zio_compress_data: add 'check_ratio' arg

If data was compressed and passed ratio
checks before - we can skip these checks
for reproducible results.

Signed-off-by: George Melikov <[email protected]>

Author: gmelikov

include/sys/zio_compress.h

@@ -110,7 +110,7 @@ extern int lz4_decompress_zfs(void *src, void *dst, size_t s_len, size_t d_len,
  * Compress and decompress data if necessary.
  */
 extern size_t zio_compress_data(enum zio_compress c, abd_t *src, void *dst,
-    size_t s_len);
+    size_t s_len, boolean_t check_ratio);
 extern int zio_decompress_data(enum zio_compress c, abd_t *src, void *dst,
     size_t s_len, size_t d_len);
 extern int zio_decompress_data_buf(enum zio_compress c, void *src, void *dst,

module/zfs/arc.c

@@ -1629,7 +1629,7 @@ arc_hdr_authenticate(arc_buf_hdr_t *hdr, spa_t *spa, uint64_t dsobj)
 		abd_take_ownership_of_buf(abd, B_TRUE);
 
 		csize = zio_compress_data(HDR_GET_COMPRESS(hdr),
-		    hdr->b_l1hdr.b_pabd, tmpbuf, lsize);
+		    hdr->b_l1hdr.b_pabd, tmpbuf, lsize, B_FALSE);
 		ASSERT3U(csize, <=, psize);
 		abd_zero_off(abd, csize, psize - csize);
 	}
@@ -8113,7 +8113,8 @@ l2arc_apply_transforms(spa_t *spa, arc_buf_hdr_t *hdr, uint64_t asize,
 		cabd = abd_alloc_for_io(asize, ismd);
 		tmp = abd_borrow_buf(cabd, asize);
 
-		psize = zio_compress_data(compress, to_write, tmp, size);
+		psize = zio_compress_data(compress, to_write, tmp, size,
+		    B_FALSE);
 		ASSERT3U(psize, <=, HDR_GET_PSIZE(hdr));
 		if (psize < asize)
 			bzero((char *)tmp + psize, asize - psize);

module/zfs/zio.c

@@ -1607,7 +1607,8 @@ zio_write_compress(zio_t *zio)
 	if (compress != ZIO_COMPRESS_OFF &&
 	    !(zio->io_flags & ZIO_FLAG_RAW_COMPRESS)) {
 		void *cbuf = zio_buf_alloc(lsize);
-		psize = zio_compress_data(compress, zio->io_abd, cbuf, lsize);
+		psize = zio_compress_data(compress, zio->io_abd, cbuf, lsize,
+		    B_TRUE);
 		if (psize == 0 || psize == lsize) {
 			compress = ZIO_COMPRESS_OFF;
 			zio_buf_free(cbuf, lsize);
@@ -1670,7 +1671,7 @@ zio_write_compress(zio_t *zio)
 		 * to a hole.
 		 */
 		psize = zio_compress_data(ZIO_COMPRESS_EMPTY,
-		    zio->io_abd, NULL, lsize);
+		    zio->io_abd, NULL, lsize, B_FALSE);
 		if (psize == 0)
 			compress = ZIO_COMPRESS_OFF;
 	} else {

module/zfs/zio_compress.c

@@ -101,7 +101,8 @@ zio_compress_zeroed_cb(void *data, size_t len, void *private)
 }
 
 size_t
-zio_compress_data(enum zio_compress c, abd_t *src, void *dst, size_t s_len)
+zio_compress_data(enum zio_compress c, abd_t *src, void *dst, size_t s_len,
+    boolean_t check_ratio)
 {
 	size_t c_len, d_len;
 	zio_compress_info_t *ci = &zio_compress_table[c];
@@ -119,12 +120,23 @@ zio_compress_data(enum zio_compress c, abd_t *src, void *dst, size_t s_len)
 	if (c == ZIO_COMPRESS_EMPTY)
 		return (s_len);
 
-	/* Data is already less or equal to compress threshold */
-	if (s_len <= zfs_compress_threshold_bytes)
-		return (s_len);
-
-	/* Write compressed only if there is at least one sector compressed */
-	d_len = s_len - MIN(s_len, zfs_compress_threshold_bytes);
+	/*
+	 * If data was compressed and passed ratio checks before -
+	 * we can skip these checks for reproducible results.
+	 */
+	if (check_ratio) {
+		/* Data is already less or equal to compress threshold */
+		if (s_len <= zfs_compress_threshold_bytes)
+			return (s_len);
+
+		/*
+		 * Write compressed only if there is at least
+		 * one sector compressed
+		 */
+		d_len = s_len - MIN(s_len, zfs_compress_threshold_bytes);
+	} else {
+		d_len = s_len;
+	}
 
 	/* No compression algorithms can read from ABDs directly */
 	void *tmp = abd_borrow_buf_copy(src, s_len);