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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/buffer_head.h>
 11 #include <linux/writeback.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 void adfs_write_failed(struct address_space *mapping, loff_t to)
 49 {
 50         struct inode *inode = mapping->host;
 51 
 52         if (to > inode->i_size)
 53                 truncate_pagecache(inode, inode->i_size);
 54 }
 55 
 56 static int adfs_write_begin(struct file *file, struct address_space *mapping,
 57                         loff_t pos, unsigned len, unsigned flags,
 58                         struct page **pagep, void **fsdata)
 59 {
 60         int ret;
 61 
 62         *pagep = NULL;
 63         ret = cont_write_begin(file, mapping, pos, len, flags, pagep, fsdata,
 64                                 adfs_get_block,
 65                                 &ADFS_I(mapping->host)->mmu_private);
 66         if (unlikely(ret))
 67                 adfs_write_failed(mapping, pos + len);
 68 
 69         return ret;
 70 }
 71 
 72 static sector_t _adfs_bmap(struct address_space *mapping, sector_t block)
 73 {
 74         return generic_block_bmap(mapping, block, adfs_get_block);
 75 }
 76 
 77 static const struct address_space_operations adfs_aops = {
 78         .readpage       = adfs_readpage,
 79         .writepage      = adfs_writepage,
 80         .write_begin    = adfs_write_begin,
 81         .write_end      = generic_write_end,
 82         .bmap           = _adfs_bmap
 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 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         switch (ADFS_I(inode)->filetype) {
101         case 0xfc0:     /* LinkFS */
102                 return S_IFLNK|S_IRWXUGO;
103 
104         case 0xfe6:     /* UnixExec */
105                 rmask = S_IRUGO | S_IXUGO;
106                 break;
107 
108         default:
109                 rmask = S_IRUGO;
110         }
111 
112         mode = S_IFREG;
113 
114         if (attr & ADFS_NDA_OWNER_READ)
115                 mode |= rmask & asb->s_owner_mask;
116 
117         if (attr & ADFS_NDA_OWNER_WRITE)
118                 mode |= S_IWUGO & asb->s_owner_mask;
119 
120         if (attr & ADFS_NDA_PUBLIC_READ)
121                 mode |= rmask & asb->s_other_mask;
122 
123         if (attr & ADFS_NDA_PUBLIC_WRITE)
124                 mode |= S_IWUGO & asb->s_other_mask;
125         return mode;
126 }
127 
128 /*
129  * Convert Linux permission to ADFS attribute.  We try to do the reverse
130  * of atts2mode, but there is not a 1:1 translation.
131  */
132 static int
133 adfs_mode2atts(struct super_block *sb, struct inode *inode)
134 {
135         umode_t mode;
136         int attr;
137         struct adfs_sb_info *asb = ADFS_SB(sb);
138 
139         /* FIXME: should we be able to alter a link? */
140         if (S_ISLNK(inode->i_mode))
141                 return ADFS_I(inode)->attr;
142 
143         if (S_ISDIR(inode->i_mode))
144                 attr = ADFS_NDA_DIRECTORY;
145         else
146                 attr = 0;
147 
148         mode = inode->i_mode & asb->s_owner_mask;
149         if (mode & S_IRUGO)
150                 attr |= ADFS_NDA_OWNER_READ;
151         if (mode & S_IWUGO)
152                 attr |= ADFS_NDA_OWNER_WRITE;
153 
154         mode = inode->i_mode & asb->s_other_mask;
155         mode &= ~asb->s_owner_mask;
156         if (mode & S_IRUGO)
157                 attr |= ADFS_NDA_PUBLIC_READ;
158         if (mode & S_IWUGO)
159                 attr |= ADFS_NDA_PUBLIC_WRITE;
160 
161         return attr;
162 }
163 
164 /*
165  * Convert an ADFS time to Unix time.  ADFS has a 40-bit centi-second time
166  * referenced to 1 Jan 1900 (til 2248) so we need to discard 2208988800 seconds
167  * of time to convert from RISC OS epoch to Unix epoch.
