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Btrfs: merge on the way down during deletes

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Signed-off-by: Chris Mason <chris.mason@oracle.com>
This commit is contained in:
Chris Mason 2007-03-01 12:04:21 -05:00 committed by David Woodhouse
parent 0f70abe2b3
commit bb8039515d
1 changed files with 200 additions and 220 deletions
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420
fs/btrfs/ctree.c
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@ -10,11 +10,10 @@ static int split_node(struct ctree_root *root, struct ctree_path *path,
int level); int level);
static int split_leaf(struct ctree_root *root, struct ctree_path *path, static int split_leaf(struct ctree_root *root, struct ctree_path *path,
int data_size); int data_size);
static int push_node_left(struct ctree_root *root, struct ctree_path *path, static int push_node_left(struct ctree_root *root, struct tree_buffer *dst,
int level); struct tree_buffer *src);
static int push_node_right(struct ctree_root *root, static int del_ptr(struct ctree_root *root, struct ctree_path *path, int level,
struct ctree_path *path, int level); int slot);
static int del_ptr(struct ctree_root *root, struct ctree_path *path, int level);
inline void init_path(struct ctree_path *p) inline void init_path(struct ctree_path *p)
{ {
@ -192,6 +191,138 @@ int bin_search(struct node *c, struct key *key, int *slot)
return -1; return -1;
} }
struct tree_buffer *read_node_slot(struct ctree_root *root,
struct tree_buffer *parent_buf,
int slot)
{
struct node *node = &parent_buf->node;
if (slot < 0)
return NULL;
if (slot >= node->header.nritems)
return NULL;
return read_tree_block(root, node->blockptrs[slot]);
}
static int balance_level(struct ctree_root *root, struct ctree_path *path,
int level)
{
struct tree_buffer *right_buf;
struct tree_buffer *mid_buf;
struct tree_buffer *left_buf;
struct tree_buffer *parent_buf = NULL;
struct node *right = NULL;
struct node *mid;
struct node *left = NULL;
struct node *parent = NULL;
int ret = 0;
int wret;
int pslot;
int used = 0;
int count;
int orig_slot = path->slots[level];
if (level == 0)
return 0;
mid_buf = path->nodes[level];
mid = &mid_buf->node;
if (level < MAX_LEVEL - 1)
parent_buf = path->nodes[level + 1];
pslot = path->slots[level + 1];
if (!parent_buf) {
struct tree_buffer *child;
u64 blocknr = mid_buf->blocknr;
if (mid->header.nritems != 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;
/* once for the path */
tree_block_release(root, mid_buf);
/* once for the root ptr */
tree_block_release(root, mid_buf);
return free_extent(root, blocknr, 1);
}
parent = &parent_buf->node;
if (mid->header.nritems > NODEPTRS_PER_BLOCK / 4)
return 0;
// print_tree(root, root->node);
left_buf = read_node_slot(root, parent_buf, pslot - 1);
right_buf = read_node_slot(root, parent_buf, pslot + 1);
if (right_buf) {
right = &right_buf->node;
used = right->header.nritems;
count = 1;
}
if (left_buf) {
left = &left_buf->node;
used += left->header.nritems;
orig_slot += left->header.nritems;
count++;
}
if (left_buf)
push_node_left(root, left_buf, mid_buf);
if (right_buf) {
push_node_left(root, mid_buf, right_buf);
if (right->header.nritems == 0) {
u64 blocknr = right_buf->blocknr;
tree_block_release(root, right_buf);
right_buf = NULL;
right = NULL;
wret = del_ptr(root, path, level + 1, pslot + 1);
if (wret)
ret = wret;
wret = free_extent(root, blocknr, 1);
if (wret)
ret = wret;
} else {
memcpy(parent->keys + pslot + 1, right->keys,
sizeof(struct key));
}
}
if (mid->header.nritems == 0) {
u64 blocknr = mid_buf->blocknr;
tree_block_release(root, mid_buf);
mid_buf = NULL;
mid = NULL;
wret = del_ptr(root, path, level + 1, pslot);
if (wret)
ret = wret;
wret = free_extent(root, blocknr, 1);
if (wret)
ret = wret;
} else
memcpy(parent->keys + pslot, mid->keys, sizeof(struct key));
if (left_buf) {
if (left->header.nritems >= orig_slot) {
left_buf->count++; // released below
path->nodes[level] = left_buf;
path->slots[level + 1] -= 1;
path->slots[level] = orig_slot;
if (mid_buf)
tree_block_release(root, mid_buf);
} else {
orig_slot -= left->header.nritems;
path->slots[level] = orig_slot;
}
