mirror_ubuntu-kernels/fs/xfs/scrub/alloc.c
Darrick J. Wong 466c525d6d xfs: minimize overhead of drain wakeups by using jump labels
To reduce the runtime overhead even further when online fsck isn't
running, use a static branch key to decide if we call wake_up on the
drain.  For compilers that support jump labels, the call to wake_up is
replaced by a nop sled when nobody is waiting for intents to drain.

From my initial microbenchmarking, every transition of the static key
between the on and off states takes about 22000ns to complete; this is
paid entirely by the xfs_scrub process.  When the static key is off
(which it should be when fsck isn't running), the nop sled adds an
overhead of approximately 0.36ns to runtime code.  The post-atomic
lockless waiter check adds about 0.03ns, which is basically free.

For the few compilers that don't support jump labels, runtime code pays
the cost of calling wake_up on an empty waitqueue, which was observed to
be about 30ns.  However, most architectures that have sufficient memory
and CPU capacity to run XFS also support jump labels, so this is not
much of a worry.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
2023-04-11 18:59:59 -07:00

159 lines
3.3 KiB
C

// SPDX-License-Identifier: GPL-2.0-or-later
/*
* Copyright (C) 2017-2023 Oracle. All Rights Reserved.
* Author: Darrick J. Wong <djwong@kernel.org>
*/
#include "xfs.h"
#include "xfs_fs.h"
#include "xfs_shared.h"
#include "xfs_format.h"
#include "xfs_trans_resv.h"
#include "xfs_mount.h"
#include "xfs_btree.h"
#include "xfs_alloc.h"
#include "xfs_rmap.h"
#include "scrub/scrub.h"
#include "scrub/common.h"
#include "scrub/btree.h"
#include "xfs_ag.h"
/*
* Set us up to scrub free space btrees.
*/
int
xchk_setup_ag_allocbt(
struct xfs_scrub *sc)
{
if (xchk_need_intent_drain(sc))
xchk_fsgates_enable(sc, XCHK_FSGATES_DRAIN);
return xchk_setup_ag_btree(sc, false);
}
/* Free space btree scrubber. */
/*
* Ensure there's a corresponding cntbt/bnobt record matching this
* bnobt/cntbt record, respectively.
*/
STATIC void
xchk_allocbt_xref_other(
struct xfs_scrub *sc,
xfs_agblock_t agbno,
xfs_extlen_t len)
{
struct xfs_btree_cur **pcur;
xfs_agblock_t fbno;
xfs_extlen_t flen;
int has_otherrec;
int error;
if (sc->sm->sm_type == XFS_SCRUB_TYPE_BNOBT)
pcur = &sc->sa.cnt_cur;
else
pcur = &sc->sa.bno_cur;
if (!*pcur || xchk_skip_xref(sc->sm))
return;
error = xfs_alloc_lookup_le(*pcur, agbno, len, &has_otherrec);
if (!xchk_should_check_xref(sc, &error, pcur))
return;
if (!has_otherrec) {
xchk_btree_xref_set_corrupt(sc, *pcur, 0);
return;
}
error = xfs_alloc_get_rec(*pcur, &fbno, &flen, &has_otherrec);
if (!xchk_should_check_xref(sc, &error, pcur))
return;
if (!has_otherrec) {
xchk_btree_xref_set_corrupt(sc, *pcur, 0);
return;
}
if (fbno != agbno || flen != len)
xchk_btree_xref_set_corrupt(sc, *pcur, 0);
}
/* Cross-reference with the other btrees. */
STATIC void
xchk_allocbt_xref(
struct xfs_scrub *sc,
xfs_agblock_t agbno,
xfs_extlen_t len)
{
if (sc->sm->sm_flags & XFS_SCRUB_OFLAG_CORRUPT)
return;
xchk_allocbt_xref_other(sc, agbno, len);
xchk_xref_is_not_inode_chunk(sc, agbno, len);
xchk_xref_has_no_owner(sc, agbno, len);
xchk_xref_is_not_shared(sc, agbno, len);
}
/* Scrub a bnobt/cntbt record. */
STATIC int
xchk_allocbt_rec(
struct xchk_btree *bs,
const union xfs_btree_rec *rec)
{
struct xfs_perag *pag = bs->cur->bc_ag.pag;
xfs_agblock_t bno;
xfs_extlen_t len;
bno = be32_to_cpu(rec->alloc.ar_startblock);
len = be32_to_cpu(rec->alloc.ar_blockcount);
if (!xfs_verify_agbext(pag, bno, len))
xchk_btree_set_corrupt(bs->sc, bs->cur, 0);
xchk_allocbt_xref(bs->sc, bno, len);
return 0;
}
/* Scrub the freespace btrees for some AG. */
STATIC int
xchk_allocbt(
struct xfs_scrub *sc,
xfs_btnum_t which)
{
struct xfs_btree_cur *cur;
cur = which == XFS_BTNUM_BNO ? sc->sa.bno_cur : sc->sa.cnt_cur;
return xchk_btree(sc, cur, xchk_allocbt_rec, &XFS_RMAP_OINFO_AG, NULL);
}
int
xchk_bnobt(
struct xfs_scrub *sc)
{
return xchk_allocbt(sc, XFS_BTNUM_BNO);
}
int
xchk_cntbt(
struct xfs_scrub *sc)
{
return xchk_allocbt(sc, XFS_BTNUM_CNT);
}
/* xref check that the extent is not free */
void
xchk_xref_is_used_space(
struct xfs_scrub *sc,
xfs_agblock_t agbno,
xfs_extlen_t len)
{
bool is_freesp;
int error;
if (!sc->sa.bno_cur || xchk_skip_xref(sc->sm))
return;
error = xfs_alloc_has_record(sc->sa.bno_cur, agbno, len, &is_freesp);
if (!xchk_should_check_xref(sc, &error, &sc->sa.bno_cur))
return;
if (is_freesp)
xchk_btree_xref_set_corrupt(sc, sc->sa.bno_cur, 0);
}