[PATCH] r/o bind mounts: unlink: monitor i_nlink
[linux-3.10.git] / fs / bfs / dir.c
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/smp_lock.h>
12 #include <linux/buffer_head.h>
13 #include <linux/sched.h>
14 #include "bfs.h"
15
16 #undef DEBUG
17
18 #ifdef DEBUG
19 #define dprintf(x...)   printf(x)
20 #else
21 #define dprintf(x...)
22 #endif
23
24 static int bfs_add_entry(struct inode * dir, const unsigned char * name, int namelen, int ino);
25 static struct buffer_head * bfs_find_entry(struct inode * dir, 
26         const unsigned char * name, int namelen, struct bfs_dirent ** res_dir);
27
28 static int bfs_readdir(struct file * f, void * dirent, filldir_t filldir)
29 {
30         struct inode * dir = f->f_dentry->d_inode;
31         struct buffer_head * bh;
32         struct bfs_dirent * de;
33         unsigned int offset;
34         int block;
35
36         lock_kernel();
37
38         if (f->f_pos & (BFS_DIRENT_SIZE-1)) {
39                 printf("Bad f_pos=%08lx for %s:%08lx\n", (unsigned long)f->f_pos, 
40                         dir->i_sb->s_id, dir->i_ino);
41                 unlock_kernel();
42                 return -EBADF;
43         }
44
45         while (f->f_pos < dir->i_size) {
46                 offset = f->f_pos & (BFS_BSIZE-1);
47                 block = BFS_I(dir)->i_sblock + (f->f_pos >> BFS_BSIZE_BITS);
48                 bh = sb_bread(dir->i_sb, block);
49                 if (!bh) {
50                         f->f_pos += BFS_BSIZE - offset;
51                         continue;
52                 }
53                 do {
54                         de = (struct bfs_dirent *)(bh->b_data + offset);
55                         if (de->ino) {
56                                 int size = strnlen(de->name, BFS_NAMELEN);
57                                 if (filldir(dirent, de->name, size, f->f_pos, le16_to_cpu(de->ino), DT_UNKNOWN) < 0) {
58                                         brelse(bh);
59                                         unlock_kernel();
60                                         return 0;
61                                 }
62                         }
63                         offset += BFS_DIRENT_SIZE;
64                         f->f_pos += BFS_DIRENT_SIZE;
65                 } while (offset < BFS_BSIZE && f->f_pos < dir->i_size);
66                 brelse(bh);
67         }
68
69         unlock_kernel();
70         return 0;       
71 }
72
73 const struct file_operations bfs_dir_operations = {
74         .read           = generic_read_dir,
75         .readdir        = bfs_readdir,
76         .fsync          = file_fsync,
77 };
78
79 extern void dump_imap(const char *, struct super_block *);
80
81 static int bfs_create(struct inode * dir, struct dentry * dentry, int mode,
82                 struct nameidata *nd)
83 {
84         int err;
85         struct inode * inode;
86         struct super_block * s = dir->i_sb;
87         struct bfs_sb_info * info = BFS_SB(s);
88         unsigned long ino;
89
90         inode = new_inode(s);
91         if (!inode)
92                 return -ENOSPC;
93         lock_kernel();
94         ino = find_first_zero_bit(info->si_imap, info->si_lasti);
95         if (ino > info->si_lasti) {
96                 unlock_kernel();
97                 iput(inode);
98                 return -ENOSPC;
99         }
100         set_bit(ino, info->si_imap);    
101         info->si_freei--;
102         inode->i_uid = current->fsuid;
103         inode->i_gid = (dir->i_mode & S_ISGID) ? dir->i_gid : current->fsgid;
104         inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME_SEC;
105         inode->i_blocks = 0;
106         inode->i_op = &bfs_file_inops;
107         inode->i_fop = &bfs_file_operations;
108         inode->i_mapping->a_ops = &bfs_aops;
109         inode->i_mode = mode;
110         inode->i_ino = ino;
111         BFS_I(inode)->i_dsk_ino = ino;
112         BFS_I(inode)->i_sblock = 0;
113         BFS_I(inode)->i_eblock = 0;
114         insert_inode_hash(inode);
115         mark_inode_dirty(inode);
116         dump_imap("create",s);
117
118         err = bfs_add_entry(dir, dentry->d_name.name, dentry->d_name.len, inode->i_ino);
119         if (err) {
120                 inode_dec_link_count(inode);
121                 iput(inode);
122                 unlock_kernel();
