fs: dcache reduce branches in lookup path
[linux-2.6.git] / fs / reiserfs / dir.c
1 /*
2  * Copyright 2000 by Hans Reiser, licensing governed by reiserfs/README
3  */
4
5 #include <linux/string.h>
6 #include <linux/errno.h>
7 #include <linux/fs.h>
8 #include <linux/reiserfs_fs.h>
9 #include <linux/stat.h>
10 #include <linux/buffer_head.h>
11 #include <linux/slab.h>
12 #include <asm/uaccess.h>
13
14 extern const struct reiserfs_key MIN_KEY;
15
16 static int reiserfs_readdir(struct file *, void *, filldir_t);
17 static int reiserfs_dir_fsync(struct file *filp, int datasync);
18
19 const struct file_operations reiserfs_dir_operations = {
20         .llseek = generic_file_llseek,
21         .read = generic_read_dir,
22         .readdir = reiserfs_readdir,
23         .fsync = reiserfs_dir_fsync,
24         .unlocked_ioctl = reiserfs_ioctl,
25 #ifdef CONFIG_COMPAT
26         .compat_ioctl = reiserfs_compat_ioctl,
27 #endif
28 };
29
30 static int reiserfs_dir_fsync(struct file *filp, int datasync)
31 {
32         struct inode *inode = filp->f_mapping->host;
33         int err;
34         reiserfs_write_lock(inode->i_sb);
35         err = reiserfs_commit_for_inode(inode);
36         reiserfs_write_unlock(inode->i_sb);
37         if (err < 0)
38                 return err;
39         return 0;
40 }
41
42 #define store_ih(where,what) copy_item_head (where, what)
43
44 static inline bool is_privroot_deh(struct dentry *dir,
45                                    struct reiserfs_de_head *deh)
46 {
47         struct dentry *privroot = REISERFS_SB(dir->d_sb)->priv_root;
48         return (dir == dir->d_parent && privroot->d_inode &&
49                 deh->deh_objectid == INODE_PKEY(privroot->d_inode)->k_objectid);
50 }
51
52 int reiserfs_readdir_dentry(struct dentry *dentry, void *dirent,
53                            filldir_t filldir, loff_t *pos)
54 {
55         struct inode *inode = dentry->d_inode;
56         struct cpu_key pos_key; /* key of current position in the directory (key of directory entry) */
57         INITIALIZE_PATH(path_to_entry);
58         struct buffer_head *bh;
59         int item_num, entry_num;
60         const struct reiserfs_key *rkey;
61         struct item_head *ih, tmp_ih;
62         int search_res;
63         char *local_buf;
64         loff_t next_pos;
65         char small_buf[32];     /* avoid kmalloc if we can */
66         struct reiserfs_dir_entry de;
67         int ret = 0;
68
69         reiserfs_write_lock(inode->i_sb);
70
71         reiserfs_check_lock_depth(inode->i_sb, "readdir");
72
73         /* form key for search the next directory entry using f_pos field of
74            file structure */
75         make_cpu_key(&pos_key, inode, *pos ?: DOT_OFFSET, TYPE_DIRENTRY, 3);
76         next_pos = cpu_key_k_offset(&pos_key);
77
78         path_to_entry.reada = PATH_READA;
79         while (1) {
80               research:
81                 /* search the directory item, containing entry with specified key */
82                 search_res =
83                     search_by_entry_key(inode->i_sb, &pos_key, &path_to_entry,
84                                         &de);
85                 if (search_res == IO_ERROR) {
86                         // FIXME: we could just skip part of directory which could
87                         // not be read
88                         ret = -EIO;
89                         goto out;
90                 }
91                 entry_num = de.de_entry_num;
92                 bh = de.de_bh;
93                 item_num = de.de_item_num;
94                 ih = de.de_ih;
95                 store_ih(&tmp_ih, ih);
96
97                 /* we must have found item, that is item of this directory, */
98                 RFALSE(COMP_SHORT_KEYS(&(ih->ih_key), &pos_key),
99                        "vs-9000: found item %h does not match to dir we readdir %K",
100                        ih, &pos_key);
101                 RFALSE(item_num > B_NR_ITEMS(bh) - 1,
102                        "vs-9005 item_num == %d, item amount == %d",
103                        item_num, B_NR_ITEMS(bh));
104
105                 /* and entry must be not more than number of entries in the item */
106                 RFALSE(I_ENTRY_COUNT(ih) < entry_num,
107                        "vs-9010: entry number is too big %d (%d)",
108                        entry_num, I_ENTRY_COUNT(ih));
109
110                 if (search_res == POSITION_FOUND
111                     || entry_num < I_ENTRY_COUNT(ih)) {
112                         /* go through all entries in the directory item beginning from the entry, that has been found */
113                         struct reiserfs_de_head *deh =
114                             B_I_DEH(bh, ih) + entry_num;
115
