From: "Darrick J. Wong" <djwong@kernel.org>
To: djwong@kernel.org
Cc: linux-xfs@vger.kernel.org, mcgrof@kernel.org,
ruansy.fnst@fujitsu.com, linux-fsdevel@vger.kernel.org
Subject: [PATCHSET RFC v24.6 0/4] xfs: online repair for fs summary counters with exclusive fsfreeze
Date: Tue, 02 May 2023 20:02:13 -0700 [thread overview]
Message-ID: <168308293319.734377.10454919162350827812.stgit@frogsfrogsfrogs> (raw)
Hi all,
A longstanding deficiency in the online fs summary counter scrubbing
code is that it hasn't any means to quiesce the incore percpu counters
while it's running. There is no way to coordinate with other threads
are reserving or freeing free space simultaneously, which leads to false
error reports. Right now, if the discrepancy is large, we just sort of
shrug and bail out with an incomplete flag, but this is lame.
For repair activity, we actually /do/ need to stabilize the counters to
get an accurate reading and install it in the percpu counter. To
improve the former and enable the latter, allow the fscounters online
fsck code to perform an exclusive mini-freeze on the filesystem. The
exclusivity prevents userspace from thawing while we're running, and the
mini-freeze means that we don't wait for the log to quiesce, which will
make both speedier.
If you're going to start using this mess, you probably ought to just
pull from my git trees, which are linked below.
This is an extraordinary way to destroy everything. Enjoy!
Comments and questions are, as always, welcome.
--D
kernel git tree:
https://git.kernel.org/cgit/linux/kernel/git/djwong/xfs-linux.git/log/?h=repair-fscounters
fstests git tree:
https://git.kernel.org/cgit/linux/kernel/git/djwong/xfstests-dev.git/log/?h=repair-fscounters
---
fs/super.c | 74 ++++++++++++++-
fs/xfs/Makefile | 1
fs/xfs/scrub/fscounters.c | 185 ++++++++++++++++++++++++++++----------
fs/xfs/scrub/fscounters.h | 20 ++++
fs/xfs/scrub/fscounters_repair.c | 72 +++++++++++++++
fs/xfs/scrub/repair.h | 2
fs/xfs/scrub/scrub.c | 8 +-
fs/xfs/scrub/scrub.h | 1
fs/xfs/scrub/trace.c | 1
fs/xfs/scrub/trace.h | 22 ++++-
fs/xfs/xfs_super.c | 20 ++++
fs/xfs/xfs_super.h | 2
include/linux/fs.h | 3 +
13 files changed, 348 insertions(+), 63 deletions(-)
create mode 100644 fs/xfs/scrub/fscounters.h
create mode 100644 fs/xfs/scrub/fscounters_repair.c
next reply other threads:[~2023-05-03 3:02 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-05-03 3:02 Darrick J. Wong [this message]
2023-05-03 3:02 ` [PATCH 1/4] vfs: allow filesystem freeze callers to denote who froze the fs Darrick J. Wong
2023-05-07 5:23 ` Luis Chamberlain
2023-05-17 17:13 ` Shiyang Ruan
2023-05-18 6:07 ` Darrick J. Wong
2023-05-03 3:02 ` [PATCH 2/4] vfs: allow exclusive freezing of filesystems Darrick J. Wong
2023-05-03 3:02 ` [PATCH 3/4] xfs: stabilize fs summary counters for online fsck Darrick J. Wong
2023-05-03 3:02 ` [PATCH 4/4] xfs: repair summary counters Darrick J. Wong
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