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Re: [PATCH v2 00/24] Delete CURRENT_TIME and CURRENT_TIME_SEC macros

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> This version now looks ok to me.
>
> I do have a comment (or maybe just a RFD) for future work.
>
> It does strike me that once we actually change over the inode times to
> use timespec64, the calling conventions are going to be fairly
> horrendous on most 32-bit architectures.
>
> Gcc handles 8-byte structure returns (on most architectures) by
> returning them as two 32-bit registers (%edx:%eax on x86). But once it
> is timespec64, that will no longer be the case, and the calling
> convention will end up using a pointer to the local stack instead.
>
> So for 32-bit code generation, we *may* want to introduce a new model of doing
>
>     set_inode_time(inode, ATTR_ATIME | ATTR_MTIME);
>
> which basically just does
>
>     inode->i_atime = inode->i_mtime = current_time(inode);
>
> but with a much easier calling convention on 32-bit architectures.

Arnd and I had discussed something like this before.
But, for entirely different reasons:

Having the set_inode_time() like you suggest will also help switching
of vfs inode times to timespec64.
We were suggesting all the accesses to inode time be abstracted
through something like inode_set_time().
Arnd also had suggested a split representation of fields in the struct
inode as well which led to space savings
as well. And, having the split representation also meant no more
direct assignments:

https://lkml.org/lkml/2016/1/7/20

This in general will be similar to setattr_copy(), but only sets times
rather than other attributes as well.

If this is what is preferred, then the patches to change vfs to use
timespec64 could make use of this and will
need to be refactored. So maybe it would be good to discuss before I
post those patches.

