Viewing: ext4-lookup-dotdot.patch
commit 113303973ec9f8484eb2355a1a6ef3c4c7fd6a56
Author: Alex Zhuravlev <alex@clusterfs.com>
AuthorDate: Sat Feb 10 06:33:41 2007 +0000
Subject: ext4: htree fix for '..' lookup
Avoid looping in directory lookup when ext3_dx_find_entry()
can't find the '..' entry in a directory and then looks it
up in the directory. This results in the ".." (parent
directory) entry being added as the child of a directory
in the dcache. The '..' lookup can happen knfsd is looking
up the path of a disconnected dentry.
Bugzilla-ID: b=10458
Signed-off-by: Alex Zhuravlev <alex@clusterfs.com>
Reviewed-by: Kalpak Shah <kalpak@clusterfs.com>
Signed-off-by: Andreas Dilger <adilger@clusterfs.com>
---
fs/ext4/namei.c | 28 +++++++++++++++++++++++++++-
1 file changed, 27 insertions(+), 1 deletion(-)
diff --git a/fs/ext4/namei.c b/fs/ext4/namei.c
index 4f0420b..a519200 100644
--- a/fs/ext4/namei.c
+++ b/fs/ext4/namei.c
@@ -1822,8 +1822,34 @@ static struct dentry *ext4_lookup(struct inode *dir, struct dentry *dentry, unsi
return ERR_PTR(-EPERM);
}
}
+ /* ".." shouldn't go into dcache to preserve dcache hierarchy
+ * otherwise we'll get parent being a child of actual child.
+ * see b=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 == NULL) {
+ 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;
+ }
-#if IS_ENABLED(CONFIG_UNICODE)
+#ifdef CONFIG_UNICODE
if (!inode && IS_CASEFOLDED(dir)) {
/* Eventually we want to call d_add_ci(dentry, NULL)
* for negative dentries in the encoding case as
--
2.34.1
