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0001 // SPDX-License-Identifier: GPL-2.0
0002 /*
0003  *  linux/fs/hfs/bnode.c
0004  *
0005  * Copyright (C) 2001
0006  * Brad Boyer (flar@allandria.com)
0007  * (C) 2003 Ardis Technologies <roman@ardistech.com>
0008  *
0009  * Handle basic btree node operations
0010  */
0011 
0012 #include <linux/pagemap.h>
0013 #include <linux/slab.h>
0014 #include <linux/swap.h>
0015 
0016 #include "btree.h"
0017 
0018 void hfs_bnode_read(struct hfs_bnode *node, void *buf, int off, int len)
0019 {
0020     struct page *page;
0021     int pagenum;
0022     int bytes_read;
0023     int bytes_to_read;
0024     void *vaddr;
0025 
0026     off += node->page_offset;
0027     pagenum = off >> PAGE_SHIFT;
0028     off &= ~PAGE_MASK; /* compute page offset for the first page */
0029 
0030     for (bytes_read = 0; bytes_read < len; bytes_read += bytes_to_read) {
0031         if (pagenum >= node->tree->pages_per_bnode)
0032             break;
0033         page = node->page[pagenum];
0034         bytes_to_read = min_t(int, len - bytes_read, PAGE_SIZE - off);
0035 
0036         vaddr = kmap_atomic(page);
0037         memcpy(buf + bytes_read, vaddr + off, bytes_to_read);
0038         kunmap_atomic(vaddr);
0039 
0040         pagenum++;
0041         off = 0; /* page offset only applies to the first page */
0042     }
0043 }
0044 
0045 u16 hfs_bnode_read_u16(struct hfs_bnode *node, int off)
0046 {
0047     __be16 data;
0048     // optimize later...
0049     hfs_bnode_read(node, &data, off, 2);
0050     return be16_to_cpu(data);
0051 }
0052 
0053 u8 hfs_bnode_read_u8(struct hfs_bnode *node, int off)
0054 {
0055     u8 data;
0056     // optimize later...
0057     hfs_bnode_read(node, &data, off, 1);
0058     return data;
0059 }
0060 
0061 void hfs_bnode_read_key(struct hfs_bnode *node, void *key, int off)
0062 {
0063     struct hfs_btree *tree;
0064     int key_len;
0065 
0066     tree = node->tree;
0067     if (node->type == HFS_NODE_LEAF ||
0068         tree->attributes & HFS_TREE_VARIDXKEYS)
0069         key_len = hfs_bnode_read_u8(node, off) + 1;
0070     else
0071         key_len = tree->max_key_len + 1;
0072 
0073     hfs_bnode_read(node, key, off, key_len);
0074 }
0075 
0076 void hfs_bnode_write(struct hfs_bnode *node, void *buf, int off, int len)
0077 {
0078     struct page *page;
0079 
0080     off += node->page_offset;
0081     page = node->page[0];
0082 
0083     memcpy(kmap(page) + off, buf, len);
0084     kunmap(page);
0085     set_page_dirty(page);
0086 }
0087 
0088 void hfs_bnode_write_u16(struct hfs_bnode *node, int off, u16 data)
0089 {
0090     __be16 v = cpu_to_be16(data);
0091     // optimize later...
0092     hfs_bnode_write(node, &v, off, 2);
0093 }
0094 
0095 void hfs_bnode_write_u8(struct hfs_bnode *node, int off, u8 data)
0096 {
0097     // optimize later...
