From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from verein.lst.de (verein.lst.de [213.95.11.211]) (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 D7B793FC8 for ; Mon, 23 Aug 2021 13:16:45 +0000 (UTC) Received: by verein.lst.de (Postfix, from userid 2407) id AABAC67357; Mon, 23 Aug 2021 15:16:42 +0200 (CEST) Date: Mon, 23 Aug 2021 15:16:42 +0200 From: Christoph Hellwig To: Shiyang Ruan Cc: djwong@kernel.org, hch@lst.de, linux-xfs@vger.kernel.org, dan.j.williams@intel.com, david@fromorbit.com, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, nvdimm@lists.linux.dev, rgoldwyn@suse.de, viro@zeniv.linux.org.uk, willy@infradead.org, Goldwyn Rodrigues Subject: Re: [PATCH v7 6/8] fsdax: Dedup file range to use a compare function Message-ID: <20210823131642.GD15536@lst.de> References: <20210816060359.1442450-1-ruansy.fnst@fujitsu.com> <20210816060359.1442450-7-ruansy.fnst@fujitsu.com> Precedence: bulk X-Mailing-List: nvdimm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210816060359.1442450-7-ruansy.fnst@fujitsu.com> User-Agent: Mutt/1.5.17 (2007-11-01) On Mon, Aug 16, 2021 at 02:03:57PM +0800, Shiyang Ruan wrote: > + id = dax_read_lock(); > + while ((ret = iomap_iter2(&it_src, &it_dest, ops)) > 0) { > + it_src.processed = it_dest.processed = > + dax_range_compare_iter(&it_src, &it_dest, same); > + } > + dax_read_unlock(id); I think it would be better to move the DAX locking into dax_range_compare_iter to avoid very long hold times. > + return ret; > +} > +EXPORT_SYMBOL_GPL(dax_dedupe_file_range_compare); No need for the export. > +EXPORT_SYMBOL(dax_remap_file_range_prep); EXPORT_SYMBOL_GPL, please. Attached is a totally untested patch that just has two levels of iterations instead of the new iter2 helper: diff --git a/fs/dax.c b/fs/dax.c index 0e0536765a7efc..2b65471785290d 100644 --- a/fs/dax.c +++ b/fs/dax.c @@ -1885,6 +1885,7 @@ static loff_t dax_range_compare_iter(struct iomap_iter *it_src, loff_t len = min(smap->length, dmap->length); void *saddr, *daddr; int ret; + int id; if (smap->type == IOMAP_HOLE && dmap->type == IOMAP_HOLE) { *same = true; @@ -1896,47 +1897,56 @@ static loff_t dax_range_compare_iter(struct iomap_iter *it_src, return 0; } + id = dax_read_lock(); ret = dax_iomap_direct_access(smap, pos1, ALIGN(pos1 + len, PAGE_SIZE), &saddr, NULL); if (ret < 0) - return -EIO; + goto out_unlock; ret = dax_iomap_direct_access(dmap, pos2, ALIGN(pos2 + len, PAGE_SIZE), &daddr, NULL); if (ret < 0) - return -EIO; + goto out_unlock; *same = !memcmp(saddr, daddr, len); if (!*same) - return 0; + len = 0; + dax_read_unlock(id); return len; + +out_unlock: + dax_read_unlock(id); + return -EIO; } int dax_dedupe_file_range_compare(struct inode *src, loff_t srcoff, - struct inode *dest, loff_t destoff, loff_t len, bool *same, + struct inode *dst, loff_t dstoff, loff_t len, bool *same, const struct iomap_ops *ops) { - struct iomap_iter it_src = { + struct iomap_iter src_iter = { .inode = src, .pos = srcoff, .len = len, }; - struct iomap_iter it_dest = { - .inode = dest, - .pos = destoff, + struct iomap_iter dst_iter = { + .inode = dst, + .pos = dstoff, .len = len, }; - int id, ret; + int ret; - id = dax_read_lock(); - while ((ret = iomap_iter2(&it_src, &it_dest, ops)) > 0) { - it_src.processed = it_dest.processed = - dax_range_compare_iter(&it_src, &it_dest, same); + while ((ret = iomap_iter(&src_iter, ops)) > 0) { + while ((ret = iomap_iter(&dst_iter, ops)) > 0) { + dst_iter.processed = dax_range_compare_iter(&src_iter, + &dst_iter, same); + if (dst_iter.processed > 0) + src_iter.processed += dst_iter.processed; + else if (!src_iter.processed) + src_iter.processed = dst_iter.processed; + } } - dax_read_unlock(id); return ret; } -EXPORT_SYMBOL_GPL(dax_dedupe_file_range_compare); int dax_remap_file_range_prep(struct file *file_in, loff_t pos_in, struct file *file_out, loff_t pos_out, @@ -1946,4 +1956,4 @@ int dax_remap_file_range_prep(struct file *file_in, loff_t pos_in, return __generic_remap_file_range_prep(file_in, pos_in, file_out, pos_out, len, remap_flags, ops); } -EXPORT_SYMBOL(dax_remap_file_range_prep); +EXPORT_SYMBOL_GPL(dax_remap_file_range_prep);