drivers/block/blkpg.c  |   36 ++++++++++++++++++++++++++++++++++++
 drivers/block/loop.c   |    3 +++
 drivers/ide/ide-disk.c |    4 ++++
 3 files changed, 43 insertions(+)

Index: linux-2.4.19/drivers/block/blkpg.c
===================================================================
--- linux-2.4.19.orig/drivers/block/blkpg.c	2002-08-02 20:39:43.000000000 -0400
+++ linux-2.4.19/drivers/block/blkpg.c	2004-04-23 18:24:40.000000000 -0400
@@ -296,3 +296,37 @@
 }
 
 EXPORT_SYMBOL(blk_ioctl);
+
+#define NUM_DEV_NO_WRITE 16
+static int dev_no_write[NUM_DEV_NO_WRITE];
+/*
+ * Debug code for turning block devices "read-only" (will discard writes
+ * silently).  This is for filesystem crash/recovery testing.
+ */
+void dev_set_rdonly(kdev_t dev, int no_write)
+{
+      if (dev) {
+              printk(KERN_WARNING "Turning device %s read-only\n",
+                     bdevname(dev));
+              dev_no_write[no_write] = 0xdead0000 + dev;
+      }
+}
+
+int dev_check_rdonly(kdev_t dev) {
+      int i;
+
+      for (i = 0; i < NUM_DEV_NO_WRITE; i++) {
+      if ((dev_no_write[i] & 0xffff0000) == 0xdead0000 &&
+              dev == (dev_no_write[i] & 0xffff))
+              return 1;
+      }
+      return 0;
+}
+
+void dev_clear_rdonly(int no_write) {
+      dev_no_write[no_write] = 0;
+}
+
+EXPORT_SYMBOL(dev_set_rdonly);
+EXPORT_SYMBOL(dev_check_rdonly);
+EXPORT_SYMBOL(dev_clear_rdonly);
Index: linux-2.4.19/drivers/block/loop.c
===================================================================
--- linux-2.4.19.orig/drivers/block/loop.c	2004-04-23 17:53:56.000000000 -0400
+++ linux-2.4.19/drivers/block/loop.c	2004-04-23 18:23:16.000000000 -0400
@@ -478,6 +478,9 @@
 	spin_unlock_irq(&lo->lo_lock);
 
 	if (rw == WRITE) {
+		if (dev_check_rdonly(rbh->b_rdev))
+			goto err;
+
 		if (lo->lo_flags & LO_FLAGS_READ_ONLY)
 			goto err;
 	} else if (rw == READA) {
Index: linux-2.4.19/drivers/ide/ide-disk.c
===================================================================
--- linux-2.4.19.orig/drivers/ide/ide-disk.c	2004-04-23 17:53:51.000000000 -0400
+++ linux-2.4.19/drivers/ide/ide-disk.c	2004-04-23 18:23:16.000000000 -0400
@@ -558,6 +558,10 @@
  */
 static ide_startstop_t do_rw_disk (ide_drive_t *drive, struct request *rq, unsigned long block)
 {
+	if (rq->cmd == WRITE && dev_check_rdonly(rq->rq_dev)) {
+		ide_end_request(1, HWGROUP(drive));
+		return ide_stopped;
+	}
 	if (IDE_CONTROL_REG)
 		OUT_BYTE(drive->ctl,IDE_CONTROL_REG);