[PATCH 3.13 17/22] keep shadowed vfsmounts together

From: Greg Kroah-Hartman
Date: Tue Apr 01 2014 - 00:16:32 EST


3.13-stable review patch. If anyone has any objections, please let me know.

------------------

From: Al Viro <viro@xxxxxxxxxxxxxxxxxx>

commit 1d6a32acd70ab18499829c0a9a5dbe2bace72a13 upstream.

preparation to switching mnt_hash to hlist

Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
fs/namespace.c | 32 +++++++++++++++++++++++---------
1 file changed, 23 insertions(+), 9 deletions(-)

--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -621,12 +621,20 @@ struct mount *__lookup_mnt(struct vfsmou
struct mount *__lookup_mnt_last(struct vfsmount *mnt, struct dentry *dentry)
{
struct list_head *head = m_hash(mnt, dentry);
- struct mount *p;
+ struct mount *p, *res = NULL;

- list_for_each_entry_reverse(p, head, mnt_hash)
+ list_for_each_entry(p, head, mnt_hash)
if (&p->mnt_parent->mnt == mnt && p->mnt_mountpoint == dentry)
- return p;
- return NULL;
+ goto found;
+ return res;
+found:
+ res = p;
+ list_for_each_entry_continue(p, head, mnt_hash) {
+ if (&p->mnt_parent->mnt != mnt || p->mnt_mountpoint != dentry)
+ break;
+ res = p;
+ }
+ return res;
}

/*
@@ -769,14 +777,14 @@ static void attach_mnt(struct mount *mnt
struct mountpoint *mp)
{
mnt_set_mountpoint(parent, mp, mnt);
- list_add_tail(&mnt->mnt_hash, m_hash(&parent->mnt, mp->m_dentry));
+ list_add(&mnt->mnt_hash, m_hash(&parent->mnt, mp->m_dentry));
list_add_tail(&mnt->mnt_child, &parent->mnt_mounts);
}

/*
* vfsmount lock must be held for write
*/
-static void commit_tree(struct mount *mnt)
+static void commit_tree(struct mount *mnt, struct mount *shadows)
{
struct mount *parent = mnt->mnt_parent;
struct mount *m;
@@ -791,7 +799,10 @@ static void commit_tree(struct mount *mn

list_splice(&head, n->list.prev);

- list_add_tail(&mnt->mnt_hash,
+ if (shadows)
+ list_add(&mnt->mnt_hash, &shadows->mnt_hash);
+ else
+ list_add(&mnt->mnt_hash,
m_hash(&parent->mnt, mnt->mnt_mountpoint));
list_add_tail(&mnt->mnt_child, &parent->mnt_mounts);
touch_mnt_namespace(n);
@@ -1659,12 +1670,15 @@ static int attach_recursive_mnt(struct m
touch_mnt_namespace(source_mnt->mnt_ns);
} else {
mnt_set_mountpoint(dest_mnt, dest_mp, source_mnt);
- commit_tree(source_mnt);
+ commit_tree(source_mnt, NULL);
}

list_for_each_entry_safe(child, p, &tree_list, mnt_hash) {
+ struct mount *q;
list_del_init(&child->mnt_hash);
- commit_tree(child);
+ q = __lookup_mnt_last(&child->mnt_parent->mnt,
+ child->mnt_mountpoint);
+ commit_tree(child, q);
}
unlock_mount_hash();



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