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-rw-r--r--fs/xfs/scrub/bmap.c959
1 files changed, 959 insertions, 0 deletions
diff --git a/fs/xfs/scrub/bmap.c b/fs/xfs/scrub/bmap.c
new file mode 100644
index 0000000000..7558891557
--- /dev/null
+++ b/fs/xfs/scrub/bmap.c
@@ -0,0 +1,959 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (C) 2017-2023 Oracle. All Rights Reserved.
+ * Author: Darrick J. Wong <djwong@kernel.org>
+ */
+#include "xfs.h"
+#include "xfs_fs.h"
+#include "xfs_shared.h"
+#include "xfs_format.h"
+#include "xfs_trans_resv.h"
+#include "xfs_mount.h"
+#include "xfs_btree.h"
+#include "xfs_bit.h"
+#include "xfs_log_format.h"
+#include "xfs_trans.h"
+#include "xfs_inode.h"
+#include "xfs_alloc.h"
+#include "xfs_bmap.h"
+#include "xfs_bmap_btree.h"
+#include "xfs_rmap.h"
+#include "xfs_rmap_btree.h"
+#include "scrub/scrub.h"
+#include "scrub/common.h"
+#include "scrub/btree.h"
+#include "xfs_ag.h"
+
+/* Set us up with an inode's bmap. */
+int
+xchk_setup_inode_bmap(
+ struct xfs_scrub *sc)
+{
+ int error;
+
+ if (xchk_need_intent_drain(sc))
+ xchk_fsgates_enable(sc, XCHK_FSGATES_DRAIN);
+
+ error = xchk_iget_for_scrubbing(sc);
+ if (error)
+ goto out;
+
+ xchk_ilock(sc, XFS_IOLOCK_EXCL);
+
+ /*
+ * We don't want any ephemeral data/cow fork updates sitting around
+ * while we inspect block mappings, so wait for directio to finish
+ * and flush dirty data if we have delalloc reservations.
+ */
+ if (S_ISREG(VFS_I(sc->ip)->i_mode) &&
+ sc->sm->sm_type != XFS_SCRUB_TYPE_BMBTA) {
+ struct address_space *mapping = VFS_I(sc->ip)->i_mapping;
+
+ xchk_ilock(sc, XFS_MMAPLOCK_EXCL);
+
+ inode_dio_wait(VFS_I(sc->ip));
+
+ /*
+ * Try to flush all incore state to disk before we examine the
+ * space mappings for the data fork. Leave accumulated errors
+ * in the mapping for the writer threads to consume.
+ *
+ * On ENOSPC or EIO writeback errors, we continue into the
+ * extent mapping checks because write failures do not
+ * necessarily imply anything about the correctness of the file
+ * metadata. The metadata and the file data could be on
+ * completely separate devices; a media failure might only
+ * affect a subset of the disk, etc. We can handle delalloc
+ * extents in the scrubber, so leaving them in memory is fine.
+ */
+ error = filemap_fdatawrite(mapping);
+ if (!error)
+ error = filemap_fdatawait_keep_errors(mapping);
+ if (error && (error != -ENOSPC && error != -EIO))
+ goto out;
+ }
+
+ /* Got the inode, lock it and we're ready to go. */
+ error = xchk_trans_alloc(sc, 0);
+ if (error)
+ goto out;
+
+ xchk_ilock(sc, XFS_ILOCK_EXCL);
+out:
+ /* scrub teardown will unlock and release the inode */
+ return error;
+}
+
+/*
+ * Inode fork block mapping (BMBT) scrubber.
+ * More complex than the others because we have to scrub
+ * all the extents regardless of whether or not the fork
+ * is in btree format.
+ */
+
+struct xchk_bmap_info {
+ struct xfs_scrub *sc;
+
+ /* Incore extent tree cursor */
+ struct xfs_iext_cursor icur;
+
+ /* Previous fork mapping that we examined */
+ struct xfs_bmbt_irec prev_rec;
+
+ /* Is this a realtime fork? */
+ bool is_rt;
+
+ /* May mappings point to shared space? */
+ bool is_shared;
+
+ /* Was the incore extent tree loaded? */
+ bool was_loaded;
+
+ /* Which inode fork are we checking? */
+ int whichfork;
+};
+
+/* Look for a corresponding rmap for this irec. */
+static inline bool
+xchk_bmap_get_rmap(
+ struct xchk_bmap_info *info,
+ struct xfs_bmbt_irec *irec,
+ xfs_agblock_t agbno,
+ uint64_t owner,
+ struct xfs_rmap_irec *rmap)
+{
+ xfs_fileoff_t offset;
+ unsigned int rflags = 0;
+ int has_rmap;
+ int error;
+
+ if (info->whichfork == XFS_ATTR_FORK)
+ rflags |= XFS_RMAP_ATTR_FORK;
+ if (irec->br_state == XFS_EXT_UNWRITTEN)
+ rflags |= XFS_RMAP_UNWRITTEN;
+
+ /*
+ * CoW staging extents are owned (on disk) by the refcountbt, so
+ * their rmaps do not have offsets.
