From mboxrd@z Thu Jan 1 00:00:00 1970 From: Oleg Nesterov Subject: [PATCH 4/4] change thaw_super() to re-acquire s_writers.lock_map Date: Mon, 20 Jul 2015 19:01:09 +0200 Message-ID: <20150720170109.GA3909@redhat.com> References: <20150720170044.GA3868@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org To: Al Viro , Dave Chinner , Dave Hansen , Jan Kara Return-path: Content-Disposition: inline In-Reply-To: <20150720170044.GA3868@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: linux-fsdevel.vger.kernel.org Change thaw_super() to re-acquire the "write" locks we are going to release. This way s_op->unfreeze_fs(sb) is called with these locks held as it seen by lockdep, and this matches the reality. This adds another trivial helper, sb_freeze_acquire(). Signed-off-by: Oleg Nesterov --- fs/super.c | 12 ++++++++++++ 1 files changed, 12 insertions(+), 0 deletions(-) diff --git a/fs/super.c b/fs/super.c index e7ea9f1..b4db3ee 100644 --- a/fs/super.c +++ b/fs/super.c @@ -1263,6 +1263,14 @@ static void sb_freeze_release(struct super_block *sb) rwsem_release(sb->s_writers.lock_map + level, 1, _THIS_IP_); } +static void sb_freeze_acquire(struct super_block *sb) +{ + int level; + + for (level = 0; level < SB_FREEZE_LEVELS; ++level) + rwsem_acquire(sb->s_writers.lock_map + level, 0, 1, _THIS_IP_); +} + /** * freeze_super - lock the filesystem and force it into a consistent state * @sb: the super to lock @@ -1386,16 +1394,20 @@ int thaw_super(struct super_block *sb) if (sb->s_flags & MS_RDONLY) goto out; + sb_freeze_acquire(sb); + if (sb->s_op->unfreeze_fs) { error = sb->s_op->unfreeze_fs(sb); if (error) { printk(KERN_ERR "VFS:Filesystem thaw failed\n"); + sb_freeze_release(sb); up_write(&sb->s_umount); return error; } } + sb_freeze_release(sb); out: sb->s_writers.frozen = SB_UNFROZEN; smp_wmb(); -- 1.5.5.1