Initial import

1 files changed, 2273 insertions, 0 deletions

diff --git a/fs/fuse/dev.c b/fs/fuse/dev.c
new file mode 100644
index 000000000..c8b68ab2e
--- /dev/null
+++ b/fs/fuse/dev.c
@@ -0,0 +1,2273 @@
+/*
+  FUSE: Filesystem in Userspace
+  Copyright (C) 2001-2008  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>
+#include <linux/pipe_fs_i.h>
+#include <linux/swap.h>
+#include <linux/splice.h>
+
+MODULE_ALIAS_MISCDEV(FUSE_MINOR);
+MODULE_ALIAS("devname:fuse");
+
+static struct kmem_cache *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, struct page **pages,
+			      struct fuse_page_desc *page_descs,
+			      unsigned npages)
+{
+	memset(req, 0, sizeof(*req));
+	memset(pages, 0, sizeof(*pages) * npages);
+	memset(page_descs, 0, sizeof(*page_descs) * npages);
+	INIT_LIST_HEAD(&req->list);
+	INIT_LIST_HEAD(&req->intr_entry);
+	init_waitqueue_head(&req->waitq);
+	atomic_set(&req->count, 1);
+	req->pages = pages;
+	req->page_descs = page_descs;
+	req->max_pages = npages;
+}
+
+static struct fuse_req *__fuse_request_alloc(unsigned npages, gfp_t flags)
+{
+	struct fuse_req *req = kmem_cache_alloc(fuse_req_cachep, flags);
+	if (req) {
+		struct page **pages;
+		struct fuse_page_desc *page_descs;
+
+		if (npages <= FUSE_REQ_INLINE_PAGES) {
+			pages = req->inline_pages;
+			page_descs = req->inline_page_descs;
+		} else {
+			pages = kmalloc(sizeof(struct page *) * npages, flags);
+			page_descs = kmalloc(sizeof(struct fuse_page_desc) *
+					     npages, flags);
+		}
+
+		if (!pages || !page_descs) {
+			kfree(pages);
+			kfree(page_descs);
+			kmem_cache_free(fuse_req_cachep, req);
+			return NULL;
+		}
+
+		fuse_request_init(req, pages, page_descs, npages);
+	}
+	return req;
+}
+
+struct fuse_req *fuse_request_alloc(unsigned npages)
+{
+	return __fuse_request_alloc(npages, GFP_KERNEL);
+}
+EXPORT_SYMBOL_GPL(fuse_request_alloc);
+
+struct fuse_req *fuse_request_alloc_nofs(unsigned npages)
+{
+	return __fuse_request_alloc(npages, GFP_NOFS);
+}
+
+void fuse_request_free(struct fuse_req *req)
+{
+	if (req->pages != req->inline_pages) {
+		kfree(req->pages);
+		kfree(req->page_descs);
+	}
+	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);
+}
+
+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 void fuse_req_init_context(struct fuse_req *req)
+{
+	req->in.h.uid = from_kuid_munged(&init_user_ns, current_fsuid());
+	req->in.h.gid = from_kgid_munged(&init_user_ns, current_fsgid());
+	req->in.h.pid = current->pid;
+}
+
+void fuse_set_initialized(struct fuse_conn *fc)
+{
+	/* Make sure stores before this are seen on another CPU */
+	smp_wmb();
+	fc->initialized = 1;
+}
+
+static bool fuse_block_alloc(struct fuse_conn *fc, bool for_background)
+{
+	return !fc->initialized || (for_background && fc->blocked);
+}
+
+static struct fuse_req *__fuse_get_req(struct fuse_conn *fc, unsigned npages,
+				       bool for_background)
+{
+	struct fuse_req *req;
+	int err;
+	atomic_inc(&fc->num_waiting);
+
+	if (fuse_block_alloc(fc, for_background)) {
+		sigset_t oldset;
+		int intr;
+
+		block_sigs(&oldset);
+		intr = wait_event_interruptible_exclusive(fc->blocked_waitq,
+				!fuse_block_alloc(fc, for_background));
+		restore_sigs(&oldset);
+		err = -EINTR;
+		if (intr)
+			goto out;
+	}
+	/* Matches smp_wmb() in fuse_set_initialized() */
+	smp_rmb();
+
+	err = -ENOTCONN;
+	if (!fc->connected)
+		goto out;
+
+	req = fuse_request_alloc(npages);
+	err = -ENOMEM;
+	if (!req) {
+		if (for_background)
+			wake_up(&fc->blocked_waitq);
+		goto out;
+	}
+
+	fuse_req_init_context(req);
+	req->waiting = 1;
+	req->background = for_background;
+	return req;
+
+ out:
+	atomic_dec(&fc->num_waiting);
+	return ERR_PTR(err);
+}
+
+struct fuse_req *fuse_get_req(struct fuse_conn *fc, unsigned npages)
+{
+	return __fuse_get_req(fc, npages, false);
+}
+EXPORT_SYMBOL_GPL(fuse_get_req);
+
+struct fuse_req *fuse_get_req_for_background(struct fuse_conn *fc,
+					     unsigned npages)
+{
+	return __fuse_get_req(fc, npages, true);
+}
+EXPORT_SYMBOL_GPL(fuse_get_req_for_background);
+
+/*
+ * Return request in fuse_file->reserved_req.  However that may
+ * currently be in use.  If that is the case, wait for it to become
+ * available.
+ */
+static struct fuse_req *get_reserved_req(struct fuse_conn *fc,
+					 struct file *file)
+{
+	struct fuse_req *req = NULL;
+	struct fuse_file *ff = file->private_data;
+
+	do {
+		wait_event(fc->reserved_req_waitq, ff->reserved_req);
+		spin_lock(&fc->lock);
+		if (ff->reserved_req) {
+			req = ff->reserved_req;
+			ff->reserved_req = NULL;
+			req->stolen_file = get_file(file);
+		}
+		spin_unlock(&fc->lock);
+	} while (!req);
+
+	return req;
+}
+
+/*
+ * Put stolen request back into fuse_file->reserved_req
+ */
+static void put_reserved_req(struct fuse_conn *fc, struct fuse_req *req)
+{
+	struct file *file = req->stolen_file;
+	struct fuse_file *ff = file->private_data;
+
+	spin_lock(&fc->lock);
+	fuse_request_init(req, req->pages, req->page_descs, req->max_pages);
+	BUG_ON(ff->reserved_req);
+	ff->reserved_req = req;
+	wake_up_all(&fc->reserved_req_waitq);
+	spin_unlock(&fc->lock);
+	fput(file);
+}
+
+/*
+ * Gets a requests for a file operation, always succeeds
+ *
+ * This is used for sending the FLUSH request, which must get to
+ * userspace, due to POSIX locks which may need to be unlocked.
+ *
+ * If allocation fails due to OOM, use the reserved request in
+ * fuse_file.
+ *
+ * This is very unlikely to deadlock accidentally, since the
+ * filesystem should not have it's own file open.  If deadlock is
+ * intentional, it can still be broken by "aborting" the filesystem.
