[PATCH 2/3] block: add 'read_reservation' persistent reservation ioctl

Hannes Reinecke
2025-06-03T10:06:07Z

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

Signed-off-by: Hannes Reinecke <hare@kernel.org>
---
block/ioctl.c | 22 ++++++++++++++++++++++
include/linux/pr.h | 6 ------
include/uapi/linux/pr.h | 7 +++++++
3 files changed, 29 insertions(+), 6 deletions(-)

diff --git a/block/ioctl.c b/block/ioctl.c
index 71f87974e044..3612352a1d83 100644
--- a/block/ioctl.c
+++ b/block/ioctl.c
@@ -459,6 +459,26 @@ static int blkdev_pr_read_keys(struct block_device *bdev, blk_mode_t mode,
return ret;
}

+static int blkdev_pr_read_reservation(struct block_device *bdev,
+ blk_mode_t mode, struct pr_held_reservation __user *arg)
+{
+ const struct pr_ops *ops = bdev->bd_disk->fops->pr_ops;
+ struct pr_held_reservation r;
+ int ret;
+
+ if (!blkdev_pr_allowed(bdev, mode))
+ return -EPERM;
+ if (!ops || !ops->pr_read_reservation)
+ return -EOPNOTSUPP;
+
+ ret = ops->pr_read_reservation(bdev, &r);
+ if (ret)
+ return ret;
+ if (copy_to_user(arg, &r, sizeof(r)))
+ return -EFAULT;
+ return 0;
+}
+
static int blkdev_flushbuf(struct block_device *bdev, unsigned cmd,
unsigned long arg)
{
@@ -682,6 +702,8 @@ 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_RESV:
+ return blkdev_pr_read_reservation(bdev, mode, argp);
default:
return -ENOIOCTLCMD;
}
diff --git a/include/linux/pr.h b/include/linux/pr.h
index 6f293c3e27a1..e3ccfbd9dfba 100644
--- a/include/linux/pr.h
+++ b/include/linux/pr.h
@@ -4,12 +4,6 @@

#include <uapi/linux/pr.h>

-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);
diff --git a/include/uapi/linux/pr.h b/include/uapi/linux/pr.h
index 6e0d91d43c54..20198c7e68e8 100644
--- a/include/uapi/linux/pr.h
+++ b/include/uapi/linux/pr.h
@@ -62,6 +62,12 @@ struct pr_keys {
__u64 keys[];
};

+struct pr_held_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_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_keys)
+#define IOC_PR_READ_RESV _IOWR('p', 207, struct pr_held_reservation)

#endif /* _UAPI_PR_H */
--
2.35.3