From mboxrd@z Thu Jan  1 00:00:00 1970
From: Jeff Layton <jlayton@kernel.org>
Subject: Re: [PATCH 87/87] fs: move i_blocks up a few places in struct inode
Date: Thu, 28 Sep 2023 08:01:50 -0400
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To: Amir Goldstein <amir73il@gmail.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>, Christian Brauner <brauner@kernel.org>, Linus Torvalds <torvalds@linux-foundation.org>, David Sterba <dsterba@suse.cz>, Theodore Ts'o <tytso@mit.edu>, Eric Biederman <ebiederm@xmission.com>, Kees Cook <keescook@chromium.org>, Jeremy Kerr <jk@ozlabs.org>, Arnd Bergmann <arnd@arndb.de>, Michael Ellerman <mpe@ellerman.id.au>, Nicholas Piggin <npiggin@gmail.com>, Christophe Leroy <christophe.leroy@csgroup.eu>, Heiko Carstens <hca@linux.ibm.com>, Vasily Gorbik <gor@linux.ibm.com>, Alexander Gordeev <agordeev@linux.ibm.com>, Christian Borntraeger <borntraeger@linux.ibm.com>, Sven Schnelle <svens@linux.ibm.com>, Greg Kroah-Hartman <gregkh@linuxfoundation.org>, Arve =?ISO-8859-1?Q?Hj=F8nnev=E5g?= <arve@android.com>, Todd Kjos <tkjos@android.com>, Martijn Coenen <maco@android.com>, Joel Fernandes <joel@joelfernandes.org>, Carlos Llamas <>

On Thu, 2023-09-28 at 14:35 +0300, Amir Goldstein wrote:
> On Thu, Sep 28, 2023 at 2:06=E2=80=AFPM Jeff Layton <jlayton@kernel.org> =
wrote:
> >=20
> > The recent change to use discrete integers instead of struct timespec64
> > in struct inode shaved 8 bytes off of it, but it also moves the i_lock
> > into the previous cacheline, away from the fields that it protects.
> >=20
> > Move i_blocks up above the i_lock, which moves the new 4 byte hole to
> > just after the timestamps, without changing the size of the structure.
> >=20
>=20
> Instead of creating an implicit hole, can you please move i_generation
> to fill the 4 bytes hole.
>=20
> It makes sense in the same cache line with i_ino and I could
> use the vacant 4 bytes hole above i_fsnotify_mask to expand the
> mask to 64bit (the 32bit event mask space is running out).
>=20
> Thanks,
> Amir.
>=20

Sounds like a plan. Resulting struct inode size is the same (616 bytes
with my kdevops kconfig). BTW: all of these changes are in my "amtime"
branch if anyone wants to pull them down.
--
Jeff Layton <jlayton@kernel.org>