fuse: separate pqueue for clones

Make each fuse device clone refer to a separate processing queue.  The only
constraint on userspace code is that the request answer must be written to
the same device clone as it was read off.
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>

fs/fuse/dev.c

@@ -1232,12 +1232,13 @@ __releases(fiq->waitq.lock)
  * 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,
+static ssize_t fuse_dev_do_read(struct fuse_dev *fud, struct file *file,
 				struct fuse_copy_state *cs, size_t nbytes)
 {
 	ssize_t err;
+	struct fuse_conn *fc = fud->fc;
 	struct fuse_iqueue *fiq = &fc->iq;
-	struct fuse_pqueue *fpq = &fc->pq;
+	struct fuse_pqueue *fpq = &fud->pq;
 	struct fuse_req *req;
 	struct fuse_in *in;
 	unsigned reqsize;
@@ -1358,7 +1359,7 @@ static ssize_t fuse_dev_read(struct kiocb *iocb, struct iov_iter *to)
 
 	fuse_copy_init(&cs, 1, to);
 
-	return fuse_dev_do_read(fud->fc, file, &cs, iov_iter_count(to));
+	return fuse_dev_do_read(fud, file, &cs, iov_iter_count(to));
 }
 
 static ssize_t fuse_dev_splice_read(struct file *in, loff_t *ppos,
@@ -1382,7 +1383,7 @@ static ssize_t fuse_dev_splice_read(struct file *in, loff_t *ppos,
 	fuse_copy_init(&cs, 1, NULL);
 	cs.pipebufs = bufs;
 	cs.pipe = pipe;
-	ret = fuse_dev_do_read(fud->fc, in, &cs, len);
+	ret = fuse_dev_do_read(fud, in, &cs, len);
 	if (ret < 0)
 		goto out;
 
@@ -1862,11 +1863,12 @@ static int copy_out_args(struct fuse_copy_state *cs, struct fuse_out *out,
  * 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,
+static ssize_t fuse_dev_do_write(struct fuse_dev *fud,
 				 struct fuse_copy_state *cs, size_t nbytes)
 {
 	int err;
-	struct fuse_pqueue *fpq = &fc->pq;
+	struct fuse_conn *fc = fud->fc;
+	struct fuse_pqueue *fpq = &fud->pq;
 	struct fuse_req *req;
 	struct fuse_out_header oh;
 
@@ -1966,7 +1968,7 @@ static ssize_t fuse_dev_write(struct kiocb *iocb, struct iov_iter *from)
 
 	fuse_copy_init(&cs, 0, from);
 
-	return fuse_dev_do_write(fud->fc, &cs, iov_iter_count(from));
+	return fuse_dev_do_write(fud, &cs, iov_iter_count(from));
 }
 
 static ssize_t fuse_dev_splice_write(struct pipe_inode_info *pipe,
@@ -2037,7 +2039,7 @@ static ssize_t fuse_dev_splice_write(struct pipe_inode_info *pipe,
 	if (flags & SPLICE_F_MOVE)
 		cs.move_pages = 1;
 
-	ret = fuse_dev_do_write(fud->fc, &cs, len);
+	ret = fuse_dev_do_write(fud, &cs, len);
 
 	for (idx = 0; idx < nbuf; idx++) {
 		struct pipe_buffer *buf = &bufs[idx];
@@ -2124,10 +2126,10 @@ static void end_polls(struct fuse_conn *fc)
 void fuse_abort_conn(struct fuse_conn *fc)
 {
 	struct fuse_iqueue *fiq = &fc->iq;
-	struct fuse_pqueue *fpq = &fc->pq;
 
