Re: [PATCH 07/15] reconnect_one(): use lookup_one_len_unlocked()

From: J. Bruce Fields
Date: Mon Apr 18 2016 - 15:23:56 EST


On Sat, Apr 16, 2016 at 01:55:19AM +0100, Al Viro wrote:
> From: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
>
> ... and explain the non-obvious logics in case when lookup yields
> a different dentry.

ACK to this independent of the rest of the series, my only minor gripe
is that the point made in this new comment is also made at
out_reconnected: and at the head of reconnect_one(). And would also
apply at the other "goto out_reconnected". My preference is to leave
things as they are, but if you found it easy to overlook maybe just
something like:

- goto out_reconnected;
+ goto out_reconnected; /* see comment there*/

would be helpful. And/or improving the final comment.

--b.

>
> Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
> ---
> fs/exportfs/expfs.c | 10 +++++++---
> 1 file changed, 7 insertions(+), 3 deletions(-)
>
> diff --git a/fs/exportfs/expfs.c b/fs/exportfs/expfs.c
> index c46f1a1..402c5ca 100644
> --- a/fs/exportfs/expfs.c
> +++ b/fs/exportfs/expfs.c
> @@ -143,14 +143,18 @@ static struct dentry *reconnect_one(struct vfsmount *mnt,
> if (err)
> goto out_err;
> dprintk("%s: found name: %s\n", __func__, nbuf);
> - inode_lock(parent->d_inode);
> - tmp = lookup_one_len(nbuf, parent, strlen(nbuf));
> - inode_unlock(parent->d_inode);
> + tmp = lookup_one_len_unlocked(nbuf, parent, strlen(nbuf));
> if (IS_ERR(tmp)) {
> dprintk("%s: lookup failed: %d\n", __func__, PTR_ERR(tmp));
> goto out_err;
> }
> if (tmp != dentry) {
> + /*
> + * Somebody has renamed it since exportfs_get_name();
> + * great, since it could've only been renamed if it
> + * got looked up and thus connected, and it would
> + * remain connected afterwards. We are done.
> + */
> dput(tmp);
> goto out_reconnected;
> }
> --
> 2.8.0.rc3
>
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