1/* SPDX-License-Identifier: GPL-2.0 */
2#ifndef _LINUX_FS_SUPER_TYPES_H
3#define _LINUX_FS_SUPER_TYPES_H
4
5#include <linux/fs_dirent.h>
6#include <linux/errseq.h>
7#include <linux/list_lru.h>
8#include <linux/list.h>
9#include <linux/list_bl.h>
10#include <linux/llist.h>
11#include <linux/uidgid.h>
12#include <linux/uuid.h>
13#include <linux/percpu-rwsem.h>
14#include <linux/workqueue_types.h>
15#include <linux/quota.h>
16
17struct backing_dev_info;
18struct block_device;
19struct dentry;
20struct dentry_operations;
21struct dquot_operations;
22struct export_operations;
23struct file;
24struct file_system_type;
25struct fscrypt_operations;
26struct fsnotify_sb_info;
27struct fsverity_operations;
28struct kstatfs;
29struct mount;
30struct mtd_info;
31struct quotactl_ops;
32struct shrinker;
33struct unicode_map;
34struct user_namespace;
35struct workqueue_struct;
36struct writeback_control;
37struct xattr_handler;
38
39extern struct super_block *blockdev_superblock;
40
41/* Possible states of 'frozen' field */
42enum {
43 SB_UNFROZEN = 0, /* FS is unfrozen */
44 SB_FREEZE_WRITE = 1, /* Writes, dir ops, ioctls frozen */
45 SB_FREEZE_PAGEFAULT = 2, /* Page faults stopped as well */
46 SB_FREEZE_FS = 3, /* For internal FS use (e.g. to stop internal threads if needed) */
47 SB_FREEZE_COMPLETE = 4, /* ->freeze_fs finished successfully */
48};
49
50#define SB_FREEZE_LEVELS (SB_FREEZE_COMPLETE - 1)
51
52struct sb_writers {
53 unsigned short frozen; /* Is sb frozen? */
54 int freeze_kcount; /* How many kernel freeze requests? */
55 int freeze_ucount; /* How many userspace freeze requests? */
56 const void *freeze_owner; /* Owner of the freeze */
57 struct percpu_rw_semaphore rw_sem[SB_FREEZE_LEVELS];
58};
59
60/**
61 * enum freeze_holder - holder of the freeze
62 * @FREEZE_HOLDER_KERNEL: kernel wants to freeze or thaw filesystem
63 * @FREEZE_HOLDER_USERSPACE: userspace wants to freeze or thaw filesystem
64 * @FREEZE_MAY_NEST: whether nesting freeze and thaw requests is allowed
65 * @FREEZE_EXCL: a freeze that can only be undone by the owner
66 *
67 * Indicate who the owner of the freeze or thaw request is and whether
68 * the freeze needs to be exclusive or can nest.
69 * Without @FREEZE_MAY_NEST, multiple freeze and thaw requests from the
70 * same holder aren't allowed. It is however allowed to hold a single
71 * @FREEZE_HOLDER_USERSPACE and a single @FREEZE_HOLDER_KERNEL freeze at
72 * the same time. This is relied upon by some filesystems during online
73 * repair or similar.
