From e2c00a44b914f652a203a42e5be27b1d99ec2eef Mon Sep 17 00:00:00 2001
From: David Milburn <dmilburn@redhat.com>
Date: Tue, 18 Dec 2018 15:36:54 -0600
Subject: [PATCH 2/2] nvme-ioctl: retrieve log pages in 4k chunks

commit 465a4d5ab209bb20ea4b3ba808438747773edd2b
Author: Hannes Reinecke <hare@suse.de>
Date:   Thu Sep 20 11:09:35 2018 +0200

    nvme-ioctl: retrieve log pages in 4k chunks

    Some log pages increase with the scale of the subsystem, so the
    overall size might be larger than the MDTS value for that controller.
    In order to avoid having to pass in the MDTS value we should restrict
    the transfer size to 4k and retrieve the log page in 4k chunks.

    Signed-off-by: Hannes Reinecke <hare@suse.com>

Signed-off-by: David Milburn <dmilburn@redhat.com>
---
 nvme-ioctl.c | 26 ++++++++++++++++++++++++--
 1 file changed, 24 insertions(+), 2 deletions(-)

diff --git a/nvme-ioctl.c b/nvme-ioctl.c
index 9cf2a33..c28a0d9 100644
--- a/nvme-ioctl.c
+++ b/nvme-ioctl.c
@@ -419,8 +419,30 @@ int nvme_get_log13(int fd, __u32 nsid, __u8 log_id, __u8 lsp, __u64 lpo,
 
 int nvme_get_log(int fd, __u32 nsid, __u8 log_id, __u32 data_len, void *data)
 {
-	return nvme_get_log13(fd, nsid, log_id, NVME_NO_LOG_LSP, NVME_NO_LOG_LPO,
-			      0, 0, data_len, data);
+	void *ptr = data;
+	__u32 offset = 0, xfer_len = data_len;
+	int ret;
+
+	/*
+	 * 4k is the smallest possible transfer unit, so by
+	 * restricting ourselves for 4k transfers we avoid having
+	 * to check the MDTS value of the controller.
+	 */
+	do {
+		xfer_len = data_len - offset;
+		if (xfer_len > 4096)
+			xfer_len = 4096;
+
+		ret = nvme_get_log13(fd, nsid, log_id, NVME_NO_LOG_LSP,
+				     offset, 0, false, xfer_len, ptr);
+		if (ret)
+			return ret;
+
+		offset += xfer_len;
+		ptr += xfer_len;
+	} while (offset < data_len);
+
+	return 0;
 }
 
 int nvme_get_telemetry_log(int fd, void *lp, int generate_report,
-- 
1.8.3.1