1 files changed, 771 insertions, 0 deletions

diff --git a/fs/cachefiles/namei.c b/fs/cachefiles/namei.c
new file mode 100644
index 000000000000..4ce818ae39ea
--- /dev/null
+++ b/fs/cachefiles/namei.c
@@ -0,0 +1,771 @@
+/* CacheFiles path walking and related routines
+ *
+ * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public Licence
+ * as published by the Free Software Foundation; either version
+ * 2 of the Licence, or (at your option) any later version.
+ */
+
+#include <linux/module.h>
+#include <linux/sched.h>
+#include <linux/file.h>
+#include <linux/fs.h>
+#include <linux/fsnotify.h>
+#include <linux/quotaops.h>
+#include <linux/xattr.h>
+#include <linux/mount.h>
+#include <linux/namei.h>
+#include <linux/security.h>
+#include "internal.h"
+
+static int cachefiles_wait_bit(void *flags)
+{
+        schedule();
+        return 0;
+}
+
+/*
+ * record the fact that an object is now active
+ */
+static void cachefiles_mark_object_active(struct cachefiles_cache *cache,
+                                          struct cachefiles_object *object)
+{
+        struct cachefiles_object *xobject;
+        struct rb_node **_p, *_parent = NULL;
+        struct dentry *dentry;
+
+        _enter(",%p", object);
+
+try_again:
+        write_lock(&cache->active_lock);
+
+        if (test_and_set_bit(CACHEFILES_OBJECT_ACTIVE, &object->flags))
+                BUG();
+
+        dentry = object->dentry;
+        _p = &cache->active_nodes.rb_node;
+        while (*_p) {
+                _parent = *_p;
+                xobject = rb_entry(_parent,
+                                   struct cachefiles_object, active_node);
+
+                ASSERT(xobject != object);
+
+                if (xobject->dentry > dentry)
+                        _p = &(*_p)->rb_left;
+                else if (xobject->dentry < dentry)
+                        _p = &(*_p)->rb_right;
+                else
+                        goto wait_for_old_object;
+        }
+
+        rb_link_node(&object->active_node, _parent, _p);
+        rb_insert_color(&object->active_node, &cache->active_nodes);
+
+        write_unlock(&cache->active_lock);
+        _leave("");
+        return;
+
+        /* an old object from a previous incarnation is hogging the slot - we
+         * need to wait for it to be destroyed */
+wait_for_old_object:
+        if (xobject->fscache.state < FSCACHE_OBJECT_DYING) {
+                printk(KERN_ERR "\n");
+                printk(KERN_ERR "CacheFiles: Error:"
+                       " Unexpected object collision\n");
+                printk(KERN_ERR "xobject: OBJ%x\n",
+                       xobject->fscache.debug_id);
+                printk(KERN_ERR "xobjstate=%s\n",
+                       fscache_object_states[xobject->fscache.state]);
+                printk(KERN_ERR "xobjflags=%lx\n", xobject->fscache.flags);
+                printk(KERN_ERR "xobjevent=%lx [%lx]\n",
+                       xobject->fscache.events, xobject->fscache.event_mask);
+                printk(KERN_ERR "xops=%u inp=%u exc=%u\n",
+                       xobject->fscache.n_ops, xobject->fscache.n_in_progress,
+                       xobject->fscache.n_exclusive);
+                printk(KERN_ERR "xcookie=%p [pr=%p nd=%p fl=%lx]\n",
+                       xobject->fscache.cookie,
+                       xobject->fscache.cookie->parent,
+                       xobject->fscache.cookie->netfs_data,
+                       xobject->fscache.cookie->flags);
+                printk(KERN_ERR "xparent=%p\n",
+                       xobject->fscache.parent);
+                printk(KERN_ERR "object: OBJ%x\n",
+                       object->fscache.debug_id);
+                printk(KERN_ERR "cookie=%p [pr=%p nd=%p fl=%lx]\n",
+                       object->fscache.cookie,
+                       object->fscache.cookie->parent,
+                       object->fscache.cookie->netfs_data,
+                       object->fscache.cookie->flags);
+                printk(KERN_ERR "parent=%p\n",
+                       object->fscache.parent);
+                BUG();
+        }
+        atomic_inc(&xobject->usage);
+        write_unlock(&cache->active_lock);
+
+        _debug(">>> wait");
+        wait_on_bit(&xobject->flags, CACHEFILES_OBJECT_ACTIVE,
+                    cachefiles_wait_bit, TASK_UNINTERRUPTIBLE);
