libparted: avoid race in informing the kernel of partition table changes

When sync'ing a partition table change using the latest
code, sometimes we'd get an unwarranted failure like this:

    Warning: Partition(s) 1 on /dev/sdd have been written, but we
    have been unable to inform the kernel of the change, probably because
    it/they are in use.  As a result, the old partition(s) will remain in
    use.  You should reboot now before making further changes.

To be precise, when running the partition-resizing root-only test
in a loop:

    for i in $(seq 240); do make -C tests check VERBOSE=yes \
    TESTS=t3000-resize-fs.sh >& log.$i && printf . || echo $i $?; done

I would typically see about 50% of them fail on a Fedora 13 system.
It was obvious that this was due to a race condition when I found that
modifying that tests' parted...resize invocation to go via strace changed
the timing enough to make the test pass every time.

The fix is to retry the partition-removal step upon any EBUSY failure,
currently for up to 1 second (retrying up to 100 times, sleeping 10ms
after each failure).

* libparted/arch/linux.c (_disk_sync_part_table): Allocate "ok" using
calloc, now that its initial values matter.
Retry each removal upon EBUSY-failure.
* bootstrap.conf (gnulib_modules): Use gnulib's usleep module.

1 files changed, 1 insertions, 0 deletions

diff --git a/bootstrap.conf b/bootstrap.conf
index 6c9287d..4ca51a7 100644
--- a/bootstrap.conf
+++ b/bootstrap.conf
@@ -58,6 +58,7 @@ gnulib_modules="
 	unlink
 	update-copyright
 	useless-if-before-free
+	usleep
 	vc-list-files
 	version-etc-fsf
 	warnings