path: root/fs/pnode.h
AgeCommit message (Collapse)Author
2015-04-09mnt: Honor MNT_LOCKED when detaching mountsEric W. Biederman
Modify umount(MNT_DETACH) to keep mounts in the hash table that are locked to their parent mounts, when the parent is lazily unmounted. In mntput_no_expire detach the children from the hash table, depending on mnt_pin_kill in cleanup_mnt to decrement the mnt_count of the children. In __detach_mounts if there are any mounts that have been unmounted but still are on the list of mounts of a mountpoint, remove their children from the mount hash table and those children to the unmounted list so they won't linger potentially indefinitely waiting for their final mntput, now that the mounts serve no purpose. Cc: Signed-off-by: "Eric W. Biederman" <>
2015-04-02mnt: Don't propagate unmounts to locked mountsEric W. Biederman
If the first mount in shared subtree is locked don't unmount the shared subtree. This is ensured by walking through the mounts parents before children and marking a mount as unmountable if it is not locked or it is locked but it's parent is marked. This allows recursive mount detach to propagate through a set of mounts when unmounting them would not reveal what is under any locked mount. Cc: Signed-off-by: "Eric W. Biederman" <>
2015-04-02mnt: On an unmount propagate clearing of MNT_LOCKEDEric W. Biederman
A prerequisite of calling umount_tree is that the point where the tree is mounted at is valid to unmount. If we are propagating the effect of the unmount clear MNT_LOCKED in every instance where the same filesystem is mounted on the same mountpoint in the mount tree, as we know (by virtue of the fact that umount_tree was called) that it is safe to reveal what is at that mountpoint. Cc: Signed-off-by: "Eric W. Biederman" <>
2015-04-02mnt: In umount_tree reuse mnt_list instead of mnt_hashEric W. Biederman
umount_tree builds a list of mounts that need to be unmounted. Utilize mnt_list for this purpose instead of mnt_hash. This begins to allow keeping a mount on the mnt_hash after it is unmounted, which is necessary for a properly functioning MNT_LOCKED implementation. The fact that mnt_list is an ordinary list makding available list_move is nice bonus. Cc: Signed-off-by: "Eric W. Biederman" <>
2015-04-02mnt: Improve the umount_tree flagsEric W. Biederman
- Remove the unneeded declaration from pnode.h - Mark umount_tree static as it has no callers outside of namespace.c - Define an enumeration of umount_tree's flags. - Pass umount_tree's flags in by name This removes the magic numbers 0, 1 and 2 making the code a little clearer and makes it possible for there to be lazy unmounts that don't propagate. Which is what __detach_mounts actually wants for example. Cc: Signed-off-by: "Eric W. Biederman" <>
2014-04-01smarter propagate_mnt()Al Viro
The current mainline has copies propagated to *all* nodes, then tears down the copies we made for nodes that do not contain counterparts of the desired mountpoint. That sets the right propagation graph for the copies (at teardown time we move the slaves of removed node to a surviving peer or directly to master), but we end up paying a fairly steep price in useless allocations. It's fairly easy to create a situation where N calls of mount(2) create exactly N bindings, with O(N^2) vfsmounts allocated and freed in process. Fortunately, it is possible to avoid those allocations/freeings. The trick is to create copies in the right order and find which one would've eventually become a master with the current algorithm. It turns out to be possible in O(nodes getting propagation) time and with no extra allocations at all. One part is that we need to make sure that eventual master will be created before its slaves, so we need to walk the propagation tree in a different