summaryrefslogtreecommitdiffstats
path: root/fs/btrfs/ctree.c
diff options
context:
space:
mode:
Diffstat (limited to 'fs/btrfs/ctree.c')
-rw-r--r--fs/btrfs/ctree.c5011
1 files changed, 5011 insertions, 0 deletions
diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c
new file mode 100644
index 000000000..e08688844
--- /dev/null
+++ b/fs/btrfs/ctree.c
@@ -0,0 +1,5011 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2007,2008 Oracle. All rights reserved.
+ */
+
+#include <linux/sched.h>
+#include <linux/slab.h>
+#include <linux/rbtree.h>
+#include <linux/mm.h>
+#include <linux/error-injection.h>
+#include "ctree.h"
+#include "disk-io.h"
+#include "transaction.h"
+#include "print-tree.h"
+#include "locking.h"
+#include "volumes.h"
+#include "qgroup.h"
+#include "tree-mod-log.h"
+#include "tree-checker.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,
+ const 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 extent_buffer *dst,
+ struct extent_buffer *src, int empty);
+static int balance_node_right(struct btrfs_trans_handle *trans,
+ struct extent_buffer *dst_buf,
+ struct extent_buffer *src_buf);
+static void del_ptr(struct btrfs_root *root, struct btrfs_path *path,
+ int level, int slot);
+
+static const struct btrfs_csums {
+ u16 size;
+ const char name[10];
+ const char driver[12];
+} btrfs_csums[] = {
+ [BTRFS_CSUM_TYPE_CRC32] = { .size = 4, .name = "crc32c" },
+ [BTRFS_CSUM_TYPE_XXHASH] = { .size = 8, .name = "xxhash64" },
+ [BTRFS_CSUM_TYPE_SHA256] = { .size = 32, .name = "sha256" },
+ [BTRFS_CSUM_TYPE_BLAKE2] = { .size = 32, .name = "blake2b",
+ .driver = "blake2b-256" },
+};
+
+int btrfs_super_csum_size(const struct btrfs_super_block *s)
+{
+ u16 t = btrfs_super_csum_type(s);
+ /*
+ * csum type is validated at mount time
+ */
+ return btrfs_csums[t].size;
+}
+
+const char *btrfs_super_csum_name(u16 csum_type)
+{
+ /* csum type is validated at mount time */
+ return btrfs_csums[csum_type].name;
+}
+
+/*
+ * Return driver name if defined, otherwise the name that's also a valid driver
+ * name
+ */
+const char *btrfs_super_csum_driver(u16 csum_type)
+{
+ /* csum type is validated at mount time */
+ return btrfs_csums[csum_type].driver[0] ?
+ btrfs_csums[csum_type].driver :
+ btrfs_csums[csum_type].name;
+}
+
+size_t __attribute_const__ btrfs_get_num_csums(void)
+{
+ return ARRAY_SIZE(btrfs_csums);
+}
+
+struct btrfs_path *btrfs_alloc_path(void)
+{
+ return kmem_cache_zalloc(btrfs_path_cachep, GFP_NOFS);
+}
+
+/* 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;
+ }
+}
+
+/*
+ * We want the transaction abort to print stack trace only for errors where the
+ * cause could be a bug, eg. due to ENOSPC, and not for common errors that are
+ * caused by external factors.
+ */
+bool __cold abort_should_print_stack(int errno)
+{
+ switch (errno) {
+ case -EIO:
+ case -EROFS:
+ case -ENOMEM:
+ return false;
+ }
+ return true;
+}
+
+/*
+ * 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;
+
+ while (1) {
+ rcu_read_lock();
+ eb = rcu_dereference(root->node);
+
+ /*
+ * RCU really hurts here, we could free up the root node because
+ * it was COWed but we may not get the new root node yet so do
+ * the inc_not_zero dance and if it doesn't work then
+ * synchronize_rcu and try again.
+ */
+ if (atomic_inc_not_zero(&eb->refs)) {
+ rcu_read_unlock();
+ break;
+ }
+ rcu_read_unlock();
+ synchronize_rcu();
+ }
+ return eb;
+}
+
+/*
+ * Cowonly root (not-shareable trees, everything not subvolume or reloc roots),
+ * just get put onto a simple dirty list. Transaction walks this list to make
+ * sure they get properly updated on disk.
+ */
+static void add_root_to_dirty_list(struct btrfs_root *root)
+{
+ struct btrfs_fs_info *fs_info = root->fs_info;
+
+ if (test_bit(BTRFS_ROOT_DIRTY, &root->state) ||
+ !test_bit(BTRFS_ROOT_TRACK_DIRTY, &root->state))
+ return;
+
+ spin_lock(&fs_info->trans_lock);
+ if (!test_and_set_bit(BTRFS_ROOT_DIRTY, &root->state)) {
+ /* Want the extent tree to be the last on the list */
+ if (root->root_key.objectid == BTRFS_EXTENT_TREE_OBJECTID)
+ list_move_tail(&root->dirty_list,
+ &fs_info->dirty_cowonly_roots);
+ else
+ list_move(&root->dirty_list,
+ &fs_info->dirty_cowonly_roots);
+ }
+ spin_unlock(&fs_info->trans_lock);
+}
+
+/*
+ * 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 btrfs_fs_info *fs_info = root->fs_info;
+ struct extent_buffer *cow;
+ int ret = 0;
+ int level;
+ struct btrfs_disk_key disk_key;
+
+ WARN_ON(test_bit(BTRFS_ROOT_SHAREABLE, &root->state) &&
+ trans->transid != fs_info->running_transaction->transid);
+ WARN_ON(test_bit(BTRFS_ROOT_SHAREABLE, &root->state) &&
+ 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_tree_block(trans, root, 0, new_root_objectid,
+ &disk_key, level, buf->start, 0,
+ BTRFS_NESTING_NEW_ROOT);
+ if (IS_ERR(cow))
+ return PTR_ERR(cow);
+
+ copy_extent_buffer_full(cow, buf);
+ 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_fsid(cow, fs_info->fs_devices->metadata_uuid);
+
+ WARN_ON(btrfs_header_generation(buf) > trans->transid);
+ if (new_root_objectid == BTRFS_TREE_RELOC_OBJECTID)
+ ret = btrfs_inc_ref(trans, root, cow, 1);
+ else
+ ret = btrfs_inc_ref(trans, root, cow, 0);
+ if (ret) {
+ btrfs_tree_unlock(cow);
+ free_extent_buffer(cow);
+ btrfs_abort_transaction(trans, 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 shareable 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 (test_bit(BTRFS_ROOT_SHAREABLE, &root->state) &&
+ 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;
+
+ 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)
+{
+ struct btrfs_fs_info *fs_info = root->fs_info;
+ 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, fs_info, buf->start,
+ btrfs_header_level(buf), 1,
+ &refs, &flags);
+ if (ret)
+ return ret;
+ if (refs == 0) {
+ ret = -EROFS;
+ btrfs_handle_fs_error(fs_info, ret, NULL);
+ return ret;
+ }
+ } 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);
+ if (ret)
+ return ret;
+
+ if (root->root_key.objectid ==
+ BTRFS_TREE_RELOC_OBJECTID) {
+ ret = btrfs_dec_ref(trans, root, buf, 0);
+ if (ret)
+ return ret;
+ ret = btrfs_inc_ref(trans, root, cow, 1);
+ if (ret)
+ return 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);
+ else
+ ret = btrfs_inc_ref(trans, root, cow, 0);
+ if (ret)
+ return ret;
+ }
+ if (new_flags != 0) {
+ int level = btrfs_header_level(buf);
+
+ ret = btrfs_set_disk_extent_flags(trans, buf,
+ new_flags, level);
+ if (ret)
+ return 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);
+ else
+ ret = btrfs_inc_ref(trans, root, cow, 0);
+ if (ret)
+ return ret;
+ ret = btrfs_dec_ref(trans, root, buf, 1);
+ if (ret)
+ return ret;
+ }
+ btrfs_clean_tree_block(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,
+ enum btrfs_lock_nesting nest)
+{
+ struct btrfs_fs_info *fs_info = root->fs_info;
+ struct btrfs_disk_key disk_key;
+ struct extent_buffer *cow;
+ int level, ret;
+ int last_ref = 0;
+ int unlock_orig = 0;
+ u64 parent_start = 0;
+
+ if (*cow_ret == buf)
+ unlock_orig = 1;
+
+ btrfs_assert_tree_write_locked(buf);
+
+ WARN_ON(test_bit(BTRFS_ROOT_SHAREABLE, &root->state) &&
+ trans->transid != fs_info->running_transaction->transid);
+ WARN_ON(test_bit(BTRFS_ROOT_SHAREABLE, &root->state) &&
+ 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) && parent)
+ parent_start = parent->start;
+
+ cow = btrfs_alloc_tree_block(trans, root, parent_start,
+ root->root_key.objectid, &disk_key, level,
+ search_start, empty_size, nest);
+ if (IS_ERR(cow))
+ return PTR_ERR(cow);
+
+ /* cow is set to blocking by btrfs_init_new_buffer */
+
+ copy_extent_buffer_full(cow, buf);
+ 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_fsid(cow, fs_info->fs_devices->metadata_uuid);
+
+ ret = update_ref_for_cow(trans, root, buf, cow, &last_ref);
+ if (ret) {
+ btrfs_tree_unlock(cow);
+ free_extent_buffer(cow);
+ btrfs_abort_transaction(trans, ret);
+ return ret;
+ }
+
+ if (test_bit(BTRFS_ROOT_SHAREABLE, &root->state)) {
+ ret = btrfs_reloc_cow_block(trans, root, buf, cow);
+ if (ret) {
+ btrfs_tree_unlock(cow);
+ free_extent_buffer(cow);
+ btrfs_abort_transaction(trans, ret);
+ return ret;
+ }
+ }
+
+ 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;
+
+ ret = btrfs_tree_mod_log_insert_root(root->node, cow, true);
+ if (ret < 0) {
+ btrfs_tree_unlock(cow);
+ free_extent_buffer(cow);
+ btrfs_abort_transaction(trans, ret);
+ return ret;
+ }
+ atomic_inc(&cow->refs);
+ rcu_assign_pointer(root->node, cow);
+
+ btrfs_free_tree_block(trans, btrfs_root_id(root), buf,
+ parent_start, last_ref);
+ free_extent_buffer(buf);
+ add_root_to_dirty_list(root);
+ } else {
+ WARN_ON(trans->transid != btrfs_header_generation(parent));
+ btrfs_tree_mod_log_insert_key(parent, parent_slot,
+ BTRFS_MOD_LOG_KEY_REPLACE, GFP_NOFS);
+ btrfs_set_node_blockptr(parent, parent_slot,
+ cow->start);
+ btrfs_set_node_ptr_generation(parent, parent_slot,
+ trans->transid);
+ btrfs_mark_buffer_dirty(parent);
+ if (last_ref) {
+ ret = btrfs_tree_mod_log_free_eb(buf);
+ if (ret) {
+ btrfs_tree_unlock(cow);
+ free_extent_buffer(cow);
+ btrfs_abort_transaction(trans, ret);
+ return ret;
+ }
+ }
+ btrfs_free_tree_block(trans, btrfs_root_id(root), buf,
+ parent_start, last_ref);
+ }
+ if (unlock_orig)
+ btrfs_tree_unlock(buf);
+ free_extent_buffer_stale(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)
+{
+ if (btrfs_is_testing(root->fs_info))
+ return 0;
+
+ /* Ensure we can see the FORCE_COW bit */
+ smp_mb__before_atomic();
+
+ /*
+ * 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 committing the transaction,
+ * after we've finished copying 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)) &&
+ !test_bit(BTRFS_ROOT_FORCE_COW, &root->state))
+ 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 COWed 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,
+ enum btrfs_lock_nesting nest)
+{
+ struct btrfs_fs_info *fs_info = root->fs_info;
+ u64 search_start;
+ int ret;
+
+ if (unlikely(test_bit(BTRFS_ROOT_DELETING, &root->state))) {
+ btrfs_abort_transaction(trans, -EUCLEAN);
+ btrfs_crit(fs_info,
+ "attempt to COW block %llu on root %llu that is being deleted",
+ buf->start, btrfs_root_id(root));
+ return -EUCLEAN;
+ }
+
+ /*
+ * COWing must happen through a running transaction, which always
+ * matches the current fs generation (it's a transaction with a state
+ * less than TRANS_STATE_UNBLOCKED). If it doesn't, then turn the fs
+ * into error state to prevent the commit of any transaction.
+ */
+ if (unlikely(trans->transaction != fs_info->running_transaction ||
+ trans->transid != fs_info->generation)) {
+ btrfs_abort_transaction(trans, -EUCLEAN);
+ btrfs_crit(fs_info,
+"unexpected transaction when attempting to COW block %llu on root %llu, transaction %llu running transaction %llu fs generation %llu",
+ buf->start, btrfs_root_id(root), trans->transid,
+ fs_info->running_transaction->transid,
+ fs_info->generation);
+ return -EUCLEAN;
+ }
+
+ if (!should_cow_block(trans, root, buf)) {
+ *cow_ret = buf;
+ return 0;
+ }
+
+ search_start = buf->start & ~((u64)SZ_1G - 1);
+
+ /*
+ * Before CoWing this block for later modification, check if it's
+ * the subtree root and do the delayed subtree trace if needed.
+ *
+ * Also We don't care about the error, as it's handled internally.
