/* * Copyright (C) 2007,2008 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/slab.h> #include "ctree.h" #include "disk-io.h" #include "transaction.h" #include "print-tree.h" #include "locking.h" static int split_node(struct btrfs_trans_handle *trans, struct btrfs_root *root, struct btrfs_path *path, int level); static int split_leaf(struct btrfs_trans_handle *trans, struct btrfs_root *root, struct btrfs_key *ins_key, struct btrfs_path *path, int data_size, int extend); static int push_node_left(struct btrfs_trans_handle *trans, struct btrfs_root *root, struct extent_buffer *dst, struct extent_buffer *src, int empty); static int balance_node_right(struct btrfs_trans_handle *trans, struct btrfs_root *root, struct extent_buffer *dst_buf, struct extent_buffer *src_buf); static int del_ptr(struct btrfs_trans_handle *trans, struct btrfs_root *root, struct btrfs_path *path, int level, int slot); struct btrfs_path *btrfs_alloc_path(void) { struct btrfs_path *path; path = kmem_cache_zalloc(btrfs_path_cachep, GFP_NOFS); return path; } /* * set all locked nodes in the path to blocking locks. This should * be done before scheduling */ noinline void btrfs_set_path_blocking(struct btrfs_path *p) { int i; for (i = 0; i < BTRFS_MAX_LEVEL; i++) { if (!p->nodes[i] || !p->locks[i]) continue; btrfs_set_lock_blocking_rw(p->nodes[i], p->locks[i]); if (p->locks[i] == BTRFS_READ_LOCK) p->locks[i] = BTRFS_READ_LOCK_BLOCKING; else if (p->locks[i] == BTRFS_WRITE_LOCK) p->locks[i] = BTRFS_WRITE_LOCK_BLOCKING; } } /* * reset all the locked nodes in the patch to spinning locks. * * held is used to keep lockdep happy, when lockdep is enabled * we set held to a blocking lock before we go around and * retake all the spinlocks in the path. You can safely use NULL * for held */ noinline void btrfs_clear_path_blocking(struct btrfs_path *p, struct extent_buffer *held, int held_rw) { int i; #ifdef CONFIG_DEBUG_LOCK_ALLOC /* lockdep really cares that we take all of these spinlocks * in the right order. If any of the locks in the path are not * currently blocking, it is going to complain. So, make really * really sure by forcing the path to blocking before we clear * the path blocking. */ if (held) { btrfs_set_lock_blocking_rw(held, held_rw); if (held_rw == BTRFS_WRITE_LOCK) held_rw = BTRFS_WRITE_LOCK_BLOCKING; else if (held_rw == BTRFS_READ_LOCK) held_rw = BTRFS_READ_LOCK_BLOCKING; } btrfs_set_path_blocking(p); #endif for (i = BTRFS_MAX_LEVEL - 1; i >= 0; i--) { if (p->nodes[i] && p->locks[i]) { btrfs_clear_lock_blocking_rw(p->nodes[i], p->locks[i]); if (p->locks[i] == BTRFS_WRITE_LOCK_BLOCKING) p->locks[i] = BTRFS_WRITE_LOCK; else if (p->locks[i] == BTRFS_READ_LOCK_BLOCKING) p->locks[i] = BTRFS_READ_LOCK; } } #ifdef CONFIG_DEBUG_LOCK_ALLOC if (held) btrfs_clear_lock_blocking_rw(held, held_rw); #endif } /* this also releases the path */ void btrfs_free_path(struct btrfs_path *p) { if (!p) return; btrfs_release_path(p); kmem_cache_free(btrfs_path_cachep, p); } /* * path release drops references on the extent buffers in the path * and it drops any locks held by this path * * It is safe to call this on paths that no locks or extent buffers held. */ noinline void btrfs_release_path(struct btrfs_path *p) { int i; for (i = 0; i < BTRFS_MAX_LEVEL; i++) { p->slots[i] = 0; if (!p->nodes[i]) continue; if (p->locks[i]) { btrfs_tree_unlock_rw(p->nodes[i], p->locks[i]); p->locks[i] = 0; } free_extent_buffer(p->nodes[i]); p->nodes[i] = NULL; } } /* * safely gets a reference on the root node of a tree. A lock * is not taken, so a concurrent writer may put a different node * at the root of the tree. See btrfs_lock_root_node for the * looping required. * * The extent buffer returned by this has a reference taken, so * it won't disappear. It may stop being the root of the tree * at any time because there are no locks held. */ struct extent_buffer *btrfs_root_node(struct btrfs_root *root) { struct extent_buffer *eb; rcu_read_lock(); eb = rcu_dereference(root->node); extent_buffer_get(eb); rcu_read_unlock(); return eb; } /* loop around taking references on and locking the root node of the * tree until you end up with a lock on the root. A locked buffer * is returned, with a reference held. */ struct extent_buffer *btrfs_lock_root_node(struct btrfs_root *root) { struct extent_buffer *eb; while (1) { eb = btrfs_root_node(root); btrfs_tree_lock(eb); if (eb == root->node) break; btrfs_tree_unlock(eb); free_extent_buffer(eb); } return eb; } /* loop around taking references on and locking the root node of the * tree until you end up with a lock on the root. A locked buffer * is returned, with a reference held. */ struct extent_buffer *btrfs_read_lock_root_node(struct btrfs_root *root) { struct extent_buffer *eb; while (1) { eb = btrfs_root_node(root); btrfs_tree_read_lock(eb); if (eb == root->node) break; btrfs_tree_read_unlock(eb); free_extent_buffer(eb); } return eb; } /* cowonly root (everything not a reference counted cow subvolume), just get * put onto a simple dirty list. transaction.c walks this to make sure they * get properly updated on disk. */ static void add_root_to_dirty_list(struct btrfs_root *root) { if (root->track_dirty && list_empty(&root->dirty_list)) { list_add(&root->dirty_list, &root->fs_info->dirty_cowonly_roots); } } /* * used by snapshot creation to make a copy of a root for a tree with * a given objectid. The buffer with the new root node is returned in * cow_ret, and this func returns zero on success or a negative error code. */ int btrfs_copy_root(struct btrfs_trans_handle *trans, struct btrfs_root *root, struct extent_buffer *buf, struct extent_buffer **cow_ret, u64 new_root_objectid) { struct extent_buffer *cow; int ret = 0; int level; struct btrfs_disk_key disk_key; WARN_ON(root->ref_cows && trans->transid != root->fs_info->running_transaction->transid); WARN_ON(root->ref_cows && trans->transid != root->last_trans); level = btrfs_header_level(buf); if (level == 0) btrfs_item_key(buf, &disk_key, 0); else btrfs_node_key(buf, &disk_key, 0); cow = btrfs_alloc_free_block(trans, root, buf->len, 0, new_root_objectid, &disk_key, level, buf->start, 0, 1); if (IS_ERR(cow)) return PTR_ERR(cow); copy_extent_buffer(cow, buf, 0, 0, cow->len); btrfs_set_header_bytenr(cow, cow->start); btrfs_set_header_generation(cow, trans->transid); btrfs_set_header_backref_rev(cow, BTRFS_MIXED_BACKREF_REV); btrfs_clear_header_flag(cow, BTRFS_HEADER_FLAG_WRITTEN | BTRFS_HEADER_FLAG_RELOC); if (new_root_objectid == BTRFS_TREE_RELOC_OBJECTID) btrfs_set_header_flag(cow, BTRFS_HEADER_FLAG_RELOC); else btrfs_set_header_owner(cow, new_root_objectid); write_extent_buffer(cow, root->fs_info->fsid, (unsigned long)btrfs_header_fsid(cow), BTRFS_FSID_SIZE); WARN_ON(btrfs_header_generation(buf) > trans->transid); if (new_root_objectid == BTRFS_TREE_RELOC_OBJECTID) ret = btrfs_inc_ref(trans, root, cow, 1, 1); else ret = btrfs_inc_ref(trans, root, cow, 0, 1); if (ret) return ret; btrfs_mark_buffer_dirty(cow); *cow_ret = cow; return 0; } /* * check if the tree block can be shared by multiple trees */ int btrfs_block_can_be_shared(struct btrfs_root *root, struct extent_buffer *buf) { /* * Tree blocks not in refernece counted trees and tree roots * are never shared. If a block was allocated after the last * snapshot and the block was not allocated by tree relocation, * we know the block is not shared. */ if (root->ref_cows && buf != root->node && buf != root->commit_root && (btrfs_header_generation(buf) <= btrfs_root_last_snapshot(&root->root_item) || btrfs_header_flag(buf, BTRFS_HEADER_FLAG_RELOC))) return 1; #ifdef BTRFS_COMPAT_EXTENT_TREE_V0 if (root->ref_cows && btrfs_header_backref_rev(buf) < BTRFS_MIXED_BACKREF_REV) return 1; #endif return 0; } static noinline int update_ref_for_cow(struct btrfs_trans_handle *trans, struct btrfs_root *root, struct extent_buffer *buf, struct extent_buffer *cow, int *last_ref) { u64 refs; u64 owner; u64 flags; u64 new_flags = 0; int ret; /* * Backrefs update rules: * * Always use full backrefs for extent pointers in tree block * allocated by tree relocation. * * If a shared tree block is no longer referenced by its owner * tree (btrfs_header_owner(buf) == root->root_key.objectid), * use full backrefs for extent pointers in tree block. * * If a tree block is been relocating * (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID), * use full backrefs for extent pointers in tree block. * The reason for this is some operations (such as drop tree) * are only allowed for blocks use full backrefs. */ if (btrfs_block_can_be_shared(root, buf)) { ret = btrfs_lookup_extent_info(trans, root, buf->start, buf->len, &refs, &flags); BUG_ON(ret); BUG_ON(refs == 0); } else { refs = 1; if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID || btrfs_header_backref_rev(buf) < BTRFS_MIXED_BACKREF_REV) flags = BTRFS_BLOCK_FLAG_FULL_BACKREF; else flags = 0; } owner = btrfs_header_owner(buf); BUG_ON(owner == BTRFS_TREE_RELOC_OBJECTID && !(flags & BTRFS_BLOCK_FLAG_FULL_BACKREF)); if (refs > 1) { if ((owner == root->root_key.objectid || root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID) && !(flags & BTRFS_BLOCK_FLAG_FULL_BACKREF)) { ret = btrfs_inc_ref(trans, root, buf, 1, 1); BUG_ON(ret); if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID) { ret = btrfs_dec_ref(trans, root, buf, 0, 1); BUG_ON(ret); ret = btrfs_inc_ref(trans, root, cow, 1, 1); BUG_ON(ret); } new_flags |= BTRFS_BLOCK_FLAG_FULL_BACKREF; } else { if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID) ret = btrfs_inc_ref(trans, root, cow, 1, 1); else ret = btrfs_inc_ref(trans, root, cow, 0, 1); BUG_ON(ret); } if (new_flags != 0) { ret = btrfs_set_disk_extent_flags(trans, root, buf->start, buf->len, new_flags, 0); BUG_ON(ret); } } else { if (flags & BTRFS_BLOCK_FLAG_FULL_BACKREF) { if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID) ret = btrfs_inc_ref(trans, root, cow, 1, 1); else ret = btrfs_inc_ref(trans, root, cow, 0, 1); BUG_ON(ret); ret = btrfs_dec_ref(trans, root, buf, 1, 1); BUG_ON(ret); } clean_tree_block(trans, root, buf); *last_ref = 1; } return 0; } /* * does the dirty work in cow of a single block. The parent block (if * supplied) is updated to point to the new cow copy. The new buffer is marked * dirty and returned locked. If you modify the block it needs to be marked * dirty again. * * search_start -- an allocation hint for the new block * * empty_size -- a hint that you plan on doing more cow. This is the size in * bytes the allocator should try to find free next to the block it returns. * This is just a hint and may be ignored by the allocator. */ static noinline int __btrfs_cow_block(struct btrfs_trans_handle *trans, struct btrfs_root *root, struct extent_buffer *buf, struct extent_buffer *parent, int parent_slot, struct extent_buffer **cow_ret, u64 search_start, u64 empty_size) { struct btrfs_disk_key disk_key; struct extent_buffer *cow; int level; int last_ref = 0; int unlock_orig = 0; u64 parent_start; if (*cow_ret == buf) unlock_orig = 1; btrfs_assert_tree_locked(buf); WARN_ON(root->ref_cows && trans->transid != root->fs_info->running_transaction->transid); WARN_ON(root->ref_cows && trans->transid != root->last_trans); level = btrfs_header_level(buf); if (level == 0) btrfs_item_key(buf, &disk_key, 0); else btrfs_node_key(buf, &disk_key, 0); if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID) { if (parent) parent_start = parent->start; else parent_start = 0; } else parent_start = 0; cow = btrfs_alloc_free_block(trans, root, buf->len, parent_start, root->root_key.objectid, &disk_key, level, search_start, empty_size, 1); if (IS_ERR(cow)) return PTR_ERR(cow); /* cow is set to blocking by btrfs_init_new_buffer */ copy_extent_buffer(cow, buf, 0, 0, cow->len); btrfs_set_header_bytenr(cow, cow->start); btrfs_set_header_generation(cow, trans->transid); btrfs_set_header_backref_rev(cow, BTRFS_MIXED_BACKREF_REV); btrfs_clear_header_flag(cow, BTRFS_HEADER_FLAG_WRITTEN | BTRFS_HEADER_FLAG_RELOC); if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID) btrfs_set_header_flag(cow, BTRFS_HEADER_FLAG_RELOC); else btrfs_set_header_owner(cow, root->root_key.objectid); write_extent_buffer(cow, root->fs_info->fsid, (unsigned long)btrfs_header_fsid(cow), BTRFS_FSID_SIZE); update_ref_for_cow(trans, root, buf, cow, &last_ref); if (root->ref_cows) btrfs_reloc_cow_block(trans, root, buf, cow); if (buf == root->node) { WARN_ON(parent && parent != buf); if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID || btrfs_header_backref_rev(buf) < BTRFS_MIXED_BACKREF_REV) parent_start = buf->start; else parent_start = 0; extent_buffer_get(cow); rcu_assign_pointer(root->node, cow); btrfs_free_tree_block(trans, root, buf, parent_start, last_ref, 1); free_extent_buffer(buf); add_root_to_dirty_list(root); } else { if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID) parent_start = parent->start; else parent_start = 0; WARN_ON(trans->transid != btrfs_header_generation(parent)); btrfs_set_node_blockptr(parent, parent_slot, cow->start); btrfs_set_node_ptr_generation(parent, parent_slot, trans->transid); btrfs_mark_buffer_dirty(parent); btrfs_free_tree_block(trans, root, buf, parent_start, last_ref, 1); } if (unlock_orig) btrfs_tree_unlock(buf); free_extent_buffer(buf); btrfs_mark_buffer_dirty(cow); *cow_ret = cow; return 0; } static inline int should_cow_block(struct btrfs_trans_handle *trans, struct btrfs_root *root, struct extent_buffer *buf) { /* ensure we can see the force_cow */ smp_rmb(); /* * We do not need to cow a block if * 1) this block is not created or changed in this transaction; * 2) this block does not belong to TREE_RELOC tree; * 3) the root is not forced COW. * * What is forced COW: * when we create snapshot during commiting the transaction, * after we've finished coping src root, we must COW the shared * block to ensure the metadata consistency. */ if (btrfs_header_generation(buf) == trans->transid && !btrfs_header_flag(buf, BTRFS_HEADER_FLAG_WRITTEN) && !