lvcreate: --quiet doesn't suppress overallocation warning.

[dseomn]

Is there any way to suppress the warning below? I only want to see errors.

dseomn@ilus:~$ sudo lvcreate --quiet --quiet -s -n delete-me ilus-vg/data_test
  WARNING: Sum of all thin volume sizes (<2.01 TiB) exceeds the size of thin pool ilus-vg/thin_pool and the size of whole volume group (465.28 GiB).

In case it helps:

dseomn@ilus:~$ sudo lvcreate --version
  LVM version:     2.03.11(2) (2021-01-08)
  Library version: 1.02.175 (2021-01-08)
  Driver version:  4.43.0
  Configuration:   ./configure --build=x86_64-linux-gnu --prefix=/usr --includedir=${prefix}/include --mandir=${prefix}/share/man --infodir=${prefix}/share/info --sysconfdir=/etc --localstatedir=/var --disable-option-checking --disable-silent-rules --libdir=${prefix}/lib/x86_64-linux-gnu --runstatedir=/run --disable-maintainer-mode --disable-dependency-tracking --libdir=/lib/x86_64-linux-gnu --sbindir=/sbin --with-usrlibdir=/usr/lib/x86_64-linux-gnu --with-optimisation=-O2 --with-cache=internal --with-device-uid=0 --with-device-gid=6 --with-device-mode=0660 --with-default-pid-dir=/run --with-default-run-dir=/run/lvm --with-default-locking-dir=/run/lock/lvm --with-thin=internal --with-thin-check=/usr/sbin/thin_check --with-thin-dump=/usr/sbin/thin_dump --with-thin-repair=/usr/sbin/thin_repair --with-udev-prefix=/ --enable-applib --enable-blkid_wiping --enable-cmdlib --enable-dmeventd --enable-editline --enable-lvmlockd-dlm --enable-lvmlockd-sanlock --enable-lvmpolld --enable-notify-dbus --enable-pkgconfig --enable-udev_rules --enable-udev_sync --disable-readline

[utkonos]

My own use case is that I make a large number of snapshots which eventually trigger all of these warnings even though the actual used space is nowhere near the size that will endanger the pool. When I am done with a particular task, all the snapshots are deleted leaving the base volume. I don't need any of these warnings and I would like them all suppressed. I know of other projects and users who would like to suppress this warning as well along with the other three that you are suppressing via --quiet. Here is the relevant source code:

lvm2/lib/metadata/thin_manip.c

Lines 413 to 428 in f70d97b

	if (sz != UINT64_C(~0)) {
	log_warn("WARNING: Sum of all thin volume sizes (%s) exceeds the "
	"size of thin pool%s%s%s (%s).",
	display_size(cmd, thinsum),
	more_pools ? "" : " ",
	more_pools ? "s" : display_lvname(pool_lv),
	txt,
	(sz > 0) ? display_size(cmd, sz) : "no free space in volume group");
	if (max_threshold > 99 || !min_percent)
	log_print_unless_silent("WARNING: You have not turned on protection against thin pools running out of space.");
	if (max_threshold > 99)
	log_print_unless_silent("WARNING: Set activation/thin_pool_autoextend_threshold below 100 to trigger automatic extension of thin pools before they get full.");
	if (!min_percent)
	log_print_unless_silent("WARNING: Set activation/thin_pool_autoextend_percent above 0 to specify by how much to extend thin pools reaching the threshold.");
	/* FIXME Also warn if there isn't sufficient free space for one pool extension to occur? */
	}

As you can see, the first warning is logged using a different method than the other three: log_warn vs log_print_unless_silent. A simple solution would be to make all four of these warnings log_print_unless_silent. However, I think this is a suboptimal solution that may suppress other useful warnings throwing out the baby with the bathwater.

I have read what I think are all of the historical mailing list threads and forum threads on this particular topic. I have found one proposed fix that appears to be optimal for my use case: adding an envvar LVM_SUPPRESS_POOL_WARNINGS. This was proposed by @zkabelac here:
https://listman.redhat.com/archives/linux-lvm/2017-September/024332.html

As stated in that proposal, there are two precedents for this type of suppression that are already implemented in LVM2: LVM_SUPPRESS_FD_WARNINGS and LVM_SUPPRESS_LOCKING_FAILURE_MESSAGES.

