From 88257360605f9362dc4d79326c268dd334f61c90 Mon Sep 17 00:00:00 2001 From: Pavel Shilovsky Date: Wed, 23 May 2012 14:01:59 +0400 Subject: CIFS: Move get_next_mid to ops struct Reviewed-by: Jeff Layton Signed-off-by: Pavel Shilovsky Signed-off-by: Steve French --- fs/cifs/misc.c | 89 +--------------------------------------------------------- 1 file changed, 1 insertion(+), 88 deletions(-) (limited to 'fs/cifs/misc.c') diff --git a/fs/cifs/misc.c b/fs/cifs/misc.c index e2552d2b2e42..557506ae1e2a 100644 --- a/fs/cifs/misc.c +++ b/fs/cifs/misc.c @@ -212,93 +212,6 @@ cifs_small_buf_release(void *buf_to_free) return; } -/* - * Find a free multiplex id (SMB mid). Otherwise there could be - * mid collisions which might cause problems, demultiplexing the - * wrong response to this request. Multiplex ids could collide if - * one of a series requests takes much longer than the others, or - * if a very large number of long lived requests (byte range - * locks or FindNotify requests) are pending. No more than - * 64K-1 requests can be outstanding at one time. If no - * mids are available, return zero. A future optimization - * could make the combination of mids and uid the key we use - * to demultiplex on (rather than mid alone). - * In addition to the above check, the cifs demultiplex - * code already used the command code as a secondary - * check of the frame and if signing is negotiated the - * response would be discarded if the mid were the same - * but the signature was wrong. Since the mid is not put in the - * pending queue until later (when it is about to be dispatched) - * we do have to limit the number of outstanding requests - * to somewhat less than 64K-1 although it is hard to imagine - * so many threads being in the vfs at one time. - */ -__u64 GetNextMid(struct TCP_Server_Info *server) -{ - __u64 mid = 0; - __u16 last_mid, cur_mid; - bool collision; - - spin_lock(&GlobalMid_Lock); - - /* mid is 16 bit only for CIFS/SMB */ - cur_mid = (__u16)((server->CurrentMid) & 0xffff); - /* we do not want to loop forever */ - last_mid = cur_mid; - cur_mid++; - - /* - * This nested loop looks more expensive than it is. - * In practice the list of pending requests is short, - * fewer than 50, and the mids are likely to be unique - * on the first pass through the loop unless some request - * takes longer than the 64 thousand requests before it - * (and it would also have to have been a request that - * did not time out). - */ - while (cur_mid != last_mid) { - struct mid_q_entry *mid_entry; - unsigned int num_mids; - - collision = false; - if (cur_mid == 0) - cur_mid++; - - num_mids = 0; - list_for_each_entry(mid_entry, &server->pending_mid_q, qhead) { - ++num_mids; - if (mid_entry->mid == cur_mid && - mid_entry->mid_state == MID_REQUEST_SUBMITTED) { - /* This mid is in use, try a different one */ - collision = true; - break; - } - } - - /* - * if we have more than 32k mids in the list, then something - * is very wrong. Possibly a local user is trying to DoS the - * box by issuing long-running calls and SIGKILL'ing them. If - * we get to 2^16 mids then we're in big trouble as this - * function could loop forever. - * - * Go ahead and assign out the mid in this situation, but force - * an eventual reconnect to clean out the pending_mid_q. - */ - if (num_mids > 32768) - server->tcpStatus = CifsNeedReconnect; - - if (!collision) { - mid = (__u64)cur_mid; - server->CurrentMid = mid; - break; - } - cur_mid++; - } - spin_unlock(&GlobalMid_Lock); - return mid; -} - /* NB: MID can not be set if treeCon not passed in, in that case it is responsbility of caller to set the mid */ void @@ -334,7 +247,7 @@ header_assemble(struct smb_hdr *buffer, char smb_command /* command */ , /* Uid is not converted */ buffer->Uid = treeCon->ses->Suid; - buffer->Mid = GetNextMid(treeCon->ses->server); + buffer->Mid = get_next_mid(treeCon->ses->server); } if (treeCon->Flags & SMB_SHARE_IS_IN_DFS) buffer->Flags2 |= SMBFLG2_DFS; -- cgit