mount.h 3.85 KB
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/* SPDX-License-Identifier: GPL-2.0 */
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#include <linux/mount.h>
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#include <linux/seq_file.h>
#include <linux/poll.h>
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#include <linux/ns_common.h>
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#include <linux/fs_pin.h>
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struct mnt_namespace {
	atomic_t		count;
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	struct ns_common	ns;
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	struct mount *	root;
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	struct list_head	list;
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	struct user_namespace	*user_ns;
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	struct ucounts		*ucounts;
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	u64			seq;	/* Sequence number to prevent loops */
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	wait_queue_head_t poll;
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	u64 event;
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	unsigned int		mounts; /* # of mounts in the namespace */
	unsigned int		pending_mounts;
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} __randomize_layout;
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struct mnt_pcp {
	int mnt_count;
	int mnt_writers;
};

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struct mountpoint {
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	struct hlist_node m_hash;
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	struct dentry *m_dentry;
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	struct hlist_head m_list;
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	int m_count;
};

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struct mount {
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	struct hlist_node mnt_hash;
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	struct mount *mnt_parent;
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	struct dentry *mnt_mountpoint;
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	struct vfsmount mnt;
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	union {
		struct rcu_head mnt_rcu;
		struct llist_node mnt_llist;
	};
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#ifdef CONFIG_SMP
	struct mnt_pcp __percpu *mnt_pcp;
#else
	int mnt_count;
	int mnt_writers;
#endif
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	struct list_head mnt_mounts;	/* list of children, anchored here */
	struct list_head mnt_child;	/* and going through their mnt_child */
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	struct list_head mnt_instance;	/* mount instance on sb->s_mounts */
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	const char *mnt_devname;	/* Name of device e.g. /dev/dsk/hda1 */
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	struct list_head mnt_list;
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	struct list_head mnt_expire;	/* link in fs-specific expiry list */
	struct list_head mnt_share;	/* circular list of shared mounts */
	struct list_head mnt_slave_list;/* list of slave mounts */
	struct list_head mnt_slave;	/* slave list entry */
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	struct mount *mnt_master;	/* slave is on master->mnt_slave_list */
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	struct mnt_namespace *mnt_ns;	/* containing namespace */
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	struct mountpoint *mnt_mp;	/* where is it mounted */
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	struct hlist_node mnt_mp_list;	/* list mounts with the same mountpoint */
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	struct list_head mnt_umounting; /* list entry for umount propagation */
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#ifdef CONFIG_FSNOTIFY
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	struct fsnotify_mark_connector __rcu *mnt_fsnotify_marks;
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	__u32 mnt_fsnotify_mask;
#endif
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	int mnt_id;			/* mount identifier */
	int mnt_group_id;		/* peer group identifier */
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	int mnt_expiry_mark;		/* true if marked for expiry */
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	struct hlist_head mnt_pins;
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	struct fs_pin mnt_umount;
	struct dentry *mnt_ex_mountpoint;
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} __randomize_layout;
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#define MNT_NS_INTERNAL ERR_PTR(-EINVAL) /* distinct from any mnt_namespace */

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static inline struct mount *real_mount(struct vfsmount *mnt)
{
	return container_of(mnt, struct mount, mnt);
}

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static inline int mnt_has_parent(struct mount *mnt)
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{
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	return mnt != mnt->mnt_parent;
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}
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static inline int is_mounted(struct vfsmount *mnt)
{
	/* neither detached nor internal? */
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	return !IS_ERR_OR_NULL(real_mount(mnt)->mnt_ns);
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}

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extern struct mount *__lookup_mnt(struct vfsmount *, struct dentry *);
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extern int __legitimize_mnt(struct vfsmount *, unsigned);
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extern bool legitimize_mnt(struct vfsmount *, unsigned);

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static inline bool __path_is_mountpoint(const struct path *path)
{
	struct mount *m = __lookup_mnt(path->mnt, path->dentry);
	return m && likely(!(m->mnt.mnt_flags & MNT_SYNC_UMOUNT));
}

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extern void __detach_mounts(struct dentry *dentry);

static inline void detach_mounts(struct dentry *dentry)
{
	if (!d_mountpoint(dentry))
		return;
	__detach_mounts(dentry);
}

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static inline void get_mnt_ns(struct mnt_namespace *ns)
{
	atomic_inc(&ns->count);
}

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extern seqlock_t mount_lock;
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static inline void lock_mount_hash(void)
{
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	write_seqlock(&mount_lock);
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}

static inline void unlock_mount_hash(void)
{
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	write_sequnlock(&mount_lock);
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}

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struct proc_mounts {
	struct mnt_namespace *ns;
	struct path root;
	int (*show)(struct seq_file *, struct vfsmount *);
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	void *cached_mount;
	u64 cached_event;
	loff_t cached_index;
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};

extern const struct seq_operations mounts_op;
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extern bool __is_local_mountpoint(struct dentry *dentry);
static inline bool is_local_mountpoint(struct dentry *dentry)
{
	if (!d_mountpoint(dentry))
		return false;

	return __is_local_mountpoint(dentry);
}