From: Al Viro <viro@ZenIV.linux.org.uk>
To: Dan Ehrenberg <dehrenberg@chromium.org>
Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
gwendal@chromium.org, ezequiel@vanguardiasur.com.ar
Subject: Re: [RFC PATCH] vfs: Use 12:20 bit major:minor in stat everywhere
Date: Wed, 4 Mar 2015 00:53:47 +0000 [thread overview]
Message-ID: <20150304005347.GU29656@ZenIV.linux.org.uk> (raw)
In-Reply-To: <1425429420-13142-1-git-send-email-dehrenberg@chromium.org>
On Tue, Mar 03, 2015 at 04:37:00PM -0800, Dan Ehrenberg wrote:
> Previously, stat on 32-bit platforms used old-style encoding and
> validation of major-minor pairs, with 8:8 bits. However, dev_t is
> 32-bits on these platforms, and coreutils seems to be treating the
> values as 12:20 new-style values. The only reason to use the old
> version is in the implementation of a legacy filesystem format which
> only has 16 bits of space. Communicating a 12:20 value to userspace
> when sizeof dev_t == 4 can be done on either a 32-bit or 64-bit
> platform.
>
> This patch removes the artificial restriction in major:minor size.
> The only backwards incompatibility which results is sometimes stat
> succeeds if -EOVERFLOW would be returned otherwise. The legacy
> old-style stat call is retained as-is.
Umm... You do realize that coreutils are _very_ far from being the only
userland programs handling the data returned by stat(2), right?
What's to guarantee that your ABI change won't break any of those?
next prev parent reply other threads:[~2015-03-04 0:53 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-03-04 0:37 [RFC PATCH] vfs: Use 12:20 bit major:minor in stat everywhere Dan Ehrenberg
2015-03-04 0:53 ` Al Viro [this message]
2015-03-04 1:10 ` Daniel Ehrenberg
2015-03-04 1:22 ` Al Viro
2015-03-04 1:37 ` Gwendal Grignou
2015-03-04 1:47 ` Al Viro
2015-03-04 7:26 ` Gwendal Grignou
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20150304005347.GU29656@ZenIV.linux.org.uk \
--to=viro@zeniv.linux.org.uk \
--cc=dehrenberg@chromium.org \
--cc=ezequiel@vanguardiasur.com.ar \
--cc=gwendal@chromium.org \
--cc=linux-fsdevel@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.