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 0000000 a a a a a a a a a a a a a a a a 0000016 0000512 a a a a a a a a a a a a a a a a 0000528 0001024 a a a a a a a a a a a a a a a a 0001040 0001536 a a a a a a a a a a a a a a a a 0001552 0002048 a a a a a a a a a a a a a a a a 0002064 0002560 a a a a a a a a a a a a a a a a 0002576 0003072 a a a a a a a a a a a a a a a a 0003088 0003584 a a a a a a a a a a a a a a a a 0003600 0004096 a a a a a a a a a a a a a a a a 0004112 0004608 a a a a a a a a a a a a a a a a 0004624 ------------------------------------------------------ 0000000 a a a a a a a a a a a a a a a a 0000016 0000512 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 0000528 0001024 a a a a a a a a a a a a a a a a 0001040 0001536 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 0001552 0002048 a a a a a a a a a a a a a a a a 0002064 0002560 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 0002576 0003072 a a a a a a a a a a a a a a a a 0003088 0003584 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 0003600 0004096 a a a a a a a a a a a a a a a a 0004112 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 0000016 0000512 a a a a a a a a a a a a a a a a 0000528 0001024 a a a a a a a a a a a a a a a a 0001040 0001536 a a a a a a a a a a a a a a a a 0001552 0002048 a a a a a a a a a a a a a a a a 0002064 0002560 a a a a a a a a a a a a a a a a 0002576 0003072 a a a a a a a a a a a a a a a a 0003088 0003584 a a a a a a a a a a a a a a a a 0003600 0004096 a a a a a a a a a a a a a a a a 0004112 0004608 a a a a a a a a a a a a a a a a 0004624 ------------------------------------------------------ 0000000 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 0000016 0000512 a a a a a a a a a a a a a a a a 0000528 0001024 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 0001040 0001536 a a a a a a a a a a a a a a a a 0001552 0002048 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 0002064 0002560 a a a a a a a a a a a a a a a a 0002576 0003072 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 0003088 0003584 a a a a a a a a a a a a a a a a 0003600 0004096 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 0004112 0004608 a a a a a a a a a a a a a a a a 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 0001024 a a a a a a a a a a a a a a a a 0001040 0002048 a a a a a a a a a a a a a a a a 0002064 0003072 a a a a a a a a a a a a a a a a 0003088 0004096 a a a a a a a a a a a a a a a a 0004112 0005120 a a a a a a a a a a a a a a a a 0005136 0006144 a a a a a a a a a a a a a a a a 0006160 0007168 a a a a a a a a a a a a a a a a 0007184 0008192 a a a a a a a a a a a a a a a a 0008208 0009216 a a a a a a a a a a a a a a a a 0009232 ------------------------------------------------------ 0000000 a a a a a a a a a a a a a a a a 0000016 0001024 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 0001040 0002048 a a a a a a a a a a a a a a a a 0002064 0003072 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 0003088 0004096 a a a a a a a a a a a a a a a a 0004112 0005120 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 0005136 0006144 a a a a a a a a a a a a a a a a 0006160 0007168 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 0007184 0008192 a a a a a a a a a a a a a a a a 0008208 0009216 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 0009232 ------------------------------------------------------ EVEN:- 9+1 records in 9+1 records out 10002 bytes (10 kB, 9.8 KiB) copied, 0.000325488 s, 30.7 MB/s 0000000 a a a a a a a a a a a a a a a a 0000016 0001024 a a a a a a a a a a a a a a a a 0001040 0002048 a a a a a a a a a a a a a a a a 0002064 0003072 a a a a a a a a a a a a a a a a 0003088 0004096 a a a a a a a a a a a a a a a a 0004112 0005120 a a a a a a a a a a a a a a a a 0005136 0006144 a a a a a a a a a a a a a a a a 0006160 0007168 a a a a a a a a a a a a a a a a 0007184 0008192 a a a a a a a a a a a a a a a a 0008208 0009216 a a a a a a a a a a a a a a a a 0009232 ------------------------------------------------------ 0000000 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 0000016 0001024 a a a a a a a a a a a a a a a a 0001040 0002048 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 0002064 0003072 a a a a a a a a a a a a a a a a 0003088 0004096 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 0004112 0005120 a a a a a a a a a a a a a a a a 0005136 0006144 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 0006160 0007168 a a a a a a a a a a a a a a a a 0007184 0008192 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 0008208 0009216 a a a a a a a a a a a a a a a a 0009232 ------------------------------------------------------ #################### 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 0000016 0002048 a a a a a a a a a a a a a a a a 0002064 0004096 a a a a a a a a a a a a a a a a 0004112 0006144 a a a a a a a a a a a a a a a a 0006160 0008192 a a a a a a a a a a a a a a a a 0008208 0010240 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 0010256 0012288 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 0012304 0014336 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 0014352 0016384 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 0016400 