Home » Mailing lists » Devel » [PATCH] diskquota: 32bit quota tools on 64bit architectures
| [PATCH] diskquota: 32bit quota tools on 64bit architectures [message #7646] |
Thu, 19 October 2006 12:30  |
|
|
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;
+}
|
|
|
|
|
|
| Re: [PATCH] diskquota: 32bit quota tools on 64bit architectures [message #7662 is a reply to message #7646] |
Thu, 19 October 2006 15:20  |
rdunlap
Messages: 11
Registered: May 2006
|
Junior Member |
|
|
On Thu, 19 Oct 2006 16:32:07 +0400 Vasily Tarasov wrote:
> --- 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)
> +{
> +
> + 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;
> +}
Please align the switch and case/default source lines.
We prefer not to "double-indent" each case block inside a switch.
I suppose I should try to add this to CodingStyle since it's
not there.
> --- 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)
> +{
> +
> + 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);
> + }
---
~Randy
|
|
|
|
| Re: [PATCH] diskquota: 32bit quota tools on 64bit architectures [message #7664 is a reply to message #7646] |
Thu, 19 October 2006 17:29 |
Christoph Hellwig
Messages: 59
Registered: April 2006
|
Member |
|
|
On Thu, Oct 19, 2006 at 04:32:07PM +0400, Vasily Tarasov wrote:
> +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);
Please allocate the structure using compat_alloc_userspace and copy
with copy_in_user instead of the set_fs trick.
|
|
|
|
|
|
|
|
| Re: [PATCH] diskquota: 32bit quota tools on 64bit architectures [message #7678 is a reply to message #7646] |
Fri, 20 October 2006 06:28 |
|
|
Andi Kleen wrote:
<snip>
> Thanks. But the code should be probably common somewhere in fs/*, not
> duplicated.
<snip>
Thank you for the comment!
I'm not sure we should do it. If we move the code in fs/quota.c for example,
than this code will be compiled for _all_ arhitectures, not only for x86_64 and ia64.
Of course, we can surround this code by #ifdefs <ARCH>, but I thought this is
a bad style... Moreover looking through current kernel code, I found out that
usually code is duplicated in such cases.
However, if you insist I'll modify the code! :)
Thank you.
|
|
|
|
| Re: [PATCH] diskquota: 32bit quota tools on 64bit architectures [message #7680 is a reply to message #7678] |
Fri, 20 October 2006 07:12 |
Christoph Hellwig
Messages: 59
Registered: April 2006
|
Member |
|
|
On Fri, Oct 20, 2006 at 10:30:04AM +0400, Vasily Tarasov wrote:
> Andi Kleen wrote:
>
> <snip>
> > Thanks. But the code should be probably common somewhere in fs/*, not
> > duplicated.
> <snip>
>
> Thank you for the comment!
> I'm not sure we should do it. If we move the code in fs/quota.c for example,
> than this code will be compiled for _all_ arhitectures, not only for x86_64 and ia64.
> Of course, we can surround this code by #ifdefs <ARCH>, but I thought this is
> a bad style... Moreover looking through current kernel code, I found out that
> usually code is duplicated in such cases.
>
> However, if you insist I'll modify the code! :)
I suspect a compat_x86.c file somehwere might make sense, as only x86 has
the wierd alignment rules, but we have two architectures that allow to run
x86 binaries with the compat subszstem. Now the big question: where should
we put this file?
>
> Thank you.
>
> -
> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at http://vger.kernel.org/majordomo-info.html
> Please read the FAQ at http://www.tux.org/lkml/
---end quoted text---
|
|
|
|
|
|
| Re: [PATCH] diskquota: 32bit quota tools on 64bit architectures [message #7707 is a reply to message #7677] |
Sat, 21 October 2006 16:28 |
Arnd Bergmann
Messages: 10
Registered: February 2006
|
Junior Member |
|
|
On Friday 20 October 2006 08:10, Vasily Tarasov wrote:
> Christoph Hellwig wrote:
>
> <snip>
>
> > Please allocate the structure using compat_alloc_userspace and copy
> > with copy_in_user instead of the set_fs trick.
>
> <snip>
>
> Good idea, thank you for your tip, I'll do it.
I think it would be even better to integrate this into fs/quota.c
and get rid of the extra copy entirely. The only thing you need
to do differently in case of 32 bit Q_GETQUOTA is the size
of the copy_{from,to}_user.
