On Fri, Sep 27, 2019 at 01:17:56PM -0400, Brian Foster wrote:
> The cntbt lastblock scan checks the size, alignment, locality, etc.
> of each free extent in the block and compares it with the current
> best candidate. This logic will be reused by the upcoming optimized
> cntbt algorithm, so refactor it into a separate helper. Note that
> acur->diff is now initialized to -1 (unsigned) instead of 0 to
> support the more granular comparison logic in the new helper.
>
> Signed-off-by: Brian Foster <bfoster@xxxxxxxxxx>
Looks ok,
Reviewed-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
--D
> ---
> fs/xfs/libxfs/xfs_alloc.c | 115 ++++++++++++++++++++++++++++----------
> fs/xfs/xfs_trace.h | 26 +++++++++
> 2 files changed, 113 insertions(+), 28 deletions(-)
>
> diff --git a/fs/xfs/libxfs/xfs_alloc.c b/fs/xfs/libxfs/xfs_alloc.c
> index 4514a059486e..38183953636a 100644
> --- a/fs/xfs/libxfs/xfs_alloc.c
> +++ b/fs/xfs/libxfs/xfs_alloc.c
> @@ -744,7 +744,7 @@ xfs_alloc_cur_setup(
> acur->rec_len = 0;
> acur->bno = 0;
> acur->len = 0;
> - acur->diff = 0;
> + acur->diff = -1;
> acur->busy = false;
> acur->busy_gen = 0;
>
> @@ -791,6 +791,89 @@ xfs_alloc_cur_close(
> acur->cnt = acur->bnolt = acur->bnogt = NULL;
> }
>
> +/*
> + * Check an extent for allocation and track the best available candidate in the
> + * allocation structure. The cursor is deactivated if it has entered an out of
> + * range state based on allocation arguments. Optionally return the extent
> + * extent geometry and allocation status if requested by the caller.
> + */
> +static int
> +xfs_alloc_cur_check(
> + struct xfs_alloc_arg *args,
> + struct xfs_alloc_cur *acur,
> + struct xfs_btree_cur *cur,
> + int *new)
> +{
> + int error, i;
> + xfs_agblock_t bno, bnoa, bnew;
> + xfs_extlen_t len, lena, diff = -1;
> + bool busy;
> + unsigned busy_gen = 0;
> + bool deactivate = false;
> +
> + *new = 0;
> +
> + error = xfs_alloc_get_rec(cur, &bno, &len, &i);
> + if (error)
> + return error;
> + XFS_WANT_CORRUPTED_RETURN(args->mp, i == 1);
> +
> + /*
> + * Check minlen and deactivate a cntbt cursor if out of acceptable size
> + * range (i.e., walking backwards looking for a minlen extent).
> + */
> + if (len < args->minlen) {
> + deactivate = true;
> + goto out;
> + }
> +
> + busy = xfs_alloc_compute_aligned(args, bno, len, &bnoa, &lena,
> + &busy_gen);
> + acur->busy |= busy;
> + if (busy)
> + acur->busy_gen = busy_gen;
> + /* deactivate a bnobt cursor outside of locality range */
> + if (bnoa < args->min_agbno || bnoa > args->max_agbno)
> + goto out;
> + if (lena < args->minlen)
> + goto out;
> +
> + args->len = XFS_EXTLEN_MIN(lena, args->maxlen);
> + xfs_alloc_fix_len(args);
> + ASSERT(args->len >= args->minlen);
> + if (args->len < acur->len)
> + goto out;
> +
> + /*
> + * We have an aligned record that satisfies minlen and beats or matches
> + * the candidate extent size. Compare locality for near allocation mode.
> + */
> + ASSERT(args->type == XFS_ALLOCTYPE_NEAR_BNO);
> + diff = xfs_alloc_compute_diff(args->agbno, args->len,
> + args->alignment, args->datatype,
> + bnoa, lena, &bnew);
> + if (bnew == NULLAGBLOCK)
> + goto out;
> + if (diff > acur->diff)
> + goto out;
> +
> + ASSERT(args->len > acur->len ||
> + (args->len == acur->len && diff <= acur->diff));
> + acur->rec_bno = bno;
> + acur->rec_len = len;
> + acur->bno = bnew;
> + acur->len = args->len;
> + acur->diff = diff;
> + *new = 1;
> +
> +out:
> + if (deactivate)
> + cur->bc_private.a.priv.abt.active = false;
> + trace_xfs_alloc_cur_check(args->mp, cur->bc_btnum, bno, len, diff,
> + *new);
> + return 0;
> +}
> +
> /*
> * Deal with the case where only small freespaces remain. Either return the
> * contents of the last freespace record, or allocate space from the freelist if
> @@ -1257,8 +1340,6 @@ xfs_alloc_ag_vextent_near(
> * but we never loop back to the top.