+        _debug("<<< waited");
+
+        cache->cache.ops->put_object(&xobject->fscache);
+        goto try_again;
+}
+
+/*
+ * delete an object representation from the cache
+ * - file backed objects are unlinked
+ * - directory backed objects are stuffed into the graveyard for userspace to
+ *   delete
+ * - unlocks the directory mutex
+ */
+static int cachefiles_bury_object(struct cachefiles_cache *cache,
+                                  struct dentry *dir,
+                                  struct dentry *rep)
+{
+        struct dentry *grave, *trap;
+        char nbuffer[8 + 8 + 1];
+        int ret;
+
+        _enter(",'%*.*s','%*.*s'",
+               dir->d_name.len, dir->d_name.len, dir->d_name.name,
+               rep->d_name.len, rep->d_name.len, rep->d_name.name);
+
+        /* non-directories can just be unlinked */
+        if (!S_ISDIR(rep->d_inode->i_mode)) {
+                _debug("unlink stale object");
+                ret = vfs_unlink(dir->d_inode, rep);
+
+                mutex_unlock(&dir->d_inode->i_mutex);
+
+                if (ret == -EIO)
+                        cachefiles_io_error(cache, "Unlink failed");
+
+                _leave(" = %d", ret);
+                return ret;
+        }
+
+        /* directories have to be moved to the graveyard */
+        _debug("move stale object to graveyard");
+        mutex_unlock(&dir->d_inode->i_mutex);
+
+try_again:
+        /* first step is to make up a grave dentry in the graveyard */
+        sprintf(nbuffer, "%08x%08x",
+                (uint32_t) get_seconds(),
+                (uint32_t) atomic_inc_return(&cache->gravecounter));
+
+        /* do the multiway lock magic */
+        trap = lock_rename(cache->graveyard, dir);
+
+        /* do some checks before getting the grave dentry */
+        if (rep->d_parent != dir) {
+                /* the entry was probably culled when we dropped the parent dir
+                 * lock */
+                unlock_rename(cache->graveyard, dir);
+                _leave(" = 0 [culled?]");
+                return 0;
+        }
+
+        if (!S_ISDIR(cache->graveyard->d_inode->i_mode)) {
+                unlock_rename(cache->graveyard, dir);
+                cachefiles_io_error(cache, "Graveyard no longer a directory");
+                return -EIO;
+        }
+
+        if (trap == rep) {
+                unlock_rename(cache->graveyard, dir);
+                cachefiles_io_error(cache, "May not make directory loop");
+                return -EIO;
+        }
+
+        if (d_mountpoint(rep)) {
+                unlock_rename(cache->graveyard, dir);
+                cachefiles_io_error(cache, "Mountpoint in cache");
+                return -EIO;
+        }
+
+        grave = lookup_one_len(nbuffer, cache->graveyard, strlen(nbuffer));
+        if (IS_ERR(grave)) {
+                unlock_rename(cache->graveyard, dir);
+
+                if (PTR_ERR(grave) == -ENOMEM) {
+                        _leave(" = -ENOMEM");
+                        return -ENOMEM;
+                }
+
+                cachefiles_io_error(cache, "Lookup error %ld",
+                                    PTR_ERR(grave));
+                return -EIO;
+        }
+
+        if (grave->d_inode) {
+                unlock_rename(cache->graveyard, dir);
+                dput(grave);
+                grave = NULL;
+                cond_resched();
+                goto try_again;
+        }
+
+        if (d_mountpoint(grave)) {
+                unlock_rename(cache->graveyard, dir);
+                dput(grave);
+                cachefiles_io_error(cache, "Mountpoint in graveyard");
+                return -EIO;
+        }
+
+        /* target should not be an ancestor of source */
+        if (trap == grave) {
+                unlock_rename(cache->graveyard, dir);
+                dput(grave);
+                cachefiles_io_error(cache, "May not make directory loop");
+                return -EIO;
+        }
+
+        /* attempt the rename */
+        ret = vfs_rename(dir->d_inode, rep, cache->graveyard->d_inode, grave);
+        if (ret != 0 && ret != -ENOMEM)
+                cachefiles_io_error(cache, "Rename failed with error %d", ret);
+
+        unlock_rename(cache->graveyard, dir);
+        dput(grave);
+        _leave(" = 0");
+        return 0;
+}
+
+/*
+ * delete an object representation from the cache
