Add the rt linux 4.1.3-rt3 as base
[kvmfornfv.git] / kernel / drivers / scsi / sg.c
diff --git a/kernel/drivers/scsi/sg.c b/kernel/drivers/scsi/sg.c
new file mode 100644 (file)
index 0000000..9d7b7db
--- /dev/null
@@ -0,0 +1,2699 @@
+/*
+ *  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
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2, or (at your option)
+ * any later version.
+ *
+ */
+
+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/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 "scsi.h"
+#include <scsi/scsi_dbg.h>
+#include <scsi/scsi_host.h>
+#include <scsi/scsi_driver.h>
+#include <scsi/scsi_ioctl.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);
+static void sg_proc_cleanup(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
+
+/*
+ * Suppose you want to calculate the formula muldiv(x,m,d)=int(x * m / d)
+ * Then when using 32 bit integers x * m may overflow during the calculation.
+ * Replacing muldiv(x) by muldiv(x)=((x % d) * m) / d + int(x / d) * m
+ * calculates the same, but prevents the overflow when both m and d
+ * are "small" numbers (like HZ and USER_HZ).
+ * Of course an overflow is inavoidable if the result of muldiv doesn't fit
+ * in 32 bits.
+ */
+#define MULDIV(X,MUL,DIV) ((((X % DIV) * MUL) / DIV) + ((X / DIV) * MUL))
+
+#define SG_DEFAULT_TIMEOUT MULDIV(SG_DEFAULT_TIMEOUT_USER, HZ, USER_HZ)
+
+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 sg_request *nextrp;      /* NULL -> tail request (slist) */
+       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 */
+       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 */
+       unsigned save_scat_len; /* original length of trunc. scat. element */
+       Sg_request *headrp;     /* head of request slist, NULL->empty */
+       struct fasync_struct *async_qp; /* used by asynchronous notification */
+       Sg_request req_arr[SG_MAX_QUEUE];       /* used as singly-linked list */
+       char low_dma;           /* as in parent but possibly overridden to 1 */
+       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 */
+       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 */
+       struct gendisk *disk;
+       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, int uptodate);
+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);
+static Sg_request *sg_add_request(Sg_fd * sfp);
+static int sg_remove_request(Sg_fd * sfp, Sg_request * srp);
+static int sg_res_in_use(Sg_fd * sfp);
+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)->disk->disk_name, fmt, ##a)
+
+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;
+
+       return blk_verify_command(cmd, filp->f_mode & FMODE_WRITE);
+}
+
+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 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;
+       sg_io_hdr_t *hp;
+       struct sg_header *old_hdr = NULL;
+       int retval = 0;
+
+       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 (!access_ok(VERIFY_WRITE, buf, count))
+               return -EFAULT;
+       if (sfp->force_packid && (count >= SZ_SG_HEADER)) {
+               old_hdr = kmalloc(SZ_SG_HEADER, GFP_KERNEL);
+               if (!old_hdr)
+                       return -ENOMEM;
+               if (__copy_from_user(old_hdr, buf, SZ_SG_HEADER)) {
+                       retval = -EFAULT;
+                       goto free_old_hdr;
+               }
+               if (old_hdr->reply_len < 0) {
+                       if (count >= SZ_SG_IO_HDR) {
+                               sg_io_hdr_t *new_hdr;
+                               new_hdr = kmalloc(SZ_SG_IO_HDR, GFP_KERNEL);
+                               if (!new_hdr) {
+                                       retval = -ENOMEM;
+                                       goto free_old_hdr;
+                               }
+                               retval =__copy_from_user
+                                   (new_hdr, buf, SZ_SG_IO_HDR);
+                               req_pack_id = new_hdr->pack_id;
+                               kfree(new_hdr);
+                               if (retval) {
+                                       retval = -EFAULT;
+                                       goto free_old_hdr;
+                               }
+                       }
+               } else
+                       req_pack_id = old_hdr->pack_id;
+       }
+       srp = sg_get_rq_mark(sfp, req_pack_id);
+       if (!srp) {             /* now wait on packet to arrive */
+               if (atomic_read(&sdp->detaching)) {
+                       retval = -ENODEV;
+                       goto free_old_hdr;
+               }
+               if (filp->f_flags & O_NONBLOCK) {
+                       retval = -EAGAIN;
+                       goto free_old_hdr;
+               }
+               retval = wait_event_interruptible(sfp->read_wait,
+                       (atomic_read(&sdp->detaching) ||
+                       (srp = sg_get_rq_mark(sfp, req_pack_id))));
+               if (atomic_read(&sdp->detaching)) {
+                       retval = -ENODEV;
+                       goto free_old_hdr;
+               }
+               if (retval) {
