1 files changed, 18 insertions, 6 deletions

diff --git a/fs/libfs.c b/fs/libfs.c
index 433e7139c23..cc4794914b5 100644
--- a/fs/libfs.c
+++ b/fs/libfs.c
@@ -81,7 +81,8 @@ int dcache_dir_close(struct inode *inode, struct file *file)
 
 loff_t dcache_dir_lseek(struct file *file, loff_t offset, int origin)
 {
-	mutex_lock(&file->f_path.dentry->d_inode->i_mutex);
+	struct dentry *dentry = file->f_path.dentry;
+	mutex_lock(&dentry->d_inode->i_mutex);
 	switch (origin) {
 		case 1:
 			offset += file->f_pos;
@@ -89,7 +90,7 @@ loff_t dcache_dir_lseek(struct file *file, loff_t offset, int origin)
 			if (offset >= 0)
 				break;
 		default:
-			mutex_unlock(&file->f_path.dentry->d_inode->i_mutex);
+			mutex_unlock(&dentry->d_inode->i_mutex);
 			return -EINVAL;
 	}
 	if (offset != file->f_pos) {
@@ -100,22 +101,25 @@ loff_t dcache_dir_lseek(struct file *file, loff_t offset, int origin)
 			loff_t n = file->f_pos - 2;
 
 			spin_lock(&dcache_lock);
+			spin_lock(&dentry->d_lock);
+			/* d_lock not required for cursor */
 			list_del(&cursor->d_u.d_child);
-			p = file->f_path.dentry->d_subdirs.next;
-			while (n && p != &file->f_path.dentry->d_subdirs) {
+			p = dentry->d_subdirs.next;
+			while (n && p != &dentry->d_subdirs) {
 				struct dentry *next;
 				next = list_entry(p, struct dentry, d_u.d_child);
-				spin_lock(&next->d_lock);
+				spin_lock_nested(&next->d_lock, DENTRY_D_LOCK_NESTED);
 				if (simple_positive(next))
 					n--;
 				spin_unlock(&next->d_lock);
 				p = p->next;
 			}
 			list_add_tail(&cursor->d_u.d_child, p);
+			spin_unlock(&dentry->d_lock);
 			spin_unlock(&dcache_lock);
 		}
 	}
-	mutex_unlock(&file->f_path.dentry->d_inode->i_mutex);
+	mutex_unlock(&dentry->d_inode->i_mutex);
 	return offset;
 }
 
@@ -156,6 +160,7 @@ int dcache_readdir(struct file * filp, void * dirent, filldir_t filldir)
 			/* fallthrough */
 		default:
 			spin_lock(&dcache_lock);
+			spin_lock(&dentry->d_lock);
 			if (filp->f_pos == 2)
 				list_move(q, &dentry->d_subdirs);
 
@@ -169,6 +174,7 @@ int dcache_readdir(struct file * filp, void * dirent, filldir_t filldir)
 				}
 
 				spin_unlock(&next->d_lock);
+				spin_unlock(&dentry->d_lock);
 				spin_unlock(&dcache_lock);
 				if (filldir(dirent, next->d_name.name, 
 					    next->d_name.len, filp->f_pos, 
@@ -176,11 +182,15 @@ int dcache_readdir(struct file * filp, void * dirent, filldir_t filldir)
 					    dt_type(next->d_inode)) < 0)
 					return 0;
 				spin_lock(&dcache_lock);
+				spin_lock(&dentry->d_lock);
+				spin_lock_nested(&next->d_lock, DENTRY_D_LOCK_NESTED);
 				/* next is still alive */
 				list_move(q, p);
+				spin_unlock(&next->d_lock);
 				p = q;
 				filp->f_pos++;
 			}
+			spin_unlock(&dentry->d_lock);
 			spin_unlock(&dcache_lock);
 	}
 	return 0;
@@ -276,6 +286,7 @@ int simple_empty(struct dentry *dentry)
 	int ret = 0;
 
 	spin_lock(&dcache_lock);
+	spin_lock(&dentry->d_lock);
 	list_for_each_entry(child, &dentry->d_subdirs, d_u.d_child) {
 		spin_lock_nested(&child->d_lock, DENTRY_D_LOCK_NESTED);
 		if (simple_positive(child)) {
@@ -286,6 +297,7 @@ int simple_empty(struct dentry *dentry)
 	}
 	ret = 1;
 out:
+	spin_unlock(&dentry->d_lock);
 	spin_unlock(&dcache_lock);
 	return ret;
 }