> */
> while (xfs_btree_islastblock(acur.cnt, 0)) {
> - xfs_extlen_t diff;
> -
> #ifdef DEBUG
> if (dofirst)
> break;
> @@ -1289,38 +1370,16 @@ xfs_alloc_ag_vextent_near(
> }
> i = acur.cnt->bc_ptrs[0];
> for (j = 1;
> - !error && j && (acur.len < args->maxlen || acur.diff > 0);
> + !error && j && xfs_alloc_cur_active(acur.cnt) &&
> + (acur.len < args->maxlen || acur.diff > 0);
> error = xfs_btree_increment(acur.cnt, 0, &j)) {
> /*
> * For each entry, decide if it's better than
> * the previous best entry.
> */
> - error = xfs_alloc_get_rec(acur.cnt, <bno, <len, &i);
> + error = xfs_alloc_cur_check(args, &acur, acur.cnt, &i);
> if (error)
> goto out;
> - XFS_WANT_CORRUPTED_GOTO(args->mp, i == 1, out);
> - acur.busy = xfs_alloc_compute_aligned(args, ltbno, ltlen,
> - <bnoa, <lena, &acur.busy_gen);
> - if (ltlena < args->minlen)
> - continue;
> - if (ltbnoa < args->min_agbno || ltbnoa > args->max_agbno)
> - continue;
> - args->len = XFS_EXTLEN_MIN(ltlena, args->maxlen);
> - xfs_alloc_fix_len(args);
> - ASSERT(args->len >= args->minlen);
> - if (args->len < acur.len)
> - continue;
> - diff = xfs_alloc_compute_diff(args->agbno, args->len,
> - args->alignment, args->datatype, ltbnoa,
> - ltlena, <new);
> - if (ltnew != NULLAGBLOCK &&
> - (args->len > acur.len || diff < acur.diff)) {
> - acur.rec_bno = ltbno;
> - acur.rec_len = ltlen;
> - acur.diff = diff;
> - acur.bno = ltnew;
> - acur.len = args->len;
> - }
> }
> /*
> * It didn't work. We COULD be in a case where
> diff --git a/fs/xfs/xfs_trace.h b/fs/xfs/xfs_trace.h
> index eaae275ed430..cf618919cacf 100644
> --- a/fs/xfs/xfs_trace.h
> +++ b/fs/xfs/xfs_trace.h
> @@ -1663,6 +1663,32 @@ DEFINE_ALLOC_EVENT(xfs_alloc_vextent_noagbp);
> DEFINE_ALLOC_EVENT(xfs_alloc_vextent_loopfailed);
> DEFINE_ALLOC_EVENT(xfs_alloc_vextent_allfailed);
>
> +TRACE_EVENT(xfs_alloc_cur_check,
> + TP_PROTO(struct xfs_mount *mp, xfs_btnum_t btnum, xfs_agblock_t bno,
> + xfs_extlen_t len, xfs_extlen_t diff, bool new),
> + TP_ARGS(mp, btnum, bno, len, diff, new),
> + TP_STRUCT__entry(
> + __field(dev_t, dev)
> + __field(xfs_btnum_t, btnum)
> + __field(xfs_agblock_t, bno)
> + __field(xfs_extlen_t, len)
> + __field(xfs_extlen_t, diff)
> + __field(bool, new)
> + ),
> + TP_fast_assign(
> + __entry->dev = mp->m_super->s_dev;
> + __entry->btnum = btnum;
> + __entry->bno = bno;
> + __entry->len = len;
> + __entry->diff = diff;
> + __entry->new = new;
> + ),
> + TP_printk("dev %d:%d btree %s bno 0x%x len 0x%x diff 0x%x new %d",
> + MAJOR(__entry->dev), MINOR(__entry->dev),
> + __print_symbolic(__entry->btnum, XFS_BTNUM_STRINGS),
> + __entry->bno, __entry->len, __entry->diff, __entry->new)
> +)
> +
> DECLARE_EVENT_CLASS(xfs_da_class,
> TP_PROTO(struct xfs_da_args *args),
> TP_ARGS(args),
> --
> 2.20.1
>
