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diff --git a/fs/xfs/scrub/repair.c b/fs/xfs/scrub/repair.c
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+/*
+ * Copyright (C) 2018 Oracle. All Rights Reserved.
+ *
+ * Author: Darrick J. Wong <darrick.wong@oracle.com>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it would be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA.
+ */
+#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_defer.h"
+#include "xfs_btree.h"
+#include "xfs_bit.h"
+#include "xfs_log_format.h"
+#include "xfs_trans.h"
+#include "xfs_sb.h"
+#include "xfs_inode.h"
+#include "xfs_icache.h"
+#include "xfs_alloc.h"
+#include "xfs_alloc_btree.h"
+#include "xfs_ialloc.h"
+#include "xfs_ialloc_btree.h"
+#include "xfs_rmap.h"
+#include "xfs_rmap_btree.h"
+#include "xfs_refcount.h"
+#include "xfs_refcount_btree.h"
+#include "xfs_extent_busy.h"
+#include "xfs_ag_resv.h"
+#include "xfs_trans_space.h"
+#include "xfs_quota.h"
+#include "scrub/xfs_scrub.h"
+#include "scrub/scrub.h"
+#include "scrub/common.h"
+#include "scrub/trace.h"
+#include "scrub/repair.h"
+
+/*
+ * Attempt to repair some metadata, if the metadata is corrupt and userspace
+ * told us to fix it. This function returns -EAGAIN to mean "re-run scrub",
+ * and will set *fixed to true if it thinks it repaired anything.
+ */
+int
+xfs_repair_attempt(
+ struct xfs_inode *ip,
+ struct xfs_scrub_context *sc,
+ bool *fixed)
+{
+ int error = 0;
+
+ trace_xfs_repair_attempt(ip, sc->sm, error);
+
+ xfs_scrub_ag_btcur_free(&sc->sa);
+
+ /* Repair whatever's broken. */
+ ASSERT(sc->ops->repair);
+ error = sc->ops->repair(sc);
+ trace_xfs_repair_done(ip, sc->sm, error);
+ switch (error) {
+ case 0:
+ /*
+ * Repair succeeded. Commit the fixes and perform a second
+ * scrub so that we can tell userspace if we fixed the problem.
+ */
+ sc->sm->sm_flags &= ~XFS_SCRUB_FLAGS_OUT;
+ *fixed = true;
+ return -EAGAIN;
+ case -EDEADLOCK:
+ case -EAGAIN:
+ /* Tell the caller to try again having grabbed all the locks. */
+ if (!sc->try_harder) {
+ sc->try_harder = true;
+ return -EAGAIN;
+ }
+ /*
+ * We tried harder but still couldn't grab all the resources
+ * we needed to fix it. The corruption has not been fixed,
+ * so report back to userspace.
+ */
+ return -EFSCORRUPTED;
+ default:
+ return error;
+ }
+}
+
+/*
+ * Complain about unfixable problems in the filesystem. We don't log
+ * corruptions when IFLAG_REPAIR wasn't set on the assumption that the driver
+ * program is xfs_scrub, which will call back with IFLAG_REPAIR set if the
+ * administrator isn't running xfs_scrub in no-repairs mode.
+ *
+ * Use this helper function because _ratelimited silently declares a static
+ * structure to track rate limiting information.
+ */
+void
+xfs_repair_failure(
+ struct xfs_mount *mp)
+{
+ xfs_alert_ratelimited(mp,
+"Corruption not fixed during online repair. Unmount and run xfs_repair.");
+}
+
+/*
+ * Repair probe -- userspace uses this to probe if we're willing to repair a
+ * given mountpoint.
+ */
+int
+xfs_repair_probe(
+ struct xfs_scrub_context *sc)
+{
+ int error = 0;
+
+ if (xfs_scrub_should_terminate(sc, &error))
+ return error;
+
+ return 0;
+}
+
+/*
+ * Roll a transaction, keeping the AG headers locked and reinitializing
+ * the btree cursors.
+ */
+int
+xfs_repair_roll_ag_trans(
+ struct xfs_scrub_context *sc)
+{
+ int error;
+
+ /* Keep the AG header buffers locked so we can keep going. */
+ xfs_trans_bhold(sc->tp, sc->sa.agi_bp);
+ xfs_trans_bhold(sc->tp, sc->sa.agf_bp);
+ xfs_trans_bhold(sc->tp, sc->sa.agfl_bp);
+
+ /* Roll the transaction. */
+ error = xfs_trans_roll(&sc->tp);
+ if (error)
+ goto out_release;
+
+ /* Join AG headers to the new transaction. */
+ xfs_trans_bjoin(sc->tp, sc->sa.agi_bp);
+ xfs_trans_bjoin(sc->tp, sc->sa.agf_bp);
+ xfs_trans_bjoin(sc->tp, sc->sa.agfl_bp);
+
+ return 0;
+
+out_release:
+ /*
+ * Rolling failed, so release the hold on the buffers. The
+ * buffers will be released during teardown on our way out
+ * of the kernel.
+ */
+ xfs_trans_bhold_release(sc->tp, sc->sa.agi_bp);
+ xfs_trans_bhold_release(sc->tp, sc->sa.agf_bp);
+ xfs_trans_bhold_release(sc->tp, sc->sa.agfl_bp);
+
+ return error;
+}
+
+/*
+ * Does the given AG have enough space to rebuild a btree? Neither AG
+ * reservation can be critical, and we must have enough space (factoring
+ * in AG reservations) to construct a whole btree.