On a related topic, I just noticed
typedef struct fs_qfilestat {
__u64 qfs_ino; /* inode number */
__u64 qfs_nblks; /* number of BBs 512-byte-blks */
__u32 qfs_nextents; /* number of extents */
} fs_qfilestat_t;
typedef struct fs_quota_stat {
__s8 qs_version; /* version number for future changes */
__u16 qs_flags; /* XFS_QUOTA_{U,P,G}DQ_{ACCT,ENFD} */
__s8 qs_pad; /* unused */
fs_qfilestat_t qs_uquota; /* user quota storage information */
fs_qfilestat_t qs_gquota; /* group quota storage information */
__u32 qs_incoredqs; /* number of dquots incore */
__s32 qs_btimelimit; /* limit for blks timer */
__s32 qs_itimelimit; /* limit for inodes timer */
__s32 qs_rtbtimelimit;/* limit for rt blks timer */
__u16 qs_bwarnlimit; /* limit for num warnings */
__u16 qs_iwarnlimit; /* limit for num warnings */
} fs_quota_stat_t;
This one seems to have a more severe problem in x86_64 compat
mode. I haven't tried it, but isn't everything down from
gs_gquota aligned differently on i386?
Arnd <><
|
|
|
|
| Re: [PATCH] diskquota: 32bit quota tools on 64bit architectures [message #7722 is a reply to message #7707] |
Mon, 23 October 2006 02:12 |
David Chinner
Messages: 4
Registered: October 2006
|
Junior Member |
|
|
On Sat, Oct 21, 2006 at 06:28:32PM +0200, Arnd Bergmann wrote:
> On a related topic, I just noticed
>
> typedef struct fs_qfilestat {
> __u64 qfs_ino; /* inode number */
> __u64 qfs_nblks; /* number of BBs 512-byte-blks */
> __u32 qfs_nextents; /* number of extents */
> } fs_qfilestat_t;
>
> typedef struct fs_quota_stat {
> __s8 qs_version; /* version number for future changes */
> __u16 qs_flags; /* XFS_QUOTA_{U,P,G}DQ_{ACCT,ENFD} */
> __s8 qs_pad; /* unused */
> fs_qfilestat_t qs_uquota; /* user quota storage information */
> fs_qfilestat_t qs_gquota; /* group quota storage information */
> __u32 qs_incoredqs; /* number of dquots incore */
> __s32 qs_btimelimit; /* limit for blks timer */
> __s32 qs_itimelimit; /* limit for inodes timer */
> __s32 qs_rtbtimelimit;/* limit for rt blks timer */
> __u16 qs_bwarnlimit; /* limit for num warnings */
> __u16 qs_iwarnlimit; /* limit for num warnings */
> } fs_quota_stat_t;
Ah, the XFS quota structures.....
> This one seems to have a more severe problem in x86_64 compat
> mode. I haven't tried it, but isn't everything down from
> gs_gquota aligned differently on i386?
Yes - this is just one of several interfaces into XFS that need compat
handling that don't have them right now.
Cheers,
Dave.
--
Dave Chinner
Principal Engineer
SGI Australian Software Group
|
|
|
|
| Re: [PATCH] diskquota: 32bit quota tools on 64bit architectures [message #7729 is a reply to message #7707] |
Mon, 23 October 2006 10:50 |
|
|
Hello,
Arnd Bergmann wrote:
<snip>
> On a related topic, I just noticed
>
> typedef struct fs_qfilestat {
> __u64 qfs_ino; /* inode number */
> __u64 qfs_nblks; /* number of BBs 512-byte-blks */
> __u32 qfs_nextents; /* number of extents */
> } fs_qfilestat_t;
>
> typedef struct fs_quota_stat {
> __s8 qs_version; /* version number for future changes */
> __u16 qs_flags; /* XFS_QUOTA_{U,P,G}DQ_{ACCT,ENFD} */
> __s8 qs_pad; /* unused */
> fs_qfilestat_t qs_uquota; /* user quota storage information */
> fs_qfilestat_t qs_gquota; /* group quota storage information */
> __u32 qs_incoredqs; /* number of dquots incore */
> __s32 qs_btimelimit; /* limit for blks timer */
> __s32 qs_itimelimit; /* limit for inodes timer */
> __s32 qs_rtbtimelimit;/* limit for rt blks timer */
> __u16 qs_bwarnlimit; /* limit for num warnings */
> __u16 qs_iwarnlimit; /* limit for num warnings */
> } fs_quota_stat_t;
>
> This one seems to have a more severe problem in x86_64 compat
> mode. I haven't tried it, but isn't everything down from
> gs_gquota aligned differently on i386?
