tmpfs: generate random sb->s_uuid

amir73il · Christoph Hellwig · commit 2b4db79618ad · 2017-06-05T16:59:19.000+02:00
This is used by overlayfs to encode intrasystem unique file handles.

Suggested-by: Miklos Szeredi &lt;mszeredi@redhat.com&gt;
Cc: Hugh Dickins &lt;hughd@google.com&gt;
Cc: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Signed-off-by: Amir Goldstein &lt;amir73il@gmail.com&gt;
Signed-off-by: Christoph Hellwig &lt;hch@lst.de&gt;
diff --git a/mm/shmem.c b/mm/shmem.c
@@ -75,6 +75,7 @@ static struct vfsmount *shm_mnt;
 #include <uapi/linux/memfd.h>
 #include <linux/userfaultfd_k.h>
 #include <linux/rmap.h>
+#include <linux/uuid.h>
 
 #include <linux/uaccess.h>
 #include <asm/pgtable.h>
@@ -3761,6 +3762,7 @@ int shmem_fill_super(struct super_block *sb, void *data, int silent)
 #ifdef CONFIG_TMPFS_POSIX_ACL
 	sb->s_flags |= MS_POSIXACL;
 #endif
+	uuid_gen(&sb->s_uuid);
 
 	inode = shmem_get_inode(sb, NULL, S_IFDIR | sbinfo->mode, 0, VM_NORESERVE);
 	if (!inode)
