This implements ctrees, which are checksummed btrees. The btrfs
btree stores all data in the leaves and only has pointers to leaves
or nodes in the nodes. Data stored in the leaves is broken up
into two areas.
* Fixed sized item headers contain the keys, the offsets, and size of the
item data in the leaf
* Variable sized data
These two areas grow toward each other. Searches are done on the fixed
sized item headers, but all the useful data lives in the variable sized
data portion of the leaf.
Btrfs keys have three parts: [ u64 objectid, u8 type, u64 offset ]
The type field controls what the offset field means, and the objectid
field is generally the inode number, but this varies by the metadata
being stored.
All metadata in btrfs is indexed in one of these trees. The fields of
the key are used in different ways depending on which btree it is.
Signed-off-by: Chris Mason <chris.mason@xxxxxxxxxx>
--- /dev/null 2008-06-10 15:56:50.000000000 -0400
+++ b/fs/btrfs/ctree.c 2009-01-08 10:04:14.659535797 -0500
@@ -0,0 +1,2441 @@
+/*
+ * 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 "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);
+
+inline void btrfs_init_path(struct btrfs_path *p)
+{
+ memset(p, 0, sizeof(*p));
+}
+
+struct btrfs_path *btrfs_alloc_path(void)
+{
+ struct btrfs_path *path;
+ path = kmem_cache_alloc(btrfs_path_cachep, GFP_NOFS);
+ if (path) {
+ btrfs_init_path(path);
+ path->reada = 1;
+ }
+ return path;
+}
+
+/* this also releases the path */
+void btrfs_free_path(struct btrfs_path *p)
+{
+ btrfs_release_path(NULL, 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_root *root, 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(p->nodes[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;
+ spin_lock(&root->node_lock);
+ eb = root->node;
+ extent_buffer_get(eb);
+ spin_unlock(&root->node_lock);
+ 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);
+
+ spin_lock(&root->node_lock);
+ if (eb == root->node) {
+ spin_unlock(&root->node_lock);
+ break;
+ }
+ spin_unlock(&root->node_lock);
+
+ btrfs_tree_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;
+ u32 nritems;
+ int ret = 0;
+ int level;
+ struct btrfs_root *new_root;
+
+ new_root = kmalloc(sizeof(*new_root), GFP_NOFS);
+ if (!new_root)
+ return -ENOMEM;
+
+ memcpy(new_root, root, sizeof(*new_root));
+ new_root->root_key.objectid = new_root_objectid;
+
+ 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);
+ nritems = btrfs_header_nritems(buf);
+
+ cow = btrfs_alloc_free_block(trans, new_root, buf->len, 0,
+ new_root_objectid, trans->transid,
+ level, buf->start, 0);
+ if (IS_ERR(cow)) {
+ kfree(new_root);
+ 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_owner(cow, new_root_objectid);
+ btrfs_clear_header_flag(cow, BTRFS_HEADER_FLAG_WRITTEN);
+
+ 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);
+ ret = btrfs_inc_ref(trans, new_root, buf, cow, NULL);
+ kfree(new_root);
+
+ if (ret)
+ return ret;
+
+ btrfs_mark_buffer_dirty(cow);
+ *cow_ret = cow;
+ 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.
+ *
+ * prealloc_dest -- if you have already reserved a destination for the cow,
+ * this uses that block instead of allocating a new one.
+ * btrfs_alloc_reserved_extent is used to finish the allocation.
