~ [ source navigation ] ~ [ diff markup ] ~ [ identifier search ] ~

TOMOYO Linux Cross Reference
Linux/fs/efs/inode.c

Version: ~ [ linux-5.15-rc1 ] ~ [ linux-5.14.5 ] ~ [ linux-5.13.18 ] ~ [ linux-5.12.19 ] ~ [ linux-5.11.22 ] ~ [ linux-5.10.66 ] ~ [ linux-5.9.16 ] ~ [ linux-5.8.18 ] ~ [ linux-5.7.19 ] ~ [ linux-5.6.19 ] ~ [ linux-5.5.19 ] ~ [ linux-5.4.147 ] ~ [ linux-5.3.18 ] ~ [ linux-5.2.21 ] ~ [ linux-5.1.21 ] ~ [ linux-5.0.21 ] ~ [ linux-4.20.17 ] ~ [ linux-4.19.206 ] ~ [ linux-4.18.20 ] ~ [ linux-4.17.19 ] ~ [ linux-4.16.18 ] ~ [ linux-4.15.18 ] ~ [ linux-4.14.246 ] ~ [ linux-4.13.16 ] ~ [ linux-4.12.14 ] ~ [ linux-4.11.12 ] ~ [ linux-4.10.17 ] ~ [ linux-4.9.282 ] ~ [ linux-4.8.17 ] ~ [ linux-4.7.10 ] ~ [ linux-4.6.7 ] ~ [ linux-4.5.7 ] ~ [ linux-4.4.283 ] ~ [ linux-4.3.6 ] ~ [ linux-4.2.8 ] ~ [ linux-4.1.52 ] ~ [ linux-4.0.9 ] ~ [ linux-3.18.140 ] ~ [ linux-3.16.85 ] ~ [ linux-3.14.79 ] ~ [ linux-3.12.74 ] ~ [ linux-3.10.108 ] ~ [ linux-2.6.32.71 ] ~ [ linux-2.6.0 ] ~ [ linux-2.4.37.11 ] ~ [ unix-v6-master ] ~ [ ccs-tools-1.8.5 ] ~ [ policy-sample ] ~
Architecture: ~ [ i386 ] ~ [ alpha ] ~ [ m68k ] ~ [ mips ] ~ [ ppc ] ~ [ sparc ] ~ [ sparc64 ] ~

