Re: [PATCH 31/45] xfs: CIL context doesn't need to count iovecs

Darrick J. Wong
2021-03-09T03:17:05Z

On Fri, Mar 05, 2021 at 04:11:29PM +1100, Dave Chinner wrote:
> From: Dave Chinner <dchinner@redhat.com>
>
> Now that we account for log opheaders in the log item formatting
> code, we don't actually use the aggregated count of log iovecs in
> the CIL for anything. Remove it and the tracking code that
> calculates it.
>
> Signed-off-by: Dave Chinner <dchinner@redhat.com>
> ---
> fs/xfs/xfs_log_cil.c | 22 ++++++----------------
> 1 file changed, 6 insertions(+), 16 deletions(-)
>
> diff --git a/fs/xfs/xfs_log_cil.c b/fs/xfs/xfs_log_cil.c
> index 34abc3bae587..4047f95a0fc4 100644
> --- a/fs/xfs/xfs_log_cil.c
> +++ b/fs/xfs/xfs_log_cil.c
> @@ -252,22 +252,18 @@ xlog_cil_alloc_shadow_bufs(
>
> /*
> * Prepare the log item for insertion into the CIL. Calculate the difference in
> - * log space and vectors it will consume, and if it is a new item pin it as
> - * well.
> + * log space it will consume, and if it is a new item pin it as well.
> */
> STATIC void
> xfs_cil_prepare_item(
> struct xlog *log,
> struct xfs_log_vec *lv,
> struct xfs_log_vec *old_lv,
> - int *diff_len,
> - int *diff_iovecs)
> + int *diff_len)
> {
> /* Account for the new LV being passed in */
> - if (lv->lv_buf_len != XFS_LOG_VEC_ORDERED) {
> + if (lv->lv_buf_len != XFS_LOG_VEC_ORDERED)
> *diff_len += lv->lv_bytes;
> - *diff_iovecs += lv->lv_niovecs;
> - }
>
> /*
> * If there is no old LV, this is the first time we've seen the item in
> @@ -284,7 +280,6 @@ xfs_cil_prepare_item(
> ASSERT(lv->lv_buf_len != XFS_LOG_VEC_ORDERED);
>
> *diff_len -= old_lv->lv_bytes;
> - *diff_iovecs -= old_lv->lv_niovecs;
> lv->lv_item->li_lv_shadow = old_lv;
> }
>
> @@ -333,12 +328,10 @@ static void
> xlog_cil_insert_format_items(
> struct xlog *log,
> struct xfs_trans *tp,
> - int *diff_len,
> - int *diff_iovecs)
> + int *diff_len)
> {
> struct xfs_log_item *lip;
>
> -
> /* Bail out if we didn't find a log item. */
> if (list_empty(&tp->t_items)) {
> ASSERT(0);
> @@ -381,7 +374,6 @@ xlog_cil_insert_format_items(
> * set the item up as though it is a new insertion so
> * that the space reservation accounting is correct.
> */
> - *diff_iovecs -= lv->lv_niovecs;
> *diff_len -= lv->lv_bytes;
>
> /* Ensure the lv is set up according to ->iop_size */
> @@ -406,7 +398,7 @@ xlog_cil_insert_format_items(
> ASSERT(IS_ALIGNED((unsigned long)lv->lv_buf, sizeof(uint64_t)));
> lip->li_ops->iop_format(lip, lv);
> insert:
> - xfs_cil_prepare_item(log, lv, old_lv, diff_len, diff_iovecs);
> + xfs_cil_prepare_item(log, lv, old_lv, diff_len);
> }
> }
>
> @@ -426,7 +418,6 @@ xlog_cil_insert_items(
> struct xfs_cil_ctx *ctx = cil->xc_ctx;
> struct xfs_log_item *lip;
> int len = 0;
> - int diff_iovecs = 0;
> int iclog_space;
> int iovhdr_res = 0, split_res = 0, ctx_res = 0;
>
> @@ -436,7 +427,7 @@ xlog_cil_insert_items(
> * We can do this safely because the context can't checkpoint until we
> * are done so it doesn't matter exactly how we update the CIL.
> */
> - xlog_cil_insert_format_items(log, tp, &len, &diff_iovecs);
> + xlog_cil_insert_format_items(log, tp, &len);
>
> spin_lock(&cil->xc_cil_lock);
>
> @@ -471,7 +462,6 @@ xlog_cil_insert_items(
> }
> tp->t_ticket->t_curr_res -= len;
> ctx->space_used += len;
> - ctx->nvecs += diff_iovecs;

If the tracking variable isn't necessary any more, should the field go
away from xfs_cil_ctx?

--D

>
> /*
> * If we've overrun the reservation, dump the tx details before we move
> --
> 2.28.0
>