Commit fe3e5914 authored by Gao Xiang's avatar Gao Xiang
Browse files

erofs: try to leave (de)compressed_pages on stack if possible 



For the most cases, small pclusters can be decompressed with page
arrays on stack.

Try to leave both (de)compressed_pages on stack if possible as before.

Acked-by: default avatarChao Yu <chao@kernel.org>
Signed-off-by: default avatarGao Xiang <hsiangkao@linux.alibaba.com>
Link: https://lore.kernel.org/r/20220715154203.48093-14-hsiangkao@linux.alibaba.com
parent 4f05687f

fs/erofs/zdata.c

+21 −13
Original line number Diff line number Diff line
@@ -858,6 +858,7 @@ struct z_erofs_decompress_backend { 
	struct page **compressed_pages;



	struct page **pagepool;

	unsigned int onstack_used;

};



static int z_erofs_parse_out_bvecs(struct z_erofs_decompress_backend *be)
@@ -904,14 +905,9 @@ static int z_erofs_parse_in_bvecs(struct z_erofs_decompress_backend *be, 
{

	struct z_erofs_pcluster *pcl = be->pcl;

	unsigned int pclusterpages = z_erofs_pclusterpages(pcl);

	struct page **compressed_pages;

	int i, err = 0;



	/* XXX: will have a better approach in the following commits */

	compressed_pages = kmalloc_array(pclusterpages, sizeof(struct page *),

					 GFP_KERNEL | __GFP_NOFAIL);

	*overlapped = false;



	for (i = 0; i < pclusterpages; ++i) {

		struct z_erofs_bvec *bvec = &pcl->compressed_bvecs[i];

		struct page *page = bvec->page;
@@ -922,7 +918,7 @@ static int z_erofs_parse_in_bvecs(struct z_erofs_decompress_backend *be, 
			DBG_BUGON(1);

			continue;

		}

		compressed_pages[i] = page;

		be->compressed_pages[i] = page;



		if (z_erofs_is_inline_pcluster(pcl)) {

			if (!PageUptodate(page))
@@ -953,11 +949,8 @@ static int z_erofs_parse_in_bvecs(struct z_erofs_decompress_backend *be, 
		}

	}



	if (err) {

		kfree(compressed_pages);

	if (err)

		return err;

	}

	be->compressed_pages = compressed_pages;

	return 0;

}
@@ -976,15 +969,28 @@ static int z_erofs_decompress_pcluster(struct z_erofs_decompress_backend *be, 
	mutex_lock(&pcl->lock);

	nr_pages = pcl->nr_pages;



	/* allocate (de)compressed page arrays if cannot be kept on stack */

	be->decompressed_pages = NULL;

	be->compressed_pages = NULL;

	be->onstack_used = 0;

	if (nr_pages <= Z_EROFS_ONSTACK_PAGES) {

		be->decompressed_pages = be->onstack_pages;

		be->onstack_used = nr_pages;

		memset(be->decompressed_pages, 0,

		       sizeof(struct page *) * nr_pages);

	} else {

	}



	if (pclusterpages + be->onstack_used <= Z_EROFS_ONSTACK_PAGES)

		be->compressed_pages = be->onstack_pages + be->onstack_used;



	if (!be->decompressed_pages)

		be->decompressed_pages =

			kvcalloc(nr_pages, sizeof(struct page *),

				 GFP_KERNEL | __GFP_NOFAIL);

	}

	if (!be->compressed_pages)

		be->compressed_pages =

			kvcalloc(pclusterpages, sizeof(struct page *),

				 GFP_KERNEL | __GFP_NOFAIL);



	err2 = z_erofs_parse_out_bvecs(be);

	if (err2)
@@ -1041,7 +1047,9 @@ static int z_erofs_decompress_pcluster(struct z_erofs_decompress_backend *be, 
			WRITE_ONCE(pcl->compressed_bvecs[i].page, NULL);

		}

	}

	kfree(be->compressed_pages);

	if (be->compressed_pages < be->onstack_pages ||

	    be->compressed_pages >= be->onstack_pages + Z_EROFS_ONSTACK_PAGES)

		kvfree(be->compressed_pages);



	for (i = 0; i < nr_pages; ++i) {

		page = be->decompressed_pages[i];