+                       /* -ERESTARTSYS as signal hit process */
+                       goto free_old_hdr;
+               }
+       }
+       if (srp->header.interface_id != '\0') {
+               retval = sg_new_read(sfp, buf, count, srp);
+               goto free_old_hdr;
+       }
+
+       hp = &srp->header;
+       if (old_hdr == NULL) {
+               old_hdr = kmalloc(SZ_SG_HEADER, GFP_KERNEL);
+               if (! old_hdr) {
+                       retval = -ENOMEM;
+                       goto free_old_hdr;
+               }
+       }
+       memset(old_hdr, 0, SZ_SG_HEADER);
+       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) ||
+           (DRIVER_SENSE & hp->driver_status))
+               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);
+       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 (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) ||
+                   (DRIVER_SENSE & hp->driver_status)) {
+                       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->sb_len_wr = len;
+               }
+       }
+       if (hp->masked_status || hp->host_status || hp->driver_status)
+               hp->info |= SG_INFO_CHECK;
+       if (copy_to_user(buf, hp, SZ_SG_IO_HDR)) {
+               err = -EFAULT;
+               goto err_out;
+       }
+err_out:
+       err2 = sg_finish_rem_req(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];
+
+       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 (!access_ok(VERIFY_READ, buf, count))
+               return -EFAULT; /* protects following copy_from_user()s + get_user()s */
+       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. */
+
+       if (!(srp = sg_add_request(sfp))) {
+               SCSI_LOG_TIMEOUT(1, sg_printk(KERN_INFO, sdp,
+                                             "sg_write: queue full\n"));
+               return -EDOM;
+       }
+       buf += SZ_SG_HEADER;
+       __get_user(opcode, buf);
+       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;
+       }
+       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->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))
+               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) {
+               static char cmd[TASK_COMM_LEN];
+               if (strcmp(current->comm, cmd)) {
+                       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);
+                       strcpy(cmd, 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;
+       if (!access_ok(VERIFY_READ, buf, count))
+               return -EFAULT; /* protects following copy_from_user()s + get_user()s */
+
+       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 (__copy_from_user(hp, buf, SZ_SG_IO_HDR)) {
+               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 (sg_res_in_use(sfp)) {
+                       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 (!access_ok(VERIFY_READ, hp->cmdp, hp->cmd_len)) {
+               sg_remove_request(sfp, srp);
+               return -EFAULT; /* protects following copy_from_user()s + get_user()s */
+       }
+       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));
+
+       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);
+               return k;       /* probably out of space --> ENOMEM */
+       }
+       if (atomic_read(&sdp->detaching)) {
+               if (srp->bio)
+                       blk_end_request_all(srp->rq, -EIO);
+               sg_finish_rem_req(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(). */
+       blk_execute_rq_nowait(sdp->device->request_queue, sdp->disk,
+                             srp->rq, at_head, sg_rq_end_io);
+       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 long
+sg_ioctl(struct file *filp, unsigned int cmd_in, unsigned long arg)
+{
+       void __user *p = (void __user *)arg;
+       int __user *ip = p;
+       int result, val, read_only;
+       Sg_device *sdp;
+       Sg_fd *sfp;
+       Sg_request *srp;
+       unsigned long iflags;
+
+       if ((!(sfp = (Sg_fd *) filp->private_data)) || (!(sdp = sfp->parentdp)))
+               return -ENXIO;
+
+       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;
+               if (!access_ok(VERIFY_WRITE, p, SZ_SG_IO_HDR))
+                       return -EFAULT;
+               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) || atomic_read(&sdp->detaching)));
+               if (atomic_read(&sdp->detaching))
+                       return -ENODEV;
+               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 >= MULDIV (INT_MAX, USER_HZ, HZ))
+                   val = MULDIV (INT_MAX, USER_HZ, HZ);
+               sfp->timeout_user = val;
+               sfp->timeout = MULDIV (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:
+               result = get_user(val, ip);
+               if (result)
+                       return result;
+               if (val) {
+                       sfp->low_dma = 1;
+                       if ((0 == sfp->low_dma) && (0 == sg_res_in_use(sfp))) {
+                               val = (int) sfp->reserve.bufflen;
+                               sg_remove_scat(sfp, &sfp->reserve);
