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Commit e4b3448b authored by Matthew Wilcox's avatar Matthew Wilcox Committed by Dan Williams
Browse files

dax: Flush partial PMDs correctly 



The radix tree would rewind the index in an iterator to the lowest index
of a multi-slot entry.  The XArray iterators instead leave the index
unchanged, but I overlooked that when converting DAX from the radix tree
to the XArray.  Adjust the index that we use for flushing to the start
of the PMD range.

Fixes: c1901cd3 ("page cache: Convert find_get_entries_tag to XArray")
Cc: <stable@vger.kernel.org>
Reported-by: default avatarPiotr Balcer <piotr.balcer@intel.com>
Tested-by: default avatarDan Williams <dan.j.williams@intel.com>
Reviewed-by: default avatarJan Kara <jack@suse.cz>
Signed-off-by: default avatarMatthew Wilcox <willy@infradead.org>
Signed-off-by: default avatarDan Williams <dan.j.williams@intel.com>
parent 0cefc36b

fs/dax.c

+9 −10
Original line number Diff line number Diff line
@@ -843,9 +843,8 @@ static void dax_entry_mkclean(struct address_space *mapping, pgoff_t index, 
static int dax_writeback_one(struct xa_state *xas, struct dax_device *dax_dev,

		struct address_space *mapping, void *entry)

{

	unsigned long pfn;

	unsigned long pfn, index, count;

	long ret = 0;

	size_t size;



	/*

	 * A page got tagged dirty in DAX mapping? Something is seriously
@@ -894,17 +893,18 @@ static int dax_writeback_one(struct xa_state *xas, struct dax_device *dax_dev, 
	xas_unlock_irq(xas);



	/*

	 * Even if dax_writeback_mapping_range() was given a wbc->range_start

	 * in the middle of a PMD, the 'index' we are given will be aligned to

	 * the start index of the PMD, as will the pfn we pull from 'entry'.

	 * If dax_writeback_mapping_range() was given a wbc->range_start

	 * in the middle of a PMD, the 'index' we use needs to be

	 * aligned to the start of the PMD.

	 * This allows us to flush for PMD_SIZE and not have to worry about

	 * partial PMD writebacks.

	 */

	pfn = dax_to_pfn(entry);

	size = PAGE_SIZE << dax_entry_order(entry);

	count = 1UL << dax_entry_order(entry);

	index = xas->xa_index & ~(count - 1);



	dax_entry_mkclean(mapping, xas->xa_index, pfn);

	dax_flush(dax_dev, page_address(pfn_to_page(pfn)), size);

	dax_entry_mkclean(mapping, index, pfn);

	dax_flush(dax_dev, page_address(pfn_to_page(pfn)), count * PAGE_SIZE);

	/*

	 * After we have flushed the cache, we can clear the dirty tag. There

	 * cannot be new dirty data in the pfn after the flush has completed as
@@ -917,8 +917,7 @@ static int dax_writeback_one(struct xa_state *xas, struct dax_device *dax_dev, 
	xas_clear_mark(xas, PAGECACHE_TAG_DIRTY);

	dax_wake_entry(xas, entry, false);



	trace_dax_writeback_one(mapping->host, xas->xa_index,

			size >> PAGE_SHIFT);

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

	return ret;



 put_unlocked: