[v6,15/24] fs/io_uring: set FOLL_PIN via pin_user_pages()

Commit Message

John Hubbard Nov. 19, 2019, 8:16 a.m. UTC

Convert fs/io_uring to use the new pin_user_pages() call, which sets
FOLL_PIN. Setting FOLL_PIN is now required for code that requires
tracking of pinned pages, and therefore for any code that calls
put_user_page().

In partial anticipation of this work, the io_uring code was already
calling put_user_page() instead of put_page(). Therefore, in order to
convert from the get_user_pages()/put_page() model, to the
pin_user_pages()/put_user_page() model, the only change required
here is to change get_user_pages() to pin_user_pages().

Reviewed-by: Jan Kara <[e-mail]>
Signed-off-by: John Hubbard <[e-mail]>
---
 fs/io_uring.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Comments

Jens Axboe Nov. 19, 2019, 4:10 p.m. UTC | #1

On 11/19/19 1:16 AM, John Hubbard wrote:
> Convert fs/io_uring to use the new pin_user_pages() call, which sets
> FOLL_PIN. Setting FOLL_PIN is now required for code that requires
> tracking of pinned pages, and therefore for any code that calls
> put_user_page().
> 
> In partial anticipation of this work, the io_uring code was already
> calling put_user_page() instead of put_page(). Therefore, in order to
> convert from the get_user_pages()/put_page() model, to the
> pin_user_pages()/put_user_page() model, the only change required
> here is to change get_user_pages() to pin_user_pages().
> 
> Reviewed-by: Jan Kara <[e-mail]>
> Signed-off-by: John Hubbard <[e-mail]>

You dropped my reviewed-by now... Given the file, you'd probably want
to keep that.

John Hubbard Nov. 20, 2019, 7:03 a.m. UTC | #2

On 11/19/19 8:10 AM, Jens Axboe wrote:
> On 11/19/19 1:16 AM, John Hubbard wrote:
>> Convert fs/io_uring to use the new pin_user_pages() call, which sets
>> FOLL_PIN. Setting FOLL_PIN is now required for code that requires
>> tracking of pinned pages, and therefore for any code that calls
>> put_user_page().
>>
>> In partial anticipation of this work, the io_uring code was already
>> calling put_user_page() instead of put_page(). Therefore, in order to
>> convert from the get_user_pages()/put_page() model, to the
>> pin_user_pages()/put_user_page() model, the only change required
>> here is to change get_user_pages() to pin_user_pages().
>>
>> Reviewed-by: Jan Kara <[e-mail]>
>> Signed-off-by: John Hubbard <[e-mail]>
> 
> You dropped my reviewed-by now... Given the file, you'd probably want
> to keep that.

Hi Jens,

Yes, I was being too conservative I guess. I changed the patch somewhat
and dropped the reviewed-by because of those changes...I'm adding it
back for v7 based on this, thanks!

thanks,

Patch

diff --git a/fs/io_uring.c b/fs/io_uring.c
index 2c819c3c855d..15715eeebaec 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -3449,7 +3449,7 @@  static int io_sqe_buffer_register(struct io_ring_ctx *ctx, void __user *arg,
 
 		ret = 0;
 		down_read(&current->mm->mmap_sem);
-		pret = get_user_pages(ubuf, nr_pages,
+		pret = pin_user_pages(ubuf, nr_pages,
 				      FOLL_WRITE | FOLL_LONGTERM,
 				      pages, vmas);
 		if (pret == nr_pages) {