[3.13.y.z extended stable] Patch "UBIFS: fix free log space calculation" has been added to staging queue

Kamal Mostafa kamal at canonical.com
Tue Oct 21 20:09:11 UTC 2014

This is a note to let you know that I have just added a patch titled

    UBIFS: fix free log space calculation

to the linux-3.13.y-queue branch of the 3.13.y.z extended stable tree 
which can be found at:


This patch is scheduled to be released in version

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.13.y.z tree, see



>From 799337904985e62fa37000eaf31107e0039ec465 Mon Sep 17 00:00:00 2001
From: Artem Bityutskiy <artem.bityutskiy at linux.intel.com>
Date: Wed, 16 Jul 2014 15:22:29 +0300
Subject: UBIFS: fix free log space calculation

commit ba29e721eb2df6df8f33c1f248388bb037a47914 upstream.

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

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.

Tested-by: hujianyang <hujianyang at huawei.com>
Reported-by: hujianyang <hujianyang at huawei.com>
Signed-off-by: Artem Bityutskiy <artem.bityutskiy at linux.intel.com>
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
 fs/ubifs/log.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/fs/ubifs/log.c b/fs/ubifs/log.c
index 36bd4ef..bcae6d4 100644
--- a/fs/ubifs/log.c
+++ b/fs/ubifs/log.c
@@ -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;
 	t = (long long)c->ltail_lnum * c->leb_size;

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


More information about the kernel-team mailing list