btrfs: compression: attach workspace manager to the ops

There's a lot of indirection when the generic code calls into
algo-specific callbacks to reach the private workspace manager structure
and back to the generic code.

To simplify that, export the workspace manager for heuristic, LZO and
ZLIB, while ZSTD is going to use it's own manager.
Reviewed-by: NJohannes Thumshirn <jthumshirn@suse.de>
Reviewed-by: NNikolay Borisov <nborisov@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

fs/btrfs/compression.c

@@ -920,6 +920,7 @@ static struct list_head *alloc_heuristic_ws(unsigned int level)
 }
 
 const struct btrfs_compress_op btrfs_heuristic_compress = {
+	.workspace_manager = &heuristic_wsm,
 	.init_workspace_manager = heuristic_init_workspace_manager,
 	.cleanup_workspace_manager = heuristic_cleanup_workspace_manager,
 	.get_workspace = heuristic_get_workspace,

fs/btrfs/compression.h

@@ -140,6 +140,7 @@ struct btrfs_compress_op {
 
 	void (*free_workspace)(struct list_head *workspace);
 
+	struct workspace_manager *workspace_manager;
 	/* Maximum level supported by the compression algorithm */
 	unsigned int max_level;
 	unsigned int default_level;

fs/btrfs/lzo.c

@@ -503,6 +503,7 @@ int lzo_decompress(struct list_head *ws, unsigned char *data_in,
 }
 
 const struct btrfs_compress_op btrfs_lzo_compress = {
+	.workspace_manager	= &wsm,
 	.init_workspace_manager	= lzo_init_workspace_manager,
 	.cleanup_workspace_manager = lzo_cleanup_workspace_manager,
 	.get_workspace		= lzo_get_workspace,

fs/btrfs/zlib.c

@@ -414,6 +414,7 @@ int zlib_decompress(struct list_head *ws, unsigned char *data_in,
 }
 
 const struct btrfs_compress_op btrfs_zlib_compress = {
+	.workspace_manager	= &wsm,
 	.init_workspace_manager	= zlib_init_workspace_manager,
 	.cleanup_workspace_manager = zlib_cleanup_workspace_manager,
 	.get_workspace		= zlib_get_workspace,

fs/btrfs/zstd.c

@@ -707,6 +707,8 @@ int zstd_decompress(struct list_head *ws, unsigned char *data_in,
 }
 
 const struct btrfs_compress_op btrfs_zstd_compress = {
+	/* ZSTD uses own workspace manager */
+	.workspace_manager = NULL,
 	.init_workspace_manager = zstd_init_workspace_manager,
 	.cleanup_workspace_manager = zstd_cleanup_workspace_manager,
 	.get_workspace = zstd_get_workspace,