3 #include "kerncompat.h"
4 #include "radix-tree.h"
7 #include "print-tree.h"
9 static int find_free_extent(struct btrfs_root *orig_root, u64 num_blocks,
10 u64 search_start, u64 search_end,
11 struct btrfs_key *ins);
12 static int finish_current_insert(struct btrfs_root *extent_root);
13 static int run_pending(struct btrfs_root *extent_root);
16 * pending extents are blocks that we're trying to allocate in the extent
17 * map while trying to grow the map because of other allocations. To avoid
18 * recursing, they are tagged in the radix tree and cleaned up after
19 * other allocations are done. The pending tag is also used in the same
22 #define CTREE_EXTENT_PENDING_DEL 0
24 static int inc_block_ref(struct btrfs_root *root, u64 blocknr)
26 struct btrfs_path path;
30 struct btrfs_extent_item *item;
34 find_free_extent(root->extent_root, 0, 0, (u64)-1, &ins);
35 btrfs_init_path(&path);
36 key.objectid = blocknr;
39 ret = btrfs_search_slot(root->extent_root, &key, &path, 0, 1);
43 l = &path.nodes[0]->leaf;
44 item = (struct btrfs_extent_item *)(l->data +
45 btrfs_item_offset(l->items +
47 refs = btrfs_extent_refs(item);
48 btrfs_set_extent_refs(item, refs + 1);
50 BUG_ON(list_empty(&path.nodes[0]->dirty));
51 btrfs_release_path(root->extent_root, &path);
52 finish_current_insert(root->extent_root);
53 run_pending(root->extent_root);
57 static int lookup_block_ref(struct btrfs_root *root, u64 blocknr, u32 *refs)
59 struct btrfs_path path;
63 struct btrfs_extent_item *item;
64 btrfs_init_path(&path);
65 key.objectid = blocknr;
68 ret = btrfs_search_slot(root->extent_root, &key, &path, 0, 0);
71 l = &path.nodes[0]->leaf;
72 item = (struct btrfs_extent_item *)(l->data +
73 btrfs_item_offset(l->items +
75 *refs = btrfs_extent_refs(item);
76 btrfs_release_path(root->extent_root, &path);
80 int btrfs_inc_ref(struct btrfs_root *root, struct btrfs_buffer *buf)
85 if (root == root->extent_root)
87 if (btrfs_is_leaf(&buf->node))
90 for (i = 0; i < btrfs_header_nritems(&buf->node.header); i++) {
91 blocknr = btrfs_node_blockptr(&buf->node, i);
92 inc_block_ref(root, blocknr);
97 int btrfs_finish_extent_commit(struct btrfs_root *root)
99 struct btrfs_root *extent_root = root->extent_root;
100 unsigned long gang[8];
105 ret = radix_tree_gang_lookup(&extent_root->pinned_radix,
110 for (i = 0; i < ret; i++) {
111 radix_tree_delete(&extent_root->pinned_radix, gang[i]);
114 extent_root->last_insert.objectid = 0;
115 extent_root->last_insert.offset = 0;
119 static int finish_current_insert(struct btrfs_root *extent_root)
121 struct btrfs_key ins;
122 struct btrfs_extent_item extent_item;
126 btrfs_set_extent_refs(&extent_item, 1);
127 btrfs_set_extent_owner(&extent_item,
128 btrfs_header_parentid(&extent_root->node->node.header));
132 for (i = 0; i < extent_root->current_insert.flags; i++) {
133 ins.objectid = extent_root->current_insert.objectid + i;
134 ret = btrfs_insert_item(extent_root, &ins, &extent_item,
135 sizeof(extent_item));
138 extent_root->current_insert.offset = 0;
143 * remove an extent from the root, returns 0 on success
145 static int __free_extent(struct btrfs_root *root, u64 blocknr, u64 num_blocks)
147 struct btrfs_path path;
148 struct btrfs_key key;
149 struct btrfs_root *extent_root = root->extent_root;
151 struct btrfs_item *item;
152 struct btrfs_extent_item *ei;
153 struct btrfs_key ins;
156 key.objectid = blocknr;
158 key.offset = num_blocks;
