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Btrfs: early reference counting
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Signed-off-by: Chris Mason <chris.mason@oracle.com>
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Chris Mason authored and David Woodhouse committed Mar 2, 2007
1 parent 77ce684 commit 02217ed
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Showing 6 changed files with 145 additions and 80 deletions.
153 changes: 88 additions & 65 deletions fs/btrfs/ctree.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -34,6 +34,37 @@ void release_path(struct ctree_root *root, struct ctree_path *p)
memset(p, 0, sizeof(*p));
}

int btrfs_cow_block(struct ctree_root *root,
struct tree_buffer *buf,
struct tree_buffer *parent,
int parent_slot,
struct tree_buffer **cow_ret)
{
struct tree_buffer *cow;

if (!list_empty(&buf->dirty)) {
*cow_ret = buf;
return 0;
}
cow = alloc_free_block(root);
memcpy(&cow->node, &buf->node, sizeof(buf->node));
cow->node.header.blocknr = cow->blocknr;
*cow_ret = cow;
if (buf == root->node) {
root->node = cow;
cow->count++;
tree_block_release(root, buf);
} else {
parent->node.blockptrs[parent_slot] = cow->blocknr;
BUG_ON(list_empty(&parent->dirty));
}
if (0 && root != root->extent_root && !is_leaf(cow->node.header.flags)) {
btrfs_inc_ref(root, cow);
}
tree_block_release(root, buf);
return 0;
}

/*
* The leaf data grows from end-to-front in the node.
* this returns the address of the start of the last item,
Expand Down Expand Up @@ -263,6 +294,8 @@ static int balance_level(struct ctree_root *root, struct ctree_path *path,

/* first, try to make some room in the middle buffer */
if (left_buf) {
btrfs_cow_block(root, left_buf, parent_buf,
pslot - 1, &left_buf);
left = &left_buf->node;
orig_slot += left->header.nritems;
wret = push_node_left(root, left_buf, mid_buf);
Expand All @@ -274,6 +307,8 @@ static int balance_level(struct ctree_root *root, struct ctree_path *path,
* then try to empty the right most buffer into the middle
*/
if (right_buf) {
btrfs_cow_block(root, right_buf, parent_buf,
pslot + 1, &right_buf);
right = &right_buf->node;
wret = push_node_left(root, mid_buf, right_buf);
if (wret < 0)
Expand All @@ -293,9 +328,7 @@ static int balance_level(struct ctree_root *root, struct ctree_path *path,
} else {
memcpy(parent->keys + pslot + 1, right->keys,
sizeof(struct key));
wret = dirty_tree_block(root, parent_buf);
if (wret)
ret = wret;
BUG_ON(list_empty(&parent_buf->dirty));
}
}
if (mid->header.nritems == 1) {
Expand Down Expand Up @@ -330,9 +363,7 @@ static int balance_level(struct ctree_root *root, struct ctree_path *path,
} else {
/* update the parent key to reflect our changes */
memcpy(parent->keys + pslot, mid->keys, sizeof(struct key));
wret = dirty_tree_block(root, parent_buf);
if (wret)
ret = wret;
BUG_ON(list_empty(&parent_buf->dirty));
}

/* update the path */
Expand Down Expand Up @@ -375,9 +406,10 @@ static int balance_level(struct ctree_root *root, struct ctree_path *path,
* possible)
*/
int search_slot(struct ctree_root *root, struct key *key,
struct ctree_path *p, int ins_len)
struct ctree_path *p, int ins_len, int cow)
{
struct tree_buffer *b;
struct tree_buffer *cow_buf;
struct node *c;
int slot;
int ret;
Expand All @@ -387,8 +419,15 @@ int search_slot(struct ctree_root *root, struct key *key,
b = root->node;
b->count++;
while (b) {
level = node_level(b->node.header.flags);
if (cow) {
int wret;
wret = btrfs_cow_block(root, b, p->nodes[level + 1],
p->slots[level + 1], &cow_buf);
b = cow_buf;
}
BUG_ON(!cow && ins_len);
c = &b->node;
level = node_level(c->header.flags);
p->nodes[level] = b;
ret = check_block(p, level);
if (ret)
Expand Down Expand Up @@ -453,17 +492,14 @@ static int fixup_low_keys(struct ctree_root *root,
{
int i;
int ret = 0;
int wret;
for (i = level; i < MAX_LEVEL; i++) {
struct node *t;
int tslot = path->slots[i];
if (!path->nodes[i])
break;
t = &path->nodes[i]->node;
memcpy(t->keys + tslot, key, sizeof(*key));
wret = dirty_tree_block(root, path->nodes[i]);
if (wret)
ret = wret;
BUG_ON(list_empty(&path->nodes[i]->dirty));
if (tslot != 0)
break;
}
Expand All @@ -486,7 +522,6 @@ static int push_node_left(struct ctree_root *root, struct tree_buffer *dst_buf,
int src_nritems;
int dst_nritems;
int ret = 0;
int wret;

src_nritems = src->header.nritems;
dst_nritems = dst->header.nritems;
Expand All @@ -511,13 +546,8 @@ static int push_node_left(struct ctree_root *root, struct tree_buffer *dst_buf,
src->header.nritems -= push_items;
dst->header.nritems += push_items;

wret = dirty_tree_block(root, src_buf);
if (wret < 0)
ret = wret;

wret = dirty_tree_block(root, dst_buf);
if (wret < 0)
ret = wret;
BUG_ON(list_empty(&src_buf->dirty));
BUG_ON(list_empty(&dst_buf->dirty));
return ret;
}

