Commit 1ae9bd8b authored by Al Viro's avatar Al Viro
Browse files

proc_lookupfd_common(): don't bother with instantiate unless the file is open 



... and take the "check if file is open, pick ->f_mode" into a helper;
tid_fd_revalidate() can use it.

The next patch will get rid of tid_fd_revalidate() calls in instantiate
callbacks.

Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent 1bbc5513

fs/proc/fd.c

+34 −29
Original line number Diff line number Diff line
@@ -81,12 +81,29 @@ static const struct file_operations proc_fdinfo_file_operations = { 
	.release	= single_release,

};



static bool tid_fd_mode(struct task_struct *task, unsigned fd, fmode_t *mode)

{

	struct files_struct *files = get_files_struct(task);

	struct file *file;



	if (!files)

		return false;



	rcu_read_lock();

	file = fcheck_files(files, fd);

	if (file)

		*mode = file->f_mode;

	rcu_read_unlock();

	put_files_struct(files);

	return !!file;

}



static int tid_fd_revalidate(struct dentry *dentry, unsigned int flags)

{

	struct files_struct *files;

	struct task_struct *task;

	struct inode *inode;

	unsigned int fd;

	fmode_t f_mode;



	if (flags & LOOKUP_RCU)

		return -ECHILD;
@@ -96,18 +113,7 @@ static int tid_fd_revalidate(struct dentry *dentry, unsigned int flags) 
	fd = proc_fd(inode);



	if (task) {

		files = get_files_struct(task);

		if (files) {

			struct file *file;



			rcu_read_lock();

			file = fcheck_files(files, fd);

			if (file) {

				unsigned f_mode = file->f_mode;



				rcu_read_unlock();

				put_files_struct(files);



		if (tid_fd_mode(task, fd, &f_mode)) {

			task_dump_owner(task, 0, &inode->i_uid, &inode->i_gid);



			if (S_ISLNK(inode->i_mode)) {
@@ -118,14 +124,10 @@ static int tid_fd_revalidate(struct dentry *dentry, unsigned int flags) 
					i_mode |= S_IWUSR | S_IXUSR;

				inode->i_mode = i_mode;

			}



			security_task_to_inode(task, inode);

			put_task_struct(task);

			return 1;

		}

			rcu_read_unlock();

			put_files_struct(files);

		}

		put_task_struct(task);

	}

	return 0;
@@ -203,11 +205,14 @@ static struct dentry *proc_lookupfd_common(struct inode *dir, 
	struct task_struct *task = get_proc_task(dir);

	int result = -ENOENT;

	unsigned fd = name_to_int(&dentry->d_name);

	fmode_t f_mode;



	if (!task)

		goto out_no_task;

	if (fd == ~0U)

		goto out;

	if (!tid_fd_mode(task, fd, &f_mode))

		goto out;



	result = instantiate(dir, dentry, task, (void *)(unsigned long)fd);

out: