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Btrfs: Add btree locking to the tree defragmentation code 

The online btree defragger is simplified and rewritten to use
standard btree searches instead of a walk up / down mechanism.

Signed-off-by: Chris Mason <chris.mason@oracle.com>
This commit is contained in:
Chris Mason 2008-06-25 16:01:31 -04:00
parent a74a4b97b6
commit e7a84565bc
4 changed files with 93 additions and 201 deletions
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46
fs/btrfs/ctree.c
View File

@ -354,7 +354,6 @@ int btrfs_realloc_node(struct btrfs_trans_handle *trans,
struct btrfs_key *progress)
{
struct extent_buffer *cur;
struct extent_buffer *tmp;
u64 blocknr;
u64 gen;
u64 search_start = *last_ret;
@ -370,9 +369,6 @@ int btrfs_realloc_node(struct btrfs_trans_handle *trans,
int progress_passed = 0;
struct btrfs_disk_key disk_key;
/* FIXME this code needs locking */
return 0;
parent_level = btrfs_header_level(parent);
if (cache_only && parent_level != 1)
return 0;
@ -454,20 +450,23 @@ int btrfs_realloc_node(struct btrfs_trans_handle *trans,
if (search_start == 0)
search_start = last_block;
btrfs_tree_lock(cur);
err = __btrfs_cow_block(trans, root, cur, parent, i,
&tmp, search_start,
&cur, search_start,
min(16 * blocksize,
(end_slot - i) * blocksize));
if (err) {
btrfs_tree_unlock(cur);
free_extent_buffer(cur);
break;
}
search_start = tmp->start;
last_block = tmp->start;
search_start = cur->start;
last_block = cur->start;
*last_ret = search_start;
if (parent_level == 1)
btrfs_clear_buffer_defrag(tmp);
free_extent_buffer(tmp);
btrfs_clear_buffer_defrag(cur);
btrfs_tree_unlock(cur);
free_extent_buffer(cur);
}
if (parent->map_token) {
unmap_extent_buffer(parent, parent->map_token,
@ -2970,6 +2969,35 @@ int btrfs_prev_leaf(struct btrfs_root *root, struct btrfs_path *path)
return 1;
}
int btrfs_find_next_key(struct btrfs_root *root, struct btrfs_path *path,
struct btrfs_key *key, int lowest_level)
{
int level = lowest_level;
int slot;
struct extent_buffer *c;
while(level < BTRFS_MAX_LEVEL) {
if (!path->nodes[level])
return 1;
slot = path->slots[level] + 1;
c = path->nodes[level];
if (slot >= btrfs_header_nritems(c)) {
level++;
if (level == BTRFS_MAX_LEVEL) {
return 1;
}
continue;
}
if (level == 0)
btrfs_item_key_to_cpu(c, key, slot);
else
btrfs_node_key_to_cpu(c, key, slot);
return 0;
}
return 1;
}
/*
* search the tree again to find a leaf with greater keys
* returns 0 if it found something or 1 if there are no greater leaves.

2
fs/btrfs/ctree.h
View File

@ -1411,6 +1411,8 @@ int btrfs_previous_item(struct btrfs_root *root,
struct extent_buffer *btrfs_root_node(struct btrfs_root *root);
struct extent_buffer *btrfs_lock_root_node(struct btrfs_root *root);
int btrfs_find_next_key(struct btrfs_root *root, struct btrfs_path *path,
struct btrfs_key *key, int lowest_level);
int btrfs_cow_block(struct btrfs_trans_handle *trans,
struct btrfs_root *root, struct extent_buffer *buf,

7
fs/btrfs/extent-tree.c
View File

@ -2201,6 +2201,7 @@ int drop_snap_lookup_refcount(struct btrfs_root *root, u64 start, u64 len,
{
mutex_unlock(&root->fs_info->alloc_mutex);
lookup_extent_ref(NULL, root, start, len, refs);
cond_resched();
mutex_lock(&root->fs_info->alloc_mutex);
return lookup_extent_ref(NULL, root, start, len, refs);
}
@ -2280,6 +2281,7 @@ static int noinline walk_down_tree(struct btrfs_trans_handle *trans,
next = read_tree_block(root, bytenr, blocksize,
ptr_gen);
cond_resched();
mutex_lock(&root->fs_info->alloc_mutex);
/* we've dropped the lock, double check */
@ -2329,6 +2331,7 @@ out:
*level += 1;
BUG_ON(ret);
mutex_unlock(&root->fs_info->alloc_mutex);
cond_resched();
return 0;
}
@ -2448,6 +2451,10 @@ int btrfs_drop_snapshot(struct btrfs_trans_handle *trans, struct btrfs_root
break;
if (wret < 0)
ret = wret;
if (trans->transaction->in_commit) {
ret = -EAGAIN;
break;
}
}
for (i = 0; i <= orig_level; i++) {
if (path->nodes[i]) {

