// SPDX-License-Identifier: GPL-2.0-or-later

/*
 * SPU file system
 *
 * (C) Copyright IBM Deutschland Entwicklung GmbH 2005
 *
 * Author: Arnd Bergmann <arndb@de.ibm.com>
 */

#include <linux/file.h>
#include <linux/fs.h>
#include <linux/fs_context.h>
#include <linux/fs_parser.h>
#include <linux/fsnotify.h>
#include <linux/backing-dev.h>
#include <linux/init.h>
#include <linux/ioctl.h>
#include <linux/module.h>
#include <linux/mount.h>
#include <linux/namei.h>
#include <linux/pagemap.h>
#include <linux/poll.h>
#include <linux/of.h>
#include <linux/seq_file.h>
#include <linux/slab.h>

#include <asm/spu.h>
#include <asm/spu_priv1.h>
#include <linux/uaccess.h>

#include "spufs.h"

struct spufs_sb_info {
        bool debug;
};

static struct kmem_cache *spufs_inode_cache;
char *isolated_loader;
static int isolated_loader_size;

static struct spufs_sb_info *spufs_get_sb_info(struct super_block *sb)
{
        return sb->s_fs_info;
}

static struct inode *
spufs_alloc_inode(struct super_block *sb)
{
        struct spufs_inode_info *ei;

        ei = kmem_cache_alloc(spufs_inode_cache, GFP_KERNEL);
        if (!ei)
                return NULL;

        ei->i_gang = NULL;
        ei->i_ctx = NULL;
        ei->i_openers = 0;

        return &ei->vfs_inode;
}

static void spufs_free_inode(struct inode *inode)
{
        kmem_cache_free(spufs_inode_cache, SPUFS_I(inode));
}

static void
spufs_init_once(void *p)
{
        struct spufs_inode_info *ei = p;

        inode_init_once(&ei->vfs_inode);
}

static struct inode *
spufs_new_inode(struct super_block *sb, umode_t mode)
{
        struct inode *inode;

        inode = new_inode(sb);
        if (!inode)
                goto out;

        inode->i_ino = get_next_ino();
        inode->i_mode = mode;
        inode->i_uid = current_fsuid();
        inode->i_gid = current_fsgid();
        simple_inode_init_ts(inode);
out:
        return inode;
}

static int
spufs_setattr(struct mnt_idmap *idmap, struct dentry *dentry,
              struct iattr *attr)
{
        struct inode *inode = d_inode(dentry);

        if ((attr->ia_valid & ATTR_SIZE) &&
            (attr->ia_size != inode->i_size))
                return -EINVAL;
        setattr_copy(&nop_mnt_idmap, inode, attr);
        mark_inode_dirty(inode);
        return 0;
}


static int
spufs_new_file(struct super_block *sb, struct dentry *dentry,
                const struct file_operations *fops, umode_t mode,
                size_t size, struct spu_context *ctx)
{
        static const struct inode_operations spufs_file_iops = {
                .setattr = spufs_setattr,
        };
        struct inode *inode;
        int ret;

        ret = -ENOSPC;
        inode = spufs_new_inode(sb, S_IFREG | mode);
        if (!inode)
                goto out;

        ret = 0;
        inode->i_op = &spufs_file_iops;
        inode->i_fop = fops;
        inode->i_size = size;
        inode->i_private = SPUFS_I(inode)->i_ctx = get_spu_context(ctx);
        d_make_persistent(dentry, inode);
out:
        return ret;
}

static void
spufs_evict_inode(struct inode *inode)
{
        struct spufs_inode_info *ei = SPUFS_I(inode);
        clear_inode(inode);
        if (ei->i_ctx)
                put_spu_context(ei->i_ctx);
        if (ei->i_gang)
                put_spu_gang(ei->i_gang);
}

