On Mon, Mar 20, 2017 at 3:58 PM, Ming Lin <mlin@xxxxxxxxxx> wrote:
> From: Ratna Manoj Bolla <manoj.br@xxxxxxxxx>
>
> When a filesystem is mounted on a nbd device and on a disconnect, because
> of kill_bdev(), and resetting bdev size to zero, buffer_head mappings are
> getting destroyed under mounted filesystem.
>
> After a bdev size reset(i.e bdev->bd_inode->i_size = 0) on a disconnect,
> followed by a sys_umount(),
> generic_shutdown_super()->...
> ->__sync_blockdev()->...
> -blkdev_writepages()->...
> ->do_invalidatepage()->...
> -discard_buffer() is discarding superblock buffer_head assumed
> to be in mapped state by ext4_commit_super().
>
> [mlin: ported to 4.11-rc2]
> Signed-off-by: Ratna Manoj Bolla <manoj.br@xxxxxxxxx
> ---
> drivers/block/nbd.c | 8 ++++++--
> 1 file changed, 6 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c
> index cb4ccfc..a6a3643 100644
> --- a/drivers/block/nbd.c
> +++ b/drivers/block/nbd.c
> @@ -125,7 +125,8 @@ static const char *nbdcmd_to_ascii(int cmd)
>
> static int nbd_size_clear(struct nbd_device *nbd, struct block_device *bdev)
> {
> - bd_set_size(bdev, 0);
> + if (bdev->bd_openers <= 1)
> + bd_set_size(bdev, 0);
> set_capacity(nbd->disk, 0);
> kobject_uevent(&nbd_to_dev(nbd)->kobj, KOBJ_CHANGE);
>
> @@ -603,6 +604,8 @@ static void nbd_reset(struct nbd_device *nbd)
>
> static void nbd_bdev_reset(struct block_device *bdev)
> {
> + if (bdev->bd_openers > 1)
> + return;
> set_device_ro(bdev, false);
> bdev->bd_inode->i_size = 0;
> if (max_part > 0) {
> @@ -666,7 +669,8 @@ static int nbd_clear_sock(struct nbd_device *nbd, struct block_device *bdev)
> {
> sock_shutdown(nbd);
> nbd_clear_que(nbd);
> - kill_bdev(bdev);
> +
> + __invalidate_device(bdev, true);
> nbd_bdev_reset(bdev);
> /*
> * We want to give the run thread a chance to wait for everybody
> --
> 1.8.3.1
Hi Josef,
Any comments?
Thanks,
Ming
