From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from ocean.emcraft.com ([213.221.7.182]) by bombadil.infradead.org with esmtps (Exim 4.68 #1 (Red Hat Linux)) id 1KFtNW-0005uB-B6 for linux-mtd@lists.infradead.org; Mon, 07 Jul 2008 16:15:50 +0000 Message-ID: <48724132.3050004@emcraft.com> Date: Mon, 07 Jul 2008 20:15:46 +0400 From: Sergei Poselenov MIME-Version: 1.0 To: linux-mtd@lists.infradead.org Subject: Re: JFFS2: real free capacity of the partition References: <486CFB83.3010301@emcraft.com> In-Reply-To: <486CFB83.3010301@emcraft.com> Content-Type: text/plain; charset=KOI8-R; format=flowed Content-Transfer-Encoding: 7bit List-Id: Linux MTD discussion mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Hello all, Seems I found why is that happens. In jffs2_statfs() the wasted_size is excluded from calculation: ... avail = c->dirty_size + c->free_size; ... Could someone explain for what reason? Have I understand it right - on the certain conditions, the wasted space can be converted to dirty space? Regards, Sergei Sergei Poselenov wrote: > Hello, > > Probably this is a trivial question and won't take much of your time. > > A simple test on a JFFS2 partition: > > # df > Filesystem 1k-blocks Used Available Use% Mounted on > /dev/mtdblock1 1024 376 648 37% /etc > # dd if=/dev/urandom of=tmp bs=1024 count=2900 > dd: tmp: No space left on device > # rm tmp > # df > Filesystem 1k-blocks Used Available Use% Mounted on > /dev/mtdblock1 1024 372 652 36% /etc > > Why additional space appeared? > > I've noted, that this effect: > - appeared only on the well-used partition, not on the > fresh-created one. > - appeared only after filling up the device > - appeared only once. On subsequent tests, the free space was > reported without magic increases. > > > Is this is an effect of the JFFS2 garbage collector? > Is there any method to learn the real available capacity of the > mounted partition? > > Thanks in advance, > Sergei >