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![Fabio M. De Francesco](/assets/img/avatar_default.png)
kmap() is being deprecated in favor of kmap_local_page(). Two main problems with kmap(): (1) It comes with an overhead as mapping space is restricted and protected by a global lock for synchronization and (2) it also requires global TLB invalidation when the kmap's pool wraps and it might block when the mapping space is fully utilized until a slot becomes available. With kmap_local_page() the mappings are per thread, CPU local, can take page faults, and can be called from any context (including interrupts). It is faster than kmap() in kernels with HIGHMEM enabled. Furthermore, the tasks can be preempted and, when they are scheduled to run again, the kernel virtual addresses are restored and still valid. Since its use in btree.c is safe everywhere, it should be preferred. Therefore, replace kmap() with kmap_local_page() in btree.c. Where possible, use the suited standard helpers (memzero_page(), memcpy_page()) instead of open coding kmap_local_page() plus memset() or memcpy(). Tested in a QEMU/KVM x86_32 VM, 6GB RAM, booting a kernel with HIGHMEM64GB enabled. Link: https://lkml.kernel.org/r/20220821180400.8198-4-fmdefrancesco@gmail.com Signed-off-by: Fabio M. De Francesco <fmdefrancesco@gmail.com> Suggested-by: Ira Weiny <ira.weiny@intel.com> Reviewed-by: Viacheslav Dubeyko <slava@dubeyko.com> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Chaitanya Kulkarni <kch@nvidia.com> Cc: Christian Brauner (Microsoft) <brauner@kernel.org> Cc: Damien Le Moal <damien.lemoal@opensource.wdc.com> Cc: Jeff Layton <jlayton@kernel.org> Cc: Jens Axboe <axboe@kernel.dk> Cc: Kees Cook <keescook@chromium.org> Cc: Martin K. Petersen <martin.petersen@oracle.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Roman Gushchin <roman.gushchin@linux.dev> Cc: Theodore Ts'o <tytso@mit.edu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
383 lines
9 KiB
C
383 lines
9 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* linux/fs/hfs/btree.c
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*
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* Copyright (C) 2001
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* Brad Boyer (flar@allandria.com)
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* (C) 2003 Ardis Technologies <roman@ardistech.com>
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*
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* Handle opening/closing btree
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*/
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#include <linux/pagemap.h>
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#include <linux/slab.h>
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#include <linux/log2.h>
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#include "btree.h"
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/* Get a reference to a B*Tree and do some initial checks */
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struct hfs_btree *hfs_btree_open(struct super_block *sb, u32 id, btree_keycmp keycmp)
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{
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struct hfs_btree *tree;
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struct hfs_btree_header_rec *head;
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struct address_space *mapping;
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struct page *page;
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unsigned int size;
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tree = kzalloc(sizeof(*tree), GFP_KERNEL);
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if (!tree)
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return NULL;
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mutex_init(&tree->tree_lock);
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spin_lock_init(&tree->hash_lock);
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/* Set the correct compare function */
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tree->sb = sb;
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tree->cnid = id;
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tree->keycmp = keycmp;
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tree->inode = iget_locked(sb, id);
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if (!tree->inode)
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goto free_tree;
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BUG_ON(!(tree->inode->i_state & I_NEW));
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{
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struct hfs_mdb *mdb = HFS_SB(sb)->mdb;
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HFS_I(tree->inode)->flags = 0;
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mutex_init(&HFS_I(tree->inode)->extents_lock);
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switch (id) {
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case HFS_EXT_CNID:
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hfs_inode_read_fork(tree->inode, mdb->drXTExtRec, mdb->drXTFlSize,
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mdb->drXTFlSize, be32_to_cpu(mdb->drXTClpSiz));
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if (HFS_I(tree->inode)->alloc_blocks >
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HFS_I(tree->inode)->first_blocks) {
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pr_err("invalid btree extent records\n");
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unlock_new_inode(tree->inode);
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goto free_inode;
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}
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tree->inode->i_mapping->a_ops = &hfs_btree_aops;
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break;
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case HFS_CAT_CNID:
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hfs_inode_read_fork(tree->inode, mdb->drCTExtRec, mdb->drCTFlSize,
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mdb->drCTFlSize, be32_to_cpu(mdb->drCTClpSiz));
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if (!HFS_I(tree->inode)->first_blocks) {
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pr_err("invalid btree extent records (0 size)\n");
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unlock_new_inode(tree->inode);
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goto free_inode;
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}
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tree->inode->i_mapping->a_ops = &hfs_btree_aops;
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break;
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default:
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BUG();
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}
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}
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unlock_new_inode(tree->inode);
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mapping = tree->inode->i_mapping;
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page = read_mapping_page(mapping, 0, NULL);
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if (IS_ERR(page))
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goto free_inode;
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/* Load the header */
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head = (struct hfs_btree_header_rec *)(kmap_local_page(page) +
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sizeof(struct hfs_bnode_desc));
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tree->root = be32_to_cpu(head->root);
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tree->leaf_count = be32_to_cpu(head->leaf_count);
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tree->leaf_head = be32_to_cpu(head->leaf_head);
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tree->leaf_tail = be32_to_cpu(head->leaf_tail);
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tree->node_count = be32_to_cpu(head->node_count);
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tree->free_nodes = be32_to_cpu(head->free_nodes);
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tree->attributes = be32_to_cpu(head->attributes);
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tree->node_size = be16_to_cpu(head->node_size);
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tree->max_key_len = be16_to_cpu(head->max_key_len);
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tree->depth = be16_to_cpu(head->depth);
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size = tree->node_size;
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if (!is_power_of_2(size))
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goto fail_page;
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if (!tree->node_count)
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goto fail_page;
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switch (id) {
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case HFS_EXT_CNID:
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if (tree->max_key_len != HFS_MAX_EXT_KEYLEN) {
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pr_err("invalid extent max_key_len %d\n",
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tree->max_key_len);
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goto fail_page;
