diff options
| -rw-r--r-- | fs/fscache/Makefile | 1 | ||||
| -rw-r--r-- | fs/fscache/fsdef.c | 144 | ||||
| -rw-r--r-- | fs/fscache/internal.h | 6 |
3 files changed, 151 insertions, 0 deletions
diff --git a/fs/fscache/Makefile b/fs/fscache/Makefile index 1384823a160c..bc1f3b9d811a 100644 --- a/fs/fscache/Makefile +++ b/fs/fscache/Makefile @@ -3,6 +3,7 @@ # fscache-y := \ + fsdef.o \ main.o fscache-$(CONFIG_PROC_FS) += proc.o diff --git a/fs/fscache/fsdef.c b/fs/fscache/fsdef.c new file mode 100644 index 000000000000..f5b4baee7352 --- /dev/null +++ b/fs/fscache/fsdef.c @@ -0,0 +1,144 @@ +/* Filesystem index definition + * + * Copyright (C) 2004-2007 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 License + * as published by the Free Software Foundation; either version + * 2 of the License, or (at your option) any later version. + */ + +#define FSCACHE_DEBUG_LEVEL CACHE +#include <linux/module.h> +#include "internal.h" + +static uint16_t fscache_fsdef_netfs_get_key(const void *cookie_netfs_data, + void *buffer, uint16_t bufmax); + +static uint16_t fscache_fsdef_netfs_get_aux(const void *cookie_netfs_data, + void *buffer, uint16_t bufmax); + +static +enum fscache_checkaux fscache_fsdef_netfs_check_aux(void *cookie_netfs_data, + const void *data, + uint16_t datalen); + +/* + * The root index is owned by FS-Cache itself. + * + * When a netfs requests caching facilities, FS-Cache will, if one doesn't + * already exist, create an entry in the root index with the key being the name + * of the netfs ("AFS" for example), and the auxiliary data holding the index + * structure version supplied by the netfs: + * + * FSDEF + * | + * +-----------+ + * | | + * NFS AFS + * [v=1] [v=1] + * + * If an entry with the appropriate name does already exist, the version is + * compared. If the version is different, the entire subtree from that entry + * will be discarded and a new entry created. + * + * The new entry will be an index, and a cookie referring to it will be passed + * to the netfs. This is then the root handle by which the netfs accesses the + * cache. It can create whatever objects it likes in that index, including + * further indices. + */ +static struct fscache_cookie_def fscache_fsdef_index_def = { + .name = ".FS-Cache", + .type = FSCACHE_COOKIE_TYPE_INDEX, +}; + +struct fscache_cookie fscache_fsdef_index = { + .usage = ATOMIC_INIT(1), + .lock = __SPIN_LOCK_UNLOCKED(fscache_fsdef_index.lock), + .backing_objects = HLIST_HEAD_INIT, + .def = &fscache_fsdef_index_def, +}; +EXPORT_SYMBOL(fscache_fsdef_index); + +/* + * Definition of an entry in the root index. Each entry is an index, keyed to + * a specific netfs and only applicable to a particular version of the index + * structure used by that netfs. + */ +struct fscache_cookie_def fscache_fsdef_netfs_def = { + .name = "FSDEF.netfs", + .type = FSCACHE_COOKIE_TYPE_INDEX, + .get_key = fscache_fsdef_netfs_get_key, + .get_aux = fscache_fsdef_netfs_get_aux, + .check_aux = fscache_fsdef_netfs_check_aux, +}; + +/* + * get the key data for an FSDEF index record - this is the name of the netfs + * for which this entry is created + */ +static uint16_t fscache_fsdef_netfs_get_key(const void *cookie_netfs_data, + void *buffer, uint16_t bufmax) +{ + const struct fscache_netfs *netfs = cookie_netfs_data; + unsigned klen; + + _enter("{%s.%u},", netfs->name, netfs->version); + + klen = strlen(netfs->name); + if (klen > bufmax) + return 0; + + memcpy(buffer, netfs->name, klen); + return klen; +} + +/* + * get the auxiliary data for an FSDEF index record - this is the index + * structure version number of the netfs for which this version is created + */ +static uint16_t fscache_fsdef_netfs_get_aux(const void *cookie_netfs_data, + void *buffer, uint16_t bufmax) +{ + const struct fscache_netfs *netfs = cookie_netfs_data; + unsigned dlen; + + _enter("{%s.%u},", netfs->name, netfs->version); + + dlen = sizeof(uint32_t); + if (dlen > bufmax) + return 0; + + memcpy(buffer, &netfs->version, dlen); + return dlen; +} + +/* + * check that the index structure version number stored in the auxiliary data + * matches the one the netfs gave us + */ +static enum fscache_checkaux fscache_fsdef_netfs_check_aux( + void *cookie_netfs_data, + const void *data, + uint16_t datalen) +{ + struct fscache_netfs *netfs = cookie_netfs_data; + uint32_t version; + + _enter("{%s},,%hu", netfs->name, datalen); + + if (datalen != sizeof(version)) { + _leave(" = OBSOLETE [dl=%d v=%zu]", datalen, sizeof(version)); + return FSCACHE_CHECKAUX_OBSOLETE; + } + + memcpy(&version, data, sizeof(version)); + if (version != netfs->version) { + _leave(" = OBSOLETE [ver=%x net=%x]", version, netfs->version); + return FSCACHE_CHECKAUX_OBSOLETE; + } + + _leave(" = OKAY"); + return FSCACHE_CHECKAUX_OKAY; +} diff --git a/fs/fscache/internal.h b/fs/fscache/internal.h index 16f9f1f46e4d..4113af8d1660 100644 --- a/fs/fscache/internal.h +++ b/fs/fscache/internal.h @@ -28,6 +28,12 @@ #define FSCACHE_MAX_THREADS 32 /* + * fsc-fsdef.c + */ +extern struct fscache_cookie fscache_fsdef_index; +extern struct fscache_cookie_def fscache_fsdef_netfs_def; + +/* * fsc-histogram.c */ #ifdef CONFIG_FSCACHE_HISTOGRAM |