 	spin_lock(&fc->lock);
 	if (fc->connected) {
+		struct fuse_dev *fud;
 		struct fuse_req *req, *next;
 		LIST_HEAD(to_end1);
 		LIST_HEAD(to_end2);
@@ -2135,6 +2137,9 @@ void fuse_abort_conn(struct fuse_conn *fc)
 		fc->connected = 0;
 		fc->blocked = 0;
 		fuse_set_initialized(fc);
+		list_for_each_entry(fud, &fc->devices, entry) {
+			struct fuse_pqueue *fpq = &fud->pq;
+
 			spin_lock(&fpq->lock);
 			fpq->connected = 0;
 			list_for_each_entry_safe(req, next, &fpq->io, list) {
@@ -2149,6 +2154,7 @@ void fuse_abort_conn(struct fuse_conn *fc)
 			}
 			list_splice_init(&fpq->processing, &to_end2);
 			spin_unlock(&fpq->lock);
+		}
 		fc->max_background = UINT_MAX;
 		flush_bg_queue(fc);
 
@@ -2183,13 +2189,17 @@ int fuse_dev_release(struct inode *inode, struct file *file)
 
 	if (fud) {
 		struct fuse_conn *fc = fud->fc;
+		struct fuse_pqueue *fpq = &fud->pq;
 
-		WARN_ON(!list_empty(&fc->pq.io));
+		WARN_ON(!list_empty(&fpq->io));
+		end_requests(fc, &fpq->processing);
+		/* Are we the last open device? */
+		if (atomic_dec_and_test(&fc->dev_count)) {
 			WARN_ON(fc->iq.fasync != NULL);
 			fuse_abort_conn(fc);
+		}
 		fuse_dev_free(fud);
 	}
-
 	return 0;
 }
 EXPORT_SYMBOL_GPL(fuse_dev_release);
@@ -2217,6 +2227,7 @@ static int fuse_device_clone(struct fuse_conn *fc, struct file *new)
 		return -ENOMEM;
 
 	new->private_data = fud;
+	atomic_inc(&fc->dev_count);
 
 	return 0;
 }

fs/fuse/fuse_i.h

@@ -424,6 +424,9 @@ struct fuse_dev {
 	/** Fuse connection for this device */
 	struct fuse_conn *fc;
 
+	/** Processing queue */
+	struct fuse_pqueue pq;
+
 	/** list entry on fc->devices */
 	struct list_head entry;
 };
@@ -442,6 +445,9 @@ struct fuse_conn {
 	/** Refcount */
 	atomic_t count;
 
+	/** Number of fuse_dev's */
+	atomic_t dev_count;
+
 	struct rcu_head rcu;
 
 	/** The user id for this mount */
@@ -462,9 +468,6 @@ struct fuse_conn {
 	/** Input queue */
 	struct fuse_iqueue iq;
 
-	/** Processing queue */
-	struct fuse_pqueue pq;
-
 	/** The next unique kernel file handle */
 	u64 khctr;
 

fs/fuse/inode.c

@@ -592,10 +592,10 @@ void fuse_conn_init(struct fuse_conn *fc)
 	spin_lock_init(&fc->lock);
 	init_rwsem(&fc->killsb);
 	atomic_set(&fc->count, 1);
+	atomic_set(&fc->dev_count, 1);
 	init_waitqueue_head(&fc->blocked_waitq);
 	init_waitqueue_head(&fc->reserved_req_waitq);
 	fuse_iqueue_init(&fc->iq);
-	fuse_pqueue_init(&fc->pq);
 	INIT_LIST_HEAD(&fc->bg_queue);
 	INIT_LIST_HEAD(&fc->entry);
 	INIT_LIST_HEAD(&fc->devices);
@@ -999,6 +999,7 @@ struct fuse_dev *fuse_dev_alloc(struct fuse_conn *fc)
 	fud = kzalloc(sizeof(struct fuse_dev), GFP_KERNEL);
 	if (fud) {
 		fud->fc = fuse_conn_get(fc);
+		fuse_pqueue_init(&fud->pq);
 
 		spin_lock(&fc->lock);
 		list_add_tail(&fud->entry, &fc->devices);