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: Ira Weiny <ira.weiny@intel.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Fabio M. De Francesco <fmdefrancesco@gmail.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/fs/btrfs/lzo.c b/fs/btrfs/lzo.c
index 430ad36b8b08023bc7b9236bf2d9ae0209857ba4..89bc5f825e0a6a99128e29b2f6b82ccb3d86b81a 100644 (file)
--- a/fs/btrfs/lzo.c
+++ b/fs/btrfs/lzo.c
@@ -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) {