[PATCHv11 0/8] iomap: Add support for per-block dirty state to improve write performance

["Ritesh Harjani (IBM)" <ritesh.list@gmail.com>]

Hello All,

Please find PATCHv11 which adds per-block dirty tracking to iomap.
As discussed earlier this is required to improve write performance and reduce
write amplification for cases where either blocksize is less than pagesize (such
as Power platform with 64k pagesize) or when we have a large folio (such as xfs
which currently supports large folio).

Thanks everyone for helping with reviews and suggestions.

v10 -> v11:
===========
1. Dropped iomap_block_state enum. Thereby automatically addressing variables
   names like first_blk etc. in bitmap handling functions.

Testing of v11:
===============
1. I have done fstests testing of v11 on my setup for x86 (1k & 4k bs),
   arm (4k bs) and Power (4k bs) with xfstests. I haven't found any new
   failures as such in my testing so far with xfstests.
2. I have also done some random read/write testing using fio & haven't
   observed any performance issues in my testing so far.

<Perf data copy paste from previous version>
=============================================
Performance testing of below fio workload reveals ~16x performance
improvement using nvme with XFS (4k blocksize) on Power (64K pagesize)
FIO reported write bw scores improved from around ~28 MBps to ~452 MBps.

1. <test_randwrite.fio>
[global]
	ioengine=psync
	rw=randwrite
	overwrite=1
	pre_read=1
	direct=0
	bs=4k
	size=1G
	dir=./
	numjobs=8
	fdatasync=1
	runtime=60
	iodepth=64
	group_reporting=1

[fio-run]

2. Also our internal performance team reported that this patch improves
   their database workload performance by around ~83% (with XFS on Power)

Ritesh Harjani (IBM) (8):
  iomap: Rename iomap_page to iomap_folio_state and others
  iomap: Drop ifs argument from iomap_set_range_uptodate()
  iomap: Add some uptodate state handling helpers for ifs state bitmap
  iomap: Fix possible overflow condition in iomap_write_delalloc_scan
  iomap: Use iomap_punch_t typedef
  iomap: Refactor iomap_write_delalloc_punch() function out
  iomap: Allocate ifs in ->write_begin() early
  iomap: Add per-block dirty state tracking to improve performance

 fs/gfs2/aops.c         |   2 +-
 fs/iomap/buffered-io.c | 402 ++++++++++++++++++++++++++++-------------
 fs/xfs/xfs_aops.c      |   2 +-
 fs/zonefs/file.c       |   2 +-
 include/linux/iomap.h  |   1 +
 5 files changed, 281 insertions(+), 128 deletions(-)

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2.40.1