From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2D0B0C43140 for ; Thu, 5 Sep 2019 16:23:51 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id DFCA1207E0 for ; Thu, 5 Sep 2019 16:23:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726626AbfIEQXu (ORCPT ); Thu, 5 Sep 2019 12:23:50 -0400 Received: from verein.lst.de ([213.95.11.211]:50105 "EHLO verein.lst.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726008AbfIEQXt (ORCPT ); Thu, 5 Sep 2019 12:23:49 -0400 Received: by verein.lst.de (Postfix, from userid 2407) id 17F2468B05; Thu, 5 Sep 2019 18:23:44 +0200 (CEST) Date: Thu, 5 Sep 2019 18:23:44 +0200 From: Christoph Hellwig To: Goldwyn Rodrigues Cc: linux-fsdevel@vger.kernel.org, linux-btrfs@vger.kernel.org, darrick.wong@oracle.com, hch@lst.de, linux-xfs@vger.kernel.org, Goldwyn Rodrigues Subject: Re: [PATCH 04/15] btrfs: Add a simple buffered iomap write Message-ID: <20190905162344.GA22450@lst.de> References: <20190905150650.21089-1-rgoldwyn@suse.de> <20190905150650.21089-5-rgoldwyn@suse.de> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20190905150650.21089-5-rgoldwyn@suse.de> User-Agent: Mutt/1.5.17 (2007-11-01) Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org > Most of the code is "inspired" by > fs/btrfs/file.c. To keep the size small, all removals are in > following patches. Wouldn't it be better to massage the existing code into a form where you can fairly easily switch over to iomap? That is start refactoring the code into helpers that are mostly reusable and then just have a patch switching over. That helps reviewing what actually changes. It's also what we did for XFS. > + if (!ordered) { > + break; > + } No need for the braces. > +static void btrfs_buffered_page_done(struct inode *inode, loff_t pos, > + unsigned copied, struct page *page, > + struct iomap *iomap) > +{ > + if (!page) > + return; > + SetPageUptodate(page); > + ClearPageChecked(page); > + set_page_dirty(page); > + get_page(page); > +} Thіs looks really strange. Can you explain me why you need the manual dirtying and SetPageUptodate, and an additional page refcount here? > + if (ret < 0) { > + /* > + * Space allocation failed. Let's check if we can > + * continue I/O without allocations > + */ > + if ((BTRFS_I(inode)->flags & (BTRFS_INODE_NODATACOW | > + BTRFS_INODE_PREALLOC)) && > + check_can_nocow(BTRFS_I(inode), pos, > + &write_bytes) > 0) { > + bi->nocow = true; > + /* > + * our prealloc extent may be smaller than > + * write_bytes, so scale down. > + */ > + bi->reserved_bytes = round_up(write_bytes + > + sector_offset, > + fs_info->sectorsize); > + } else { > + goto error; > + } Maybe move the goto into the inverted if so you can reduce indentation by one level? > + } else { > + u64 __pos = round_down(pos + written, fs_info->sectorsize); Line over > 80 characters, and a somewhat odd variabke name. > + if (bi->nocow) { > + struct btrfs_root *root = BTRFS_I(inode)->root; > + btrfs_end_write_no_snapshotting(root); > + if (written > 0) { > + u64 start = round_down(pos, fs_info->sectorsize); > + u64 end = round_up(pos + written, fs_info->sectorsize) - 1; Line > 80 chars. > + set_extent_bit(&BTRFS_I(inode)->io_tree, start, end, > + EXTENT_NORESERVE, NULL, NULL, GFP_NOFS); > + } > + > + } > + btrfs_delalloc_release_extents(BTRFS_I(inode), bi->reserved_bytes, > + true); > + > + if (written < fs_info->nodesize) > + btrfs_btree_balance_dirty(fs_info); > + > + extent_changeset_free(bi->data_reserved); > + kfree(bi); > + return ret; > +} > +static const struct iomap_ops btrfs_buffered_iomap_ops = { > + .iomap_begin = btrfs_buffered_iomap_begin, > + .iomap_end = btrfs_buffered_iomap_end, > +}; > + > +size_t btrfs_buffered_iomap_write(struct kiocb *iocb, struct iov_iter *from) > +{ > + ssize_t written; > + struct inode *inode = file_inode(iocb->ki_filp); > + written = iomap_file_buffered_write(iocb, from, &btrfs_buffered_iomap_ops); no empty line after the variable declarations? Also this adds a > 80 character line. > + if (written > 0) > + iocb->ki_pos += written; I wonder if we should fold the ki_pos update into iomap_file_buffered_write. But the patch looks fine even without that. Also any reason to not name this function btrfs_buffered_write and keep it in file.c with the rest of the write code?