linux-kernel - [PATCH 23/24] tmpfs: generate random sb->s

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Message-Id: <20170531161826.23243-24-hch@lst.de>
Date:   Wed, 31 May 2017 18:18:25 +0200
From:   Christoph Hellwig <hch@....de>
To:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Amir Goldstein <amir73il@...il.com>,
        linux-fsdevel@...r.kernel.org
Cc:     Shaohua Li <shli@...nel.org>,
        Dan Williams <dan.j.williams@...el.com>,
        David Howells <dhowells@...hat.com>,
        Steven Whitehouse <swhiteho@...hat.com>,
        Mimi Zohar <zohar@...ux.vnet.ibm.com>,
        linux-xfs@...r.kernel.org, linux-raid@...r.kernel.org,
        linux-nvdimm@...ts.01.org, linux-kernel@...r.kernel.org,
        linux-block@...r.kernel.org, Hugh Dickins <hughd@...gle.com>,
        Andrew Morton <akpm@...ux-foundation.org>
Subject: [PATCH 23/24] tmpfs: generate random sb->s_uuid

From: Amir Goldstein <amir73il@...il.com>

This is used by overlayfs to encode intrasystem unique file handles.

Suggested-by: Miklos Szeredi <mszeredi@...hat.com>
Cc: Hugh Dickins <hughd@...gle.com>
Cc: Andrew Morton <akpm@...ux-foundation.org>
Signed-off-by: Amir Goldstein <amir73il@...il.com>
Signed-off-by: Christoph Hellwig <hch@....de>
---
 mm/shmem.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/mm/shmem.c b/mm/shmem.c
index e67d6ba4e98e..391f2dcca727 100644
--- 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)
-- 
2.11.0