0098     hfs_bnode_write(node, &data, off, 1);
0099 }
0100 
0101 void hfs_bnode_clear(struct hfs_bnode *node, int off, int len)
0102 {
0103     struct page *page;
0104 
0105     off += node->page_offset;
0106     page = node->page[0];
0107 
0108     memset(kmap(page) + off, 0, len);
0109     kunmap(page);
0110     set_page_dirty(page);
0111 }
0112 
0113 void hfs_bnode_copy(struct hfs_bnode *dst_node, int dst,
0114         struct hfs_bnode *src_node, int src, int len)
0115 {
0116     struct page *src_page, *dst_page;
0117 
0118     hfs_dbg(BNODE_MOD, "copybytes: %u,%u,%u\n", dst, src, len);
0119     if (!len)
0120         return;
0121     src += src_node->page_offset;
0122     dst += dst_node->page_offset;
0123     src_page = src_node->page[0];
0124     dst_page = dst_node->page[0];
0125 
0126     memcpy(kmap(dst_page) + dst, kmap(src_page) + src, len);
0127     kunmap(src_page);
0128     kunmap(dst_page);
0129     set_page_dirty(dst_page);
0130 }
0131 
0132 void hfs_bnode_move(struct hfs_bnode *node, int dst, int src, int len)
0133 {
0134     struct page *page;
0135     void *ptr;
0136 
0137     hfs_dbg(BNODE_MOD, "movebytes: %u,%u,%u\n", dst, src, len);
0138     if (!len)
0139         return;
0140     src += node->page_offset;
0141     dst += node->page_offset;
0142     page = node->page[0];
0143     ptr = kmap(page);
0144     memmove(ptr + dst, ptr + src, len);
0145     kunmap(page);
0146     set_page_dirty(page);
0147 }
0148 
0149 void hfs_bnode_dump(struct hfs_bnode *node)
0150 {
0151     struct hfs_bnode_desc desc;
0152     __be32 cnid;
0153     int i, off, key_off;
0154 
0155     hfs_dbg(BNODE_MOD, "bnode: %d\n", node->this);
0156     hfs_bnode_read(node, &desc, 0, sizeof(desc));
0157     hfs_dbg(BNODE_MOD, "%d, %d, %d, %d, %d\n",
0158         be32_to_cpu(desc.next), be32_to_cpu(desc.prev),
0159         desc.type, desc.height, be16_to_cpu(desc.num_recs));
0160 
0161     off = node->tree->node_size - 2;
0162     for (i = be16_to_cpu(desc.num_recs); i >= 0; off -= 2, i--) {
0163         key_off = hfs_bnode_read_u16(node, off);
0164         hfs_dbg_cont(BNODE_MOD, " %d", key_off);
0165         if (i && node->type == HFS_NODE_INDEX) {
0166             int tmp;
0167 
0168             if (node->tree->attributes & HFS_TREE_VARIDXKEYS)
0169                 tmp = (hfs_bnode_read_u8(node, key_off) | 1) + 1;
0170             else
0171                 tmp = node->tree->max_key_len + 1;
0172             hfs_dbg_cont(BNODE_MOD, " (%d,%d",
0173                      tmp, hfs_bnode_read_u8(node, key_off));
0174             hfs_bnode_read(node, &cnid, key_off + tmp, 4);
0175             hfs_dbg_cont(BNODE_MOD, ",%d)", be32_to_cpu(cnid));
0176         } else if (i && node->type == HFS_NODE_LEAF) {
0177             int tmp;
0178 
0179             tmp = hfs_bnode_read_u8(node, key_off);
0180             hfs_dbg_cont(BNODE_MOD, " (%d)", tmp);
0181         }
0182     }
0183     hfs_dbg_cont(BNODE_MOD, "\n");
0184 }
0185 
0186 void hfs_bnode_unlink(struct hfs_bnode *node)
0187 {
0188     struct hfs_btree *tree;
0189     struct hfs_bnode *tmp;
0190     __be32 cnid;
0191 
0192     tree = node->tree;
0193     if (node->prev) {
0194         tmp = hfs_bnode_find(tree, node->prev);
0195         if (IS_ERR(tmp))
0196             return;
0197         tmp->next = node->next;
0198         cnid = cpu_to_be32(tmp->next);
0199         hfs_bnode_write(tmp, &cnid, offsetof(struct hfs_bnode_desc, next), 4);
0200         hfs_bnode_put(tmp);
0201     } else if (node->type == HFS_NODE_LEAF)
0202         tree->leaf_head = node->next;
0203 
0204     if (node->next) {
0205         tmp = hfs_bnode_find(tree, node->next);
0206         if (IS_ERR(tmp))
0207             return;
0208         tmp->prev = node->prev;
0209         cnid = cpu_to_be32(tmp->prev);
0210         hfs_bnode_write(tmp, &cnid, offsetof(struct hfs_bnode_desc, prev), 4);
0211         hfs_bnode_put(tmp);
0212     } else if (node->type == HFS_NODE_LEAF)
0213         tree->leaf_tail = node->prev;
0214 
0215     // move down?