+ */
+bool
+xfs_repair_ag_has_space(
+ struct xfs_perag *pag,
+ xfs_extlen_t nr_blocks,
+ enum xfs_ag_resv_type type)
+{
+ return !xfs_ag_resv_critical(pag, XFS_AG_RESV_RMAPBT) &&
+ !xfs_ag_resv_critical(pag, XFS_AG_RESV_METADATA) &&
+ pag->pagf_freeblks > xfs_ag_resv_needed(pag, type) + nr_blocks;
+}
+
+/*
+ * Figure out how many blocks to reserve for an AG repair. We calculate the
+ * worst case estimate for the number of blocks we'd need to rebuild one of
+ * any type of per-AG btree.
+ */
+xfs_extlen_t
+xfs_repair_calc_ag_resblks(
+ struct xfs_scrub_context *sc)
+{
+ struct xfs_mount *mp = sc->mp;
+ struct xfs_scrub_metadata *sm = sc->sm;
+ struct xfs_perag *pag;
+ struct xfs_buf *bp;
+ xfs_agino_t icount = 0;
+ xfs_extlen_t aglen = 0;
+ xfs_extlen_t usedlen;
+ xfs_extlen_t freelen;
+ xfs_extlen_t bnobt_sz;
+ xfs_extlen_t inobt_sz;
+ xfs_extlen_t rmapbt_sz;
+ xfs_extlen_t refcbt_sz;
+ int error;
+
+ if (!(sm->sm_flags & XFS_SCRUB_IFLAG_REPAIR))
+ return 0;
+
+ /* Use in-core counters if possible. */
+ pag = xfs_perag_get(mp, sm->sm_agno);
+ if (pag->pagi_init)
+ icount = pag->pagi_count;
+
+ /*
+ * Otherwise try to get the actual counters from disk; if not, make
+ * some worst case assumptions.
+ */
+ if (icount == 0) {
+ error = xfs_ialloc_read_agi(mp, NULL, sm->sm_agno, &bp);
+ if (error) {
+ icount = mp->m_sb.sb_agblocks / mp->m_sb.sb_inopblock;
+ } else {
+ icount = pag->pagi_count;
+ xfs_buf_relse(bp);
+ }
+ }
+
+ /* Now grab the block counters from the AGF. */
+ error = xfs_alloc_read_agf(mp, NULL, sm->sm_agno, 0, &bp);
+ if (error) {
+ aglen = mp->m_sb.sb_agblocks;
+ freelen = aglen;
+ usedlen = aglen;
+ } else {
+ aglen = be32_to_cpu(XFS_BUF_TO_AGF(bp)->agf_length);
+ freelen = pag->pagf_freeblks;
+ usedlen = aglen - freelen;
+ xfs_buf_relse(bp);
+ }
+ xfs_perag_put(pag);
+
+ trace_xfs_repair_calc_ag_resblks(mp, sm->sm_agno, icount, aglen,
+ freelen, usedlen);
+
+ /*
+ * Figure out how many blocks we'd need worst case to rebuild
+ * each type of btree. Note that we can only rebuild the
+ * bnobt/cntbt or inobt/finobt as pairs.
+ */
+ bnobt_sz = 2 * xfs_allocbt_calc_size(mp, freelen);
+ if (xfs_sb_version_hassparseinodes(&mp->m_sb))
+ inobt_sz = xfs_iallocbt_calc_size(mp, icount /
+ XFS_INODES_PER_HOLEMASK_BIT);
+ else
+ inobt_sz = xfs_iallocbt_calc_size(mp, icount /
+ XFS_INODES_PER_CHUNK);
+ if (xfs_sb_version_hasfinobt(&mp->m_sb))
+ inobt_sz *= 2;
+ if (xfs_sb_version_hasreflink(&mp->m_sb))
+ refcbt_sz = xfs_refcountbt_calc_size(mp, usedlen);
+ else
+ refcbt_sz = 0;
+ if (xfs_sb_version_hasrmapbt(&mp->m_sb)) {
+ /*
+ * Guess how many blocks we need to rebuild the rmapbt.
+ * For non-reflink filesystems we can't have more records than
+ * used blocks. However, with reflink it's possible to have
+ * more than one rmap record per AG block. We don't know how
+ * many rmaps there could be in the AG, so we start off with
+ * what we hope is an generous over-estimation.
