From a5e681d9bd641c4f0677e87d3a0c92a8f4f16293 Mon Sep 17 00:00:00 2001 From: Josef Bacik Date: Thu, 1 Oct 2015 14:54:10 -0400 Subject: [PATCH] Btrfs: cut down on loops through the allocator We try really really hard to make allocations, but sometimes it is just not going to happen, especially when free space is extremely fragmented. So add a few short cuts through the looping states. For example if we couldn't allocate a chunk, just go straight to the NO_EMPTY_SIZE loop. If there are no uncached block groups and we've done a full search, go straight to the ALLOC_CHUNK stage. And finally if we already have empty_size and empty_cluster set to 0 go ahead and return -ENOSPC. Thanks, Signed-off-by: Josef Bacik Signed-off-by: Chris Mason --- fs/btrfs/extent-tree.c | 39 ++++++++++++++++++++++++++++++++++++--- 1 file changed, 36 insertions(+), 3 deletions(-) diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c index 3185c457f025..9f18eb0e86b6 100644 --- a/fs/btrfs/extent-tree.c +++ b/fs/btrfs/extent-tree.c @@ -6921,6 +6921,7 @@ static noinline int find_free_extent(struct btrfs_root *orig_root, bool failed_alloc = false; bool use_cluster = true; bool have_caching_bg = false; + bool full_search = false; WARN_ON(num_bytes < root->sectorsize); ins->type = BTRFS_EXTENT_ITEM_KEY; @@ -7023,6 +7024,8 @@ static noinline int find_free_extent(struct btrfs_root *orig_root, } search: have_caching_bg = false; + if (index == 0 || index == __get_raid_index(flags)) + full_search = true; down_read(&space_info->groups_sem); list_for_each_entry(block_group, &space_info->block_groups[index], list) { @@ -7056,6 +7059,7 @@ search: have_block_group: cached = block_group_cache_done(block_group); if (unlikely(!cached)) { + have_caching_bg = true; ret = cache_block_group(block_group, 0); BUG_ON(ret < 0); ret = 0; @@ -7228,8 +7232,6 @@ unclustered_alloc: failed_alloc = true; goto have_block_group; } else if (!offset) { - if (!cached) - have_caching_bg = true; goto loop; } checks: @@ -7286,7 +7288,20 @@ loop: */ if (!ins->objectid && loop < LOOP_NO_EMPTY_SIZE) { index = 0; - loop++; + if (loop == LOOP_CACHING_NOWAIT) { + /* + * We want to skip the LOOP_CACHING_WAIT step if we + * don't have any unached bgs and we've alrelady done a + * full search through. + */ + if (have_caching_bg || !full_search) + loop = LOOP_CACHING_WAIT; + else + loop = LOOP_ALLOC_CHUNK; + } else { + loop++; + } + if (loop == LOOP_ALLOC_CHUNK) { struct btrfs_trans_handle *trans; int exist = 0; @@ -7304,6 +7319,15 @@ loop: ret = do_chunk_alloc(trans, root, flags, CHUNK_ALLOC_FORCE); + + /* + * If we can't allocate a new chunk we've already looped + * through at least once, move on to the NO_EMPTY_SIZE + * case. + */ + if (ret == -ENOSPC) + loop = LOOP_NO_EMPTY_SIZE; + /* * Do not bail out on ENOSPC since we * can do more things. @@ -7320,6 +7344,15 @@ loop: } if (loop == LOOP_NO_EMPTY_SIZE) { + /* + * Don't loop again if we already have no empty_size and + * no empty_cluster. + */ + if (empty_size == 0 && + empty_cluster == 0) { + ret = -ENOSPC; + goto out; + } empty_size = 0; empty_cluster = 0; } -- 2.20.1