Bug#995104: d-i: partman-basicfilesystems; swap
Package: partman-basicfilesystems
Version: 156
Tags: patch
Hello d-i team,
I am not happy with current swap management in manual partitioning.
1) All existing swaps are automatically marked as used and formatted.
Formatting an existing swap changes its UUID. On multiboot setups this
breaks other installed systems such as Debian which use these swaps and
rely on UUID to identify them. I have read multiple reports on Debian
user forums from people which did not notice that all swaps were marked
as used and to be formatted and broke already installed systems.
On the other hand, I cannot see any benefit in formatting an existing
swap. The transition from old swap format v0 to current format v1 was 20
years ago, so I doubt that any v0 swap still exists on any disk in use.
Is it to avoid on-disk format incompatibilities between architectures
(endianness, page size...) ?
Also, activating a shared swap removes the hibernation image that may
have been written by another system. This breaks suspending a system to
disk and rebooting another system.
For these reasons I propose to disable this feature. I think it is
better that people who use manual partitioning select swaps they want to
use instead of deselecting swaps they do not want to use.
2) Partman forces used existing swaps to be formated.
As explained above, formatting an existing swap is useless and may break
other installed systems which use it.
3) Partman does not allow the user to choose to format or not format an
existing swap.
Actually most of the needed code is present but can never be reached due
to improper checks.
The attached patch makes the following changes:
- disable automatic use and format of existing swaps
init.d/autouse_swap
- do not format existing swap by default when manually selected
choose_method/swap/do_option
- enable choice to format or not format an existing swap
active_partition/basicfilesystems/choices
active_partition/basicfilesystems/do_option
Caveat: I don't know how this is compatible with non-Linux architectures
which may use different swap formats.
diff -ur a/active_partition/basicfilesystems/choices b/active_partition/basicfilesystems/choices
--- a/active_partition/basicfilesystems/choices 2021-07-23 19:14:05.000000000 +0200
+++ b/active_partition/basicfilesystems/choices 2021-09-26 01:08:03.102852685 +0200
@@ -10,19 +10,24 @@
cd $dev
-[ -f $part/method -a -f $part/acting_filesystem ] || exit 0
+[ -f $part/method ] || exit 0
method=$(cat $part/method)
-filesystem=$(cat $part/acting_filesystem)
-case "$filesystem" in
- ext2|fat16|fat32|ntfs)
+if [ "$method" = swap ]; then
:
- ;;
- *)
+elif [ -f $part/acting_filesystem ]; then
+ filesystem=$(cat $part/acting_filesystem)
+ case "$filesystem" in
+ ext2|fat16|fat32|ntfs)
+ ;;
+ *)
+ exit 0
+ ;;
+ esac
+else
exit 0
- ;;
-esac
+fi
choice_mountpoint () {
case "$filesystem" in
@@ -40,6 +45,7 @@
}
choice_options () {
+ [ "$filesystem" ] || return 0
db_metaget partman-basicfilesystems/text/options description
printf "options\t%s\${!TAB}%.45s\n" "$RET" "$(get_mountoptions $dev $id)"
}
@@ -51,11 +57,10 @@
description="$RET"
if [ -f $part/format ]; then
db_metaget partman-basicfilesystems/text/yes description
- printf "dont_format_swap\t%s\${!TAB}%s\n" "$description" "${RET}"
else
db_metaget partman-basicfilesystems/text/no description
- printf "format_swap\t%s\${!TAB}%s\n" "$description" "${RET}"
fi
+ printf "format_swap\t%s\${!TAB}%s\n" "$description" "${RET}"
fi
}
diff -ur a/active_partition/basicfilesystems/do_option b/active_partition/basicfilesystems/do_option
--- a/active_partition/basicfilesystems/do_option 2021-07-23 19:14:05.000000000 +0200
+++ b/active_partition/basicfilesystems/do_option 2021-09-26 01:08:15.655006505 +0200
@@ -8,8 +8,11 @@
cd $dev
-[ -f $part/method -a -f $part/acting_filesystem ] || exit 0
-filesystem=$(cat $part/acting_filesystem)
+[ -f $part/method ] || exit 0
+if [ "$(cat $part/method)" != swap ]; then
+ [ -f $part/acting_filesystem ] || exit 0
+ filesystem=$(cat $part/acting_filesystem)
+fi
do_fatmountpoint () {
local noninteractive tpl
@@ -94,14 +97,12 @@
select_mountoptions $dev $id
;;
format_swap)
- >$part/format
- update_partition $dev $id
- ;;
- dont_format_swap)
if [ -f $part/format ]; then
rm $part/format
- update_partition $dev $id
+ else
+ >$part/format
fi
+ update_partition $dev $id
;;
label)
label=''
diff -ur a/choose_method/swap/do_option b/choose_method/swap/do_option
--- a/choose_method/swap/do_option 2021-07-23 19:14:05.000000000 +0200
+++ b/choose_method/swap/do_option 2021-09-26 01:09:39.976109430 +0200
@@ -11,6 +11,17 @@
old_method=do_not_use
fi
+# keep settings if already selected as swap
+[ "$old_method" = swap ] && exit 0
+
echo swap >$dev/$id/method
->$dev/$id/format
+
+# format only if does not already contain swap
+if [ -f $dev/$id/detected_filesystem ] &&
+ [ "$(cat $dev/$id/detected_filesystem)" = linux-swap ]; then
+ rm -f $dev/$id/format
+else
+ >$dev/$id/format
+fi
+
rm -f $dev/$id/use_filesystem
diff -ur a/init.d/autouse_swap b/init.d/autouse_swap
--- a/init.d/autouse_swap 2021-07-23 19:14:05.000000000 +0200
+++ b/init.d/autouse_swap 2021-09-26 01:10:29.608810228 +0200
@@ -2,6 +2,9 @@
. /lib/partman/lib/base.sh
+# disable automatic use of existing swap
+exit 0
+
mkdir -p /var/lib/partman/autoused_swap
partitions=
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