/*
 * Copyright (C) 2005, 2006
 * Avishay Traeger (avishay@gmail.com)
 * Copyright (C) 2008, 2009
 * Boaz Harrosh <bharrosh@panasas.com>
 *
 * Copyrights for code taken from ext2:
 *     Copyright (C) 1992, 1993, 1994, 1995
 *     Remy Card (card@masi.ibp.fr)
 *     Laboratoire MASI - Institut Blaise Pascal
 *     Universite Pierre et Marie Curie (Paris VI)
 *     from
 *     linux/fs/minix/inode.c
 *     Copyright (C) 1991, 1992  Linus Torvalds
 *
 * This file is part of exofs.
 *
 * exofs 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.  Since it is based on ext2, and the only
 * valid version of GPL for the Linux kernel is version 2, the only valid
 * version of GPL for exofs is version 2.
 *
 * exofs is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with exofs; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 */

#include <linux/string.h>
#include <linux/parser.h>
#include <linux/vfs.h>
#include <linux/random.h>
#include <linux/module.h>
#include <linux/exportfs.h>
#include <linux/slab.h>

#include "exofs.h"

#define EXOFS_DBGMSG2(M...) do {} while (0)

/******************************************************************************
 * MOUNT OPTIONS
 *****************************************************************************/

/*
 * struct to hold what we get from mount options
 */
struct exofs_mountopt {
        bool is_osdname;
        const char *dev_name;
        uint64_t pid;
        int timeout;
};

/*
 * exofs-specific mount-time options.
 */
enum { Opt_name, Opt_pid, Opt_to, Opt_err };

/*
 * Our mount-time options.  These should ideally be 64-bit unsigned, but the
 * kernel's parsing functions do not currently support that.  32-bit should be
 * sufficient for most applications now.
 */
static match_table_t tokens = {
        {Opt_name, "osdname=%s"},
        {Opt_pid, "pid=%u"},
        {Opt_to, "to=%u"},
        {Opt_err, NULL}
};

/*
 * The main option parsing method.  Also makes sure that all of the mandatory
 * mount options were set.
 */
static int parse_options(char *options, struct exofs_mountopt *opts)
{
        char *p;
        substring_t args[MAX_OPT_ARGS];
        int option;
        bool s_pid = false;

        EXOFS_DBGMSG("parse_options %s\n", options);
        /* defaults */
        memset(opts, 0, sizeof(*opts));
        opts->timeout = BLK_DEFAULT_SG_TIMEOUT;

        while ((p = strsep(&options, ",")) != NULL) {
                int token;
                char str[32];

                if (!*p)
                        continue;

                token = match_token(p, tokens, args);
                switch (token) {
                case Opt_name:
                        opts->dev_name = match_strdup(&args[0]);
                        if (unlikely(!opts->dev_name)) {
                                EXOFS_ERR("Error allocating dev_name");
                                return -ENOMEM;
                        }
                        opts->is_osdname = true;
                        break;
                case Opt_pid:
                        if (0 == match_strlcpy(str, &args[0], sizeof(str)))
                                return -EINVAL;
                        opts->pid = simple_strtoull(str, NULL, 0);
                        if (opts->pid < EXOFS_MIN_PID) {
                                EXOFS_ERR("Partition ID must be >= %u",
                                          EXOFS_MIN_PID);
                                return -EINVAL;
                        }
                        s_pid = 1;
                        break;
                case Opt_to:
                        if (match_int(&args[0], &option))
                                return -EINVAL;
                        if (option <= 0) {
                                EXOFS_ERR("Timout must be > 0");
                                return -EINVAL;
                        }
                        opts->timeout = option * HZ;
                        break;
                }
        }

        if (!s_pid) {
                EXOFS_ERR("Need to specify the following options:\n");
                EXOFS_ERR("    -o pid=pid_no_to_use\n");
                return -EINVAL;
        }

        return 0;
}

/******************************************************************************
 * INODE CACHE
 *****************************************************************************/

/*
 * Our inode cache.  Isn't it pretty?
 */
static struct kmem_cache *exofs_inode_cachep;