+ */
+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,
+ u64 prealloc_dest)
+{
+ u64 parent_start;
+ struct extent_buffer *cow;
+ u32 nritems;
+ int ret = 0;
+ int level;
+ int unlock_orig = 0;
+
+ if (*cow_ret == buf)
+ unlock_orig = 1;
+
+ WARN_ON(!btrfs_tree_locked(buf));
+
+ if (parent)
+ parent_start = parent->start;
+ else
+ parent_start = 0;
+
+ 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);
+ nritems = btrfs_header_nritems(buf);
+
+ if (prealloc_dest) {
+ struct btrfs_key ins;
+
+ ins.objectid = prealloc_dest;
+ ins.offset = buf->len;
+ ins.type = BTRFS_EXTENT_ITEM_KEY;
+
+ ret = btrfs_alloc_reserved_extent(trans, root, parent_start,
+ root->root_key.objectid,
+ trans->transid, level, &ins);
+ BUG_ON(ret);
+ cow = btrfs_init_new_buffer(trans, root, prealloc_dest,
+ buf->len);
+ } else {
+ cow = btrfs_alloc_free_block(trans, root, buf->len,
+ parent_start,
+ root->root_key.objectid,
+ trans->transid, level,
+ search_start, empty_size);
+ }
+ 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_owner(cow, root->root_key.objectid);
+ btrfs_clear_header_flag(cow, BTRFS_HEADER_FLAG_WRITTEN);
+
+ 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 (btrfs_header_generation(buf) != trans->transid) {
+ u32 nr_extents;
+ ret = btrfs_inc_ref(trans, root, buf, cow, &nr_extents);
+ if (ret)
+ return ret;
+
+ ret = btrfs_cache_ref(trans, root, buf, nr_extents);
+ WARN_ON(ret);
+ } else if (btrfs_header_owner(buf) == BTRFS_TREE_RELOC_OBJECTID) {
+ /*
+ * There are only two places that can drop reference to
+ * tree blocks owned by living reloc trees, one is here,
+ * the other place is btrfs_drop_subtree. In both places,
+ * we check reference count while tree block is locked.
+ * Furthermore, if reference count is one, it won't get
+ * increased by someone else.
+ */
+ u32 refs;
+ ret = btrfs_lookup_extent_ref(trans, root, buf->start,
+ buf->len, &refs);
+ BUG_ON(ret);
+ if (refs == 1) {
+ ret = btrfs_update_ref(trans, root, buf, cow,
+ 0, nritems);
+ clean_tree_block(trans, root, buf);
+ } else {
+ ret = btrfs_inc_ref(trans, root, buf, cow, NULL);
+ }
+ BUG_ON(ret);
+ } else {
+ ret = btrfs_update_ref(trans, root, buf, cow, 0, nritems);
+ if (ret)
+ return ret;
+ clean_tree_block(trans, root, buf);
+ }
+
+ if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID) {
+ ret = btrfs_reloc_tree_cache_ref(trans, root, cow, buf->start);
+ WARN_ON(ret);
+ }
+
+ if (buf == root->node) {
+ WARN_ON(parent && parent != buf);
+
+ spin_lock(&root->node_lock);
+ root->node = cow;
+ extent_buffer_get(cow);
+ spin_unlock(&root->node_lock);
+
+ if (buf != root->commit_root) {
+ btrfs_free_extent(trans, root, buf->start,
+ buf->len, buf->start,
+ root->root_key.objectid,
+ btrfs_header_generation(buf),
+ level, 1);
+ }
+ free_extent_buffer(buf);
+ add_root_to_dirty_list(root);
+ } else {
+ btrfs_set_node_blockptr(parent, parent_slot,
+ cow->start);
+ WARN_ON(trans->transid == 0);
+ btrfs_set_node_ptr_generation(parent, parent_slot,
+ trans->transid);
+ btrfs_mark_buffer_dirty(parent);
+ WARN_ON(btrfs_header_generation(parent) != trans->transid);
+ btrfs_free_extent(trans, root, buf->start, buf->len,
+ parent_start, btrfs_header_owner(parent),
+ btrfs_header_generation(parent), level, 1);
+ }
+ if (unlock_orig)
+ btrfs_tree_unlock(buf);
+ free_extent_buffer(buf);
+ btrfs_mark_buffer_dirty(cow);
+ *cow_ret = cow;
+ return 0;
+}
+
+/*
+ * 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 prealloc_dest)
+{
+ 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);
