ext4: don't assume extents can't cross block groups when truncating
ext4: don't assume extents can't cross block groups when truncating

With the FLEX_BG layout, there is no reason why extents can't cross
block groups, so make the truncate code reserve enough credits so we
don't BUG if we come across such an extent.

Signed-off-by: "Theodore Ts'o" <4ed386e0495d3e109932df055831d9ec2f824927@mit.edu>

KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,KristFoundation/Programs