+ */
+struct fuse_req *fuse_get_req_nofail_nopages(struct fuse_conn *fc,
+					     struct file *file)
+{
+	struct fuse_req *req;
+
+	atomic_inc(&fc->num_waiting);
+	wait_event(fc->blocked_waitq, fc->initialized);
+	/* Matches smp_wmb() in fuse_set_initialized() */
+	smp_rmb();
+	req = fuse_request_alloc(0);
+	if (!req)
+		req = get_reserved_req(fc, file);
+
+	fuse_req_init_context(req);
+	req->waiting = 1;
+	req->background = 0;
+	return req;
+}
+
+void fuse_put_request(struct fuse_conn *fc, struct fuse_req *req)
+{
+	if (atomic_dec_and_test(&req->count)) {
+		if (unlikely(req->background)) {
+			/*
+			 * We get here in the unlikely case that a background
+			 * request was allocated but not sent
+			 */
+			spin_lock(&fc->lock);
+			if (!fc->blocked)
+				wake_up(&fc->blocked_waitq);
+			spin_unlock(&fc->lock);
+		}
+
+		if (req->waiting)
+			atomic_dec(&fc->num_waiting);
+
+		if (req->stolen_file)
+			put_reserved_req(fc, req);
+		else
+			fuse_request_free(req);
+	}
+}
+EXPORT_SYMBOL_GPL(fuse_put_request);
+
+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 u64 fuse_get_unique(struct fuse_conn *fc)
+{
+	fc->reqctr++;
+	/* zero is special */
+	if (fc->reqctr == 0)
+		fc->reqctr = 1;
+
+	return fc->reqctr;
+}
+
+static void queue_request(struct fuse_conn *fc, struct fuse_req *req)
+{
+	req->in.h.len = sizeof(struct fuse_in_header) +
+		len_args(req->in.numargs, (struct fuse_arg *) req->in.args);
+	list_add_tail(&req->list, &fc->pending);
+	req->state = FUSE_REQ_PENDING;
+	if (!req->waiting) {
+		req->waiting = 1;
+		atomic_inc(&fc->num_waiting);
+	}
+	wake_up(&fc->waitq);
+	kill_fasync(&fc->fasync, SIGIO, POLL_IN);
+}
+
+void fuse_queue_forget(struct fuse_conn *fc, struct fuse_forget_link *forget,
+		       u64 nodeid, u64 nlookup)
+{
+	forget->forget_one.nodeid = nodeid;
+	forget->forget_one.nlookup = nlookup;
+
+	spin_lock(&fc->lock);
+	if (fc->connected) {
+		fc->forget_list_tail->next = forget;
+		fc->forget_list_tail = forget;
+		wake_up(&fc->waitq);
+		kill_fasync(&fc->fasync, SIGIO, POLL_IN);
+	} else {
+		kfree(forget);
+	}
+	spin_unlock(&fc->lock);
+}
+
+static void flush_bg_queue(struct fuse_conn *fc)
+{
+	while (fc->active_background < fc->max_background &&
+	       !list_empty(&fc->bg_queue)) {
+		struct fuse_req *req;
+
+		req = list_entry(fc->bg_queue.next, struct fuse_req, list);
+		list_del(&req->list);
+		fc->active_background++;
+		req->in.h.unique = fuse_get_unique(fc);
+		queue_request(fc, req);
+	}
+}
+
+/*
+ * This function is called when a request is finished.  Either a reply
+ * has arrived or it was aborted (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)
+__releases(fc->lock)
+{
+	void (*end) (struct fuse_conn *, struct fuse_req *) = req->end;
+	req->end = NULL;
+	list_del(&req->list);
+	list_del(&req->intr_entry);
+	req->state = FUSE_REQ_FINISHED;
+	if (req->background) {
+		req->background = 0;
+
+		if (fc->num_background == fc->max_background)
+			fc->blocked = 0;
+
+		/* Wake up next waiter, if any */
+		if (!fc->blocked && waitqueue_active(&fc->blocked_waitq))
+			wake_up(&fc->blocked_waitq);
+
+		if (fc->num_background == fc->congestion_threshold &&
+		    fc->connected && fc->bdi_initialized) {
+			clear_bdi_congested(&fc->bdi, BLK_RW_SYNC);
+			clear_bdi_congested(&fc->bdi, BLK_RW_ASYNC);
+		}
+		fc->num_background--;
+		fc->active_background--;
+		flush_bg_queue(fc);
+	}
+	spin_unlock(&fc->lock);
+	wake_up(&req->waitq);
+	if (end)
+		end(fc, req);
+	fuse_put_request(fc, req);
+}
+
+static void wait_answer_interruptible(struct fuse_conn *fc,
+				      struct fuse_req *req)
+__releases(fc->lock)
+__acquires(fc->lock)
+{
+	if (signal_pending(current))
+		return;
+
+	spin_unlock(&fc->lock);
+	wait_event_interruptible(req->waitq, req->state == FUSE_REQ_FINISHED);
+	spin_lock(&fc->lock);
+}
+
+static void queue_interrupt(struct fuse_conn *fc, struct fuse_req *req)
+{
+	list_add_tail(&req->intr_entry, &fc->interrupts);
+	wake_up(&fc->waitq);
+	kill_fasync(&fc->fasync, SIGIO, POLL_IN);
+}
+
+static void request_wait_answer(struct fuse_conn *fc, struct fuse_req *req)
+__releases(fc->lock)
+__acquires(fc->lock)
+{
+	if (!fc->no_interrupt) {
+		/* Any signal may interrupt this */
+		wait_answer_interruptible(fc, req);
+
+		if (req->aborted)
+			goto aborted;
+		if (req->state == FUSE_REQ_FINISHED)
+			return;
+
+		req->interrupted = 1;
+		if (req->state == FUSE_REQ_SENT)
+			queue_interrupt(fc, req);
+	}
+
+	if (!req->force) {
+		sigset_t oldset;
+
+		/* Only fatal signals may interrupt this */
+		block_sigs(&oldset);
+		wait_answer_interruptible(fc, req);
+		restore_sigs(&oldset);
+
+		if (req->aborted)
+			goto aborted;
+		if (req->state == FUSE_REQ_FINISHED)
+			return;
+
+		/* Request is not yet in userspace, bail out */
+		if (req->state == FUSE_REQ_PENDING) {
+			list_del(&req->list);
+			__fuse_put_request(req);
+			req->out.h.error = -EINTR;
+			return;
+		}
+	}
+
+	/*
+	 * Either request is already in userspace, or it was forced.
+	 * Wait it out.
+	 */
+	spin_unlock(&fc->lock);
+	wait_event(req->waitq, req->state == FUSE_REQ_FINISHED);
+	spin_lock(&fc->lock);
+
+	if (!req->aborted)
+		return;
+
+ aborted:
+	BUG_ON(req->state != FUSE_REQ_FINISHED);
+	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(&fc->lock);
+		wait_event(req->waitq, !req->locked);
+		spin_lock(&fc->lock);
+	}
+}
+
+static void __fuse_request_send(struct fuse_conn *fc, struct fuse_req *req)
+{
+	BUG_ON(req->background);
+	spin_lock(&fc->lock);
+	if (!fc->connected)
+		req->out.h.error = -ENOTCONN;
+	else if (fc->conn_error)
+		req->out.h.error = -ECONNREFUSED;
+	else {
+		req->in.h.unique = fuse_get_unique(fc);
+		queue_request(fc, req);
+		/* acquire extra reference, since request is still needed
+		   after request_end() */
+		__fuse_get_request(req);
+
+		request_wait_answer(fc, req);
+	}
+	spin_unlock(&fc->lock);
+}
+
+void fuse_request_send(struct fuse_conn *fc, struct fuse_req *req)
+{
+	req->isreply = 1;
+	__fuse_request_send(fc, req);
+}
+EXPORT_SYMBOL_GPL(fuse_request_send);
+
+static void fuse_adjust_compat(struct fuse_conn *fc, struct fuse_args *args)
+{
+	if (fc->minor < 4 && args->in.h.opcode == FUSE_STATFS)
