[09/10] common/xfs: only pass -l in _xfs_mdrestore for v2 metadumps

Commit Message

Darrick J. Wong Jan. 25, 2024, 7:06 p.m. UTC

From: Darrick J. Wong <[e-mail]>

fstests has a weird history with external log devices -- prior to the
introduction of metadump v2, a dump/restore cycle would leave an
external log unaltered, and most tests worked just fine.  Were those
tests ignorant?  Or did they pass intentionally?

Either way, we don't want to pass -l to xfs_mdrestore just because we
have an external log, because that switch is new and causes regressions
when testing with xfsprogs from before 6.5.

Signed-off-by: Darrick J. Wong <[e-mail]>
---
 common/xfs |   25 ++++++++++++++++++++++++-
 1 file changed, 24 insertions(+), 1 deletion(-)

Comments

Christoph Hellwig Jan. 26, 2024, 1:36 p.m. UTC | #1

Looks good:

Reviewed-by: Christoph Hellwig <[e-mail]>

Patch

diff --git a/common/xfs b/common/xfs
index 6a48960a7f..65b509691b 100644
--- a/common/xfs
+++ b/common/xfs
@@ -689,12 +689,25 @@  _xfs_metadump() {
 	return $res
 }
 
+# What is the version of this metadump file?
+_xfs_metadumpfile_version() {
+	local file="$1"
+	local magic
+
+	magic="$($XFS_IO_PROG -c 'pread -q -v 0 4' "$file")"
+	case "$magic" in
+	"00000000:  58 4d 44 32  XMD2") echo 2;;
+	"00000000:  58 46 53 4d  XFSM") echo 1;;
+	esac
+}
+
 _xfs_mdrestore() {
 	local metadump="$1"
 	local device="$2"
 	local logdev="$3"
 	shift; shift; shift
 	local options="$@"
+	local dumpfile_ver
 
 	# If we're configured for compressed dumps and there isn't already an
 	# uncompressed dump, see if we can use DUMP_COMPRESSOR to decompress
@@ -705,8 +718,18 @@  _xfs_mdrestore() {
 		done
 	fi
 	test -r "$metadump" || return 1
+	dumpfile_ver="$(_xfs_metadumpfile_version "$metadump")"
 
-	if [ "$logdev" != "none" ]; then
+	if [ "$logdev" != "none" ] && [[ $dumpfile_ver > 1 ]]; then
+		# metadump and mdrestore began capturing and restoring the
+		# contents of external log devices with the addition of the
+		# metadump v2 format.  Hence it only makes sense to specify -l
+		# here if the dump file itself is in v2 format.
+		#
+		# With a v1 metadump, the log device is not changed by the dump
+		# and restore process.  Historically, fstests either didn't
+		# notice or _notrun themselves when external logs were in use.
+		# Don't break that for people testing with xfsprogs < 6.5.
 		options="$options -l $logdev"
 	fi