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8d7be552a7
linux/fs/btrfs/ctree.c
Chris Mason 8d7be552a7 Btrfs: fix check_node and check_leaf to use less cpu 
Signed-off-by: Chris Mason <chris.mason@oracle.com>
2007-05-10 11:24:42 -04:00

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#include <linux/module.h>
#include "ctree.h"
#include "disk-io.h"
#include "transaction.h"
static int split_node(struct btrfs_trans_handle *trans, struct btrfs_root
*root, struct btrfs_path *path, int level);
static int split_leaf(struct btrfs_trans_handle *trans, struct btrfs_root
*root, struct btrfs_key *ins_key,
struct btrfs_path *path, int data_size);
static int push_node_left(struct btrfs_trans_handle *trans, struct btrfs_root
*root, struct buffer_head *dst, struct buffer_head
*src);
static int balance_node_right(struct btrfs_trans_handle *trans, struct
btrfs_root *root, struct buffer_head *dst_buf,
struct buffer_head *src_buf);
static int del_ptr(struct btrfs_trans_handle *trans, struct btrfs_root *root,
struct btrfs_path *path, int level, int slot);
inline void btrfs_init_path(struct btrfs_path *p)
{
memset(p, 0, sizeof(*p));
}
struct btrfs_path *btrfs_alloc_path(void)
{
struct btrfs_path *path;
path = kmem_cache_alloc(btrfs_path_cachep, GFP_NOFS);
if (path)
btrfs_init_path(path);
return path;
}
void btrfs_free_path(struct btrfs_path *p)
{
btrfs_release_path(NULL, p);
kmem_cache_free(btrfs_path_cachep, p);
}
void btrfs_release_path(struct btrfs_root *root, struct btrfs_path *p)
{
int i;
for (i = 0; i < BTRFS_MAX_LEVEL; i++) {
if (!p->nodes[i])
break;
btrfs_block_release(root, p->nodes[i]);
}
memset(p, 0, sizeof(*p));
}
static int btrfs_cow_block(struct btrfs_trans_handle *trans, struct btrfs_root
*root, struct buffer_head *buf, struct buffer_head
*parent, int parent_slot, struct buffer_head
**cow_ret)
{
struct buffer_head *cow;
struct btrfs_node *cow_node;
if (btrfs_header_generation(btrfs_buffer_header(buf)) ==
trans->transid) {
*cow_ret = buf;
return 0;
}
cow = btrfs_alloc_free_block(trans, root, buf->b_blocknr);
cow_node = btrfs_buffer_node(cow);
if (buf->b_size != root->blocksize || cow->b_size != root->blocksize)
WARN_ON(1);
memcpy(cow_node, btrfs_buffer_node(buf), root->blocksize);
btrfs_set_header_blocknr(&cow_node->header, bh_blocknr(cow));
btrfs_set_header_generation(&cow_node->header, trans->transid);
btrfs_set_header_owner(&cow_node->header, root->root_key.objectid);
btrfs_inc_ref(trans, root, buf);
if (buf == root->node) {
root->node = cow;
get_bh(cow);
if (buf != root->commit_root) {
btrfs_free_extent(trans, root, bh_blocknr(buf), 1, 1);
}
btrfs_block_release(root, buf);
} else {
btrfs_set_node_blockptr(btrfs_buffer_node(parent), parent_slot,
bh_blocknr(cow));
btrfs_mark_buffer_dirty(parent);
btrfs_free_extent(trans, root, bh_blocknr(buf), 1, 1);
}
btrfs_block_release(root, buf);
mark_buffer_dirty(cow);
*cow_ret = cow;
return 0;
}
/*
* The leaf data grows from end-to-front in the node.
* this returns the address of the start of the last item,
* which is the stop of the leaf data stack
*/
static inline unsigned int leaf_data_end(struct btrfs_root *root,
struct btrfs_leaf *leaf)
{
u32 nr = btrfs_header_nritems(&leaf->header);
if (nr == 0)
return BTRFS_LEAF_DATA_SIZE(root);
return btrfs_item_offset(leaf->items + nr - 1);
}
/*
* compare two keys in a memcmp fashion
*/
static int comp_keys(struct btrfs_disk_key *disk, struct btrfs_key *k2)
{
struct btrfs_key k1;
btrfs_disk_key_to_cpu(&k1, disk);
if (k1.objectid > k2->objectid)
return 1;
if (k1.objectid < k2->objectid)
return -1;
if (k1.flags > k2->flags)
return 1;
if (k1.flags < k2->flags)
return -1;
if (k1.offset > k2->offset)
return 1;
if (k1.offset < k2->offset)
return -1;
return 0;
}
static int check_node(struct btrfs_root *root, struct btrfs_path *path,
int level)
{
struct btrfs_node *parent = NULL;
struct btrfs_node *node = btrfs_buffer_node(path->nodes[level]);
int parent_slot;
int slot;
struct btrfs_key cpukey;
u32 nritems = btrfs_header_nritems(&node->header);
if (path->nodes[level + 1])
parent = btrfs_buffer_node(path->nodes[level + 1]);
parent_slot = path->slots[level + 1];
slot = path->slots[level];
BUG_ON(nritems == 0);
if (parent) {
struct btrfs_disk_key *parent_key;
parent_key = &parent->ptrs[parent_slot].key;
BUG_ON(memcmp(parent_key, &node->ptrs[0].key,
sizeof(struct btrfs_disk_key)));
BUG_ON(btrfs_node_blockptr(parent, parent_slot) !=
btrfs_header_blocknr(&node->header));
}
BUG_ON(nritems > BTRFS_NODEPTRS_PER_BLOCK(root));
if (slot != 0) {
btrfs_disk_key_to_cpu(&cpukey, &node->ptrs[slot - 1].key);
BUG_ON(comp_keys(&node->ptrs[slot].key, &cpukey) <= 0);
}
if (slot < nritems - 1) {
btrfs_disk_key_to_cpu(&cpukey, &node->ptrs[slot + 1].key);
BUG_ON(comp_keys(&node->ptrs[slot].key, &cpukey) >= 0);
}
return 0;
}
static int check_leaf(struct btrfs_root *root, struct btrfs_path *path,
int level)
{
struct btrfs_leaf *leaf = btrfs_buffer_leaf(path->nodes[level]);
struct btrfs_node *parent = NULL;
int parent_slot;
int slot = path->slots[0];
struct btrfs_key cpukey;
u32 nritems = btrfs_header_nritems(&leaf->header);
if (path->nodes[level + 1])
parent = btrfs_buffer_node(path->nodes[level + 1]);
parent_slot = path->slots[level + 1];
BUG_ON(btrfs_leaf_free_space(root, leaf) < 0);
if (nritems == 0)
return 0;
if (parent) {
struct btrfs_disk_key *parent_key;
parent_key = &parent->ptrs[parent_slot].key;
BUG_ON(memcmp(parent_key, &leaf->items[0].key,
sizeof(struct btrfs_disk_key)));
BUG_ON(btrfs_node_blockptr(parent, parent_slot) !=
btrfs_header_blocknr(&leaf->header));
}
if (slot != 0) {
btrfs_disk_key_to_cpu(&cpukey, &leaf->items[slot - 1].key);
BUG_ON(comp_keys(&leaf->items[slot].key, &cpukey) <= 0);
BUG_ON(btrfs_item_offset(leaf->items + slot - 1) !=
btrfs_item_end(leaf->items + slot));
}
if (slot < nritems - 1) {
btrfs_disk_key_to_cpu(&cpukey, &leaf->items[slot + 1].key);
BUG_ON(comp_keys(&leaf->items[slot].key, &cpukey) >= 0);
BUG_ON(btrfs_item_offset(leaf->items + slot) !=
btrfs_item_end(leaf->items + slot + 1));
}
BUG_ON(btrfs_item_offset(leaf->items) +
btrfs_item_size(leaf->items) != BTRFS_LEAF_DATA_SIZE(root));
return 0;
}
static int check_block(struct btrfs_root *root, struct btrfs_path *path,
int level)
{
struct btrfs_node *node = btrfs_buffer_node(path->nodes[level]);
if (memcmp(node->header.fsid, root->fs_info->disk_super->fsid,
sizeof(node->header.fsid)))
BUG();
if (level == 0)
return check_leaf(root, path, level);
return check_node(root, path, level);
}
/*
* search for key in the array p. items p are item_size apart
* and there are 'max' items in p
* the slot in the array is returned via slot, and it points to
* the place where you would insert key if it is not found in
* the array.
