diff options
author | Jeff Layton <jlayton@redhat.com> | 2008-11-14 13:53:46 -0500 |
---|---|---|
committer | Steve French <sfrench@us.ibm.com> | 2008-11-14 23:56:55 +0000 |
commit | 14fbf50d695207754daeb96270b3027a3821121f (patch) | |
tree | 05e80aa7e5e6a6bc07a9354f744ba9c599699569 /fs/cifs/connect.c | |
parent | e7ddee9037e7dd43de1ad08b51727e552aedd836 (diff) | |
download | kernel_samsung_smdk4412-14fbf50d695207754daeb96270b3027a3821121f.zip kernel_samsung_smdk4412-14fbf50d695207754daeb96270b3027a3821121f.tar.gz kernel_samsung_smdk4412-14fbf50d695207754daeb96270b3027a3821121f.tar.bz2 |
cifs: reinstate sharing of SMB sessions sans races
We do this by abandoning the global list of SMB sessions and instead
moving to a per-server list. This entails adding a new list head to the
TCP_Server_Info struct. The refcounting for the cifsSesInfo is moved to
a non-atomic variable. We have to protect it by a lock anyway, so there's
no benefit to making it an atomic. The list and refcount are protected
by the global cifs_tcp_ses_lock.
The patch also adds a new routines to find and put SMB sessions and
that properly take and put references under the lock.
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Steve French <sfrench@us.ibm.com>
Diffstat (limited to 'fs/cifs/connect.c')
-rw-r--r-- | fs/cifs/connect.c | 226 |
1 files changed, 125 insertions, 101 deletions
diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c index a031425..44130e0 100644 --- a/fs/cifs/connect.c +++ b/fs/cifs/connect.c @@ -144,23 +144,18 @@ cifs_reconnect(struct TCP_Server_Info *server) /* before reconnecting the tcp session, mark the smb session (uid) and the tid bad so they are not used until reconnected */ - read_lock(&GlobalSMBSeslock); - list_for_each(tmp, &GlobalSMBSessionList) { - ses = list_entry(tmp, struct cifsSesInfo, cifsSessionList); - if (ses->server) { - if (ses->server == server) { - ses->need_reconnect = true; - ses->ipc_tid = 0; - } - } - /* else tcp and smb sessions need reconnection */ + read_lock(&cifs_tcp_ses_lock); + list_for_each(tmp, &server->smb_ses_list) { + ses = list_entry(tmp, struct cifsSesInfo, smb_ses_list); + ses->need_reconnect = true; + ses->ipc_tid = 0; } + read_unlock(&cifs_tcp_ses_lock); list_for_each(tmp, &GlobalTreeConnectionList) { tcon = list_entry(tmp, struct cifsTconInfo, cifsConnectionList); if ((tcon->ses) && (tcon->ses->server == server)) tcon->need_reconnect = true; } - read_unlock(&GlobalSMBSeslock); /* do not want to be sending data on a socket we are freeing */ down(&server->tcpSem); if (server->ssocket) { @@ -696,29 +691,29 @@ multi_t2_fnd: if (smallbuf) /* no sense logging a debug message if NULL */ cifs_small_buf_release(smallbuf); - read_lock(&GlobalSMBSeslock); + /* + * BB: we shouldn't have to do any of this. It shouldn't be + * possible to exit from the thread with active SMB sessions + */ + read_lock(&cifs_tcp_ses_lock); if (list_empty(&server->pending_mid_q)) { /* loop through server session structures attached to this and mark them dead */ - list_for_each(tmp, &GlobalSMBSessionList) { - ses = - list_entry(tmp, struct cifsSesInfo, - cifsSessionList); - if (ses->server == server) { - ses->status = CifsExiting; - ses->server = NULL; - } + list_for_each(tmp, &server->smb_ses_list) { + ses = list_entry(tmp, struct cifsSesInfo, + smb_ses_list); + ses->status = CifsExiting; + ses->server = NULL; } - read_unlock(&GlobalSMBSeslock); + read_unlock(&cifs_tcp_ses_lock); } else { /* although we can not zero the server struct pointer yet, since there are active requests which may depnd on them, mark the corresponding SMB sessions as exiting too */ - list_for_each(tmp, &GlobalSMBSessionList) { + list_for_each(tmp, &server->smb_ses_list) { ses = list_entry(tmp, struct cifsSesInfo, - cifsSessionList); - if (ses->server == server) - ses->status = CifsExiting; + smb_ses_list); + ses->status = CifsExiting; } spin_lock(&GlobalMid_Lock); @@ -733,7 +728,7 @@ multi_t2_fnd: } } spin_unlock(&GlobalMid_Lock); - read_unlock(&GlobalSMBSeslock); + read_unlock(&cifs_tcp_ses_lock); /* 1/8th of sec is more than enough time for them to exit */ msleep(125); } @@ -755,14 +750,13 @@ multi_t2_fnd: if there are any pointing to this (e.g if a crazy root user tried to kill cifsd kernel thread explicitly this might happen) */ - write_lock(&GlobalSMBSeslock); - list_for_each(tmp, &GlobalSMBSessionList) { - ses = list_entry(tmp, struct cifsSesInfo, - cifsSessionList); - if (ses->server == server) - ses->server = NULL; + /* BB: This shouldn't be necessary, see above */ + read_lock(&cifs_tcp_ses_lock); + list_for_each(tmp, &server->smb_ses_list) { + ses = list_entry(tmp, struct cifsSesInfo, smb_ses_list); + ses->server = NULL; } - write_unlock(&GlobalSMBSeslock); + read_unlock(&cifs_tcp_ses_lock); kfree(server->hostname); task_to_wake = xchg(&server->tsk, NULL); @@ -1401,7 +1395,7 @@ cifs_find_tcp_session(struct sockaddr *addr) return NULL; } -void +static void cifs_put_tcp_session(struct TCP_Server_Info *server) { struct task_struct *task; @@ -1424,6 +1418,50 @@ cifs_put_tcp_session(struct TCP_Server_Info *server) force_sig(SIGKILL, task); } +static struct cifsSesInfo * +cifs_find_smb_ses(struct TCP_Server_Info *server, char *username) +{ + struct list_head *tmp; + struct cifsSesInfo *ses; + + write_lock(&cifs_tcp_ses_lock); + list_for_each(tmp, &server->smb_ses_list) { + ses = list_entry(tmp, struct cifsSesInfo, smb_ses_list); + if (strncmp(ses->userName, username, MAX_USERNAME_SIZE)) + continue; + + ++ses->ses_count; + write_unlock(&cifs_tcp_ses_lock); + return ses; + } + write_unlock(&cifs_tcp_ses_lock); + return NULL; +} + +static void +cifs_put_smb_ses(struct cifsSesInfo *ses) +{ + int xid; + struct TCP_Server_Info *server = ses->server; + + write_lock(&cifs_tcp_ses_lock); + if (--ses->ses_count > 0) { + write_unlock(&cifs_tcp_ses_lock); + return; + } + + list_del_init(&ses->smb_ses_list); + write_unlock(&cifs_tcp_ses_lock); + + if (ses->status == CifsGood) { + xid = GetXid(); + CIFSSMBLogoff(xid, ses); + _FreeXid(xid); + } + sesInfoFree(ses); + cifs_put_tcp_session(server); +} + int get_dfs_path(int xid, struct cifsSesInfo *pSesInfo, const char *old_path, const struct nls_table *nls_codepage, unsigned int *pnum_referrals, @@ -1958,7 +1996,6 @@ cifs_mount(struct super_block *sb, struct cifs_sb_info *cifs_sb, struct sockaddr_in6 *sin_server6 = (struct sockaddr_in6 *) &addr; struct smb_vol volume_info; struct cifsSesInfo *pSesInfo = NULL; - struct cifsSesInfo *existingCifsSes = NULL; struct cifsTconInfo *tcon = NULL; struct TCP_Server_Info *srvTcp = NULL; @@ -2112,6 +2149,7 @@ cifs_mount(struct super_block *sb, struct cifs_sb_info *cifs_sb, volume_info.target_rfc1001_name, 16); srvTcp->sequence_number = 0; INIT_LIST_HEAD(&srvTcp->tcp_ses_list); + INIT_LIST_HEAD(&srvTcp->smb_ses_list); ++srvTcp->srv_count; write_lock(&cifs_tcp_ses_lock); list_add(&srvTcp->tcp_ses_list, @@ -2120,10 +2158,16 @@ cifs_mount(struct super_block *sb, struct cifs_sb_info *cifs_sb, } } - if (existingCifsSes) { - pSesInfo = existingCifsSes; + pSesInfo = cifs_find_smb_ses(srvTcp, volume_info.username); + if (pSesInfo) { cFYI(1, ("Existing smb sess found (status=%d)", pSesInfo->status)); + /* + * The existing SMB session already has a reference to srvTcp, + * so we can put back the extra one we got before + */ + cifs_put_tcp_session(srvTcp); + down(&pSesInfo->sesSem); if (pSesInfo->need_reconnect) { cFYI(1, ("Session needs reconnect")); @@ -2134,41 +2178,44 @@ cifs_mount(struct super_block *sb, struct cifs_sb_info *cifs_sb, } else if (!rc) { cFYI(1, ("Existing smb sess not found")); pSesInfo = sesInfoAlloc(); - if (pSesInfo == NULL) + if (pSesInfo == NULL) { rc = -ENOMEM; - else { - pSesInfo->server = srvTcp; - sprintf(pSesInfo->serverName, "%u.