fs/ntfs/lcnalloc.h

   1 /* SPDX-License-Identifier: GPL-2.0-or-later */
   2 /*
   3  * lcnalloc.h - Exports for NTFS kernel cluster (de)allocation.  Part of the
   4  *              Linux-NTFS project.
   5  *
   6  * Copyright (c) 2004-2005 Anton Altaparmakov
   7  */
   8
   9 #ifndef _LINUX_NTFS_LCNALLOC_H
  10 #define _LINUX_NTFS_LCNALLOC_H
  11
  12 #ifdef NTFS_RW
  13
  14 #include <linux/fs.h>
  15
  16 #include "attrib.h"
  17 #include "types.h"
  18 #include "inode.h"
  19 #include "runlist.h"
  20 #include "volume.h"
  21
  22 typedef enum {
  23         FIRST_ZONE      = 0,    /* For sanity checking. */
  24         MFT_ZONE        = 0,    /* Allocate from $MFT zone. */
  25         DATA_ZONE       = 1,    /* Allocate from $DATA zone. */
  26         LAST_ZONE       = 1,    /* For sanity checking. */
  27 } NTFS_CLUSTER_ALLOCATION_ZONES;
  28
  29 extern runlist_element *ntfs_cluster_alloc(ntfs_volume *vol,
  30                 const VCN start_vcn, const s64 count, const LCN start_lcn,
  31                 const NTFS_CLUSTER_ALLOCATION_ZONES zone,
  32                 const bool is_extension);
  33
  34 extern s64 __ntfs_cluster_free(ntfs_inode *ni, const VCN start_vcn,
  35                 s64 count, ntfs_attr_search_ctx *ctx, const bool is_rollback);
  36
  37 /**
  38  * ntfs_cluster_free - free clusters on an ntfs volume
  39  * @ni:         ntfs inode whose runlist describes the clusters to free
  40  * @start_vcn:  vcn in the runlist of @ni at which to start freeing clusters
  41  * @count:      number of clusters to free or -1 for all clusters
  42  * @ctx:        active attribute search context if present or NULL if not
  43  *
  44  * Free @count clusters starting at the cluster @start_vcn in the runlist
  45  * described by the ntfs inode @ni.
  46  *
  47  * If @count is -1, all clusters from @start_vcn to the end of the runlist are
  48  * deallocated.  Thus, to completely free all clusters in a runlist, use
  49  * @start_vcn = 0 and @count = -1.
  50  *
  51  * If @ctx is specified, it is an active search context of @ni and its base mft
  52  * record.  This is needed when ntfs_cluster_free() encounters unmapped runlist
  53  * fragments and allows their mapping.  If you do not have the mft record
  54  * mapped, you can specify @ctx as NULL and ntfs_cluster_free() will perform
  55  * the necessary mapping and unmapping.
  56  *
  57  * Note, ntfs_cluster_free() saves the state of @ctx on entry and restores it
  58  * before returning.  Thus, @ctx will be left pointing to the same attribute on
  59  * return as on entry.  However, the actual pointers in @ctx may point to
  60  * different memory locations on return, so you must remember to reset any
  61  * cached pointers from the @ctx, i.e. after the call to ntfs_cluster_free(),
  62  * you will probably want to do:
  63  *      m = ctx->mrec;
  64  *      a = ctx->attr;
  65  * Assuming you cache ctx->attr in a variable @a of type ATTR_RECORD * and that
  66  * you cache ctx->mrec in a variable @m of type MFT_RECORD *.
  67  *
  68  * Note, ntfs_cluster_free() does not modify the runlist, so you have to remove
  69  * from the runlist or mark sparse the freed runs later.
  70  *
  71  * Return the number of deallocated clusters (not counting sparse ones) on
  72  * success and -errno on error.
  73  *
  74  * WARNING: If @ctx is supplied, regardless of whether success or failure is
  75  *          returned, you need to check IS_ERR(@ctx->mrec) and if 'true' the @ctx
  76  *          is no longer valid, i.e. you need to either call
  77  *          ntfs_attr_reinit_search_ctx() or ntfs_attr_put_search_ctx() on it.
  78  *          In that case PTR_ERR(@ctx->mrec) will give you the error code for
  79  *          why the mapping of the old inode failed.
  80  *
  81  * Locking: - The runlist described by @ni must be locked for writing on entry
  82  *            and is locked on return.  Note the runlist may be modified when
  83  *            needed runlist fragments need to be mapped.
  84  *          - The volume lcn bitmap must be unlocked on entry and is unlocked
  85  *            on return.
  86  *          - This function takes the volume lcn bitmap lock for writing and
  87  *            modifies the bitmap contents.
  88  *          - If @ctx is NULL, the base mft record of @ni must not be mapped on
  89  *            entry and it will be left unmapped on return.
  90  *          - If @ctx is not NULL, the base mft record must be mapped on entry
  91  *            and it will be left mapped on return.
  92  */
  93 static inline s64 ntfs_cluster_free(ntfs_inode *ni, const VCN start_vcn,
  94                 s64 count, ntfs_attr_search_ctx *ctx)
  95 {
  96         return __ntfs_cluster_free(ni, start_vcn, count, ctx, false);
  97 }
  98
  99 extern int ntfs_cluster_free_from_rl_nolock(ntfs_volume *vol,
 100                 const runlist_element *rl);
 101
 102 /**
 103  * ntfs_cluster_free_from_rl - free clusters from runlist
 104  * @vol:        mounted ntfs volume on which to free the clusters
 105  * @rl:         runlist describing the clusters to free
 106  *
 107  * Free all the clusters described by the runlist @rl on the volume @vol.  In
 108  * the case of an error being returned, at least some of the clusters were not
 109  * freed.
 110  *
 111  * Return 0 on success and -errno on error.
 112  *
 113  * Locking: - This function takes the volume lcn bitmap lock for writing and
 114  *            modifies the bitmap contents.
 115  *          - The caller must have locked the runlist @rl for reading or
 116  *            writing.
 117  */
 118 static inline int ntfs_cluster_free_from_rl(ntfs_volume *vol,
 119                 const runlist_element *rl)
 120 {
 121         int ret;
 122
 123         down_write(&vol->lcnbmp_lock);
 124         ret = ntfs_cluster_free_from_rl_nolock(vol, rl);
 125         up_write(&vol->lcnbmp_lock);
 126         return ret;
 127 }
 128
 129 #endif /* NTFS_RW */
 130
 131 #endif /* defined _LINUX_NTFS_LCNALLOC_H */