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

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_decompress_bio()
because in this function the mappings are per thread and are not visible
in other contexts.

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

Suggested-by: Ira Weiny <ira.weiny@intel.com>
Reviewed-by: Ira Weiny <ira.weiny@intel.com>
Reviewed-by: Qu Wenruo <wqu@suse.com>
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/zlib.c b/fs/btrfs/zlib.c
index 82a43ac..b4f4466 100644 (file)
--- a/fs/btrfs/zlib.c
+++ b/fs/btrfs/zlib.c
@@ -281,7 +281,7 @@ int zlib_decompress_bio(struct list_head *ws, struct compressed_bio *cb)
        unsigned long buf_start;
        struct page **pages_in = cb->compressed_pages;
 
-       data_in = kmap(pages_in[page_in_index]);
+       data_in = kmap_local_page(pages_in[page_in_index]);
        workspace->strm.next_in = data_in;
        workspace->strm.avail_in = min_t(size_t, srclen, PAGE_SIZE);
        workspace->strm.total_in = 0;
@@ -303,7 +303,7 @@ int zlib_decompress_bio(struct list_head *ws, struct compressed_bio *cb)
 
        if (Z_OK != zlib_inflateInit2(&workspace->strm, wbits)) {
                pr_warn("BTRFS: inflateInit failed\n");
-               kunmap(pages_in[page_in_index]);
+               kunmap_local(data_in);
                return -EIO;
        }
        while (workspace->strm.total_in < srclen) {
@@ -330,13 +330,13 @@ int zlib_decompress_bio(struct list_head *ws, struct compressed_bio *cb)
 
                if (workspace->strm.avail_in == 0) {
                        unsigned long tmp;
-                       kunmap(pages_in[page_in_index]);
+                       kunmap_local(data_in);
                        page_in_index++;
                        if (page_in_index >= total_pages_in) {
                                data_in = NULL;
                                break;
                        }
-                       data_in = kmap(pages_in[page_in_index]);
+                       data_in = kmap_local_page(pages_in[page_in_index]);
                        workspace->strm.next_in = data_in;
                        tmp = srclen - workspace->strm.total_in;
                        workspace->strm.avail_in = min(tmp, PAGE_SIZE);
@@ -349,7 +349,7 @@ int zlib_decompress_bio(struct list_head *ws, struct compressed_bio *cb)
 done:
        zlib_inflateEnd(&workspace->strm);
        if (data_in)
-               kunmap(pages_in[page_in_index]);
+               kunmap_local(data_in);
        if (!ret)
                zero_fill_bio(cb->orig_bio);
        return ret;