+ }
+
+ spin_lock(&root->fs_info->hash_lock);
+ if (btrfs_header_generation(buf) == trans->transid &&
+ btrfs_header_owner(buf) == root->root_key.objectid &&
+ !btrfs_header_flag(buf, BTRFS_HEADER_FLAG_WRITTEN)) {
+ *cow_ret = buf;
+ spin_unlock(&root->fs_info->hash_lock);
+ WARN_ON(prealloc_dest);
+ return 0;
+ }
+ spin_unlock(&root->fs_info->hash_lock);
+ search_start = buf->start & ~((u64)(1024 * 1024 * 1024) - 1);
+ ret = __btrfs_cow_block(trans, root, buf, parent,
+ parent_slot, cow_ret, search_start, 0,
+ prealloc_dest);
+ 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);
+
+ 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;
+}
+
+/*
+ * same as comp_keys only with two btrfs_key's
+ */
+static int 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;
+}
+
+/*
+ * 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);
+}
+
+/*
+ * extra debugging checks to make sure all the items in a key are
+ * well formed and in the proper order
+ */
+static int check_node(struct btrfs_root *root, struct btrfs_path *path,
+ int level)
+{
+ struct extent_buffer *parent = NULL;
+ struct extent_buffer *node = path->nodes[level];
+ struct btrfs_disk_key parent_key;
+ struct btrfs_disk_key node_key;
+ int parent_slot;
+ int slot;
+ struct btrfs_key cpukey;
+ u32 nritems = btrfs_header_nritems(node);
+
+ if (path->nodes[level + 1])
+ parent = path->nodes[level + 1];
+
+ slot = path->slots[level];
+ BUG_ON(nritems == 0);
+ if (parent) {
+ parent_slot = path->slots[level + 1];
+ btrfs_node_key(parent, &parent_key, parent_slot);
+ btrfs_node_key(node, &node_key, 0);
+ BUG_ON(memcmp(&parent_key, &node_key,
+ sizeof(struct btrfs_disk_key)));
+ BUG_ON(btrfs_node_blockptr(parent, parent_slot) !=
+ btrfs_header_bytenr(node));
+ }
+ BUG_ON(nritems > BTRFS_NODEPTRS_PER_BLOCK(root));
+ if (slot != 0) {
+ btrfs_node_key_to_cpu(node, &cpukey, slot - 1);
+ btrfs_node_key(node, &node_key, slot);
+ BUG_ON(comp_keys(&node_key, &cpukey) <= 0);
+ }
+ if (slot < nritems - 1) {
+ btrfs_node_key_to_cpu(node, &cpukey, slot + 1);
+ btrfs_node_key(node, &node_key, slot);
+ BUG_ON(comp_keys(&node_key, &cpukey) >= 0);
+ }
+ return 0;
+}
+
+/*
+ * extra checking to make sure all the items in a leaf are
+ * well formed and in the proper order
+ */
+static int check_leaf(struct btrfs_root *root, struct btrfs_path *path,
+ int level)
+{
+ struct extent_buffer *leaf = path->nodes[level];
+ struct extent_buffer *parent = NULL;
+ int parent_slot;
+ struct btrfs_key cpukey;
+ struct btrfs_disk_key parent_key;
+ struct btrfs_disk_key leaf_key;
+ int slot = path->slots[0];
+
+ u32 nritems = btrfs_header_nritems(leaf);
+
+ if (path->nodes[level + 1])
+ parent = path->nodes[level + 1];
+
+ if (nritems == 0)
+ return 0;
+
+ if (parent) {
+ parent_slot = path->slots[level + 1];
+ btrfs_node_key(parent, &parent_key, parent_slot);
+ btrfs_item_key(leaf, &leaf_key, 0);
+
+ BUG_ON(memcmp(&parent_key, &leaf_key,
+ sizeof(struct btrfs_disk_key)));
+ BUG_ON(btrfs_node_blockptr(parent, parent_slot) !=
+ btrfs_header_bytenr(leaf));
+ }
+ if (slot != 0 && slot < nritems - 1) {
+ btrfs_item_key(leaf, &leaf_key, slot);
+ btrfs_item_key_to_cpu(leaf, &cpukey, slot - 1);
+ if (comp_keys(&leaf_key, &cpukey) <= 0) {
+ btrfs_print_leaf(root, leaf);
+ printk(KERN_CRIT "slot %d offset bad key\n", slot);
+ BUG_ON(1);
+ }
+ if (btrfs_item_offset_nr(leaf, slot - 1) !=
+ btrfs_item_end_nr(leaf, slot)) {
+ btrfs_print_leaf(root, leaf);
+ printk(KERN_CRIT "slot %d offset bad\n", slot);
+ BUG_ON(1);
+ }
+ }
