From mboxrd@z Thu Jan 1 00:00:00 1970 From: Li Zefan Subject: [PATCH 1/6] btrfs: fix threshold calculation for block groups smaller than 1GB Date: Mon, 23 Aug 2010 09:22:40 +0800 Message-ID: <4C71CD60.5050507@cn.fujitsu.com> References: <4C71CD4B.10606@cn.fujitsu.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Cc: Josef Bacik , linux-btrfs@vger.kernel.org, LKML To: Chris Mason Return-path: In-Reply-To: <4C71CD4B.10606@cn.fujitsu.com> List-ID: If a block group is smaller than 1GB, the extent entry threadhold calculation will always set the threshold to 0. So as free space gets fragmented, btrfs will switch to use bitmap to manage free space, but then will never switch back to extents due to this bug. Signed-off-by: Li Zefan --- fs/btrfs/free-space-cache.c | 8 ++++++-- 1 files changed, 6 insertions(+), 2 deletions(-) diff --git a/fs/btrfs/free-space-cache.c b/fs/btrfs/free-space-cache.c index f488fac..7edbef6 100644 --- a/fs/btrfs/free-space-cache.c +++ b/fs/btrfs/free-space-cache.c @@ -263,14 +263,18 @@ static void recalculate_thresholds(struct btrfs_block_group_cache *block_group) u64 max_bytes; u64 bitmap_bytes; u64 extent_bytes; + u64 size = block_group->key.offset; /* * The goal is to keep the total amount of memory used per 1gb of space * at or below 32k, so we need to adjust how much memory we allow to be * used by extent based free space tracking */ - max_bytes = MAX_CACHE_BYTES_PER_GIG * - (div64_u64(block_group->key.offset, 1024 * 1024 * 1024)); + if (size < 1024 * 1024 * 1024) + max_bytes = MAX_CACHE_BYTES_PER_GIG; + else + max_bytes = MAX_CACHE_BYTES_PER_GIG * + div64_u64(size, 1024 * 1024 * 1024); /* * we want to account for 1 more bitmap than what we have so we can make -- 1.7.0.1