Revert "nfs: ignore SB_RDONLY when remounting nfs"

This reverts commit 80c4de6.

Silently ignoring the "ro" and "rw" mount options causes user confusion,
and regressions.

Reported-by: Alkis Georgopoulos<alkisg@gmail.com>
Cc: Li Lingfeng <lilingfeng3@huawei.com>
Fixes: 80c4de6 ("nfs: ignore SB_RDONLY when remounting nfs")
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>

Author: Trond Myklebust

fs/nfs/super.c

@@ -1051,16 +1051,6 @@ int nfs_reconfigure(struct fs_context *fc)
 
 	sync_filesystem(sb);
 
-	/*
-	 * The SB_RDONLY flag has been removed from the superblock during
-	 * mounts to prevent interference between different filesystems.
-	 * Similarly, it is also necessary to ignore the SB_RDONLY flag
-	 * during reconfiguration; otherwise, it may also result in the
-	 * creation of redundant superblocks when mounting a directory with
-	 * different rw and ro flags multiple times.
-	 */
-	fc->sb_flags_mask &= ~SB_RDONLY;
-
 	/*
 	 * Userspace mount programs that send binary options generally send
 	 * them populated with default values. We have no way to know which