Make it cleaner

Refactor the logic as a tiny wrapper.

(Also a nit that snuck in on the lz4_zfs.c move somehow.)

Signed-off-by: Rich Ercolani <rincebrain@gmail.com>

include/sys/zstd/zstd.h

@@ -90,6 +90,8 @@ void zstd_fini(void);
 
 size_t zfs_zstd_compress(void *s_start, void *d_start, size_t s_len,
     size_t d_len, int level);
+size_t zfs_zstd_compress_wrap(void *s_start, void *d_start, size_t s_len,
+    size_t d_len, int level);
 int zfs_zstd_get_level(void *s_start, size_t s_len, uint8_t *level);
 int zfs_zstd_decompress_level(void *s_start, void *d_start, size_t s_len,
     size_t d_len, uint8_t *level);

module/zcommon/lz4_zfs.c

@@ -883,4 +883,3 @@ EXPORT_SYMBOL(lz4_compress_zfs);
 EXPORT_SYMBOL(lz4_init);
 EXPORT_SYMBOL(lz4_fini);
 EXPORT_SYMBOL(lz4_decompress_zfs);
-

module/zstd/zfs_zstd.c

@@ -385,11 +385,16 @@ size_t
 zfs_zstd_compress_wrap(void *s_start, void *d_start, size_t s_len, size_t d_len,
     int level)
 {
+	int16_t zstd_level;
+	if (zstd_enum_to_level(level, &zstd_level)) {
+		ZSTDSTAT_BUMP(zstd_stat_com_inval);
+		return (s_len);
+	}
 	/*
 	 * A zstd early abort heuristic.
 	 *
-	 * - Zeroth, if this is <= zstd-3, or < zstd_abort_size (currently 128k),
-	 *   don't try any of this, just go.
+	 * - Zeroth, if this is <= zstd-3, or < zstd_abort_size (currently
+	 *   128k), don't try any of this, just go.
 	 *   (because experimentally that was a reasonable cutoff for a perf win
 	 *   with tiny ratio change)
 	 * - First, we try LZ4 compression, and if it doesn't early abort, we