+ if (slot < nritems - 1) {
+ btrfs_item_key(leaf, &leaf_key, slot);
+ btrfs_item_key_to_cpu(leaf, &cpukey, slot + 1);
+ BUG_ON(comp_keys(&leaf_key, &cpukey) >= 0);
+ if (btrfs_item_offset_nr(leaf, slot) !=
+ btrfs_item_end_nr(leaf, slot + 1)) {
+ btrfs_print_leaf(root, leaf);
+ printk(KERN_CRIT "slot %d offset bad\n", slot);
+ BUG_ON(1);
+ }
+ }
+ BUG_ON(btrfs_item_offset_nr(leaf, 0) +
+ btrfs_item_size_nr(leaf, 0) != BTRFS_LEAF_DATA_SIZE(root));
+ return 0;
+}
+
+static noinline int check_block(struct btrfs_root *root,
+ struct btrfs_path *path, int level)
+{
+ return 0;
+ if (level == 0)
+ return check_leaf(root, path, level);
+ return check_node(root, path, level);
+}
+
+/*
+ * 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 *map_token = NULL;
+ 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 (!map_token || offset < map_start ||
+ (offset + sizeof(struct btrfs_disk_key)) >
+ map_start + map_len) {
+ if (map_token) {
+ unmap_extent_buffer(eb, map_token, KM_USER0);
+ map_token = NULL;
+ }
+
+ err = map_private_extent_buffer(eb, offset,
+ sizeof(struct btrfs_disk_key),
+ &map_token, &kaddr,
+ &map_start, &map_len, KM_USER0);
+
+ 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;
+ if (map_token)
+ unmap_extent_buffer(eb, map_token, KM_USER0);
+ return 0;
+ }
+ }
+ *slot = low;
+ if (map_token)
+ unmap_extent_buffer(eb, map_token, KM_USER0);
+ 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;
+}
+
+/* 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];
+ int err_on_enospc = 0;
+ u64 orig_ptr;
+
+ if (level == 0)
+ return 0;
+
+ mid = path->nodes[level];
+ WARN_ON(!path->locks[level]);
+ 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);
+ btrfs_tree_lock(child);
+ BUG_ON(!child);
+ ret = btrfs_cow_block(trans, root, child, mid, 0, &child, 0);
+ BUG_ON(ret);
+
+ spin_lock(&root->node_lock);
+ root->node = child;
+ spin_unlock(&root->node_lock);
+
+ ret = btrfs_update_extent_ref(trans, root, child->start,
+ mid->start, child->start,
+ root->root_key.objectid,
+ trans->transid, level - 1);
+ BUG_ON(ret);
+
+ 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);
+ ret = btrfs_free_extent(trans, root, mid->start, mid->len,
+ mid->start, root->root_key.objectid,
+ btrfs_header_generation(mid),
+ level, 1);
+ /* once for the root ptr */
+ free_extent_buffer(mid);
+ return ret;
+ }
+ if (btrfs_header_nritems(mid) >
+ BTRFS_NODEPTRS_PER_BLOCK(root) / 4)
+ return 0;
+
+ if (btrfs_header_nritems(mid) < 2)
+ err_on_enospc = 1;
+
+ left = read_node_slot(root, parent, pslot - 1);
+ if (left) {
+ btrfs_tree_lock(left);
+ wret = btrfs_cow_block(trans, root, left,
+ parent, pslot - 1, &left, 0);
+ if (wret) {
+ ret = wret;
+ goto enospc;
+ }
+ }
+ right = read_node_slot(root, parent, pslot + 1);
+ if (right) {
+ btrfs_tree_lock(right);
+ wret = btrfs_cow_block(trans, root, right,
+ parent, pslot + 1, &right, 0);
+ 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;
+ if (btrfs_header_nritems(mid) < 2)
+ err_on_enospc = 1;
+ }
+
+ /*
+ * 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) {
+ u64 bytenr = right->start;
+ u64 generation = btrfs_header_generation(parent);
+ u32 blocksize = right->len;
+
+ clean_tree_block(trans, root, right);
+ btrfs_tree_unlock(right);
+ free_extent_buffer(right);
+ right = NULL;
+ wret = del_ptr(trans, root, path, level + 1, pslot +
+ 1);
+ if (wret)
+ ret = wret;
+ wret = btrfs_free_extent(trans, root, bytenr,
+ blocksize, parent->start,
+ btrfs_header_owner(parent),
+ generation, level, 1);
+ if (wret)
+ ret = wret;
