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[68.20.15.154]) by smtp.gmail.com with ESMTPSA id t6sm1744741qkg.75.2021.07.21.10.16.56 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 21 Jul 2021 10:16:57 -0700 (PDT) Message-ID: <0555748529d483fb9b69eceb56bf9ebc1efceaf1.camel@redhat.com> Subject: Re: [RFC PATCH 02/12] netfs: Add an iov_iter to the read subreq for the network fs/cache to use From: Jeff Layton To: David Howells , linux-fsdevel@vger.kernel.org Cc: "Matthew Wilcox (Oracle)" , Anna Schumaker , Steve French , Dominique Martinet , Mike Marshall , David Wysochanski , Shyam Prasad N , Miklos Szeredi , Linus Torvalds , 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 Date: Wed, 21 Jul 2021 13:16:56 -0400 In-Reply-To: <162687509306.276387.7579641363406546284.stgit@warthog.procyon.org.uk> References: <162687506932.276387.14456718890524355509.stgit@warthog.procyon.org.uk> <162687509306.276387.7579641363406546284.stgit@warthog.procyon.org.uk> User-Agent: Evolution 3.40.3 (3.40.3-1.fc34) MIME-Version: 1.0 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset="ISO-8859-15" Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: 63909D000495 X-Stat-Signature: ikczerhicptzz1rrhg3b98etwr49ka1p Authentication-Results: imf15.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=YavKRb71; spf=none (imf15.hostedemail.com: domain of jlayton@redhat.com has no SPF policy when checking 216.205.24.124) smtp.mailfrom=jlayton@redhat.com; dmarc=pass (policy=none) header.from=redhat.com X-HE-Tag: 1626887821-495635 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Wed, 2021-07-21 at 14:44 +0100, David Howells wrote: > Add an iov_iter to the read subrequest and set it up to define the > destination buffer to write into. This will allow future patches to point > to a bounce buffer instead for purposes of handling oversize writes, > decryption (where we want to save the encrypted data to the cache) and > decompression. > > Signed-off-by: David Howells > --- > > fs/afs/file.c | 6 +----- > fs/netfs/read_helper.c | 5 ++++- > include/linux/netfs.h | 2 ++ > 3 files changed, 7 insertions(+), 6 deletions(-) > > diff --git a/fs/afs/file.c b/fs/afs/file.c > index c9c21ad0e7c9..ca529f23515a 100644 > --- a/fs/afs/file.c > +++ b/fs/afs/file.c > @@ -319,11 +319,7 @@ static void afs_req_issue_op(struct netfs_read_subrequest *subreq) > fsreq->len = subreq->len - subreq->transferred; > fsreq->key = subreq->rreq->netfs_priv; > fsreq->vnode = vnode; > - fsreq->iter = &fsreq->def_iter; > - > - iov_iter_xarray(&fsreq->def_iter, READ, > - &fsreq->vnode->vfs_inode.i_mapping->i_pages, > - fsreq->pos, fsreq->len); > + fsreq->iter = &subreq->iter; > > afs_fetch_data(fsreq->vnode, fsreq); > } > diff --git a/fs/netfs/read_helper.c b/fs/netfs/read_helper.c > index 0b6cd3b8734c..715f3e9c380d 100644 > --- a/fs/netfs/read_helper.c > +++ b/fs/netfs/read_helper.c > @@ -150,7 +150,7 @@ static void netfs_clear_unread(struct netfs_read_subrequest *subreq) > { > struct iov_iter iter; > > - iov_iter_xarray(&iter, WRITE, &subreq->rreq->mapping->i_pages, > + iov_iter_xarray(&iter, READ, &subreq->rreq->mapping->i_pages, What's up with the WRITE -> READ change here? Was that a preexisting bug? > subreq->start + subreq->transferred, > subreq->len - subreq->transferred); > iov_iter_zero(iov_iter_count(&iter), &iter); > @@ -745,6 +745,9 @@ netfs_rreq_prepare_read(struct netfs_read_request *rreq, > if (WARN_ON(subreq->len == 0)) > source = NETFS_INVALID_READ; > > + iov_iter_xarray(&subreq->iter, READ, &rreq->mapping->i_pages, > + subreq->start, subreq->len); > + > out: > subreq->source = source; > trace_netfs_sreq(subreq, netfs_sreq_trace_prepare); > diff --git a/include/linux/netfs.h b/include/linux/netfs.h > index fe9887768292..5e4fafcc9480 100644 > --- a/include/linux/netfs.h > +++ b/include/linux/netfs.h > @@ -17,6 +17,7 @@ > #include > #include > #include > +#include > > /* > * Overload PG_private_2 to give us PG_fscache - this is used to indicate that > @@ -112,6 +113,7 @@ struct netfs_cache_resources { > struct netfs_read_subrequest { > struct netfs_read_request *rreq; /* Supervising read request */ > struct list_head rreq_link; /* Link in rreq->subrequests */ > + struct iov_iter iter; /* Iterator for this subrequest */ > loff_t start; /* Where to start the I/O */ > size_t len; /* Size of the I/O */ > size_t transferred; /* Amount of data transferred */ > > -- Jeff Layton