The Design and Implementation of the FreeBSD Operating System, Second Edition
Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)


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FreeBSD/Linux Kernel Cross Reference
sys/fs/udf/truncate.c

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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/buffer_head.h>
   26 
   27 #include "udf_i.h"
   28 #include "udf_sb.h"
   29 
   30 static void extent_trunc(struct inode *inode, struct extent_position *epos,
   31                          struct kernel_lb_addr *eloc, int8_t etype, uint32_t elen,
   32                          uint32_t nelen)
   33 {
   34         struct kernel_lb_addr neloc = {};
   35         int last_block = (elen + inode->i_sb->s_blocksize - 1) >>
   36                 inode->i_sb->s_blocksize_bits;
   37         int first_block = (nelen + inode->i_sb->s_blocksize - 1) >>
   38                 inode->i_sb->s_blocksize_bits;
   39 
   40         if (nelen) {
   41                 if (etype == (EXT_NOT_RECORDED_ALLOCATED >> 30)) {
   42                         udf_free_blocks(inode->i_sb, inode, eloc, 0,
   43                                         last_block);
   44                         etype = (EXT_NOT_RECORDED_NOT_ALLOCATED >> 30);
   45                 } else
   46                         neloc = *eloc;
   47                 nelen = (etype << 30) | nelen;
   48         }
   49 
   50         if (elen != nelen) {
   51                 udf_write_aext(inode, epos, &neloc, nelen, 0);
   52                 if (last_block - first_block > 0) {
   53                         if (etype == (EXT_RECORDED_ALLOCATED >> 30))
   54                                 mark_inode_dirty(inode);
   55 
   56                         if (etype != (EXT_NOT_RECORDED_NOT_ALLOCATED >> 30))
   57                                 udf_free_blocks(inode->i_sb, inode, eloc,
   58                                                 first_block,
   59                                                 last_block - first_block);
   60                 }
   61         }
   62 }
   63 
   64 /*
   65  * Truncate the last extent to match i_size. This function assumes
   66  * that preallocation extent is already truncated.
   67  */
   68 void udf_truncate_tail_extent(struct inode *inode)
   69 {
   70         struct extent_position epos = {};
   71         struct kernel_lb_addr eloc;
   72         uint32_t elen, nelen;
   73         uint64_t lbcount = 0;
   74         int8_t etype = -1, netype;
   75         int adsize;
   76         struct udf_inode_info *iinfo = UDF_I(inode);
   77 
   78         if (iinfo->i_alloc_type == ICBTAG_FLAG_AD_IN_ICB ||
   79             inode->i_size == iinfo->i_lenExtents)
   80                 return;
   81         /* Are we going to delete the file anyway? */
   82         if (inode->i_nlink == 0)
   83                 return;
   84 
   85         if (iinfo->i_alloc_type == ICBTAG_FLAG_AD_SHORT)
   86                 adsize = sizeof(struct short_ad);
   87         else if (iinfo->i_alloc_type == ICBTAG_FLAG_AD_LONG)
   88                 adsize = sizeof(struct long_ad);
   89         else
   90                 BUG();
   91 
   92         /* Find the last extent in the file */
   93         while ((netype = udf_next_aext(inode, &epos, &eloc, &elen, 1)) != -1) {
   94                 etype = netype;
   95                 lbcount += elen;
   96                 if (lbcount > inode->i_size) {
   97                         if (lbcount - inode->i_size >= inode->i_sb->s_blocksize)
   98                                 udf_warn(inode->i_sb,
   99                                          "Too long extent after EOF in inode %u: i_size: %lld lbcount: %lld extent %u+%u\n",
  100                                          (unsigned)inode->i_ino,
  101                                          (long long)inode->i_size,
  102                                          (long long)lbcount,
  103                                          (unsigned)eloc.logicalBlockNum,
  104                                          (unsigned)elen);
  105                         nelen = elen - (lbcount - inode->i_size);
  106                         epos.offset -= adsize;
  107                         extent_trunc(inode, &epos, &eloc, etype, elen, nelen);
