// SPDX-License-Identifier: GPL-2.0+
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/*
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* Copyright (C) 2017 Oracle. All Rights Reserved.
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* Author: Darrick J. Wong <darrick.wong@oracle.com>
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*/
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#include "xfs.h"
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#include "xfs_fs.h"
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#include "xfs_shared.h"
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#include "xfs_format.h"
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#include "xfs_btree.h"
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#include "xfs_rmap.h"
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#include "xfs_refcount.h"
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#include "scrub/scrub.h"
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#include "scrub/common.h"
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#include "scrub/btree.h"
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/*
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* Set us up to scrub reference count btrees.
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*/
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int
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xchk_setup_ag_refcountbt(
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struct xfs_scrub *sc,
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struct xfs_inode *ip)
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{
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return xchk_setup_ag_btree(sc, ip, false);
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}
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/* Reference count btree scrubber. */
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/*
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* Confirming Reference Counts via Reverse Mappings
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*
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* We want to count the reverse mappings overlapping a refcount record
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* (bno, len, refcount), allowing for the possibility that some of the
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* overlap may come from smaller adjoining reverse mappings, while some
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* comes from single extents which overlap the range entirely. The
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* outer loop is as follows:
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*
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* 1. For all reverse mappings overlapping the refcount extent,
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* a. If a given rmap completely overlaps, mark it as seen.
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* b. Otherwise, record the fragment (in agbno order) for later
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* processing.
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*
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* Once we've seen all the rmaps, we know that for all blocks in the
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* refcount record we want to find $refcount owners and we've already
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* visited $seen extents that overlap all the blocks. Therefore, we
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* need to find ($refcount - $seen) owners for every block in the
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* extent; call that quantity $target_nr. Proceed as follows:
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*
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* 2. Pull the first $target_nr fragments from the list; all of them
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* should start at or before the start of the extent.
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* Call this subset of fragments the working set.
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* 3. Until there are no more unprocessed fragments,
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* a. Find the shortest fragments in the set and remove them.
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* b. Note the block number of the end of these fragments.
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* c. Pull the same number of fragments from the list. All of these
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* fragments should start at the block number recorded in the
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* previous step.
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* d. Put those fragments in the set.
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* 4. Check that there are $target_nr fragments remaining in the list,
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* and that they all end at or beyond the end of the refcount extent.
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*
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* If the refcount is correct, all the check conditions in the algorithm
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* should always hold true. If not, the refcount is incorrect.
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*/
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struct xchk_refcnt_frag {
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struct list_head list;
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struct xfs_rmap_irec rm;
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};
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struct xchk_refcnt_check {
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struct xfs_scrub *sc;
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struct list_head fragments;
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/* refcount extent we're examining */
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xfs_agblock_t bno;
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xfs_extlen_t len;
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xfs_nlink_t refcount;
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/* number of owners seen */
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xfs_nlink_t seen;
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};
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/*
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* Decide if the given rmap is large enough that we can redeem it
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* towards refcount verification now, or if it's a fragment, in
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* which case we'll hang onto it in the hopes that we'll later
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* discover that we've collected exactly the correct number of
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* fragments as the refcountbt says we should have.
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*/
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STATIC int
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xchk_refcountbt_rmap_check(
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struct xfs_btree_cur *cur,
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struct xfs_rmap_irec *rec,
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void *priv)
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{
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struct xchk_refcnt_check *refchk = priv;
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struct xchk_refcnt_frag *frag;
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xfs_agblock_t rm_last;
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xfs_agblock_t rc_last;
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int error = 0;
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if (xchk_should_terminate(refchk->sc, &error))
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return error;
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rm_last = rec->rm_startblock + rec->rm_blockcount - 1;
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rc_last = refchk->bno + refchk->len - 1;
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/* Confirm that a single-owner refc extent is a CoW stage. */
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if (refchk->refcount == 1 && rec->rm_owner != XFS_RMAP_OWN_COW) {
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xchk_btree_xref_set_corrupt(refchk->sc, cur, 0);
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return 0;
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}
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if (rec->rm_startblock <= refchk->bno && rm_last >= rc_last) {
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/*
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* The rmap overlaps the refcount record, so we can confirm
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* one refcount owner seen.
