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Linux/fs/adfs/inode.c

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  1 /*
  2  *  linux/fs/adfs/inode.c
  3  *
  4  *  Copyright (C) 1997-1999 Russell King
  5  *
  6  * This program is free software; you can redistribute it and/or modify
  7  * it under the terms of the GNU General Public License version 2 as
  8  * published by the Free Software Foundation.
  9  */
 10 #include <linux/smp_lock.h>
 11 #include <linux/buffer_head.h>
 12 #include "adfs.h"
 13 
 14 /*
 15  * Lookup/Create a block at offset 'block' into 'inode'.  We currently do
 16  * not support creation of new blocks, so we return -EIO for this case.
 17  */
 18 static int
 19 adfs_get_block(struct inode *inode, sector_t block, struct buffer_head *bh,
 20                int create)
 21 {
 22         if (!create) {
 23                 if (block >= inode->i_blocks)
 24                         goto abort_toobig;
 25 
 26                 block = __adfs_block_map(inode->i_sb, inode->i_ino, block);
 27                 if (block)
 28                         map_bh(bh, inode->i_sb, block);
 29                 return 0;
 30         }
 31         /* don't support allocation of blocks yet */
 32         return -EIO;
 33 
 34 abort_toobig:
 35         return 0;
 36 }
 37 
 38 static int adfs_writepage(struct page *page, struct writeback_control *wbc)
 39 {
 40         return block_write_full_page(page, adfs_get_block, wbc);
 41 }
 42 
 43 static int adfs_readpage(struct file *file, struct page *page)
 44 {
 45         return block_read_full_page(page, adfs_get_block);
 46 }
 47 
 48 static int adfs_write_begin(struct file *file, struct address_space *mapping,
 49                         loff_t pos, unsigned len, unsigned flags,
 50                         struct page **pagep, void **fsdata)
 51 {
 52         *pagep = NULL;
 53         return cont_write_begin(file, mapping, pos, len, flags, pagep, fsdata,
 54                                 adfs_get_block,
 55                                 &ADFS_I(mapping->host)->mmu_private);
 56 }
 57 
 58 static sector_t _adfs_bmap(struct address_space *mapping, sector_t block)
 59 {
 60         return generic_block_bmap(mapping, block, adfs_get_block);
 61 }
 62 
 63 static const struct address_space_operations adfs_aops = {
 64         .readpage       = adfs_readpage,
 65         .writepage      = adfs_writepage,
 66         .sync_page      = block_sync_page,
 67         .write_begin    = adfs_write_begin,
 68         .write_end      = generic_write_end,
 69         .bmap           = _adfs_bmap
 70 };
 71 
 72 static inline unsigned int
 73 adfs_filetype(struct inode *inode)
 74 {
 75         unsigned int type;
 76 
 77         if (ADFS_I(inode)->stamped)
 78                 type = (ADFS_I(inode)->loadaddr >> 8) & 0xfff;
 79         else
 80                 type = (unsigned int) -1;
 81 
 82         return type;
 83 }
 84 
 85 /*
 86  * Convert ADFS attributes and filetype to Linux permission.
 87  */
 88 static umode_t
 89 adfs_atts2mode(struct super_block *sb, struct inode *inode)
 90 {
 91         unsigned int filetype, attr = ADFS_I(inode)->attr;
 92         umode_t mode, rmask;
 93         struct adfs_sb_info *asb = ADFS_SB(sb);
 94 
 95         if (attr & ADFS_NDA_DIRECTORY) {
 96                 mode = S_IRUGO & asb->s_owner_mask;
 97                 return S_IFDIR | S_IXUGO | mode;
 98         }
 99 
100         filetype = adfs_filetype(inode);
101 
102         switch (filetype) {
103         case 0xfc0:     /* LinkFS */
104                 return S_IFLNK|S_IRWXUGO;
105 
106         case 0xfe6:     /* UnixExec */
107                 rmask = S_IRUGO | S_IXUGO;
108                 break;
109 
110         default:
111                 rmask = S_IRUGO;
112         }
113 
114         mode = S_IFREG;
115 
116         if (attr & ADFS_NDA_OWNER_READ)
117                 mode |= rmask & asb->s_owner_mask;
118 
119         if (attr & ADFS_NDA_OWNER_WRITE)
120                 mode |= S_IWUGO & asb->s_owner_mask;
121 
122         if (attr & ADFS_NDA_PUBLIC_READ)
123                 mode |= rmask & asb->s_other_mask;
124 
125         if (attr & ADFS_NDA_PUBLIC_WRITE)
126                 mode |= S_IWUGO & asb->s_other_mask;
127         return mode;
128 }
129 
130 /*
131  * Convert Linux permission to ADFS attribute.  We try to do the reverse
132  * of atts2mode, but there is not a 1:1 translation.