+                               sg_build_reserve(sfp, val);
+                       }
+               } else {
+                       if (atomic_read(&sdp->detaching))
+                               return -ENODEV;
+                       sfp->low_dma = sdp->device->host->unchecked_isa_dma;
+               }
+               return 0;
+       case SG_GET_LOW_DMA:
+               return put_user((int) sfp->low_dma, ip);
+       case SG_GET_SCSI_ID:
+               if (!access_ok(VERIFY_WRITE, p, sizeof (sg_scsi_id_t)))
+                       return -EFAULT;
+               else {
+                       sg_scsi_id_t __user *sg_idp = p;
+
+                       if (atomic_read(&sdp->detaching))
+                               return -ENODEV;
+                       __put_user((int) sdp->device->host->host_no,
+                                  &sg_idp->host_no);
+                       __put_user((int) sdp->device->channel,
+                                  &sg_idp->channel);
+                       __put_user((int) sdp->device->id, &sg_idp->scsi_id);
+                       __put_user((int) sdp->device->lun, &sg_idp->lun);
+                       __put_user((int) sdp->device->type, &sg_idp->scsi_type);
+                       __put_user((short) sdp->device->host->cmd_per_lun,
+                                  &sg_idp->h_cmd_per_lun);
+                       __put_user((short) sdp->device->queue_depth,
+                                  &sg_idp->d_queue_depth);
+                       __put_user(0, &sg_idp->unused[0]);
+                       __put_user(0, &sg_idp->unused[1]);
+                       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:
+               if (!access_ok(VERIFY_WRITE, ip, sizeof (int)))
+                       return -EFAULT;
+               read_lock_irqsave(&sfp->rq_list_lock, iflags);
+               for (srp = sfp->headrp; srp; srp = srp->nextrp) {
+                       if ((1 == srp->done) && (!srp->sg_io_owned)) {
+                               read_unlock_irqrestore(&sfp->rq_list_lock,
+                                                      iflags);
+                               __put_user(srp->header.pack_id, ip);
+                               return 0;
+                       }
+               }
+               read_unlock_irqrestore(&sfp->rq_list_lock, iflags);
+               __put_user(-1, ip);
+               return 0;
+       case SG_GET_NUM_WAITING:
+               read_lock_irqsave(&sfp->rq_list_lock, iflags);
+               for (val = 0, srp = sfp->headrp; srp; srp = srp->nextrp) {
+                       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));
+               if (val != sfp->reserve.bufflen) {
+                       if (sg_res_in_use(sfp) || sfp->mmap_called)
+                               return -EBUSY;
+                       sg_remove_scat(sfp, &sfp->reserve);
+                       sg_build_reserve(sfp, val);
+               }
+               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;
+               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:
+               if (!access_ok(VERIFY_WRITE, p, SZ_SG_REQ_INFO * SG_MAX_QUEUE))
+                       return -EFAULT;
+               else {
+                       sg_req_info_t *rinfo;
+                       unsigned int ms;
+
+                       rinfo = kmalloc(SZ_SG_REQ_INFO * SG_MAX_QUEUE,
+                                                               GFP_KERNEL);
+                       if (!rinfo)
+                               return -ENOMEM;
+                       read_lock_irqsave(&sfp->rq_list_lock, iflags);
+                       for (srp = sfp->headrp, val = 0; val < SG_MAX_QUEUE;
+                            ++val, srp = srp ? srp->nextrp : srp) {
+                               memset(&rinfo[val], 0, SZ_SG_REQ_INFO);
+                               if (srp) {
+                                       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;
+                               }
+                       }
+                       read_unlock_irqrestore(&sfp->rq_list_lock, iflags);
+                       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;
+               if (read_only) {
+                       unsigned char opcode = WRITE_6;
+                       Scsi_Ioctl_Command __user *siocp = p;
+
+                       if (copy_from_user(&opcode, siocp->data, 1))
+                               return -EFAULT;
+                       if (sg_allow_access(filp, &opcode))
+                               return -EPERM;
+               }
+               return sg_scsi_ioctl(sdp->device->request_queue, NULL, filp->f_mode, 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->disk->disk_name,
+                                      MKDEV(SCSI_GENERIC_MAJOR, sdp->index),
+                                      NULL,
+                                      (char *)arg);
+       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 scsi_ioctl(sdp->device, cmd_in, p);
+}
+
+#ifdef CONFIG_COMPAT
+static long sg_compat_ioctl(struct file *filp, unsigned int cmd_in, unsigned long arg)
