From f472d3c28385397b1a2891c4ec264b90cd6d2187 Mon Sep 17 00:00:00 2001 From: David Sterba Date: Thu, 30 Apr 2020 17:57:55 +0200 Subject: [PATCH] btrfs: optimize split page write in btrfs_set_token_##bits The fallback path calls helper write_extent_buffer to do write of the data spanning two extent buffer pages. As the size is known, we can do the write directly in two steps. This removes one function call and compiler can optimize memcpy as the sizes are known at compile time. The cached token address is set to the second page. Reviewed-by: Johannes Thumshirn Signed-off-by: David Sterba --- fs/btrfs/struct-funcs.c | 12 +++++++----- 1 file changed, 7 insertions(+), 5 deletions(-) diff --git a/fs/btrfs/struct-funcs.c b/fs/btrfs/struct-funcs.c index 7987d39..225ef6d 100644 --- a/fs/btrfs/struct-funcs.c +++ b/fs/btrfs/struct-funcs.c @@ -115,7 +115,8 @@ void btrfs_set_token_##bits(struct btrfs_map_token *token, \ const unsigned long idx = member_offset >> PAGE_SHIFT; \ const unsigned long oip = offset_in_page(member_offset); \ const int size = sizeof(u##bits); \ - __le##bits leres; \ + u8 lebytes[sizeof(u##bits)]; \ + const int part = PAGE_SIZE - oip; \ \ ASSERT(token); \ ASSERT(token->kaddr); \ @@ -125,16 +126,17 @@ void btrfs_set_token_##bits(struct btrfs_map_token *token, \ put_unaligned_le##bits(val, token->kaddr + oip); \ return; \ } \ + token->kaddr = page_address(token->eb->pages[idx]); \ + token->offset = idx << PAGE_SHIFT; \ if (oip + size <= PAGE_SIZE) { \ - token->kaddr = page_address(token->eb->pages[idx]); \ - token->offset = idx << PAGE_SHIFT; \ put_unaligned_le##bits(val, token->kaddr + oip); \ return; \ } \ + put_unaligned_le##bits(val, lebytes); \ + memcpy(token->kaddr + oip, lebytes, part); \ token->kaddr = page_address(token->eb->pages[idx + 1]); \ token->offset = (idx + 1) << PAGE_SHIFT; \ - leres = cpu_to_le##bits(val); \ - write_extent_buffer(token->eb, &leres, member_offset, size); \ + memcpy(token->kaddr, lebytes + part, size - part); \ } \ void btrfs_set_##bits(const struct extent_buffer *eb, void *ptr, \ unsigned long off, u##bits val) \ -- 2.7.4