linux/fs/btrfs/extent-tree.c

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#include <linux/module.h>
#include <linux/radix-tree.h>
#include "ctree.h"
#include "disk-io.h"
#include "print-tree.h"
#include "transaction.h"
static int find_free_extent(struct btrfs_trans_handle *trans, struct btrfs_root
*orig_root, u64 num_blocks, u64 search_start, u64
search_end, struct btrfs_key *ins);
static int finish_current_insert(struct btrfs_trans_handle *trans, struct
btrfs_root *extent_root);
static int del_pending_extents(struct btrfs_trans_handle *trans, struct
btrfs_root *extent_root);
/*
* pending extents are blocks that we're trying to allocate in the extent
* map while trying to grow the map because of other allocations. To avoid
* recursing, they are tagged in the radix tree and cleaned up after
* other allocations are done. The pending tag is also used in the same
* manner for deletes.
*/
#define CTREE_EXTENT_PENDING_DEL 0
#define CTREE_EXTENT_PINNED 1
static int inc_block_ref(struct btrfs_trans_handle *trans, struct btrfs_root
*root, u64 blocknr)
{
struct btrfs_path path;
int ret;
struct btrfs_key key;
struct btrfs_leaf *l;
struct btrfs_extent_item *item;
struct btrfs_key ins;
u32 refs;
find_free_extent(trans, root->fs_info->extent_root, 0, 0, (u64)-1,
&ins);
btrfs_init_path(&path);
key.objectid = blocknr;
key.flags = 0;
btrfs_set_key_type(&key, BTRFS_EXTENT_ITEM_KEY);
key.offset = 1;
ret = btrfs_search_slot(trans, root->fs_info->extent_root, &key, &path,
0, 1);
if (ret != 0)
BUG();
BUG_ON(ret != 0);
l = btrfs_buffer_leaf(path.nodes[0]);
item = btrfs_item_ptr(l, path.slots[0], struct btrfs_extent_item);
refs = btrfs_extent_refs(item);
btrfs_set_extent_refs(item, refs + 1);
mark_buffer_dirty(path.nodes[0]);
btrfs_release_path(root->fs_info->extent_root, &path);
finish_current_insert(trans, root->fs_info->extent_root);
del_pending_extents(trans, root->fs_info->extent_root);
return 0;
}
static int lookup_block_ref(struct btrfs_trans_handle *trans, struct btrfs_root
*root, u64 blocknr, u32 *refs)
{
struct btrfs_path path;
int ret;
struct btrfs_key key;
struct btrfs_leaf *l;
struct btrfs_extent_item *item;
btrfs_init_path(&path);
key.objectid = blocknr;
key.offset = 1;
key.flags = 0;
btrfs_set_key_type(&key, BTRFS_EXTENT_ITEM_KEY);
ret = btrfs_search_slot(trans, root->fs_info->extent_root, &key, &path,
0, 0);
if (ret != 0)
BUG();
l = btrfs_buffer_leaf(path.nodes[0]);
item = btrfs_item_ptr(l, path.slots[0], struct btrfs_extent_item);
*refs = btrfs_extent_refs(item);
btrfs_release_path(root->fs_info->extent_root, &path);
return 0;
}
int btrfs_inc_ref(struct btrfs_trans_handle *trans, struct btrfs_root *root,
struct buffer_head *buf)
{
u64 blocknr;
struct btrfs_node *buf_node;
int i;
if (!root->ref_cows)
return 0;
buf_node = btrfs_buffer_node(buf);
if (btrfs_is_leaf(buf_node))
return 0;
for (i = 0; i < btrfs_header_nritems(&buf_node->header); i++) {
blocknr = btrfs_node_blockptr(buf_node, i);
inc_block_ref(trans, root, blocknr);
}
return 0;
}
int btrfs_finish_extent_commit(struct btrfs_trans_handle *trans, struct
btrfs_root *root)
{
struct buffer_head *gang[8];
