ceph: fetch inline data while getting Fcr cap refs

we can't use getattr to fetch inline data after getting Fcr caps,
because it can cause deadlock. The solution is try bringing inline
data to page cache when not holding any cap, and hope the inline
data page is still there after getting the Fcr caps. If the page
is still there, pin it in page cache for later IO.

Signed-off-by: Yan, Zheng <zyan@redhat.com>
ceph: sync read inline data

we can't use getattr to fetch inline data while holding Fr cap,
because it can cause deadlock. If we need to sync read inline data,
drop cap refs first, then use getattr to fetch inline data.

Signed-off-by: Yan, Zheng <zyan@redhat.com>
ceph: convert inline data to normal data before data write

Before any data write, convert inline data to normal data and set
i_inline_version to CEPH_INLINE_NONE. The OSD request that saves
inline data to object contains 3 operations (CMPXATTR, WRITE and
SETXATTR). It compares a xattr named 'inline_version' to prevent
old data overwrites newer data.

Signed-off-by: Yan, Zheng <zyan@redhat.com>
ceph: flush inline version

After converting inline data to normal data, client need to flush
the new i_inline_version (CEPH_INLINE_NONE) to MDS. This commit makes
cap messages (sent to MDS) contain inline_version and inline_data.
Client always converts inline data to normal data before data write,
so the inline data length part is always zero.

Signed-off-by: Yan, Zheng <zyan@redhat.com>
ceph: support inline data feature

Signed-off-by: Yan, Zheng <zyan@redhat.com>