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784 lines
22 KiB
784 lines
22 KiB
/* |
|
* linux/fs/befs/btree.c |
|
* |
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* Copyright (C) 2001-2002 Will Dyson <[email protected]> |
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* |
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* Licensed under the GNU GPL. See the file COPYING for details. |
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* |
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* 2002-02-05: Sergey S. Kostyliov added binary search within |
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* btree nodes. |
|
* |
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* Many thanks to: |
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* |
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* Dominic Giampaolo, author of "Practical File System |
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* Design with the Be File System", for such a helpful book. |
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* |
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* Marcus J. Ranum, author of the b+tree package in |
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* comp.sources.misc volume 10. This code is not copied from that |
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* work, but it is partially based on it. |
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* |
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* Makoto Kato, author of the original BeFS for linux filesystem |
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* driver. |
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*/ |
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|
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#include <linux/kernel.h> |
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#include <linux/string.h> |
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#include <linux/slab.h> |
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#include <linux/mm.h> |
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#include <linux/buffer_head.h> |
|
|
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#include "befs.h" |
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#include "btree.h" |
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#include "datastream.h" |
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|
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/* |
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* The btree functions in this file are built on top of the |
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* datastream.c interface, which is in turn built on top of the |
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* io.c interface. |
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*/ |
|
|
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/* Befs B+tree structure: |
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* |
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* The first thing in the tree is the tree superblock. It tells you |
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* all kinds of useful things about the tree, like where the rootnode |
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* is located, and the size of the nodes (always 1024 with current version |
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* of BeOS). |
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* |
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* The rest of the tree consists of a series of nodes. Nodes contain a header |
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* (struct befs_btree_nodehead), the packed key data, an array of shorts |
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* containing the ending offsets for each of the keys, and an array of |
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* befs_off_t values. In interior nodes, the keys are the ending keys for |
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* the childnode they point to, and the values are offsets into the |
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* datastream containing the tree. |
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*/ |
|
|
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/* Note: |
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* |
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* The book states 2 confusing things about befs b+trees. First, |
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* it states that the overflow field of node headers is used by internal nodes |
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* to point to another node that "effectively continues this one". Here is what |
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* I believe that means. Each key in internal nodes points to another node that |
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* contains key values less than itself. Inspection reveals that the last key |
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* in the internal node is not the last key in the index. Keys that are |
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* greater than the last key in the internal node go into the overflow node. |
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* I imagine there is a performance reason for this. |
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* |
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* Second, it states that the header of a btree node is sufficient to |
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* distinguish internal nodes from leaf nodes. Without saying exactly how. |
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* After figuring out the first, it becomes obvious that internal nodes have |
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* overflow nodes and leafnodes do not. |
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*/ |
|
|
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/* |
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* Currently, this code is only good for directory B+trees. |
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* In order to be used for other BFS indexes, it needs to be extended to handle |
