new helper: file_inode(file)

[mirror_ubuntu-jammy-kernel.git] / fs / hppfs / hppfs.c

/*
 * Copyright (C) 2002 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
 * Licensed under the GPL
 */

#include <linux/ctype.h>
#include <linux/dcache.h>
#include <linux/file.h>
#include <linux/fs.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/list.h>
#include <linux/module.h>
#include <linux/mount.h>
#include <linux/slab.h>
#include <linux/statfs.h>
#include <linux/types.h>
#include <linux/pid_namespace.h>
#include <linux/namei.h>
#include <asm/uaccess.h>
#include <os.h>

static struct inode *get_inode(struct super_block *, struct dentry *);

struct hppfs_data {
        struct list_head list;
        char contents[PAGE_SIZE - sizeof(struct list_head)];
};

struct hppfs_private {
        struct file *proc_file;
        int host_fd;
        loff_t len;
        struct hppfs_data *contents;
};

struct hppfs_inode_info {
        struct dentry *proc_dentry;
        struct inode vfs_inode;
};

static inline struct hppfs_inode_info *HPPFS_I(struct inode *inode)
{
        return container_of(inode, struct hppfs_inode_info, vfs_inode);
}

#define HPPFS_SUPER_MAGIC 0xb00000ee

static const struct super_operations hppfs_sbops;

static int is_pid(struct dentry *dentry)
{
        struct super_block *sb;
        int i;

        sb = dentry->d_sb;
        if (dentry->d_parent != sb->s_root)
                return 0;

        for (i = 0; i < dentry->d_name.len; i++) {
                if (!isdigit(dentry->d_name.name[i]))
                        return 0;
        }
        return 1;
}

static char *dentry_name(struct dentry *dentry, int extra)
{
        struct dentry *parent;
        char *root, *name;
        const char *seg_name;
        int len, seg_len;

        len = 0;
        parent = dentry;
        while (parent->d_parent != parent) {
                if (is_pid(parent))
                        len += strlen("pid") + 1;
                else len += parent->d_name.len + 1;
                parent = parent->d_parent;
        }

        root = "proc";
        len += strlen(root);
        name = kmalloc(len + extra + 1, GFP_KERNEL);
        if (name == NULL)
                return NULL;

        name[len] = '\0';
        parent = dentry;
        while (parent->d_parent != parent) {
                if (is_pid(parent)) {
                        seg_name = "pid";
                        seg_len = strlen("pid");
                }
                else {
                        seg_name = parent->d_name.name;
                        seg_len = parent->d_name.len;
                }

                len -= seg_len + 1;
                name[len] = '/';
                strncpy(&name[len + 1], seg_name, seg_len);
                parent = parent->d_parent;
        }
        strncpy(name, root, strlen(root));
        return name;
}

static int file_removed(struct dentry *dentry, const char *file)
{
        char *host_file;
        int extra, fd;

        extra = 0;
        if (file != NULL)
                extra += strlen(file) + 1;

        host_file = dentry_name(dentry, extra + strlen("/remove"));
        if (host_file == NULL) {
                printk(KERN_ERR "file_removed : allocation failed\n");
                return -ENOMEM;
        }

        if (file != NULL) {
                strcat(host_file, "/");
                strcat(host_file, file);
        }
        strcat(host_file, "/remove");

        fd = os_open_file(host_file, of_read(OPENFLAGS()), 0);
        kfree(host_file);
        if (fd > 0) {
                os_close_file(fd);
                return 1;
        }
        return 0;
}

static struct dentry *hppfs_lookup(struct inode *ino, struct dentry *dentry,
                                   unsigned int flags)
{
        struct dentry *proc_dentry, *parent;
        struct qstr *name = &dentry->d_name;
        struct inode *inode;
        int err, deleted;

        deleted = file_removed(dentry, NULL);
        if (deleted < 0)
                return ERR_PTR(deleted);
        else if (deleted)
                return ERR_PTR(-ENOENT);

        parent = HPPFS_I(ino)->proc_dentry;
        mutex_lock(&parent->d_inode->i_mutex);
        proc_dentry = lookup_one_len(name->name, parent, name->len);
        mutex_unlock(&parent->d_inode->i_mutex);

        if (IS_ERR(proc_dentry))
                return proc_dentry;

        err = -ENOMEM;
        inode = get_inode(ino->i_sb, proc_dentry);
        if (!inode)
                goto out;

