kernel/acct.c: use dedicated helper to access rlimit values

Use rlimit() helper instead of manually writing whole chain from
task to rlimit value. See patch "posix-cpu-timers: Use dedicated
helper to access rlimit values".

Link: https://lkml.kernel.org/r/20210728030822.524789-1-yang.yang29@zte.com.cn
Signed-off-by: Yang Yang <yang.yang29@zte.com.cn>
Reported-by: Zeal Robot <zealci@zte.com.cn>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: sh_def@163.com <sh_def@163.com>
Cc: Yang Yang <yang.yang29@zte.com.cn>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

kernel/acct.c

@@ -478,7 +478,7 @@ static void do_acct_process(struct bsd_acct_struct *acct)
 	/*
 	 * Accounting records are not subject to resource limits.
 	 */
-	flim = current->signal->rlim[RLIMIT_FSIZE].rlim_cur;
+	flim = rlimit(RLIMIT_FSIZE);
 	current->signal->rlim[RLIMIT_FSIZE].rlim_cur = RLIM_INFINITY;
 	/* Perform file operations on behalf of whoever enabled accounting */
 	orig_cred = override_creds(file->f_cred);