[Ocfs2-devel] [PATCH v2 00/24] Delete CURRENT_TIME and CURRENT_TIME_SEC macros

[Ocfs2-devel] [PATCH v2 00/24] Delete CURRENT_TIME and CURRENT_TIME_SEC macros

[Deepa Dinamani]

The series is aimed at getting rid of CURRENT_TIME and CURRENT_TIME_SEC macros.
The macros are not y2038 safe. There is no plan to transition them into being
y2038 safe.
ktime_get_* api's can be used in their place. And, these are y2038 safe.

Thanks to Arnd Bergmann for all the guidance and discussions.

Patches 2-4 were mostly generated using coccinelle scripts.

All filesystem timestamps use current_fs_time() for right granularity as
mentioned in the respective commit texts of patches. This has a changed
signature, renamed to current_time() and moved to the fs/inode.c.

This series also serves as a preparatory series to transition vfs to 64 bit
timestamps as outlined here: https://lkml.org/lkml/2016/2/12/104 .

As per Linus's suggestion in https://lkml.org/lkml/2016/5/24/663 , all the
inode timestamp changes have been squashed into a single patch. Also,
current_time() now is used as a single generic vfs filesystem timestamp api.
It also takes struct inode* as argument instead of struct super_block*.
Posting all patches together in a bigger series so that the big picture is
clear.

As per the suggestion in https://lwn.net/Articles/672598/, CURRENT_TIME macro
bug fixes are being handled in a series separate from transitioning vfs to use.

Changes from v1:
* Change current_fs_time(struct super_block *) to current_time(struct inode *)

* Note that change to add time64_to_tm() is already part of John's
  kernel tree: https://lkml.org/lkml/2016/6/17/875 .

Deepa Dinamani (24):
  vfs: Add current_time() api
  fs: Replace CURRENT_TIME with current_time() for inode timestamps
  fs: Replace CURRENT_TIME_SEC with current_time() for inode timestamps
  fs: Replace current_fs_time() with current_time()
  fs: jfs: Replace CURRENT_TIME_SEC by current_time()
  fs: ext4: Use current_time() for inode timestamps
  fs: ubifs: Replace CURRENT_TIME_SEC with current_time
  fs: btrfs: Use ktime_get_real_ts for root ctime
  fs: udf: Replace CURRENT_TIME with current_time()
  fs: cifs: Replace CURRENT_TIME by current_time()
  fs: cifs: Replace CURRENT_TIME with ktime_get_real_ts()
  fs: cifs: Replace CURRENT_TIME by get_seconds
  fs: f2fs: Use ktime_get_real_seconds for sit_info times
  drivers: staging: lustre: Replace CURRENT_TIME with current_time()
  fs: ocfs2: Use time64_t to represent orphan scan times
  fs: ocfs2: Replace CURRENT_TIME with ktime_get_real_seconds()
  audit: Use timespec64 to represent audit timestamps
  fs: nfs: Make nfs boot time y2038 safe
  fnic: Use time64_t to represent trace timestamps
  block: Replace CURRENT_TIME with ktime_get_real_ts
  libceph: Replace CURRENT_TIME with ktime_get_real_ts
  fs: ceph: Replace current_fs_time for request stamp
  time: Delete CURRENT_TIME_SEC and CURRENT_TIME macro
  time: Delete current_fs_time() function

