diff --git a/fs/coda/inode.c b/fs/coda/inode.c
index b7fa3e3..7993b96 100644
--- a/fs/coda/inode.c
+++ b/fs/coda/inode.c
@@ -15,7 +15,7 @@
 #include <linux/stat.h>
 #include <linux/errno.h>
 #include <linux/unistd.h>
-#include <linux/smp_lock.h>
+#include <linux/mutex.h>
 #include <linux/spinlock.h>
 #include <linux/file.h>
 #include <linux/vfs.h>
@@ -145,7 +145,7 @@
 static int coda_fill_super(struct super_block *sb, void *data, int silent)
 {
 	struct inode *root = NULL;
-	struct venus_comm *vc = NULL;
+	struct venus_comm *vc;
 	struct CodaFid fid;
 	int error;
 	int idx;
@@ -159,7 +159,7 @@
 	printk(KERN_INFO "coda_read_super: device index: %i\n", idx);
 
 	vc = &coda_comms[idx];
-	lock_kernel();
+	mutex_lock(&vc->vc_mutex);
 
 	if (!vc->vc_inuse) {
 		printk("coda_read_super: No pseudo device\n");
@@ -178,7 +178,7 @@
 		goto unlock_out;
 
 	vc->vc_sb = sb;
-	unlock_kernel();
+	mutex_unlock(&vc->vc_mutex);
 
 	sb->s_fs_info = vc;
 	sb->s_flags |= MS_NOATIME;
@@ -217,20 +217,23 @@
 	if (root)
 		iput(root);
 
-	lock_kernel();
+	mutex_lock(&vc->vc_mutex);
 	bdi_destroy(&vc->bdi);
 	vc->vc_sb = NULL;
 	sb->s_fs_info = NULL;
 unlock_out:
-	unlock_kernel();
+	mutex_unlock(&vc->vc_mutex);
 	return error;
 }
 
 static void coda_put_super(struct super_block *sb)
 {
-	bdi_destroy(&coda_vcp(sb)->bdi);
-	coda_vcp(sb)->vc_sb = NULL;
+	struct venus_comm *vcp = coda_vcp(sb);
+	mutex_lock(&vcp->vc_mutex);
+	bdi_destroy(&vcp->bdi);
+	vcp->vc_sb = NULL;
 	sb->s_fs_info = NULL;
+	mutex_unlock(&vcp->vc_mutex);
 
 	printk("Coda: Bye bye.\n");
 }
diff --git a/fs/coda/psdev.c b/fs/coda/psdev.c
index 9a9248e..62647a8 100644
--- a/fs/coda/psdev.c
+++ b/fs/coda/psdev.c
@@ -35,7 +35,7 @@
 #include <linux/poll.h>
 #include <linux/init.h>
 #include <linux/list.h>
-#include <linux/smp_lock.h>
+#include <linux/mutex.h>
 #include <linux/device.h>
 #include <asm/io.h>
 #include <asm/system.h>
@@ -67,8 +67,10 @@
 	unsigned int mask = POLLOUT | POLLWRNORM;
 
 	poll_wait(file, &vcp->vc_waitq, wait);
+	mutex_lock(&vcp->vc_mutex);
 	if (!list_empty(&vcp->vc_pending))
                 mask |= POLLIN | POLLRDNORM;
+	mutex_unlock(&vcp->vc_mutex);
 
 	return mask;
 }
@@ -143,7 +145,7 @@
 	}
         
 	/* Look for the message on the processing queue. */
-	lock_kernel();
+	mutex_lock(&vcp->vc_mutex);
 	list_for_each(lh, &vcp->vc_processing) {
 		tmp = list_entry(lh, struct upc_req , uc_chain);
 		if (tmp->uc_unique == hdr.unique) {
@@ -152,7 +154,7 @@
 			break;
 		}
 	}
-	unlock_kernel();
+	mutex_unlock(&vcp->vc_mutex);
 
 	if (!req) {
 		printk("psdev_write: msg (%d, %d) not found\n", 
@@ -207,7 +209,7 @@
 	if (nbytes == 0)
 		return 0;
 
-	lock_kernel();
+	mutex_lock(&vcp->vc_mutex);
 
 	add_wait_queue(&vcp->vc_waitq, &wait);
 	set_current_state(TASK_INTERRUPTIBLE);
@@ -221,7 +223,9 @@
 			retval = -ERESTARTSYS;
 			break;
 		}
+		mutex_unlock(&vcp->vc_mutex);
 		schedule();
+		mutex_lock(&vcp->vc_mutex);
 	}
 
 	set_current_state(TASK_RUNNING);
@@ -254,7 +258,7 @@
 	CODA_FREE(req->uc_data, sizeof(struct coda_in_hdr));
 	kfree(req);
 out:
-	unlock_kernel();
+	mutex_unlock(&vcp->vc_mutex);
 	return (count ? count : retval);
 }
 
@@ -267,10 +271,10 @@
 	if (idx < 0 || idx >= MAX_CODADEVS)
 		return -ENODEV;
 