+ */
+ if (info->whichfork == XFS_COW_FORK)
+ offset = 0;
+ else
+ offset = irec->br_startoff;
+
+ /*
+ * If the caller thinks this could be a shared bmbt extent (IOWs,
+ * any data fork extent of a reflink inode) then we have to use the
+ * range rmap lookup to make sure we get the correct owner/offset.
+ */
+ if (info->is_shared) {
+ error = xfs_rmap_lookup_le_range(info->sc->sa.rmap_cur, agbno,
+ owner, offset, rflags, rmap, &has_rmap);
+ } else {
+ error = xfs_rmap_lookup_le(info->sc->sa.rmap_cur, agbno,
+ owner, offset, rflags, rmap, &has_rmap);
+ }
+ if (!xchk_should_check_xref(info->sc, &error, &info->sc->sa.rmap_cur))
+ return false;
+
+ if (!has_rmap)
+ xchk_fblock_xref_set_corrupt(info->sc, info->whichfork,
+ irec->br_startoff);
+ return has_rmap;
+}
+
+/* Make sure that we have rmapbt records for this data/attr fork extent. */
+STATIC void
+xchk_bmap_xref_rmap(
+ struct xchk_bmap_info *info,
+ struct xfs_bmbt_irec *irec,
+ xfs_agblock_t agbno)
+{
+ struct xfs_rmap_irec rmap;
+ unsigned long long rmap_end;
+ uint64_t owner = info->sc->ip->i_ino;
+
+ if (!info->sc->sa.rmap_cur || xchk_skip_xref(info->sc->sm))
+ return;
+
+ /* Find the rmap record for this irec. */
+ if (!xchk_bmap_get_rmap(info, irec, agbno, owner, &rmap))
+ return;
+
+ /*
+ * The rmap must be an exact match for this incore file mapping record,
+ * which may have arisen from multiple ondisk records.
+ */
+ if (rmap.rm_startblock != agbno)
+ xchk_fblock_xref_set_corrupt(info->sc, info->whichfork,
+ irec->br_startoff);
+
+ rmap_end = (unsigned long long)rmap.rm_startblock + rmap.rm_blockcount;
+ if (rmap_end != agbno + irec->br_blockcount)
+ xchk_fblock_xref_set_corrupt(info->sc, info->whichfork,
+ irec->br_startoff);
+
+ /* Check the logical offsets. */
+ if (rmap.rm_offset != irec->br_startoff)
+ xchk_fblock_xref_set_corrupt(info->sc, info->whichfork,
+ irec->br_startoff);
+
+ rmap_end = (unsigned long long)rmap.rm_offset + rmap.rm_blockcount;
+ if (rmap_end != irec->br_startoff + irec->br_blockcount)
+ xchk_fblock_xref_set_corrupt(info->sc, info->whichfork,
+ irec->br_startoff);
+
+ /* Check the owner */
+ if (rmap.rm_owner != owner)
+ xchk_fblock_xref_set_corrupt(info->sc, info->whichfork,
+ irec->br_startoff);
+
+ /*
+ * Check for discrepancies between the unwritten flag in the irec and
+ * the rmap. Note that the (in-memory) CoW fork distinguishes between
+ * unwritten and written extents, but we don't track that in the rmap
+ * records because the blocks are owned (on-disk) by the refcountbt,
+ * which doesn't track unwritten state.
+ */
+ if (!!(irec->br_state == XFS_EXT_UNWRITTEN) !=
+ !!(rmap.rm_flags & XFS_RMAP_UNWRITTEN))
+ xchk_fblock_xref_set_corrupt(info->sc, info->whichfork,
+ irec->br_startoff);
+
+ if (!!(info->whichfork == XFS_ATTR_FORK) !=
+ !!(rmap.rm_flags & XFS_RMAP_ATTR_FORK))
+ xchk_fblock_xref_set_corrupt(info->sc, info->whichfork,
+ irec->br_startoff);
+ if (rmap.rm_flags & XFS_RMAP_BMBT_BLOCK)
+ xchk_fblock_xref_set_corrupt(info->sc, info->whichfork,
+ irec->br_startoff);
+}
+
+/* Make sure that we have rmapbt records for this COW fork extent. */
+STATIC void
+xchk_bmap_xref_rmap_cow(
+ struct xchk_bmap_info *info,
+ struct xfs_bmbt_irec *irec,
+ xfs_agblock_t agbno)
+{
+ struct xfs_rmap_irec rmap;
+ unsigned long long rmap_end;
+ uint64_t owner = XFS_RMAP_OWN_COW;
+
+ if (!info->sc->sa.rmap_cur || xchk_skip_xref(info->sc->sm))
+ return;
+
+ /* Find the rmap record for this irec. */
+ if (!xchk_bmap_get_rmap(info, irec, agbno, owner, &rmap))
+ return;
+
+ /*
+ * CoW staging extents are owned by the refcount btree, so the rmap
+ * can start before and end after the physical space allocated to this
+ * mapping. There are no offsets to check.
