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;
38 btrfs_set_key_type(&key, BTRFS_EXTENT_ITEM_KEY);
40 ret = btrfs_search_slot(root->extent_root, &key, &path, 0, 1);
44 l = &path.nodes[0]->leaf;
45 item = btrfs_item_ptr(l, path.slots[0], struct btrfs_extent_item);
46 refs = btrfs_extent_refs(item);
47 btrfs_set_extent_refs(item, refs + 1);
49 BUG_ON(list_empty(&path.nodes[0]->dirty));
50 btrfs_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 btrfs_root *root, u64 blocknr, u32 *refs)
58 struct btrfs_path path;
62 struct btrfs_extent_item *item;
63 btrfs_init_path(&path);
64 key.objectid = blocknr;
67 btrfs_set_key_type(&key, BTRFS_EXTENT_ITEM_KEY);
68 ret = btrfs_search_slot(root->extent_root, &key, &path, 0, 0);
71 l = &path.nodes[0]->leaf;
72 item = btrfs_item_ptr(l, path.slots[0], struct btrfs_extent_item);
73 *refs = btrfs_extent_refs(item);
74 btrfs_release_path(root->extent_root, &path);
78 int btrfs_inc_ref(struct btrfs_root *root, struct btrfs_buffer *buf)
85 if (btrfs_is_leaf(&buf->node))
88 for (i = 0; i < btrfs_header_nritems(&buf->node.header); i++) {
89 blocknr = btrfs_node_blockptr(&buf->node, i);
90 inc_block_ref(root, blocknr);
95 int btrfs_finish_extent_commit(struct btrfs_root *root)
97 unsigned long gang[8];
102 ret = radix_tree_gang_lookup(&root->pinned_radix,
107 for (i = 0; i < ret; i++) {
108 radix_tree_delete(&root->pinned_radix, gang[i]);
111 root->last_insert.objectid = 0;
112 root->last_insert.offset = 0;
116 static int finish_current_insert(struct btrfs_root *extent_root)
118 struct btrfs_key ins;
119 struct btrfs_extent_item extent_item;
123 btrfs_set_extent_refs(&extent_item, 1);
124 btrfs_set_extent_owner(&extent_item,
125 btrfs_header_parentid(&extent_root->node->node.header));
128 btrfs_set_key_type(&ins, BTRFS_EXTENT_ITEM_KEY);
130 for (i = 0; i < extent_root->current_insert.flags; i++) {
131 ins.objectid = extent_root->current_insert.objectid + i;
132 ret = btrfs_insert_item(extent_root, &ins, &extent_item,
133 sizeof(extent_item));
136 extent_root->current_insert.offset = 0;
141 * remove an extent from the root, returns 0 on success
143 static int __free_extent(struct btrfs_root *root, u64 blocknr, u64 num_blocks)
145 struct btrfs_path path;
146 struct btrfs_key key;
147 struct btrfs_root *extent_root = root->extent_root;
149 struct btrfs_extent_item *ei;
150 struct btrfs_key ins;
153 key.objectid = blocknr;
155 btrfs_set_key_type(&key, BTRFS_EXTENT_ITEM_KEY);
156 key.offset = num_blocks;
158 find_free_extent(root, 0, 0, (u64)-1, &ins);
159 btrfs_init_path(&path);
160 ret = btrfs_search_slot(extent_root, &key, &path, -1, 1);
162 printf("failed to find %Lu\n", key.objectid);
163 btrfs_print_tree(extent_root, extent_root->node);
164 printf("failed to find %Lu\n", key.objectid);
167 ei = btrfs_item_ptr(&path.nodes[0]->leaf, path.slots[0],
168 struct btrfs_extent_item);
169 BUG_ON(ei->refs == 0);
170 refs = btrfs_extent_refs(ei) - 1;
171 btrfs_set_extent_refs(ei, refs);
173 if (!root->ref_cows) {
175 radix_tree_preload(GFP_KERNEL);
176 err = radix_tree_insert(&extent_root->pinned_radix,
177 blocknr, (void *)blocknr);
179 radix_tree_preload_end();
181 ret = btrfs_del_item(extent_root, &path);
182 if (root != extent_root &&
183 extent_root->last_insert.objectid > blocknr)
184 extent_root->last_insert.objectid = blocknr;
188 btrfs_release_path(extent_root, &path);
189 finish_current_insert(extent_root);
194 * find all the blocks marked as pending in the radix tree and remove
195 * them from the extent map
197 static int del_pending_extents(struct btrfs_root *extent_root)
200 struct btrfs_buffer *gang[4];