        d_add(dentry, inode);
        return NULL;

 out:
        return ERR_PTR(err);
}

static const struct inode_operations hppfs_file_iops = {
};

static ssize_t read_proc(struct file *file, char __user *buf, ssize_t count,
                         loff_t *ppos, int is_user)
{
        ssize_t (*read)(struct file *, char __user *, size_t, loff_t *);
        ssize_t n;

        read = file_inode(file)->i_fop->read;

        if (!is_user)
                set_fs(KERNEL_DS);

        n = (*read)(file, buf, count, &file->f_pos);

        if (!is_user)
                set_fs(USER_DS);

        if (ppos)
                *ppos = file->f_pos;
        return n;
}

static ssize_t hppfs_read_file(int fd, char __user *buf, ssize_t count)
{
        ssize_t n;
        int cur, err;
        char *new_buf;

        n = -ENOMEM;
        new_buf = kmalloc(PAGE_SIZE, GFP_KERNEL);
        if (new_buf == NULL) {
                printk(KERN_ERR "hppfs_read_file : kmalloc failed\n");
                goto out;
        }
        n = 0;
        while (count > 0) {
                cur = min_t(ssize_t, count, PAGE_SIZE);
                err = os_read_file(fd, new_buf, cur);
                if (err < 0) {
                        printk(KERN_ERR "hppfs_read : read failed, "
                               "errno = %d\n", err);
                        n = err;
                        goto out_free;
                } else if (err == 0)
                        break;

                if (copy_to_user(buf, new_buf, err)) {
                        n = -EFAULT;
                        goto out_free;
                }
                n += err;
                count -= err;
        }
 out_free:
        kfree(new_buf);
 out:
        return n;
}

static ssize_t hppfs_read(struct file *file, char __user *buf, size_t count,
                          loff_t *ppos)
{
        struct hppfs_private *hppfs = file->private_data;
        struct hppfs_data *data;
        loff_t off;
        int err;

        if (hppfs->contents != NULL) {
                int rem;

                if (*ppos >= hppfs->len)
                        return 0;

                data = hppfs->contents;
                off = *ppos;
                while (off >= sizeof(data->contents)) {
                        data = list_entry(data->list.next, struct hppfs_data,
                                          list);
                        off -= sizeof(data->contents);
                }

                if (off + count > hppfs->len)
                        count = hppfs->len - off;
                rem = copy_to_user(buf, &data->contents[off], count);
                *ppos += count - rem;
                if (rem > 0)
                        return -EFAULT;
        } else if (hppfs->host_fd != -1) {
                err = os_seek_file(hppfs->host_fd, *ppos);
                if (err) {
                        printk(KERN_ERR "hppfs_read : seek failed, "
                               "errno = %d\n", err);
                        return err;
                }
                err = hppfs_read_file(hppfs->host_fd, buf, count);
                if (err < 0) {
                        printk(KERN_ERR "hppfs_read: read failed: %d\n", err);
                        return err;
                }
                count = err;
                if (count > 0)
                        *ppos += count;
        }
        else count = read_proc(hppfs->proc_file, buf, count, ppos, 1);

        return count;
}

static ssize_t hppfs_write(struct file *file, const char __user *buf,
                           size_t len, loff_t *ppos)
{
        struct hppfs_private *data = file->private_data;
        struct file *proc_file = data->proc_file;
        ssize_t (*write)(struct file *, const char __user *, size_t, loff_t *);

        write = file_inode(proc_file)->i_fop->write;
        return (*write)(proc_file, buf, len, ppos);
}

static int open_host_sock(char *host_file, int *filter_out)
{
        char *end;
        int fd;

        end = &host_file[strlen(host_file)];
        strcpy(end, "/rw");
        *filter_out = 1;
        fd = os_connect_socket(host_file);
        if (fd > 0)
                return fd;

        strcpy(end, "/r");
        *filter_out = 0;
        fd = os_connect_socket(host_file);
        return fd;
}

static void free_contents(struct hppfs_data *head)
{
        struct hppfs_data *data;
        struct list_head *ele, *next;

        if (head == NULL)
                return;

        list_for_each_safe(ele, next, &head->list) {
                data = list_entry(ele, struct hppfs_data, list);
                kfree(data);
        }
        kfree(head);
}

static struct hppfs_data *hppfs_get_data(int fd, int filter,
                                         struct file *proc_file,
                                         struct file *hppfs_file,
                                         loff_t *size_out)
{
        struct hppfs_data *data, *new, *head;
        int n, err;

        err = -ENOMEM;
        data = kmalloc(sizeof(*data), GFP_KERNEL);
        if (data == NULL) {
                printk(KERN_ERR "hppfs_get_data : head allocation failed\n");
                goto failed;
        }

