From: Steve French stfrench@microsoft.com
commit 96d9f7ed00b86104bf03adeffc8980897e9694ab upstream.
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: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- fs/cifs/smb2ops.c | 21 +++++++++++---------- 1 file changed, 11 insertions(+), 10 deletions(-)
--- a/fs/cifs/smb2ops.c +++ b/fs/cifs/smb2ops.c @@ -656,6 +656,15 @@ int open_shroot(unsigned int xid, struct 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;
@@ -677,7 +686,7 @@ int open_shroot(unsigned int xid, struct
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)); @@ -690,18 +699,10 @@ int open_shroot(unsigned int xid, struct 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);