0216     if (!node->prev && !node->next) {
0217         printk(KERN_DEBUG "hfs_btree_del_level\n");
0218     }
0219     if (!node->parent) {
0220         tree->root = 0;
0221         tree->depth = 0;
0222     }
0223     set_bit(HFS_BNODE_DELETED, &node->flags);
0224 }
0225 
0226 static inline int hfs_bnode_hash(u32 num)
0227 {
0228     num = (num >> 16) + num;
0229     num += num >> 8;
0230     return num & (NODE_HASH_SIZE - 1);
0231 }
0232 
0233 struct hfs_bnode *hfs_bnode_findhash(struct hfs_btree *tree, u32 cnid)
0234 {
0235     struct hfs_bnode *node;
0236 
0237     if (cnid >= tree->node_count) {
0238         pr_err("request for non-existent node %d in B*Tree\n", cnid);
0239         return NULL;
0240     }
0241 
0242     for (node = tree->node_hash[hfs_bnode_hash(cnid)];
0243          node; node = node->next_hash) {
0244         if (node->this == cnid) {
0245             return node;
0246         }
0247     }
0248     return NULL;
0249 }
0250 
0251 static struct hfs_bnode *__hfs_bnode_create(struct hfs_btree *tree, u32 cnid)
0252 {
0253     struct hfs_bnode *node, *node2;
0254     struct address_space *mapping;
0255     struct page *page;
0256     int size, block, i, hash;
0257     loff_t off;
0258 
0259     if (cnid >= tree->node_count) {
0260         pr_err("request for non-existent node %d in B*Tree\n", cnid);
0261         return NULL;
0262     }
0263 
0264     size = sizeof(struct hfs_bnode) + tree->pages_per_bnode *
0265         sizeof(struct page *);
0266     node = kzalloc(size, GFP_KERNEL);
0267     if (!node)
0268         return NULL;
0269     node->tree = tree;
0270     node->this = cnid;
0271     set_bit(HFS_BNODE_NEW, &node->flags);
0272     atomic_set(&node->refcnt, 1);
0273     hfs_dbg(BNODE_REFS, "new_node(%d:%d): 1\n",
0274         node->tree->cnid, node->this);
0275     init_waitqueue_head(&node->lock_wq);
0276     spin_lock(&tree->hash_lock);
0277     node2 = hfs_bnode_findhash(tree, cnid);
0278     if (!node2) {
0279         hash = hfs_bnode_hash(cnid);
0280         node->next_hash = tree->node_hash[hash];
0281         tree->node_hash[hash] = node;
0282         tree->node_hash_cnt++;
0283     } else {
0284         spin_unlock(&tree->hash_lock);
0285         kfree(node);
0286         wait_event(node2->lock_wq, !test_bit(HFS_BNODE_NEW, &node2->flags));
0287         return node2;
0288     }
0289     spin_unlock(&tree->hash_lock);
0290 
0291     mapping = tree->inode->i_mapping;
0292     off = (loff_t)cnid * tree->node_size;
0293     block = off >> PAGE_SHIFT;
0294     node->page_offset = off & ~PAGE_MASK;
0295     for (i = 0; i < tree->pages_per_bnode; i++) {
0296         page = read_mapping_page(mapping, block++, NULL);
0297         if (IS_ERR(page))
0298             goto fail;
0299         node->page[i] = page;
0300     }
0301 
0302     return node;
0303 fail:
0304     set_bit(HFS_BNODE_ERROR, &node->flags);
0305     return node;
0306 }
0307 
0308 void hfs_bnode_unhash(struct hfs_bnode *node)
0309 {
0310     struct hfs_bnode **p;
0311 
0312     hfs_dbg(BNODE_REFS, "remove_node(%d:%d): %d\n",