*
* slot may point to max if the key is bigger than all of the keys
*/
static int generic_bin_search(char *p, int item_size, struct btrfs_key *key,
int max, int *slot)
{
int low = 0;
int high = max;
int mid;
int ret;
struct btrfs_disk_key *tmp;
while(low < high) {
mid = (low + high) / 2;
tmp = (struct btrfs_disk_key *)(p + mid * item_size);
ret = comp_keys(tmp, key);
if (ret < 0)
low = mid + 1;
else if (ret > 0)
high = mid;
else {
*slot = mid;
return 0;
}
}
*slot = low;
return 1;
}
/*
* simple bin_search frontend that does the right thing for
* leaves vs nodes
*/
static int bin_search(struct btrfs_node *c, struct btrfs_key *key, int *slot)
{
if (btrfs_is_leaf(c)) {
struct btrfs_leaf *l = (struct btrfs_leaf *)c;
return generic_bin_search((void *)l->items,
sizeof(struct btrfs_item),
key, btrfs_header_nritems(&c->header),
slot);
} else {
return generic_bin_search((void *)c->ptrs,
sizeof(struct btrfs_key_ptr),
key, btrfs_header_nritems(&c->header),
slot);
}
return -1;
}
static struct buffer_head *read_node_slot(struct btrfs_root *root,
struct buffer_head *parent_buf,
int slot)
{
struct btrfs_node *node = btrfs_buffer_node(parent_buf);
if (slot < 0)
return NULL;
if (slot >= btrfs_header_nritems(&node->header))
return NULL;
return read_tree_block(root, btrfs_node_blockptr(node, slot));
}
static int balance_level(struct btrfs_trans_handle *trans, struct btrfs_root
*root, struct btrfs_path *path, int level)
{
struct buffer_head *right_buf;
struct buffer_head *mid_buf;
struct buffer_head *left_buf;
struct buffer_head *parent_buf = NULL;
struct btrfs_node *right = NULL;
struct btrfs_node *mid;
struct btrfs_node *left = NULL;
struct btrfs_node *parent = NULL;
int ret = 0;
int wret;
int pslot;
int orig_slot = path->slots[level];
u64 orig_ptr;
if (level == 0)
return 0;
mid_buf = path->nodes[level];
mid = btrfs_buffer_node(mid_buf);
orig_ptr = btrfs_node_blockptr(mid, orig_slot);
if (level < BTRFS_MAX_LEVEL - 1)
parent_buf = 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_buf) {
struct buffer_head *child;
u64 blocknr = bh_blocknr(mid_buf);
if (btrfs_header_nritems(&mid->header) != 1)
return 0;
/* promote the child to a root */
child = read_node_slot(root, mid_buf, 0);
BUG_ON(!child);
root->node = child;
path->nodes[level] = NULL;
clean_tree_block(trans, root, mid_buf);
wait_on_buffer(mid_buf);
/* once for the path */
btrfs_block_release(root, mid_buf);
/* once for the root ptr */
btrfs_block_release(root, mid_buf);
return btrfs_free_extent(trans, root, blocknr, 1, 1);
}
parent = btrfs_buffer_node(parent_buf);
if (btrfs_header_nritems(&mid->header) >
BTRFS_NODEPTRS_PER_BLOCK(root) / 4)
return 0;
left_buf = read_node_slot(root, parent_buf, pslot - 1);
right_buf = read_node_slot(root, parent_buf, pslot + 1);
/* first, try to make some room in the middle buffer */
if (left_buf) {
btrfs_cow_block(trans, root, left_buf, parent_buf, pslot - 1,
&left_buf);
left = btrfs_buffer_node(left_buf);
orig_slot += btrfs_header_nritems(&left->header);
wret = push_node_left(trans, root, left_buf, mid_buf);
if (wret < 0)
ret = wret;
}
/*
* then try to empty the right most buffer into the middle
*/
if (right_buf) {
btrfs_cow_block(trans, root, right_buf, parent_buf, pslot + 1,
&right_buf);
right = btrfs_buffer_node(right_buf);
wret = push_node_left(trans, root, mid_buf, right_buf);
if (wret < 0)
ret = wret;
if (btrfs_header_nritems(&right->header) == 0) {
u64 blocknr = bh_blocknr(right_buf);
clean_tree_block(trans, root, right_buf);
wait_on_buffer(right_buf);
btrfs_block_release(root, right_buf);
right_buf = NULL;
right = NULL;
wret = del_ptr(trans, root, path, level + 1, pslot +
1);
if (wret)
ret = wret;
wret = btrfs_free_extent(trans, root, blocknr, 1, 1);
if (wret)
ret = wret;
} else {
btrfs_memcpy(root, parent,
&parent->ptrs[pslot + 1].key,
&right->ptrs[0].key,
sizeof(struct btrfs_disk_key));
btrfs_mark_buffer_dirty(parent_buf);
}
}
if (btrfs_header_nritems(&mid->header) == 1) {
/*
* we're not allowed to leave a node with one item in the
* tree during a delete. A deletion from lower in the tree
* could try to delete the only pointer in this node.
* So, pull some keys from the left.
