Commit 5d899d43 authored by Christoph Hellwig's avatar Christoph Hellwig Committed by Andrew Morton
Browse files

writeback: only update ->writeback_index for range_cyclic writeback 

mapping->writeback_index is only [1] used as the starting point for
range_cyclic writeback, so there is no point in updating it for other
types of writeback.

[1] except for btrfs_defrag_file which does really odd things with
mapping->writeback_index.  But btrfs doesn't use write_cache_pages at all,
so this isn't relevant here.

Link: https://lkml.kernel.org/r/20240215063649.2164017-6-hch@lst.de


Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
Reviewed-by: default avatarBrian Foster <bfoster@redhat.com>
Reviewed-by: default avatarJan Kara <jack@suse.cz>
Acked-by: default avatarDave Chinner <dchinner@redhat.com>
Cc: Christian Brauner <brauner@kernel.org>
Cc: David Howells <dhowells@redhat.com>
Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 98103258

mm/page-writeback.c

+14 −10
Original line number Diff line number Diff line
@@ -2403,7 +2403,6 @@ int write_cache_pages(struct address_space *mapping, 
	pgoff_t index;

	pgoff_t end;		/* Inclusive */

	pgoff_t done_index;

	int range_whole = 0;

	xa_mark_t tag;



	folio_batch_init(&fbatch);
@@ -2413,8 +2412,6 @@ int write_cache_pages(struct address_space *mapping, 
	} else {

		index = wbc->range_start >> PAGE_SHIFT;

		end = wbc->range_end >> PAGE_SHIFT;

		if (wbc->range_start == 0 && wbc->range_end == LLONG_MAX)

			range_whole = 1;

	}

	if (wbc->sync_mode == WB_SYNC_ALL || wbc->tagged_writepages) {

		tag_pages_for_writeback(mapping, index, end);
@@ -2518,14 +2515,21 @@ int write_cache_pages(struct address_space *mapping, 
	}



	/*

	 * If we hit the last page and there is more work to be done: wrap

	 * back the index back to the start of the file for the next

	 * time we are called.

	 * For range cyclic writeback we need to remember where we stopped so

	 * that we can continue there next time we are called.  If  we hit the

	 * last page and there is more work to be done, wrap back to the start

	 * of the file.

	 *

	 * For non-cyclic writeback we always start looking up at the beginning

	 * of the file if we are called again, which can only happen due to

	 * -ENOMEM from the file system.

	 */

	if (wbc->range_cyclic && !done)

		done_index = 0;

	if (wbc->range_cyclic || (range_whole && wbc->nr_to_write > 0))

	if (wbc->range_cyclic) {

		if (done)

			mapping->writeback_index = done_index;

		else

			mapping->writeback_index = 0;

	}



	return ret;

}