204 ret = radix_tree_gang_lookup_tag(&extent_root->cache_radix,
207 CTREE_EXTENT_PENDING_DEL);
210 for (i = 0; i < ret; i++) {
211 ret = __free_extent(extent_root, gang[i]->blocknr, 1);
212 radix_tree_tag_clear(&extent_root->cache_radix,
214 CTREE_EXTENT_PENDING_DEL);
215 btrfs_block_release(extent_root, gang[i]);
221 static int run_pending(struct btrfs_root *extent_root)
223 while(radix_tree_tagged(&extent_root->cache_radix,
224 CTREE_EXTENT_PENDING_DEL))
225 del_pending_extents(extent_root);
231 * remove an extent from the root, returns 0 on success
233 int btrfs_free_extent(struct btrfs_root *root, u64 blocknr, u64 num_blocks)
235 struct btrfs_root *extent_root = root->extent_root;
236 struct btrfs_buffer *t;
240 if (root == extent_root) {
241 t = find_tree_block(root, blocknr);
242 radix_tree_tag_set(&root->cache_radix, blocknr,
243 CTREE_EXTENT_PENDING_DEL);
246 ret = __free_extent(root, blocknr, num_blocks);
247 pending_ret = run_pending(root->extent_root);
248 return ret ? ret : pending_ret;
252 * walks the btree of allocated extents and find a hole of a given size.
253 * The key ins is changed to record the hole:
254 * ins->objectid == block start
255 * ins->flags = BTRFS_EXTENT_ITEM_KEY
256 * ins->offset == number of blocks
257 * Any available blocks before search_start are skipped.
259 static int find_free_extent(struct btrfs_root *orig_root, u64 num_blocks,
260 u64 search_start, u64 search_end,
261 struct btrfs_key *ins)
263 struct btrfs_path path;
264 struct btrfs_key key;
271 struct btrfs_leaf *l;
272 struct btrfs_root * root = orig_root->extent_root;
273 int total_needed = num_blocks;
275 total_needed += (btrfs_header_level(&root->node->node.header) + 1) * 3;
276 if (root->last_insert.objectid > search_start)
277 search_start = root->last_insert.objectid;
280 btrfs_set_key_type(ins, BTRFS_EXTENT_ITEM_KEY);
283 btrfs_init_path(&path);
284 ins->objectid = search_start;
287 ret = btrfs_search_slot(root, ins, &path, 0, 0);
291 if (path.slots[0] > 0)
295 l = &path.nodes[0]->leaf;
296 slot = path.slots[0];
297 if (slot >= btrfs_header_nritems(&l->header)) {
298 ret = btrfs_next_leaf(root, &path);
304 ins->objectid = search_start;
305 ins->offset = (u64)-1;
309 ins->objectid = last_block > search_start ?
310 last_block : search_start;
311 ins->offset = (u64)-1;
314 btrfs_disk_key_to_cpu(&key, &l->items[slot].key);
315 if (key.objectid >= search_start) {
317 if (last_block < search_start)
318 last_block = search_start;
319 hole_size = key.objectid - last_block;
320 if (hole_size > total_needed) {
321 ins->objectid = last_block;
322 ins->offset = hole_size;
328 last_block = key.objectid + key.offset;
333 /* we have to make sure we didn't find an extent that has already
334 * been allocated by the map tree or the original allocation
336 btrfs_release_path(root, &path);
337 BUG_ON(ins->objectid < search_start);
338 for (test_block = ins->objectid;
339 test_block < ins->objectid + total_needed; test_block++) {
340 if (radix_tree_lookup(&root->pinned_radix, test_block)) {
341 search_start = test_block + 1;
345 BUG_ON(root->current_insert.offset);
346 root->current_insert.offset = total_needed - num_blocks;
347 root->current_insert.objectid = ins->objectid + num_blocks;
348 root->current_insert.flags = 0;
349 root->last_insert.objectid = ins->objectid;
350 ins->offset = num_blocks;
353 btrfs_release_path(root, &path);
358 * finds a free extent and does all the dirty work required for allocation
359 * returns the key for the extent through ins, and a tree buffer for
360 * the first block of the extent through buf.
