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Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * fs/cifs/cifsglob.h
3 *
Steve French67010fb2005-04-28 22:41:09 -07004 * Copyright (C) International Business Machines Corp., 2002,2005
Linus Torvalds1da177e2005-04-16 15:20:36 -07005 * Author(s): Steve French (sfrench@us.ibm.com)
6 *
7 * This library is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU Lesser General Public License as published
9 * by the Free Software Foundation; either version 2.1 of the License, or
10 * (at your option) any later version.
11 *
12 * This library is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See
15 * the GNU Lesser General Public License for more details.
16 *
17 */
18#include <linux/in.h>
19#include <linux/in6.h>
20#include "cifs_fs_sb.h"
21/*
22 * The sizes of various internal tables and strings
23 */
24#define MAX_UID_INFO 16
25#define MAX_SES_INFO 2
26#define MAX_TCON_INFO 4
27
28#define MAX_TREE_SIZE 2 + MAX_SERVER_SIZE + 1 + MAX_SHARE_SIZE + 1
29#define MAX_SERVER_SIZE 15
30#define MAX_SHARE_SIZE 64 /* used to be 20 - this should still be enough */
31#define MAX_USERNAME_SIZE 32 /* 32 is to allow for 15 char names + null
32 termination then *2 for unicode versions */
33#define MAX_PASSWORD_SIZE 16
34
35#define CIFS_MIN_RCV_POOL 4
36
37/*
38 * MAX_REQ is the maximum number of requests that WE will send
39 * on one socket concurently. It also matches the most common
40 * value of max multiplex returned by servers. We may
41 * eventually want to use the negotiated value (in case
42 * future servers can handle more) when we are more confident that
43 * we will not have problems oveloading the socket with pending
44 * write data.
45 */
46#define CIFS_MAX_REQ 50
47
48#define SERVER_NAME_LENGTH 15
49#define SERVER_NAME_LEN_WITH_NULL (SERVER_NAME_LENGTH + 1)
50
51/* used to define string lengths for reversing unicode strings */
52/* (256+1)*2 = 514 */
53/* (max path length + 1 for null) * 2 for unicode */
54#define MAX_NAME 514
55
56#include "cifspdu.h"
57
58#ifndef FALSE
59#define FALSE 0
60#endif
61
62#ifndef TRUE
63#define TRUE 1
64#endif
65
66#ifndef XATTR_DOS_ATTRIB
67#define XATTR_DOS_ATTRIB "user.DOSATTRIB"
68#endif
69
70/*
71 * This information is kept on every Server we know about.
72 *
73 * Some things to note:
74 *
75 */
76#define SERVER_NAME_LEN_WITH_NULL (SERVER_NAME_LENGTH + 1)
77
78/*
79 * CIFS vfs client Status information (based on what we know.)
80 */
81
82 /* associated with each tcp and smb session */
83enum statusEnum {
84 CifsNew = 0,
85 CifsGood,
86 CifsExiting,
87 CifsNeedReconnect
88};
89
90enum securityEnum {
91 NTLM = 0, /* Legacy NTLM012 auth with NTLM hash */
92 NTLMv2, /* Legacy NTLM auth with NTLMv2 hash */
93 RawNTLMSSP, /* NTLMSSP without SPNEGO */
94 NTLMSSP, /* NTLMSSP via SPNEGO */
95 Kerberos /* Kerberos via SPNEGO */
96};
97
98enum protocolEnum {
99 IPV4 = 0,
100 IPV6,
101 SCTP
102 /* Netbios frames protocol not supported at this time */
103};
104
105/*
106 *****************************************************************
107 * Except the CIFS PDUs themselves all the
108 * globally interesting structs should go here