u64 first = 0;
int ret;
int i;
while(1) {
ret = radix_tree_gang_lookup_tag(&root->fs_info->pinned_radix,
(void **)gang, 0,
ARRAY_SIZE(gang),
CTREE_EXTENT_PINNED);
if (!ret)
break;
if (!first)
first = gang[0]->b_blocknr;
for (i = 0; i < ret; i++) {
radix_tree_delete(&root->fs_info->pinned_radix,
gang[i]->b_blocknr);
brelse(gang[i]);
}
}
if (root->fs_info->last_insert.objectid > first)
root->fs_info->last_insert.objectid = first;
root->fs_info->last_insert.offset = 0;
return 0;
}
static int finish_current_insert(struct btrfs_trans_handle *trans, struct
btrfs_root *extent_root)
{
struct btrfs_key ins;
struct btrfs_extent_item extent_item;
int i;
int ret;
u64 super_blocks_used;
struct btrfs_fs_info *info = extent_root->fs_info;
btrfs_set_extent_refs(&extent_item, 1);
btrfs_set_extent_owner(&extent_item,
btrfs_header_parentid(btrfs_buffer_header(extent_root->node)));
ins.offset = 1;
ins.flags = 0;
btrfs_set_key_type(&ins, BTRFS_EXTENT_ITEM_KEY);
for (i = 0; i < extent_root->fs_info->current_insert.flags; i++) {
ins.objectid = extent_root->fs_info->current_insert.objectid +
i;
super_blocks_used = btrfs_super_blocks_used(info->disk_super);
btrfs_set_super_blocks_used(info->disk_super,
super_blocks_used + 1);
ret = btrfs_insert_item(trans, extent_root, &ins, &extent_item,
sizeof(extent_item));
BUG_ON(ret);
}
extent_root->fs_info->current_insert.offset = 0;
return 0;
}
static int pin_down_block(struct btrfs_root *root, u64 blocknr, int tag)
{
int err;
struct buffer_head *bh = sb_getblk(root->fs_info->sb, blocknr);
BUG_ON(!bh);
err = radix_tree_insert(&root->fs_info->pinned_radix,
blocknr, bh);
BUG_ON(err);
if (err)
return err;
radix_tree_tag_set(&root->fs_info->pinned_radix, blocknr,
tag);
return 0;
}
/*
* remove an extent from the root, returns 0 on success
*/
static int __free_extent(struct btrfs_trans_handle *trans, struct btrfs_root
*root, u64 blocknr, u64 num_blocks)
{
struct btrfs_path path;
struct btrfs_key key;
struct btrfs_fs_info *info = root->fs_info;
struct btrfs_root *extent_root = info->extent_root;
int ret;
struct btrfs_extent_item *ei;
struct btrfs_key ins;
u32 refs;
key.objectid = blocknr;
key.flags = 0;
btrfs_set_key_type(&key, BTRFS_EXTENT_ITEM_KEY);
key.offset = num_blocks;
find_free_extent(trans, root, 0, 0, (u64)-1, &ins);
btrfs_init_path(&path);
ret = btrfs_search_slot(trans, extent_root, &key, &path, -1, 1);
if (ret) {
printk("failed to find %Lu\n", key.objectid);
btrfs_print_tree(extent_root, extent_root->node);
printk("failed to find %Lu\n", key.objectid);
BUG();
}
ei = btrfs_item_ptr(btrfs_buffer_leaf(path.nodes[0]), path.slots[0],
struct btrfs_extent_item);
BUG_ON(ei->refs == 0);
refs = btrfs_extent_refs(ei) - 1;
btrfs_set_extent_refs(ei, refs);
if (refs == 0) {
u64 super_blocks_used;
super_blocks_used = btrfs_super_blocks_used(info->disk_super);
btrfs_set_super_blocks_used(info->disk_super,
super_blocks_used - num_blocks);
ret = btrfs_del_item(trans, extent_root, &path);
if (extent_root->fs_info->last_insert.objectid >
blocknr)
extent_root->fs_info->last_insert.objectid = blocknr;
if (ret)
BUG();
}
mark_buffer_dirty(path.nodes[0]);
