From: Jori Koolstra <jkoolstra@xs4all.nl>
To: Christian Brauner <brauner@kernel.org>,
Alexander Viro <viro@zeniv.linux.org.uk>, Jan Kara <jack@suse.cz>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: 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>,
Jori Koolstra <jkoolstra@xs4all.nl>
Subject: [PATCH v7 07/12] kernfs: hold kernfs_iattr_rwsem when initializing a new inode
Date: Fri, 16 Oct 2026 16:38:01 +0200 [thread overview]
Message-ID: <20261016143806.2946578-8-jkoolstra@xs4all.nl> (raw)
In-Reply-To: <20261016143806.2946578-1-jkoolstra@xs4all.nl>
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().
Fixes: 9caf69614225 ("kernfs: Introduce separate rwsem to protect inode attributes.")
Signed-off-by: Jori Koolstra <jkoolstra@xs4all.nl>
---
fs/kernfs/inode.c | 3 ++-
fs/kernfs/mount.c | 3 ---
2 files changed, 2 insertions(+), 4 deletions(-)
diff --git a/fs/kernfs/inode.c b/fs/kernfs/inode.c
index abb286bc3474..83f2007498db 100644
--- a/fs/kernfs/inode.c
+++ b/fs/kernfs/inode.c
@@ -204,7 +204,8 @@ static void kernfs_init_inode(struct kernfs_node *kn, struct inode *inode)
inode->i_generation = kernfs_gen(kn);
set_default_inode_attr(inode, kn->mode);
- kernfs_refresh_inode(kn, inode);
+ scoped_guard(rwsem_read, &kernfs_root(kn)->kernfs_iattr_rwsem)
+ kernfs_refresh_inode(kn, inode);
/* initialize inode according to type */
switch (kernfs_type(kn)) {
diff --git a/fs/kernfs/mount.c b/fs/kernfs/mount.c
index a57399021c8b..202a5ca2bd34 100644
--- a/fs/kernfs/mount.c
+++ b/fs/kernfs/mount.c
@@ -283,7 +283,6 @@ struct dentry *kernfs_node_dentry(struct kernfs_node *kn,
static int kernfs_fill_super(struct super_block *sb, struct kernfs_fs_context *kfc)
{
struct kernfs_super_info *info = kernfs_info(sb);
- struct kernfs_root *kf_root = kfc->root;
struct inode *inode;
struct dentry *root;
@@ -304,9 +303,7 @@ static int kernfs_fill_super(struct super_block *sb, struct kernfs_fs_context *k
sb->s_shrink->seeks = 0;
/* get root inode, initialize and unlock it */
- down_read(&kf_root->kernfs_rwsem);
inode = kernfs_get_inode(sb, info->root->kn);
- up_read(&kf_root->kernfs_rwsem);
if (!inode) {
pr_debug("kernfs: could not get root inode\n");
return -ENOMEM;
--
2.56.0
next prev parent reply other threads:[~2026-10-16 14:37 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 ` Jori Koolstra [this message]
2026-10-16 14:50 ` [PATCH v7 07/12] kernfs: hold kernfs_iattr_rwsem when initializing a new inode Greg Kroah-Hartman
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
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20261016143806.2946578-8-jkoolstra@xs4all.nl \
--to=jkoolstra@xs4all.nl \
--cc=amir73il@gmail.com \
--cc=brauner@kernel.org \
--cc=cyphar@cyphar.com \
--cc=gregkh@linuxfoundation.org \
--cc=jack@suse.cz \
--cc=jlayton@kernel.org \
--cc=linux-api@vger.kernel.org \
--cc=linux-fsdevel@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=neil@brown.name \
--cc=viro@zeniv.linux.org.uk \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox