common/xfs: only pass -l in _xfs_mdrestore for v2 metadumps

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" <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Zorro Lang <zlang@kernel.org>

diff --git a/common/xfs b/common/xfs
index 6a48960a7ff2c0890b845f3e56f3c1bd3abe2137..65b509691b66edae98b8d24f4274cd04dc00edd0 100644 (file)
--- 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 "$metadump" || return 1
-
-       if [ "$logdev" != "none" ]; then
+       dumpfile_ver="$(_xfs_metadumpfile_version "$metadump")"
+
+       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