order - by peer groups. And iterate through the peers before dealing with the next group. Another thing is finding the (earlier) copy that will be a master of one we are about to create; to do that we are (temporary) marking the masters of mountpoints we are attaching the copies to. Either we are in a peer of the last mountpoint we'd dealt with, or we have the following situation: we are attaching to mountpoint M, the last copy S_0 had been attached to M_0 and there are sequences S_0...S_n, M_0...M_n such that S_{i+1} is a master of S_{i}, S_{i} mounted on M{i} and we need to create a slave of the first S_{k} such that M is getting propagation from M_{k}. It means that the master of M_{k} will be among the sequence of masters of M. On the other hand, the nearest marked node in that sequence will either be the master of M_{k} or the master of M_{k-1} (the latter - in the case if M_{k-1} is a slave of something M gets propagation from, but in a wrong peer group). So we go through the sequence of masters of M until we find a marked one (P). Let N be the one before it. Then we go through the sequence of masters of S_0 until we find one (say, S) mounted on a node D that has P as master and check if D is a peer of N. If it is, S will be the master of new copy, if not - the master of S will be. That's it for the hard part; the rest is fairly simple. Iterator is in next_group(), handling of one prospective mountpoint is propagate_one(). It seems to survive all tests and gives a noticably better performance than the current mainline for setups that are seriously using shared subtrees. Cc: Signed-off-by: Al Viro <>
2014-03-30switch mnt_hash to hlistAl Viro
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 <> Cc: Signed-off-by: Al Viro <>
2013-08-26vfs: Don't copy mount bind mounts of /proc/<pid>/ns/mnt between namespacesEric W. Biederman
Don't copy bind mounts of /proc/<pid>/ns/mnt between namespaces. These files hold references to a mount namespace and copying them between namespaces could result in a reference counting loop. The current mnt_ns_loop test prevents loops on the assumption that mounts don't cross between namespaces. Unfortunately unsharing a mount namespace and shared substrees can both cause mounts to propogate between mount namespaces. Add two flags CL_COPY_UNBINDABLE and CL_COPY_MNT_NS_FILE are added to control this behavior, and CL_COPY_ALL is redefined as both of them. Signed-off-by: "Eric W. Biederman" <>
2013-05-01Merge branch 'for-linus' of ↵Linus Torvalds
git:// Pull VFS updates from Al Viro, Misc cleanups all over the place, mainly wrt /proc interfaces (switch create_proc_entry to proc_create(), get rid of the deprecated create_proc_read_entry() in favor of using proc_create_data() and seq_file etc). 7kloc removed. * 'for-linus' of git:// (204 commits) don't bother with deferred freeing of fdtables proc: Move non-public stuff from linux/proc_fs.h to fs/proc/internal.h proc: Make the PROC_I() and PDE() macros internal to procfs proc: Supply a function to remove a proc entry by PDE take cgroup_open() and cpuset_open() to fs/proc/base.c ppc: Clean up scanlog ppc: Clean up rtas_flash driver somewhat hostap: proc: Use remove_proc_subtree() drm: proc: Use remove_proc_subtree() drm: proc: Use minor->index to label things, not PDE->name drm: Constify drm_proc_list[] zoran: Don't print proc_dir_entry data in debug reiserfs: Don't access the proc_dir_entry in r_open(), r_start() r_show() proc: Supply an accessor for getting the data from a PDE's parent airo: Use remove_proc_subtree() rtl8192u: Don't need to save device proc dir PDE rtl8187se: Use a dir under /proc/net/r8180/ proc: Add proc_mkdir_data() proc: Move some bits from linux/proc_fs.h to linux/{of.h,signal.h,tty.h} proc: Move PDE_NET() to fs/proc/proc_net.c ...
