Linux: osi_TryEvictVCache: Don’t skip the first dentry if D_ALIAS_IS_HLIST
authorAnders Kaseorg <andersk@mit.edu>
Tue, 7 May 2013 04:27:33 +0000 (00:27 -0400)
committerJeffrey Altman <jaltman@your-file-system.com>
Sat, 11 May 2013 15:43:32 +0000 (08:43 -0700)
An hlist doesn’t begin with a sentinel like a list does, so the old
code would skip the first dentry or crash with a NULL dereference if
there wasn’t one.  Use the kernel’s list_for_each_entry or
hlist_for_each_entry macros instead of trying to do it manually.

Should fix a crash observed by Alex Chernyakhovsky on kernel 3.6 and
newer.

Change-Id: I6d7bd190013a0250ca896af8d5182df55a3376b0
Signed-off-by: Anders Kaseorg <andersk@mit.edu>
Reviewed-on: http://gerrit.openafs.org/9857
Reviewed-by: Alex Chernyakhovsky <achernya@mit.edu>
Tested-by: Alex Chernyakhovsky <achernya@mit.edu>
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Marc Dionne <marc.c.dionne@gmail.com>
Reviewed-by: Jeffrey Altman <jaltman@your-file-system.com>

src/afs/LINUX/osi_vcache.c

index dc3685b..99aab91 100644 (file)
@@ -19,10 +19,8 @@ osi_TryEvictVCache(struct vcache *avc, int *slept, int defersleep) {
 
     struct dentry *dentry;
     struct inode *inode = AFSTOV(avc);
-#if defined(D_ALIAS_IS_HLIST)
-    struct hlist_node *cur, *head, *list_end;
-#else
-    struct list_head *cur, *head, *list_end;
+#if defined(D_ALIAS_IS_HLIST) && !defined(HLIST_ITERATOR_NO_NODE)
+    struct hlist_node *p;
 #endif
 
     /* First, see if we can evict the inode from the dcache */
@@ -33,13 +31,9 @@ osi_TryEvictVCache(struct vcache *avc, int *slept, int defersleep) {
 
 #if defined(HAVE_DCACHE_LOCK)
         spin_lock(&dcache_lock);
-       head = &inode->i_dentry;
 
 restart:
-        cur = head;
-       while ((cur = cur->next) != head) {
-           dentry = list_entry(cur, struct dentry, d_alias);
-
+       list_for_each_entry(dentry, &inode->i_dentry, d_alias) {
            if (d_unhashed(dentry))
                continue;
            dget_locked(dentry);
@@ -57,23 +51,17 @@ restart:
        spin_unlock(&dcache_lock);
 #else /* HAVE_DCACHE_LOCK */
        spin_lock(&inode->i_lock);
-#if defined(D_ALIAS_IS_HLIST)
-       head = inode->i_dentry.first;
-       list_end = NULL;
-#else
-       head = &inode->i_dentry;
-       list_end = head;
-#endif
 
 restart:
-       cur = head;
-       while ((cur = cur->next) != list_end) {
 #if defined(D_ALIAS_IS_HLIST)
-           dentry = hlist_entry(cur, struct dentry, d_alias);
+# if defined(HLIST_ITERATOR_NO_NODE)
+       hlist_for_each_entry(dentry, &inode->i_dentry, d_alias) {
+# else
+       hlist_for_each_entry(dentry, p, &inode->i_dentry, d_alias) {
+# endif
 #else
-           dentry = list_entry(cur, struct dentry, d_alias);
+       list_for_each_entry(dentry, &inode->i_dentry, d_alias) {
 #endif
-
            spin_lock(&dentry->d_lock);
            if (d_unhashed(dentry)) {
                spin_unlock(&dentry->d_lock);