linux-ext4 - Re: [RFC PATCH v2 08/19] fs/xfs: Fail truncate if page lease can't be broken

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Date:   Sat, 10 Aug 2019 09:22:09 +1000
From:   Dave Chinner <david@...morbit.com>
To:     ira.weiny@...el.com
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        Jason Gunthorpe <jgg@...pe.ca>,
        Dan Williams <dan.j.williams@...el.com>,
        Matthew Wilcox <willy@...radead.org>, Jan Kara <jack@...e.cz>,
        Theodore Ts'o <tytso@....edu>,
        John Hubbard <jhubbard@...dia.com>,
        Michal Hocko <mhocko@...e.com>, linux-xfs@...r.kernel.org,
        linux-rdma@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-fsdevel@...r.kernel.org, linux-nvdimm@...ts.01.org,
        linux-ext4@...r.kernel.org, linux-mm@...ck.org
Subject: Re: [RFC PATCH v2 08/19] fs/xfs: Fail truncate if page lease can't
 be broken

On Fri, Aug 09, 2019 at 03:58:22PM -0700, ira.weiny@...el.com wrote:
> From: Ira Weiny <ira.weiny@...el.com>
> 
> If pages are under a lease fail the truncate operation.  We change the order of
> lease breaks to directly fail the operation if the lease exists.
> 
> Select EXPORT_BLOCK_OPS for FS_DAX to ensure that xfs_break_lease_layouts() is
> defined for FS_DAX as well as pNFS.
> 
> Signed-off-by: Ira Weiny <ira.weiny@...el.com>
> ---
>  fs/Kconfig        | 1 +
>  fs/xfs/xfs_file.c | 5 +++--
>  2 files changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/fs/Kconfig b/fs/Kconfig
> index 14cd4abdc143..c10b91f92528 100644
> --- a/fs/Kconfig
> +++ b/fs/Kconfig
> @@ -48,6 +48,7 @@ config FS_DAX
>  	select DEV_PAGEMAP_OPS if (ZONE_DEVICE && !FS_DAX_LIMITED)
>  	select FS_IOMAP
>  	select DAX
> +	select EXPORTFS_BLOCK_OPS
>  	help
>  	  Direct Access (DAX) can be used on memory-backed block devices.
>  	  If the block device supports DAX and the filesystem supports DAX,

That looks wrong. If you require xfs_break_lease_layouts() outside
of pnfs context, then move the function in the XFS code base to a
file that is built in. It's only external dependency is on the
break_layout() function, and XFS already has other unconditional
direct calls to break_layout()...

Cheers,

Dave.
-- 
Dave Chinner
david@...morbit.com