diff mbox

[1/4] vmsplice: lift import_iovec() into do_vmsplice()

Message ID 20180528222013.18402-1-viro@ZenIV.linux.org.uk (mailing list archive)
State New, archived
Headers show

Commit Message

Al Viro May 28, 2018, 10:20 p.m. UTC 
From: Al Viro <viro@zeniv.linux.org.uk>

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---
 fs/splice.c | 69 ++++++++++++++++++++++++++-----------------------------------
 1 file changed, 29 insertions(+), 40 deletions(-)

Comments

Andrey Vagin June 6, 2018, 10:57 p.m. UTC | #1 
On Mon, May 28, 2018 at 11:20:10PM +0100, Al Viro wrote:
> From: Al Viro <viro@zeniv.linux.org.uk>
> 
> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
> ---
>  fs/splice.c | 69 ++++++++++++++++++++++++++-----------------------------------
>  1 file changed, 29 insertions(+), 40 deletions(-)
> 
> diff --git a/fs/splice.c b/fs/splice.c
> index 005d09cf3fa8..920ff0b20e53 100644
> --- a/fs/splice.c
> +++ b/fs/splice.c
> @@ -1242,38 +1242,26 @@ static int pipe_to_user(struct pipe_inode_info *pipe, struct pipe_buffer *buf,
>   * For lack of a better implementation, implement vmsplice() to userspace
>   * as a simple copy of the pipes pages to the user iov.
>   */
> -static long vmsplice_to_user(struct file *file, const struct iovec __user *uiov,
> -			     unsigned long nr_segs, unsigned int flags)
> +static long vmsplice_to_user(struct file *file, struct iov_iter *iter,
> +			     unsigned int flags)
>  {
> -	struct pipe_inode_info *pipe;
> -	struct splice_desc sd;
> -	long ret;
> -	struct iovec iovstack[UIO_FASTIOV];
> -	struct iovec *iov = iovstack;
> -	struct iov_iter iter;
> +	struct pipe_inode_info *pipe = get_pipe_info(file);
> +	struct splice_desc sd = {
> +		.total_len = iov_iter_count(iter),
> +		.flags = flags,
> +		.u.data = iter
> +	};
> +	long ret = 0;
>  
> -	pipe = get_pipe_info(file);
>  	if (!pipe)
>  		return -EBADF;
>  
> -	ret = import_iovec(READ, uiov, nr_segs,
> -			   ARRAY_SIZE(iovstack), &iov, &iter);
> -	if (ret < 0)
> -		return ret;
> -
> -	sd.total_len = iov_iter_count(&iter);
> -	sd.len = 0;
> -	sd.flags = flags;
> -	sd.u.data = &iter;
> -	sd.pos = 0;
> -
>  	if (sd.total_len) {
>  		pipe_lock(pipe);
>  		ret = __splice_from_pipe(pipe, &sd, pipe_to_user);
>  		pipe_unlock(pipe);
>  	}
>  
> -	kfree(iov);
>  	return ret;
>  }
>  
> @@ -1282,14 +1270,11 @@ static long vmsplice_to_user(struct file *file, const struct iovec __user *uiov,
>   * as splice-from-memory, where the regular splice is splice-from-file (or
>   * to file). In both cases the output is a pipe, naturally.
>   */
> -static long vmsplice_to_pipe(struct file *file, const struct iovec __user *uiov,
> -			     unsigned long nr_segs, unsigned int flags)
> +static long vmsplice_to_pipe(struct file *file, struct iov_iter *iter,
> +			     unsigned int flags)
>  {
>  	struct pipe_inode_info *pipe;
> -	struct iovec iovstack[UIO_FASTIOV];
> -	struct iovec *iov = iovstack;
> -	struct iov_iter from;
> -	long ret;
> +	long ret = 0;
>  	unsigned buf_flag = 0;
>  
>  	if (flags & SPLICE_F_GIFT)
> @@ -1299,19 +1284,13 @@ static long vmsplice_to_pipe(struct file *file, const struct iovec __user *uiov,
>  	if (!pipe)
>  		return -EBADF;
>  
> -	ret = import_iovec(WRITE, uiov, nr_segs,
> -			   ARRAY_SIZE(iovstack), &iov, &from);
> -	if (ret < 0)
> -		return ret;
> -
>  	pipe_lock(pipe);
>  	ret = wait_for_space(pipe, flags);
>  	if (!ret)
> -		ret = iter_to_pipe(&from, pipe, buf_flag);
> +		ret = iter_to_pipe(iter, pipe, buf_flag);
>  	pipe_unlock(pipe);
>  	if (ret > 0)
>  		wakeup_pipe_readers(pipe);
> -	kfree(iov);
>  	return ret;
>  }
>  
> @@ -1331,29 +1310,39 @@ static long vmsplice_to_pipe(struct file *file, const struct iovec __user *uiov,
>   * Currently we punt and implement it as a normal copy, see pipe_to_user().
>   *
>   */
> -static long do_vmsplice(int fd, const struct iovec __user *iov,
> +static long do_vmsplice(int fd, const struct iovec __user *uiov,
>  			unsigned long nr_segs, unsigned int flags)
>  {
> +	struct iovec iovstack[UIO_FASTIOV];
> +	struct iovec *iov = iovstack;
> +	struct iov_iter iter;
>  	struct fd f;
>  	long error;
>  
>  	if (unlikely(flags & ~SPLICE_F_ALL))
>  		return -EINVAL;
> -	if (unlikely(nr_segs > UIO_MAXIOV))
> -		return -EINVAL;
> -	else if (unlikely(!nr_segs))
> +
> +	error = import_iovec(READ, uiov, nr_segs,
> +			   ARRAY_SIZE(iovstack), &iov, &iter);

