[PATCH 1/3] block: add 'read_keys' persistent reservation ioctl

Hannes Reinecke
2025-06-03T10:06:05Z

The persistent reservation operations already have a callback for
'read_keys', but this is not accessible via an ioctl (unlike the
other callbacks). So add a new persistent reservation ioctl 'READ_KEYS'
to allow userspace to use this functionality.

Signed-off-by: Hannes Reinecke <hare@kernel.org>
---
block/ioctl.c | 39 +++++++++++++++++++++++++++++++++++++++
include/linux/pr.h | 6 ------
include/uapi/linux/pr.h | 7 +++++++
3 files changed, 46 insertions(+), 6 deletions(-)

diff --git a/block/ioctl.c b/block/ioctl.c
index e472cc1030c6..71f87974e044 100644
--- a/block/ioctl.c
+++ b/block/ioctl.c
@@ -422,6 +422,43 @@ static int blkdev_pr_clear(struct block_device *bdev, blk_mode_t mode,
return ops->pr_clear(bdev, c.key);
}

+static int blkdev_pr_read_keys(struct block_device *bdev, blk_mode_t mode,
+ struct pr_keys __user *arg)
+{
+ const struct pr_ops *ops = bdev->bd_disk->fops->pr_ops;
+ struct pr_keys k_in, *k_out;
+ size_t k_len;
+ int ret, num_keys;
+
+ if (!blkdev_pr_allowed(bdev, mode))
+ return -EPERM;
+ if (!ops || !ops->pr_read_keys)
+ return -EOPNOTSUPP;
+
+ if (copy_from_user(&k_in, arg, sizeof(k_in)))
+ return -EFAULT;
+
+ num_keys = k_in.num_keys;
+ k_out = kzalloc(sizeof(struct pr_keys) + num_keys * sizeof(u64),
+ GFP_KERNEL);
+ if (!k_out)
+ return -ENOMEM;
+
+ k_out->num_keys = num_keys;
+ ret = ops->pr_read_keys(bdev, k_out);
+ if (ret) {
+ kfree(k_out);
+ return ret;
+ }
+
+ k_len = sizeof(k_in) + num_keys * sizeof(u64);
+ if (copy_to_user(arg, k_out, k_len))
+ ret = -EFAULT;
+
+ kfree(k_out);
+ return ret;
+}
+
static int blkdev_flushbuf(struct block_device *bdev, unsigned cmd,
unsigned long arg)
{
@@ -643,6 +680,8 @@ static int blkdev_common_ioctl(struct block_device *bdev, blk_mode_t mode,
return blkdev_pr_preempt(bdev, mode, argp, true);
case IOC_PR_CLEAR:
return blkdev_pr_clear(bdev, mode, argp);
+ case IOC_PR_READ_KEYS:
+ return blkdev_pr_read_keys(bdev, mode, argp);
default:
return -ENOIOCTLCMD;
}
diff --git a/include/linux/pr.h b/include/linux/pr.h
index 3003daec28a5..6f293c3e27a1 100644
--- a/include/linux/pr.h
+++ b/include/linux/pr.h
@@ -4,12 +4,6 @@

#include <uapi/linux/pr.h>

-struct pr_keys {
- u32 generation;
- u32 num_keys;
- u64 keys[];
-};
-
struct pr_held_reservation {
u64 key;
u32 generation;
diff --git a/include/uapi/linux/pr.h b/include/uapi/linux/pr.h
index d8126415966f..6e0d91d43c54 100644
--- a/include/uapi/linux/pr.h
+++ b/include/uapi/linux/pr.h
@@ -56,6 +56,12 @@ struct pr_clear {
__u32 __pad;
};

+struct pr_keys {
+ __u32 generation;
+ __u32 num_keys;
+ __u64 keys[];
+};
+
#define PR_FL_IGNORE_KEY (1 << 0) /* ignore existing key */

#define IOC_PR_REGISTER _IOW('p', 200, struct pr_registration)
@@ -64,5 +70,6 @@ struct pr_clear {
#define IOC_PR_PREEMPT _IOW('p', 203, struct pr_preempt)
#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_keys)

#endif /* _UAPI_PR_H */
--
2.35.3