inode.c

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/*
 *    Hypervisor filesystem for Linux on s390.
 *
 *    Copyright IBM Corp. 2006, 2008
 *    Author(s): Michael Holzheu <[email protected]>
 */

#define KMSG_COMPONENT "hypfs"
#define pr_fmt(fmt) KMSG_COMPONENT ": " fmt

#include <linux/types.h>
#include <linux/errno.h>
#include <linux/fs.h>
#include <linux/namei.h>
#include <linux/vfs.h>
#include <linux/slab.h>
#include <linux/pagemap.h>
#include <linux/time.h>
#include <linux/parser.h>
#include <linux/sysfs.h>
#include <linux/module.h>
#include <linux/seq_file.h>
#include <linux/mount.h>
#include <asm/ebcdic.h>
#include "hypfs.h"

#define HYPFS_MAGIC 0x687970    /* ASCII 'hyp' */
#define TMP_SIZE 64     /* size of temporary buffers */

static struct dentry *hypfs_create_update_file(struct super_block *sb,
                           struct dentry *dir);

struct hypfs_sb_info {
    kuid_t uid;         /* uid used for files and dirs */
    kgid_t gid;         /* gid used for files and dirs */
    struct dentry *update_file; /* file to trigger update */
    time_t last_update;     /* last update time in secs since 1970 */
    struct mutex lock;      /* lock to protect update process */
};

static const struct file_operations hypfs_file_ops;
static struct file_system_type hypfs_type;
static const struct super_operations hypfs_s_ops;

/* start of list of all dentries, which have to be deleted on update */
static struct dentry *hypfs_last_dentry;

static void hypfs_update_update(struct super_block *sb)
{
    struct hypfs_sb_info *sb_info = sb->s_fs_info;
    struct inode *inode = sb_info->update_file->d_inode;

    sb_info->last_update = get_seconds();
    inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
}

/* directory tree removal functions */

static void hypfs_add_dentry(struct dentry *dentry)
{
    dentry->d_fsdata = hypfs_last_dentry;
    hypfs_last_dentry = dentry;
}

static inline int hypfs_positive(struct dentry *dentry)
{
    return dentry->d_inode && !d_unhashed(dentry);
}

static void hypfs_remove(struct dentry *dentry)
{
    struct dentry *parent;

    parent = dentry->d_parent;
    mutex_lock(&parent->d_inode->i_mutex);
    if (hypfs_positive(dentry)) {
        if (S_ISDIR(dentry->d_inode->i_mode))
            simple_rmdir(parent->d_inode, dentry);
        else
            simple_unlink(parent->d_inode, dentry);
    }
    d_delete(dentry);
    dput(dentry);
    mutex_unlock(&parent->d_inode->i_mutex);
}

static void hypfs_delete_tree(struct dentry *root)
{
    while (hypfs_last_dentry) {
        struct dentry *next_dentry;
        next_dentry = hypfs_last_dentry->d_fsdata;
        hypfs_remove(hypfs_last_dentry);
        hypfs_last_dentry = next_dentry;
    }
}

static struct inode *hypfs_make_inode(struct super_block *sb, umode_t mode)
{
    struct inode *ret = new_inode(sb);

    if (ret) {
        struct hypfs_sb_info *hypfs_info = sb->s_fs_info;
        ret->i_ino = get_next_ino();
        ret->i_mode = mode;
        ret->i_uid = hypfs_info->uid;
        ret->i_gid = hypfs_info->gid;
        ret->i_atime = ret->i_mtime = ret->i_ctime = CURRENT_TIME;
        if (S_ISDIR(mode))
            set_nlink(ret, 2);
    }
    return ret;
}

static void hypfs_evict_inode(struct inode *inode)
{
    clear_inode(inode);
    kfree(inode->i_private);
}

static int hypfs_open(struct inode *inode, struct file *filp)
{
    char *data = filp->f_path.dentry->d_inode->i_private;
    struct hypfs_sb_info *fs_info;

    if (filp->f_mode & FMODE_WRITE) {
        if (!(inode->i_mode & S_IWUGO))
            return -EACCES;
    }
    if (filp->f_mode & FMODE_READ) {
        if (!(inode->i_mode & S_IRUGO))
            return -EACCES;
    }

