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VFS: Clean up shared mount flag propagation 

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 <viro@zeniv.linux.org.uk>
This commit is contained in:
Valerie Aurora 2010-01-26 14:20:47 -05:00 committed by Al Viro
parent 2ecdc82ef0
commit 495d6c9c65
3 changed files with 12 additions and 3 deletions
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2
fs/namespace.c
View File

@ -1538,7 +1538,7 @@ static int do_remount(struct path *path, int flags, int mnt_flags,
err = do_remount_sb(sb, flags, data, 0);
if (!err) {
spin_lock(&vfsmount_lock);
mnt_flags |= path->mnt->mnt_flags & MNT_PNODE_MASK;
mnt_flags |= path->mnt->mnt_flags & MNT_PROPAGATION_MASK;
path->mnt->mnt_flags = mnt_flags;
spin_unlock(&vfsmount_lock);
}

2
fs/pnode.h
View File

@ -25,7 +25,7 @@
static inline void set_mnt_shared(struct vfsmount *mnt)
{
mnt->mnt_flags &= ~MNT_PNODE_MASK;
mnt->mnt_flags &= ~MNT_SHARED_MASK;
mnt->mnt_flags |= MNT_SHARED;
}

11
include/linux/mount.h
View File

@ -34,7 +34,16 @@ struct mnt_namespace;
#define MNT_SHARED 0x1000 /* if the vfsmount is a shared mount */
#define MNT_UNBINDABLE 0x2000 /* if the vfsmount is a unbindable mount */
#define MNT_PNODE_MASK 0x3000 /* propagation flag mask */
/*
* MNT_SHARED_MASK is the set of flags that should be cleared when a
* mount becomes shared. Currently, this is only the flag that says a
* mount cannot be bind mounted, since this is how we create a mount
* that shares events with another mount. If you add a new MNT_*
* flag, consider how it interacts with shared mounts.
*/
#define MNT_SHARED_MASK (MNT_UNBINDABLE)
#define MNT_PROPAGATION_MASK (MNT_SHARED | MNT_UNBINDABLE)
struct vfsmount {
struct list_head mnt_hash;