linux-ext4 - Re: [PATCH] ext4: fix dir

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Message-ID: <20170722164945.77z7bmk3rxbfceym@thunk.org>
Date:   Sat, 22 Jul 2017 12:49:45 -0400
From:   Theodore Ts'o <tytso@....edu>
To:     Damien Guibouret <damien.guibouret@...tition-saving.com>
Cc:     Andreas Dilger <adilger@...ger.ca>, linux-ext4@...r.kernel.org,
        eggert@...ucla.edu
Subject: Re: [PATCH] ext4: fix dir_nlink behaviour

On Sat, Jul 22, 2017 at 03:38:41PM +0200, Damien Guibouret wrote:
> 
> If you look at vfs layer, vfs_mkdir does the check against max_links with >=
> and so if you reach the value, you will never be able to create a new
> directory even if nlink feature is present. Actually it is not a problem
> because ext4 does not set the s_max_links value in vfs (do not know why as
> ext2 set it perhaps because there is no limit if nlink is set?), but it
> could be some latent bug if someday somebody thinks it could be a good idea
> to set it.

We can't set s_max_links precisely because of the dir_nlinks feature.
So the fact that it is not set today is deliberate, and if someone
thought it was good idea, I and the other ext4 developers would NAK
it.

						- Ted