3 #include "kerncompat.h"
4 #include "radix-tree.h"
7 #include "print-tree.h"
9 static int find_free_extent(struct ctree_root *orig_root, u64 num_blocks,
10 u64 search_start, u64 search_end, struct key *ins);
11 static int finish_current_insert(struct ctree_root *extent_root);
12 static int run_pending(struct ctree_root *extent_root);
15 * pending extents are blocks that we're trying to allocate in the extent
16 * map while trying to grow the map because of other allocations. To avoid
17 * recursing, they are tagged in the radix tree and cleaned up after
18 * other allocations are done. The pending tag is also used in the same
21 #define CTREE_EXTENT_PENDING_DEL 0
23 static int inc_block_ref(struct ctree_root *root, u64 blocknr)
25 struct ctree_path path;
29 struct extent_item *item;
32 find_free_extent(root->extent_root, 0, 0, (u64)-1, &ins);
34 key.objectid = blocknr;
37 ret = search_slot(root->extent_root, &key, &path, 0, 1);
41 l = &path.nodes[0]->leaf;
42 item = (struct extent_item *)(l->data +
43 l->items[path.slots[0]].offset);
46 BUG_ON(list_empty(&path.nodes[0]->dirty));
47 release_path(root->extent_root, &path);
48 finish_current_insert(root->extent_root);
49 run_pending(root->extent_root);
53 static int lookup_block_ref(struct ctree_root *root, u64 blocknr, u32 *refs)
55 struct ctree_path path;
59 struct extent_item *item;
61 key.objectid = blocknr;
64 ret = search_slot(root->extent_root, &key, &path, 0, 0);
67 l = &path.nodes[0]->leaf;
68 item = (struct extent_item *)(l->data +
69 l->items[path.slots[0]].offset);
71 release_path(root->extent_root, &path);
75 int btrfs_inc_ref(struct ctree_root *root, struct tree_buffer *buf)
80 if (root == root->extent_root)
82 if (btrfs_is_leaf(&buf->node))
85 for (i = 0; i < btrfs_header_nritems(&buf->node.header); i++) {
86 blocknr = buf->node.blockptrs[i];
87 inc_block_ref(root, blocknr);
92 int btrfs_finish_extent_commit(struct ctree_root *root)
94 struct ctree_root *extent_root = root->extent_root;
95 unsigned long gang[8];
100 ret = radix_tree_gang_lookup(&extent_root->pinned_radix,
105 for (i = 0; i < ret; i++) {
106 radix_tree_delete(&extent_root->pinned_radix, gang[i]);
109 extent_root->last_insert.objectid = 0;
110 extent_root->last_insert.offset = 0;
114 static int finish_current_insert(struct ctree_root *extent_root)
117 struct extent_item extent_item;
121 extent_item.refs = 1;
123 btrfs_header_parentid(&extent_root->node->node.header);
127 for (i = 0; i < extent_root->current_insert.flags; i++) {
128 ins.objectid = extent_root->current_insert.objectid + i;
129 ret = insert_item(extent_root, &ins, &extent_item,
130 sizeof(extent_item));
133 extent_root->current_insert.offset = 0;
138 * remove an extent from the root, returns 0 on success
140 int __free_extent(struct ctree_root *root, u64 blocknr, u64 num_blocks)
142 struct ctree_path path;
144 struct ctree_root *extent_root = root->extent_root;
147 struct extent_item *ei;
150 key.objectid = blocknr;
152 key.offset = num_blocks;
154 find_free_extent(root, 0, 0, (u64)-1, &ins);
156 ret = search_slot(extent_root, &key, &path, -1, 1);
158 printf("failed to find %Lu\n", key.objectid);
159 print_tree(extent_root, extent_root->node);
160 printf("failed to find %Lu\n", key.objectid);
163 item = path.nodes[0]->leaf.items + path.slots[0];
164 ei = (struct extent_item *)(path.nodes[0]->leaf.data + item->offset);
165 BUG_ON(ei->refs == 0);
168 if (root == extent_root) {
170 radix_tree_preload(GFP_KERNEL);
171 err = radix_tree_insert(&extent_root->pinned_radix,
172 blocknr, (void *)blocknr);
174 radix_tree_preload_end();
176 ret = del_item(extent_root, &path);
177 if (root != extent_root &&
178 extent_root->last_insert.objectid < blocknr)