  1 // SPDX-License-Identifier: GPL-2.0-only
  2 /*
  3  * inode.c
  4  *
  5  * Copyright (c) 1999 Al Smith
  6  *
  7  * Portions derived from work (c) 1995,1996 Christian Vogelgsang,
  8  *              and from work (c) 1998 Mike Shaver.
  9  */
 10 
 11 #include <linux/buffer_head.h>
 12 #include <linux/module.h>
 13 #include <linux/fs.h>
 14 #include "efs.h"
 15 #include <linux/efs_fs_sb.h>
 16 
 17 static int efs_readpage(struct file *file, struct page *page)
 18 {
 19         return block_read_full_page(page,efs_get_block);
 20 }
 21 static sector_t _efs_bmap(struct address_space *mapping, sector_t block)
 22 {
 23         return generic_block_bmap(mapping,block,efs_get_block);
 24 }
 25 static const struct address_space_operations efs_aops = {
 26         .readpage = efs_readpage,
 27         .bmap = _efs_bmap
 28 };
 29 
 30 static inline void extent_copy(efs_extent *src, efs_extent *dst) {
 31         /*
 32          * this is slightly evil. it doesn't just copy
 33          * efs_extent from src to dst, it also mangles
 34          * the bits so that dst ends up in cpu byte-order.
 35          */
 36 
 37         dst->cooked.ex_magic  =  (unsigned int) src->raw[0];
 38         dst->cooked.ex_bn     = ((unsigned int) src->raw[1] << 16) |
 39                                 ((unsigned int) src->raw[2] <<  8) |
 40                                 ((unsigned int) src->raw[3] <<  0);
 41         dst->cooked.ex_length =  (unsigned int) src->raw[4];
 42         dst->cooked.ex_offset = ((unsigned int) src->raw[5] << 16) |
 43                                 ((unsigned int) src->raw[6] <<  8) |
 44                                 ((unsigned int) src->raw[7] <<  0);
 45         return;
 46 }
 47 
 48 struct inode *efs_iget(struct super_block *super, unsigned long ino)
 49 {
 50         int i, inode_index;
 51         dev_t device;
 52         u32 rdev;
 53         struct buffer_head *bh;
 54         struct efs_sb_info    *sb = SUPER_INFO(super);
 55         struct efs_inode_info *in;
 56         efs_block_t block, offset;
 57         struct efs_dinode *efs_inode;
 58         struct inode *inode;
 59 
 60         inode = iget_locked(super, ino);
 61         if (!inode)
 62                 return ERR_PTR(-ENOMEM);
 63         if (!(inode->i_state & I_NEW))
 64                 return inode;
 65 
 66         in = INODE_INFO(inode);
 67 
 68         /*
 69         ** EFS layout:
 70         **
 71         ** |   cylinder group    |   cylinder group    |   cylinder group ..etc
 72         ** |inodes|data          |inodes|data          |inodes|data       ..etc
 73         **
 74         ** work out the inode block index, (considering initially that the
 75         ** inodes are stored as consecutive blocks). then work out the block
 76         ** number of that inode given the above layout, and finally the
 77         ** offset of the inode within that block.
 78         */
 79 
 80         inode_index = inode->i_ino /
 81                 (EFS_BLOCKSIZE / sizeof(struct efs_dinode));
 82 
 83         block = sb->fs_start + sb->first_block + 
 84                 (sb->group_size * (inode_index / sb->inode_blocks)) +
 85                 (inode_index % sb->inode_blocks);
 86 
 87         offset = (inode->i_ino %
 88                         (EFS_BLOCKSIZE / sizeof(struct efs_dinode))) *
 89                 sizeof(struct efs_dinode);
 90 
 91         bh = sb_bread(inode->i_sb, block);
 92         if (!bh) {
 93                 pr_warn("%s() failed at block %d\n", __func__, block);
 94                 goto read_inode_error;
 95         }
 96 
 97         efs_inode = (struct efs_dinode *) (bh->b_data + offset);
 98     
 99         inode->i_mode  = be16_to_cpu(efs_inode->di_mode);
100         set_nlink(inode, be16_to_cpu(efs_inode->di_nlink));
101         i_uid_write(inode, (uid_t)be16_to_cpu(efs_inode->di_uid));
102         i_gid_write(inode, (gid_t)be16_to_cpu(efs_inode->di_gid));
103         inode->i_size  = be32_to_cpu(efs_inode->di_size);
104         inode->i_atime.tv_sec = be32_to_cpu(efs_inode->di_atime);
105         inode->i_mtime.tv_sec = be32_to_cpu(efs_inode->di_mtime);
106         inode->i_ctime.tv_sec = be32_to_cpu(efs_inode->di_ctime);
107         inode->i_atime.tv_nsec = inode->i_mtime.tv_nsec = inode->i_ctime.tv_nsec = 0;
108 
109         /* this is the number of blocks in the file */
110         if (inode->i_size == 0) {
111                 inode->i_blocks = 0;
112         } else {
113                 inode->i_blocks = ((inode->i_size - 1) >> EFS_BLOCKSIZE_BITS) + 1;
114         }
115 
116         rdev = be16_to_cpu(efs_inode->di_u.di_dev.odev);
117         if (rdev == 0xffff) {
118                 rdev = be32_to_cpu(efs_inode->di_u.di_dev.ndev);
119                 if (sysv_major(rdev) > 0xfff)
120                         device = 0;
121                 else
122                         device = MKDEV(sysv_major(rdev), sysv_minor(rdev));
123         } else
124                 device = old_decode_dev(rdev);
125 
126         /* get the number of extents for this object */
127         in->numextents = be16_to_cpu(efs_inode->di_numextents);
128         in->lastextent = 0;
129 
130         /* copy the extents contained within the inode to memory */
131         for(i = 0; i < EFS_DIRECTEXTENTS; i++) {
132                 extent_copy(&(efs_inode->di_u.di_extents[i]), &(in->extents[i]));
133                 if (i < in->numextents && in->extents[i].cooked.ex_magic != 0) {
134                         pr_warn("extent %d has bad magic number in inode %lu\n",
135                                 i, inode->i_ino);
136                         brelse(bh);
137                         goto read_inode_error;
138                 }
139         }
140 
141         brelse(bh);
142         pr_debug("efs_iget(): inode %lu, extents %d, mode %o\n",
143                  inode->i_ino, in->numextents, inode->i_mode);
144         switch (inode->i_mode & S_IFMT) {
145                 case S_IFDIR: 
146                         inode->i_op = &efs_dir_inode_operations; 
147                         inode->i_fop = &efs_dir_operations; 
148                         break;
149                 case S_IFREG:
150                         inode->i_fop = &generic_ro_fops;
151                         inode->i_data.a_ops = &efs_aops;
152                         break;
153                 case S_IFLNK:
154                         inode->i_op = &page_symlink_inode_operations;
155                         inode_nohighmem(inode);
156                         inode->i_data.a_ops = &efs_symlink_aops;
157                         break;
158                 case S_IFCHR:
