linux-ext4 - Re: ext4 discard does not apper in /proc/mounts

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Date:	Mon, 09 Jan 2012 21:23:23 +0200
From:	Andrei Popa <andrei.popa@...eo.ro>
To:	Eric Sandeen <sandeen@...hat.com>
Cc:	linux-ext4@...r.kernel.org
Subject: Re: ext4 discard does not apper in /proc/mounts

On Mon, 2012-01-09 at 11:12 -0600, Eric Sandeen wrote:
 
> What kernel?

ierdnac-hp ~ # uname -a
Linux ierdnac-hp 3.1.6-pf-c220 #1 SMP PREEMPT Mon Jan 2 12:59:38 EET
2012 x86_64 Intel(R) Core(TM) i3 CPU M 380 @ 2.53GHz GenuineIntel
GNU/Linux

> If it's a recent kernel, here is the logic which controls whether to show it:
> 
>         if (test_opt(sb, DISCARD) && !(def_mount_opts & EXT4_DEFM_DISCARD))
>                 seq_puts(seq, ",discard");
> 
> i.e. if "discard" is in the default mount options for the fs, it is not
> shown, by design - although I am not 100% sure why that design decision
> was made; that logic was explicitly added here:

Indeed:
ierdnac-hp ~ # tune2fs -l /dev/sda3|grep discard
ierdnac-hp ~ # 
ierdnac-hp ~ # cat /proc/mounts |grep discard
/dev/root / ext4 rw,noatime,errors=remount-ro,user_xattr,acl,barrier=0,data=writeback,discard 0 0


Thank you for clarifing this !

-- 
Andrei Popa
(+4) 0741.57.80.90


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