From d70b67c8bc72ee23b55381bd6a884f4796692f77 Mon Sep 17 00:00:00 2001 From: Miklos Szeredi Date: Wed, 2 Jul 2008 21:30:15 +0200 Subject: [PATCH] [patch] vfs: fix lookup on deleted directory Lookup can install a child dentry for a deleted directory. This keeps the directory dentry alive, and the inode pinned in the cache and on disk, even after all external references have gone away. This isn't a big problem normally, since memory pressure or umount will clear out the directory dentry and its children, releasing the inode. But for UBIFS this causes problems because its orphan area can overflow. Fix this by returning ENOENT for all lookups on a S_DEAD directory before creating a child dentry. Thanks to Zoltan Sogor for noticing this while testing UBIFS, and Artem for the excellent analysis of the problem and testing. Reported-by: Artem Bityutskiy Tested-by: Artem Bityutskiy Signed-off-by: Miklos Szeredi Signed-off-by: Al Viro --- fs/namei.c | 19 +++++++++++++++++-- 1 file changed, 17 insertions(+), 2 deletions(-) diff --git a/fs/namei.c b/fs/namei.c index 01e67dddcc3d..3b26a240ade9 100644 --- a/fs/namei.c +++ b/fs/namei.c @@ -519,7 +519,14 @@ static struct dentry * real_lookup(struct dentry * parent, struct qstr * name, s */ result = d_lookup(parent, name); if (!result) { - struct dentry * dentry = d_alloc(parent, name); + struct dentry *dentry; + + /* Don't create child dentry for a dead directory. */ + result = ERR_PTR(-ENOENT); + if (IS_DEADDIR(dir)) + goto out_unlock; + + dentry = d_alloc(parent, name); result = ERR_PTR(-ENOMEM); if (dentry) { result = dir->i_op->lookup(dir, dentry, nd); @@ -528,6 +535,7 @@ static struct dentry * real_lookup(struct dentry * parent, struct qstr * name, s else result = dentry; } +out_unlock: mutex_unlock(&dir->i_mutex); return result; } @@ -1317,7 +1325,14 @@ static struct dentry *__lookup_hash(struct qstr *name, dentry = cached_lookup(base, name, nd); if (!dentry) { - struct dentry *new = d_alloc(base, name); + struct dentry *new; + + /* Don't create child dentry for a dead directory. */ + dentry = ERR_PTR(-ENOENT); + if (IS_DEADDIR(inode)) + goto out; + + new = d_alloc(base, name); dentry = ERR_PTR(-ENOMEM); if (!new) goto out; -- 2.20.1