anonfd: Allow making anon files read-only

It seems a couple places such as arch/ia64/kernel/perfmon.c and
drivers/infiniband/core/uverbs_main.c could use anon_inode_getfile()
instead of a private pseudo-fs + alloc_file(), if only there were a way
to get a read-only file.  So provide this by having anon_inode_getfile()
create a read-only file if we pass O_RDONLY in flags.

Signed-off-by: Roland Dreier <rolandd@cisco.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

1 files changed, 2 insertions, 2 deletions

diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index e1f2bf8d7b1e..b5af88167613 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -1177,7 +1177,7 @@ static struct file_operations kvm_vcpu_fops = {
  */
 static int create_vcpu_fd(struct kvm_vcpu *vcpu)
 {
-        return anon_inode_getfd("kvm-vcpu", &kvm_vcpu_fops, vcpu, 0);
+        return anon_inode_getfd("kvm-vcpu", &kvm_vcpu_fops, vcpu, O_RDWR);
 }
 
 /*
@@ -1638,7 +1638,7 @@ static int kvm_dev_ioctl_create_vm(void)
         kvm = kvm_create_vm();
         if (IS_ERR(kvm))
                 return PTR_ERR(kvm);
-        fd = anon_inode_getfd("kvm-vm", &kvm_vm_fops, kvm, 0);
+        fd = anon_inode_getfd("kvm-vm", &kvm_vm_fops, kvm, O_RDWR);
         if (fd < 0)
                 kvm_put_kvm(kvm);