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cifs: prevent data race in cifs_reconnect_tcon()

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Make sure to get an up-to-date TCP_Server_Info::nr_targets value prior
to waiting the server to be reconnected in cifs_reconnect_tcon().  It
is set in cifs_tcp_ses_needs_reconnect() and protected by
TCP_Server_Info::srv_lock.

Create a new cifs_wait_for_server_reconnect() helper that can be used
by both SMB2+ and CIFS reconnect code.

Signed-off-by: Paulo Alcantara (SUSE) <pc@manguebit.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
This commit is contained in:
Paulo Alcantara 2023-02-28 19:01:55 -03:00 committed by Steve French
parent b9ee2e307c
commit 1bcd548d93
4 changed files with 69 additions and 101 deletions
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1
fs/cifs/cifsproto.h
View File

@ -694,5 +694,6 @@ static inline int cifs_create_options(struct cifs_sb_info *cifs_sb, int options)
struct super_block *cifs_get_tcon_super(struct cifs_tcon *tcon);
void cifs_put_tcon_super(struct super_block *sb);
int cifs_wait_for_server_reconnect(struct TCP_Server_Info *server, bool retry);
#endif /* _CIFSPROTO_H */

43
fs/cifs/cifssmb.c
View File

@ -72,7 +72,6 @@ cifs_reconnect_tcon(struct cifs_tcon *tcon, int smb_command)
struct cifs_ses *ses;
struct TCP_Server_Info *server;
struct nls_table *nls_codepage;
int retries;
/*
* SMBs NegProt, SessSetup, uLogoff do not have tcon yet so check for
@ -102,45 +101,9 @@ cifs_reconnect_tcon(struct cifs_tcon *tcon, int smb_command)
}
spin_unlock(&tcon->tc_lock);
retries = server->nr_targets;
/*
* Give demultiplex thread up to 10 seconds to each target available for
* reconnect -- should be greater than cifs socket timeout which is 7
* seconds.
*/
while (server->tcpStatus == CifsNeedReconnect) {
rc = wait_event_interruptible_timeout(server->response_q,
(server->tcpStatus != CifsNeedReconnect),
10 * HZ);
if (rc < 0) {
cifs_dbg(FYI, "%s: aborting reconnect due to a received signal by the process\n",
__func__);
return -ERESTARTSYS;
}
/* are we still trying to reconnect? */
spin_lock(&server->srv_lock);
if (server->tcpStatus != CifsNeedReconnect) {
spin_unlock(&server->srv_lock);
break;
}
spin_unlock(&server->srv_lock);
if (retries && --retries)
continue;
/*
* on "soft" mounts we wait once. Hard mounts keep
* retrying until process is killed or server comes
* back on-line
*/
if (!tcon->retry) {
cifs_dbg(FYI, "gave up waiting on reconnect in smb_init\n");
return -EHOSTDOWN;
}
retries = server->nr_targets;
}
rc = cifs_wait_for_server_reconnect(server, tcon->retry);
if (rc)
return rc;
spin_lock(&ses->chan_lock);
if (!cifs_chan_needs_reconnect(ses, server) && !tcon->need_reconnect) {

44
fs/cifs/misc.c
View File

@ -1266,3 +1266,47 @@ int cifs_inval_name_dfs_link_error(const unsigned int xid,
return 0;
}
#endif
int cifs_wait_for_server_reconnect(struct TCP_Server_Info *server, bool retry)
{
int timeout = 10;
int rc;
spin_lock(&server->srv_lock);
if (server->tcpStatus != CifsNeedReconnect) {
spin_unlock(&server->srv_lock);
return 0;
}
timeout *= server->nr_targets;
spin_unlock(&server->srv_lock);
/*
* Give demultiplex thread up to 10 seconds to each target available for
* reconnect -- should be greater than cifs socket timeout which is 7
* seconds.
*
* On "soft" mounts we wait once. Hard mounts keep retrying until
* process is killed or server comes back on-line.
*/
do {
rc = wait_event_interruptible_timeout(server->response_q,
(server->tcpStatus != CifsNeedReconnect),
timeout * HZ);
if (rc < 0) {
cifs_dbg(FYI, "%s: aborting reconnect due to received signal\n",
__func__);
return -ERESTARTSYS;
}
/* are we still trying to reconnect? */
spin_lock(&server->srv_lock);
if (server->tcpStatus != CifsNeedReconnect) {
spin_unlock(&server->srv_lock);
return 0;
}
spin_unlock(&server->srv_lock);
} while (retry);
cifs_dbg(FYI, "%s: gave up waiting on reconnect\n", __func__);
return -EHOSTDOWN;
}

82
fs/cifs/smb2pdu.c
View File

@ -139,66 +139,6 @@ out:
return;
}
static int wait_for_server_reconnect(struct TCP_Server_Info *server,
__le16 smb2_command, bool retry)
{
int timeout = 10;
int rc;
spin_lock(&server->srv_lock);
if (server->tcpStatus != CifsNeedReconnect) {
spin_unlock(&server->srv_lock);
return 0;
}
timeout *= server->nr_targets;
spin_unlock(&server->srv_lock);
/*
* Return to caller for TREE_DISCONNECT and LOGOFF and CLOSE
* here since they are implicitly done when session drops.
*/
switch (smb2_command) {
/*
* BB Should we keep oplock break and add flush to exceptions?
*/
case SMB2_TREE_DISCONNECT:
case SMB2_CANCEL:
case SMB2_CLOSE:
case SMB2_OPLOCK_BREAK:
return -EAGAIN;
}
/*
* Give demultiplex thread up to 10 seconds to each target available for
* reconnect -- should be greater than cifs socket timeout which is 7
* seconds.
*
* On "soft" mounts we wait once. Hard mounts keep retrying until
* process is killed or server comes back on-line.
*/
do {
rc = wait_event_interruptible_timeout(server->response_q,
(server->tcpStatus != CifsNeedReconnect),
timeout * HZ);
if (rc < 0) {
cifs_dbg(FYI, "%s: aborting reconnect due to received signal\n",
__func__);
return -ERESTARTSYS;
}
/* are we still trying to reconnect? */
spin_lock(&server->srv_lock);
if (server->tcpStatus != CifsNeedReconnect) {
spin_unlock(&server->srv_lock);
return 0;
}
spin_unlock(&server->srv_lock);
} while (retry);
cifs_dbg(FYI, "%s: gave up waiting on reconnect\n", __func__);
return -EHOSTDOWN;
}
static int
smb2_reconnect(__le16 smb2_command, struct cifs_tcon *tcon,
struct TCP_Server_Info *server)
@ -243,7 +183,27 @@ smb2_reconnect(__le16 smb2_command, struct cifs_tcon *tcon,
(!tcon->ses->server) || !server)
return -EIO;
rc = wait_for_server_reconnect(server, smb2_command, tcon->retry);
spin_lock(&server->srv_lock);
if (server->tcpStatus == CifsNeedReconnect) {
/*
* Return to caller for TREE_DISCONNECT and LOGOFF and CLOSE
* here since they are implicitly done when session drops.
*/
switch (smb2_command) {
/*
* BB Should we keep oplock break and add flush to exceptions?
*/
case SMB2_TREE_DISCONNECT:
case SMB2_CANCEL:
case SMB2_CLOSE:
case SMB2_OPLOCK_BREAK:
spin_unlock(&server->srv_lock);
return -EAGAIN;
}
}
spin_unlock(&server->srv_lock);
rc = cifs_wait_for_server_reconnect(server, tcon->retry);
if (rc)
return rc;