Merge tag 'repair-force-rebuild-6.6_2023-08-10' of https://git.kernel.org/pub/scm/linux/kernel/git/djwong/xfs-linux into xfs-6.6-mergeA

xfs: force rebuilding of metadata

This patchset adds a new IFLAG to the scrub ioctl so that userspace can
force a rebuild of an otherwise consistent piece of metadata.  This will
eventually enable the use of online repair to relocate metadata during a
filesystem reorganization (e.g. shrink).  For now, it facilitates stress
testing of online repair without needing the debugging knobs to be
enabled.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Chandan Babu R <chandan.babu@oracle.com>

* tag 'repair-force-rebuild-6.6_2023-08-10' of https://git.kernel.org/pub/scm/linux/kernel/git/djwong/xfs-linux:
  xfs: allow userspace to rebuild metadata structures
  xfs: don't complain about unfixed metadata when repairs were injected

Author: Chandan Babu R

fs/xfs/libxfs/xfs_fs.h

@@ -743,7 +743,11 @@ struct xfs_scrub_metadata {
  */
 #define XFS_SCRUB_OFLAG_NO_REPAIR_NEEDED (1u << 7)
 
-#define XFS_SCRUB_FLAGS_IN	(XFS_SCRUB_IFLAG_REPAIR)
+/* i: Rebuild the data structure. */
+#define XFS_SCRUB_IFLAG_FORCE_REBUILD	(1u << 8)
+
+#define XFS_SCRUB_FLAGS_IN	(XFS_SCRUB_IFLAG_REPAIR | \
+				 XFS_SCRUB_IFLAG_FORCE_REBUILD)
 #define XFS_SCRUB_FLAGS_OUT	(XFS_SCRUB_OFLAG_CORRUPT | \
 				 XFS_SCRUB_OFLAG_PREEN | \
 				 XFS_SCRUB_OFLAG_XFAIL | \

fs/xfs/scrub/common.h

@@ -167,6 +167,18 @@ static inline bool xchk_skip_xref(struct xfs_scrub_metadata *sm)
 			       XFS_SCRUB_OFLAG_XCORRUPT);
 }
 
+#ifdef CONFIG_XFS_ONLINE_REPAIR
+/* Decide if a repair is required. */
+static inline bool xchk_needs_repair(const struct xfs_scrub_metadata *sm)
+{
+	return sm->sm_flags & (XFS_SCRUB_OFLAG_CORRUPT |
+			       XFS_SCRUB_OFLAG_XCORRUPT |
+			       XFS_SCRUB_OFLAG_PREEN);
+}
+#else
+# define xchk_needs_repair(sc)		(false)
+#endif /* CONFIG_XFS_ONLINE_REPAIR */
+
 int xchk_metadata_inode_forks(struct xfs_scrub *sc);
 
 /*

fs/xfs/scrub/scrub.c

@@ -409,6 +409,11 @@ xchk_validate_inputs(
 		goto out;
 	}
 
+	/* No rebuild without repair. */
+	if ((sm->sm_flags & XFS_SCRUB_IFLAG_FORCE_REBUILD) &&
+	    !(sm->sm_flags & XFS_SCRUB_IFLAG_REPAIR))
+		return -EINVAL;
+
 	/*
 	 * We only want to repair read-write v5+ filesystems.  Defer the check
 	 * for ops->repair until after our scrub confirms that we need to
@@ -535,15 +540,16 @@ xfs_scrub_metadata(
 
 	if ((sc->sm->sm_flags & XFS_SCRUB_IFLAG_REPAIR) &&
 	    !(sc->flags & XREP_ALREADY_FIXED)) {
-		bool needs_fix;
+		bool needs_fix = xchk_needs_repair(sc->sm);
+
+		/* Userspace asked us to rebuild the structure regardless. */
+		if (sc->sm->sm_flags & XFS_SCRUB_IFLAG_FORCE_REBUILD)
+			needs_fix = true;
 
 		/* Let debug users force us into the repair routines. */
-		if (XFS_TEST_ERROR(false, mp, XFS_ERRTAG_FORCE_SCRUB_REPAIR))
-			sc->sm->sm_flags |= XFS_SCRUB_OFLAG_CORRUPT;
+		if (XFS_TEST_ERROR(needs_fix, mp, XFS_ERRTAG_FORCE_SCRUB_REPAIR))
+			needs_fix = true;
 
-		needs_fix = (sc->sm->sm_flags & (XFS_SCRUB_OFLAG_CORRUPT |
-						 XFS_SCRUB_OFLAG_XCORRUPT |
-						 XFS_SCRUB_OFLAG_PREEN));
 		/*
 		 * If userspace asked for a repair but it wasn't necessary,
 		 * report that back to userspace.

fs/xfs/scrub/trace.h

@@ -98,7 +98,8 @@ TRACE_DEFINE_ENUM(XFS_SCRUB_TYPE_FSCOUNTERS);
 	{ XFS_SCRUB_OFLAG_XCORRUPT,		"xcorrupt" }, \
 	{ XFS_SCRUB_OFLAG_INCOMPLETE,		"incomplete" }, \
 	{ XFS_SCRUB_OFLAG_WARNING,		"warning" }, \
-	{ XFS_SCRUB_OFLAG_NO_REPAIR_NEEDED,	"norepair" }
+	{ XFS_SCRUB_OFLAG_NO_REPAIR_NEEDED,	"norepair" }, \
+	{ XFS_SCRUB_IFLAG_FORCE_REBUILD,	"rebuild" }
 
 #define XFS_SCRUB_STATE_STRINGS \
 	{ XCHK_TRY_HARDER,			"try_harder" }, \