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>
diff --git a/fs/ubifs/debug.c b/fs/ubifs/debug.c
index 92df3b0..bb31672 100644
--- a/fs/ubifs/debug.c
+++ b/fs/ubifs/debug.c
@@ -2802,6 +2802,8 @@
val = d->chk_fs;
else if (dent == d->dfs_tst_rcvry)
val = d->tst_rcvry;
+ else if (dent == d->dfs_ro_error)
+ val = c->ro_error;
else
return -EINVAL;
@@ -2885,6 +2887,8 @@
d->chk_fs = val;
else if (dent == d->dfs_tst_rcvry)
d->tst_rcvry = val;
+ else if (dent == d->dfs_ro_error)
+ c->ro_error = !!val;
else
return -EINVAL;
@@ -2996,6 +3000,13 @@
goto out_remove;
d->dfs_tst_rcvry = dent;
+ fname = "ro_error";
+ dent = debugfs_create_file(fname, S_IRUSR | S_IWUSR, d->dfs_dir, c,
+ &dfs_fops);
+ if (IS_ERR_OR_NULL(dent))
+ goto out_remove;
+ d->dfs_ro_error = dent;
+
return 0;
out_remove:
diff --git a/fs/ubifs/debug.h b/fs/ubifs/debug.h
index 486a8e02..8b8cc4e 100644
--- a/fs/ubifs/debug.h
+++ b/fs/ubifs/debug.h
@@ -79,6 +79,10 @@
* @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 dentry *dfs_chk_lprops;
struct dentry *dfs_chk_fs;
struct dentry *dfs_tst_rcvry;
+ struct dentry *dfs_ro_error;
};
/**
