path: root/fs/proc/namespaces.c
diff options
authorEric W. Biederman <ebiederm@xmission.com>2010-03-07 18:49:36 -0800
committerEric W. Biederman <ebiederm@xmission.com>2012-11-19 05:59:18 -0800
commit8823c079ba7136dc1948d6f6dcb5f8022bde438e (patch)
tree2b27b0a046d453c95c1b0490c0650ea586ef0f86 /fs/proc/namespaces.c
parenta85fb273c94648cbf20a5f9bcf8bbbb075f271ad (diff)
vfs: Add setns support for the mount namespace
setns support for the mount namespace is a little tricky as an arbitrary decision must be made about what to set fs->root and fs->pwd to, as there is no expectation of a relationship between the two mount namespaces. Therefore I arbitrarily find the root mount point, and follow every mount on top of it to find the top of the mount stack. Then I set fs->root and fs->pwd to that location. The topmost root of the mount stack seems like a reasonable place to be. Bind mount support for the mount namespace inodes has the possibility of creating circular dependencies between mount namespaces. Circular dependencies can result in loops that prevent mount namespaces from every being freed. I avoid creating those circular dependencies by adding a sequence number to the mount namespace and require all bind mounts be of a younger mount namespace into an older mount namespace. Add a helper function proc_ns_inode so it is possible to detect when we are attempting to bind mound a namespace inode. Acked-by: Serge Hallyn <serge.hallyn@canonical.com> Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Diffstat (limited to 'fs/proc/namespaces.c')
1 files changed, 5 insertions, 0 deletions
diff --git a/fs/proc/namespaces.c b/fs/proc/namespaces.c
index 85ca047e35f1..2a17fd9ae6a9 100644
--- a/fs/proc/namespaces.c
+++ b/fs/proc/namespaces.c
@@ -27,6 +27,7 @@ static const struct proc_ns_operations *ns_entries[] = {
+ &mntns_operations,
static const struct file_operations ns_file_operations = {
@@ -201,3 +202,7 @@ out_invalid:
return ERR_PTR(-EINVAL);
+bool proc_ns_inode(struct inode *inode)
+ return inode->i_fop == &ns_file_operations;