Btrfs: Commenting/cleanup
Signed-off-by: Chris Mason <chris.mason@oracle.com>
This commit is contained in:
Chris Mason
David Woodhouse
Родитель
eb60ceac0e
Коммит
74123bd72a
249
fs/btrfs/ctree.c
249
fs/btrfs/ctree.c
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@ -20,6 +20,11 @@ static void release_path(struct ctree_root *root, struct ctree_path *p)
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}
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}
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/*
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* The leaf data grows from end-to-front in the node.
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* this returns the address of the start of the last item,
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* which is the stop of the leaf data stack
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*/
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static inline unsigned int leaf_data_end(struct leaf *leaf)
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{
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unsigned int nr = leaf->header.nritems;
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@ -28,6 +33,11 @@ static inline unsigned int leaf_data_end(struct leaf *leaf)
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return leaf->items[nr-1].offset;
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}
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/*
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* The space between the end of the leaf items and
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* the start of the leaf data. IOW, how much room
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* the leaf has left for both items and data
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*/
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static inline int leaf_free_space(struct leaf *leaf)
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{
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int data_end = leaf_data_end(leaf);
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@ -36,6 +46,9 @@ static inline int leaf_free_space(struct leaf *leaf)
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return (char *)(leaf->data + data_end) - (char *)items_end;
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}
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/*
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* compare two keys in a memcmp fashion
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*/
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int comp_keys(struct key *k1, struct key *k2)
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{
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if (k1->objectid > k2->objectid)
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@ -52,6 +65,16 @@ int comp_keys(struct key *k1, struct key *k2)
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return -1;
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return 0;
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}
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/*
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* search for key in the array p. items p are item_size apart
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* and there are 'max' items in p
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* the slot in the array is returned via slot, and it points to
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* the place where you would insert key if it is not found in
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* the array.
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*
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* slot may point to max if the key is bigger than all of the keys
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*/
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int generic_bin_search(char *p, int item_size, struct key *key,
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int max, int *slot)
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{
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@ -92,6 +115,14 @@ int bin_search(struct node *c, struct key *key, int *slot)
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return -1;
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}
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/*
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* look for key in the tree. path is filled in with nodes along the way
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* if key is found, we return zero and you can find the item in the leaf
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* level of the path (level 0)
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*
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* If the key isn't found, the path points to the slot where it should
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* be inserted.
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*/
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int search_slot(struct ctree_root *root, struct key *key, struct ctree_path *p)
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{
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struct tree_buffer *b = root->node;
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@ -120,12 +151,18 @@ int search_slot(struct ctree_root *root, struct key *key, struct ctree_path *p)
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return -1;
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}
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/*
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* adjust the pointers going up the tree, starting at level
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* making sure the right key of each node is points to 'key'.
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* This is used after shifting pointers to the left, so it stops
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* fixing up pointers when a given leaf/node is not in slot 0 of the
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* higher levels
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*/
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static void fixup_low_keys(struct ctree_root *root,
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struct ctree_path *path, struct key *key,
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int level)
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{
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int i;
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/* adjust the pointers going up the tree */
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for (i = level; i < MAX_LEVEL; i++) {
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struct node *t;
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int tslot = path->slots[i];
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@ -139,64 +176,16 @@ static void fixup_low_keys(struct ctree_root *root,
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}
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}
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int __insert_ptr(struct ctree_root *root,
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struct ctree_path *path, struct key *key,
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u64 blocknr, int slot, int level)
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{
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struct node *c;
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struct node *lower;
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struct key *lower_key;
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int nritems;
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/* need a new root */
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if (!path->nodes[level]) {
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struct tree_buffer *t;
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t = alloc_free_block(root);
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c = &t->node;
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memset(c, 0, sizeof(c));
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c->header.nritems = 2;
