Re: [PATCH 3/3] mds: fix race between cap issue and revoke

["Yan, Zheng" <zheng.z.yan@intel.com>]

This patch's title is wrong, please ignore it.

Thanks
Yan, Zheng

On 06/24/2013 02:41 PM, Yan, Zheng wrote:
> From: "Yan, Zheng" <zheng.z.yan@intel.com>
> 
> If we receive new caps from the auth MDS and the non-auth MDS is
> revoking the newly issued caps, we should release the caps from
> the non-auth MDS. The scenario is filelock's state changes from
> SYNC to LOCK. Non-auth MDS revokes Fc cap, the client gets Fc
> cap from the auth MDS at the same time.
> 
> Signed-off-by: Yan, Zheng <zheng.z.yan@intel.com>
> ---
>  fs/ceph/caps.c | 29 ++++++++++++++++++++---------
>  1 file changed, 20 insertions(+), 9 deletions(-)
> 
> diff --git a/fs/ceph/caps.c b/fs/ceph/caps.c
> index a8c616b..9b8b1aa 100644
> --- a/fs/ceph/caps.c
> +++ b/fs/ceph/caps.c
> @@ -813,22 +813,28 @@ int __ceph_caps_issued_mask(struct ceph_inode_info *ci, int mask, int touch)
>  /*
>   * Return true if mask caps are currently being revoked by an MDS.
>   */
> -int ceph_caps_revoking(struct ceph_inode_info *ci, int mask)
> +int __ceph_caps_revoking_other(struct ceph_inode_info *ci,
> +			       struct ceph_cap *ocap, int mask)
>  {
> -	struct inode *inode = &ci->vfs_inode;
>  	struct ceph_cap *cap;
>  	struct rb_node *p;
> -	int ret = 0;
>  
> -	spin_lock(&ci->i_ceph_lock);
>  	for (p = rb_first(&ci->i_caps); p; p = rb_next(p)) {
>  		cap = rb_entry(p, struct ceph_cap, ci_node);
> -		if (__cap_is_valid(cap) &&
> -		    (cap->implemented & ~cap->issued & mask)) {
> -			ret = 1;
> -			break;
> -		}
> +		if (cap != ocap && __cap_is_valid(cap) &&
> +		    (cap->implemented & ~cap->issued & mask))
> +			return 1;
>  	}
> +	return 0;
> +}
> +
> +int ceph_caps_revoking(struct ceph_inode_info *ci, int mask)
> +{
> +	struct inode *inode = &ci->vfs_inode;
> +	int ret;
> +
> +	spin_lock(&ci->i_ceph_lock);
> +	ret = __ceph_caps_revoking_other(ci, NULL, mask);
>  	spin_unlock(&ci->i_ceph_lock);
>  	dout("ceph_caps_revoking %p %s = %d\n", inode,
>  	     ceph_cap_string(mask), ret);
> @@ -2491,6 +2497,11 @@ static void handle_cap_grant(struct inode *inode, struct ceph_mds_caps *grant,
>  	} else {
>  		dout("grant: %s -> %s\n", ceph_cap_string(cap->issued),
>  		     ceph_cap_string(newcaps));
> +		/* non-auth MDS is revoking the newly grant caps ? */
> +		if (cap == ci->i_auth_cap &&
> +		    __ceph_caps_revoking_other(ci, cap, newcaps))
> +		    check_caps = 2;
> +
>  		cap->issued = newcaps;
>  		cap->implemented |= newcaps; /* add bits only, to
>  					      * avoid stepping on a
>