+{
+       Sg_device *sdp;
+       Sg_fd *sfp;
+       struct scsi_device *sdev;
+
+       if ((!(sfp = (Sg_fd *) filp->private_data)) || (!(sdp = sfp->parentdp)))
+               return -ENXIO;
+
+       sdev = sdp->device;
+       if (sdev->host->hostt->compat_ioctl) { 
+               int ret;
+
+               ret = sdev->host->hostt->compat_ioctl(sdev, cmd_in, (void __user *)arg);
+
+               return ret;
+       }
+       
+       return -ENOIOCTLCMD;
+}
+#endif
+
+static unsigned int
+sg_poll(struct file *filp, poll_table * wait)
+{
+       unsigned int res = 0;
+       Sg_device *sdp;
+       Sg_fd *sfp;
+       Sg_request *srp;
+       int count = 0;
+       unsigned long iflags;
+
+       sfp = filp->private_data;
+       if (!sfp)
+               return POLLERR;
+       sdp = sfp->parentdp;
+       if (!sdp)
+               return POLLERR;
+       poll_wait(filp, &sfp->read_wait, wait);
+       read_lock_irqsave(&sfp->rq_list_lock, iflags);
+       for (srp = sfp->headrp; srp; srp = srp->nextrp) {
+               /* if any read waiting, flag it */
+               if ((0 == res) && (1 == srp->done) && (!srp->sg_io_owned))
+                       res = POLLIN | POLLRDNORM;
+               ++count;
+       }
+       read_unlock_irqrestore(&sfp->rq_list_lock, iflags);
+
+       if (atomic_read(&sdp->detaching))
+               res |= POLLHUP;
+       else if (!sfp->cmd_q) {
+               if (0 == count)
+                       res |= POLLOUT | POLLWRNORM;
+       } else if (count < SG_MAX_QUEUE)
+               res |= POLLOUT | POLLWRNORM;
+       SCSI_LOG_TIMEOUT(3, sg_printk(KERN_INFO, sdp,
+                                     "sg_poll: res=0x%x\n", (int) 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 int
+sg_vma_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
+{
+       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;
+
+       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;
+       if (req_sz > rsv_schp->bufflen)
+               return -ENOMEM; /* cannot map more than reserved buffer */
+
+       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_DONTEXPAND | VM_DONTDUMP;
+       vma->vm_private_data = sfp;
+       vma->vm_ops = &sg_mmap_vm_ops;
+       return 0;
+}
+
+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);
+       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, int uptodate)
+{
+       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 = rq->sense;
+       result = rq->errors;
+       resid = rq->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 = msg_byte(result);
+               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;
+               }
+       }
+       /* 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;
+       if (rq->cmd != rq->__cmd)
+               kfree(rq->cmd);
+       __blk_put_request(rq->q, 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,
+#ifdef CONFIG_COMPAT
+       .compat_ioctl = sg_compat_ioctl,
+#endif
+       .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 gendisk *disk, 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(disk->disk_name, "sg%d", k);
+       disk->first_minor = k;
+       sdp->disk = disk;
+       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);
+       struct gendisk *disk;
+       Sg_device *sdp = NULL;
+       struct cdev * cdev = NULL;
+       int error;
+       unsigned long iflags;
+
+       disk = alloc_disk(1);
+       if (!disk) {
+               pr_warn("%s: alloc_disk failed\n", __func__);
+               return -ENOMEM;
+       }
+       disk->major = SCSI_GENERIC_MAJOR;
+
+       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(disk, 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", disk->disk_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:
+       put_disk(disk);
+       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"));
+
+       put_disk(sdp->disk);
+       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))");
+
+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);
+err_out:
+       unregister_chrdev_region(MKDEV(SCSI_GENERIC_MAJOR, 0), SG_MAX_DEVS);
+       return rc;
+}
+
+static void __exit
+exit_sg(void)
+{
+#ifdef CONFIG_SCSI_PROC_FS
+       sg_proc_cleanup();
+#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;
+       unsigned char *long_cmdp = NULL;
+
+       SCSI_LOG_TIMEOUT(4, sg_printk(KERN_INFO, sfp->parentdp,
+                                     "sg_start_req: dxfer_len=%d\n",
+                                     dxfer_len));
+
+       if (hp->cmd_len > BLK_MAX_CDB) {
+               long_cmdp = kzalloc(hp->cmd_len, GFP_KERNEL);
+               if (!long_cmdp)
+                       return -ENOMEM;
+       }
+
+       /*
+        * 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 using GFP_ATOMIC with
+        * blk_get_request() will return -EWOULDBLOCK, whereas using GFP_KERNEL
+        * will cause blk_get_request() to sleep until an active command
+        * completes, freeing up a request.  Neither option is ideal, but
+        * GFP_KERNEL is the better choice to prevent userspace from getting an
+        * unexpected EWOULDBLOCK.