        INIT_LIST_HEAD(&data->list);

        head = data;
        *size_out = 0;

        if (filter) {
                while ((n = read_proc(proc_file, data->contents,
                                      sizeof(data->contents), NULL, 0)) > 0)
                        os_write_file(fd, data->contents, n);
                err = os_shutdown_socket(fd, 0, 1);
                if (err) {
                        printk(KERN_ERR "hppfs_get_data : failed to shut down "
                               "socket\n");
                        goto failed_free;
                }
        }
        while (1) {
                n = os_read_file(fd, data->contents, sizeof(data->contents));
                if (n < 0) {
                        err = n;
                        printk(KERN_ERR "hppfs_get_data : read failed, "
                               "errno = %d\n", err);
                        goto failed_free;
                } else if (n == 0)
                        break;

                *size_out += n;

                if (n < sizeof(data->contents))
                        break;

                new = kmalloc(sizeof(*data), GFP_KERNEL);
                if (new == 0) {
                        printk(KERN_ERR "hppfs_get_data : data allocation "
                               "failed\n");
                        err = -ENOMEM;
                        goto failed_free;
                }

                INIT_LIST_HEAD(&new->list);
                list_add(&new->list, &data->list);
                data = new;
        }
        return head;

 failed_free:
        free_contents(head);
 failed:
        return ERR_PTR(err);
}

static struct hppfs_private *hppfs_data(void)
{
        struct hppfs_private *data;

        data = kmalloc(sizeof(*data), GFP_KERNEL);
        if (data == NULL)
                return data;

        *data = ((struct hppfs_private ) { .host_fd             = -1,
                                           .len                 = -1,
                                           .contents            = NULL } );
        return data;
}

static int file_mode(int fmode)
{
        if (fmode == (FMODE_READ | FMODE_WRITE))
                return O_RDWR;
        if (fmode == FMODE_READ)
                return O_RDONLY;
        if (fmode == FMODE_WRITE)
                return O_WRONLY;
        return 0;
}

static int hppfs_open(struct inode *inode, struct file *file)
{
        const struct cred *cred = file->f_cred;
        struct hppfs_private *data;
        struct path path;
        char *host_file;
        int err, fd, type, filter;

        err = -ENOMEM;
        data = hppfs_data();
        if (data == NULL)
                goto out;

        host_file = dentry_name(file->f_path.dentry, strlen("/rw"));
        if (host_file == NULL)
                goto out_free2;

        path.mnt = inode->i_sb->s_fs_info;
        path.dentry = HPPFS_I(inode)->proc_dentry;

        /* XXX This isn't closed anywhere */
        data->proc_file = dentry_open(&path, file_mode(file->f_mode), cred);
        err = PTR_ERR(data->proc_file);
        if (IS_ERR(data->proc_file))
                goto out_free1;

        type = os_file_type(host_file);
        if (type == OS_TYPE_FILE) {
                fd = os_open_file(host_file, of_read(OPENFLAGS()), 0);
                if (fd >= 0)
                        data->host_fd = fd;
                else
                        printk(KERN_ERR "hppfs_open : failed to open '%s', "
                               "errno = %d\n", host_file, -fd);

                data->contents = NULL;
        } else if (type == OS_TYPE_DIR) {
                fd = open_host_sock(host_file, &filter);
                if (fd > 0) {
                        data->contents = hppfs_get_data(fd, filter,
                                                        data->proc_file,
                                                        file, &data->len);
                        if (!IS_ERR(data->contents))
                                data->host_fd = fd;
                } else
                        printk(KERN_ERR "hppfs_open : failed to open a socket "
                               "in '%s', errno = %d\n", host_file, -fd);
        }
        kfree(host_file);

        file->private_data = data;
        return 0;

 out_free1:
        kfree(host_file);
 out_free2:
        free_contents(data->contents);
        kfree(data);
 out:
        return err;
}

