FILE_NO_INTERMEDIATE_BUFFERING flag...

NTFSD
1

Hi everyone…

In my system I need to make sure that what I’ve written to the file has
reached the disk by the time when file is closed.
To secure this behavior I open file with Action=FILE_OVERWRITE_IF, and
Options=FILE_NO_INTERMEDIATE_BUFFERING | FILE_WRITE_THROUGH. To my surprise
(big surprize) file seems to be empty after writing (file size = 0).
As soon as I use Options=0 instead of FILE_NO_INTERMEDIATE_BUFFERING |
FILE_WRITE_THROUGH (and that’s the only change that
I’ve made) file has content. How FILE_NO_INTERMEDIATE_BUFFERING |
FILE_WRITE_THROUGH can cause this behavior?
I’ve observed this behavior on FAT32 volume.

TIA,

Vladimir

2

It really depends on whether the write succeeded. You did remember to
check the status of the write, right?
Remember also to supply sector aligned buffer/length - you are
essentially doing raw i/o to the block device.

Ravi

-----Original Message-----
From: Vladimir Chtchetkine [mailto:xxxxx@starbase.com]
Sent: Friday, June 07, 2002 4:17 PM
To: File Systems Developers
Subject: [ntfsd] FILE_NO_INTERMEDIATE_BUFFERING flag…

Hi everyone…
In my system I need to make sure that what I’ve written to the file has
reached the disk by the time when file is closed.
To secure this behavior I open file with Action=FILE_OVERWRITE_IF, and
Options=FILE_NO_INTERMEDIATE_BUFFERING | FILE_WRITE_THROUGH. To my
surprise (big surprize) file seems to be empty after writing (file size
= 0).
As soon as I use Options=0 instead of FILE_NO_INTERMEDIATE_BUFFERING |
FILE_WRITE_THROUGH (and that’s the only change that
I’ve made) file has content. How FILE_NO_INTERMEDIATE_BUFFERING |
FILE_WRITE_THROUGH can cause this behavior?
I’ve observed this behavior on FAT32 volume.
TIA,
Vladimir

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