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/*
  FUSE: Filesystem in Userspace
  Copyright (C) 2001-2005  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;

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static struct fuse_conn *fuse_get_conn(struct file *file)
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{
	struct fuse_conn *fc;
	spin_lock(&fuse_lock);
	fc = file->private_data;
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	if (fc && !fc->connected)
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		fc = NULL;
	spin_unlock(&fuse_lock);
	return fc;
}

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static void fuse_request_init(struct fuse_req *req)
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{
	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);
}

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

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

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

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/*
 * Reset request, so that it can be reused
 *
 * The caller must be _very_ careful to make sure, that it is holding
 * the only reference to req
 */
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void fuse_reset_request(struct fuse_req *req)
{
	int preallocated = req->preallocated;
	BUG_ON(atomic_read(&req->count) != 1);
	fuse_request_init(req);
	req->preallocated = preallocated;
}

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);
}

static struct fuse_req *do_get_request(struct fuse_conn *fc)
{
	struct fuse_req *req;

	spin_lock(&fuse_lock);
	BUG_ON(list_empty(&fc->unused_list));
	req = list_entry(fc->unused_list.next, struct fuse_req, list);
	list_del_init(&req->list);
	spin_unlock(&fuse_lock);
	fuse_request_init(req);
	req->preallocated = 1;
	req->in.h.uid = current->fsuid;
	req->in.h.gid = current->fsgid;
	req->in.h.pid = current->pid;
	return req;
}

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/* This can return NULL, but only in case it's interrupted by a SIGKILL */
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struct fuse_req *fuse_get_request(struct fuse_conn *fc)
{
	int intr;
	sigset_t oldset;

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	atomic_inc(&fc->num_waiting);
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	block_sigs(&oldset);
	intr = down_interruptible(&fc->outstanding_sem);
	restore_sigs(&oldset);
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	if (intr) {
		atomic_dec(&fc->num_waiting);
		return NULL;
	}
	return do_get_request(fc);
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}

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/* Must be called with fuse_lock held */
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static void fuse_putback_request(struct fuse_conn *fc, struct fuse_req *req)
{
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	if (req->preallocated) {
		atomic_dec(&fc->num_waiting);
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		list_add(&req->list, &fc->unused_list);
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	} else
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		fuse_request_free(req);

	/* If we are in debt decrease that first */
	if (fc->outstanding_debt)
		fc->outstanding_debt--;
	else
		up(&fc->outstanding_sem);
}

void fuse_put_request(struct fuse_conn *fc, struct fuse_req *req)
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{
	if (atomic_dec_and_test(&req->count)) {
		spin_lock(&fuse_lock);
		fuse_putback_request(fc, req);
		spin_unlock(&fuse_lock);
	}
}

static void fuse_put_request_locked(struct fuse_conn *fc, struct fuse_req *req)
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{
	if (atomic_dec_and_test(&req->count))
		fuse_putback_request(fc, req);
}

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void fuse_release_background(struct fuse_req *req)
{
	iput(req->inode);
	iput(req->inode2);
	if (req->file)
		fput(req->file);
	spin_lock(&fuse_lock);
	list_del(&req->bg_entry);
	spin_unlock(&fuse_lock);
}

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/*
 * 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
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 * occurred during communication with userspace, or the device file
 * was closed.  In case of a background request the reference to the
 * stored objects are released.  The requester thread is woken up (if
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 * still waiting), the 'end' callback is called if given, else the
 * reference to the request is released
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 *
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 * Releasing extra reference for foreground requests must be done
 * within the same locked region as setting state to finished.  This
 * is because fuse_reset_request() may be called after request is
 * finished and it must be the sole possessor.  If request is
 * interrupted and put in the background, it will return with an error
 * and hence never be reset and reused.
 *
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 * Called with fuse_lock, unlocks it
 */
static void request_end(struct fuse_conn *fc, struct fuse_req *req)
{
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	list_del(&req->list);
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	req->state = FUSE_REQ_FINISHED;
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	if (!req->background) {
		wake_up(&req->waitq);
		fuse_put_request_locked(fc, req);
		spin_unlock(&fuse_lock);
	} else {
		void (*end) (struct fuse_conn *, struct fuse_req *) = req->end;
		req->end = NULL;
		spin_unlock(&fuse_lock);
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		down_read(&fc->sbput_sem);
		if (fc->mounted)
			fuse_release_background(req);
		up_read(&fc->sbput_sem);
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		if (end)
			end(fc, req);
		else
			fuse_put_request(fc, req);
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	}
}