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}
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break;
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case HFS_CAT_CNID:
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if (tree->max_key_len != HFS_MAX_CAT_KEYLEN) {
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pr_err("invalid catalog max_key_len %d\n",
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tree->max_key_len);
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goto fail_page;
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}
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break;
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default:
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BUG();
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}
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tree->node_size_shift = ffs(size) - 1;
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tree->pages_per_bnode = (tree->node_size + PAGE_SIZE - 1) >> PAGE_SHIFT;
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kunmap_local(head);
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put_page(page);
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return tree;
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fail_page:
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kunmap_local(head);
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put_page(page);
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free_inode:
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tree->inode->i_mapping->a_ops = &hfs_aops;
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iput(tree->inode);
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free_tree:
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kfree(tree);
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return NULL;
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}
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/* Release resources used by a btree */
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void hfs_btree_close(struct hfs_btree *tree)
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{
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struct hfs_bnode *node;
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int i;
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if (!tree)
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return;
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for (i = 0; i < NODE_HASH_SIZE; i++) {
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while ((node = tree->node_hash[i])) {
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tree->node_hash[i] = node->next_hash;
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if (atomic_read(&node->refcnt))
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pr_err("node %d:%d still has %d user(s)!\n",
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node->tree->cnid, node->this,
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atomic_read(&node->refcnt));
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hfs_bnode_free(node);
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tree->node_hash_cnt--;
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}
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}
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iput(tree->inode);
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kfree(tree);
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}
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void hfs_btree_write(struct hfs_btree *tree)
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{
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struct hfs_btree_header_rec *head;
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struct hfs_bnode *node;
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struct page *page;
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node = hfs_bnode_find(tree, 0);
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if (IS_ERR(node))
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/* panic? */
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return;
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/* Load the header */
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page = node->page[0];
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head = (struct hfs_btree_header_rec *)(kmap_local_page(page) +
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sizeof(struct hfs_bnode_desc));
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head->root = cpu_to_be32(tree->root);
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head->leaf_count = cpu_to_be32(tree->leaf_count);
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head->leaf_head = cpu_to_be32(tree->leaf_head);
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head->leaf_tail = cpu_to_be32(tree->leaf_tail);
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head->node_count = cpu_to_be32(tree->node_count);
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head->free_nodes = cpu_to_be32(tree->free_nodes);
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head->attributes = cpu_to_be32(tree->attributes);
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head->depth = cpu_to_be16(tree->depth);
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kunmap_local(head);
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set_page_dirty(page);
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hfs_bnode_put(node);
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}
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static struct hfs_bnode *hfs_bmap_new_bmap(struct hfs_bnode *prev, u32 idx)
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{
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struct hfs_btree *tree = prev->tree;
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struct hfs_bnode *node;
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struct hfs_bnode_desc desc;
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__be32 cnid;
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node = hfs_bnode_create(tree, idx);
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if (IS_ERR(node))
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return node;
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if (!tree->free_nodes)
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panic("FIXME!!!");
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tree->free_nodes--;
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prev->next = idx;
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cnid = cpu_to_be32(idx);
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hfs_bnode_write(prev, &cnid, offsetof(struct hfs_bnode_desc, next), 4);
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node->type = HFS_NODE_MAP;
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node->num_recs = 1;
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hfs_bnode_clear(node, 0, tree->node_size);
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desc.next = 0;
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desc.prev = 0;
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desc.type = HFS_NODE_MAP;
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desc.height = 0;
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desc.num_recs = cpu_to_be16(1);
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desc.reserved = 0;
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hfs_bnode_write(node, &desc, 0, sizeof(desc));
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hfs_bnode_write_u16(node, 14, 0x8000);
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hfs_bnode_write_u16(node, tree->node_size - 2, 14);
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hfs_bnode_write_u16(node, tree->node_size - 4, tree->node_size - 6);
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return node;
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}
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/* Make sure @tree has enough space for the @rsvd_nodes */
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int hfs_bmap_reserve(struct hfs_btree *tree, int rsvd_nodes)
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{
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struct inode *inode = tree->inode;
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u32 count;
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int res;
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while (tree->free_nodes < rsvd_nodes) {
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res = hfs_extend_file(inode);
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if (res)
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return res;
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HFS_I(inode)->phys_size = inode->i_size =
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(loff_t)HFS_I(inode)->alloc_blocks *
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HFS_SB(tree->sb)->alloc_blksz;
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HFS_I(inode)->fs_blocks = inode->i_size >>
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tree->sb->s_blocksize_bits;
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inode_set_bytes(inode, inode->i_size);
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count = inode->i_size >> tree->node_size_shift;
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tree->free_nodes += count - tree->node_count;