+		args->out.args[0].size = FUSE_COMPAT_STATFS_SIZE;
+
+	if (fc->minor < 9) {
+		switch (args->in.h.opcode) {
+		case FUSE_LOOKUP:
+		case FUSE_CREATE:
+		case FUSE_MKNOD:
+		case FUSE_MKDIR:
+		case FUSE_SYMLINK:
+		case FUSE_LINK:
+			args->out.args[0].size = FUSE_COMPAT_ENTRY_OUT_SIZE;
+			break;
+		case FUSE_GETATTR:
+		case FUSE_SETATTR:
+			args->out.args[0].size = FUSE_COMPAT_ATTR_OUT_SIZE;
+			break;
+		}
+	}
+	if (fc->minor < 12) {
+		switch (args->in.h.opcode) {
+		case FUSE_CREATE:
+			args->in.args[0].size = sizeof(struct fuse_open_in);
+			break;
+		case FUSE_MKNOD:
+			args->in.args[0].size = FUSE_COMPAT_MKNOD_IN_SIZE;
+			break;
+		}
+	}
+}
+
+ssize_t fuse_simple_request(struct fuse_conn *fc, struct fuse_args *args)
+{
+	struct fuse_req *req;
+	ssize_t ret;
+
+	req = fuse_get_req(fc, 0);
+	if (IS_ERR(req))
+		return PTR_ERR(req);
+
+	/* Needs to be done after fuse_get_req() so that fc->minor is valid */
+	fuse_adjust_compat(fc, args);
+
+	req->in.h.opcode = args->in.h.opcode;
+	req->in.h.nodeid = args->in.h.nodeid;
+	req->in.numargs = args->in.numargs;
+	memcpy(req->in.args, args->in.args,
+	       args->in.numargs * sizeof(struct fuse_in_arg));
+	req->out.argvar = args->out.argvar;
+	req->out.numargs = args->out.numargs;
+	memcpy(req->out.args, args->out.args,
+	       args->out.numargs * sizeof(struct fuse_arg));
+	fuse_request_send(fc, req);
+	ret = req->out.h.error;
+	if (!ret && args->out.argvar) {
+		BUG_ON(args->out.numargs != 1);
+		ret = req->out.args[0].size;
+	}
+	fuse_put_request(fc, req);
+
+	return ret;
+}
+
+static void fuse_request_send_nowait_locked(struct fuse_conn *fc,
+					    struct fuse_req *req)
+{
+	BUG_ON(!req->background);
+	fc->num_background++;
+	if (fc->num_background == fc->max_background)
+		fc->blocked = 1;
+	if (fc->num_background == fc->congestion_threshold &&
+	    fc->bdi_initialized) {
+		set_bdi_congested(&fc->bdi, BLK_RW_SYNC);
+		set_bdi_congested(&fc->bdi, BLK_RW_ASYNC);
+	}
+	list_add_tail(&req->list, &fc->bg_queue);
+	flush_bg_queue(fc);
+}
+
+static void fuse_request_send_nowait(struct fuse_conn *fc, struct fuse_req *req)
+{
+	spin_lock(&fc->lock);
+	if (fc->connected) {
+		fuse_request_send_nowait_locked(fc, req);
+		spin_unlock(&fc->lock);
+	} else {
+		req->out.h.error = -ENOTCONN;
+		request_end(fc, req);
+	}
+}
+
+void fuse_request_send_background(struct fuse_conn *fc, struct fuse_req *req)
+{
+	req->isreply = 1;
+	fuse_request_send_nowait(fc, req);
+}
+EXPORT_SYMBOL_GPL(fuse_request_send_background);
+
+static int fuse_request_send_notify_reply(struct fuse_conn *fc,
+					  struct fuse_req *req, u64 unique)
+{
+	int err = -ENODEV;
+
+	req->isreply = 0;
+	req->in.h.unique = unique;
+	spin_lock(&fc->lock);
+	if (fc->connected) {
+		queue_request(fc, req);
+		err = 0;
+	}
+	spin_unlock(&fc->lock);
+
+	return err;
+}
+
+/*
+ * Called under fc->lock
+ *
+ * fc->connected must have been checked previously
+ */
+void fuse_request_send_background_locked(struct fuse_conn *fc,
+					 struct fuse_req *req)
+{
+	req->isreply = 1;
+	fuse_request_send_nowait_locked(fc, req);
+}
+
+void fuse_force_forget(struct file *file, u64 nodeid)
+{
+	struct inode *inode = file_inode(file);
+	struct fuse_conn *fc = get_fuse_conn(inode);
+	struct fuse_req *req;
+	struct fuse_forget_in inarg;
+
+	memset(&inarg, 0, sizeof(inarg));
+	inarg.nlookup = 1;
+	req = fuse_get_req_nofail_nopages(fc, file);
+	req->in.h.opcode = FUSE_FORGET;
+	req->in.h.nodeid = nodeid;
+	req->in.numargs = 1;
+	req->in.args[0].size = sizeof(inarg);
+	req->in.args[0].value = &inarg;
+	req->isreply = 0;
+	__fuse_request_send(fc, req);
+	/* ignore errors */
+	fuse_put_request(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
+ * aborted bail out.
+ */
+static int lock_request(struct fuse_conn *fc, struct fuse_req *req)
+{
+	int err = 0;
+	if (req) {
+		spin_lock(&fc->lock);
+		if (req->aborted)
+			err = -ENOENT;
+		else
+			req->locked = 1;
+		spin_unlock(&fc->lock);
+	}
+	return err;
+}
+
+/*
+ * Unlock request.  If it was aborted during being locked, the
+ * requester thread is currently waiting for it to be unlocked, so
+ * wake it up.
+ */
+static void unlock_request(struct fuse_conn *fc, struct fuse_req *req)
+{
+	if (req) {
+		spin_lock(&fc->lock);
+		req->locked = 0;
+		if (req->aborted)
+			wake_up(&req->waitq);
+		spin_unlock(&fc->lock);
+	}
+}
+
+struct fuse_copy_state {
+	struct fuse_conn *fc;
+	int write;
+	struct fuse_req *req;
+	struct iov_iter *iter;
+	struct pipe_buffer *pipebufs;
+	struct pipe_buffer *currbuf;
+	struct pipe_inode_info *pipe;
+	unsigned long nr_segs;
+	struct page *pg;
+	unsigned len;
+	unsigned offset;
+	unsigned move_pages:1;
+};
+
+static void fuse_copy_init(struct fuse_copy_state *cs,
+			   struct fuse_conn *fc,
+			   int write,
+			   struct iov_iter *iter)
+{
+	memset(cs, 0, sizeof(*cs));
+	cs->fc = fc;
+	cs->write = write;
+	cs->iter = iter;
+}
+
+/* Unmap and put previous page of userspace buffer */
+static void fuse_copy_finish(struct fuse_copy_state *cs)
+{
+	if (cs->currbuf) {
+		struct pipe_buffer *buf = cs->currbuf;
+
+		if (cs->write)
+			buf->len = PAGE_SIZE - cs->len;
+		cs->currbuf = NULL;
+	} else if (cs->pg) {
+		if (cs->write) {
+			flush_dcache_page(cs->pg);
+			set_page_dirty_lock(cs->pg);
+		}
+		put_page(cs->pg);
+	}
+	cs->pg = 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)
+{
+	struct page *page;
+	int err;
+
+	unlock_request(cs->fc, cs->req);
+	fuse_copy_finish(cs);
+	if (cs->pipebufs) {
+		struct pipe_buffer *buf = cs->pipebufs;
+
+		if (!cs->write) {
+			err = buf->ops->confirm(cs->pipe, buf);
+			if (err)
+				return err;
+
+			BUG_ON(!cs->nr_segs);
+			cs->currbuf = buf;
+			cs->pg = buf->page;
+			cs->offset = buf->offset;
+			cs->len = buf->len;
+			cs->pipebufs++;
+			cs->nr_segs--;
+		} else {
+			if (cs->nr_segs == cs->pipe->buffers)
+				return -EIO;
+
+			page = alloc_page(GFP_HIGHUSER);
+			if (!page)
+				return -ENOMEM;
+
+			buf->page = page;
+			buf->offset = 0;
+			buf->len = 0;
+
+			cs->currbuf = buf;
+			cs->pg = page;
+			cs->offset = 0;
+			cs->len = PAGE_SIZE;
+			cs->pipebufs++;
+			cs->nr_segs++;
+		}
+	} else {
