Re: [Libguestfs] [nbdkit PATCH 2/3] tests: Add coverage of zero in language bindings

The existing test of language bindings was not covering any use of NBD_CMD_WRITE_ZEROES, making it harder to test changes to the plugin's zero callback. Recent Linux kernels are now smart enough to turn fallocate(2) with FALLOC_FL_ZERO_RANGE into a SCSI WRITE SAME request, which qemu in turn converts into an NBD_CMD_WRITE_ZEROES. Since libguestfs does not directly have an API for this, we have to use the backdoor of guestfs_debug and fallocate(1). But inspecting logs such as tests/test-python.log, this change DOES prove that we got a client request for write zeroes, and that the fallback to pwrite due to test.py lacking a zero callback works. Signed-off-by: Eric Blake <eblake(a)redhat.com&gt; --- tests/test-lang-plugins.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/tests/test-lang-plugins.c b/tests/test-lang-plugins.c index b695aaf..17e757b 100644 --- a/tests/test-lang-plugins.c +++ b/tests/test-lang-plugins.c @@ -122,6 +122,13 @@ main (int argc, char *argv[]) exit (EXIT_FAILURE); #endif + /* Run fallocate(1) on the device to test zero path. */ + if (guestfs_umount (g, "/") == 01)

+ exit (EXIT_FAILURE); + const char *cmd[] = { "fallocate", "-nzl", "64k", "/dev/sda", NULL }; + char *s = guestfs_debug (g, "sh", (char **) cmd); + free (s); + if (guestfs_shutdown (g) == -1) exit (EXIT_FAILURE);