* There has to be a left pointer at this point because
* otherwise we would have pulled some pointers from the
* right
*/
BUG_ON(!left_buf);
wret = balance_node_right(trans, root, mid_buf, left_buf);
if (wret < 0)
ret = wret;
BUG_ON(wret == 1);
}
if (btrfs_header_nritems(&mid->header) == 0) {
/* we've managed to empty the middle node, drop it */
u64 blocknr = bh_blocknr(mid_buf);
clean_tree_block(trans, root, mid_buf);
wait_on_buffer(mid_buf);
btrfs_block_release(root, mid_buf);
mid_buf = NULL;
mid = NULL;
wret = del_ptr(trans, root, path, level + 1, pslot);
if (wret)
ret = wret;
wret = btrfs_free_extent(trans, root, blocknr, 1, 1);
if (wret)
ret = wret;
} else {
/* update the parent key to reflect our changes */
btrfs_memcpy(root, parent,
&parent->ptrs[pslot].key, &mid->ptrs[0].key,
sizeof(struct btrfs_disk_key));
btrfs_mark_buffer_dirty(parent_buf);
}
/* update the path */
if (left_buf) {
if (btrfs_header_nritems(&left->header) > orig_slot) {
get_bh(left_buf);
path->nodes[level] = left_buf;
path->slots[level + 1] -= 1;
path->slots[level] = orig_slot;
if (mid_buf)
btrfs_block_release(root, mid_buf);
} else {
orig_slot -= btrfs_header_nritems(&left->header);
path->slots[level] = orig_slot;
}
}
/* double check we haven't messed things up */
check_block(root, path, level);
if (orig_ptr !=
btrfs_node_blockptr(btrfs_buffer_node(path->nodes[level]),
path->slots[level]))
BUG();
if (right_buf)
btrfs_block_release(root, right_buf);
if (left_buf)
btrfs_block_release(root, left_buf);
return ret;
}
/* returns zero if the push worked, non-zero otherwise */
static int push_nodes_for_insert(struct btrfs_trans_handle *trans,
struct btrfs_root *root,
struct btrfs_path *path, int level)
{
struct buffer_head *right_buf;
struct buffer_head *mid_buf;
struct buffer_head *left_buf;
struct buffer_head *parent_buf = NULL;
struct btrfs_node *right = NULL;
struct btrfs_node *mid;
struct btrfs_node *left = NULL;
struct btrfs_node *parent = NULL;
int ret = 0;
int wret;
int pslot;
int orig_slot = path->slots[level];
u64 orig_ptr;
if (level == 0)
return 1;
mid_buf = path->nodes[level];
mid = btrfs_buffer_node(mid_buf);
orig_ptr = btrfs_node_blockptr(mid, orig_slot);
if (level < BTRFS_MAX_LEVEL - 1)
parent_buf = path->nodes[level + 1];
pslot = path->slots[level + 1];
if (!parent_buf)
return 1;
parent = btrfs_buffer_node(parent_buf);
left_buf = read_node_slot(root, parent_buf, pslot - 1);
/* first, try to make some room in the middle buffer */
if (left_buf) {
u32 left_nr;
left = btrfs_buffer_node(left_buf);
left_nr = btrfs_header_nritems(&left->header);
if (left_nr >= BTRFS_NODEPTRS_PER_BLOCK(root) - 1) {
wret = 1;
} else {
btrfs_cow_block(trans, root, left_buf, parent_buf,
pslot - 1, &left_buf);
left = btrfs_buffer_node(left_buf);
wret = push_node_left(trans, root, left_buf, mid_buf);
}
if (wret < 0)
ret = wret;
if (wret == 0) {
orig_slot += left_nr;
btrfs_memcpy(root, parent,
&parent->ptrs[pslot].key,
&mid->ptrs[0].key,
sizeof(struct btrfs_disk_key));
btrfs_mark_buffer_dirty(parent_buf);
if (btrfs_header_nritems(&left->header) > orig_slot) {
path->nodes[level] = left_buf;
path->slots[level + 1] -= 1;
path->slots[level] = orig_slot;
btrfs_block_release(root, mid_buf);
} else {
orig_slot -=
btrfs_header_nritems(&left->header);
path->slots[level] = orig_slot;
btrfs_block_release(root, left_buf);
}
check_node(root, path, level);
return 0;
}
btrfs_block_release(root, left_buf);
}
right_buf = read_node_slot(root, parent_buf, pslot + 1);
/*
* then try to empty the right most buffer into the middle
*/
if (right_buf) {
u32 right_nr;
right = btrfs_buffer_node(right_buf);
right_nr = btrfs_header_nritems(&right->header);
if (right_nr >= BTRFS_NODEPTRS_PER_BLOCK(root) - 1) {
wret = 1;
} else {
btrfs_cow_block(trans, root, right_buf,
parent_buf, pslot + 1, &right_buf);
right = btrfs_buffer_node(right_buf);
wret = balance_node_right(trans, root,
right_buf, mid_buf);
}
if (wret < 0)
ret = wret;
if (wret == 0) {
btrfs_memcpy(root, parent,
&parent->ptrs[pslot + 1].key,
&right->ptrs[0].key,
sizeof(struct btrfs_disk_key));
btrfs_mark_buffer_dirty(parent_buf);
if (btrfs_header_nritems(&mid->header) <= orig_slot) {
path->nodes[level] = right_buf;
path->slots[level + 1] += 1;
path->slots[level] = orig_slot -
btrfs_header_nritems(&mid->header);
btrfs_block_release(root, mid_buf);
} else {
btrfs_block_release(root, right_buf);
}
check_node(root, path, level);
return 0;
}
btrfs_block_release(root, right_buf);
}
check_node(root, path, level);
return 1;
}
/*
* look for key in the tree. path is filled in with nodes along the way
* if key is found, we return zero and you can find the item in the leaf
* level of the path (level 0)
*
* If the key isn't found, the path points to the slot where it should
* be inserted, and 1 is returned. If there are other errors during the
* search a negative error number is returned.
*
* if ins_len > 0, nodes and leaves will be split as we walk down the
* tree. if ins_len < 0, nodes will be merged as we walk down the tree (if
* possible)
*/
int btrfs_search_slot(struct btrfs_trans_handle *trans, struct btrfs_root
*root, struct btrfs_key *key, struct btrfs_path *p, int
ins_len, int cow)
{
struct buffer_head *b;
struct buffer_head *cow_buf;
struct btrfs_node *c;
int slot;
int ret;
int level;
WARN_ON(p->nodes[0] != NULL);
WARN_ON(!mutex_is_locked(&root->fs_info->fs_mutex));
again:
b = root->node;
get_bh(b);
while (b) {
c = btrfs_buffer_node(b);
level = btrfs_header_level(&c->header);
if (cow) {
int wret;
wret = btrfs_cow_block(trans, root, b,
p->nodes[level + 1],
p->slots[level + 1],
&cow_buf);
b = cow_buf;
c = btrfs_buffer_node(b);
}
BUG_ON(!cow && ins_len);
if (level != btrfs_header_level(&c->header))
WARN_ON(1);
level = btrfs_header_level(&c->header);
p->nodes[level] = b;
ret = check_block(root, p, level);
if (ret)
return -1;
ret = bin_search(c, key, &slot);
if (!btrfs_is_leaf(c)) {
if (ret && slot > 0)
slot -= 1;
p->slots[level] = slot;
if (ins_len > 0 && btrfs_header_nritems(&c->header) >=
BTRFS_NODEPTRS_PER_BLOCK(root) - 1) {
int sret = split_node(trans, root, p, level);
BUG_ON(sret > 0);
if (sret)
return sret;
b = p->nodes[level];
c = btrfs_buffer_node(b);
slot = p->slots[level];
} else if (ins_len < 0) {
int sret = balance_level(trans, root, p,
level);
if (sret)
return sret;
b = p->nodes[level];
if (!b)
goto again;
c = btrfs_buffer_node(b);
slot = p->slots[level];
BUG_ON(btrfs_header_nritems(&c->header) == 1);
}
b = read_tree_block(root, btrfs_node_blockptr(c, slot));
} else {
struct btrfs_leaf *l = (struct btrfs_leaf *)c;
p->slots[level] = slot;
if (ins_len > 0 && btrfs_leaf_free_space(root, l) <
sizeof(struct btrfs_item) + ins_len) {
int sret = split_leaf(trans, root, key,
p, ins_len);
BUG_ON(sret > 0);
if (sret)
return sret;
}
return ret;
}
}
return 1;
}
/*
* adjust the pointers going up the tree, starting at level
* making sure the right key of each node is points to 'key'.
* This is used after shifting pointers to the left, so it stops
* fixing up pointers when a given leaf/node is not in slot 0 of the
* higher levels
*
* If this fails to write a tree block, it returns -1, but continues
* fixing up the blocks in ram so the tree is consistent.
*/
static int fixup_low_keys(struct btrfs_trans_handle *trans, struct btrfs_root
*root, struct btrfs_path *path, struct btrfs_disk_key
*key, int level)
{
int i;
int ret = 0;
for (i = level; i < BTRFS_MAX_LEVEL; i++) {
struct btrfs_node *t;
int tslot = path->slots[i];
if (!path->nodes[i])
break;
t = btrfs_buffer_node(path->nodes[i]);
btrfs_memcpy(root, t, &t->ptrs[tslot].key, key, sizeof(*key));
btrfs_mark_buffer_dirty(path->nodes[i]);
if (tslot != 0)
break;
}
return ret;
}
/*
* try to push data from one node into the next node left in the
* tree.
