linux/fs/ntfs/lcnalloc.h
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   1/*
   2 * lcnalloc.h - Exports for NTFS kernel cluster (de)allocation.  Part of the
   3 *              Linux-NTFS project.
   4 *
   5 * Copyright (c) 2004-2005 Anton Altaparmakov
   6 *
   7 * This program/include file is free software; you can redistribute it and/or
   8 * modify it under the terms of the GNU General Public License as published
   9 * by the Free Software Foundation; either version 2 of the License, or
  10 * (at your option) any later version.
  11 *
  12 * This program/include file is distributed in the hope that it will be
  13 * useful, but WITHOUT ANY WARRANTY; without even the implied warranty
  14 * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15 * GNU General Public License for more details.
  16 *
  17 * You should have received a copy of the GNU General Public License
  18 * along with this program (in the main directory of the Linux-NTFS
  19 * distribution in the file COPYING); if not, write to the Free Software
  20 * Foundation,Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  21 */
  22
  23#ifndef _LINUX_NTFS_LCNALLOC_H
  24#define _LINUX_NTFS_LCNALLOC_H
  25
  26#ifdef NTFS_RW
  27
  28#include <linux/fs.h>
  29
  30#include "attrib.h"
  31#include "types.h"
  32#include "inode.h"
  33#include "runlist.h"
  34#include "volume.h"
  35
  36typedef enum {
  37        FIRST_ZONE      = 0,    /* For sanity checking. */
  38        MFT_ZONE        = 0,    /* Allocate from $MFT zone. */
  39        DATA_ZONE       = 1,    /* Allocate from $DATA zone. */
  40        LAST_ZONE       = 1,    /* For sanity checking. */
  41} NTFS_CLUSTER_ALLOCATION_ZONES;
  42
  43extern runlist_element *ntfs_cluster_alloc(ntfs_volume *vol,
  44                const VCN start_vcn, const s64 count, const LCN start_lcn,
  45                const NTFS_CLUSTER_ALLOCATION_ZONES zone,
  46                const bool is_extension);
  47
  48extern s64 __ntfs_cluster_free(ntfs_inode *ni, const VCN start_vcn,
  49                s64 count, ntfs_attr_search_ctx *ctx, const bool is_rollback);
  50
  51/**
  52 * ntfs_cluster_free - free clusters on an ntfs volume
  53 * @ni:         ntfs inode whose runlist describes the clusters to free
  54 * @start_vcn:  vcn in the runlist of @ni at which to start freeing clusters
  55 * @count:      number of clusters to free or -1 for all clusters
  56 * @ctx:        active attribute search context if present or NULL if not
  57 *
  58 * Free @count clusters starting at the cluster @start_vcn in the runlist
  59 * described by the ntfs inode @ni.
  60 *
  61 * If @count is -1, all clusters from @start_vcn to the end of the runlist are
  62 * deallocated.  Thus, to completely free all clusters in a runlist, use
  63 * @start_vcn = 0 and @count = -1.
  64 *
  65 * If @ctx is specified, it is an active search context of @ni and its base mft
  66 * record.  This is needed when ntfs_cluster_free() encounters unmapped runlist
  67 * fragments and allows their mapping.  If you do not have the mft record
  68 * mapped, you can specify @ctx as NULL and ntfs_cluster_free() will perform
  69 * the necessary mapping and unmapping.
  70 *
  71 * Note, ntfs_cluster_free() saves the state of @ctx on entry and restores it
  72 * before returning.  Thus, @ctx will be left pointing to the same attribute on
  73 * return as on entry.  However, the actual pointers in @ctx may point to
  74 * different memory locations on return, so you must remember to reset any
  75 * cached pointers from the @ctx, i.e. after the call to ntfs_cluster_free(),
  76 * you will probably want to do:
  77 *      m = ctx->mrec;
  78 *      a = ctx->attr;
  79 * Assuming you cache ctx->attr in a variable @a of type ATTR_RECORD * and that
  80 * you cache ctx->mrec in a variable @m of type MFT_RECORD *.
  81 *
  82 * Note, ntfs_cluster_free() does not modify the runlist, so you have to remove
  83 * from the runlist or mark sparse the freed runs later.
  84 *
  85 * Return the number of deallocated clusters (not counting sparse ones) on
  86 * success and -errno on error.
  87 *
  88 * WARNING: If @ctx is supplied, regardless of whether success or failure is
  89 *          returned, you need to check IS_ERR(@ctx->mrec) and if 'true' the @ctx
  90 *          is no longer valid, i.e. you need to either call
  91 *          ntfs_attr_reinit_search_ctx() or ntfs_attr_put_search_ctx() on it.
  92 *          In that case PTR_ERR(@ctx->mrec) will give you the error code for
  93 *          why the mapping of the old inode failed.
  94 *
  95 * Locking: - The runlist described by @ni must be locked for writing on entry
  96 *            and is locked on return.  Note the runlist may be modified when
  97 *            needed runlist fragments need to be mapped.
  98 *          - The volume lcn bitmap must be unlocked on entry and is unlocked
  99 *            on return.
 100 *          - This function takes the volume lcn bitmap lock for writing and
 101 *            modifies the bitmap contents.
 102 *          - If @ctx is NULL, the base mft record of @ni must not be mapped on
 103 *            entry and it will be left unmapped on return.
 104 *          - If @ctx is not NULL, the base mft record must be mapped on entry
 105 *            and it will be left mapped on return.
 106 */
 107static inline s64 ntfs_cluster_free(ntfs_inode *ni, const VCN start_vcn,
 108                s64 count, ntfs_attr_search_ctx *ctx)
 109{
 110        return __ntfs_cluster_free(ni, start_vcn, count, ctx, false);
 111}
 112
 113extern int ntfs_cluster_free_from_rl_nolock(ntfs_volume *vol,
 114                const runlist_element *rl);
 115
 116/**
 117 * ntfs_cluster_free_from_rl - free clusters from runlist
 118 * @vol:        mounted ntfs volume on which to free the clusters
 119 * @rl:         runlist describing the clusters to free
 120 *
 121 * Free all the clusters described by the runlist @rl on the volume @vol.  In
 122 * the case of an error being returned, at least some of the clusters were not
 123 * freed.
 124 *
 125 * Return 0 on success and -errno on error.
 126 *
 127 * Locking: - This function takes the volume lcn bitmap lock for writing and
 128 *            modifies the bitmap contents.
 129 *          - The caller must have locked the runlist @rl for reading or
 130 *            writing.
 131 */
 132static inline int ntfs_cluster_free_from_rl(ntfs_volume *vol,
 133                const runlist_element *rl)
 134{
 135        int ret;
 136
 137        down_write(&vol->lcnbmp_lock);
 138        ret = ntfs_cluster_free_from_rl_nolock(vol, rl);
 139        up_write(&vol->lcnbmp_lock);
 140        return ret;
 141}
 142
 143#endif /* NTFS_RW */
 144
 145#endif /* defined _LINUX_NTFS_LCNALLOC_H */
 146
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