// SPDX-License-Identifier: GPL-2.0
/*
 * Super block/filesystem wide operations
 *
 * Copyright (C) 1996 Peter J. Braam <braam@maths.ox.ac.uk> and 
 * Michael Callahan <callahan@maths.ox.ac.uk> 
 * 
 * Rewritten for Linux 2.1.  Peter Braam <braam@cs.cmu.edu>
 * Copyright (C) Carnegie Mellon University
 */

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/string.h>
#include <linux/stat.h>
#include <linux/errno.h>
#include <linux/unistd.h>
#include <linux/mutex.h>
#include <linux/spinlock.h>
#include <linux/file.h>
#include <linux/vfs.h>
#include <linux/slab.h>
#include <linux/pid_namespace.h>
#include <linux/uaccess.h>
#include <linux/fs.h>
#include <linux/fs_context.h>
#include <linux/fs_parser.h>
#include <linux/vmalloc.h>

#include <linux/coda.h>
#include "coda_psdev.h"
#include "coda_linux.h"
#include "coda_cache.h"

#include "coda_int.h"

/* VFS super_block ops */
static void coda_evict_inode(struct inode *);
static void coda_put_super(struct super_block *);
static int coda_statfs(struct dentry *dentry, struct kstatfs *buf);

static struct kmem_cache * coda_inode_cachep;

static struct inode *coda_alloc_inode(struct super_block *sb)
{
        struct coda_inode_info *ei;
        ei = alloc_inode_sb(sb, coda_inode_cachep, GFP_KERNEL);
        if (!ei)
                return NULL;
        memset(&ei->c_fid, 0, sizeof(struct CodaFid));
        ei->c_flags = 0;
        ei->c_uid = GLOBAL_ROOT_UID;
        ei->c_cached_perm = 0;
        spin_lock_init(&ei->c_lock);
        return &ei->vfs_inode;
}

static void coda_free_inode(struct inode *inode)
{
        kmem_cache_free(coda_inode_cachep, ITOC(inode));
}

static void init_once(void *foo)
{
        struct coda_inode_info *ei = (struct coda_inode_info *) foo;

        inode_init_once(&ei->vfs_inode);
}

int __init coda_init_inodecache(void)
{
        coda_inode_cachep = kmem_cache_create("coda_inode_cache",
                                sizeof(struct coda_inode_info), 0,
                                SLAB_RECLAIM_ACCOUNT | SLAB_ACCOUNT,
                                init_once);
        if (coda_inode_cachep == NULL)
                return -ENOMEM;
        return 0;
}

void coda_destroy_inodecache(void)
{
        /*
         * Make sure all delayed rcu free inodes are flushed before we
         * destroy cache.
         */
        rcu_barrier();
        kmem_cache_destroy(coda_inode_cachep);
}

static int coda_reconfigure(struct fs_context *fc)
{
        sync_filesystem(fc->root->d_sb);
        fc->sb_flags |= SB_NOATIME;
        return 0;
}

/* exported operations */
static const struct super_operations coda_super_operations =
{
        .alloc_inode    = coda_alloc_inode,
        .free_inode     = coda_free_inode,
        .evict_inode    = coda_evict_inode,
        .put_super      = coda_put_super,
        .statfs         = coda_statfs,
};

struct coda_fs_context {
        int     idx;
};

enum {
        Opt_fd,
};

static const struct fs_parameter_spec coda_param_specs[] = {
        fsparam_fd      ("fd",  Opt_fd),
        {}
};

static int coda_set_idx(struct fs_context *fc, struct file *file)
{
        struct coda_fs_context *ctx = fc->fs_private;
        struct inode *inode;
        int idx;

        inode = file_inode(file);
        if (!S_ISCHR(inode->i_mode) || imajor(inode) != CODA_PSDEV_MAJOR) {
                return invalf(fc, "coda: Not coda psdev");
        }
        idx = iminor(inode);
        if (idx < 0 || idx >= MAX_CODADEVS)
                return invalf(fc, "coda: Bad minor number");
        ctx->idx = idx;
        return 0;
}