109 *****************************************************************
110 */
111
112struct TCP_Server_Info {
Steve Frencha10faeb22005-08-22 21:38:31 -0700113 /* 15 character server name + 0x20 16th byte indicating type = srv */
114 char server_RFC1001_name[SERVER_NAME_LEN_WITH_NULL];
Steve Frenchd3485d32005-08-19 11:04:29 -0700115 char unicode_server_Name[SERVER_NAME_LEN_WITH_NULL * 2];
Linus Torvalds1da177e2005-04-16 15:20:36 -0700116 struct socket *ssocket;
117 union {
118 struct sockaddr_in sockAddr;
119 struct sockaddr_in6 sockAddr6;
120 } addr;
121 wait_queue_head_t response_q;
122 wait_queue_head_t request_q; /* if more than maxmpx to srvr must block*/
123 struct list_head pending_mid_q;
124 void *Server_NlsInfo; /* BB - placeholder for future NLS info */
125 unsigned short server_codepage; /* codepage for the server */
Steve French131afd02005-10-07 09:51:05 -0700126 unsigned long ip_address; /* IP addr for the server if known */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700127 enum protocolEnum protocolType;
128 char versionMajor;
129 char versionMinor;
130 unsigned svlocal:1; /* local server or remote */
131 atomic_t socketUseCount; /* number of open cifs sessions on socket */
132 atomic_t inFlight; /* number of requests on the wire to server */
Steve French131afd02005-10-07 09:51:05 -0700133#ifdef CONFIG_CIFS_STATS2
134 atomic_t inSend; /* requests trying to send */
135 atomic_t num_waiters; /* blocked waiting to get in sendrecv */
136#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -0700137 enum statusEnum tcpStatus; /* what we think the status is */
138 struct semaphore tcpSem;
139 struct task_struct *tsk;
140 char server_GUID[16];
141 char secMode;
142 enum securityEnum secType;
143 unsigned int maxReq; /* Clients should submit no more */
144 /* than maxReq distinct unanswered SMBs to the server when using */
145 /* multiplexed reads or writes */
146 unsigned int maxBuf; /* maxBuf specifies the maximum */
147 /* message size the server can send or receive for non-raw SMBs */
148 unsigned int maxRw; /* maxRw specifies the maximum */
149 /* message size the server can send or receive for */
150 /* SMB_COM_WRITE_RAW or SMB_COM_READ_RAW. */
151 char sessid[4]; /* unique token id for this session */
152 /* (returned on Negotiate */
153 int capabilities; /* allow selective disabling of caps by smb sess */
154 __u16 timeZone;
Steve French1982c342005-08-17 12:38:22 -0700155 __u16 CurrentMid; /* multiplex id - rotating counter */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700156 char cryptKey[CIFS_CRYPTO_KEY_SIZE];
Steve Frencha10faeb22005-08-22 21:38:31 -0700157 /* 16th byte of RFC1001 workstation name is always null */
158 char workstation_RFC1001_name[SERVER_NAME_LEN_WITH_NULL];
Steve Frenchad009ac2005-04-28 22:41:05 -0700159 __u32 sequence_number; /* needed for CIFS PDU signature */
160 char mac_signing_key[CIFS_SESSION_KEY_SIZE + 16];
Linus Torvalds1da177e2005-04-16 15:20:36 -0700161};
162
163/*
164 * The following is our shortcut to user information. We surface the uid,
165 * and name. We always get the password on the fly in case it
166 * has changed. We also hang a list of sessions owned by this user off here.