+ } 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) {
+ /* we've managed to empty the middle node, drop it */
+ u64 root_gen = btrfs_header_generation(parent);
+ u64 bytenr = mid->start;
+ u32 blocksize = mid->len;
+
+ clean_tree_block(trans, root, mid);
+ btrfs_tree_unlock(mid);
+ free_extent_buffer(mid);
+ mid = NULL;
+ wret = del_ptr(trans, root, path, level + 1, pslot);
+ if (wret)
+ ret = wret;
+ wret = btrfs_free_extent(trans, root, bytenr, blocksize,
+ parent->start,
+ btrfs_header_owner(parent),
+ root_gen, level, 1);
+ if (wret)
+ ret = wret;
+ } 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 */
+ check_block(root, path, level);
+ 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];
+ u64 orig_ptr;
+
+ if (level == 0)
+ return 1;
+
+ mid = path->nodes[level];
+ 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];
+
+ 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);
+ 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, 0);
+ 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);
+ 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, 0);
+ 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 noinline 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 lowest_read;
+ u64 highest_read;
+ u64 nread = 0;
+ 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;
+ }
+
+ highest_read = search;
+ lowest_read = 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 >= lowest_read && search <= highest_read) ||
+ (search < lowest_read && lowest_read - search <= 16384) ||
+ (search > highest_read && search - highest_read <= 16384)) {
+ readahead_tree_block(root, search, blocksize,
+ btrfs_node_ptr_generation(node, nr));
+ nread += blocksize;
+ }
+ nscan++;
+ if (path->reada < 2 && (nread > (64 * 1024) || nscan > 32))
+ break;
+
+ if (nread > (256 * 1024) || nscan > 128)
+ break;
+
+ if (search < lowest_read)
+ lowest_read = search;
+ if (search > highest_read)
+ highest_read = search;
+ }
+}
+
+/*
+ * 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(t);
+ path->locks[i] = 0;
+ }
+ }
+}
+
+/*
+ * 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;
+ struct extent_buffer *tmp;
+ int slot;
+ int ret;
+ int level;
+ int should_reada = p->reada;
+ int lowest_unlock = 1;
+ int blocksize;
+ u8 lowest_level = 0;
+ u64 blocknr;
+ u64 gen;
+ struct btrfs_key prealloc_block;
+
+ 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;
+
+ prealloc_block.objectid = 0;
+
+again:
+ if (p->skip_locking)
+ b = btrfs_root_node(root);
+ else
+ b = btrfs_lock_root_node(root);
+
+ while (b) {
+ level = btrfs_header_level(b);
+
+ /*
+ * setup the path here so we can release it under lock
+ * contention with the cow code
+ */
+ p->nodes[level] = b;
+ if (!p->skip_locking)
+ p->locks[level] = 1;
+
+ if (cow) {
+ int wret;
+
+ /* is a cow on this block not required */
+ spin_lock(&root->fs_info->hash_lock);
+ if (btrfs_header_generation(b) == trans->transid &&
+ btrfs_header_owner(b) == root->root_key.objectid &&
+ !btrfs_header_flag(b, BTRFS_HEADER_FLAG_WRITTEN)) {
+ spin_unlock(&root->fs_info->hash_lock);
+ goto cow_done;
+ }
+ spin_unlock(&root->fs_info->hash_lock);
+
+ /* ok, we have to cow, is our old prealloc the right
+ * size?
+ */
+ if (prealloc_block.objectid &&
+ prealloc_block.offset != b->len) {
+ btrfs_free_reserved_extent(root,
+ prealloc_block.objectid,
+ prealloc_block.offset);
+ prealloc_block.objectid = 0;
+ }
+
+ /*
+ * for higher level blocks, try not to allocate blocks
+ * with the block and the parent locks held.