160 find_free_extent(root, 0, 0, (u64)-1, &ins);
161 btrfs_init_path(&path);
162 ret = btrfs_search_slot(extent_root, &key, &path, -1, 1);
164 printf("failed to find %Lu\n", key.objectid);
165 btrfs_print_tree(extent_root, extent_root->node);
166 printf("failed to find %Lu\n", key.objectid);
169 item = path.nodes[0]->leaf.items + path.slots[0];
170 ei = (struct btrfs_extent_item *)(path.nodes[0]->leaf.data +
171 btrfs_item_offset(item));
172 BUG_ON(ei->refs == 0);
173 refs = btrfs_extent_refs(ei) - 1;
174 btrfs_set_extent_refs(ei, refs);
176 if (root == extent_root) {
178 radix_tree_preload(GFP_KERNEL);
179 err = radix_tree_insert(&extent_root->pinned_radix,
180 blocknr, (void *)blocknr);
182 radix_tree_preload_end();
184 ret = btrfs_del_item(extent_root, &path);
185 if (root != extent_root &&
186 extent_root->last_insert.objectid < blocknr)
187 extent_root->last_insert.objectid = blocknr;
191 btrfs_release_path(extent_root, &path);
192 finish_current_insert(extent_root);
197 * find all the blocks marked as pending in the radix tree and remove
198 * them from the extent map
200 static int del_pending_extents(struct btrfs_root *extent_root)
203 struct btrfs_buffer *gang[4];
207 ret = radix_tree_gang_lookup_tag(&extent_root->cache_radix,
210 CTREE_EXTENT_PENDING_DEL);
213 for (i = 0; i < ret; i++) {
214 ret = __free_extent(extent_root, gang[i]->blocknr, 1);
215 radix_tree_tag_clear(&extent_root->cache_radix,
217 CTREE_EXTENT_PENDING_DEL);
218 btrfs_block_release(extent_root, gang[i]);
224 static int run_pending(struct btrfs_root *extent_root)
226 while(radix_tree_tagged(&extent_root->cache_radix,
227 CTREE_EXTENT_PENDING_DEL))
228 del_pending_extents(extent_root);
234 * remove an extent from the root, returns 0 on success
236 int btrfs_free_extent(struct btrfs_root *root, u64 blocknr, u64 num_blocks)
238 struct btrfs_key key;
239 struct btrfs_root *extent_root = root->extent_root;
240 struct btrfs_buffer *t;
244 if (root == extent_root) {
245 t = find_tree_block(root, blocknr);
246 radix_tree_tag_set(&root->cache_radix, blocknr,
247 CTREE_EXTENT_PENDING_DEL);
250 key.objectid = blocknr;
252 key.offset = num_blocks;
253 ret = __free_extent(root, blocknr, num_blocks);
254 pending_ret = run_pending(root->extent_root);
255 return ret ? ret : pending_ret;
259 * walks the btree of allocated extents and find a hole of a given size.
260 * The key ins is changed to record the hole:
261 * ins->objectid == block start
263 * ins->offset == number of blocks
264 * Any available blocks before search_start are skipped.
266 static int find_free_extent(struct btrfs_root *orig_root, u64 num_blocks,
267 u64 search_start, u64 search_end,
268 struct btrfs_key *ins)
270 struct btrfs_path path;
271 struct btrfs_key key;
278 struct btrfs_leaf *l;
279 struct btrfs_root * root = orig_root->extent_root;
280 int total_needed = num_blocks;
282 total_needed += (btrfs_header_level(&root->node->node.header) + 1) * 3;
283 if (root->last_insert.objectid > search_start)
284 search_start = root->last_insert.objectid;
286 btrfs_init_path(&path);
287 ins->objectid = search_start;
291 ret = btrfs_search_slot(root, ins, &path, 0, 0);
295 if (path.slots[0] > 0)
299 l = &path.nodes[0]->leaf;
300 slot = path.slots[0];
301 if (slot >= btrfs_header_nritems(&l->header)) {
302 ret = btrfs_next_leaf(root, &path);
308 ins->objectid = search_start;
309 ins->offset = (u64)-1;
313 ins->objectid = last_block > search_start ?
