Re: [Linux-stable-mirror] [PATCH] ceph: decease session->s_trim_caps only after caps get trimmed

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