xfs: check record domain when accessing refcount records

Now that we've separated the startblock and CoW/shared extent domain in
the incore refcount record structure, check the domain whenever we
retrieve a record to ensure that it's still in the domain that we want.
Depending on the circumstances, a change in domain either means we're
done processing or that we've found a corruption and need to fail out.

The refcount check in xchk_xref_is_cow_staging is redundant since
_get_rec has done that for a long time now, so we can get rid of it.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Dave Chinner <dchinner@redhat.com>

fs/xfs/libxfs/xfs_refcount.c

@@ -381,6 +381,8 @@ xfs_refcount_split_extent(
 		error = -EFSCORRUPTED;
 		goto out_error;
 	}
+	if (rcext.rc_domain != domain)
+		return 0;
 	if (rcext.rc_startblock == agbno || xfs_refc_next(&rcext) <= agbno)
 		return 0;
 
@@ -432,6 +434,9 @@ xfs_refcount_merge_center_extents(
 	trace_xfs_refcount_merge_center_extents(cur->bc_mp,
 			cur->bc_ag.pag->pag_agno, left, center, right);
 
+	ASSERT(left->rc_domain == center->rc_domain);
+	ASSERT(right->rc_domain == center->rc_domain);
+
 	/*
 	 * Make sure the center and right extents are not in the btree.
 	 * If the center extent was synthesized, the first delete call
@@ -508,6 +513,8 @@ xfs_refcount_merge_left_extent(
 	trace_xfs_refcount_merge_left_extent(cur->bc_mp,
 			cur->bc_ag.pag->pag_agno, left, cleft);
 
+	ASSERT(left->rc_domain == cleft->rc_domain);
+
 	/* If the extent at agbno (cleft) wasn't synthesized, remove it. */
 	if (cleft->rc_refcount > 1) {
 		error = xfs_refcount_lookup_le(cur, cleft->rc_domain,
@@ -569,6 +576,8 @@ xfs_refcount_merge_right_extent(
 	trace_xfs_refcount_merge_right_extent(cur->bc_mp,
 			cur->bc_ag.pag->pag_agno, cright, right);
 
+	ASSERT(right->rc_domain == cright->rc_domain);
+
 	/*
 	 * If the extent ending at agbno+aglen (cright) wasn't synthesized,
 	 * remove it.
@@ -649,11 +658,9 @@ xfs_refcount_find_left_extents(
 		goto out_error;
 	}
 
-	if (xfs_refc_next(&tmp) != agbno)
-		return 0;
-	if (domain == XFS_REFC_DOMAIN_SHARED && tmp.rc_refcount < 2)
+	if (tmp.rc_domain != domain)
 		return 0;
-	if (domain == XFS_REFC_DOMAIN_COW && tmp.rc_refcount > 1)
+	if (xfs_refc_next(&tmp) != agbno)
 		return 0;
 	/* We have a left extent; retrieve (or invent) the next right one */
 	*left = tmp;
@@ -670,6 +677,9 @@ xfs_refcount_find_left_extents(
 			goto out_error;
 		}
 
+		if (tmp.rc_domain != domain)
+			goto not_found;
+
 		/* if tmp starts at the end of our range, just use that */
 		if (tmp.rc_startblock == agbno)
 			*cleft = tmp;
@@ -689,6 +699,7 @@ xfs_refcount_find_left_extents(
 			cleft->rc_domain = domain;
 		}
 	} else {
+not_found:
 		/*
 		 * No extents, so pretend that there's one covering the whole
 		 * range.
@@ -740,11 +751,9 @@ xfs_refcount_find_right_extents(
 		goto out_error;
 	}
 
-	if (tmp.rc_startblock != agbno + aglen)
-		return 0;
-	if (domain == XFS_REFC_DOMAIN_SHARED && tmp.rc_refcount < 2)
+	if (tmp.rc_domain != domain)
 		return 0;
-	if (domain == XFS_REFC_DOMAIN_COW && tmp.rc_refcount > 1)
+	if (tmp.rc_startblock != agbno + aglen)
 		return 0;
 	/* We have a right extent; retrieve (or invent) the next left one */
 	*right = tmp;
@@ -761,6 +770,9 @@ xfs_refcount_find_right_extents(
 			goto out_error;
 		}
 
