On Wed, Nov 25 2015 at 4:03pm -0500,
Mikulas Patocka <mpatocka@xxxxxxxxxx> wrote:
> Device mapper used the field bi_private to point to dm_target_io. However,
> since kernel 3.15, the bi_private field is unused, and so the targets do
> not need to save and restore this field.
>
> This patch removes code that saves and restores bi_private from dm-cache,
> dm-snapshot and dm-verity.
>
> Signed-off-by: Mikulas Patocka <mpatocka@xxxxxxxxxx>
>
> ---
> drivers/md/dm-cache-target.c | 3 ---
> drivers/md/dm-snap.c | 6 +-----
> drivers/md/dm-verity.c | 3 ---
> 3 files changed, 1 insertion(+), 11 deletions(-)
>
> Index: linux-4.4-rc2/drivers/md/dm-cache-target.c
> ===================================================================
> --- linux-4.4-rc2.orig/drivers/md/dm-cache-target.c 2015-11-24 15:33:56.000000000 +0100
> +++ linux-4.4-rc2/drivers/md/dm-cache-target.c 2015-11-24 15:34:35.000000000 +0100
> @@ -118,14 +118,12 @@ static void iot_io_end(struct io_tracker
> */
> struct dm_hook_info {
> bio_end_io_t *bi_end_io;
> - void *bi_private;
> };
>
> static void dm_hook_bio(struct dm_hook_info *h, struct bio *bio,
> bio_end_io_t *bi_end_io, void *bi_private)
> {
> h->bi_end_io = bio->bi_end_io;
> - h->bi_private = bio->bi_private;
>
> bio->bi_end_io = bi_end_io;
> bio->bi_private = bi_private;
As you can see dm_hook_bio() goes on to modify bi_private.
dm-cache uses it to get the migration object associated with a bio for
the overwrite_endio() case.
So NAK on the dm-cache change.
How closely have you reviewed your change for snapshot and verity?
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