+ */
+ if (xfs_sb_version_hasreflink(&mp->m_sb))
+ rmapbt_sz = xfs_rmapbt_calc_size(mp,
+ (unsigned long long)aglen * 2);
+ else
+ rmapbt_sz = xfs_rmapbt_calc_size(mp, usedlen);
+ } else {
+ rmapbt_sz = 0;
+ }
+
+ trace_xfs_repair_calc_ag_resblks_btsize(mp, sm->sm_agno, bnobt_sz,
+ inobt_sz, rmapbt_sz, refcbt_sz);
+
+ return max(max(bnobt_sz, inobt_sz), max(rmapbt_sz, refcbt_sz));
+}
+
+/* Allocate a block in an AG. */
+int
+xfs_repair_alloc_ag_block(
+ struct xfs_scrub_context *sc,
+ struct xfs_owner_info *oinfo,
+ xfs_fsblock_t *fsbno,
+ enum xfs_ag_resv_type resv)
+{
+ struct xfs_alloc_arg args = {0};
+ xfs_agblock_t bno;
+ int error;
+
+ switch (resv) {
+ case XFS_AG_RESV_AGFL:
+ case XFS_AG_RESV_RMAPBT:
+ error = xfs_alloc_get_freelist(sc->tp, sc->sa.agf_bp, &bno, 1);
+ if (error)
+ return error;
+ if (bno == NULLAGBLOCK)
+ return -ENOSPC;
+ xfs_extent_busy_reuse(sc->mp, sc->sa.agno, bno,
+ 1, false);
+ *fsbno = XFS_AGB_TO_FSB(sc->mp, sc->sa.agno, bno);
+ if (resv == XFS_AG_RESV_RMAPBT)
+ xfs_ag_resv_rmapbt_alloc(sc->mp, sc->sa.agno);
+ return 0;
+ default:
+ break;
+ }
+
+ args.tp = sc->tp;
+ args.mp = sc->mp;
+ args.oinfo = *oinfo;
+ args.fsbno = XFS_AGB_TO_FSB(args.mp, sc->sa.agno, 0);
+ args.minlen = 1;
+ args.maxlen = 1;
+ args.prod = 1;
+ args.type = XFS_ALLOCTYPE_THIS_AG;
+ args.resv = resv;
+
+ error = xfs_alloc_vextent(&args);
+ if (error)
+ return error;
+ if (args.fsbno == NULLFSBLOCK)
+ return -ENOSPC;
+ ASSERT(args.len == 1);
+ *fsbno = args.fsbno;
+
+ return 0;
+}
+
+/* Initialize a new AG btree root block with zero entries. */
+int
+xfs_repair_init_btblock(
+ struct xfs_scrub_context *sc,
+ xfs_fsblock_t fsb,
+ struct xfs_buf **bpp,
+ xfs_btnum_t btnum,
+ const struct xfs_buf_ops *ops)
+{
+ struct xfs_trans *tp = sc->tp;
+ struct xfs_mount *mp = sc->mp;
+ struct xfs_buf *bp;
+
+ trace_xfs_repair_init_btblock(mp, XFS_FSB_TO_AGNO(mp, fsb),
+ XFS_FSB_TO_AGBNO(mp, fsb), btnum);
+
+ ASSERT(XFS_FSB_TO_AGNO(mp, fsb) == sc->sa.agno);
+ bp = xfs_trans_get_buf(tp, mp->m_ddev_targp, XFS_FSB_TO_DADDR(mp, fsb),
+ XFS_FSB_TO_BB(mp, 1), 0);
+ xfs_buf_zero(bp, 0, BBTOB(bp->b_length));
+ xfs_btree_init_block(mp, bp, btnum, 0, 0, sc->sa.agno, 0);
+ xfs_trans_buf_set_type(tp, bp, XFS_BLFT_BTREE_BUF);
+ xfs_trans_log_buf(tp, bp, 0, bp->b_length);
+ bp->b_ops = ops;
+ *bpp = bp;
+
+ return 0;
+}
+
+/*
+ * Reconstructing per-AG Btrees
+ *
+ * When a space btree is corrupt, we don't bother trying to fix it. Instead,
+ * we scan secondary space metadata to derive the records that should be in
+ * the damaged btree, initialize a fresh btree root, and insert the records.
+ * Note that for rebuilding the rmapbt we scan all the primary data to
+ * generate the new records.
+ *
+ * However, that leaves the matter of removing all the metadata describing the
+ * old broken structure. For primary metadata we use the rmap data to collect
+ * every extent with a matching rmap owner (exlist); we then iterate all other
+ * metadata structures with the same rmap owner to collect the extents that
+ * cannot be removed (sublist). We then subtract sublist from exlist to
+ * derive the blocks that were used by the old btree. These blocks can be
+ * reaped.
+ *
+ * For rmapbt reconstructions we must use different tactics for extent
+ * collection. First we iterate all primary metadata (this excludes the old
+ * rmapbt, obviously) to generate new rmap records. The gaps in the rmap
+ * records are collected as exlist. The bnobt records are collected as
+ * sublist. As with the other btrees we subtract sublist from exlist, and the
+ * result (since the rmapbt lives in the free space) are the blocks from the
+ * old rmapbt.
+ */
+
+/* Collect a dead btree extent for later disposal. */
+int
+xfs_repair_collect_btree_extent(
+ struct xfs_scrub_context *sc,
+ struct xfs_repair_extent_list *exlist,
+ xfs_fsblock_t fsbno,
+ xfs_extlen_t len)
+{
+ struct xfs_repair_extent *rex;
+
+ trace_xfs_repair_collect_btree_extent(sc->mp,
+ XFS_FSB_TO_AGNO(sc->mp, fsbno),
+ XFS_FSB_TO_AGBNO(sc->mp, fsbno), len);
+
+ rex = kmem_alloc(sizeof(struct xfs_repair_extent), KM_MAYFAIL);
+ if (!rex)
+ return -ENOMEM;
+
+ INIT_LIST_HEAD(&rex->list);
+ rex->fsbno = fsbno;
+ rex->len = len;
+ list_add_tail(&rex->list, &exlist->list);
+
+ return 0;
+}
+
+/*
+ * An error happened during the rebuild so the transaction will be cancelled.
