Messages in this thread | | | Date | Thu, 19 Oct 2006 21:40:56 -0700 | From | Andrew Morton <> | Subject | Re: [PATCH 1/2] VFS: Make d_materialise_unique() enforce directory uniqueness |
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On Thu, 19 Oct 2006 17:03:58 -0400 Trond Myklebust <Trond.Myklebust@netapp.com> wrote:
> +static struct dentry *__d_unalias(struct dentry *dentry, struct dentry *alias) > +{ > + struct mutex *m1 = NULL, *m2 = NULL; > + struct dentry *ret; > + > + /* If alias and dentry share a parent, then no extra locks required */ > + if (alias->d_parent == dentry->d_parent) > + goto out_unalias; > + > + /* Check for loops */ > + ret = ERR_PTR(-ELOOP); > + if (d_isparent(alias, dentry)) > + goto out_err; > + > + /* See lock_rename() */ > + ret = ERR_PTR(-EBUSY); > + if (!mutex_trylock(&dentry->d_sb->s_vfs_rename_mutex)) > + goto out_err; > + m1 = &dentry->d_sb->s_vfs_rename_mutex; > + if (!mutex_trylock(&alias->d_parent->d_inode->i_mutex)) > + goto out_err; > + m2 = &alias->d_parent->d_inode->i_mutex; > +out_unalias: > + d_move_locked(alias, dentry); > + ret = alias; > +out_err: > + spin_unlock(&dcache_lock); > + if (m2) > + mutex_unlock(m2); > + if (m1) > + mutex_unlock(m1); > + return ret; > +}
The locking in there is, of course, gruesome. There is no way in which it can be made reliable?
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