Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752869AbaFWKOp (ORCPT ); Mon, 23 Jun 2014 06:14:45 -0400 Received: from cn.fujitsu.com ([59.151.112.132]:62179 "EHLO heian.cn.fujitsu.com" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1752565AbaFWKOo convert rfc822-to-8bit (ORCPT ); Mon, 23 Jun 2014 06:14:44 -0400 X-IronPort-AV: E=Sophos;i="5.00,760,1396972800"; d="scan'208";a="32282713" Message-ID: <53A7FE82.3070303@cn.fujitsu.com> Date: Mon, 23 Jun 2014 18:16:34 +0800 From: Miao Xie Reply-To: User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.6.0 MIME-Version: 1.0 To: Geert Uytterhoeven , Chris Mason , Josef Bacik CC: , Subject: Re: [PATCH] Btrfs: Refactor btrfs_lock_cluster() to kill compiler warning References: <1403440209-13370-1-git-send-email-geert@linux-m68k.org> In-Reply-To: <1403440209-13370-1-git-send-email-geert@linux-m68k.org> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8BIT X-Originating-IP: [10.167.226.169] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, 22 Jun 2014 14:30:09 +0200, Geert Uytterhoeven wrote: > fs/btrfs/extent-tree.c: In function ‘btrfs_lock_cluster’: > fs/btrfs/extent-tree.c:6399: warning: ‘used_bg’ may be used uninitialized in this function > > - Replace "again: ... goto again;" by standard C "while (1) { ... }", > - Move block not processed during the first iteration of the loop to the > end of the loop, which allows to kill the "locked" variable, > > Signed-off-by: Geert Uytterhoeven Looks good to me. Reviewed-and-Tested-by: Miao Xie > --- > Please review, compile tested only. > --- > fs/btrfs/extent-tree.c | 42 ++++++++++++++++++++---------------------- > 1 file changed, 20 insertions(+), 22 deletions(-) > > diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c > index 99c253918208..e151c4a73d7b 100644 > --- a/fs/btrfs/extent-tree.c > +++ b/fs/btrfs/extent-tree.c > @@ -6397,36 +6397,34 @@ btrfs_lock_cluster(struct btrfs_block_group_cache *block_group, > int delalloc) > { > struct btrfs_block_group_cache *used_bg; > - bool locked = false; > -again: > + > spin_lock(&cluster->refill_lock); > - if (locked) { > - if (used_bg == cluster->block_group) > - return used_bg; > + while (1) { > + used_bg = cluster->block_group; > + if (!used_bg) > + return NULL; > > - up_read(&used_bg->data_rwsem); > - btrfs_put_block_group(used_bg); > - } > + if (used_bg == block_group) > + return used_bg; > > - used_bg = cluster->block_group; > - if (!used_bg) > - return NULL; > + btrfs_get_block_group(used_bg); > > - if (used_bg == block_group) > - return used_bg; > + if (!delalloc) > + return used_bg; > > - btrfs_get_block_group(used_bg); > + if (down_read_trylock(&used_bg->data_rwsem)) > + return used_bg; > > - if (!delalloc) > - return used_bg; > + spin_unlock(&cluster->refill_lock); > + down_read(&used_bg->data_rwsem); > > - if (down_read_trylock(&used_bg->data_rwsem)) > - return used_bg; > + spin_lock(&cluster->refill_lock); > + if (used_bg == cluster->block_group) > + return used_bg; > > - spin_unlock(&cluster->refill_lock); > - down_read(&used_bg->data_rwsem); > - locked = true; > - goto again; > + up_read(&used_bg->data_rwsem); > + btrfs_put_block_group(used_bg); > + } > } > > static inline void > -- 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/