From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id A39EF3CF68E for ; Wed, 4 Mar 2026 18:01:11 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772647271; cv=none; b=eOm6bKU/XW8xaPJoicbHRoknejUOd3hkZ72s9G/SeaKfnisT0bl6LNcGbiEWZS4Y4tCPZBBjXFAlw5KUnULbtD7IN1e6x7hn9RJCwaKF1gaft62W/dDMYbL9vz1wfCQAXCKy63zpKqW3WBBwD7NQT0WDYMwT4DldtSshxluuiVM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772647271; c=relaxed/simple; bh=+DW811hj8lmN7Dm8AazKPS9qkr6D1uhFnfjwl1co1c4=; h=Message-ID:Subject:From:To:Cc:Date:In-Reply-To:References: Content-Type:MIME-Version; b=MmkmiAZnmIkvuHSphIJTxKlHReHfpfZ6SH0866F/qlIs8m14Xn9NeJTPF5o8o65gVj9TC4AZbCu5Og65ME88i6K7d0FbzSH/qS/0R5dF0Kc/+ISqWU+ZHip2aBym1fPrADqNEMugCDcZB3W/j00OFvifKlW/7X00xUD4UGWJUyg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=KOnNeqw2; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="KOnNeqw2" Received: by smtp.kernel.org (Postfix) with ESMTPSA id CE215C4CEF7; Wed, 4 Mar 2026 18:01:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1772647271; bh=+DW811hj8lmN7Dm8AazKPS9qkr6D1uhFnfjwl1co1c4=; h=Subject:From:To:Cc:Date:In-Reply-To:References:From; b=KOnNeqw23humRb0lq32UZ45DK6mf9O1Bui+PSpVYYTbNBonJ90HEn11pxoo0HfXjd UzNT2r3s07aWm25A/C1FKXg/w62Ibjjx21Ki0GyLs1VbvSJpwcXq9LmmHYLbjiTIw9 gNYof7jiOwd9twsMnsYp4MSxUqW6/O/gESchngP3rvUhwfA1ZFogQSub+W1zVAF21W ejFS3vB7atTkRn8Nq6Kig975lFYygBxtloMMKhuA9J/Vo/srEa2NT/OVp9XPgSpnfw CJtUzV9y9NXPmFUc3c7Zv3tvWZHrdH2QWCnqhVw7iJ+sE5AsAUbLXS17KUL00C1jV3 chpuh+LCkL6jA== Message-ID: <5537e04bd752035b8e29bb4eee8e36c873c55465.camel@kernel.org> Subject: Re: [PATCH v3 00/12] vfs: change inode->i_ino from unsigned long to u64 From: Jeff Layton To: Woody Suwalski , LKML Cc: Pavel Machek Date: Wed, 04 Mar 2026 13:01:08 -0500 In-Reply-To: References: <20260304-iino-u64-v3-0-2257ad83d372@kernel.org> Autocrypt: addr=jlayton@kernel.org; prefer-encrypt=mutual; keydata=mQINBE6V0TwBEADXhJg7s8wFDwBMEvn0qyhAnzFLTOCHooMZyx7XO7dAiIhDSi7G1NPxw n8jdFUQMCR/GlpozMFlSFiZXiObE7sef9rTtM68ukUyZM4pJ9l0KjQNgDJ6Fr342Htkjxu/kFV1Wv egyjnSsFt7EGoDjdKqr1TS9syJYFjagYtvWk/UfHlW09X+jOh4vYtfX7iYSx/NfqV3W1D7EDi0PqV T2h6v8i8YqsATFPwO4nuiTmL6I40ZofxVd+9wdRI4Db8yUNA4ZSP2nqLcLtFjClYRBoJvRWvsv4lm 0OX6MYPtv76hka8lW4mnRmZqqx3UtfHX/hF/zH24Gj7A6sYKYLCU3YrI2Ogiu7/ksKcl7goQjpvtV 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change into the same patch. This results in a giant 600+ line patc= h > > at the end of the series, but it does remain bisectable. Because the > > patchset was reorganized (again) some of the R-b's and A-b's have been > > dropped. > >=20 > > The entire pile is in the "iino-u64" branch of my tree, if anyone is > > interested in testing this. > >=20 > > https://git.kernel.org/pub/scm/linux/kernel/git/jlayton/linux.git/ > >=20 > > Original cover letter follows: > >=20 > > ----------------------8<----------------------- > >=20 > > Christian said [1] to "just do it" when I proposed this, so here we are= ! > >=20 > > For historical reasons, the inode->i_ino field is an unsigned long, > > which means that it's 32 bits on 32 bit architectures. This has caused = a > > number of filesystems to implement hacks to hash a 64-bit identifier > > into a 32-bit field, and deprives us of a universal identifier field fo= r > > an inode. > >=20 > > This patchset changes the inode->i_ino field from an unsigned long to a > > u64. This shouldn't make any material difference on 64-bit hosts, but > > 32-bit hosts will see struct inode grow by at least 4 bytes. This could > > have effects on slabcache sizes and field alignment. > >=20 > > The bulk of the changes are to format strings and tracepoints, since th= e > > kernel itself doesn't care that much about the i_ino field. The first > > patch changes some vfs function arguments, so check that one out > > carefully. > >=20 > > With this change, we may be able to shrink some inode structures. For > > instance, struct nfs_inode has a fileid field that holds the 64-bit > > inode number. With this set of changes, that field could be eliminated. > > I'd rather leave that sort of cleanups for later just to keep this > > simple. > >=20 > > Much of this set was generated by LLM, but I attributed it to myself > > since I consider this to be in the "menial tasks" category of LLM usage= . > >=20 > > [1]: https://lore.kernel.org/linux-fsdevel/20260219-portrait-winkt-9590= 70cee42f@brauner/ > >=20 > > Signed-off-by: Jeff Layton > >=20 > Jeff, would you be able to "guestimate" how much extra memory=20 > requirement will it impose on 32-bit architectures? Probably nothing=20 > critical, but good to know :-) >=20 > Thanks, Woody It's hard to say since inode counts can vary widely depending on workload, memory sizing and tuning: If you have a particular machine in mind, you can look at the first column in /proc/sys/fs/inode-state to get a current count of allocated inodes on your system. Multiply that by 4 bytes and you get a best case for the memory increase. The real increase might be worse however -- this can have slabcache alignment effects (and different filesystems have different inode sizes). We may end up being able to mitigate this to some degree however. For instance, nfs (like many filesystems) carries a separate "fileid" field in struct nfs_inode. That could now be dropped in favor of i_ino since we always know it's a u64. This set doesn't go that far because I want to keep this changeset as small as possible, but there is a lot of that sort of low-hanging cleanup that should be possible after this set goes in. --=20 Jeff Layton