4 files changed, 32 insertions, 13 deletions

diff --git a/fs/fuse/dev.c b/fs/fuse/dev.c
index f58ecbc416c8..b152761c1bf6 100644
--- a/fs/fuse/dev.c
+++ b/fs/fuse/dev.c
@@ -250,7 +250,7 @@ static void queue_request(struct fuse_conn *fc, struct fuse_req *req)
 
 static void flush_bg_queue(struct fuse_conn *fc)
 {
-        while (fc->active_background < FUSE_MAX_BACKGROUND &&
+        while (fc->active_background < fc->max_background &&
                !list_empty(&fc->bg_queue)) {
                 struct fuse_req *req;
 
@@ -280,11 +280,11 @@ __releases(&fc->lock)
         list_del(&req->intr_entry);
         req->state = FUSE_REQ_FINISHED;
         if (req->background) {
-                if (fc->num_background == FUSE_MAX_BACKGROUND) {
+                if (fc->num_background == fc->max_background) {
                         fc->blocked = 0;
                         wake_up_all(&fc->blocked_waitq);
                 }
-                if (fc->num_background == FUSE_CONGESTION_THRESHOLD &&
+                if (fc->num_background == fc->congestion_threshold &&
                     fc->connected && fc->bdi_initialized) {
                         clear_bdi_congested(&fc->bdi, READ);
                         clear_bdi_congested(&fc->bdi, WRITE);
@@ -410,9 +410,9 @@ static void fuse_request_send_nowait_locked(struct fuse_conn *fc,
 {
         req->background = 1;
         fc->num_background++;
-        if (fc->num_background == FUSE_MAX_BACKGROUND)
+        if (fc->num_background == fc->max_background)
                 fc->blocked = 1;
-        if (fc->num_background == FUSE_CONGESTION_THRESHOLD &&
+        if (fc->num_background == fc->congestion_threshold &&
             fc->bdi_initialized) {
                 set_bdi_congested(&fc->bdi, READ);
                 set_bdi_congested(&fc->bdi, WRITE);
diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
index 52b641fc0faf..6bcfab04396f 100644
--- a/fs/fuse/fuse_i.h
+++ b/fs/fuse/fuse_i.h
@@ -25,12 +25,6 @@
 /** 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 12
-
-/** Congestion starts at 75% of maximum */
-#define FUSE_CONGESTION_THRESHOLD (FUSE_MAX_BACKGROUND * 75 / 100)
-
 /** Bias for fi->writectr, meaning new writepages must not be sent */
 #define FUSE_NOWRITE INT_MIN
 
@@ -349,6 +343,12 @@ struct fuse_conn {
         /** rbtree of fuse_files waiting for poll events indexed by ph */
         struct rb_root polled_files;
 
+        /** Maximum number of outstanding background requests */
+        unsigned max_background;
+
+        /** Number of background requests at which congestion starts */
+        unsigned congestion_threshold;
+
         /** Number of requests currently in the background */
         unsigned num_background;
 
diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c
index f91ccc4a189d..9aa6f46d0c32 100644
--- a/fs/fuse/inode.c
+++ b/fs/fuse/inode.c
@@ -32,6 +32,12 @@ DEFINE_MUTEX(fuse_mutex);
 
 #define FUSE_DEFAULT_BLKSIZE 512
 
+/** Maximum number of outstanding background requests */
+#define FUSE_DEFAULT_MAX_BACKGROUND 12
+
+/** Congestion starts at 75% of maximum */
+#define FUSE_DEFAULT_CONGESTION_THRESHOLD (FUSE_DEFAULT_MAX_BACKGROUND * 3 / 4)
+
 struct fuse_mount_data {
         int fd;
         unsigned rootmode;
@@ -517,6 +523,8 @@ void fuse_conn_init(struct fuse_conn *fc)
         INIT_LIST_HEAD(&fc->bg_queue);
         INIT_LIST_HEAD(&fc->entry);
         atomic_set(&fc->num_waiting, 0);
+        fc->max_background = FUSE_DEFAULT_MAX_BACKGROUND;
+        fc->congestion_threshold = FUSE_DEFAULT_CONGESTION_THRESHOLD;
         fc->khctr = 0;
         fc->polled_files = RB_ROOT;
         fc->reqctr = 0;
@@ -736,6 +744,12 @@ static void process_init_reply(struct fuse_conn *fc, struct fuse_req *req)
         else {
                 unsigned long ra_pages;
 
+                if (arg->minor >= 13) {
+                        if (arg->max_background)
+                                fc->max_background = arg->max_background;
+                        if (arg->congestion_threshold)
+                                fc->congestion_threshold = arg->congestion_threshold;
+                }
                 if (arg->minor >= 6) {
                         ra_pages = arg->max_readahead / PAGE_CACHE_SIZE;
                         if (arg->flags & FUSE_ASYNC_READ)
diff --git a/include/linux/fuse.h b/include/linux/fuse.h
index cf593bf9fd32..b3700f0ac268 100644
--- a/include/linux/fuse.h
+++ b/include/linux/fuse.h
@@ -30,6 +30,10 @@
  *  - add umask flag to input argument of open, mknod and mkdir
  *  - add notification messages for invalidation of inodes and
  *    directory entries
+ *
+ * 7.13
+ *  - make max number of background requests and congestion threshold
+ *    tunables
  */
 
 #ifndef _LINUX_FUSE_H
@@ -41,7 +45,7 @@
 #define FUSE_KERNEL_VERSION 7
 
 /** Minor version number of this interface */
-#define FUSE_KERNEL_MINOR_VERSION 12
+#define FUSE_KERNEL_MINOR_VERSION 13
 
 /** The node ID of the root inode */
 #define FUSE_ROOT_ID 1
@@ -427,7 +431,8 @@ struct fuse_init_out {
         __u32   minor;
         __u32   max_readahead;
         __u32   flags;
-        __u32   unused;
+        __u16   max_background;
+        __u16   congestion_threshold;
         __u32   max_write;
 };