 arch/powerpc/platforms/cell/spufs/inode.c          |  2 +-
 arch/s390/hypfs/inode.c                            |  4 ++--
 drivers/block/rbd.c                                |  2 +-
 drivers/char/sonypi.c                              |  2 +-
 drivers/infiniband/hw/qib/qib_fs.c                 |  2 +-
 drivers/misc/ibmasm/ibmasmfs.c                     |  2 +-
 drivers/oprofile/oprofilefs.c                      |  2 +-
 drivers/platform/x86/sony-laptop.c                 |  2 +-
 drivers/scsi/fnic/fnic_trace.c                     |  4 ++--
 drivers/scsi/fnic/fnic_trace.h                     |  2 +-
 drivers/staging/lustre/lustre/llite/llite_lib.c    | 16 ++++++-------
 drivers/staging/lustre/lustre/llite/namei.c        |  4 ++--
 drivers/staging/lustre/lustre/mdc/mdc_reint.c      |  6 ++---
 .../lustre/lustre/obdclass/linux/linux-obdo.c      |  6 ++---
 drivers/staging/lustre/lustre/obdclass/obdo.c      |  6 ++---
 drivers/staging/lustre/lustre/osc/osc_io.c         |  2 +-
 drivers/usb/core/devio.c                           | 18 +++++++-------
 drivers/usb/gadget/function/f_fs.c                 |  8 +++----
 drivers/usb/gadget/legacy/inode.c                  |  2 +-
 fs/9p/vfs_inode.c                                  |  2 +-
 fs/adfs/inode.c                                    |  2 +-
 fs/affs/amigaffs.c                                 |  6 ++---
 fs/affs/inode.c                                    |  2 +-
 fs/attr.c                                          |  2 +-
 fs/autofs4/inode.c                                 |  2 +-
 fs/autofs4/root.c                                  |  6 ++---
 fs/bad_inode.c                                     |  2 +-
 fs/bfs/dir.c                                       | 14 +++++------
 fs/binfmt_misc.c                                   |  2 +-
 fs/btrfs/file.c                                    |  6 ++---
 fs/btrfs/inode.c                                   | 22 ++++++++---------
 fs/btrfs/ioctl.c                                   |  8 +++----
 fs/btrfs/root-tree.c                               |  3 ++-
 fs/btrfs/transaction.c                             |  4 ++--
 fs/btrfs/xattr.c                                   |  2 +-
 fs/ceph/file.c                                     |  4 ++--
 fs/ceph/inode.c                                    |  2 +-
 fs/ceph/mds_client.c                               |  4 +++-
 fs/ceph/xattr.c                                    |  2 +-
 fs/cifs/cifsencrypt.c                              |  4 +++-
 fs/cifs/cifssmb.c                                  | 10 ++++----
 fs/cifs/file.c                                     |  4 ++--
 fs/cifs/inode.c                                    | 28 ++++++++++++----------
 fs/coda/dir.c                                      |  2 +-
 fs/coda/file.c                                     |  2 +-
 fs/coda/inode.c                                    |  2 +-
 fs/configfs/inode.c                                |  6 ++---
 fs/debugfs/inode.c                                 |  2 +-
 fs/devpts/inode.c                                  |  6 ++---
 fs/efivarfs/inode.c                                |  2 +-
 fs/exofs/dir.c                                     |  6 ++---
 fs/exofs/inode.c                                   |  4 ++--
 fs/exofs/namei.c                                   |  6 ++---
 fs/ext2/acl.c                                      |  2 +-
 fs/ext2/dir.c                                      |  6 ++---
 fs/ext2/ialloc.c                                   |  2 +-
 fs/ext2/inode.c                                    |  4 ++--
 fs/ext2/ioctl.c                                    |  4 ++--
 fs/ext2/namei.c                                    |  6 ++---
 fs/ext2/super.c                                    |  2 +-
 fs/ext2/xattr.c                                    |  2 +-
 fs/ext4/acl.c                                      |  2 +-
 fs/ext4/ext4.h                                     |  6 -----
 fs/ext4/extents.c                                  | 10 ++++----
 fs/ext4/ialloc.c                                   |  2 +-
 fs/ext4/inline.c                                   |  4 ++--
 fs/ext4/inode.c                                    |  6 ++---
 fs/ext4/ioctl.c                                    |  8 +++----
 fs/ext4/namei.c                                    | 24 ++++++++++---------
 fs/ext4/super.c                                    |  2 +-
 fs/ext4/xattr.c                                    |  2 +-
 fs/f2fs/dir.c                                      |  8 +++----
 fs/f2fs/file.c                                     |  8 +++----
 fs/f2fs/inline.c                                   |  2 +-
 fs/f2fs/namei.c                                    | 12 +++++-----
 fs/f2fs/segment.c                                  |  2 +-
 fs/f2fs/segment.h                                  |  5 ++--
 fs/f2fs/xattr.c                                    |  2 +-
 fs/fat/dir.c                                       |  2 +-
 fs/fat/file.c                                      |  6 ++---
 fs/fat/inode.c                                     |  2 +-
 fs/fat/namei_msdos.c                               | 12 +++++-----
 fs/fat/namei_vfat.c                                | 10 ++++----
 fs/fuse/control.c                                  |  2 +-
 fs/fuse/dir.c                                      |  2 +-
 fs/gfs2/bmap.c                                     |  8 +++----
 fs/gfs2/dir.c                                      | 12 +++++-----
 fs/gfs2/inode.c                                    |  8 +++----
 fs/gfs2/quota.c                                    |  2 +-
 fs/gfs2/xattr.c                                    |  8 +++----
 fs/hfs/catalog.c                                   |  8 +++----
 fs/hfs/dir.c                                       |  2 +-
 fs/hfs/inode.c                                     |  2 +-
 fs/hfsplus/catalog.c                               |  8 +++----
 fs/hfsplus/dir.c                                   |  6 ++---
 fs/hfsplus/inode.c                                 |  2 +-
 fs/hfsplus/ioctl.c                                 |  2 +-
 fs/hugetlbfs/inode.c                               | 10 ++++----
 fs/inode.c                                         | 21 +++++++++++++---
 fs/jffs2/acl.c                                     |  2 +-
 fs/jffs2/fs.c                                      |  2 +-
 fs/jfs/acl.c                                       |  2 +-
 fs/jfs/inode.c                                     |  2 +-