74 */
75enum freeze_holder {
76 FREEZE_HOLDER_KERNEL = (1U << 0),
77 FREEZE_HOLDER_USERSPACE = (1U << 1),
78 FREEZE_MAY_NEST = (1U << 2),
79 FREEZE_EXCL = (1U << 3),
80};
81
82struct super_operations {
83 struct inode *(*alloc_inode)(struct super_block *sb);
84 void (*destroy_inode)(struct inode *inode);
85 void (*free_inode)(struct inode *inode);
86 void (*dirty_inode)(struct inode *inode, int flags);
87 int (*write_inode)(struct inode *inode, struct writeback_control *wbc);
88 int (*drop_inode)(struct inode *inode);
89 void (*evict_inode)(struct inode *inode);
90 void (*put_super)(struct super_block *sb);
91 int (*sync_fs)(struct super_block *sb, int wait);
92 int (*freeze_super)(struct super_block *sb, enum freeze_holder who,
93 const void *owner);
94 int (*freeze_fs)(struct super_block *sb);
95 int (*thaw_super)(struct super_block *sb, enum freeze_holder who,
96 const void *owner);
97 int (*unfreeze_fs)(struct super_block *sb);
98 int (*statfs)(struct dentry *dentry, struct kstatfs *kstatfs);
99 int (*remount_fs) (struct super_block *, int *, char *);
100 void (*umount_begin)(struct super_block *sb);
101
102 int (*show_options)(struct seq_file *seq, struct dentry *dentry);
103 int (*show_devname)(struct seq_file *seq, struct dentry *dentry);
104 int (*show_path)(struct seq_file *seq, struct dentry *dentry);
105 int (*show_stats)(struct seq_file *seq, struct dentry *dentry);
106#ifdef CONFIG_QUOTA
107 ssize_t (*quota_read)(struct super_block *sb, int type, char *data,
108 size_t len, loff_t off);
109 ssize_t (*quota_write)(struct super_block *sb, int type,
110 const char *data, size_t len, loff_t off);
111 struct dquot __rcu **(*get_dquots)(struct inode *inode);
112#endif
113 long (*nr_cached_objects)(struct super_block *sb,
114 struct shrink_control *sc);
115 long (*free_cached_objects)(struct super_block *sb,
116 struct shrink_control *sc);
117 /*
118 * If a filesystem can support graceful removal of a device and
119 * continue read-write operations, implement this callback.
120 *
121 * Return 0 if the filesystem can continue read-write.
122 * Non-zero return value or no such callback means the fs will be shutdown
123 * as usual.
124 */
125 int (*remove_bdev)(struct super_block *sb, struct block_device *bdev);
126 void (*shutdown)(struct super_block *sb);
127};
128
129struct super_block {
130 struct list_head s_list; /* Keep this first */
131 dev_t s_dev; /* search index; _not_ kdev_t */
132 unsigned char s_blocksize_bits;
133 unsigned long s_blocksize;
134 loff_t s_maxbytes; /* Max file size */
135 struct file_system_type *s_type;
136 const struct super_operations *s_op;
137 const struct dquot_operations *dq_op;
138 const struct quotactl_ops *s_qcop;
139 const struct export_operations *s_export_op;
140 unsigned long s_flags;
141 unsigned long s_iflags; /* internal SB_I_* flags */
142 unsigned long s_magic;
143 struct dentry *s_root;
144 struct rw_semaphore s_umount;
145 int s_count;
146 atomic_t s_active;
147#ifdef CONFIG_SECURITY
148 void *s_security;
149#endif
150 const struct xattr_handler *const *s_xattr;
151#ifdef CONFIG_FS_ENCRYPTION
152 const struct fscrypt_operations *s_cop;
153 struct fscrypt_keyring *s_master_keys; /* master crypto keys in use */
154#endif
155#ifdef CONFIG_FS_VERITY
156 const struct fsverity_operations *s_vop;
157#endif
158#if IS_ENABLED(CONFIG_UNICODE)
159 struct unicode_map *s_encoding;
160 __u16 s_encoding_flags;
161#endif
162 struct hlist_bl_head s_roots; /* alternate root dentries for NFS */
163 struct mount *s_mounts; /* list of mounts; _not_ for fs use */
164 struct block_device *s_bdev; /* can go away once we use an accessor for @s_bdev_file */
165 struct file *s_bdev_file;
166 struct backing_dev_info *s_bdi;
167 struct mtd_info *s_mtd;
168 struct hlist_node s_instances;
169 unsigned int s_quota_types; /* Bitmask of supported quota types */
170 struct quota_info s_dquot; /* Diskquota specific options */
171
172 struct sb_writers s_writers;
173
174 /*
175 * Keep s_fs_info, s_time_gran, s_fsnotify_mask, and
176 * s_fsnotify_info together for cache efficiency. They are frequently
177 * accessed and rarely modified.
