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homework: skip LUKS fallocate for metadata operations

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UpdateHomeEx needs to set up the home temporarily so that it can
write the refreshed identity records. Inspect and password changes use
the same setup path for metadata-oriented work.

For LUKS homes with luksDiscard=no, home_setup_luks() fully
allocates the backing image while setting it up. If diskSize=max was
previously written to a sparse image, this can fail with ENOSPC before
the user can disable auto-resize mode again.

Add a setup flag that lets metadata operations skip the full-image
fallocate step. Real create, activate, and resize paths keep the
existing allocation behavior.

Before, reproduced on Ubuntu 26.04 with /home on tmpfs:

  homectl create reprohomed \
          --storage=luks \
          --fs-type=btrfs \
          --disk-size=300M \
          --auto-resize-mode=shrink-and-grow \
          --luks-discard=no
  homectl update reprohomed --disk-size=max
  dd if=/dev/zero of=/var/tmp/homed-repro/filler bs=1M count=500
  systemctl restart systemd-homed.service
  homectl update reprohomed --auto-resize-mode=off

  Operation on home reprohomed failed:
  Not enough disk space for home reprohomed

Fixes #34527

Follow-up for: ab3b6fcb40
This commit is contained in:
dongshengyuan
2026-08-27 04:54:38 +09:00
committed by Yu Watanabe
parent a9ff124143
commit 2ff5250ae7
4 changed files with 132 additions and 7 deletions
Download Patch File Download Diff File Expand all files Collapse all files
src/home/homework-luks.c
+5 -3
View File
@@ -1430,7 +1430,7 @@ int home_setup_luks(
if (run_mark_dirty(setup->image_fd, true) > 0)
setup->do_mark_clean = true;
if (!user_record_luks_discard(h)) {
if (!FLAGS_SET(flags, HOME_SETUP_LUKS_DONT_FALLOCATE) && !user_record_luks_discard(h)) {
r = run_fallocate(setup->image_fd, &st);
if (r < 0)
return r;
@@ -1505,7 +1505,9 @@ int home_setup_luks(
if (user_record_luks_discard(h))
(void) run_fitrim(setup->root_fd);
setup->do_offline_fallocate = !(setup->do_offline_fitrim = user_record_luks_offline_discard(h));
setup->do_offline_fitrim = user_record_luks_offline_discard(h);
setup->do_offline_fallocate = !setup->do_offline_fitrim;
setup->tolerate_offline_fallocate_enospc = FLAGS_SET(flags, HOME_SETUP_LUKS_DONT_FALLOCATE);
}
if (!sd_id128_is_null(found_partition_uuid))
@@ -1609,7 +1611,7 @@ int home_activate_luks(
r = home_setup_luks(
h,
0,
flags,
NULL,
setup,
cache,
src/home/homework.c
+8 -4
View File
@@ -436,7 +436,10 @@ int home_setup_done(HomeSetup *setup) {
if (setup->image_fd >= 0) {
if (setup->do_offline_fallocate) {
q = run_fallocate(setup->image_fd, NULL);
if (q < 0)
if (setup->tolerate_offline_fallocate_enospc &&
ERRNO_IS_NEG_DISK_SPACE(q))
log_warning_errno(q, "Failed to allocate backing file, ignoring: %m");
else if (q < 0)
r = q;
}
@@ -468,6 +471,7 @@ int home_setup_done(HomeSetup *setup) {
setup->undo_dm = false;
setup->do_offline_fitrim = false;
setup->do_offline_fallocate = false;
setup->tolerate_offline_fallocate_enospc = false;
setup->do_mark_clean = false;
setup->dm_name = mfree(setup->dm_name);
@@ -1686,7 +1690,7 @@ static int home_update(UserRecord *h, Hashmap *blobs, UserRecord **ret) {
return user_record_clone(h, USER_RECORD_LOAD_MASK_SECRET|USER_RECORD_PERMISSIVE, ret);
}
r = home_setup(h, flags, &setup, &cache, &header_home);
r = home_setup(h, flags | HOME_SETUP_LUKS_DONT_FALLOCATE, &setup, &cache, &header_home);
if (r < 0)
return r;
@@ -1788,7 +1792,7 @@ static int home_passwd(UserRecord *h, UserRecord **ret_home) {
if (r < 0)
return r;
r = home_setup(h, flags, &setup, &cache, &header_home);
r = home_setup(h, flags | HOME_SETUP_LUKS_DONT_FALLOCATE, &setup, &cache, &header_home);
if (r < 0)
return r;
@@ -1866,7 +1870,7 @@ static int home_inspect(UserRecord *h, UserRecord **ret_home) {
if (r < 0)
return r;
r = home_setup(h, flags, &setup, &cache, &header_home);
r = home_setup(h, flags | HOME_SETUP_LUKS_DONT_FALLOCATE, &setup, &cache, &header_home);
if (r < 0)
return r;
src/home/homework.h
+4
View File
@@ -48,6 +48,7 @@ typedef struct HomeSetup {
bool undo_mount:1; /* Whether to unmount /run/systemd/user-home-mount */
bool do_offline_fitrim:1;
bool do_offline_fallocate:1;
bool tolerate_offline_fallocate_enospc:1;
bool do_mark_clean:1;
bool do_drop_caches:1;
@@ -82,6 +83,9 @@ typedef enum HomeSetupFlags {
HOME_SETUP_RESIZE_DONT_GROW = 1 << 4, /* If the resize would grow, gracefully terminate operation */