362 * returns 0 if everything worked, non-zero otherwise.
364 static int alloc_extent(struct btrfs_root *root, u64 num_blocks,
365 u64 search_start, u64 search_end, u64 owner,
366 struct btrfs_key *ins)
370 struct btrfs_root *extent_root = root->extent_root;
371 struct btrfs_extent_item extent_item;
373 btrfs_set_extent_refs(&extent_item, 1);
374 btrfs_set_extent_owner(&extent_item, owner);
376 if (root == extent_root) {
377 BUG_ON(extent_root->current_insert.offset == 0);
378 BUG_ON(num_blocks != 1);
379 BUG_ON(extent_root->current_insert.flags ==
380 extent_root->current_insert.offset);
382 ins->objectid = extent_root->current_insert.objectid +
383 extent_root->current_insert.flags++;
386 ret = find_free_extent(root, num_blocks, search_start,
391 ret = btrfs_insert_item(extent_root, ins, &extent_item,
392 sizeof(extent_item));
394 finish_current_insert(extent_root);
395 pending_ret = run_pending(extent_root);
404 * helper function to allocate a block for a given tree
405 * returns the tree buffer or NULL.
407 struct btrfs_buffer *btrfs_alloc_free_block(struct btrfs_root *root)
409 struct btrfs_key ins;
411 struct btrfs_buffer *buf;
413 ret = alloc_extent(root, 1, 0, (unsigned long)-1,
414 btrfs_header_parentid(&root->node->node.header),
420 buf = find_tree_block(root, ins.objectid);
421 dirty_tree_block(root, buf);
426 * helper function for drop_snapshot, this walks down the tree dropping ref
429 static int walk_down_tree(struct btrfs_root *root,
430 struct btrfs_path *path, int *level)
432 struct btrfs_buffer *next;
433 struct btrfs_buffer *cur;
438 ret = lookup_block_ref(root, path->nodes[*level]->blocknr, &refs);
443 * walk down to the last node level and free all the leaves
446 cur = path->nodes[*level];
447 if (path->slots[*level] >=
448 btrfs_header_nritems(&cur->node.header))
450 blocknr = btrfs_node_blockptr(&cur->node, path->slots[*level]);
451 ret = lookup_block_ref(root, blocknr, &refs);
452 if (refs != 1 || *level == 1) {
453 path->slots[*level]++;
454 ret = btrfs_free_extent(root, blocknr, 1);
459 next = read_tree_block(root, blocknr);
460 if (path->nodes[*level-1])
461 btrfs_block_release(root, path->nodes[*level-1]);
462 path->nodes[*level-1] = next;
463 *level = btrfs_header_level(&next->node.header);
464 path->slots[*level] = 0;
467 ret = btrfs_free_extent(root, path->nodes[*level]->blocknr, 1);
468 btrfs_block_release(root, path->nodes[*level]);
469 path->nodes[*level] = NULL;
476 * helper for dropping snapshots. This walks back up the tree in the path
477 * to find the first node higher up where we haven't yet gone through
480 static int walk_up_tree(struct btrfs_root *root, struct btrfs_path *path,
486 for(i = *level; i < BTRFS_MAX_LEVEL - 1 && path->nodes[i]; i++) {
487 slot = path->slots[i];
489 btrfs_header_nritems(&path->nodes[i]->node.header)- 1) {
494 ret = btrfs_free_extent(root,
495 path->nodes[*level]->blocknr, 1);
496 btrfs_block_release(root, path->nodes[*level]);
497 path->nodes[*level] = NULL;
506 * drop the reference count on the tree rooted at 'snap'. This traverses
507 * the tree freeing any blocks that have a ref count of zero after being
510 int btrfs_drop_snapshot(struct btrfs_root *root, struct btrfs_buffer *snap)
515 struct btrfs_path path;
519 btrfs_init_path(&path);
521 level = btrfs_header_level(&snap->node.header);
523 path.nodes[level] = snap;
524 path.slots[level] = 0;
526 wret = walk_down_tree(root, &path, &level);
532 wret = walk_up_tree(root, &path, &level);
538 for (i = 0; i <= orig_level; i++) {
540 btrfs_block_release(root, path.nodes[i]);