diff options
author | David Howells <dhowells@redhat.com> | 2009-04-03 17:42:38 +0200 |
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committer | David Howells <dhowells@redhat.com> | 2009-04-03 17:42:38 +0200 |
commit | 726dd7ff10c217dd74329c94643dc8ebea27334b (patch) | |
tree | 9bd5b011f945fca4f1b057f7e7750414b1fd9fbd /fs/fscache/netfs.c | |
parent | FS-Cache: Provide a slab for cookie allocation (diff) | |
download | linux-726dd7ff10c217dd74329c94643dc8ebea27334b.tar.xz linux-726dd7ff10c217dd74329c94643dc8ebea27334b.zip |
FS-Cache: Add netfs registration
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>
Diffstat (limited to 'fs/fscache/netfs.c')
-rw-r--r-- | fs/fscache/netfs.c | 103 |
1 files changed, 103 insertions, 0 deletions
diff --git a/fs/fscache/netfs.c b/fs/fscache/netfs.c new file mode 100644 index 000000000000..e028b8eb1c40 --- /dev/null +++ b/fs/fscache/netfs.c @@ -0,0 +1,103 @@ +/* FS-Cache netfs (client) registration + * + * Copyright (C) 2008 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. + */ + +#define FSCACHE_DEBUG_LEVEL COOKIE +#include <linux/module.h> +#include <linux/slab.h> +#include "internal.h" + +static LIST_HEAD(fscache_netfs_list); + +/* + * register a network filesystem for caching + */ +int __fscache_register_netfs(struct fscache_netfs *netfs) +{ + struct fscache_netfs *ptr; + int ret; + + _enter("{%s}", netfs->name); + + INIT_LIST_HEAD(&netfs->link); + + /* allocate a cookie for the primary index */ + netfs->primary_index = + kmem_cache_zalloc(fscache_cookie_jar, GFP_KERNEL); + + if (!netfs->primary_index) { + _leave(" = -ENOMEM"); + return -ENOMEM; + } + + /* initialise the primary index cookie */ + atomic_set(&netfs->primary_index->usage, 1); + atomic_set(&netfs->primary_index->n_children, 0); + + netfs->primary_index->def = &fscache_fsdef_netfs_def; + netfs->primary_index->parent = &fscache_fsdef_index; + netfs->primary_index->netfs_data = netfs; + + atomic_inc(&netfs->primary_index->parent->usage); + atomic_inc(&netfs->primary_index->parent->n_children); + + spin_lock_init(&netfs->primary_index->lock); + INIT_HLIST_HEAD(&netfs->primary_index->backing_objects); + + /* check the netfs type is not already present */ + down_write(&fscache_addremove_sem); + + ret = -EEXIST; + list_for_each_entry(ptr, &fscache_netfs_list, link) { + if (strcmp(ptr->name, netfs->name) == 0) + goto already_registered; + } + + list_add(&netfs->link, &fscache_netfs_list); + ret = 0; + + printk(KERN_NOTICE "FS-Cache: Netfs '%s' registered for caching\n", + netfs->name); + +already_registered: + up_write(&fscache_addremove_sem); + + if (ret < 0) { + netfs->primary_index->parent = NULL; + __fscache_cookie_put(netfs->primary_index); + netfs->primary_index = NULL; + } + + _leave(" = %d", ret); + return ret; +} +EXPORT_SYMBOL(__fscache_register_netfs); + +/* + * unregister a network filesystem from the cache + * - all cookies must have been released first + */ +void __fscache_unregister_netfs(struct fscache_netfs *netfs) +{ + _enter("{%s.%u}", netfs->name, netfs->version); + + down_write(&fscache_addremove_sem); + + list_del(&netfs->link); + fscache_relinquish_cookie(netfs->primary_index, 0); + + up_write(&fscache_addremove_sem); + + printk(KERN_NOTICE "FS-Cache: Netfs '%s' unregistered from caching\n", + netfs->name); + + _leave(""); +} +EXPORT_SYMBOL(__fscache_unregister_netfs); |