linux-kernel - Re: [patch] document ext3 a bit better

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Date:	Sat, 10 Jan 2009 00:24:36 +0100 (CET)
From:	Jiri Kosina <jkosina@...e.cz>
To:	Pavel Machek <pavel@...e.cz>,
	Randy Dunlap <randy.dunlap@...cle.com>,
	Jonathan Corbet <corbet@....net>
cc:	Theodore Tso <tytso@....edu>,
	kernel list <linux-kernel@...r.kernel.org>,
	Andrew Morton <akpm@...l.org>, mtk.manpages@...il.com,
	linux-doc@...r.kernel.org,
	Trivial patch monkey <trivial@...nel.org>
Subject: Re: [patch] document ext3 a bit better

On Tue, 6 Jan 2009, Pavel Machek wrote:

> On Mon 2009-01-05 09:57:13, Theodore Tso wrote:
> > On Sun, Jan 04, 2009 at 11:34:33PM +0100, Pavel Machek wrote:
> > > @@ -14,6 +14,11 @@ Options
> > >  When mounting an ext3 filesystem, the following option are accepted:
> > >  (*) == default
> > >  
> > > +ro			Mount filesystem read only. Note that ext3 will replay
> > > +			the journal (and thus write to the partition) even when
> > > +			mounted "read only". "ro, noload" can be used to prevent
> > > +			writes to the filesystem.
> > 
> > I'd sugest "ro,noload" since the spaces screw up the mount options
> > parsing both on the command-line and in /etc/fstab.  So how about:
> > 
> > 	Using the mount options "ro,noload" can be used....
> 
> Too many "using", but yes, fixed, thanks.
> 
> > > @@ -95,6 +102,8 @@ debug			Extra debugging information is s
> > >  errors=remount-ro(*)	Remount the filesystem read-only on an error.
> > >  errors=continue		Keep going on a filesystem error.
> > >  errors=panic		Panic and halt the machine if an error occurs.
> > > +			(Note that default is overriden by superblock
> > > +			setting on most systems).
> > 
> > The default is always specified by the superblock setting.  So users
> > will probably find it easier to understand if we remove the "(*)" and
> > to add the explanatory comment:
> > 
> > 			(These mount options override the errors behavior
> > 			specified in the superblock, which can be configured
> > 			using tune2fs)
> > 
> > Pavel, thanks for working on improving the documentation; with these
> > fixes,
> 
> Thanks!
> 
> ---
> 
> ext3 has quite unexpected semantics or "ro" and defaults are
> not what they are documented to be, due to mkfs override.
> 
> Signed-off-by: Pavel Machek <pavel@...e.cz>
> Signed-off-by: "Theodore Ts'o" <tytso@....edu>
> 
> diff --git a/Documentation/filesystems/ext3.txt b/Documentation/filesystems/ext3.txt
> index 9dd2a3b..49c08bf 100644
> --- a/Documentation/filesystems/ext3.txt
> +++ b/Documentation/filesystems/ext3.txt
> @@ -14,6 +14,11 @@ Options
>  When mounting an ext3 filesystem, the following option are accepted:
>  (*) == default
>  
> +ro			Mount filesystem read only. Note that ext3 will replay
> +			the journal (and thus write to the partition) even when
> +			mounted "read only". Mount options "ro,noload" can be
> +			used to prevent writes to the filesystem.
> +
>  journal=update		Update the ext3 file system's journal to the current
>  			format.
>  
> @@ -27,7 +32,9 @@ journal_dev=devnum	When the external jou
>  			identified through its new major/minor numbers encoded
>  			in devnum.
>  
> -noload			Don't load the journal on mounting.
> +noload			Don't load the journal on mounting. Note that this forces
> +			mount of inconsistent filesystem, which can lead to
> +			various problems.
>  
>  data=journal		All data are committed into the journal prior to being
>  			written into the main file system.
> @@ -92,9 +99,12 @@ nocheck
>  
>  debug			Extra debugging information is sent to syslog.
>  
> -errors=remount-ro(*)	Remount the filesystem read-only on an error.
> +errors=remount-ro	Remount the filesystem read-only on an error.
>  errors=continue		Keep going on a filesystem error.
>  errors=panic		Panic and halt the machine if an error occurs.
> +			(These mount options override the errors behavior
> +			specified in the superblock, which can be 
> +			configured using tune2fs.)			
>  
>  data_err=ignore(*)	Just print an error message if an error occurs
>  			in a file data buffer in ordered mode.
> 

So, documentation guys, are you going to take this patch through the 
Documentation tree (tytso already Signed off on that), or should I take it 
through trivial tree?

Thanks,

-- 
Jiri Kosina
SUSE Labs
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