FROMGIT: f2fs: compress: fix to cover normal cluster write with cp_rwsem

When we overwrite compressed cluster w/ normal cluster, we should
not unlock cp_rwsem during f2fs_write_raw_pages(), otherwise data
will be corrupted if partial blocks were persisted before CP & SPOR,
due to cluster metadata wasn't updated atomically.

Fixes: 4c8ff709 ("f2fs: support data compression")
Reviewed-by: Daeho Jeong <daehojeong@google.com>
Signed-off-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

Bug: 313549450
(cherry picked from commit fd244524
 https://git.kernel.org/pub/scm/linux/kernel/git/jaegeuk/f2fs.git

 dev)
Change-Id: I231eef3eb7ee5a105ad929718a6d1d67f4950dd2
Signed-off-by: Daeho Jeong <daehojeong@google.com>