static int hppfs_dir_open(struct inode *inode, struct file *file)
{
        const struct cred *cred = file->f_cred;
        struct hppfs_private *data;
        struct path path;
        int err;

        err = -ENOMEM;
        data = hppfs_data();
        if (data == NULL)
                goto out;

        path.mnt = inode->i_sb->s_fs_info;
        path.dentry = HPPFS_I(inode)->proc_dentry;
        data->proc_file = dentry_open(&path, file_mode(file->f_mode), cred);
        err = PTR_ERR(data->proc_file);
        if (IS_ERR(data->proc_file))
                goto out_free;

        file->private_data = data;
        return 0;

 out_free:
        kfree(data);
 out:
        return err;
}

static loff_t hppfs_llseek(struct file *file, loff_t off, int where)
{
        struct hppfs_private *data = file->private_data;
        struct file *proc_file = data->proc_file;
        loff_t (*llseek)(struct file *, loff_t, int);
        loff_t ret;

        llseek = file_inode(proc_file)->i_fop->llseek;
        if (llseek != NULL) {
                ret = (*llseek)(proc_file, off, where);
                if (ret < 0)
                        return ret;
        }

        return default_llseek(file, off, where);
}

static const struct file_operations hppfs_file_fops = {
        .owner          = NULL,
        .llseek         = hppfs_llseek,
        .read           = hppfs_read,
        .write          = hppfs_write,
        .open           = hppfs_open,
};

struct hppfs_dirent {
        void *vfs_dirent;
        filldir_t filldir;
        struct dentry *dentry;
};

static int hppfs_filldir(void *d, const char *name, int size,
                         loff_t offset, u64 inode, unsigned int type)
{
        struct hppfs_dirent *dirent = d;

        if (file_removed(dirent->dentry, name))
                return 0;

        return (*dirent->filldir)(dirent->vfs_dirent, name, size, offset,
                                  inode, type);
}

static int hppfs_readdir(struct file *file, void *ent, filldir_t filldir)
{
        struct hppfs_private *data = file->private_data;
        struct file *proc_file = data->proc_file;
        int (*readdir)(struct file *, void *, filldir_t);
        struct hppfs_dirent dirent = ((struct hppfs_dirent)
                                      { .vfs_dirent     = ent,
                                        .filldir        = filldir,
                                        .dentry         = file->f_path.dentry
                                      });
        int err;

        readdir = file_inode(proc_file)->i_fop->readdir;

        proc_file->f_pos = file->f_pos;
        err = (*readdir)(proc_file, &dirent, hppfs_filldir);
        file->f_pos = proc_file->f_pos;

        return err;
}

static int hppfs_fsync(struct file *file, loff_t start, loff_t end,
                       int datasync)
{
        return filemap_write_and_wait_range(file->f_mapping, start, end);
}

static const struct file_operations hppfs_dir_fops = {
        .owner          = NULL,
        .readdir        = hppfs_readdir,
        .open           = hppfs_dir_open,
        .fsync          = hppfs_fsync,
        .llseek         = default_llseek,
};

static int hppfs_statfs(struct dentry *dentry, struct kstatfs *sf)
{
        sf->f_blocks = 0;
        sf->f_bfree = 0;
        sf->f_bavail = 0;
        sf->f_files = 0;
        sf->f_ffree = 0;
        sf->f_type = HPPFS_SUPER_MAGIC;
        return 0;
}

static struct inode *hppfs_alloc_inode(struct super_block *sb)
{
        struct hppfs_inode_info *hi;

        hi = kmalloc(sizeof(*hi), GFP_KERNEL);
        if (!hi)
                return NULL;

        hi->proc_dentry = NULL;
        inode_init_once(&hi->vfs_inode);
        return &hi->vfs_inode;
}

void hppfs_evict_inode(struct inode *ino)
{
        clear_inode(ino);
        dput(HPPFS_I(ino)->proc_dentry);
        mntput(ino->i_sb->s_fs_info);
}

static void hppfs_i_callback(struct rcu_head *head)
{
        struct inode *inode = container_of(head, struct inode, i_rcu);
        kfree(HPPFS_I(inode));
}

static void hppfs_destroy_inode(struct inode *inode)
{
        call_rcu(&inode->i_rcu, hppfs_i_callback);
}

static const struct super_operations hppfs_sbops = {
        .alloc_inode    = hppfs_alloc_inode,
        .destroy_inode  = hppfs_destroy_inode,
        .evict_inode    = hppfs_evict_inode,
        .statfs         = hppfs_statfs,
};

