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.

3 files changed, 117 insertions, 45 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);
diff --git a/include/fuse_kernel.h b/include/fuse_kernel.h
index 92fa24c..c806a17 100644
--- a/include/fuse_kernel.h
+++ b/include/fuse_kernel.h
@@ -116,6 +116,9 @@
  *
  *  7.27
  *  - add FUSE_ABORT_ERROR
+ *
+ *  7.28
+ *  - add FUSE_COPY_FILE_RANGE
  */
 
 #ifndef _LINUX_FUSE_H
@@ -337,53 +340,54 @@ struct fuse_file_lock {
 #define FUSE_POLL_SCHEDULE_NOTIFY (1 << 0)
 
 enum fuse_opcode {
-	FUSE_LOOKUP	   = 1,
-	FUSE_FORGET	   = 2,  /* no reply */
-	FUSE_GETATTR	   = 3,
-	FUSE_SETATTR	   = 4,
-	FUSE_READLINK	   = 5,
-	FUSE_SYMLINK	   = 6,
-	FUSE_MKNOD	   = 8,
-	FUSE_MKDIR	   = 9,
-	FUSE_UNLINK	   = 10,
-	FUSE_RMDIR	   = 11,
-	FUSE_RENAME	   = 12,
-	FUSE_LINK	   = 13,
-	FUSE_OPEN	   = 14,
-	FUSE_READ	   = 15,
-	FUSE_WRITE	   = 16,
-	FUSE_STATFS	   = 17,
-	FUSE_RELEASE       = 18,
-	FUSE_FSYNC         = 20,
-	FUSE_SETXATTR      = 21,
-	FUSE_GETXATTR      = 22,
-	FUSE_LISTXATTR     = 23,
-	FUSE_REMOVEXATTR   = 24,
-	FUSE_FLUSH         = 25,
-	FUSE_INIT          = 26,
-	FUSE_OPENDIR       = 27,
-	FUSE_READDIR       = 28,
-	FUSE_RELEASEDIR    = 29,
-	FUSE_FSYNCDIR      = 30,
-	FUSE_GETLK         = 31,
-	FUSE_SETLK         = 32,
-	FUSE_SETLKW        = 33,
-	FUSE_ACCESS        = 34,
-	FUSE_CREATE        = 35,
-	FUSE_INTERRUPT     = 36,
-	FUSE_BMAP          = 37,
-	FUSE_DESTROY       = 38,
-	FUSE_IOCTL         = 39,
-	FUSE_POLL          = 40,
-	FUSE_NOTIFY_REPLY  = 41,
-	FUSE_BATCH_FORGET  = 42,
-	FUSE_FALLOCATE     = 43,
-	FUSE_READDIRPLUS   = 44,
-	FUSE_RENAME2       = 45,
-	FUSE_LSEEK         = 46,
+	FUSE_LOOKUP		= 1,
+	FUSE_FORGET		= 2,  /* no reply */
+	FUSE_GETATTR		= 3,
+	FUSE_SETATTR		= 4,
+	FUSE_READLINK		= 5,
+	FUSE_SYMLINK		= 6,
+	FUSE_MKNOD		= 8,
+	FUSE_MKDIR		= 9,
+	FUSE_UNLINK		= 10,
+	FUSE_RMDIR		= 11,
+	FUSE_RENAME		= 12,
+	FUSE_LINK		= 13,
+	FUSE_OPEN		= 14,
+	FUSE_READ		= 15,
+	FUSE_WRITE		= 16,
+	FUSE_STATFS		= 17,
+	FUSE_RELEASE		= 18,
+	FUSE_FSYNC		= 20,
+	FUSE_SETXATTR		= 21,
+	FUSE_GETXATTR		= 22,
+	FUSE_LISTXATTR		= 23,
+	FUSE_REMOVEXATTR	= 24,
+	FUSE_FLUSH		= 25,
+	FUSE_INIT		= 26,
+	FUSE_OPENDIR		= 27,
+	FUSE_READDIR		= 28,
+	FUSE_RELEASEDIR		= 29,
+	FUSE_FSYNCDIR		= 30,
+	FUSE_GETLK		= 31,
+	FUSE_SETLK		= 32,
+	FUSE_SETLKW		= 33,
+	FUSE_ACCESS		= 34,
+	FUSE_CREATE		= 35,
+	FUSE_INTERRUPT		= 36,
+	FUSE_BMAP		= 37,
+	FUSE_DESTROY		= 38,
+	FUSE_IOCTL		= 39,
+	FUSE_POLL		= 40,
+	FUSE_NOTIFY_REPLY	= 41,
+	FUSE_BATCH_FORGET	= 42,
+	FUSE_FALLOCATE		= 43,
+	FUSE_READDIRPLUS	= 44,
+	FUSE_RENAME2		= 45,
+	FUSE_LSEEK		= 46,
+	FUSE_COPY_FILE_RANGE	= 47,
 
 	/* CUSE specific operations */
-	CUSE_INIT          = 4096,
+	CUSE_INIT		= 4096,
 };
 
 enum fuse_notify_code {
@@ -792,4 +796,14 @@ struct fuse_lseek_out {
 	uint64_t	offset;
 };
 
+struct fuse_copy_file_range_in {
+	uint64_t	fh_in;
+	uint64_t	off_in;
+	uint64_t	nodeid_out;
+	uint64_t	fh_out;
+	uint64_t	off_out;
+	uint64_t	len;
+	uint64_t	flags;
+};
+
 #endif /* _LINUX_FUSE_H */
diff --git a/include/fuse_lowlevel.h b/include/fuse_lowlevel.h
index 395c0d9..12e3946 100644
--- a/include/fuse_lowlevel.h
+++ b/include/fuse_lowlevel.h
@@ -1160,6 +1160,42 @@ struct fuse_lowlevel_ops {
 	 */
 	void (*readdirplus) (fuse_req_t req, fuse_ino_t ino, size_t size, off_t off,
 			 struct fuse_file_info *fi);
+
+	/**
+	 * 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.
+	 *
+	 * If this request is answered with an error code of ENOSYS, this is
+	 * treated as a permanent failure with error code EOPNOTSUPP, i.e. all
+	 * future copy_file_range() requests will fail with EOPNOTSUPP without
+	 * being send to the filesystem process.
+	 *
+	 * Valid replies:
+	 *   fuse_reply_write
+	 *   fuse_reply_err
+	 *
+	 * @param req request handle
+	 * @param ino_in the inode number or the source file
+	 * @param off_in starting point from were the data should be read
+	 * @param fi_in file information of the source file
+	 * @param ino_out the inode number or the destination file
+	 * @param off_out starting point where the data should be written
+	 * @param fi_out file information of the destination file
+	 * @param len maximum size of the data to copy
+	 * @param flags passed along with the copy_file_range() syscall
+	 */
+	void (*copy_file_range) (fuse_req_t req, fuse_ino_t ino_in,
+				 off_t off_in, struct fuse_file_info *fi_in,
+				 fuse_ino_t ino_out, off_t off_out,
+				 struct fuse_file_info *fi_out, size_t len,
+				 int flags);
 };
 
 /**