+ */
+ btrfs_qgroup_trace_subtree_after_cow(trans, root, buf);
+ ret = __btrfs_cow_block(trans, root, buf, parent,
+ parent_slot, cow_ret, search_start, 0, nest);
+
+ trace_btrfs_cow_block(root, buf, *cow_ret);
+
+ return ret;
+}
+ALLOW_ERROR_INJECTION(btrfs_cow_block, ERRNO);
+
+/*
+ * 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;
+}
+
+#ifdef __LITTLE_ENDIAN
+
+/*
+ * Compare two keys, on little-endian the disk order is same as CPU order and
+ * we can avoid the conversion.
+ */
+static int comp_keys(const struct btrfs_disk_key *disk_key,
+ const struct btrfs_key *k2)
+{
+ const struct btrfs_key *k1 = (const struct btrfs_key *)disk_key;
+
+ return btrfs_comp_cpu_keys(k1, k2);
+}
+
+#else
+
+/*
+ * compare two keys in a memcmp fashion
+ */
+static int comp_keys(const struct btrfs_disk_key *disk,
+ const struct btrfs_key *k2)
+{
+ struct btrfs_key k1;
+
+ btrfs_disk_key_to_cpu(&k1, disk);
+
+ return btrfs_comp_cpu_keys(&k1, k2);
+}
+#endif
+
+/*
+ * same as comp_keys only with two btrfs_key's
+ */
+int __pure btrfs_comp_cpu_keys(const struct btrfs_key *k1, const 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, u64 *last_ret,
+ struct btrfs_key *progress)
+{
+ struct btrfs_fs_info *fs_info = root->fs_info;
+ struct extent_buffer *cur;
+ u64 blocknr;
+ u64 search_start = *last_ret;
+ u64 last_block = 0;
+ u64 other;
+ u32 parent_nritems;
+ int end_slot;
+ int i;
+ int err = 0;
+ u32 blocksize;
+ int progress_passed = 0;
+ struct btrfs_disk_key disk_key;
+
+ /*
+ * COWing must happen through a running transaction, which always
+ * matches the current fs generation (it's a transaction with a state
+ * less than TRANS_STATE_UNBLOCKED). If it doesn't, then turn the fs
+ * into error state to prevent the commit of any transaction.
+ */
+ if (unlikely(trans->transaction != fs_info->running_transaction ||
+ trans->transid != fs_info->generation)) {
+ btrfs_abort_transaction(trans, -EUCLEAN);
+ btrfs_crit(fs_info,
+"unexpected transaction when attempting to reallocate parent %llu for root %llu, transaction %llu running transaction %llu fs generation %llu",
+ parent->start, btrfs_root_id(root), trans->transid,
+ fs_info->running_transaction->transid,
+ fs_info->generation);
+ return -EUCLEAN;
+ }
+
+ parent_nritems = btrfs_header_nritems(parent);
+ blocksize = fs_info->nodesize;
+ end_slot = parent_nritems - 1;
+
+ if (parent_nritems <= 1)
+ return 0;
+
+ 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);
+ 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) {
+ other = btrfs_node_blockptr(parent, i + 1);
+ close = close_blocks(blocknr, other, blocksize);
+ }
+ if (close) {
+ last_block = blocknr;
+ continue;
+ }
+
+ cur = btrfs_read_node_slot(parent, i);
+ if (IS_ERR(cur))
+ return PTR_ERR(cur);
+ if (search_start == 0)
+ search_start = last_block;
+
+ btrfs_tree_lock(cur);
+ err = __btrfs_cow_block(trans, root, cur, parent, i,
+ &cur, search_start,
+ min(16 * blocksize,
+ (end_slot - i) * blocksize),
+ BTRFS_NESTING_COW);
+ 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;
+}
+
+/*
+ * Search for a key in the given extent_buffer.
+ *
+ * The lower boundary for the search is specified by the slot number @low. Use a
+ * value of 0 to search over the whole extent buffer.
+ *
+ * The slot in the extent buffer is returned via @slot. If the key exists in the
+ * extent buffer, then @slot will point to the slot where the key is, otherwise
+ * it points to the slot where you would insert the key.
+ *
+ * Slot may point to the total number of items (i.e. one position beyond the last
+ * key) if the key is bigger than the last key in the extent buffer.
+ */
+static noinline int generic_bin_search(struct extent_buffer *eb, int low,
+ const struct btrfs_key *key, int *slot)
+{
+ unsigned long p;
+ int item_size;
+ int high = btrfs_header_nritems(eb);
+ int ret;
+ const int key_size = sizeof(struct btrfs_disk_key);
+
+ if (low > high) {
+ btrfs_err(eb->fs_info,
+ "%s: low (%d) > high (%d) eb %llu owner %llu level %d",
+ __func__, low, high, eb->start,
+ btrfs_header_owner(eb), btrfs_header_level(eb));
+ return -EINVAL;
+ }
+
+ if (btrfs_header_level(eb) == 0) {
+ p = offsetof(struct btrfs_leaf, items);
+ item_size = sizeof(struct btrfs_item);
+ } else {
+ p = offsetof(struct btrfs_node, ptrs);
+ item_size = sizeof(struct btrfs_key_ptr);
+ }
+
+ while (low < high) {
+ unsigned long oip;
+ unsigned long offset;
+ struct btrfs_disk_key *tmp;
+ struct btrfs_disk_key unaligned;
+ int mid;
+
+ mid = (low + high) / 2;
+ offset = p + mid * item_size;
+ oip = offset_in_page(offset);
+
+ if (oip + key_size <= PAGE_SIZE) {
+ const unsigned long idx = get_eb_page_index(offset);
+ char *kaddr = page_address(eb->pages[idx]);
+
+ oip = get_eb_offset_in_page(eb, offset);
+ tmp = (struct btrfs_disk_key *)(kaddr + oip);
+ } else {
+ read_extent_buffer(eb, &unaligned, offset, key_size);
+ tmp = &unaligned;
+ }
+
+ 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 binary search on an extent buffer. Works for both leaves and nodes, and
+ * always searches over the whole range of keys (slot 0 to slot 'nritems - 1').
+ */
+int btrfs_bin_search(struct extent_buffer *eb, const struct btrfs_key *key,
+ int *slot)
+{
+ return generic_bin_search(eb, 0, key, 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).
+ */
+struct extent_buffer *btrfs_read_node_slot(struct extent_buffer *parent,
+ int slot)
+{
+ int level = btrfs_header_level(parent);
+ struct extent_buffer *eb;
+ struct btrfs_key first_key;
+
+ if (slot < 0 || slot >= btrfs_header_nritems(parent))
+ return ERR_PTR(-ENOENT);
+
+ BUG_ON(level == 0);
+
+ btrfs_node_key_to_cpu(parent, &first_key, slot);
+ eb = read_tree_block(parent->fs_info, btrfs_node_blockptr(parent, slot),
+ btrfs_header_owner(parent),
+ btrfs_node_ptr_generation(parent, slot),
+ level - 1, &first_key);
+ if (IS_ERR(eb))
+ return eb;
+ if (!extent_buffer_uptodate(eb)) {
+ free_extent_buffer(eb);
+ return ERR_PTR(-EIO);
+ }
+
+ return eb;
+}
+
+/*
+ * 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 btrfs_fs_info *fs_info = root->fs_info;
+ 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;
+
+ ASSERT(level > 0);
+
+ mid = path->nodes[level];
+
+ WARN_ON(path->locks[level] != BTRFS_WRITE_LOCK);
+ 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 = btrfs_read_node_slot(mid, 0);
+ if (IS_ERR(child)) {
+ ret = PTR_ERR(child);
+ btrfs_handle_fs_error(fs_info, ret, NULL);
+ goto enospc;
+ }
+
+ btrfs_tree_lock(child);
+ ret = btrfs_cow_block(trans, root, child, mid, 0, &child,
+ BTRFS_NESTING_COW);
+ if (ret) {
+ btrfs_tree_unlock(child);
+ free_extent_buffer(child);
+ goto enospc;
+ }
+
+ ret = btrfs_tree_mod_log_insert_root(root->node, child, true);
+ if (ret < 0) {
+ btrfs_tree_unlock(child);
+ free_extent_buffer(child);
+ btrfs_abort_transaction(trans, ret);
+ 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;
+ btrfs_clean_tree_block(mid);
+ btrfs_tree_unlock(mid);
+ /* once for the path */
+ free_extent_buffer(mid);
+
+ root_sub_used(root, mid->len);
+ btrfs_free_tree_block(trans, btrfs_root_id(root), mid, 0, 1);
+ /* once for the root ptr */
+ free_extent_buffer_stale(mid);
+ return 0;
+ }
+ if (btrfs_header_nritems(mid) >
+ BTRFS_NODEPTRS_PER_BLOCK(fs_info) / 4)
+ return 0;
+
+ left = btrfs_read_node_slot(parent, pslot - 1);
+ if (IS_ERR(left))
+ left = NULL;
+
+ if (left) {
+ __btrfs_tree_lock(left, BTRFS_NESTING_LEFT);
+ wret = btrfs_cow_block(trans, root, left,
+ parent, pslot - 1, &left,
+ BTRFS_NESTING_LEFT_COW);
+ if (wret) {
+ ret = wret;
+ goto enospc;
+ }
+ }
+
+ right = btrfs_read_node_slot(parent, pslot + 1);
+ if (IS_ERR(right))
+ right = NULL;
+
+ if (right) {
+ __btrfs_tree_lock(right, BTRFS_NESTING_RIGHT);
+ wret = btrfs_cow_block(trans, root, right,
+ parent, pslot + 1, &right,
+ BTRFS_NESTING_RIGHT_COW);
+ 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, left, mid, 1);
+ if (wret < 0)
+ ret = wret;
+ }
+
+ /*
+ * then try to empty the right most buffer into the middle
+ */
+ if (right) {
+ wret = push_node_left(trans, mid, right, 1);
+ if (wret < 0 && wret != -ENOSPC)
+ ret = wret;
+ if (btrfs_header_nritems(right) == 0) {
+ btrfs_clean_tree_block(right);
+ btrfs_tree_unlock(right);
+ del_ptr(root, path, level + 1, pslot + 1);
+ root_sub_used(root, right->len);
+ btrfs_free_tree_block(trans, btrfs_root_id(root), right,
+ 0, 1);
+ free_extent_buffer_stale(right);
+ right = NULL;
+ } else {
+ struct btrfs_disk_key right_key;
+ btrfs_node_key(right, &right_key, 0);
+ ret = btrfs_tree_mod_log_insert_key(parent, pslot + 1,
+ BTRFS_MOD_LOG_KEY_REPLACE, GFP_NOFS);
+ if (ret < 0) {
+ btrfs_abort_transaction(trans, ret);
+ goto enospc;
+ }
+ 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
+ */
+ if (!left) {
+ ret = -EROFS;
+ btrfs_handle_fs_error(fs_info, ret, NULL);
+ goto enospc;
+ }
+ wret = balance_node_right(trans, mid, left);
+ if (wret < 0) {
+ ret = wret;
+ goto enospc;
+ }
+ if (wret == 1) {
+ wret = push_node_left(trans, left, mid, 1);
+ if (wret < 0)
+ ret = wret;
+ }
+ BUG_ON(wret == 1);
+ }
+ if (btrfs_header_nritems(mid) == 0) {
+ btrfs_clean_tree_block(mid);
+ btrfs_tree_unlock(mid);
+ del_ptr(root, path, level + 1, pslot);
+ root_sub_used(root, mid->len);
+ btrfs_free_tree_block(trans, btrfs_root_id(root), mid, 0, 1);
+ free_extent_buffer_stale(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);
+ ret = btrfs_tree_mod_log_insert_key(parent, pslot,
+ BTRFS_MOD_LOG_KEY_REPLACE, GFP_NOFS);
+ if (ret < 0) {
+ btrfs_abort_transaction(trans, ret);
+ goto enospc;
+ }
+ 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) {
+ atomic_inc(&left->refs);
+ /* 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 btrfs_fs_info *fs_info = root->fs_info;
+ 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 = btrfs_read_node_slot(parent, pslot - 1);
+ if (IS_ERR(left))
+ left = NULL;
+
+ /* first, try to make some room in the middle buffer */
+ if (left) {
+ u32 left_nr;
+
+ __btrfs_tree_lock(left, BTRFS_NESTING_LEFT);
+
+ left_nr = btrfs_header_nritems(left);
+ if (left_nr >= BTRFS_NODEPTRS_PER_BLOCK(fs_info) - 1) {
+ wret = 1;
+ } else {
+ ret = btrfs_cow_block(trans, root, left, parent,
+ pslot - 1, &left,
+ BTRFS_NESTING_LEFT_COW);
+ if (ret)
+ wret = 1;
+ else {
+ wret = push_node_left(trans, 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);
+ ret = btrfs_tree_mod_log_insert_key(parent, pslot,
+ BTRFS_MOD_LOG_KEY_REPLACE, GFP_NOFS);
+ BUG_ON(ret < 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 = btrfs_read_node_slot(parent, pslot + 1);
+ if (IS_ERR(right))
+ right = NULL;
+
+ /*
+ * then try to empty the right most buffer into the middle
+ */
+ if (right) {
+ u32 right_nr;
+
+ __btrfs_tree_lock(right, BTRFS_NESTING_RIGHT);
+
+ right_nr = btrfs_header_nritems(right);
+ if (right_nr >= BTRFS_NODEPTRS_PER_BLOCK(fs_info) - 1) {
+ wret = 1;
+ } else {
+ ret = btrfs_cow_block(trans, root, right,
+ parent, pslot + 1,
+ &right, BTRFS_NESTING_RIGHT_COW);
+ if (ret)
+ wret = 1;
+ else {
+ wret = balance_node_right(trans, right, mid);
+ }
+ }
+ if (wret < 0)
+ ret = wret;
+ if (wret == 0) {
+ struct btrfs_disk_key disk_key;
+
+ btrfs_node_key(right, &disk_key, 0);
+ ret = btrfs_tree_mod_log_insert_key(parent, pslot + 1,
+ BTRFS_MOD_LOG_KEY_REPLACE, GFP_NOFS);
+ BUG_ON(ret < 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_fs_info *fs_info,
+ 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 nread_max;
+ u32 nr;
+ u32 blocksize;
+ u32 nscan = 0;
+
+ if (level != 1 && path->reada != READA_FORWARD_ALWAYS)
+ return;
+
+ if (!path->nodes[level])
+ return;
+
+ node = path->nodes[level];
+
+ /*
+ * Since the time between visiting leaves is much shorter than the time
+ * between visiting nodes, limit read ahead of nodes to 1, to avoid too
+ * much IO at once (possibly random).