+ */
+ if (rmap.rm_startblock > agbno)
+ xchk_fblock_xref_set_corrupt(info->sc, info->whichfork,
+ irec->br_startoff);
+
+ rmap_end = (unsigned long long)rmap.rm_startblock + rmap.rm_blockcount;
+ if (rmap_end < agbno + irec->br_blockcount)
+ xchk_fblock_xref_set_corrupt(info->sc, info->whichfork,
+ irec->br_startoff);
+
+ /* Check the owner */
+ if (rmap.rm_owner != owner)
+ xchk_fblock_xref_set_corrupt(info->sc, info->whichfork,
+ irec->br_startoff);
+
+ /*
+ * No flags allowed. Note that the (in-memory) CoW fork distinguishes
+ * between unwritten and written extents, but we don't track that in
+ * the rmap records because the blocks are owned (on-disk) by the
+ * refcountbt, which doesn't track unwritten state.
+ */
+ if (rmap.rm_flags & XFS_RMAP_ATTR_FORK)
+ xchk_fblock_xref_set_corrupt(info->sc, info->whichfork,
+ irec->br_startoff);
+ if (rmap.rm_flags & XFS_RMAP_BMBT_BLOCK)
+ xchk_fblock_xref_set_corrupt(info->sc, info->whichfork,
+ irec->br_startoff);
+ if (rmap.rm_flags & XFS_RMAP_UNWRITTEN)
+ xchk_fblock_xref_set_corrupt(info->sc, info->whichfork,
+ irec->br_startoff);
+}
+
+/* Cross-reference a single rtdev extent record. */
+STATIC void
+xchk_bmap_rt_iextent_xref(
+ struct xfs_inode *ip,
+ struct xchk_bmap_info *info,
+ struct xfs_bmbt_irec *irec)
+{
+ xchk_xref_is_used_rt_space(info->sc, irec->br_startblock,
+ irec->br_blockcount);
+}
+
+/* Cross-reference a single datadev extent record. */
+STATIC void
+xchk_bmap_iextent_xref(
+ struct xfs_inode *ip,
+ struct xchk_bmap_info *info,
+ struct xfs_bmbt_irec *irec)
+{
+ struct xfs_owner_info oinfo;
+ struct xfs_mount *mp = info->sc->mp;
+ xfs_agnumber_t agno;
+ xfs_agblock_t agbno;
+ xfs_extlen_t len;
+ int error;
+
+ agno = XFS_FSB_TO_AGNO(mp, irec->br_startblock);
+ agbno = XFS_FSB_TO_AGBNO(mp, irec->br_startblock);
+ len = irec->br_blockcount;
+
+ error = xchk_ag_init_existing(info->sc, agno, &info->sc->sa);
+ if (!xchk_fblock_process_error(info->sc, info->whichfork,
+ irec->br_startoff, &error))
+ goto out_free;
+
+ xchk_xref_is_used_space(info->sc, agbno, len);
+ xchk_xref_is_not_inode_chunk(info->sc, agbno, len);
+ switch (info->whichfork) {
+ case XFS_DATA_FORK:
+ xchk_bmap_xref_rmap(info, irec, agbno);
+ if (!xfs_is_reflink_inode(info->sc->ip)) {
+ xfs_rmap_ino_owner(&oinfo, info->sc->ip->i_ino,
+ info->whichfork, irec->br_startoff);
+ xchk_xref_is_only_owned_by(info->sc, agbno,
+ irec->br_blockcount, &oinfo);
+ xchk_xref_is_not_shared(info->sc, agbno,
+ irec->br_blockcount);
+ }
+ xchk_xref_is_not_cow_staging(info->sc, agbno,
+ irec->br_blockcount);
+ break;
+ case XFS_ATTR_FORK:
+ xchk_bmap_xref_rmap(info, irec, agbno);
+ xfs_rmap_ino_owner(&oinfo, info->sc->ip->i_ino,
+ info->whichfork, irec->br_startoff);
+ xchk_xref_is_only_owned_by(info->sc, agbno, irec->br_blockcount,
+ &oinfo);
+ xchk_xref_is_not_shared(info->sc, agbno,
+ irec->br_blockcount);
+ xchk_xref_is_not_cow_staging(info->sc, agbno,
+ irec->br_blockcount);
+ break;
+ case XFS_COW_FORK:
+ xchk_bmap_xref_rmap_cow(info, irec, agbno);
+ xchk_xref_is_only_owned_by(info->sc, agbno, irec->br_blockcount,
+ &XFS_RMAP_OINFO_COW);
+ xchk_xref_is_cow_staging(info->sc, agbno,
+ irec->br_blockcount);
+ xchk_xref_is_not_shared(info->sc, agbno,
+ irec->br_blockcount);
+ break;
+ }
+
+out_free:
+ xchk_ag_free(info->sc, &info->sc->sa);
+}
+
+/*
+ * Directories and attr forks should never have blocks that can't be addressed
+ * by a xfs_dablk_t.
