Date:	Sun, 3 Apr 2011 13:55:29 -0500
From:	"Serge E. Hallyn" <serge@...lyn.com>
To:	ntl@...ox.com
Cc:	linux-kernel@...r.kernel.org, containers@...ts.linux-foundation.org
Subject: Re: [PATCH 03/10] Introduce has_locks_with_owner() helper

Quoting ntl@...ox.com (ntl@...ox.com):
> From: Nathan Lynch <ntl@...ox.com>
> 
> Support for file locks is in the works, but until that is done
> checkpoint needs to fail when an open file has locks.
> 
> Based on original "find_locks_with_owner" patch by Dave Hansen.
> 
> Signed-off-by: Dave Hansen <dave@...ux.vnet.ibm.com>
> [ntl: changed name and return type to clearly express semantics]
> Signed-off-by: Nathan Lynch <ntl@...ox.com>

Acked-by: Serge Hallyn <serge.hallyn@...ntu.com>

> ---
>  fs/locks.c         |   35 +++++++++++++++++++++++++++++++++++
>  include/linux/fs.h |    6 ++++++
>  2 files changed, 41 insertions(+), 0 deletions(-)
> 
> diff --git a/fs/locks.c b/fs/locks.c
> index 8729347..961e17f 100644
> --- a/fs/locks.c
> +++ b/fs/locks.c
> @@ -2037,6 +2037,41 @@ void locks_remove_posix(struct file *filp, fl_owner_t owner)
>  
>  EXPORT_SYMBOL(locks_remove_posix);
>  
> +bool has_locks_with_owner(struct file *filp, fl_owner_t owner)
> +{
> +	struct inode *inode = filp->f_path.dentry->d_inode;
> +	struct file_lock **inode_fl;
> +	bool ret = false;
> +
> +	lock_flocks();
> +	for_each_lock(inode, inode_fl) {
> +		struct file_lock *fl = *inode_fl;
> +		/*
> +		 * We could use posix_same_owner() along with a 'fake'
> +		 * file_lock.  But, the fake file will never have the
> +		 * same fl_lmops as the fl that we are looking for and
> +		 * posix_same_owner() would just fall back to this
> +		 * check anyway.
> +		 */
> +		if (IS_POSIX(fl)) {
> +			if (fl->fl_owner == owner) {
> +				ret = true;
> +				break;
> +			}
> +		} else if (IS_FLOCK(fl) || IS_LEASE(fl)) {
> +			if (fl->fl_file == filp) {
> +				ret = true;
> +				break;
> +			}
> +		} else {
> +			WARN(1, "unknown file lock type, fl_flags: %x",
> +				fl->fl_flags);
> +		}
> +	}
> +	unlock_flocks();
> +	return ret;
> +}
> +
>  /*
>   * This function is called on the last close of an open file.
>   */
> diff --git a/include/linux/fs.h b/include/linux/fs.h
> index 090f0ea..315ded4 100644
> --- a/include/linux/fs.h
> +++ b/include/linux/fs.h
> @@ -1138,6 +1138,7 @@ extern void locks_remove_posix(struct file *, fl_owner_t);
>  extern void locks_remove_flock(struct file *);
>  extern void locks_release_private(struct file_lock *);
>  extern void posix_test_lock(struct file *, struct file_lock *);
> +extern bool has_locks_with_owner(struct file *filp, fl_owner_t owner);
>  extern int posix_lock_file(struct file *, struct file_lock *, struct file_lock *);
>  extern int posix_lock_file_wait(struct file *, struct file_lock *);
>  extern int posix_unblock_lock(struct file *, struct file_lock *);
> @@ -1208,6 +1209,11 @@ static inline void locks_remove_posix(struct file *filp, fl_owner_t owner)
>  	return;
>  }
>  
> +static inline bool has_locks_with_owner(struct file *filp, fl_owner_t owner)
> +{
> +	return false;
> +}
> +
>  static inline void locks_remove_flock(struct file *filp)
>  {
>  	return;
> -- 
> 1.7.4
> 
> _______________________________________________
> Containers mailing list
> Containers@...ts.linux-foundation.org
> https://lists.linux-foundation.org/mailman/listinfo/containers
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