167 */
168struct cifsUidInfo {
169 struct list_head userList;
170 struct list_head sessionList; /* SMB sessions for this user */
171 uid_t linux_uid;
172 char user[MAX_USERNAME_SIZE + 1]; /* ascii name of user */
173 /* BB may need ptr or callback for PAM or WinBind info */
174};
175
176/*
177 * Session structure. One of these for each uid session with a particular host
178 */
179struct cifsSesInfo {
180 struct list_head cifsSessionList;
181 struct semaphore sesSem;
182 struct cifsUidInfo *uidInfo; /* pointer to user info */
183 struct TCP_Server_Info *server; /* pointer to server info */
184 atomic_t inUse; /* # of mounts (tree connections) on this ses */
185 enum statusEnum status;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700186 __u16 ipc_tid; /* special tid for connection to IPC share */
187 __u16 flags;
Steve Frenchad009ac2005-04-28 22:41:05 -0700188 char *serverOS; /* name of operating system underlying server */
189 char *serverNOS; /* name of network operating system of server */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700190 char *serverDomain; /* security realm of server */
191 int Suid; /* remote smb uid */
192 uid_t linux_uid; /* local Linux uid */
193 int capabilities;
Steve Frenchad009ac2005-04-28 22:41:05 -0700194 char serverName[SERVER_NAME_LEN_WITH_NULL * 2]; /* BB make bigger for
195 TCP names - will ipv6 and sctp addresses fit? */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700196 char userName[MAX_USERNAME_SIZE + 1];
197 char domainName[MAX_USERNAME_SIZE + 1];
198 char * password;
199};
200/* session flags */
201#define CIFS_SES_NT4 1
202
203/*
204 * there is one of these for each connection to a resource on a particular
205 * session
206 */
207struct cifsTconInfo {
208 struct list_head cifsConnectionList;
209 struct list_head openFileList;
210 struct semaphore tconSem;
211 struct cifsSesInfo *ses; /* pointer to session associated with */
212 char treeName[MAX_TREE_SIZE + 1]; /* UNC name of resource (in ASCII not UTF) */
213 char *nativeFileSystem;
214 __u16 tid; /* The 2 byte tree id */
215 __u16 Flags; /* optional support bits */
216 enum statusEnum tidStatus;
217 atomic_t useCount; /* how many mounts (explicit or implicit) to this share */
218#ifdef CONFIG_CIFS_STATS
219 atomic_t num_smbs_sent;
220 atomic_t num_writes;
221 atomic_t num_reads;
222 atomic_t num_oplock_brks;
223 atomic_t num_opens;
Steve Frencha5a2b482005-08-20 21:42:53 -0700224 atomic_t num_closes;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700225 atomic_t num_deletes;
226 atomic_t num_mkdirs;
227 atomic_t num_rmdirs;
228 atomic_t num_renames;
229 atomic_t num_t2renames;
Steve Frenchdfb75332005-06-22 17:13:47 -0700230 atomic_t num_ffirst;
231 atomic_t num_fnext;
232 atomic_t num_fclose;
Steve Frencha5a2b482005-08-20 21:42:53 -0700233 atomic_t num_hardlinks;
234 atomic_t num_symlinks;
235 atomic_t num_locks;
Steve French0a4b92c2006-01-12 15:44:21 -0800236 atomic_t num_acl_get;
237 atomic_t num_acl_set;
Steve Frencha5a2b482005-08-20 21:42:53 -0700238#ifdef CONFIG_CIFS_STATS2
239 unsigned long long time_writes;
240 unsigned long long time_reads;
241 unsigned long long time_opens;
242 unsigned long long time_deletes;
243 unsigned long long time_closes;
244 unsigned long long time_mkdirs;
245 unsigned long long time_rmdirs;
246 unsigned long long time_renames;
247 unsigned long long time_t2renames;
248 unsigned long long time_ffirst;
249 unsigned long long time_fnext;
250 unsigned long long time_fclose;
251#endif /* CONFIG_CIFS_STATS2 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700252 __u64 bytes_read;
253 __u64 bytes_written;
254 spinlock_t stat_lock;
Steve Frencha5a2b482005-08-20 21:42:53 -0700255#endif /* CONFIG_CIFS_STATS */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700256 FILE_SYSTEM_DEVICE_INFO fsDevInfo;
257 FILE_SYSTEM_ATTRIBUTE_INFO fsAttrInfo; /* ok if file system name truncated */
258 FILE_SYSTEM_UNIX_INFO fsUnixInfo;
259 unsigned retry:1;
