Commit 38c31464 authored by David Sterba's avatar David Sterba
Browse files

btrfs: merge length input and output parameter in compress_pages 



The length parameter is basically duplicated for input and output in the
top level caller of the compress_pages chain. We can simply use one
variable for that and reduce stack consumption. The compression
implementation will sink the parameter to a local variable so everything
works as before.

Signed-off-by: default avatarDavid Sterba <dsterba@suse.com>
parent 52f75f4f

fs/btrfs/compression.c

+11 −13
Original line number Diff line number Diff line
@@ -911,27 +911,25 @@ static void free_workspaces(void) 
}



/*

 * given an address space and start/len, compress the bytes.

 * Given an address space and start and length, compress the bytes into @pages

 * that are allocated on demand.

 *

 * pages are allocated to hold the compressed result and stored

 * in 'pages'

 * @out_pages is used to return the number of pages allocated.  There

 * may be pages allocated even if we return an error.

 *

 * out_pages is used to return the number of pages allocated.  There

 * may be pages allocated even if we return an error

 *

 * total_in is used to return the number of bytes actually read.  It

 * may be smaller then len if we had to exit early because we

 * @total_in is used to return the number of bytes actually read.  It

 * may be smaller than the input length if we had to exit early because we

 * ran out of room in the pages array or because we cross the

 * max_out threshold.

 *

 * total_out is used to return the total number of compressed bytes

 * @total_out is an in/out parameter, must be set to the input length and will

 * be also used to return the total number of compressed bytes

 *

 * max_out tells us the max number of bytes that we're allowed to

 * @max_out tells us the max number of bytes that we're allowed to

 * stuff into pages

 */

int btrfs_compress_pages(int type, struct address_space *mapping,

			 u64 start, unsigned long len,

			 struct page **pages,

			 u64 start, struct page **pages,

			 unsigned long nr_dest_pages,

			 unsigned long *out_pages,

			 unsigned long *total_in,
@@ -944,7 +942,7 @@ int btrfs_compress_pages(int type, struct address_space *mapping, 
	workspace = find_workspace(type);



	ret = btrfs_compress_op[type-1]->compress_pages(workspace, mapping,

						      start, len, pages,

						      start, pages,

						      nr_dest_pages, out_pages,

						      total_in, total_out,

						      max_out);

fs/btrfs/compression.h

+2 −3
Original line number Diff line number Diff line
@@ -23,8 +23,7 @@ void btrfs_init_compress(void); 
void btrfs_exit_compress(void);



int btrfs_compress_pages(int type, struct address_space *mapping,

			 u64 start, unsigned long len,

			 struct page **pages,

			 u64 start, struct page **pages,

			 unsigned long nr_dest_pages,

			 unsigned long *out_pages,

			 unsigned long *total_in,
@@ -59,7 +58,7 @@ struct btrfs_compress_op { 


	int (*compress_pages)(struct list_head *workspace,

			      struct address_space *mapping,

			      u64 start, unsigned long len,

			      u64 start,

			      struct page **pages,

			      unsigned long nr_dest_pages,

			      unsigned long *out_pages,

fs/btrfs/inode.c

+1 −1
Original line number Diff line number Diff line
@@ -517,7 +517,7 @@ again: 
		redirty = 1;

		ret = btrfs_compress_pages(compress_type,

					   inode->i_mapping, start,

					   total_compressed, pages,

					   pages,

					   nr_pages, &nr_pages_ret,

					   &total_in,

					   &total_compressed,

fs/btrfs/lzo.c

+2 −2
Original line number Diff line number Diff line
@@ -86,7 +86,7 @@ static inline size_t read_compress_length(const char *buf) 


static int lzo_compress_pages(struct list_head *ws,

			      struct address_space *mapping,

			      u64 start, unsigned long len,

			      u64 start,

			      struct page **pages,

			      unsigned long nr_dest_pages,

			      unsigned long *out_pages,
@@ -102,7 +102,7 @@ static int lzo_compress_pages(struct list_head *ws, 
	struct page *in_page = NULL;

	struct page *out_page = NULL;

	unsigned long bytes_left;



	unsigned long len = *total_out;

	size_t in_len;

	size_t out_len;

	char *buf;

fs/btrfs/zlib.c

+2 −1
Original line number Diff line number Diff line
@@ -73,7 +73,7 @@ fail: 


static int zlib_compress_pages(struct list_head *ws,

			       struct address_space *mapping,

			       u64 start, unsigned long len,

			       u64 start,

			       struct page **pages,

			       unsigned long nr_dest_pages,

			       unsigned long *out_pages,
@@ -89,6 +89,7 @@ static int zlib_compress_pages(struct list_head *ws, 
	struct page *in_page = NULL;

	struct page *out_page = NULL;

	unsigned long bytes_left;

	unsigned long len = *total_out;



	*out_pages = 0;

	*total_out = 0;

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