btrfs: introduce BTRFS_NESTING_COW for cow'ing blocks
When we COW a block we are holding a lock on the original block, and
then we lock the new COW block. Because our lockdep maps are based on
root + level, this will make lockdep complain. We need a way to
indicate a subclass for locking the COW'ed block, so plumb through our
btrfs_lock_nesting from btrfs_cow_block down to the btrfs_init_buffer,
and then introduce BTRFS_NESTING_COW to be used for cow'ing blocks.
The reason I've added all this extra infrastructure is because there
will be need of different nesting classes in follow up patches.
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c
index 71e3fa3..48178fd 100644
--- a/fs/btrfs/ctree.c
+++ b/fs/btrfs/ctree.c
@@ -198,7 +198,7 @@ int btrfs_copy_root(struct btrfs_trans_handle *trans,
btrfs_node_key(buf, &disk_key, 0);
cow = btrfs_alloc_tree_block(trans, root, 0, new_root_objectid,
- &disk_key, level, buf->start, 0);
+ &disk_key, level, buf->start, 0, BTRFS_NESTING_NORMAL);
if (IS_ERR(cow))
return PTR_ERR(cow);
@@ -957,7 +957,8 @@ static struct extent_buffer *alloc_tree_block_no_bg_flush(
const struct btrfs_disk_key *disk_key,
int level,
u64 hint,
- u64 empty_size)
+ u64 empty_size,
+ enum btrfs_lock_nesting nest)
{
struct btrfs_fs_info *fs_info = root->fs_info;
struct extent_buffer *ret;
@@ -986,7 +987,7 @@ static struct extent_buffer *alloc_tree_block_no_bg_flush(
ret = btrfs_alloc_tree_block(trans, root, parent_start,
root->root_key.objectid, disk_key, level,
- hint, empty_size);
+ hint, empty_size, nest);
trans->can_flush_pending_bgs = true;
return ret;
@@ -1009,7 +1010,8 @@ static noinline int __btrfs_cow_block(struct btrfs_trans_handle *trans,
struct extent_buffer *buf,
struct extent_buffer *parent, int parent_slot,
struct extent_buffer **cow_ret,
- u64 search_start, u64 empty_size)
+ u64 search_start, u64 empty_size,
+ enum btrfs_lock_nesting nest)
{
struct btrfs_fs_info *fs_info = root->fs_info;
struct btrfs_disk_key disk_key;
@@ -1040,7 +1042,7 @@ static noinline int __btrfs_cow_block(struct btrfs_trans_handle *trans,
parent_start = parent->start;
cow = alloc_tree_block_no_bg_flush(trans, root, parent_start, &disk_key,
- level, search_start, empty_size);
+ level, search_start, empty_size, nest);
if (IS_ERR(cow))
return PTR_ERR(cow);
@@ -1446,7 +1448,8 @@ static inline int should_cow_block(struct btrfs_trans_handle *trans,
noinline int btrfs_cow_block(struct btrfs_trans_handle *trans,
struct btrfs_root *root, struct extent_buffer *buf,
struct extent_buffer *parent, int parent_slot,
- struct extent_buffer **cow_ret)
+ struct extent_buffer **cow_ret,
+ enum btrfs_lock_nesting nest)
{
struct btrfs_fs_info *fs_info = root->fs_info;
u64 search_start;
@@ -1485,7 +1488,7 @@ noinline int btrfs_cow_block(struct btrfs_trans_handle *trans,
*/
btrfs_qgroup_trace_subtree_after_cow(trans, root, buf);
ret = __btrfs_cow_block(trans, root, buf, parent,
- parent_slot, cow_ret, search_start, 0);
+ parent_slot, cow_ret, search_start, 0, nest);
trace_btrfs_cow_block(root, buf, *cow_ret);
@@ -1657,7 +1660,8 @@ int btrfs_realloc_node(struct btrfs_trans_handle *trans,
err = __btrfs_cow_block(trans, root, cur, parent, i,
&cur, search_start,
min(16 * blocksize,
- (end_slot - i) * blocksize));
+ (end_slot - i) * blocksize),
+ BTRFS_NESTING_COW);
if (err) {
btrfs_tree_unlock(cur);
free_extent_buffer(cur);
