ceph: decease session->s_trim_caps only after caps get trimmed
diff mbox

Message ID 20171130075358.7803-1-zyan@redhat.com
State New
Headers show

Commit Message

Yan, Zheng Nov. 30, 2017, 7:53 a.m. UTC
d_prune_aliases() does not prune dentry that has non-zero reference
count. If we want trim_caps() to trim 'N' caps, the first 'N' inodes
in session->s_caps are all directories with child dentry, trim_caps()
can fail to trim anything.

Cc: stable@vger.kernel.org
Signed-off-by: "Yan, Zheng" <zyan@redhat.com>
---
 fs/ceph/mds_client.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

Comments

Jeff Layton Nov. 30, 2017, noon UTC | #1
On Thu, 2017-11-30 at 15:53 +0800, Yan, Zheng wrote:
> d_prune_aliases() does not prune dentry that has non-zero reference
> count. If we want trim_caps() to trim 'N' caps, the first 'N' inodes
> in session->s_caps are all directories with child dentry, trim_caps()
> can fail to trim anything.
> 
> Cc: stable@vger.kernel.org
> Signed-off-by: "Yan, Zheng" <zyan@redhat.com>
> ---
>  fs/ceph/mds_client.c | 8 ++++++--
>  1 file changed, 6 insertions(+), 2 deletions(-)
> 
> diff --git a/fs/ceph/mds_client.c b/fs/ceph/mds_client.c
> index 80339e278ad8..da181acd4a61 100644
> --- a/fs/ceph/mds_client.c
> +++ b/fs/ceph/mds_client.c
> @@ -1490,16 +1490,20 @@ static int trim_caps_cb(struct inode *inode, struct ceph_cap *cap, void *arg)
>  	if ((used | wanted) & ~oissued & mine)
>  		goto out;   /* we need these caps */
>  
> -	session->s_trim_caps--;
>  	if (oissued) {
>  		/* we aren't the only cap.. just remove us */
>  		__ceph_remove_cap(cap, true);
> +		session->s_trim_caps--;
>  	} else {
> +		int refs;
>  		/* try dropping referring dentries */
>  		spin_unlock(&ci->i_ceph_lock);
>  		d_prune_aliases(inode);
> +		refs = atomic_read(&inode->i_count);
> +		if (refs == 1)
> +			session->s_trim_caps--;
>  		dout("trim_caps_cb %p cap %p  pruned, count now %d\n",
> -		     inode, cap, atomic_read(&inode->i_count));
> +		     inode, cap, refs);
>  		return 0;
>  	}
>  

Reviewed-by: Jeff Layton <jlayton@redhat.com>
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Patch
diff mbox

diff --git a/fs/ceph/mds_client.c b/fs/ceph/mds_client.c
index 80339e278ad8..da181acd4a61 100644
--- a/fs/ceph/mds_client.c
+++ b/fs/ceph/mds_client.c
@@ -1490,16 +1490,20 @@  static int trim_caps_cb(struct inode *inode, struct ceph_cap *cap, void *arg)
 	if ((used | wanted) & ~oissued & mine)
 		goto out;   /* we need these caps */
 
-	session->s_trim_caps--;
 	if (oissued) {
 		/* we aren't the only cap.. just remove us */
 		__ceph_remove_cap(cap, true);
+		session->s_trim_caps--;
 	} else {
+		int refs;
 		/* try dropping referring dentries */
 		spin_unlock(&ci->i_ceph_lock);
 		d_prune_aliases(inode);
+		refs = atomic_read(&inode->i_count);
+		if (refs == 1)
+			session->s_trim_caps--;
 		dout("trim_caps_cb %p cap %p  pruned, count now %d\n",
-		     inode, cap, atomic_read(&inode->i_count));
+		     inode, cap, refs);
 		return 0;
 	}