Steve Frenchd3485d32005-08-19 11:04:29 -0700260 unsigned nocase:1;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700261 /* BB add field for back pointer to sb struct? */
262};
263
264/*
265 * This info hangs off the cifsFileInfo structure. This is used to track
266 * byte stream locks on the file
267 */
268struct cifsLockInfo {
269 struct cifsLockInfo *next;
270 int start;
271 int length;
272 int type;
273};
274
275/*
276 * One of these for each open instance of a file
277 */
278struct cifs_search_info {
279 loff_t index_of_last_entry;
280 __u16 entries_in_buffer;
281 __u16 info_level;
282 __u32 resume_key;
283 char * ntwrk_buf_start;
284 char * srch_entries_start;
285 char * presume_name;
286 unsigned int resume_name_len;
287 unsigned endOfSearch:1;
288 unsigned emptyDir:1;
289 unsigned unicode:1;
Steve Frenchec637e32005-12-12 20:53:18 -0800290 unsigned smallBuf:1; /* so we know which buf_release function to call */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700291};
292
293struct cifsFileInfo {
294 struct list_head tlist; /* pointer to next fid owned by tcon */
295 struct list_head flist; /* next fid (file instance) for this inode */
296 unsigned int uid; /* allows finding which FileInfo structure */
297 __u32 pid; /* process id who opened file */
298 __u16 netfid; /* file id from remote */
299 /* BB add lock scope info here if needed */ ;
300 /* lock scope id (0 if none) */
301 struct file * pfile; /* needed for writepage */
302 struct inode * pInode; /* needed for oplock break */
303 unsigned closePend:1; /* file is marked to close */
304 unsigned invalidHandle:1; /* file closed via session abend */
Steve French23e7dd72005-10-20 13:44:56 -0700305 atomic_t wrtPending; /* handle in use - defer close */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700306 struct semaphore fh_sem; /* prevents reopen race after dead ses*/
307 char * search_resume_name; /* BB removeme BB */
308 unsigned int resume_name_length; /* BB removeme - field renamed and moved BB */
309 struct cifs_search_info srch_inf;
310};
311
312/*
313 * One of these for each file inode
314 */
315
316struct cifsInodeInfo {
317 struct list_head lockList;
318 /* BB add in lists for dirty pages - i.e. write caching info for oplock */
319 struct list_head openFileList;
320 int write_behind_rc;
321 __u32 cifsAttrs; /* e.g. DOS archive bit, sparse, compressed, system */
322 atomic_t inUse; /* num concurrent users (local openers cifs) of file*/
323 unsigned long time; /* jiffies of last update/check of inode */
324 unsigned clientCanCacheRead:1; /* read oplock */
325 unsigned clientCanCacheAll:1; /* read and writebehind oplock */
326 unsigned oplockPending:1;
327 struct inode vfs_inode;
328};
329
330static inline struct cifsInodeInfo *
331CIFS_I(struct inode *inode)
332{
333 return container_of(inode, struct cifsInodeInfo, vfs_inode);
334}
335
336static inline struct cifs_sb_info *
337CIFS_SB(struct super_block *sb)
338{
339 return sb->s_fs_info;
340}
341
Steve Frenchab2f2182005-09-15 20:44:50 -0700342static inline char CIFS_DIR_SEP(const struct cifs_sb_info *cifs_sb)
Jeremy Allisonac670552005-06-22 17:26:35 -0700343{
344 if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_POSIX_PATHS)
345 return '/';
346 else
347 return '\\';
348}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700349
Steve Frencha4544342005-08-24 13:59:35 -0700350#ifdef CONFIG_CIFS_STATS
351#define cifs_stats_inc atomic_inc
352
353static inline void cifs_stats_bytes_written(struct cifsTconInfo *tcon,
354 unsigned int bytes)
355{
356 if (bytes) {
357 spin_lock(&tcon->stat_lock);
358 tcon->bytes_written += bytes;
359 spin_unlock(&tcon->stat_lock);
360 }
361}
362
363static inline void cifs_stats_bytes_read(struct cifsTconInfo *tcon,
364 unsigned int bytes)
365{
366 spin_lock(&tcon->stat_lock);
367 tcon->bytes_read += bytes;
368 spin_unlock(&tcon->stat_lock);
369}
370#else
371
372#define cifs_stats_inc(field) do {} while(0)
373#define cifs_stats_bytes_written(tcon, bytes) do {} while(0)
374#define cifs_stats_bytes_read(tcon, bytes) do {} while(0)
375
376#endif
377
