Commit 46e0f66a authored Nov 15, 2013 by Chris Mason

btrfs: fix empty_zero_page misusage



Heiko Carstens noticed that btrfs was using empty_zero_page
incorrectly.  He explained:

	The definition of empty_zero_page is architecture specific.  It
	is (currently) either a character array, an unsigned long
	containing the address of the empty_zero_page, or even worse
	only the address of the struct page belonging to the
	empty_zero_page.

This commit changes btrfs to use a for-loop instead.  On x86
the resulting .ko is smaller, and we're no longer worrying about
how each arch builds its zeros.

Reported-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>

parent 91aef86f

fs/btrfs/ioctl.c

+7 −2

Original line number	Diff line number	Diff line
		@@ -368,8 +368,13 @@ static noinline int btrfs_ioctl_fitrim(struct file file, void __user arg)

		int btrfs_is_empty_uuid(u8 *uuid)
		{
		BUILD_BUG_ON(BTRFS_UUID_SIZE > PAGE_SIZE);
		return !memcmp(uuid, empty_zero_page, BTRFS_UUID_SIZE);
		int i;

		for (i = 0; i < BTRFS_UUID_SIZE; i++) {
		if (uuid[i])
		return 0;
		}
		return 1;
		}

		static noinline int create_subvol(struct inode *dir,

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