mm/thp: flush file for !is_shmem PageDirty() case in collapse_file()

For non-shmem file THPs, khugepaged only collapses read only .text
mapping (VM_DENYWRITE).  These pages should not be dirty except the case
where the file hasn't been flushed since first write.

Call filemap_flush() in collapse_file() to accelerate the write back in
such cases.

Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Song Liu <[email protected]>
Cc: Kirill A. Shutemov <[email protected]>
Cc: Hugh Dickins <[email protected]>
Cc: William Kucharski <[email protected]>
Cc: Johannes Weiner <[email protected]>
Cc: Matthew Wilcox <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

0 files changed, 0 insertions, 0 deletions