From: Andreas Dilger Subject: Re: [PATCH v1 00/30] Ext4 snapshots Date: Tue, 21 Jun 2011 09:45:57 -0600 Message-ID: <0A68B7C0-C7DD-456C-BC52-A169C5521933@dilger.ca> References: <1307459283-22130-1-git-send-email-amir73il@users.sourceforge.net> Mime-Version: 1.0 (iPhone Mail 8J2) Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 8BIT Cc: Theodore Tso , Ext4 Developers List To: "Amir G." Return-path: Received: from shawmail.shawcable.com ([64.59.128.220]:56415 "EHLO mail.shawcable.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752717Ab1FUPpk convert rfc822-to-8bit (ORCPT ); Tue, 21 Jun 2011 11:45:40 -0400 In-Reply-To: Sender: linux-ext4-owner@vger.kernel.org List-ID: On 2011-06-21, at 5:06 AM, "Amir G." wrote: > On Tue, Jun 7, 2011 at 6:07 PM, wrote: >> >> I am resending the snapshots patch series as per Lukas's request. >> This time, the snapshot*.c files have not been omitted, as in >> the previous posting. >> >> The series is still based on ext4 dev branch sometime in the preparation >> for 3.0 merge window. It was not yet rebased on 3.0-rc1, so punch holes >> changes have not been addressed yet. >> >> As always, I advocate online review of the patches at: >> https://github.com/amir73il/ext4-snapshots/commits/for-ext4-v1 >> but if you insist on doing it the old way, I won't complain. >> >> > > To answer your question about possible diet to snapshot patches, > following are some diffstat on groups of patches (by functionality). > The diffsstat includes only ext4 core file (excluding new snapshot* files). > > As you can see, removing the shrink/merge functionality for multiple > snapshots, will remove the need for exclude bitmap and reduce the changes > to core files by ~300 insertions. > > There is some advantage of not having to add the exclude bitmap to existing > fs, but I think the win is not so big, assuming that we will want to have the > shrink/merge functionality eventually. Wouldn't that also mean if shrink/merge are added later it needs another feature flag and added complexity due to another row in the feature test matrix? > >> [PATCH v1 01/36] ext4: EXT4 snapshots (Experimental) >> [PATCH v1 02/36] ext4: snapshot debugging support > > Generic stuff. > > 15 files changed, 122 insertions(+), 1 deletions(-) > >> [PATCH v1 03/36] ext4: snapshot hooks - inside JBD hooks >> [PATCH v1 04/36] ext4: snapshot hooks - block bitmap access >> [PATCH v1 05/36] ext4: snapshot hooks - delete blocks >> [PATCH v1 06/36] ext4: snapshot hooks - move data blocks >> [PATCH v1 07/36] ext4: snapshot hooks - direct I/O >> [PATCH v1 08/36] ext4: snapshot hooks - move extent file data blocks > > Most of the code in this group handles MOW. > > 7 files changed, 550 insertions(+), 68 deletions(-) > >> [PATCH v1 09/36] ext4: snapshot file >> [PATCH v1 10/36] ext4: snapshot file - read through to block device >> [PATCH v1 11/36] ext4: snapshot file - permissions >> [PATCH v1 12/36] ext4: snapshot file - store on disk >> [PATCH v1 13/36] ext4: snapshot file - increase maximum file size limit to 16TB > > Implementation of special snapshot file. > > 7 files changed, 220 insertions(+), 14 deletions(-) > >> [PATCH v1 14/36] ext4: snapshot block operations >> [PATCH v1 15/36] ext4: snapshot block operation - copy blocks to snapshot >> [PATCH v1 16/36] ext4: snapshot block operation - move blocks to snapshot >> [PATCH v1 17/36] ext4: