_end_io_usercontext(struct work_struct *work)
 {
     struct sg_request *srp = container_of(work, struct sg_request, ew.work);
     struct sg_fd *sfp = srp->parentfp;
 
     sg_finish_rem_req(srp);
     sg_remove_request(sfp, srp);
     kref_put(&sfp->f_ref, sg_remove_sfp);
 }
 
 /*
  * This function is a "bottom half" handler that is called by the mid
  * level when a command is completed (or has failed).
  */
 static void
 sg_rq_end_io(struct request *rq, blk_status_t status)
 {
     struct scsi_cmnd *scmd = blk_mq_rq_to_pdu(rq);
     struct sg_request *srp = rq->end_io_data;
     Sg_device *sdp;
     Sg_fd *sfp;
     unsigned long iflags;
     unsigned int ms;
     char *sense;
     int result, resid, done = 1;
 
     if (WARN_ON(srp->done != 0))
         return;
 
     sfp = srp->parentfp;
     if (WARN_ON(sfp == NULL))
         return;
 
     sdp = sfp->parentdp;
     if (unlikely(atomic_read(&sdp->detaching)))
         pr_info("%s: device detaching\n", __func__);
 
     sense = scmd->sense_buffer;
     result = scmd->result;
     resid = scmd->resid_len;
 
     SCSI_LOG_TIMEOUT(4, sg_printk(KERN_INFO, sdp,
                       "sg_cmd_done: pack_id=%d, res=0x%x\n",
                       srp->header.pack_id, result));
     srp->header.resid = resid;
     ms = jiffies_to_msecs(jiffies);
     srp->header.duration = (ms > srp->header.duration) ?
                 (ms - srp->header.duration) : 0;
     if (0 != result) {
         struct scsi_sense_hdr sshdr;
 
         srp->header.status = 0xff & result;
         srp->header.masked_status = status_byte(result);
         srp->header.msg_status = COMMAND_COMPLETE;
         srp->header.host_status = host_byte(result);
         srp->header.driver_status = driver_byte(result);
         if ((sdp->sgdebug > 0) &&
             ((CHECK_CONDITION == srp->header.masked_status) ||
              (COMMAND_TERMINATED == srp->header.masked_status)))
             __scsi_print_sense(sdp->device, __func__, sense,
                        SCSI_SENSE_BUFFERSIZE);
 
         /* Following if statement is a patch supplied by Eric Youngdale */
         if (driver_byte(result) != 0
             && scsi_normalize_sense(sense, SCSI_SENSE_BUFFERSIZE, &sshdr)
             && !scsi_sense_is_deferred(&sshdr)
             && sshdr.sense_key == UNIT_ATTENTION
             && sdp->device->removable) {
             /* Detected possible disc change. Set the bit - this */
             /* may be used if there are filesystems using this device */
             sdp->device->changed = 1;
         }
     }
 
     if (scmd->sense_len)
         memcpy(srp->sense_b, scmd->sense_buffer, SCSI_SENSE_BUFFERSIZE);
 
     /* Rely on write phase to clean out srp status values, so no "else" */
 
     /*
      * Free the request as soon as it is complete so that its resources
      * can be reused without waiting for userspace to read() the
      * result.  But keep the associated bio (if any) around until
      * blk_rq_unmap_user() can be called from user context.
      */
     srp->rq = NULL;
     blk_mq_free_request(rq);
 
     write_lock_irqsave(&sfp->rq_list_lock, iflags);
     if (unlikely(srp->orphan)) {
         if (sfp->keep_orphan)
             srp->sg_io_owned = 0;
         else
             done = 0;
     }
     srp->done = done;
     write_unlock_irqrestore(&sfp->rq_list_lock, iflags);
 
     if (likely(done)) {
         /* Now wake up any sg_read() that is waiting for this
          * packet.
          */
         wake_up_interruptible(&sfp->read_wait);
         kill_fasync(&sfp->async_qp, SIGPOLL, POLL_IN);
         kref_put(&sfp->f_ref, sg_remove_sfp);
     } else {
         INIT_WORK(&srp->ew.work, sg_rq_end_io_usercontext);
         schedule_work(&srp->ew.work);
     }
 }
 
 static const struct file_operations sg_fops = {
     .owner = THIS_MODULE,
     .read = sg_read,
     .write = sg_write,
     .poll = sg_poll,
     .unlocked_ioctl = sg_ioctl,
     .compat_ioctl = compat_ptr_ioctl,
     .open = sg_open,
     .mmap = sg_mmap,
     .release = sg_release,
     .fasync = sg_fasync,
     .llseek = no_llseek,
 };
 
 static struct class *sg_sysfs_class;
 
 static int sg_sysfs_valid = 0;
 
 static Sg_device *
 sg_alloc(struct scsi_device *scsidp)
 {
     struct request_queue *q = scsidp->request_queue;
     Sg_device *sdp;
     unsigned long iflags;
     int error;
     u32 k;
 
     sdp = kzalloc(sizeof(Sg_device), GFP_KERNEL);
     if (!sdp) {
         sdev_printk(KERN_WARNING, scsidp, "%s: kmalloc Sg_device "
                 "failure\n", __func__);
         return ERR_PTR(-ENOMEM);
     }
 
     idr_preload(GFP_KERNEL);
     write_lock_irqsave(&sg_index_lock, iflags);
 
     error = idr_alloc(&sg_index_idr, sdp, 0, SG_MAX_DEVS, GFP_NOWAIT);
     if (error < 0) {
         if (error == -ENOSPC) {
             sdev_printk(KERN_WARNING, scsidp,
                     "Unable to attach sg device type=%d, minor number exceeds %d\n",
                     scsidp->type, SG_MAX_DEVS - 1);
             error = -ENODEV;
         } else {
             sdev_printk(KERN_WARNING, scsidp, "%s: idr "
                     "allocation Sg_device failure: %d\n",
                     __func__, error);
         }
         goto out_unlock;
     }
     k = error;
 
