gfs2-utils: master - mkfs.gfs2: Open the target device with O_EXCL

[Andrew Price]

Gitweb:        http://git.fedorahosted.org/git/?p=gfs2-utils.git;a=commitdiff;h=3d9879c4f7e...
Commit:        3d9879c4f7e27cad55e30b054ce570e601cf431a
Parent:        132c7cbafc706281f2aad97e205883123eb89550
Author:        Andrew Price 
AuthorDate:    Tue Apr 5 14:38:03 2016 +0100
Committer:     Andrew Price 
CommitterDate: Tue Apr 5 14:45:04 2016 +0100

mkfs.gfs2: Open the target device with O_EXCL

O_EXCL will let local mounters know that the device is busy while
mkfs.gfs2 is running so that they don't try to access it.

Before:
  # mount /dev/vdc /mnt/test
  mount: /dev/vdc: can't read superblock

With O_EXCL:
  # mount /dev/vdc /mnt/test
  mount: /dev/vdc is already mounted or /mnt/test busy

Signed-off-by: Andrew Price 
---
 gfs2/mkfs/main_mkfs.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/gfs2/mkfs/main_mkfs.c b/gfs2/mkfs/main_mkfs.c
index 107d3cc..4436f93 100644
--- a/gfs2/mkfs/main_mkfs.c
+++ b/gfs2/mkfs/main_mkfs.c
@@ -854,7 +854,7 @@ static void open_dev(struct mkfs_dev *dev)
 {
    int error;

-	dev->fd = open(dev->path, O_RDWR | O_CLOEXEC);
+	dev->fd = open(dev->path, O_RDWR|O_CLOEXEC|O_EXCL);
    if (dev->fd < 0) {
    	perror(dev->path);
    	exit(1);