| Message ID | 20230224174502.321490-2-michael.christie@oracle.com (mailing list archive) |
|---|---|
| State | Deferred |
| Headers | show |
| Series | [v4,01/18] block: Add PR callouts for read keys and reservation | expand |
On 2/24/2023 9:44 AM, Mike Christie wrote: > Add callouts for reading keys and reservations. This allows LIO to support > the READ_KEYS and READ_RESERVATION commands and will allow dm-multipath > to optimize it's error handling so it can check if it's getting an error > because there's an existing reservation or if we need to retry different > paths. > > Note: This only initially adds the struct definitions in the kernel as I'm > not sure if we wanted to export the interface to userspace yet. read_keys > and read_reservation are exactly what dm-multipath and LIO need, but for a > userspace interface we may want something like SCSI's READ_FULL_STATUS and > NVMe's report reservation commands. Those are overkill for dm/LIO and > READ_FULL_STATUS is sometimes broken for SCSI devices. > > Signed-off-by: Mike Christie <michael.christie@oracle.com> > --- Looks good. Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com> -ck
Looks good:
Reviewed-by: Christoph Hellwig <hch@lst.de>
diff --git a/include/linux/pr.h b/include/linux/pr.h index 94ceec713afe..3003daec28a5 100644 --- a/include/linux/pr.h +++ b/include/linux/pr.h @@ -4,6 +4,18 @@ #include <uapi/linux/pr.h> +struct pr_keys { + u32 generation; + u32 num_keys; + u64 keys[]; +}; + +struct pr_held_reservation { + u64 key; + u32 generation; + enum pr_type type; +}; + struct pr_ops { int (*pr_register)(struct block_device *bdev, u64 old_key, u64 new_key, u32 flags); @@ -14,6 +26,19 @@ struct pr_ops { int (*pr_preempt)(struct block_device *bdev, u64 old_key, u64 new_key, enum pr_type type, bool abort); int (*pr_clear)(struct block_device *bdev, u64 key); + /* + * pr_read_keys - Read the registered keys and return them in the + * pr_keys->keys array. The keys array will have been allocated at the + * end of the pr_keys struct, and pr_keys->num_keys must be set to the + * number of keys the array can hold. If there are more than can fit + * in the array, success will still be returned and pr_keys->num_keys + * will reflect the total number of keys the device contains, so the + * caller can retry with a larger array. + */ + int (*pr_read_keys)(struct block_device *bdev, + struct pr_keys *keys_info); + int (*pr_read_reservation)(struct block_device *bdev, + struct pr_held_reservation *rsv); }; #endif /* LINUX_PR_H */
Add callouts for reading keys and reservations. This allows LIO to support the READ_KEYS and READ_RESERVATION commands and will allow dm-multipath to optimize it's error handling so it can check if it's getting an error because there's an existing reservation or if we need to retry different paths. Note: This only initially adds the struct definitions in the kernel as I'm not sure if we wanted to export the interface to userspace yet. read_keys and read_reservation are exactly what dm-multipath and LIO need, but for a userspace interface we may want something like SCSI's READ_FULL_STATUS and NVMe's report reservation commands. Those are overkill for dm/LIO and READ_FULL_STATUS is sometimes broken for SCSI devices. Signed-off-by: Mike Christie <michael.christie@oracle.com> --- include/linux/pr.h | 25 +++++++++++++++++++++++++ 1 file changed, 25 insertions(+)