linux-phytec-fsl

f2fs: do not preallocate block unaligned to 4KB

Previously f2fs_preallocate_blocks() tries to allocate unaligned blocks.
In f2fs_write_begin(), however, prepare_write_begin() does not skip its
allocation due to (len != 4KB).
So, it needs locking node page twice unexpectedly.

Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>