Merge tag 'scrub-directory-tree-6.10_2024-04-23' of...

Merge tag 'scrub-directory-tree-6.10_2024-04-23' of https://git.kernel.org/pub/scm/linux/kernel/git/djwong/xfs-linux into xfs-6.10-mergeC

xfs: detect and correct directory tree problems

Historically, checking the tree-ness of the directory tree structure has
not been complete.  Cycles of subdirectories break the tree properties,
as do subdirectories with multiple parents.  It's easy enough for DFS to
detect problems as long as one of the participants is reachable from the
root, but this technique cannot find unconnected cycles.

Directory parent pointers change that, because we can discover all of
these problems from a simple walk from a subdirectory towards the root.
For each child we start with, if the walk terminates without reaching
the root, we know the path is disconnected and ought to be attached to
the lost and found.  If we find ourselves, we know this is a cycle and
can delete an incoming edge.  If we find multiple paths to the root, we
know to delete an incoming edge.

Even better, once we've finished walking paths, we've identified the
good ones and know which other path(s) to remove.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Chandan Babu R <chandanbabu@kernel.org>

* tag 'scrub-directory-tree-6.10_2024-04-23' of https://git.kernel.org/pub/scm/linux/kernel/git/djwong/xfs-linux:
  xfs: fix corruptions in the directory tree
  xfs: report directory tree corruption in the health information
  xfs: invalidate dirloop scrub path data when concurrent updates happen
  xfs: teach online scrub to find directory tree structure problems

fs/xfs/Makefile

@@ -163,6 +163,7 @@ xfs-y				+= $(addprefix scrub/, \
 				   common.o \
 				   dabtree.o \
 				   dir.o \
+				   dirtree.o \
 				   fscounters.o \
 				   health.o \
 				   ialloc.o \
@@ -203,6 +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/libxfs/xfs_fs.h

@@ -411,6 +411,7 @@ struct xfs_bulkstat {
 #define XFS_BS_SICK_XATTR	(1 << 5)  /* extended attributes */
 #define XFS_BS_SICK_SYMLINK	(1 << 6)  /* symbolic link remote target */
 #define XFS_BS_SICK_PARENT	(1 << 7)  /* parent pointers */
+#define XFS_BS_SICK_DIRTREE	(1 << 8)  /* directory tree structure */
 
 /*
  * Project quota id helpers (previously projid was 16bit only
@@ -719,9 +720,10 @@ struct xfs_scrub_metadata {
 #define XFS_SCRUB_TYPE_QUOTACHECK 25	/* quota counters */
 #define XFS_SCRUB_TYPE_NLINKS	26	/* inode link counts */
 #define XFS_SCRUB_TYPE_HEALTHY	27	/* everything checked out ok */
+#define XFS_SCRUB_TYPE_DIRTREE	28	/* directory tree structure */
 
 /* Number of scrub subcommands. */
-#define XFS_SCRUB_TYPE_NR	28
+#define XFS_SCRUB_TYPE_NR	29
 
 /* i: Repair this metadata. */
 #define XFS_SCRUB_IFLAG_REPAIR		(1u << 0)

fs/xfs/libxfs/xfs_health.h

@@ -95,6 +95,7 @@ struct xfs_da_args;
 
 /* Don't propagate sick status to ag health summary during inactivation */
 #define XFS_SICK_INO_FORGET	(1 << 12)
+#define XFS_SICK_INO_DIRTREE	(1 << 13)  /* directory tree structure */
 
 /* Primary evidence of health problems in a given group. */
 #define XFS_SICK_FS_PRIMARY	(XFS_SICK_FS_COUNTERS | \
@@ -125,7 +126,8 @@ struct xfs_da_args;
 				 XFS_SICK_INO_DIR | \
 				 XFS_SICK_INO_XATTR | \
 				 XFS_SICK_INO_SYMLINK | \
-				 XFS_SICK_INO_PARENT)
+				 XFS_SICK_INO_PARENT | \
+				 XFS_SICK_INO_DIRTREE)
 
 #define XFS_SICK_INO_ZAPPED	(XFS_SICK_INO_BMBTD_ZAPPED | \
 				 XFS_SICK_INO_BMBTA_ZAPPED | \

fs/xfs/scrub/common.h

@@ -92,6 +92,7 @@ int xchk_setup_directory(struct xfs_scrub *sc);
 int xchk_setup_xattr(struct xfs_scrub *sc);
 int xchk_setup_symlink(struct xfs_scrub *sc);
 int xchk_setup_parent(struct xfs_scrub *sc);
+int xchk_setup_dirtree(struct xfs_scrub *sc);
 #ifdef CONFIG_XFS_RT
 int xchk_setup_rtbitmap(struct xfs_scrub *sc);
 int xchk_setup_rtsummary(struct xfs_scrub *sc);

