/*
 * (C) 2001 Clemson University and The University of Chicago
 *
 * Changes by Acxiom Corporation to add protocol version to kernel
 * communication, Copyright Acxiom Corporation, 2005.
 *
 * See COPYING in top-level directory.
 */

#include "protocol.h"
#include "orangefs-kernel.h"
#include "orangefs-dev-proto.h"
#include "orangefs-bufmap.h"
#include "orangefs-debugfs.h"

#include <linux/debugfs.h>
#include <linux/slab.h>

/* this file implements the /dev/pvfs2-req device node */

uint32_t orangefs_userspace_version;

static int open_access_count;

static DEFINE_MUTEX(devreq_mutex);

#define DUMP_DEVICE_ERROR()                                                   \
do {                                                                          \
        gossip_err("*****************************************************\n");\
        gossip_err("ORANGEFS Device Error:  You cannot open the device file ");  \
        gossip_err("\n/dev/%s more than once.  Please make sure that\nthere " \
                   "are no ", ORANGEFS_REQDEVICE_NAME);                          \
        gossip_err("instances of a program using this device\ncurrently "     \
                   "running. (You must verify this!)\n");                     \
        gossip_err("For example, you can use the lsof program as follows:\n");\
        gossip_err("'lsof | grep %s' (run this as root)\n",                   \
                   ORANGEFS_REQDEVICE_NAME);                                     \
        gossip_err("  open_access_count = %d\n", open_access_count);          \
        gossip_err("*****************************************************\n");\
} while (0)

static int hash_func(__u64 tag, int table_size)
{
        return do_div(tag, (unsigned int)table_size);
}

static void orangefs_devreq_add_op(struct orangefs_kernel_op_s *op)
{
        int index = hash_func(op->tag, hash_table_size);

        list_add_tail(&op->list, &orangefs_htable_ops_in_progress[index]);
}

/*
 * find the op with this tag and remove it from the in progress
 * hash table.
 */
static struct orangefs_kernel_op_s *orangefs_devreq_remove_op(__u64 tag)
{
        struct orangefs_kernel_op_s *op, *next;
        int index;

        index = hash_func(tag, hash_table_size);

        spin_lock(&orangefs_htable_ops_in_progress_lock);
        list_for_each_entry_safe(op,
                                 next,
                                 &orangefs_htable_ops_in_progress[index],
                                 list) {
                if (op->tag == tag && !op_state_purged(op) &&
                    !op_state_given_up(op)) {
                        list_del_init(&op->list);
                        spin_unlock(&orangefs_htable_ops_in_progress_lock);
                        return op;
                }
        }

        spin_unlock(&orangefs_htable_ops_in_progress_lock);
        return NULL;
}

/* Returns whether any FS are still pending remounted */
static int mark_all_pending_mounts(void)
{
        int unmounted = 1;
        struct orangefs_sb_info_s *orangefs_sb = NULL;

        spin_lock(&orangefs_superblocks_lock);
        list_for_each_entry(orangefs_sb, &orangefs_superblocks, list) {
                /* All of these file system require a remount */
                orangefs_sb->mount_pending = 1;
                unmounted = 0;
        }
        spin_unlock(&orangefs_superblocks_lock);
        return unmounted;
}

/*
 * Determine if a given file system needs to be remounted or not
 *  Returns -1 on error
 *           0 if already mounted
 *           1 if needs remount
 */
static int fs_mount_pending(__s32 fsid)
{
        int mount_pending = -1;
        struct orangefs_sb_info_s *orangefs_sb = NULL;

        spin_lock(&orangefs_superblocks_lock);
        list_for_each_entry(orangefs_sb, &orangefs_superblocks, list) {
                if (orangefs_sb->fs_id == fsid) {
                        mount_pending = orangefs_sb->mount_pending;
                        break;
                }
        }
        spin_unlock(&orangefs_superblocks_lock);
        return mount_pending;
}

static int orangefs_devreq_open(struct inode *inode, struct file *file)
{
        int ret = -EINVAL;