0313         node->tree->cnid, node->this, atomic_read(&node->refcnt));
0314     for (p = &node->tree->node_hash[hfs_bnode_hash(node->this)];
0315          *p && *p != node; p = &(*p)->next_hash)
0316         ;
0317     BUG_ON(!*p);
0318     *p = node->next_hash;
0319     node->tree->node_hash_cnt--;
0320 }
0321 
0322 /* Load a particular node out of a tree */
0323 struct hfs_bnode *hfs_bnode_find(struct hfs_btree *tree, u32 num)
0324 {
0325     struct hfs_bnode *node;
0326     struct hfs_bnode_desc *desc;
0327     int i, rec_off, off, next_off;
0328     int entry_size, key_size;
0329 
0330     spin_lock(&tree->hash_lock);
0331     node = hfs_bnode_findhash(tree, num);
0332     if (node) {
0333         hfs_bnode_get(node);
0334         spin_unlock(&tree->hash_lock);
0335         wait_event(node->lock_wq, !test_bit(HFS_BNODE_NEW, &node->flags));
0336         if (test_bit(HFS_BNODE_ERROR, &node->flags))
0337             goto node_error;
0338         return node;
0339     }
0340     spin_unlock(&tree->hash_lock);
0341     node = __hfs_bnode_create(tree, num);
0342     if (!node)
0343         return ERR_PTR(-ENOMEM);
0344     if (test_bit(HFS_BNODE_ERROR, &node->flags))
0345         goto node_error;
0346     if (!test_bit(HFS_BNODE_NEW, &node->flags))
0347         return node;
0348 
0349     desc = (struct hfs_bnode_desc *)(kmap(node->page[0]) + node->page_offset);
0350     node->prev = be32_to_cpu(desc->prev);
0351     node->next = be32_to_cpu(desc->next);
0352     node->num_recs = be16_to_cpu(desc->num_recs);
0353     node->type = desc->type;
0354     node->height = desc->height;
0355     kunmap(node->page[0]);
0356 
0357     switch (node->type) {
0358     case HFS_NODE_HEADER:
0359     case HFS_NODE_MAP:
0360         if (node->height != 0)
0361             goto node_error;
0362         break;
0363     case HFS_NODE_LEAF:
0364         if (node->height != 1)
0365             goto node_error;
0366         break;
0367     case HFS_NODE_INDEX:
0368         if (node->height <= 1 || node->height > tree->depth)
0369             goto node_error;
0370         break;
0371     default:
0372         goto node_error;
0373     }
0374 
0375     rec_off = tree->node_size - 2;
0376     off = hfs_bnode_read_u16(node, rec_off);
0377     if (off != sizeof(struct hfs_bnode_desc))
0378         goto node_error;
0379     for (i = 1; i <= node->num_recs; off = next_off, i++) {
0380         rec_off -= 2;
0381         next_off = hfs_bnode_read_u16(node, rec_off);
0382         if (next_off <= off ||
0383             next_off > tree->node_size ||
0384             next_off & 1)
0385             goto node_error;
0386         entry_size = next_off - off;
0387         if (node->type != HFS_NODE_INDEX &&
0388             node->type != HFS_NODE_LEAF)
0389             continue;
0390         key_size = hfs_bnode_read_u8(node, off) + 1;
0391         if (key_size >= entry_size /*|| key_size & 1*/)
0392             goto node_error;
0393     }
0394     clear_bit(HFS_BNODE_NEW, &node->flags);
0395     wake_up(&node->lock_wq);
