[Devel] [PATCH VZ9] fs/fuse kio: set correct accounting weight for FIEMAP request msg.

[Alexey Kuznetsov]

Acknowledged

On Fri, May 30, 2025 at 7:41 AM Liu Kui <kui.liu at virtuozzo.com> wrote:
>
> This is an ancient bug that was never tested. For FIEMAP request,
> its iochunk.size could be much larger than the size of actual msg
> flying around. And its accounting weight should be PCS_CS_HOLE_WEIGHT,
> just like WRITE_HOLE or WRITE_ZERO, instead of its iochunk.size.
> Otherwise it'll make cs->in_flight overflow, crashing the kernel.
>
> Fixes: #ASUP-1567
> https://virtuozzo.atlassian.net/browse/ASUP-1567
>
> Signed-off-by: Liu Kui <kui.liu at virtuozzo.com>
> ---
>  fs/fuse/kio/pcs/pcs_map.c | 7 +++++--
>  1 file changed, 5 insertions(+), 2 deletions(-)
>
> diff --git a/fs/fuse/kio/pcs/pcs_map.c b/fs/fuse/kio/pcs/pcs_map.c
> index fc707c9dcb65..ce390ab5990c 100644
> --- a/fs/fuse/kio/pcs/pcs_map.c
> +++ b/fs/fuse/kio/pcs/pcs_map.c
> @@ -1450,7 +1450,8 @@ static void pcs_cs_deaccount(struct pcs_int_request *ireq, struct pcs_cs * cs, i
>         spin_lock(&cs->lock);
>         if (ireq->type == PCS_IREQ_IOCHUNK) {
>                 if (ireq->iochunk.cmd == PCS_REQ_T_WRITE_HOLE ||
> -                   ireq->iochunk.cmd == PCS_REQ_T_WRITE_ZERO)
> +                   ireq->iochunk.cmd == PCS_REQ_T_WRITE_ZERO ||
> +                       ireq->iochunk.cmd == PCS_REQ_T_FIEMAP)
>                         cost = PCS_CS_HOLE_WEIGHT;
>                 else
>                         cost = (ireq->flags & IREQ_F_RND_WEIGHT) ? 512*1024 : cong_roundup(ireq->iochunk.size);
> @@ -2063,7 +2064,9 @@ static int pcs_cslist_submit_read(struct pcs_int_request *ireq, struct pcs_cs_li
>
>                 sreq->flags &= ~(IREQ_F_RND_WEIGHT | IREQ_F_SEQ);
>                 BUG_ON(sreq->flags & IREQ_F_SEQ_READ);
> -               if (pcs_flow_sequential(sreq->iochunk.flow)) {
> +               if (ireq->iochunk.cmd != PCS_REQ_T_READ) {
> +                       weight = PCS_CS_HOLE_WEIGHT;
> +               } else if (pcs_flow_sequential(sreq->iochunk.flow)) {
>                         sreq->flags |= IREQ_F_SEQ_READ | IREQ_F_SEQ;
>                         atomic_inc(&csl->seq_read_in_flight);
>                         weight = cong_roundup(sreq->iochunk.size);
> --
> 2.39.5 (Apple Git-154)