+		size_t off;
+		err = iov_iter_get_pages(cs->iter, &page, PAGE_SIZE, 1, &off);
+		if (err < 0)
+			return err;
+		BUG_ON(!err);
+		cs->len = err;
+		cs->offset = off;
+		cs->pg = page;
+		cs->offset = off;
+		iov_iter_advance(cs->iter, err);
+	}
+
+	return lock_request(cs->fc, cs->req);
+}
+
+/* Do as much copy to/from userspace buffer as we can */
+static int fuse_copy_do(struct fuse_copy_state *cs, void **val, unsigned *size)
+{
+	unsigned ncpy = min(*size, cs->len);
+	if (val) {
+		void *pgaddr = kmap_atomic(cs->pg);
+		void *buf = pgaddr + cs->offset;
+
+		if (cs->write)
+			memcpy(buf, *val, ncpy);
+		else
+			memcpy(*val, buf, ncpy);
+
+		kunmap_atomic(pgaddr);
+		*val += ncpy;
+	}
+	*size -= ncpy;
+	cs->len -= ncpy;
+	cs->offset += ncpy;
+	return ncpy;
+}
+
+static int fuse_check_page(struct page *page)
+{
+	if (page_mapcount(page) ||
+	    page->mapping != NULL ||
+	    page_count(page) != 1 ||
+	    (page->flags & PAGE_FLAGS_CHECK_AT_PREP &
+	     ~(1 << PG_locked |
+	       1 << PG_referenced |
+	       1 << PG_uptodate |
+	       1 << PG_lru |
+	       1 << PG_active |
+	       1 << PG_reclaim))) {
+		printk(KERN_WARNING "fuse: trying to steal weird page\n");
+		printk(KERN_WARNING "  page=%p index=%li flags=%08lx, count=%i, mapcount=%i, mapping=%p\n", page, page->index, page->flags, page_count(page), page_mapcount(page), page->mapping);
+		return 1;
+	}
+	return 0;
+}
+
+static int fuse_try_move_page(struct fuse_copy_state *cs, struct page **pagep)
+{
+	int err;
+	struct page *oldpage = *pagep;
+	struct page *newpage;
+	struct pipe_buffer *buf = cs->pipebufs;
+
+	unlock_request(cs->fc, cs->req);
+	fuse_copy_finish(cs);
+
+	err = buf->ops->confirm(cs->pipe, buf);
+	if (err)
+		return err;
+
+	BUG_ON(!cs->nr_segs);
+	cs->currbuf = buf;
+	cs->len = buf->len;
+	cs->pipebufs++;
+	cs->nr_segs--;
+
+	if (cs->len != PAGE_SIZE)
+		goto out_fallback;
+
+	if (buf->ops->steal(cs->pipe, buf) != 0)
+		goto out_fallback;
+
+	newpage = buf->page;
+
+	if (!PageUptodate(newpage))
+		SetPageUptodate(newpage);
+
+	ClearPageMappedToDisk(newpage);
+
+	if (fuse_check_page(newpage) != 0)
+		goto out_fallback_unlock;
+
+	/*
+	 * This is a new and locked page, it shouldn't be mapped or
+	 * have any special flags on it
+	 */
+	if (WARN_ON(page_mapped(oldpage)))
+		goto out_fallback_unlock;
+	if (WARN_ON(page_has_private(oldpage)))
+		goto out_fallback_unlock;
+	if (WARN_ON(PageDirty(oldpage) || PageWriteback(oldpage)))
+		goto out_fallback_unlock;
+	if (WARN_ON(PageMlocked(oldpage)))
+		goto out_fallback_unlock;
+
+	err = replace_page_cache_page(oldpage, newpage, GFP_KERNEL);
+	if (err) {
+		unlock_page(newpage);
+		return err;
+	}
+
+	page_cache_get(newpage);
+
+	if (!(buf->flags & PIPE_BUF_FLAG_LRU))
+		lru_cache_add_file(newpage);
+
+	err = 0;
+	spin_lock(&cs->fc->lock);
+	if (cs->req->aborted)
+		err = -ENOENT;
+	else
+		*pagep = newpage;
+	spin_unlock(&cs->fc->lock);
+
+	if (err) {
+		unlock_page(newpage);
+		page_cache_release(newpage);
+		return err;
+	}
+
+	unlock_page(oldpage);
+	page_cache_release(oldpage);
+	cs->len = 0;
+
+	return 0;
+
+out_fallback_unlock:
+	unlock_page(newpage);
+out_fallback:
+	cs->pg = buf->page;
+	cs->offset = buf->offset;
+
+	err = lock_request(cs->fc, cs->req);
+	if (err)
+		return err;
+
+	return 1;
+}
+
+static int fuse_ref_page(struct fuse_copy_state *cs, struct page *page,
+			 unsigned offset, unsigned count)
+{
+	struct pipe_buffer *buf;
+
+	if (cs->nr_segs == cs->pipe->buffers)
+		return -EIO;
+
+	unlock_request(cs->fc, cs->req);
+	fuse_copy_finish(cs);
+
+	buf = cs->pipebufs;
+	page_cache_get(page);
+	buf->page = page;
+	buf->offset = offset;
+	buf->len = count;
+
+	cs->pipebufs++;
+	cs->nr_segs++;
+	cs->len = 0;
+
+	return 0;
+}
+
+/*
+ * Copy a page in the request to/from the userspace buffer.  Must be
+ * done atomically
+ */
+static int fuse_copy_page(struct fuse_copy_state *cs, struct page **pagep,
+			  unsigned offset, unsigned count, int zeroing)
+{
+	int err;
+	struct page *page = *pagep;
+
+	if (page && zeroing && count < PAGE_SIZE)
+		clear_highpage(page);
+
+	while (count) {
+		if (cs->write && cs->pipebufs && page) {
+			return fuse_ref_page(cs, page, offset, count);
+		} else if (!cs->len) {
+			if (cs->move_pages && page &&
+			    offset == 0 && count == PAGE_SIZE) {
+				err = fuse_try_move_page(cs, pagep);
+				if (err <= 0)
+					return err;
+			} else {
+				err = fuse_copy_fill(cs);
+				if (err)
+					return err;
+			}
+		}
+		if (page) {
+			void *mapaddr = kmap_atomic(page);
+			void *buf = mapaddr + offset;
+			offset += fuse_copy_do(cs, &buf, &count);
+			kunmap_atomic(mapaddr);
+		} 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;
+
+	for (i = 0; i < req->num_pages && (nbytes || zeroing); i++) {
+		int err;
+		unsigned offset = req->page_descs[i].offset;
+		unsigned count = min(nbytes, req->page_descs[i].length);
+
+		err = fuse_copy_page(cs, &req->pages[i], offset, count,
+				     zeroing);
+		if (err)
+			return err;
+
+		nbytes -= count;
+	}
+	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) {
+		if (!cs->len) {
+			int err = fuse_copy_fill(cs);
+			if (err)
+				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;
+}
+
+static int forget_pending(struct fuse_conn *fc)
+{
+	return fc->forget_list_head.next != NULL;
+}
+
+static int request_pending(struct fuse_conn *fc)
+{
+	return !list_empty(&fc->pending) || !list_empty(&fc->interrupts) ||
+		forget_pending(fc);
+}
+
+/* Wait until a request is available on the pending list */
+static void request_wait(struct fuse_conn *fc)
+__releases(fc->lock)
+__acquires(fc->lock)
+{
+	DECLARE_WAITQUEUE(wait, current);
+
+	add_wait_queue_exclusive(&fc->waitq, &wait);
+	while (fc->connected && !request_pending(fc)) {
+		set_current_state(TASK_INTERRUPTIBLE);
+		if (signal_pending(current))
+			break;
+
+		spin_unlock(&fc->lock);
+		schedule();
+		spin_lock(&fc->lock);
+	}
+	set_current_state(TASK_RUNNING);
+	remove_wait_queue(&fc->waitq, &wait);
+}
+
+/*
+ * Transfer an interrupt request to userspace
+ *
+ * Unlike other requests this is assembled on demand, without a need
+ * to allocate a separate fuse_req structure.