+ * The fs will shut down, and the administrator has to unmount and run repair.
+ * Therefore, free all the memory associated with the list so we can die.
+ */
+void
+xfs_repair_cancel_btree_extents(
+ struct xfs_scrub_context *sc,
+ struct xfs_repair_extent_list *exlist)
+{
+ struct xfs_repair_extent *rex;
+ struct xfs_repair_extent *n;
+
+ for_each_xfs_repair_extent_safe(rex, n, exlist) {
+ list_del(&rex->list);
+ kmem_free(rex);
+ }
+}
+
+/* Compare two btree extents. */
+static int
+xfs_repair_btree_extent_cmp(
+ void *priv,
+ struct list_head *a,
+ struct list_head *b)
+{
+ struct xfs_repair_extent *ap;
+ struct xfs_repair_extent *bp;
+
+ ap = container_of(a, struct xfs_repair_extent, list);
+ bp = container_of(b, struct xfs_repair_extent, list);
+
+ if (ap->fsbno > bp->fsbno)
+ return 1;
+ if (ap->fsbno < bp->fsbno)
+ return -1;
+ return 0;
+}
+
+/*
+ * Remove all the blocks mentioned in @sublist from the extents in @exlist.
+ *
+ * The intent is that callers will iterate the rmapbt for all of its records
+ * for a given owner to generate @exlist; and iterate all the blocks of the
+ * metadata structures that are not being rebuilt and have the same rmapbt
+ * owner to generate @sublist. This routine subtracts all the extents
+ * mentioned in sublist from all the extents linked in @exlist, which leaves
+ * @exlist as the list of blocks that are not accounted for, which we assume
+ * are the dead blocks of the old metadata structure. The blocks mentioned in
+ * @exlist can be reaped.
+ */
+#define LEFT_ALIGNED (1 << 0)
+#define RIGHT_ALIGNED (1 << 1)
+int
+xfs_repair_subtract_extents(
+ struct xfs_scrub_context *sc,
+ struct xfs_repair_extent_list *exlist,
+ struct xfs_repair_extent_list *sublist)
+{
+ struct list_head *lp;
+ struct xfs_repair_extent *ex;
+ struct xfs_repair_extent *newex;
+ struct xfs_repair_extent *subex;
+ xfs_fsblock_t sub_fsb;
+ xfs_extlen_t sub_len;
+ int state;
+ int error = 0;
+
+ if (list_empty(&exlist->list) || list_empty(&sublist->list))
+ return 0;
+ ASSERT(!list_empty(&sublist->list));
+
+ list_sort(NULL, &exlist->list, xfs_repair_btree_extent_cmp);
+ list_sort(NULL, &sublist->list, xfs_repair_btree_extent_cmp);
+
+ /*
+ * Now that we've sorted both lists, we iterate exlist once, rolling
+ * forward through sublist and/or exlist as necessary until we find an
+ * overlap or reach the end of either list. We do not reset lp to the
+ * head of exlist nor do we reset subex to the head of sublist. The
+ * list traversal is similar to merge sort, but we're deleting
+ * instead. In this manner we avoid O(n^2) operations.
+ */
+ subex = list_first_entry(&sublist->list, struct xfs_repair_extent,
+ list);
+ lp = exlist->list.next;
+ while (lp != &exlist->list) {
+ ex = list_entry(lp, struct xfs_repair_extent, list);
+
+ /*
+ * Advance subex and/or ex until we find a pair that
+ * intersect or we run out of extents.
+ */
+ while (subex->fsbno + subex->len <= ex->fsbno) {
+ if (list_is_last(&subex->list, &sublist->list))
+ goto out;
+ subex = list_next_entry(subex, list);
+ }
+ if (subex->fsbno >= ex->fsbno + ex->len) {
+ lp = lp->next;
+ continue;
+ }
+
+ /* trim subex to fit the extent we have */
+ sub_fsb = subex->fsbno;
+ sub_len = subex->len;
+ if (subex->fsbno < ex->fsbno) {
+ sub_len -= ex->fsbno - subex->fsbno;
+ sub_fsb = ex->fsbno;
+ }
+ if (sub_len > ex->len)
+ sub_len = ex->len;
+
+ state = 0;
+ if (sub_fsb == ex->fsbno)
+ state |= LEFT_ALIGNED;
+ if (sub_fsb + sub_len == ex->fsbno + ex->len)
+ state |= RIGHT_ALIGNED;
+ switch (state) {
+ case LEFT_ALIGNED:
+ /* Coincides with only the left. */
+ ex->fsbno += sub_len;
+ ex->len -= sub_len;
+ break;
+ case RIGHT_ALIGNED:
+ /* Coincides with only the right. */
+ ex->len -= sub_len;
+ lp = lp->next;
+ break;
+ case LEFT_ALIGNED | RIGHT_ALIGNED:
+ /* Total overlap, just delete ex. */
+ lp = lp->next;
+ list_del(&ex->list);
+ kmem_free(ex);
+ break;
+ case 0:
+ /*
+ * Deleting from the middle: add the new right extent
+ * and then shrink the left extent.
