upcall.c

linux 内核源代码

	/* Round up to word boundary and null terminate */
        offset += s;
        inp->coda_symlink.tname = offset;
        s = (len & ~0x3) + 4;
        memcpy((char *)(inp) + offset, name, len);
        *((char *)inp + offset + len) = '\0';

	error = coda_upcall(coda_vcp(sb), insize, &outsize, inp);

	CODA_FREE(inp, insize);
        return error;
}

int venus_fsync(struct super_block *sb, struct CodaFid *fid)
{
        union inputArgs *inp;
        union outputArgs *outp; 
	int insize, outsize, error;
	
	insize=SIZE(fsync);
	UPARG(CODA_FSYNC);

	inp->coda_fsync.VFid = *fid;
	error = coda_upcall(coda_vcp(sb), sizeof(union inputArgs),
			    &outsize, inp);

	CODA_FREE(inp, insize);
	return error;
}

int venus_access(struct super_block *sb, struct CodaFid *fid, int mask)
{
        union inputArgs *inp;
        union outputArgs *outp; 
	int insize, outsize, error;

	insize = SIZE(access);
	UPARG(CODA_ACCESS);

        inp->coda_access.VFid = *fid;
        inp->coda_access.flags = mask;

	error = coda_upcall(coda_vcp(sb), insize, &outsize, inp);

	CODA_FREE(inp, insize);
	return error;
}


int venus_pioctl(struct super_block *sb, struct CodaFid *fid,
		 unsigned int cmd, struct PioctlData *data)
{
        union inputArgs *inp;
        union outputArgs *outp;  
	int insize, outsize, error;
	int iocsize;

	insize = VC_MAXMSGSIZE;
	UPARG(CODA_IOCTL);

        /* build packet for Venus */
        if (data->vi.in_size > VC_MAXDATASIZE) {
		error = -EINVAL;
		goto exit;
        }

        if (data->vi.out_size > VC_MAXDATASIZE) {
		error = -EINVAL;
		goto exit;
	}

        inp->coda_ioctl.VFid = *fid;
    
        /* the cmd field was mutated by increasing its size field to
         * reflect the path and follow args. We need to subtract that
         * out before sending the command to Venus.  */
        inp->coda_ioctl.cmd = (cmd & ~(PIOCPARM_MASK << 16));	
        iocsize = ((cmd >> 16) & PIOCPARM_MASK) - sizeof(char *) - sizeof(int);
        inp->coda_ioctl.cmd |= (iocsize & PIOCPARM_MASK) <<	16;	
    
        /* in->coda_ioctl.rwflag = flag; */
        inp->coda_ioctl.len = data->vi.in_size;
        inp->coda_ioctl.data = (char *)(INSIZE(ioctl));
     
        /* get the data out of user space */
        if ( copy_from_user((char*)inp + (long)inp->coda_ioctl.data,
			    data->vi.in, data->vi.in_size) ) {
		error = -EINVAL;
	        goto exit;
	}

	error = coda_upcall(coda_vcp(sb), SIZE(ioctl) + data->vi.in_size,
			    &outsize, inp);

        if (error) {
	        printk("coda_pioctl: Venus returns: %d for %s\n", 
		       error, coda_f2s(fid));
		goto exit; 
	}

	if (outsize < (long)outp->coda_ioctl.data + outp->coda_ioctl.len) {
		error = -EINVAL;
		goto exit;
	}
        
	/* Copy out the OUT buffer. */
        if (outp->coda_ioctl.len > data->vi.out_size) {
		error = -EINVAL;
		goto exit;
        }

	/* Copy out the OUT buffer. */
	if (copy_to_user(data->vi.out,
			 (char *)outp + (long)outp->coda_ioctl.data,
			 outp->coda_ioctl.len)) {
		error = -EFAULT;
		goto exit;
	}

 exit:
	CODA_FREE(inp, insize);
	return error;
}

int venus_statfs(struct dentry *dentry, struct kstatfs *sfs)
{ 
        union inputArgs *inp;
        union outputArgs *outp;
        int insize, outsize, error;
        
	insize = max_t(unsigned int, INSIZE(statfs), OUTSIZE(statfs));
	UPARG(CODA_STATFS);

	error = coda_upcall(coda_vcp(dentry->d_sb), insize, &outsize, inp);
	if (!error) {
		sfs->f_blocks = outp->coda_statfs.stat.f_blocks;
		sfs->f_bfree  = outp->coda_statfs.stat.f_bfree;
		sfs->f_bavail = outp->coda_statfs.stat.f_bavail;
		sfs->f_files  = outp->coda_statfs.stat.f_files;
		sfs->f_ffree  = outp->coda_statfs.stat.f_ffree;
	}