/*
 * Allocate an inode in the cache
 */
static struct inode *exofs_alloc_inode(struct super_block *sb)
{
        struct exofs_i_info *oi;

        oi = kmem_cache_alloc(exofs_inode_cachep, GFP_KERNEL);
        if (!oi)
                return NULL;

        oi->vfs_inode.i_version = 1;
        return &oi->vfs_inode;
}

static void exofs_i_callback(struct rcu_head *head)
{
        struct inode *inode = container_of(head, struct inode, i_rcu);
        INIT_LIST_HEAD(&inode->i_dentry);
        kmem_cache_free(exofs_inode_cachep, exofs_i(inode));
}

/*
 * Remove an inode from the cache
 */
static void exofs_destroy_inode(struct inode *inode)
{
        call_rcu(&inode->i_rcu, exofs_i_callback);
}

/*
 * Initialize the inode
 */
static void exofs_init_once(void *foo)
{
        struct exofs_i_info *oi = foo;

        inode_init_once(&oi->vfs_inode);
}

/*
 * Create and initialize the inode cache
 */
static int init_inodecache(void)
{
        exofs_inode_cachep = kmem_cache_create("exofs_inode_cache",
                                sizeof(struct exofs_i_info), 0,
                                SLAB_RECLAIM_ACCOUNT | SLAB_MEM_SPREAD,
                                exofs_init_once);
        if (exofs_inode_cachep == NULL)
                return -ENOMEM;
        return 0;
}

/*
 * Destroy the inode cache
 */
static void destroy_inodecache(void)
{
        kmem_cache_destroy(exofs_inode_cachep);
}

/******************************************************************************
 * Some osd helpers
 *****************************************************************************/
void exofs_make_credential(u8 cred_a[OSD_CAP_LEN], const struct osd_obj_id *obj)
{
        osd_sec_init_nosec_doall_caps(cred_a, obj, false, true);
}

static int exofs_read_kern(struct osd_dev *od, u8 *cred, struct osd_obj_id *obj,
                    u64 offset, void *p, unsigned length)
{
        struct osd_request *or = osd_start_request(od, GFP_KERNEL);
/*      struct osd_sense_info osi = {.key = 0};*/
        int ret;

        if (unlikely(!or)) {
                EXOFS_DBGMSG("%s: osd_start_request failed.\n", __func__);
                return -ENOMEM;
        }
        ret = osd_req_read_kern(or, obj, offset, p, length);
        if (unlikely(ret)) {
                EXOFS_DBGMSG("%s: osd_req_read_kern failed.\n", __func__);
                goto out;
        }

        ret = osd_finalize_request(or, 0, cred, NULL);
        if (unlikely(ret)) {
                EXOFS_DBGMSG("Failed to osd_finalize_request() => %d\n", ret);
                goto out;
        }

        ret = osd_execute_request(or);
        if (unlikely(ret))
                EXOFS_DBGMSG("osd_execute_request() => %d\n", ret);
        /* osd_req_decode_sense(or, ret); */

out:
        osd_end_request(or);
        EXOFS_DBGMSG2("read_kern(0x%llx) offset=0x%llx "
                      "length=0x%llx dev=%p ret=>%d\n",
                      _LLU(obj->id), _LLU(offset), _LLU(length), od, ret);
        return ret;
}

static const struct osd_attr g_attr_sb_stats = ATTR_DEF(
        EXOFS_APAGE_SB_DATA,
        EXOFS_ATTR_SB_STATS,
        sizeof(struct exofs_sb_stats));

static int __sbi_read_stats(struct exofs_sb_info *sbi)
{
        struct osd_attr attrs[] = {
                [0] = g_attr_sb_stats,
        };
        struct ore_io_state *ios;
        int ret;

        ret = ore_get_io_state(&sbi->layout, &sbi->oc, &ios);
        if (unlikely(ret)) {
                EXOFS_ERR("%s: ore_get_io_state failed.\n", __func__);
                return ret;
        }

        ios->in_attr = attrs;
        ios->in_attr_len = ARRAY_SIZE(attrs);

        ret = ore_read(ios);
        if (unlikely(ret)) {
                EXOFS_ERR("Error reading super_block stats => %d\n", ret);
                goto out;
        }

        ret = extract_attr_from_ios(ios, &attrs[0]);
        if (ret) {
                EXOFS_ERR("%s: extract_attr of sb_stats failed\n", __func__);
                goto out;
        }
        if (attrs[0].len) {
                struct exofs_sb_stats *ess;

                if (unlikely(attrs[0].len != sizeof(*ess))) {
                        EXOFS_ERR("%s: Wrong version of exofs_sb_stats "
                                  "size(%d) != expected(%zd)\n",
                                  __func__, attrs[0].len, sizeof(*ess));
                        goto out;
                }

                ess = attrs[0].val_ptr;
                sbi->s_nextid = le64_to_cpu(ess->s_nextid);
                sbi->s_numfiles = le32_to_cpu(ess->s_numfiles);
        }

out:
        ore_put_io_state(ios);
        return ret;
}

static void stats_done(struct ore_io_state *ios, void *p)
{
        ore_put_io_state(ios);
        /* Good thanks nothing to do anymore */
}

