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)
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 unsigned long gang[8];
104 ret = radix_tree_gang_lookup(&root->pinned_radix,
109 for (i = 0; i < ret; i++) {
110 radix_tree_delete(&root->pinned_radix, gang[i]);
113 root->last_insert.objectid = 0;
114 root->last_insert.offset = 0;
118 static int finish_current_insert(struct btrfs_root *extent_root)
120 struct btrfs_key ins;
121 struct btrfs_extent_item extent_item;
125 btrfs_set_extent_refs(&extent_item, 1);
126 btrfs_set_extent_owner(&extent_item,
127 btrfs_header_parentid(&extent_root->node->node.header));
131 for (i = 0; i < extent_root->current_insert.flags; i++) {
132 ins.objectid = extent_root->current_insert.objectid + i;
133 ret = btrfs_insert_item(extent_root, &ins, &extent_item,
134 sizeof(extent_item));
137 extent_root->current_insert.offset = 0;
142 * remove an extent from the root, returns 0 on success
144 static int __free_extent(struct btrfs_root *root, u64 blocknr, u64 num_blocks)
146 struct btrfs_path path;
147 struct btrfs_key key;
148 struct btrfs_root *extent_root = root->extent_root;
150 struct btrfs_item *item;
151 struct btrfs_extent_item *ei;
152 struct btrfs_key ins;
155 key.objectid = blocknr;
157 key.offset = num_blocks;
159 find_free_extent(root, 0, 0, (u64)-1, &ins);
160 btrfs_init_path(&path);
161 ret = btrfs_search_slot(extent_root, &key, &path, -1, 1);
163 printf("failed to find %Lu\n", key.objectid);
164 btrfs_print_tree(extent_root, extent_root->node);
165 printf("failed to find %Lu\n", key.objectid);
168 item = path.nodes[0]->leaf.items + path.slots[0];
169 ei = (struct btrfs_extent_item *)(path.nodes[0]->leaf.data +
170 btrfs_item_offset(item));
171 BUG_ON(ei->refs == 0);
172 refs = btrfs_extent_refs(ei) - 1;
173 btrfs_set_extent_refs(ei, refs);
175 if (!root->ref_cows) {
177 radix_tree_preload(GFP_KERNEL);
178 err = radix_tree_insert(&extent_root->pinned_radix,
179 blocknr, (void *)blocknr);
181 radix_tree_preload_end();
183 ret = btrfs_del_item(extent_root, &path);
184 if (root != extent_root &&
185 extent_root->last_insert.objectid < blocknr)
186 extent_root->last_insert.objectid = blocknr;
190 btrfs_release_path(extent_root, &path);
191 finish_current_insert(extent_root);
196 * find all the blocks marked as pending in the radix tree and remove
197 * them from the extent map
199 static int del_pending_extents(struct btrfs_root *extent_root)
202 struct btrfs_buffer *gang[4];
206 ret = radix_tree_gang_lookup_tag(&extent_root->cache_radix,
209 CTREE_EXTENT_PENDING_DEL);
212 for (i = 0; i < ret; i++) {
213 ret = __free_extent(extent_root, gang[i]->blocknr, 1);
214 radix_tree_tag_clear(&extent_root->cache_radix,
216 CTREE_EXTENT_PENDING_DEL);
217 btrfs_block_release(extent_root, gang[i]);
223 static int run_pending(struct btrfs_root *extent_root)
225 while(radix_tree_tagged(&extent_root->cache_radix,
226 CTREE_EXTENT_PENDING_DEL))
227 del_pending_extents(extent_root);
233 * remove an extent from the root, returns 0 on success
235 int btrfs_free_extent(struct btrfs_root *root, u64 blocknr, u64 num_blocks)
237 struct btrfs_key key;
238 struct btrfs_root *extent_root = root->extent_root;
239 struct btrfs_buffer *t;
243 if (root == extent_root) {
244 t = find_tree_block(root, blocknr);
245 radix_tree_tag_set(&root->cache_radix, blocknr,
246 CTREE_EXTENT_PENDING_DEL);
249 key.objectid = blocknr;
251 key.offset = num_blocks;
252 ret = __free_extent(root, blocknr, num_blocks);
253 pending_ret = run_pending(root->extent_root);
254 return ret ? ret : pending_ret;
258 * walks the btree of allocated extents and find a hole of a given size.
259 * The key ins is changed to record the hole:
260 * ins->objectid == block start
262 * ins->offset == number of blocks
263 * Any available blocks before search_start are skipped.
