linux-ext4 - [PATCHSET 1/9] fuse2fs: fix locking problems

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Message-ID: <176246793314.2862036.15869840216751367735.stgit@frogsfrogsfrogs>
Date: Thu, 06 Nov 2025 14:27:52 -0800
From: "Darrick J. Wong" <djwong@...nel.org>
To: tytso@....edu
Cc: linux-ext4@...r.kernel.org, linux-ext4@...r.kernel.org
Subject: [PATCHSET 1/9] fuse2fs: fix locking problems

Hi all,

Teach fuse2fs to flock the file(s) underlying the filesystem if the fs
is stored in a regular file, so that we don't have to create and
maintain separate lockfiles.

For block devices, fix a weird race between mount and unmount that is
causing testing failures by waiting a small amount of time to grab a
lock.

If you're going to start using this code, I strongly recommend pulling
from my git trees, which are linked below.

Comments and questions are, as always, welcome.

e2fsprogs git tree:
https://git.kernel.org/cgit/linux/kernel/git/djwong/e2fsprogs.git/log/?h=fuse2fs-locking
---
Commits in this patchset:
 * libext2fs: add POSIX advisory locking to the unix IO manager
 * fuse2fs: try to lock filesystem image files before using them
 * fuse2fs: quiet down write-protect warning
 * fuse2fs: try to grab block device O_EXCL repeatedly
---
 lib/ext2fs/ext2_io.h         |   12 +++-
 debian/libext2fs2t64.symbols |    2 +
 lib/ext2fs/io_manager.c      |   16 +++++
 lib/ext2fs/unix_io.c         |   71 +++++++++++++++++++++
 misc/fuse2fs.c               |  144 +++++++++++++++++++++++++++++++++++++++---
 5 files changed, 232 insertions(+), 13 deletions(-)