[LU-287] race in glimpse size

• Type: Bug
• Resolution: Won't Fix
• Priority: Minor
• Fix Version/s: Lustre 1.8.6
• Affects Version/s: Lustre 1.8.6
• Severity: 3
• Assignee: Niu Yawei (Inactive)
• Reporter: Niu Yawei (Inactive)

Description

It looks to me there is a race in the size glimpse:

When a client received glimpse callback, it get the lock by ldlm_handle2lock_ns() in ldlm_callback_handler(), and just before calling the ll_glimpse_callback(), this lock is happen to be canceled locally, and the kms is shrinked on cancel, then ll_glimpse_callback() will tell server a wrong size (less than actual size).

Actually, we already have a flag (i.e. LDLM_FL_KMS_IGNORE) to notify that kms is being updated because the lock is being cancelled. We could just check for this flag in ll_glimpse_callback()and return EINVAL to the glimpse. The server should then update the LVB from disk and get the right object size since kms is updated on the client once all dirty data has been pushed to the server already.

Issue Links

• Trackbacks: Lustre 1.8.x known issues tracker While testing against Lustre b18 branch, we would hit known bugs which were already reported in Lustre Bugzilla https://bugzilla.lustre.org/. In order to move away from relying on Bugzilla, we would create a JIRA