Commit ba29e721 authored Jul 16, 2014 by Artem Bityutskiy

UBIFS: fix free log space calculation



Hu (hujianyang <hujianyang@huawei.com>) discovered an issue in the
'empty_log_bytes()' function, which calculates how many bytes are left in the
log:

"
If 'c->lhead_lnum + 1 == c->ltail_lnum' and 'c->lhead_offs == c->leb_size', 'h'
would equalent to 't' and 'empty_log_bytes()' would return 'c->log_bytes'
instead of 0.
"

At this point it is not clear what would be the consequences of this, and
whether this may lead to any problems, but this patch addresses the issue just
in case.

Cc: stable@vger.kernel.org
Tested-by: hujianyang <hujianyang@huawei.com>
Reported-by: hujianyang <hujianyang@huawei.com>
Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>

parent 052c2807

fs/ubifs/log.c

+6 −2

Original line number	Original line	Diff line number	Diff line
	@@ -106,10 +106,14 @@ static inline long long empty_log_bytes(const struct ubifs_info *c)
	h = (long long)c->lhead_lnum * c->leb_size + c->lhead_offs;		h = (long long)c->lhead_lnum * c->leb_size + c->lhead_offs;
	t = (long long)c->ltail_lnum * c->leb_size;		t = (long long)c->ltail_lnum * c->leb_size;

	if (h >= t)		if (h > t)
	return c->log_bytes - h + t;		return c->log_bytes - h + t;
	else		else if (h != t)
	return t - h;		return t - h;
			else if (c->lhead_lnum != c->ltail_lnum)
			return 0;
			else
			return c->log_bytes;
	}		}

	/**		/**