From: "Darrick J. Wong" <darrick.wong@oracle.com>
To: viro@zeniv.linux.org.uk, andreas.gruenbacher@gmail.com
Cc: xfs <linux-xfs@vger.kernel.org>,
linux-fsdevel <linux-fsdevel@vger.kernel.org>
Subject: [PATCH v2] splice: only read in as much information as there is pipe buffer space
Date: Fri, 30 Aug 2019 14:06:03 -0700 [thread overview]
Message-ID: <20190830210603.GB5340@magnolia> (raw)
In-Reply-To: <20190829161155.GA5360@magnolia>
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: Andreas Grünbacher <andreas.gruenbacher@gmail.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
---
v2: tidy up the other call site per Andreas' request
---
fs/splice.c | 17 ++++++++++++++---
1 file changed, 14 insertions(+), 3 deletions(-)
diff --git a/fs/splice.c b/fs/splice.c
index 98412721f056..2ddbace9129f 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;
@@ -1101,6 +1102,7 @@ static long do_splice(struct file *in, loff_t __user *off_in,
struct pipe_inode_info *ipipe;
struct pipe_inode_info *opipe;
loff_t offset;
+ unsigned int pipe_pages;
long ret;
ipipe = get_pipe_info(in);
@@ -1123,6 +1125,10 @@ static long do_splice(struct file *in, loff_t __user *off_in,
if ((in->f_flags | out->f_flags) & O_NONBLOCK)
flags |= SPLICE_F_NONBLOCK;
+ /* 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);
+
return splice_pipe_to_pipe(ipipe, opipe, len, flags);
}
@@ -1180,8 +1186,13 @@ 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) {
+ /* 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 prev parent reply other threads:[~2019-08-30 21:06 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-29 16:11 [PATCH] splice: only read in as much information as there is pipe buffer space Darrick J. Wong
2019-08-30 0:44 ` [RFC PATCH] generic: test splice() with pipes Darrick J. Wong
2019-09-02 2:20 ` Zorro Lang
2019-09-02 16:56 ` Darrick J. Wong
2019-09-03 3:19 ` Zorro Lang
2019-11-21 17:01 ` Darrick J. Wong
2019-11-21 18:48 ` Andreas Grünbacher
2019-11-21 19:14 ` Darrick J. Wong
2019-11-22 1:27 ` Andreas Grünbacher
2019-08-30 21:06 ` Darrick J. Wong [this message]
2019-09-05 3:42 ` [PATCH v2] splice: only read in as much information as there is pipe buffer space Darrick J. Wong
2019-09-17 13:17 ` Andreas Grünbacher
2019-09-17 16:46 ` Darrick J. Wong
2019-09-17 17:00 ` Andreas Grünbacher
2019-09-19 22:39 ` Darrick J. Wong
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