123                 return err;
124         }
125         unlock_kernel();
126         d_instantiate(dentry, inode);
127         return 0;
128 }
129
130 static struct dentry * bfs_lookup(struct inode * dir, struct dentry * dentry, struct nameidata *nd)
131 {
132         struct inode * inode = NULL;
133         struct buffer_head * bh;
134         struct bfs_dirent * de;
135
136         if (dentry->d_name.len > BFS_NAMELEN)
137                 return ERR_PTR(-ENAMETOOLONG);
138
139         lock_kernel();
140         bh = bfs_find_entry(dir, dentry->d_name.name, dentry->d_name.len, &de);
141         if (bh) {
142                 unsigned long ino = (unsigned long)le16_to_cpu(de->ino);
143                 brelse(bh);
144                 inode = iget(dir->i_sb, ino);
145                 if (!inode) {
146                         unlock_kernel();
147                         return ERR_PTR(-EACCES);
148                 }
149         }
150         unlock_kernel();
151         d_add(dentry, inode);
152         return NULL;
153 }
154
155 static int bfs_link(struct dentry * old, struct inode * dir, struct dentry * new)
156 {
157         struct inode * inode = old->d_inode;
158         int err;
159
160         lock_kernel();
161         err = bfs_add_entry(dir, new->d_name.name, new->d_name.len, inode->i_ino);
162         if (err) {
163                 unlock_kernel();
164                 return err;
165         }
166         inode->i_nlink++;
167         inode->i_ctime = CURRENT_TIME_SEC;
168         mark_inode_dirty(inode);
169         atomic_inc(&inode->i_count);
170         d_instantiate(new, inode);
171         unlock_kernel();
172         return 0;
173 }
174
175
176 static int bfs_unlink(struct inode * dir, struct dentry * dentry)
177 {
178         int error = -ENOENT;
179         struct inode * inode;
180         struct buffer_head * bh;
181         struct bfs_dirent * de;
182
183         inode = dentry->d_inode;
184         lock_kernel();
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", inode->i_sb->s_id, 
191                                 inode->i_ino, inode->i_nlink);
192                 inode->i_nlink = 1;
193         }
194         de->ino = 0;
195         mark_buffer_dirty(bh);
196         dir->i_ctime = dir->i_mtime = CURRENT_TIME_SEC;
197         mark_inode_dirty(dir);
198         inode->i_ctime = dir->i_ctime;
199         inode_dec_link_count(inode);
200         error = 0;
201
202 out_brelse:
203         brelse(bh);
204         unlock_kernel();
205         return error;
206 }
207
208 static int bfs_rename(struct inode * old_dir, struct dentry * old_dentry, 
209                         struct inode * new_dir, struct dentry * new_dentry)
210 {
211         struct inode * old_inode, * new_inode;
212         struct buffer_head * old_bh, * new_bh;
213         struct bfs_dirent * old_de, * new_de;           
214         int error = -ENOENT;
215
216         old_bh = new_bh = NULL;
217         old_inode = old_dentry->d_inode;
218         if (S_ISDIR(old_inode->i_mode))
219                 return -EINVAL;
220
221         lock_kernel();
222         old_bh = bfs_find_entry(old_dir, 
223                                 old_dentry->d_name.name, 
224                                 old_dentry->d_name.len, &old_de);
225
226         if (!old_bh || le16_to_cpu(old_de->ino) != old_inode->i_ino)
227                 goto end_rename;
228
229         error = -EPERM;
230         new_inode = new_dentry->d_inode;
231         new_bh = bfs_find_entry(new_dir, 
232                                 new_dentry->d_name.name, 
233                                 new_dentry->d_name.len, &new_de);
234
235         if (new_bh && !new_inode) {
236                 brelse(new_bh);
237                 new_bh = NULL;
238         }
239         if (!new_bh) {
240                 error = bfs_add_entry(new_dir, 
241                                         new_dentry->d_name.name,
242                                         new_dentry->d_name.len, old_inode->i_ino);
243                 if (error)
244                         goto end_rename;
245         }
246         old_de->ino = 0;
247         old_dir->i_ctime = old_dir->i_mtime = CURRENT_TIME_SEC;
248         mark_inode_dirty(old_dir);
249         if (new_inode) {
250                 new_inode->i_ctime = CURRENT_TIME_SEC;