(root->root_key.objectid != BTRFS_TREE_RELOC_OBJECTID && btrfs_header_flag(buf, BTRFS_HEADER_FLAG_RELOC)) && !root->force_cow) return 0; return 1; } /* * cows a single block, see __btrfs_cow_block for the real work. * This version of it has extra checks so that a block isn't cow'd more than * once per transaction, as long as it hasn't been written yet */ noinline int btrfs_cow_block(struct btrfs_trans_handle *trans, struct btrfs_root *root, struct extent_buffer *buf, struct extent_buffer *parent, int parent_slot, struct extent_buffer **cow_ret) { u64 search_start; int ret; if (trans->transaction != root->fs_info->running_transaction) { printk(KERN_CRIT "trans %llu running %llu\n", (unsigned long long)trans->transid, (unsigned long long) root->fs_info->running_transaction->transid); WARN_ON(1); } if (trans->transid != root->fs_info->generation) { printk(KERN_CRIT "trans %llu running %llu\n", (unsigned long long)trans->transid, (unsigned long long)root->fs_info->generation); WARN_ON(1); } if (!should_cow_block(trans, root, buf)) { *cow_ret = buf; return 0; } search_start = buf->start & ~((u64)(1024 * 1024 * 1024) - 1); if (parent) btrfs_set_lock_blocking(parent); btrfs_set_lock_blocking(buf); ret = __btrfs_cow_block(trans, root, buf, parent, parent_slot, cow_ret, search_start, 0); trace_btrfs_cow_block(root, buf, *cow_ret); return ret; } /* * helper function for defrag to decide if two blocks pointed to by a * node are actually close by */ static int close_blocks(u64 blocknr, u64 other, u32 blocksize) { if (blocknr < other && other - (blocknr + blocksize) < 32768) return 1; if (blocknr > other && blocknr - (other + blocksize) < 32768) return 1; return 0; } /* * compare two keys in a memcmp fashion */ static int comp_keys(struct btrfs_disk_key *disk, struct btrfs_key *k2) { struct btrfs_key k1; btrfs_disk_key_to_cpu(&k1, disk); return btrfs_comp_cpu_keys(&k1, k2); } /* * same as comp_keys only with two btrfs_key's */ int btrfs_comp_cpu_keys(struct btrfs_key *k1, struct btrfs_key *k2) { if (k1->objectid > k2->objectid) return 1; if (k1->objectid < k2->objectid) return -1; if (k1->type > k2->type) return 1; if (k1->type < k2->type) return -1; if (k1->offset > k2->offset) return 1; if (k1->offset < k2->offset) return -1; return 0; } /* * this is used by the defrag code to go through all the * leaves pointed to by a node and reallocate them so that * disk order is close to key order */ int btrfs_realloc_node(struct btrfs_trans_handle *trans, struct btrfs_root *root, struct extent_buffer *parent, int start_slot, int cache_only, u64 *last_ret, struct btrfs_key *progress) { struct extent_buffer *cur; u64 blocknr; u64 gen; u64 search_start = *last_ret; u64 last_block = 0; u64 other; u32 parent_nritems; int end_slot; int i; int err = 0; int parent_level; int uptodate; u32 blocksize; int progress_passed = 0; struct btrfs_disk_key disk_key; parent_level = btrfs_header_level(parent); if (cache_only && parent_level != 1) return 0; if (trans->transaction != root->fs_info->running_transaction) WARN_ON(1); if (trans->transid != root->fs_info->generation) WARN_ON(1); parent_nritems = btrfs_header_nritems(parent); blocksize = btrfs_level_size(root, parent_level - 1); end_slot = parent_nritems; if (parent_nritems == 1) return 0; btrfs_set_lock_blocking(parent); for (i = start_slot; i < end_slot; i++) { int close = 1; btrfs_node_key(parent, &disk_key, i); if (!progress_passed && comp_keys(&disk_key, progress) < 0) continue; progress_passed = 1; blocknr = btrfs_node_blockptr(parent, i); gen = btrfs_node_ptr_generation(parent, i); if (last_block == 0) last_block = blocknr; if (i > 0) { other = btrfs_node_blockptr(parent, i - 1); close = close_blocks(blocknr, other, blocksize); } if (!close && i < end_slot - 2) { other = btrfs_node_blockptr(parent, i + 1); close = close_blocks(blocknr, other, blocksize); } if (close) { last_block = blocknr; continue; } cur = btrfs_find_tree_block(root, blocknr, blocksize); if (cur) uptodate = btrfs_buffer_uptodate(cur, gen); else uptodate = 0; if (!cur || !uptodate) { if (cache_only) { free_extent_buffer(cur); continue; } if (!cur) { cur = read_tree_block(root, blocknr, blocksize, gen); if (!cur) return -EIO; } else if (!uptodate) { btrfs_read_buffer(cur, gen); } } if (search_start == 0) search_start = last_block; btrfs_tree_lock(cur); btrfs_set_lock_blocking(cur); err = __btrfs_cow_block(trans, root, cur, parent, i, &cur, search_start, min(16 * blocksize, (end_slot - i) * blocksize)); if (err) { btrfs_tree_unlock(cur); free_extent_buffer(cur); break; } search_start = cur->start; last_block = cur->start; *last_ret = search_start; btrfs_tree_unlock(cur); free_extent_buffer(cur); } return err; } /* * The leaf data grows from end-to-front in the node. * this returns the address of the start of the last item, * which is the stop of the leaf data stack */ static inline unsigned int leaf_data_end(struct btrfs_root *root, struct extent_buffer *leaf) { u32 nr = btrfs_header_nritems(leaf); if (nr == 0) return BTRFS_LEAF_DATA_SIZE(root); return btrfs_item_offset_nr(leaf, nr - 1); } /* * search for key in the extent_buffer. The items start at offset p, * and they are item_size apart. There are 'max' items in p. * * the slot in the array is returned via slot, and it points to * the place where you would insert key if it is not found in * the array. * * slot may point to max if the key is bigger than all of the keys */ static noinline int generic_bin_search(struct extent_buffer *eb, unsigned long p, int item_size, struct btrfs_key *key, int max, int *slot) { int low = 0; int high = max; int mid; int ret; struct btrfs_disk_key *tmp = NULL; struct btrfs_disk_key unaligned; unsigned long offset; char *kaddr = NULL; unsigned long map_start = 0; unsigned long map_len = 0; int err; while (low < high) { mid = (low + high) / 2; offset = p + mid * item_size; if (!kaddr || offset < map_start || (offset + sizeof(struct btrfs_disk_key)) > map_start + map_len) { err = map_private_extent_buffer(eb, offset, sizeof(struct btrfs_disk_key), &kaddr, &map_start, &map_len); if (!err) { tmp = (struct btrfs_disk_key *)(kaddr + offset - map_start); } else { read_extent_buffer(eb, &unaligned, offset, sizeof(unaligned)); tmp = &unaligned; } } else { tmp = (struct btrfs_disk_key *)(kaddr + offset - map_start); } ret = comp_keys(tmp, key); if (ret < 0) low = mid + 1; else if (ret > 0) high = mid; else { *slot = mid; return 0; } } *slot = low; return 1; } /* * simple bin_search frontend that does the right thing for * leaves vs nodes */ static int bin_search(struct extent_buffer *eb, struct btrfs_key *key, int level, int *slot) { if (level == 0) { return generic_bin_search(eb, offsetof(struct btrfs_leaf, items), sizeof(struct btrfs_item), key, btrfs_header_nritems(eb), slot); } else { return generic_bin_search(eb, offsetof(struct btrfs_node, ptrs), sizeof(struct btrfs_key_ptr), key, btrfs_header_nritems(eb), slot); } return -1; } int btrfs_bin_search(struct extent_buffer *eb, struct btrfs_key *key, int level, int *slot) { return bin_search(eb, key, level, slot); } static void root_add_used(struct btrfs_root *root, u32 size) { spin_lock(&root->accounting_lock); btrfs_set_root_used(&root->root_item, btrfs_root_used(&root->root_item) + size); spin_unlock(&root->accounting_lock); } static void root_sub_used(struct btrfs_root *root, u32 size) { spin_lock(&root->accounting_lock); btrfs_set_root_used(&root->root_item, btrfs_root_used(&root->root_item) - size); spin_unlock(&root->accounting_lock); } /* given a node and slot number, this reads the blocks it points to. The * extent buffer is returned with a reference taken (but unlocked). * NULL is returned on error. */ static noinline struct extent_buffer *read_node_slot(struct btrfs_root *root, struct extent_buffer *parent, int slot) { int level = btrfs_header_level(parent); if (slot < 0) return NULL; if (slot >= btrfs_header_nritems(parent)) return NULL; BUG_ON(level == 0); return read_tree_block(root, btrfs_node_blockptr(parent, slot), btrfs_level_size(root, level - 1), btrfs_node_ptr_generation(parent, slot)); } /* * node level balancing, used to make sure nodes are in proper order for * item deletion. We balance from the top down, so we have to make sure * that a deletion won't leave an node completely empty later on. */ static noinline int balance_level(struct btrfs_trans_handle *trans, struct btrfs_root *root, struct btrfs_path *path, int level) { struct extent_buffer *right = NULL; struct extent_buffer *mid; struct extent_buffer *left = NULL; struct extent_buffer *parent = NULL; int ret = 0; int wret; int pslot; int orig_slot = path->slots[level]; u64 orig_ptr; if (level == 0) return 0; mid = path->nodes[level]; WARN_ON(path->locks[level] != BTRFS_WRITE_LOCK && path->locks[level] != BTRFS_WRITE_LOCK_BLOCKING); WARN_ON(btrfs_header_generation(mid) != trans->transid); orig_ptr = btrfs_node_blockptr(mid, orig_slot); if (level < BTRFS_MAX_LEVEL - 1) { parent = path->nodes[level + 1]; pslot = path->slots[level + 1]; } /* * deal with the case where there is only one pointer in the root * by promoting the node below to a root */ if (!parent) { struct extent_buffer *child; if (btrfs_header_nritems(mid) != 1) return 0; /* promote the child to a root */ child = read_node_slot(root, mid, 0); BUG_ON(!child); btrfs_tree_lock(child); btrfs_set_lock_blocking(child); ret = btrfs_cow_block(trans, root, child, mid, 0, &child); if (ret) { btrfs_tree_unlock(child); free_extent_buffer(child); goto enospc; } rcu_assign_pointer(root->node, child); add_root_to_dirty_list(root); btrfs_tree_unlock(child); path->locks[level] = 0; path->nodes[level] = NULL; clean_tree_block(trans, root, mid); btrfs_tree_unlock(mid); /* once for the path */ free_extent_buffer(mid); root_sub_used(root, mid->len); btrfs_free_tree_block(trans, root, mid, 0, 1, 0); /* once for the root ptr */ free_extent_buffer(mid); return 0; } if (btrfs_header_nritems(mid) > BTRFS_NODEPTRS_PER_BLOCK(root) / 4) return 0; btrfs_header_nritems(mid); left = read_node_slot(root, parent, pslot - 1); if (left) { btrfs_tree_lock(left); btrfs_set_lock_blocking(left); wret = btrfs_cow_block(trans, root, left, parent, pslot - 1, &left); if (wret) { ret = wret; goto enospc; } } right = read_node_slot(root, parent, pslot + 1); if (right) { btrfs_tree_lock(right); btrfs_set_lock_blocking(right); wret = btrfs_cow_block(trans, root, right, parent, pslot + 1, &right); if (wret) { ret = wret; goto enospc; } } /* first, try to make some room in the middle buffer */ if (left) { orig_slot += btrfs_header_nritems(left); wret = push_node_left(trans, root, left, mid, 1); if (wret < 0) ret = wret; btrfs_header_nritems(mid); } /* * then try to empty the right most buffer into the middle */ if (right) { wret = push_node_left(trans, root, mid, right, 1); if (wret < 0 && wret != -ENOSPC) ret = wret; if (btrfs_header_nritems(right) == 0) { clean_tree_block(trans, root, right); btrfs_tree_unlock(right); wret = del_ptr(trans, root, path, level + 1, pslot + 1); if (wret) ret = wret; root_sub_used(root, right->len); btrfs_free_tree_block(trans, root, right, 0, 1, 0); free_extent_buffer(right); right = NULL; } else { struct btrfs_disk_key right_key; btrfs_node_key(right, &right_key, 0); btrfs_set_node_key(parent, &right_key, pslot + 1); btrfs_mark_buffer_dirty(parent); } } if (btrfs_header_nritems(mid) == 1) { /* * we're not allowed to leave a node with one item in the * tree during a delete. A deletion from lower in the tree * could try to delete the only pointer in this node. * So, pull some keys from the left. * There has to be a left pointer at this point because * otherwise we would have pulled some pointers from the * right */ BUG_ON(!left); wret = balance_node_right(trans, root, mid, left); if (wret < 0) { ret = wret; goto enospc; } if (wret == 1) { wret = push_node_left(trans, root, left, mid, 1); if (wret < 0) ret = wret; } BUG_ON(wret == 1); } if (btrfs_header_nritems(mid) == 