On Fri, Apr 26, 2024 at 11:20:36AM -0300, Fabiano Rosas wrote:
> When doing file migration, QEMU accepts an offset that should be
> skipped when writing the migration stream to the file. The purpose of
> the offset is to allow the management layer to put its own metadata at
> the start of the file.
>
> We have tests for this in migration-test, but only testing that the
> migration stream starts at the correct offset and not that it actually
> leaves the data intact. Unsurprisingly, there's been a bug in that
> area that the tests didn't catch.
>
> Fix the tests to write some data to the offset region and check that
> it's actually there after the migration.
>
> Fixes: 3dc35470c8 ("tests/qtest: migration-test: Add tests for file-based
> migration")
> Signed-off-by: Fabiano Rosas <[email protected]>
> ---
> tests/qtest/migration-test.c | 70 +++++++++++++++++++++++++++++++++---
> 1 file changed, 65 insertions(+), 5 deletions(-)
>
> diff --git a/tests/qtest/migration-test.c b/tests/qtest/migration-test.c
> index 5d6d8cd634..7b177686b4 100644
> --- a/tests/qtest/migration-test.c
> +++ b/tests/qtest/migration-test.c
> @@ -2081,6 +2081,63 @@ static void test_precopy_file(void)
> test_file_common(&args, true);
> }
>
> +#ifndef _WIN32
> +static void file_dirty_offset_region(void)
> +{
> +#if defined(__linux__)
Hmm, what's the case to cover when !_WIN32 && __linux__? Can we remove one
layer of ifdef?
I'm also wondering why it can't work on win32? I thought win32 has all
these stuff we used here, but I may miss something.
> + g_autofree char *path = g_strdup_printf("%s/%s", tmpfs,
> FILE_TEST_FILENAME);
> + size_t size = FILE_TEST_OFFSET;
> + uintptr_t *addr, *p;
> + int fd;
> +
> + fd = open(path, O_CREAT | O_RDWR, 0660);
> + g_assert(fd != -1);
> +
> + g_assert(!ftruncate(fd, size));
> +
> + addr = mmap(NULL, size, PROT_WRITE, MAP_SHARED, fd, 0);
> + g_assert(addr != MAP_FAILED);
> +
> + /* ensure the skipped offset contains some data */
> + p = addr;
> + while (p < addr + FILE_TEST_OFFSET / sizeof(uintptr_t)) {
> + *p = (unsigned long) FILE_TEST_FILENAME;
This is fine, but not as clear what is assigned.. I think here we assigned
is the pointer pointing to the binary's RO section (rather than the chars).
Maybe using some random numbers would be more straightforward, but no
strong opinions.
> + p++;
> + }
> +
> + munmap(addr, size);
> + fsync(fd);
> + close(fd);
> +#endif
> +}
> +
> +static void *file_offset_start_hook(QTestState *from, QTestState *to)
> +{
> + g_autofree char *file = g_strdup_printf("%s/%s", tmpfs,
> FILE_TEST_FILENAME);
> + int src_flags = O_WRONLY;
> + int dst_flags = O_RDONLY;
> + int fds[2];
> +
> + file_dirty_offset_region();
> +
> + fds[0] = open(file, src_flags, 0660);
> + assert(fds[0] != -1);
> +
> + fds[1] = open(file, dst_flags, 0660);
> + assert(fds[1] != -1);
> +
> + qtest_qmp_fds_assert_success(from, &fds[0], 1, "{'execute': 'add-fd', "
> + "'arguments': {'fdset-id': 1}}");
> +
> + qtest_qmp_fds_assert_success(to, &fds[1], 1, "{'execute': 'add-fd', "
> + "'arguments': {'fdset-id': 1}}");
> +
> + close(fds[0]);
> + close(fds[1]);
> +
> + return NULL;
> +}
> +
> static void file_offset_finish_hook(QTestState *from, QTestState *to,
> void *opaque)
> {
> @@ -2096,12 +2153,12 @@ static void file_offset_finish_hook(QTestState *from,
> QTestState *to,
> g_assert(addr != MAP_FAILED);
>
> /*
> - * Ensure the skipped offset contains zeros and the migration
> - * stream starts at the right place.
> + * Ensure the skipped offset region's data has not been touched
> + * and the migration stream starts at the right place.
> */
> p = addr;
> while (p < addr + FILE_TEST_OFFSET / sizeof(uintptr_t)) {
> - g_assert(*p == 0);
> + g_assert_cmpstr((char *) *p, ==, FILE_TEST_FILENAME);
> p++;
> }
> g_assert_cmpint(cpu_to_be64(*p) >> 32, ==, QEMU_VM_FILE_MAGIC);
> @@ -2113,17 +2170,18 @@ static void file_offset_finish_hook(QTestState *from,
> QTestState *to,
>
> static void test_precopy_file_offset(void)
> {
> - g_autofree char *uri = g_strdup_printf("file:%s/%s,offset=%d", tmpfs,
> - FILE_TEST_FILENAME,
> + g_autofree char *uri = g_strdup_printf("file:/dev/fdset/1,offset=%d",
> FILE_TEST_OFFSET);
Do we want to keep both tests to cover both normal file and fdsets?
> MigrateCommon args = {
> .connect_uri = uri,
> .listen_uri = "defer",
> + .start_hook = file_offset_start_hook,
> .finish_hook = file_offset_finish_hook,
> };
>
> test_file_common(&args, false);
> }
> +#endif
>
> static void test_precopy_file_offset_bad(void)
> {
> @@ -3636,8 +3694,10 @@ int main(int argc, char **argv)
>
> migration_test_add("/migration/precopy/file",
> test_precopy_file);
> +#ifndef _WIN32
> migration_test_add("/migration/precopy/file/offset",
> test_precopy_file_offset);
> +#endif
> migration_test_add("/migration/precopy/file/offset/bad",
> test_precopy_file_offset_bad);
>
> --
> 2.35.3
>
--
Peter Xu