-	lock_kernel();
-
 	err = -EBUSY;
 	vcp = &coda_comms[idx];
+	mutex_lock(&vcp->vc_mutex);
+
 	if (!vcp->vc_inuse) {
 		vcp->vc_inuse++;
 
@@ -284,7 +288,7 @@
 		err = 0;
 	}
 
-	unlock_kernel();
+	mutex_unlock(&vcp->vc_mutex);
 	return err;
 }
 
@@ -299,7 +303,7 @@
 		return -1;
 	}
 
-	lock_kernel();
+	mutex_lock(&vcp->vc_mutex);
 
 	/* Wakeup clients so they can return. */
 	list_for_each_entry_safe(req, tmp, &vcp->vc_pending, uc_chain) {
@@ -324,7 +328,7 @@
 
 	file->private_data = NULL;
 	vcp->vc_inuse--;
-	unlock_kernel();
+	mutex_unlock(&vcp->vc_mutex);
 	return 0;
 }
 
@@ -353,9 +357,11 @@
 		err = PTR_ERR(coda_psdev_class);
 		goto out_chrdev;
 	}		
-	for (i = 0; i < MAX_CODADEVS; i++)
+	for (i = 0; i < MAX_CODADEVS; i++) {
+		mutex_init(&(&coda_comms[i])->vc_mutex);
 		device_create(coda_psdev_class, NULL,
 			      MKDEV(CODA_PSDEV_MAJOR, i), NULL, "cfs%d", i);
+	}
 	coda_sysctl_init();
 	goto out;
 
diff --git a/fs/coda/upcall.c b/fs/coda/upcall.c
index 4c258cb..c3563ca 100644
--- a/fs/coda/upcall.c
+++ b/fs/coda/upcall.c
@@ -27,7 +27,7 @@
 #include <linux/errno.h>
 #include <linux/string.h>
 #include <linux/slab.h>
-#include <linux/smp_lock.h>
+#include <linux/mutex.h>
 #include <asm/uaccess.h>
 #include <linux/vmalloc.h>
 #include <linux/vfs.h>
@@ -607,7 +607,8 @@
 				 (r)->uc_opcode != CODA_RELEASE) || \
 				(r)->uc_flags & CODA_REQ_READ))
 
-static inline void coda_waitfor_upcall(struct upc_req *req)
+static inline void coda_waitfor_upcall(struct venus_comm *vcp,
+				       struct upc_req *req)
 {
 	DECLARE_WAITQUEUE(wait, current);
 	unsigned long timeout = jiffies + coda_timeout * HZ;
@@ -640,10 +641,12 @@
 			break;
 		}
 
+		mutex_unlock(&vcp->vc_mutex);
 		if (blocked)
 			schedule_timeout(HZ);
 		else
 			schedule();
+		mutex_lock(&vcp->vc_mutex);
 	}
 	if (blocked)
 		coda_unblock_signals(&old);
@@ -671,7 +674,7 @@
 	struct upc_req *req = NULL, *sig_req;
 	int error;
 
-	lock_kernel();
+	mutex_lock(&vcp->vc_mutex);
 
 	if (!vcp->vc_inuse) {
 		printk(KERN_NOTICE "coda: Venus dead, not sending upcall\n");
@@ -711,7 +714,7 @@
 	 * ENODEV.  */
 
 	/* Go to sleep.  Wake up on signals only after the timeout. */
-	coda_waitfor_upcall(req);
+	coda_waitfor_upcall(vcp, req);
 
 	/* Op went through, interrupt or not... */
 	if (req->uc_flags & CODA_REQ_WRITE) {
@@ -765,7 +768,7 @@
 
 exit:
 	kfree(req);
-	unlock_kernel();
+	mutex_unlock(&vcp->vc_mutex);
 	return error;
 }
 
@@ -806,11 +809,11 @@
 int coda_downcall(struct venus_comm *vcp, int opcode, union outputArgs *out)
 {
 	struct inode *inode = NULL;
-	struct CodaFid *fid, *newfid;
+	struct CodaFid *fid = NULL, *newfid;
 	struct super_block *sb;
 
 	/* Handle invalidation requests. */
-	lock_kernel();
+	mutex_lock(&vcp->vc_mutex);
 	sb = vcp->vc_sb;
 	if (!sb || !sb->s_root)
 		goto unlock_out;
@@ -829,47 +832,53 @@
 
 	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 (fid)
+		inode = coda_fid_to_inode(fid, sb);
 
 unlock_out:
-	unlock_kernel();
+	mutex_unlock(&vcp->vc_mutex);
 
-	if (inode)
-		iput(inode);
+	if (!inode)
+		return 0;
+
+	switch (opcode) {
+	case CODA_ZAPDIR:
+		coda_flag_inode_children(inode, C_PURGE);
+		coda_flag_inode(inode, C_VATTR);
+		break;
+
+	case CODA_ZAPFILE:
+		coda_flag_inode(inode, C_VATTR);
+		break;
+
+	case CODA_PURGEFID:
+		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:
+		newfid = &out->coda_replace.NewFid;
+		coda_replace_fid(inode, fid, newfid);
+		break;
+	}
+	iput(inode);
 	return 0;
 }