From: Michael Meffie <mmeffie@sinenomine.net>
Date: Thu, 25 Feb 2016 23:49:20 +0000 (-0500)
Subject: LINUX: hold vcache while dropping dcache refs
X-Git-Tag: upstream/1.6.18^2~4
X-Git-Url: https://git.michaelhowe.org/gitweb/?a=commitdiff_plain;h=440b518e6045e7cf2cd587dde38d95a29886aee3;p=packages%2Fo%2Fopenafs.git

LINUX: hold vcache while dropping dcache refs

Hold a reference on a vcache while attempting to evict the inode from
the dcache. Since the afs_xvcache lock is dropped, it could be possible
for the vcache to be flushed during this time, making it unsafe to use
the vcache after the eviction attempt.

Reviewed-on: https://gerrit.openafs.org/12206
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Andrew Deason <adeason@dson.org>
Reviewed-by: Benjamin Kaduk <kaduk@mit.edu>
(cherry picked from commit 961875cbedc2c91cdba6dc34a43c6136ea9797fb)

Change-Id: I5beea5798f6cb10a00db90e1ba18dbc7ab1e43cb
Reviewed-on: https://gerrit.openafs.org/12256
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Stephan Wiesand <stephan.wiesand@desy.de>
---

diff --git a/src/afs/LINUX/osi_vcache.c b/src/afs/LINUX/osi_vcache.c
index e64265f76..8a0c57899 100644
--- a/src/afs/LINUX/osi_vcache.c
+++ b/src/afs/LINUX/osi_vcache.c
@@ -28,6 +28,7 @@ osi_TryEvictVCache(struct vcache *avc, int *slept, int defersleep) {
     /* First, see if we can evict the inode from the dcache */
     if (defersleep && avc != afs_globalVp && VREFCOUNT(avc) > 1 && avc->opens == 0) {
 	*slept = 1;
+	AFS_FAST_HOLD(avc);
 	ReleaseWriteLock(&afs_xvcache);
         AFS_GUNLOCK();
 
@@ -87,6 +88,7 @@ restart:
 inuse:
 	AFS_GLOCK();
 	ObtainWriteLock(&afs_xvcache, 733);
+	AFS_FAST_RELE(avc);
     }
 
     /* See if we can evict it from the VLRUQ */