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authorAl Viro <viro@zeniv.linux.org.uk>2014-11-01 10:57:28 -0400
committerAl Viro <viro@zeniv.linux.org.uk>2014-12-10 21:30:20 -0500
commite149ed2b805fefdccf7ccdfc19eca22fdd4514ac (patch)
tree8c9cd88deff8c7309ca2acb8d4cb475aaca47b14 /fs/namespace.c
parentf77c80142e1afe6d5c16975ca5d7d1fc324b16f9 (diff)
downloadlinux-e149ed2b805fefdccf7ccdfc19eca22fdd4514ac.tar.bz2
take the targets of /proc/*/ns/* symlinks to separate fs
New pseudo-filesystem: nsfs. Targets of /proc/*/ns/* live there now. It's not mountable (not even registered, so it's not in /proc/filesystems, etc.). Files on it *are* bindable - we explicitly permit that in do_loopback(). This stuff lives in fs/nsfs.c now; proc_ns_fget() moved there as well. get_proc_ns() is a macro now (it's simply returning ->i_private; would have been an inline, if not for header ordering headache). proc_ns_inode() is an ex-parrot. The interface used in procfs is ns_get_path(path, task, ops) and ns_get_name(buf, size, task, ops). Dentries and inodes are never hashed; a non-counting reference to dentry is stashed in ns_common (removed by ->d_prune()) and reused by ns_get_path() if present. See ns_get_path()/ns_prune_dentry/nsfs_evict() for details of that mechanism. As the result, proc_ns_follow_link() has stopped poking in nd->path.mnt; it does nd_jump_link() on a consistent <vfsmount,dentry> pair it gets from ns_get_path(). Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Diffstat (limited to 'fs/namespace.c')
-rw-r--r--fs/namespace.c9
1 files changed, 6 insertions, 3 deletions
diff --git a/fs/namespace.c b/fs/namespace.c
index 9dfb4cac0c41..30df6e7dd807 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -1569,8 +1569,8 @@ SYSCALL_DEFINE1(oldumount, char __user *, name)
static bool is_mnt_ns_file(struct dentry *dentry)
{
/* Is this a proxy for a mount namespace? */
- struct inode *inode = dentry->d_inode;
- return proc_ns_inode(inode) && dentry->d_fsdata == &mntns_operations;
+ return dentry->d_op == &ns_dentry_operations &&
+ dentry->d_fsdata == &mntns_operations;
}
struct mnt_namespace *to_mnt_ns(struct ns_common *ns)
@@ -2016,7 +2016,10 @@ static int do_loopback(struct path *path, const char *old_name,
if (IS_MNT_UNBINDABLE(old))
goto out2;
- if (!check_mnt(parent) || !check_mnt(old))
+ if (!check_mnt(parent))
+ goto out2;
+
+ if (!check_mnt(old) && old_path.dentry->d_op != &ns_dentry_operations)
goto out2;
if (!recurse && has_locked_children(old, old_path.dentry))