+        *
+        * With scsi-mq disabled, blk_get_request() with GFP_KERNEL usually
+        * does not sleep except under memory pressure.
+        */
+       rq = blk_get_request(q, rw, GFP_KERNEL);
+       if (IS_ERR(rq)) {
+               kfree(long_cmdp);
+               return PTR_ERR(rq);
+       }
+
+       blk_rq_set_block_pc(rq);
+
+       if (hp->cmd_len > BLK_MAX_CDB)
+               rq->cmd = long_cmdp;
+       memcpy(rq->cmd, cmd, hp->cmd_len);
+       rq->cmd_len = hp->cmd_len;
+
+       srp->rq = rq;
+       rq->end_io_data = srp;
+       rq->sense = srp->sense_b;
+       rq->retries = 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 &&
+           !sfp->parentdp->device->host->unchecked_isa_dma &&
+           blk_rq_aligned(q, (unsigned long)hp->dxferp, dxfer_len))
+               md = NULL;
+       else
+               md = &map_data;
+
+       if (md) {
+               if (!sg_res_in_use(sfp) && dxfer_len <= rsv_schp->bufflen)
+                       sg_link_reserve(sfp, srp, dxfer_len);
+               else {
+                       res = sg_build_indirect(req_schp, sfp, dxfer_len);
+                       if (res)
+                               return res;
+               }
+
+               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);
+
+               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) {
+               if (srp->rq->cmd != srp->rq->__cmd)
+                       kfree(srp->rq->cmd);
+               blk_put_request(srp->rq);
+       }
+
+       if (srp->res_used)
+               sg_unlink_reserve(sfp, srp);
+       else
+               sg_remove_scat(sfp, req_schp);
+
+       sg_remove_request(sfp, srp);
+
+       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;
+
+       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;
+       }
+
+       if (sfp->low_dma)
+               gfp_mask |= GFP_DMA;
+
+       if (!capable(CAP_SYS_ADMIN) || !capable(CAP_SYS_RAWIO))
+               gfp_mask |= __GFP_ZERO;
+
+       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;
+       sfp->save_scat_len = 0;
+       srp->res_used = 0;
+}
+
+static Sg_request *
+sg_get_rq_mark(Sg_fd * sfp, int pack_id)
+{
+       Sg_request *resp;
+       unsigned long iflags;
+
+       write_lock_irqsave(&sfp->rq_list_lock, iflags);
+       for (resp = sfp->headrp; resp; resp = resp->nextrp) {
+               /* look for requests that are ready + not SG_IO owned */
+               if ((1 == resp->done) && (!resp->sg_io_owned) &&
+                   ((-1 == pack_id) || (resp->header.pack_id == pack_id))) {
+                       resp->done = 2; /* guard against other readers */
+                       break;
+               }
+       }
+       write_unlock_irqrestore(&sfp->rq_list_lock, iflags);
+       return resp;
+}
+
+/* always adds to end of list */
+static Sg_request *
+sg_add_request(Sg_fd * sfp)
+{
+       int k;
+       unsigned long iflags;
+       Sg_request *resp;
+       Sg_request *rp = sfp->req_arr;
+
+       write_lock_irqsave(&sfp->rq_list_lock, iflags);
+       resp = sfp->headrp;
+       if (!resp) {
+               memset(rp, 0, sizeof (Sg_request));
+               rp->parentfp = sfp;
+               resp = rp;
+               sfp->headrp = resp;
+       } else {
+               if (0 == sfp->cmd_q)
+                       resp = NULL;    /* command queuing disallowed */
+               else {
+                       for (k = 0; k < SG_MAX_QUEUE; ++k, ++rp) {
+                               if (!rp->parentfp)
+                                       break;
+                       }
+                       if (k < SG_MAX_QUEUE) {
+                               memset(rp, 0, sizeof (Sg_request));
+                               rp->parentfp = sfp;
+                               while (resp->nextrp)
+                                       resp = resp->nextrp;
+                               resp->nextrp = rp;
+                               resp = rp;
