[PATCH v2 2/5] fs: Use a percpu_counter to track nr_inodes

Avoids cache line ping pongs between cpus and prepare next patch,
because updates of nr_inodes dont need inode_lock anymore.

(socket8 bench result : no difference at this point)

Signed-off-by: Eric Dumazet <redacted>
---
fs/fs-writeback.c   |    2 +-
fs/inode.c          |   39 +++++++++++++++++++++++++++++++--------
include/linux/fs.h  |    3 +++
kernel/sysctl.c     |    4 ++--
mm/page-writeback.c |    2 +-
5 files changed, 38 insertions(+), 12 deletions(-)