import_iovec should be called with WRITE, if we are going to call
vmsplice_to_pipe().

> +	if (error < 0)
> +		return error;
> +
> +	if (!iov_iter_count(&iter)) {
> +		kfree(iov);
>  		return 0;
> +	}
>  
>  	error = -EBADF;
>  	f = fdget(fd);
>  	if (f.file) {
>  		if (f.file->f_mode & FMODE_WRITE)
> -			error = vmsplice_to_pipe(f.file, iov, nr_segs, flags);
> +			error = vmsplice_to_pipe(f.file, &iter, flags);
>  		else if (f.file->f_mode & FMODE_READ)
> -			error = vmsplice_to_user(f.file, iov, nr_segs, flags);
> +			error = vmsplice_to_user(f.file, &iter, flags);
>  
>  		fdput(f);
>  	}
> +	kfree(iov);
>  
>  	return error;
>  }
Andrey Vagin June 7, 2018, 5:56 p.m. UTC | #2 
On Wed, Jun 06, 2018 at 03:57:51PM -0700, Andrei Vagin wrote:
> On Mon, May 28, 2018 at 11:20:10PM +0100, Al Viro wrote:
> > From: Al Viro <viro@zeniv.linux.org.uk>
> > 
> > Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
> > ---
> >  fs/splice.c | 69 ++++++++++++++++++++++++++-----------------------------------
> >  1 file changed, 29 insertions(+), 40 deletions(-)
> > 
> > diff --git a/fs/splice.c b/fs/splice.c
> > index 005d09cf3fa8..920ff0b20e53 100644
> > --- a/fs/splice.c
> > +++ b/fs/splice.c
> > @@ -1242,38 +1242,26 @@ static int pipe_to_user(struct pipe_inode_info *pipe, struct pipe_buffer *buf,
> >   * For lack of a better implementation, implement vmsplice() to userspace
> >   * as a simple copy of the pipes pages to the user iov.
> >   */
> > -static long vmsplice_to_user(struct file *file, const struct iovec __user *uiov,
> > -			     unsigned long nr_segs, unsigned int flags)
> > +static long vmsplice_to_user(struct file *file, struct iov_iter *iter,
> > +			     unsigned int flags)
> >  {
> > -	struct pipe_inode_info *pipe;
> > -	struct splice_desc sd;
> > -	long ret;
> > -	struct iovec iovstack[UIO_FASTIOV];
> > -	struct iovec *iov = iovstack;
> > -	struct iov_iter iter;
> > +	struct pipe_inode_info *pipe = get_pipe_info(file);
> > +	struct splice_desc sd = {
> > +		.total_len = iov_iter_count(iter),
> > +		.flags = flags,
> > +		.u.data = iter
> > +	};
> > +	long ret = 0;
> >  
> > -	pipe = get_pipe_info(file);
> >  	if (!pipe)
> >  		return -EBADF;
> >  
> > -	ret = import_iovec(READ, uiov, nr_segs,
> > -			   ARRAY_SIZE(iovstack), &iov, &iter);
> > -	if (ret < 0)
> > -		return ret;
> > -
> > -	sd.total_len = iov_iter_count(&iter);
> > -	sd.len = 0;
> > -	sd.flags = flags;
> > -	sd.u.data = &iter;
> > -	sd.pos = 0;
> > -
> >  	if (sd.total_len) {
> >  		pipe_lock(pipe);
> >  		ret = __splice_from_pipe(pipe, &sd, pipe_to_user);
> >  		pipe_unlock(pipe);
