nvmet: don't defer passthrough commands with trivial effects to the workqueue

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 execute 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")
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Keith Busch <kbusch@kernel.org>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Reviewed-by: Kanchan Joshi <joshi.k@samsung.com>

diff --git a/drivers/nvme/target/passthru.c b/drivers/nvme/target/passthru.c
index 79af514..adc0958 100644 (file)
--- 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);