+ */
+int cachefiles_delete_object(struct cachefiles_cache *cache,
+                             struct cachefiles_object *object)
+{
+        struct dentry *dir;
+        int ret;
+
+        _enter(",{%p}", object->dentry);
+
+        ASSERT(object->dentry);
+        ASSERT(object->dentry->d_inode);
+        ASSERT(object->dentry->d_parent);
+
+        dir = dget_parent(object->dentry);
+
+        mutex_lock(&dir->d_inode->i_mutex);
+        ret = cachefiles_bury_object(cache, dir, object->dentry);
+
+        dput(dir);
+        _leave(" = %d", ret);
+        return ret;
+}
+
+/*
+ * walk from the parent object to the child object through the backing
+ * filesystem, creating directories as we go
+ */
+int cachefiles_walk_to_object(struct cachefiles_object *parent,
+                              struct cachefiles_object *object,
+                              const char *key,
+                              struct cachefiles_xattr *auxdata)
+{
+        struct cachefiles_cache *cache;
+        struct dentry *dir, *next = NULL;
+        unsigned long start;
+        const char *name;
+        int ret, nlen;
+
+        _enter("{%p},,%s,", parent->dentry, key);
+
+        cache = container_of(parent->fscache.cache,
+                             struct cachefiles_cache, cache);
+
+        ASSERT(parent->dentry);
+        ASSERT(parent->dentry->d_inode);
+
+        if (!(S_ISDIR(parent->dentry->d_inode->i_mode))) {
+                // TODO: convert file to dir
+                _leave("looking up in none directory");
+                return -ENOBUFS;
+        }
+
+        dir = dget(parent->dentry);
+
+advance:
+        /* attempt to transit the first directory component */
+        name = key;
+        nlen = strlen(key);
+
+        /* key ends in a double NUL */
+        key = key + nlen + 1;
+        if (!*key)
+                key = NULL;
+
+lookup_again:
+        /* search the current directory for the element name */
+        _debug("lookup '%s'", name);
+
+        mutex_lock(&dir->d_inode->i_mutex);
+
+        start = jiffies;
+        next = lookup_one_len(name, dir, nlen);
+        cachefiles_hist(cachefiles_lookup_histogram, start);
+        if (IS_ERR(next))
+                goto lookup_error;
+
+        _debug("next -> %p %s", next, next->d_inode ? "positive" : "negative");
+
+        if (!key)
+                object->new = !next->d_inode;
+
+        /* if this element of the path doesn't exist, then the lookup phase
+         * failed, and we can release any readers in the certain knowledge that
+         * there's nothing for them to actually read */
+        if (!next->d_inode)
+                fscache_object_lookup_negative(&object->fscache);
+
+        /* we need to create the object if it's negative */
+        if (key || object->type == FSCACHE_COOKIE_TYPE_INDEX) {
+                /* index objects and intervening tree levels must be subdirs */
+                if (!next->d_inode) {
+                        ret = cachefiles_has_space(cache, 1, 0);
+                        if (ret < 0)
+                                goto create_error;
+
+                        start = jiffies;
+                        ret = vfs_mkdir(dir->d_inode, next, 0);
+                        cachefiles_hist(cachefiles_mkdir_histogram, start);
+                        if (ret < 0)
+                                goto create_error;
+
+                        ASSERT(next->d_inode);
+
+                        _debug("mkdir -> %p{%p{ino=%lu}}",
+                               next, next->d_inode, next->d_inode->i_ino);
+
+                } else if (!S_ISDIR(next->d_inode->i_mode)) {
+                        kerror("inode %lu is not a directory",
+                               next->d_inode->i_ino);
+                        ret = -ENOBUFS;
+                        goto error;
+                }
+
+        } else {
+                /* non-index objects start out life as files */
+                if (!next->d_inode) {
+                        ret = cachefiles_has_space(cache, 1, 0);
+                        if (ret < 0)
+                                goto create_error;
+
+                        start = jiffies;
+                        ret = vfs_create(dir->d_inode, next, S_IFREG, NULL);
+                        cachefiles_hist(cachefiles_create_histogram, start);
