diff options
Diffstat (limited to 'fs/btrfs/extent-tree.c')
| -rw-r--r-- | fs/btrfs/extent-tree.c | 5986 |
1 files changed, 5986 insertions, 0 deletions
diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c new file mode 100644 index 00000000000..293da650873 --- /dev/null +++ b/fs/btrfs/extent-tree.c @@ -0,0 +1,5986 @@ +/* + * Copyright (C) 2007 Oracle. All rights reserved. + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public + * License v2 as published by the Free Software Foundation. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + * General Public License for more details. + * + * You should have received a copy of the GNU General Public + * License along with this program; if not, write to the + * Free Software Foundation, Inc., 59 Temple Place - Suite 330, + * Boston, MA 021110-1307, USA. + */ +#include <linux/sched.h> +#include <linux/pagemap.h> +#include <linux/writeback.h> +#include <linux/blkdev.h> +#include <linux/version.h> +#include "compat.h" +#include "hash.h" +#include "crc32c.h" +#include "ctree.h" +#include "disk-io.h" +#include "print-tree.h" +#include "transaction.h" +#include "volumes.h" +#include "locking.h" +#include "ref-cache.h" +#include "compat.h" + +#define PENDING_EXTENT_INSERT 0 +#define PENDING_EXTENT_DELETE 1 +#define PENDING_BACKREF_UPDATE 2 + +struct pending_extent_op { + int type; + u64 bytenr; + u64 num_bytes; + u64 parent; + u64 orig_parent; + u64 generation; + u64 orig_generation; + int level; + struct list_head list; + int del; +}; + +static int finish_current_insert(struct btrfs_trans_handle *trans, + struct btrfs_root *extent_root, int all); +static int del_pending_extents(struct btrfs_trans_handle *trans, + struct btrfs_root *extent_root, int all); +static int pin_down_bytes(struct btrfs_trans_handle *trans, + struct btrfs_root *root, + u64 bytenr, u64 num_bytes, int is_data); +static int update_block_group(struct btrfs_trans_handle *trans, + struct btrfs_root *root, + u64 bytenr, u64 num_bytes, int alloc, + int mark_free); + +static int block_group_bits(struct btrfs_block_group_cache *cache, u64 bits) +{ + return (cache->flags & bits) == bits; +} + +/* + * this adds the block group to the fs_info rb tree for the block group + * cache + */ +static int btrfs_add_block_group_cache(struct btrfs_fs_info *info, + struct btrfs_block_group_cache *block_group) +{ + struct rb_node **p; + struct rb_node *parent = NULL; + struct btrfs_block_group_cache *cache; + + spin_lock(&info->block_group_cache_lock); + p = &info->block_group_cache_tree.rb_node; + + while (*p) { + parent = *p; + cache = rb_entry(parent, struct btrfs_block_group_cache, + cache_node); + if (block_group->key.objectid < cache->key.objectid) { + p = &(*p)->rb_left; + } else if (block_group->key.objectid > cache->key.objectid) { + p = &(*p)->rb_right; + } else { + spin_unlock(&info->block_group_cache_lock); + return -EEXIST; + } + } + + rb_link_node(&block_group->cache_node, parent, p); + rb_insert_color(&block_group->cache_node, + &info->block_group_cache_tree); + spin_unlock(&info->block_group_cache_lock); + + return 0; +} + +/* + * This will return the block group at or after bytenr if contains is 0, else + * it will return the block group that contains the bytenr + */ +static struct btrfs_block_group_cache * +block_group_cache_tree_search(struct btrfs_fs_info *info, u64 bytenr, + int contains) +{ + struct btrfs_block_group_cache *cache, *ret = NULL; + struct rb_node *n; + u64 end, start; + + spin_lock(&info->block_group_cache_lock); + n = info->block_group_cache_tree.rb_node; + + while (n) { + cache = rb_entry(n, struct btrfs_block_group_cache, + cache_node); + end = cache->key.objectid + cache->key.offset - 1; + start = cache->key.objectid; + + if (bytenr < start) { + if (!contains && (!ret || start < ret->key.objectid)) + ret = cache; + n = n->rb_left; + } else if (bytenr > start) { + if (contains && bytenr <= end) { + ret = cache; + break; + } + n = n->rb_right; + } else { + ret = cache; + break; + } + } + if (ret) + atomic_inc(&ret->count); + spin_unlock(&info->block_group_cache_lock); + + return ret; +} + +/* + * this is only called by cache_block_group, since we could have freed extents + * we need to check the pinned_extents for any extents that can't be used yet + * since their free space will be released as soon as the transaction commits. + */ +static int add_new_free_space(struct btrfs_block_group_cache *block_group, + struct btrfs_fs_info *info, u64 start, u64 end) +{ + u64 extent_start, extent_end, size; + int ret; + + mutex_lock(&info->pinned_mutex); + while (start < end) { + ret = find_first_extent_bit(&info->pinned_extents, start, + &extent_start, &extent_end, + EXTENT_DIRTY); + if (ret) + break; + + if (extent_start == start) { + start = extent_end + 1; + } else if (extent_start > start && extent_start < end) { + size = extent_start - start; + ret = btrfs_add_free_space(block_group, start, + size); + BUG_ON(ret); + start = extent_end + 1; + } else { + break; + } + } + + if (start < end) { + size = end - start; + ret = btrfs_add_free_space(block_group, start, size); + BUG_ON(ret); + } + mutex_unlock(&info->pinned_mutex); + + return 0; +} + +static int remove_sb_from_cache(struct btrfs_root *root, + struct btrfs_block_group_cache *cache) +{ + u64 bytenr; + u64 *logical; + int stripe_len; + int i, nr, ret; + + for (i = 0; i < BTRFS_SUPER_MIRROR_MAX; i++) { + bytenr = btrfs_sb_offset(i); + ret = btrfs_rmap_block(&root->fs_info->mapping_tree, + cache->key.objectid, bytenr, 0, + &logical, &nr, &stripe_len); + BUG_ON(ret); + while (nr--) { + btrfs_remove_free_space(cache, logical[nr], + stripe_len); + } + kfree(logical); + } + return 0; +} + +static int cache_block_group(struct btrfs_root *root, + struct btrfs_block_group_cache *block_group) +{ + struct btrfs_path *path; + int ret = 0; + struct btrfs_key key; + struct extent_buffer *leaf; + int slot; + u64 last; + + if (!block_group) + return 0; + + root = root->fs_info->extent_root; + + if (block_group->cached) + return 0; + + path = btrfs_alloc_path(); + if (!path) + return -ENOMEM; + + path->reada = 2; + /* + * we get into deadlocks with paths held by callers of this function. + * since the alloc_mutex is protecting things right now, just + * skip the locking here + */ + path->skip_locking = 1; + last = max_t(u64, block_group->key.objectid, BTRFS_SUPER_INFO_OFFSET); + key.objectid = last; + key.offset = 0; + btrfs_set_key_type(&key, BTRFS_EXTENT_ITEM_KEY); + ret = btrfs_search_slot(NULL, root, &key, path, 0, 0); + if (ret < 0) + goto err; + + while (1) { + leaf = path->nodes[0]; + slot = path->slots[0]; + if (slot >= btrfs_header_nritems(leaf)) { + ret = btrfs_next_leaf(root, path); + if (ret < 0) + goto err; + if (ret == 0) + continue; + else + break; + } + btrfs_item_key_to_cpu(leaf, &key, slot); + if (key.objectid < block_group->key.objectid) + goto next; + + if (key.objectid >= block_group->key.objectid + + block_group->key.offset) + break; + + if (btrfs_key_type(&key) == BTRFS_EXTENT_ITEM_KEY) { + add_new_free_space(block_group, root->fs_info, last, + key.objectid); + + last = key.objectid + key.offset; + } +next: + path->slots[0]++; + } + + add_new_free_space(block_group, root->fs_info, last, + block_group->key.objectid + + block_group->key.offset); + + remove_sb_from_cache(root, block_group); + block_group->cached = 1; + ret = 0; +err: + btrfs_free_path(path); + return ret; +} + +/* + * return the block group that starts at or after bytenr + */ +static struct btrfs_block_group_cache * +btrfs_lookup_first_block_group(struct btrfs_fs_info *info, u64 bytenr) +{ + struct btrfs_block_group_cache *cache; + + cache = block_group_cache_tree_search(info, bytenr, 0); + + return cache; +} + +/* + * return the block group that contains teh given bytenr + */ +struct btrfs_block_group_cache *btrfs_lookup_block_group( + struct btrfs_fs_info *info, + u64 bytenr) +{ + struct btrfs_block_group_cache *cache; + + cache = block_group_cache_tree_search(info, bytenr, 1); + + return cache; +} + +static inline void put_block_group(struct btrfs_block_group_cache *cache) +{ + if (atomic_dec_and_test(&cache->count)) + kfree(cache); +} + +static struct btrfs_space_info *__find_space_info(struct btrfs_fs_info *info, + u64 flags) +{ + struct list_head *head = &info->space_info; + struct list_head *cur; + struct btrfs_space_info *found; + list_for_each(cur, head) { + found = list_entry(cur, struct btrfs_space_info, list); + if (found->flags == flags) + return found; + } + return NULL; +} + +static u64 div_factor(u64 num, int factor) +{ + if (factor == 10) + return num; + num *= factor; + do_div(num, 10); + return num; +} + +u64 btrfs_find_block_group(struct btrfs_root *root, + u64 search_start, u64 search_hint, int owner) +{ + struct btrfs_block_group_cache *cache; + u64 used; + u64 last = max(search_hint, search_start); + u64 group_start = 0; + int full_search = 0; + int factor = 9; + int wrapped = 0; +again: + while (1) { + cache = btrfs_lookup_first_block_group(root->fs_info, last); + if (!cache) + break; + + spin_lock(&cache->lock); + last = cache->key.objectid + cache->key.offset; + used = btrfs_block_group_used(&cache->item); + + if ((full_search || !cache->ro) && + block_group_bits(cache, BTRFS_BLOCK_GROUP_METADATA)) { + if (used + cache->pinned + cache->reserved < + div_factor(cache->key.offset, factor)) { + group_start = cache->key.objectid; + spin_unlock(&cache->lock); + put_block_group(cache); + goto found; + } + } + spin_unlock(&cache->lock); + put_block_group(cache); + cond_resched(); + } + if (!wrapped) { + last = search_start; + wrapped = 1; + goto again; + } + if (!full_search && factor < 10) { + last = search_start; + full_search = 1; + factor = 10; + goto again; + } +found: + return group_start; +} + +/* simple helper to search for an existing extent at a given offset */ +int btrfs_lookup_extent(struct btrfs_root *root, u64 start, u64 len) +{ + int ret; + struct btrfs_key key; + struct btrfs_path *path; + + path = btrfs_alloc_path(); + BUG_ON(!path); + key.objectid = start; + key.offset = len; + btrfs_set_key_type(&key, BTRFS_EXTENT_ITEM_KEY); + ret = btrfs_search_slot(NULL, root->fs_info->extent_root, &key, path, + 0, 0); + btrfs_free_path(path); + return ret; +} + +/* + * Back reference rules. Back refs have three main goals: + * + * 1) differentiate between all holders of references to an extent so that + * when a reference is dropped we can make sure it was a valid reference + * before freeing the extent. + * + * 2) Provide enough information to quickly find the holders of an extent + * if we notice a given block is corrupted or bad. + * + * 3) Make it easy to migrate blocks for FS shrinking or storage pool + * maintenance. This is actually the same as #2, but with a slightly + * different use case. + * + * File extents can be referenced by: + * + * - multiple snapshots, subvolumes, or different generations in one subvol + * - different files inside a single subvolume + * - different offsets inside a file (bookend extents in file.c) + * + * The extent ref structure has fields for: + * + * - Objectid of the subvolume root + * - Generation number of the tree holding the reference + * - objectid of the file holding the reference + * - number of references holding by parent node (alway 1 for tree blocks) + * + * Btree leaf may hold multiple references to a file extent. In most cases, + * these references are from same file and the corresponding offsets inside + * the file are close together. + * + * When a file extent is allocated the fields are filled in: + * (root_key.objectid, trans->transid, inode objectid, 1) + * + * When a leaf is cow'd new references are added for every file extent found + * in the leaf. It looks similar to the create case, but trans->transid will + * be different when the block is cow'd. + * + * (root_key.objectid, trans->transid, inode objectid, + * number of references