smb3: fix unmount hang in open_shroot (96d9f7ed) · Commits · 戴 / test

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: ("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>

fs/cifs/smb2ops.c

+11 −10

Original line number	Diff line number	Diff line
		@@ -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);

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