The Record Lock Record

In this example we investigate the RLR and how it records a locked range within a file. We will also see how the Block-Id of a thread waiting for access to a locked file range directly leads to discovery of the RLR.

We introduce the RLR by showing its relationship to other file-system control blocks in the following diagram. This depicts the following situation:

• Three processes have opened the same file, in the order process 1, 2, then 3.

• The MFT heads the chain of SFTs, each representing an open instance of the same file. The MFT points to the most recent SFT open instance.

• Process 1 and process 2 have each locked a range within the same file. RLRs 1 and 2 correspond to process 1 and 2.

• The MFT heads the chain of RLRs starting with the most recent. The pointer from the MFT (lptr) is the offset within the RLR segment.