btrfs extent_state.private compiler warning (Re: Btrfs: cleanup the read failure record after write or when the inode is freeing)

[Geert Uytterhoeven]

On Sat, Oct 11, 2014 at 2:08 PM, Linux Kernel Mailing List
<linux-kernel@xxxxxxxxxxxxxxx> wrote:
> Gitweb:     http://git.kernel.org/linus/;a=commit;h=f612496bca664bff6a09a99a9a7506410b6e876e
> Commit:     f612496bca664bff6a09a99a9a7506410b6e876e

>     Btrfs: cleanup the read failure record after write or when the inode is freeing
>
>     After the data is written successfully, we should cleanup the read failure record
>     in that range because
>     - If we set data COW for the file, the range that the failure record pointed to is
>       mapped to a new place, so it is invalid.
>     - If we set no data COW for the file, and if there is no error during writting,
>       the corrupted data is corrected, so the failure record can be removed. And if
>       some errors happen on the mirrors, we also needn't worry about it because the
>       failure record will be recreated if we read the same place again.
>
>     Sometimes, we may fail to correct the data, so the failure records will be left
>     in the tree, we need free them when we free the inode or the memory leak happens.

> --- a/fs/btrfs/extent_io.c
> +++ b/fs/btrfs/extent_io.c

> +void btrfs_free_io_failure_record(struct inode *inode, u64 start, u64 end)
> +{
> +       struct extent_io_tree *failure_tree = &BTRFS_I(inode)->io_failure_tree;
> +       struct io_failure_record *failrec;
> +       struct extent_state *state, *next;

> +               failrec = (struct io_failure_record *)state->private;

On 32-bit:

fs/btrfs/extent_io.c: In function âbtrfs_free_io_failure_recordâ:
fs/btrfs/extent_io.c:2166: warning: cast to pointer from integer of
different size

Is there any specific reason extend_state.private is "u64", and not
"unsigned long", or better "void *", or even better
"struct io_failure_record *"?

That would get rid of the (double) cast tricks.

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds
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