From: "Takashi Sato" Subject: Re: [PATCH 2/3] Implement generic freeze feature Date: Tue, 28 Oct 2008 21:33:59 +0900 Message-ID: References: <20081027215855t-sato@mail.jp.nec.com> <20081027231533.96c42a78.akpm@linux-foundation.org> Reply-To: device-mapper development Mime-Version: 1.0 Content-Type: text/plain; format=flowed; charset="iso-8859-1"; reply-type=original Content-Transfer-Encoding: 7bit Cc: axboe@kernel.dk, mtk.manpages@googlemail.com, linux-kernel@vger.kernel.org, xfs@oss.sgi.com, Christoph Hellwig , dm-devel@redhat.com, viro@ZenIV.linux.org.uk, linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org To: "Andrew Morton" Return-path: In-Reply-To: <20081027231533.96c42a78.akpm@linux-foundation.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: dm-devel-bounces@redhat.com Errors-To: dm-devel-bounces@redhat.com List-Id: linux-ext4.vger.kernel.org Hi, >> -void thaw_bdev(struct block_device *bdev, struct super_block *sb) >> +int thaw_bdev(struct block_device *bdev, struct super_block *sb) >> { >> + int error = 0; >> + >> + mutex_lock(&bdev->bd_fsfreeze_mutex); >> + if (!bdev->bd_fsfreeze_count) { >> + mutex_unlock(&bdev->bd_fsfreeze_mutex); >> + return -EINVAL; > > This would be a programming error, yes? This is not a kernel programming error but a user's. thaw_bdev() is called via the unfreeze ioctl. If a user calls the unfreeze ioctl for an unfrozen filesystem, this error will be returned. So a WARN_ON isn't needed. > If so, a WARN_ON is more appropriate than a silent runtime error. > >> + } Cheers, Takashi