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   1 /*
   2  * truncate.c
   3  *
   4  * PURPOSE
   5  *      Truncate handling routines for the OSTA-UDF(tm) filesystem.
   6  *
   7  * COPYRIGHT
   8  *      This file is distributed under the terms of the GNU General Public
   9  *      License (GPL). Copies of the GPL can be obtained from:
  10  *              ftp://prep.ai.mit.edu/pub/gnu/GPL
  11  *      Each contributing author retains all rights to their own work.
  12  *
  13  *  (C) 1999-2004 Ben Fennema
  14  *  (C) 1999 Stelias Computing Inc
  15  *
  16  * HISTORY
  17  *
  18  *  02/24/99 blf  Created.
  19  *
  20  */
  21
  22 #include "udfdecl.h"
  23 #include <linux/fs.h>
  24 #include <linux/mm.h>
  25 #include <linux/udf_fs.h>
  26 #include <linux/buffer_head.h>
  27
  28 #include "udf_i.h"
  29 #include "udf_sb.h"
  30
  31 static void extent_trunc(struct inode * inode, struct extent_position *epos,
  32         kernel_lb_addr eloc, int8_t etype, uint32_t elen, uint32_t nelen)
  33 {
  34         kernel_lb_addr neloc = { 0, 0 };
  35         int last_block = (elen + inode->i_sb->s_blocksize - 1) >> inode->i_sb->s_blocksize_bits;
  36         int first_block = (nelen + inode->i_sb->s_blocksize - 1) >> inode->i_sb->s_blocksize_bits;
  37
  38         if (nelen)
  39         {
  40                 if (etype == (EXT_NOT_RECORDED_ALLOCATED >> 30))
  41                 {
  42                         udf_free_blocks(inode->i_sb, inode, eloc, 0, last_block);
  43                         etype = (EXT_NOT_RECORDED_NOT_ALLOCATED >> 30);
  44                 }
  45                 else
  46                         neloc = eloc;
  47                 nelen = (etype << 30) | nelen;
  48         }
  49
  50         if (elen != nelen)
  51         {
  52                 udf_write_aext(inode, epos, neloc, nelen, 0);
  53                 if (last_block - first_block > 0)
  54                 {
  55                         if (etype == (EXT_RECORDED_ALLOCATED >> 30))
  56                                 mark_inode_dirty(inode);
  57
  58                         if (etype != (EXT_NOT_RECORDED_NOT_ALLOCATED >> 30))
  59                                 udf_free_blocks(inode->i_sb, inode, eloc, first_block, last_block - first_block);
  60                 }
  61         }
  62 }
  63
  64 void udf_discard_prealloc(struct inode * inode)
  65 {
  66         struct extent_position epos = { NULL, 0, {0, 0}};
  67         kernel_lb_addr eloc;
  68         uint32_t elen, nelen;
  69         uint64_t lbcount = 0;
  70         int8_t etype = -1, netype;
  71         int adsize;
  72
  73         if (UDF_I_ALLOCTYPE(inode) == ICBTAG_FLAG_AD_IN_ICB ||
  74                 inode->i_size == UDF_I_LENEXTENTS(inode))
  75                 return;
  76
  77         if (UDF_I_ALLOCTYPE(inode) == ICBTAG_FLAG_AD_SHORT)
  78                 adsize = sizeof(short_ad);
  79         else if (UDF_I_ALLOCTYPE(inode) == ICBTAG_FLAG_AD_LONG)
  80                 adsize = sizeof(long_ad);
  81         else
  82                 adsize = 0;
  83
  84         epos.block = UDF_I_LOCATION(inode);
  85
  86         /* Find the last extent in the file */
  87         while ((netype = udf_next_aext(inode, &epos, &eloc, &elen, 1)) != -1)
  88         {
  89                 etype = netype;
  90                 lbcount += elen;
  91                 if (lbcount > inode->i_size && lbcount - elen < inode->i_size)
  92                 {
  93                         WARN_ON(lbcount - inode->i_size >= inode->i_sb->s_blocksize);
  94                         nelen = elen - (lbcount - inode->i_size);
  95                         epos.offset -= adsize;
  96                         extent_trunc(inode, &epos, eloc, etype, elen, nelen);
  97                         epos.offset += adsize;
  98                         lbcount = inode->i_size;
  99                 }
 100         }
 101         if (etype == (EXT_NOT_RECORDED_ALLOCATED >> 30)) {
 102                 epos.offset -= adsize;
 103                 lbcount -= elen;
 104                 extent_trunc(inode, &epos, eloc, etype, elen, 0);
 105                 if (!epos.bh)
 106                 {
 107                         UDF_I_LENALLOC(inode) = epos.offset - udf_file_entry_alloc_offset(inode);
 108                         mark_inode_dirty(inode);
 109                 }