178 */
179 void *s_fs_info; /* Filesystem private info */
180
181 /* Granularity of c/m/atime in ns (cannot be worse than a second) */
182 u32 s_time_gran;
183 /* Time limits for c/m/atime in seconds */
184 time64_t s_time_min;
185 time64_t s_time_max;
186#ifdef CONFIG_FSNOTIFY
187 u32 s_fsnotify_mask;
188 struct fsnotify_sb_info *s_fsnotify_info;
189#endif
190
191 /*
192 * q: why are s_id and s_sysfs_name not the same? both are human
193 * readable strings that identify the filesystem
194 * a: s_id is allowed to change at runtime; it's used in log messages,
195 * and we want to when a device starts out as single device (s_id is dev
196 * name) but then a device is hot added and we have to switch to
197 * identifying it by UUID
198 * but s_sysfs_name is a handle for programmatic access, and can't
199 * change at runtime
200 */
201 char s_id[32]; /* Informational name */
202 uuid_t s_uuid; /* UUID */
203 u8 s_uuid_len; /* Default 16, possibly smaller for weird filesystems */
204
205 /* if set, fs shows up under sysfs at /sys/fs/$FSTYP/s_sysfs_name */
206 char s_sysfs_name[UUID_STRING_LEN + 1];
207
208 unsigned int s_max_links;
209 unsigned int s_d_flags; /* default d_flags for dentries */
210
211 /*
212 * The next field is for VFS *only*. No filesystems have any business
213 * even looking at it. You had been warned.
214 */
215 struct mutex s_vfs_rename_mutex; /* Kludge */
216
217 /*
218 * Filesystem subtype. If non-empty the filesystem type field
219 * in /proc/mounts will be "type.subtype"
220 */
221 const char *s_subtype;
222
223 const struct dentry_operations *__s_d_op; /* default d_op for dentries */
224
225 struct shrinker *s_shrink; /* per-sb shrinker handle */
226
227 /* Number of inodes with nlink == 0 but still referenced */
228 atomic_long_t s_remove_count;
229
230 /* Read-only state of the superblock is being changed */
231 int s_readonly_remount;
232
233 /* per-sb errseq_t for reporting writeback errors via syncfs */
234 errseq_t s_wb_err;
235
236 /* AIO completions deferred from interrupt context */
237 struct workqueue_struct *s_dio_done_wq;
238 struct hlist_head s_pins;
239
240 /*
241 * Owning user namespace and default context in which to
242 * interpret filesystem uids, gids, quotas, device nodes,
243 * xattrs and security labels.
244 */
245 struct user_namespace *s_user_ns;
246
247 /*
248 * The list_lru structure is essentially just a pointer to a table
249 * of per-node lru lists, each of which has its own spinlock.
250 * There is no need to put them into separate cachelines.
251 */
252 struct list_lru s_dentry_lru;
253 struct list_lru s_inode_lru;
254 struct rcu_head rcu;
255 struct work_struct destroy_work;
256
257 struct mutex s_sync_lock; /* sync serialisation lock */
258
259 /*
260 * Indicates how deep in a filesystem stack this SB is
261 */
262 int s_stack_depth;
263
264 /* s_inode_list_lock protects s_inodes */
265 spinlock_t s_inode_list_lock ____cacheline_aligned_in_smp;
266 struct list_head s_inodes; /* all inodes */
267
268 spinlock_t s_inode_wblist_lock;
269 struct list_head s_inodes_wb; /* writeback inodes */
270 long s_min_writeback_pages;
271} __randomize_layout;
272
273/*
274 * sb->s_flags. Note that these mirror the equivalent MS_* flags where
275 * represented in both.
