[PATCH 4.4 008/115] ceph: drop negative child dentries before try pruning inodes alias

Greg Kroah-Hartman
2017-12-18T18:14:11Z

From: Yan, Zheng <zyan@redhat.com>

commit 040d786032bf59002d374b86d75b04d97624005c upstream.

Negative child dentry holds reference on inode's alias, it makes
d_prune_aliases() do nothing.

Signed-off-by: "Yan, Zheng" <zyan@redhat.com>
Reviewed-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
fs/ceph/mds_client.c | 42 ++++++++++++++++++++++++++++++++++++++----
1 file changed, 38 insertions(+), 4 deletions(-)

--- a/fs/ceph/mds_client.c
+++ b/fs/ceph/mds_client.c
@@ -1400,6 +1400,29 @@ static int __close_session(struct ceph_m
return request_close_session(mdsc, session);
}

+static bool drop_negative_children(struct dentry *dentry)
+{
+ struct dentry *child;
+ bool all_negative = true;
+
+ if (!d_is_dir(dentry))
+ goto out;
+
+ spin_lock(&dentry->d_lock);
+ list_for_each_entry(child, &dentry->d_subdirs, d_child) {
+ if (d_really_is_positive(child)) {
+ all_negative = false;
+ break;
+ }
+ }
+ spin_unlock(&dentry->d_lock);
+
+ if (all_negative)
+ shrink_dcache_parent(dentry);
+out:
+ return all_negative;
+}
+
/*
* Trim old(er) caps.
*
@@ -1445,16 +1468,27 @@ static int trim_caps_cb(struct inode *in
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 {
+ struct dentry *dentry;
/* try dropping referring dentries */
spin_unlock(&ci->i_ceph_lock);
- d_prune_aliases(inode);
- dout("trim_caps_cb %p cap %p pruned, count now %d\n",
- inode, cap, atomic_read(&inode->i_count));
+ dentry = d_find_any_alias(inode);
+ if (dentry && drop_negative_children(dentry)) {
+ int count;
+ dput(dentry);
+ d_prune_aliases(inode);
+ count = atomic_read(&inode->i_count);
+ if (count == 1)
+ session->s_trim_caps--;
+ dout("trim_caps_cb %p cap %p pruned, count now %d\n",
+ inode, cap, count);
+ } else {
+ dput(dentry);
+ }
return 0;
}