+ */
+STATIC void
+xchk_bmap_dirattr_extent(
+ struct xfs_inode *ip,
+ struct xchk_bmap_info *info,
+ struct xfs_bmbt_irec *irec)
+{
+ struct xfs_mount *mp = ip->i_mount;
+ xfs_fileoff_t off;
+
+ if (!S_ISDIR(VFS_I(ip)->i_mode) && info->whichfork != XFS_ATTR_FORK)
+ return;
+
+ if (!xfs_verify_dablk(mp, irec->br_startoff))
+ xchk_fblock_set_corrupt(info->sc, info->whichfork,
+ irec->br_startoff);
+
+ off = irec->br_startoff + irec->br_blockcount - 1;
+ if (!xfs_verify_dablk(mp, off))
+ xchk_fblock_set_corrupt(info->sc, info->whichfork, off);
+}
+
+/* Scrub a single extent record. */
+STATIC void
+xchk_bmap_iextent(
+ struct xfs_inode *ip,
+ struct xchk_bmap_info *info,
+ struct xfs_bmbt_irec *irec)
+{
+ struct xfs_mount *mp = info->sc->mp;
+
+ /*
+ * Check for out-of-order extents. This record could have come
+ * from the incore list, for which there is no ordering check.
+ */
+ if (irec->br_startoff < info->prev_rec.br_startoff +
+ info->prev_rec.br_blockcount)
+ xchk_fblock_set_corrupt(info->sc, info->whichfork,
+ irec->br_startoff);
+
+ if (!xfs_verify_fileext(mp, irec->br_startoff, irec->br_blockcount))
+ xchk_fblock_set_corrupt(info->sc, info->whichfork,
+ irec->br_startoff);
+
+ xchk_bmap_dirattr_extent(ip, info, irec);
+
+ /* Make sure the extent points to a valid place. */
+ if (info->is_rt &&
+ !xfs_verify_rtext(mp, irec->br_startblock, irec->br_blockcount))
+ xchk_fblock_set_corrupt(info->sc, info->whichfork,
+ irec->br_startoff);
+ if (!info->is_rt &&
+ !xfs_verify_fsbext(mp, irec->br_startblock, irec->br_blockcount))
+ xchk_fblock_set_corrupt(info->sc, info->whichfork,
+ irec->br_startoff);
+
+ /* We don't allow unwritten extents on attr forks. */
+ if (irec->br_state == XFS_EXT_UNWRITTEN &&
+ info->whichfork == XFS_ATTR_FORK)
+ xchk_fblock_set_corrupt(info->sc, info->whichfork,
+ irec->br_startoff);
+
+ if (info->sc->sm->sm_flags & XFS_SCRUB_OFLAG_CORRUPT)
+ return;
+
+ if (info->is_rt)
+ xchk_bmap_rt_iextent_xref(ip, info, irec);
+ else
+ xchk_bmap_iextent_xref(ip, info, irec);
+}
+
+/* Scrub a bmbt record. */
+STATIC int
+xchk_bmapbt_rec(
+ struct xchk_btree *bs,
+ const union xfs_btree_rec *rec)
+{
+ struct xfs_bmbt_irec irec;
+ struct xfs_bmbt_irec iext_irec;
+ struct xfs_iext_cursor icur;
+ struct xchk_bmap_info *info = bs->private;
+ struct xfs_inode *ip = bs->cur->bc_ino.ip;
+ struct xfs_buf *bp = NULL;
+ struct xfs_btree_block *block;
+ struct xfs_ifork *ifp = xfs_ifork_ptr(ip, info->whichfork);
+ uint64_t owner;
+ int i;
+
+ /*
+ * Check the owners of the btree blocks up to the level below
+ * the root since the verifiers don't do that.
