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How PrivateCacheMap of FILE_OBJECT looks like?

yu_shangyu_shang Member Posts: 41
edited June 2022 in NTFSD

Hi dear all,
I'm not sure how to setup PrivateCacheMap member of _FILE_OBJECT. Does it has any system implied requirements on it ? I mean something like that FCB must be started with a FSRTL_ADVANCED_FCB_HEADER. Many thanks!

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Comments

  • rod_widdowsonrod_widdowson Member - All Emails Posts: 1,239

    You set up SectionObjectPointers (along with FsContext, FsContext2) and you call CcInitalizeCacheMap at the appropriate time. Cc worries about all the rest.

    The FAT example shows how to do all this

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  • yu_shangyu_shang Member Posts: 41

    thank you. I'll try it. This doc confused me which states that this field is setup by FSD.

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  • Jason_T.Jason_T. Member Posts: 105

    @yu_shang said:
    thank you. I'll try it. This doc confused me which states that this field is setup by FSD.

    You didn't specify what type of driver you have, but the file system does own the FsContext, FsContext2, SOP, etc. If you have a normal filter (i.e. not a layered file system in a filter) then you shouldn't be setting these fields. As Rod pointed out, FAT does this, but of course it is a file system.

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  • yu_shangyu_shang Member Posts: 41
    edited June 2022

    You didn't specify what type of driver you have

    If in the context of FSD, does this mean FSD must set PrivateCacheMap up ? how ?
    BTW I've reviewed the fastfat example , found no where it will setup PrivateCacheMap.

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  • Scott_Noone_(OSR)Scott_Noone_(OSR) Administrator Posts: 3,556
    CcInitializeCacheMap set that field.

    -scott
    OSR

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  • yu_shangyu_shang Member Posts: 41
    edited June 2022

    @Scott_Noone_(OSR) said:
    CcInitializeCacheMap set that field.

    Thank you. To be a proficient driver developer. I have to debug a lot. It's really boring :smiley: .

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  • Scott_Noone_(OSR)Scott_Noone_(OSR) Administrator Posts: 3,556

    A Windows file system is a significant undertaking (years not months). Patience is key and assume that anything you write in the first 6-9 months will probably be just a learning exercise. Good luck!

    -scott
    OSR

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