+ */
+ if (path->reada == READA_FORWARD_ALWAYS) {
+ if (level > 1)
+ nread_max = node->fs_info->nodesize;
+ else
+ nread_max = SZ_128K;
+ } else {
+ nread_max = SZ_64K;
+ }
+
+ search = btrfs_node_blockptr(node, slot);
+ blocksize = fs_info->nodesize;
+ if (path->reada != READA_FORWARD_ALWAYS) {
+ struct extent_buffer *eb;
+
+ eb = find_extent_buffer(fs_info, search);
+ if (eb) {
+ free_extent_buffer(eb);
+ return;
+ }
+ }
+
+ target = search;
+
+ nritems = btrfs_header_nritems(node);
+ nr = slot;
+
+ while (1) {
+ if (path->reada == READA_BACK) {
+ if (nr == 0)
+ break;
+ nr--;
+ } else if (path->reada == READA_FORWARD ||
+ path->reada == READA_FORWARD_ALWAYS) {
+ nr++;
+ if (nr >= nritems)
+ break;
+ }
+ if (path->reada == READA_BACK && objectid) {
+ btrfs_node_key(node, &disk_key, nr);
+ if (btrfs_disk_key_objectid(&disk_key) != objectid)
+ break;
+ }
+ search = btrfs_node_blockptr(node, nr);
+ if (path->reada == READA_FORWARD_ALWAYS ||
+ (search <= target && target - search <= 65536) ||
+ (search > target && search - target <= 65536)) {
+ btrfs_readahead_node_child(node, nr);
+ nread += blocksize;
+ }
+ nscan++;
+ if (nread > nread_max || nscan > 32)
+ break;
+ }
+}
+
+static noinline void reada_for_balance(struct btrfs_path *path, int level)
+{
+ struct extent_buffer *parent;
+ int slot;
+ int nritems;
+
+ parent = path->nodes[level + 1];
+ if (!parent)
+ return;
+
+ nritems = btrfs_header_nritems(parent);
+ slot = path->slots[level + 1];
+
+ if (slot > 0)
+ btrfs_readahead_node_child(parent, slot - 1);
+ if (slot + 1 < nritems)
+ btrfs_readahead_node_child(parent, slot + 1);
+}
+
+
+/*
+ * 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 min_write_lock_level,
+ int *write_lock_level)
+{
+ int i;
+ int skip_level = level;
+ bool check_skip = true;
+
+ for (i = level; i < BTRFS_MAX_LEVEL; i++) {
+ if (!path->nodes[i])
+ break;
+ if (!path->locks[i])
+ break;
+
+ if (check_skip) {
+ if (path->slots[i] == 0) {
+ skip_level = i + 1;
+ continue;
+ }
+
+ if (path->keep_locks) {
+ u32 nritems;
+
+ nritems = btrfs_header_nritems(path->nodes[i]);
+ if (nritems < 1 || path->slots[i] >= nritems - 1) {
+ skip_level = i + 1;
+ continue;
+ }
+ }
+ }
+
+ if (i >= lowest_unlock && i > skip_level) {
+ check_skip = false;
+ btrfs_tree_unlock_rw(path->nodes[i], path->locks[i]);
+ path->locks[i] = 0;
+ if (write_lock_level &&
+ i > min_write_lock_level &&
+ i <= *write_lock_level) {
+ *write_lock_level = i - 1;
+ }
+ }
+ }
+}
+
+/*
+ * Helper function for btrfs_search_slot() and other functions that do a search
+ * on a btree. The goal is to find a tree block in the cache (the radix tree at
+ * fs_info->buffer_radix), but if we can't find it, or it's not up to date, read
+ * its pages from disk.
+ *
+ * Returns -EAGAIN, with the path unlocked, if the caller needs to repeat the
+ * whole btree search, starting again from the current root node.
+ */
+static int
+read_block_for_search(struct btrfs_root *root, struct btrfs_path *p,
+ struct extent_buffer **eb_ret, int level, int slot,
+ const struct btrfs_key *key)
+{
+ struct btrfs_fs_info *fs_info = root->fs_info;
+ u64 blocknr;
+ u64 gen;
+ struct extent_buffer *tmp;
+ struct btrfs_key first_key;
+ int ret;
+ int parent_level;
+ bool unlock_up;
+
+ unlock_up = ((level + 1 < BTRFS_MAX_LEVEL) && p->locks[level + 1]);
+ blocknr = btrfs_node_blockptr(*eb_ret, slot);
+ gen = btrfs_node_ptr_generation(*eb_ret, slot);
+ parent_level = btrfs_header_level(*eb_ret);
+ btrfs_node_key_to_cpu(*eb_ret, &first_key, slot);
+
+ /*
+ * If we need to read an extent buffer from disk and we are holding locks
+ * on upper level nodes, we unlock all the upper nodes before reading the
+ * extent buffer, and then return -EAGAIN to the caller as it needs to
+ * restart the search. We don't release the lock on the current level
+ * because we need to walk this node to figure out which blocks to read.
+ */
+ tmp = find_extent_buffer(fs_info, blocknr);
+ if (tmp) {
+ if (p->reada == READA_FORWARD_ALWAYS)
+ reada_for_search(fs_info, p, level, slot, key->objectid);
+
+ /* first we do an atomic uptodate check */
+ if (btrfs_buffer_uptodate(tmp, gen, 1) > 0) {
+ /*
+ * Do extra check for first_key, eb can be stale due to
+ * being cached, read from scrub, or have multiple
+ * parents (shared tree blocks).
+ */
+ if (btrfs_verify_level_key(tmp,
+ parent_level - 1, &first_key, gen)) {
+ free_extent_buffer(tmp);
+ return -EUCLEAN;
+ }
+ *eb_ret = tmp;
+ return 0;
+ }
+
+ if (p->nowait) {
+ free_extent_buffer(tmp);
+ return -EAGAIN;
+ }
+
+ if (unlock_up)
+ btrfs_unlock_up_safe(p, level + 1);
+
+ /* now we're allowed to do a blocking uptodate check */
+ ret = btrfs_read_extent_buffer(tmp, gen, parent_level - 1, &first_key);
+ if (ret) {
+ free_extent_buffer(tmp);
+ btrfs_release_path(p);
+ return -EIO;
+ }
+ if (btrfs_check_eb_owner(tmp, root->root_key.objectid)) {
+ free_extent_buffer(tmp);
+ btrfs_release_path(p);
+ return -EUCLEAN;
+ }
+
+ if (unlock_up)
+ ret = -EAGAIN;
+
+ goto out;
+ } else if (p->nowait) {
+ return -EAGAIN;
+ }
+
+ if (unlock_up) {
+ btrfs_unlock_up_safe(p, level + 1);
+ ret = -EAGAIN;
+ } else {
+ ret = 0;
+ }
+
+ if (p->reada != READA_NONE)
+ reada_for_search(fs_info, p, level, slot, key->objectid);
+
+ tmp = read_tree_block(fs_info, blocknr, root->root_key.objectid,
+ gen, parent_level - 1, &first_key);
+ if (IS_ERR(tmp)) {
+ btrfs_release_path(p);
+ return PTR_ERR(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 (!extent_buffer_uptodate(tmp))
+ ret = -EIO;
+
+out:
+ if (ret == 0) {
+ *eb_ret = tmp;
+ } else {
+ free_extent_buffer(tmp);
+ btrfs_release_path(p);
+ }
+
+ 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)
+{
+ struct btrfs_fs_info *fs_info = root->fs_info;
+ int ret = 0;
+
+ if ((p->search_for_split || ins_len > 0) && btrfs_header_nritems(b) >=
+ BTRFS_NODEPTRS_PER_BLOCK(fs_info) - 3) {
+
+ if (*write_lock_level < level + 1) {
+ *write_lock_level = level + 1;
+ btrfs_release_path(p);
+ return -EAGAIN;
+ }
+
+ reada_for_balance(p, level);
+ ret = split_node(trans, root, p, level);
+
+ b = p->nodes[level];
+ } else if (ins_len < 0 && btrfs_header_nritems(b) <
+ BTRFS_NODEPTRS_PER_BLOCK(fs_info) / 2) {
+
+ if (*write_lock_level < level + 1) {
+ *write_lock_level = level + 1;
+ btrfs_release_path(p);
+ return -EAGAIN;
+ }
+
+ reada_for_balance(p, level);
+ ret = balance_level(trans, root, p, level);
+ if (ret)
+ return ret;
+
+ b = p->nodes[level];
+ if (!b) {
+ btrfs_release_path(p);
+ return -EAGAIN;
+ }
+ BUG_ON(btrfs_header_nritems(b) == 1);
+ }
+ return ret;
+}
+
+int btrfs_find_item(struct btrfs_root *fs_root, struct btrfs_path *path,
+ u64 iobjectid, u64 ioff, u8 key_type,
+ struct btrfs_key *found_key)
+{
+ int ret;
+ struct btrfs_key key;
+ struct extent_buffer *eb;
+
+ ASSERT(path);
+ ASSERT(found_key);
+
+ key.type = key_type;
+ key.objectid = iobjectid;
+ key.offset = ioff;
+
+ ret = btrfs_search_slot(NULL, fs_root, &key, path, 0, 0);
+ if (ret < 0)
+ return ret;
+
+ eb = path->nodes[0];
+ if (ret && path->slots[0] >= btrfs_header_nritems(eb)) {
+ ret = btrfs_next_leaf(fs_root, path);
+ if (ret)
+ return ret;
+ eb = path->nodes[0];
+ }
+
+ btrfs_item_key_to_cpu(eb, found_key, path->slots[0]);
+ if (found_key->type != key.type ||
+ found_key->objectid != key.objectid)
+ return 1;
+
+ return 0;
+}
+
+static struct extent_buffer *btrfs_search_slot_get_root(struct btrfs_root *root,
+ struct btrfs_path *p,
+ int write_lock_level)
+{
+ struct extent_buffer *b;
+ int root_lock = 0;
+ int level = 0;
+
+ if (p->search_commit_root) {
+ b = root->commit_root;
+ atomic_inc(&b->refs);
+ level = btrfs_header_level(b);
+ /*
+ * Ensure that all callers have set skip_locking when
+ * p->search_commit_root = 1.
+ */
+ ASSERT(p->skip_locking == 1);
+
+ goto out;
+ }
+
+ if (p->skip_locking) {
+ b = btrfs_root_node(root);
+ level = btrfs_header_level(b);
+ goto out;
+ }
+
+ /* We try very hard to do read locks on the root */
+ root_lock = BTRFS_READ_LOCK;
+
+ /*
+ * If the level is set to maximum, we can skip trying to get the read
+ * lock.
+ */
+ if (write_lock_level < BTRFS_MAX_LEVEL) {
+ /*
+ * We don't know the level of the root node until we actually
+ * have it read locked
+ */
+ if (p->nowait) {
+ b = btrfs_try_read_lock_root_node(root);
+ if (IS_ERR(b))
+ return b;
+ } else {
+ b = btrfs_read_lock_root_node(root);
+ }
+ level = btrfs_header_level(b);
+ if (level > write_lock_level)
+ goto out;
+
+ /* 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);
+
+out:
+ /*
+ * The root may have failed to write out at some point, and thus is no
+ * longer valid, return an error in this case.
+ */
+ if (!extent_buffer_uptodate(b)) {
+ if (root_lock)
+ btrfs_tree_unlock_rw(b, root_lock);
+ free_extent_buffer(b);
+ return ERR_PTR(-EIO);
+ }
+
+ p->nodes[level] = b;
+ if (!p->skip_locking)
+ p->locks[level] = root_lock;
+ /*
+ * Callers are responsible for dropping b's references.
+ */
+ return b;
+}
+
+/*
+ * Replace the extent buffer at the lowest level of the path with a cloned
+ * version. The purpose is to be able to use it safely, after releasing the
+ * commit root semaphore, even if relocation is happening in parallel, the
+ * transaction used for relocation is committed and the extent buffer is
+ * reallocated in the next transaction.
+ *
+ * This is used in a context where the caller does not prevent transaction
+ * commits from happening, either by holding a transaction handle or holding
+ * some lock, while it's doing searches through a commit root.
+ * At the moment it's only used for send operations.
+ */
+static int finish_need_commit_sem_search(struct btrfs_path *path)
+{
+ const int i = path->lowest_level;
+ const int slot = path->slots[i];
+ struct extent_buffer *lowest = path->nodes[i];
+ struct extent_buffer *clone;
+
+ ASSERT(path->need_commit_sem);
+
+ if (!lowest)
+ return 0;
+
+ lockdep_assert_held_read(&lowest->fs_info->commit_root_sem);
+
+ clone = btrfs_clone_extent_buffer(lowest);
+ if (!clone)
+ return -ENOMEM;
+
+ btrfs_release_path(path);
+ path->nodes[i] = clone;
+ path->slots[i] = slot;
+
+ return 0;
+}
+
+static inline int search_for_key_slot(struct extent_buffer *eb,
+ int search_low_slot,
+ const struct btrfs_key *key,
+ int prev_cmp,
+ int *slot)
+{
+ /*
+ * If a previous call to btrfs_bin_search() on a parent node returned an
+ * exact match (prev_cmp == 0), we can safely assume the target key will
+ * always be at slot 0 on lower levels, since each key pointer
+ * (struct btrfs_key_ptr) refers to the lowest key accessible from the
+ * subtree it points to. Thus we can skip searching lower levels.