static int coda_parse_fd(struct fs_context *fc, struct fs_parameter *param,
                         struct fs_parse_result *result)
{
        struct file *file;
        int err;

        if (param->type == fs_value_is_file) {
                file = param->file;
                param->file = NULL;
        } else {
                file = fget(result->uint_32);
        }
        if (!file)
                return -EBADF;

        err = coda_set_idx(fc, file);
        fput(file);
        return err;
}

static int coda_parse_param(struct fs_context *fc, struct fs_parameter *param)
{
        struct fs_parse_result result;
        int opt;

        opt = fs_parse(fc, coda_param_specs, param, &result);
        if (opt < 0)
                return opt;

        switch (opt) {
        case Opt_fd:
                return coda_parse_fd(fc, param, &result);
        }

        return 0;
}

/*
 * Parse coda's binary mount data form.  We ignore any errors and go with index
 * 0 if we get one for backward compatibility.
 */
static int coda_parse_monolithic(struct fs_context *fc, void *_data)
{
        struct file *file;
        struct coda_mount_data *data = _data;

        if (!data)
                return invalf(fc, "coda: Bad mount data");

        if (data->version != CODA_MOUNT_VERSION)
                return invalf(fc, "coda: Bad mount version");

        file = fget(data->fd);
        if (file) {
                coda_set_idx(fc, file);
                fput(file);
        }
        return 0;
}

static int coda_fill_super(struct super_block *sb, struct fs_context *fc)
{
        struct coda_fs_context *ctx = fc->fs_private;
        struct inode *root = NULL;
        struct venus_comm *vc;
        struct CodaFid fid;
        int error;

        infof(fc, "coda: device index: %i\n", ctx->idx);

        vc = &coda_comms[ctx->idx];
        mutex_lock(&vc->vc_mutex);

        if (!vc->vc_inuse) {
                errorf(fc, "coda: No pseudo device");
                error = -EINVAL;
                goto unlock_out;
        }

        if (vc->vc_sb) {
                errorf(fc, "coda: Device already mounted");
                error = -EBUSY;
                goto unlock_out;
        }

        vc->vc_sb = sb;
        mutex_unlock(&vc->vc_mutex);

        sb->s_fs_info = vc;
        sb->s_flags |= SB_NOATIME;
        sb->s_blocksize = 4096; /* XXXXX  what do we put here?? */
        sb->s_blocksize_bits = 12;
        sb->s_magic = CODA_SUPER_MAGIC;
        sb->s_op = &coda_super_operations;
        set_default_d_op(sb, &coda_dentry_operations);
        sb->s_time_gran = 1;
        sb->s_time_min = S64_MIN;
        sb->s_time_max = S64_MAX;

        error = super_setup_bdi(sb);
        if (error)
                goto error;

        /* get root fid from Venus: this needs the root inode */
        error = venus_rootfid(sb, &fid);
        if ( error ) {
                pr_warn("%s: coda_get_rootfid failed with %d\n",
                        __func__, error);
                goto error;
        }
        pr_info("%s: rootfid is %s\n", __func__, coda_f2s(&fid));
        
        /* make root inode */
        root = coda_cnode_make(&fid, sb);
        if (IS_ERR(root)) {
                error = PTR_ERR(root);
                pr_warn("Failure of coda_cnode_make for root: error %d\n",
                        error);
                goto error;
        } 

        pr_info("%s: rootinode is %ld dev %s\n",
                __func__, root->i_ino, root->i_sb->s_id);
        sb->s_root = d_make_root(root);
        if (!sb->s_root) {
                error = -EINVAL;
                goto error;
        }
        return 0;

