From patchwork Fri Oct 14 07:17:09 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Qu Wenruo X-Patchwork-Id: 13006712 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5DEE9C433FE for ; Fri, 14 Oct 2022 07:17:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229701AbiJNHRi (ORCPT ); Fri, 14 Oct 2022 03:17:38 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34312 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229554AbiJNHRf (ORCPT ); Fri, 14 Oct 2022 03:17:35 -0400 Received: from smtp-out2.suse.de (smtp-out2.suse.de [195.135.220.29]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3985EC6955 for ; Fri, 14 Oct 2022 00:17:33 -0700 (PDT) Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by smtp-out2.suse.de (Postfix) with ESMTPS id 922461F385 for ; Fri, 14 Oct 2022 07:17:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1665731852; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc: mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=hug+dIeeUptzXKXWLSCXA+hEhBZuU+xQN6yNLCsNJKM=; b=Q6SLxZ/ojHiGPh1YbLVj9ie/N6WnuNYwlFtVj0D+VsbFOyAY9DXiM/7G7U+KWAVQ8g8wt+ riSN41a9hMluU6wN+1xsdctHZ1PmRE4D5uVG1Q6fsE5MewrQ2cw2dR/yMYrwK2I69Nl7UE IVch8+1L3jyQAYJU3+LbyIpNdxWdOSQ= Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by imap2.suse-dmz.suse.de (Postfix) with ESMTPS id D4A2B13451 for ; Fri, 14 Oct 2022 07:17:31 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id uD7PJQsNSWOsUwAAMHmgww (envelope-from ) for ; Fri, 14 Oct 2022 07:17:31 +0000 From: Qu Wenruo To: linux-btrfs@vger.kernel.org Subject: [PATCH RFC 1/5] btrfs: refactor btrfs_lookup_csums_range() Date: Fri, 14 Oct 2022 15:17:09 +0800 Message-Id: X-Mailer: git-send-email 2.37.3 In-Reply-To: References: MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org The refactor involves the following parts: - Introduce bytes_to_csum_size() and csum_size_to_bytes() helpers As we have quite some open-coded calculation, some of them are even split into two assignments just to fit 80 chars limit. - Remove the @csum_size parameter from max_ordered_sum_bytes() Csum size can be fetched from @fs_info. And we will use the csum_size_to_bytes() helper anyway. - Add a comment explaining how we had the first search result - Use newly introduced helpers to cleanup btrfs_lookup_csums_range() - Move variables declaration to the minimal scope - Never mix number of sectors with bytes There are several locations doing things like: size = min_t(size_t, csum_end - start, max_ordered_sum_bytes(fs_info)); ... size >>= fs_info->sectorsize_bits Or offset = (start - key.offset) >> fs_info->sectorsize_bits; offset *= csum_size; Make sure those variables can only represent BYTES inside the function, by using the above bytes_to_csum_size() helpers. Signed-off-by: Qu Wenruo --- fs/btrfs/file-item.c | 69 ++++++++++++++++++++++++++++++-------------- 1 file changed, 48 insertions(+), 21 deletions(-) diff --git a/fs/btrfs/file-item.c b/fs/btrfs/file-item.c index 6bb9fa961a6a..8d9c4488d86a 100644 --- a/fs/btrfs/file-item.c +++ b/fs/btrfs/file-item.c @@ -121,12 +121,26 @@ int btrfs_inode_clear_file_extent_range(struct btrfs_inode *inode, u64 start, start + len - 1, EXTENT_DIRTY, NULL); } -static inline u32 max_ordered_sum_bytes(struct btrfs_fs_info *fs_info, - u16 csum_size) +static size_t bytes_to_csum_size(struct btrfs_fs_info *fs_info, u32 bytes) { - u32 ncsums = (PAGE_SIZE - sizeof(struct btrfs_ordered_sum)) / csum_size; + ASSERT(IS_ALIGNED(bytes, fs_info->sectorsize)); - return ncsums * fs_info->sectorsize; + return (bytes >> fs_info->sectorsize_bits) * fs_info->csum_size; +} + +static size_t csum_size_to_bytes(struct btrfs_fs_info *fs_info, u32 