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Message-ID: <20150623230227.GB10037@birch.djwong.org>
Date: Tue, 23 Jun 2015 16:02:27 -0700
From: "Darrick J. Wong" <darrick.wong@...cle.com>
To: mingming cao <mingming.cao@...cle.com>
Cc: linux-ext4@...r.kernel.org
Subject: Re: [RFC 2/2] ext4 btree basic implementation
On Mon, Jun 22, 2015 at 08:24:38PM -0700, mingming cao wrote:
> ---
> ext4_btree.c | 1356 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 1356 insertions(+)
> create mode 100644 ext4_btree.c
>
> diff --git a/ext4_btree.c b/ext4_btree.c
> new file mode 100644
> index 0000000..baf253c
> --- /dev/null
> +++ b/ext4_btree.c
> @@ -0,0 +1,1356 @@
> +/*
> + * copyright (C) 2015 Oracle. All rights reserved.
(Nit-picking, but this should be a capital-C "Copyright")
> + *
> + * This program is free software; you can redistribute it and/or
> + * modify it under the terms of the GNU General Public
> + * License v2 as published by the Free Software Foundation.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
> + * General Public License for more details.
> + *
> + * You should have received a copy of the GNU General Public
> + * License along with this program; if not, write to the
> + * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
> + * Boston, MA 021110-1307, USA.
> + */
> +
> +
> +
> +
> +#include "ext4_btree.h"
> +
> +/*
> + * Calculate offset of the n-th key in a btree node.
> + */
> +static inline unsigned int
> +ext4_btree_key_offset(struct ext4_btree_geo *geo, unsigned int n)
> +{
> + return geo->header_len + n * geo->key_len;
Parentheses around the multiplicative terms would make this a little easier
to scan a line for which variables go together, i.e.
return geo->header_len + (n * geo->key_len);
(Still, a minor nit.)
> +}
> +
> +/*
> + * Calculate offset of the n-th node pointer in a btree node.
> + */
> +static inline unsigned int
> +ext4_btree_val_offset(struct ext4_btree_geo *geo, unsigned int n)
> +{
> + return geo->header_len +
> + geo->max_pairs * geo->key_len +
> + n * geo->val_len;
> +}
> +
> +/*
> + * Calculate offset of the n-th record in a btree leaf node.
> + */
> +static inline unsigned int
> +ext4_btree_rec_offset(struct ext4_btree_geo *geo, unsigned int n)
> +{
> + return geo->header_len + n * geo->rec_len;
> +}
> +
> +/*
> + * Node header access functions
> + */
> +static inline struct ext4_btree_header*
> +ext4_btree_header_addr(struct ext4_btree_node *block)
> +{
> + return (struct ext4_btree_header *)block;
> +}
> +
> +static inline unsigned int
> +ext4_btree_get_numkeys(struct ext4_btree_node *node)
> +{
> + return ext4_btree_header_addr(node)->btree_numkeys;
> +}
> +
> +static inline void
> +ext4_btree_update_numkeys(struct ext4_btree_node *node, unsigned int n)
> +{
> + ext4_btree_header_addr(node)->btree_numkeys = n;
> +}
> +
> +static inline unsigned int
> +ext4_btree_get_numrecs(struct ext4_btree_node *node)
> +{
> + return ext4_btree_header_addr(node)->btree_numkeys;
> +}
> +
> +static inline void
> +ext4_btree_update_numrecs(struct ext4_btree_node *node, unsigned int n)
> +{
> + ext4_btree_header_addr(node)->btree_numkeys = n;
> +}
> +
> +static inline unsigned int
> +ext4_btree_get_level(struct ext4_btree_node *node)
> +{
> + return ext4_btree_header_addr(node)->btree_level;
> +}
> +
> +static inline void
> +ext4_btree_update_level(struct ext4_btree_node *node, unsigned int level)
> +{
> + ext4_btree_header_addr(node)->btree_level = level;
> +}
> +
> +static inline unsigned long long
> +ext4_btree_get_blockno(struct ext4_btree_node *node)
> +{
> + return ext4_btree_header_addr(node)->btree_blockno;
> +}
> +
> +static inline void
> +ext4_btree_update_blockno(struct ext4_btree_node *node,
> + unsigned long long blockno)
> +{
> + ext4_btree_header_addr(node)->btree_blockno = blockno;
> +}
> +
> +/*
> +* Get n-th key address from btree node
> +*/
> +static struct ext4_btree_key*
> +ext4_btree_key_addr(struct ext4_btree_geo *geo,
> + struct ext4_btree_node * node,
> + unsigned int n)
> +{
> + return (struct ext4_btree_key *)
> + ((unsigned char *)node + ext4_btree_key_offset(geo, n));
> +}
> +
> +/*
> + * Set n-th key from btree node
> + */
> +static void
> +ext4_btree_set_key(struct ext4_btree_geo *geo,
> + struct ext4_btree_node *node,
> + unsigned int n,
> + struct ext4_btree_key *key)
> +{
> + struct ext4_btree_key *keyoffset = ext4_btree_key_addr(geo, node, n);
> + *keyoffset = *key;
> +}
> +
> +static void
> +ext4_btree_clear_key(struct ext4_btree_key *key)
> +{
> + key->blockno = 0;
> +}
> +
> +/*
> + * Get n-th val address from btree node
> + */
> +static struct ext4_btree_val*
> +ext4_btree_val_addr(struct ext4_btree_geo *geo,
> + struct ext4_btree_node *node,
> + unsigned int n)
> +{
> + return (struct ext4_btree_val *)
> + ((unsigned char *)node + ext4_btree_val_offset(geo, n));
> +}
> +
> +/*
> + * Set n-th val from btree node
> + */
> +static void
> +ext4_btree_set_val(struct ext4_btree_geo *geo,
> + struct ext4_btree_node *node,
> + unsigned int n,
> + struct ext4_btree_val *val)
> +{
> + struct ext4_btree_val *valaddr = ext4_btree_val_addr(geo, node, n);
> + *valaddr = *val;
> +}
> +
> +static void
> +ext4_btree_clear_val(struct ext4_btree_val *val)
> +{
> + val->blockno = 0;
> +}
> +
> +/*
> + * Get n-th record address from btree node
> + */
> +static struct ext4_btree_rec*
> +ext4_btree_rec_addr(struct ext4_btree_geo *geo,
> + struct ext4_btree_node *node,
> + unsigned int n)
> +{
> + return (struct ext4_btree_rec *)
> + ((unsigned char *)node + ext4_btree_rec_offset(geo, n));
> +}
> +
> +
> +/*
> + * Set n-th value from btree node
> + */
> +static void
> +ext4_btree_set_rec(struct ext4_btree_geo *geo,
> + struct ext4_btree_node *node,
> + unsigned int n,
> + struct ext4_btree_rec *rec)
> +{
> + struct ext4_btree_rec *rec_offset = ext4_btree_rec_addr(geo, node, n);
> + *rec_offset = *rec;
> +}
> +
> +static void
> +ext4_btree_clear_rec(struct ext4_btree_rec *rec)
> +{
> + rec->key.blockno = 0;
> + rec->len = 0;
> + rec->ref_count = 0;
> +}
> +
> +/*
> + * Initialize btree root node
> + */
> +
> +void
> +ext4_btree_root_init(struct ext4_btree_root *root,
> + struct ext4_btree_geo *geo)
> +{
> + root->node = NULL;
> + root->geo = (*geo);
> +}
> +
> +/*
> + * Initialize ref btree root node
> + */
> +void
> +ext4_ref_btree_init(struct ext4_btree_root *root)
> +{
> + ext4_btree_root_init(root, &ref_btree_geo);
> +}
> +
> +/*
> + * Allocate a btree node
> + */
> +struct ext4_btree_node *
> +ext4_btree_node_alloc()
> +{
> + return fs_alloc_btree_node();
I'm assuming this is defined somewhere in your test harness?
