1999-01-27 Roland McGrath <roland@baalperazim.frob.com>

	* storeio.c (options): New option -c/--no-cache.
	(inhibit_cache): New variable.
	(parse_opt): Make -c set it.
	(trivfs_append_args): Report --no-cache if set.
	(check_open_hook): Pass inhibit_cache flag to dev_open.
	* dev.h (struct dev): New member `inhibit_cache'.
	(dev_open): Update decl.
	* dev.c (dev_open): Take new arg inhibit_cache, store in new dev.
	If set, don't initialize buf_offs, io_lock, pager, pager_lock.
	(dev_read, dev_write): If DEV->inhibit_cache is set, allow only
	whole-block i/o: EINVAL for non-whole-block attempts.
	* pager.c (dev_get_memory_object): If DEV->inhibit_cache is set, don't
	make our own pager; if store_map returns EOPNOTSUPP, so do we.

4 files changed, 91 insertions, 30 deletions

diff --git a/storeio/dev.c b/storeio/dev.c
index 2f81f32a..30828556 100644
--- a/storeio/dev.c
+++ b/storeio/dev.c
@@ -1,6 +1,6 @@
 /* store `device' I/O
 
-   Copyright (C) 1995, 1996, 1998 Free Software Foundation, Inc.
+   Copyright (C) 1995, 1996, 1998, 1999 Free Software Foundation, Inc.
 
    Written by Miles Bader <miles@gnu.ai.mit.edu>
 
@@ -138,7 +138,8 @@ dev_buf_rw (struct dev *dev, size_t buf_offs, size_t *io_offs, size_t *len,
    desired block size, and must be a multiple of the device block size.
    If an error occurs, the error code is returned, otherwise 0.  */
 error_t
-dev_open (struct store_parsed *name, int flags, struct dev **dev)
+dev_open (struct store_parsed *name, int flags, int inhibit_cache,
+	  struct dev **dev)
 {
   error_t err;
   struct dev *new = malloc (sizeof (struct dev));
@@ -161,12 +162,16 @@ dev_open (struct store_parsed *name, int flags, struct dev **dev)
       return ENOMEM;
     }
 
-  new->buf_offs = -1;
-  rwlock_init (&new->io_lock);
+  new->inhibit_cache = inhibit_cache;
   new->owner = 0;
-  new->block_mask = (1 << new->store->log2_block_size) - 1;
-  new->pager = 0;
-  mutex_init (&new->pager_lock);
+  if (!inhibit_cache)
+    {
+      new->buf_offs = -1;
+      rwlock_init (&new->io_lock);
+      new->block_mask = (1 << new->store->log2_block_size) - 1;
+      new->pager = 0;
+      mutex_init (&new->pager_lock);
+    }
   *dev = new;
 
   return 0;
@@ -176,13 +181,16 @@ dev_open (struct store_parsed *name, int flags, struct dev **dev)
 void
 dev_close (struct dev *dev)
 {
-  if (dev->pager != NULL)
-    pager_shutdown (dev->pager);
+  if (!dev->inhibit_cache)
+    {
+      if (dev->pager != NULL)
+	pager_shutdown (dev->pager);
 
-  dev_buf_discard (dev);
+      dev_buf_discard (dev);
 
-  vm_deallocate (mach_task_self (),
-		 (vm_address_t)dev->buf, dev->store->block_size);
+      vm_deallocate (mach_task_self (),
+		     (vm_address_t)dev->buf, dev->store->block_size);
+    }
 
   store_free (dev->store);
 
@@ -196,6 +204,9 @@ dev_sync(struct dev *dev, int wait)
 {
   error_t err;
 
+  if (dev->inhibit_cache)
+    return 0;
+
   /* Sync any paged backing store.  */
   if (dev->pager != NULL)
     pager_sync (dev->pager, wait);
@@ -330,6 +341,22 @@ dev_write (struct dev *dev, off_t offs, void *buf, size_t len,
 		     buf + io_offs, len, amount);
     }
 
+  if (dev->inhibit_cache)
+    {
+      /* Under --no-cache, we permit only whole-block writes.
+	 Note that in this case we handle non-power-of-two block sizes.  */
+
+      struct store *store = dev->store;
+
+      if (offs % store->block_size != 0 || len % store->block_size != 0)
+	/* Not whole blocks.  No can do.  */
+	return EINVAL;
+
+      /* Do a direct write to the store.  */
+      return store_write (dev->store, offs * store->block_size,
+			  buf, len, amount);
+    }
+
   return dev_rw (dev, offs, len, amount, buf_write, raw_write);
 }
 
@@ -397,6 +424,23 @@ dev_read (struct dev *dev, off_t offs, size_t whole_amount,
 	}
     }
 
+  if (dev->inhibit_cache)
+    {
+      /* Under --no-cache, we permit only whole-block reads.
+	 Note that in this case we handle non-power-of-two block sizes.  */
+
+      struct store *store = dev->store;
+
+      if (offs % store->block_size != 0
+	  || whole_amount % store->block_size != 0)
+	/* Not whole blocks.  No can do.  */
+	return EINVAL;
+
+      /* Do a direct read from the store.  */
+      return store_read (dev->store, offs * store->block_size, whole_amount,
+			 buf, len);
+    }
+
   err = dev_rw (dev, offs, whole_amount, len, buf_read, raw_read);
   if (err && allocated_buf)
     vm_deallocate (mach_task_self (), (vm_address_t)*buf, whole_amount);
diff --git a/storeio/dev.h b/storeio/dev.h
index 7927f80d..a4321399 100644
--- a/storeio/dev.h
+++ b/storeio/dev.h
@@ -1,6 +1,6 @@
 /* store `device' I/O
 
-   Copyright (C) 1995, 1996, 1997 Free Software Foundation, Inc.
+   Copyright (C) 1995, 1996, 1997, 1999 Free Software Foundation, Inc.
 
