linux-kernel - [PATCH 09/12] afs: Clear AFS_VNODE_CB_PROMISED if we detect callback expiry

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Date:   Wed, 15 May 2019 21:59:25 +0100
From:   David Howells <dhowells@...hat.com>
To:     linux-afs@...ts.infradead.org
Cc:     Marc Dionne <marc.dionne@...istor.com>, dhowells@...hat.com,
        linux-kernel@...r.kernel.org
Subject: [PATCH 09/12] afs: Clear AFS_VNODE_CB_PROMISED if we detect
 callback expiry

Fix afs_validate() to clear AFS_VNODE_CB_PROMISED on a vnode if we detect
any condition that causes the callback promise to be broken implicitly,
including server break (cb_s_break), volume break (cb_v_break) or callback
expiry.

Fixes: ae3b7361dc0e ("afs: Fix validation/callback interaction")
Reported-by: Marc Dionne <marc.dionne@...istor.com>
Signed-off-by: David Howells <dhowells@...hat.com>
---

 fs/afs/inode.c |   14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

diff --git a/fs/afs/inode.c b/fs/afs/inode.c
index 3633703dbc0c..866d3575c5de 100644
--- a/fs/afs/inode.c
+++ b/fs/afs/inode.c
@@ -570,7 +570,7 @@ bool afs_check_validity(struct afs_vnode *vnode)
 	struct afs_server *server;
 	struct afs_volume *volume = vnode->volume;
 	time64_t now = ktime_get_real_seconds();
-	bool valid;
+	bool valid, need_clear = false;
 	unsigned int cb_break, cb_s_break, cb_v_break;
 	int seq = 0;
 
@@ -588,10 +588,13 @@ bool afs_check_validity(struct afs_vnode *vnode)
 			    vnode->cb_v_break != cb_v_break) {
 				vnode->cb_s_break = cb_s_break;
 				vnode->cb_v_break = cb_v_break;
+				need_clear = true;
 				valid = false;
 			} else if (test_bit(AFS_VNODE_ZAP_DATA, &vnode->flags)) {
+				need_clear = true;
 				valid = false;
 			} else if (vnode->cb_expires_at - 10 <= now) {
+				need_clear = true;
 				valid = false;
 			} else {
 				valid = true;
@@ -606,6 +609,15 @@ bool afs_check_validity(struct afs_vnode *vnode)
 	} while (need_seqretry(&vnode->cb_lock, seq));
 
 	done_seqretry(&vnode->cb_lock, seq);
+
+	if (need_clear) {
+		write_seqlock(&vnode->cb_lock);
+		if (cb_break == vnode->cb_break)
+			__afs_break_callback(vnode);
+		write_sequnlock(&vnode->cb_lock);
+		valid = false;
+	}
+
 	return valid;
 }