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From:   Chaitanya Kulkarni <kch@nvidia.com>
To:     <linux-block@vger.kernel.org>, <linux-kernel@vger.kernel.org>
CC:     <axboe@kernel.dk>, <kch@nvidia.com>,
        <damien.lemoal@opensource.wdc.com>, <johannes.thumshirn@wdc.com>,
        <bvanassche@acm.org>, <ming.lei@redhat.com>,
        <shinichiro.kawasaki@wdc.com>, <vincent.fu@samsung.com>,
        <yukuai3@huawei.com>
Subject: [PATCH 0/6] null_blk: allow REQ_OP_WRITE_ZEROES and cleanup
Date:   Tue, 4 Oct 2022 20:16:55 -0700
Message-ID: <20221005031701.79077-1-kch@nvidia.com>
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Hi,

In order to test the non-trivial I/O path in the block layer for
REQ_OP_WRITE_ZEROES allow write-zeroes on null_blk so we can write
testcases with and without non-memory backed mode followed by
few cleanup patches.

Below is the test report with ext2/ext4 mkfs and a blktest
waiting to get upstream for this patch-series.

-ck

Chaitanya Kulkarni (6):
  null_blk: allow write zeores on non-membacked
  null_blk: allow write zeores on membacked
  null_blk: code cleaup
  null_blk: initialize cmd->bio in __alloc_cmd()
  null_blk: don't use magic numbers in the code
  null_blk: remove extra space in switch condition

 drivers/block/null_blk/main.c     | 131 ++++++++++++++++++++++--------
 drivers/block/null_blk/null_blk.h |   1 +
 2 files changed, 97 insertions(+), 35 deletions(-)

1. Write Zeroes test with ext2/ext3 for memory backed :-
linux-block (for-next) # mkfs.ext2 /dev/nullb0 
mke2fs 1.45.6 (20-Mar-2020)
Creating filesystem with 262144 4k blocks and 65536 inodes
Filesystem UUID: 76037c2c-9c32-4ac6-b1d6-d1f62e6071ad
Superblock backups stored on blocks: 
	32768, 98304, 163840, 229376

Allocating group tables: done                            
Writing inode tables: done                            
Writing superblocks and filesystem accounting information: done

linux-block (for-next) # mount /dev/nullb0 /mnt/
backend/ data/    nullb0/  nvme1n1/ test/    
linux-block (for-next) # mount /dev/nullb0 /mnt/nullb0/
linux-block (for-next) # dmesg  -c 
[18833.072830] null_blk: null_handle_write_zeroes 1225 2097024 128
[18833.072963] null_blk: null_handle_write_zeroes 1225 536 4096
[18833.073439] null_blk: null_handle_write_zeroes 1225 262680 4096
[18833.073845] null_blk: null_handle_write_zeroes 1225 524304 4096
[18833.074202] null_blk: null_handle_write_zeroes 1225 786968 4096
[18833.074581] null_blk: null_handle_write_zeroes 1225 1048592 4096
[18833.074951] null_blk: null_handle_write_zeroes 1225 1311256 4096
[18833.075381] null_blk: null_handle_write_zeroes 1225 1572880 4096
[18833.075748] null_blk: null_handle_write_zeroes 1225 1835544 4096
[18833.076164] null_blk: null_handle_write_zeroes 1225 4672 8
[18844.752019] EXT4-fs (nullb0): mounting ext2 file system using the ext4 subsystem
[18844.752487] EXT4-fs (nullb0): mounted filesystem without journal. Quota mode: none.
linux-block (for-next) # 


linux-block (for-next) # mkfs.ext4 /dev/nullb0 
mke2fs 1.45.6 (20-Mar-2020)
/dev/nullb0 contains a ext2 file system
	last mounted on Mon Oct  3 18:28:05 2022
Proceed anyway? (y,N) y
Creating filesystem with 262144 4k blocks and 65536 inodes
Filesystem UUID: a4c66d5f-bda9-4f58-aa03-911b87bb5c7d
Superblock backups stored on blocks: 
	32768, 98304, 163840, 229376

Allocating group tables: done                            
Writing inode tables: done                            
Creating journal (8192 blocks): done
Writing superblocks and filesystem accounting information: done

linux-block (for-next) # mount /dev/nullb0 /mnt/nullb0/
linux-block (for-next) # dmesg  -c 
[18882.721160] EXT4-fs (nullb0): unmounting filesystem.
[18888.687070] null_blk: null_handle_write_zeroes 1225 2097024 128
[18888.687159] null_blk: null_handle_write_zeroes 1225 1160 8
[18888.687309] null_blk: null_handle_write_zeroes 1225 33968 8
[18888.687839] null_blk: null_handle_write_zeroes 1225 1048576 65536
[18892.105964] EXT4-fs (nullb0): mounted filesystem with ordered data mode. Quota mode: none.
linux-block (for-next) # 

