For now that code just return true Later more complex heuristic code will be added
Signed-off-by: Timofey Titovets <nefelim...@gmail.com> --- fs/btrfs/compression.c | 30 ++++++++++++++++++++++++++++++ fs/btrfs/compression.h | 2 ++ fs/btrfs/inode.c | 10 +++++----- 3 files changed, 37 insertions(+), 5 deletions(-) diff --git a/fs/btrfs/compression.c b/fs/btrfs/compression.c index d2ef9ac2a630..27ba11a74eb2 100644 --- a/fs/btrfs/compression.c +++ b/fs/btrfs/compression.c @@ -1047,3 +1047,33 @@ int btrfs_decompress_buf2page(const char *buf, unsigned long buf_start, return 1; } + +/* + * Heuristic skeleton + * For now just would be a naive and very optimistic 'return true'. + * Heuristic proporsed to fast (in compare to direct compression) detect + * data type (compressible/uncompressible) for avoid vaste of cpu time + * on compression uncompressible data. + * In near time that logic will be added: + * 0. Get sample of input data + * 1. Detect Mostly Zeroed data + * 2. Detect Data with low "byte set" size (Text & etc) + * 3. Detect Data with low/high core "byte set" + */ +int btrfs_compress_heuristic(struct inode *inode, u64 start, u64 end) +{ + u64 index = start >> PAGE_SHIFT; + u64 end_index = end >> PAGE_SHIFT; + struct page *page; + int ret = 1; + + while (index <= end_index) { + page = find_get_page(inode->i_mapping, index); + kmap(page); + kunmap(page); + put_page(page); + index++; + } + + return ret; +} diff --git a/fs/btrfs/compression.h b/fs/btrfs/compression.h index 87f6d3332163..8508ba6b9aef 100644 --- a/fs/btrfs/compression.h +++ b/fs/btrfs/compression.h @@ -129,4 +129,6 @@ struct btrfs_compress_op { extern const struct btrfs_compress_op btrfs_zlib_compress; extern const struct btrfs_compress_op btrfs_lzo_compress; +int btrfs_compress_heuristic(struct inode *inode, u64 start, u64 end); + #endif diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c index 95c212037095..c23b7047fc39 100644 --- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -392,20 +392,20 @@ static noinline int add_async_extent(struct async_cow *cow, return 0; } -static inline int inode_need_compress(struct inode *inode) +static inline int inode_need_compress(struct inode *inode, u64 start, u64 end) { struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb); /* force compress */ if (btrfs_test_opt(fs_info, FORCE_COMPRESS)) - return 1; + return btrfs_compress_heuristic(inode, start, end); /* bad compression ratios */ if (BTRFS_I(inode)->flags & BTRFS_INODE_NOCOMPRESS) return 0; if (btrfs_test_opt(fs_info, COMPRESS) || BTRFS_I(inode)->flags & BTRFS_INODE_COMPRESS || BTRFS_I(inode)->force_compress) - return 1; + return btrfs_compress_heuristic(inode, start, end); return 0; } @@ -503,7 +503,7 @@ static noinline void compress_file_range(struct inode *inode, * inode has not been flagged as nocompress. This flag can * change at any time if we discover bad compression ratios. */ - if (inode_need_compress(inode)) { + if (inode_need_compress(inode, start, end)) { WARN_ON(pages); pages = kcalloc(nr_pages, sizeof(struct page *), GFP_NOFS); if (!pages) { @@ -1576,7 +1576,7 @@ static int run_delalloc_range(void *private_data, struct page *locked_page, } else if (BTRFS_I(inode)->flags & BTRFS_INODE_PREALLOC && !force_cow) { ret = run_delalloc_nocow(inode, locked_page, start, end, page_started, 0, nr_written); - } else if (!inode_need_compress(inode)) { + } else if (!inode_need_compress(inode, start, end)) { ret = cow_file_range(inode, locked_page, start, end, end, page_started, nr_written, 1, NULL); } else { -- 2.13.3 -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html