Expand All @@ -541,7 +571,6 @@ static int balance_node_right(struct ctree_root *root,
int src_nritems;
int dst_nritems;
int ret = 0;
int wret;

src_nritems = src->header.nritems;
dst_nritems = dst->header.nritems;
Expand Down Expand Up @@ -569,13 +598,8 @@ static int balance_node_right(struct ctree_root *root,
src->header.nritems -= push_items;
dst->header.nritems += push_items;

wret = dirty_tree_block(root, src_buf);
if (wret < 0)
ret = wret;

wret = dirty_tree_block(root, dst_buf);
if (wret < 0)
ret = wret;
BUG_ON(list_empty(&src_buf->dirty));
BUG_ON(list_empty(&dst_buf->dirty));
return ret;
}

Expand Down Expand Up @@ -615,7 +639,6 @@ static int insert_new_root(struct ctree_root *root,
tree_block_release(root, root->node);
root->node = t;
t->count++;
dirty_tree_block(root, t);
path->nodes[level] = t;
path->slots[level] = 0;
return 0;
Expand Down Expand Up @@ -655,7 +678,7 @@ static int insert_ptr(struct ctree_root *root,
lower->header.nritems++;
if (lower->keys[1].objectid == 0)
BUG();
dirty_tree_block(root, path->nodes[level]);
BUG_ON(list_empty(&path->nodes[level]->dirty));
return 0;
}

Expand Down Expand Up @@ -701,12 +724,7 @@ static int split_node(struct ctree_root *root, struct ctree_path *path,
c->header.nritems = mid;
ret = 0;

wret = dirty_tree_block(root, t);
if (wret)
ret = wret;
wret = dirty_tree_block(root, split_buffer);
if (wret)
ret = wret;
BUG_ON(list_empty(&t->dirty));
wret = insert_ptr(root, path, split->keys, split_buffer->blocknr,
path->slots[level + 1] + 1, level + 1);
if (wret)
Expand Down Expand Up @@ -778,6 +796,15 @@ static int push_leaf_right(struct ctree_root *root, struct ctree_path *path,
tree_block_release(root, right_buf);
return 1;
}
/* cow and double check */
btrfs_cow_block(root, right_buf, upper, slot + 1, &right_buf);
right = &right_buf->leaf;
free_space = leaf_free_space(right);
if (free_space < data_size + sizeof(struct item)) {
tree_block_release(root, right_buf);
return 1;
}

for (i = left->header.nritems - 1; i >= 0; i--) {
item = left->items + i;
if (path->slots[0] == i)
Expand Down Expand Up @@ -818,11 +845,12 @@ static int push_leaf_right(struct ctree_root *root, struct ctree_path *path,
}
left->header.nritems -= push_items;

dirty_tree_block(root, left_buf);
dirty_tree_block(root, right_buf);
BUG_ON(list_empty(&left_buf->dirty));
BUG_ON(list_empty(&right_buf->dirty));
memcpy(upper->node.keys + slot + 1,
&right->items[0].key, sizeof(struct key));
dirty_tree_block(root, upper);
BUG_ON(list_empty(&upper->dirty));

/* then fixup the leaf pointer in the path */
if (path->slots[0] >= left->header.nritems) {
path->slots[0] -= left->header.nritems;
Expand Down Expand Up @@ -869,6 +897,16 @@ static int push_leaf_left(struct ctree_root *root, struct ctree_path *path,
tree_block_release(root, t);
return 1;
}

/* cow and double check */
btrfs_cow_block(root, t, path->nodes[1], slot - 1, &t);
left = &t->leaf;
free_space = leaf_free_space(left);
if (free_space < data_size + sizeof(struct item)) {
tree_block_release(root, t);
return 1;
}

for (i = 0; i < right->header.nritems; i++) {
item = right->items + i;
if (path->slots[0] == i)
Expand Down Expand Up @@ -912,12 +950,8 @@ static int push_leaf_left(struct ctree_root *root, struct ctree_path *path,
push_space = right->items[i].offset;
}

wret = dirty_tree_block(root, t);
if (wret)
ret = wret;
wret = dirty_tree_block(root, right_buf);
if (wret)
ret = wret;
BUG_ON(list_empty(&t->dirty));
BUG_ON(list_empty(&right_buf->dirty));

wret = fixup_low_keys(root, path, &right->items[0].key, 1);
if (wret)
Expand Down Expand Up @@ -968,6 +1002,7 @@ static int split_leaf(struct ctree_root *root, struct ctree_path *path,
if (wret < 0)
return wret;
}

l_buf = path->nodes[0];
l = &l_buf->leaf;