 fs/jfs/ioctl.c                                     |  2 +-
 fs/jfs/jfs_inode.c                                 |  2 +-
 fs/jfs/namei.c                                     | 24 +++++++++----------
 fs/jfs/super.c                                     |  2 +-
 fs/jfs/xattr.c                                     |  2 +-
 fs/kernfs/inode.c                                  |  2 +-
 fs/libfs.c                                         | 14 +++++------
 fs/locks.c                                         |  2 +-
 fs/logfs/dir.c                                     |  6 ++---
 fs/logfs/file.c                                    |  2 +-
 fs/logfs/inode.c                                   |  4 ++--
 fs/logfs/readwrite.c                               |  4 ++--
 fs/minix/bitmap.c                                  |  2 +-
 fs/minix/dir.c                                     |  6 ++---
 fs/minix/itree_common.c                            |  4 ++--
 fs/minix/namei.c                                   |  4 ++--
 fs/nfs/client.c                                    |  2 +-
 fs/nfs/netns.h                                     |  2 +-
 fs/nfs/nfs4proc.c                                  | 10 ++++----
 fs/nfs/nfs4xdr.c                                   |  2 +-
 fs/nfsd/blocklayout.c                              |  2 +-
 fs/nilfs2/dir.c                                    |  6 ++---
 fs/nilfs2/inode.c                                  |  4 ++--
 fs/nilfs2/ioctl.c                                  |  2 +-
 fs/nilfs2/namei.c                                  |  6 ++---
 fs/nsfs.c                                          |  2 +-
 fs/ntfs/inode.c                                    |  2 +-
 fs/ntfs/mft.c                                      |  2 +-
 fs/ocfs2/acl.c                                     |  2 +-
 fs/ocfs2/alloc.c                                   |  2 +-
 fs/ocfs2/aops.c                                    |  2 +-
 fs/ocfs2/cluster/heartbeat.c                       |  2 +-
 fs/ocfs2/dir.c                                     |  4 ++--
 fs/ocfs2/dlmfs/dlmfs.c                             |  4 ++--
 fs/ocfs2/file.c                                    | 12 +++++-----
 fs/ocfs2/inode.c                                   |  2 +-
 fs/ocfs2/journal.c                                 |  4 ++--
 fs/ocfs2/move_extents.c                            |  2 +-
 fs/ocfs2/namei.c                                   | 16 +++++++------
 fs/ocfs2/ocfs2.h                                   |  2 +-
 fs/ocfs2/refcounttree.c                            |  4 ++--
 fs/ocfs2/super.c                                   |  2 +-
 fs/ocfs2/xattr.c                                   |  2 +-
 fs/omfs/dir.c                                      |  4 ++--
 fs/omfs/inode.c                                    |  2 +-
 fs/openpromfs/inode.c                              |  2 +-
 fs/orangefs/file.c                                 |  2 +-
 fs/orangefs/inode.c                                |  2 +-
 fs/orangefs/namei.c                                | 10 ++++----
 fs/pipe.c                                          |  2 +-
 fs/posix_acl.c                                     |  2 +-
 fs/proc/base.c                                     |  2 +-
 fs/proc/inode.c                                    |  4 ++--
 fs/proc/proc_sysctl.c                              |  2 +-
 fs/proc/self.c                                     |  2 +-
 fs/proc/thread_self.c                              |  2 +-
 fs/pstore/inode.c                                  |  2 +-
 fs/ramfs/inode.c                                   |  6 ++---
 fs/reiserfs/inode.c                                |  2 +-
 fs/reiserfs/ioctl.c                                |  4 ++--
 fs/reiserfs/namei.c                                | 12 +++++-----
 fs/reiserfs/stree.c                                |  8 +++----
 fs/reiserfs/super.c                                |  2 +-
 fs/reiserfs/xattr.c                                |  6 ++---
 fs/reiserfs/xattr_acl.c                            |  2 +-
 fs/sysv/dir.c                                      |  6 ++---
 fs/sysv/ialloc.c                                   |  2 +-
 fs/sysv/itree.c                                    |  4 ++--
 fs/sysv/namei.c                                    |  4 ++--
 fs/tracefs/inode.c                                 |  2 +-
 fs/ubifs/dir.c                                     | 10 ++++----
 fs/ubifs/file.c                                    | 12 +++++-----
 fs/ubifs/ioctl.c                                   |  2 +-
 fs/ubifs/misc.h                                    | 10 --------
 fs/ubifs/sb.c                                      | 14 +++++++----
 fs/ubifs/xattr.c                                   |  6 ++---
 fs/udf/ialloc.c                                    |  2 +-
 fs/udf/inode.c                                     |  4 ++--
 fs/udf/namei.c                                     | 20 ++++++++--------
 fs/udf/super.c                                     |  9 +++++--
 fs/ufs/dir.c                                       |  6 ++---
 fs/ufs/ialloc.c                                    |  8 ++++---
 fs/ufs/inode.c                                     |  6 ++---
 fs/ufs/namei.c                                     |  6 ++---
 fs/xfs/xfs_acl.c                                   |  2 +-
 fs/xfs/xfs_inode.c                                 |  2 +-
 fs/xfs/xfs_iops.c                                  |  2 +-
 fs/xfs/xfs_trans_inode.c                           |  2 +-
 include/linux/audit.h                              |  4 ++--
 include/linux/fs.h                                 |  2 +-
 include/linux/time.h                               |  3 ---
 ipc/mqueue.c                                       | 18 +++++++-------
 kernel/audit.c                                     | 10 ++++----
 kernel/audit.h                                     |  2 +-
 kernel/auditsc.c                                   |  6 ++---
 kernel/bpf/inode.c                                 |  2 +-
 kernel/time/time.c                                 | 14 -----------
 mm/shmem.c                                         | 20 ++++++++--------
 net/ceph/messenger.c                               |  6 +++--
 net/ceph/osd_client.c                              |  4 ++--
 net/sunrpc/rpc_pipe.c                              |  2 +-
 security/inode.c                                   |  2 +-
 security/selinux/selinuxfs.c                       |  2 +-
 206 files changed, 533 insertions(+), 522 deletions(-)

