[RESEND RFC PATCH v4 0/4] migrates ocfs2 DIO from buffer_head to iomap

[Heming Zhao <heming.zhao@suse.com>]

Previously, I sent a v4 patch set based on commit 4056b3c9d3c9 (v7.3),
which caused sashiko to fail to apply the patches. Therefore, I am
resending the patch set based on commit 6628e7d4c6b2 (v7.4-rc1).

---
This patch set migrates ocfs2 Direct I/O (DIO) from buffer_head mode
to iomap mode. And the code base is commit 6628e7d4c6b2, and also
merge Joseph's code and ideas from [1]:

v4 changelog:

Fix several issues found during a sashiko review[2].

To simplify iomap development, we currently adopt the simplest approach:
retaining the buffer_head style, where only one cluster is allocated
per iomap_begin() call.

When creating a filesystem using "mkfs -b 2K -C 8K" (where the cluster
size is greater than the page size), several xfstests cases crashed.
The root cause was an incorrect return value from iomap end_io.

Both the add and del of the orphan inode during write I/O are now placed
in ocfs2_file_write_iter().

Additionally, I attempted to implement .submit_io/.end_io in "struct
iomap_dio_ops" to free dwc inside end_io. However, because ->bi_end_io
runs in an interrupt context and ocfs2_iomap_dio_end_io_write() contains
sleepable functions, this approach required scheduling a workqueue directly
from the ->bi_end_io callback and calling ocfs2_iomap_dio_end_io_write()
within the workqueue thread context. Furthermore, since iomap_dio_ops.end_io
still cannot access any private data, it cannot accurately wait for the
work to finish. Testing with xfstests triggered hangs and crashes.


[1]:
https://gitee.com/anolis/storage-cloud-kernel/commit/ea3fe75e2060118ba093e90b1cd34fa382914b29

[2]:
https://sashiko.dev/#/patchset/20261018143319.22329-1-heming.zhao%40suse.com

v1 patch set:
https://lore.kernel.org/ocfs2-devel/20260724052559.15409-1-heming.zhao@suse.com/
v2 patch set:
https://lore.kernel.org/ocfs2-devel/20260727061802.18485-1-heming.zhao@suse.com/
v3 patch set:
https://lore.kernel.org/ocfs2-devel/20261018143319.22329-1-heming.zhao@suse.com/

--------------
# test report

This patch set has been tested on 7.3.0-rc7 kernel with the following test
cases.

## ltp

runltp -f dio -d /mnt/ocfs2/

1 fail: diotest4    9  TCONF  :  diotest4.c:346: Direct I/O on /dev/null is not supported

This fail can be ignored.

The test results: passed

## xfstests

./check -g quick -T -b -s ocfs2 -e generic/081 \
-e generic/266 -e generic/272 -e generic/281 \
-e generic/338 -e generic/347 -e generic/361 \
-e generic/628 -e generic/629 -e generic/648 -e generic/650 

The test results are the same before and after the patch set.

```
OCFS2_MKFS_LOCAL_OPT="-b 2K -C 4K --fs-features=local --fs-feature-level=max-features"
Failures: generic/003 generic/091 generic/094 generic/177 generic/211
generic/225 generic/263 generic/322 generic/329 generic/331 generic/370
generic/376 generic/424 generic/448 generic/467 generic/477 generic/481
generic/510 generic/513 generic/537 generic/552 generic/563 generic/578
generic/607 generic/620 generic/630 generic/755 generic/760 generic/777
generic/784
Failed 30 of 632 tests

OCFS2_MKFS_LOCAL_OPT="-b 4K -C 4K --fs-features=local --fs-feature-level=max-features"
Failures: generic/003 generic/177 generic/211 generic/322 generic/329
generic/331 generic/370 generic/376 generic/420 generic/424 generic/448
generic/467 generic/477 generic/481 generic/510 generic/513 generic/537
generic/552 generic/563 generic/578 generic/607 generic/620 generic/630
generic/755 generic/777 generic/784
Failed 26 of 632 tests

OCFS2_MKFS_LOCAL_OPT="-b 2K -C 8K --fs-features=local --fs-feature-level=max-features"
Failures: generic/003 generic/075 generic/091 generic/094 generic/112
generic/177 generic/211 generic/225 generic/263 generic/322 generic/329
generic/331 generic/370 generic/376 generic/424 generic/448 generic/467
generic/477 generic/481 generic/510 generic/513 generic/537 generic/552
generic/563 generic/564 generic/578 generic/607 generic/620 generic/630
generic/755 generic/759 generic/760 generic/777 generic/784 ocfs2/001
Failed 35 of 632 tests

OCFS2_MKFS_CLUSTER_OPT="-b 2K -C 4K -N 2 --fs-feature-level=max-features --cluster-stack pcmk --cluster-name hacluster"
Failures: generic/001 generic/003 generic/091 generic/094 generic/211
generic/225 generic/263 generic/322 generic/329 generic/331 generic/370
generic/376 generic/424 generic/448 generic/467 generic/477 generic/510
generic/513 generic/537 generic/552 generic/563 generic/578 generic/607
generic/620 generic/630 generic/755 generic/760 generic/777 generic/784
Failed 29 of 632 tests

OCFS2_MKFS_CLUSTER_OPT="-b 4K -C 4K -N 2 --fs-feature-level=max-features --cluster-stack pcmk --cluster-name hacluster"
Failures: generic/003 generic/211 generic/322 generic/329 generic/331
generic/370 generic/376 generic/420 generic/424 generic/448 generic/467
generic/477 generic/510 generic/513 generic/537 generic/552 generic/563
generic/578 generic/607 generic/620 generic/630 generic/755 generic/777
generic/784
Failed 24 of 632 tests

OCFS2_MKFS_CLUSTER_OPT="-b 2K -C 8K -N 2 --fs-feature-level=max-features --cluster-stack pcmk --cluster-name hacluster"
Failures: generic/003 generic/075 generic/091 generic/094 generic/112
generic/211 generic/225 generic/263 generic/322 generic/329 generic/331
generic/370 generic/376 generic/424 generic/448 generic/467 generic/477
generic/510 generic/513 generic/537 generic/547 generic/552 generic/563
generic/564 generic/578 generic/607 generic/620 generic/630 generic/755
generic/759 generic/760 generic/777 generic/784
Failed 33 of 632 tests
```