btrfs_release_path(extent_root, &path);
finish_current_insert(trans, extent_root);
return ret;
}
/*
* find all the blocks marked as pending in the radix tree and remove
* them from the extent map
*/
static int del_pending_extents(struct btrfs_trans_handle *trans, struct
btrfs_root *extent_root)
{
int ret;
int wret;
int err = 0;
struct buffer_head *gang[4];
int i;
struct radix_tree_root *radix = &extent_root->fs_info->pinned_radix;
while(1) {
ret = radix_tree_gang_lookup_tag(
&extent_root->fs_info->pinned_radix,
(void **)gang, 0,
ARRAY_SIZE(gang),
CTREE_EXTENT_PENDING_DEL);
if (!ret)
break;
for (i = 0; i < ret; i++) {
radix_tree_tag_set(radix, gang[i]->b_blocknr,
CTREE_EXTENT_PINNED);
radix_tree_tag_clear(radix, gang[i]->b_blocknr,
CTREE_EXTENT_PENDING_DEL);
wret = __free_extent(trans, extent_root,
gang[i]->b_blocknr, 1);
if (wret)
err = wret;
}
}
return err;
}
/*
* remove an extent from the root, returns 0 on success
*/
int btrfs_free_extent(struct btrfs_trans_handle *trans, struct btrfs_root
*root, u64 blocknr, u64 num_blocks, int pin)
{
struct btrfs_root *extent_root = root->fs_info->extent_root;
struct buffer_head *t;
int pending_ret;
int ret;
if (root == extent_root) {
t = find_tree_block(root, blocknr);
pin_down_block(root, blocknr, CTREE_EXTENT_PENDING_DEL);
return 0;
}
if (pin) {
ret = pin_down_block(root, blocknr, CTREE_EXTENT_PINNED);
BUG_ON(ret);
}
ret = __free_extent(trans, root, blocknr, num_blocks);
pending_ret = del_pending_extents(trans, root->fs_info->extent_root);
return ret ? ret : pending_ret;
}
/*
* walks the btree of allocated extents and find a hole of a given size.
* The key ins is changed to record the hole:
* ins->objectid == block start
* ins->flags = BTRFS_EXTENT_ITEM_KEY
* ins->offset == number of blocks
* Any available blocks before search_start are skipped.
*/
static int find_free_extent(struct btrfs_trans_handle *trans, struct btrfs_root
*orig_root, u64 num_blocks, u64 search_start, u64
search_end, struct btrfs_key *ins)
{
struct btrfs_path path;
struct btrfs_key key;
int ret;
u64 hole_size = 0;
int slot = 0;
u64 last_block = 0;
u64 test_block;
int start_found;
struct btrfs_leaf *l;
struct btrfs_root * root = orig_root->fs_info->extent_root;
int total_needed = num_blocks;
int level;
level = btrfs_header_level(btrfs_buffer_header(root->node));
total_needed += (level + 1) * 3;
if (root->fs_info->last_insert.objectid > search_start)
search_start = root->fs_info->last_insert.objectid;
ins->flags = 0;
btrfs_set_key_type(ins, BTRFS_EXTENT_ITEM_KEY);
check_failed:
btrfs_init_path(&path);
ins->objectid = search_start;
ins->offset = 0;
start_found = 0;
ret = btrfs_search_slot(trans, root, ins, &path, 0, 0);
if (ret < 0)
goto error;
if (path.slots[0] > 0)
path.slots[0]--;
while (1) {
l = btrfs_buffer_leaf(path.nodes[0]);
slot = path.slots[0];
if (slot >= btrfs_header_nritems(&l->header)) {
ret = btrfs_next_leaf(root, &path);
if (ret == 0)
continue;
if (ret < 0)
goto error;
if (!start_found) {
ins->objectid = search_start;
ins->offset = (u64)-1;
start_found = 1;
goto check_pending;
}
ins->objectid = last_block > search_start ?