+ */
+ if (prev_cmp == 0) {
+ *slot = 0;
+ return 0;
+ }
+
+ return generic_bin_search(eb, search_low_slot, key, slot);
+}
+
+static int search_leaf(struct btrfs_trans_handle *trans,
+ struct btrfs_root *root,
+ const struct btrfs_key *key,
+ struct btrfs_path *path,
+ int ins_len,
+ int prev_cmp)
+{
+ struct extent_buffer *leaf = path->nodes[0];
+ int leaf_free_space = -1;
+ int search_low_slot = 0;
+ int ret;
+ bool do_bin_search = true;
+
+ /*
+ * If we are doing an insertion, the leaf has enough free space and the
+ * destination slot for the key is not slot 0, then we can unlock our
+ * write lock on the parent, and any other upper nodes, before doing the
+ * binary search on the leaf (with search_for_key_slot()), allowing other
+ * tasks to lock the parent and any other upper nodes.
+ */
+ if (ins_len > 0) {
+ /*
+ * Cache the leaf free space, since we will need it later and it
+ * will not change until then.
+ */
+ leaf_free_space = btrfs_leaf_free_space(leaf);
+
+ /*
+ * !path->locks[1] means we have a single node tree, the leaf is
+ * the root of the tree.
+ */
+ if (path->locks[1] && leaf_free_space >= ins_len) {
+ struct btrfs_disk_key first_key;
+
+ ASSERT(btrfs_header_nritems(leaf) > 0);
+ btrfs_item_key(leaf, &first_key, 0);
+
+ /*
+ * Doing the extra comparison with the first key is cheap,
+ * taking into account that the first key is very likely
+ * already in a cache line because it immediately follows
+ * the extent buffer's header and we have recently accessed
+ * the header's level field.
+ */
+ ret = comp_keys(&first_key, key);
+ if (ret < 0) {
+ /*
+ * The first key is smaller than the key we want
+ * to insert, so we are safe to unlock all upper
+ * nodes and we have to do the binary search.
+ *
+ * We do use btrfs_unlock_up_safe() and not
+ * unlock_up() because the later does not unlock
+ * nodes with a slot of 0 - we can safely unlock
+ * any node even if its slot is 0 since in this
+ * case the key does not end up at slot 0 of the
+ * leaf and there's no need to split the leaf.
+ */
+ btrfs_unlock_up_safe(path, 1);
+ search_low_slot = 1;
+ } else {
+ /*
+ * The first key is >= then the key we want to
+ * insert, so we can skip the binary search as
+ * the target key will be at slot 0.
+ *
+ * We can not unlock upper nodes when the key is
+ * less than the first key, because we will need
+ * to update the key at slot 0 of the parent node
+ * and possibly of other upper nodes too.
+ * If the key matches the first key, then we can
+ * unlock all the upper nodes, using
+ * btrfs_unlock_up_safe() instead of unlock_up()
+ * as stated above.
+ */
+ if (ret == 0)
+ btrfs_unlock_up_safe(path, 1);
+ /*
+ * ret is already 0 or 1, matching the result of
+ * a btrfs_bin_search() call, so there is no need
+ * to adjust it.
+ */
+ do_bin_search = false;
+ path->slots[0] = 0;
+ }
+ }
+ }
+
+ if (do_bin_search) {
+ ret = search_for_key_slot(leaf, search_low_slot, key,
+ prev_cmp, &path->slots[0]);
+ if (ret < 0)
+ return ret;
+ }
+
+ if (ins_len > 0) {
+ /*
+ * Item key already exists. In this case, if we are allowed to
+ * insert the item (for example, in dir_item case, item key
+ * collision is allowed), it will be merged with the original
+ * item. Only the item size grows, no new btrfs item will be
+ * added. If search_for_extension is not set, ins_len already
+ * accounts the size btrfs_item, deduct it here so leaf space
+ * check will be correct.
+ */
+ if (ret == 0 && !path->search_for_extension) {
+ ASSERT(ins_len >= sizeof(struct btrfs_item));
+ ins_len -= sizeof(struct btrfs_item);
+ }
+
+ ASSERT(leaf_free_space >= 0);
+
+ if (leaf_free_space < ins_len) {
+ int err;
+
+ err = split_leaf(trans, root, key, path, ins_len,
+ (ret == 0));
+ ASSERT(err <= 0);
+ if (WARN_ON(err > 0))
+ err = -EUCLEAN;
+ if (err)
+ ret = err;
+ }
+ }
+
+ return ret;
+}
+
+/*
+ * btrfs_search_slot - look for a key in a tree and perform necessary
+ * modifications to preserve tree invariants.
+ *
+ * @trans: Handle of transaction, used when modifying the tree
+ * @p: Holds all btree nodes along the search path
+ * @root: The root node of the tree
+ * @key: The key we are looking for
+ * @ins_len: Indicates purpose of search:
+ * >0 for inserts it's size of item inserted (*)
+ * <0 for deletions
+ * 0 for plain searches, not modifying the tree
+ *
+ * (*) If size of item inserted doesn't include
+ * sizeof(struct btrfs_item), then p->search_for_extension must
+ * be set.
+ * @cow: boolean should CoW operations be performed. Must always be 1
+ * when modifying the tree.
+ *
+ * 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)
+ *
+ * If @key is found, 0 is returned and you can find the item in the leaf level
+ * of the path (level 0)
+ *
+ * If @key isn't found, 1 is returned and the leaf level of the path (level 0)
+ * points to the slot where it should be inserted
+ *
+ * If an error is encountered while searching the tree a negative error number
+ * is returned
+ */
+int btrfs_search_slot(struct btrfs_trans_handle *trans, struct btrfs_root *root,
+ const struct btrfs_key *key, struct btrfs_path *p,
+ int ins_len, int cow)
+{
+ struct btrfs_fs_info *fs_info = root->fs_info;
+ struct extent_buffer *b;
+ int slot;
+ int ret;
+ int err;
+ int level;
+ int lowest_unlock = 1;
+ /* everything at write_lock_level or lower must be write locked */
+ int write_lock_level = 0;
+ u8 lowest_level = 0;
+ int min_write_lock_level;
+ int prev_cmp;
+
+ lowest_level = p->lowest_level;
+ WARN_ON(lowest_level && ins_len > 0);
+ WARN_ON(p->nodes[0] != NULL);
+ BUG_ON(!cow && ins_len);
+
+ /*
+ * For now only allow nowait for read only operations. There's no
+ * strict reason why we can't, we just only need it for reads so it's
+ * only implemented for reads.
+ */
+ ASSERT(!p->nowait || !cow);
+
+ 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;
+
+ min_write_lock_level = write_lock_level;
+
+ if (p->need_commit_sem) {
+ ASSERT(p->search_commit_root);
+ if (p->nowait) {
+ if (!down_read_trylock(&fs_info->commit_root_sem))
+ return -EAGAIN;
+ } else {
+ down_read(&fs_info->commit_root_sem);
+ }
+ }
+
+again:
+ prev_cmp = -1;
+ b = btrfs_search_slot_get_root(root, p, write_lock_level);
+ if (IS_ERR(b)) {
+ ret = PTR_ERR(b);
+ goto done;
+ }
+
+ while (b) {
+ int dec = 0;
+
+ level = btrfs_header_level(b);
+
+ if (cow) {
+ bool last_level = (level == (BTRFS_MAX_LEVEL - 1));
+
+ /*
+ * 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;
+
+ /*
+ * must have write locks on this node and the
+ * parent
+ */
+ if (level > write_lock_level ||
+ (level + 1 > write_lock_level &&
+ level + 1 < BTRFS_MAX_LEVEL &&
+ p->nodes[level + 1])) {
+ write_lock_level = level + 1;
+ btrfs_release_path(p);
+ goto again;
+ }
+
+ if (last_level)
+ err = btrfs_cow_block(trans, root, b, NULL, 0,
+ &b,
+ BTRFS_NESTING_COW);
+ else
+ err = btrfs_cow_block(trans, root, b,
+ p->nodes[level + 1],
+ p->slots[level + 1], &b,
+ BTRFS_NESTING_COW);
+ if (err) {
+ ret = err;
+ goto done;
+ }
+ }
+cow_done:
+ p->nodes[level] = b;
+
+ /*
+ * 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 we're inserting or deleting (ins_len != 0), 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 (!ins_len && !p->keep_locks) {
+ int u = level + 1;
+
+ if (u < BTRFS_MAX_LEVEL && p->locks[u]) {
+ btrfs_tree_unlock_rw(p->nodes[u], p->locks[u]);
+ p->locks[u] = 0;
+ }
+ }
+
+ if (level == 0) {
+ if (ins_len > 0)
+ ASSERT(write_lock_level >= 1);
+
+ ret = search_leaf(trans, root, key, p, ins_len, prev_cmp);
+ if (!p->search_for_split)
+ unlock_up(p, level, lowest_unlock,
+ min_write_lock_level, NULL);
+ goto done;
+ }
+
+ ret = search_for_key_slot(b, 0, key, prev_cmp, &slot);
+ if (ret < 0)
+ goto done;
+ prev_cmp = ret;
+
+ if (ret && slot > 0) {
+ dec = 1;
+ slot--;
+ }
+ 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 && ins_len && write_lock_level < level + 1) {
+ write_lock_level = level + 1;
+ btrfs_release_path(p);
+ goto again;
+ }
+
+ unlock_up(p, level, lowest_unlock, min_write_lock_level,
+ &write_lock_level);
+
+ if (level == lowest_level) {
+ if (dec)
+ p->slots[level]++;
+ goto done;
+ }
+
+ err = read_block_for_search(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);
+
+ btrfs_maybe_reset_lockdep_class(root, b);
+
+ if (level <= write_lock_level) {
+ btrfs_tree_lock(b);
+ p->locks[level] = BTRFS_WRITE_LOCK;
+ } else {
+ if (p->nowait) {
+ if (!btrfs_try_tree_read_lock(b)) {
+ free_extent_buffer(b);
+ ret = -EAGAIN;
+ goto done;
+ }
+ } else {
+ btrfs_tree_read_lock(b);
+ }
+ p->locks[level] = BTRFS_READ_LOCK;
+ }
+ p->nodes[level] = b;
+ }
+ }
+ ret = 1;
+done:
+ if (ret < 0 && !p->skip_release_on_error)
+ btrfs_release_path(p);
+
+ if (p->need_commit_sem) {
+ int ret2;
+
+ ret2 = finish_need_commit_sem_search(p);
+ up_read(&fs_info->commit_root_sem);
+ if (ret2)
+ ret = ret2;
+ }
+
+ return ret;
+}
+ALLOW_ERROR_INJECTION(btrfs_search_slot, ERRNO);
+
+/*
+ * Like btrfs_search_slot, this looks for a key in the given tree. It uses the
+ * current state of the tree together with the operations recorded in the tree
+ * modification log to search for the key in a previous version of this tree, as
+ * denoted by the time_seq parameter.
+ *
+ * Naturally, there is no support for insert, delete or cow operations.
+ *
+ * The resulting path and return value will be set up as if we called
+ * btrfs_search_slot at that point in time with ins_len and cow both set to 0.
+ */
+int btrfs_search_old_slot(struct btrfs_root *root, const struct btrfs_key *key,
+ struct btrfs_path *p, u64 time_seq)
+{
+ struct btrfs_fs_info *fs_info = root->fs_info;
+ struct extent_buffer *b;
+ int slot;
+ int ret;
+ int err;
+ int level;
+ int lowest_unlock = 1;
+ u8 lowest_level = 0;
+
+ lowest_level = p->lowest_level;
+ WARN_ON(p->nodes[0] != NULL);
+ ASSERT(!p->nowait);
+
+ if (p->search_commit_root) {
+ BUG_ON(time_seq);
+ return btrfs_search_slot(NULL, root, key, p, 0, 0);
+ }
+
+again:
+ b = btrfs_get_old_root(root, time_seq);
+ if (!b) {
+ ret = -EIO;
+ goto done;
+ }
+ level = btrfs_header_level(b);
+ p->locks[level] = BTRFS_READ_LOCK;
+
+ while (b) {
+ int dec = 0;
+
+ level = btrfs_header_level(b);
+ p->nodes[level] = b;
+
+ /*
+ * 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.
+ */
+ btrfs_unlock_up_safe(p, level + 1);
+
+ ret = btrfs_bin_search(b, key, &slot);
+ if (ret < 0)
+ goto done;
+
+ if (level == 0) {
+ p->slots[level] = slot;
+ unlock_up(p, level, lowest_unlock, 0, NULL);
+ goto done;
+ }
+
+ if (ret && slot > 0) {
+ dec = 1;
+ slot--;
+ }
+ p->slots[level] = slot;
+ unlock_up(p, level, lowest_unlock, 0, NULL);
+
+ if (level == lowest_level) {
+ if (dec)
+ p->slots[level]++;
+ goto done;
+ }
+
+ err = read_block_for_search(root, p, &b, level, slot, key);
+ if (err == -EAGAIN)
+ goto again;
+ if (err) {
+ ret = err;
+ goto done;
+ }
+
+ level = btrfs_header_level(b);
+ btrfs_tree_read_lock(b);
+ b = btrfs_tree_mod_log_rewind(fs_info, p, b, time_seq);
+ if (!b) {
+ ret = -ENOMEM;
+ goto done;
+ }
+ p->locks[level] = BTRFS_READ_LOCK;
+ p->nodes[level] = b;
+ }
+ ret = 1;
+done:
+ if (ret < 0)
+ btrfs_release_path(p);
+
+ return ret;
+}
+
+/*
+ * helper to use instead of search slot if no exact match is needed but
+ * instead the next or previous item should be returned.