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/*
 * Unfortunately request interruption not just solves the deadlock
 * problem, it causes problems too.  These stem from the fact, that an
 * interrupted request is continued to be processed in userspace,
 * while all the locks and object references (inode and file) held
 * during the operation are released.
 *
 * To release the locks is exactly why there's a need to interrupt the
 * request, so there's not a lot that can be done about this, except
 * introduce additional locking in userspace.
 *
 * More important is to keep inode and file references until userspace
 * has replied, otherwise FORGET and RELEASE could be sent while the
 * inode/file is still used by the filesystem.
 *
 * For this reason the concept of "background" request is introduced.
 * An interrupted request is backgrounded if it has been already sent
 * to userspace.  Backgrounding involves getting an extra reference to
 * inode(s) or file used in the request, and adding the request to
 * fc->background list.  When a reply is received for a background
 * request, the object references are released, and the request is
 * removed from the list.  If the filesystem is unmounted while there
 * are still background requests, the list is walked and references
 * are released as if a reply was received.
 *
 * There's one more use for a background request.  The RELEASE message is
 * always sent as background, since it doesn't return an error or
 * data.
 */
static void background_request(struct fuse_conn *fc, struct fuse_req *req)
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{
	req->background = 1;
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	list_add(&req->bg_entry, &fc->background);
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	if (req->inode)
		req->inode = igrab(req->inode);
	if (req->inode2)
		req->inode2 = igrab(req->inode2);
	if (req->file)
		get_file(req->file);
}

/* Called with fuse_lock held.  Releases, and then reacquires it. */
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static void request_wait_answer(struct fuse_conn *fc, struct fuse_req *req)
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{
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	sigset_t oldset;
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	spin_unlock(&fuse_lock);
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	block_sigs(&oldset);
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	wait_event_interruptible(req->waitq, req->state == FUSE_REQ_FINISHED);
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	restore_sigs(&oldset);
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	spin_lock(&fuse_lock);
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	if (req->state == FUSE_REQ_FINISHED && !req->interrupted)
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		return;

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	if (!req->interrupted) {
		req->out.h.error = -EINTR;
		req->interrupted = 1;
	}
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	if (req->locked) {
		/* This is uninterruptible sleep, because data is
		   being copied to/from the buffers of req.  During
		   locked state, there mustn't be any filesystem
		   operation (e.g. page fault), since that could lead
		   to deadlock */
		spin_unlock(&fuse_lock);
		wait_event(req->waitq, !req->locked);
		spin_lock(&fuse_lock);
	}
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	if (req->state == FUSE_REQ_PENDING) {
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		list_del(&req->list);
		__fuse_put_request(req);
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	} else if (req->state == FUSE_REQ_SENT)
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		background_request(fc, req);
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}

static unsigned len_args(unsigned numargs, struct fuse_arg *args)
{
	unsigned nbytes = 0;
	unsigned i;

	for (i = 0; i < numargs; i++)
		nbytes += args[i].size;

	return nbytes;
}

static void queue_request(struct fuse_conn *fc, struct fuse_req *req)
{
	fc->reqctr++;
	/* zero is special */
	if (fc->reqctr == 0)
		fc->reqctr = 1;
	req->in.h.unique = fc->reqctr;
	req->in.h.len = sizeof(struct fuse_in_header) +
		len_args(req->in.numargs, (struct fuse_arg *) req->in.args);
	if (!req->preallocated) {
		/* If request is not preallocated (either FORGET or
		   RELEASE), then still decrease outstanding_sem, so
		   user can't open infinite number of files while not
		   processing the RELEASE requests.  However for
		   efficiency do it without blocking, so if down()
		   would block, just increase the debt instead */
		if (down_trylock(&fc->outstanding_sem))
			fc->outstanding_debt++;
	}
	list_add_tail(&req->list, &fc->pending);
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	req->state = FUSE_REQ_PENDING;
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	wake_up(&fc->waitq);
}