+                        if (ret < 0)
+                                goto create_error;
+
+                        ASSERT(next->d_inode);
+
+                        _debug("create -> %p{%p{ino=%lu}}",
+                               next, next->d_inode, next->d_inode->i_ino);
+
+                } else if (!S_ISDIR(next->d_inode->i_mode) &&
+                           !S_ISREG(next->d_inode->i_mode)
+                           ) {
+                        kerror("inode %lu is not a file or directory",
+                               next->d_inode->i_ino);
+                        ret = -ENOBUFS;
+                        goto error;
+                }
+        }
+
+        /* process the next component */
+        if (key) {
+                _debug("advance");
+                mutex_unlock(&dir->d_inode->i_mutex);
+                dput(dir);
+                dir = next;
+                next = NULL;
+                goto advance;
+        }
+
+        /* we've found the object we were looking for */
+        object->dentry = next;
+
+        /* if we've found that the terminal object exists, then we need to
+         * check its attributes and delete it if it's out of date */
+        if (!object->new) {
+                _debug("validate '%*.*s'",
+                       next->d_name.len, next->d_name.len, next->d_name.name);
+
+                ret = cachefiles_check_object_xattr(object, auxdata);
+                if (ret == -ESTALE) {
+                        /* delete the object (the deleter drops the directory
+                         * mutex) */
+                        object->dentry = NULL;
+
+                        ret = cachefiles_bury_object(cache, dir, next);
+                        dput(next);
+                        next = NULL;
+
+                        if (ret < 0)
+                                goto delete_error;
+
+                        _debug("redo lookup");
+                        goto lookup_again;
+                }
+        }
+
+        /* note that we're now using this object */
+        cachefiles_mark_object_active(cache, object);
+
+        mutex_unlock(&dir->d_inode->i_mutex);
+        dput(dir);
+        dir = NULL;
+
+        _debug("=== OBTAINED_OBJECT ===");
+
+        if (object->new) {
+                /* attach data to a newly constructed terminal object */
+                ret = cachefiles_set_object_xattr(object, auxdata);
+                if (ret < 0)
+                        goto check_error;
+        } else {
+                /* always update the atime on an object we've just looked up
+                 * (this is used to keep track of culling, and atimes are only
+                 * updated by read, write and readdir but not lookup or
+                 * open) */
+                touch_atime(cache->mnt, next);
+        }
+
+        /* open a file interface onto a data file */
+        if (object->type != FSCACHE_COOKIE_TYPE_INDEX) {
+                if (S_ISREG(object->dentry->d_inode->i_mode)) {
+                        const struct address_space_operations *aops;
+
+                        ret = -EPERM;
+                        aops = object->dentry->d_inode->i_mapping->a_ops;
+                        if (!aops->bmap)
+                                goto check_error;
+
+                        object->backer = object->dentry;
+                } else {
+                        BUG(); // TODO: open file in data-class subdir
+                }
+        }
+
+        object->new = 0;
+        fscache_obtained_object(&object->fscache);
+
+        _leave(" = 0 [%lu]", object->dentry->d_inode->i_ino);
+        return 0;
+
+create_error:
+        _debug("create error %d", ret);
+        if (ret == -EIO)
+                cachefiles_io_error(cache, "Create/mkdir failed");
+        goto error;
+
+check_error:
+        _debug("check error %d", ret);
+        write_lock(&cache->active_lock);
+        rb_erase(&object->active_node, &cache->active_nodes);
+        clear_bit(CACHEFILES_OBJECT_ACTIVE, &object->flags);
+        wake_up_bit(&object->flags, CACHEFILES_OBJECT_ACTIVE);
+        write_unlock(&cache->active_lock);
+
+        dput(object->dentry);
+        object->dentry = NULL;
+        goto error_out;
+
+delete_error:
+        _debug("delete error %d", ret);
+        goto error_out2;
+
+lookup_error:
