| Message ID | 20191019161138.GA6726@magnolia (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [v4] splice: only read in as much information as there is pipe buffer space | expand |
Ping? Can /someone/ please review this? --D On Sat, Oct 19, 2019 at 09:11:38AM -0700, Darrick J. Wong wrote: > 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> > --- > v4: use size_t for pipe_pages > --- > fs/splice.c | 14 +++++++++++--- > 1 file changed, 11 insertions(+), 3 deletions(-) > > diff --git a/fs/splice.c b/fs/splice.c > index 98412721f056..9b9b22d2215a 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) { > + size_t 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, 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) { > + size_t pipe_pages; > + > + /* Don't try to read more the pipe has space for. */ > + pipe_pages = opipe->buffers - opipe->nrbufs; > + len = min(len, pipe_pages << PAGE_SHIFT); > + > ret = do_splice_to(in, &offset, opipe, len, flags); > + } > pipe_unlock(opipe); > if (ret > 0) > wakeup_pipe_readers(opipe);
On Sat, Oct 19, 2019 at 6:14 PM Darrick J. Wong <darrick.wong@oracle.com> wrote: > 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> Reviewed-by: Andreas Grünbacher <andreas.gruenbacher@gmail.com> > Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com> > --- > v4: use size_t for pipe_pages > --- > fs/splice.c | 14 +++++++++++--- > 1 file changed, 11 insertions(+), 3 deletions(-) > > diff --git a/fs/splice.c b/fs/splice.c > index 98412721f056..9b9b22d2215a 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) { > + size_t 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, 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) { > + size_t pipe_pages; > + > + /* Don't try to read more the pipe has space for. */ > + pipe_pages = opipe->buffers - opipe->nrbufs; > + len = min(len, pipe_pages << PAGE_SHIFT); > + > ret = do_splice_to(in, &offset, opipe, len, flags); > + } > pipe_unlock(opipe); > if (ret > 0) > wakeup_pipe_readers(opipe);
On Thu, Nov 21, 2019 at 06:57:55PM +0100, Andreas Gruenbacher wrote: > On Sat, Oct 19, 2019 at 6:14 PM Darrick J. Wong <darrick.wong@oracle.com> wrote: > > 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> > > Reviewed-by: Andreas Grünbacher <andreas.gruenbacher@gmail.com> Cool, thanks. I'll try to push this to Linus next week. --D > > Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com> > > --- > > v4: use size_t for pipe_pages > > --- > > fs/splice.c | 14 +++++++++++--- > > 1 file changed, 11 insertions(+), 3 deletions(-) > > > > diff --git a/fs/splice.c b/fs/splice.c > > index 98412721f056..9b9b22d2215a 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) { > > + size_t 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, 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) { > > + size_t pipe_pages; > > + > > + /* Don't try to read more the pipe has space for. */ > > + pipe_pages = opipe->buffers - opipe->nrbufs; > > + len = min(len, pipe_pages << PAGE_SHIFT); > > + > > ret = do_splice_to(in, &offset, opipe, len, flags); > > + } > > pipe_unlock(opipe); > > if (ret > 0) > > wakeup_pipe_readers(opipe); >
Am Fr., 22. Nov. 2019 um 02:24 Uhr schrieb Darrick J. Wong <darrick.wong@oracle.com>: > On Thu, Nov 21, 2019 at 06:57:55PM +0100, Andreas Gruenbacher wrote: > > On Sat, Oct 19, 2019 at 6:14 PM Darrick J. Wong <darrick.wong@oracle.com> wrote: > > > 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> > > > > Reviewed-by: Andreas Grünbacher <andreas.gruenbacher@gmail.com> > > Cool, thanks. I'll try to push this to Linus next week. That would be great, thanks. Andreas
diff --git a/fs/splice.c b/fs/splice.c index 98412721f056..9b9b22d2215a 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) { + size_t 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, 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) { + size_t pipe_pages; + + /* Don't try to read more the pipe has space for. */ + pipe_pages = opipe->buffers - opipe->nrbufs; + len = min(len, pipe_pages << PAGE_SHIFT); + ret = do_splice_to(in, &offset, opipe, len, flags); + } pipe_unlock(opipe); if (ret > 0) wakeup_pipe_readers(opipe);