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btrfs: fix empty_zero_page misusage

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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>
This commit is contained in:
Chris Mason 2013-11-15 12:14:55 +01:00
parent 91aef86f3b
commit 46e0f66a0c
1 changed files with 7 additions and 2 deletions
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9
fs/btrfs/ioctl.c
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@ -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,