+                       } else
+                               resp = NULL;
+               }
+       }
+       if (resp) {
+               resp->nextrp = NULL;
+               resp->header.duration = jiffies_to_msecs(jiffies);
+       }
+       write_unlock_irqrestore(&sfp->rq_list_lock, iflags);
+       return resp;
+}
+
+/* Return of 1 for found; 0 for not found */
+static int
+sg_remove_request(Sg_fd * sfp, Sg_request * srp)
+{
+       Sg_request *prev_rp;
+       Sg_request *rp;
+       unsigned long iflags;
+       int res = 0;
+
+       if ((!sfp) || (!srp) || (!sfp->headrp))
+               return res;
+       write_lock_irqsave(&sfp->rq_list_lock, iflags);
+       prev_rp = sfp->headrp;
+       if (srp == prev_rp) {
+               sfp->headrp = prev_rp->nextrp;
+               prev_rp->parentfp = NULL;
+               res = 1;
+       } else {
+               while ((rp = prev_rp->nextrp)) {
+                       if (srp == rp) {
+                               prev_rp->nextrp = rp->nextrp;
+                               rp->parentfp = NULL;
+                               res = 1;
+                               break;
+                       }
+                       prev_rp = rp;
+               }
+       }
+       write_unlock_irqrestore(&sfp->rq_list_lock, iflags);
+       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);
+
+       kref_init(&sfp->f_ref);
+       sfp->timeout = SG_DEFAULT_TIMEOUT;
+       sfp->timeout_user = SG_DEFAULT_TIMEOUT_USER;
+       sfp->force_packid = SG_DEF_FORCE_PACK_ID;
+       sfp->low_dma = (SG_DEF_FORCE_LOW_DMA == 0) ?
+           sdp->device->host->unchecked_isa_dma : 1;
+       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);
+               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;
+
+       /* Cleanup any responses which were never read(). */
+       while (sfp->headrp)
+               sg_finish_rem_req(sfp->headrp);
+
+       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);
+}
+
+static int
+sg_res_in_use(Sg_fd * sfp)
+{
+       const Sg_request *srp;
+       unsigned long iflags;
+
+       read_lock_irqsave(&sfp->rq_list_lock, iflags);
+       for (srp = sfp->headrp; srp; srp = srp->nextrp)
+               if (srp->res_used)
+                       break;
+       read_unlock_irqrestore(&sfp->rq_list_lock, iflags);
+       return srp ? 1 : 0;
+}
+
+#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 struct proc_dir_entry *sg_proc_sgp = NULL;
+
+static char sg_proc_sg_dirname[] = "scsi/sg";
+
+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 file_operations adio_fops = {
+       .owner = THIS_MODULE,
+       .open = sg_proc_single_open_adio,
+       .read = seq_read,
+       .llseek = seq_lseek,
+       .write = sg_proc_write_adio,
+       .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 file_operations dressz_fops = {
+       .owner = THIS_MODULE,
+       .open = sg_proc_single_open_dressz,
+       .read = seq_read,
+       .llseek = seq_lseek,
+       .write = sg_proc_write_dressz,
+       .release = single_release,
+};
+
+static int sg_proc_seq_show_version(struct seq_file *s, void *v);
+static int sg_proc_single_open_version(struct inode *inode, struct file *file);
+static const struct file_operations version_fops = {
+       .owner = THIS_MODULE,
+       .open = sg_proc_single_open_version,
+       .read = seq_read,
+       .llseek = seq_lseek,
+       .release = single_release,
+};
+
+static int sg_proc_seq_show_devhdr(struct seq_file *s, void *v);
+static int sg_proc_single_open_devhdr(struct inode *inode, struct file *file);
+static const struct file_operations devhdr_fops = {
+       .owner = THIS_MODULE,
+       .open = sg_proc_single_open_devhdr,
+       .read = seq_read,
+       .llseek = seq_lseek,
+       .release = single_release,
+};
+
+static int sg_proc_seq_show_dev(struct seq_file *s, void *v);
+static int sg_proc_open_dev(struct inode *inode, struct file *file);
