On 2021/6/29 下午8:23, Qu Wenruo wrote:

Here missing a put_page() and will cause memory leakage.

Already fixed in my github compression branch.

Thanks,
Qu

+			/* Let next iteration to grab a page */
+			cur_page = NULL;
+		}
+	}
+
+	/*
+	 * Check if we can fit the next segment header into the remaining space
+	 * of the sector.
+	 */
+	sector_bytes_left = round_up(*cur_out, sectorsize) - *cur_out;
+	if (sector_bytes_left >= LZO_LEN)
+		return 0;
+
+	/* The remaining size is not enough, pad it with zeros */
+	memset(page_address(cur_page) + offset_in_page(*cur_out), 0,
+	       sector_bytes_left);
+	*cur_out += sector_bytes_left;
+	return 0;
+}
+
  int lzo_compress_pages(struct list_head *ws, struct address_space *mapping,
  		u64 start, struct page **pages, unsigned long *out_pages,
  		unsigned long *total_in, unsigned long *total_out)
  {
  	struct workspace *workspace = list_entry(ws, struct workspace, list);
+	const u32 sectorsize = btrfs_sb(mapping->host->i_sb)->sectorsize;
+	struct page *page_in = NULL;
  	int ret = 0;
-	char *data_in;
-	char *cpage_out, *sizes_ptr;
-	int nr_pages = 0;
-	struct page *in_page = NULL;
-	struct page *out_page = NULL;
-	unsigned long bytes_left;
-	unsigned long len = *total_out;
-	unsigned long nr_dest_pages = *out_pages;
-	const unsigned long max_out = nr_dest_pages * PAGE_SIZE;
-	size_t in_len;
-	size_t out_len;
-	char *buf;
-	unsigned long tot_in = 0;
-	unsigned long tot_out = 0;
-	unsigned long pg_bytes_left;
-	unsigned long out_offset;
-	unsigned long bytes;
+	u64 cur_in = start;	/* Points to the file offset of input data */
+	u32 cur_out = 0;	/* Points to the current output byte */
+	u32 len = *total_out;

  	*out_pages = 0;
  	*total_out = 0;
  	*total_in = 0;

-	in_page = find_get_page(mapping, start >> PAGE_SHIFT);
-	data_in = kmap(in_page);
-
  	/*
-	 * store the size of all chunks of compressed data in
-	 * the first 4 bytes
+	 * Skip the header for now, we will later come back and write the total
+	 * compressed size
  	 */
-	out_page = alloc_page(GFP_NOFS | __GFP_HIGHMEM);
-	if (out_page == NULL) {
-		ret = -ENOMEM;
-		goto out;
-	}
-	cpage_out = kmap(out_page);
-	out_offset = LZO_LEN;
-	tot_out = LZO_LEN;
-	pages[0] = out_page;
-	nr_pages = 1;
-	pg_bytes_left = PAGE_SIZE - LZO_LEN;
-
-	/* compress at most one page of data each time */
-	in_len = min(len, PAGE_SIZE);
-	while (tot_in < len) {
-		ret = lzo1x_1_compress(data_in, in_len, workspace->cbuf,
-				       &out_len, workspace->mem);
-		if (ret != LZO_E_OK) {
-			pr_debug("BTRFS: lzo in loop returned %d\n",
-			       ret);
+	cur_out += LZO_LEN;
+	while (cur_in < start + len) {
+		u32 sector_off = (cur_in - start) % sectorsize;
+		u32 in_len;
+		size_t out_len;
+
+		/* Get the input page first */
+		if (!page_in) {
+			page_in = find_get_page(mapping, cur_in >> PAGE_SHIFT);
+			ASSERT(page_in);
+		}
+
+		/* Compress at most one sector of data each time */
+		in_len = min_t(u32, start + len - cur_in,
+			       sectorsize - sector_off);
+		ASSERT(in_len);
+		ret = lzo1x_1_compress(page_address(page_in) +
+				       offset_in_page(cur_in), in_len,
+				       workspace->cbuf, &out_len,
+				       workspace->mem);
+		if (ret < 0) {
+			pr_debug("BTRFS: lzo in loop returned %d\n", ret);
  			ret = -EIO;
  			goto out;
  		}

