locking/percpu-rwsem: add freezable alternative to down_read
Percpu-rwsems are used for superblock locking. However, we know the
read percpu-rwsem we take for sb_start_write() on a frozen filesystem
needs not to inhibit system from suspending or hibernating. That
means it needs to wait with TASK_UNINTERRUPTIBLE | TASK_FREEZABLE.
Introduce a new percpu_down_read_freezable() that allows us to control
whether TASK_FREEZABLE is added to the wait flags.
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
Link: https://lore.kernel.org/r/20250327140613.25178-2-James.Bottomley@HansenPartnership.com
Signed-off-by: Christian Brauner <brauner@kernel.org>