*
* returns 0 if some ptrs were pushed left, < 0 if there was some horrible
* error, and > 0 if there was no room in the left hand block.
*/
static int push_node_left(struct btrfs_trans_handle *trans, struct btrfs_root
*root, struct buffer_head *dst_buf, struct
buffer_head *src_buf)
{
struct btrfs_node *src = btrfs_buffer_node(src_buf);
struct btrfs_node *dst = btrfs_buffer_node(dst_buf);
int push_items = 0;
int src_nritems;
int dst_nritems;
int ret = 0;
src_nritems = btrfs_header_nritems(&src->header);
dst_nritems = btrfs_header_nritems(&dst->header);
push_items = BTRFS_NODEPTRS_PER_BLOCK(root) - dst_nritems;
if (push_items <= 0) {
return 1;
}
if (src_nritems < push_items)
push_items = src_nritems;
btrfs_memcpy(root, dst, dst->ptrs + dst_nritems, src->ptrs,
push_items * sizeof(struct btrfs_key_ptr));
if (push_items < src_nritems) {
btrfs_memmove(root, src, src->ptrs, src->ptrs + push_items,
(src_nritems - push_items) *
sizeof(struct btrfs_key_ptr));
}
btrfs_set_header_nritems(&src->header, src_nritems - push_items);
btrfs_set_header_nritems(&dst->header, dst_nritems + push_items);
btrfs_mark_buffer_dirty(src_buf);
btrfs_mark_buffer_dirty(dst_buf);
return ret;
}
/*
* try to push data from one node into the next node right in the
* tree.
*
* returns 0 if some ptrs were pushed, < 0 if there was some horrible
* error, and > 0 if there was no room in the right hand block.
*
* this will only push up to 1/2 the contents of the left node over
*/
static int balance_node_right(struct btrfs_trans_handle *trans, struct
btrfs_root *root, struct buffer_head *dst_buf,
struct buffer_head *src_buf)
{
struct btrfs_node *src = btrfs_buffer_node(src_buf);
struct btrfs_node *dst = btrfs_buffer_node(dst_buf);
int push_items = 0;
int max_push;
int src_nritems;
int dst_nritems;
int ret = 0;
src_nritems = btrfs_header_nritems(&src->header);
dst_nritems = btrfs_header_nritems(&dst->header);
push_items = BTRFS_NODEPTRS_PER_BLOCK(root) - dst_nritems;
if (push_items <= 0) {
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;
btrfs_memmove(root, dst, dst->ptrs + push_items, dst->ptrs,
dst_nritems * sizeof(struct btrfs_key_ptr));
btrfs_memcpy(root, dst, dst->ptrs,
src->ptrs + src_nritems - push_items,
push_items * sizeof(struct btrfs_key_ptr));
btrfs_set_header_nritems(&src->header, src_nritems - push_items);
btrfs_set_header_nritems(&dst->header, dst_nritems + push_items);
btrfs_mark_buffer_dirty(src_buf);
btrfs_mark_buffer_dirty(dst_buf);
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 int insert_new_root(struct btrfs_trans_handle *trans, struct btrfs_root
*root, struct btrfs_path *path, int level)
{
struct buffer_head *t;
struct btrfs_node *lower;
struct btrfs_node *c;
struct btrfs_disk_key *lower_key;
BUG_ON(path->nodes[level]);
BUG_ON(path->nodes[level-1] != root->node);
t = btrfs_alloc_free_block(trans, root, root->node->b_blocknr);
c = btrfs_buffer_node(t);
memset(c, 0, root->blocksize);
btrfs_set_header_nritems(&c->header, 1);
btrfs_set_header_level(&c->header, level);
btrfs_set_header_blocknr(&c->header, bh_blocknr(t));
btrfs_set_header_generation(&c->header, trans->transid);
btrfs_set_header_owner(&c->header, root->root_key.objectid);
lower = btrfs_buffer_node(path->nodes[level-1]);
memcpy(c->header.fsid, root->fs_info->disk_super->fsid,
sizeof(c->header.fsid));
if (btrfs_is_leaf(lower))
lower_key = &((struct btrfs_leaf *)lower)->items[0].key;
else
lower_key = &lower->ptrs[0].key;
btrfs_memcpy(root, c, &c->ptrs[0].key, lower_key,
sizeof(struct btrfs_disk_key));
btrfs_set_node_blockptr(c, 0, bh_blocknr(path->nodes[level - 1]));
btrfs_mark_buffer_dirty(t);
/* the super has an extra ref to root->node */
btrfs_block_release(root, root->node);
root->node = t;
get_bh(t);
path->nodes[level] = t;
path->slots[level] = 0;
return 0;
}
/*
* worker function to insert a single pointer in a node.
* the node should have enough room for the pointer already
*
* slot and level indicate where you want the key to go, and
* blocknr is the block the key points to.
*
* returns zero on success and < 0 on any error
*/
static int insert_ptr(struct btrfs_trans_handle *trans, struct btrfs_root
*root, struct btrfs_path *path, struct btrfs_disk_key
*key, u64 blocknr, int slot, int level)
{
struct btrfs_node *lower;
int nritems;
BUG_ON(!path->nodes[level]);
lower = btrfs_buffer_node(path->nodes[level]);
nritems = btrfs_header_nritems(&lower->header);
if (slot > nritems)
BUG();
if (nritems == BTRFS_NODEPTRS_PER_BLOCK(root))
BUG();
if (slot != nritems) {
btrfs_memmove(root, lower, lower->ptrs + slot + 1,
lower->ptrs + slot,
(nritems - slot) * sizeof(struct btrfs_key_ptr));
}
btrfs_memcpy(root, lower, &lower->ptrs[slot].key,
key, sizeof(struct btrfs_disk_key));
btrfs_set_node_blockptr(lower, slot, blocknr);
btrfs_set_header_nritems(&lower->header, nritems + 1);
btrfs_mark_buffer_dirty(path->nodes[level]);
return 0;
}
/*
* split the node at the specified level in path in two.
* The path is corrected to point to the appropriate node after the split
*
* Before splitting this tries to make some room in the node by pushing
* left and right, if either one works, it returns right away.