/* Asynchronously write the stats attribute */
int exofs_sbi_write_stats(struct exofs_sb_info *sbi)
{
        struct osd_attr attrs[] = {
                [0] = g_attr_sb_stats,
        };
        struct ore_io_state *ios;
        int ret;

        ret = ore_get_io_state(&sbi->layout, &sbi->oc, &ios);
        if (unlikely(ret)) {
                EXOFS_ERR("%s: ore_get_io_state failed.\n", __func__);
                return ret;
        }

        sbi->s_ess.s_nextid   = cpu_to_le64(sbi->s_nextid);
        sbi->s_ess.s_numfiles = cpu_to_le64(sbi->s_numfiles);
        attrs[0].val_ptr = &sbi->s_ess;


        ios->done = stats_done;
        ios->private = sbi;
        ios->out_attr = attrs;
        ios->out_attr_len = ARRAY_SIZE(attrs);

        ret = ore_write(ios);
        if (unlikely(ret)) {
                EXOFS_ERR("%s: ore_write failed.\n", __func__);
                ore_put_io_state(ios);
        }

        return ret;
}

/******************************************************************************
 * SUPERBLOCK FUNCTIONS
 *****************************************************************************/
static const struct super_operations exofs_sops;
static const struct export_operations exofs_export_ops;

/*
 * Write the superblock to the OSD
 */
static int exofs_sync_fs(struct super_block *sb, int wait)
{
        struct exofs_sb_info *sbi;
        struct exofs_fscb *fscb;
        struct ore_comp one_comp;
        struct ore_components oc;
        struct ore_io_state *ios;
        int ret = -ENOMEM;

        fscb = kmalloc(sizeof(*fscb), GFP_KERNEL);
        if (unlikely(!fscb))
                return -ENOMEM;

        sbi = sb->s_fs_info;

        /* NOTE: We no longer dirty the super_block anywhere in exofs. The
         * reason we write the fscb here on unmount is so we can stay backwards
         * compatible with fscb->s_version == 1. (What we are not compatible
         * with is if a new version FS crashed and then we try to mount an old
         * version). Otherwise the exofs_fscb is read-only from mkfs time. All
         * the writeable info is set in exofs_sbi_write_stats() above.
         */

        exofs_init_comps(&oc, &one_comp, sbi, EXOFS_SUPER_ID);

        ret = ore_get_io_state(&sbi->layout, &oc, &ios);
        if (unlikely(ret))
                goto out;

        lock_super(sb);

        ios->length = offsetof(struct exofs_fscb, s_dev_table_oid);
        memset(fscb, 0, ios->length);
        fscb->s_nextid = cpu_to_le64(sbi->s_nextid);
        fscb->s_numfiles = cpu_to_le32(sbi->s_numfiles);
        fscb->s_magic = cpu_to_le16(sb->s_magic);
        fscb->s_newfs = 0;
        fscb->s_version = EXOFS_FSCB_VER;

        ios->offset = 0;
        ios->kern_buff = fscb;

        ret = ore_write(ios);
        if (unlikely(ret))
                EXOFS_ERR("%s: ore_write failed.\n", __func__);
        else
                sb->s_dirt = 0;


        unlock_super(sb);
out:
        EXOFS_DBGMSG("s_nextid=0x%llx ret=%d\n", _LLU(sbi->s_nextid), ret);
        ore_put_io_state(ios);
        kfree(fscb);
        return ret;
}

static void exofs_write_super(struct super_block *sb)
{
        if (!(sb->s_flags & MS_RDONLY))
                exofs_sync_fs(sb, 1);
        else
                sb->s_dirt = 0;
}

static void _exofs_print_device(const char *msg, const char *dev_path,
                                struct osd_dev *od, u64 pid)
{
        const struct osd_dev_info *odi = osduld_device_info(od);