2013-04-09switch unlock_mount() to namespace_unlock(), convert all umount_tree() callersAl Viro
which allows to kill the last argument of umount_tree() and make release_mounts() static. Signed-off-by: Al Viro <>
2013-04-09get rid of full-hash scan on detaching vfsmountsAl Viro
Signed-off-by: Al Viro <>
2013-03-27vfs: Carefully propogate mounts across user namespacesEric W. Biederman
As a matter of policy MNT_READONLY should not be changable if the original mounter had more privileges than creator of the mount namespace. Add the flag CL_UNPRIVILEGED to note when we are copying a mount from a mount namespace that requires more privileges to a mount namespace that requires fewer privileges. When the CL_UNPRIVILEGED flag is set cause clone_mnt to set MNT_NO_REMOUNT if any of the mnt flags that should never be changed are set. This protects both mount propagation and the initial creation of a less privileged mount namespace. Cc: Acked-by: Serge Hallyn <> Reported-by: Andy Lutomirski <> Signed-off-by: "Eric W. Biederman" <>
2012-11-19vfs: Only support slave subtrees across different user namespacesEric W. Biederman
Sharing mount subtress with mount namespaces created by unprivileged users allows unprivileged mounts created by unprivileged users to propagate to mount namespaces controlled by privileged users. Prevent nasty consequences by changing shared subtrees to slave subtress when an unprivileged users creates a new mount namespace. Acked-by: Serge Hallyn <> Signed-off-by: "Eric W. Biederman" <>
2012-01-03vfs: switch pnode.h macros to struct mount *Al Viro
Signed-off-by: Al Viro <>
2012-01-03vfs: spread struct mount - remaining argument of mnt_set_mountpoint()Al Viro
Signed-off-by: Al Viro <>
2012-01-03vfs: spread struct mount - propagate_mnt()Al Viro
Signed-off-by: Al Viro <>
2012-01-03vfs: spread struct mount - get_dominating_id / do_make_slaveAl Viro
next pile of horrors, similar to mnt_parent one; this time it's mnt_master. Signed-off-by: Al Viro <>
2012-01-03vfs: spread struct mount - work with countersAl Viro
Signed-off-by: Al Viro <>
2012-01-03vfs: spread struct mount - is_path_reachableAl Viro
Signed-off-by: Al Viro <>
2012-01-03vfs: spread struct mount - do_umount/propagate_mount_busyAl Viro
Signed-off-by: Al Viro <>
2012-01-03vfs: spread struct mount mnt_set_mountpoint child argumentAl Viro
Signed-off-by: Al Viro <>
2012-01-03vfs: spread struct mount - clone_mnt/copy_tree argumentAl Viro
Signed-off-by: Al Viro <>
2012-01-03vfs: spread struct mount - umount_tree argumentAl Viro
Signed-off-by: Al Viro <>
2012-01-03vfs: spread struct mount - clone_mnt/copy_tree resultAl Viro
Signed-off-by: Al Viro <>
2012-01-03vfs: spread struct mount - change_mnt_propagation/set_mnt_sharedAl Viro
Signed-off-by: Al Viro <>
2012-01-03vfs: spread struct mount - mount group id handlingAl Viro
Signed-off-by: Al Viro <>
2012-01-03vfs: add missing parens in pnode.h macrosAl Viro
Signed-off-by: Al Viro <>
2012-01-03vfs: more mnt_parent cleanupsAl Viro
a) mount --move is checking that ->mnt_parent is non-NULL before looking if that parent happens to be shared; ->mnt_parent is never NULL and it's not even an misspelled !mnt_has_parent() b) pivot_root open-codes is_path_reachable(), poorly. c) so does path_is_under(), while we are at it. Signed-off-by: Al Viro <>
2012-01-03vfs: new internal helper: mnt_has_parent(mnt)Al Viro
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 <>
2012-01-03trim fs/internal.hAl Viro
some stuff in there can actually become static; some belongs to pnode.h as it's a private interface between namespace.c and pnode.c... Signed-off-by: Al Viro <>
2010-03-03VFS: Clean up shared mount flag propagationValerie Aurora
