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Commit 03e06e68 authored by Ram Pai's avatar Ram Pai Committed by Linus Torvalds
Browse files

[PATCH] introduce shared mounts 



This creates shared mounts.  A shared mount when bind-mounted to some
mountpoint, propagates mount/umount events to each other.  All the
shared mounts that propagate events to each other belong to the same
peer-group.

Signed-off-by: default avatarRam Pai <linuxram@us.ibm.com>
Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 07b20889

fs/namespace.c

+2 −1
Original line number Diff line number Diff line
@@ -68,6 +68,7 @@ struct vfsmount *alloc_vfsmnt(const char *name) 
		INIT_LIST_HEAD(&mnt->mnt_mounts);

		INIT_LIST_HEAD(&mnt->mnt_list);

		INIT_LIST_HEAD(&mnt->mnt_expire);

		INIT_LIST_HEAD(&mnt->mnt_share);

		if (name) {

			int size = strlen(name) + 1;

			char *newname = kmalloc(size, GFP_KERNEL);
@@ -1113,7 +1114,7 @@ long do_mount(char *dev_name, char *dir_name, char *type_page, 
				    data_page);

	else if (flags & MS_BIND)

		retval = do_loopback(&nd, dev_name, flags & MS_REC);

	else if (flags & MS_PRIVATE)

	else if (flags & (MS_SHARED | MS_PRIVATE))

		retval = do_change_type(&nd, flags);

	else if (flags & MS_MOVE)

		retval = do_move_mount(&nd, dev_name);

fs/pnode.c

+12 −1
Original line number Diff line number Diff line
@@ -11,7 +11,18 @@ 
#include <linux/fs.h>

#include "pnode.h"



/* return the next shared peer mount of @p */

static inline struct vfsmount *next_peer(struct vfsmount *p)

{

	return list_entry(p->mnt_share.next, struct vfsmount, mnt_share);

}



void change_mnt_propagation(struct vfsmount *mnt, int type)

{

	if (type == MS_SHARED) {

		mnt->mnt_flags |= MNT_SHARED;

	} else {

		list_del_init(&mnt->mnt_share);

		mnt->mnt_flags &= ~MNT_PNODE_MASK;

	}

}

fs/pnode.h

+4 −0
Original line number Diff line number Diff line
@@ -10,5 +10,9 @@ 


#include <linux/list.h>

#include <linux/mount.h>



#define IS_MNT_SHARED(mnt) (mnt->mnt_flags & MNT_SHARED)

#define CLEAR_MNT_SHARED(mnt) (mnt->mnt_flags &= ~MNT_SHARED)



void change_mnt_propagation(struct vfsmount *, int);

#endif /* _LINUX_PNODE_H */

include/linux/fs.h

+1 −0
Original line number Diff line number Diff line
@@ -105,6 +105,7 @@ extern int dir_notify_enable; 
#define MS_REC		16384

#define MS_VERBOSE	32768

#define MS_PRIVATE	(1<<18)	/* change to private */

#define MS_SHARED	(1<<20)	/* change to shared */

#define MS_POSIXACL	(1<<16)	/* VFS does not apply the umask */

#define MS_ACTIVE	(1<<30)

#define MS_NOUSER	(1<<31)

include/linux/mount.h

+2 −0
Original line number Diff line number Diff line
@@ -20,6 +20,7 @@ 
#define MNT_NOSUID	0x01

#define MNT_NODEV	0x02

#define MNT_NOEXEC	0x04

#define MNT_SHARED	0x10	/* if the vfsmount is a shared mount */

#define MNT_PNODE_MASK	0x30	/* propogation flag mask */



struct vfsmount {
@@ -36,6 +37,7 @@ struct vfsmount { 
	char *mnt_devname;		/* Name of device e.g. /dev/dsk/hda1 */

	struct list_head mnt_list;

	struct list_head mnt_expire;	/* link in fs-specific expiry list */

	struct list_head mnt_share;	/* circular list of shared mounts */

	struct namespace *mnt_namespace; /* containing namespace */

	int mnt_pinned;

};