168  */
169 static void
170 adfs_adfs2unix_time(struct timespec *tv, struct inode *inode)
171 {
172         unsigned int high, low;
173         /* 01 Jan 1970 00:00:00 (Unix epoch) as nanoseconds since
174          * 01 Jan 1900 00:00:00 (RISC OS epoch)
175          */
176         static const s64 nsec_unix_epoch_diff_risc_os_epoch =
177                                                         2208988800000000000LL;
178         s64 nsec;
179 
180         if (ADFS_I(inode)->stamped == 0)
181                 goto cur_time;
182 
183         high = ADFS_I(inode)->loadaddr & 0xFF; /* top 8 bits of timestamp */
184         low  = ADFS_I(inode)->execaddr;    /* bottom 32 bits of timestamp */
185 
186         /* convert 40-bit centi-seconds to 32-bit seconds
187          * going via nanoseconds to retain precision
188          */
189         nsec = (((s64) high << 32) | (s64) low) * 10000000; /* cs to ns */
190 
191         /* Files dated pre  01 Jan 1970 00:00:00. */
192         if (nsec < nsec_unix_epoch_diff_risc_os_epoch)
193                 goto too_early;
194 
195         /* convert from RISC OS to Unix epoch */
196         nsec -= nsec_unix_epoch_diff_risc_os_epoch;
197 
198         *tv = ns_to_timespec(nsec);
199         return;
200 
201  cur_time:
202         *tv = CURRENT_TIME;
203         return;
204 
205  too_early:
206         tv->tv_sec = tv->tv_nsec = 0;
207         return;
208 }
209 
210 /*
211  * Convert an Unix time to ADFS time.  We only do this if the entry has a
212  * time/date stamp already.
213  */
214 static void
215 adfs_unix2adfs_time(struct inode *inode, unsigned int secs)
216 {
217         unsigned int high, low;
218 
219         if (ADFS_I(inode)->stamped) {
220                 /* convert 32-bit seconds to 40-bit centi-seconds */
221                 low  = (secs & 255) * 100;
222                 high = (secs / 256) * 100 + (low >> 8) + 0x336e996a;
223 
224                 ADFS_I(inode)->loadaddr = (high >> 24) |
225                                 (ADFS_I(inode)->loadaddr & ~0xff);
226                 ADFS_I(inode)->execaddr = (low & 255) | (high << 8);
227         }
228 }
229 
230 /*
231  * Fill in the inode information from the object information.
232  *
233  * Note that this is an inode-less filesystem, so we can't use the inode
234  * number to reference the metadata on the media.  Instead, we use the
235  * inode number to hold the object ID, which in turn will tell us where
236  * the data is held.  We also save the parent object ID, and with these
237  * two, we can locate the metadata.
238  *
239  * This does mean that we rely on an objects parent remaining the same at
240  * all times - we cannot cope with a cross-directory rename (yet).
241  */
242 struct inode *
243 adfs_iget(struct super_block *sb, struct object_info *obj)
244 {
245         struct inode *inode;
246 
247         inode = new_inode(sb);
248         if (!inode)
249                 goto out;
250 
251         inode->i_uid     = ADFS_SB(sb)->s_uid;
252         inode->i_gid     = ADFS_SB(sb)->s_gid;
253         inode->i_ino     = obj->file_id;
254         inode->i_size    = obj->size;
255         set_nlink(inode, 2);
256         inode->i_blocks  = (inode->i_size + sb->s_blocksize - 1) >>
257                             sb->s_blocksize_bits;
258 
259         /*
260          * we need to save the parent directory ID so that
261          * write_inode can update the directory information
262          * for this file.  This will need special handling
263          * for cross-directory renames.