        /* in order to ensure that the filesystem driver sees correct UIDs */
        if (file->f_cred->user_ns != &init_user_ns) {
                gossip_err("%s: device cannot be opened outside init_user_ns\n",
                           __func__);
                goto out;
        }

        if (!(file->f_flags & O_NONBLOCK)) {
                gossip_err("%s: device cannot be opened in blocking mode\n",
                           __func__);
                goto out;
        }
        ret = -EACCES;
        gossip_debug(GOSSIP_DEV_DEBUG, "client-core: opening device\n");
        mutex_lock(&devreq_mutex);

        if (open_access_count == 0) {
                open_access_count = 1;
                ret = 0;
        } else {
                DUMP_DEVICE_ERROR();
        }
        mutex_unlock(&devreq_mutex);

out:

        gossip_debug(GOSSIP_DEV_DEBUG,
                     "pvfs2-client-core: open device complete (ret = %d)\n",
                     ret);
        return ret;
}

/* Function for read() callers into the device */
static ssize_t orangefs_devreq_read(struct file *file,
                                 char __user *buf,
                                 size_t count, loff_t *offset)
{
        struct orangefs_kernel_op_s *op, *temp;
        __s32 proto_ver = ORANGEFS_KERNEL_PROTO_VERSION;
        static __s32 magic = ORANGEFS_DEVREQ_MAGIC;
        struct orangefs_kernel_op_s *cur_op = NULL;
        unsigned long ret;

        /* We do not support blocking IO. */
        if (!(file->f_flags & O_NONBLOCK)) {
                gossip_err("%s: blocking read from client-core.\n",
                           __func__);
                return -EINVAL;
        }

        /*
         * The client will do an ioctl to find MAX_DEV_REQ_UPSIZE, then
         * always read with that size buffer.
         */
        if (count != MAX_DEV_REQ_UPSIZE) {
                gossip_err("orangefs: client-core tried to read wrong size\n");
                return -EINVAL;
        }

restart:
        /* Get next op (if any) from top of list. */
        spin_lock(&orangefs_request_list_lock);
        list_for_each_entry_safe(op, temp, &orangefs_request_list, list) {
                __s32 fsid;
                /* This lock is held past the end of the loop when we break. */
                spin_lock(&op->lock);
                if (unlikely(op_state_purged(op) || op_state_given_up(op))) {
                        spin_unlock(&op->lock);
                        continue;
                }

                fsid = fsid_of_op(op);
                if (fsid != ORANGEFS_FS_ID_NULL) {
                        int ret;
                        /* Skip ops whose filesystem needs to be mounted. */
                        ret = fs_mount_pending(fsid);
                        if (ret == 1) {
                                gossip_debug(GOSSIP_DEV_DEBUG,
                                    "%s: mount pending, skipping op tag "
                                    "%llu %s\n",
                                    __func__,
                                    llu(op->tag),
                                    get_opname_string(op));
                                spin_unlock(&op->lock);
                                continue;
                        /*
                         * Skip ops whose filesystem we don't know about unless
                         * it is being mounted.
                         */
                        /* XXX: is there a better way to detect this? */
                        } else if (ret == -1 &&
                                   !(op->upcall.type ==
                                        ORANGEFS_VFS_OP_FS_MOUNT ||
                                     op->upcall.type ==
                                        ORANGEFS_VFS_OP_GETATTR)) {
                                gossip_debug(GOSSIP_DEV_DEBUG,
                                    "orangefs: skipping op tag %llu %s\n",
                                    llu(op->tag), get_opname_string(op));
                                gossip_err(
                                    "orangefs: ERROR: fs_mount_pending %d\n",
                                    fsid);
                                spin_unlock(&op->lock);
                                continue;
                        }
                }
                /*
                 * Either this op does not pertain to a filesystem, is mounting
                 * a filesystem, or pertains to a mounted filesystem. Let it
                 * through.
                 */
                cur_op = op;
                break;
        }

        /*
         * At this point we either have a valid op and can continue or have not
         * found an op and must ask the client to try again later.
         */
        if (!cur_op) {
                spin_unlock(&orangefs_request_list_lock);
                return -EAGAIN;
        }

        gossip_debug(GOSSIP_DEV_DEBUG, "%s: reading op tag %llu %s\n",
                     __func__,
                     llu(cur_op->tag),
                     get_opname_string(cur_op));

