linux-ext4 - Re: [PATCH] mke2fs: avoid inode number error with large FS

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Message-ID: <20180212163105.bcejqb63rksudyz3@rh_laptop>
Date:   Mon, 12 Feb 2018 17:31:05 +0100
From:   Lukas Czerner <lczerner@...hat.com>
To:     sandeen@...hat.com
Cc:     Artem Blagodarenko <artem.blagodarenko@...il.com>,
        linux-ext4@...r.kernel.org, adilger.kernel@...ger.ca,
        Alexey Lyashkov <alexey.lyashkov@...il.com>
Subject: Re: [PATCH] mke2fs: avoid inode number error with large FS

On Mon, Feb 12, 2018 at 10:06:57AM -0600, Eric Sandeen wrote:
> 
> 
> On 2/12/18 9:45 AM, Lukas Czerner wrote:
> > On Mon, Feb 12, 2018 at 02:14:19PM +0300, Artem Blagodarenko wrote:
> >> From: Alexey Lyashkov <alexey.lyashkov@...il.com>
> >>
> >> Sometimes during system deployment customers are faced with system
> >> formating problem for given inodes/bytes rate. User need to recalucate
> >> this rate and start formating again.
> >>
> >> This patch adds code that limit inodes count instead of error return,
> >> to use all inodes in the filesystem.
> > 
> > Hi,
> > 
> > in this case then you do not have byte-per-inode ratio you've
> > specified. So why to specify it in the first place ?
> > 
> > Maybe I am missing something but I would think that if you specify -i
> > then you know what you want and if it's not possible then I would not
> > expect the mke2fs to just succeed regardless. I guess it's confusing.
> 
> I agree that fixing up incorrect/impossible format specifications and
> continuing is not preferable; it really makes the behavior matrix complex
> when some incorrect options are fixed on the fly, while others fail.
> 
> And worse, this creates a new "default" behavior which comes into play
> only when specific incorrect mkfs options are explicitly provided.
> 
> When an admin stops using mkfs defaults and starts manually specifying
> geometry, the onus is on /them/ to specify options which are valid.
> 
> > Also the man page says:
> > 
> > "This value generally shouldn't be smaller than the blocksize of the
> > filesystem, since in that case more inodes would be made than can ever
> > be used."
> > 
> > But in your case you're using "-i 1024" on what I assume is a 4k bs file
> > system ?
> 
> Right, can you offer a concrete example of the commandline you're trying
> to fix?
> 
> If it's "-i 1024" on a 4k filesystem, that's simply broken and /should/
> be rejected.  If the error message is not clear, perhaps that's the best
> place to focus these efforts.

I think that inline data actually changes that ? However if that's the
case then we need to change the documentation. But it still does not
mean we want to "autocorrect" spcified values.

-Lukas

> 
> Thanks,
> -Eric