+ */
+ if (xfs_has_crc(bs->cur->bc_mp) &&
+ bs->cur->bc_levels[0].ptr == 1) {
+ for (i = 0; i < bs->cur->bc_nlevels - 1; i++) {
+ block = xfs_btree_get_block(bs->cur, i, &bp);
+ owner = be64_to_cpu(block->bb_u.l.bb_owner);
+ if (owner != ip->i_ino)
+ xchk_fblock_set_corrupt(bs->sc,
+ info->whichfork, 0);
+ }
+ }
+
+ /*
+ * Check that the incore extent tree contains an extent that matches
+ * this one exactly. We validate those cached bmaps later, so we don't
+ * need to check them here. If the incore extent tree was just loaded
+ * from disk by the scrubber, we assume that its contents match what's
+ * on disk (we still hold the ILOCK) and skip the equivalence check.
+ */
+ if (!info->was_loaded)
+ return 0;
+
+ xfs_bmbt_disk_get_all(&rec->bmbt, &irec);
+ if (xfs_bmap_validate_extent(ip, info->whichfork, &irec) != NULL) {
+ xchk_fblock_set_corrupt(bs->sc, info->whichfork,
+ irec.br_startoff);
+ return 0;
+ }
+
+ if (!xfs_iext_lookup_extent(ip, ifp, irec.br_startoff, &icur,
+ &iext_irec) ||
+ irec.br_startoff != iext_irec.br_startoff ||
+ irec.br_startblock != iext_irec.br_startblock ||
+ irec.br_blockcount != iext_irec.br_blockcount ||
+ irec.br_state != iext_irec.br_state)
+ xchk_fblock_set_corrupt(bs->sc, info->whichfork,
+ irec.br_startoff);
+ return 0;
+}
+
+/* Scan the btree records. */
+STATIC int
+xchk_bmap_btree(
+ struct xfs_scrub *sc,
+ int whichfork,
+ struct xchk_bmap_info *info)
+{
+ struct xfs_owner_info oinfo;
+ struct xfs_ifork *ifp = xfs_ifork_ptr(sc->ip, whichfork);
+ struct xfs_mount *mp = sc->mp;
+ struct xfs_inode *ip = sc->ip;
+ struct xfs_btree_cur *cur;
+ int error;
+
+ /* Load the incore bmap cache if it's not loaded. */
+ info->was_loaded = !xfs_need_iread_extents(ifp);
+
+ error = xfs_iread_extents(sc->tp, ip, whichfork);
+ if (!xchk_fblock_process_error(sc, whichfork, 0, &error))
+ goto out;
+
+ /* Check the btree structure. */
+ cur = xfs_bmbt_init_cursor(mp, sc->tp, ip, whichfork);
+ xfs_rmap_ino_bmbt_owner(&oinfo, ip->i_ino, whichfork);
+ error = xchk_btree(sc, cur, xchk_bmapbt_rec, &oinfo, info);
+ xfs_btree_del_cursor(cur, error);
+out:
+ return error;
+}
+
+struct xchk_bmap_check_rmap_info {
+ struct xfs_scrub *sc;
+ int whichfork;
+ struct xfs_iext_cursor icur;
+};
+
+/* Can we find bmaps that fit this rmap? */
+STATIC int
+xchk_bmap_check_rmap(
+ struct xfs_btree_cur *cur,
+ const struct xfs_rmap_irec *rec,
+ void *priv)
+{
+ struct xfs_bmbt_irec irec;
+ struct xfs_rmap_irec check_rec;
+ struct xchk_bmap_check_rmap_info *sbcri = priv;
+ struct xfs_ifork *ifp;
+ struct xfs_scrub *sc = sbcri->sc;
+ bool have_map;
+
+ /* Is this even the right fork? */
+ if (rec->rm_owner != sc->ip->i_ino)
+ return 0;
+ if ((sbcri->whichfork == XFS_ATTR_FORK) ^
+ !!(rec->rm_flags & XFS_RMAP_ATTR_FORK))
+ return 0;
+ if (rec->rm_flags & XFS_RMAP_BMBT_BLOCK)
+ return 0;
+
+ /* Now look up the bmbt record. */
+ ifp = xfs_ifork_ptr(sc->ip, sbcri->whichfork);
+ if (!ifp) {
+ xchk_fblock_set_corrupt(sc, sbcri->whichfork,
+ rec->rm_offset);
+ goto out;
+ }
+ have_map = xfs_iext_lookup_extent(sc->ip, ifp, rec->rm_offset,
+ &sbcri->icur, &irec);
+ if (!have_map)
+ xchk_fblock_set_corrupt(sc, sbcri->whichfork,
+ rec->rm_offset);
+ /*
+ * bmap extent record lengths are constrained to 2^21 blocks in length
+ * because of space constraints in the on-disk metadata structure.
+ * However, rmap extent record lengths are constrained only by AG
+ * length, so we have to loop through the bmbt to make sure that the
+ * entire rmap is covered by bmbt records.