in the leaf) + * + * When a file extent is removed either during snapshot deletion or + * file truncation, we find the corresponding back reference and check + * the following fields: + * + * (btrfs_header_owner(leaf), btrfs_header_generation(leaf), + * inode objectid) + * + * Btree extents can be referenced by: + * + * - Different subvolumes + * - Different generations of the same subvolume + * + * When a tree block is created, back references are inserted: + * + * (root->root_key.objectid, trans->transid, level, 1) + * + * When a tree block is cow'd, new back references are added for all the + * blocks it points to. If the tree block isn't in reference counted root, + * the old back references are removed. These new back references are of + * the form (trans->transid will have increased since creation): + * + * (root->root_key.objectid, trans->transid, level, 1) + * + * When a backref is in deleting, the following fields are checked: + * + * if backref was for a tree root: + * (btrfs_header_owner(itself), btrfs_header_generation(itself), level) + * else + * (btrfs_header_owner(parent), btrfs_header_generation(parent), level) + * + * Back Reference Key composing: + * + * The key objectid corresponds to the first byte in the extent, the key + * type is set to BTRFS_EXTENT_REF_KEY, and the key offset is the first + * byte of parent extent. If a extent is tree root, the key offset is set + * to the key objectid. + */ + +static noinline int lookup_extent_backref(struct btrfs_trans_handle *trans, + struct btrfs_root *root, + struct btrfs_path *path, + u64 bytenr, u64 parent, + u64 ref_root, u64 ref_generation, + u64 owner_objectid, int del) +{ + struct btrfs_key key; + struct btrfs_extent_ref *ref; + struct extent_buffer *leaf; + u64 ref_objectid; + int ret; + + key.objectid = bytenr; + key.type = BTRFS_EXTENT_REF_KEY; + key.offset = parent; + + ret = btrfs_search_slot(trans, root, &key, path, del ? -1 : 0, 1); + if (ret < 0) + goto out; + if (ret > 0) { + ret = -ENOENT; + goto out; + } + + leaf = path->nodes[0]; + ref = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_extent_ref); + ref_objectid = btrfs_ref_objectid(leaf, ref); + if (btrfs_ref_root(leaf, ref) != ref_root || + btrfs_ref_generation(leaf, ref) != ref_generation || + (ref_objectid != owner_objectid && + ref_objectid != BTRFS_MULTIPLE_OBJECTIDS)) { + ret = -EIO; + WARN_ON(1); + goto out; + } + ret = 0; +out: + return ret; +} + +/* + * updates all the backrefs that are pending on update_list for the + * extent_root + */ +static noinline int update_backrefs(struct btrfs_trans_handle *trans, + struct btrfs_root *extent_root, + struct btrfs_path *path, + struct list_head *update_list) +{ + struct btrfs_key key; + struct btrfs_extent_ref *ref; + struct btrfs_fs_info *info = extent_root->fs_info; + struct pending_extent_op *op; + struct extent_buffer *leaf; + int ret = 0; + struct list_head *cur = update_list->next; + u64 ref_objectid; + u64 ref_root = extent_root->root_key.objectid; + + op = list_entry(cur, struct pending_extent_op, list); + +search: + key.objectid = op->bytenr; + key.type = BTRFS_EXTENT_REF_KEY; + key.offset = op->orig_parent; + + ret = btrfs_search_slot(trans, extent_root, &key, path, 0, 1); + BUG_ON(ret); + + leaf = path->nodes[0]; + +loop: + ref = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_extent_ref); + + ref_objectid = btrfs_ref_objectid(leaf, ref); + + if (btrfs_ref_root(leaf, ref) != ref_root || + btrfs_ref_generation(leaf, ref) != op->orig_generation || + (ref_objectid != op->level && + ref_objectid != BTRFS_MULTIPLE_OBJECTIDS)) { + printk(KERN_ERR "btrfs couldn't find %llu, parent %llu, " + "root %llu, owner %u\n", + (unsigned long long)op->bytenr, + (unsigned long long)op->orig_parent, + (unsigned long long)ref_root, op->level); + btrfs_print_leaf(extent_root, leaf); + BUG(); + } + + key.objectid = op->bytenr; + key.offset = op->parent; + key.type = BTRFS_EXTENT_REF_KEY; + ret = btrfs_set_item_key_safe(trans, extent_root, path, &key); + BUG_ON(ret); + ref = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_extent_ref); + btrfs_set_ref_generation(leaf, ref, op->generation); + + cur = cur->next; + + list_del_init(&op->list); + unlock_extent(&info->extent_ins, op->bytenr, + op->bytenr + op->num_bytes - 1, GFP_NOFS); + kfree(op); + + if (cur == update_list) { + btrfs_mark_buffer_dirty(path->nodes[0]); + btrfs_release_path(extent_root, path); + goto out; + } + + op = list_entry(cur, struct pending_extent_op, list); + + path->slots[0]++; + while (path->slots[0] < btrfs_header_nritems(leaf)) { + btrfs_item_key_to_cpu(leaf, &key, path->slots[0]); + if (key.objectid == op->bytenr && + key.type == BTRFS_EXTENT_REF_KEY) + goto loop; + path->slots[0]++; + } + + btrfs_mark_buffer_dirty(path->nodes[0]); + btrfs_release_path(extent_root, path); + goto search; + +out: + return 0; +} + +static noinline int insert_extents(struct btrfs_trans_handle *trans, + struct btrfs_root *extent_root, + struct btrfs_path *path, + struct list_head *insert_list, int nr) +{ + struct btrfs_key *keys; + u32 *data_size; + struct pending_extent_op *op; + struct extent_buffer *leaf; + struct list_head *cur = insert_list->next; + struct btrfs_fs_info *info = extent_root->fs_info; + u64 ref_root = extent_root->root_key.objectid; + int i = 0, last = 0, ret; + int total = nr * 2; + + if (!nr) + return 0; + + keys = kzalloc(total * sizeof(struct btrfs_key), GFP_NOFS); + if (!keys) + return -ENOMEM; + + data_size = kzalloc(total * sizeof(u32), GFP_NOFS); + if (!data_size) { + kfree(keys); + return -ENOMEM; + } + + list_for_each_entry(op, insert_list, list) { + keys[i].objectid = op->bytenr; + keys[i].offset = op->num_bytes; + keys[i].type = BTRFS_EXTENT_ITEM_KEY; + data_size[i] = sizeof(struct btrfs_extent_item); + i++; + + keys[i].objectid = op->bytenr; + keys[i].offset = op->parent; + keys[i].type = BTRFS_EXTENT_REF_KEY; + data_size[i] = sizeof(struct btrfs_extent_ref); + i++; + } + + op = list_entry(cur, struct pending_extent_op, list); + i = 0; + while (i < total) { + int c; + ret = btrfs_insert_some_items(trans, extent_root, path, + keys+i, data_size+i, total-i); + BUG_ON(ret < 0); + + if (last && ret > 1) + BUG(); + + leaf = path->nodes[0]; + for (c = 0; c < ret; c++) { + int ref_first = keys[i].type == BTRFS_EXTENT_REF_KEY; + + /* + * if the first item we inserted was a backref, then + * the EXTENT_ITEM will be the odd c's, else it will + * be the even c's + */ + if ((ref_first && (c % 2)) || + (!ref_first && !(c % 2))) { + struct btrfs_extent_item *itm; + + itm = btrfs_item_ptr(leaf, path->slots[0] + c, + struct btrfs_extent_item); + btrfs_set_extent_refs(path->nodes[0], itm, 1); + op->del++; + } else { + struct btrfs_extent_ref *ref; + + ref = btrfs_item_ptr(leaf, path->slots[0] + c, + struct btrfs_extent_ref); + btrfs_set_ref_root(leaf, ref, ref_root); + btrfs_set_ref_generation(leaf, ref, + op->generation); + btrfs_set_ref_objectid(leaf, ref, op->level); + btrfs_set_ref_num_refs(leaf, ref, 1); + op->del++; + } + + /* + * using del to see when its ok to free up the + * pending_extent_op. In the case where we insert the + * last item on the list in order to help do batching + * we need to not free the extent op until we actually + * insert the extent_item + */ + if (op->del == 2) { + unlock_extent(&info->extent_ins, op->bytenr, + op->bytenr + op->num_bytes - 1, + GFP_NOFS); + cur = cur->next; + list_del_init(&op->list); + kfree(op); + if (cur != insert_list) + op = list_entry(cur, + struct pending_extent_op, + list); + } + } + btrfs_mark_buffer_dirty(leaf); + btrfs_release_path(extent_root, path); + + /* + * Ok backref's and items usually go right next to eachother, + * but if we could only insert 1 item that means that we + * inserted on the end of a leaf, and we have no idea what may + * be on the next leaf so we just play it safe. In order to + * try and help this case we insert the last thing on our + * insert