From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from cn.fujitsu.com ([59.151.112.132]:49417 "EHLO heian.cn.fujitsu.com" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1751925AbbBYBTR convert rfc822-to-8bit (ORCPT ); Tue, 24 Feb 2015 20:19:17 -0500 From: Zhao Lei To: CC: References: <1424792249-26672-1-git-send-email-zhaolei@cn.fujitsu.com> In-Reply-To: Subject: RE: [PATCH 3/3] btrfs: Remove BUG_ON() when failed searching block_group_cache in unpin_extent_range() Date: Wed, 25 Feb 2015 09:18:46 +0800 Message-ID: <007f01d05099$01bc2430$05346c90$@cn.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Sender: linux-btrfs-owner@vger.kernel.org List-ID: Hi, Filipe > From: Filipe David Manana [mailto:fdmanana@gmail.com] > > On Tue, Feb 24, 2015 at 3:37 PM, Zhaolei wrote: > > From: Zhao Lei > > > > Above BUG_ON() was triggered only one time in my test, but hadn't > > happened again in same env. > > > > The reason maybe: > > A block group which include pinned space was removed before > > unpin_extent_range(), and no other block_group_cache after "start" > > pos, so the code entered into above BUG_ON(). > > > > To support auto-remove-bgs, we can remove above BUG_ON(), and bypass > > removed bgs. > > I don't think it's a good idea to remove this BUG_ON(). > You're just hiding (potentially dangerous) logical bugs doing that - we need to > understand exactly why that happens and fix it. > > I fixed a scenario where this happens recently, and the fix is in 4.0-rc1: > > https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=d4b4 > 50cd4b33ce7c572e7fdccf33b59c4cdf361c > > Were you testing with or without this fix? > Thanks for notice, it is better way of fix. I'll drop this patch. Thanks Zhaolei > Thanks > > > > > Signed-off-by: Zhao Lei > > --- > > fs/btrfs/extent-tree.c | 3 ++- > > 1 file changed, 2 insertions(+), 1 deletion(-) > > > > diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c index > > 8b51eb5..ef0b40d 100644 > > --- a/fs/btrfs/extent-tree.c > > +++ b/fs/btrfs/extent-tree.c > > @@ -5751,7 +5751,8 @@ static int unpin_extent_range(struct btrfs_root > *root, u64 start, u64 end, > > if (cache) > > btrfs_put_block_group(cache); > > cache = btrfs_lookup_block_group(fs_info, > start); > > - BUG_ON(!cache); /* Logic error */ > > + if (!cache) > > + break; > > } > > > > len = cache->key.objectid + cache->key.offset - start; > > -- > > 1.8.5.1 > > > > -- > > To unsubscribe from this list: send the line "unsubscribe linux-btrfs" > > in the body of a message to majordomo@vger.kernel.org More majordomo > > info at http://vger.kernel.org/majordomo-info.html > > > > -- > Filipe David Manana, > > "Reasonable men adapt themselves to the world. > Unreasonable men adapt the world to themselves. > That's why all progress depends on unreasonable men."