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 <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>

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 	/* Exact match, scan data is out of date.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__ */

fs/xfs/scrub/orphanage.c

@@ -570,6 +570,12 @@ xrep_adoption_move(
 		xfs_bumplink(sc->tp, sc->orphanage);
 	xfs_trans_log_inode(sc->tp, sc->orphanage, XFS_ILOG_CORE);
 
+	/* Bump the link count of the child. */
+	if (adopt->bump_child_nlink) {
+		xfs_bumplink(sc->tp, sc->ip);
+		xfs_trans_log_inode(sc->tp, sc->ip, XFS_ILOG_CORE);
+	}
+
 	/* Replace the dotdot entry if the child is a subdirectory. */
 	if (isdir) {
 		error = xfs_dir_replace(sc->tp, sc->ip, &xfs_name_dotdot,

fs/xfs/scrub/orphanage.h

@@ -60,6 +60,14 @@ struct xrep_adoption {
 	/* Block reservations for orphanage and child (if directory). */
 	unsigned int		orphanage_blkres;
 	unsigned int		child_blkres;
+
+	/*
+	 * Does the caller want us to bump the child link count?  This is not
+	 * needed when reattaching files that have become disconnected but have
+	 * nlink > 1.  It is necessary when changing the directory tree
+	 * structure.
+	 */
+	bool			bump_child_nlink:1;
 };
 
 bool xrep_orphanage_can_adopt(struct xfs_scrub *sc);

fs/xfs/scrub/repair.h

@@ -95,6 +95,7 @@ int xrep_setup_directory(struct xfs_scrub *sc);
 int xrep_setup_parent(struct xfs_scrub *sc);
 int xrep_setup_nlinks(struct xfs_scrub *sc);
 int xrep_setup_symlink(struct xfs_scrub *sc, unsigned int *resblks);
+int xrep_setup_dirtree(struct xfs_scrub *sc);
 
 /* Repair setup functions */
 int xrep_setup_ag_allocbt(struct xfs_scrub *sc);
@@ -132,6 +133,7 @@ int xrep_xattr(struct xfs_scrub *sc);
 int xrep_directory(struct xfs_scrub *sc);
 int xrep_parent(struct xfs_scrub *sc);
 int xrep_symlink(struct xfs_scrub *sc);
+int xrep_dirtree(struct xfs_scrub *sc);
 
 #ifdef CONFIG_XFS_RT
 int xrep_rtbitmap(struct xfs_scrub *sc);
@@ -205,6 +207,7 @@ xrep_setup_nothing(
 #define xrep_setup_directory		xrep_setup_nothing
 #define xrep_setup_parent		xrep_setup_nothing
 #define xrep_setup_nlinks		xrep_setup_nothing
+#define xrep_setup_dirtree		xrep_setup_nothing
 
 #define xrep_setup_inode(sc, imap)	((void)0)
 
@@ -239,6 +242,7 @@ static inline int xrep_setup_symlink(struct xfs_scrub *sc, unsigned int *x)
 #define xrep_directory			xrep_notsupported
 #define xrep_parent			xrep_notsupported
 #define xrep_symlink			xrep_notsupported
+#define xrep_dirtree			xrep_notsupported
 
 #endif /* CONFIG_XFS_ONLINE_REPAIR */
 

fs/xfs/scrub/scrub.c

@@ -441,7 +441,7 @@ static const struct xchk_meta_ops meta_scrub_ops[] = {
 		.setup	= xchk_setup_dirtree,
 		.scrub	= xchk_dirtree,
 		.has	= xfs_has_parent,
-		.repair	= xrep_notsupported,
+		.repair	= xrep_dirtree,
 	},
 };
 

fs/xfs/scrub/trace.h

@@ -1685,6 +1685,10 @@ TRACE_DEFINE_ENUM(XCHK_DIRPATH_CORRUPT);
 TRACE_DEFINE_ENUM(XCHK_DIRPATH_LOOP);
 TRACE_DEFINE_ENUM(XCHK_DIRPATH_STALE);
 TRACE_DEFINE_ENUM(XCHK_DIRPATH_OK);
+TRACE_DEFINE_ENUM(XREP_DIRPATH_DELETING);
+TRACE_DEFINE_ENUM(XREP_DIRPATH_DELETED);
+TRACE_DEFINE_ENUM(XREP_DIRPATH_ADOPTING);
+TRACE_DEFINE_ENUM(XREP_DIRPATH_ADOPTED);
 