fs/xfs/scrub/dirtree.h

+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * Copyright (c) 2023-2024 Oracle.  All Rights Reserved.
+ * Author: Darrick J. Wong <djwong@kernel.org>
+ */
+#ifndef __XFS_SCRUB_DIRTREE_H__
+#define __XFS_SCRUB_DIRTREE_H__
+
+/*
+ * Each of these represents one parent pointer path step in a chain going
+ * up towards the directory tree root.  These are stored inside an xfarray.
+ */
+struct xchk_dirpath_step {
+	/* Directory entry name associated with this parent link. */
+	xfblob_cookie		name_cookie;
+	unsigned int		name_len;
+
+	/* Handle of the parent directory. */
+	struct xfs_parent_rec	pptr_rec;
+};
+
+enum xchk_dirpath_outcome {
+	XCHK_DIRPATH_SCANNING = 0,	/* still being put together */
+	XCHK_DIRPATH_DELETE,		/* delete this path */
+	XCHK_DIRPATH_CORRUPT,		/* corruption detected in path */
+	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 */
+};
+
+/*
+ * Each of these represents one parent pointer path out of the directory being
+ * scanned.  These exist in-core, and hopefully there aren't more than a
+ * handful of them.
+ */
+struct xchk_dirpath {
+	struct list_head	list;
+
+	/* Index of the first step in this path. */
+	xfarray_idx_t		first_step;
+
+	/* Index of the second step in this path. */
+	xfarray_idx_t		second_step;
+
+	/* Inodes seen while walking this path. */
+	struct xino_bitmap	seen_inodes;
+
+	/* Number of steps in this path. */
+	unsigned int		nr_steps;
+
+	/* Which path is this? */
+	unsigned int		path_nr;
+
+	/* What did we conclude from following this path? */
+	enum xchk_dirpath_outcome outcome;
+};
+
+struct xchk_dirtree_outcomes {
+	/* Number of XCHK_DIRPATH_DELETE */
+	unsigned int		bad;
+
+	/* Number of XCHK_DIRPATH_CORRUPT or XCHK_DIRPATH_LOOP */
+	unsigned int		suspect;
+
+	/* Number of XCHK_DIRPATH_OK */
+	unsigned int		good;
+
+	/* Directory needs to be added to lost+found */
+	bool			needs_adoption;
+};
+
+struct xchk_dirtree {
+	struct xfs_scrub	*sc;
+
+	/* Root inode that we're looking for. */
+	xfs_ino_t		root_ino;
+
+	/*
+	 * This is the inode that we're scanning.  The live update hook can
+	 * continue to be called after xchk_teardown drops sc->ip but before
+	 * it calls buf_cleanup, so we keep a copy.
+	 */
+	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;
+
+	/* Name buffer */
+	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;
+
+	/* buffer for the live update functions to use for dirent names */
+	struct xfs_name		hook_xname;
+	unsigned char		hook_namebuf[MAXNAMELEN];
+
+	/*
+	 * All path steps observed during this scan.  Each of the path
+	 * steps for a particular pathwalk are recorded in sequential
+	 * order in the xfarray.  A pathwalk ends either with a step
+	 * pointing to the root directory (success) or pointing to NULLFSINO
+	 * (loop detected, empty dir detected, etc).
+	 */
+	struct xfarray		*path_steps;
+
+	/* All names observed during this scan. */
+	struct xfblob		*path_names;
+
+	/* All paths being tracked by this scanner. */
+	struct list_head	path_list;
+
+	/* Number of paths in path_list. */
+	unsigned int		nr_paths;
+
+	/* Number of parents found by a pptr scan. */
+	unsigned int		parents_found;
+
+	/* Have the path data been invalidated by a concurrent update? */
+	bool			stale:1;
+
+	/* Has the scan been aborted? */
+	bool			aborted:1;
+};
+
+#define xchk_dirtree_for_each_path_safe(dl, path, n) \
+	list_for_each_entry_safe((path), (n), &(dl)->path_list, list)
+
+#define xchk_dirtree_for_each_path(dl, path) \
+	list_for_each_entry((path), &(dl)->path_list, list)
+
+static inline bool
+xchk_dirtree_parentless(const struct xchk_dirtree *dl)
+{
+	struct xfs_scrub	*sc = dl->sc;
+
+	if (sc->ip == sc->mp->m_rootip)
+		return true;
+	if (VFS_I(sc->ip)->i_nlink == 0)
+		return true;
+	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/health.c

@@ -108,6 +108,7 @@ static const struct xchk_health_map type_to_health_flag[XFS_SCRUB_TYPE_NR] = {
 	[XFS_SCRUB_TYPE_FSCOUNTERS]	= { XHG_FS,  XFS_SICK_FS_COUNTERS },
 	[XFS_SCRUB_TYPE_QUOTACHECK]	= { XHG_FS,  XFS_SICK_FS_QUOTACHECK },
 	[XFS_SCRUB_TYPE_NLINKS]		= { XHG_FS,  XFS_SICK_FS_NLINKS },
+	[XFS_SCRUB_TYPE_DIRTREE]	= { XHG_INO, XFS_SICK_INO_DIRTREE },
 };
 
