Determining a sharing relationship of a file in namespace snapshots

Abstract

The technology described herein efficiently determines whether a real inode is shared among views, or owned. In-memory data structures include a view snapshot generation counter that is increased as a snapshot that generates a view is created, and an inode total weight. An in-memory virtual inode cache dataset for a filesystem object associated with the view is instantiated with the value of snapshot generation counter, sharing-related data based on the inode mapping file entry for the object, and an inode access weight. To determine whether the inode is shared (and needs to be split), such as on a write to the object, the in-memory data is evaluated. The real inode is shared if the generation counters are unequal, if the sharing-related data indicates sharing at an intermediate indirect block level, or indicates sharing at the inode level and the inode access weight is less than the inode total weight.