[PATCH v2 0/3] vfs: Use per-cpu list for SB's s_inodes list

[Waiman Long <Waiman.Long@hpe.com>]

v1->v2:
 - Use separate structures for list head and nodes & provide a
   cleaner interface.
 - Use existing list_for_each_entry() or list_for_each_entry_safe()
   macros for each of the sb's s_inodes iteration functions instead
   of using list_for_each_entry_safe() for all of them which may not
   be safe in some cases.
 - Use an iterator interface to access all the nodes of a group of
   per-cpu lists. This approach is cleaner than the previous double-for
   macro which is kind of hacky. However, it does require more lines
   of code changes.
 - Add a preparatory patch 2 to extract out the per-inode codes from
   the superblock s_inodes list iteration functions to minimize code
   changes needed in the patch 3.

This patch is a replacement of my previous list batching patch -
https://lwn.net/Articles/674105/. Compared with the previous patch,
this one provides better performance and fairness. However, it also
requires a bit more changes in the VFS layer.

This patchset is a derivative of Andi Kleen's patch on "Initial per
cpu list for the per sb inode list"

https://git.kernel.org/cgit/linux/kernel/git/ak/linux-misc.git/commit/?h=hle315/combined&id=f1cf9e715a40f44086662ae3b29f123cf059cbf4

Patch 1 introduces the per-cpu list.

Patch 2 extracts out the per-inode codes from the superblock s_inodes
list iteration functions to minimize code changes needed in the
following patch.

Patch 3 modifies the superblock and inode structures to use the per-cpu
list. The corresponding functions that reference those structures are
modified.

Waiman Long (3):
  lib/percpu-list: Per-cpu list with associated per-cpu locks
  vfs: Refactor sb->s_inodes iteration functions
  vfs: Use per-cpu list for superblock's inode list

 fs/block_dev.c              |   71 +++++++++++--------
 fs/drop_caches.c            |   48 ++++++++-----
 fs/fs-writeback.c           |   85 ++++++++++++----------
 fs/inode.c                  |  163 ++++++++++++++++++++++++-------------------
 fs/notify/inode_mark.c      |  145 ++++++++++++++++++++------------------
 fs/quota/dquot.c            |  134 +++++++++++++++++++++--------------
 fs/super.c                  |    7 +-
 include/linux/fs.h          |   37 +++++++++-
 include/linux/percpu-list.h |   94 +++++++++++++++++++++++++
 lib/Makefile                |    2 +-
 lib/percpu-list.c           |  144 ++++++++++++++++++++++++++++++++++++++
 11 files changed, 643 insertions(+), 287 deletions(-)
 create mode 100644 include/linux/percpu-list.h
 create mode 100644 lib/percpu-list.c