Commit 9ab86c8e authored by Chris Mason's avatar Chris Mason
Browse files

Btrfs: kmap_atomic(KM_USER0) is safe for btrfs_readpage_end_io_hook 



None of the checksum verification code schedules, so we can use the faster
kmap_atomic

Signed-off-by: default avatarChris Mason <chris.mason@oracle.com>
parent cc7172de

fs/btrfs/inode.c

+3 −3
Original line number Diff line number Diff line
@@ -1748,7 +1748,7 @@ static int btrfs_readpage_end_io_hook(struct page *page, u64 start, u64 end, 
	} else {

		ret = get_state_private(io_tree, start, &private);

	}

	kaddr = kmap(page);

	kaddr = kmap_atomic(page, KM_USER0);

	if (ret)

		goto zeroit;
@@ -1757,7 +1757,7 @@ static int btrfs_readpage_end_io_hook(struct page *page, u64 start, u64 end, 
	if (csum != private)

		goto zeroit;



	kunmap(page);

	kunmap_atomic(kaddr, KM_USER0);

good:

	/* if the io failure tree for this inode is non-empty,

	 * check to see if we've recovered from a failed IO
@@ -1772,7 +1772,7 @@ static int btrfs_readpage_end_io_hook(struct page *page, u64 start, u64 end, 
	       (unsigned long long)private);

	memset(kaddr + offset, 1, end - start + 1);

	flush_dcache_page(page);

	kunmap(page);

	kunmap_atomic(kaddr, KM_USER0);

	if (private == 0)

		return 0;

	return -EIO;