0396     return node;
0397 
0398 node_error:
0399     set_bit(HFS_BNODE_ERROR, &node->flags);
0400     clear_bit(HFS_BNODE_NEW, &node->flags);
0401     wake_up(&node->lock_wq);
0402     hfs_bnode_put(node);
0403     return ERR_PTR(-EIO);
0404 }
0405 
0406 void hfs_bnode_free(struct hfs_bnode *node)
0407 {
0408     int i;
0409 
0410     for (i = 0; i < node->tree->pages_per_bnode; i++)
0411         if (node->page[i])
0412             put_page(node->page[i]);
0413     kfree(node);
0414 }
0415 
0416 struct hfs_bnode *hfs_bnode_create(struct hfs_btree *tree, u32 num)
0417 {
0418     struct hfs_bnode *node;
0419     struct page **pagep;
0420     int i;
0421 
0422     spin_lock(&tree->hash_lock);
0423     node = hfs_bnode_findhash(tree, num);
0424     spin_unlock(&tree->hash_lock);
0425     if (node) {
0426         pr_crit("new node %u already hashed?\n", num);
0427         WARN_ON(1);
0428         return node;
0429     }
0430     node = __hfs_bnode_create(tree, num);
0431     if (!node)
0432         return ERR_PTR(-ENOMEM);
0433     if (test_bit(HFS_BNODE_ERROR, &node->flags)) {
0434         hfs_bnode_put(node);
0435         return ERR_PTR(-EIO);
0436     }
0437 
0438     pagep = node->page;
0439     memset(kmap(*pagep) + node->page_offset, 0,
0440            min((int)PAGE_SIZE, (int)tree->node_size));
0441     set_page_dirty(*pagep);
0442     kunmap(*pagep);
0443     for (i = 1; i < tree->pages_per_bnode; i++) {
0444         memset(kmap(*++pagep), 0, PAGE_SIZE);
0445         set_page_dirty(*pagep);
0446         kunmap(*pagep);
0447     }
0448     clear_bit(HFS_BNODE_NEW, &node->flags);
0449     wake_up(&node->lock_wq);
0450 
0451     return node;
0452 }
0453 
0454 void hfs_bnode_get(struct hfs_bnode *node)
0455 {
0456     if (node) {
0457         atomic_inc(&node->refcnt);
0458         hfs_dbg(BNODE_REFS, "get_node(%d:%d): %d\n",
0459             node->tree->cnid, node->this,
0460             atomic_read(&node->refcnt));
0461     }
0462 }
0463 
0464 /* Dispose of resources used by a node */
0465 void hfs_bnode_put(struct hfs_bnode *node)
0466 {
0467     if (node) {
0468         struct hfs_btree *tree = node->tree;
0469         int i;
0470 
0471         hfs_dbg(BNODE_REFS, "put_node(%d:%d): %d\n",
0472             node->tree->cnid, node->this,
0473             atomic_read(&node->refcnt));
0474         BUG_ON(!atomic_read(&node->refcnt));
0475         if (!atomic_dec_and_lock(&node->refcnt, &tree->hash_lock))
0476             return;
0477         for (i = 0; i < tree->pages_per_bnode; i++) {
0478             if (!node->page[i])
0479                 continue;
0480             mark_page_accessed(node->page[i]);
0481         }
0482 
0483         if (test_bit(HFS_BNODE_DELETED, &node->flags)) {
0484             hfs_bnode_unhash(node);
0485             spin_unlock(&tree->hash_lock);
0486             hfs_bmap_free(node);
0487             hfs_bnode_free(node);
0488             return;
0489         }
0490         spin_unlock(&tree->hash_lock);
0491     }
0492 }
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