fix: btrfs: tracepoints: output proper root owner for trace_find_free_extent() (v5.10)

fix: btrfs: tracepoints: output proper root owner for trace_find_free_extent() (v5.10)

See upstream commit :

  commit 437490fed3b0c9ae21af8f70e0f338d34560842b
  Author: Qu Wenruo <wqu@suse.com>
  Date:   Tue Jul 28 09:42:49 2020 +0800

    btrfs: tracepoints: output proper root owner for trace_find_free_extent()

    The current trace event always output result like this:

     find_free_extent: root=2(EXTENT_TREE) len=16384 empty_size=0 flags=4(METADATA)
     find_free_extent: root=2(EXTENT_TREE) len=16384 empty_size=0 flags=4(METADATA)
     find_free_extent: root=2(EXTENT_TREE) len=8192 empty_size=0 flags=1(DATA)
     find_free_extent: root=2(EXTENT_TREE) len=8192 empty_size=0 flags=1(DATA)
     find_free_extent: root=2(EXTENT_TREE) len=4096 empty_size=0 flags=1(DATA)
     find_free_extent: root=2(EXTENT_TREE) len=4096 empty_size=0 flags=1(DATA)

    T's saying we're allocating data extent for EXTENT tree, which is not
    even possible.

    It's because we always use EXTENT tree as the owner for
    trace_find_free_extent() without using the @root from
    btrfs_reserve_extent().

    This patch will change the parameter to use proper @root for
    trace_find_free_extent():

    Now it looks much better:

     find_free_extent: root=5(FS_TREE) len=16384 empty_size=0 flags=36(METADATA|DUP)
     find_free_extent: root=5(FS_TREE) len=8192 empty_size=0 flags=1(DATA)
     find_free_extent: root=5(FS_TREE) len=16384 empty_size=0 flags=1(DATA)
     find_free_extent: root=5(FS_TREE) len=4096 empty_size=0 flags=1(DATA)
     find_free_extent: root=5(FS_TREE) len=8192 empty_size=0 flags=1(DATA)
     find_free_extent: root=5(FS_TREE) len=16384 empty_size=0 flags=36(METADATA|DUP)
     find_free_extent: root=7(CSUM_TREE) len=16384 empty_size=0 flags=36(METADATA|DUP)
     find_free_extent: root=2(EXTENT_TREE) len=16384 empty_size=0 flags=36(METADATA|DUP)
     find_free_extent: root=1(ROOT_TREE) len=16384 empty_size=0 flags=36(METADATA|DUP)

Signed-off-by: Michael Jeanson <mjeanson@efficios.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: I1d674064d29b31417e2acffdeb735f5052a87032