linux-kernel - Re: (un)mount ramfs from C code

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Date:	Tue, 22 Sep 2009 14:53:53 -0500
From:	Tim Walberg <twalberg@...cast.net>
To:	Brian McGrew <brian@...ionpro.com>
Cc:	Luciano Rocha <luciano@...otux.com>, linux-kernel@...r.kernel.org
Subject: Re: (un)mount ramfs from C code

mount(2) (i.e. the system-call/library function) does not update /etc/mtab, IIRC...
mount(8) (the command-line utility) does...

In either case, I would expect the mount to show up in /proc/mounts (assuming
/proc is mounted).



On 09/22/2009 12:30 -0700, Brian McGrew wrote:
>>	> You mean without using system(3), right? System call is how your program
>>	> interacts with the outside world.
>>	> 
>>	> The relevant system calls are:
>>	>   - mount(2): mount("none", "/mnt", "ramfs", 0, NULL);
>>	>   - umount(2): umount("/mnt");
>>	> 
>>	
>>	Thanks for the help!  I'm getting there.  Considering the following:
>>	
>>	If (mount("ramfs", rd_path, "ramfs", MS_NOEXEC | MS_NOSUID, "size=2000m") <
>>	0) {
>>	    strerror(errno);
>>	} else {
>>	    std::cout << "mounted";
>>	}
>>	
>>	Works great!  Thank you.  However, even though the filesystem is mounted and
>>	/bin/mountpoint confirms it's a mountpoint, I do not see the mountpoint
>>	listed in /etc/mtab.
>>	
>>	Also, according to what I've read about ramfs, the size is supposed to be
>>	limited to size=, however, I can cat /dev/zero until the box it out of
>>	memory (and swap).
>>	
>>	I think I'm just missing something and google's not helping a whole lot
>>	since ramfs isn't the most popular subject today.
>>	
>>	Thanks,
>>	
>>	-b
>>	
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