Re: Persistent Reservation API V2
On Thu, Aug 20, 2015 at 11:56:36PM +, Keith Busch wrote: > NVMe can also specify > if whether or not a reservation should persist through power-loss. SCSI does as well, it's the APTPL flag. However reservations not persistent through a power loss are basically useless, so I decided to force them on in the API. From the documentation: "All implementations are expected to ensure the reservations survive a power loss" So I would prefer not to add it, or if we really have to as a negative flag to specifically opt out of the APTPL behavior. > with it. For example, NVMe can ignore existing keys when acquiring a > reservation in addition to registering a new key. This sounds like a sensible addition to me, and I wouldn't be surprised if future SPC versions will add this flag. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: Persistent Reservation API V2
On Tue, 11 Aug 2015, Christoph Hellwig wrote: This series adds support for a simplified Persistent Reservation API to the block layer. The intent is that both in-kernel and userspace consumers can use the API instead of having to hand craft SCSI or NVMe command through the various pass through interfaces. It also adds DM support as getting reservations through dm-multipath is a major pain with the current scheme. NVMe support currently isn't included as I don't have a multihost NVMe setup to test on, but Keith offered to test it and I'll have a patch for it shortly. Hi Christoph, I wrote an nvme implementation and it seems to work as expected with your pr-tests (minor modification to open an nvme target). While API appears to work as designed, there are a few features of NVMe that are unreachable with it. For example, NVMe can ignore existing keys when acquiring a reservation in addition to registering a new key. NVMe can also specify if whether or not a reservation should persist through power-loss. Anyway, I don't think SCSI has these same options. Should this new IOCTL API accommodate the common subset to maintain its simplicity, or make it more expressive for all features? The more important question might be if there are any users requiring these features, and I honestly don't know that right now. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: Persistent Reservation API V2
On 08/17/2015 01:13 PM, Christoph Hellwig wrote: Does this look fine to you Jens? I'd love to get this API into 4.3 so I can submit the NFS SCSI layout patches that depend on it for 4.4. I'll take a look at this today. -- Jens Axboe -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: Persistent Reservation API V2
Does this look fine to you Jens? I'd love to get this API into 4.3 so I can submit the NFS SCSI layout patches that depend on it for 4.4. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Persistent Reservation API V2
This series adds support for a simplified Persistent Reservation API to the block layer. The intent is that both in-kernel and userspace consumers can use the API instead of having to hand craft SCSI or NVMe command through the various pass through interfaces. It also adds DM support as getting reservations through dm-multipath is a major pain with the current scheme. NVMe support currently isn't included as I don't have a multihost NVMe setup to test on, but Keith offered to test it and I'll have a patch for it shortly. The ioctl API is documented in Documentation/block/pr.txt, but to fully understand the concept you'll have to read up the SPC spec, PRs are too complicated that trying to rephrase them into different terminology is just going to create confusion. Note that Mike wants to include the DM patches so through the DM tree, so they are only included for reference. I also have a set of simple test tools available at: git://git.infradead.org/users/hch/pr-tests.git Changes since V1: - rename DM ->ioctl to ->prepare_ioctl - rename dm_get_ioctl_table to dm_get_live_table_for_ioctl - merge two DM patches into one - various spelling fixes -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