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* duplicate keys and non-string keytypes (int32, int64, float, double). |
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*/ |
|
|
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/* |
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* In memory structure of each btree node |
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*/ |
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struct befs_btree_node { |
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befs_host_btree_nodehead head; /* head of node converted to cpu byteorder */ |
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struct buffer_head *bh; |
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befs_btree_nodehead *od_node; /* on disk node */ |
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}; |
|
|
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/* local constants */ |
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static const befs_off_t BEFS_BT_INVAL = 0xffffffffffffffffULL; |
|
|
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/* local functions */ |
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static int befs_btree_seekleaf(struct super_block *sb, const befs_data_stream *ds, |
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befs_btree_super * bt_super, |
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struct befs_btree_node *this_node, |
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befs_off_t * node_off); |
|
|
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static int befs_bt_read_super(struct super_block *sb, const befs_data_stream *ds, |
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befs_btree_super * sup); |
|
|
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static int befs_bt_read_node(struct super_block *sb, const befs_data_stream *ds, |
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struct befs_btree_node *node, |
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befs_off_t node_off); |
|
|
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static int befs_leafnode(struct befs_btree_node *node); |
|
|
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static fs16 *befs_bt_keylen_index(struct befs_btree_node *node); |
|
|
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static fs64 *befs_bt_valarray(struct befs_btree_node *node); |
|
|
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static char *befs_bt_keydata(struct befs_btree_node *node); |
|
|
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static int befs_find_key(struct super_block *sb, |
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struct befs_btree_node *node, |
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const char *findkey, befs_off_t * value); |
|
|
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static char *befs_bt_get_key(struct super_block *sb, |
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struct befs_btree_node *node, |
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int index, u16 * keylen); |
|
|
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static int befs_compare_strings(const void *key1, int keylen1, |
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const void *key2, int keylen2); |
|
|
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/** |
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* befs_bt_read_super() - read in btree superblock convert to cpu byteorder |
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* @sb: Filesystem superblock |
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* @ds: Datastream to read from |
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* @sup: Buffer in which to place the btree superblock |
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* |
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* Calls befs_read_datastream to read in the btree superblock and |
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* makes sure it is in cpu byteorder, byteswapping if necessary. |
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* Return: BEFS_OK on success and if *@sup contains the btree superblock in cpu |
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* byte order. Otherwise return BEFS_ERR on error. |
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*/ |
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static int |
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befs_bt_read_super(struct super_block *sb, const befs_data_stream *ds, |
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befs_btree_super * sup) |
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{ |
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struct buffer_head *bh; |
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befs_disk_btree_super *od_sup; |
|
|
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befs_debug(sb, "---> %s", __func__); |
|
|
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bh = befs_read_datastream(sb, ds, 0, NULL); |
|
|
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if (!bh) { |
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befs_error(sb, "Couldn't read index header."); |
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goto error; |
|
} |
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od_sup = (befs_disk_btree_super *) bh->b_data; |
|
befs_dump_index_entry(sb, od_sup); |
|
|
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sup->magic = fs32_to_cpu(sb, od_sup->magic); |
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sup->node_size = fs32_to_cpu(sb, od_sup->node_size); |
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sup->max_depth = fs32_to_cpu(sb, od_sup->max_depth); |
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sup->data_type = fs32_to_cpu(sb, od_sup->data_type); |
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sup->root_node_ptr = fs64_to_cpu(sb, od_sup->root_node_ptr); |
|
|
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brelse(bh); |
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if (sup->magic != BEFS_BTREE_MAGIC) { |
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befs_error(sb, "Index header has bad magic."); |
|
goto error; |
|
} |
|
|
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befs_debug(sb, "<--- %s", __func__); |
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return BEFS_OK; |
