fuse: add file kernel handle

The file handle, fuse_file->fh, is opaque value supplied by userland
FUSE server and uniqueness is not guaranteed.  Add file kernel handle,
fuse_file->kh, which is allocated by the kernel on file allocation and
guaranteed to be unique.

This will be used by poll to match notification to the respective file
but can be used for other purposes where unique file handle is
necessary.

Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>

1 files changed, 7 insertions, 1 deletions

diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
index 4fc5131f5c9d..86f013303828 100644
--- a/fs/fuse/fuse_i.h
+++ b/fs/fuse/fuse_i.h
@@ -100,6 +100,9 @@ struct fuse_file {
         /** Request reserved for flush and release */
         struct fuse_req *reserved_req;
 
+        /** Kernel file handle guaranteed to be unique */
+        u64 kh;
+
         /** File handle used by userspace */
         u64 fh;
 
@@ -322,6 +325,9 @@ struct fuse_conn {
         /** The list of requests under I/O */
         struct list_head io;
 
+        /** The next unique kernel file handle */
+        u64 khctr;
+
         /** Number of requests currently in the background */
         unsigned num_background;
 
@@ -499,7 +505,7 @@ void fuse_read_fill(struct fuse_req *req, struct file *file,
  */
 int fuse_open_common(struct inode *inode, struct file *file, int isdir);
 
-struct fuse_file *fuse_file_alloc(void);
+struct fuse_file *fuse_file_alloc(struct fuse_conn *fc);
 void fuse_file_free(struct fuse_file *ff);
 void fuse_finish_open(struct inode *inode, struct file *file,
                       struct fuse_file *ff, struct fuse_open_out *outarg);