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c->header.flags = node_level(level);
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c->header.blocknr = t->blocknr;
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lower = &path->nodes[level-1]->node;
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if (is_leaf(lower->header.flags))
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lower_key = &((struct leaf *)lower)->items[0].key;
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else
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lower_key = lower->keys;
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memcpy(c->keys, lower_key, sizeof(struct key));
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memcpy(c->keys + 1, key, sizeof(struct key));
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c->blockptrs[0] = path->nodes[level-1]->blocknr;
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c->blockptrs[1] = blocknr;
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/* the path has an extra ref to root->node */
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tree_block_release(root, root->node);
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root->node = t;
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t->count++;
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write_tree_block(root, t);
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path->nodes[level] = t;
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path->slots[level] = 0;
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if (c->keys[1].objectid == 0)
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BUG();
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return 0;
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}
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lower = &path->nodes[level]->node;
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nritems = lower->header.nritems;
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if (slot > nritems)
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BUG();
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if (nritems == NODEPTRS_PER_BLOCK)
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BUG();
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if (slot != nritems) {
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memmove(lower->keys + slot + 1, lower->keys + slot,
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(nritems - slot) * sizeof(struct key));
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memmove(lower->blockptrs + slot + 1, lower->blockptrs + slot,
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(nritems - slot) * sizeof(u64));
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}
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memcpy(lower->keys + slot, key, sizeof(struct key));
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lower->blockptrs[slot] = blocknr;
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lower->header.nritems++;
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if (lower->keys[1].objectid == 0)
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BUG();
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write_tree_block(root, path->nodes[level]);
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return 0;
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}
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/*
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* try to push data from one node into the next node left in the
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* tree. The src node is found at specified level in the path.
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* If some bytes were pushed, return 0, otherwise return 1.
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*
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* Lower nodes/leaves in the path are not touched, higher nodes may
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* be modified to reflect the push.
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*
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* The path is altered to reflect the push.
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*/
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int push_node_left(struct ctree_root *root, struct ctree_path *path, int level)
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{
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int slot;
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@ -259,6 +248,16 @@ int push_node_left(struct ctree_root *root, struct ctree_path *path, int level)
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return 0;
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}
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/*
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* try to push data from one node into the next node right in the
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* tree. The src node is found at specified level in the path.
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* If some bytes were pushed, return 0, otherwise return 1.
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*
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* Lower nodes/leaves in the path are not touched, higher nodes may
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* be modified to reflect the push.
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*
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* The path is altered to reflect the push.
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*/
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int push_node_right(struct ctree_root *root, struct ctree_path *path, int level)
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{
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int slot;
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@ -270,8 +269,11 @@ int push_node_right(struct ctree_root *root, struct ctree_path *path, int level)
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int dst_nritems;
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int src_nritems;
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/* can't push from the root */
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if (level == MAX_LEVEL - 1 || path->nodes[level + 1] == 0)
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return 1;
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/* only try to push inside the node higher up */
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slot = path->slots[level + 1];
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if (slot == NODEPTRS_PER_BLOCK - 1)
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return 1;
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@ -315,7 +317,7 @@ int push_node_right(struct ctree_root *root, struct ctree_path *path, int level)
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write_tree_block(root, t);
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write_tree_block(root, src_buffer);
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/* then fixup the leaf pointer in the path */
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/* then fixup the pointers in the path */
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if (path->slots[level] >= src->header.nritems) {
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path->slots[level] -= src->header.nritems;
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tree_block_release(root, path->nodes[level]);
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@ -327,6 +329,76 @@ int push_node_right(struct ctree_root *root, struct ctree_path *path, int level)
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return 0;
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}
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/*
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* worker function to insert a single pointer in a node.
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* the node should have enough room for the pointer already
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* slot and level indicate where you want the key to go, and
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* blocknr is the block the key points to.