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/*
 * This can only be interrupted by a SIGKILL
 */
void request_send(struct fuse_conn *fc, struct fuse_req *req)
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{
	req->isreply = 1;
	spin_lock(&fuse_lock);
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	if (!fc->connected)
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		req->out.h.error = -ENOTCONN;
	else if (fc->conn_error)
		req->out.h.error = -ECONNREFUSED;
	else {
		queue_request(fc, req);
		/* acquire extra reference, since request is still needed
		   after request_end() */
		__fuse_get_request(req);

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		request_wait_answer(fc, req);
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	}
	spin_unlock(&fuse_lock);
}

static void request_send_nowait(struct fuse_conn *fc, struct fuse_req *req)
{
	spin_lock(&fuse_lock);
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	if (fc->connected) {
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		queue_request(fc, req);
		spin_unlock(&fuse_lock);
	} else {
		req->out.h.error = -ENOTCONN;
		request_end(fc, req);
	}
}

void request_send_noreply(struct fuse_conn *fc, struct fuse_req *req)
{
	req->isreply = 0;
	request_send_nowait(fc, req);
}

void request_send_background(struct fuse_conn *fc, struct fuse_req *req)
{
	req->isreply = 1;
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	spin_lock(&fuse_lock);
	background_request(fc, req);
	spin_unlock(&fuse_lock);
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	request_send_nowait(fc, req);
}

/*
 * Lock the request.  Up to the next unlock_request() there mustn't be
 * anything that could cause a page-fault.  If the request was already
 * interrupted bail out.
 */
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static int lock_request(struct fuse_req *req)
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{
	int err = 0;
	if (req) {
		spin_lock(&fuse_lock);
		if (req->interrupted)
			err = -ENOENT;
		else
			req->locked = 1;
		spin_unlock(&fuse_lock);
	}
	return err;
}

/*
 * Unlock request.  If it was interrupted during being locked, the
 * requester thread is currently waiting for it to be unlocked, so
 * wake it up.
 */
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static void unlock_request(struct fuse_req *req)
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{
	if (req) {
		spin_lock(&fuse_lock);
		req->locked = 0;
		if (req->interrupted)
			wake_up(&req->waitq);
		spin_unlock(&fuse_lock);
	}
}

struct fuse_copy_state {
	int write;
	struct fuse_req *req;
	const struct iovec *iov;
	unsigned long nr_segs;
	unsigned long seglen;
	unsigned long addr;
	struct page *pg;
	void *mapaddr;
	void *buf;
	unsigned len;
};

static void fuse_copy_init(struct fuse_copy_state *cs, int write,
			   struct fuse_req *req, const struct iovec *iov,
			   unsigned long nr_segs)
{
	memset(cs, 0, sizeof(*cs));
	cs->write = write;
	cs->req = req;
	cs->iov = iov;
	cs->nr_segs = nr_segs;
}

/* Unmap and put previous page of userspace buffer */
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static void fuse_copy_finish(struct fuse_copy_state *cs)
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{
	if (cs->mapaddr) {
		kunmap_atomic(cs->mapaddr, KM_USER0);
		if (cs->write) {
			flush_dcache_page(cs->pg);
			set_page_dirty_lock(cs->pg);
		}
		put_page(cs->pg);
		cs->mapaddr = NULL;
	}
}