|
|
|
error: |
|
befs_debug(sb, "<--- %s ERROR", __func__); |
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return BEFS_ERR; |
|
} |
|
|
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/** |
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* befs_bt_read_node - read in btree node and convert to cpu byteorder |
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* @sb: Filesystem superblock |
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* @ds: Datastream to read from |
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* @node: Buffer in which to place the btree node |
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* @node_off: Starting offset (in bytes) of the node in @ds |
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* |
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* Calls befs_read_datastream to read in the indicated btree node and |
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* makes sure its header fields are in cpu byteorder, byteswapping if |
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* necessary. |
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* Note: node->bh must be NULL when this function is called the first time. |
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* Don't forget brelse(node->bh) after last call. |
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* |
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* On success, returns BEFS_OK and *@node contains the btree node that |
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* starts at @node_off, with the node->head fields in cpu byte order. |
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* |
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* On failure, BEFS_ERR is returned. |
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*/ |
|
|
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static int |
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befs_bt_read_node(struct super_block *sb, const befs_data_stream *ds, |
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struct befs_btree_node *node, befs_off_t node_off) |
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{ |
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uint off = 0; |
|
|
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befs_debug(sb, "---> %s", __func__); |
|
|
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if (node->bh) |
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brelse(node->bh); |
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|
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node->bh = befs_read_datastream(sb, ds, node_off, &off); |
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if (!node->bh) { |
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befs_error(sb, "%s failed to read " |
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"node at %llu", __func__, node_off); |
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befs_debug(sb, "<--- %s ERROR", __func__); |
|
|
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return BEFS_ERR; |
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} |
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node->od_node = |
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(befs_btree_nodehead *) ((void *) node->bh->b_data + off); |
|
|
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befs_dump_index_node(sb, node->od_node); |
|
|
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node->head.left = fs64_to_cpu(sb, node->od_node->left); |
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node->head.right = fs64_to_cpu(sb, node->od_node->right); |
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node->head.overflow = fs64_to_cpu(sb, node->od_node->overflow); |
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node->head.all_key_count = |
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fs16_to_cpu(sb, node->od_node->all_key_count); |
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node->head.all_key_length = |
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fs16_to_cpu(sb, node->od_node->all_key_length); |
|
|
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befs_debug(sb, "<--- %s", __func__); |
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return BEFS_OK; |
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} |
|
|
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/** |
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* befs_btree_find - Find a key in a befs B+tree |
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* @sb: Filesystem superblock |
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* @ds: Datastream containing btree |
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* @key: Key string to lookup in btree |
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* @value: Value stored with @key |
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* |
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* On success, returns BEFS_OK and sets *@value to the value stored |
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* with @key (usually the disk block number of an inode). |
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* |
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* On failure, returns BEFS_ERR or BEFS_BT_NOT_FOUND. |
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* |
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* Algorithm: |
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* Read the superblock and rootnode of the b+tree. |
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* Drill down through the interior nodes using befs_find_key(). |
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* Once at the correct leaf node, use befs_find_key() again to get the |
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* actual value stored with the key. |
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*/ |
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int |
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befs_btree_find(struct super_block *sb, const befs_data_stream *ds, |
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const char *key, befs_off_t * value) |
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{ |
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struct befs_btree_node *this_node; |