-- 
1.9.1

Cc: adilger.kernel at dilger.ca
Cc: adrian.hunter at intel.com
Cc: anna.schumaker at netapp.com
Cc: buchino at cisco.com
Cc: ceph-devel at vger.kernel.org
Cc: clm at fb.com
Cc: cm224.lee at samsung.com
Cc: dedekind1 at gmail.com
Cc: dsterba at suse.com
Cc: elder at kernel.org
Cc: eparis at redhat.com
Cc: gregkh at linuxfoundation.org
Cc: hiralpat at cisco.com
Cc: idryomov at gmail.com
Cc: jack at suse.com
Cc: jaegeuk at kernel.org
Cc: jbacik at fb.com
Cc: jejb at linux.vnet.ibm.com
Cc: jfs-discussion at lists.sourceforge.net
Cc: jlbec at evilplan.org
Cc: john.stultz at linaro.org
Cc: linux-audit at redhat.com
Cc: linux-btrfs at vger.kernel.org
Cc: linux-ext4 at vger.kernel.org
Cc: linux-f2fs-devel at lists.sourceforge.net
Cc: linux-mtd at lists.infradead.org
Cc: linux-nfs at vger.kernel.org
Cc: linux-scsi at vger.kernel.org
Cc: lustre-devel at lists.lustre.org
Cc: martin.petersen at oracle.com
Cc: mfasheh at suse.com
Cc: ocfs2-devel at oss.oracle.com
Cc: paul at paul-moore.com
Cc: sage at redhat.com
Cc: sfrench at samba.org
Cc: shaggy at kernel.org
Cc: sramars at cisco.com
Cc: trond.myklebust at primarydata.com
Cc: zyan at redhat.com