159                 case S_IFBLK:
160                 case S_IFIFO:
161                         init_special_inode(inode, inode->i_mode, device);
162                         break;
163                 default:
164                         pr_warn("unsupported inode mode %o\n", inode->i_mode);
165                         goto read_inode_error;
166                         break;
167         }
168 
169         unlock_new_inode(inode);
170         return inode;
171         
172 read_inode_error:
173         pr_warn("failed to read inode %lu\n", inode->i_ino);
174         iget_failed(inode);
175         return ERR_PTR(-EIO);
176 }
177 
178 static inline efs_block_t
179 efs_extent_check(efs_extent *ptr, efs_block_t block, struct efs_sb_info *sb) {
180         efs_block_t start;
181         efs_block_t length;
182         efs_block_t offset;
183 
184         /*
185          * given an extent and a logical block within a file,
186          * can this block be found within this extent ?
187          */
188         start  = ptr->cooked.ex_bn;
189         length = ptr->cooked.ex_length;
190         offset = ptr->cooked.ex_offset;
191 
192         if ((block >= offset) && (block < offset+length)) {
193                 return(sb->fs_start + start + block - offset);
194         } else {
195                 return 0;
196         }
197 }
198 
199 efs_block_t efs_map_block(struct inode *inode, efs_block_t block) {
200         struct efs_sb_info    *sb = SUPER_INFO(inode->i_sb);
201         struct efs_inode_info *in = INODE_INFO(inode);
202         struct buffer_head    *bh = NULL;
203 
204         int cur, last, first = 1;
205         int ibase, ioffset, dirext, direxts, indext, indexts;
206         efs_block_t iblock, result = 0, lastblock = 0;
207         efs_extent ext, *exts;
208 
209         last = in->lastextent;
210 
211         if (in->numextents <= EFS_DIRECTEXTENTS) {
212                 /* first check the last extent we returned */
213                 if ((result = efs_extent_check(&in->extents[last], block, sb)))
214                         return result;
215     
216                 /* if we only have one extent then nothing can be found */
217                 if (in->numextents == 1) {
218                         pr_err("%s() failed to map (1 extent)\n", __func__);
219                         return 0;
220                 }
221 
222                 direxts = in->numextents;
223 
224                 /*
225                  * check the stored extents in the inode
226                  * start with next extent and check forwards
227                  */
228                 for(dirext = 1; dirext < direxts; dirext++) {
229                         cur = (last + dirext) % in->numextents;
230                         if ((result = efs_extent_check(&in->extents[cur], block, sb))) {
231                                 in->lastextent = cur;
232                                 return result;
233                         }
234                 }
235 
236                 pr_err("%s() failed to map block %u (dir)\n", __func__, block);
237                 return 0;
238         }
239 
240         pr_debug("%s(): indirect search for logical block %u\n",
241                  __func__, block);
242         direxts = in->extents[0].cooked.ex_offset;
243         indexts = in->numextents;
244 
245         for(indext = 0; indext < indexts; indext++) {
246                 cur = (last + indext) % indexts;
247 
248                 /*
249                  * work out which direct extent contains `cur'.
250                  *
251                  * also compute ibase: i.e. the number of the first
252                  * indirect extent contained within direct extent `cur'.
253                  *
254                  */
255                 ibase = 0;
256                 for(dirext = 0; cur < ibase && dirext < direxts; dirext++) {
257                         ibase += in->extents[dirext].cooked.ex_length *
258                                 (EFS_BLOCKSIZE / sizeof(efs_extent));
259                 }
260 
261                 if (dirext == direxts) {
262                         /* should never happen */
263                         pr_err("couldn't find direct extent for indirect extent %d (block %u)\n",
264                                cur, block);
265                         if (bh) brelse(bh);
266                         return 0;
267                 }
268                 
269                 /* work out block number and offset of this indirect extent */
270                 iblock = sb->fs_start + in->extents[dirext].cooked.ex_bn +
271                         (cur - ibase) /
272                         (EFS_BLOCKSIZE / sizeof(efs_extent));
273                 ioffset = (cur - ibase) %
274                         (EFS_BLOCKSIZE / sizeof(efs_extent));
275 
276                 if (first || lastblock != iblock) {
277                         if (bh) brelse(bh);
278 
279                         bh = sb_bread(inode->i_sb, iblock);
280                         if (!bh) {
281                                 pr_err("%s() failed at block %d\n",
282                                        __func__, iblock);
283                                 return 0;
284                         }
285                         pr_debug("%s(): read indirect extent block %d\n",
286                                  __func__, iblock);
287                         first = 0;
288                         lastblock = iblock;
289                 }
290 
291                 exts = (efs_extent *) bh->b_data;
292 
293                 extent_copy(&(exts[ioffset]), &ext);
294 
295                 if (ext.cooked.ex_magic != 0) {
296                         pr_err("extent %d has bad magic number in block %d\n",
297                                cur, iblock);
298                         if (bh) brelse(bh);
299                         return 0;
300                 }
301 
302                 if ((result = efs_extent_check(&ext, block, sb))) {
303                         if (bh) brelse(bh);
304                         in->lastextent = cur;
305                         return result;
306                 }
307         }
308         if (bh) brelse(bh);
309         pr_err("%s() failed to map block %u (indir)\n", __func__, block);
310         return 0;
311 }  
312 
313 MODULE_LICENSE("GPL");
314 

~ [ source navigation ] ~ [ diff markup ] ~ [ identifier search ] ~

kernel.org | git.kernel.org | LWN.net | Project Home | Wiki (Japanese) | Wiki (English) | SVN repository | Mail admin

Linux® is a registered trademark of Linus Torvalds in the United States and other countries.
TOMOYO® is a registered trademark of NTT DATA CORPORATION.

osdn.jp