Btrfs: Replace the big fs_mutex with a collection of other locks
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>
diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c
index 75625c6..dff4da0 100644
--- a/fs/btrfs/ctree.c
+++ b/fs/btrfs/ctree.c
@@ -63,6 +63,9 @@
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 @@
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 @@
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 @@
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 @@
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 @@
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 @@
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 @@
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 @@
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 @@
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);