diff mbox series

[1/2] fs/aio: Use kmap_local() instead of kmap()

Message ID 20230118152603.28301-1-kent.overstreet@linux.dev
State New
Headers
Series [1/2] fs/aio: Use kmap_local() instead of kmap() |

Commit Message

Kent Overstreet Jan. 18, 2023, 3:26 p.m. UTC 
  Originally, we used kmap() instead of kmap_atomic() for reading events
out of the completion ringbuffer because we're using copy_to_user(),
which can fault.

Now that kmap_local() is a thing, use that instead.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
Cc: Benjamin LaHaise <bcrl@kvack.org
Cc: linux-aio@kvack.org
Cc: linux-fsdevel@vger.kernel.org
---
 fs/aio.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

Comments

Jeff Moyer Jan. 18, 2023, 6:19 p.m. UTC | #1 
Hi, Kent,

Kent Overstreet <kent.overstreet@linux.dev> writes:

> Originally, we used kmap() instead of kmap_atomic() for reading events
> out of the completion ringbuffer because we're using copy_to_user(),
> which can fault.
>
> Now that kmap_local() is a thing, use that instead.

This has already been proposed as part of a more comprehensive patch:
  https://lore.kernel.org/linux-fsdevel/20230109175629.9482-1-fmdefrancesco@gmail.com/

Would you be willing to review that one?

Thanks!
Jeff

>
> Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
> Cc: Benjamin LaHaise <bcrl@kvack.org
> Cc: linux-aio@kvack.org
> Cc: linux-fsdevel@vger.kernel.org
> ---
>  fs/aio.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/fs/aio.c b/fs/aio.c
> index 5b2ff20ad3..3f795ed2a2 100644
> --- a/fs/aio.c
> +++ b/fs/aio.c
> @@ -1246,10 +1246,10 @@ static long aio_read_events_ring(struct kioctx *ctx,
>  		avail = min(avail, nr - ret);
>  		avail = min_t(long, avail, AIO_EVENTS_PER_PAGE - pos);
>  
> -		ev = kmap(page);
> +		ev = kmap_local_page(page);
>  		copy_ret = copy_to_user(event + ret, ev + pos,
>  					sizeof(*ev) * avail);
> -		kunmap(page);
> +		kunmap_local(ev);
>  
>  		if (unlikely(copy_ret)) {
>  			ret = -EFAULT;
diff mbox series

Patch

diff --git a/fs/aio.c b/fs/aio.c
index 5b2ff20ad3..3f795ed2a2 100644
--- a/fs/aio.c
+++ b/fs/aio.c
@@ -1246,10 +1246,10 @@  static long aio_read_events_ring(struct kioctx *ctx,
 		avail = min(avail, nr - ret);
 		avail = min_t(long, avail, AIO_EVENTS_PER_PAGE - pos);
 
-		ev = kmap(page);
+		ev = kmap_local_page(page);
 		copy_ret = copy_to_user(event + ret, ev + pos,
 					sizeof(*ev) * avail);
-		kunmap(page);
+		kunmap_local(ev);
 
 		if (unlikely(copy_ret)) {
 			ret = -EFAULT;