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Sourcecode: fuse version File versions

control.c

/*
  FUSE: Filesystem in Userspace
  Copyright (C) 2001-2006  Miklos Szeredi <miklos@szeredi.hu>

  This program can be distributed under the terms of the GNU GPL.
  See the file COPYING.
*/

#include "fuse_i.h"

#include <linux/init.h>
#include <linux/module.h>

#define FUSE_CTL_SUPER_MAGIC 0x65735543
#ifndef HAVE_I_PRIVATE
#define i_private u.generic_ip
#endif

/*
 * This is non-NULL when the single instance of the control filesystem
 * exists.  Protected by fuse_mutex
 */
static struct super_block *fuse_control_sb;

static struct fuse_conn *fuse_ctl_file_conn_get(struct file *file)
{
      struct fuse_conn *fc;
      mutex_lock(&fuse_mutex);
      fc = file->f_dentry->d_inode->i_private;
      if (fc)
            fc = fuse_conn_get(fc);
      mutex_unlock(&fuse_mutex);
      return fc;
}

static ssize_t fuse_conn_abort_write(struct file *file, const char __user *buf,
                             size_t count, loff_t *ppos)
{
      struct fuse_conn *fc = fuse_ctl_file_conn_get(file);
      if (fc) {
            fuse_abort_conn(fc);
            fuse_conn_put(fc);
      }
      return count;
}

static ssize_t fuse_conn_waiting_read(struct file *file, char __user *buf,
                              size_t len, loff_t *ppos)
{
      char tmp[32];
      size_t size;

      if (!*ppos) {
            struct fuse_conn *fc = fuse_ctl_file_conn_get(file);
            if (!fc)
                  return 0;

            file->private_data=(void *)(long)atomic_read(&fc->num_waiting);
            fuse_conn_put(fc);
      }
      size = sprintf(tmp, "%ld\n", (long)file->private_data);
      return simple_read_from_buffer(buf, len, ppos, tmp, size);
}

static struct file_operations fuse_ctl_abort_ops = {
      .open = nonseekable_open,
      .write = fuse_conn_abort_write,
};

static struct file_operations fuse_ctl_waiting_ops = {
      .open = nonseekable_open,
      .read = fuse_conn_waiting_read,
};

#ifndef KERNEL_2_6_10_PLUS
struct dentry *d_alloc_name(struct dentry *parent, const char *name)
{
      struct qstr q;

      q.name = name;
      q.len = strlen(name);
      q.hash = full_name_hash(q.name, q.len);
      return d_alloc(parent, &q);
}
#endif
static struct dentry *fuse_ctl_add_dentry(struct dentry *parent,
                                struct fuse_conn *fc,
                                const char *name,
                                int mode, int nlink,
                                struct inode_operations *iop,
#ifdef KERNEL_2_6_17_PLUS
                                const struct file_operations *fop
#else
                                struct file_operations *fop
#endif
)
{
      struct dentry *dentry;
      struct inode *inode;

      BUG_ON(fc->ctl_ndents >= FUSE_CTL_NUM_DENTRIES);
      dentry = d_alloc_name(parent, name);
      if (!dentry)
            return NULL;

      fc->ctl_dentry[fc->ctl_ndents++] = dentry;
      inode = new_inode(fuse_control_sb);
      if (!inode)
            return NULL;

      inode->i_mode = mode;
      inode->i_uid = fc->user_id;
      inode->i_gid = fc->group_id;
      inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
      /* setting ->i_op to NULL is not allowed */
      if (iop)
            inode->i_op = iop;
      inode->i_fop = fop;
      inode->i_nlink = nlink;
      inode->i_private = fc;
      d_add(dentry, inode);
      return dentry;
}

/*
 * Add a connection to the control filesystem (if it exists).  Caller
 * must hold fuse_mutex
 */
int fuse_ctl_add_conn(struct fuse_conn *fc)
{
      struct dentry *parent;
      char name[32];

      if (!fuse_control_sb)
            return 0;

      parent = fuse_control_sb->s_root;
      inc_nlink(parent->d_inode);
      sprintf(name, "%llu", (unsigned long long) fc->id);
      parent = fuse_ctl_add_dentry(parent, fc, name, S_IFDIR | 0500, 2,
                             &simple_dir_inode_operations,
                             &simple_dir_operations);
      if (!parent)
            goto err;

      if (!fuse_ctl_add_dentry(parent, fc, "waiting", S_IFREG | 0400, 1,
                        NULL, &fuse_ctl_waiting_ops) ||
          !fuse_ctl_add_dentry(parent, fc, "abort", S_IFREG | 0200, 1,
                         NULL, &fuse_ctl_abort_ops))
            goto err;

      return 0;

 err:
      fuse_ctl_remove_conn(fc);
      return -ENOMEM;
}

/*
 * Remove a connection from the control filesystem (if it exists).
 * Caller must hold fuse_mutex
 */
void fuse_ctl_remove_conn(struct fuse_conn *fc)
{
      int i;

      if (!fuse_control_sb)
            return;

      for (i = fc->ctl_ndents - 1; i >= 0; i--) {
            struct dentry *dentry = fc->ctl_dentry[i];
            dentry->d_inode->i_private = NULL;
            d_drop(dentry);
            dput(dentry);
      }
      fuse_control_sb->s_root->d_inode->i_nlink--;
}

static int fuse_ctl_fill_super(struct super_block *sb, void *data, int silent)
{
      struct tree_descr empty_descr = {""};
      struct fuse_conn *fc;
      int err;

      err = simple_fill_super(sb, FUSE_CTL_SUPER_MAGIC, &empty_descr);
      if (err)
            return err;

      mutex_lock(&fuse_mutex);
      BUG_ON(fuse_control_sb);
      fuse_control_sb = sb;
      list_for_each_entry(fc, &fuse_conn_list, entry) {
            err = fuse_ctl_add_conn(fc);
            if (err) {
                  fuse_control_sb = NULL;
                  mutex_unlock(&fuse_mutex);
                  return err;
            }
      }
      mutex_unlock(&fuse_mutex);

      return 0;
}

#ifdef KERNEL_2_6_18_PLUS
static int fuse_ctl_get_sb(struct file_system_type *fs_type, int flags,
                  const char *dev_name, void *raw_data,
                  struct vfsmount *mnt)
{
      return get_sb_single(fs_type, flags, raw_data,
                        fuse_ctl_fill_super, mnt);
}
#else
static struct super_block *fuse_ctl_get_sb(struct file_system_type *fs_type,
                                 int flags, const char *dev_name,
                                 void *raw_data)
{
      return get_sb_single(fs_type, flags, raw_data, fuse_ctl_fill_super);
}
#endif

static void fuse_ctl_kill_sb(struct super_block *sb)
{
      struct fuse_conn *fc;

      mutex_lock(&fuse_mutex);
      fuse_control_sb = NULL;
      list_for_each_entry(fc, &fuse_conn_list, entry)
            fc->ctl_ndents = 0;
      mutex_unlock(&fuse_mutex);

      kill_litter_super(sb);
}

static struct file_system_type fuse_ctl_fs_type = {
      .owner            = THIS_MODULE,
      .name       = "fusectl",
      .get_sb           = fuse_ctl_get_sb,
      .kill_sb    = fuse_ctl_kill_sb,
};

int __init fuse_ctl_init(void)
{
      return register_filesystem(&fuse_ctl_fs_type);
}

void fuse_ctl_cleanup(void)
{
      unregister_filesystem(&fuse_ctl_fs_type);
}

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