fs: remove the unused SB_I_MULTIROOT flag

The last user of SB_I_MULTIROOT is disappeared with commit f2aedb71
("NFS: Add fs_context support.")
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

fs/namei.c

@@ -568,8 +568,8 @@ static bool path_connected(struct vfsmount *mnt, struct dentry *dentry)
 {
 	struct super_block *sb = mnt->mnt_sb;
 
-	/* Bind mounts and multi-root filesystems can have disconnected paths */
-	if (!(sb->s_iflags & SB_I_MULTIROOT) && (mnt->mnt_root == sb->s_root))
+	/* Bind mounts can have disconnected paths */
+	if (mnt->mnt_root == sb->s_root)
 		return true;
 
 	return is_subdir(dentry, mnt->mnt_root);

include/linux/fs.h

@@ -1385,7 +1385,6 @@ extern int send_sigurg(struct fown_struct *fown);
 #define SB_I_CGROUPWB	0x00000001	/* cgroup-aware writeback enabled */
 #define SB_I_NOEXEC	0x00000002	/* Ignore executables on this fs */
 #define SB_I_NODEV	0x00000004	/* Ignore devices on this fs */
-#define SB_I_MULTIROOT	0x00000008	/* Multiple roots to the dentry tree */
 
 /* sb->s_iflags to limit user namespace mounts */
 #define SB_I_USERNS_VISIBLE		0x00000010 /* fstype already mounted */