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cifs: disable sharing session and tcon and add new TCP sharing code

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The code that allows these structs to be shared is extremely racy.
Disable the sharing of SMB and tcon structs for now until we can
come up with a way to do this that's race free.

We want to continue to share TCP sessions, however since they are
required for multiuser mounts. For that, implement a new (hopefully
race-free) scheme. Add a new global list of TCP sessions, and take
care to get a reference to it whenever we're dealing with one.

Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Steve French <sfrench@us.ibm.com>
This commit is contained in:
Jeff Layton 2008-11-14 13:44:38 -05:00 committed by Steve French
parent 3ec332ef7a
commit e7ddee9037
6 changed files with 95 additions and 149 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
fs/cifs/cifs_debug.c
View File

@ -144,7 +144,7 @@ static int cifs_debug_data_proc_show(struct seq_file *m, void *v)
seq_printf(m, "TCP status: %d\n\tLocal Users To "
"Server: %d SecMode: 0x%x Req On Wire: %d",
ses->server->tcpStatus,
atomic_read(&ses->server->socketUseCount),
ses->server->srv_count,
ses->server->secMode,
atomic_read(&ses->server->inFlight));

3
fs/cifs/cifsfs.c
View File

@ -1059,7 +1059,7 @@ init_cifs(void)
{
int rc = 0;
cifs_proc_init();
INIT_LIST_HEAD(&global_cifs_sock_list);
INIT_LIST_HEAD(&cifs_tcp_ses_list);
INIT_LIST_HEAD(&GlobalSMBSessionList); /* BB to be removed by jl */
INIT_LIST_HEAD(&GlobalTreeConnectionList); /* BB to be removed by jl */
INIT_LIST_HEAD(&GlobalOplock_Q);
@ -1089,6 +1089,7 @@ init_cifs(void)
GlobalMaxActiveXid = 0;
memset(Local_System_Name, 0, 15);
rwlock_init(&GlobalSMBSeslock);
rwlock_init(&cifs_tcp_ses_lock);
spin_lock_init(&GlobalMid_Lock);
if (cifs_max_pending < 2) {

17
fs/cifs/cifsglob.h
View File

@ -123,6 +123,7 @@ struct cifs_cred {
struct TCP_Server_Info {
struct list_head tcp_ses_list;
struct list_head smb_ses_list;
int srv_count; /* reference counter */
/* 15 character server name + 0x20 16th byte indicating type = srv */
char server_RFC1001_name[SERVER_NAME_LEN_WITH_NULL];
char unicode_server_Name[SERVER_NAME_LEN_WITH_NULL * 2];
@ -144,7 +145,6 @@ struct TCP_Server_Info {
bool svlocal:1; /* local server or remote */
bool noblocksnd; /* use blocking sendmsg */
bool noautotune; /* do not autotune send buf sizes */
atomic_t socketUseCount; /* number of open cifs sessions on socket */
atomic_t inFlight; /* number of requests on the wire to server */
#ifdef CONFIG_CIFS_STATS2
atomic_t inSend; /* requests trying to send */
@ -591,13 +591,18 @@ require use of the stronger protocol */
#define GLOBAL_EXTERN extern
#endif
/* the list of TCP_Server_Info structures, ie each of the sockets
/*
* the list of TCP_Server_Info structures, ie each of the sockets
* connecting our client to a distinct server (ip address), is
* chained together by global_cifs_sock_list. The list of all our SMB
* chained together by cifs_tcp_ses_list. The list of all our SMB
* sessions (and from that the tree connections) can be found
* by iterating over global_cifs_sock_list */
GLOBAL_EXTERN struct list_head global_cifs_sock_list;
* by iterating over cifs_tcp_ses_list
*/
GLOBAL_EXTERN struct list_head cifs_tcp_ses_list;
/* protects cifs_tcp_ses_list and srv_count for each tcp session */
GLOBAL_EXTERN rwlock_t cifs_tcp_ses_lock;
GLOBAL_EXTERN struct list_head GlobalSMBSessionList; /* BB to be removed by jl*/
GLOBAL_EXTERN struct list_head GlobalTreeConnectionList; /* BB to be removed */
GLOBAL_EXTERN rwlock_t GlobalSMBSeslock; /* protects list inserts on 3 above */