> >  	}
> >  
> > -	kfree(iov);
> >  	return ret;
> >  }
> >  
> > @@ -1282,14 +1270,11 @@ static long vmsplice_to_user(struct file *file, const struct iovec __user *uiov,
> >   * as splice-from-memory, where the regular splice is splice-from-file (or
> >   * to file). In both cases the output is a pipe, naturally.
> >   */
> > -static long vmsplice_to_pipe(struct file *file, const struct iovec __user *uiov,
> > -			     unsigned long nr_segs, unsigned int flags)
> > +static long vmsplice_to_pipe(struct file *file, struct iov_iter *iter,
> > +			     unsigned int flags)
> >  {
> >  	struct pipe_inode_info *pipe;
> > -	struct iovec iovstack[UIO_FASTIOV];
> > -	struct iovec *iov = iovstack;
> > -	struct iov_iter from;
> > -	long ret;
> > +	long ret = 0;
> >  	unsigned buf_flag = 0;
> >  
> >  	if (flags & SPLICE_F_GIFT)
> > @@ -1299,19 +1284,13 @@ static long vmsplice_to_pipe(struct file *file, const struct iovec __user *uiov,
> >  	if (!pipe)
> >  		return -EBADF;
> >  
> > -	ret = import_iovec(WRITE, uiov, nr_segs,
> > -			   ARRAY_SIZE(iovstack), &iov, &from);
> > -	if (ret < 0)
> > -		return ret;
> > -
> >  	pipe_lock(pipe);
> >  	ret = wait_for_space(pipe, flags);
> >  	if (!ret)
> > -		ret = iter_to_pipe(&from, pipe, buf_flag);
> > +		ret = iter_to_pipe(iter, pipe, buf_flag);
> >  	pipe_unlock(pipe);
> >  	if (ret > 0)
> >  		wakeup_pipe_readers(pipe);
> > -	kfree(iov);
> >  	return ret;
> >  }
> >  
> > @@ -1331,29 +1310,39 @@ static long vmsplice_to_pipe(struct file *file, const struct iovec __user *uiov,
> >   * Currently we punt and implement it as a normal copy, see pipe_to_user().
> >   *
> >   */
> > -static long do_vmsplice(int fd, const struct iovec __user *iov,
> > +static long do_vmsplice(int fd, const struct iovec __user *uiov,
> >  			unsigned long nr_segs, unsigned int flags)
> >  {
> > +	struct iovec iovstack[UIO_FASTIOV];
> > +	struct iovec *iov = iovstack;
> > +	struct iov_iter iter;
> >  	struct fd f;
> >  	long error;
> >  
> >  	if (unlikely(flags & ~SPLICE_F_ALL))
> >  		return -EINVAL;
> > -	if (unlikely(nr_segs > UIO_MAXIOV))
> > -		return -EINVAL;
> > -	else if (unlikely(!nr_segs))
> > +
> > +	error = import_iovec(READ, uiov, nr_segs,
> > +			   ARRAY_SIZE(iovstack), &iov, &iter);
> 
> import_iovec should be called with WRITE, if we are going to call
> vmsplice_to_pipe().

We caught this issue, when we run CRIU tests for
https://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs.git/log/?h=for-next

CRIU fails with errors like this:

pie: 38: Error (criu/pie/parasite.c:89): Can't splice pages to pipe (-14/2/0)