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*/
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int __insert_ptr(struct ctree_root *root,
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struct ctree_path *path, struct key *key,
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u64 blocknr, int slot, int level)
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{
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struct node *c;
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struct node *lower;
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struct key *lower_key;
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int nritems;
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/* need a new root */
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if (!path->nodes[level]) {
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struct tree_buffer *t;
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t = alloc_free_block(root);
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c = &t->node;
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memset(c, 0, sizeof(c));
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c->header.nritems = 2;
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c->header.flags = node_level(level);
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c->header.blocknr = t->blocknr;
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lower = &path->nodes[level-1]->node;
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if (is_leaf(lower->header.flags))
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lower_key = &((struct leaf *)lower)->items[0].key;
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else
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lower_key = lower->keys;
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memcpy(c->keys, lower_key, sizeof(struct key));
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memcpy(c->keys + 1, key, sizeof(struct key));
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c->blockptrs[0] = path->nodes[level-1]->blocknr;
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c->blockptrs[1] = blocknr;
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/* the path has an extra ref to root->node */
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tree_block_release(root, root->node);
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root->node = t;
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t->count++;
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write_tree_block(root, t);
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path->nodes[level] = t;
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path->slots[level] = 0;
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if (c->keys[1].objectid == 0)
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BUG();
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return 0;
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}
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lower = &path->nodes[level]->node;
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nritems = lower->header.nritems;
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if (slot > nritems)
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BUG();
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if (nritems == NODEPTRS_PER_BLOCK)
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BUG();
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if (slot != nritems) {
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memmove(lower->keys + slot + 1, lower->keys + slot,
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(nritems - slot) * sizeof(struct key));
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memmove(lower->blockptrs + slot + 1, lower->blockptrs + slot,
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(nritems - slot) * sizeof(u64));
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}
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memcpy(lower->keys + slot, key, sizeof(struct key));
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lower->blockptrs[slot] = blocknr;
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lower->header.nritems++;
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if (lower->keys[1].objectid == 0)
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BUG();
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write_tree_block(root, path->nodes[level]);
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return 0;
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}
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/*
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* insert a key,blocknr pair into the tree at a given level
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* If the node at that level in the path doesn't have room,
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* it is split or shifted as appropriate.
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*/
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int insert_ptr(struct ctree_root *root,
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struct ctree_path *path, struct key *key,
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u64 blocknr, int level)
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@ -340,6 +412,15 @@ int insert_ptr(struct ctree_root *root,
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int mid;
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int bal_start = -1;
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/*
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* check to see if we need to make room in the node for this
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* pointer. If we do, keep walking the tree, making sure there
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* is enough room in each level for the required insertions.
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*
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* The bal array is filled in with any nodes to be inserted
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* due to splitting. Once we've done all the splitting required
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* do the inserts based on the data in the bal array.
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*/
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memset(bal, 0, ARRAY_SIZE(bal));
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while(t && t->node.header.nritems == NODEPTRS_PER_BLOCK) {
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c = &t->node;
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@ -373,6 +454,11 @@ int insert_ptr(struct ctree_root *root,
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bal_level += 1;
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t = path->nodes[bal_level];
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}
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/*
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* bal_start tells us the first level in the tree that needed to
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* be split. Go through the bal array inserting the new nodes
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* as needed. The path is fixed as we go.
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*/
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while(bal_start > 0) {
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b_buffer = bal[bal_start];
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c = &path->nodes[bal_start]->node;
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@ -390,10 +476,16 @@ int insert_ptr(struct ctree_root *root,
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if (!bal[bal_start])
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break;
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}
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/* Now that the tree has room, insert the requested pointer */
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return __insert_ptr(root, path, key, blocknr, path->slots[level] + 1,
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level);
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}
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/*
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* how many bytes are required to store the items in a leaf. start
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* and nr indicate which items in the leaf to check. This totals up the
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* space used both by the item structs and the item data
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*/
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int leaf_space_used(struct leaf *l, int start, int nr)
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{
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int data_len;
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@ -407,6 +499,10 @@ int leaf_space_used(struct leaf *l, int start, int nr)
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return data_len;
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}
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/*
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* push some data in the path leaf to the left, trying to free up at
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* least data_size bytes. returns zero if the push worked, nonzero otherwise
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*/
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int push_leaf_left(struct ctree_root *root, struct ctree_path *path,
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int data_size)
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{
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@ -498,6 +594,10 @@ int push_leaf_left(struct ctree_root *root, struct ctree_path *path,
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return 0;
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}
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/*
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* split the path's leaf in two, making sure there is at least data_size
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* available for the resulting leaf level of the path.
