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block: add IOC_PR_READ_RESERVATION ioctl 

Add a Persistent Reservations ioctl to read the current reservation.
This calls the pr_ops->read_reservation() function that was previously
added in commit c787f1baa5 ("block: Add PR callouts for read keys and
reservation") but was only used by the in-kernel SCSI target so far.

The IOC_PR_READ_RESERVATION ioctl is necessary so that userspace
applications that rely on Persistent Reservations ioctls have a way of
inspecting the current state. Cluster managers and validation tests need
this functionality.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
master
Stefan Hajnoczi 2025-12-01 16:43:29 -05:00 committed by Jens Axboe
parent 22a1ffea5f
commit 3e2cb9ee76
2 changed files with 35 additions and 0 deletions
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28
block/ioctl.c
View File

@ -477,6 +477,32 @@ out:
return ret;
}
static int blkdev_pr_read_reservation(struct block_device *bdev,
blk_mode_t mode, struct pr_read_reservation __user *arg)
{
const struct pr_ops *ops = bdev->bd_disk->fops->pr_ops;
struct pr_held_reservation rsv = {};
struct pr_read_reservation out = {};
int ret;
if (!blkdev_pr_allowed(bdev, mode))
return -EPERM;
if (!ops || !ops->pr_read_reservation)
return -EOPNOTSUPP;
ret = ops->pr_read_reservation(bdev, &rsv);
if (ret)
return ret;
out.key = rsv.key;
out.generation = rsv.generation;
out.type = rsv.type;
if (copy_to_user(arg, &out, sizeof(out)))
return -EFAULT;
return 0;
}
static int blkdev_flushbuf(struct block_device *bdev, unsigned cmd,
unsigned long arg)
{
@ -701,6 +727,8 @@ static int blkdev_common_ioctl(struct block_device *bdev, blk_mode_t mode,
return blkdev_pr_clear(bdev, mode, argp);
case IOC_PR_READ_KEYS:
return blkdev_pr_read_keys(bdev, mode, argp);
case IOC_PR_READ_RESERVATION:
return blkdev_pr_read_reservation(bdev, mode, argp);
default:
return blk_get_meta_cap(bdev, cmd, argp);
}

7
include/uapi/linux/pr.h
View File

@ -62,6 +62,12 @@ struct pr_read_keys {
__u64 keys_ptr;
};
struct pr_read_reservation {
__u64 key;
__u32 generation;
__u32 type;
};
#define PR_FL_IGNORE_KEY (1 << 0) /* ignore existing key */
#define IOC_PR_REGISTER _IOW('p', 200, struct pr_registration)
@ -71,5 +77,6 @@ struct pr_read_keys {
#define IOC_PR_PREEMPT_ABORT _IOW('p', 204, struct pr_preempt)
#define IOC_PR_CLEAR _IOW('p', 205, struct pr_clear)
#define IOC_PR_READ_KEYS _IOWR('p', 206, struct pr_read_keys)
#define IOC_PR_READ_RESERVATION _IOR('p', 207, struct pr_read_reservation)
#endif /* _UAPI_PR_H */