xfs: fix corruptions in the directory tree

Repair corruptions in the directory tree itself.  Cycles are broken by
removing an incoming parent->child link.  Multiply-owned directories are
fixed by pruning the extra parent -> child links  Disconnected subtrees
are reconnected to the lost and found.

Signed-off-by: Darrick J. Wong <[email protected]>
Reviewed-by: Christoph Hellwig <[email protected]>

Author: Darrick J. Wong

fs/xfs/Makefile

@@ -204,6 +204,7 @@ xfs-y				+= $(addprefix scrub/, \
 				   bmap_repair.o \
 				   cow_repair.o \
 				   dir_repair.o \
+				   dirtree_repair.o \
 				   findparent.o \
 				   fscounters_repair.o \
 				   ialloc_repair.o \

fs/xfs/scrub/dirtree.c

@@ -26,6 +26,8 @@
 #include "scrub/xfblob.h"
 #include "scrub/listxattr.h"
 #include "scrub/trace.h"
+#include "scrub/repair.h"
+#include "scrub/orphanage.h"
 #include "scrub/dirtree.h"
 
 /*
@@ -95,6 +97,12 @@ xchk_setup_dirtree(
 
 	xchk_fsgates_enable(sc, XCHK_FSGATES_DIRENTS);
 
+	if (xchk_could_repair(sc)) {
+		error = xrep_setup_dirtree(sc);
+		if (error)
+			return error;
+	}
+
 	dl = kvzalloc(sizeof(struct xchk_dirtree), XCHK_GFP_FLAGS);
 	if (!dl)
 		return -ENOMEM;
@@ -104,6 +112,7 @@ xchk_setup_dirtree(
 	INIT_LIST_HEAD(&dl->path_list);
 	dl->root_ino = NULLFSINO;
 	dl->scan_ino = NULLFSINO;
+	dl->parent_ino = NULLFSINO;
 
 	mutex_init(&dl->lock);
 
@@ -142,7 +151,7 @@ xchk_setup_dirtree(
  * Add the parent pointer described by @dl->pptr to the given path as a new
  * step.  Returns -ELNRNG if the path is too deep.
  */
-STATIC int
+int
 xchk_dirpath_append(
 	struct xchk_dirtree		*dl,
 	struct xfs_inode		*ip,
@@ -609,6 +618,22 @@ xchk_dirpath_step_is_stale(
 	if (memcmp(dl->hook_xname.name, p->name->name, p->name->len) != 0)
 		return 0;
 
+	/*
+	 * If the update comes from the repair code itself, walk the state
+	 * machine forward.
+	 */
+	if (p->ip->i_ino == dl->scan_ino &&
+	    path->outcome == XREP_DIRPATH_ADOPTING) {
+		xchk_dirpath_set_outcome(dl, path, XREP_DIRPATH_ADOPTED);
+		return 0;
+	}
+
+	if (p->ip->i_ino == dl->scan_ino &&
+	    path->outcome == XREP_DIRPATH_DELETING) {
+		xchk_dirpath_set_outcome(dl, path, XREP_DIRPATH_DELETED);
+		return 0;
+	}
+
 	/* Exact match, scan data is out of date. */
 	trace_xchk_dirpath_changed(dl->sc, path->path_nr, step_nr, p->dp,
 			p->ip, p->name);
@@ -747,7 +772,7 @@ xchk_dirtree_load_path(
  * path was too deep; -ENOSR if there were too many parent pointers; or
  * a negative errno.
  */
-STATIC int
+int
 xchk_dirtree_find_paths_to_root(
 	struct xchk_dirtree	*dl)
 {
@@ -819,7 +844,7 @@ xchk_dirtree_find_paths_to_root(
  * Figure out what to do with the paths we tried to find.  Do not call this
  * if the scan results are stale.
  */
-STATIC void
+void
 xchk_dirtree_evaluate(
 	struct xchk_dirtree		*dl,
 	struct xchk_dirtree_outcomes	*oc)
@@ -856,6 +881,13 @@ xchk_dirtree_evaluate(
 			/* This path got all the way to the root. */
 			oc->good++;
 			break;
+		case XREP_DIRPATH_DELETING:
+		case XREP_DIRPATH_DELETED:
+		case XREP_DIRPATH_ADOPTING:
+		case XREP_DIRPATH_ADOPTED:
+			/* These should not be in progress! */
+			ASSERT(0);
+			break;
 		}
 	}
 

fs/xfs/scrub/dirtree.h

@@ -26,6 +26,11 @@ enum xchk_dirpath_outcome {
 	XCHK_DIRPATH_LOOP,		/* cycle detected further up */
 	XCHK_DIRPATH_STALE,		/* path is stale */
 	XCHK_DIRPATH_OK,		/* path reaches the root */
+
+	XREP_DIRPATH_DELETING,		/* path is being deleted */
+	XREP_DIRPATH_DELETED,		/* path has been deleted */
+	XREP_DIRPATH_ADOPTING,		/* path is being adopted */
+	XREP_DIRPATH_ADOPTED,		/* path has been adopted */
 };
 
 /*
@@ -64,6 +69,9 @@ struct xchk_dirtree_outcomes {
 
 	/* Number of XCHK_DIRPATH_OK */
 	unsigned int		good;
+
+	/* Directory needs to be added to lost+found */
+	bool			needs_adoption;
 };
 
 struct xchk_dirtree {
@@ -79,6 +87,14 @@ struct xchk_dirtree {
 	 */
 	xfs_ino_t		scan_ino;
 
+	/*
+	 * If we start deleting redundant paths to this subdirectory, this is
+	 * the inode number of the surviving parent and the dotdot entry will
+	 * be set to this value.  If the value is NULLFSINO, then use @root_ino
+	 * as a stand-in until the orphanage can adopt the subdirectory.
+	 */
+	xfs_ino_t		parent_ino;
+
 	/* Scratch buffer for scanning pptr xattrs */
 	struct xfs_parent_rec	pptr_rec;
 	struct xfs_da_args	pptr_args;
@@ -87,12 +103,18 @@ struct xchk_dirtree {
 	struct xfs_name		xname;
 	char			namebuf[MAXNAMELEN];
 
+	/* Information for reparenting this directory. */
+	struct xrep_adoption	adoption;
+
 	/*
 	 * Hook into directory updates so that we can receive live updates
 	 * from other writer threads.
 	 */
 	struct xfs_dir_hook	dhook;
 
+	/* Parent pointer update arguments. */
+	struct xfs_parent_args	ppargs;
+
 	/* lock for everything below here */
 	struct mutex		lock;
 
@@ -146,4 +168,11 @@ xchk_dirtree_parentless(const struct xchk_dirtree *dl)
 	return false;
 }
 
+int xchk_dirtree_find_paths_to_root(struct xchk_dirtree *dl);
+int xchk_dirpath_append(struct xchk_dirtree *dl, struct xfs_inode *ip,
+		struct xchk_dirpath *path, const struct xfs_name *name,
+		const struct xfs_parent_rec *pptr);
+void xchk_dirtree_evaluate(struct xchk_dirtree *dl,
+		struct xchk_dirtree_outcomes *oc);
+
 #endif /* __XFS_SCRUB_DIRTREE_H__ */