        /*
         * Such an op should never be on the list in the first place. If so, we
         * will abort.
         */
        if (op_state_in_progress(cur_op) || op_state_serviced(cur_op)) {
                gossip_err("orangefs: ERROR: Current op already queued.\n");
                list_del_init(&cur_op->list);
                spin_unlock(&cur_op->lock);
                spin_unlock(&orangefs_request_list_lock);
                return -EAGAIN;
        }

        list_del_init(&cur_op->list);
        spin_unlock(&orangefs_request_list_lock);

        spin_unlock(&cur_op->lock);

        /* Push the upcall out. */
        ret = copy_to_user(buf, &proto_ver, sizeof(__s32));
        if (ret != 0)
                goto error;
        ret = copy_to_user(buf+sizeof(__s32), &magic, sizeof(__s32));
        if (ret != 0)
                goto error;
        ret = copy_to_user(buf+2 * sizeof(__s32), &cur_op->tag, sizeof(__u64));
        if (ret != 0)
                goto error;
        ret = copy_to_user(buf+2*sizeof(__s32)+sizeof(__u64), &cur_op->upcall,
                           sizeof(struct orangefs_upcall_s));
        if (ret != 0)
                goto error;

        spin_lock(&orangefs_htable_ops_in_progress_lock);
        spin_lock(&cur_op->lock);
        if (unlikely(op_state_given_up(cur_op))) {
                spin_unlock(&cur_op->lock);
                spin_unlock(&orangefs_htable_ops_in_progress_lock);
                complete(&cur_op->waitq);
                goto restart;
        }

        /*
         * Set the operation to be in progress and move it between lists since
         * it has been sent to the client.
         */
        set_op_state_inprogress(cur_op);
        gossip_debug(GOSSIP_DEV_DEBUG,
                     "%s: 1 op:%s: op_state:%d: process:%s:\n",
                     __func__,
                     get_opname_string(cur_op),
                     cur_op->op_state,
                     current->comm);
        orangefs_devreq_add_op(cur_op);
        spin_unlock(&cur_op->lock);
        spin_unlock(&orangefs_htable_ops_in_progress_lock);

        /* The client only asks to read one size buffer. */
        return MAX_DEV_REQ_UPSIZE;
error:
        /*
         * We were unable to copy the op data to the client. Put the op back in
         * list. If client has crashed, the op will be purged later when the
         * device is released.
         */
        gossip_err("orangefs: Failed to copy data to user space\n");
        spin_lock(&orangefs_request_list_lock);
        spin_lock(&cur_op->lock);
        if (likely(!op_state_given_up(cur_op))) {
                set_op_state_waiting(cur_op);
                gossip_debug(GOSSIP_DEV_DEBUG,
                             "%s: 2 op:%s: op_state:%d: process:%s:\n",
                             __func__,
                             get_opname_string(cur_op),
                             cur_op->op_state,
                             current->comm);
                list_add(&cur_op->list, &orangefs_request_list);
                spin_unlock(&cur_op->lock);
        } else {
                spin_unlock(&cur_op->lock);
                complete(&cur_op->waitq);
        }
        spin_unlock(&orangefs_request_list_lock);
        return -EFAULT;
}

/*
 * Function for writev() callers into the device.
 *
 * Userspace should have written:
 *  - __u32 version
 *  - __u32 magic
 *  - __u64 tag
 *  - struct orangefs_downcall_s
 *  - trailer buffer (in the case of READDIR operations)
 */
static ssize_t orangefs_devreq_write_iter(struct kiocb *iocb,
                                      struct iov_iter *iter)
{
        ssize_t ret;
        struct orangefs_kernel_op_s *op = NULL;
        struct {
                __u32 version;
                __u32 magic;
                __u64 tag;
        } head;
        int total = ret = iov_iter_count(iter);
        int downcall_size = sizeof(struct orangefs_downcall_s);
        int head_size = sizeof(head);

        gossip_debug(GOSSIP_DEV_DEBUG, "%s: total:%d: ret:%zd:\n",
                     __func__,
                     total,
                     ret);

