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[PATCH] new helpers - collect_mounts() and release_collected_mounts()

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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 <viro@zeniv.linux.org.uk>
This commit is contained in:
Al Viro 2007-06-07 12:20:32 -04:00
parent 5a190ae697
commit 8aec080945
3 changed files with 24 additions and 1 deletions
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22
fs/namespace.c
View File

@ -246,7 +246,7 @@ static struct vfsmount *clone_mnt(struct vfsmount *old, struct dentry *root,
list_add(&mnt->mnt_slave, &old->mnt_slave_list);
mnt->mnt_master = old;
CLEAR_MNT_SHARED(mnt);
} else {
} else if (!(flag & CL_PRIVATE)) {
if ((flag & CL_PROPAGATION) || IS_MNT_SHARED(old))
list_add(&mnt->mnt_share, &old->mnt_share);
if (IS_MNT_SLAVE(old))
@ -746,6 +746,26 @@ Enomem:
return NULL;
}
struct vfsmount *collect_mounts(struct vfsmount *mnt, struct dentry *dentry)
{
struct vfsmount *tree;
down_read(&namespace_sem);
tree = copy_tree(mnt, dentry, CL_COPY_ALL | CL_PRIVATE);
up_read(&namespace_sem);
return tree;
}
void drop_collected_mounts(struct vfsmount *mnt)
{
LIST_HEAD(umount_list);
down_read(&namespace_sem);
spin_lock(&vfsmount_lock);
umount_tree(mnt, 0, &umount_list);
spin_unlock(&vfsmount_lock);
up_read(&namespace_sem);
release_mounts(&umount_list);
}
/*
* @source_mnt : mount tree to be attached
* @nd : place the mount tree @source_mnt is attached

1
fs/pnode.h
View File

@ -22,6 +22,7 @@
#define CL_COPY_ALL 0x04
#define CL_MAKE_SHARED 0x08
#define CL_PROPAGATION 0x10
#define CL_PRIVATE 0x20
static inline void set_mnt_shared(struct vfsmount *mnt)
{

2
include/linux/fs.h
View File

@ -1470,6 +1470,8 @@ extern long do_mount(char *, char *, char *, unsigned long, void *);
extern struct vfsmount *copy_tree(struct vfsmount *, struct dentry *, int);
extern void mnt_set_mountpoint(struct vfsmount *, struct dentry *,
struct vfsmount *);
extern struct vfsmount *collect_mounts(struct vfsmount *, struct dentry *);
extern void drop_collected_mounts(struct vfsmount *);
extern int vfs_statfs(struct dentry *, struct kstatfs *);