0) { clean_tree_block(trans, root, mid); btrfs_tree_unlock(mid); wret = del_ptr(trans, root, path, level + 1, pslot); if (wret) ret = wret; root_sub_used(root, mid->len); btrfs_free_tree_block(trans, root, mid, 0, 1, 0); free_extent_buffer(mid); mid = NULL; } else { /* update the parent key to reflect our changes */ struct btrfs_disk_key mid_key; btrfs_node_key(mid, &mid_key, 0); btrfs_set_node_key(parent, &mid_key, pslot); btrfs_mark_buffer_dirty(parent); } /* update the path */ if (left) { if (btrfs_header_nritems(left) > orig_slot) { extent_buffer_get(left); /* left was locked after cow */ path->nodes[level] = left; path->slots[level + 1] -= 1; path->slots[level] = orig_slot; if (mid) { btrfs_tree_unlock(mid); free_extent_buffer(mid); } } else { orig_slot -= btrfs_header_nritems(left); path->slots[level] = orig_slot; } } /* double check we haven't messed things up */ if (orig_ptr != btrfs_node_blockptr(path->nodes[level], path->slots[level])) BUG(); enospc: if (right) { btrfs_tree_unlock(right); free_extent_buffer(right); } if (left) { if (path->nodes[level] != left) btrfs_tree_unlock(left); free_extent_buffer(left); } return ret; } /* Node balancing for insertion. Here we only split or push nodes around * when they are completely full. This is also done top down, so we * have to be pessimistic. */ static noinline int push_nodes_for_insert(struct btrfs_trans_handle *trans, struct btrfs_root *root, struct btrfs_path *path, int level) { struct extent_buffer *right = NULL; struct extent_buffer *mid; struct extent_buffer *left = NULL; struct extent_buffer *parent = NULL; int ret = 0; int wret; int pslot; int orig_slot = path->slots[level]; if (level == 0) return 1; mid = path->nodes[level]; WARN_ON(btrfs_header_generation(mid) != trans->transid); if (level < BTRFS_MAX_LEVEL - 1) { parent = path->nodes[level + 1]; pslot = path->slots[level + 1]; } if (!parent) return 1; left = read_node_slot(root, parent, pslot - 1); /* first, try to make some room in the middle buffer */ if (left) { u32 left_nr; btrfs_tree_lock(left); btrfs_set_lock_blocking(left); left_nr = btrfs_header_nritems(left); if (left_nr >= BTRFS_NODEPTRS_PER_BLOCK(root) - 1) { wret = 1; } else { ret = btrfs_cow_block(trans, root, left, parent, pslot - 1, &left); if (ret) wret = 1; else { wret = push_node_left(trans, root, left, mid, 0); } } if (wret < 0) ret = wret; if (wret == 0) { struct btrfs_disk_key disk_key; orig_slot += left_nr; btrfs_node_key(mid, &disk_key, 0); btrfs_set_node_key(parent, &disk_key, pslot); btrfs_mark_buffer_dirty(parent); if (btrfs_header_nritems(left) > orig_slot) { path->nodes[level] = left; path->slots[level + 1] -= 1; path->slots[level] = orig_slot; btrfs_tree_unlock(mid); free_extent_buffer(mid); } else { orig_slot -= btrfs_header_nritems(left); path->slots[level] = orig_slot; btrfs_tree_unlock(left); free_extent_buffer(left); } return 0; } btrfs_tree_unlock(left); free_extent_buffer(left); } right = read_node_slot(root, parent, pslot + 1); /* * then try to empty the right most buffer into the middle */ if (right) { u32 right_nr; btrfs_tree_lock(right); btrfs_set_lock_blocking(right); right_nr = btrfs_header_nritems(right); if (right_nr >= BTRFS_NODEPTRS_PER_BLOCK(root) - 1) { wret = 1; } else { ret = btrfs_cow_block(trans, root, right, parent, pslot + 1, &right); if (ret) wret = 1; else { wret = balance_node_right(trans, root, right, mid); } } if (wret < 0) ret = wret; if (wret == 0) { struct btrfs_disk_key disk_key; btrfs_node_key(right, &disk_key, 0); btrfs_set_node_key(parent, &disk_key, pslot + 1); btrfs_mark_buffer_dirty(parent); if (btrfs_header_nritems(mid) <= orig_slot) { path->nodes[level] = right; path->slots[level + 1] += 1; path->slots[level] = orig_slot - btrfs_header_nritems(mid); btrfs_tree_unlock(mid); free_extent_buffer(mid); } else { btrfs_tree_unlock(right); free_extent_buffer(right); } return 0; } btrfs_tree_unlock(right); free_extent_buffer(right); } return 1; } /* * readahead one full node of leaves, finding things that are close * to the block in 'slot', and triggering ra on them. */ static void reada_for_search(struct btrfs_root *root, struct btrfs_path *path, int level, int slot, u64 objectid) { struct extent_buffer *node; struct btrfs_disk_key disk_key; u32 nritems; u64 search; u64 target; u64 nread = 0; u64 gen; int direction = path->reada; struct extent_buffer *eb; u32 nr; u32 blocksize; u32 nscan = 0; if (level != 1) return; if (!path->nodes[level]) return; node = path->nodes[level]; search = btrfs_node_blockptr(node, slot); blocksize = btrfs_level_size(root, level - 1); eb = btrfs_find_tree_block(root, search, blocksize); if (eb) { free_extent_buffer(eb); return; } target = search; nritems = btrfs_header_nritems(node); nr = slot; while (1) { if (direction < 0) { if (nr == 0) break; nr--; } else if (direction > 0) { nr++; if (nr >= nritems) break; } if (path->reada < 0 && objectid) { btrfs_node_key(node, &disk_key, nr); if (btrfs_disk_key_objectid(&disk_key) != objectid) break; } search = btrfs_node_blockptr(node, nr); if ((search <= target && target - search <= 65536) || (search > target && search - target <= 65536)) { gen = btrfs_node_ptr_generation(node, nr); readahead_tree_block(root, search, blocksize, gen); nread += blocksize; } nscan++; if ((nread > 65536 || nscan > 32)) break; } } /* * returns -EAGAIN if it had to drop the path, or zero if everything was in * cache */ static noinline int reada_for_balance(struct btrfs_root *root, struct btrfs_path *path, int level) { int slot; int nritems; struct extent_buffer *parent; struct extent_buffer *eb; u64 gen; u64 block1 = 0; u64 block2 = 0; int ret = 0; int blocksize; parent = path->nodes[level + 1]; if (!parent) return 0; nritems = btrfs_header_nritems(parent); slot = path->slots[level + 1]; blocksize = btrfs_level_size(root, level); if (slot > 0) { block1 = btrfs_node_blockptr(parent, slot - 1); gen = btrfs_node_ptr_generation(parent, slot - 1); eb = btrfs_find_tree_block(root, block1, blocksize); if (eb && btrfs_buffer_uptodate(eb, gen)) block1 = 0; free_extent_buffer(eb); } if (slot + 1 < nritems) { block2 = btrfs_node_blockptr(parent, slot + 1); gen = btrfs_node_ptr_generation(parent, slot + 1); eb = btrfs_find_tree_block(root, block2, blocksize); if (eb && btrfs_buffer_uptodate(eb, gen)) block2 = 0; free_extent_buffer(eb); } if (block1 || block2) { ret = -EAGAIN; /* release the whole path */ btrfs_release_path(path); /* read the blocks */ if (block1) readahead_tree_block(root, block1, blocksize, 0); if (block2) readahead_tree_block(root, block2, blocksize, 0); if (block1) { eb = read_tree_block(root, block1, blocksize, 0); free_extent_buffer(eb); } if (block2) { eb = read_tree_block(root, block2, blocksize, 0); free_extent_buffer(eb); } } return ret; } /* * when we walk down the tree, it is usually safe to unlock the higher layers * in the tree. The exceptions are when our path goes through slot 0, because * operations on the tree might require changing key pointers higher up in the * tree. * * callers might also have set path->keep_locks, which tells this code to keep * the lock if the path points to the last slot in the block. This is part of * walking through the tree, and selecting the next slot in the higher block. * * lowest_unlock sets the lowest level in the tree we're allowed to unlock. so * if lowest_unlock is 1, level 0 won't be unlocked */ static noinline void unlock_up(struct btrfs_path *path, int level, int lowest_unlock) { int i; int skip_level = level; int no_skips = 0; struct extent_buffer *t; for (i = level; i < BTRFS_MAX_LEVEL; i++) { if (!path->nodes[i]) break; if (!path->locks[i]) break; if (!no_skips && path->slots[i] == 0) { skip_level = i + 1; continue; } if (!no_skips && path->keep_locks) { u32 nritems; t = path->nodes[i]; nritems = btrfs_header_nritems(t); if (nritems < 1 || path->slots[i] >= nritems - 1) { skip_level = i + 1; continue; } } if (skip_level < i && i >= lowest_unlock) no_skips = 1; t = path->nodes[i]; if (i >= lowest_unlock && i > skip_level && path->locks[i]) { btrfs_tree_unlock_rw(t, path->locks[i]); path->locks[i] = 0; } } } /* * This releases any locks held in the path starting at level and * going all the way up to the root. * * btrfs_search_slot will keep the lock held on higher nodes in a few * corner cases, such as COW of the block at slot zero in the node. This * ignores those rules, and it should only be called when there are no * more updates to be done higher up in the tree. */ noinline void btrfs_unlock_up_safe(struct btrfs_path *path, int level) { int i; if (path->keep_locks) return; for (i = level; i < BTRFS_MAX_LEVEL; i++) { if (!path->nodes[i]) continue; if (!path->locks[i]) continue; btrfs_tree_unlock_rw(path->nodes[i], path->locks[i]); path->locks[i] = 0; } } /* * helper function for btrfs_search_slot. The goal is to find a block * in cache without setting the path to blocking. If we find the block * we return zero and the path is unchanged. * * If we can't find the block, we set the path blocking and do some * reada. -EAGAIN is returned and the search must be repeated. */ static int read_block_for_search(struct btrfs_trans_handle *trans, struct btrfs_root *root, struct btrfs_path *p, struct extent_buffer **eb_ret, int level, int slot, struct btrfs_key *key) { u64 blocknr; u64 gen; u32 blocksize; struct extent_buffer *b = *eb_ret; struct extent_buffer *tmp; int ret; blocknr = btrfs_node_blockptr(b, slot); gen = btrfs_node_ptr_generation(b, slot); blocksize = btrfs_level_size(root, level - 1); tmp = btrfs_find_tree_block(root, blocknr, blocksize); if (tmp) { if (btrfs_buffer_uptodate(tmp, 0)) { if (btrfs_buffer_uptodate(tmp, gen)) { /* * we found an up to date block without * sleeping, return * right away */ *eb_ret = tmp; return 0; } /* the pages were up to date, but we failed * the generation number check. Do a full * read for the generation number that is correct. * We must do this without dropping locks so * we can trust our generation number */ free_extent_buffer(tmp); btrfs_set_path_blocking(p); tmp = read_tree_block(root, blocknr, blocksize, gen); if (tmp && btrfs_buffer_uptodate(tmp, gen)) { *eb_ret = tmp; return 0; } free_extent_buffer(tmp); btrfs_release_path(p); return -EIO; } } /* * reduce lock contention at high levels * of the btree by dropping locks before * we read. Don't release the lock on the current * level because we need to walk this node to figure * out which blocks to read. */ btrfs_unlock_up_safe(p, level + 1); btrfs_set_path_blocking(p); free_extent_buffer(tmp); if (p->reada) reada_for_search(root, p, level, slot, key->objectid); btrfs_release_path(p); ret = -EAGAIN; tmp = read_tree_block(root, blocknr, blocksize, 0); if (tmp) { /* * If the read above didn't mark this buffer up to date, * it will never end up being up to date. Set ret to EIO now * and give up so that our caller doesn't loop forever * on our EAGAINs. */ if (!btrfs_buffer_uptodate(tmp, 0)) ret = -EIO; free_extent_buffer(tmp); } return ret; } /* * helper function for btrfs_search_slot. This does all of the checks * for node-level blocks and does any balancing required based on * the ins_len. * * If no extra work was required, zero is returned. If we had to * drop the path, -EAGAIN is returned and btrfs_search_slot must * start over */ static int setup_nodes_for_search(struct btrfs_trans_handle *trans, struct btrfs_root *root, struct btrfs_path *p, struct extent_buffer *b, int level, int ins_len, int *write_lock_level) { int ret; if ((p->search_for_split || ins_len > 0) && btrfs_header_nritems(b) >= BTRFS_NODEPTRS_PER_BLOCK(root) - 3) { int sret; if (*write_lock_level < level + 1) { *write_lock_level = level + 1; btrfs_release_path(p); goto again; } sret = reada_for_balance(root, p, level); if (sret) goto again; btrfs_set_path_blocking(p); sret = split_node(trans, root, p, level); btrfs_clear_path_blocking(p, NULL, 0); BUG_ON(sret > 0); if (sret) { ret = sret; goto done; } b = p->nodes[level]; } else if (ins_len < 0 && btrfs_header_nritems(b) < BTRFS_NODEPTRS_PER_BLOCK(root) / 2) { int sret; if (*write_lock_level < level + 1) { *write_lock_level = level + 1; btrfs_release_path(p); goto again; } sret = reada_for_balance(root, p, level); if (sret) goto again; btrfs_set_path_blocking(p); sret = balance_level(trans, root, p, level); btrfs_clear_path_blocking(p, NULL, 0); if (sret) { ret = sret; goto done; } b = p->nodes[level]; if (!b) { btrfs_release_path(p); goto again; } BUG_ON(btrfs_header_nritems(b) == 1); } return 0; again: ret = -EAGAIN; done: return ret; } /* * look for key in the tree. path is filled in with nodes along the way * if key is found, we return zero and you can find the item in the leaf * level of the path (level 0) * * If the key isn't found, the path points to the slot where it should * be inserted, and 1 is returned. If there are other errors during the * search a negative error number is returned. * * if ins_len > 0, nodes and leaves will be split as we