+ */
+ if (level > 1 && !prealloc_block.objectid &&
+ btrfs_path_lock_waiting(p, level)) {
+ u32 size = b->len;
+ u64 hint = b->start;
+
+ btrfs_release_path(root, p);
+ ret = btrfs_reserve_extent(trans, root,
+ size, size, 0,
+ hint, (u64)-1,
+ &prealloc_block, 0);
+ BUG_ON(ret);
+ goto again;
+ }
+
+ wret = btrfs_cow_block(trans, root, b,
+ p->nodes[level + 1],
+ p->slots[level + 1],
+ &b, prealloc_block.objectid);
+ prealloc_block.objectid = 0;
+ if (wret) {
+ free_extent_buffer(b);
+ ret = wret;
+ goto done;
+ }
+ }
+cow_done:
+ BUG_ON(!cow && ins_len);
+ if (level != btrfs_header_level(b))
+ WARN_ON(1);
+ level = btrfs_header_level(b);
+
+ p->nodes[level] = b;
+ if (!p->skip_locking)
+ p->locks[level] = 1;
+
+ ret = check_block(root, p, level);
+ if (ret) {
+ ret = -1;
+ goto done;
+ }
+
+ ret = bin_search(b, key, level, &slot);
+ if (level != 0) {
+ if (ret && slot > 0)
+ slot -= 1;
+ p->slots[level] = slot;
+ if ((p->search_for_split || ins_len > 0) &&
+ btrfs_header_nritems(b) >=
+ BTRFS_NODEPTRS_PER_BLOCK(root) - 3) {
+ int sret = split_node(trans, root, p, level);
+ BUG_ON(sret > 0);
+ if (sret) {
+ ret = sret;
+ goto done;
+ }
+ b = p->nodes[level];
+ slot = p->slots[level];
+ } else if (ins_len < 0) {
+ int sret = balance_level(trans, root, p,
+ level);
+ if (sret) {
+ ret = sret;
+ goto done;
+ }
+ b = p->nodes[level];
+ if (!b) {
+ btrfs_release_path(NULL, p);
+ goto again;
+ }
+ slot = p->slots[level];
+ BUG_ON(btrfs_header_nritems(b) == 1);
+ }
+ unlock_up(p, level, lowest_unlock);
+
+ /* this is only true while dropping a snapshot */
+ if (level == lowest_level) {
+ ret = 0;
+ goto done;
+ }
+
+ 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 && btrfs_buffer_uptodate(tmp, gen)) {
+ b = tmp;
+ } else {
+ /*
+ * reduce lock contention at high levels
+ * of the btree by dropping locks before
+ * we read.
+ */
+ if (level > 1) {
+ btrfs_release_path(NULL, p);
+ if (tmp)
+ free_extent_buffer(tmp);
+ if (should_reada)
+ reada_for_search(root, p,
+ level, slot,
+ key->objectid);
+
+ tmp = read_tree_block(root, blocknr,
+ blocksize, gen);
+ if (tmp)
+ free_extent_buffer(tmp);
+ goto again;
+ } else {
+ if (tmp)
+ free_extent_buffer(tmp);
+ if (should_reada)
+ reada_for_search(root, p,
+ level, slot,
+ key->objectid);
+ b = read_node_slot(root, b, slot);
+ }
+ }
+ if (!p->skip_locking)
+ btrfs_tree_lock(b);
+ } else {
+ p->slots[level] = slot;
+ if (ins_len > 0 &&
+ btrfs_leaf_free_space(root, b) < ins_len) {
+ int sret = split_leaf(trans, root, key,
+ p, ins_len, ret == 0);
+ BUG_ON(sret > 0);
+ if (sret) {
+ ret = sret;
+ goto done;
+ }
+ }
+ if (!p->search_for_split)
+ unlock_up(p, level, lowest_unlock);
+ goto done;
+ }
+ }
+ ret = 1;
+done:
+ if (prealloc_block.objectid) {
+ btrfs_free_reserved_extent(root,
+ prealloc_block.objectid,
+ prealloc_block.offset);
+ }
+
+ 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;
+}
+
+
+/*
+ * 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);
+
+ ret = btrfs_update_ref(trans, root, src, dst, dst_nritems, push_items);
+ BUG_ON(ret);
+
+ 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);
+
+ ret = btrfs_update_ref(trans, root, src, dst, 0, push_items);
+ BUG_ON(ret);
+
+ return ret;
+}
+
+/*
+ * 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]);
+ lower = path->nodes[level];
+ nritems = btrfs_header_nritems(lower);
+ if (slot > nritems)
+ BUG();
+ 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);
+
+ split = btrfs_alloc_free_block(trans, root, root->nodesize,
+ path->nodes[level + 1]->start,
+ root->root_key.objectid,
+ trans->transid, level, c->start, 0);
+ if (IS_ERR(split))
+ return PTR_ERR(split);
+
+ btrfs_set_header_flags(split, btrfs_header_flags(c));
+ 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_owner(split, root->root_key.objectid);
+ btrfs_set_header_flags(split, 0);
+ 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);
+
+ mid = (c_nritems + 1) / 2;
+
+ 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);
+
+ btrfs_node_key(split, &disk_key, 0);
+ wret = insert_ptr(trans, root, path, &disk_key, split->start,
+ path->slots[level + 1] + 1,
+ level + 1);
+ if (wret)
+ ret = wret;
+
+ ret = btrfs_update_ref(trans, root, c, split, 0, c_nritems - mid);
+ BUG_ON(ret);
+
+ 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;
+}
+
+/*
+ * 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.
