[PATCH v4 11/11] nvme: Ensure atomic writes will be executed atomically

[John Garry <john.g.garry@oracle.com>]

From: Alan Adamson <alan.adamson@oracle.com>

There is no dedicated NVMe atomic write command (which may error for a
command which exceeds the controller atomic write limits).

As an insurance policy against the block layer sending requests which
cannot be executed atomically, add a check in the queue path.

Signed-off-by: Alan Adamson <alan.adamson@oracle.com>
#jpg: some rewrite
Signed-off-by: John Garry <john.g.garry@oracle.com>
---
 drivers/nvme/host/core.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index c5bc663c8582..60dc20864dc7 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -934,7 +934,6 @@ static inline blk_status_t nvme_setup_write_zeroes(struct nvme_ns *ns,
 	return BLK_STS_OK;
 }
 
-__maybe_unused
 static bool nvme_valid_atomic_write(struct request *req)
 {
 	struct request_queue *q = req->q;
@@ -974,6 +973,13 @@ static inline blk_status_t nvme_setup_rw(struct nvme_ns *ns,
 	if (req->cmd_flags & REQ_RAHEAD)
 		dsmgmt |= NVME_RW_DSM_FREQ_PREFETCH;
 
+	/*
+	 * Ensure that nothing has been sent which cannot be executed
+	 * atomically.
+	 */
+	if (req->cmd_flags & REQ_ATOMIC && !nvme_valid_atomic_write(req))
+		return BLK_STS_IOERR;
+
 	cmnd->rw.opcode = op;
 	cmnd->rw.flags = 0;
 	cmnd->rw.nsid = cpu_to_le32(ns->head->ns_id);
-- 
2.31.1