For now that code just return true
Later more complex heuristic code will be added
Signed-off-by: Timofey Titovets <nefelim4ag@xxxxxxxxx>
---
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
--
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