## fio on single node

fio --direct=1 --iodepth=32 --rw=write --ioengine=libaio --bs=128k --size=1g \
--numjobs=4 --runtime=100 --group_reporting --filename=/mnt/ocfs2/write.1g --name=tst
- before patch write: IOPS=31.5k, BW=3935MiB/s (4126MB/s)(4096MiB/1041msec)
- before path overwrite (don't remove write.1g, run above fio command):
      write: IOPS=39.5k, BW=4935MiB/s (5175MB/s)(4096MiB/830msec)
- applied patch write: IOPS=37.4k, BW=4676MiB/s (4903MB/s)(4096MiB/876msec)
- applied patch overwrite (don't remove write.1g, run above fio command):
      write: IOPS=39.4k, BW=4929MiB/s (5168MB/s)(4096MiB/831msec)

fio --direct=1 --iodepth=32 --rw=read --ioengine=libaio --bs=128k --size=1g \
--numjobs=4 --runtime=100 --group_reporting --filename=/mnt/ocfs2/write.1g --name=tst
- before patch : IOPS=47.7k, BW=5962MiB/s (6252MB/s)(4096MiB/687msec)
- applied patch: IOPS=48.2k, BW=6024MiB/s (6316MB/s)(4096MiB/680msec)

fio --direct=1 --iodepth=32 --rw=randwrite --ioengine=libaio --bs=4k --size=1g \
--numjobs=4 --runtime=100 --group_reporting --filename=/mnt/ocfs2/write.1g --name=tst
- before patch
  - creating write      : IOPS=3282, BW=12.8MiB/s (13.4MB/s)(1283MiB/100026msec)
  - overwriting write.1g: IOPS=41.8k, BW=163MiB/s (171MB/s)(4096MiB/25115msec)
- applied patch
  - creating write      : IOPS=3230, BW=12.6MiB/s (13.2MB/s)(1262MiB/100031msec)
  - overwriting write.1g: IOPS=40.5k, BW=158MiB/s (166MB/s)(4096MiB/25908msec)

fio --direct=1 --iodepth=32 --rw=randread --ioengine=libaio --bs=4k --size=1g \
--numjobs=4 --runtime=100 --group_reporting --filename=/mnt/ocfs2/write.1g --name=tst
- before patch  read: IOPS=361k, BW=1409MiB/s (1477MB/s)(4096MiB/2907msec)
- applied patch read: IOPS=362k, BW=1416MiB/s (1485MB/s)(4096MiB/2893msec)

---------------------

Heming Zhao (4):
  ocfs2: Add new ocfs2_map_blocks() to introduce iomap feature
  ocfs2: switch DIO read path from buffer_head to iomap
  ocfs2: switch dio write path from buffer_head to iomap
  ocfs2: remove legacy blockdev direct-IO path APIs

 fs/ocfs2/Kconfig          |   2 +-
 fs/ocfs2/aops.c           | 568 +++++++++++++++++++++++++-------------
 fs/ocfs2/aops.h           |  38 +--
 fs/ocfs2/buffer_head_io.c |  12 -
 fs/ocfs2/file.c           | 213 ++++++++++++--
 fs/ocfs2/ocfs2.h          |  46 ++-
 fs/ocfs2/ocfs2_fs.h       |   3 +
 7 files changed, 616 insertions(+), 266 deletions(-)

-- 
2.55.0