116                         for (; entry_num < I_ENTRY_COUNT(ih);
117                              entry_num++, deh++) {
118                                 int d_reclen;
119                                 char *d_name;
120                                 off_t d_off;
121                                 ino_t d_ino;
122
123                                 if (!de_visible(deh))
124                                         /* it is hidden entry */
125                                         continue;
126                                 d_reclen = entry_length(bh, ih, entry_num);
127                                 d_name = B_I_DEH_ENTRY_FILE_NAME(bh, ih, deh);
128
129                                 if (d_reclen <= 0 ||
130                                     d_name + d_reclen > bh->b_data + bh->b_size) {
131                                         /* There is corrupted data in entry,
132                                          * We'd better stop here */
133                                         pathrelse(&path_to_entry);
134                                         ret = -EIO;
135                                         goto out;
136                                 }
137
138                                 if (!d_name[d_reclen - 1])
139                                         d_reclen = strlen(d_name);
140
141                                 if (d_reclen >
142                                     REISERFS_MAX_NAME(inode->i_sb->
143                                                       s_blocksize)) {
144                                         /* too big to send back to VFS */
145                                         continue;
146                                 }
147
148                                 /* Ignore the .reiserfs_priv entry */
149                                 if (is_privroot_deh(dentry, deh))
150                                         continue;
151
152                                 d_off = deh_offset(deh);
153                                 *pos = d_off;
154                                 d_ino = deh_objectid(deh);
155                                 if (d_reclen <= 32) {
156                                         local_buf = small_buf;
157                                 } else {
158                                         local_buf = kmalloc(d_reclen,
159                                                             GFP_NOFS);
160                                         if (!local_buf) {
161                                                 pathrelse(&path_to_entry);
162                                                 ret = -ENOMEM;
163                                                 goto out;
164                                         }
165                                         if (item_moved(&tmp_ih, &path_to_entry)) {
166                                                 kfree(local_buf);
167                                                 goto research;
168                                         }
169                                 }
170                                 // Note, that we copy name to user space via temporary
171                                 // buffer (local_buf) because filldir will block if
172                                 // user space buffer is swapped out. At that time
173                                 // entry can move to somewhere else
174                                 memcpy(local_buf, d_name, d_reclen);
175
176                                 /*
177                                  * Since filldir might sleep, we can release
178                                  * the write lock here for other waiters
179                                  */
180                                 reiserfs_write_unlock(inode->i_sb);
181                                 if (filldir
182                                     (dirent, local_buf, d_reclen, d_off, d_ino,
183                                      DT_UNKNOWN) < 0) {
184                                         reiserfs_write_lock(inode->i_sb);
185                                         if (local_buf != small_buf) {
186                                                 kfree(local_buf);
187                                         }
188                                         goto end;
189                                 }
190                                 reiserfs_write_lock(inode->i_sb);
191                                 if (local_buf != small_buf) {
192                                         kfree(local_buf);
193                                 }
194                                 // next entry should be looked for with such offset
195                                 next_pos = deh_offset(deh) + 1;
196
197                                 if (item_moved(&tmp_ih, &path_to_entry)) {