The handling of mount flags in set_mnt_shared() got a little tangled up during previous cleanups, with the following problems: * MNT_PNODE_MASK is defined as a literal constant when it should be a bitwise xor of other MNT_* flags * set_mnt_shared() clears and then sets MNT_SHARED (part of MNT_PNODE_MASK) * MNT_PNODE_MASK could use a comment in mount.h * MNT_PNODE_MASK is a terrible name, change to MNT_SHARED_MASK This patch fixes these problems. Signed-off-by: Al Viro <>
2010-03-03Kill CL_PROPAGATION, sanitize fs/pnode.c:get_source()Al Viro
First of all, get_source() never results in CL_PROPAGATION alone. We either get CL_MAKE_SHARED (for the continuation of peer group) or CL_SLAVE (slave that is not shared) or both (beginning of peer group among slaves). Massage the code to make that explicit, kill CL_PROPAGATION test in clone_mnt() (nothing sets CL_MAKE_SHARED without CL_PROPAGATION and in clone_mnt() we are checking CL_PROPAGATION after we'd found that there's no CL_SLAVE, so the check for CL_MAKE_SHARED would do just as well). Fix comments, while we are at it... Signed-off-by: Al Viro <>
2008-04-23[patch 7/7] vfs: mountinfo: show dominating group idMiklos Szeredi
Show peer group ID of nearest dominating group that has intersection with the mount's namespace. Signed-off-by: Miklos Szeredi <> Signed-off-by: Al Viro <>
2008-04-21[PATCH] teach seq_file to discard entriesAl Viro
Allow ->show() return SEQ_SKIP; that will discard all output from that element and move on. Signed-off-by: Al Viro <>
2007-10-21[PATCH] new helpers - collect_mounts() and release_collected_mounts()Al Viro
Get a snapshot of a subtree, creating private clones of vfsmounts for all its components and release such snapshot resp. Signed-off-by: Al Viro <>
2006-12-08[PATCH] rename struct namespace to struct mnt_namespaceKirill Korotaev
Rename 'struct namespace' to 'struct mnt_namespace' to avoid confusion with other namespaces being developped for the containers : pid, uts, ipc, etc. 'namespace' variables and attributes are also renamed to 'mnt_ns' Signed-off-by: Kirill Korotaev <> Signed-off-by: Cedric Le Goater <> Cc: Eric W. Biederman <> Cc: Herbert Poetzl <> Cc: Sukadev Bhattiprolu <> Signed-off-by: Andrew Morton <> Signed-off-by: Linus Torvalds <>
2005-11-07[PATCH] unbindable mountsRam Pai
An unbindable mount does not forward or receive propagation. Also unbindable mount disallows bind mounts. The semantics is as follows. Bind semantics: It is invalid to bind mount an unbindable mount. Move semantics: It is invalid to move an unbindable mount under shared mount. Clone-namespace semantics: If a mount is unbindable in the parent namespace, the corresponding cloned mount in the child namespace becomes unbindable too. Note: there is subtle difference, unbindable mounts cannot be bind mounted but can be cloned during clone-namespace. Signed-off-by: Ram Pai <> Signed-off-by: Al Viro <> Signed-off-by: Linus Torvalds <>
2005-11-07[PATCH] introduce slave mountsRam Pai
A slave mount always has a master mount from which it receives mount/umount events. Unlike shared mount the event propagation does not flow from the slave mount to the master. Signed-off-by: Ram Pai <> Signed-off-by: Al Viro <> Signed-off-by: Linus Torvalds <>
2005-11-07[PATCH] shared mounts handling: umountRam Pai
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 <> Signed-off-by: Al Viro <> Signed-off-by: Linus Torvalds <>
2005-11-07[PATCH] shared mount handling: bind and rbindRam Pai
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 <> Signed-off-by: Al Viro <> Signed-off-by: Linus Torvalds <>
2005-11-07[PATCH] introduce shared mountsRam Pai
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 <> Signed-off-by: Al Viro <> Signed-off-by: Linus Torvalds <>
2005-11-07[PATCH] beginning of the shared-subtree properRam Pai
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 <> Signed-off-by: Al Viro <> Signed-off-by: Linus Torvalds <>