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[82.81.193.202]) by smtp.gmail.com with ESMTPSA id 204sm20873841wmj.7.2017.01.23.04.32.41 (version=TLS1_2 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Mon, 23 Jan 2017 04:32:43 -0800 (PST) From: Amir Goldstein To: Miklos Szeredi Cc: Jan Kara , Al Viro , linux-unionfs@vger.kernel.org, linux-fsdevel@vger.kernel.org Subject: [RFC][PATCH v2 2/3] ovl: properly implement sync_filesystem() Date: Mon, 23 Jan 2017 14:32:21 +0200 Message-Id: <1485174742-15866-3-git-send-email-amir73il@gmail.com> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1485174742-15866-1-git-send-email-amir73il@gmail.com> References: <1485174742-15866-1-git-send-email-amir73il@gmail.com> Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP overlayfs syncs all inode pages on sync_filesystem(), but it also needs to call s_op->sync_fs() of upper fs for metadata sync. This fixes correctness of syncfs(2) as demonstrated by following xfs specific test: xfs_sync_stats() { echo $1 echo -n "xfs_log_force = " grep log /proc/fs/xfs/stat | awk '{ print $5 }' } xfs_sync_stats "before touch" touch x xfs_sync_stats "after touch" xfs_io -c syncfs . xfs_sync_stats "after syncfs" xfs_io -c fsync x xfs_sync_stats "after fsync" xfs_io -c fsync x xfs_sync_stats "after fsync #2" When this test is run in overlay mount over xfs, log force count does not increase with syncfs command. Signed-off-by: Amir Goldstein --- fs/overlayfs/super.c | 20 ++++++++++++++++++++ 1 file changed, 20 insertions(+) diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c index 6792bb7..346f668 100644 --- a/fs/overlayfs/super.c +++ b/fs/overlayfs/super.c @@ -160,6 +160,25 @@ static void ovl_put_super(struct super_block *sb) kfree(ufs); } +static int ovl_sync_fs(struct super_block *sb, int wait) +{ + struct ovl_fs *ufs = sb->s_fs_info; + struct super_block *upper_sb; + int ret; + + if (!ufs->upper_mnt) + return 0; + upper_sb = ufs->upper_mnt->mnt_sb; + if (!upper_sb->s_op->sync_fs) + return 0; + + /* real inodes have already been synced by sync_filesystem(ovl_sb) */ + down_read(&upper_sb->s_umount); + ret = upper_sb->s_op->sync_fs(upper_sb, wait); + up_read(&upper_sb->s_umount); + return ret; +} + /** * ovl_statfs * @sb: The overlayfs super block @@ -222,6 +241,7 @@ static int ovl_remount(struct super_block *sb, int *flags, char *data) static const struct super_operations ovl_super_operations = { .put_super = ovl_put_super, + .sync_fs = ovl_sync_fs, .statfs = ovl_statfs, .show_options = ovl_show_options, .remount_fs = ovl_remount,