[PATCH v2 0/6] iomap: some minor non-critical fixes and improvements when block size < folio size

Zhang Yi
2024-08-12T12:16:20Z

From: Zhang Yi <yi.zhang@huawei.com>

Changes since v1:
- Patch 5 fix a stale data exposure problem pointed out by Willy, drop
the setting of uptodate bits after zeroing out unaligned range.
- As Dave suggested, in order to prevent increasing the complexity of
maintain the state_lock, don't just drop all the state_lock in the
buffered write path, patch 6 introduce a new helper to set uptodate
bit and dirty bits together under the state_lock, reduce one time of
locking per write, the benefits of performance optimization do not
change too much.

This series contains some minor non-critical fixes and performance
improvements on the filesystem with block size < folio size.

The first 4 patches fix the handling of setting and clearing folio ifs
dirty bits when mark the folio dirty and when invalidat the folio.
Although none of these code mistakes caused a real problem now, it's
still deserve a fix to correct the behavior.

The second 2 patches drop the unnecessary state_lock in ifs when setting
and clearing dirty/uptodate bits in the buffered write path, it could
improve some (~8% on my machine) buffer write performance. I tested it
through UnixBench on my x86_64 (Xeon Gold 6151) and arm64 (Kunpeng-920)
virtual machine with 50GB ramdisk and xfs filesystem, the results shows
below.

UnixBench test cmd:
./Run -i 1 -c 1 fstime-w

Before:
x86 File Write 1024 bufsize 2000 maxblocks 524708.0 KBps
arm64 File Write 1024 bufsize 2000 maxblocks 801965.0 KBps

After:
x86 File Write 1024 bufsize 2000 maxblocks 569218.0 KBps
arm64 File Write 1024 bufsize 2000 maxblocks 871605.0 KBps

Thanks,
Yi.

Zhang Yi (6):
iomap: correct the range of a partial dirty clear
iomap: support invalidating partial folios
iomap: advance the ifs allocation if we have more than one blocks per
folio
iomap: correct the dirty length in page mkwrite
iomap: don't mark blocks uptodate after partial zeroing
iomap: reduce unnecessary state_lock when setting ifs uptodate and
dirty bits

fs/iomap/buffered-io.c | 73 ++++++++++++++++++++++++++++++++++--------
1 file changed, 60 insertions(+), 13 deletions(-)

--
2.39.2