    fs_info = inode->i_sb->s_fs_info;
    if(data) {
        mutex_lock(&fs_info->lock);
        filp->private_data = kstrdup(data, GFP_KERNEL);
        if (!filp->private_data) {
            mutex_unlock(&fs_info->lock);
            return -ENOMEM;
        }
        mutex_unlock(&fs_info->lock);
    }
    return nonseekable_open(inode, filp);
}

static ssize_t hypfs_aio_read(struct kiocb *iocb, const struct iovec *iov,
                  unsigned long nr_segs, loff_t offset)
{
    char *data;
    ssize_t ret;
    struct file *filp = iocb->ki_filp;
    /* XXX: temporary */
    char __user *buf = iov[0].iov_base;
    size_t count = iov[0].iov_len;

    if (nr_segs != 1)
        return -EINVAL;

    data = filp->private_data;
    ret = simple_read_from_buffer(buf, count, &offset, data, strlen(data));
    if (ret <= 0)
        return ret;

    iocb->ki_pos += ret;
    file_accessed(filp);

    return ret;
}
static ssize_t hypfs_aio_write(struct kiocb *iocb, const struct iovec *iov,
                  unsigned long nr_segs, loff_t offset)
{
    int rc;
    struct super_block *sb;
    struct hypfs_sb_info *fs_info;
    size_t count = iov_length(iov, nr_segs);

    sb = iocb->ki_filp->f_path.dentry->d_inode->i_sb;
    fs_info = sb->s_fs_info;
    /*
     * Currently we only allow one update per second for two reasons:
     * 1. diag 204 is VERY expensive
     * 2. If several processes do updates in parallel and then read the
     *    hypfs data, the likelihood of collisions is reduced, if we restrict
     *    the minimum update interval. A collision occurs, if during the
     *    data gathering of one process another process triggers an update
     *    If the first process wants to ensure consistent data, it has
     *    to restart data collection in this case.
     */
    mutex_lock(&fs_info->lock);
    if (fs_info->last_update == get_seconds()) {
        rc = -EBUSY;
        goto out;
    }
    hypfs_delete_tree(sb->s_root);
    if (MACHINE_IS_VM)
        rc = hypfs_vm_create_files(sb, sb->s_root);
    else
        rc = hypfs_diag_create_files(sb, sb->s_root);
    if (rc) {
        pr_err("Updating the hypfs tree failed\n");
        hypfs_delete_tree(sb->s_root);
        goto out;
    }
    hypfs_update_update(sb);
    rc = count;
out:
    mutex_unlock(&fs_info->lock);
    return rc;
}

static int hypfs_release(struct inode *inode, struct file *filp)
{
    kfree(filp->private_data);
    return 0;
}

enum { opt_uid, opt_gid, opt_err };

static const match_table_t hypfs_tokens = {
    {opt_uid, "uid=%u"},
    {opt_gid, "gid=%u"},
    {opt_err, NULL}
};

static int hypfs_parse_options(char *options, struct super_block *sb)
{
    char *str;
    substring_t args[MAX_OPT_ARGS];
    kuid_t uid;
    kgid_t gid;

    if (!options)
        return 0;
    while ((str = strsep(&options, ",")) != NULL) {
        int token, option;
        struct hypfs_sb_info *hypfs_info = sb->s_fs_info;

        if (!*str)
            continue;
        token = match_token(str, hypfs_tokens, args);
        switch (token) {
        case opt_uid:
            if (match_int(&args[0], &option))
                return -EINVAL;
            uid = make_kuid(current_user_ns(), option);
            if (!uid_valid(uid))
                return -EINVAL;
            hypfs_info->uid = uid;
            break;
        case opt_gid:
            if (match_int(&args[0], &option))
                return -EINVAL;
            gid = make_kgid(current_user_ns(), option);
            if (!gid_valid(gid))
                return -EINVAL;
            hypfs_info->gid = gid;
            break;
        case opt_err:
        default:
            pr_err("%s is not a valid mount option\n", str);
            return -EINVAL;
        }
    }
    return 0;
}