        if (total < MAX_DEV_REQ_DOWNSIZE) {
                gossip_err("%s: total:%d: must be at least:%u:\n",
                           __func__,
                           total,
                           (unsigned int) MAX_DEV_REQ_DOWNSIZE);
                return -EFAULT;
        }
     
        if (!copy_from_iter_full(&head, head_size, iter)) {
                gossip_err("%s: failed to copy head.\n", __func__);
                return -EFAULT;
        }

        if (head.version < ORANGEFS_MINIMUM_USERSPACE_VERSION) {
                gossip_err("%s: userspace claims version"
                           "%d, minimum version required: %d.\n",
                           __func__,
                           head.version,
                           ORANGEFS_MINIMUM_USERSPACE_VERSION);
                return -EPROTO;
        }

        if (head.magic != ORANGEFS_DEVREQ_MAGIC) {
                gossip_err("Error: Device magic number does not match.\n");
                return -EPROTO;
        }

        if (!orangefs_userspace_version) {
                orangefs_userspace_version = head.version;
        } else if (orangefs_userspace_version != head.version) {
                gossip_err("Error: userspace version changes\n");
                return -EPROTO;
        }

        /* remove the op from the in progress hash table */
        op = orangefs_devreq_remove_op(head.tag);
        if (!op) {
                gossip_err("WARNING: No one's waiting for tag %llu\n",
                           llu(head.tag));
                return ret;
        }

        if (!copy_from_iter_full(&op->downcall, downcall_size, iter)) {
                gossip_err("%s: failed to copy downcall.\n", __func__);
                goto Efault;
        }

        if (op->downcall.status)
                goto wakeup;

        /*
         * We've successfully peeled off the head and the downcall. 
         * Something has gone awry if total doesn't equal the
         * sum of head_size, downcall_size and trailer_size.
         */
        if ((head_size + downcall_size + op->downcall.trailer_size) != total) {
                gossip_err("%s: funky write, head_size:%d"
                           ": downcall_size:%d: trailer_size:%lld"
                           ": total size:%d:\n",
                           __func__,
                           head_size,
                           downcall_size,
                           op->downcall.trailer_size,
                           total);
                goto Efault;
        }

        /* Only READDIR operations should have trailers. */
        if ((op->downcall.type != ORANGEFS_VFS_OP_READDIR) &&
            (op->downcall.trailer_size != 0)) {
                gossip_err("%s: %x operation with trailer.",
                           __func__,
                           op->downcall.type);
                goto Efault;
        }

        /* READDIR operations should always have trailers. */
        if ((op->downcall.type == ORANGEFS_VFS_OP_READDIR) &&
            (op->downcall.trailer_size == 0)) {
                gossip_err("%s: %x operation with no trailer.",
                           __func__,
                           op->downcall.type);
                goto Efault;
        }

        if (op->downcall.type != ORANGEFS_VFS_OP_READDIR)
                goto wakeup;

        op->downcall.trailer_buf =
                vmalloc(op->downcall.trailer_size);
        if (op->downcall.trailer_buf == NULL) {
                gossip_err("%s: failed trailer vmalloc.\n",
                           __func__);
                goto Enomem;
        }
        memset(op->downcall.trailer_buf, 0, op->downcall.trailer_size);
        if (!copy_from_iter_full(op->downcall.trailer_buf,
                                 op->downcall.trailer_size, iter)) {
                gossip_err("%s: failed to copy trailer.\n", __func__);
                vfree(op->downcall.trailer_buf);
                goto Efault;
        }

wakeup:
        /*
         * Return to vfs waitqueue, and back to service_operation
         * through wait_for_matching_downcall. 
         */
        spin_lock(&op->lock);
        if (unlikely(op_is_cancel(op))) {
                spin_unlock(&op->lock);
                put_cancel(op);
        } else if (unlikely(op_state_given_up(op))) {
                spin_unlock(&op->lock);
                complete(&op->waitq);
        } else {
                set_op_state_serviced(op);
                gossip_debug(GOSSIP_DEV_DEBUG,
                             "%s: op:%s: op_state:%d: process:%s:\n",
                             __func__,
                             get_opname_string(op),
                             op->op_state,
                             current->comm);
                spin_unlock(&op->lock);
        }
        return ret;