+ */
+ newex = kmem_alloc(sizeof(struct xfs_repair_extent),
+ KM_MAYFAIL);
+ if (!newex) {
+ error = -ENOMEM;
+ goto out;
+ }
+ INIT_LIST_HEAD(&newex->list);
+ newex->fsbno = sub_fsb + sub_len;
+ newex->len = ex->fsbno + ex->len - newex->fsbno;
+ list_add(&newex->list, &ex->list);
+ ex->len = sub_fsb - ex->fsbno;
+ lp = lp->next;
+ break;
+ default:
+ ASSERT(0);
+ break;
+ }
+ }
+
+out:
+ return error;
+}
+#undef LEFT_ALIGNED
+#undef RIGHT_ALIGNED
+
+/*
+ * Disposal of Blocks from Old per-AG Btrees
+ *
+ * Now that we've constructed a new btree to replace the damaged one, we want
+ * to dispose of the blocks that (we think) the old btree was using.
+ * Previously, we used the rmapbt to collect the extents (exlist) with the
+ * rmap owner corresponding to the tree we rebuilt, collected extents for any
+ * blocks with the same rmap owner that are owned by another data structure
+ * (sublist), and subtracted sublist from exlist. In theory the extents
+ * remaining in exlist are the old btree's blocks.
+ *
+ * Unfortunately, it's possible that the btree was crosslinked with other
+ * blocks on disk. The rmap data can tell us if there are multiple owners, so
+ * if the rmapbt says there is an owner of this block other than @oinfo, then
+ * the block is crosslinked. Remove the reverse mapping and continue.
+ *
+ * If there is one rmap record, we can free the block, which removes the
+ * reverse mapping but doesn't add the block to the free space. Our repair
+ * strategy is to hope the other metadata objects crosslinked on this block
+ * will be rebuilt (atop different blocks), thereby removing all the cross
+ * links.
+ *
+ * If there are no rmap records at all, we also free the block. If the btree
+ * being rebuilt lives in the free space (bnobt/cntbt/rmapbt) then there isn't
+ * supposed to be a rmap record and everything is ok. For other btrees there
+ * had to have been an rmap entry for the block to have ended up on @exlist,
+ * so if it's gone now there's something wrong and the fs will shut down.
+ *
+ * Note: If there are multiple rmap records with only the same rmap owner as
+ * the btree we're trying to rebuild and the block is indeed owned by another
+ * data structure with the same rmap owner, then the block will be in sublist
+ * and therefore doesn't need disposal. If there are multiple rmap records
+ * with only the same rmap owner but the block is not owned by something with
+ * the same rmap owner, the block will be freed.
+ *
+ * The caller is responsible for locking the AG headers for the entire rebuild
+ * operation so that nothing else can sneak in and change the AG state while
+ * we're not looking. We also assume that the caller already invalidated any
+ * buffers associated with @exlist.
+ */
+
+/*
+ * Invalidate buffers for per-AG btree blocks we're dumping. This function
+ * is not intended for use with file data repairs; we have bunmapi for that.
+ */
+int
+xfs_repair_invalidate_blocks(
+ struct xfs_scrub_context *sc,
+ struct xfs_repair_extent_list *exlist)
+{
+ struct xfs_repair_extent *rex;
+ struct xfs_repair_extent *n;
+ struct xfs_buf *bp;
+ xfs_fsblock_t fsbno;
+ xfs_agblock_t i;
+
+ /*
+ * For each block in each extent, see if there's an incore buffer for
+ * exactly that block; if so, invalidate it. The buffer cache only
+ * lets us look for one buffer at a time, so we have to look one block
+ * at a time. Avoid invalidating AG headers and post-EOFS blocks
+ * because we never own those; and if we can't TRYLOCK the buffer we
+ * assume it's owned by someone else.
+ */
+ for_each_xfs_repair_extent_safe(rex, n, exlist) {
+ for (fsbno = rex->fsbno, i = rex->len; i > 0; fsbno++, i--) {
+ /* Skip AG headers and post-EOFS blocks */
+ if (!xfs_verify_fsbno(sc->mp, fsbno))
+ continue;
+ bp = xfs_buf_incore(sc->mp->m_ddev_targp,
+ XFS_FSB_TO_DADDR(sc->mp, fsbno),
+ XFS_FSB_TO_BB(sc->mp, 1), XBF_TRYLOCK);
+ if (bp) {
+ xfs_trans_bjoin(sc->tp, bp);
+ xfs_trans_binval(sc->tp, bp);
+ }
+ }
+ }
+
+ return 0;
+}
+
+/* Ensure the freelist is the correct size. */
+int
+xfs_repair_fix_freelist(
+ struct xfs_scrub_context *sc,
+ bool can_shrink)
+{
+ struct xfs_alloc_arg args = {0};
+
+ args.mp = sc->mp;
+ args.tp = sc->tp;
+ args.agno = sc->sa.agno;
+ args.alignment = 1;
+ args.pag = sc->sa.pag;
+
+ return xfs_alloc_fix_freelist(&args,
+ can_shrink ? 0 : XFS_ALLOC_FLAG_NOSHRINK);
+}
+
+/*
+ * Put a block back on the AGFL.
