btrfs: compression: replace set_level callbacks by a common helper

The set_level callbacks do not do anything special and can be replaced
by a helper that uses the levels defined in the tables.

Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/compression.c

@@ -1039,7 +1039,7 @@ int btrfs_compress_pages(unsigned int type_level, struct address_space *mapping,
 	struct list_head *workspace;
 	int ret;
 
-	level = btrfs_compress_op[type]->set_level(level);
+	level = btrfs_compress_set_level(type, level);
 	workspace = get_workspace(type, level);
 	ret = btrfs_compress_op[type]->compress_pages(workspace, mapping,
 						      start, pages,
@@ -1611,7 +1611,23 @@ unsigned int btrfs_compress_str2level(unsigned int type, const char *str)
 			level = 0;
 	}
 
-	level = btrfs_compress_op[type]->set_level(level);
+	level = btrfs_compress_set_level(type, level);
+
+	return level;
+}
+
+/*
+ * Adjust @level according to the limits of the compression algorithm or
+ * fallback to default
+ */
+unsigned int btrfs_compress_set_level(int type, unsigned level)
+{
+	const struct btrfs_compress_op *ops = btrfs_compress_op[type];
+
+	if (level == 0)
+		level = ops->default_level;
+	else
+		level = min(level, ops->max_level);
 
 	return level;
 }

fs/btrfs/compression.h

@@ -156,13 +156,6 @@ struct btrfs_compress_op {
 			  unsigned long start_byte,
 			  size_t srclen, size_t destlen);
 
-	/*
-	 * This bounds the level set by the user to be within range of a
-	 * particular compression type.  It returns the level that will be used
-	 * if the level is out of bounds or the default if 0 is passed in.
-	 */
-	unsigned int (*set_level)(unsigned int level);
-
 	/* Maximum level supported by the compression algorithm */
 	unsigned int max_level;
 	unsigned int default_level;
@@ -179,6 +172,8 @@ extern const struct btrfs_compress_op btrfs_zstd_compress;
 const char* btrfs_compress_type2str(enum btrfs_compression_type type);
 bool btrfs_compress_is_valid_type(const char *str, size_t len);
 
+unsigned int btrfs_compress_set_level(int type, unsigned level);
+
 int btrfs_compress_heuristic(struct inode *inode, u64 start, u64 end);
 
 #endif

fs/btrfs/lzo.c

@@ -507,11 +507,6 @@ static int lzo_decompress(struct list_head *ws, unsigned char *data_in,
 	return ret;
 }
 
-static unsigned int lzo_set_level(unsigned int level)
-{
-	return 0;
-}
-
 const struct btrfs_compress_op btrfs_lzo_compress = {
 	.init_workspace_manager	= lzo_init_workspace_manager,
 	.cleanup_workspace_manager = lzo_cleanup_workspace_manager,
@@ -522,7 +517,6 @@ const struct btrfs_compress_op btrfs_lzo_compress = {
 	.compress_pages		= lzo_compress_pages,
 	.decompress_bio		= lzo_decompress_bio,
 	.decompress		= lzo_decompress,
-	.set_level		= lzo_set_level,
 	.max_level		= 1,
 	.default_level		= 1,
 };

fs/btrfs/zlib.c

@@ -418,14 +418,6 @@ static int zlib_decompress(struct list_head *ws, unsigned char *data_in,
 	return ret;
 }
 
-static unsigned int zlib_set_level(unsigned int level)
-{
-	if (!level)
-		return BTRFS_ZLIB_DEFAULT_LEVEL;
-
-	return min_t(unsigned int, level, 9);
-}
-
 const struct btrfs_compress_op btrfs_zlib_compress = {
 	.init_workspace_manager	= zlib_init_workspace_manager,
 	.cleanup_workspace_manager = zlib_cleanup_workspace_manager,
@@ -436,7 +428,6 @@ const struct btrfs_compress_op btrfs_zlib_compress = {
 	.compress_pages		= zlib_compress_pages,
 	.decompress_bio		= zlib_decompress_bio,
 	.decompress		= zlib_decompress,
-	.set_level              = zlib_set_level,
 	.max_level		= 9,
 	.default_level		= BTRFS_ZLIB_DEFAULT_LEVEL,
 };

fs/btrfs/zstd.c

@@ -710,14 +710,6 @@ static int zstd_decompress(struct list_head *ws, unsigned char *data_in,
 	return ret;
 }
 
-static unsigned int zstd_set_level(unsigned int level)
-{
-	if (!level)
-		return ZSTD_BTRFS_DEFAULT_LEVEL;
-
-	return min_t(unsigned int, level, ZSTD_BTRFS_MAX_LEVEL);
-}
-
 const struct btrfs_compress_op btrfs_zstd_compress = {
 	.init_workspace_manager = zstd_init_workspace_manager,
 	.cleanup_workspace_manager = zstd_cleanup_workspace_manager,
@@ -728,7 +720,6 @@ const struct btrfs_compress_op btrfs_zstd_compress = {
 	.compress_pages = zstd_compress_pages,
 	.decompress_bio = zstd_decompress_bio,
 	.decompress = zstd_decompress,
-	.set_level = zstd_set_level,
 	.max_level	= ZSTD_BTRFS_MAX_LEVEL,
 	.default_level	= ZSTD_BTRFS_DEFAULT_LEVEL,
 };