From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-qt0-f175.google.com ([209.85.216.175]:34879 "EHLO mail-qt0-f175.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S965974AbdAKMUR (ORCPT ); Wed, 11 Jan 2017 07:20:17 -0500 Received: by mail-qt0-f175.google.com with SMTP id x49so127215342qtc.2 for ; Wed, 11 Jan 2017 04:20:17 -0800 (PST) Message-ID: <1484137213.2621.6.camel@redhat.com> Subject: Re: [PATCH RESEND] splice: introduce FMODE_SPLICE_READ and FMODE_SPLICE_WRITE From: Jeff Layton To: Johannes Thumshirn , Alexander Viro Cc: "J . Bruce Fields" , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, mbenes@suse.cz, jack@suse.cz Date: Wed, 11 Jan 2017 07:20:13 -0500 In-Reply-To: <20170111095139.17783-1-jthumshirn@suse.de> References: <20170111095139.17783-1-jthumshirn@suse.de> Content-Type: text/plain; charset="UTF-8" Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-fsdevel-owner@vger.kernel.org List-ID: On Wed, 2017-01-11 at 10:51 +0100, Johannes Thumshirn wrote: > Introduce FMODE_SPLICE_READ and FMODE_SPLICE_WRITE. These modes check > whether it is legal to read or write a file using splice. Both get > automatically set on regular files and are not checked when a 'struct > fileoperations' includes the splice_{read,write} methods. > Could you add a description of the problem that this solves? I assume you hit a problem trying to splice to/from a non-regular file, but it'd be good to know what that problem was. Thanks, > Suggested-by: Linus Torvalds > Cc: Al Viro > Signed-off-by: Johannes Thumshirn > --- > fs/open.c | 4 ++++ > fs/splice.c | 6 ++++++ > include/linux/fs.h | 5 +++++ > 3 files changed, 15 insertions(+) > > diff --git a/fs/open.c b/fs/open.c > index 9921f70..b71259c 100644 > --- a/fs/open.c > +++ b/fs/open.c > @@ -733,6 +733,10 @@ static int do_dentry_open(struct file *f, > if (S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode)) > f->f_mode |= FMODE_ATOMIC_POS; > > + if (S_ISREG(inode->i_mode)) > + f->f_mode |= FMODE_SPLICE_WRITE | FMODE_SPLICE_READ; > + > + > f->f_op = fops_get(inode->i_fop); > if (unlikely(WARN_ON(!f->f_op))) { > error = -ENODEV; > diff --git a/fs/splice.c b/fs/splice.c > index 873d831..b0cfcb2 100644 > --- a/fs/splice.c > +++ b/fs/splice.c > @@ -397,6 +397,9 @@ static ssize_t default_file_splice_read(struct file *in, loff_t *ppos, > if (pipe->nrbufs == pipe->buffers) > return -EAGAIN; > > + if (unlikely(!(in->f_mode & FMODE_SPLICE_READ))) > + return -EINVAL; > + > /* > * Try to keep page boundaries matching to source pagecache ones - > * it probably won't be much help, but... > @@ -825,6 +828,9 @@ static ssize_t default_file_splice_write(struct pipe_inode_info *pipe, > { > ssize_t ret; > > + if (unlikely(!(out->f_mode & FMODE_SPLICE_WRITE))) > + return -EINVAL; > + > ret = splice_from_pipe(pipe, out, ppos, len, flags, write_pipe_buf); > if (ret > 0) > *ppos += ret; > diff --git a/include/linux/fs.h b/include/linux/fs.h > index 2ba0743..30477c5 100644 > --- a/include/linux/fs.h > +++ b/include/linux/fs.h > @@ -143,6 +143,11 @@ typedef int (dio_iodone_t)(struct kiocb *iocb, loff_t offset, > /* File was opened by fanotify and shouldn't generate fanotify events */ > #define FMODE_NONOTIFY ((__force fmode_t)0x4000000) > > +/* File can be read using splice */ > +#define FMODE_SPLICE_READ ((__force fmode_t)0x8000000) > +/* File can be written using splice */ > +#define FMODE_SPLICE_WRITE ((__force fmode_t)0x10000000) > + > /* > * Flag for rw_copy_check_uvector and compat_rw_copy_check_uvector > * that indicates that they should check the contents of the iovec are -- Jeff Layton