fs: f2fs: initial import for 3.0.x

Change-Id: I34d45b198e89647c5a71abb22b3f02e4c01fd63c
vfs: export symbol d_find_any_alias()

Ceph needs this.

Change-Id: Idc5ab8a48b20699f3daf0637d35d055cf5a14441
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Sage Weil <sage@newdream.net>
Signed-off-by: Guangliang Zhao <gzhao@suse.com>
backport mnt_drop_write_file for 3.0.y

Change-Id: I022c03c6cdb34c7cdd16cd7a8d76e93748e93e22
add missing REQ_PRIO

Change-Id: Ibb5990037f8e76eaab4a199b15fb945feeca60f0
block: Add bio_for_each_segment_all()

Change-Id: I9707e30f619465460f38d5527d4ed963f59d1432
migrate other bio_for_each_segment calls

Change-Id: I97606e33d48ae535bb4104bb1c659326da9075ca
add missing posix_acl_create and posix_acl_chmod

Change-Id: I659301cba3e0e680e3adab3b83a9180fd7b508fa
f2fs: rename get_node_info to f2fs_get_node_info

Change-Id: Ibdae399db2e2aa2679cbf8d25e58041f8eb8554a
defconfig: enable f2fs

Change-Id: I6e61cbc799b5c04076114de301d41a16555d8098