/*
 * osd_uld.c - OSD Upper Layer Driver
 *
 * A Linux driver module that registers as a SCSI ULD and probes
 * for OSD type SCSI devices.
 * It's main function is to export osd devices to in-kernel users like
 * osdfs and pNFS-objects-LD. It also provides one ioctl for running
 * in Kernel tests.
 *
 * Copyright (C) 2008 Panasas Inc.  All rights reserved.
 *
 * Authors:
 *   Boaz Harrosh <bharrosh@panasas.com>
 *   Benny Halevy <bhalevy@panasas.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 *  1. Redistributions of source code must retain the above copyright
 *     notice, this list of conditions and the following disclaimer.
 *  2. Redistributions in binary form must reproduce the above copyright
 *     notice, this list of conditions and the following disclaimer in the
 *     documentation and/or other materials provided with the distribution.
 *  3. Neither the name of the Panasas company nor the names of its
 *     contributors may be used to endorse or promote products derived
 *     from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
 * BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include <linux/namei.h>
#include <linux/cdev.h>
#include <linux/fs.h>
#include <linux/module.h>
#include <linux/device.h>
#include <linux/idr.h>
#include <linux/major.h>
#include <linux/file.h>
#include <linux/slab.h>

#include <scsi/scsi.h>
#include <scsi/scsi_driver.h>
#include <scsi/scsi_device.h>
#include <scsi/scsi_ioctl.h>

#include <scsi/osd_initiator.h>
#include <scsi/osd_sec.h>

#include "osd_debug.h"

#ifndef TYPE_OSD
#  define TYPE_OSD 0x11
#endif

#ifndef SCSI_OSD_MAJOR
#  define SCSI_OSD_MAJOR 260
#endif
#define SCSI_OSD_MAX_MINOR 64

static const char osd_name[] = "osd";
static const char *osd_version_string = "open-osd 0.2.0";

MODULE_AUTHOR("Boaz Harrosh <bharrosh@panasas.com>");
MODULE_DESCRIPTION("open-osd Upper-Layer-Driver osd.ko");
MODULE_LICENSE("GPL");
MODULE_ALIAS_CHARDEV_MAJOR(SCSI_OSD_MAJOR);
MODULE_ALIAS_SCSI_DEVICE(TYPE_OSD);

struct osd_uld_device {
        int minor;
        struct device class_dev;
        struct cdev cdev;
        struct osd_dev od;
        struct osd_dev_info odi;
        struct gendisk *disk;
};

struct osd_dev_handle {
        struct osd_dev od;
        struct file *file;
        struct osd_uld_device *oud;
} ;

static DEFINE_IDA(osd_minor_ida);

static struct class osd_uld_class = {
        .owner          = THIS_MODULE,
        .name           = "scsi_osd",
};

/*
 * Char Device operations
 */

static int osd_uld_open(struct inode *inode, struct file *file)
{
        struct osd_uld_device *oud = container_of(inode->i_cdev,
                                        struct osd_uld_device, cdev);

        get_device(&oud->class_dev);
        /* cache osd_uld_device on file handle */
        file->private_data = oud;
        OSD_DEBUG("osd_uld_open %p\n", oud);
        return 0;
}

static int osd_uld_release(struct inode *inode, struct file *file)
{
        struct osd_uld_device *oud = file->private_data;

        OSD_DEBUG("osd_uld_release %p\n", file->private_data);
        file->private_data = NULL;
        put_device(&oud->class_dev);
        return 0;
}

/* FIXME: Only one vector for now */
unsigned g_test_ioctl;
do_test_fn *g_do_test;

int osduld_register_test(unsigned ioctl, do_test_fn *do_test)
{
        if (g_test_ioctl)
                return -EINVAL;

        g_test_ioctl = ioctl;
        g_do_test = do_test;
        return 0;
}
EXPORT_SYMBOL(osduld_register_test);

void osduld_unregister_test(unsigned ioctl)
{
        if (ioctl == g_test_ioctl) {
                g_test_ioctl = 0;
                g_do_test = NULL;
        }
}
EXPORT_SYMBOL(osduld_unregister_test);

static do_test_fn *_find_ioctl(unsigned cmd)
{
        if (g_test_ioctl == cmd)
                return g_do_test;
        else
                return NULL;
}