1
fs/cifs/cifsproto.h
View File

@ -102,6 +102,7 @@ extern void acl_to_uid_mode(struct inode *inode, const char *path,
const __u16 *pfid);
extern int mode_to_acl(struct inode *inode, const char *path, __u64);
extern void cifs_put_tcp_session(struct TCP_Server_Info *server);
extern int cifs_mount(struct super_block *, struct cifs_sb_info *, char *,
const char *);
extern int cifs_umount(struct super_block *, struct cifs_sb_info *);

18
fs/cifs/cifssmb.c
View File

@ -664,8 +664,9 @@ CIFSSMBNegotiate(unsigned int xid, struct cifsSesInfo *ses)
rc = -EIO;
goto neg_err_exit;
}
if (server->socketUseCount.counter > 1) {
read_lock(&cifs_tcp_ses_lock);
if (server->srv_count > 1) {
read_unlock(&cifs_tcp_ses_lock);
if (memcmp(server->server_GUID,
pSMBr->u.extended_response.
GUID, 16) != 0) {
@ -674,9 +675,11 @@ CIFSSMBNegotiate(unsigned int xid, struct cifsSesInfo *ses)
pSMBr->u.extended_response.GUID,
16);
}
} else
} else {
read_unlock(&cifs_tcp_ses_lock);
memcpy(server->server_GUID,
pSMBr->u.extended_response.GUID, 16);
}
if (count == 16) {
server->secType = RawNTLMSSP;
@ -830,12 +833,9 @@ CIFSSMBLogoff(const int xid, struct cifsSesInfo *ses)
pSMB->AndXCommand = 0xFF;
rc = SendReceiveNoRsp(xid, ses, (struct smb_hdr *) pSMB, 0);
session_already_dead:
atomic_dec(&ses->server->socketUseCount);
if (atomic_read(&ses->server->socketUseCount) == 0) {
spin_lock(&GlobalMid_Lock);
ses->server->tcpStatus = CifsExiting;
spin_unlock(&GlobalMid_Lock);
rc = -ESHUTDOWN;
if (ses->server) {
cifs_put_tcp_session(ses->server);
rc = 0;
}
up(&ses->sesSem);