Linus Torvalds1da177e2005-04-16 15:20:36 -0700378/* one of these for every pending CIFS request to the server */
379struct mid_q_entry {
380 struct list_head qhead; /* mids waiting on reply from this server */
381 __u16 mid; /* multiplex id */
382 __u16 pid; /* process id */
383 __u32 sequence_number; /* for CIFS signing */
Steve French1047abc2005-10-11 19:58:06 -0700384 unsigned long when_alloc; /* when mid was created */
385#ifdef CONFIG_CIFS_STATS2
386 unsigned long when_sent; /* time when smb send finished */
387 unsigned long when_received; /* when demux complete (taken off wire) */
388#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -0700389 struct cifsSesInfo *ses; /* smb was sent to this server */
390 struct task_struct *tsk; /* task waiting for response */
391 struct smb_hdr *resp_buf; /* response buffer */
392 int midState; /* wish this were enum but can not pass to wait_event */
Steve Frenchc81156d2005-04-28 22:41:07 -0700393 __u8 command; /* smb command code */
394 unsigned multiPart:1; /* multiple responses to one SMB request */
395 unsigned largeBuf:1; /* if valid response, is pointer to large buf */
Steve French79944bf2005-04-28 22:41:09 -0700396 unsigned multiResp:1; /* multiple trans2 responses for one request */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700397};
398
399struct oplock_q_entry {
400 struct list_head qhead;
401 struct inode * pinode;
402 struct cifsTconInfo * tcon;
403 __u16 netfid;
404};
405
Steve Frenchff5dbd92005-08-24 17:10:36 -0700406/* for pending dnotify requests */
407struct dir_notify_req {
408 struct list_head lhead;
409 __le16 Pid;
410 __le16 PidHigh;
411 __u16 Mid;
412 __u16 Tid;
413 __u16 Uid;
414 __u16 netfid;
415 __u32 filter; /* CompletionFilter (for multishot) */
416 int multishot;
Steve Frenche22cb8b2005-08-24 20:25:21 -0700417 struct file * pfile;
Steve Frenchff5dbd92005-08-24 17:10:36 -0700418};
419
Linus Torvalds1da177e2005-04-16 15:20:36 -0700420#define MID_FREE 0
421#define MID_REQUEST_ALLOCATED 1
422#define MID_REQUEST_SUBMITTED 2
423#define MID_RESPONSE_RECEIVED 4
424#define MID_RETRY_NEEDED 8 /* session closed while this request out */
425#define MID_NO_RESP_NEEDED 0x10
Steve Frenchec637e32005-12-12 20:53:18 -0800426
427/* Types of response buffer returned from SendReceive2 */
428#define CIFS_NO_BUFFER 0 /* Response buffer not returned */
429#define CIFS_SMALL_BUFFER 1
430#define CIFS_LARGE_BUFFER 2
431#define CIFS_IOVEC 4 /* array of response buffers */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700432
433/*
434 *****************************************************************
435 * All constants go here
436 *****************************************************************
437 */
438
439#define UID_HASH (16)
440
441/*
442 * Note that ONE module should define _DECLARE_GLOBALS_HERE to cause the
443 * following to be declared.
444 */
445
446/****************************************************************************
447 * Locking notes. All updates to global variables and lists should be
448 * protected by spinlocks or semaphores.
449 *
450 * Spinlocks
451 * ---------
452 * GlobalMid_Lock protects:
453 * list operations on pending_mid_q and oplockQ
454 * updates to XID counters, multiplex id and SMB sequence numbers
455 * GlobalSMBSesLock protects:
456 * list operations on tcp and SMB session lists and tCon lists
457 * f_owner.lock protects certain per file struct operations
458 * mapping->page_lock protects certain per page operations
459 *
460 * Semaphores
461 * ----------
462 * sesSem operations on smb session
463 * tconSem operations on tree connection
464 * fh_sem file handle reconnection operations
465 *
466 ****************************************************************************/
467
468#ifdef DECLARE_GLOBALS_HERE
469#define GLOBAL_EXTERN
470#else
471#define GLOBAL_EXTERN extern
472#endif
473
474/*
475 * The list of servers that did not respond with NT LM 0.12.
476 * This list helps improve performance and eliminate the messages indicating
477 * that we had a communications error talking to the server in this list.
