example/passthrough: support fspacectl()

FreeBSD 14 introduced a new system call, fspacectl().
Currently, it supports one operation mode, SPACECTL_DEALLOC,
which is functionally equivalent to Linux fallocate() with
FALLOC_FL_KEEP_SIZE|FALLOC_FL_PUNCH_HOLE flags.

fspacectl() calls with SPACECTL_DEALLOC is supported on FUSE
filesystems via FUSE_FALLOCATE with the aforementioned flags.

Signed-off-by: CismonX <admin@cismon.net>

example/passthrough_helpers.h

@@ -50,6 +50,19 @@ static inline int do_fallocate(int fd, int mode, off_t offset, off_t length)
 		return -posix_fallocate(fd, offset, length);
 #endif
 
+#ifdef HAVE_FSPACECTL
+	// 0x3 == FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE
+	if (mode == 0x3) {
+		struct spacectl_range sr;
+
+		sr.r_offset = offset;
+		sr.r_len = length;
+		if (fspacectl(fd, SPACECTL_DEALLOC, &sr, 0, NULL) == -1)
+			return -errno;
+		return 0;
+	}
+#endif
+
 	return -EOPNOTSUPP;
 #endif  // HAVE_FALLOCATE
 }

meson.build

@@ -74,7 +74,7 @@ private_cfg.set_quoted('PACKAGE_VERSION', meson.project_version())
 # Test for presence of some functions
 test_funcs = [ 'fork', 'fstatat', 'openat', 'readlinkat', 'pipe2',
                'splice', 'vmsplice', 'posix_fallocate', 'fdatasync',
-               'utimensat', 'copy_file_range', 'fallocate' ]
+               'utimensat', 'copy_file_range', 'fallocate', 'fspacectl' ]
 foreach func : test_funcs
     private_cfg.set('HAVE_' + func.to_upper(),
         cc.has_function(func, prefix: include_default, args: args_default))