Re: [PATCH 1/7] xfs: don't leak recovered attri intent items

["Darrick J. Wong" <djwong@kernel.org>]

On Wed, Nov 29, 2023 at 11:34:41PM -0800, Christoph Hellwig wrote:
> On Tue, Nov 28, 2023 at 12:26:34PM -0800, Darrick J. Wong wrote:
> > From: Darrick J. Wong <djwong@kernel.org>
> > 
> > If recovery finds an xattr log intent item calling for the removal of an
> > attribute and the file doesn't even have an attr fork, we know that the
> > removal is trivially complete.  However, we can't just exit the recovery
> > function without doing something about the recovered log intent item --
> > it's still on the AIL, and not logging an attrd item means it stays
> > there forever.
> > 
> > This has likely not been seen in practice because few people use LARP
> > and the runtime code won't log the attri for a no-attrfork removexattr
> > operation.  But let's fix this anyway.
> > 
> > Also we shouldn't really be testing the attr fork presence until we've
> > taken the ILOCK, though this doesn't matter much in recovery, which is
> > single threaded.
> > 
> > Fixes: fdaf1bb3cafc ("xfs: ATTR_REPLACE algorithm with LARP enabled needs rework")
> 
> No useful comment here as the attr logging code is new to me, but what
> is the LARP mode?  I see plenty of references to it in commit logs,
> a small amount in the code mostly related to error injection, but it
> would be really good to expand the acronym somehwere as I can't find
> any explanation in the code or commit logs..

LARP == Logged extended Attributes via Replay Persistence

(IOWs, a silly developer acronym for writing attr log intent items.)

--D