LU-17202 target: set SB_KERNMOUNT

set SB_KERNMOUNT on server's mountpoint so umount process block
until the server (MDS/OST/MGS) is really umounted and released
the corresponding block device.

Lustre-change: https://review.whamcloud.com/52724
Lustre-commit: TBD (from 005a85f1c17a6c3477786a47dccfb67f2b36cb09)

Signed-off-by: Alex Zhuravlev <bzzz@whamcloud.com>
Change-Id: I03ac2dc6bb7cd4d93f5a1729fccb976aa1ebd5d4
Reviewed-on: https://review.whamcloud.com/c/ex/lustre-release/+/52725
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>

diff --git a/lustre/obdclass/obd_mount_server.c b/lustre/obdclass/obd_mount_server.c
index 47003be..54d4e92 100644 (file)
--- a/lustre/obdclass/obd_mount_server.c
+++ b/lustre/obdclass/obd_mount_server.c
@@ -1911,7 +1911,8 @@ static int server_fill_super_common(struct super_block *sb)
        sb->s_blocksize_bits = log2(sb->s_blocksize);
        sb->s_magic = LUSTRE_SUPER_MAGIC;
        sb->s_maxbytes = 0; /* we don't allow file IO on server mountpoints */
-       sb->s_flags |= SB_RDONLY;
+       /* set SB_KERNMOUNT to make umount synchronous */
+       sb->s_flags |= SB_RDONLY | SB_KERNMOUNT;
        sb->s_op = &server_ops;
 
        root = new_inode(sb);