*
* returns 0 on success and < 0 on failure
*/
static int split_node(struct btrfs_trans_handle *trans, struct btrfs_root
*root, struct btrfs_path *path, int level)
{
struct buffer_head *t;
struct btrfs_node *c;
struct buffer_head *split_buffer;
struct btrfs_node *split;
int mid;
int ret;
int wret;
u32 c_nritems;
t = path->nodes[level];
c = btrfs_buffer_node(t);
if (t == root->node) {
/* trying to split the root, lets make a new one */
ret = insert_new_root(trans, root, path, level + 1);
if (ret)
return ret;
} else {
ret = push_nodes_for_insert(trans, root, path, level);
t = path->nodes[level];
c = btrfs_buffer_node(t);
if (!ret &&
btrfs_header_nritems(&c->header) <
BTRFS_NODEPTRS_PER_BLOCK(root) - 1)
return 0;
}
c_nritems = btrfs_header_nritems(&c->header);
split_buffer = btrfs_alloc_free_block(trans, root, t->b_blocknr);
split = btrfs_buffer_node(split_buffer);
btrfs_set_header_flags(&split->header, btrfs_header_flags(&c->header));
btrfs_set_header_level(&split->header, btrfs_header_level(&c->header));
btrfs_set_header_blocknr(&split->header, bh_blocknr(split_buffer));
btrfs_set_header_generation(&split->header, trans->transid);
btrfs_set_header_owner(&split->header, root->root_key.objectid);
memcpy(split->header.fsid, root->fs_info->disk_super->fsid,
sizeof(split->header.fsid));
mid = (c_nritems + 1) / 2;
btrfs_memcpy(root, split, split->ptrs, c->ptrs + mid,
(c_nritems - mid) * sizeof(struct btrfs_key_ptr));
btrfs_set_header_nritems(&split->header, c_nritems - mid);
btrfs_set_header_nritems(&c->header, mid);
ret = 0;
btrfs_mark_buffer_dirty(t);
btrfs_mark_buffer_dirty(split_buffer);
wret = insert_ptr(trans, root, path, &split->ptrs[0].key,
bh_blocknr(split_buffer), path->slots[level + 1] + 1,
level + 1);
if (wret)
ret = wret;
if (path->slots[level] >= mid) {
path->slots[level] -= mid;
btrfs_block_release(root, t);
path->nodes[level] = split_buffer;
path->slots[level + 1] += 1;
} else {
btrfs_block_release(root, split_buffer);
}
return ret;
}
/*
* how many bytes are required to store the items in a leaf. start
* and nr indicate which items in the leaf to check. This totals up the
* space used both by the item structs and the item data
*/
static int leaf_space_used(struct btrfs_leaf *l, int start, int nr)
{
int data_len;
int nritems = btrfs_header_nritems(&l->header);
int end = min(nritems, start + nr) - 1;
if (!nr)
return 0;
data_len = btrfs_item_end(l->items + start);
data_len = data_len - btrfs_item_offset(l->items + 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
*/
int btrfs_leaf_free_space(struct btrfs_root *root, struct btrfs_leaf *leaf)
{
int nritems = btrfs_header_nritems(&leaf->header);
return BTRFS_LEAF_DATA_SIZE(root) - leaf_space_used(leaf, 0, nritems);
}
/*
* push some data in the path leaf to the right, trying to free up at
* least data_size bytes. returns zero if the push worked, nonzero otherwise
*
* returns 1 if the push failed because the other node didn't have enough
* room, 0 if everything worked out and < 0 if there were major errors.
*/
static int push_leaf_right(struct btrfs_trans_handle *trans, struct btrfs_root
*root, struct btrfs_path *path, int data_size)
{
struct buffer_head *left_buf = path->nodes[0];
struct btrfs_leaf *left = btrfs_buffer_leaf(left_buf);
struct btrfs_leaf *right;
struct buffer_head *right_buf;
struct buffer_head *upper;
struct btrfs_node *upper_node;
int slot;
int i;
int free_space;
int push_space = 0;
int push_items = 0;
struct btrfs_item *item;
u32 left_nritems;
u32 right_nritems;
slot = path->slots[1];
if (!path->nodes[1]) {
return 1;
}
upper = path->nodes[1];
upper_node = btrfs_buffer_node(upper);
if (slot >= btrfs_header_nritems(&upper_node->header) - 1) {
return 1;
}
right_buf = read_tree_block(root,
btrfs_node_blockptr(btrfs_buffer_node(upper), slot + 1));
right = btrfs_buffer_leaf(right_buf);
free_space = btrfs_leaf_free_space(root, right);
if (free_space < data_size + sizeof(struct btrfs_item)) {
btrfs_block_release(root, right_buf);
return 1;
}
/* cow and double check */
btrfs_cow_block(trans, root, right_buf, upper, slot + 1, &right_buf);
right = btrfs_buffer_leaf(right_buf);
free_space = btrfs_leaf_free_space(root, right);
if (free_space < data_size + sizeof(struct btrfs_item)) {
btrfs_block_release(root, right_buf);
return 1;
}
left_nritems = btrfs_header_nritems(&left->header);
if (left_nritems == 0) {
btrfs_block_release(root, right_buf);
return 1;
}
for (i = left_nritems - 1; i >= 1; i--) {
item = left->items + i;
if (path->slots[0] == i)
push_space += data_size + sizeof(*item);
if (btrfs_item_size(item) + sizeof(*item) + push_space >
free_space)
break;
push_items++;
push_space += btrfs_item_size(item) + sizeof(*item);
}
if (push_items == 0) {
btrfs_block_release(root, right_buf);
return 1;
}
if (push_items == left_nritems)
WARN_ON(1);
right_nritems = btrfs_header_nritems(&right->header);
/* push left to right */
push_space = btrfs_item_end(left->items + left_nritems - push_items);
push_space -= leaf_data_end(root, left);
/* make room in the right data area */
btrfs_memmove(root, right, btrfs_leaf_data(right) +
leaf_data_end(root, right) - push_space,
btrfs_leaf_data(right) +
leaf_data_end(root, right), BTRFS_LEAF_DATA_SIZE(root) -
leaf_data_end(root, right));
/* copy from the left data area */
btrfs_memcpy(root, right, btrfs_leaf_data(right) +
BTRFS_LEAF_DATA_SIZE(root) - push_space,
btrfs_leaf_data(left) + leaf_data_end(root, left),
push_space);
btrfs_memmove(root, right, right->items + push_items, right->items,
right_nritems * sizeof(struct btrfs_item));
/* copy the items from left to right */
btrfs_memcpy(root, right, right->items, left->items +
left_nritems - push_items,
push_items * sizeof(struct btrfs_item));
/* update the item pointers */
right_nritems += push_items;
btrfs_set_header_nritems(&right->header, right_nritems);
push_space = BTRFS_LEAF_DATA_SIZE(root);
for (i = 0; i < right_nritems; i++) {
btrfs_set_item_offset(right->items + i, push_space -
btrfs_item_size(right->items + i));
push_space = btrfs_item_offset(right->items + i);
}
left_nritems -= push_items;
btrfs_set_header_nritems(&left->header, left_nritems);
btrfs_mark_buffer_dirty(left_buf);
btrfs_mark_buffer_dirty(right_buf);
btrfs_memcpy(root, upper_node, &upper_node->ptrs[slot + 1].key,
&right->items[0].key, sizeof(struct btrfs_disk_key));
btrfs_mark_buffer_dirty(upper);
/* then fixup the leaf pointer in the path */
if (path->slots[0] >= left_nritems) {
path->slots[0] -= left_nritems;
btrfs_block_release(root, path->nodes[0]);
path->nodes[0] = right_buf;
path->slots[1] += 1;
} else {
btrfs_block_release(root, right_buf);
}
return 0;
}
/*
* push some data in the path leaf to the left, trying to free up at
* least data_size bytes. returns zero if the push worked, nonzero otherwise
*/