error:
        mutex_lock(&vc->vc_mutex);
        vc->vc_sb = NULL;
        sb->s_fs_info = NULL;
unlock_out:
        mutex_unlock(&vc->vc_mutex);
        return error;
}

static void coda_put_super(struct super_block *sb)
{
        struct venus_comm *vcp = coda_vcp(sb);
        mutex_lock(&vcp->vc_mutex);
        vcp->vc_sb = NULL;
        sb->s_fs_info = NULL;
        mutex_unlock(&vcp->vc_mutex);
        mutex_destroy(&vcp->vc_mutex);

        pr_info("Bye bye.\n");
}

static void coda_evict_inode(struct inode *inode)
{
        truncate_inode_pages_final(&inode->i_data);
        clear_inode(inode);
        coda_cache_clear_inode(inode);
}

int coda_getattr(struct mnt_idmap *idmap, const struct path *path,
                 struct kstat *stat, u32 request_mask, unsigned int flags)
{
        int err = coda_revalidate_inode(d_inode(path->dentry));
        if (!err)
                generic_fillattr(&nop_mnt_idmap, request_mask,
                                 d_inode(path->dentry), stat);
        return err;
}

int coda_setattr(struct mnt_idmap *idmap, struct dentry *de,
                 struct iattr *iattr)
{
        struct inode *inode = d_inode(de);
        struct coda_vattr vattr;
        int error;

        memset(&vattr, 0, sizeof(vattr)); 

        inode_set_ctime_current(inode);
        coda_iattr_to_vattr(iattr, &vattr);
        vattr.va_type = C_VNON; /* cannot set type */

        /* Venus is responsible for truncating the container-file!!! */
        error = venus_setattr(inode->i_sb, coda_i2f(inode), &vattr);

        if (!error) {
                coda_vattr_to_iattr(inode, &vattr); 
                coda_cache_clear_inode(inode);
        }
        return error;
}

const struct inode_operations coda_file_inode_operations = {
        .permission     = coda_permission,
        .getattr        = coda_getattr,
        .setattr        = coda_setattr,
};

static int coda_statfs(struct dentry *dentry, struct kstatfs *buf)
{
        int error;
        
        error = venus_statfs(dentry, buf);

        if (error) {
                /* fake something like AFS does */
                buf->f_blocks = 9000000;
                buf->f_bfree  = 9000000;
                buf->f_bavail = 9000000;
                buf->f_files  = 9000000;
                buf->f_ffree  = 9000000;
        }

        /* and fill in the rest */
        buf->f_type = CODA_SUPER_MAGIC;
        buf->f_bsize = 4096;
        buf->f_namelen = CODA_MAXNAMLEN;

        return 0; 
}

static int coda_get_tree(struct fs_context *fc)
{
        if (task_active_pid_ns(current) != &init_pid_ns)
                return -EINVAL;

        return get_tree_nodev(fc, coda_fill_super);
}

static void coda_free_fc(struct fs_context *fc)
{
        kfree(fc->fs_private);
}

static const struct fs_context_operations coda_context_ops = {
        .free           = coda_free_fc,
        .parse_param    = coda_parse_param,
        .parse_monolithic = coda_parse_monolithic,
        .get_tree       = coda_get_tree,
        .reconfigure    = coda_reconfigure,
};

static int coda_init_fs_context(struct fs_context *fc)
{
        struct coda_fs_context *ctx;

        ctx = kzalloc_obj(struct coda_fs_context);
        if (!ctx)
                return -ENOMEM;

        fc->fs_private = ctx;
        fc->ops = &coda_context_ops;
        return 0;
}

struct file_system_type coda_fs_type = {
        .owner          = THIS_MODULE,
        .name           = "coda",
        .init_fs_context = coda_init_fs_context,
        .parameters     = coda_param_specs,
        .kill_sb        = kill_anon_super,
        .fs_flags       = FS_BINARY_MOUNTDATA,
};
MODULE_ALIAS_FS("coda");