submit_bio() flush to disk immediately

[Rajat Sharma]

On Tue, Aug 6, 2013 at 1:20 PM, Prashant Shah <pshah.mumbai at gmail.com> wrote:
> Hi,
>
> On Tue, Aug 6, 2013 at 1:15 PM, Rajat Sharma <fs.rajat at gmail.com> wrote:
>> How are you reading and writing? What is your test utility? 'dd' has
>> an option to specify iflag/oflag=direct, which would bypass buffer
>> cache. But anyways this problem should not happen even if data is
>> written to cache, you should read it back from cache.
>
> I am using cat command. Its a block that belongs to a file and I am
> directly writing to the block. On reading the file I am getting stale
> data.
>
Most likely you are getting stale data from filesystem page-cache.
Please don't use cat, use dd with iflag/oflag=direct.

> Regards.

-Rajat