+ */
+STATIC int
+xfs_repair_put_freelist(
+ struct xfs_scrub_context *sc,
+ xfs_agblock_t agbno)
+{
+ struct xfs_owner_info oinfo;
+ int error;
+
+ /* Make sure there's space on the freelist. */
+ error = xfs_repair_fix_freelist(sc, true);
+ if (error)
+ return error;
+
+ /*
+ * Since we're "freeing" a lost block onto the AGFL, we have to
+ * create an rmap for the block prior to merging it or else other
+ * parts will break.
+ */
+ xfs_rmap_ag_owner(&oinfo, XFS_RMAP_OWN_AG);
+ error = xfs_rmap_alloc(sc->tp, sc->sa.agf_bp, sc->sa.agno, agbno, 1,
+ &oinfo);
+ if (error)
+ return error;
+
+ /* Put the block on the AGFL. */
+ error = xfs_alloc_put_freelist(sc->tp, sc->sa.agf_bp, sc->sa.agfl_bp,
+ agbno, 0);
+ if (error)
+ return error;
+ xfs_extent_busy_insert(sc->tp, sc->sa.agno, agbno, 1,
+ XFS_EXTENT_BUSY_SKIP_DISCARD);
+
+ return 0;
+}
+
+/* Dispose of a single metadata block. */
+STATIC int
+xfs_repair_dispose_btree_block(
+ struct xfs_scrub_context *sc,
+ xfs_fsblock_t fsbno,
+ struct xfs_owner_info *oinfo,
+ enum xfs_ag_resv_type resv)
+{
+ struct xfs_btree_cur *cur;
+ struct xfs_buf *agf_bp = NULL;
+ xfs_agnumber_t agno;
+ xfs_agblock_t agbno;
+ bool has_other_rmap;
+ int error;
+
+ agno = XFS_FSB_TO_AGNO(sc->mp, fsbno);
+ agbno = XFS_FSB_TO_AGBNO(sc->mp, fsbno);
+
+ /*
+ * If we are repairing per-inode metadata, we need to read in the AGF
+ * buffer. Otherwise, we're repairing a per-AG structure, so reuse
+ * the AGF buffer that the setup functions already grabbed.
+ */
+ if (sc->ip) {
+ error = xfs_alloc_read_agf(sc->mp, sc->tp, agno, 0, &agf_bp);
+ if (error)
+ return error;
+ if (!agf_bp)
+ return -ENOMEM;
+ } else {
+ agf_bp = sc->sa.agf_bp;
+ }
+ cur = xfs_rmapbt_init_cursor(sc->mp, sc->tp, agf_bp, agno);
+
+ /* Can we find any other rmappings? */
+ error = xfs_rmap_has_other_keys(cur, agbno, 1, oinfo, &has_other_rmap);
+ if (error)
+ goto out_cur;
+ xfs_btree_del_cursor(cur, XFS_BTREE_NOERROR);
+
+ /*
+ * If there are other rmappings, this block is cross linked and must
+ * not be freed. Remove the reverse mapping and move on. Otherwise,
+ * we were the only owner of the block, so free the extent, which will
+ * also remove the rmap.
+ *
+ * XXX: XFS doesn't support detecting the case where a single block
+ * metadata structure is crosslinked with a multi-block structure
+ * because the buffer cache doesn't detect aliasing problems, so we
+ * can't fix 100% of crosslinking problems (yet). The verifiers will
+ * blow on writeout, the filesystem will shut down, and the admin gets
+ * to run xfs_repair.
+ */
+ if (has_other_rmap)
+ error = xfs_rmap_free(sc->tp, agf_bp, agno, agbno, 1, oinfo);
+ else if (resv == XFS_AG_RESV_AGFL)
+ error = xfs_repair_put_freelist(sc, agbno);
+ else
+ error = xfs_free_extent(sc->tp, fsbno, 1, oinfo, resv);
+ if (agf_bp != sc->sa.agf_bp)
+ xfs_trans_brelse(sc->tp, agf_bp);
+ if (error)
+ return error;
+
+ if (sc->ip)
+ return xfs_trans_roll_inode(&sc->tp, sc->ip);
+ return xfs_repair_roll_ag_trans(sc);
+
+out_cur:
+ xfs_btree_del_cursor(cur, XFS_BTREE_ERROR);
+ if (agf_bp != sc->sa.agf_bp)
+ xfs_trans_brelse(sc->tp, agf_bp);
+ return error;
+}
+
+/* Dispose of btree blocks from an old per-AG btree. */
+int
+xfs_repair_reap_btree_extents(
+ struct xfs_scrub_context *sc,
+ struct xfs_repair_extent_list *exlist,
+ struct xfs_owner_info *oinfo,
+ enum xfs_ag_resv_type type)
+{
+ struct xfs_repair_extent *rex;
+ struct xfs_repair_extent *n;
+ int error = 0;
+
+ ASSERT(xfs_sb_version_hasrmapbt(&sc->mp->m_sb));
+
+ /* Dispose of every block from the old btree. */
+ for_each_xfs_repair_extent_safe(rex, n, exlist) {
+ ASSERT(sc->ip != NULL ||
+ XFS_FSB_TO_AGNO(sc->mp, rex->fsbno) == sc->sa.agno);
+
+ trace_xfs_repair_dispose_btree_extent(sc->mp,
+ XFS_FSB_TO_AGNO(sc->mp, rex->fsbno),
+ XFS_FSB_TO_AGBNO(sc->mp, rex->fsbno), rex->len);
+
+ for (; rex->len > 0; rex->len--, rex->fsbno++) {
+ error = xfs_repair_dispose_btree_block(sc, rex->fsbno,
+ oinfo, type);
+ if (error)
+ goto out;
+ }
+ list_del(&rex->list);
+ kmem_free(rex);
+ }
+
+out:
+ xfs_repair_cancel_btree_extents(sc, exlist);
+ return error;
+}
+
+/*
+ * Finding per-AG Btree Roots for AGF/AGI Reconstruction
+ *
+ * If the AGF or AGI become slightly corrupted, it may be necessary to rebuild
+ * the AG headers by using the rmap data to rummage through the AG looking for
+ * btree roots. This is not guaranteed to work if the AG is heavily damaged
+ * or the rmap data are corrupt.