static long osd_uld_ioctl(struct file *file, unsigned int cmd,
        unsigned long arg)
{
        struct osd_uld_device *oud = file->private_data;
        int ret;
        do_test_fn *do_test;

        do_test = _find_ioctl(cmd);
        if (do_test)
                ret = do_test(&oud->od, cmd, arg);
        else {
                OSD_ERR("Unknown ioctl %d: osd_uld_device=%p\n", cmd, oud);
                ret = -ENOIOCTLCMD;
        }
        return ret;
}

static const struct file_operations osd_fops = {
        .owner          = THIS_MODULE,
        .open           = osd_uld_open,
        .release        = osd_uld_release,
        .unlocked_ioctl = osd_uld_ioctl,
        .llseek         = noop_llseek,
};

struct osd_dev *osduld_path_lookup(const char *name)
{
        struct osd_uld_device *oud;
        struct osd_dev_handle *odh;
        struct file *file;
        int error;

        if (!name || !*name) {
                OSD_ERR("Mount with !path || !*path\n");
                return ERR_PTR(-EINVAL);
        }

        odh = kzalloc(sizeof(*odh), GFP_KERNEL);
        if (unlikely(!odh))
                return ERR_PTR(-ENOMEM);

        file = filp_open(name, O_RDWR, 0);
        if (IS_ERR(file)) {
                error = PTR_ERR(file);
                goto free_od;
        }

        if (file->f_op != &osd_fops){
                error = -EINVAL;
                goto close_file;
        }

        oud = file->private_data;

        odh->od = oud->od;
        odh->file = file;
        odh->oud = oud;

        return &odh->od;

close_file:
        fput(file);
free_od:
        kfree(odh);
        return ERR_PTR(error);
}
EXPORT_SYMBOL(osduld_path_lookup);

static inline bool _the_same_or_null(const u8 *a1, unsigned a1_len,
                                     const u8 *a2, unsigned a2_len)
{
        if (!a2_len) /* User string is Empty means don't care */
                return true;

        if (a1_len != a2_len)
                return false;

        return 0 == memcmp(a1, a2, a1_len);
}

struct find_oud_t {
        const struct osd_dev_info *odi;
        struct device *dev;
        struct osd_uld_device *oud;
} ;

int _mach_odi(struct device *dev, void *find_data)
{
        struct osd_uld_device *oud = container_of(dev, struct osd_uld_device,
                                                  class_dev);
        struct find_oud_t *fot = find_data;
        const struct osd_dev_info *odi = fot->odi;

        if (_the_same_or_null(oud->odi.systemid, oud->odi.systemid_len,
                              odi->systemid, odi->systemid_len) &&
            _the_same_or_null(oud->odi.osdname, oud->odi.osdname_len,
                              odi->osdname, odi->osdname_len)) {
                OSD_DEBUG("found device sysid_len=%d osdname=%d\n",
                          odi->systemid_len, odi->osdname_len);
                fot->oud = oud;
                return 1;
        } else {
                return 0;
        }
}

/* osduld_info_lookup - Loop through all devices, return the requested osd_dev.
 *
 * if @odi->systemid_len and/or @odi->osdname_len are zero, they act as a don't
 * care. .e.g if they're both zero /dev/osd0 is returned.
 */
struct osd_dev *osduld_info_lookup(const struct osd_dev_info *odi)
{
        struct find_oud_t find = {.odi = odi};

        find.dev = class_find_device(&osd_uld_class, NULL, &find, _mach_odi);
        if (likely(find.dev)) {
                struct osd_dev_handle *odh = kzalloc(sizeof(*odh), GFP_KERNEL);

                if (unlikely(!odh)) {
                        put_device(find.dev);
                        return ERR_PTR(-ENOMEM);
                }

                odh->od = find.oud->od;
                odh->oud = find.oud;

                return &odh->od;
        }

        return ERR_PTR(-ENODEV);
}
EXPORT_SYMBOL(osduld_info_lookup);

void osduld_put_device(struct osd_dev *od)
{
        if (od && !IS_ERR(od)) {
                struct osd_dev_handle *odh =
                                container_of(od, struct osd_dev_handle, od);
                struct osd_uld_device *oud = odh->oud;