198                                         goto research;
199                                 }
200                         }       /* for */
201                 }
202
203                 if (item_num != B_NR_ITEMS(bh) - 1)
204                         // end of directory has been reached
205                         goto end;
206
207                 /* item we went through is last item of node. Using right
208                    delimiting key check is it directory end */
209                 rkey = get_rkey(&path_to_entry, inode->i_sb);
210                 if (!comp_le_keys(rkey, &MIN_KEY)) {
211                         /* set pos_key to key, that is the smallest and greater
212                            that key of the last entry in the item */
213                         set_cpu_key_k_offset(&pos_key, next_pos);
214                         continue;
215                 }
216
217                 if (COMP_SHORT_KEYS(rkey, &pos_key)) {
218                         // end of directory has been reached
219                         goto end;
220                 }
221
222                 /* directory continues in the right neighboring block */
223                 set_cpu_key_k_offset(&pos_key,
224                                      le_key_k_offset(KEY_FORMAT_3_5, rkey));
225
226         }                       /* while */
227
228 end:
229         *pos = next_pos;
230         pathrelse(&path_to_entry);
231         reiserfs_check_path(&path_to_entry);
232 out:
233         reiserfs_write_unlock(inode->i_sb);
234         return ret;
235 }
236
237 static int reiserfs_readdir(struct file *file, void *dirent, filldir_t filldir)
238 {
239         struct dentry *dentry = file->f_path.dentry;
240         return reiserfs_readdir_dentry(dentry, dirent, filldir, &file->f_pos);
241 }
242
243 /* compose directory item containing "." and ".." entries (entries are
244    not aligned to 4 byte boundary) */
245 /* the last four params are LE */
246 void make_empty_dir_item_v1(char *body, __le32 dirid, __le32 objid,
247                             __le32 par_dirid, __le32 par_objid)
248 {
249         struct reiserfs_de_head *deh;
250
251         memset(body, 0, EMPTY_DIR_SIZE_V1);
252         deh = (struct reiserfs_de_head *)body;
253
254         /* direntry header of "." */
255         put_deh_offset(&(deh[0]), DOT_OFFSET);
256         /* these two are from make_le_item_head, and are are LE */
257         deh[0].deh_dir_id = dirid;
258         deh[0].deh_objectid = objid;
259         deh[0].deh_state = 0;   /* Endian safe if 0 */
260         put_deh_location(&(deh[0]), EMPTY_DIR_SIZE_V1 - strlen("."));
261         mark_de_visible(&(deh[0]));
262
263         /* direntry header of ".." */
264         put_deh_offset(&(deh[1]), DOT_DOT_OFFSET);
265         /* key of ".." for the root directory */
266         /* these two are from the inode, and are are LE */
267         deh[1].deh_dir_id = par_dirid;
268         deh[1].deh_objectid = par_objid;
269         deh[1].deh_state = 0;   /* Endian safe if 0 */
270         put_deh_location(&(deh[1]), deh_location(&(deh[0])) - strlen(".."));
271         mark_de_visible(&(deh[1]));
272
273         /* copy ".." and "." */
274         memcpy(body + deh_location(&(deh[0])), ".", 1);
275         memcpy(body + deh_location(&(deh[1])), "..", 2);
276 }
277
278 /* compose directory item containing "." and ".." entries */
279 void make_empty_dir_item(char *body, __le32 dirid, __le32 objid,
280                          __le32 par_dirid, __le32 par_objid)
281 {
282         struct reiserfs_de_head *deh;
283
284         memset(body, 0, EMPTY_DIR_SIZE);
285         deh = (struct reiserfs_de_head *)body;
286
287         /* direntry header of "." */
288         put_deh_offset(&(deh[0]), DOT_OFFSET);
289         /* these two are from make_le_item_head, and are are LE */
290         deh[0].deh_dir_id = dirid;
291         deh[0].deh_objectid = objid;
292         deh[0].deh_state = 0;   /* Endian safe if 0 */
293         put_deh_location(&(deh[0]), EMPTY_DIR_SIZE - ROUND_UP(strlen(".")));
294         mark_de_visible(&(deh[0]));
295
296         /* direntry header of ".." */
297         put_deh_offset(&(deh[1]), DOT_DOT_OFFSET);
298         /* key of ".." for the root directory */
299         /* these two are from the inode, and are are LE */
300         deh[1].deh_dir_id = par_dirid;
301         deh[1].deh_objectid = par_objid;
302         deh[1].deh_state = 0;   /* Endian safe if 0 */
303         put_deh_location(&(deh[1]),
304                          deh_location(&(deh[0])) - ROUND_UP(strlen("..")));
305         mark_de_visible(&(deh[1]));
306
307         /* copy ".." and "." */
308         memcpy(body + deh_location(&(deh[0])), ".", 1);
309         memcpy(body + deh_location(&(deh[1])), "..", 2);
310 }