Re: [PATCH 3/3] btrfs: switch types to int when counting eb pages

[Nikolay Borisov <nborisov@suse.com>]

On 24.04.2018 02:03, David Sterba wrote:
> The loops iterating eb pages use unsigned long, that's an overkill as
> we know that there are at most 16 pages (64k / 4k), and 4 by default
> (with nodesize 16k).
> 
> Signed-off-by: David Sterba <dsterba@suse.com>
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
> ---
>  fs/btrfs/extent_io.c | 44 ++++++++++++++++++++++----------------------
>  fs/btrfs/extent_io.h |  2 +-
>  2 files changed, 23 insertions(+), 23 deletions(-)
> 
> diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
> index 0cc5d6ae1876..5bdfdb9c8777 100644
> --- a/fs/btrfs/extent_io.c
> +++ b/fs/btrfs/extent_io.c
> @@ -2062,7 +2062,7 @@ int repair_eb_io_failure(struct btrfs_fs_info *fs_info,
>  			 struct extent_buffer *eb, int mirror_num)
>  {
>  	u64 start = eb->start;
> -	unsigned long i, num_pages = num_extent_pages(eb);
> +	int i, num_pages = num_extent_pages(eb);
>  	int ret = 0;
>  
>  	if (sb_rdonly(fs_info->sb))
> @@ -3541,7 +3541,7 @@ lock_extent_buffer_for_io(struct extent_buffer *eb,
>  			  struct btrfs_fs_info *fs_info,
>  			  struct extent_page_data *epd)
>  {
> -	unsigned long i, num_pages;
> +	int i, num_pages;
>  	int flush = 0;
>  	int ret = 0;
>  
> @@ -3715,7 +3715,7 @@ static noinline_for_stack int write_one_eb(struct extent_buffer *eb,
>  	struct extent_io_tree *tree = &BTRFS_I(fs_info->btree_inode)->io_tree;
>  	u64 offset = eb->start;
>  	u32 nritems;
> -	unsigned long i, num_pages;
> +	int i, num_pages;
>  	unsigned long start, end;
>  	unsigned int write_flags = wbc_to_write_flags(wbc) | REQ_META;
>  	int ret = 0;
> @@ -4648,7 +4648,7 @@ int extent_buffer_under_io(struct extent_buffer *eb)
>   */
>  static void btrfs_release_extent_buffer_page(struct extent_buffer *eb)
>  {
> -	unsigned long index;
> +	int index;
>  	struct page *page;
>  	int mapped = !test_bit(EXTENT_BUFFER_DUMMY, &eb->bflags);
>  
> @@ -4744,10 +4744,10 @@ __alloc_extent_buffer(struct btrfs_fs_info *fs_info, u64 start,
>  
>  struct extent_buffer *btrfs_clone_extent_buffer(struct extent_buffer *src)
>  {
> -	unsigned long i;
> +	int i;
>  	struct page *p;
>  	struct extent_buffer *new;
> -	unsigned long num_pages = num_extent_pages(src);
> +	int num_pages = num_extent_pages(src);
>  
>  	new = __alloc_extent_buffer(src->fs_info, src->start, src->len);
>  	if (new == NULL)
> @@ -4776,8 +4776,8 @@ struct extent_buffer *__alloc_dummy_extent_buffer(struct btrfs_fs_info *fs_info,
>  						  u64 start, unsigned long len)
>  {
>  	struct extent_buffer *eb;
> -	unsigned long num_pages;
> -	unsigned long i;
> +	int num_pages;
> +	int i;
>  
>  	eb = __alloc_extent_buffer(fs_info, start, len);
>  	if (!eb)
> @@ -4843,7 +4843,7 @@ static void check_buffer_tree_ref(struct extent_buffer *eb)
>  static void mark_extent_buffer_accessed(struct extent_buffer *eb,
>  		struct page *accessed)
>  {
