Is it possible to preemptively provide file data?

[ZabirHoque]

ATM, I'm preemptively populating files by running a separate daemon process that touches desired files. I'm wondering if there is a more efficient way to do this?

PrjWriteFileData() seems to be the only way to provide file data to the underlying system, but its not clear to me how to derive the dataStreamId parameter when not responding to a PRJ_GET_FILE_DATA_CB callback.

[cgallred]

Placeholders can be preemptively laid down with PrjWritePlaceholderInfo/PrjWritePlaceholderInfo2, but files can't be preemptively hydrated in the same way. When a user tries to read a non-hydrated placeholder, the ProjFS file system filter driver generates a dataStreamId value, associates it with the user's FILE_OBJECT, and sends the PRJ_GET_FILE_DATA_CB callback. The hydration mechanism uses that FILE_OBJECT to write the data. There isn't currently a way to get such a FILE_OBJECT outside the regular hydration path that your daemon triggers.