From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrew Morton Date: Fri, 15 Apr 2011 08:10:54 -0700 Subject: [Ocfs2-devel] [PATCH V8 4/8] mm/fs: add hooks to support cleancache In-Reply-To: <83ef8b69-f041-43e6-a5a9-880ff3da26f2@default> References: <20110414211732.GA27761@ca-server1.us.oracle.com BANLkTimEbtY8F6bpsfhfQ770ao9Hn7Spww@mail.gmail.com> <83ef8b69-f041-43e6-a5a9-880ff3da26f2@default> Message-ID: <20110415081054.79a164d3.akpm@linux-foundation.org> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Dan Magenheimer Cc: Minchan Kim , Chris Mason , viro@zeniv.linux.org.uk, adilger.kernel@dilger.ca, tytso@mit.edu, mfasheh@suse.com, jlbec@evilplan.org, matthew@wil.cx, linux-btrfs@vger.kernel.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org, ocfs2-devel@oss.oracle.com, linux-mm@kvack.org, hch@infradead.org, ngupta@vflare.org, jeremy@goop.org, JBeulich@novell.com, Kurt Hackel , npiggin@kernel.dk, Dave Mccracken , riel@redhat.com, avi@redhat.com, Konrad Wilk , mel@csn.ul.ie, yinghan@google.com, gthelen@google.com, torvalds@linux-foundation.org On Fri, 15 Apr 2011 07:47:57 -0700 (PDT) Dan Magenheimer wrote: > Hi Minchan -- > > > First of all, thanks for resolving conflict with my patch. > > You're welcome! As I pointed out offlist, yours was the first > change in MM that caused any semantic changes to the cleancache > core hooks patch since before 2.6.18. > > > Before I suggested a thing about cleancache_flush_page, > > cleancache_flush_inode. > > > > what's the meaning of flush's semantic? > > I thought it means invalidation. > > AFAIC, how about change flush with invalidate? > > I'm not sure the words "flush" and "invalidate" are defined > precisely or used consistently everywhere in computer > science, but I think that "invalidate" is to destroy > a "pointer" to some data, but not necessarily destroy the > data itself. And "flush" means to actually remove > the data. So one would "invalidate a mapping" but one > would "flush a cache". > > Since cleancache_flush_page and cleancache_flush_inode > semantically remove data from cleancache, I think flush > is a better name than invalidate. > > Does that make sense? > nope ;) Kernel code freely uses "flush" to refer to both invalidation and to writeback, sometimes in confusing ways. In this case, cleancache_flush_inode and cleancache_flush_page rather sound like they might write those things to backing store.