+ *
+ * Callers of xfs_repair_find_ag_btree_roots must lock the AGF and AGFL
+ * buffers if the AGF is being rebuilt; or the AGF and AGI buffers if the
+ * AGI is being rebuilt. It must maintain these locks until it's safe for
+ * other threads to change the btrees' shapes. The caller provides
+ * information about the btrees to look for by passing in an array of
+ * xfs_repair_find_ag_btree with the (rmap owner, buf_ops, magic) fields set.
+ * The (root, height) fields will be set on return if anything is found. The
+ * last element of the array should have a NULL buf_ops to mark the end of the
+ * array.
+ *
+ * For every rmapbt record matching any of the rmap owners in btree_info,
+ * read each block referenced by the rmap record. If the block is a btree
+ * block from this filesystem matching any of the magic numbers and has a
+ * level higher than what we've already seen, remember the block and the
+ * height of the tree required to have such a block. When the call completes,
+ * we return the highest block we've found for each btree description; those
+ * should be the roots.
+ */
+
+struct xfs_repair_findroot {
+ struct xfs_scrub_context *sc;
+ struct xfs_buf *agfl_bp;
+ struct xfs_agf *agf;
+ struct xfs_repair_find_ag_btree *btree_info;
+};
+
+/* See if our block is in the AGFL. */
+STATIC int
+xfs_repair_findroot_agfl_walk(
+ struct xfs_mount *mp,
+ xfs_agblock_t bno,
+ void *priv)
+{
+ xfs_agblock_t *agbno = priv;
+
+ return (*agbno == bno) ? XFS_BTREE_QUERY_RANGE_ABORT : 0;
+}
+
+/* Does this block match the btree information passed in? */
+STATIC int
+xfs_repair_findroot_block(
+ struct xfs_repair_findroot *ri,
+ struct xfs_repair_find_ag_btree *fab,
+ uint64_t owner,
+ xfs_agblock_t agbno,
+ bool *found_it)
+{
+ struct xfs_mount *mp = ri->sc->mp;
+ struct xfs_buf *bp;
+ struct xfs_btree_block *btblock;
+ xfs_daddr_t daddr;
+ int error;
+
+ daddr = XFS_AGB_TO_DADDR(mp, ri->sc->sa.agno, agbno);
+
+ /*
+ * Blocks in the AGFL have stale contents that might just happen to
+ * have a matching magic and uuid. We don't want to pull these blocks
+ * in as part of a tree root, so we have to filter out the AGFL stuff
+ * here. If the AGFL looks insane we'll just refuse to repair.
+ */
+ if (owner == XFS_RMAP_OWN_AG) {
+ error = xfs_agfl_walk(mp, ri->agf, ri->agfl_bp,
+ xfs_repair_findroot_agfl_walk, &agbno);
+ if (error == XFS_BTREE_QUERY_RANGE_ABORT)
+ return 0;
+ if (error)
+ return error;
+ }
+
+ error = xfs_trans_read_buf(mp, ri->sc->tp, mp->m_ddev_targp, daddr,
+ mp->m_bsize, 0, &bp, NULL);
+ if (error)
+ return error;
+
+ /*
+ * Does this look like a block matching our fs and higher than any
+ * other block we've found so far? If so, reattach buffer verifiers
+ * so the AIL won't complain if the buffer is also dirty.
+ */
+ btblock = XFS_BUF_TO_BLOCK(bp);
+ if (be32_to_cpu(btblock->bb_magic) != fab->magic)
+ goto out;
+ if (xfs_sb_version_hascrc(&mp->m_sb) &&
+ !uuid_equal(&btblock->bb_u.s.bb_uuid, &mp->m_sb.sb_meta_uuid))
+ goto out;
+ bp->b_ops = fab->buf_ops;
+
+ /* Ignore this block if it's lower in the tree than we've seen. */
+ if (fab->root != NULLAGBLOCK &&
+ xfs_btree_get_level(btblock) < fab->height)
+ goto out;
+
+ /* Make sure we pass the verifiers. */
+ bp->b_ops->verify_read(bp);
+ if (bp->b_error)
+ goto out;
+ fab->root = agbno;
+ fab->height = xfs_btree_get_level(btblock) + 1;
+ *found_it = true;
+
+ trace_xfs_repair_findroot_block(mp, ri->sc->sa.agno, agbno,
+ be32_to_cpu(btblock->bb_magic), fab->height - 1);
+out:
+ xfs_trans_brelse(ri->sc->tp, bp);
+ return error;
+}
+
+/*
+ * Do any of the blocks in this rmap record match one of the btrees we're
+ * looking for?