  108                         epos.offset += adsize;
  109                         if (udf_next_aext(inode, &epos, &eloc, &elen, 1) != -1)
  110                                 udf_err(inode->i_sb,
  111                                         "Extent after EOF in inode %u\n",
  112                                         (unsigned)inode->i_ino);
  113                         break;
  114                 }
  115         }
  116         /* This inode entry is in-memory only and thus we don't have to mark
  117          * the inode dirty */
  118         iinfo->i_lenExtents = inode->i_size;
  119         brelse(epos.bh);
  120 }
  121 
  122 void udf_discard_prealloc(struct inode *inode)
  123 {
  124         struct extent_position epos = { NULL, 0, {0, 0} };
  125         struct kernel_lb_addr eloc;
  126         uint32_t elen;
  127         uint64_t lbcount = 0;
  128         int8_t etype = -1, netype;
  129         int adsize;
  130         struct udf_inode_info *iinfo = UDF_I(inode);
  131 
  132         if (iinfo->i_alloc_type == ICBTAG_FLAG_AD_IN_ICB ||
  133             inode->i_size == iinfo->i_lenExtents)
  134                 return;
  135 
  136         if (iinfo->i_alloc_type == ICBTAG_FLAG_AD_SHORT)
  137                 adsize = sizeof(struct short_ad);
  138         else if (iinfo->i_alloc_type == ICBTAG_FLAG_AD_LONG)
  139                 adsize = sizeof(struct long_ad);
  140         else
  141                 adsize = 0;
  142 
  143         epos.block = iinfo->i_location;
  144 
  145         /* Find the last extent in the file */
  146         while ((netype = udf_next_aext(inode, &epos, &eloc, &elen, 1)) != -1) {
  147                 etype = netype;
  148                 lbcount += elen;
  149         }
  150         if (etype == (EXT_NOT_RECORDED_ALLOCATED >> 30)) {
  151                 epos.offset -= adsize;
  152                 lbcount -= elen;
  153                 extent_trunc(inode, &epos, &eloc, etype, elen, 0);
  154                 if (!epos.bh) {
  155                         iinfo->i_lenAlloc =
  156                                 epos.offset -
  157                                 udf_file_entry_alloc_offset(inode);
  158                         mark_inode_dirty(inode);
  159                 } else {
  160                         struct allocExtDesc *aed =
  161                                 (struct allocExtDesc *)(epos.bh->b_data);
  162                         aed->lengthAllocDescs =
  163                                 cpu_to_le32(epos.offset -
  164                                             sizeof(struct allocExtDesc));
  165                         if (!UDF_QUERY_FLAG(inode->i_sb, UDF_FLAG_STRICT) ||
  166                             UDF_SB(inode->i_sb)->s_udfrev >= 0x0201)
  167                                 udf_update_tag(epos.bh->b_data, epos.offset);
  168                         else
  169                                 udf_update_tag(epos.bh->b_data,
  170                                                sizeof(struct allocExtDesc));
  171                         mark_buffer_dirty_inode(epos.bh, inode);
  172                 }
  173         }
  174         /* This inode entry is in-memory only and thus we don't have to mark
  175          * the inode dirty */
  176         iinfo->i_lenExtents = lbcount;
  177         brelse(epos.bh);
  178 }
  179 
  180 static void udf_update_alloc_ext_desc(struct inode *inode,
  181                                       struct extent_position *epos,
  182                                       u32 lenalloc)
  183 {
  184         struct super_block *sb = inode->i_sb;
  185         struct udf_sb_info *sbi = UDF_SB(sb);
  186 
  187         struct allocExtDesc *aed = (struct allocExtDesc *) (epos->bh->b_data);
  188         int len = sizeof(struct allocExtDesc);
  189 
  190         aed->lengthAllocDescs = cpu_to_le32(lenalloc);
  191         if (!UDF_QUERY_FLAG(sb, UDF_FLAG_STRICT) || sbi->s_udfrev >= 0x0201)
  192                 len += lenalloc;
  193 
  194         udf_update_tag(epos->bh->b_data, len);
  195         mark_buffer_dirty_inode(epos->bh, inode);
  196 }
  197 
  198 /*
  199  * Truncate extents of inode to inode->i_size. This function can be used only
  200  * for making file shorter. For making file longer, udf_extend_file() has to
  201  * be used.
