From 93b270f76e7ef3b81001576860c2701931cdc78b Mon Sep 17 00:00:00 2001 From: NeilBrown Date: Thu, 24 Feb 2011 17:25:47 +1100 Subject: 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, so it is suitable for any kernel since 2.6.27. Cc: stable@kernel.org Acked-by: Jeff Moyer Cc: Andrew Patterson Cc: Jens Axboe Signed-off-by: NeilBrown --- block/genhd.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'block') diff --git a/block/genhd.c b/block/genhd.c index 6a5b772aa201..cbf1112a885c 100644 --- a/block/genhd.c +++ b/block/genhd.c @@ -1355,7 +1355,7 @@ int invalidate_partition(struct gendisk *disk, int partno) struct block_device *bdev = bdget_disk(disk, partno); if (bdev) { fsync_bdev(bdev); - res = __invalidate_device(bdev); + res = __invalidate_device(bdev, true); bdput(bdev); } return res; -- cgit v1.2.3