This sequence is posted as an RFC because it needs to be combined with Luis' patch set: https://lore.kernel.org/linux-fsdevel/20250326112220.1988619-1-mcgrof@xxxxxxxxxx/ In particular I've done nothing to replace the kthread freezing in filesystems. I can say that this works flawlessly on 6.14 with my limited test rig (I only have access to my laptop while at LSF/MM). My test VM is ext4 root with a file on the root attached to a loop device and mounted (to test nesting) while running a fio workload on the upper ext4. The rwsem rework is absolutely necessary because without it hibernate immediately fails because systemd-journald tries to record the kernel messages and gets blocked in sb_start_write() on TASK_INTERRUPTIBLE which inhibits hibernation. My goal in doing this is to be able to add a thaw_super() callback to efivarfs and remove our deadlock prone pm notifier. Regards, James --- James Bottomley (4): locking/percpu-rwsem: add freezable alternative to down_read vfs: make sb_start_write freezable fs/super.c: introduce reverse superblock iterator and use it in emergency remount vfs: add filesystem freeze/thaw callbacks for power management fs/super.c | 109 ++++++++++++++++++++++++++++------ include/linux/fs.h | 8 ++- include/linux/percpu-rwsem.h | 20 +++++-- kernel/locking/percpu-rwsem.c | 13 ++-- kernel/power/hibernate.c | 12 ++++ kernel/power/suspend.c | 4 ++ 6 files changed, 137 insertions(+), 29 deletions(-) -- 2.43.0