+        _debug("lookup error %ld", PTR_ERR(next));
+        ret = PTR_ERR(next);
+        if (ret == -EIO)
+                cachefiles_io_error(cache, "Lookup failed");
+        next = NULL;
+error:
+        mutex_unlock(&dir->d_inode->i_mutex);
+        dput(next);
+error_out2:
+        dput(dir);
+error_out:
+        if (ret == -ENOSPC)
+                ret = -ENOBUFS;
+
+        _leave(" = error %d", -ret);
+        return ret;
+}
+
+/*
+ * get a subdirectory
+ */
+struct dentry *cachefiles_get_directory(struct cachefiles_cache *cache,
+                                        struct dentry *dir,
+                                        const char *dirname)
+{
+        struct dentry *subdir;
+        unsigned long start;
+        int ret;
+
+        _enter(",,%s", dirname);
+
+        /* search the current directory for the element name */
+        mutex_lock(&dir->d_inode->i_mutex);
+
+        start = jiffies;
+        subdir = lookup_one_len(dirname, dir, strlen(dirname));
+        cachefiles_hist(cachefiles_lookup_histogram, start);
+        if (IS_ERR(subdir)) {
+                if (PTR_ERR(subdir) == -ENOMEM)
+                        goto nomem_d_alloc;
+                goto lookup_error;
+        }
+
+        _debug("subdir -> %p %s",
+               subdir, subdir->d_inode ? "positive" : "negative");
+
+        /* we need to create the subdir if it doesn't exist yet */
+        if (!subdir->d_inode) {
+                ret = cachefiles_has_space(cache, 1, 0);
+                if (ret < 0)
+                        goto mkdir_error;
+
+                _debug("attempt mkdir");
+
+                ret = vfs_mkdir(dir->d_inode, subdir, 0700);
+                if (ret < 0)
+                        goto mkdir_error;
+
+                ASSERT(subdir->d_inode);
+
+                _debug("mkdir -> %p{%p{ino=%lu}}",
+                       subdir,
+                       subdir->d_inode,
+                       subdir->d_inode->i_ino);
+        }
+
+        mutex_unlock(&dir->d_inode->i_mutex);
+
+        /* we need to make sure the subdir is a directory */
+        ASSERT(subdir->d_inode);
+
+        if (!S_ISDIR(subdir->d_inode->i_mode)) {
+                kerror("%s is not a directory", dirname);
+                ret = -EIO;
+                goto check_error;
+        }
+
+        ret = -EPERM;
+        if (!subdir->d_inode->i_op ||
+            !subdir->d_inode->i_op->setxattr ||
+            !subdir->d_inode->i_op->getxattr ||
+            !subdir->d_inode->i_op->lookup ||
+            !subdir->d_inode->i_op->mkdir ||
+            !subdir->d_inode->i_op->create ||
+            !subdir->d_inode->i_op->rename ||
+            !subdir->d_inode->i_op->rmdir ||
+            !subdir->d_inode->i_op->unlink)
+                goto check_error;
+
+        _leave(" = [%lu]", subdir->d_inode->i_ino);
+        return subdir;
+
+check_error:
+        dput(subdir);
+        _leave(" = %d [check]", ret);
+        return ERR_PTR(ret);
+
+mkdir_error:
+        mutex_unlock(&dir->d_inode->i_mutex);
+        dput(subdir);
+        kerror("mkdir %s failed with error %d", dirname, ret);
+        return ERR_PTR(ret);
+
+lookup_error:
+        mutex_unlock(&dir->d_inode->i_mutex);
+        ret = PTR_ERR(subdir);
+        kerror("Lookup %s failed with error %d", dirname, ret);
+        return ERR_PTR(ret);
+
+nomem_d_alloc:
+        mutex_unlock(&dir->d_inode->i_mutex);
+        _leave(" = -ENOMEM");
+        return ERR_PTR(-ENOMEM);
+}
+
+/*
+ * find out if an object is in use or not
+ * - if finds object and it's not in use:
+ *   - returns a pointer to the object and a reference on it
+ *   - returns with the directory locked
+ */
+static struct dentry *cachefiles_check_active(struct cachefiles_cache *cache,
+                                              struct dentry *dir,
+                                              char *filename)
+{
+        struct cachefiles_object *object;
+        struct rb_node *_n;
+        struct dentry *victim;
+        unsigned long start;
+        int ret;
+
+        //_enter(",%*.*s/,%s",
+        //       dir->d_name.len, dir->d_name.len, dir->d_name.name, filename);
+
+        /* look up the victim */
+        mutex_lock_nested(&dir->d_inode->i_mutex, 1);
+
+        start = jiffies;
+        victim = lookup_one_len(filename, dir, strlen(filename));