     SCSI_LOG_TIMEOUT(3, sdev_printk(KERN_INFO, scsidp,
                     "sg_alloc: dev=%d \n", k));
     sprintf(sdp->name, "sg%d", k);
     sdp->device = scsidp;
     mutex_init(&sdp->open_rel_lock);
     INIT_LIST_HEAD(&sdp->sfds);
     init_waitqueue_head(&sdp->open_wait);
     atomic_set(&sdp->detaching, 0);
     rwlock_init(&sdp->sfd_lock);
     sdp->sg_tablesize = queue_max_segments(q);
     sdp->index = k;
     kref_init(&sdp->d_ref);
     error = 0;
 
 out_unlock:
     write_unlock_irqrestore(&sg_index_lock, iflags);
     idr_preload_end();
 
     if (error) {
         kfree(sdp);
         return ERR_PTR(error);
     }
     return sdp;
 }
 
 static int
 sg_add_device(struct device *cl_dev, struct class_interface *cl_intf)
 {
     struct scsi_device *scsidp = to_scsi_device(cl_dev->parent);
     Sg_device *sdp = NULL;
     struct cdev * cdev = NULL;
     int error;
     unsigned long iflags;
 
     error = -ENOMEM;
     cdev = cdev_alloc();
     if (!cdev) {
         pr_warn("%s: cdev_alloc failed\n", __func__);
         goto out;
     }
     cdev->owner = THIS_MODULE;
     cdev->ops = &sg_fops;
 
     sdp = sg_alloc(scsidp);
     if (IS_ERR(sdp)) {
         pr_warn("%s: sg_alloc failed\n", __func__);
         error = PTR_ERR(sdp);
         goto out;
     }
 
     error = cdev_add(cdev, MKDEV(SCSI_GENERIC_MAJOR, sdp->index), 1);
     if (error)
         goto cdev_add_err;
 
     sdp->cdev = cdev;
     if (sg_sysfs_valid) {
         struct device *sg_class_member;
 
         sg_class_member = device_create(sg_sysfs_class, cl_dev->parent,
                         MKDEV(SCSI_GENERIC_MAJOR,
                               sdp->index),
                         sdp, "%s", sdp->name);
         if (IS_ERR(sg_class_member)) {
             pr_err("%s: device_create failed\n", __func__);
             error = PTR_ERR(sg_class_member);
             goto cdev_add_err;
         }
         error = sysfs_create_link(&scsidp->sdev_gendev.kobj,
                       &sg_class_member->kobj, "generic");
         if (error)
             pr_err("%s: unable to make symlink 'generic' back "
                    "to sg%d\n", __func__, sdp->index);
     } else
         pr_warn("%s: sg_sys Invalid\n", __func__);
 
     sdev_printk(KERN_NOTICE, scsidp, "Attached scsi generic sg%d "
             "type %d\n", sdp->index, scsidp->type);
 
     dev_set_drvdata(cl_dev, sdp);
 
     return 0;
 
 cdev_add_err:
     write_lock_irqsave(&sg_index_lock, iflags);
     idr_remove(&sg_index_idr, sdp->index);
     write_unlock_irqrestore(&sg_index_lock, iflags);
     kfree(sdp);
 
 out:
     if (cdev)
         cdev_del(cdev);
     return error;
 }
 
 static void
 sg_device_destroy(struct kref *kref)
 {
     struct sg_device *sdp = container_of(kref, struct sg_device, d_ref);
     unsigned long flags;
 
     /* CAUTION!  Note that the device can still be found via idr_find()
      * even though the refcount is 0.  Therefore, do idr_remove() BEFORE
      * any other cleanup.
      */
 
     write_lock_irqsave(&sg_index_lock, flags);
     idr_remove(&sg_index_idr, sdp->index);
     write_unlock_irqrestore(&sg_index_lock, flags);
 
     SCSI_LOG_TIMEOUT(3,
         sg_printk(KERN_INFO, sdp, "sg_device_destroy\n"));
 
     kfree(sdp);
 }
 
 static void
 sg_remove_device(struct device *cl_dev, struct class_interface *cl_intf)
 {
     struct scsi_device *scsidp = to_scsi_device(cl_dev->parent);
     Sg_device *sdp = dev_get_drvdata(cl_dev);
     unsigned long iflags;
     Sg_fd *sfp;
     int val;
 
     if (!sdp)
         return;
     /* want sdp->detaching non-zero as soon as possible */
     val = atomic_inc_return(&sdp->detaching);
     if (val > 1)
         return; /* only want to do following once per device */
 
     SCSI_LOG_TIMEOUT(3, sg_printk(KERN_INFO, sdp,
                       "%s\n", __func__));
 
     read_lock_irqsave(&sdp->sfd_lock, iflags);
     list_for_each_entry(sfp, &sdp->sfds, sfd_siblings) {
         wake_up_interruptible_all(&sfp->read_wait);
         kill_fasync(&sfp->async_qp, SIGPOLL, POLL_HUP);
     }
     wake_up_interruptible_all(&sdp->open_wait);
     read_unlock_irqrestore(&sdp->sfd_lock, iflags);
 
     sysfs_remove_link(&scsidp->sdev_gendev.kobj, "generic");
     device_destroy(sg_sysfs_class, MKDEV(SCSI_GENERIC_MAJOR, sdp->index));
     cdev_del(sdp->cdev);
     sdp->cdev = NULL;
 
     kref_put(&sdp->d_ref, sg_device_destroy);
 }
 
 module_param_named(scatter_elem_sz, scatter_elem_sz, int, S_IRUGO | S_IWUSR);
 module_param_named(def_reserved_size, def_reserved_size, int,
            S_IRUGO | S_IWUSR);
 module_param_named(allow_dio, sg_allow_dio, int, S_IRUGO | S_IWUSR);
 
 MODULE_AUTHOR("Douglas Gilbert");
 MODULE_DESCRIPTION("SCSI generic (sg) driver");
 MODULE_LICENSE("GPL");
 MODULE_VERSION(SG_VERSION_STR);
 MODULE_ALIAS_CHARDEV_MAJOR(SCSI_GENERIC_MAJOR);
 
 MODULE_PARM_DESC(scatter_elem_sz, "scatter gather element "
                 "size (default: max(SG_SCATTER_SZ, PAGE_SIZE))");
 MODULE_PARM_DESC(def_reserved_size, "size of buffer reserved for each fd");
 MODULE_PARM_DESC(allow_dio, "allow direct I/O (default: 0 (disallow))");
 
