Copy sample data from input data range to sample buffer then calculate byte type count for that sample into bucket.
Signed-off-by: Timofey Titovets <[email protected]> --- fs/btrfs/heuristic.c | 31 +++++++++++++++++++++++++++++-- 1 file changed, 29 insertions(+), 2 deletions(-) diff --git a/fs/btrfs/heuristic.c b/fs/btrfs/heuristic.c index 2c2cadc9dfad..5336638a3b7c 100644 --- a/fs/btrfs/heuristic.c +++ b/fs/btrfs/heuristic.c @@ -76,20 +76,47 @@ static struct list_head *heuristic_alloc_workspace(void) static int heuristic(struct list_head *ws, struct inode *inode, u64 start, u64 end) { + struct workspace *workspace = list_entry(ws, struct workspace, list); struct page *page; u64 index, index_end; - u8 *input_data; + u8 *in_data; + u32 a, b; + u8 byte; + + /* + * Compression only handle first 128kb of input range + * And just shift over range in loop for compressing it. + * Let's do the same. + */ + if (end - start > BTRFS_MAX_UNCOMPRESSED) + end = start + BTRFS_MAX_UNCOMPRESSED; index = start >> PAGE_SHIFT; index_end = end >> PAGE_SHIFT; + b = 0; for (; index <= index_end; index++) { page = find_get_page(inode->i_mapping, index); - input_data = kmap(page); + in_data = kmap(page); + a = 0; + while (a < PAGE_SIZE-READ_SIZE && b < MAX_SAMPLE_SIZE) { + memcpy(&workspace->sample[b], &in_data[a], READ_SIZE); + a += ITER_SHIFT; + b += READ_SIZE; + } kunmap(page); put_page(page); } + workspace->sample_size = b; + + memset(workspace->bucket, 0, sizeof(*workspace->bucket)*BUCKET_SIZE); + + for (a = 0; a < workspace->sample_size; a++) { + byte = workspace->sample[a]; + workspace->bucket[byte].count++; + } + return 1; } -- 2.14.1 -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
