From: Steve French <stfrench@microsoft.com>
Date: Thu, 12 Sep 2019 17:52:54 -0500
Subject: smb3: fix unmount hang in open_shroot
Git-commit: 96d9f7ed00b86104bf03adeffc8980897e9694ab
Patch-mainline: 5.4-rc1
References: bnc#1151927 5.3.4
An earlier patch "CIFS: fix deadlock in cached root handling"
did not completely address the deadlock in open_shroot. This
patch addresses the deadlock.
In testing the recent patch:
smb3: improve handling of share deleted (and share recreated)
we were able to reproduce the open_shroot deadlock to one
of the target servers in unmount in a delete share scenario.
Fixes: 7e5a70ad88b1e ("CIFS: fix deadlock in cached root handling")
This is version 2 of this patch. An earlier version of this
patch "smb3: fix unmount hang in open_shroot" had a problem
found by Dan.
Reported-by: kbuild test robot <lkp@intel.com>
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Suggested-by: Pavel Shilovsky <pshilov@microsoft.com>
Reviewed-by: Pavel Shilovsky <pshilov@microsoft.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
CC: Aurelien Aptel <aaptel@suse.com>
CC: Stable <stable@vger.kernel.org>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
---
fs/cifs/smb2ops.c | 21 +++++++++++----------
1 file changed, 11 insertions(+), 10 deletions(-)
diff --git a/fs/cifs/smb2ops.c b/fs/cifs/smb2ops.c
index 3672ce0bfbaf..5776d7b0a97e 100644
--- a/fs/cifs/smb2ops.c
+++ b/fs/cifs/smb2ops.c
@@ -658,6 +658,15 @@ int open_shroot(unsigned int xid, struct cifs_tcon *tcon, struct cifs_fid *pfid)
return 0;
}
+ /*
+ * We do not hold the lock for the open because in case
+ * SMB2_open needs to reconnect, it will end up calling
+ * cifs_mark_open_files_invalid() which takes the lock again
+ * thus causing a deadlock
+ */
+
+ mutex_unlock(&tcon->crfid.fid_mutex);
+
if (smb3_encryption_required(tcon))
flags |= CIFS_TRANSFORM_REQ;
@@ -679,7 +688,7 @@ int open_shroot(unsigned int xid, struct cifs_tcon *tcon, struct cifs_fid *pfid)
rc = SMB2_open_init(tcon, &rqst[0], &oplock, &oparms, &utf16_path);
if (rc)
- goto oshr_exit;
+ goto oshr_free;
smb2_set_next_command(tcon, &rqst[0]);
memset(&qi_iov, 0, sizeof(qi_iov));
@@ -692,18 +701,10 @@ int open_shroot(unsigned int xid, struct cifs_tcon *tcon, struct cifs_fid *pfid)
sizeof(struct smb2_file_all_info) +
PATH_MAX * 2, 0, NULL);
if (rc)
- goto oshr_exit;
+ goto oshr_free;
smb2_set_related(&rqst[1]);
- /*
- * We do not hold the lock for the open because in case
- * SMB2_open needs to reconnect, it will end up calling
- * cifs_mark_open_files_invalid() which takes the lock again
- * thus causing a deadlock
- */
-
- mutex_unlock(&tcon->crfid.fid_mutex);
rc = compound_send_recv(xid, ses, flags, 2, rqst,
resp_buftype, rsp_iov);
mutex_lock(&tcon->crfid.fid_mutex);
--
2.33.1