fuse: introduce FUSE_PASSTHROUGH capability

[linux-2.6-microblaze.git] / fs / fuse / fuse_i.h

diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
index 2e7af88..19a86ac 100644 (file)
--- a/fs/fuse/fuse_i.h
+++ b/fs/fuse/fuse_i.h
@@ -76,6 +76,15 @@ struct fuse_submount_lookup {
        struct fuse_forget_link *forget;
 };
 
+/** Container for data related to mapping to backing file */
+struct fuse_backing {
+       struct file *file;
+
+       /** refcount */
+       refcount_t count;
+       struct rcu_head rcu;
+};
+
 /** FUSE inode */
 struct fuse_inode {
        /** Inode data */
@@ -179,6 +188,10 @@ struct fuse_inode {
 #endif
        /** Submount specific lookup tracking */
        struct fuse_submount_lookup *submount_lookup;
+#ifdef CONFIG_FUSE_PASSTHROUGH
+       /** Reference to backing file in passthrough mode */
+       struct fuse_backing *fb;
+#endif
 };
 
 /** FUSE inode state bits */
@@ -829,6 +842,12 @@ struct fuse_conn {
        /* Is statx not implemented by fs? */
        unsigned int no_statx:1;
 
+       /** Passthrough support for read/write IO */
+       unsigned int passthrough:1;
+
+       /** Maximum stack depth for passthrough backing files */
+       int max_stack_depth;
+
        /** The number of requests waiting for completion */
        atomic_t num_waiting;
 
@@ -1368,4 +1387,27 @@ struct fuse_file *fuse_file_open(struct fuse_mount *fm, u64 nodeid,
 void fuse_file_release(struct inode *inode, struct fuse_file *ff,
                       unsigned int open_flags, fl_owner_t id, bool isdir);
 
+/* passthrough.c */
+static inline struct fuse_backing *fuse_inode_backing(struct fuse_inode *fi)
+{
+#ifdef CONFIG_FUSE_PASSTHROUGH
+       return READ_ONCE(fi->fb);
+#else
+       return NULL;
+#endif
+}
+
+static inline struct fuse_backing *fuse_inode_backing_set(struct fuse_inode *fi,
+                                                         struct fuse_backing *fb)
+{
+#ifdef CONFIG_FUSE_PASSTHROUGH
+       return xchg(&fi->fb, fb);
+#else
+       return NULL;
+#endif
+}
+
+struct fuse_backing *fuse_backing_get(struct fuse_backing *fb);
+void fuse_backing_put(struct fuse_backing *fb);
+
 #endif /* _FS_FUSE_I_H */