[PATCH v2 15/16] nvme: Support atomic writes

John Garry
2023-12-12T11:10:08Z

From: Alan Adamson <alan.adamson@oracle.com>

Support reading atomic write registers to fill in request_queue
properties.

Use following method to calculate limits:
atomic_write_max_bytes = flp2(NAWUPF ?: AWUPF)
atomic_write_unit_min = logical_block_size
atomic_write_unit_max = flp2(NAWUPF ?: AWUPF)
atomic_write_boundary = NABSPF

Signed-off-by: Alan Adamson <alan.adamson@oracle.com>
#jpg: some rewrite
Signed-off-by: John Garry <john.g.garry@oracle.com>
---
drivers/nvme/host/core.c | 85 ++++++++++++++++++++++++++++++----------
1 file changed, 64 insertions(+), 21 deletions(-)

diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index 8ebdfd623e0f..fd4f09f9dbe8 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -1894,12 +1894,68 @@ static void nvme_set_queue_limits(struct nvme_ctrl *ctrl,
blk_queue_write_cache(q, vwc, vwc);
}

+static void nvme_update_atomic_write_disk_info(struct gendisk *disk,
+ struct nvme_ns *ns, struct nvme_id_ns *id, u32 bs, u32 phys_bs)
+{
+ unsigned int max_bytes = 0, unit_min = 0, unit_max = 0, boundary = 0;
+ u32 atomic_bs = bs;
+
+ if (id->nabo == 0) {
+ unsigned int ns_boundary;
+
+ /*
+ * Bit 1 indicates whether NAWUPF is defined for this namespace
+ * and whether it should be used instead of AWUPF. If NAWUPF ==
+ * 0 then AWUPF must be used instead.
+ */
+ if (id->nsfeat & NVME_NS_FEAT_ATOMICS && id->nawupf)
+ atomic_bs = (1 + le16_to_cpu(id->nawupf)) * bs;
+ else
+ atomic_bs = (1 + ns->ctrl->subsys->awupf) * bs;
+
+ if (le16_to_cpu(id->nabspf))
+ ns_boundary = (le16_to_cpu(id->nabspf) + 1) * bs;
+ else
+ ns_boundary = 0;
+
+ /*
+ * The boundary size just needs to be a multiple
+ * of unit_max (and not necessarily a power-of-2), so
+ * this could be relaxed in the block layer in future.
+ */
+ if (!ns_boundary || is_power_of_2(ns_boundary)) {
+ max_bytes = atomic_bs;
+ unit_min = bs >> SECTOR_SHIFT;
+ unit_max = rounddown_pow_of_two(atomic_bs) >> SECTOR_SHIFT;
+ boundary = ns_boundary;
+ } else {
+ dev_notice(ns->ctrl->device, "Unsupported atomic write boundary (%d bytes)\n",
+ ns_boundary);
+ }
+ } else {
+ dev_info(ns->ctrl->device, "Atomic writes not supported for NABO set (%d blocks)\n",
+ id->nabo);
+ }
+
+ 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,
+ rounddown_pow_of_two(atomic_bs) >> SECTOR_SHIFT);
+ blk_queue_atomic_write_boundary_bytes(disk->queue, boundary);
+
+ /*
+ * Linux filesystems assume writing a single physical block is
+ * an atomic operation. Hence limit the physical block size to the
+ * value of the Atomic Write Unit Power Fail parameter.
+ */
+ blk_queue_physical_block_size(disk->queue, min(phys_bs, atomic_bs));
+}
+
static void nvme_update_disk_info(struct gendisk *disk,
struct nvme_ns *ns, struct nvme_id_ns *id)
{
sector_t capacity = nvme_lba_to_sect(ns, le64_to_cpu(id->nsze));
- u32 bs = 1U << ns->lba_shift;
- u32 atomic_bs, phys_bs, io_opt = 0;
+ u32 bs, phys_bs, io_opt = 0;

/*
* The block layer can't support LBA sizes larger than the page size
@@ -1909,37 +1965,24 @@ static void nvme_update_disk_info(struct gendisk *disk,
if (ns->lba_shift > PAGE_SHIFT || ns->lba_shift < SECTOR_SHIFT) {
capacity = 0;
bs = (1 << 9);
+ } else {
+ bs = 1U << ns->lba_shift;
}

blk_integrity_unregister(disk);

- atomic_bs = phys_bs = bs;
- if (id->nabo == 0) {
- /*
- * Bit 1 indicates whether NAWUPF is defined for this namespace
- * and whether it should be used instead of AWUPF. If NAWUPF ==
- * 0 then AWUPF must be used instead.
- */
- if (id->nsfeat & NVME_NS_FEAT_ATOMICS && id->nawupf)
- atomic_bs = (1 + le16_to_cpu(id->nawupf)) * bs;
- else
- atomic_bs = (1 + ns->ctrl->subsys->awupf) * bs;
- }
-
if (id->nsfeat & NVME_NS_FEAT_IO_OPT) {
/* NPWG = Namespace Preferred Write Granularity */
phys_bs = bs * (1 + le16_to_cpu(id->npwg));
/* NOWS = Namespace Optimal Write Size */
io_opt = bs * (1 + le16_to_cpu(id->nows));
+ } else {
+ phys_bs = bs;
}

+ nvme_update_atomic_write_disk_info(disk, ns, id, bs, phys_bs);
+
blk_queue_logical_block_size(disk->queue, bs);
- /*
- * Linux filesystems assume writing a single physical block is
- * an atomic operation. Hence limit the physical block size to the
- * value of the Atomic Write Unit Power Fail parameter.
- */
- blk_queue_physical_block_size(disk->queue, min(phys_bs, atomic_bs));
blk_queue_io_min(disk->queue, phys_bs);
blk_queue_io_opt(disk->queue, io_opt);

--
2.35.3