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linux/fs/xfs/scrub/quota.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

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// 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_log_format.h"
#include "xfs_trans.h"
#include "xfs_inode.h"
#include "xfs_quota.h"
#include "xfs_qm.h"
#include "xfs_bmap.h"
#include "scrub/scrub.h"
#include "scrub/common.h"
/* Convert a scrub type code to a DQ flag, or return 0 if error. */
static inline xfs_dqtype_t
xchk_quota_to_dqtype(
struct xfs_scrub *sc)
{
switch (sc->sm->sm_type) {
case XFS_SCRUB_TYPE_UQUOTA:
return XFS_DQTYPE_USER;
case XFS_SCRUB_TYPE_GQUOTA:
return XFS_DQTYPE_GROUP;
case XFS_SCRUB_TYPE_PQUOTA:
return XFS_DQTYPE_PROJ;
default:
return 0;
}
}
/* Set us up to scrub a quota. */
int
xchk_setup_quota(
struct xfs_scrub *sc)
{
xfs_dqtype_t dqtype;
int error;
if (!XFS_IS_QUOTA_ON(sc->mp))
return -ENOENT;
dqtype = xchk_quota_to_dqtype(sc);
if (dqtype == 0)
return -EINVAL;
if (!xfs_this_quota_on(sc->mp, dqtype))
return -ENOENT;
if (xchk_need_intent_drain(sc))
xchk_fsgates_enable(sc, XCHK_FSGATES_DRAIN);
error = xchk_setup_fs(sc);
if (error)
return error;
sc->ip = xfs_quota_inode(sc->mp, dqtype);
xfs_ilock(sc->ip, XFS_ILOCK_EXCL);
sc->ilock_flags = XFS_ILOCK_EXCL;
return 0;
}
/* Quotas. */
struct xchk_quota_info {
struct xfs_scrub *sc;
xfs_dqid_t last_id;
};
/* Scrub the fields in an individual quota item. */
STATIC int
xchk_quota_item(
struct xfs_dquot *dq,
xfs_dqtype_t dqtype,
void *priv)
{
struct xchk_quota_info *sqi = priv;
struct xfs_scrub *sc = sqi->sc;
struct xfs_mount *mp = sc->mp;
struct xfs_quotainfo *qi = mp->m_quotainfo;
xfs_fileoff_t offset;
xfs_ino_t fs_icount;
int error = 0;
if (xchk_should_terminate(sc, &error))
return error;
/*
* Except for the root dquot, the actual dquot we got must either have
* the same or higher id as we saw before.
*/
offset = dq->q_id / qi->qi_dqperchunk;
if (dq->q_id && dq->q_id <= sqi->last_id)
xchk_fblock_set_corrupt(sc, XFS_DATA_FORK, offset);
sqi->last_id = dq->q_id;
/*
* Warn if the hard limits are larger than the fs.
* Administrators can do this, though in production this seems
* suspect, which is why we flag it for review.
*
* Complain about corruption if the soft limit is greater than
* the hard limit.
*/
if (dq->q_blk.hardlimit > mp->m_sb.sb_dblocks)
xchk_fblock_set_warning(sc, XFS_DATA_FORK, offset);
if (dq->q_blk.softlimit > dq->q_blk.hardlimit)
xchk_fblock_set_corrupt(sc, XFS_DATA_FORK, offset);
if (dq->q_ino.hardlimit > M_IGEO(mp)->maxicount)
xchk_fblock_set_warning(sc, XFS_DATA_FORK, offset);
if (dq->q_ino.softlimit > dq->q_ino.hardlimit)
xchk_fblock_set_corrupt(sc, XFS_DATA_FORK, offset);
if (dq->q_rtb.hardlimit > mp->m_sb.sb_rblocks)
xchk_fblock_set_warning(sc, XFS_DATA_FORK, offset);
if (dq->q_rtb.softlimit > dq->q_rtb.hardlimit)
xchk_fblock_set_corrupt(sc, XFS_DATA_FORK, offset);
/* Check the resource counts. */
fs_icount = percpu_counter_sum(&mp->m_icount);
/*
* Check that usage doesn't exceed physical limits. However, on
* a reflink filesystem we're allowed to exceed physical space
* if there are no quota limits.
