[LU-3015] A typo in udmu_objs_count_estimate() causing overly conservative os_ffree values

• Type: Bug
• Resolution: Fixed
• Priority: Major
• Fix Version/s: Lustre 2.4.1, Lustre 2.5.0
• Affects Version/s: Lustre 2.4.0
• Severity: 3
• Assignee: Li Wei (Inactive)
• Reporter: Li Wei (Inactive)

Description

In this hunk from udmu_objs_count_estimate():

        est_refdblocks = (refdbytes >> SPA_MAXBLOCKSHIFT) +
                (OSD_DNODE_EST_COUNT << OSD_DNODE_EST_BLKSHIFT);
        est_usedobjs   = usedobjs + OSD_DNODE_EST_COUNT;

OSD_DNODE_EST_COUNT should be right-shifted, not left-shifted. This typo leads to a larger-than-actual dnode size estimation, which further causes overly conservative os_ffree (number of available objects) values, especially for MDTs.