}
if (right_buf)
tree_block_release(root, right_buf);
if (left_buf)
tree_block_release(root, left_buf);
return ret;
}
/* /*
* look for key in the tree. path is filled in with nodes along the way * 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 * if key is found, we return zero and you can find the item in the leaf
@ -208,12 +339,14 @@ int bin_search(struct node *c, struct key *key, int *slot)
int search_slot(struct ctree_root *root, struct key *key, int search_slot(struct ctree_root *root, struct key *key,
struct ctree_path *p, int ins_len) struct ctree_path *p, int ins_len)
{ {
struct tree_buffer *b = root->node; struct tree_buffer *b;
struct node *c; struct node *c;
int slot; int slot;
int ret; int ret;
int level; int level;
again:
b = root->node;
b->count++; b->count++;
while (b) { while (b) {
c = &b->node; c = &b->node;
@ -236,9 +369,17 @@ int search_slot(struct ctree_root *root, struct key *key,
b = p->nodes[level]; b = p->nodes[level];
c = &b->node; c = &b->node;
slot = p->slots[level]; slot = p->slots[level];
} else if (ins_len < 0) {
int sret = balance_level(root, p, level);
if (sret)
return sret;
b = p->nodes[level];
if (!b)
goto again;
c = &b->node;
slot = p->slots[level];
} }
b = read_tree_block(root, c->blockptrs[slot]); b = read_tree_block(root, c->blockptrs[slot]);
continue;
} else { } else {
struct leaf *l = (struct leaf *)c; struct leaf *l = (struct leaf *)c;
p->slots[level] = slot; p->slots[level] = slot;
@ -249,9 +390,11 @@ int search_slot(struct ctree_root *root, struct key *key,
if (sret) if (sret)
return sret; return sret;
} }
BUG_ON(root->node->count == 1);
return ret; return ret;
} }
} }
BUG_ON(root->node->count == 1);
return 1; return 1;
} }
@ -301,161 +444,47 @@ static int fixup_low_keys(struct ctree_root *root,
* returns 0 if some ptrs were pushed left, < 0 if there was some horrible * 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. * error, and > 0 if there was no room in the left hand block.
*/ */
static int push_node_left(struct ctree_root *root, struct ctree_path *path, static int push_node_left(struct ctree_root *root, struct tree_buffer *dst_buf,
int level) struct tree_buffer *src_buf)
{ {
int slot; struct node *src = &src_buf->node;
struct node *left; struct node *dst = &dst_buf->node;
struct node *right;
int push_items = 0; int push_items = 0;
int left_nritems; int src_nritems;
int right_nritems; int dst_nritems;
struct tree_buffer *t;
struct tree_buffer *right_buf;
int ret = 0; int ret = 0;
int wret; int wret;
if (level == MAX_LEVEL - 1 || path->nodes[level + 1] == 0)
return 1;
slot = path->slots[level + 1];
if (slot == 0)
return 1;
t = read_tree_block(root,
path->nodes[level + 1]->node.blockptrs[slot - 1]);
left = &t->node;
right_buf = path->nodes[level];
right = &right_buf->node;
left_nritems = left->header.nritems;
right_nritems = right->header.nritems;
push_items = NODEPTRS_PER_BLOCK - (left_nritems + 1);
if (push_items <= 0) {
tree_block_release(root, t);
return 1;
}
if (right_nritems < push_items)
push_items = right_nritems;
memcpy(left->keys + left_nritems, right->keys,
push_items * sizeof(struct key));
memcpy(left->blockptrs + left_nritems, right->blockptrs,
push_items * sizeof(u64));
memmove(right->keys, right->keys + push_items,
(right_nritems - push_items) * sizeof(struct key));
memmove(right->blockptrs, right->blockptrs + push_items,
(right_nritems - push_items) * sizeof(u64));
right->header.nritems -= push_items;
left->header.nritems += push_items;
/* adjust the pointers going up the tree */
wret = fixup_low_keys(root, path, right->keys, level + 1);
if (wret < 0)
ret = wret;
wret = write_tree_block(root, t);
if (wret < 0)
ret = wret;
wret = write_tree_block(root, right_buf);
if (wret < 0)
ret = wret;
/* then fixup the leaf pointer in the path */
if (path->slots[level] < push_items) {
path->slots[level] += left_nritems;
tree_block_release(root, path->nodes[level]);
path->nodes[level] = t;
path->slots[level + 1] -= 1;
} else {
path->slots[level] -= push_items;
tree_block_release(root, t);
}
return ret;
}
/*
* try to push data from one node into the next node right in the
* tree. The src node is found at specified level in the path.