276 */
277#define SB_RDONLY BIT(0) /* Mount read-only */
278#define SB_NOSUID BIT(1) /* Ignore suid and sgid bits */
279#define SB_NODEV BIT(2) /* Disallow access to device special files */
280#define SB_NOEXEC BIT(3) /* Disallow program execution */
281#define SB_SYNCHRONOUS BIT(4) /* Writes are synced at once */
282#define SB_MANDLOCK BIT(6) /* Allow mandatory locks on an FS */
283#define SB_DIRSYNC BIT(7) /* Directory modifications are synchronous */
284#define SB_NOATIME BIT(10) /* Do not update access times. */
285#define SB_NODIRATIME BIT(11) /* Do not update directory access times */
286#define SB_SILENT BIT(15)
287#define SB_POSIXACL BIT(16) /* Supports POSIX ACLs */
288#define SB_INLINECRYPT BIT(17) /* Use blk-crypto for encrypted files */
289#define SB_KERNMOUNT BIT(22) /* this is a kern_mount call */
290#define SB_I_VERSION BIT(23) /* Update inode I_version field */
291#define SB_LAZYTIME BIT(25) /* Update the on-disk [acm]times lazily */
292
293/* These sb flags are internal to the kernel */
294#define SB_DEAD BIT(21)
295#define SB_DYING BIT(24)
296#define SB_FORCE BIT(27)
297#define SB_NOSEC BIT(28)
298#define SB_BORN BIT(29)
299#define SB_ACTIVE BIT(30)
300#define SB_NOUSER BIT(31)
301
302/* These flags relate to encoding and casefolding */
303#define SB_ENC_STRICT_MODE_FL (1 << 0)
304#define SB_ENC_NO_COMPAT_FALLBACK_FL (1 << 1)
305
306#define sb_has_strict_encoding(sb) \
307 (sb->s_encoding_flags & SB_ENC_STRICT_MODE_FL)
308
309#if IS_ENABLED(CONFIG_UNICODE)
310#define sb_no_casefold_compat_fallback(sb) \
311 (sb->s_encoding_flags & SB_ENC_NO_COMPAT_FALLBACK_FL)
312#else
313#define sb_no_casefold_compat_fallback(sb) (1)
314#endif
315
316/* sb->s_iflags */
317#define SB_I_CGROUPWB 0x00000001 /* cgroup-aware writeback enabled */
318#define SB_I_NOEXEC 0x00000002 /* Ignore executables on this fs */
319#define SB_I_NODEV 0x00000004 /* Ignore devices on this fs */
320#define SB_I_STABLE_WRITES 0x00000008 /* don't modify blks until WB is done */
321
322/* sb->s_iflags to limit user namespace mounts */
323#define SB_I_USERNS_VISIBLE 0x00000010 /* fstype already mounted */
324#define SB_I_IMA_UNVERIFIABLE_SIGNATURE 0x00000020
325#define SB_I_UNTRUSTED_MOUNTER 0x00000040
326#define SB_I_EVM_HMAC_UNSUPPORTED 0x00000080
327
328#define SB_I_SKIP_SYNC 0x00000100 /* Skip superblock at global sync */
329#define SB_I_PERSB_BDI 0x00000200 /* has a per-sb bdi */
330#define SB_I_TS_EXPIRY_WARNED 0x00000400 /* warned about timestamp range expiry */
331#define SB_I_RETIRED 0x00000800 /* superblock shouldn't be reused */
332#define SB_I_NOUMASK 0x00001000 /* VFS does not apply umask */
333#define SB_I_NOIDMAP 0x00002000 /* No idmapped mounts on this superblock */
334#define SB_I_ALLOW_HSM 0x00004000 /* Allow HSM events on this superblock */
335
336#endif /* _LINUX_FS_SUPER_TYPES_H */
337

source code of linux/include/linux/fs/super_types.h