+ * When find_higher is true, the next higher item is returned, the next lower
+ * otherwise.
+ * When return_any and find_higher are both true, and no higher item is found,
+ * return the next lower instead.
+ * When return_any is true and find_higher is false, and no lower item is found,
+ * return the next higher instead.
+ * It returns 0 if any item is found, 1 if none is found (tree empty), and
+ * < 0 on error
+ */
+int btrfs_search_slot_for_read(struct btrfs_root *root,
+ const struct btrfs_key *key,
+ struct btrfs_path *p, int find_higher,
+ int return_any)
+{
+ int ret;
+ struct extent_buffer *leaf;
+
+again:
+ ret = btrfs_search_slot(NULL, root, key, p, 0, 0);
+ if (ret <= 0)
+ return ret;
+ /*
+ * a return value of 1 means the path is at the position where the
+ * item should be inserted. Normally this is the next bigger item,
+ * but in case the previous item is the last in a leaf, path points
+ * to the first free slot in the previous leaf, i.e. at an invalid
+ * item.
+ */
+ leaf = p->nodes[0];
+
+ if (find_higher) {
+ if (p->slots[0] >= btrfs_header_nritems(leaf)) {
+ ret = btrfs_next_leaf(root, p);
+ if (ret <= 0)
+ return ret;
+ if (!return_any)
+ return 1;
+ /*
+ * no higher item found, return the next
+ * lower instead
+ */
+ return_any = 0;
+ find_higher = 0;
+ btrfs_release_path(p);
+ goto again;
+ }
+ } else {
+ if (p->slots[0] == 0) {
+ ret = btrfs_prev_leaf(root, p);
+ if (ret < 0)
+ return ret;
+ if (!ret) {
+ leaf = p->nodes[0];
+ if (p->slots[0] == btrfs_header_nritems(leaf))
+ p->slots[0]--;
+ return 0;
+ }
+ if (!return_any)
+ return 1;
+ /*
+ * no lower item found, return the next
+ * higher instead
+ */
+ return_any = 0;
+ find_higher = 1;
+ btrfs_release_path(p);
+ goto again;
+ } else {
+ --p->slots[0];
+ }
+ }
+ return 0;
+}
+
+/*
+ * Execute search and call btrfs_previous_item to traverse backwards if the item
+ * was not found.
+ *
+ * Return 0 if found, 1 if not found and < 0 if error.
+ */
+int btrfs_search_backwards(struct btrfs_root *root, struct btrfs_key *key,
+ struct btrfs_path *path)
+{
+ int ret;
+
+ ret = btrfs_search_slot(NULL, root, key, path, 0, 0);
+ if (ret > 0)
+ ret = btrfs_previous_item(root, path, key->objectid, key->type);
+
+ if (ret == 0)
+ btrfs_item_key_to_cpu(path->nodes[0], key, path->slots[0]);
+
+ return ret;
+}
+
+/**
+ * Search for a valid slot for the given path.
+ *
+ * @root: The root node of the tree.
+ * @key: Will contain a valid item if found.
+ * @path: The starting point to validate the slot.
+ *
+ * Return: 0 if the item is valid
+ * 1 if not found
+ * <0 if error.
+ */
+int btrfs_get_next_valid_item(struct btrfs_root *root, struct btrfs_key *key,
+ struct btrfs_path *path)
+{
+ while (1) {
+ int ret;
+ const int slot = path->slots[0];
+ const struct extent_buffer *leaf = path->nodes[0];
+
+ /* This is where we start walking the path. */
+ if (slot >= btrfs_header_nritems(leaf)) {
+ /*
+ * If we've reached the last slot in this leaf we need
+ * to go to the next leaf and reset the path.
+ */
+ ret = btrfs_next_leaf(root, path);
+ if (ret)
+ return ret;
+ continue;
+ }
+ /* Store the found, valid item in @key. */
+ btrfs_item_key_to_cpu(leaf, key, slot);
+ break;
+ }
+ return 0;
+}
+
+/*
+ * 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
+ *
+ */
+static void fixup_low_keys(struct btrfs_path *path,
+ struct btrfs_disk_key *key, int level)
+{
+ int i;
+ struct extent_buffer *t;
+ int ret;
+
+ for (i = level; i < BTRFS_MAX_LEVEL; i++) {
+ int tslot = path->slots[i];
+
+ if (!path->nodes[i])
+ break;
+ t = path->nodes[i];
+ ret = btrfs_tree_mod_log_insert_key(t, tslot,
+ BTRFS_MOD_LOG_KEY_REPLACE, GFP_ATOMIC);
+ BUG_ON(ret < 0);
+ btrfs_set_node_key(t, key, tslot);
+ btrfs_mark_buffer_dirty(path->nodes[i]);
+ if (tslot != 0)
+ break;
+ }
+}
+
+/*
+ * update item key.
+ *
+ * This function isn't completely safe. It's the caller's responsibility
+ * that the new key won't break the order
+ */
+void btrfs_set_item_key_safe(struct btrfs_fs_info *fs_info,
+ struct btrfs_path *path,
+ const 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 (unlikely(comp_keys(&disk_key, new_key) >= 0)) {
+ btrfs_crit(fs_info,
+ "slot %u key (%llu %u %llu) new key (%llu %u %llu)",
+ slot, btrfs_disk_key_objectid(&disk_key),
+ btrfs_disk_key_type(&disk_key),
+ btrfs_disk_key_offset(&disk_key),
+ new_key->objectid, new_key->type,
+ new_key->offset);
+ btrfs_print_leaf(eb);
+ BUG();
+ }
+ }
+ if (slot < btrfs_header_nritems(eb) - 1) {
+ btrfs_item_key(eb, &disk_key, slot + 1);
+ if (unlikely(comp_keys(&disk_key, new_key) <= 0)) {
+ btrfs_crit(fs_info,
+ "slot %u key (%llu %u %llu) new key (%llu %u %llu)",
+ slot, btrfs_disk_key_objectid(&disk_key),
+ btrfs_disk_key_type(&disk_key),
+ btrfs_disk_key_offset(&disk_key),
+ new_key->objectid, new_key->type,
+ new_key->offset);
+ btrfs_print_leaf(eb);
+ BUG();
+ }
+ }
+
+ 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(path, &disk_key, 1);
+}
+
+/*
+ * Check key order of two sibling extent buffers.
+ *
+ * Return true if something is wrong.
+ * Return false if everything is fine.
+ *
+ * Tree-checker only works inside one tree block, thus the following
+ * corruption can not be detected by tree-checker:
+ *
+ * Leaf @left | Leaf @right
+ * --------------------------------------------------------------
+ * | 1 | 2 | 3 | 4 | 5 | f6 | | 7 | 8 |
+ *
+ * Key f6 in leaf @left itself is valid, but not valid when the next
+ * key in leaf @right is 7.
+ * This can only be checked at tree block merge time.
+ * And since tree checker has ensured all key order in each tree block
+ * is correct, we only need to bother the last key of @left and the first
+ * key of @right.
+ */
+static bool check_sibling_keys(struct extent_buffer *left,
+ struct extent_buffer *right)
+{
+ struct btrfs_key left_last;
+ struct btrfs_key right_first;
+ int level = btrfs_header_level(left);
+ int nr_left = btrfs_header_nritems(left);
+ int nr_right = btrfs_header_nritems(right);
+
+ /* No key to check in one of the tree blocks */
+ if (!nr_left || !nr_right)
+ return false;
+
+ if (level) {
+ btrfs_node_key_to_cpu(left, &left_last, nr_left - 1);
+ btrfs_node_key_to_cpu(right, &right_first, 0);
+ } else {
+ btrfs_item_key_to_cpu(left, &left_last, nr_left - 1);
+ btrfs_item_key_to_cpu(right, &right_first, 0);
+ }
+
+ if (btrfs_comp_cpu_keys(&left_last, &right_first) >= 0) {
+ btrfs_crit(left->fs_info,
+"bad key order, sibling blocks, left last (%llu %u %llu) right first (%llu %u %llu)",
+ left_last.objectid, left_last.type,
+ left_last.offset, right_first.objectid,
+ right_first.type, right_first.offset);
+ return true;
+ }
+ return false;
+}
+
+/*
+ * 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 extent_buffer *dst,
+ struct extent_buffer *src, int empty)
+{
+ struct btrfs_fs_info *fs_info = trans->fs_info;
+ 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(fs_info) - 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);
+
+ /* dst is the left eb, src is the middle eb */
+ if (check_sibling_keys(dst, src)) {
+ ret = -EUCLEAN;
+ btrfs_abort_transaction(trans, ret);
+ return ret;
+ }
+ ret = btrfs_tree_mod_log_eb_copy(dst, src, dst_nritems, 0, push_items);
+ if (ret) {
+ btrfs_abort_transaction(trans, ret);
+ return ret;
+ }
+ 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) {
+ /*
+ * Don't call btrfs_tree_mod_log_insert_move() here, key removal
+ * was already fully logged by btrfs_tree_mod_log_eb_copy() above.
+ */
+ 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 extent_buffer *dst,
+ struct extent_buffer *src)
+{
+ struct btrfs_fs_info *fs_info = trans->fs_info;
+ 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(fs_info) - 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;
+
+ /* dst is the right eb, src is the middle eb */
+ if (check_sibling_keys(src, dst)) {
+ ret = -EUCLEAN;
+ btrfs_abort_transaction(trans, ret);
+ return ret;
+ }
+ ret = btrfs_tree_mod_log_insert_move(dst, push_items, 0, dst_nritems);
+ BUG_ON(ret < 0);
+ memmove_extent_buffer(dst, btrfs_node_key_ptr_offset(push_items),
+ btrfs_node_key_ptr_offset(0),
+ (dst_nritems) *
+ sizeof(struct btrfs_key_ptr));
+
+ ret = btrfs_tree_mod_log_eb_copy(dst, src, 0, src_nritems - push_items,
+ push_items);
+ if (ret) {
+ btrfs_abort_transaction(trans, ret);
+ return ret;
+ }
+ 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)
+{
+ struct btrfs_fs_info *fs_info = root->fs_info;
+ u64 lower_gen;
+ struct extent_buffer *lower;
+ struct extent_buffer *c;
+ struct extent_buffer *old;
+ struct btrfs_disk_key lower_key;
+ int ret;
+
+ 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_tree_block(trans, root, 0, root->root_key.objectid,
+ &lower_key, level, root->node->start, 0,
+ BTRFS_NESTING_NEW_ROOT);
+ if (IS_ERR(c))
+ return PTR_ERR(c);
+
+ root_add_used(root, fs_info->nodesize);
+
+ btrfs_set_header_nritems(c, 1);
+ 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;
+ ret = btrfs_tree_mod_log_insert_root(root->node, c, false);
+ BUG_ON(ret < 0);
+ 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);
+ atomic_inc(&c->refs);
+ 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.
+ */
+static void insert_ptr(struct btrfs_trans_handle *trans,
+ struct btrfs_path *path,
+ struct btrfs_disk_key *key, u64 bytenr,
+ int slot, int level)
+{
+ struct extent_buffer *lower;
+ int nritems;
+ int ret;
+
+ BUG_ON(!path->nodes[level]);
+ btrfs_assert_tree_write_locked(path->nodes[level]);
+ lower = path->nodes[level];
+ nritems = btrfs_header_nritems(lower);
+ BUG_ON(slot > nritems);
+ BUG_ON(nritems == BTRFS_NODEPTRS_PER_BLOCK(trans->fs_info));
+ if (slot != nritems) {
+ if (level) {
+ ret = btrfs_tree_mod_log_insert_move(lower, slot + 1,
+ slot, nritems - slot);
+ BUG_ON(ret < 0);
+ }
+ memmove_extent_buffer(lower,
+ btrfs_node_key_ptr_offset(slot + 1),
+ btrfs_node_key_ptr_offset(slot),
+ (nritems - slot) * sizeof(struct btrfs_key_ptr));
+ }
+ if (level) {
+ ret = btrfs_tree_mod_log_insert_key(lower, slot,
+ BTRFS_MOD_LOG_KEY_ADD, GFP_NOFS);
+ BUG_ON(ret < 0);
+ }
+ 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);
+}
+
+/*
+ * 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 btrfs_fs_info *fs_info = root->fs_info;
+ struct extent_buffer *c;
+ struct extent_buffer *split;
+ struct btrfs_disk_key disk_key;
+ int mid;
+ int ret;
+ 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
+ *
+ * tree mod log: We don't log_removal old root in
+ * insert_new_root, because that root buffer will be kept as a
+ * normal node. We are going to log removal of half of the
+ * elements below with btrfs_tree_mod_log_eb_copy(). We're
+ * holding a tree lock on the buffer, which is why we cannot
+ * race with other tree_mod_log users.