* If some bytes were pushed, return 0, otherwise return 1.
*
* Lower nodes/leaves in the path are not touched, higher nodes may
* be modified to reflect the push.
*
* The path is altered to reflect the push.
*
* 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.
*/
static int push_node_right(struct ctree_root *root, struct ctree_path *path,
int level)
{
int slot;
struct tree_buffer *t;
struct tree_buffer *src_buffer;
struct node *dst;
struct node *src;
int push_items = 0;
int dst_nritems;
int src_nritems;
/* can't push from the root */
if (level == MAX_LEVEL - 1 || path->nodes[level + 1] == 0)
return 1;
/* only try to push inside the node higher up */
slot = path->slots[level + 1];
if (slot == NODEPTRS_PER_BLOCK - 1)
return 1;
if (slot >= path->nodes[level + 1]->node.header.nritems -1)
return 1;
t = read_tree_block(root,
path->nodes[level + 1]->node.blockptrs[slot + 1]);
dst = &t->node;
src_buffer = path->nodes[level];
src = &src_buffer->node;
dst_nritems = dst->header.nritems;
src_nritems = src->header.nritems; src_nritems = src->header.nritems;
push_items = NODEPTRS_PER_BLOCK - (dst_nritems + 1); dst_nritems = dst->header.nritems;
push_items = NODEPTRS_PER_BLOCK - dst_nritems;
if (push_items <= 0) { if (push_items <= 0) {
tree_block_release(root, t);
return 1; return 1;
} }
if (src_nritems < push_items) if (src_nritems < push_items)
push_items = src_nritems; push_items =src_nritems;
memmove(dst->keys + push_items, dst->keys, memcpy(dst->keys + dst_nritems, src->keys,
dst_nritems * sizeof(struct key));
memcpy(dst->keys, src->keys + src_nritems - push_items,
push_items * sizeof(struct key)); push_items * sizeof(struct key));
memcpy(dst->blockptrs + dst_nritems, src->blockptrs,
memmove(dst->blockptrs + push_items, dst->blockptrs,
dst_nritems * sizeof(u64));
memcpy(dst->blockptrs, src->blockptrs + src_nritems - push_items,
push_items * sizeof(u64)); push_items * sizeof(u64));
if (push_items < src_nritems) {
memmove(src->keys, src->keys + push_items,
(src_nritems - push_items) * sizeof(struct key));
memmove(src->blockptrs, src->blockptrs + push_items,
(src_nritems - push_items) * sizeof(u64));
}
src->header.nritems -= push_items; src->header.nritems -= push_items;
dst->header.nritems += push_items; dst->header.nritems += push_items;
/* adjust the pointers going up the tree */ wret = write_tree_block(root, src_buf);
memcpy(path->nodes[level + 1]->node.keys + path->slots[level + 1] + 1, if (wret < 0)
dst->keys, sizeof(struct key)); ret = wret;
write_tree_block(root, path->nodes[level + 1]); wret = write_tree_block(root, dst_buf);
write_tree_block(root, t); if (wret < 0)
write_tree_block(root, src_buffer); ret = wret;
return ret;
/* then fixup the pointers in the path */
if (path->slots[level] >= src->header.nritems) {
path->slots[level] -= src->header.nritems;
tree_block_release(root, path->nodes[level]);
path->nodes[level] = t;
path->slots[level + 1] += 1;
} else {
tree_block_release(root, t);
}
return 0;
} }
/* /*
@ -558,16 +587,6 @@ static int split_node(struct ctree_root *root, struct ctree_path *path,
int ret; int ret;
int wret; int wret;
ret = push_node_left(root, path, level);
if (!ret)
return 0;
if (ret < 0)
return ret;
ret = push_node_right(root, path, level);
if (!ret)
return 0;
if (ret < 0)
return ret;
t = path->nodes[level]; t = path->nodes[level];
c = &t->node; c = &t->node;
if (t == root->node) { if (t == root->node) {
@ -1011,6 +1030,7 @@ int insert_item(struct ctree_root *root, struct key *key,
if (leaf_free_space(leaf) < 0) if (leaf_free_space(leaf) < 0)
BUG(); BUG();
check_leaf(&path, 0);
release_path(root, &path); release_path(root, &path);
return ret; return ret;
} }
@ -1022,77 +1042,38 @@ int insert_item(struct ctree_root *root, struct key *key,
* continuing all the way the root if required. The root is converted into * continuing all the way the root if required. The root is converted into
* a leaf if all the nodes are emptied. * a leaf if all the nodes are emptied.
