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Linux/fs/bfs/dir.c

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  1 /*
  2  *      fs/bfs/dir.c
  3  *      BFS directory operations.
  4  *      Copyright (C) 1999,2000  Tigran Aivazian <tigran@veritas.com>
  5  *      Made endianness-clean by Andrew Stribblehill <ads@wompom.org> 2005
  6  */
  7 
  8 #include <linux/time.h>
  9 #include <linux/string.h>
 10 #include <linux/fs.h>
 11 #include <linux/buffer_head.h>
 12 #include <linux/sched.h>
 13 #include "bfs.h"
 14 
 15 #undef DEBUG
 16 
 17 #ifdef DEBUG
 18 #define dprintf(x...)   printf(x)
 19 #else
 20 #define dprintf(x...)
 21 #endif
 22 
 23 static int bfs_add_entry(struct inode *dir, const unsigned char *name,
 24                                                 int namelen, int ino);
 25 static struct buffer_head *bfs_find_entry(struct inode *dir,
 26                                 const unsigned char *name, int namelen,
 27                                 struct bfs_dirent **res_dir);
 28 
 29 static int bfs_readdir(struct file *f, struct dir_context *ctx)
 30 {
 31         struct inode *dir = file_inode(f);
 32         struct buffer_head *bh;
 33         struct bfs_dirent *de;
 34         unsigned int offset;
 35         int block;
 36 
 37         if (ctx->pos & (BFS_DIRENT_SIZE - 1)) {
 38                 printf("Bad f_pos=%08lx for %s:%08lx\n",
 39                                         (unsigned long)ctx->pos,
 40                                         dir->i_sb->s_id, dir->i_ino);
 41                 return -EINVAL;
 42         }
 43 
 44         while (ctx->pos < dir->i_size) {
 45                 offset = ctx->pos & (BFS_BSIZE - 1);
 46                 block = BFS_I(dir)->i_sblock + (ctx->pos >> BFS_BSIZE_BITS);
 47                 bh = sb_bread(dir->i_sb, block);
 48                 if (!bh) {
 49                         ctx->pos += BFS_BSIZE - offset;
 50                         continue;
 51                 }
 52                 do {
 53                         de = (struct bfs_dirent *)(bh->b_data + offset);
 54                         if (de->ino) {
 55                                 int size = strnlen(de->name, BFS_NAMELEN);
 56                                 if (!dir_emit(ctx, de->name, size,
 57                                                 le16_to_cpu(de->ino),
 58                                                 DT_UNKNOWN)) {
 59                                         brelse(bh);
 60                                         return 0;
 61                                 }
 62                         }
 63                         offset += BFS_DIRENT_SIZE;
 64                         ctx->pos += BFS_DIRENT_SIZE;
 65                 } while ((offset < BFS_BSIZE) && (ctx->pos < dir->i_size));
 66                 brelse(bh);
 67         }
 68         return 0;
 69 }
 70 
 71 const struct file_operations bfs_dir_operations = {
 72         .read           = generic_read_dir,
 73         .iterate        = bfs_readdir,
 74         .fsync          = generic_file_fsync,
 75         .llseek         = generic_file_llseek,
 76 };
 77 
 78 static int bfs_create(struct inode *dir, struct dentry *dentry, umode_t mode,
 79                                                 bool excl)
 80 {
 81         int err;
 82         struct inode *inode;
 83         struct super_block *s = dir->i_sb;
 84         struct bfs_sb_info *info = BFS_SB(s);
 85         unsigned long ino;
 86 
 87         inode = new_inode(s);
 88         if (!inode)
 89                 return -ENOMEM;
 90         mutex_lock(&info->bfs_lock);
 91         ino = find_first_zero_bit(info->si_imap, info->si_lasti + 1);
 92         if (ino > info->si_lasti) {
 93                 mutex_unlock(&info->bfs_lock);
 94                 iput(inode);
 95                 return -ENOSPC;
 96         }
 97         set_bit(ino, info->si_imap);
 98         info->si_freei--;
 99         inode_init_owner(inode, dir, mode);
100         inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME_SEC;
101         inode->i_blocks = 0;
102         inode->i_op = &bfs_file_inops;
103         inode->i_fop = &bfs_file_operations;
104         inode->i_mapping->a_ops = &bfs_aops;
105         inode->i_ino = ino;
106         BFS_I(inode)->i_dsk_ino = ino;
107         BFS_I(inode)->i_sblock = 0;
108         BFS_I(inode)->i_eblock = 0;
109         insert_inode_hash(inode);
110         mark_inode_dirty(inode);
111         bfs_dump_imap("create", s);
112 
113         err = bfs_add_entry(dir, dentry->d_name.name, dentry->d_name.len,
114                                                         inode->i_ino);
115         if (err) {
116                 inode_dec_link_count(inode);
117                 mutex_unlock(&info->bfs_lock);
118                 iput(inode);