        printk(KERN_NOTICE "exofs: %s %s osd_name-%s pid-0x%llx\n",
                msg, dev_path ?: "", odi->osdname, _LLU(pid));
}

static void exofs_free_sbi(struct exofs_sb_info *sbi)
{
        unsigned numdevs = sbi->oc.numdevs;

        while (numdevs) {
                unsigned i = --numdevs;
                struct osd_dev *od = ore_comp_dev(&sbi->oc, i);

                if (od) {
                        ore_comp_set_dev(&sbi->oc, i, NULL);
                        osduld_put_device(od);
                }
        }
        kfree(sbi->oc.ods);
        kfree(sbi);
}

/*
 * This function is called when the vfs is freeing the superblock.  We just
 * need to free our own part.
 */
static void exofs_put_super(struct super_block *sb)
{
        int num_pend;
        struct exofs_sb_info *sbi = sb->s_fs_info;

        /* make sure there are no pending commands */
        for (num_pend = atomic_read(&sbi->s_curr_pending); num_pend > 0;
             num_pend = atomic_read(&sbi->s_curr_pending)) {
                wait_queue_head_t wq;

                printk(KERN_NOTICE "%s: !!Pending operations in flight. "
                       "This is a BUG. please report to osd-dev@open-osd.org\n",
                       __func__);
                init_waitqueue_head(&wq);
                wait_event_timeout(wq,
                                  (atomic_read(&sbi->s_curr_pending) == 0),
                                  msecs_to_jiffies(100));
        }

        _exofs_print_device("Unmounting", NULL, ore_comp_dev(&sbi->oc, 0),
                            sbi->one_comp.obj.partition);

        bdi_destroy(&sbi->bdi);
        exofs_free_sbi(sbi);
        sb->s_fs_info = NULL;
}

static int _read_and_match_data_map(struct exofs_sb_info *sbi, unsigned numdevs,
                                    struct exofs_device_table *dt)
{
        int ret;

        sbi->layout.stripe_unit =
                                le64_to_cpu(dt->dt_data_map.cb_stripe_unit);
        sbi->layout.group_width =
                                le32_to_cpu(dt->dt_data_map.cb_group_width);
        sbi->layout.group_depth =
                                le32_to_cpu(dt->dt_data_map.cb_group_depth);
        sbi->layout.mirrors_p1  =
                                le32_to_cpu(dt->dt_data_map.cb_mirror_cnt) + 1;
        sbi->layout.raid_algorithm  =
                                le32_to_cpu(dt->dt_data_map.cb_raid_algorithm);

        ret = ore_verify_layout(numdevs, &sbi->layout);

        EXOFS_DBGMSG("exofs: layout: "
                "num_comps=%u stripe_unit=0x%x group_width=%u "
                "group_depth=0x%llx mirrors_p1=%u raid_algorithm=%u\n",
                numdevs,
                sbi->layout.stripe_unit,
                sbi->layout.group_width,
                _LLU(sbi->layout.group_depth),
                sbi->layout.mirrors_p1,
                sbi->layout.raid_algorithm);
        return ret;
}

static unsigned __ra_pages(struct ore_layout *layout)
{
        const unsigned _MIN_RA = 32; /* min 128K read-ahead */
        unsigned ra_pages = layout->group_width * layout->stripe_unit /
                                PAGE_SIZE;
        unsigned max_io_pages = exofs_max_io_pages(layout, ~0);

        ra_pages *= 2; /* two stripes */
        if (ra_pages < _MIN_RA)
                ra_pages = roundup(_MIN_RA, ra_pages / 2);

        if (ra_pages > max_io_pages)
                ra_pages = max_io_pages;

        return ra_pages;
}

/* @odi is valid only as long as @fscb_dev is valid */
static int exofs_devs_2_odi(struct exofs_dt_device_info *dt_dev,
                             struct osd_dev_info *odi)
{
        odi->systemid_len = le32_to_cpu(dt_dev->systemid_len);
        memcpy(odi->systemid, dt_dev->systemid, odi->systemid_len);

        odi->osdname_len = le32_to_cpu(dt_dev->osdname_len);
        odi->osdname = dt_dev->osdname;

        /* FIXME support long names. Will need a _put function */
        if (dt_dev->long_name_offset)
                return -EINVAL;