Efault:
        op->downcall.status = -(ORANGEFS_ERROR_BIT | 9);
        ret = -EFAULT;
        goto wakeup;

Enomem:
        op->downcall.status = -(ORANGEFS_ERROR_BIT | 8);
        ret = -ENOMEM;
        goto wakeup;
}

/*
 * NOTE: gets called when the last reference to this device is dropped.
 * Using the open_access_count variable, we enforce a reference count
 * on this file so that it can be opened by only one process at a time.
 * the devreq_mutex is used to make sure all i/o has completed
 * before we call orangefs_bufmap_finalize, and similar such tricky
 * situations
 */
static int orangefs_devreq_release(struct inode *inode, struct file *file)
{
        int unmounted = 0;

        gossip_debug(GOSSIP_DEV_DEBUG,
                     "%s:pvfs2-client-core: exiting, closing device\n",
                     __func__);

        mutex_lock(&devreq_mutex);
        orangefs_bufmap_finalize();

        open_access_count = -1;

        unmounted = mark_all_pending_mounts();
        gossip_debug(GOSSIP_DEV_DEBUG, "ORANGEFS Device Close: Filesystem(s) %s\n",
                     (unmounted ? "UNMOUNTED" : "MOUNTED"));

        purge_waiting_ops();
        purge_inprogress_ops();

        orangefs_bufmap_run_down();

        gossip_debug(GOSSIP_DEV_DEBUG,
                     "pvfs2-client-core: device close complete\n");
        open_access_count = 0;
        orangefs_userspace_version = 0;
        mutex_unlock(&devreq_mutex);
        return 0;
}

int is_daemon_in_service(void)
{
        int in_service;

        /*
         * What this function does is checks if client-core is alive
         * based on the access count we maintain on the device.
         */
        mutex_lock(&devreq_mutex);
        in_service = open_access_count == 1 ? 0 : -EIO;
        mutex_unlock(&devreq_mutex);
        return in_service;
}

bool __is_daemon_in_service(void)
{
        return open_access_count == 1;
}

static inline long check_ioctl_command(unsigned int command)
{
        /* Check for valid ioctl codes */
        if (_IOC_TYPE(command) != ORANGEFS_DEV_MAGIC) {
                gossip_err("device ioctl magic numbers don't match! Did you rebuild pvfs2-client-core/libpvfs2? [cmd %x, magic %x != %x]\n",
                        command,
                        _IOC_TYPE(command),
                        ORANGEFS_DEV_MAGIC);
                return -EINVAL;
        }
        /* and valid ioctl commands */
        if (_IOC_NR(command) >= ORANGEFS_DEV_MAXNR || _IOC_NR(command) <= 0) {
                gossip_err("Invalid ioctl command number [%d >= %d]\n",
                           _IOC_NR(command), ORANGEFS_DEV_MAXNR);
                return -ENOIOCTLCMD;
        }
        return 0;
}

static long dispatch_ioctl_command(unsigned int command, unsigned long arg)
{
        static __s32 magic = ORANGEFS_DEVREQ_MAGIC;
        static __s32 max_up_size = MAX_DEV_REQ_UPSIZE;
        static __s32 max_down_size = MAX_DEV_REQ_DOWNSIZE;
        struct ORANGEFS_dev_map_desc user_desc;
        int ret = 0;
        int upstream_kmod = 1;
        struct orangefs_sb_info_s *orangefs_sb;

