death to mnt_pinned

Rather than playing silly buggers with vfsmount refcounts, just have
acct_on() ask fs/namespace.c for internal clone of file->f_path.mnt
and replace it with said clone. Then att

death to mnt_pinned

Rather than playing silly buggers with vfsmount refcounts, just have
acct_on() ask fs/namespace.c for internal clone of file->f_path.mnt
and replace it with said clone. Then attach the pin to original
vfsmount. Voila - the clone will be alive until the file gets closed,
making sure that underlying superblock remains active, etc., and
we can drop the original vfsmount, so that it's not kept busy.
If the file lives until the final mntput of the original vfsmount,
we'll notice that there's an fs_pin (one in bsd_acct_struct that
holds that file) and mnt_pin_kill() will take it out. Since
->kill() is synchronous, we won't proceed past that point until
these files are closed (and private clones of our vfsmount are
gone), so we get the same ordering warranties we used to get.

mnt_pin()/mnt_unpin()/->mnt_pinned is gone now, and good riddance -
it never became usable outside of kernel/acct.c (and racy wrt
umount even there).

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

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acct: get rid of acct_list

Put these suckers on per-vfsmount and per-superblock lists instead.
Note: right now it's still acct_lock for everything, but that's
going to change.

Signed-off-by: Al Vir

acct: get rid of acct_list

Put these suckers on per-vfsmount and per-superblock lists instead.
Note: right now it's still acct_lock for everything, but that's
going to change.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

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reduce m_start() cost...

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

switch mnt_hash to hlist

fixes RCU bug - walking through hlist is safe in face of element moves,
since it's self-terminating. Cyclic lists are not - if we end up jumping
to another hash chain, we'l

switch mnt_hash to hlist

fixes RCU bug - walking through hlist is safe in face of element moves,
since it's self-terminating. Cyclic lists are not - if we end up jumping
to another hash chain, we'll loop infinitely without ever hitting the
original list head.

[fix for dumb braino folded]

Spotted by: Max Kellermann <mk@cm4all.com>
Cc: stable@vger.kernel.org
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

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resizable namespace.c hashes

* switch allocation to alloc_large_system_hash()
* make sizes overridable by boot parameters (mhash_entries=, mphash_entries=)
* switch mountpoint_hashtable from list_he

resizable namespace.c hashes

* switch allocation to alloc_large_system_hash()
* make sizes overridable by boot parameters (mhash_entries=, mphash_entries=)
* switch mountpoint_hashtable from list_head to hlist_head

Cc: stable@vger.kernel.org
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

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vfs: Is mounted should be testing mnt_ns for NULL or error.

A bug was introduced with the is_mounted helper function in
commit f7a99c5b7c8bd3d3f533c8b38274e33f3da9096e
Author: Al Viro <viro@zeniv.li

vfs: Is mounted should be testing mnt_ns for NULL or error.

A bug was introduced with the is_mounted helper function in
commit f7a99c5b7c8bd3d3f533c8b38274e33f3da9096e
Author: Al Viro <viro@zeniv.linux.org.uk>
Date: Sat Jun 9 00:59:08 2012 -0400

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>

The intent was to test if the real_mount(vfsmount)->mnt_ns was
NULL_OR_ERR but the code is actually testing real_mount(vfsmount)
and always returning true.

The result is d_absolute_path returning paths it should be hiding.

Cc: stable@vger.kernel.org
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

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RCU'd vfsmounts

* RCU-delayed freeing of vfsmounts
* vfsmount_lock replaced with a seqlock (mount_lock)
* sequence number from mount_lock is stored in nameidata->m_seq and
used when we exit RCU mode

RCU'd vfsmounts

* RCU-delayed freeing of vfsmounts
* vfsmount_lock replaced with a seqlock (mount_lock)
* sequence number from mount_lock is stored in nameidata->m_seq and
used when we exit RCU mode
* new vfsmount flag - MNT_SYNC_UMOUNT. Set by umount_tree() when its
caller knows that vfsmount will have no surviving references.
* synchronize_rcu() done between unlocking namespace_sem in namespace_unlock()
and doing pending mntput().
* new helper: legitimize_mnt(mnt, seq). Checks the mount_lock sequence
number against seq, then grabs reference to mnt. Then it rechecks mount_lock
again to close the race and either returns success or drops the reference it
has acquired. The subtle point is that in case of MNT_SYNC_UMOUNT we can
simply decrement the refcount and sod off - aforementioned synchronize_rcu()
makes sure that final mntput() won't come until we leave RCU mode. We need
that, since we don't want to end up with some lazy pathwalk racing with
umount() and stealing the final mntput() from it - caller of umount() may
expect it to return only once the fs is shut down and we don't want to break
that. In other cases (i.e. with MNT_SYNC_UMOUNT absent) we have to do
full-blown mntput() in case of mount_lock sequence number mismatch happening
just as we'd grabbed the reference, but in those cases we won't be stealing
the final mntput() from anything that would care.
* mntput_no_expire() doesn't lock anything on the fast path now. Incidentally,
SMP and UP cases are handled the same way - no ifdefs there.
* normal pathname resolution does *not* do any writes to mount_lock. It does,
of course, bump the refcounts of vfsmount and dentry in the very end, but that's
it.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

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split __lookup_mnt() in two functions

Instead of passing the direction as argument (and checking it on every
step through the hash chain), just have separate __lookup_mnt() and
__lookup_mnt_last().

split __lookup_mnt() in two functions

Instead of passing the direction as argument (and checking it on every
step through the hash chain), just have separate __lookup_mnt() and
__lookup_mnt_last(). And use the standard iterators...

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

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new helpers: lock_mount_hash/unlock_mount_hash

aka br_write_{lock,unlock} of vfsmount_lock. Inlines in fs/mount.h,
vfsmount_lock extern moved over there as well.

Signed-off-by: Al Viro <viro@zeniv

new helpers: lock_mount_hash/unlock_mount_hash

aka br_write_{lock,unlock} of vfsmount_lock. Inlines in fs/mount.h,
vfsmount_lock extern moved over there as well.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

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namespace.c: get rid of mnt_ghosts

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

get rid of full-hash scan on detaching vfsmounts

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

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 nam

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>

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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-

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>

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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 n

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>

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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 contain

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>

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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

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>

show more ...

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: Tosh

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>

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switch mnt_namespace ->root to struct mount

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

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.

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>

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vfs: move fsnotify junk to struct mount

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

vfs: move mnt_devname

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

vfs: move mnt_list to struct mount

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

vfs: move the rest of int fields to struct mount

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

vfs: mnt_id/mnt_group_id moved

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

vfs: mnt_ns moved to struct mount

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>