 #ifdef CONFIG_SYSCTL
 #include <linux/sysctl.h>
 
 static struct ctl_table sg_sysctls[] = {
     {
         .procname   = "sg-big-buff",
         .data       = &sg_big_buff,
         .maxlen     = sizeof(int),
         .mode       = 0444,
         .proc_handler   = proc_dointvec,
     },
     {}
 };
 
 static struct ctl_table_header *hdr;
 static void register_sg_sysctls(void)
 {
     if (!hdr)
         hdr = register_sysctl("kernel", sg_sysctls);
 }
 
 static void unregister_sg_sysctls(void)
 {
     if (hdr)
         unregister_sysctl_table(hdr);
 }
 #else
 #define register_sg_sysctls() do { } while (0)
 #define unregister_sg_sysctls() do { } while (0)
 #endif /* CONFIG_SYSCTL */
 
 static int __init
 init_sg(void)
 {
     int rc;
 
     if (scatter_elem_sz < PAGE_SIZE) {
         scatter_elem_sz = PAGE_SIZE;
         scatter_elem_sz_prev = scatter_elem_sz;
     }
     if (def_reserved_size >= 0)
         sg_big_buff = def_reserved_size;
     else
         def_reserved_size = sg_big_buff;
 
     rc = register_chrdev_region(MKDEV(SCSI_GENERIC_MAJOR, 0), 
                     SG_MAX_DEVS, "sg");
     if (rc)
         return rc;
         sg_sysfs_class = class_create(THIS_MODULE, "scsi_generic");
         if ( IS_ERR(sg_sysfs_class) ) {
         rc = PTR_ERR(sg_sysfs_class);
         goto err_out;
         }
     sg_sysfs_valid = 1;
     rc = scsi_register_interface(&sg_interface);
     if (0 == rc) {
 #ifdef CONFIG_SCSI_PROC_FS
         sg_proc_init();
 #endif              /* CONFIG_SCSI_PROC_FS */
         return 0;
     }
     class_destroy(sg_sysfs_class);
     register_sg_sysctls();
 err_out:
     unregister_chrdev_region(MKDEV(SCSI_GENERIC_MAJOR, 0), SG_MAX_DEVS);
     return rc;
 }
 
 static void __exit
 exit_sg(void)
 {
     unregister_sg_sysctls();
 #ifdef CONFIG_SCSI_PROC_FS
     remove_proc_subtree("scsi/sg", NULL);
 #endif              /* CONFIG_SCSI_PROC_FS */
     scsi_unregister_interface(&sg_interface);
     class_destroy(sg_sysfs_class);
     sg_sysfs_valid = 0;
     unregister_chrdev_region(MKDEV(SCSI_GENERIC_MAJOR, 0),
                  SG_MAX_DEVS);
     idr_destroy(&sg_index_idr);
 }
 
 static int
 sg_start_req(Sg_request *srp, unsigned char *cmd)
 {
     int res;
     struct request *rq;
     Sg_fd *sfp = srp->parentfp;
     sg_io_hdr_t *hp = &srp->header;
     int dxfer_len = (int) hp->dxfer_len;
     int dxfer_dir = hp->dxfer_direction;
     unsigned int iov_count = hp->iovec_count;
     Sg_scatter_hold *req_schp = &srp->data;
     Sg_scatter_hold *rsv_schp = &sfp->reserve;
     struct request_queue *q = sfp->parentdp->device->request_queue;
     struct rq_map_data *md, map_data;
     int rw = hp->dxfer_direction == SG_DXFER_TO_DEV ? WRITE : READ;
     struct scsi_cmnd *scmd;
 
     SCSI_LOG_TIMEOUT(4, sg_printk(KERN_INFO, sfp->parentdp,
                       "sg_start_req: dxfer_len=%d\n",
                       dxfer_len));
 
     /*
      * NOTE
      *
      * With scsi-mq enabled, there are a fixed number of preallocated
      * requests equal in number to shost->can_queue.  If all of the
      * preallocated requests are already in use, then scsi_alloc_request()
      * will sleep until an active command completes, freeing up a request.
      * Although waiting in an asynchronous interface is less than ideal, we
      * do not want to use BLK_MQ_REQ_NOWAIT here because userspace might
      * not expect an EWOULDBLOCK from this condition.
      */
     rq = scsi_alloc_request(q, hp->dxfer_direction == SG_DXFER_TO_DEV ?
             REQ_OP_DRV_OUT : REQ_OP_DRV_IN, 0);
     if (IS_ERR(rq))
         return PTR_ERR(rq);
     scmd = blk_mq_rq_to_pdu(rq);
 
     if (hp->cmd_len > sizeof(scmd->cmnd)) {
         blk_mq_free_request(rq);
         return -EINVAL;
     }
 
     memcpy(scmd->cmnd, cmd, hp->cmd_len);
     scmd->cmd_len = hp->cmd_len;
 
     srp->rq = rq;
     rq->end_io_data = srp;
     scmd->allowed = SG_DEFAULT_RETRIES;
 
     if ((dxfer_len <= 0) || (dxfer_dir == SG_DXFER_NONE))
         return 0;
 
     if (sg_allow_dio && hp->flags & SG_FLAG_DIRECT_IO &&
         dxfer_dir != SG_DXFER_UNKNOWN && !iov_count &&
         blk_rq_aligned(q, (unsigned long)hp->dxferp, dxfer_len))
         md = NULL;
     else
         md = &map_data;
 
     if (md) {
         mutex_lock(&sfp->f_mutex);
         if (dxfer_len <= rsv_schp->bufflen &&
             !sfp->res_in_use) {
             sfp->res_in_use = 1;
             sg_link_reserve(sfp, srp, dxfer_len);
         } else if (hp->flags & SG_FLAG_MMAP_IO) {
             res = -EBUSY; /* sfp->res_in_use == 1 */
             if (dxfer_len > rsv_schp->bufflen)
                 res = -ENOMEM;
             mutex_unlock(&sfp->f_mutex);
             return res;
         } else {
             res = sg_build_indirect(req_schp, sfp, dxfer_len);
             if (res) {
                 mutex_unlock(&sfp->f_mutex);
                 return res;
             }
         }
         mutex_unlock(&sfp->f_mutex);
 