119                 return err;
120         }
121         mutex_unlock(&info->bfs_lock);
122         d_instantiate(dentry, inode);
123         return 0;
124 }
125 
126 static struct dentry *bfs_lookup(struct inode *dir, struct dentry *dentry,
127                                                 unsigned int flags)
128 {
129         struct inode *inode = NULL;
130         struct buffer_head *bh;
131         struct bfs_dirent *de;
132         struct bfs_sb_info *info = BFS_SB(dir->i_sb);
133 
134         if (dentry->d_name.len > BFS_NAMELEN)
135                 return ERR_PTR(-ENAMETOOLONG);
136 
137         mutex_lock(&info->bfs_lock);
138         bh = bfs_find_entry(dir, dentry->d_name.name, dentry->d_name.len, &de);
139         if (bh) {
140                 unsigned long ino = (unsigned long)le16_to_cpu(de->ino);
141                 brelse(bh);
142                 inode = bfs_iget(dir->i_sb, ino);
143                 if (IS_ERR(inode)) {
144                         mutex_unlock(&info->bfs_lock);
145                         return ERR_CAST(inode);
146                 }
147         }
148         mutex_unlock(&info->bfs_lock);
149         d_add(dentry, inode);
150         return NULL;
151 }
152 
153 static int bfs_link(struct dentry *old, struct inode *dir,
154                                                 struct dentry *new)
155 {
156         struct inode *inode = d_inode(old);
157         struct bfs_sb_info *info = BFS_SB(inode->i_sb);
158         int err;
159 
160         mutex_lock(&info->bfs_lock);
161         err = bfs_add_entry(dir, new->d_name.name, new->d_name.len,
162                                                         inode->i_ino);
163         if (err) {
164                 mutex_unlock(&info->bfs_lock);
165                 return err;
166         }
167         inc_nlink(inode);
168         inode->i_ctime = CURRENT_TIME_SEC;
169         mark_inode_dirty(inode);
170         ihold(inode);
171         d_instantiate(new, inode);
172         mutex_unlock(&info->bfs_lock);
173         return 0;
174 }
175 
176 static int bfs_unlink(struct inode *dir, struct dentry *dentry)
177 {
178         int error = -ENOENT;
179         struct inode *inode = d_inode(dentry);
180         struct buffer_head *bh;
181         struct bfs_dirent *de;
182         struct bfs_sb_info *info = BFS_SB(inode->i_sb);
183 
184         mutex_lock(&info->bfs_lock);
185         bh = bfs_find_entry(dir, dentry->d_name.name, dentry->d_name.len, &de);
186         if (!bh || (le16_to_cpu(de->ino) != inode->i_ino))
187                 goto out_brelse;
188 
189         if (!inode->i_nlink) {
190                 printf("unlinking non-existent file %s:%lu (nlink=%d)\n",
191                                         inode->i_sb->s_id, inode->i_ino,
192                                         inode->i_nlink);
193                 set_nlink(inode, 1);
194         }
195         de->ino = 0;
196         mark_buffer_dirty_inode(bh, dir);
197         dir->i_ctime = dir->i_mtime = CURRENT_TIME_SEC;
198         mark_inode_dirty(dir);
199         inode->i_ctime = dir->i_ctime;
200         inode_dec_link_count(inode);
201         error = 0;
202 
203 out_brelse:
204         brelse(bh);
205         mutex_unlock(&info->bfs_lock);
206         return error;
207 }
208 
209 static int bfs_rename(struct inode *old_dir, struct dentry *old_dentry,
210                         struct inode *new_dir, struct dentry *new_dentry)
211 {
212         struct inode *old_inode, *new_inode;
213         struct buffer_head *old_bh, *new_bh;
214         struct bfs_dirent *old_de, *new_de;
215         struct bfs_sb_info *info;
216         int error = -ENOENT;
217 
218         old_bh = new_bh = NULL;
219         old_inode = d_inode(old_dentry);
220         if (S_ISDIR(old_inode->i_mode))
221                 return -EINVAL;
222 
223         info = BFS_SB(old_inode->i_sb);
224 
225         mutex_lock(&info->bfs_lock);
226         old_bh = bfs_find_entry(old_dir, 
227                                 old_dentry->d_name.name, 
228                                 old_dentry->d_name.len, &old_de);
229 
230         if (!old_bh || (le16_to_cpu(old_de->ino) != old_inode->i_ino))
231                 goto end_rename;
232 
233         error = -EPERM;
234         new_inode = d_inode(new_dentry);
235         new_bh = bfs_find_entry(new_dir, 
236                                 new_dentry->d_name.name, 
237                                 new_dentry->d_name.len, &new_de);
238 
239         if (new_bh && !new_inode) {
240                 brelse(new_bh);
241                 new_bh = NULL;
242         }
243         if (!new_bh) {
244                 error = bfs_add_entry(new_dir, 
245                                         new_dentry->d_name.name,
246                                         new_dentry->d_name.len,
