btrfs: trimming some start_transaction() code away (f2f767e7) · Commits · 戴 / test

Just call kmem_cache_zalloc() instead of calling kmem_cache_alloc(). We're just initializing most fields to 0, false and NULL later on _anyway_, so to make the code mode readable and potentially gain a bit of performance (completely untested claim), we should fill our btrfs_trans_handle with zeros on allocation then just initialize those five remaining fields (not counting the list_heads) as normal. Reviewed-by:

David Sterba <dsterba@suse.com> Signed-off-by:

Alexandru Moise <00moses.alexander00@gmail.com> Signed-off-by:

David Sterba <dsterba@suse.com>

fs/btrfs/transaction.c

+1 −14

Original line number	Diff line number	Diff line
		@@ -502,7 +502,7 @@ start_transaction(struct btrfs_root *root, u64 num_items, unsigned int type,
		goto reserve_fail;
		}
		again:
		h = kmem_cache_alloc(btrfs_trans_handle_cachep, GFP_NOFS);
		h = kmem_cache_zalloc(btrfs_trans_handle_cachep, GFP_NOFS);
		if (!h) {
		ret = -ENOMEM;
		goto alloc_fail;
		@@ -543,23 +543,10 @@ again:

		h->transid = cur_trans->transid;
		h->transaction = cur_trans;
		h->blocks_used = 0;
		h->bytes_reserved = 0;
		h->chunk_bytes_reserved = 0;
		h->root = root;
		h->delayed_ref_updates = 0;
		h->use_count = 1;
		h->adding_csums = 0;
		h->block_rsv = NULL;
		h->orig_rsv = NULL;
		h->aborted = 0;
		h->qgroup_reserved = 0;
		h->delayed_ref_elem.seq = 0;
		h->type = type;
		h->allocating_chunk = false;
		h->can_flush_pending_bgs = true;
		h->reloc_reserved = false;
		h->sync = false;
		INIT_LIST_HEAD(&h->qgroup_ref_list);
		INIT_LIST_HEAD(&h->new_bgs);
		INIT_LIST_HEAD(&h->ordered);

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