Re: [dm-devel] Regarding dm-linear.c

[Adam Hamsik <haaaad gmail com>]

Hi,
On Sep,Friday 12 2008, at 7:18 PM, rohit vashist wrote:

> Hi,
>
> I am currently working on device mapper and logical volume  
> manager.My question is whether dm-linear.c 's
> function linear_ctr and linear_map is called or not when we do  
> lvcreate.(or vgcreate,pvcreate).I am concentrating
> on linear mapping only.I did strace but i m not able to figure it out.

pvcreate and vgcreate are completely independent from device-mapper  
driver. Only lvcreate and other lv
commands communicates with dm driver.

I'm not linux expert :), but I think that during lvcreate only  
linear_ctr function is called. Because it allocates "linear context"  
for loaded table. Context is probably some target specific  
configuration memory
area.

linear_map is probably called only during IO. When is IO issued on  
virtual device mapped to a real
block device.

Regards

Adam.