[PATCH 1/3] autofs4 - fix get_next_positive_dentry()

Ian Kent
2011-01-18T04:15:34Z

The initialization condition in fs/autofs4/expire.c:get_next_positive_dentry()
appears to be incorrect. If prev == NULL I believe that root should be
returned.

Further down, at the current dentry check for it being simple_positive()
it looks like the d_lock for dentry p should be dropped instead of dentry
ret, otherwise when p is assinged to ret we end up with no lock on p and
a lost lock on ret, which leads to a deadlock.
---

fs/autofs4/expire.c | 4 ++--
1 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/fs/autofs4/expire.c b/fs/autofs4/expire.c
index 3ed79d7..f43100b 100644
--- a/fs/autofs4/expire.c
+++ b/fs/autofs4/expire.c
@@ -96,7 +96,7 @@ static struct dentry *get_next_positive_dentry(struct dentry *prev,
struct dentry *p, *ret;

if (prev == NULL)
- return dget(prev);
+ return dget(root);

spin_lock(&autofs4_lock);
relock:
@@ -133,7 +133,7 @@ again:
spin_lock_nested(&ret->d_lock, DENTRY_D_LOCK_NESTED);
/* Negative dentry - try next */
if (!simple_positive(ret)) {
- spin_unlock(&ret->d_lock);
+ spin_unlock(&p->d_lock);
p = ret;
goto again;
}