[dm-devel] [PATCH] dm verity: correcting logic used with corrupted_errs counter

[Ravi Kumar Siddojigari]

Sorry,  Resending the patch for comments with  dm-devel added .

-----Original Message-----
From: Ravi Kumar Siddojigari <rsiddoji at codeaurora.org> 
Sent: Friday, November 20, 2020 6:37 PM
To: 'linux-block at vger.kernel.org' <linux-block at vger.kernel.org>
Cc: 'dm-devel at redhat.com' <dm-devel at redhat.com>
Subject: RE: [PATCH] dm verity: correcting logic used with corrupted_errs
counter

One more question  :
	Current code has DM_VERITY_MAX_CORRUPTED_ERRS  set to 100  can we
reduce this ? or is there any  data that made us to keep this 100 ?
Regards,
Ravi

-----Original Message-----
From: Ravi Kumar Siddojigari <rsiddoji at codeaurora.org> 
Sent: Wednesday, November 18, 2020 6:17 PM
To: 'linux-block at vger.kernel.org' <linux-block at vger.kernel.org>
Subject: [PATCH] dm verity: correcting logic used with corrupted_errs
counter

In verity_handle_err we see that the "corrupted_errs"  is never going to be
more than one as the code will fall through "out" label and hit
panic/kernel_restart on the first error  which is not as expected.. 
Following patch will make sure that corrupted_errs are incremented and only
panic/kernel_restart once it reached DM_VERITY_MAX_CORRUPTED_ERRS.

Signed-off-by: Ravi Kumar Siddojigari <rsiddoji at codeaurora.org>
---
 drivers/md/dm-verity-target.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/drivers/md/dm-verity-target.c b/drivers/md/dm-verity-target.c
index f74982dcbea0..d86900a2a8d7 100644
--- a/drivers/md/dm-verity-target.c
+++ b/drivers/md/dm-verity-target.c
@@ -221,8 +221,10 @@ static int verity_handle_err(struct dm_verity *v, enum
verity_block_type type,
 	/* Corruption should be visible in device status in all modes */
 	v->hash_failed = 1;
 
-	if (v->corrupted_errs >= DM_VERITY_MAX_CORRUPTED_ERRS)
+	if (v->corrupted_errs >= DM_VERITY_MAX_CORRUPTED_ERRS) {
+		DMERR("%s: reached maximum errors", v->data_dev->name);
 		goto out;
+	}
 
 	v->corrupted_errs++;
 
@@ -240,13 +242,13 @@ static int verity_handle_err(struct dm_verity *v, enum
verity_block_type type,
 	DMERR_LIMIT("%s: %s block %llu is corrupted", v->data_dev->name,
 		    type_str, block);
 
-	if (v->corrupted_errs == DM_VERITY_MAX_CORRUPTED_ERRS)
-		DMERR("%s: reached maximum errors", v->data_dev->name);
 
 	snprintf(verity_env, DM_VERITY_ENV_LENGTH, "%s=%d,%llu",
 		DM_VERITY_ENV_VAR_NAME, type, block);
 
 	kobject_uevent_env(&disk_to_dev(dm_disk(md))->kobj, KOBJ_CHANGE,
envp);
+	/* DM_VERITY_MAX_CORRUPTED_ERRS limit not reached yet */
+		return 0;
 
 out:
 	if (v->mode == DM_VERITY_MODE_LOGGING)
--
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