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>
diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index 1d04b55..64a0876 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -368,8 +368,13 @@
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,