%u.%u.%u", - NIPQUAD(sin_server->sin_addr.s_addr)); + goto mount_fail_check; } - if (!rc) { - /* volume_info.password freed at unmount */ - if (volume_info.password) { - pSesInfo->password = volume_info.password; - /* set to NULL to prevent freeing on exit */ - volume_info.password = NULL; - } - if (volume_info.username) - strncpy(pSesInfo->userName, - volume_info.username, - MAX_USERNAME_SIZE); - if (volume_info.domainname) { - int len = strlen(volume_info.domainname); - pSesInfo->domainName = - kmalloc(len + 1, GFP_KERNEL); - if (pSesInfo->domainName) - strcpy(pSesInfo->domainName, - volume_info.domainname); - } - pSesInfo->linux_uid = volume_info.linux_uid; - pSesInfo->overrideSecFlg = volume_info.secFlg; - down(&pSesInfo->sesSem); - /* BB FIXME need to pass vol->secFlgs BB */ - rc = cifs_setup_session(xid, pSesInfo, - cifs_sb->local_nls); - up(&pSesInfo->sesSem); - } + /* new SMB session uses our srvTcp ref */ + pSesInfo->server = srvTcp; + sprintf(pSesInfo->serverName, "%u.%u.%u.%u", + NIPQUAD(sin_server->sin_addr.s_addr)); + + write_lock(&cifs_tcp_ses_lock); + list_add(&pSesInfo->smb_ses_list, &srvTcp->smb_ses_list); + write_unlock(&cifs_tcp_ses_lock); + + /* volume_info.password freed at unmount */ + if (volume_info.password) { + pSesInfo->password = volume_info.password; + /* set to NULL to prevent freeing on exit */ + volume_info.password = NULL; + } + if (volume_info.username) + strncpy(pSesInfo->userName, volume_info.username, + MAX_USERNAME_SIZE); + if (volume_info.domainname) { + int len = strlen(volume_info.domainname); + pSesInfo->domainName = kmalloc(len + 1, GFP_KERNEL); + if (pSesInfo->domainName) + strcpy(pSesInfo->domainName, + volume_info.domainname); + } + pSesInfo->linux_uid = volume_info.linux_uid; + pSesInfo->overrideSecFlg = volume_info.secFlg; + down(&pSesInfo->sesSem); + + /* BB FIXME need to pass vol->secFlgs BB */ + rc = cifs_setup_session(xid, pSesInfo, + cifs_sb->local_nls); + up(&pSesInfo->sesSem); } /* search for existing tcon to this server share */ @@ -2209,11 +2256,9 @@ cifs_mount(struct super_block *sb, struct cifs_sb_info *cifs_sb, tcon->Flags)); } } - if (!rc) { - atomic_inc(&pSesInfo->inUse); - tcon->seal = volume_info.seal; - } else + if (rc) goto mount_fail_check; + tcon->seal = volume_info.seal; } /* we can have only one retry value for a connection @@ -2234,29 +2279,19 @@ cifs_mount(struct super_block *sb, struct cifs_sb_info *cifs_sb, /* BB FIXME fix time_gran to be larger for LANMAN sessions */ sb->s_time_gran = 100; -/* on error free sesinfo and tcon struct if needed */ mount_fail_check: + /* on error free sesinfo and tcon struct if needed */ if (rc) { /* 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)) - CIFSSMBLogoff(xid, pSesInfo); - else { - cFYI(1, ("No session or bad tcon")); - if (pSesInfo->server) - cifs_put_tcp_session( - pSesInfo->server); - } - sesInfoFree(pSesInfo); - /* pSesInfo = NULL; */ - } - } + /* should also end up putting our tcp session ref if needed */ + if (pSesInfo) + cifs_put_smb_ses(pSesInfo); + else + cifs_put_tcp_session(srvTcp); } else { atomic_inc(&tcon->useCount); cifs_sb->tcon = tcon; @@ -3551,16 +3586,7 @@ cifs_umount(struct super_block *sb, struct cifs_sb_info *cifs_sb) } DeleteTconOplockQEntries(cifs_sb->tcon); tconInfoFree(cifs_sb->tcon); - if ((ses) && (ses->server)) { - /* save off task so we do not refer to ses later */ - cFYI(1, ("About to do SMBLogoff ")); - rc = CIFSSMBLogoff(xid, ses); - if (rc == -EBUSY) { - FreeXid(xid); - return 0; - } - } else - cFYI(1, ("No session or bad tcon")); + cifs_put_smb_ses(ses); } cifs_sb->tcon = NULL; @@ -3568,8 +3594,6 @@ cifs_umount(struct super_block *sb, struct cifs_sb_info *cifs_sb) cifs_sb->prepathlen = 0; cifs_sb->prepath = NULL; kfree(tmp); - if (ses) - sesInfoFree(ses); FreeXid(xid); return rc; |