Expand Down Expand Up @@ -1022,13 +1057,8 @@ static int split_leaf(struct ctree_root *root, struct ctree_path *path,
right_buffer->blocknr, path->slots[1] + 1, 1);
if (wret)
ret = wret;
wret = dirty_tree_block(root, right_buffer);
if (wret)
ret = wret;
wret = dirty_tree_block(root, l_buf);
if (wret)
ret = wret;

BUG_ON(list_empty(&right_buffer->dirty));
BUG_ON(list_empty(&l_buf->dirty));
BUG_ON(path->slots[0] != slot);
if (mid <= slot) {
tree_block_release(root, path->nodes[0]);
Expand All @@ -1049,7 +1079,6 @@ int insert_item(struct ctree_root *root, struct key *key,
void *data, int data_size)
{
int ret = 0;
int wret;
int slot;
int slot_orig;
struct leaf *leaf;
Expand All @@ -1062,7 +1091,7 @@ int insert_item(struct ctree_root *root, struct key *key,
if (!root->node)
BUG();
init_path(&path);
ret = search_slot(root, key, &path, data_size);
ret = search_slot(root, key, &path, data_size, 1);
if (ret == 0) {
release_path(root, &path);
return -EEXIST;
Expand Down Expand Up @@ -1114,10 +1143,7 @@ int insert_item(struct ctree_root *root, struct key *key,
if (slot == 0)
ret = fixup_low_keys(root, &path, key, 1);

wret = dirty_tree_block(root, leaf_buf);
if (wret)
ret = wret;

BUG_ON(list_empty(&leaf_buf->dirty));
if (leaf_free_space(leaf) < 0)
BUG();
check_leaf(&path, 0);
Expand Down Expand Up @@ -1162,9 +1188,7 @@ static int del_ptr(struct ctree_root *root, struct ctree_path *path, int level,
if (wret)
ret = wret;
}
wret = dirty_tree_block(root, parent);
if (wret)
ret = wret;
BUG_ON(list_empty(&parent->dirty));
return ret;
}

Expand Down Expand Up @@ -1205,7 +1229,7 @@ int del_item(struct ctree_root *root, struct ctree_path *path)
if (leaf->header.nritems == 0) {
if (leaf_buf == root->node) {
leaf->header.flags = node_level(0);
dirty_tree_block(root, leaf_buf);
BUG_ON(list_empty(&leaf_buf->dirty));
} else {
clean_tree_block(root, leaf_buf);
wret = del_ptr(root, path, 1, path->slots[1]);
Expand All @@ -1223,9 +1247,7 @@ int del_item(struct ctree_root *root, struct ctree_path *path)
if (wret)
ret = wret;
}
wret = dirty_tree_block(root, leaf_buf);
if (wret)
ret = wret;
BUG_ON(list_empty(&leaf_buf->dirty));

/* delete the leaf if it is mostly empty */
if (used < LEAF_DATA_SIZE / 3) {
Expand Down Expand Up @@ -1304,3 +1326,4 @@ int next_leaf(struct ctree_root *root, struct ctree_path *path)
return 0;
}


3 changes: 2 additions & 1 deletion fs/btrfs/ctree.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -142,8 +142,9 @@ struct ctree_path {
};

struct tree_buffer *alloc_free_block(struct ctree_root *root);
int btrfs_inc_ref(struct ctree_root *root, struct tree_buffer *buf);
int free_extent(struct ctree_root *root, u64 blocknr, u64 num_blocks);
int search_slot(struct ctree_root *root, struct key *key, struct ctree_path *p, int ins_len);
int search_slot(struct ctree_root *root, struct key *key, struct ctree_path *p, int ins_len, int cow);
void release_path(struct ctree_root *root, struct ctree_path *p);
void init_path(struct ctree_path *p);
int del_item(struct ctree_root *root, struct ctree_path *path);
Expand Down
2 changes: 2 additions & 0 deletions fs/btrfs/disk-io.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -260,6 +260,8 @@ void tree_block_release(struct ctree_root *root, struct tree_buffer *buf)
if (buf->count < 0)
BUG();
if (buf->count == 0) {
BUG_ON(!list_empty(&buf->cache));
BUG_ON(!list_empty(&buf->dirty));
if (!radix_tree_lookup(&root->cache_radix, buf->blocknr))
BUG();
radix_tree_delete(&root->cache_radix, buf->blocknr);
Expand Down
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