<snip>
The problem indeed exists:
ia32:
sizeof(fs_qfilestat) = 0x14
sizeof(fs_quota_stat) = 0x44
x86_64:
sizeof(fs_qfilestat) = 0x18
sizeof(fs_quota_stat) = 0x50
Note, that the difference between sizes of fs_qfilestat on ia32 and
on x86_64 doesn't equal 8 bytes, as was expected (by me :)), but equals 12 bytes:
'cause of padding at the end of fs_quota_stat structure on x86_64.
I will add support of 32-bit XFS quotactl over 64bit OS in next patch.
Thank you!
|
|
|
|
| Re: [PATCH] diskquota: 32bit quota tools on 64bit architectures [message #14134 is a reply to message #7646] |
Fri, 15 June 2007 10:41 |
Vasily Tarasov
Messages: 1345
Registered: January 2006
|
Senior Member |
|
|
You can find a half-year back discussions of this patch:
First attempt: http://lkml.org/lkml/2006/10/19/123
Second attempt: http://lkml.org/lkml/2006/10/25/57
I think they will answer your questions.
Thank you,
Vasily
On Fri, 2007-06-15 at 12:03 +0200, Mikael Pettersson wrote:
> On Fri, 15 Jun 2007 13:01:48 +0400, Vasily Tarasov wrote:
> > 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:
>
> Your patch only converts ia32 on x86-64 or ia64.
> What about ppc32-on-ppc64 and sparc32-on-sparc64?
> And, I guess, mips32-on-mips64?
>
> > --- linux-2.6.22-rc4-fixed/fs/quota.c.orig 2007-06-14 15:55:26.000000000 +0400
> > +++ linux-2.6.22-rc4-fixed/fs/quota.c 2007-06-14 19:50:13.000000000 +0400
> ...
> > +#if defined(CONFIG_X86_64) || defined(CONFIG_IA64)
> > +/*
> > + * This code works only for 32 bit quota tools over 64 bit OS (x86_64, ia64)
> > + * and is necessary due to alignment problems.
> > + */
>
> The #ifdef looks way too arch-specific. And isn't there a shared
> compat.c module somewhere that this should go into?
>
> /Mikael
|
|
|
|
| Re: [PATCH] diskquota: 32bit quota tools on 64bit architectures [message #14135 is a reply to message #7646] |
Fri, 15 June 2007 11:00 |
Vasily Tarasov
Messages: 1345
Registered: January 2006
|
Senior Member |
|
|
On Fri, 2007-06-15 at 12:43 +0200, Arnd Bergmann wrote:
> On Friday 15 June 2007, Mikael Pettersson wrote:
> > > --- linux-2.6.22-rc4-fixed/fs/quota.c.orig 2007-06-14 15:55:26.000000000 +0400
> > > +++ linux-2.6.22-rc4-fixed/fs/quota.c 2007-06-14 19:50:13.000000000 +0400
> > ...
> > > +#if defined(CONFIG_X86_64) || defined(CONFIG_IA64)
> > > +/*
> > > + * This code works only for 32 bit quota tools over 64 bit OS (x86_64, ia64)
> > > + * and is necessary due to alignment problems.
> > > + */
> >
> > The #ifdef looks way too arch-specific. And isn't there a shared
> > compat.c module somewhere that this should go into?
> >
>
> Only x86_64 and ia64 have this particular problem, the other architectures,
> and hopefully all future 64 bit platforms with 32 bit user space use
> the same alignment rules in elf32 and elf64.
>
> Still, the patch should be converted to use the compat_u64 type and not
> add an 'attribute((packed))' so that you _can_ use the same code on all
> architectures. See my 'Introduce compat_u64 and compat_s64 types' patch
> that I just posted in another thread.
>
> Arnd <><
>
Agree, it'll be the most clean solution.
Is it ok, if I'll send a patch against (current kernel + Arnd's patch)?
Thanks,
Vasily
|
|
|
|
|
|
|
|
| Re: [PATCH] diskquota: 32bit quota tools on 64bit architectures [message #14143 is a reply to message #7646] |
Fri, 15 June 2007 11:08 |
Mikael Pettersson
Messages: 3
Registered: June 2007
|
Junior Member |
|
|
On Fri, 15 Jun 2007 12:43:01 +0200, Arnd Bergmann wrote:
> On Friday 15 June 2007, Mikael Pettersson wrote:
> > > --- linux-2.6.22-rc4-fixed/fs/quota.c.orig=A0=A0=A0=A02007-06-14 15:55:=
> 26.000000000 +0400
> > > +++ linux-2.6.22-rc4-fixed/fs/quota.c=A02007-06-14 19:50:13.000000000 +=
> 0400
> > ...