+ */
+ 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(fs_info) - 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_tree_block(trans, root, 0, root->root_key.objectid,
+ &disk_key, level, c->start, 0,
+ BTRFS_NESTING_SPLIT);
+ if (IS_ERR(split))
+ return PTR_ERR(split);
+
+ root_add_used(root, fs_info->nodesize);
+ ASSERT(btrfs_header_level(c) == level);
+
+ ret = btrfs_tree_mod_log_eb_copy(split, c, 0, mid, c_nritems - mid);
+ if (ret) {
+ btrfs_tree_unlock(split);
+ free_extent_buffer(split);
+ btrfs_abort_transaction(trans, ret);
+ return ret;
+ }
+ 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);
+
+ btrfs_mark_buffer_dirty(c);
+ btrfs_mark_buffer_dirty(split);
+
+ insert_ptr(trans, path, &disk_key, split->start,
+ path->slots[level + 1] + 1, level + 1);
+
+ 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 0;
+}
+
+/*
+ * 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_offset(l, start) + btrfs_item_size(l, start);
+ data_len = data_len - btrfs_item_offset(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 extent_buffer *leaf)
+{
+ struct btrfs_fs_info *fs_info = leaf->fs_info;
+ int nritems = btrfs_header_nritems(leaf);
+ int ret;
+
+ ret = BTRFS_LEAF_DATA_SIZE(fs_info) - leaf_space_used(leaf, 0, nritems);
+ if (ret < 0) {
+ btrfs_crit(fs_info,
+ "leaf free space ret %d, leaf data size %lu, used %d nritems %d",
+ ret,
+ (unsigned long) BTRFS_LEAF_DATA_SIZE(fs_info),
+ 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_path *path,
+ int data_size, int empty,
+ struct extent_buffer *right,
+ int free_space, u32 left_nritems,
+ u32 min_slot)
+{
+ struct btrfs_fs_info *fs_info = right->fs_info;
+ struct extent_buffer *left = path->nodes[0];
+ struct extent_buffer *upper = path->nodes[1];
+ struct btrfs_map_token token;
+ struct btrfs_disk_key disk_key;
+ int slot;
+ u32 i;
+ int push_space = 0;
+ int push_items = 0;
+ 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) {
+ if (!empty && push_items > 0) {
+ if (path->slots[0] > i)
+ break;
+ if (path->slots[0] == i) {
+ int space = btrfs_leaf_free_space(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, i);
+ if (this_item_size + sizeof(struct btrfs_item) +
+ push_space > free_space)
+ break;
+
+ push_items++;
+ push_space += this_item_size + sizeof(struct btrfs_item);
+ if (i == 0)
+ break;
+ i--;
+ }
+
+ if (push_items == 0)
+ goto out_unlock;
+
+ WARN_ON(!empty && push_items == left_nritems);
+
+ /* push left to right */
+ right_nritems = btrfs_header_nritems(right);
+
+ push_space = btrfs_item_data_end(left, left_nritems - push_items);
+ push_space -= leaf_data_end(left);
+
+ /* make room in the right data area */
+ data_end = leaf_data_end(right);
+ memmove_extent_buffer(right,
+ BTRFS_LEAF_DATA_OFFSET + data_end - push_space,
+ BTRFS_LEAF_DATA_OFFSET + data_end,
+ BTRFS_LEAF_DATA_SIZE(fs_info) - data_end);
+
+ /* copy from the left data area */
+ copy_extent_buffer(right, left, BTRFS_LEAF_DATA_OFFSET +
+ BTRFS_LEAF_DATA_SIZE(fs_info) - push_space,
+ BTRFS_LEAF_DATA_OFFSET + leaf_data_end(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 */
+ btrfs_init_map_token(&token, right);
+ right_nritems += push_items;
+ btrfs_set_header_nritems(right, right_nritems);
+ push_space = BTRFS_LEAF_DATA_SIZE(fs_info);
+ for (i = 0; i < right_nritems; i++) {
+ push_space -= btrfs_token_item_size(&token, i);
+ btrfs_set_token_item_offset(&token, i, push_space);
+ }
+
+ left_nritems -= push_items;
+ btrfs_set_header_nritems(left, left_nritems);
+
+ if (left_nritems)
+ btrfs_mark_buffer_dirty(left);
+ else
+ btrfs_clean_tree_block(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)
+ btrfs_clean_tree_block(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_write_locked(path->nodes[1]);
+
+ right = btrfs_read_node_slot(upper, slot + 1);
+ /*
+ * slot + 1 is not valid or we fail to read the right node,
+ * no big deal, just return.
+ */
+ if (IS_ERR(right))
+ return 1;
+
+ __btrfs_tree_lock(right, BTRFS_NESTING_RIGHT);
+
+ free_space = btrfs_leaf_free_space(right);
+ if (free_space < data_size)
+ goto out_unlock;
+
+ ret = btrfs_cow_block(trans, root, right, upper,
+ slot + 1, &right, BTRFS_NESTING_RIGHT_COW);
+ if (ret)
+ goto out_unlock;
+
+ left_nritems = btrfs_header_nritems(left);
+ if (left_nritems == 0)
+ goto out_unlock;
+
+ if (check_sibling_keys(left, right)) {
+ ret = -EUCLEAN;
+ btrfs_abort_transaction(trans, ret);
+ btrfs_tree_unlock(right);
+ free_extent_buffer(right);
+ return ret;
+ }
+ if (path->slots[0] == left_nritems && !empty) {
+ /* Key greater than all keys in the leaf, right neighbor has
+ * enough room for it and we're not emptying our leaf to delete
+ * it, therefore use right neighbor to insert the new item and
+ * no need to touch/dirty our left leaf. */
+ btrfs_tree_unlock(left);
+ free_extent_buffer(left);
+ path->nodes[0] = right;
+ path->slots[0] = 0;
+ path->slots[1]++;
+ return 0;
+ }
+
+ return __push_leaf_right(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_path *path, int data_size,
+ int empty, struct extent_buffer *left,
+ int free_space, u32 right_nritems,
+ u32 max_slot)
+{
+ struct btrfs_fs_info *fs_info = left->fs_info;
+ struct btrfs_disk_key disk_key;
+ struct extent_buffer *right = path->nodes[0];
+ int i;
+ int push_space = 0;
+ int push_items = 0;
+ u32 old_left_nritems;
+ u32 nr;
+ int ret = 0;
+ u32 this_item_size;
+ u32 old_left_item_size;
+ struct btrfs_map_token token;
+
+ if (empty)
+ nr = min(right_nritems, max_slot);
+ else
+ nr = min(right_nritems - 1, max_slot);
+
+ for (i = 0; i < nr; i++) {
+ if (!empty && push_items > 0) {
+ if (path->slots[0] < i)
+ break;
+ if (path->slots[0] == i) {
+ int space = btrfs_leaf_free_space(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, i);
+ if (this_item_size + sizeof(struct btrfs_item) + push_space >
+ free_space)
+ break;
+
+ push_items++;
+ push_space += this_item_size + sizeof(struct btrfs_item);
+ }
+
+ if (push_items == 0) {
+ ret = 1;
+ goto out;
+ }
+ WARN_ON(!empty && push_items == btrfs_header_nritems(right));
+
+ /* 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(fs_info) -
+ btrfs_item_offset(right, push_items - 1);
+
+ copy_extent_buffer(left, right, BTRFS_LEAF_DATA_OFFSET +
+ leaf_data_end(left) - push_space,
+ BTRFS_LEAF_DATA_OFFSET +
+ btrfs_item_offset(right, push_items - 1),
+ push_space);
+ old_left_nritems = btrfs_header_nritems(left);
+ BUG_ON(old_left_nritems <= 0);
+
+ btrfs_init_map_token(&token, left);
+ old_left_item_size = btrfs_item_offset(left, old_left_nritems - 1);
+ for (i = old_left_nritems; i < old_left_nritems + push_items; i++) {
+ u32 ioff;
+
+ ioff = btrfs_token_item_offset(&token, i);
+ btrfs_set_token_item_offset(&token, i,
+ ioff - (BTRFS_LEAF_DATA_SIZE(fs_info) - old_left_item_size));
+ }
+ btrfs_set_header_nritems(left, old_left_nritems + push_items);
+
+ /* fixup right node */
+ if (push_items > right_nritems)
+ WARN(1, KERN_CRIT "push items %d nr %u\n", push_items,
+ right_nritems);
+
+ if (push_items < right_nritems) {
+ push_space = btrfs_item_offset(right, push_items - 1) -
+ leaf_data_end(right);
+ memmove_extent_buffer(right, BTRFS_LEAF_DATA_OFFSET +
+ BTRFS_LEAF_DATA_SIZE(fs_info) - push_space,
+ BTRFS_LEAF_DATA_OFFSET +
+ leaf_data_end(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));
+ }
+
+ btrfs_init_map_token(&token, right);
+ right_nritems -= push_items;
+ btrfs_set_header_nritems(right, right_nritems);
+ push_space = BTRFS_LEAF_DATA_SIZE(fs_info);
+ for (i = 0; i < right_nritems; i++) {
+ push_space = push_space - btrfs_token_item_size(&token, i);
+ btrfs_set_token_item_offset(&token, i, push_space);
+ }
+
+ btrfs_mark_buffer_dirty(left);
+ if (right_nritems)
+ btrfs_mark_buffer_dirty(right);
+ else
+ btrfs_clean_tree_block(right);
+
+ btrfs_item_key(right, &disk_key, 0);
+ fixup_low_keys(path, &disk_key, 1);
+
+ /* 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_write_locked(path->nodes[1]);
+
+ left = btrfs_read_node_slot(path->nodes[1], slot - 1);
+ /*
+ * slot - 1 is not valid or we fail to read the left node,
+ * no big deal, just return.
+ */
+ if (IS_ERR(left))
+ return 1;
+
+ __btrfs_tree_lock(left, BTRFS_NESTING_LEFT);
+
+ free_space = btrfs_leaf_free_space(left);
+ if (free_space < data_size) {
+ ret = 1;
+ goto out;
+ }
+
+ ret = btrfs_cow_block(trans, root, left,
+ path->nodes[1], slot - 1, &left,
+ BTRFS_NESTING_LEFT_COW);
+ if (ret) {
+ /* we hit -ENOSPC, but it isn't fatal here */
+ if (ret == -ENOSPC)
+ ret = 1;
+ goto out;
+ }
+
+ if (check_sibling_keys(left, right)) {
+ ret = -EUCLEAN;
+ btrfs_abort_transaction(trans, ret);
+ goto out;
+ }
+ return __push_leaf_left(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.
+ */
+static noinline void copy_for_split(struct btrfs_trans_handle *trans,
+ struct btrfs_path *path,
+ struct extent_buffer *l,
+ struct extent_buffer *right,
+ int slot, int mid, int nritems)
+{
+ struct btrfs_fs_info *fs_info = trans->fs_info;
+ int data_copy_size;
+ int rt_data_off;
+ int i;
+ struct btrfs_disk_key disk_key;
+ struct btrfs_map_token token;
+
+ nritems = nritems - mid;
+ btrfs_set_header_nritems(right, nritems);
+ data_copy_size = btrfs_item_data_end(l, mid) - leaf_data_end(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_OFFSET + BTRFS_LEAF_DATA_SIZE(fs_info) -
+ data_copy_size, BTRFS_LEAF_DATA_OFFSET +
+ leaf_data_end(l), data_copy_size);
+
+ rt_data_off = BTRFS_LEAF_DATA_SIZE(fs_info) - btrfs_item_data_end(l, mid);
+
+ btrfs_init_map_token(&token, right);
+ for (i = 0; i < nritems; i++) {
+ u32 ioff;
+
+ ioff = btrfs_token_item_offset(&token, i);
+ btrfs_set_token_item_offset(&token, i, ioff + rt_data_off);
+ }
+
+ btrfs_set_header_nritems(l, mid);
+ btrfs_item_key(right, &disk_key, 0);
+ insert_ptr(trans, path, &disk_key, right->start, path->slots[1] + 1, 1);
+
+ 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);
+}
+
+/*
+ * 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;
+ int space_needed = data_size;
+
+ slot = path->slots[0];
+ if (slot < btrfs_header_nritems(path->nodes[0]))
+ space_needed -= btrfs_leaf_free_space(path->nodes[0]);
+
+ /*
+ * try to push all the items after our slot into the
+ * right leaf
+ */
+ ret = push_leaf_right(trans, root, path, 1, space_needed, 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(path->nodes[0]) >= data_size)
+ return 0;
+
+ /* try to push all the items before our slot into the next leaf */
+ slot = path->slots[0];
+ space_needed = data_size;
+ if (slot > 0)
+ space_needed -= btrfs_leaf_free_space(path->nodes[0]);
+ ret = push_leaf_left(trans, root, path, 1, space_needed, 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,
+ const 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;
+ struct btrfs_fs_info *fs_info = root->fs_info;
+ 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(l, slot) +
+ sizeof(struct btrfs_item) > BTRFS_LEAF_DATA_SIZE(fs_info))
+ return -EOVERFLOW;
+
+ /* first try to make some room by pushing left and right */
+ if (data_size && path->nodes[1]) {
+ int space_needed = data_size;
+
+ if (slot < btrfs_header_nritems(l))
+ space_needed -= btrfs_leaf_free_space(l);
+
+ wret = push_leaf_right(trans, root, path, space_needed,
+ space_needed, 0, 0);
+ if (wret < 0)
+ return wret;
+ if (wret) {
+ space_needed = data_size;
+ if (slot > 0)
+ space_needed -= btrfs_leaf_free_space(l);
+ wret = push_leaf_left(trans, root, path, space_needed,
+ space_needed, 0, (u32)-1);
+ if (wret < 0)
+ return wret;
+ }
+ l = path->nodes[0];
+
+ /* did the pushes work? */
+ if (btrfs_leaf_free_space(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(fs_info)) {
+ if (slot >= nritems) {
+ split = 0;
+ } else {
+ mid = slot;
+ if (mid != nritems &&
+ leaf_space_used(l, mid, nritems - mid) +
+ data_size > BTRFS_LEAF_DATA_SIZE(fs_info)) {
+ 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(fs_info)) {
+ 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(fs_info)) {
+ 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);
+
+ /*
+ * We have to about BTRFS_NESTING_NEW_ROOT here if we've done a double
+ * split, because we're only allowed to have MAX_LOCKDEP_SUBCLASSES
+ * subclasses, which is 8 at the time of this patch, and we've maxed it
+ * out. In the future we could add a
+ * BTRFS_NESTING_SPLIT_THE_SPLITTENING if we need to, but for now just
+ * use BTRFS_NESTING_NEW_ROOT.