        CODA_FREE(inp, insize);
        return error;
}

/*
 * coda_upcall and coda_downcall routines.
 */
static void coda_block_signals(sigset_t *old)
{
	spin_lock_irq(&current->sighand->siglock);
	*old = current->blocked;

	sigfillset(&current->blocked);
	sigdelset(&current->blocked, SIGKILL);
	sigdelset(&current->blocked, SIGSTOP);
	sigdelset(&current->blocked, SIGINT);

	recalc_sigpending();
	spin_unlock_irq(&current->sighand->siglock);
}

static void coda_unblock_signals(sigset_t *old)
{
	spin_lock_irq(&current->sighand->siglock);
	current->blocked = *old;
	recalc_sigpending();
	spin_unlock_irq(&current->sighand->siglock);
}

/* Don't allow signals to interrupt the following upcalls before venus
 * has seen them,
 * - CODA_CLOSE or CODA_RELEASE upcall  (to avoid reference count problems)
 * - CODA_STORE				(to avoid data loss)
 */
#define CODA_INTERRUPTIBLE(r) (!coda_hard && \
			       (((r)->uc_opcode != CODA_CLOSE && \
				 (r)->uc_opcode != CODA_STORE && \
				 (r)->uc_opcode != CODA_RELEASE) || \
				(r)->uc_flags & REQ_READ))

static inline void coda_waitfor_upcall(struct upc_req *req)
{
	DECLARE_WAITQUEUE(wait, current);
	unsigned long timeout = jiffies + coda_timeout * HZ;
	sigset_t old;
	int blocked;

	coda_block_signals(&old);
	blocked = 1;

	add_wait_queue(&req->uc_sleep, &wait);
	for (;;) {
		if (CODA_INTERRUPTIBLE(req))
			set_current_state(TASK_INTERRUPTIBLE);
		else
			set_current_state(TASK_UNINTERRUPTIBLE);

		/* got a reply */
		if (req->uc_flags & (REQ_WRITE | REQ_ABORT))
			break;

		if (blocked && time_after(jiffies, timeout) &&
		    CODA_INTERRUPTIBLE(req))
		{
			coda_unblock_signals(&old);
			blocked = 0;
		}

		if (signal_pending(current)) {
			list_del(&req->uc_chain);
			break;
		}

		if (blocked)
			schedule_timeout(HZ);
		else
			schedule();
	}
	if (blocked)
		coda_unblock_signals(&old);

	remove_wait_queue(&req->uc_sleep, &wait);
	set_current_state(TASK_RUNNING);
}


/*
 * coda_upcall will return an error in the case of
 * failed communication with Venus _or_ will peek at Venus
 * reply and return Venus' error.
 *
 * As venus has 2 types of errors, normal errors (positive) and internal
 * errors (negative), normal errors are negated, while internal errors
 * are all mapped to -EINTR, while showing a nice warning message. (jh)
 */
static int coda_upcall(struct venus_comm *vcp,
		       int inSize, int *outSize,
		       union inputArgs *buffer)
{
	union outputArgs *out;
	union inputArgs *sig_inputArgs;
	struct upc_req *req, *sig_req;
	int error = 0;

	if (!vcp->vc_inuse) {
		printk(KERN_NOTICE "coda: Venus dead, not sending upcall\n");
		return -ENXIO;
	}

	/* Format the request message. */
	req = kmalloc(sizeof(struct upc_req), GFP_KERNEL);
	if (!req)
		return -ENOMEM;

	req->uc_data = (void *)buffer;
	req->uc_flags = 0;
	req->uc_inSize = inSize;
	req->uc_outSize = *outSize ? *outSize : inSize;
	req->uc_opcode = ((union inputArgs *)buffer)->ih.opcode;
	req->uc_unique = ++vcp->vc_seq;
	init_waitqueue_head(&req->uc_sleep);

	/* Fill in the common input args. */
	((union inputArgs *)buffer)->ih.unique = req->uc_unique;

	/* Append msg to pending queue and poke Venus. */
	list_add_tail(&req->uc_chain, &vcp->vc_pending);

	wake_up_interruptible(&vcp->vc_waitq);
	/* We can be interrupted while we wait for Venus to process
	 * our request.  If the interrupt occurs before Venus has read
	 * the request, we dequeue and return. If it occurs after the
	 * read but before the reply, we dequeue, send a signal
	 * message, and return. If it occurs after the reply we ignore
	 * it. In no case do we want to restart the syscall.  If it
	 * was interrupted by a venus shutdown (psdev_close), return
	 * ENODEV.  */

	/* Go to sleep.  Wake up on signals only after the timeout. */
	coda_waitfor_upcall(req);

