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Linux/fs/qnx6/dir.c

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  1 /*
  2  * QNX6 file system, Linux implementation.
  3  *
  4  * Version : 1.0.0
  5  *
  6  * History :
  7  *
  8  * 01-02-2012 by Kai Bankett (chaosman@ontika.net) : first release.
  9  * 16-02-2012 pagemap extension by Al Viro
 10  *
 11  */
 12 
 13 #include "qnx6.h"
 14 
 15 static unsigned qnx6_lfile_checksum(char *name, unsigned size)
 16 {
 17         unsigned crc = 0;
 18         char *end = name + size;
 19         while (name < end) {
 20                 crc = ((crc >> 1) + *(name++)) ^
 21                         ((crc & 0x00000001) ? 0x80000000 : 0);
 22         }
 23         return crc;
 24 }
 25 
 26 static struct page *qnx6_get_page(struct inode *dir, unsigned long n)
 27 {
 28         struct address_space *mapping = dir->i_mapping;
 29         struct page *page = read_mapping_page(mapping, n, NULL);
 30         if (!IS_ERR(page))
 31                 kmap(page);
 32         return page;
 33 }
 34 
 35 static inline unsigned long dir_pages(struct inode *inode)
 36 {
 37         return (inode->i_size+PAGE_CACHE_SIZE-1)>>PAGE_CACHE_SHIFT;
 38 }
 39 
 40 static unsigned last_entry(struct inode *inode, unsigned long page_nr)
 41 {
 42         unsigned long last_byte = inode->i_size;
 43         last_byte -= page_nr << PAGE_CACHE_SHIFT;
 44         if (last_byte > PAGE_CACHE_SIZE)
 45                 last_byte = PAGE_CACHE_SIZE;
 46         return last_byte / QNX6_DIR_ENTRY_SIZE;
 47 }
 48 
 49 static struct qnx6_long_filename *qnx6_longname(struct super_block *sb,
 50                                          struct qnx6_long_dir_entry *de,
 51                                          struct page **p)
 52 {
 53         struct qnx6_sb_info *sbi = QNX6_SB(sb);
 54         u32 s = fs32_to_cpu(sbi, de->de_long_inode); /* in block units */
 55         u32 n = s >> (PAGE_CACHE_SHIFT - sb->s_blocksize_bits); /* in pages */
 56         /* within page */
 57         u32 offs = (s << sb->s_blocksize_bits) & ~PAGE_CACHE_MASK;
 58         struct address_space *mapping = sbi->longfile->i_mapping;
 59         struct page *page = read_mapping_page(mapping, n, NULL);
 60         if (IS_ERR(page))
 61                 return ERR_CAST(page);
 62         kmap(*p = page);
 63         return (struct qnx6_long_filename *)(page_address(page) + offs);
 64 }
 65 
 66 static int qnx6_dir_longfilename(struct inode *inode,
 67                         struct qnx6_long_dir_entry *de,
 68                         struct dir_context *ctx,
 69                         unsigned de_inode)
 70 {
 71         struct qnx6_long_filename *lf;
 72         struct super_block *s = inode->i_sb;
 73         struct qnx6_sb_info *sbi = QNX6_SB(s);
 74         struct page *page;
 75         int lf_size;
 76 
 77         if (de->de_size != 0xff) {
 78                 /* error - long filename entries always have size 0xff
 79                    in direntry */
 80                 printk(KERN_ERR "qnx6: invalid direntry size (%i).\n",
 81                                 de->de_size);
 82                 return 0;
 83         }
 84         lf = qnx6_longname(s, de, &page);
 85         if (IS_ERR(lf)) {
 86                 printk(KERN_ERR "qnx6:Error reading longname\n");
 87                 return 0;
 88         }
 89 
 90         lf_size = fs16_to_cpu(sbi, lf->lf_size);
 91 
 92         if (lf_size > QNX6_LONG_NAME_MAX) {
 93                 QNX6DEBUG((KERN_INFO "file %s\n", lf->lf_fname));
 94                 printk(KERN_ERR "qnx6:Filename too long (%i)\n", lf_size);
 95                 qnx6_put_page(page);
 96                 return 0;
 97         }
 98 
 99         /* calc & validate longfilename checksum
100            mmi 3g filesystem does not have that checksum */
101         if (!test_opt(s, MMI_FS) && fs32_to_cpu(sbi, de->de_checksum) !=
102                         qnx6_lfile_checksum(lf->lf_fname, lf_size))
103                 printk(KERN_INFO "qnx6: long filename checksum error.\n");
104 
105         QNX6DEBUG((KERN_INFO "qnx6_readdir:%.*s inode:%u\n",
106                                         lf_size, lf->lf_fname, de_inode));
107         if (!dir_emit(ctx, lf->lf_fname, lf_size, de_inode, DT_UNKNOWN)) {
108                 qnx6_put_page(page);
109                 return 0;
110         }
111 
112         qnx6_put_page(page);
113         /* success */
114         return 1;
115 }
116 
117 static int qnx6_readdir(struct file *file, struct dir_context *ctx)
118 {
119         struct inode *inode = file_inode(file);
120         struct super_block *s = inode->i_sb;
121         struct qnx6_sb_info *sbi = QNX6_SB(s);
122         loff_t pos = ctx->pos & ~(QNX6_DIR_ENTRY_SIZE - 1);
123         unsigned long npages = dir_pages(inode);
124         unsigned long n = pos >> PAGE_CACHE_SHIFT;
125         unsigned start = (pos & ~PAGE_CACHE_MASK) / QNX6_DIR_ENTRY_SIZE;
126         bool done = false;
127 
128         ctx->pos = pos;
129         if (ctx->pos >= inode->i_size)
130                 return 0;
131 
132         for ( ; !done && n < npages; n++, start = 0) {
133                 struct page *page = qnx6_get_page(inode, n);
134                 int limit = last_entry(inode, n);
135                 struct qnx6_dir_entry *de;
136                 int i = start;
137 
138                 if (IS_ERR(page)) {
139                         printk(KERN_ERR "qnx6_readdir: read failed\n");
140                         ctx->pos = (n + 1) << PAGE_CACHE_SHIFT;
141                         return PTR_ERR(page);
142                 }
143                 de = ((struct qnx6_dir_entry *)page_address(page)) + start;
144                 for (; i < limit; i++, de++, ctx->pos += QNX6_DIR_ENTRY_SIZE) {
145                         int size = de->de_size;
