UBIFS: add debugfs knob to switch to R/O mode

This patch adds another debugfs knob which switches UBIFS to R/O mode.
I needed it while trying to reproduce the 'first log node is not CS node'
bug. Without this debugfs knob you have to perform a power cut to repruduce
the bug. The knob is named 'ro_error' and all it does is it sets the
'ro_error' UBIFS flag which makes UBIFS disallow any further writes - even
write-back will fail with -EROFS. Useful for debugging.

Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@linux.intel.com>

1 files changed, 5 insertions, 0 deletions

diff --git a/fs/ubifs/debug.h b/fs/ubifs/debug.h
index 486a8e024fb6..8b8cc4e945f4 100644
--- a/fs/ubifs/debug.h
+++ b/fs/ubifs/debug.h
@@ -79,6 +79,10 @@ typedef int (*dbg_znode_callback)(struct ubifs_info *c,
  * @dfs_chk_lprops: debugfs knob to enable UBIFS LEP properties extra checks
  * @dfs_chk_fs: debugfs knob to enable UBIFS contents extra checks
  * @dfs_tst_rcvry: debugfs knob to enable UBIFS recovery testing
+ * @dfs_ro_error: debugfs knob to switch UBIFS to R/O mode (different to
+ *                re-mounting to R/O mode because it does not flush any buffers
+ *                and UBIFS just starts returning -EROFS on all write
+ *               operations)
  */
 struct ubifs_debug_info {
         struct ubifs_zbranch old_zroot;
@@ -122,6 +126,7 @@ struct ubifs_debug_info {
         struct dentry *dfs_chk_lprops;
         struct dentry *dfs_chk_fs;
         struct dentry *dfs_tst_rcvry;
+        struct dentry *dfs_ro_error;
 };
 
 /**