list so hopefully it will end up being the last + * thing on the leaf and everything else will be before it, + * which will let us insert a whole bunch of items at the same + * time. + */ + if (ret == 1 && !last && (i + ret < total)) { + /* + * last: where we will pick up the next time around + * i: our current key to insert, will be total - 1 + * cur: the current op we are screwing with + * op: duh + */ + last = i + ret; + i = total - 1; + cur = insert_list->prev; + op = list_entry(cur, struct pending_extent_op, list); + } else if (last) { + /* + * ok we successfully inserted the last item on the + * list, lets reset everything + * + * i: our current key to insert, so where we left off + * last time + * last: done with this + * cur: the op we are messing with + * op: duh + * total: since we inserted the last key, we need to + * decrement total so we dont overflow + */ + i = last; + last = 0; + total--; + if (i < total) { + cur = insert_list->next; + op = list_entry(cur, struct pending_extent_op, + list); + } + } else { + i += ret; + } + + cond_resched(); + } + ret = 0; + kfree(keys); + kfree(data_size); + return ret; +} + +static noinline int insert_extent_backref(struct btrfs_trans_handle *trans, + struct btrfs_root *root, + struct btrfs_path *path, + u64 bytenr, u64 parent, + u64 ref_root, u64 ref_generation, + u64 owner_objectid) +{ + struct btrfs_key key; + struct extent_buffer *leaf; + struct btrfs_extent_ref *ref; + u32 num_refs; + int ret; + + key.objectid = bytenr; + key.type = BTRFS_EXTENT_REF_KEY; + key.offset = parent; + + ret = btrfs_insert_empty_item(trans, root, path, &key, sizeof(*ref)); + if (ret == 0) { + leaf = path->nodes[0]; + ref = btrfs_item_ptr(leaf, path->slots[0], + struct btrfs_extent_ref); + btrfs_set_ref_root(leaf, ref, ref_root); + btrfs_set_ref_generation(leaf, ref, ref_generation); + btrfs_set_ref_objectid(leaf, ref, owner_objectid); + btrfs_set_ref_num_refs(leaf, ref, 1); + } else if (ret == -EEXIST) { + u64 existing_owner; + BUG_ON(owner_objectid < BTRFS_FIRST_FREE_OBJECTID); + leaf = path->nodes[0]; + ref = btrfs_item_ptr(leaf, path->slots[0], + struct btrfs_extent_ref); + if (btrfs_ref_root(leaf, ref) != ref_root || + btrfs_ref_generation(leaf, ref) != ref_generation) { + ret = -EIO; + WARN_ON(1); + goto out; + } + + num_refs = btrfs_ref_num_refs(leaf, ref); + BUG_ON(num_refs == 0); + btrfs_set_ref_num_refs(leaf, ref, num_refs + 1); + + existing_owner = btrfs_ref_objectid(leaf, ref); + if (existing_owner != owner_objectid && + existing_owner != BTRFS_MULTIPLE_OBJECTIDS) { + btrfs_set_ref_objectid(leaf, ref, + BTRFS_MULTIPLE_OBJECTIDS); + } + ret = 0; + } else { + goto out; + } + btrfs_mark_buffer_dirty(path->nodes[0]); +out: + btrfs_release_path(root, path); + return ret; +} + +static noinline int remove_extent_backref(struct btrfs_trans_handle *trans, + struct btrfs_root *root, + struct btrfs_path *path) +{ + struct extent_buffer *leaf; + struct btrfs_extent_ref *ref; + u32 num_refs; + int ret = 0; + + leaf = path->nodes[0]; + ref = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_extent_ref); + num_refs = btrfs_ref_num_refs(leaf, ref); + BUG_ON(num_refs == 0); + num_refs -= 1; + if (num_refs == 0) { + ret = btrfs_del_item(trans, root, path); + } else { + btrfs_set_ref_num_refs(leaf, ref, num_refs); + btrfs_mark_buffer_dirty(leaf); + } + btrfs_release_path(root, path); + return ret; +} + +#ifdef BIO_RW_DISCARD +static void btrfs_issue_discard(struct block_device *bdev, + u64 start, u64 len) +{ + blkdev_issue_discard(bdev, start >> 9, len >> 9, GFP_KERNEL); +} +#endif + +static int btrfs_discard_extent(struct btrfs_root *root, u64 bytenr, + u64 num_bytes) +{ +#ifdef BIO_RW_DISCARD + int ret; + u64 map_length = num_bytes; + struct btrfs_multi_bio *multi = NULL; + + /* Tell the block device(s) that the sectors can be discarded */ + ret = btrfs_map_block(&root->fs_info->mapping_tree, READ, + bytenr, &map_length, &multi, 0); + if (!ret) { + struct btrfs_bio_stripe *stripe = multi->stripes; + int i; + + if (map_length > num_bytes) + map_length = num_bytes; + + for (i = 0; i < multi->num_stripes; i++, stripe++) { + btrfs_issue_discard(stripe->dev->bdev, + stripe->physical, + map_length); + } + kfree(multi); + } + + return ret; +#else + return 0; +#endif +} + +static noinline int free_extents(struct btrfs_trans_handle *trans, + struct btrfs_root *extent_root, + struct list_head *del_list) +{ + struct btrfs_fs_info *info = extent_root->fs_info; + struct btrfs_path *path; + struct btrfs_key key, found_key; + struct extent_buffer *leaf; + struct list_head *cur; + struct pending_extent_op *op; + struct btrfs_extent_item *ei; + int ret, num_to_del, extent_slot = 0, found_extent = 0; + u32 refs; + u64 bytes_freed = 0; + + path = btrfs_alloc_path(); + if (!path) + return -ENOMEM; + path->reada = 1; + +search: + /* search for the backref for the current ref we want to delete */ + cur = del_list->next; + op = list_entry(cur, struct pending_extent_op, list); + ret = lookup_extent_backref(trans, extent_root, path, op->bytenr, + op->orig_parent, + extent_root->root_key.objectid, + op->orig_generation, op->level, 1); + if (ret) { + printk(KERN_ERR "btrfs unable to find backref byte nr %llu " + "root %llu gen %llu owner %u\n", + (unsigned long long)op->bytenr, + (unsigned long long)extent_root->root_key.objectid, + (unsigned long long)op->orig_generation, op->level); + btrfs_print_leaf(extent_root, path->nodes[0]); + WARN_ON(1); + goto out; + } + + extent_slot = path->slots[0]; + num_to_del = 1; + found_extent = 0; + + /* + * if we aren't the first item on the leaf we can move back one and see + * if our ref is right next to our extent item + */ + if (likely(extent_slot)) { + extent_slot--; + btrfs_item_key_to_cpu(path->nodes[0], &found_key, + extent_slot); + if (found_key.objectid == op->bytenr && + found_key.type == BTRFS_EXTENT_ITEM_KEY && + found_key.offset == op->num_bytes) { + num_to_del++; + found_extent = 1; + } + } + + /* + * if we didn't find the extent we need to delete the backref and then + * search for the extent item key so we can update its ref count + */ + if (!found_extent) { + key.objectid = op->bytenr; + key.type = BTRFS_EXTENT_ITEM_KEY; + key.offset = op->num_bytes; + + ret = remove_extent_backref(trans, extent_root, path); + BUG_ON(ret); + btrfs_release_path(extent_root, path); + ret = btrfs_search_slot(trans, extent_root, &key, path, -1, 1); + BUG_ON(ret); + extent_slot = path->slots[0]; + } + + /* this is where we update the ref count for the extent */ + leaf = path->nodes[0]; + ei = btrfs_item_ptr(leaf, extent_slot, struct btrfs_extent_item); + refs = btrfs_extent_refs(leaf, ei); + BUG_ON(refs == 0); + refs--; + btrfs_set_extent_refs(leaf, ei, refs); + + btrfs_mark_buffer_dirty(leaf); + + /* + * This extent needs deleting. The reason cur_slot is extent_slot + + * num_to_del is because extent_slot points to the slot where the extent + * is, and if the backref was not right next to the extent we will be + * deleting at least 1 item, and will want to start searching at the + * slot directly next to extent_slot. However if we did find the + * backref next to the extent item them we will be deleting at least 2 + * items and will want to start searching directly after the ref slot + */ + if (!refs) { + struct list_head *pos, *n, *end; + int cur_slot = extent_slot+num_to_del; + u64 super_used; + u64 root_used; + + path->slots[0] = extent_slot; + bytes_freed = op->num_bytes; + + mutex_lock(&info->pinned_mutex); + ret = pin_down_bytes(trans, extent_root, op->bytenr, + op->num_bytes, op->level >= + BTRFS_FIRST_FREE_OBJECTID); + mutex_unlock(&info->pinned_mutex); + BUG_ON(ret < 0); + op->del = ret; + + /* + * we need to see if we can delete multiple things at once, so + * start looping through the list of extents we are wanting to + * delete and see if their extent/backref's are right next to + * eachother and the extents only have 1 ref + */ + for (pos = cur->next; pos != del_list; pos = pos->next) { + struct pending_extent_op *tmp; + + tmp = list_entry(pos, struct pending_extent_op, list); + + /* we only want to delete extent+ref at this stage */ + if (cur_slot >= btrfs_header_nritems(leaf) - 1) + break; + + btrfs_item_key_to_cpu(leaf, &found_key, cur_slot); + if (found_key.objectid != tmp->bytenr || + found_key.type != BTRFS_EXTENT_ITEM_KEY || + found_key.offset != tmp->num_bytes) + break; + + /* check to make sure this extent only has one ref */ + ei = btrfs_item_ptr(leaf, cur_slot, + struct btrfs_extent_item); + if (btrfs_extent_refs(leaf, ei) != 1) + break; + + btrfs_item_key_to_cpu(leaf, &found_key, cur_slot+1); + if (found_key.objectid != tmp->bytenr || + found_key.type != BTRFS_EXTENT_REF_KEY || + found_key.offset != tmp->orig_parent) + break; + + /* + * the ref is right next to the extent, we can set the + * ref count to 0 since we will delete them both now + */ + btrfs_set_extent_refs(leaf, ei, 0); + + /* pin down the bytes for this extent */ + mutex_lock(&info->pinned_mutex); + ret = pin_down_bytes(trans, extent_root, tmp->bytenr, + tmp->num_bytes, tmp->level >= + BTRFS_FIRST_FREE_OBJECTID); + mutex_unlock(&info->pinned_mutex); + BUG_ON(ret < 0); + + /* + * use the del field to tell if we need to go ahead and + * free up the extent when we delete the item or not. + */ + tmp->del = ret; + bytes_freed += tmp->num_bytes; + + num_to_del += 2; + cur_slot += 2; + } + end = pos; + + /* update the free space counters */ + spin_lock(&info->delalloc_lock); + super_used = btrfs_super_bytes_used(&info->super_copy); + btrfs_set_super_bytes_used(&info->super_copy, + super_used - bytes_freed); + + root_used = btrfs_root_used(&extent_root->root_item); + btrfs_set_root_used(&extent_root->root_item, + root_used - bytes_freed); + spin_unlock(&info->delalloc_lock); + + /* delete the items */ + ret = btrfs_del_items(trans, extent_root, path, + path->slots[0], num_to_del); + BUG_ON(ret); + + /* + * loop through the extents we deleted and do the cleanup work + * on them + */ + for (pos = cur, n = pos->next; pos != end; + pos = n, n = pos->next) { + struct pending_extent_op *tmp; + tmp = list_entry(pos, struct pending_extent_op, list); + + /* + * remember tmp->del tells us wether or not we pinned + * down the extent + */ + ret = update_block_group(trans, extent_root, + tmp->bytenr, tmp->num_bytes, 0, + tmp->del); + BUG_ON(ret); + + list_del_init(&tmp->list); + unlock_extent(&info->extent_ins, tmp->bytenr, + tmp->bytenr + tmp->num_bytes - 1, + GFP_NOFS); + kfree(tmp); + } + } else if (refs && found_extent) { + /* + * the ref and extent were right next to eachother, but the + * extent still has a ref, so just free the backref and keep + * going + */ + ret = remove_extent_backref(trans, extent_root, path); + BUG_ON(ret); + + list_del_init(&op->list); + unlock_extent(&info->extent_ins, op->bytenr, + op->bytenr + op->num_bytes - 1, GFP_NOFS); + kfree(op); + } else { + /* + * the extent has multiple refs and the backref we were looking + * for was not right next to it, so just unlock and go next, + * we're good to go + */ + list_del_init(&op->list); + unlock_extent(&info->extent_ins, op->bytenr, + op->bytenr + op->num_bytes - 1, GFP_NOFS); + kfree(op); + } + + btrfs_release_path(extent_root, path); + if (!list_empty(del_list)) + goto search; + +out: + btrfs_free_path(path); + return ret; +} + +static int __btrfs_update_extent_ref(struct btrfs_trans_handle *trans, + struct btrfs_root *root, u64 bytenr, + u64 orig_parent, u64 parent, + u64 orig_root, u64 ref_root, + u64 orig_generation, u64 ref_generation, + u64 owner_objectid) +{ + int ret; + struct btrfs_root *extent_root = root->fs_info->extent_root; + struct btrfs_path *path; + + if (root == root->fs_info->extent_root) { + struct pending_extent_op *extent_op; + u64 num_bytes; + + BUG_ON(owner_objectid >= BTRFS_MAX_LEVEL); + num_bytes = btrfs_level_size(root, (int)owner_objectid); + mutex_lock(&root- |