/*
 * Get another pagefull of userspace buffer, and map it to kernel
 * address space, and lock request
 */
static int fuse_copy_fill(struct fuse_copy_state *cs)
{
	unsigned long offset;
	int err;

	unlock_request(cs->req);
	fuse_copy_finish(cs);
	if (!cs->seglen) {
		BUG_ON(!cs->nr_segs);
		cs->seglen = cs->iov[0].iov_len;
		cs->addr = (unsigned long) cs->iov[0].iov_base;
		cs->iov ++;
		cs->nr_segs --;
	}
	down_read(&current->mm->mmap_sem);
	err = get_user_pages(current, current->mm, cs->addr, 1, cs->write, 0,
			     &cs->pg, NULL);
	up_read(&current->mm->mmap_sem);
	if (err < 0)
		return err;
	BUG_ON(err != 1);
	offset = cs->addr % PAGE_SIZE;
	cs->mapaddr = kmap_atomic(cs->pg, KM_USER0);
	cs->buf = cs->mapaddr + offset;
	cs->len = min(PAGE_SIZE - offset, cs->seglen);
	cs->seglen -= cs->len;
	cs->addr += cs->len;

	return lock_request(cs->req);
}

/* Do as much copy to/from userspace buffer as we can */
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static int fuse_copy_do(struct fuse_copy_state *cs, void **val, unsigned *size)
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{
	unsigned ncpy = min(*size, cs->len);
	if (val) {
		if (cs->write)
			memcpy(cs->buf, *val, ncpy);
		else
			memcpy(*val, cs->buf, ncpy);
		*val += ncpy;
	}
	*size -= ncpy;
	cs->len -= ncpy;
	cs->buf += ncpy;
	return ncpy;
}

/*
 * Copy a page in the request to/from the userspace buffer.  Must be
 * done atomically
 */
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static int fuse_copy_page(struct fuse_copy_state *cs, struct page *page,
			  unsigned offset, unsigned count, int zeroing)
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{
	if (page && zeroing && count < PAGE_SIZE) {
		void *mapaddr = kmap_atomic(page, KM_USER1);
		memset(mapaddr, 0, PAGE_SIZE);
		kunmap_atomic(mapaddr, KM_USER1);
	}
	while (count) {
		int err;
		if (!cs->len && (err = fuse_copy_fill(cs)))
			return err;
		if (page) {
			void *mapaddr = kmap_atomic(page, KM_USER1);
			void *buf = mapaddr + offset;
			offset += fuse_copy_do(cs, &buf, &count);
			kunmap_atomic(mapaddr, KM_USER1);
		} else
			offset += fuse_copy_do(cs, NULL, &count);
	}
	if (page && !cs->write)
		flush_dcache_page(page);
	return 0;
}

/* Copy pages in the request to/from userspace buffer */
static int fuse_copy_pages(struct fuse_copy_state *cs, unsigned nbytes,
			   int zeroing)
{
	unsigned i;
	struct fuse_req *req = cs->req;
	unsigned offset = req->page_offset;
	unsigned count = min(nbytes, (unsigned) PAGE_SIZE - offset);

	for (i = 0; i < req->num_pages && (nbytes || zeroing); i++) {
		struct page *page = req->pages[i];
		int err = fuse_copy_page(cs, page, offset, count, zeroing);
		if (err)
			return err;

		nbytes -= count;
		count = min(nbytes, (unsigned) PAGE_SIZE);
		offset = 0;
	}
	return 0;
}

/* Copy a single argument in the request to/from userspace buffer */
static int fuse_copy_one(struct fuse_copy_state *cs, void *val, unsigned size)
{
	while (size) {
		int err;
		if (!cs->len && (err = fuse_copy_fill(cs)))
			return err;
		fuse_copy_do(cs, &val, &size);
	}
	return 0;
}

/* Copy request arguments to/from userspace buffer */
static int fuse_copy_args(struct fuse_copy_state *cs, unsigned numargs,
			  unsigned argpages, struct fuse_arg *args,
			  int zeroing)
{
	int err = 0;
	unsigned i;

	for (i = 0; !err && i < numargs; i++)  {
		struct fuse_arg *arg = &args[i];
		if (i == numargs - 1 && argpages)
			err = fuse_copy_pages(cs, arg->size, zeroing);
		else
			err = fuse_copy_one(cs, arg->value, arg->size);
	}
	return err;
}