+ *
+ * Called with fc->lock held, releases it
+ */
+static int fuse_read_interrupt(struct fuse_conn *fc, struct fuse_copy_state *cs,
+			       size_t nbytes, struct fuse_req *req)
+__releases(fc->lock)
+{
+	struct fuse_in_header ih;
+	struct fuse_interrupt_in arg;
+	unsigned reqsize = sizeof(ih) + sizeof(arg);
+	int err;
+
+	list_del_init(&req->intr_entry);
+	req->intr_unique = fuse_get_unique(fc);
+	memset(&ih, 0, sizeof(ih));
+	memset(&arg, 0, sizeof(arg));
+	ih.len = reqsize;
+	ih.opcode = FUSE_INTERRUPT;
+	ih.unique = req->intr_unique;
+	arg.unique = req->in.h.unique;
+
+	spin_unlock(&fc->lock);
+	if (nbytes < reqsize)
+		return -EINVAL;
+
+	err = fuse_copy_one(cs, &ih, sizeof(ih));
+	if (!err)
+		err = fuse_copy_one(cs, &arg, sizeof(arg));
+	fuse_copy_finish(cs);
+
+	return err ? err : reqsize;
+}
+
+static struct fuse_forget_link *dequeue_forget(struct fuse_conn *fc,
+					       unsigned max,
+					       unsigned *countp)
+{
+	struct fuse_forget_link *head = fc->forget_list_head.next;
+	struct fuse_forget_link **newhead = &head;
+	unsigned count;
+
+	for (count = 0; *newhead != NULL && count < max; count++)
+		newhead = &(*newhead)->next;
+
+	fc->forget_list_head.next = *newhead;
+	*newhead = NULL;
+	if (fc->forget_list_head.next == NULL)
+		fc->forget_list_tail = &fc->forget_list_head;
+
+	if (countp != NULL)
+		*countp = count;
+
+	return head;
+}
+
+static int fuse_read_single_forget(struct fuse_conn *fc,
+				   struct fuse_copy_state *cs,
+				   size_t nbytes)
+__releases(fc->lock)
+{
+	int err;
+	struct fuse_forget_link *forget = dequeue_forget(fc, 1, NULL);
+	struct fuse_forget_in arg = {
+		.nlookup = forget->forget_one.nlookup,
+	};
+	struct fuse_in_header ih = {
+		.opcode = FUSE_FORGET,
+		.nodeid = forget->forget_one.nodeid,
+		.unique = fuse_get_unique(fc),
+		.len = sizeof(ih) + sizeof(arg),
+	};
+
+	spin_unlock(&fc->lock);
+	kfree(forget);
+	if (nbytes < ih.len)
+		return -EINVAL;
+
+	err = fuse_copy_one(cs, &ih, sizeof(ih));
+	if (!err)
+		err = fuse_copy_one(cs, &arg, sizeof(arg));
+	fuse_copy_finish(cs);
+
+	if (err)
+		return err;
+
+	return ih.len;
+}
+
+static int fuse_read_batch_forget(struct fuse_conn *fc,
+				   struct fuse_copy_state *cs, size_t nbytes)
+__releases(fc->lock)
+{
+	int err;
+	unsigned max_forgets;
+	unsigned count;
+	struct fuse_forget_link *head;
+	struct fuse_batch_forget_in arg = { .count = 0 };
+	struct fuse_in_header ih = {
+		.opcode = FUSE_BATCH_FORGET,
+		.unique = fuse_get_unique(fc),
+		.len = sizeof(ih) + sizeof(arg),
+	};
+
+	if (nbytes < ih.len) {
+		spin_unlock(&fc->lock);
+		return -EINVAL;
+	}
+
+	max_forgets = (nbytes - ih.len) / sizeof(struct fuse_forget_one);
+	head = dequeue_forget(fc, max_forgets, &count);
+	spin_unlock(&fc->lock);
+
+	arg.count = count;
+	ih.len += count * sizeof(struct fuse_forget_one);
+	err = fuse_copy_one(cs, &ih, sizeof(ih));
+	if (!err)
+		err = fuse_copy_one(cs, &arg, sizeof(arg));
+
+	while (head) {
+		struct fuse_forget_link *forget = head;
+
+		if (!err) {
+			err = fuse_copy_one(cs, &forget->forget_one,
+					    sizeof(forget->forget_one));
+		}
+		head = forget->next;
+		kfree(forget);
+	}
+
+	fuse_copy_finish(cs);
+
+	if (err)
+		return err;
+
+	return ih.len;
+}
+
+static int fuse_read_forget(struct fuse_conn *fc, struct fuse_copy_state *cs,
+			    size_t nbytes)
+__releases(fc->lock)
+{
+	if (fc->minor < 16 || fc->forget_list_head.next->next == NULL)
+		return fuse_read_single_forget(fc, cs, nbytes);
+	else
+		return fuse_read_batch_forget(fc, cs, nbytes);
+}
+
+/*
+ * 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 aborted 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_do_read(struct fuse_conn *fc, struct file *file,
+				struct fuse_copy_state *cs, size_t nbytes)
+{
+	int err;
+	struct fuse_req *req;
+	struct fuse_in *in;
+	unsigned reqsize;
+
+ restart:
+	spin_lock(&fc->lock);
+	err = -EAGAIN;
+	if ((file->f_flags & O_NONBLOCK) && fc->connected &&
+	    !request_pending(fc))
+		goto err_unlock;
+
+	request_wait(fc);
+	err = -ENODEV;
+	if (!fc->connected)
+		goto err_unlock;
+	err = -ERESTARTSYS;
+	if (!request_pending(fc))
+		goto err_unlock;
+
+	if (!list_empty(&fc->interrupts)) {
+		req = list_entry(fc->interrupts.next, struct fuse_req,
+				 intr_entry);
+		return fuse_read_interrupt(fc, cs, nbytes, req);
+	}
+
+	if (forget_pending(fc)) {
+		if (list_empty(&fc->pending) || fc->forget_batch-- > 0)
+			return fuse_read_forget(fc, cs, nbytes);
+
+		if (fc->forget_batch <= -8)
+			fc->forget_batch = 16;
+	}
+
+	req = list_entry(fc->pending.next, struct fuse_req, list);
+	req->state = FUSE_REQ_READING;
+	list_move(&req->list, &fc->io);
+
+	in = &req->in;
+	reqsize = in->h.len;
+	/* If request is too large, reply with an error and restart the read */
+	if (nbytes < 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;
+	}
+	spin_unlock(&fc->lock);
+	cs->req = req;
+	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);
+	fuse_copy_finish(cs);
+	spin_lock(&fc->lock);
+	req->locked = 0;
+	if (req->aborted) {
+		request_end(fc, req);
+		return -ENODEV;
+	}
+	if (err) {
+		req->out.h.error = -EIO;
+		request_end(fc, req);
+		return err;
+	}
+	if (!req->isreply)
+		request_end(fc, req);
+	else {
+		req->state = FUSE_REQ_SENT;
+		list_move_tail(&req->list, &fc->processing);
+		if (req->interrupted)
+			queue_interrupt(fc, req);
+		spin_unlock(&fc->lock);
+	}
+	return reqsize;
+
+ err_unlock:
+	spin_unlock(&fc->lock);
+	return err;
+}
+
+static int fuse_dev_open(struct inode *inode, struct file *file)
+{
+	/*
+	 * The fuse device's file's private_data is used to hold
+	 * the fuse_conn(ection) when it is mounted, and is used to
+	 * keep track of whether the file has been mounted already.
+	 */
+	file->private_data = NULL;
+	return 0;
+}
+
+static ssize_t fuse_dev_read(struct kiocb *iocb, struct iov_iter *to)
+{
+	struct fuse_copy_state cs;
+	struct file *file = iocb->ki_filp;
+	struct fuse_conn *fc = fuse_get_conn(file);
+	if (!fc)
+		return -EPERM;
+
+	if (!iter_is_iovec(to))
+		return -EINVAL;
+
+	fuse_copy_init(&cs, fc, 1, to);
+
+	return fuse_dev_do_read(fc, file, &cs, iov_iter_count(to));
+}
+
+static ssize_t fuse_dev_splice_read(struct file *in, loff_t *ppos,
+				    struct pipe_inode_info *pipe,
+				    size_t len, unsigned int flags)
+{
+	int ret;
+	int page_nr = 0;
+	int do_wakeup = 0;
+	struct pipe_buffer *bufs;
+	struct fuse_copy_state cs;
+	struct fuse_conn *fc = fuse_get_conn(in);
+	if (!fc)
+		return -EPERM;
+
+	bufs = kmalloc(pipe->buffers * sizeof(struct pipe_buffer), GFP_KERNEL);
+	if (!bufs)
+		return -ENOMEM;
+
+	fuse_copy_init(&cs, fc, 1, NULL);
+	cs.pipebufs = bufs;
+	cs.pipe = pipe;
+	ret = fuse_dev_do_read(fc, in, &cs, len);
+	if (ret < 0)
+		goto out;
+
+	ret = 0;
+	pipe_lock(pipe);
+
+	if (!pipe->readers) {
+		send_sig(SIGPIPE, current, 0);
+		if (!ret)
+			ret = -EPIPE;
+		goto out_unlock;
+	}
+
+	if (pipe->nrbufs + cs.nr_segs > pipe->buffers) {
+		ret = -EIO;
+		goto out_unlock;
+	}
+
+	while (page_nr < cs.nr_segs) {
+		int newbuf = (pipe->curbuf + pipe->nrbufs) & (pipe->buffers - 1);
+		struct pipe_buffer *buf = pipe->bufs + newbuf;
+
+		buf->page = bufs[page_nr].page;
+		buf->offset = bufs[page_nr].offset;
+		buf->len = bufs[page_nr].len;
+		/*
+		 * Need to be careful about this.  Having buf->ops in module
+		 * code can Oops if the buffer persists after module unload.