        /* Make sure osdname is printable!
         * mkexofs should give us space for a null-terminator else the
         * device-table is invalid.
         */
        if (unlikely(odi->osdname_len >= sizeof(dt_dev->osdname)))
                odi->osdname_len = sizeof(dt_dev->osdname) - 1;
        dt_dev->osdname[odi->osdname_len] = 0;

        /* If it's all zeros something is bad we read past end-of-obj */
        return !(odi->systemid_len || odi->osdname_len);
}

int __alloc_dev_table(struct exofs_sb_info *sbi, unsigned numdevs,
                      struct exofs_dev **peds)
{
        struct __alloc_ore_devs_and_exofs_devs {
                /* Twice bigger table: See exofs_init_comps() and comment at
                 * exofs_read_lookup_dev_table()
                 */
                struct ore_dev *oreds[numdevs * 2 - 1];
                struct exofs_dev eds[numdevs];
        } *aoded;
        struct exofs_dev *eds;
        unsigned i;

        aoded = kzalloc(sizeof(*aoded), GFP_KERNEL);
        if (unlikely(!aoded)) {
                EXOFS_ERR("ERROR: faild allocating Device array[%d]\n",
                          numdevs);
                return -ENOMEM;
        }

        sbi->oc.ods = aoded->oreds;
        *peds = eds = aoded->eds;
        for (i = 0; i < numdevs; ++i)
                aoded->oreds[i] = &eds[i].ored;
        return 0;
}

static int exofs_read_lookup_dev_table(struct exofs_sb_info *sbi,
                                       struct osd_dev *fscb_od,
                                       unsigned table_count)
{
        struct ore_comp comp;
        struct exofs_device_table *dt;
        struct exofs_dev *eds;
        unsigned table_bytes = table_count * sizeof(dt->dt_dev_table[0]) +
                                             sizeof(*dt);
        unsigned numdevs, i;
        int ret;

        dt = kmalloc(table_bytes, GFP_KERNEL);
        if (unlikely(!dt)) {
                EXOFS_ERR("ERROR: allocating %x bytes for device table\n",
                          table_bytes);
                return -ENOMEM;
        }

        sbi->oc.numdevs = 0;

        comp.obj.partition = sbi->one_comp.obj.partition;
        comp.obj.id = EXOFS_DEVTABLE_ID;
        exofs_make_credential(comp.cred, &comp.obj);

        ret = exofs_read_kern(fscb_od, comp.cred, &comp.obj, 0, dt,
                              table_bytes);
        if (unlikely(ret)) {
                EXOFS_ERR("ERROR: reading device table\n");
                goto out;
        }

        numdevs = le64_to_cpu(dt->dt_num_devices);
        if (unlikely(!numdevs)) {
                ret = -EINVAL;
                goto out;
        }
        WARN_ON(table_count != numdevs);

        ret = _read_and_match_data_map(sbi, numdevs, dt);
        if (unlikely(ret))
                goto out;

        ret = __alloc_dev_table(sbi, numdevs, &eds);
        if (unlikely(ret))
                goto out;
        /* exofs round-robins the device table view according to inode
         * number. We hold a: twice bigger table hence inodes can point
         * to any device and have a sequential view of the table
         * starting at this device. See exofs_init_comps()
         */
        memcpy(&sbi->oc.ods[numdevs], &sbi->oc.ods[0],
                (numdevs - 1) * sizeof(sbi->oc.ods[0]));

        for (i = 0; i < numdevs; i++) {
                struct exofs_fscb fscb;
                struct osd_dev_info odi;
                struct osd_dev *od;

                if (exofs_devs_2_odi(&dt->dt_dev_table[i], &odi)) {
                        EXOFS_ERR("ERROR: Read all-zeros device entry\n");
                        ret = -EINVAL;
                        goto out;
                }

                printk(KERN_NOTICE "Add device[%d]: osd_name-%s\n",
                       i, odi.osdname);

                /* the exofs id is currently the table index */
                eds[i].did = i;

                /* On all devices the device table is identical. The user can
                 * specify any one of the participating devices on the command
                 * line. We always keep them in device-table order.
                 */
                if (fscb_od && osduld_device_same(fscb_od, &odi)) {
                        eds[i].ored.od = fscb_od;
                        ++sbi->oc.numdevs;
                        fscb_od = NULL;
                        continue;
                }

                od = osduld_info_lookup(&odi);
                if (IS_ERR(od)) {
                        ret = PTR_ERR(od);
                        EXOFS_ERR("ERROR: device requested is not found "
                                  "osd_name-%s =>%d\n", odi.osdname, ret);
                        goto out;
                }

                eds[i].ored.od = od;
                ++sbi->oc.numdevs;

