On Fri, 2021-12-10 at 12:49 +0100, Christian Brauner wrote:
On Thu, Dec 09, 2021 at 02:38:13PM -0500, James Bottomley wrote:
[...]
quoted
@@ -317,21 +315,15 @@ EXPORT_SYMBOL_GPL(securityfs_create_symlink);
void securityfs_remove(struct dentry *dentry)
{
struct user_namespace *ns = dentry->d_sb->s_user_ns;
- struct inode *dir;
if (!dentry || IS_ERR(dentry))
return;
- dir = d_inode(dentry->d_parent);
- inode_lock(dir);
if (simple_positive(dentry)) {
- if (d_is_dir(dentry))
- simple_rmdir(dir, dentry);
- else
- simple_unlink(dir, dentry);
+ d_delete(dentry);
Not, that doesn't work. You can't just call d_delete() and dput() and
even if I wouldn't advise it. And you also can't do this without
taking the inode lock on the directory.
Agreed on that
simple_rmdir()/simple_unlink() take care to update various inode
fields in the parent dir and handle link counts. This really wants to
be sm like
struct inode *parent_inode;
parent_inode = d_inode(dentry->d_parent);
inode_lock(parent_inode);
if (simple_positive(dentry)) {
dget(dentry);
if (d_is_dir(dentry)
simple_unlink(parent_inode, dentry);
else
simple_unlink(parent_inode, dentry);
d_delete(dentry);
dput(dentry);
}
inode_unlock(parent_inode);
It just slightly annoys me how the simple_ functions change fields in
an inode that is about to be evicted ... it seems redundant; plus we
shouldn't care if the object we're deleting is a directory or file. I
also don't think we need the additional dget because the only consumer
is policy file removal and the opener of that file will have done a
dget. The inode lock now prevents us racing with another remove in the
case of two simultaneous writes.
How about
struct inode *parent_inode;
parent_inode = d_inode(dentry->d_parent);
inode_lock(parent_inode);
if (simple_positive(dentry)) {
drop_nlink(parent_inode);
d_delete(dentry);
dput(dentry);
}
inode_unlock(parent_inode);
James