         md->pages = req_schp->pages;
         md->page_order = req_schp->page_order;
         md->nr_entries = req_schp->k_use_sg;
         md->offset = 0;
         md->null_mapped = hp->dxferp ? 0 : 1;
         if (dxfer_dir == SG_DXFER_TO_FROM_DEV)
             md->from_user = 1;
         else
             md->from_user = 0;
     }
 
     if (iov_count) {
         struct iovec *iov = NULL;
         struct iov_iter i;
 
         res = import_iovec(rw, hp->dxferp, iov_count, 0, &iov, &i);
         if (res < 0)
             return res;
 
         iov_iter_truncate(&i, hp->dxfer_len);
         if (!iov_iter_count(&i)) {
             kfree(iov);
             return -EINVAL;
         }
 
         res = blk_rq_map_user_iov(q, rq, md, &i, GFP_ATOMIC);
         kfree(iov);
     } else
         res = blk_rq_map_user(q, rq, md, hp->dxferp,
                       hp->dxfer_len, GFP_ATOMIC);
 
     if (!res) {
         srp->bio = rq->bio;
 
         if (!md) {
             req_schp->dio_in_use = 1;
             hp->info |= SG_INFO_DIRECT_IO;
         }
     }
     return res;
 }
 
 static int
 sg_finish_rem_req(Sg_request *srp)
 {
     int ret = 0;
 
     Sg_fd *sfp = srp->parentfp;
     Sg_scatter_hold *req_schp = &srp->data;
 
     SCSI_LOG_TIMEOUT(4, sg_printk(KERN_INFO, sfp->parentdp,
                       "sg_finish_rem_req: res_used=%d\n",
                       (int) srp->res_used));
     if (srp->bio)
         ret = blk_rq_unmap_user(srp->bio);
 
     if (srp->rq)
         blk_mq_free_request(srp->rq);
 
     if (srp->res_used)
         sg_unlink_reserve(sfp, srp);
     else
         sg_remove_scat(sfp, req_schp);
 
     return ret;
 }
 
 static int
 sg_build_sgat(Sg_scatter_hold * schp, const Sg_fd * sfp, int tablesize)
 {
     int sg_bufflen = tablesize * sizeof(struct page *);
     gfp_t gfp_flags = GFP_ATOMIC | __GFP_NOWARN;
 
     schp->pages = kzalloc(sg_bufflen, gfp_flags);
     if (!schp->pages)
         return -ENOMEM;
     schp->sglist_len = sg_bufflen;
     return tablesize;   /* number of scat_gath elements allocated */
 }
 
 static int
 sg_build_indirect(Sg_scatter_hold * schp, Sg_fd * sfp, int buff_size)
 {
     int ret_sz = 0, i, k, rem_sz, num, mx_sc_elems;
     int sg_tablesize = sfp->parentdp->sg_tablesize;
     int blk_size = buff_size, order;
     gfp_t gfp_mask = GFP_ATOMIC | __GFP_COMP | __GFP_NOWARN | __GFP_ZERO;
 
     if (blk_size < 0)
         return -EFAULT;
     if (0 == blk_size)
         ++blk_size; /* don't know why */
     /* round request up to next highest SG_SECTOR_SZ byte boundary */
     blk_size = ALIGN(blk_size, SG_SECTOR_SZ);
     SCSI_LOG_TIMEOUT(4, sg_printk(KERN_INFO, sfp->parentdp,
         "sg_build_indirect: buff_size=%d, blk_size=%d\n",
         buff_size, blk_size));
 
     /* N.B. ret_sz carried into this block ... */
     mx_sc_elems = sg_build_sgat(schp, sfp, sg_tablesize);
     if (mx_sc_elems < 0)
         return mx_sc_elems; /* most likely -ENOMEM */
 
     num = scatter_elem_sz;
     if (unlikely(num != scatter_elem_sz_prev)) {
         if (num < PAGE_SIZE) {
             scatter_elem_sz = PAGE_SIZE;
             scatter_elem_sz_prev = PAGE_SIZE;
         } else
             scatter_elem_sz_prev = num;
     }
 
     order = get_order(num);
 retry:
     ret_sz = 1 << (PAGE_SHIFT + order);
 
     for (k = 0, rem_sz = blk_size; rem_sz > 0 && k < mx_sc_elems;
          k++, rem_sz -= ret_sz) {
 
         num = (rem_sz > scatter_elem_sz_prev) ?
             scatter_elem_sz_prev : rem_sz;
 
         schp->pages[k] = alloc_pages(gfp_mask, order);
         if (!schp->pages[k])
             goto out;
 
         if (num == scatter_elem_sz_prev) {
             if (unlikely(ret_sz > scatter_elem_sz_prev)) {
                 scatter_elem_sz = ret_sz;
                 scatter_elem_sz_prev = ret_sz;
             }
         }
 
         SCSI_LOG_TIMEOUT(5, sg_printk(KERN_INFO, sfp->parentdp,
                  "sg_build_indirect: k=%d, num=%d, ret_sz=%d\n",
                  k, num, ret_sz));
     }       /* end of for loop */
 
     schp->page_order = order;
     schp->k_use_sg = k;
     SCSI_LOG_TIMEOUT(5, sg_printk(KERN_INFO, sfp->parentdp,
              "sg_build_indirect: k_use_sg=%d, rem_sz=%d\n",
              k, rem_sz));
 
     schp->bufflen = blk_size;
     if (rem_sz > 0) /* must have failed */
         return -ENOMEM;
     return 0;
 out:
     for (i = 0; i < k; i++)
         __free_pages(schp->pages[i], order);
 
     if (--order >= 0)
         goto retry;
 
     return -ENOMEM;
 }
 
 static void
 sg_remove_scat(Sg_fd * sfp, Sg_scatter_hold * schp)
 {
     SCSI_LOG_TIMEOUT(4, sg_printk(KERN_INFO, sfp->parentdp,
              "sg_remove_scat: k_use_sg=%d\n", schp->k_use_sg));
     if (schp->pages && schp->sglist_len > 0) {
         if (!schp->dio_in_use) {
             int k;
 
             for (k = 0; k < schp->k_use_sg && schp->pages[k]; k++) {
                 SCSI_LOG_TIMEOUT(5,
                     sg_printk(KERN_INFO, sfp->parentdp,
                     "sg_remove_scat: k=%d, pg=0x%p\n",
                     k, schp->pages[k]));
                 __free_pages(schp->pages[k], schp->page_order);
             }
 
             kfree(schp->pages);
         }
     }
     memset(schp, 0, sizeof (*schp));
 }
 
 static int
 sg_read_oxfer(Sg_request * srp, char __user *outp, int num_read_xfer)
 {
     Sg_scatter_hold *schp = &srp->data;
     int k, num;
 
