Re: ubiupdatevol breaks ubi?

[Richard Weinberger <richard@xxxxxx>]

Uwe,

----- Ursprüngliche Mail -----
>	[   57.807978] UBIFS error (ubi0:0 pid 262): ubifs_assert_failed: UBIFS assert
>	failed: c->lhead_lnum != c->ltail_lnum, in fs/ubifs/log.c:412

It took me a while to understand what is going on and why you are facing this.
The assert seems to trigger only if you mount a filesystem where both log heads
point to UBIFS_LOG_LNUM, hence empty log area in initial state, and you change
more filesystem contents than the log can hold at once.

After reviewing UBIFS log code I found something odd.
UBIFS does not initialize c->min_log_bytes, it is by default 0.

c->min_log_bytes can have two values:
- 0: commit in progress, remaining log area may be used
- leb_size: no commit in progress, keep leb_size bytes reserved
  for a future commit.

So having it 0 after a mount seems wrong to me because after mounting
UBIFS there is no commit in progress.

Can you please give this change a try?
With this applied I can no longer trigger the assert.

I'm still not entirely sure whether the assert is correct at all,
review in progress... :-) 

diff --git a/fs/ubifs/super.c b/fs/ubifs/super.c
index 6cfc494050be..b4984da44251 100644
--- a/fs/ubifs/super.c
+++ b/fs/ubifs/super.c
@@ -607,6 +607,9 @@ static int init_constants_early(struct ubifs_info *c)
 	c->max_bu_buf_len = UBIFS_MAX_BULK_READ * UBIFS_MAX_DATA_NODE_SZ;
 	if (c->max_bu_buf_len > c->leb_size)
 		c->max_bu_buf_len = c->leb_size;
+
+	c->min_log_bytes = c->leb_size;
+
 	return 0;
 }

Thanks,
//richard

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