import: drop logic of setting up /var/lib/machines as btrfs loopback mount

Let's simplify things and drop the logic that /var/lib/machines is setup
as auto-growing btrfs loopback file /var/lib/machines.raw.

THis was done in order to make quota available for machine management,
but quite frankly never really worked properly, as we couldn't grow the
file system in sync with its use properly. Moreover philosophically it's
problematic overriding the admin's choice of file system like this.

Let's hence drop this, and simplify things. Deleting code is a good
feeling.

Now that regular file systems provide project quota we could probably
add per-machine quota support based on that, hence the btrfs quota
argument is not that interesting anymore (though btrfs quota is a bit
more powerful as it allows recursive quota, i.e. that the machine pool
gets an overall quota in addition to per-machine quota).

1 files changed, 6 insertions, 359 deletions

diff --git a/src/shared/machine-pool.c b/src/shared/machine-pool.c
index df56492e7b..de4f704252 100644
--- a/src/shared/machine-pool.c
+++ b/src/shared/machine-pool.c
@@ -1,46 +1,13 @@
 /* SPDX-License-Identifier: LGPL-2.1+ */
 
 #include <errno.h>
-#include <fcntl.h>
-#include <linux/loop.h>
-#include <signal.h>
-#include <stdbool.h>
-#include <stdio.h>
-#include <stdlib.h>
-#include <sys/file.h>
-#include <sys/ioctl.h>
-#include <sys/mount.h>
-#include <sys/prctl.h>
-#include <sys/stat.h>
 #include <sys/statfs.h>
-#include <sys/statvfs.h>
-#include <unistd.h>
 
-#include "sd-bus-protocol.h"
-#include "sd-bus.h"
-
-#include "alloc-util.h"
 #include "btrfs-util.h"
-#include "fd-util.h"
-#include "fileio.h"
-#include "fs-util.h"
 #include "label.h"
-#include "lockfile-util.h"
-#include "log.h"
 #include "machine-pool.h"
-#include "macro.h"
 #include "missing.h"
-#include "mkdir.h"
-#include "mount-util.h"
-#include "parse-util.h"
-#include "path-util.h"
-#include "process-util.h"
-#include "signal-util.h"
 #include "stat-util.h"
-#include "string-util.h"
-
-#define VAR_LIB_MACHINES_SIZE_START (1024UL*1024UL*500UL)
-#define VAR_LIB_MACHINES_FREE_MIN (1024UL*1024UL*750UL)
 
 static int check_btrfs(void) {
         struct statfs sfs;
@@ -56,344 +23,24 @@ static int check_btrfs(void) {
         return F_TYPE_EQUAL(sfs.f_type, BTRFS_SUPER_MAGIC);
 }
 
-static int setup_machine_raw(uint64_t size, sd_bus_error *error) {
-        _cleanup_free_ char *tmp = NULL;
-        _cleanup_close_ int fd = -1;
-        struct statvfs ss;
-        pid_t pid = 0;
+int setup_machine_directory(sd_bus_error *error) {
         int r;
 
