xfs: scrub rmap btrees

Check the reverse mapping records to make sure that the contents
make sense.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>

fs/xfs/Makefile

@@ -148,6 +148,7 @@ xfs-y				+= $(addprefix scrub/, \
 				   btree.o \
 				   common.o \
 				   ialloc.o \
+				   rmap.o \
 				   scrub.o \
 				   )
 endif

fs/xfs/libxfs/xfs_fs.h

@@ -492,9 +492,10 @@ struct xfs_scrub_metadata {
 #define XFS_SCRUB_TYPE_CNTBT	6	/* freesp by length btree */
 #define XFS_SCRUB_TYPE_INOBT	7	/* inode btree */
 #define XFS_SCRUB_TYPE_FINOBT	8	/* free inode btree */
+#define XFS_SCRUB_TYPE_RMAPBT	9	/* reverse mapping btree */
 
 /* Number of scrub subcommands. */
-#define XFS_SCRUB_TYPE_NR	9
+#define XFS_SCRUB_TYPE_NR	10
 
 /* i: Repair this metadata. */
 #define XFS_SCRUB_IFLAG_REPAIR		(1 << 0)

fs/xfs/scrub/common.h

@@ -83,6 +83,8 @@ int xfs_scrub_setup_ag_allocbt(struct xfs_scrub_context *sc,
 			       struct xfs_inode *ip);
 int xfs_scrub_setup_ag_iallocbt(struct xfs_scrub_context *sc,
 				struct xfs_inode *ip);
+int xfs_scrub_setup_ag_rmapbt(struct xfs_scrub_context *sc,
+			      struct xfs_inode *ip);
 
 
 void xfs_scrub_ag_free(struct xfs_scrub_context *sc, struct xfs_scrub_ag *sa);

fs/xfs/scrub/rmap.c

@@ -0,0 +1,138 @@
+/*
+ * Copyright (C) 2017 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_alloc.h"
+#include "xfs_ialloc.h"
+#include "xfs_rmap.h"
+#include "scrub/xfs_scrub.h"
+#include "scrub/scrub.h"
+#include "scrub/common.h"
+#include "scrub/btree.h"
+#include "scrub/trace.h"
+
+/*
+ * Set us up to scrub reverse mapping btrees.
+ */
+int
+xfs_scrub_setup_ag_rmapbt(
+	struct xfs_scrub_context	*sc,
+	struct xfs_inode		*ip)
+{
+	return xfs_scrub_setup_ag_btree(sc, ip, false);
+}
+
+/* Reverse-mapping scrubber. */
+
+/* Scrub an rmapbt record. */
+STATIC int
+xfs_scrub_rmapbt_rec(
+	struct xfs_scrub_btree		*bs,
+	union xfs_btree_rec		*rec)
+{
+	struct xfs_mount		*mp = bs->cur->bc_mp;
+	struct xfs_rmap_irec		irec;
+	xfs_agnumber_t			agno = bs->cur->bc_private.a.agno;
+	bool				non_inode;
+	bool				is_unwritten;
+	bool				is_bmbt;
+	bool				is_attr;
+	int				error;
+
+	error = xfs_rmap_btrec_to_irec(rec, &irec);
+	if (!xfs_scrub_btree_process_error(bs->sc, bs->cur, 0, &error))
+		goto out;
+
+	/* Check extent. */
+	if (irec.rm_startblock + irec.rm_blockcount <= irec.rm_startblock)
+		xfs_scrub_btree_set_corrupt(bs->sc, bs->cur, 0);
+
+	if (irec.rm_owner == XFS_RMAP_OWN_FS) {
+		/*
+		 * xfs_verify_agbno returns false for static fs metadata.
+		 * Since that only exists at the start of the AG, validate
+		 * that by hand.
+		 */
+		if (irec.rm_startblock != 0 ||
+		    irec.rm_blockcount != XFS_AGFL_BLOCK(mp) + 1)
+			xfs_scrub_btree_set_corrupt(bs->sc, bs->cur, 0);
+	} else {
+		/*
+		 * Otherwise we must point somewhere past the static metadata
+		 * but before the end of the FS.  Run the regular check.
+		 */
+		if (!xfs_verify_agbno(mp, agno, irec.rm_startblock) ||
+		    !xfs_verify_agbno(mp, agno, irec.rm_startblock +
+				irec.rm_blockcount - 1))
+			xfs_scrub_btree_set_corrupt(bs->sc, bs->cur, 0);
+	}
+
+	/* Check flags. */
+	non_inode = XFS_RMAP_NON_INODE_OWNER(irec.rm_owner);
+	is_bmbt = irec.rm_flags & XFS_RMAP_BMBT_BLOCK;
+	is_attr = irec.rm_flags & XFS_RMAP_ATTR_FORK;
+	is_unwritten = irec.rm_flags & XFS_RMAP_UNWRITTEN;
+
+	if (is_bmbt && irec.rm_offset != 0)
+		xfs_scrub_btree_set_corrupt(bs->sc, bs->cur, 0);
+
+	if (non_inode && irec.rm_offset != 0)
+		xfs_scrub_btree_set_corrupt(bs->sc, bs->cur, 0);
+
+	if (is_unwritten && (is_bmbt || non_inode || is_attr))
+		xfs_scrub_btree_set_corrupt(bs->sc, bs->cur, 0);
+
+	if (non_inode && (is_bmbt || is_unwritten || is_attr))
+		xfs_scrub_btree_set_corrupt(bs->sc, bs->cur, 0);
+
+	if (!non_inode) {
+		if (!xfs_verify_ino(mp, irec.rm_owner))
+			xfs_scrub_btree_set_corrupt(bs->sc, bs->cur, 0);
+	} else {
+		/* Non-inode owner within the magic values? */
+		if (irec.rm_owner <= XFS_RMAP_OWN_MIN ||
+		    irec.rm_owner > XFS_RMAP_OWN_FS)
+			xfs_scrub_btree_set_corrupt(bs->sc, bs->cur, 0);
+	}
+out:
+	return error;
+}
+
+/* Scrub the rmap btree for some AG. */
+int
+xfs_scrub_rmapbt(
+	struct xfs_scrub_context	*sc)
+{
+	struct xfs_owner_info		oinfo;
+
+	xfs_rmap_ag_owner(&oinfo, XFS_RMAP_OWN_AG);
+	return xfs_scrub_btree(sc, sc->sa.rmap_cur, xfs_scrub_rmapbt_rec,
+			&oinfo, NULL);
+}

fs/xfs/scrub/scrub.c

@@ -191,6 +191,11 @@ static const struct xfs_scrub_meta_ops meta_scrub_ops[] = {
 		.scrub	= xfs_scrub_finobt,
 		.has	= xfs_sb_version_hasfinobt,
 	},
+	{ /* rmapbt */
+		.setup	= xfs_scrub_setup_ag_rmapbt,
+		.scrub	= xfs_scrub_rmapbt,
+		.has	= xfs_sb_version_hasrmapbt,
+	},
 };
 
 /* This isn't a stable feature, warn once per day. */

fs/xfs/scrub/scrub.h

@@ -75,5 +75,6 @@ int xfs_scrub_bnobt(struct xfs_scrub_context *sc);
 int xfs_scrub_cntbt(struct xfs_scrub_context *sc);
 int xfs_scrub_inobt(struct xfs_scrub_context *sc);
 int xfs_scrub_finobt(struct xfs_scrub_context *sc);
+int xfs_scrub_rmapbt(struct xfs_scrub_context *sc);
 
 #endif	/* __XFS_SCRUB_SCRUB_H__ */