[PATCH, resend] fs/proc/base.c: Expose file descriptors' f_pos

[Kenn Humborg]

The attached patch sets the "size" for the /proc/PID/fd/N entries
to the current file position (file->f_pos).

In proc_lookupfd(), I fill inode->i_size with file->f_pos.  Then
in pid_fd_revalidate(), I refresh it again.

I would find this useful to be able to tell, for example, how far
a large outgoing SMTP transfer has got (so I can avoid rebooting
if it's almost finished), or how far a customer download from our
FTP server has got to.

Was there any particular reason for fixing the "size" of these
files at 64?  Are there any tools that depend on this?

Patch is against 2.5.63, but should also apply to 2.5.64.

Later,
Kenn

--- src/fs/proc/base.c	Tue Feb 18 00:25:22 2003
+++ base.c	Mon Mar  3 19:55:15 2003
@@ -819,8 +819,11 @@
 		atomic_inc(&files->count);
 	task_unlock(task);
 	if (files) {
+		struct file *f;
 		read_lock(&files->file_lock);
-		if (fcheck_files(files, fd)) {
+		f = fcheck_files(files, fd);
+		if (f) {
+			dentry->d_inode->i_size = f->f_pos;
 			read_unlock(&files->file_lock);
 			put_files_struct(files);
 			return 1;
@@ -926,7 +929,7 @@
 	read_unlock(&files->file_lock);
 	put_files_struct(files);
 	inode->i_op = &proc_pid_link_inode_operations;
-	inode->i_size = 64;
+	inode->i_size = file->f_pos;
 	ei->op.proc_get_link = proc_fd_link;
 	dentry->d_op = &pid_fd_dentry_operations;
 	d_add(dentry, inode);