From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 354341D0956; Wed, 2 Oct 2024 14:13:16 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1727878397; cv=none; b=OXfcNNg+2x/19c3boiAt0/HkgwWXsBWD6UlKC2Dq7QC2ols3w3BeJzNM2UoyvSYMx7EiYAPcSCTY7JPNFZyG95uu9AJ0tUGoMbG695/2yYSAgp8Yx6w9OI+2Mcxkdv6uguvAXtpc9VsxJ1GhmDGV3Ye8SqyP41scssjV2w11rTs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1727878397; c=relaxed/simple; bh=kyfqQXbam9dZT4/sFEi+T6AW6veyJZsaZ4CV9cQ311o=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=B/fH7sqTIcBeGBKH5fbqEWj5uUhYq/VSxwmdmz4kCmI0fe5vC9ap2rse480q4qieeINkyE8ZJVODBkr/YvA3ilNsIK/VE485fjn8E+8bYYQIOdt6jy5U4JB+ffAqLjj42OxbStAhDdxELNPOMaLCmr8Lxi1Au37YGuT7zWVKdFY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=P/8jJqFe; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="P/8jJqFe" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7646FC4CEC2; Wed, 2 Oct 2024 14:13:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1727878396; bh=kyfqQXbam9dZT4/sFEi+T6AW6veyJZsaZ4CV9cQ311o=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=P/8jJqFeOLNLgh4R8GyG7YExci0qUqhXG6J+DY7HCaWSmQFDDfOYnF+/4O0pW+rjr J//Alr09aNMymZef2O7j0H5xhn7En22SZJ/aIkKZck9oVjrIR34M8jclwQptXojxo6 LyKtScO+3JFST3SXVvIqiwWnqeddrfCudqXxFJEU= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Chao Yu , Jaegeuk Kim , Sasha Levin Subject: [PATCH 6.10 398/634] f2fs: fix to avoid racing in between read and OPU dio write Date: Wed, 2 Oct 2024 14:58:18 +0200 Message-ID: <20241002125826.814957574@linuxfoundation.org> X-Mailer: git-send-email 2.46.2 In-Reply-To: <20241002125811.070689334@linuxfoundation.org> References: <20241002125811.070689334@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.10-stable review patch. If anyone has any objections, please let me know. ------------------ From: Chao Yu [ Upstream commit 0cac51185e65dc2a20686184e02f3cafc99eb202 ] If lfs mode is on, buffered read may race w/ OPU dio write as below, it may cause buffered read hits unwritten data unexpectly, and for dio read, the race condition exists as well. Thread A Thread B - f2fs_file_write_iter - f2fs_dio_write_iter - __iomap_dio_rw - f2fs_iomap_begin - f2fs_map_blocks - __allocate_data_block - allocated blkaddr #x - iomap_dio_submit_bio - f2fs_file_read_iter - filemap_read - f2fs_read_data_folio - f2fs_mpage_readpages - f2fs_map_blocks : get blkaddr #x - f2fs_submit_read_bio IRQ - f2fs_read_end_io : read IO on blkaddr #x complete IRQ - iomap_dio_bio_end_io : direct write IO on blkaddr #x complete In LFS mode, if there is inflight dio, let's wait for its completion, this policy won't cover all race cases, however it is a tradeoff which avoids abusing lock around IO paths. Fixes: f847c699cff3 ("f2fs: allow out-place-update for direct IO in LFS mode") Signed-off-by: Chao Yu Signed-off-by: Jaegeuk Kim Signed-off-by: Sasha Levin --- fs/f2fs/file.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c index fa6299a88492f..ad326c0ab5bd7 100644 --- a/fs/f2fs/file.c +++ b/fs/f2fs/file.c @@ -4590,6 +4590,10 @@ static ssize_t f2fs_file_read_iter(struct kiocb *iocb, struct iov_iter *to) f2fs_trace_rw_file_path(iocb->ki_filp, iocb->ki_pos, iov_iter_count(to), READ); + /* In LFS mode, if there is inflight dio, wait for its completion */ + if (f2fs_lfs_mode(F2FS_I_SB(inode))) + inode_dio_wait(inode); + if (f2fs_should_use_dio(inode, iocb, to)) { ret = f2fs_dio_read_iter(iocb, to); } else { -- 2.43.0