On Thu, Jul 17, 2025 at 04:00:43PM +0530, Nirjhar Roy (IBM) wrote:
> pag_active_wq was removed in
> commit 9943b4573290
> ("xfs: remove the unused pag_active_wq field in struct xfs_perag")
> because it was not waited upon. Re-introducing this in struct xfs_group.
> This patch also replaces atomic_dec() in xfs_group_rele() with
>
> if (atomic_dec_and_test(&xg->xg_active_ref))
> wake_up(&xg->xg_active_wq);
>
> The reason for this change is that the online shrink code will wait
> for all the active references to come down to zero before actually
> starting the shrink process (only if the number of blocks that
> we are trying to remove is worth 1 or more AGs).
...and I guess this is the start of being able to remove live rtgroups
too?
> Signed-off-by: Nirjhar Roy (IBM) <nirjhar.roy.lists@xxxxxxxxx>
> ---
> fs/xfs/libxfs/xfs_group.c | 4 +++-
> fs/xfs/libxfs/xfs_group.h | 1 +
> 2 files changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/fs/xfs/libxfs/xfs_group.c b/fs/xfs/libxfs/xfs_group.c
> index e9d76bcdc820..1fe5319de338 100644
> --- a/fs/xfs/libxfs/xfs_group.c
> +++ b/fs/xfs/libxfs/xfs_group.c
> @@ -147,7 +147,8 @@ xfs_group_rele(
> struct xfs_group *xg)
> {
> trace_xfs_group_rele(xg, _RET_IP_);
> - atomic_dec(&xg->xg_active_ref);
> + if (atomic_dec_and_test(&xg->xg_active_ref))
> + wake_up(&xg->xg_active_wq);
> }
>
> void
> @@ -198,6 +199,7 @@ xfs_group_insert(
> xfs_defer_drain_init(&xg->xg_intents_drain);
>
> /* Active ref owned by mount indicates group is online. */
> + init_waitqueue_head(&xg->xg_active_wq);
> atomic_set(&xg->xg_active_ref, 1);
>
> error = xa_insert(&mp->m_groups[type].xa, index, xg, GFP_KERNEL);
> diff --git a/fs/xfs/libxfs/xfs_group.h b/fs/xfs/libxfs/xfs_group.h
> index 4423932a2313..dbef389ef838 100644
> --- a/fs/xfs/libxfs/xfs_group.h
> +++ b/fs/xfs/libxfs/xfs_group.h
> @@ -11,6 +11,7 @@ struct xfs_group {
> enum xfs_group_type xg_type;
> atomic_t xg_ref; /* passive reference count */
> atomic_t xg_active_ref; /* active reference count */
> + wait_queue_head_t xg_active_wq; /* woken active_ref falls to zero */
Nit: tab between the ^ variable and its type.
With that fixed,
Reviewed-by: "Darrick J. Wong" <djwong@xxxxxxxxxx>
--D
>
> /* Precalculated geometry info */
> uint32_t xg_block_count; /* max usable gbno */
> --
> 2.43.5
>
>