+ */
+ check_rec = *rec;
+ while (have_map) {
+ if (irec.br_startoff != check_rec.rm_offset)
+ xchk_fblock_set_corrupt(sc, sbcri->whichfork,
+ check_rec.rm_offset);
+ if (irec.br_startblock != XFS_AGB_TO_FSB(sc->mp,
+ cur->bc_ag.pag->pag_agno,
+ check_rec.rm_startblock))
+ xchk_fblock_set_corrupt(sc, sbcri->whichfork,
+ check_rec.rm_offset);
+ if (irec.br_blockcount > check_rec.rm_blockcount)
+ xchk_fblock_set_corrupt(sc, sbcri->whichfork,
+ check_rec.rm_offset);
+ if (sc->sm->sm_flags & XFS_SCRUB_OFLAG_CORRUPT)
+ break;
+ check_rec.rm_startblock += irec.br_blockcount;
+ check_rec.rm_offset += irec.br_blockcount;
+ check_rec.rm_blockcount -= irec.br_blockcount;
+ if (check_rec.rm_blockcount == 0)
+ break;
+ have_map = xfs_iext_next_extent(ifp, &sbcri->icur, &irec);
+ if (!have_map)
+ xchk_fblock_set_corrupt(sc, sbcri->whichfork,
+ check_rec.rm_offset);
+ }
+
+out:
+ if (sc->sm->sm_flags & XFS_SCRUB_OFLAG_CORRUPT)
+ return -ECANCELED;
+ return 0;
+}
+
+/* Make sure each rmap has a corresponding bmbt entry. */
+STATIC int
+xchk_bmap_check_ag_rmaps(
+ struct xfs_scrub *sc,
+ int whichfork,
+ struct xfs_perag *pag)
+{
+ struct xchk_bmap_check_rmap_info sbcri;
+ struct xfs_btree_cur *cur;
+ struct xfs_buf *agf;
+ int error;
+
+ error = xfs_alloc_read_agf(pag, sc->tp, 0, &agf);
+ if (error)
+ return error;
+
+ cur = xfs_rmapbt_init_cursor(sc->mp, sc->tp, agf, pag);
+
+ sbcri.sc = sc;
+ sbcri.whichfork = whichfork;
+ error = xfs_rmap_query_all(cur, xchk_bmap_check_rmap, &sbcri);
+ if (error == -ECANCELED)
+ error = 0;
+
+ xfs_btree_del_cursor(cur, error);
+ xfs_trans_brelse(sc->tp, agf);
+ return error;
+}
+
+/*
+ * Decide if we want to walk every rmap btree in the fs to make sure that each
+ * rmap for this file fork has corresponding bmbt entries.
+ */
+static bool
+xchk_bmap_want_check_rmaps(
+ struct xchk_bmap_info *info)
+{
+ struct xfs_scrub *sc = info->sc;
+ struct xfs_ifork *ifp;
+
+ if (!xfs_has_rmapbt(sc->mp))
+ return false;
+ if (info->whichfork == XFS_COW_FORK)
+ return false;
+ if (sc->sm->sm_flags & XFS_SCRUB_OFLAG_CORRUPT)
+ return false;
+
+ /* Don't support realtime rmap checks yet. */
+ if (info->is_rt)
+ return false;
+
+ /*
+ * The inode repair code zaps broken inode forks by resetting them back
+ * to EXTENTS format and zero extent records. If we encounter a fork
+ * in this state along with evidence that the fork isn't supposed to be
+ * empty, we need to scan the reverse mappings to decide if we're going
+ * to rebuild the fork. Data forks with nonzero file size are scanned.
+ * xattr forks are never empty of content, so they are always scanned.
+ */
+ ifp = xfs_ifork_ptr(sc->ip, info->whichfork);
+ if (ifp->if_format == XFS_DINODE_FMT_EXTENTS && ifp->if_nextents == 0) {
+ if (info->whichfork == XFS_DATA_FORK &&
+ i_size_read(VFS_I(sc->ip)) == 0)
+ return false;
+
+ return true;
+ }
+
+ return false;
+}
+
+/* Make sure each rmap has a corresponding bmbt entry. */
+STATIC int
+xchk_bmap_check_rmaps(
+ struct xfs_scrub *sc,
+ int whichfork)
+{
+ struct xfs_perag *pag;
+ xfs_agnumber_t agno;
+ int error;
+
+ for_each_perag(sc->mp, agno, pag) {
+ error = xchk_bmap_check_ag_rmaps(sc, whichfork, pag);
+ if (error ||
+ (sc->sm->sm_flags & XFS_SCRUB_OFLAG_CORRUPT)) {
+ xfs_perag_rele(pag);
+ return error;
+ }
+ }
+
+ return 0;
+}
+
+/* Scrub a delalloc reservation from the incore extent map tree. */
+STATIC void
+xchk_bmap_iextent_delalloc(
+ struct xfs_inode *ip,
+ struct xchk_bmap_info *info,
+ struct xfs_bmbt_irec *irec)
+{
+ struct xfs_mount *mp = info->sc->mp;
+
+ /*
+ * Check for out-of-order extents. This record could have come
+ * from the incore list, for which there is no ordering check.