+		 */
+		buf->ops = &nosteal_pipe_buf_ops;
+
+		pipe->nrbufs++;
+		page_nr++;
+		ret += buf->len;
+
+		if (pipe->files)
+			do_wakeup = 1;
+	}
+
+out_unlock:
+	pipe_unlock(pipe);
+
+	if (do_wakeup) {
+		smp_mb();
+		if (waitqueue_active(&pipe->wait))
+			wake_up_interruptible(&pipe->wait);
+		kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN);
+	}
+
+out:
+	for (; page_nr < cs.nr_segs; page_nr++)
+		page_cache_release(bufs[page_nr].page);
+
+	kfree(bufs);
+	return ret;
+}
+
+static int fuse_notify_poll(struct fuse_conn *fc, unsigned int size,
+			    struct fuse_copy_state *cs)
+{
+	struct fuse_notify_poll_wakeup_out outarg;
+	int err = -EINVAL;
+
+	if (size != sizeof(outarg))
+		goto err;
+
+	err = fuse_copy_one(cs, &outarg, sizeof(outarg));
+	if (err)
+		goto err;
+
+	fuse_copy_finish(cs);
+	return fuse_notify_poll_wakeup(fc, &outarg);
+
+err:
+	fuse_copy_finish(cs);
+	return err;
+}
+
+static int fuse_notify_inval_inode(struct fuse_conn *fc, unsigned int size,
+				   struct fuse_copy_state *cs)
+{
+	struct fuse_notify_inval_inode_out outarg;
+	int err = -EINVAL;
+
+	if (size != sizeof(outarg))
+		goto err;
+
+	err = fuse_copy_one(cs, &outarg, sizeof(outarg));
+	if (err)
+		goto err;
+	fuse_copy_finish(cs);
+
+	down_read(&fc->killsb);
+	err = -ENOENT;
+	if (fc->sb) {
+		err = fuse_reverse_inval_inode(fc->sb, outarg.ino,
+					       outarg.off, outarg.len);
+	}
+	up_read(&fc->killsb);
+	return err;
+
+err:
+	fuse_copy_finish(cs);
+	return err;
+}
+
+static int fuse_notify_inval_entry(struct fuse_conn *fc, unsigned int size,
+				   struct fuse_copy_state *cs)
+{
+	struct fuse_notify_inval_entry_out outarg;
+	int err = -ENOMEM;
+	char *buf;
+	struct qstr name;
+
+	buf = kzalloc(FUSE_NAME_MAX + 1, GFP_KERNEL);
+	if (!buf)
+		goto err;
+
+	err = -EINVAL;
+	if (size < sizeof(outarg))
+		goto err;
+
+	err = fuse_copy_one(cs, &outarg, sizeof(outarg));
+	if (err)
+		goto err;
+
+	err = -ENAMETOOLONG;
+	if (outarg.namelen > FUSE_NAME_MAX)
+		goto err;
+
+	err = -EINVAL;
+	if (size != sizeof(outarg) + outarg.namelen + 1)
+		goto err;
+
+	name.name = buf;
+	name.len = outarg.namelen;
+	err = fuse_copy_one(cs, buf, outarg.namelen + 1);
+	if (err)
+		goto err;
+	fuse_copy_finish(cs);
+	buf[outarg.namelen] = 0;
+	name.hash = full_name_hash(name.name, name.len);
+
+	down_read(&fc->killsb);
+	err = -ENOENT;
+	if (fc->sb)
+		err = fuse_reverse_inval_entry(fc->sb, outarg.parent, 0, &name);
+	up_read(&fc->killsb);
+	kfree(buf);
+	return err;
+
+err:
+	kfree(buf);
+	fuse_copy_finish(cs);
+	return err;
+}
+
+static int fuse_notify_delete(struct fuse_conn *fc, unsigned int size,
+			      struct fuse_copy_state *cs)
+{
+	struct fuse_notify_delete_out outarg;
+	int err = -ENOMEM;
+	char *buf;
+	struct qstr name;
+
+	buf = kzalloc(FUSE_NAME_MAX + 1, GFP_KERNEL);
+	if (!buf)
+		goto err;
+
+	err = -EINVAL;
+	if (size < sizeof(outarg))
+		goto err;
+
+	err = fuse_copy_one(cs, &outarg, sizeof(outarg));
+	if (err)
+		goto err;
+
+	err = -ENAMETOOLONG;
+	if (outarg.namelen > FUSE_NAME_MAX)
+		goto err;
+
+	err = -EINVAL;
+	if (size != sizeof(outarg) + outarg.namelen + 1)
+		goto err;
+
+	name.name = buf;
+	name.len = outarg.namelen;
+	err = fuse_copy_one(cs, buf, outarg.namelen + 1);
+	if (err)
+		goto err;
+	fuse_copy_finish(cs);
+	buf[outarg.namelen] = 0;
+	name.hash = full_name_hash(name.name, name.len);
+
+	down_read(&fc->killsb);
+	err = -ENOENT;
+	if (fc->sb)
+		err = fuse_reverse_inval_entry(fc->sb, outarg.parent,
+					       outarg.child, &name);
+	up_read(&fc->killsb);
+	kfree(buf);
+	return err;
+
+err:
+	kfree(buf);
+	fuse_copy_finish(cs);
+	return err;
+}
+
+static int fuse_notify_store(struct fuse_conn *fc, unsigned int size,
+			     struct fuse_copy_state *cs)
+{
+	struct fuse_notify_store_out outarg;
+	struct inode *inode;
+	struct address_space *mapping;
+	u64 nodeid;
+	int err;
+	pgoff_t index;
+	unsigned int offset;
+	unsigned int num;
+	loff_t file_size;
+	loff_t end;
+
+	err = -EINVAL;
+	if (size < sizeof(outarg))
+		goto out_finish;
+
+	err = fuse_copy_one(cs, &outarg, sizeof(outarg));
+	if (err)
+		goto out_finish;
+
+	err = -EINVAL;
+	if (size - sizeof(outarg) != outarg.size)
+		goto out_finish;
+
+	nodeid = outarg.nodeid;
+
+	down_read(&fc->killsb);
+
+	err = -ENOENT;
+	if (!fc->sb)
+		goto out_up_killsb;
+
+	inode = ilookup5(fc->sb, nodeid, fuse_inode_eq, &nodeid);
+	if (!inode)
+		goto out_up_killsb;
+
+	mapping = inode->i_mapping;
+	index = outarg.offset >> PAGE_CACHE_SHIFT;
+	offset = outarg.offset & ~PAGE_CACHE_MASK;
+	file_size = i_size_read(inode);
+	end = outarg.offset + outarg.size;
+	if (end > file_size) {
+		file_size = end;
+		fuse_write_update_size(inode, file_size);
+	}
+
+	num = outarg.size;
+	while (num) {
