From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp-out2.suse.de (smtp-out2.suse.de [195.135.223.131]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 388FE158DC8 for ; Wed, 3 Apr 2024 23:42:15 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=195.135.223.131 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1712187738; cv=none; b=mkn7qb89R+eztA8IYoDVOL0ebqqmxCKZEUncPQu73OAYi4zu2Y5mndLtXxCJNlCm+xrn131kzYEbh4NuosSHgiUuaIBL1T2hj9/Zt0AsbCj3uEuLW5UwAZL3cFypL5p1M3FTcNip73aj9X4Hd1Q3FHiJetfDKCcKXoMAAvaAohw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1712187738; c=relaxed/simple; bh=ZW9Im7EMyv5k+6y70B0oYKklpeI6fxnQoTOHj4jBCwk=; h=From:To:Subject:Date:Message-ID:MIME-Version; b=W9h06DghAO3Zq3FrATtBOp7Nd+ckwlLecY5fTTQuJ9u6dLd0nEbx/C1kovaXW+kJCBA7A02Skvd9oU6gFNVqTQ+nWhqAWvLRYsuE0WPHBcAAaTan9pOyB+UNM6oDT13JqbaKSvjtMa0X/D66SsfPeKZOnbFjhZppP83irXmrtNk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=suse.com; spf=pass smtp.mailfrom=suse.com; dkim=pass (1024-bit key) header.d=suse.com header.i=@suse.com header.b=W3XocgXd; arc=none smtp.client-ip=195.135.223.131 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=suse.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=suse.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=suse.com header.i=@suse.com header.b="W3XocgXd" Received: from imap2.dmz-prg2.suse.org (imap2.dmz-prg2.suse.org [10.150.64.98]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by smtp-out2.suse.de (Postfix) with ESMTPS id 50C555D2E8 for ; Wed, 3 Apr 2024 23:42:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1712187733; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc: mime-version:mime-version: content-transfer-encoding:content-transfer-encoding; bh=B3IY2uK0mUNrjqEkXJYNz2af+fATC0x7sneCSyvXXxM=; b=W3XocgXdnf9AoykCKx4ojYJPVeGYggT7SuBOzcAl0tE59CkOeB2kJjbeRyuwNbLY8Qfcsj EqIU+zPNdX/pOCoeMlR13r6/THYYmk1w+/lVUwRRZKJgo/v5DSIKTZHwp5F+rhg/yxTA+w zAdXR4T68Az1Sy6d9DMmTKACWK/w2LE= Authentication-Results: smtp-out2.suse.de; none Received: from imap2.dmz-prg2.suse.org (localhost [127.0.0.1]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by imap2.dmz-prg2.suse.org (Postfix) with ESMTPS id 81F8C1331E for ; Wed, 3 Apr 2024 23:42:12 +0000 (UTC) Received: from dovecot-director2.suse.de ([2a07:de40:b281:106:10:150:64:167]) by imap2.dmz-prg2.suse.org with ESMTPSA id 3dG4EFTpDWalfQAAn2gu4w (envelope-from ) for ; Wed, 03 Apr 2024 23:42:12 +0000 From: Qu Wenruo To: linux-btrfs@vger.kernel.org Subject: [PATCH v2 0/4] btrfs: more explaination on extent_map members Date: Thu, 4 Apr 2024 10:11:57 +1030 Message-ID: X-Mailer: git-send-email 2.44.0 Precedence: bulk X-Mailing-List: linux-btrfs@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Spamd-Result: default: False [-1.80 / 50.00]; BAYES_HAM(-3.00)[100.00%]; MID_CONTAINS_FROM(1.00)[]; R_MISSING_CHARSET(0.50)[]; NEURAL_HAM_SHORT(-0.20)[-1.000]; MIME_GOOD(-0.10)[text/plain]; RCPT_COUNT_ONE(0.00)[1]; ARC_NA(0.00)[]; DKIM_SIGNED(0.00)[suse.com:s=susede1]; TO_MATCH_ENVRCPT_ALL(0.00)[]; FUZZY_BLOCKED(0.00)[rspamd.com]; RCVD_TLS_ALL(0.00)[]; RCVD_VIA_SMTP_AUTH(0.00)[]; FROM_EQ_ENVFROM(0.00)[]; FROM_HAS_DN(0.00)[]; MIME_TRACE(0.00)[0:+]; RCVD_COUNT_TWO(0.00)[2]; PREVIOUSLY_DELIVERED(0.00)[linux-btrfs@vger.kernel.org]; TO_DN_NONE(0.00)[]; DBL_BLOCKED_OPENRESOLVER(0.00)[imap2.dmz-prg2.suse.org:rdns,imap2.dmz-prg2.suse.org:helo] X-Spam-Score: -1.80 X-Spam-Level: X-Spam-Flag: NO [REPO] https://github.com/adam900710/linux.git/ em_cleanup [CHANGELOG] v2: - Add Filipe's cleanup on mod_start/mod_len These two members are no longer utilized, saving me quite some time on digging into their usage. - Update the comments of the extent_map structure To make them more readable and less confusing. - Further cleanup for inline extent_map reading - A new patch to do extra sanity checks for create_io_em() Firstly pure NOCOW writes should not call create_io_em(), secondly with the new knowledge of extent_map, it's easier to do extra sanity checks for the already pretty long parameter list. Btrfs uses extent_map to represent a in-memory file extent. There are severam members that are 1:1 mappe in on-disk file extent items and extent maps: - extent_map::start == key.offset - extent_map::len == file_extent_num_bytes - extent_map::ram_bytes == file_extent_ram_bytes But that's all, the remaining are pretty different: - Use block_start to indicate holes/inline extents Meanwhile btrfs on-disk file extent items go with a dedicated type for inline extents, and disk_bytenr 0 for holes. - Extra members for fsync optimization I'm still not 100% sure how mod_start and mod_len really works though. - Weird block_start/orig_block_len/orig_start In theory we can directly go with the same file_extent_disk_bytenr, file_extent_disk_num_bytes and file_extent_offset to calculate the remaining members (block_start/orig_start/orig_block_len/block_len). But for whatever reason, we didn't go that path and have a hell of weird and inconsistent calculation for them. I do not have the confidence to handle the mess yet, but as the first step, I would add comments for those members mostly according to btrfs_extent_item_to_extent_map(), and hopefully we can improve the situation in not-far-away future. Filipe Manana (1): btrfs: remove not needed mod_start and mod_len from struct extent_map Qu Wenruo (3): btrfs: add extra comments on extent_map members btrfs: simplify the inline extent map creation btrfs: add extra sanity checks for create_io_em() fs/btrfs/extent_map.c | 18 ----------- fs/btrfs/extent_map.h | 58 ++++++++++++++++++++++++++++++++---- fs/btrfs/file-item.c | 15 +++++----- fs/btrfs/inode.c | 44 ++++++++++++++++++++++++--- fs/btrfs/tree-log.c | 4 +-- include/trace/events/btrfs.h | 3 +- 6 files changed, 104 insertions(+), 38 deletions(-) -- 2.44.0