Hi Greg, Are you going to apply this patch to the 5.3.y stable kernel? The patch is applicable there too.
Best regards, Pavel Shilovsky -----Original Message----- From: Greg Kroah-Hartman <[email protected]> Sent: Sunday, September 29, 2019 6:56 AM To: [email protected] Cc: Greg Kroah-Hartman <[email protected]>; [email protected]; kbuild test robot <[email protected]>; Dan Carpenter <[email protected]>; Pavel Shilovskiy <[email protected]>; Steven French <[email protected]>; Aurelien Aptel <[email protected]>; Sasha Levin <[email protected]> Subject: [PATCH 5.2 02/45] smb3: fix unmount hang in open_shroot From: Steve French <[email protected]> [ Upstream commit 96d9f7ed00b86104bf03adeffc8980897e9694ab ] 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 <[email protected]> Reported-by: Dan Carpenter <[email protected]> Suggested-by: Pavel Shilovsky <[email protected]> Reviewed-by: Pavel Shilovsky <[email protected]> Signed-off-by: Steve French <[email protected]> CC: Aurelien Aptel <[email protected]> CC: Stable <[email protected]> Signed-off-by: Sasha Levin <[email protected]> --- 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 42de31d206169..8ae8ef526b4a5 100644 --- a/fs/cifs/smb2ops.c +++ b/fs/cifs/smb2ops.c @@ -656,6 +656,15 @@ 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; @@ -677,7 +686,7 @@ 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)); @@ -690,18 +699,10 @@ 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
