fuse: split off fch->lock from fc->lock

And document which members they protect.

end_polls() is called with both, outer fch->lock is probably unnecessary,
but doesn't hurt for now.

Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>

fs/fuse/dev.c

@@ -354,6 +354,7 @@ struct fuse_chan *fuse_chan_new(void)
 	if (!fch)
 		return NULL;
 
+	spin_lock_init(&fch->lock);
 	INIT_LIST_HEAD(&fch->devices);
 	spin_lock_init(&fch->bg_lock);
 	INIT_LIST_HEAD(&fch->bg_queue);
@@ -418,7 +419,7 @@ void fuse_dev_install(struct fuse_dev *fud, struct fuse_conn *fc)
 {
 	struct fuse_conn *old_fc;
 
-	spin_lock(&fc->lock);
+	spin_lock(&fc->chan->lock);
 	/*
 	 * Pairs with:
 	 *  - xchg() in fuse_dev_release()
@@ -436,7 +437,7 @@ void fuse_dev_install(struct fuse_dev *fud, struct fuse_conn *fc)
 		list_add_tail(&fud->entry, &fc->chan->devices);
 		fuse_conn_get(fc);
 	}
-	spin_unlock(&fc->lock);
+	spin_unlock(&fc->chan->lock);
 }
 EXPORT_SYMBOL_GPL(fuse_dev_install);
 
@@ -463,9 +464,9 @@ void fuse_dev_put(struct fuse_dev *fud)
 	fc = fuse_dev_fc_get(fud);
 	if (fc && fc != FUSE_DEV_FC_DISCONNECTED) {
 		/* This is the virtiofs case (fuse_dev_release() not called) */
-		spin_lock(&fc->lock);
+		spin_lock(&fc->chan->lock);
 		list_del(&fud->entry);
-		spin_unlock(&fc->lock);
+		spin_unlock(&fc->chan->lock);
 
 		fuse_conn_put(fc);
 	}
@@ -2060,9 +2061,9 @@ static void fuse_resend(struct fuse_conn *fc)
 	LIST_HEAD(to_queue);
 	unsigned int i;
 
-	spin_lock(&fc->lock);
+	spin_lock(&fc->chan->lock);
 	if (!fc->chan->connected) {
-		spin_unlock(&fc->lock);
+		spin_unlock(&fc->chan->lock);
 		return;
 	}
 
@@ -2074,7 +2075,7 @@ static void fuse_resend(struct fuse_conn *fc)
 			list_splice_tail_init(&fpq->processing[i], &to_queue);
 		spin_unlock(&fpq->lock);
 	}
-	spin_unlock(&fc->lock);
+	spin_unlock(&fc->chan->lock);
 
 	list_for_each_entry_safe(req, next, &to_queue, list) {
 		set_bit(FR_PENDING, &req->flags);
@@ -2498,6 +2499,7 @@ static void end_polls(struct fuse_conn *fc)
 {
 	struct rb_node *p;
 
+	spin_lock(&fc->lock);
 	p = rb_first(&fc->polled_files);
 
 	while (p) {
@@ -2507,6 +2509,7 @@ static void end_polls(struct fuse_conn *fc)
 
 		p = rb_next(p);
 	}
+	spin_unlock(&fc->lock);
 }
 
 /*
@@ -2531,7 +2534,7 @@ void fuse_abort_conn(struct fuse_conn *fc)
 {
 	struct fuse_iqueue *fiq = &fc->chan->iq;
 
-	spin_lock(&fc->lock);
+	spin_lock(&fc->chan->lock);
 	if (fc->chan->connected) {
 		struct fuse_dev *fud;
 		struct fuse_req *req, *next;
@@ -2586,17 +2589,17 @@ void fuse_abort_conn(struct fuse_conn *fc)
 		kill_fasync(&fiq->fasync, SIGIO, POLL_IN);
 		end_polls(fc);
 		wake_up_all(&fc->chan->blocked_waitq);
-		spin_unlock(&fc->lock);
+		spin_unlock(&fc->chan->lock);
 
 		fuse_dev_end_requests(&to_end);
 
 		/*
-		 * fc->lock must not be taken to avoid conflicts with io-uring
+		 * fc->chan->lock must not be taken to avoid conflicts with io-uring
 		 * locks
 		 */
 		fuse_uring_abort(fc);
 	} else {
-		spin_unlock(&fc->lock);
+		spin_unlock(&fc->chan->lock);
 	}
 }
 EXPORT_SYMBOL_GPL(fuse_abort_conn);
@@ -2630,11 +2633,11 @@ int fuse_dev_release(struct inode *inode, struct file *file)
 
 		fuse_dev_end_requests(&to_end);
 
-		spin_lock(&fc->lock);
+		spin_lock(&fc->chan->lock);
 		list_del(&fud->entry);
 		/* Are we the last open device? */
 		last = list_empty(&fc->chan->devices);
-		spin_unlock(&fc->lock);
+		spin_unlock(&fc->chan->lock);
 
 		if (last) {
 			WARN_ON(fc->chan->iq.fasync != NULL);

fs/fuse/dev_uring.c

@@ -243,14 +243,14 @@ static struct fuse_ring *fuse_uring_create(struct fuse_conn *fc)
 	max_payload_size = max(FUSE_MIN_READ_BUFFER, fc->max_write);
 	max_payload_size = max(max_payload_size, fc->max_pages * PAGE_SIZE);
 
