mount.h 3.5 KB
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/*
 *
 * Definitions for mount interface. This describes the in the kernel build 
 * linkedlist with mounted filesystems.
 *
 * Author:  Marco van Wieringen <mvw@planets.elm.net>
 *
 */
#ifndef _LINUX_MOUNT_H
#define _LINUX_MOUNT_H

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#include <linux/types.h>
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#include <linux/list.h>
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#include <linux/nodemask.h>
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#include <linux/spinlock.h>
#include <asm/atomic.h>

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struct super_block;
struct vfsmount;
struct dentry;
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struct mnt_namespace;
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#define MNT_NOSUID	0x01
#define MNT_NODEV	0x02
#define MNT_NOEXEC	0x04
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#define MNT_NOATIME	0x08
#define MNT_NODIRATIME	0x10
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#define MNT_RELATIME	0x20
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#define MNT_READONLY	0x40	/* does the user want this to be r/o? */
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#define MNT_SHRINKABLE	0x100
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#define MNT_IMBALANCED_WRITE_COUNT	0x200 /* just for debugging */
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#define MNT_SHARED	0x1000	/* if the vfsmount is a shared mount */
#define MNT_UNBINDABLE	0x2000	/* if the vfsmount is a unbindable mount */
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#define MNT_PNODE_MASK	0x3000	/* propagation flag mask */
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struct vfsmount {
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	struct list_head mnt_hash;
	struct vfsmount *mnt_parent;	/* fs we are mounted on */
	struct dentry *mnt_mountpoint;	/* dentry of mountpoint */
	struct dentry *mnt_root;	/* root of the mounted tree */
	struct super_block *mnt_sb;	/* pointer to superblock */
	struct list_head mnt_mounts;	/* list of children, anchored here */
	struct list_head mnt_child;	/* and going through their mnt_child */
	int mnt_flags;
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	/* 4 bytes hole on 64bits arches */
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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 */
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	struct list_head mnt_share;	/* circular list of shared mounts */
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	struct list_head mnt_slave_list;/* list of slave mounts */
	struct list_head mnt_slave;	/* slave list entry */
	struct vfsmount *mnt_master;	/* slave is on master->mnt_slave_list */
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	struct mnt_namespace *mnt_ns;	/* containing namespace */
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	int mnt_id;			/* mount identifier */
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	int mnt_group_id;		/* peer group identifier */
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	/*
	 * We put mnt_count & mnt_expiry_mark at the end of struct vfsmount
	 * to let these frequently modified fields in a separate cache line
	 * (so that reads of mnt_flags wont ping-pong on SMP machines)
	 */
	atomic_t mnt_count;
	int mnt_expiry_mark;		/* true if marked for expiry */
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	int mnt_pinned;
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	int mnt_ghosts;
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	/*
	 * This value is not stable unless all of the mnt_writers[] spinlocks
	 * are held, and all mnt_writer[]s on this mount have 0 as their ->count
	 */
	atomic_t __mnt_writers;
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};

static inline struct vfsmount *mntget(struct vfsmount *mnt)
{
	if (mnt)
		atomic_inc(&mnt->mnt_count);
	return mnt;
}

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extern int mnt_want_write(struct vfsmount *mnt);
extern void mnt_drop_write(struct vfsmount *mnt);
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extern void mntput_no_expire(struct vfsmount *mnt);
extern void mnt_pin(struct vfsmount *mnt);
extern void mnt_unpin(struct vfsmount *mnt);
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extern int __mnt_is_readonly(struct vfsmount *mnt);
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static inline void mntput(struct vfsmount *mnt)
{
	if (mnt) {
		mnt->mnt_expiry_mark = 0;
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		mntput_no_expire(mnt);
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	}
}

extern struct vfsmount *do_kern_mount(const char *fstype, int flags,
				      const char *name, void *data);

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struct file_system_type;
extern struct vfsmount *vfs_kern_mount(struct file_system_type *type,
				      int flags, const char *name,
				      void *data);

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struct nameidata;

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struct path;
extern int do_add_mount(struct vfsmount *newmnt, struct path *path,
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			int mnt_flags, struct list_head *fslist);

extern void mark_mounts_for_expiry(struct list_head *mounts);

extern spinlock_t vfsmount_lock;
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extern dev_t name_to_dev_t(char *name);
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#endif /* _LINUX_MOUNT_H */