@@ -1855,7 +1859,8 @@ static noinline int balance_level(struct btrfs_trans_handle *trans,
btrfs_tree_lock(child);
btrfs_set_lock_blocking_write(child);
- ret = btrfs_cow_block(trans, root, child, mid, 0, &child);
+ ret = btrfs_cow_block(trans, root, child, mid, 0, &child,
+ BTRFS_NESTING_COW);
if (ret) {
btrfs_tree_unlock(child);
free_extent_buffer(child);
@@ -1894,7 +1899,8 @@ static noinline int balance_level(struct btrfs_trans_handle *trans,
btrfs_tree_lock(left);
btrfs_set_lock_blocking_write(left);
wret = btrfs_cow_block(trans, root, left,
- parent, pslot - 1, &left);
+ parent, pslot - 1, &left,
+ BTRFS_NESTING_COW);
if (wret) {
ret = wret;
goto enospc;
@@ -1909,7 +1915,8 @@ static noinline int balance_level(struct btrfs_trans_handle *trans,
btrfs_tree_lock(right);
btrfs_set_lock_blocking_write(right);
wret = btrfs_cow_block(trans, root, right,
- parent, pslot + 1, &right);
+ parent, pslot + 1, &right,
+ BTRFS_NESTING_COW);
if (wret) {
ret = wret;
goto enospc;
@@ -2077,7 +2084,8 @@ static noinline int push_nodes_for_insert(struct btrfs_trans_handle *trans,
wret = 1;
} else {
ret = btrfs_cow_block(trans, root, left, parent,
- pslot - 1, &left);
+ pslot - 1, &left,
+ BTRFS_NESTING_COW);
if (ret)
wret = 1;
else {
@@ -2132,7 +2140,7 @@ static noinline int push_nodes_for_insert(struct btrfs_trans_handle *trans,
} else {
ret = btrfs_cow_block(trans, root, right,
parent, pslot + 1,
- &right);
+ &right, BTRFS_NESTING_COW);
if (ret)
wret = 1;
else {
@@ -2740,11 +2748,13 @@ int btrfs_search_slot(struct btrfs_trans_handle *trans, struct btrfs_root *root,
btrfs_set_path_blocking(p);
if (last_level)
err = btrfs_cow_block(trans, root, b, NULL, 0,
- &b);
+ &b,
+ BTRFS_NESTING_COW);
else
err = btrfs_cow_block(trans, root, b,
p->nodes[level + 1],
- p->slots[level + 1], &b);
+ p->slots[level + 1], &b,
+ BTRFS_NESTING_COW);
if (err) {
ret = err;
goto done;
@@ -3396,7 +3406,8 @@ static noinline int insert_new_root(struct btrfs_trans_handle *trans,
btrfs_node_key(lower, &lower_key, 0);
c = alloc_tree_block_no_bg_flush(trans, root, 0, &lower_key, level,
- root->node->start, 0);
+ root->node->start, 0,
+ BTRFS_NESTING_NORMAL);
if (IS_ERR(c))
return PTR_ERR(c);
@@ -3526,7 +3537,7 @@ static noinline int split_node(struct btrfs_trans_handle *trans,
btrfs_node_key(c, &disk_key, mid);
split = alloc_tree_block_no_bg_flush(trans, root, 0, &disk_key, level,
- c->start, 0);
+ c->start, 0, BTRFS_NESTING_NORMAL);
if (IS_ERR(split))
return PTR_ERR(split);
@@ -3804,7 +3815,7 @@ static int push_leaf_right(struct btrfs_trans_handle *trans, struct btrfs_root
/* cow and double check */
ret = btrfs_cow_block(trans, root, right, upper,
- slot + 1, &right);
+ slot + 1, &right, BTRFS_NESTING_COW);
if (ret)
goto out_unlock;
@@ -4045,7 +4056,8 @@ static int push_leaf_left(struct btrfs_trans_handle *trans, struct btrfs_root
/* cow and double check */
ret = btrfs_cow_block(trans, root, left,
- path->nodes[1], slot - 1, &left);
+ path->nodes[1], slot - 1, &left,
+ BTRFS_NESTING_COW);
if (ret) {
/* we hit -ENOSPC, but it isn't fatal here */
if (ret == -ENOSPC)
@@ -4312,7 +4324,7 @@ static noinline int split_leaf(struct btrfs_trans_handle *trans,
btrfs_item_key(l, &disk_key, mid);
right = alloc_tree_block_no_bg_flush(trans, root, 0, &disk_key, 0,
- l->start, 0);
+ l->start, 0, BTRFS_NESTING_NORMAL);
if (IS_ERR(right))
return PTR_ERR(right);