cifs: prevent infinite recursion in cifs_reconnect_tcon
cifs_reconnect_tcon is called from smb_init. After a successful
reconnect, cifs_reconnect_tcon will call reset_cifs_unix_caps. That
function will, in turn call CIFSSMBQFSUnixInfo and CIFSSMBSetFSUnixInfo.
Those functions also call smb_init.
It's possible for the session and tcon reconnect to succeed, and then
for another cifs_reconnect to occur before CIFSSMBQFSUnixInfo or
CIFSSMBSetFSUnixInfo to be called. That'll cause those functions to call
smb_init and cifs_reconnect_tcon again, ad infinitum...
Break the infinite recursion by having those functions use a new
smb_init variant that doesn't attempt to perform a reconnect.
Reported-and-Tested-by: Michal Suchanek <hramrach@centrum.cz>
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Steve French <sfrench@us.ibm.com>
diff --git a/fs/cifs/cifssmb.c b/fs/cifs/cifssmb.c
index c65c341..7e83b35 100644
--- a/fs/cifs/cifssmb.c
+++ b/fs/cifs/cifssmb.c
@@ -232,7 +232,7 @@
small_smb_init(int smb_command, int wct, struct cifsTconInfo *tcon,
void **request_buf)
{
- int rc = 0;
+ int rc;
rc = cifs_reconnect_tcon(tcon, smb_command);
if (rc)
@@ -250,7 +250,7 @@
if (tcon != NULL)
cifs_stats_inc(&tcon->num_smbs_sent);
- return rc;
+ return 0;
}
int
@@ -281,16 +281,9 @@
/* If the return code is zero, this function must fill in request_buf pointer */
static int
-smb_init(int smb_command, int wct, struct cifsTconInfo *tcon,
- void **request_buf /* returned */ ,
- void **response_buf /* returned */ )
+__smb_init(int smb_command, int wct, struct cifsTconInfo *tcon,
+ void **request_buf, void **response_buf)
{
- int rc = 0;
-
- rc = cifs_reconnect_tcon(tcon, smb_command);
- if (rc)
- return rc;
-
*request_buf = cifs_buf_get();
if (*request_buf == NULL) {
/* BB should we add a retry in here if not a writepage? */
@@ -309,7 +302,31 @@
if (tcon != NULL)
cifs_stats_inc(&tcon->num_smbs_sent);
- return rc;
+ return 0;
+}
+
+/* If the return code is zero, this function must fill in request_buf pointer */
+static int
+smb_init(int smb_command, int wct, struct cifsTconInfo *tcon,
+ void **request_buf, void **response_buf)
+{
+ int rc;
+
+ rc = cifs_reconnect_tcon(tcon, smb_command);
+ if (rc)
+ return rc;
+
+ return __smb_init(smb_command, wct, tcon, request_buf, response_buf);
+}
+
+static int
+smb_init_no_reconnect(int smb_command, int wct, struct cifsTconInfo *tcon,
+ void **request_buf, void **response_buf)
+{
+ if (tcon->ses->need_reconnect || tcon->need_reconnect)
+ return -EHOSTDOWN;
+
+ return __smb_init(smb_command, wct, tcon, request_buf, response_buf);
}
static int validate_t2(struct smb_t2_rsp *pSMB)
@@ -4534,8 +4551,8 @@
cFYI(1, "In QFSUnixInfo");
QFSUnixRetry:
- rc = smb_init(SMB_COM_TRANSACTION2, 15, tcon, (void **) &pSMB,
- (void **) &pSMBr);
+ rc = smb_init_no_reconnect(SMB_COM_TRANSACTION2, 15, tcon,
+ (void **) &pSMB, (void **) &pSMBr);
if (rc)
return rc;
@@ -4604,8 +4621,8 @@
cFYI(1, "In SETFSUnixInfo");
SETFSUnixRetry:
/* BB switch to small buf init to save memory */
- rc = smb_init(SMB_COM_TRANSACTION2, 15, tcon, (void **) &pSMB,
- (void **) &pSMBr);
+ rc = smb_init_no_reconnect(SMB_COM_TRANSACTION2, 15, tcon,
+ (void **) &pSMB, (void **) &pSMBr);
if (rc)
return rc;