oplock.c

来自「samba-3.0.22.tar.gz 编译smb服务器的源码」· C语言 代码 · 共 894 行 · 第 1/2 页

/* 
   Unix SMB/CIFS implementation.
   oplock processing
   Copyright (C) Andrew Tridgell 1992-1998
   Copyright (C) Jeremy Allison 1998 - 2001
   Copyright (C) Volker Lendecke 2005
   
   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 2 of the License, or
   (at your option) any later version.
   
   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.
   
   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/

#include "includes.h"

/* Current number of oplocks we have outstanding. */
static int32 exclusive_oplocks_open = 0;
static int32 level_II_oplocks_open = 0;
BOOL global_client_failed_oplock_break = False;

extern struct timeval smb_last_time;
extern uint32 global_client_caps;
extern int smb_read_error;

static struct kernel_oplocks *koplocks;

/****************************************************************************
 Get the number of current exclusive oplocks.
****************************************************************************/

int32 get_number_of_exclusive_open_oplocks(void)
{
  return exclusive_oplocks_open;
}

/****************************************************************************
 Return True if an oplock message is pending.
****************************************************************************/

BOOL oplock_message_waiting(fd_set *fds)
{
	if (koplocks && koplocks->msg_waiting(fds)) {
		return True;
	}

	return False;
}

/****************************************************************************
 Find out if there are any kernel oplock messages waiting and process them
 if so. pfds is the fd_set from the main select loop (which contains any
 kernel oplock fd if that's what the system uses (IRIX). If may be NULL if
 we're calling this in a shutting down state.
****************************************************************************/

void process_kernel_oplocks(fd_set *pfds)
{
	/*
	 * We need to check for kernel oplocks before going into the select
	 * here, as the EINTR generated by the linux kernel oplock may have
	 * already been eaten. JRA.
	 */

	if (!koplocks) {
		return;
	}

	while (koplocks->msg_waiting(pfds)) { 
		files_struct *fsp;
		char msg[MSG_SMB_KERNEL_BREAK_SIZE];

		fsp = koplocks->receive_message(pfds);

		if (fsp == NULL) {
			DEBUG(3, ("Kernel oplock message announced, but none "
				  "received\n"));
			return;
		}

		/* Put the kernel break info into the message. */
		SDEV_T_VAL(msg,0,fsp->dev);
		SINO_T_VAL(msg,8,fsp->inode);
		SIVAL(msg,16,fsp->file_id);

		/* Don't need to be root here as we're only ever
		   sending to ourselves. */

		message_send_pid(pid_to_procid(sys_getpid()),
				 MSG_SMB_KERNEL_BREAK,
				 &msg, MSG_SMB_KERNEL_BREAK_SIZE, True);
	}
}

/****************************************************************************
 Attempt to set an oplock on a file. Always succeeds if kernel oplocks are
 disabled (just sets flags). Returns True if oplock set.
****************************************************************************/

BOOL set_file_oplock(files_struct *fsp, int oplock_type)
{
	if (koplocks && !koplocks->set_oplock(fsp, oplock_type)) {
		return False;
	}

	fsp->oplock_type = oplock_type;
	fsp->sent_oplock_break = NO_BREAK_SENT;
	if (oplock_type == LEVEL_II_OPLOCK) {
		level_II_oplocks_open++;
	} else {
		exclusive_oplocks_open++;
	}

	DEBUG(5,("set_file_oplock: granted oplock on file %s, dev = %x, inode = %.0f, file_id = %lu, \
tv_sec = %x, tv_usec = %x\n",
		 fsp->fsp_name, (unsigned int)fsp->dev, (double)fsp->inode, fsp->file_id,
		 (int)fsp->open_time.tv_sec, (int)fsp->open_time.tv_usec ));

	return True;
}

/****************************************************************************
 Attempt to release an oplock on a file. Decrements oplock count.
****************************************************************************/

void release_file_oplock(files_struct *fsp)
{
	if ((fsp->oplock_type != NO_OPLOCK) &&
	    (fsp->oplock_type != FAKE_LEVEL_II_OPLOCK) &&
	    koplocks) {
		koplocks->release_oplock(fsp);
	}

	if (fsp->oplock_type == LEVEL_II_OPLOCK) {
		level_II_oplocks_open--;
	} else if (EXCLUSIVE_OPLOCK_TYPE(fsp->oplock_type)) {
		exclusive_oplocks_open--;
	}

	SMB_ASSERT(exclusive_oplocks_open>=0);
	SMB_ASSERT(level_II_oplocks_open>=0);
	
	fsp->oplock_type = NO_OPLOCK;
	fsp->sent_oplock_break = NO_BREAK_SENT;
	
	flush_write_cache(fsp, OPLOCK_RELEASE_FLUSH);
}

/****************************************************************************
 Attempt to downgrade an oplock on a file. Doesn't decrement oplock count.
****************************************************************************/

static void downgrade_file_oplock(files_struct *fsp)
{
	if (koplocks) {
		koplocks->release_oplock(fsp);
	}
	fsp->oplock_type = LEVEL_II_OPLOCK;
	exclusive_oplocks_open--;
	level_II_oplocks_open++;
	fsp->sent_oplock_break = NO_BREAK_SENT;
}