-Deepa

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[PATCH v2 00/24] Delete CURRENT_TIME and CURRENT_TIME_SEC macros Deepa Dinamani <deepa.kernel@gmail.com> - 2016-06-20 02:30 +0200
  [PATCH v2 10/24] fs: cifs: Replace CURRENT_TIME by current_time() Deepa Dinamani <deepa.kernel@gmail.com> - 2016-06-20 02:30 +0200
  [PATCH v2 09/24] fs: udf: Replace CURRENT_TIME with current_time() Deepa Dinamani <deepa.kernel@gmail.com> - 2016-06-20 02:30 +0200
    Re: [Y2038] [PATCH v2 09/24] fs: udf: Replace CURRENT_TIME with current_time() Arnd Bergmann <arnd@arndb.de> - 2016-06-22 16:10 +0200
      Re: [Y2038] [PATCH v2 09/24] fs: udf: Replace CURRENT_TIME with current_time() Deepa Dinamani <deepa.kernel@gmail.com> - 2016-06-23 04:00 +0200
  [PATCH v2 07/24] fs: ubifs: Replace CURRENT_TIME_SEC with current_time Deepa Dinamani <deepa.kernel@gmail.com> - 2016-06-20 02:30 +0200
    Re: [PATCH v2 07/24] fs: ubifs: Replace CURRENT_TIME_SEC with current_time Arnd Bergmann <arnd@arndb.de> - 2016-06-22 15:50 +0200
  [PATCH v2 01/24] vfs: Add current_time() api Deepa Dinamani <deepa.kernel@gmail.com> - 2016-06-20 02:30 +0200
  [PATCH v2 06/24] fs: ext4: Use current_time() for inode timestamps Deepa Dinamani <deepa.kernel@gmail.com> - 2016-06-20 02:30 +0200
    Re: [PATCH v2 06/24] fs: ext4: Use current_time() for inode timestamps Arnd Bergmann <arnd@arndb.de> - 2016-06-22 15:40 +0200
  [PATCH v2 11/24] fs: cifs: Replace CURRENT_TIME with ktime_get_real_ts() Deepa Dinamani <deepa.kernel@gmail.com> - 2016-06-20 02:40 +0200
  [PATCH v2 05/24] fs: jfs: Replace CURRENT_TIME_SEC by current_time() Deepa Dinamani <deepa.kernel@gmail.com> - 2016-06-20 02:40 +0200
    Re: [Jfs-discussion] [PATCH v2 05/24] fs: jfs: Replace  CURRENT_TIME_SEC by current_time() Dave Kleikamp <dave.kleikamp@oracle.com> - 2016-06-20 21:20 +0200
  [PATCH v2 24/24] time: Delete current_fs_time() function Deepa Dinamani <deepa.kernel@gmail.com> - 2016-06-20 02:40 +0200
  [PATCH v2 23/24] time: Delete CURRENT_TIME_SEC and CURRENT_TIME macro Deepa Dinamani <deepa.kernel@gmail.com> - 2016-06-20 02:40 +0200
    Re: [PATCH v2 23/24] time: Delete CURRENT_TIME_SEC and CURRENT_TIME macro Arnd Bergmann <arnd@arndb.de> - 2016-06-22 17:50 +0200
  [PATCH v2 08/24] fs: btrfs: Use ktime_get_real_ts for root ctime Deepa Dinamani <deepa.kernel@gmail.com> - 2016-06-20 02:40 +0200
    Re: [PATCH v2 08/24] fs: btrfs: Use ktime_get_real_ts for root ctime David Sterba <dsterba@suse.cz> - 2016-06-20 11:50 +0200
  [PATCH v2 04/24] fs: Replace current_fs_time() with current_time() Deepa Dinamani <deepa.kernel@gmail.com> - 2016-06-20 02:40 +0200
  [PATCH v2 18/24] fs: nfs: Make nfs boot time y2038 safe Deepa Dinamani <deepa.kernel@gmail.com> - 2016-06-20 02:50 +0200
  [PATCH v2 16/24] fs: ocfs2: Replace CURRENT_TIME with ktime_get_real_seconds() Deepa Dinamani <deepa.kernel@gmail.com> - 2016-06-20 02:50 +0200
  [PATCH v2 22/24] fs: ceph: Replace current_fs_time for request stamp Deepa Dinamani <deepa.kernel@gmail.com> - 2016-06-20 02:50 +0200
  [PATCH v2 17/24] audit: Use timespec64 to represent audit timestamps Deepa Dinamani <deepa.kernel@gmail.com> - 2016-06-20 02:50 +0200
    Re: [PATCH v2 17/24] audit: Use timespec64 to represent audit  timestamps Richard Guy Briggs <rgb@redhat.com> - 2016-06-20 17:20 +0200
  [PATCH v2 19/24] fnic: Use time64_t to represent trace timestamps Deepa Dinamani <deepa.kernel@gmail.com> - 2016-06-20 03:30 +0200
    Re: [PATCH v2 19/24] fnic: Use time64_t to represent trace timestamps Arnd Bergmann <arnd@arndb.de> - 2016-06-22 16:10 +0200
      Re: [PATCH v2 19/24] fnic: Use time64_t to represent trace timestamps Deepa Dinamani <deepa.kernel@gmail.com> - 2016-06-23 04:00 +0200
  [PATCH v2 13/24] fs: f2fs: Use ktime_get_real_seconds for sit_info times Deepa Dinamani <deepa.kernel@gmail.com> - 2016-06-20 03:30 +0200
  [PATCH v2 14/24] drivers: staging: lustre: Replace CURRENT_TIME with current_time() Deepa Dinamani <deepa.kernel@gmail.com> - 2016-06-20 03:40 +0200
  [PATCH v2 15/24] fs: ocfs2: Use time64_t to represent orphan scan times Deepa Dinamani <deepa.kernel@gmail.com> - 2016-06-20 03:40 +0200
  [PATCH v2 21/24] libceph: Replace CURRENT_TIME with ktime_get_real_ts Deepa Dinamani <deepa.kernel@gmail.com> - 2016-06-20 03:40 +0200
  [PATCH v2 12/24] fs: cifs: Replace CURRENT_TIME by get_seconds Deepa Dinamani <deepa.kernel@gmail.com> - 2016-06-20 03:40 +0200
  [PATCH v2 20/24] block: Replace CURRENT_TIME with ktime_get_real_ts Deepa Dinamani <deepa.kernel@gmail.com> - 2016-06-20 04:40 +0200
  Re: [PATCH v2 00/24] Delete CURRENT_TIME and CURRENT_TIME_SEC macros Linus Torvalds <torvalds@linux-foundation.org> - 2016-06-20 20:10 +0200
    Re: [PATCH v2 00/24] Delete CURRENT_TIME and CURRENT_TIME_SEC macros Deepa Dinamani <deepa.kernel@gmail.com> - 2016-06-20 21:00 +0200
    Re: [Y2038] [PATCH v2 00/24] Delete CURRENT_TIME and CURRENT_TIME_SEC macros Arnd Bergmann <arnd@arndb.de> - 2016-06-21 17:10 +0200
  Re: [Y2038] [PATCH v2 00/24] Delete CURRENT_TIME and CURRENT_TIME_SEC macros Arnd Bergmann <arnd@arndb.de> - 2016-06-22 18:00 +0200

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