     SCSI_LOG_TIMEOUT(4, sg_printk(KERN_INFO, srp->parentfp->parentdp,
              "sg_read_oxfer: num_read_xfer=%d\n",
              num_read_xfer));
     if ((!outp) || (num_read_xfer <= 0))
         return 0;
 
     num = 1 << (PAGE_SHIFT + schp->page_order);
     for (k = 0; k < schp->k_use_sg && schp->pages[k]; k++) {
         if (num > num_read_xfer) {
             if (copy_to_user(outp, page_address(schp->pages[k]),
                        num_read_xfer))
                 return -EFAULT;
             break;
         } else {
             if (copy_to_user(outp, page_address(schp->pages[k]),
                        num))
                 return -EFAULT;
             num_read_xfer -= num;
             if (num_read_xfer <= 0)
                 break;
             outp += num;
         }
     }
 
     return 0;
 }
 
 static void
 sg_build_reserve(Sg_fd * sfp, int req_size)
 {
     Sg_scatter_hold *schp = &sfp->reserve;
 
     SCSI_LOG_TIMEOUT(4, sg_printk(KERN_INFO, sfp->parentdp,
              "sg_build_reserve: req_size=%d\n", req_size));
     do {
         if (req_size < PAGE_SIZE)
             req_size = PAGE_SIZE;
         if (0 == sg_build_indirect(schp, sfp, req_size))
             return;
         else
             sg_remove_scat(sfp, schp);
         req_size >>= 1; /* divide by 2 */
     } while (req_size > (PAGE_SIZE / 2));
 }
 
 static void
 sg_link_reserve(Sg_fd * sfp, Sg_request * srp, int size)
 {
     Sg_scatter_hold *req_schp = &srp->data;
     Sg_scatter_hold *rsv_schp = &sfp->reserve;
     int k, num, rem;
 
     srp->res_used = 1;
     SCSI_LOG_TIMEOUT(4, sg_printk(KERN_INFO, sfp->parentdp,
              "sg_link_reserve: size=%d\n", size));
     rem = size;
 
     num = 1 << (PAGE_SHIFT + rsv_schp->page_order);
     for (k = 0; k < rsv_schp->k_use_sg; k++) {
         if (rem <= num) {
             req_schp->k_use_sg = k + 1;
             req_schp->sglist_len = rsv_schp->sglist_len;
             req_schp->pages = rsv_schp->pages;
 
             req_schp->bufflen = size;
             req_schp->page_order = rsv_schp->page_order;
             break;
         } else
             rem -= num;
     }
 
     if (k >= rsv_schp->k_use_sg)
         SCSI_LOG_TIMEOUT(1, sg_printk(KERN_INFO, sfp->parentdp,
                  "sg_link_reserve: BAD size\n"));
 }
 
 static void
 sg_unlink_reserve(Sg_fd * sfp, Sg_request * srp)
 {
     Sg_scatter_hold *req_schp = &srp->data;
 
     SCSI_LOG_TIMEOUT(4, sg_printk(KERN_INFO, srp->parentfp->parentdp,
                       "sg_unlink_reserve: req->k_use_sg=%d\n",
                       (int) req_schp->k_use_sg));
     req_schp->k_use_sg = 0;
     req_schp->bufflen = 0;
     req_schp->pages = NULL;
     req_schp->page_order = 0;
     req_schp->sglist_len = 0;
     srp->res_used = 0;
     /* Called without mutex lock to avoid deadlock */
     sfp->res_in_use = 0;
 }
 
 static Sg_request *
 sg_get_rq_mark(Sg_fd * sfp, int pack_id, bool *busy)
 {
     Sg_request *resp;
     unsigned long iflags;
 
     *busy = false;
     write_lock_irqsave(&sfp->rq_list_lock, iflags);
     list_for_each_entry(resp, &sfp->rq_list, entry) {
         /* look for requests that are not SG_IO owned */
         if ((!resp->sg_io_owned) &&
             ((-1 == pack_id) || (resp->header.pack_id == pack_id))) {
             switch (resp->done) {
             case 0: /* request active */
                 *busy = true;
                 break;
             case 1: /* request done; response ready to return */
                 resp->done = 2; /* guard against other readers */
                 write_unlock_irqrestore(&sfp->rq_list_lock, iflags);
                 return resp;
             case 2: /* response already being returned */
                 break;
             }
         }
     }
     write_unlock_irqrestore(&sfp->rq_list_lock, iflags);
     return NULL;
 }
 
 /* always adds to end of list */
 static Sg_request *
 sg_add_request(Sg_fd * sfp)
 {
     int k;
     unsigned long iflags;
     Sg_request *rp = sfp->req_arr;
 
     write_lock_irqsave(&sfp->rq_list_lock, iflags);
     if (!list_empty(&sfp->rq_list)) {
         if (!sfp->cmd_q)
             goto out_unlock;
 
         for (k = 0; k < SG_MAX_QUEUE; ++k, ++rp) {
             if (!rp->parentfp)
                 break;
         }
         if (k >= SG_MAX_QUEUE)
             goto out_unlock;
     }
     memset(rp, 0, sizeof (Sg_request));
     rp->parentfp = sfp;
     rp->header.duration = jiffies_to_msecs(jiffies);
     list_add_tail(&rp->entry, &sfp->rq_list);
     write_unlock_irqrestore(&sfp->rq_list_lock, iflags);
     return rp;
 out_unlock:
     write_unlock_irqrestore(&sfp->rq_list_lock, iflags);
     return NULL;
 }
 
 /* Return of 1 for found; 0 for not found */
 static int
 sg_remove_request(Sg_fd * sfp, Sg_request * srp)
 {
     unsigned long iflags;
     int res = 0;
 
     if (!sfp || !srp || list_empty(&sfp->rq_list))
         return res;
     write_lock_irqsave(&sfp->rq_list_lock, iflags);
     if (!list_empty(&srp->entry)) {
         list_del(&srp->entry);
         srp->parentfp = NULL;
         res = 1;
     }
     write_unlock_irqrestore(&sfp->rq_list_lock, iflags);
 