251                 inode_dec_link_count(new_inode);
252         }
253         mark_buffer_dirty(old_bh);
254         error = 0;
255
256 end_rename:
257         unlock_kernel();
258         brelse(old_bh);
259         brelse(new_bh);
260         return error;
261 }
262
263 struct inode_operations bfs_dir_inops = {
264         .create                 = bfs_create,
265         .lookup                 = bfs_lookup,
266         .link                   = bfs_link,
267         .unlink                 = bfs_unlink,
268         .rename                 = bfs_rename,
269 };
270
271 static int bfs_add_entry(struct inode * dir, const unsigned char * name, int namelen, int ino)
272 {
273         struct buffer_head * bh;
274         struct bfs_dirent * de;
275         int block, sblock, eblock, off, eoff;
276         int i;
277
278         dprintf("name=%s, namelen=%d\n", name, namelen);
279
280         if (!namelen)
281                 return -ENOENT;
282         if (namelen > BFS_NAMELEN)
283                 return -ENAMETOOLONG;
284
285         sblock = BFS_I(dir)->i_sblock;
286         eblock = BFS_I(dir)->i_eblock;
287         eoff = dir->i_size % BFS_BSIZE;
288         for (block=sblock; block<=eblock; block++) {
289                 bh = sb_bread(dir->i_sb, block);
290                 if(!bh) 
291                         return -ENOSPC;
292                 for (off=0; off<BFS_BSIZE; off+=BFS_DIRENT_SIZE) {
293                         de = (struct bfs_dirent *)(bh->b_data + off);
294                         if (block==eblock && off>=eoff) {
295                                 /* Do not read/interpret the garbage in the end of eblock. */
296                                 de->ino = 0;
297                         }
298                         if (!de->ino) {
299                                 if ((block-sblock)*BFS_BSIZE + off >= dir->i_size) {
300                                         dir->i_size += BFS_DIRENT_SIZE;
301                                         dir->i_ctime = CURRENT_TIME_SEC;
302                                 }
303                                 dir->i_mtime = CURRENT_TIME_SEC;
304                                 mark_inode_dirty(dir);
305                                 de->ino = cpu_to_le16((u16)ino);
306                                 for (i=0; i<BFS_NAMELEN; i++)
307                                         de->name[i] = (i < namelen) ? name[i] : 0;
308                                 mark_buffer_dirty(bh);
309                                 brelse(bh);
310                                 return 0;
311                         }
312                 }
313                 brelse(bh);
314         }
315         return -ENOSPC;
316 }
317
318 static inline int bfs_namecmp(int len, const unsigned char * name, const char * buffer)
319 {
320         if (len < BFS_NAMELEN && buffer[len])
321                 return 0;
322         return !memcmp(name, buffer, len);
323 }
324
325 static struct buffer_head * bfs_find_entry(struct inode * dir, 
326         const unsigned char * name, int namelen, struct bfs_dirent ** res_dir)
327 {
328         unsigned long block, offset;
329         struct buffer_head * bh;
330         struct bfs_dirent * de;
331
332         *res_dir = NULL;
333         if (namelen > BFS_NAMELEN)
334                 return NULL;
335         bh = NULL;
336         block = offset = 0;
337         while (block * BFS_BSIZE + offset < dir->i_size) {
338                 if (!bh) {
339                         bh = sb_bread(dir->i_sb, BFS_I(dir)->i_sblock + block);
340                         if (!bh) {
341                                 block++;
342                                 continue;
343                         }
344                 }
345                 de = (struct bfs_dirent *)(bh->b_data + offset);
346                 offset += BFS_DIRENT_SIZE;
347                 if (le16_to_cpu(de->ino) && bfs_namecmp(namelen, name, de->name)) {
348                         *res_dir = de;
349                         return bh;
350                 }
351                 if (offset < bh->b_size)
352                         continue;
353                 brelse(bh);
354                 bh = NULL;
355                 offset = 0;
356                 block++;
357         }
358         brelse(bh);
359         return NULL;
360 }