+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 file_operations dev_fops = {
+       .owner = THIS_MODULE,
+       .open = sg_proc_open_dev,
+       .read = seq_read,
+       .llseek = seq_lseek,
+       .release = seq_release,
+};
+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 int sg_proc_open_devstrs(struct inode *inode, struct file *file);
+static const struct file_operations devstrs_fops = {
+       .owner = THIS_MODULE,
+       .open = sg_proc_open_devstrs,
+       .read = seq_read,
+       .llseek = seq_lseek,
+       .release = seq_release,
+};
+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 int sg_proc_open_debug(struct inode *inode, struct file *file);
+static const struct file_operations debug_fops = {
+       .owner = THIS_MODULE,
+       .open = sg_proc_open_debug,
+       .read = seq_read,
+       .llseek = seq_lseek,
+       .release = seq_release,
+};
+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,
+};
+
+
+struct sg_proc_leaf {
+       const char * name;
+       const struct file_operations * fops;
+};
+
+static const struct sg_proc_leaf sg_proc_leaf_arr[] = {
+       {"allow_dio", &adio_fops},
+       {"debug", &debug_fops},
+       {"def_reserved_size", &dressz_fops},
+       {"device_hdr", &devhdr_fops},
+       {"devices", &dev_fops},
+       {"device_strs", &devstrs_fops},
+       {"version", &version_fops}
+};
+
+static int
+sg_proc_init(void)
+{
+       int num_leaves = ARRAY_SIZE(sg_proc_leaf_arr);
+       int k;
+
+       sg_proc_sgp = proc_mkdir(sg_proc_sg_dirname, NULL);
+       if (!sg_proc_sgp)
+               return 1;
+       for (k = 0; k < num_leaves; ++k) {
+               const struct sg_proc_leaf *leaf = &sg_proc_leaf_arr[k];
+               umode_t mask = leaf->fops->write ? S_IRUGO | S_IWUSR : S_IRUGO;
+               proc_create(leaf->name, mask, sg_proc_sgp, leaf->fops);
+       }
+       return 0;
+}
+
+static void
+sg_proc_cleanup(void)
+{
+       int k;
+       int num_leaves = ARRAY_SIZE(sg_proc_leaf_arr);
+
+       if (!sg_proc_sgp)
+               return;
+       for (k = 0; k < num_leaves; ++k)
+               remove_proc_entry(sg_proc_leaf_arr[k].name, sg_proc_sgp);
+       remove_proc_entry(sg_proc_sg_dirname, NULL);
+}
+
+
+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_single_open_version(struct inode *inode, struct file *file)
+{
+       return single_open(file, sg_proc_seq_show_version, NULL);
+}
+
+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;
+}
+
+static int sg_proc_single_open_devhdr(struct inode *inode, struct file *file)
+{
+       return single_open(file, sg_proc_seq_show_devhdr, NULL);
+}
+
+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_open_dev(struct inode *inode, struct file *file)
+{
+        return seq_open(file, &dev_seq_ops);
+}
+
+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) atomic_read(&scsidp->device_busy),
+                             (int) scsi_device_online(scsidp));
+       }
+       read_unlock_irqrestore(&sg_index_lock, iflags);
+       return 0;
+}
+
+static int sg_proc_open_devstrs(struct inode *inode, struct file *file)
+{
+        return seq_open(file, &devstrs_seq_ops);
+}
+
+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, m, 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,
+                          (int) fp->low_dma);
+               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);
+               for (m = 0, srp = fp->headrp;
+                               srp != NULL;
+                               ++m, srp = srp->nextrp) {
+                       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 (0 == m)
+                       seq_puts(s, "     No requests active\n");
+               read_unlock(&fp->rq_list_lock);
+       }
+}
+
+static int sg_proc_open_debug(struct inode *inode, struct file *file)
+{
+        return seq_open(file, &debug_seq_ops);
+}
+
+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->disk->disk_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);