     /*
      * If the device is detaching, wakeup any readers in case we just
      * removed the last response, which would leave nothing for them to
      * return other than -ENODEV.
      */
     if (unlikely(atomic_read(&sfp->parentdp->detaching)))
         wake_up_interruptible_all(&sfp->read_wait);
 
     return res;
 }
 
 static Sg_fd *
 sg_add_sfp(Sg_device * sdp)
 {
     Sg_fd *sfp;
     unsigned long iflags;
     int bufflen;
 
     sfp = kzalloc(sizeof(*sfp), GFP_ATOMIC | __GFP_NOWARN);
     if (!sfp)
         return ERR_PTR(-ENOMEM);
 
     init_waitqueue_head(&sfp->read_wait);
     rwlock_init(&sfp->rq_list_lock);
     INIT_LIST_HEAD(&sfp->rq_list);
     kref_init(&sfp->f_ref);
     mutex_init(&sfp->f_mutex);
     sfp->timeout = SG_DEFAULT_TIMEOUT;
     sfp->timeout_user = SG_DEFAULT_TIMEOUT_USER;
     sfp->force_packid = SG_DEF_FORCE_PACK_ID;
     sfp->cmd_q = SG_DEF_COMMAND_Q;
     sfp->keep_orphan = SG_DEF_KEEP_ORPHAN;
     sfp->parentdp = sdp;
     write_lock_irqsave(&sdp->sfd_lock, iflags);
     if (atomic_read(&sdp->detaching)) {
         write_unlock_irqrestore(&sdp->sfd_lock, iflags);
         kfree(sfp);
         return ERR_PTR(-ENODEV);
     }
     list_add_tail(&sfp->sfd_siblings, &sdp->sfds);
     write_unlock_irqrestore(&sdp->sfd_lock, iflags);
     SCSI_LOG_TIMEOUT(3, sg_printk(KERN_INFO, sdp,
                       "sg_add_sfp: sfp=0x%p\n", sfp));
     if (unlikely(sg_big_buff != def_reserved_size))
         sg_big_buff = def_reserved_size;
 
     bufflen = min_t(int, sg_big_buff,
             max_sectors_bytes(sdp->device->request_queue));
     sg_build_reserve(sfp, bufflen);
     SCSI_LOG_TIMEOUT(3, sg_printk(KERN_INFO, sdp,
                       "sg_add_sfp: bufflen=%d, k_use_sg=%d\n",
                       sfp->reserve.bufflen,
                       sfp->reserve.k_use_sg));
 
     kref_get(&sdp->d_ref);
     __module_get(THIS_MODULE);
     return sfp;
 }
 
 static void
 sg_remove_sfp_usercontext(struct work_struct *work)
 {
     struct sg_fd *sfp = container_of(work, struct sg_fd, ew.work);
     struct sg_device *sdp = sfp->parentdp;
     Sg_request *srp;
     unsigned long iflags;
 
     /* Cleanup any responses which were never read(). */
     write_lock_irqsave(&sfp->rq_list_lock, iflags);
     while (!list_empty(&sfp->rq_list)) {
         srp = list_first_entry(&sfp->rq_list, Sg_request, entry);
         sg_finish_rem_req(srp);
         list_del(&srp->entry);
         srp->parentfp = NULL;
     }
     write_unlock_irqrestore(&sfp->rq_list_lock, iflags);
 
     if (sfp->reserve.bufflen > 0) {
         SCSI_LOG_TIMEOUT(6, sg_printk(KERN_INFO, sdp,
                 "sg_remove_sfp:    bufflen=%d, k_use_sg=%d\n",
                 (int) sfp->reserve.bufflen,
                 (int) sfp->reserve.k_use_sg));
         sg_remove_scat(sfp, &sfp->reserve);
     }
 
     SCSI_LOG_TIMEOUT(6, sg_printk(KERN_INFO, sdp,
             "sg_remove_sfp: sfp=0x%p\n", sfp));
     kfree(sfp);
 
     scsi_device_put(sdp->device);
     kref_put(&sdp->d_ref, sg_device_destroy);
     module_put(THIS_MODULE);
 }
 
 static void
 sg_remove_sfp(struct kref *kref)
 {
     struct sg_fd *sfp = container_of(kref, struct sg_fd, f_ref);
     struct sg_device *sdp = sfp->parentdp;
     unsigned long iflags;
 
     write_lock_irqsave(&sdp->sfd_lock, iflags);
     list_del(&sfp->sfd_siblings);
     write_unlock_irqrestore(&sdp->sfd_lock, iflags);
 
     INIT_WORK(&sfp->ew.work, sg_remove_sfp_usercontext);
     schedule_work(&sfp->ew.work);
 }
 
 #ifdef CONFIG_SCSI_PROC_FS
 static int
 sg_idr_max_id(int id, void *p, void *data)
 {
     int *k = data;
 
     if (*k < id)
         *k = id;
 
     return 0;
 }
 
 static int
 sg_last_dev(void)
 {
     int k = -1;
     unsigned long iflags;
 
     read_lock_irqsave(&sg_index_lock, iflags);
     idr_for_each(&sg_index_idr, sg_idr_max_id, &k);
     read_unlock_irqrestore(&sg_index_lock, iflags);
     return k + 1;       /* origin 1 */
 }
 #endif
 