179 extent_root->last_insert.objectid = blocknr;
183 release_path(extent_root, &path);
184 finish_current_insert(extent_root);
189 * find all the blocks marked as pending in the radix tree and remove
190 * them from the extent map
192 static int del_pending_extents(struct ctree_root *extent_root)
195 struct tree_buffer *gang[4];
199 ret = radix_tree_gang_lookup_tag(&extent_root->cache_radix,
202 CTREE_EXTENT_PENDING_DEL);
205 for (i = 0; i < ret; i++) {
206 ret = __free_extent(extent_root, gang[i]->blocknr, 1);
207 radix_tree_tag_clear(&extent_root->cache_radix,
209 CTREE_EXTENT_PENDING_DEL);
210 tree_block_release(extent_root, gang[i]);
216 static int run_pending(struct ctree_root *extent_root)
218 while(radix_tree_tagged(&extent_root->cache_radix,
219 CTREE_EXTENT_PENDING_DEL))
220 del_pending_extents(extent_root);
226 * remove an extent from the root, returns 0 on success
228 int free_extent(struct ctree_root *root, u64 blocknr, u64 num_blocks)
231 struct ctree_root *extent_root = root->extent_root;
232 struct tree_buffer *t;
236 if (root == extent_root) {
237 t = find_tree_block(root, blocknr);
238 radix_tree_tag_set(&root->cache_radix, blocknr,
239 CTREE_EXTENT_PENDING_DEL);
242 key.objectid = blocknr;
244 key.offset = num_blocks;
245 ret = __free_extent(root, blocknr, num_blocks);
246 pending_ret = run_pending(root->extent_root);
247 return ret ? ret : pending_ret;
251 * walks the btree of allocated extents and find a hole of a given size.
252 * The key ins is changed to record the hole:
253 * ins->objectid == block start
255 * ins->offset == number of blocks
256 * Any available blocks before search_start are skipped.
258 static int find_free_extent(struct ctree_root *orig_root, u64 num_blocks,
259 u64 search_start, u64 search_end, struct key *ins)
261 struct ctree_path path;
270 struct ctree_root * root = orig_root->extent_root;
271 int total_needed = num_blocks;
273 total_needed += (btrfs_header_level(&root->node->node.header) + 1) * 3;
274 if (root->last_insert.objectid > search_start)
275 search_start = root->last_insert.objectid;
278 ins->objectid = search_start;
282 ret = search_slot(root, ins, &path, 0, 0);
286 if (path.slots[0] > 0)
290 l = &path.nodes[0]->leaf;
291 slot = path.slots[0];
292 if (slot >= btrfs_header_nritems(&l->header)) {
293 ret = next_leaf(root, &path);
299 ins->objectid = search_start;
300 ins->offset = (u64)-1;
304 ins->objectid = last_block > search_start ?
305 last_block : search_start;
306 ins->offset = (u64)-1;
309 key = &l->items[slot].key;
310 if (key->objectid >= search_start) {
312 if (last_block < search_start)
313 last_block = search_start;
314 hole_size = key->objectid - last_block;
315 if (hole_size > total_needed) {
316 ins->objectid = last_block;
317 ins->offset = hole_size;
323 last_block = key->objectid + key->offset;
328 /* we have to make sure we didn't find an extent that has already
329 * been allocated by the map tree or the original allocation
331 release_path(root, &path);
332 BUG_ON(ins->objectid < search_start);
333 for (test_block = ins->objectid;
334 test_block < ins->objectid + total_needed; test_block++) {
335 if (radix_tree_lookup(&root->pinned_radix, test_block)) {
336 search_start = test_block + 1;
340 BUG_ON(root->current_insert.offset);
341 root->current_insert.offset = total_needed - num_blocks;
342 root->current_insert.objectid = ins->objectid + num_blocks;
343 root->current_insert.flags = 0;
344 root->last_insert.objectid = ins->objectid;
345 ins->offset = num_blocks;
348 release_path(root, &path);
353 * finds a free extent and does all the dirty work required for allocation
354 * returns the key for the extent through ins, and a tree buffer for
355 * the first block of the extent through buf.
