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[2/6] xfs: teach online scrub to find directory tree structure problems

Message ID 170405007459.1805996.13319683096140892679.stgit@frogsfrogsfrogs (mailing list archive)
State Superseded
Headers show
Series [1/6] xfs_db: add link and unlink expert commands | expand

Commit Message

Darrick J. Wong Dec. 31, 2023, 11:18 p.m. UTC 
From: Darrick J. Wong <djwong@kernel.org>

Create a new scrubber that detects corruptions within the directory tree
structure itself.  It can detect directories with multiple parents;
loops within the directory tree; and directory loops not accessible from
the root.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
---
 libfrog/scrub.c                     |    5 +++++
 libxfs/xfs_fs.h                     |    3 ++-
 man/man2/ioctl_xfs_scrub_metadata.2 |   14 ++++++++++++++
 3 files changed, 21 insertions(+), 1 deletion(-)
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Patch

diff --git a/libfrog/scrub.c b/libfrog/scrub.c
index baaa4b4d940..a2146e228f5 100644
--- a/libfrog/scrub.c
+++ b/libfrog/scrub.c
@@ -149,6 +149,11 @@  const struct xfrog_scrub_descr xfrog_scrubbers[XFS_SCRUB_TYPE_NR] = {
 		.descr	= "retained health records",
 		.group	= XFROG_SCRUB_GROUP_NONE,
 	},
+	[XFS_SCRUB_TYPE_DIRTREE] = {
+		.name	= "dirtree",
+		.descr	= "directory tree structure",
+		.group	= XFROG_SCRUB_GROUP_INODE,
+	},
 };
 #undef DEP
 
diff --git a/libxfs/xfs_fs.h b/libxfs/xfs_fs.h
index efa68a2d82a..48f38694f12 100644
--- a/libxfs/xfs_fs.h
+++ b/libxfs/xfs_fs.h
@@ -719,9 +719,10 @@  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)
diff --git a/man/man2/ioctl_xfs_scrub_metadata.2 b/man/man2/ioctl_xfs_scrub_metadata.2
index 75ae52bb584..44aa139b297 100644
--- a/man/man2/ioctl_xfs_scrub_metadata.2
+++ b/man/man2/ioctl_xfs_scrub_metadata.2
@@ -148,6 +148,20 @@  that points back to the subdirectory.
 The inode to examine can be specified in the same manner as
 .BR XFS_SCRUB_TYPE_INODE "."
 
+.TP
+.B XFS_SCRUB_TYPE_DIRTREE
+This scrubber looks for problems in the directory tree structure such as loops
+and directories accessible through more than one path.
+Problems are detected by walking parent pointers upwards towards the root.
+Loops are detected by comparing the parent directory at each step against the
+directories already examined.
+Directories with multiple paths are detected by counting the parent pointers
+attached to a directory.
+Non-directories do not have links pointing away from the directory tree root
+and can be skipped.
+The directory to examine can be specified in the same manner as
+.BR XFS_SCRUB_TYPE_INODE "."
+
 .TP
 .B XFS_SCRUB_TYPE_SYMLINK
 Examine the target of a symbolic link for obvious pathname problems.