 /* Return the health status mask for this scrub type. */

fs/xfs/scrub/ino_bitmap.h

+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (c) 2023-2024 Oracle.  All Rights Reserved.
+ * Author: Darrick J. Wong <djwong@kernel.org>
+ */
+#ifndef __XFS_SCRUB_INO_BITMAP_H__
+#define __XFS_SCRUB_INO_BITMAP_H__
+
+/* Bitmaps, but for type-checked for xfs_ino_t */
+
+struct xino_bitmap {
+	struct xbitmap64	inobitmap;
+};
+
+static inline void xino_bitmap_init(struct xino_bitmap *bitmap)
+{
+	xbitmap64_init(&bitmap->inobitmap);
+}
+
+static inline void xino_bitmap_destroy(struct xino_bitmap *bitmap)
+{
+	xbitmap64_destroy(&bitmap->inobitmap);
+}
+
+static inline int xino_bitmap_set(struct xino_bitmap *bitmap, xfs_ino_t ino)
+{
+	return xbitmap64_set(&bitmap->inobitmap, ino, 1);
+}
+
+static inline int xino_bitmap_test(struct xino_bitmap *bitmap, xfs_ino_t ino)
+{
+	uint64_t	len = 1;
+
+	return xbitmap64_test(&bitmap->inobitmap, ino, &len);
+}
+
+#endif	/* __XFS_SCRUB_INO_BITMAP_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

@@ -436,6 +436,13 @@ static const struct xchk_meta_ops meta_scrub_ops[] = {
 		.scrub	= xchk_health_record,
 		.repair = xrep_notsupported,
 	},
+	[XFS_SCRUB_TYPE_DIRTREE] = {	/* directory tree structure */
+		.type	= ST_INODE,
+		.setup	= xchk_setup_dirtree,
+		.scrub	= xchk_dirtree,
+		.has	= xfs_has_parent,
+		.repair	= xrep_dirtree,
+	},
 };
 
 static int

fs/xfs/scrub/scrub.h

@@ -185,6 +185,7 @@ int xchk_directory(struct xfs_scrub *sc);
 int xchk_xattr(struct xfs_scrub *sc);
 int xchk_symlink(struct xfs_scrub *sc);
 int xchk_parent(struct xfs_scrub *sc);
+int xchk_dirtree(struct xfs_scrub *sc);
 #ifdef CONFIG_XFS_RT
 int xchk_rtbitmap(struct xfs_scrub *sc);
 int xchk_rtsummary(struct xfs_scrub *sc);

fs/xfs/scrub/stats.c

@@ -79,6 +79,7 @@ static const char *name_map[XFS_SCRUB_TYPE_NR] = {
 	[XFS_SCRUB_TYPE_FSCOUNTERS]	= "fscounters",
 	[XFS_SCRUB_TYPE_QUOTACHECK]	= "quotacheck",
 	[XFS_SCRUB_TYPE_NLINKS]		= "nlinks",
+	[XFS_SCRUB_TYPE_DIRTREE]	= "dirtree",
 };
 
 /* Format the scrub stats into a text buffer, similar to pcp style. */

fs/xfs/scrub/trace.c

@@ -28,6 +28,10 @@
 #include "scrub/orphanage.h"
 #include "scrub/nlinks.h"
 #include "scrub/fscounters.h"
+#include "scrub/bitmap.h"
+#include "scrub/ino_bitmap.h"
+#include "scrub/xfblob.h"
+#include "scrub/dirtree.h"
 
 /* Figure out which block the btree cursor was pointing to. */
 static inline xfs_fsblock_t

fs/xfs/scrub/xfarray.h

@@ -8,6 +8,7 @@
 
 /* xfile array index type, along with cursor initialization */
 typedef uint64_t		xfarray_idx_t;
+#define XFARRAY_NULLIDX		((__force xfarray_idx_t)-1ULL)
 #define XFARRAY_CURSOR_INIT	((__force xfarray_idx_t)0)
 
 /* Iterate each index of an xfile array. */

fs/xfs/xfs_health.c

@@ -470,6 +470,7 @@ static const struct ioctl_sick_map ino_map[] = {
 	{ XFS_SICK_INO_BMBTA_ZAPPED,	XFS_BS_SICK_BMBTA },
 	{ XFS_SICK_INO_DIR_ZAPPED,	XFS_BS_SICK_DIR },
 	{ XFS_SICK_INO_SYMLINK_ZAPPED,	XFS_BS_SICK_SYMLINK },
+	{ XFS_SICK_INO_DIRTREE,	XFS_BS_SICK_DIRTREE },
 	{ 0, 0 },
 };
 

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);