walk down the * tree. if ins_len < 0, nodes will be merged as we walk down the tree (if * possible) */ int btrfs_search_slot(struct btrfs_trans_handle *trans, struct btrfs_root *root, struct btrfs_key *key, struct btrfs_path *p, int ins_len, int cow) { struct extent_buffer *b; int slot; int ret; int err; int level; int lowest_unlock = 1; int root_lock; /* everything at write_lock_level or lower must be write locked */ int write_lock_level = 0; u8 lowest_level = 0; lowest_level = p->lowest_level; WARN_ON(lowest_level && ins_len > 0); WARN_ON(p->nodes[0] != NULL); if (ins_len < 0) { lowest_unlock = 2; /* when we are removing items, we might have to go up to level * two as we update tree pointers Make sure we keep write * for those levels as well */ write_lock_level = 2; } else if (ins_len > 0) { /* * for inserting items, make sure we have a write lock on * level 1 so we can update keys */ write_lock_level = 1; } if (!cow) write_lock_level = -1; if (cow && (p->keep_locks || p->lowest_level)) write_lock_level = BTRFS_MAX_LEVEL; again: /* * we try very hard to do read locks on the root */ root_lock = BTRFS_READ_LOCK; level = 0; if (p->search_commit_root) { /* * the commit roots are read only * so we always do read locks */ b = root->commit_root; extent_buffer_get(b); level = btrfs_header_level(b); if (!p->skip_locking) btrfs_tree_read_lock(b); } else { if (p->skip_locking) { b = btrfs_root_node(root); level = btrfs_header_level(b); } else { /* we don't know the level of the root node * until we actually have it read locked */ b = btrfs_read_lock_root_node(root); level = btrfs_header_level(b); if (level <= write_lock_level) { /* whoops, must trade for write lock */ btrfs_tree_read_unlock(b); free_extent_buffer(b); b = btrfs_lock_root_node(root); root_lock = BTRFS_WRITE_LOCK; /* the level might have changed, check again */ level = btrfs_header_level(b); } } } p->nodes[level] = b; if (!p->skip_locking) p->locks[level] = root_lock; while (b) { level = btrfs_header_level(b); /* * setup the path here so we can release it under lock * contention with the cow code */ if (cow) { /* * if we don't really need to cow this block * then we don't want to set the path blocking, * so we test it here */ if (!should_cow_block(trans, root, b)) goto cow_done; btrfs_set_path_blocking(p); /* * must have write locks on this node and the * parent */ if (level + 1 > write_lock_level) { write_lock_level = level + 1; btrfs_release_path(p); goto again; } err = btrfs_cow_block(trans, root, b, p->nodes[level + 1], p->slots[level + 1], &b); if (err) { ret = err; goto done; } } cow_done: BUG_ON(!cow && ins_len); p->nodes[level] = b; btrfs_clear_path_blocking(p, NULL, 0); /* * we have a lock on b and as long as we aren't changing * the tree, there is no way to for the items in b to change. * It is safe to drop the lock on our parent before we * go through the expensive btree search on b. * * If cow is true, then we might be changing slot zero, * which may require changing the parent. So, we can't * drop the lock until after we know which slot we're * operating on. */ if (!cow) btrfs_unlock_up_safe(p, level + 1); ret = bin_search(b, key, level, &slot); if (level != 0) { int dec = 0; if (ret && slot > 0) { dec = 1; slot -= 1; } p->slots[level] = slot; err = setup_nodes_for_search(trans, root, p, b, level, ins_len, &write_lock_level); if (err == -EAGAIN) goto again; if (err) { ret = err; goto done; } b = p->nodes[level]; slot = p->slots[level]; /* * slot 0 is special, if we change the key * we have to update the parent pointer * which means we must have a write lock * on the parent */ if (slot == 0 && cow && write_lock_level < level + 1) { write_lock_level = level + 1; btrfs_release_path(p); goto again; } unlock_up(p, level, lowest_unlock); if (level == lowest_level) { if (dec) p->slots[level]++; goto done; } err = read_block_for_search(trans, root, p, &b, level, slot, key); if (err == -EAGAIN) goto again; if (err) { ret = err; goto done; } if (!p->skip_locking) { level = btrfs_header_level(b); if (level <= write_lock_level) { err = btrfs_try_tree_write_lock(b); if (!err) { btrfs_set_path_blocking(p); btrfs_tree_lock(b); btrfs_clear_path_blocking(p, b, BTRFS_WRITE_LOCK); } p->locks[level] = BTRFS_WRITE_LOCK; } else { err = btrfs_try_tree_read_lock(b); if (!err) { btrfs_set_path_blocking(p); btrfs_tree_read_lock(b); btrfs_clear_path_blocking(p, b, BTRFS_READ_LOCK); } p->locks[level] = BTRFS_READ_LOCK; } p->nodes[level] = b; } } else { p->slots[level] = slot; if (ins_len > 0 && btrfs_leaf_free_space(root, b) < ins_len) { if (write_lock_level < 1) { write_lock_level = 1; btrfs_release_path(p); goto again; } btrfs_set_path_blocking(p); err = split_leaf(trans, root, key, p, ins_len, ret == 0); btrfs_clear_path_blocking(p, NULL, 0); BUG_ON(err > 0); if (err) { ret = err; goto done; } } if (!p->search_for_split) unlock_up(p, level, lowest_unlock); goto done; } } ret = 1; done: /* * we don't really know what they plan on doing with the path * from here on, so for now just mark it as blocking */ if (!p->leave_spinning) btrfs_set_path_blocking(p); if (ret < 0) btrfs_release_path(p); return ret; } /* * adjust the pointers going up the tree, starting at level * making sure the right key of each node is points to 'key'. * This is used after shifting pointers to the left, so it stops * fixing up pointers when a given leaf/node is not in slot 0 of the * higher levels * * If this fails to write a tree block, it returns -1, but continues * fixing up the blocks in ram so the tree is consistent. */ static int fixup_low_keys(struct btrfs_trans_handle *trans, struct btrfs_root *root, struct btrfs_path *path, struct btrfs_disk_key *key, int level) { int i; int ret = 0; struct extent_buffer *t; for (i = level; i < BTRFS_MAX_LEVEL; i++) { int tslot = path->slots[i]; if (!path->nodes[i]) break; t = path->nodes[i]; btrfs_set_node_key(t, key, tslot); btrfs_mark_buffer_dirty(path->nodes[i]); if (tslot != 0) break; } return ret; } /* * update item key. * * This function isn't completely safe. It's the caller's responsibility * that the new key won't break the order */ int btrfs_set_item_key_safe(struct btrfs_trans_handle *trans, struct btrfs_root *root, struct btrfs_path *path, struct btrfs_key *new_key) { struct btrfs_disk_key disk_key; struct extent_buffer *eb; int slot; eb = path->nodes[0]; slot = path->slots[0]; if (slot > 0) { btrfs_item_key(eb, &disk_key, slot - 1); if (comp_keys(&disk_key, new_key) >= 0) return -1; } if (slot < btrfs_header_nritems(eb) - 1) { btrfs_item_key(eb, &disk_key, slot + 1); if (comp_keys(&disk_key, new_key) <= 0) return -1; } btrfs_cpu_key_to_disk(&disk_key, new_key); btrfs_set_item_key(eb, &disk_key, slot); btrfs_mark_buffer_dirty(eb); if (slot == 0) fixup_low_keys(trans, root, path, &disk_key, 1); return 0; } /* * try to push data from one node into the next node left in the * tree. * * returns 0 if some ptrs were pushed left, < 0 if there was some horrible * error, and > 0 if there was no room in the left hand block. */ static int push_node_left(struct btrfs_trans_handle *trans, struct btrfs_root *root, struct extent_buffer *dst, struct extent_buffer *src, int empty) { int push_items = 0; int src_nritems; int dst_nritems; int ret = 0; src_nritems = btrfs_header_nritems(src); dst_nritems = btrfs_header_nritems(dst); push_items = BTRFS_NODEPTRS_PER_BLOCK(root) - dst_nritems; WARN_ON(btrfs_header_generation(src) != trans->transid); WARN_ON(btrfs_header_generation(dst) != trans->transid); if (!empty && src_nritems <= 8) return 1; if (push_items <= 0) return 1; if (empty) { push_items = min(src_nritems, push_items); if (push_items < src_nritems) { /* leave at least 8 pointers in the node if * we aren't going to empty it */ if (src_nritems - push_items < 8) { if (push_items <= 8) return 1; push_items -= 8; } } } else push_items = min(src_nritems - 8, push_items); copy_extent_buffer(dst, src, btrfs_node_key_ptr_offset(dst_nritems), btrfs_node_key_ptr_offset(0), push_items * sizeof(struct btrfs_key_ptr)); if (push_items < src_nritems) { memmove_extent_buffer(src, btrfs_node_key_ptr_offset(0), btrfs_node_key_ptr_offset(push_items), (src_nritems - push_items) * sizeof(struct btrfs_key_ptr)); } btrfs_set_header_nritems(src, src_nritems - push_items); btrfs_set_header_nritems(dst, dst_nritems + push_items); btrfs_mark_buffer_dirty(src); btrfs_mark_buffer_dirty(dst); return ret; } /* * try to push data from one node into the next node right in the * tree. * * returns 0 if some ptrs were pushed, < 0 if there was some horrible * error, and > 0 if there was no room in the right hand block. * * this will only push up to 1/2 the contents of the left node over */ static int balance_node_right(struct btrfs_trans_handle *trans, struct btrfs_root *root, struct extent_buffer *dst, struct extent_buffer *src) { int push_items = 0; int max_push; int src_nritems; int dst_nritems; int ret = 0; WARN_ON(btrfs_header_generation(src) != trans->transid); WARN_ON(btrfs_header_generation(dst) != trans->transid); src_nritems = btrfs_header_nritems(src); dst_nritems = btrfs_header_nritems(dst); push_items = BTRFS_NODEPTRS_PER_BLOCK(root) - dst_nritems; if (push_items <= 0) return 1; if (src_nritems < 4) return 1; max_push = src_nritems / 2 + 1; /* don't try to empty the node */ if (max_push >= src_nritems) return 1; if (max_push < push_items) push_items = max_push; memmove_extent_buffer(dst, btrfs_node_key_ptr_offset(push_items), btrfs_node_key_ptr_offset(0), (dst_nritems) * sizeof(struct btrfs_key_ptr)); copy_extent_buffer(dst, src, btrfs_node_key_ptr_offset(0), btrfs_node_key_ptr_offset(src_nritems - push_items), push_items * sizeof(struct btrfs_key_ptr)); btrfs_set_header_nritems(src, src_nritems - push_items); btrfs_set_header_nritems(dst, dst_nritems + push_items); btrfs_mark_buffer_dirty(src); btrfs_mark_buffer_dirty(dst); return ret; } /* * helper function to insert a new root level in the tree. * A new node is allocated, and a single item is inserted to * point to the existing root * * returns zero on success or < 0 on failure. */ static noinline int insert_new_root(struct btrfs_trans_handle *trans, struct btrfs_root *root, struct btrfs_path *path, int level) { u64 lower_gen; struct extent_buffer *lower; struct extent_buffer *c; struct extent_buffer *old; struct btrfs_disk_key lower_key; BUG_ON(path->nodes[level]); BUG_ON(path->nodes[level-1] != root->node); lower = path->nodes[level-1]; if (level == 1) btrfs_item_key(lower, &lower_key, 0); else btrfs_node_key(lower, &lower_key, 0); c = btrfs_alloc_free_block(trans, root, root->nodesize, 0, root->root_key.objectid, &lower_key, level, root->node->start, 0, 0); if (IS_ERR(c)) return PTR_ERR(c); root_add_used(root, root->nodesize); memset_extent_buffer(c, 0, 0, sizeof(struct btrfs_header)); btrfs_set_header_nritems(c, 1); btrfs_set_header_level(c, level); btrfs_set_header_bytenr(c, c->start); btrfs_set_header_generation(c, trans->transid); btrfs_set_header_backref_rev(c, BTRFS_MIXED_BACKREF_REV); btrfs_set_header_owner(c, root->root_key.objectid); write_extent_buffer(c, root->fs_info->fsid, (unsigned long)btrfs_header_fsid(c), BTRFS_FSID_SIZE); write_extent_buffer(c, root->fs_info->chunk_tree_uuid, (unsigned long)btrfs_header_chunk_tree_uuid(c), BTRFS_UUID_SIZE); btrfs_set_node_key(c, &lower_key, 0); btrfs_set_node_blockptr(c, 0, lower->start); lower_gen = btrfs_header_generation(lower); WARN_ON(lower_gen != trans->transid); btrfs_set_node_ptr_generation(c, 0, lower_gen); btrfs_mark_buffer_dirty(c); old = root->node; rcu_assign_pointer(root->node, c); /* the super has an extra ref to root->node */ free_extent_buffer(old); add_root_to_dirty_list(root); extent_buffer_get(c); path->nodes[level] = c; path->locks[level] = BTRFS_WRITE_LOCK; path->slots[level] = 0; return 0; } /* * worker function to insert a single pointer in a node. * the node should have enough room for the pointer already * * slot and level indicate where you want the key to go, and * blocknr is the block the key points to. * * returns zero on success and < 0 on any error */ static int insert_ptr(struct btrfs_trans_handle *trans, struct btrfs_root *root, struct btrfs_path *path, struct btrfs_disk_key *key, u64 bytenr, int slot, int level) { struct extent_buffer *lower; int nritems; BUG_ON(!path->nodes[level]); btrfs_assert_tree_locked(path->nodes[level]); lower = path->nodes[level]; nritems = btrfs_header_nritems(lower); BUG_ON(slot > nritems); if (nritems == BTRFS_NODEPTRS_PER_BLOCK(root)) BUG(); if (slot != nritems) { memmove_extent_buffer(lower, btrfs_node_key_ptr_offset(slot + 1), btrfs_node_key_ptr_offset(slot), (nritems - slot) * sizeof(struct btrfs_key_ptr)); } btrfs_set_node_key(lower, key, slot); btrfs_set_node_blockptr(lower, slot, bytenr); WARN_ON(trans->transid == 0); btrfs_set_node_ptr_generation(lower, slot, trans->transid); btrfs_set_header_nritems(lower, nritems + 1); btrfs_mark_buffer_dirty(lower); return 0; } /* * split the node at the