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,
11 struct btrfs_key *ins);
12 static int finish_current_insert(struct ctree_root *extent_root);
13 static int run_pending(struct ctree_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 ctree_root *root, u64 blocknr)
26 struct ctree_path path;
30 struct extent_item *item;
34 find_free_extent(root->extent_root, 0, 0, (u64)-1, &ins);
36 key.objectid = blocknr;
39 ret = search_slot(root->extent_root, &key, &path, 0, 1);
43 l = &path.nodes[0]->leaf;
44 item = (struct extent_item *)(l->data + btrfs_item_offset(l->items +
46 refs = btrfs_extent_refs(item);
47 btrfs_set_extent_refs(item, refs + 1);
49 BUG_ON(list_empty(&path.nodes[0]->dirty));
50 release_path(root->extent_root, &path);
51 finish_current_insert(root->extent_root);
52 run_pending(root->extent_root);
56 static int lookup_block_ref(struct ctree_root *root, u64 blocknr, u32 *refs)
58 struct ctree_path path;
62 struct extent_item *item;
64 key.objectid = blocknr;
67 ret = search_slot(root->extent_root, &key, &path, 0, 0);
70 l = &path.nodes[0]->leaf;
71 item = (struct extent_item *)(l->data +
72 btrfs_item_offset(l->items +
74 *refs = btrfs_extent_refs(item);
75 release_path(root->extent_root, &path);
79 int btrfs_inc_ref(struct ctree_root *root, struct tree_buffer *buf)
84 if (root == root->extent_root)
86 if (btrfs_is_leaf(&buf->node))
89 for (i = 0; i < btrfs_header_nritems(&buf->node.header); i++) {
90 blocknr = btrfs_node_blockptr(&buf->node, i);
91 inc_block_ref(root, blocknr);
96 int btrfs_finish_extent_commit(struct ctree_root *root)
98 struct ctree_root *extent_root = root->extent_root;
99 unsigned long gang[8];
104 ret = radix_tree_gang_lookup(&extent_root->pinned_radix,
109 for (i = 0; i < ret; i++) {
110 radix_tree_delete(&extent_root->pinned_radix, gang[i]);
113 extent_root->last_insert.objectid = 0;
114 extent_root->last_insert.offset = 0;
118 static int finish_current_insert(struct ctree_root *extent_root)
120 struct btrfs_key ins;
121 struct 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 = 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 int __free_extent(struct ctree_root *root, u64 blocknr, u64 num_blocks)
146 struct ctree_path path;
147 struct btrfs_key key;
148 struct ctree_root *extent_root = root->extent_root;
150 struct btrfs_item *item;
151 struct 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);
161 ret = search_slot(extent_root, &key, &path, -1, 1);
163 printf("failed to find %Lu\n", key.objectid);
164 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 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 == extent_root) {
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 = 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 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 ctree_root *extent_root)
202 struct tree_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 tree_block_release(extent_root, gang[i]);
223 static int run_pending(struct ctree_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 free_extent(struct ctree_root *root, u64 blocknr, u64 num_blocks)
237 struct btrfs_key key;
238 struct ctree_root *extent_root = root->extent_root;
239 struct tree_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 ctree_root *orig_root, u64 num_blocks,
266 u64 search_start, u64 search_end,
267 struct btrfs_key *ins)
269 struct ctree_path path;
270 struct btrfs_key key;
278 struct ctree_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;
286 ins->objectid = search_start;
290 ret = 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 = 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 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 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 int alloc_extent(struct ctree_root *root, u64 num_blocks, u64 search_start,
368 u64 search_end, u64 owner, struct btrfs_key *ins)
372 struct ctree_root *extent_root = root->extent_root;
373 struct extent_item extent_item;
375 btrfs_set_extent_refs(&extent_item, 1);
376 btrfs_set_extent_owner(&extent_item, owner);
378 if (root == extent_root) {
379 BUG_ON(extent_root->current_insert.offset == 0);
380 BUG_ON(num_blocks != 1);
381 BUG_ON(extent_root->current_insert.flags ==
382 extent_root->current_insert.offset);
384 ins->objectid = extent_root->current_insert.objectid +
385 extent_root->current_insert.flags++;
388 ret = find_free_extent(root, num_blocks, search_start,
393 ret = insert_item(extent_root, ins, &extent_item,
394 sizeof(extent_item));
396 finish_current_insert(extent_root);
397 pending_ret = run_pending(extent_root);
406 * helper function to allocate a block for a given tree
407 * returns the tree buffer or NULL.
409 struct tree_buffer *alloc_free_block(struct ctree_root *root)
411 struct btrfs_key ins;
413 struct tree_buffer *buf;
415 ret = alloc_extent(root, 1, 0, (unsigned long)-1,
416 btrfs_header_parentid(&root->node->node.header),
422 buf = find_tree_block(root, ins.objectid);
423 dirty_tree_block(root, buf);
427 int walk_down_tree(struct ctree_root *root, struct ctree_path *path, int *level)
429 struct tree_buffer *next;
430 struct tree_buffer *cur;
435 ret = lookup_block_ref(root, path->nodes[*level]->blocknr, &refs);
440 cur = path->nodes[*level];
441 if (path->slots[*level] >=
442 btrfs_header_nritems(&cur->node.header))
444 blocknr = btrfs_node_blockptr(&cur->node, path->slots[*level]);
445 ret = lookup_block_ref(root, blocknr, &refs);
446 if (refs != 1 || *level == 1) {
447 path->slots[*level]++;
448 ret = free_extent(root, blocknr, 1);
453 next = read_tree_block(root, blocknr);
454 if (path->nodes[*level-1])
455 tree_block_release(root, path->nodes[*level-1]);
456 path->nodes[*level-1] = next;
457 *level = btrfs_header_level(&next->node.header);
458 path->slots[*level] = 0;
461 ret = free_extent(root, path->nodes[*level]->blocknr, 1);
462 tree_block_release(root, path->nodes[*level]);
463 path->nodes[*level] = NULL;
469 int walk_up_tree(struct ctree_root *root, struct ctree_path *path, int *level)
474 for(i = *level; i < MAX_LEVEL - 1 && path->nodes[i]; i++) {
475 slot = path->slots[i];
477 btrfs_header_nritems(&path->nodes[i]->node.header)- 1) {
482 ret = free_extent(root,
483 path->nodes[*level]->blocknr, 1);
484 tree_block_release(root, path->nodes[*level]);
485 path->nodes[*level] = NULL;
493 int btrfs_drop_snapshot(struct ctree_root *root, struct tree_buffer *snap)
497 struct ctree_path path;
503 level = btrfs_header_level(&snap->node.header);
505 path.nodes[level] = snap;
506 path.slots[level] = 0;
508 ret = walk_down_tree(root, &path, &level);
511 ret = walk_up_tree(root, &path, &level);
515 for (i = 0; i <= orig_level; i++) {
517 tree_block_release(root, path.nodes[i]);