203
fs/cifs/connect.c
View File

@ -659,6 +659,11 @@ multi_t2_fnd:
}
} /* end while !EXITING */
/* take it off the list, if it's not already */
write_lock(&cifs_tcp_ses_lock);
list_del_init(&server->tcp_ses_list);
write_unlock(&cifs_tcp_ses_lock);
spin_lock(&GlobalMid_Lock);
server->tcpStatus = CifsExiting;
spin_unlock(&GlobalMid_Lock);
@ -1357,92 +1362,66 @@ cifs_parse_mount_options(char *options, const char *devname,
return 0;
}
static struct cifsSesInfo *
cifs_find_tcp_session(struct in_addr *target_ip_addr,
struct in6_addr *target_ip6_addr,
char *userName, struct TCP_Server_Info **psrvTcp)
static struct TCP_Server_Info *
cifs_find_tcp_session(struct sockaddr *addr)
{
struct list_head *tmp;
struct cifsSesInfo *ses;
struct TCP_Server_Info *server;
struct sockaddr_in *addr4 = (struct sockaddr_in *) addr;
struct sockaddr_in6 *addr6 = (struct sockaddr_in6 *) addr;
*psrvTcp = NULL;
write_lock(&cifs_tcp_ses_lock);
list_for_each(tmp, &cifs_tcp_ses_list) {
server = list_entry(tmp, struct TCP_Server_Info,
tcp_ses_list);
read_lock(&GlobalSMBSeslock);
list_for_each(tmp, &GlobalSMBSessionList) {
ses = list_entry(tmp, struct cifsSesInfo, cifsSessionList);
if (!ses->server)
/*
* the demux thread can exit on its own while still in CifsNew
* so don't accept any sockets in that state. Since the
* tcpStatus never changes back to CifsNew it's safe to check
* for this without a lock.
*/
if (server->tcpStatus == CifsNew)
continue;
if (target_ip_addr &&
ses->server->addr.sockAddr.sin_addr.s_addr != target_ip_addr->s_addr)
continue;
else if (target_ip6_addr &&
memcmp(&ses->server->addr.sockAddr6.sin6_addr,
target_ip6_addr, sizeof(*target_ip6_addr)))
continue;
/* BB lock server and tcp session; increment use count here?? */
if (addr->sa_family == AF_INET &&
(addr4->sin_addr.s_addr !=
server->addr.sockAddr.sin_addr.s_addr))
continue;
else if (addr->sa_family == AF_INET6 &&
memcmp(&server->addr.sockAddr6.sin6_addr,
&addr6->sin6_addr, sizeof(addr6->sin6_addr)))
continue;
/* found a match on the TCP session */
*psrvTcp = ses->server;
/* BB check if reconnection needed */
if (strncmp(ses->userName, userName, MAX_USERNAME_SIZE) == 0) {
read_unlock(&GlobalSMBSeslock);
/* Found exact match on both TCP and
SMB sessions */
return ses;
}
/* else tcp and smb sessions need reconnection */
++server->srv_count;
write_unlock(&cifs_tcp_ses_lock);
return server;
}
read_unlock(&GlobalSMBSeslock);
write_unlock(&cifs_tcp_ses_lock);
return NULL;
}
static struct cifsTconInfo *
find_unc(__be32 new_target_ip_addr, char *uncName, char *userName)
void
cifs_put_tcp_session(struct TCP_Server_Info *server)
{
struct list_head *tmp;
struct cifsTconInfo *tcon;
__be32 old_ip;
struct task_struct *task;
read_lock(&GlobalSMBSeslock);
list_for_each(tmp, &GlobalTreeConnectionList) {
cFYI(1, ("Next tcon"));
tcon = list_entry(tmp, struct cifsTconInfo, cifsConnectionList);
if (!tcon->ses || !tcon->ses->server)
continue;
old_ip = tcon->ses->server->addr.sockAddr.sin_addr.s_addr;
cFYI(1, ("old ip addr: %x == new ip %x ?",
old_ip, new_target_ip_addr));
if (old_ip != new_target_ip_addr)
continue;
/* BB lock tcon, server, tcp session and increment use count? */
/* found a match on the TCP session */
/* BB check if reconnection needed */
cFYI(1, ("IP match, old UNC: %s new: %s",
tcon->treeName, uncName));
if (strncmp(tcon->treeName, uncName, MAX_TREE_SIZE))
continue;
cFYI(1, ("and old usr: %s new: %s",
tcon->treeName, uncName));
if (strncmp(tcon->ses->userName, userName, MAX_USERNAME_SIZE))
continue;
/* matched smb session (user name) */
read_unlock(&GlobalSMBSeslock);
return tcon;
write_lock(&cifs_tcp_ses_lock);
if (--server->srv_count > 0) {
write_unlock(&cifs_tcp_ses_lock);
return;
}
read_unlock(&GlobalSMBSeslock);
return NULL;
list_del_init(&server->tcp_ses_list);
write_unlock(&cifs_tcp_ses_lock);
spin_lock(&GlobalMid_Lock);
