From 52621cb6ed0e0e14358bb317bda7cd5fbd5c2a27 Mon Sep 17 00:00:00 2001 From: Li Zefan Date: Sun, 20 Nov 2011 07:33:38 -0500 Subject: [PATCH] Btrfs: avoid unnecessary bitmap search for cluster setup setup_cluster_no_bitmap() searches all the extents and bitmaps starting from offset. Therefore if it returns -ENOSPC, all the bitmaps starting from offset are in the bitmaps list, so it's sufficient to search from this list in setup_cluser_bitmap(). Signed-off-by: Li Zefan Signed-off-by: Chris Mason --- fs/btrfs/free-space-cache.c | 42 ++++--------------------------------- 1 file changed, 4 insertions(+), 38 deletions(-) diff --git a/fs/btrfs/free-space-cache.c b/fs/btrfs/free-space-cache.c index 8f792f41feab..8c32434da2cb 100644 --- a/fs/btrfs/free-space-cache.c +++ b/fs/btrfs/free-space-cache.c @@ -2451,7 +2451,6 @@ setup_cluster_bitmap(struct btrfs_block_group_cache *block_group, { struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl; struct btrfs_free_space *entry; - struct rb_node *node; int ret = -ENOSPC; u64 bitmap_offset = offset_to_bitmap(ctl, offset); @@ -2469,10 +2468,6 @@ setup_cluster_bitmap(struct btrfs_block_group_cache *block_group, list_add(&entry->list, bitmaps); } - /* - * First check our cached list of bitmaps and see if there is an entry - * here that will work. - */ list_for_each_entry(entry, bitmaps, list) { if (entry->bytes < min_bytes) continue; @@ -2483,38 +2478,10 @@ setup_cluster_bitmap(struct btrfs_block_group_cache *block_group, } /* - * If we do have entries on our list and we are here then we didn't find - * anything, so go ahead and get the next entry after the last entry in - * this list and start the search from there. + * The bitmaps list has all the bitmaps that record free space + * starting after offset, so no more search is required. */ - if (!list_empty(bitmaps)) { - entry = list_entry(bitmaps->prev, struct btrfs_free_space, - list); - node = rb_next(&entry->offset_index); - if (!node) - return -ENOSPC; - entry = rb_entry(node, struct btrfs_free_space, offset_index); - goto search; - } - - entry = tree_search_offset(ctl, offset_to_bitmap(ctl, offset), 0, 1); - if (!entry) - return -ENOSPC; - -search: - node = &entry->offset_index; - do { - entry = rb_entry(node, struct btrfs_free_space, offset_index); - node = rb_next(&entry->offset_index); - if (!entry->bitmap) - continue; - if (entry->bytes < min_bytes) - continue; - ret = btrfs_bitmap_cluster(block_group, entry, cluster, offset, - bytes, min_bytes); - } while (ret && node); - - return ret; + return -ENOSPC; } /* @@ -2532,8 +2499,8 @@ int btrfs_find_space_cluster(struct btrfs_trans_handle *trans, u64 offset, u64 bytes, u64 empty_size) { struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl; - struct list_head bitmaps; struct btrfs_free_space *entry, *tmp; + LIST_HEAD(bitmaps); u64 min_bytes; int ret; @@ -2572,7 +2539,6 @@ int btrfs_find_space_cluster(struct btrfs_trans_handle *trans, goto out; } - INIT_LIST_HEAD(&bitmaps); ret = setup_cluster_no_bitmap(block_group, cluster, &bitmaps, offset, bytes, min_bytes); if (ret) -- 2.39.5