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copy_mnt_ns(): use guards

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* mntput() of rootmnt and pwdmnt done via __free(mntput)
* mnt_ns_tree_add() can be done within namespace_excl scope.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Al Viro 2025-08-26 17:12:15 -04:00
parent 7bb4c851dc
commit d7b7253a0a
1 changed files with 4 additions and 12 deletions
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16
fs/namespace.c
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@ -4158,7 +4158,8 @@ struct mnt_namespace *copy_mnt_ns(unsigned long flags, struct mnt_namespace *ns,
struct user_namespace *user_ns, struct fs_struct *new_fs)
{
struct mnt_namespace *new_ns;
struct vfsmount *rootmnt = NULL, *pwdmnt = NULL;
struct vfsmount *rootmnt __free(mntput) = NULL;
struct vfsmount *pwdmnt __free(mntput) = NULL;
struct mount *p, *q;
struct mount *old;
struct mount *new;
@ -4177,7 +4178,7 @@ struct mnt_namespace *copy_mnt_ns(unsigned long flags, struct mnt_namespace *ns,
if (IS_ERR(new_ns))
return new_ns;
namespace_lock();
guard(namespace_excl)();
/* First pass: copy the tree topology */
copy_flags = CL_COPY_UNBINDABLE | CL_EXPIRE;
if (user_ns != ns->user_ns)
@ -4185,13 +4186,11 @@ struct mnt_namespace *copy_mnt_ns(unsigned long flags, struct mnt_namespace *ns,
new = copy_tree(old, old->mnt.mnt_root, copy_flags);
if (IS_ERR(new)) {
emptied_ns = new_ns;
namespace_unlock();
return ERR_CAST(new);
}
if (user_ns != ns->user_ns) {
lock_mount_hash();
guard(mount_writer)();
lock_mnt_tree(new);
unlock_mount_hash();
}
new_ns->root = new;
@ -4223,13 +4222,6 @@ struct mnt_namespace *copy_mnt_ns(unsigned long flags, struct mnt_namespace *ns,
while (p->mnt.mnt_root != q->mnt.mnt_root)
p = next_mnt(skip_mnt_tree(p), old);
}
namespace_unlock();
if (rootmnt)
mntput(rootmnt);
if (pwdmnt)
mntput(pwdmnt);
mnt_ns_tree_add(new_ns);
return new_ns;
}