+		struct page *page;
+		unsigned int this_num;
+
+		err = -ENOMEM;
+		page = find_or_create_page(mapping, index,
+					   mapping_gfp_mask(mapping));
+		if (!page)
+			goto out_iput;
+
+		this_num = min_t(unsigned, num, PAGE_CACHE_SIZE - offset);
+		err = fuse_copy_page(cs, &page, offset, this_num, 0);
+		if (!err && offset == 0 &&
+		    (this_num == PAGE_CACHE_SIZE || file_size == end))
+			SetPageUptodate(page);
+		unlock_page(page);
+		page_cache_release(page);
+
+		if (err)
+			goto out_iput;
+
+		num -= this_num;
+		offset = 0;
+		index++;
+	}
+
+	err = 0;
+
+out_iput:
+	iput(inode);
+out_up_killsb:
+	up_read(&fc->killsb);
+out_finish:
+	fuse_copy_finish(cs);
+	return err;
+}
+
+static void fuse_retrieve_end(struct fuse_conn *fc, struct fuse_req *req)
+{
+	release_pages(req->pages, req->num_pages, false);
+}
+
+static int fuse_retrieve(struct fuse_conn *fc, struct inode *inode,
+			 struct fuse_notify_retrieve_out *outarg)
+{
+	int err;
+	struct address_space *mapping = inode->i_mapping;
+	struct fuse_req *req;
+	pgoff_t index;
+	loff_t file_size;
+	unsigned int num;
+	unsigned int offset;
+	size_t total_len = 0;
+	int num_pages;
+
+	offset = outarg->offset & ~PAGE_CACHE_MASK;
+	file_size = i_size_read(inode);
+
+	num = outarg->size;
+	if (outarg->offset > file_size)
+		num = 0;
+	else if (outarg->offset + num > file_size)
+		num = file_size - outarg->offset;
+
+	num_pages = (num + offset + PAGE_SIZE - 1) >> PAGE_SHIFT;
+	num_pages = min(num_pages, FUSE_MAX_PAGES_PER_REQ);
+
+	req = fuse_get_req(fc, num_pages);
+	if (IS_ERR(req))
+		return PTR_ERR(req);
+
+	req->in.h.opcode = FUSE_NOTIFY_REPLY;
+	req->in.h.nodeid = outarg->nodeid;
+	req->in.numargs = 2;
+	req->in.argpages = 1;
+	req->page_descs[0].offset = offset;
+	req->end = fuse_retrieve_end;
+
+	index = outarg->offset >> PAGE_CACHE_SHIFT;
+
+	while (num && req->num_pages < num_pages) {
+		struct page *page;
+		unsigned int this_num;
+
+		page = find_get_page(mapping, index);
+		if (!page)
+			break;
+
+		this_num = min_t(unsigned, num, PAGE_CACHE_SIZE - offset);
+		req->pages[req->num_pages] = page;
+		req->page_descs[req->num_pages].length = this_num;
+		req->num_pages++;
+
+		offset = 0;
+		num -= this_num;
+		total_len += this_num;
+		index++;
+	}
+	req->misc.retrieve_in.offset = outarg->offset;
+	req->misc.retrieve_in.size = total_len;
+	req->in.args[0].size = sizeof(req->misc.retrieve_in);
+	req->in.args[0].value = &req->misc.retrieve_in;
+	req->in.args[1].size = total_len;
+
+	err = fuse_request_send_notify_reply(fc, req, outarg->notify_unique);
+	if (err)
+		fuse_retrieve_end(fc, req);
+
+	return err;
+}
+
+static int fuse_notify_retrieve(struct fuse_conn *fc, unsigned int size,
+				struct fuse_copy_state *cs)
+{
+	struct fuse_notify_retrieve_out outarg;
+	struct inode *inode;
+	int err;
+
+	err = -EINVAL;
+	if (size != sizeof(outarg))
+		goto copy_finish;
+
+	err = fuse_copy_one(cs, &outarg, sizeof(outarg));
+	if (err)
+		goto copy_finish;
+
+	fuse_copy_finish(cs);
+
+	down_read(&fc->killsb);
+	err = -ENOENT;
+	if (fc->sb) {
+		u64 nodeid = outarg.nodeid;
+
+		inode = ilookup5(fc->sb, nodeid, fuse_inode_eq, &nodeid);
+		if (inode) {
+			err = fuse_retrieve(fc, inode, &outarg);
+			iput(inode);
+		}
+	}
+	up_read(&fc->killsb);
+
+	return err;
+
+copy_finish:
+	fuse_copy_finish(cs);
+	return err;
+}
+
+static int fuse_notify(struct fuse_conn *fc, enum fuse_notify_code code,
+		       unsigned int size, struct fuse_copy_state *cs)
+{
+	/* Don't try to move pages (yet) */
+	cs->move_pages = 0;
+
+	switch (code) {
+	case FUSE_NOTIFY_POLL:
+		return fuse_notify_poll(fc, size, cs);
+
+	case FUSE_NOTIFY_INVAL_INODE:
+		return fuse_notify_inval_inode(fc, size, cs);
+
+	case FUSE_NOTIFY_INVAL_ENTRY:
+		return fuse_notify_inval_entry(fc, size, cs);
+
+	case FUSE_NOTIFY_STORE:
+		return fuse_notify_store(fc, size, cs);
+
+	case FUSE_NOTIFY_RETRIEVE:
+		return fuse_notify_retrieve(fc, size, cs);
+
+	case FUSE_NOTIFY_DELETE:
+		return fuse_notify_delete(fc, size, cs);
+
+	default:
+		fuse_copy_finish(cs);
+		return -EINVAL;
+	}
+}
+
+/* Look up request on processing list by unique ID */
+static struct fuse_req *request_find(struct fuse_conn *fc, u64 unique)
+{
+	struct fuse_req *req;
+
+	list_for_each_entry(req, &fc->processing, list) {
+		if (req->in.h.unique == unique || req->intr_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_do_write(struct fuse_conn *fc,
+				 struct fuse_copy_state *cs, size_t nbytes)
+{
+	int err;
+	struct fuse_req *req;
+	struct fuse_out_header oh;
+
+	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.len != nbytes)
+		goto err_finish;
+
+	/*
+	 * Zero oh.unique indicates unsolicited notification message
+	 * and error contains notification code.
