Commit 51c0674a authored by Fabio M. De Francesco's avatar Fabio M. De Francesco Committed by David Sterba
Browse files

btrfs: replace kmap() with kmap_local_page() in lzo.c 



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

Therefore, use kmap_local_page() / kunmap_local() in lzo.c wherever the
mappings are per thread and not globally visible.

Tested on QEMU + KVM 32 bits VM with 4GB of RAM and HIGHMEM64G enabled.

Suggested-by: default avatarIra Weiny <ira.weiny@intel.com>
Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
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 70826b6b

fs/btrfs/lzo.c

+12 −16
Original line number Diff line number Diff line
@@ -155,7 +155,7 @@ static int copy_compressed_data_to_page(char *compressed_data, 
		out_pages[*cur_out / PAGE_SIZE] = cur_page;

	}



	kaddr = kmap(cur_page);

	kaddr = kmap_local_page(cur_page);

	write_compress_length(kaddr + offset_in_page(*cur_out),

			      compressed_size);

	*cur_out += LZO_LEN;
@@ -167,7 +167,7 @@ static int copy_compressed_data_to_page(char *compressed_data, 
		u32 copy_len = min_t(u32, sectorsize - *cur_out % sectorsize,

				     orig_out + compressed_size - *cur_out);



		kunmap(cur_page);

		kunmap_local(kaddr);



		if ((*cur_out / PAGE_SIZE) >= max_nr_page)

			return -E2BIG;
@@ -180,7 +180,7 @@ static int copy_compressed_data_to_page(char *compressed_data, 
				return -ENOMEM;

			out_pages[*cur_out / PAGE_SIZE] = cur_page;

		}

		kaddr = kmap(cur_page);

		kaddr = kmap_local_page(cur_page);



		memcpy(kaddr + offset_in_page(*cur_out),

		       compressed_data + *cur_out - orig_out, copy_len);
@@ -202,7 +202,7 @@ static int copy_compressed_data_to_page(char *compressed_data, 
	*cur_out += sector_bytes_left;



out:

	kunmap(cur_page);

	kunmap_local(kaddr);

	return 0;

}
@@ -248,12 +248,12 @@ int lzo_compress_pages(struct list_head *ws, struct address_space *mapping, 
		/* Compress at most one sector of data each time */

		in_len = min_t(u32, start + len - cur_in, sectorsize - sector_off);

		ASSERT(in_len);

		data_in = kmap(page_in);

		data_in = kmap_local_page(page_in);

		ret = lzo1x_1_compress(data_in +

				       offset_in_page(cur_in), in_len,

				       workspace->cbuf, &out_len,

				       workspace->mem);

		kunmap(page_in);

		kunmap_local(data_in);

		if (ret < 0) {

			pr_debug("BTRFS: lzo in loop returned %d\n", ret);

			ret = -EIO;
@@ -310,7 +310,6 @@ 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);
@@ -318,11 +317,8 @@ 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,

			kaddr + offset_in_page(*cur_in),

			copy_len);

		kunmap(cur_page);

		memcpy_from_page(dest + *cur_in - orig_in, cur_page,

				 offset_in_page(*cur_in), copy_len);



		*cur_in += copy_len;

	}
@@ -342,9 +338,9 @@ int lzo_decompress_bio(struct list_head *ws, struct compressed_bio *cb) 
	/* Bytes decompressed so far */

	u32 cur_out = 0;



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

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

	len_in = read_compress_length(kaddr);

	kunmap(cb->compressed_pages[0]);

	kunmap_local(kaddr);

	cur_in += LZO_LEN;



	/*
@@ -378,9 +374,9 @@ int lzo_decompress_bio(struct list_head *ws, struct compressed_bio *cb) 
		       (cur_in + LZO_LEN - 1) / sectorsize);

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

		ASSERT(cur_page);

		kaddr = kmap(cur_page);

		kaddr = kmap_local_page(cur_page);

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

		kunmap(cur_page);

		kunmap_local(kaddr);

		cur_in += LZO_LEN;



		if (seg_len > WORKSPACE_CBUF_LENGTH) {