9676f0c638
An unbindable mount does not forward or receive propagation. Also unbindable mount disallows bind mounts. The semantics is as follows. Bind semantics: It is invalid to bind mount an unbindable mount. Move semantics: It is invalid to move an unbindable mount under shared mount. Clone-namespace semantics: If a mount is unbindable in the parent namespace, the corresponding cloned mount in the child namespace becomes unbindable too. Note: there is subtle difference, unbindable mounts cannot be bind mounted but can be cloned during clone-namespace. Signed-off-by: Ram Pai <linuxram@us.ibm.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
85 lines
2.5 KiB
C
85 lines
2.5 KiB
C
/*
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*
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* Definitions for mount interface. This describes the in the kernel build
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* linkedlist with mounted filesystems.
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*
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* Author: Marco van Wieringen <mvw@planets.elm.net>
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*
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* Version: $Id: mount.h,v 2.0 1996/11/17 16:48:14 mvw Exp mvw $
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*
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*/
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#ifndef _LINUX_MOUNT_H
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#define _LINUX_MOUNT_H
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#ifdef __KERNEL__
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#include <linux/types.h>
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#include <linux/list.h>
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#include <linux/spinlock.h>
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#include <asm/atomic.h>
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#define MNT_NOSUID 0x01
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#define MNT_NODEV 0x02
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#define MNT_NOEXEC 0x04
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#define MNT_SHARED 0x10 /* if the vfsmount is a shared mount */
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#define MNT_UNBINDABLE 0x20 /* if the vfsmount is a unbindable mount */
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#define MNT_PNODE_MASK 0x30 /* propogation flag mask */
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struct vfsmount {
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struct list_head mnt_hash;
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struct vfsmount *mnt_parent; /* fs we are mounted on */
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struct dentry *mnt_mountpoint; /* dentry of mountpoint */
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struct dentry *mnt_root; /* root of the mounted tree */
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struct super_block *mnt_sb; /* pointer to superblock */
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struct list_head mnt_mounts; /* list of children, anchored here */
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struct list_head mnt_child; /* and going through their mnt_child */
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atomic_t mnt_count;
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int mnt_flags;
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int mnt_expiry_mark; /* true if marked for expiry */
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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 */
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struct list_head mnt_slave; /* slave list entry */
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struct vfsmount *mnt_master; /* slave is on master->mnt_slave_list */
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struct namespace *mnt_namespace; /* containing namespace */
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int mnt_pinned;
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};
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static inline struct vfsmount *mntget(struct vfsmount *mnt)
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{
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if (mnt)
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atomic_inc(&mnt->mnt_count);
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return mnt;
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}
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extern void mntput_no_expire(struct vfsmount *mnt);
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extern void mnt_pin(struct vfsmount *mnt);
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extern void mnt_unpin(struct vfsmount *mnt);
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static inline void mntput(struct vfsmount *mnt)
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{
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if (mnt) {
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mnt->mnt_expiry_mark = 0;
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mntput_no_expire(mnt);
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}
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}
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extern void free_vfsmnt(struct vfsmount *mnt);
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extern struct vfsmount *alloc_vfsmnt(const char *name);
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extern struct vfsmount *do_kern_mount(const char *fstype, int flags,
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const char *name, void *data);
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struct nameidata;
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extern int do_add_mount(struct vfsmount *newmnt, struct nameidata *nd,
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int mnt_flags, struct list_head *fslist);
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extern void mark_mounts_for_expiry(struct list_head *mounts);
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extern spinlock_t vfsmount_lock;
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extern dev_t name_to_dev_t(char *name);
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#endif
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#endif /* _LINUX_MOUNT_H */
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