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 <[email protected]>
Signed-off-by: Chandan Babu R <[email protected]>

* 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

Author: Chandan Babu R

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);