/* Caller must hold parent->i_mutex */
static void spufs_rmdir(struct inode *parent, struct dentry *dir)
{
        struct spu_context *ctx = SPUFS_I(d_inode(dir))->i_ctx;

        locked_recursive_removal(dir, NULL);
        spu_forget(ctx);
}

static int spufs_fill_dir(struct dentry *dir,
                const struct spufs_tree_descr *files, umode_t mode,
                struct spu_context *ctx)
{
        while (files->name && files->name[0]) {
                int ret;
                struct dentry *dentry = d_alloc_name(dir, files->name);
                if (!dentry)
                        return -ENOMEM;
                ret = spufs_new_file(dir->d_sb, dentry, files->ops,
                                        files->mode & mode, files->size, ctx);
                dput(dentry);
                if (ret)
                        return ret;
                files++;
        }
        return 0;
}

static void unuse_gang(struct dentry *dir)
{
        struct inode *inode = dir->d_inode;
        struct spu_gang *gang = SPUFS_I(inode)->i_gang;

        if (gang) {
                bool dead;

                inode_lock(inode); // exclusion with spufs_create_context()
                dead = !--gang->alive;
                inode_unlock(inode);

                if (dead)
                        simple_recursive_removal(dir, NULL);
        }
}

static int spufs_dir_close(struct inode *inode, struct file *file)
{
        struct inode *parent;
        struct dentry *dir;

        dir = file->f_path.dentry;
        parent = d_inode(dir->d_parent);

        inode_lock_nested(parent, I_MUTEX_PARENT);
        spufs_rmdir(parent, dir);
        inode_unlock(parent);

        unuse_gang(dir->d_parent);
        return dcache_dir_close(inode, file);
}

const struct file_operations spufs_context_fops = {
        .open           = dcache_dir_open,
        .release        = spufs_dir_close,
        .llseek         = dcache_dir_lseek,
        .read           = generic_read_dir,
        .iterate_shared = dcache_readdir,
        .fsync          = noop_fsync,
};
EXPORT_SYMBOL_GPL(spufs_context_fops);

static int
spufs_mkdir(struct inode *dir, struct dentry *dentry, unsigned int flags,
                umode_t mode)
{
        int ret;
        struct inode *inode;
        struct spu_context *ctx;

        inode = spufs_new_inode(dir->i_sb, mode | S_IFDIR);
        if (!inode)
                return -ENOSPC;

        inode_init_owner(&nop_mnt_idmap, inode, dir, mode | S_IFDIR);
        ctx = alloc_spu_context(SPUFS_I(dir)->i_gang); /* XXX gang */
        SPUFS_I(inode)->i_ctx = ctx;
        if (!ctx) {
                iput(inode);
                return -ENOSPC;
        }

        ctx->flags = flags;
        inode->i_op = &simple_dir_inode_operations;
        inode->i_fop = &simple_dir_operations;

        inode_lock(inode);

        inc_nlink(dir);
        inc_nlink(inode);

        d_make_persistent(dentry, inode);

        if (flags & SPU_CREATE_NOSCHED)
                ret = spufs_fill_dir(dentry, spufs_dir_nosched_contents,
                                         mode, ctx);
        else
                ret = spufs_fill_dir(dentry, spufs_dir_contents, mode, ctx);

        if (!ret && spufs_get_sb_info(dir->i_sb)->debug)
                ret = spufs_fill_dir(dentry, spufs_dir_debug_contents,
                                mode, ctx);

        inode_unlock(inode);

        if (ret)
                spufs_rmdir(dir, dentry);

        return ret;
}

static int spufs_context_open(const struct path *path)
{
        FD_PREPARE(fdf, 0, dentry_open(path, O_RDONLY, current_cred()));
        if (fdf.err)
                return fdf.err;
        fd_prepare_file(fdf)->f_op = &spufs_context_fops;
        return fd_publish(fdf);
}

static struct spu_context *
spufs_assert_affinity(unsigned int flags, struct spu_gang *gang,
                                                struct file *filp)
{
        struct spu_context *tmp, *neighbor, *err;
        int count, node;
        int aff_supp;

        aff_supp = !list_empty(&(list_entry(cbe_spu_info[0].spus.next,
                                        struct spu, cbe_list))->aff_list);