+ */
+ right = btrfs_alloc_tree_block(trans, root, 0, root->root_key.objectid,
+ &disk_key, 0, l->start, 0,
+ num_doubles ? BTRFS_NESTING_NEW_ROOT :
+ BTRFS_NESTING_SPLIT);
+ if (IS_ERR(right))
+ return PTR_ERR(right);
+
+ root_add_used(root, fs_info->nodesize);
+
+ if (split == 0) {
+ if (mid <= slot) {
+ btrfs_set_header_nritems(right, 0);
+ insert_ptr(trans, path, &disk_key,
+ right->start, path->slots[1] + 1, 1);
+ 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);
+ insert_ptr(trans, path, &disk_key,
+ right->start, path->slots[1], 1);
+ 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)
+ fixup_low_keys(path, &disk_key, 1);
+ }
+ /*
+ * We create a new leaf 'right' for the required ins_len and
+ * we'll do btrfs_mark_buffer_dirty() on this leaf after copying
+ * the content of ins_len to 'right'.
+ */
+ return ret;
+ }
+
+ copy_for_split(trans, path, l, right, slot, mid, nritems);
+
+ if (split == 2) {
+ BUG_ON(num_doubles != 0);
+ num_doubles++;
+ goto again;
+ }
+
+ return 0;
+
+push_for_double:
+ push_for_double_split(trans, root, path, data_size);
+ tried_avoid_double = 1;
+ if (btrfs_leaf_free_space(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(leaf) >= ins_len)
+ return 0;
+
+ item_size = btrfs_item_size(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)
+ ret = -EAGAIN;
+ if (ret < 0)
+ goto err;
+
+ ret = -EAGAIN;
+ leaf = path->nodes[0];
+ /* if our item isn't there, return now */
+ if (item_size != btrfs_item_size(leaf, path->slots[0]))
+ goto err;
+
+ /* the leaf has changed, it now has room. return now */
+ if (btrfs_leaf_free_space(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;
+ }
+
+ 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_path *path,
+ const struct btrfs_key *new_key,
+ unsigned long split_offset)
+{
+ struct extent_buffer *leaf;
+ int orig_slot, 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(leaf) < sizeof(struct btrfs_item));
+
+ orig_slot = path->slots[0];
+ orig_offset = btrfs_item_offset(leaf, path->slots[0]);
+ item_size = btrfs_item_size(leaf, path->slots[0]);
+
+ 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);
+
+ btrfs_set_item_offset(leaf, slot, orig_offset);
+ btrfs_set_item_size(leaf, slot, item_size - split_offset);
+
+ btrfs_set_item_offset(leaf, orig_slot,
+ orig_offset + item_size - split_offset);
+ btrfs_set_item_size(leaf, orig_slot, 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(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,
+ const 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(path, new_key, split_offset);
+ return ret;
+}
+
+/*
+ * 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.
+ */
+void btrfs_truncate_item(struct btrfs_path *path, u32 new_size, int from_end)
+{
+ int slot;
+ struct extent_buffer *leaf;
+ u32 nritems;
+ unsigned int data_end;
+ unsigned int old_data_start;
+ unsigned int old_size;
+ unsigned int size_diff;
+ int i;
+ struct btrfs_map_token token;
+
+ leaf = path->nodes[0];
+ slot = path->slots[0];
+
+ old_size = btrfs_item_size(leaf, slot);
+ if (old_size == new_size)
+ return;
+
+ nritems = btrfs_header_nritems(leaf);
+ data_end = leaf_data_end(leaf);
+
+ old_data_start = btrfs_item_offset(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 */
+ btrfs_init_map_token(&token, leaf);
+ for (i = slot; i < nritems; i++) {
+ u32 ioff;
+
+ ioff = btrfs_token_item_offset(&token, i);
+ btrfs_set_token_item_offset(&token, i, ioff + size_diff);
+ }
+
+ /* shift the data */
+ if (from_end) {
+ memmove_extent_buffer(leaf, BTRFS_LEAF_DATA_OFFSET +
+ data_end + size_diff, BTRFS_LEAF_DATA_OFFSET +
+ 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,
+ BTRFS_FILE_EXTENT_INLINE_DATA_START);
+ }
+ }
+
+ memmove_extent_buffer(leaf, BTRFS_LEAF_DATA_OFFSET +
+ data_end + size_diff, BTRFS_LEAF_DATA_OFFSET +
+ 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(path, &disk_key, 1);
+ }
+
+ btrfs_set_item_size(leaf, slot, new_size);
+ btrfs_mark_buffer_dirty(leaf);
+
+ if (btrfs_leaf_free_space(leaf) < 0) {
+ btrfs_print_leaf(leaf);
+ BUG();
+ }
+}
+
+/*
+ * make the item pointed to by the path bigger, data_size is the added size.
+ */
+void btrfs_extend_item(struct btrfs_path *path, u32 data_size)
+{
+ int slot;
+ struct extent_buffer *leaf;
+ u32 nritems;
+ unsigned int data_end;
+ unsigned int old_data;
+ unsigned int old_size;
+ int i;
+ struct btrfs_map_token token;
+
+ leaf = path->nodes[0];
+
+ nritems = btrfs_header_nritems(leaf);
+ data_end = leaf_data_end(leaf);
+
+ if (btrfs_leaf_free_space(leaf) < data_size) {
+ btrfs_print_leaf(leaf);
+ BUG();
+ }
+ slot = path->slots[0];
+ old_data = btrfs_item_data_end(leaf, slot);
+
+ BUG_ON(slot < 0);
+ if (slot >= nritems) {
+ btrfs_print_leaf(leaf);
+ btrfs_crit(leaf->fs_info, "slot %d too large, nritems %d",
+ slot, nritems);
+ BUG();
+ }
+
+ /*
+ * item0..itemN ... dataN.offset..dataN.size .. data0.size
+ */
+ /* first correct the data pointers */
+ btrfs_init_map_token(&token, leaf);
+ for (i = slot; i < nritems; i++) {
+ u32 ioff;
+
+ ioff = btrfs_token_item_offset(&token, i);
+ btrfs_set_token_item_offset(&token, i, ioff - data_size);
+ }
+
+ /* shift the data */
+ memmove_extent_buffer(leaf, BTRFS_LEAF_DATA_OFFSET +
+ data_end - data_size, BTRFS_LEAF_DATA_OFFSET +
+ data_end, old_data - data_end);
+
+ data_end = old_data;
+ old_size = btrfs_item_size(leaf, slot);
+ btrfs_set_item_size(leaf, slot, old_size + data_size);
+ btrfs_mark_buffer_dirty(leaf);
+
+ if (btrfs_leaf_free_space(leaf) < 0) {
+ btrfs_print_leaf(leaf);
+ BUG();
+ }
+}
+
+/**
+ * setup_items_for_insert - Helper called before inserting one or more items
+ * to a leaf. Main purpose is to save stack depth by doing the bulk of the work
+ * in a function that doesn't call btrfs_search_slot
+ *
+ * @root: root we are inserting items to
+ * @path: points to the leaf/slot where we are going to insert new items
+ * @batch: information about the batch of items to insert
+ */
+static void setup_items_for_insert(struct btrfs_root *root, struct btrfs_path *path,
+ const struct btrfs_item_batch *batch)
+{
+ struct btrfs_fs_info *fs_info = root->fs_info;
+ int i;
+ u32 nritems;
+ unsigned int data_end;
+ struct btrfs_disk_key disk_key;
+ struct extent_buffer *leaf;
+ int slot;
+ struct btrfs_map_token token;
+ u32 total_size;
+
+ /*
+ * Before anything else, update keys in the parent and other ancestors
+ * if needed, then release the write locks on them, so that other tasks
+ * can use them while we modify the leaf.
+ */
+ if (path->slots[0] == 0) {
+ btrfs_cpu_key_to_disk(&disk_key, &batch->keys[0]);
+ fixup_low_keys(path, &disk_key, 1);
+ }
+ btrfs_unlock_up_safe(path, 1);
+
+ leaf = path->nodes[0];
+ slot = path->slots[0];
+
+ nritems = btrfs_header_nritems(leaf);
+ data_end = leaf_data_end(leaf);
+ total_size = batch->total_data_size + (batch->nr * sizeof(struct btrfs_item));
+
+ if (btrfs_leaf_free_space(leaf) < total_size) {
+ btrfs_print_leaf(leaf);
+ btrfs_crit(fs_info, "not enough freespace need %u have %d",
+ total_size, btrfs_leaf_free_space(leaf));
+ BUG();
+ }
+
+ btrfs_init_map_token(&token, leaf);
+ if (slot != nritems) {
+ unsigned int old_data = btrfs_item_data_end(leaf, slot);
+
+ if (old_data < data_end) {
+ btrfs_print_leaf(leaf);
+ btrfs_crit(fs_info,
+ "item at slot %d with data offset %u beyond data end of leaf %u",
+ slot, old_data, data_end);
+ BUG();
+ }
+ /*
+ * item0..itemN ... dataN.offset..dataN.size .. data0.size
+ */
+ /* first correct the data pointers */
+ for (i = slot; i < nritems; i++) {
+ u32 ioff;
+
+ ioff = btrfs_token_item_offset(&token, i);
+ btrfs_set_token_item_offset(&token, i,
+ ioff - batch->total_data_size);
+ }
+ /* shift the items */
+ memmove_extent_buffer(leaf, btrfs_item_nr_offset(slot + batch->nr),
+ btrfs_item_nr_offset(slot),
+ (nritems - slot) * sizeof(struct btrfs_item));
+
+ /* shift the data */
+ memmove_extent_buffer(leaf, BTRFS_LEAF_DATA_OFFSET +
+ data_end - batch->total_data_size,
+ BTRFS_LEAF_DATA_OFFSET + data_end,
+ old_data - data_end);
+ data_end = old_data;
+ }
+
+ /* setup the item for the new data */
+ for (i = 0; i < batch->nr; i++) {
+ btrfs_cpu_key_to_disk(&disk_key, &batch->keys[i]);
+ btrfs_set_item_key(leaf, &disk_key, slot + i);
+ data_end -= batch->data_sizes[i];
+ btrfs_set_token_item_offset(&token, slot + i, data_end);
+ btrfs_set_token_item_size(&token, slot + i, batch->data_sizes[i]);
+ }
+
+ btrfs_set_header_nritems(leaf, nritems + batch->nr);
+ btrfs_mark_buffer_dirty(leaf);
+
+ if (btrfs_leaf_free_space(leaf) < 0) {
+ btrfs_print_leaf(leaf);
+ BUG();
+ }
+}
+
+/*
+ * Insert a new item into a leaf.
+ *
+ * @root: The root of the btree.
+ * @path: A path pointing to the target leaf and slot.
+ * @key: The key of the new item.
+ * @data_size: The size of the data associated with the new key.
+ */
+void btrfs_setup_item_for_insert(struct btrfs_root *root,
+ struct btrfs_path *path,
+ const struct btrfs_key *key,
+ u32 data_size)
+{
+ struct btrfs_item_batch batch;
+
+ batch.keys = key;
+ batch.data_sizes = &data_size;
+ batch.total_data_size = data_size;
+ batch.nr = 1;
+
+ setup_items_for_insert(root, path, &batch);
+}
+
+/*
+ * 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,
+ const struct btrfs_item_batch *batch)
+{
+ int ret = 0;
+ int slot;
+ u32 total_size;
+
+ total_size = batch->total_data_size + (batch->nr * sizeof(struct btrfs_item));
+ ret = btrfs_search_slot(trans, root, &batch->keys[0], path, total_size, 1);
+ if (ret == 0)
+ return -EEXIST;
+ if (ret < 0)
+ return ret;
+
+ slot = path->slots[0];
+ BUG_ON(slot < 0);
+
+ setup_items_for_insert(root, path, batch);
+ return 0;
+}
+
+/*
+ * 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,
+ const 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;
+}
+
+/*
+ * This function duplicates an 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 a 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,
+ const struct btrfs_key *new_key)
+{
+ struct extent_buffer *leaf;
+ int ret;
+ u32 item_size;
+
+ leaf = path->nodes[0];
+ item_size = btrfs_item_size(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]++;
+ btrfs_setup_item_for_insert(root, path, new_key, item_size);
+ 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;
+}
+
+/*
+ * delete the pointer from a given node.
+ *
+ * the tree should have been previously balanced so the deletion does not
+ * empty a node.
