libfuse: add copy_file_range() support

Add support for the relatively new copy_file_range() syscall. Backend
filesystems can now implement an efficient way of cloning/duplicating
data ranges within files. See 'man 2 copy_file_range' for more details.

1 files changed, 22 insertions, 0 deletions

diff --git a/include/fuse.h b/include/fuse.h
index 24e04bc..d3644ad 100644
--- a/include/fuse.h
+++ b/include/fuse.h
@@ -750,6 +750,23 @@ struct fuse_operations {
 	 */
 	int (*fallocate) (const char *, int, off_t, off_t,
 			  struct fuse_file_info *);
+
+	/**
+	 * Copy a range of data from one file to another
+	 *
+	 * Performs an optimized copy between two file descriptors without the
+	 * additional cost of transferring data through the FUSE kernel module
+	 * to user space (glibc) and then back into the FUSE filesystem again.
+	 *
+	 * In case this method is not implemented, glibc falls back to reading
+	 * data from the source and writing to the destination. Effectively
+	 * doing an inefficient copy of the data.
+	 */
+	ssize_t (*copy_file_range) (const char *path_in,
+				    struct fuse_file_info *fi_in,
+				    off_t offset_in, const char *path_out,
+				    struct fuse_file_info *fi_out,
+				    off_t offset_out, size_t size, int flags);
 };
 
 /** Extra context that may be needed by some filesystems
@@ -1165,6 +1182,11 @@ int fuse_fs_poll(struct fuse_fs *fs, const char *path,
 		 unsigned *reventsp);
 int fuse_fs_fallocate(struct fuse_fs *fs, const char *path, int mode,
 		 off_t offset, off_t length, struct fuse_file_info *fi);
+ssize_t fuse_fs_copy_file_range(struct fuse_fs *fs, const char *path_in,
+				struct fuse_file_info *fi_in, off_t off_in,
+				const char *path_out,
+				struct fuse_file_info *fi_out, off_t off_out,
+				size_t len, int flags);
 void fuse_fs_init(struct fuse_fs *fs, struct fuse_conn_info *conn,
 		struct fuse_config *cfg);
 void fuse_fs_destroy(struct fuse_fs *fs);