linux/fs/xfs/scrub/dqiterate.c

// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Copyright (C) 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_bit.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"
#include "scrub/quota.h"
#include "scrub/trace.h"

/* Initialize a dquot iteration cursor. */
void
xchk_dqiter_init(
	struct xchk_dqiter	*cursor,
	struct xfs_scrub	*sc,
	xfs_dqtype_t		dqtype)
{
	cursor->sc = sc;
	cursor->bmap.br_startoff = NULLFILEOFF;
	cursor->dqtype = dqtype & XFS_DQTYPE_REC_MASK;
	cursor->quota_ip = xfs_quota_inode(sc->mp, cursor->dqtype);
	cursor->id = 0;
}

/*
 * Ensure that the cached data fork mapping for the dqiter cursor is fresh and
 * covers the dquot pointed to by the scan cursor.
 */
STATIC int
xchk_dquot_iter_revalidate_bmap(
	struct xchk_dqiter	*cursor)
{
	struct xfs_quotainfo	*qi = cursor->sc->mp->m_quotainfo;
	struct xfs_ifork	*ifp = xfs_ifork_ptr(cursor->quota_ip,
								XFS_DATA_FORK);
	xfs_fileoff_t		fileoff;
	xfs_dqid_t		this_id = cursor->id;
	int			nmaps = 1;
	int			error;

	fileoff = this_id / qi->qi_dqperchunk;

	/*
	 * If we have a mapping for cursor->id and it's still fresh, there's
	 * no need to reread the bmbt.
	 */
	if (cursor->bmap.br_startoff != NULLFILEOFF &&
	    cursor->if_seq == ifp->if_seq &&
	    cursor->bmap.br_startoff + cursor->bmap.br_blockcount > fileoff)
		return 0;

	/* Look up the data fork mapping for the dquot id of interest. */
	error = xfs_bmapi_read(cursor->quota_ip, fileoff,
			XFS_MAX_FILEOFF - fileoff, &cursor->bmap, &nmaps, 0);
	if (error)
		return error;
	if (!nmaps) {
		ASSERT(nmaps > 0);
		return -EFSCORRUPTED;
	}
	if (cursor->bmap.br_startoff > fileoff) {
		ASSERT(cursor->bmap.br_startoff == fileoff);
		return -EFSCORRUPTED;
	}

	cursor->if_seq = ifp->if_seq;
	trace_xchk_dquot_iter_revalidate_bmap(cursor, cursor->id);
	return 0;
}

/* Advance the dqiter cursor to the next non-sparse region of the quota file. */
STATIC int
xchk_dquot_iter_advance_bmap(
	struct xchk_dqiter	*cursor,
	uint64_t		*next_ondisk_id)
{
	struct xfs_quotainfo	*qi = cursor->sc->mp->m_quotainfo;
	struct xfs_ifork	*ifp = xfs_ifork_ptr(cursor->quota_ip,
								XFS_DATA_FORK);
	xfs_fileoff_t		fileoff;
	uint64_t		next_id;
	int			nmaps = 1;
	int			error;

	/* Find the dquot id for the next non-hole mapping. */
	do {
		fileoff = cursor->bmap.br_startoff + cursor->bmap.br_blockcount;
		if (fileoff > XFS_DQ_ID_MAX / qi->qi_dqperchunk) {
			/* The hole goes beyond the max dquot id, we're done */
			*next_ondisk_id = -1ULL;
			return 0;
		}

		error = xfs_bmapi_read(cursor->quota_ip, fileoff,
				XFS_MAX_FILEOFF - fileoff, &cursor->bmap,
				&nmaps, 0);
		if (error)
			return error;
		if (!nmaps) {
			/* Must have reached the end of the mappings. */
			*next_ondisk_id = -1ULL;
			return 0;
		}
		if (cursor->bmap.br_startoff > fileoff) {
			ASSERT(cursor->bmap.br_startoff == fileoff);
			return -EFSCORRUPTED;
		}
	} while (!xfs_bmap_is_real_extent(&cursor->bmap));

	next_id = cursor->bmap.br_startoff * qi->qi_dqperchunk;
	if (next_id > XFS_DQ_ID_MAX) {
		/* The hole goes beyond the max dquot id, we're done */
		*next_ondisk_id = -1ULL;
		return 0;
	}

	/* Propose jumping forward to the dquot in the next allocated block. */
	*next_ondisk_id = next_id;
	cursor->if_seq = ifp->if_seq;
	trace_xchk_dquot_iter_advance_bmap(cursor, *next_ondisk_id);
	return 0;
}

/*
 * Find the id of the next highest incore dquot.  Normally this will correspond
 * exactly with the quota file block mappings, but repair might have erased a
 * mapping because it was crosslinked; in that case, we need to re-allocate the
 * space so that we can reset q_blkno.
 */
STATIC void
xchk_dquot_iter_advance_incore(
	struct xchk_dqiter	*cursor,
	uint64_t		*next_incore_id)
{
	struct xfs_quotainfo	*qi = cursor->sc->mp->m_quotainfo;
	struct radix_tree_root	*tree = xfs_dquot_tree(qi, cursor->dqtype);
	struct xfs_dquot	*dq;
	unsigned int		nr_found;

	*next_incore_id = -1ULL;

	mutex_lock(&qi->qi_tree_lock);
	nr_found = radix_tree_gang_lookup(tree, (void **)&dq, cursor->id, 1);
	if (nr_found)
		*next_incore_id = dq->q_id;
	mutex_unlock(&qi->qi_tree_lock);

	trace_xchk_dquot_iter_advance_incore(cursor, *next_incore_id);
}

/*
 * Walk all incore dquots of this filesystem.  Caller must set *@cursorp to
 * zero before the first call, and must not hold the quota file ILOCK.
 * Returns 1 and a valid *@dqpp; 0 and *@dqpp == NULL when there are no more
 * dquots to iterate; or a negative errno.
 */
int
xchk_dquot_iter(
	struct xchk_dqiter	*cursor,
	struct xfs_dquot	**dqpp)
{
	struct xfs_mount	*mp = cursor->sc->mp;
	struct xfs_dquot	*dq = NULL;
	uint64_t		next_ondisk, next_incore = -1ULL;
	unsigned int		lock_mode;
	int			error = 0;

	if (cursor->id > XFS_DQ_ID_MAX)
		return 0;
	next_ondisk = cursor->id;

	/* Revalidate and/or advance the cursor. */
	lock_mode = xfs_ilock_data_map_shared(cursor->quota_ip);
	error = xchk_dquot_iter_revalidate_bmap(cursor);
	if (!error && !xfs_bmap_is_real_extent(&cursor->bmap))
		error = xchk_dquot_iter_advance_bmap(cursor, &next_ondisk);
	xfs_iunlock(cursor->quota_ip, lock_mode);
	if (error)
		return error;

	if (next_ondisk > cursor->id)
		xchk_dquot_iter_advance_incore(cursor, &next_incore);

	/* Pick the next dquot in the sequence and return it. */
	cursor->id = min(next_ondisk, next_incore);
	if (cursor->id > XFS_DQ_ID_MAX)
		return 0;

	trace_xchk_dquot_iter(cursor, cursor->id);

	error = xfs_qm_dqget(mp, cursor->id, cursor->dqtype, false, &dq);
	if (error)
		return error;

	cursor->id = dq->q_id + 1;
	*dqpp = dq;
	return 1;
}