Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754029Ab0HXA7S (ORCPT ); Mon, 23 Aug 2010 20:59:18 -0400 Received: from cn.fujitsu.com ([222.73.24.84]:51303 "EHLO song.cn.fujitsu.com" rhost-flags-OK-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1753966Ab0HXA7R (ORCPT ); Mon, 23 Aug 2010 20:59:17 -0400 Message-ID: <4C731A8D.2010402@cn.fujitsu.com> Date: Tue, 24 Aug 2010 09:04:13 +0800 From: Li Zefan User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.9.1b3pre) Gecko/20090513 Fedora/3.0-2.3.beta2.fc11 Thunderbird/3.0b2 MIME-Version: 1.0 To: Josef Bacik CC: Chris Mason , linux-btrfs@vger.kernel.org, LKML Subject: Re: [PATCH 6/6] btrfs: check mergeable free space when removing a cluster References: <4C71CD4B.10606@cn.fujitsu.com> <4C71CDB7.6000602@cn.fujitsu.com> <20100823131504.GE2404@localhost.localdomain> In-Reply-To: <20100823131504.GE2404@localhost.localdomain> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4051 Lines: 107 Josef Bacik wrote: > On Mon, Aug 23, 2010 at 09:24:07AM +0800, Li Zefan wrote: >> After returing extents from a cluster to the block group, some >> extents in the block group may be mergeable. >> >> Signed-off-by: Li Zefan >> --- >> fs/btrfs/free-space-cache.c | 26 ++++++++++++++++++++------ >> 1 files changed, 20 insertions(+), 6 deletions(-) >> >> diff --git a/fs/btrfs/free-space-cache.c b/fs/btrfs/free-space-cache.c >> index faeec8f..c11f4f7 100644 >> --- a/fs/btrfs/free-space-cache.c >> +++ b/fs/btrfs/free-space-cache.c >> @@ -234,11 +234,18 @@ tree_search_offset(struct btrfs_block_group_cache *block_group, >> return entry; >> } >> >> -static void unlink_free_space(struct btrfs_block_group_cache *block_group, >> - struct btrfs_free_space *info) >> +static inline void >> +__unlink_free_space(struct btrfs_block_group_cache *block_group, >> + struct btrfs_free_space *info) >> { >> rb_erase(&info->offset_index, &block_group->free_space_offset); >> block_group->free_extents--; >> +} >> + >> +static void unlink_free_space(struct btrfs_block_group_cache *block_group, >> + struct btrfs_free_space *info) >> +{ >> + __unlink_free_space(block_group, info); >> block_group->free_space -= info->bytes; >> } >> >> @@ -611,7 +618,7 @@ out: >> } >> >> bool try_merge_free_space(struct btrfs_block_group_cache *block_group, >> - struct btrfs_free_space *info) >> + struct btrfs_free_space *info, bool update_stat) >> { >> struct btrfs_free_space *left_info; >> struct btrfs_free_space *right_info; >> @@ -632,7 +639,10 @@ bool try_merge_free_space(struct btrfs_block_group_cache *block_group, >> left_info = tree_search_offset(block_group, offset - 1, 0, 0); >> >> if (right_info && !right_info->bitmap) { >> - unlink_free_space(block_group, right_info); >> + if (update_stat) >> + unlink_free_space(block_group, right_info); >> + else >> + __unlink_free_space(block_group, right_info); >> info->bytes += right_info->bytes; >> kfree(right_info); >> merged = true; >> @@ -640,7 +650,10 @@ bool try_merge_free_space(struct btrfs_block_group_cache *block_group, >> >> if (left_info && !left_info->bitmap && >> left_info->offset + left_info->bytes == offset) { >> - unlink_free_space(block_group, left_info); >> + if (update_stat) >> + unlink_free_space(block_group, left_info); >> + else >> + __unlink_free_space(block_group, left_info); >> info->offset = left_info->offset; >> info->bytes += left_info->bytes; >> kfree(left_info); >> @@ -665,7 +678,7 @@ int btrfs_add_free_space(struct btrfs_block_group_cache *block_group, >> >> spin_lock(&block_group->tree_lock); >> >> - if (try_merge_free_space(block_group, info)) >> + if (try_merge_free_space(block_group, info, true)) >> goto link; >> >> /* >> @@ -883,6 +896,7 @@ __btrfs_return_cluster_to_free_space( >> node = rb_next(&entry->offset_index); >> rb_erase(&entry->offset_index, &cluster->root); >> BUG_ON(entry->bitmap); >> + try_merge_free_space(block_group, entry, false); >> tree_insert_offset(&block_group->free_space_offset, >> entry->offset, &entry->offset_index, 0); > > It's early in the morning here, so forgive me if I'm missing something obvious, > but if try_merge_free_space() succeeds here, then won't tree_insert_offset() > then add an entry that overlaps the same spot? Should we do something like > > merged = try_merge_free_space(); > if (!merged) > tree_insert_offset(); > > ? Thanks, > In try_merge_free_space() we try to merge the left and right entry into @entry, and then the caller has to insert the @entry into the tree by itself. Similarly, In btrfs_add_free_space() we call link_free_space() no matter try_merge_free_space() returns success or not. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/