diff options
Diffstat (limited to 'include/linux/fs')
| -rw-r--r-- | include/linux/fs/super.h | 238 | ||||
| -rw-r--r-- | include/linux/fs/super_types.h | 336 |
2 files changed, 574 insertions, 0 deletions
diff --git a/include/linux/fs/super.h b/include/linux/fs/super.h new file mode 100644 index 000000000000..f21ffbb6dea5 --- /dev/null +++ b/include/linux/fs/super.h @@ -0,0 +1,238 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef _LINUX_FS_SUPER_H +#define _LINUX_FS_SUPER_H + +#include <linux/fs/super_types.h> +#include <linux/unicode.h> + +/* + * These are internal functions, please use sb_start_{write,pagefault,intwrite} + * instead. + */ +static inline void __sb_end_write(struct super_block *sb, int level) +{ + percpu_up_read(sb->s_writers.rw_sem + level - 1); +} + +static inline void __sb_start_write(struct super_block *sb, int level) +{ + percpu_down_read_freezable(sb->s_writers.rw_sem + level - 1, true); +} + +static inline bool __sb_start_write_trylock(struct super_block *sb, int level) +{ + return percpu_down_read_trylock(sb->s_writers.rw_sem + level - 1); +} + +#define __sb_writers_acquired(sb, lev) \ + percpu_rwsem_acquire(&(sb)->s_writers.rw_sem[(lev) - 1], 1, _THIS_IP_) +#define __sb_writers_release(sb, lev) \ + percpu_rwsem_release(&(sb)->s_writers.rw_sem[(lev) - 1], _THIS_IP_) + +/** + * __sb_write_started - check if sb freeze level is held + * @sb: the super we write to + * @level: the freeze level + * + * * > 0 - sb freeze level is held + * * 0 - sb freeze level is not held + * * < 0 - !CONFIG_LOCKDEP/LOCK_STATE_UNKNOWN + */ +static inline int __sb_write_started(const struct super_block *sb, int level) +{ + return lockdep_is_held_type(sb->s_writers.rw_sem + level - 1, 1); +} + +/** + * sb_write_started - check if SB_FREEZE_WRITE is held + * @sb: the super we write to + * + * May be false positive with !CONFIG_LOCKDEP/LOCK_STATE_UNKNOWN. + */ +static inline bool sb_write_started(const struct super_block *sb) +{ + return __sb_write_started(sb, SB_FREEZE_WRITE); +} + +/** + * sb_write_not_started - check if SB_FREEZE_WRITE is not held + * @sb: the super we write to + * + * May be false positive with !CONFIG_LOCKDEP/LOCK_STATE_UNKNOWN. + */ +static inline bool sb_write_not_started(const struct super_block *sb) +{ + return __sb_write_started(sb, SB_FREEZE_WRITE) <= 0; +} + +/** + * sb_end_write - drop write access to a superblock + * @sb: the super we wrote to + * + * Decrement number of writers to the filesystem. Wake up possible waiters + * wanting to freeze the filesystem. + */ +static inline void sb_end_write(struct super_block *sb) +{ + __sb_end_write(sb, SB_FREEZE_WRITE); +} + +/** + * sb_end_pagefault - drop write access to a superblock from a page fault + * @sb: the super we wrote to + * + * Decrement number of processes handling write page fault to the filesystem. + * Wake up possible waiters wanting to freeze the filesystem. + */ +static inline void sb_end_pagefault(struct super_block *sb) +{ + __sb_end_write(sb, SB_FREEZE_PAGEFAULT); +} + +/** + * sb_end_intwrite - drop write access to a superblock for internal fs purposes + * @sb: the super we wrote to + * + * Decrement fs-internal number of writers to the filesystem. Wake up possible + * waiters wanting to freeze the filesystem. + */ +static inline void sb_end_intwrite(struct super_block *sb) +{ + __sb_end_write(sb, SB_FREEZE_FS); +} + +/** + * sb_start_write - get write access to a superblock + * @sb: the super we write to + * + * When a process wants to write data or metadata to a file system (i.e. dirty + * a page or an inode), it should embed the operation in a sb_start_write() - + * sb_end_write() pair to get exclusion against file system freezing. This + * function increments number of writers preventing freezing. If the file + * system is already frozen, the function waits until the file system is + * thawed. + * + * Since freeze protection behaves as a lock, users have to preserve + * ordering of freeze protection and other filesystem locks. Generally, + * freeze protection