+		if (tmp.rc_domain != domain)
+			goto not_found;
+
 		/* if tmp ends at the end of our range, just use that */
 		if (xfs_refc_next(&tmp) == agbno + aglen)
 			*cright = tmp;
@@ -780,6 +792,7 @@ xfs_refcount_find_right_extents(
 			cright->rc_domain = domain;
 		}
 	} else {
+not_found:
 		/*
 		 * No extents, so pretend that there's one covering the whole
 		 * range.
@@ -889,7 +902,7 @@ xfs_refcount_merge_extents(
 				aglen);
 	}
 
-	return error;
+	return 0;
 }
 
 /*
@@ -961,7 +974,7 @@ xfs_refcount_adjust_extents(
 		error = xfs_refcount_get_rec(cur, &ext, &found_rec);
 		if (error)
 			goto out_error;
-		if (!found_rec) {
+		if (!found_rec || ext.rc_domain != XFS_REFC_DOMAIN_SHARED) {
 			ext.rc_startblock = cur->bc_mp->m_sb.sb_agblocks;
 			ext.rc_blockcount = 0;
 			ext.rc_refcount = 0;
@@ -1400,6 +1413,8 @@ xfs_refcount_find_shared(
 		error = -EFSCORRUPTED;
 		goto out_error;
 	}
+	if (tmp.rc_domain != XFS_REFC_DOMAIN_SHARED)
+		goto done;
 
 	/* If the extent ends before the start, look at the next one */
 	if (tmp.rc_startblock + tmp.rc_blockcount <= agbno) {
@@ -1415,6 +1430,8 @@ xfs_refcount_find_shared(
 			error = -EFSCORRUPTED;
 			goto out_error;
 		}
+		if (tmp.rc_domain != XFS_REFC_DOMAIN_SHARED)
+			goto done;
 	}
 
 	/* If the extent starts after the range we want, bail out */
@@ -1446,7 +1463,8 @@ xfs_refcount_find_shared(
 			error = -EFSCORRUPTED;
 			goto out_error;
 		}
-		if (tmp.rc_startblock >= agbno + aglen ||
+		if (tmp.rc_domain != XFS_REFC_DOMAIN_SHARED ||
+		    tmp.rc_startblock >= agbno + aglen ||
 		    tmp.rc_startblock != *fbno + *flen)
 			break;
 		*flen = min(*flen + tmp.rc_blockcount, agbno + aglen - *fbno);
@@ -1537,6 +1555,11 @@ xfs_refcount_adjust_cow_extents(
 	error = xfs_refcount_get_rec(cur, &ext, &found_rec);
 	if (error)
 		goto out_error;
+	if (XFS_IS_CORRUPT(cur->bc_mp, found_rec &&
+				ext.rc_domain != XFS_REFC_DOMAIN_COW)) {
+		error = -EFSCORRUPTED;
+		goto out_error;
+	}
 	if (!found_rec) {
 		ext.rc_startblock = cur->bc_mp->m_sb.sb_agblocks;
 		ext.rc_blockcount = 0;
@@ -1746,8 +1769,14 @@ xfs_refcount_recover_extent(
 
 	rr = kmem_alloc(sizeof(struct xfs_refcount_recovery), 0);
 	xfs_refcount_btrec_to_irec(rec, &rr->rr_rrec);
-	list_add_tail(&rr->rr_list, debris);
 
+	if (XFS_IS_CORRUPT(cur->bc_mp,
+			   rr->rr_rrec.rc_domain != XFS_REFC_DOMAIN_COW)) {
+		kmem_free(rr);
+		return -EFSCORRUPTED;
+	}
+
+	list_add_tail(&rr->rr_list, debris);
 	return 0;
 }
 

fs/xfs/scrub/refcount.c

@@ -439,8 +439,8 @@ xchk_xref_is_cow_staging(
 		return;
 	}
 
-	/* CoW flag must be set, refcount must be 1. */
-	if (rc.rc_domain != XFS_REFC_DOMAIN_COW || rc.rc_refcount != 1)
+	/* CoW lookup returned a shared extent record? */
+	if (rc.rc_domain != XFS_REFC_DOMAIN_COW)
 		xchk_btree_xref_set_corrupt(sc, sc->sa.refc_cur, 0);
 
 	/* Must be at least as long as what was passed in */