247                                         old_inode->i_ino);
248                 if (error)
249                         goto end_rename;
250         }
251         old_de->ino = 0;
252         old_dir->i_ctime = old_dir->i_mtime = CURRENT_TIME_SEC;
253         mark_inode_dirty(old_dir);
254         if (new_inode) {
255                 new_inode->i_ctime = CURRENT_TIME_SEC;
256                 inode_dec_link_count(new_inode);
257         }
258         mark_buffer_dirty_inode(old_bh, old_dir);
259         error = 0;
260 
261 end_rename:
262         mutex_unlock(&info->bfs_lock);
263         brelse(old_bh);
264         brelse(new_bh);
265         return error;
266 }
267 
268 const struct inode_operations bfs_dir_inops = {
269         .create                 = bfs_create,
270         .lookup                 = bfs_lookup,
271         .link                   = bfs_link,
272         .unlink                 = bfs_unlink,
273         .rename                 = bfs_rename,
274 };
275 
276 static int bfs_add_entry(struct inode *dir, const unsigned char *name,
277                                                         int namelen, int ino)
278 {
279         struct buffer_head *bh;
280         struct bfs_dirent *de;
281         int block, sblock, eblock, off, pos;
282         int i;
283 
284         dprintf("name=%s, namelen=%d\n", name, namelen);
285 
286         if (!namelen)
287                 return -ENOENT;
288         if (namelen > BFS_NAMELEN)
289                 return -ENAMETOOLONG;
290 
291         sblock = BFS_I(dir)->i_sblock;
292         eblock = BFS_I(dir)->i_eblock;
293         for (block = sblock; block <= eblock; block++) {
294                 bh = sb_bread(dir->i_sb, block);
295                 if (!bh)
296                         return -EIO;
297                 for (off = 0; off < BFS_BSIZE; off += BFS_DIRENT_SIZE) {
298                         de = (struct bfs_dirent *)(bh->b_data + off);
299                         if (!de->ino) {
300                                 pos = (block - sblock) * BFS_BSIZE + off;
301                                 if (pos >= dir->i_size) {
302                                         dir->i_size += BFS_DIRENT_SIZE;
303                                         dir->i_ctime = CURRENT_TIME_SEC;
304                                 }
305                                 dir->i_mtime = CURRENT_TIME_SEC;
306                                 mark_inode_dirty(dir);
307                                 de->ino = cpu_to_le16((u16)ino);
308                                 for (i = 0; i < BFS_NAMELEN; i++)
309                                         de->name[i] =
310                                                 (i < namelen) ? name[i] : 0;
311                                 mark_buffer_dirty_inode(bh, dir);
312                                 brelse(bh);
313                                 return 0;
314                         }
315                 }
316                 brelse(bh);
317         }
318         return -ENOSPC;
319 }
320 
321 static inline int bfs_namecmp(int len, const unsigned char *name,
322                                                         const char *buffer)
323 {
324         if ((len < BFS_NAMELEN) && buffer[len])
325                 return 0;
326         return !memcmp(name, buffer, len);
327 }
328 
329 static struct buffer_head *bfs_find_entry(struct inode *dir,
330                         const unsigned char *name, int namelen,
331                         struct bfs_dirent **res_dir)
332 {
333         unsigned long block = 0, offset = 0;
334         struct buffer_head *bh = NULL;
335         struct bfs_dirent *de;
336 
337         *res_dir = NULL;
338         if (namelen > BFS_NAMELEN)
339                 return NULL;
340 
341         while (block * BFS_BSIZE + offset < dir->i_size) {
342                 if (!bh) {
343                         bh = sb_bread(dir->i_sb, BFS_I(dir)->i_sblock + block);
344                         if (!bh) {
345                                 block++;
346                                 continue;
347                         }
348                 }
349                 de = (struct bfs_dirent *)(bh->b_data + offset);
350                 offset += BFS_DIRENT_SIZE;
351                 if (le16_to_cpu(de->ino) &&
352                                 bfs_namecmp(namelen, name, de->name)) {
353                         *res_dir = de;
354                         return bh;
355                 }
356                 if (offset < bh->b_size)
357                         continue;
358                 brelse(bh);
359                 bh = NULL;
360                 offset = 0;
361                 block++;
362         }
363         brelse(bh);
364         return NULL;
365 }
366 

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