From: Eric Biggers <ebiggers@xxxxxxxxxx>
We can reach 'out:' with a negative dentry, e.g. if there is contention
on ->d_parent->d_lock and another task concurrently gets a reference to
the negative dentry. In that case 'inode' will be NULL, so we must not
try to unlock 'inode'.
This bug was found by xfstest generic/429.
Fixes: 121a8e083486 ("get rid of trylock loop in locking dentries on shrink list")
Signed-off-by: Eric Biggers <ebiggers@xxxxxxxxxx>
---
fs/dcache.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/fs/dcache.c b/fs/dcache.c
index 0c78ef4bb5e7..c159a4b304cf 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -1028,7 +1028,8 @@ static bool shrink_lock_dentry(struct dentry *dentry)
return true;
spin_unlock(&parent->d_lock);
out:
- spin_unlock(&inode->i_lock);
+ if (inode)
+ spin_unlock(&inode->i_lock);
return false;
}
--
2.17.0.rc0.231.g781580f067-goog
