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Date: Wed, 27 Mar 2024 11:06:00 -0700
From: "Darrick J. Wong" <djwong@kernel.org>
To: Christoph Hellwig <hch@lst.de>
Cc: Chandan Babu R <chandan.babu@oracle.com>,
	Dave Chinner <david@fromorbit.com>, linux-xfs@vger.kernel.org
Subject: Re: [PATCH 04/13] xfs: move RT inode locking out of __xfs_bunmapi
Message-ID: <20240327180600.GC6390@frogsfrogsfrogs>
References: <20240327110318.2776850-1-hch@lst.de>
 <20240327110318.2776850-5-hch@lst.de>
 <20240327150755.GX6390@frogsfrogsfrogs>
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In-Reply-To: <20240327170632.GC32019@lst.de>

On Wed, Mar 27, 2024 at 06:06:32PM +0100, Christoph Hellwig wrote:
> On Wed, Mar 27, 2024 at 08:07:55AM -0700, Darrick J. Wong wrote:
> > How does it happen that xfs_rtfree_blocks gets called more than once in
> > the same transaction?  Is that simply the effect of xfs_bunmapi_range
> > and xfs_unmap_exten calling __xfs_bunmapi with
> > nextents == XFS_ITRUNC_MAX_EXTENTS==2?
> 
> Yes.
> 
> > What if we simply didn't unmap multiple extents per bunmapi call for
> > realtime files?  Would that eliminate the need for
> > XFS_TRANS_RTBITMAP_LOCKED?
> 
> Probably.  Not that I really want to rock that boat now when we'll
> also have the extent free item / defer ops based path soon.

<nod> I think once we get to the rtgroups patchset then all we have to
do in __xfs_bunmapi is:

	if (XFS_IS_REALTIME_INODE(ip) && whichfork == XFS_DATA_FORK &&
	    !xfs_has_rtgroups(mp))
		nexts = 1;

and then the XFS_TRANS_RTBITMAP_LOCKED flag can go away?

If so, then
Reviewed-by: Darrick J. Wong <djwong@kernel.org>

--D