> +}
> +
> +/*
> + * Free a btree node
> + */
> +
> +void
> +ext4_btree_node_free( struct ext4_btree_node *node)
> +{
> + fs_free_btree_node(node);
> +}
> +
> +/*
> + * Compare two btree keys.
> + * Return 1 if key1 > key2.
> + * Return 0 if key1 == key2.
> + * Return -1 if key1 < key2.
> + */
> +int
> +ext4_btree_key_comp(struct ext4_btree_geo *geo,
> + struct ext4_btree_key *key1,
> + struct ext4_btree_key *key2)
> +{
> + if (key1->blockno < key2->blockno)
> + return -1;
> + else if (key1->blockno > key2->blockno)
> + return 1;
> + else
> + return 0;
> +}
> +
> +/*
> + * If specified key within record' range
> + * Return -1 if key < record's key
> + * Return 0 if record has the key
> + * Return 1 if record's key + len < key
> + */
> +int
> +ext4_btree_rec_comp(struct ext4_btree_geo *geo,
> + struct ext4_btree_key *key,
> + struct ext4_btree_rec *rec)
> +{
> + if (key->blockno < rec->key.blockno)
> + return -1;
> + else if ((rec->key.blockno + rec->len) <= key->blockno)
> + return 1;
> + else
> + return 0;
> +}
> +
> +/*
> + * Check if the given record has this key
> + * Return 1 if record has this key within range
> + * Return 0 if not
> + */
> +static inline int
> +ext4_btree_rec_has_key(struct ext4_btree_geo *geo,
> + struct ext4_btree_rec *rec,
> + struct ext4_btree_key *key)
> +{
> + return ((rec->key.blockno <= key->blockno) &&
> + ((rec->key.blockno + rec->len) > key->blockno));
> +}
> +
> +static inline void
> +ext4_btree_set_search_path(struct ext4_btree_search_path * spath,
> + int level,
> + struct ext4_btree_node * node,
> + int pos)
> +{
> + if (spath) {
> + spath->node[level] = node;
> + spath->pos[level] = pos;
> + }
> +}
> +
> +/* define the btree layout for refcount btree */
> +struct ext4_btree_geo ref_btree_geo = {
> + EXT4_BTREE_NODESIZE,
> + EXT4_BTREE_HEADER_SIZE,
> + EXT4_BTREE_KEY_SIZE,
> + EXT4_BTREE_VAL_SIZE,
> + EXT4_BTREE_REC_SIZE,
> + EXT4_BTREE_MAX_KEY_VAL_PAIRS,
> + EXT4_BTREE_MAX_RECS
> +};
> +
> +/* remember the index btree node on the search path */
> +struct ext4_btree_search_path {
> + struct ext4_btree_node * node[EXT4_BTREE_MAX_LEVELS];
> + int pos [EXT4_BTREE_MAX_LEVELS];
> +};
> +
> +
> +/*
> + * Initialize the search path
> + */
> +void
> +ext4_btree_init_search_path (struct ext4_btree_search_path *spath)
> +{
> + int i;
> + for (i=0; i< EXT4_BTREE_MAX_LEVELS; i++) {
> + spath->node[i] = NULL;
> + spath->pos[i] = EXT4_BTREE_MAX_KEY_VAL_PAIRS;
> + }
> +}
> +
> +
> +/*
> + * Debug function to print out the whole tree
> + */
> +
> +void
> +ext4_btree_rec_node_print(struct ext4_btree_geo *geo,
> + struct ext4_btree_node *node)
> +{
> + int i;
> + struct ext4_btree_rec *rec;
> + int num_recs;
> +
> + if (node == NULL)
> + return;
> + num_recs = ext4_btree_get_numrecs(node);
> + ext4_btree_trace("==rec== node in block %lld - level %d numrecs %d\n",
> + ext4_btree_get_blockno(node),
> + ext4_btree_get_level(node),
> + ext4_btree_get_numrecs(node));
> + for (i = 0; i < num_recs; i++) {
> + rec = ext4_btree_rec_addr(geo, node, i);
> + ext4_btree_trace("rec%d key 0x%llx len 0x%x refcount %d\n",
> + i, rec->key.blockno, rec->len, rec->ref_count);
> + }
> +}
> +
> +void
> +ext4_btree_index_node_print(struct ext4_btree_geo *geo,
> + struct ext4_btree_node *node)
> +{
> + int i;
> + int num_keys;
> + struct ext4_btree_key *key;
> + struct ext4_btree_val *val;
> +
> + num_keys = ext4_btree_get_numkeys(node);
> + ext4_btree_trace("--key-- node in block %lld - level %d numkeys %d\n",
> + ext4_btree_get_blockno(node),
> + ext4_btree_get_level(node),
> + ext4_btree_get_numkeys(node));
> + for (i = 0; i < num_keys; i++) {
> + key = ext4_btree_key_addr(geo, node, i);
> + val = ext4_btree_val_addr(geo, node, i);
> + ext4_btree_trace("pair%d key 0x%llx val 0x%llx\n",
> + i, key->blockno, val->blockno);
> + }
> +}
> +
> +void
> +ext4_btree_print(struct ext4_btree_root *root)
> +{
> + struct ext4_btree_search_path spath;
> + struct ext4_btree_node * node;
> + struct ext4_btree_val * val;
> + int level;
> + int rootlevel;
> + int pos;
> + int numkeys;
