[PATCH 4/6] afs: Use RCU inode cache search for callback resolution [ver #2]

David Howells
2019-04-25T15:02:27Z

Search the inode cache under "RCU conditions" when trying to find a vnode
to break the callback on. We don't want to be taking the icache lock if we
can avoid it.

Signed-off-by: David Howells <dhowells@redhat.com>
cc: linux-afs@lists.infradead.org
---

fs/afs/callback.c | 12 +++++++++---
1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/fs/afs/callback.c b/fs/afs/callback.c
index 128f2dbe256a..3d0280d4fbf0 100644
--- a/fs/afs/callback.c
+++ b/fs/afs/callback.c
@@ -251,6 +251,7 @@ static void afs_break_one_callback(struct afs_server *server,
struct afs_vnode *vnode;
struct inode *inode;

+ rcu_read_lock();
read_lock(&server->cb_break_lock);
hlist_for_each_entry(vi, &server->cb_volumes, srv_link) {
if (vi->vid < fid->vid)
@@ -284,18 +285,23 @@ static void afs_break_one_callback(struct afs_server *server,
} else {
data.volume = NULL;
data.fid = *fid;
- inode = ilookup5_nowait(cbi->sb, fid->vnode,
- afs_iget5_test, &data);
+
+ /* See if we can find a matching inode - even an I_NEW
+ * inode needs to be marked as it can have its callback
+ * broken before we finish setting up the local inode.
+ */
+ inode = find_inode_rcu(cbi->sb, fid->vnode,
+ afs_iget5_test, &data);
if (inode) {
vnode = AFS_FS_I(inode);
afs_break_callback(vnode);
- iput(inode);
}
}
}

out:
read_unlock(&server->cb_break_lock);
+ rcu_read_unlock();
}

/*