    Written by Miles Bader <miles@gnu.ai.mit.edu>
 
@@ -32,6 +32,20 @@ struct dev
   /* The device to which we're doing io.  */
   struct store *store;
 
+  /* The current owner of the open device.  For terminals, this affects
+     controlling terminal behavior (see term_become_ctty).  For all objects
+     this affects old-style async IO.  Negative values represent pgrps.  This
+     has nothing to do with the owner of a file (as returned by io_stat, and
+     as used for various permission checks by filesystems).  An owner of 0
+     indicates that there is no owner.  */
+  pid_t owner;
+
+  /* Nonzero iff the --no-cache flag was given.
+     If this is set, the remaining members are not used at all
+     and don't need to be initialized or cleaned up.  */
+  int inhibit_cache;
+
+
   /* A bitmask corresponding to the part of an offset that lies within a
      device block.  */
   unsigned block_mask;
@@ -50,21 +64,14 @@ struct dev
 
   struct pager *pager;
   struct mutex pager_lock;
-
-  /* The current owner of the open device.  For terminals, this affects
-     controlling terminal behavior (see term_become_ctty).  For all objects
-     this affects old-style async IO.  Negative values represent pgrps.  This
-     has nothing to do with the owner of a file (as returned by io_stat, and
-     as used for various permission checks by filesystems).  An owner of 0
-     indicates that there is no owner.  */
-  pid_t owner;
 };
 
 /* Returns a pointer to a new device structure in DEV for the device
    NAME, with the given FLAGS.  If BLOCK_SIZE is non-zero, it should be the
    desired block size, and must be a multiple of the device block size.
    If an error occurs, the error code is returned, otherwise 0.  */
-error_t dev_open (struct store_parsed *name, int flags, struct dev **dev);
+error_t dev_open (struct store_parsed *name, int flags, int inhibit_cache,
+		  struct dev **dev);
 
 /* Free DEV and any resources it consumes.  */
 void dev_close (struct dev *dev);
diff --git a/storeio/pager.c b/storeio/pager.c
index 28b5a4e0..e85104c5 100644
--- a/storeio/pager.c
+++ b/storeio/pager.c
@@ -1,6 +1,6 @@
 /* Paging interface for storeio devices
 
-   Copyright (C) 1995, 1996, 1997 Free Software Foundation, Inc.
+   Copyright (C) 1995, 96, 97, 99 Free Software Foundation, Inc.
 
    Written by Miles Bader <miles@gnu.ai.mit.edu>
 
@@ -217,7 +217,7 @@ dev_get_memory_object (struct dev *dev, vm_prot_t prot, memory_object_t *memobj)
 {
   error_t err = store_map (dev->store, prot, memobj);
 
-  if (err == EOPNOTSUPP)
+  if (err == EOPNOTSUPP && !dev->inhibit_cache)
     {
       int created = 0;
 
diff --git a/storeio/storeio.c b/storeio/storeio.c
index 20a2b000..3990387c 100644
--- a/storeio/storeio.c
+++ b/storeio/storeio.c
@@ -1,6 +1,6 @@
 /* A translator for doing I/O to stores
 
-   Copyright (C) 1995, 1996, 1997, 1998 Free Software Foundation, Inc.
+   Copyright (C) 1995, 96, 97, 98, 99 Free Software Foundation, Inc.
 
    Written by Miles Bader <miles@gnu.ai.mit.edu>
 
@@ -35,8 +35,9 @@
 
 static struct argp_option options[] =
 {
-  {"readonly", 'r', 0,	  0, "Disallow writing"},
-  {"writable", 'w', 0,	  0, "Allow writing"},
+  {"readonly", 'r', 0,	  0,"Disallow writing"},
+  {"writable", 'w', 0,	  0,"Allow writing"},
+  {"no-cache", 'c', 0,	  0,"Never cache data--user io does direct device io"},
   {"rdev",     'n', "ID", 0,
    "The stat rdev number for this node; may be either a"
    " single integer, or of the form MAJOR,MINOR"},
@@ -53,10 +54,13 @@ static struct mutex device_lock;
 
 /* Desired store parameters specified by the user.  */
 struct store_parsed *store_name;
-static int readonly = 0;
+static int readonly;
+
+/* Nonzero if user gave --no-cache flag.  */
+static int inhibit_cache;
 
 /* A unixy device number to return when the device is stat'd.  */
-static int rdev = 0;
+static int rdev;
 
 /* Parse a single option.  */
 static error_t
@@ -67,6 +71,8 @@ parse_opt (int key, char *arg, struct argp_state *state)
     case 'r': readonly = 1; break;
     case 'w': readonly = 0; break;
 
+    case 'c': inhibit_cache = 1; break;
+
     case 'n':
       {
 	char *start = arg, *end;
@@ -147,6 +153,9 @@ trivfs_append_args (struct trivfs_control *trivfs_control,
       err = argz_add (argz, argz_len, buf);
     }
 
+  if (!err && inhibit_cache)
+    err = argz_add (argz, argz_len, "--no-cache");
+
   if (! err)
     err = argz_add (argz, argz_len, readonly ? "--readonly" : "--writable");
 
@@ -173,7 +182,8 @@ check_open_hook (struct trivfs_control *trivfs_control,
   if (device == NULL)
     /* Try and open the device.  */
     {
-      err = dev_open (store_name, readonly ? STORE_READONLY : 0, &device);
+      err = dev_open (store_name, readonly ? STORE_READONLY : 0, inhibit_cache,
+		      &device);
       if (err)
 	device = NULL;
       if (err && (flags & (O_READ|O_WRITE)) == 0)