Commit graph

27 commits

Author SHA1 Message Date
Eric W. Biederman
98f842e675 proc: Usable inode numbers for the namespace file descriptors.
Assign a unique proc inode to each namespace, and use that
inode number to ensure we only allocate at most one proc
inode for every namespace in proc.

A single proc inode per namespace allows userspace to test
to see if two processes are in the same namespace.

This has been a long requested feature and only blocked because
a naive implementation would put the id in a global space and
would ultimately require having a namespace for the names of
namespaces, making migration and certain virtualization tricks
impossible.

We still don't have per superblock inode numbers for proc, which
appears necessary for application unaware checkpoint/restart and
migrations (if the application is using namespace file descriptors)
but that is now allowd by the design if it becomes important.

I have preallocated the ipc and uts initial proc inode numbers so
their structures can be statically initialized.

Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
2012-11-20 04:19:49 -08:00
Eric W. Biederman
771b137168 vfs: Add a user namespace reference from struct mnt_namespace
This will allow for support for unprivileged mounts in a new user namespace.

Acked-by: "Serge E. Hallyn" <serge@hallyn.com>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2012-11-19 05:59:19 -08:00
Eric W. Biederman
8823c079ba 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>
2012-11-19 05:59:18 -08:00
Al Viro
6ce6e24e72 get rid of magic in proc_namespace.c
don't rely on proc_mounts->m being the first field; container_of()
is there for purpose.  No need to bother with ->private, while
we are at it - the same container_of will do nicely.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-07-14 16:32:48 +04:00
Al Viro
f7a99c5b7c get rid of ->mnt_longterm
it's enough to set ->mnt_ns of internal vfsmounts to something
distinct from all struct mnt_namespace out there; then we can
just use the check for ->mnt_ns != NULL in the fast path of
mntput_no_expire()

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-07-14 16:32:47 +04:00
Miklos Szeredi
39f7c4db1d vfs: keep list of mounts for each superblock
Keep track of vfsmounts belonging to a superblock.  List is protected
by vfsmount_lock.

Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Tested-by: Toshiyuki Okajima <toshi.okajima@jp.fujitsu.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-01-06 23:20:12 -05:00
Al Viro
be08d6d260 switch mnt_namespace ->root to struct mount
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-01-03 22:57:13 -05:00
Al Viro
0226f4923f vfs: take /proc/*/mounts and friends to fs/proc_namespace.c
rationale: that stuff is far tighter bound to fs/namespace.c than to
the guts of procfs proper.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-01-03 22:57:13 -05:00
Al Viro
c63181e6b6 vfs: move fsnotify junk to struct mount
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-01-03 22:57:12 -05:00
Al Viro
52ba1621de vfs: move mnt_devname
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-01-03 22:57:11 -05:00
Al Viro
1a4eeaf2a8 vfs: move mnt_list to struct mount
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-01-03 22:57:11 -05:00
Al Viro
863d684f94 vfs: move the rest of int fields to struct mount
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-01-03 22:57:10 -05:00
Al Viro
15169fe784 vfs: mnt_id/mnt_group_id moved
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-01-03 22:57:10 -05:00
Al Viro
143c8c91ce vfs: mnt_ns moved to struct mount
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-01-03 22:57:09 -05:00
Al Viro
6776db3d32 vfs: take mnt_share/mnt_slave/mnt_slave_list and mnt_expire to struct mount
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-01-03 22:57:08 -05:00
Al Viro
32301920f4 vfs: and now we can make ->mnt_master point to struct mount
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-01-03 22:57:08 -05:00
Al Viro
d10e8def07 vfs: take mnt_master to struct mount
make IS_MNT_SLAVE take struct mount * at the same time

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-01-03 22:57:08 -05:00
Al Viro
6b41d536f7 vfs: take mnt_child/mnt_mounts to struct mount
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-01-03 22:57:06 -05:00
Al Viro
68e8a9feab vfs: all counters taken to struct mount
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-01-03 22:57:06 -05:00
Al Viro
a73324da7a vfs: move mnt_mountpoint to struct mount
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-01-03 22:57:05 -05:00
Al Viro
0714a53380 vfs: now it can be done - make mnt_parent point to struct mount
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-01-03 22:57:05 -05:00
Al Viro
3376f34fff vfs: mnt_parent moved to struct mount
the second victim...

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-01-03 22:57:04 -05:00
Al Viro
676da58df7 vfs: spread struct mount - mnt_has_parent
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-01-03 22:57:04 -05:00
Al Viro
1b8e5564b9 vfs: the first spoils - mnt_hash moved
taken out of struct vfsmount into struct mount

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-01-03 22:57:02 -05:00
Al Viro
c71053659e vfs: spread struct mount - __lookup_mnt() result
switch __lookup_mnt() to returning struct mount *; callers adjusted.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-01-03 22:56:58 -05:00
Al Viro
7d6fec45a5 vfs: start hiding vfsmount guts series
Almost all fields of struct vfsmount are used only by core VFS (and
a fairly small part of it, at that).  The plan: embed struct vfsmount
into struct mount, making the latter visible only to core parts of VFS.
Then move fields from vfsmount to mount, eventually leaving only
mnt_root/mnt_sb/mnt_flags in struct vfsmount.  Filesystem code still
gets pointers to struct vfsmount and remains unchanged; all such
pointers go to struct vfsmount embedded into the instances of struct
mount allocated by fs/namespace.c.  When fs/namespace.c et.al. get
a pointer to vfsmount, they turn it into pointer to mount (using
container_of) and work with that.

This is the first part of series; struct mount is introduced,
allocation switched to using it.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-01-03 22:56:57 -05:00
Al Viro
b2dba1af3c vfs: new internal helper: mnt_has_parent(mnt)
vfsmounts have ->mnt_parent pointing either to a different vfsmount
or to itself; it's never NULL and termination condition in loops
traversing the tree towards root is mnt == mnt->mnt_parent.  At least
one place (see the next patch) is confused about what's going on;
let's add an explicit helper checking it right way and use it in
all places where we need it.  Not that there had been too many,
but...

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-01-03 22:52:36 -05:00