From: Danny Feng <dfeng@redhat.com>
Date: Fri, 17 Jul 2009 04:09:48 -0400
Subject: [fs] procfs: fix fill all subdirs as DT_UNKNOWN
Message-id: 20090717080950.12701.35313.sendpatchset@danny
O-Subject: [PATCH RHEL5.5] procfs: fix proc_task_readdir fill all subdirs as DT_UNKNOWN
Bugzilla: 509713
RH-Acked-by: Stefan Assmann <sassmann@redhat.com>
RH-Acked-by: Dean Nelson <dnelson@redhat.com>
RH-Acked-by: John Feeney <jfeeney@redhat.com>

BZ#509713
https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=509713

Description:
/proc/<pid>/task/<tid> are directories, thus scandir() should return DT_DIR.
But RHEL5 or 2.6.18 kernel returns DT_UNKNOWN.

This bug came from a typo in 2.6.18 kernel, the typo in proc_task_readdir will
filldir all elements under /proc/<pid>/task/ (except . & ..) with type (DT_DIR < 0).
Since DT_DIR is always bigger than 0, then DT_UNKNOWN(=0) is filled instead of DT_DIR

Upstream status:
Later in 2.6.19, filldir was wrapped up with proc_pident_fill_cache for another
issue, proc_task_readdir then calls proc_pident_fill_cache instead. This bug is
eliminated naturally.

Brew build#:
https://brewweb.devel.redhat.com/taskinfo?taskID=1895952

KABI:
no harm

Test status:
I confirm this bug is fixed after testing with the reproduce testcase.

Signed-off-by: Danny Feng <dfeng@redhat.com>

diff --git a/fs/proc/base.c b/fs/proc/base.c
index 55daa0a..5f94ca7 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -2632,7 +2632,7 @@ static int proc_task_readdir(struct file * filp, void * dirent, filldir_t filldi
 		tid = task->pid;
 		len = snprintf(buf, sizeof(buf), "%d", tid);
 		ino = fake_ino(tid, PROC_TID_INO);
-		if (filldir(dirent, buf, len, pos, ino, DT_DIR < 0)) {
+		if (filldir(dirent, buf, len, pos, ino, DT_DIR) < 0) {
 			/* returning this tgid failed, save it as the first
 			 * pid for the next readir call */
 			filp->f_version = tid;