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[PATCH] handling of slave mounts

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This makes bind, rbind, move, clone namespace and umount operations
aware of the semantics of slave mount (see Documentation/sharedsubtree.txt
in the last patch of the series for detailed description).

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>
This commit is contained in:
Ram Pai 2005-11-07 17:21:01 -05:00 • committed by Linus Torvalds
parent a58b0eb8e6
commit 5afe002213
2 changed files with 121 additions and 37 deletions
Download patch file Download diff file Expand all files Collapse all files

77
fs/namespace.c
View file

@ -227,8 +227,17 @@ static struct vfsmount *clone_mnt(struct vfsmount *old, struct dentry *root,
mnt->mnt_mountpoint = mnt->mnt_root;
mnt->mnt_parent = mnt;
if ((flag & CL_PROPAGATION) || IS_MNT_SHARED(old))
list_add(&mnt->mnt_share, &old->mnt_share);
if (flag & CL_SLAVE) {
list_add(&mnt->mnt_slave, &old->mnt_slave_list);
mnt->mnt_master = old;
CLEAR_MNT_SHARED(mnt);
} else {
if ((flag & CL_PROPAGATION) || IS_MNT_SHARED(old))
list_add(&mnt->mnt_share, &old->mnt_share);
if (IS_MNT_SLAVE(old))
list_add(&mnt->mnt_slave, &old->mnt_slave);
mnt->mnt_master = old->mnt_master;
}
if (flag & CL_MAKE_SHARED)
set_mnt_shared(mnt);
@ -689,18 +698,18 @@ Enomem:
*
* NOTE: in the table below explains the semantics when a source mount
* of a given type is attached to a destination mount of a given type.
* ---------------------------------------------
* | BIND MOUNT OPERATION |
* |********************************************
* | source-->| shared | private |
* | dest | | |
* | | | | |
* | v | | |
* |********************************************
* | shared | shared (++) | shared (+) |
* | | | |
* |non-shared| shared (+) | private |
* *********************************************
* -------------------------------------------------------------
* | BIND MOUNT OPERATION |
* |*************************************************************
* | source-->| shared | private | slave |
* | dest | | | |
* | | | | | |
* | v | | | |
* |*************************************************************
* | shared | shared (++) | shared (+) | shared(+++)|
* | | | | |
* |non-shared| shared (+) | private | slave (*) |
* **************************************************************
* A bind operation clones the source mount and mounts the clone on the
* destination mount.
*
@ -710,21 +719,33 @@ Enomem:
* (+) the cloned mount is created under the destination mount and is marked
* as shared. The cloned mount is added to the peer group of the source
* mount.
* ---------------------------------------------
* | MOVE MOUNT OPERATION |
* |********************************************
* | source-->| shared | private |
* | dest | | |
* | | | | |
* | v | | |
* |********************************************
* | shared | shared (+) | shared (+) |
* | | | |
* |non-shared| shared (+*) | private |
* *********************************************
* (+) the mount is moved to the destination. And is then propagated to all
* the mounts in the propagation tree of the destination mount.
* (+++) the mount is propagated to all the mounts in the propagation tree
* of the destination mount and the cloned mount is made slave
* of the same master as that of the source mount. The cloned mount
* is marked as 'shared and slave'.
* (*) the cloned mount is made a slave of the same master as that of the
* source mount.
*
* --------------------------------------------------------------
* | MOVE MOUNT OPERATION |
* |*************************************************************
* | source-->| shared | private | slave |
* | dest | | | |
* | | | | | |
* | v | | | |
* |*************************************************************
* | shared | shared (+) | shared (+) | shared(+++) |
* | | | | |
* |non-shared| shared (+*) | private | slave (*) |
* **************************************************************
*
* (+) the mount is moved to the destination. And is then propagated to
* all the mounts in the propagation tree of the destination mount.
* (+*) the mount is moved to the destination.
* (+++) the mount is moved to the destination and is then propagated to
* all the mounts belonging to the destination mount's propagation tree.
* the mount is marked as 'shared and slave'.
* (*) the mount continues to be a slave at the new location.
*
* if the source mount is a tree, the operations explained above is
* applied to each mount in the tree.