nvme: fix setting the queue depth in nvme_alloc_io_tag_set

While the CAP.MQES field in NVMe is a 0s based filed with a natural one
off, we also need to account for the queue wrap condition and fix undo
the one off again in nvme_alloc_io_tag_set.  This was never properly
done by the fabrics drivers, but they don't seem to care because there
is no actual physical queue that can wrap around, but it became a
problem when converting over the PCIe driver.  Also add back the
BLK_MQ_MAX_DEPTH check that was lost in the same commit.

Fixes: 0da7feaa5913 ("nvme-pci: use the tagset alloc/free helpers")
Reported-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Tested-by: Hugh Dickins <hughd@google.com>
Link: https://lore.kernel.org/r/20221225103234.226794-2-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index e26b085..cda1361 100644 (file)
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -4897,7 +4897,7 @@ int nvme_alloc_io_tag_set(struct nvme_ctrl *ctrl, struct blk_mq_tag_set *set,
 
        memset(set, 0, sizeof(*set));
        set->ops = ops;
-       set->queue_depth = ctrl->sqsize + 1;
+       set->queue_depth = min_t(unsigned, ctrl->sqsize, BLK_MQ_MAX_DEPTH - 1);
        /*
         * Some Apple controllers requires tags to be unique across admin and
         * the (only) I/O queue, so reserve the first 32 tags of the I/O queue.