> -----Original Message----- > From: linux-raid-owner@xxxxxxxxxxxxxxx [mailto:linux-raid- > owner@xxxxxxxxxxxxxxx] On Behalf Of Jeff Moyer > Sent: Thursday, February 17, 2011 6:04 PM > To: NeilBrown > Cc: Andrew Patterson; Jens Axboe; linux-raid@xxxxxxxxxxxxxxx; dm- > devel@xxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx > Subject: Re: [PATCH] Fix over-zealous flush_disk when changing device > size. > > NeilBrown <neilb@xxxxxxx> writes: > > > Hi Andrew (and others) > > I wonder if you would review the following for me and comment. > > > > Thanks, > > NeilBrown > > > > > > > > From e7f75c2a757108cdd83ce8c808a16bf27686c95f Mon Sep 17 00:00:00 2001 > > From: NeilBrown <neilb@xxxxxxx> > > Date: Thu, 17 Feb 2011 16:37:30 +1100 > > Subject: [PATCH] Fix over-zealous flush_disk when changing device > size. > > > > There are two cases when we call flush_disk. > > In one, the device has disappeared (check_disk_change) so any > > data will hold becomes irrelevant. > > In the oter, the device has changed size (check_disk_size_change) > > so data we hold may be irrelevant. > > > > In both cases it makes sense to discard any 'clean' buffers, > > so they will be read back from the device if needed. > > > > In the former case it makes sense to discard 'dirty' buffers > > as there will never be anywhere safe to write the data. In the > > second case it *does*not* make sense to discard dirty buffers > > as that will lead to file system corruption when you simply enlarge > > the containing devices. > > > > flush_disk calls __invalidate_devices. > > __invalidate_device calls both invalidate_inodes and invalidate_bdev. > > > > invalidate_inodes *does* discard I_DIRTY inodes and this does lead > > to fs corruption. > > > > invalidate_bev *does*not* discard dirty pages, but I don't really care > > about that at present. > > > > So this patch adds a flag to __invalidate_device (calling it > > __invalidate_device2) to indicate whether dirty buffers should be > > killed, and this is passed to invalidate_inodes which can choose to > > skip dirty inodes. > > > > flusk_disk then passes true from check_disk_change and false from > > check_disk_size_change. > > > > dm avoids tripping over this problem by calling i_size_write directly > > rathher than using check_disk_size_change. > > > > md does use check_disk_size_change and so is affected. > > > > This regression was introduced by commit 608aeef17a > > which causes check_disk_size_change to call > > flush_disk. > > This makes sense to me. Nice write-up, Neil. > > Acked-by: Jeff Moyer <jmoyer@xxxxxxxxxx> Neil, Is this fix is ready? If yes, where can I find it? BR Adam > -- > To unsubscribe from this list: send the line "unsubscribe linux-raid" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
