Re: Grow btrfs partition & filesystem backwards
On Wed, Nov 09, 2011 at 07:58:44PM +0100, Goffredo Baroncelli wrote: > On Wednesday, 09 November, 2011 08:36:24 Chris Mason wrote: > > The only choice for an online operation is to make a new partition in > > front of the old one and just add that as a second disk in btrfs. > > > > The slow method of shifting the bytes down is probably a better long > > term choice. > > > > -chris > > Hi Chris, > > does the chunk tree be able to map the sectors "before" ? If so we should > only > "shift down" the map logical->physical in the chunk tree/device tree. > > The only exception should be the superblock which has to be moved. > > At the mount time we should pass a parameter which set how the data should be > moved backward. Then the kernel remap the chunk tree/device tree. > > I don't know if the gains is greater than the work, but from a theoretical > point of view, it should be doable.. Agreed, if we wanted to sit down and write a tool, it wouldn't be that complex. The only tricky part is maintaining alignment and position of the super blocks. -chris -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: Grow btrfs partition & filesystem backwards
On Wednesday, 09 November, 2011 08:36:24 Chris Mason wrote: > The only choice for an online operation is to make a new partition in > front of the old one and just add that as a second disk in btrfs. > > The slow method of shifting the bytes down is probably a better long > term choice. > > -chris Hi Chris, does the chunk tree be able to map the sectors "before" ? If so we should only "shift down" the map logical->physical in the chunk tree/device tree. The only exception should be the superblock which has to be moved. At the mount time we should pass a parameter which set how the data should be moved backward. Then the kernel remap the chunk tree/device tree. I don't know if the gains is greater than the work, but from a theoretical point of view, it should be doable.. > > On Wed, Nov 09, 2011 at 06:40:06AM -0600, Billy Crook wrote: > > I think the biggest point of contention is that with all the stuff > > going on in the background in btrfs, its difficult to be sure that the > > resize operation has completed. With grows, you don't have to worry. > > With shrinks, if you truncate the block device too soon, you will > > corrupt the filesystem. > > > > 2011/11/9 Ernst Sjöstrand : > > > Gparted can do that, it just takes a very long time because it moves > > > everything back first. > > > > > > Regards > > > //Ernst > > > > > > On Wed, Nov 9, 2011 at 05:23, Jordan Windsor wrote: > > >> Hello, > > >> I was wondering how I would go about growing a btrfs filesystem > > >> backwards, I don't have any space to store the files temporally, > > >> I'd > > >> need to do it in place. > > >> Thanks. > > >> -- > > >> To unsubscribe from this list: send the line "unsubscribe > > >> linux-btrfs" in the body of a message to > > >> majord...@vger.kernel.org > > >> More majordomo info at http://vger.kernel.org/majordomo-info.html > > > > > > -- > > > To unsubscribe from this list: send the line "unsubscribe > > > linux-btrfs" in the body of a message to majord...@vger.kernel.org > > > More majordomo info at http://vger.kernel.org/majordomo-info.html > > > > -- > > To unsubscribe from this list: send the line "unsubscribe linux-btrfs" > > in > > the body of a message to majord...@vger.kernel.org > > More majordomo info at http://vger.kernel.org/majordomo-info.html > > -- > To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in > the body of a message to majord...@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html -- gpg key@ keyserver.linux.it: Goffredo Baroncelli (ghigo) Key fingerprint = 4769 7E51 5293 D36C 814E C054 BF04 F161 3DC5 0512 -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: Grow btrfs partition & filesystem backwards
The only choice for an online operation is to make a new partition in front of the old one and just add that as a second disk in btrfs. The slow method of shifting the bytes down is probably a better long term choice. -chris On Wed, Nov 09, 2011 at 06:40:06AM -0600, Billy Crook wrote: > I think the biggest point of contention is that with all the stuff > going on in the background in btrfs, its difficult to be sure that the > resize operation has completed. With grows, you don't have to worry. > With shrinks, if you truncate the block device too soon, you will > corrupt the filesystem. > > 2011/11/9 Ernst Sjöstrand : > > Gparted can do that, it just takes a very long time because it moves > > everything back first. > > > > Regards > > //Ernst > > > > On Wed, Nov 9, 2011 at 05:23, Jordan Windsor wrote: > >> Hello, > >> I was wondering how I would go about growing a btrfs filesystem > >> backwards, I don't have any space to store the files temporally, I'd > >> need to do it in place. > >> Thanks. > >> -- > >> To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in > >> the body of a message to majord...@vger.kernel.org > >> More majordomo info at http://vger.kernel.org/majordomo-info.html > >> > > -- > > To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in > > the body of a message to majord...@vger.kernel.org > > More majordomo info at http://vger.kernel.org/majordomo-info.html > > > -- > To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in > the body of a message to majord...@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: Grow btrfs partition & filesystem backwards
I think the biggest point of contention is that with all the stuff going on in the background in btrfs, its difficult to be sure that the resize operation has completed. With grows, you don't have to worry. With shrinks, if you truncate the block device too soon, you will corrupt the filesystem. 2011/11/9 Ernst Sjöstrand : > Gparted can do that, it just takes a very long time because it moves > everything back first. > > Regards > //Ernst > > On Wed, Nov 9, 2011 at 05:23, Jordan Windsor wrote: >> Hello, >> I was wondering how I would go about growing a btrfs filesystem >> backwards, I don't have any space to store the files temporally, I'd >> need to do it in place. >> Thanks. >> -- >> To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in >> the body of a message to majord...@vger.kernel.org >> More majordomo info at http://vger.kernel.org/majordomo-info.html >> > -- > To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in > the body of a message to majord...@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: Grow btrfs partition & filesystem backwards
Gparted can do that, it just takes a very long time because it moves everything back first. Regards //Ernst On Wed, Nov 9, 2011 at 05:23, Jordan Windsor wrote: > Hello, > I was wondering how I would go about growing a btrfs filesystem > backwards, I don't have any space to store the files temporally, I'd > need to do it in place. > Thanks. > -- > To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in > the body of a message to majord...@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
