Messages in this thread | | | Date | Sat, 20 Jun 2009 10:39:03 -0400 (EDT) | From | Alan Stern <> | Subject | Re: generic_make_request fucntion for scsi_disk |
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On Sat, 20 Jun 2009, Ravish Tayal wrote:
> Hello, > > I am debugging Filesystem code for USB mass storage devices.
What part of the filesystem code are you debugging?
Your questions talk about four separate layers: the filesystem, the block layer, the SCSI layer, and the usb-storage driver. Normally people work on only one layer at a time.
Why are you concerned with more than one layer?
> I need > help to figure out after generic_make_request how the request is > placed to scsi disk (sd) requeset queue and than how sd qeueuecommand > to usb_storeage thread. (in which context, is it system call context) > > > inside generic_make_request > > 1. q = bdev_get_queue(bio->bi_bdev); [is sd.c register queue this > queue or any other scsi file?]
See scsi_alloc_sdev() in scsi_scan.c. That's where the queue is allocated.
> 2. ret = q->make_request_fn(q, bio); [which file contain this > make_request_fn for scsi disk driver (generic)]
scsi_request_fn() is in scsi_lib.c. You could have found this out by yourself very easily with grep. sd_prep_fn() is in sd.c.
> As per my unsderanding flow is like > Fat_writepage ->_block_write_full_page --> blkdev_writepage--> > block_write_full_page-->submit_bh-->generic_make_request ??? (sd ??) > ----> queuecommand > > Please suggest any sorce file, link or document.
The most relevant source files are scsi_lib.c and scsi.c.
Alan Stern
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