0018432 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 0018448 ------------------------------------------------------ 0000000 a a a a a a a a a a a a a a a a 0000016 0002048 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 0002064 0004096 a a a a a a a a a a a a a a a a 0004112 0006144 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 0006160 0008192 a a a a a a a a a a a a a a a a 0008208 0010240 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 0010256 0012288 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 0012304 0014336 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 0014352 0016384 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 0016400 0018432 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 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 0000000 a a a a a a a a a a a a a a a a 0000016 0002048 a a a a a a a a a a a a a a a a 0002064 0004096 a a a a a a a a a a a a a a a a 0004112 0006144 a a a a a a a a a a a a a a a a 0006160 0008192 a a a a a a a a a a a a a a a a 0008208 0010240 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 0010256 0012288 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 0012304 0014336 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 0014352 0016384 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 0016400 0018432 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 0018448 ------------------------------------------------------ 0000000 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 0000016 0002048 a a a a a a a a a a a a a a a a 0002064 0004096 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 0004112 0006144 a a a a a a a a a a a a a a a a 0006160 0008192 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 0008208 0010240 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 0010256 0012288 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 0012304 0014336 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 0014352 0016384 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 0016400 0018432 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 0018448 ------------------------------------------------------ #################### 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 ODD:- 2+1 records in 2+1 records out 10002 bytes (10 kB, 9.8 KiB) copied, 0.00028502 s, 35.1 MB/s 0000000 a a a a a a a a a a a a a a a a 0000016 0004096 a a a a a a a a a a a a a a a a 0004112 0008192 a a a a a a a a a a a a a a a a 0008208 0012288 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 0012304 0016384 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 0016400 0020480 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 0020496 0024576 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 0024592 0028672 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 0028688 0032768 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 0032784 0036864 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 0036880 ------------------------------------------------------ 0000000 a a a a a a a a a a a a a a a a 0000016 0004096 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 0004112 0008192 a a a a a a a a a a a a a a a a 0008208 0012288 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 0012304 0016384 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 0016400 0020480 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 0020496 0024576 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 0024592 0028672 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 0028688 0032768 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 0032784 0036864 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 0036880 ------------------------------------------------------ EVEN:- 2+1 records in 2+1 records out 10002 bytes (10 kB, 9.8 KiB) copied, 0.00024765 s, 40.4 MB/s 0000000 a a a a a a a a a a a a a a a a 0000016 0004096 a a a a a a a a a a a a a a a a 0004112 0008192 a a a a a a a a a a a a a a a a 0008208 0012288 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 0012304 0016384 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 0016400 0020480 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 0020496 0024576 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 0024592 0028672 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 0028688 0032768 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 0032784 0036864 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 0036880 ------------------------------------------------------ 0000000 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 0000016 0004096 a a a a a a a a a a a a a a a a 0004112 0008192 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 0008208 0012288 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 0012304 0016384 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 0016400 0020480 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 0020496 0024576 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 0024592 0028672 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 0028688 0032768 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 0032784 0036864 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 0036880 ------------------------------------------------------
