/**
* alloc_file - allocate and initialize a 'struct file'
* @mnt: the vfsmount on which the file will reside
* @dentry: the dentry representing the new file
* @mode: the mode with which the new file will be opened
* @fop: the 'struct file_operations' for the new file
*
* Use this instead of get_empty_filp() to get a new
* 'struct file'. Do so because of the same initialization
* pitfalls reasons listed for init_file(). This is a
* preferred interface to using init_file().
*
* If all the callers of init_file() are eliminated, its
* code should be moved into this function.
*/
struct file *alloc_file(struct path *path, fmode_t mode,
const struct file_operations *fop)
{
struct file *file;
file = get_empty_filp();
if (!file)
return NULL;
file->f_path = *path;
file->f_mapping = path->dentry->d_inode->i_mapping;
file->f_mode = mode;
file->f_op = fop;
/*
* These mounts don't really matter in practice
* for r/o bind mounts. They aren't userspace-
* visible. We do this for consistency, and so
* that we can do debugging checks at __fput()
*/
if ((mode & FMODE_WRITE) && !special_file(path->dentry->d_inode->i_mode)) {
file_take_write(file);
WARN_ON(mnt_clone_write(path->mnt));
}
ima_counts_get(file);
return file;
}
struct file *vfsub_dentry_open(struct path *path, int flags,
const struct cred *cred)
{
struct file *file;
file = dentry_open(path->dentry, path->mnt, flags, cred);
if (IS_ERR(file))
return file;
/* as NFSD does, just call ima_..._get() simply after dentry_open */
ima_counts_get(file);
return file;
}
static struct file *__dentry_open(struct dentry *dentry, struct vfsmount *mnt,
struct file *f,
int (*open)(struct inode *, struct file *),
const struct cred *cred)
{
struct inode *inode;
int error;
f->f_mode = OPEN_FMODE(f->f_flags) | FMODE_LSEEK |
FMODE_PREAD | FMODE_PWRITE;
inode = dentry->d_inode;
if (f->f_mode & FMODE_WRITE) {
error = __get_file_write_access(inode, mnt);
if (error)
goto cleanup_file;
if (!special_file(inode->i_mode))
file_take_write(f);
}
f->f_mapping = inode->i_mapping;
f->f_path.dentry = dentry;
f->f_path.mnt = mnt;
f->f_pos = 0;
f->f_op = fops_get(inode->i_fop);
file_sb_list_add(f, inode->i_sb);
error = security_dentry_open(f, cred);
if (error)
goto cleanup_all;
if (!open && f->f_op)
open = f->f_op->open;
if (open) {
error = open(inode, f);
if (error)
goto cleanup_all;
}
ima_counts_get(f);
f->f_flags &= ~(O_CREAT | O_EXCL | O_NOCTTY | O_TRUNC);
file_ra_state_init(&f->f_ra, f->f_mapping->host->i_mapping);
/* NB: we're sure to have correct a_ops only after f_op->open */
if (f->f_flags & O_DIRECT) {
if (!f->f_mapping->a_ops ||
((!f->f_mapping->a_ops->direct_IO) &&
(!f->f_mapping->a_ops->get_xip_mem))) {
fput(f);
f = ERR_PTR(-EINVAL);
}
}
return f;
cleanup_all:
fops_put(f->f_op);
if (f->f_mode & FMODE_WRITE) {
put_write_access(inode);
if (!special_file(inode->i_mode)) {
/*
* We don't consider this a real
* mnt_want/drop_write() pair
* because it all happenend right
* here, so just reset the state.
*/
file_reset_write(f);
mnt_drop_write(mnt);
}
}
file_sb_list_del(f);
f->f_path.dentry = NULL;
f->f_path.mnt = NULL;
cleanup_file:
put_filp(f);
dput(dentry);
mntput(mnt);
return ERR_PTR(error);
}