HOME_SETUP_RESIZE_DONT_SHRINK = 1 << 5, /* If the resize would shrink, gracefully terminate operation */
HOME_SETUP_RESIZE_DONT_UNDO = 1 << 6, /* Leave loopback/DM device context open after successful operation */
/* LUKS backend: */
HOME_SETUP_LUKS_DONT_FALLOCATE = 1 << 7, /* Skip setup-time backing file allocation */
} HomeSetupFlags;
int home_setup_done(HomeSetup *setup);
test/units/TEST-46-HOMED.sh
+115
View File
@@ -40,6 +40,22 @@ wait_for_state() {
timeout 2m bash -c "until homectl inspect '${1:?}' | grep -F 'State: $2' >/dev/null; do sleep 2; done"
}
cleanup_update_auto_resize_mode_without_space() (
set +e
rm -f /tmp/no-space-update.create /home/no-space-update.filler /home/no-space-update.home
if homectl inspect no-space-update >/dev/null 2>&1; then
homectl deactivate no-space-update 2>/dev/null
wait_for_state no-space-update inactive 2>/dev/null
homectl remove no-space-update 2>/dev/null
fi
mount /home -o remount,size=290M || :
systemctl restart systemd-homed.service || :
return 0
)
FSTYPE="$(stat --file-system --format "%T" /)"
systemctl start systemd-homed.service systemd-userdbd.socket
@@ -337,6 +353,105 @@ testcase_recovery_key_file() (
rm -rf "$KEY_DIR"
)
testcase_update_auto_resize_mode_without_space() {
local blocks bsize create_output fill_mbytes fill_size filler home_size image
local fs_stat image_stat image_blocks image_size image_unallocated
create_output="/tmp/no-space-update.create"
filler="/home/no-space-update.filler"
home_size=512M
image="/home/no-space-update.home"
trap cleanup_update_auto_resize_mode_without_space RETURN ERR EXIT
mount /home -o remount,size="$home_size"
if ! NEWPASSWORD=xEhErW0ndafV4s \
homectl create no-space-update \
--storage=luks \
--disk-size=300M \
--auto-resize-mode=shrink-and-grow \
--luks-discard=no \
--luks-offline-discard=yes \
--image-path="$image" \
--luks-pbkdf-type=pbkdf2 \
--luks-pbkdf-time-cost=1ms \
--rate-limit-interval=1s \
--rate-limit-burst=1000 \
>"$create_output" 2>&1; then
if grep -F "System does not support selected storage backend" "$create_output" >/dev/null; then
cat "$create_output"
echo "LUKS storage backend not supported, skipping update without space test."
return 0
fi
cat "$create_output" >&2
return 1
fi
cat "$create_output"
PASSWORD=xEhErW0ndafV4s homectl update no-space-update --disk-size=max
wait_for_state no-space-update inactive
# Activation still fully allocates luksDiscard=no images while space is available.
PASSWORD=xEhErW0ndafV4s homectl activate no-space-update
wait_for_state no-space-update active
homectl deactivate no-space-update
wait_for_state no-space-update inactive
PASSWORD=xEhErW0ndafV4s homectl resize no-space-update 256M
wait_for_state no-space-update inactive
PASSWORD=xEhErW0ndafV4s homectl update no-space-update --disk-size=max
wait_for_state no-space-update inactive
image_stat="$(stat -c '%s %b' "$image")"
read -r image_size image_blocks <<<"$image_stat"
[[ "$image_size" =~ ^[0-9]+$ && "$image_blocks" =~ ^[0-9]+$ ]]
image_unallocated=$((image_size - image_blocks * 512))
fs_stat="$(stat --file-system --format "%a %S" /home)"
read -r blocks bsize <<<"$fs_stat"
[[ "$blocks" =~ ^[0-9]+$ && "$bsize" =~ ^[0-9]+$ ]]
fill_size=$((blocks * bsize - 128 * 1024 * 1024))
fill_mbytes=$((fill_size / 1024 / 1024))
if [[ "$fill_mbytes" -le 0 ]]; then
echo "Not enough free space to set up update without space test, skipping."
return 0
fi
# Leave enough room for the small identity update below, but not enough for the old full-image fallocate().
dd if=/dev/zero of="$filler" bs=1M count="$fill_mbytes"
fs_stat="$(stat --file-system --format "%a %S" /home)"
read -r blocks bsize <<<"$fs_stat"
[[ "$blocks" =~ ^[0-9]+$ && "$bsize" =~ ^[0-9]+$ ]]
if [[ "$image_unallocated" -le $((blocks * bsize)) ]]; then
printf 'Not enough backing space for the update test: '
printf 'image_unallocated=%s free_space=%s fill_mbytes=%s\n' \
"$image_unallocated" "$((blocks * bsize))" "$fill_mbytes"
return 0
fi
systemctl restart systemd-homed.service
wait_for_exist no-space-update
PASSWORD=xEhErW0ndafV4s homectl authenticate no-space-update
PASSWORD=xEhErW0ndafV4s homectl update no-space-update \
--luks-discard=yes \
--luks-offline-discard=no
PASSWORD=xEhErW0ndafV4s homectl update no-space-update \
--luks-discard=no \
--luks-offline-discard=yes
PASSWORD=xEhErW0ndafV4s NEWPASSWORD=yPN4N0fYNKUkOq homectl passwd no-space-update
PASSWORD=yPN4N0fYNKUkOq homectl update no-space-update --auto-resize-mode=off
homectl inspect no-space-update | grep -F "Auto Resize: off" >/dev/null
}
testcase_blob() {
# blob directory tests
# See docs/USER_RECORD_BLOB_DIRS.md