btrfs: preset set/get token with first page and drop condition (870b388d) · Commits · 戴 / test

All the set/get helpers first check if the token contains a cached address. After first use the address is always valid, but the extra check is done for each call. The token initialization can optimistically set it to the first extent buffer page, that we know always exists. Then the condition in all btrfs_token_*/btrfs_set_token_* can be simplified by removing the address check from the condition, but for development the assertion still makes sure it's valid. Reviewed-by:

Johannes Thumshirn <johannes.thumshirn@wdc.com> Signed-off-by:

David Sterba <dsterba@suse.com>

fs/btrfs/ctree.h

+2 −1

Original line number	Diff line number	Diff line
		@@ -1352,7 +1352,8 @@ static inline void btrfs_init_map_token(struct btrfs_map_token *token,
		struct extent_buffer *eb)
		{
		token->eb = eb;
		token->kaddr = NULL;
		token->kaddr = page_address(eb->pages[0]);
		token->offset = 0;
		}

		/* some macros to generate set/get functions for the struct fields. This

fs/btrfs/struct-funcs.c

+4 −4

Original line number	Diff line number	Diff line
		@@ -52,8 +52,8 @@ u##bits btrfs_get_token_##bits(struct btrfs_map_token *token, \
		u##bits res; \
		\
		ASSERT(token); \
		\
		if (token->kaddr && token->offset <= offset && \
		ASSERT(token->kaddr); \
		if (token->offset <= offset && \
		(token->offset + PAGE_SIZE >= offset + size)) { \
		kaddr = token->kaddr; \
		p = kaddr + part_offset - token->offset; \
		@@ -113,8 +113,8 @@ void btrfs_set_token_##bits(struct btrfs_map_token *token, \
		int size = sizeof(u##bits); \
		\
		ASSERT(token); \
		\
		if (token->kaddr && token->offset <= offset && \
		ASSERT(token->kaddr); \
		if (token->offset <= offset && \
		(token->offset + PAGE_SIZE >= offset + size)) { \
		kaddr = token->kaddr; \
		p = kaddr + part_offset - token->offset; \

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