+ */
+static 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 *left = path->nodes[0];
+ struct extent_buffer *right;
+ struct extent_buffer *upper;
+ struct btrfs_disk_key disk_key;
+ int slot;
+ u32 i;
+ int free_space;
+ int push_space = 0;
+ int push_items = 0;
+ struct btrfs_item *item;
+ u32 left_nritems;
+ u32 nr;
+ u32 right_nritems;
+ u32 data_end;
+ u32 this_item_size;
+ int ret;
+
+ slot = path->slots[1];
+ if (!path->nodes[1])
+ return 1;
+
+ upper = path->nodes[1];
+ if (slot >= btrfs_header_nritems(upper) - 1)
+ return 1;
+
+ WARN_ON(!btrfs_tree_locked(path->nodes[1]));
+
+ right = read_node_slot(root, upper, slot + 1);
+ btrfs_tree_lock(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, 0);
+ 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;
+
+ if (empty)
+ nr = 0;
+ else
+ nr = 1;
+
+ if (path->slots[0] >= left_nritems)
+ push_space += data_size;
+
+ 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;
+
+ if (!left->map_token) {
+ map_extent_buffer(left, (unsigned long)item,
+ sizeof(struct btrfs_item),
+ &left->map_token, &left->kaddr,
+ &left->map_start, &left->map_len,
+ KM_USER1);
+ }
+
+ 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 (left->map_token) {
+ unmap_extent_buffer(left, left->map_token, KM_USER1);
+ left->map_token = NULL;
+ }
+
+ 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);
+ if (!right->map_token) {
+ map_extent_buffer(right, (unsigned long)item,
+ sizeof(struct btrfs_item),
+ &right->map_token, &right->kaddr,
+ &right->map_start, &right->map_len,
+ KM_USER1);
+ }
+ push_space -= btrfs_item_size(right, item);
+ btrfs_set_item_offset(right, item, push_space);
+ }
+
+ if (right->map_token) {
+ unmap_extent_buffer(right, right->map_token, KM_USER1);
+ right->map_token = NULL;
+ }
+ left_nritems -= push_items;
+ btrfs_set_header_nritems(left, left_nritems);
+
+ if (left_nritems)
+ btrfs_mark_buffer_dirty(left);
+ btrfs_mark_buffer_dirty(right);
+
+ ret = btrfs_update_ref(trans, root, left, right, 0, push_items);
+ BUG_ON(ret);
+
+ 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 left, trying to free up at
+ * least data_size bytes. returns zero if the push worked, nonzero otherwise
+ */
+static int push_leaf_left(struct btrfs_trans_handle *trans, struct btrfs_root
+ *root, struct btrfs_path *path, int data_size,
+ int empty)
+{
+ struct btrfs_disk_key disk_key;
+ struct extent_buffer *right = path->nodes[0];
+ struct extent_buffer *left;
+ int slot;
+ int i;
+ int free_space;
+ int push_space = 0;
+ int push_items = 0;
+ struct btrfs_item *item;
+ u32 old_left_nritems;
+ u32 right_nritems;
+ u32 nr;
+ int ret = 0;
+ int wret;
+ u32 this_item_size;
+ u32 old_left_item_size;
+
+ 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;
+
+ WARN_ON(!btrfs_tree_locked(path->nodes[1]));
+
+ left = read_node_slot(root, path->nodes[1], slot - 1);
+ btrfs_tree_lock(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, 0);
+ 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;
+ }
+
+ if (empty)
+ nr = right_nritems;
+ else
+ nr = right_nritems - 1;
+
+ for (i = 0; i < nr; i++) {
+ item = btrfs_item_nr(right, i);
+ if (!right->map_token) {
+ map_extent_buffer(right, (unsigned long)item,
+ sizeof(struct btrfs_item),
+ &right->map_token, &right->kaddr,
+ &right->map_start, &right->map_len,
+ KM_USER1);
+ }
+
+ 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 (right->map_token) {
+ unmap_extent_buffer(right, right->map_token, KM_USER1);
+ right->map_token = NULL;
+ }
+
+ 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);
+ if (!left->map_token) {
+ map_extent_buffer(left, (unsigned long)item,
+ sizeof(struct btrfs_item),
+ &left->map_token, &left->kaddr,
+ &left->map_start, &left->map_len,
+ KM_USER1);
+ }
+
