Revert "autofs: work around unhappy compat problem on x86-64"

commit fcbf94b9dedd2ce08e798a99aafc94fec8668161 upstream.

This reverts commit a32744d4abae24572eff7269bc17895c41bd0085.

While that commit was technically the right thing to do, and made the
x86-64 compat mode work identically to native 32-bit mode (and thus
fixing the problem with a 32-bit systemd install on a 64-bit kernel), it
turns out that the automount binaries had workarounds for this compat
problem.

Now, the workarounds are disgusting: doing an "uname()" to find out the
architecture of the kernel, and then comparing it for the 64-bit cases
and fixing up the size of the read() in automount for those.  And they
were confused: it's not actually a generic 64-bit issue at all, it's
very much tied to just x86-64, which has different alignment for an
'u64' in 64-bit mode than in 32-bit mode.

But the end result is that fixing the compat layer actually breaks the
case of a 32-bit automount on a x86-64 kernel.

There are various approaches to fix this (including just doing a
"strcmp()" on current->comm and comparing it to "automount"), but I
think that I will do the one that teaches pipes about a special "packet
mode", which will allow user space to not have to care too deeply about
the padding at the end of the autofs packet.

That change will make the compat workaround unnecessary, so let's revert
it first, and get automount working again in compat mode.  The
packetized pipes will then fix autofs for systemd.

Reported-and-requested-by: Michael Tokarev <mjt@tls.msk.ru>
Cc: Ian Kent <raven@themaw.net>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
[bwh: Backported to 3.2: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --git a/fs/autofs4/autofs_i.h b/fs/autofs4/autofs_i.h
index 308a98bdb5f75a48c3e1434125a4a87ff58d8f13..326dc08d3e3f53aa075e68948e5e4598d548c263 100644 (file)
--- a/fs/autofs4/autofs_i.h
+++ b/fs/autofs4/autofs_i.h
@@ -110,7 +110,6 @@ struct autofs_sb_info {
        int sub_version;
        int min_proto;
        int max_proto;
-       int compat_daemon;
        unsigned long exp_timeout;
        unsigned int type;
        int reghost_enabled;

diff --git a/fs/autofs4/dev-ioctl.c b/fs/autofs4/dev-ioctl.c
index 56bac702ab09f656551800726628b5300db207a8..509fe1eb66ae31babcceda94ab8fd0a04268ebcb 100644 (file)
--- a/fs/autofs4/dev-ioctl.c
+++ b/fs/autofs4/dev-ioctl.c
@@ -385,7 +385,6 @@ static int autofs_dev_ioctl_setpipefd(struct file *fp,
                sbi->pipefd = pipefd;
                sbi->pipe = pipe;
                sbi->catatonic = 0;
-               sbi->compat_daemon = is_compat_task();
        }
 out:
        mutex_unlock(&sbi->wq_mutex);

diff --git a/fs/autofs4/inode.c b/fs/autofs4/inode.c
index 98a56950f6874d02745de134782e0bb7362d12e2..8179f1ab8175243905025444a5d58480f7098436 100644 (file)
--- a/fs/autofs4/inode.c
+++ b/fs/autofs4/inode.c
@@ -19,7 +19,6 @@
 #include <linux/parser.h>
 #include <linux/bitops.h>
 #include <linux/magic.h>
-#include <linux/compat.h>
 #include "autofs_i.h"
 #include <linux/module.h>
 
@@ -225,7 +224,6 @@ int autofs4_fill_super(struct super_block *s, void *data, int silent)
        set_autofs_type_indirect(&sbi->type);
        sbi->min_proto = 0;
        sbi->max_proto = 0;
-       sbi->compat_daemon = is_compat_task();
        mutex_init(&sbi->wq_mutex);
        spin_lock_init(&sbi->fs_lock);
        sbi->queues = NULL;

diff --git a/fs/autofs4/waitq.c b/fs/autofs4/waitq.c
index 6861f616342fb1f8a252fd1b7586e4973de80e8e..e1fbdeef85db2e4b73e78eaf6266d2784e2385b0 100644 (file)
--- a/fs/autofs4/waitq.c
+++ b/fs/autofs4/waitq.c
@@ -90,24 +90,7 @@ static int autofs4_write(struct file *file, const void *addr, int bytes)
 
        return (bytes > 0);
 }
-
-/*
- * The autofs_v5 packet was misdesigned.
- *
- * The packets are identical on x86-32 and x86-64, but have different
- * alignment. Which means that 'sizeof()' will give different results.
- * Fix it up for the case of running 32-bit user mode on a 64-bit kernel.
- */
-static noinline size_t autofs_v5_packet_size(struct autofs_sb_info *sbi)
-{
-       size_t pktsz = sizeof(struct autofs_v5_packet);
-#if defined(CONFIG_X86_64) && defined(CONFIG_COMPAT)
-       if (sbi->compat_daemon > 0)
-               pktsz -= 4;
-#endif
-       return pktsz;
-}
-
+       
 static void autofs4_notify_daemon(struct autofs_sb_info *sbi,
                                 struct autofs_wait_queue *wq,
                                 int type)
@@ -164,7 +147,8 @@ static void autofs4_notify_daemon(struct autofs_sb_info *sbi,
        {
                struct autofs_v5_packet *packet = &pkt.v5_pkt.v5_packet;
 
-               pktsz = autofs_v5_packet_size(sbi);
+               pktsz = sizeof(*packet);
+
                packet->wait_queue_token = wq->wait_queue_token;
                packet->len = wq->name.len;
                memcpy(packet->name, wq->name.name, wq->name.len);