should be the outermost lock. In particular, we have: + * + * sb_start_write + * -> i_rwsem (write path, truncate, directory ops, ...) + * -> s_umount (freeze_super, thaw_super) + */ +static inline void sb_start_write(struct super_block *sb) +{ + __sb_start_write(sb, SB_FREEZE_WRITE); +} + +DEFINE_GUARD(super_write, + struct super_block *, + sb_start_write(_T), + sb_end_write(_T)) + +static inline bool sb_start_write_trylock(struct super_block *sb) +{ + return __sb_start_write_trylock(sb, SB_FREEZE_WRITE); +} + +/** + * sb_start_pagefault - get write access to a superblock from a page fault + * @sb: the super we write to + * + * When a process starts handling write page fault, it should embed the + * operation into sb_start_pagefault() - sb_end_pagefault() pair to get + * exclusion against file system freezing. This is needed since the page fault + * is going to dirty a page. This function increments number of running page + * faults preventing freezing. If the file system is already frozen, the + * function waits until the file system is thawed. + * + * Since page fault freeze protection behaves as a lock, users have to preserve + * ordering of freeze protection and other filesystem locks. It is advised to + * put sb_start_pagefault() close to mmap_lock in lock ordering. Page fault + * handling code implies lock dependency: + * + * mmap_lock + * -> sb_start_pagefault + */ +static inline void sb_start_pagefault(struct super_block *sb) +{ + __sb_start_write(sb, SB_FREEZE_PAGEFAULT); +} + +/** + * sb_start_intwrite - get write access to a superblock for internal fs purposes + * @sb: the super we write to + * + * This is the third level of protection against filesystem freezing. It is + * free for use by a filesystem. The only requirement is that it must rank + * below sb_start_pagefault. + * + * For example filesystem can call sb_start_intwrite() when starting a + * transaction which somewhat eases handling of freezing for internal sources + * of filesystem changes (internal fs threads, discarding preallocation on file + * close, etc.). + */ +static inline void sb_start_intwrite(struct super_block *sb) +{ + __sb_start_write(sb, SB_FREEZE_FS); +} + +static inline bool sb_start_intwrite_trylock(struct super_block *sb) +{ + return __sb_start_write_trylock(sb, SB_FREEZE_FS); +} + +static inline bool sb_rdonly(const struct super_block *sb) +{ + return sb->s_flags & SB_RDONLY; +} + +static inline bool sb_is_blkdev_sb(struct super_block *sb) +{ + return IS_ENABLED(CONFIG_BLOCK) && sb == blockdev_superblock; +} + +#if IS_ENABLED(CONFIG_UNICODE) +static inline struct unicode_map *sb_encoding(const struct super_block *sb) +{ + return sb->s_encoding; +} + +/* Compare if two super blocks have the same encoding and flags */ +static inline bool sb_same_encoding(const struct super_block *sb1, + const struct super_block *sb2) +{ + if (sb1->s_encoding == sb2->s_encoding) + return true; + + return (sb1->s_encoding && sb2->s_encoding && + (sb1->s_encoding->version == sb2->s_encoding->version) && + (sb1->s_encoding_flags == sb2->s_encoding_flags)); +} +#else +static inline struct unicode_map *sb_encoding(const struct super_block *sb) +{ + return NULL; +} + +static inline bool sb_same_encoding(const struct super_block *sb1, + const struct super_block *sb2) +{ + return true; +} +#endif + +static inline bool sb_has_encoding(const struct super_block *sb) +{ + return !!sb_encoding(sb); +} + +int sb_set_blocksize(struct super_block *sb, int size); +int __must_check sb_min_blocksize(struct super_block *sb, int size); + +int freeze_super(struct super_block *super, enum freeze_holder who, + const void *freeze_owner); +int thaw_super(struct super_block *super, enum freeze_holder who, + const void *freeze_owner); + +#endif /* _LINUX_FS_SUPER_H */ diff --git a/include/linux/fs/super_types.h b/include/linux/fs/super_types.h new file mode 100644 index 000000000000..6bd3009e09b3 --- /dev/null +++ b/include/linux/fs/super_types.h @@ -0,0 +1,336 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef _LINUX_FS_SUPER_TYPES_H +#define _LINUX_FS_SUPER_TYPES_H + +#include <linux/fs_dirent.h> +#include <linux/errseq.h> +#include <linux/list_lru.h> +#include <linux/list.h> +#include <linux/list_bl.h> +#include <linux/llist.h> +#include <linux/uidgid.h> +#include <linux/uuid.h> +#include <linux/percpu-rwsem.h> +#include <linux/workqueue_types.h> +#include <linux/quota.h> + +struct backing_dev_info; +struct block_device; +struct dentry; +struct dentry_operations; +struct dquot_operations; +struct export_operations; +struct file; +struct file_system_type; +struct fscrypt_operations; +struct fsnotify_sb_info; +struct fsverity_operations; +struct kstatfs; +struct mount; +struct mtd_info; +struct quotactl_ops; +struct shrinker; +struct unicode_map; +struct user_namespace; +struct workqueue_struct; +struct writeback_control; +struct xattr_handler; + +extern struct super_block *blockdev_superblock; + +/* Possible states of 'frozen' field */ +enum { + SB_UNFROZEN = 0, /* FS is unfrozen */ + SB_FREEZE_WRITE = 1, /* Writes, dir ops, ioctls frozen */ + SB_FREEZE_PAGEFAULT = 2, /* Page faults stopped as well */ + SB_FREEZE_FS = 3, /* For internal FS use (e.g. to stop internal threads if needed) */ + SB_FREEZE_COMPLETE = 4, /* ->freeze_fs finished successfully */ +}; + +#define SB_FREEZE_LEVELS (SB_FREEZE_COMPLETE - 1) + +struct sb_writers { + unsigned short frozen; /* Is sb frozen? */ + int freeze_kcount; /* How many kernel freeze requests? */ + int freeze_ucount; /* How many userspace freeze requests? */ + const void *freeze_owner; /* Owner of the freeze */ + struct percpu_rw_semaphore rw_sem[SB_FREEZE_LEVELS]; +}; + +/** + * enum freeze_holder - holder of the freeze + * @FREEZE_HOLDER_KERNEL: kernel wants to freeze or thaw filesystem + * @FREEZE_HOLDER_USERSPACE: userspace wants to freeze or thaw filesystem + * @FREEZE_MAY_NEST: whether nesting freeze and thaw requests is allowed + * @FREEZE_EXCL: a freeze that can only be undone by the owner + * + * Indicate who the owner of the freeze or thaw request is and whether + * the freeze needs to be exclusive or can nest. + * Without @FREEZE_MAY_NEST, multiple freeze and thaw requests from the + * same holder aren't allowed. It is however allowed to hold a single + * @FREEZE_HOLDER_USERSPACE and a single @FREEZE_HOLDER_KERNEL freeze at + * the same time. This is relied upon by some filesystems during online + * repair or similar. + */ +enum freeze_holder { + FREEZE_HOLDER_KERNEL = (1U << 0), + FREEZE_HOLDER_USERSPACE = (1U << 1), + FREEZE_MAY_NEST = (1U << 2), + FREEZE_EXCL = (1U << 3), +}; + +struct super_operations { + struct inode *(*alloc_inode)(struct super_block *sb); + void (*destroy_inode)(struct inode *inode); + void (*free_inode)(struct inode *inode); + void (*dirty_inode)(struct inode *inode, int flags); + int (*write_inode)(struct inode *inode, struct writeback_control *wbc); + int (*drop_inode)(struct inode *inode); + void (*evict_inode)(struct inode *inode); + void (*put_super)(struct super_block *sb); + int (*sync_fs)(struct super_block *sb, int wait); + int (*freeze_super)(struct super_block *sb, enum freeze_holder who, + const void *owner); + int (*freeze_fs)(struct super_block *sb); + int (*thaw_super)(struct super_block *sb, enum freeze_holder who, + const void *owner); + int (*unfreeze_fs)(struct super_block *sb); + int (*statfs)(struct dentry *dentry, struct kstatfs *kstatfs); + int (*remount_fs) (struct super_block *, int *, char *); + void (*umount_begin)(struct super_block *sb); + + int (*show_options)(struct seq_file *seq, struct dentry *dentry); + int (*show_devname)(struct seq_file *seq, struct dentry *dentry); + int (*show_path)(struct seq_file *seq, struct dentry *dentry); + int (*show_stats)(struct seq_file *seq, struct dentry *dentry); +#ifdef CONFIG_QUOTA + ssize_t (*quota_read)(struct super_block *sb, int type, char *data, + size_t len, loff_t off); + ssize_t (*quota_write)(struct super_block *sb, int type, + const char *data, size_t len, loff_t off); + struct dquot __rcu **(*get_dquots)(struct inode *inode); +#endif + long (*nr_cached_objects)(struct super_block *sb, + struct shrink_control *sc); + long (*free_cached_objects)(struct super_block *sb, + struct shrink_control *sc); + /* + * If a filesystem can support graceful removal of a device and + * continue read-write operations, implement this callback. + * + * Return 0 if the filesystem can continue read-write. + * Non-zero return value or no such callback means the fs will be shutdown + * as usual. + */ + int (*remove_bdev)(struct super_block *sb, struct block_device *bdev); + void (*shutdown)(struct super_block *sb); +}; + +struct super_block { + struct list_head s_list; /* Keep this first */ + dev_t s_dev; /* search index; _not_ kdev_t */ + unsigned char s_blocksize_bits; + unsigned long s_blocksize; + loff_t s_maxbytes; /* Max file size */ + struct file_system_type *s_type; + const struct super_operations *s_op; + const struct dquot_operations *dq_op; + const struct quotactl_ops *s_qcop; + const struct export_operations *s_export_op; + unsigned long s_flags; + unsigned long s_iflags; /* internal SB_I_* flags */ + unsigned long s_magic; + struct dentry *s_root; + struct rw_semaphore s_umount; + int s_count; + atomic_t s_active; +#ifdef CONFIG_SECURITY + void *s_security; +#endif + const struct xattr_handler *const *s_xattr; +#ifdef CONFIG_FS_ENCRYPTION + const struct fscrypt_operations *s_cop; + struct fscrypt_keyring *s_master_keys; /* master crypto keys in use */ +#endif +#ifdef CONFIG_FS_VERITY + const struct fsverity_operations *s_vop; +#endif +#if IS_ENABLED(CONFIG_UNICODE) + struct unicode_map *s_encoding; + __u16 s_encoding_flags; +#endif + struct hlist_bl_head s_roots; /* alternate root dentries for NFS */ + struct mount *s_mounts; /* list of mounts; _not_ for fs use */ + struct block_device *s_bdev; /* can go away once we use an accessor for @s_bdev_file */ + struct file *s_bdev_file; + struct backing_dev_info *s_bdi; + struct mtd_info *s_mtd; + struct hlist_node s_instances; + unsigned int s_quota_types; /* Bitmask of supported quota types */ + struct quota_info s_dquot; /* Diskquota specific options */ + + struct sb_writers s_writers; + + /* + * Keep s_fs_info, s_time_gran, s_fsnotify_mask, and + * s_fsnotify_info together for cache efficiency. They are frequently + * accessed and rarely modified. + */ + void *s_fs_info; /* Filesystem private info */ + + /* Granularity of c/m/atime in ns (cannot be worse than a second) */ + u32 s_time_gran; + /* Time limits for c/m/atime in seconds */ + time64_t s_time_min; + time64_t s_time_max; +#ifdef CONFIG_FSNOTIFY + u32 s_fsnotify_mask; + struct fsnotify_sb_info *s_fsnotify_info; +#endif + + /* + * q: why are s_id and s_sysfs_name not the same? both are human + * readable strings that identify the filesystem + * a: s_id is allowed to change at runtime; it's used in log messages, + * and we want to when a device starts out as single device (s_id is dev + * name) but then a device is hot added and we have to switch to + * identifying it by UUID + * but s_sysfs_name is a handle for programmatic access, and can't + * change at runtime + */ + char s_id[32]; /* Informational name */ + uuid_t s_uuid; /* UUID */ + u8 s_uuid_len; /* Default 16, possibly smaller for weird filesystems */ + + /* if set, fs shows up under sysfs at /sys/fs/$FSTYP/s_sysfs_name */ + char s_sysfs_name[UUID_STRING_LEN + 1]; + + unsigned int s_max_links; + unsigned int s_d_flags; /* default d_flags for dentries */ + + /* + * The next field is for VFS *only*. No filesystems have any business + * even looking at it. You had been warned. + */ + struct mutex s_vfs_rename_mutex; /* Kludge */ + + /* + * Filesystem subtype. If non-empty the filesystem type field + * in /proc/mounts will be "type.subtype" + */ + const char *s_subtype; + + const struct dentry_operations *__s_d_op; /* default d_op for dentries */ + + struct shrinker *s_shrink; /* per-sb shrinker handle */ + + /* Number of inodes with nlink == 0 but still referenced */ + atomic_long_t s_remove_count; + + /* Read-only state of the superblock