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From: David Howells <dhowells@redhat.com>
To: Christoph Hellwig <hch@lst.de>,
	"Matthew Wilcox (Oracle)" <willy@infradead.org>
Cc: dhowells@redhat.com, Trond Myklebust <trondmy@hammerspace.com>,
	Anna Schumaker <anna.schumaker@netapp.com>,
	Steve French <sfrench@samba.org>,
	Dominique Martinet <asmadeus@codewreck.org>,
	Alexander Viro <viro@zeniv.linux.org.uk>,
	linux-mm@kvack.org, linux-cachefs@redhat.com,
	linux-afs@lists.infradead.org, linux-nfs@vger.kernel.org,
	linux-cifs@vger.kernel.org, ceph-devel@vger.kernel.org,
	v9fs-developer@lists.sourceforge.net,
	linux-fsdevel@vger.kernel.org, Jeff Layton <jlayton@redhat.com>,
	David Wysochanski <dwysocha@redhat.com>,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH 03/33] mm: Implement readahead_control pageset expansion
Date: Tue, 16 Feb 2021 11:48:24 +0000	[thread overview]
Message-ID: <1429175.1613476104@warthog.procyon.org.uk> (raw)
In-Reply-To: <20210216103215.GB27714@lst.de>

Christoph Hellwig <hch@lst.de> wrote:

> On Mon, Feb 15, 2021 at 03:44:52PM +0000, David Howells wrote:
> > Provide a function, readahead_expand(), that expands the set of pages
> > specified by a readahead_control object to encompass a revised area with a
> > proposed size and length.
> ...
> So looking at linux-next this seems to have a user, but that user is
> dead wood given that nothing implements ->expand_readahead.

Interesting question.  Code on my fscache-iter branch does implement this, but
I was asked to split the patchset up, so that's not in this subset.

> Looking at the code structure I think netfs_readahead and
> netfs_rreq_expand is a complete mess and needs to be turned upside
> down, that is instead of calling back from netfs_readahead to the
> calling file system, split it into a few helpers called by the
> caller.
> 
> But even after this can't we just expose the cache granule boundary
> to the VM so that the read-ahead request gets setup correctly from
> the very beginning?

You need to argue this one with Willy.  In my opinion, the VM should ask the
filesystem and the expansion be done before ->readahead() is called.  Willy
disagrees, however.

David



  parent reply	other threads:[~2021-02-16 11:48 UTC|newest]

Thread overview: 47+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-02-15 15:44 [PATCH 00/33] Network fs helper library & fscache kiocb API [ver #3] David Howells
2021-02-15 15:44 ` [PATCH 01/33] iov_iter: Add ITER_XARRAY David Howells
2021-02-15 15:44 ` [PATCH 02/33] mm: Add an unlock function for PG_private_2/PG_fscache David Howells
2021-02-16 10:26   ` Christoph Hellwig
2021-02-15 15:44 ` [PATCH 03/33] mm: Implement readahead_control pageset expansion David Howells
2021-02-16 10:32   ` Christoph Hellwig
2021-02-16 13:22     ` Matthew Wilcox
2021-02-17 14:36       ` Mike Marshall
2021-02-17 15:42       ` David Howells
2021-02-17 16:59         ` Mike Marshall
2021-02-17 22:20         ` David Howells
2021-02-16 11:48   ` David Howells [this message]
2021-02-17 16:13   ` Matthew Wilcox
2021-02-17 22:34   ` David Howells
2021-02-17 22:49     ` Matthew Wilcox
2021-02-18 17:47   ` David Howells
2021-02-15 15:45 ` [PATCH 04/33] vfs: Export rw_verify_area() for use by cachefiles David Howells
2021-02-16 10:26   ` Christoph Hellwig
2021-02-16 11:55   ` David Howells
2021-02-15 15:45 ` [PATCH 05/33] netfs: Make a netfs helper module David Howells
2021-02-15 15:45 ` [PATCH 06/33] netfs, mm: Move PG_fscache helper funcs to linux/netfs.h David Howells
2021-02-15 15:45 ` [PATCH 07/33] netfs, mm: Add unlock_page_fscache() and wait_on_page_fscache() David Howells
2021-02-15 15:45 ` [PATCH 08/33] netfs: Provide readahead and readpage netfs helpers David Howells
2021-02-15 15:45 ` [PATCH 09/33] netfs: Add tracepoints David Howells
2021-02-15 15:46 ` [PATCH 10/33] netfs: Gather stats David Howells
2021-02-15 15:46 ` [PATCH 11/33] netfs: Add write_begin helper David Howells
2021-02-15 15:46 ` [PATCH 12/33] netfs: Define an interface to talk to a cache David Howells
2021-02-15 15:46 ` [PATCH 13/33] netfs: Hold a ref on a page when PG_private_2 is set David Howells
2021-02-15 18:05 ` [PATCH 00/33] Network fs helper library & fscache kiocb API [ver #3] Jeff Layton
2021-02-16  0:40   ` Steve French
2021-02-16  2:10     ` Matthew Wilcox
2021-02-16  5:18       ` Steve French
2021-02-16  5:22       ` Steve French
2021-02-23 20:27         ` Matthew Wilcox
2021-02-24  4:57           ` Steve French
2021-02-24 13:32       ` David Howells
2021-02-24 15:51         ` Matthew Wilcox
2021-02-16 11:01     ` Jeff Layton
2021-02-15 22:46 ` [PATCH 34/33] netfs: Use in_interrupt() not in_softirq() David Howells
2021-02-16  8:42   ` Christoph Hellwig
2021-02-16  9:06     ` Sebastian Andrzej Siewior
2021-02-16  9:29   ` David Howells
2021-02-16  9:30     ` Christoph Hellwig
2021-02-18 14:02     ` [PATCH 34/33] netfs: Pass flag rather than use in_softirq() David Howells
2021-02-18 15:06       ` Marc Dionne
2021-02-18 15:16       ` Marc Dionne
2021-02-19  9:01       ` Sebastian Andrzej Siewior

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