On 02/01/2012 08:15 PM, Martin K. Petersen wrote: >>>>>> "James" == James Bottomley <James.Bottomley@xxxxxxxxxxxxxxxxxxxxx> writes: > > IOW, the filesystem should only ever act as a conduit. The only real > challenge as far as I can tell is how to handle concurrent protected and > unprotected updates to a page. If a non-PI-aware app updates a cached > page which is subsequently read by an app requesting PI that means we > may have to force a write-out followed by a read to get valid PI. We > could synthesize it to avoid the I/O but I think that would be violating > the premise of protected transfer. Another option is to have an > exclusive write access mechanism that only permits either protected or > unprotected access to a page. Yes. a protected write implies a byte-range locking on the file. (And can be implemented with one) Also the open() call demands an O_PROTECT option. Protection is then a file attribute as well. > Boaz -- 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
