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* Copyright (C) 2000 Richard Guenther
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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#ifndef _SWFS_CLUSTER_H
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#define _SWFS_CLUSTER_H
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#include "swfs_ctree.h"
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/* Cluster instance, flags are
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* SWC_DIRTY - files list is dirty
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* SWC_CREAT - the data file needs to be created
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* SWC_NOT_IN_CORE - files_cnt and files is uninitialized */
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#define SWC_NOT_IN_CORE 4
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/* Fields protected by the global CLUSTERS lock.
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struct swcluster *next_swcluster_hash;
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struct swcluster **pprev_swcluster_hash;
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struct glame_list_head lru;
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int usage; /* number of references to this struct cluster */
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/* All fields below are protected by the CLUSTER lock
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* (which is nonexistent at the moment - FIXME).
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int flags; /* SWC_* */
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/* The size field is always initialized. */
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s32 size; /* size of the cluster */
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/* The fd is not always open - check for it (-1 if not).
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* Clusters with open files are in the fdlru list. */
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struct glame_list_head fdlru;
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int fd; /* cached fd of the on-disk _data_ */
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/* Fields created out of the cluster metadata, if
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* SWC_NOT_IN_CORE is set, none of this fields is initialized. */
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int files_cnt; /* number of files that use this cluster */
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long *files; /* list of files that use this cluster */
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/* Cluster shared mapping:
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* - if map_addr is NULL, no mapping is there and other fields
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* need to be PROT_NONE, 0
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* - map_prot is protection of the mapping (can be PROT_NONE)
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* - map_cnt is the number of references to the mapping */
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/* Hash is read-protected by the CLUSTER lock, write protected
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* by the global MAPPINGS lock. */
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struct swcluster *next_mapping_hash;
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struct swcluster **pprev_mapping_hash;
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struct glame_list_head maplru;
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/* A maximum size goal we want to achieve for this inefficient
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* implementation via a native filesystem - else it would be S32_MAX. */
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#define SWCLUSTER_MAXSIZE (256*1024)
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/* Initialize the cluster subsystem. Maxlru is the maximum number of
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* cluster descriptors cached in memory, maxfds the maximum number
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* of files kept open, maxmaps the maximum number of inactive memory
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* maps to cache and maxvm a goal for the maximum amount of virtual
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* memory used by the cluster mappings. */
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static int cluster_init(int maxlru, int maxfds,
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int maxmaps, size_t maxvm);
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/* Cleanup from the cluster subsystem. */
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static void cluster_cleanup();
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/* Gets a reference to the specified cluster, if CLUSTERGET_READFILES
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* is set, the list of files that use this cluster is read in. Returns
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* a reference or NULL on error. You may specify the size of the cluster
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* data, if you know it to speed up an eventual readin of the cluster,
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* specify -1, if you dont known the size. */
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#define CLUSTERGET_READFILES 1
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static struct swcluster *cluster_get(long name, int flags, s32 known_size);
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/* Releases the reference, if CLUSTERPUT_SYNC is set, the list of
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* files that use this cluster is synced back to disk. */
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#define CLUSTERPUT_SYNC 1
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#define CLUSTERPUT_FREE 2
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static void cluster_put(struct swcluster *c, int flags);
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/* Allocates a new cluster with room for size bytes of data.
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* Returns a cluster reference on success, NULL on failure. */
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static struct swcluster *cluster_alloc(s32 size);
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/* Adds the specified file to the list of users of this cluster. */
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static void cluster_addfileref(struct swcluster *c, long file);
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/* Deletes the specified file from the list of users of this
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* cluster. Returns 0 if this was succesful and -1 if there
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* was no such user file. */
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static int cluster_delfileref(struct swcluster *c, long file);
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/* Checks, if the cluster has a reference on the file file. Returns
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* 0 if that is the case, else -1. */
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static int cluster_checkfileref(struct swcluster *c, long file);
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/* Creates a memory map of the cluster c possibly at address
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* start with protection and flags like mmap(2). */
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static char *cluster_mmap(struct swcluster *c, int prot, int flags);
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/* Unmaps a previously mmapped cluster. Returns 0 on success
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* and -1 on error (invalid supplied address) */
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static int cluster_munmap(char *start);
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/* Read data like read(2). Offset is cluster internal. */
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static ssize_t cluster_read(struct swcluster *c, void *buf,
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size_t count, off_t offset);
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/* Write data like write(2). Offset is cluster internal. */
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static ssize_t cluster_write(struct swcluster *c, const void *buf,
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size_t count, off_t offset);
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/* Splits the cluster c at position offset storing the head inside
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* ch and the tail after omitting cutcnt bytes after offset inside ct.
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* The head cluster may be identical to c afterwards, if there was only
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* one user of c, but two references are returned. This operation is
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* able to throw away (truncate) the resulting head/tail, if ch or
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static void cluster_split(struct swcluster *c, s32 offset, s32 cutcnt,
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struct swcluster **ch, struct swcluster **ct);
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/* Truncates the cluster to the specified size, if the cluster is not
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* shared and returns 0, else (shared cluster) -1 is returned. */
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static int cluster_truncate(struct swcluster *c, s32 size);
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/* Copy the cluster, if it is shared, else return the original cluster. */
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static struct swcluster *cluster_unshare(struct swcluster *c);
added
removed
src/swapfile/swfs_cluster.h
