source: branches/fc15-dev/server/common/patches/openafs-0007-Linux-2.6.38-deal-with-dcache_lock-removal.patch @ 1902

From 2c3b79c8c242d12398eff647753370787b7cf300 Mon Sep 17 00:00:00 2001
From: Marc Dionne <marc.c.dionne@gmail.com>
Date: Fri, 28 Jan 2011 20:59:17 -0500
Subject: [PATCH 7/8] Linux: 2.6.38: deal with dcache_lock removal

dcache_lock is gone in 2.6.38, and some of the vfs locking rules
have changed.

Of interest for openafs:
- inode->i_lock protects the d_alias list
- dentry->d_lock protects d_unhashed()

Add a new configure test for dcache_lock, and replace its use by
the appropriate new lock(s).

Reviewed-on: http://gerrit.openafs.org/3771
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Derrick Brashear <shadow@dementia.org>
(cherry picked from commit 2eca7aef7b2940e4ef5f9901ce28481af6edb6dd)

Change-Id: Ie405bb1e40cca4ba83bca3e051e2ab54b8850ac6
Signed-off-by: Anders Kaseorg <andersk@mit.edu>
Reviewed-on: http://gerrit.openafs.org/3998
Reviewed-by: Simon Wilkinson <sxw@inf.ed.ac.uk>
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Marc Dionne <marc.c.dionne@gmail.com>
Reviewed-by: Russ Allbery <rra@stanford.edu>
Reviewed-on: http://gerrit.openafs.org/4043
Reviewed-by: Derrick Brashear <shadow@dementia.org>
Tested-by: Derrick Brashear <shadow@dementia.org>
---
 acinclude.m4          |    1 +
 src/afs/afs_daemons.c |    8 ++++++++
 src/afs/afs_vcache.c  |   35 +++++++++++++++++++++++++++++++++--
 src/cf/linux-test4.m4 |   11 +++++++++++
 4 files changed, 53 insertions(+), 2 deletions(-)

diff --git a/acinclude.m4 b/acinclude.m4
index 7904e20..655fb11 100644
--- a/acinclude.m4
+++ b/acinclude.m4
@@ -817,6 +817,7 @@ case $AFS_SYSNAME in *_linux* | *_umlinux*)
                 LINUX_GENERIC_FILE_AIO_READ
                 LINUX_INIT_WORK_HAS_DATA
                 LINUX_REGISTER_SYSCTL_TABLE_NOFLAG
+                LINUX_HAVE_DCACHE_LOCK
                 LINUX_SYSCTL_TABLE_CHECKING
                 LINUX_STRUCT_CTL_TABLE_HAS_CTL_NAME
                 LINUX_HAVE_IGET
diff --git a/src/afs/afs_daemons.c b/src/afs/afs_daemons.c
index bd5bba8..3d9d977 100644
--- a/src/afs/afs_daemons.c
+++ b/src/afs/afs_daemons.c
@@ -376,7 +376,11 @@ afs_CheckRootVolume(void)
                    dp = d_find_alias(AFSTOV(afs_globalVp));
                    
 #if defined(AFS_LINUX24_ENV)
+#if defined(HAVE_DCACHE_LOCK)
                    spin_lock(&dcache_lock);
+#else
+                   spin_lock(&AFSTOV(vcp)->i_lock);
+#endif
 #if defined(AFS_LINUX26_ENV)
                    spin_lock(&dp->d_lock);
 #endif
@@ -388,7 +392,11 @@ afs_CheckRootVolume(void)
 #if defined(AFS_LINUX26_ENV)
                    spin_unlock(&dp->d_lock);
 #endif
+#if defined(HAVE_DCACHE_LOCK)
                    spin_unlock(&dcache_lock);
+#else
+                   spin_unlock(&AFSTOV(vcp)->i_lock);
+#endif
 #endif
                    dput(dp);
                    
diff --git a/src/afs/afs_vcache.c b/src/afs/afs_vcache.c
index 201bae7..63e6a27 100644
--- a/src/afs/afs_vcache.c
+++ b/src/afs/afs_vcache.c
@@ -673,12 +673,15 @@ afs_ShakeLooseVCaches(afs_int32 anumber)
 #if defined(AFS_LINUX22_ENV)
            if (tvc != afs_globalVp && VREFCOUNT(tvc) > 1 && tvc->opens == 0) {
                 struct dentry *dentry;
+               struct inode *inode = AFSTOV(tvc);
                 struct list_head *cur, *head;
                 AFS_GUNLOCK();
+
+#if defined(HAVE_DCACHE_LOCK)
 #if defined(AFS_LINUX24_ENV)
                 spin_lock(&dcache_lock);
 #endif
-               head = &(AFSTOV(tvc))->i_dentry;
+               head = &inode->i_dentry;
 
 restart:
                 cur = head;
@@ -687,7 +690,6 @@ restart:
 
                    if (d_unhashed(dentry))
                        continue;
-
                    dget_locked(dentry);
 
 #if defined(AFS_LINUX24_ENV)
@@ -707,6 +709,35 @@ restart:
 #if defined(AFS_LINUX24_ENV)
                spin_unlock(&dcache_lock);
 #endif
+#else /* HAVE_DCACHE_LOCK */
+               spin_lock(&inode->i_lock);
+               head = &inode->i_dentry;
+
+restart:
+               cur = head;
+               while ((cur = cur->next) != head) {
+                   dentry = list_entry(cur, struct dentry, d_alias);
+
+                   spin_lock(&dentry->d_lock);
+                   if (d_unhashed(dentry)) {
+                       spin_unlock(&dentry->d_lock);
+                       continue;
+                   }
+                   spin_unlock(&dentry->d_lock);
+                   dget(dentry);
+
+                   spin_unlock(&inode->i_lock);
+                   if (d_invalidate(dentry) == -EBUSY) {
+                       dput(dentry);
+                       /* perhaps lock and try to continue? (use cur as head?) */
+                       goto inuse;
+                   }
+                   dput(dentry);
+                   spin_lock(&inode->i_lock);
+                   goto restart;
+               }
+               spin_unlock(&inode->i_lock);
+#endif /* HAVE_DCACHE_LOCK */
            inuse:
                AFS_GLOCK();
            }
diff --git a/src/cf/linux-test4.m4 b/src/cf/linux-test4.m4
index 88e4863..2f426ce 100644
--- a/src/cf/linux-test4.m4
+++ b/src/cf/linux-test4.m4
@@ -1316,3 +1316,14 @@ AC_DEFUN([LINUX_HAVE_INODE_SETATTR], [
   if test "x$ac_cv_linux_inode_setattr" = "xyes"; then
     AC_DEFINE([HAVE_LINUX_INODE_SETATTR], 1, [define if your kernel has inode_setattr()])
   fi])
+
+AC_DEFUN([LINUX_HAVE_DCACHE_LOCK], [
+  AC_CHECK_LINUX_BUILD([for dcache_lock],
+                       [ac_cv_linux_have_dcache_lock],
+                       [#include <linux/dcache.h> ],
+                       [printk("%p", &dcache_lock);],
+                       [HAVE_DCACHE_LOCK],
+                       [define if dcache_lock exists],
+                       [])
+])
+
-- 
1.7.3.4