[LU-191] mdd_close will always start transaction even atime is not changed

• Type: Bug
• Resolution: Fixed
• Priority: Minor
• Fix Version/s: Lustre 2.1.0
• Affects Version/s: Lustre 2.1.0
• Severity: 3
• Assignee: Liang Zhen (Inactive)
• Reporter: Liang Zhen (Inactive)

Description

I've fixed this in bug 23289 (attachment 32253), however it's back after landing of another patch (bug 23291, attachment 31108):

• if (la->la_atime <= tmp_la->la_atime +
• mdd_obj2mdd_dev(obj)->mdd_atime_diff)
  + if (la->la_atime > tmp_la->la_atime &&
  + la->la_atime <= (tmp_la->la_atime +
  + mdd_obj2mdd_dev(obj)->mdd_atime_diff))
  la->la_valid &= ~LA_ATIME;

with this patch, the condition is always false if "la->la_atime == tmp_la->la_atime", which means even atime is exactly same as before, we still start a transaction and setattr, this will give a big impact on performance for those shortly open+close applications/tests.