                /* Read the fscb of the other devices to make sure the FS
                 * partition is there.
                 */
                ret = exofs_read_kern(od, comp.cred, &comp.obj, 0, &fscb,
                                      sizeof(fscb));
                if (unlikely(ret)) {
                        EXOFS_ERR("ERROR: Malformed participating device "
                                  "error reading fscb osd_name-%s\n",
                                  odi.osdname);
                        goto out;
                }

                /* TODO: verify other information is correct and FS-uuid
                 *       matches. Benny what did you say about device table
                 *       generation and old devices?
                 */
        }

out:
        kfree(dt);
        if (unlikely(fscb_od && !ret)) {
                        EXOFS_ERR("ERROR: Bad device-table container device not present\n");
                        osduld_put_device(fscb_od);
                        return -EINVAL;
        }
        return ret;
}

/*
 * Read the superblock from the OSD and fill in the fields
 */
static int exofs_fill_super(struct super_block *sb, void *data, int silent)
{
        struct inode *root;
        struct exofs_mountopt *opts = data;
        struct exofs_sb_info *sbi;      /*extended info                  */
        struct osd_dev *od;             /* Master device                 */
        struct exofs_fscb fscb;         /*on-disk superblock info        */
        struct ore_comp comp;
        unsigned table_count;
        int ret;

        sbi = kzalloc(sizeof(*sbi), GFP_KERNEL);
        if (!sbi)
                return -ENOMEM;

        /* use mount options to fill superblock */
        if (opts->is_osdname) {
                struct osd_dev_info odi = {.systemid_len = 0};

                odi.osdname_len = strlen(opts->dev_name);
                odi.osdname = (u8 *)opts->dev_name;
                od = osduld_info_lookup(&odi);
                kfree(opts->dev_name);
                opts->dev_name = NULL;
        } else {
                od = osduld_path_lookup(opts->dev_name);
        }
        if (IS_ERR(od)) {
                ret = -EINVAL;
                goto free_sbi;
        }

        /* Default layout in case we do not have a device-table */
        sbi->layout.stripe_unit = PAGE_SIZE;
        sbi->layout.mirrors_p1 = 1;
        sbi->layout.group_width = 1;
        sbi->layout.group_depth = -1;
        sbi->layout.group_count = 1;
        sbi->s_timeout = opts->timeout;

        sbi->one_comp.obj.partition = opts->pid;
        sbi->one_comp.obj.id = 0;
        exofs_make_credential(sbi->one_comp.cred, &sbi->one_comp.obj);
        sbi->oc.numdevs = 1;
        sbi->oc.single_comp = EC_SINGLE_COMP;
        sbi->oc.comps = &sbi->one_comp;

        /* fill in some other data by hand */
        memset(sb->s_id, 0, sizeof(sb->s_id));
        strcpy(sb->s_id, "exofs");
        sb->s_blocksize = EXOFS_BLKSIZE;
        sb->s_blocksize_bits = EXOFS_BLKSHIFT;
        sb->s_maxbytes = MAX_LFS_FILESIZE;
        atomic_set(&sbi->s_curr_pending, 0);
        sb->s_bdev = NULL;
        sb->s_dev = 0;

        comp.obj.partition = sbi->one_comp.obj.partition;
        comp.obj.id = EXOFS_SUPER_ID;
        exofs_make_credential(comp.cred, &comp.obj);

        ret = exofs_read_kern(od, comp.cred, &comp.obj, 0, &fscb, sizeof(fscb));
        if (unlikely(ret))
                goto free_sbi;

        sb->s_magic = le16_to_cpu(fscb.s_magic);
        /* NOTE: we read below to be backward compatible with old versions */
        sbi->s_nextid = le64_to_cpu(fscb.s_nextid);
        sbi->s_numfiles = le32_to_cpu(fscb.s_numfiles);

