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>
diff --git a/fs/anon_inodes.c b/fs/anon_inodes.c
index 2c99459..598237e 100644
--- a/fs/anon_inodes.c
+++ b/fs/anon_inodes.c
@@ -89,11 +89,19 @@
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 @@
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;
