On Tue, Apr 02, 2019 at 08:45:50AM -0700, Eric Biggers wrote:
> From: Eric Biggers <[email protected]>
>
> When a filesystem encryption key is removed, we need all files which had
> been "unlocked" (had ->i_crypt_info set up) with it to appear "locked"
> again. This is most easily done by evicting the inodes. This can
> currently be done using 'echo 2 > /proc/sys/vm/drop_caches'; however,
> that is overkill and not usable by non-root users.
>
> To evict just the needed inodes we also need the ability to evict those
> inodes' dentries, since an inode is pinned by its dentries. Therefore,
> add a function shrink_dcache_inode() which iterates through an inode's
> dentries and evicts any unused ones as well as any unused descendants
> (since there may be negative dentries pinning the inode's dentries).
Huh?
> + * Evict all unused aliases of the specified inode from the dcache. This is
> + * intended to be used when trying to evict a specific inode, since inodes
> are
> + * pinned by their dentries. We also have to descend to ->d_subdirs for each
> + * alias, since aliases may be pinned by negative child dentries.
> + */
> +void shrink_dcache_inode(struct inode *inode)
> +{
> + for (;;) {
> + struct select_data data;
> + struct dentry *dentry;
> +
> + INIT_LIST_HEAD(&data.dispose);
> + data.start = NULL;
> + data.found = 0;
> +
> + spin_lock(&inode->i_lock);
> + hlist_for_each_entry(dentry, &inode->i_dentry, d_u.d_alias)
> + d_walk(dentry, &data, select_collect);
> + spin_unlock(&inode->i_lock);
> +
> + if (!data.found)
> + break;
> +
> + shrink_dentry_list(&data.dispose);
> + cond_resched();
This is... odd. What's wrong with
if (S_ISDIR(inode->i_mode)) {
dentry = d_find_any_alias(inode);
if (dentry) {
shrink_dcache_parent(dentry);
dput(dentry);
}
}
d_prune_aliases(inode);
instead of that thing?
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