One possible solution to the problem of Why does WriteFile call ReadFile and how do I avoid it?. Is to write to file using CcPreparePinWrite and PIN_CALLER_TRACKS_DIRTY_DATA. Basically what this does is to make the cache manager map a file section into memory without having to read it from disk, since the entire section is assumed to be overwritten.
The PIN_CALLER_TRACKS_DIRTY_DATA flag is commonly used in cases where a file system is managing a log file that is written to but not read from. Because the existing file data will be overwritten and not read, the cache manager may return pages of zeros instead of faulting in the actual pages of file data from disk.
This is all great in theory. Though it seems quite complicated to achieve in practice. Especially since these are kernel-mode functions that cannot be called from a user-mode application.
Is there any way to achieve this behaviour using the regular WriteFile API? Or is there any good resource that further explain how to make use of the Cache Manager Routines?
