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 <stddef.h>
   7 #include <sys/types.h>
   8
   9 /* The limit used for /dev itself. 4MB should be enough since device nodes and symlinks don't
  10  * consume any space and udev isn't supposed to create regular file either. There's no limit on the
  11  * max number of inodes since such limit is hard to guess especially on large storage array
  12  * systems. */
  13 #define TMPFS_LIMITS_DEV             ",size=4m"
  14
  15 /* The limit used for /dev in private namespaces. 4MB for contents of regular files. The number of
  16  * inodes should be relatively low in private namespaces but for now use a 64k limit. */
  17 #define TMPFS_LIMITS_PRIVATE_DEV     ",size=4m,nr_inodes=64k"
  18
  19 /* Very little, if any use expected */
  20 #define TMPFS_LIMITS_EMPTY_OR_ALMOST ",size=4m,nr_inodes=1k"
  21 #define TMPFS_LIMITS_SYS             TMPFS_LIMITS_EMPTY_OR_ALMOST
  22 #define TMPFS_LIMITS_SYS_FS_CGROUP   TMPFS_LIMITS_EMPTY_OR_ALMOST
  23
  24 /* On an extremely small device with only 256MB of RAM, 20% of RAM should be enough for the re-execution of
  25  * PID1 because 16MB of free space is required. */
  26 #define TMPFS_LIMITS_RUN             ",size=20%,nr_inodes=800k"
  27
  28 /* The limit used for various nested tmpfs mounts, in particular for guests started by systemd-nspawn.
  29  * 10% of RAM (using 16GB of RAM as a baseline) translates to 400k inodes (assuming 4k each) and 25%
  30  * translates to 1M inodes.
  31  * (On the host, /tmp is configured through a .mount unit file.) */
  32 #define NESTED_TMPFS_LIMITS          ",size=10%,nr_inodes=400k"
  33
  34 /* More space for volatile root and /var */
  35 #define TMPFS_LIMITS_VAR             ",size=25%,nr_inodes=1m"
  36 #define TMPFS_LIMITS_ROOTFS          TMPFS_LIMITS_VAR
  37 #define TMPFS_LIMITS_VOLATILE_STATE  TMPFS_LIMITS_VAR
  38
  39 int name_to_handle_at_loop(int fd, const char *path, struct file_handle **ret_handle, int *ret_mnt_id, int flags);
  40
  41 int path_get_mnt_id_at_fallback(int dir_fd, const char *path, int *ret);
  42 int path_get_mnt_id_at(int dir_fd, const char *path, int *ret);
  43 static inline int path_get_mnt_id(const char *path, int *ret) {
  44         return path_get_mnt_id_at(AT_FDCWD, path, ret);
  45 }
  46
  47 int fd_is_mount_point(int fd, const char *filename, int flags);
  48 int path_is_mount_point_full(const char *path, const char *root, int flags);
  49 static inline int path_is_mount_point(const char *path) {
  50         return path_is_mount_point_full(path, NULL, 0);
  51 }
  52
  53 bool fstype_is_network(const char *fstype);
  54 bool fstype_needs_quota(const char *fstype);
  55 bool fstype_is_api_vfs(const char *fstype);
  56 bool fstype_is_blockdev_backed(const char *fstype);
  57 bool fstype_is_ro(const char *fsype);
  58 bool fstype_can_discard(const char *fstype);
  59 bool fstype_can_uid_gid(const char *fstype);
  60 bool fstype_can_umask(const char *fstype);
  61
  62 const char* fstype_norecovery_option(const char *fstype);
  63
  64 int dev_is_devtmpfs(void);
  65
  66 int mount_fd(const char *source, int target_fd, const char *filesystemtype, unsigned long mountflags, const void *data);
  67 int mount_nofollow(const char *source, const char *target, const char *filesystemtype, unsigned long mountflags, const void *data);
  68
  69 const char *mount_propagation_flag_to_string(unsigned long flags);
  70 int mount_propagation_flag_from_string(const char *name, unsigned long *ret);
  71 bool mount_propagation_flag_is_valid(unsigned long flag);
  72
  73 bool mount_new_api_supported(void);
  74 unsigned long ms_nosymfollow_supported(void);
  75
  76 int mount_option_supported(const char *fstype, const char *key, const char *value);
  77
  78 bool path_below_api_vfs(const char *p);