@@ -92,6 +92,10 @@ static bool debug_large_lbas;
module_param(debug_large_lbas, bool, 0644);
MODULE_PARM_DESC(debug_large_lbas, "allow LBAs > PAGE_SIZE");
+static unsigned int debug_large_atomics;
+module_param(debug_large_atomics, uint, 0644);
+MODULE_PARM_DESC(debug_large_atomics, "allow large atomics <= awun or nawun <= mdts");
+
/*
* nvme_wq - hosts nvme related works that are not reset or delete
* nvme_reset_wq - hosts nvme reset works
@@ -1958,6 +1962,20 @@ static void nvme_update_disk_info(struct gendisk *disk,
* be aware of out of order reads/writes as npwg and nows
* are purely performance optimizations.
*/
+
+ /*
+ * If you're not concerned about power failure, in theory,
+ * you should be able to experiment up to awun rather safely.
+ *
+ * Ignore qemu awun value of 1.
+ */
+ if (debug_large_atomics && awun != 1) {
+ debug_large_atomics = min(awun_bs, debug_large_atomics);
+ phys_bs = atomic_bs = debug_large_atomics;
+ dev_info(ns->ctrl->device,
+ "Forcing large atomic: %u (awun_bs: %u awun: %u)\n",
+ debug_large_atomics, awun_bs, awun);
+ }
}
blk_queue_logical_block_size(disk->queue, bs);
A drive with atomic write support should have awun / nawun defined, for these drives it should be possible to play with and experiment safely with LBS support up to awun / nawun settings if you are completely ignoring power failure situations. Add support to experiment with this. The rationale to limit to awun / nawun is to avoid races with other on flight commands which otherwise could cause unexpected results. This also means this debug module parameter feature is not supported if your drive does not support atomics / awun / nawun. Suggested-by: Dan Helmick <dan.helmick@samsung.com> Signed-off-by: Luis Chamberlain <mcgrof@kernel.org> --- drivers/nvme/host/core.c | 18 ++++++++++++++++++ 1 file changed, 18 insertions(+)