146                         u32 no_inode = fs32_to_cpu(sbi, de->de_inode);
147 
148                         if (!no_inode || !size)
149                                 continue;
150 
151                         if (size > QNX6_SHORT_NAME_MAX) {
152                                 /* long filename detected
153                                    get the filename from long filename
154                                    structure / block */
155                                 if (!qnx6_dir_longfilename(inode,
156                                         (struct qnx6_long_dir_entry *)de,
157                                         ctx, no_inode)) {
158                                         done = true;
159                                         break;
160                                 }
161                         } else {
162                                 QNX6DEBUG((KERN_INFO "qnx6_readdir:%.*s"
163                                    " inode:%u\n", size, de->de_fname,
164                                                         no_inode));
165                                 if (!dir_emit(ctx, de->de_fname, size,
166                                       no_inode, DT_UNKNOWN)) {
167                                         done = true;
168                                         break;
169                                 }
170                         }
171                 }
172                 qnx6_put_page(page);
173         }
174         return 0;
175 }
176 
177 /*
178  * check if the long filename is correct.
179  */
180 static unsigned qnx6_long_match(int len, const char *name,
181                         struct qnx6_long_dir_entry *de, struct inode *dir)
182 {
183         struct super_block *s = dir->i_sb;
184         struct qnx6_sb_info *sbi = QNX6_SB(s);
185         struct page *page;
186         int thislen;
187         struct qnx6_long_filename *lf = qnx6_longname(s, de, &page);
188 
189         if (IS_ERR(lf))
190                 return 0;
191 
192         thislen = fs16_to_cpu(sbi, lf->lf_size);
193         if (len != thislen) {
194                 qnx6_put_page(page);
195                 return 0;
196         }
197         if (memcmp(name, lf->lf_fname, len) == 0) {
198                 qnx6_put_page(page);
199                 return fs32_to_cpu(sbi, de->de_inode);
200         }
201         qnx6_put_page(page);
202         return 0;
203 }
204 
205 /*
206  * check if the filename is correct.
207  */
208 static unsigned qnx6_match(struct super_block *s, int len, const char *name,
209                         struct qnx6_dir_entry *de)
210 {
211         struct qnx6_sb_info *sbi = QNX6_SB(s);
212         if (memcmp(name, de->de_fname, len) == 0)
213                 return fs32_to_cpu(sbi, de->de_inode);
214         return 0;
215 }
216 
217 
218 unsigned qnx6_find_entry(int len, struct inode *dir, const char *name,
219                          struct page **res_page)
220 {
221         struct super_block *s = dir->i_sb;
222         struct qnx6_inode_info *ei = QNX6_I(dir);
223         struct page *page = NULL;
224         unsigned long start, n;
225         unsigned long npages = dir_pages(dir);
226         unsigned ino;
227         struct qnx6_dir_entry *de;
228         struct qnx6_long_dir_entry *lde;
229 
230         *res_page = NULL;
231 
232         if (npages == 0)
233                 return 0;
234         start = ei->i_dir_start_lookup;
235         if (start >= npages)
236                 start = 0;
237         n = start;
238 
239         do {
240                 page = qnx6_get_page(dir, n);
241                 if (!IS_ERR(page)) {
242                         int limit = last_entry(dir, n);
243                         int i;
244 
245                         de = (struct qnx6_dir_entry *)page_address(page);
246                         for (i = 0; i < limit; i++, de++) {
247                                 if (len <= QNX6_SHORT_NAME_MAX) {
248                                         /* short filename */
249                                         if (len != de->de_size)
250                                                 continue;
251                                         ino = qnx6_match(s, len, name, de);
252                                         if (ino)
253                                                 goto found;
254                                 } else if (de->de_size == 0xff) {
255                                         /* deal with long filename */
256                                         lde = (struct qnx6_long_dir_entry *)de;
257                                         ino = qnx6_long_match(len,
258                                                                 name, lde, dir);
259                                         if (ino)
260                                                 goto found;
261                                 } else
262                                         printk(KERN_ERR "qnx6: undefined "
263                                                 "filename size in inode.\n");
264                         }
265                         qnx6_put_page(page);
266                 }
267 
268                 if (++n >= npages)
269                         n = 0;
270         } while (n != start);
271         return 0;
272 
273 found:
274         *res_page = page;
275         ei->i_dir_start_lookup = n;
276         return ino;
277 }
278 
279 const struct file_operations qnx6_dir_operations = {
280         .llseek         = generic_file_llseek,
281         .read           = generic_read_dir,
282         .iterate        = qnx6_readdir,
283         .fsync          = generic_file_fsync,
284 };
285 
286 const struct inode_operations qnx6_dir_inode_operations = {
287         .lookup         = qnx6_lookup,
288 };
289 

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