On 14/11/2022 19:24, Jeff Layton wrote:

On Mon, 2022-11-14 at 13:19 +0800, xiubli@redhat.com wrote:

...

From: Xiubo Li xiubli@redhat.com

When ceph releasing the file_lock it will try to get the inode pointer from the fl->fl_file, which the memory could already be released by another thread in filp_close(). Because in VFS layer the fl->fl_file doesn't increase the file's reference counter.

Will switch to use ceph dedicate lock info to track the inode.

And in ceph_fl_release_lock() we should skip all the operations if the fl->fl_u.ceph_fl.fl_inode is not set, which should come from the request file_lock. And we will set fl->fl_u.ceph_fl.fl_inode when inserting it to the inode lock list, which is when copying the lock.

Cc: stable@vger.kernel.org URL: https://tracker.ceph.com/issues/57986 Signed-off-by: Xiubo Li xiubli@redhat.com

---

fs/ceph/locks.c | 18 +++++++++++++++--- include/linux/ceph/ceph_fs_fl.h | 26 ++++++++++++++++++++++++++ include/linux/fs.h | 2 ++ 3 files changed, 43 insertions(+), 3 deletions(-) create mode 100644 include/linux/ceph/ceph_fs_fl.h

diff --git a/fs/ceph/locks.c b/fs/ceph/locks.c index 3e2843e86e27..d8385dd0076e 100644 --- a/fs/ceph/locks.c +++ b/fs/ceph/locks.c @@ -34,22 +34,34 @@ static void ceph_fl_copy_lock(struct file_lock *dst, struct file_lock *src) { struct ceph_file_info *fi = dst->fl_file->private_data; struct inode *inode = file_inode(dst->fl_file);

• atomic_inc(&ceph_inode(inode)->i_filelock_ref); atomic_inc(&fi->num_locks);
• dst->fl_u.ceph_fl.fl_inode = igrab(inode); }

static void ceph_fl_release_lock(struct file_lock *fl) { struct ceph_file_info *fi = fl->fl_file->private_data;

• struct inode *inode = file_inode(fl->fl_file);
• struct ceph_inode_info *ci = ceph_inode(inode);
• atomic_dec(&fi->num_locks);

• struct inode *inode = fl->fl_u.ceph_fl.fl_inode;
• struct ceph_inode_info *ci;
• /*

• * If inode is NULL it should be a request file_lock,
  

• * nothing we can do.
  

• */
  

• if (!inode)

• return;
  

• ci = ceph_inode(inode); if (atomic_dec_and_test(&ci->i_filelock_ref)) { /* clear error when all locks are released */ spin_lock(&ci->i_ceph_lock); ci->i_ceph_flags &= ~CEPH_I_ERROR_FILELOCK; spin_unlock(&ci->i_ceph_lock); }
• iput(inode);
• atomic_dec(&fi->num_locks);

It doesn't look like this fixes the original issue. "fi" may be pointing to freed memory at this point, right?

Yeah, I didn't fix this in the this patch. I fixed it in a dedicated 2/2 patch.

I think you may need to get rid of the "num_locks" field in ceph_file_info, and do that in a different way?

This is a dedicated field for each 'file' struct. I have no idea how to fix this in a different way yet.

Thanks!

- Xiubo

...

} static const struct file_lock_operations ceph_fl_lock_ops = { diff --git a/include/linux/ceph/ceph_fs_fl.h b/include/linux/ceph/ceph_fs_fl.h new file mode 100644 index 000000000000..02a412b26095 --- /dev/null +++ b/include/linux/ceph/ceph_fs_fl.h @@ -0,0 +1,26 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/*

• • ceph_fs.h - Ceph constants and data types to share between kernel and
• • user space.
• • Most types in this file are defined as little-endian, and are
• • primarily intended to describe data structures that pass over the
• • wire or that are stored on disk.
• • LGPL2
• */

+#ifndef CEPH_FS_FL_H +#define CEPH_FS_FL_H

+#include <linux/fs.h>

+/*

• • Ceph lock info
• */

+struct ceph_lock_info {

• struct inode *fl_inode;

+};

+#endif diff --git a/include/linux/fs.h b/include/linux/fs.h index e654435f1651..db4810d19e26 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -1066,6 +1066,7 @@ bool opens_in_grace(struct net *); /* that will die - we need it for nfs_lock_info */ #include <linux/nfs_fs_i.h> +#include <linux/ceph/ceph_fs_fl.h> /*

• struct file_lock represents a generic "file lock". It's used to represent

@@ -1119,6 +1120,7 @@ struct file_lock { int state; /* state of grant or error if -ve */ unsigned int debug_id; } afs;

• struct ceph_lock_info	ceph_fl;
  

  } fl_u; } __randomize_layout;