Thanks,
Andrei

> 
> > +	if (error < 0)
> > +		return error;
> > +
> > +	if (!iov_iter_count(&iter)) {
> > +		kfree(iov);
> >  		return 0;
> > +	}
> >  
> >  	error = -EBADF;
> >  	f = fdget(fd);
> >  	if (f.file) {
> >  		if (f.file->f_mode & FMODE_WRITE)
> > -			error = vmsplice_to_pipe(f.file, iov, nr_segs, flags);
> > +			error = vmsplice_to_pipe(f.file, &iter, flags);
> >  		else if (f.file->f_mode & FMODE_READ)
> > -			error = vmsplice_to_user(f.file, iov, nr_segs, flags);
> > +			error = vmsplice_to_user(f.file, &iter, flags);
> >  
> >  		fdput(f);
> >  	}
> > +	kfree(iov);
> >  
> >  	return error;
> >  }
Cyrill Gorcunov June 11, 2018, 8:14 p.m. UTC | #3 
On Thu, Jun 7, 2018 at 10:07 PM Andrei Vagin <avagin@virtuozzo.com> wrote:
>
...
> > > +
> > > +   error = import_iovec(READ, uiov, nr_segs,
> > > +                      ARRAY_SIZE(iovstack), &iov, &iter);
> >
> > import_iovec should be called with WRITE, if we are going to call
> > vmsplice_to_pipe().
>
> We caught this issue, when we run CRIU tests for
> https://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs.git/log/?h=for-next
>
> CRIU fails with errors like this:
>
> pie: 38: Error (criu/pie/parasite.c:89): Can't splice pages to pipe (-14/2/0)
>
It is already in the master tree, or still in the linux-next?
Al Viro June 11, 2018, 8:16 p.m. UTC | #4 
On Mon, Jun 11, 2018 at 11:14:55PM +0300, Cyrill Gorcunov wrote:
> On Thu, Jun 7, 2018 at 10:07 PM Andrei Vagin <avagin@virtuozzo.com> wrote:
> >
> ...
> > > > +
> > > > +   error = import_iovec(READ, uiov, nr_segs,
> > > > +                      ARRAY_SIZE(iovstack), &iov, &iter);
> > >
> > > import_iovec should be called with WRITE, if we are going to call
> > > vmsplice_to_pipe().
> >
> > We caught this issue, when we run CRIU tests for
> > https://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs.git/log/?h=for-next
> >
> > CRIU fails with errors like this:
> >
> > pie: 38: Error (criu/pie/parasite.c:89): Can't splice pages to pipe (-14/2/0)
> >
> It is already in the master tree, or still in the linux-next?

Still in -next; I have a fixed variant, hadn't pushed it out yet.
Cyrill Gorcunov June 11, 2018, 8:18 p.m. UTC | #5 
On Mon, Jun 11, 2018 at 11:16 PM Al Viro <viro@zeniv.linux.org.uk> wrote:
...
> > It is already in the master tree, or still in the linux-next?
>
> Still in -next; I have a fixed variant, hadn't pushed it out yet.

Thanks a lot, Al!
Andrey Vagin June 14, 2018, 10:22 p.m. UTC | #6 
On Mon, Jun 11, 2018 at 09:16:56PM +0100, Al Viro wrote:
> On Mon, Jun 11, 2018 at 11:14:55PM +0300, Cyrill Gorcunov wrote:
> > On Thu, Jun 7, 2018 at 10:07 PM Andrei Vagin <avagin@virtuozzo.com> wrote:
> > >
> > ...
> > > > > +
> > > > > +   error = import_iovec(READ, uiov, nr_segs,
> > > > > +                      ARRAY_SIZE(iovstack), &iov, &iter);
> > > >
> > > > import_iovec should be called with WRITE, if we are going to call
> > > > vmsplice_to_pipe().
> > >
> > > We caught this issue, when we run CRIU tests for
> > > https://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs.git/log/?h=for-next
> > >
> > > CRIU fails with errors like this:
> > >
> > > pie: 38: Error (criu/pie/parasite.c:89): Can't splice pages to pipe (-14/2/0)
> > >
> > It is already in the master tree, or still in the linux-next?
> 
> Still in -next; I have a fixed variant, hadn't pushed it out yet.

Al, can I ask you to push the fixed variant to -next or revert this
one. We have a robot which regularly runs CRIU tests on -next, and now it
is blocked by this issue.

Thanks,
Andrei
diff mbox

Patch

diff --git a/fs/splice.c b/fs/splice.c
index 005d09cf3fa8..920ff0b20e53 100644
--- a/fs/splice.c
+++ b/fs/splice.c
@@ -1242,38 +1242,26 @@  static int pipe_to_user(struct pipe_inode_info *pipe, struct pipe_buffer *buf,
  * For lack of a better implementation, implement vmsplice() to userspace
  * as a simple copy of the pipes pages to the user iov.
  */
-static long vmsplice_to_user(struct file *file, const struct iovec __user *uiov,
-			     unsigned long nr_segs, unsigned int flags)
+static long vmsplice_to_user(struct file *file, struct iov_iter *iter,
+			     unsigned int flags)
 {
-	struct pipe_inode_info *pipe;
-	struct splice_desc sd;
-	long ret;
-	struct iovec iovstack[UIO_FASTIOV];
-	struct iovec *iov = iovstack;
-	struct iov_iter iter;
+	struct pipe_inode_info *pipe = get_pipe_info(file);
+	struct splice_desc sd = {
+		.total_len = iov_iter_count(iter),
+		.flags = flags,
+		.u.data = iter
+	};
+	long ret = 0;
 
