Re: [RFC PATCH v4 4/5] btrfs: ioctl: introduce btrfs_uring_import_iovec()

[Sidong Yang <sidong.yang@furiosa.ai>]

On Mon, Mar 17, 2025 at 08:37:04AM -0700, Caleb Sander Mateos wrote:
> On Mon, Mar 17, 2025 at 7:00 AM Sidong Yang <sidong.yang@furiosa.ai> wrote:
> >
> > This patch introduces btrfs_uring_import_iovec(). In encoded read/write
> > with uring cmd, it uses import_iovec without supporting fixed buffer.
> > btrfs_using_import_iovec() could use fixed buffer if cmd flags has
> > IORING_URING_CMD_FIXED.
> >
> > Signed-off-by: Sidong Yang <sidong.yang@furiosa.ai>
> > ---
> >  fs/btrfs/ioctl.c | 32 ++++++++++++++++++++++++--------
> >  1 file changed, 24 insertions(+), 8 deletions(-)
> >
> > diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
> > index 6c18bad53cd3..a7b52fd99059 100644
> > --- a/fs/btrfs/ioctl.c
> > +++ b/fs/btrfs/ioctl.c
> > @@ -4802,6 +4802,28 @@ struct btrfs_uring_encoded_data {
> >         struct iov_iter iter;
> >  };
> >
> > +static int btrfs_uring_import_iovec(struct io_uring_cmd *cmd,
> > +                                   unsigned int issue_flags, int rw)
> > +{
> > +       struct btrfs_uring_encoded_data *data =
> > +               io_uring_cmd_get_async_data(cmd)->op_data;
> > +       int ret;
> > +
> > +       if (cmd && (cmd->flags & IORING_URING_CMD_FIXED)) {
> > +               data->iov = NULL;
> > +               ret = io_uring_cmd_import_fixed_vec(cmd, data->args.iov,
> > +                                                   data->args.iovcnt,
> > +                                                   ITER_DEST, issue_flags,
> 
> Why ITER_DEST instead of rw?

Oh, it's a mistake. It should be rw.

Thanks,
Sidong

> 
> Best,
> Caleb
> 
> > +                                                   &data->iter);
> > +       } else {
> > +               data->iov = data->iovstack;
> > +               ret = import_iovec(rw, data->args.iov, data->args.iovcnt,
> > +                                  ARRAY_SIZE(data->iovstack), &data->iov,
> > +                                  &data->iter);
> > +       }
> > +       return ret;
> > +}
> > +
> >  static int btrfs_uring_encoded_read(struct io_uring_cmd *cmd, unsigned int issue_flags)
> >  {
> >         size_t copy_end_kernel = offsetofend(struct btrfs_ioctl_encoded_io_args, flags);
> > @@ -4874,10 +4896,7 @@ static int btrfs_uring_encoded_read(struct io_uring_cmd *cmd, unsigned int issue
> >                         goto out_acct;
> >                 }
> >
> > -               data->iov = data->iovstack;
> > -               ret = import_iovec(ITER_DEST, data->args.iov, data->args.iovcnt,
> > -                                  ARRAY_SIZE(data->iovstack), &data->iov,
> > -                                  &data->iter);
> > +               ret = btrfs_uring_import_iovec(cmd, issue_flags, ITER_DEST);
> >                 if (ret < 0)
> >                         goto out_acct;
> >
> > @@ -5022,10 +5041,7 @@ static int btrfs_uring_encoded_write(struct io_uring_cmd *cmd, unsigned int issu
> >                 if (data->args.len > data->args.unencoded_len - data->args.unencoded_offset)
> >                         goto out_acct;
> >
> > -               data->iov = data->iovstack;
> > -               ret = import_iovec(ITER_SOURCE, data->args.iov, data->args.iovcnt,
> > -                                  ARRAY_SIZE(data->iovstack), &data->iov,
> > -                                  &data->iter);
> > +               ret = btrfs_uring_import_iovec(cmd, issue_flags, ITER_SOURCE);
> >                 if (ret < 0)
> >                         goto out_acct;
> >
> > --
> > 2.43.0
> >
> >