145 lines
4.2 KiB
C
145 lines
4.2 KiB
C
/* Filesystem index definition
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*
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* Copyright (C) 2004-2007 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 License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*/
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#define FSCACHE_DEBUG_LEVEL CACHE
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#include <linux/module.h>
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#include "internal.h"
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static uint16_t fscache_fsdef_netfs_get_key(const void *cookie_netfs_data,
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void *buffer, uint16_t bufmax);
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static uint16_t fscache_fsdef_netfs_get_aux(const void *cookie_netfs_data,
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void *buffer, uint16_t bufmax);
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static
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enum fscache_checkaux fscache_fsdef_netfs_check_aux(void *cookie_netfs_data,
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const void *data,
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uint16_t datalen);
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/*
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* The root index is owned by FS-Cache itself.
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*
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* When a netfs requests caching facilities, FS-Cache will, if one doesn't
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* already exist, create an entry in the root index with the key being the name
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* of the netfs ("AFS" for example), and the auxiliary data holding the index
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* structure version supplied by the netfs:
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*
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* FSDEF
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* |
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* +-----------+
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* | |
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* NFS AFS
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* [v=1] [v=1]
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*
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* If an entry with the appropriate name does already exist, the version is
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* compared. If the version is different, the entire subtree from that entry
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* will be discarded and a new entry created.
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*
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* The new entry will be an index, and a cookie referring to it will be passed
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* to the netfs. This is then the root handle by which the netfs accesses the
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* cache. It can create whatever objects it likes in that index, including
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* further indices.
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*/
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static struct fscache_cookie_def fscache_fsdef_index_def = {
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.name = ".FS-Cache",
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.type = FSCACHE_COOKIE_TYPE_INDEX,
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};
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struct fscache_cookie fscache_fsdef_index = {
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.usage = ATOMIC_INIT(1),
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.lock = __SPIN_LOCK_UNLOCKED(fscache_fsdef_index.lock),
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.backing_objects = HLIST_HEAD_INIT,
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.def = &fscache_fsdef_index_def,
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};
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EXPORT_SYMBOL(fscache_fsdef_index);
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/*
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* Definition of an entry in the root index. Each entry is an index, keyed to
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* a specific netfs and only applicable to a particular version of the index
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* structure used by that netfs.
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*/
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struct fscache_cookie_def fscache_fsdef_netfs_def = {
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.name = "FSDEF.netfs",
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.type = FSCACHE_COOKIE_TYPE_INDEX,
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.get_key = fscache_fsdef_netfs_get_key,
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.get_aux = fscache_fsdef_netfs_get_aux,
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.check_aux = fscache_fsdef_netfs_check_aux,
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};
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/*
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* get the key data for an FSDEF index record - this is the name of the netfs
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* for which this entry is created
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*/
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static uint16_t fscache_fsdef_netfs_get_key(const void *cookie_netfs_data,
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void *buffer, uint16_t bufmax)
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{
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const struct fscache_netfs *netfs = cookie_netfs_data;
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unsigned klen;
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_enter("{%s.%u},", netfs->name, netfs->version);
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klen = strlen(netfs->name);
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if (klen > bufmax)
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return 0;
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memcpy(buffer, netfs->name, klen);
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return klen;
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}
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/*
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* get the auxiliary data for an FSDEF index record - this is the index
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* structure version number of the netfs for which this version is created
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*/
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static uint16_t fscache_fsdef_netfs_get_aux(const void *cookie_netfs_data,
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void *buffer, uint16_t bufmax)
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{
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const struct fscache_netfs *netfs = cookie_netfs_data;
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unsigned dlen;
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_enter("{%s.%u},", netfs->name, netfs->version);
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dlen = sizeof(uint32_t);
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if (dlen > bufmax)
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return 0;
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memcpy(buffer, &netfs->version, dlen);
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return dlen;
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}
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/*
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* check that the index structure version number stored in the auxiliary data
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* matches the one the netfs gave us
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*/
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static enum fscache_checkaux fscache_fsdef_netfs_check_aux(
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void *cookie_netfs_data,
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const void *data,
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uint16_t datalen)
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{
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struct fscache_netfs *netfs = cookie_netfs_data;
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uint32_t version;
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_enter("{%s},,%hu", netfs->name, datalen);
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if (datalen != sizeof(version)) {
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_leave(" = OBSOLETE [dl=%d v=%zu]", datalen, sizeof(version));
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return FSCACHE_CHECKAUX_OBSOLETE;
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}
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memcpy(&version, data, sizeof(version));
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if (version != netfs->version) {
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_leave(" = OBSOLETE [ver=%x net=%x]", version, netfs->version);
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return FSCACHE_CHECKAUX_OBSOLETE;
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}
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_leave(" = OKAY");
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return FSCACHE_CHECKAUX_OKAY;
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}
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