                BUG_ON(od->scsi_device != oud->od.scsi_device);

                /* If scsi has released the device (logout), and exofs has last
                 * reference on oud it will be freed by above osd_uld_release
                 * within fput below. But this will oops in cdev_release which
                 * is called after the fops->release. A get_/put_ pair makes
                 * sure we have a cdev for the duration of fput
                 */
                if (odh->file) {
                        get_device(&oud->class_dev);
                        fput(odh->file);
                }
                put_device(&oud->class_dev);
                kfree(odh);
        }
}
EXPORT_SYMBOL(osduld_put_device);

const struct osd_dev_info *osduld_device_info(struct osd_dev *od)
{
        struct osd_dev_handle *odh =
                                container_of(od, struct osd_dev_handle, od);
        return &odh->oud->odi;
}
EXPORT_SYMBOL(osduld_device_info);

bool osduld_device_same(struct osd_dev *od, const struct osd_dev_info *odi)
{
        struct osd_dev_handle *odh =
                                container_of(od, struct osd_dev_handle, od);
        struct osd_uld_device *oud = odh->oud;

        return (oud->odi.systemid_len == odi->systemid_len) &&
                _the_same_or_null(oud->odi.systemid, oud->odi.systemid_len,
                                 odi->systemid, odi->systemid_len) &&
                (oud->odi.osdname_len == odi->osdname_len) &&
                _the_same_or_null(oud->odi.osdname, oud->odi.osdname_len,
                                  odi->osdname, odi->osdname_len);
}
EXPORT_SYMBOL(osduld_device_same);

/*
 * Scsi Device operations
 */

static int __detect_osd(struct osd_uld_device *oud)
{
        struct scsi_device *scsi_device = oud->od.scsi_device;
        char caps[OSD_CAP_LEN];
        int error;

        /* sending a test_unit_ready as first command seems to be needed
         * by some targets
         */
        OSD_DEBUG("start scsi_test_unit_ready %p %p %p\n",
                        oud, scsi_device, scsi_device->request_queue);
        error = scsi_test_unit_ready(scsi_device, 10*HZ, 5, NULL);
        if (error)
                OSD_ERR("warning: scsi_test_unit_ready failed\n");

        osd_sec_init_nosec_doall_caps(caps, &osd_root_object, false, true);
        if (osd_auto_detect_ver(&oud->od, caps, &oud->odi))
                return -ENODEV;

        return 0;
}

static void __remove(struct device *dev)
{
        struct osd_uld_device *oud = container_of(dev, struct osd_uld_device,
                                                  class_dev);
        struct scsi_device *scsi_device = oud->od.scsi_device;

        kfree(oud->odi.osdname);

        if (oud->cdev.owner)
                cdev_del(&oud->cdev);

        osd_dev_fini(&oud->od);
        scsi_device_put(scsi_device);

        OSD_INFO("osd_remove %s\n",
                 oud->disk ? oud->disk->disk_name : NULL);

        if (oud->disk)
                put_disk(oud->disk);
        ida_remove(&osd_minor_ida, oud->minor);

        kfree(oud);
}

static int osd_probe(struct device *dev)
{
        struct scsi_device *scsi_device = to_scsi_device(dev);
        struct gendisk *disk;
        struct osd_uld_device *oud;
        int minor;
        int error;

        if (scsi_device->type != TYPE_OSD)
                return -ENODEV;

        do {
                if (!ida_pre_get(&osd_minor_ida, GFP_KERNEL))
                        return -ENODEV;

                error = ida_get_new(&osd_minor_ida, &minor);
        } while (error == -EAGAIN);

        if (error)
                return error;
        if (minor >= SCSI_OSD_MAX_MINOR) {
                error = -EBUSY;
                goto err_retract_minor;
        }

        error = -ENOMEM;
        oud = kzalloc(sizeof(*oud), GFP_KERNEL);
        if (NULL == oud)
                goto err_retract_minor;

        dev_set_drvdata(dev, oud);
        oud->minor = minor;

        /* allocate a disk and set it up */
        /* FIXME: do we need this since sg has already done that */
        disk = alloc_disk(1);
        if (!disk) {
                OSD_ERR("alloc_disk failed\n");
                goto err_free_osd;
        }
        disk->major = SCSI_OSD_MAJOR;
        disk->first_minor = oud->minor;
        sprintf(disk->disk_name, "osd%d", oud->minor);
        oud->disk = disk;

