fuse: add reference counting to fuse_file

Make lifetime of 'struct fuse_file' independent from 'struct file' by adding a
reference counter and destructor.

This will enable asynchronous page writeback, where it cannot be guaranteed,
that the file is not released while a request with this file handle is being
served.

The actual RELEASE request is only sent when there are no more references to
the fuse_file.

Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 8 insertions, 5 deletions

diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
index 95bcb433d1b4..60683b787250 100644
--- a/fs/fuse/fuse_i.h
+++ b/fs/fuse/fuse_i.h
@@ -72,6 +72,9 @@ struct fuse_file {
 
         /** File handle used by userspace */
         u64 fh;
+
+        /** Refcount */
+        atomic_t count;
 };
 
 /** One input argument of a request */
@@ -216,7 +219,7 @@ struct fuse_req {
         unsigned page_offset;
 
         /** File used in the request (or NULL) */
-        struct file *file;
+        struct fuse_file *ff;
 
         /** vfsmount used in release */
         struct vfsmount *vfsmount;
@@ -420,7 +423,7 @@ void fuse_send_forget(struct fuse_conn *fc, struct fuse_req *req,
 /**
  * Initialize READ or READDIR request
  */
-void fuse_read_fill(struct fuse_req *req, struct file *file,
+void fuse_read_fill(struct fuse_req *req, struct fuse_file *ff,
                     struct inode *inode, loff_t pos, size_t count, int opcode);
 
 /**
@@ -433,9 +436,9 @@ 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);
 
-/** */
-struct fuse_req *fuse_release_fill(struct fuse_file *ff, u64 nodeid, int flags,
-                                   int opcode);
+/** Fill in ff->reserved_req with a RELEASE request */
+void fuse_release_fill(struct fuse_file *ff, u64 nodeid, int flags, int opcode);
+
 /**
  * Send RELEASE or RELEASEDIR request
  */