src/basic/mountpoint-util.h

   1 /* SPDX-License-Identifier: LGPL-2.1-or-later */
   2 #pragma once
   3
   4 #include <fcntl.h>
   5 #include <stdbool.h>
   6 #include <sys/types.h>
   7
   8 /* The limit used for /dev itself. 4MB should be enough since device nodes and symlinks don't
   9  * consume any space and udev isn't supposed to create regular file either. There's no limit on the
  10  * max number of inodes since such limit is hard to guess especially on large storage array
  11  * systems. */
  12 #define TMPFS_LIMITS_DEV             ",size=4m"
  13
  14 /* The limit used for /dev in private namespaces. 4MB for contents of regular files. The number of
  15  * inodes should be relatively low in private namespaces but for now use a 64k limit. */
  16 #define TMPFS_LIMITS_PRIVATE_DEV     ",size=4m,nr_inodes=64k"
  17
  18 /* Very little, if any use expected */
  19 #define TMPFS_LIMITS_EMPTY_OR_ALMOST ",size=4m,nr_inodes=1k"
  20 #define TMPFS_LIMITS_SYS             TMPFS_LIMITS_EMPTY_OR_ALMOST
  21 #define TMPFS_LIMITS_SYS_FS_CGROUP   TMPFS_LIMITS_EMPTY_OR_ALMOST
  22
  23 /* On an extremely small device with only 256MB of RAM, 20% of RAM should be enough for the re-execution of
  24  * PID1 because 16MB of free space is required. */
  25 #define TMPFS_LIMITS_RUN             ",size=20%,nr_inodes=800k"
  26
  27 /* The limit used for various nested tmpfs mounts, in particular for guests started by systemd-nspawn.
  28  * 10% of RAM (using 16GB of RAM as a baseline) translates to 400k inodes (assuming 4k each) and 25%
  29  * translates to 1M inodes.
  30  * (On the host, /tmp is configured through a .mount unit file.) */
  31 #define NESTED_TMPFS_LIMITS          ",size=10%,nr_inodes=400k"
  32
  33 /* More space for volatile root and /var */
  34 #define TMPFS_LIMITS_VAR             ",size=25%,nr_inodes=1m"
  35 #define TMPFS_LIMITS_ROOTFS          TMPFS_LIMITS_VAR
  36 #define TMPFS_LIMITS_VOLATILE_STATE  TMPFS_LIMITS_VAR
  37
  38 int name_to_handle_at_loop(int fd, const char *path, struct file_handle **ret_handle, int *ret_mnt_id, int flags);
  39
  40 int path_get_mnt_id_at_fallback(int dir_fd, const char *path, int *ret);
  41 int path_get_mnt_id_at(int dir_fd, const char *path, int *ret);
  42 static inline int path_get_mnt_id(const char *path, int *ret) {
  43         return path_get_mnt_id_at(AT_FDCWD, path, ret);
  44 }
  45
  46 int fd_is_mount_point(int fd, const char *filename, int flags);
  47 int path_is_mount_point(const char *path, const char *root, int flags);
  48
  49 bool fstype_is_network(const char *fstype);
  50 bool fstype_needs_quota(const char *fstype);
  51 bool fstype_is_api_vfs(const char *fstype);
  52 bool fstype_is_blockdev_backed(const char *fstype);
  53 bool fstype_is_ro(const char *fsype);
  54 bool fstype_can_discard(const char *fstype);
  55 bool fstype_can_uid_gid(const char *fstype);
  56 bool fstype_can_norecovery(const char *fstype);
  57 bool fstype_can_umask(const char *fstype);
  58
  59 int dev_is_devtmpfs(void);
  60
  61 int mount_fd(const char *source, int target_fd, const char *filesystemtype, unsigned long mountflags, const void *data);
  62 int mount_nofollow(const char *source, const char *target, const char *filesystemtype, unsigned long mountflags, const void *data);
  63
  64 const char *mount_propagation_flag_to_string(unsigned long flags);
  65 int mount_propagation_flag_from_string(const char *name, unsigned long *ret);
  66 bool mount_propagation_flag_is_valid(unsigned long flag);
  67
  68 unsigned long ms_nosymfollow_supported(void);
  69
  70 int mount_option_supported(const char *fstype, const char *key, const char *value);