> +
> + if (root == NULL || root->node == NULL) {
> + ext4_btree_trace("Empty tree\n");
> + return;
> + }
> +
> + ext4_btree_trace("Btree Details:\n\n");
> + ext4_btree_init_search_path(&spath);
> + node = root->node;
> + level = rootlevel = ext4_btree_get_level(node);
> + pos = 0;
> + while (level >= 0) {
> + spath.node[level] = node;
> + spath.pos[level] = pos;
> + if (level > 0) {
> + if (pos == 0)
> + ext4_btree_index_node_print(&root->geo, node);
> + numkeys = ext4_btree_get_numkeys(node);
> + if (pos == numkeys) {
> + if (level == rootlevel)
> + break; /* reach the end
> + /* go to parent node */
> + level ++;
> + node = spath.node[level];
> + pos = spath.pos[level] + 1;
> + }
> + else {
> + /* go to next child node */
> + level --;
> + val = ext4_btree_val_addr(&root->geo,
> + node, pos);
> + node = fs_get_btree_node(val->blockno);
> + pos = 0 ;
> + }
> + }
> + else {
> + ext4_btree_rec_node_print(&root->geo, node);
> + if (level == rootlevel)
> + break; /* reach the end
> + /* go to parent node; */
> + level ++;
> + node = spath.node[level];
> + pos = spath.pos[level] + 1;
> + }
> + }
> + ext4_btree_trace("\n");
> +}
> +
> +
> +/*
> + * Lookup for a record contain the specified key in btree
> + * Return NULL if the key is not found
> + */
> +struct ext4_btree_rec*
> +ext4_btree_search_key(struct ext4_btree_root *root,
> + struct ext4_btree_key *key,
> + struct ext4_btree_search_path * spath)
> +{
> + unsigned int i;
> + int level;
> + struct ext4_btree_node *node;
> + struct ext4_btree_key *tmp_key;
> + struct ext4_btree_val *tmp_val;
> + struct ext4_btree_geo *geo;
> + struct ext4_btree_rec *rec = NULL;
> +
> + if (root == NULL || root->node == NULL)
> + return NULL;
> + /* Search through the key-val index nodes. */
> + node = root->node;
> + geo = &root->geo;
> + level = ext4_btree_get_level(node);
> + while (level > 0) {
> + for (i = 0; i < ext4_btree_get_numkeys(node)-1; i++) {
> + tmp_key = ext4_btree_key_addr(geo, node, i + 1);
> + if (ext4_btree_key_comp(geo, key, tmp_key) < 0)
> + break;
> + }
If the keys and records are stored in sorted order, could you bsearch here
instead of linear scanning? Granted the difference might be inconsequential
for the ~252 records in a 4K node, but for a 64k node that's a linear scan
of ~4092 records.
This goes for all the linear scans I see.
> + ext4_btree_set_search_path(spath, level, node, i);
> + tmp_val = ext4_btree_val_addr(geo, node, i);
> + node = fs_get_btree_node(tmp_val->blockno);
> + /* read failure*/
> + if (node == NULL)
> + return NULL;
I wonder if there ought to be a facility for returning integer error codes
and passing in a **node (as an out param) instead of using NULL to cover
"not found" and "badness happened".
> + level --;
> + }
> + /* Search the leaf node */
> + assert(ext4_btree_get_level(node) == 0);
> + rec = ext4_btree_rec_addr(geo, node, 0);
> + i = 0;
> + while (ext4_btree_rec_comp(geo, key, rec) > 0) {
> + i++;
> + if (i >= ext4_btree_get_numkeys(node)) {
> + ext4_btree_set_search_path(spath, 0, node, i);
> + return NULL;
> + }
> + rec = ext4_btree_rec_addr(geo, node, i);
> + }
> + ext4_btree_set_search_path(spath, 0, node, i);
> + if (ext4_btree_rec_comp(geo, key, rec) == 0)
> + return rec;
> + else
> + return NULL;
> +}
> +
> +/*
> + * Lookup for a record contain the specified key in btree
> + * Return NULL if the key is not found
> + */
> +struct ext4_btree_rec*
> +ext4_btree_lookup(struct ext4_btree_root *root, struct ext4_btree_key *key)
> +{
> + return ext4_btree_search_key(root, key, NULL);
> +}
> +
> +/*
> + * Insert a rec into a leaf node at specifid position
> + */
> +void
> +ext4_btree_node_insert_in_leaf(struct ext4_btree_root *root,
> + struct ext4_btree_node *node,
> + struct ext4_btree_rec *rec,
> + int pos)
> +{
> + int numrecs;
> + int i;
> + struct ext4_btree_rec *tmprec;
> +
> + numrecs= ext4_btree_get_numrecs(node);
> + for (i = numrecs; i > pos;i--) {
> + tmprec = ext4_btree_rec_addr(&root->geo, node, i-1);
> + ext4_btree_set_rec(&root->geo, node, i,tmprec);
> + }
memmove?