2. Test blkdiscard with -z for different block sizes :-

linux-block (for-next) # ./zeroout.sh 
#################### BLKISZ 512 #####################
config/nullb/nullb0
├── badblocks
├── blocking
├── blocksize
├── cache_size
├── completion_nsec
├── discard
├── home_node
├── hw_queue_depth
├── index
├── irqmode
├── max_sectors
├── mbps
├── memory_backed
├── no_sched
├── poll_queues
├── power
├── queue_mode
├── shared_tag_bitmap
├── size
├── submit_queues
├── use_per_node_hctx
├── virt_boundary
├── write_zeroes
├── zone_capacity
├── zoned
├── zone_max_active
├── zone_max_open
├── zone_nr_conv
└── zone_size

0 directories, 29 files
ODD:- 
19+1 records in
19+1 records out
10002 bytes (10 kB, 9.8 KiB) copied, 0.000521991 s, 19.2 MB/s
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------------------------------------------------------
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0004608  \0  \0  \0  \0  \0  \0  \0  \0  \0  \0  \0  \0  \0  \0  \0  \0
0004624
------------------------------------------------------
EVEN:- 
19+1 records in
19+1 records out
10002 bytes (10 kB, 9.8 KiB) copied, 0.000376636 s, 26.6 MB/s
0000000   a   a   a   a   a   a   a   a   a   a   a   a   a   a   a   a
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0002560   a   a   a   a   a   a   a   a   a   a   a   a   a   a   a   a
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0003072   a   a   a   a   a   a   a   a   a   a   a   a   a   a   a   a
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0003584   a   a   a   a   a   a   a   a   a   a   a   a   a   a   a   a
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0004096   a   a   a   a   a   a   a   a   a   a   a   a   a   a   a   a
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0004624
------------------------------------------------------
0000000  \0  \0  \0  \0  \0  \0  \0  \0  \0  \0  \0  \0  \0  \0  \0  \0
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0004624
------------------------------------------------------


#################### BLKISZ 1024 #####################
config/nullb/nullb0
├── badblocks
├── blocking
├── blocksize
├── cache_size
├── completion_nsec
├── discard
├── home_node
├── hw_queue_depth
├── index
├── irqmode
├── max_sectors
├── mbps
├── memory_backed
├── no_sched
├── poll_queues
├── power
├── queue_mode
├── shared_tag_bitmap
├── size
├── submit_queues
├── use_per_node_hctx
├── virt_boundary
├── write_zeroes
├── zone_capacity
├── zoned
├── zone_max_active
├── zone_max_open
├── zone_nr_conv
└── zone_size

0 directories, 29 files
ODD:- 
9+1 records in
9+1 records out
10002 bytes (10 kB, 9.8 KiB) copied, 0.00040033 s, 25.0 MB/s
0000000   a   a   a   a   a   a   a   a   a   a   a   a   a   a   a   a
0000016
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0009232
------------------------------------------------------
0000000   a   a   a   a   a   a   a   a   a   a   a   a   a   a   a   a
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------------------------------------------------------
EVEN:- 
9+1 records in
9+1 records out
10002 bytes (10 kB, 9.8 KiB) copied, 0.000325488 s, 30.7 MB/s
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0009232
------------------------------------------------------
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------------------------------------------------------


#################### BLKISZ 2048 #####################
config/nullb/nullb0
├── badblocks
├── blocking
├── blocksize
├── cache_size
├── completion_nsec
├── discard
├── home_node
├── hw_queue_depth
├── index
├── irqmode
├── max_sectors
├── mbps
├── memory_backed
├── no_sched
├── poll_queues
├── power
├── queue_mode
├── shared_tag_bitmap
├── size
├── submit_queues
├── use_per_node_hctx
├── virt_boundary
├── write_zeroes
├── zone_capacity
├── zoned
├── zone_max_active
├── zone_max_open
├── zone_nr_conv
└── zone_size

0 directories, 29 files
ODD:- 
4+1 records in
4+1 records out
10002 bytes (10 kB, 9.8 KiB) copied, 0.000367949 s, 27.2 MB/s
0000000   a   a   a   a   a   a   a   a   a   a   a   a   a   a   a   a
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0018448
------------------------------------------------------
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0018448
------------------------------------------------------
EVEN:- 
4+1 records in
4+1 records out
10002 bytes (10 kB, 9.8 KiB) copied, 0.000310981 s, 32.2 MB/s
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#################### BLKISZ 4096 #####################
config/nullb/nullb0
├── badblocks
├── blocking
├── blocksize
├── cache_size
├── completion_nsec
├── discard
├── home_node
├── hw_queue_depth
├── index
├── irqmode
├── max_sectors
├── mbps
├── memory_backed
├── no_sched
├── poll_queues
├── power
├── queue_mode
├── shared_tag_bitmap
├── size
├── submit_queues
├── use_per_node_hctx
├── virt_boundary
├── write_zeroes
├── zone_capacity
├── zoned
├── zone_max_active
├── zone_max_open
├── zone_nr_conv
└── zone_size

0 directories, 29 files
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