Forwarding to dm-devel for those who don't read linux-kernel. ---------- Forwarded Message ---------- Subject: Re: online resizing of devices/filesystems (2.6) Date: Friday 17 October 2003 16:42 From: Kevin Corry <kevcorry@xxxxxxxxxx> To: Andrew Morton <akpm@xxxxxxxx> Cc: thornber@xxxxxxxxxxx, linux-kernel@xxxxxxxxxxxxxxx On Friday 17 October 2003 15:49, Kevin Corry wrote: > On Friday 17 October 2003 15:05, Andrew Morton wrote: > > So one approach would be to do what NBD does, and just write i_size > > directly. > > We had considered that originally. It just seemed like too big of a hack. > > :) Plus I wasn't sure if there were locking issues with changing fields in > > the inode. > > > You could create a little helper library function which takes i_sem and > > then writes i_size. But the VFS tends to avoid taking i_sem on blockdevs > > because it doesn't expect i_size to change ;) > > So...should I take i_sem or not? :) Perhaps calling i_size_write() in > include/linux/fs.h would be preferrable, since it seems to be doing > different things for SMP and preempt. > > Thanks for the feedback! Here's a patch that takes bdev->bd_inode->i_sem, and then calls i_size_write() to update the inode size. My initial tests have been successful in resizing mounted reiser and xfs filesystems on 2.6.0-test7. -- Kevin Corry kevcorry@xxxxxxxxxx http://evms.sourceforge.net/ When setting the size of a Device-Mapper device in the gendisk entry, also try to set the size of the corresponding block_device entry's inode. This is necessary to allow online device/filesystem resizing to work correctly. --- a/drivers/md/dm.c 9 Oct 2003 16:47:44 -0000 +++ b/drivers/md/dm.c 17 Oct 2003 21:06:01 -0000 @@ -726,6 +726,20 @@ up_write(&md->lock); } +static void __set_size(struct gendisk *disk, sector_t size) +{ + struct block_device *bdev; + + set_capacity(disk, size); + bdev = bdget_disk(disk, 0); + if (bdev) { + down(&bdev->bd_inode->i_sem); + i_size_write(bdev->bd_inode, size << SECTOR_SHIFT); + up(&bdev->bd_inode->i_sem); + bdput(bdev); + } +} + static int __bind(struct mapped_device *md, struct dm_table *t) { request_queue_t *q = md->queue; @@ -733,7 +747,7 @@ md->map = t; size = dm_table_get_size(t); - set_capacity(md->disk, size); + __set_size(md->disk, size); if (size == 0) return 0; ------------------------------------------------------- -- Kevin Corry kevcorry@xxxxxxxxxx http://evms.sourceforge.net/