239
fs/btrfs/tree-defrag.c
View File

@ -21,167 +21,26 @@
#include "disk-io.h"
#include "print-tree.h"
#include "transaction.h"
static void reada_defrag(struct btrfs_root *root,
struct extent_buffer *node)
{
int i;
u32 nritems;
u64 bytenr;
u64 gen;
u32 blocksize;
int ret;
blocksize = btrfs_level_size(root, btrfs_header_level(node) - 1);
nritems = btrfs_header_nritems(node);
for (i = 0; i < nritems; i++) {
bytenr = btrfs_node_blockptr(node, i);
gen = btrfs_node_ptr_generation(node, i);
ret = readahead_tree_block(root, bytenr, blocksize, gen);
if (ret)
break;
}
}
static int defrag_walk_down(struct btrfs_trans_handle *trans,
struct btrfs_root *root,
struct btrfs_path *path, int *level,
int cache_only, u64 *last_ret)
{
struct extent_buffer *next;
struct extent_buffer *cur;
u64 bytenr;
u64 ptr_gen;
int ret = 0;
int is_extent = 0;
WARN_ON(*level < 0);
WARN_ON(*level >= BTRFS_MAX_LEVEL);
if (root->fs_info->extent_root == root)
is_extent = 1;
if (*level == 1 && cache_only && path->nodes[1] &&
!btrfs_buffer_defrag(path->nodes[1])) {
goto out;
}
while(*level > 0) {
WARN_ON(*level < 0);
WARN_ON(*level >= BTRFS_MAX_LEVEL);
cur = path->nodes[*level];
if (!cache_only && *level > 1 && path->slots[*level] == 0)
reada_defrag(root, cur);
if (btrfs_header_level(cur) != *level)
WARN_ON(1);
if (path->slots[*level] >=
btrfs_header_nritems(cur))
break;
if (*level == 1) {
WARN_ON(btrfs_header_generation(path->nodes[*level]) !=
trans->transid);
ret = btrfs_realloc_node(trans, root,
path->nodes[*level],
path->slots[*level],
cache_only, last_ret,
&root->defrag_progress);
if (is_extent)
btrfs_extent_post_op(trans, root);
break;
}
bytenr = btrfs_node_blockptr(cur, path->slots[*level]);
ptr_gen = btrfs_node_ptr_generation(cur, path->slots[*level]);
if (cache_only) {
next = btrfs_find_tree_block(root, bytenr,
btrfs_level_size(root, *level - 1));
if (!next || !btrfs_buffer_uptodate(next, ptr_gen) ||
!btrfs_buffer_defrag(next)) {
free_extent_buffer(next);
path->slots[*level]++;
continue;
}
} else {
next = read_tree_block(root, bytenr,
btrfs_level_size(root, *level - 1),
ptr_gen);
}
ret = btrfs_cow_block(trans, root, next, path->nodes[*level],
path->slots[*level], &next);
BUG_ON(ret);
if (is_extent)
btrfs_extent_post_op(trans, root);
WARN_ON(*level <= 0);
if (path->nodes[*level-1])
free_extent_buffer(path->nodes[*level-1]);
path->nodes[*level-1] = next;
*level = btrfs_header_level(next);
path->slots[*level] = 0;
}
WARN_ON(*level < 0);
WARN_ON(*level >= BTRFS_MAX_LEVEL);
btrfs_clear_buffer_defrag(path->nodes[*level]);
out:
free_extent_buffer(path->nodes[*level]);
path->nodes[*level] = NULL;
*level += 1;
WARN_ON(ret && ret != -EAGAIN);
return ret;
}
static int defrag_walk_up(struct btrfs_trans_handle *trans,
struct btrfs_root *root,
struct btrfs_path *path, int *level,
int cache_only)
{
int i;
int slot;
struct extent_buffer *node;
for(i = *level; i < BTRFS_MAX_LEVEL - 1 && path->nodes[i]; i++) {
slot = path->slots[i];
if (slot < btrfs_header_nritems(path->nodes[i]) - 1) {
path->slots[i]++;
*level = i;
node = path->nodes[i];
WARN_ON(i == 0);
btrfs_node_key_to_cpu(node, &root->defrag_progress,