-	spin_lock(&fc->lock);
+	spin_lock(&fc->chan->lock);
 	if (!fc->chan->connected) {
-		spin_unlock(&fc->lock);
+		spin_unlock(&fc->chan->lock);
 		goto out_err;
 	}
 	if (fc->chan->ring) {
 		/* race, another thread created the ring in the meantime */
-		spin_unlock(&fc->lock);
+		spin_unlock(&fc->chan->lock);
 		res = fc->chan->ring;
 		goto out_err;
 	}
@@ -262,7 +262,7 @@ static struct fuse_ring *fuse_uring_create(struct fuse_conn *fc)
 	ring->max_payload_sz = max_payload_size;
 	smp_store_release(&fc->chan->ring, ring);
 
-	spin_unlock(&fc->lock);
+	spin_unlock(&fc->chan->lock);
 	return ring;
 
 out_err:
@@ -302,9 +302,9 @@ static struct fuse_ring_queue *fuse_uring_create_queue(struct fuse_ring *ring,
 	queue->fpq.processing = pq;
 	fuse_pqueue_init(&queue->fpq);
 
-	spin_lock(&fc->lock);
+	spin_lock(&fc->chan->lock);
 	if (ring->queues[qid]) {
-		spin_unlock(&fc->lock);
+		spin_unlock(&fc->chan->lock);
 		kfree(queue->fpq.processing);
 		kfree(queue);
 		return ring->queues[qid];
@@ -314,7 +314,7 @@ static struct fuse_ring_queue *fuse_uring_create_queue(struct fuse_ring *ring,
 	 * write_once and lock as the caller mostly doesn't take the lock at all
 	 */
 	WRITE_ONCE(ring->queues[qid], queue);
-	spin_unlock(&fc->lock);
+	spin_unlock(&fc->chan->lock);
 
 	return queue;
 }
@@ -1008,16 +1008,16 @@ static int fuse_uring_do_register(struct fuse_ring_ent *ent,
 	struct fuse_conn *fc = ring->fc;
 	struct fuse_iqueue *fiq = &fc->chan->iq;
 
-	spin_lock(&fc->lock);
+	spin_lock(&fc->chan->lock);
 	/* abort teardown path is running or has run */
 	if (!fc->chan->connected) {
-		spin_unlock(&fc->lock);
+		spin_unlock(&fc->chan->lock);
 		if (atomic_dec_and_test(&ring->queue_refs))
 			wake_up_all(&ring->stop_waitq);
 		kfree(ent);
 		return -ECONNABORTED;
 	}
-	spin_unlock(&fc->lock);
+	spin_unlock(&fc->chan->lock);
 
 	fuse_uring_prepare_cancel(cmd, issue_flags, ent);
 

fs/fuse/fuse_dev_i.h

@@ -88,6 +88,14 @@ struct fuse_iqueue {
 };
 
 struct fuse_chan {
+	/** Lock protecting:
+	    - devices
+	    - connected
+	    - ring
+	    - ring->queues[qid]
+	 */
+	spinlock_t lock;
+
 	/** Input queue */
 	struct fuse_iqueue iq;
 

fs/fuse/fuse_i.h

@@ -421,7 +421,7 @@ enum fuse_req_flag {
  *
  * .waitq.lock protects the following fields:
  *   - FR_ABORTED
- *   - FR_LOCKED (may also be modified under fc->lock, tested under both)
+ *   - FR_LOCKED (may also be modified under fpq->lock, tested under both)
  */
 struct fuse_req {
 	/** This can be on either pending processing or io lists in
@@ -520,7 +520,11 @@ struct fuse_sync_bucket {
  * fuse_mount is destroyed.
  */
 struct fuse_conn {
-	/** Lock protecting accessess to  members of this structure */
+	/** Lock protecting:
+	    - polled_files
+	    - backing_files_map
+	    - curr_bucket
+	 */
 	spinlock_t lock;
 
 	/** Refcount */

fs/fuse/req_timeout.c

@@ -89,9 +89,9 @@ static void fuse_check_timeout(struct work_struct *work)
 	if (expired)
 		goto abort_conn;
 
-	spin_lock(&fc->lock);
+	spin_lock(&fc->chan->lock);
 	if (!fc->chan->connected) {
-		spin_unlock(&fc->lock);
+		spin_unlock(&fc->chan->lock);
 		return;
 	}
 	list_for_each_entry(fud, &fc->chan->devices, entry) {
@@ -100,13 +100,13 @@ static void fuse_check_timeout(struct work_struct *work)
 		if (fuse_request_expired(fc, &fpq->io) ||
 		    fuse_fpq_processing_expired(fc, fpq->processing)) {
 			spin_unlock(&fpq->lock);
-			spin_unlock(&fc->lock);
+			spin_unlock(&fc->chan->lock);
 			goto abort_conn;
 		}
 
 		spin_unlock(&fpq->lock);
 	}
-	spin_unlock(&fc->lock);
+	spin_unlock(&fc->chan->lock);
 
 	if (fuse_uring_request_expired(fc))
 		goto abort_conn;