path: root/fs/fuse/dev.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>
#include <linux/poll.h>
#include <linux/uio.h>
#include <linux/miscdevice.h>
#include <linux/pagemap.h>
#include <linux/file.h>
#include <linux/slab.h>

MODULE_ALIAS_MISCDEV(FUSE_MINOR);

static kmem_cache_t *fuse_req_cachep;

static struct fuse_conn *fuse_get_conn(struct file *file)
{
	/*
	 * Lockless access is OK, because file->private data is set
	 * once during mount and is valid until the file is released.
	 */
	return file->private_data;
}

static void fuse_request_init(struct fuse_req *req)
{
	memset(req, 0, sizeof(*req));
	INIT_LIST_HEAD(&req->list);
	init_waitqueue_head(&req->waitq);
	atomic_set(&req->count, 1);
}

struct fuse_req *fuse_request_alloc(void)
{
	struct fuse_req *req = kmem_cache_alloc(fuse_req_cachep, SLAB_KERNEL);
	if (req)
		fuse_request_init(req);
	return req;
}

void fuse_request_free(struct fuse_req *req)
{
	kmem_cache_free(fuse_req_cachep, req);
}

static void block_sigs(sigset_t *oldset)
{
	sigset_t mask;

	siginitsetinv(&mask, sigmask(SIGKILL));
	sigprocmask(SIG_BLOCK, &mask, oldset);
}

static void restore_sigs(sigset_t *oldset)
{
	sigprocmask(SIG_SETMASK, oldset, NULL);
}

static void __fuse_get_request(struct fuse_req *req)
{
	atomic_inc(&req->count);
}

/* Must be called with > 1 refcount */
static void __fuse_put_request(struct fuse_req *req)
{
	BUG_ON(atomic_read(&req->count) < 2);
	atomic_dec(&req->count);
}

struct fuse_req *fuse_get_req(struct fuse_conn *fc)
{
	struct fuse_req *req;
	sigset_t oldset;
	int intr;
	int err;

	atomic_inc(&fc->num_waiting);
	block_sigs(&oldset);
	intr = wait_event_interruptible(fc->blocked_waitq, !fc->blocked);
	restore_sigs(&oldset);
	err = -EINTR;
	if (intr)
		goto out;

	err = -ENOTCONN;
	if (!fc->connected)
		goto out;

	req = fuse_request_alloc();
	err = -ENOMEM;
	if (!req)
		goto out;

	req->in.h.uid = current->fsuid;
	req->in.h.gid = current->fsgid;
	req->in.h.pid = current->pid;
	req->waiting = 1;
	return req;

 out:
	atomic_dec(&fc->num_waiting);
	return ERR_PTR(err);
}

void fuse_put_request(struct fuse_conn *fc, struct fuse_req *req)
{
	if (atomic_dec_and_test(&req->count)) {
		if (req->waiting)
			atomic_dec(&fc->num_waiting);
		fuse_request_free(req);
	}
}

/*
 * This function is called when a request is finished.  Either a reply
 * has arrived or it was interrupted (and not yet sent) or some error
 * occurred during communication with userspace, or the device file
 * was closed.  The requester thread is woken up (if still waiting),
 * the 'end' callback is called if given, else the reference to the
 * request is released
 *
 * Called with fc->lock, unlocks it
 */
static void request_end(struct fuse_conn *fc, struct fuse_req *req)
{
	void (*end) (struct fuse_conn *, struct fuse_req *) = req->end;
	req->end = NULL;
	list_del(&req->list);
	req->state = FUSE_REQ_FINISHED;
	if (req->background) {
		if (fc->num_background == FUSE_MAX_BACKGROUND) {
			fc->blocked = 0;
			wake_up_all(&fc->blocked_waitq);
		}
		fc->num_background--;
	}
	spin_unlock(&fc->lock);
	dput(req->dentry);
	mntput(req->vfsmount);
	if (req->file)
		fput(req->file);
	wake_up(&req->waitq);
	if (end)
		end(fc, req);
	else
		fuse_put_request(fc, req);
}

/* Called with fc->lock held.  Releases, and then reacquires it. */
static void request_wait_answer(struct fuse_conn *fc, struct fuse_req *req)
{
	sigset_t oldset;

	spin_unlock(&fc->lock);
	if (req->force)
		wait_event(req->waitq, req->state == FUSE_REQ_FINISHED);
	else {
		block_sigs(&oldset);
		wait_event_interruptible(req->waitq,
					 req->state == FUSE_REQ_FINISHED);
		restore_sigs(&oldset);
	}
	spin_lock(&fc->lock);
	if (req->state == FUSE_REQ_FINISHED && !req->interrupted)
		return;

	if (!req->interrupted) {
		req->out.h.error = -EINTR;
		req->interrupted = 1;
	}
	if (req->locked) {