        if (!aff_supp)
                return ERR_PTR(-EINVAL);

        if (flags & SPU_CREATE_GANG)
                return ERR_PTR(-EINVAL);

        if (flags & SPU_CREATE_AFFINITY_MEM &&
            gang->aff_ref_ctx &&
            gang->aff_ref_ctx->flags & SPU_CREATE_AFFINITY_MEM)
                return ERR_PTR(-EEXIST);

        if (gang->aff_flags & AFF_MERGED)
                return ERR_PTR(-EBUSY);

        neighbor = NULL;
        if (flags & SPU_CREATE_AFFINITY_SPU) {
                if (!filp || filp->f_op != &spufs_context_fops)
                        return ERR_PTR(-EINVAL);

                neighbor = get_spu_context(
                                SPUFS_I(file_inode(filp))->i_ctx);

                if (!list_empty(&neighbor->aff_list) && !(neighbor->aff_head) &&
                    !list_is_last(&neighbor->aff_list, &gang->aff_list_head) &&
                    !list_entry(neighbor->aff_list.next, struct spu_context,
                    aff_list)->aff_head) {
                        err = ERR_PTR(-EEXIST);
                        goto out_put_neighbor;
                }

                if (gang != neighbor->gang) {
                        err = ERR_PTR(-EINVAL);
                        goto out_put_neighbor;
                }

                count = 1;
                list_for_each_entry(tmp, &gang->aff_list_head, aff_list)
                        count++;
                if (list_empty(&neighbor->aff_list))
                        count++;

                for (node = 0; node < MAX_NUMNODES; node++) {
                        if ((cbe_spu_info[node].n_spus - atomic_read(
                                &cbe_spu_info[node].reserved_spus)) >= count)
                                break;
                }

                if (node == MAX_NUMNODES) {
                        err = ERR_PTR(-EEXIST);
                        goto out_put_neighbor;
                }
        }

        return neighbor;

out_put_neighbor:
        put_spu_context(neighbor);
        return err;
}

static void
spufs_set_affinity(unsigned int flags, struct spu_context *ctx,
                                        struct spu_context *neighbor)
{
        if (flags & SPU_CREATE_AFFINITY_MEM)
                ctx->gang->aff_ref_ctx = ctx;

        if (flags & SPU_CREATE_AFFINITY_SPU) {
                if (list_empty(&neighbor->aff_list)) {
                        list_add_tail(&neighbor->aff_list,
                                &ctx->gang->aff_list_head);
                        neighbor->aff_head = 1;
                }

                if (list_is_last(&neighbor->aff_list, &ctx->gang->aff_list_head)
                    || list_entry(neighbor->aff_list.next, struct spu_context,
                                                        aff_list)->aff_head) {
                        list_add(&ctx->aff_list, &neighbor->aff_list);
                } else  {
                        list_add_tail(&ctx->aff_list, &neighbor->aff_list);
                        if (neighbor->aff_head) {
                                neighbor->aff_head = 0;
                                ctx->aff_head = 1;
                        }
                }

                if (!ctx->gang->aff_ref_ctx)
                        ctx->gang->aff_ref_ctx = ctx;
        }
}

static int
spufs_create_context(struct inode *inode, struct dentry *dentry,
                        struct vfsmount *mnt, int flags, umode_t mode,
                        struct file *aff_filp)
{
        int ret;
        int affinity;
        struct spu_gang *gang = SPUFS_I(inode)->i_gang;
        struct spu_context *neighbor;
        struct path path = {.mnt = mnt, .dentry = dentry};

        if ((flags & SPU_CREATE_NOSCHED) &&
            !capable(CAP_SYS_NICE))
                return -EPERM;

        if ((flags & (SPU_CREATE_NOSCHED | SPU_CREATE_ISOLATE))
            == SPU_CREATE_ISOLATE)
                return -EINVAL;

        if ((flags & SPU_CREATE_ISOLATE) && !isolated_loader)
                return -ENODEV;

        if (gang) {
                if (!gang->alive)
                        return -ENOENT;
                gang->alive++;
        }