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*/
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refchk->seen++;
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} else {
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/*
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* This rmap covers only part of the refcount record, so
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* save the fragment for later processing. If the rmapbt
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* is healthy each rmap_irec we see will be in agbno order
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* so we don't need insertion sort here.
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*/
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frag = kmem_alloc(sizeof(struct xchk_refcnt_frag),
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KM_MAYFAIL);
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if (!frag)
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return -ENOMEM;
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memcpy(&frag->rm, rec, sizeof(frag->rm));
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list_add_tail(&frag->list, &refchk->fragments);
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}
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return 0;
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}
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/*
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* Given a bunch of rmap fragments, iterate through them, keeping
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* a running tally of the refcount. If this ever deviates from
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* what we expect (which is the refcountbt's refcount minus the
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* number of extents that totally covered the refcountbt extent),
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* we have a refcountbt error.
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*/
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STATIC void
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xchk_refcountbt_process_rmap_fragments(
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struct xchk_refcnt_check *refchk)
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{
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struct list_head worklist;
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struct xchk_refcnt_frag *frag;
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struct xchk_refcnt_frag *n;
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xfs_agblock_t bno;
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xfs_agblock_t rbno;
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xfs_agblock_t next_rbno;
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xfs_nlink_t nr;
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xfs_nlink_t target_nr;
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target_nr = refchk->refcount - refchk->seen;
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if (target_nr == 0)
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return;
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/*
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* There are (refchk->rc.rc_refcount - refchk->nr refcount)
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* references we haven't found yet. Pull that many off the
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* fragment list and figure out where the smallest rmap ends
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* (and therefore the next rmap should start). All the rmaps
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* we pull off should start at or before the beginning of the
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* refcount record's range.
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*/
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INIT_LIST_HEAD(&worklist);
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rbno = NULLAGBLOCK;
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/* Make sure the fragments actually /are/ in agbno order. */
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bno = 0;
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list_for_each_entry(frag, &refchk->fragments, list) {
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if (frag->rm.rm_startblock < bno)
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goto done;
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bno = frag->rm.rm_startblock;
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}
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/*
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* Find all the rmaps that start at or before the refc extent,
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* and put them on the worklist.
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*/
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nr = 0;
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list_for_each_entry_safe(frag, n, &refchk->fragments, list) {
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if (frag->rm.rm_startblock > refchk->bno || nr > target_nr)
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break;
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bno = frag->rm.rm_startblock + frag->rm.rm_blockcount;
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if (bno < rbno)
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rbno = bno;
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list_move_tail(&frag->list, &worklist);
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nr++;
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}
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/*
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* We should have found exactly $target_nr rmap fragments starting
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* at or before the refcount extent.
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*/
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if (nr != target_nr)
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goto done;
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while (!list_empty(&refchk->fragments)) {
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/* Discard any fragments ending at rbno from the worklist. */
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nr = 0;
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next_rbno = NULLAGBLOCK;
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list_for_each_entry_safe(frag, n, &worklist, list) {
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bno = frag->rm.rm_startblock + frag->rm.rm_blockcount;
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if (bno != rbno) {
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if (bno < next_rbno)
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next_rbno = bno;
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continue;
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}
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list_del(&frag->list);
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kmem_free(frag);
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nr++;
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}
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/* Try to add nr rmaps starting at rbno to the worklist. */
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list_for_each_entry_safe(frag, n, &refchk->fragments, list) {
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bno = frag->rm.rm_startblock + frag->rm.rm_blockcount;
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if (frag->rm.rm_startblock != rbno)
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goto done;
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list_move_tail(&frag->list, &worklist);
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if (next_rbno > bno)
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next_rbno = bno;
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nr--;
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if (nr == 0)
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break;
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}
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/*
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* If we get here and nr > 0, this means that we added fewer
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* items to the worklist than we discarded because the fragment
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* list ran out of items. Therefore, we cannot maintain the
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* required refcount. Something is wrong, so we're done.
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*/
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if (nr)
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goto done;
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rbno = next_rbno;
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}
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/*
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* Make sure the last extent we processed ends at or beyond
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* the end of the refcount extent.
