[PATCH] fs: btrfs: Use ktime_get_real_ts for root ctime

From: Deepa Dinamani
Date: Sat Oct 01 2016 - 13:24:08 EST

btrfs_root_item maintains the ctime for root updates.
This is not part of vfs_inode.

Since current_time() uses struct inode* as an argument
as Linus suggested, this cannot be used to update root
times unless, we modify the signature to use inode.

Since btrfs uses nanosecond time granularity, it can also
use ktime_get_real_ts directly to obtain timestamp for
the root. It is necessary to use the timespec time api
here because the same btrfs_set_stack_timespec_*() apis
are used for vfs inode times as well. These can be
transitioned to using timespec64 when btrfs internally
changes to use timespec64 as well.

Signed-off-by: Deepa Dinamani <deepa.kernel@xxxxxxxxx>
Cc: Chris Mason <clm@xxxxxx>
Cc: David Sterba <dsterba@xxxxxxxx>
Cc: Josef Bacik <jbacik@xxxxxx>
Cc: linux-btrfs@xxxxxxxxxxxxxxx
Changes from previous version:
* Separated from the current_time() api series.
* Moved ktime_get_real_ts() outside of spin lock.

fs/btrfs/root-tree.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/fs/btrfs/root-tree.c b/fs/btrfs/root-tree.c
index 0912960..17e5a5f 100644
--- a/fs/btrfs/root-tree.c
+++ b/fs/btrfs/root-tree.c
@@ -505,8 +505,9 @@ void btrfs_update_root_times(struct btrfs_trans_handle *trans,
struct btrfs_root *root)
struct btrfs_root_item *item = &root->root_item;
- struct timespec ct = current_fs_time(root->fs_info->sb);
+ struct timespec ct;

+ ktime_get_real_ts(&ct);
btrfs_set_root_ctransid(item, trans->transid);
btrfs_set_stack_timespec_sec(&item->ctime, ct.tv_sec);