[PATCH 4/6] nvmet: don't defer passthrough commands with trivial effects to the workqueue

[Christoph Hellwig]

Mask out the "Command Supported" and "Logical Block Content Change" bits
and only defer execution of commands that have non-trivial effects to
the workqueue for synchronous execution.  This allows to execture admin
commands asynchronously on controllers that provide a Command Supported
and Effects log page, and will keep allowing to execute Write commands
asynchronously once command effects on I/O commands are taken into
account.

Fixes: c1fef73f793b ("nvmet: add passthru code to process commands")
Reviewed-by: Kanchan Joshi <joshi.k at samsung.com>
Signed-off-by: Christoph Hellwig <hch at lst.de>
---
 drivers/nvme/target/passthru.c | 11 +++++------
 1 file changed, 5 insertions(+), 6 deletions(-)

diff --git a/drivers/nvme/target/passthru.c b/drivers/nvme/target/passthru.c
index 79af5140af8bfe..adc0958755d66f 100644
--- a/drivers/nvme/target/passthru.c
+++ b/drivers/nvme/target/passthru.c
@@ -334,14 +334,13 @@ static void nvmet_passthru_execute_cmd(struct nvmet_req *req)
 	}
 
 	/*
-	 * If there are effects for the command we are about to execute, or
-	 * an end_req function we need to use nvme_execute_passthru_rq()
-	 * synchronously in a work item seeing the end_req function and
-	 * nvme_passthru_end() can't be called in the request done callback
-	 * which is typically in interrupt context.
+	 * If a command needs post-execution fixups, or there are any
+	 * non-trivial effects, make sure to execute the command synchronously
+	 * in a workqueue so that nvme_passthru_end gets called.
 	 */
 	effects = nvme_command_effects(ctrl, ns, req->cmd->common.opcode);
-	if (req->p.use_workqueue || effects) {
+	if (req->p.use_workqueue ||
+	    (effects & ~(NVME_CMD_EFFECTS_CSUPP | NVME_CMD_EFFECTS_LBCC))) {
 		INIT_WORK(&req->p.work, nvmet_passthru_execute_cmd_work);
 		req->p.rq = rq;
 		queue_work(nvmet_wq, &req->p.work);
-- 
2.35.1