On Thu, 2008-01-31 at 08:10 -0800, Nicholas A. Bellinger wrote: > On Thu, 2008-01-31 at 09:34 -0600, James Bottomley wrote: > > On Thu, 2008-01-31 at 06:10 -0800, Nicholas A. Bellinger wrote: > > > Greetings Geert and Co, > > > > > > I have a related patch that I have been using with ps3rom.c for some > > > time that fixes a bug in fs/bio.c that assumes 512 byte sectors for > > > ATAPI operations. This bug actually exists for all non 512 byte sector > > > devices go through this code path (I found it with > > > scsi_execute_async()), but I first ran into this issue with ps3rom.c > > > because max_sectors (32) is small enough to trigger the bug assuming 512 > > > byte sectors during typical ATAPI READ_10 ops with iSCSI/HD. Because > > > typical max_sector settings for libata and USB are much higher, I have > > > never ran into this issue outside of ps3rom.c, but the bug exists > > > nevertheless.. > > > > > > The current patch assumes 512 byte sectors, and adds a sector_size > > > parameter to drivers/scsi/scsi_lib.c:scsi_req_map_sg() to change it for > > > passed struct request. I know that some folks talked about killing > > > scsi_execute_async() and fixing this problem elsewhere, but until then > > > please consider this patch. Any input is also appreciated. > > > > My first reaction is really, no; there's no way we should be doing such > > a nasty layering violation. > > > > I don't care for it either, but without this patch (or something > similar) all SCSI targets that use scsi_execute_async(), for non 512 > byte requests are broken. This causes a problem when a small max_sector > is correctly used by the LLD, and trips the check in > fs/bio.c:__bio_add_page() > > if (((bio->bi_size + len) >> 9) > max_sectors) > Could we rewind this discussion back to an actual problem description then, please? Nothing in the standard path for a CD/DVD should be using scsi_execute_async(), what's the actual problem use case? James - To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
