Re: [PATCH v23 13/22] vfs: Cache richacl in struct inode

Jeff Layton [off-list ref] wrote:

quoted

+	if (cmpxchg(&inode->i_acl, ACL_NOT_CACHED, sentinel) != ACL_NOT_CACHED)
+		/* fall through */ ;
+

So you do the same thing regardless of the outcome of the above? Why
bother with the if at all here? Just do the cmpxchg and toss out the
result.

gcc might complain if you don't check the result.

However, this does look like it's subject to a thundering herd problem.  If
30000 processes all look at the ACL at the same time on a network fs, could
that cause 30000 RPC calls to be transmitted for the same thing?

David