        /* make sure what we read from the object store is correct */
        if (sb->s_magic != EXOFS_SUPER_MAGIC) {
                if (!silent)
                        EXOFS_ERR("ERROR: Bad magic value\n");
                ret = -EINVAL;
                goto free_sbi;
        }
        if (le32_to_cpu(fscb.s_version) > EXOFS_FSCB_VER) {
                EXOFS_ERR("ERROR: Bad FSCB version expected-%d got-%d\n",
                          EXOFS_FSCB_VER, le32_to_cpu(fscb.s_version));
                ret = -EINVAL;
                goto free_sbi;
        }

        /* start generation numbers from a random point */
        get_random_bytes(&sbi->s_next_generation, sizeof(u32));
        spin_lock_init(&sbi->s_next_gen_lock);

        table_count = le64_to_cpu(fscb.s_dev_table_count);
        if (table_count) {
                ret = exofs_read_lookup_dev_table(sbi, od, table_count);
                if (unlikely(ret))
                        goto free_sbi;
        } else {
                struct exofs_dev *eds;

                ret = __alloc_dev_table(sbi, 1, &eds);
                if (unlikely(ret))
                        goto free_sbi;

                ore_comp_set_dev(&sbi->oc, 0, od);
        }

        __sbi_read_stats(sbi);

        /* set up operation vectors */
        sbi->bdi.ra_pages = __ra_pages(&sbi->layout);
        sb->s_bdi = &sbi->bdi;
        sb->s_fs_info = sbi;
        sb->s_op = &exofs_sops;
        sb->s_export_op = &exofs_export_ops;
        root = exofs_iget(sb, EXOFS_ROOT_ID - EXOFS_OBJ_OFF);
        if (IS_ERR(root)) {
                EXOFS_ERR("ERROR: exofs_iget failed\n");
                ret = PTR_ERR(root);
                goto free_sbi;
        }
        sb->s_root = d_alloc_root(root);
        if (!sb->s_root) {
                iput(root);
                EXOFS_ERR("ERROR: get root inode failed\n");
                ret = -ENOMEM;
                goto free_sbi;
        }

        if (!S_ISDIR(root->i_mode)) {
                dput(sb->s_root);
                sb->s_root = NULL;
                EXOFS_ERR("ERROR: corrupt root inode (mode = %hd)\n",
                       root->i_mode);
                ret = -EINVAL;
                goto free_sbi;
        }

        ret = bdi_setup_and_register(&sbi->bdi, "exofs", BDI_CAP_MAP_COPY);
        if (ret) {
                EXOFS_DBGMSG("Failed to bdi_setup_and_register\n");
                goto free_sbi;
        }

        _exofs_print_device("Mounting", opts->dev_name,
                            ore_comp_dev(&sbi->oc, 0),
                            sbi->one_comp.obj.partition);
        return 0;

free_sbi:
        EXOFS_ERR("Unable to mount exofs on %s pid=0x%llx err=%d\n",
                  opts->dev_name, sbi->one_comp.obj.partition, ret);
        exofs_free_sbi(sbi);
        return ret;
}

/*
 * Set up the superblock (calls exofs_fill_super eventually)
 */
static struct dentry *exofs_mount(struct file_system_type *type,
                          int flags, const char *dev_name,
                          void *data)
{
        struct exofs_mountopt opts;
        int ret;

        ret = parse_options(data, &opts);
        if (ret)
                return ERR_PTR(ret);

        if (!opts.dev_name)
                opts.dev_name = dev_name;
        return mount_nodev(type, flags, &opts, exofs_fill_super);
}

/*
 * Return information about the file system state in the buffer.  This is used
 * by the 'df' command, for example.
 */
static int exofs_statfs(struct dentry *dentry, struct kstatfs *buf)
{
        struct super_block *sb = dentry->d_sb;
        struct exofs_sb_info *sbi = sb->s_fs_info;
        struct ore_io_state *ios;
        struct osd_attr attrs[] = {
                ATTR_DEF(OSD_APAGE_PARTITION_QUOTAS,
                        OSD_ATTR_PQ_CAPACITY_QUOTA, sizeof(__be64)),
                ATTR_DEF(OSD_APAGE_PARTITION_INFORMATION,
                        OSD_ATTR_PI_USED_CAPACITY, sizeof(__be64)),
        };
        uint64_t capacity = ULLONG_MAX;
        uint64_t used = ULLONG_MAX;
        int ret;

        ret = ore_get_io_state(&sbi->layout, &sbi->oc, &ios);
        if (ret) {
                EXOFS_DBGMSG("ore_get_io_state failed.\n");
                return ret;
        }

