From: David Howells <dhowells@redhat.com>
To: Jeff Layton <jlayton@redhat.com>
Cc: dhowells@redhat.com, linux-fsdevel@vger.kernel.org,
"Matthew Wilcox (Oracle)" <willy@infradead.org>,
Anna Schumaker <anna.schumaker@netapp.com>,
Steve French <sfrench@samba.org>,
Dominique Martinet <asmadeus@codewreck.org>,
Mike Marshall <hubcap@omnibond.com>,
David Wysochanski <dwysocha@redhat.com>,
Shyam Prasad N <nspmangalore@gmail.com>,
Miklos Szeredi <miklos@szeredi.hu>,
Linus Torvalds <torvalds@linux-foundation.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,
devel@lists.orangefs.org, linux-mm@kvack.org,
linux-kernel@vger.kernel.org
Subject: Re: [RFC PATCH 03/12] netfs: Remove netfs_read_subrequest::transferred
Date: Wed, 21 Jul 2021 19:54:52 +0100 [thread overview]
Message-ID: <298117.1626893692@warthog.procyon.org.uk> (raw)
In-Reply-To: <e7a3b850e8a42845f4e020c7642743b3dce2b9f1.camel@redhat.com>
Jeff Layton <jlayton@redhat.com> wrote:
> The above two deltas seem like they should have been in patch #2.
Yeah. Looks like at least partially so.
> > @@ -635,15 +625,8 @@ void netfs_subreq_terminated(struct netfs_read_subrequest *subreq,
> > goto failed;
> > }
> >
> > - if (WARN(transferred_or_error > subreq->len - subreq->transferred,
> > - "Subreq overread: R%x[%x] %zd > %zu - %zu",
> > - rreq->debug_id, subreq->debug_index,
> > - transferred_or_error, subreq->len, subreq->transferred))
> > - transferred_or_error = subreq->len - subreq->transferred;
> > -
> > subreq->error = 0;
> > - subreq->transferred += transferred_or_error;
> > - if (subreq->transferred < subreq->len)
> > + if (iov_iter_count(&subreq->iter))
> > goto incomplete;
> >
>
> I must be missing it, but where does subreq->iter get advanced to the
> end of the current read? If you're getting rid of subreq->transferred
> then I think that has to happen above, no?
For afs, afs_req_issue_op() points fsreq->iter at the subrequest iterator and
calls afs_fetch_data(). Thereafter, we wend our way to
afs_deliver_fs_fetch_data() or yfs_deliver_fs_fetch_data() which set
call->iter to point to that iterator and then call afs_extract_data() which
passes it to rxrpc_kernel_recv_data(), which eventually passes it to
skb_copy_datagram_iter(), which advances the iterator.
For the cache, the subrequest iterator is passed to the cache backend by
netfs_read_from_cache(). This would be cachefiles_read() which calls
vfs_iocb_iter_read() which I thought advances the iterator (leastways,
filemap_read() keeps going until iov_iter_count() reaches 0 or some other stop
condition occurs and doesn't thereafter call iov_iter_revert()).
David
next prev parent reply other threads:[~2021-07-21 18:55 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-21 13:44 David Howells
2021-07-21 13:44 ` [RFC PATCH 01/12] afs: Sort out symlink reading David Howells
2021-07-21 16:20 ` Jeff Layton
2021-07-26 9:44 ` David Howells
2021-07-21 13:44 ` [RFC PATCH 02/12] netfs: Add an iov_iter to the read subreq for the network fs/cache to use David Howells
2021-07-21 17:16 ` Jeff Layton
2021-07-21 17:20 ` David Howells
2021-07-21 13:45 ` [RFC PATCH 03/12] netfs: Remove netfs_read_subrequest::transferred David Howells
2021-07-21 17:43 ` Jeff Layton
2021-07-21 18:54 ` David Howells [this message]
2021-07-21 19:00 ` Jeff Layton
2021-07-21 13:45 ` [RFC PATCH 04/12] netfs: Use a buffer in netfs_read_request and add pages to it David Howells
2021-07-21 13:45 ` [RFC PATCH 05/12] netfs: Add a netfs inode context David Howells
2021-07-21 13:46 ` [RFC PATCH 06/12] netfs: Keep lists of pending, active, dirty and flushed regions David Howells
2021-07-21 13:46 ` [RFC PATCH 07/12] netfs: Initiate write request from a dirty region David Howells
2021-07-21 13:46 ` [RFC PATCH 08/12] netfs: Keep dirty mark for pages with more than one " David Howells
2021-07-21 13:46 ` [RFC PATCH 09/12] netfs: Send write request to multiple destinations David Howells
2021-07-21 13:46 ` [RFC PATCH 10/12] netfs: Do encryption in write preparatory phase David Howells
2021-07-21 13:47 ` [RFC PATCH 11/12] netfs: Put a list of regions in /proc/fs/netfs/regions David Howells
2021-07-21 13:47 ` [RFC PATCH 12/12] netfs: Export some read-request ref functions David Howells
2021-07-21 14:00 ` [RFC PATCH 00/12] netfs: Experimental write helpers, fscrypt and compression David Howells
2021-07-21 18:42 ` [RFC PATCH 13/12] netfs: Do copy-to-cache-on-read through VM writeback David Howells
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