From 009d9bea49b4c78769da52b800412fb163ff0ae7 Mon Sep 17 00:00:00 2001 From: Filipe Manana Date: Wed, 17 Aug 2022 12:22:38 +0100 Subject: [PATCH] btrfs: avoid memory allocation at log_new_dir_dentries() for common case At log_new_dir_dentries() we always start by allocating a list element for the starting inode and then do a while loop with the condition being a list emptiness check. This however is not needed, we can avoid allocating this initial list element and then just check for the list emptiness at the end of the loop's body. So just do that to save one memory allocation from the kmalloc-32 slab. This allows for not doing any memory allocation when we don't have any subdirectory to log, which is a very common case. Signed-off-by: Filipe Manana Signed-off-by: David Sterba --- fs/btrfs/tree-log.c | 29 ++++++++++++----------------- 1 file changed, 12 insertions(+), 17 deletions(-) diff --git a/fs/btrfs/tree-log.c b/fs/btrfs/tree-log.c index 0f084ab..ea80723 100644 --- a/fs/btrfs/tree-log.c +++ b/fs/btrfs/tree-log.c @@ -6117,6 +6117,7 @@ static int log_new_dir_dentries(struct btrfs_trans_handle *trans, struct btrfs_path *path; LIST_HEAD(dir_list); struct btrfs_dir_list *dir_elem; + u64 ino = btrfs_ino(start_inode); int ret = 0; /* @@ -6131,28 +6132,13 @@ static int log_new_dir_dentries(struct btrfs_trans_handle *trans, if (!path) return -ENOMEM; - dir_elem = kmalloc(sizeof(*dir_elem), GFP_NOFS); - if (!dir_elem) { - btrfs_free_path(path); - return -ENOMEM; - } - dir_elem->ino = btrfs_ino(start_inode); - list_add_tail(&dir_elem->list, &dir_list); - - while (!list_empty(&dir_list)) { + while (true) { struct extent_buffer *leaf; struct btrfs_key min_key; - u64 ino; bool continue_curr_inode = true; int nritems; int i; - dir_elem = list_first_entry(&dir_list, struct btrfs_dir_list, - list); - ino = dir_elem->ino; - list_del(&dir_elem->list); - kfree(dir_elem); - min_key.objectid = ino; min_key.type = BTRFS_DIR_INDEX_KEY; min_key.offset = 0; @@ -6163,7 +6149,7 @@ again: break; } else if (ret > 0) { ret = 0; - continue; + goto next; } leaf = path->nodes[0]; @@ -6226,6 +6212,15 @@ again: min_key.offset++; goto again; } + +next: + if (list_empty(&dir_list)) + break; + + dir_elem = list_first_entry(&dir_list, struct btrfs_dir_list, list); + ino = dir_elem->ino; + list_del(&dir_elem->list); + kfree(dir_elem); } out: btrfs_free_path(path); -- 2.7.4