-	pipe = get_pipe_info(file);
 	if (!pipe)
 		return -EBADF;
 
-	ret = import_iovec(READ, uiov, nr_segs,
-			   ARRAY_SIZE(iovstack), &iov, &iter);
-	if (ret < 0)
-		return ret;
-
-	sd.total_len = iov_iter_count(&iter);
-	sd.len = 0;
-	sd.flags = flags;
-	sd.u.data = &iter;
-	sd.pos = 0;
-
 	if (sd.total_len) {
 		pipe_lock(pipe);
 		ret = __splice_from_pipe(pipe, &sd, pipe_to_user);
 		pipe_unlock(pipe);
 	}
 
-	kfree(iov);
 	return ret;
 }
 
@@ -1282,14 +1270,11 @@  static long vmsplice_to_user(struct file *file, const struct iovec __user *uiov,
  * as splice-from-memory, where the regular splice is splice-from-file (or
  * to file). In both cases the output is a pipe, naturally.
  */
-static long vmsplice_to_pipe(struct file *file, const struct iovec __user *uiov,
-			     unsigned long nr_segs, unsigned int flags)
+static long vmsplice_to_pipe(struct file *file, struct iov_iter *iter,
+			     unsigned int flags)
 {
 	struct pipe_inode_info *pipe;
-	struct iovec iovstack[UIO_FASTIOV];
-	struct iovec *iov = iovstack;
-	struct iov_iter from;
-	long ret;
+	long ret = 0;
 	unsigned buf_flag = 0;
 
 	if (flags & SPLICE_F_GIFT)
@@ -1299,19 +1284,13 @@  static long vmsplice_to_pipe(struct file *file, const struct iovec __user *uiov,
 	if (!pipe)
 		return -EBADF;
 
-	ret = import_iovec(WRITE, uiov, nr_segs,
-			   ARRAY_SIZE(iovstack), &iov, &from);
-	if (ret < 0)
-		return ret;
-
 	pipe_lock(pipe);
 	ret = wait_for_space(pipe, flags);
 	if (!ret)
-		ret = iter_to_pipe(&from, pipe, buf_flag);
+		ret = iter_to_pipe(iter, pipe, buf_flag);
 	pipe_unlock(pipe);
 	if (ret > 0)
 		wakeup_pipe_readers(pipe);
-	kfree(iov);
 	return ret;
 }
 
@@ -1331,29 +1310,39 @@  static long vmsplice_to_pipe(struct file *file, const struct iovec __user *uiov,
  * Currently we punt and implement it as a normal copy, see pipe_to_user().
  *
  */
-static long do_vmsplice(int fd, const struct iovec __user *iov,
+static long do_vmsplice(int fd, const struct iovec __user *uiov,
 			unsigned long nr_segs, unsigned int flags)
 {
+	struct iovec iovstack[UIO_FASTIOV];
+	struct iovec *iov = iovstack;
+	struct iov_iter iter;
 	struct fd f;
 	long error;
 
 	if (unlikely(flags & ~SPLICE_F_ALL))
 		return -EINVAL;
-	if (unlikely(nr_segs > UIO_MAXIOV))
-		return -EINVAL;
-	else if (unlikely(!nr_segs))
+
+	error = import_iovec(READ, uiov, nr_segs,
+			   ARRAY_SIZE(iovstack), &iov, &iter);
+	if (error < 0)
+		return error;
+
+	if (!iov_iter_count(&iter)) {
+		kfree(iov);
 		return 0;
+	}
 
 	error = -EBADF;
 	f = fdget(fd);
 	if (f.file) {
 		if (f.file->f_mode & FMODE_WRITE)
-			error = vmsplice_to_pipe(f.file, iov, nr_segs, flags);
+			error = vmsplice_to_pipe(f.file, &iter, flags);
 		else if (f.file->f_mode & FMODE_READ)
-			error = vmsplice_to_user(f.file, iov, nr_segs, flags);
+			error = vmsplice_to_user(f.file, &iter, flags);
 
 		fdput(f);
 	}
+	kfree(iov);
 
 	return error;
 }