[PATCH v2 16/16] nvme: Ensure atomic writes will be executed atomically

John Garry
2023-12-12T12:16:23Z

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>
Signed-off-by: John Garry <john.g.garry@oracle.com>
---
drivers/nvme/host/core.c | 23 +++++++++++++++++++++++
drivers/nvme/host/nvme.h | 2 ++
2 files changed, 25 insertions(+)

diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index fd4f09f9dbe8..6b89ee7e9921 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -905,6 +905,26 @@ 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) {
+ if (blk_rq_bytes(req) > ns->atomic_max)
+ return BLK_STS_IOERR;
+
+ if (ns->atomic_boundary) {
+ u32 boundary = ns->atomic_boundary >> ns->lba_shift;
+ u32 imask = ~(boundary - 1);
+ u32 lba = nvme_sect_to_lba(ns, blk_rq_pos(req));
+ u32 end = lba + (blk_rq_bytes(req) >> ns->lba_shift)
+ - 1;
+
+ if ((lba & imask) != (end & imask))
+ return BLK_STS_IOERR;
+ }
+ }
+
cmnd->rw.opcode = op;
cmnd->rw.flags = 0;
cmnd->rw.nsid = cpu_to_le32(ns->head->ns_id);
@@ -1937,6 +1957,9 @@ static void nvme_update_atomic_write_disk_info(struct gendisk *disk,
id->nabo);
}

+ ns->atomic_max = atomic_bs;
+ ns->atomic_boundary = boundary;
+
blk_queue_atomic_write_max_bytes(disk->queue, atomic_bs);
blk_queue_atomic_write_unit_min_sectors(disk->queue, bs >> SECTOR_SHIFT);
blk_queue_atomic_write_unit_max_sectors(disk->queue,
diff --git a/drivers/nvme/host/nvme.h b/drivers/nvme/host/nvme.h
index e7411dac00f7..5a3d76bc816f 100644
--- a/drivers/nvme/host/nvme.h
+++ b/drivers/nvme/host/nvme.h
@@ -520,6 +520,8 @@ struct nvme_ns {

struct nvme_fault_inject fault_inject;

+ u32 atomic_max;
+ u32 atomic_boundary;
};

/* NVMe ns supports metadata actions by the controller (generate/strip) */
--
2.35.3