+ 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);
+ if (left->map_token) {
+ unmap_extent_buffer(left, left->map_token, KM_USER1);
+ left->map_token = NULL;
+ }
+
+ /* 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);
+
+ if (!right->map_token) {
+ map_extent_buffer(right, (unsigned long)item,
+ sizeof(struct btrfs_item),
+ &right->map_token, &right->kaddr,
+ &right->map_start, &right->map_len,
+ KM_USER1);
+ }
+
+ push_space = push_space - btrfs_item_size(right, item);
+ btrfs_set_item_offset(right, item, push_space);
+ }
+ if (right->map_token) {
+ unmap_extent_buffer(right, right->map_token, KM_USER1);
+ right->map_token = NULL;
+ }
+
+ btrfs_mark_buffer_dirty(left);
+ if (right_nritems)
+ btrfs_mark_buffer_dirty(right);
+
+ ret = btrfs_update_ref(trans, root, right, left,
+ old_left_nritems, push_items);
+ BUG_ON(ret);
+
+ 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;
+ 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] = 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;
+}
+
+/*
+ * 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 extent_buffer *l;
+ u32 nritems;
+ int mid;
+ int slot;
+ struct extent_buffer *right;
+ int data_copy_size;
+ int rt_data_off;
+ int i;
+ int ret = 0;
+ int wret;
+ int double_split;
+ int num_doubles = 0;
+ struct btrfs_disk_key disk_key;
+
+ /* first try to make some room by pushing left and right */
+ if (data_size && ins_key->type != BTRFS_DIR_ITEM_KEY) {
+ wret = push_leaf_right(trans, root, path, data_size, 0);
+ if (wret < 0)
+ return wret;
+ if (wret) {
+ wret = push_leaf_left(trans, root, path, data_size, 0);
+ 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:
+ double_split = 0;
+ l = path->nodes[0];
+ slot = path->slots[0];
+ nritems = btrfs_header_nritems(l);
+ mid = (nritems + 1) / 2;
+
+ right = btrfs_alloc_free_block(trans, root, root->leafsize,
+ path->nodes[1]->start,
+ root->root_key.objectid,
+ trans->transid, 0, l->start, 0);
+ if (IS_ERR(right)) {
+ BUG_ON(1);
+ return PTR_ERR(right);
+ }
+
+ 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_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 (mid <= slot) {
+ if (nritems == 1 ||
+ leaf_space_used(l, mid, nritems - mid) + data_size >
+ BTRFS_LEAF_DATA_SIZE(root)) {
+ if (slot >= nritems) {
+ btrfs_cpu_key_to_disk(&disk_key, ins_key);
+ 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;
+ btrfs_mark_buffer_dirty(right);
+ return ret;
+ }
+ mid = slot;
+ if (mid != nritems &&
+ leaf_space_used(l, mid, nritems - mid) +
+ data_size > BTRFS_LEAF_DATA_SIZE(root)) {
+ double_split = 1;
+ }
+ }
+ } else {
+ if (leaf_space_used(l, 0, mid) + data_size >
+ BTRFS_LEAF_DATA_SIZE(root)) {
+ if (!extend && data_size && slot == 0) {
+ btrfs_cpu_key_to_disk(&disk_key, ins_key);
+ 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;
+ } 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)) {
+ double_split = 1;
+ }
+ }
+ }
+ }
+ 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;
+
+ if (!right->map_token) {
+ map_extent_buffer(right, (unsigned long)item,
+ sizeof(struct btrfs_item),
+ &right->map_token, &right->kaddr,
+ &right->map_start, &right->map_len,
+ KM_USER1);
+ }
+
+ ioff = btrfs_item_offset(right, item);
+ btrfs_set_item_offset(right, item, ioff + rt_data_off);
+ }
+
+ if (right->map_token) {
+ unmap_extent_buffer(right, right->map_token, KM_USER1);
+ right->map_token = NULL;
+ }
+
+ 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);
+
+ ret = btrfs_update_ref(trans, root, l, right, 0, nritems);
+ BUG_ON(ret);
+
+ 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);
+
+ if (double_split) {
+ BUG_ON(num_doubles != 0);
+ num_doubles++;
+ goto again;
+ }
+ 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;
+}
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