From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wm0-f67.google.com ([74.125.82.67]:35482 "EHLO mail-wm0-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751207AbdAWMdM (ORCPT ); Mon, 23 Jan 2017 07:33:12 -0500 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 1/3] vfs: freeze protect overlay inode on file_start_write() Date: Mon, 23 Jan 2017 14:32:20 +0200 Message-Id: <1485174742-15866-2-git-send-email-amir73il@gmail.com> 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 List-ID: Before writing to overlay file, need to check if either overlay or upper fs are frozen. This allows freezing overlayfs mount independently of freezing underlying fs. Signed-off-by: Amir Goldstein --- include/linux/fs.h | 17 ++++++++++++++++- 1 file changed, 16 insertions(+), 1 deletion(-) diff --git a/include/linux/fs.h b/include/linux/fs.h index 4a7f3cc..71811be 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -2547,14 +2547,26 @@ static inline void file_start_write(struct file *file) { if (!S_ISREG(file_inode(file)->i_mode)) return; + __sb_start_write(locks_inode(file)->i_sb, SB_FREEZE_WRITE, true); + if (likely(locks_inode(file) == file_inode(file))) + return; __sb_start_write(file_inode(file)->i_sb, SB_FREEZE_WRITE, true); + } static inline bool file_start_write_trylock(struct file *file) { + int ret; + if (!S_ISREG(file_inode(file)->i_mode)) return true; - return __sb_start_write(file_inode(file)->i_sb, SB_FREEZE_WRITE, false); + ret = __sb_start_write(locks_inode(file)->i_sb, SB_FREEZE_WRITE, false); + if (!ret || likely(locks_inode(file) == file_inode(file))) + return ret; + ret = __sb_start_write(file_inode(file)->i_sb, SB_FREEZE_WRITE, false); + if (!ret) + __sb_end_write(locks_inode(file)->i_sb, SB_FREEZE_WRITE); + return ret; } static inline void file_end_write(struct file *file) @@ -2562,6 +2574,9 @@ static inline void file_end_write(struct file *file) if (!S_ISREG(file_inode(file)->i_mode)) return; __sb_end_write(file_inode(file)->i_sb, SB_FREEZE_WRITE); + if (likely(locks_inode(file) == file_inode(file))) + return; + __sb_end_write(locks_inode(file)->i_sb, SB_FREEZE_WRITE); } /* -- 2.7.4