[lustre-devel] [PATCH 02/22] ext4: use d_find_alias() in ext4_lookup

[James Simmons <jsimmons@infradead.org>]

From: James Simmons <uja.ornl@yahoo.com>

Really old bug that might not even exist anymore?

Signed-off-by: James Simmons <jsimmons@infradead.org>
---
 fs/ext4/namei.c | 29 +++++++++++++++++++++++++++++
 1 file changed, 29 insertions(+)

diff --git a/fs/ext4/namei.c b/fs/ext4/namei.c
index cd01c4a..a616f58 100644
--- a/fs/ext4/namei.c
+++ b/fs/ext4/namei.c
@@ -1664,6 +1664,35 @@ static struct dentry *ext4_lookup(struct inode *dir, struct dentry *dentry, unsi
 		}
 	}
 
+	/* ".." shouldn't go into dcache to preserve dcache hierarchy
+	 * otherwise we'll get parent being a child of actual child.
+	 * see bug 10458 for details -bzzz
+	 */
+	if (inode && (dentry->d_name.name[0] == '.' &&
+		      (dentry->d_name.len == 1 || (dentry->d_name.len == 2 &&
+						   dentry->d_name.name[1] == '.')))) {
+		struct dentry *goal = NULL;
+
+		/* first, look for an existing dentry - any one is good */
+		goal = d_find_any_alias(inode);
+		if (!goal) {
+			spin_lock(&dentry->d_lock);
+			/* there is no alias, we need to make current dentry:
+			 *  a) inaccessible for __d_lookup()
+			 *  b) inaccessible for iopen
+			 */
+			J_ASSERT(hlist_unhashed(&dentry->d_u.d_alias));
+			dentry->d_flags |= DCACHE_NFSFS_RENAMED;
+			/* this is d_instantiate() ... */
+			hlist_add_head(&dentry->d_u.d_alias, &inode->i_dentry);
+			dentry->d_inode = inode;
+			spin_unlock(&dentry->d_lock);
+		}
+		if (goal)
+			iput(inode);
+		return goal;
+	}
+
 #ifdef CONFIG_UNICODE
 	if (!inode && IS_CASEFOLDED(dir)) {
 		/* Eventually we want to call d_add_ci(dentry, NULL)
-- 
1.8.3.1