[PATCH 0/2 v7] add ioctl/sysfs to donate file-backed pages

[Jaegeuk Kim <jaegeuk@kernel.org>]

Note, let me keep improving this patch set, while trying to get some feedbacks
from MM and API folks from [1].

If users clearly know which file-backed pages to reclaim in system view, they
can use this ioctl() to register in advance and reclaim all at once later.

I'd like to propose this API in F2FS only, since
1) the use-case is quite limited in Android at the moment. Once it's generall
accepted with more use-cases, happy to propose a generic API such as fadvise.
Please chime in, if there's any needs.

2) it's file-backed pages which requires to maintain the list of inode objects.
I'm not sure this fits in MM tho, also happy to listen to any feedback.

[1] https://lore.kernel.org/lkml/Z4qmF2n2pzuHqad_@google.com/

Change log from v6:
 - change sysfs entry name to reclaim_caches_kb

Jaegeuk Kim (2):
  f2fs: register inodes which is able to donate pages
  f2fs: add a sysfs entry to request donate file-backed pages

 Documentation/ABI/testing/sysfs-fs-f2fs |  7 +++
 fs/f2fs/debug.c                         |  3 ++
 fs/f2fs/f2fs.h                          | 14 +++++-
 fs/f2fs/file.c                          | 65 +++++++++++++++++++++++++
 fs/f2fs/inode.c                         | 14 ++++++
 fs/f2fs/shrinker.c                      | 33 +++++++++++++
 fs/f2fs/super.c                         |  1 +
 fs/f2fs/sysfs.c                         |  8 +++
 include/uapi/linux/f2fs.h               |  7 +++
 9 files changed, 151 insertions(+), 1 deletion(-)

-- 
2.48.1.262.g85cc9f2d1e-goog