+ */
+STATIC int
+xfs_repair_findroot_rmap(
+ struct xfs_btree_cur *cur,
+ struct xfs_rmap_irec *rec,
+ void *priv)
+{
+ struct xfs_repair_findroot *ri = priv;
+ struct xfs_repair_find_ag_btree *fab;
+ xfs_agblock_t b;
+ bool found_it;
+ int error = 0;
+
+ /* Ignore anything that isn't AG metadata. */
+ if (!XFS_RMAP_NON_INODE_OWNER(rec->rm_owner))
+ return 0;
+
+ /* Otherwise scan each block + btree type. */
+ for (b = 0; b < rec->rm_blockcount; b++) {
+ found_it = false;
+ for (fab = ri->btree_info; fab->buf_ops; fab++) {
+ if (rec->rm_owner != fab->rmap_owner)
+ continue;
+ error = xfs_repair_findroot_block(ri, fab,
+ rec->rm_owner, rec->rm_startblock + b,
+ &found_it);
+ if (error)
+ return error;
+ if (found_it)
+ break;
+ }
+ }
+
+ return 0;
+}
+
+/* Find the roots of the per-AG btrees described in btree_info. */
+int
+xfs_repair_find_ag_btree_roots(
+ struct xfs_scrub_context *sc,
+ struct xfs_buf *agf_bp,
+ struct xfs_repair_find_ag_btree *btree_info,
+ struct xfs_buf *agfl_bp)
+{
+ struct xfs_mount *mp = sc->mp;
+ struct xfs_repair_findroot ri;
+ struct xfs_repair_find_ag_btree *fab;
+ struct xfs_btree_cur *cur;
+ int error;
+
+ ASSERT(xfs_buf_islocked(agf_bp));
+ ASSERT(agfl_bp == NULL || xfs_buf_islocked(agfl_bp));
+
+ ri.sc = sc;
+ ri.btree_info = btree_info;
+ ri.agf = XFS_BUF_TO_AGF(agf_bp);
+ ri.agfl_bp = agfl_bp;
+ for (fab = btree_info; fab->buf_ops; fab++) {
+ ASSERT(agfl_bp || fab->rmap_owner != XFS_RMAP_OWN_AG);
+ ASSERT(XFS_RMAP_NON_INODE_OWNER(fab->rmap_owner));
+ fab->root = NULLAGBLOCK;
+ fab->height = 0;
+ }
+
+ cur = xfs_rmapbt_init_cursor(mp, sc->tp, agf_bp, sc->sa.agno);
+ error = xfs_rmap_query_all(cur, xfs_repair_findroot_rmap, &ri);
+ xfs_btree_del_cursor(cur, error ? XFS_BTREE_ERROR : XFS_BTREE_NOERROR);
+
+ return error;
+}
+
+/* Force a quotacheck the next time we mount. */
+void
+xfs_repair_force_quotacheck(
+ struct xfs_scrub_context *sc,
+ uint dqtype)
+{
+ uint flag;
+
+ flag = xfs_quota_chkd_flag(dqtype);
+ if (!(flag & sc->mp->m_qflags))
+ return;
+
+ sc->mp->m_qflags &= ~flag;
+ spin_lock(&sc->mp->m_sb_lock);
+ sc->mp->m_sb.sb_qflags &= ~flag;
+ spin_unlock(&sc->mp->m_sb_lock);
+ xfs_log_sb(sc->tp);
+}
+
+/*
+ * Attach dquots to this inode, or schedule quotacheck to fix them.
+ *
+ * This function ensures that the appropriate dquots are attached to an inode.
+ * We cannot allow the dquot code to allocate an on-disk dquot block here
+ * because we're already in transaction context with the inode locked. The
+ * on-disk dquot should already exist anyway. If the quota code signals
+ * corruption or missing quota information, schedule quotacheck, which will
+ * repair corruptions in the quota metadata.
+ */
+int
+xfs_repair_ino_dqattach(
+ struct xfs_scrub_context *sc)
+{
+ int error;
+
+ error = xfs_qm_dqattach_locked(sc->ip, false);
+ switch (error) {
+ case -EFSBADCRC:
+ case -EFSCORRUPTED:
+ case -ENOENT:
+ xfs_err_ratelimited(sc->mp,
+"inode %llu repair encountered quota error %d, quotacheck forced.",
+ (unsigned long long)sc->ip->i_ino, error);
+ if (XFS_IS_UQUOTA_ON(sc->mp) && !sc->ip->i_udquot)
+ xfs_repair_force_quotacheck(sc, XFS_DQ_USER);
+ if (XFS_IS_GQUOTA_ON(sc->mp) && !sc->ip->i_gdquot)
+ xfs_repair_force_quotacheck(sc, XFS_DQ_GROUP);
+ if (XFS_IS_PQUOTA_ON(sc->mp) && !sc->ip->i_pdquot)
+ xfs_repair_force_quotacheck(sc, XFS_DQ_PROJ);
+ /* fall through */
+ case -ESRCH:
+ error = 0;
+ break;
+ default:
+ break;
+ }
+
+ return error;
+}