264          */
265         ADFS_I(inode)->parent_id = obj->parent_id;
266         ADFS_I(inode)->loadaddr  = obj->loadaddr;
267         ADFS_I(inode)->execaddr  = obj->execaddr;
268         ADFS_I(inode)->attr      = obj->attr;
269         ADFS_I(inode)->filetype  = obj->filetype;
270         ADFS_I(inode)->stamped   = ((obj->loadaddr & 0xfff00000) == 0xfff00000);
271 
272         inode->i_mode    = adfs_atts2mode(sb, inode);
273         adfs_adfs2unix_time(&inode->i_mtime, inode);
274         inode->i_atime = inode->i_mtime;
275         inode->i_ctime = inode->i_mtime;
276 
277         if (S_ISDIR(inode->i_mode)) {
278                 inode->i_op     = &adfs_dir_inode_operations;
279                 inode->i_fop    = &adfs_dir_operations;
280         } else if (S_ISREG(inode->i_mode)) {
281                 inode->i_op     = &adfs_file_inode_operations;
282                 inode->i_fop    = &adfs_file_operations;
283                 inode->i_mapping->a_ops = &adfs_aops;
284                 ADFS_I(inode)->mmu_private = inode->i_size;
285         }
286 
287         insert_inode_hash(inode);
288 
289 out:
290         return inode;
291 }
292 
293 /*
294  * Validate and convert a changed access mode/time to their ADFS equivalents.
295  * adfs_write_inode will actually write the information back to the directory
296  * later.
297  */
298 int
299 adfs_notify_change(struct dentry *dentry, struct iattr *attr)
300 {
301         struct inode *inode = d_inode(dentry);
302         struct super_block *sb = inode->i_sb;
303         unsigned int ia_valid = attr->ia_valid;
304         int error;
305         
306         error = inode_change_ok(inode, attr);
307 
308         /*
309          * we can't change the UID or GID of any file -
310          * we have a global UID/GID in the superblock
311          */
312         if ((ia_valid & ATTR_UID && !uid_eq(attr->ia_uid, ADFS_SB(sb)->s_uid)) ||
313             (ia_valid & ATTR_GID && !gid_eq(attr->ia_gid, ADFS_SB(sb)->s_gid)))
314                 error = -EPERM;
315 
316         if (error)
317                 goto out;
318 
319         /* XXX: this is missing some actual on-disk truncation.. */
320         if (ia_valid & ATTR_SIZE)
321                 truncate_setsize(inode, attr->ia_size);
322 
323         if (ia_valid & ATTR_MTIME) {
324                 inode->i_mtime = attr->ia_mtime;
325                 adfs_unix2adfs_time(inode, attr->ia_mtime.tv_sec);
326         }
327         /*
328          * FIXME: should we make these == to i_mtime since we don't
329          * have the ability to represent them in our filesystem?
330          */
331         if (ia_valid & ATTR_ATIME)
332                 inode->i_atime = attr->ia_atime;
333         if (ia_valid & ATTR_CTIME)
334                 inode->i_ctime = attr->ia_ctime;
335         if (ia_valid & ATTR_MODE) {
336                 ADFS_I(inode)->attr = adfs_mode2atts(sb, inode);
337                 inode->i_mode = adfs_atts2mode(sb, inode);
338         }
339 
340         /*
341          * FIXME: should we be marking this inode dirty even if
342          * we don't have any metadata to write back?
343          */
344         if (ia_valid & (ATTR_SIZE | ATTR_MTIME | ATTR_MODE))
345                 mark_inode_dirty(inode);
346 out:
347         return error;
348 }
349 
350 /*
351  * write an existing inode back to the directory, and therefore the disk.
352  * The adfs-specific inode data has already been updated by
353  * adfs_notify_change()
354  */
355 int adfs_write_inode(struct inode *inode, struct writeback_control *wbc)
356 {
357         struct super_block *sb = inode->i_sb;
358         struct object_info obj;
359         int ret;
360 
361         obj.file_id     = inode->i_ino;
362         obj.name_len    = 0;
363         obj.parent_id   = ADFS_I(inode)->parent_id;
364         obj.loadaddr    = ADFS_I(inode)->loadaddr;
365         obj.execaddr    = ADFS_I(inode)->execaddr;
366         obj.attr        = ADFS_I(inode)->attr;
367         obj.size        = inode->i_size;
368 
369         ret = adfs_dir_update(sb, &obj, wbc->sync_mode == WB_SYNC_ALL);
370         return ret;
371 }
372 

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