diskquota: 32bit quota tools on 64bit architectures

OpenVZ Linux kernel team has discovered the problem with 32bit quota tools
working on 64bit architectures.  In 2.6.10 kernel sys32_quotactl() function
was replaced by sys_quotactl() with the comment "sys_quotactl seems to be
32/64bit clean, enable it for 32bit" However this isn't right.  Look at
if_dqblk structure:

struct if_dqblk {
        __u64 dqb_bhardlimit;
        __u64 dqb_bsoftlimit;
        __u64 dqb_curspace;
        __u64 dqb_ihardlimit;
        __u64 dqb_isoftlimit;
        __u64 dqb_curinodes;
        __u64 dqb_btime;
        __u64 dqb_itime;
        __u32 dqb_valid;
};

For 32 bit quota tools sizeof(if_dqblk) == 0x44.
But for 64 bit kernel its size is 0x48, 'cause of alignment!
Thus we got a problem. Attached patch reintroduce sys32_quotactl() function,
that handles this and related situations.

[michal.k.k.piotrowski@gmail.com: build fix]
[akpm@linux-foundation.org: Make it link with CONFIG_QUOTA=n]
Signed-off-by: Vasily Tarasov <vtaras@openvz.org>
Cc: Andi Kleen <ak@suse.de>
Cc: "Luck, Tony" <tony.luck@intel.com>
Cc: Jan Kara <jack@ucw.cz>
Cc: <linux-arch@vger.kernel.org>
Signed-off-by: Michal Piotrowski <michal.k.k.piotrowski@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2 files changed, 2 insertions, 2 deletions

diff --git a/arch/ia64/ia32/ia32_entry.S b/arch/ia64/ia32/ia32_entry.S
index 99b665e2b1d5..06efd1f9b800 100644
--- a/arch/ia64/ia32/ia32_entry.S
+++ b/arch/ia64/ia32/ia32_entry.S
@@ -304,7 +304,7 @@ ia32_syscall_table:
         data8 sys_ni_syscall    /* init_module */
         data8 sys_ni_syscall    /* delete_module */
         data8 sys_ni_syscall    /* get_kernel_syms */  /* 130 */
-        data8 sys_quotactl
+        data8 sys32_quotactl
         data8 sys_getpgid
         data8 sys_fchdir
         data8 sys_ni_syscall    /* sys_bdflush */
diff --git a/arch/x86_64/ia32/ia32entry.S b/arch/x86_64/ia32/ia32entry.S
index 47565c3345d2..782dea819438 100644
--- a/arch/x86_64/ia32/ia32entry.S
+++ b/arch/x86_64/ia32/ia32entry.S
@@ -526,7 +526,7 @@ ia32_sys_call_table:
         .quad sys_init_module
         .quad sys_delete_module
         .quad quiet_ni_syscall          /* 130  get_kernel_syms */
-        .quad sys_quotactl
+        .quad sys32_quotactl
         .quad sys_getpgid
         .quad sys_fchdir
         .quad quiet_ni_syscall  /* bdflush */