	/* Op went through, interrupt or not... */
	if (req->uc_flags & REQ_WRITE) {
		out = (union outputArgs *)req->uc_data;
		/* here we map positive Venus errors to kernel errors */
		error = -out->oh.result;
		*outSize = req->uc_outSize;
		goto exit;
	}

	error = -EINTR;
	if ((req->uc_flags & REQ_ABORT) || !signal_pending(current)) {
		printk(KERN_WARNING "coda: Unexpected interruption.\n");
		goto exit;
	}

	/* Interrupted before venus read it. */
	if (!(req->uc_flags & REQ_READ))
		goto exit;

	/* Venus saw the upcall, make sure we can send interrupt signal */
	if (!vcp->vc_inuse) {
		printk(KERN_INFO "coda: Venus dead, not sending signal.\n");
		goto exit;
	}

	error = -ENOMEM;
	sig_req = kmalloc(sizeof(struct upc_req), GFP_KERNEL);
	if (!sig_req) goto exit;

	CODA_ALLOC((sig_req->uc_data), char *, sizeof(struct coda_in_hdr));
	if (!sig_req->uc_data) {
		kfree(sig_req);
		goto exit;
	}

	error = -EINTR;
	sig_inputArgs = (union inputArgs *)sig_req->uc_data;
	sig_inputArgs->ih.opcode = CODA_SIGNAL;
	sig_inputArgs->ih.unique = req->uc_unique;

	sig_req->uc_flags = REQ_ASYNC;
	sig_req->uc_opcode = sig_inputArgs->ih.opcode;
	sig_req->uc_unique = sig_inputArgs->ih.unique;
	sig_req->uc_inSize = sizeof(struct coda_in_hdr);
	sig_req->uc_outSize = sizeof(struct coda_in_hdr);

	/* insert at head of queue! */
	list_add(&(sig_req->uc_chain), &vcp->vc_pending);
	wake_up_interruptible(&vcp->vc_waitq);

exit:
	kfree(req);
	return error;
}

/*  
    The statements below are part of the Coda opportunistic
    programming -- taken from the Mach/BSD kernel code for Coda. 
    You don't get correct semantics by stating what needs to be
    done without guaranteeing the invariants needed for it to happen.
    When will be have time to find out what exactly is going on?  (pjb)
*/


/* 
 * There are 7 cases where cache invalidations occur.  The semantics
 *  of each is listed here:
 *
 * CODA_FLUSH     -- flush all entries from the name cache and the cnode cache.
 * CODA_PURGEUSER -- flush all entries from the name cache for a specific user
 *                  This call is a result of token expiration.
 *
 * The next arise as the result of callbacks on a file or directory.
 * CODA_ZAPFILE   -- flush the cached attributes for a file.

 * CODA_ZAPDIR    -- flush the attributes for the dir and
 *                  force a new lookup for all the children
                    of this dir.

 *
 * The next is a result of Venus detecting an inconsistent file.
 * CODA_PURGEFID  -- flush the attribute for the file
 *                  purge it and its children from the dcache
 *
 * The last  allows Venus to replace local fids with global ones
 * during reintegration.
 *
 * CODA_REPLACE -- replace one CodaFid with another throughout the name cache */

int coda_downcall(int opcode, union outputArgs * out, struct super_block *sb)
{
	struct inode *inode = NULL;
	struct CodaFid *fid, *newfid;

	/* Handle invalidation requests. */
	if ( !sb || !sb->s_root)
		return 0;

	switch (opcode) {
	case CODA_FLUSH:
		coda_cache_clear_all(sb);
		shrink_dcache_sb(sb);
		if (sb->s_root->d_inode)
		    coda_flag_inode(sb->s_root->d_inode, C_FLUSH);
		break;

	case CODA_PURGEUSER:
		coda_cache_clear_all(sb);
		break;

	case CODA_ZAPDIR:
		fid = &out->coda_zapdir.CodaFid;
		inode = coda_fid_to_inode(fid, sb);
		if (inode) {
			coda_flag_inode_children(inode, C_PURGE);
			coda_flag_inode(inode, C_VATTR);
		}
		break;

	case CODA_ZAPFILE:
		fid = &out->coda_zapfile.CodaFid;
		inode = coda_fid_to_inode(fid, sb);
		if (inode)
			coda_flag_inode(inode, C_VATTR);
		break;

	case CODA_PURGEFID:
		fid = &out->coda_purgefid.CodaFid;
		inode = coda_fid_to_inode(fid, sb);
		if (inode) {
			coda_flag_inode_children(inode, C_PURGE);

			/* catch the dentries later if some are still busy */
			coda_flag_inode(inode, C_PURGE);
			d_prune_aliases(inode);

		}
		break;

	case CODA_REPLACE:
		fid = &out->coda_replace.OldFid;
		newfid = &out->coda_replace.NewFid;
		inode = coda_fid_to_inode(fid, sb);
		if (inode)
			coda_replace_fid(inode, fid, newfid);
		break;
	}

	if (inode)
		iput(inode);

	return 0;
}