static int hypfs_show_options(struct seq_file *s, struct dentry *root)
{
    struct hypfs_sb_info *hypfs_info = root->d_sb->s_fs_info;

    seq_printf(s, ",uid=%u", from_kuid_munged(&init_user_ns, hypfs_info->uid));
    seq_printf(s, ",gid=%u", from_kgid_munged(&init_user_ns, hypfs_info->gid));
    return 0;
}

static int hypfs_fill_super(struct super_block *sb, void *data, int silent)
{
    struct inode *root_inode;
    struct dentry *root_dentry;
    int rc = 0;
    struct hypfs_sb_info *sbi;

    sbi = kzalloc(sizeof(struct hypfs_sb_info), GFP_KERNEL);
    if (!sbi)
        return -ENOMEM;
    mutex_init(&sbi->lock);
    sbi->uid = current_uid();
    sbi->gid = current_gid();
    sb->s_fs_info = sbi;
    sb->s_blocksize = PAGE_CACHE_SIZE;
    sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
    sb->s_magic = HYPFS_MAGIC;
    sb->s_op = &hypfs_s_ops;
    if (hypfs_parse_options(data, sb))
        return -EINVAL;
    root_inode = hypfs_make_inode(sb, S_IFDIR | 0755);
    if (!root_inode)
        return -ENOMEM;
    root_inode->i_op = &simple_dir_inode_operations;
    root_inode->i_fop = &simple_dir_operations;
    sb->s_root = root_dentry = d_make_root(root_inode);
    if (!root_dentry)
        return -ENOMEM;
    if (MACHINE_IS_VM)
        rc = hypfs_vm_create_files(sb, root_dentry);
    else
        rc = hypfs_diag_create_files(sb, root_dentry);
    if (rc)
        return rc;
    sbi->update_file = hypfs_create_update_file(sb, root_dentry);
    if (IS_ERR(sbi->update_file))
        return PTR_ERR(sbi->update_file);
    hypfs_update_update(sb);
    pr_info("Hypervisor filesystem mounted\n");
    return 0;
}

static struct dentry *hypfs_mount(struct file_system_type *fst, int flags,
            const char *devname, void *data)
{
    return mount_single(fst, flags, data, hypfs_fill_super);
}

static void hypfs_kill_super(struct super_block *sb)
{
    struct hypfs_sb_info *sb_info = sb->s_fs_info;

    if (sb->s_root)
        hypfs_delete_tree(sb->s_root);
    if (sb_info->update_file)
        hypfs_remove(sb_info->update_file);
    kfree(sb->s_fs_info);
    sb->s_fs_info = NULL;
    kill_litter_super(sb);
}

static struct dentry *hypfs_create_file(struct super_block *sb,
                    struct dentry *parent, const char *name,
                    char *data, umode_t mode)
{
    struct dentry *dentry;
    struct inode *inode;

    mutex_lock(&parent->d_inode->i_mutex);
    dentry = lookup_one_len(name, parent, strlen(name));
    if (IS_ERR(dentry)) {
        dentry = ERR_PTR(-ENOMEM);
        goto fail;
    }
    inode = hypfs_make_inode(sb, mode);
    if (!inode) {
        dput(dentry);
        dentry = ERR_PTR(-ENOMEM);
        goto fail;
    }
    if (S_ISREG(mode)) {
        inode->i_fop = &hypfs_file_ops;
        if (data)
            inode->i_size = strlen(data);
        else
            inode->i_size = 0;
    } else if (S_ISDIR(mode)) {
        inode->i_op = &simple_dir_inode_operations;
        inode->i_fop = &simple_dir_operations;
        inc_nlink(parent->d_inode);
    } else
        BUG();
    inode->i_private = data;
    d_instantiate(dentry, inode);
    dget(dentry);
fail:
    mutex_unlock(&parent->d_inode->i_mutex);
    return dentry;
}

struct dentry *hypfs_mkdir(struct super_block *sb, struct dentry *parent,
               const char *name)
{
    struct dentry *dentry;

    dentry = hypfs_create_file(sb, parent, name, NULL, S_IFDIR | DIR_MODE);
    if (IS_ERR(dentry))
        return dentry;
    hypfs_add_dentry(dentry);
    return dentry;
}

