common/defrag: rework _require_defrag for ext4

The existing _require_defrag function rejects ext4 file systems
mounted with the dax option or constructed without extents.
However, there are also a number of other ext4 file system
configuration cases that do not currently support online defrag,
including encryption, data journaling, and bigalloc.  In the future,
online defrag functionality may be implemented for some of these,
and new configuration cases could be added that don't support it.

Rather than add a laundry list of mount and file system
configuration options to the existing _require_defrag function that
will need ongoing maintenance, use the available src/e4compact
program to directly determine whether the kernel supports ext4's
move extent ioctl on the test file system.

Signed-off-by: Eric Whitney <enwlinux@gmail.com>
Reviewed-by: Eryu Guan <eguan@redhat.com>
Signed-off-by: Eryu Guan <eguan@redhat.com>

diff --git a/common/defrag b/common/defrag
index 7db0cb4d02d4c98447d96463f9a79c98d5865c70..986b4bf254f90f637fdac7f90b189d725fcaadb5 100644 (file)
--- a/common/defrag
+++ b/common/defrag
@@ -27,14 +27,19 @@ _require_defrag()
         DEFRAG_PROG="$XFS_FSR_PROG"
        ;;
     ext4|ext4dev)
-       echo $MOUNT_OPTIONS | grep -q dax
+       testfile="$TEST_DIR/$$-test.defrag"
+       donorfile="$TEST_DIR/$$-donor.defrag"
+       bsize=`get_block_size $TEST_DIR`
+       $XFS_IO_PROG -f -c "pwrite -b $bsize 0 $bsize" $testfile > /dev/null
+       cp $testfile $donorfile
+       echo $testfile | $here/src/e4compact -v -f $donorfile | \
+               grep -q "err:95"
        if [ $? -eq 0 ]; then
-               _notrun "$FSTYP defragmentation not supported with DAX"
-       else
-               DEFRAG_PROG="$E4DEFRAG_PROG"
+               rm -f $testfile $donorfile 2>&1 > /dev/null
+               _notrun "$FSTYP test filesystem doesn't support online defrag"
        fi
-       dumpe2fs -h $TEST_DEV 2> /dev/null | grep -wq extent || \
-               _notrun "file system does not have extents, needed for defrag"
+       rm -f $testfile $donorfile 2>&1 > /dev/null
+       DEFRAG_PROG="$E4DEFRAG_PROG"
        ;;
     btrfs)
        DEFRAG_PROG="$BTRFS_UTIL_PROG filesystem defragment"