        neighbor = NULL;
        affinity = flags & (SPU_CREATE_AFFINITY_MEM | SPU_CREATE_AFFINITY_SPU);
        if (affinity) {
                if (!gang)
                        return -EINVAL;
                mutex_lock(&gang->aff_mutex);
                neighbor = spufs_assert_affinity(flags, gang, aff_filp);
                if (IS_ERR(neighbor)) {
                        ret = PTR_ERR(neighbor);
                        goto out_aff_unlock;
                }
        }

        ret = spufs_mkdir(inode, dentry, flags, mode & 0777);
        if (ret) {
                if (neighbor)
                        put_spu_context(neighbor);
                goto out_aff_unlock;
        }

        if (affinity) {
                spufs_set_affinity(flags, SPUFS_I(d_inode(dentry))->i_ctx,
                                                                neighbor);
                if (neighbor)
                        put_spu_context(neighbor);
        }

        ret = spufs_context_open(&path);
        if (ret < 0)
                spufs_rmdir(inode, dentry);

out_aff_unlock:
        if (affinity)
                mutex_unlock(&gang->aff_mutex);
        if (ret && gang)
                gang->alive--; // can't reach 0
        return ret;
}

static int
spufs_mkgang(struct inode *dir, struct dentry *dentry, umode_t mode)
{
        int ret;
        struct inode *inode;
        struct spu_gang *gang;

        ret = -ENOSPC;
        inode = spufs_new_inode(dir->i_sb, mode | S_IFDIR);
        if (!inode)
                goto out;

        ret = 0;
        inode_init_owner(&nop_mnt_idmap, inode, dir, mode | S_IFDIR);
        gang = alloc_spu_gang();
        SPUFS_I(inode)->i_ctx = NULL;
        SPUFS_I(inode)->i_gang = gang;
        if (!gang) {
                ret = -ENOMEM;
                goto out_iput;
        }

        inode->i_op = &simple_dir_inode_operations;
        inode->i_fop = &simple_dir_operations;

        inc_nlink(dir);
        inc_nlink(inode);
        d_make_persistent(dentry, inode);
        return ret;

out_iput:
        iput(inode);
out:
        return ret;
}

static int spufs_gang_close(struct inode *inode, struct file *file)
{
        unuse_gang(file->f_path.dentry);
        return dcache_dir_close(inode, file);
}

static const struct file_operations spufs_gang_fops = {
        .open           = dcache_dir_open,
        .release        = spufs_gang_close,
        .llseek         = dcache_dir_lseek,
        .read           = generic_read_dir,
        .iterate_shared = dcache_readdir,
        .fsync          = noop_fsync,
};

static int spufs_gang_open(const struct path *path)
{
        /*
         * get references for dget and mntget, will be released
         * in error path of *_open().
         */
        FD_PREPARE(fdf, 0, dentry_open(path, O_RDONLY, current_cred()));
        if (fdf.err)
                return fdf.err;
        fd_prepare_file(fdf)->f_op = &spufs_gang_fops;
        return fd_publish(fdf);
}

static int spufs_create_gang(struct inode *inode,
                        struct dentry *dentry,
                        struct vfsmount *mnt, umode_t mode)
{
        struct path path = {.mnt = mnt, .dentry = dentry};
        int ret;

        ret = spufs_mkgang(inode, dentry, mode & 0777);
        if (!ret) {
                ret = spufs_gang_open(&path);
                if (ret < 0)
                        unuse_gang(dentry);
        }
        return ret;
}


static struct file_system_type spufs_type;

long spufs_create(const struct path *path, struct dentry *dentry,
                unsigned int flags, umode_t mode, struct file *filp)
{
        struct inode *dir = d_inode(path->dentry);
        int ret;

        /* check if we are on spufs */
        if (path->dentry->d_sb->s_type != &spufs_type)
                return -EINVAL;

        /* don't accept undefined flags */
        if (flags & (~SPU_CREATE_FLAG_ALL))
                return -EINVAL;

