[PATCH 3/3] nbd: Use invalidate_gendisk() helper on disconnect

[Xie Yongji <xieyongji@bytedance.com>]

When a nbd device encounters a writeback error, that error will
get propagated to the bd_inode's wb_err field. Then if this nbd
device's backend is disconnected and another is attached, we will
get back the previous writeback error on fsync, which is unexpected.

To fix it, let's use invalidate_gendisk() helper to invalidate the
disk on disconnect instead of just setting disk's capacity to zero.

Reported-by: Yi Xingchen <yixingchen@bytedance.com>
Signed-off-by: Xie Yongji <xieyongji@bytedance.com>
---
 drivers/block/nbd.c | 12 +++---------
 1 file changed, 3 insertions(+), 9 deletions(-)

diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c
index 5170a630778d..64ae087d8767 100644
--- a/drivers/block/nbd.c
+++ b/drivers/block/nbd.c
@@ -305,14 +305,6 @@ static void nbd_mark_nsock_dead(struct nbd_device *nbd, struct nbd_sock *nsock,
 	nsock->sent = 0;
 }
 
-static void nbd_size_clear(struct nbd_device *nbd)
-{
-	if (nbd->config->bytesize) {
-		set_capacity(nbd->disk, 0);
-		kobject_uevent(&nbd_to_dev(nbd)->kobj, KOBJ_CHANGE);
-	}
-}
-
 static int nbd_set_size(struct nbd_device *nbd, loff_t bytesize,
 		loff_t blksize)
 {
@@ -1232,7 +1224,9 @@ static void nbd_config_put(struct nbd_device *nbd)
 					&nbd->config_lock)) {
 		struct nbd_config *config = nbd->config;
 		nbd_dev_dbg_close(nbd);
-		nbd_size_clear(nbd);
+		invalidate_gendisk(nbd->disk);
+		if (nbd->config->bytesize)
+			kobject_uevent(&nbd_to_dev(nbd)->kobj, KOBJ_CHANGE);
 		if (test_and_clear_bit(NBD_RT_HAS_PID_FILE,
 				       &config->runtime_flags))
 			device_remove_file(disk_to_dev(nbd->disk), &pid_attr);
-- 
2.11.0