From: Hyunchul Lee <hyc.lee@gmail.com>
To: NeilBrown <neil@brown.name>
Cc: Miklos Szeredi <miklos@szeredi.hu>,
Amir Goldstein <amir73il@gmail.com>, Kees Cook <kees@kernel.org>,
Joel Granados <joel.granados@kernel.org>,
Richard Weinberger <richard@nod.at>,
Anton Ivanov <anton.ivanov@cambridgegreys.com>,
Johannes Berg <johannes@sipsolutions.net>,
Breno Leitao <leitao@debian.org>,
Andreas Hindborg <a.hindborg@kernel.org>,
Jan Harkes <jaharkes@cs.cmu.edu>, Hugh Dickins <hughd@google.com>,
Baolin Wang <baolin.wang@linux.alibaba.com>,
Namjae Jeon <linkinjeon@kernel.org>,
Carlos Maiolino <cem@kernel.org>,
Alexander Viro <viro@zeniv.linux.org.uk>,
Christian Brauner <brauner@kernel.org>,
Jeff Layton <jlayton@kernel.org>, Jan Kara <jack@suse.cz>,
linux-fsdevel@vger.kernel.org, fuse-devel@lists.linux.dev,
linux-kernel@vger.kernel.org, linux-unionfs@vger.kernel.org,
linux-um@lists.infradead.org, codalist@coda.cs.cmu.edu,
coda@cs.cmu.edu, linux-mm@kvack.org, ntfs@lists.linux.dev,
linux-xfs@vger.kernel.org
Subject: Re: [PATCH 1/7] VFS/xfs/ntfs: drop parent lock across d_alloc_parallel() in d_add_ci()
Date: Fri, 2 Oct 2026 15:01:30 +0900 [thread overview]
Message-ID: <ar9IuknaJqrGoF-j@hyunchul-PC02> (raw)
In-Reply-To: <20260929034158.1455429-2-neilb@ownmail.net>
On Tue, Sep 29, 2026 at 01:36:01PM +1000, NeilBrown wrote:
> From: NeilBrown <neil@brown.name>
>
> A proposed change will invert the lock ordering between
> d_alloc_parallel() and inode_lock() on the parent.
> When that happens it will not be safe to call d_alloc_parallel() while
> holding the parent lock - even shared.
>
> We don't need to keep the parent lock held when d_add_ci() is run - the
> VFS doesn't need it as dentry is exclusively held due to
> DCACHE_PAR_LOOKUP and the filesystem has finished its work.
>
> So drop and reclaim the lock (shared or exclusive as determined by
> LOOKUP_SHARED) to avoid future deadlock.
>
> Signed-off-by: NeilBrown <neil@brown.name>
For the NTFS part,
Looks good to me.
Reviewed-by: Hyunchul Lee <hyc.lee@gmail.com>
--
Thanks,
Hyunchul
next prev parent reply other threads:[~2026-10-02 6:01 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-09-29 3:36 [PATCH 0/7] multiple-filesystems: prepare for changes to VFS locking NeilBrown
2026-09-29 3:36 ` [PATCH 1/7] VFS/xfs/ntfs: drop parent lock across d_alloc_parallel() in d_add_ci() NeilBrown
2026-10-02 6:01 ` Hyunchul Lee [this message]
2026-09-29 3:36 ` [PATCH 2/7] shmem: use d_duplicate() NeilBrown
2026-09-29 3:36 ` [PATCH 3/7] coda: don't d_drop() early NeilBrown
2026-09-29 3:36 ` [PATCH 4/7] configfs: remove d_add() calls before configfs_attach_group() NeilBrown
2026-09-29 5:07 ` Al Viro
2026-10-01 1:32 ` NeilBrown
2026-09-29 3:36 ` [PATCH 5/7] hostfs: don't d_drop() before d_splice_alias() in hostfs_mkdir() NeilBrown
2026-09-29 3:36 ` [PATCH 6/7] procfs: drop parent lock for d_alloc_parallel() in iterate_shared() NeilBrown
2026-09-29 3:36 ` [PATCH 7/7] ovl: stop using lookup_one() in ovl_iterate() NeilBrown
2026-09-30 13:35 ` Amir Goldstein
2026-09-30 21:43 ` NeilBrown
2026-10-01 7:33 ` Amir Goldstein
2026-09-30 10:22 ` [syzbot ci] Re: multiple-filesystems: prepare for changes to VFS locking syzbot ci
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