[PATCH] fix RLIM_NOFILE handling

* dup2() should return -EBADF on exceeded sysctl_nr_open
* dup() should *not* return -EINVAL even if you have rlimit set to 0;
  it should get -EMFILE instead.

Check for orig_start exceeding rlimit taken to sys_fcntl().
Failing expand_files() in dup{2,3}() now gets -EMFILE remapped to -EBADF.
Consequently, remaining checks for rlimit are taken to expand_files().

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

fs/open.c

@@ -972,7 +972,6 @@ int get_unused_fd_flags(int flags)
 	int fd, error;
 	struct fdtable *fdt;
 
-  	error = -EMFILE;
 	spin_lock(&files->file_lock);
 
 repeat:
@@ -980,13 +979,6 @@ repeat:
 	fd = find_next_zero_bit(fdt->open_fds->fds_bits, fdt->max_fds,
 				files->next_fd);
 
-	/*
-	 * N.B. For clone tasks sharing a files structure, this test
-	 * will limit the total number of files that can be opened.
-	 */
-	if (fd >= current->signal->rlim[RLIMIT_NOFILE].rlim_cur)
-		goto out;
-
 	/* Do we need to expand the fd array or fd set?  */
 	error = expand_files(files, fd);
 	if (error < 0)
@@ -997,7 +989,6 @@ repeat:
 	 	 * If we needed to expand the fs array we
 		 * might have blocked - try again.
 		 */
-		error = -EMFILE;
 		goto repeat;
 	}