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Btrfs: Replace the big fs_mutex with a collection of other locks

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Extent alloctions are still protected by a large alloc_mutex.
Objectid allocations are covered by a objectid mutex
Other btree operations are protected by a lock on individual btree nodes

Signed-off-by: Chris Mason <chris.mason@oracle.com>
This commit is contained in:
Chris Mason
2008-06-25 16:01:30 -04:00
parent 925baeddc5
commit a213501153
12 changed files with 101 additions and 165 deletions
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40
fs/btrfs/ctree.c
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@@ -63,6 +63,9 @@ void btrfs_free_path(struct btrfs_path *p)
void btrfs_release_path(struct btrfs_root *root, struct btrfs_path *p)
{
int i;
int skip = p->skip_locking;
int keep = p->keep_locks;
for (i = 0; i < BTRFS_MAX_LEVEL; i++) {
if (!p->nodes[i])
continue;
@@ -73,6 +76,8 @@ void btrfs_release_path(struct btrfs_root *root, struct btrfs_path *p)
free_extent_buffer(p->nodes[i]);
}
memset(p, 0, sizeof(*p));
p->skip_locking = skip;
p->keep_locks = keep;
}
struct extent_buffer *btrfs_root_node(struct btrfs_root *root)
@@ -1202,13 +1207,19 @@ static void unlock_up(struct btrfs_path *path, int level, int lowest_unlock)
u32 nritems;
t = path->nodes[i];
nritems = btrfs_header_nritems(t);
if (path->slots[i] >= nritems - 1) {
if (nritems < 2 || path->slots[i] >= nritems - 2) {
if (path->keep_locks) {
//printk("path %p skip level now %d\n", path, skip_level);
}
skip_level = i + 1;
continue;
}
}
t = path->nodes[i];
if (i >= lowest_unlock && i > skip_level && path->locks[i]) {
if (path->keep_locks) {
//printk("path %p unlocking level %d slot %d nritems %d skip_level %d\n", path, i, path->slots[i], btrfs_header_nritems(t), skip_level);
}
btrfs_tree_unlock(t);
path->locks[i] = 0;
}
@@ -1243,7 +1254,6 @@ int btrfs_search_slot(struct btrfs_trans_handle *trans, struct btrfs_root
lowest_level = p->lowest_level;
WARN_ON(lowest_level && ins_len);
WARN_ON(p->nodes[0] != NULL);
// WARN_ON(!mutex_is_locked(&root->fs_info->fs_mutex));
WARN_ON(root == root->fs_info->extent_root &&
!mutex_is_locked(&root->fs_info->alloc_mutex));
WARN_ON(root == root->fs_info->chunk_root &&
@@ -1321,7 +1331,7 @@ again:
b = read_node_slot(root, b, slot);
if (!p->skip_locking)
btrfs_tree_lock(b);
unlock_up(p, level, lowest_unlock);
unlock_up(p, level + 1, lowest_unlock);
} else {
p->slots[level] = slot;
if (ins_len > 0 && btrfs_leaf_free_space(root, b) <
@@ -1804,6 +1814,8 @@ static int push_leaf_right(struct btrfs_trans_handle *trans, struct btrfs_root
if (slot >= btrfs_header_nritems(upper) - 1)
return 1;
WARN_ON(!btrfs_tree_locked(path->nodes[1]));
right = read_node_slot(root, upper, slot + 1);
btrfs_tree_lock(right);
free_space = btrfs_leaf_free_space(root, right);
@@ -1981,6 +1993,8 @@ static int push_leaf_left(struct btrfs_trans_handle *trans, struct btrfs_root
return 1;
}
WARN_ON(!btrfs_tree_locked(path->nodes[1]));
left = read_node_slot(root, path->nodes[1], slot - 1);
btrfs_tree_lock(left);
free_space = btrfs_leaf_free_space(root, left);
@@ -2957,15 +2971,16 @@ int btrfs_next_leaf(struct btrfs_root *root, struct btrfs_path *path)
btrfs_item_key_to_cpu(path->nodes[0], &key, nritems - 1);
path->keep_locks = 1;
btrfs_release_path(root, path);
path->keep_locks = 1;
ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
path->keep_locks = 0;
if (ret < 0)
return ret;
if (path->slots[0] < nritems - 1) {
nritems = btrfs_header_nritems(path->nodes[0]);
if (nritems > 0 && path->slots[0] < nritems - 1) {
goto done;
}
@@ -2992,8 +3007,17 @@ int btrfs_next_leaf(struct btrfs_root *root, struct btrfs_path *path)
reada_for_search(root, path, level, slot, 0);
next = read_node_slot(root, c, slot);
if (!path->skip_locking)
if (!path->skip_locking) {
if (!btrfs_tree_locked(c)) {
int i;
WARN_ON(1);
printk("path %p no lock on level %d\n", path, level);
for (i = 0; i < BTRFS_MAX_LEVEL; i++) {
printk("path %p level %d slot %d nritems %d\n", path, i, path->slots[i], btrfs_header_nritems(path->nodes[i]));
}
}
btrfs_tree_lock(next);
}
break;
}
path->slots[level] = slot;
@@ -3011,8 +3035,10 @@ int btrfs_next_leaf(struct btrfs_root *root, struct btrfs_path *path)
if (level == 1 && path->locks[1] && path->reada)
reada_for_search(root, path, level, slot, 0);
next = read_node_slot(root, next, 0);
if (!path->skip_locking)
if (!path->skip_locking) {
WARN_ON(!btrfs_tree_locked(path->nodes[level]));
btrfs_tree_lock(next);
}
}
done:
unlock_up(path, 0, 1);