Commit 0d8e84b0 authored by Miklos Szeredi's avatar Miklos Szeredi
Browse files

fuse: simplify request abort 



 - don't end the request while req->locked is true

 - make unlock_request() return an error if the connection was aborted

Signed-off-by: default avatarMiklos Szeredi <mszeredi@suse.cz>
Reviewed-by: default avatarAshish Samant <ashish.samant@oracle.com>
parent ccd0a0bd

fs/fuse/dev.c

+46 −73
Original line number Diff line number Diff line
@@ -382,8 +382,8 @@ __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);

	list_del_init(&req->list);

	list_del_init(&req->intr_entry);

	req->state = FUSE_REQ_FINISHED;

	if (req->background) {

		req->background = 0;
@@ -439,8 +439,6 @@ __acquires(fc->lock) 
		/* Any signal may interrupt this */

		wait_answer_interruptible(fc, req);



		if (req->aborted)

			goto aborted;

		if (req->state == FUSE_REQ_FINISHED)

			return;
@@ -457,8 +455,6 @@ __acquires(fc->lock) 
		wait_answer_interruptible(fc, req);

		restore_sigs(&oldset);



		if (req->aborted)

			goto aborted;

		if (req->state == FUSE_REQ_FINISHED)

			return;
@@ -478,22 +474,6 @@ __acquires(fc->lock) 
	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)
@@ -690,19 +670,21 @@ static int lock_request(struct fuse_conn *fc, struct fuse_req *req) 
}



/*

 * Unlock request.  If it was aborted during being locked, the

 * requester thread is currently waiting for it to be unlocked, so

 * wake it up.

 * Unlock request.  If it was aborted while locked, caller is responsible

 * for unlocking and ending the request.

 */

static void unlock_request(struct fuse_conn *fc, struct fuse_req *req)

static int unlock_request(struct fuse_conn *fc, struct fuse_req *req)

{

	int err = 0;

	if (req) {

		spin_lock(&fc->lock);

		req->locked = 0;

		if (req->aborted)

			wake_up(&req->waitq);

			err = -ENOENT;

		else

			req->locked = 0;

		spin_unlock(&fc->lock);

	}

	return err;

}



struct fuse_copy_state {
@@ -759,7 +741,10 @@ static int fuse_copy_fill(struct fuse_copy_state *cs) 
	struct page *page;

	int err;



	unlock_request(cs->fc, cs->req);

	err = unlock_request(cs->fc, cs->req);

	if (err)

		return err;



	fuse_copy_finish(cs);

	if (cs->pipebufs) {

		struct pipe_buffer *buf = cs->pipebufs;
@@ -859,7 +844,10 @@ static int fuse_try_move_page(struct fuse_copy_state *cs, struct page **pagep) 
	struct page *newpage;

	struct pipe_buffer *buf = cs->pipebufs;



	unlock_request(cs->fc, cs->req);

	err = unlock_request(cs->fc, cs->req);

	if (err)

		return err;



	fuse_copy_finish(cs);



	err = buf->ops->confirm(cs->pipe, buf);
@@ -949,11 +937,15 @@ static int fuse_ref_page(struct fuse_copy_state *cs, struct page *page, 
			 unsigned offset, unsigned count)

{

	struct pipe_buffer *buf;

	int err;



	if (cs->nr_segs == cs->pipe->buffers)

		return -EIO;



	unlock_request(cs->fc, cs->req);

	err = unlock_request(cs->fc, cs->req);

	if (err)

		return err;



	fuse_copy_finish(cs);



	buf = cs->pipebufs;
@@ -1318,7 +1310,7 @@ static ssize_t fuse_dev_do_read(struct fuse_conn *fc, struct file *file, 
	fuse_copy_finish(cs);

	spin_lock(&fc->lock);

	req->locked = 0;

	if (req->aborted) {

	if (!fc->connected) {

		request_end(fc, req);

		return -ENODEV;

	}
@@ -1910,13 +1902,6 @@ static ssize_t fuse_dev_do_write(struct fuse_conn *fc, 
	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;
@@ -1947,10 +1932,9 @@ static ssize_t fuse_dev_do_write(struct fuse_conn *fc, 


	spin_lock(&fc->lock);

	req->locked = 0;

	if (!err) {

		if (req->aborted)

	if (!fc->connected)

		err = -ENOENT;

	} else if (!req->aborted)

	else if (err)

		req->out.h.error = -EIO;

	request_end(fc, req);
@@ -2097,39 +2081,33 @@ __acquires(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.

 * Separate out unlocked requests, they should be finished off immediately.

 * Locked requests will be finished after unlock; see unlock_request().

 *

 * 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).

 * Next finish off the unlocked requests.  It is possible that some request will

 * finish before we can.  This is OK, the request will in that case be removed

 * from the list before we touch it.

 */

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;

	struct fuse_req *req, *next;

	LIST_HEAD(to_end);



		req->aborted = 1;

	list_for_each_entry_safe(req, next, &fc->io, list) {

		req->out.h.error = -ECONNABORTED;

		req->state = FUSE_REQ_FINISHED;

		list_del_init(&req->list);

		wake_up(&req->waitq);

		if (end) {

			req->end = NULL;

		req->aborted = 1;

		if (!req->locked)

			list_move(&req->list, &to_end);

	}

	while (!list_empty(&to_end)) {

		req = list_first_entry(&to_end, struct fuse_req, list);

		__fuse_get_request(req);

			spin_unlock(&fc->lock);

			wait_event(req->waitq, !req->locked);

			end(fc, req);

			fuse_put_request(fc, req);

		request_end(fc, req);

		spin_lock(&fc->lock);

	}

}

}



static void end_queued_requests(struct fuse_conn *fc)

__releases(fc->lock)
@@ -2169,13 +2147,8 @@ static void end_polls(struct fuse_conn *fc) 
 * 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.

 * Request progression from one list to the next is prevented by

 * fc->connected being false.

 */

void fuse_abort_conn(struct fuse_conn *fc)

{