Merge branch 'upstream-linus' of master.kernel.org:/pub/scm/linux/kernel/git/jgarzik...

[powerpc.git] / fs / inode.c

diff --git a/fs/inode.c b/fs/inode.c
index bf6bec4..26cdb11 100644 (file)
--- a/fs/inode.c
+++ b/fs/inode.c
@@ -162,7 +162,7 @@ static struct inode *alloc_inode(struct super_block *sb)
                                bdi = sb->s_bdev->bd_inode->i_mapping->backing_dev_info;
                        mapping->backing_dev_info = bdi;
                }
-               inode->i_private = 0;
+               inode->i_private = NULL;
                inode->i_mapping = mapping;
        }
        return inode;
@@ -1306,6 +1306,42 @@ void wake_up_inode(struct inode *inode)
        wake_up_bit(&inode->i_state, __I_LOCK);
 }
 
+/*
+ * We rarely want to lock two inodes that do not have a parent/child
+ * relationship (such as directory, child inode) simultaneously. The
+ * vast majority of file systems should be able to get along fine
+ * without this. Do not use these functions except as a last resort.
+ */
+void inode_double_lock(struct inode *inode1, struct inode *inode2)
+{
+       if (inode1 == NULL || inode2 == NULL || inode1 == inode2) {
+               if (inode1)
+                       mutex_lock(&inode1->i_mutex);
+               else if (inode2)
+                       mutex_lock(&inode2->i_mutex);
+               return;
+       }
+
+       if (inode1 < inode2) {
+               mutex_lock_nested(&inode1->i_mutex, I_MUTEX_PARENT);
+               mutex_lock_nested(&inode2->i_mutex, I_MUTEX_CHILD);
+       } else {
+               mutex_lock_nested(&inode2->i_mutex, I_MUTEX_PARENT);
+               mutex_lock_nested(&inode1->i_mutex, I_MUTEX_CHILD);
+       }
+}
+EXPORT_SYMBOL(inode_double_lock);
+
+void inode_double_unlock(struct inode *inode1, struct inode *inode2)
+{
+       if (inode1)
+               mutex_unlock(&inode1->i_mutex);
+
+       if (inode2 && inode2 != inode1)
+               mutex_unlock(&inode2->i_mutex);
+}
+EXPORT_SYMBOL(inode_double_unlock);
+
 static __initdata unsigned long ihash_entries;
 static int __init set_ihash_entries(char *str)
 {