> + ext4_btree_set_rec(&root->geo, node, pos, rec);
> + ext4_btree_update_numrecs(node,numrecs+1);
> +}
> +
> +/*
> + * Split a leaf node into two
> + */
> +struct ext4_btree_node *
> +ext4_btree_split_leaf(struct ext4_btree_root *root,
> + struct ext4_btree_node *node)
> +{
> + struct ext4_btree_node *rnode;
> + struct ext4_btree_rec *tmprec;
> + unsigned int i;
> +
> + rnode = ext4_btree_node_alloc();
> + if (!rnode) {
> + /* Cant allocate a new node, ERR*/
> + return NULL;
> + }
> + for (i = EXT4_BTREE_MAX_RECS/2; i < EXT4_BTREE_MAX_RECS;i++) {
> + tmprec = ext4_btree_rec_addr(&root->geo, node, i);
> + ext4_btree_set_rec(&root->geo, rnode,
> + (i-EXT4_BTREE_MAX_RECS/2), tmprec);
> + ext4_btree_clear_rec(tmprec);
memcpy/memset?
> + }
> + ext4_btree_update_numrecs(rnode,EXT4_BTREE_MAX_RECS/2);
> + ext4_btree_update_numrecs(node, EXT4_BTREE_MAX_RECS/2);
> + return rnode;
> +}
> +
> +/*
> + * Split a index node into two
> + */
> +struct ext4_btree_node *
> +ext4_btree_split_index(struct ext4_btree_root *root,
> + struct ext4_btree_node *node)
> +{
> + struct ext4_btree_node *rnode;
> + struct ext4_btree_key *tmp_key;
> + struct ext4_btree_val *tmp_val;
> + unsigned int i;
> +
> + rnode = ext4_btree_node_alloc();
> + if (!rnode) {
> + /* Cant allocate a new node, ERR*/
> + return NULL;
> + }
> + /* split key-val pairs between old node and new node */
> + for (i = EXT4_BTREE_MAX_KEY_VAL_PAIRS/2;
> + i < EXT4_BTREE_MAX_KEY_VAL_PAIRS;
> + i++) {
> + tmp_key = ext4_btree_key_addr(&root->geo, node, i);
> + ext4_btree_set_key(&root->geo, rnode,
> + (i-EXT4_BTREE_MAX_KEY_VAL_PAIRS/2),tmp_key);
> + ext4_btree_clear_key(tmp_key);
> + tmp_val = ext4_btree_val_addr(&root->geo, node, i);
> + ext4_btree_set_val(&root->geo, rnode,
> + (i-EXT4_BTREE_MAX_KEY_VAL_PAIRS/2),tmp_val);
> + ext4_btree_clear_val(tmp_val);
> + }
> + /* set level and numkeys in new node */
> + ext4_btree_update_level(rnode, ext4_btree_get_level(node));
> + ext4_btree_update_numkeys(rnode,EXT4_BTREE_MAX_KEY_VAL_PAIRS/2);
> + /* set numkeys in old node */
> + ext4_btree_update_numkeys(node, EXT4_BTREE_MAX_KEY_VAL_PAIRS/2);
> + return rnode;
> +}
> +
> +
> +/*
> + * Insert a key-val pair into a index node at specified position
> + */
> +void
> +ext4_btree_node_insert_in_index(struct ext4_btree_root *root,
> + struct ext4_btree_node *node,
> + struct ext4_btree_key *key,
> + struct ext4_btree_val *val,
> + int pos)
> +{
> + int i;
> + int numkeys;
> + struct ext4_btree_key *pkey;
> + struct ext4_btree_val *pval;
> +
> + numkeys = ext4_btree_get_numkeys(node);
> + for (i = numkeys - 1; i >= pos; i--) {
> + pkey = ext4_btree_key_addr(&root->geo, node, i);
> + ext4_btree_set_key(&root->geo, node, i + 1, pkey);
> + pval = ext4_btree_val_addr(&root->geo, node, i);
> + ext4_btree_set_val(&root->geo, node, i + 1, pval);
> + }
> + ext4_btree_set_key(&root->geo, node, pos, key);
> + ext4_btree_set_val(&root->geo, node, pos, val);
> + ext4_btree_update_numkeys(node, numkeys + 1);
> +}
> +
> +/*
> + * Grow tree by one more level. Return the new root node.
> + */
> +struct ext4_btree_node *
> +ext4_btree_grow(struct ext4_btree_root *root,
> + struct ext4_btree_node *lnode,
> + struct ext4_btree_node *rnode,
> + int level)
> +{
> + struct ext4_btree_node * newroot;
> + struct ext4_btree_key * key;
> + struct ext4_btree_val val;
> +
> + newroot = ext4_btree_node_alloc();
> + if (!newroot) {
> + /* Cant allocate a new node, ERR*/
> + return NULL;
> + }
> +
> + ext4_btree_update_level(newroot, level);
> +
> + key = ext4_btree_key_addr(&root->geo, lnode, 0);
> + ext4_btree_set_key(&root->geo, newroot, 0, key);
> + val.blockno = ext4_btree_get_blockno(lnode);
> + ext4_btree_set_val(&root->geo, newroot, 0, &val);
> +
> + key = ext4_btree_key_addr(&root->geo, rnode, 0);
> + ext4_btree_set_key(&root->geo, newroot, 1, key);
> + val.blockno = ext4_btree_get_blockno(rnode);
> + ext4_btree_set_val(&root->geo, newroot, 1, &val);
> +
> + ext4_btree_update_numkeys(newroot, 2);
> +
> + return newroot;
> +
> +}
> +
> +/*
> + * Insert a record to the btree
> + */
> +int
> +ext4_btree_insert(struct ext4_btree_root *root, struct ext4_btree_rec *rec)
> +{
> + unsigned int level;
> + struct ext4_btree_node *node, *rnode, *newroot;
> + struct ext4_btree_key *key, *rkey;
> + struct ext4_btree_val rval;
> + struct ext4_btree_search_path spath;
> + int pos, full, numkeys;
> + struct ext4_btree_rec *searchrec;
> +
> + if (root->node == NULL) {
> + /* empty tree */
> + node = ext4_btree_node_alloc();
> + if (node == NULL)
> + return -1;
> + root->node = node;
> + ext4_btree_update_level(root->node, 0);
> + ext4_btree_trace(
> + "==rec 0x%llx will be insert in node in block %lld "\
> + "- level %d pos %d\n",
> + rec->key.blockno,
