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anonfd: Allow making anon files read-only

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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
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@@ -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;