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befs_btree_super bt_super; |
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befs_off_t node_off; |
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int res; |
|
|
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befs_debug(sb, "---> %s Key: %s", __func__, key); |
|
|
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if (befs_bt_read_super(sb, ds, &bt_super) != BEFS_OK) { |
|
befs_error(sb, |
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"befs_btree_find() failed to read index superblock"); |
|
goto error; |
|
} |
|
|
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this_node = kmalloc(sizeof(struct befs_btree_node), |
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GFP_NOFS); |
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if (!this_node) { |
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befs_error(sb, "befs_btree_find() failed to allocate %zu " |
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"bytes of memory", sizeof(struct befs_btree_node)); |
|
goto error; |
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} |
|
|
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this_node->bh = NULL; |
|
|
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/* read in root node */ |
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node_off = bt_super.root_node_ptr; |
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if (befs_bt_read_node(sb, ds, this_node, node_off) != BEFS_OK) { |
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befs_error(sb, "befs_btree_find() failed to read " |
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"node at %llu", node_off); |
|
goto error_alloc; |
|
} |
|
|
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while (!befs_leafnode(this_node)) { |
|
res = befs_find_key(sb, this_node, key, &node_off); |
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/* if no key set, try the overflow node */ |
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if (res == BEFS_BT_OVERFLOW) |
|
node_off = this_node->head.overflow; |
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if (befs_bt_read_node(sb, ds, this_node, node_off) != BEFS_OK) { |
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befs_error(sb, "befs_btree_find() failed to read " |
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"node at %llu", node_off); |
|
goto error_alloc; |
|
} |
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} |
|
|
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/* at a leaf node now, check if it is correct */ |
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res = befs_find_key(sb, this_node, key, value); |
|
|
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brelse(this_node->bh); |
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kfree(this_node); |
|
|
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if (res != BEFS_BT_MATCH) { |
|
befs_error(sb, "<--- %s Key %s not found", __func__, key); |
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befs_debug(sb, "<--- %s ERROR", __func__); |
|
*value = 0; |
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return BEFS_BT_NOT_FOUND; |
|
} |
|
befs_debug(sb, "<--- %s Found key %s, value %llu", __func__, |
|
key, *value); |
|
return BEFS_OK; |
|
|
|
error_alloc: |
|
kfree(this_node); |
|
error: |
|
*value = 0; |
|
befs_debug(sb, "<--- %s ERROR", __func__); |
|
return BEFS_ERR; |
|
} |
|
|
|
/** |
|
* befs_find_key - Search for a key within a node |
|
* @sb: Filesystem superblock |
|
* @node: Node to find the key within |
|
* @findkey: Keystring to search for |
|
* @value: If key is found, the value stored with the key is put here |
|
* |
|
* Finds exact match if one exists, and returns BEFS_BT_MATCH. |
|
* If there is no match and node's value array is too small for key, return |
|
* BEFS_BT_OVERFLOW. |
|
* If no match and node should countain this key, return BEFS_BT_NOT_FOUND. |
|
* |
|
* Uses binary search instead of a linear. |
|
*/ |
|
static int |
|
befs_find_key(struct super_block *sb, struct befs_btree_node *node, |
|
const char *findkey, befs_off_t * value) |
|
{ |
|
int first, last, mid; |
|
int eq; |
|
u16 keylen; |
|
int findkey_len; |
|
char *thiskey; |
|
fs64 *valarray; |
|
|
|
befs_debug(sb, "---> %s %s", __func__, findkey); |
|
|
|
findkey_len = strlen(findkey); |
|
|
|
/* if node can not contain key, just skip this node */ |
|
last = node->head.all_key_count - 1; |
|
thiskey = befs_bt_get_key(sb, node, last, &keylen); |
|
|
|
eq = befs_compare_strings(thiskey, keylen, findkey, findkey_len); |
|
if (eq < 0) { |
|
befs_debug(sb, "<--- node can't contain %s", findkey); |
|
return BEFS_BT_OVERFLOW; |
|
} |
|
|
|
valarray = befs_bt_valarray(node); |
|
|
|
/* simple binary search */ |
|
first = 0; |
|
mid = 0; |
|
while (last >= first) { |
|
mid = (last + first) / 2; |
|
befs_debug(sb, "first: %d, last: %d, mid: %d", first, last, |
|
mid); |
|
thiskey = befs_bt_get_key(sb, node, mid, &keylen); |
|
eq = befs_compare_strings(thiskey, keylen, findkey, |
|
findkey_len); |
|
|
|
if (eq == 0) { |
|
befs_debug(sb, "<--- %s found %s at %d", |
|
__func__, thiskey, mid); |
|
|
|
*value = fs64_to_cpu(sb, valarray[mid]); |
|
return BEFS_BT_MATCH; |
|
} |
|
if (eq > 0) |
|
last = mid - 1; |
|
else |
|
first = mid + 1; |
|
} |
|
|
|
/* return an existing value so caller can arrive to a leaf node */ |
|
if (eq < 0) |
|
*value = fs64_to_cpu(sb, valarray[mid + 1]); |
|
else |
|
*value = fs64_to_cpu(sb, valarray[mid]); |
|
befs_error(sb, "<--- %s %s not found", __func__, findkey); |
|
befs_debug(sb, "<--- %s ERROR", __func__); |
|
return BEFS_BT_NOT_FOUND; |
|
} |
|
|
|
/** |
|
* befs_btree_read - Traverse leafnodes of a btree |
|
* @sb: Filesystem superblock |
|
* @ds: Datastream containing btree |
|
* @key_no: Key number (alphabetical order) of key to read |
|
* @bufsize: Size of the buffer to return key in |
|
* @keybuf: Pointer to a buffer to put the key in |
|
* @keysize: Length of the returned key |
|
* @value: Value stored with the returned key |
|
* |
|
* Here's how it works: Key_no is the index of the key/value pair to |
|
* return in keybuf/value. |
|
* Bufsize is the size of keybuf (BEFS_NAME_LEN+1 is a good size). Keysize is |
|
* the number of characters in the key (just a convenience). |
|
* |
|
* Algorithm: |
