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mnt: Improve the umount_tree flags 

- 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: stable@vger.kernel.org
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
This commit is contained in:
Eric W. Biederman 2014-12-24 07:20:01 -06:00
parent a3b3c5627c
commit e819f15210
2 changed files with 16 additions and 16 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

31
fs/namespace.c
View File

@ -1317,14 +1317,15 @@ static inline void namespace_lock(void)
down_write(&namespace_sem);
}
enum umount_tree_flags {
UMOUNT_SYNC = 1,
UMOUNT_PROPAGATE = 2,
};
/*
* mount_lock must be held
* namespace_sem must be held for write
* how = 0 => just this tree, don't propagate
* how = 1 => propagate; we know that nobody else has reference to any victims
* how = 2 => lazy umount
*/
void umount_tree(struct mount *mnt, int how)
static void umount_tree(struct mount *mnt, enum umount_tree_flags how)
{
HLIST_HEAD(tmp_list);
struct mount *p;
@ -1337,7 +1338,7 @@ void umount_tree(struct mount *mnt, int how)
hlist_for_each_entry(p, &tmp_list, mnt_hash)
list_del_init(&p->mnt_child);
if (how)
if (how & UMOUNT_PROPAGATE)
propagate_umount(&tmp_list);
while (!hlist_empty(&tmp_list)) {
@ -1347,7 +1348,7 @@ void umount_tree(struct mount *mnt, int how)
list_del_init(&p->mnt_list);
__touch_mnt_namespace(p->mnt_ns);
p->mnt_ns = NULL;
if (how < 2)
if (how & UMOUNT_SYNC)
p->mnt.mnt_flags |= MNT_SYNC_UMOUNT;
pin_insert_group(&p->mnt_umount, &p->mnt_parent->mnt, &unmounted);
@ -1445,14 +1446,14 @@ static int do_umount(struct mount *mnt, int flags)
if (flags & MNT_DETACH) {
if (!list_empty(&mnt->mnt_list))
umount_tree(mnt, 2);
umount_tree(mnt, UMOUNT_PROPAGATE);
retval = 0;
} else {
shrink_submounts(mnt);
retval = -EBUSY;
if (!propagate_mount_busy(mnt, 2)) {
if (!list_empty(&mnt->mnt_list))
umount_tree(mnt, 1);
umount_tree(mnt, UMOUNT_PROPAGATE|UMOUNT_SYNC);
retval = 0;
}
}
@ -1484,7 +1485,7 @@ void __detach_mounts(struct dentry *dentry)
lock_mount_hash();
while (!hlist_empty(&mp->m_list)) {
mnt = hlist_entry(mp->m_list.first, struct mount, mnt_mp_list);
umount_tree(mnt, 2);
umount_tree(mnt, UMOUNT_PROPAGATE);
}
unlock_mount_hash();
put_mountpoint(mp);
@ -1646,7 +1647,7 @@ struct mount *copy_tree(struct mount *mnt, struct dentry *dentry,
out:
if (res) {
lock_mount_hash();
umount_tree(res, 0);
umount_tree(res, UMOUNT_SYNC);
unlock_mount_hash();
}
return q;
@ -1670,7 +1671,7 @@ void drop_collected_mounts(struct vfsmount *mnt)
{
namespace_lock();
lock_mount_hash();
umount_tree(real_mount(mnt), 0);
umount_tree(real_mount(mnt), UMOUNT_SYNC);
unlock_mount_hash();
namespace_unlock();
}
@ -1853,7 +1854,7 @@ static int attach_recursive_mnt(struct mount *source_mnt,
out_cleanup_ids:
while (!hlist_empty(&tree_list)) {
child = hlist_entry(tree_list.first, struct mount, mnt_hash);
umount_tree(child, 0);
umount_tree(child, UMOUNT_SYNC);
}
unlock_mount_hash();
cleanup_group_ids(source_mnt, NULL);
@ -2033,7 +2034,7 @@ static int do_loopback(struct path *path, const char *old_name,
err = graft_tree(mnt, parent, mp);
if (err) {
lock_mount_hash();
umount_tree(mnt, 0);
umount_tree(mnt, UMOUNT_SYNC);
unlock_mount_hash();
}
out2:
@ -2404,7 +2405,7 @@ void mark_mounts_for_expiry(struct list_head *mounts)
while (!list_empty(&graveyard)) {
mnt = list_first_entry(&graveyard, struct mount, mnt_expire);
touch_mnt_namespace(mnt->mnt_ns);
umount_tree(mnt, 1);
umount_tree(mnt, UMOUNT_PROPAGATE|UMOUNT_SYNC);
}
unlock_mount_hash();
namespace_unlock();
@ -2475,7 +2476,7 @@ static void shrink_submounts(struct mount *mnt)
m = list_first_entry(&graveyard, struct mount,
mnt_expire);
touch_mnt_namespace(m->mnt_ns);
umount_tree(m, 1);
umount_tree(m, UMOUNT_PROPAGATE|UMOUNT_SYNC);
}
}
}

1
fs/pnode.h
View File

@ -47,7 +47,6 @@ int get_dominating_id(struct mount *mnt, const struct path *root);
unsigned int mnt_get_count(struct mount *mnt);
void mnt_set_mountpoint(struct mount *, struct mountpoint *,
struct mount *);
void umount_tree(struct mount *, int);
struct mount *copy_tree(struct mount *, struct dentry *, int);
bool is_path_reachable(struct mount *, struct dentry *,
const struct path *root);