is being changed */ + int s_readonly_remount; + + /* per-sb errseq_t for reporting writeback errors via syncfs */ + errseq_t s_wb_err; + + /* AIO completions deferred from interrupt context */ + struct workqueue_struct *s_dio_done_wq; + struct hlist_head s_pins; + + /* + * Owning user namespace and default context in which to + * interpret filesystem uids, gids, quotas, device nodes, + * xattrs and security labels. + */ + struct user_namespace *s_user_ns; + + /* + * The list_lru structure is essentially just a pointer to a table + * of per-node lru lists, each of which has its own spinlock. + * There is no need to put them into separate cachelines. + */ + struct list_lru s_dentry_lru; + struct list_lru s_inode_lru; + struct rcu_head rcu; + struct work_struct destroy_work; + + struct mutex s_sync_lock; /* sync serialisation lock */ + + /* + * Indicates how deep in a filesystem stack this SB is + */ + int s_stack_depth; + + /* s_inode_list_lock protects s_inodes */ + spinlock_t s_inode_list_lock ____cacheline_aligned_in_smp; + struct list_head s_inodes; /* all inodes */ + + spinlock_t s_inode_wblist_lock; + struct list_head s_inodes_wb; /* writeback inodes */ + long s_min_writeback_pages; +} __randomize_layout; + +/* + * sb->s_flags. Note that these mirror the equivalent MS_* flags where + * represented in both. + */ +#define SB_RDONLY BIT(0) /* Mount read-only */ +#define SB_NOSUID BIT(1) /* Ignore suid and sgid bits */ +#define SB_NODEV BIT(2) /* Disallow access to device special files */ +#define SB_NOEXEC BIT(3) /* Disallow program execution */ +#define SB_SYNCHRONOUS BIT(4) /* Writes are synced at once */ +#define SB_MANDLOCK BIT(6) /* Allow mandatory locks on an FS */ +#define SB_DIRSYNC BIT(7) /* Directory modifications are synchronous */ +#define SB_NOATIME BIT(10) /* Do not update access times. */ +#define SB_NODIRATIME BIT(11) /* Do not update directory access times */ +#define SB_SILENT BIT(15) +#define SB_POSIXACL BIT(16) /* Supports POSIX ACLs */ +#define SB_INLINECRYPT BIT(17) /* Use blk-crypto for encrypted files */ +#define SB_KERNMOUNT BIT(22) /* this is a kern_mount call */ +#define SB_I_VERSION BIT(23) /* Update inode I_version field */ +#define SB_LAZYTIME BIT(25) /* Update the on-disk [acm]times lazily */ + +/* These sb flags are internal to the kernel */ +#define SB_DEAD BIT(21) +#define SB_DYING BIT(24) +#define SB_FORCE BIT(27) +#define SB_NOSEC BIT(28) +#define SB_BORN BIT(29) +#define SB_ACTIVE BIT(30) +#define SB_NOUSER BIT(31) + +/* These flags relate to encoding and casefolding */ +#define SB_ENC_STRICT_MODE_FL (1 << 0) +#define SB_ENC_NO_COMPAT_FALLBACK_FL (1 << 1) + +#define sb_has_strict_encoding(sb) \ + (sb->s_encoding_flags & SB_ENC_STRICT_MODE_FL) + +#if IS_ENABLED(CONFIG_UNICODE) +#define sb_no_casefold_compat_fallback(sb) \ + (sb->s_encoding_flags & SB_ENC_NO_COMPAT_FALLBACK_FL) +#else +#define sb_no_casefold_compat_fallback(sb) (1) +#endif + +/* sb->s_iflags */ +#define SB_I_CGROUPWB 0x00000001 /* cgroup-aware writeback enabled */ +#define SB_I_NOEXEC 0x00000002 /* Ignore executables on this fs */ +#define SB_I_NODEV 0x00000004 /* Ignore devices on this fs */ +#define SB_I_STABLE_WRITES 0x00000008 /* don't modify blks until WB is done */ + +/* sb->s_iflags to limit user namespace mounts */ +#define SB_I_USERNS_VISIBLE 0x00000010 /* fstype already mounted */ +#define SB_I_IMA_UNVERIFIABLE_SIGNATURE 0x00000020 +#define SB_I_UNTRUSTED_MOUNTER 0x00000040 +#define SB_I_EVM_HMAC_UNSUPPORTED 0x00000080 + +#define SB_I_SKIP_SYNC 0x00000100 /* Skip superblock at global sync */ +#define SB_I_PERSB_BDI 0x00000200 /* has a per-sb bdi */ +#define SB_I_TS_EXPIRY_WARNED 0x00000400 /* warned about timestamp range expiry */ +#define SB_I_RETIRED 0x00000800 /* superblock shouldn't be reused */ +#define SB_I_NOUMASK 0x00001000 /* VFS does not apply umask */ +#define SB_I_NOIDMAP 0x00002000 /* No idmapped mounts on this superblock */ +#define SB_I_ALLOW_HSM 0x00004000 /* Allow HSM events on this superblock */ + +#endif /* _LINUX_FS_SUPER_TYPES_H */ |