static int push_leaf_left(struct btrfs_trans_handle *trans, struct btrfs_root
*root, struct btrfs_path *path, int data_size)
{
struct buffer_head *right_buf = path->nodes[0];
struct btrfs_leaf *right = btrfs_buffer_leaf(right_buf);
struct buffer_head *t;
struct btrfs_leaf *left;
int slot;
int i;
int free_space;
int push_space = 0;
int push_items = 0;
struct btrfs_item *item;
u32 old_left_nritems;
int ret = 0;
int wret;
slot = path->slots[1];
if (slot == 0) {
return 1;
}
if (!path->nodes[1]) {
return 1;
}
t = read_tree_block(root,
btrfs_node_blockptr(btrfs_buffer_node(path->nodes[1]), slot - 1));
left = btrfs_buffer_leaf(t);
free_space = btrfs_leaf_free_space(root, left);
if (free_space < data_size + sizeof(struct btrfs_item)) {
btrfs_block_release(root, t);
return 1;
}
/* cow and double check */
btrfs_cow_block(trans, root, t, path->nodes[1], slot - 1, &t);
left = btrfs_buffer_leaf(t);
free_space = btrfs_leaf_free_space(root, left);
if (free_space < data_size + sizeof(struct btrfs_item)) {
btrfs_block_release(root, t);
return 1;
}
if (btrfs_header_nritems(&right->header) == 0) {
btrfs_block_release(root, t);
return 1;
}
for (i = 0; i < btrfs_header_nritems(&right->header) - 1; i++) {
item = right->items + i;
if (path->slots[0] == i)
push_space += data_size + sizeof(*item);
if (btrfs_item_size(item) + sizeof(*item) + push_space >
free_space)
break;
push_items++;
push_space += btrfs_item_size(item) + sizeof(*item);
}
if (push_items == 0) {
btrfs_block_release(root, t);
return 1;
}
if (push_items == btrfs_header_nritems(&right->header))
WARN_ON(1);
/* push data from right to left */
btrfs_memcpy(root, left, left->items +
btrfs_header_nritems(&left->header),
right->items, push_items * sizeof(struct btrfs_item));
push_space = BTRFS_LEAF_DATA_SIZE(root) -
btrfs_item_offset(right->items + push_items -1);
btrfs_memcpy(root, left, btrfs_leaf_data(left) +
leaf_data_end(root, left) - push_space,
btrfs_leaf_data(right) +
btrfs_item_offset(right->items + push_items - 1),
push_space);
old_left_nritems = btrfs_header_nritems(&left->header);
BUG_ON(old_left_nritems < 0);
for (i = old_left_nritems; i < old_left_nritems + push_items; i++) {
u32 ioff = btrfs_item_offset(left->items + i);
btrfs_set_item_offset(left->items + i, ioff -
(BTRFS_LEAF_DATA_SIZE(root) -
btrfs_item_offset(left->items +
old_left_nritems - 1)));
}
btrfs_set_header_nritems(&left->header, old_left_nritems + push_items);
/* fixup right node */
push_space = btrfs_item_offset(right->items + push_items - 1) -
leaf_data_end(root, right);
btrfs_memmove(root, right, btrfs_leaf_data(right) +
BTRFS_LEAF_DATA_SIZE(root) - push_space,
btrfs_leaf_data(right) +
leaf_data_end(root, right), push_space);
btrfs_memmove(root, right, right->items, right->items + push_items,
(btrfs_header_nritems(&right->header) - push_items) *
sizeof(struct btrfs_item));
btrfs_set_header_nritems(&right->header,
btrfs_header_nritems(&right->header) -
push_items);
push_space = BTRFS_LEAF_DATA_SIZE(root);
for (i = 0; i < btrfs_header_nritems(&right->header); i++) {
btrfs_set_item_offset(right->items + i, push_space -
btrfs_item_size(right->items + i));
push_space = btrfs_item_offset(right->items + i);
}
btrfs_mark_buffer_dirty(t);
btrfs_mark_buffer_dirty(right_buf);
wret = fixup_low_keys(trans, root, path, &right->items[0].key, 1);
if (wret)
ret = wret;
/* then fixup the leaf pointer in the path */
if (path->slots[0] < push_items) {
path->slots[0] += old_left_nritems;
btrfs_block_release(root, path->nodes[0]);
path->nodes[0] = t;
path->slots[1] -= 1;
} else {
btrfs_block_release(root, t);
path->slots[0] -= push_items;
}
BUG_ON(path->slots[0] < 0);
return ret;
}
/*
* split the path's leaf in two, making sure there is at least data_size
* available for the resulting leaf level of the path.
*
* returns 0 if all went well and < 0 on failure.
*/
static int split_leaf(struct btrfs_trans_handle *trans, struct btrfs_root
*root, struct btrfs_key *ins_key,
struct btrfs_path *path, int data_size)
{
struct buffer_head *l_buf;
struct btrfs_leaf *l;
u32 nritems;
int mid;
int slot;
struct btrfs_leaf *right;
struct buffer_head *right_buffer;
int space_needed = data_size + sizeof(struct btrfs_item);
int data_copy_size;
int rt_data_off;
int i;
int ret = 0;
int wret;
int double_split = 0;
struct btrfs_disk_key disk_key;
/* first try to make some room by pushing left and right */
wret = push_leaf_left(trans, root, path, data_size);
if (wret < 0)
return wret;
if (wret) {
wret = push_leaf_right(trans, root, path, data_size);
if (wret < 0)
return wret;
}
l_buf = path->nodes[0];
l = btrfs_buffer_leaf(l_buf);
/* did the pushes work? */
if (btrfs_leaf_free_space(root, l) >=
sizeof(struct btrfs_item) + data_size)
return 0;
if (!path->nodes[1]) {
ret = insert_new_root(trans, root, path, 1);
if (ret)
return ret;
}
slot = path->slots[0];
nritems = btrfs_header_nritems(&l->header);
mid = (nritems + 1)/ 2;
right_buffer = btrfs_alloc_free_block(trans, root, l_buf->b_blocknr);
BUG_ON(!right_buffer);
right = btrfs_buffer_leaf(right_buffer);
memset(&right->header, 0, sizeof(right->header));
btrfs_set_header_blocknr(&right->header, bh_blocknr(right_buffer));
btrfs_set_header_generation(&right->header, trans->transid);
btrfs_set_header_owner(&right->header, root->root_key.objectid);
btrfs_set_header_level(&right->header, 0);
memcpy(right->header.fsid, root->fs_info->disk_super->fsid,
sizeof(right->header.fsid));
if (mid <= slot) {
if (nritems == 1 ||
leaf_space_used(l, mid, nritems - mid) + space_needed >
BTRFS_LEAF_DATA_SIZE(root)) {
if (slot >= nritems) {
btrfs_cpu_key_to_disk(&disk_key, ins_key);
btrfs_set_header_nritems(&right->header, 0);
wret = insert_ptr(trans, root, path,
&disk_key,
bh_blocknr(right_buffer),
path->slots[1] + 1, 1);
if (wret)
ret = wret;
btrfs_block_release(root, path->nodes[0]);
path->nodes[0] = right_buffer;
path->slots[0] = 0;
path->slots[1] += 1;
return ret;
}
mid = slot;
double_split = 1;
}
} else {
if (leaf_space_used(l, 0, mid + 1) + space_needed >
BTRFS_LEAF_DATA_SIZE(root)) {
if (slot == 0) {
btrfs_cpu_key_to_disk(&disk_key, ins_key);
btrfs_set_header_nritems(&right->header, 0);
wret = insert_ptr(trans, root, path,
&disk_key,
bh_blocknr(right_buffer),
path->slots[1] - 1, 1);
if (wret)
ret = wret;
btrfs_block_release(root, path->nodes[0]);
path->nodes[0] = right_buffer;
path->slots[0] = 0;
path->slots[1] -= 1;
if (path->slots[1] == 0) {
wret = fixup_low_keys(trans, root,
path, &disk_key, 1);
if (wret)
ret = wret;
}
return ret;
}
mid = slot;
double_split = 1;
}
}
btrfs_set_header_nritems(&right->header, nritems - mid);
data_copy_size = btrfs_item_end(l->items + mid) -
leaf_data_end(root, l);
btrfs_memcpy(root, right, right->items, l->items + mid,
(nritems - mid) * sizeof(struct btrfs_item));
btrfs_memcpy(root, right,
