442 lines
11 KiB
C
442 lines
11 KiB
C
#include <stdio.h>
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#include <stdlib.h>
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#include "kerncompat.h"
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#include "radix-tree.h"
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#include "ctree.h"
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#include "disk-io.h"
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#include "print-tree.h"
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static int find_free_extent(struct ctree_root *orig_root, u64 num_blocks,
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u64 search_start, u64 search_end, struct key *ins);
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static int finish_current_insert(struct ctree_root *extent_root);
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static int run_pending(struct ctree_root *extent_root);
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/*
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* pending extents are blocks that we're trying to allocate in the extent
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* map while trying to grow the map because of other allocations. To avoid
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* recursing, they are tagged in the radix tree and cleaned up after
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* other allocations are done. The pending tag is also used in the same
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* manner for deletes.
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*/
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#define CTREE_EXTENT_PENDING_DEL 0
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static int inc_block_ref(struct ctree_root *root, u64 blocknr)
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{
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struct ctree_path path;
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int ret;
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struct key key;
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struct leaf *l;
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struct extent_item *item;
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struct key ins;
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find_free_extent(root->extent_root, 0, 0, (u64)-1, &ins);
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init_path(&path);
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key.objectid = blocknr;
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key.flags = 0;
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key.offset = 1;
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ret = search_slot(root->extent_root, &key, &path, 0, 1);
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if (ret != 0)
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BUG();
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BUG_ON(ret != 0);
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l = &path.nodes[0]->leaf;
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item = (struct extent_item *)(l->data +
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l->items[path.slots[0]].offset);
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item->refs++;
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BUG_ON(list_empty(&path.nodes[0]->dirty));
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release_path(root->extent_root, &path);
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finish_current_insert(root->extent_root);
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run_pending(root->extent_root);
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return 0;
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}
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static int lookup_block_ref(struct ctree_root *root, u64 blocknr, int *refs)
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{
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struct ctree_path path;
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int ret;
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struct key key;
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struct leaf *l;
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struct extent_item *item;
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init_path(&path);
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key.objectid = blocknr;
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key.flags = 0;
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key.offset = 1;
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ret = search_slot(root->extent_root, &key, &path, 0, 0);
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if (ret != 0)
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BUG();
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l = &path.nodes[0]->leaf;
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item = (struct extent_item *)(l->data +
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l->items[path.slots[0]].offset);
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*refs = item->refs;
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release_path(root->extent_root, &path);
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return 0;
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}
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int btrfs_inc_ref(struct ctree_root *root, struct tree_buffer *buf)
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{
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u64 blocknr;
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int i;
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if (root == root->extent_root)
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return 0;
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if (is_leaf(buf->node.header.flags))
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return 0;
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for (i = 0; i < buf->node.header.nritems; i++) {
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blocknr = buf->node.blockptrs[i];
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inc_block_ref(root, blocknr);
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}
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return 0;
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}
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int btrfs_finish_extent_commit(struct ctree_root *root)
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{
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struct ctree_root *extent_root = root->extent_root;
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unsigned long gang[8];
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int ret;
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int i;
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while(1) {
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ret = radix_tree_gang_lookup(&extent_root->pinned_radix,
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(void **)gang, 0,
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ARRAY_SIZE(gang));
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if (!ret)
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break;
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for (i = 0; i < ret; i++)
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radix_tree_delete(&extent_root->pinned_radix, gang[i]);
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}
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return 0;
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}
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static int finish_current_insert(struct ctree_root *extent_root)
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{
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struct key ins;
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struct extent_item extent_item;
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int i;
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int ret;
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extent_item.refs = 1;
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extent_item.owner = extent_root->node->node.header.parentid;
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ins.offset = 1;
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ins.flags = 0;
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for (i = 0; i < extent_root->current_insert.flags; i++) {
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ins.objectid = extent_root->current_insert.objectid + i;
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ret = insert_item(extent_root, &ins, &extent_item,
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sizeof(extent_item));
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BUG_ON(ret);
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}
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extent_root->current_insert.offset = 0;
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return 0;
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}
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/*
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* remove an extent from the root, returns 0 on success
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*/
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int __free_extent(struct ctree_root *root, u64 blocknr, u64 num_blocks)
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{
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struct ctree_path path;
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struct key key;
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struct ctree_root *extent_root = root->extent_root;
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int ret;
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struct item *item;
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struct extent_item *ei;
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struct key ins;
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key.objectid = blocknr;
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key.flags = 0;
