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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/fs/autofs4/autofs_i.h b/fs/autofs4/autofs_i.h
index eb1cc92cd67d26d2966fa1191bb373f646144583..d8d8e7ba6a1e1bf52c367a73514aeaa202b8fcea 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 85f1fcdb30e75b4ad2da3d2dd8c1286664b6a3dd..76741d8d77866496496115312f6831b85cc51570 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 06858d955120ed43fab44309f1bc978f11c24124..e16980b00b8d7315dda8d7b92d93fdaf7062e843 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);
        mutex_init(&sbi->pipe_mutex);
        spin_lock_init(&sbi->fs_lock);

diff --git a/fs/autofs4/waitq.c b/fs/autofs4/waitq.c
index 9c098db433441a36613dd126b8487ed54036f49e..f624cd0ff84d38cb78257b8587baf34d20000418 100644 (file)
--- a/fs/autofs4/waitq.c
+++ b/fs/autofs4/waitq.c
@@ -92,23 +92,6 @@ static int autofs4_write(struct autofs_sb_info *sbi,
        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)
@@ -172,7 +155,8 @@ 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);