@@ -836,3 +836,193 @@ xfs_repair_reap_btree_extents(
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;
+}
@@ -77,6 +77,26 @@ 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_find_ag_btree {
+ /* in: rmap owner of the btree we're looking for */
+ uint64_t rmap_owner;
+
+ /* in: buffer ops */
+ const struct xfs_buf_ops *buf_ops;
+
+ /* in: magic number of the btree */
+ uint32_t magic;
+
+ /* out: the highest btree block found and the tree height */
+ xfs_agblock_t root;
+ unsigned int height;
+};
+
+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);
+
/* Metadata repairers */
int xfs_repair_probe(struct xfs_scrub_context *sc);