quota: kill the vfs_dq_off and vfs_dq_quota_on_remount wrappers

Instead of having wrappers in the VFS namespace export the dquot_suspend
and dquot_resume helpers directly.  Also rename vfs_quota_disable to
dquot_disable while we're at it.

[Jan Kara: Moved dquot_suspend to quotaops.h and made it inline]

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jan Kara <jack@suse.cz>
diff --git a/fs/jfs/super.c b/fs/jfs/super.c
index 5329d66..b8a07d4 100644
--- a/fs/jfs/super.c
+++ b/fs/jfs/super.c
@@ -401,14 +401,14 @@
 		sb->s_flags &= ~MS_RDONLY;
 
 		unlock_kernel();
-		vfs_dq_quota_on_remount(sb);
+		dquot_resume(sb, -1);
 		return ret;
 	}
 	if ((!(sb->s_flags & MS_RDONLY)) && (*flags & MS_RDONLY)) {
-		rc = vfs_dq_off(sb, 1);
-		if (rc < 0 && rc != -ENOSYS) {
+		rc = dquot_suspend(sb, -1);
+		if (rc < 0) {
 			unlock_kernel();
-			return -EBUSY;
+			return rc;
 		}
 		rc = jfs_umount_rw(sb);
 		JFS_SBI(sb)->flag = flag;