+ */
+ if (irec->br_startoff < info->prev_rec.br_startoff +
+ info->prev_rec.br_blockcount)
+ xchk_fblock_set_corrupt(info->sc, info->whichfork,
+ irec->br_startoff);
+
+ if (!xfs_verify_fileext(mp, irec->br_startoff, irec->br_blockcount))
+ xchk_fblock_set_corrupt(info->sc, info->whichfork,
+ irec->br_startoff);
+
+ /* Make sure the extent points to a valid place. */
+ if (irec->br_blockcount > XFS_MAX_BMBT_EXTLEN)
+ xchk_fblock_set_corrupt(info->sc, info->whichfork,
+ irec->br_startoff);
+}
+
+/* Decide if this individual fork mapping is ok. */
+static bool
+xchk_bmap_iext_mapping(
+ struct xchk_bmap_info *info,
+ const struct xfs_bmbt_irec *irec)
+{
+ /* There should never be a "hole" extent in either extent list. */
+ if (irec->br_startblock == HOLESTARTBLOCK)
+ return false;
+ if (irec->br_blockcount > XFS_MAX_BMBT_EXTLEN)
+ return false;
+ return true;
+}
+
+/* Are these two mappings contiguous with each other? */
+static inline bool
+xchk_are_bmaps_contiguous(
+ const struct xfs_bmbt_irec *b1,
+ const struct xfs_bmbt_irec *b2)
+{
+ /* Don't try to combine unallocated mappings. */
+ if (!xfs_bmap_is_real_extent(b1))
+ return false;
+ if (!xfs_bmap_is_real_extent(b2))
+ return false;
+
+ /* Does b2 come right after b1 in the logical and physical range? */
+ if (b1->br_startoff + b1->br_blockcount != b2->br_startoff)
+ return false;
+ if (b1->br_startblock + b1->br_blockcount != b2->br_startblock)
+ return false;
+ if (b1->br_state != b2->br_state)
+ return false;
+ return true;
+}
+
+/*
+ * Walk the incore extent records, accumulating consecutive contiguous records
+ * into a single incore mapping. Returns true if @irec has been set to a
+ * mapping or false if there are no more mappings. Caller must ensure that
+ * @info.icur is zeroed before the first call.
+ */
+static bool
+xchk_bmap_iext_iter(
+ struct xchk_bmap_info *info,
+ struct xfs_bmbt_irec *irec)
+{
+ struct xfs_bmbt_irec got;
+ struct xfs_ifork *ifp;
+ unsigned int nr = 0;
+
+ ifp = xfs_ifork_ptr(info->sc->ip, info->whichfork);
+
+ /* Advance to the next iextent record and check the mapping. */
+ xfs_iext_next(ifp, &info->icur);
+ if (!xfs_iext_get_extent(ifp, &info->icur, irec))
+ return false;
+
+ if (!xchk_bmap_iext_mapping(info, irec)) {
+ xchk_fblock_set_corrupt(info->sc, info->whichfork,
+ irec->br_startoff);
+ return false;
+ }
+ nr++;
+
+ /*
+ * Iterate subsequent iextent records and merge them with the one
+ * that we just read, if possible.
+ */
+ while (xfs_iext_peek_next_extent(ifp, &info->icur, &got)) {
+ if (!xchk_are_bmaps_contiguous(irec, &got))
+ break;
+
+ if (!xchk_bmap_iext_mapping(info, &got)) {
+ xchk_fblock_set_corrupt(info->sc, info->whichfork,
+ got.br_startoff);
+ return false;
+ }
+ nr++;
+
+ irec->br_blockcount += got.br_blockcount;
+ xfs_iext_next(ifp, &info->icur);
+ }
+
+ /*
+ * If the merged mapping could be expressed with fewer bmbt records
+ * than we actually found, notify the user that this fork could be
+ * optimized. CoW forks only exist in memory so we ignore them.
+ */
+ if (nr > 1 && info->whichfork != XFS_COW_FORK &&
+ howmany_64(irec->br_blockcount, XFS_MAX_BMBT_EXTLEN) < nr)
+ xchk_ino_set_preen(info->sc, info->sc->ip->i_ino);
+
+ return true;
+}
+
+/*
+ * Scrub an inode fork's block mappings.
+ *
+ * First we scan every record in every btree block, if applicable.
+ * Then we unconditionally scan the incore extent cache.