/* Wait until a request is available on the pending list */
static void request_wait(struct fuse_conn *fc)
{
	DECLARE_WAITQUEUE(wait, current);

	add_wait_queue_exclusive(&fc->waitq, &wait);
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	while (fc->connected && list_empty(&fc->pending)) {
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		set_current_state(TASK_INTERRUPTIBLE);
		if (signal_pending(current))
			break;

		spin_unlock(&fuse_lock);
		schedule();
		spin_lock(&fuse_lock);
	}
	set_current_state(TASK_RUNNING);
	remove_wait_queue(&fc->waitq, &wait);
}

/*
 * Read a single request into the userspace filesystem's buffer.  This
 * function waits until a request is available, then removes it from
 * the pending list and copies request data to userspace buffer.  If
 * no reply is needed (FORGET) or request has been interrupted or
 * there was an error during the copying then it's finished by calling
 * request_end().  Otherwise add it to the processing list, and set
 * the 'sent' flag.
 */
static ssize_t fuse_dev_readv(struct file *file, const struct iovec *iov,
			      unsigned long nr_segs, loff_t *off)
{
	int err;
	struct fuse_conn *fc;
	struct fuse_req *req;
	struct fuse_in *in;
	struct fuse_copy_state cs;
	unsigned reqsize;

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	spin_lock(&fuse_lock);
	fc = file->private_data;
	err = -EPERM;
	if (!fc)
		goto err_unlock;
	request_wait(fc);
	err = -ENODEV;
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	if (!fc->connected)
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		goto err_unlock;
	err = -ERESTARTSYS;
	if (list_empty(&fc->pending))
		goto err_unlock;

	req = list_entry(fc->pending.next, struct fuse_req, list);
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	req->state = FUSE_REQ_READING;
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	list_move(&req->list, &fc->io);
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	in = &req->in;
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	reqsize = in->h.len;
	/* If request is too large, reply with an error and restart the read */
	if (iov_length(iov, nr_segs) < reqsize) {
		req->out.h.error = -EIO;
		/* SETXATTR is special, since it may contain too large data */
		if (in->h.opcode == FUSE_SETXATTR)
			req->out.h.error = -E2BIG;
		request_end(fc, req);
		goto restart;
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	}
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	spin_unlock(&fuse_lock);
	fuse_copy_init(&cs, 1, req, iov, nr_segs);
	err = fuse_copy_one(&cs, &in->h, sizeof(in->h));
	if (!err)
		err = fuse_copy_args(&cs, in->numargs, in->argpages,
				     (struct fuse_arg *) in->args, 0);
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	fuse_copy_finish(&cs);
	spin_lock(&fuse_lock);
	req->locked = 0;
	if (!err && req->interrupted)
		err = -ENOENT;
	if (err) {
		if (!req->interrupted)
			req->out.h.error = -EIO;
		request_end(fc, req);
		return err;
	}
	if (!req->isreply)
		request_end(fc, req);
	else {
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		req->state = FUSE_REQ_SENT;
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		list_move_tail(&req->list, &fc->processing);
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		spin_unlock(&fuse_lock);
	}
	return reqsize;

 err_unlock:
	spin_unlock(&fuse_lock);
	return err;
}

static ssize_t fuse_dev_read(struct file *file, char __user *buf,
			     size_t nbytes, loff_t *off)
{
	struct iovec iov;
	iov.iov_len = nbytes;
	iov.iov_base = buf;
	return fuse_dev_readv(file, &iov, 1, off);
}

/* Look up request on processing list by unique ID */
static struct fuse_req *request_find(struct fuse_conn *fc, u64 unique)
{
	struct list_head *entry;

	list_for_each(entry, &fc->processing) {
		struct fuse_req *req;
		req = list_entry(entry, struct fuse_req, list);
		if (req->in.h.unique == unique)
			return req;
	}
	return NULL;
}

static int copy_out_args(struct fuse_copy_state *cs, struct fuse_out *out,
			 unsigned nbytes)
{
	unsigned reqsize = sizeof(struct fuse_out_header);

	if (out->h.error)
		return nbytes != reqsize ? -EINVAL : 0;

	reqsize += len_args(out->numargs, out->args);

	if (reqsize < nbytes || (reqsize > nbytes && !out->argvar))
		return -EINVAL;
	else if (reqsize > nbytes) {
		struct fuse_arg *lastarg = &out->args[out->numargs-1];
		unsigned diffsize = reqsize - nbytes;
		if (diffsize > lastarg->size)
			return -EINVAL;
		lastarg->size -= diffsize;
	}
	return fuse_copy_args(cs, out->numargs, out->argpages, out->args,
			      out->page_zeroing);
}

