From f4ca8c51d12631f1297d093f767c3a5ce5b95aff 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_##bits The helper write_extent_buffer is called 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. Reviewed-by: Johannes Thumshirn Signed-off-by: David Sterba --- fs/btrfs/struct-funcs.c | 14 +++++++++----- 1 file changed, 9 insertions(+), 5 deletions(-) diff --git a/fs/btrfs/struct-funcs.c b/fs/btrfs/struct-funcs.c index 63cab91507f83..7987d39106600 100644 --- a/fs/btrfs/struct-funcs.c +++ b/fs/btrfs/struct-funcs.c @@ -141,18 +141,22 @@ void btrfs_set_##bits(const struct extent_buffer *eb, void *ptr, \ { \ const unsigned long member_offset = (unsigned long)ptr + off; \ const unsigned long oip = offset_in_page(member_offset); \ + const unsigned long idx = member_offset >> PAGE_SHIFT; \ + char *kaddr = page_address(eb->pages[idx]); \ const int size = sizeof(u##bits); \ - __le##bits leres; \ + const int part = PAGE_SIZE - oip; \ + u8 lebytes[sizeof(u##bits)]; \ \ ASSERT(check_setget_bounds(eb, ptr, off, size)); \ if (oip + size <= PAGE_SIZE) { \ - const unsigned long idx = member_offset >> PAGE_SHIFT; \ - char *kaddr = page_address(eb->pages[idx]); \ put_unaligned_le##bits(val, kaddr + oip); \ return; \ } \ - leres = cpu_to_le##bits(val); \ - write_extent_buffer(eb, &leres, member_offset, size); \ + \ + put_unaligned_le##bits(val, lebytes); \ + memcpy(kaddr + oip, lebytes, part); \ + kaddr = page_address(eb->pages[idx + 1]); \ + memcpy(kaddr, lebytes + part, size - part); \ } DEFINE_BTRFS_SETGET_BITS(8) -- 2.30.2