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fs/fscache/fsdef.c
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// SPDX-License-Identifier: GPL-2.0-or-later |
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/* Filesystem index definition * * Copyright (C) 2004-2007 Red Hat, Inc. All Rights Reserved. * Written by David Howells (dhowells@redhat.com) |
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*/ #define FSCACHE_DEBUG_LEVEL CACHE #include <linux/module.h> #include "internal.h" |
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static enum fscache_checkaux fscache_fsdef_netfs_check_aux(void *cookie_netfs_data, const void *data, |
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uint16_t datalen, loff_t object_size); |
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/* * 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), |
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.n_active = ATOMIC_INIT(1), |
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.lock = __SPIN_LOCK_UNLOCKED(fscache_fsdef_index.lock), .backing_objects = HLIST_HEAD_INIT, .def = &fscache_fsdef_index_def, |
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.flags = 1 << FSCACHE_COOKIE_ENABLED, |
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.type = FSCACHE_COOKIE_TYPE_INDEX, |
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}; 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, |
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.check_aux = fscache_fsdef_netfs_check_aux, }; /* |
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* 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, |
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uint16_t datalen, loff_t object_size) |
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{ 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; } |