+ */
+STATIC int
+xchk_bmap(
+ struct xfs_scrub *sc,
+ int whichfork)
+{
+ struct xfs_bmbt_irec irec;
+ struct xchk_bmap_info info = { NULL };
+ struct xfs_mount *mp = sc->mp;
+ struct xfs_inode *ip = sc->ip;
+ struct xfs_ifork *ifp = xfs_ifork_ptr(ip, whichfork);
+ xfs_fileoff_t endoff;
+ int error = 0;
+
+ /* Non-existent forks can be ignored. */
+ if (!ifp)
+ return -ENOENT;
+
+ info.is_rt = whichfork == XFS_DATA_FORK && XFS_IS_REALTIME_INODE(ip);
+ info.whichfork = whichfork;
+ info.is_shared = whichfork == XFS_DATA_FORK && xfs_is_reflink_inode(ip);
+ info.sc = sc;
+
+ switch (whichfork) {
+ case XFS_COW_FORK:
+ /* No CoW forks on non-reflink filesystems. */
+ if (!xfs_has_reflink(mp)) {
+ xchk_ino_set_corrupt(sc, sc->ip->i_ino);
+ return 0;
+ }
+ break;
+ case XFS_ATTR_FORK:
+ if (!xfs_has_attr(mp) && !xfs_has_attr2(mp))
+ xchk_ino_set_corrupt(sc, sc->ip->i_ino);
+ break;
+ default:
+ ASSERT(whichfork == XFS_DATA_FORK);
+ break;
+ }
+
+ /* Check the fork values */
+ switch (ifp->if_format) {
+ case XFS_DINODE_FMT_UUID:
+ case XFS_DINODE_FMT_DEV:
+ case XFS_DINODE_FMT_LOCAL:
+ /* No mappings to check. */
+ if (whichfork == XFS_COW_FORK)
+ xchk_fblock_set_corrupt(sc, whichfork, 0);
+ return 0;
+ case XFS_DINODE_FMT_EXTENTS:
+ break;
+ case XFS_DINODE_FMT_BTREE:
+ if (whichfork == XFS_COW_FORK) {
+ xchk_fblock_set_corrupt(sc, whichfork, 0);
+ return 0;
+ }
+
+ error = xchk_bmap_btree(sc, whichfork, &info);
+ if (error)
+ return error;
+ break;
+ default:
+ xchk_fblock_set_corrupt(sc, whichfork, 0);
+ return 0;
+ }
+
+ if (sc->sm->sm_flags & XFS_SCRUB_OFLAG_CORRUPT)
+ return 0;
+
+ /* Find the offset of the last extent in the mapping. */
+ error = xfs_bmap_last_offset(ip, &endoff, whichfork);
+ if (!xchk_fblock_process_error(sc, whichfork, 0, &error))
+ return error;
+
+ /*
+ * Scrub extent records. We use a special iterator function here that
+ * combines adjacent mappings if they are logically and physically
+ * contiguous. For large allocations that require multiple bmbt
+ * records, this reduces the number of cross-referencing calls, which
+ * reduces runtime. Cross referencing with the rmap is simpler because
+ * the rmap must match the combined mapping exactly.
+ */
+ while (xchk_bmap_iext_iter(&info, &irec)) {
+ if (xchk_should_terminate(sc, &error) ||
+ (sc->sm->sm_flags & XFS_SCRUB_OFLAG_CORRUPT))
+ return 0;
+
+ if (irec.br_startoff >= endoff) {
+ xchk_fblock_set_corrupt(sc, whichfork,
+ irec.br_startoff);
+ return 0;
+ }
+
+ if (isnullstartblock(irec.br_startblock))
+ xchk_bmap_iextent_delalloc(ip, &info, &irec);
+ else
+ xchk_bmap_iextent(ip, &info, &irec);
+ memcpy(&info.prev_rec, &irec, sizeof(struct xfs_bmbt_irec));
+ }
+
+ if (xchk_bmap_want_check_rmaps(&info)) {
+ error = xchk_bmap_check_rmaps(sc, whichfork);
+ if (!xchk_fblock_xref_process_error(sc, whichfork, 0, &error))
+ return error;
+ }
+
+ return 0;
+}
+
+/* Scrub an inode's data fork. */
+int
+xchk_bmap_data(
+ struct xfs_scrub *sc)
+{
+ return xchk_bmap(sc, XFS_DATA_FORK);
+}
+
+/* Scrub an inode's attr fork. */
+int
+xchk_bmap_attr(
+ struct xfs_scrub *sc)
+{
+ return xchk_bmap(sc, XFS_ATTR_FORK);
+}
+
+/* Scrub an inode's CoW fork. */
+int
+xchk_bmap_cow(
+ struct xfs_scrub *sc)
+{
+ return xchk_bmap(sc, XFS_COW_FORK);
+}