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*/
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if (rbno < refchk->bno + refchk->len)
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goto done;
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/* Actually record us having seen the remaining refcount. */
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refchk->seen = refchk->refcount;
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done:
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/* Delete fragments and work list. */
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list_for_each_entry_safe(frag, n, &worklist, list) {
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list_del(&frag->list);
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kmem_free(frag);
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}
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list_for_each_entry_safe(frag, n, &refchk->fragments, list) {
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list_del(&frag->list);
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kmem_free(frag);
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}
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}
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/* Use the rmap entries covering this extent to verify the refcount. */
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STATIC void
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xchk_refcountbt_xref_rmap(
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struct xfs_scrub *sc,
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xfs_agblock_t bno,
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xfs_extlen_t len,
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xfs_nlink_t refcount)
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{
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struct xchk_refcnt_check refchk = {
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.sc = sc,
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.bno = bno,
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.len = len,
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.refcount = refcount,
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.seen = 0,
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};
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struct xfs_rmap_irec low;
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struct xfs_rmap_irec high;
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struct xchk_refcnt_frag *frag;
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struct xchk_refcnt_frag *n;
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int error;
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if (!sc->sa.rmap_cur || xchk_skip_xref(sc->sm))
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return;
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/* Cross-reference with the rmapbt to confirm the refcount. */
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memset(&low, 0, sizeof(low));
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low.rm_startblock = bno;
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memset(&high, 0xFF, sizeof(high));
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high.rm_startblock = bno + len - 1;
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INIT_LIST_HEAD(&refchk.fragments);
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error = xfs_rmap_query_range(sc->sa.rmap_cur, &low, &high,
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&xchk_refcountbt_rmap_check, &refchk);
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if (!xchk_should_check_xref(sc, &error, &sc->sa.rmap_cur))
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goto out_free;
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xchk_refcountbt_process_rmap_fragments(&refchk);
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if (refcount != refchk.seen)
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xchk_btree_xref_set_corrupt(sc, sc->sa.rmap_cur, 0);
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out_free:
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list_for_each_entry_safe(frag, n, &refchk.fragments, list) {
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list_del(&frag->list);
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kmem_free(frag);
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}
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}
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/* Cross-reference with the other btrees. */
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STATIC void
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xchk_refcountbt_xref(
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struct xfs_scrub *sc,
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xfs_agblock_t agbno,
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xfs_extlen_t len,
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xfs_nlink_t refcount)
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{
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if (sc->sm->sm_flags & XFS_SCRUB_OFLAG_CORRUPT)
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return;
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xchk_xref_is_used_space(sc, agbno, len);
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xchk_xref_is_not_inode_chunk(sc, agbno, len);
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xchk_refcountbt_xref_rmap(sc, agbno, len, refcount);
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}
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/* Scrub a refcountbt record. */
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STATIC int
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xchk_refcountbt_rec(
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struct xchk_btree *bs,
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union xfs_btree_rec *rec)
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{
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struct xfs_mount *mp = bs->cur->bc_mp;
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xfs_agblock_t *cow_blocks = bs->private;
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xfs_agnumber_t agno = bs->cur->bc_ag.agno;
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xfs_agblock_t bno;
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xfs_extlen_t len;
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xfs_nlink_t refcount;
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bool has_cowflag;
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bno = be32_to_cpu(rec->refc.rc_startblock);
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len = be32_to_cpu(rec->refc.rc_blockcount);
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refcount = be32_to_cpu(rec->refc.rc_refcount);
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/* Only CoW records can have refcount == 1. */
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has_cowflag = (bno & XFS_REFC_COW_START);
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if ((refcount == 1 && !has_cowflag) || (refcount != 1 && has_cowflag))
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xchk_btree_set_corrupt(bs->sc, bs->cur, 0);
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if (has_cowflag)
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(*cow_blocks) += len;
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/* Check the extent. */
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bno &= ~XFS_REFC_COW_START;
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if (bno + len <= bno ||
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!xfs_verify_agbno(mp, agno, bno) ||
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!xfs_verify_agbno(mp, agno, bno + len - 1))
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xchk_btree_set_corrupt(bs->sc, bs->cur, 0);
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if (refcount == 0)
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xchk_btree_set_corrupt(bs->sc, bs->cur, 0);
