From: "J. Bruce Fields" <bfields@xxxxxxxxxx> We have a report of failed upcalls that occur when use_ipaddr is toggled. The problem appears to be that for example after turning on use_ipaddr, the kernel may still see upcalls for clients such as "*". The following patches (untested except to check that they compile...) attempt to fix that by just letting nfsd_fh() accept either client type; does anyone see a problem with that? The current code actually attempts to avoid tihs problem by flushing caches on a use_ipaddr change (see the cache_flush() call in utils/mountd/auth.c:check_useipaddr(). But that doesn't work, because a write to a cache/flush file doesn't actually provide useful guarantees to the caller on return: - as far as I can tell, cache_clean leaves alone any entries that were created in the current second. - cache_clean only removes entries from the cache, it doesn't wait for them to actually be destroyed: so an in-progress nfsd thread could still make an upcall using information from one of the flushed entries. These seem like bugs in their own right to me: a cache-flush operation that actually guaranteed the entries were gone on return would be more useful. And I wonder whether this doesn't also cause exportfs bugs.... I'm not sure what to do about it, though. I don't think the existing interface is really fixable, since fixing the second problem above would (I think) require the cache/flush write to wait on in-progress rpc's, but those in-progress rpc's could be waiting on mountd, creating a deadlock. A new interface shouldn't need to accept a time--every actual user just wants to cache flushed now. Maybe the first problem could be solved by replacing the time by a counter incremented on each insert of a cache entry. And the second could be fixed by waiting on in-progress rpc's. That might not help mountd, but it would help exportfs at least. --b. J. Bruce Fields (3): mountd: unconditionally resolve ip address mountd: helper function for export upcall's client matching mountd: ignore use_ipaddr and just try both client types utils/mountd/cache.c | 38 +++++++++++++++++++++++++------------- 1 files changed, 25 insertions(+), 13 deletions(-) -- 1.7.7.6 -- To unsubscribe from this list: send the line "unsubscribe linux-nfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
