1 // SPDX-License-Identifier: GPL-2.0-only
3 * OMFS (as used by RIO Karma) directory operations.
4 * Copyright (C) 2005 Bob Copeland <me@bobcopeland.com>
8 #include <linux/ctype.h>
9 #include <linux/buffer_head.h>
12 static int omfs_hash(const char *name, int namelen, int mod)
15 for (i = 0; i < namelen; i++)
16 hash ^= tolower(name[i]) << (i % 24);
21 * Finds the bucket for a given name and reads the containing block;
22 * *ofs is set to the offset of the first list entry.
24 static struct buffer_head *omfs_get_bucket(struct inode *dir,
25 const char *name, int namelen, int *ofs)
27 int nbuckets = (dir->i_size - OMFS_DIR_START)/8;
28 int bucket = omfs_hash(name, namelen, nbuckets);
30 *ofs = OMFS_DIR_START + bucket * 8;
31 return omfs_bread(dir->i_sb, dir->i_ino);
34 static struct buffer_head *omfs_scan_list(struct inode *dir, u64 block,
35 const char *name, int namelen,
38 struct buffer_head *bh;
39 struct omfs_inode *oi;
44 bh = omfs_bread(dir->i_sb, block);
50 oi = (struct omfs_inode *) bh->b_data;
51 if (omfs_is_bad(OMFS_SB(dir->i_sb), &oi->i_head, block)) {
56 if (strncmp(oi->i_name, name, namelen) == 0)
60 block = be64_to_cpu(oi->i_sibling);
67 static struct buffer_head *omfs_find_entry(struct inode *dir,
68 const char *name, int namelen)
70 struct buffer_head *bh;
74 bh = omfs_get_bucket(dir, name, namelen, &ofs);
78 block = be64_to_cpu(*((__be64 *) &bh->b_data[ofs]));
81 return omfs_scan_list(dir, block, name, namelen, &dummy);
84 int omfs_make_empty(struct inode *inode, struct super_block *sb)
86 struct omfs_sb_info *sbi = OMFS_SB(sb);
87 struct buffer_head *bh;
88 struct omfs_inode *oi;
90 bh = omfs_bread(sb, inode->i_ino);
94 memset(bh->b_data, 0, sizeof(struct omfs_inode));
96 if (S_ISDIR(inode->i_mode)) {
97 memset(&bh->b_data[OMFS_DIR_START], 0xff,
98 sbi->s_sys_blocksize - OMFS_DIR_START);
100 omfs_make_empty_table(bh, OMFS_EXTENT_START);
102 oi = (struct omfs_inode *) bh->b_data;
103 oi->i_head.h_self = cpu_to_be64(inode->i_ino);
104 oi->i_sibling = ~cpu_to_be64(0ULL);
106 mark_buffer_dirty(bh);
111 static int omfs_add_link(struct dentry *dentry, struct inode *inode)
113 struct inode *dir = d_inode(dentry->d_parent);
114 const char *name = dentry->d_name.name;
115 int namelen = dentry->d_name.len;
116 struct omfs_inode *oi;
117 struct buffer_head *bh;
122 /* just prepend to head of queue in proper bucket */
123 bh = omfs_get_bucket(dir, name, namelen, &ofs);
127 entry = (__be64 *) &bh->b_data[ofs];
128 block = be64_to_cpu(*entry);
129 *entry = cpu_to_be64(inode->i_ino);
130 mark_buffer_dirty(bh);
133 /* now set the sibling and parent pointers on the new inode */
134 bh = omfs_bread(dir->i_sb, inode->i_ino);
138 oi = (struct omfs_inode *) bh->b_data;
139 memcpy(oi->i_name, name, namelen);
140 memset(oi->i_name + namelen, 0, OMFS_NAMELEN - namelen);
141 oi->i_sibling = cpu_to_be64(block);
142 oi->i_parent = cpu_to_be64(dir->i_ino);
143 mark_buffer_dirty(bh);
146 dir->i_ctime = current_time(dir);
148 /* mark affected inodes dirty to rebuild checksums */
149 mark_inode_dirty(dir);
150 mark_inode_dirty(inode);
156 static int omfs_delete_entry(struct dentry *dentry)
158 struct inode *dir = d_inode(dentry->d_parent);
160 const char *name = dentry->d_name.name;
161 int namelen = dentry->d_name.len;
162 struct omfs_inode *oi;
163 struct buffer_head *bh, *bh2;
169 /* delete the proper node in the bucket's linked list */
170 bh = omfs_get_bucket(dir, name, namelen, &ofs);
174 entry = (__be64 *) &bh->b_data[ofs];
175 block = be64_to_cpu(*entry);
177 bh2 = omfs_scan_list(dir, block, name, namelen, &prev);
183 oi = (struct omfs_inode *) bh2->b_data;
184 next = oi->i_sibling;
188 /* found in middle of list, get list ptr */
190 bh = omfs_bread(dir->i_sb, prev);
194 oi = (struct omfs_inode *) bh->b_data;
195 entry = &oi->i_sibling;
199 mark_buffer_dirty(bh);
202 dirty = omfs_iget(dir->i_sb, prev);
203 if (!IS_ERR(dirty)) {
204 mark_inode_dirty(dirty);
216 static int omfs_dir_is_empty(struct inode *inode)
218 int nbuckets = (inode->i_size - OMFS_DIR_START) / 8;
219 struct buffer_head *bh;
223 bh = omfs_bread(inode->i_sb, inode->i_ino);