/*
 * Write a single reply to a request.  First the header is copied from
 * the write buffer.  The request is then searched on the processing
 * list by the unique ID found in the header.  If found, then remove
 * it from the list and copy the rest of the buffer to the request.
 * The request is finished by calling request_end()
 */
static ssize_t fuse_dev_writev(struct file *file, const struct iovec *iov,
			       unsigned long nr_segs, loff_t *off)
{
	int err;
	unsigned nbytes = iov_length(iov, nr_segs);
	struct fuse_req *req;
	struct fuse_out_header oh;
	struct fuse_copy_state cs;
	struct fuse_conn *fc = fuse_get_conn(file);
	if (!fc)
		return -ENODEV;

	fuse_copy_init(&cs, 0, NULL, iov, nr_segs);
	if (nbytes < sizeof(struct fuse_out_header))
		return -EINVAL;

	err = fuse_copy_one(&cs, &oh, sizeof(oh));
	if (err)
		goto err_finish;
	err = -EINVAL;
	if (!oh.unique || oh.error <= -1000 || oh.error > 0 ||
	    oh.len != nbytes)
		goto err_finish;

	spin_lock(&fuse_lock);
753 754 755 756
	err = -ENOENT;
	if (!fc->connected)
		goto err_unlock;

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	req = request_find(fc, oh.unique);
	err = -EINVAL;
	if (!req)
		goto err_unlock;

	if (req->interrupted) {
763
		spin_unlock(&fuse_lock);
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		fuse_copy_finish(&cs);
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		spin_lock(&fuse_lock);
		request_end(fc, req);
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		return -ENOENT;
	}
769
	list_move(&req->list, &fc->io);
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	req->out.h = oh;
	req->locked = 1;
	cs.req = req;
	spin_unlock(&fuse_lock);

	err = copy_out_args(&cs, &req->out, nbytes);
	fuse_copy_finish(&cs);

	spin_lock(&fuse_lock);
	req->locked = 0;
	if (!err) {
		if (req->interrupted)
			err = -ENOENT;
	} else if (!req->interrupted)
		req->out.h.error = -EIO;
	request_end(fc, req);

	return err ? err : nbytes;

 err_unlock:
	spin_unlock(&fuse_lock);
 err_finish:
	fuse_copy_finish(&cs);
	return err;
}

static ssize_t fuse_dev_write(struct file *file, const char __user *buf,
			      size_t nbytes, loff_t *off)
{
	struct iovec iov;
	iov.iov_len = nbytes;
	iov.iov_base = (char __user *) buf;
	return fuse_dev_writev(file, &iov, 1, off);
}

static unsigned fuse_dev_poll(struct file *file, poll_table *wait)
{
	unsigned mask = POLLOUT | POLLWRNORM;
808
	struct fuse_conn *fc = fuse_get_conn(file);
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	if (!fc)
810
		return POLLERR;
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	poll_wait(file, &fc->waitq, wait);

	spin_lock(&fuse_lock);
815 816 817 818
	if (!fc->connected)
		mask = POLLERR;
	else if (!list_empty(&fc->pending))
		mask |= POLLIN | POLLRDNORM;
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	spin_unlock(&fuse_lock);

	return mask;
}

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/*
 * Abort all requests on the given list (pending or processing)
 *
 * This function releases and reacquires fuse_lock
 */
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static void end_requests(struct fuse_conn *fc, struct list_head *head)
{
	while (!list_empty(head)) {
		struct fuse_req *req;
		req = list_entry(head->next, struct fuse_req, list);
		req->out.h.error = -ECONNABORTED;
		request_end(fc, req);
		spin_lock(&fuse_lock);
	}
}

