726dd7ff10
Add functions to register and unregister a network filesystem or other client of the FS-Cache service. This allocates and releases the cookie representing the top-level index for a netfs, and makes it available to the netfs. If the FS-Cache facility is disabled, then the calls are optimised away at compile time. Note that whilst this patch may appear to work with FS-Cache enabled and a netfs attempting to use it, it will leak the cookie it allocates for the netfs as fscache_relinquish_cookie() is implemented in a later patch. This will cause the slab code to emit a warning when the module is removed. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Steve Dickson <steved@redhat.com> Acked-by: Trond Myklebust <Trond.Myklebust@netapp.com> Acked-by: Al Viro <viro@zeniv.linux.org.uk> Tested-by: Daire Byrne <Daire.Byrne@framestore.com>
104 lines
2.6 KiB
C
104 lines
2.6 KiB
C
/* FS-Cache netfs (client) registration
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*
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* Copyright (C) 2008 Red Hat, Inc. All Rights Reserved.
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* Written by David Howells (dhowells@redhat.com)
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public Licence
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* as published by the Free Software Foundation; either version
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* 2 of the Licence, or (at your option) any later version.
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*/
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#define FSCACHE_DEBUG_LEVEL COOKIE
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#include <linux/module.h>
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#include <linux/slab.h>
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#include "internal.h"
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static LIST_HEAD(fscache_netfs_list);
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/*
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* register a network filesystem for caching
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*/
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int __fscache_register_netfs(struct fscache_netfs *netfs)
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{
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struct fscache_netfs *ptr;
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int ret;
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_enter("{%s}", netfs->name);
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INIT_LIST_HEAD(&netfs->link);
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/* allocate a cookie for the primary index */
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netfs->primary_index =
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kmem_cache_zalloc(fscache_cookie_jar, GFP_KERNEL);
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if (!netfs->primary_index) {
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_leave(" = -ENOMEM");
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return -ENOMEM;
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}
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/* initialise the primary index cookie */
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atomic_set(&netfs->primary_index->usage, 1);
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atomic_set(&netfs->primary_index->n_children, 0);
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netfs->primary_index->def = &fscache_fsdef_netfs_def;
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netfs->primary_index->parent = &fscache_fsdef_index;
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netfs->primary_index->netfs_data = netfs;
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atomic_inc(&netfs->primary_index->parent->usage);
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atomic_inc(&netfs->primary_index->parent->n_children);
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spin_lock_init(&netfs->primary_index->lock);
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INIT_HLIST_HEAD(&netfs->primary_index->backing_objects);
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/* check the netfs type is not already present */
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down_write(&fscache_addremove_sem);
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ret = -EEXIST;
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list_for_each_entry(ptr, &fscache_netfs_list, link) {
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if (strcmp(ptr->name, netfs->name) == 0)
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goto already_registered;
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}
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list_add(&netfs->link, &fscache_netfs_list);
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ret = 0;
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printk(KERN_NOTICE "FS-Cache: Netfs '%s' registered for caching\n",
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netfs->name);
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already_registered:
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up_write(&fscache_addremove_sem);
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if (ret < 0) {
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netfs->primary_index->parent = NULL;
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__fscache_cookie_put(netfs->primary_index);
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netfs->primary_index = NULL;
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}
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_leave(" = %d", ret);
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return ret;
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}
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EXPORT_SYMBOL(__fscache_register_netfs);
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/*
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* unregister a network filesystem from the cache
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* - all cookies must have been released first
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*/
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void __fscache_unregister_netfs(struct fscache_netfs *netfs)
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{
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_enter("{%s.%u}", netfs->name, netfs->version);
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down_write(&fscache_addremove_sem);
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list_del(&netfs->link);
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fscache_relinquish_cookie(netfs->primary_index, 0);
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up_write(&fscache_addremove_sem);
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printk(KERN_NOTICE "FS-Cache: Netfs '%s' unregistered from caching\n",
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netfs->name);
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_leave("");
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}
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EXPORT_SYMBOL(__fscache_unregister_netfs);
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