+	 */
+	if (!oh.unique) {
+		err = fuse_notify(fc, oh.error, nbytes - sizeof(oh), cs);
+		return err ? err : nbytes;
+	}
+
+	err = -EINVAL;
+	if (oh.error <= -1000 || oh.error > 0)
+		goto err_finish;
+
+	spin_lock(&fc->lock);
+	err = -ENOENT;
+	if (!fc->connected)
+		goto err_unlock;
+
+	req = request_find(fc, oh.unique);
+	if (!req)
+		goto err_unlock;
+
+	if (req->aborted) {
+		spin_unlock(&fc->lock);
+		fuse_copy_finish(cs);
+		spin_lock(&fc->lock);
+		request_end(fc, req);
+		return -ENOENT;
+	}
+	/* Is it an interrupt reply? */
+	if (req->intr_unique == oh.unique) {
+		err = -EINVAL;
+		if (nbytes != sizeof(struct fuse_out_header))
+			goto err_unlock;
+
+		if (oh.error == -ENOSYS)
+			fc->no_interrupt = 1;
+		else if (oh.error == -EAGAIN)
+			queue_interrupt(fc, req);
+
+		spin_unlock(&fc->lock);
+		fuse_copy_finish(cs);
+		return nbytes;
+	}
+
+	req->state = FUSE_REQ_WRITING;
+	list_move(&req->list, &fc->io);
+	req->out.h = oh;
+	req->locked = 1;
+	cs->req = req;
+	if (!req->out.page_replace)
+		cs->move_pages = 0;
+	spin_unlock(&fc->lock);
+
+	err = copy_out_args(cs, &req->out, nbytes);
+	fuse_copy_finish(cs);
+
+	spin_lock(&fc->lock);
+	req->locked = 0;
+	if (!err) {
+		if (req->aborted)
+			err = -ENOENT;
+	} else if (!req->aborted)
+		req->out.h.error = -EIO;
+	request_end(fc, req);
+
+	return err ? err : nbytes;
+
+ err_unlock:
+	spin_unlock(&fc->lock);
+ err_finish:
+	fuse_copy_finish(cs);
+	return err;
+}
+
+static ssize_t fuse_dev_write(struct kiocb *iocb, struct iov_iter *from)
+{
+	struct fuse_copy_state cs;
+	struct fuse_conn *fc = fuse_get_conn(iocb->ki_filp);
+	if (!fc)
+		return -EPERM;
+
+	if (!iter_is_iovec(from))
+		return -EINVAL;
+
+	fuse_copy_init(&cs, fc, 0, from);
+
+	return fuse_dev_do_write(fc, &cs, iov_iter_count(from));
+}
+
+static ssize_t fuse_dev_splice_write(struct pipe_inode_info *pipe,
+				     struct file *out, loff_t *ppos,
+				     size_t len, unsigned int flags)
+{
+	unsigned nbuf;
+	unsigned idx;
+	struct pipe_buffer *bufs;
+	struct fuse_copy_state cs;
+	struct fuse_conn *fc;
+	size_t rem;
+	ssize_t ret;
+
+	fc = fuse_get_conn(out);
+	if (!fc)
+		return -EPERM;
+
+	bufs = kmalloc(pipe->buffers * sizeof(struct pipe_buffer), GFP_KERNEL);
+	if (!bufs)
+		return -ENOMEM;
+
+	pipe_lock(pipe);
+	nbuf = 0;
+	rem = 0;
+	for (idx = 0; idx < pipe->nrbufs && rem < len; idx++)
+		rem += pipe->bufs[(pipe->curbuf + idx) & (pipe->buffers - 1)].len;
+
+	ret = -EINVAL;
+	if (rem < len) {
+		pipe_unlock(pipe);
+		goto out;
+	}
+
+	rem = len;
+	while (rem) {
+		struct pipe_buffer *ibuf;
+		struct pipe_buffer *obuf;
+
+		BUG_ON(nbuf >= pipe->buffers);
+		BUG_ON(!pipe->nrbufs);
+		ibuf = &pipe->bufs[pipe->curbuf];
+		obuf = &bufs[nbuf];
+
+		if (rem >= ibuf->len) {
+			*obuf = *ibuf;
+			ibuf->ops = NULL;
+			pipe->curbuf = (pipe->curbuf + 1) & (pipe->buffers - 1);
+			pipe->nrbufs--;
+		} else {
+			ibuf->ops->get(pipe, ibuf);
+			*obuf = *ibuf;
+			obuf->flags &= ~PIPE_BUF_FLAG_GIFT;
+			obuf->len = rem;
+			ibuf->offset += obuf->len;
+			ibuf->len -= obuf->len;
+		}
+		nbuf++;
+		rem -= obuf->len;
+	}
+	pipe_unlock(pipe);
+
+	fuse_copy_init(&cs, fc, 0, NULL);
+	cs.pipebufs = bufs;
+	cs.nr_segs = nbuf;
+	cs.pipe = pipe;
+
+	if (flags & SPLICE_F_MOVE)
+		cs.move_pages = 1;
+
+	ret = fuse_dev_do_write(fc, &cs, len);
+
+	for (idx = 0; idx < nbuf; idx++) {
+		struct pipe_buffer *buf = &bufs[idx];
+		buf->ops->release(pipe, buf);
+	}
+out:
+	kfree(bufs);
+	return ret;
+}
+
+static unsigned fuse_dev_poll(struct file *file, poll_table *wait)
+{
+	unsigned mask = POLLOUT | POLLWRNORM;
+	struct fuse_conn *fc = fuse_get_conn(file);
+	if (!fc)
+		return POLLERR;
+
+	poll_wait(file, &fc->waitq, wait);
+
+	spin_lock(&fc->lock);
+	if (!fc->connected)
+		mask = POLLERR;
+	else if (request_pending(fc))
+		mask |= POLLIN | POLLRDNORM;
+	spin_unlock(&fc->lock);
+
+	return mask;
+}
+
+/*
+ * Abort all requests on the given list (pending or processing)
+ *
+ * This function releases and reacquires fc->lock
+ */
+static void end_requests(struct fuse_conn *fc, struct list_head *head)
+__releases(fc->lock)
+__acquires(fc->lock)
+{
+	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(&fc->lock);
+	}
+}
+
+/*
+ * Abort requests under I/O
+ *
+ * The requests are set to aborted and finished, and the request
+ * waiter is woken up.  This will make request_wait_answer() wait
+ * until the request is unlocked and then return.
+ *
+ * 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).
+ */
+static void end_io_requests(struct fuse_conn *fc)
+__releases(fc->lock)
+__acquires(fc->lock)
+{
+	while (!list_empty(&fc->io)) {
+		struct fuse_req *req =
+			list_entry(fc->io.next, struct fuse_req, list);
+		void (*end) (struct fuse_conn *, struct fuse_req *) = req->end;
+
+		req->aborted = 1;
+		req->out.h.error = -ECONNABORTED;
+		req->state = FUSE_REQ_FINISHED;
+		list_del_init(&req->list);
+		wake_up(&req->waitq);
+		if (end) {
+			req->end = NULL;
+			__fuse_get_request(req);
+			spin_unlock(&fc->lock);
+			wait_event(req->waitq, !req->locked);
+			end(fc, req);
+			fuse_put_request(fc, req);
+			spin_lock(&fc->lock);
+		}
+	}
+}
+
+static void end_queued_requests(struct fuse_conn *fc)
+__releases(fc->lock)
+__acquires(fc->lock)
+{
+	fc->max_background = UINT_MAX;
+	flush_bg_queue(fc);
+	end_requests(fc, &fc->pending);
+	end_requests(fc, &fc->processing);
+	while (forget_pending(fc))
+		kfree(dequeue_forget(fc, 1, NULL));
+}
+
+static void end_polls(struct fuse_conn *fc)
+{
+	struct rb_node *p;
+
+	p = rb_first(&fc->polled_files);
+
+	while (p) {
+		struct fuse_file *ff;
+		ff = rb_entry(p, struct fuse_file, polled_node);
+		wake_up_interruptible_all(&ff->poll_wait);
+
+		p = rb_next(p);
+	}
+}
+
+/*
+ * 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->aborted 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(&fc->lock);
+	if (fc->connected) {
+		fc->connected = 0;
+		fc->blocked = 0;
+		fuse_set_initialized(fc);
+		end_io_requests(fc);
+		end_queued_requests(fc);
+		end_polls(fc);
+		wake_up_all(&fc->waitq);
+		wake_up_all(&fc->blocked_waitq);
+		kill_fasync(&fc->fasync, SIGIO, POLL_IN);
+	}
+	spin_unlock(&fc->lock);
+}
+EXPORT_SYMBOL_GPL(fuse_abort_conn);
+
+int fuse_dev_release(struct inode *inode, struct file *file)
+{
+	struct fuse_conn *fc = fuse_get_conn(file);
+	if (fc) {
+		spin_lock(&fc->lock);
+		fc->connected = 0;
+		fc->blocked = 0;
+		fuse_set_initialized(fc);
+		end_queued_requests(fc);
+		end_polls(fc);
+		wake_up_all(&fc->blocked_waitq);
+		spin_unlock(&fc->lock);
+		fuse_conn_put(fc);
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(fuse_dev_release);
+
+static int fuse_dev_fasync(int fd, struct file *file, int on)
+{
+	struct fuse_conn *fc = fuse_get_conn(file);
+	if (!fc)
+		return -EPERM;
+
+	/* No locking - fasync_helper does its own locking */
+	return fasync_helper(fd, file, on, &fc->fasync);
+}
+
+const struct file_operations fuse_dev_operations = {
+	.owner		= THIS_MODULE,
+	.open		= fuse_dev_open,
+	.llseek		= no_llseek,
+	.read_iter	= fuse_dev_read,
+	.splice_read	= fuse_dev_splice_read,
+	.write_iter	= fuse_dev_write,
+	.splice_write	= fuse_dev_splice_write,
+	.poll		= fuse_dev_poll,
+	.release	= fuse_dev_release,
+	.fasync		= fuse_dev_fasync,
+};
+EXPORT_SYMBOL_GPL(fuse_dev_operations);
+
+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);
+	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);
+}