diff options
author | Darrick J. Wong <djwong@kernel.org> | 2023-07-17 18:00:09 +0200 |
---|---|---|
committer | Darrick J. Wong <djwong@kernel.org> | 2023-07-17 18:00:09 +0200 |
commit | 880b9577855edddda1e732748e849c63199d489b (patch) | |
tree | 8864baba5793708725a2c440be96c218846eeaef /Documentation/leds/leds-mlxcpld.rst | |
parent | Linux 6.5-rc2 (diff) | |
download | linux-880b9577855edddda1e732748e849c63199d489b.tar.xz linux-880b9577855edddda1e732748e849c63199d489b.zip |
fs: distinguish between user initiated freeze and kernel initiated freeze
Userspace can freeze a filesystem using the FIFREEZE ioctl or by
suspending the block device; this state persists until userspace thaws
the filesystem with the FITHAW ioctl or resuming the block device.
Since commit 18e9e5104fcd ("Introduce freeze_super and thaw_super for
the fsfreeze ioctl") we only allow the first freeze command to succeed.
The kernel may decide that it is necessary to freeze a filesystem for
its own internal purposes, such as suspends in progress, filesystem fsck
activities, or quiescing a device prior to removal. Userspace thaw
commands must never break a kernel freeze, and kernel thaw commands
shouldn't undo userspace's freeze command.
Introduce a couple of freeze holder flags and wire it into the
sb_writers state. One kernel and one userspace freeze are allowed to
coexist at the same time; the filesystem will not thaw until both are
lifted.
I wonder if the f2fs/gfs2 code should be using a kernel freeze here, but
for now we'll use FREEZE_HOLDER_USERSPACE to preserve existing
behaviors.
Cc: mcgrof@kernel.org
Cc: jack@suse.cz
Cc: hch@infradead.org
Cc: ruansy.fnst@fujitsu.com
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Diffstat (limited to 'Documentation/leds/leds-mlxcpld.rst')
0 files changed, 0 insertions, 0 deletions