specified level in path in two. * The path is corrected to point to the appropriate node after the split * * Before splitting this tries to make some room in the node by pushing * left and right, if either one works, it returns right away. * * returns 0 on success and < 0 on failure */ static noinline int split_node(struct btrfs_trans_handle *trans, struct btrfs_root *root, struct btrfs_path *path, int level) { struct extent_buffer *c; struct extent_buffer *split; struct btrfs_disk_key disk_key; int mid; int ret; int wret; u32 c_nritems; c = path->nodes[level]; WARN_ON(btrfs_header_generation(c) != trans->transid); if (c == root->node) { /* trying to split the root, lets make a new one */ ret = insert_new_root(trans, root, path, level + 1); if (ret) return ret; } else { ret = push_nodes_for_insert(trans, root, path, level); c = path->nodes[level]; if (!ret && btrfs_header_nritems(c) < BTRFS_NODEPTRS_PER_BLOCK(root) - 3) return 0; if (ret < 0) return ret; } c_nritems = btrfs_header_nritems(c); mid = (c_nritems + 1) / 2; btrfs_node_key(c, &disk_key, mid); split = btrfs_alloc_free_block(trans, root, root->nodesize, 0, root->root_key.objectid, &disk_key, level, c->start, 0, 0); if (IS_ERR(split)) return PTR_ERR(split); root_add_used(root, root->nodesize); memset_extent_buffer(split, 0, 0, sizeof(struct btrfs_header)); btrfs_set_header_level(split, btrfs_header_level(c)); btrfs_set_header_bytenr(split, split->start); btrfs_set_header_generation(split, trans->transid); btrfs_set_header_backref_rev(split, BTRFS_MIXED_BACKREF_REV); btrfs_set_header_owner(split, root->root_key.objectid); write_extent_buffer(split, root->fs_info->fsid, (unsigned long)btrfs_header_fsid(split), BTRFS_FSID_SIZE); write_extent_buffer(split, root->fs_info->chunk_tree_uuid, (unsigned long)btrfs_header_chunk_tree_uuid(split), BTRFS_UUID_SIZE); copy_extent_buffer(split, c, btrfs_node_key_ptr_offset(0), btrfs_node_key_ptr_offset(mid), (c_nritems - mid) * sizeof(struct btrfs_key_ptr)); btrfs_set_header_nritems(split, c_nritems - mid); btrfs_set_header_nritems(c, mid); ret = 0; btrfs_mark_buffer_dirty(c); btrfs_mark_buffer_dirty(split); wret = insert_ptr(trans, root, path, &disk_key, split->start, path->slots[level + 1] + 1, level + 1); if (wret) ret = wret; if (path->slots[level] >= mid) { path->slots[level] -= mid; btrfs_tree_unlock(c); free_extent_buffer(c); path->nodes[level] = split; path->slots[level + 1] += 1; } else { btrfs_tree_unlock(split); free_extent_buffer(split); } return ret; } /* * how many bytes are required to store the items in a leaf. start * and nr indicate which items in the leaf to check. This totals up the * space used both by the item structs and the item data */ static int leaf_space_used(struct extent_buffer *l, int start, int nr) { int data_len; int nritems = btrfs_header_nritems(l); int end = min(nritems, start + nr) - 1; if (!nr) return 0; data_len = btrfs_item_end_nr(l, start); data_len = data_len - btrfs_item_offset_nr(l, end); data_len += sizeof(struct btrfs_item) * nr; WARN_ON(data_len < 0); return data_len; } /* * The space between the end of the leaf items and * the start of the leaf data. IOW, how much room * the leaf has left for both items and data */ noinline int btrfs_leaf_free_space(struct btrfs_root *root, struct extent_buffer *leaf) { int nritems = btrfs_header_nritems(leaf); int ret; ret = BTRFS_LEAF_DATA_SIZE(root) - leaf_space_used(leaf, 0, nritems); if (ret < 0) { printk(KERN_CRIT "leaf free space ret %d, leaf data size %lu, " "used %d nritems %d\n", ret, (unsigned long) BTRFS_LEAF_DATA_SIZE(root), leaf_space_used(leaf, 0, nritems), nritems); } return ret; } /* * min slot controls the lowest index we're willing to push to the * right. We'll push up to and including min_slot, but no lower */ static noinline int __push_leaf_right(struct btrfs_trans_handle *trans, struct btrfs_root *root, struct btrfs_path *path, int data_size, int empty, struct extent_buffer *right, int free_space, u32 left_nritems, u32 min_slot) { struct extent_buffer *left = path->nodes[0]; struct extent_buffer *upper = path->nodes[1]; struct btrfs_disk_key disk_key; int slot; u32 i; int push_space = 0; int push_items = 0; struct btrfs_item *item; u32 nr; u32 right_nritems; u32 data_end; u32 this_item_size; if (empty) nr = 0; else nr = max_t(u32, 1, min_slot); if (path->slots[0] >= left_nritems) push_space += data_size; slot = path->slots[1]; i = left_nritems - 1; while (i >= nr) { item = btrfs_item_nr(left, i); if (!empty && push_items > 0) { if (path->slots[0] > i) break; if (path->slots[0] == i) { int space = btrfs_leaf_free_space(root, left); if (space + push_space * 2 > free_space) break; } } if (path->slots[0] == i) push_space += data_size; this_item_size = btrfs_item_size(left, item); if (this_item_size + sizeof(*item) + push_space > free_space) break; push_items++; push_space += this_item_size + sizeof(*item); if (i == 0) break; i--; } if (push_items == 0) goto out_unlock; if (!empty && push_items == left_nritems) WARN_ON(1); /* push left to right */ right_nritems = btrfs_header_nritems(right); push_space = btrfs_item_end_nr(left, left_nritems - push_items); push_space -= leaf_data_end(root, left); /* make room in the right data area */ data_end = leaf_data_end(root, right); memmove_extent_buffer(right, btrfs_leaf_data(right) + data_end - push_space, btrfs_leaf_data(right) + data_end, BTRFS_LEAF_DATA_SIZE(root) - data_end); /* copy from the left data area */ copy_extent_buffer(right, left, btrfs_leaf_data(right) + BTRFS_LEAF_DATA_SIZE(root) - push_space, btrfs_leaf_data(left) + leaf_data_end(root, left), push_space); memmove_extent_buffer(right, btrfs_item_nr_offset(push_items), btrfs_item_nr_offset(0), right_nritems * sizeof(struct btrfs_item)); /* copy the items from left to right */ copy_extent_buffer(right, left, btrfs_item_nr_offset(0), btrfs_item_nr_offset(left_nritems - push_items), push_items * sizeof(struct btrfs_item)); /* update the item pointers */ right_nritems += push_items; btrfs_set_header_nritems(right, right_nritems); push_space = BTRFS_LEAF_DATA_SIZE(root); for (i = 0; i < right_nritems; i++) { item = btrfs_item_nr(right, i); push_space -= btrfs_item_size(right, item); btrfs_set_item_offset(right, item, push_space); } left_nritems -= push_items; btrfs_set_header_nritems(left, left_nritems); if (left_nritems) btrfs_mark_buffer_dirty(left); else clean_tree_block(trans, root, left); btrfs_mark_buffer_dirty(right); btrfs_item_key(right, &disk_key, 0); btrfs_set_node_key(upper, &disk_key, slot + 1); btrfs_mark_buffer_dirty(upper); /* then fixup the leaf pointer in the path */ if (path->slots[0] >= left_nritems) { path->slots[0] -= left_nritems; if (btrfs_header_nritems(path->nodes[0]) == 0) clean_tree_block(trans, root, path->nodes[0]); btrfs_tree_unlock(path->nodes[0]); free_extent_buffer(path->nodes[0]); path->nodes[0] = right; path->slots[1] += 1; } else { btrfs_tree_unlock(right); free_extent_buffer(right); } return 0; out_unlock: btrfs_tree_unlock(right); free_extent_buffer(right); return 1; } /* * push some data in the path leaf to the right, trying to free up at * least data_size bytes. returns zero if the push worked, nonzero otherwise * * returns 1 if the push failed because the other node didn't have enough * room, 0 if everything worked out and < 0 if there were major errors. * * this will push starting from min_slot to the end of the leaf. It won't * push any slot lower than min_slot */ static int push_leaf_right(struct btrfs_trans_handle *trans, struct btrfs_root *root, struct btrfs_path *path, int min_data_size, int data_size, int empty, u32 min_slot) { struct extent_buffer *left = path->nodes[0]; struct extent_buffer *right; struct extent_buffer *upper; int slot; int free_space; u32 left_nritems; int ret; if (!path->nodes[1]) return 1; slot = path->slots[1]; upper = path->nodes[1]; if (slot >= btrfs_header_nritems(upper) - 1) return 1; btrfs_assert_tree_locked(path->nodes[1]); right = read_node_slot(root, upper, slot + 1); if (right == NULL) return 1; btrfs_tree_lock(right); btrfs_set_lock_blocking(right); free_space = btrfs_leaf_free_space(root, right); if (free_space < data_size) goto out_unlock; /* cow and double check */ ret = btrfs_cow_block(trans, root, right, upper, slot + 1, &right); if (ret) goto out_unlock; free_space = btrfs_leaf_free_space(root, right); if (free_space < data_size) goto out_unlock; left_nritems = btrfs_header_nritems(left); if (left_nritems == 0) goto out_unlock; return __push_leaf_right(trans, root, path, min_data_size, empty, right, free_space, left_nritems, min_slot); out_unlock: btrfs_tree_unlock(right); free_extent_buffer(right); return 1; } /* * push some data in the path leaf to the left, trying to free up at * least data_size bytes. returns zero if the push worked, nonzero otherwise * * max_slot can put a limit on how far into the leaf we'll push items. The * item at 'max_slot' won't be touched. Use (u32)-1 to make us do all the * items */ static noinline int __push_leaf_left(struct btrfs_trans_handle *trans, struct btrfs_root *root, struct btrfs_path *path, int data_size, int empty, struct extent_buffer *left, int free_space, u32 right_nritems, u32 max_slot) { struct btrfs_disk_key disk_key; struct extent_buffer *right = path->nodes[0]; int i; int push_space = 0; int push_items = 0; struct btrfs_item *item; u32 old_left_nritems; u32 nr; int ret = 0; int wret; u32 this_item_size; u32 old_left_item_size; if (empty) nr = min(right_nritems, max_slot); else nr = min(right_nritems - 1, max_slot); for (i = 0; i < nr; i++) { item = btrfs_item_nr(right, i); if (!empty && push_items > 0) { if (path->slots[0] < i) break; if (path->slots[0] == i) { int space = btrfs_leaf_free_space(root, right); if (space + push_space * 2 > free_space) break; } } if (path->slots[0] == i) push_space += data_size; this_item_size = btrfs_item_size(right, item); if (this_item_size + sizeof(*item) + push_space > free_space) break; push_items++; push_space += this_item_size + sizeof(*item); } if (push_items == 0) { ret = 1; goto out; } if (!empty && push_items == btrfs_header_nritems(right)) WARN_ON(1); /* push data from right to left */ copy_extent_buffer(left, right, btrfs_item_nr_offset(btrfs_header_nritems(left)), btrfs_item_nr_offset(0), push_items * sizeof(struct btrfs_item)); push_space = BTRFS_LEAF_DATA_SIZE(root) - btrfs_item_offset_nr(right, push_items - 1); copy_extent_buffer(left, right, btrfs_leaf_data(left) + leaf_data_end(root, left) - push_space, btrfs_leaf_data(right) + btrfs_item_offset_nr(right, push_items - 1), push_space); old_left_nritems = btrfs_header_nritems(left); BUG_ON(old_left_nritems <= 0); old_left_item_size = btrfs_item_offset_nr(left, old_left_nritems - 1); for (i = old_left_nritems; i < old_left_nritems + push_items; i++) { u32 ioff; item = btrfs_item_nr(left, i); ioff = btrfs_item_offset(left, item); btrfs_set_item_offset(left, item, ioff - (BTRFS_LEAF_DATA_SIZE(root) - old_left_item_size)); } btrfs_set_header_nritems(left, old_left_nritems + push_items); /* fixup right node */ if (push_items > right_nritems) { printk(KERN_CRIT "push items %d nr %u\n", push_items, right_nritems); WARN_ON(1); } if (push_items < right_nritems) { push_space = btrfs_item_offset_nr(right, push_items - 1) - leaf_data_end(root, right); memmove_extent_buffer(right, btrfs_leaf_data(right) + BTRFS_LEAF_DATA_SIZE(root) - push_space, btrfs_leaf_data(right) + leaf_data_end(root, right), push_space); memmove_extent_buffer(right, btrfs_item_nr_offset(0), btrfs_item_nr_offset(push_items), (btrfs_header_nritems(right) - push_items) * sizeof(struct btrfs_item)); } right_nritems -= push_items; btrfs_set_header_nritems(right, right_nritems); push_space = BTRFS_LEAF_DATA_SIZE(root); for (i = 0; i < right_nritems; i++) { item = btrfs_item_nr(right, i); push_space = push_space - btrfs_item_size(right, item); btrfs_set_item_offset(right, item, push_space); } btrfs_mark_buffer_dirty(left); if (right_nritems) btrfs_mark_buffer_dirty(right); else clean_tree_block(trans, root, right); btrfs_item_key(right, &disk_key, 0); wret = fixup_low_keys(trans, root, path, &disk_key, 1); if (wret) ret = wret; /* then fixup the leaf pointer in the path */ if (path->slots[0] < push_items) { path->slots[0] += old_left_nritems; btrfs_tree_unlock(path->nodes[0]); free_extent_buffer(path->nodes[0]); path->nodes[0] = left; path->slots[1] -= 1; } else { btrfs_tree_unlock(left); free_extent_buffer(left); path->slots[0] -= push_items; } BUG_ON(path->slots[0] < 0); return ret; out: btrfs_tree_unlock(left); free_extent_buffer(left); return ret; } /* * push some data in the path leaf to the left, trying to free up at * least data_size bytes. returns zero if the push worked, nonzero otherwise * * max_slot can put a limit on how far into the leaf we'll push items. The * item at 'max_slot' won't be touched. Use (u32)-1 to make us push all the * items */ static int push_leaf_left(struct btrfs_trans_handle *trans, struct btrfs_root *root, struct btrfs_path *path, int min_data_size, int data_size, int empty, u32 max_slot) { struct extent_buffer *right = path->nodes[0]; struct extent_buffer *left; int slot; int free_space; u32 right_nritems; int ret = 0; slot = path->slots[1]; if (slot == 0) return 1; if (!path->nodes[1]) return 1; right_nritems = btrfs_header_nritems(right); if (right_nritems == 0) return 1; btrfs_assert_tree_locked(path->nodes[1]); left = read_node_slot(root, path->nodes[1], slot - 1); if (left == NULL) return 1; btrfs_tree_lock(left); btrfs_set_lock_blocking(left); free_space = btrfs_leaf_free_space(root, left); if (free_space < data_size) { ret = 1; goto out; } /* cow and double check */ ret = btrfs_cow_block(trans, root, left, path->nodes[1], slot - 1, &left); if (ret) { /* we hit -ENOSPC, but it isn't fatal here */ ret = 1; goto out; } free_space = btrfs_leaf_free_space(root, left); if (free_space < data_size) { ret = 1; goto out; } return __push_leaf_left(trans, root, path, min_data_size, empty, left, free_space, right_nritems, max_slot); out: btrfs_tree_unlock(left); free_extent_buffer(left); return ret; } /* * split the path's leaf in two, making sure there is at least data_size * available for the resulting leaf level of the path. * * returns 0 if all went well and < 0 on failure. */ static noinline int copy_for_split(struct btrfs_trans_handle *trans, struct btrfs_root *root, struct btrfs_path *path, struct extent_buffer *l, struct extent_buffer *right, int slot, int mid, int nritems) { int data_copy_size; int rt_data_off; int i; int ret = 0; int wret; struct btrfs_disk_key disk_key; nritems = nritems - mid; btrfs_set_header_nritems(right, nritems); data_copy_size = btrfs_item_end_nr(l, mid) - leaf_data_end(root, l); copy_extent_buffer(right, l, btrfs_item_nr_offset(0), btrfs_item_nr_offset(mid), nritems * sizeof(struct btrfs_item)); copy_extent_buffer(right, l, btrfs_leaf_data(right) + BTRFS_LEAF_DATA_SIZE(root) - data_copy_size, btrfs_leaf_data(l) + leaf_data_end(root, l), data_copy_size); rt_data_off = BTRFS_LEAF_DATA_SIZE(root) - btrfs_item_end_nr(l, mid); for (i = 0; i < nritems; i++) { struct btrfs_item *item = btrfs_item_nr(right, i); u32 ioff; ioff = btrfs_item_offset(right, item); btrfs_set_item_offset(right, item, ioff + rt_data_off); } btrfs_set_header_nritems(l, mid); ret = 0; btrfs_item_key(right, &disk_key, 0); wret = insert_ptr(trans, root, path, &disk_key, right->start, path->slots[1] + 1, 1); if (wret) ret = wret; btrfs_mark_buffer_dirty(right); btrfs_mark_buffer_dirty(l); BUG_ON(path->slots[0] != slot); if (mid <= slot) { btrfs_tree_unlock(path->nodes[0]); free_extent_buffer(path->nodes[0]); path->nodes[0] = right; path->slots[0] -= mid; path->slots[1] += 1; } else { btrfs_tree_unlock(right); free_extent_buffer(right); } BUG_ON(path->slots[0] < 0); return ret; } /* * double splits happen when we need to insert a big item in the middle * of a leaf. A double split can leave us with 3 mostly empty leaves: * leaf: [ slots 0 - N] [ our target ] [ N + 1 - total in leaf ] * A B C * * We avoid this by trying to push the items on either side of our target * into the adjacent leaves. If all goes well we can avoid the double split * completely. */ static noinline int push_for_double_split(struct btrfs_trans_handle *trans, struct btrfs_root *root, struct btrfs_path *path, int data_size) { int ret; int progress = 0; int slot; u32 nritems; slot = path->slots[0]; /* * try to push all the items after our slot into the * right leaf */ ret = push_leaf_right(trans, root, path, 1, data_size, 0, slot); if (ret < 0) return ret; if (ret == 0) progress++; nritems = btrfs_header_nritems(path->nodes[0]); /* * our goal is to get our slot at the start or end of a leaf. If * we've done so we're done */ if (path->slots[0] == 0 || path->slots[0] == nritems) return 0; if (btrfs_leaf_free_space(root, path->nodes[0]) >= data_size) return 0; /* try to push all the items before our slot into the next leaf */ slot = path->slots[0]; ret = push_leaf_left(trans, root, path, 1, data_size, 0, slot); if (ret < 0) return ret; if (ret == 0) progress++; if (progress) return 0; return 1; } /* * split the path's leaf in two, making sure there is at least data_size * available for the resulting leaf level of the path. * * returns 0 if all went well and < 0 on failure. */ static noinline int split_leaf(struct btrfs_trans_handle *trans, struct btrfs_root *root, struct btrfs_key *ins_key, struct btrfs_path *path, int data_size, int extend) { struct btrfs_disk_key disk_key; struct extent_buffer *l; u32 nritems; int mid; int slot; struct extent_buffer *right; int ret = 0; int wret; int split; int num_doubles = 0; int tried_avoid_double = 0; l = path->nodes[0]; slot = path->slots[0]; if (extend && data_size + btrfs_item_size_nr(l, slot) + sizeof(struct btrfs_item) > BTRFS_LEAF_DATA_SIZE(root)) return -EOVERFLOW; /* first try to make some room by pushing left and right */ if (data_size) { wret = push_leaf_right(trans, root, path, data_size, data_size, 0, 0); if (wret < 0) return wret; if (wret) { wret = push_leaf_left(trans, root, path, data_size, data_size, 0, (u32)-1); if (wret < 0) return wret; } l = path->nodes[0]; /* did the pushes work? */ if (btrfs_leaf_free_space(root, l) >= data_size) return 0; } if (!path->nodes[1]) { ret = insert_new_root(trans, root, path, 1); if (ret) return ret; } again: split = 1; l = path->nodes[0]; slot = path->slots[0]; nritems = btrfs_header_nritems(l); mid = (nritems + 1) / 2; if (mid <= slot) { if (nritems == 1 || leaf_space_used(l, mid, nritems - mid) + data_size > BTRFS_LEAF_DATA_SIZE(root)) { if (slot >= nritems) { split = 0; } else { mid = slot; if (mid != nritems && leaf_space_used(l, mid, nritems - mid) + data_size > BTRFS_LEAF_DATA_SIZE(root)) { if (data_size && !tried_avoid_double) goto push_for_double; split = 2; } } } } else { if (leaf_space_used(l, 0, mid) + data_size > BTRFS_LEAF_DATA_SIZE(root)) { if (!extend && data_size && slot == 0) { split = 0; } else if ((extend || !data_size) && slot == 0) { mid = 1; } else { mid = slot; if (mid != nritems && leaf_space_used(l, mid, nritems - mid) + data_size > BTRFS_LEAF_DATA_SIZE(root)) { if (data_size && !tried_avoid_double) goto push_for_double; split = 2 ; } } } } if (split == 0) btrfs_cpu_key_to_disk(&disk_key, ins_key); else btrfs_item_key(l, &disk_key, mid); right = btrfs_alloc_free_block(trans, root, root->leafsize, 0, root->root_key.objectid, &disk_key, 0, l->start, 0, 0); if (IS_ERR(right)) return PTR_ERR(right); root_add_used(root, root->leafsize); memset_extent_buffer(right, 0, 0, sizeof(struct btrfs_header)); btrfs_set_header_bytenr(right, right->start); btrfs_set_header_generation(right, trans->transid); btrfs_set_header_backref_rev(right, BTRFS_MIXED_BACKREF_REV); btrfs_set_header_owner(right, root->root_key.objectid); btrfs_set_header_level(right, 0); write_extent_buffer(right, root->fs_info->fsid, (unsigned long)btrfs_header_fsid(right), BTRFS_FSID_SIZE); write_extent_buffer(right, root->fs_info->chunk_tree_uuid, (unsigned long)btrfs_header_chunk_tree_uuid(right), BTRFS_UUID_SIZE); if (split == 0) { if (mid <= slot) { btrfs_set_header_nritems(right, 0); wret = insert_ptr(trans, root, path, &disk_key, right->start, path->slots[1] + 1, 1); if (wret) ret = wret; btrfs_tree_unlock(path->nodes[0]); free_extent_buffer(path->nodes[0]); path->nodes[0] = right; path->slots[0] = 0; path->slots[1] += 1; } else { btrfs_set_header_nritems(right, 0); wret = insert_ptr(trans, root, path, &disk_key, right->start, path->slots[1], 1); if (wret) ret = wret; btrfs_tree_unlock(path->nodes[0]); free_extent_buffer(path->nodes[0]); path->nodes[0] = right; path->slots[0] = 0; if (path->slots[1] == 0) { wret = fixup_low_keys(trans, root, path, &disk_key, 1); if (wret) ret = wret; } } btrfs_mark_buffer_dirty(right); return ret; } ret = copy_for_split(trans, root, path, l, right, slot, mid, nritems); BUG_ON(ret); if (split == 2) { BUG_ON(num_doubles != 0); num_doubles++; goto again; } return ret; push_for_double: push_for_double_split(trans, root, path, data_size); tried_avoid_double = 1; if (btrfs_leaf_free_space(root, path->nodes[0]) >= data_size) return 0; goto again; } static noinline int setup_leaf_for_split(struct btrfs_trans_handle *trans, struct btrfs_root *root, struct btrfs_path *path, int ins_len) { struct btrfs_key key; struct extent_buffer *leaf; struct btrfs_file_extent_item *fi; u64 extent_len = 0; u32 item_size; int ret; leaf = path->nodes[0]; btrfs_item_key_to_cpu(leaf, &key, path->slots[0]); BUG_ON(key.type != BTRFS_EXTENT_DATA_KEY && key.type != BTRFS_EXTENT_CSUM_KEY); if (btrfs_leaf_free_space(root, leaf) >= ins_len) return 0; item_size = btrfs_item_size_nr(leaf, path->slots[0]); if (key.type == BTRFS_EXTENT_DATA_KEY) { fi = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_file_extent_item); extent_len = btrfs_file_extent_num_bytes(leaf, fi); } btrfs_release_path(path); path->keep_locks = 1; path->search_for_split = 1; ret = btrfs_search_slot(trans, root, &key, path, 0, 1); path->search_for_split = 0; if (ret < 0) goto err; ret = -EAGAIN; leaf = path->nodes[0]; /* if our item isn't there or got smaller, return now */ if (ret > 0 || item_size != btrfs_item_size_nr(leaf, path->slots[0])) goto err; /* the leaf has changed, it now has room. return now */ if (btrfs_leaf_free_space(root, path->nodes[0]) >= ins_len) goto err; if (key.type == BTRFS_EXTENT_DATA_KEY) { fi = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_file_extent_item); if (extent_len != btrfs_file_extent_num_bytes(leaf, fi)) goto err; } btrfs_set_path_blocking(path); ret = split_leaf(trans, root, &key, path, ins_len, 1); if (ret) goto err; path->keep_locks = 0; btrfs_unlock_up_safe(path, 1); return 0; err: path->keep_locks = 0; return ret; } static noinline int split_item(struct btrfs_trans_handle *trans, struct btrfs_root *root, struct btrfs_path *path, struct btrfs_key *new_key, unsigned long split_offset) { struct extent_buffer *leaf; struct btrfs_item *item; struct btrfs_item *new_item; int slot; char *buf; u32 nritems; u32 item_size; u32 orig_offset; struct btrfs_disk_key disk_key; leaf = path->nodes[0]; BUG_ON(btrfs_leaf_free_space(root, leaf) < sizeof(struct btrfs_item)); btrfs_set_path_blocking(path); item = btrfs_item_nr(leaf, path->slots[0]); orig_offset = btrfs_item_offset(leaf, item); item_size = btrfs_item_size(leaf, item); buf = kmalloc(item_size, GFP_NOFS); if (!buf) return -ENOMEM; read_extent_buffer(leaf, buf, btrfs_item_ptr_offset(leaf, path->slots[0]), item_size); slot = path->slots[0] + 1; nritems = btrfs_header_nritems(leaf); if (slot != nritems) { /* shift the items */ memmove_extent_buffer(leaf, btrfs_item_nr_offset(slot + 1), btrfs_item_nr_offset(slot), (nritems - slot) * sizeof(struct btrfs_item)); } btrfs_cpu_key_to_disk(&disk_key, new_key); btrfs_set_item_key(leaf, &disk_key, slot); new_item = btrfs_item_nr(leaf, slot); btrfs_set_item_offset(leaf, new_item, orig_offset); btrfs_set_item_size(leaf, new_item, item_size - split_offset); btrfs_set_item_offset(leaf, item, orig_offset + item_size - split_offset); btrfs_set_item_size(leaf, item, split_offset); btrfs_set_header_nritems(leaf, nritems + 1); /* write the data for the start of the original item */ write_extent_buffer(leaf, buf, btrfs_item_ptr_offset(leaf, path->slots[0]), split_offset); /* write the data for the new item */ write_extent_buffer(leaf, buf + split_offset, btrfs_item_ptr_offset(leaf, slot), item_size - split_offset); btrfs_mark_buffer_dirty(leaf); BUG_ON(btrfs_leaf_free_space(root, leaf) < 0); kfree(buf); return 0; } /* * This function splits a single item into two items, * giving 'new_key' to the new item and splitting the * old one at split_offset (from the start of the item). * * The path may be released by this operation. After * the split, the path is pointing to the old item. The * new item is going to be in the same node as the old one. * * Note, the item being split must be smaller enough to live alone on * a tree block with room for one extra struct btrfs_item * * This allows us to split the item in place, keeping a lock on the * leaf the entire time. */ int btrfs_split_item(struct btrfs_trans_handle *trans, struct btrfs_root *root, struct btrfs_path *path, struct btrfs_key *new_key, unsigned long split_offset) { int ret; ret = setup_leaf_for_split(trans, root, path, sizeof(struct btrfs_item)); if (ret) return ret; ret = split_item(trans, root, path, new_key, split_offset); return ret; } /* * This function duplicate a item, giving 'new_key' to the new item. * It guarantees both items live in the same tree leaf and the new item * is contiguous with the original item. * * This allows us to split file extent in place, keeping a lock on the * leaf the entire time. */ int btrfs_duplicate_item(struct btrfs_trans_handle *trans, struct btrfs_root *root, struct btrfs_path *path, struct btrfs_key *new_key) { struct extent_buffer *leaf; int ret; u32 item_size; leaf = path->nodes[0]; item_size = btrfs_item_size_nr(leaf, path->slots[0]); ret = setup_leaf_for_split(trans, root, path, item_size + sizeof(struct btrfs_item)); if (ret) return ret; path->slots[0]++; ret = setup_items_for_insert(trans, root, path, new_key, &item_size, item_size, item_size + sizeof(struct btrfs_item), 1); BUG_ON(ret); leaf = path->nodes[0]; memcpy_extent_buffer(leaf, btrfs_item_ptr_offset(leaf, path->slots[0]), btrfs_item_ptr_offset(leaf, path->slots[0] - 1), item_size); return 0; } /* * make the item pointed to by the path smaller. new_size indicates * how small to make it, and from_end tells us if we just chop bytes * off the end of the item or if we shift the item to chop bytes off * the front. */ int btrfs_truncate_item(struct btrfs_trans_handle *trans, struct btrfs_root *root, struct btrfs_path *path, u32 new_size, int from_end) { int slot; struct extent_buffer *leaf; struct btrfs_item *item; u32 nritems; unsigned int data_end; unsigned int old_data_start; unsigned int old_size; unsigned int size_diff; int i; leaf = path->nodes[0]; slot = path->slots[0]; old_size = btrfs_item_size_nr(leaf, slot); if (old_size == new_size) return 0; nritems = btrfs_header_nritems(leaf); data_end = leaf_data_end(root, leaf); old_data_start = btrfs_item_offset_nr(leaf, slot); size_diff = old_size - new_size; BUG_ON(slot < 0); BUG_ON(slot >= nritems); /* * item0..itemN ... dataN.offset..dataN.size .. data0.size */ /* first correct the data pointers */ for (i = slot; i < nritems; i++) { u32 ioff; item = btrfs_item_nr(leaf, i); ioff = btrfs_item_offset(leaf, item); btrfs_set_item_offset(leaf, item, ioff + size_diff); } /* shift the data */ if (from_end) { memmove_extent_buffer(leaf, btrfs_leaf_data(leaf) + data_end + size_diff, btrfs_leaf_data(leaf) + data_end, old_data_start + new_size - data_end); } else { struct btrfs_disk_key disk_key; u64 offset; btrfs_item_key(leaf, &disk_key, slot); if (btrfs_disk_key_type(&disk_key) == BTRFS_EXTENT_DATA_KEY) { unsigned long ptr; struct btrfs_file_extent_item *fi; fi = btrfs_item_ptr(leaf, slot, struct btrfs_file_extent_item); fi = (struct btrfs_file_extent_item *)( (unsigned long)fi - size_diff); if (btrfs_file_extent_type(leaf, fi) == BTRFS_FILE_EXTENT_INLINE) { ptr = btrfs_item_ptr_offset(leaf, slot); memmove_extent_buffer(leaf, ptr, (unsigned long)fi, offsetof(struct btrfs_file_extent_item, disk_bytenr)); } } memmove_extent_buffer(leaf, btrfs_leaf_data(leaf) + data_end + size_diff, btrfs_leaf_data(leaf) + data_end, old_data_start - data_end); offset = btrfs_disk_key_offset(&disk_key); btrfs_set_disk_key_offset(&disk_key, offset + size_diff); btrfs_set_item_key(leaf, &disk_key, slot); if (slot == 0) fixup_low_keys(trans, root, path, &disk_key, 1); } item = btrfs_item_nr(leaf, slot); btrfs_set_item_size(leaf, item, new_size); btrfs_mark_buffer_dirty(leaf); if (btrfs_leaf_free_space(root, leaf) < 0) { btrfs_print_leaf(root, leaf); BUG(); } return 0; } /* * make the item pointed to by the path bigger, data_size is the new size. */ int btrfs_extend_item(struct btrfs_trans_handle *trans, struct btrfs_root *root, struct btrfs_path *path, u32 data_size) { int slot; struct extent_buffer *leaf; struct btrfs_item *item; u32 nritems; unsigned int data_end; unsigned int old_data; unsigned int old_size; int i; leaf = path->nodes[0]; nritems = btrfs_header_nritems(leaf); data_end = leaf_data_end(root, leaf); if (btrfs_leaf_free_space(root, leaf) < data_size) { btrfs_print_leaf(root, leaf); BUG(); } slot = path->slots[0]; old_data = btrfs_item_end_nr(leaf, slot); BUG_ON(slot < 0); if (slot >= nritems) { btrfs_print_leaf(root, leaf); printk(KERN_CRIT "slot %d too large, nritems %d\n", slot, nritems); BUG_ON(1); } /* * item0..itemN ... dataN.offset..dataN.size .. data0.size */ /* first correct the data pointers */ for (i = slot; i < nritems; i++) { u32 ioff; item = btrfs_item_nr(leaf, i); ioff = btrfs_item_offset(leaf, item); btrfs_set_item_offset(leaf, item, ioff - data_size); } /* shift the data */ memmove_extent_buffer(leaf, btrfs_leaf_data(leaf) + data_end - data_size, btrfs_leaf_data(leaf) + data_end, old_data - data_end); data_end = old_data; old_size = btrfs_item_size_nr(leaf, slot); item = btrfs_item_nr(leaf, slot); btrfs_set_item_size(leaf, item, old_size + data_size); btrfs_mark_buffer_dirty(leaf); if (btrfs_leaf_free_space(root, leaf) < 0) { btrfs_print_leaf(root, leaf); BUG(); } return 0; } /* * Given a key and some data, insert items into the tree. * This does all the path init required, making room in the tree if needed. * Returns the number of keys that were inserted. */ int btrfs_insert_some_items(struct btrfs_trans_handle *trans, struct btrfs_root *root, struct btrfs_path *path, struct btrfs_key *cpu_key, u32 *data_size, int nr) { struct extent_buffer *leaf; struct btrfs_item *item; int ret = 0; int slot; int i; u32 nritems; u32 total_data = 0; u32 total_size = 0; unsigned int data_end; struct btrfs_disk_key disk_key; struct btrfs_key found_key; for (i = 0; i < nr; i++) { if (total_size + data_size[i] + sizeof(struct btrfs_item) > BTRFS_LEAF_DATA_SIZE(root)) { break; nr = i; } total_data += data_size[i]; total_size += data_size[i] + sizeof(struct btrfs_item); } BUG_ON(nr == 0); ret = btrfs_search_slot(trans, root, cpu_key, path, total_size, 1); if (ret == 0) return -EEXIST; if (ret < 0) goto out; leaf = path->nodes[0]; nritems = btrfs_header_nritems(leaf); data_end = leaf_data_end(root, leaf); if (btrfs_leaf_free_space(root, leaf) < total_size) { for (i = nr; i >= 0; i--) { total_data -= data_size[i]; total_size -= data_size[i] + sizeof(struct btrfs_item); if (total_size < btrfs_leaf_free_space(root, leaf)) break; } nr = i; } slot = path->slots[0]; BUG_ON(slot < 0); if (slot != nritems) { unsigned int old_data = btrfs_item_end_nr(leaf, slot); item = btrfs_item_nr(leaf, slot); btrfs_item_key_to_cpu(leaf, &found_key, slot); /* figure out how many keys we can insert in here */ total_data = data_size[0]; for (i = 1; i < nr; i++) { if (btrfs_comp_cpu_keys(&found_key, cpu_key + i) <= 0) break; total_data += data_size[i]; } nr = i; if (old_data < data_end) { btrfs_print_leaf(root, leaf); printk(KERN_CRIT "slot %d old_data %d data_end %d\n", slot, old_data, data_end); BUG_ON(1); } /* * item0..itemN ... dataN.offset..dataN.size .. data0.size */ /* first correct the data pointers */ for (i = slot; i < nritems; i++) { u32 ioff; item = btrfs_item_nr(leaf, i); ioff = btrfs_item_offset(leaf, item); btrfs_set_item_offset(leaf, item, ioff - total_data); } /* shift the items */ memmove_extent_buffer(leaf, btrfs_item_nr_offset(slot + nr), btrfs_item_nr_offset(slot), (nritems - slot) * sizeof(struct btrfs_item)); /* shift the data */ memmove_extent_buffer(leaf, btrfs_leaf_data(leaf) + data_end - total_data, btrfs_leaf_data(leaf) + data_end, old_data - data_end); data_end = old_data; } else { /* * this sucks but it has to be done, if we are inserting at * the end of the leaf only insert 1 of the items, since we * have no way of knowing whats on the next leaf and we'd have * to drop our current locks to figure it out */ nr = 1; } /* setup the item for the new data */ for (i = 0; i < nr; i++) { btrfs_cpu_key_to_disk(&disk_key, cpu_key + i); btrfs_set_item_key(leaf, &disk_key, slot + i); item = btrfs_item_nr(leaf, slot + i); btrfs_set_item_offset(leaf, item, data_end - data_size[i]); data_end -= data_size[i]; btrfs_set_item_size(leaf, item, data_size[i]); } btrfs_set_header_nritems(leaf, nritems + nr); btrfs_mark_buffer_dirty(leaf); ret = 0; if (slot == 0) { btrfs_cpu_key_to_disk(&disk_key, cpu_key); ret = fixup_low_keys(trans, root, path, &disk_key, 1); } if (btrfs_leaf_free_space(root, leaf) < 0) { btrfs_print_leaf(root, leaf); BUG(); } out: if (!ret) ret = nr; return ret; } /* * this is a helper for btrfs_insert_empty_items, the main goal here is * to save stack depth by doing the bulk of the work in a function * that doesn't call btrfs_search_slot */ int setup_items_for_insert(struct btrfs_trans_handle *trans, struct btrfs_root *root, struct btrfs_path *path, struct btrfs_key *cpu_key, u32 *data_size, u32 total_data, u32 total_size, int nr) { struct btrfs_item *item; int i; u32 nritems; unsigned int data_end; struct btrfs_disk_key disk_key; int ret; struct extent_buffer *leaf; int slot; leaf = path->nodes[0]; slot = path->slots[0]; nritems = btrfs_header_nritems(leaf); data_end = leaf_data_end(root, leaf); if (btrfs_leaf_free_space(root, leaf) < total_size) { btrfs_print_leaf(root, leaf); printk(KERN_CRIT "not enough freespace need %u have %d\n", total_size, btrfs_leaf_free_space(root, leaf)); BUG(); } if (slot != nritems) { unsigned int old_data = btrfs_item_end_nr(leaf, slot); if (old_data < data_end) { btrfs_print_leaf(root, leaf); printk(KERN_CRIT "slot %d old_data %d data_end %d\n", slot, old_data, data_end); BUG_ON(1); } /* * item0..itemN ... dataN.offset..dataN.size .. data0.size */ /* first correct the data pointers */ for (i = slot; i < nritems; i++) { u32 ioff; item = btrfs_item_nr(leaf, i); ioff = btrfs_item_offset(leaf, item); btrfs_set_item_offset(leaf, item, ioff - total_data); } /* shift the items */ memmove_extent_buffer(leaf, btrfs_item_nr_offset(slot + nr), btrfs_item_nr_offset(slot), (nritems - slot) * sizeof(struct btrfs_item)); /* shift the data */ memmove_extent_buffer(leaf, btrfs_leaf_data(leaf) + data_end - total_data, btrfs_leaf_data(leaf) + data_end, old_data - data_end); data_end = old_data; } /* setup the item for the new data */ for (i = 0; i < nr; i++) { btrfs_cpu_key_to_disk(&disk_key, cpu_key + i); btrfs_set_item_key(leaf, &disk_key, slot + i); item = btrfs_item_nr(leaf, slot + i); btrfs_set_item_offset(leaf, item, data_end - data_size[i]); data_end -= data_size[i]; btrfs_set_item_size(leaf, item, data_size[i]); } btrfs_set_header_nritems(leaf, nritems + nr); ret = 0; if (slot == 0) { btrfs_cpu_key_to_disk(&disk_key, cpu_key); ret = fixup_low_keys(trans, root, path, &disk_key, 1); } btrfs_unlock_up_safe(path, 1); btrfs_mark_buffer_dirty(leaf); if (btrfs_leaf_free_space(root, leaf) < 0) { btrfs_print_leaf(root, leaf); BUG(); } return ret; } /* * Given a key and some data, insert items into the tree. * This does all the path init required, making room in the tree if needed. */ int btrfs_insert_empty_items(struct btrfs_trans_handle *trans, struct btrfs_root *root, struct btrfs_path *path, struct btrfs_key *cpu_key, u32 *data_size, int nr) { int ret = 0; int slot; int i; u32 total_size = 0; u32 total_data = 0; for (i = 0; i < nr; i++) total_data += data_size[i]; total_size = total_data + (nr * sizeof(struct btrfs_item)); ret = btrfs_search_slot(trans, root, cpu_key, path, total_size, 1); if (ret == 0) return -EEXIST; if (ret < 0) goto out; slot = path->slots[0]; BUG_ON(slot < 0); ret = setup_items_for_insert(trans, root, path, cpu_key, data_size, total_data, total_size, nr); out: return ret; } /* * Given a key and some data, insert an item into the tree. * This does all the path init required, making room in the tree if needed. */ int btrfs_insert_item(struct btrfs_trans_handle *trans, struct btrfs_root *root, struct btrfs_key *cpu_key, void *data, u32 data_size) { int ret = 0; struct btrfs_path *path; struct extent_buffer *leaf; unsigned long ptr; path = btrfs_alloc_path(); if (!path) return -ENOMEM; ret = btrfs_insert_empty_item(trans, root, path, cpu_key, data_size); if (!ret) { leaf = path->nodes[0]; ptr = btrfs_item_ptr_offset(leaf, path->slots[0]); write_extent_buffer(leaf, data, ptr, data_size); btrfs_mark_buffer_dirty(leaf); } btrfs_free_path(path); return ret; } /* * delete the pointer from a given node. * * the tree should have been previously balanced so the deletion does not * empty a node. */ static int del_ptr(struct btrfs_trans_handle *trans, struct btrfs_root *root, struct btrfs_path *path, int level, int slot) { struct extent_buffer *parent = path->nodes[level]; u32 nritems; int ret = 0; int wret; nritems = btrfs_header_nritems(parent); if (slot != nritems - 1) { memmove_extent_buffer(parent, btrfs_node_key_ptr_offset(slot), btrfs_node_key_ptr_offset(slot + 1), sizeof(struct btrfs_key_ptr) * (nritems - slot - 1)); } nritems--; btrfs_set_header_nritems(parent, nritems); if (nritems == 0 && parent == root->node) { BUG_ON(btrfs_header_level(root->node) != 1); /* just turn the root into a leaf and break */ btrfs_set_header_level(root->node, 0); } else if (slot == 0) { struct btrfs_disk_key disk_key; btrfs_node_key(parent, &disk_key, 0); wret = fixup_low_keys(trans, root, path, &disk_key, level + 1); if (wret) ret = wret; } btrfs_mark_buffer_dirty(parent); return ret; } /* * a helper function to delete the leaf pointed to by path->slots[1] and * path->nodes[1]. * * This deletes the pointer in path->nodes[1] and frees the leaf * block extent. zero is returned if it all worked out, < 0 otherwise. * * The path must have already been setup for deleting the leaf, including * all the proper balancing. path->nodes[1] must be locked. */ static noinline int