Re: [PATCH 11/19] xfs: refactor EFI log item recovery dispatch

From: "Darrick J. Wong" <darrick.wong@oracle.com>
To: Christoph Hellwig <hch@infradead.org>
Cc: linux-xfs@vger.kernel.org
Subject: Re: [PATCH 11/19] xfs: refactor EFI log item recovery dispatch
Date: Wed, 29 Apr 2020 07:20:56 -0700	[thread overview]
Message-ID: <20200429142056.GS6742@magnolia> (raw)
In-Reply-To: <20200429070916.GA2625@infradead.org>

On Wed, Apr 29, 2020 at 12:09:16AM -0700, Christoph Hellwig wrote:
> On Tue, Apr 28, 2020 at 04:45:57PM -0700, Darrick J. Wong wrote:
> > On Tue, Apr 28, 2020 at 03:41:32PM -0700, Darrick J. Wong wrote:
> > > On Sat, Apr 25, 2020 at 11:28:01AM -0700, Christoph Hellwig wrote:
> > > > On Tue, Apr 21, 2020 at 07:07:13PM -0700, Darrick J. Wong wrote:
> > > > > From: Darrick J. Wong <darrick.wong@oracle.com>
> > > > > 
> > > > > Move the extent free intent and intent-done log recovery code into the
> > > > > per-item source code files and use dispatch functions to call them.  We
> > > > > do these one at a time because there's a lot of code to move.  No
> > > > > functional changes.
> > > > 
> > > > What is the reason for splitting xlog_recover_item_type vs
> > > > xlog_recover_intent_type?  To me it would seem more logical to have
> > > > one operation vector, with some ops only set for intents.
> > > 
> > > Partly because I started by refactoring only the intent items, and then
> > > decided to prepend a series to do everything; and partly to be stingy
> > > with bytes. :P
> > > 
> > > That said, I like your suggestion of every XFS_LI_* code gets its own
> > > xlog_recover_item_type so I'll go do that.
> > 
> > Aha, now I remember why those two are separate types -- the
> > process_intent and cancel_intent functions operate on the xfs_log_item
> > that gets created from the xlog_recover_item that we pulled out of the
> > log, whereas the other functions are called directly on the
> > xlog_recovery_item.  There's no direct link between the log item and the
> > recovery log item, nor is there a good way to link through their
> > dispatch functions.
> 
> Maybe those should move to xfs_item_ops as they operate on a "live"
> xfs_log_item? (they'd need to grow names clearly related to recovery
> of course).  In fact except for slightly different calling convention
> ->cancel_intent already seems to be identical to ->abort_intent in
> xfs_item_ops, so that would be one off the list.

Hmm, yes, that's a better way out.  Trees, meet forest. ;)

> Btw, it seems like we should drop the ail_lock before calling
> ->process_intent as all instances do that anyway, and it would keep
> the locking a little more centralized, and it will allow killing
> one pointless wrapper in each instance.  Maybe we can also move
> the recovered flag to the generic log item flags?

Yeah, I was working on adding that to the patchset too.

--D