        /* mtmoore: add locking here */

        switch (command) {
        case ORANGEFS_DEV_GET_MAGIC:
                return ((put_user(magic, (__s32 __user *) arg) == -EFAULT) ?
                        -EIO :
                        0);
        case ORANGEFS_DEV_GET_MAX_UPSIZE:
                return ((put_user(max_up_size,
                                  (__s32 __user *) arg) == -EFAULT) ?
                                        -EIO :
                                        0);
        case ORANGEFS_DEV_GET_MAX_DOWNSIZE:
                return ((put_user(max_down_size,
                                  (__s32 __user *) arg) == -EFAULT) ?
                                        -EIO :
                                        0);
        case ORANGEFS_DEV_MAP:
                ret = copy_from_user(&user_desc,
                                     (struct ORANGEFS_dev_map_desc __user *)
                                     arg,
                                     sizeof(struct ORANGEFS_dev_map_desc));
                /* WTF -EIO and not -EFAULT? */
                return ret ? -EIO : orangefs_bufmap_initialize(&user_desc);
        case ORANGEFS_DEV_REMOUNT_ALL:
                gossip_debug(GOSSIP_DEV_DEBUG,
                             "%s: got ORANGEFS_DEV_REMOUNT_ALL\n",
                             __func__);

                /*
                 * remount all mounted orangefs volumes to regain the lost
                 * dynamic mount tables (if any) -- NOTE: this is done
                 * without keeping the superblock list locked due to the
                 * upcall/downcall waiting.  also, the request mutex is
                 * used to ensure that no operations will be serviced until
                 * all of the remounts are serviced (to avoid ops between
                 * mounts to fail)
                 */
                ret = mutex_lock_interruptible(&orangefs_request_mutex);
                if (ret < 0)
                        return ret;
                gossip_debug(GOSSIP_DEV_DEBUG,
                             "%s: priority remount in progress\n",
                             __func__);
                spin_lock(&orangefs_superblocks_lock);
                list_for_each_entry(orangefs_sb, &orangefs_superblocks, list) {
                        /*
                         * We have to drop the spinlock, so entries can be
                         * removed.  They can't be freed, though, so we just
                         * keep the forward pointers and zero the back ones -
                         * that way we can get to the rest of the list.
                         */
                        if (!orangefs_sb->list.prev)
                                continue;
                        gossip_debug(GOSSIP_DEV_DEBUG,
                                     "%s: Remounting SB %p\n",
                                     __func__,
                                     orangefs_sb);

                        spin_unlock(&orangefs_superblocks_lock);
                        ret = orangefs_remount(orangefs_sb);
                        spin_lock(&orangefs_superblocks_lock);
                        if (ret) {
                                gossip_debug(GOSSIP_DEV_DEBUG,
                                             "SB %p remount failed\n",
                                             orangefs_sb);
                                break;
                        }
                }
                spin_unlock(&orangefs_superblocks_lock);
                gossip_debug(GOSSIP_DEV_DEBUG,
                             "%s: priority remount complete\n",
                             __func__);
                mutex_unlock(&orangefs_request_mutex);
                return ret;

        case ORANGEFS_DEV_UPSTREAM:
                ret = copy_to_user((void __user *)arg,
                                    &upstream_kmod,
                                    sizeof(upstream_kmod));

                if (ret != 0)
                        return -EIO;
                else
                        return ret;

        case ORANGEFS_DEV_CLIENT_MASK:
                return orangefs_debugfs_new_client_mask((void __user *)arg);
        case ORANGEFS_DEV_CLIENT_STRING:
                return orangefs_debugfs_new_client_string((void __user *)arg);
        case ORANGEFS_DEV_DEBUG:
                return orangefs_debugfs_new_debug((void __user *)arg);
        default:
                return -ENOIOCTLCMD;
        }
        return -ENOIOCTLCMD;
}

static long orangefs_devreq_ioctl(struct file *file,
                               unsigned int command, unsigned long arg)
{
        long ret;

        /* Check for properly constructed commands */
        ret = check_ioctl_command(command);
        if (ret < 0)
                return (int)ret;

        return (int)dispatch_ioctl_command(command, arg);
}

#ifdef CONFIG_COMPAT            /* CONFIG_COMPAT is in .config */

/*  Compat structure for the ORANGEFS_DEV_MAP ioctl */
struct ORANGEFS_dev_map_desc32 {
        compat_uptr_t ptr;
        __s32 total_size;
        __s32 size;
        __s32 count;
};

static unsigned long translate_dev_map26(unsigned long args, long *error)
{
        struct ORANGEFS_dev_map_desc32 __user *p32 = (void __user *)args;
        /*
         * Depending on the architecture, allocate some space on the
         * user-call-stack based on our expected layout.
         */
        struct ORANGEFS_dev_map_desc __user *p =
            compat_alloc_user_space(sizeof(*p));
        compat_uptr_t addr;

