On Fri, 2011-08-19 at 12:56 -0400, David Teigland wrote:
> When i_flock contains only flocks, the posix unlock is
> unnecessary, but called anyway. On gfs2, ocfs2, and
> possibly others with f_op->lock, the posix unlock can
> be costly, so only do it if posix locks exist.
>
> Signed-off-by: David Teigland <teigland@xxxxxxxxxx>
> ---
> fs/locks.c | 17 ++++++++++++++++-
> 1 files changed, 16 insertions(+), 1 deletions(-)
>
> diff --git a/fs/locks.c b/fs/locks.c
> index 703f545..d47f497 100644
> --- a/fs/locks.c
> +++ b/fs/locks.c
> @@ -1982,15 +1982,30 @@ out:
> void locks_remove_posix(struct file *filp, fl_owner_t owner)
> {
> struct file_lock lock;
> + struct file_lock **before;
> + struct inode *inode;
>
> /*
> * If there are no locks held on this file, we don't need to call
> * posix_lock_file(). Another process could be setting a lock on this
> * file at the same time, but we wouldn't remove that lock anyway.
> */
> - if (!filp->f_path.dentry->d_inode->i_flock)
> + inode = filp->f_path.dentry->d_inode;
> +
> + if (!inode->i_flock)
> return;
>
> + lock_flocks();
> + for_each_lock(inode, before) {
> + struct file_lock *fl = *before;
> + if (IS_POSIX(fl))
> + goto do_unlock;
> + }
> + unlock_flocks();
> + return;
> +
> +do_unlock:
> + unlock_flocks();
> lock.fl_type = F_UNLCK;
> lock.fl_flags = FL_POSIX | FL_CLOSE;
> lock.fl_start = 0;
This assumes that all locks are mirrored in inode->i_flock, which may
not be the case if the filesystem implements its own f_op->lock(). The
right place for this optimisation would be in your filesystem callback.
Cheers
Trond
--
Trond Myklebust
Linux NFS client maintainer
NetApp
Trond.Myklebust@xxxxxxxxxx
www.netapp.com
--
To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
