Information about FsContext

NTFSD
1

Hi all
Does anybody can tell me the exact purpose of FsContect in
FileObject? Actually i am beginner in developing File System driver. So if
anybody is having any resources regarding this then please let me know.
Thanks in advance

Regards
Saurav

2

If you are able to read the Nagar book that will help you a lot. The samples
code and documentation in WDK/IFS are also very useful.

In the file systems space FileObject->FsContext points to a File Control
Block (FCB) [also from time ot time called a Stream Control Block (SCB)]
which is a piece of data about the file [stream] common to all file objects
for the same file [stream] that belongs to the file system.

“Saurav Gupta” wrote in message news:xxxxx@ntfsd…
Hi all
Does anybody can tell me the exact purpose of FsContect in
FileObject? Actually i am beginner in developing File System driver. So if
anybody is having any resources regarding this then please let me know.
Thanks in advance

Regards
Saurav

3

It points to FSRTL_COMMON_FCB_HEADER structure, which contains the file
size values and 2 ERESOURCE locks and is used for memory mapped files and
caching.
Note that usually this “common FCB header” is a part of the larger
FS-defined FCB structure, which is 1-per-disk-file, several opens of the same
disk file will result to several file objects and only 1 FCB, your FSD must
handle this.
The ->FsContext field, so, links the file object to the FCB.

Maxim Shatskih, Windows DDK MVP
StorageCraft Corporation
xxxxx@storagecraft.com
http://www.storagecraft.com

----- Original Message -----
From: “Saurav Gupta”
To: “Windows File Systems Devs Interest List”
Sent: Friday, February 24, 2006 1:24 PM
Subject: [ntfsd] Information about FsContext

Hi all
Does anybody can tell me the exact purpose of FsContect in
FileObject? Actually i am beginner in developing File System driver. So if
anybody is having any resources regarding this then please let me know.
Thanks in advance

Regards
Saurav

—
Questions? First check the IFS FAQ at
https://www.osronline.com/article.cfm?id=17

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4

Maxim S. Shatskih wrote:

It points to FSRTL_COMMON_FCB_HEADER structure, which contains the file
size values and 2 ERESOURCE locks and is used for memory mapped files and
caching.
Note that usually this “common FCB header” is a part of the larger
FS-defined FCB structure, which is 1-per-disk-file, several opens of the same
disk file will result to several file objects and only 1 FCB, your FSD must
handle this.
The ->FsContext field, so, links the file object to the FCB.

If I may, I have a question, in which case should you hold a the
ERESOURCE locks?

–

Edouard

5

Edouard, I think you should find your answer in the Nagar book. :slight_smile:

“Edouard A.” wrote in message
news:xxxxx@ntfsd…
> Maxim S. Shatskih wrote:
>> It points to FSRTL_COMMON_FCB_HEADER structure, which contains the
>> file
>> size values and 2 ERESOURCE locks and is used for memory mapped files and
>> caching.
>> Note that usually this “common FCB header” is a part of the larger
>> FS-defined FCB structure, which is 1-per-disk-file, several opens of the
>> same
>> disk file will result to several file objects and only 1 FCB, your FSD
>> must
>> handle this.
>> The ->FsContext field, so, links the file object to the FCB.
>
> If I may, I have a question, in which case should you hold a the
> ERESOURCE locks?
>
> –
>
> Edouard
>
>

6

> If I may, I have a question, in which case should you hold a the

ERESOURCE locks?

This is the most complex thing with the FSDs :slight_smile: study the FASTFAT source to
get some idea. In short - these locks guard the file sizes.

Maxim Shatskih, Windows DDK MVP
StorageCraft Corporation
xxxxx@storagecraft.com
http://www.storagecraft.com

7

Lyndon J. Clarke wrote:

Edouard, I think you should find your answer in the Nagar book. :slight_smile:

gr8 I have it. :slight_smile:

–

Edouard