Here are two historical threads about this feature request from the mailing list:
https://listman.redhat.com/archives/linux-lvm/2016-April/023529.html
https://listman.redhat.com/archives/linux-lvm/2017-September/024323.html

Here is an issue in the bugtracker at RedHat (unfortunately marked WONTFIX):
https://bugzilla.redhat.com/show_bug.cgi?id=1465974

Here is a forum thread over at Proxmox tracking this issue downstream:
https://forum.proxmox.com/threads/solved-you-have-not-turned-on-protection-against-thin-pools-running-out-of-space.91055/

I posted about this all to the lvm-linux mailing list, and there is interest in this change from the Qubes OS project and @DemiMarie:
https://listman.redhat.com/archives/linux-lvm/2022-May/026169.html

I am now going to suggest that all users and projects that want this change add a 👍 this issue so that there is a measurement of interest.

[utkonos]

I've done a bit more digging. These are the locations where messages/warnings are suppressed elsewhere:

LVM_SUPPRESS_LOCKING_FAILURE_MESSAGES

lvm2/lib/locking/locking.c

Lines 128 to 157 in 8dccc23

	int init_locking(struct cmd_context *cmd,
	int file_locking_sysinit, int file_locking_readonly, int file_locking_ignorefail)
	{
	int suppress_messages = 0;
	if (file_locking_sysinit || getenv("LVM_SUPPRESS_LOCKING_FAILURE_MESSAGES"))
	suppress_messages = 1;
	_blocking_supported = find_config_tree_bool(cmd, global_wait_for_locks_CFG, NULL);
	_file_locking_readonly = file_locking_readonly;
	_file_locking_sysinit = file_locking_sysinit;
	_file_locking_ignorefail = file_locking_ignorefail;
	log_debug("File locking settings: readonly:%d sysinit:%d ignorelockingfailure:%d global/metadata_read_only:%d global/wait_for_locks:%d.",
	_file_locking_readonly, _file_locking_sysinit, _file_locking_ignorefail,
	cmd->metadata_read_only, _blocking_supported);
	if (!init_file_locking(&_locking, cmd, suppress_messages)) {
	log_error_suppress(suppress_messages, "File locking initialisation failed.");
	_file_locking_failed = 1;
	if (file_locking_sysinit || file_locking_ignorefail)
	return 1;
	return 0;
	}
	return 1;
	}

LVM_SUPPRESS_FD_WARNINGS

lvm2/tools/lvmcmdline.c

Lines 3550 to 3586 in 8dccc23

	if (getenv("LVM_SUPPRESS_FD_WARNINGS"))
	suppress_warnings = 1;
	if (!(d = opendir(_fd_dir))) {
	if (errno != ENOENT) {
	log_sys_error("opendir", _fd_dir);
	return 0; /* broken system */
	}
	/* Path does not exist, use the old way */
	if (getrlimit(RLIMIT_NOFILE, &rlim) < 0) {
	log_sys_error("getrlimit", "RLIMIT_NOFILE");
	return 1;
	}
	for (fd = 3; fd < (int)rlim.rlim_cur; fd++) {
	if ((fd != custom_fds->out) &&
	(fd != custom_fds->err) &&
	(fd != custom_fds->report)) {
	_close_descriptor(fd, suppress_warnings, command, ppid,
	parent_cmdline);
	}
	}
	return 1;
	}
	while ((dirent = readdir(d))) {
	fd = atoi(dirent->d_name);
	if ((fd > 2) &&
	(fd != dirfd(d)) &&
	(fd != custom_fds->out) &&
	(fd != custom_fds->err) &&
	(fd != custom_fds->report)) {
	_close_descriptor(fd, suppress_warnings,
	command, ppid, parent_cmdline);
	}
	}

[utkonos]

Would this change do the trick?

if (sz != UINT64_C(~0)) { => if (sz != UINT64_C(~0) and !(getenv("LVM_SUPPRESS_POOL_WARNINGS"))) {

Is an envvar available in this way to thin_manip.c?