target/linux/generic/files/fs/yaffs2/yaffs_packedtags2.c

   1 /*
   2  * YAFFS: Yet Another Flash File System. A NAND-flash specific file system.
   3  *
   4  * Copyright (C) 2002-2011 Aleph One Ltd.
   5  *   for Toby Churchill Ltd and Brightstar Engineering
   6  *
   7  * Created by Charles Manning <charles@aleph1.co.uk>
   8  *
   9  * This program is free software; you can redistribute it and/or modify
  10  * it under the terms of the GNU General Public License version 2 as
  11  * published by the Free Software Foundation.
  12  */
  13
  14 #include "yaffs_packedtags2.h"
  15 #include "yportenv.h"
  16 #include "yaffs_trace.h"
  17
  18 /* This code packs a set of extended tags into a binary structure for
  19  * NAND storage
  20  */
  21
  22 /* Some of the information is "extra" struff which can be packed in to
  23  * speed scanning
  24  * This is defined by having the EXTRA_HEADER_INFO_FLAG set.
  25  */
  26
  27 /* Extra flags applied to chunk_id */
  28
  29 #define EXTRA_HEADER_INFO_FLAG  0x80000000
  30 #define EXTRA_SHRINK_FLAG       0x40000000
  31 #define EXTRA_SHADOWS_FLAG      0x20000000
  32 #define EXTRA_SPARE_FLAGS       0x10000000
  33
  34 #define ALL_EXTRA_FLAGS         0xf0000000
  35
  36 /* Also, the top 4 bits of the object Id are set to the object type. */
  37 #define EXTRA_OBJECT_TYPE_SHIFT (28)
  38 #define EXTRA_OBJECT_TYPE_MASK  ((0x0f) << EXTRA_OBJECT_TYPE_SHIFT)
  39
  40 static void yaffs_dump_packed_tags2_tags_only(
  41                                 const struct yaffs_packed_tags2_tags_only *ptt)
  42 {
  43         yaffs_trace(YAFFS_TRACE_MTD,
  44                 "packed tags obj %d chunk %d byte %d seq %d",
  45                 ptt->obj_id, ptt->chunk_id, ptt->n_bytes, ptt->seq_number);
  46 }
  47
  48 static void yaffs_dump_packed_tags2(const struct yaffs_packed_tags2 *pt)
  49 {
  50         yaffs_dump_packed_tags2_tags_only(&pt->t);
  51 }
  52
  53 static void yaffs_dump_tags2(const struct yaffs_ext_tags *t)
  54 {
  55         yaffs_trace(YAFFS_TRACE_MTD,
  56                 "ext.tags eccres %d blkbad %d chused %d obj %d chunk%d byte %d del %d ser %d seq %d",
  57                 t->ecc_result, t->block_bad, t->chunk_used, t->obj_id,
  58                 t->chunk_id, t->n_bytes, t->is_deleted, t->serial_number,
  59                 t->seq_number);
  60
  61 }
  62
  63 static int yaffs_check_tags_extra_packable(const struct yaffs_ext_tags *t)
  64 {
  65         if (t->chunk_id != 0 || !t->extra_available)
  66                 return 0;
  67
  68         /* Check if the file size is too long to store */
  69         if (t->extra_obj_type == YAFFS_OBJECT_TYPE_FILE &&
  70             (t->extra_file_size >> 31) != 0)
  71                 return 0;
  72         return 1;
  73 }
  74
  75 void yaffs_pack_tags2_tags_only(struct yaffs_packed_tags2_tags_only *ptt,
  76                                 const struct yaffs_ext_tags *t)
  77 {
  78         ptt->chunk_id = t->chunk_id;
  79         ptt->seq_number = t->seq_number;
  80         ptt->n_bytes = t->n_bytes;
  81         ptt->obj_id = t->obj_id;
  82
  83         /* Only store extra tags for object headers.
  84          * If it is a file then only store  if the file size is short\
  85          * enough to fit.
