[PATCH] ceph: wake waiters on any IMPORT that grants new caps

[Jeff Layton <jlayton@kernel.org>]

I've noticed an intermittent hang waiting for caps in some testing. What
I see is that the client will try to get caps for an operation (e.g. a
read), and ends up waiting on the waitqueue forever. The caps debugfs
file however shows that the caps it's waiting on have already been
granted.

The current grant handling code will wake the waitqueue when it sees
that there are newly-granted caps in the issued set. On an import
however, we'll end up adding a new cap first, which fools the logic into
thinking that nothing has changed. A later hack in the code works around
this, but only for auth caps.

Ensure we wake the waiters whenever we get an IMPORT that grants new
caps for the inode.

URL: https://tracker.ceph.com/issues/54044
Signed-off-by: Jeff Layton <jlayton@kernel.org>
---
 fs/ceph/caps.c | 23 ++++++++++++-----------
 1 file changed, 12 insertions(+), 11 deletions(-)

I'm still testing this patch, but I think this may be the cause of some
mysterious hangs I've hit in testing.

diff --git a/fs/ceph/caps.c b/fs/ceph/caps.c
index e668cdb9c99e..06b65a68e920 100644
--- a/fs/ceph/caps.c
+++ b/fs/ceph/caps.c
@@ -3541,21 +3541,22 @@ static void handle_cap_grant(struct inode *inode,
 			fill_inline = true;
 	}
 
-	if (ci->i_auth_cap == cap &&
-	    le32_to_cpu(grant->op) == CEPH_CAP_OP_IMPORT) {
+	if (le32_to_cpu(grant->op) == CEPH_CAP_OP_IMPORT) {
 		if (newcaps & ~extra_info->issued)
 			wake = true;
 
-		if (ci->i_requested_max_size > max_size ||
-		    !(le32_to_cpu(grant->wanted) & CEPH_CAP_ANY_FILE_WR)) {
-			/* re-request max_size if necessary */
-			ci->i_requested_max_size = 0;
-			wake = true;
-		}
+		if (ci->i_auth_cap == cap) {
+			if (ci->i_requested_max_size > max_size ||
+			    !(le32_to_cpu(grant->wanted) & CEPH_CAP_ANY_FILE_WR)) {
+				/* re-request max_size if necessary */
+				ci->i_requested_max_size = 0;
+				wake = true;
+			}
 
-		ceph_kick_flushing_inode_caps(session, ci);
-		spin_unlock(&ci->i_ceph_lock);
-		up_read(&session->s_mdsc->snap_rwsem);
+			ceph_kick_flushing_inode_caps(session, ci);
+			spin_unlock(&ci->i_ceph_lock);
+			up_read(&session->s_mdsc->snap_rwsem);
+		}
 	} else {
 		spin_unlock(&ci->i_ceph_lock);
 	}
-- 
2.34.1