include/linux/mm.h: move nr_free_buffer_pages from swap.h to mm.h

nr_free_buffer_pages could be exposed through mm.h instead of swap.h.
The advantage of this change is that it can reduce the obsolete
includes.  For example, net/ipv4/tcp.c wouldn't need swap.h any more
since it has already included mm.h.  Similarly, after checking all the
other files, it comes that tcp.c, udp.c meter.c ,...  follow the same
rule, so these files can have swap.h removed too.

Moreover, after preprocessing all the files that use
nr_free_buffer_pages, it turns out that those files have already
included mm.h.Thus, we can move nr_free_buffer_pages from swap.h to mm.h
safely.  This change will not affect the compilation of other files.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Mianhan Liu <[email protected]>
Cc: Jakub Kicinski <[email protected]>
CC: Ulf Hansson <[email protected]>
Cc: "David S . Miller" <[email protected]>
Cc: Simon Horman <[email protected]>
Cc: Pravin B Shelar <[email protected]>
Cc: Vlad Yasevich <[email protected]>
Cc: Marcelo Ricardo Leitner <[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