 #define XCHK_DIRPATH_OUTCOME_STRINGS \
 	{ XCHK_DIRPATH_SCANNING,	"scanning" }, \
@@ -1692,7 +1696,11 @@ TRACE_DEFINE_ENUM(XCHK_DIRPATH_OK);
 	{ XCHK_DIRPATH_CORRUPT,		"corrupt" }, \
 	{ XCHK_DIRPATH_LOOP,		"loop" }, \
 	{ XCHK_DIRPATH_STALE,		"stale" }, \
-	{ XCHK_DIRPATH_OK,		"ok" }
+	{ XCHK_DIRPATH_OK,		"ok" }, \
+	{ XREP_DIRPATH_DELETING,	"deleting" }, \
+	{ XREP_DIRPATH_DELETED,		"deleted" }, \
+	{ XREP_DIRPATH_ADOPTING,	"adopting" }, \
+	{ XREP_DIRPATH_ADOPTED,		"adopted" }
 
 DECLARE_EVENT_CLASS(xchk_dirpath_outcome_class,
 	TP_PROTO(struct xfs_scrub *sc, unsigned long long path_nr,
@@ -1738,6 +1746,7 @@ DECLARE_EVENT_CLASS(xchk_dirtree_evaluate_class,
 		__field(unsigned int, bad)
 		__field(unsigned int, suspect)
 		__field(unsigned int, good)
+		__field(bool, needs_adoption)
 	),
 	TP_fast_assign(
 		__entry->dev = dl->sc->mp->m_super->s_dev;
@@ -1747,15 +1756,17 @@ DECLARE_EVENT_CLASS(xchk_dirtree_evaluate_class,
 		__entry->bad = oc->bad;
 		__entry->suspect = oc->suspect;
 		__entry->good = oc->good;
+		__entry->needs_adoption = oc->needs_adoption ? 1 : 0;
 	),
-	TP_printk("dev %d:%d ino 0x%llx rootino 0x%llx nr_paths %u bad %u suspect %u good %u",
+	TP_printk("dev %d:%d ino 0x%llx rootino 0x%llx nr_paths %u bad %u suspect %u good %u adopt? %d",
 		  MAJOR(__entry->dev), MINOR(__entry->dev),
 		  __entry->ino,
 		  __entry->rootino,
 		  __entry->nr_paths,
 		  __entry->bad,
 		  __entry->suspect,
-		  __entry->good)
+		  __entry->good,
+		  __entry->needs_adoption)
 );
 #define DEFINE_XCHK_DIRTREE_EVALUATE_EVENT(name) \
 DEFINE_EVENT(xchk_dirtree_evaluate_class, name, \
@@ -3181,6 +3192,7 @@ DEFINE_REPAIR_DENTRY_EVENT(xrep_adoption_check_child);
 DEFINE_REPAIR_DENTRY_EVENT(xrep_adoption_check_alias);
 DEFINE_REPAIR_DENTRY_EVENT(xrep_adoption_check_dentry);
 DEFINE_REPAIR_DENTRY_EVENT(xrep_adoption_invalidate_child);
+DEFINE_REPAIR_DENTRY_EVENT(xrep_dirtree_delete_child);
 
 TRACE_EVENT(xrep_symlink_salvage_target,
 	TP_PROTO(struct xfs_inode *ip, char *target, unsigned int targetlen),
@@ -3483,6 +3495,11 @@ TRACE_EVENT(xrep_iunlink_commit_bucket,
 		  __entry->agino)
 );
 
+DEFINE_XCHK_DIRPATH_OUTCOME_EVENT(xrep_dirpath_set_outcome);
+DEFINE_XCHK_DIRTREE_EVENT(xrep_dirtree_delete_path);
+DEFINE_XCHK_DIRTREE_EVENT(xrep_dirtree_create_adoption);
+DEFINE_XCHK_DIRTREE_EVALUATE_EVENT(xrep_dirtree_decided_fate);
+
 #endif /* IS_ENABLED(CONFIG_XFS_ONLINE_REPAIR) */
 
 #endif /* _TRACE_XFS_SCRUB_TRACE_H */

fs/xfs/xfs_inode.c

@@ -893,7 +893,7 @@ xfs_init_new_inode(
  * link count to go to zero, move the inode to AGI unlinked list so that it can
  * be freed when the last active reference goes away via xfs_inactive().
  */
-static int			/* error */
+int
 xfs_droplink(
 	struct xfs_trans	*tp,
 	struct xfs_inode	*ip)

fs/xfs/xfs_inode.h

@@ -626,6 +626,7 @@ void xfs_end_io(struct work_struct *work);
 int xfs_ilock2_io_mmap(struct xfs_inode *ip1, struct xfs_inode *ip2);
 void xfs_iunlock2_io_mmap(struct xfs_inode *ip1, struct xfs_inode *ip2);
 void xfs_iunlock2_remapping(struct xfs_inode *ip1, struct xfs_inode *ip2);
+int xfs_droplink(struct xfs_trans *tp, struct xfs_inode *ip);
 void xfs_bumplink(struct xfs_trans *tp, struct xfs_inode *ip);
 void xfs_lock_inodes(struct xfs_inode **ips, int inodes, uint lock_mode);
 void xfs_sort_inodes(struct xfs_inode **i_tab, unsigned int num_inodes);