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Linux/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, inode, &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, inode, &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 }
288 

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