/****************************************************************************
 Remove a file oplock. Copes with level II and exclusive.
 Locks then unlocks the share mode lock. Client can decide to go directly
 to none even if a "break-to-level II" was sent.
****************************************************************************/

BOOL remove_oplock(files_struct *fsp)
{
	SMB_DEV_T dev = fsp->dev;
	SMB_INO_T inode = fsp->inode;
	BOOL ret;
	struct share_mode_lock *lck;

	/* Remove the oplock flag from the sharemode. */
	lck = get_share_mode_lock(NULL, fsp->dev, fsp->inode, NULL, NULL);
	if (lck == NULL) {
		DEBUG(0,("remove_oplock: failed to lock share entry for "
			 "file %s\n", fsp->fsp_name ));
		return False;
	}
	ret = remove_share_oplock(lck, fsp);
	if (!ret) {
		DEBUG(0,("remove_oplock: failed to remove share oplock for "
			 "file %s fnum %d, dev = %x, inode = %.0f\n",
			 fsp->fsp_name, fsp->fnum, (unsigned int)dev,
			 (double)inode));
	}
	release_file_oplock(fsp);
	talloc_free(lck);
	return ret;
}

/*
 * Deal with a reply when a break-to-level II was sent.
 */
BOOL downgrade_oplock(files_struct *fsp)
{
	SMB_DEV_T dev = fsp->dev;
	SMB_INO_T inode = fsp->inode;
	BOOL ret;
	struct share_mode_lock *lck;

	lck = get_share_mode_lock(NULL, fsp->dev, fsp->inode, NULL, NULL);
	if (lck == NULL) {
		DEBUG(0,("downgrade_oplock: failed to lock share entry for "
			 "file %s\n", fsp->fsp_name ));
		return False;
	}
	ret = downgrade_share_oplock(lck, fsp);
	if (!ret) {
		DEBUG(0,("downgrade_oplock: failed to downgrade share oplock "
			 "for file %s fnum %d, dev = %x, inode = %.0f\n",
			 fsp->fsp_name, fsp->fnum, (unsigned int)dev,
			 (double)inode));
	}

	downgrade_file_oplock(fsp);
	talloc_free(lck);
	return ret;
}

/****************************************************************************
 Setup the listening set of file descriptors for an oplock break
 message either from the UDP socket or from the kernel. Returns the maximum
 fd used.
****************************************************************************/

int setup_oplock_select_set( fd_set *fds)
{
	int maxfd = 0;

	if (koplocks && koplocks->notification_fd != -1) {
		FD_SET(koplocks->notification_fd, fds);
		maxfd = MAX(maxfd, koplocks->notification_fd);
	}

	return maxfd;
}

/****************************************************************************
 Set up an oplock break message.
****************************************************************************/

static char *new_break_smb_message(TALLOC_CTX *mem_ctx,
				   files_struct *fsp, uint8 cmd)
{
	char *result = TALLOC_ARRAY(mem_ctx, char, smb_size + 8*2 + 0);

	if (result == NULL) {
		DEBUG(0, ("talloc failed\n"));
		return NULL;
	}

	memset(result,'\0',smb_size);
	set_message(result,8,0,True);
	SCVAL(result,smb_com,SMBlockingX);
	SSVAL(result,smb_tid,fsp->conn->cnum);
	SSVAL(result,smb_pid,0xFFFF);
	SSVAL(result,smb_uid,0);
	SSVAL(result,smb_mid,0xFFFF);
	SCVAL(result,smb_vwv0,0xFF);
	SSVAL(result,smb_vwv2,fsp->fnum);
	SCVAL(result,smb_vwv3,LOCKING_ANDX_OPLOCK_RELEASE);
	SCVAL(result,smb_vwv3+1,cmd);
	return result;
}

/****************************************************************************
 Function to do the waiting before sending a local break.
****************************************************************************/

static void wait_before_sending_break(void)
{
	struct timeval cur_tv;
	long wait_left = (long)lp_oplock_break_wait_time();

	if (wait_left == 0) {
		return;
	}

	GetTimeOfDay(&cur_tv);

	wait_left -= ((cur_tv.tv_sec - smb_last_time.tv_sec)*1000) +
                ((cur_tv.tv_usec - smb_last_time.tv_usec)/1000);

	if(wait_left > 0) {
		wait_left = MIN(wait_left, 1000);
		sys_usleep(wait_left * 1000);
	}
}

