Commit ebd23482 authored by Fabio M. De Francesco's avatar Fabio M. De Francesco Committed by David Sterba
Browse files

btrfs: zstd: replace kmap() with kmap_local_page() 



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 zstd.c because in this
file the mappings are per thread and are not visible in other contexts. In
the meanwhile use plain page_address() on output pages allocated with
the GFP_NOFS flag instead of calling kmap*() on them (since they are
always allocated from ZONE_NORMAL).

Tested with xfstests on QEMU + KVM 32 bits VM with 4GB of RAM, booting a
kernel with HIGHMEM64G enabled.

Suggested-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 39ade048

fs/btrfs/zstd.c

+13 −20
Original line number Diff line number Diff line
@@ -403,7 +403,7 @@ int zstd_compress_pages(struct list_head *ws, struct address_space *mapping, 


	/* map in the first page of input data */

	in_page = find_get_page(mapping, start >> PAGE_SHIFT);

	workspace->in_buf.src = kmap(in_page);

	workspace->in_buf.src = kmap_local_page(in_page);

	workspace->in_buf.pos = 0;

	workspace->in_buf.size = min_t(size_t, len, PAGE_SIZE);
@@ -415,7 +415,7 @@ int zstd_compress_pages(struct list_head *ws, struct address_space *mapping, 
		goto out;

	}

	pages[nr_pages++] = out_page;

	workspace->out_buf.dst = kmap(out_page);

	workspace->out_buf.dst = page_address(out_page);

	workspace->out_buf.pos = 0;

	workspace->out_buf.size = min_t(size_t, max_out, PAGE_SIZE);
@@ -450,9 +450,7 @@ int zstd_compress_pages(struct list_head *ws, struct address_space *mapping, 
		if (workspace->out_buf.pos == workspace->out_buf.size) {

			tot_out += PAGE_SIZE;

			max_out -= PAGE_SIZE;

			kunmap(out_page);

			if (nr_pages == nr_dest_pages) {

				out_page = NULL;

				ret = -E2BIG;

				goto out;

			}
@@ -462,7 +460,7 @@ int zstd_compress_pages(struct list_head *ws, struct address_space *mapping, 
				goto out;

			}

			pages[nr_pages++] = out_page;

			workspace->out_buf.dst = kmap(out_page);

			workspace->out_buf.dst = page_address(out_page);

			workspace->out_buf.pos = 0;

			workspace->out_buf.size = min_t(size_t, max_out,

							PAGE_SIZE);
@@ -477,13 +475,12 @@ int zstd_compress_pages(struct list_head *ws, struct address_space *mapping, 
		/* Check if we need more input */

		if (workspace->in_buf.pos == workspace->in_buf.size) {

			tot_in += PAGE_SIZE;

			kunmap(in_page);

			kunmap_local(workspace->in_buf.src);

			put_page(in_page);



			start += PAGE_SIZE;

			len -= PAGE_SIZE;

			in_page = find_get_page(mapping, start >> PAGE_SHIFT);

			workspace->in_buf.src = kmap(in_page);

			workspace->in_buf.src = kmap_local_page(in_page);

			workspace->in_buf.pos = 0;

			workspace->in_buf.size = min_t(size_t, len, PAGE_SIZE);

		}
@@ -510,9 +507,7 @@ int zstd_compress_pages(struct list_head *ws, struct address_space *mapping, 


		tot_out += PAGE_SIZE;

		max_out -= PAGE_SIZE;

		kunmap(out_page);

		if (nr_pages == nr_dest_pages) {

			out_page = NULL;

			ret = -E2BIG;

			goto out;

		}
@@ -522,7 +517,7 @@ int zstd_compress_pages(struct list_head *ws, struct address_space *mapping, 
			goto out;

		}

		pages[nr_pages++] = out_page;

		workspace->out_buf.dst = kmap(out_page);

		workspace->out_buf.dst = page_address(out_page);

		workspace->out_buf.pos = 0;

		workspace->out_buf.size = min_t(size_t, max_out, PAGE_SIZE);

	}
@@ -537,13 +532,10 @@ int zstd_compress_pages(struct list_head *ws, struct address_space *mapping, 
	*total_out = tot_out;

out:

	*out_pages = nr_pages;

	/* Cleanup */

	if (in_page) {

		kunmap(in_page);

	if (workspace->in_buf.src) {

		kunmap_local(workspace->in_buf.src);

		put_page(in_page);

	}

	if (out_page)

		kunmap(out_page);

	return ret;

}
@@ -567,7 +559,7 @@ int zstd_decompress_bio(struct list_head *ws, struct compressed_bio *cb) 
		goto done;

	}



	workspace->in_buf.src = kmap(pages_in[page_in_index]);

	workspace->in_buf.src = kmap_local_page(pages_in[page_in_index]);

	workspace->in_buf.pos = 0;

	workspace->in_buf.size = min_t(size_t, srclen, PAGE_SIZE);
@@ -603,14 +595,15 @@ int zstd_decompress_bio(struct list_head *ws, struct compressed_bio *cb) 
			break;



		if (workspace->in_buf.pos == workspace->in_buf.size) {

			kunmap(pages_in[page_in_index++]);

			kunmap_local(workspace->in_buf.src);

			page_in_index++;

			if (page_in_index >= total_pages_in) {

				workspace->in_buf.src = NULL;

				ret = -EIO;

				goto done;

			}

			srclen -= PAGE_SIZE;

			workspace->in_buf.src = kmap(pages_in[page_in_index]);

			workspace->in_buf.src = kmap_local_page(pages_in[page_in_index]);

			workspace->in_buf.pos = 0;

			workspace->in_buf.size = min_t(size_t, srclen, PAGE_SIZE);

		}
@@ -619,7 +612,7 @@ int zstd_decompress_bio(struct list_head *ws, struct compressed_bio *cb) 
	zero_fill_bio(cb->orig_bio);

done:

	if (workspace->in_buf.src)

		kunmap(pages_in[page_in_index]);

		kunmap_local(workspace->in_buf.src);

	return ret;

}