        *error = 0;
        /* get the ptr from the 32 bit user-space */
        if (get_user(addr, &p32->ptr))
                goto err;
        /* try to put that into a 64-bit layout */
        if (put_user(compat_ptr(addr), &p->ptr))
                goto err;
        /* copy the remaining fields */
        if (copy_in_user(&p->total_size, &p32->total_size, sizeof(__s32)))
                goto err;
        if (copy_in_user(&p->size, &p32->size, sizeof(__s32)))
                goto err;
        if (copy_in_user(&p->count, &p32->count, sizeof(__s32)))
                goto err;
        return (unsigned long)p;
err:
        *error = -EFAULT;
        return 0;
}

/*
 * 32 bit user-space apps' ioctl handlers when kernel modules
 * is compiled as a 64 bit one
 */
static long orangefs_devreq_compat_ioctl(struct file *filp, unsigned int cmd,
                                      unsigned long args)
{
        long ret;
        unsigned long arg = args;

        /* Check for properly constructed commands */
        ret = check_ioctl_command(cmd);
        if (ret < 0)
                return ret;
        if (cmd == ORANGEFS_DEV_MAP) {
                /*
                 * convert the arguments to what we expect internally
                 * in kernel space
                 */
                arg = translate_dev_map26(args, &ret);
                if (ret < 0) {
                        gossip_err("Could not translate dev map\n");
                        return ret;
                }
        }
        /* no other ioctl requires translation */
        return dispatch_ioctl_command(cmd, arg);
}

#endif /* CONFIG_COMPAT is in .config */

/* the assigned character device major number */
static int orangefs_dev_major;

/*
 * Initialize orangefs device specific state:
 * Must be called at module load time only
 */
int orangefs_dev_init(void)
{
        /* register orangefs-req device  */
        orangefs_dev_major = register_chrdev(0,
                                          ORANGEFS_REQDEVICE_NAME,
                                          &orangefs_devreq_file_operations);
        if (orangefs_dev_major < 0) {
                gossip_debug(GOSSIP_DEV_DEBUG,
                             "Failed to register /dev/%s (error %d)\n",
                             ORANGEFS_REQDEVICE_NAME, orangefs_dev_major);
                return orangefs_dev_major;
        }

        gossip_debug(GOSSIP_DEV_DEBUG,
                     "*** /dev/%s character device registered ***\n",
                     ORANGEFS_REQDEVICE_NAME);
        gossip_debug(GOSSIP_DEV_DEBUG, "'mknod /dev/%s c %d 0'.\n",
                     ORANGEFS_REQDEVICE_NAME, orangefs_dev_major);
        return 0;
}

void orangefs_dev_cleanup(void)
{
        unregister_chrdev(orangefs_dev_major, ORANGEFS_REQDEVICE_NAME);
        gossip_debug(GOSSIP_DEV_DEBUG,
                     "*** /dev/%s character device unregistered ***\n",
                     ORANGEFS_REQDEVICE_NAME);
}

static unsigned int orangefs_devreq_poll(struct file *file,
                                      struct poll_table_struct *poll_table)
{
        int poll_revent_mask = 0;

        poll_wait(file, &orangefs_request_list_waitq, poll_table);

        if (!list_empty(&orangefs_request_list))
                poll_revent_mask |= POLL_IN;
        return poll_revent_mask;
}

const struct file_operations orangefs_devreq_file_operations = {
        .owner = THIS_MODULE,
        .read = orangefs_devreq_read,
        .write_iter = orangefs_devreq_write_iter,
        .open = orangefs_devreq_open,
        .release = orangefs_devreq_release,
        .unlocked_ioctl = orangefs_devreq_ioctl,

#ifdef CONFIG_COMPAT            /* CONFIG_COMPAT is in .config */
        .compat_ioctl = orangefs_devreq_compat_ioctl,
#endif
        .poll = orangefs_devreq_poll
};