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 = btrfs_item_ptr(l, path.slots[0], struct btrfs_extent_item);
45 refs = btrfs_extent_refs(item);
46 btrfs_set_extent_refs(item, refs + 1);
48 BUG_ON(list_empty(&path.nodes[0]->dirty));
49 btrfs_release_path(root->extent_root, &path);
50 finish_current_insert(root->extent_root);
51 run_pending(root->extent_root);
55 static int lookup_block_ref(struct btrfs_root *root, u64 blocknr, u32 *refs)
57 struct btrfs_path path;
61 struct btrfs_extent_item *item;
62 btrfs_init_path(&path);
63 key.objectid = blocknr;
66 ret = btrfs_search_slot(root->extent_root, &key, &path, 0, 0);
69 l = &path.nodes[0]->leaf;
70 item = btrfs_item_ptr(l, path.slots[0], struct btrfs_extent_item);
71 *refs = btrfs_extent_refs(item);
72 btrfs_release_path(root->extent_root, &path);
76 int btrfs_inc_ref(struct btrfs_root *root, struct btrfs_buffer *buf)
83 if (btrfs_is_leaf(&buf->node))
86 for (i = 0; i < btrfs_header_nritems(&buf->node.header); i++) {
87 blocknr = btrfs_node_blockptr(&buf->node, i);
88 inc_block_ref(root, blocknr);
93 int btrfs_finish_extent_commit(struct btrfs_root *root)
95 unsigned long gang[8];
100 ret = radix_tree_gang_lookup(&root->pinned_radix,
105 for (i = 0; i < ret; i++) {
106 radix_tree_delete(&root->pinned_radix, gang[i]);
109 root->last_insert.objectid = 0;
110 root->last_insert.offset = 0;
114 static int finish_current_insert(struct btrfs_root *extent_root)
116 struct btrfs_key ins;
117 struct btrfs_extent_item extent_item;
121 btrfs_set_extent_refs(&extent_item, 1);
122 btrfs_set_extent_owner(&extent_item,
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 = btrfs_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 static int __free_extent(struct btrfs_root *root, u64 blocknr, u64 num_blocks)
142 struct btrfs_path path;
143 struct btrfs_key key;
144 struct btrfs_root *extent_root = root->extent_root;
146 struct btrfs_extent_item *ei;
147 struct btrfs_key ins;
150 key.objectid = blocknr;
152 key.offset = num_blocks;
154 find_free_extent(root, 0, 0, (u64)-1, &ins);
155 btrfs_init_path(&path);
156 ret = btrfs_search_slot(extent_root, &key, &path, -1, 1);
158 printf("failed to find %Lu\n", key.objectid);
159 btrfs_print_tree(extent_root, extent_root->node);
160 printf("failed to find %Lu\n", key.objectid);
163 ei = btrfs_item_ptr(&path.nodes[0]->leaf, path.slots[0],
164 struct btrfs_extent_item);
165 BUG_ON(ei->refs == 0);
166 refs = btrfs_extent_refs(ei) - 1;
167 btrfs_set_extent_refs(ei, refs);
169 if (!root->ref_cows) {
171 radix_tree_preload(GFP_KERNEL);
172 err = radix_tree_insert(&extent_root->pinned_radix,
173 blocknr, (void *)blocknr);
175 radix_tree_preload_end();
177 ret = btrfs_del_item(extent_root, &path);
178 if (root != extent_root &&
179 extent_root->last_insert.objectid > blocknr)
180 extent_root->last_insert.objectid = blocknr;
184 btrfs_release_path(extent_root, &path);
185 finish_current_insert(extent_root);
190 * find all the blocks marked as pending in the radix tree and remove
191 * them from the extent map
193 static int del_pending_extents(struct btrfs_root *extent_root)
196 struct btrfs_buffer *gang[4];
200 ret = radix_tree_gang_lookup_tag(&extent_root->cache_radix,
203 CTREE_EXTENT_PENDING_DEL);
206 for (i = 0; i < ret; i++) {
207 ret = __free_extent(extent_root, gang[i]->blocknr, 1);
208 radix_tree_tag_clear(&extent_root->cache_radix,
210 CTREE_EXTENT_PENDING_DEL);
211 btrfs_block_release(extent_root, gang[i]);
217 static int run_pending(struct btrfs_root *extent_root)
219 while(radix_tree_tagged(&extent_root->cache_radix,
220 CTREE_EXTENT_PENDING_DEL))
221 del_pending_extents(extent_root);
227 * remove an extent from the root, returns 0 on success
229 int btrfs_free_extent(struct btrfs_root *root, u64 blocknr, u64 num_blocks)
231 struct btrfs_key key;
232 struct btrfs_root *extent_root = root->extent_root;
233 struct btrfs_buffer *t;
237 if (root == extent_root) {
238 t = find_tree_block(root, blocknr);
239 radix_tree_tag_set(&root->cache_radix, blocknr,
240 CTREE_EXTENT_PENDING_DEL);
243 key.objectid = blocknr;
245 key.offset = num_blocks;
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
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;
279 btrfs_init_path(&path);
280 ins->objectid = search_start;
284 ret = btrfs_search_slot(root, ins, &path, 0, 0);
288 if (path.slots[0] > 0)
292 l = &path.nodes[0]->leaf;
293 slot = path.slots[0];
294 if (slot >= btrfs_header_nritems(&l->header)) {
295 ret = btrfs_next_leaf(root, &path);
301 ins->objectid = search_start;
302 ins->offset = (u64)-1;
306 ins->objectid = last_block > search_start ?
