fuse: implement exclusive wakeup for blocked_waitq

[karo-tx-linux.git] / fs / fuse / dev.c

diff --git a/fs/fuse/dev.c b/fs/fuse/dev.c
index d692b85115bd57590867b3a39924f171fd9d983d..3673105889628714a4f5c02fcfa73f0301ba3320 100644 (file)
--- a/fs/fuse/dev.c
+++ b/fs/fuse/dev.c
@@ -147,7 +147,7 @@ static struct fuse_req *__fuse_get_req(struct fuse_conn *fc, unsigned npages,
                int intr;
 
                block_sigs(&oldset);
-               intr = wait_event_interruptible(fc->blocked_waitq,
+               intr = wait_event_interruptible_exclusive(fc->blocked_waitq,
                                !fuse_block_alloc(fc, for_background));
                restore_sigs(&oldset);
                err = -EINTR;
@@ -161,8 +161,11 @@ static struct fuse_req *__fuse_get_req(struct fuse_conn *fc, unsigned npages,
 
        req = fuse_request_alloc(npages);
        err = -ENOMEM;
-       if (!req)
+       if (!req) {
+               if (for_background)
+                       wake_up(&fc->blocked_waitq);
                goto out;
+       }
 
        fuse_req_init_context(req);
        req->waiting = 1;
@@ -262,6 +265,17 @@ struct fuse_req *fuse_get_req_nofail_nopages(struct fuse_conn *fc,
 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);
 
@@ -359,10 +373,15 @@ __releases(fc->lock)
        list_del(&req->intr_entry);
        req->state = FUSE_REQ_FINISHED;
        if (req->background) {
-               if (fc->num_background == fc->max_background) {
+               req->background = 0;
+
+               if (fc->num_background == fc->max_background)
                        fc->blocked = 0;
-                       wake_up_all(&fc->blocked_waitq);
-               }
+
+               /* Wake up next waiter, if any */
+               if (!fc->blocked)
+                       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);