zio_compress: introduce max size threshold

Now default compression is lz4, which can stop
compression process by itself on incompressible data.
If there are additional size checks -
we will only make our compressratio worse.

New usable compression thresholds are:
- less than BPE_PAYLOAD_SIZE (embedded_data feature);
- at least one saved sector.

Old 12.5% threshold is left to minimize affect
on existing user expectations of CPU utilization.

If data wasn't compressed - it will be saved as
ZIO_COMPRESS_OFF, so if we really need to recompress
data without ashift info and check anything -
we can just compress it with zero threshold.
So, we don't need a new feature flag here!

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Tony Hutter <hutter2@llnl.gov>
Reviewed-by: Alexander Motin <mav@FreeBSD.org>
Signed-off-by: George Melikov <mail@gmelikov.ru>
Closes #9416

include/sys/zio.h

@@ -29,6 +29,7 @@
  * Copyright (c) 2019, Allan Jude
  * Copyright (c) 2019, 2023, 2024, Klara Inc.
  * Copyright (c) 2019-2020, Michael Niewöhner
+ * Copyright (c) 2024 by George Melikov. All rights reserved.
  */
 
 #ifndef _ZIO_H
@@ -603,6 +604,8 @@ extern int zio_alloc_zil(spa_t *spa, objset_t *os, uint64_t txg,
 extern void zio_flush(zio_t *zio, vdev_t *vd);
 extern void zio_shrink(zio_t *zio, uint64_t size);
 
+extern size_t zio_get_compression_max_size(uint64_t gcd_alloc,
+    uint64_t min_alloc, size_t s_len);
 extern int zio_wait(zio_t *zio);
 extern void zio_nowait(zio_t *zio);
 extern void zio_execute(void *zio);

include/sys/zio_compress.h

@@ -25,6 +25,7 @@
  * Copyright (c) 2019, 2024, Klara, Inc.
  * Use is subject to license terms.
  * Copyright (c) 2015, 2016 by Delphix. All rights reserved.
+ * Copyright (c) 2021, 2024 by George Melikov. All rights reserved.
  */
 
 #ifndef _SYS_ZIO_COMPRESS_H
@@ -174,7 +175,7 @@ extern int zfs_lz4_decompress(abd_t *src, abd_t *dst, size_t s_len,
  * Compress and decompress data if necessary.
  */
 extern size_t zio_compress_data(enum zio_compress c, abd_t *src, abd_t **dst,
-    size_t s_len, uint8_t level);
+    size_t s_len, size_t d_len, uint8_t level);
 extern int zio_decompress_data(enum zio_compress c, abd_t *src, abd_t *abd,
     size_t s_len, size_t d_len, uint8_t *level);
 extern int zio_compress_to_feature(enum zio_compress comp);