-        /* We want to be able to make use of btrfs-specific file
-         * system features, in particular subvolumes, reflinks and
-         * quota. Hence, if we detect that /var/lib/machines.raw is
-         * not located on btrfs, let's create a loopback file, place a
-         * btrfs file system into it, and mount it to
-         * /var/lib/machines. */
-
-        fd = open("/var/lib/machines.raw", O_RDWR|O_CLOEXEC|O_NONBLOCK|O_NOCTTY);
-        if (fd >= 0)
-                return TAKE_FD(fd);
-
-        if (errno != ENOENT)
-                return sd_bus_error_set_errnof(error, errno, "Failed to open /var/lib/machines.raw: %m");
-
-        r = tempfn_xxxxxx("/var/lib/machines.raw", NULL, &tmp);
-        if (r < 0)
-                return r;
-
-        (void) mkdir_p_label("/var/lib", 0755);
-        fd = open(tmp, O_RDWR|O_CREAT|O_EXCL|O_NOCTTY|O_CLOEXEC, 0600);
-        if (fd < 0)
-                return sd_bus_error_set_errnof(error, errno, "Failed to create /var/lib/machines.raw: %m");
-
-        if (fstatvfs(fd, &ss) < 0) {
-                r = sd_bus_error_set_errnof(error, errno, "Failed to determine free space on /var/lib/machines.raw: %m");
-                goto fail;
-        }
-
-        if (ss.f_bsize * ss.f_bavail < VAR_LIB_MACHINES_FREE_MIN) {
-                r = sd_bus_error_setf(error, SD_BUS_ERROR_FAILED, "Not enough free disk space to set up /var/lib/machines.");
-                goto fail;
-        }
-
-        if (ftruncate(fd, size) < 0) {
-                r = sd_bus_error_set_errnof(error, errno, "Failed to enlarge /var/lib/machines.raw: %m");
-                goto fail;
-        }
-
-        r = safe_fork("(mkfs)", FORK_RESET_SIGNALS|FORK_DEATHSIG, &pid);
-        if (r < 0) {
-                sd_bus_error_set_errnof(error, r, "Failed to fork mkfs.btrfs: %m");
-                goto fail;
-        }
-        if (r == 0) {
-
-                /* Child */
-
-                fd = safe_close(fd);
-
-                execlp("mkfs.btrfs", "-Lvar-lib-machines", tmp, NULL);
-                if (errno == ENOENT)
-                        _exit(99);
-
-                _exit(EXIT_FAILURE);
-        }
-
-        r = wait_for_terminate_and_check("mkfs", pid, 0);
-        pid = 0;
-
-        if (r < 0) {
-                sd_bus_error_set_errnof(error, r, "Failed to wait for mkfs.btrfs: %m");
-                goto fail;
-        }
-        if (r == 99) {
-                r = sd_bus_error_set_errnof(error, ENOENT, "Cannot set up /var/lib/machines, mkfs.btrfs is missing");
-                goto fail;
-        }
-        if (r != EXIT_SUCCESS) {
-                r = sd_bus_error_setf(error, SD_BUS_ERROR_FAILED, "mkfs.btrfs failed with error code %i", r);
-                goto fail;
-        }
-
-        r = rename_noreplace(AT_FDCWD, tmp, AT_FDCWD, "/var/lib/machines.raw");
-        if (r < 0) {
-                sd_bus_error_set_errnof(error, r, "Failed to move /var/lib/machines.raw into place: %m");
-                goto fail;
-        }
-
-        return TAKE_FD(fd);
-
-fail:
-        unlink_noerrno(tmp);
-
-        if (pid > 1)
-                kill_and_sigcont(pid, SIGKILL);
-
-        return r;
-}
-
-int setup_machine_directory(uint64_t size, sd_bus_error *error) {
-        _cleanup_(release_lock_file) LockFile lock_file = LOCK_FILE_INIT;
-        struct loop_info64 info = {
-                .lo_flags = LO_FLAGS_AUTOCLEAR,
-        };
-        _cleanup_close_ int fd = -1, control = -1, loop = -1;
-        _cleanup_free_ char* loopdev = NULL;
-        char tmpdir[] = "/tmp/machine-pool.XXXXXX", *mntdir = NULL;
-        bool tmpdir_made = false, mntdir_made = false, mntdir_mounted = false;
-        char buf[FORMAT_BYTES_MAX];
-        int r, nr = -1;
-
-        /* btrfs cannot handle file systems < 16M, hence use this as minimum */
-        if (size == (uint64_t) -1)
-                size = VAR_LIB_MACHINES_SIZE_START;
-        else if (size < 16*1024*1024)
-                size = 16*1024*1024;
-
-        /* Make sure we only set the directory up once at a time */
-        r = make_lock_file("/run/systemd/machines.lock", LOCK_EX, &lock_file);
-        if (r < 0)
-                return r;
-
         r = check_btrfs();
         if (r < 0)
                 return sd_bus_error_set_errnof(error, r, "Failed to determine whether /var/lib/machines is located on btrfs: %m");
-        if (r > 0) {
-                (void) btrfs_subvol_make_label("/var/lib/machines");
-
-                r = btrfs_quota_enable("/var/lib/machines", true);
-                if (r < 0)
-                        log_warning_errno(r, "Failed to enable quota for /var/lib/machines, ignoring: %m");
-
-                r = btrfs_subvol_auto_qgroup("/var/lib/machines", 0, true);
-                if (r < 0)
-                        log_warning_errno(r, "Failed to set up default quota hierarchy for /var/lib/machines, ignoring: %m");
-
-                return 1;
-        }
-
-        if (path_is_mount_point("/var/lib/machines", NULL, AT_SYMLINK_FOLLOW) > 0) {
-                log_debug("/var/lib/machines is already a mount point, not creating loopback file for it.");
-                return 0;
-        }
-
-        r = dir_is_populated("/var/lib/machines");
-        if (r < 0 && r != -ENOENT)
-                return r;
-        if (r > 0) {
