[PATCH] lockdep: annotate i_mutex

Teach special (recursive) locking code to the lock validator.  Has no effect
on non-lockdep kernels.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

3 files changed, 30 insertions, 11 deletions

diff --git a/drivers/usb/core/inode.c b/drivers/usb/core/inode.c
index e47e3a8ed6e4..cf11196e012d 100644
--- a/drivers/usb/core/inode.c
+++ b/drivers/usb/core/inode.c
@@ -200,7 +200,7 @@ static void update_sb(struct super_block *sb)
         if (!root)
                 return;
 
-        mutex_lock(&root->d_inode->i_mutex);
+        mutex_lock_nested(&root->d_inode->i_mutex, I_MUTEX_PARENT);
 
         list_for_each_entry(bus, &root->d_subdirs, d_u.d_child) {
                 if (bus->d_inode) {
diff --git a/fs/namei.c b/fs/namei.c
index c784e8bb57a3..c9750d755aff 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -1423,7 +1423,7 @@ struct dentry *lock_rename(struct dentry *p1, struct dentry *p2)
         struct dentry *p;
 
         if (p1 == p2) {
-                mutex_lock(&p1->d_inode->i_mutex);
+                mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT);
                 return NULL;
         }
 
@@ -1431,22 +1431,22 @@ struct dentry *lock_rename(struct dentry *p1, struct dentry *p2)
 
         for (p = p1; p->d_parent != p; p = p->d_parent) {
                 if (p->d_parent == p2) {
-                        mutex_lock(&p2->d_inode->i_mutex);
-                        mutex_lock(&p1->d_inode->i_mutex);
+                        mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_PARENT);
+                        mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_CHILD);
                         return p;
                 }
         }
 
         for (p = p2; p->d_parent != p; p = p->d_parent) {
                 if (p->d_parent == p1) {
-                        mutex_lock(&p1->d_inode->i_mutex);
-                        mutex_lock(&p2->d_inode->i_mutex);
+                        mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT);
+                        mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD);
                         return p;
                 }
         }
 
-        mutex_lock(&p1->d_inode->i_mutex);
-        mutex_lock(&p2->d_inode->i_mutex);
+        mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT);
+        mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD);
         return NULL;
 }
 
@@ -1751,7 +1751,7 @@ struct dentry *lookup_create(struct nameidata *nd, int is_dir)
 {
         struct dentry *dentry = ERR_PTR(-EEXIST);
 
-        mutex_lock(&nd->dentry->d_inode->i_mutex);
+        mutex_lock_nested(&nd->dentry->d_inode->i_mutex, I_MUTEX_PARENT);
         /*
          * Yucky last component or no last component at all?
          * (foo/., foo/.., /////)
@@ -2008,7 +2008,7 @@ static long do_rmdir(int dfd, const char __user *pathname)
                         error = -EBUSY;
                         goto exit1;
         }
-        mutex_lock(&nd.dentry->d_inode->i_mutex);
+        mutex_lock_nested(&nd.dentry->d_inode->i_mutex, I_MUTEX_PARENT);
         dentry = lookup_hash(&nd);
         error = PTR_ERR(dentry);
         if (!IS_ERR(dentry)) {
@@ -2082,7 +2082,7 @@ static long do_unlinkat(int dfd, const char __user *pathname)
         error = -EISDIR;
         if (nd.last_type != LAST_NORM)
                 goto exit1;
-        mutex_lock(&nd.dentry->d_inode->i_mutex);
+        mutex_lock_nested(&nd.dentry->d_inode->i_mutex, I_MUTEX_PARENT);
         dentry = lookup_hash(&nd);
         error = PTR_ERR(dentry);
         if (!IS_ERR(dentry)) {
diff --git a/include/linux/fs.h b/include/linux/fs.h
index e04a5cfe874f..05ded9e76b23 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -543,6 +543,25 @@ struct inode {
 };
 
 /*
+ * inode->i_mutex nesting subclasses for the lock validator:
+ *
+ * 0: the object of the current VFS operation
+ * 1: parent
+ * 2: child/target
+ * 3: quota file
+ *
+ * The locking order between these classes is
+ * parent -> child -> normal -> quota
+ */
+enum inode_i_mutex_lock_class
+{
+        I_MUTEX_NORMAL,
+        I_MUTEX_PARENT,
+        I_MUTEX_CHILD,
+        I_MUTEX_QUOTA
+};
+
+/*
  * NOTE: in a 32bit arch with a preemptable kernel and
  * an UP compile the i_size_read/write must be atomic
  * with respect to the local cpu (unlike with preempt disabled),