2 files changed, 29 insertions, 2 deletions

diff --git a/fs/fuse/dev.c b/fs/fuse/dev.c
index 225388f54ae7..ffd670bb8c8c 100644
--- a/fs/fuse/dev.c
+++ b/fs/fuse/dev.c
@@ -816,6 +816,15 @@ static ssize_t fuse_dev_read(struct kiocb *iocb, const struct iovec *iov,
         return err;
 }
 
+static int fuse_notify(struct fuse_conn *fc, enum fuse_notify_code code,
+                       unsigned int size, struct fuse_copy_state *cs)
+{
+        switch (code) {
+        default:
+                return -EINVAL;
+        }
+}
+
 /* Look up request on processing list by unique ID */
 static struct fuse_req *request_find(struct fuse_conn *fc, u64 unique)
 {
@@ -879,9 +888,23 @@ static ssize_t fuse_dev_write(struct kiocb *iocb, const struct iovec *iov,
         err = fuse_copy_one(&cs, &oh, sizeof(oh));
         if (err)
                 goto err_finish;
+
+        err = -EINVAL;
+        if (oh.len != nbytes)
+                goto err_finish;
+
+        /*
+         * Zero oh.unique indicates unsolicited notification message
+         * and error contains notification code.
+         */
+        if (!oh.unique) {
+                err = fuse_notify(fc, oh.error, nbytes - sizeof(oh), &cs);
+                fuse_copy_finish(&cs);
+                return err ? err : nbytes;
+        }
+
         err = -EINVAL;
-        if (!oh.unique || oh.error <= -1000 || oh.error > 0 ||
-            oh.len != nbytes)
+        if (oh.error <= -1000 || oh.error > 0)
                 goto err_finish;
 
         spin_lock(&fc->lock);
diff --git a/include/linux/fuse.h b/include/linux/fuse.h
index 608e300ae883..abde9949e2c0 100644
--- a/include/linux/fuse.h
+++ b/include/linux/fuse.h
@@ -203,6 +203,10 @@ enum fuse_opcode {
         FUSE_IOCTL         = 39,
 };
 
+enum fuse_notify_code {
+        FUSE_NOTIFY_CODE_MAX,
+};
+
 /* The read buffer is required to be at least 8k, but may be much larger */
 #define FUSE_MIN_READ_BUFFER 8192