-                log_debug("/var/log/machines is already populated, not creating loopback file for it.");
-                return 0;
-        }
-
-        r = mkfs_exists("btrfs");
         if (r == 0)
-                return sd_bus_error_set_errnof(error, ENOENT, "Cannot set up /var/lib/machines, mkfs.btrfs is missing");
-        if (r < 0)
-                return r;
-
-        fd = setup_machine_raw(size, error);
-        if (fd < 0)
-                return fd;
-
-        control = open("/dev/loop-control", O_RDWR|O_CLOEXEC|O_NOCTTY|O_NONBLOCK);
-        if (control < 0)
-                return sd_bus_error_set_errnof(error, errno, "Failed to open /dev/loop-control: %m");
-
-        nr = ioctl(control, LOOP_CTL_GET_FREE);
-        if (nr < 0)
-                return sd_bus_error_set_errnof(error, errno, "Failed to allocate loop device: %m");
-
-        if (asprintf(&loopdev, "/dev/loop%i", nr) < 0) {
-                r = -ENOMEM;
-                goto fail;
-        }
-
-        loop = open(loopdev, O_CLOEXEC|O_RDWR|O_NOCTTY|O_NONBLOCK);
-        if (loop < 0) {
-                r = sd_bus_error_set_errnof(error, errno, "Failed to open loopback device: %m");
-                goto fail;
-        }
-
-        if (ioctl(loop, LOOP_SET_FD, fd) < 0) {
-                r = sd_bus_error_set_errnof(error, errno, "Failed to bind loopback device: %m");
-                goto fail;
-        }
-
-        if (ioctl(loop, LOOP_SET_STATUS64, &info) < 0) {
-                r = sd_bus_error_set_errnof(error, errno, "Failed to enable auto-clear for loopback device: %m");
-                goto fail;
-        }
-
-        /* We need to make sure the new /var/lib/machines directory
-         * has an access mode of 0700 at the time it is first made
-         * available. mkfs will create it with 0755 however. Hence,
-         * let's mount the directory into an inaccessible directory
-         * below /tmp first, fix the access mode, and move it to the
-         * public place then. */
-
-        if (!mkdtemp(tmpdir)) {
-                r = sd_bus_error_set_errnof(error, errno, "Failed to create temporary mount parent directory: %m");
-                goto fail;
-        }
-        tmpdir_made = true;
-
-        mntdir = strjoina(tmpdir, "/mnt");
-        if (mkdir(mntdir, 0700) < 0) {
-                r = sd_bus_error_set_errnof(error, errno, "Failed to create temporary mount directory: %m");
-                goto fail;
-        }
-        mntdir_made = true;
-
-        if (mount(loopdev, mntdir, "btrfs", 0, NULL) < 0) {
-                r = sd_bus_error_set_errnof(error, errno, "Failed to mount loopback device: %m");
-                goto fail;
-        }
-        mntdir_mounted = true;
-
-        r = btrfs_quota_enable(mntdir, true);
-        if (r < 0)
-                log_warning_errno(r, "Failed to enable quota, ignoring: %m");
-
-        r = btrfs_subvol_auto_qgroup(mntdir, 0, true);
-        if (r < 0)
-                log_warning_errno(r, "Failed to set up default quota hierarchy, ignoring: %m");
-
-        if (chmod(mntdir, 0700) < 0) {
-                r = sd_bus_error_set_errnof(error, errno, "Failed to fix owner: %m");
-                goto fail;
-        }
-
-        (void) mkdir_p_label("/var/lib/machines", 0700);
-
-        if (mount(mntdir, "/var/lib/machines", NULL, MS_BIND, NULL) < 0) {
-                r = sd_bus_error_set_errnof(error, errno, "Failed to mount directory into right place: %m");
-                goto fail;
-        }
-
-        (void) syncfs(fd);
-
-        log_info("Set up /var/lib/machines as btrfs loopback file system of size %s mounted on /var/lib/machines.raw.", format_bytes(buf, sizeof(buf), size));
-
-        (void) umount2(mntdir, MNT_DETACH);
-        (void) rmdir(mntdir);
-        (void) rmdir(tmpdir);
-
-        return 1;
-
-fail:
-        if (mntdir_mounted)
-                (void) umount2(mntdir, MNT_DETACH);
-
-        if (mntdir_made)
-                (void) rmdir(mntdir);
-        if (tmpdir_made)
-                (void) rmdir(tmpdir);
-
-        if (loop >= 0) {
-                (void) ioctl(loop, LOOP_CLR_FD);
-                loop = safe_close(loop);
-        }
-
-        (void) ioctl(control, LOOP_CTL_REMOVE, nr);
-
-        return r;
-}
-
-static int sync_path(const char *p) {
-        _cleanup_close_ int fd = -1;
-
-        fd = open(p, O_RDONLY|O_CLOEXEC|O_NOCTTY);
-        if (fd < 0)
-                return -errno;
-
-        if (syncfs(fd) < 0)
-                return -errno;
-
-        return 0;
-}
-
-int grow_machine_directory(void) {
-        char buf[FORMAT_BYTES_MAX];
-        struct statvfs a, b;
-        uint64_t old_size, new_size, max_add;
-        int r;
-
-        /* Ensure the disk space data is accurate */
-        sync_path("/var/lib/machines");
-        sync_path("/var/lib/machines.raw");
-
-        if (statvfs("/var/lib/machines.raw", &a) < 0)
-                return -errno;
-
-        if (statvfs("/var/lib/machines", &b) < 0)
-                return -errno;
-
-        /* Don't grow if not enough disk space is available on the host */
-        if (((uint64_t) a.f_bavail * (uint64_t) a.f_bsize) <= VAR_LIB_MACHINES_FREE_MIN)
-                return 0;
-
-        /* Don't grow if at least 1/3th of the fs is still free */
-        if (b.f_bavail > b.f_blocks / 3)
                 return 0;
 
