Btrfs: Init address_space->writeback_index properly
Btrfs: Init address_space->writeback_index properly

The writeback_index field is used by write_cache_pages to pick up where
writeback on a given inode left off.  But, it is never set to a sane
value, so writeback can often start at a random offset in the file.

Kernels 2.6.28 and higher will have this fixed, but for everyone else,
we also fill in the value in btrfs.

Signed-off-by: Chris Mason <a169954b4cb1a46cee25f659d3bddfebe02b5fba@oracle.com>

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