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From:   Chuck Lever III <chuck.lever@oracle.com>
To:     Dai Ngo <dai.ngo@oracle.com>
CC:     Bruce Fields <bfields@fieldses.org>,
        Jeff Layton <jlayton@redhat.com>,
        Al Viro <viro@zeniv.linux.org.uk>,
        Linux NFS Mailing List <linux-nfs@vger.kernel.org>,
        "linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>
Subject: Re: [PATCH RFC v16 01/11] fs/lock: add helper
 locks_owner_has_blockers to check for blockers
Thread-Topic: [PATCH RFC v16 01/11] fs/lock: add helper
 locks_owner_has_blockers to check for blockers
Thread-Index: AQHYNbbNyCdZ5ld6D0G7GIwxFtXS4azCGKAA
Date:   Wed, 16 Mar 2022 14:27:57 +0000
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> On Mar 11, 2022, at 9:13 PM, Dai Ngo <dai.ngo@oracle.com> wrote:
>=20
> Add helper locks_owner_has_blockers to check if there is any blockers
> for a given lockowner.
>=20
> Signed-off-by: Dai Ngo <dai.ngo@oracle.com>
> ---
> fs/locks.c         | 28 ++++++++++++++++++++++++++++
> include/linux/fs.h |  7 +++++++
> 2 files changed, 35 insertions(+)
>=20
> diff --git a/fs/locks.c b/fs/locks.c
> index 050acf8b5110..53864eb99dc5 100644
> --- a/fs/locks.c
> +++ b/fs/locks.c
> @@ -300,6 +300,34 @@ void locks_release_private(struct file_lock *fl)
> }
> EXPORT_SYMBOL_GPL(locks_release_private);
>=20
> +/**
> + * locks_owner_has_blockers - Check for blocking lock requests
> + * @flctx: file lock context
> + * @owner: lock owner
> + *
> + * Return values:
> + *   %true: @owner has at least one blocker
> + *   %false: @owner has no blockers
> + */
> +bool locks_owner_has_blockers(struct file_lock_context *flctx,
> +		fl_owner_t owner)
> +{
> +	struct file_lock *fl;
> +
> +	spin_lock(&flctx->flc_lock);
> +	list_for_each_entry(fl, &flctx->flc_posix, fl_list) {
> +		if (fl->fl_owner !=3D owner)
> +			continue;
> +		if (!list_empty(&fl->fl_blocked_requests)) {
> +			spin_unlock(&flctx->flc_lock);
> +			return true;
> +		}
> +	}
> +	spin_unlock(&flctx->flc_lock);
> +	return false;
> +}
> +EXPORT_SYMBOL_GPL(locks_owner_has_blockers);
> +
> /* Free a lock which is not in use. */
> void locks_free_lock(struct file_lock *fl)
> {
> diff --git a/include/linux/fs.h b/include/linux/fs.h
> index 831b20430d6e..da8ae38f471c 100644
> --- a/include/linux/fs.h
> +++ b/include/linux/fs.h
> @@ -1200,6 +1200,8 @@ extern void lease_unregister_notifier(struct notifi=
er_block *);
> struct files_struct;
> extern void show_fd_locks(struct seq_file *f,
> 			 struct file *filp, struct files_struct *files);
> +extern bool locks_owner_has_blockers(struct file_lock_context *flctx,
> +			fl_owner_t owner);
> #else /* !CONFIG_FILE_LOCKING */
> static inline int fcntl_getlk(struct file *file, unsigned int cmd,
> 			      struct flock __user *user)
> @@ -1335,6 +1337,11 @@ static inline int lease_modify(struct file_lock *f=
l, int arg,
> struct files_struct;
> static inline void show_fd_locks(struct seq_file *f,
> 			struct file *filp, struct files_struct *files) {}
> +extern bool locks_owner_has_blockers(struct file_lock_context *flctx,
> +			fl_owner_t owner)

Here's the problem, Dai.

This empty function needs to be declared "static inline" not "extern".


> +{
> +	return false;
> +}
> #endif /* !CONFIG_FILE_LOCKING */
>=20
> static inline struct inode *file_inode(const struct file *f)
> --=20
> 2.9.5
>=20

--
Chuck Lever