scsi: Add support for block PR read keys/reservation

This adds support in sd.c for the block PR read keys and read reservation
callouts, so upper layers like LIO can get the PR info that's been setup
using the existing pr callouts and return it to initiators.

Signed-off-by: Mike Christie <michael.christie@oracle.com>
Link: https://lore.kernel.org/r/20230407200551.12660-6-michael.christie@oracle.com
Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

1 files changed, 91 insertions, 0 deletions

diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
index fa3123a63f65..3e7a69eeb8f0 100644
--- a/drivers/scsi/sd.c
+++ b/drivers/scsi/sd.c
@@ -1723,6 +1723,95 @@ static int sd_scsi_to_pr_err(struct scsi_sense_hdr *sshdr, int result)
 	}
 }
 
+static int sd_pr_in_command(struct block_device *bdev, u8 sa,
+			    unsigned char *data, int data_len)
+{
+	struct scsi_disk *sdkp = scsi_disk(bdev->bd_disk);
+	struct scsi_device *sdev = sdkp->device;
+	struct scsi_sense_hdr sshdr;
+	u8 cmd[10] = { PERSISTENT_RESERVE_IN, sa };
+	const struct scsi_exec_args exec_args = {
+		.sshdr = &sshdr,
+	};
+	int result;
+
+	put_unaligned_be16(data_len, &cmd[7]);
+
+	result = scsi_execute_cmd(sdev, cmd, REQ_OP_DRV_IN, data, data_len,
+				  SD_TIMEOUT, sdkp->max_retries, &exec_args);
+	if (scsi_status_is_check_condition(result) &&
+	    scsi_sense_valid(&sshdr)) {
+		sdev_printk(KERN_INFO, sdev, "PR command failed: %d\n", result);
+		scsi_print_sense_hdr(sdev, NULL, &sshdr);
+	}
+
+	if (result <= 0)
+		return result;
+
+	return sd_scsi_to_pr_err(&sshdr, result);
+}
+
+static int sd_pr_read_keys(struct block_device *bdev, struct pr_keys *keys_info)
+{
+	int result, i, data_offset, num_copy_keys;
+	u32 num_keys = keys_info->num_keys;
+	int data_len = num_keys * 8 + 8;
+	u8 *data;
+
+	data = kzalloc(data_len, GFP_KERNEL);
+	if (!data)
+		return -ENOMEM;
+
+	result = sd_pr_in_command(bdev, READ_KEYS, data, data_len);
+	if (result)
+		goto free_data;
+
+	keys_info->generation = get_unaligned_be32(&data[0]);
+	keys_info->num_keys = get_unaligned_be32(&data[4]) / 8;
+
+	data_offset = 8;
+	num_copy_keys = min(num_keys, keys_info->num_keys);
+
+	for (i = 0; i < num_copy_keys; i++) {
+		keys_info->keys[i] = get_unaligned_be64(&data[data_offset]);
+		data_offset += 8;
+	}
+
+free_data:
+	kfree(data);
+	return result;
+}
+
+static int sd_pr_read_reservation(struct block_device *bdev,
+				  struct pr_held_reservation *rsv)
+{
+	struct scsi_disk *sdkp = scsi_disk(bdev->bd_disk);
+	struct scsi_device *sdev = sdkp->device;
+	u8 data[24] = { };
+	int result, len;
+
+	result = sd_pr_in_command(bdev, READ_RESERVATION, data, sizeof(data));
+	if (result)
+		return result;
+
+	len = get_unaligned_be32(&data[4]);
+	if (!len)
+		return 0;
+
+	/* Make sure we have at least the key and type */
+	if (len < 14) {
+		sdev_printk(KERN_INFO, sdev,
+			    "READ RESERVATION failed due to short return buffer of %d bytes\n",
+			    len);
+		return -EINVAL;
+	}
+
+	rsv->generation = get_unaligned_be32(&data[0]);
+	rsv->key = get_unaligned_be64(&data[8]);
+	rsv->type = scsi_pr_type_to_block(data[21] & 0x0f);
+	return 0;
+}
+
 static int sd_pr_out_command(struct block_device *bdev, u8 sa, u64 key,
 			     u64 sa_key, enum scsi_pr_type type, u8 flags)
 {
@@ -1804,6 +1893,8 @@ static const struct pr_ops sd_pr_ops = {
 	.pr_release	= sd_pr_release,
 	.pr_preempt	= sd_pr_preempt,
 	.pr_clear	= sd_pr_clear,
+	.pr_read_keys	= sd_pr_read_keys,
+	.pr_read_reservation = sd_pr_read_reservation,
 };
 
 static void scsi_disk_free_disk(struct gendisk *disk)