[Ocfs2-devel] [PATCH v2 15/24] fs: ocfs2: Use time64_t to represent orphan scan times

[Deepa Dinamani]

struct timespec is not y2038 safe.
Use time64_t which is y2038 safe to represent orphan
scan times.
time64_t is sufficient here as only the seconds delta
times are relevant.

Also use appropriate time functions that return time in
time64_t format. Time functions now return monotonic
time instead of real time as only delta scan times are
relevant and these values are not persistent across
reboots.

The format string for the debug print is still using long
as this is only the time elapsed since the last scan and
long is sufficient to represent this value.

Signed-off-by: Deepa Dinamani <deepa.kernel@gmail.com>
Cc: Mark Fasheh <mfasheh@suse.com>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: ocfs2-devel at oss.oracle.com
---
 fs/ocfs2/journal.c | 4 ++--
 fs/ocfs2/ocfs2.h   | 2 +-
 fs/ocfs2/super.c   | 2 +-
 3 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/fs/ocfs2/journal.c b/fs/ocfs2/journal.c
index e607419..df76e60 100644
--- a/fs/ocfs2/journal.c
+++ b/fs/ocfs2/journal.c
@@ -1946,7 +1946,7 @@ static void ocfs2_queue_orphan_scan(struct ocfs2_super *osb)
 	 */
 	seqno++;
 	os->os_count++;
-	os->os_scantime = CURRENT_TIME;
+	os->os_scantime = ktime_get_seconds();
 unlock:
 	ocfs2_orphan_scan_unlock(osb, seqno);
 out:
@@ -2003,7 +2003,7 @@ void ocfs2_orphan_scan_start(struct ocfs2_super *osb)
 	struct ocfs2_orphan_scan *os;
 
 	os = &osb->osb_orphan_scan;
-	os->os_scantime = CURRENT_TIME;
+	os->os_scantime = ktime_get_seconds();
 	if (ocfs2_is_hard_readonly(osb) || ocfs2_mount_local(osb))
 		atomic_set(&os->os_state, ORPHAN_SCAN_INACTIVE);
 	else {
diff --git a/fs/ocfs2/ocfs2.h b/fs/ocfs2/ocfs2.h
index e63af7d..7e5958b 100644
--- a/fs/ocfs2/ocfs2.h
+++ b/fs/ocfs2/ocfs2.h
@@ -224,7 +224,7 @@ struct ocfs2_orphan_scan {
 	struct ocfs2_super 	*os_osb;
 	struct ocfs2_lock_res 	os_lockres;     /* lock to synchronize scans */
 	struct delayed_work 	os_orphan_scan_work;
-	struct timespec		os_scantime;  /* time this node ran the scan */
+	time64_t		os_scantime;  /* time this node ran the scan */
 	u32			os_count;      /* tracks node specific scans */
 	u32  			os_seqno;       /* tracks cluster wide scans */
 	atomic_t		os_state;              /* ACTIVE or INACTIVE */
diff --git a/fs/ocfs2/super.c b/fs/ocfs2/super.c
index 3971146..6992c00 100644
--- a/fs/ocfs2/super.c
+++ b/fs/ocfs2/super.c
@@ -337,7 +337,7 @@ static int ocfs2_osb_dump(struct ocfs2_super *osb, char *buf, int len)
 		out += snprintf(buf + out, len - out, "Disabled\n");
 	else
 		out += snprintf(buf + out, len - out, "%lu seconds ago\n",
-				(get_seconds() - os->os_scantime.tv_sec));
+				(unsigned long)(ktime_get_seconds() - os->os_scantime));
 
 	out += snprintf(buf + out, len - out, "%10s => %3s  %10s\n",
 			"Slots", "Num", "RecoGen");
-- 
1.9.1

[Ocfs2-devel] [PATCH v2 16/24] fs: ocfs2: Replace CURRENT_TIME with ktime_get_real_seconds()

[Deepa Dinamani]

CURRENT_TIME is not y2038 safe.

