Does the dmsetup <dm-dev> <table-file> command, calls the constructor* * dm_ctr_fn?? If yes what are the argv passed in the dm_ctr_fn, are they the args you pass to dmsetup?? Is this constructor a callback from dm layer? when it is invoked and how it is invoked? Replies will be appreciated. Regards, satyajeet
Hi Satyajeet, On Fri, Jul 20, 2012 at 7:52 PM, Satyajeet <satya.unplugged@gmail.com>wrote:
Does the dmsetup <dm-dev> <table-file> command, calls the constructor* * dm_ctr_fn??
Yes.
If yes what are the argv passed in the dm_ctr_fn, are they the args you pass to dmsetup??
True
Is this constructor a callback from dm layer? when it is invoked and how it is invoked?
Dm layer registers a fops when ever a new device mapper target is registered. So whenever a new device is created then dm refer the fops and call the respective functions. To start learning more you can start looking into linear target's code. Regards, Gaurav Mahajan.
Replies will be appreciated.
Regards, satyajeet
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Hello Satyajeet, On Fri, Jul 20, 2012 at 7:52 PM, Satyajeet <satya.unplugged@gmail.com>wrote:
Does the dmsetup <dm-dev> <table-file> command, calls the constructor* * dm_ctr_fn??
If yes what are the argv passed in the dm_ctr_fn, are they the args you
pass to dmsetup??
Is this constructor a callback from dm layer? when it is invoked and how it is invoked?
As i understand, dmsetup create calls DM_DEVICE_CREATE which fire two ioctls 1) DM_DEV_CREATE 2) DM_TABLE_LOAD This first ioctl basically create the dev mapper device. dev_create () | -> dm_create () The second ioctl basically first creates an empty dm_table and later populate it. During the population it calls the target constructor. table_load () | dm_table_create () | populate_table () | ->dm_table_add_target () | -> ctr () For further details i would suggest you refer to dm-ioctl.c, dm.c and dm-table.c Hope it helps. -- Regards: Vineet Agarwal
Replies will be appreciated.
Regards, satyajeet
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Gaurav Mahajan -
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Vineet Agarwal