|
* Get the first leafnode of the tree. See if the requested key is in that |
|
* node. If not, follow the node->right link to the next leafnode. Repeat |
|
* until the (key_no)th key is found or the tree is out of keys. |
|
*/ |
|
int |
|
befs_btree_read(struct super_block *sb, const befs_data_stream *ds, |
|
loff_t key_no, size_t bufsize, char *keybuf, size_t * keysize, |
|
befs_off_t * value) |
|
{ |
|
struct befs_btree_node *this_node; |
|
befs_btree_super bt_super; |
|
befs_off_t node_off; |
|
int cur_key; |
|
fs64 *valarray; |
|
char *keystart; |
|
u16 keylen; |
|
int res; |
|
|
|
uint key_sum = 0; |
|
|
|
befs_debug(sb, "---> %s", __func__); |
|
|
|
if (befs_bt_read_super(sb, ds, &bt_super) != BEFS_OK) { |
|
befs_error(sb, |
|
"befs_btree_read() failed to read index superblock"); |
|
goto error; |
|
} |
|
|
|
this_node = kmalloc(sizeof(struct befs_btree_node), GFP_NOFS); |
|
if (this_node == NULL) { |
|
befs_error(sb, "befs_btree_read() failed to allocate %zu " |
|
"bytes of memory", sizeof(struct befs_btree_node)); |
|
goto error; |
|
} |
|
|
|
node_off = bt_super.root_node_ptr; |
|
this_node->bh = NULL; |
|
|
|
/* seeks down to first leafnode, reads it into this_node */ |
|
res = befs_btree_seekleaf(sb, ds, &bt_super, this_node, &node_off); |
|
if (res == BEFS_BT_EMPTY) { |
|
brelse(this_node->bh); |
|
kfree(this_node); |
|
*value = 0; |
|
*keysize = 0; |
|
befs_debug(sb, "<--- %s Tree is EMPTY", __func__); |
|
return BEFS_BT_EMPTY; |
|
} else if (res == BEFS_ERR) { |
|
goto error_alloc; |
|
} |
|
|
|
/* find the leaf node containing the key_no key */ |
|
|
|
while (key_sum + this_node->head.all_key_count <= key_no) { |
|
|
|
/* no more nodes to look in: key_no is too large */ |
|
if (this_node->head.right == BEFS_BT_INVAL) { |
|
*keysize = 0; |
|
*value = 0; |
|
befs_debug(sb, |
|
"<--- %s END of keys at %llu", __func__, |
|
(unsigned long long) |
|
key_sum + this_node->head.all_key_count); |
|
brelse(this_node->bh); |
|
kfree(this_node); |
|
return BEFS_BT_END; |
|
} |
|
|
|
key_sum += this_node->head.all_key_count; |
|
node_off = this_node->head.right; |
|
|
|
if (befs_bt_read_node(sb, ds, this_node, node_off) != BEFS_OK) { |
|
befs_error(sb, "%s failed to read node at %llu", |
|
__func__, (unsigned long long)node_off); |
|
goto error_alloc; |
|
} |
|
} |
|
|
|
/* how many keys into this_node is key_no */ |
|
cur_key = key_no - key_sum; |
|
|
|
/* get pointers to datastructures within the node body */ |
|
valarray = befs_bt_valarray(this_node); |
|
|
|
keystart = befs_bt_get_key(sb, this_node, cur_key, &keylen); |
|
|
|
befs_debug(sb, "Read [%llu,%d]: keysize %d", |
|
(long long unsigned int)node_off, (int)cur_key, |
|
(int)keylen); |
|
|
|
if (bufsize < keylen + 1) { |
|
befs_error(sb, "%s keybuf too small (%zu) " |
|
"for key of size %d", __func__, bufsize, keylen); |
|
brelse(this_node->bh); |
|
goto error_alloc; |
|
} |
|
|
|
strlcpy(keybuf, keystart, keylen + 1); |
|
*value = fs64_to_cpu(sb, valarray[cur_key]); |
|
*keysize = keylen; |
|
|
|
befs_debug(sb, "Read [%llu,%d]: Key \"%.*s\", Value %llu", node_off, |
|
cur_key, keylen, keybuf, *value); |
|
|
|
brelse(this_node->bh); |
|
kfree(this_node); |
|
|
|
befs_debug(sb, "<--- %s", __func__); |
|
|
|
return BEFS_OK; |
|
|
|
error_alloc: |
|
kfree(this_node); |
|
|
|
error: |
|
*keysize = 0; |
|
*value = 0; |
|
befs_debug(sb, "<--- %s ERROR", __func__); |
|
return BEFS_ERR; |
|
} |
|
|
|
/** |
|
* befs_btree_seekleaf - Find the first leafnode in the btree |
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* @sb: Filesystem superblock |
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* @ds: Datastream containing btree |
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* @bt_super: Pointer to the superblock of the btree |
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* @this_node: Buffer to return the leafnode in |
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* @node_off: Pointer to offset of current node within datastream. Modified |
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* by the function. |
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* |
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* Helper function for btree traverse. Moves the current position to the |
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* start of the first leaf node. |
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* |
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* Also checks for an empty tree. If there are no keys, returns BEFS_BT_EMPTY. |
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*/ |
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static int |
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befs_btree_seekleaf(struct super_block *sb, const befs_data_stream *ds, |
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befs_btree_super *bt_super, |
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struct befs_btree_node *this_node, |
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befs_off_t * node_off) |
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{ |
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|
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befs_debug(sb, "---> %s", __func__); |
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|
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if (befs_bt_read_node(sb, ds, this_node, *node_off) != BEFS_OK) { |
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befs_error(sb, "%s failed to read " |
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"node at %llu", __func__, *node_off); |
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goto error; |
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} |
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befs_debug(sb, "Seekleaf to root node %llu", *node_off); |
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|
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if (this_node->head.all_key_count == 0 && befs_leafnode(this_node)) { |
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befs_debug(sb, "<--- %s Tree is EMPTY", __func__); |
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return BEFS_BT_EMPTY; |
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} |
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|
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while (!befs_leafnode(this_node)) { |
