/*
 * 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/smp_lock.h>
#include <linux/string.h>
#include <linux/parser.h>
#include <linux/vfs.h>
#include <linux/random.h>
#include <linux/exportfs.h>

#include "exofs.h"

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

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

/*
 * exofs-specific mount-time options.
 */
enum { Opt_pid, Opt_to, Opt_mkfs, Opt_format, 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_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_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;
}

/*
 * Remove an inode from the cache
 */
static void exofs_destroy_inode(struct inode *inode)
{
        kmem_cache_free(exofs_inode_cachep, exofs_i(inode));
}

/*
 * 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);
}

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

/*
 * Write the superblock to the OSD
 */
int exofs_sync_fs(struct super_block *sb, int wait)
{
        struct exofs_sb_info *sbi;
        struct exofs_fscb *fscb;
        struct osd_request *or;
        struct osd_obj_id obj;
        int ret = -ENOMEM;

        fscb = kzalloc(sizeof(struct exofs_fscb), GFP_KERNEL);
        if (!fscb) {
                EXOFS_ERR("exofs_write_super: memory allocation failed.\n");
                return -ENOMEM;
        }

        lock_super(sb);
        sbi = sb->s_fs_info;
        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;

        or = osd_start_request(sbi->s_dev, GFP_KERNEL);
        if (unlikely(!or)) {
                EXOFS_ERR("exofs_write_super: osd_start_request failed.\n");
                goto out;
        }

        obj.partition = sbi->s_pid;
        obj.id = EXOFS_SUPER_ID;
        ret = osd_req_write_kern(or, &obj, 0, fscb, sizeof(*fscb));
        if (unlikely(ret)) {
                EXOFS_ERR("exofs_write_super: osd_req_write_kern failed.\n");
                goto out;
        }

        ret = exofs_sync_op(or, sbi->s_timeout, sbi->s_cred);
        if (unlikely(ret)) {
                EXOFS_ERR("exofs_write_super: exofs_sync_op failed.\n");
                goto out;
        }
        sb->s_dirt = 0;

out:
        if (or)
                osd_end_request(or);
        unlock_super(sb);
        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;
}

/*
 * 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;

        if (sb->s_dirt)
                exofs_write_super(sb);

        /* 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;
                init_waitqueue_head(&wq);
                wait_event_timeout(wq,
                                  (atomic_read(&sbi->s_curr_pending) == 0),
                                  msecs_to_jiffies(100));
        }

        osduld_put_device(sbi->s_dev);
        kfree(sb->s_fs_info);
        sb->s_fs_info = NULL;
}

/*
 * 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 exofs_fscb fscb;         /*on-disk superblock info        */
        struct osd_request *or = NULL;
        struct osd_obj_id obj;
        int ret;

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

        /* use mount options to fill superblock */
        sbi->s_dev = osduld_path_lookup(opts->dev_name);
        if (IS_ERR(sbi->s_dev)) {
                ret = PTR_ERR(sbi->s_dev);
                sbi->s_dev = NULL;
                goto free_sbi;
        }

        sbi->s_pid = opts->pid;
        sbi->s_timeout = opts->timeout;

        /* 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;

        /* read data from on-disk superblock object */
        obj.partition = sbi->s_pid;
        obj.id = EXOFS_SUPER_ID;
        exofs_make_credential(sbi->s_cred, &obj);

        or = osd_start_request(sbi->s_dev, GFP_KERNEL);
        if (unlikely(!or)) {
                if (!silent)
                        EXOFS_ERR(
                               "exofs_fill_super: osd_start_request failed.\n");
                ret = -ENOMEM;
                goto free_sbi;
        }
        ret = osd_req_read_kern(or, &obj, 0, &fscb, sizeof(fscb));
        if (unlikely(ret)) {
                if (!silent)
                        EXOFS_ERR(
                               "exofs_fill_super: osd_req_read_kern failed.\n");
                ret = -ENOMEM;
                goto free_sbi;
        }

        ret = exofs_sync_op(or, sbi->s_timeout, sbi->s_cred);
        if (unlikely(ret)) {
                if (!silent)
                        EXOFS_ERR("exofs_fill_super: exofs_sync_op failed.\n");
                ret = -EIO;
                goto free_sbi;
        }

        sb->s_magic = le16_to_cpu(fscb.s_magic);
        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;
        }

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

        /* set up operation vectors */
        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 = 0;
out:
        if (or)
                osd_end_request(or);
        return ret;

free_sbi:
        osduld_put_device(sbi->s_dev); /* NULL safe */
        kfree(sbi);
        goto out;
}

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

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

        opts.dev_name = dev_name;
        return get_sb_nodev(type, flags, &opts, exofs_fill_super, mnt);
}

/*
 * 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 osd_obj_id obj = {sbi->s_pid, 0};
        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;
        struct osd_request *or;
        uint8_t cred_a[OSD_CAP_LEN];
        int ret;

        /* get used/capacity attributes */
        exofs_make_credential(cred_a, &obj);

        or = osd_start_request(sbi->s_dev, GFP_KERNEL);
        if (unlikely(!or)) {
                EXOFS_DBGMSG("exofs_statfs: osd_start_request failed.\n");
                return -ENOMEM;
        }

        osd_req_get_attributes(or, &obj);
        osd_req_add_get_attr_list(or, attrs, ARRAY_SIZE(attrs));
        ret = exofs_sync_op(or, sbi->s_timeout, cred_a);
        if (unlikely(ret))
                goto out;

        ret = extract_attr_from_req(or, &attrs[0]);
        if (likely(!ret))
                capacity = get_unaligned_be64(attrs[0].val_ptr);
        else
                EXOFS_DBGMSG("exofs_statfs: get capacity failed.\n");

        ret = extract_attr_from_req(or, &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 >> EXOFS_BLKSHIFT);
        buf->f_bfree = ((capacity - used) >> EXOFS_BLKSHIFT);
        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:
        osd_end_request(or);
        return ret;
}

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

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

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

        if (!ino)
                return NULL;

        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",
        .get_sb         = exofs_get_sb,
        .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)