Hi Nidhi, About the function call trace you can use ftrace to find out, another useful tool is scsi_logging_level to set more verbose logging output for scsi core. Regards Jack On 11/05/2013 12:48 PM, nidhi mittal hada wrote: > > Hi All > > i have got a requirement where I need to encrypt/decrypt data that goes > from scsi layer to a particular block device. > As per my understanding till now on scsi subsystem in linux, i think i > need to > use crypto api and call appropriate encrypt/decrypt function from sd > driver for block device. > > I need to locate that specific function where this change needs to be > made ... > I know basic block device driver writing in linux .. But not able to fit > scsi in this picture. > > I have few basic doubts.. kindly help in resolving ... > > 1) Now, as example block device driver sbull, as given LDD, works on > request queue, fetches req from this queue, using function req = > elv_next_request(q)), > in request function. > what is corresponding function in sd layer ? > That is the function where i have req->buffer in hand with me.. > > > 2) For a write operation from initiator to disk > is the hierarchy like this > *sd_prep_fn* > generic block device request structure -> converted into scsi specific > request structure > OR > what is scsi_prep_fn for?? > > 3)How is Scpnt pointer that is req-> special is used in sd_prep_func.. > is processed? i mean which layer picks Scpnt up and processes ?? > > 4)Any document any URL any kind of instruction will be extremely helpful. > > 5)Whenever a *new scsi device is attached *sd_probe is called > sd_async_probe() is the async part of sd_probe() So when this is called > the prep_fn is set to sd_prep_fn and hence this will be called. > > *But i thought sd_prep_fn should be called for each and every request > .....??* > Kindly help me to clear the confusion .. > > > Thanks > Nidhi > > > > > _______________________________________________ > Kernelnewbies mailing list > Kernelnewbies@xxxxxxxxxxxxxxxxx > http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies > _______________________________________________ Kernelnewbies mailing list Kernelnewbies@xxxxxxxxxxxxxxxxx http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