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xchk_refcountbt_xref(bs->sc, bno, len, refcount);
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return 0;
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}
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/* Make sure we have as many refc blocks as the rmap says. */
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STATIC void
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xchk_refcount_xref_rmap(
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struct xfs_scrub *sc,
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xfs_filblks_t cow_blocks)
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{
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xfs_extlen_t refcbt_blocks = 0;
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xfs_filblks_t blocks;
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int error;
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if (!sc->sa.rmap_cur || xchk_skip_xref(sc->sm))
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return;
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/* Check that we saw as many refcbt blocks as the rmap knows about. */
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error = xfs_btree_count_blocks(sc->sa.refc_cur, &refcbt_blocks);
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if (!xchk_btree_process_error(sc, sc->sa.refc_cur, 0, &error))
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return;
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error = xchk_count_rmap_ownedby_ag(sc, sc->sa.rmap_cur,
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&XFS_RMAP_OINFO_REFC, &blocks);
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if (!xchk_should_check_xref(sc, &error, &sc->sa.rmap_cur))
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return;
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if (blocks != refcbt_blocks)
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xchk_btree_xref_set_corrupt(sc, sc->sa.rmap_cur, 0);
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/* Check that we saw as many cow blocks as the rmap knows about. */
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error = xchk_count_rmap_ownedby_ag(sc, sc->sa.rmap_cur,
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&XFS_RMAP_OINFO_COW, &blocks);
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if (!xchk_should_check_xref(sc, &error, &sc->sa.rmap_cur))
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return;
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if (blocks != cow_blocks)
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xchk_btree_xref_set_corrupt(sc, sc->sa.rmap_cur, 0);
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}
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/* Scrub the refcount btree for some AG. */
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int
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xchk_refcountbt(
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struct xfs_scrub *sc)
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{
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xfs_agblock_t cow_blocks = 0;
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int error;
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error = xchk_btree(sc, sc->sa.refc_cur, xchk_refcountbt_rec,
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&XFS_RMAP_OINFO_REFC, &cow_blocks);
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if (error)
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return error;
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xchk_refcount_xref_rmap(sc, cow_blocks);
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return 0;
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}
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/* xref check that a cow staging extent is marked in the refcountbt. */
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void
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xchk_xref_is_cow_staging(
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struct xfs_scrub *sc,
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xfs_agblock_t agbno,
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xfs_extlen_t len)
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{
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struct xfs_refcount_irec rc;
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bool has_cowflag;
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int has_refcount;
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int error;
|
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if (!sc->sa.refc_cur || xchk_skip_xref(sc->sm))
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return;
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/* Find the CoW staging extent. */
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error = xfs_refcount_lookup_le(sc->sa.refc_cur,
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agbno + XFS_REFC_COW_START, &has_refcount);
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if (!xchk_should_check_xref(sc, &error, &sc->sa.refc_cur))
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return;
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if (!has_refcount) {
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xchk_btree_xref_set_corrupt(sc, sc->sa.refc_cur, 0);
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return;
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}
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error = xfs_refcount_get_rec(sc->sa.refc_cur, &rc, &has_refcount);
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if (!xchk_should_check_xref(sc, &error, &sc->sa.refc_cur))
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return;
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if (!has_refcount) {
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xchk_btree_xref_set_corrupt(sc, sc->sa.refc_cur, 0);
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return;
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}
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/* CoW flag must be set, refcount must be 1. */
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has_cowflag = (rc.rc_startblock & XFS_REFC_COW_START);
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if (!has_cowflag || rc.rc_refcount != 1)
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xchk_btree_xref_set_corrupt(sc, sc->sa.refc_cur, 0);
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/* Must be at least as long as what was passed in */
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if (rc.rc_blockcount < len)
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xchk_btree_xref_set_corrupt(sc, sc->sa.refc_cur, 0);
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}
|
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/*
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* xref check that the extent is not shared. Only file data blocks
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* can have multiple owners.
|
*/
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void
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xchk_xref_is_not_shared(
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struct xfs_scrub *sc,
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xfs_agblock_t agbno,
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xfs_extlen_t len)
|
{
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bool shared;
|
int error;
|
|
if (!sc->sa.refc_cur || xchk_skip_xref(sc->sm))
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return;
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error = xfs_refcount_has_record(sc->sa.refc_cur, agbno, len, &shared);
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if (!xchk_should_check_xref(sc, &error, &sc->sa.refc_cur))
|
return;
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if (shared)
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xchk_btree_xref_set_corrupt(sc, sc->sa.refc_cur, 0);
|
}
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