840 841 842 843 844 845
/*
 * Abort requests under I/O
 *
 * The requests are set to interrupted and finished, and the request
 * waiter is woken up.  This will make request_wait_answer() wait
 * until the request is unlocked and then return.
846 847 848 849
 *
 * If the request is asynchronous, then the end function needs to be
 * called after waiting for the request to be unlocked (if it was
 * locked).
850 851 852 853
 */
static void end_io_requests(struct fuse_conn *fc)
{
	while (!list_empty(&fc->io)) {
854 855 856 857
		struct fuse_req *req =
			list_entry(fc->io.next, struct fuse_req, list);
		void (*end) (struct fuse_conn *, struct fuse_req *) = req->end;

858 859 860 861 862
		req->interrupted = 1;
		req->out.h.error = -ECONNABORTED;
		req->state = FUSE_REQ_FINISHED;
		list_del_init(&req->list);
		wake_up(&req->waitq);
863 864 865 866 867 868 869 870 871
		if (end) {
			req->end = NULL;
			/* The end function will consume this reference */
			__fuse_get_request(req);
			spin_unlock(&fuse_lock);
			wait_event(req->waitq, !req->locked);
			end(fc, req);
			spin_lock(&fuse_lock);
		}
872 873 874 875 876 877 878 879 880 881 882 883 884 885 886 887 888 889 890 891 892 893 894 895 896 897 898 899 900 901 902 903 904 905 906 907
	}
}

/*
 * Abort all requests.
 *
 * Emergency exit in case of a malicious or accidental deadlock, or
 * just a hung filesystem.
 *
 * The same effect is usually achievable through killing the
 * filesystem daemon and all users of the filesystem.  The exception
 * is the combination of an asynchronous request and the tricky
 * deadlock (see Documentation/filesystems/fuse.txt).
 *
 * During the aborting, progression of requests from the pending and
 * processing lists onto the io list, and progression of new requests
 * onto the pending list is prevented by req->connected being false.
 *
 * Progression of requests under I/O to the processing list is
 * prevented by the req->interrupted flag being true for these
 * requests.  For this reason requests on the io list must be aborted
 * first.
 */
void fuse_abort_conn(struct fuse_conn *fc)
{
	spin_lock(&fuse_lock);
	if (fc->connected) {
		fc->connected = 0;
		end_io_requests(fc);
		end_requests(fc, &fc->pending);
		end_requests(fc, &fc->processing);
		wake_up_all(&fc->waitq);
	}
	spin_unlock(&fuse_lock);
}

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static int fuse_dev_release(struct inode *inode, struct file *file)
{
	struct fuse_conn *fc;

	spin_lock(&fuse_lock);
	fc = file->private_data;
	if (fc) {
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		fc->connected = 0;
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		end_requests(fc, &fc->pending);
		end_requests(fc, &fc->processing);
	}
	spin_unlock(&fuse_lock);
920 921 922
	if (fc)
		kobject_put(&fc->kobj);

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	return 0;
}

926
const struct file_operations fuse_dev_operations = {
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	.owner		= THIS_MODULE,
	.llseek		= no_llseek,
	.read		= fuse_dev_read,
	.readv		= fuse_dev_readv,
	.write		= fuse_dev_write,
	.writev		= fuse_dev_writev,
	.poll		= fuse_dev_poll,
	.release	= fuse_dev_release,
};

static struct miscdevice fuse_miscdevice = {
	.minor = FUSE_MINOR,
	.name  = "fuse",
	.fops = &fuse_dev_operations,
};

int __init fuse_dev_init(void)
{
	int err = -ENOMEM;
	fuse_req_cachep = kmem_cache_create("fuse_request",
					    sizeof(struct fuse_req),
					    0, 0, NULL, NULL);
	if (!fuse_req_cachep)
		goto out;

	err = misc_register(&fuse_miscdevice);
	if (err)
		goto out_cache_clean;

	return 0;

 out_cache_clean:
	kmem_cache_destroy(fuse_req_cachep);
 out:
	return err;
}

void fuse_dev_cleanup(void)
{
	misc_deregister(&fuse_miscdevice);
	kmem_cache_destroy(fuse_req_cachep);
}