  86          */
  87         if (yaffs_check_tags_extra_packable(t)) {
  88                 /* Store the extra header info instead */
  89                 /* We save the parent object in the chunk_id */
  90                 ptt->chunk_id = EXTRA_HEADER_INFO_FLAG | t->extra_parent_id;
  91                 if (t->extra_is_shrink)
  92                         ptt->chunk_id |= EXTRA_SHRINK_FLAG;
  93                 if (t->extra_shadows)
  94                         ptt->chunk_id |= EXTRA_SHADOWS_FLAG;
  95
  96                 ptt->obj_id &= ~EXTRA_OBJECT_TYPE_MASK;
  97                 ptt->obj_id |= (t->extra_obj_type << EXTRA_OBJECT_TYPE_SHIFT);
  98
  99                 if (t->extra_obj_type == YAFFS_OBJECT_TYPE_HARDLINK)
 100                         ptt->n_bytes = t->extra_equiv_id;
 101                 else if (t->extra_obj_type == YAFFS_OBJECT_TYPE_FILE)
 102                         ptt->n_bytes = (unsigned) t->extra_file_size;
 103                 else
 104                         ptt->n_bytes = 0;
 105         }
 106
 107         yaffs_dump_packed_tags2_tags_only(ptt);
 108         yaffs_dump_tags2(t);
 109 }
 110
 111 void yaffs_pack_tags2(struct yaffs_packed_tags2 *pt,
 112                       const struct yaffs_ext_tags *t, int tags_ecc)
 113 {
 114         yaffs_pack_tags2_tags_only(&pt->t, t);
 115
 116         if (tags_ecc)
 117                 yaffs_ecc_calc_other((unsigned char *)&pt->t,
 118                                     sizeof(struct yaffs_packed_tags2_tags_only),
 119                                     &pt->ecc);
 120 }
 121
 122 void yaffs_unpack_tags2_tags_only(struct yaffs_ext_tags *t,
 123                                   struct yaffs_packed_tags2_tags_only *ptt)
 124 {
 125         memset(t, 0, sizeof(struct yaffs_ext_tags));
 126
 127         if (ptt->seq_number == 0xffffffff)
 128                 return;
 129
 130         t->block_bad = 0;
 131         t->chunk_used = 1;
 132         t->obj_id = ptt->obj_id;
 133         t->chunk_id = ptt->chunk_id;
 134         t->n_bytes = ptt->n_bytes;
 135         t->is_deleted = 0;
 136         t->serial_number = 0;
 137         t->seq_number = ptt->seq_number;
 138
 139         /* Do extra header info stuff */
 140         if (ptt->chunk_id & EXTRA_HEADER_INFO_FLAG) {
 141                 t->chunk_id = 0;
 142                 t->n_bytes = 0;
 143
 144                 t->extra_available = 1;
 145                 t->extra_parent_id = ptt->chunk_id & (~(ALL_EXTRA_FLAGS));
 146                 t->extra_is_shrink = ptt->chunk_id & EXTRA_SHRINK_FLAG ? 1 : 0;
 147                 t->extra_shadows = ptt->chunk_id & EXTRA_SHADOWS_FLAG ? 1 : 0;
 148                 t->extra_obj_type = ptt->obj_id >> EXTRA_OBJECT_TYPE_SHIFT;
 149                 t->obj_id &= ~EXTRA_OBJECT_TYPE_MASK;
 150
 151                 if (t->extra_obj_type == YAFFS_OBJECT_TYPE_HARDLINK)
 152                         t->extra_equiv_id = ptt->n_bytes;
 153                 else
 154                         t->extra_file_size = ptt->n_bytes;
 155         }
 156         yaffs_dump_packed_tags2_tags_only(ptt);
 157         yaffs_dump_tags2(t);
 158 }
 159
 160 void yaffs_unpack_tags2(struct yaffs_ext_tags *t, struct yaffs_packed_tags2 *pt,
 161                         int tags_ecc)
 162 {
 163         enum yaffs_ecc_result ecc_result = YAFFS_ECC_RESULT_NO_ERROR;
 164
 165         if (pt->t.seq_number != 0xffffffff && tags_ecc) {
 166                 /* Chunk is in use and we need to do ECC */
 167
 168                 struct yaffs_ecc_other ecc;
 169                 int result;
 170                 yaffs_ecc_calc_other((unsigned char *)&pt->t,
 171                                 sizeof(struct yaffs_packed_tags2_tags_only),
 172                                 &ecc);
 173                 result =
 174                     yaffs_ecc_correct_other((unsigned char *)&pt->t,
 175                                 sizeof(struct yaffs_packed_tags2_tags_only),
 176                                 &pt->ecc, &ecc);
 177                 switch (result) {
 178                 case 0:
 179                         ecc_result = YAFFS_ECC_RESULT_NO_ERROR;
 180                         break;
 181                 case 1:
 182                         ecc_result = YAFFS_ECC_RESULT_FIXED;
 183                         break;
 184                 case -1:
 185                         ecc_result = YAFFS_ECC_RESULT_UNFIXED;
 186                         break;
 187                 default:
 188                         ecc_result = YAFFS_ECC_RESULT_UNKNOWN;
 189                 }
 190         }
 191         yaffs_unpack_tags2_tags_only(t, &pt->t);
 192
 193         t->ecc_result = ecc_result;
 194
 195         yaffs_dump_packed_tags2(pt);
 196         yaffs_dump_tags2(t);
 197 }