On 03/31/2013 07:44 PM, Tomas Henzl wrote: > On 03/30/2013 05:53 PM, Hannes Reinecke wrote: >> On 03/29/2013 05:32 PM, Tomas Henzl wrote: [ .. ] >>> >>> in scsi_report_lun_scan is max_lun compared with the result of scsilun_to_int, >>> but in that value is also stored the address method. This means, that we compare >>> the max_lun to a LUN 'handle' which doesn't seem to make much sense. >>> This makes that test dependent on which address method is used and not >>> only to the LUN number which is I think expected. >>> The solution is to have a new function 'scsilun_to_num', (I can send a patch) >>> or let the individual drivers set the max_lun to -1 and test for the allowed LUNs >>> in the driver. >>> >> You sure this is necessary? > > This is not directly related to your 64bit patch, I just 'used' this thread > to discuss another issue - sorry. > Yeah, and thereby decreasing the chance of getting my patchset in :-( >> >> I would like to avoid having to parse the LUN number for validity as we >> cannot guarantee this check has any meaning for the target. >> The only authoritative check can be made by the target. > > What we can do is to decode the LUN and compare it to max_lun provided by the driver, > I think that sg_luns is able to do that, so what is needed is just to follow the SAM. > > I have seen reports of problem on three different drivers connected to various > external storage, all of them having the same basic reason - the driver sets a max_lun > and then LUN comes encoded with a newer addressing method and something like this is shown > 'kernel: scsi: host 2 channel 0 id 2 lun16643 has a LUN larger than allowed by the host adapter' > > Decoding the real LUN value would fix this problem, by decoding is only meant the use in > scsi_report_lun_scan. The LUN would be stored exactly the same way as it is now. > I know we can patch the certain drivers too, but when max_lun were what the name says > - max LU number, it would fix my problem very easy. > Errm. No. Decoding LUNs is _evil_. It has only a relevance on the target, and even then it might choose to ignore it. So we cannot try to out-guess the target here. The error you're reporting is that lpfc is setting max_luns to '255', which of course is less than 16643. Increasing max_luns on lpfc to '0xFFFF' will fix your problem; nothing to do with 64-bit LUNs ... >> >> In the 64-bit context the max_luns should rather be interpreted as a >> 'max bits' setting, ie the number of _bits_ per LUN number the HBA is >> able to transport. >> But renaming 'max_luns' to 'max_bits' is a bit pointless, as it would >> break backwards compability for no real gain. >> >> So with my patchset we have a two-step LUN validation: >> - max_luns controls the max LUN number >> (read: max number of bits per LUN) which can be transported >> to the target > > This means in fact only 32 or 64 bit - so a single bit flag is enough? > No, it is not. We have SPI narrow with max_luns = 8, SPI wide with max_luns = 16, some (older) FC HBAs supporting only 8 or 16 bits LUNs, some RAID arrays supporting 32-bit LUNs etc. Cheers, Hannes -- Dr. Hannes Reinecke zSeries & Storage hare@xxxxxxx +49 911 74053 688 SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 Nürnberg GF: J. Hawn, J. Guild, F. Imendörffer, HRB 16746 (AG Nürnberg) -- 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