307 last_block : search_start;
308 ins->offset = (u64)-1;
311 btrfs_disk_key_to_cpu(&key, &l->items[slot].key);
312 if (key.objectid >= search_start) {
314 if (last_block < search_start)
315 last_block = search_start;
316 hole_size = key.objectid - last_block;
317 if (hole_size > total_needed) {
318 ins->objectid = last_block;
319 ins->offset = hole_size;
325 last_block = key.objectid + key.offset;
330 /* we have to make sure we didn't find an extent that has already
331 * been allocated by the map tree or the original allocation
333 btrfs_release_path(root, &path);
334 BUG_ON(ins->objectid < search_start);
335 for (test_block = ins->objectid;
336 test_block < ins->objectid + total_needed; test_block++) {
337 if (radix_tree_lookup(&root->pinned_radix, test_block)) {
338 search_start = test_block + 1;
342 BUG_ON(root->current_insert.offset);
343 root->current_insert.offset = total_needed - num_blocks;
344 root->current_insert.objectid = ins->objectid + num_blocks;
345 root->current_insert.flags = 0;
346 root->last_insert.objectid = ins->objectid;
347 ins->offset = num_blocks;
350 btrfs_release_path(root, &path);
355 * finds a free extent and does all the dirty work required for allocation
356 * returns the key for the extent through ins, and a tree buffer for
357 * the first block of the extent through buf.
359 * returns 0 if everything worked, non-zero otherwise.
361 static int alloc_extent(struct btrfs_root *root, u64 num_blocks,
362 u64 search_start, u64 search_end, u64 owner,
363 struct btrfs_key *ins)
367 struct btrfs_root *extent_root = root->extent_root;
368 struct btrfs_extent_item extent_item;
370 btrfs_set_extent_refs(&extent_item, 1);
371 btrfs_set_extent_owner(&extent_item, owner);
373 if (root == extent_root) {
374 BUG_ON(extent_root->current_insert.offset == 0);
375 BUG_ON(num_blocks != 1);
376 BUG_ON(extent_root->current_insert.flags ==
377 extent_root->current_insert.offset);
379 ins->objectid = extent_root->current_insert.objectid +
380 extent_root->current_insert.flags++;
383 ret = find_free_extent(root, num_blocks, search_start,
388 ret = btrfs_insert_item(extent_root, ins, &extent_item,
389 sizeof(extent_item));
391 finish_current_insert(extent_root);
392 pending_ret = run_pending(extent_root);
401 * helper function to allocate a block for a given tree
402 * returns the tree buffer or NULL.
404 struct btrfs_buffer *btrfs_alloc_free_block(struct btrfs_root *root)
406 struct btrfs_key ins;
408 struct btrfs_buffer *buf;
410 ret = alloc_extent(root, 1, 0, (unsigned long)-1,
411 btrfs_header_parentid(&root->node->node.header),
417 buf = find_tree_block(root, ins.objectid);
418 dirty_tree_block(root, buf);
423 * helper function for drop_snapshot, this walks down the tree dropping ref
426 static int walk_down_tree(struct btrfs_root *root,
427 struct btrfs_path *path, int *level)
429 struct btrfs_buffer *next;
430 struct btrfs_buffer *cur;
435 ret = lookup_block_ref(root, path->nodes[*level]->blocknr, &refs);
440 * walk down to the last node level and free all the leaves
443 cur = path->nodes[*level];
444 if (path->slots[*level] >=
445 btrfs_header_nritems(&cur->node.header))
447 blocknr = btrfs_node_blockptr(&cur->node, path->slots[*level]);
448 ret = lookup_block_ref(root, blocknr, &refs);
449 if (refs != 1 || *level == 1) {
450 path->slots[*level]++;
451 ret = btrfs_free_extent(root, blocknr, 1);
456 next = read_tree_block(root, blocknr);
457 if (path->nodes[*level-1])
458 btrfs_block_release(root, path->nodes[*level-1]);
459 path->nodes[*level-1] = next;
460 *level = btrfs_header_level(&next->node.header);
461 path->slots[*level] = 0;
464 ret = btrfs_free_extent(root, path->nodes[*level]->blocknr, 1);
465 btrfs_block_release(root, path->nodes[*level]);
466 path->nodes[*level] = NULL;
473 * helper for dropping snapshots. This walks back up the tree in the path
474 * to find the first node higher up where we haven't yet gone through
477 static int walk_up_tree(struct btrfs_root *root, struct btrfs_path *path,
483 for(i = *level; i < BTRFS_MAX_LEVEL - 1 && path->nodes[i]; i++) {
484 slot = path->slots[i];
486 btrfs_header_nritems(&path->nodes[i]->node.header)- 1) {
491 ret = btrfs_free_extent(root,
492 path->nodes[*level]->blocknr, 1);
493 btrfs_block_release(root, path->nodes[*level]);
494 path->nodes[*level] = NULL;
503 * drop the reference count on the tree rooted at 'snap'. This traverses
504 * the tree freeing any blocks that have a ref count of zero after being
507 int btrfs_drop_snapshot(struct btrfs_root *root, struct btrfs_buffer *snap)
512 struct btrfs_path path;
516 btrfs_init_path(&path);
518 level = btrfs_header_level(&snap->node.header);
520 path.nodes[level] = snap;
521 path.slots[level] = 0;
523 wret = walk_down_tree(root, &path, &level);
529 wret = walk_up_tree(root, &path, &level);
535 for (i = 0; i <= orig_level; i++) {
537 btrfs_block_release(root, path.nodes[i]);