[PATCH 22/58] xfs: check metadata directory file path connectivity

["Darrick J. Wong" <djwong@kernel.org>]

From: Darrick J. Wong <djwong@kernel.org>

Create a new scrubber type that checks that well known metadata
directory paths are connected to the metadata inode that the incore
structures think is in use.  IOWs, check that "/quota/user" in the
metadata directory tree actually points to
mp->m_quotainfo->qi_uquotaip->i_ino.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
---
 libxfs/xfs_fs.h                     |   17 +++++++++++++++-
 libxfs/xfs_health.h                 |    4 +++-
 man/man2/ioctl_xfs_scrub_metadata.2 |   38 +++++++++++++++++++++++++++++++++++
 3 files changed, 57 insertions(+), 2 deletions(-)


diff --git a/libxfs/xfs_fs.h b/libxfs/xfs_fs.h
index 952e4fc93c4..a0efcbde5ae 100644
--- a/libxfs/xfs_fs.h
+++ b/libxfs/xfs_fs.h
@@ -198,6 +198,7 @@ struct xfs_fsop_geom {
 #define XFS_FSOP_GEOM_SICK_QUOTACHECK	(1 << 6)  /* quota counts */
 #define XFS_FSOP_GEOM_SICK_NLINKS	(1 << 7)  /* inode link counts */
 #define XFS_FSOP_GEOM_SICK_METADIR	(1 << 8)  /* metadata directory */
+#define XFS_FSOP_GEOM_SICK_METAPATH	(1 << 9)  /* metadir tree path */
 
 /* Output for XFS_FS_COUNTS */
 typedef struct xfs_fsop_counts {
@@ -731,9 +732,10 @@ struct xfs_scrub_metadata {
 #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 */
+#define XFS_SCRUB_TYPE_METAPATH	29	/* metadata directory tree paths */
 
 /* Number of scrub subcommands. */
-#define XFS_SCRUB_TYPE_NR	29
+#define XFS_SCRUB_TYPE_NR	30
 
 /*
  * This special type code only applies to the vectored scrub implementation.
@@ -788,6 +790,19 @@ struct xfs_scrub_metadata {
 				 XFS_SCRUB_OFLAG_NO_REPAIR_NEEDED)
 #define XFS_SCRUB_FLAGS_ALL	(XFS_SCRUB_FLAGS_IN | XFS_SCRUB_FLAGS_OUT)
 
+/*
+ * i: sm_ino values for XFS_SCRUB_TYPE_METAPATH to select a metadata file for
+ * path checking.
+ */
+#define XFS_SCRUB_METAPATH_RTBITMAP	0
+#define XFS_SCRUB_METAPATH_RTSUMMARY	1
+#define XFS_SCRUB_METAPATH_USRQUOTA	2
+#define XFS_SCRUB_METAPATH_GRPQUOTA	3
+#define XFS_SCRUB_METAPATH_PRJQUOTA	4
+
+/* Number of metapath sm_ino values */
+#define XFS_SCRUB_METAPATH_NR		5
+
 /*
  * ioctl limits
  */
diff --git a/libxfs/xfs_health.h b/libxfs/xfs_health.h
index d9b9968607f..1816c67351a 100644
--- a/libxfs/xfs_health.h
+++ b/libxfs/xfs_health.h
@@ -61,6 +61,7 @@ struct xfs_da_args;
 #define XFS_SICK_FS_QUOTACHECK	(1 << 4)  /* quota counts */
 #define XFS_SICK_FS_NLINKS	(1 << 5)  /* inode link counts */
 #define XFS_SICK_FS_METADIR	(1 << 6)  /* metadata directory tree */
+#define XFS_SICK_FS_METAPATH	(1 << 7)  /* metadata directory tree path */
 
 /* Observable health issues for realtime volume metadata. */
 #define XFS_SICK_RT_BITMAP	(1 << 0)  /* realtime bitmap */
@@ -105,7 +106,8 @@ struct xfs_da_args;
 				 XFS_SICK_FS_PQUOTA | \
 				 XFS_SICK_FS_QUOTACHECK | \
 				 XFS_SICK_FS_NLINKS | \
-				 XFS_SICK_FS_METADIR)
+				 XFS_SICK_FS_METADIR | \
+				 XFS_SICK_FS_METAPATH)
 
 #define XFS_SICK_RT_PRIMARY	(XFS_SICK_RT_BITMAP | \
 				 XFS_SICK_RT_SUMMARY)
diff --git a/man/man2/ioctl_xfs_scrub_metadata.2 b/man/man2/ioctl_xfs_scrub_metadata.2
index 44aa139b297..b1db740560d 100644
--- a/man/man2/ioctl_xfs_scrub_metadata.2
+++ b/man/man2/ioctl_xfs_scrub_metadata.2
@@ -200,6 +200,44 @@ Scan all inodes in the filesystem to verify each file's link count.
 Mark everything healthy after a clean scrub run.
 This clears out all the indirect health problem markers that might remain
 in the system.
+
+.TP
+.B XFS_SCRUB_TYPE_METAPATH
+Check that a metadata directory path actually points to the active metadata
+inode.
+Metadata inodes are usually cached for the duration of the mount, so this
+scrubber ensures that the same inode will still be reachable after an unmount
+and mount cycle.
+Discrepancies can happen if the directory or parent pointer scrubbers rebuild
+a metadata directory but lose a link in the process.
+The
+.B sm_ino
+field should be passed one of the following special values to communicate which
+path to check:
+
+.RS 7
+.TP
+.B XFS_SCRUB_METAPATH_RTBITMAP
+Realtime bitmap file.
+.TP
+.B XFS_SCRUB_METAPATH_RTSUMMARY
+Realtime summary file.
+.TP
+.B XFS_SCRUB_METAPATH_USRQUOTA
+User quota file.
+.TP
+.B XFS_SCRUB_METAPATH_GRPQUOTA
+Group quota file.
+.TP
+.B XFS_SCRUB_METAPATH_PRJQUOTA
+Project quota file.
+.RE
+
+The values of
+.I sm_agno
+and
+.I sm_gen
+must be zero.
 .RE
 
 .PD 1