> + ext4_btree_get_blockno(root->node),
> + ext4_btree_get_level(root->node),
> + 0);
> +
> + ext4_btree_node_insert_in_leaf(root, root->node, rec, 0);
> + return 0;
> + }
> +
> + /*
> + * First we search if the key already present,
> + * In the search process, all levels node pointer and position are stored
> + * in search pointer for later use
> + * there is no duplicated key allowed in the tree
> + */
> + ext4_btree_init_search_path(&spath);
> + key = &rec->key;
> + searchrec = ext4_btree_search_key(root, key, &spath);
> +
> + if (searchrec) {
> + node = spath.node[0];
> + pos = spath.pos[0];
> + ext4_btree_trace("==rec 0x%llx found in node in block %lld " \
> + "- level %d pos %d\n",
> + rec->key.blockno,
> + ext4_btree_get_blockno(node),
> + ext4_btree_get_level(node),
> + pos);
> + return -1;
> + }
> + level = 0;
> + node = spath.node[0];
> + pos = spath.pos[0];
> + full = ext4_btree_get_numkeys(node) == EXT4_BTREE_MAX_RECS;
> + ext4_btree_trace(
> + "==rec 0x%llx will be insert in node in block %lld "\
> + "- level %d pos %d\n",
> + rec->key.blockno,
> + ext4_btree_get_blockno(node),
> + ext4_btree_get_level(node),
> + pos);
> +
> + if (!full) {
> + ext4_btree_node_insert_in_leaf(root, node, rec, pos);
> + while (pos == 0 &&
> + (++level <= ext4_btree_get_level(root->node))) {
> + /* update parent key */
> + node = spath.node[level];
> + pos = spath.pos[level];
> + ext4_btree_set_key(&root->geo, node, pos, key);
> + }
> + return 0;
> + }
> +
> + /* check if B tree root is full and level reach the max */
> + if ((ext4_btree_get_level(root->node) == EXT4_BTREE_MAX_LEVELS - 1) &&
> + (ext4_btree_get_numkeys(root->node)
> + == EXT4_BTREE_MAX_KEY_VAL_PAIRS)) {
> + ext4_btree_trace("Tree reach max level, no more insert\n");
> + return -1; // Tree reach the max level
> + }
> +
> + /* leaf node is full, split it to make space to insert new rec*/
> + numkeys = ext4_btree_get_numkeys(node);
> + rnode = ext4_btree_split_leaf(root, node);
> + if (rnode == NULL)
> + return -1;
> + if (pos > EXT4_BTREE_MAX_RECS/2)
> + ext4_btree_node_insert_in_leaf(root, rnode, rec,
> + pos - EXT4_BTREE_MAX_RECS/2);
> + else
> + ext4_btree_node_insert_in_leaf(root, node, rec, pos);
> +
> + /* split index nodes if full, all the way up to root */
> + while (level < ext4_btree_get_level(root->node)) {
> + /* Pick up the first key*/
> + rkey = ext4_btree_key_addr(&root->geo, rnode, 0);
> + rval.blockno = ext4_btree_get_blockno(rnode);
> + level ++;
> + node = spath.node[level];
> + pos = spath.pos[level];
> + numkeys = ext4_btree_get_numkeys(node);
> + full = (numkeys == EXT4_BTREE_MAX_KEY_VAL_PAIRS);
> + if (!full) {
> + ext4_btree_node_insert_in_index(root, node, rkey,
> + &rval, pos + 1);
> + break;
> + }
> + rnode = ext4_btree_split_index(root, node);
> + if (rnode == NULL)
> + return -1;
> + if (pos > EXT4_BTREE_MAX_KEY_VAL_PAIRS/2 ) {
> + ext4_btree_node_insert_in_index(root, rnode, rkey,
> + &rval, pos - EXT4_BTREE_MAX_KEY_VAL_PAIRS/2 + 1);
> + } else {
> + ext4_btree_node_insert_in_index(root, node, rkey,
> + &rval, pos + 1);
> + }
> + }
> + if (level == ext4_btree_get_level(node) && full) {
> + /* If root is split, grow tree by one more level and assign new root */
> + newroot = ext4_btree_grow(root, node, rnode, level + 1);
> + if (newroot != NULL) {
> + root->node = newroot;
> + }
> + }
> + return 0;
> +}
> +
> +
> +/*
> + * Delete one record from leaf node
> + */
> +void
> +ext4_btree_delete_one(struct ext4_btree_root *root,
> + struct ext4_btree_node *node,
> + int pos)
> +{
> + unsigned int i;
> + struct ext4_btree_rec* tmprec;
> + unsigned int numrecs;
> +
> + numrecs= ext4_btree_get_numrecs(node);
> + for (i = pos; i< numrecs - 1; i++) {
> + tmprec = ext4_btree_rec_addr(&root->geo, node, i + 1);
> + ext4_btree_set_rec(&root->geo, node, i, tmprec);
> + }
> + ext4_btree_update_numrecs(node, numrecs - 1);
> +}
> +
> +/*
> + * Delete one key/val pair from index node
> + */
> +
> +void
> +ext4_btree_delete_one_keyval(struct ext4_btree_root *root,
> + struct ext4_btree_node *node,
> + int pos)
> +{
> + unsigned int i;
> + struct ext4_btree_key* key;
> + struct ext4_btree_val* val;
> + unsigned int numkeys;
> +
> + numkeys= ext4_btree_get_numkeys(node);
> + for (i = pos; i< numkeys - 1; i++) {
> + key = ext4_btree_key_addr(&root->geo, node, i + 1);
> + val = ext4_btree_val_addr(&root->geo, node, i + 1);
> + ext4_btree_set_key(&root->geo, node, i, key);
> + ext4_btree_set_val(&root->geo, node, i, val);
> + }
> + ext4_btree_update_numkeys(node, numkeys - 1);
> +
> +}
> +
> +
> +/*
> + * Borrow one record or key/val pair from left sibling
> + */
> +void
> +ext4_btree_borrow_one_left (struct ext4_btree_root *root,
> + struct ext4_btree_node *parent,
