From d460ac1ed1a4fd1d66d90d5793f776ca7c5969db Mon Sep 17 00:00:00 2001
From: "Darrick J. Wong" <djwong@kernel.org>
Date: Wed, 7 Aug 2024 15:54:57 -0700
Subject: [PATCH] xfs_scrubbed: check for fs features needed for effective
 repairs

Online repair relies heavily on back references such as reverse mappings
and directory parent pointers to add redundancy to the filesystem.
Check for these two features and whine a bit if they are missing.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
---
 scrub/xfs_scrubbed.in | 72 +++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 72 insertions(+)

diff --git a/scrub/xfs_scrubbed.in b/scrub/xfs_scrubbed.in
index 1391b565d..e70da45a6 100644
--- a/scrub/xfs_scrubbed.in
+++ b/scrub/xfs_scrubbed.in
@@ -69,6 +69,8 @@ log = False
 everything = False
 printf_prefix = ''
 want_repair = False
+has_parent = False
+has_rmapbt = False
 libhandle = None
 repair_queue = None # placeholder for event queue worker
 
@@ -341,6 +343,57 @@ def xfs_repair_inode_metadata(fd, type, ino, gen):
 	'''Call the kernel to repair some inode metadata.'''
 	return __xfs_repair_metadata(fd, type, 0, ino, gen)
 
+# fsgeometry ioctl
+class xfs_fsop_geom(ctypes.Structure):
+	_fields_ = [
+		("blocksize",		ctypes.c_uint),
+		("rtextesize",		ctypes.c_uint),
+		("agblocks",		ctypes.c_uint),
+		("agcount",		ctypes.c_uint),
+		("logblocks",		ctypes.c_uint),
+		("sectsize",		ctypes.c_uint),
+		("inodesize",		ctypes.c_uint),
+		("imaxpct",		ctypes.c_uint),
+		("datablocks",		ctypes.c_ulonglong),
+		("rtblocks",		ctypes.c_ulonglong),
+		("rtextents",		ctypes.c_ulonglong),
+		("logstart",		ctypes.c_ulonglong),
+		("uuid",		ctypes.c_ubyte * 16),
+		("sunit",		ctypes.c_uint),
+		("swidth",		ctypes.c_uint),
+		("version",		ctypes.c_uint),
+		("flags",		ctypes.c_uint),
+		("logsectsize",		ctypes.c_uint),
+		("rtsectsize",		ctypes.c_uint),
+		("dirblocksize",	ctypes.c_uint),
+		("logsunit",		ctypes.c_uint),
+		("sick",		ctypes.c_uint),
+		("checked",		ctypes.c_uint),
+		("rgblocks",		ctypes.c_uint),
+		("rgcount",		ctypes.c_uint),
+		("_pad",		ctypes.c_ulonglong * 16),
+	]
+assert ctypes.sizeof(xfs_fsop_geom) == 256
+
+XFS_FSOP_GEOM_FLAGS_RMAPBT	= 1 << 19
+XFS_FSOP_GEOM_FLAGS_PARENT	= 1 << 25
+
+XFS_IOC_FSGEOMETRY		= _IOR (0x58, 126, xfs_fsop_geom)
+
+def xfs_has_parent(fd):
+	'''Does this filesystem have parent pointers?'''
+
+	arg = xfs_fsop_geom()
+	fcntl.ioctl(fd, XFS_IOC_FSGEOMETRY, arg)
+	return arg.flags & XFS_FSOP_GEOM_FLAGS_PARENT != 0
+
+def xfs_has_rmapbt(fd):
+	'''Does this filesystem have reverse mapping?'''
+
+	arg = xfs_fsop_geom()
+	fcntl.ioctl(fd, XFS_IOC_FSGEOMETRY, arg)
+	return arg.flags & XFS_FSOP_GEOM_FLAGS_RMAPBT != 0
+
 # main program
 
 def health_reports(mon_fp, fh):
@@ -458,9 +511,28 @@ def monitor(mountpoint, event_queue, **kwargs):
 	global log
 	global printf_prefix
 	global want_repair
+	global has_parent
+	global has_rmapbt
 
 	fh = None
 	fd = os.open(mountpoint, os.O_RDONLY)
+	try:
+		has_parent = xfs_has_parent(fd)
+		has_rmapbt = xfs_has_rmapbt(fd)
+	except Exception as e:
+		# Don't care if we can't detect parent pointers or rmap
+		print(e, file = sys.stderr)
+
+	# Check for the backref metadata that makes repair effective.
+	if want_repair:
+		if not has_rmapbt:
+			print(f"{mountpoint}: XFS online repair is less effective without rmap btrees.")
+		if not has_parent:
+			print(f"{mountpoint}: XFS online repair is less effective without parent pointers.")
+
+	# Flush anything that we may have printed about operational state.
+	sys.stdout.flush()
+
 	try:
 		if want_repair:
 			fh = fshandle(fd, mountpoint)
-- 
2.50.1