static int hppfs_readlink(struct dentry *dentry, char __user *buffer,
                          int buflen)
{
        struct dentry *proc_dentry = HPPFS_I(dentry->d_inode)->proc_dentry;
        return proc_dentry->d_inode->i_op->readlink(proc_dentry, buffer,
                                                    buflen);
}

static void *hppfs_follow_link(struct dentry *dentry, struct nameidata *nd)
{
        struct dentry *proc_dentry = HPPFS_I(dentry->d_inode)->proc_dentry;

        return proc_dentry->d_inode->i_op->follow_link(proc_dentry, nd);
}

static void hppfs_put_link(struct dentry *dentry, struct nameidata *nd,
                           void *cookie)
{
        struct dentry *proc_dentry = HPPFS_I(dentry->d_inode)->proc_dentry;

        if (proc_dentry->d_inode->i_op->put_link)
                proc_dentry->d_inode->i_op->put_link(proc_dentry, nd, cookie);
}

static const struct inode_operations hppfs_dir_iops = {
        .lookup         = hppfs_lookup,
};

static const struct inode_operations hppfs_link_iops = {
        .readlink       = hppfs_readlink,
        .follow_link    = hppfs_follow_link,
        .put_link       = hppfs_put_link,
};

static struct inode *get_inode(struct super_block *sb, struct dentry *dentry)
{
        struct inode *proc_ino = dentry->d_inode;
        struct inode *inode = new_inode(sb);

        if (!inode) {
                dput(dentry);
                return NULL;
        }

        if (S_ISDIR(dentry->d_inode->i_mode)) {
                inode->i_op = &hppfs_dir_iops;
                inode->i_fop = &hppfs_dir_fops;
        } else if (S_ISLNK(dentry->d_inode->i_mode)) {
                inode->i_op = &hppfs_link_iops;
                inode->i_fop = &hppfs_file_fops;
        } else {
                inode->i_op = &hppfs_file_iops;
                inode->i_fop = &hppfs_file_fops;
        }

        HPPFS_I(inode)->proc_dentry = dentry;

        inode->i_uid = proc_ino->i_uid;
        inode->i_gid = proc_ino->i_gid;
        inode->i_atime = proc_ino->i_atime;
        inode->i_mtime = proc_ino->i_mtime;
        inode->i_ctime = proc_ino->i_ctime;
        inode->i_ino = proc_ino->i_ino;
        inode->i_mode = proc_ino->i_mode;
        set_nlink(inode, proc_ino->i_nlink);
        inode->i_size = proc_ino->i_size;
        inode->i_blocks = proc_ino->i_blocks;

        return inode;
}

static int hppfs_fill_super(struct super_block *sb, void *d, int silent)
{
        struct inode *root_inode;
        struct vfsmount *proc_mnt;
        int err = -ENOENT;

        proc_mnt = mntget(task_active_pid_ns(current)->proc_mnt);
        if (IS_ERR(proc_mnt))
                goto out;

        sb->s_blocksize = 1024;
        sb->s_blocksize_bits = 10;
        sb->s_magic = HPPFS_SUPER_MAGIC;
        sb->s_op = &hppfs_sbops;
        sb->s_fs_info = proc_mnt;

        err = -ENOMEM;
        root_inode = get_inode(sb, dget(proc_mnt->mnt_root));
        sb->s_root = d_make_root(root_inode);
        if (!sb->s_root)
                goto out_mntput;

        return 0;

 out_mntput:
        mntput(proc_mnt);
 out:
        return(err);
}

static struct dentry *hppfs_read_super(struct file_system_type *type,
                            int flags, const char *dev_name,
                            void *data)
{
        return mount_nodev(type, flags, data, hppfs_fill_super);
}

static struct file_system_type hppfs_type = {
        .owner          = THIS_MODULE,
        .name           = "hppfs",
        .mount          = hppfs_read_super,
        .kill_sb        = kill_anon_super,
        .fs_flags       = 0,
};

static int __init init_hppfs(void)
{
        return register_filesystem(&hppfs_type);
}

static void __exit exit_hppfs(void)
{
        unregister_filesystem(&hppfs_type);
}

module_init(init_hppfs)
module_exit(exit_hppfs)
MODULE_LICENSE("GPL");