Commit 393f42f1 authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge tag 'dax-fixes-5.13-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/nvdimm/nvdimm 

Pull dax fixes from Dan Williams:
 "A fix for a hang condition due to missed wakeups in the filesystem-dax
  core when exercised by virtiofs.

  This bug has been there from the beginning, but the condition has
  not triggered on other filesystems since they hold a lock over
  invalidation events"

* tag 'dax-fixes-5.13-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/nvdimm/nvdimm:
  dax: Wake up all waiters after invalidating dax entry
  dax: Add a wakeup mode parameter to put_unlocked_entry()
  dax: Add an enum for specifying dax wakup mode
parents 33f85ca4 23738832

fs/dax.c

+23 −12
Original line number Diff line number Diff line
@@ -144,6 +144,16 @@ struct wait_exceptional_entry_queue { 
	struct exceptional_entry_key key;

};



/**

 * enum dax_wake_mode: waitqueue wakeup behaviour

 * @WAKE_ALL: wake all waiters in the waitqueue

 * @WAKE_NEXT: wake only the first waiter in the waitqueue

 */

enum dax_wake_mode {

	WAKE_ALL,

	WAKE_NEXT,

};



static wait_queue_head_t *dax_entry_waitqueue(struct xa_state *xas,

		void *entry, struct exceptional_entry_key *key)

{
@@ -182,7 +192,8 @@ static int wake_exceptional_entry_func(wait_queue_entry_t *wait, 
 * The important information it's conveying is whether the entry at

 * this index used to be a PMD entry.

 */

static void dax_wake_entry(struct xa_state *xas, void *entry, bool wake_all)

static void dax_wake_entry(struct xa_state *xas, void *entry,

			   enum dax_wake_mode mode)

{

	struct exceptional_entry_key key;

	wait_queue_head_t *wq;
@@ -196,7 +207,7 @@ static void dax_wake_entry(struct xa_state *xas, void *entry, bool wake_all) 
	 * must be in the waitqueue and the following check will see them.

	 */

	if (waitqueue_active(wq))

		__wake_up(wq, TASK_NORMAL, wake_all ? 0 : 1, &key);

		__wake_up(wq, TASK_NORMAL, mode == WAKE_ALL ? 0 : 1, &key);

}



/*
@@ -264,11 +275,11 @@ static void wait_entry_unlocked(struct xa_state *xas, void *entry) 
	finish_wait(wq, &ewait.wait);

}



static void put_unlocked_entry(struct xa_state *xas, void *entry)

static void put_unlocked_entry(struct xa_state *xas, void *entry,

			       enum dax_wake_mode mode)

{

	/* If we were the only waiter woken, wake the next one */

	if (entry && !dax_is_conflict(entry))

		dax_wake_entry(xas, entry, false);

		dax_wake_entry(xas, entry, mode);

}



/*
@@ -286,7 +297,7 @@ static void dax_unlock_entry(struct xa_state *xas, void *entry) 
	old = xas_store(xas, entry);

	xas_unlock_irq(xas);

	BUG_ON(!dax_is_locked(old));

	dax_wake_entry(xas, entry, false);

	dax_wake_entry(xas, entry, WAKE_NEXT);

}



/*
@@ -524,7 +535,7 @@ static void *grab_mapping_entry(struct xa_state *xas, 


		dax_disassociate_entry(entry, mapping, false);

		xas_store(xas, NULL);	/* undo the PMD join */

		dax_wake_entry(xas, entry, true);

		dax_wake_entry(xas, entry, WAKE_ALL);

		mapping->nrpages -= PG_PMD_NR;

		entry = NULL;

		xas_set(xas, index);
@@ -622,7 +633,7 @@ struct page *dax_layout_busy_page_range(struct address_space *mapping, 
			entry = get_unlocked_entry(&xas, 0);

		if (entry)

			page = dax_busy_page(entry);

		put_unlocked_entry(&xas, entry);

		put_unlocked_entry(&xas, entry, WAKE_NEXT);

		if (page)

			break;

		if (++scanned % XA_CHECK_SCHED)
@@ -664,7 +675,7 @@ static int __dax_invalidate_entry(struct address_space *mapping, 
	mapping->nrpages -= 1UL << dax_entry_order(entry);

	ret = 1;

out:

	put_unlocked_entry(&xas, entry);

	put_unlocked_entry(&xas, entry, WAKE_ALL);

	xas_unlock_irq(&xas);

	return ret;

}
@@ -937,13 +948,13 @@ static int dax_writeback_one(struct xa_state *xas, struct dax_device *dax_dev, 
	xas_lock_irq(xas);

	xas_store(xas, entry);

	xas_clear_mark(xas, PAGECACHE_TAG_DIRTY);

	dax_wake_entry(xas, entry, false);

	dax_wake_entry(xas, entry, WAKE_NEXT);



	trace_dax_writeback_one(mapping->host, index, count);

	return ret;



 put_unlocked:

	put_unlocked_entry(xas, entry);

	put_unlocked_entry(xas, entry, WAKE_NEXT);

	return ret;

}
@@ -1684,7 +1695,7 @@ dax_insert_pfn_mkwrite(struct vm_fault *vmf, pfn_t pfn, unsigned int order) 
	/* Did we race with someone splitting entry or so? */

	if (!entry || dax_is_conflict(entry) ||

	    (order == 0 && !dax_is_pte_entry(entry))) {

		put_unlocked_entry(&xas, entry);

		put_unlocked_entry(&xas, entry, WAKE_NEXT);

		xas_unlock_irq(&xas);

		trace_dax_insert_pfn_mkwrite_no_entry(mapping->host, vmf,

						      VM_FAULT_NOPAGE);