3 files changed, 38 insertions, 4 deletions

diff --git a/fs/fuse/dev.c b/fs/fuse/dev.c
index 4dc104c0e95..6c740f86066 100644
--- a/fs/fuse/dev.c
+++ b/fs/fuse/dev.c
@@ -90,7 +90,17 @@ static void __fuse_put_request(struct fuse_req *req)
 
 struct fuse_req *fuse_get_req(struct fuse_conn *fc)
 {
-	struct fuse_req *req = fuse_request_alloc();
+	struct fuse_req *req;
+	sigset_t oldset;
+	int err;
+
+	block_sigs(&oldset);
+	err = wait_event_interruptible(fc->blocked_waitq, !fc->blocked);
+	restore_sigs(&oldset);
+	if (err)
+		return ERR_PTR(-EINTR);
+
+	req = fuse_request_alloc();
 	if (!req)
 		return ERR_PTR(-ENOMEM);
 
@@ -118,6 +128,11 @@ void fuse_release_background(struct fuse_conn *fc, struct fuse_req *req)
 		fput(req->file);
 	spin_lock(&fc->lock);
 	list_del(&req->bg_entry);
+	if (fc->num_background == FUSE_MAX_BACKGROUND) {
+		fc->blocked = 0;
+		wake_up_all(&fc->blocked_waitq);
+	}
+	fc->num_background--;
 	spin_unlock(&fc->lock);
 }
 
@@ -195,6 +210,9 @@ static void background_request(struct fuse_conn *fc, struct fuse_req *req)
 {
 	req->background = 1;
 	list_add(&req->bg_entry, &fc->background);
+	fc->num_background++;
+	if (fc->num_background == FUSE_MAX_BACKGROUND)
+		fc->blocked = 1;
 	if (req->inode)
 		req->inode = igrab(req->inode);
 	if (req->inode2)
@@ -288,6 +306,7 @@ void request_send(struct fuse_conn *fc, struct fuse_req *req)
 static void request_send_nowait(struct fuse_conn *fc, struct fuse_req *req)
 {
 	spin_lock(&fc->lock);
+	background_request(fc, req);
 	if (fc->connected) {
 		queue_request(fc, req);
 		spin_unlock(&fc->lock);
@@ -306,9 +325,6 @@ void request_send_noreply(struct fuse_conn *fc, struct fuse_req *req)
 void request_send_background(struct fuse_conn *fc, struct fuse_req *req)
 {
 	req->isreply = 1;
-	spin_lock(&fc->lock);
-	background_request(fc, req);
-	spin_unlock(&fc->lock);
 	request_send_nowait(fc, req);
 }
 
diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
index 242e69cb125..19c7185a754 100644
--- a/fs/fuse/fuse_i.h
+++ b/fs/fuse/fuse_i.h
@@ -18,6 +18,9 @@
 /** Max number of pages that can be used in a single read request */
 #define FUSE_MAX_PAGES_PER_REQ 32
 
+/** Maximum number of outstanding background requests */
+#define FUSE_MAX_BACKGROUND 10
+
 /** It could be as large as PATH_MAX, but would that have any uses? */
 #define FUSE_NAME_MAX 1024
 
@@ -241,6 +244,17 @@ struct fuse_conn {
 	    interrupted request) */
 	struct list_head background;
 
+	/** Number of requests currently in the background */
+	unsigned num_background;
+
+	/** Flag indicating if connection is blocked.  This will be
+	    the case before the INIT reply is received, and if there
+	    are too many outstading backgrounds requests */
+	int blocked;
+
+	/** waitq for blocked connection */
+	wait_queue_head_t blocked_waitq;
+
 	/** RW semaphore for exclusion with fuse_put_super() */
 	struct rw_semaphore sbput_sem;
 
diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c
index 824ebbc428e..fd34037b058 100644
--- a/fs/fuse/inode.c
+++ b/fs/fuse/inode.c
@@ -381,6 +381,7 @@ static struct fuse_conn *new_conn(void)
 	if (fc) {
 		spin_lock_init(&fc->lock);
 		init_waitqueue_head(&fc->waitq);
+		init_waitqueue_head(&fc->blocked_waitq);
 		INIT_LIST_HEAD(&fc->pending);
 		INIT_LIST_HEAD(&fc->processing);
 		INIT_LIST_HEAD(&fc->io);
@@ -392,6 +393,7 @@ static struct fuse_conn *new_conn(void)
 		fc->bdi.ra_pages = (VM_MAX_READAHEAD * 1024) / PAGE_CACHE_SIZE;
 		fc->bdi.unplug_io_fn = default_unplug_io_fn;
 		fc->reqctr = 0;
+		fc->blocked = 1;
 	}
 	return fc;
 }
@@ -438,6 +440,8 @@ static void process_init_reply(struct fuse_conn *fc, struct fuse_req *req)
 		fc->max_write = arg->minor < 5 ? 4096 : arg->max_write;
 	}
 	fuse_put_request(fc, req);
+	fc->blocked = 0;
+	wake_up_all(&fc->blocked_waitq);
 }
 
 static void fuse_send_init(struct fuse_conn *fc, struct fuse_req *req)