[LU-170] OSCC_FLAG_LOW is always set and oscc_grow_count will never grow

• Type: Bug
• Resolution: Fixed
• Priority: Blocker
• Fix Version/s: Lustre 2.1.0, Lustre 1.8.6
• Affects Version/s: Lustre 1.8.6
• Severity: 3
• Assignee: Liang Zhen (Inactive)
• Reporter: Liang Zhen (Inactive)

Description

I found osc_precreate is not working in the expected way, we always precreate 32 objects for some reason.

After digging into code I found there is a bug:

we are using req::rq_async_args.space[0] to store original value of oscc_grow_count, and using req::rq_async_args.pointer_arg[0] to store oscc, however, ptlrpc_async_args is a union, which means req::rq_async_args.space[0] will always be overwritten by a ossc (a pointer), and osc_interpret_create will always get true on this condition "if (diff < (int) req->rq_async_args.space[0])" and reset oscc_grow_count to OST_MIN_PRECREATE and set OSCC_FLAG_LOW.

The fix will be very simple but it has big impact on performance of file creation so I set priority as "major", I will post patch for it very soon.

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