Unverified Commit cb5db358 authored by Mateusz Guzik's avatar Mateusz Guzik Committed by Christian Brauner
Browse files

fs: spell out fenced ->i_state accesses with explicit smp_wmb/smp_rmb 



The incomming helpers don't ship with _release/_acquire variants, for
the time being anyway.

Signed-off-by: default avatarMateusz Guzik <mjguzik@gmail.com>
Signed-off-by: default avatarChristian Brauner <brauner@kernel.org>
parent af6023e2

fs/fs-writeback.c

+3 −2
Original line number Diff line number Diff line
@@ -476,10 +476,11 @@ static bool inode_do_switch_wbs(struct inode *inode, 
	switched = true;

skip_switch:

	/*

	 * Paired with load_acquire in unlocked_inode_to_wb_begin() and

	 * Paired with an acquire fence in unlocked_inode_to_wb_begin() and

	 * ensures that the new wb is visible if they see !I_WB_SWITCH.

	 */

	smp_store_release(&inode->i_state, inode->i_state & ~I_WB_SWITCH);

	smp_wmb();

	inode->i_state &= ~I_WB_SWITCH;



	xa_unlock_irq(&mapping->i_pages);

	spin_unlock(&inode->i_lock);

include/linux/backing-dev.h

+3 −2
Original line number Diff line number Diff line
@@ -277,10 +277,11 @@ unlocked_inode_to_wb_begin(struct inode *inode, struct wb_lock_cookie *cookie) 
	rcu_read_lock();



	/*

	 * Paired with store_release in inode_switch_wbs_work_fn() and

	 * Paired with a release fence in inode_do_switch_wbs() and

	 * ensures that we see the new wb if we see cleared I_WB_SWITCH.

	 */

	cookie->locked = smp_load_acquire(&inode->i_state) & I_WB_SWITCH;

	cookie->locked = inode->i_state & I_WB_SWITCH;

	smp_rmb();



	if (unlikely(cookie->locked))

		xa_lock_irqsave(&inode->i_mapping->i_pages, cookie->flags);