        /* only threads can be underneath a gang */
        if (path->dentry != path->dentry->d_sb->s_root)
                if ((flags & SPU_CREATE_GANG) || !SPUFS_I(dir)->i_gang)
                        return -EINVAL;

        mode &= ~current_umask();

        if (flags & SPU_CREATE_GANG)
                ret = spufs_create_gang(dir, dentry, path->mnt, mode);
        else
                ret = spufs_create_context(dir, dentry, path->mnt, flags, mode,
                                            filp);
        if (ret >= 0)
                fsnotify_mkdir(dir, dentry);

        return ret;
}

/* File system initialization */
struct spufs_fs_context {
        kuid_t  uid;
        kgid_t  gid;
        umode_t mode;
};

enum {
        Opt_uid, Opt_gid, Opt_mode, Opt_debug,
};

static const struct fs_parameter_spec spufs_fs_parameters[] = {
        fsparam_u32     ("gid",                         Opt_gid),
        fsparam_u32oct  ("mode",                        Opt_mode),
        fsparam_u32     ("uid",                         Opt_uid),
        fsparam_flag    ("debug",                       Opt_debug),
        {}
};

static int spufs_show_options(struct seq_file *m, struct dentry *root)
{
        struct spufs_sb_info *sbi = spufs_get_sb_info(root->d_sb);
        struct inode *inode = root->d_inode;

        if (!uid_eq(inode->i_uid, GLOBAL_ROOT_UID))
                seq_printf(m, ",uid=%u",
                           from_kuid_munged(&init_user_ns, inode->i_uid));
        if (!gid_eq(inode->i_gid, GLOBAL_ROOT_GID))
                seq_printf(m, ",gid=%u",
                           from_kgid_munged(&init_user_ns, inode->i_gid));
        if ((inode->i_mode & S_IALLUGO) != 0775)
                seq_printf(m, ",mode=%o", inode->i_mode);
        if (sbi->debug)
                seq_puts(m, ",debug");
        return 0;
}

static int spufs_parse_param(struct fs_context *fc, struct fs_parameter *param)
{
        struct spufs_fs_context *ctx = fc->fs_private;
        struct spufs_sb_info *sbi = fc->s_fs_info;
        struct fs_parse_result result;
        kuid_t uid;
        kgid_t gid;
        int opt;

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

        switch (opt) {
        case Opt_uid:
                uid = make_kuid(current_user_ns(), result.uint_32);
                if (!uid_valid(uid))
                        return invalf(fc, "Unknown uid");
                ctx->uid = uid;
                break;
        case Opt_gid:
                gid = make_kgid(current_user_ns(), result.uint_32);
                if (!gid_valid(gid))
                        return invalf(fc, "Unknown gid");
                ctx->gid = gid;
                break;
        case Opt_mode:
                ctx->mode = result.uint_32 & S_IALLUGO;
                break;
        case Opt_debug:
                sbi->debug = true;
                break;
        }

        return 0;
}

static void spufs_exit_isolated_loader(void)
{
        free_pages((unsigned long) isolated_loader,
                        get_order(isolated_loader_size));
}

static void __init
spufs_init_isolated_loader(void)
{
        struct device_node *dn;
        const char *loader;
        int size;

        dn = of_find_node_by_path("/spu-isolation");
        if (!dn)
                return;

        loader = of_get_property(dn, "loader", &size);
        of_node_put(dn);
        if (!loader)
                return;

        /* the loader must be align on a 16 byte boundary */
        isolated_loader = (char *)__get_free_pages(GFP_KERNEL, get_order(size));
        if (!isolated_loader)
                return;

        isolated_loader_size = size;
        memcpy(isolated_loader, loader, size);
        printk(KERN_INFO "spufs: SPU isolation mode enabled\n");
}

static int spufs_create_root(struct super_block *sb, struct fs_context *fc)
{
        struct spufs_fs_context *ctx = fc->fs_private;
        struct inode *inode;

        if (!spu_management_ops)
                return -ENODEV;

        inode = spufs_new_inode(sb, S_IFDIR | ctx->mode);
        if (!inode)
                return -ENOMEM;