-        /* Calculate how much we are willing to add at most */
-        max_add = ((uint64_t) a.f_bavail * (uint64_t) a.f_bsize) - VAR_LIB_MACHINES_FREE_MIN;
-
-        /* Calculate the old size */
-        old_size = (uint64_t) b.f_blocks * (uint64_t) b.f_bsize;
-
-        /* Calculate the new size as three times the size of what is used right now */
-        new_size = ((uint64_t) b.f_blocks - (uint64_t) b.f_bavail) * (uint64_t) b.f_bsize * 3;
-
-        /* Always, grow at least to the start size */
-        if (new_size < VAR_LIB_MACHINES_SIZE_START)
-                new_size = VAR_LIB_MACHINES_SIZE_START;
-
-        /* If the new size is smaller than the old size, don't grow */
-        if (new_size < old_size)
-                return 0;
-
-        /* Ensure we never add more than the maximum */
-        if (new_size > old_size + max_add)
-                new_size = old_size + max_add;
-
-        r = btrfs_resize_loopback("/var/lib/machines", new_size, true);
-        if (r < 0)
-                return log_debug_errno(r, "Failed to resize loopback: %m");
-        if (r == 0)
-                return 0;
+        (void) btrfs_subvol_make_label("/var/lib/machines");
 
-        /* Also bump the quota, of both the subvolume leaf qgroup, as
-         * well as of any subtree quota group by the same id but a
-         * higher level, if it exists. */
-        r = btrfs_qgroup_set_limit("/var/lib/machines", 0, new_size);
+        r = btrfs_quota_enable("/var/lib/machines", true);
         if (r < 0)
-                log_debug_errno(r, "Failed to set btrfs limit: %m");
+                log_warning_errno(r, "Failed to enable quota for /var/lib/machines, ignoring: %m");
 
-        r = btrfs_subvol_set_subtree_quota_limit("/var/lib/machines", 0, new_size);
+        r = btrfs_subvol_auto_qgroup("/var/lib/machines", 0, true);
         if (r < 0)
-                log_debug_errno(r, "Failed to set btrfs subtree limit: %m");
+                log_warning_errno(r, "Failed to set up default quota hierarchy for /var/lib/machines, ignoring: %m");
 
-        log_info("Grew /var/lib/machines btrfs loopback file system to %s.", format_bytes(buf, sizeof(buf), new_size));
         return 1;
 }