server->tcpStatus = CifsExiting;
spin_unlock(&GlobalMid_Lock);
task = xchg(&server->tsk, NULL);
if (task)
force_sig(SIGKILL, task);
}
int
@ -1881,16 +1860,6 @@ convert_delimiter(char *path, char delim)
}
}
static void
kill_cifsd(struct TCP_Server_Info *server)
{
struct task_struct *task;
task = xchg(&server->tsk, NULL);
if (task)
force_sig(SIGKILL, task);
}
static void setup_cifs_sb(struct smb_vol *pvolume_info,
struct cifs_sb_info *cifs_sb)
{
@ -2069,21 +2038,10 @@ cifs_mount(struct super_block *sb, struct cifs_sb_info *cifs_sb,
}
}
if (addr.sa_family == AF_INET)
existingCifsSes = cifs_find_tcp_session(&sin_server->sin_addr,
NULL /* no ipv6 addr */,
volume_info.username, &srvTcp);
else if (addr.sa_family == AF_INET6) {
cFYI(1, ("looking for ipv6 address"));
existingCifsSes = cifs_find_tcp_session(NULL /* no ipv4 addr */,
&sin_server6->sin6_addr,
volume_info.username, &srvTcp);
} else {
rc = -EINVAL;
goto out;
}
if (!srvTcp) {
srvTcp = cifs_find_tcp_session(&addr);
if (srvTcp) {
cFYI(1, ("Existing tcp session with server found"));
} else { /* create socket */
if (addr.sa_family == AF_INET6) {
cFYI(1, ("attempting ipv6 connect"));
/* BB should we allow ipv6 on port 139? */
@ -2153,6 +2111,12 @@ cifs_mount(struct super_block *sb, struct cifs_sb_info *cifs_sb,
memcpy(srvTcp->server_RFC1001_name,
volume_info.target_rfc1001_name, 16);
srvTcp->sequence_number = 0;
INIT_LIST_HEAD(&srvTcp->tcp_ses_list);
++srvTcp->srv_count;
write_lock(&cifs_tcp_ses_lock);
list_add(&srvTcp->tcp_ses_list,
&cifs_tcp_ses_list);
write_unlock(&cifs_tcp_ses_lock);
}
}
@ -2204,8 +2168,6 @@ cifs_mount(struct super_block *sb, struct cifs_sb_info *cifs_sb,
rc = cifs_setup_session(xid, pSesInfo,
cifs_sb->local_nls);
up(&pSesInfo->sesSem);
if (!rc)
atomic_inc(&srvTcp->socketUseCount);
}
}
@ -2213,9 +2175,6 @@ cifs_mount(struct super_block *sb, struct cifs_sb_info *cifs_sb,
if (!rc) {
setup_cifs_sb(&volume_info, cifs_sb);
tcon =
find_unc(sin_server->sin_addr.s_addr, volume_info.UNC,
volume_info.username);
if (tcon) {
cFYI(1, ("Found match on UNC path"));
if (tcon->seal != volume_info.seal)
@ -2278,35 +2237,21 @@ cifs_mount(struct super_block *sb, struct cifs_sb_info *cifs_sb,
/* on error free sesinfo and tcon struct if needed */
mount_fail_check:
if (rc) {
/* if session setup failed, use count is zero but
we still need to free cifsd thread */
if (atomic_read(&srvTcp->socketUseCount) == 0) {
spin_lock(&GlobalMid_Lock);
srvTcp->tcpStatus = CifsExiting;
spin_unlock(&GlobalMid_Lock);
kill_cifsd(srvTcp);
}
/* If find_unc succeeded then rc == 0 so we can not end */
if (tcon) /* up accidently freeing someone elses tcon struct */
/* If find_unc succeeded then rc == 0 so we can not end */
/* up accidently freeing someone elses tcon struct */
if (tcon)
tconInfoFree(tcon);
if (existingCifsSes == NULL) {
if (pSesInfo) {
if ((pSesInfo->server) &&
(pSesInfo->status == CifsGood)) {
int temp_rc;
temp_rc = CIFSSMBLogoff(xid, pSesInfo);
/* if the socketUseCount is now zero */
if ((temp_rc == -ESHUTDOWN) &&
(pSesInfo->server))
kill_cifsd(pSesInfo->server);
} else {
(pSesInfo->status == CifsGood))
CIFSSMBLogoff(xid, pSesInfo);
else {
cFYI(1, ("No session or bad tcon"));
if (pSesInfo->server) {
spin_lock(&GlobalMid_Lock);
srvTcp->tcpStatus = CifsExiting;
spin_unlock(&GlobalMid_Lock);
kill_cifsd(pSesInfo->server);
}
if (pSesInfo->server)
cifs_put_tcp_session(
pSesInfo->server);
}
sesInfoFree(pSesInfo);
/* pSesInfo = NULL; */
@ -3613,13 +3558,7 @@ cifs_umount(struct super_block *sb, struct cifs_sb_info *cifs_sb)
if (rc == -EBUSY) {
FreeXid(xid);
return 0;
} else if (rc == -ESHUTDOWN) {
cFYI(1, ("Waking up socket by sending signal"));
if (ses->server)
kill_cifsd(ses->server);
rc = 0;
} /* else - we have an smb session
left on this socket do not kill cifsd */
}
} else
cFYI(1, ("No session or bad tcon"));
}