+        cachefiles_hist(cachefiles_lookup_histogram, start);
+        if (IS_ERR(victim))
+                goto lookup_error;
+
+        //_debug("victim -> %p %s",
+        //       victim, victim->d_inode ? "positive" : "negative");
+
+        /* if the object is no longer there then we probably retired the object
+         * at the netfs's request whilst the cull was in progress
+         */
+        if (!victim->d_inode) {
+                mutex_unlock(&dir->d_inode->i_mutex);
+                dput(victim);
+                _leave(" = -ENOENT [absent]");
+                return ERR_PTR(-ENOENT);
+        }
+
+        /* check to see if we're using this object */
+        read_lock(&cache->active_lock);
+
+        _n = cache->active_nodes.rb_node;
+
+        while (_n) {
+                object = rb_entry(_n, struct cachefiles_object, active_node);
+
+                if (object->dentry > victim)
+                        _n = _n->rb_left;
+                else if (object->dentry < victim)
+                        _n = _n->rb_right;
+                else
+                        goto object_in_use;
+        }
+
+        read_unlock(&cache->active_lock);
+
+        //_leave(" = %p", victim);
+        return victim;
+
+object_in_use:
+        read_unlock(&cache->active_lock);
+        mutex_unlock(&dir->d_inode->i_mutex);
+        dput(victim);
+        //_leave(" = -EBUSY [in use]");
+        return ERR_PTR(-EBUSY);
+
+lookup_error:
+        mutex_unlock(&dir->d_inode->i_mutex);
+        ret = PTR_ERR(victim);
+        if (ret == -ENOENT) {
+                /* file or dir now absent - probably retired by netfs */
+                _leave(" = -ESTALE [absent]");
+                return ERR_PTR(-ESTALE);
+        }
+
+        if (ret == -EIO) {
+                cachefiles_io_error(cache, "Lookup failed");
+        } else if (ret != -ENOMEM) {
+                kerror("Internal error: %d", ret);
+                ret = -EIO;
+        }
+
+        _leave(" = %d", ret);
+        return ERR_PTR(ret);
+}
+
+/*
+ * cull an object if it's not in use
+ * - called only by cache manager daemon
+ */
+int cachefiles_cull(struct cachefiles_cache *cache, struct dentry *dir,
+                    char *filename)
+{
+        struct dentry *victim;
+        int ret;
+
+        _enter(",%*.*s/,%s",
+               dir->d_name.len, dir->d_name.len, dir->d_name.name, filename);
+
+        victim = cachefiles_check_active(cache, dir, filename);
+        if (IS_ERR(victim))
+                return PTR_ERR(victim);
+
+        _debug("victim -> %p %s",
+               victim, victim->d_inode ? "positive" : "negative");
+
+        /* okay... the victim is not being used so we can cull it
+         * - start by marking it as stale
+         */
+        _debug("victim is cullable");
+
+        ret = cachefiles_remove_object_xattr(cache, victim);
+        if (ret < 0)
+                goto error_unlock;
+
+        /*  actually remove the victim (drops the dir mutex) */
+        _debug("bury");
+
+        ret = cachefiles_bury_object(cache, dir, victim);
+        if (ret < 0)
+                goto error;
+
+        dput(victim);
+        _leave(" = 0");
+        return 0;
+
+error_unlock:
+        mutex_unlock(&dir->d_inode->i_mutex);
+error:
+        dput(victim);
+        if (ret == -ENOENT) {
+                /* file or dir now absent - probably retired by netfs */
+                _leave(" = -ESTALE [absent]");
+                return -ESTALE;
+        }
+
+        if (ret != -ENOMEM) {
+                kerror("Internal error: %d", ret);
+                ret = -EIO;
+        }
+
+        _leave(" = %d", ret);
+        return ret;
+}
+
+/*
+ * find out if an object is in use or not
+ * - called only by cache manager daemon
+ * - returns -EBUSY or 0 to indicate whether an object is in use or not
+ */
+int cachefiles_check_in_use(struct cachefiles_cache *cache, struct dentry *dir,
+                            char *filename)
+{
+        struct dentry *victim;
+
+        //_enter(",%*.*s/,%s",
+        //       dir->d_name.len, dir->d_name.len, dir->d_name.name, filename);
+
+        victim = cachefiles_check_active(cache, dir, filename);
+        if (IS_ERR(victim))
+                return PTR_ERR(victim);
+
+        mutex_unlock(&dir->d_inode->i_mutex);
+        dput(victim);
+        //_leave(" = 0");
+        return 0;
+}