From: "Darrick J. Wong" <djwong@kernel.org>
To: Christoph Hellwig <hch@lst.de>
Cc: Matthew Wilcox <willy@infradead.org>,
David Howells <dhowells@redhat.com>,
trond.myklebust@primarydata.com, darrick.wong@oracle.com,
jlayton@kernel.org, sfrench@samba.org,
torvalds@linux-foundation.org, linux-nfs@vger.kernel.org,
linux-mm@kvack.org, linux-fsdevel@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2/2] mm: Make swap_readpage() for SWP_FS_OPS use ->direct_IO() not ->readpage()
Date: Thu, 12 Aug 2021 10:48:18 -0700 [thread overview]
Message-ID: <20210812174818.GK3601405@magnolia> (raw)
In-Reply-To: <20210812170233.GA4987@lst.de>
On Thu, Aug 12, 2021 at 07:02:33PM +0200, Christoph Hellwig wrote:
> On Thu, Aug 12, 2021 at 04:39:40PM +0100, Matthew Wilcox wrote:
> > I agree with David; we want something lower-level for swap to call into.
> > I'd suggest aops->swap_rw and an implementation might well look
> > something like:
> >
> > static ssize_t ext4_swap_rw(struct kiocb *iocb, struct iov_iter *iter)
> > {
> > return iomap_dio_rw(iocb, iter, &ext4_iomap_ops, NULL, 0);
> > }
>
> Yes, that might make sense and would also replace the awkward IOCB_SWAP
> flag for the write side.
>
> For file systems like ext4 and xfs that have an in-memory block mapping
> tree this would be way better than the current version and also support
> swap on say multi-device file systems properly. We'd just need to be
> careful to read the extent information in at extent_activate time,
> by doing xfs_iread_extents for XFS or the equivalents in other file
> systems.
You'd still want to walk the extent map at activation time to reject
swapfiles with holes, shared extents, etc., right?
--D
next prev parent reply other threads:[~2021-08-12 17:48 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-08-12 11:57 [PATCH 0/2] mm: Fix NFS swapfiles and use DIO read for swapfiles David Howells
2021-08-12 11:57 ` [PATCH 1/2] nfs: Fix write to swapfile failure due to generic_write_checks() David Howells
2021-08-12 11:57 ` [PATCH 2/2] mm: Make swap_readpage() for SWP_FS_OPS use ->direct_IO() not ->readpage() David Howells
2021-08-12 12:21 ` Christoph Hellwig
2021-08-12 12:57 ` David Howells
2021-08-12 15:39 ` Matthew Wilcox
2021-08-12 17:02 ` Christoph Hellwig
2021-08-12 17:48 ` Darrick J. Wong [this message]
2021-08-12 18:14 ` Matthew Wilcox
2021-08-12 20:13 ` Theodore Ts'o
2021-08-13 6:54 ` Christoph Hellwig
2021-08-12 13:00 ` Matthew Wilcox
2021-08-12 13:23 ` David Howells
2021-08-12 13:37 ` David Howells
2021-08-12 13:50 ` Matthew Wilcox
2021-08-12 14:16 ` David Howells
2021-08-12 12:18 ` [PATCH 0/2] mm: Fix NFS swapfiles and use DIO read for swapfiles Christoph Hellwig
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