From 608aeef17a91747d6303de4df5e2c2e6899a95e8 Mon Sep 17 00:00:00 2001 From: Andrew Patterson Date: Thu, 4 Sep 2008 14:27:45 -0600 Subject: [PATCH] Call flush_disk() after detecting an online resize. We call flush_disk() to make sure the buffer cache for the disk is flushed after a disk resize. There are two resize cases, growing and shrinking. Given that users can shrink/then grow a disk before revalidate_disk() is called, we treat the grow case identically to shrinking. We need to flush the buffer cache after an online shrink because, as James Bottomley puts it, The two use cases for shrinking I can see are 1. planned: the fs is already shrunk to within the new boundaries and all data is relocated, so invalidate is fine (any dirty buffers that might exist in the shrunk region are there only because they were relocated but not yet written to their original location). 2. unplanned: In this case, the fs is probably toast, so whether we invalidate or not isn't going to make a whole lot of difference; it's still going to try to read or write from sectors beyond the new size and get I/O errors. Immediately invalidating shrunk disks will cause errors for outstanding I/Os for reads/write beyond the new end of the disk to be generated earlier then if we waited for the normal buffer cache operation. It also removes a potential security hole where we might keep old data around from beyond the end of the shrunk disk if the disk was not invalidated. Signed-off-by: Andrew Patterson Signed-off-by: Jens Axboe --- fs/block_dev.c | 1 + 1 file changed, 1 insertion(+) diff --git a/fs/block_dev.c b/fs/block_dev.c index 33650fc537c4..57e2786dd2a5 100644 --- a/fs/block_dev.c +++ b/fs/block_dev.c @@ -902,6 +902,7 @@ void check_disk_size_change(struct gendisk *disk, struct block_device *bdev) "%s: detected capacity change from %lld to %lld\n", name, bdev_size, disk_size); i_size_write(bdev->bd_inode, disk_size); + flush_disk(bdev); } } EXPORT_SYMBOL(check_disk_size_change); -- 2.30.2