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key.offset = num_blocks;
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find_free_extent(root, 0, 0, (u64)-1, &ins);
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init_path(&path);
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ret = search_slot(extent_root, &key, &path, -1, 1);
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if (ret) {
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printf("failed to find %Lu\n", key.objectid);
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print_tree(extent_root, extent_root->node);
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printf("failed to find %Lu\n", key.objectid);
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BUG();
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}
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item = path.nodes[0]->leaf.items + path.slots[0];
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ei = (struct extent_item *)(path.nodes[0]->leaf.data + item->offset);
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BUG_ON(ei->refs == 0);
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ei->refs--;
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if (ei->refs == 0) {
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if (root == extent_root) {
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int err;
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radix_tree_preload(GFP_KERNEL);
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err = radix_tree_insert(&extent_root->pinned_radix,
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blocknr, (void *)blocknr);
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BUG_ON(err);
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radix_tree_preload_end();
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}
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ret = del_item(extent_root, &path);
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if (ret)
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BUG();
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}
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release_path(extent_root, &path);
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finish_current_insert(extent_root);
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return ret;
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}
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/*
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* find all the blocks marked as pending in the radix tree and remove
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* them from the extent map
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*/
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static int del_pending_extents(struct ctree_root *extent_root)
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{
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int ret;
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struct tree_buffer *gang[4];
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int i;
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while(1) {
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ret = radix_tree_gang_lookup_tag(&extent_root->cache_radix,
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(void **)gang, 0,
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ARRAY_SIZE(gang),
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CTREE_EXTENT_PENDING_DEL);
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if (!ret)
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break;
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for (i = 0; i < ret; i++) {
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ret = __free_extent(extent_root, gang[i]->blocknr, 1);
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radix_tree_tag_clear(&extent_root->cache_radix,
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gang[i]->blocknr,
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CTREE_EXTENT_PENDING_DEL);
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tree_block_release(extent_root, gang[i]);
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}
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}
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return 0;
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}
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static int run_pending(struct ctree_root *extent_root)
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{
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while(radix_tree_tagged(&extent_root->cache_radix,
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CTREE_EXTENT_PENDING_DEL))
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del_pending_extents(extent_root);
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return 0;
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}
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/*
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* remove an extent from the root, returns 0 on success
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*/
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int free_extent(struct ctree_root *root, u64 blocknr, u64 num_blocks)
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{
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struct key key;
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struct ctree_root *extent_root = root->extent_root;
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struct tree_buffer *t;
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int pending_ret;
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int ret;
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if (root == extent_root) {
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t = find_tree_block(root, blocknr);
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radix_tree_tag_set(&root->cache_radix, blocknr,
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CTREE_EXTENT_PENDING_DEL);
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return 0;
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}
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key.objectid = blocknr;
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key.flags = 0;
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key.offset = num_blocks;
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ret = __free_extent(root, blocknr, num_blocks);
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pending_ret = run_pending(root->extent_root);
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return ret ? ret : pending_ret;
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}
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/*
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* walks the btree of allocated extents and find a hole of a given size.
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* The key ins is changed to record the hole:
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* ins->objectid == block start
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* ins->flags = 0
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* ins->offset == number of blocks
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* Any available blocks before search_start are skipped.
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*/
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static int find_free_extent(struct ctree_root *orig_root, u64 num_blocks,
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u64 search_start, u64 search_end, struct key *ins)
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{
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struct ctree_path path;
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struct key *key;
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int ret;
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u64 hole_size = 0;
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int slot = 0;
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u64 last_block;
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u64 test_block;
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int start_found;
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struct leaf *l;
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struct ctree_root * root = orig_root->extent_root;
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int total_needed = num_blocks + MAX_LEVEL * 3;
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check_failed:
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init_path(&path);
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ins->objectid = search_start;
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ins->offset = 0;
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ins->flags = 0;
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start_found = 0;
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ret = search_slot(root, ins, &path, 0, 0);
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if (ret < 0)
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goto error;
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while (1) {
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l = &path.nodes[0]->leaf;
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slot = path.slots[0];
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if (slot >= l->header.nritems) {
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ret = next_leaf(root, &path);
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if (ret == 0)
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continue;
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if (ret < 0)
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goto error;
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if (!start_found) {
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ins->objectid = search_start;
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ins->offset = (u64)-1;
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start_found = 1;
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goto check_pending;
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}
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ins->objectid = last_block > search_start ?
