From mboxrd@z Thu Jan 1 00:00:00 1970 From: Chris Mason Subject: Re: [PATCH] Btrfs: add a "df" ioctl for btrfs Date: Wed, 13 Jan 2010 09:29:23 -0500 Message-ID: <20100113142923.GL14979@think> References: <20100112202513.GA13414@localhost.localdomain> <20100113102503.GA6887@infradead.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Josef Bacik , linux-btrfs@vger.kernel.org To: Christoph Hellwig Return-path: In-Reply-To: <20100113102503.GA6887@infradead.org> List-ID: On Wed, Jan 13, 2010 at 05:25:03AM -0500, Christoph Hellwig wrote: > On Tue, Jan 12, 2010 at 03:25:13PM -0500, Josef Bacik wrote: > > df is a very loaded question in btrfs. This gives us a way to get the per-space > > usage information so we can tell exactly what is in use where. This will help > > us figure out ENOSPC problems, and help users better understand where their disk > > space is going. > > Just as discussed before I think it's a really bad idea. We always had > df reporting inconsistencies due to the way metadata is managed, and > btrfs isn't special in that way. This is more than just df being inaccurate, it's a way to find out how much space is used by each of the raid modes. We've had a ton of feature requests for this, and it really helps identify drives that have a ton of free space tied up for data vs metadata. -chris