From: "Darrick J. Wong" <darrick.wong@oracle.com>
To: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Andreas Gruenbacher <agruenba@redhat.com>,
Rasmus Villemoes <linux@rasmusvillemoes.dk>,
linux-fsdevel <linux-fsdevel@vger.kernel.org>,
Bob Peterson <rpeterso@redhat.com>
Subject: [PATCH v3] splice: only read in as much information as there is pipe buffer space
Date: Mon, 14 Oct 2019 15:09:40 -0700 [thread overview]
Message-ID: <20191014220940.GF13098@magnolia> (raw)
From: Darrick J. Wong <darrick.wong@oracle.com>
Andreas Grünbacher reports that on the two filesystems that support
iomap directio, it's possible for splice() to return -EAGAIN (instead of
a short splice) if the pipe being written to has less space available in
its pipe buffers than the length supplied by the calling process.
Months ago we fixed splice_direct_to_actor to clamp the length of the
read request to the size of the splice pipe. Do the same to do_splice.
Fixes: 17614445576b6 ("splice: don't read more than available pipe space")
Reported-by: syzbot+3c01db6025f26530cf8d@syzkaller.appspotmail.com
Reported-by: Andreas Grünbacher <andreas.gruenbacher@gmail.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
---
fs/splice.c | 14 +++++++++++---
1 file changed, 11 insertions(+), 3 deletions(-)
diff --git a/fs/splice.c b/fs/splice.c
index 98412721f056..e509239d7e06 100644
--- a/fs/splice.c
+++ b/fs/splice.c
@@ -945,12 +945,13 @@ ssize_t splice_direct_to_actor(struct file *in, struct splice_desc *sd,
WARN_ON_ONCE(pipe->nrbufs != 0);
while (len) {
+ unsigned int pipe_pages;
size_t read_len;
loff_t pos = sd->pos, prev_pos = pos;
/* Don't try to read more the pipe has space for. */
- read_len = min_t(size_t, len,
- (pipe->buffers - pipe->nrbufs) << PAGE_SHIFT);
+ pipe_pages = pipe->buffers - pipe->nrbufs;
+ read_len = min(len, (size_t)pipe_pages << PAGE_SHIFT);
ret = do_splice_to(in, &pos, pipe, read_len, flags);
if (unlikely(ret <= 0))
goto out_release;
@@ -1180,8 +1181,15 @@ static long do_splice(struct file *in, loff_t __user *off_in,
pipe_lock(opipe);
ret = wait_for_space(opipe, flags);
- if (!ret)
+ if (!ret) {
+ unsigned int pipe_pages;
+
+ /* Don't try to read more the pipe has space for. */
+ pipe_pages = opipe->buffers - opipe->nrbufs;
+ len = min(len, (size_t)pipe_pages << PAGE_SHIFT);
+
ret = do_splice_to(in, &offset, opipe, len, flags);
+ }
pipe_unlock(opipe);
if (ret > 0)
wakeup_pipe_readers(opipe);
next reply other threads:[~2019-10-14 22:12 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-14 22:09 Darrick J. Wong [this message]
2019-10-15 11:31 ` [PATCH v3] splice: only read in as much information as there is pipe buffer space Andreas Grünbacher
2019-10-16 3:12 ` Dave Chinner
2019-10-16 18:54 ` Darrick J. Wong
2019-10-16 18:45 ` Eric Biggers
2019-10-16 18:52 ` Darrick J. Wong
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20191014220940.GF13098@magnolia \
--to=darrick.wong@oracle.com \
--cc=agruenba@redhat.com \
--cc=linux-fsdevel@vger.kernel.org \
--cc=linux@rasmusvillemoes.dk \
--cc=rpeterso@redhat.com \
--cc=viro@zeniv.linux.org.uk \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).