265 static int find_free_extent(struct btrfs_root *orig_root, u64 num_blocks,
266 u64 search_start, u64 search_end,
267 struct btrfs_key *ins)
269 struct btrfs_path path;
270 struct btrfs_key key;
277 struct btrfs_leaf *l;
278 struct btrfs_root * root = orig_root->extent_root;
279 int total_needed = num_blocks;
281 total_needed += (btrfs_header_level(&root->node->node.header) + 1) * 3;
282 if (root->last_insert.objectid > search_start)
283 search_start = root->last_insert.objectid;
285 btrfs_init_path(&path);
286 ins->objectid = search_start;
290 ret = btrfs_search_slot(root, ins, &path, 0, 0);
294 if (path.slots[0] > 0)
298 l = &path.nodes[0]->leaf;
299 slot = path.slots[0];
300 if (slot >= btrfs_header_nritems(&l->header)) {
301 ret = btrfs_next_leaf(root, &path);
307 ins->objectid = search_start;
308 ins->offset = (u64)-1;
312 ins->objectid = last_block > search_start ?
313 last_block : search_start;
314 ins->offset = (u64)-1;
317 btrfs_disk_key_to_cpu(&key, &l->items[slot].key);
318 if (key.objectid >= search_start) {
320 if (last_block < search_start)
321 last_block = search_start;
322 hole_size = key.objectid - last_block;
323 if (hole_size > total_needed) {
324 ins->objectid = last_block;
325 ins->offset = hole_size;
331 last_block = key.objectid + key.offset;
336 /* we have to make sure we didn't find an extent that has already
337 * been allocated by the map tree or the original allocation
339 btrfs_release_path(root, &path);
340 BUG_ON(ins->objectid < search_start);
341 for (test_block = ins->objectid;
342 test_block < ins->objectid + total_needed; test_block++) {
343 if (radix_tree_lookup(&root->pinned_radix, test_block)) {
344 search_start = test_block + 1;
348 BUG_ON(root->current_insert.offset);
349 root->current_insert.offset = total_needed - num_blocks;
350 root->current_insert.objectid = ins->objectid + num_blocks;
351 root->current_insert.flags = 0;
352 root->last_insert.objectid = ins->objectid;
353 ins->offset = num_blocks;
356 btrfs_release_path(root, &path);
361 * finds a free extent and does all the dirty work required for allocation
362 * returns the key for the extent through ins, and a tree buffer for
363 * the first block of the extent through buf.
365 * returns 0 if everything worked, non-zero otherwise.
367 static int alloc_extent(struct btrfs_root *root, u64 num_blocks,
368 u64 search_start, u64 search_end, u64 owner,
369 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);
429 * helper function for drop_snapshot, this walks down the tree dropping ref
432 static int walk_down_tree(struct btrfs_root *root,
433 struct btrfs_path *path, int *level)
435 struct btrfs_buffer *next;
436 struct btrfs_buffer *cur;
441 ret = lookup_block_ref(root, path->nodes[*level]->blocknr, &refs);
446 * walk down to the last node level and free all the leaves
449 cur = path->nodes[*level];
450 if (path->slots[*level] >=
451 btrfs_header_nritems(&cur->node.header))
453 blocknr = btrfs_node_blockptr(&cur->node, path->slots[*level]);
454 ret = lookup_block_ref(root, blocknr, &refs);
455 if (refs != 1 || *level == 1) {
456 path->slots[*level]++;
457 ret = btrfs_free_extent(root, blocknr, 1);
462 next = read_tree_block(root, blocknr);
463 if (path->nodes[*level-1])
464 btrfs_block_release(root, path->nodes[*level-1]);
465 path->nodes[*level-1] = next;
466 *level = btrfs_header_level(&next->node.header);
467 path->slots[*level] = 0;
470 ret = btrfs_free_extent(root, path->nodes[*level]->blocknr, 1);
471 btrfs_block_release(root, path->nodes[*level]);
472 path->nodes[*level] = NULL;
479 * helper for dropping snapshots. This walks back up the tree in the path
480 * to find the first node higher up where we haven't yet gone through
483 static int walk_up_tree(struct btrfs_root *root, struct btrfs_path *path,
489 for(i = *level; i < BTRFS_MAX_LEVEL - 1 && path->nodes[i]; i++) {
490 slot = path->slots[i];
492 btrfs_header_nritems(&path->nodes[i]->node.header)- 1) {
497 ret = btrfs_free_extent(root,
498 path->nodes[*level]->blocknr, 1);
499 btrfs_block_release(root, path->nodes[*level]);
500 path->nodes[*level] = NULL;
509 * drop the reference count on the tree rooted at 'snap'. This traverses
510 * the tree freeing any blocks that have a ref count of zero after being
513 int btrfs_drop_snapshot(struct btrfs_root *root, struct btrfs_buffer *snap)
518 struct btrfs_path path;
522 btrfs_init_path(&path);
524 level = btrfs_header_level(&snap->node.header);
526 path.nodes[level] = snap;
527 path.slots[level] = 0;
529 wret = walk_down_tree(root, &path, &level);
535 wret = walk_up_tree(root, &path, &level);
541 for (i = 0; i <= orig_level; i++) {
543 btrfs_block_release(root, path.nodes[i]);