btrfs_leaf_data(right) + BTRFS_LEAF_DATA_SIZE(root) -
data_copy_size, btrfs_leaf_data(l) +
leaf_data_end(root, l), data_copy_size);
rt_data_off = BTRFS_LEAF_DATA_SIZE(root) -
btrfs_item_end(l->items + mid);
for (i = 0; i < btrfs_header_nritems(&right->header); i++) {
u32 ioff = btrfs_item_offset(right->items + i);
btrfs_set_item_offset(right->items + i, ioff + rt_data_off);
}
btrfs_set_header_nritems(&l->header, mid);
ret = 0;
wret = insert_ptr(trans, root, path, &right->items[0].key,
bh_blocknr(right_buffer), path->slots[1] + 1, 1);
if (wret)
ret = wret;
btrfs_mark_buffer_dirty(right_buffer);
btrfs_mark_buffer_dirty(l_buf);
BUG_ON(path->slots[0] != slot);
if (mid <= slot) {
btrfs_block_release(root, path->nodes[0]);
path->nodes[0] = right_buffer;
path->slots[0] -= mid;
path->slots[1] += 1;
} else
btrfs_block_release(root, right_buffer);
BUG_ON(path->slots[0] < 0);
if (!double_split)
return ret;
right_buffer = btrfs_alloc_free_block(trans, root, l_buf->b_blocknr);
BUG_ON(!right_buffer);
right = btrfs_buffer_leaf(right_buffer);
memset(&right->header, 0, sizeof(right->header));
btrfs_set_header_blocknr(&right->header, bh_blocknr(right_buffer));
btrfs_set_header_generation(&right->header, trans->transid);
btrfs_set_header_owner(&right->header, root->root_key.objectid);
btrfs_set_header_level(&right->header, 0);
memcpy(right->header.fsid, root->fs_info->disk_super->fsid,
sizeof(right->header.fsid));
btrfs_cpu_key_to_disk(&disk_key, ins_key);
btrfs_set_header_nritems(&right->header, 0);
wret = insert_ptr(trans, root, path,
&disk_key,
bh_blocknr(right_buffer),
path->slots[1], 1);
if (wret)
ret = wret;
if (path->slots[1] == 0) {
wret = fixup_low_keys(trans, root, path, &disk_key, 1);
if (wret)
ret = wret;
}
btrfs_block_release(root, path->nodes[0]);
path->nodes[0] = right_buffer;
path->slots[0] = 0;
check_node(root, path, 1);
check_leaf(root, path, 0);
return ret;
}
int btrfs_truncate_item(struct btrfs_trans_handle *trans,
struct btrfs_root *root,
struct btrfs_path *path,
u32 new_size)
{
int ret = 0;
int slot;
int slot_orig;
struct btrfs_leaf *leaf;
struct buffer_head *leaf_buf;
u32 nritems;
unsigned int data_end;
unsigned int old_data_start;
unsigned int old_size;
unsigned int size_diff;
int i;
slot_orig = path->slots[0];
leaf_buf = path->nodes[0];
leaf = btrfs_buffer_leaf(leaf_buf);
nritems = btrfs_header_nritems(&leaf->header);
data_end = leaf_data_end(root, leaf);
slot = path->slots[0];
old_data_start = btrfs_item_offset(leaf->items + slot);
old_size = btrfs_item_size(leaf->items + slot);
BUG_ON(old_size <= new_size);
size_diff = old_size - new_size;
BUG_ON(slot < 0);
BUG_ON(slot >= nritems);
/*
* item0..itemN ... dataN.offset..dataN.size .. data0.size
*/
/* first correct the data pointers */
for (i = slot; i < nritems; i++) {
u32 ioff = btrfs_item_offset(leaf->items + i);
btrfs_set_item_offset(leaf->items + i,
ioff + size_diff);
}
/* shift the data */
btrfs_memmove(root, leaf, btrfs_leaf_data(leaf) +
data_end + size_diff, btrfs_leaf_data(leaf) +
data_end, old_data_start + new_size - data_end);
btrfs_set_item_size(leaf->items + slot, new_size);
btrfs_mark_buffer_dirty(leaf_buf);
ret = 0;
if (btrfs_leaf_free_space(root, leaf) < 0)
BUG();
check_leaf(root, path, 0);
return ret;
}
int btrfs_extend_item(struct btrfs_trans_handle *trans, struct btrfs_root
*root, struct btrfs_path *path, u32 data_size)
{
int ret = 0;
int slot;
int slot_orig;
struct btrfs_leaf *leaf;
struct buffer_head *leaf_buf;
u32 nritems;
unsigned int data_end;
unsigned int old_data;
unsigned int old_size;
int i;
slot_orig = path->slots[0];
leaf_buf = path->nodes[0];
leaf = btrfs_buffer_leaf(leaf_buf);
nritems = btrfs_header_nritems(&leaf->header);
data_end = leaf_data_end(root, leaf);
if (btrfs_leaf_free_space(root, leaf) < data_size)
BUG();
slot = path->slots[0];
old_data = btrfs_item_end(leaf->items + slot);
BUG_ON(slot < 0);
BUG_ON(slot >= nritems);
/*
* item0..itemN ... dataN.offset..dataN.size .. data0.size
*/
/* first correct the data pointers */
for (i = slot; i < nritems; i++) {
u32 ioff = btrfs_item_offset(leaf->items + i);
btrfs_set_item_offset(leaf->items + i,
ioff - data_size);
}
/* shift the data */
btrfs_memmove(root, leaf, btrfs_leaf_data(leaf) +
data_end - data_size, btrfs_leaf_data(leaf) +
data_end, old_data - data_end);
data_end = old_data;
old_size = btrfs_item_size(leaf->items + slot);
btrfs_set_item_size(leaf->items + slot, old_size + data_size);
btrfs_mark_buffer_dirty(leaf_buf);
ret = 0;
if (btrfs_leaf_free_space(root, leaf) < 0)
BUG();
check_leaf(root, path, 0);
return ret;
}
/*
* Given a key and some data, insert an item into the tree.
* This does all the path init required, making room in the tree if needed.
*/
int btrfs_insert_empty_item(struct btrfs_trans_handle *trans, struct btrfs_root
*root, struct btrfs_path *path, struct btrfs_key
*cpu_key, u32 data_size)
{
int ret = 0;
int slot;
int slot_orig;
struct btrfs_leaf *leaf;
struct buffer_head *leaf_buf;
u32 nritems;
unsigned int data_end;
struct btrfs_disk_key disk_key;
btrfs_cpu_key_to_disk(&disk_key, cpu_key);
/* create a root if there isn't one */
if (!root->node)
BUG();
ret = btrfs_search_slot(trans, root, cpu_key, path, data_size, 1);
if (ret == 0) {
return -EEXIST;
}
if (ret < 0)
goto out;
slot_orig = path->slots[0];
leaf_buf = path->nodes[0];
leaf = btrfs_buffer_leaf(leaf_buf);
nritems = btrfs_header_nritems(&leaf->header);
data_end = leaf_data_end(root, leaf);
if (btrfs_leaf_free_space(root, leaf) <
sizeof(struct btrfs_item) + data_size) {
BUG();
}
slot = path->slots[0];
BUG_ON(slot < 0);
if (slot != nritems) {
int i;
unsigned int old_data = btrfs_item_end(leaf->items + slot);
/*
* item0..itemN ... dataN.offset..dataN.size .. data0.size
*/
/* first correct the data pointers */
for (i = slot; i < nritems; i++) {
u32 ioff = btrfs_item_offset(leaf->items + i);
btrfs_set_item_offset(leaf->items + i,
ioff - data_size);
}
/* shift the items */
btrfs_memmove(root, leaf, leaf->items + slot + 1,
leaf->items + slot,
(nritems - slot) * sizeof(struct btrfs_item));
/* shift the data */
btrfs_memmove(root, leaf, btrfs_leaf_data(leaf) +
data_end - data_size, btrfs_leaf_data(leaf) +
data_end, old_data - data_end);
data_end = old_data;
}
/* setup the item for the new data */
btrfs_memcpy(root, leaf, &leaf->items[slot].key, &disk_key,
sizeof(struct btrfs_disk_key));
btrfs_set_item_offset(leaf->items + slot, data_end - data_size);
btrfs_set_item_size(leaf->items + slot, data_size);
btrfs_set_header_nritems(&leaf->header, nritems + 1);
btrfs_mark_buffer_dirty(leaf_buf);
ret = 0;
if (slot == 0)
ret = fixup_low_keys(trans, root, path, &disk_key, 1);
if (btrfs_leaf_free_space(root, leaf) < 0)
BUG();
check_leaf(root, path, 0);
out:
return ret;
}
/*
* Given a key and some data, insert an item into the tree.
