src/basic/mountpoint-util.h

   1 /* SPDX-License-Identifier: LGPL-2.1-or-later */
   2 #pragma once
   3
   4 #include "forward.h"
   5
   6 /* The limit used for /dev itself. 4MB should be enough since device nodes and symlinks don't
   7  * consume any space and udev isn't supposed to create regular file either. There's no limit on the
   8  * max number of inodes since such limit is hard to guess especially on large storage array
   9  * systems. */
  10 #define TMPFS_LIMITS_DEV             ",size=4m"
  11
  12 /* The limit used for /dev in private namespaces. 4MB for contents of regular files. The number of
  13  * inodes should be relatively low in private namespaces but for now use a 64k limit. */
  14 #define TMPFS_LIMITS_PRIVATE_DEV     ",size=4m,nr_inodes=64k"
  15
  16 /* Very little, if any use expected */
  17 #define TMPFS_LIMITS_EMPTY_OR_ALMOST ",size=4m,nr_inodes=1k"
  18 #define TMPFS_LIMITS_SYS             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 particular 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 bool is_name_to_handle_at_fatal_error(int err);
  36
  37 int name_to_handle_at_loop(int fd, const char *path, struct file_handle **ret_handle, int *ret_mnt_id, int flags);
  38 int name_to_handle_at_try_fid(int fd, const char *path, struct file_handle **ret_handle, int *ret_mnt_id, int flags);
  39
  40 bool file_handle_equal(const struct file_handle *a, const struct file_handle *b);
  41
  42 int path_get_mnt_id_at_fallback(int dir_fd, const char *path, int *ret);
  43 int path_get_mnt_id_at(int dir_fd, const char *path, int *ret);
  44 static inline int path_get_mnt_id(const char *path, int *ret) {
  45         return path_get_mnt_id_at(AT_FDCWD, path, ret);
  46 }
  47
  48 int is_mount_point_at(int fd, const char *filename, int flags);
  49 int path_is_mount_point_full(const char *path, const char *root, int flags);
  50 static inline int path_is_mount_point(const char *path) {
  51         return path_is_mount_point_full(path, NULL, 0);
  52 }
  53
  54 bool fstype_is_network(const char *fstype);
  55 bool fstype_needs_quota(const char *fstype);
  56 bool fstype_is_api_vfs(const char *fstype);
  57 bool fstype_is_blockdev_backed(const char *fstype);
  58 bool fstype_is_ro(const char *fsype);
  59 bool fstype_can_discard(const char *fstype);
  60 bool fstype_can_uid_gid(const char *fstype);
  61 bool fstype_can_fmask_dmask(const char *fstype);
  62
  63 const char* fstype_norecovery_option(const char *fstype);
  64
  65 int dev_is_devtmpfs(void);
  66
  67 int mount_nofollow(
  68                 const char *source,
  69                 const char *target,
  70                 const char *filesystemtype,
  71                 unsigned long mountflags,
  72                 const void *data);
  73
  74 const char* mount_propagation_flag_to_string(unsigned long flags);
  75 int mount_propagation_flag_from_string(const char *name, unsigned long *ret);
  76 bool mount_propagation_flag_is_valid(unsigned long flag);
  77
  78 bool mount_new_api_supported(void);
  79 unsigned long ms_nosymfollow_supported(void);
  80
  81 int mount_option_supported(const char *fstype, const char *key, const char *value);
  82
  83 bool path_below_api_vfs(const char *p);