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|
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if (this_node->head.all_key_count == 0) { |
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befs_debug(sb, "%s encountered " |
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"an empty interior node: %llu. Using Overflow " |
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"node: %llu", __func__, *node_off, |
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this_node->head.overflow); |
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*node_off = this_node->head.overflow; |
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} else { |
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fs64 *valarray = befs_bt_valarray(this_node); |
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*node_off = fs64_to_cpu(sb, valarray[0]); |
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} |
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if (befs_bt_read_node(sb, ds, this_node, *node_off) != BEFS_OK) { |
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befs_error(sb, "%s failed to read " |
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"node at %llu", __func__, *node_off); |
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goto error; |
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} |
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|
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befs_debug(sb, "Seekleaf to child node %llu", *node_off); |
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} |
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befs_debug(sb, "Node %llu is a leaf node", *node_off); |
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|
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return BEFS_OK; |
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|
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error: |
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befs_debug(sb, "<--- %s ERROR", __func__); |
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return BEFS_ERR; |
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} |
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|
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/** |
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* befs_leafnode - Determine if the btree node is a leaf node or an |
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* interior node |
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* @node: Pointer to node structure to test |
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* |
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* Return 1 if leaf, 0 if interior |
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*/ |
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static int |
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befs_leafnode(struct befs_btree_node *node) |
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{ |
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/* all interior nodes (and only interior nodes) have an overflow node */ |
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if (node->head.overflow == BEFS_BT_INVAL) |
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return 1; |
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else |
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return 0; |
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} |
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|
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/** |
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* befs_bt_keylen_index - Finds start of keylen index in a node |
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* @node: Pointer to the node structure to find the keylen index within |
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* |
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* Returns a pointer to the start of the key length index array |
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* of the B+tree node *@node |
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* |
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* "The length of all the keys in the node is added to the size of the |
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* header and then rounded up to a multiple of four to get the beginning |
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* of the key length index" (p.88, practical filesystem design). |
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* |
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* Except that rounding up to 8 works, and rounding up to 4 doesn't. |
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*/ |
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static fs16 * |
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befs_bt_keylen_index(struct befs_btree_node *node) |
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{ |
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const int keylen_align = 8; |
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unsigned long int off = |
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(sizeof (befs_btree_nodehead) + node->head.all_key_length); |
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ulong tmp = off % keylen_align; |
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|
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if (tmp) |
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off += keylen_align - tmp; |
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|
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return (fs16 *) ((void *) node->od_node + off); |
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} |
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|
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/** |
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* befs_bt_valarray - Finds the start of value array in a node |
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* @node: Pointer to the node structure to find the value array within |
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* |
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* Returns a pointer to the start of the value array |
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* of the node pointed to by the node header |