last_block : search_start;
ins->offset = (u64)-1;
goto check_pending;
}
btrfs_disk_key_to_cpu(&key, &l->items[slot].key);
if (key.objectid >= search_start) {
if (start_found) {
if (last_block < search_start)
last_block = search_start;
hole_size = key.objectid - last_block;
if (hole_size > total_needed) {
ins->objectid = last_block;
ins->offset = hole_size;
goto check_pending;
}
}
}
start_found = 1;
last_block = key.objectid + key.offset;
path.slots[0]++;
}
// FIXME -ENOSPC
check_pending:
/* we have to make sure we didn't find an extent that has already
* been allocated by the map tree or the original allocation
*/
btrfs_release_path(root, &path);
BUG_ON(ins->objectid < search_start);
for (test_block = ins->objectid;
test_block < ins->objectid + total_needed; test_block++) {
if (radix_tree_lookup(&root->fs_info->pinned_radix,
test_block)) {
search_start = test_block + 1;
goto check_failed;
}
}
BUG_ON(root->fs_info->current_insert.offset);
root->fs_info->current_insert.offset = total_needed - num_blocks;
root->fs_info->current_insert.objectid = ins->objectid + num_blocks;
root->fs_info->current_insert.flags = 0;
root->fs_info->last_insert.objectid = ins->objectid;
ins->offset = num_blocks;
return 0;
error:
btrfs_release_path(root, &path);
return ret;
}
/*
* finds a free extent and does all the dirty work required for allocation
* returns the key for the extent through ins, and a tree buffer for
* the first block of the extent through buf.
*
* returns 0 if everything worked, non-zero otherwise.
*/
static int alloc_extent(struct btrfs_trans_handle *trans, struct btrfs_root
*root, u64 num_blocks, u64 search_start, u64
search_end, u64 owner, struct btrfs_key *ins)
{
int ret;
int pending_ret;
u64 super_blocks_used;
struct btrfs_fs_info *info = root->fs_info;
struct btrfs_root *extent_root = info->extent_root;
struct btrfs_extent_item extent_item;
btrfs_set_extent_refs(&extent_item, 1);
btrfs_set_extent_owner(&extent_item, owner);
if (root == extent_root) {
BUG_ON(extent_root->fs_info->current_insert.offset == 0);
BUG_ON(num_blocks != 1);
BUG_ON(extent_root->fs_info->current_insert.flags ==
extent_root->fs_info->current_insert.offset);
ins->offset = 1;
ins->objectid = extent_root->fs_info->current_insert.objectid +
extent_root->fs_info->current_insert.flags++;
return 0;
}
ret = find_free_extent(trans, root, num_blocks, search_start,
search_end, ins);
if (ret)
return ret;
super_blocks_used = btrfs_super_blocks_used(info->disk_super);
btrfs_set_super_blocks_used(info->disk_super, super_blocks_used +
num_blocks);
ret = btrfs_insert_item(trans, extent_root, ins, &extent_item,
sizeof(extent_item));
finish_current_insert(trans, extent_root);
pending_ret = del_pending_extents(trans, extent_root);
if (ret)
return ret;
if (pending_ret)
return pending_ret;
return 0;
}
/*
* helper function to allocate a block for a given tree
* returns the tree buffer or NULL.
