[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Date: Fri, 21 Apr 2023 02:11:45 +0100
From: Al Viro <viro@...iv.linux.org.uk>
To: David Howells <dhowells@...hat.com>
Cc: Jens Axboe <axboe@...nel.dk>,
Christoph Hellwig <hch@...radead.org>,
Matthew Wilcox <willy@...radead.org>, Jan Kara <jack@...e.cz>,
Jeff Layton <jlayton@...nel.org>,
David Hildenbrand <david@...hat.com>,
Jason Gunthorpe <jgg@...dia.com>,
Logan Gunthorpe <logang@...tatee.com>,
Hillf Danton <hdanton@...a.com>,
Christian Brauner <brauner@...nel.org>,
Linus Torvalds <torvalds@...ux-foundation.org>,
linux-fsdevel@...r.kernel.org, linux-block@...r.kernel.org,
linux-kernel@...r.kernel.org, linux-mm@...ck.org,
Christoph Hellwig <hch@....de>,
John Hubbard <jhubbard@...dia.com>
Subject: Re: [PATCH v18 09/15] iov_iter: Kill ITER_PIPE
On Thu, Apr 20, 2023 at 11:36:57PM +0100, Al Viro wrote:
> Don't get me wrong - I'd love to kill ITER_PIPE off; it's just that tons
> of ->splice_read() duplicating the corresponding ->read_iter() up to the
> point where it would call generic_file_read_iter(), modulo ignoring
> O_DIRECT case and then calling filemap_splice_read() instead... Painful
> and asking for trouble down the road.
FWIW, broken in this series:
* a bunch of 9p variants (those could probably switch to direct)
* afs
* ceph (very likely)
* ecryptfs (atime propagation)
* dax on various filesystems (probably)
* f2fs
* gfs2
* nfs
* ocfs2
* orangefs
* xfs
* zonefs (probably)
* splice from UDP sockets, unless I'm misreading something.
Your sock_splice_read() still falls back to generic_file_splice_read(),
rather than to direct_splice_read() and sockets don't have O_DIRECT
in flags. Neither do they have associated page cache ;-)
Sure, we could provide a bunch of ->splice_read(), but then we'd have to make
sure that all subsequent changes to matching ->read_iter() get duplicated -
unless they are on O_DIRECT-only paths, that is...
Powered by blists - more mailing lists