csum_size) +{ + ASSERT(IS_ALIGNED(csum_size, fs_info->csum_size)); + + return (csum_size / fs_info->csum_size) << fs_info->sectorsize_bits; +} + +static inline u32 max_ordered_sum_bytes(struct btrfs_fs_info *fs_info) +{ + int max_csum_size = round_down(PAGE_SIZE - sizeof(struct btrfs_ordered_sum), + fs_info->csum_size); + + return csum_size_to_bytes(fs_info, max_csum_size); } /* @@ -135,9 +149,8 @@ static inline u32 max_ordered_sum_bytes(struct btrfs_fs_info *fs_info, */ static int btrfs_ordered_sum_size(struct btrfs_fs_info *fs_info, unsigned long bytes) { - int num_sectors = (int)DIV_ROUND_UP(bytes, fs_info->sectorsize); - - return sizeof(struct btrfs_ordered_sum) + num_sectors * fs_info->csum_size; + return sizeof(struct btrfs_ordered_sum) + + bytes_to_csum_size(fs_info, bytes); } int btrfs_insert_hole_extent(struct btrfs_trans_handle *trans, @@ -521,11 +534,7 @@ int btrfs_lookup_csums_range(struct btrfs_root *root, u64 start, u64 end, struct btrfs_ordered_sum *sums; struct btrfs_csum_item *item; LIST_HEAD(tmplist); - unsigned long offset; int ret; - size_t size; - u64 csum_end; - const u32 csum_size = fs_info->csum_size; ASSERT(IS_ALIGNED(start, fs_info->sectorsize) && IS_ALIGNED(end + 1, fs_info->sectorsize)); @@ -551,16 +560,33 @@ int btrfs_lookup_csums_range(struct btrfs_root *root, u64 start, u64 end, if (ret > 0 && path->slots[0] > 0) { leaf = path->nodes[0]; btrfs_item_key_to_cpu(leaf, &key, path->slots[0] - 1); + + /* + * There are two cases we can hit here for the previous + * csum item. + * + * |<- search range ->| + * |<- csum item ->| + * + * Or + * |<- search range ->| + * |<- csum item ->| + * + * Check if the previous csum item covers the leading part + * of the search range. + * If so we have to start from previous csum item. + */ if (key.objectid == BTRFS_EXTENT_CSUM_OBJECTID && key.type == BTRFS_EXTENT_CSUM_KEY) { - offset = (start - key.offset) >> fs_info->sectorsize_bits; - if (offset * csum_size < + if (bytes_to_csum_size(fs_info, start - key.offset) < btrfs_item_size(leaf, path->slots[0] - 1)) path->slots[0]--; } } while (start <= end) { + u64 csum_end; + leaf = path->nodes[0]; if (path->slots[0] >= btrfs_header_nritems(leaf)) { ret = btrfs_next_leaf(root, path); @@ -580,8 +606,8 @@ int btrfs_lookup_csums_range(struct btrfs_root *root, u64 start, u64 end, if (key.offset > start) start = key.offset; - size = btrfs_item_size(leaf, path->slots[0]); - csum_end = key.offset + (size / csum_size) * fs_info->sectorsize; + csum_end = key.offset + csum_size_to_bytes(fs_info, + btrfs_item_size(leaf, path->slots[0])); if (csum_end <= start) { path->slots[0]++; continue; @@ -591,8 +617,11 @@ int btrfs_lookup_csums_range(struct btrfs_root *root, u64 start, u64 end, item = btrfs_item_ptr(path->nodes[0], path->slots[0], struct btrfs_csum_item); while (start < csum_end) { + unsigned long offset; + size_t size; + size = min_t(size_t, csum_end - start, - max_ordered_sum_bytes(fs_info, csum_size)); + max_ordered_sum_bytes(fs_info)); sums = kzalloc(btrfs_ordered_sum_size(fs_info, size), GFP_NOFS); if (!sums) { @@ -603,16 +632,14 @@ int btrfs_lookup_csums_range(struct btrfs_root *root, u64 start, u64 end, sums->bytenr = start; sums->len = (int)size; - offset = (start - key.offset) >> fs_info->sectorsize_bits; - offset *= csum_size; - size >>= fs_info->sectorsize_bits; + offset = bytes_to_csum_size(fs_info, start - key.offset); read_extent_buffer(path->nodes[0], sums->sums, ((unsigned long)item) + offset, - csum_size * size); + bytes_to_csum_size(fs_info, size)); - start += fs_info->sectorsize * size; + start += size; list_add_tail(&sums->list, &tmplist); } path->slots[0]++;