+ */
+static void del_ptr(struct btrfs_root *root, struct btrfs_path *path,
+ int level, int slot)
+{
+ struct extent_buffer *parent = path->nodes[level];
+ u32 nritems;
+ int ret;
+
+ nritems = btrfs_header_nritems(parent);
+ if (slot != nritems - 1) {
+ if (level) {
+ ret = btrfs_tree_mod_log_insert_move(parent, slot,
+ slot + 1, nritems - slot - 1);
+ BUG_ON(ret < 0);
+ }
+ 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));
+ } else if (level) {
+ ret = btrfs_tree_mod_log_insert_key(parent, slot,
+ BTRFS_MOD_LOG_KEY_REMOVE, GFP_NOFS);
+ BUG_ON(ret < 0);
+ }
+
+ 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);
+ fixup_low_keys(path, &disk_key, level + 1);
+ }
+ btrfs_mark_buffer_dirty(parent);
+}
+
+/*
+ * 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 void btrfs_del_leaf(struct btrfs_trans_handle *trans,
+ struct btrfs_root *root,
+ struct btrfs_path *path,
+ struct extent_buffer *leaf)
+{
+ WARN_ON(btrfs_header_generation(leaf) != trans->transid);
+ del_ptr(root, path, 1, path->slots[1]);
+
+ /*
+ * 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);
+
+ atomic_inc(&leaf->refs);
+ btrfs_free_tree_block(trans, btrfs_root_id(root), leaf, 0, 1);
+ free_extent_buffer_stale(leaf);
+}
+/*
+ * 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 btrfs_fs_info *fs_info = root->fs_info;
+ struct extent_buffer *leaf;
+ int ret = 0;
+ int wret;
+ u32 nritems;
+
+ leaf = path->nodes[0];
+ nritems = btrfs_header_nritems(leaf);
+
+ if (slot + nr != nritems) {
+ const u32 last_off = btrfs_item_offset(leaf, slot + nr - 1);
+ const int data_end = leaf_data_end(leaf);
+ struct btrfs_map_token token;
+ u32 dsize = 0;
+ int i;
+
+ for (i = 0; i < nr; i++)
+ dsize += btrfs_item_size(leaf, slot + i);
+
+ memmove_extent_buffer(leaf, BTRFS_LEAF_DATA_OFFSET +
+ data_end + dsize,
+ BTRFS_LEAF_DATA_OFFSET + data_end,
+ last_off - data_end);
+
+ btrfs_init_map_token(&token, leaf);
+ for (i = slot + nr; i < nritems; i++) {
+ u32 ioff;
+
+ ioff = btrfs_token_item_offset(&token, i);
+ btrfs_set_token_item_offset(&token, i, 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_clean_tree_block(leaf);
+ btrfs_del_leaf(trans, root, path, leaf);
+ }
+ } 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);
+ fixup_low_keys(path, &disk_key, 1);
+ }
+
+ /*
+ * Try to delete the leaf if it is mostly empty. We do this by
+ * trying to move all its items into its left and right neighbours.
+ * If we can't move all the items, then we don't delete it - it's
+ * not ideal, but future insertions might fill the leaf with more
+ * items, or items from other leaves might be moved later into our
+ * leaf due to deletions on those leaves.
+ */
+ if (used < BTRFS_LEAF_DATA_SIZE(fs_info) / 3) {
+ u32 min_push_space;
+
+ /* 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];
+ atomic_inc(&leaf->refs);
+ /*
+ * We want to be able to at least push one item to the
+ * left neighbour leaf, and that's the first item.
+ */
+ min_push_space = sizeof(struct btrfs_item) +
+ btrfs_item_size(leaf, 0);
+ wret = push_leaf_left(trans, root, path, 0,
+ min_push_space, 1, (u32)-1);
+ if (wret < 0 && wret != -ENOSPC)
+ ret = wret;
+
+ if (path->nodes[0] == leaf &&
+ btrfs_header_nritems(leaf)) {
+ /*
+ * If we were not able to push all items from our
+ * leaf to its left neighbour, then attempt to
+ * either push all the remaining items to the
+ * right neighbour or none. There's no advantage
+ * in pushing only some items, instead of all, as
+ * it's pointless to end up with a leaf having
+ * too few items while the neighbours can be full
+ * or nearly full.
+ */
+ nritems = btrfs_header_nritems(leaf);
+ min_push_space = leaf_space_used(leaf, 0, nritems);
+ wret = push_leaf_right(trans, root, path, 0,
+ min_push_space, 1, 0);
+ if (wret < 0 && wret != -ENOSPC)
+ ret = wret;
+ }
+
+ if (btrfs_header_nritems(leaf) == 0) {
+ path->slots[1] = slot;
+ btrfs_del_leaf(trans, root, path, leaf);
+ free_extent_buffer(leaf);
+ ret = 0;
+ } 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_key orig_key;
+ struct btrfs_disk_key found_key;
+ int ret;
+
+ btrfs_item_key_to_cpu(path->nodes[0], &key, 0);
+ orig_key = key;
+
+ if (key.offset > 0) {
+ key.offset--;
+ } else if (key.type > 0) {
+ key.type--;
+ key.offset = (u64)-1;
+ } else if (key.objectid > 0) {
+ key.objectid--;
+ key.type = (u8)-1;
+ key.offset = (u64)-1;
+ } else {
+ return 1;
+ }
+
+ btrfs_release_path(path);
+ ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
+ if (ret <= 0)
+ return ret;
+
+ /*
+ * Previous key not found. Even if we were at slot 0 of the leaf we had
+ * before releasing the path and calling btrfs_search_slot(), we now may
+ * be in a slot pointing to the same original key - this can happen if
+ * after we released the path, one of more items were moved from a
+ * sibling leaf into the front of the leaf we had due to an insertion
+ * (see push_leaf_right()).
+ * If we hit this case and our slot is > 0 and just decrement the slot
+ * so that the caller does not process the same key again, which may or
+ * may not break the caller, depending on its logic.
+ */
+ if (path->slots[0] < btrfs_header_nritems(path->nodes[0])) {
+ btrfs_item_key(path->nodes[0], &found_key, path->slots[0]);
+ ret = comp_keys(&found_key, &orig_key);
+ if (ret == 0) {
+ if (path->slots[0] > 0) {
+ path->slots[0]--;
+ return 0;
+ }
+ /*
+ * At slot 0, same key as before, it means orig_key is
+ * the lowest, leftmost, key in the tree. We're done.
+ */
+ return 1;
+ }
+ }
+
+ btrfs_item_key(path->nodes[0], &found_key, 0);
+ ret = comp_keys(&found_key, &key);
+ /*
+ * We might have had an item with the previous key in the tree right
+ * before we released our path. And after we released our path, that
+ * item might have been pushed to the first slot (0) of the leaf we
+ * were holding due to a tree balance. Alternatively, an item with the
+ * previous key can exist as the only element of a leaf (big fat item).
+ * Therefore account for these 2 cases, so that our callers (like
+ * btrfs_previous_item) don't miss an existing item with a key matching
+ * the previous key we computed above.
+ */
+ 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 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 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_path *path,
+ u64 min_trans)
+{
+ struct extent_buffer *cur;
+ struct btrfs_key found_key;
+ int slot;
+ int sret;
+ u32 nritems;
+ int level;
+ int ret = 1;
+ int keep_locks = path->keep_locks;
+
+ ASSERT(!path->nowait);
+ path->keep_locks = 1;
+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 = btrfs_bin_search(cur, min_key, &slot);
+ if (sret < 0) {
+ ret = sret;
+ goto out;
+ }
+
+ /* 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 min_trans parameters.
+ * If it is too old, skip to the next one.
+ */
+ while (slot < nritems) {
+ u64 gen;
+
+ gen = btrfs_node_ptr_generation(cur, slot);
+ if (gen < min_trans) {
+ slot++;
+ continue;
+ }
+ break;
+ }
+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;
+ sret = btrfs_find_next_key(root, path, min_key, level,
+ 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;
+ goto out;
+ }
+ cur = btrfs_read_node_slot(cur, slot);
+ if (IS_ERR(cur)) {
+ ret = PTR_ERR(cur);
+ goto out;
+ }
+
+ btrfs_tree_read_lock(cur);
+
+ path->locks[level - 1] = BTRFS_READ_LOCK;
+ path->nodes[level - 1] = cur;
+ unlock_up(path, level, 1, 0, NULL);
+ }
+out:
+ path->keep_locks = keep_locks;
+ if (ret == 0) {
+ btrfs_unlock_up_safe(path, path->lowest_level + 1);
+ memcpy(min_key, &found_key, sizeof(found_key));
+ }
+ 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 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, u64 min_trans)
+{
+ int slot;
+ struct extent_buffer *c;
+
+ WARN_ON(!path->keep_locks && !path->skip_locking);
+ 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] || path->skip_locking) {
+ 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 gen = btrfs_node_ptr_generation(c, slot);
+
+ if (gen < min_trans) {
+ slot++;
+ goto next;
+ }
+ btrfs_node_key_to_cpu(c, key, slot);
+ }
+ return 0;
+ }
+ return 1;
+}
+
+int btrfs_next_old_leaf(struct btrfs_root *root, struct btrfs_path *path,
+ u64 time_seq)
+{
+ int slot;
+ int level;
+ struct extent_buffer *c;
+ struct extent_buffer *next;
+ struct btrfs_fs_info *fs_info = root->fs_info;
+ struct btrfs_key key;
+ bool need_commit_sem = false;
+ u32 nritems;
+ int ret;
+ int i;
+
+ /*
+ * The nowait semantics are used only for write paths, where we don't
+ * use the tree mod log and sequence numbers.
+ */
+ if (time_seq)
+ ASSERT(!path->nowait);
+
+ 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;
+ btrfs_release_path(path);
+
+ path->keep_locks = 1;
+
+ if (time_seq) {
+ ret = btrfs_search_old_slot(root, &key, path, time_seq);
+ } else {
+ if (path->need_commit_sem) {
+ path->need_commit_sem = 0;
+ need_commit_sem = true;
+ if (path->nowait) {
+ if (!down_read_trylock(&fs_info->commit_root_sem)) {
+ ret = -EAGAIN;
+ goto done;
+ }
+ } else {
+ down_read(&fs_info->commit_root_sem);
+ }
+ }
+ ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
+ }
+ path->keep_locks = 0;
+
+ if (ret < 0)
+ goto done;
+
+ 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;
+ }
+ /*
+ * So the above check misses one case:
+ * - after releasing the path above, someone has removed the item that
+ * used to be at the very end of the block, and balance between leafs
+ * gets another one with bigger key.offset to replace it.
+ *
+ * This one should be returned as well, or we can get leaf corruption
+ * later(esp. in __btrfs_drop_extents()).
+ *
+ * And a bit more explanation about this check,
+ * with ret > 0, the key isn't found, the path points to the slot
+ * where it should be inserted, so the path->slots[0] item must be the
+ * bigger one.
+ */
+ if (nritems > 0 && ret > 0 && path->slots[0] == nritems - 1) {
+ 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;
+ }
+
+
+ /*
+ * Our current level is where we're going to start from, and to
+ * make sure lockdep doesn't complain we need to drop our locks
+ * and nodes from 0 to our current level.
+ */
+ for (i = 0; i < level; i++) {
+ if (path->locks[level]) {
+ btrfs_tree_read_unlock(path->nodes[i]);
+ path->locks[i] = 0;
+ }
+ free_extent_buffer(path->nodes[i]);
+ path->nodes[i] = NULL;
+ }
+
+ next = c;
+ ret = read_block_for_search(root, path, &next, level,
+ slot, &key);
+ if (ret == -EAGAIN && !path->nowait)
+ goto again;
+
+ if (ret < 0) {
+ btrfs_release_path(path);
+ goto done;
+ }
+
+ if (!path->skip_locking) {
+ ret = btrfs_try_tree_read_lock(next);
+ if (!ret && path->nowait) {
+ ret = -EAGAIN;
+ goto done;
+ }
+ if (!ret && time_seq) {
+ /*
+ * If we don't get the lock, we may be racing
+ * with push_leaf_left, holding that lock while
+ * itself waiting for the leaf we've currently
+ * locked. To solve this situation, we give up
+ * on our lock and cycle.
+ */
+ free_extent_buffer(next);
+ btrfs_release_path(path);
+ cond_resched();
+ goto again;
+ }
+ if (!ret)
+ btrfs_tree_read_lock(next);
+ }
+ break;
+ }
+ path->slots[level] = slot;
+ while (1) {
+ level--;
+ path->nodes[level] = next;
+ path->slots[level] = 0;
+ if (!path->skip_locking)
+ path->locks[level] = BTRFS_READ_LOCK;
+ if (!level)
+ break;
+
+ ret = read_block_for_search(root, path, &next, level,
+ 0, &key);
+ if (ret == -EAGAIN && !path->nowait)
+ goto again;
+
+ if (ret < 0) {
+ btrfs_release_path(path);
+ goto done;
+ }
+
+ if (!path->skip_locking) {
+ if (path->nowait) {
+ if (!btrfs_try_tree_read_lock(next)) {
+ ret = -EAGAIN;
+ goto done;
+ }
+ } else {
+ btrfs_tree_read_lock(next);
+ }
+ }
+ }
+ ret = 0;
+done:
+ unlock_up(path, 0, 1, 0, NULL);
+ if (need_commit_sem) {
+ int ret2;
+
+ path->need_commit_sem = 1;
+ ret2 = finish_need_commit_sem_search(path);
+ up_read(&fs_info->commit_root_sem);
+ if (ret2)
+ ret = ret2;
+ }
+
+ 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) {
+ 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;
+}
+
+/*
+ * search in extent tree to find a previous Metadata/Data extent item with
+ * min objecitd.
+ *
+ * returns 0 if something is found, 1 if nothing was found and < 0 on error
+ */
+int btrfs_previous_extent_item(struct btrfs_root *root,
+ struct btrfs_path *path, u64 min_objectid)
+{
+ struct btrfs_key found_key;
+ struct extent_buffer *leaf;
+ u32 nritems;
+ int ret;
+
+ while (1) {
+ if (path->slots[0] == 0) {
+ 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 == BTRFS_EXTENT_ITEM_KEY ||
+ found_key.type == BTRFS_METADATA_ITEM_KEY)
+ return 0;
+ if (found_key.objectid == min_objectid &&
+ found_key.type < BTRFS_EXTENT_ITEM_KEY)
+ break;
+ }
+ return 1;
+}