nvmet: use Retain Async Event bit to clear AEN

In the current implementation, we clear the AEN bit when we get the
"get log page" command if given log page is associated with AEN.
This patch allows optionally retaining the AEN for the ctrl
under consideration when Retain Asynchronous Event (RAE) bit is set
as a part of "get log page" command.

This allows the host to read the Log page and optionally retaining the
AEN associated with this log page when using userspace tools like
nvme-cli.

Signed-off-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
[hch: also use the new helper in the just merged ANA code]
Signed-off-by: Christoph Hellwig <hch@lst.de>

drivers/nvme/target/admin-cmd.c

@@ -19,6 +19,19 @@
 #include <asm/unaligned.h>
 #include "nvmet.h"
 
+/*
+ * This helper allows us to clear the AEN based on the RAE bit,
+ * Please use this helper when processing the log pages which are
+ * associated with the AEN.
+ */
+static inline void nvmet_clear_aen(struct nvmet_req *req, u32 aen_bit)
+{
+	int rae = le32_to_cpu(req->cmd->common.cdw10[0]) & 1 << 15;
+
+	if (!rae)
+		clear_bit(aen_bit, &req->sq->ctrl->aen_masked);
+}
+
 u32 nvmet_get_log_page_len(struct nvme_command *cmd)
 {
 	u32 len = le16_to_cpu(cmd->get_log_page.numdu);
@@ -176,7 +189,7 @@ static void nvmet_execute_get_log_changed_ns(struct nvmet_req *req)
 	if (!status)
 		status = nvmet_zero_sgl(req, len, req->data_len - len);
 	ctrl->nr_changed_ns = 0;
-	clear_bit(NVME_AEN_CFG_NS_ATTR, &ctrl->aen_masked);
+	nvmet_clear_aen(req, NVME_AEN_CFG_NS_ATTR);
 	mutex_unlock(&ctrl->lock);
 out:
 	nvmet_req_complete(req, status);
@@ -235,7 +248,7 @@ static void nvmet_execute_get_log_page_ana(struct nvmet_req *req)
 
 	hdr.chgcnt = cpu_to_le64(nvmet_ana_chgcnt);
 	hdr.ngrps = cpu_to_le16(ngrps);
-	clear_bit(NVME_AEN_CFG_ANA_CHANGE, &req->sq->ctrl->aen_masked);
+	nvmet_clear_aen(req, NVME_AEN_CFG_ANA_CHANGE);
 	up_read(&nvmet_ana_sem);
 
 	kfree(desc);