-		/* store the size of this chunk of compressed data */
-		write_compress_length(cpage_out + out_offset, out_len);
-		tot_out += LZO_LEN;
-		out_offset += LZO_LEN;
-		pg_bytes_left -= LZO_LEN;
-
-		tot_in += in_len;
-		tot_out += out_len;
-
-		/* copy bytes from the working buffer into the pages */
-		buf = workspace->cbuf;
-		while (out_len) {
-			bytes = min_t(unsigned long, pg_bytes_left, out_len);
-
-			memcpy(cpage_out + out_offset, buf, bytes);
-
-			out_len -= bytes;
-			pg_bytes_left -= bytes;
-			buf += bytes;
-			out_offset += bytes;
-
-			/*
-			 * we need another page for writing out.
-			 *
-			 * Note if there's less than 4 bytes left, we just
-			 * skip to a new page.
-			 */
-			if ((out_len == 0 && pg_bytes_left < LZO_LEN) ||
-			    pg_bytes_left == 0) {
-				if (pg_bytes_left) {
-					memset(cpage_out + out_offset, 0,
-					       pg_bytes_left);
-					tot_out += pg_bytes_left;
-				}
-
-				/* we're done, don't allocate new page */
-				if (out_len == 0 && tot_in >= len)
-					break;
-
-				kunmap(out_page);
-				if (nr_pages == nr_dest_pages) {
-					out_page = NULL;
-					ret = -E2BIG;
-					goto out;
-				}
-
-				out_page = alloc_page(GFP_NOFS | __GFP_HIGHMEM);
-				if (out_page == NULL) {
-					ret = -ENOMEM;
-					goto out;
-				}
-				cpage_out = kmap(out_page);
-				pages[nr_pages++] = out_page;
+		ret = copy_compressed_data_to_page(workspace->cbuf, out_len,
+						   pages, &cur_out, sectorsize);
+		if (ret < 0)
+			goto out;

-				pg_bytes_left = PAGE_SIZE;
-				out_offset = 0;
-			}
-		}
+		cur_in += in_len;

-		/* we're making it bigger, give up */
-		if (tot_in > 8192 && tot_in < tot_out) {
+		/*
+		 * Check if we're making it bigger after two sectors.
+		 * And if we're making it bigger, give up.
+		 */
+		if (cur_in - start > sectorsize * 2 &&
+		    cur_in - start < cur_out) {
  			ret = -E2BIG;
  			goto out;
  		}

-		/* we're all done */
-		if (tot_in >= len)
-			break;
-
-		if (tot_out > max_out)
-			break;
-
-		bytes_left = len - tot_in;
-		kunmap(in_page);
-		put_page(in_page);
-
-		start += PAGE_SIZE;
-		in_page = find_get_page(mapping, start >> PAGE_SHIFT);
-		data_in = kmap(in_page);
-		in_len = min(bytes_left, PAGE_SIZE);
-	}
-
-	if (tot_out >= tot_in) {
-		ret = -E2BIG;
-		goto out;
+		/* Check if we have reached page boundary */
+		if (IS_ALIGNED(cur_in, PAGE_SIZE))
+			page_in = NULL;
  	}

-	/* store the size of all chunks of compressed data */
-	sizes_ptr = kmap_local_page(pages[0]);
-	write_compress_length(sizes_ptr, tot_out);
-	kunmap_local(sizes_ptr);
+	/* Store the size of all chunks of compressed data */
+	write_compress_length(page_address(pages[0]), cur_out);

  	ret = 0;
-	*total_out = tot_out;
-	*total_in = tot_in;
+	*total_out = cur_out;
+	*total_in = cur_in - start;
  out:
-	*out_pages = nr_pages;
-	if (out_page)
-		kunmap(out_page);
-
-	if (in_page) {
-		kunmap(in_page);
-		put_page(in_page);
-	}
-
+	*out_pages = DIV_ROUND_UP(cur_out, PAGE_SIZE);
  	return ret;
  }