From 5ba99e361671bc22bfc3ce45d866826f297e25b7 Mon Sep 17 00:00:00 2001
From: Gabriel de Perthuis <g2p.code@gmail.com>
Date: Fri, 10 May 2013 19:53:28 +0200
Subject: [PATCH] hw/9pfs: Be robust against paths without FS_IOC_GETVERSION

9P optionally uses the FS_IOC_GETVERSION ioctl to get information about
a file's version (sometimes called generation number).

The code checks for supported filesystems at mount time, but some paths
may come from other mounted filesystems.

Change it to treat unsupported paths the same as unsupported
filesystems, returning 0 in both cases.

Note: ENOTTY is the error code for an unsupported ioctl.

This fix allows booting a linux kernel with the same / filesystem as the
host; otherwise the boot fails when mounting devtmpfs.

Signed-off-by: Gabriel de Perthuis <g2p.code@gmail.com>
Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
(cherry picked from commit db431f6adc881a0758512cd765b3108209013512)
---
 hw/9pfs/cofile.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/hw/9pfs/cofile.c b/hw/9pfs/cofile.c
index 2efebf3..194c130 100644
--- a/hw/9pfs/cofile.c
+++ b/hw/9pfs/cofile.c
@@ -38,6 +38,10 @@ int v9fs_co_st_gen(V9fsPDU *pdu, V9fsPath *path, mode_t st_mode,
             });
         v9fs_path_unlock(s);
     }
+    /* The ioctl may not be supported depending on the path */
+    if (err == -ENOTTY) {
+        err = 0;
+    }
     return err;
 }