btrfs: mark leaf space and overflow checks as unlikely on insert and extension

We have several sanity checks when inserting or extending items in a btree
that verify we didn't overflow the leaf or access a slot beyond the last
one. These are cases that are never expected to be hit so mark them as
unlikely, allowing the compiler to potentially generate better code.

Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Filipe Manana <fdmanana@suse.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 f6d2a4a4b9eb825462c04f7f9ae9e6fd4fc21eb6..dc185322362b3762e8266172f3ed9a1a7f9c1108 100644 (file)
--- a/fs/btrfs/ctree.c
+++ b/fs/btrfs/ctree.c
@@ -3086,7 +3086,7 @@ int btrfs_leaf_free_space(const struct extent_buffer *leaf)
        int ret;
 
        ret = BTRFS_LEAF_DATA_SIZE(fs_info) - leaf_space_used(leaf, 0, nritems);
-       if (ret < 0) {
+       if (unlikely(ret < 0)) {
                btrfs_crit(fs_info,
                           "leaf free space ret %d, leaf data size %lu, used %d nritems %d",
                           ret,
@@ -4075,7 +4075,7 @@ void btrfs_truncate_item(struct btrfs_trans_handle *trans,
        btrfs_set_item_size(leaf, slot, new_size);
        btrfs_mark_buffer_dirty(trans, leaf);
 
-       if (btrfs_leaf_free_space(leaf) < 0) {
+       if (unlikely(btrfs_leaf_free_space(leaf) < 0)) {
                btrfs_print_leaf(leaf);
                BUG();
        }
@@ -4108,7 +4108,7 @@ void btrfs_extend_item(struct btrfs_trans_handle *trans,
        old_data = btrfs_item_data_end(leaf, slot);
 
        BUG_ON(slot < 0);
-       if (slot >= nritems) {
+       if (unlikely(slot >= nritems)) {
                btrfs_print_leaf(leaf);
                btrfs_crit(leaf->fs_info, "slot %d too large, nritems %d",
                           slot, nritems);
@@ -4135,7 +4135,7 @@ void btrfs_extend_item(struct btrfs_trans_handle *trans,
        btrfs_set_item_size(leaf, slot, old_size + data_size);
        btrfs_mark_buffer_dirty(trans, leaf);
 
-       if (btrfs_leaf_free_space(leaf) < 0) {
+       if (unlikely(btrfs_leaf_free_space(leaf) < 0)) {
                btrfs_print_leaf(leaf);
                BUG();
        }
@@ -4183,7 +4183,7 @@ static void setup_items_for_insert(struct btrfs_trans_handle *trans,
        data_end = leaf_data_end(leaf);
        total_size = batch->total_data_size + (batch->nr * sizeof(struct btrfs_item));
 
-       if (btrfs_leaf_free_space(leaf) < total_size) {
+       if (unlikely(btrfs_leaf_free_space(leaf) < total_size)) {
                btrfs_print_leaf(leaf);
                btrfs_crit(fs_info, "not enough freespace need %u have %d",
                           total_size, btrfs_leaf_free_space(leaf));
@@ -4193,7 +4193,7 @@ static void setup_items_for_insert(struct btrfs_trans_handle *trans,
        if (slot != nritems) {
                unsigned int old_data = btrfs_item_data_end(leaf, slot);
 
-               if (old_data < data_end) {
+               if (unlikely(old_data < data_end)) {
                        btrfs_print_leaf(leaf);
                        btrfs_crit(fs_info,
                "item at slot %d with data offset %u beyond data end of leaf %u",
@@ -4232,7 +4232,7 @@ static void setup_items_for_insert(struct btrfs_trans_handle *trans,
        btrfs_set_header_nritems(leaf, nritems + batch->nr);
        btrfs_mark_buffer_dirty(trans, leaf);
 
-       if (btrfs_leaf_free_space(leaf) < 0) {
+       if (unlikely(btrfs_leaf_free_space(leaf) < 0)) {
                btrfs_print_leaf(leaf);
                BUG();
        }