src/shared/mount-util.h

   1 /* SPDX-License-Identifier: LGPL-2.1+ */
   2 #pragma once
   3
   4 #include <mntent.h>
   5 #include <stdio.h>
   6 #include <unistd.h>
   7
   8 #include "errno-util.h"
   9 #include "macro.h"
  10
  11 /* 4MB for contents of regular files, 64k inodes for directories, symbolic links and device specials, using
  12  * large storage array systems as a baseline */
  13 #define TMPFS_LIMITS_DEV             ",size=4m,nr_inodes=64k"
  14
  15 /* Very little, if any use expected */
  16 #define TMPFS_LIMITS_EMPTY_OR_ALMOST ",size=4m,nr_inodes=1k"
  17 #define TMPFS_LIMITS_SYS             TMPFS_LIMITS_EMPTY_OR_ALMOST
  18 #define TMPFS_LIMITS_SYS_FS_CGROUP   TMPFS_LIMITS_EMPTY_OR_ALMOST
  19
  20 /* On an extremely small device with only 256MB of RAM, 20% of RAM should be enough for the re-execution of
  21  * PID1 because 16MB of free space is required. */
  22 #define TMPFS_LIMITS_RUN             ",size=20%,nr_inodes=800k"
  23
  24 /* The limit used for various nested tmpfs mounts, in paricular for guests started by systemd-nspawn.
  25  * 10% of RAM (using 16GB of RAM as a baseline) translates to 400k inodes (assuming 4k each) and 25%
  26  * translates to 1M inodes.
  27  * (On the host, /tmp is configured through a .mount unit file.) */
  28 #define NESTED_TMPFS_LIMITS          ",size=10%,nr_inodes=400k"
  29
  30 /* More space for volatile root and /var */
  31 #define TMPFS_LIMITS_VAR             ",size=25%,nr_inodes=1m"
  32 #define TMPFS_LIMITS_ROOTFS          TMPFS_LIMITS_VAR
  33 #define TMPFS_LIMITS_VOLATILE_STATE  TMPFS_LIMITS_VAR
  34
  35 int repeat_unmount(const char *path, int flags);
  36 int umount_recursive(const char *target, int flags);
  37 int bind_remount_recursive(const char *prefix, unsigned long new_flags, unsigned long flags_mask, char **deny_list);
  38 int bind_remount_recursive_with_mountinfo(const char *prefix, unsigned long new_flags, unsigned long flags_mask, char **deny_list, FILE *proc_self_mountinfo);
  39 int bind_remount_one_with_mountinfo(const char *path, unsigned long new_flags, unsigned long flags_mask, FILE *proc_self_mountinfo);
  40
  41 int mount_move_root(const char *path);
  42
  43 DEFINE_TRIVIAL_CLEANUP_FUNC(FILE*, endmntent);
  44 #define _cleanup_endmntent_ _cleanup_(endmntentp)
  45
  46 int mount_verbose(
  47                 int error_log_level,
  48                 const char *what,
  49                 const char *where,
  50                 const char *type,
  51                 unsigned long flags,
  52                 const char *options);
  53 int umount_verbose(const char *where);
  54
  55 int mount_option_mangle(
  56                 const char *options,
  57                 unsigned long mount_flags,
  58                 unsigned long *ret_mount_flags,
  59                 char **ret_remaining_options);
  60
  61 int mode_to_inaccessible_node(const char *runtime_dir, mode_t mode, char **dest);
  62
  63 /* Useful for usage with _cleanup_(), unmounts, removes a directory and frees the pointer */
  64 static inline void umount_and_rmdir_and_free(char *p) {
  65         PROTECT_ERRNO;
  66         (void) umount_recursive(p, 0);
  67         (void) rmdir(p);
  68         free(p);
  69 }
  70 DEFINE_TRIVIAL_CLEANUP_FUNC(char*, umount_and_rmdir_and_free);