228 ptr = (u64 *) &bh->b_data[OMFS_DIR_START];
230 for (i = 0; i < nbuckets; i++, ptr++)
238 static int omfs_remove(struct inode *dir, struct dentry *dentry)
240 struct inode *inode = d_inode(dentry);
244 if (S_ISDIR(inode->i_mode) &&
245 !omfs_dir_is_empty(inode))
248 ret = omfs_delete_entry(dentry);
253 mark_inode_dirty(inode);
254 mark_inode_dirty(dir);
258 static int omfs_add_node(struct inode *dir, struct dentry *dentry, umode_t mode)
261 struct inode *inode = omfs_new_inode(dir, mode);
264 return PTR_ERR(inode);
266 err = omfs_make_empty(inode, dir->i_sb);
270 err = omfs_add_link(dentry, inode);
274 d_instantiate(dentry, inode);
282 static int omfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
284 return omfs_add_node(dir, dentry, mode | S_IFDIR);
287 static int omfs_create(struct inode *dir, struct dentry *dentry, umode_t mode,
290 return omfs_add_node(dir, dentry, mode | S_IFREG);
293 static struct dentry *omfs_lookup(struct inode *dir, struct dentry *dentry,
296 struct buffer_head *bh;
297 struct inode *inode = NULL;
299 if (dentry->d_name.len > OMFS_NAMELEN)
300 return ERR_PTR(-ENAMETOOLONG);
302 bh = omfs_find_entry(dir, dentry->d_name.name, dentry->d_name.len);
304 struct omfs_inode *oi = (struct omfs_inode *)bh->b_data;
305 ino_t ino = be64_to_cpu(oi->i_head.h_self);
307 inode = omfs_iget(dir->i_sb, ino);
308 } else if (bh != ERR_PTR(-ENOENT)) {
309 inode = ERR_CAST(bh);
311 return d_splice_alias(inode, dentry);
314 /* sanity check block's self pointer */
315 int omfs_is_bad(struct omfs_sb_info *sbi, struct omfs_header *header,
319 u64 ino = be64_to_cpu(header->h_self);
320 is_bad = ((ino != fsblock) || (ino < sbi->s_root_ino) ||
321 (ino > sbi->s_num_blocks));
324 printk(KERN_WARNING "omfs: bad hash chain detected\n");
329 static bool omfs_fill_chain(struct inode *dir, struct dir_context *ctx,
330 u64 fsblock, int hindex)
332 /* follow chain in this bucket */
333 while (fsblock != ~0) {
334 struct buffer_head *bh = omfs_bread(dir->i_sb, fsblock);
335 struct omfs_inode *oi;
337 unsigned char d_type;
342 oi = (struct omfs_inode *) bh->b_data;
343 if (omfs_is_bad(OMFS_SB(dir->i_sb), &oi->i_head, fsblock)) {
349 fsblock = be64_to_cpu(oi->i_sibling);
351 /* skip visited nodes */
358 d_type = (oi->i_type == OMFS_DIR) ? DT_DIR : DT_REG;
360 if (!dir_emit(ctx, oi->i_name,
361 strnlen(oi->i_name, OMFS_NAMELEN),
372 static int omfs_rename(struct inode *old_dir, struct dentry *old_dentry,
373 struct inode *new_dir, struct dentry *new_dentry,
376 struct inode *new_inode = d_inode(new_dentry);
377 struct inode *old_inode = d_inode(old_dentry);
380 if (flags & ~RENAME_NOREPLACE)
384 /* overwriting existing file/dir */
385 err = omfs_remove(new_dir, new_dentry);
390 /* since omfs locates files by name, we need to unlink _before_
391 * adding the new link or we won't find the old one */
392 err = omfs_delete_entry(old_dentry);
396 mark_inode_dirty(old_dir);
397 err = omfs_add_link(new_dentry, old_inode);
401 old_inode->i_ctime = current_time(old_inode);
402 mark_inode_dirty(old_inode);
407 static int omfs_readdir(struct file *file, struct dir_context *ctx)
409 struct inode *dir = file_inode(file);
410 struct buffer_head *bh;
412 unsigned int hchain, hindex;
418 if (ctx->pos < 1 << 20) {
419 if (!dir_emit_dots(file, ctx))
424 nbuckets = (dir->i_size - OMFS_DIR_START) / 8;
426 /* high 12 bits store bucket + 1 and low 20 bits store hash index */
427 hchain = (ctx->pos >> 20) - 1;
428 hindex = ctx->pos & 0xfffff;
430 bh = omfs_bread(dir->i_sb, dir->i_ino);
434 p = (__be64 *)(bh->b_data + OMFS_DIR_START) + hchain;
436 for (; hchain < nbuckets; hchain++) {
437 __u64 fsblock = be64_to_cpu(*p++);
438 if (!omfs_fill_chain(dir, ctx, fsblock, hindex))
441 ctx->pos = (hchain+2) << 20;
447 const struct inode_operations omfs_dir_inops = {
448 .lookup = omfs_lookup,
450 .rename = omfs_rename,
451 .create = omfs_create,
452 .unlink = omfs_remove,
453 .rmdir = omfs_remove,
456 const struct file_operations omfs_dir_operations = {
457 .read = generic_read_dir,
458 .iterate_shared = omfs_readdir,
459 .llseek = generic_file_llseek,