/****************************************************************************
 Ensure that we have a valid oplock.
****************************************************************************/

static files_struct *initial_break_processing(SMB_DEV_T dev, SMB_INO_T inode, unsigned long file_id)
{
	files_struct *fsp = NULL;

	if( DEBUGLVL( 3 ) ) {
		dbgtext( "initial_break_processing: called for dev = 0x%x, inode = %.0f file_id = %lu\n",
			(unsigned int)dev, (double)inode, file_id);
		dbgtext( "Current oplocks_open (exclusive = %d, levelII = %d)\n",
			exclusive_oplocks_open, level_II_oplocks_open );
	}

	/*
	 * We need to search the file open table for the
	 * entry containing this dev and inode, and ensure
	 * we have an oplock on it.
	 */

	fsp = file_find_dif(dev, inode, file_id);

	if(fsp == NULL) {
		/* The file could have been closed in the meantime - return success. */
		if( DEBUGLVL( 3 ) ) {
			dbgtext( "initial_break_processing: cannot find open file with " );
			dbgtext( "dev = 0x%x, inode = %.0f file_id = %lu", (unsigned int)dev,
				(double)inode, file_id);
			dbgtext( "allowing break to succeed.\n" );
		}
		return NULL;
	}

	/* Ensure we have an oplock on the file */

	/*
	 * There is a potential race condition in that an oplock could
	 * have been broken due to another udp request, and yet there are
	 * still oplock break messages being sent in the udp message
	 * queue for this file. So return true if we don't have an oplock,
	 * as we may have just freed it.
	 */

	if(fsp->oplock_type == NO_OPLOCK) {
		if( DEBUGLVL( 3 ) ) {
			dbgtext( "initial_break_processing: file %s ", fsp->fsp_name );
			dbgtext( "(dev = %x, inode = %.0f, file_id = %lu) has no oplock.\n",
				(unsigned int)dev, (double)inode, fsp->file_id );
			dbgtext( "Allowing break to succeed regardless.\n" );
		}
		return NULL;
	}

	return fsp;
}

static void oplock_timeout_handler(struct timed_event *te,
				   const struct timeval *now,
				   void *private_data)
{
	files_struct *fsp = private_data;

	DEBUG(0, ("Oplock break failed for file %s -- replying anyway\n", fsp->fsp_name));
	global_client_failed_oplock_break = True;
	remove_oplock(fsp);
	reply_to_oplock_break_requests(fsp);
}

/*******************************************************************
 Add a timeout handler waiting for the client reply.
*******************************************************************/

static void add_oplock_timeout_handler(files_struct *fsp)
{
	if (fsp->oplock_timeout != NULL) {
		DEBUG(0, ("Logic problem -- have an oplock event hanging "
			  "around\n"));
	}

	fsp->oplock_timeout =
		add_timed_event(NULL,
				timeval_current_ofs(OPLOCK_BREAK_TIMEOUT, 0),
				"oplock_timeout_handler",
				oplock_timeout_handler, fsp);

	if (fsp->oplock_timeout == NULL) {
		DEBUG(0, ("Could not add oplock timeout handler\n"));
	}
}

/*******************************************************************
 This handles the case of a write triggering a break to none
 message on a level2 oplock.
 When we get this message we may be in any of three states :
 NO_OPLOCK, LEVEL_II, FAKE_LEVEL2. We only send a message to
 the client for LEVEL2.
*******************************************************************/

static void process_oplock_async_level2_break_message(int msg_type, struct process_id src,
					 void *buf, size_t len)
{
	struct share_mode_entry msg;
	files_struct *fsp;
	char *break_msg;
	BOOL sign_state;

	if (buf == NULL) {
		DEBUG(0, ("Got NULL buffer\n"));
		return;
	}

	if (len != MSG_SMB_SHARE_MODE_ENTRY_SIZE) {
		DEBUG(0, ("Got invalid msg len %d\n", (int)len));
		return;
	}

	/* De-linearize incoming message. */
	message_to_share_mode_entry(&msg, buf);

	DEBUG(10, ("Got oplock async level 2 break message from pid %d: 0x%x/%.0f/%d\n",
		   (int)procid_to_pid(&src), (unsigned int)msg.dev, (double)msg.inode,
		   (int)msg.share_file_id));

	fsp = initial_break_processing(msg.dev, msg.inode,
				       msg.share_file_id);

	if (fsp == NULL) {
		/* We hit a race here. Break messages are sent, and before we
		 * get to process this message, we have closed the file. 
		 * No need to reply as this is an async message. */
		DEBUG(3, ("process_oplock_async_level2_break_message: Did not find fsp, ignoring\n"));
		return;
	}

	if (fsp->oplock_type == NO_OPLOCK) {
		/* We already got a "break to none" message and we've handled it.
		 * just ignore. */
		DEBUG(3, ("process_oplock_async_level2_break_message: already broken to none, ignoring.\n"));
		return;
	}

	if (fsp->oplock_type == FAKE_LEVEL_II_OPLOCK) {
		/* Don't tell the client, just downgrade. */
		DEBUG(3, ("process_oplock_async_level2_break_message: downgrading fake level 2 oplock.\n"));