[3/7] btrfs: zstd: move zstd_parameters to the workspace

Commit Message

David Sterba Feb. 12, 2025, 8:22 p.m. UTC

Reduce stack consumption of zstd_compress_folios() by 40 bytes
(10*sizeof(int)) as we can store struct zstd_parameters in the workspace
that is reused for each call.

typedef struct {
	ZSTD_compressionParameters cParams;
	ZSTD_frameParameters fParams;
} ZSTD_parameters;

typedef struct {
    unsigned windowLog;
    unsigned chainLog;
    unsigned hashLog;
    unsigned searchLog;
    unsigned minMatch;
    unsigned targetLength;
    ZSTD_strategy strategy;
} ZSTD_compressionParameters;

typedef struct {
    int contentSizeFlag;
    int checksumFlag;
    int noDictIDFlag;
} ZSTD_frameParameters;

Signed-off-by: David Sterba <[e-mail]>
---
 fs/btrfs/zstd.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

Patch

diff --git a/fs/btrfs/zstd.c b/fs/btrfs/zstd.c
index a7bfbf8bea7d..5419c47b854f 100644
--- a/fs/btrfs/zstd.c
+++ b/fs/btrfs/zstd.c
@@ -53,6 +53,7 @@  struct workspace {
 	struct list_head lru_list;
 	zstd_in_buffer in_buf;
 	zstd_out_buffer out_buf;
+	zstd_parameters params;
 };
 
 /*
@@ -402,15 +403,14 @@  int zstd_compress_folios(struct list_head *ws, struct address_space *mapping,
 	unsigned long max_out = nr_dest_folios * PAGE_SIZE;
 	unsigned int pg_off;
 	unsigned int cur_len;
-	zstd_parameters params = zstd_get_btrfs_parameters(workspace->req_level,
-							   len);
 
+	workspace->params = zstd_get_btrfs_parameters(workspace->req_level, len);
 	*out_folios = 0;
 	*total_out = 0;
 	*total_in = 0;
 
 	/* Initialize the stream */
-	stream = zstd_init_cstream(&params, len, workspace->mem,
+	stream = zstd_init_cstream(&workspace->params, len, workspace->mem,
 			workspace->size);
 	if (unlikely(!stream)) {
 		struct btrfs_inode *inode = BTRFS_I(mapping->host);