[PATCH 5.10 371/406] fuse: nlookup missing decrement in fuse_direntplus_link

Greg Kroah-Hartman
2023-09-17T19:41:16Z

From: ruanmeisi <ruan.meisi@zte.com.cn>

commit b8bd342d50cbf606666488488f9fea374aceb2d5 upstream.

During our debugging of glusterfs, we found an Assertion failed error:
inode_lookup >= nlookup, which was caused by the nlookup value in the
kernel being greater than that in the FUSE file system.

The issue was introduced by fuse_direntplus_link, where in the function,
fuse_iget increments nlookup, and if d_splice_alias returns failure,
fuse_direntplus_link returns failure without decrementing nlookup
https://github.com/gluster/glusterfs/pull/4081

Signed-off-by: ruanmeisi <ruan.meisi@zte.com.cn>
Fixes: 0b05b18381ee ("fuse: implement NFS-like readdirplus support")
Cc: <stable@vger.kernel.org> # v3.9
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
fs/fuse/readdir.c | 10 +++++++++-
1 file changed, 9 insertions(+), 1 deletion(-)

--- a/fs/fuse/readdir.c
+++ b/fs/fuse/readdir.c
@@ -243,8 +243,16 @@ retry:
dput(dentry);
dentry = alias;
}
- if (IS_ERR(dentry))
+ if (IS_ERR(dentry)) {
+ if (!IS_ERR(inode)) {
+ struct fuse_inode *fi = get_fuse_inode(inode);
+
+ spin_lock(&fi->lock);
+ fi->nlookup--;
+ spin_unlock(&fi->lock);
+ }
return PTR_ERR(dentry);
+ }
}
if (fc->readdirplus_auto)
set_bit(FUSE_I_INIT_RDPLUS, &get_fuse_inode(inode)->state);