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*/
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int split_leaf(struct ctree_root *root, struct ctree_path *path, int data_size)
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{
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struct tree_buffer *l_buf = path->nodes[0];
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@ -548,9 +648,10 @@ int split_leaf(struct ctree_root *root, struct ctree_path *path, int data_size)
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l->data + leaf_data_end(l), data_copy_size);
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rt_data_off = LEAF_DATA_SIZE -
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(l->items[mid].offset + l->items[mid].size);
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for (i = 0; i < right->header.nritems; i++) {
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for (i = 0; i < right->header.nritems; i++)
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right->items[i].offset += rt_data_off;
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}
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l->header.nritems = mid;
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ret = insert_ptr(root, path, &right->items[0].key,
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right_buffer->blocknr, 1);
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@ -570,6 +671,10 @@ int split_leaf(struct ctree_root *root, struct ctree_path *path, int data_size)
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return ret;
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}
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/*
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* Given a key and some data, insert an item into the tree.
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* This does all the path init required, making room in the tree if needed.
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*/
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int insert_item(struct ctree_root *root, struct key *key,
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void *data, int data_size)
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{
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@ -582,6 +687,7 @@ int insert_item(struct ctree_root *root, struct key *key,
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unsigned int data_end;
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struct ctree_path path;
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/* create a root if there isn't one */
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if (!root->node) {
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struct tree_buffer *t;
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t = alloc_free_block(root);
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|
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@ -602,6 +708,8 @@ int insert_item(struct ctree_root *root, struct key *key,
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slot_orig = path.slots[0];
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leaf_buf = path.nodes[0];
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leaf = &leaf_buf->leaf;
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/* make room if needed */
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if (leaf_free_space(leaf) < sizeof(struct item) + data_size) {
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split_leaf(root, &path, data_size);
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leaf_buf = path.nodes[0];
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@ -638,6 +746,7 @@ int insert_item(struct ctree_root *root, struct key *key,
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data_end, old_data - data_end);
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data_end = old_data;
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}
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/* copy the new data in */
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memcpy(&leaf->items[slot].key, key, sizeof(struct key));
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leaf->items[slot].offset = data_end - data_size;
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leaf->items[slot].size = data_size;
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@ -650,6 +759,14 @@ int insert_item(struct ctree_root *root, struct key *key,
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return 0;
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}
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/*
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* delete the pointer from a given level in the path. The path is not
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* fixed up, so after calling this it is not valid at that level.
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||||
*
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* If the delete empties a node, the node is removed from the tree,
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* continuing all the way the root if required. The root is converted into
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* a leaf if all the nodes are emptied.
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*/
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int del_ptr(struct ctree_root *root, struct ctree_path *path, int level)
|
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{
|
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int slot;
|
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|
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@ -705,6 +822,10 @@ int del_ptr(struct ctree_root *root, struct ctree_path *path, int level)
|
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return 0;
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||||
}
|
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/*
|
||||
* delete the item at the leaf level in path. If that empties
|
||||
* the leaf, remove it from the tree
|
||||
*/
|
||||
int del_item(struct ctree_root *root, struct ctree_path *path)
|
||||
{
|
||||
int slot;
|
||||
|
|
@ -732,6 +853,7 @@ int del_item(struct ctree_root *root, struct ctree_path *path)
|
|||
(leaf->header.nritems - slot - 1));
|
||||
}
|
||||
leaf->header.nritems -= 1;
|
||||
/* delete the leaf if we've emptied it */
|
||||
if (leaf->header.nritems == 0) {
|
||||
if (leaf_buf == root->node) {
|
||||
leaf->header.flags = node_level(0);
|
||||
|
|
@ -742,6 +864,7 @@ int del_item(struct ctree_root *root, struct ctree_path *path)
|
|||
if (slot == 0)
|
||||
fixup_low_keys(root, path, &leaf->items[0].key, 1);
|
||||
write_tree_block(root, leaf_buf);
|
||||
/* delete the leaf if it is mostly empty */
|
||||
if (leaf_space_used(leaf, 0, leaf->header.nritems) <
|
||||
LEAF_DATA_SIZE / 4) {
|
||||
/* push_leaf_left fixes the path.
|
||||
|
|
@ -837,7 +960,7 @@ int main() {
|
|||
int i;
|
||||
int num;
|
||||
int ret;
|
||||
int run_size = 1000000;
|
||||
int run_size = 25000;
|
||||
int max_key = 100000000;
|
||||
int tree_size = 0;
|
||||
struct ctree_path path;
|
||||
|
|
|
|||
Загрузка…
Ссылка в новой задаче