> + struct ext4_btree_node *lnode,
> + struct ext4_btree_node *rnode,
> + int pos,
> + int level)
> +{
> + struct ext4_btree_rec *rec;
> + struct ext4_btree_key *key;
> + struct ext4_btree_val *val;
> + int numrecs;
> + int numkeys;
> +
> + if (level == 0) {
> + numrecs = ext4_btree_get_numrecs(lnode);
> + rec = ext4_btree_rec_addr(&root->geo, lnode, numrecs - 1);
> + key = &rec->key;
> + ext4_btree_node_insert_in_leaf(root, rnode, rec, 0);
> + ext4_btree_delete_one(root, lnode, numrecs - 1);
> + } else {
> + numkeys = ext4_btree_get_numkeys(lnode);
> + key = ext4_btree_key_addr(&root->geo, lnode, numkeys - 1);
> + val = ext4_btree_val_addr(&root->geo, lnode, numkeys - 1);
> + ext4_btree_node_insert_in_index(root, rnode, key, val, 0);
> + ext4_btree_delete_one_keyval(root, lnode, numkeys - 1);
> + }
> + /* update parent node key */
> + ext4_btree_set_key(&root->geo, parent, pos, key);
> +
> +}
> +
> +/*
> + * Borrow one record or key/val pair from right sibling
> + */
> +void
> +ext4_btree_borrow_one_right (struct ext4_btree_root *root,
> + struct ext4_btree_node *parent,
> + struct ext4_btree_node *lnode,
> + struct ext4_btree_node *rnode,
> + int pos,
> + int level)
> +{
> + struct ext4_btree_rec *rec;
> + struct ext4_btree_key *key;
> + struct ext4_btree_val *val;
> + int numrecs;
> + int numkeys;
> +
> + if (level == 0) {
> + rec = ext4_btree_rec_addr(&root->geo, rnode, 0);
> + key = &rec->key;
> + numrecs = ext4_btree_get_numrecs(lnode);
> + ext4_btree_node_insert_in_leaf(root, lnode, rec, numrecs);
> + ext4_btree_delete_one(root, rnode, 0);
> + } else {
> + key = ext4_btree_key_addr(&root->geo, rnode, 0);
> + val = ext4_btree_val_addr(&root->geo, rnode, 0);
> + numkeys = ext4_btree_get_numkeys(lnode);
> + ext4_btree_node_insert_in_index(root, lnode, key, val, numkeys);
> + ext4_btree_delete_one_keyval(root, rnode, 0);
> + }
> + /* update parent node key */
> + ext4_btree_set_key(&root->geo, parent, pos + 1, key);
> +}
> +
> +int
> +ext4_btree_rotate(struct ext4_btree_root *root,
> + struct ext4_btree_search_path *spath,
> + struct ext4_btree_node *node, int level)
> +{
> + struct ext4_btree_val * val;
> + struct ext4_btree_node *parent, *lnode, *rnode;
> + int pos = 0;
> + int numkeys;
> +
> + parent = spath->node[level + 1];
> + pos = spath->pos[level + 1];
> +
> + if (pos > 0) {
> + /* check the left sibling first*/
> + val = ext4_btree_val_addr(&root->geo, parent, pos - 1);
node->node_header.leftsib?
> + lnode = fs_get_btree_node(val->blockno);
> + if (lnode) {
> + numkeys = ext4_btree_get_numkeys(lnode);
> + if (numkeys >= EXT4_BTREE_MIN_RECS + 1) {
> + /* we could shift a record from left sibling to the node*/
> + ext4_btree_borrow_one_left(root, parent, lnode,
> + node, pos, level);
> + return 0;
> + }
> + }
> + }
> +
> + numkeys = ext4_btree_get_numkeys(parent);
> + if (pos < numkeys -1) {
> + val = ext4_btree_val_addr(&root->geo, parent, pos + 1);
> + rnode = fs_get_btree_node(val->blockno);
> + if (rnode) {
> + numkeys = ext4_btree_get_numkeys(rnode);
> + if (numkeys >= EXT4_BTREE_MIN_RECS + 1) {
> + /* we could shift a record from left sibling to the node*/
> + ext4_btree_borrow_one_right(root, parent, node,
> + rnode, pos, level);
> + return 0;
> + }
> + }
> + }
> +
> + return -1;
> +
> +}
> +
> +/*
> + * Merge leaf nodes
> + */
> +
> +int
> +ext4_btree_merge_leaf(struct ext4_btree_root *root,
> + struct ext4_btree_search_path *spath,
> + struct ext4_btree_node *node)
> +{
> + int num, lnum, rnum;
> + struct ext4_btree_node * parent, *lnode, *rnode;
> + int i, pos;
> + struct ext4_btree_rec *rec;
> + struct ext4_btree_val *val;
> +
> + parent = spath->node[1];
> + pos = spath->pos[1];
> +
> + num = ext4_btree_get_numrecs(node);
> +
> + /* try to merge left sibling first */
> + if (pos > 0) {
> + val = ext4_btree_val_addr(&root->geo, parent, pos - 1);
> + lnode = fs_get_btree_node(val->blockno);
> + if (!lnode) {
> + return -1;
> + /* err!*/
> + }
> +
> + lnum = ext4_btree_get_numrecs(lnode);
> +
> + for (i = 0; i < num; i++) {
> + rec = ext4_btree_rec_addr(&root->geo, node, i);
> + ext4_btree_node_insert_in_leaf(root, lnode, rec, lnum+i);
> + }
> + // delete parent key-val pair
> + ext4_btree_delete_one_keyval(root, parent, pos);
> + ext4_btree_node_free(node);
> + return 0;
> + }
> + /* then try to merge with right sibling */
> + val = ext4_btree_val_addr(&root->geo, parent, pos + 1);
> + rnode = fs_get_btree_node(val->blockno);
> + if (!rnode) {
> + return -1;
> + /* err!*/
> + }
> +
> + rnum = ext4_btree_get_numrecs(rnode);
> +
> + for (i = 0; i < rnum; i++) {
> + rec = ext4_btree_rec_addr(&root->geo, rnode, i);
> + ext4_btree_node_insert_in_leaf(root, node, rec, num+i);
> + }
> + // delete parent key-val pair