314 last_block : search_start;
315 ins->offset = (u64)-1;
318 btrfs_disk_key_to_cpu(&key, &l->items[slot].key);
319 if (key.objectid >= search_start) {
321 if (last_block < search_start)
322 last_block = search_start;
323 hole_size = key.objectid - last_block;
324 if (hole_size > total_needed) {
325 ins->objectid = last_block;
326 ins->offset = hole_size;
332 last_block = key.objectid + key.offset;
337 /* we have to make sure we didn't find an extent that has already
338 * been allocated by the map tree or the original allocation
340 btrfs_release_path(root, &path);
341 BUG_ON(ins->objectid < search_start);
342 for (test_block = ins->objectid;
343 test_block < ins->objectid + total_needed; test_block++) {
344 if (radix_tree_lookup(&root->pinned_radix, test_block)) {
345 search_start = test_block + 1;
349 BUG_ON(root->current_insert.offset);
350 root->current_insert.offset = total_needed - num_blocks;
351 root->current_insert.objectid = ins->objectid + num_blocks;
352 root->current_insert.flags = 0;
353 root->last_insert.objectid = ins->objectid;
354 ins->offset = num_blocks;
357 btrfs_release_path(root, &path);
362 * finds a free extent and does all the dirty work required for allocation
363 * returns the key for the extent through ins, and a tree buffer for
364 * the first block of the extent through buf.
366 * returns 0 if everything worked, non-zero otherwise.
368 int alloc_extent(struct btrfs_root *root, u64 num_blocks, u64 search_start,
369 u64 search_end, u64 owner, struct btrfs_key *ins)
373 struct btrfs_root *extent_root = root->extent_root;
374 struct btrfs_extent_item extent_item;
376 btrfs_set_extent_refs(&extent_item, 1);
377 btrfs_set_extent_owner(&extent_item, owner);
379 if (root == extent_root) {
380 BUG_ON(extent_root->current_insert.offset == 0);
381 BUG_ON(num_blocks != 1);
382 BUG_ON(extent_root->current_insert.flags ==
383 extent_root->current_insert.offset);
385 ins->objectid = extent_root->current_insert.objectid +
386 extent_root->current_insert.flags++;
389 ret = find_free_extent(root, num_blocks, search_start,
394 ret = btrfs_insert_item(extent_root, ins, &extent_item,
395 sizeof(extent_item));
397 finish_current_insert(extent_root);
398 pending_ret = run_pending(extent_root);
407 * helper function to allocate a block for a given tree
408 * returns the tree buffer or NULL.
410 struct btrfs_buffer *btrfs_alloc_free_block(struct btrfs_root *root)
412 struct btrfs_key ins;
414 struct btrfs_buffer *buf;
416 ret = alloc_extent(root, 1, 0, (unsigned long)-1,
417 btrfs_header_parentid(&root->node->node.header),
423 buf = find_tree_block(root, ins.objectid);
424 dirty_tree_block(root, buf);
428 int walk_down_tree(struct btrfs_root *root, struct btrfs_path *path, int *level)
430 struct btrfs_buffer *next;
431 struct btrfs_buffer *cur;
436 ret = lookup_block_ref(root, path->nodes[*level]->blocknr, &refs);
441 cur = path->nodes[*level];
442 if (path->slots[*level] >=
443 btrfs_header_nritems(&cur->node.header))
445 blocknr = btrfs_node_blockptr(&cur->node, path->slots[*level]);
446 ret = lookup_block_ref(root, blocknr, &refs);
447 if (refs != 1 || *level == 1) {
448 path->slots[*level]++;
449 ret = btrfs_free_extent(root, blocknr, 1);
454 next = read_tree_block(root, blocknr);
455 if (path->nodes[*level-1])
456 btrfs_block_release(root, path->nodes[*level-1]);
457 path->nodes[*level-1] = next;
458 *level = btrfs_header_level(&next->node.header);
459 path->slots[*level] = 0;
462 ret = btrfs_free_extent(root, path->nodes[*level]->blocknr, 1);
463 btrfs_block_release(root, path->nodes[*level]);
464 path->nodes[*level] = NULL;
470 int walk_up_tree(struct btrfs_root *root, struct btrfs_path *path, int *level)
475 for(i = *level; i < BTRFS_MAX_LEVEL - 1 && path->nodes[i]; i++) {
476 slot = path->slots[i];
478 btrfs_header_nritems(&path->nodes[i]->node.header)- 1) {
483 ret = btrfs_free_extent(root,
484 path->nodes[*level]->blocknr, 1);
485 btrfs_block_release(root, path->nodes[*level]);
486 path->nodes[*level] = NULL;
494 int btrfs_drop_snapshot(struct btrfs_root *root, struct btrfs_buffer *snap)
498 struct btrfs_path path;
502 btrfs_init_path(&path);
504 level = btrfs_header_level(&snap->node.header);
506 path.nodes[level] = snap;
507 path.slots[level] = 0;
509 ret = walk_down_tree(root, &path, &level);
512 ret = walk_up_tree(root, &path, &level);
516 for (i = 0; i <= orig_level; i++) {
518 btrfs_block_release(root, path.nodes[i]);