478 */
479GLOBAL_EXTERN struct servers_not_supported *NotSuppList; /*@z4a */
480
481/*
482 * The following is a hash table of all the users we know about.
483 */
484GLOBAL_EXTERN struct smbUidInfo *GlobalUidList[UID_HASH];
485
486GLOBAL_EXTERN struct list_head GlobalServerList; /* BB not implemented yet */
487GLOBAL_EXTERN struct list_head GlobalSMBSessionList;
488GLOBAL_EXTERN struct list_head GlobalTreeConnectionList;
489GLOBAL_EXTERN rwlock_t GlobalSMBSeslock; /* protects list inserts on 3 above */
490
491GLOBAL_EXTERN struct list_head GlobalOplock_Q;
492
Steve Frenchff5dbd92005-08-24 17:10:36 -0700493GLOBAL_EXTERN struct list_head GlobalDnotifyReqList; /* Outstanding dir notify requests */
494GLOBAL_EXTERN struct list_head GlobalDnotifyRsp_Q; /* Dir notify response queue */
495
Linus Torvalds1da177e2005-04-16 15:20:36 -0700496/*
497 * Global transaction id (XID) information
498 */
499GLOBAL_EXTERN unsigned int GlobalCurrentXid; /* protected by GlobalMid_Sem */
500GLOBAL_EXTERN unsigned int GlobalTotalActiveXid; /* prot by GlobalMid_Sem */
501GLOBAL_EXTERN unsigned int GlobalMaxActiveXid; /* prot by GlobalMid_Sem */
502GLOBAL_EXTERN spinlock_t GlobalMid_Lock; /* protects above and list operations */
503 /* on midQ entries */
504GLOBAL_EXTERN char Local_System_Name[15];
505
506/*
507 * Global counters, updated atomically
508 */
509GLOBAL_EXTERN atomic_t sesInfoAllocCount;
510GLOBAL_EXTERN atomic_t tconInfoAllocCount;
511GLOBAL_EXTERN atomic_t tcpSesAllocCount;
512GLOBAL_EXTERN atomic_t tcpSesReconnectCount;
513GLOBAL_EXTERN atomic_t tconInfoReconnectCount;
514
515/* Various Debug counters to remove someday (BB) */
Steve French4498eed2005-12-03 13:58:57 -0800516GLOBAL_EXTERN atomic_t bufAllocCount; /* current number allocated */
517#ifdef CONFIG_CIFS_STATS2
518GLOBAL_EXTERN atomic_t totBufAllocCount; /* total allocated over all time */
519GLOBAL_EXTERN atomic_t totSmBufAllocCount;
520#endif
521GLOBAL_EXTERN atomic_t smBufAllocCount;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700522GLOBAL_EXTERN atomic_t midCount;
523
524/* Misc globals */
525GLOBAL_EXTERN unsigned int multiuser_mount; /* if enabled allows new sessions
526 to be established on existing mount if we
527 have the uid/password or Kerberos credential
528 or equivalent for current user */
529GLOBAL_EXTERN unsigned int oplockEnabled;
530GLOBAL_EXTERN unsigned int experimEnabled;
531GLOBAL_EXTERN unsigned int lookupCacheEnabled;
532GLOBAL_EXTERN unsigned int extended_security; /* if on, session setup sent
533 with more secure ntlmssp2 challenge/resp */
534GLOBAL_EXTERN unsigned int ntlmv2_support; /* better optional password hash */
535GLOBAL_EXTERN unsigned int sign_CIFS_PDUs; /* enable smb packet signing */
536GLOBAL_EXTERN unsigned int linuxExtEnabled;/*enable Linux/Unix CIFS extensions*/
537GLOBAL_EXTERN unsigned int CIFSMaxBufSize; /* max size not including hdr */
538GLOBAL_EXTERN unsigned int cifs_min_rcv; /* min size of big ntwrk buf pool */
539GLOBAL_EXTERN unsigned int cifs_min_small; /* min size of small buf pool */
540GLOBAL_EXTERN unsigned int cifs_max_pending; /* MAX requests at once to server*/
541