        ios->in_attr = attrs;
        ios->in_attr_len = ARRAY_SIZE(attrs);

        ret = ore_read(ios);
        if (unlikely(ret))
                goto out;

        ret = extract_attr_from_ios(ios, &attrs[0]);
        if (likely(!ret)) {
                capacity = get_unaligned_be64(attrs[0].val_ptr);
                if (unlikely(!capacity))
                        capacity = ULLONG_MAX;
        } else
                EXOFS_DBGMSG("exofs_statfs: get capacity failed.\n");

        ret = extract_attr_from_ios(ios, &attrs[1]);
        if (likely(!ret))
                used = get_unaligned_be64(attrs[1].val_ptr);
        else
                EXOFS_DBGMSG("exofs_statfs: get used-space failed.\n");

        /* fill in the stats buffer */
        buf->f_type = EXOFS_SUPER_MAGIC;
        buf->f_bsize = EXOFS_BLKSIZE;
        buf->f_blocks = capacity >> 9;
        buf->f_bfree = (capacity - used) >> 9;
        buf->f_bavail = buf->f_bfree;
        buf->f_files = sbi->s_numfiles;
        buf->f_ffree = EXOFS_MAX_ID - sbi->s_numfiles;
        buf->f_namelen = EXOFS_NAME_LEN;

out:
        ore_put_io_state(ios);
        return ret;
}

static const struct super_operations exofs_sops = {
        .alloc_inode    = exofs_alloc_inode,
        .destroy_inode  = exofs_destroy_inode,
        .write_inode    = exofs_write_inode,
        .evict_inode    = exofs_evict_inode,
        .put_super      = exofs_put_super,
        .write_super    = exofs_write_super,
        .sync_fs        = exofs_sync_fs,
        .statfs         = exofs_statfs,
};

/******************************************************************************
 * EXPORT OPERATIONS
 *****************************************************************************/

static struct dentry *exofs_get_parent(struct dentry *child)
{
        unsigned long ino = exofs_parent_ino(child);

        if (!ino)
                return ERR_PTR(-ESTALE);

        return d_obtain_alias(exofs_iget(child->d_inode->i_sb, ino));
}

static struct inode *exofs_nfs_get_inode(struct super_block *sb,
                u64 ino, u32 generation)
{
        struct inode *inode;

        inode = exofs_iget(sb, ino);
        if (IS_ERR(inode))
                return ERR_CAST(inode);
        if (generation && inode->i_generation != generation) {
                /* we didn't find the right inode.. */
                iput(inode);
                return ERR_PTR(-ESTALE);
        }
        return inode;
}

static struct dentry *exofs_fh_to_dentry(struct super_block *sb,
                                struct fid *fid, int fh_len, int fh_type)
{
        return generic_fh_to_dentry(sb, fid, fh_len, fh_type,
                                    exofs_nfs_get_inode);
}

static struct dentry *exofs_fh_to_parent(struct super_block *sb,
                                struct fid *fid, int fh_len, int fh_type)
{
        return generic_fh_to_parent(sb, fid, fh_len, fh_type,
                                    exofs_nfs_get_inode);
}

static const struct export_operations exofs_export_ops = {
        .fh_to_dentry = exofs_fh_to_dentry,
        .fh_to_parent = exofs_fh_to_parent,
        .get_parent = exofs_get_parent,
};

/******************************************************************************
 * INSMOD/RMMOD
 *****************************************************************************/

/*
 * struct that describes this file system
 */
static struct file_system_type exofs_type = {
        .owner          = THIS_MODULE,
        .name           = "exofs",
        .mount          = exofs_mount,
        .kill_sb        = generic_shutdown_super,
};

static int __init init_exofs(void)
{
        int err;

        err = init_inodecache();
        if (err)
                goto out;

        err = register_filesystem(&exofs_type);
        if (err)
                goto out_d;

        return 0;
out_d:
        destroy_inodecache();
out:
        return err;
}

static void __exit exit_exofs(void)
{
        unregister_filesystem(&exofs_type);
        destroy_inodecache();
}

MODULE_AUTHOR("Avishay Traeger <avishay@gmail.com>");
MODULE_DESCRIPTION("exofs");
MODULE_LICENSE("GPL");

module_init(init_exofs)
module_exit(exit_exofs)