From: Michal Schmidt <mschmidt@redhat.com>
Date: Wed, 14 Nov 2007 16:13:28 +0100
Subject: [misc] tux: get rid of O_ATOMICLOOKUP
Message-id: 20071114161328.6c8529a9@brian.englab.brq.redhat.com
O-Subject: [RHEL5.2 PATCH] Get rid of Tux's O_ATOMICLOOKUP
Bugzilla: 358661

BZ: https://bugzilla.redhat.com/show_bug.cgi?id=358661

Description of the problem:
Ulrich reported a problem with the Tux patch which is included in RHEL.
Tux introduced a new open() flag O_ATOMICLOOKUP, but it was never
accepted upstream. Upstream later used the same bit for O_CLOEXEC. The
problem is there are people using modern glibcs (which attempt to use
O_CLOEXEC) on our RHEL kernels (which interpret it wrongly as
O_ATOMICLOOKUP). If the filename is not found in the dentry cache, this
results in open() returning -EWOULDBLOCKIO. Userspace does not expect
this. A kernel without support for O_CLOEXEC should just ignore the
flag and open the file successfully.

Ingo suggested O_ATOMICLOOKUP has only one user - the tux userspace
daemon. I could not find a single occurence of O_ATOMICLOOKUP in tux's
sources in RHEL-[345]. Therefore the number of users is closer to zero
than one. Neither the kernel parts of Tux use it.

Proposed fix:
The patch removes O_ATOMICLOOKUP completely from the kernel.

Testing:
I'm running a RHEL5 kernel with this patch, Tux is running and serving
files over HTTP no problem. Ulrich's testcase (see BZ) is fixed, open()
returns a valid fd instead of the error -530.

Upstream status:
The patch removes a piece was code which was never upstream.

Michal

Acked-by: Dave Jones <davej@redhat.com>

diff --git a/fs/namei.c b/fs/namei.c
index 6920c65..77a8460 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -1445,8 +1445,6 @@ static inline int lookup_flags(unsigned int f)
 	
 	if (f & O_DIRECTORY)
 		retval |= LOOKUP_DIRECTORY;
-	if (f & O_ATOMICLOOKUP)
-		retval |= LOOKUP_ATOMIC;
 
 	return retval;
 }
diff --git a/include/asm-alpha/fcntl.h b/include/asm-alpha/fcntl.h
index c3b88df..87f2cf4 100644
--- a/include/asm-alpha/fcntl.h
+++ b/include/asm-alpha/fcntl.h
@@ -14,7 +14,6 @@
 #define O_DIRECTORY	0100000	/* must be a directory */
 #define O_NOFOLLOW	0200000 /* don't follow links */
 #define O_LARGEFILE	0400000 /* will be set by the kernel on every open */
-#define O_ATOMICLOOKUP	01000000 /* do atomic file lookup */
 #define O_DIRECT	02000000 /* direct disk access - should check with OSF/1 */
 #define O_NOATIME	04000000
 
diff --git a/include/asm-generic/fcntl.h b/include/asm-generic/fcntl.h
index 5aa79cd..1e8abef 100644
--- a/include/asm-generic/fcntl.h
+++ b/include/asm-generic/fcntl.h
@@ -48,9 +48,6 @@
 #ifndef O_NOATIME
 #define O_NOATIME	01000000
 #endif
-#ifndef O_ATOMICLOOKUP
-#define O_ATOMICLOOKUP	02000000	/* do atomic file lookup */
-#endif
 
 #ifndef O_NDELAY
 #define O_NDELAY	O_NONBLOCK
diff --git a/include/asm-sparc/fcntl.h b/include/asm-sparc/fcntl.h
index 5fcdef6..5db60b5 100644
--- a/include/asm-sparc/fcntl.h
+++ b/include/asm-sparc/fcntl.h
@@ -14,7 +14,6 @@
 #define O_NDELAY	(0x0004 | O_NONBLOCK)
 #define O_NOCTTY	0x8000	/* not fcntl */
 #define O_LARGEFILE	0x40000
-#define O_ATOMICLOOKUP	0x80000 /* do atomic file lookup */
 #define O_DIRECT        0x100000 /* direct disk access hint */
 #define O_NOATIME	0x200000
 
diff --git a/include/asm-sparc64/fcntl.h b/include/asm-sparc64/fcntl.h
index 3fd6b0e..b2aecf0 100644
--- a/include/asm-sparc64/fcntl.h
+++ b/include/asm-sparc64/fcntl.h
@@ -14,7 +14,6 @@
 #define O_NONBLOCK	0x4000
 #define O_NOCTTY	0x8000	/* not fcntl */
 #define O_LARGEFILE	0x40000
-#define O_ATOMICLOOKUP	0x80000 /* do atomic file lookup */
 #define O_DIRECT        0x100000 /* direct disk access hint */
 #define O_NOATIME	0x200000