> + ext4_btree_delete_one_keyval(root, parent, pos + 1);
> + ext4_btree_node_free(rnode);
> + return 0;
> +}
> +
> +
> +/*
> + * Merge index nodes
> + */
> +
> +int
> +ext4_btree_merge_index(struct ext4_btree_root *root,
> + struct ext4_btree_search_path *spath,
> + struct ext4_btree_node *node, int level)
> +
> +{
> + int num, lnum, rnum, pnum;
> + struct ext4_btree_node * parent, *lnode, *rnode;
> + int i, pos;
> + struct ext4_btree_key *key;
> + struct ext4_btree_val *val;
> +
> + parent = spath->node[level + 1];
> + pos = spath->pos[level + 1];
> +
> + num = ext4_btree_get_numkeys(node);
> +
> + /* try to merge left sibling first */
> + if (pos > 0) {
> + val = ext4_btree_val_addr(&root->geo, parent, pos - 1);
> + lnode = fs_get_btree_node(val->blockno);
> + if (!lnode) {
> + /* err!*/
> + return -1;
> + }
> +
> + lnum = ext4_btree_get_numkeys(lnode);
> +
> + for (i = 0; i < num; i++) {
> + key = ext4_btree_key_addr(&root->geo, node, i);
> + val = ext4_btree_val_addr(&root->geo, node, i);
> + ext4_btree_node_insert_in_index(root, lnode, key,
> + val, lnum + i);
> + }
> + // delete parent key-val pair
> + ext4_btree_delete_one_keyval(root, parent, pos);
> + ext4_btree_node_free(node);
> + return 0;
> + }
> + pnum = ext4_btree_get_numkeys(parent);
> + if (pnum > 1) {
> + /* then try to merge with right sibling */
> + val = ext4_btree_val_addr(&root->geo, parent, 1); /* pos is always 0*/
> + rnode = fs_get_btree_node(val->blockno);
> + if (!rnode) {
> + return -1;
> + /* err!*/
> + }
> +
> + rnum = ext4_btree_get_numkeys(rnode);
> +
> + for (i = 0; i < rnum; i++) {
> + key = ext4_btree_key_addr(&root->geo, rnode, i);
> + val = ext4_btree_val_addr(&root->geo, rnode, i);
> + ext4_btree_node_insert_in_index(root, node, key,
> + val, num + i);
> + }
> + // delete parent key-val pair
> + ext4_btree_delete_one_keyval(root, parent, pos + 1);
> + ext4_btree_node_free(rnode);
> + ext4_btree_print(root);
> + } else{
> + /* shrink level */
> + ext4_btree_node_free(root->node);
> + root->node = node;
> + ext4_btree_print(root);
> + }
> +
> + return 0;
> +}
> +
> +
> +/*
> + * Delete a record from the btree
> + */
> +int
> +ext4_btree_delete(struct ext4_btree_root *root, struct ext4_btree_key *key)
> +{
> + struct ext4_btree_node *node, *parent;
> + struct ext4_btree_search_path spath;
> + int pos, p_pos;
> + struct ext4_btree_rec *searchrec;
> + int level;
> + int tree_height = ext4_btree_get_level(root->node);
> + int ret;
> +
> + /*
> + * First we search if the key already present,
> + * In the search process, all levels node pointer and position are stored
> + * in search pointer for later use
> + * there is no duplicated key allowed in the tree
> + */
> + ext4_btree_init_search_path(&spath);
> + searchrec = ext4_btree_search_key(root, key, &spath);
> + if (!searchrec)
> + /* record doesnt exist */
> + return -1;
> + node = spath.node[0];
> + pos = spath.pos[0];
> + ext4_btree_trace("==Delete : rec 0x%llx found in node in block %lld " \
> + "- level %d pos %d\n",
> + key->blockno,
> + ext4_btree_get_blockno(node),
> + ext4_btree_get_level(node),
> + pos);
> + ext4_btree_delete_one(root, node, pos);
> + if (pos == 0) {
> + /* update parent key */
> + parent = spath.node[1];
> + p_pos = spath.pos[1];
> + key = ext4_btree_key_addr(&root->geo, node, 0);
> + ext4_btree_set_key(&root->geo, parent, p_pos, key);
> + }
> + /*
> + * If the node is root node, which we do not require minmum number of records,
> + * then we are good now, exit
> + */
> + if (ext4_btree_get_level(root->node) == 0)
> + return 0;
> + if (ext4_btree_get_numrecs(node) >= EXT4_BTREE_MIN_RECS)
> + return 0;
> +
> + level = 0;
> + while (level < tree_height &&
> + ext4_btree_get_numrecs(node) < EXT4_BTREE_MIN_RECS) {
> + ret = ext4_btree_rotate(root, &spath, node, level);
> + if (!ret)
> + return 0; /* node can be rotated with sibling nodes */
> +
> + if (level == 0)
> + ret = ext4_btree_merge_leaf(root, &spath, node);
> + else
> +
> + ret = ext4_btree_merge_index(root, &spath,
> + node, level);
> + if (ret) {
> + /* err*/
> + return ret;
> + }
> + level ++;
> + node = spath.node[level];
> + }
> + return 0;
> +}
> +
> +
> +/*
> + * Check if a btree is valid
> + */
> +
> +int
> +ext4_btree_index_node_check(struct ext4_btree_root * root,
> + struct ext4_btree_node *node)
> +{
> + int i;
> + int num_keys;
> + struct ext4_btree_key *key, *lkey = NULL;
> + struct ext4_btree_val *val;
> +
> + if (node == NULL)
> + return -1;
> +
> + num_keys = ext4_btree_get_numkeys(node);
> + if (root->node != node) {
> + // non-root node
> + if (num_keys < EXT4_BTREE_MIN_KEY_VAL_PAIRS ||
> + num_keys > EXT4_BTREE_MAX_KEY_VAL_PAIRS) {
I think it's important to check !(num_keys > EXT4_BTREE_MAX_KEY_VAL_PAIRS)
for root nodes?
