tree cb7dcfaa0346a06e527cd4d095d7305eda6686ad
parent bc40aee053be1c2c443e812034f41e1a3cf34752
author NeilBrown <neilb@suse.de> 1427078260 +1100
committer Al Viro <viro@zeniv.linux.org.uk> 1431666387 -0400

VFS/namei: make the use of touch_atime() in get_link() RCU-safe.

touch_atime is not RCU-safe, and so cannot be called on an RCU walk.
However, in situations where RCU-walk makes a difference, the symlink
will likely to accessed much more often than it is useful to update
the atime.

So split out the test of "Does the atime actually need to be updated"
into  atime_needs_update(), and have get_link() unlazy if it finds that
it will need to do that update.

Signed-off-by: NeilBrown <neilb@suse.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>