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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>
This commit is contained in:
Roland Dreier 2009-12-18 09:41:24 -08:00 committed by Al Viro
parent ed2617585f
commit 628ff7c1d8
7 changed files with 17 additions and 9 deletions
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12
fs/anon_inodes.c
View File

@ -89,11 +89,19 @@ struct file *anon_inode_getfile(const char *name,
struct qstr this;
struct path path;
struct file *file;
fmode_t mode;
int error;
if (IS_ERR(anon_inode_inode))
return ERR_PTR(-ENODEV);
switch (flags & O_ACCMODE) {
case O_RDONLY: mode = FMODE_READ; break;
case O_WRONLY: mode = FMODE_WRITE; break;
case O_RDWR: mode = FMODE_READ | FMODE_WRITE; break;
default: return ERR_PTR(-EINVAL);
}
if (fops->owner && !try_module_get(fops->owner))
return ERR_PTR(-ENOENT);
@ -121,13 +129,13 @@ struct file *anon_inode_getfile(const char *name,
d_instantiate(path.dentry, anon_inode_inode);
error = -ENFILE;
file = alloc_file(&path, FMODE_READ | FMODE_WRITE, fops);
file = alloc_file(&path, mode, fops);
if (!file)
goto err_dput;
file->f_mapping = anon_inode_inode->i_mapping;
file->f_pos = 0;
file->f_flags = O_RDWR | (flags & O_NONBLOCK);
file->f_flags = flags & (O_ACCMODE | O_NONBLOCK);
file->f_version = 0;
file->private_data = priv;

2
fs/eventfd.c
View File

@ -339,7 +339,7 @@ struct file *eventfd_file_create(unsigned int count, int flags)
ctx->flags = flags;
file = anon_inode_getfile("[eventfd]", &eventfd_fops, ctx,
flags & EFD_SHARED_FCNTL_FLAGS);
O_RDWR | (flags & EFD_SHARED_FCNTL_FLAGS));
if (IS_ERR(file))
eventfd_free_ctx(ctx);

2
fs/eventpoll.c
View File

@ -1206,7 +1206,7 @@ SYSCALL_DEFINE1(epoll_create1, int, flags)
* a file structure and a free file descriptor.
*/
error = anon_inode_getfd("[eventpoll]", &eventpoll_fops, ep,
flags & O_CLOEXEC);
O_RDWR | (flags & O_CLOEXEC));
if (error < 0)
ep_free(ep);

2
fs/signalfd.c
View File

@ -236,7 +236,7 @@ SYSCALL_DEFINE4(signalfd4, int, ufd, sigset_t __user *, user_mask,
* anon_inode_getfd() will install the fd.
*/
ufd = anon_inode_getfd("[signalfd]", &signalfd_fops, ctx,
flags & (O_CLOEXEC | O_NONBLOCK));
O_RDWR | (flags & (O_CLOEXEC | O_NONBLOCK)));
if (ufd < 0)
kfree(ctx);
} else {

2
fs/timerfd.c
View File

@ -200,7 +200,7 @@ SYSCALL_DEFINE2(timerfd_create, int, clockid, int, flags)
hrtimer_init(&ctx->tmr, clockid, HRTIMER_MODE_ABS);
ufd = anon_inode_getfd("[timerfd]", &timerfd_fops, ctx,
flags & TFD_SHARED_FCNTL_FLAGS);
O_RDWR | (flags & TFD_SHARED_FCNTL_FLAGS));
if (ufd < 0)
kfree(ctx);

2
kernel/perf_event.c
View File

@ -4724,7 +4724,7 @@ SYSCALL_DEFINE5(perf_event_open,
if (IS_ERR(event))
goto err_put_context;
err = anon_inode_getfd("[perf_event]", &perf_fops, event, 0);
err = anon_inode_getfd("[perf_event]", &perf_fops, event, O_RDWR);
if (err < 0)
goto err_free_put_context;

4
virt/kvm/kvm_main.c
View File

@ -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);