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last_block : search_start;
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ins->offset = (u64)-1;
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goto check_pending;
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}
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if (slot == 0) {
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int last_slot = l->header.nritems - 1;
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u64 span = l->items[last_slot].key.objectid;
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span -= l->items[slot].key.objectid;
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if (span + total_needed > last_slot - slot) {
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path.slots[0] = last_slot + 1;
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key = &l->items[last_slot].key;
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last_block = key->objectid + key->offset;
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start_found = 1;
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continue;
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}
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}
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key = &l->items[slot].key;
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if (key->objectid >= search_start) {
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if (start_found) {
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hole_size = key->objectid - last_block;
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if (hole_size > total_needed) {
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ins->objectid = last_block;
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ins->offset = hole_size;
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goto check_pending;
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}
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} else
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start_found = 1;
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last_block = key->objectid + key->offset;
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}
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path.slots[0]++;
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}
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// FIXME -ENOSPC
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check_pending:
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/* we have to make sure we didn't find an extent that has already
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* been allocated by the map tree or the original allocation
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*/
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release_path(root, &path);
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BUG_ON(ins->objectid < search_start);
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for (test_block = ins->objectid;
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test_block < ins->objectid + total_needed; test_block++) {
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if (radix_tree_lookup(&root->pinned_radix, test_block)) {
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search_start = test_block + 1;
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goto check_failed;
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}
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}
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BUG_ON(root->current_insert.offset);
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root->current_insert.offset = total_needed;
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root->current_insert.objectid = ins->objectid + num_blocks;
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root->current_insert.flags = 0;
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ins->offset = num_blocks;
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return 0;
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error:
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release_path(root, &path);
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return ret;
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}
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/*
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* finds a free extent and does all the dirty work required for allocation
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* returns the key for the extent through ins, and a tree buffer for
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* the first block of the extent through buf.
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*
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* returns 0 if everything worked, non-zero otherwise.
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*/
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int alloc_extent(struct ctree_root *root, u64 num_blocks, u64 search_start,
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u64 search_end, u64 owner, struct key *ins)
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{
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int ret;
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int pending_ret;
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struct ctree_root *extent_root = root->extent_root;
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struct extent_item extent_item;
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extent_item.refs = 1;
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extent_item.owner = owner;
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if (root == extent_root) {
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BUG_ON(extent_root->current_insert.offset == 0);
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BUG_ON(num_blocks != 1);
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BUG_ON(extent_root->current_insert.flags ==
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extent_root->current_insert.offset);
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ins->offset = 1;
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ins->objectid = extent_root->current_insert.objectid +
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extent_root->current_insert.flags++;
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return 0;
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}
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ret = find_free_extent(root, num_blocks, search_start,
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search_end, ins);
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if (ret)
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return ret;
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ret = insert_item(extent_root, ins, &extent_item,
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sizeof(extent_item));
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finish_current_insert(extent_root);
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pending_ret = run_pending(extent_root);
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if (ret)
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return ret;
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if (pending_ret)
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return pending_ret;
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return 0;
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}
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/*
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* helper function to allocate a block for a given tree
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* returns the tree buffer or NULL.
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*/
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struct tree_buffer *alloc_free_block(struct ctree_root *root)
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{
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struct key ins;
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int ret;
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struct tree_buffer *buf;
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ret = alloc_extent(root, 1, 0, (unsigned long)-1,
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root->node->node.header.parentid,
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&ins);
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if (ret) {
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BUG();
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return NULL;
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}
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buf = find_tree_block(root, ins.objectid);
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dirty_tree_block(root, buf);
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return buf;
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}
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int btrfs_drop_snapshot(struct ctree_root *root, struct tree_buffer *snap)
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{
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int ret;
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int level;
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int refs;
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u64 blocknr = snap->blocknr;
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level = node_level(snap->node.header.flags);
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ret = lookup_block_ref(root, snap->blocknr, &refs);
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BUG_ON(ret);
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if (refs == 1 && level != 0) {
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struct node *n = &snap->node;
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struct tree_buffer *b;
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int i;
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for (i = 0; i < n->header.nritems; i++) {
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b = read_tree_block(root, n->blockptrs[i]);
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/* FIXME, don't recurse here */
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ret = btrfs_drop_snapshot(root, b);
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BUG_ON(ret);
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tree_block_release(root, b);
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}
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}
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ret = free_extent(root, blocknr, 1);
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BUG_ON(ret);
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return 0;
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}
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