An unmount of a mount creates a umount event on the parent. If the
parent is a shared mount, it gets propagated to all mounts in the peer
group.
Signed-off-by: Ram Pai <linuxram@us.ibm.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Implement handling of mount --move in presense of shared mounts (see
Documentation/sharedsubtree.txt in the end of patch series for detailed
description).
Signed-off-by: Ram Pai <linuxram@us.ibm.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Implement handling of MS_BIND in presense of shared mounts (see
Documentation/sharedsubtree.txt in the end of patch series for detailed
description).
Signed-off-by: Ram Pai <linuxram@us.ibm.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This creates shared mounts. A shared mount when bind-mounted to some
mountpoint, propagates mount/umount events to each other. All the
shared mounts that propagate events to each other belong to the same
peer-group.
Signed-off-by: Ram Pai <linuxram@us.ibm.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
A private mount does not forward or receive propagation. This patch
provides user the ability to convert any mount to private.
Signed-off-by: Ram Pai <linuxram@us.ibm.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This removes the per-namespace semaphore in favor of a global semaphore.
This can have an effect on namespace scalability.
Signed-off-by: Miklos Szeredi <miklos@szeredi.hu>
Signed-off-by: Ram Pai <linuxram@us.ibm.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
- clean up the ugliness in may_umount_tree()
- fix a bug in do_loopback(). after cloning a tree, do_loopback()
unlinks only the topmost mount of the cloned tree, leaving behind the
children mounts on their corresponding expiry list.
Signed-off-by: Ram Pai <linuxram@us.ibm.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
umount is done under the protection of the namespace semaphore. This
can lead to intresting deadlocks when the last reference to a mount is
released, if filesystem code is in sufficiently nasty state.
This collects all the to-be-released-mounts and releases them after
releasing the namespace semaphore. That both reduces the time we are
holding namespace semaphore and gets the things more robust.
Idea proposed by Al Viro.
Signed-off-by: Ram Pai <linuxram@us.ibm.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Old semantics: graft_tree() grabs a reference on the vfsmount before
returning success.
New one: graft_tree() leaves that to caller.
All the callers of graft_tree() immediately dropped that reference
anyway. Changing the interface takes care of this unnecessary overhead.
Idea proposed by Al Viro.
Signed-off-by: Ram Pai <linuxram@us.ibm.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Allow caller of seq_open() to kmalloc() seq_file + whatever else they
want and set ->private_data to it. seq_open() will then abstain from
doing allocation itself.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
- check_mnt() on the source of binding should've been unconditional
from the very beginning. My fault - as far I could've trace it,
that's an old thinko made back in 2001. Kudos to Miklos for spotting
it...
Fixed.
- code cleaned up.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
The way we currently deal with quota and process accounting that might
keep vfsmount busy at umount time is inherently broken; we try to turn
them off just in case (not quite correctly, at that) and
a) pray umount doesn't fail (otherwise they'll stay turned off)
b) pray nobody doesn anything funny just as we turn quota off
Moreover, LSM provides hooks for doing the same sort of broken logics.
The proper way to deal with that is to introduce the second kind of
reference to vfsmount. Semantics:
- when the last normal reference is dropped, all special ones are
converted to normal ones and if there had been any, cleanup is done.
- normal reference can be cloned into a special one
- special reference can be converted to normal one; that's a no-op if
we'd already passed the point of no return (i.e. mntput() had
converted special references to normal and started cleanup).
The way it works: e.g. starting process accounting converts the vfsmount
reference pinned by the opened file into special one and turns it back
to normal when it gets shut down; acct_auto_close() is done when no
normal references are left. That way it does *not* obstruct umount(2)
and it silently gets turned off when the last normal reference to
vfsmount is gone. Which is exactly what we want...
The same should be done by LSM module that holds some internal
references to vfsmount and wants to shut them down on umount - it should
make them special and security_sb_umount_close() will be called exactly
when the last normal reference to vfsmount is gone.
quota handling is even simpler - we don't use normal file IO anymore, so
there's no need to hold vfsmounts at all. DQUOT_OFF() is done from
deactivate_super(), where it really belongs.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Patch from Uli Luckas
This is a simplification of patch 3116/1 as sugested by Russell King.
Signed-off-by: Uli Luckas <u.luckas@road-gmbh.de>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Patch from Lennert Buytenhek
Since we have to use XCB=101 instead of XCB=000 on the ixp2400 to
prevent it from regularly falling over, and since we have to deal with
manual write buffer flushing because of that, we might as well use
XCB=101 on all ixp2000 platforms since it's faster than XCB=000.
Signed-off-by: Lennert Buytenhek <buytenh@wantstofly.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Patch from Lennert Buytenhek
nwfpe extended precision emulation used to be broken on big-endian
and was therefore disabled. This patch fixes nwfpe so that it copies
extended precision floats to/from userspace in the proper word order
(similar to patch #2046, see the description of that patch for an
explanation) and reenables the Kconfig option.
Signed-off-by: Lennert Buytenhek <buytenh@wantstofly.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Patch from Lennert Buytenhek
The routine that nwfpe uses for converting floats/doubles to
extended precision fails to zero two bytes of kernel stack. This
is not immediately obvious, as the floatx80 structure has 16 bits
of implicit padding (by design.) These two bytes are copied to
userspace when an stfe is emulated, causing a possible info leak.
Make the padding explicit and zero it out in the relevant places.
Signed-off-by: Lennert Buytenhek <buytenh@wantstofly.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Ram Pai
Al Viro
Linus Torvalds
Russell King
Uli Luckas
Lennert Buytenhek