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 <nefelim...@gmail.com>
---
fs/btrfs/compression.c | 71 +++++++++++++++++++++++++++++++++++++++++++-------
1 file changed, 61 insertions(+), 10 deletions(-)
diff --git a/fs/btrfs/compression.c b/fs/btrfs/compression.c
index 1715655d050e..e2419639ae7f 100644
--- a/fs/btrfs/compression.c
+++ b/fs/btrfs/compression.c
@@ -725,7 +725,6 @@ blk_status_t btrfs_submit_compressed_read(struct inode
*inode, struct bio *bio,
#define MAX_SAMPLE_SIZE (BTRFS_MAX_UNCOMPRESSED * \
SAMPLING_READ_SIZE / SAMPLING_INTERVAL)
-
struct bucket_item {
u32 count;
};
@@ -733,6 +732,7 @@ struct bucket_item {
struct heuristic_ws {
/* Partial copy of input data */
u8 *sample;
+ u32 sample_size;
/* Bucket store counter for each byte type */
struct bucket_item *bucket;
struct list_head list;
@@ -1200,6 +1200,57 @@ int btrfs_decompress_buf2page(const char *buf, unsigned
long buf_start,
return 1;
}
+static void heuristic_collect_sample(struct inode *inode, u64 start, u64 end,
+ struct heuristic_ws *ws)
+{
+ struct page *page;
+ u64 index, index_end;
+ u32 i, curr_sample_pos;
+ u8 *in_data;
+
+ /*
+ * Compression only handle first 128kb of input range
+ * And just shift over range in loop for compressing it.
+ * Let's do the same.
+ *
+ * MAX_SAMPLE_SIZE - calculated in assume that heuristic will process
+ * not more then BTRFS_MAX_UNCOMPRESSED at run
+ */
+ if (end - start > BTRFS_MAX_UNCOMPRESSED)
+ end = start + BTRFS_MAX_UNCOMPRESSED;
+
+ index = start >> PAGE_SHIFT;
+ index_end = end >> PAGE_SHIFT;
+
+ /* Don't miss unaligned end */
+ if (!IS_ALIGNED(end, PAGE_SIZE))
+ index_end++;
+
+ curr_sample_pos = 0;
+ while (index < index_end) {
+ page = find_get_page(inode->i_mapping, index);
+ in_data = kmap(page);
+ /* Handle case where start unaligned to PAGE_SIZE */
+ i = start % PAGE_SIZE;
+ while (i < PAGE_SIZE - SAMPLING_READ_SIZE) {
+ /* Don't sample mem trash from last page */
+ if (start > end - SAMPLING_READ_SIZE)
+ break;
+ memcpy(&ws->sample[curr_sample_pos],
+ &in_data[i], SAMPLING_READ_SIZE);
+ i += SAMPLING_INTERVAL;
+ start += SAMPLING_INTERVAL;
+ curr_sample_pos += SAMPLING_READ_SIZE;
+ }
+ kunmap(page);
+ put_page(page);
+
+ index++;
+ }
+
+ ws->sample_size = curr_sample_pos;
+}
+
/*
* Compression heuristic.
*
@@ -1219,19 +1270,19 @@ int btrfs_compress_heuristic(struct inode *inode, u64
start, u64 end)
{
struct list_head *ws_list = __find_workspace(0, true);
struct heuristic_ws *ws;
- u64 index = start >> PAGE_SHIFT;
- u64 end_index = end >> PAGE_SHIFT;
- struct page *page;
+ u32 i;
+ u8 byte;
int ret = 1;
ws = list_entry(ws_list, struct heuristic_ws, list);
- while (index <= end_index) {
- page = find_get_page(inode->i_mapping, index);
- kmap(page);
- kunmap(page);
- put_page(page);
- index++;
+ heuristic_collect_sample(inode, start, end, ws);
+
+ memset(ws->bucket, 0, sizeof(*ws->bucket)*BUCKET_SIZE);
+
+ for (i = 0; i < ws->sample_size; i++) {
+ byte = ws->sample[i];
+ ws->bucket[byte].count++;
}
__free_workspace(0, ws_list, true);
--
2.14.2
--
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