[PATCH v2 0/2] NVMe Atomic Write fixes

[Alan Adamson]

v2: 1/2 - Change wording of patch subject and description

    2/2 - Rather than setting a controllers atomic write size to 512b if it doesn't
          match the subsystem atomic write size, if a controllers atomic write size
          is greater than he subsystem atomic write size, reject to probe.


This patch set includes 2 fixes for NVMe Atomic Writes that are reproducable
when CMIC.MCTRS (multi-controller support) is set:

    PATCH 1/2 - nvme: multipath: enable BLK_FEAT_ATOMIC_WRITES for multipathing
    PATCH 2/2 - nvme: all namespaces in a subsystem must adhere to a common atomic write size

QEMU v10.0 can be used to reproduce and validate the fixes.


nvme: multipath: enable BLK_FEAT_ATOMIC_WRITES for multipathing
--------------------------------------------------------------------------
- Include BLK_FEAT_ATOMIC_WRITES feature when allocating multipath disk (nvme_mpath_alloc_disk).


QEMU Config
===========
-device nvme,id=nvme-ctrl-0,serial=nvme-1,atomic.dn=off,atomic.awun=31,atomic.awupf=15 \
    -drive file=/dev/nullb2,if=none,id=nvm-1 \
    -device nvme-ns,drive=nvm-1,bus=nvme-ctrl-0,nsid=1 \
-device nvme,id=nvme-ctrl-1,serial=nvme-2,atomic.dn=off,atomic.awun=31,atomic.awupf=7 \
    -drive file=/dev/nullb3,if=none,id=nvm-2 \
    -device nvme-ns,drive=nvm-2,bus=nvme-ctrl-1,nsid=2 \
-device nvme,id=nvme-ctrl-2,serial=nvme-3,atomic.dn=off,atomic.awun=127,atomic.awupf=63 \
    -drive file=/dev/nullb4,if=none,id=nvm-3 \
    -device nvme-ns,drive=nvm-3,bus=nvme-ctrl-2 \


Before
======
[root at localhost ~]# nvme id-ctrl /dev/nvme1n1 | grep cmic
cmic      : 0x2
[root at localhost ~]# nvme id-ctrl /dev/nvme1n1 | grep awupf
awupf     : 63
[root at localhost ~]# nvme id-ns /dev/nvme1n1 | grep nawupf
nawupf  : 0
[root at localhost ~]# cat /sys/block/nvme1n1/queue/atomic_write_max_bytes
0
[root at localhost ~]# 

AFTER
=====
[root at localhost ~]# nvme id-ctrl /dev/nvme1n1 | grep cmic
cmic      : 0x2
[root at localhost ~]# nvme id-ctrl /dev/nvme1n1 | grep awupf
awupf     : 63
[root at localhost ~]# nvme id-ns /dev/nvme1n1 | grep nawupf
nawupf  : 0
[root at localhost ~]#  cat /sys/block/nvme1n1/queue/atomic_write_max_bytes
32768
[root at localhost ~]# 






nvme: all namespaces in a subsystem must adhere to a common atomic write size
------------------------------------------------------------------------------
- Replace awupf field in nvme_subsystem struct with atomic_bs.  The atomic_bs 
value with awupf or nawupf. (nvme_update_disk_info)
- When a namespace is added, the atomic write size (from awupf or nawupf) is
checked with subsys->atomic_bs.  If they don't match, the atomic write size is
set to 512 (1U << head->lba_shift) and a message in logged. (nvme_update_disk_info)


QEMU Config
===========
-device nvme-subsys,id=subsys0 \
    -device nvme,serial=deadbeef,id=nvme0,subsys=subsys0,atomic.dn=off,atomic.awun=31,atomic.awupf=15 \
        -drive id=ns1,file=/dev/nullb1,if=none \
        -device nvme-ns,drive=ns1,bus=nvme0,nsid=1,zoned=false,shared=false \
    -device nvme,serial=deadbeef,id=nvme1,subsys=subsys0,atomic.dn=off,atomic.awun=63,atomic.awupf=31 \
        -drive id=ns2,file=/dev/nullb2,if=none \
        -device nvme-ns,drive=ns2,bus=nvme1,nsid=2,zoned=false,shared=false \


BEFORE
======
[root at localhost ~]# nvme id-ctrl /dev/nvme0n1 | grep cmic
cmic      : 0x2
[root at localhost ~]#  nvme id-ctrl /dev/nvme0n1 | grep awupf
awupf     : 15
[root at localhost ~]# nvme id-ns /dev/nvme0n1 | grep nawupf
nawupf  : 0
[root at localhost ~]# cat /sys/block/nvme0n1/queue/atomic_write_max_bytes
8192
[root at localhost ~]# nvme id-ctrl /dev/nvme0n2 | grep cmic
cmic      : 0x2
[root at localhost ~]# nvme id-ctrl /dev/nvme0n2 | grep awupf
awupf     : 31
[root at localhost ~]# nvme id-ns /dev/nvme0n2 | grep nawupf
nawupf  : 0
[root at localhost ~]# cat /sys/block/nvme0n2/queue/atomic_write_max_bytes
8192
[root at localhost ~]# 

AFTER
=====
[root at localhost ~]# lsblk
NAME        MAJ:MIN RM  SIZE RO TYPE MOUNTPOINTS
sda           8:0    0   40G  0 disk 
├─sda1        8:1    0    1G  0 part /boot
└─sda2        8:2    0   39G  0 part 
  └─ol-root 252:0    0   39G  0 lvm  /
sr0          11:0    1 1024M  0 rom  
nvme1n2     259:1    0  250G  0 disk 
[root at localhost ~]# sh testxx.sh nvme1n2
+ nvme id-ctrl /dev/nvme1n2
+ grep cmic
cmic      : 0x2
+ nvme id-ctrl /dev/nvme1n2
+ grep awupf
awupf     : 15
+ nvme id-ns /dev/nvme1n2
+ grep nawupf
nawupf  : 0
+ cat /sys/block/nvme1n2/queue/atomic_write_max_bytes
8192

Console output:
[    2.849583] nvme1c0n1: Inconsistent Atomic Write Size: Subsystem=8192 bytes, Controller/Namespace=16384 bytes

-- 
2.43.5