From 34d8dc26eb1f37040b4819e65dfde4017ae3a281 Mon Sep 17 00:00:00 2001 From: Steve French Date: Thu, 12 Sep 2019 17:52:54 -0500 Subject: [PATCH] smb3: fix unmount hang in open_shroot 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 Reported-by: Dan Carpenter Suggested-by: Pavel Shilovsky Reviewed-by: Pavel Shilovsky Signed-off-by: Steve French CC: Aurelien Aptel CC: Stable --- 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); -- 2.20.1