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tree->node_count = count;
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}
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return 0;
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}
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struct hfs_bnode *hfs_bmap_alloc(struct hfs_btree *tree)
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{
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struct hfs_bnode *node, *next_node;
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struct page **pagep;
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u32 nidx, idx;
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unsigned off;
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u16 off16;
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u16 len;
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u8 *data, byte, m;
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int i, res;
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res = hfs_bmap_reserve(tree, 1);
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if (res)
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return ERR_PTR(res);
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nidx = 0;
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node = hfs_bnode_find(tree, nidx);
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if (IS_ERR(node))
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return node;
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len = hfs_brec_lenoff(node, 2, &off16);
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off = off16;
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off += node->page_offset;
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pagep = node->page + (off >> PAGE_SHIFT);
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data = kmap_local_page(*pagep);
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off &= ~PAGE_MASK;
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idx = 0;
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for (;;) {
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while (len) {
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byte = data[off];
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if (byte != 0xff) {
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for (m = 0x80, i = 0; i < 8; m >>= 1, i++) {
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if (!(byte & m)) {
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idx += i;
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data[off] |= m;
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set_page_dirty(*pagep);
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kunmap_local(data);
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tree->free_nodes--;
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mark_inode_dirty(tree->inode);
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hfs_bnode_put(node);
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return hfs_bnode_create(tree, idx);
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}
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}
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}
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if (++off >= PAGE_SIZE) {
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kunmap_local(data);
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data = kmap_local_page(*++pagep);
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off = 0;
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}
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idx += 8;
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len--;
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}
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kunmap_local(data);
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nidx = node->next;
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if (!nidx) {
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printk(KERN_DEBUG "create new bmap node...\n");
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next_node = hfs_bmap_new_bmap(node, idx);
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} else
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next_node = hfs_bnode_find(tree, nidx);
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hfs_bnode_put(node);
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if (IS_ERR(next_node))
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return next_node;
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node = next_node;
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len = hfs_brec_lenoff(node, 0, &off16);
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off = off16;
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off += node->page_offset;
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pagep = node->page + (off >> PAGE_SHIFT);
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data = kmap_local_page(*pagep);
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off &= ~PAGE_MASK;
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}
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}
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void hfs_bmap_free(struct hfs_bnode *node)
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{
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struct hfs_btree *tree;
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struct page *page;
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u16 off, len;
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u32 nidx;
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u8 *data, byte, m;
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hfs_dbg(BNODE_MOD, "btree_free_node: %u\n", node->this);
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tree = node->tree;
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nidx = node->this;
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node = hfs_bnode_find(tree, 0);
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if (IS_ERR(node))
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return;
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len = hfs_brec_lenoff(node, 2, &off);
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while (nidx >= len * 8) {
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u32 i;
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nidx -= len * 8;
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i = node->next;
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if (!i) {
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/* panic */;
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pr_crit("unable to free bnode %u. bmap not found!\n",
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node->this);
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hfs_bnode_put(node);
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return;
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}
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hfs_bnode_put(node);
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node = hfs_bnode_find(tree, i);
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if (IS_ERR(node))
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return;
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if (node->type != HFS_NODE_MAP) {
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/* panic */;
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pr_crit("invalid bmap found! (%u,%d)\n",
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node->this, node->type);
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hfs_bnode_put(node);
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return;
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}
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len = hfs_brec_lenoff(node, 0, &off);
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}
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off += node->page_offset + nidx / 8;
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page = node->page[off >> PAGE_SHIFT];
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data = kmap_local_page(page);
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off &= ~PAGE_MASK;
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m = 1 << (~nidx & 7);
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byte = data[off];
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if (!(byte & m)) {
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pr_crit("trying to free free bnode %u(%d)\n",
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node->this, node->type);
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kunmap_local(data);
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hfs_bnode_put(node);
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return;
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}
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data[off] = byte & ~m;
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set_page_dirty(page);
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kunmap_local(data);
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hfs_bnode_put(node);
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tree->free_nodes++;
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mark_inode_dirty(tree->inode);
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}
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