On 05/07/2015 10:26 AM, Christoph Hellwig wrote: > On Mon, May 04, 2015 at 10:43:01AM -0600, Ross Zwisler wrote: >>> Yes, if CONFIG_DEBUG_BLOCK_EXT_DEVT isn't set that code doesn't work at all. >> >> I can't figure out a use case that breaks when using dynamically allocated >> minors without CONFIG_DEBUG_BLOCK_EXT_DEVT. The patch that I've been testing >> against is at the bottom of this mail. >> >> Here are the minors that I get when creating a bunch of partitions using the >> current code with PMEM_MINORS=16, with CONFIG_DEBUG_BLOCK_EXT_DEVT turned off: > > FYI, your patch below works fine for me, but the original one certainly > didn't. One big difference was that it also removed the register_blkdev > call and thus assigning a major number. > assigning a major number for what? That "assigned major number" is then never used *anywhere* in the code at all until it is unregistered. All the devices come up with the dynamic (259) major the register_blkdev is just dead code. I have experimented with this a lot, I have audited the all code stack, that major is never used, when doing the: alloc_disk(0) disk->flags |= GENHD_FL_EXT_DEVT The: disk->major = X Is completely ignored and is immediately over written. The only relic of that major registration is the pmem_major global member collecting dust. Sigh, bad habits die hard, I don't really care you can keep it. Sorry for the noise. Cheers Boaz -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
