Commit 718e5855 authored by Fabio M. De Francesco's avatar Fabio M. De Francesco Committed by David Sterba
Browse files

btrfs: zlib: replace kmap() with kmap_local_page() in zlib_compress_pages() 



The use of kmap() is being deprecated in favor of kmap_local_page(). With
kmap_local_page(), the mapping is per thread, CPU local and not globally
visible.

Therefore, use kmap_local_page() / kunmap_local() in zlib_compress_pages()
because in this function the mappings are per thread and are not visible
in other contexts. Furthermore, drop the mappings of "out_page" which is
allocated within zlib_compress_pages() with alloc_page(GFP_NOFS) and use
page_address().

Tested with xfstests on a QEMU + KVM 32-bits VM with 4GB of RAM booting
a kernel with HIGHMEM64G enabled. This patch passes 26/26 tests of group
"compress".

CC: Qu Wenruo <wqu@suse.com>
Suggested-by: default avatarIra Weiny <ira.weiny@intel.com>
Reviewed-by: default avatarIra Weiny <ira.weiny@intel.com>
Signed-off-by: default avatarFabio M. De Francesco <fmdefrancesco@gmail.com>
Reviewed-by: default avatarDavid Sterba <dsterba@suse.com>
Signed-off-by: default avatarDavid Sterba <dsterba@suse.com>
parent ebd23482

fs/btrfs/zlib.c

+13 −19
Original line number Diff line number Diff line
@@ -97,7 +97,7 @@ int zlib_compress_pages(struct list_head *ws, struct address_space *mapping, 
{

	struct workspace *workspace = list_entry(ws, struct workspace, list);

	int ret;

	char *data_in;

	char *data_in = NULL;

	char *cpage_out;

	int nr_pages = 0;

	struct page *in_page = NULL;
@@ -126,7 +126,7 @@ int zlib_compress_pages(struct list_head *ws, struct address_space *mapping, 
		ret = -ENOMEM;

		goto out;

	}

	cpage_out = kmap(out_page);

	cpage_out = page_address(out_page);

	pages[0] = out_page;

	nr_pages = 1;
@@ -148,26 +148,26 @@ int zlib_compress_pages(struct list_head *ws, struct address_space *mapping, 
				int i;



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

					if (in_page) {

						kunmap(in_page);

					if (data_in) {

						kunmap_local(data_in);

						put_page(in_page);

					}

					in_page = find_get_page(mapping,

								start >> PAGE_SHIFT);

					data_in = kmap(in_page);

					data_in = kmap_local_page(in_page);

					memcpy(workspace->buf + i * PAGE_SIZE,

					       data_in, PAGE_SIZE);

					start += PAGE_SIZE;

				}

				workspace->strm.next_in = workspace->buf;

			} else {

				if (in_page) {

					kunmap(in_page);

				if (data_in) {

					kunmap_local(data_in);

					put_page(in_page);

				}

				in_page = find_get_page(mapping,

							start >> PAGE_SHIFT);

				data_in = kmap(in_page);

				data_in = kmap_local_page(in_page);

				start += PAGE_SIZE;

				workspace->strm.next_in = data_in;

			}
@@ -196,9 +196,7 @@ int zlib_compress_pages(struct list_head *ws, struct address_space *mapping, 
		 * the stream end if required

		 */

		if (workspace->strm.avail_out == 0) {

			kunmap(out_page);

			if (nr_pages == nr_dest_pages) {

				out_page = NULL;

				ret = -E2BIG;

				goto out;

			}
@@ -207,7 +205,7 @@ int zlib_compress_pages(struct list_head *ws, struct address_space *mapping, 
				ret = -ENOMEM;

				goto out;

			}

			cpage_out = kmap(out_page);

			cpage_out = page_address(out_page);

			pages[nr_pages] = out_page;

			nr_pages++;

			workspace->strm.avail_out = PAGE_SIZE;
@@ -234,9 +232,7 @@ int zlib_compress_pages(struct list_head *ws, struct address_space *mapping, 
			goto out;

		} else if (workspace->strm.avail_out == 0) {

			/* get another page for the stream end */

			kunmap(out_page);

			if (nr_pages == nr_dest_pages) {

				out_page = NULL;

				ret = -E2BIG;

				goto out;

			}
@@ -245,7 +241,7 @@ int zlib_compress_pages(struct list_head *ws, struct address_space *mapping, 
				ret = -ENOMEM;

				goto out;

			}

			cpage_out = kmap(out_page);

			cpage_out = page_address(out_page);

			pages[nr_pages] = out_page;

			nr_pages++;

			workspace->strm.avail_out = PAGE_SIZE;
@@ -264,13 +260,11 @@ int zlib_compress_pages(struct list_head *ws, struct address_space *mapping, 
	*total_in = workspace->strm.total_in;

out:

	*out_pages = nr_pages;

	if (out_page)

		kunmap(out_page);



	if (in_page) {

		kunmap(in_page);

	if (data_in) {

		kunmap_local(data_in);

		put_page(in_page);

	}



	return ret;

}