Use y2038 safe ktime_get_real_seconds() here for timestamps.

struct heartbeat_block's hb_seq and deletetion time are already
64 bits wide and accommodate times beyond y2038.

Signed-off-by: Deepa Dinamani <deepa.kernel@gmail.com>
Cc: Mark Fasheh <mfasheh@suse.com>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: ocfs2-devel at oss.oracle.com
---
 fs/ocfs2/cluster/heartbeat.c | 2 +-
 fs/ocfs2/inode.c             | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/fs/ocfs2/cluster/heartbeat.c b/fs/ocfs2/cluster/heartbeat.c
index 636abcb..9158c98 100644
--- a/fs/ocfs2/cluster/heartbeat.c
+++ b/fs/ocfs2/cluster/heartbeat.c
@@ -741,7 +741,7 @@ static inline void o2hb_prepare_block(struct o2hb_region *reg,
 	hb_block = (struct o2hb_disk_heartbeat_block *)slot->ds_raw_block;
 	memset(hb_block, 0, reg->hr_block_bytes);
 	/* TODO: time stuff */
-	cputime = CURRENT_TIME.tv_sec;
+	cputime = ktime_get_real_seconds();
 	if (!cputime)
 		cputime = 1;
 
diff --git a/fs/ocfs2/inode.c b/fs/ocfs2/inode.c
index c56a767..382401d 100644
--- a/fs/ocfs2/inode.c
+++ b/fs/ocfs2/inode.c
@@ -703,7 +703,7 @@ static int ocfs2_remove_inode(struct inode *inode,
 		goto bail_commit;
 	}
 
-	di->i_dtime = cpu_to_le64(CURRENT_TIME.tv_sec);
+	di->i_dtime = cpu_to_le64(ktime_get_real_seconds());
 	di->i_flags &= cpu_to_le32(~(OCFS2_VALID_FL | OCFS2_ORPHANED_FL));
 	ocfs2_journal_dirty(handle, di_bh);
 
-- 
1.9.1

[Ocfs2-devel] [PATCH v2 00/24] Delete CURRENT_TIME and CURRENT_TIME_SEC macros

[Linus Torvalds]

On Sun, Jun 19, 2016 at 5:26 PM, Deepa Dinamani <deepa.kernel@gmail.com> wrote:
> The series is aimed at getting rid of CURRENT_TIME and CURRENT_TIME_SEC macros.

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.

But that is entirely orthogonal to this patch-set, and should be seen
as a separate issue.

And maybe it doesn't end up helping anyway, but I do think those
"simple" direct assignments will really generate pretty disgusting
code on 32-bit architectures.

That whole

    inode->i_atime = inode->i_mtime = CURRENT_TIME;

model really made a lot more sense back in the ancient days when inode
times were just simply 32-bit seconds (not even timeval structures).

                  Linus

[Ocfs2-devel] [PATCH v2 00/24] Delete CURRENT_TIME and CURRENT_TIME_SEC macros

[Deepa Dinamani]

> 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

[Ocfs2-devel] [Y2038] [PATCH v2 00/24] Delete CURRENT_TIME and CURRENT_TIME_SEC macros

[Arnd Bergmann]

On Monday, June 20, 2016 11:03:01 AM CEST you wrote:
> On Sun, Jun 19, 2016 at 5:26 PM, Deepa Dinamani <deepa.kernel@gmail.com> wrote:
> > The series is aimed at getting rid of CURRENT_TIME and CURRENT_TIME_SEC macros.

> 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.

