#!/bin/bash
# set -x
set -e

# lfs_migrate: a simple tool to copy and check files.
#
# To avoid allocating objects on one or more OSTs, they should be
# deactivated on the MDS via "lctl --device {device_number} deactivate",
# where {device_number} is from the output of "lctl dl" on the MDS.
#
# To guard against corruption, the file is compared after migration
# to verify the copy is correct and the file has not been modified.
# This is not a protection against the file being open by another
# process, but it would catch the worst cases of in-use files, but
# to be 100% safe the administrator needs to ensure this is safe.

RSYNC=${RSYNC:-rsync}
ECHO=echo
LFS=${LFS:-lfs}

usage() {
    cat -- <<USAGE 1>&2
usage: lfs_migrate [-c|-s] [-h] [-l] [-n] [-y] [file|dir ...]
    -c compare file data after migrate (default)
    -s skip file data comparison after migrate
    -h show this usage message
    -l migrate files with hard links (skip by default)
    -n only print the names of files to be migrated
    -q run quietly (don't print filenames or status)
    -y answer 'y' to usage question

If a directory is an argument, all files in the directory are migrated.
If no file/directory is given, the file list is read from standard input.

e.g.: lfs_migrate /mnt/lustre/file
      lfs find /test -O test-OST0004 -size +4G | lfs_migrate -y
USAGE
    exit 1
}

OPT_CHECK=y

while getopts "chlnqsy" opt $*; do
    case $opt in
	c) OPT_CHECK=y;;
	l) OPT_NLINK=y;;
	n) OPT_DRYRUN=n; OPT_YES=y;;
	q) ECHO=:;;
	s) OPT_CHECK="";;
	y) OPT_YES=y;;
	h|\?) usage;;
    esac
done
shift $((OPTIND - 1))

if [ -z "$OPT_YES" ]; then
	echo ""
	echo "lfs_migrate is currently NOT SAFE for moving in-use files." 1>&2
	echo "Use it only when you are sure migrated files are unused." 1>&2
	echo "" 1>&2
	echo "If emptying OST(s) that are not disabled on the MDS, new" 1>&2
	echo "files may use them.  To prevent MDS allocating any files on" 1>&2
	echo "OSTNNNN run 'lctl --device %{fsname}-OSTNNNN-osc deactivate'" 1>&2
	echo "on the MDS." 1>&2
	echo -n "Continue? (y/n) "
	read CHECK
	[ "$CHECK" != "y" -a "$CHECK" != "yes" ] && exit 1
fi

# if rsync has --xattr support, then try to copy the xattrs.
$RSYNC --help 2>&1 | grep -q xattr && RSYNC_OPTS="$RSYNC_OPTS -X"
$RSYNC --help 2>&1 | grep -q acls && RSYNC_OPTS="$RSYNC_OPTS -A"
# If rsync copies lustre xattrs in the future, then we can skip lfs (bug 22189)
strings $(which $RSYNC) 2>&1 | grep -q lustre && LFS=:

lfs_migrate() {
	while read OLDNAME; do
		$ECHO -n "$OLDNAME: "

		# avoid duplicate stat if possible
		TYPE_LINK=($(stat -c "%h %F" "$OLDNAME" || true))

		# skip non-regular files, since they don't have any objects
		# and there is no point in trying to migrate them.
		if [ "${TYPE_LINK[1]}" != "regular" ]; then
			echo -e "not a regular file, skipped"
			continue
		fi

		if [ -z "$OPT_NLINK" -a ${TYPE_LINK[0]} -gt 1 ]; then
			echo -e "multiple hard links, skipped"
			continue
		fi

		# working out write perms is hard, let the shell do it
		if [ ! -w "$OLDNAME" ]; then
			echo -e "no write permission, skipped"
			continue
		fi

		if [ "$OPT_DRYRUN" ]; then
			echo -e "dry run, skipped"
			continue
		fi


		# if rsync copies Lustre xattrs properly in the future
		# (i.e. before the file data, so that it preserves striping)
		# then we don't need to do this getstripe/mktemp stuff.
		UNLINK="-u"
		COUNT=$($LFS getstripe -c "$OLDNAME" 2> /dev/null)
		SIZE=$($LFS getstripe -s "$OLDNAME" 2> /dev/null)
		[ -z "$COUNT" -o -z "$SIZE" ] && UNLINK=""
		NEWNAME=$(mktemp $UNLINK "$OLDNAME.tmp.XXXXXX")
		if [ $? -ne 0 -o -z "$NEWNAME" ]; then
			echo -e "\r$OLDNAME: can't make temp file, skipped" 1>&2
			continue
		fi

		[ "$UNLINK" ] && $LFS setstripe -c${COUNT} -s${SIZE} "$NEWNAME"

		# we use --inplace, since we created our own temp file already
		if ! $RSYNC -a --inplace $RSYNC_OPTS "$OLDNAME" "$NEWNAME";then
			echo -e "\r$OLDNAME: copy error, exiting" 1>&2
			rm -f "$NEWNAME"
			exit 4
		fi

		if [ "$OPT_CHECK" ] && ! cmp "$OLDNAME" "$NEWNAME"; then
			echo -e "\r$NEWNAME: compare failed, exiting" 1>&2
			exit 8
		fi

		if ! mv "$NEWNAME" "$OLDNAME"; then
			echo -e "\r$OLDNAME: rename error, exiting" 1>&2
			exit 12
		fi
		$ECHO "done"
	done
}

if [ "$#" -eq 0 ]; then
	lfs_migrate
else
	while [ "$1" ]; do
		if [ -d "$1" ]; then
			lfs find "$1" -type f | lfs_migrate
		else
			echo $1 | lfs_migrate
		fi
		shift
	done
fi