path->slots[i]);
root->defrag_level = i;
return 0;
} else {
btrfs_clear_buffer_defrag(path->nodes[*level]);
free_extent_buffer(path->nodes[*level]);
path->nodes[*level] = NULL;
*level = i + 1;
}
}
return 1;
}
#include "locking.h"
int btrfs_defrag_leaves(struct btrfs_trans_handle *trans,
struct btrfs_root *root, int cache_only)
{
struct btrfs_path *path = NULL;
struct extent_buffer *tmp;
struct btrfs_key key;
int ret = 0;
int wret;
int level;
int orig_level;
int i;
int is_extent = 0;
int next_key_ret = 0;
u64 last_ret = 0;
if (root->fs_info->extent_root == root)
if (root->fs_info->extent_root == root) {
mutex_lock(&root->fs_info->alloc_mutex);
is_extent = 1;
goto out;
}
if (root->ref_cows == 0 && !is_extent)
goto out;
@ -200,67 +59,63 @@ int btrfs_defrag_leaves(struct btrfs_trans_handle *trans,
goto out;
}
if (root->defrag_progress.objectid == 0) {
struct extent_buffer *root_node;
u32 nritems;
nritems = btrfs_header_nritems(root->node);
root_node = btrfs_lock_root_node(root);
nritems = btrfs_header_nritems(root_node);
root->defrag_max.objectid = 0;
/* from above we know this is not a leaf */
btrfs_node_key_to_cpu(root->node, &root->defrag_max,
btrfs_node_key_to_cpu(root_node, &root->defrag_max,
nritems - 1);
extent_buffer_get(root->node);
ret = btrfs_cow_block(trans, root, root->node, NULL, 0, &tmp);
BUG_ON(ret);
path->nodes[level] = root->node;
path->slots[level] = 0;
if (is_extent)
btrfs_extent_post_op(trans, root);
btrfs_tree_unlock(root_node);
free_extent_buffer(root_node);
memset(&key, 0, sizeof(key));
} else {
level = root->defrag_level;
path->lowest_level = level;
wret = btrfs_search_slot(trans, root, &root->defrag_progress,
path, 0, 1);
if (is_extent)
btrfs_extent_post_op(trans, root);
if (wret < 0) {
ret = wret;
goto out;
}
while(level > 0 && !path->nodes[level])
level--;
if (!path->nodes[level]) {
ret = 0;
goto out;
}
memcpy(&key, &root->defrag_progress, sizeof(key));
}
while(1) {
wret = defrag_walk_down(trans, root, path, &level, cache_only,
&last_ret);
if (wret > 0)
break;
if (wret < 0)
ret = wret;
path->lowest_level = 1;
path->keep_locks = 1;
wret = btrfs_search_slot(trans, root, &key, path, 0, 1);
wret = defrag_walk_up(trans, root, path, &level, cache_only);
if (wret > 0)
break;
if (wret < 0)
ret = wret;
else
ret = -EAGAIN;
break;
if (wret < 0) {
ret = wret;
goto out;
}
for (i = 0; i <= orig_level; i++) {
if (!path->nodes[1]) {
ret = 0;
goto out;
}
path->slots[1] = btrfs_header_nritems(path->nodes[1]);
next_key_ret = btrfs_find_next_key(root, path, &key, 1);
ret = btrfs_realloc_node(trans, root,
path->nodes[1], 0,
cache_only, &last_ret,
&root->defrag_progress);
WARN_ON(ret && ret != -EAGAIN);
if (next_key_ret == 0) {
memcpy(&root->defrag_progress, &key, sizeof(key));
ret = -EAGAIN;
}
for (i = 1; i < BTRFS_MAX_LEVEL; i++) {
if (path->locks[i]) {
btrfs_tree_unlock(path->nodes[i]);
path->locks[i] = 0;
}
if (path->nodes[i]) {
free_extent_buffer(path->nodes[i]);
path->nodes[i] = NULL;
}
}
if (is_extent)
btrfs_extent_post_op(trans, root);
out:
if (is_extent)
mutex_unlock(&root->fs_info->alloc_mutex);
if (path)
btrfs_free_path(path);
if (ret == -EAGAIN) {