        /* hold one more reference to the scsi_device that will get released
         * in __release, in case a logout is happening while fs is mounted
         */
        scsi_device_get(scsi_device);
        osd_dev_init(&oud->od, scsi_device);

        /* Detect the OSD Version */
        error = __detect_osd(oud);
        if (error) {
                OSD_ERR("osd detection failed, non-compatible OSD device\n");
                goto err_put_disk;
        }

        /* init the char-device for communication with user-mode */
        cdev_init(&oud->cdev, &osd_fops);
        oud->cdev.owner = THIS_MODULE;
        error = cdev_add(&oud->cdev,
                         MKDEV(SCSI_OSD_MAJOR, oud->minor), 1);
        if (error) {
                OSD_ERR("cdev_add failed\n");
                goto err_put_disk;
        }

        /* class device member */
        oud->class_dev.devt = oud->cdev.dev;
        oud->class_dev.class = &osd_uld_class;
        oud->class_dev.parent = dev;
        oud->class_dev.release = __remove;
        error = dev_set_name(&oud->class_dev, disk->disk_name);
        if (error) {
                OSD_ERR("dev_set_name failed => %d\n", error);
                goto err_put_cdev;
        }

        error = device_register(&oud->class_dev);
        if (error) {
                OSD_ERR("device_register failed => %d\n", error);
                goto err_put_cdev;
        }

        get_device(&oud->class_dev);

        OSD_INFO("osd_probe %s\n", disk->disk_name);
        return 0;

err_put_cdev:
        cdev_del(&oud->cdev);
err_put_disk:
        scsi_device_put(scsi_device);
        put_disk(disk);
err_free_osd:
        dev_set_drvdata(dev, NULL);
        kfree(oud);
err_retract_minor:
        ida_remove(&osd_minor_ida, minor);
        return error;
}

static int osd_remove(struct device *dev)
{
        struct scsi_device *scsi_device = to_scsi_device(dev);
        struct osd_uld_device *oud = dev_get_drvdata(dev);

        if (!oud || (oud->od.scsi_device != scsi_device)) {
                OSD_ERR("Half cooked osd-device %p,%p || %p!=%p",
                        dev, oud, oud ? oud->od.scsi_device : NULL,
                        scsi_device);
        }

        device_unregister(&oud->class_dev);

        put_device(&oud->class_dev);
        return 0;
}

/*
 * Global driver and scsi registration
 */

static struct scsi_driver osd_driver = {
        .owner                  = THIS_MODULE,
        .gendrv = {
                .name           = osd_name,
                .probe          = osd_probe,
                .remove         = osd_remove,
        }
};

static int __init osd_uld_init(void)
{
        int err;

        err = class_register(&osd_uld_class);
        if (err) {
                OSD_ERR("Unable to register sysfs class => %d\n", err);
                return err;
        }

        err = register_chrdev_region(MKDEV(SCSI_OSD_MAJOR, 0),
                                     SCSI_OSD_MAX_MINOR, osd_name);
        if (err) {
                OSD_ERR("Unable to register major %d for osd ULD => %d\n",
                        SCSI_OSD_MAJOR, err);
                goto err_out;
        }

        err = scsi_register_driver(&osd_driver.gendrv);
        if (err) {
                OSD_ERR("scsi_register_driver failed => %d\n", err);
                goto err_out_chrdev;
        }

        OSD_INFO("LOADED %s\n", osd_version_string);
        return 0;

err_out_chrdev:
        unregister_chrdev_region(MKDEV(SCSI_OSD_MAJOR, 0), SCSI_OSD_MAX_MINOR);
err_out:
        class_unregister(&osd_uld_class);
        return err;
}

static void __exit osd_uld_exit(void)
{
        scsi_unregister_driver(&osd_driver.gendrv);
        unregister_chrdev_region(MKDEV(SCSI_OSD_MAJOR, 0), SCSI_OSD_MAX_MINOR);
        class_unregister(&osd_uld_class);
        OSD_INFO("UNLOADED %s\n", osd_version_string);
}

module_init(osd_uld_init);
module_exit(osd_uld_exit);