linux-kernel - [PATCH 4/4] cachefiles: Wait rather than BUG'ing on "Unexpected object collision"

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Message-ID: <153080829041.5496.6336874857121191833.stgit@warthog.procyon.org.uk>
Date:   Thu, 05 Jul 2018 17:31:30 +0100
From:   David Howells <dhowells@...hat.com>
To:     linux-cachefs@...hat.com
Cc:     kiran.modukuri@...il.com, carmark.dlut@...il.com,
        vegard.nossum@...il.com, linux-kernel@...r.kernel.org,
        neilb@...e.com, aderobertis@...rics.net, dhowells@...hat.com,
        dja@...ens.net
Subject: [PATCH 4/4] cachefiles: Wait rather than BUG'ing on "Unexpected
 object collision"

From: Kiran Kumar Modukuri <kiran.modukuri@...il.com>

If we meet a conflicting object that is marked FSCACHE_OBJECT_IS_LIVE in
the active object tree, we have been emitting a BUG after logging
information about it and the new object.

Instead, we should wait for the CACHEFILES_OBJECT_ACTIVE flag to be cleared
on the old object (or return an error).  The ACTIVE flag should be cleared
after it has been removed from the active object tree.  A timeout of 60s is
used in the wait, so we shouldn't be able to get stuck there.

Signed-off-by: Kiran Kumar Modukuri <kiran.modukuri@...il.com>
Signed-off-by: David Howells <dhowells@...hat.com>
---

 fs/cachefiles/namei.c |    1 -
 1 file changed, 1 deletion(-)

diff --git a/fs/cachefiles/namei.c b/fs/cachefiles/namei.c
index b5d6dd72dfa0..af2b17b21b94 100644
--- a/fs/cachefiles/namei.c
+++ b/fs/cachefiles/namei.c
@@ -192,7 +192,6 @@ static int cachefiles_mark_object_active(struct cachefiles_cache *cache,
 		pr_err("\n");
 		pr_err("Error: Unexpected object collision\n");
 		cachefiles_printk_object(object, xobject);
-		BUG();
 	}
 	atomic_inc(&xobject->usage);
 	write_unlock(&cache->active_lock);