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| author | Al Viro <viro@zeniv.linux.org.uk> | 2014-11-01 10:57:28 -0400 |
|---|---|---|
| committer | Al Viro <viro@zeniv.linux.org.uk> | 2014-12-10 21:30:20 -0500 |
| commit | e149ed2b805fefdccf7ccdfc19eca22fdd4514ac (patch) | |
| tree | 8c9cd88deff8c7309ca2acb8d4cb475aaca47b14 /fs/namespace.c | |
| parent | f77c80142e1afe6d5c16975ca5d7d1fc324b16f9 (diff) | |
| download | lwn-e149ed2b805fefdccf7ccdfc19eca22fdd4514ac.tar.gz lwn-e149ed2b805fefdccf7ccdfc19eca22fdd4514ac.zip | |
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.c | 9 |
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)) |