btrfs_del_leaf(struct btrfs_trans_handle *trans, struct btrfs_root *root, struct btrfs_path *path, struct extent_buffer *leaf) { int ret; WARN_ON(btrfs_header_generation(leaf) != trans->transid); ret = del_ptr(trans, root, path, 1, path->slots[1]); if (ret) return ret; /* * btrfs_free_extent is expensive, we want to make sure we * aren't holding any locks when we call it */ btrfs_unlock_up_safe(path, 0); root_sub_used(root, leaf->len); btrfs_free_tree_block(trans, root, leaf, 0, 1, 0); return 0; } /* * delete the item at the leaf level in path. If that empties * the leaf, remove it from the tree */ int btrfs_del_items(struct btrfs_trans_handle *trans, struct btrfs_root *root, struct btrfs_path *path, int slot, int nr) { struct extent_buffer *leaf; struct btrfs_item *item; int last_off; int dsize = 0; int ret = 0; int wret; int i; u32 nritems; leaf = path->nodes[0]; last_off = btrfs_item_offset_nr(leaf, slot + nr - 1); for (i = 0; i < nr; i++) dsize += btrfs_item_size_nr(leaf, slot + i); nritems = btrfs_header_nritems(leaf); if (slot + nr != nritems) { int data_end = leaf_data_end(root, leaf); memmove_extent_buffer(leaf, btrfs_leaf_data(leaf) + data_end + dsize, btrfs_leaf_data(leaf) + data_end, last_off - data_end); for (i = slot + nr; i < nritems; i++) { u32 ioff; item = btrfs_item_nr(leaf, i); ioff = btrfs_item_offset(leaf, item); btrfs_set_item_offset(leaf, item, ioff + dsize); } memmove_extent_buffer(leaf, btrfs_item_nr_offset(slot), btrfs_item_nr_offset(slot + nr), sizeof(struct btrfs_item) * (nritems - slot - nr)); } btrfs_set_header_nritems(leaf, nritems - nr); nritems -= nr; /* delete the leaf if we've emptied it */ if (nritems == 0) { if (leaf == root->node) { btrfs_set_header_level(leaf, 0); } else { btrfs_set_path_blocking(path); clean_tree_block(trans, root, leaf); ret = btrfs_del_leaf(trans, root, path, leaf); BUG_ON(ret); } } else { int used = leaf_space_used(leaf, 0, nritems); if (slot == 0) { struct btrfs_disk_key disk_key; btrfs_item_key(leaf, &disk_key, 0); wret = fixup_low_keys(trans, root, path, &disk_key, 1); if (wret) ret = wret; } /* delete the leaf if it is mostly empty */ if (used < BTRFS_LEAF_DATA_SIZE(root) / 3) { /* push_leaf_left fixes the path. * make sure the path still points to our leaf * for possible call to del_ptr below */ slot = path->slots[1]; extent_buffer_get(leaf); btrfs_set_path_blocking(path); wret = push_leaf_left(trans, root, path, 1, 1, 1, (u32)-1); if (wret < 0 && wret != -ENOSPC) ret = wret; if (path->nodes[0] == leaf && btrfs_header_nritems(leaf)) { wret = push_leaf_right(trans, root, path, 1, 1, 1, 0); if (wret < 0 && wret != -ENOSPC) ret = wret; } if (btrfs_header_nritems(leaf) == 0) { path->slots[1] = slot; ret = btrfs_del_leaf(trans, root, path, leaf); BUG_ON(ret); free_extent_buffer(leaf); } else { /* if we're still in the path, make sure * we're dirty. Otherwise, one of the * push_leaf functions must have already * dirtied this buffer */ if (path->nodes[0] == leaf) btrfs_mark_buffer_dirty(leaf); free_extent_buffer(leaf); } } else { btrfs_mark_buffer_dirty(leaf); } } return ret; } /* * search the tree again to find a leaf with lesser keys * returns 0 if it found something or 1 if there are no lesser leaves. * returns < 0 on io errors. * * This may release the path, and so you may lose any locks held at the * time you call it. */ int btrfs_prev_leaf(struct btrfs_root *root, struct btrfs_path *path) { struct btrfs_key key; struct btrfs_disk_key found_key; int ret; btrfs_item_key_to_cpu(path->nodes[0], &key, 0); if (key.offset > 0) key.offset--; else if (key.type > 0) key.type--; else if (key.objectid > 0) key.objectid--; else return 1; btrfs_release_path(path); ret = btrfs_search_slot(NULL, root, &key, path, 0, 0); if (ret < 0) return ret; btrfs_item_key(path->nodes[0], &found_key, 0); ret = comp_keys(&found_key, &key); if (ret < 0) return 0; return 1; } /* * A helper function to walk down the tree starting at min_key, and looking * for nodes or leaves that are either in cache or have a minimum * transaction id. This is used by the btree defrag code, and tree logging * * This does not cow, but it does stuff the starting key it finds back * into min_key, so you can call btrfs_search_slot with cow=1 on the * key and get a writable path. * * This does lock as it descends, and path->keep_locks should be set * to 1 by the caller. * * This honors path->lowest_level to prevent descent past a given level * of the tree. * * min_trans indicates the oldest transaction that you are interested * in walking through. Any nodes or leaves older than min_trans are * skipped over (without reading them). * * returns zero if something useful was found, < 0 on error and 1 if there * was nothing in the tree that matched the search criteria. */ int btrfs_search_forward(struct btrfs_root *root, struct btrfs_key *min_key, struct btrfs_key *max_key, struct btrfs_path *path, int cache_only, u64 min_trans) { struct extent_buffer *cur; struct btrfs_key found_key; int slot; int sret; u32 nritems; int level; int ret = 1; WARN_ON(!path->keep_locks); again: cur = btrfs_read_lock_root_node(root); level = btrfs_header_level(cur); WARN_ON(path->nodes[level]); path->nodes[level] = cur; path->locks[level] = BTRFS_READ_LOCK; if (btrfs_header_generation(cur) < min_trans) { ret = 1; goto out; } while (1) { nritems = btrfs_header_nritems(cur); level = btrfs_header_level(cur); sret = bin_search(cur, min_key, level, &slot); /* at the lowest level, we're done, setup the path and exit */ if (level == path->lowest_level) { if (slot >= nritems) goto find_next_key; ret = 0; path->slots[level] = slot; btrfs_item_key_to_cpu(cur, &found_key, slot); goto out; } if (sret && slot > 0) slot--; /* * check this node pointer against the cache_only and * min_trans parameters. If it isn't in cache or is too * old, skip to the next one. */ while (slot < nritems) { u64 blockptr; u64 gen; struct extent_buffer *tmp; struct btrfs_disk_key disk_key; blockptr = btrfs_node_blockptr(cur, slot); gen = btrfs_node_ptr_generation(cur, slot); if (gen < min_trans) { slot++; continue; } if (!cache_only) break; if (max_key) { btrfs_node_key(cur, &disk_key, slot); if (comp_keys(&disk_key, max_key) >= 0) { ret = 1; goto out; } } tmp = btrfs_find_tree_block(root, blockptr, btrfs_level_size(root, level - 1)); if (tmp && btrfs_buffer_uptodate(tmp, gen)) { free_extent_buffer(tmp); break; } if (tmp) free_extent_buffer(tmp); slot++; } find_next_key: /* * we didn't find a candidate key in this node, walk forward * and find another one */ if (slot >= nritems) { path->slots[level] = slot; btrfs_set_path_blocking(path); sret = btrfs_find_next_key(root, path, min_key, level, cache_only, min_trans); if (sret == 0) { btrfs_release_path(path); goto again; } else { goto out; } } /* save our key for returning back */ btrfs_node_key_to_cpu(cur, &found_key, slot); path->slots[level] = slot; if (level == path->lowest_level) { ret = 0; unlock_up(path, level, 1); goto out; } btrfs_set_path_blocking(path); cur = read_node_slot(root, cur, slot); BUG_ON(!cur); btrfs_tree_read_lock(cur); path->locks[level - 1] = BTRFS_READ_LOCK; path->nodes[level - 1] = cur; unlock_up(path, level, 1); btrfs_clear_path_blocking(path, NULL, 0); } out: if (ret == 0) memcpy(min_key, &found_key, sizeof(found_key)); btrfs_set_path_blocking(path); return ret; } /* * this is similar to btrfs_next_leaf, but does not try to preserve * and fixup the path. It looks for and returns the next key in the * tree based on the current path and the cache_only and min_trans * parameters. * * 0 is returned if another key is found, < 0 if there are any errors * and 1 is returned if there are no higher keys in the tree * * path->keep_locks should be set to 1 on the search made before * calling this function. */ int btrfs_find_next_key(struct btrfs_root *root, struct btrfs_path *path, struct btrfs_key *key, int level, int cache_only, u64 min_trans) { int slot; struct extent_buffer *c; WARN_ON(!path->keep_locks); while (level < BTRFS_MAX_LEVEL) { if (!path->nodes[level]) return 1; slot = path->slots[level] + 1; c = path->nodes[level]; next: if (slot >= btrfs_header_nritems(c)) { int ret; int orig_lowest; struct btrfs_key cur_key; if (level + 1 >= BTRFS_MAX_LEVEL || !path->nodes[level + 1]) return 1; if (path->locks[level + 1]) { level++; continue; } slot = btrfs_header_nritems(c) - 1; if (level == 0) btrfs_item_key_to_cpu(c, &cur_key, slot); else btrfs_node_key_to_cpu(c, &cur_key, slot); orig_lowest = path->lowest_level; btrfs_release_path(path); path->lowest_level = level; ret = btrfs_search_slot(NULL, root, &cur_key, path, 0, 0); path->lowest_level = orig_lowest; if (ret < 0) return ret; c = path->nodes[level]; slot = path->slots[level]; if (ret == 0) slot++; goto next; } if (level == 0) btrfs_item_key_to_cpu(c, key, slot); else { u64 blockptr = btrfs_node_blockptr(c, slot); u64 gen = btrfs_node_ptr_generation(c, slot); if (cache_only) { struct extent_buffer *cur; cur = btrfs_find_tree_block(root, blockptr, btrfs_level_size(root, level - 1)); if (!cur || !btrfs_buffer_uptodate(cur, gen)) { slot++; if (cur) free_extent_buffer(cur); goto next; } free_extent_buffer(cur); } if (gen < min_trans) { slot++; goto next; } btrfs_node_key_to_cpu(c, key, slot); } return 0; } return 1; } /* * search the tree again to find a leaf with greater keys * returns 0 if it found something or 1 if there are no greater leaves. * returns < 0 on io errors. */ int btrfs_next_leaf(struct btrfs_root *root, struct btrfs_path *path) { int slot; int level; struct extent_buffer *c; struct extent_buffer *next; struct btrfs_key key; u32 nritems; int ret; int old_spinning = path->leave_spinning; int next_rw_lock = 0; nritems = btrfs_header_nritems(path->nodes[0]); if (nritems == 0) return 1; btrfs_item_key_to_cpu(path->nodes[0], &key, nritems - 1); again: level = 1; next = NULL; next_rw_lock = 0; btrfs_release_path(path); path->keep_locks = 1; path->leave_spinning = 1; ret = btrfs_search_slot(NULL, root, &key, path, 0, 0); path->keep_locks = 0; if (ret < 0) return ret; nritems = btrfs_header_nritems(path->nodes[0]); /* * by releasing the path above we dropped all our locks. A balance * could have added more items next to the key that used to be * at the very end of the block. So, check again here and * advance the path if there are now more items available. */ if (nritems > 0 && path->slots[0] < nritems - 1) { if (ret == 0) path->slots[0]++; ret = 0; goto done; } while (level < BTRFS_MAX_LEVEL) { if (!path->nodes[level]) { ret = 1; goto done; } slot = path->slots[level] + 1; c = path->nodes[level]; if (slot >= btrfs_header_nritems(c)) { level++; if (level == BTRFS_MAX_LEVEL) { ret = 1; goto done; } continue; } if (next) { btrfs_tree_unlock_rw(next, next_rw_lock); free_extent_buffer(next); } next = c; next_rw_lock = path->locks[level]; ret = read_block_for_search(NULL, root, path, &next, level, slot, &key); if (ret == -EAGAIN) goto again; if (ret < 0) { btrfs_release_path(path); goto done; } if (!path->skip_locking) { ret = btrfs_try_tree_read_lock(next); if (!ret) { btrfs_set_path_blocking(path); btrfs_tree_read_lock(next); btrfs_clear_path_blocking(path, next, BTRFS_READ_LOCK); } next_rw_lock = BTRFS_READ_LOCK; } break; } path->slots[level] = slot; while (1) { level--; c = path->nodes[level]; if (path->locks[level]) btrfs_tree_unlock_rw(c, path->locks[level]); free_extent_buffer(c); path->nodes[level] = next; path->slots[level] = 0; if (!path->skip_locking) path->locks[level] = next_rw_lock; if (!level) break; ret = read_block_for_search(NULL, root, path, &next, level, 0, &key); if (ret == -EAGAIN) goto again; if (ret < 0) { btrfs_release_path(path); goto done; } if (!path->skip_locking) { ret = btrfs_try_tree_read_lock(next); if (!ret) { btrfs_set_path_blocking(path); btrfs_tree_read_lock(next); btrfs_clear_path_blocking(path, next, BTRFS_READ_LOCK); } next_rw_lock = BTRFS_READ_LOCK; } } ret = 0; done: unlock_up(path, 0, 1); path->leave_spinning = old_spinning; if (!old_spinning) btrfs_set_path_blocking(path); return ret; } /* * this uses btrfs_prev_leaf to walk backwards in the tree, and keeps * searching until it gets past min_objectid or finds an item of 'type' * * returns 0 if something is found, 1 if nothing was found and < 0 on error */ int btrfs_previous_item(struct btrfs_root *root, struct btrfs_path *path, u64 min_objectid, int type) { struct btrfs_key found_key; struct extent_buffer *leaf; u32 nritems; int ret; while (1) { if (path->slots[0] == 0) { btrfs_set_path_blocking(path); ret = btrfs_prev_leaf(root, path); if (ret != 0) return ret; } else { path->slots[0]--; } leaf = path->nodes[0]; nritems = btrfs_header_nritems(leaf); if (nritems == 0) return 1; if (path->slots[0] == nritems) path->slots[0]--; btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]); if (found_key.objectid < min_objectid) break; if (found_key.type == type) return 0; if (found_key.objectid == min_objectid && found_key.type < type) break; } return 1; }