From: Christoph Hellwig Subject: [PATCH 1/2] ext4: fix DAX write locking Date: Tue, 10 Jan 2017 16:48:07 +0100 Message-ID: <1484063288-18255-2-git-send-email-hch@lst.de> References: <1484063288-18255-1-git-send-email-hch@lst.de> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Cc: linux-ext4@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-nvdimm@lists.01.org To: Jan Kara Return-path: Received: from bombadil.infradead.org ([198.137.202.9]:56288 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933520AbdAJPsO (ORCPT ); Tue, 10 Jan 2017 10:48:14 -0500 In-Reply-To: <1484063288-18255-1-git-send-email-hch@lst.de> Sender: linux-ext4-owner@vger.kernel.org List-ID: Unlike O_DIRECT DAX is not an optional opt-in feature selected by the application, so we'll have to provide the traditional synchronŃ–zation of overlapping writes as we do for buffered writes. This was broken historically for DAX, but got fixed for ext2 and XFS as part of the iomap conversion. Fix up ext4 as well. Signed-off-by: Christoph Hellwig --- fs/ext4/file.c | 10 +--------- 1 file changed, 1 insertion(+), 9 deletions(-) diff --git a/fs/ext4/file.c b/fs/ext4/file.c index d663d3d..a1e88aa 100644 --- a/fs/ext4/file.c +++ b/fs/ext4/file.c @@ -175,7 +175,6 @@ ext4_dax_write_iter(struct kiocb *iocb, struct iov_iter *from) { struct inode *inode = file_inode(iocb->ki_filp); ssize_t ret; - bool overwrite = false; inode_lock(inode); ret = ext4_write_checks(iocb, from); @@ -188,16 +187,9 @@ ext4_dax_write_iter(struct kiocb *iocb, struct iov_iter *from) if (ret) goto out; - if (ext4_overwrite_io(inode, iocb->ki_pos, iov_iter_count(from))) { - overwrite = true; - downgrade_write(&inode->i_rwsem); - } ret = dax_iomap_rw(iocb, from, &ext4_iomap_ops); out: - if (!overwrite) - inode_unlock(inode); - else - inode_unlock_shared(inode); + inode_unlock(inode); if (ret > 0) ret = generic_write_sync(iocb, ret); return ret; -- 2.1.4