Patch to allow disabling devices for testing failure/recovery scenarios.

By itself this patch does not enable failure testing, but when it is
applied to the kernel, the OBD_FAIL_WRITE() call will activate it.

Patch currently supports loopback, IDE, and UML ubd failures (ignore patch
reject for ubc.c if not using UML).

Enable MDS write failure testing via "echo <num> > /proc/sys/lustre/fail_loc"
where <num> is the number of a write failure breakpoint (OBD_FAIL_MDS_*_WRITE
as defined in the enum in obd_support.h).

diff --git a/lustre/patches/rdonly-2.4.17.diff b/lustre/patches/rdonly-2.4.17.diff
new file mode 100644 (file)
index 0000000..04436eb
--- /dev/null
+++ b/lustre/patches/rdonly-2.4.17.diff
@@ -0,0 +1,115 @@
+--- lum/include/linux/blkdev.h.orig    Thu Mar 28 11:40:24 2002
++++ lum/include/linux/blkdev.h Thu Mar 28 23:38:46 2002
+@@ -228,4 +228,8 @@
+       return retval;
+ }
+ 
++#define CONFIG_DEV_RDONLY
++void dev_set_rdonly(kdev_t, int);
++int dev_check_rdonly(kdev_t);
++void dev_clear_rdonly(int);
+ #endif
+--- lum/drivers/block/blkpg.c.orig     Sun Nov 11 11:20:21 2001
++++ lum/drivers/block/blkpg.c  Thu Mar 28 16:30:41 2002
+@@ -294,3 +294,38 @@
+ }
+ 
+ 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);
+--- lum/drivers/block/loop.c.orig      Fri Dec 21 10:41:53 2001
++++ lum/drivers/block/loop.c   Thu Mar 28 23:39:25 2002
+@@ -471,6 +475,11 @@
+       spin_unlock_irq(&lo->lo_lock);
+ 
+       if (rw == WRITE) {
++#ifdef CONFIG_DEV_RDONLY
++              if (dev_check_rdonly(rbh->b_rdev))
++                      goto err;
++#endif
++
+               if (lo->lo_flags & LO_FLAGS_READ_ONLY)
+                       goto err;
+       } else if (rw == READA) {
+--- lum/drivers/ide/ide-disk.c.orig    Fri Dec 21 10:41:54 2001
++++ lum/drivers/ide/ide-disk.c Thu Mar 28 23:38:41 2002
+@@ -367,6 +367,12 @@
+  */
+ static ide_startstop_t do_rw_disk (ide_drive_t *drive, struct request *rq, unsigned long block)
+ {
++#ifdef CONFIG_DEV_RDONLY
++      if (rq->cmd == WRITE && dev_check_rdonly(rq->rq_dev)) {
++              ide_end_request(1, HWGROUP(drive));
++              return ide_stopped;
++      }
++#endif
+       if (IDE_CONTROL_REG)
+               OUT_BYTE(drive->ctl,IDE_CONTROL_REG);
+       OUT_BYTE(0x00, IDE_FEATURE_REG);
+--- lum/arch/um/drivers/ubd.c.orig     Wed Mar 13 14:04:59 2002
++++ lum/arch/um/drivers/ubd.c  Thu Mar 28 23:39:15 2002
+@@ -693,14 +697,23 @@
+               spin_unlock(&io_request_lock);
+               return(1);
+       }
+-      if((req->cmd == WRITE) && 
+-         ((dev->openflags & O_ACCMODE) == O_RDONLY)){
+-              printk("Write attempted on readonly ubd device %d\n", 
+-                     minor(req->rq_dev));
+-              spin_lock(&io_request_lock);
+-              end_request(0);
+-              spin_unlock(&io_request_lock);
+-              return(1);
++      if (req->cmd == WRITE) {
++#ifdef CONFIG_DEV_RDONLY
++              if (dev_check_rdonly(req->rq_dev)) {
++                      spin_lock(&io_request_lock);
++                      end_request(1);
++                      spin_unlock(&io_request_lock);
++                      return(0);
++              }
++#endif
++              if ((dev->openflags & O_ACCMODE) == O_RDONLY) {
++                      printk("Write attempted on readonly ubd device %d\n",
++                             minor(req->rq_dev));
++                      spin_lock(&io_request_lock);
++                      end_request(0);
++                      spin_unlock(&io_request_lock);
++                      return(1);
++              }
+       }
+ 
+         block = req->sector;