xfs: create xfs_bmap_util.[ch]

There is a bunch of code in xfs_bmap.c that is kernel specific and
not shared with userspace. To minimise the difference between the
kernel and userspace code, shift this unshared code to
xfs_bmap_util.c, and the declarations to xfs_bmap_util.h.

The biggest issue here is xfs_bmap_finish() - userspace has it's own
definition of this function, and so we need to move it out of
xfs_bmap.[ch]. This means several other files need to include
xfs_bmap_util.h as well.

It also introduces and interesting dance for the stack switching
code in xfs_bmapi_allocate(). The stack switching/workqueue code is
actually moved to xfs_bmap_util.c, so that userspace can simply use
a #define in a header file to connect the dots without needing to
know about the stack switch code at all.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Mark Tinguely <tinguely@sgi.com>
Signed-off-by: Ben Myers <bpm@sgi.com>

diff --cc fs/xfs/Makefile
Simple merge

diff --cc fs/xfs/xfs_aops.c
Simple merge

diff --cc fs/xfs/xfs_attr.c
Simple merge

diff --cc fs/xfs/xfs_attr_remote.c
Simple merge

diff --cc fs/xfs/xfs_bmap.c
Simple merge

diff --cc fs/xfs/xfs_bmap.h
Simple merge

diff --cc fs/xfs/xfs_bmap_util.c
Simple merge

diff --cc fs/xfs/xfs_bmap_util.h
Simple merge

diff --cc fs/xfs/xfs_dfrag.c
Simple merge

diff --cc fs/xfs/xfs_dquot.c
Simple merge

diff --cc fs/xfs/xfs_filestream.c
Simple merge

diff --cc fs/xfs/xfs_inode.c
Simple merge

diff --cc fs/xfs/xfs_ioctl.c
Simple merge

diff --cc fs/xfs/xfs_iomap.c
Simple merge

diff --cc fs/xfs/xfs_iops.c
Simple merge

diff --cc fs/xfs/xfs_rename.c
Simple merge

diff --cc fs/xfs/xfs_rtalloc.c
Simple merge

diff --cc fs/xfs/xfs_symlink.c
Simple merge

diff --cc fs/xfs/xfs_trans_resv.c
Simple merge

diff --cc fs/xfs/xfs_vnodeops.c
Simple merge