[PATCH] dm: create error table
Add a library function dm_create_error_table() to create a table that rejects
any I/O sent to a device with EIO.
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c
index 10c9439..827b648 100644
--- a/drivers/md/dm-table.c
+++ b/drivers/md/dm-table.c
@@ -237,6 +237,44 @@
return 0;
}
+int dm_create_error_table(struct dm_table **result, struct mapped_device *md)
+{
+ struct dm_table *t;
+ sector_t dev_size = 1;
+ int r;
+
+ /*
+ * Find current size of device.
+ * Default to 1 sector if inactive.
+ */
+ t = dm_get_table(md);
+ if (t) {
+ dev_size = dm_table_get_size(t);
+ dm_table_put(t);
+ }
+
+ r = dm_table_create(&t, FMODE_READ, 1, md);
+ if (r)
+ return r;
+
+ r = dm_table_add_target(t, "error", 0, dev_size, NULL);
+ if (r)
+ goto out;
+
+ r = dm_table_complete(t);
+ if (r)
+ goto out;
+
+ *result = t;
+
+out:
+ if (r)
+ dm_table_put(t);
+
+ return r;
+}
+EXPORT_SYMBOL_GPL(dm_create_error_table);
+
static void free_devices(struct list_head *devices)
{
struct list_head *tmp, *next;
diff --git a/include/linux/device-mapper.h b/include/linux/device-mapper.h
index 010c8c5..61103d2 100644
--- a/include/linux/device-mapper.h
+++ b/include/linux/device-mapper.h
@@ -227,5 +227,11 @@
*/
int dm_swap_table(struct mapped_device *md, struct dm_table *t);
+/*
+ * Prepare a table for a device that will error all I/O.
+ * To make it active, call dm_suspend(), dm_swap_table() then dm_resume().
+ */
+int dm_create_error_table(struct dm_table **result, struct mapped_device *md);
+
#endif /* __KERNEL__ */
#endif /* _LINUX_DEVICE_MAPPER_H */