snapshot block operation - copy block bitmap to snapshot > > Copy/move to snapshot file operations. > > 5 files changed, 126 insertions(+), 24 deletions(-) > >> [PATCH v1 18/36] ext4: snapshot control >> [PATCH v1 19/36] ext4: snapshot control - init new snapshot >> [PATCH v1 20/36] ext4: snapshot control - fix new snapshot >> [PATCH v1 21/36] ext4: snapshot control - reserve disk space for snapshot > > Mostly new code in ioctl.c. > > 6 files changed, 171 insertions(+), 3 deletions(-) > >> [PATCH v1 22/36] ext4: snapshot journaled - increase transaction credits >> [PATCH v1 23/36] ext4: snapshot journaled - implement journal_release_buffer() >> [PATCH v1 24/36] ext4: snapshot journaled - bypass to save credits >> [PATCH v1 25/36] ext4: snapshot journaled - cache last COW tid in journal_head > > Helper functions to handle extra COW credits. > > 7 files changed, 284 insertions(+), 31 deletions(-) > >> [PATCH v1 26/36] ext4: snapshot journaled - trace COW/buffer credits > > Trace/debug for extra COW credits. > > 3 files changed, 108 insertions(+), 0 deletions(-) > >> [PATCH v1 27/36] ext4: snapshot list support >> [PATCH v1 28/36] ext4: snapshot list - read through to previous snapshot > > Not much to gain from dropping snapshot list support... > > 2 files changed, 2 insertions(+), 0 deletions(-) > >> [PATCH v1 29/36] ext4: snapshot race conditions - concurrent COW bitmap operations >> [PATCH v1 30/36] ext4: snapshot race conditions - concurrent COW operations >> [PATCH v1 31/36] ext4: snapshot race conditions - tracked reads > > We must handle race conditions. > > 2 files changed, 32 insertions(+), 0 deletions(-) > >> [PATCH v1 32/36] ext4: snapshot exclude - the exclude bitmap > > We do not need the exclude bitmap if we do not shrink/merge snapshots. > > 5 files changed, 226 insertions(+), 3 deletions(-) > >> [PATCH v1 33/36] ext4: snapshot cleanup >> [PATCH v1 34/36] ext4: snapshot cleanup - shrink deleted snapshots >> [PATCH v1 35/36] ext4: snapshot cleanup - merge shrunk snapshots > > We could support multiple snapshots without shrinking/merging deleted snapshot, > but that means that only disk space of oldest snapshot is reclaimed on delete. > > 2 files changed, 74 insertions(+), 22 deletions(-) > >> [PATCH v1 36/36] ext4: snapshot rocompat - enable rw mount >> >> fs/ext4/Kconfig | 11 + >> fs/ext4/Makefile | 3 + >> fs/ext4/balloc.c | 132 +++ >> fs/ext4/ext4.h | 188 ++++- >> fs/ext4/ext4_jbd2.c | 162 ++++- >> fs/ext4/ext4_jbd2.h | 266 ++++++- >> fs/ext4/extents.c | 157 ++++- >> fs/ext4/file.c | 11 +- >> fs/ext4/ialloc.c | 19 +- >> fs/ext4/inode.c | 668 +++++++++++++-- >> fs/ext4/ioctl.c | 120 +++ >> fs/ext4/mballoc.c | 161 ++++- >> fs/ext4/move_extent.c | 3 +- >> fs/ext4/namei.c | 9 + >> fs/ext4/resize.c | 19 +- >> fs/ext4/snapshot.c | 1000 ++++++++++++++++++++++ >> fs/ext4/snapshot.h | 690 ++++++++++++++++ >> fs/ext4/snapshot_buffer.c | 393 +++++++++ >> fs/ext4/snapshot_ctl.c | 2002 +++++++++++++++++++++++++++++++++++++++++++++ >> fs/ext4/snapshot_debug.c | 107 +++ >> fs/ext4/snapshot_debug.h | 105 +++ >> fs/ext4/snapshot_inode.c | 960 ++++++++++++++++++++++ >> fs/ext4/super.c | 157 ++++- >> fs/ext4/xattr.c | 4 +- >> 24 files changed, 7182 insertions(+), 165 deletions(-) >> >> > -- > To unsubscribe from this list: send the line "unsubscribe linux-ext4" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html