> > > +#if defined(CONFIG_X86_64) || defined(CONFIG_IA64)
> > > +/*
> > > + * This code works only for 32 bit quota tools over 64 bit OS (x86_64,=
> ia64)
> > > + * and is necessary due to alignment problems.
> > > + */
> >=20
> > The #ifdef looks way too arch-specific. And isn't there a shared
> > compat.c module somewhere that this should go into?
> >=20
>
> Only x86_64 and ia64 have this particular problem, the other architectures,
> and hopefully all future 64 bit platforms with 32 bit user space use
> the same alignment rules in elf32 and elf64.
Ah yes, alignof(u64) is the same in 32- and 64-bit modes on !x86,
thus they don't have a problem here.
Thanks for explaining that. I consider this is an essential
piece of information that should be included in the patch.
(In a comment in the code, not buried in some commit log.)
/Mikael
|
|
|
|
| Re: [PATCH] diskquota: 32bit quota tools on 64bit architectures [message #14152 is a reply to message #14141] |
Fri, 15 June 2007 14:48 |
Vasily Tarasov
Messages: 1345
Registered: January 2006
|
Senior Member |
|
|
On Fri, 2007-06-15 at 12:43 +0200, Arnd Bergmann wrote:
> On Friday 15 June 2007, Mikael Pettersson wrote:
> > > --- linux-2.6.22-rc4-fixed/fs/quota.c.orig 2007-06-14 15:55:26.000000000 +0400
> > > +++ linux-2.6.22-rc4-fixed/fs/quota.c 2007-06-14 19:50:13.000000000 +0400
> > ...
> > > +#if defined(CONFIG_X86_64) || defined(CONFIG_IA64)
> > > +/*
> > > + * This code works only for 32 bit quota tools over 64 bit OS (x86_64, ia64)
> > > + * and is necessary due to alignment problems.
> > > + */
> >
> > The #ifdef looks way too arch-specific. And isn't there a shared
> > compat.c module somewhere that this should go into?
> >
>
> Only x86_64 and ia64 have this particular problem, the other architectures,
> and hopefully all future 64 bit platforms with 32 bit user space use
> the same alignment rules in elf32 and elf64.
>
> Still, the patch should be converted to use the compat_u64 type and not
> add an 'attribute((packed))' so that you _can_ use the same code on all
> architectures. See my 'Introduce compat_u64 and compat_s64 types' patch
> that I just posted in another thread.
>
> Arnd <><
>
Hello,
I just noticed that we can not avoid the addition of packed attribute.
Look, for example:
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;
};
sizeof(if_dqblk) = 0x48
On 32 bit: 0x44
If I replace __u64/__u32 with compat equivalents - it will not help!
alligned attribute can _only_ _increase_ the size of structure, but not
decrease it.
So we should use packed or just use the array of ints: int[2].
Vasily
|
|
|
|
|
|
| Re: [PATCH] diskquota: 32bit quota tools on 64bit architectures [message #14176 is a reply to message #14153] |
Mon, 18 June 2007 07:41 |
Vasily Tarasov
Messages: 1345
Registered: January 2006
|
Senior Member |
|
|
On Fri, 2007-06-15 at 17:24 +0200, Arnd Bergmann wrote:
> On Friday 15 June 2007, Vasily Tarasov wrote:
> > I just noticed that we can not avoid the addition of packed attribute.
> > Look, for example:
> >
> > 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;
> > };
> >
> > sizeof(if_dqblk) = 0x48
> > On 32 bit: 0x44
> >
> > If I replace __u64/__u32 with compat equivalents - it will not help!
> > alligned attribute can _only_ _increase_ the size of structure, but not
> > decrease it.
>
> No, the gcc documentation isn't quite clear there, see the discussion about
> compat_u64 and compat_s64 types. It actually does the right thing when
> you use 'typedef __u64 __attribute__((aligned(64))) compat_64', as my
> patch does.
>
> Arnd <><
>
Wow!... Thank you for the explanation.
I'll resend the patch soon.
Vasily
|
|
|
|
Goto Forum:
Current Time: Tue Jul 16 13:59:51 GMT 2024
Total time taken to generate the page: 0.02915 seconds
|
OpenVZ Forum
Members
Search
Help
Register
Login
Home
