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Commit 06bef945 authored by Artem Bityutskiy's avatar Artem Bityutskiy Committed by Artem Bityutskiy
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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: default avatarArtem Bityutskiy <Artem.Bityutskiy@linux.intel.com>
parent 782759b9

fs/ubifs/debug.c

+11 −0
Original line number Diff line number Diff line
@@ -2802,6 +2802,8 @@ static ssize_t dfs_file_read(struct file *file, char __user *u, size_t count, 
		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 @@ static ssize_t dfs_file_write(struct file *file, const char __user *u, 
		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 @@ int dbg_debugfs_init_fs(struct ubifs_info *c) 
		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:

fs/ubifs/debug.h

+5 −0
Original line number Diff line number Diff line
@@ -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;

};



/**