*/
struct buffer_head *btrfs_alloc_free_block(struct btrfs_trans_handle *trans,
struct btrfs_root *root)
{
struct btrfs_key ins;
int ret;
struct buffer_head *buf;
ret = alloc_extent(trans, root, 1, 0, (unsigned long)-1,
btrfs_header_parentid(btrfs_buffer_header(root->node)), &ins);
if (ret) {
BUG();
return NULL;
}
buf = find_tree_block(root, ins.objectid);
dirty_tree_block(trans, root, buf);
return buf;
}
/*
* helper function for drop_snapshot, this walks down the tree dropping ref
* counts as it goes.
*/
static int walk_down_tree(struct btrfs_trans_handle *trans, struct btrfs_root
*root, struct btrfs_path *path, int *level)
{
struct buffer_head *next;
struct buffer_head *cur;
u64 blocknr;
int ret;
u32 refs;
ret = lookup_block_ref(trans, root, path->nodes[*level]->b_blocknr,
&refs);
BUG_ON(ret);
if (refs > 1)
goto out;
/*
* walk down to the last node level and free all the leaves
*/
while(*level > 0) {
cur = path->nodes[*level];
if (path->slots[*level] >=
btrfs_header_nritems(btrfs_buffer_header(cur)))
break;
blocknr = btrfs_node_blockptr(btrfs_buffer_node(cur),
path->slots[*level]);
ret = lookup_block_ref(trans, root, blocknr, &refs);
if (refs != 1 || *level == 1) {
path->slots[*level]++;
ret = btrfs_free_extent(trans, root, blocknr, 1, 1);
BUG_ON(ret);
continue;
}
BUG_ON(ret);
next = read_tree_block(root, blocknr);
if (path->nodes[*level-1])
btrfs_block_release(root, path->nodes[*level-1]);
path->nodes[*level-1] = next;
*level = btrfs_header_level(btrfs_buffer_header(next));
path->slots[*level] = 0;
}
out:
ret = btrfs_free_extent(trans, root, path->nodes[*level]->b_blocknr,
1, 1);
btrfs_block_release(root, path->nodes[*level]);
path->nodes[*level] = NULL;
*level += 1;
BUG_ON(ret);
return 0;
}
/*
* helper for dropping snapshots. This walks back up the tree in the path
* to find the first node higher up where we haven't yet gone through
* all the slots
*/
static int walk_up_tree(struct btrfs_trans_handle *trans, struct btrfs_root
*root, struct btrfs_path *path, int *level)
{
int i;
int slot;
int ret;
for(i = *level; i < BTRFS_MAX_LEVEL - 1 && path->nodes[i]; i++) {
slot = path->slots[i];
if (slot < btrfs_header_nritems(
btrfs_buffer_header(path->nodes[i])) - 1) {
path->slots[i]++;
*level = i;
return 0;
} else {
ret = btrfs_free_extent(trans, root,
path->nodes[*level]->b_blocknr,
1, 1);
btrfs_block_release(root, path->nodes[*level]);
path->nodes[*level] = NULL;
*level = i + 1;
BUG_ON(ret);
}
}
return 1;
}
/*
* drop the reference count on the tree rooted at 'snap'. This traverses
* the tree freeing any blocks that have a ref count of zero after being
* decremented.
*/
int btrfs_drop_snapshot(struct btrfs_trans_handle *trans, struct btrfs_root
*root, struct buffer_head *snap)
{
int ret = 0;
int wret;
int level;
struct btrfs_path path;
int i;
int orig_level;
btrfs_init_path(&path);
level = btrfs_header_level(btrfs_buffer_header(snap));
orig_level = level;
path.nodes[level] = snap;
path.slots[level] = 0;
while(1) {
wret = walk_down_tree(trans, root, &path, &level);
if (wret > 0)
break;
if (wret < 0)
ret = wret;
wret = walk_up_tree(trans, root, &path, &level);
if (wret > 0)
break;
if (wret < 0)
ret = wret;
}
for (i = 0; i <= orig_level; i++) {
if (path.nodes[i]) {
btrfs_block_release(root, path.nodes[i]);
}
}
return ret;
}