linux-kernel - [PATCH v3 0/2] kernfs: use hashed mutex and spinlock in place of global ones

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Date:   Thu, 13 Jan 2022 21:42:57 +1100
From:   Imran Khan <imran.f.khan@...cle.com>
To:     tj@...nel.org, gregkh@...uxfoundation.org
Cc:     linux-kernel@...r.kernel.org
Subject: [PATCH v3 0/2] kernfs: use hashed mutex and spinlock in place of global ones

Reduce contention around global locks used in kernfs.

PATCH-1: Make global kernfs_open_file_mutex and kernfs_open_node_lock
	 hashed locks, where address of a kernfs_node acts as hash key.
	 This results in kernfs_node objects, whose address give the
	 different hash value, using different kernfs_open_file_mutex
	 and kernfs_open_node_lock rather than all kernfs_node objects
	 using the same kernfs_open_file_mutex and kernfs_open_node_lock
	 as was the case earlier.

PATCH-2: Use a hashed rw_semaphore to access permissions, so that we can
	 avoid contention around global per-fs rw_semaphore, seen if
	 multiple applications are executing inode_permission and
	 walk_component in parallel when trying to open sysfs file(s).

------------------------------------------------------------------

Changes since v2:
 - Remove RFC tag
 - Use hashed locks rather than using per kernfs_node specific lock
   (Suggested by Tejun Heo <tj@...nel.org>)
   

Imran Khan (2):
  kernfs: use hashed mutex and spinlock in place of global ones.
  kernfs: Reduce contention around global per-fs kernfs_rwsem.

 fs/kernfs/dir.c             |  8 +++++
 fs/kernfs/file.c            | 65 ++++++++++++++++-----------------
 fs/kernfs/inode.c           | 35 ++++++++++++------
 fs/kernfs/kernfs-internal.h | 71 +++++++++++++++++++++++++++++++++++++
 fs/kernfs/mount.c           | 11 ++++++
 5 files changed, 146 insertions(+), 44 deletions(-)


base-commit: a70bf4a85b43cb952bd39dd948b103b1b3eb2cf8
-- 
2.30.2