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inode.c

/*
 *  arch/s390/hypfs/inode.c
 *    Hypervisor filesystem for Linux on s390.
 *
 *    Copyright (C) IBM Corp. 2006
 *    Author(s): Michael Holzheu <holzheu@de.ibm.com>
 */

#include <linux/types.h>
#include <linux/errno.h>
#include <linux/fs.h>
#include <linux/namei.h>
#include <linux/vfs.h>
#include <linux/pagemap.h>
#include <linux/gfp.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 {
      uid_t uid;              /* uid used for files and dirs */
      gid_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 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;
      if (!parent || !parent->d_inode)
            return;
      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, int mode)
{
      struct inode *ret = new_inode(sb);

      if (ret) {
            struct hypfs_sb_info *hypfs_info = sb->s_fs_info;
            ret->i_mode = mode;
            ret->i_uid = hypfs_info->uid;
            ret->i_gid = hypfs_info->gid;
            ret->i_blocks = 0;
            ret->i_atime = ret->i_mtime = ret->i_ctime = CURRENT_TIME;
            if (mode & S_IFDIR)
                  ret->i_nlink = 2;
            else
                  ret->i_nlink = 1;
      }
      return ret;
}

static void hypfs_drop_inode(struct inode *inode)
{
      kfree(inode->i_private);
      generic_delete_inode(inode);
}

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 0;
}

static ssize_t hypfs_aio_read(struct kiocb *iocb, const struct iovec *iov,
                        unsigned long nr_segs, loff_t offset)
{
      char *data;
      size_t len;
      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) {
            count = -EINVAL;
            goto out;
      }

      data = filp->private_data;
      len = strlen(data);
      if (offset > len) {
            count = 0;
            goto out;
      }
      if (count > len - offset)
            count = len - offset;
      if (copy_to_user(buf, data + offset, count)) {
            count = -EFAULT;
            goto out;
      }
      iocb->ki_pos += count;
      file_accessed(filp);
out:
      return count;
}
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) {
            printk(KERN_ERR "hypfs: Update 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 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];

      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;
                  hypfs_info->uid = option;
                  break;
            case opt_gid:
                  if (match_int(&args[0], &option))
                        return -EINVAL;
                  hypfs_info->gid = option;
                  break;
            case opt_err:
            default:
                  printk(KERN_ERR "hypfs: Unrecognized mount option "
                         "\"%s\" or missing value\n", str);
                  return -EINVAL;
            }
      }
      return 0;
}

static int hypfs_show_options(struct seq_file *s, struct vfsmount *mnt)
{
      struct hypfs_sb_info *hypfs_info = mnt->mnt_sb->s_fs_info;

      seq_printf(s, ",uid=%u", hypfs_info->uid);
      seq_printf(s, ",gid=%u", 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)) {
            rc = -EINVAL;
            goto err_alloc;
      }
      root_inode = hypfs_make_inode(sb, S_IFDIR | 0755);
      if (!root_inode) {
            rc = -ENOMEM;
            goto err_alloc;
      }
      root_inode->i_op = &simple_dir_inode_operations;
      root_inode->i_fop = &simple_dir_operations;
      root_dentry = d_alloc_root(root_inode);
      if (!root_dentry) {
            iput(root_inode);
            rc = -ENOMEM;
            goto err_alloc;
      }
      if (MACHINE_IS_VM)
            rc = hypfs_vm_create_files(sb, root_dentry);
      else
            rc = hypfs_diag_create_files(sb, root_dentry);
      if (rc)
            goto err_tree;
      sbi->update_file = hypfs_create_update_file(sb, root_dentry);
      if (IS_ERR(sbi->update_file)) {
            rc = PTR_ERR(sbi->update_file);
            goto err_tree;
      }
      hypfs_update_update(sb);
      sb->s_root = root_dentry;
      printk(KERN_INFO "hypfs: Hypervisor filesystem mounted\n");
      return 0;

err_tree:
      hypfs_delete_tree(root_dentry);
      d_genocide(root_dentry);
      dput(root_dentry);
err_alloc:
      kfree(sbi);
      return rc;
}

static int hypfs_get_super(struct file_system_type *fst, int flags,
                  const char *devname, void *data, struct vfsmount *mnt)
{
      return get_sb_single(fst, flags, data, hypfs_fill_super, mnt);
}

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);
            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, mode_t mode)
{
      struct dentry *dentry;
      struct inode *inode;
      struct qstr qname;

      qname.name = name;
      qname.len = strlen(name);
      qname.hash = full_name_hash(name, qname.len);
      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 (mode & S_IFREG) {
            inode->i_fop = &hypfs_file_ops;
            if (data)
                  inode->i_size = strlen(data);
            else
                  inode->i_size = 0;
      } else if (mode & S_IFDIR) {
            inode->i_op = &simple_dir_inode_operations;
            inode->i_fop = &simple_dir_operations;
            parent->d_inode->i_nlink++;
      } 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, "%lld\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,
};

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

static struct super_operations hypfs_s_ops = {
      .statfs           = simple_statfs,
      .drop_inode = hypfs_drop_inode,
      .show_options     = hypfs_show_options,
};

static decl_subsys(s390, NULL, NULL);

static int __init hypfs_init(void)
{
      int rc;

      if (MACHINE_IS_VM) {
            if (hypfs_vm_init())
                  /* no diag 2fc, just exit */
                  return -ENODATA;
      } else {
            if (hypfs_diag_init()) {
                  rc = -ENODATA;
                  goto fail_diag;
            }
      }
      kobj_set_kset_s(&s390_subsys, hypervisor_subsys);
      rc = subsystem_register(&s390_subsys);
      if (rc)
            goto fail_sysfs;
      rc = register_filesystem(&hypfs_type);
      if (rc)
            goto fail_filesystem;
      return 0;

fail_filesystem:
      subsystem_unregister(&s390_subsys);
fail_sysfs:
      if (!MACHINE_IS_VM)
            hypfs_diag_exit();
fail_diag:
      printk(KERN_ERR "hypfs: Initialization failed with rc = %i.\n", rc);
      return rc;
}

static void __exit hypfs_exit(void)
{
      if (!MACHINE_IS_VM)
            hypfs_diag_exit();
      unregister_filesystem(&hypfs_type);
      subsystem_unregister(&s390_subsys);
}

module_init(hypfs_init)
module_exit(hypfs_exit)

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Michael Holzheu <holzheu@de.ibm.com>");
MODULE_DESCRIPTION("s390 Hypervisor Filesystem");

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