I guess we already have that today, as the implementation of
current_fs_time() is

static inline struct timespec64 tk_xtime(struct timekeeper *tk)
{
        struct timespec64 ts;

        ts.tv_sec = tk->xtime_sec;
        ts.tv_nsec = (long)(tk->tkr_mono.xtime_nsec >> tk->tkr_mono.shift);
        return ts;
}
extern struct timespec64 current_kernel_time64(void);
struct timespec64 current_kernel_time64(void)
{
        struct timekeeper *tk = &tk_core.timekeeper;
        struct timespec64 now;
        unsigned long seq;

        do {
                seq = read_seqcount_begin(&tk_core.seq);

                now = tk_xtime(tk);
        } while (read_seqcount_retry(&tk_core.seq, seq));

        return now;
}
static inline struct timespec current_kernel_time(void)
{
        struct timespec64 now = current_kernel_time64();

        return timespec64_to_timespec(now);
}
extern struct timespec current_fs_time(struct super_block *sb);
struct timespec current_fs_time(struct super_block *sb)
{       
        struct timespec now = current_kernel_time();
        return timespec_trunc(now, sb->s_time_gran);
}       

We can surely do a little better than this, independent of the
conversion in Deepa's patch set.

> 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.
> 
> But that is entirely orthogonal to this patch-set, and should be seen
> as a separate issue.

I've played around with that, but found it hard to avoid going
through memory other than going all the way to the tk_xtime()
access to copy both tk->xtime_sec and the nanoseconds into
the inode fields.

Without that, the set_inode_time() implementation ends up
being more expensive than
inode->i_atime = inode->i_ctime = inode->i_mtime = current_time(inode);
because we still copy through the stack but also have
a couple of conditional branches that we don't have at the
moment.

At the moment, the triple assignment becomes (here on ARM)

   c:   4668            mov     r0, sp
  12:   f7ff fffe       bl      0 <current_kernel_time64>
  3e:   f107 0520       add.w   r5, r7, #32
                        12: R_ARM_THM_CALL      current_kernel_time64
  16:   f106 0410       add.w   r4, r6, #16
  1a:   e89d 000f       ldmia.w sp, {r0, r1, r2, r3} # load from stack
  1e:   e885 000f       stmia.w r5, {r0, r1, r2, r3} # store into i_atime
  22:   e884 000f       stmia.w r4, {r0, r1, r2, r3} #            i_ctime
  26:   e886 000f       stmia.w r6, {r0, r1, r2, r3} #            i_mtime

and a slightly more verbose version of the same thing on x86
(storing only 12 bytes instead of 16 is cheaper there, while
ARM does a store-multiple to copy the entire structure).

        Arnd

[Ocfs2-devel] [Y2038] [PATCH v2 00/24] Delete CURRENT_TIME and CURRENT_TIME_SEC macros

[Arnd Bergmann]

On Sunday, June 19, 2016 5:26:59 PM CEST Deepa Dinamani wrote:
> The series is aimed at getting rid of CURRENT_TIME and CURRENT_TIME_SEC macros.
> The macros are not y2038 safe. There is no plan to transition them into being
> y2038 safe.
> ktime_get_* api's can be used in their place. And, these are y2038 safe.
> 
> Thanks to Arnd Bergmann for all the guidance and discussions.
> 
> Patches 2-4 were mostly generated using coccinelle scripts.
> 
> All filesystem timestamps use current_fs_time() for right granularity as
> mentioned in the respective commit texts of patches. This has a changed
> signature, renamed to current_time() and moved to the fs/inode.c.
> 
> This series also serves as a preparatory series to transition vfs to 64 bit
> timestamps as outlined here: https://lkml.org/lkml/2016/2/12/104 .
> 
> As per Linus's suggestion in https://lkml.org/lkml/2016/5/24/663 , all the
> inode timestamp changes have been squashed into a single patch. Also,
> current_time() now is used as a single generic vfs filesystem timestamp api.
> It also takes struct inode* as argument instead of struct super_block*.
> Posting all patches together in a bigger series so that the big picture is
> clear.
> 
> As per the suggestion in https://lwn.net/Articles/672598/, CURRENT_TIME macro
> bug fixes are being handled in a series separate from transitioning vfs to use.

I've looked in detail at all the patches in this version now, and while
overall everything is fine, I found that two patches cannot be part of the
series because of the dependency on the patch that John already took (adding
time64_to_tm), but I think that's ok because we just need to change over
all the users of CURRENT_TIME and CURRENT_TIME_SEC that assign to inode
timestamps in order to prepare for the type change, the other ones
can be changed later.

I also found a few things that could be done differently to make the
later conversion slightly easier, but it's also possible that I missed
part of your bigger plan for those files, and none of them seem important.

	Arnd