 /* must be called with sg_index_lock held */
 static Sg_device *sg_lookup_dev(int dev)
 {
     return idr_find(&sg_index_idr, dev);
 }
 
 static Sg_device *
 sg_get_dev(int dev)
 {
     struct sg_device *sdp;
     unsigned long flags;
 
     read_lock_irqsave(&sg_index_lock, flags);
     sdp = sg_lookup_dev(dev);
     if (!sdp)
         sdp = ERR_PTR(-ENXIO);
     else if (atomic_read(&sdp->detaching)) {
         /* If sdp->detaching, then the refcount may already be 0, in
          * which case it would be a bug to do kref_get().
          */
         sdp = ERR_PTR(-ENODEV);
     } else
         kref_get(&sdp->d_ref);
     read_unlock_irqrestore(&sg_index_lock, flags);
 
     return sdp;
 }
 
 #ifdef CONFIG_SCSI_PROC_FS
 static int sg_proc_seq_show_int(struct seq_file *s, void *v);
 
 static int sg_proc_single_open_adio(struct inode *inode, struct file *file);
 static ssize_t sg_proc_write_adio(struct file *filp, const char __user *buffer,
                       size_t count, loff_t *off);
 static const struct proc_ops adio_proc_ops = {
     .proc_open  = sg_proc_single_open_adio,
     .proc_read  = seq_read,
     .proc_lseek = seq_lseek,
     .proc_write = sg_proc_write_adio,
     .proc_release   = single_release,
 };
 
 static int sg_proc_single_open_dressz(struct inode *inode, struct file *file);
 static ssize_t sg_proc_write_dressz(struct file *filp, 
         const char __user *buffer, size_t count, loff_t *off);
 static const struct proc_ops dressz_proc_ops = {
     .proc_open  = sg_proc_single_open_dressz,
     .proc_read  = seq_read,
     .proc_lseek = seq_lseek,
     .proc_write = sg_proc_write_dressz,
     .proc_release   = single_release,
 };
 
 static int sg_proc_seq_show_version(struct seq_file *s, void *v);
 static int sg_proc_seq_show_devhdr(struct seq_file *s, void *v);
 static int sg_proc_seq_show_dev(struct seq_file *s, void *v);
 static void * dev_seq_start(struct seq_file *s, loff_t *pos);
 static void * dev_seq_next(struct seq_file *s, void *v, loff_t *pos);
 static void dev_seq_stop(struct seq_file *s, void *v);
 static const struct seq_operations dev_seq_ops = {
     .start = dev_seq_start,
     .next  = dev_seq_next,
     .stop  = dev_seq_stop,
     .show  = sg_proc_seq_show_dev,
 };
 
 static int sg_proc_seq_show_devstrs(struct seq_file *s, void *v);
 static const struct seq_operations devstrs_seq_ops = {
     .start = dev_seq_start,
     .next  = dev_seq_next,
     .stop  = dev_seq_stop,
     .show  = sg_proc_seq_show_devstrs,
 };
 
 static int sg_proc_seq_show_debug(struct seq_file *s, void *v);
 static const struct seq_operations debug_seq_ops = {
     .start = dev_seq_start,
     .next  = dev_seq_next,
     .stop  = dev_seq_stop,
     .show  = sg_proc_seq_show_debug,
 };
 
 static int
 sg_proc_init(void)
 {
     struct proc_dir_entry *p;
 
     p = proc_mkdir("scsi/sg", NULL);
     if (!p)
         return 1;
 
     proc_create("allow_dio", S_IRUGO | S_IWUSR, p, &adio_proc_ops);
     proc_create_seq("debug", S_IRUGO, p, &debug_seq_ops);
     proc_create("def_reserved_size", S_IRUGO | S_IWUSR, p, &dressz_proc_ops);
     proc_create_single("device_hdr", S_IRUGO, p, sg_proc_seq_show_devhdr);
     proc_create_seq("devices", S_IRUGO, p, &dev_seq_ops);
     proc_create_seq("device_strs", S_IRUGO, p, &devstrs_seq_ops);
     proc_create_single("version", S_IRUGO, p, sg_proc_seq_show_version);
     return 0;
 }
 
 
 static int sg_proc_seq_show_int(struct seq_file *s, void *v)
 {
     seq_printf(s, "%d\n", *((int *)s->private));
     return 0;
 }
 
 static int sg_proc_single_open_adio(struct inode *inode, struct file *file)
 {
     return single_open(file, sg_proc_seq_show_int, &sg_allow_dio);
 }
 
 static ssize_t 
 sg_proc_write_adio(struct file *filp, const char __user *buffer,
            size_t count, loff_t *off)
 {
     int err;
     unsigned long num;
 
     if (!capable(CAP_SYS_ADMIN) || !capable(CAP_SYS_RAWIO))
         return -EACCES;
     err = kstrtoul_from_user(buffer, count, 0, &num);
     if (err)
         return err;
     sg_allow_dio = num ? 1 : 0;
     return count;
 }
 
 static int sg_proc_single_open_dressz(struct inode *inode, struct file *file)
 {
     return single_open(file, sg_proc_seq_show_int, &sg_big_buff);
 }
 
 static ssize_t 
 sg_proc_write_dressz(struct file *filp, const char __user *buffer,
              size_t count, loff_t *off)
 {
     int err;
     unsigned long k = ULONG_MAX;
 
     if (!capable(CAP_SYS_ADMIN) || !capable(CAP_SYS_RAWIO))
         return -EACCES;
 
     err = kstrtoul_from_user(buffer, count, 0, &k);
     if (err)
         return err;
     if (k <= 1048576) { /* limit "big buff" to 1 MB */
         sg_big_buff = k;
         return count;
     }
     return -ERANGE;
 }
 
 static int sg_proc_seq_show_version(struct seq_file *s, void *v)
 {
     seq_printf(s, "%d\t%s [%s]\n", sg_version_num, SG_VERSION_STR,
            sg_version_date);
     return 0;
 }
 
 static int sg_proc_seq_show_devhdr(struct seq_file *s, void *v)
 {
     seq_puts(s, "host\tchan\tid\tlun\ttype\topens\tqdepth\tbusy\tonline\n");
     return 0;
 }
 
 struct sg_proc_deviter {
     loff_t  index;
     size_t  max;
 };
 
 static void * dev_seq_start(struct seq_file *s, loff_t *pos)
 {
     struct sg_proc_deviter * it = kmalloc(sizeof(*it), GFP_KERNEL);
 
     s->private = it;
     if (! it)
         return NULL;
 
     it->index = *pos;
     it->max = sg_last_dev();
     if (it->index >= it->max)
         return NULL;
     return it;
 }
 
 static void * dev_seq_next(struct seq_file *s, void *v, loff_t *pos)
 {
     struct sg_proc_deviter * it = s->private;
 