        inode->i_uid = ctx->uid;
        inode->i_gid = ctx->gid;
        inode->i_op = &simple_dir_inode_operations;
        inode->i_fop = &simple_dir_operations;
        SPUFS_I(inode)->i_ctx = NULL;
        inc_nlink(inode);

        sb->s_root = d_make_root(inode);
        if (!sb->s_root)
                return -ENOMEM;
        return 0;
}

static const struct super_operations spufs_ops = {
        .alloc_inode    = spufs_alloc_inode,
        .free_inode     = spufs_free_inode,
        .statfs         = simple_statfs,
        .evict_inode    = spufs_evict_inode,
        .show_options   = spufs_show_options,
};

static int spufs_fill_super(struct super_block *sb, struct fs_context *fc)
{
        sb->s_maxbytes = MAX_LFS_FILESIZE;
        sb->s_blocksize = PAGE_SIZE;
        sb->s_blocksize_bits = PAGE_SHIFT;
        sb->s_magic = SPUFS_MAGIC;
        sb->s_op = &spufs_ops;

        return spufs_create_root(sb, fc);
}

static int spufs_get_tree(struct fs_context *fc)
{
        return get_tree_single(fc, spufs_fill_super);
}

static void spufs_free_fc(struct fs_context *fc)
{
        kfree(fc->s_fs_info);
}

static const struct fs_context_operations spufs_context_ops = {
        .free           = spufs_free_fc,
        .parse_param    = spufs_parse_param,
        .get_tree       = spufs_get_tree,
};

static int spufs_init_fs_context(struct fs_context *fc)
{
        struct spufs_fs_context *ctx;
        struct spufs_sb_info *sbi;

        ctx = kzalloc_obj(struct spufs_fs_context);
        if (!ctx)
                goto nomem;

        sbi = kzalloc_obj(struct spufs_sb_info);
        if (!sbi)
                goto nomem_ctx;

        ctx->uid = current_uid();
        ctx->gid = current_gid();
        ctx->mode = 0755;

        fc->fs_private = ctx;
        fc->s_fs_info = sbi;
        fc->ops = &spufs_context_ops;
        return 0;

nomem_ctx:
        kfree(ctx);
nomem:
        return -ENOMEM;
}

static struct file_system_type spufs_type = {
        .owner = THIS_MODULE,
        .name = "spufs",
        .init_fs_context = spufs_init_fs_context,
        .parameters     = spufs_fs_parameters,
        .kill_sb = kill_anon_super,
};
MODULE_ALIAS_FS("spufs");

static int __init spufs_init(void)
{
        int ret;

        ret = -ENODEV;
        if (!spu_management_ops)
                goto out;

        ret = -ENOMEM;
        spufs_inode_cache = kmem_cache_create("spufs_inode_cache",
                        sizeof(struct spufs_inode_info), 0,
                        SLAB_HWCACHE_ALIGN|SLAB_ACCOUNT, spufs_init_once);

        if (!spufs_inode_cache)
                goto out;
        ret = spu_sched_init();
        if (ret)
                goto out_cache;
        ret = register_spu_syscalls(&spufs_calls);
        if (ret)
                goto out_sched;
        ret = register_filesystem(&spufs_type);
        if (ret)
                goto out_syscalls;

        spufs_init_isolated_loader();

        return 0;

out_syscalls:
        unregister_spu_syscalls(&spufs_calls);
out_sched:
        spu_sched_exit();
out_cache:
        kmem_cache_destroy(spufs_inode_cache);
out:
        return ret;
}
module_init(spufs_init);

static void __exit spufs_exit(void)
{
        spu_sched_exit();
        spufs_exit_isolated_loader();
        unregister_spu_syscalls(&spufs_calls);
        unregister_filesystem(&spufs_type);
        kmem_cache_destroy(spufs_inode_cache);
}
module_exit(spufs_exit);

MODULE_DESCRIPTION("SPU file system");
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Arnd Bergmann <arndb@de.ibm.com>");