[Top] [All Lists]

Re: [PATCH v2] Check for immutable flag in fallocate path

To: Dave Chinner <david@xxxxxxxxxxxxx>
Subject: Re: [PATCH v2] Check for immutable flag in fallocate path
From: Marco Stornelli <marco.stornelli@xxxxxxxxx>
Date: Fri, 04 Mar 2011 09:17:00 +0100
Cc: Linux Kernel <linux-kernel@xxxxxxxxxxxxxxx>, linux-ext4@xxxxxxxxxxxxxxx, linux-btrfs@xxxxxxxxxxxxxxx, cluster-devel@xxxxxxxxxx, xfs@xxxxxxxxxxx, Linux FS Devel <linux-fsdevel@xxxxxxxxxxxxxxx>
Dkim-signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:message-id:date:from:user-agent:mime-version:to :cc:subject:references:in-reply-to:content-type :content-transfer-encoding; bh=JAR675HN3QrDVJJ49hHC0khfXqOQ2x5q5DGam184HZQ=; b=gAikRSh2Hsg6EsFchz9RnTNTyMBH/VyrUgJVfJjjhGmHiuZVGDAxZowyewpe3uOwQK eJKzElN+pF7yVYto7f+aaXQSCbTvHgry2hzZjzC5TmbTIayEJvqKXvxKLW2EYszMhHyP BGLwRouwogngyV+wYyVOFweZ1h46zSlOBPb54=
Domainkey-signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=message-id:date:from:user-agent:mime-version:to:cc:subject :references:in-reply-to:content-type:content-transfer-encoding; b=aLmXA6qhQQX3EZdpj6/73PnuG/yzxGYXC1MgFo/GK5dA58ilDiNHNoKKIFQVC5S8Ml J8TGtieJ5czYIzBNxklm/+oxoCjUH2T50fXQtI8vzZxZDsfDTruRIyLO1wt5RCIMzEFF pS7Fu9yszwDyF8WqeIZFQ4ILVK8c//aTkod4c=
In-reply-to: <20110303213903.GL15097@dastard>
References: <4D6221B8.9040303@xxxxxxxxx> <4D6F5473.2070709@xxxxxxxxx> <20110303213903.GL15097@dastard>
User-agent: Mozilla/5.0 (X11; U; Linux i686; it; rv: Gecko/20101125 SUSE/3.0.11 Thunderbird/3.0.11
Hi Dave,

Il 03/03/2011 22:39, Dave Chinner ha scritto:
> WTF?  Why does append mode have any effect on whether we can punch
> holes in a file or not? There's no justification for adding this in
> the commit message. Why is it even in a patch that is for checking
> immutable inodes? What is the point of adding it, when all that will
> happen is people will switch to XFS_IOC_UNRESVSP which has never had
> this limitation?

So according to you, it's legal to do an "unreserve" operation on an
append-only file. It's not the same for me, but if the community said
that this is the right behavior then ok.

> And this asks bigger questions - why would you allow preallocate
> anywhere but at or beyond EOF on an append mode inode? You can only
> append to the file, so if you're going to add limitations based on
> the append flag, you need to think this through a bit more....

I don't understand this point. The theory of operation was:

1) we don't allow any operation (reserve/unreserve) on a immutable file;
2) we don't allow *unreserve* operation on an append-only file (this
check makes sense only for fs that support the unreserve operation).

> Also, like Christoph said, these checks belong in the generic code,
> not in every filesystem. The same checks have to be made for every
> filesystem, so they should be done before calling out the
> filesystems regardless of what functionality the filesystem actually
> supports.

This was related to the first point, if we remove it then it's ok to
check in a common code. Even if I think we should do the check under the
inode lock to avoid race between fallocate and setattr, isn't it?


<Prev in Thread] Current Thread [Next in Thread>