133  */
134 static int
135 adfs_mode2atts(struct super_block *sb, struct inode *inode)
136 {
137         umode_t mode;
138         int attr;
139         struct adfs_sb_info *asb = ADFS_SB(sb);
140 
141         /* FIXME: should we be able to alter a link? */
142         if (S_ISLNK(inode->i_mode))
143                 return ADFS_I(inode)->attr;
144 
145         if (S_ISDIR(inode->i_mode))
146                 attr = ADFS_NDA_DIRECTORY;
147         else
148                 attr = 0;
149 
150         mode = inode->i_mode & asb->s_owner_mask;
151         if (mode & S_IRUGO)
152                 attr |= ADFS_NDA_OWNER_READ;
153         if (mode & S_IWUGO)
154                 attr |= ADFS_NDA_OWNER_WRITE;
155 
156         mode = inode->i_mode & asb->s_other_mask;
157         mode &= ~asb->s_owner_mask;
158         if (mode & S_IRUGO)
159                 attr |= ADFS_NDA_PUBLIC_READ;
160         if (mode & S_IWUGO)
161                 attr |= ADFS_NDA_PUBLIC_WRITE;
162 
163         return attr;
164 }
165 
166 /*
167  * Convert an ADFS time to Unix time.  ADFS has a 40-bit centi-second time
168  * referenced to 1 Jan 1900 (til 2248)
169  */
170 static void
171 adfs_adfs2unix_time(struct timespec *tv, struct inode *inode)
172 {
173         unsigned int high, low;
174 
175         if (ADFS_I(inode)->stamped == 0)
176                 goto cur_time;
177 
178         high = ADFS_I(inode)->loadaddr << 24;
179         low  = ADFS_I(inode)->execaddr;
180 
181         high |= low >> 8;
182         low  &= 255;
183 
184         /* Files dated pre  01 Jan 1970 00:00:00. */
185         if (high < 0x336e996a)
186                 goto too_early;
187 
188         /* Files dated post 18 Jan 2038 03:14:05. */
189         if (high >= 0x656e9969)
190                 goto too_late;
191 
192         /* discard 2208988800 (0x336e996a00) seconds of time */
193         high -= 0x336e996a;
194 
195         /* convert 40-bit centi-seconds to 32-bit seconds */
196         tv->tv_sec = (((high % 100) << 8) + low) / 100 + (high / 100 << 8);
197         tv->tv_nsec = 0;
198         return;
199 
200  cur_time:
201         *tv = CURRENT_TIME_SEC;
202         return;
203 
204  too_early:
205         tv->tv_sec = tv->tv_nsec = 0;
206         return;
207 
208  too_late:
209         tv->tv_sec = 0x7ffffffd;
210         tv->tv_nsec = 0;
211         return;
212 }
213 
214 /*
215  * Convert an Unix time to ADFS time.  We only do this if the entry has a
216  * time/date stamp already.
217  */
218 static void
219 adfs_unix2adfs_time(struct inode *inode, unsigned int secs)
220 {
221         unsigned int high, low;
222 
223         if (ADFS_I(inode)->stamped) {
224                 /* convert 32-bit seconds to 40-bit centi-seconds */
225                 low  = (secs & 255) * 100;
226                 high = (secs / 256) * 100 + (low >> 8) + 0x336e996a;
227 
228                 ADFS_I(inode)->loadaddr = (high >> 24) |
229                                 (ADFS_I(inode)->loadaddr & ~0xff);
230                 ADFS_I(inode)->execaddr = (low & 255) | (high << 8);
231         }
232 }
233 
234 /*
235  * Fill in the inode information from the object information.
236  *
237  * Note that this is an inode-less filesystem, so we can't use the inode
238  * number to reference the metadata on the media.  Instead, we use the
239  * inode number to hold the object ID, which in turn will tell us where
240  * the data is held.  We also save the parent object ID, and with these
241  * two, we can locate the metadata.
242  *
243  * This does mean that we rely on an objects parent remaining the same at
244  * all times - we cannot cope with a cross-directory rename (yet).
245  */
246 struct inode *
247 adfs_iget(struct super_block *sb, struct object_info *obj)
248 {
249         struct inode *inode;
250 
251         inode = new_inode(sb);
252         if (!inode)
253                 goto out;
254 
255         inode->i_uid     = ADFS_SB(sb)->s_uid;
256         inode->i_gid     = ADFS_SB(sb)->s_gid;
257         inode->i_ino     = obj->file_id;
258         inode->i_size    = obj->size;
259         inode->i_nlink   = 2;
260         inode->i_blocks  = (inode->i_size + sb->s_blocksize - 1) >>
261                             sb->s_blocksize_bits;
262 
263         /*
264          * we need to save the parent directory ID so that
265          * write_inode can update the directory information
266          * for this file.  This will need special handling
267          * for cross-directory renames.
