linux-kernel - [PATCH v2 0/3] kernfs: Introduce separate rwsem to protect inode

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Message-Id: <20230309110932.2889010-1-imran.f.khan@oracle.com>
Date:   Thu,  9 Mar 2023 22:09:29 +1100
From:   Imran Khan <imran.f.khan@...cle.com>
To:     tj@...nel.org, gregkh@...uxfoundation.org, viro@...iv.linux.org.uk,
        willy@...radead.org
Cc:     linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org,
        joe.jin@...cle.com
Subject: [PATCH v2 0/3] kernfs: Introduce separate rwsem to protect inode

Changes since v1:
 - Remove kernfs_rwsem from kernfs_notify_workfn
 - Include Matthew's "Reviewed-by" tag for Patch-3
-------------------------------------------------------------------
Original cover letter

This change set is consolidating the changes discussed and/or mentioned
in [1] and [2]. I have not received any feedback about any of the
patches included in this change set, so I am rebasing them on current
linux-next tip and bringing them all in one place.

As mentioned in [1], since changing per-fs kernfs_rwsem into a hashed
rwsem is not working for all scenarios, PATCH-1 here tries to address
the same issue with the help of another newly introduced per-fs rwsem.
PATCH-2 and PATCH-3 are basically resend of PATCH-1 and PATCH-2
respectively in [2].

It would be really helpful if I could get some feedback about this
changeset so that we can reduce the kernfs_rwsem contention and make
sysfs access more scalable for large-scale systems.

The patches in this change set are as follows:

PATCH-1: kernfs: Introduce separate rwsem to protect inode attributes.

PATCH-2: kernfs: Use a per-fs rwsem to protect per-fs list of
kernfs_super_info.

PATCH-3: kernfs: change kernfs_rename_lock into a read-write lock.

Imran Khan (3):
  kernfs: Introduce separate rwsem to protect inode attributes.
  Use a per-fs rwsem to protect per-fs list of kernfs_super_info.
  kernfs: change kernfs_rename_lock into a read-write lock.

 fs/kernfs/dir.c             | 26 +++++++++++++++++---------
 fs/kernfs/file.c            |  2 ++
 fs/kernfs/inode.c           | 16 ++++++++--------
 fs/kernfs/kernfs-internal.h |  2 ++
 fs/kernfs/mount.c           |  8 ++++----
 5 files changed, 33 insertions(+), 21 deletions(-)

base-commit: 7f7a8831520f12a3cf894b0627641fad33971221

[1]:https://lore.kernel.org/all/74969b22-e0b6-30bd-a1f0-132f4b8485cf@oracle.com/
[2]:https://lore.kernel.org/all/20220810111017.2267160-1-imran.f.khan@oracle.com/
-------------------------------------------------------------------

Imran Khan (3):
  kernfs: Introduce separate rwsem to protect inode attributes.
  kernfs: Use a per-fs rwsem to protect per-fs list of
    kernfs_super_info.
  kernfs: change kernfs_rename_lock into a read-write lock.

 fs/kernfs/dir.c             | 26 +++++++++++++++++---------
 fs/kernfs/file.c            |  4 ++--
 fs/kernfs/inode.c           | 16 ++++++++--------
 fs/kernfs/kernfs-internal.h |  2 ++
 fs/kernfs/mount.c           |  8 ++++----
 5 files changed, 33 insertions(+), 23 deletions(-)

-- 
2.34.1