From: Artem Bityutskiy Subject: [PATCHv7 0/5] ext4: stop using write_supers and s_dirt Date: Wed, 11 Jul 2012 16:46:39 +0300 Message-ID: <1342014404-14834-1-git-send-email-dedekind1@gmail.com> Cc: Linux FS Maling List , Linux Kernel Maling List , Ext4 Mailing List To: Theodore Tso , Jan Kara Return-path: Sender: linux-kernel-owner@vger.kernel.org List-Id: linux-ext4.vger.kernel.org This patch-set makes ext4 file-system stop using the VFS '->write_supers()' call-back and the '->s_dirt' superblock field because I plan to remove them once all users are gone. What we do in this patch-set is we notice that ext4 does not really needed the 'write_super()' functionality and we can remove it. Instead, we simply mark the superblock buffer as dirty directly, rather than postponing this till the next 'sync_supers()' kernel thread wake-up. Most of the ext4 changes were done or suggested by Jan Kara - thanks Jan! V7 is identical to v6, but I've added Jan's "Reviewed-by" and removed my worries about slowing down the deletion path - they were false, apologies. So only the commit messages changed. Tested with xfstests (both journalled and non-journalled ext4 modes). fs/ext4/ext4.h | 9 --------- fs/ext4/ext4_jbd2.c | 8 +++----- fs/ext4/ext4_jbd2.h | 7 ++----- fs/ext4/file.c | 14 +++++++++++++- fs/ext4/ialloc.c | 2 -- fs/ext4/inode.c | 2 +- fs/ext4/mballoc.c | 2 -- fs/ext4/namei.c | 4 ++-- fs/ext4/resize.c | 2 +- fs/ext4/super.c | 12 +----------- 10 files changed, 23 insertions(+), 39 deletions(-) Reminder ======== The goal is to get rid of the 'sync_supers()' kernel thread. This kernel thread wakes up every 5 seconds (by default) and calls '->write_super()' for all mounted file-systems. And the bad thing is that this is done even if all the superblocks are clean. Moreover, many file-systems do not even need this and they do not even register the '->write_super()' method at all (e.g., btrfs). So 'sync_supers()' mostly just generates useless wake-ups and wastes power. I am trying to make all file-systems independent of '->write_super()' and plan to remove 'sync_supers()' and '->write_super()' completely once there are no more users. Overall status ============== 1. ext4: patches submitted, https://lkml.org/lkml/2012/7/10/195 2. exofs: patch submitted, https://lkml.org/lkml/2012/6/4/211 3. sysv: patches submitted, http://lkml.org/lkml/2012/7/3/250 4. udf: patch submitted, sits in Jan Kara's tree: https://lkml.org/lkml/2012/6/4/233 git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs for_testing 5. affs: patches submitted, sit in Al Viro's tree: https://lkml.org/lkml/2012/6/6/400 git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs for-next 6. hfs: patches submitted, sit Andrew Morton's tree http://lkml.org/lkml/2012/6/12/82 7. hfsplus: patches submitted, sit in Andrew Morton's tree: https://lkml.org/lkml/2012/6/13/195 8. ext2: done, see commit f72cf5e223a28d3b3ea7dc9e40464fd534e359e8 9. vfat: done, see commit 78491189ddb6d84d4a4abae992ed891a236d0263 10. jffs2: done, see commit 208b14e507c00ff7f108e1a388dd3d8cc805a443 11. reiserfs: done, see commit 033369d1af1264abc23bea2e174aa47cdd212f6f TODO: ufs Thanks, Artem.