*/
if (xfs_has_reflink(mp)) {
if (mp->m_sb.sb_dblocks < dq->q_blk.count)
xchk_fblock_set_warning(sc, XFS_DATA_FORK,
offset);
} else {
if (mp->m_sb.sb_dblocks < dq->q_blk.count)
xchk_fblock_set_corrupt(sc, XFS_DATA_FORK,
offset);
}
if (dq->q_ino.count > fs_icount || dq->q_rtb.count > mp->m_sb.sb_rblocks)
xchk_fblock_set_corrupt(sc, XFS_DATA_FORK, offset);
/*
* We can violate the hard limits if the admin suddenly sets a
* lower limit than the actual usage. However, we flag it for
* admin review.
*/
if (dq->q_id == 0)
goto out;
if (dq->q_blk.hardlimit != 0 &&
dq->q_blk.count > dq->q_blk.hardlimit)
xchk_fblock_set_warning(sc, XFS_DATA_FORK, offset);
if (dq->q_ino.hardlimit != 0 &&
dq->q_ino.count > dq->q_ino.hardlimit)
xchk_fblock_set_warning(sc, XFS_DATA_FORK, offset);
if (dq->q_rtb.hardlimit != 0 &&
dq->q_rtb.count > dq->q_rtb.hardlimit)
xchk_fblock_set_warning(sc, XFS_DATA_FORK, offset);
out:
if (sc->sm->sm_flags & XFS_SCRUB_OFLAG_CORRUPT)
return -ECANCELED;
return 0;
}
/* Check the quota's data fork. */
STATIC int
xchk_quota_data_fork(
struct xfs_scrub *sc)
{
struct xfs_bmbt_irec irec = { 0 };
struct xfs_iext_cursor icur;
struct xfs_quotainfo *qi = sc->mp->m_quotainfo;
struct xfs_ifork *ifp;
xfs_fileoff_t max_dqid_off;
int error = 0;
/* Invoke the fork scrubber. */
error = xchk_metadata_inode_forks(sc);
if (error || (sc->sm->sm_flags & XFS_SCRUB_OFLAG_CORRUPT))
return error;
/* Check for data fork problems that apply only to quota files. */
max_dqid_off = ((xfs_dqid_t)-1) / qi->qi_dqperchunk;
ifp = xfs_ifork_ptr(sc->ip, XFS_DATA_FORK);
for_each_xfs_iext(ifp, &icur, &irec) {
if (xchk_should_terminate(sc, &error))
break;
/*
* delalloc/unwritten extents or blocks mapped above the highest
* quota id shouldn't happen.
*/
if (!xfs_bmap_is_written_extent(&irec) ||
irec.br_startoff > max_dqid_off ||
irec.br_startoff + irec.br_blockcount - 1 > max_dqid_off) {
xchk_fblock_set_corrupt(sc, XFS_DATA_FORK,
irec.br_startoff);
break;
}
}
return error;
}
/* Scrub all of a quota type's items. */
int
xchk_quota(
struct xfs_scrub *sc)
{
struct xchk_quota_info sqi;
struct xfs_mount *mp = sc->mp;
struct xfs_quotainfo *qi = mp->m_quotainfo;
xfs_dqtype_t dqtype;
int error = 0;
dqtype = xchk_quota_to_dqtype(sc);
/* Look for problem extents. */
error = xchk_quota_data_fork(sc);
if (error)
goto out;
if (sc->sm->sm_flags & XFS_SCRUB_OFLAG_CORRUPT)
goto out;
/*
* Check all the quota items. Now that we've checked the quota inode
* data fork we have to drop ILOCK_EXCL to use the regular dquot
* functions.
*/
xfs_iunlock(sc->ip, sc->ilock_flags);
sc->ilock_flags = 0;
sqi.sc = sc;
sqi.last_id = 0;
error = xfs_qm_dqiterate(mp, dqtype, xchk_quota_item, &sqi);
sc->ilock_flags = XFS_ILOCK_EXCL;
xfs_ilock(sc->ip, sc->ilock_flags);
if (error == -ECANCELED)
error = 0;
if (!xchk_fblock_process_error(sc, XFS_DATA_FORK,
sqi.last_id * qi->qi_dqperchunk, &error))
goto out;
out:
return error;
}
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