*/ */
static int del_ptr(struct ctree_root *root, struct ctree_path *path, int level) static int del_ptr(struct ctree_root *root, struct ctree_path *path, int level,
int slot)
{ {
int slot;
struct tree_buffer *t;
struct node *node; struct node *node;
struct tree_buffer *parent = path->nodes[level];
int nritems; int nritems;
u64 blocknr;
int wret;
int ret = 0; int ret = 0;
int wret;
while(1) { node = &parent->node;
t = path->nodes[level]; nritems = node->header.nritems;
if (!t)
break;
node = &t->node;
slot = path->slots[level];
nritems = node->header.nritems;
if (slot != nritems -1) { if (slot != nritems -1) {
memmove(node->keys + slot, node->keys + slot + 1, memmove(node->keys + slot, node->keys + slot + 1,
sizeof(struct key) * (nritems - slot - 1)); sizeof(struct key) * (nritems - slot - 1));
memmove(node->blockptrs + slot, memmove(node->blockptrs + slot,
node->blockptrs + slot + 1, node->blockptrs + slot + 1,
sizeof(u64) * (nritems - slot - 1)); sizeof(u64) * (nritems - slot - 1));
} }
node->header.nritems--; node->header.nritems--;
blocknr = t->blocknr; if (node->header.nritems == 0 && parent == root->node) {
write_tree_block(root, t); BUG_ON(node_level(root->node->node.header.flags) != 1);
if (node->header.nritems != 0) { /* just turn the root into a leaf and break */
int tslot; root->node->node.header.flags = node_level(0);
if (slot == 0) { } else if (slot == 0) {
wret = fixup_low_keys(root, path, wret = fixup_low_keys(root, path, node->keys, level + 1);
node->keys,
level + 1);
if (wret)
ret = wret;
}
tslot = path->slots[level + 1];
t->count++;
wret = push_node_left(root, path, level);
if (wret < 0) {
ret = wret;
break;
}
if (node->header.nritems != 0) {
wret = push_node_right(root, path, level);
if (wret < 0) {
ret = wret;
break;
}
}
path->slots[level + 1] = tslot;
if (node->header.nritems != 0) {
tree_block_release(root, t);
break;
}
tree_block_release(root, t);
}
if (t == root->node) {
/* just turn the root into a leaf and break */
root->node->node.header.flags = node_level(0);
write_tree_block(root, t);
break;
}
level++;
wret = free_extent(root, blocknr, 1);
if (wret) if (wret)
ret = wret; ret = wret;
if (!path->nodes[level])
BUG();
} }
wret = write_tree_block(root, parent);
if (wret)
ret = wret;
return ret; return ret;
} }
@ -1135,7 +1116,7 @@ int del_item(struct ctree_root *root, struct ctree_path *path)
leaf->header.flags = node_level(0); leaf->header.flags = node_level(0);
write_tree_block(root, leaf_buf); write_tree_block(root, leaf_buf);
} else { } else {
wret = del_ptr(root, path, 1); wret = del_ptr(root, path, 1, path->slots[1]);
if (wret) if (wret)
ret = wret; ret = wret;
wret = free_extent(root, leaf_buf->blocknr, 1); wret = free_extent(root, leaf_buf->blocknr, 1);
@ -1172,8 +1153,7 @@ int del_item(struct ctree_root *root, struct ctree_path *path)
} }
if (leaf->header.nritems == 0) { if (leaf->header.nritems == 0) {
u64 blocknr = leaf_buf->blocknr; u64 blocknr = leaf_buf->blocknr;
path->slots[1] = slot; wret = del_ptr(root, path, 1, slot);
wret = del_ptr(root, path, 1);
if (wret) if (wret)
ret = wret; ret = wret;
tree_block_release(root, leaf_buf); tree_block_release(root, leaf_buf);