     *pos = ++it->index;
     return (it->index < it->max) ? it : NULL;
 }
 
 static void dev_seq_stop(struct seq_file *s, void *v)
 {
     kfree(s->private);
 }
 
 static int sg_proc_seq_show_dev(struct seq_file *s, void *v)
 {
     struct sg_proc_deviter * it = (struct sg_proc_deviter *) v;
     Sg_device *sdp;
     struct scsi_device *scsidp;
     unsigned long iflags;
 
     read_lock_irqsave(&sg_index_lock, iflags);
     sdp = it ? sg_lookup_dev(it->index) : NULL;
     if ((NULL == sdp) || (NULL == sdp->device) ||
         (atomic_read(&sdp->detaching)))
         seq_puts(s, "-1\t-1\t-1\t-1\t-1\t-1\t-1\t-1\t-1\n");
     else {
         scsidp = sdp->device;
         seq_printf(s, "%d\t%d\t%d\t%llu\t%d\t%d\t%d\t%d\t%d\n",
                   scsidp->host->host_no, scsidp->channel,
                   scsidp->id, scsidp->lun, (int) scsidp->type,
                   1,
                   (int) scsidp->queue_depth,
                   (int) scsi_device_busy(scsidp),
                   (int) scsi_device_online(scsidp));
     }
     read_unlock_irqrestore(&sg_index_lock, iflags);
     return 0;
 }
 
 static int sg_proc_seq_show_devstrs(struct seq_file *s, void *v)
 {
     struct sg_proc_deviter * it = (struct sg_proc_deviter *) v;
     Sg_device *sdp;
     struct scsi_device *scsidp;
     unsigned long iflags;
 
     read_lock_irqsave(&sg_index_lock, iflags);
     sdp = it ? sg_lookup_dev(it->index) : NULL;
     scsidp = sdp ? sdp->device : NULL;
     if (sdp && scsidp && (!atomic_read(&sdp->detaching)))
         seq_printf(s, "%8.8s\t%16.16s\t%4.4s\n",
                scsidp->vendor, scsidp->model, scsidp->rev);
     else
         seq_puts(s, "<no active device>\n");
     read_unlock_irqrestore(&sg_index_lock, iflags);
     return 0;
 }
 
 /* must be called while holding sg_index_lock */
 static void sg_proc_debug_helper(struct seq_file *s, Sg_device * sdp)
 {
     int k, new_interface, blen, usg;
     Sg_request *srp;
     Sg_fd *fp;
     const sg_io_hdr_t *hp;
     const char * cp;
     unsigned int ms;
 
     k = 0;
     list_for_each_entry(fp, &sdp->sfds, sfd_siblings) {
         k++;
         read_lock(&fp->rq_list_lock); /* irqs already disabled */
         seq_printf(s, "   FD(%d): timeout=%dms bufflen=%d "
                "(res)sgat=%d low_dma=%d\n", k,
                jiffies_to_msecs(fp->timeout),
                fp->reserve.bufflen,
                (int) fp->reserve.k_use_sg, 0);
         seq_printf(s, "   cmd_q=%d f_packid=%d k_orphan=%d closed=0\n",
                (int) fp->cmd_q, (int) fp->force_packid,
                (int) fp->keep_orphan);
         list_for_each_entry(srp, &fp->rq_list, entry) {
             hp = &srp->header;
             new_interface = (hp->interface_id == '\0') ? 0 : 1;
             if (srp->res_used) {
                 if (new_interface &&
                     (SG_FLAG_MMAP_IO & hp->flags))
                     cp = "     mmap>> ";
                 else
                     cp = "     rb>> ";
             } else {
                 if (SG_INFO_DIRECT_IO_MASK & hp->info)
                     cp = "     dio>> ";
                 else
                     cp = "     ";
             }
             seq_puts(s, cp);
             blen = srp->data.bufflen;
             usg = srp->data.k_use_sg;
             seq_puts(s, srp->done ?
                  ((1 == srp->done) ?  "rcv:" : "fin:")
                   : "act:");
             seq_printf(s, " id=%d blen=%d",
                    srp->header.pack_id, blen);
             if (srp->done)
                 seq_printf(s, " dur=%d", hp->duration);
             else {
                 ms = jiffies_to_msecs(jiffies);
                 seq_printf(s, " t_o/elap=%d/%d",
                     (new_interface ? hp->timeout :
                           jiffies_to_msecs(fp->timeout)),
                     (ms > hp->duration ? ms - hp->duration : 0));
             }
             seq_printf(s, "ms sgat=%d op=0x%02x\n", usg,
                    (int) srp->data.cmd_opcode);
         }
         if (list_empty(&fp->rq_list))
             seq_puts(s, "     No requests active\n");
         read_unlock(&fp->rq_list_lock);
     }
 }
 
 static int sg_proc_seq_show_debug(struct seq_file *s, void *v)
 {
     struct sg_proc_deviter * it = (struct sg_proc_deviter *) v;
     Sg_device *sdp;
     unsigned long iflags;
 
     if (it && (0 == it->index))
         seq_printf(s, "max_active_device=%d  def_reserved_size=%d\n",
                (int)it->max, sg_big_buff);
 
     read_lock_irqsave(&sg_index_lock, iflags);
     sdp = it ? sg_lookup_dev(it->index) : NULL;
     if (NULL == sdp)
         goto skip;
     read_lock(&sdp->sfd_lock);
     if (!list_empty(&sdp->sfds)) {
         seq_printf(s, " >>> device=%s ", sdp->name);
         if (atomic_read(&sdp->detaching))
             seq_puts(s, "detaching pending close ");
         else if (sdp->device) {
             struct scsi_device *scsidp = sdp->device;
 
             seq_printf(s, "%d:%d:%d:%llu   em=%d",
                    scsidp->host->host_no,
                    scsidp->channel, scsidp->id,
                    scsidp->lun,
                    scsidp->host->hostt->emulated);
         }
         seq_printf(s, " sg_tablesize=%d excl=%d open_cnt=%d\n",
                sdp->sg_tablesize, sdp->exclude, sdp->open_cnt);
         sg_proc_debug_helper(s, sdp);
     }
     read_unlock(&sdp->sfd_lock);
 skip:
     read_unlock_irqrestore(&sg_index_lock, iflags);
     return 0;
 }
 
 #endif              /* CONFIG_SCSI_PROC_FS */
 
 module_init(init_sg);
 module_exit(exit_sg);