[PATCH] diskquota: 32bit quota tools on 64bit architectures

[Vasily Tarasov <vtaras@openvz.org>]

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 the situation.

Signed-off-by: Vasily Tarasov <vtaras@openvz.org>
Acked-by: Dmitry Mishin <dim@openvz.org>

---

In OpenVZ technology 32 bit Virtual Environments over 
64 bit OS are common, hence we have customers, that complains on this bad quota
behaviour: 

# /usr/bin/quota
quota: error while getting quota from /dev/sda1 for 0: Success

The reason is caused above.

--- linux-2.6.18/arch/ia64/ia32/sys_ia32.c.quot32	2006-09-20 07:42:06.000000000 +0400
+++ linux-2.6.18/arch/ia64/ia32/sys_ia32.c	2006-10-19 11:17:50.000000000 +0400
@@ -2545,6 +2545,54 @@ long sys32_fadvise64_64(int fd, __u32 of
 			       advice); 
 } 
 
+asmlinkage long sys32_quotactl(unsigned int cmd, const char __user *special,
+						qid_t id, void __user *addr)
+{
+	long ret;
+	unsigned int cmds;
+	mm_segment_t old_fs;
+	struct if_dqblk dqblk;
+	struct if32_dqblk {
+		__u32 dqb_bhardlimit[2];
+		__u32 dqb_bsoftlimit[2];
+		__u32 dqb_curspace[2];
+		__u32 dqb_ihardlimit[2];
+		__u32 dqb_isoftlimit[2];
+		__u32 dqb_curinodes[2];
+		__u32 dqb_btime[2];
+		__u32 dqb_itime[2];
+		__u32 dqb_valid;
+	} dqblk32;
+
+	cmds = cmd >> SUBCMDSHIFT;
+
+	switch (cmds) {
+		case Q_GETQUOTA:
+			old_fs = get_fs();
+			set_fs(KERNEL_DS);
+			ret = sys_quotactl(cmd, special, id, &dqblk);
+			set_fs(old_fs);
+			memcpy(&dqblk32, &dqblk, sizeof(dqblk32));
+			dqblk32.dqb_valid = dqblk.dqb_valid;
+			if (copy_to_user(addr, &dqblk32, sizeof(dqblk32)))
+				return -EFAULT;
+			break;
+		case Q_SETQUOTA:
+			if (copy_from_user(&dqblk32, addr, sizeof(dqblk32)))
+				return -EFAULT;
+			memcpy(&dqblk, &dqblk32, sizeof(dqblk32));
+			dqblk.dqb_valid = dqblk32.dqb_valid;
+			old_fs = get_fs();
+			set_fs(KERNEL_DS);
+			ret = sys_quotactl(cmd, special, id, &dqblk);
+			set_fs(old_fs);
+			break;
+		default:
+			return sys_quotactl(cmd, special, id, addr);
+	}
+	return ret;
+}
+
 #ifdef	NOTYET  /* UNTESTED FOR IA64 FROM HERE DOWN */
 
 asmlinkage long sys32_setreuid(compat_uid_t ruid, compat_uid_t euid)
--- linux-2.6.18/arch/ia64/ia32/ia32_entry.S.quot32	2006-09-20 07:42:06.000000000 +0400
+++ linux-2.6.18/arch/ia64/ia32/ia32_entry.S	2006-10-19 11:15:52.000000000 +0400
@@ -341,7 +341,7 @@ 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 */
--- linux-2.6.18/arch/x86_64/ia32/ia32entry.S.quot32	2006-09-20 07:42:06.000000000 +0400
+++ linux-2.6.18/arch/x86_64/ia32/ia32entry.S	2006-10-18 10:05:53.000000000 +0400
@@ -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 */
--- linux-2.6.18/arch/x86_64/ia32/sys_ia32.c.quot32	2006-09-20 07:42:06.000000000 +0400
+++ linux-2.6.18/arch/x86_64/ia32/sys_ia32.c	2006-10-19 11:00:18.000000000 +0400
@@ -915,3 +915,50 @@ long sys32_lookup_dcookie(u32 addr_low, 
 	return sys_lookup_dcookie(((u64)addr_high << 32) | addr_low, buf, len);
 }
 
+asmlinkage long sys32_quotactl(unsigned int cmd, const char __user *special,
+						qid_t id, void __user *addr)
+{
+	long ret;
+	unsigned int cmds;
+	mm_segment_t old_fs;
+	struct if_dqblk dqblk;
+	struct if32_dqblk {
+		__u32 dqb_bhardlimit[2];
+		__u32 dqb_bsoftlimit[2];
+		__u32 dqb_curspace[2];
+		__u32 dqb_ihardlimit[2];
+		__u32 dqb_isoftlimit[2];
+		__u32 dqb_curinodes[2];
+		__u32 dqb_btime[2];
+		__u32 dqb_itime[2];
+		__u32 dqb_valid;
+	} dqblk32;
+
+	cmds = cmd >> SUBCMDSHIFT;
+
+	switch (cmds) {
+		case Q_GETQUOTA:
+			old_fs = get_fs();
+			set_fs(KERNEL_DS);
+			ret = sys_quotactl(cmd, special, id, &dqblk);
+			set_fs(old_fs);
+			memcpy(&dqblk32, &dqblk, sizeof(dqblk32));
+			dqblk32.dqb_valid = dqblk.dqb_valid;
+			if (copy_to_user(addr, &dqblk32, sizeof(dqblk32)))
+				return -EFAULT;
+			break;
+		case Q_SETQUOTA:
+			if (copy_from_user(&dqblk32, addr, sizeof(dqblk32)))
+				return -EFAULT;
+			memcpy(&dqblk, &dqblk32, sizeof(dqblk32));
+			dqblk.dqb_valid = dqblk32.dqb_valid;
+			old_fs = get_fs();
+			set_fs(KERNEL_DS);
+			ret = sys_quotactl(cmd, special, id, &dqblk);
+			set_fs(old_fs);
+			break;
+		default:
+			return sys_quotactl(cmd, special, id, addr);
+	}
+	return ret;
+}