btrfs: derive maximum output size in the compression implementation

The value of max_out can be calculated from the parameters passed to the
compressors, which is number of pages and the page size, and we don't
have to needlessly pass it around.

Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/compression.c

@@ -932,8 +932,7 @@ int btrfs_compress_pages(int type, struct address_space *mapping,
 			 u64 start, struct page **pages,
 			 unsigned long *out_pages,
 			 unsigned long *total_in,
-			 unsigned long *total_out,
-			 unsigned long max_out)
+			 unsigned long *total_out)
 {
 	struct list_head *workspace;
 	int ret;
@@ -943,8 +942,7 @@ int btrfs_compress_pages(int type, struct address_space *mapping,
 	ret = btrfs_compress_op[type-1]->compress_pages(workspace, mapping,
 						      start, pages,
 						      out_pages,
-						      total_in, total_out,
-						      max_out);
+						      total_in, total_out);
 	free_workspace(type, workspace);
 	return ret;
 }

fs/btrfs/compression.h

@@ -41,8 +41,7 @@ int btrfs_compress_pages(int type, struct address_space *mapping,
 			 u64 start, struct page **pages,
 			 unsigned long *out_pages,
 			 unsigned long *total_in,
-			 unsigned long *total_out,
-			 unsigned long max_out);
+			 unsigned long *total_out);
 int btrfs_decompress(int type, unsigned char *data_in, struct page *dest_page,
 		     unsigned long start_byte, size_t srclen, size_t destlen);
 int btrfs_decompress_buf2page(const char *buf, unsigned long buf_start,
@@ -76,8 +75,7 @@ struct btrfs_compress_op {
 			      struct page **pages,
 			      unsigned long *out_pages,
 			      unsigned long *total_in,
-			      unsigned long *total_out,
-			      unsigned long max_out);
+			      unsigned long *total_out);
 
 	int (*decompress_bio)(struct list_head *workspace,
 				 struct page **pages_in,

fs/btrfs/inode.c

@@ -510,8 +510,7 @@ again:
 					   pages,
 					   &nr_pages,
 					   &total_in,
-					   &total_compressed,
-					   BTRFS_MAX_COMPRESSED);
+					   &total_compressed);
 
 		if (!ret) {
 			unsigned long offset = total_compressed &

fs/btrfs/lzo.c

@@ -90,8 +90,7 @@ static int lzo_compress_pages(struct list_head *ws,
 			      struct page **pages,
 			      unsigned long *out_pages,
 			      unsigned long *total_in,
-			      unsigned long *total_out,
-			      unsigned long max_out)
+			      unsigned long *total_out)
 {
 	struct workspace *workspace = list_entry(ws, struct workspace, list);
 	int ret = 0;
@@ -103,6 +102,7 @@ static int lzo_compress_pages(struct list_head *ws,
 	unsigned long bytes_left;
 	unsigned long len = *total_out;
 	unsigned long nr_dest_pages = *out_pages;
+	const unsigned long max_out = nr_dest_pages * PAGE_SIZE;
 	size_t in_len;
 	size_t out_len;
 	char *buf;

fs/btrfs/zlib.c

@@ -77,8 +77,7 @@ static int zlib_compress_pages(struct list_head *ws,
 			       struct page **pages,
 			       unsigned long *out_pages,
 			       unsigned long *total_in,
-			       unsigned long *total_out,
-			       unsigned long max_out)
+			       unsigned long *total_out)
 {
 	struct workspace *workspace = list_entry(ws, struct workspace, list);
 	int ret;
@@ -90,6 +89,7 @@ static int zlib_compress_pages(struct list_head *ws,
 	unsigned long bytes_left;
 	unsigned long len = *total_out;
 	unsigned long nr_dest_pages = *out_pages;
+	const unsigned long max_out = nr_dest_pages * PAGE_SIZE;
 
 	*out_pages = 0;
 	*total_out = 0;