Also, there's no check of CRC, leftsib, rightsib, or blockno.
> + ext4_btree_trace("Invalid numkeys %d in node %lld - " \
> + "level %d\n",
> + num_keys,
> + ext4_btree_get_blockno(node),
> + ext4_btree_get_level(node));
> + return -2;
> + }
> + }
> +
> + for (i = 0; i < num_keys; i++) {
> + key = ext4_btree_key_addr(&root->geo, node, i);
> + val = ext4_btree_val_addr(&root->geo, node, i);
> + if (lkey != NULL && ext4_btree_key_comp(&root->geo, lkey, key) >= 0) {
> + ext4_btree_trace("Keys are not sorted in node %lld" \
> + "- level %d lkey %d 0x%llx key %d 0x%llx\n",
> + ext4_btree_get_blockno(node),
> + ext4_btree_get_level(node),
> + i-1, key->blockno, i, key->blockno);
> + return -3;
> + }
> + lkey = key;
> + }
> + return 0;
> +}
> +
> +
> +int
> +ext4_btree_rec_node_check(struct ext4_btree_root * root,
> + struct ext4_btree_node *node)
> +{
> + int i;
> + struct ext4_btree_rec *rec, *lrec = NULL;
> + int num_recs;
> +
> + if (node == NULL)
> + return -1;
> +
> + num_recs = ext4_btree_get_numrecs(node);
> + if (root->node != node) {
> + // non-root node
> + if (num_recs < EXT4_BTREE_MIN_RECS ||
> + num_recs > EXT4_BTREE_MAX_RECS) {
I think it's still necessary to check !(num_recs > EXT4_BTREE_MAX_RECS) for
root nodes.
Also, there's no check of CRC, leftsib, rightsib, or blockno.
> + ext4_btree_trace("Invalid numrecs %d in node %lld - " \
> + "level %d\n",
> + num_recs,
> + ext4_btree_get_blockno(node),
> + ext4_btree_get_level(node));
> + return -2;
Wading in a bit here, but ... return -EUCLEAN?
More generally, are these int returns supposed to be regular error codes?
> + }
> + }
> + for (i = 0; i < num_recs; i++) {
> + rec = ext4_btree_rec_addr(&root->geo, node, i);
> + if (lrec != NULL &&
> + ext4_btree_key_comp(&root->geo, &lrec->key, &rec->key) >= 0) {
> + ext4_btree_trace("Rec are not sorted in block 0x%llx" \
> + "lkey %d 0x%llx key %d 0x%llx \n",
> + ext4_btree_get_blockno(node),
> + i - 1, lrec->key.blockno, i, rec->key.blockno);
> + return -3;
> + }
> + }
> + return 0;
> +}
> +
> +int
> +ext4_btree_valid_check(struct ext4_btree_root *root)
> +{
> + struct ext4_btree_search_path spath;
96 bytes on the stack, hm. I guess it's not likely to nest too many levels
deep.
> + struct ext4_btree_header * header;
> + struct ext4_btree_node * node;
> + struct ext4_btree_val * val;
> + int level;
> + int rootlevel;
> + int pos;
> + int numkeys;
> + int result;
> +
> + if (root == NULL || root->node == NULL) {
> + return 0;
> + }
> + /* check geo */
> + if (root->geo.header_len == 0 ||
> + root->geo.node_len == 0 ||
> + root->geo.key_len == 0 ||
> + root->geo.val_len == 0 ||
> + root->geo.rec_len == 0 ||
> + root->geo.max_pairs == 0 ||
> + root->geo.max_records == 0)
> + {
> + ext4_btree_trace("tree geo is invalid %d %d %d %d %d %d %d\n",
> + root->geo.header_len,
> + root->geo.node_len,
> + root->geo.key_len,
> + root->geo.val_len,
> + root->geo.rec_len,
> + root->geo.max_pairs,
> + root->geo.max_records);
> + return -1;
> + }
> + if (root->geo.max_pairs % 2 == 1 || root->geo.max_records % 2 == 1) {
> + ext4_btree_trace("tree geo does not support odd pairs %d %d\n",
Oh? I'm a little surprised by this requirement, since the header didn't say
anything about it.
(Also, seeing as those two values are known at compile time, this could be
a compiletime_assert()?)
> + root->geo.max_pairs,
> + root->geo.max_records);
> + return -1;
> + }
> +
> + /* check tree */
> + ext4_btree_init_search_path(&spath);
> + node = root->node;
> + level = rootlevel = ext4_btree_get_level(node);
> + pos = 0;
Should we check level < 8 here?
> + while (level >= 0) {
> + spath.node[level] = node;
> + spath.pos[level] = pos;
> + header = ext4_btree_header_addr(node);
> + if (header->btree_magic != REF_BTREE_MAGIC) {
> + ext4_btree_trace("node 0x%p block %lld has no MAGIC stamp. level %d pos %d\n",
> + node, ext4_btree_get_blockno(node), level, pos);
> + return -1;
> + }
I think there needs to be a check for header->level and header->numkeys here.
(Ok, enough for now.)
--D
> + if (level > 0) {
> + if (pos == 0) {
> + result = ext4_btree_index_node_check(root,
> + node);
> + if (result != 0)
> + return result;
> + }
> + numkeys = ext4_btree_get_numkeys(node);
> + if (pos == numkeys) {
> + if (level == rootlevel)
> + break; /* reach the end
> + /* go to parent node */
> + level ++;
> + node = spath.node[level];
> + pos = spath.pos[level] + 1;
> + }
> + else {
> + /* go to next child node */
> + level --;
> + val = ext4_btree_val_addr(&root->geo,
> + node, pos);
> + node = fs_get_btree_node(val->blockno);
> + pos = 0;
> + }
> + }
> + else {
> + result = ext4_btree_rec_node_check(root, node);
> + if (result != 0)
> + return result;
> + if (level == rootlevel)
> + break; // reach the end
> + /* go to parent node; */
> + level ++;
> + node = spath.node[level];
> + pos = spath.pos[level] + 1;
> + }
> + }
> + return 0;
> +}
> --
> 1.9.1
>
> --
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