  202  */
  203 void udf_truncate_extents(struct inode *inode)
  204 {
  205         struct extent_position epos;
  206         struct kernel_lb_addr eloc, neloc = {};
  207         uint32_t elen, nelen = 0, indirect_ext_len = 0, lenalloc;
  208         int8_t etype;
  209         struct super_block *sb = inode->i_sb;
  210         sector_t first_block = inode->i_size >> sb->s_blocksize_bits, offset;
  211         loff_t byte_offset;
  212         int adsize;
  213         struct udf_inode_info *iinfo = UDF_I(inode);
  214 
  215         if (iinfo->i_alloc_type == ICBTAG_FLAG_AD_SHORT)
  216                 adsize = sizeof(struct short_ad);
  217         else if (iinfo->i_alloc_type == ICBTAG_FLAG_AD_LONG)
  218                 adsize = sizeof(struct long_ad);
  219         else
  220                 BUG();
  221 
  222         etype = inode_bmap(inode, first_block, &epos, &eloc, &elen, &offset);
  223         byte_offset = (offset << sb->s_blocksize_bits) +
  224                 (inode->i_size & (sb->s_blocksize - 1));
  225         if (etype == -1) {
  226                 /* We should extend the file? */
  227                 WARN_ON(byte_offset);
  228                 return;
  229         }
  230         epos.offset -= adsize;
  231         extent_trunc(inode, &epos, &eloc, etype, elen, byte_offset);
  232         epos.offset += adsize;
  233         if (byte_offset)
  234                 lenalloc = epos.offset;
  235         else
  236                 lenalloc = epos.offset - adsize;
  237 
  238         if (!epos.bh)
  239                 lenalloc -= udf_file_entry_alloc_offset(inode);
  240         else
  241                 lenalloc -= sizeof(struct allocExtDesc);
  242 
  243         while ((etype = udf_current_aext(inode, &epos, &eloc,
  244                                          &elen, 0)) != -1) {
  245                 if (etype == (EXT_NEXT_EXTENT_ALLOCDECS >> 30)) {
  246                         udf_write_aext(inode, &epos, &neloc, nelen, 0);
  247                         if (indirect_ext_len) {
  248                                 /* We managed to free all extents in the
  249                                  * indirect extent - free it too */
  250                                 BUG_ON(!epos.bh);
  251                                 udf_free_blocks(sb, NULL, &epos.block,
  252                                                 0, indirect_ext_len);
  253                         } else if (!epos.bh) {
  254                                 iinfo->i_lenAlloc = lenalloc;
  255                                 mark_inode_dirty(inode);
  256                         } else
  257                                 udf_update_alloc_ext_desc(inode,
  258                                                 &epos, lenalloc);
  259                         brelse(epos.bh);
  260                         epos.offset = sizeof(struct allocExtDesc);
  261                         epos.block = eloc;
  262                         epos.bh = udf_tread(sb,
  263                                         udf_get_lb_pblock(sb, &eloc, 0));
  264                         if (elen)
  265                                 indirect_ext_len =
  266                                         (elen + sb->s_blocksize - 1) >>
  267                                         sb->s_blocksize_bits;
  268                         else
  269                                 indirect_ext_len = 1;
  270                 } else {
  271                         extent_trunc(inode, &epos, &eloc, etype, elen, 0);
  272                         epos.offset += adsize;
  273                 }
  274         }
  275 
  276         if (indirect_ext_len) {
  277                 BUG_ON(!epos.bh);
  278                 udf_free_blocks(sb, NULL, &epos.block, 0, indirect_ext_len);
  279         } else if (!epos.bh) {
  280                 iinfo->i_lenAlloc = lenalloc;
  281                 mark_inode_dirty(inode);
  282         } else
  283                 udf_update_alloc_ext_desc(inode, &epos, lenalloc);
  284         iinfo->i_lenExtents = inode->i_size;
  285 
  286         brelse(epos.bh);
  287 }

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