From mboxrd@z Thu Jan 1 00:00:00 1970 From: Chris Mason Subject: Re: [PATCH] btrfs: Add a new mount option to grow the FS to the limit of the device Date: Wed, 4 Aug 2010 09:47:39 -0400 Message-ID: <20100804134739.GG16630@think> References: <4C5684D8.4080702@samsung.com> <20100803114947.GO16630@think> <4C595053.5030305@samsung.com> <20100804133051.GF16630@think> Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Cc: Donggeun Kim , linux-btrfs@vger.kernel.org, kyungmin.park@samsung.com To: Kyungmin Park Return-path: In-Reply-To: List-ID: On Wed, Aug 04, 2010 at 10:45:00PM +0900, Kyungmin Park wrote: > On Wed, Aug 4, 2010 at 10:30 PM, Chris Mason = wrote: > > On Wed, Aug 04, 2010 at 08:34:43PM +0900, Donggeun Kim wrote: > >> Chris Mason wrote: > >> > On Mon, Aug 02, 2010 at 05:42:00PM +0900, Donggeun Kim wrote: > >> >> In some cases, resizing a file system to the maximum device siz= e is required. > >> >> When flashing a file system image to a block device, > >> >> the file system does not fit into the block device's size. > >> >> Currently, executing 'btrfsctl' application is the only way > >> >> to grow the file system to the limit of the device. > >> >> If the mount option which alters the device size of a file syst= em > >> >> to the limit of the device is supported, > >> >> it can be useful regardless of the existence of 'btrfsctl' prog= ram. > >> >> This patch allows the file system to grow to the maximum size o= f the device > >> >> on mount time. > >> >> The new mount option name is 'maxsize'. > >> > > >> > I think this is a very useful feature, but could you please chan= ge the > >> > patch to allow controlling which device is resized? > >> > > >> > The ioctl allows you to pass in a device number (where the numbe= r comes > >> > from btrfs-show) > >> > > >> > Thanks! > >> > > >> > -chris > >> > > >> I'm sorry not to fully understand your comment. > >> Do you mean that device file name for being resized is specified a= fter 'maxsize' mount option? > >> e.g) #mount -o maxsize=3D/dev/sda1 ... > > > > In the resize ioctl you can pass a device number, something like 2:= max, > > which allows you to say make device #2 the full size of the device. > > > > btrfs-show can be used to find the correct device number for a give= n > > disk. =A0We don't use the device name because the scan might have f= ound a > > different device name to tie into the FS. > > > > Thanks, > > Chris >=20 > Before comments this issues. I first explain why this feature impleme= nted. >=20 > As you know, we implement the build image from some specific > directory. the size is maybe small than designed devices. e.g., build > image got the 400MiB but real device size has more the 8GiB. > after program the btrfs image, then it will be expanded at first boot= only. Yes, and this makes a lot of sense to me. I can see how the patch fits your usage and that you don't need the extra flag to pick a device on mounting. >=20 > Initial draft design is that add the some flag at build image. then i= t > checks it at first mount time. and expand to device size. > But after some study we know that btrfs supports resize feature. So w= e > implement it as patch. > Anyway that's our requirement. >=20 > as you provided usage, can you use the ioctl to achieve this > requirement? if not, we need to another method. Yes, the ioctl can currently pick a device to resize. In your case, there will only be one device and this isn't an issue. But, I'd like t= o see parity between what the mount option can do and what the ioctl can do, just so we are a little more consistent. -chris -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" = in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html