> -	unsigned long num_pages, i;
> +	int num_pages, i;
>  
>  	check_buffer_tree_ref(eb);
>  
> @@ -4944,8 +4944,8 @@ struct extent_buffer *alloc_extent_buffer(struct btrfs_fs_info *fs_info,
>  					  u64 start)
>  {
>  	unsigned long len = fs_info->nodesize;
> -	unsigned long num_pages;
> -	unsigned long i;
> +	int num_pages;
> +	int i;
>  	unsigned long index = start >> PAGE_SHIFT;
>  	struct extent_buffer *eb;
>  	struct extent_buffer *exists = NULL;
> @@ -5160,8 +5160,8 @@ void free_extent_buffer_stale(struct extent_buffer *eb)
>  
>  void clear_extent_buffer_dirty(struct extent_buffer *eb)
>  {
> -	unsigned long i;
> -	unsigned long num_pages;
> +	int i;
> +	int num_pages;
>  	struct page *page;
>  
>  	num_pages = num_extent_pages(eb);
> @@ -5190,8 +5190,8 @@ void clear_extent_buffer_dirty(struct extent_buffer *eb)
>  
>  int set_extent_buffer_dirty(struct extent_buffer *eb)
>  {
> -	unsigned long i;
> -	unsigned long num_pages;
> +	int i;
> +	int num_pages;
>  	int was_dirty = 0;
>  
>  	check_buffer_tree_ref(eb);
> @@ -5209,9 +5209,9 @@ int set_extent_buffer_dirty(struct extent_buffer *eb)
>  
>  void clear_extent_buffer_uptodate(struct extent_buffer *eb)
>  {
> -	unsigned long i;
> +	int i;
>  	struct page *page;
> -	unsigned long num_pages;
> +	int num_pages;
>  
>  	clear_bit(EXTENT_BUFFER_UPTODATE, &eb->bflags);
>  	num_pages = num_extent_pages(eb);
> @@ -5224,9 +5224,9 @@ void clear_extent_buffer_uptodate(struct extent_buffer *eb)
>  
>  void set_extent_buffer_uptodate(struct extent_buffer *eb)
>  {
> -	unsigned long i;
> +	int i;
>  	struct page *page;
> -	unsigned long num_pages;
> +	int num_pages;
>  
>  	set_bit(EXTENT_BUFFER_UPTODATE, &eb->bflags);
>  	num_pages = num_extent_pages(eb);
> @@ -5239,13 +5239,13 @@ void set_extent_buffer_uptodate(struct extent_buffer *eb)
>  int read_extent_buffer_pages(struct extent_io_tree *tree,
>  			     struct extent_buffer *eb, int wait, int mirror_num)
>  {
> -	unsigned long i;
> +	int i;
>  	struct page *page;
>  	int err;
>  	int ret = 0;
>  	int locked_pages = 0;
>  	int all_uptodate = 1;
> -	unsigned long num_pages;
> +	int num_pages;
>  	unsigned long num_reads = 0;
>  	struct bio *bio = NULL;
>  	unsigned long bio_flags = 0;
> @@ -5577,7 +5577,7 @@ void copy_extent_buffer_full(struct extent_buffer *dst,
>  			     struct extent_buffer *src)
>  {
>  	int i;
> -	unsigned num_pages;
> +	int num_pages;
>  
>  	ASSERT(dst->len == src->len);
>  
> diff --git a/fs/btrfs/extent_io.h b/fs/btrfs/extent_io.h
> index d08abc9d385e..3248553a3aa2 100644
> --- a/fs/btrfs/extent_io.h
> +++ b/fs/btrfs/extent_io.h
> @@ -452,7 +452,7 @@ int read_extent_buffer_pages(struct extent_io_tree *tree,
>  			     int mirror_num);
>  void wait_on_extent_buffer_writeback(struct extent_buffer *eb);
>  
> -static inline unsigned long num_extent_pages(const struct extent_buffer *eb)
> +static inline int num_extent_pages(const struct extent_buffer *eb)
>  {
>  	return eb->len >> PAGE_SHIFT;
>  }
>