 110                 else
 111                 {
 112                         struct allocExtDesc *aed = (struct allocExtDesc *)(epos.bh->b_data);
 113                         aed->lengthAllocDescs = cpu_to_le32(epos.offset - sizeof(struct allocExtDesc));
 114                         if (!UDF_QUERY_FLAG(inode->i_sb, UDF_FLAG_STRICT) || UDF_SB_UDFREV(inode->i_sb) >= 0x0201)
 115                                 udf_update_tag(epos.bh->b_data, epos.offset);
 116                         else
 117                                 udf_update_tag(epos.bh->b_data, sizeof(struct allocExtDesc));
 118                         mark_buffer_dirty_inode(epos.bh, inode);
 119                 }
 120         }
 121         UDF_I_LENEXTENTS(inode) = lbcount;
 122
 123         WARN_ON(lbcount != inode->i_size);
 124         brelse(epos.bh);
 125 }
 126
 127 void udf_truncate_extents(struct inode * inode)
 128 {
 129         struct extent_position epos;
 130         kernel_lb_addr eloc, neloc = { 0, 0 };
 131         uint32_t elen, nelen = 0, indirect_ext_len = 0, lenalloc;
 132         int8_t etype;
 133         struct super_block *sb = inode->i_sb;
 134         sector_t first_block = inode->i_size >> sb->s_blocksize_bits, offset;
 135         loff_t byte_offset;
 136         int adsize;
 137
 138         if (UDF_I_ALLOCTYPE(inode) == ICBTAG_FLAG_AD_SHORT)
 139                 adsize = sizeof(short_ad);
 140         else if (UDF_I_ALLOCTYPE(inode) == ICBTAG_FLAG_AD_LONG)
 141                 adsize = sizeof(long_ad);
 142         else
 143                 BUG();
 144
 145         etype = inode_bmap(inode, first_block, &epos, &eloc, &elen, &offset);
 146         byte_offset = (offset << sb->s_blocksize_bits) + (inode->i_size & (sb->s_blocksize-1));
 147         if (etype != -1)
 148         {
 149                 epos.offset -= adsize;
 150                 extent_trunc(inode, &epos, eloc, etype, elen, byte_offset);
 151                 epos.offset += adsize;
 152                 if (byte_offset)
 153                         lenalloc = epos.offset;
 154                 else
 155                         lenalloc = epos.offset - adsize;
 156
 157                 if (!epos.bh)
 158                         lenalloc -= udf_file_entry_alloc_offset(inode);
 159                 else
 160                         lenalloc -= sizeof(struct allocExtDesc);
 161
 162                 while ((etype = udf_current_aext(inode, &epos, &eloc, &elen, 0)) != -1)
 163                 {
 164                         if (etype == (EXT_NEXT_EXTENT_ALLOCDECS >> 30))
 165                         {
 166                                 udf_write_aext(inode, &epos, neloc, nelen, 0);
 167                                 if (indirect_ext_len)
 168                                 {
 169                                         /* We managed to free all extents in the
 170                                          * indirect extent - free it too */
 171                                         if (!epos.bh)
 172                                                 BUG();
 173                                         udf_free_blocks(sb, inode, epos.block, 0, indirect_ext_len);
 174                                 }
 175                                 else
 176                                 {
 177                                         if (!epos.bh)
 178                                         {
 179                                                 UDF_I_LENALLOC(inode) = lenalloc;
 180                                                 mark_inode_dirty(inode);
 181                                         }
 182                                         else
 183                                         {
 184                                                 struct allocExtDesc *aed = (struct allocExtDesc *)(epos.bh->b_data);
 185                                                 aed->lengthAllocDescs = cpu_to_le32(lenalloc);
 186                                                 if (!UDF_QUERY_FLAG(sb, UDF_FLAG_STRICT) || UDF_SB_UDFREV(sb) >= 0x0201)
 187                                                         udf_update_tag(epos.bh->b_data, lenalloc +
 188                                                                 sizeof(struct allocExtDesc));
 189                                                 else
