Commit ccaa66c8 authored by David Sterba's avatar David Sterba
Browse files

Revert "btrfs: compression: drop kmap/kunmap from lzo" 

This reverts commit 8c945d32.

The kmaps in compression code are still needed and cause crashes on
32bit machines (ARM, x86). Reproducible eg. by running fstest btrfs/004
with enabled LZO or ZSTD compression.

The revert does not apply cleanly due to changes in a6e66e6f
("btrfs: rework lzo_decompress_bio() to make it subpage compatible")
that reworked the page iteration so the revert is done to be equivalent
to the original code.

Link: https://lore.kernel.org/all/CAJCQCtT+OuemovPO7GZk8Y8=qtOObr0XTDp8jh4OHD6y84AFxw@mail.gmail.com/
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=214839


Tested-by: default avatarQu Wenruo <wqu@suse.com>
Signed-off-by: default avatarQu Wenruo <wqu@suse.com>
Signed-off-by: default avatarDavid Sterba <dsterba@suse.com>
parent 55276e14

fs/btrfs/lzo.c

+25 −11
Original line number Diff line number Diff line
@@ -141,7 +141,7 @@ int lzo_compress_pages(struct list_head *ws, struct address_space *mapping, 
	*total_in = 0;



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

	data_in = page_address(in_page);

	data_in = kmap(in_page);



	/*

	 * store the size of all chunks of compressed data in
@@ -152,7 +152,7 @@ int lzo_compress_pages(struct list_head *ws, struct address_space *mapping, 
		ret = -ENOMEM;

		goto out;

	}

	cpage_out = page_address(out_page);

	cpage_out = kmap(out_page);

	out_offset = LZO_LEN;

	tot_out = LZO_LEN;

	pages[0] = out_page;
@@ -210,6 +210,7 @@ int lzo_compress_pages(struct list_head *ws, struct address_space *mapping, 
				if (out_len == 0 && tot_in >= len)

					break;



				kunmap(out_page);

				if (nr_pages == nr_dest_pages) {

					out_page = NULL;

					ret = -E2BIG;
@@ -221,7 +222,7 @@ int lzo_compress_pages(struct list_head *ws, struct address_space *mapping, 
					ret = -ENOMEM;

					goto out;

				}

				cpage_out = page_address(out_page);

				cpage_out = kmap(out_page);

				pages[nr_pages++] = out_page;



				pg_bytes_left = PAGE_SIZE;
@@ -243,11 +244,12 @@ int lzo_compress_pages(struct list_head *ws, struct address_space *mapping, 
			break;



		bytes_left = len - tot_in;

		kunmap(in_page);

		put_page(in_page);



		start += PAGE_SIZE;

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

		data_in = page_address(in_page);

		data_in = kmap(in_page);

		in_len = min(bytes_left, PAGE_SIZE);

	}
@@ -257,17 +259,22 @@ int lzo_compress_pages(struct list_head *ws, struct address_space *mapping, 
	}



	/* store the size of all chunks of compressed data */

	sizes_ptr = page_address(pages[0]);

	sizes_ptr = kmap_local_page(pages[0]);

	write_compress_length(sizes_ptr, tot_out);

	kunmap_local(sizes_ptr);



	ret = 0;

	*total_out = tot_out;

	*total_in = tot_in;

out:

	*out_pages = nr_pages;

	if (out_page)

		kunmap(out_page);



	if (in_page)

	if (in_page) {

		kunmap(in_page);

		put_page(in_page);

	}



	return ret;

}
@@ -283,6 +290,7 @@ static void copy_compressed_segment(struct compressed_bio *cb, 
	u32 orig_in = *cur_in;



	while (*cur_in < orig_in + len) {

		char *kaddr;

		struct page *cur_page;

		u32 copy_len = min_t(u32, PAGE_SIZE - offset_in_page(*cur_in),

					  orig_in + len - *cur_in);
@@ -290,9 +298,11 @@ static void copy_compressed_segment(struct compressed_bio *cb, 
		ASSERT(copy_len);

		cur_page = cb->compressed_pages[*cur_in / PAGE_SIZE];



		kaddr = kmap(cur_page);

		memcpy(dest + *cur_in - orig_in,

			page_address(cur_page) + offset_in_page(*cur_in),

			kaddr + offset_in_page(*cur_in),

			copy_len);

		kunmap(cur_page);



		*cur_in += copy_len;

	}
@@ -303,6 +313,7 @@ int lzo_decompress_bio(struct list_head *ws, struct compressed_bio *cb) 
	struct workspace *workspace = list_entry(ws, struct workspace, list);

	const struct btrfs_fs_info *fs_info = btrfs_sb(cb->inode->i_sb);

	const u32 sectorsize = fs_info->sectorsize;

	char *kaddr;

	int ret;

	/* Compressed data length, can be unaligned */

	u32 len_in;
@@ -311,7 +322,9 @@ int lzo_decompress_bio(struct list_head *ws, struct compressed_bio *cb) 
	/* Bytes decompressed so far */

	u32 cur_out = 0;



	len_in = read_compress_length(page_address(cb->compressed_pages[0]));

	kaddr = kmap(cb->compressed_pages[0]);

	len_in = read_compress_length(kaddr);

	kunmap(cb->compressed_pages[0]);

	cur_in += LZO_LEN;



	/*
@@ -344,9 +357,9 @@ int lzo_decompress_bio(struct list_head *ws, struct compressed_bio *cb) 
		ASSERT(cur_in / sectorsize ==

		       (cur_in + LZO_LEN - 1) / sectorsize);

		cur_page = cb->compressed_pages[cur_in / PAGE_SIZE];

		kaddr = kmap(cur_page);

		ASSERT(cur_page);

		seg_len = read_compress_length(page_address(cur_page) +

					       offset_in_page(cur_in));

		seg_len = read_compress_length(kaddr + offset_in_page(cur_in));

		cur_in += LZO_LEN;



		/* Copy the compressed segment payload into workspace */
@@ -431,7 +444,7 @@ int lzo_decompress(struct list_head *ws, unsigned char *data_in, 
	destlen = min_t(unsigned long, destlen, PAGE_SIZE);

	bytes = min_t(unsigned long, destlen, out_len - start_byte);



	kaddr = page_address(dest_page);

	kaddr = kmap_local_page(dest_page);

	memcpy(kaddr, workspace->buf + start_byte, bytes);



	/*
@@ -441,6 +454,7 @@ int lzo_decompress(struct list_head *ws, unsigned char *data_in, 
	 */

	if (bytes < destlen)

		memset(kaddr+bytes, 0, destlen-bytes);

	kunmap_local(kaddr);

out:

	return ret;

}