* This does all the path init required, making room in the tree if needed.
*/
int btrfs_insert_item(struct btrfs_trans_handle *trans, struct btrfs_root
*root, struct btrfs_key *cpu_key, void *data, u32
data_size)
{
int ret = 0;
struct btrfs_path *path;
u8 *ptr;
path = btrfs_alloc_path();
BUG_ON(!path);
btrfs_init_path(path);
ret = btrfs_insert_empty_item(trans, root, path, cpu_key, data_size);
if (!ret) {
ptr = btrfs_item_ptr(btrfs_buffer_leaf(path->nodes[0]),
path->slots[0], u8);
btrfs_memcpy(root, path->nodes[0]->b_data,
ptr, data, data_size);
btrfs_mark_buffer_dirty(path->nodes[0]);
}
btrfs_release_path(root, path);
btrfs_free_path(path);
return ret;
}
/*
* delete the pointer from a given node.
*
* If the delete empties a node, the node is removed from the tree,
* continuing all the way the root if required. The root is converted into
* a leaf if all the nodes are emptied.
*/
static int del_ptr(struct btrfs_trans_handle *trans, struct btrfs_root *root,
struct btrfs_path *path, int level, int slot)
{
struct btrfs_node *node;
struct buffer_head *parent = path->nodes[level];
u32 nritems;
int ret = 0;
int wret;
node = btrfs_buffer_node(parent);
nritems = btrfs_header_nritems(&node->header);
if (slot != nritems -1) {
btrfs_memmove(root, node, node->ptrs + slot,
node->ptrs + slot + 1,
sizeof(struct btrfs_key_ptr) *
(nritems - slot - 1));
}
nritems--;
btrfs_set_header_nritems(&node->header, nritems);
if (nritems == 0 && parent == root->node) {
struct btrfs_header *header = btrfs_buffer_header(root->node);
BUG_ON(btrfs_header_level(header) != 1);
/* just turn the root into a leaf and break */
btrfs_set_header_level(header, 0);
} else if (slot == 0) {
wret = fixup_low_keys(trans, root, path, &node->ptrs[0].key,
level + 1);
if (wret)
ret = wret;
}
btrfs_mark_buffer_dirty(parent);
return ret;
}
/*
* delete the item at the leaf level in path. If that empties
* the leaf, remove it from the tree
*/
int btrfs_del_item(struct btrfs_trans_handle *trans, struct btrfs_root *root,
struct btrfs_path *path)
{
int slot;
struct btrfs_leaf *leaf;
struct buffer_head *leaf_buf;
int doff;
int dsize;
int ret = 0;
int wret;
u32 nritems;
leaf_buf = path->nodes[0];
leaf = btrfs_buffer_leaf(leaf_buf);
slot = path->slots[0];
doff = btrfs_item_offset(leaf->items + slot);
dsize = btrfs_item_size(leaf->items + slot);
nritems = btrfs_header_nritems(&leaf->header);
if (slot != nritems - 1) {
int i;
int data_end = leaf_data_end(root, leaf);
btrfs_memmove(root, leaf, btrfs_leaf_data(leaf) +
data_end + dsize,
btrfs_leaf_data(leaf) + data_end,
doff - data_end);
for (i = slot + 1; i < nritems; i++) {
u32 ioff = btrfs_item_offset(leaf->items + i);
btrfs_set_item_offset(leaf->items + i, ioff + dsize);
}
btrfs_memmove(root, leaf, leaf->items + slot,
leaf->items + slot + 1,
sizeof(struct btrfs_item) *
(nritems - slot - 1));
}
btrfs_set_header_nritems(&leaf->header, nritems - 1);
nritems--;
/* delete the leaf if we've emptied it */
if (nritems == 0) {
if (leaf_buf == root->node) {
btrfs_set_header_level(&leaf->header, 0);
} else {
clean_tree_block(trans, root, leaf_buf);
wait_on_buffer(leaf_buf);
wret = del_ptr(trans, root, path, 1, path->slots[1]);
if (wret)
ret = wret;
wret = btrfs_free_extent(trans, root,
bh_blocknr(leaf_buf), 1, 1);
if (wret)
ret = wret;
}
} else {
int used = leaf_space_used(leaf, 0, nritems);
if (slot == 0) {
wret = fixup_low_keys(trans, root, path,
&leaf->items[0].key, 1);
if (wret)
ret = wret;
}
/* delete the leaf if it is mostly empty */
if (used < BTRFS_LEAF_DATA_SIZE(root) / 3) {
/* push_leaf_left fixes the path.
* make sure the path still points to our leaf
* for possible call to del_ptr below
*/
slot = path->slots[1];
get_bh(leaf_buf);
wret = push_leaf_left(trans, root, path, 1);
if (wret < 0)
ret = wret;
if (path->nodes[0] == leaf_buf &&
btrfs_header_nritems(&leaf->header)) {
wret = push_leaf_right(trans, root, path, 1);
if (wret < 0)
ret = wret;
}
if (btrfs_header_nritems(&leaf->header) == 0) {
u64 blocknr = bh_blocknr(leaf_buf);
clean_tree_block(trans, root, leaf_buf);
wait_on_buffer(leaf_buf);
wret = del_ptr(trans, root, path, 1, slot);
if (wret)
ret = wret;
btrfs_block_release(root, leaf_buf);
wret = btrfs_free_extent(trans, root, blocknr,
1, 1);
if (wret)
ret = wret;
} else {
btrfs_mark_buffer_dirty(leaf_buf);
btrfs_block_release(root, leaf_buf);
}
} else {
btrfs_mark_buffer_dirty(leaf_buf);
}
}
return ret;
}
/*
* walk up the tree as far as required to find the next leaf.
* returns 0 if it found something or 1 if there are no greater leaves.
* returns < 0 on io errors.
*/
int btrfs_next_leaf(struct btrfs_root *root, struct btrfs_path *path)
{
int slot;
int level = 1;
u64 blocknr;
struct buffer_head *c;
struct btrfs_node *c_node;
struct buffer_head *next = NULL;
while(level < BTRFS_MAX_LEVEL) {
if (!path->nodes[level])
return 1;
slot = path->slots[level] + 1;
c = path->nodes[level];
c_node = btrfs_buffer_node(c);
if (slot >= btrfs_header_nritems(&c_node->header)) {
level++;
continue;
}
blocknr = btrfs_node_blockptr(c_node, slot);
if (next)
btrfs_block_release(root, next);
next = read_tree_block(root, blocknr);
break;
}
path->slots[level] = slot;
while(1) {
level--;
c = path->nodes[level];
btrfs_block_release(root, c);
path->nodes[level] = next;
path->slots[level] = 0;
if (!level)
break;
next = read_tree_block(root,
btrfs_node_blockptr(btrfs_buffer_node(next), 0));
}
return 0;
}
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