268          */
269         ADFS_I(inode)->parent_id = obj->parent_id;
270         ADFS_I(inode)->loadaddr  = obj->loadaddr;
271         ADFS_I(inode)->execaddr  = obj->execaddr;
272         ADFS_I(inode)->attr      = obj->attr;
273         ADFS_I(inode)->stamped    = ((obj->loadaddr & 0xfff00000) == 0xfff00000);
274 
275         inode->i_mode    = adfs_atts2mode(sb, inode);
276         adfs_adfs2unix_time(&inode->i_mtime, inode);
277         inode->i_atime = inode->i_mtime;
278         inode->i_ctime = inode->i_mtime;
279 
280         if (S_ISDIR(inode->i_mode)) {
281                 inode->i_op     = &adfs_dir_inode_operations;
282                 inode->i_fop    = &adfs_dir_operations;
283         } else if (S_ISREG(inode->i_mode)) {
284                 inode->i_op     = &adfs_file_inode_operations;
285                 inode->i_fop    = &adfs_file_operations;
286                 inode->i_mapping->a_ops = &adfs_aops;
287                 ADFS_I(inode)->mmu_private = inode->i_size;
288         }
289 
290         insert_inode_hash(inode);
291 
292 out:
293         return inode;
294 }
295 
296 /*
297  * Validate and convert a changed access mode/time to their ADFS equivalents.
298  * adfs_write_inode will actually write the information back to the directory
299  * later.
300  */
301 int
302 adfs_notify_change(struct dentry *dentry, struct iattr *attr)
303 {
304         struct inode *inode = dentry->d_inode;
305         struct super_block *sb = inode->i_sb;
306         unsigned int ia_valid = attr->ia_valid;
307         int error;
308         
309         lock_kernel();
310 
311         error = inode_change_ok(inode, attr);
312 
313         /*
314          * we can't change the UID or GID of any file -
315          * we have a global UID/GID in the superblock
316          */
317         if ((ia_valid & ATTR_UID && attr->ia_uid != ADFS_SB(sb)->s_uid) ||
318             (ia_valid & ATTR_GID && attr->ia_gid != ADFS_SB(sb)->s_gid))
319                 error = -EPERM;
320 
321         if (error)
322                 goto out;
323 
324         if (ia_valid & ATTR_SIZE)
325                 error = vmtruncate(inode, attr->ia_size);
326 
327         if (error)
328                 goto out;
329 
330         if (ia_valid & ATTR_MTIME) {
331                 inode->i_mtime = attr->ia_mtime;
332                 adfs_unix2adfs_time(inode, attr->ia_mtime.tv_sec);
333         }
334         /*
335          * FIXME: should we make these == to i_mtime since we don't
336          * have the ability to represent them in our filesystem?
337          */
338         if (ia_valid & ATTR_ATIME)
339                 inode->i_atime = attr->ia_atime;
340         if (ia_valid & ATTR_CTIME)
341                 inode->i_ctime = attr->ia_ctime;
342         if (ia_valid & ATTR_MODE) {
343                 ADFS_I(inode)->attr = adfs_mode2atts(sb, inode);
344                 inode->i_mode = adfs_atts2mode(sb, inode);
345         }
346 
347         /*
348          * FIXME: should we be marking this inode dirty even if
349          * we don't have any metadata to write back?
350          */
351         if (ia_valid & (ATTR_SIZE | ATTR_MTIME | ATTR_MODE))
352                 mark_inode_dirty(inode);
353 out:
354         unlock_kernel();
355         return error;
356 }
357 
358 /*
359  * write an existing inode back to the directory, and therefore the disk.
360  * The adfs-specific inode data has already been updated by
361  * adfs_notify_change()
362  */
363 int adfs_write_inode(struct inode *inode, int wait)
364 {
365         struct super_block *sb = inode->i_sb;
366         struct object_info obj;
367         int ret;
368 
369         lock_kernel();
370         obj.file_id     = inode->i_ino;
371         obj.name_len    = 0;
372         obj.parent_id   = ADFS_I(inode)->parent_id;
373         obj.loadaddr    = ADFS_I(inode)->loadaddr;
374         obj.execaddr    = ADFS_I(inode)->execaddr;
375         obj.attr        = ADFS_I(inode)->attr;
376         obj.size        = inode->i_size;
377 
378         ret = adfs_dir_update(sb, &obj, wait);
379         unlock_kernel();
380         return ret;
381 }
382 

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