FS-Cache: Root index definition (a6891645) · Commits · 戴 / test

fs/fscache/Makefile

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		@@ -3,6 +3,7 @@
		#

		fscache-y := \
		fsdef.o \
		main.o

		fscache-$(CONFIG_PROC_FS) += proc.o

fs/fscache/fsdef.c

0 → 100644

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		/* 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;
		}

fs/fscache/internal.h

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		@@ -27,6 +27,12 @@
		#define FSCACHE_MIN_THREADS 4
		#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
		*/

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