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block: add IOC_PR_READ_KEYS ioctl

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Add a Persistent Reservations ioctl to read the list of currently
registered reservation keys. This calls the pr_ops->read_keys() 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_KEYS 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: Christoph Hellwig <hch@lst.de>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Stefan Hajnoczi
2025-12-01 16:43:28 -05:00
committed by Jens Axboe
parent 38ec8469f3
commit 22a1ffea5f
2 changed files with 63 additions and 0 deletions
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56
block/ioctl.c
View File

@@ -423,6 +423,60 @@ 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_read_keys __user *arg)
{
const struct pr_ops *ops = bdev->bd_disk->fops->pr_ops;
struct pr_keys *keys_info;
struct pr_read_keys read_keys;
u64 __user *keys_ptr;
size_t keys_info_len;
size_t keys_copy_len;
int ret;
if (!blkdev_pr_allowed(bdev, mode))
return -EPERM;
if (!ops || !ops->pr_read_keys)
return -EOPNOTSUPP;
if (copy_from_user(&read_keys, arg, sizeof(read_keys)))
return -EFAULT;
keys_info_len = struct_size(keys_info, keys, read_keys.num_keys);
if (keys_info_len == SIZE_MAX)
return -EINVAL;
keys_info = kzalloc(keys_info_len, GFP_KERNEL);
if (!keys_info)
return -ENOMEM;
keys_info->num_keys = read_keys.num_keys;
ret = ops->pr_read_keys(bdev, keys_info);
if (ret)
goto out;
/* Copy out individual keys */
keys_ptr = u64_to_user_ptr(read_keys.keys_ptr);
keys_copy_len = min(read_keys.num_keys, keys_info->num_keys) *
sizeof(keys_info->keys[0]);
if (copy_to_user(keys_ptr, keys_info->keys, keys_copy_len)) {
ret = -EFAULT;
goto out;
}
/* Copy out the arg struct */
read_keys.generation = keys_info->generation;
read_keys.num_keys = keys_info->num_keys;
if (copy_to_user(arg, &read_keys, sizeof(read_keys)))
ret = -EFAULT;
out:
kfree(keys_info);
return ret;
}
static int blkdev_flushbuf(struct block_device *bdev, unsigned cmd,
unsigned long arg)
{
@@ -645,6 +699,8 @@ 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 blk_get_meta_cap(bdev, cmd, argp);
}

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

@@ -56,6 +56,12 @@ struct pr_clear {
__u32 __pad;
};
struct pr_read_keys {
__u32 generation;
__u32 num_keys;
__u64 keys_ptr;
};
#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_read_keys)
#endif /* _UAPI_PR_H */