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485 lines
13 KiB
485 lines
13 KiB
// 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 <[email protected]> |
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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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#include "xfs_trans_resv.h" |
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#include "xfs_mount.h" |
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#include "xfs_ag.h" |
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|
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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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{ |
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return xchk_setup_ag_btree(sc, false); |
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} |
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|
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/* Reference count btree scrubber. */ |
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|
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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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|
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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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|
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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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/* |
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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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const 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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|
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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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|
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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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/* |
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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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|
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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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|
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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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const union xfs_btree_rec *rec) |
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{ |
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xfs_agblock_t *cow_blocks = bs->private; |
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struct xfs_perag *pag = bs->cur->bc_ag.pag; |
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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(pag, bno) || |
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!xfs_verify_agbno(pag, 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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|
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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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|
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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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|
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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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*/ |
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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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{ |
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bool shared; |
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int error; |
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|
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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)) |
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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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}
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