From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: Jori Koolstra <jkoolstra@xs4all.nl>
Cc: Christian Brauner <brauner@kernel.org>,
Alexander Viro <viro@zeniv.linux.org.uk>, Jan Kara <jack@suse.cz>,
linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-api@vger.kernel.org, Jeff Layton <jlayton@kernel.org>,
NeilBrown <neil@brown.name>, Amir Goldstein <amir73il@gmail.com>,
Aleksa Sarai <cyphar@cyphar.com>
Subject: Re: [PATCH v7 07/12] kernfs: hold kernfs_iattr_rwsem when initializing a new inode
Date: Fri, 16 Oct 2026 16:50:04 +0200 [thread overview]
Message-ID: <2026101626-idealist-overshoot-26d6@gregkh> (raw)
In-Reply-To: <20261016143806.2946578-8-jkoolstra@xs4all.nl>
On Fri, Oct 16, 2026 at 04:38:01PM +0200, Jori Koolstra wrote:
> kernfs_refresh_inode() copies the uid, gid, timestamps and nlink of a
> kernfs_node into its VFS inode. Since commit 9caf69614225 ("kernfs:
> Introduce separate rwsem to protect inode attributes.") these are
> protected by kernfs_iattr_rwsem.
>
> kernfs_init_inode() calls kernfs_refresh_inode(), but was not converted.
> Its callers in turn hold kernfs_rwsem (kernfs_iop_lookup(),
> kernfs_fill_super()) or no lock at all (__kernfs_fh_to_dentry()),
> neither of which excludes a concurrent
> kernfs_setattr()/kernfs_iop_setattr().
>
> Take kernfs_iattr_rwsem for reading around the refresh in
> kernfs_init_inode(). This nests inside kernfs_rwsem, which matches
> kernfs_link_sibling() and kernfs_unlink_sibling().
>
> Also, kernfs_get_inode() then does not need to hold kernfs_rwsem, so
> drop it from kernfs_fill_super().
Oh, nice, this fixes the issue of kernfs not keeping the inode like we
talked about at LPC? Can't argue with this tiny patch, nice work!
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
next prev parent reply other threads:[~2026-10-16 14:50 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-10-16 14:37 [PATCH v7 00/12] vfs: add O_CREAT|O_DIRECTORY to open*(2) Jori Koolstra
2026-10-16 14:37 ` [PATCH v7 01/12] fs/namei.c: use trailing_slashes() Jori Koolstra
2026-10-16 14:37 ` [PATCH v7 02/12] vfs: prepare vfs_creat|mkdir_no_perm for reuse in lookup_open() Jori Koolstra
2026-10-16 14:37 ` [PATCH v7 03/12] vfs: lookup_open(): move setting FMODE_CREATED down Jori Koolstra
2026-10-16 14:37 ` [PATCH v7 04/12] vfs: move ->create check in lookup_open() to before try_break_deleg() Jori Koolstra
2026-10-16 14:37 ` [PATCH v7 05/12] vfs: lookup_open(): use vfs_create_no_perm() Jori Koolstra
2026-10-16 14:38 ` [PATCH v7 06/12] vfs: lookup_open(): lock the parent as I_MUTEX_PARENT Jori Koolstra
2026-10-16 14:38 ` [PATCH v7 07/12] kernfs: hold kernfs_iattr_rwsem when initializing a new inode Jori Koolstra
2026-10-16 14:50 ` Greg Kroah-Hartman [this message]
2026-10-16 14:38 ` [PATCH v7 08/12] vfs: add O_CREAT|O_DIRECTORY to open*(2) Jori Koolstra
2026-10-16 14:38 ` [PATCH v7 09/12] vfs: use finish_lookup() helper in __lookup_slow() and lookup_open() Jori Koolstra
2026-10-16 14:38 ` [PATCH v7 10/12] vfs: short-circuit MAY_WRITE access for O_DIRECTORY opens Jori Koolstra
2026-10-16 14:38 ` [PATCH v7 11/12] vfs: change ->create/->mkdir operations unavailable errno Jori Koolstra
2026-10-16 14:38 ` [PATCH v7 12/12] selftest: add tests for open*(O_CREAT|O_DIRECTORY) Jori Koolstra
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