static struct dentry *hypfs_create_update_file(struct super_block *sb,
                           struct dentry *dir)
{
    struct dentry *dentry;

    dentry = hypfs_create_file(sb, dir, "update", NULL,
                   S_IFREG | UPDATE_FILE_MODE);
    /*
     * We do not put the update file on the 'delete' list with
     * hypfs_add_dentry(), since it should not be removed when the tree
     * is updated.
     */
    return dentry;
}

struct dentry *hypfs_create_u64(struct super_block *sb, struct dentry *dir,
                const char *name, __u64 value)
{
    char *buffer;
    char tmp[TMP_SIZE];
    struct dentry *dentry;

    snprintf(tmp, TMP_SIZE, "%llu\n", (unsigned long long int)value);
    buffer = kstrdup(tmp, GFP_KERNEL);
    if (!buffer)
        return ERR_PTR(-ENOMEM);
    dentry =
        hypfs_create_file(sb, dir, name, buffer, S_IFREG | REG_FILE_MODE);
    if (IS_ERR(dentry)) {
        kfree(buffer);
        return ERR_PTR(-ENOMEM);
    }
    hypfs_add_dentry(dentry);
    return dentry;
}

struct dentry *hypfs_create_str(struct super_block *sb, struct dentry *dir,
                const char *name, char *string)
{
    char *buffer;
    struct dentry *dentry;

    buffer = kmalloc(strlen(string) + 2, GFP_KERNEL);
    if (!buffer)
        return ERR_PTR(-ENOMEM);
    sprintf(buffer, "%s\n", string);
    dentry =
        hypfs_create_file(sb, dir, name, buffer, S_IFREG | REG_FILE_MODE);
    if (IS_ERR(dentry)) {
        kfree(buffer);
        return ERR_PTR(-ENOMEM);
    }
    hypfs_add_dentry(dentry);
    return dentry;
}

static const struct file_operations hypfs_file_ops = {
    .open       = hypfs_open,
    .release    = hypfs_release,
    .read       = do_sync_read,
    .write      = do_sync_write,
    .aio_read   = hypfs_aio_read,
    .aio_write  = hypfs_aio_write,
    .llseek     = no_llseek,
};

static struct file_system_type hypfs_type = {
    .owner      = THIS_MODULE,
    .name       = "s390_hypfs",
    .mount      = hypfs_mount,
    .kill_sb    = hypfs_kill_super
};

static const struct super_operations hypfs_s_ops = {
    .statfs     = simple_statfs,
    .evict_inode    = hypfs_evict_inode,
    .show_options   = hypfs_show_options,
};

static struct kobject *s390_kobj;

static int __init hypfs_init(void)
{
    int rc;

    rc = hypfs_dbfs_init();
    if (rc)
        return rc;
    if (hypfs_diag_init()) {
        rc = -ENODATA;
        goto fail_dbfs_exit;
    }
    if (hypfs_vm_init()) {
        rc = -ENODATA;
        goto fail_hypfs_diag_exit;
    }
    s390_kobj = kobject_create_and_add("s390", hypervisor_kobj);
    if (!s390_kobj) {
        rc = -ENOMEM;
        goto fail_hypfs_vm_exit;
    }
    rc = register_filesystem(&hypfs_type);
    if (rc)
        goto fail_filesystem;
    return 0;

fail_filesystem:
    kobject_put(s390_kobj);
fail_hypfs_vm_exit:
    hypfs_vm_exit();
fail_hypfs_diag_exit:
    hypfs_diag_exit();
fail_dbfs_exit:
    hypfs_dbfs_exit();
    pr_err("Initialization of hypfs failed with rc=%i\n", rc);
    return rc;
}

static void __exit hypfs_exit(void)
{
    hypfs_diag_exit();
    hypfs_vm_exit();
    hypfs_dbfs_exit();
    unregister_filesystem(&hypfs_type);
    kobject_put(s390_kobj);
}

module_init(hypfs_init)
module_exit(hypfs_exit)

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Michael Holzheu <[email protected]>");
MODULE_DESCRIPTION("s390 Hypervisor Filesystem");