357 * returns 0 if everything worked, non-zero otherwise.
359 int alloc_extent(struct ctree_root *root, u64 num_blocks, u64 search_start,
360 u64 search_end, u64 owner, struct key *ins)
364 struct ctree_root *extent_root = root->extent_root;
365 struct extent_item extent_item;
367 extent_item.refs = 1;
368 extent_item.owner = owner;
370 if (root == extent_root) {
371 BUG_ON(extent_root->current_insert.offset == 0);
372 BUG_ON(num_blocks != 1);
373 BUG_ON(extent_root->current_insert.flags ==
374 extent_root->current_insert.offset);
376 ins->objectid = extent_root->current_insert.objectid +
377 extent_root->current_insert.flags++;
380 ret = find_free_extent(root, num_blocks, search_start,
385 ret = insert_item(extent_root, ins, &extent_item,
386 sizeof(extent_item));
388 finish_current_insert(extent_root);
389 pending_ret = run_pending(extent_root);
398 * helper function to allocate a block for a given tree
399 * returns the tree buffer or NULL.
401 struct tree_buffer *alloc_free_block(struct ctree_root *root)
405 struct tree_buffer *buf;
407 ret = alloc_extent(root, 1, 0, (unsigned long)-1,
408 btrfs_header_parentid(&root->node->node.header),
414 buf = find_tree_block(root, ins.objectid);
415 dirty_tree_block(root, buf);
419 int walk_down_tree(struct ctree_root *root, struct ctree_path *path, int *level)
421 struct tree_buffer *next;
422 struct tree_buffer *cur;
427 ret = lookup_block_ref(root, path->nodes[*level]->blocknr, &refs);
432 cur = path->nodes[*level];
433 if (path->slots[*level] >=
434 btrfs_header_nritems(&cur->node.header))
436 blocknr = cur->node.blockptrs[path->slots[*level]];
437 ret = lookup_block_ref(root, blocknr, &refs);
438 if (refs != 1 || *level == 1) {
439 path->slots[*level]++;
440 ret = free_extent(root, blocknr, 1);
445 next = read_tree_block(root, blocknr);
446 if (path->nodes[*level-1])
447 tree_block_release(root, path->nodes[*level-1]);
448 path->nodes[*level-1] = next;
449 *level = btrfs_header_level(&next->node.header);
450 path->slots[*level] = 0;
453 ret = free_extent(root, path->nodes[*level]->blocknr, 1);
454 tree_block_release(root, path->nodes[*level]);
455 path->nodes[*level] = NULL;
461 int walk_up_tree(struct ctree_root *root, struct ctree_path *path, int *level)
466 for(i = *level; i < MAX_LEVEL - 1 && path->nodes[i]; i++) {
467 slot = path->slots[i];
469 btrfs_header_nritems(&path->nodes[i]->node.header)- 1) {
474 ret = free_extent(root,
475 path->nodes[*level]->blocknr, 1);
476 tree_block_release(root, path->nodes[*level]);
477 path->nodes[*level] = NULL;
485 int btrfs_drop_snapshot(struct ctree_root *root, struct tree_buffer *snap)
489 struct ctree_path path;
495 level = btrfs_header_level(&snap->node.header);
497 path.nodes[level] = snap;
498 path.slots[level] = 0;
500 ret = walk_down_tree(root, &path, &level);
503 ret = walk_up_tree(root, &path, &level);
507 for (i = 0; i <= orig_level; i++) {
509 tree_block_release(root, path.nodes[i]);