 190                                                         udf_update_tag(epos.bh->b_data, sizeof(struct allocExtDesc));
 191                                                 mark_buffer_dirty_inode(epos.bh, inode);
 192                                         }
 193                                 }
 194                                 brelse(epos.bh);
 195                                 epos.offset = sizeof(struct allocExtDesc);
 196                                 epos.block = eloc;
 197                                 epos.bh = udf_tread(sb, udf_get_lb_pblock(sb, eloc, 0));
 198                                 if (elen)
 199                                         indirect_ext_len = (elen +
 200                                                 sb->s_blocksize - 1) >>
 201                                                 sb->s_blocksize_bits;
 202                                 else
 203                                         indirect_ext_len = 1;
 204                         }
 205                         else
 206                         {
 207                                 extent_trunc(inode, &epos, eloc, etype, elen, 0);
 208                                 epos.offset += adsize;
 209                         }
 210                 }
 211
 212                 if (indirect_ext_len)
 213                 {
 214                         if (!epos.bh)
 215                                 BUG();
 216                         udf_free_blocks(sb, inode, epos.block, 0, indirect_ext_len);
 217                 }
 218                 else
 219                 {
 220                         if (!epos.bh)
 221                         {
 222                                 UDF_I_LENALLOC(inode) = lenalloc;
 223                                 mark_inode_dirty(inode);
 224                         }
 225                         else
 226                         {
 227                                 struct allocExtDesc *aed = (struct allocExtDesc *)(epos.bh->b_data);
 228                                 aed->lengthAllocDescs = cpu_to_le32(lenalloc);
 229                                 if (!UDF_QUERY_FLAG(sb, UDF_FLAG_STRICT) || UDF_SB_UDFREV(sb) >= 0x0201)
 230                                         udf_update_tag(epos.bh->b_data, lenalloc +
 231                                                 sizeof(struct allocExtDesc));
 232                                 else
 233                                         udf_update_tag(epos.bh->b_data, sizeof(struct allocExtDesc));
 234                                 mark_buffer_dirty_inode(epos.bh, inode);
 235                         }
 236                 }
 237         }
 238         else if (inode->i_size)
 239         {
 240                 if (byte_offset)
 241                 {
 242                         kernel_long_ad extent;
 243
 244                         /*
 245                          *  OK, there is not extent covering inode->i_size and
 246                          *  no extent above inode->i_size => truncate is
 247                          *  extending the file by 'offset' blocks.
 248                          */
 249                         if ((!epos.bh && epos.offset == udf_file_entry_alloc_offset(inode)) ||
 250                             (epos.bh && epos.offset == sizeof(struct allocExtDesc))) {
 251                                 /* File has no extents at all or has empty last
 252                                  * indirect extent! Create a fake extent... */
 253                                 extent.extLocation.logicalBlockNum = 0;
 254                                 extent.extLocation.partitionReferenceNum = 0;
 255                                 extent.extLength = EXT_NOT_RECORDED_NOT_ALLOCATED;
 256                         }
 257                         else {
 258                                 epos.offset -= adsize;
 259                                 etype = udf_next_aext(inode, &epos,
 260                                         &extent.extLocation, &extent.extLength, 0);
 261                                 extent.extLength |= etype << 30;
 262                         }
 263                         udf_extend_file(inode, &epos, &extent, offset+((inode->i_size & (sb->s_blocksize-1)) != 0));
 264                 }
 265         }
 266         UDF_I_LENEXTENTS(inode) = inode->i_size;
 267
 268         brelse(epos.bh);
 269 }