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*/ |
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static fs64 * |
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befs_bt_valarray(struct befs_btree_node *node) |
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{ |
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void *keylen_index_start = (void *) befs_bt_keylen_index(node); |
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size_t keylen_index_size = node->head.all_key_count * sizeof (fs16); |
|
|
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return (fs64 *) (keylen_index_start + keylen_index_size); |
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} |
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|
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/** |
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* befs_bt_keydata - Finds start of keydata array in a node |
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* @node: Pointer to the node structure to find the keydata array within |
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* |
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* Returns a pointer to the start of the keydata array |
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* of the node pointed to by the node header |
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*/ |
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static char * |
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befs_bt_keydata(struct befs_btree_node *node) |
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{ |
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return (char *) ((void *) node->od_node + sizeof (befs_btree_nodehead)); |
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} |
|
|
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/** |
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* befs_bt_get_key - returns a pointer to the start of a key |
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* @sb: filesystem superblock |
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* @node: node in which to look for the key |
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* @index: the index of the key to get |
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* @keylen: modified to be the length of the key at @index |
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* |
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* Returns a valid pointer into @node on success. |
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* Returns NULL on failure (bad input) and sets *@keylen = 0 |
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*/ |
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static char * |
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befs_bt_get_key(struct super_block *sb, struct befs_btree_node *node, |
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int index, u16 * keylen) |
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{ |
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int prev_key_end; |
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char *keystart; |
|
fs16 *keylen_index; |
|
|
|
if (index < 0 || index > node->head.all_key_count) { |
|
*keylen = 0; |
|
return NULL; |
|
} |
|
|
|
keystart = befs_bt_keydata(node); |
|
keylen_index = befs_bt_keylen_index(node); |
|
|
|
if (index == 0) |
|
prev_key_end = 0; |
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else |
|
prev_key_end = fs16_to_cpu(sb, keylen_index[index - 1]); |
|
|
|
*keylen = fs16_to_cpu(sb, keylen_index[index]) - prev_key_end; |
|
|
|
return keystart + prev_key_end; |
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} |
|
|
|
/** |
|
* befs_compare_strings - compare two strings |
|
* @key1: pointer to the first key to be compared |
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* @keylen1: length in bytes of key1 |
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* @key2: pointer to the second key to be compared |
|
* @keylen2: length in bytes of key2 |
|
* |
|
* Returns 0 if @key1 and @key2 are equal. |
|
* Returns >0 if @key1 is greater. |
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* Returns <0 if @key2 is greater. |
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*/ |
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static int |
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befs_compare_strings(const void *key1, int keylen1, |
|
const void *key2, int keylen2) |
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{ |
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int len = min_t(int, keylen1, keylen2); |
|
int result = strncmp(key1, key2, len); |
|
if (result == 0) |
|
result = keylen1 - keylen2; |
|
return result; |
|
} |
|
|
|
/* These will be used for non-string keyed btrees */ |
|
#if 0 |
|
static int |
|
btree_compare_int32(cont void *key1, int keylen1, const void *key2, int keylen2) |
|
{ |
|
return *(int32_t *) key1 - *(int32_t *) key2; |
|
} |
|
|
|
static int |
|
btree_compare_uint32(cont void *key1, int keylen1, |
|
const void *key2, int keylen2) |
|
{ |
|
if (*(u_int32_t *) key1 == *(u_int32_t *) key2) |
|
return 0; |
|
else if (*(u_int32_t *) key1 > *(u_int32_t *) key2) |
|
return 1; |
|
|
|
return -1; |
|
} |
|
static int |
|
btree_compare_int64(cont void *key1, int keylen1, const void *key2, int keylen2) |
|
{ |
|
if (*(int64_t *) key1 == *(int64_t *) key2) |
|
return 0; |
|
else if (*(int64_t *) key1 > *(int64_t *) key2) |
|
return 1; |
|
|
|
return -1; |
|
} |
|
|
|
static int |
|
btree_compare_uint64(cont void *key1, int keylen1, |
|
const void *key2, int keylen2) |
|
{ |
|
if (*(u_int64_t *) key1 == *(u_int64_t *) key2) |
|
return 0; |
|
else if (*(u_int64_t *) key1 > *(u_int64_t *) key2) |
|
return 1; |
|
|
|
return -1; |
|
} |
|
|
|
static int |
|
btree_compare_float(cont void *key1, int keylen1, const void *key2, int keylen2) |
|
{ |
|
float result = *(float *) key1 - *(float *) key2; |
|
if (result == 0.0f) |
|
return 0; |
|
|
|
return (result < 0.0f) ? -1 : 1; |
|
} |
|
|
|
static int |
|
btree_compare_double(cont void *key1, int keylen1, |
|
const void *key2, int keylen2) |
|
{ |
|
double result = *(double *) key1 - *(double *) key2; |
|
if (result == 0.0) |
|
return 0; |
|
|
|
return (result < 0.0) ? -1 : 1; |
|
} |
|
#endif //0
|
|
|