From 38c31464089f639630b7c28ce933a4d60e135a02 Mon Sep 17 00:00:00 2001 From: David Sterba Date: Tue, 14 Feb 2017 19:04:07 +0100 Subject: [PATCH] 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: David Sterba --- fs/btrfs/compression.c | 24 +++++++++++------------- fs/btrfs/compression.h | 5 ++--- fs/btrfs/inode.c | 2 +- fs/btrfs/lzo.c | 4 ++-- fs/btrfs/zlib.c | 3 ++- 5 files changed, 18 insertions(+), 20 deletions(-) diff --git a/fs/btrfs/compression.c b/fs/btrfs/compression.c index d426e4a10b2b..7e214fd254e4 100644 --- a/fs/btrfs/compression.c +++ b/fs/btrfs/compression.c @@ -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); diff --git a/fs/btrfs/compression.h b/fs/btrfs/compression.h index 1c700bb20b52..725d1e0bd25d 100644 --- a/fs/btrfs/compression.h +++ b/fs/btrfs/compression.h @@ -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, diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c index 596e5cb4bfa2..8b9eac33d431 100644 --- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -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, diff --git a/fs/btrfs/lzo.c b/fs/btrfs/lzo.c index e074b85aa054..489f78c4e5ec 100644 --- a/fs/btrfs/lzo.c +++ b/fs/btrfs/lzo.c @@ -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; diff --git a/fs/btrfs/zlib.c b/fs/btrfs/zlib.c index da497f184ff4..42d76b7824c3 100644 --- a/fs/btrfs/zlib.c +++ b/fs/btrfs/zlib.c @@ -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; -- 2.20.1